Building a Wireless Sensor Network Essay Example for Free (#6)

Building a Wireless Sensor Network Essay 1.0 Introduction In the previous era, the technology application mostly using wire but now a wireless device has become common place. The definition of wireless sensor network is an application that having no wires connection on that devices. In addition, to make the system easy to monitor from a distant location, the RF 433MHz module was used. So, this project gave rise to the idea for studying details about the RF 433MHz module performance for WSN application. 1.1 Project Background Nowadays, using the wireless sensor network (WSN) technology to monitor the environment helps someone to solve the problems of deployment difficulty, high cost, and realized unmanned monitoring which is mostly used in factory, buildings, laboratory and house. This project is to study the range and performance of the RF 433MHz module for WSN application. RF 433MHz module are popular used in remote control system. This range also available to use in this area. There are two types of the RF module which is transmitter and receiver. From research, using RF 433MHz module, the data can get more accurately without any data losses with the range that given than compared to other transmission for wireless sensor network. The range that can reach by this RF module is different between outside and inside area. For inside area, it can work for 50 meters through multiple walls with an antenna, while for the outside area, it will be able for hundreds of meters. Besides that, a microcontroller such as Arduino also used in this project. Arduino that available for this project is Arduino PRO which is it has 3.3V port that will be easier to connect directly to the types of RF 433MHz module that used in this project. This project also will be studied the analysis of the data transmission by giving a few of distance between the transmitter and receiver of the RF 433MHz modules when located in the obstacles or line of sight area. Then, the data that are received will be displayed on the computer whether there are data losses or not. 1.2 Problem Statement The problem that becoming as issues right now is there is a lot of ways to send data but the problem is about the range, cost, and data losses. So, for this situation, study the performance of RF 433MHz can overcome the problem for the WSN application. The objectives of this project are to understand the range and performance of RF 433MHz module. Moreover, exploration about the transmitting and receiving the data by using the RF 433MHz module. 1.4 Work Scope The main work scope of this project is to make sure this project will achieve the objectives. The main focus of this project:- i. To study and understanding the range of RF 433MHz module. ii. To transfer data by using RF 433MHz module. 1.5 Methodology In this project, there are three main parts. For the first part, it will be focused on the conducting the literature review and do some research more detail about the RF 433MHz module. Meanwhile, for the second part, after the software development process, the hardware development process will take over and include the testing of the project. Last part, when the hardware and software complete their part, it will be followed by testing the performance and the operation of the project to make an analysis. 1.6 Report Structure This part will explain all the flow for completing this report and project. In this report, there are five chapters. Chapter 1: Introduction This chapter will introduce the background of the project, state the problems, clear about the objectives, scope of work, planned the methodology and structure of report to make it organized. Chapter 2: Literature Review This chapter will be explained more details about all the research that have been done. Then, the summarization for the project also will be attached to this chapter to make it clear. Chapter 3: Methodology The methodology is the procedures or steps when doing this project. The simulation, analysis, and evaluation of the project will be discussed in this chapter. This method is important because from here the flow of the process for the project will be updated. Chapter 4: Expected Results The expected results in the software or hardware will be stated in this chapter. The comparisons and improvements of this project will be described here. Analysis of the results also will be discussed here. Chapter 5: Conclusion In this chapter, to make a conclusion for all the summary of this project was collected in each part can be discussed in the conclusion. Building a Wireless Sensor Network. (2018, Apr 18). We have essays on the following topics that may be of interest to you

Knowledge management Essay Example | Topics and Well Written Essays - 500 words

Knowledge management - Essay Example Knowledge management theorists categorize tacit and explicit knowledge. Using simulation, graphs, games and other materials will be part of explicit knowledge, which relates to the use of knowledge or information stored in a data base, games etc. As Wiig (2004, p. 98) noted, making use of stories, simulation and games for knowledge management essentially requires that the recipients must have sufficient background and prior knowledge. Games, simulation, calculation, recreation, graphical representation are some of the techniques and strategies that can be used for creating knowledge, sharing it between people, transferring it from one group to the other and making use of it for the overall benefits of organization. In using or depending on gaming, simulation and other tools for knowledge management, computer or any other electronic media can be used for storing information in useable data base, converting them to more convenient forms and getting them highly useful for the organizati onal requirements. The main techniques to be used for this purpose include maintaining accuracy, reliability, dependability and flexibility etc.

