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#1 Re: Exercises » Compute the solution: » Today 13:44:44
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#3 This is Cool » Influenza » Yesterday 17:31:18
- Jai Ganesh
- Replies: 0
Influenza
Gist
Influenza, or the flu, is a contagious respiratory illness caused by influenza viruses, with common symptoms including fever, cough, sore throat, muscle aches, and fatigue. While many people recover on their own, it can lead to severe complications. The best prevention is an annual flu vaccine, but other measures include frequent hand washing and avoiding close contact with sick individuals.
The flu typically lasts for a week or two, but symptoms can vary in duration. While most acute symptoms like fever and body aches usually improve within 3 to 7 days, a cough and fatigue can linger for two weeks or longer. It's important to monitor your symptoms, as some people, especially those in high-risk groups, may develop complications or require medical attention.
Is influenza contagious?
Yes, influenza is a contagious respiratory illness that spreads easily from person to person through respiratory droplets from coughs and sneezes. It is highly contagious, and a person can spread the virus from about one day before feeling sick until about five to seven days after symptoms begin. Staying home when sick and practicing good hygiene are key to preventing its spread.
Summary:
Overview
Comparison of COVID-19, cold and flu symptoms. Shared symptoms can include sore throat, cough, fever, body aches and more.
The flu, common cold and COVID-19 have similar symptoms. The flu and COVID-19 can be severe, but colds rarely are.
What is the flu (influenza)?
The flu is an illness you get from the influenza virus. It causes symptoms like head and body aches, sore throat, fever and respiratory symptoms, which can be severe. Flu is most common in winter months, when many people can get sick at once (an epidemic).
When is flu season?
Flu season — when cases of the flu go up dramatically — in the Northern Hemisphere (which includes the U.S.) is October through May. The highest number of cases (peak) usually happen between December and February.
How common is the flu?
The flu is one of the most common infectious diseases. Every flu season, about 20 to 40 million people in the U.S. catch the flu.
What is the difference between the flu and the common cold?
The flu and the common cold can have similar symptoms, like runny nose and cough. But cold symptoms are usually mild and flu symptoms can be severe and lead to serious complications.
Different viruses cause colds and the flu.
How do I know if I have the flu or COVID-19?
Since they have similar symptoms, the only way to know for sure if you have the flu or COVID-19 is to get tested. They both have a risk of serious illness. But different viruses cause these infections, and providers treat them with different medications.
Who is at higher risk for complications from the flu?
Certain health conditions can put you at higher risk for severe illness from the flu. This includes life-threatening complications that require hospitalization. You’re at higher risk for serious illness if you:
* Have asthma, COPD or another chronic lung disease.
* Have a history of kidney, liver, neurological, heart or blood vessels disease, including stroke.
* Have a condition that causes issues with muscle function or makes it difficult to cough, swallow or clear fluids from your airways.
* Have diabetes.
* Have a weakened immune system (from HIV/AIDS, cancer or immunosuppressive medications).
* Have a blood disorder, like sickle cell disease.
* Have a BMI greater than 30 (have obesity).
* Are under 5 years old or over 65 years old.
* Are pregnant.
* Are under 19 years old and take aspirin regularly.
* Live in a long-term care facility.
* Non-Hispanic Black people, non-Hispanic American Indians, Alaska Native people and Hispanic or Latino people have the highest rates of severe illness from the flu compared to non-Hispanic White people and non-Hispanic Asian people.
Symptoms and Causes
With so many symptoms in common, it can be hard to tell the difference between a cold and the flu. Here’s how to tell which is which.
* What are the symptoms of the flu?
Symptoms of the flu usually come on quickly, and can include:
* Fever.
* Chills.
* Body aches.
* Cough.
* Headache.
* Sore throat.
* Runny or stuffy nose (congestion).
* Tiredness or feeling run down.
* Diarrhea or vomiting (usually only in kids).
You may not have all of these symptoms.
What causes the flu?
The influenza virus causes flu. Influenza A, B and C are the most common types that infect people. Influenza A and B are seasonal (most people get them in the winter) and have more severe symptoms. Influenza C doesn’t cause severe symptoms and it’s not seasonal — the number of cases stays about the same throughout the year.
H1N1 (“swine flu”) and bird flu are both subtypes of influenza A.
Details
Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin one to four (typically two) days after exposure to the virus and last for about two to eight days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia from the virus or a subsequent bacterial infection. Other complications include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease.
There are four types of influenza virus: types A, B, C, and D. Aquatic birds are the primary source of influenza A virus (IAV), which is also widespread in various mammals, including humans and pigs. Influenza B virus (IBV) and influenza C virus (ICV) primarily infect humans, and influenza D virus (IDV) is found in cattle and pigs. Influenza A virus and influenza B virus circulate in humans and cause seasonal epidemics, and influenza C virus causes a mild infection, primarily in children. Influenza D virus can infect humans but is not known to cause illness. In humans, influenza viruses are primarily transmitted through respiratory droplets from coughing and sneezing. Transmission through aerosols and surfaces contaminated by the virus also occur.
Frequent hand washing and covering one's mouth and nose when coughing and sneezing reduce transmission, as does wearing a mask. Annual vaccination can help to provide protection against influenza. Influenza viruses, particularly influenza A virus, evolve quickly, so flu vaccines are updated regularly to match which influenza strains are in circulation. Vaccines provide protection against influenza A virus subtypes H1N1 and H3N2 and one or two influenza B virus subtypes. Influenza infection is diagnosed with laboratory methods such as antibody or antigen tests and a polymerase chain reaction (PCR) to identify viral nucleic acid. The disease can be treated with supportive measures and, in severe cases, with antiviral drugs such as oseltamivir. In healthy individuals, influenza is typically self-limiting and rarely fatal, but it can be deadly in high-risk groups.
