Sunday, May 23, 2010


Anemia (pronounced /əˈniːmiə/, also spelled anaemia and anæmia; from Ancient Greek ἀναιμία anaimia, meaning lack of blood) is a decrease in normal number of red blood cells (RBCs) or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin deficiency.
Because hemoglobin (found inside RBCs) normally carries oxygen from the lungs to the tissues, anemia leads to hypoxia (lack of oxygen) in organs. Because all human cells depend on oxygen for survival, varying degrees of anemia can have a wide range of clinical consequences.
Anemia is the most common disorder of the blood. There are several kinds of anemia, produced by a variety of underlying causes. Anemia can be classified in a variety of ways, based on the morphology of RBCs, underlying etiologic mechanisms, and discernible clinical spectra, to mention a few. The three main classes of anemia include excessive blood loss (acutely such as a hemorrhage or chronically through low-volume loss), excessive blood cell destruction (hemolysis) or deficient red blood cell production (ineffective hematopoiesis).
There are two major approaches: the "kinetic" approach which involves evaluating production, destruction and loss, and the "morphologic" approach which groups anemia by red blood cell size. The morphologic approach uses a quickly available and cheap lab test as its starting point (the MCV). On the other hand, focusing early on the question of production may allow the clinician more rapidly to expose cases where multiple causes of anemia coexist.

Signs and symptoms
Anemia goes undetected in many people, and symptoms can be minor or vague. The signs and symptoms can be related to the anemia itself, or the underlying cause.
Most commonly, people with anemia report non-specific symptoms of a feeling of weakness, or fatigue, general malaise and sometimes poor concentration. They may also report shortness of breath, dyspnea, on exertion. In very severe anemia, the body may compensate for the lack of oxygen carrying capability of the blood by increasing cardiac output. The patient may have symptoms related to this, such as palpitations, angina (if preexisting heart disease is present), intermittent claudication of the legs, and symptoms of heart failure.
On examination, the signs exhibited may include pallor (pale skin, mucosal linings and nail beds) but this is not a reliable sign. There may be signs of specific causes of anemia, e.g., koilonychia (in iron deficiency), jaundice (when anemia results from abnormal break down of red blood cells — in hemolytic anemia), bone deformities (found in thalassaemia major) or leg ulcers (seen in sickle cell disease).
In severe anemia, there may be signs of a hyperdynamic circulation: a fast heart rate (tachycardia), flow murmurs, and cardiac enlargement. There may be signs of heart failure.
Pica, the consumption of non-food based items such as dirt, paper, wax, grass, ice, and hair, may be a symptom of iron deficiency, although it occurs often in those who have normal levels of hemoglobin.
Chronic anemia may result in behavioral disturbances in children as a direct result of impaired neurological development in infants, and reduced scholastic performance in children of school age.
Restless legs syndrome is more common in those with iron deficiency anemia.
Less common symptoms may include swelling of the legs or arms, chronic heartburn, vague bruises, vomiting, increased sweating, and blood in stool.

Possible complications
Anemia diminishes the capability of affected individuals to perform physical activities, a result of one's muscles being forced to depend on anaerobic metabolism. The lack of iron associated with anemia can cause many complications, including hypoxemia, brittle or rigid fingernails, cold intolerance, and possible behavioral disturbances in children. Hypoxemia resulting from anemia can worsen the cardio-pulmonary status of patients with pre-existing chronic pulmonary disease. Cold intolerance occurs in one in five patients with iron deficiency anemia, and becomes visible through numbness and tingling.

