Essay Writing

Essay Writing We is not going to deny the fact that there are scammers on the market and you may come across considered one of them. Just watch out and choose reliable services with secure cost strategies like this one. We prepare our consultants in varied forms of formatting and academic writing, in addition to in working with reliable sources. Thanks to this, they perform admirably in any self-discipline and with any deadline. Not each student can grasp the artwork of educational writing. There is nothing to be ashamed of in case expressing your thoughts and ideas utilizing a proper language becomes an inconceivable task certainly. Communicate together with your author via our safe Message Board. Leave text messages, have answers out of your author, and be in the loop regarding the current order progress. We never share any private or cost data with third parties. Everyone will recognize you as the unique writer of all the fantastic essays you submit. Pay for an essay now and get a a hundred% unique paper in 1 hour. A service that is based mostly on high quality doesn’t routinely imply a value sky-excessive. For instance, Pay For Essay offers a rather reasonably priced service that may fit into any budget. Unlimited revisions are free for as much as a month if a paper is long and sophisticated. Message us “write me an essay” now, and we will choose an ideal match in your demand among the main college consultants. Plus, you're a human being with private needs and personal life. Smart time-management is a necessity for each learner. In its type, the essay â€" a prose work, which in a free composition describes personal experiences, emotions, and thoughts on a particular topic, state of affairs or occasion. But generally the coed doesn't have time or literary capability to perform this task on an ideal rating. Please agree with theCookie Policy before proceeding. All of papers you get at Papernow.org are meant for analysis purposes only. QUALITY ASSURANCE Every paper is reviewed for plagiarism and grammar mistakes before supply. We assure to ship one hundred% authentic customized writing with out mistakes and plagiarisms. is a type of creative job, which for a lot of has turn into a type of a breath of contemporary air, diluting the usual boring work. When all you want is to easily have a great relaxation is also understandable. 2000 Master degree-holders could write you a paper in any of these subjects. If it’s an essay, then you'll be able to get pleasure from free limitless revisions inside 2 weeks. Receiving a brand new order, we initially instruct a author to hold out original matter research that's always based on requested sources. Hiring an essay helper is completely okay whenever you’re tired after a day in the college or have work to do. The only thought that seems in the head is â€" “Write my essay for me. In this case, Darwin essay is strictly the place you are on the lookout for. This is one of the greatest providers I've used up to now but I will keep wanting. To turn into part of our group, the applicants should pass English proficiency checks in addition to those on the disciplines they're about to cowl. Most of our specialists hold master’s and PhD levels and are experts in academic writing. We constantly enhance our companies, and our Customer Service Department is no exception. The only approach to turn out to be higher is to take heed to our prospects, so we're all the time ready in your suggestions. Note that almost 60% of assignments are carried out earlier than the deadline. Every paper is double-checked for plagiarism and grammar mistakes on completion. Give us no less than 6 hours, and we’ll write you a a hundred% original essay in accordance with order directions.

Essay Helper

Essay Helper You are guaranteed to obtain a completely original piece with correctly cited sources. Your customized essay will be deleted in 30 days after the supply. Pay for your paper using any of the out there methods, Visa, and MasterCard. A Master’s diploma holding writer will assist you to complete the work in time and up to speed. You ought to turn for affordable essay assist from us as a result of we provide solely one hundred% authentic papers which are cited correctly. We know that plagiarism can lead to terrible consequences, so we never rewrite and resell our papers. If you wish to get a well-written essay on a selected matter, you will have to pay for it. There is an option of asking your good friend to do it free of charge but there isn't any guarantee that your friend is going to agree or write something that is price your teacher's attention. That is why we suggest you place an order right here and forget about your writing issues. There might be a scenario whenever you really feel that the paper you bought isn't perfect. All of papers you get at MasterPapers.com are meant for analysis functions solely. as a result of they've professional author analysis skills, glorious spelling and grammar, and data on relevant software and platforms. right now, and a certified author will set to work on your assignment in less than 15 minutes. Nonetheless, many college students save their essays for the final minute and keep up until morning attempting to string these three,000 words collectively. Our Quality Assurance Team checks every paper for sale for plagiarism and consistency before final supply. There isn't any chance for it to ever appear on the net. Communicate with the author whenever you need utilizing safe chat board and keep observe of the writing progress. We assure that you will receive a totally unique paper from us that is written from scratch based on your individual directions. One extra reason to decide on us among competitors is our Money-Back Guarantee. Even in case if our writers fail to fulfill your expectations, which is sort of inconceivable, you'll not remorse turning for us. If the revision is not applicable, we are going to return your money back. Pay For Essay is a premium service that provides you affordable prices. Order the best custom essay the money can buy and turn the work in safely, understanding that it’s been written by a professional. Give us any topic in any of the 25+ subject fields that we cowl, including MBA, History, Literature, Nursing, and Education. You merely ask your writer to make the mandatory alterations. I'm surprised that every one the writers which have been serving to me over the past month are so good at creating content. Many due to my essay author for the tremendous job you've carried out! I favored everything about it - the author and the truth that they provide quite a few guarantees. We all the time try to fulfill our purchasers at each step of cooperating with us, from ordering to reviewing. You can turn to us with a request, “write my essay” even with essentially the most difficult matters, and we will care for your order. Our flexible pricing coverage makes our providers inexpensive for each scholar. We need every client to inform his/her mates about us, so we create robust relationships with every customer and supply quite a few guarantees to ensure a perfect expertise. For example, we now have a Money-Back Guarantee that permits any buyer to request his/her a refund if he or she isn't satisfied with our work. Besides, we've a loyalty program that makes our company very fashionable amongst college students. We suggest them to purchase papers with discounts in order that they will pay less for his or her first orders, big orders, or when bringing associates. Choose your degree and we'll assign probably the most appropriate author to alleviate your tutorial burden. All of papers you get at Payforessay.web are meant for analysis purposes solely. We never miss deadlines, delivering each composition timely. You don’t have to fret you could miss a deadline and turn a paper in late. Depending on the problem of your paper, deadline, and out there finances, you'll be able to choose between the author varieties and meet your academic goals in the least expensive but handiest fashion.

Australian Essay Writers

Australian Essay Writers You can order essay from the final minute essay writing service. Outsourcing the project to a writing company may be the answer you want, but you don't all the time have money for that. What occurs if it is the end of the month and you're fully broke? We have a huge group of essays writers that have the capability to undertake any writing project you set to us. Our essays writers are so scholastically differed in quite a few methods. It leaves us presently outfitted to sort out even essentially the most extraordinary writing duties. To make you like us even more, we give you free title and references pages. However, each student is different, and many occur to really feel extra comfy expressing their knowledge via a spoken, quite than the written word. If you choose to hire our essay writers we assure you that they manage your time wisely. We know that point is a major facet for you as a pupil since you could have a number of deadlines that you have to meet. Also, we all know that the mental functionality of each pupil is completely different, and you may discover it obscure the requirements of a particular assignment. Thus, you would possibly find yourself submitting incorrect solutions which is able to, in flip, affect your grades. We are at your again and name that will help you manage your time properly by guaranteeing that you just not only save time by comprehending your task but in addition help you in answering appropriately. Not everyone can afford to spend time and efforts to write down essays or some other scientific work. Essay Writer 24 and our licensed writers are happy to assist anytime, and consequently, you’ll get a text written qualitatively and in the shortest attainable time if wanted. Ordering won’t take you a lot time as if you’d carry out this tedious work alone. Expository writing encompasses a wide range of essay variations, such because the comparison and contrast essay, the trigger and effect essay, and the “how to” or process essay. Because expository essays are based mostly on information and not private emotions, writers don’t reveal their emotions or write in the first particular person. You needn't struggle any longer, as you can rent a customized essay writer from us and get the work carried out for you. Our essay writers are standing by to take the work off of your palms. Every essay writer is very certified and absolutely capable of completing the paper on time. That perfect answer slipped away and you're feeling more depressing than ever. If you choose our skilled essya writers service, you’ll work with PhD and MA writers. Before hiring an educational author in our staff, we make certain they will conduct proper analysis and write content on matters from their space of study. The trick to discovering high essay writers is to determine your wants. Once the work is full, the editors check for high quality earlier than submitting the final paper to you. Our company provides solely two weeks free of charge revisions after delivering your last work. Or do you simply want to better present your ideas on a private blog? The cost of your project will depend largely on your scope of labor and the particular skills needed to bring your project to life. The expository essay is an informative piece of writing that presents a balanced evaluation of a subject. In an expository essay, the author explains or defines a subject, using facts, statistics, and examples. We attempt to ship original and unique writing, which is why we guarantee that not a single part of the papers delivered by our writers incorporates fragments of works by other authors. You guessed it; our essay paper writing services are a Mobius strip of pleasure. When it comes to your essay papers, the state of affairs is particularly tough. There’s more to them than simply taking the time you need to sort out your task. Every school paper should be totally researched, plagiarism-free, and nicely-thought-out, which can take days, and even weeks to accomplish.

reThink ELA #006 Interview with Marisa Thompson

How would your students react if you didn’t give them any parameters for a project and simply told them to â€Å"figure it out†? Is this asking for trouble by putting the kids in charge of the classroom or is it an exercise in critical thinking and collaboration? In traditional classrooms, students are often given a very detailed rubric with instructions for completing a project. At the very least, teachers will include what components should be included while other teachers will give even more details about specific themes or examples they want included. What does this type of project really teach the students? Yes, they will learn to follow detailed instructions but is this format teaching them critical thinking or problem solving skills? Are future employers going to give such detailed instructions for work projects? Guaranteed, they will not. My guest today is Marisa Thompson, an English teacher at Carlsbad High School in California. Marisa has 12+ years of experience and has taught every level, from remedial to AP English. She develops curricula on many vertical teams and is an online instructor and guest collaborator at several universities. Marisa has implemented â€Å"instructionless† lessons in her curriculum which the kids have embraced positively. While the parents may be harder to convince of these benefits, many often come around when they realize Marisa is grading based on SKILLS learned instead of focusing on tests and quizzes that require rote memory. Resources mentioned in today’s episode Twitter: @MarisaEThompson About Marisa   The Lancer newspaper article: Mrs. Thompson Finds a New Path to Learning Student website Small Group Discussion Slideshow   A Class with an IMPACT slideshow Michelle WatersI am a secondary English Language Arts teacher, a University of Oklahoma student working on my Master’s of Education in Instructional Leadership and Academic Curriculum with an concentration in English Education, and a NBPTS candidate. I am constantly seeking ways to amplify my students’ voices and choices.

