Eugenics Essay Example | Topics and Well Written Essays - 750 words

Eugenics - Essay Example The foundation of the idea of eugenics is that any species can be manipulated through genetically selecting parents in order to achieve higher levels of attributes in each generation. While this was developed as a science, the concepts took a dark turn when applied to human genetics.Eugenics was used during World War II to support attempts at genocide by Adolph Hitler’s regime. Forced sterilization was a solution that preceded the camp deaths of those fitting into an undesirable framework in keeping the ‘Nordic’ race pure. Through ideas that defined people based on traits of birth or instances of medical problems, eugenics was a false science that allowed for the reasoning behind much of the atrocities of World War II. The foundation of the idea of eugenics is that any species can be manipulated through genetically selecting parents in order to achieve higher levels of attributes in each generation. While this was developed as a science, the concepts took a dark t urn when applied to human genetics. In the early 20th century eugenics thrived as a popular belief system to the point that over 30 states had eugenic programs of sterilization in the United States (Joseph 342). More horrific adaptations of eugenics occurred in Hitler’s Germany. In 1923 Fritz Lenz berated his fellow countrymen for not having kept up with the United States in eugenics studies and programs. Marriage was being prohibited in the United States for people who had mental challenges, as well as those who had epilepsy. Lenz was more specific than the United States in that instead of focusing on the idea of preserving the ‘white’ race, Lenz focused on the ‘Nordic’ race, defining superiority through a narrow set of characteristics (Lifton 23). Lenz clarified his position when he wrote in a paper for his professor Alfred Ploetz that â€Å"race was the criterion of value† and â€Å"the State is not there to see that the individual gets hi s rights, but to serve the race† (Lifton 24). As Nazi Germany began to evolve, the idea of purification was romanticized; the idea of â€Å"a more extensive program of compulsory sterilization than had ever previously been attempted† began a social reform that would lead to the genocide that was the greatest horror of World War II (Lifton 24). Abortion became one of the means through which control of the population of those who had ‘undesirable’ traits was established. German laws were passed in 1933 which allowed abortion and eventually forced it through German health courts who decided the fates of those who were not desired under Hitler’s regime (David, Fleischhacker, and Hohn 110). Bavarian scientists pushed the idea of sterilization and elimination of undesirable traits from the population to the point that compulsory sterilization became the standard. From that step, it was a short leap to massacre. Those who were blessed by the ‘rightâ⠂¬â„¢ traits were encouraged to marry and have children with the state providing for those families through welfare programs who had â€Å"racially valuable children† (Lifton 43). Beyond encouragement, the state engaged in kidnapping children with desirable traits, fostering their growth through programs that also helped to shape their belief systems. Heinrich Himmler developed the program called â€Å"Lebensborn† or â€Å"Spring of Life† which was intended to breed the SS from a ‘superior’ biological gene pool, through which the kidnapping was accomplished. Himmler is quoted as saying â€Å"I really intend to take German blood from wherever it is to be found in the world, to rob it and steal it wherever I can†

The Role of RNA Polymerase and the Death Cap Mushroom Essay Example for Free

The Role of RNA Polymerase and the Death Cap Mushroom Essay Being a health care worker, the role of how substances affect the body are always fascinating and intriguing. The role of the Death Cap Mushroom, which is appropriately named, is one that is simple but can have fatal implications. In Britain, the Death Cap Mushroom is attributed to 75% of all fatalities that are caused by ingesting mushrooms (Kibby, 2006). These are deaths that are certainly avoidable, but yet continue to happen. The Death Cap Mushroom scientific name is the Amanita phallodes. When it is ingested, it causes a deadly reaction in the human body. The major toxin mechanism is the inhibition of RNA polymerase II in DNA reproduction. The reason this becomes deadly is that this is a vital enzyme in the synthesis of the messenger RNA and without it, protein synthesis cannot happen and new cell production ceases. (Karlson-Stiber C, Persson, H (2003). When the human body is no longer able to recreate the template for new cell reproduction, the old cells die and new ones can no longer be reproduced and this quickly causes system failure in the body and the organs begin to fail rapidly. Due to the onset of symptoms taking between 12 and 30 hours to be visible, the damage has already taken place and is irreparable and can quickly lead to death. (Elpel, T (2011). The two vital organs that are affected first are usually the liver and the kidneys. This can quickly become a life threatening process. Although there is no cure for the toxicity, it has been treated with large doses of penicillin and Vitamin C, but there this is not a proven treatment and the only prevention of the ingestion of these mushrooms is safe. In most cases, if the person actually survives, a liver transplant would be needed to allow the person to live. Education on how deadly ingesting the Death Cap mushroom is sorely needed to prevent the unnecessary deaths that it causes each year. References 1.Kibby, Guide to mushrooms of Britain and Europe, Octopus Publishing, (2006) 2.Karlson-Striber C, Persson, H, (2003)Cyto toxic fungi overview-Toxic 3.Elpel, T (2011) Amanitaeac: The Deadly Amanita Family

boeing case study :: essays research papers