There are many different treatments for anemia and the treatment depends on severity and the cause.
Iron deficiency from nutritional causes is rare in non-menstruating adults (men and post-menopausal women). The diagnosis of iron deficiency mandates a search for potential sources of loss such as gastrointestinal bleeding from ulcers or colon cancer. Mild to moderate iron deficiency anemia is treated by oral iron supplementation with ferrous sulfate, ferrous fumarate, or ferrous gluconate. When taking iron supplements, it is very common to experience stomach upset and/or darkening of the feces. The stomach upset can be alleviated by taking the iron with food; however, this decreases the amount of iron absorbed. Vitamin C aids in the body's ability to absorb iron, so taking oral iron supplements with orange juice is of benefit.
Vitamin supplements given orally (folic acid) or subcutaneously (vitamin B-12) will replace specific deficiencies.
In anemia of chronic disease, anemia associated with chemotherapy, or anemia associated with renal disease, some clinicians prescribe recombinant erythropoietin, epoetin alfa, to stimulate red cell production.
In severe cases of anemia, or with ongoing blood loss, a blood transfusion may be necessary.

Blood transfusions
Doctors attempt to avoid blood transfusion in general, since multiple lines of evidence point to increased adverse patient clinical outcomes with more intensive transfusion strategies. The physiological principle that reduction of oxygen delivery associated with anemia leads to adverse clinical outcomes is balanced by the finding that transfusion does not necessarily mitigate these adverse clinical outcomes.
In severe, acute bleeding, transfusions of donated blood are often lifesaving. Improvements in battlefield casualty survival is attributable, at least in part, to the recent improvements in blood banking and transfusion techniques.
Transfusion of the stable but anemic hospitalized patient has been the subject of numerous clinical trials, and transfusion is emerging as a deleterious intervention.
Four randomized controlled clinical trials have been conducted to evaluate aggressive versus conservative transfusion strategies in critically ill patients. All four of these studies failed to find a benefit with more aggressive transfusion strategies.
In addition, at least two retrospective studies have shown increases in adverse clinical outcomes with more aggressive transfusion strategies.

Hyperbaric oxygen
Treatment of exceptional blood loss (anemia) is recognized as an indication for hyperbaric oxygen (HBO) by the Undersea and Hyperbaric Medical Society. The use of HBO is indicated when oxygen delivery to tissue is not sufficient in patients who cannot be transfused for medical or religious reasons. HBO may be used for medical reasons when threat of blood product incompatibility or concern for transmissible disease are factors.
In 2002, Van Meter reviewed the publications surrounding the use of HBO in severe anemia and found that all publications report a positive result.

Thursday, May 20, 2010

Ibn Bajjah

Abū-Bakr Muhammad ibn Yahya ibn al-Sāyigh (Arabic أبو بكر محمد بن يحيى بن الصائغ), known as Ibn Bājjah (Arabic: ابن باجة‎), was an Andalusian-Arab Muslim polymath: an astronomer, logician, musician, philosopher, physician, physicist, psychologist, Botany, poet and scientist. He was known in the West by his Latinized name, Avempace. He was born in Zaragoza in what is today Spain and died in Fes, Morocco in 1138. Avempace worked as vizir for Abu Bakr ibn Ibrahim Ibn Tîfilwît, the Almoravid governor of Saragossa. Avempace also wrote poems (panegyrics and 'muwasshahat') for him, and they both enjoyed music and wine. Avempace joined in poetic competitions with the poet al-Tutili. He later worked, for some twenty years, as the vizir of Yahyà ibn Yûsuf Ibn Tashufin, another brother of the Almoravid Sultan Yusuf Ibn Tashufin (died 1143) in Morocco. He was the famous author of the Kitab al-Nabat (The Book of Plants), a popular work on Botany, which defined the sex of Plants.
His philosophic ideas had a clear effect on Ibn Rushd and Albertus Magnus. Most of his writings and book were not completed (or well organized) because of his early death. He had a vast knowledge of Medicine, Mathematics and Astronomy. His main contribution to Islamic Philosophy is his idea on Soul Phenomenology, but unfortunately not completed.
His beloved expressions were Gharib غريب and Mutawahhid متوحد, two approved and popular expressions of Islamic Gnostics.
Ibn Bajjah was also a renowned poet. In his explanation of the Zajal E.G. Gomes writes: "There is some evidence for the belief that it was invented by the famous philosopher and musician known as Avempace. Its chief characteristic being that it is written entirely in the vernacular. ” (Emilio Gracia Gomes in his essay “Moorish Spain")
Though many of his works have not survived, his theories on astronomy and physics were preserved by Maimonides and Averroes respectively, which had a subsequent influence on later astronomers and physicists in the Islamic civilization and Renaissance Europe, including Galileo Galilei.