Role Of The National Government And Gender Equality Essay

Role of the National Government †¢ Gender equality should be the prime agenda------ governments do not consider gender equality as a priority, gender equality issues are missing from the budgeting process, and women are not present in the financial, peace, and international negotiations, structures and obligations. Government need to mobilize around gender equality agendas in order to create sufficient political will to support the equal inclusion of women in political decision-making. †¢ Fix some important seats in the cabinet------- Women’s presence within the executive branch is also politically important. The chief executive and the cabinet set the policy agenda of a nation, determine the content of many policies and oversee and guide the policy implementation and administration, including any policies to advance women. Reserve the few important portfolios for the women-------- female ministers are typically given ‘feminine’ portfolios, such as education, health, social welfare or environment. Moreover, governments do not consider gender equality as a priority, gender equality issues are missing from the budgeting process, and women are not present in the financial, peace, and international negotiations, structures and delegations. The participation of a proportion of women in government in all levels should be established as one of the rules of democracy. All governments should thus include a proportion of women. Men and women alike are fitted to hold governmentShow MoreRelatedSchool Related Gender Based Violence1151 Words   |  5 Pageskids can stay in school and advantage from a quality education. A major barrier to the achievement of quality education is the existence of gender-based violence in and around schools. School-related gender-based violence (SRGBV) refers to acts of sexual, physical or psychological violence inflicted on children in and around schools because of stereotypes and roles or norms attributed to or expected of them because of their sex or gendered identity. It additionally alludes to the contrasts in the betweenRead MoreGender Equality in Malaysia1513 Words   |  7 Pagesvariety of roles at the family, community, and society levels, they have been able to contribute to national development and prosperity. In the earlier years, the issue of gender inequality is one which has been publicly reverberating through society for decades. The different religions and cultures of Malaysia have many positive aspects in womens lives. However, it is also the case that women are discriminated against by their religions and cultures, which perpetuate stereotyped gender roles and protectionistRead MoreGlass Ceiling in the Australian Work Force1506 Words   |  7 PagesGlass ceiling in the Australian work force is still an issue in today’s society. I will demonstrate how stereotyping affects males’ perception of women and how it affects women’s perception of gender roles, which supports the concept, that glass ceiling still exists. Stereotyping is to believe that, â€Å"all people or things with similar characteristics are the same,† (â€Å"stereotype†, 2014). The term glass ceiling refers to the invisible barriers that prevent women from succeeding and moving up the metaphoricRead MoreThe On The Gender Machinery1638 Words   |  7 PagesThe Gender machinery In response to some of the described situational GBV’s, the Ministry of Social Welfare, Gender and Children’s Affairs, is the countries national body for social welfare, gender and children’s rights for Sierra Leone. In 2007, 30 women’s rights organisations joined a demonstration against GBV. The national committee is made up of government institutions, UN agencies both national and international organisation and are against GBV. There are also established regional GBV committeesRead MoreEssay about Equality in The Workplace: Dream or Reality?1297 Words   |  6 Pagesbetter pay than women (Cotter, Hermsen and Vanneman). The fight for economic equality has slowed, but it is still necessary in society (Obama). The role of women in society has changed drastically. Women no long have to stay at home and take care of their children. There is now a need for women to work in order to provide for their family. Women continue to dream of a life filled with economic and politically equality. If they continue to work for this dream, it can become a reality. They canRead MoreSynthesis Of Text 12 And 31605 Words   |  7 Pagescan decrease the stress from the balance between work and home, which can also make a contribution to improving the gender equality to some extent. Through comparing the different policies from different developed countries, these three articles try to explore what can impact on the efficiency of the policies and how the policies impact on individuals’ work, family and gender equality. Although the three articles show a change in focus on the impact factor of the policy, Ray et al (2009) stronglyRead MoreThe United Nations Conference On Sustainable Development Essay1380 Words   |  6 PagesForms of Family Maintenance. Other efforts of the UN: Protecting the rights of women ïÆ'Ëœ United Nations Conference On Sustainable Development 2012 The United Nations Conference on Sustainable Development (â€Å"Rio+20†) brought Heads of State and Government to Brazil in 2012, to appraise progress in the implementation of agreements struck since the landmark 1992 United Nations Conference on the Environment and Development in Rio de Janeiro. At â€Å"Rio+20†, countries renewed their political commitmentRead MoreEssay On Women In National Parliaments712 Words   |  3 Pages Women in National Parliaments Worldwide There are many indicators one could choose to measure gender inequality. That being said, one of the most efficient would be to the amount of national parliament seats held by women worldwide. Why is this a good measure of gender equality or lack thereof? As of the present date, women make up 49.55% of the world’s population, but only occupy 23.3% of seats on national parliaments. This is significant because women certainly do not make up a proportional amountRead MoreEven If Women Are To Take Action, Konovalova I. (2004:73)1070 Words   |  5 Pagessuggests, there is a belief among Russian women that their actions would not lead to any profound effect. That is why, the agenda for current feminists in Russia should include the recruiting of men, as when united, both genders can challenge the state and reach a gender equality. The suppression of the information about their native feminist traditions has contributed to a widespread perception in Russian society that feminism is an alien import, an ideology produced by women without a homelandRead MoreReport On Gender Inequality And Inequality Essay1403 Words   |  6 PagesSUBMISSION: REPORT ON GENDER INEQUALITY Introduction Gender inequality is a state in which there is an unequal treatment or perceptions of individuals based on their gender. (forum, 2014). Gender inequality have been brought about by both people perspective and also through inheritance. Gender inequality have brought about degradation of economic status of the country. Gender inequality goes hand in hand with economic status of a country. Gender inequality plays a great role in increase in poverty

Judaism Essay Example For Students

Judaism Essay The religions of Judaism, Hinduism, and Buddhism all have there own beliefs. These beliefs play a big role in a persons everyday life, and influence aspects of their culture such as holidays, diet, social structure, art, and music. In Judaism, they believe that the Sabbath day should be kept holy, and that you should follow the Ten Commandments, the laws of G-d. Their diets consist of kosher food, and have there own New Year, Rosh Hashanah. Hindus believe in Brahman and Karma, which are both a part of the cycle of birth, death, and rebirth. Theyre vegetarians, and have a fairly complex social structure called the caste system. Buddhists believe in Buddhas teachings of the Four Noble Truths. These lead to there belief in following the Eightfold Path in order to reach nirvana. Their art consists of statues of the Buddha, each part having its own meaning. Their music was for the temple and they had their own special way of singing. Two basic beliefs in the religion of Judaism are that t he Sabbath is holy, and that you should follow the Ten Commandments. Sabbath, or Shabbat in Hebrew means cease or desist. It takes place from sunset on Friday until sunset on Saturday, and you are prohibited from doing any work, unless it severely effects your life or health. The mistress of the house lights two white candles and says a blessing. An Omeg is held after Friday night or Saturday afternoon services, where theres usually refreshments, songs, and lectures. It took G-d six days to create the world, and on the seventh day he rested. When G-d gave the Ten Commandments to Moses, he asked that the people also rest on the seventh day of the week. The Ten Commandments are the laws of G-d given to Moses at Mount Sinai. They state that: (1) You shall have no other g-ds before me, (2) I am the only g-d, (3) You shall not take the Lords name in vain, (4) Remember the Sabbath day and keep it holy, (5) Honor your Father and Mother, (6) You shall not kill, (7) You shall not commit adul tery, (8) You shall not steal, (9) You shall not bare false witness against your neighbor, and (10) You shall not covet (be jealous of) your neighbor. The first four are covenants between you and G-d, and the last six are between you and other people. The Ten Commandments were written on two stone tablets by G-d, and are in the Old Testament of the Bible. It is believed that Moses, in fury of the sight of people disobeying G-d, threw down and destroyed them. No one knows where the tablets remain today. Jewish people eat kosher food, and celebrate the holiday of Rosh Hashanah. Kosher, meaning fit or proper is used to refer to food in accordance to Jewish dietary laws. The animals must chew their cud and have cloven hooves. Fish must have distinct scales and fins (no shellfish). The food must not be derived from animals, birds, or fish prohibited in Leviticus 11 or Deuteronomy 14, meat must be slaughtered by the method of shehitah, the meat must be salted and soaked to get rid of all blood, and milk will not be mixed with meat. A special way of preparing and slaughtering the meat (shehitah) also applies. First, a certified (by a rabbi) shohet says a prayer over the animal. Using an extremely sharp, nick-free knife, a swift sweep is made across the throat, making the animal unconscious. All blood is then drained from the animal. Many Jewish people keep a kosher home every day and on holidays like Rosh Hashanah. This is the Jewish New Year, and means, head of the year in Hebrew. It is also sometimes referred to as Yom Ha-Zikkaron (the day of remembrance), or Yom Teruah (the day of the sounding of the shofar). It takes place on the first and second of Tishrei (Jewish calendar), and is one of the most holy days of the year. Its celebrating the creation of the world, and some traditions are the blowing of the shofar and dipping apples into honey. The shofar, or rams horn, is sounded after service, and its notes call for a spiritual awakening. Dipping apples (or bread) into honey is to remind us to have a sweet new year. This is a time for self-evaluation, and to look back on the mistakes youve made in the past year. It is the first of ten days of penitence, and you make up for mistakes that youve made, and confess sins. It ends with the holiday of Yom Kippur, the last day you are judged. .u34de8f3ee90c72bc76ab309491f1fca3 , .u34de8f3ee90c72bc76ab309491f1fca3 .postImageUrl , .u34de8f3ee90c72bc76ab309491f1fca3 .centered-text-area { min-height: 80px; position: relative; } .u34de8f3ee90c72bc76ab309491f1fca3 , .u34de8f3ee90c72bc76ab309491f1fca3:hover , .u34de8f3ee90c72bc76ab309491f1fca3:visited , .u34de8f3ee90c72bc76ab309491f1fca3:active { border:0!important; } .u34de8f3ee90c72bc76ab309491f1fca3 .clearfix:after { content: ""; display: table; clear: both; } .u34de8f3ee90c72bc76ab309491f1fca3 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .u34de8f3ee90c72bc76ab309491f1fca3:active , .u34de8f3ee90c72bc76ab309491f1fca3:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .u34de8f3ee90c72bc76ab309491f1fca3 .centered-text-area { width: 100%; position: relative ; } .u34de8f3ee90c72bc76ab309491f1fca3 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .u34de8f3ee90c72bc76ab309491f1fca3 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .u34de8f3ee90c72bc76ab309491f1fca3 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .u34de8f3ee90c72bc76ab309491f1fca3:hover .ctaButton { background-color: #34495E!important; } .u34de8f3ee90c72bc76ab309491f1fca3 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .u34de8f3ee90c72bc76ab309491f1fca3 .u34de8f3ee90c72bc76ab309491f1fca3-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .u34de8f3ee90c72bc76ab309491f1fca3:after { content: ""; display: block; clear: both; } READ: Steroids EssayIn Hinduism, they believe in Brahman, Karma, and do not eat meat. Brahman is the Supreme Hindu G-d. All other g-ds and goddesses are aspects of Brahman. In fact, everything in the world is part of Brahman. He destroys, recreates, maintains and creates in samsara, which is the cycle of birth, death, and rebirth again. It is a Hindus main goal in life to reach Brahman, and by following ones dharma (rules and regulations one must follow starting at birth), ones soul may eventually be united with him. By following your dharma, you may also have a good next life and be reborn into a higher social class. The total bad and good deed a human soul carries from one lif e to the next is karma. The number of good and bad deeds you do also affects your next life, whether youre human/animal, rich/poor, happy/sad, and things you may experience in this next life. They believe that even though your body dies, your soul is taken into a new body. Hindus diets consist of only vegetation, because they believe that a person in one life could be an animal in another. Therefore, if you killed an animal, it would be like murdering a human. So you would be robbing them of the chance to ever reach their goal in life (reaching Brahman). That is why they treat animals and people as equals. Hindu social structure is broken into special groups based on birth (youd belong to your parents group), called castes. The castes, or varnas, were organized from highest to lowest in the following order: priests/Brahmans, warriors, landowners/ merchants/ herders, servants/ peasants, and the untouchables. Each had its own set of rules regarding cooking, diet, marriage, home, clothing, employment, contact, and much more. For example, you could only marry members of the same class, and a higher Varna could not come into contact with a person of a lower Varna. The highest caste was considered spiritually clean, so when they came in contact with the lower, they were no longer considered pure. This is also why Brahmans/ priests had to be the cooks. Each caste had different jobs that were determined at birth. In 1947, Gandhi rejected the caste system, when India became independent. Beliefs of the religion of Buddhism are the Four Noble Truths and the Eightfold Path. The four parts to the Four Noble Truths are: (1) Life is suffering (Dukka). This recognizes that there is always suffering in life, may it be aging, death, sickness, grief, or separation from loved ones. (2) Desire causes suffering (Samudaya), because when you crave things, you become greedy, and cant always get what you want. (3) Suffering can be ended (Nirodha), because once you stop craving things, you stop suffering. (4) Following the Eightfold Path leads to rejection of desire/suffering (Magga), and reaching nirvana, which is perfect peace. The Eightfold Path says that you have right: view and thought which is the quality of wisdom (panna); speech, action, and livelihood which is the quality of morality (sila); and effort, mindfulness, and concentration which is the quality of meditation (samadhi). All are important in order to reach nirvana. In art, the Buddha is very special, and each part of it has a meaning. His hands are always in one of several positions (mudras). When his hand is on his knee (bhumisparsha), he is calling early beings to be witnesses for his Enlightenment. His hand in his lap represents the physical world. An open hand (abhaya) means blessing and protection, and when the pointer-finger is up, he is favor granting a position. Hands folded in his lap mean he is teaching. His hair/brain is representing his superior knowledge, and is in a top not, or wisdom bun (ushnisa). This was typical for a wandering ascetic. His long earlobes remind us of when the prince wore elaborate earrings, and his robe for when he gave up his property in search of Enlightenment. We recognize him for his long, straight toes, and sitting position (dyanasana). .uc42d79db7de0b8088a970531d139668b , .uc42d79db7de0b8088a970531d139668b .postImageUrl , .uc42d79db7de0b8088a970531d139668b .centered-text-area { min-height: 80px; position: relative; } .uc42d79db7de0b8088a970531d139668b , .uc42d79db7de0b8088a970531d139668b:hover , .uc42d79db7de0b8088a970531d139668b:visited , .uc42d79db7de0b8088a970531d139668b:active { border:0!important; } .uc42d79db7de0b8088a970531d139668b .clearfix:after { content: ""; display: table; clear: both; } .uc42d79db7de0b8088a970531d139668b { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .uc42d79db7de0b8088a970531d139668b:active , .uc42d79db7de0b8088a970531d139668b:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .uc42d79db7de0b8088a970531d139668b .centered-text-area { width: 100%; position: relative ; } .uc42d79db7de0b8088a970531d139668b .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .uc42d79db7de0b8088a970531d139668b .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .uc42d79db7de0b8088a970531d139668b .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .uc42d79db7de0b8088a970531d139668b:hover .ctaButton { background-color: #34495E!important; } .uc42d79db7de0b8088a970531d139668b .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .uc42d79db7de0b8088a970531d139668b .uc42d79db7de0b8088a970531d139668b-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .uc42d79db7de0b8088a970531d139668b:after { content: ""; display: block; clear: both; } READ: A Biography on Martin Luther King Jr. EssayBuddhists temple music is particularly renowned in the west for its two forms of polyphonic singing known as jok-kay (low tone) and bar-da (high tone). In both forms, each of the main chantmasters simultaneously intones three notes (each individually creating a complete chord). They are the only people on Earth that have this vocal ability. This tradition is also known as overtone singing because it is accomplished by means of learning to control the muscles of the vocal cavity and then re-shaping it while singing, thus intensifying the natural overtones of the voice. The body is therefore transformed into an effective overtone am plifier. All of these beliefs are important to each religion in there own way. Theyre what make each religion individual and special. Theyve affected our cultures today greatly in various topics. The Sabbath, Ten Commandments, Rosh Hashanah, and kosher food are all part of Judaism. Hindus believe in Brahman, Karma, and they are vegetarians and are organized into a system of castes. Buddhist statues, music, the Four Noble Truths, and the Eightfold Path are all part of the religion of Buddhism. These things make up their religions.