In a typical year, five to 15 percent of the population contracts influenza. There are 3 to 5 million severe cases annually, with up to 650,000 respiratory-related deaths globally each year. Deaths most commonly occur in high-risk groups, including young children, the elderly, and people with chronic health conditions. In temperate regions, the number of influenza cases peaks during winter, whereas in the tropics, influenza can occur year-round. Since the late 1800s, pandemic outbreaks of novel influenza strains have occurred every 10 to 50 years. Five flu pandemics have occurred since 1900: the Spanish flu from 1918 to 1920, which was the most severe; the Asian flu in 1957; the Hong Kong flu in 1968; the Russian flu in 1977; and the swine flu pandemic in 2009.
Signs and symptoms
Symptoms of influenza, with fever and cough the most common symptoms.
The symptoms of influenza are similar to those of a cold, although usually more severe and less likely to include a runny nose. The time between exposure to the virus and development of symptoms (the incubation period) is one to four days, most commonly one to two days. Many infections are asymptomatic. The onset of symptoms is sudden, and initial symptoms are predominately non-specific, including fever, chills, headaches, muscle pain, malaise, loss of appetite, lack of energy, and confusion. These are usually accompanied by respiratory symptoms such as a dry cough, sore or dry throat, hoarse voice, and a stuffy or runny nose. Coughing is the most common symptom. Gastrointestinal symptoms may also occur, including nausea, vomiting, diarrhea, and gastroenteritis, especially in children. The standard influenza symptoms typically last for two to eight days. Some studies suggest influenza can cause long-lasting symptoms in a similar way to long COVID.
Symptomatic infections are usually mild and limited to the upper respiratory tract, but progression to pneumonia is relatively common. Pneumonia may be caused by the primary viral infection or a secondary bacterial infection. Primary pneumonia is characterized by rapid progression of fever, cough, labored breathing, and low oxygen levels that cause bluish skin. It is especially common among those who have an underlying cardiovascular disease such as rheumatic heart disease. Secondary pneumonia typically has a period of improvement in symptoms for one to three weeks[ followed by recurrent fever, sputum production, and fluid buildup in the lungs, but can also occur just a few days after influenza symptoms appear. About a third of primary pneumonia cases are followed by secondary pneumonia, which is most frequently caused by the bacteria Streptococcus pneumoniae and Staphylococcus aureus.
Additional Information
Influenza, or the flu, is a contagious respiratory illness caused by influenza viruses, with common symptoms including fever, cough, sore throat, muscle aches, and fatigue. While many people recover on their own, it can lead to severe complications. The best prevention is an annual flu vaccine, but other measures include frequent hand washing and avoiding close contact with sick individuals.
Symptoms
* Sudden onset of fever
* Dry cough
* Sore throat
* Runny nose
* Headache
* Muscle and joint pain
* Severe malaise (feeling unwell)
* Fatigue
Prevention
Vaccination: Get a flu shot every year, as it is the most effective way to prevent the flu and its complications.
Hygiene: Wash your hands frequently with soap and water or use an alcohol-based hand sanitizer.
Avoid contact: Stay away from sick people and avoid touching your face.
Treatment
Rest: Get plenty of rest and stay warm to allow your body to fight the virus.
Hydration: Drink plenty of liquids like water, juice, and warm soups.
Pain relievers: Over-the-counter pain relievers can help manage fever, headaches, and body aches, but children and teenagers should not be given aspirin due to the risk of Reye's syndrome.
Medical attention: Seek medical attention, especially if you are in a high-risk group, or if you develop severe symptoms like difficulty breathing or chest pain. In some cases, a doctor may prescribe antiviral drugs.
#4 Re: Dark Discussions at Cafe Infinity » crème de la crème » Yesterday 16:39:42
2389) Robert S. Mulliken
Gist:
Work
The world around us consists of molecules that are composed of atoms. In Niels Bohr’s atomic model, which is based on principles of quantum physics, electrons circle the atomic nucleus in different shells that contain a fixed number of electrons. The assumption was that attractive forces between the atoms in a molecule are the result of atoms sharing electrons to fill the electron shells. Beginning in the mid-1920s, Robert Mulliken applied quantum mechanics to the development of sophisticated models for the movement of electrons within a molecule, so-called molecular orbitals.
Summary
Robert Sanderson Mulliken (born June 7, 1896, Newburyport, Mass., U.S.—died Oct. 31, 1986, Arlington, Va.) was an American chemist and physicist who received the 1966 Nobel Prize for Chemistry for “fundamental work concerning chemical bonds and the electronic structure of molecules.”
A graduate of the Massachusetts Institute of Technology, Mulliken worked, during World War I and for a few years afterward, in government chemical research. He then studied under the physicist Robert A. Millikan at the University of Chicago, receiving his Ph.D. in 1921. He taught at New York University (1926–28) and then joined the faculty of the University of Chicago (1928–85).
Mulliken began working on his theory of molecular structure in the 1920s. He theoretically systematized the electron states of molecules in terms of molecular orbitals. Departing from the idea that electron orbitals for atoms are static and that atoms combine like building blocks to form molecules, he proposed that, when molecules are formed, the atoms’ original electron configurations are changed into an overall molecular configuration. Further extending his theory, he developed (1952) a quantum-mechanical theory of the behaviour of electron orbitals as different atoms merge to form molecules.
During World War II Mulliken worked on the Plutonium Project, part of the development of the atomic bomb, at the University of Chicago. In 1955 he served as scientific attaché at the U.S. embassy in London.
Details
Robert Sanderson Mulliken ForMemRS[1] (June 7, 1896 – October 31, 1986) was an American physical chemist, primarily responsible for the early development of molecular orbital theory, i.e. the elaboration of the molecular orbital method of computing the structure of molecules. Mulliken received the Nobel Prize in Chemistry in 1966 and the Priestley Medal in 1983.[2]
Early years
Robert Mulliken was born in Newburyport, Massachusetts on June 7 1896. His father, Samuel Parsons Mulliken, was a professor of organic chemistry at the Massachusetts Institute of Technology. As a child, Robert Mulliken learned the name and botanical classification of plants and, in general, had an excellent, but selective, memory. For example, he learned German well enough to skip the course in scientific German in college, but could not remember the name of his high school German teacher. He also made the acquaintance, while still a child, of the physical chemist Arthur Amos Noyes.
