Failed IT Project Research Paper Example | Topics and Well Written Essays - 1250 words

Failed IT Project - Research Paper Example IT project teams emphasize on developing software using unsophisticated codes that would facilitate its functionality. Simplicity facilitates the ease of implementation of the project. In addition, monitoring the functionality of the project is far much easier (Smite, Agerfalk & Moe, 1998). Thus, a project that emphasizes on the complexity from the outset will ultimately faces many difficulties in its design and implementation. It was evident that the complexity of the baggage handling system would lead to enormous problems in implementation and design. The system was too complex that the programmers had to develop it in two years. In fact, it was the most complex baggage handling system ever developed. This was because the system would serve a mammoth airport that was twice the size of Manhattan that had more than 20 major airlines. In designing complex systems, it is vital that the complexity of the systems is manageable during the not only during its development but also in its ma intenance. However, the BAE engineers designed a system that had high coupling and had widespread and inconsistent points of failure (Kerzner, 2004). This led to many problems during the testing of the system. In designing complex IT projects, the engineers must ensure that there is modularity in the operations. Modularity makes complexity of the projects manageable. In addition, it facilitates the undertaking of parallel work and accommodates future uncertainties. In projects with modular architecture, substitution of new designs with older ones is relatively cheap. (Liso, 2009). However, in undertaking the automation of the DIA ABS there was not modularity in the activities of the project. Lack of modularity posed serious problems especially after DIA and BAE changed the design of the system to accommodate the requests made by the airline companies. Lack of modularity led to faults that were evident during the testing of the system in the media's presence. Telecars crushed into each other and flung the baggage spewing out the contents of the baggage (Kock, 2006). In

Assignment 2 Example | Topics and Well Written Essays - 1500 words - 1

2 - Assignment Example 7. The researchers excluded persons from the study who had a history of psychiatric illness. Provide a rationale for excluding these persons. Basically, the experiment was aimed at finding the best treatment for depression. Therefore, having an earlier treatment for psychiatry may affect the results of the experiment. 2. What statistics were used to describe the demographic variable Estimated Yearly Family Income in this study? Were these appropriate? Employment and the socioeconomic status were used for measuring the yearly family income in this study. However, these were not the appropriate measures. Non parametric statistical analysis techniques are the best fit for education. Parametric tests are done for data whose variances are homogeneous. However, this is not the case for education and therefore, non-parametric tests are best for education. 9. Are there significant differences between the intervention and the control groups for any of the variables in Table I? Provide a rationale for your answer. From the table, there are no significant differences between the intervention and the control groups. This is because there are no significant differences in the percentages of the control groups and the intervention group. 6. Explain why the number of total subjects’ data in Table 2 is for 859 subjects when the total sample for the study was 869 subjects. The people who had a history of cardiac attacks earlier were excluded from the experiment. This study and its results cannot be generalized for the United States. This is because the sample was not representative. The sample was only selected in the rural areas and the sample size was not sufficient, therefore does not reflect the condition in the United States. 1. The following list represents the number of nursing students enrolled in a particular nursing program between the years of 2001 and 2007, respectively: 563, 593, 606, 520, 563, 610, and 577. Determine the mean,

Processes of Polyadenylation