I don't have one, thats my problem Should be a topic that deals Research Paper

I don't have one, thats my problem Should be a topic that deals broadly with a problem with educational purposes within american society - Research Paper Example We begin with an overview of the controversies surrounding standardized testing in a modern context and evaluate these controversies with an eye to how educators can learn from the issues at hand. We explore the issue of race and standardized testing and discern whether or not standardized testing is the best means through which student evaluation is undertaken. From this perspective, the historical and sociopolitical issues surrounding standardized testing in America are brought to the fore. Controversy surrounding the implementation of standardized testing can be found throughout the United States. Does a uniform, standardized test accurately reflect a student’s educational aptitude, learning history and future academic performance? As mentioned above, standardized testing is quite common in the United States as the SAT remains a near universal experience for high school students across the country aiming to get into the universities and colleges of the choice. The issue of standardized testing is relatively recent worldwide and remains embroiled in controversy. Presently, Canadian universities do not require a standardized test for admittance although many graduate school programs do. These include the GMAT or LSAT for law school applications. Presently, Montreal’s McGill University is the only English-language law school in North America which does not require an LSAT score for admittance. As the issue of standardized testing came to the fore, a Septemb er 2005 poll by the College of Teachers found that 71% of teachers were â€Å"dead set against standardized testing†. In a survey from 2004, Teachers vehemently oppose the use of standardized tests as a means to evaluate staff or schools or to decide how money is allocated to schools or school boards. The public disagrees. For example, 79 per cent of teachers oppose using provincial tests to

The Power of Biofeedback Essay -- Biology Essays Research Papers

Mind Over Matter: The use of Biofeedback to control stress, pain, and other bothersome problems Having a bad day? Well, I am. I have too much work to do, like always, but I want and have to graduate. I think I'm happy about that, about putting an end to all the pressure I have felt in these last four years. Then again I am not sure what to think. I will miss my friends, especially all those people with whom I was briefly acquainted and liked enough to sense the possibility of friendship but will never know now. On top of these worries are more general fears of the uncertainty of the next few years, not to mention the rest of my life. Going home to a place I've never really liked simply because I can't think of anything better to do scares me; the possibility of getting stuck there scares me even more. I need to find a job. I need to find a career. I want to go to graduate school at some point, but my grades after this semester will not make admission easy. Needless to say, there is a lot on my mind. This morning I went in for a doctor's appointment, just a quick check-up becaus e I've been sick. As is routine, the nurse took my blood pressure. Then she turned and frowned at me. Seems that the pressure I'm under is not just weighing down on my mind. My body is responding to my higher level worries by sending my blood slamming through me with alarming force. We like to think of stress as a purely higher level function which only effects us on that level, and generally ignore the effects it might have on us on a more biological as opposed to psychological level, i.e. on the level of our voluntary and autonomic response systems. We hear Doctors on TV and DJs on NPR warning us that stress can kill, but we disregard them until we see ... ...y and promise of a more complete understanding of just what our minds can do. Perhaps the nurseÕs frown is a needed wake up call. I may feel like my life is out of control, but the one thing I always do is think positive. It will not only improve my mental state, but my physical well being as well. Besides, things are looking up; I've just finished another paper. References: From Medline: (1) www.healthy.net (2) www.healthy.net/hwlibraryarticles/biofeedback/biofeedbackwhatis.htm (3) www.healthy.net/hwlibraryarticles/mindbodyconnectio/mbbiofeed.htm (4) www.healthy.net/hwlibrarybooks/mind.htm From Neuroguide: (5) www.aapb.org/index.htm (6) www.biof.com/biofeedbackdef.html (7) www.biof.com/lsfaq.html (8) freud.tan.ac.il/~biosee/msr.html (9) freud.tan.ac.il/~biosee/defin.html (10) freud.tan.ac.il/~biosee/prob.html The Power of Biofeedback Essay -- Biology Essays Research Papers Mind Over Matter: The use of Biofeedback to control stress, pain, and other bothersome problems Having a bad day? Well, I am. I have too much work to do, like always, but I want and have to graduate. I think I'm happy about that, about putting an end to all the pressure I have felt in these last four years. Then again I am not sure what to think. I will miss my friends, especially all those people with whom I was briefly acquainted and liked enough to sense the possibility of friendship but will never know now. On top of these worries are more general fears of the uncertainty of the next few years, not to mention the rest of my life. Going home to a place I've never really liked simply because I can't think of anything better to do scares me; the possibility of getting stuck there scares me even more. I need to find a job. I need to find a career. I want to go to graduate school at some point, but my grades after this semester will not make admission easy. Needless to say, there is a lot on my mind. This morning I went in for a doctor's appointment, just a quick check-up becaus e I've been sick. As is routine, the nurse took my blood pressure. Then she turned and frowned at me. Seems that the pressure I'm under is not just weighing down on my mind. My body is responding to my higher level worries by sending my blood slamming through me with alarming force. We like to think of stress as a purely higher level function which only effects us on that level, and generally ignore the effects it might have on us on a more biological as opposed to psychological level, i.e. on the level of our voluntary and autonomic response systems. We hear Doctors on TV and DJs on NPR warning us that stress can kill, but we disregard them until we see ... ...y and promise of a more complete understanding of just what our minds can do. Perhaps the nurseÕs frown is a needed wake up call. I may feel like my life is out of control, but the one thing I always do is think positive. It will not only improve my mental state, but my physical well being as well. Besides, things are looking up; I've just finished another paper. References: From Medline: (1) www.healthy.net (2) www.healthy.net/hwlibraryarticles/biofeedback/biofeedbackwhatis.htm (3) www.healthy.net/hwlibraryarticles/mindbodyconnectio/mbbiofeed.htm (4) www.healthy.net/hwlibrarybooks/mind.htm From Neuroguide: (5) www.aapb.org/index.htm (6) www.biof.com/biofeedbackdef.html (7) www.biof.com/lsfaq.html (8) freud.tan.ac.il/~biosee/msr.html (9) freud.tan.ac.il/~biosee/defin.html (10) freud.tan.ac.il/~biosee/prob.html

