Sunday, August 15, 2010
Thursday, August 12, 2010
Joe Biden
Joseph Robinette "Joe" Biden, Jr is the 47th and current Vice President of the United States, serving under President Barack Obama.
Wednesday, August 11, 2010
Polio http://kidshealth.org/parent/infections/bacterial_viral/polio.html#
Polio (also called poliomyelitis) is a contagious, historically devastating disease that was virtually eliminated from the Western hemisphere in the second half of the 20th century. Although polio has plagued humans since ancient times, its most extensive outbreak occurred in the first half of the 1900s before the vaccination, created by Jonas Salk, became widely available in 1955.
At the height of the polio epidemic in 1952, nearly 60,000 cases with more than 3,000 deaths were reported in the United States alone. However, with widespread vaccination, wild-type polio, or polio occurring through natural infection, was eliminated from the United States by 1979 and the Western hemisphere by 1991.
Signs and Symptoms
Polio is a viral illness that, in about 95% of cases, actually produces no symptoms at all (called asymptomatic polio). In the 4% to 8% of cases in which there are symptoms (called symptomatic polio), the illness appears in three forms:
- a mild form called abortive polio (most people with this form of polio may not even suspect they have it because their sickness is limited to mild flu-like symptoms such as mild upper respiratory infection, diarrhea, fever, sore throat, and a general feeling of being ill)
- a more serious form associated with aseptic meningitis called nonparalytic polio (1% to 5% show neurological symptoms such as sensitivity to light and neck stiffness)
- a severe, debilitating form called paralytic polio (this occurs in 0.1% to 2% of cases)
People who have abortive polio or nonparalytic polio usually make a full recovery. However, paralytic polio, as its name implies, causes muscle paralysis - and can even result in death. In paralytic polio, the virus leaves the intestinal tract and enters the bloodstream, attacking the nerves (in abortive or asymptomatic polio, the virus usually doesn't get past the intestinal tract). The virus may affect the nerves governing the muscles in the limbs and the muscles necessary for breathing, causing respiratory difficulty and paralysis of the arms and legs.
Contagiousness
Polio is transmitted primarily through the ingestion of material contaminated with the virus found in stool (poop). Not washing hands after using the bathroom and drinking contaminated water were common culprits in the transmission of the disease.
Prevention
In the United States, it's currently recommended that children have four doses of inactivated polio vaccination (IPV) between the ages of 2 months and 6 years.
By 1964, the oral polio vaccine (OPV), developed by Albert Sabin, had become the recommended vaccine. OPV allowed large populations to be immunized because it was easy to administer, and it provided "contact" immunization, which means that an unimmunized person who came in contact with a recently immunized child might become immune, too. The problem with OPV was that, in very rare cases, paralytic polio could develop either in immunized children or in those who came in contact with them.
Since 1979 (when wild polio was eliminated in the United States), the approximately 10 cases per year of polio seen in this country were traced to OPV.
IPV is a vaccine that stimulates the immune system of the body (through production of antibodies) to fight the virus if it comes in contact with it. IPV cannot cause polio.
In an effort to eradicate all polio, including those cases associated with the vaccine, the Centers for Disease Control and Prevention (CDC) decided to make IPV the only vaccine given in the United States. Currently, the CDC and American Academy of Pediatrics (AAP) recommend three spaced doses of IPV given before the age of 18 months, and an IPV booster given between the ages of 4 to 6, when children are entering school.
If you're planning to travel outside the United States, particularly to Africa and Asia (where polio still exists), be sure that you and your child have received a complete set of polio vaccinations.
Duration
Although the acute illness usually lasts less than 2 weeks, damage to the nerves could last a lifetime. In the past, some patients with polio never regained full use of their limbs, which would appear withered. Those who did fully recover might go on to develop post-polio syndrome (PPS) as many as 30 to 40 years after contracting polio. In PPS, the damage done to the nerves during the disease causes an acceleration of the normal, gradual weakness due to aging.
Treatment
In the height of the polio epidemic, the standard treatment involved placing a patient with paralysis of the breathing muscles in an "iron lung" - a large machine that actually pushed and pulled the chest muscles to make them work. The damaged limbs were often kept immobilized because of the confinement of the iron lung. In countries where polio is still a concern, ventilators and some iron lungs are still used.
Historically, home treatment for paralytic polio and abortive polio with neurological symptoms wasn't sufficient. However, asymptomatic and mild cases of abortive polio with no neurological symptoms were usually treated like the flu, with plenty of fluids and bed rest.
The Future of Polio
The World Health Organization (WHO) is working toward eradicating polio throughout the world. Significant strides have already been made. In 1988, 355,000 cases of polio in 125 countries were reported. By the end of 2004, there were just 1,255 cases.
Six countries (Afghanistan, Egypt, India, Niger, Nigeria, and Pakistan) still have polio circulating, and the virus could be introduced to other countries. If the polio virus is imported into a country where not enough people have been immunized, there's the risk that it could spread from person to person. That's what has happened in some countries in Africa and Asia. So until it has been eliminated worldwide, it's important to continue vaccinating kids against polio.