In Islamic astronomy, Maimonides wrote the following on the planetary model proposed by Ibn Bajjah:
"I have heard that Abu Bakr [Ibn Bajja] discovered a system in which no epicycles occur, but eccentric spheres are not excluded by him. I have not heard it from his pupils; and even if it be correct that he discovered such a system, he has not gained much by it, for eccentricity is likewise contrary to the principles laid down by Aristotle.... I have explained to you that these difficulties do not concern the astronomer, for he does not profess to tell us the existing properties of the spheres, but to suggest, whether correctly or not, a theory in which the motion of the stars and planets is uniform and circular, and in agreement with observation."

In his commentary on Aristotle's Meteorology, Ibn Bajjah presented his own theory on the Milky Way galaxy. Aristotle believed the Milky Way to be caused by "the ignition of the fiery exhalation of some stars which were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the world which is continuous with the heavenly motions." On the other hand, Aristotle's Arabic commentator Ibn al-Bitriq considered "the Milky Way to be a phenomenon exclusively of the heavenly spheres, not of the upper part of the atmosphere" and that the "light of those stars makes a visible patch because they are so close." Ibn Bajjah's view differed from both, as he considered "the Milky Way to be a phenomenon both of the spheres above the moon and of the sublunar region." The Stanford Encyclopedia of Philosophy describes his theory and observation on the Milky Way as follows:
"The Milky Way is the light of many stars which almost touch one another. Their light forms a “continuous image” (khayâl muttasil) on the surface of the body which is like a “tent” (takhawwum) under the fierily element and over the air which it covers. Avempace defines the continuous image as the result of refraction (in‛ikâs) and supports its explanation with an observation of a conjunction of two planets, Jupiter and Mars which took place in 500/1106-7. He watched the conjunction and “saw them having an elongate figure” although their figure is circular."

Ibn Bajjah also reported observing "two planets as black spots on the face of the Sun." In the 13th century, the Maragha astronomer Qotb al-Din Shirazi identified this observation as the transit of Venus and Mercury. However, Ibn Bajjah cannot have observed a Venus transit, as there were no Venus transits in his lifetime.

In Islamic physics, Ibn Bajjah's law of motion was equivalent to the principle that uniform motion implies absence of action by a force. This principle would later form the basis of modern mechanics and have a subsequent influence on the classical mechanics of physicists such as Galileo Galilei. Ibn Bajjah's definition of velocity was also equivalent to Galileo's definition of velocity:

Velocity = Motive Power - Material Resistance

where the motive power is measured by the specific gravity of the mobile body and the material resistance is the resisting medium whose resistive power is measured by its specific gravity.
Ibn Bajjah was among the first to state that there is always a reaction force for every force exerted, a precursor to Gottfried Leibniz's idea of force which underlies Newton's third law of motion or law of reciprocal actions. However,the history of the principle of action and reaction can be traced as far as Aristotle.

Ibn Bajjah also had an influence on Thomas Aquinas' analysis of motion. In his Systeme du Monde, the pioneering historian of medieval science, Pierre Duhem, stated:
"For the first time we have seen human reason distinguish two elements in a heavy body: the motive force, that is, in modern terms, the weight; and the moved thing, the corpus quantum, or as we say today, the mass. For the first time we have seen the notion of mass being introduced in mechanics, and being introduced as equivalent to what remains in a body when one has suppressed all forms in order to leave only the prime matter quantified by its determined dimensions. Saint Thomas Aquinas's analysis, completing Ibn Bajja's, came to distinguish three notions in a falling body: the weight, the mass, and the resistance of the medium, about which physics will reason during the modern era....This mass, this quantified body, resists the motor attempting to transport it from one place to another, stated Thomas Aquinas."

