Random Articles (Page 4)
Have a deep view into what people are curious about.
π 1593 Transported Soldier Legend
A folk legend holds that in October 1593 a soldier of the Spanish Empire (named Gil PΓ©rez in a 1908 version) was mysteriously transported from Manila in the Philippines to the Plaza Mayor (now the ZΓ³calo) in Mexico City. The soldier's claim to have come from the Philippines was disbelieved by the Mexicans until his account of the assassination of GΓ³mez PΓ©rez DasmariΓ±as was corroborated months later by the passengers of a ship which had crossed the Pacific Ocean with the news. Folklorist Thomas Allibone Janvier in 1908 described the legend as "current among all classes of the population of the City of Mexico". Twentieth-century paranormal investigators giving credence to the story have offered teleportation and alien abduction as explanations.
Discussed on
- "In 1593 a soldier of the Spanish Empire was teleported from Manila to Mexico" | 2024-07-02 | 16 Upvotes 4 Comments
- "1593 Transported Soldier Legend" | 2020-10-27 | 67 Upvotes 8 Comments
π Vanadium redox battery
The vanadium redox battery (VRB), also known as the vanadium flow battery (VFB) or vanadium redox flow battery (VRFB), is a type of rechargeable flow battery that employs vanadium ions in different oxidation states to store chemical potential energy. The vanadium redox battery exploits the ability of vanadium to exist in solution in four different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. For several reasons, including their relative bulkiness, most vanadium batteries are currently used for grid energy storage, i.e., attached to power plants or electrical grids.
The possibility of creating a vanadium flow battery was explored by Pissoort in the 1930s, NASA researchers in the 1970s, and Pellegri and Spaziante in the 1970s, but none of them were successful in demonstrating the technology. The first successful demonstration of the all-vanadium redox flow battery which employed vanadium in a solution of sulfuric acid in each half was by Maria Skyllas-Kazacos at the University of New South Wales in the 1980s. Her design used sulfuric acid electrolytes, and was patented by the University of New South Wales in Australia in 1986.
The main advantages of the vanadium redox battery are that it can offer almost unlimited energy capacity simply by using larger electrolyte storage tanks; it can be left completely discharged for long periods with no ill effects; if the electrolytes are accidentally mixed, the battery suffers no permanent damage; a single state of charge between the two electrolytes avoids the capacity degradation due to a single cell in non-flow batteries; the electrolyte is aqueous and inherently safe and non-flammable; and the generation 3 formulation using a mixed acid solution developed by the Pacific Northwest National Laboratory operates over a wider temperature range allowing for passive cooling. VRFBs can be used at depth of discharge (DOD) around 90% and more, i.e. deeper DODs than solid-state batteries (e.g. lithium-based and sodium-based batteries, which are usually specified with DOD=80%). In addition, VRFBs exhibit very long cycle lives: most producers specify cycle durability in excess of 15,000-20,000 charge/discharge cycles. These values are far beyond the cycle lives of solid-state batteries, which is usually in the order of 4,000-5,000 charge/discharge cycles. Consequently, the levelized cost of energy (LCOE, i.e. the system cost divided by the usable energy, the cycle life, and round-trip efficiency) of present VRFB systems is typically in the order of a few tens of $ cents or β¬ cents, namely much lower than the LCOEs of equivalent solid-state batteries and close to the targets of $0.05 and β¬0.05, stated by the US Department of Energy and the European Commission Strategic Energy Technology (SET) Plan, respectively.
The main disadvantages with vanadium redox technology are a relatively poor energy-to-volume ratio in comparison with standard storage batteries, and the relatively poor round trip efficiency. Furthermore, the aqueous electrolyte makes the battery heavy and therefore only useful for stationary applications. Another disadvantage is the relatively high toxicity of oxides of vanadium (see vanadium Β§Β Safety).