Processes of Polyadenylation DNA once transcribed into mRNA it is transported to the cytoplasm. All mRNA’s including specific unspliced mRNA precursors contain the poly A tail with histon mRNA as an exception. But once they are transported to the cytoplasm there exist a poly (A) tail shift that is brought about by the degradation by RNases and rebuilding by cytoplasmic poly (A) polymerase. Discovery: James Darnell and his coworkers carried out various experiments to study and understand the process of polyadenylation. To begin with, they concentrated on the isolation of the poly (A) tail from the newly synthesized mRNA of the HeLa cell line using two subtypes of the enzyme RNase. The enzymes were; 1. RNase A which function as nucleases that cut after the pyrimidine nucleotides C and G and 2. RNase T1 which cuts after G nucleotides. Both these enzymes together helped in selection of pure runs of A’s. They then carried out centrifugation to separate the nucleus and cytoplasm to separate them according to their sizes and exposed them to the scintillation counter. The results obtained showed that both peaks of the nucleus and cytoplasm electrophoresed even slower than the 4S-tRNA and 5S-rRNA markers used (size markers). It also confirms the little difference in size that exist between the nuclear and cytoplasmic mRNA poly (A)’s. Position confirmation: To confirm the 3-prime position of the poly (A) tail they subjected mRNA to an enzyme RNase. On complete digestion it yielded one molecule of adenosine and about 200 molecules of AMP. This result also aided in concluding the size of the poly (A) tail to be about 200 nucleotides long but recent advances and studies have confirmed the size of the poly (A) tail to be about 250nt long. Activity of poly (A) polymerase: Furthermore it had to confirmed that the poly A tail hadn’t come from DNA transcription as the DNA doesn’t contain long runs of T’s. Therefore being a post transcription modification it stresses on the activity of the poly (A) polymerase that adds AMP residues one at a time to the mRNA synthesized during the transcription process. This can be confirmed with the use of actinomycin D that inhibits DNA-directed transcription but doesn’t inhibit polyadenylation. Role of the poly (A) tail: 1. Protects mRNA from degradation – Michel Revel and his colleagues studied the same by injecting globin mRNA with and without poly A tail into Xenopus oocyes and measured the rate of its synthesis at various intervals. They found a little difference at first but after 6 hours only the mRNA without the poly (A) tail couldn’t support translation. The simplest explanation they gave regarding the same was that the mRNA with the poly (A) tail had a longer shelf life therefore its protective in nature. 2. Stimulates translation of the attached mRNA- Poly (A)-binding protein (PAB 1) in eukaryotes boost the efficiency of the mRNA translation. This is confirmed by the invitro experiment that contained a capped and poladenylated mRNA excess poly (A) tails. When comparing with the control that lacked the excess poly (A) tails lower rates of translation was observed. This suggested that the free poly (A) tails competed with the poly (A) tails on the mRNA. Another control confirmed that in the absence of the mRNA the transciption rates were very low as it can’t bind to PAB1 efficiently. David Munroe and Allan Jacobson studied the effect of both capping and polyadenylation on the transcription of two synthetic mRNA’s(rabbit ÃŽ ² globin gene-RBG and vesicular stomatitis virus N gene –VSN.N under the influence of phage SP6 promoter) in rabbits reticulocytes. a) Polysome profi les. Munroe and Jacobson mixed  32P-labeled poly(A)1 (blue) and 3H-labeled poly(A)2 (red) mRNA with a  rabbit reticulocyte extract, then separated polysomes from monosomes by sucrose gradient ultracentrifugation. The arrow  denotes the monosome peak; fractions to the left of this peak are  polysomes, and one can see the disome, trisome, and even higher  polysome peaks. The poly(A)1 mRNA is clearly better at associating  mRNA stability and translatability. The Basic Mechanism: Polyadenylation is assumed to occur either at the 3à ¡Ã‚ ¿Ã‚ ½-end of the primary transcript synthesized or at the polyadenylation site upsteam to the last coding site of the transcript. But polyadenylation begins even before the transcripts is synthesized as it involves a pre-transcriptional step of clipping of mRNA and then adding poly(A) tail to the newly exposed 3à ¡Ã‚ ¿Ã‚ ½-end. Thus the RNA polymerase can still be functioning as somewhere upstream the polyadenylation apparatus has already located a signal which can cut the mRNA upstream and polyadenylate it. Nevins and Darnell eliminated the first hypothesis by creating hybrids of radioactive RNA made in cells late in infection to DNA fragments of the major late region. If transcription halted at the first few genes after the first polyadenylation sites then much more transcripts would bind to the 5à ¡Ã‚ ¿Ã‚ ½-end rather than the 3à ¡Ã‚ ¿Ã‚ ½-end of the major late region. But it was seen that the RNA hybridized equally to both the ends confirming that once the transcription of the late gene has begun it runs all the way as there is only one transcription