Babies Behind Bars

The rate of women being incarcerated in prisons has dramatically risen over the last decade. While these women are being locked up for crimes ranging from drug possession to murder, they often come into the prison system with children or pregnant. Nationwide, nearly 2 million children have parents in prison. The number of those with incarcerated mothers is growing rapidly. A recent report from the Bureau of Justice Statistics found that the number of minors with mothers in prison increased by more than 100 percent in the last 15 years [ (Schwartzapfel, 2008) ].While some women must give up their children before or after they enter prison, a handful of women get to keep their children. These women serve their sentences at one of nine prisons that have prison nurseries. However, not all women are afforded this privilege which comes with strict qualifications. A prison nursery is a program that allows a child born to an incarcerated women to remain in the care of its mother for a restri cted amount of time within a correctional facility [ (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009) ].Prison nurseries in the United States are only open to mothers who give birth to their children while they are serving their sentence. Prison nurseries are not fairly new to the United States. In the 1950s, many women's prisons had nurseries in which infants could stay with their mothers from several weeks to two years, depending on the institution. Within two decades, every state except New York closed them. The nurseries were deemed too expensive, the mothers too ruined and the babies too precious for such an environment [ (Kauffman, 2001) ].The only program left operating was at the Bedford Hills Correctional Facility for Women in Bedford Hills, New York. The Bedford Hills Correctional Facility, which is a maximum security facility, has the oldest prison nursery in the United States. Opening its doors in 1901, the pr ogram is also the largest, having space for 29 mother/infant pairs. Women live with their babies in bright rooms stuffed with donated toys and clothes.During the day, while the women attend DOC-mandated drug counseling, anger management, vocational training and parenting classes, their children attend a day care staffed by inmates who have graduated from an intensive two-year Early Childhood Associate vocational training program (Schwartzapfel, 2008). Qualifications to participate in the program are stringent. Several aspects of a woman’s past are examined before she can participate in the nursery.This includes determining who is going to have custody of the child, if the mother has a history of involvement with the child-welfare system, the length of her sentence, past episodes of incarceration, and the nature of her crime. Women who have committed arson or who have a history of child abuse are not eligible for the nursery. At Bedford Hills the infant can stay for up to 18 m onths if the mother will be paroled by then, otherwise the child must leave the facility at 12 months of age (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009).There are currently prison nursery programs in nine states: California, Illinois, New York, Nebraska, Washington, Ohio, Indiana, South Dakota, and West Virginia. Many of these programs started within the last few years. These programs are relatively rare and focus on the concept of the bond formed between mother and child within the first two years of life. Taconic Correctional Facility, also located in Bedford Hills, New York, was the second facility to host a prison nursery program. Opening in 1990, it models the first program; the qualifications and length of stay for infants are similar.However, Taconic only houses 15 mother/infant pairs. Nebraska opened its prison nursery program in 1994. The Nebraska Correctional Center for Women, located in York, Nebraska, hol ds 15 mother/infant pairs. Infants are allowed to stay up to 18 months in the Parenting Program. To participate in the nursery the mother must give birth while in state custody and not have a violent criminal record. She also should not have any serious mental health concerns. A screening committee reviews each case before women are placed in the nursery.The mother must be able to complete her sentence by the time the child is 18 months old to be eligible (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009). Four years later, Pierre, South Dakota opened its prison nursery in the South Dakota Women’s Prison. The Mother-Infant Program is the only prison nursery that doesn’t have a limit to how many infants can stay. However, it has the shortest length of stay being thirty days. Women who give birth while in custody are allowed to participate in the program as long as the mother's crime was non-violent in nature.Al l expenses related to the baby's care are the responsibility of the mother, including health care expenses. Mothers keep their infants in their cells. Other women at the facility are able to take classes to become babysitters and the mothers are able to choose who they would like to act as their babysitter. The Washington Correctional Center for Women in Gig Harbor, Washington, opened its doors to a prison nursery in 1999. To qualify for the Residential Parenting Program, the mother’s sentence must be completed within three years of giving birth. The women must also be classified as minimum custody and be convicted of a non-violent offense.The program houses 20 mother/infant pairs and allows the infants to stay up to 36 months (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009). Marysville, Ohio implemented its prison nursery at the Ohio Reformatory for Women in 2001. The program houses 20 mothers and up to 21 infants . Infants stay for a maximum of 18 months. To qualify for the Achieving Baby Care Success Program, women must give birth while in state custody and cannot have a violent criminal record. Women must attend family training courses, adhere to rules and be in good mental and physical condition.Only women who are serving a sentence of 18 months or less at the time of delivery are eligible. The Moms and Babies Program at Decatur Correctional Center in Decatur, Illinois started in 2007. The capacity for the program is 5 mother/infant pairs with infants staying up to 24 months. A woman must have committed a non-violent offense and be within two years of release after giving birth (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009). The more recent nursery programs were started in the last four years.Indiana, California, and West Virginia were the last states of the nine to implement prison nurseries. Because the programs are newer, various changes are still being made. In 2008, Indiana Women’s Prison, in Indianapolis, Indiana, established its prison nursery. The Wee Ones Nursery Program houses 10 mother/infants pairs and 4 nannies. To participate in the program the child must be born in custody and the mother must be eligible for release by the time the child is 18 months old. Mothers and nannies who have been convicted of child abuse or a violent crime are not eligible to participate. The final two prison nurseries started in 2009.Corona, California started its Mother-Child Reunification Program at California Institution for Women. The program can hold up to 16 women: 10 with infants and 6 who are pregnant. Like most programs, the infants stay up to 18 months. After women spend up to 18 months in the nursery they will be transitioned onto parole or into a community-based program such as the Community Prison Mothers Program. In addition to the planned nursery, the facility runs a child-visiting program and mother-father mediation program. All pregnant women are placed in this institution and other women can request to be sentenced or transferred here.West Virginia’s Lakin Correctional Center for Women, located in West Columbia, has the KIDS Unit program. KIDS, Keeping Infant Development Successful, is available to pregnant women who are within 18 months of release or parole. The nursery is made up of modular homes located outside the prison’s perimeter fence. To participate in the nursery the mother must not have been convicted of a sex crime or a crime against a child and must be free of disciplinary write-ups (Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative, 2009).Many experts believe that prison nurseries increase the bond between mother and child and lowers recidivism rates. Chandra Villanueva, Policy Associate at WPA and author of the report commented, â€Å"Prison nursery programs keep mothers and infants together during the critical first months of infant development, and the research shows that these programs produce lower rates of recidivism among participating mothers. † (Women's Prison Association, 2009).Researchers studying prison nurseries found that â€Å"infants who lived with their mothers for a year or more in the prison nursery program were significantly more likely to be securely attached in spite of their mothers’ insecurity than those who were released earlier. † â€Å"Development of an attachment relationship is a long and fragile process and requires ongoing supports for mothers raising infants in prison nurseries, for future alternate caregivers living in the community, and for the children who will ultimately experience a multitude of environmental risks. † (Byrne, Goshin, & Joestl, 2010).On the other hand, some believe that babies don’t belong in prison, for their primary role is punishment and rehabilitation. Not to mention that the programs are expensive, averaging about $24,000 a year per infant (Schiavocampo, 2010). As the number of incarcerated women continues to grow, we can expect to see the number of prison nurseries growing as well. Because the programs have been deemed successful, other states may start implementing them into their prison systems. This gives the mother some form of responsibility while she is incarcerated without separating her from the child.However, we should focus more on keeping women out of prison than creating more nurseries. Bibliography Byrne, M. , Goshin, L. , & Joestl, S. (2010). Intergenerational transmission of attachment for infants raised in a prison nursery . Attachment and Human Development, 375-393. Kauffman, K. (2001). Mothers in Prison. Corrections Today, 62-65. Mothers, Infants and Imprisonment: A National Look at Prison Nurseries and Community-Based Alternative. (2009, May). Retrieved from Women's Prison Association : http://www. wpaonline. rg/pdf/Mothers%20Inf ants%20and%20Imprisonment%202009. pdf. Schiavocampo, M. (2010, April 13). Reporter's notebook: A look at babies behind bars. Retrieved from The Grio: http://thegrio. com/2010/04/13/reporters-notebook-a-look-at-babies-behind-bars/. Schwartzapfel, B. (2008). Lullabies Behind Bars. Retrieved from Ms. Magazine: http://www. msmagazine. com/Fall2008/LullabiesBehindBars. asp. Women's Prison Association. (2009, July 13). Prison Nursery Programs a Growing Trend in Women’s Prisons. Retrieved from Corrections. com: http://www. corrections. com/news/article/21644.