The Great Gatsby Greed And Wealth Essay free essay sample

, Research Paper In the novel The Great Gatsby by F. Scott Fitzgerald, we learn that every character, except Nick and George, uses wealth as a agency of felicity, which in bend, gets in the manner of their ain ethical motives to move as nice, respectable human existences. Nick Carraway, the chief character in the book, seems to be that nice, respectable human being. He is the voice of ground in the narrative. It is through his point of position that we can separate who is corrupt and who isn t. Nick even says he is an honorable adult male, which gives him some credibleness. He gives a graphic word picture of each character he meets over that summer, and every one of them except a low garage machinist, George Wilson, is claimed by greed and wealth in one signifier or another. For Tom Buchannan, his greed came in the signifier of another adult female. We will write a custom essay sample on The Great Gatsby Greed And Wealth Essay or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The married woman of George Wilson, Myrtle Wilson, is his kept woman. He is corrupt because he is being unpatriotic to his married woman Daisy and George Wilson. His wealthiness is a ground he is unpatriotic because he can utilize his money to acquire any adult female that he wants. Tom is hot tempered, ready to snarl at anyone who gets in his manner. He is besides a racialist, ever speaking about the White Race necessitating to suppress all. It s up to us who are the dominant race to watch out or these other races will hold control of things. Tom is the perfect illustration of the sort of amoral people described in the book. Greedy, ignorant and wealthy. Myrtle Wilson is merely the same. She is dishonorable towards her hubby and speaks extremely of herself. But she is one over Tom because she takes him for granted. He is the one purchasing all of her apparels and beauty accoutrements. He even went every bit far as to purchase her a Canis familiaris. This doesn T seem to trouble oneself Tom a spot though. At her party in New York, things turn a spot rancid though. Tom and Myrtle are contending about something when Myrtle brings the name Daisy into the statement. Hot tempered Tom gets upset with Myrtle and really interrupt her olfactory organ. Myrtle s sister Catherine gives Nick an Interesting piece of information. Neither of them can stand the individual their married to. These two people are likely the most penurious brace in the book. They love each other one minute and hatred eachother the following, being dishonest and disloyal to anything and everything around them. Daisy is closer to being less of a puritan than Myrtle, but she is still sneaky because of her matter with Gatsby. She has an hostel ocence about her, but as the narrative goes on, her immoral properties start to reflect through. In the terminal, Daisy didn t even name Gatsby, and she let him take the incrimination for the car accident that killed Myrtle. Well I tried to swing the wheel- He broke off, and all of a sudden I guessed at the truth. Was Daisy driving? Yes, he said after a minute. Even though Gatsby was willing to do the forfeit for Daisy, Daisy was nowhere to be found when Gatsby needed her most. Finally, Jay Gatsby, the adult male who gives his name to the book, has a different sort of selfishness to him than any of the others. All of his work, whatever it may be, all of his success and all of his parties, even though looking like a nice gesture to other people, were done for something that he wanted for himself. But what he wanted was for person to be happy with him. Ever since he fell in love with Daisy, he hasn t of all time forgotten about her. When Daisy didn t maintain her promise to wait for him, he was devastated, but he still didn t give her up. He went to great lengths to affect her and win her dorsum from Tom. He even kept newspaper cuttings of her. His attempts didn t travel to waste, nevertheless. Daisy did stop up holding a little matter with him. So Gatsby was amoral to Tom. Daisy, that s all over now, he said seriously. It doesn t affair any more. Just state him the truth-that you neer loved him-and it s all wiped out everlastingly. ( 139 ) . Gatsby s attempts to be with Daisy went a small overboard. He is seeking to state Daisy how she felt. Possibly he has fooled himself so much that he believes that they were already together. Throughout that full summer, Nick was capable to many Acts of the Apostless of selfish, dishonest, disloyal, puritan and avaricious behaviour. It s from these people s ignorance that made the terminal bend out how it did. From Gatsby s parties in his house to the slaying that took topographic point in his pool. From the get-togethers in Myrtle s flat to her tragic decease. The clip was every bit corrupt as the people that lived in it. There was neer truly any hope for the destinies that lied waiting for these characters during the summer of 1922. I believe Nick stated it best when he said ; They were careless people # 8230 ; .they smashed up things and animals and so retreated back into their money or their huge sloppiness or whatever it was that kept them together, and allow other people clean up the muss they had made # 8230 ; . ( 187 ) . They were careless people, careless in everything except themselves.

Spectrophotometric Characterization essays

Spectrophotometric Characterization essays In this experiment, there were many goals. The first was to determine the wavelength of maximum absorbance for both the basic and acidic forms of Bromcresol Green (BCG). The second goal was to determine the molar extinction coefficient of BCG. The last goal was to determine the dissociation constant for BCG. Before beginning the experiment, the spectrophotometer needed to be calibrated. Setting the absorbance to 0 when there was nothing (only air) in the machine did this. The first step was to produce an absorption spectra of the acidic BCG and the basic BCG over the range of 340-700 nm. D.D.I H2O was used as the blank. The wavelength of maximum absorbance for the acidic form of BCG was 442.5 nm. The wavelength of maximum absorbance for the basic form of BCG was 616.0 nm. The isobestic wavelength was approximately 410 nm. The next step was to prepare 7 different concentrations of the basic BCG. The maximum absorbencies were recorded for each of the different concentrati ons. These absorbencies were plotted along with the concentrations. The molar extinction coefficient of the basic form of BCG was found to be 3.60x10^4. Beers Law was observed because a linear absorbance-concentration relationship was shown on the graph. The last step required different solutions of BCG, each containing different amounts of acid and base. The absorbencies were taken for these solutions. The dissociation constant for BCG was then found to be 1.80x10^-5 M. This experiment was successful. The dissociation constant was found and was close to the average values for the entire class. Within the science of spectrophotometry, there are many important principles. One of them, Beers Law, says that the amount of light absorbed is proportional to the amount of absorbing substance that the light must pass through. In other words, the molar concentration of a solution is directly proportional to the absorption of the solution (S...

The Strategic Management Process of Walmart Case Study

The Strategic Management Process of Walmart - Case Study Example Elaboration Likelihood Model identified message relevance as one of these factors. According to this model, when message relevance is high, individuals will actively process and evaluate the information in the advertisement when forming or changing attitudes. (Barrie, 2005) When message relevance is low, individuals will not actively process the information in the advertisement, but will instead rely on peripheral message cues to form or change attitudes. Brand Identity is that element of customer perception and awareness which has its focus in the results of a certain kind of projection through the brand equity building measures. This calls for an integrative model which will combine the basic elements of the brand identity and brand equity concepts so as to create a platform for the effective discussion of the Elaboration Likelihood Model. (Jorge et al, 2005) This has been of special relevance for the Walmart company as far as its foray into target market and product variation is c oncerned. Walmart depends to a great extent on the contribution and quality of its human capital. The human capital may be defined as that element of the organisation's operational sphere that is a living, breathing part of the activities that put the innate resources and factors of production into application. This application results in profits arising out of the activities of the human capital and the efficiency with which this resource carries out its tasks. This in turn, has a bearing on the achievement of the organisation's goals. (Jorge et al, 2005) Business Partner The first role of the human resource in today's organisation is that of a business partner. This has come to the fore with the emergence of various service oriented companies that provide intensive marketing services along with the products that are being produced. This is a formal level of institutionalised operations where the organisation profits greatly. This is done by pushing the product in quarters where the effects of regular marketing and promotion cannot reach. It is also an elevated level of salesman ship where the sales agents are offered a share in the business that they make. The advantage of this is that the business partners take a personal interest in the development of a clientele. (Green, 2002. P 111) Further, this serves the two fold purpose of sales and promotion. While there might not be

Space Elevator Research Proposal Example | Topics and Well Written Essays - 750 words