Summary William Boeing founded the Boeing airplane company in early 20th century. After strings of acquisition and mergers, this company grew and became the current largest world aerospace industry. Followed by previous reorganizations in 19990s, this company decided to start its branding campaign in May 2001. This campaign was consisting of lots of effort and structural changes for the first time in this corporate history. The media was showing the initial success of this campaign just after its beginning. Few days after the grand opening of the new headquarter in Chicago, which was part of campaign, the world shocked by the act of terrorism. On September 11, 2001 terrorist used this company’s product as weapon of mass destruction to massacre innocent people. Four Boeing airplanes used by terrorist caused a great concern for this company about its swinging campaign. Some serious decision needed to be taken about branding process. Problems Although Boeing’s top management considered this company as a top global brand, critics believed this company did not make adequate changes in regard to its growth, in other words, did not adapt itself to 21st century. Public was thinking of Boeing as a traditional company which does not promote its public image as other similar corporation does. Business Week’s survey suggested that Boeing received no rank among top best 100 companies by public in year 2000. In order to catch up with global growth, Boeing started its branding campaign a bit too expansive and no body predicted such a disaster on septer11, 2001, which caused lots of problems for this company. Goals Boeing moved for right track. They decided to compete with other global brands in terms of public image and goodwill. As Phil Condit, Boeing CEO and chairman, announced at Farnborough air show in 2000, this company goals are focusing on: running healthy core businesses, leverage the company’s strength into both new products and services, and open new frontiers. Achieving these major goals can improve Boeing public image both domestically and internationally. There are other areas of weakness existed within this company such as adaptation to new business and communication methods. Boeing must have more participation in areas of public to prove that it is seeing beyond the traditional boundaries. Solution For achieving its dreams, Boeing needs a total restructure and re-branding campaign. These processes require Boeing a precious plan and research. These plans can guide Boeing thorough its restructure, it can reveal the weakness areas and it can ease the whole process.

Importance of Matrifocal family in the caribbean Essay

The Matrifocal family Is very prominent in the Caribbean. This is noted more as among people of Africans in the regions. Reasons for this diversity, Cultural Retention, Plantation system of slavery, SOCIO economic and the culture of property. Cultural retention, Melville Herkevitts was one of the first researchers to trace the African Origin of the slaves who came to the Americans he believed that despite attempts to strip Africans slaves ot their cultural heritage the practice ot polygyny was retained from the practice. affected by bonding and closeness of mother and child because the husband/ father was somewhat marginal. This pattern remained in the Caribbean society especially about lower class people of African descent. Plantation system, there is the belief that the persistence of the Matrifocal family can be seen as a consequence of the plantation system of slavery, M. C. Smith wrote that under plantation slavery stables families were not given a chance to develop unions of whatever sort, were often broken up as slaves were sold. The unit of mother and child was less likely to be torn apart than a unit of man, woman and child, males were denied family rights which resulted in a system of female centeredness therefore became marginalise. Women now lead their families. It is a well-organized social group which represents a positive adaptauon to the circumstances of poverty. By not tying herself down to a husband. the mother is able to maintain causal relationships with a number of men who can provide her with financial support. The above Information shows that the Matrlfocal family can be regarded as a form of family structure in its own right. It is therefore Important because it shows that a woman doesnt need a man to take care of her and her family, she If fully cable of performing both tasks all by herself. so Matrltocal family Is very Important.

A Crime of Compassion Essay

This woman is not a murderer. Barbara Huttmann is a long time nurse who gave a man named Mac his wish to just die and not continue to suffer. Mac had terminal cancer, was on loads of pain medication that wasn’t working and at a hospital where the policy was to resuscitate any patient that stopped breathing. But he begged her to stop them from resuscitating him and so she did. What Huttmann did was not wrong. Mac had the right to die with dignity and not suffer any longer. The team would rush in after the code button is pushed, get the patient breathing again, and leave the nurse to clean the patient up. He would moan in pain and beg Huttmann to stop them every time. Huttmann begged and pleaded with the Doctor put a no code order on Mac but refused due his beliefs and hospital policies. â€Å"We resuscitated him fifty-two times in one month.† (Huttmann 344) Huttmann had been his nurse for six months  which was long enough for her to know Mac, a well-respected police officer and his wife Maura well. â€Å"It was also long enough to watch Maura’s transformation from a young woman to a haggard, beaten old lady.† (Huttmann 344) Maura has had enough too. Maura sat there for six months and watched her husband battle this horrible disease and then had to sit there and watch him suffer as the hospital team continued to save him numerous times. All of this is occurring regardless of what the family said. This is not what Mac and Maura wanted for him. Regardless of Mac and Maura’s wishes they continued to resuscitate him everytime. Until Huttmann finally decided to do as the patient wished. â€Å"Nothing I have done in my 47 years has taken so much effort as it took not to press that code button.† (Huttmann 345) She did it, Huttmann waited until she knew for certain Mac could not be resuscitated again, and then she pushed that button. Just then Maura walked in and begged â€Å"No†¦don’t let them do this to him†¦..for God’s sake†¦please no more.† (Huttmann 346) That is when Huttmann took Maura in her arms and comforted her the best she could. That is when some people decided that Huttmann was a murderer. Of course she was not a murderer. She was finally doing as Mac and his family wished would be done. Mac and Maura begged her enough to just let him go and be put out of the misery and pain he and his family were going through. Of course Huttmann has to listen to people say these things to her. She did what was right, she granted Mac’s one last wish and did not push that code button. Mac will no longer suffer  because Huttmann decided to stop worrying about the policies of the hospital and focus more on what the patient and his family wanted.