The Cold War Was A War Based On Ideologies - 1845 Words

AAfter the end of World War II, the world was split into two -- East and West. This marked the beginning of the era called the Cold War The Cold War was a war based on ideologies. The United States of America representing freedom and democracy and Russia representing order and socialism. These separated ideals is what started the deadliest competition in history, where both sides gathered intelligence on how other side was progressing and used that information as leverage against the other, this is known as Espionage. Espionage by definition is â€Å"The practice of spying or of using spies, typically by governments to obtain political and military information†. This documentary will uncover the phenomenon of the cold war that is more†¦show more content†¦Project QKHILLTOP was the starting point in US affairs in mind control and neural research, this would help them in the growing battle of communism in America and allow them to control the minds of their enemies. The US obtained the idea during the Korean War when Chinese Soldiers, used brainwashing techniques to convert enemy US soldiers the method is a states: Assault on Identity Attacks on one s sense of belief and self, under constant brutal verbal assault for days, weeks and months at a time. 2. Guilt Making one feel bad attacking them constantly. 3. Self Betrayal Agreeing you are bad or not good. Once in guilt the Chinese soldier, forces the US soldier through physical or mental harm. To his family and friends that they are doing bad also. 4. Breaking Point The US soldier at this stage suffers questions one humanity and begins to completely break away and lose sanity. The US after the war becoming aware of these so called â€Å"mind control† techniques came to the conclusion that this method was to time intensive, so with the help of modern day sedatives, alcohol and drugs the US eventually completed their research, but the price was US lives with some even committing suicide. Therefore America s conduct of espionage during the Cold war similar to that of Russian espionage, when trying