Mulliken helped with some of the editorial work when his father wrote his four-volume text on organic compound identification, and thus became an expert on organic chemical nomenclature.
Education
In high school in Newburyport, Mulliken followed a scientific curriculum. He graduated in 1913 and succeeded in getting a scholarship to MIT which had earlier been won by his father. Like his father, he majored in chemistry. Already as an undergraduate, he conducted his first publishable research: on the synthesis of organic chlorides. Because he was unsure of his future direction, he included some chemical engineering courses in his curriculum and spent a summer touring chemical plants in Massachusetts and Maine. He received his B. S. degree in chemistry from MIT in 1917.
Early career
At this time, the United States had just entered World War I, and Mulliken took a position at American University in Washington, D.C., making poison gas under James B. Conant. After nine months, he was drafted into the Army's Chemical Warfare Service, but continued on the same task. His laboratory techniques left much to be desired, and he was out of service for months with burns. Later, he contracted a bad case of influenza, and was still hospitalized at war's end.
After the war, he took a job investigating the effects of zinc oxide and carbon black on rubber, but quickly decided that this was not the kind of chemistry he wanted to pursue. Hence, in 1919 he entered the Ph.D. program at the University of Chicago.
Graduate and early postdoctoral education
Mulliken got his doctorate in 1921 based on research into the separation of isotopes of mercury by evaporation, and continued in his isotope separation by this method. While at Chicago, he took a course under the Nobel Prize-winning physicist Robert A. Millikan, which exposed him to the old quantum theory. He also became interested in strange molecules after exposure to work by Hermann I. Schlesinger on diborane.
At Chicago, he had received a grant from the National Research Council (NRC) which had paid for much of his work on isotope separation. The NRC grant was extended in 1923 for two years so he could study isotope effects on band spectra of such diatomic molecules as boron nitride (BN) (comparing molecules with B10 and B11). He went to Harvard University to learn spectrographic technique from Frederick A. Saunders and quantum theory from E. C. Kemble. At the time, he was able to associate with J. Robert Oppenheimer and many future Nobel laureates, including John H. Van Vleck and Harold C. Urey. He also met John C. Slater, who had worked with Niels Bohr.
In 1925 and 1927, Mulliken traveled to Europe, working with outstanding spectroscopists and quantum theorists such as Erwin Schrödinger, Paul A. M. Dirac, Werner Heisenberg, Louis de Broglie, Max Born, and Walther Bothe (all of whom eventually received Nobel Prizes) and Friedrich Hund, who was at the time Born's assistant. They all, as well as Wolfgang Pauli, were developing the new quantum mechanics that would eventually supersede the old quantum theory. Mulliken was particularly influenced by Hund, who had been working on quantum interpretation of band spectra of diatomic molecules, the same spectra which Mulliken had investigated at Harvard. In 1927 Mulliken worked with Hund and as a result developed his molecular orbital theory, in which electrons are assigned to states that extend over an entire molecule. In consequence, molecular orbital theory was also referred to as the Hund-Mulliken theory.
Early scientific career
From 1926 to 1928, he taught in the physics department at New York University (NYU). This was his first recognition as a physicist. Though his work had been considered important by chemists, it clearly was on the borderline between the two sciences and both would claim him from this point on. Then he returned to the University of Chicago as an associate professor of physics, being promoted to full professor in 1931. He ultimately held a position jointly in both the physics and chemistry departments. At both NYU and Chicago, he continued to refine his molecular-orbital theory.
Up to this point, the primary way to calculate the electronic structure of molecules was based on a calculation by Walter Heitler and Fritz London on the hydrogen molecule (H2) in 1927. With the conception of hybridized atomic orbitals by John C. Slater and Linus Pauling, which rationalized observed molecular geometries, the method was based on the premise that the bonds in any molecule could be described in a manner similar to the bond in H2, namely, as overlapping atomic orbitals centered on the atoms involved. Since it corresponded to chemists' ideas of localized bonds between pairs of atoms, this method (called the Valence-Bond (VB) or Heitler-London-Slater-Pauling (HLSP) method), was very popular. In attempting to calculate the properties of excited states (molecules that have been excited by an energy source), the VB method does not always work well. With its description of the electron wave functions in molecules as delocalized molecular orbitals that possess the same symmetry as the molecule, Hund and Mulliken's molecular-orbital method, including contributions by John Lennard-Jones, proved to be more flexible and applicable to a vast variety of types of molecules and molecular fragments, and has eclipsed the valence-bond method. As a result of this development, he received the Nobel Prize in Chemistry in 1966.
Mulliken became a member of the National Academy of Sciences in 1936, the youngest member in the organization's history at the time. He was elected to the American Philosophical Society in 1940 and the American Academy of Arts and Sciences in 1965. He was elected a Foreign Member of the Royal Society (ForMemRs) in 1967.
Mulliken population analysis is named after him, a method of assigning charges to atoms in a molecule.
Personal life
On December 24, 1929, he married Mary Helen von Noé, daughter of Adolf Carl Noé, a geology professor at the University of Chicago. They had two daughters.
Later years
In 1934, he derived a new scale for measuring the electronegativity of elements, which he defined as the average of an atom's ionization enthalpy and electron affinity. This does not entirely correlate with the scale of Linus Pauling, but is generally in close correspondence.
In World War II, from 1942 to 1945, he directed the Information Office for the University of Chicago's Plutonium project. Afterward, he developed mathematical formulas to enable the progress of the molecular-orbital theory.
In 1952. he began to apply quantum mechanics to the analysis of the reaction between Lewis acid and base molecules. In 1961, he became Distinguished Professor of Physics and Chemistry at Florida State University, and continued in his studies of molecular structure and spectra, ranging from diatomic molecules to large complex aggregates. In 1981, Mulliken became a founding member of the World Cultural Council. In 1983, Mulliken received the Golden Plate Award of the American Academy of Achievement. He retired in 1985. His wife died in 1975.
At the age of 90, Mulliken died of congestive heart failure at his daughter's home in Arlington County, Virginia on October 31, 1986. His body was returned to Chicago for burial.
