Have a deep view into what people are curious about.

🔗 Biography 🔗 Australia 🔗 Crime 🔗 Death 🔗 Australia/Australian crime 🔗 Australia/Adelaide

The Somerton Man was an unidentified man whose body was found on 1 December 1948 on the beach at Somerton Park, a suburb of Adelaide, South Australia. The case is also known after the Persian phrase tamám shud (Persian: تمام شد), meaning "is over" or "is finished", which was printed on a scrap of paper found months later in the fob pocket of the man's trousers. The scrap had been torn from the final page of a copy of Rubaiyat of Omar Khayyám, authored by 12th-century poet Omar Khayyám.

Following a public appeal by police, the book from which the page had been torn was located. On the inside back cover, detectives read through indentations left from previous handwriting: a local telephone number, another unidentified number, and text that resembled a coded message. The text has not been deciphered or interpreted in a way that satisfies authorities on the case.

Since the early stages of the police investigation, the case has been considered "one of Australia's most profound mysteries". There has been intense speculation ever since regarding the identity of the victim, the cause of his death, and the events leading up to it. Public interest in the case remains significant for several reasons: the death occurred at a time of heightened international tensions following the beginning of the Cold War; the apparent involvement of a secret code; the possible use of an undetectable poison; and the inability of authorities to identify the dead man.

On 26 July 2022, Adelaide University professor Derek Abbott, in association with genealogist Colleen M. Fitzpatrick, claimed to have identified the man as Carl "Charles" Webb, an electrical engineer and instrument maker born in 1905, based on genetic genealogy from DNA of the man's hair. South Australia Police and Forensic Science South Australia have not verified the result, but South Australia Police said they were "cautiously optimistic" about it.

🔗 Medicine 🔗 Medicine/Neurology

Type 3 diabetes is a proposed term to describe the interlinked association between type 1 and type 2 diabetes, and Alzheimer's disease. This term is used to look into potential triggers of Alzheimer's disease in people with diabetes.

The proposed progression from diabetes to Alzheimer's disease is inadequately understood; however there are a number of hypotheses describing potential links between the two diseases. The internal mechanism of Insulin resistance and other metabolic risk factors such as hyperglycaemia, caused by oxidative stress and lipid peroxidation are common processes thought to be contributors to the development of Alzheimer's disease in diabetics.

Diagnosis for this disease is different between patients with type 1 and type 2 diabetes. Type 1 diabetes is usually discovered in children and adolescence while type 2 diabetic patients are often diagnosed later in life. While Type 3 diabetes is not a diagnosis in itself, a diagnosis of suspected Alzheimer's disease can be established through observational signs and sometimes with neuroimaging techniques such as Magnetic Resonance Imaging (MRI) to observe abnormalities in diabetic patient's brain tissue.

The techniques used to prevent the disease in patients with diabetes are similar to individuals who do not show signs of the disease. The four pillars of Alzheimer's disease prevention is currently used as a guide for individuals of whom are at risk of developing Alzheimer's disease.

Research into the effectiveness of Glucagon-like Peptide 1 and Melatonin administration to manage the progression of Alzheimer's disease in diabetic patients is currently being conducted to decrease the rate at which Alzheimer's disease progresses.

Labelling Alzheimer's disease as Type 3 Diabetes is generally controversial, and this definition is not a known medical diagnosis. While insulin resistance is a risk factor for the development of Alzheimer's disease and some other dementias, causes of Alzheimer's disease are likely to be much more complex than being explained by insulin factors on their own, and indeed several patients with Alzheimer's disease have normal insulin metabolism.

🔗 Mathematics 🔗 Biology 🔗 Physics 🔗 Plants

Tendril perversion, often referred to in context as simply perversion, is a geometric phenomenon found in helical structures such as plant tendrils, in which a helical structure forms that is divided into two sections of opposite chirality, with a transition between the two in the middle. A similar phenomenon can often be observed in kinked helical cables such as telephone handset cords.

The phenomenon was known to Charles Darwin, who wrote in 1865,

A tendril ... invariably becomes twisted in one part in one direction, and in another part in the opposite direction... This curious and symmetrical structure has been noticed by several botanists, but has not been sufficiently explained.

The term "tendril perversion" was coined by Goriely and Tabor in 1998 based on the word perversion found in the 19th Century science literature. "Perversion" is a transition from one chirality to another and was known to James Clerk Maxwell, who attributed it to the topologist J. B. Listing.

Tendril perversion can be viewed as an example of spontaneous symmetry breaking, in which the strained structure of the tendril adopts a configuration of minimum energy while preserving zero overall twist.

Tendril perversion has been studied both experimentally and theoretically. Gerbode et al. have made experimental studies of the coiling of cucumber tendrils. A detailed study of a simple model of the physics of tendril perversion was made by MacMillen and Goriely in the early 2000s. Liu et al. showed in 2014 that "the transition from a helical to a hemihelical shape, as well as the number of perversions, depends on the height to width ratio of the strip's cross-section."