Space Elevator - Research Proposal Example It is a fixed structure as opposed to a vehicle which will be fuel hungry and will have limited capacity of locomotion between the body and the space. A typical space elevator will be a cable like structure extending from the earth's surface into the outer space. It's center of mass will coincide with the Geostationary Earth Orbit, which is at an altitude of 35,786 km. Locomotion will be facilitated by electromagnetic vehicles which will travel along the cables and will be effective in the movement of people, power and other material. (Audacious & Outrageous: Space Elevators) The Space Elevator has caught the fancy of the scientific fraternity all across the globe. As the race to become the builder of the world's first Space Elevator gets heated up, interesting facts emerge. Japanese scientists have gone on record proclaiming that they were in the process of researching the possibility of building a Space Elevator - capable of transporting cargo as well as tourists, for $ 11 Billion. (Ramadge and Schneider) A region off the west coast of Australia has been identified as an Earth Dock, a location perfect for building the base earth station. "The Indian Ocean off Western Australia has been identified as an ideal location for a 'space elevator'; a thin carbon nano tube connecting a barge to a space station, along which supplies could be carried up. Construction could draw on the WA oil industry's expertise in constructing offshore platforms, as well as its material resources. NASA is currently investigating the feasibility of the project." (qtd. in "Lost in Space' Setting a new direction for Australia's space science and industry sector", 27) The structural specifications of the Space Elevator include several parts like the base station, a cable, climbers, and a counterweight. Base stations, in almost all prototypes, are of two varieties - stationary and mobile. Ships and other vessels can serve as mobile base stations while buildings at higher altitudes can suffice as stationary base stations. Both have their own advantages and disadvantages - while it will be cheaper to operate a stationary base station, a mobile base station can be moved so as to avoid any natural calamity. The cables are perhaps the most important part of the setup. It is necessary to manufacture the cables out of a light yet sturdy material. To be economically viable it will be necessary to produce the material at a mass scale and at a viable price. Research has shown that Carbon nano tubes have the capacity to withstand tensile strength of 63 to 177 GPa and are pretty light, as because of the chemical structure of the carbon atoms ensure that there is free space in between the carbon atoms. Thorough research is necessary to produce carbon nano tubes which are stronger. Another point needs to be kept in mind while constructing a nano tube; it will have to bear its own weight along with the weight of the particles which will be transported. Climbers are basically the vessels which will move along the cable. Climbers again will have to be light and heat resistant - they will encounter atmospheric friction while moving up and down a cable. The most important part is the source of power for the climbers. Options like nuclear power, solar energy, laser power beaming are there to be explored. The counterweight is the object which will hold

Mobile Phone Addiction Essay Example for Free

Mobile Phone Addiction Essay The mobile phone is one of the greatest invention in 20th century. We can not imagine how is our life without the mobile phone. It is an obvious truth that the mobile phone gives us benefits in some aspects of life. Using mobile phone distributes our communication to make it easier than before. Besides a mobile phone can provide us with a lot of functions like relaxing with music, chatting or playing games. However, today people especially young people are becoming addicted to using the mobile phone. They can not stay away from their phones, even for a minute. Perhaps, because of the benefits of the mobile phones, most people do not realize lots of negative effects that the mobile phone has brought to us. Using mobile phones too much not only affects our health seriously but also causes some personal problems and limiting communication face to face. In the high-tech world, the mobile phones are equipped with all necessary functions. People can chat together for hours whenever they have time. They talk together from hour to hour, from day to day. As a result, using mobile phone for a long time affects our hea lth. Do you know how dangerous the wave from the cell phone is for our brain? The waves from cell phone are very harmful to our physical body such as our heart and brain. A recent study tells that our brain is seriously damaged when using mobile phone too much. Have you ever experienced the headache with talking on the cell phone for a long time? It is the wave from the mobile phone that causes the headache. Due to the danger of the cell phone wave to our brain, using phones too much can cause a poor memory. Besides, the wave of cell phones is very strong so it can cause heart disease if we keep cell phone near our body, especially under the pillow while sleeping. With many functions of the cell phone, the young can listen to music anytime they want. By using a headphone, people can enjoy some video, some music all time without annoying anyone. However, one effect of listening by earphones for a long time is that it damages our ear, even it can cause deaf. Moreover, the excessive use of cell phones causes teens and young adults to experience restlessness and it can make them feel difficult to fall asleep. It is an obvious fact that using cell phones too much can affect our brain, because sleep loss and damage our ears. Our life is becoming more and more convenient and the mobile phone has become an indispensable and inseparable object. People use mobile phones in every place, every time to manage their business. They talk on the cell phone when working, even when they are on the road. A lot of drivers listen to cell phone conversations while they are driving on the road. Consequently, they can cause dangerous accidents for other drivers on the road. Getting caught up in conversations on a cell phone can lead to the loss of focusing and highly distracted driving. Furthermore, it is generally observed that drivers using cell phones often forget to give proper signals disobey street signs and tend to cut lanes without warning. It is such a careless driving that results in many crashes and fatalities every day. Therefore, our government should give the law to ban drivers from using mobile phones while driving. Besides, another result of using phones too much is the expenses for cell phone cards every month. We often spend a lot of money using mobile phone. Not only the expenses for cell phone cards, sometimes using phones in a public places also causes some problems. We can see some rude people who speak loudly in public places, particularly in libraries, trains and theatres, which disturb other people a lot. For example, the camera of mobile phones sometimes disturbs a persons privacy. Some people use the Bluetooth and the camera in a bad purpose. In short, using mobile phone can cause some personal problem like accidents on the road, money for cell phone cards and some trouble in public places. Mobile phone has become crucial part of our life. One of the most important functions of the phone is that it helps the communication become easier and quicker. However it also causes a lot of problem in communicating. Firstly, cell phone use has effects on the direct human to human interaction. Talking on the cell phones is gradually replacing the communication face to face between people. There was a time when the purpose of a telephone was to convey the important messages and not many people owned telephones. Thus, to talk together about something, they often met directly. Today owning a cell phone is held as a necessity and anyone including children have their cell phone. Therefore, the communication face to face between people is limited. Nowadays parents can be at the work place to talk to their children, to remind them of studying at school. Friends like chatting together for hours by mobile phone so they do not have anything to tell together when meeting at school. It seems that using cell phones too much destroys the pleasure of direct interaction. Another effect in communicating by mobile phone is misunderstanding between people. Always, people send messages to ask for information or congratulate someone. And the problem is that sometimes they forget to type the punctuation marks or they misspell, which makes the receiver misunderstand. More seriously, this can destroy the relationship between them. Therefore, to avoid some problem in communicating by cell phone, people should be careful in using it. Mobile phone is really necessary for our life because of many convenient functions of it. However, sometimes mobile phone can cause us many problems. The advantages or disadvantages of using mobile phones depend on the way how we can use it in right ways or in wrong ways.

Essay --

Two years ago, I started getting frequent headaches and dizziness. I was extremely stubborn and did not want to see my primary physician concerning my change in condition. I was checking my blood pressure more frequently and couldn’t help to notice the increase in pressure. I monitored my vitals for about six months. I tried everything I possibly could to change my lifestyle to aid in the relief. I started to run more and make healthier food choices. Nothing worked! My pressures maintained high. I was reluctant to visit the doctor. I personally did not want to be dependent on medications. After a long discussion with my spouse I realized I was being selfish. I scheduled an office visit the following week for a professional opinion. From the time I entered and left the primary care office, I was treated with dignity and respect. I felt extremely comfortable. I was happy I decided to commit myself. It was a big step to admit I wasn’t healthy. The nursing staff was completely empathic and concerned for me and my family. I could see I was the only thing that mattered while they were i... Essay -- Two years ago, I started getting frequent headaches and dizziness. I was extremely stubborn and did not want to see my primary physician concerning my change in condition. I was checking my blood pressure more frequently and couldn’t help to notice the increase in pressure. I monitored my vitals for about six months. I tried everything I possibly could to change my lifestyle to aid in the relief. I started to run more and make healthier food choices. Nothing worked! My pressures maintained high. I was reluctant to visit the doctor. I personally did not want to be dependent on medications. After a long discussion with my spouse I realized I was being selfish. I scheduled an office visit the following week for a professional opinion. From the time I entered and left the primary care office, I was treated with dignity and respect. I felt extremely comfortable. I was happy I decided to commit myself. It was a big step to admit I wasn’t healthy. The nursing staff was completely empathic and concerned for me and my family. I could see I was the only thing that mattered while they were i...