#5 Re: Dark Discussions at Cafe Infinity » Greatest Mathematicians from 1 CE ... » Yesterday 16:19:48
25) John Napier
John Napier of Merchiston (Latinized as Ioannes Neper; 1 February 1550 – 4 April 1617), nicknamed Marvellous Merchiston, was a Scottish landowner known as a mathematician, physicist, and astronomer. He was the 8th Laird of Merchiston. Napier is best known as the discoverer of logarithms. He also invented the "Napier's bones" calculating device and popularised the use of the decimal point in arithmetic.
Napier's birthplace, Merchiston Tower in Edinburgh, is now part of the facilities of Edinburgh Napier University. There is a memorial to him at St Cuthbert's Parish Church at the west end of Princes Street Gardens in Edinburgh.
Life
Napier's father was Sir Archibald Napier of Merchiston Castle, and his mother was Janet Bothwell, daughter of the politician and judge Francis Bothwell, and a sister of Adam Bothwell who became the Bishop of Orkney. Archibald Napier was 16 years old when John Napier was born.
There are no records of Napier's early learning, but many believe that he was privately tutored during early childhood. At age 13, he was enrolled in St Salvator's College, St Andrews. Near the time of his matriculation the quality of the education provided by the university was poor, owing in part to the Reformation's causing strife between those of the old faith and the growing numbers of Protestants. There are no records showing that John Napier completed his education at St Andrews. It is believed he left Scotland to further his education in mainland Europe, following the advice given by his uncle Adam Bothwell in a letter written to John Napier's father on 5 December 1560, saying, "I pray you, sir, to send John to the schools either to France or Flanders, for he can learn no good at home". It is not known which university Napier attended in Europe, but when he returned to Scotland in 1571 he was fluent in Greek, a language that was not commonly taught in European universities at the time. There are also no records showing his enrollment in the premier universities in Paris or Geneva during this time.
In 1571, Napier, aged 21, returned to Scotland, and bought a castle at Gartness in 1574. On the death of his father in 1608, Napier and his family moved into Merchiston Castle in Edinburgh, where he resided the remainder of his life. He had a property within Edinburgh city as well on Borthwick's Close off the Royal Mile.
On 7 June 1596 Napier wrote a paper Secret inventions, profitable and necessary in these days for defence of this island. He describes two kinds of burning mirror for use against ships at a distance, a special kind of artillery shot, and a musket-proof metal chariot.
Napier died from the effects of gout at home at Merchiston Castle at the age of 67. He was buried in the kirkyard of St Giles in Edinburgh. Following the loss of the kirkyard of St Giles to build Parliament House, his remains were transferred to an underground vault on the north side of St Cuthbert's Parish Church at the west side of Edinburgh. There is also a wall monument to Napier at St Cuthbert's.
Napier, like many mathematicians at the time, worked on methods to reduce the labour required for calculations, and he became famous for the devices that he invented to assist with these issues of computation, for example the numbering rods more quaintly known as "Napier's bones".
In addition, Napier recognised the potential of the recent developments in mathematics, particularly those of prosthaphaeresis, decimal fractions, and symbolic index arithmetic, to tackle the issue of reducing computation. He appreciated that, for the most part, practitioners who had laborious computations generally did them in the context of trigonometry. Therefore, as well as developing the logarithmic relation, Napier set it in a trigonometric context so it would be even more relevant.
#6 Re: This is Cool » Miscellany » Yesterday 15:58:54
2441) Heavy Water
Gist
Heavy water, or deuterium oxide (D2O), is a form of water where the hydrogen atoms are replaced with deuterium, a stable isotope of hydrogen with an extra neutron. It is denser than ordinary water and has a higher boiling point and freezing point. Heavy water's primary use is as a moderator and coolant in nuclear reactors, but it also has other applications in fields like medicine and life sciences.
Heavy water is a form of water with a unique atomic structure and properties coveted for the production of nuclear power and weapons. Like ordinary water—H20—each molecule of heavy water contains two hydrogen atoms and one oxygen atom. The difference, though, lies in the hydrogen atoms.
Summary
Heavy water (deuterium oxide, 2H2O, D2O) is a form of water in which hydrogen atoms are all deuterium (2H or D, also known as heavy hydrogen) rather than the common hydrogen-1 isotope (1H, also called protium) that makes up most of the hydrogen in normal water. The presence of the heavier isotope gives the water different nuclear properties, and the increase in mass gives it slightly different physical and chemical properties when compared to normal water.
Deuterium is a heavy hydrogen isotope. Heavy water contains deuterium atoms and is used in nuclear reactors. Semiheavy water (HDO) is more common than pure heavy water, while heavy-oxygen water is denser but lacks unique properties. Tritiated water is radioactive due to tritium content.
Heavy water has different physical properties from regular water, such as being 10.6% denser and having a higher melting point. Heavy water is less dissociated at a given temperature, and it does not have the slightly blue color of regular water. It can taste slightly sweeter than regular water, though not to a significant degree. Heavy water affects biological systems by altering enzymes, hydrogen bonds, and cell division in eukaryotes. It can be lethal to multicellular organisms at concentrations over 50%. However, some prokaryotes like bacteria can survive in a heavy hydrogen environment. Heavy water can be toxic to humans, but a large amount would be needed for poisoning to occur.
The most cost-effective process for producing heavy water is the Girdler sulfide process. Heavy water is used in various industries and is sold in different grades of purity. Some of its applications include nuclear magnetic resonance, infrared spectroscopy, neutron moderation, neutrino detection, metabolic rate testing, neutron capture therapy, and the production of radioactive materials such as plutonium and tritium.
Details
Heavy water, or deuterium oxide (D2O), is a form of water where the hydrogen atoms are replaced with deuterium, a stable isotope of hydrogen with an extra neutron. It is denser than ordinary water and has a higher boiling point and freezing point. Heavy water's primary use is as a moderator and coolant in nuclear reactors, but it also has other applications in fields like medicine and life sciences.
