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Controlling Vehicular Air Pollution: A Case Study of Delhi

 Controlling Vehicular Air Pollution: A Case Study of Delhi   With its very large population of vehicular traffic, Delhi leads the country in its levels of air-pollution – it has more cars than the states of Gujarat and West Bengal put together.  In the 1990s, Delhi ranked fourth among the 41 most polluted cities of the world.  Air pollution problems in Delhi became so serious that a public interest litigation (PIL) was filed in the Supreme Court of India.  After being censured very strongly by the Supreme Court, under its directives, the government was asked to take, within a specified time period, appropriate measures, including switching over the entire fleet of public transport, i.e., buses, from diesel to compressed natural gas (CNG).  All the buses of Delhi were converted to run on CNG by the end of 2002.  You may ask the question as to why CNG is better than diesel. The answer is that CNG burns most efficiently, unlike petrol or diesel, in the a...
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HUMAN EXCRETORY SYSTEM

  😎 HUMAN EXCRETORY SYSTEM  😎  In humans, the excretory system consists of a pair of kidneys, one pair of ureters, a urinary bladder and a urethra.  Kidneys are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebra close to the dorsal inner wall of the abdominal cavity.  Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120- 170 g. Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter.  Inner to the hilum is a broad funnel shaped space called the renal pelvis with projections called calyces.  The outer layer of kidney is a tough capsule.  Inside the kidney, there are two zones, an outer cortex and an inner medulla.  The medulla is divided into a few conical masses (medullary pyramids) projecting into the calyces (sing.: calyx)....
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Solid Waste

 SOLID WASTES  Solid wastes refer to everything that goes out in trash.  Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality.  The municipal solid wastes generally comprise paper, food wastes, plastics, glass, metals, rubber, leather, textile, etc.  Burning reduces the volume of the wastes, although it is generally not burnt to completion and open dumps often serve as the breeding ground for rats and flies.  Sanitary landfills were adopted as the substitute for open-burning dumps.  In a sanitary landfill, wastes are dumped in a depression or trench after compaction, and covered with dirt everyday.  Landfills are also not really much of a solution since the amount of garbage generation specially in the metros has increased so much that these sites are getting filled too.  Also there is danger of seepage of chemicals, etc., from these landfills polluting th...
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DISORDERS OF CIRCULATORY SYSTEM

  DISORDERS OF CIRCULATORY SYSTEM   High Blood Pressure (Hypertension):   Hypertension is the term for blood pressure that is higher than normal (120/80).  In this measurement 120 mm Hg (millimetres of mercury pressure) is the systolic, or pumping, pressure and 80 mm Hg is the diastolic, or resting, pressure.  If repeated checks of blood pressure of an individual is 140/90 (140 over 90) or Schematic plan of blood circulation in human higher, it shows hypertension.  High blood pressure leads to heart diseases and also affects vital organs like brain and kidney.  Coronary Artery Disease (CAD):   Coronary Artery Disease, often referred to as atherosclerosis, affects the vessels that supply blood to the heart muscle.  It is caused by deposits of calcium, fat, cholesterol and fibrous tissues, which makes the lumen of arteries narrower.  Angina:   It is also called ‘ angina pectori s’.  A symptom of acute chest pain appears when no e...
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AIR POLLUTION

AIR POLLUTION   We are dependent on air for our respiratory needs.  Air pollutants cause injury to all living organisms.  They reduce growth and yield of crops and cause premature death of plants.  Air pollutants also deleteriously affect the respiratory system of humans and of animals.  Harmful effects depend on the concentration of pollutants, duration of exposure and the organism.  Smokestacks of thermal power plants, smelters and other industries release particulate and gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.  These pollutants must be separated/ filtered out before releasing the harmless gases into the atmosphere.  Electrostatic precipitator There are several ways of removing particulate matter; the most widely used of which is the electrostatic precipitator, which can remove over 99 per cent particulate matter present in the exhaust from a thermal power plant.  It has electrode wires that are m...
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ELECTROCARDIOGRAPH

  Electrocardiograph (ECG)  You are probably familiar with this scene from a typical hospital television show: A patient is hooked up to a monitoring machine that shows voltage traces on a screen and makes the sound “... pip... pip... pip..... peeeeeeeeeeeeeeeeeeeeee” as the patient goes into cardiac arrest.  This type of machine (electro-cardiograph) is used to obtain an electrocardiogram (ECG). ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle.  To obtain a standard ECG, a patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity.  For a detailed evaluation of the heart’s function, multiple leads are attached to the chest region.  Here, we will talk only about a standard ECG.  Each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.  The P-...
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DOUBLE CIRCULATION

 DOUBLE CIRCULATION   The blood flows strictly by a fixed route through Blood Vessels—the arteries and veins.  Basically, each artery and vein consists of three layers: an inner lining of squamous endothelium, the tunica intima, a middle layer of smooth muscle and elastic fibres, the tunica media, and an external layer of fibrous connective tissue with collagen fibres, the tunica externa.  The tunica media is comparatively thin in the veins.  As mentioned earlier, the blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta.  The deoxygenated blood pumped into the pulmonary artery is passed on to the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium.  This pathway constitutes the pulmonary circulation. The oxygenated blood entering the aorta is carried by a network of arteries, arterioles and capillaries to the tissues from where the deoxygenated bl...
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