Reviewed by: Steven Dowshen, MD
Date reviewed: December 2007
Originally reviewed by: Joel Klein, MD
Ozone layer
The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 97–99% of the sun's high frequency ultraviolet light, which is potentially damaging to life on earth.[1] Over 90% of the ozone in Earth's atmosphere is present here.[1] It is mainly located in the lower portion of the stratosphere from approximately 13 km to 20 km above Earth, though the thickness varies seasonally and geographically.[2] The ozone layer was discovered in 1913 by the French physicists Charles Fabry and Henri Buisson. Its properties were explored in detail by the British meteorologist G. M. B. Dobson, who developed a simple spectrophotometer (the Dobsonmeter) that could be used to measure stratospheric ozone from the ground. Between 1928 and 1958 Dobson established a worldwide network of ozone monitoring stations which continues to operate today. The "Dobson unit", a convenient measure of the columnar density of ozone overhead, is named in his honour.
This stratospheric ozone, which protects us from the sun, is good. There is also ozone produced near the ground, from sunlight interacting with atmospheric pollution in cities, that is bad. It causes breathing problems for some people, and usually occurs in the summertime when the pollution over a city builds up during stagnant air conditions associated with high pressure areas.
What is the ozone layer?
The ozone layer is a deep layer in the stratosphere, encircling the Earth, that has large amounts of ozone in it. The layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun. Interestingly, it is also this ultraviolet radiation that forms the ozone in the first place. Ozone is a special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms. It usually forms when some type of radiation or electrical discharge separates the two atoms in an oxygen molecule (O2), which can then individually recombine with other oxygen molecules to form ozone (O3). The ozone layer became more widely appreciated when it was realized that certain chemicals mankind manufactures, called chloroflurocarbons, find their way up into the stratosphere where, through a complex series of chemical reactions, they destroy some of the ozone. As a result of this discovery, an international treaty was signed, the the manufacture of these chemicals was stopped. The ozone layer has since begun to recover as a result of these efforts.This stratospheric ozone, which protects us from the sun, is good. There is also ozone produced near the ground, from sunlight interacting with atmospheric pollution in cities, that is bad. It causes breathing problems for some people, and usually occurs in the summertime when the pollution over a city builds up during stagnant air conditions associated with high pressure areas.
The Ozone Layer
Ozone is a gas that occurs naturally in our atmosphere. Most of it is concentrated in the ozone layer, a region located in the stratosphere several miles above the surface of the Earth. Although ozone represents only a small fraction of the gas present in the atmosphere, it plays a vital role by shielding humans and other life from harmful ultraviolet light from the Sun. Human activities in the last several decades have produced chemicals, such as chlorofluorocarbons (CFCs), which have been released into the atmosphere and have contributed to the depletion of this important protective layer. When scientists realized the destructive effect these chemicals could have on the ozone layer, international agreements were put in place to limit such emissions. As a result, it is expected that the ozone layer will recover in the coming decades.
Ozone is also a greenhouse gas in the upper atmosphere and, therefore, plays a role in Earth's climate. The increases in primary greenhouse gases, such as carbon dioxide, may affect how the ozone layer recovers in coming years. Understanding precisely how ozone abundances will change in a future with diminished chlorofluorocarbon emissions and increased emissions of greenhouse gases remains an important challenge for atmospheric scientists in NOAA and other research centers.
Ozone Research
NOAA Research has, for many years, played a vital role in studying the ozone layer. For instance, at the Chemical Sciences Division of ESRL, researchers are conducting laboratory and field experiments and designing computer models to study this issue. One of the primary missions of ESRL's Global Monitoring Division is to observe and understand the ozone layer through accurate, long-term measurements of ozone, chlorofluorocarbons, greenhouse gases, and solar radiation.
Taking Observations
NOAA researchers build and deploy instruments all over the world to measure ozone, as well as the trace gases and aerosol particles that affect its abundance. They also participate in many field experiments to study and document the processes that control atmospheric ozone. Research scientists take ozone measurements using instruments located on the ground and onboard aircraft, balloons, and satellites. The data from these instruments provide precise measurements that can be used to detect small regional ozone changes over long periods of time, provide global maps of ozone amounts and examine local ozone distributions.
Ozone Depletion
Antarctica
Ozone depletion occurs in many places in the Earth's ozone layer, most severely in the polar regions. NOAA scientists have traveled to Antarctica to study the ozone hole that has been occurring there since the late 1970s. In 1986, soon after the reported discovery of the ozone hole, Aeronomy Lab (now ESRL) scientist Dr. Susan Solomon led a team of 16 scientists, the National Ozone Expedition (NOZE I), to Antarctica. The scientists took measurements of various trace gases and physical properties of the atmosphere. The data, along with additional findings from the NOZE II mission the following year, showed conclusively that human-produced trace gases that contain chlorine and bromine were causing the ozone hole. The Global Monitoring Division of ESRL has monitored the yearly Antarctic ozone hole since 1986 by launching balloon-borne ozonesondes, from the South Pole station and measuring total column ozone from a ground based Dobson spectrophotometer since 1963.