Why Trenches Were Used in World War I

During trench warfare, opposing armies conduct battle, at a  relatively close range, from a series of ditches dug into the ground. Trench warfare becomes necessary when two armies face a stalemate, with neither side able to advance and overtake the other. Although trench warfare has been employed since ancient times, it was used on an unprecedented scale on the Western Front during World War I. Why Trench Warfare in WWI? In the early weeks of the First World War (late in the summer of 1914), both German and French commanders anticipated a war that would involve a large amount of troop movement, as each side sought to gain or defend territory. The Germans initially swept through parts of Belgium and northeastern France, gaining territory along the way. During the First Battle of the Marne in September 1914, the Germans were pushed back by Allied forces. They subsequently dug in to avoid losing any more ground. Unable to break through this line of defense, the Allies also began to dig protective trenches. By October 1914, neither army could advance its position, mainly because war was being waged in a very different way than it had been during the 19th century. Forward-moving strategies such as head-on infantry attacks were no longer effective or feasible against modern weaponry such as machine guns and heavy artillery. This inability to move forward created the stalemate. What began as a temporary strategy evolved into one of the main features of the war at the Western Front for the next four years. Construction and Design of Trenches Early trenches were little more than foxholes or ditches, intended to provide a measure of protection during short battles. As the stalemate continued, however, it became obvious that a more elaborate system was needed. The first major trench lines were completed in November 1914. By the end of that year, they stretched 475 miles, starting at the North Sea, running through Belgium and northern France, and ending in the Swiss frontier. Although the specific construction of a trench was determined by the local terrain, most were built according to the same basic design. The front wall of the trench, known as the parapet, was about 10 feet high. Lined with sandbags from top to bottom, the parapet also featured 2 to 3 feet of sandbags stacked above ground level. These provided protection, but also obscured a soldiers view. A ledge, known as the fire-step, was built into the lower part of the ditch and allowed a soldier to step up and see over the top (usually through a peephole between sandbags) when he was ready to fire his weapon. Periscopes and mirrors were also used to see above the sandbags. The rear wall of the trench, known as the parados, was lined with sandbags as well, protecting against a rear assault. Because constant shelling and frequent rainfall could cause the trench walls to collapse, the walls were reinforced with sandbags, logs, and branches. Trench Lines Trenches were dug in a zigzag pattern so that if an enemy entered the trench, he could not fire straight down the line. A typical trench system included a line of three or four trenches: the front line (also called the outpost or the fire line), the support trench, and the reserve trench, all built parallel to one another and anywhere from 100 to 400 yards apart. The main trench lines were connected by communicating trenches, allowing for the movement of messages, supplies, and soldiers and were lined with barbed wire. The space between the enemy lines was known as No Mans Land. The space varied but averaged about 250 yards. Some trenches contained dugouts below the level of the trench floor, often as deep as 20 or 30 feet. Most of these underground rooms were little more than crude cellars, but some, especially those farther back from the front, offered more conveniences, such as beds, furniture,  and stoves. The German dugouts were generally more sophisticated; one such dugout captured in the Somme Valley in 1916 was found to have toilets, electricity, ventilation, and even wallpaper. Daily Routine in the Trenches Routines varied among the different regions, nationalities, and individual platoons, but the groups shared many similarities. Soldiers were regularly rotated through a basic sequence: fighting in the front line, followed by a period in the reserve or support line, then later, a brief rest period. (Those in reserve might be called upon to help the front line if needed.) Once the cycle was completed, it would begin anew. Among the men in the front line, sentry duty was assigned in rotations of two to three hours. Each morning and evening, just before dawn and dusk, the troops participated in a stand-to, during which men (on both sides) climbed up on the fire-step with rifle and bayonet at the ready. The stand-to served as preparation for a possible attack from the enemy at a time of day—dawn or dusk—when most of these attacks were likeliest to occur. Following the stand-to, officers conducted an inspection of the men and their equipment. Breakfast was then served, at which time both sides (almost universally along the front) adopted a brief truce. Most offensive maneuvers (aside from artillery shelling and sniping) were carried out in the dark when soldiers were able to climb out of the trenches clandestinely to conduct surveillance and carry out raids. The relative quiet of the daylight hours allowed men to discharge their assigned duties during the day. Maintaining the trenches required constant work: repair of shell-damaged walls, removal of standing water, the creation of new latrines, and the movement of supplies, among other vital jobs. Those spared from performing daily maintenance duties included specialists, such as stretcher-bearers, snipers, and machine-gunners. During brief rest periods, soldiers were free to nap, read, or write letters home, before being assigned to another task. Misery in the Mud Life in the trenches was nightmarish, aside from the usual rigors of combat. Forces of