Islam Religion Review Essay Sample

Islam Religion Review Essay Sample Muslim Religion Review Essay Muslim Religion Review Essay Islam refers to a monotheistic religious tradition, which emerged in the 7th century C.E. The word Islam is translated as â€Å"surrender† or â€Å"submission†; the religion is based on the teachings of pronounced Prophet Muhammad as an expression of absolute surrender to the will of Allah, who is the creator as well as the sustainer of the world. The Qur’an, which is the divine text of Islam, encompasses the teaching of the Prophet, which was manifested to Mohammad from Allah. Fundamental to Islam is the conviction that Allah is the one and only true God and has no equality. Islam has many branches and many varieties of those branches. The two branches in the tradition are Sunni and Shi’a each of which assertions to separate meaning of upholding religious authority. One of the unifying traits of Islam is the Five Pillars, which are the basic practices of Islam (Islamweb English). Islam is embodiment of the code of life that God, the creator as well as the Lord of the universe, has manifested for providing guidance to mankind. In order to ensure development of mankind, two elements are required which serve as a resource for sustaining life and to satisfy material necessity of an individual and the society as well as the knowledge of the values of person’s and social behavior to assist human being to fulfill himself and uphold justice and tranquility in mankind living (islamweb english). The Father of the universe has given both of these measures abundantly. To provide for material necessities of man, the Lord has bestowed natural resources at the disposal of man . In a bid to provide for man’s social, spiritual, and cultural necessities, the lord has raised His prophets from amongst men and has manifested to them the value of life, which could provide lines to honest path. This code of life is referred to as Islam, the faith that is proclaimed by all the prophets of God. The common traits that characterize Islam include rationality, practicality and simplicity. Islam is a religion that has no mythology. The teachings are intelligible and simple. It is devoid of superstitions and irrational belies. The concept of singleness of God, the prophet hood of Mohammad, as well as the issue of life after death are the fundamental articles of this belief founded on reason and sound logic. The entire teaching of Islam evolving from those fundamental beliefs is simple an d straightforward. There are no pyramid of priests, nor farfetched abstractions, or complex rites and rituals. Therefore anyone could take a Qur’an literary and interpret its dictates into action (Masters). Islam arouses the faculty of reasoning and exhorting man to apply his intellect. It directs him to view issues in the light of truth. The Qur’an enlightens man to pray to Allah so as Allah may give them knowledge. Additionally, Islam is practical religion which does not permit involvement in unfounded and futile theorizing. It holds that faith is not sheer profession of beliefs; instead it is the prime mainspring of life. Righteous behavior ought to follow faith in God. It holds that religion is to be put in action and not an object of simple lip-service. The Qur’an promises joy to them that believe and act righteously. Islam is also characterized with unity of spirit and matters. The distinctive element of Islam is that it does not differentiate life into waterproof compartments of spirit and matter. It does not advocate for denial of life instead for the fulfillment of life. The religion does not favor asceticism. It also does not force man to keep off from material things. It stresses that spiritual edification is to be met through living sacred in the rough and tumble life and not through renouncing the world as enlightened by the Qur’an(Islamweb English). Therefore, the religion does not accept any separation between† moral â€Å"and â€Å"material â€Å"and â€Å"spiritual† life, and enjoins human being to dedicate his energy to building life on proper moral foundations. It gives a grounding in the fact that material and moral power ought to be welded jointly and that spiritual salvation could be realized through the use of material resources for the well- being of man in the provision of just ends and not through living a life of asceticism or through running away from life challenges. Islam looks to strike a balance between these two main issues of life spiritual and material. It acknowledges that all resources of the universe belong to man, but man was formed to serve a greater purpose that entails development of moral as well as just order, which will satisfy the will of God. The teaching of Islam provides for both spiritual and the temporal necessities of man. Additionally, Islam charges gent to purify his soul and reform his day to day life that is both collective and individual as well as develop the supremacy of claim over great and virtue over vice. Therefore, Islam is in the middle way and the purpose of yielding a moral man in the provision of a just community (Islamweb English). This religion expressly denounces the impression of religion and precisely indicates that its purposes are purification of the soul and rebuilding of the society. Therefore, Islam appears to be a way of life which does not miss any aspect of human existence (Pattern in Islamic Art). There has always been a fine line separating Islamic Mysticism from numerous anti-Islamic heresies. Islamic Mysticism does not ignore the world, it merely withdraws from several of its luxuries. Most of the mujahidin who fought for Islamic reason were mystics. For example, Syed Al-Badawi, which was a device applied in bringing to an end the crusades that caused the people to fight. The Mohammad mystics of Islam refer to themselves as Ahl-Haqq, which means the true follower of real. The source of Islamic mysticism in the description of religion with â€Å"belief† in and adherence to principles of revelation and requirement to act. This religion is more than a formal religion but rather a way of life. A Muslim stays face to face with Allah within all times, and there is no inclusion of separation between his religion and life, his faith and politics with its deep emphasis on the brotherhood of men working harmoniously to live according to Allah will (alam). The ancient Islamic art relays the spiritual and quintessential information about Islam through language and direct symbolism which is both effective and less problematic beyond most of the theoretical