This unique record from the South Pole station clearly shows the annual development of the springtime Antarctic ozone hole over the past two decades. Ozone depletion at the South Pole can also be viewed from another perspective through the images created from data collected by the NASA TOMS satellite, and the NOAA SBUV-2 instruments aboard NOAA satellites. These various ozone measurements provide an important record of the status of the ozone hole. Continued surveillance is necessary in order to verify the expected recovery of the ozone layer.
Arctic Ozone
Significant depletion also occurs in the Arctic ozone layer during the late winter and spring period (January - April). However, the maximum depletion is generally less severe than that observed in the Antarctic, with no large and recurrent ozone hole taking place in the Arctic.
Since the 1980's, scientists at ESRL have been participants in field, theoretical, and laboratory research to demonstrate some of the key processes that contribute to the observed difference between the depletion of ozone in the Arctic and Antarctic. For example, the POLARIS mission in 1997, was designed to study ozone photochemistry in the Arctic during the summertime at middle and high latitudes. And later, the SAGE III Ozone Loss and Validation Experiment (SOLVE) campaign was designed to examine the processes controlling ozone levels at mid- to high latitudes in the Arctic during the winter. The mission also acquired correlative data needed to validate the Stratospheric Aerosol and Gas Experiment (SAGE) III satellite measurements that are used to quantify high-latitude ozone loss. Both these experiments took measurements using the NASA DC-8 and ER-2 aircraft, as well as balloon platforms and ground-based instruments
Atmospheric Models
Another NOAA lab involved in studying stratospheric ozone depletion is the Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, N.J. GFDL seeks to understand and predict the Earth's climate and weather, including the impact of human activities. Specifically, GFDL conducts leading-edge research (i.e., atmospheric chemistry modeling) on many topics of great practical value, including stratospheric ozone depletion. For example, the GFDL group developed a 3-D atmospheric model tailored to study the interaction of chemistry, dynamics, and radiation in the stratosphere. Their extensive calculations were necessary for evaluating the simpler models used in the policy assessment studies, as well as for understanding the climatic impact of the Antarctic ozone hole.
Ozone-Depleting Substances
Certain industrial processes and consumer products result in the atmospheric emission of ozone-depleting gases. These gases contain chlorine and bromine atoms, which are known to be harmful to the ozone layer. Important examples are the CFCs and hydrochlorofluorocarbons (HCFCs), human-produced gases once used in almost all refrigeration and air conditioning systems. These gases eventually reach the stratosphere, where they are broken apart to release ozone-depleting chlorine atoms. Other examples are the halons,which are used in fire extinguishers and which contain ozone-depleting bromine atoms.
Methyl bromide, is another important area of research for NOAA scientists. Primarily used as an agricultural fumigant, it is also a significant source of bromine to the atmosphere. Although some ozone-depleting gases also are emitted from natural sources, emissions from human activities exceed those from natural sources.
NOAA researchers regularly measure ozone depleting gases in the lower and upper atmosphere and attempt to account for observed changes. As a result of international regulations, ozone-depleting gases are being replaced in human activities with "ozone-friendly" gases that have much reduced potential to deplete ozone. NOAA researchers are also measuring these "substitute" gases as they accumulate in the atmosphere. Observing changes in both old and new gases emitted into the atmosphere allows researchers to improve our understanding of the fate of these gases after release and thereby improve our ability to predict future ozone changes.
Winter Ozone Summaries
The full range of ground-based and satellite-based observations from several NOAA offices are collected together and used to describe the past Arctic or Antarctic winter in the Climate Prediction Center's Winter Ozone Summaries. The contributors include the National Weather Service's Climate Prediction Center (CPC), NOAA Research and the National Environmental Satellite, Data, Information Services (NESDIS). By monitoring and researching stratospheric ozone, as well as the chemical compounds and atmospheric conditions that affect its concentration, NOAA has contributed vital information toward protecting the Earth's stratospheric ozone layer. Perhaps most notable is NOAA's instrumental role in providing ozone data and analysis for the United Nations Environmental Programme and World Meteorological Organization.
Communicating Information on Ozone depletion
The world's population is a stakeholder in decisions that limit the emissions of ozone-depleting gases. In 1987, the international community put in place a treaty known as the Montreal Protocol on Substances that Deplete the Ozone Layer 
http://www.oar.noaa.gov/climate/t_ozonelayer.html
Julia Fischer
Julia Fischer
Julia Fischer (born June 15, 1983(1983-06-15)) is a German classical violinist. By training she is also a pianist, but she rarely performs in public on that instrument.[1]
Subscribe to:
Posts (Atom)