Wireless Sensor Networks

1. Introduction The increasing interest in wireless sensor networks can be promptly understood simply by thinking about what they essentially are: a large number of small sensing self-powered nodes which gather information or detect special events and communicate in a wireless fashion, with the end goal of handing their processed data to a base station. Sensing, processing and communication are three key elements whose combination in one tiny device gives rise to a vast number of applications [A1], [A2]. Sensor networks provide endless opportunities, but at the same time pose formidable challenges, uch as the fact that energy is a scarce and usually non-renewable resource. However, recent advances in low power VLSI, embedded computing, communication hardware, and in general, the convergence of computing and communications, are making this emerging technology a reality [A3]. Likewise, advances in nanotechnology and Micro Electro-Mechanical Systems (MEMS) are pushing toward networks of tiny distributed sensors and actuators. 2. Applications of Sensor Networks Possible applications of sensor networks are of interest to the most diverse fields. Environmental monitoring, warfare, child education, surveillance, micro-surgery, and griculture are only a few examples [A4]. Through joint efforts of the University of California at Berkeley and the College of the Atlantic, environmental monitoring is carried out off the coast of Maine on Great Duck Island by means of a network of Berkeley motes equipped with various sensors [B6]. The nodes send their data to a base station which makes them available on the Internet. Since habitat monitoring is rather sensitive to human presence, the deployment of a sensor network provides a noninvasive approach and a remarkable degree of granularity in data acquisition [B7]. The same idea lies behind thePods project at the University of Hawaii at Manoa [B8], where environmental data (air temperature, light, wind, relative humidity and rain fall) are gathered by a network of weather sensors embedded in the communication units deployed in the South-West Rift Zone in Volcanoes National Park on the Big Island of Hawaii. A major concern of the researchers was in this case camouflaging the sensors to make them invisible to curious tourists. In Princeton’s Zebranet Project [B9], a dynamic sensor network has been created by attaching special collars equipped with a low-power GPS system to the necks of zebras to onitor their moves and their behavior. Since the network is designed to operate in an infrastructure-free environment, peer-to-peer swaps of information are used to produce redundant databases so that researchers only have to encounter a few zebras in order to collect the data. Sensor networks can also be used to monitor and study natural phenomena which intrinsically discourage human presence, such as hurricanes and forest fires. Joint efforts between Harvard University, the University of New Hampshire, and the University of North Carolina have recently led to the deployment of a wireless sensor etwork to monitor eruptions at Volcan Tungurahua, an active volcano in central Ecuador. A network of Berkeley motes monitored infrasonic signals during eruptions, and data were transmitted over a 9 km wireless link to a base station at the volcano observatory [B10]. Intel’s Wireless Vineyard [B11] is an example of using ubiquitous computing for agricultural monitoring. In this application, the network is expected not only to collect and interpret data, but also to use such data to make decisions aimed at detecting the presence of parasites and enabling the use of the appropriate kind of insecticide.Data collection relies on data mules, small devices carried by people (or dogs) that communicate with the nodes and collect data. In this project, the attention is shifted from reliable information collection to active decisionmaking based on acquired data. Just as they can be used to monitor nat ure, sensor networks can likewise be used to monitor human behavior. In the Smart Kindergarten project at UCLA [B12], wirelessly-networked, sensor-enhanced toys and other classroom objects supervise the learning process of children and allow unobtrusive monitoring by the teacher. Medical research and healthcare can greatly benefit rom sensor networks: vital sign monitoring and accident recognition are the most natural applications. An important issue is the care of the elderly, especially if they are affected by cognitive decline: a network of sensors and actuators could monitor them and even assist them in their daily routine. Smart appliances could help them organize their lives by reminding them of their meals and medications. Sensors can be used to capture vital signs from patients in real-time and relay the data to handheld computers carried by medical personnel, and wearable sensor nodes can store patient data such as identification, history, and treatments.With these ideas in mind, Harvard University is cooperating with the School of Medicine at Boston University to develop CodeBlue, an infrastructure designed to support wireless medical sensors, PDAs, PCs, and other devices that may be used to monitor and treat patients in various medical scenarios [B13]. On the hardware side, the research team has Martin Haenggi is with the Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556; Fax +1 574 631 4393; [email  protected]@nd. edu. Daniele Puccinelli is also with the Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556. reated Vital Dust, a set of devices based on the MICA21 sensor node platform (one of the most popular members of the Berkeley motes family), which collect heart rate, oxygen saturation, and EKG data and relay them over a medium-range (100 m) wireless network to a PDA [B14]. Interactions between sensor networks and humans are already judged controversial. The US has recently app roved the use of a radio-frequency implantable device (VeriChip) on humans, whose intended application is accessing the medical records of a patient in an emergency. Potential future repercussions of this decision have been discussed in the media.An interesting application to civil engineering is the idea of Smart Buildings: wireless sensor and actuator networks integrated within buildings could allow distributed monitoring and control, improving living conditions and reducing the energy consumption, for instance by controlling temperature and air flow. Military applications are plentiful. An intriguing example is DARPA’s self-healing minefield [B15], a selforganizing sensor network where peer-to-peer communication between anti-tank mines is used to respond to attacks and redistribute the mines in order to heal breaches, complicating the progress of enemy troops.Urban warfare is another application that distributed sensing lends itself to. An ensemble of nodes could be deploy ed in a urban landscape to detect chemical attacks, or track enemy movements. PinPtr is an ad hoc acoustic sensor network for sniper localization developed at Vanderbilt University [B16]. The network detects the muzzle blast and the acoustic shock wave that originate from the sound of gunfire. The arrival times of the acoustic events at different sensor nodes are used to estimate the position of the sniper and send it to the base station with a special data aggregation and routing service.Going back to peaceful applications, efforts are underway at Carnegie Mellon University and Intel for the design of IrisNet (Internet-scale Resource-Intensive Sensor Network Services) [B17], an architecture for a worldwide sensor web based on common computing hardware such as Internet-connected PCs and low-cost sensing hardware such as webcams. The network interface of a PC indeed senses the virtual environment of a LAN or the Internet rather than a physical environment; with an architecture based on the concept of a distributed database [B18], this hardware can be orchestrated into a global sensor system hat responds to queries from users. 3. Characteristic Features of Sensor Networks In ad hoc networks, wireless nodes self-organize into an infrastructureless network with a dynamic topology. Sensor networks (such as the one in Figure 1) share these traits, but also have several distinguishing features. The number of nodes in a typical sensor network is much higher than in a typical ad hoc network, and dense deployments are often desired to ensure coverage and connectivity; for these reasons, sensor network hardware must be cheap. Nodes typically have stringent energy limitations, which make them more failure-prone. They are enerally assumed to be stationary, but their relatively frequent breakdowns and the volatile nature of the wireless channel nonetheless result in a variable network topology. Ideally, sensor network hardware should be power-efficient, small, inexpensive, and reliable in order to maximize network lifetime, add flexibility, facilitate data collection and minimize the need for maintenance. Lifetime Lifetime is extremely critical for most applications, and its primary limiting factor is the energy consumption of the nodes, which need to be self-powering. Although it is often assumed that the transmit power associated with acket transmission accounts for the lion’s share of power consumption, sensing, signal processing and even hardware operation in standby mode consume a consistent amount of power as well [C19], [C20]. In some applications, extra power is needed for macro-scale actuation. Many researchers suggest that energy consumption could be reduced by considering the existing interdependencies between individual layers in the network protocol stack. Routing and channel access protocols, for instance, could greatly benefit from an information exchange with the physical layer. At the physical layer, benefits can be obtained wi th ower radio duty cycles and dynamic modulation scaling (varying the constellation size to minimize energy expenditure THIRD QUARTER 2005 IEEE CIRCUITS AND SYSTEMS MAGAZINE 21 External Infrastructure Gateway Base Station Sensing Nodes Figure 1. A generic sensor network with a two-tiered archi1 tecture. See Section 5 for a hardware overview. [D35]). Using low-power modi for the processor or disabling the radio is generally advantageous, even though periodically turning a subsystem on and off may be more costly than always keeping it on. Techniques aimed at reducing the idle mode leakage current in CMOS-based rocessors are also noteworthy [D36]. Medium Access Control (MAC) solutions have a direct impact on energy consumption, as some of the primary causes of energy waste are found at the MAC layer: collisions, control packet overhead and idle listening. Powersaving forward error control techniques are not easy to implement due to the high amount of computing power that they require a nd the fact that long packets are normally not practical. Energy-efficient routing should avoid the loss of a node due to battery depletion. Many proposed protocols tend to minimize energy consumption on forwarding aths, but if some nodes happen to be located on most forwarding paths (e. g. , close to the base station), their lifetime will be reduced. Flexibility Sensor networks should be scalable, and they should be able to dynamically adapt to changes in node density and topology, like in the case of the self-healing minefields. In surveillance applications, most nodes may remain quiescent as long as nothing interesting happens. However, they must be able to respond to special events that the network intends to study with some degree of granularity. In a self-healing minefield, a number of sensing mines ay sleep as long as none of their peers explodes, but need to quickly become operational in the case of an enemy attack. Response time is also very critical in control applications (sensor/actuator networks) in which the network is to provide a delay-guaranteed service. Untethered systems need to self-configure and adapt to different conditions. Sensor networks should also be robust to changes in their topology, for instance due to the failure of individual nodes. In particular, connectivity and coverage should always be guaranteed. Connectivity is achieved if the base station can be reached from any node.Coverage can be seen as a measure of quality of service in a sensor network [C23], as it defines how well a particular area can be observed by a network and characterizes the probability of detection of geographically constrained phenomena or events. Complete coverage is particularly important for surveillance applications. Maintenance The only desired form of maintenance in a sensor network is the complete or partial update of the program code in the sensor nodes over the wireless channel. All sensor nodes should be updated, and the restrictions on the size of the new code should be the same as in the case of wired programming.Packet loss must be accounted for and should not impede correct reprogramming. The portion of code always running in the node to guarantee reprogramming support should have a small footprint, and updating procedures should only cause a brief interruption of the normal operation of the node [C24]. The functioning of the network as a whole should not be endangered by unavoidable failures of single nodes, which may occur for a number of reasons, from battery depletion to unpredictable external events, and may either be independent or spatially correlated [C25]. Faulttolerance is particularly crucial as ongoing maintenance s