Numerous companies and organizations involved in funding and developing vanadium redox batteries include Avalon Battery, Vionx (formerly Premium Power), UniEnergy Technologies and Ashlawn Energy in the United States; Renewable Energy Dynamics Technology in Ireland; Enerox GmbH (formerly Gildemeister energy storage) in Austria; Cellennium in Thailand; Rongke Power in China; Prudent Energy in China; Sumitomo in Japan; H2, Inc. in South Korea; redT in Britain., Australian Vanadium in Australia, and the now defunct Imergy (formerly Deeya). Lately, also several smaller size vanadium redox flow batteries were brought to market (for residential applications) mainly from StorEn Technologies (USA), Schmid Group, VoltStorage and Volterion (all three from Germany), VisBlue (Denmark) or Pinflow energy storage (Czechia).
Discussed on
- "Vanadium redox battery" | 2018-07-28 | 35 Upvotes 31 Comments
π Min Chiu Li
Min Chiu Li (Chinese: ζζζ±; pinyin: LΗ MΗnqiΓΊ; 1919β1980) was a Chinese-American oncologist and cancer researcher. Li was the first scientist to use chemotherapy to cure widely metastatic, malignant cancer.
Discussed on
- "Min Chiu Li" | 2019-08-26 | 130 Upvotes 8 Comments
π Tifinagh (Tuareg Berber Script)
Tifinagh (Tuareg Berber language: β΅β΄Όβ΅β΅ or β΅β΄Όβ΅β΅β΅, Berber pronunciation:Β [tifinaΙ£]) or Tuareg Tifinagh is an abjad script used to write the Tuareg Berber language by the Tuareg Berbers of the Sahara desert in southern Algeria, northeastern Mali, northern Niger and northern Burkina Faso. Tuareg Tifinagh is descended from the ancient Libyco-Berber alphabet.
Neo-Tifinagh (β΅β΅β΄Όβ΅β΅β΄°β΅) is an alphabet that was created in northern Algeria around the 1980s as a modified version of the traditional Tuareg Tifinagh. Neo-Tifinagh has been used since the 1980s by Algerians and later by Moroccans for the symbolic promotion of the Berber language, while mainly using the Berber Latin alphabet in most publications. Neo-Tifinagh is often simply called "Tifinagh" by non-academics in Berber countries and in the media, thus confusing it with the traditional and distinct "Tuareg Tifinagh" which is the actual "Tifinagh".
There are significant differences between the ancient Libyco-Berber script and the Tuareg Tifinagh script, but also many similarities. Many letters from the ancient Libyco-Berber script do not exist (anymore) in the Tuareg Tifinagh, while other letters evolved into a different pronunciation in the current Tuareg Tifinagh script.
There are also significant differences between the Tuareg Tifinagh script and the newly created Neo-Tifinagh alphabet. Many Tuareg Tifinagh letters are discarded in Neo-Tifinagh, and other ones are modified in form or in pronunciation. The Neo-Tifinagh alphabet also features invented vowels and other letters not found in Tuareg Tifinagh. About half of the letters in the Neo-Tifinagh alphabet were either completely invented (β΅₯,β΄»,β΅,β΅,β΅,β΅,β΅―,β΅,β΅,β΄½,β΅ ,β΄Ώ,β΅,β΅ ), modified in form (β΄°,β΅,β΄Ό,β΅,β΅) or repurposed for a different pronunciation (β΅,β΅‘,β΄΅). All traditional Tuareg Tifinagh letters that consist entirely of dots (β΅,β΅,β΄Ύ,β΅,β΅,β΅) were discarded by the creators of Neo-Tifinagh and were replaced by newly invented ones. Tuareg people in the Sahara desert continue to use these dotted letters as an integral part of their traditional Tuareg Tifinagh script, thus deliberately distinguishing themselves and their writings from the northern Berbers of Morocco and northern Algeria who use the Neo-Tifinagh alphabet or the Berber Latin alphabet in writing the Berber language.
The ancient Libyco-Berber script (or the Libyc script) was used by the ancient northern Berbers known as Libyco-Berbers, also known as Libyc people, Numidians, Afri and Mauretanians who inhabited the northern parts of Morocco, Algeria, Tunisia and Libya as well as the Canary Islands west of Morocco.