In Islamic psychology, Ibn Bajjah "based his psychological studies on physics." In his essay, Recognition of the Active Intelligence, he wrote that active intelligence is the most important ability of human beings, and he wrote many other essays on sensations and imaginations. He concluded that "knowledge cannot be acquired by senses alone but by Active Intelligence, which is the governing intelligence of nature." He begins his discussion of the soul with the definition that "bodies are composed of matter and form and intelligence is the most important part of man—sound knowledge is obtained through intelligence, which alone enables one to attain prosperity and build character." He viewed the unity of the rational soul as the principle of the individual identity, and that by its contact with the Active Intelligence, it "becomes one of those lights that gives glory to God." His definition of freedom is "that when one can think and act rationally". He also writes that "the aim of life should be to seek spiritual knowledge and make contact with Active Intelligence and thus with the Divine."

Sunday, May 16, 2010


Pan-STARRS (an acronym for Panoramic Survey Telescope And Rapid Response System) is a planned astronomical survey that will conduct astrometry and photometry of much of the entire sky on a continuous basis. By detecting any differences from previous observations of the same areas of the sky, it is expected to discover a very large number of new asteroids, comets, variable stars and other celestial objects. Its primary mission is to detect near-Earth objects that threaten to cause impact events. It is expected to create a database of all objects visible from Hawaii (three-quarters of the entire sky) down to apparent magnitude 24.
Pan-STARRS' first telescope, called PS1, is located at the summit of Haleakala in Maui Island, and went online on December 6, 2008, under the administration of the University of Hawaii. The other three telescopes completing the array will be completed by 2012 at a total cost of USD 100 million for the entire array.
The Pan-STARRS is a collaboration between the University of Hawaii Institute for Astronomy, MIT Lincoln Laboratory, Maui High Performance Computing Center and Science Applications International Corporation. Telescope construction is funded by the US Air Force. Once PS1 reaches the milestone of passing its Operational Readiness Review, expected Fall 2008, the Pan-STARRS Project will focus on building PS4.
The operations for the first Pan-STARRS telescope (PS1) are funded by The PS1 Science Consortium or PS1SC a consortium including the Max Planck Society in Germany, National Central University in Taiwan, Edinburgh, Durham and Queen's Belfast Universities in the UK, and Johns Hopkins and Harvard Universities in the USA and the Las Cumbres Observatory Global Telescope Network.

Systematically surveying the entire sky on a continuous basis is an unprecedented project and is expected to produce a dramatically larger number of discoveries of various types of celestial objects. For instance, the current leading asteroid discovery project Catalina Sky Survey only goes down to apparent magnitude 20-20.5 and concentrates its searches mostly near the ecliptic; Pan-STARRS will go four magnitudes fainter and cover the entire sky visible from Hawaii. The ongoing survey will also complement the efforts to map the infrared sky by the NASA WISE orbital telescope, with the results of one survey complementing and extending the other.