Heavy water (D2O) is water composed of two atoms of deuterium, the hydrogen isotope with a mass double that of ordinary hydrogen, and one atom of oxygen. (Ordinary water has a composition represented by H2O.) Thus, heavy water has a molecular weight of about 20 (the sum of twice the atomic weight of deuterium, which is 2, plus the atomic weight of oxygen, which is 16), whereas ordinary water has a molecular weight of about 18 (twice the atomic weight of ordinary hydrogen, which is 1, plus oxygen, which is 16).
As obtained from most natural sources, ordinary water contains about one deuterium atom for every 6,760 ordinary hydrogen atoms. Continued electrolysis of hundreds of liters of water until only a few milliliters remain yields practically pure deuterium oxide. This operation, until 1943 the only large-scale method used, has been superseded by less expensive processes, such as the Girdler sulfide process (deuterium is exchanged between hydrogen sulfide [H2S] and water) and fractional distillation (D2O becomes concentrated in the liquid residue because it is less volatile than H2O). The heavy water produced is used as a moderator of neutrons in nuclear power plants. In the laboratory heavy water is employed as an isotopic tracer in studies of chemical and biochemical processes.
Additional Information
Deuterium oxide, also known as “heavy water” or “deuterium water”, is the compound of oxygen and the heavy isotope of hydrogen, called deuterium. Physically and chemically, heavy water is almost identical to ordinary “light” water, H2O. It is called heavy water because its density is greater than H2O. Its chemical formula is D2O.
Deuterium contains one neutron and one proton in its nucleus, which makes it twice as heavy as protium (hydrogen), which contains only one proton. Deuterium oxide is a colorless and odorless liquid at normal temperature and pressure. Compared to ordinary water, its chemical characteristic is relatively inactive with a specific gravity of 1.10775 (at 25℃), melting/freezing point of 3.82℃, and a boiling point of 101.42℃. The hydrogen bond strength and degree of association between heavy water molecules are both stronger than that of ordinary water molecules.
#7 Science HQ » Meitnerium » Yesterday 15:34:06
- Jai Ganesh
- Replies: 0
Meitnerium
Gist
Meitnerium has no practical or commercial uses because it is an extremely rare, highly radioactive element with a very short half-life, meaning only a few atoms have ever been produced. Its sole purpose is for scientific research, particularly in the fields of nuclear physics and the study of superheavy elements to understand atomic nuclei, nuclear reaction dynamics, and the extension of the periodic table.
It has never been found naturally and only a small number of atoms have been produced in laboratories. Its chemistry and appearance are not known with any certainty, although the chemistry is believed to be similar to iridium. Meitnerium is too rare to have any commercial or industrial application.
Summary
Meitnerium is a synthetic chemical element; it has symbol Mt and atomic number 109. It is an extremely radioactive synthetic element (an element not found in nature, but can be created in a laboratory). The most stable known isotope, meitnerium-278, has a half-life of 4.5 seconds, although the unconfirmed meitnerium-282 may have a longer half-life of 67 seconds. The element was first synthesized in August 1982 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, and it was named after the Austrian-Swedish nuclear physicist Lise Meitner in 1997.
In the periodic table, meitnerium is a d-block transactinide element. It is a member of the 7th period and is placed in the group 9 elements, although no chemical experiments have yet been carried out to confirm that it behaves as the heavier homologue to iridium in group 9 as the seventh member of the 6d series of transition metals. Meitnerium is calculated to have properties similar to its lighter homologues, cobalt, rhodium, and iridium.
Details
Meitnerium (Mt) is an artificially produced element belonging to the transuranium group, atomic number 109. It is predicted to have chemical properties resembling those of iridium. The element is named in honour of Austrian-born physicist Lise Meitner.
In 1982 West German physicists at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung [GSI]) in Darmstadt synthesized an isotope of meitnerium with a mass number of 266. Using a high-energy linear accelerator, the GSI investigators, under the direction of Peter Armbruster, bombarded bismuth-209 targets with beams of iron-58 ions for roughly 10 days. The resultant fusion reaction between the bismuth and iron atoms yielded only a single nucleus of the new element; however, the sensitivity of the detection technique employed left little doubt as to the validity of the identification. The most stable isotope, meitnerium-276, has a half-life of 0.72 second.
Additional Information:
Appearance
A highly radioactive metal, of which only a few atoms have ever been made.
Uses
At present it is only used in research.
Biological role
Meitnerium has no known biological role.
Natural abundance
Fewer than 10 atoms of meitnerium have ever been made, and it will probably never be isolated in observable quantities. It is made by bombarding bismuth with iron atoms.
#8 Dark Discussions at Cafe Infinity » Coexistence Quotes » Yesterday 15:10:49
- Jai Ganesh
- Replies: 0
Coexistence Quotes
1. The only alternative to coexistence is codestruction. - Jawaharlal Nehru
2. Prime Minister Sharon, Prime Minister Abbas, I urge you today to end the designs of those who seek destruction, annihilation and occupation, and I urge you to have the will and the courage to begin to realize our dreams of peace, prosperity and coexistence. - Abdullah II of Jordan
3. Germany wants peaceful coexistence of Muslims and members of other religions. - Angela Merkel
4. India's history and destiny, India's legacy and future, are a function of coexistence and conciliation, of reform and reconciliation. - Ram Nath Kovind.
#9 Re: Jai Ganesh's Puzzles » General Quiz » Yesterday 14:42:43
Hi,
#10657. What does the term in Chemistry Electron donor mean?
#10658. What does the term in Biology Electron microscope mean?
#10 Re: Jai Ganesh's Puzzles » English language puzzles » Yesterday 14:21:26
Hi,
#5453. What does the noun gargoyle mean?
#5454. What does the adjective gargantuan mean?
#11 Re: Jai Ganesh's Puzzles » Doc, Doc! » Yesterday 14:02:51
Hi,
#2521. What does the medical term Hartmann's operation mean?
#12 Jokes » Bread Jokes - II » Yesterday 13:52:30
- Jai Ganesh
- Replies: 0
Q: What does bread do after it's done baking?
A: Loaf around.
* * *
Q: What do you call a handsome loaf of bread?