From the ancient Libyco-Berber script came the Tifinagh script (Tuareg Tifinagh) through a long evolution. And then from the Tifinagh script was the modern Neo-Tifinagh alphabet created.
The name Tifinagh is stylized as TifinaΙ£ in the Berber Latin alphabet, and in the Neo-Tifinagh alphabet it is written as β΅β΅β΄Όβ΅β΅β΄°β΅, while in the Tuareg people's traditional Tifinagh it's written as β΅β΄Όβ΅β΅β΅ or β΅β΄Όβ΅β΅.
Neo-Tifinagh, which was created in northern Algeria around the 1980s, is a heavily modified version of the traditional Tuareg Tifinagh script. This newly created Neo-Tifinagh script spread from Algeria to Morocco and was rebranded by the Moroccan Royal Institute of the Amazigh Culture (IRCAM) as "Tifinaghe-Ircam" or simply "Tifinaghe", and is used in a small part of Moroccan and some Libyan elementary schools to teach the Berber language to children, as well as in a number of literary publications and some websites and media. In Algeria, most Berber language education programs in elementary schools, high schools and university use the Berber Latin alphabet, while a small number of schools use Neo-Tifinagh, Tuareg Tifinagh in the south, or even the Arabic alphabet.
The word tifinagh is thought by some scholars to be a Berberized feminine plural cognate or adaptation of the Latin word "Punicus", (meaning "Punic" or "Phoenician") through the Berber feminine prefix ti- and Latin Punicus; thus tifinagh could possibly mean "the Phoenician (letters)" or "the Punic letters". Others support an etymology involving the Tuareg verb efnegh, meaning to write. However, the Tuareg verb efnegh is probably derived from the noun "Tifinagh" because all the northern Berbers of Morocco, northern Algeria, Tunisia and northern Libya have a different (and probably older) verb "ari, aru, ara" which means "to write".
π Kelly Criterion
In probability theory and intertemporal portfolio choice, the Kelly criterion (or Kelly strategy or Kelly bet), also known as the scientific gambling method, is a formula for bet sizing that leads almost surely to higher wealth compared to any other strategy in the long run (i.e. approaching the limit as the number of bets goes to infinity). The Kelly bet size is found by maximizing the expected value of the logarithm of wealth, which is equivalent to maximizing the expected geometric growth rate. The Kelly Criterion is to bet a predetermined fraction of assets, and it can seem counterintuitive. It was described by J. L. Kelly Jr, a researcher at Bell Labs, in 1956.
For an even money bet, the Kelly criterion computes the wager size percentage by multiplying the percent chance to win by two, then subtracting one-hundred percent. So, for a bet with a 70% chance to win the optimal wager size is 40% of available funds.
The practical use of the formula has been demonstrated for gambling and the same idea was used to explain diversification in investment management. In the 2000s, Kelly-style analysis became a part of mainstream investment theory and the claim has been made that well-known successful investors including Warren Buffett and Bill Gross use Kelly methods. William Poundstone wrote an extensive popular account of the history of Kelly betting.
Discussed on
- "Kelly Criterion" | 2021-04-16 | 330 Upvotes 194 Comments
π Light Characteristic
A light characteristic is all of the properties that make a particular navigational light identifiable. Graphical and textual descriptions of navigational light sequences and colours are displayed on nautical charts and in Light Lists with the chart symbol for a lighthouse, lightvessel, buoy or sea mark with a light on it. Different lights use different colours, frequencies and light patterns, so mariners can identify which light they are seeing.
Discussed on
- "Light Characteristic" | 2024-02-08 | 60 Upvotes 7 Comments
π Tweel β Airless Wheel
The Tweel (a portmanteau of tire and wheel) is an airless tire design developed by the French tire company Michelin. Its significant advantage over pneumatic tires is that the Tweel does not use a bladder full of compressed air, and therefore cannot burst, leak pressure, or become flat. Instead, the Tweel's hub is connected to the rim via flexible polyurethane spokes which fulfil the shock-absorbing role provided by the compressed air in a traditional tire.