interpretations of Islam. A small piece of ancient calligraphy could convey more eloquently of the intelligence and nobility that characterizes Islam beyond several apologetic works of activists. Such is serine, structured, intelligible and highly spiritual trait of Islamic art that results to an accurate understanding of Islamic way of life. As opposed to resent ideas, Islam does not view beauty and art as a luxury; instead, it views beauty as a divine quality as well as suggests that God values beauty. Islamic etics desires beauty to be prevalent and, hence, the art, which makes sure that a Muslim experiences joy of beauty in all parts of his life. He feels the same sense of joy and peace while seated on a traditional carpet, looking at a piece of calligraphy or when praying in the masterpieces of Islamic architecture that extend from the Pacific to the Atlantic. More examples include the Islamic Art of Writing, sacred Architecture of the Islamic Mosque and Aesthetic theories as well as building of an Islamic society (Educating for CulturalCultural Literacy andRespect ). Belief in Mohammad message arose from the belief on Unitarian God. Islam regards itself as a monotheistic religion that was taught through all prophets from Adam to Mohammed. The main beliefs of Islam are the belief in God’s sacred plan and knowledge of what occurs in the world. The belief in the judgment day where everyone will give account for his actions and be rewarded or punished is another fundamental belief of Islam as well as the belief in one God – Allah. Islam acknowledges angels, especially angel Gabriel who was the messengers to various prophets. (Koshhal). The religion views the world as a temporal home as the saint waits to go to Paradise. Islamic religion emphasis on the need for each to fight for his faith irrespective of the costs paid even if it means death of your enemies. It holds that at restrained terms it is justifiable to take away the life of another person when he poses a threat to the Islam well-being. Islam procures that human being was created to live a life without any fault, merely to serve Allah through faithful deeds (Koshhal). The role of women in the Muslim community has changed considerably during the centuries from the conception of Islam about 600 years ago. Their place has been altered depending on shifting social, political and economic circumstances. Despite that the Qur’an holds men and women to be equal before God, women do not have equal access to certain spheres of social life. Historically, Muslim women have not been accorded same treatment as men. Particular rulers as well as numeral legal scholars enforced a system of inequality, which is vindicated through their interpretations of the Qur’an and the ancient customs of the Prophet. However, this view was criticized by the colonial authorities and their western understanding of the rightful place of women in community was adapted by some segment of Muslim population. Subsequently, after Islamic world gained independence in the mid-1900s, women have been trapped between reformers and traditionalists as they strive for dominance within Islamic society (Nicholson). Prior to the emergence of Islam, women were living in traditions that were dominated by men. Women were treated as property, to be married or divorced at wish. The Qur’an recognized the status of women and treated them as equal to men. It acknowledged women’s rights to select their spouses as well as established limits over the practice of polygamy. The Qur’an also recognized marriage to be a contract between a woman and a man and the claim of inheriting wealth and control over their money and property. Beside this, the Qur’an did not alter the male dominance for the Qur’an calls for women to submit to their husbands, it further defines men to be a degree above women in responsibility. Historical facts denote that women participated in the early establishment of Muslim society. It was women who began to follow early revelation of Mohammad. Eventually, women played a vital role in gathering revelations from both oral and written sources into a so litary, authoritative text. It was the nature of the Prophet Mohammad to consult women and highly value their opinion. For example, his wife Kadija was his prime advisor and supporter (Ahmad). Following his death, honorable women were consulted of who his successor would be. It is from this time that the Muslim started to adapt to the colonist way and ended up secluding the women. Men together with women had different, complementary roles within the Muslim communities. The husband was charged with protection and provision while the wife was responsible for maintaining the home and bringing up children. Notably, beside the Qur’an teaching that husband and wife were equal before God, women still remained subordinate to men. During the early 1900s, the state of freshly autonomous Muslim country like Turkey took the challenge of modernizing the woman’s role. Additionally, poor performing economy has compelled women to be engaged in other activities beyond their traditional roles. Moreover, factors like labor and war have caused the number of households run by females. A number of Muslim women have been running grassroots firms, involved indevelopment projects, social activities and charitable associations (lPipes). According to the Qur’an, the same duties and responsibilities are bestowed upon men and women which render them equal rights to pledge for rewards. Notwithstanding, particular factors have contributed to limiting women’s participation in Islamic religious life. These consist of lack of education, social customs, and idea of ritual purity. The particular restriction on the involvement of women in Muslim religious issues and the manners that the women have responded to such restriction varies across the Islamic world. Moreover, in 1900s the emerging roles of women within the society formed fresh opportunities for women in the religious domain as well (the Natural Bases for Natural Light). The Qur’an is not a merely series of strict orders which does not contain comments but rather comprises of laws and history, interpretation and exhortation of creation. In the same way that the Qur’an stipulates rules of conduct in the nature of law on several instances, so it also remarks about the existing and being. The Qur’an talks about the creation of men and women and from this accusations are then leveled against Islam as containing disparaging attitude to women on the strength of its theories (islamway). Islam depicts a woman as