terminator at the end of the gene. Thus this region can be called as a transcription unit due to its ability to be transcribed as a whole though it contains multiple genes. They also went on to confirm the clipping of the mRNA pre translation. Erhard Hofer and James Darnell isolated labeled globin encoding RNA that was induced by dimethyl sulphoxide-DMSO and hybridized it to the ÃŽ ²-globin gene and regions downstream to the gene. They observed hybridization to fragments within the ÃŽ ²-globin gene and upto 500 bp downstream to the polyadenylation site. Thus confirming that transcription terminated about 500 bp beyond the polyadenylation site in both cellular and viral transcripts. Hofer and Darnell isolated nuclei from DMSO-stimulated Friend  erythroleukemia cells and incubated them with [32P]UTP to label  run-on RNA—mostly globin pre-mRNA. Then they hybridized this  labeled RNA to DNA fragments A–F, whose locations and sizes are  given in the diagram at top. The molarities of RNA hybridization to  each fragment are given beneath each, with their standard deviations  (s.d.). In the physical map at top, the exons are in red and the introns  are in yellow. Polyadenylation signals: The polyadenylation signals depends on the kind of cell that is being transcribed. The signaling process of plants and animals also differ. At the DNA level in mammalian cells the 20 bp- ‘AATAAA’ sequence was discovered as the polyadenylation sequence by various molecular biologist in 1981. And at the RNA level, in mammalian and plants cells the ‘AAUAAA’ sequence about 20-nt upstream of their poly (A) is considered as the polyadenylation sequence. Another common variant ‘AUUAAA’ is also 80% efficient as ‘AAUAAA’. The other variants are less efficient and less common. Molly Fitzgerald and Thomas Shenk studied the importance of the RNA polyadenylation site. They created a recombinant SV40 virus with duplicate polyadenylation sequence 240 bp apart and carried out an S1 assay. They then carried out an S1 assay of the 3à ¡Ã‚ ¿Ã‚ ½-end which showed two signals 240 bp apart confirming the activity of both the sites. They then deleted one of the two polyadenylation sites one at a time and carried out the S1 assay again. The inserted polyadenylation site beyond the pre-mRNA couldn’t function if the site within the pre-mRNA was absent. Several other scientist studied this phenomenon and discovered another sequence present immediately downstream to the polyadenylation recognition site that affects polyadenylation. But the difficulty in further discovery of details regarding the same was difficult as this wasn’t a conserved sequence among invertebrates. This region was usually found to be a GU- or U- rich region 20 bp downstream to the polyadenylation recognition site. Anna Gil and Nicholas Proudfoot studied this hypothesis in detail and observed the following results: Added an extra copy of the whole polyadenylation signal upstream and carried out an S1 assay. This cloned DNA showed 90% efficiency. Deleted the 35-bp fragment containing the GU- and U- rich region. Polyadenylation process was hampered which explains its importance. Reconstructed clones containing either a GU- rich or a U- rich region. These clones showed however only 30% efficiency. Clones GU- and U- rich regions by an excess of 5-bp sequence between them. These clones showed only 30% efficiency confiming the importance of the spacing between them. Based on all these manipulations they concluded that for an efficient polyadenylation signal; (a)A polyadenylation recognition motif ‘AAUAAA’ followed by (b)A 23-25-bp GU-rich motif downstream immediately followed by (c) A U- rich motif. POLY (A) POLYMERASE: The poly (A) polymerase (PAP) was discovered by James Manley in 1991. He cloned their genome and discovered two different cDNA’s that had variable 3à ¡Ã‚ ¿Ã‚ ½ends due to two alternative splicing methods giving rise to two different PAP’s (PAP-à Ã¢â‚¬  , PAP-à Ã‚  [the most important], four additional PAP). They differ in the amino acids sequences present at their carboxy termini but the PAB-à Ã‚  consists of consensus sequences that overlap with the known functional sequences of proteins. The genome consists of :1. RNA-binding domain (RBD), 2. Polymerase module (PM), 3. Two nuclear localization signals (NLS-1 and NLS-2), 4. Serine/Threonine-rich regions S/T. Polyadenylation at the amino terminal. The mRNA is polyadenylated before leaving the cytoplasm as well as after entering the cytoplasm. However these two adenylations could be distinguished by Sheiness and Darnell due to their slight difference in size. They confirmed the same by carrying out various assays against the isolated mRNA that was grown in labeled RNA for 48 hours. The nuclear RNA, cytoplasmic RNA, and 