A: Bread Pitt!
* * *
Q: Why was the baker in a panic?
A: He was in a loaf or death situation.
* * *
Q: Why do bakers give women on special occasions?
A: Flours.
* * *
Q: Why is dough another word for money?
A: Because everyone kneads it.
* * *
#13 Re: Jai Ganesh's Puzzles » 10 second questions » Yesterday 13:42:23
Hi,
#9800.
#14 Re: Jai Ganesh's Puzzles » Oral puzzles » Yesterday 13:33:36
Hi,
6295.
#15 Re: Exercises » Compute the solution: » Yesterday 13:21:55
Hi,
2644.
#16 Re: Exercises » Compute the solution: » 2025-11-08 20:12:36
Hi,
Good work!
2643.
#17 This is Cool » Rudder » 2025-11-08 19:27:25
- Jai Ganesh
- Replies: 0
Rudder
Gist
A rudder is a flat, vertical blade at the stern (rear) of a ship that controls its direction by deflecting water flow. When the rudder is turned, the force of the water against it pushes the stern away, causing the ship to turn in the opposite direction. It is operated by a steering wheel or tiller connected to a mechanical or hydraulic system, making it a crucial component for navigation and safety.
A rudder is a control surface used to steer a vessel or aircraft by changing the direction of the fluid (water or air) flowing past it, which in turn creates a turning or yawing motion. In ships, it directly steers the vessel, while in aircraft, it is primarily used to coordinate turns, correct for aerodynamic forces (like "adverse yaw"), and maintain stability, especially during crosswinds.
Summary
A rudder is a part of the steering apparatus of a boat or ship that is fastened outside the hull, usually at the stern. The most common form consists of a nearly flat, smooth surface of wood or metal hinged at its forward edge to the sternpost. It operates on the principle of unequal water pressures. When the rudder is turned so that one side is more exposed to the force of the water flowing past it than the other side, the stern will be thrust away from the side that the rudder is on and the boat will swerve from its original course. In small craft the rudder is operated manually by a handle termed a tiller or helm. In larger vessels, the rudder is turned by hydraulic, steam, or electrical machinery.
The earliest type of rudder was a paddle or oar used to pry or row the stern of the craft around. The next development was to fasten a steering oar, in a semivertical position, to the vessel’s side near the stern. This arrangement was improved by increasing the width of the blade and attaching a tiller to the upper part of the handle. Ancient Greek and Roman vessels frequently used two sets of these steering paddles. Rudders fastened to the vessel’s sternpost did not come into general use until after the time of William the Conqueror. In ships having two or more screw propellers, rudders are fitted sometimes directly behind each screw.
Special types of rudders use various shapes to obtain greater effectiveness in manoeuvring. The balanced rudder and the semibalanced rudder (see illustration) are shaped so that the force of the water flowing by the rudder will be balanced or partially balanced on either side of its turning axis, thus easing the pressure on the steering mechanism or the helmsman. The lifting rudder is designed with a curvature along its lower edge that will lift the rudder out of danger should it strike an object or the bottom.
Details
A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, airship, or other vehicle that moves through a fluid medium (usually air or water). On an airplane, the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane. A rudder operates by redirecting the fluid past the hull or fuselage, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, tail, or afterend. Often rudders are shaped to minimize hydrodynamic or aerodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be turned by a helmsman. In larger vessels, cables, pushrods, or hydraulics may link rudders to steering wheels. In typical aircraft, the rudder is operated by pedals via mechanical linkages or hydraulics.
Boat rudders details
Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post that comes up through the hull to deck level, often into a math. Inboard keel hung rudders (which are a continuation of the aft trailing edge of the full keel) are traditionally deemed the most damage resistant rudders for off shore sailing. Better performance with faster handling characteristics can be provided by skeg hung rudders on boats with smaller fin keels.
Rudder post and mast placement defines the difference between a ketch and a yawl, as these two-masted vessels are similar. Yawls are defined as having the mizzen mast abaft (i.e. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post.
Small boat rudders that can be steered more or less perpendicular to the hull's longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels. Transom hung rudders or far aft mounted fin rudders generate greater moment and faster turning than more forward mounted keel hung rudders. Rudders on smaller craft can be operated by means of a tiller that fits into the rudder stock that also forms the fixings to the rudder foil. Craft where the length of the tiller could impede movement of the helm can be split with a rubber universal joint and the part adjoined the tiller termed a tiller extension. Tillers can further be extended by means of adjustable telescopic twist locking extension.
There is also the barrel type rudder, where the ship's screw is enclosed and can be swiveled to steer the vessel. Designers claim that this type of rudder on a smaller vessel will answer the helm faster.
Rudder control
Large ships (over 10,000 ton gross tonnage) have requirements on rudder turnover time. To comply with this, high torque rudder controls are employed. One commonly used system is the ram type steering gear. It employs four hydraulic rams to rotate the rudder stock (rotation axis), in turn rotating the rudder.
Aircraft rudders
On an aircraft, a rudder is one of three directional control surfaces, along with the rudder-like elevator (usually attached to the horizontal tail structure, if not a slab elevator) and ailerons (attached to the wings), which control pitch and roll, respectively. The rudder is usually attached to the fin (or vertical stabilizer), which allows the pilot to control yaw about the vertical axis, i.e., change the horizontal direction in which the nose is pointing.
Unlike a ship, both aileron and rudder controls are used together to turn an aircraft, with the ailerons imparting roll and the rudder imparting yaw and also compensating for a phenomenon called adverse yaw. A rudder alone will turn a conventional fixed-wing aircraft, but much more slowly than if ailerons are also used in conjunction. Sometimes pilots may intentionally operate the rudder and ailerons in opposite directions in a maneuver called a slip or sideslip. This may be done to overcome crosswinds and keep the fuselage in line with the runway, or to lose altitude by increasing drag, or both.
Another technique for yaw control, used on some tailless aircraft and flying wings, is to add one or more drag-creating surfaces, such as split ailerons, on the outer wing section. Operating one of these surfaces creates drag on the wing, causing the plane to yaw in that direction. These surfaces are often referred to as drag rudders.