Solar system
In addition to the large number of expected discoveries in the main asteroid belt, Pan-STARRS is expected to detect at least 100,000 Jupiter Trojan asteroids (compared to 2900 known as of end-2008); at least 20,000 Kuiper belt objects (compared to 800 known as of mid-2005); thousands of Trojan asteroids of Saturn, Uranus and Neptune (currently six Neptune Trojans are known, and none for the other planets excluding Mars and Jupiter); and large numbers of Centaurs and comets.
Apart from drastically adding to the number of known solar system objects, Pan-STARRS will remove or mitigate the observational bias inherent in many current surveys. For instance, among currently known objects there is a bias favoring low orbital inclination, and thus an object such as Makemake escaped detection until recently despite its bright apparent magnitude of 17, which is not much fainter than Pluto. Also, among currently known comets there is a bias favoring those with short perihelion distances. Reducing the effects of this observational bias will enable a more complete picture of solar system dynamics. For instance it is expected that the number of Jupiter Trojans larger than 1 km may in fact roughly match the number of main asteroid belt objects, although the currently known population of the latter is several orders of magnitude larger.
One intriguing possibility is that Pan-STARRS may detect "interstellar debris" or "interstellar interlopers" flying through the solar system. During the formation of a planetary system it is thought that a very large number of objects are ejected due to gravitational interactions with planets (as many as 1013 such objects in the case of our solar system). Objects ejected by planetary systems around other stars might plausibly be flying throughout the galaxy and some may pass through our solar system.
Another intriguing possibility is that Pan-STARRS may actually detect collisions involving small asteroids. These are quite rare and none have yet been observed, but with the drastically larger number of asteroids that will be discovered it is expected from statistical considerations that some collision events may be observed.
Pan-STARRS will also likely detect a number of Kuiper belt objects the size of Pluto or larger, similar to Eris.

Beyond the solar system
It is expected that Pan-STARRS will discover an extremely large number of variable stars, including such stars in other nearby galaxies; in fact, this may lead to the discovery of hitherto unknown dwarf galaxies. In discovering a large number of Cepheid variables and eclipsing binary stars, it will help determine distances to nearby galaxies with greater precision. It is expected to discover a large number of Type Ia supernovae in other galaxies, which are important in studying the effects of dark energy, and also optical afterglows of gamma ray bursts.
Because very young stars (such as T Tauri stars) are usually variable, Pan-STARRS should discover a large number of these and improve our understanding of them. It is also expected that Pan-STARRS may discover a large number of extrasolar planets by observing their transits across their parent stars, as well as gravitational microlensing events.
Pan-STARRS will also measure proper motion and parallax and should thereby discover a large number of brown dwarfs and white dwarfs and other nearby faint objects, and it should be able to conduct a complete census of all stars within 100 parsecs of the Sun. Prior proper motion and parallax surveys often did not detect faint objects such as the recently-discovered Teegarden's star, which are too faint for projects such as Hipparcos.
Also, by identifying stars with large parallax but very small proper motion for followup radial velocity measurements, Pan-STARRS may even be able to permit the detection of hypothetical Nemesis-type objects if these actually exist.

SN 2008id (type 1a supernova), confirmed by Keck observatory via redshift.

Sunday, May 9, 2010


Paracetamol (INN) (pronounced /ˌpærəˈsiːtəmɒl, ˌpærəˈsɛtəmɒl/) or acetaminophen (/əˌsiːtəˈmɪnɵfɨn/ ( listen)) (USAN) is a widely used over-the-counter analgesic (pain reliever) and antipyretic (fever reducer).
It is commonly used for the relief of headaches, and other minor aches and pains, and is a major ingredient in numerous cold and flu remedies. In combination with opioid analgesics, paracetamol could be used also in the management of more severe pain (such as in advanced cancer).
While generally safe for use at recommended doses (1,000 mg per single dose and up to 4,000 mg per day for adults, up to 2,000 mg per day if drinking alcohol), acute overdoses of paracetamol can cause potentially fatal liver damage and, in rare individuals, a normal dose can do the same; the risk is heightened by alcohol consumption. Paracetamol toxicity is the foremost cause of acute liver failure in the Western world, and accounts for most drug overdoses in the United States, the United Kingdom, Australia and New Zealand.
Paracetamol is part of the class of drugs known as "aniline analgesics"; it is the only such drug still in use today. It is the active metabolite of phenacetin, once popular as an analgesic and antipyretic in its own right, but unlike phenacetin and its combinations, paracetamol is not considered to be carcinogenic at therapeutic doses. The words acetaminophen (used in the United States, Canada, Hong Kong, Iran, Colombia and other Latin American countries) and paracetamol (used elsewhere) both come from chemical names for the compound: para-acetylaminophenol and para-acetylaminophenol. In some contexts, it is simply abbreviated as APAP, for N-acetyl-para-aminophenol.
There is confusion in terminology of paracetamol. It could be considered a nonsteroidal antiinflammatory drug (NSAID), but paracetamol has very little anti-inflammatory effect in many tissues. However, aspirin, paracetamol and other NSAIDs all act by the same mechanism (inhibition of prostaglandin (PG) synthesis) and all show varying levels of analgesic, anti-inflammatory, antipyretic and antiplatelet actions.