sexually desirous and more passionate than the man. In fact, such understanding determines the position of a woman in the ancient period of Islam. According to Islamic perception, both the man and the woman yearning for intercourse, when their bodies experiences same processes, yielding same pleasure as well as physical climaxes. Contrary to the ancient western perception of sexual art as a battlefield in which men expresses their supremacy onto women, Islam views it as a caring, shared pleasure. Therefore, it could be noted that sexual gratification results into a harmonized social order, hence, flourishing the society. Islam holds that female’s desire for sex is greater than that of man. It views â€Å"the woman as the hunter and the man as the passive victim† of the woman ardor, in fact, sexual desire makes her the â€Å"symbol of unreason, disorder, the anti-divine force of nature and discipline of the devil†. Such view could spring from woman’s higher physical capability for sex or it could be traced back to Muhammad encounters. Regardless of the source, women’s sexuality is taken as being more powerful, hence posing a threat to the society. On the same note, Islam advocates for sexual satisfaction, it again reflects unrestrained women to be the more dangerous as compared to male’s endeavoring to fulfill God’s commands. Coupled with such rampant desire and irresistible attractiveness bestows women power over men and this rivals God. When this would be left an attended it could lead to men becoming victims and thus abandon them from God. This would lead to â€Å"fitna† a term which implies civil problems amongst believers. Islam perceives â€Å"fitna† as negative and anti-social power of women In Arabic world in case a man is faced by a woman, the â€Å"fitna† will emerge, since women’s lusts would lead to anarchy ( w). Therefore, a conclusion can be made from the above: Islam restricts on sexuality driven by a concern to sustain the social pattern rather than the moral consideration. Additionally, Islam establishes a range of institutional contrivances aimed at repressing female sexuality. Thus, the prime aim is to keep off men, obstructing romantic love, as well as rendering female powerless. Realization that women were capable of seducing men, set the society to prevent such from happening through creating separate rooms and limiting contacts between the sexes. According to the Shari’a when a man and a woman are left on their own they are to have indulged in sexual intercourses, thus, all ought to be done to avoid these situations from happening. Notably, physical separation of sexes attributes to daily life in Islam. Thus, any man or woman regarded as prospectively sexually appealing to the other and is kept away from each other (Islamweb English). Islamic civilization promotes women to remain indoors as well as perceives women as servants. Men are given the ability and rights to hold their women at home. Typical house, in this case, is designed with walls on the outside and windows facing the inner country yards, hence increasing privacy. Inside the house, the construction also splits the male from female places. (Koshhal).

Electronic Engineer Essays

Electronic Engineer Essays Electronic Engineer Essay Electronic Engineer Essay International Conference on Modelling and Simulation Path Loss Effect on Energy Consumption in a WSN ? Krishna Doddapaneni,? Enver Ever,? Orhan Gemikonakli,†  Ivano Malavolta,? Leonardo Mostarda,†  Henry Muccini Communications Department, School of Engineering Information Sciences, Middlesex University, UK Email:{k. doddapaneni, e. ever, o. gemikonakli, l. mostarda}@mdx. ac. uk †  Dipartimento Di Informatica De L’Aquila Via Vetoio L’Aquila 67100, Italy Email:{ivano. malavolta,henry. muccini}@univaq. it ? ComputerAbstract- Energy consumption of nodes is a crucial factor that constrains the networks life time for Wireless Sensor Networks (WSNs). WSNs are composed of small sensors equipped with lowpower devices, and have limited battery power supply. The main concern in existing architectural and optimisation studies is to prolong the network lifetime. The lifetime of the sensor nodes is affected by different components such as the microprocessor, the sensing module and the wireless transmitter/receiver. The existing works mainly consider these components to decide on best deployment, topology, protocols and so on.Recent studies have also considered the monitoring and evaluation of the path loss caused by environmental factors. Path loss is always considered in isolation from the higher layers such as application and network. It is necessary to combine path loss computations used in physical layer, with information from upper layers such as application layer for a more realistic evaluation. In this paper, a simulation-based study is presented that uses path-loss model and application layer information in order to predict the network lifetime. Physical environment is considered as well.We show that when path-loss is introduced, increasing the transmission power is needed to reduce the amount of packets lost. This presents a tradeoff between the residual energy and the successful transmission rate when more realistic settings are employed for simulation. It is a challenging task to optimise the transmission power of WSNs, in presence of path loss, because although increasing the transmission power reduces the residual energy, it also reduces the number of retransmissions required. Index Terms- attenuation; path loss; wireless sensor networks; energy consumed; life time Evaluation tools Analytical modelingSimulators Real Deployment Test Beds Fig. 1. Performance evaluation methods I. I NTRODUCTION Recent advances in wireless communications and electronics have enabled the development of wireless sensor networks (WSNs), which comprise many low cost, low power, and multifunctional sensor nodes to accomplish certain sensing tasks in an intelligent manner. A sensor network is a special type of network which generally consists of a data acquisition system and a data distribution system. The unique characteristics of WSNs in terms of data collection and energy constrains, separate them from other communication networks.In Figure 1 we show the most common techniques for performance evaluation that are analytical modelling, simulation and benchmarking. The existing studies consider benchmarking in form of test beds and measurements for real deployment. The energy constrains of WSNs, limits their processing capabilities and communication. Therefore, using one of these performance evaluation methods, and analysis of deployment and management of such complex systems is a challenging task [1]. Due to inherent complexity and diverse nature of WSNs (dynamic topology, wireless channel characteristics, mobility, 978-0-7695-4682-7/12 $26. 