Rudders are typically controlled with pedals.
Additional Information:
Description
The rudder is a primary flight control surface which controls rotation about the vertical axis of an aircraft. This movement is referred to as "yaw". The rudder is a movable surface that is mounted on the trailing edge of the vertical stabilizer or fin. Unlike a boat, the rudder is not used to steer the aircraft; rather, it is used to overcome adverse yaw induced by turning or, in the case of a multi-engine aircraft, by engine failure and also allows the aircraft to be intentionally slipped when required.
Function
In most aircraft, the rudder is controlled through the flight deck rudder pedals which are linked mechanically to the rudder. Deflection of a rudder pedal causes a corresponding rudder deflection in the same direction; that is, pushing the left rudder pedal will result in a rudder deflection to the left. This, in turn, causes the rotation about the vertical axis moving the aircraft nose to the left. In large or high speed aircraft, hydraulic actuators are often used to help overcome mechanical and aerodynamic loads on the rudder surface.
Rudder effectiveness increases with aircraft speed. Thus, at slow speed, large rudder input may be required to achieve the desired results. Smaller rudder movement is required at higher speeds and, in many more sophisticated aircraft, rudder travel is automatically limited when the aircraft is flown above Manoeuvring Speed to prevent deflection angles that could potentially result in structural damage to the aircraft.
#18 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2025-11-08 18:25:52
2388) Alfred Kastler
Gist:
Work
Electrons in atoms and molecules have fixed energy levels, according to the principles of quantum physics. When there are transitions among different energy levels, light with certain frequencies is emitted or absorbed. In 1950 Alfred Kastler presented the idea that electrons, with the help of light or other electromagnetic radiation, can be pumped up to fixed higher energy levels and then fall back to fixed lower levels. This made precise determination of energy levels possible and also was of fundamental importance for development of the laser.
Summary
Alfred Kastler (born May 3, 1902, Guebwiller, Ger. [now in France]—died Jan. 7, 1984, Bandol, France) was a French physicist who won the Nobel Prize for Physics in 1966 for his discovery and development of methods for observing Hertzian resonances within atoms.
In 1920 Kastler went to Paris to study at the École Normale Supérieure. After serving on the science faculties at Bordeaux and Clermont-Ferrand in France and Leuven (Louvain) in Belgium, he returned to the École Normale Supérieure to teach (1941–68). He was professor and codirector of the laboratory of physics there at the time of the Nobel award. During his long and fruitful teaching career he trained an entire generation of French physicists. From 1968 until his retirement in 1972, Kastler served as director of research at the National Centre of Scientific Research. He was active in peace movements and in groups opposed to nuclear proliferation.
Kastler’s Nobel Prize-winning research facilitated the study of atomic structures by means of the radiations that atoms emit under excitation by light and radio waves. His method of stimulating atoms in a particular substance so that they attain higher energy states was called “optical pumping.” Since the light energy used to stimulate the atoms was reemitted, optical pumping marked an important step toward the development of the maser and the laser.
Details
Alfred Kastler (3 May 1902 – 7 January 1984) was a German-born French physicist and Nobel laureate in Physics. He is known for the development of optical pumping.
Biography
Kastler was born in Guebwiller (Alsace, at the time part of the German Empire), and became a French citizen when Alsace reverted to France at the end of World War I. He attended the Lycée Bartholdi in Colmar, Alsace, and then École Normale Supérieure in Paris in 1921. After his studies, he began teaching physics at the Lycée of Mulhouse in 1926, and then taught at the University of Bordeaux, where he was a university professor until 1941. Georges Bruhat asked him to come back to the École Normale Supérieure, where he finally obtained a chair in 1952.
Collaborating with Jean Brossel, he researched quantum mechanics, the interaction between light and atoms, and spectroscopy. Kastler, working on combination of optical resonance and magnetic resonance, developed the technique of "optical pumping". Those works led to the completion of the theory of lasers and masers.
In 1962, he received the first C.E.K Mees Medal from the Optical Society of America, and he was elected an Honorary member of the Society. The following year, he was elected a Fellow.
He won the Nobel Prize in Physics in 1966 "for the discovery and development of optical methods for studying Hertzian resonances in atoms".
He was president of the board of the Institut d'optique théorique et appliquée and served as the first chairman of the non-governmental organization (NGO) Action Against Hunger.
Kastler also wrote poetry (in German). In 1971 he published Europe, ma patrie: Deutsche Lieder eines französischen Europäers (i.e. Europe, my fatherland: German songs of a French European).
In 1976, Kastler was elected to the American Philosophical Society.
In 1978 he became foreign member of the Royal Netherlands Academy of Arts and Sciences.
In 1979, Kastler was awarded the Wilhelm Exner Medal.
Laboratoire Kastler-Brossel
Professor Kastler spent most of his research career at the Ecole Normale Supérieure in Paris where he started after the war a small research group on spectroscopy with his student, Jean Brossel.
Over the forty years that followed, this group trained many young physicists, including Nobel laureates Claude Cohen Tannoudji and Serge Haroche, and had a significant impact on the development of atomic physics in France. The Laboratoire de Spectroscopie hertzienne was renamed Laboratoire Kastler-Brossel in 1994. It has part of its laboratories in Université Pierre et Marie Curie but mainly at the École Normale Supérieure.
Global policy
He was one of the signatories of the agreement to convene a convention for drafting a world constitution. As a result, for the first time in human history, a World Constituent Assembly convened to draft and adopt the Constitution for the Federation of Earth.
Personal life
In December 1924, Kessler married Elise Cosset, a teacher. They had three children, Daniel, Claude-Yves, and Mireille. His sons became teachers, and Mireille became a doctor.
Death
Professor Kastler died on 7 January 1984, in Bandol, France.
(Optical pumping is a process in which light is used to raise (or "pump") electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction to pump the active laser medium so as to achieve population inversion. The technique was developed by the 1966 Nobel Prize winner Alfred Kastler in the early 1950s.)