nature posed as great a threat as the opposing army. Heavy rainfall flooded trenches and created impassable, muddy conditions. The mud not only made it difficult to get from one place to another; it also had other, more dire consequences. Many times, soldiers became trapped in the thick, deep mud; unable to extricate themselves, they often drowned. The pervading precipitation created other difficulties. Trench walls collapsed, rifles jammed, and soldiers fell victim to the much-dreaded trench foot. Similar to frostbite, trench foot developed as a result of men being forced to stand in water for several hours, even days, without a chance to remove wet boots and socks. In extreme cases, gangrene would develop and a soldiers toes, or even his entire foot, would have to be amputated. Unfortunately, heavy rains were not sufficient to wash away the filth and foul odor of human waste and decaying corpses. Not only did these unsanitary conditions contribute to the spread of disease, they also attracted an enemy despised by both sides—the lowly rat. Multitudes of rats shared the trenches with soldiers and, even more horrifying, they fed upon the remains of the dead. Soldiers shot them out of disgust and frustration, but the rats continued to multiply and thrived for the duration of the war. Other vermin that plagued the troops included head and body lice, mites and scabies, and massive swarms of flies. As terrible as the sights and smells were for the men to endure, the deafening noises that surrounded them during heavy shelling were terrifying. Amid a heavy barrage, dozens of shells per minute might land in the trench, causing ear-splitting (and deadly) explosions. Few men could remain calm under such circumstances; many suffered emotional breakdowns. Night Patrols and Raids Patrols and raids took place at night, under cover of darkness. For patrols, small groups of men crawled out of the trenches and inched their way into No Mans Land. Moving forward on elbows and knees toward the German trenches and cutting their way through the dense barbed wire on their way. Once the men reached the other side, their goal was to get close enough to gather information by eavesdropping or to detect activity in advance of an attack. Raiding parties were much larger than patrols, encompassing about 30 soldiers. They, too, made their way to the German trenches, but their role was more confrontational. Members of the raiding parties armed themselves with rifles, knives, and hand grenades. Smaller teams took on portions of the enemy trench, tossing in grenades, and killing any survivors with a rifle or bayonet. They also examined the bodies of dead German soldiers, searching for documents and evidence of name and rank. Snipers, in addition to firing from the trenches, also operated from No Mans Land. They crept out at dawn, heavily camouflaged, to find cover before daylight. Adopting a trick from the Germans, British snipers hid inside O.P. trees (observation posts). These dummy trees, constructed by army engineers, protected the snipers, allowing them to fire at unsuspecting enemy soldiers. Despite these strategies, the nature of trench warfare made it almost impossible for either army to overtake the other. Attacking infantry was slowed down by the barbed wire and bombed-out terrain of No Mans Land, making the element of surprise unlikely. Later in the war, the Allies did succeed in breaking through German lines using the newly-invented tank. Poison Gas Attacks In April 1915, the Germans unleashed an especially sinister new weapon at Ypres in northwestern Belgium: poison gas. Hundreds of French soldiers, overcome by deadly chlorine gas, fell to the ground, choking, convulsing, and gasping for air. Victims died a slow, horrible death as their lungs filled with fluid. The Allies began producing gas masks to protect their men from the deadly vapor, while at the same time adding poison gas to their arsenal of weapons. By 1917, the box respirator became standard issue, but that did not keep either side from the continued use of chlorine gas and the equally-deadly mustard gas. The latter caused an even more prolonged death, taking up to five weeks to kill its victims. Yet poison gas, as devastating as its effects were, did not prove to be a decisive factor in the war because of its unpredictable nature (it relied upon wind conditions) and the development of effective gas masks. Shell Shock Given the overwhelming conditions imposed by trench warfare, it is not surprising that hundreds of thousands of men fell victim to shell shock. Early in the war, the term referred to what was believed to be the result of an actual physical injury to the nervous system, brought about by exposure to constant shelling. Symptoms ranged from physical abnormalities (tics and tremors, impaired vision and hearing, and paralysis) to emotional manifestations (panic, anxiety, insomnia, and a near-catatonic state.) When shell shock was later determined to be a psychological response to emotional trauma, men received little sympathy and were often accused of cowardice. Some shell-shocked soldiers who had fled their posts were even labeled deserters and were summarily shot by a firing squad. By the end of the war, however, as cases of shell shock soared and came to include officers as well as enlisted men, the British military built several military hospitals devoted to caring for these men. The Legacy of Trench Warfare Due in part to the Allies use of tanks in the last year of the war, the stalemate was finally broken. By the time the armistice was signed on November 11, 1918, an estimated 8.5 million men (on all fronts) had lost their lives in the so-called war to end all wars. Yet many survivors who returned home would never be the same, whether their wounds were physical or emotional. By the end of World War I, trench warfare had become the very symbol of futility; thus, it has been a tactic intentionally avoided by modern-day military strategists in favor of movement, surveillance, and airpower.