0  © 2012 IEEE DOI 10. 1109/UKSim. 2012. 87 569 density of the nodes etc. ), analytical methods may become inappropriate as they require certain simpli? cations to model and predict the performance of the system. The simpli? cations may lead to inaccurate results in case of unrealistic assumptions [2],[3]. Experimental studies such as [4],[5],[6],[7] are not always practical for evaluation of systems with different architectures and under various conditions, mainly because of the dif? culties in deployment of real systems. Potential dif? ulties associated may be deploying tens or hundreds of sensor nodes in the physical environment, program the nodes and monitor their behaviour, the high costs involved in obtaining the instrumentation and other aspects such as fault tolerance, and scalability. It is well known that when it comes to benchmarking, the results in many cases cannot be extrapolated to suit the changes in the system or environment. Hence, testing and performance evaluation of WSNs through analytical modelling, real deployment and test beds can become complex, inaccurate, time consuming and/or costly.Simulation is currently the most widely adopted method for analyzing WSNs. Simulation studies provide quicker evaluation, optimisation and modi? cations of the proposed algorithms and protocols at design, development and implementation stages. A number of simulation tools are available with different features, models, architectures and characteristics for performance evaluation in WSNs. Packet level simulators offer various optimisation methods for free space scenarios and avoid the effects of path loss 1 that may be caused by different obstacles. The existing studies considering path loss for WSNs on the other hand are quite conservative.The impacts of path losses are not considered, and analysed together with details in upper layers such as network and application. In this paper, a new approach is considered to combine 1 Path loss is the attenuation in power density of an electromagnetic wave as it propagates through space. the path loss related issues with packet level simulation. A case study is presented which uses path-loss as well as network and application layer data in order to predict the network lifetime. Well known path loss computation models are adopted to use with a new tool, which allows the users to deploy ensors in a two dimensional abstraction of the physical environment, and to introduce obstacles. The new tool in turn communicates with well-known Castalia package and OMNET simulation environment. The energy consumption of the nodes considering the impact of path loss for different transmission powers is presented, the tradeoff between traditional performance measures such as packet loss and residual energy is illustrated. The approach presented lends itself as a ? exible and ef? cient tool which provides a more realistic approach for analysing WSNs and evaluating the performance in terms of energy ef? iency. The ? exibility of abstraction provided for the physical environment, also makes it possible to use various path loss models (even experimental ones). The rest of the paper is organised as follows: Section II considers various types of simulators. In section III, our approach is presented. Section IV provides the details of home automation application which is chosen as a case study. Section V shows the numerical results obtained. The impact of path loss on energy consumption of the nodes in a WSN is shown as well as the behaviour of nodes for different transmission powers in presence of path losses.In section VI, conclusion and future studies are presented. II. R ELATED W ORK In this section, we consider existing simulators. They can be classi? ed based on their level of complexity in to three main categories: Instruction, algorithm and packet level. A. Instruction level simulators Instruction level simulators are often regarded as emulators. They model the CPU execution at the level of instructions. TOSSIM [8], Atemu [9], Avrora [10] are well known emulators. TOSSIM is the most commonly used emulator. However, compared to other emulators, it is not the most precise one. TOSSIM, is a platform speci? simulator (a TinyOS mote simulator) which can compile any code written for TinyOS to an executable ? le. TinyViz, is the basic GUI for TOSSIM which can visualize and interact with the running simulations. TOSSIM is speci? c for TinyOS applications on Mica motes sensors and do not include power models. Avora, is a javabased emulator used for programs speci? cally written for AVR microcontrollers produced by Amtel and the Mica2 sensor modes. Atemu provides low-level emulation of the operation of individual sensor nodes. A unique feature of Atemu is its ability to simulate a heterogeneous sensor network.It is scalable and its high ? delity platform is used as a predeployment tool for sensor networks. B. Algorithm level simulators Shawn [11], AlgoSensim [12], and Sinalgo [13], are well known algorithm level simulators with emphasis on the logic, data structure and presentation of the algorithms. They rely on some form of graphical data structure to demonstrate the communication between the nodes. Shawn is a very powerful tool in simulating large scale networks with an abstract point of view. It supports distributed protocols and generic high level algorithms. AlgoSensim focuses on network speci? analysis of algorithms like localization, distributed routing, and ? ooding. AlgoSensim mainly facilitates the implementation and quality analysis of new algorithms. Sinalgo focuses on the veri? cation of network algorithms and abstracts from the underlying layers. It also offers a message passing view of the network. Sinalgo can be employed for quick prototyping and veri? cation in freely customizable network settings. C. Packet level simulators OPNET, Qualnet, NS-2, GloMoSim, are some of the most commonly used packet level simulators. They implement the data link and physical layers in the OSI network layers.Hence, radio models, 802. 