Generalized tendril perversions were put forward by Silva et al., to include perversions that can be intrinsically produced in elastic filaments, leading to a multiplicity of geometries and dynamical properties.

🔗 Trains

The symmetry minute is a significant time point in the clock face timetables used by many public transport operators. At this point in the cycle, a train in a clock-face timetable meets its counterpart travelling in the opposite direction on the same line. If this crossing time is constant across a network, connecting times between lines are kept consistent in both directions.

At the symmetry time, the timetable is mirrored in both directions. At the ends of the line, the center of the turnaround time coincides with the symmetry minute. The distance between two consecutive symmetry times is equal to half the cycle time, so on an hourly schedule, opposite trains on the same line cross every 30 minutes. On a two-hour cycle, there is a symmetry time every hour.

In principle, a train-encounter can be set at any time. However, at the transition between two networks or lines, it is expedient to set uniform symmetry minutes, to create a symmetrical connection relation. For the long-distance cycle systems of ÖBB and SBB, the Forschungsgesellschaft für Straßen- und Verkehrswesen für Deutschland (Research Association for Roads and Traffic for Germany) recommends minute 58, so a four-minute minimum connecting time results in a departure at minute 0. Meanwhile, most railways in Central Europe and a number of other transport operators have established the symmetry minute 58½, for a three-minute hold time before a departure at minute 0. Shorter cycles have additional symmetry minutes, shifted by half the cycle time. So an hourly cycle has symmetries at minutes 28½ and 58½, a 30-minute cycle has symmetries at minutes 13½, 28½, 43½ and 58½, and so on.

The following table shows the departure times in opposite directions for an hourly cycle, using the 58½ symmetry minute (the most common in Central Europe). The other departure times for shorter cycles can be calculated from it. The last line gives the meeting times.

🔗 Statistics

In statistics, a Pólya urn model (also known as a Pólya urn scheme or simply as Pólya's urn), named after George Pólya, is a type of statistical model used as an idealized mental exercise framework, unifying many treatments.

In an urn model, objects of real interest (such as atoms, people, cars, etc.) are represented as colored balls in an urn or other container. In the basic Pólya urn model, the urn contains x white and y black balls; one ball is drawn randomly from the urn and its color observed; it is then returned in the urn, and an additional ball of the same color is added to the urn, and the selection process is repeated. Questions of interest are the evolution of the urn population and the sequence of colors of the balls drawn out.

This endows the urn with a self-reinforcing property sometimes expressed as the rich get richer.

Note that in some sense, the Pólya urn model is the "opposite" of the model of sampling without replacement, where every time a particular value is observed, it is less likely to be observed again, whereas in a Pólya urn model, an observed value is more likely to be observed again. In both of these models, the act of measurement has an effect on the outcome of future measurements. (For comparison, when sampling with replacement, observation of a particular value has no effect on how likely it is to observe that value again.) In a Pólya urn model, successive acts of measurement over time have less and less effect on future measurements, whereas in sampling without replacement, the opposite is true: After a certain number of measurements of a particular value, that value will never be seen again.

One of the reasons for interest in this particular rather elaborate urn model (i.e. with duplication and then replacement of each ball drawn) is that it provides an example in which the count (initially x black and y white) of balls in the urn is not concealed, which is able to approximate the correct updating of subjective probabilities appropriate to a different case in which the original urn content is concealed while ordinary sampling with replacement is conducted (without the Pólya ball-duplication). Because of the simple "sampling with replacement" scheme in this second case, the urn content is now static, but this greater simplicity is compensated for by the assumption that the urn content is now unknown to an observer. A Bayesian analysis of the observer's uncertainty about the urn's initial content can be made, using a particular choice of (conjugate) prior distribution. Specifically, suppose that an observer knows that the urn contains only identical balls, each coloured either black or white, but he does not know the absolute number of balls present, nor the proportion that are of each colour. Suppose that he holds prior beliefs about these unknowns: for him the probability distribution of the urn content is well approximated by some prior distribution for the total number of balls in the urn, and a beta prior distribution with parameters (x,y) for the initial proportion of these which are black, this proportion being (for him) considered approximately independent of the total number. Then the process of outcomes of a succession of draws from the urn (with replacement but without the duplication) has approximately the same probability law as does the above Pólya scheme in which the actual urn content was not hidden from him. The approximation error here relates to the fact that an urn containing a known finite number m of balls of course cannot have an exactly beta-distributed unknown proportion of black balls, since the domain of possible values for that proportion are confined to being multiples of ${\displaystyle 1/m}$, rather than having the full freedom to assume any value in the continuous unit interval, as would an exactly beta distributed proportion. This slightly informal account is provided for reason of motivation, and can be made more mathematically precise.

This basic Pólya urn model has been enriched and generalized in many ways.

🔗 Medicine 🔗 Pharmacology

Sofosbuvir, sold under the brand name Sovaldi among others, is a medication used to treat hepatitis C. It is only recommended with some combination of ribavirin, peginterferon-alfa, simeprevir, ledipasvir, daclatasvir, or velpatasvir. Cure rates are 30 to 97% depending on the type of hepatitis C virus involved. Safety during pregnancy is unclear; some of the medications used in combination may result in harm to the baby. It is taken by mouth.