5sRNA marker showed peaks as seen in the figure alongside. The major peaks thus obtained are 210 ±20nt and 190 ±20nt for the nuclear and cytoplasmic poly (A) tail respectively. About 50nt RNA’s are present in this broad peak. Maurice Sussman, in 1970 gave the ‘ticketing’ hypothesis which encompasses the theory of each RNA having a ticket to gain entry to the ribosome and further ticket punching everytime it got translated. Thus after a particular limit, it can’t longer undergo protein synthesis which another reason for the shortening of the poly (A) tail. Thus the 3à ¡Ã‚ ¿Ã‚ ½-end shortening of the poly(A) tail clearly depends on the some other factor other than translation or the ticket like some post-transcriptional modification. It has been observed that the poly(A) tail has not only been shortened in the cytoplasm but it also turns over. This inverted poly(A) tail is susceptible to RNase degradation and elongation by the cytoplasmic poly(A) polymerase simultaneously. This continues till the mRNA looses all or almost all of the nuclear poly(A) tail. This happens when its almost time for the demise of the mRNA. Cytoplasmic polyadenylation This process is best studied in Xenopus oocytes. Administration of progesterone to their oocytes cause stimulation of the deadenylation of maternal mRNA’or maternal message. Polyadenylation the actual process: The process involves the recognition of that conserved polyadenylation motif, RNA cleavage and polyadenylation. Pre mRNA cleavage: The proteins responsible for this cleavage are: Shrenk and his colleagues carried out various experiments confirming the importance of these cleavage factors. Cleavage polyadenylation specificity factor (CPSF)- Its one of the most important factors. Its subunit CPSF-73is related to ELAC that cleaves pre-tRNA’s to generate their 3à ¡Ã‚ ¿Ã‚ ½-end. They are known as ÃŽ ²-lactamase superfamily of Zn (as they contain 2 Zn ions at their active site necessary for RNase activity) dependent hydrolases. Cleavage stimulating factor (CSF) – Its one of the most important ones. It bindings to the GU- rich region, together and stably. Cleavage factors (CF à Ã¢â‚¬   and CF à Ã‚ )- The poly (A) polymerase- This immediate coupling is so strong that no cleaved unpolyadenylated RNA’s can be found. The RNA polymerase à Ã‚ (containing the carboxy terminal domain-CTD and its phosphorylation status). Yukata Hirose and James Manley expressed CTD as a fusion protein with glutathionine-s transferase. They then purified the protein by glutathionine affinity chromatography and the phosphorylated and non-phosphorylated forms were exposed to the cleavage assay with adenovirus L3 pre-mRNA. The results obtained confirmed that (a) the activity of CTD is independent of transcription and (b) After incubating the phosphorylated and non-phosphorylated forms of the enzyme along with all the other cleavage factors showed that the phosphorylated forms five times batter cleavage. This can be explained as the phosphorylated form of CTD is present in the polymerase à Ã‚  that carries out transcription. Polyadenylation initiation: Once the pre-mRNA is cleaved using the factors described above its polyadenylation process takes place in two phases. The first initiations phase consists of the slow addition of the first 10 A’s. This phase depends on the ‘AAUAAA’ signal. The second phase is independent of the initial ‘AAUAAA’ signal but it depends on the existing 10 A’s added to the pre-mRNA. This phase involves rapid addition of about 200 or more A’s along the length, thus called elongation. The initiation signal that carries out polyadenylation is none other than the cleavage signal which attracts the cleavage enzyme that specifically recognizes the AAUAAA motif and cuts the RNA 20 nucleotide downstream. This thaught was discarded because as the cleavage enzyme prior to polyadenylation has already cut the downstream GU-rich and U-rich sequence. Thus it’s this 8 nucleotide GU/U-rich sequence post the AAUAAA motif that brings about this adenylation. Marvin Wickens and his colleagues used two parameters (a) a poly (A) polymerase and (b) a specificity factor CPSF that binds to the pre mRNA. Both these factors work well when substrates are in high concentration but the assay carried out was using low substrate concentrations. The figure alongside explains their experiments, Lane 1- shows no polyadenylation by poly (A) polymerase by itself in low concentrations of substrates, Lane 2- shows no polyadenylation as the CPSF alone can’t detect the AAUAAA motif, Lane 3- shows polyadenylation with both factors together and Lane 4- shows that both factors can’t polyadenylate a substrate with an aberrant signal like AAUAAA. But however this dependency is temporary i.e. after the addition