11b or newer MAC protocols, fading, collisions, noise and wave diffractions are commonly implemented. Network Simulator (NS) is a discrete event simulator written in combination of C++ and OTcl. OTcl is an object oriented scripting language, developed mainly for networking research. It provides extensive support for simulation of TCP, multicast protocols, and routing for wired and wireless networks. With protocol implementations being widely produced and developed, the extensibility of NS-2 has been a major contributor to its success.It has an object-oriented design which allows for easy creation of new protocols. The key features for WSNs include battery models, hybrid simulation support, sensor channels, scenario generation tools and a visualization tool [14]. Scalability, lack of application model and the lack of customization are few limitations of NS-2 along with lacking an application model [3]. OPNET [15] and Qualnet [16] are commercialized network simulator software with powerful standard modules and they provide good simulation environment.OPNET is an excellent choice to simulate Zigbee based networks with the implementation of Zigbee protocol and IEEE 802. 15. 4 MAC protocol. Qualnet performs well in simulating large scale sensor networks due to its scalability in wireless simulation, but OPNET simulation requires a long time when the number of sensors considered is large. The above mentioned simulators use rather simple radio/channel models [17]. Also, the simulators are still platform speci? c and moderately scalable, making them unsuitable for protocol /algorithm design and testing.Furthermore the environmental details and especially the effects of path loss has not been considered in any of the given simulation packages. III. O UR APPROACH Figure 2 outlines the main components of our approach. This has been implemented in a tool called PlaceLife. An environment editor allows the user to specify the physical environment by using a graphical editor. The environment can include different obstacles and different sensors. An obstacle can have different properties such as the material it is 570 PlaceLife other layers info Environment Editor Application Model Path loss Model Translation engine ommonly used path loss models that de? nes the behaviour of signal strength in an indoor area. The path loss behaviour is dependent on the distance between nodes and the attenuation factor added by the objects. The attenuation can vary based on several factors such as the construction materials (e. g. , wood, glass and concrete) and the object size. In the Table I we show some attenuation values in dB introduced by various materials. We provide a detailed discussion in the next Section. The dependant path loss model can be expressed as [21]: LP = L0 + 20log(d) + mtype wtype Castalia Omnet++ Fig. 2. PlaceLife here, LP represents the path loss between two nodes, d is the distance between the two nodes, L0 is the path loss in free space environment, mtype refers to the number of objects of the same type and wtype is the loss in decibels attributed to that particular object. B. The translation engine The translation engine takes as an input the environment, application, and path loss models in order to produce simulation scripts. We use Castalia [22] as a simulation tool. Castalia is a WSN simulator used for initial testing of protocols and/or algorithms with a realistic node behaviour, wireless channel and radio models.Since Castalia is highly tunable and can simulate a wide range of platforms, it is used to evaluate different platform characteristics. Castalia features an accurate radio model based on the work of the authors in [23]. It also features physical process model, considering clock drift, sensor energy consumption, CPU energy consumption, sensor bias etc. Unpredictability of the wireless channel, energy spent in transmission/receiving packets, performance degradation experienced by duty cycles, collisions are usually overlooked by simple simulators.However these details are well established in Castalia [17]. All main components that affect the energy consumption of sensor nodes are considered that are the micro-processor, the sensor module, wireless transmitter/receiver and the path loss. We emphasise that while Castalia provides a good low level simulation platform; it does not provide any means to specify the application behaviour, the environment and the path loss models. The application behaviour is needed to derive application level simulation parameters. The environment and the path loss models allow the calculation of the path loss.In fact while Castalia assumes that the user provides path loss related parameters, our approach automatically derives those values from high level models such as the environment and path loss. IV. H OME AUTOMATION Monitoring and automatic control of building environment is a case study considered quite often [24], [25], [26], [27]. Home automation can include the following functionalities: (i) heating, ventilation, and air conditioning (HVAC) systems; (ii) emergency control systems (? re alarms); (iii) centralized control lighting; and (iv) other systems, to provide comfort, energy ef? ciency and security.In order to validate our approach made of and its size. The environment editor also allows the speci? cation of the sensor position in the physical environment. Obstacles and sensor position are used to compute the path loss. An application model de? nes the behaviour of nodes. From this model various performance parameters such as transmission and sensing rates can be derived. PlaceLife considers information from other layers such as network, data and physical layers to have a more realistic approximation for the life time. At network layer different protocols such as AODV [18] and DSR [19] can be speci? d but also static routing can be de? ned. This can be easily speci? ed on the environment model. Although various data link layer access methods can be used, the Timeout MAC (T-MAC) has been chosen in this case study. T-MAC is a contention based MAC protocol that use synchronised sleep schedules between the nodes in a WSN to conserve energy [20]. Also T-MAC provides both collision avoidance and reliable transmission. A. Path loss Path loss is the attenuation in power density of an electromagnetic wave as it propagates. Path loss is consequence of many effects such as free-space loss, refraction, diffraction, re? ction, aperture-medium coupling loss, and absorption. Path loss is also affected by other factors such as propagation medium (dry or moist air), the distance between the transmitter and the receiver, and the frequency of the signal. When the effects of path loss are not considered, the evaluation of underlying structure can become optimistic, since the problems associated, retransmissions and the way this phenomena affects the energy consumption