rarely an option in sensor network applications. Self-configuring nodes are necessary to allow the deployment process to run smoothly without human interaction, which should in principle be limited to placing nodes into a given geographical area. It is not desirable to have humans configure node s for habitat monitoring and destructively interfere with wildlife in the process, or configure nodes for urban warfare monitoring in a hostile environment. The nodes should be able to assess the quality of the network deployment and indicate any problems that may arise, as well as adjust to hanging environmental conditions by automatic reconfiguration. Location awareness is important for selfconfiguration and has definite advantages in terms of routing [C26] and security. Time synchronization [C27] is advantageous in promoting cooperation among nodes, such as data fusion, channel access, coordination of sleep modi, or security-related interaction. Data Collection Data collection is related to network connectivity and coverage. An interesting solution is the use of ubiquitous mobile agents that randomly move around to gather data bridging sensor nodes and access points, whimsically named dataMULEs (Mobile Ubiquitous LAN Extensions) in [C28]. The predictable mobility of the data sink can be used to save power [C29], as nodes can learn its schedule. A similar concept has been implemented in Intel’s Wireless Vineyard. It is often the case that all data are relayed to a base station, but this form of centralized data collection may shorten network lifetime. Relaying data to a data sink causes non-uniform power consumption patterns that may overburden forwarding nodes [C21]. This is particularly harsh on nodes providing end links to base stations, which may end up relaying traffic coming from all ther nodes, thus forming a critical bottleneck for network throughput [A4], [C22], as shown in Figure 2. An interesting technique is clustering [C30]: nodes team up to form clusters and transmit their information to their cluster heads, which fuse the data and forward it to a 22 IEEE CIRCUITS AND SYSTEMS MAGAZINE THIRD QUARTER 2005 sink. Fewer packets are transmitted, and a uniform energy consumption pattern may be achieved by periodic re-clustering. Data redundancy is minimized, as the aggregation process fuses strongly correlated measurements. Many applications require that queries be sent to sensing nodes.This is true, for example, whenever the goal is gathering data regarding a particular area where various sensors have been deployed. This is the rationale behind looking at a sensor network as a database [C31]. A sensor network should be able to protect itself and its data from external attacks, but the severe limitations of lower-end sensor node hardware make security a true challenge. Typical encryption schemes, for instance, require large amounts of memory that are unavailable in sensor nodes. Data confidentiality should be preserved by encrypting data with a secret key shared with the intended receiver. Data integrity should be ensured to revent unauthorized data alteration. An authenticated broadcast must allow the verification of the legitimacy of data and their sender. In a number of commercial applications, a serious disservice to the user of a sensor network is compromising data availability (denial of service), which can be achieved by sleep-deprivation torture [C33]: batteries may be drained by continuous service requests or demands for legitimate but intensive tasks [C34], preventing the node from entering sleep modi. 4. Hardware Design Issues In a generic sensor node (Figure 3), we can identify a power module, a communication block, a processing unit ith internal and/or external memory, and a module for sensing and actuation. Power Using stored energy or harvesting energy from the outside world are the two options for the power module. Energy storage may be achieved with the use of batteries or alternative devices such as fuel cells or miniaturized heat engines, whereas energy-scavenging opportunities [D37] are provided by solar power, vibrations, acoustic noise, and piezoelectric effects [D38]. The vast majority of the existing commercial and research platforms relies on batteries, which dominate the no de size. Primary (nonrechargeable) batteries are often chosen, predominantlyAA, AAA and coin-type. Alkaline batteries offer a high energy density at a cheap price, offset by a non-flat discharge, a large physical size with respect to a typical sensor node, and a shelf life of only 5 years. Voltage regulation could in principle be employed, but its high inefficiency and large quiescent current consumption call for the use of components that can deal with large variations in the supply voltage [A5]. Lithium cells are very compact and boast a flat discharge curve. Secondary (rechargeable) batteries are typically not desirable, as they offer a lower energy density and a higher cost, not to mention the fact that in most pplications recharging is simply not practical. Fuel cells [D39] are rechargeable electrochemical energy- conversion devices where electricity and heat are produced as long as hydrogen is supplied to react with oxygen. Pollution is minimal, as water is the main byproduct of the reaction. The potential of fuel cells for energy storage and power delivery is much higher than the one of traditional battery technologies, but the fact that they require hydrogen complicates their application. Using renewable energy and scavenging techniques is an interesting alternative. Communication Most sensor networks use radio communication, even if lternative solutions are offered by laser and infrared. Nearly all radio-based platforms use COTS (Commercial Off-The-Shelf) components. Popular choices include the TR1000 from RFM (used in the MICA motes) and the CC1000 from Chipcon (chosen for the MICA2 platform). More recent solutions use industry standards like IEEE 802. 15. 4 (MICAz and Telos motes with CC2420 from Chipcon) or pseudo-standards like Bluetooth. Typically, the transmit power ranges between ? 25 dBm and 10 dBm, while the receiver sensitivity can be as good as ? 110 dBm. THIRD QUARTER 2005 IEEE CIRCUITS AND SYSTEMS MAGAZINE 23 Base Station Critical Nodes F igure 2.A uniform energy consumption pattern should avoid the depletion of the resources of nodes located in the vicinities of the base station. Communication Hardware Power Sensors (? Actuators) ADC Memory Processor Figure 3. Anatomy of a generic sensor node. Spread spectrum techniques increase the channel reliability and the noise tolerance by spreading the signal over a wide range of frequencies. Frequency hopping (FH) is a spread spectrum technique used by Bluetooth: the carrier frequency changes 1600 times per second on the basis of a pseudo-random algorithm. However, channel synchronization, hopping sequence search, and the high data rate ncrease power consumption; this is one of the strongest caveats when using Bluetooth in sensor network nodes. In Direct Sequence Spread Spectrum (DSSS), communication is carried out on a single carrier frequency. The signal is multiplied by a higher rate pseudo-random sequence and thus spread over a wide frequency range (typical DSSS radios h ave spreading factors between 15 and 100). Ultra Wide Band (UWB) is of great interest for sensor networks since it meets some of their main requirements. UWB is a particular carrier-free spread spectrum technique where the RF signal is spread over a spectrum as large as several GHz.This implies that UWB signals look like noise to conventional radios. Such signals are produced using baseband pulses (for instance, Gaussian monopulses) whose length ranges from 100 ps to 1 ns, and baseband transmission is generally carried out by means of pulse position modulation (PPM). Modulation and demodulation are indeed extremely cheap. UWB provides built-in ranging capabilities (a wideband signal allows a good time resolution and therefore a good location accuracy) [D40], allows a very low power consumption, and performs well in the presence of multipath fading. Radios with relatively low bit-rates (up to 100 kbps) re advantageous in terms of power consumption. In most sensor networks, high data rates are not needed, even though they allow shorter transmission times thus permitting lower duty cycles and alleviating channel access contention. It is also desirable for a radio to quickly switch from a sleep mode to an operational mode. Optical transceivers such as lasers offer a strong power advantage, mainly due to their high directionality and the fact that only baseband processing is required. Also, security is intrinsically guaranteed (intercepted signals are altered). However, the need for a line of sight and recise localization makes this option impractical for most applications. Processing and Computing Although low-power FPGAs might become a viable option in the near future [D41], microcontrollers (MCUs) are now the primary choice for processing in sensor nodes. The key metric in the selection of an MCU is power consumption. Sleep modi deserve special attention, as in many applications low duty cycles are essential for lifetime extension. Just as in the case of the rad io module, a fast wake-up time is important. Most CPUs used in lower-end sensor nodes have clock speeds of a few MHz. The memory requirements depend on the pplication and the network topology: data storage is not critical if data are often relayed to a base station. Berkeley motes, UCLA’s Medusa MK-2 and ETHZ’s BTnodes use low-cost Atmel AVR 8-bit RISC microcontrollers which consume about 1500 pJ/instruction. More sophisticated platforms, such as the Intel iMote and Rockwell WINS nodes, use Intel StrongArm/XScale 32-bit processors. Sensing The high sampling rates of modern digital sensors are usually not needed in sensor networks. The power efficiency of sensors and their turn-on and turn-off time are much more important. Additional issues are the physical ize of the sensing hardware, fabrication, and assembly compatibility with other components of the system. Packaging requirements come into play, for instance, with chemical sensors which require contact with the envi ronment [D42]. Using a microcontroller with an onchip analog comparator is another energy-saving technique which allows the node to avoid sampling values falling outside a certain range [D43]. The ADC which complements analog sensors is particularly critical, as its resolution has a direct impact on energy consumption. Fortunately, typical sensor network applications do not have stringent resolution requirements.Micromachining techniques have allowed the miniaturization of many types of sensors. Performance does decrease with sensor size, but for many sensor network applications size matters much more than accuracy. Standard integrated circuits may also be used as temperature sensors (e. g. , using the temperaturedependence of subthreshold MOSFETs and pn junctions) or light intensity transducers (e. g. , using photodiodes or phototransistors) [D44]. Nanosensors can offer promising solutions for biological and chemical sensors while concurrently meeting the most ambitious miniaturiza tion needs. 5. Existing Hardware PlatformsBerkeley motes, made commercially available by Crossbow, are by all means the best known sensor node hardware implementation, used by more than 100 research organizations. They consist of an embedded microcontroller, low-power radio, and a small memory, and they are powered by two AA batteries. MICA and MICA2 are the most successful families of Berkeley motes. The MICA2 platform, whose layout is shown in Figure 4, is equipped with an Atmel ATmega128L and has a CC1000 transceiver. A 51-pin expansion connector is available to interface sensors (commercial sensor boards designed for this specific platform are available).Since the MCU is to handle 24 IEEE CIRCUITS AND SYSTEMS MAGAZINE THIRD QUARTER 2005 medium access and baseband processing, a fine-grained event-driven real-time operating system (TinyOS) has been implemented to specifically address the concurrency and resource management needs of sensor nodes. For applications that require a bet ter form factor, the circular MICA2Dot can be used: it has most of the resources of MICA2, but is only 2. 5 cm in diameter. Berkeley motes up to the MICA2 generation cannot interface with other wireless- enabled devices [E47]. However, the newer generations MICAz and Telos support IEEE 802. 15. , which is part of the 802. 