of the first 10 nucleotides it enters the elongation phase that’s independent of these two factors. ELONGATION OF POLY (A) TAIL: While studying the fact that the initiation is independent of the CPSF factor, another interesting fact came to be known that a purified poly (A) polymerase could carry out elongation very poorly on its own. Whale further explored this by designing experiments which consisted of purification of the poly (A) polymerase and its polyadenylation capability comparison in various conditions. Purification of the poly (A) polymerase using PAGE gave two fractions – a major 49-kD polypeptide (PAB-à Ã¢â‚¬  ) as well as a minor 70kD polypeptide (PAB-à Ã‚ ). This latter band however was found to have a variable nature and was even absent in some preparations. Whale’s experiments further showed high activity of this 49-kD polypeptide coinciding with high activity of the poly (A) polymerase using a nitrocellulose filter binding assay. He also tested this fraction’s capability of polyadenylation in the presence of the CPSF and poly (A) polymerase and found the same results. He therefore named this fraction as poly (A) binding proteinà Ã‚  (PAB- à Ã‚ ). Thus he confirmed that PAB-à Ã‚  acts like CPSF but binds to poly (A) polymerase instead of the AAUAAA motif on the RNA. Its activity is high only in the elongation phase but is found absent in the initiation phase. He carried out another experiment to find the interdependence of these two factors with their interdependence on the polyadenylation process using the poly (A) polymerase. When either CPSF or PAB-à Ã‚  was added to a solution that contained mRNA and poly (A) polymerase, the polyadenylation process was found to be active. But it showed higher polyadenylation capabilities in presence of both the factors. Thus this whole process can be summarized by the proposed figure below:-

What is an infectuos disease :: essays research papers

What is an Infectious Disease? An Infectious Disease is a disease caused by germs, such as bacteria, viruses, fungi or parasites. These diseases are all "caught", hence they are often termed communicable diseases. Examples of specific infections include Strep throat, mononucleosis, cold sores, athlete's foot, appendicitis, boils, vaginal yeast infections, African Sleeping sickness and tuberculosis. HEPATITIS B VACCINATION Safe and effective vaccines are now available for protection against hepatitis B, a serious liver infection that can result in cirrhosis and liver cancer. Hepatitis B vaccine prevents hepatitis B disease and its serious consequences. Use of hepatitis B vaccine and other vaccines is strongly endorsed by the medical, scientific and public health communities as a safe and effective way to prevent disease and death. There is no confirmed evidence that indicates that hepatitis B vaccine can cause chronic illnesses. Whenever large number of vaccines are given, some adverse events will occur coincidentally after vaccination and be falsely attributed to the vaccine. To assure a high standard of safety with vaccines, several federal agencies continually assess and research possible or potential health effects that could be associated with vaccines. The Centers for Disease Control and the American Academy of Pediatrics recommend that all newborns, infants and children, especially sexually active teenagers be vaccinated against hepatitis B. Vaccination is also recommended for individuals at high risk of being infected with the hepatitis B virus (HBV). These include:  · Health care workers, including doctors, dentists, nurses, blood and lab technicians;  · Emergency workers - including paramedics, fire fighters and police;  · Hemodialysis patients;  · Military personnel;  · Morticians and embalmers;  · Patients and staff of institutions for the mentally handicapped, inmates of long-term correctional institutions;  · Ethnic groups with a high rate of hepatitis B including Chinese, Koreans, Indochinese, Filipinos, Alaskan Eskimos, Haitians, and American Indians;  · People with multiple sexual partners;  · Intravenous drug users;  · Recipients of certain blood products;  · Household contacts and sex partners of hepatitis B carriers;  · International travelers Those who are already infected will not benefit from vaccination. However, infants born of mothers who are carriers of the hepatitis B virus can be protected. A simple blood test can determine whether someone is a hepatitis B carrier. Immunization requires three doses of vaccine according to the following schedule:  · 1st dose: For infants born to infected mothers - within 12 hours. For infants born to mothers who test negative - within one to two months following delivery.  · 2nd dose: 1 month later  · 3rd dose: 6 months after the first dose.