The World Health Organization (WHO) recommends that paracetamol be given to children with fever higher than 38.5 °C (101.3 °F).
Paracetamol is much more effective than aspirin, especially in patients where excessive gastric acid secretion or prolongation of bleeding time may be a concern. While paracetamol has analgesic and antipyretic properties comparable to those of aspirin, its anti-inflammatory effects are weak. Because paracetamol is well tolerated, available without a prescription, and lacks the gastric side effects of aspirin, it has in recent years increasingly become a common household drug.
Acetaminophen is used for the relief of fevers, aches and pains associated with many parts of the body. Acetaminophen relieves pain in mild arthritis but has no effect on the underlying inflammation, redness, and swelling of the joint. If the pain is not due to inflammation, acetaminophen is as effective as aspirin. It is as effective as the non-steroidal antiinflammatory drug ibuprofen (Motrin) in relieving the pain of osteoarthritis of the knee. Unless directed by physician, acetaminophen should not be used for longer than 10 days.

Efficacy and side effects
Paracetamol, unlike other common analgesics such as aspirin and ibuprofen, has relatively little anti-inflammatory activity, so it is not considered to be a non-steroidal anti-inflammatory drug (NSAID).

Regarding comparative efficacy, studies show conflicting results when compared to NSAIDs. A randomized controlled trial of chronic pain from osteoarthritis in adults found similar benefit from paracetamol and ibuprofen.
A randomized controlled trial of acute musculoskeletal pain in children found that the standard OTC dose of ibuprofen gives greater relief of pain than the standard dose of paracetamol. Another study has questioned the benefits of this drug as an antipyretic in children

Adverse effects
In recommended doses, paracetamol does not irritate the lining of the stomach, affect blood coagulation as much as NSAIDs, or affect function of the kidneys. However, some studies have shown that high dose-usage (greater than 2,000 mg per day) does increase the risk of upper gastrointestinal complications such as stomach bleeding. The researchers found that heavy use of aspirin or paracetamol - defined as 300 grams a year (1 g per day on average) - was linked to a condition known as small, indented and calcified kidneys (SICK). Paracetamol is safe in pregnancy, and does not affect the closure of the fetal ductus arteriosus as NSAIDs can. Unlike aspirin, it is safe in children, as paracetamol is not associated with a risk of Reye's syndrome in children with viral illnesses.
Like NSAIDs and unlike opioid analgesics, paracetamol has not been found to cause euphoria or alter mood in any way. In 2008, the largest study to date on the long term side effects of paracetamol in children was published in The Lancet. Conducted on over 200,000 children in 31 countries, the study found that the use of paracetamol for fever in the first year of life was associated with an increase in the incidence of asthmatic symptoms at 6–7 years, and that paracetamol use, both in the first year of life and in children aged 6–7 years, was associated with an increased incidence of rhinoconjunctivitis and eczema. The authors acknowledged that their "findings might have been due to confounding by indication", i.e. that the association may not be causal but rather due to the disease being treated with paracetamol, and emphasized that further research was needed. Furthermore a number of editorials, comments, correspondence and their replies have been published in The Lancet concerning the methodology and conclusions of this study. The UK regulatory body the Medicines and Healthcare products Regulatory Agency, also reviewed this research and published a number of concerns over data interpretation, and offer the following advice for healthcare professionals, parents, and carers: "The results of this new study do not necessitate any change to the current guidance for use in children. Paracetamol remains a safe and appropriate choice of analgesic in children. There is insufficient evidence from this research to change guidance regarding the use of antipyretics in children."
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