15 Wireless Personal Area Network (WPAN) standard being developed by IEEE. At this point, these devices represent a very good solution for generic sensing nodes, even though their unit cost is still relatively high (about $100–$200). The proliferation of different lowerend hardware platforms within the Berkeley mote family has recently led to the development of a new version of TinyOS which introduces a flexible hardware abstraction architecture to simplify multi-platform support [E48]. Tables 1 and 2 show an overview of the radio transceivers and the microcontrollers most commonly used in xisting hardware platforms; an overview of the key features of the pl atforms is provided in Table 3. Intel has designed its own iMote [E49] to implement various improvements over available mote designs, such as increased CPU processing power, increased main memory size for on-board computing and improved radio reliability. In the iMote, a powerful ARM7TDMI core is complemented by a large main memory and non-volatile storage area; on the radio side, Bluetooth has been chosen. Various platforms have been developed for the use of Berkeley motes in mobile sensor networks to enable investigations into controlled mobility, which facilitates eployment and network repair and provides possibilities for the implementation of energy-harvesting. UCLA’s RoboMote [E50], Notre Dame’s MicaBot [E51] and UC Berkeley’s CotsBots [E52] are examples of efforts in this direction. UCLA’s Medusa MK-2 sensor nodes [E53], developed for the Smart Kindergarten project, expand Berkeley motes with a second microcontroller. An on-board power management a nd tracking unit monitors power consumption within the different subsystems and selectively powers down unused parts of the node. UCLA has also developed iBadge [E54], a wearable sensor node with sufficient computational power to process the sensed data.Built around an ATMega128L and a DSP, it features a Localization Unit designed to estimate the position of iBadge in a room based on the presence of special nodes of known location attached to the ceilings. In the context of the EYES project (a joint effort among several European institutions) custom nodes [E55], [C24] have been developed to test and demonstrate energy-efficient networking algorithms. On the software side, a proprietary operating system, PEEROS (Preemptive EYES Real Time Operating System), has been implemented. The Smart-Its project has investigated the possibility of embedding computational power into objects, leading o the creation of three hardware platforms: DIY Smartits, Particle Computers and BTnodes. The DIY S mart-its [E56] have been developed in the UK at Lancaster University; their modular design is based on a core board that provides processing and communication and can be extended with add-on boards. A typical setup of Smart-its consists of one or more sensing nodes that broadcast their data to a base station which consists of a standard core board connected to the serial port of a PC. Simplicity and extensibility are the key features of this platform, which has been developed for the creation of Smart Objects.An interesting application is the Weight Table: four load cells placed underneath a coffee table form a Wheatstone bridge and are connected to a DIY node that observes load changes, determines event types like placement and removal of objects or a person moving a finger across the surface, and also retrieves the position of an object by correlating the values of the individual load cells after the event type (removed or placed) has been recognized [E57]. Particle Computers have been developed at the University of Karlsruhe, Germany. Similarly to the DIY platform, the Particle Smart-its are based on a core board quipped with a Microchip PIC; they are optimized for energy efficiency, scalable communication and small scale (17 mm ? 30 mm). Particles communicate in an ad hoc fashion: as two Particles come close to one another, THIRD QUARTER 2005 IEEE CIRCUITS AND SYSTEMS MAGAZINE 25 Oscillator 7. 3728-MHz DS2401P Silicon Serial No. Antenna Connector Connector LEDs Battery Connection 32. 768-kHz Oscillator 14. 7456-MHz Oscillator ATMEL ATMega 128L CPU CC1000 Transceiver ATMEL AT45DB041 Data Flash Figure 4. Layout of the MICA2 platform. they are able to talk. Additionally, if Particles come near a gateway device, they can be connected to Internet-enabled evices and access services and information on the Internet as well as provide information [E58]. The BTnode hardware from ETHZ [E47] is based on an Atmel ATmega128L microcontroller and a Bluetooth module. Altho ugh advertised as a low-power technology, Bluetooth has a relatively high power consumption, as discussed before. It also has long connection setup times and a lower degree of freedom with respect to possible network topologies. On the other hand, it ensures interoperability between different devices, enables application development through a standardized interface, and offers a significantly higher bandwidth (about 1 Mbps) ompared to many low-power radios (about 50 Kbps). Moreover, Bluetooth support means that COTS hardware can be used to create a gateway between a sensor network and an external network (e. g. , the Internet), as opposed to more costly proprietary solutions [E59]. MIT is working on the ? AMPS (? -Adaptive Multidomain Power-aware Sensors) project, which explores energy-efficiency constraints and key issues such as selfconfiguration, reconfigurability, and flexibility. A first prototype has been designed with COTS components: three stackable boards (processing, radio and power) and an ptional extension module. The energy dissipation of this microsensor node is reduced through a variety of poweraware design techniques [D45] including fine-grain shutdown of inactive components, dynamic voltage and frequency scaling of the processor core, and adjustable radio transmission power based on the required range. Dynamic voltage scaling is a technique used for active power management where the supply voltage and clock frequency of the processor are regulated depending on the computational load, which can vary significantly based on the operational mode [D36], [C20]. The main oal of second generation ? AMPS is clearly stated in [D46] as breaking the 100 ? W average power barrier. Another interesting MIT project is the Pushpin computing system [E60], whose goal is the modelling, testing, and deployment of distributed peer-to-peer sensor networks consisting of many identical nodes. The pushpins are 18 mm ? 18 mm modular devices with a power substrate, an in frared communication module, a processing module (Cygnal C8051F016) and an expansion module (e. g. , for sensors); they are powered by direct contact between the power substrate and layered conductive sheets. 26 MCU Max.Freq. [MHz] Memory Data Size [bits] ADC [bits] Architecture AT90LS8535 (Atmel) 4 8 kB Flash, 512B EEPROM, 512B SRAM 8 10 AVR ATMega128L (Atmel) 8 128 kB Flash, 4 kB EEPROM, 4 kB SRAM 8 10 AVR AT91FR4081 (Atmel) 33 136 kB On-Chip SRAM, 8 Mb Flash 32 — Based on ARM core (ARM7TDMI) MSP430F149 (TI) 8 60 kB + 256B Flash, 2 kB RAM 16 12 Von Neumann C8051F016 (Cygnal) 25 2304B RAM, 32 kB Flash 8 10 Harvard 8051 PIC18F6720 (Microchip) 25 128 kB Flash, 3840B SRAM, 1 kB EEPROM 8 10 Harvard PIC18F252 (Microchip) 40 32 K Flash, 1536B RAM, 256B EEPROM 8 10 Harvard StrongARM SA-1110 (Intel) 133 — 32 — ARM v. 4PXA255 (Intel) 400 32 kB Instruction Cache, 32 kB Data 32 — ARM v. 5TE Cache, 2 kB Mini Data Cache Table 2. Microcontrollers used in sensor node p latforms. Radio (Manufacturer) Band [MHz] Max. Data Rate [kbps] Sensit. [dBm] Notes TR1000 (RFM) 916. 5 115. 2 ? 106 OOK/ASK TR1001 (RFM) 868. 35 115. 2 ? 106 OOK/ASK CC1000 (Chipcon) 300–1,000 76. 8 ? 110 FSK, ? 20 to 10 dBm CC2420 (Chipcon) 2,400 250 ? 94 OQPSK, ? 24 to 0 dBm, IEEE 802. 15. 4, DSSS BiM2 (Radiometrix) 433. 92 64 ? 93 9XStream (MaxStream) 902–928 20 ? 114 FHSS Table 1. Radios used in sensor node platforms. IEEE CIRCUITS AND SYSTEMS MAGAZINE THIRD QUARTER 2005MIT has also built Tribble (Tactile reactive interface built by linked elements), a spherical robot wrapped by a wired skinlike sensor network designed to emulate the functionalities of biological skin [E61]. Tribble’s surface is divided into 32 patches with a Pushpin processing module and an array of sensors and actuators. At Lancaster University, surfaces provide power and network connectivity in the Pin&Play project. Network nodes come in different form factors, but all share the Pin&Play connector, a custom component that allows physical connection and networking through conductive sheets which re embedded in surfaces such as a wall or a bulletin board [E62]. Pin&Play falls in between wired and wireless technologies as it provides network access and power across 2D surfaces. Wall-mounted objects are especially suited to be augmented to become Pin&Play objects. In a demonstration, a wall switch was augmented and freely placed anywhere on a wall with a Pin&Play surface as wallpaper. For applications which do not call for the minimization of power consumption, high-end nodes are available. Rockwellis WINS nodes and Sensoria’s WINS 3. 0 Wireless Sensing Platform are equipped with more powerful rocessors and radio systems. The embedded PC modules based on widely supported standards PC/104 and PC/104-plus feature Pentium processors; moreover, PC/104 peripherals include digital I/O devices, sensors and actuators, and PC-104 products support almost all PC software. PFU Systems’ Plug-N-Run products, which feature Pentium processors, also belong to this category. They offer the capabilities of PCs and the size of a sensor node, but lack built-in communication hardware. COTS components or lower-end nodes may be used in this sense [C32]. Research is underway toward the creation of sensor nodes that are more capable than the motes, yet maller and more power-efficient than higher-end nodes. Simple yet effective gateway devices are the MIB programming boards from Crossbow, which bridge networks of Berkeley motes with a PC (to which they interface using the serial port or Ethernet). In the case of Telos motes, any generic node (i. e. , any Telos mote) can act as a gateway, as it may be connected to the USB port of a PC and bridge it to the network. Of course, more powerful gateway devices are also available. Crossbow’s Stargate is a powerful embedded computing platform (running Linux) with enhanced communication and sensor signal process ing capabilities based n Intel PXA255, the same X-Scale processor that forms the core of Sensoria WINS 3. 0 nodes. Stargate has a connector for Berkeley motes, may be bridged to a PC via Ethernet or 802. 11, and includes built-in Bluetooth support. 6. Closing Remarks Sensor networks offer countless challenges, but their versatility and their broad range of applications are eliciting more and more interest from the research community as well as from industry. Sensor networks have the potential of triggering the next revolution in information technology. The challenges in terms of circuits and systems re numerous: the development of low-power communication hardware, low-power microcontrollers, MEMSbased sensors and actuators, efficient AD conversion, and energy-scavenging devices is necessary to enhance the potential and the performance of sensor networks. System integration is another major challenge that sensor networks offer to the circuits and systems research community. We believ e that CAS can and should have a significant impact in this emerging, exciting area. 27 Platform CPU Comm. External Memory Power Supply WesC (UCB) AT90LS8535 TR1000 32 kB Flash Lithium Battery MICA (UCB, Xbow) ATMega128L TR1000 512 kB Flash AAMICA2 (UCB, Xbow) ATMega128L CC1000 512 kB Flash AA MICA2Dot (UCB, Xbow) ATMega128L CC1000 512 kB Flash Lithium Battery MICAz (UCB, Xbow) ATMega128L CC2420 512 kB Flash AA Telos (Moteiv) MSP430F149 CC2420 512 kB Flash AA iMote (Intel) ARM7TDMI Core Bluetooth 64 kB SRAM, 512 kB Flash AA Medusa MK-2 (UCLA) ATMega103L TR1000 4 Mb Flash Rechargeable Lithium Ion AT91FR4081 iBadge (UCLA) ATMega128L Bluetooth, TR1000 4 Mb Flash Rechargeable Lithium Ion DIY (Lancaster University) PIC18F252 BiM2 64 Kb FRAM AAA, Lithium, Rechargeable Particle (TH) PIC18F6720 RFM TR1001 32 kB EEPROM AAA or Lithium Coin Battery or RechargeableBT Nodes (ETHZ) ATMega128L Bluetooth, CC1000 244 kB SRAM AA ZebraNet (Princeton) MSP430F149 9XStream 4 Mb Flash Lithium Ion Pushpin (MIT) C8051F016 Infrared — Power Substrate WINS 3. 0 (Sensoria) PXA255 802. 11b 64 MB SDRAM, 32 MB + 1 GB Flash Batteries Table 3. Hardware features of various platforms. THIRD QUARTER 2005 IEEE CIRCUITS AND SYSTEMS MAGAZINE Acknowledgments The support of NSF (grants ECS 03-29766 and CAREER CNS 04-47869) is gratefully acknowledged. References General References [A1] I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, â€Å"A survey on sensor networks,† in IEEE Communications Magazine, pp. 02–114, Aug. 2002. [A2] L. B. Ruiz, L. H. A. Correia, L. F. M. Vieira, D. F. Macedo, E. F. Nakamura, C. M. S. Figueiredo, M. A. M. Vieira, E. H. B. Maia, D. Camara, A. A. F. Loureiro, J. M. S. Nogueira, D. C. da Silva Jr. , and A. O. Fernandes, â€Å"Architectures for wireless sensor networks (In Portuguese),† in Proceedings of the 22nd Brazilian Symposium on Computer Networks (SBRC’04), Gramado, Brazil, pp. 167–218, May 2004. Tutorial. ISBN: 85-8 8442-82-5. [A3] C. Y. Chong and S. P. Kumar, â€Å"Sensor networks: Evolution, opportunities, and challenges,† in IEEE Proceedings, pp. 1247–1254, Aug. 003. [A4] M. Haenggi, â€Å"Opportunities and Challenges in Wireless Sensor Networks,† in Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, M. Ilyas and I. Mahgoub, eds. , Boca Raton, FL, pp. 1. 1–1. 