Accounting Statement of Purpose

Hello! I am going to apply to Msc Accounting and Finance Management programme. I would be grateful if you could give me feedback. :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::: I studied a Bachelor's degree in Accounting. During the undergraduate degree I took a variety of subjects in taxes, finance, auditing, economics, accounting and business management. Taking a variety of subjects in university allowed me to see where my interests and strengths lie.The subjects that grabbed my attention during the final year in the university were taxation, business management and finance. It was through doing these subjects that I discovered I would like to pursue my career in either of these fields. As part of my desire to have a broad knowledge in business management, I wrote the final-year dissertation focused on this field. Which was titled â€Å"How far proper management lead your business to success†. In July 2007, I was hired by one of the big four accountancy firms, where I develop an employment as tax consultant.Through this job, I have understood the important role played by the accountancy in business. Definitely book-keeping, preparing financial statements, establishing and maintaining accurate financial records provide a general overview of how business is doing. In my experience I have realized that accountants specialized in taxation besides technical-legal knowledge, they must have wide knowledge of accounting and its procedures as well as theory to properly evaluate financial information.With this knowledge the consultants must be able to ensure if records are accurate according with government regulations, identify companies' opportunities and provide advice on improving efficiency. The reasons mentioned above besides my long-term goal to pursue a career as a controller encourage me to seek for a professional accounting and finance management program, which allow me to obtain the abilit y to effectively analyze accounting records, interpret financial statements as well as acquired a wide overview regarding management functions within an organization.Selecting a graduate school is not an easy task; there are certain aspects to look at while considering a school. After comparing some accounting and finance programs provide by Dublin universities. I found the MSC at Griffith College like the one that meet my academic and professional goals. Other reasons to choose this colleges are: its prestige, it is recognized as one of the top private universities in Dublin, program' structure which fully meets my academic and professional objectives, the subjects that caught my attention are: international financial management.I am certain that the MSC in accounting and finance management provided by Griffith College will provide a lot of advantages besides helping me to achieve my academic and professional objectives, such as: improve foreign language skills, opportunity to work with people from diverse backgrounds, exposure to new learning environments, cultures, obtain an international perspective and by this way understand other points of view, enhance future job prospects. I am certain that the wide knowledge that the Msc in accounting and finance management provides, will give me with the necessary tools to succeed in my career.