Discussed on
- "Tweel β Airless Wheel" | 2015-02-24 | 40 Upvotes 16 Comments
π Puppy Pregnancy Syndrome
Puppy pregnancy syndrome (PPS) is a psychosomatic illness in humans brought on by mass hysteria.
The syndrome is thought to be localized in villages in several states of India, including West Bengal, Assam, Bihar, Jharkhand, Orissa, and Chhattisgarh, and has been reported by tens of thousands of individuals. It is far more prevalent in areas with little access to education.
People suffering from PPS believe that shortly after being bitten by a dog, puppies are conceived within their abdomen. This is said to be especially likely if the dog is sexually excited at the time of the attack. Victims are said to bark like dogs and have reported being able to see the puppies inside them when looking at water or hear them growling in their abdomen. It is believed that the victims will eventually die β especially men, who will give birth to their puppies through the penis.
Witch doctors offer oral cures, which they claim will dissolve the puppies, allowing them to pass through the digestive system and be excreted "without the knowledge of the patient".
Doctors in India have tried to educate the public about the dangers of believing in this condition. Most sufferers are referred to psychiatric services, but in some instances patients fail to take anti-rabies medication before symptom onset, thinking that they are pregnant with a puppy and that folk medicine will cure them. This misbelief is further compounded by witch doctors who state that their medicine will fail if sufferers seek standard treatment.
Some psychiatrists believe that PPS meets the criteria for a culture-bound disorder.
π Type A and Type B personality theory
Type A and Type B personality hypothesis describes two contrasting personality types. In this hypothesis, personalities that are more competitive, highly organized, ambitious, impatient, highly aware of time management and/or aggressive are labeled Type A, while more relaxed, less 'neurotic', 'frantic', 'explainable', personalities are labeled Type B.
The two cardiologists who developed this theory came to believe that Type A personalities had a greater chance of developing coronary heart disease. Following the results of further studies and considerable controversy about the role of the tobacco industry funding of early research in this area, some reject, either partially or completely, the link between Type A personality and coronary disease. Nevertheless, this research had a significant effect on the development of the health psychology field, in which psychologists look at how an individual's mental state affects physical health.
Discussed on
- "Type A and Type B personality theory" | 2014-03-22 | 26 Upvotes 3 Comments
π How a Buffer Overflow Works
In information security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.
Buffers are areas of memory set aside to hold data, often while moving it from one section of a program to another, or between programs. Buffer overflows can often be triggered by malformed inputs; if one assumes all inputs will be smaller than a certain size and the buffer is created to be that size, then an anomalous transaction that produces more data could cause it to write past the end of the buffer. If this overwrites adjacent data or executable code, this may result in erratic program behavior, including memory access errors, incorrect results, and crashes.
Exploiting the behavior of a buffer overflow is a well-known security exploit. On many systems, the memory layout of a program, or the system as a whole, is well defined. By sending in data designed to cause a buffer overflow, it is possible to write into areas known to hold executable code and replace it with malicious code, or to selectively overwrite data pertaining to the program's state, therefore causing behavior that was not intended by the original programmer. Buffers are widespread in operating system (OS) code, so it is possible to make attacks that perform privilege escalation and gain unlimited access to the computer's resources. The famed Morris worm in 1988 used this as one of its attack techniques.
Programming languages commonly associated with buffer overflows include C and C++, which provide no built-in protection against accessing or overwriting data in any part of memory and do not automatically check that data written to an array (the built-in buffer type) is within the boundaries of that array. Bounds checking can prevent buffer overflows, but requires additional code and processing time. Modern operating systems use a variety of techniques to combat malicious buffer overflows, notably by randomizing the layout of memory, or deliberately leaving space between buffers and looking for actions that write into those areas ("canaries").
Discussed on
- "How a Buffer Overflow Works" | 2009-04-01 | 17 Upvotes 6 Comments