14, CRC Press, 2004. [A5] J. Hill, System Architecture for Wireless Sensor Networks. Ph. D. thesis, University of California at Berkeley, Spring 2003. Applications [B6] A. Mainwaring, J. Polastre, R. Szewczyk, D. Culler, and J. Anderson, â€Å"Wireless sensor networks for habitat monitoring,† in First ACM Workshop on Wireless Sensor Networks and Applications, Atlanta, GA, Sept. 002. [B7] A. Cerpa, J. Elson, D. Estrin, L. Girod, M. Hamilton, and J. Zhao, â€Å"Habitat monitoring: Application driver for wireless communications technology,† in ACM SIGCOMM Workshop on Data Comm unications in Latin America and the Caribbean, San Jose, Costa Rica, Apr. 2001. [B8] E. Biagioni and K. Bridges, â€Å"The application of remote sensor technology to assist the recovery of rare and endangered species,† International Journal of High Performance Computing Applications, vol. 16, pp. 315–324, Aug. 2002. [B9] P. Juang, H. Oki, Y. Wang, M. Martonosi, L. Peh, and D.Rubenstein, â€Å"Energy-efficient computing for wildlife tracking: Design tradeoffs and early experiences with ZebraNet,† in Proceedings of the 10th International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS-X), San Jose, CA, Oct. 2002. [B10] G. Werner-Allen, J. Johnson, M. Ruiz, J. Lees, and M. Welsh, â€Å"Monitoring volcanic eruptions with a wireless sensor network,† in Proceedings of the Second European Workshop on Wireless Sensor Networks (EWSN’05), Jan. 2005. [B11] J. Burrell, T. Brooke, and R. Beckwith, â€Å"Vineyard comp uting: Sensor networks in agricultural production,† IEEE Pervasive Computing, vol. , no. 1, pp. 38–45, 2004. [B12] M. Srivastava, R. Muntz, and M. Potkonjak, â€Å"Smart kindergarten: Sensor- based wireless networks for smart developmental problem-solving enviroments,† in Proceedings of the 7th Annual International Conference on Mobile Computing and Networking (MobiCom’01), Rome, Italy, pp. 132–138, 2001. [B13] T. Fulford-Jones, D. Malan, M. Welsh, and S. Moulton, â€Å"CodeBlue: An ad hoc sensor network infrastructure for emergency medical care,† in International Workshop on Wearable and Implantable Body Sensor Networks, London, UK, 2004. [B14] D. Myung, B. Duncan, D. Malan, M. Welsh, M.Gaynor, and S. Moulton, â€Å"Vital dust: Wireless sensors and a sensor network for realtime patient monitoring,† in 8th Annual New England Regional Trauma Conference, Burlington, MA, 2002. [B15] â€Å"Self-healing Mines† http://www. darpa. mil/ ato/programs/SHM/. [B16] M. Maroti, G. Simon, A. Ledeczi, and J. Sztipanovits, â€Å"Shooter localization in urban terrain,† IEEE Computer, vol. 37, pp. 60–61, Aug. 2004. [B17] P. Gibbons, B. Karp, Y. Ke, S. Nath, and S. Seshan, â€Å"IrisNet: An architecture for a worldwide sensor web,† IEEE Pervasive Computing, vol. 2, no. 4, pp. 22–33, 2003. [B18] P. Gibbons, B. Karp, Y. Ke, S.Nath, and S. Seshan, â€Å"IrisNet: An Architecture for Enabling Sensor-Enriched Internet Service,† Tech. Rep. IRP-TR-03-04, Intel Research, Pittsburgh, PA, June 2003. Characteristic Features Lifetime [C19] A. Goldsmith and S. Wicker, â€Å"Design challenges for energy-constrained ad hoc wireless networks,† IEEE Wireless Communications Magazine, vol. 9, pp. 8–27, Aug. 2002. [C20] L. Yuan and G. Qu, â€Å"Energy-efficient Design of Distributed Sensor Networks,† in Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, M. Ilyas and I. M ahgoub, eds. , Boca Raton, FL, pp. 38. 1–38. 19, CRC Press, 2004. [C21] M.Haenggi, â€Å"Twelve Reasons not to Route over Many Short Hops,† in IEEE Vehicular Technology Conference (VTC’04 Fall), Los Angeles, CA, Sept. 2004. [C22] M. Haenggi, â€Å"Energy-Balancing Strategies for Wireless Sensor Networks,† in IEEE International Symposium on Circuits and Systems (ISCAS’03), Bangkok, Thailand, May 2003. Coverage [C23] S. Meguerdichian, F. Koushanfar, M. Potkonjak, and M. Srivastava, â€Å"Coverage problems in wireless ad-hoc sensor networks,† in Proceedings of the 20th Annual Joint Conference of the IEEE Computer and Communications Societies (INFOCOM’01), vol. 3, Anchorage, AK, pp. 1380–1387, Apr. 001. Maintenance [C24] N. Reijers and K. Loangendoen, â€Å"Efficient code distribution in wireless sensor networks,† in Second ACM International Workshop on Wireless Sensor Networks and Applications, San Diego, CA, Sept. 2003. [C 25] D. Ganesan, R. Govindan, S. Shenker, and D. Estrin, â€Å"Highly resilient, energy efficient multipath routing in wireless sensor networks,† in Proceedings of the 2nd ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc’01), Long Beach, CA, pp. 251–254, 2001. Localization and Synchronization [C26] M. Mauve, H. Hartenstein, H. Fuessler, J. Widmer, and W.Effelsberg, â€Å"Positionsbasiertes Routing fuer die Kommunikation zwischen Fahrzeugen,† it—Information Technology (formerly it + ti)—Methoden und innovative Anwendungen der Informatik und Informationstechnik, vol. 44, pp. 278–286, Oct. 2002. [C27] F. Sivrikaya and B. Yener, â€Å"Time synchronization in sensor networks: A survey,† IEEE Network, vol. 18, pp. 45–50, July–Aug. 2004. Data Collection, Routing, and Architectures [C28] R. C. Shah, S. Roy, S. Jain, and W. Brunette, â€Å"Data MULEs: Modeling and analysis of a three-tier arch itecture for sparse sensor networks,† in Ad Hoc Networks Journal, vol. 1, pp. 215–233, Elsevier, Sept. 2003. [C29] A.Chakrabarti, A. Sabharwal, and B. Aazhang, â€Å"Using predictable observer mobility for power efficient design of sensor networks,† in Information Processing in Sensor Networks (IPSN’03), Palo Alto, CA, Apr. 2003. [C30] O. Younis and S. Fahmy, â€Å"HEED: A Hybrid, Energy-Efficient, Distributed Clustering Approach for Ad-hoc Sensor Networks,† in IEEE Transactions on Mobile Computing, vol. 3, pp. 366–379, 2004. [C31] R. Govindan, J. Hellerstein, W. Hong, S. Madden, M. Franklin, and S. Shenker, â€Å"The Sensor Network as a Database,† Tech. Rep. 02–771, University of Southern California, 2002. ftp://ftp. usc. edu/pub/csinfo/ tech-reports/papers/02-771. df. [C32] M. Yarvis and W. Ye, â€Å"Tiered Architectures in Sensor Networks,† in Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, M. Ilyas and I. Mahgoub, eds. , Boca Raton, FL, pp. 13. 1–13. 22, CRC Press, 2004. Security [C33] F. Stajano and R. Anderson, â€Å"The resurrecting duckling: Security issues for ad-hoc wireless networks,† in 7th International Workshop on Security Protocols, Cambridge, UK, Apr. 1999. [C34] T. Martin, M. Hsiao, D. Ha, and J. Krishnaswami, â€Å"Denial-of-service attacks on battery-powered mobile computers,† in Proceedings of the 2nd IEEE Pervasive Computing Conference, Orlando, FL, pp. 09–318, Mar. 2004. Hardware [D35] C. Schurgers, O. Aberthorne, and M. Srivastava, â€Å"Modulation scaling for energy aware communication systems,† in Proceedings of the 2001 International Symposium on Low Power Electronics and Design, 28 IEEE CIRCUITS AND SYSTEMS MAGAZINE THIRD QUARTER 2005 Huntington Beach, CA, pp. 96–99, Aug. 2001. [D36] A. P. Chandrakasan, R. Min, M. Bhardwaj, S. Cho, and A. Wang, â€Å"Power aware wireless microsensor systems,† in 28th European Solid- State Circuits Conference (ESSCIRC’02), Florence, Italy, 2002. [D37] S. Roundy, P. Wright, and J. Rabaey, â€Å"A study of low level vibrations as a power source for ireless sensor nodes,† Computer Communications, vol. 26, pp. 1131–1144, July 2003. [D38] J. Kymissis, C. Kendall, J. Paradiso, and N. Gershenfeld, â€Å"Parasitic power harvesting in shoes,† in Proceedings of the 2nd IEEE International Symposium on Wearable Computers (ISWC’04), Pittsburgh, PA, Oct. 1998. [D39] A. J. Appleby, Fuel Cell Handbook, New York, NY: Van Reinhold Co. , 1989. [D40] W. C. Chung and D. S. Ha, â€Å"An Accurate Ultra WideBand (UWB) Ranging for precision asset location,† in International Conference on UWB Systems and Technologies, Reston, VA, Nov. 2002. [D41] M. Vieira, D. da Silva Jr. C. C. Jr. , and J. da Mata, â€Å"Survey on wireless sensor network devices,† in Proceedings of the 9th IEEE International Conference on Emerging Techno logies and Factory Automation (ETFA’03), Lisbon, Portugal, Sept. 2003. [D42] B. A. Warneke and K. S. J. Pister, â€Å"MEMS for distributed wireless sensor networks,† in Proceedings of the 9th International Conference on Electronics, Circuits and Systems (ICECS’02), vol. 1, Dubrovnik, Croatia, pp. 291–294, 2002. [D43] Z. Karakehayov, â€Å"Low-Power Design for Smart Dust Networks,† in Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, M.Ilyas and I. Mahgoub, eds. , Boca Raton, FL, pp. 37. 1–37. 12, CRC Press, 2004. [D44] B. Warneke, â€Å"Miniaturizing Sensor Networks with MEMS,† in Handbook of Sensor Networks: Compact Wireless and Wired Sensing Systems, M. Ilyas and I. Mahgoub, eds. , Boca Raton, FL, pp. 5. 1–5. 19, CRC Press, 2004. [D45] R. Min, M. Bhardwaj, S. Cho, A. Sinha, E. Shih, A. Wang, and A. P. Chandrakasan, â€Å"An Architecture for a Power-Aware Distributed Microsensor Node,† in IEEE Wor kshop on Signal Processing Systems (SiPS’00), Lafayette, LA, Oct. 2000. [D46] D. D. Wentzloff, B. H.Calhoun, R. Min, A. Wang, N. Ickes, and A. P. Chandrakasan, â€Å"Design considerations for next generation wireless power-aware microsensor nodes,† in Proceedings of the 17th International Conference on VLSI Design, Mumbai, India, pp. 361–367, 2004. Existing Platforms [E47] J. Beutel, O. Kasten, M. Ringwald, F. Siegemund, and L. Thiele, â€Å"Poster abstract: Btnodes—a distributed platform for sensor nodes,† in Proceedings of the First International Conference on Embedded Networked Sensor Systems (SenSys-03), Los Angeles, CA, Nov. 2003. [E48] V. Handziski, J. Polastre, J. H. Hauer, C. Sharp, A. Wolisz, and D. Culler, â€Å"Flexible hardware abstraction for wireless sensor networks,† in Proceedings of the 2nd International Workshop on Wireless Sensor Networks (EWSN 2005), Istanbul, Turkey, Jan. 2005. [E49] R. M. Kling, â€Å"Intel Mote: An En hanced Sensor Network Node,† in International Workshop on Advanced Sensors, Structural Health Monitoring and Smart Structures at Keio University, Tokyo, Japan, Nov. 2003. [E50] K. Dantu, M. Rahimi, H. Shah, S. Babel, A. Dhariwal, and G. Sukhatme, â€Å"Robomote: Enabling Mobility In Sensor Networks,† Tech. Rep.CRES-04-006, University of Southern California. [E51] M. B. McMickell, B. Goodwine, and L. A. Montestruque, â€Å"MICAbot: A robotic platform for large-scale distributed robotics,† in Proceedings of International Conference on Intelligent Robots and Systems (ICRA’03), vol. 2, Taipei, Taiwan, pp. 1600–1605, 2003. [E52] S. Bergbreiter and K. S. J. Pister, â€Å"CotsBots: An Off-the-Shelf Platform for Distributed Robotics,† in Proceedings of the 2003 IEEE International Conference on Intelligent Robots and Systems (ICRA’03), Las Vegas, NV, Oct. 2003. [E53] A. Savvides and M. B.Srivastava, â€Å"A distributed computation platform for wireless embedded sensing,† in 20th International Conference on Computer Design (ICCD’02), Freiburg, Germany, Sept. 2002. [E54] S. Park, I. Locher, and M. Srivastava, â€Å"Design of a wearable sensor badge for smart kindergarten,† in 6th International Symposium on Wearable Computers (ISWC2002), Seattle, WA, pp. 13. 1–13. 22, Oct. 2002. [E55] L. F. W. van Hoesel, S. O. Dulman, P. J. M. Havinga, and H. J. Kip, â€Å"Design of a low-power testbed for Wireless Sensor Networks and verification,† Tech. Rep. R-CTIT-03-45, University of Twente, Sept. 2003. [E56] M.Strohbach, â€Å"The smart-its platform for embedded contextaware systems,† in Proceedings of the First International Workshop on Wearable and Implantable Body Sensor Networks, London, UK, Apr. 2004. [E57] A. Schmidt, M. Strohbach, K. V. Laerhoven, and H. -W. Gellersen, â€Å"Ubiquitous interaction—Using surfaces in everyday environments as pointing devices,† in 7th ERCIM Wo rkshop â€Å"User Interfaces For All,† Chantilly, France, 2002. [E58] M. Beigl, A. Krohn, T. Zimmer, C. Decker, and P. Robinson, â€Å"Aware- Con: Situation aware context communication,† in The Fifth International Conference on Ubiquitous Computing (Ubicomp’03), Seattle, WA, Oct. 003. [E59] J. Beutel, O. Kasten, F. Mattern, K. Roemer, F. Siegemund, and L. Thiele, â€Å"Prototyping sensor network applications with BTnodes,† in IEEE European Workshop on Wireless Sensor Networks (EWSN’04), Berlin, Germany, Jan. 2004. [E60] J. Lifton, D. Seetharam, M. Broxton, and J. Paradiso, â€Å"Pushpin computing system overview: A platform for distributed, embedded, ubiquitous sensor networks,† in Proceedings of the Pervasive Computing Conference, Zurich, Switzerland, Aug. 2002. [E61] J. A. Paradiso, J. Lifton, and M. Broxton, â€Å"Sensate media—multimodal electronic skins as dense sensor networks,† BT Technology Journal, vol. 2, pp. 32â€⠀œ44, Oct. 2004. [E62] K. V. Laerhoven, N. Villar, and H. -W. Gellersen, â€Å"Pin&Mix: When Pins Become Interaction Components. . . ,† in Physical Interaction (PI03)— Workshop on Real World User Interfaces†Ã¢â‚¬â€Mobile HCI Conference, Udine, Italy, Sept. 2003. Daniele Puccinelli received a Laurea degree in Electrical Engineering from the University of Pisa, Italy, in 2001. After spending two years in industry, he joined the graduate program in Electrical Engineering at the University of Notre Dame, and received an M. S. Degree in 2005. He is currently working toward his Ph. D. degree.His research has focused on cross-layer approaches to wireless sensor network protocol design, with an emphasis on the interaction between the physical and the network layer. Martin Haenggi received the Dipl. Ing. (M. Sc. ) degree in electrical engineering from the Swiss Federal Institute of Technology in Zurich (ETHZ) in 1995. In 1995, he joined the Signal and Information Process ing Laboratory at ETHZ as a Teaching and Research Assistant. In 1996 he earned the Dipl. NDS ETH (post-diploma) degree in information technology, and in 1999, he completed his Ph. D. thesis on the analysis, design, and optimization of ellular neural networks. After a postdoctoral year at the Electronics Research Laboratory at the University of California in Berkeley, he joined the Department of Electrical Engineering at the University of Notre Dame as an assistant professor in January 2001. For both his M. Sc. and his Ph. D. theses, he was awarded the ETH medal, and he received an NSF CAREER award in 2005. For 2005/06, he is a CAS Distinguished Lecturer. His scientific interests include networking and wireless communications, with an emphasis on ad hoc and sensor networks. THIRD QUARTER 2005 IEEE CIRCUITS AND SYSTEMS MAGAZINE 29