Air Water Soil Noise Pollution Essay

Pollution is the introduction of contaminants into an environment that causes instability, disorder, harm or discomfort to the ecosystem i. e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat, or light. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution became a popular issue after World War II, due to radioactive fallout from atomic warfare and testing. Then a non-nuclear event, The Great Smog of 1952 in London, killed at least 4000 people. This prompted some of the first major modern environmental legislation, The Clean Air Act of 1956. Air pollution Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment into the atmosphere. The atmosphere is a complex dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth’s ecosystems. Pollutants An air pollutant is known as a substance in the air that can cause harm to humans and the environment. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made. Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone — one of the many secondary pollutants that make up photochemical smog. Major primary pollutants produced by human activity include: Sulfur oxides (SOx) – especially sulfur dioxide, a chemical compound with the formula SO2. SO2 is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide. Further oxidation of SO2, usually in the presence of a catalyst such as NO2, forms H2SO4, and thus acid rain. [2] This is one of the causes for concern over the environmental impact of the use of these fuels as power sources. Nitrogen oxides (NOx) – especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities. Nitrogen dioxide is the chemical compound with the formula NO2. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odor. NO2 is one of the most prominent air pollutants. Carbon monoxide – is a colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide. Carbon dioxide (CO2) – a greenhouse gas emitted from combustion but is also a gas vital to living organisms. It is a natural gas in the atmosphere. Odors — such as from garbage, sewage, and industrial processes Radioactive pollutants – produced by nuclear explosions, war explosives, and natural processes such as the radioactive decay of radon. Secondary pollutants include:  Particulate matter formed from gaseous primary pollutants and compounds in photochemical smog. Smog is a kind of air pollution; the word â€Å"smog† is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide. Modern smog does not usually come from coal but from vehicular and industrial emissions that are acted on in the atmosphere by sunlight to form secondary pollutants that also combine with the primary emissions to form photochemical smog. Ground level ozone (O3) formed from NOx and VOCs. Ozone (O3) is a key constituent of the troposphere (it is also an important constituent of certain regions of the stratosphere commonly known as the Ozone layer). Photochemical and chemical reactions involving it drive many of the chemical processes that occur in the atmosphere by day and by night. At abnormally high concentrations brought about by human activities (largely the combustion of fossil fuel), it is a pollutant, and a constituent of smog. Peroxyacetyl nitrate (PAN) – similarly formed from NOx and VOCs. Minor air pollutants include: A large number of minor hazardous air pollutants. Some of these are regulated in USA under the Clean Air Act and in Europe under the Air Framework Directive. A variety of persistent organic pollutants, which can attach to particulate matter. Persistent organic pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulate in human and animal tissue, biomagnify in food chains, and to have potential significant impacts on human health and the environment. Health effects of Air Pollution: The World Health Organization states that 2. 4 million people die each year from causes directly attributable to air pollution, with 1. 5 million of these deaths attributable to indoor air pollution. Worldwide more deaths per year are linked to air pollution than to automobile accidents. Direct causes of air pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies. The worst short term civilian pollution crisis in India was the 1984 Bhopal Disaster. Leaked industrial vapors from the Union Carbide factory, belonging to Union Carbide, Inc. , U. S. A. , killed more than 2,000 people outright and injured anywhere from 150,000 to 600,000 others, some 6,000 of whom would later die from their injuries. The United Kingdom suffered its worst air pollution event when the December 4 Great Smog of 1952 formed over London. In six days more than 4,000 died, and 8,000 more died within the following months Water pollution Water pollution is the contamination of water bodies (e. g. lakes, rivers, oceans, groundwater). Water pollution affects plants and organisms living in these bodies of water; and, in almost all cases the effect is damaging not only to individual species and populations, but also to the natural biological communities. Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds. Causes of water pollution The specific contaminants leading to pollution in water include a wide spectrum of chemicals, pathogens, and physical or sensory changes such as elevated temperature and discoloration. While many of the chemicals and substances that are regulated may be naturally occurring (calcium, sodium, iron, manganese, etc. ) the concentration is often the key in determining what is a natural component of water, and what is a contaminant. Oxygen-depleting substances may be natural materials, such as plant matter (e. g. leaves and grass) as well as man-made chemicals. Other natural and anthropogenic substances may cause turbidity (cloudiness) which blocks light and disrupts plant growth, and clogs the gills of some fish species. Many of the chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Effects of Water Pollution Water pollution is a major problem in the global context An estimated 700 million Indians have no access to