are not taken into account. In our approach a path loss model can be speci? ed by the user. This model is used together with the physical environmental model in order to de? e the path loss between two nodes. In this paper we consider indoor environment and the dependant path loss model [21]. This is one of the most 571 A5 T Sm Sp Sp A3 BS A1 T T A4 Sp Sm Sm T Sp = sprinkler T = temperature Sm = smoke BS = base station concrete wood glass Sm Sp T A2 Sp Fig. 4. Fig. 3. Home automation Energy consumed by each node with and without path loss we consider the ? re alarm system and the automatic heating application. The ? re alarm system is composed of different temperature sensors and smoke detectors that are distributed inside the building.There are also sprinkler actuators used to enable the water ? ow in case of ? re. All the temperature sensors monitor the temperature at regular intervals (every 30 seconds). When a temperature sensor reads a value that exceeds a speci? ed threshold; it sends an alert message to the smoke detector. The smoke detector receives the alert and checks for smoke. An alarm is raised when the smoke is detected. In this case the smoke sensor also activates all the sprinklers. The automatic heating application is composed of different temperature sensors, a base station and various heaters.The temperature sensors send readings every 30 seconds to the base station. This is placed at the center forming a star topology. The base station averages the readings and decides whether or not the central heating system should be on. More speci? cally the base station works in the following way: if the heating is turned on and the average temperature is greater than the minimum threshold, the central heating system turns off. if the average temperature is less than the minimum threshold, the central heating system turns on. We consider the scenario of Figure 3. A ? at composed of ? e rooms (A1-A5). We also consider different obstacles such as wooden doors, walls and glass partition. V. N UMERICAL RESULTS AND DISCUSSIONS In order to show the usefulness and effectiveness of our approach and to analyse various factors affecting the performance in terms of energy consumption of WSNs, the numerical results are presented in this section. The simulation parameters are as follows: CC2420 radio de? ned by the Texas instruments is used, the output power of the different transmission levels in dBm are varied from 0 to -25dBm. Energy consumption for each transmission level varies.For instance for 0 dBm power consumed for listening (receiving) is 62 mW and for transmission is 57. 42 mW. Packet rate is kept at 250 kbps, the radio bandwidth is 20 MHz and the simulation runs for 9000 sec. T-MAC is used as a MAC protocol, and this makes the length of each frame period for all nodes 610 milliseconds, and the duration of listen time out 61 milliseconds. For our case study, we calculated the path-loss due to the material and explicitly set our path loss map [21], [28]. Refer to Figure 3 and Table I [21] for each type of obstacle and for its contribution to path loss.For the sake of the presentation we use numbers to represent sensors. Node 0 represents the base station. Nodes 1,4,5,7, and 9 monitor temperature in areas A1,A5,A4,A3, and A2 respectively. Nodes 2,3,6, and 8 monitor smoke in the areas A1,A5,A4, and A3 respectively. Table II and Table III show the energy consumed by the nodes for the application scenario considering the path-loss phenomenon and ignoring the path loss respectively. Similarly, Figure 4 shows the difference in energy consumed by each node for two different cases. In case one path loss is ignored, and for the next set of results the path loss is present.It is evident that the lifetime of the nodes is heavily TABLE I PARTITION DEPENDENT LOSSES FOR 2. 4 G HZ obstacles Concrete wall Wooden door Glass wall Cinder wall window Brick Masonry brick metal door attenuation in dB 12 2. 8 2 4 2 5 17 12. 4 TABLE II E NERGY CONSUMED BY THE NODES IN JOULES , CONSIDERING PATH LOSS nodes 0 1 2 3 4 5 6 7 8 9 energy 100. 7 84. 9 95. 6 94. 3 90. 1 88. 8 89. 3 88. 9 90. 5 91. 2 TABLE III E NERGY CONSUMED BY THE NODES IN JOULES , IGNORING PATH LOSS nodes 0 energy 81. 4 1 2 81. 4 82. 6 3 4 5 6 7 8 9 81. 4 81. 5 81. 5 82. 7 81. 4 82. 4 83. 1 572 Fig. 5. Energy consumed vs. ransmitted power for nodes 5-9 Fig. 6. Energy consumed vs. transmitted power vs. packets lost dependent on the impact of the path loss, and ignoring the effect of path loss would be an optimistic assumption when energy consumed by each node is considered. This is because, when the effects of path loss are not considered, problems associated, retransmissions and the way this phenomena affects the energy consumption are not taken into account. However these factors affect the life time of the node. Node 3 consumes 13 joules of more energy due to path loss, when compared to no path loss.Figure 5 shows the life time of the nodes 5 to 9, considering the impact of path loss for different transmission powers. Transmission power is varied from -25 dBm to 0 dBm, the energy consumption of the nodes is increased as we increase the transmission power. For node 7, as the transmission power is increased from -25 dBm to 0dBm, the energy consumed by the node also increases from 80. 1 joules to 88. 9 joules. The trade-off between traditional performance measures such as packet loss and residual energy is presented in Figure 6.The dotted lines represent the packets lost and the straight lines represent the energy consumed by each node. As the transmission power is decreased from 0 dBm to -25 dBm, there is a gradual increase in amount of packets lost. For node 0, as the transmission power is decreased from 0 dBm to -25 dBm, the number of packets lost increases to 370, from 206 and the energy consumed increases to 100 joules, from 88 joules. Because of the retransmissions, more energy is consumed by the nodes. But the increase in transmission power does not necessarily mean increase in the life time as there are no retransmissions.When the tradeoff between the packet loss and the energy consumed is analysed, it can be seen that the optimum transmission power should be between -15 to -5 dBm where the energy consumption is less than 95 joules and packet loss is less than 200 packets. VI. C ONCLUSION AND FUTURE WORK In this paper, a simulation-based study is presented that uses path-loss network and application layer data in order to predict the network lifetime. Physical environment is considered as well. 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