#19 Re: This is Cool » Miscellany » 2025-11-08 16:50:09
2440) Acetophenone
Gist
Acetophenone (C8H8O) is the simplest aromatic ketone, a colorless liquid with a sweet, cherry-like odor used as a fragrance, solvent, and food additive. It is a reactive organic compound found naturally in foods like apples and cherries and is used to synthesize other products.
Acetophenone is used in the perfume industry for its floral, almond-like scent and as a flavoring agent in foods and tobacco. It also functions as a solvent for plastics and resins, a catalyst in some polymerizations, and an intermediate in the synthesis of pharmaceuticals, resins, and other chemicals. It is used in laboratory settings to demonstrate chemical reactions.
Summary
Acetophenone (C6H5COCH3) is an organic compound used as an ingredient in perfumes and as a chemical intermediate in the manufacture of pharmaceuticals, resins, flavouring agents, and a form of tear gas. It also has been used as a drug to induce sleep.
The compound can be synthesized from benzene and acetyl chloride, but it is prepared commercially by the air oxidation of ethylbenzene.
Pure acetophenone is a colourless liquid, with a melting point of 20.2 °C (68.4 °F) and a boiling point of 202.4 °C (396.3 °F). It is only slightly soluble in water but is freely soluble in ethanol (ethyl alcohol), diethyl ether, and chloroform.
Details
Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances.
Production
Acetophenone is formed as a byproduct of the cumene process, the industrial route for the synthesis of phenol and acetone. In the Hock rearrangement of isopropylbenzene hydroperoxide, migration of a methyl group rather than the phenyl group gives acetophenone and methanol as a result of an alternate rearrangement of the intermediate:
C6H5C(CH3)2O2H → C6H5C(O)CH3 + CH3OH
The cumene process is conducted on such a large scale that even the small amount of acetophenone by-product can be recovered in commercially useful quantities.
Acetophenone is also generated from ethylbenzene hydroperoxide. Ethylbenzene hydroperoxide is primarily converted to 1-phenylethanol (α-methylbenzyl alcohol) in the process with a small amount of by-product acetophenone. Acetophenone is recovered or hydrogenated to 1-phenylethanol which is then dehydrated to produce styrene.
Uses:
Precursor to resins
Commercially significant resins are produced from treatment of acetophenone with formaldehyde and a base. The resulting copolymers are conventionally described with the formula [(C6H5COCH)x(CH2)x]n, resulting from aldol condensation. These substances are components of coatings and inks. Modified acetophenone-formaldehyde resins are produced by the hydrogenation of the aforementioned ketone-containing resins. The resulting polyol can be further crosslinked with diisocyanates. The modified resins are found in coatings, inks and adhesives.
Niche uses
Acetophenone is an ingredient in fragrances that resemble almond, cherry, honeysuckle, jasmine, and strawberry. It is used in chewing gum. It is also listed as an approved excipient by the U.S. FDA.
Laboratory reagent
In instructional laboratories, acetophenone is converted to styrene in a two-step process that illustrates the reduction of carbonyls using sodium borohydride and the dehydration of alcohols:
4 C6H5C(O)CH3 + NaBH4 + 4 H2O → 4 C6H5CH(OH)CH3 + NaOH + B(OH)3
C6H5CH(OH)CH3 → C6H5CH=CH2 + H2O
A similar two-step process is used industrially, but reduction step is performed by hydrogenation over a copper chromite catalyst:
C6H5C(O)CH3 + H2 → C6H5CH(OH)CH3
Being prochiral, acetophenone is also a popular test substrate for asymmetric hydrogenation experiments.
Drugs
Acetophenone is used for the synthesis of many pharmaceuticals.
Natural occurrence
Acetophenone occurs naturally in many foods including apple, cheese, apricot, banana, beef, and cauliflower. It is also a component of castoreum, the exudate from the castor sacs of the mature beaver.
#20 Dark Discussions at Cafe Infinity » Coexist Quotes » 2025-11-08 16:12:42
- Jai Ganesh
- Replies: 0
Coexist Quotes
1. In economics, hope and faith coexist with great scientific pretension and also a deep desire for respectability. - John Kenneth Galbraith
2. As long as we have decided to coexist in peace, we must do so on a firm basis that will withstand time and for generations. - Yasser Arafat
3. My team and I have reunited two elements that coexist with difficulty: respect and affection, because when they love you they don't respect you and when they respect you they don't love you. - Shakira
4. Parliamentary obstructionism should be avoided. It is a weapon to be used in the rarest of the rare cases. Parliamentary accountability is as important as parliamentary debate. Both must coexist. - Arun Jaitley
5. I think the world consists of yin and yang. There should be a balance, and it's important to coexist peacefully, with respect and dignity, and whenever those lines are crossed I think it's important for people to speak up for what they believe in. - Zeenat Aman.
#21 Re: Jai Ganesh's Puzzles » General Quiz » 2025-11-08 15:56:07
Hi,
#10655. What does the term in Geography Circle of latitude mean?
#10656. What does the term in Geography Cirque mean?
#22 Re: Jai Ganesh's Puzzles » English language puzzles » 2025-11-08 15:35:19
Hi,
#5451. What does the noun gâteau mean?
#5452. What does the verb gate-crash mean?
#23 Re: Jai Ganesh's Puzzles » Doc, Doc! » 2025-11-08 14:50:53
Hi,
#2520. What does the medical term Lymphocytopenia mean?
#24 Jokes » Bread Jokes - I » 2025-11-08 14:32:44
- Jai Ganesh
- Replies: 0
Q: What did the bag of flour say to the loaf of bread?
A: "I saw you yeasterday".
* * *
Q: Why doesn't bread like warm weather?
A: Things get Toasty!
* * *
Q: Why are bread jokes always funny?
A: Because they never get mold!
* * *
Q: What do you see when the Pillsbury Doughboy bends over?
A: Doughnuts!
* * *
Q: What did one slice of bread say to the other slice of bread when he saw some butter and jam on the table?
A: We're toast!
* * *
#25 Re: Jai Ganesh's Puzzles » 10 second questions » 2025-11-08 14:04:46
Hi,
#9799.