a proper toilet, and 1,000 Indian children die of diarrheal sickness every day. Some 90% of China’s cities suffer from some degree of water pollution, and nearly 500 million people lack access to safe drinking water. Chemical and other contaminants Organic water pollutants include: Detergents Disinfection by-products found in chemically disinfected drinking water, such as chloroform Food processing waste, which can include oxygen-demanding substances, fats and grease Insecticides and herbicides, a huge range of organohalides and other chemical compounds Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and lubricants (motor oil), and fuel combustion byproducts, from stormwater runoff[15] Tree and bush debris from logging operations Volatile organic compounds (VOCs), such as industrial solvents, from improper storage. Chlorinated solvents, which are dense non-aqueous phase liquids (DNAPLs), may fall to the bottom of reservoirs, since they don’t mix well with water and are denser. Various chemical compounds found in personal hygiene and cosmetic products Inorganic water pollutants include: Acidity caused by industrial discharges (especially sulfur dioxide from power plants) Ammonia from food processing waste Chemical waste as industrial by-products Fertilizers containing nutrients–nitrates and phosphates–which are found in stormwater runoff from agriculture, as well as commercial and residential use[15] Heavy metals from motor vehicles (via urban stormwater runoff)[15][16] and acid mine drainage Silt (sediment) in runoff from construction sites, logging, slash and burn practices or land clearing sites Land pollution Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Land pollution is the degradation of Earth’s land surfaces often caused by human activities and their misuse of land resources. It occurs when waste is not disposed properly. Health hazard disposal of urban and industrial wastes, exploitation of minerals, and improper use of soil by inadequate agricultural practices are a few factors. Urbanization and industrialization are major causes of land pollution. Increased mechanization The major increase in the concentration of population in cities, along with the internal combustion engine, led to the increased number of roads and all the infra structure that goes with them. Roads cause visual, noise, light, air and water pollution, in addition to land pollution. The visual and noise areas are obvious, however light pollution is becoming more widely recognized as a problem. From outer space, large cities can be picked out at night by the glow of their lighting, so city dwellers seldom experience total darkness. As the demand for food has grown very high, there is an increase in field size and mechanization. The increase in field size makes t economically viable for the farmer but results in loss of person and shelter for wildlife, as hedgerows and copses disappear. When crops are harvested, the naked soil is left open to wind after the heavy machinery has compacted it. Another consequence of more intensive agriculture is the move to monoculture. This is unnatural, it depletes the soil of nutrients, allows diseases and pests to spread and, in short, brings into play the use of chemical substances foreign to the environment. A pesticide is a substance or m ixture of substances used to kill a pest. A pesticide may be a chemical substance, biological agent (such as a virus or bacteria), antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes (roundworms) and microbes that compete with humans for food, destroy property, spread or are a vector for disease or cause a nuisance. Although there are benefits to the use of pesticides, there are also drawbacks, such as potential toxicity to humans and other organisms. Pesticides are used to control organisms which are considered harmful. For example, they are used to kill mosquitoes that can transmit many potentially deadly diseases like west Nile virus, yellow fever, and malaria disease. They can also kill bees, wasps or ants that can cause allergic reactions. Insecticides can protect animals from illnesses that can be caused by parasites such as fleas. Pesticides can prevent sickness in humans that could be caused by moldy food or diseased produce. Mining Modern mining projects leave behind disrupted communities, damages landscapes, and polluted water. Mining also affects ground and surface waters, the aquatic life, vegetation, soils, animals, and the human health. Acid mine drainage can cause damage to streams which in return can kill aquatic life. The vast variety of toxic chemicals released by mining activities can harm animals and aquatic life as well as their habitat. The average mine disturbs over a thousand acres of land. Construction See the bodies of water. doing this, natural water filters are damaged. Natural water filters help break down many pollutants before they reach other water bodies. Some that may run off with water and sediments from construction sites are oils, debris, and paint. This can cause damage to soil, aquatic life, and promote hazardous chemicals to get into drinking water. Effects A large percentage of material that is dumped into waters not only destroys habitats for animals but for humans as well. Below is a list of some impacts of land pollution. There are some habitats, where aquatic animals feed and live, so there is a risk of destruction of habitat of aquatic animals. Reduced oxygen levels from decomposition of organic material dumped from drains. Reduced light penetration in the water column, from sediments and excessive algal growth, leading to oxygen depleted water. *Massively changed flow regimes, large fast flows can scour existing habitat and wash species downstream. Increased human health risks, from syringes, broken glass and cans washing onto creek banks and beaches. Reduced aesthetic appeal of areas from litter strewn on banks and beaches, thus reducing recreation and tourist appeal. Acid rain damages trees and other plants.