Common side effects include feeling tired, headache, nausea, and trouble sleeping. Side effects are generally more common in interferon-containing regimens. Sofosbuvir may reactivate hepatitis B in those who have been previously infected. In combination with ledipasvir, daclatasvir or simeprevir it is not recommended with amiodarone due to the risk of an abnormally slow heartbeat. Sofosbuvir is in the nucleotide analog family of medication and works by blocking the hepatitis C NS5B protein.

Sofosbuvir was discovered in 2007, and approved for medical use in the United States in 2013. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. As of 2016, a 12-week course of treatment costs about US$84,000 in the United States, US$53,000 in the United Kingdom, US$45,000 in Canada, and about US$500 in India. Over 60,000 people were treated with sofosbuvir in its first 30 weeks being sold in the United States.

🔗 Physics 🔗 New York (state) 🔗 National Register of Historic Places 🔗 New York (state)/Long Island

Wardenclyffe Tower (1901–1917), also known as the Tesla Tower, was an early experimental wireless transmission station designed and built by Nikola Tesla in Shoreham, New York in 1901–1902. Tesla intended to transmit messages, telephony and even facsimile images across the Atlantic to England and to ships at sea based on his theories of using the Earth to conduct the signals. His decision to scale up the facility and add his ideas of wireless power transmission to better compete with Guglielmo Marconi's radio based telegraph system was met with refusal to fund the changes by the project's primary backer, financier J. P. Morgan. Additional investment could not be found, and the project was abandoned in 1906, never to become operational.

In an attempt to satisfy Tesla's debts, the tower was demolished for scrap in 1917 and the property taken in foreclosure in 1922. For 50 years, Wardenclyffe was a processing facility producing photography supplies. Many buildings were added to the site and the land it occupies has been trimmed down to 16 acres (6.5 ha) but the original, 94 by 94 ft (29 by 29 m), brick building designed by Stanford White remains standing to this day.

In the 1980s and 2000s, hazardous waste from the photographic era was cleaned up, and the site was sold and cleared for new development. A grassroots campaign to save the site succeeded in purchasing the property in 2013, with plans to build a future museum dedicated to Nikola Tesla. In 2018 the property was listed on the National Register of Historic Places.

🔗 Mathematics 🔗 Game theory

The angel problem is a question in combinatorial game theory proposed by John Horton Conway. The game is commonly referred to as the Angels and Devils game. The game is played by two players called the angel and the devil. It is played on an infinite chessboard (or equivalently the points of a 2D lattice). The angel has a power k (a natural number 1 or higher), specified before the game starts. The board starts empty with the angel at the origin. On each turn, the angel jumps to a different empty square which could be reached by at most k moves of a chess king, i.e. the distance from the starting square is at most k in the infinity norm. The devil, on its turn, may add a block on any single square not containing the angel. The angel may leap over blocked squares, but cannot land on them. The devil wins if the angel is unable to move. The angel wins by surviving indefinitely.

The angel problem is: can an angel with high enough power win?

There must exist a winning strategy for one of the players. If the devil can force a win then it can do so in a finite number of moves. If the devil cannot force a win then there is always an action that the angel can take to avoid losing and a winning strategy for it is always to pick such a move. More abstractly, the "pay-off set" (i.e., the set of all plays in which the angel wins) is a closed set (in the natural topology on the set of all plays), and it is known that such games are determined. Of course, for any infinite game, if player 2 doesn't have a winning strategy, player 1 can always pick a move that leads to a position where player 2 doesn't have a winning strategy, but in some games, simply playing forever doesn't confer a win to player 1, and that's why undetermined games may exist.

Conway offered a reward for a general solution to this problem ($100 for a winning strategy for an angel of sufficiently high power, and $1000 for a proof that the devil can win irrespective of the angel's power). Progress was made first in higher dimensions. In late 2006, the original problem was solved when independent proofs appeared, showing that an angel can win. Bowditch proved that a 4-angel (that is, an angel with power k=4) can win and Máthé and Kloster gave proofs that a 2-angel can win. At this stage, it has not been confirmed by Conway who is to be the recipient of his prize offer, or whether each published and subsequent solution will also earn $100 US.

🔗 Chemicals 🔗 Occupational Safety and Health 🔗 Food and drink 🔗 Rocks and minerals 🔗 Chemicals/Chemicals worklist

Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. Powdered borax is white, consisting of soft colorless crystals that dissolve in water. A number of closely related minerals or chemical compounds that differ in their crystal water content are referred to as borax, and the word is usually used to refer to the octahydrate. Commercially sold borax is partially dehydrated.

Borax is a component of many detergents, cosmetics, and enamel glazes. It is used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound, in the manufacture of fiberglass, as a flux in metallurgy, neutron-capture shields for radioactive sources, a texturing agent in cooking, as a cross-linking agent in Slime, as an alkali in photographic developers, as a precursor for other boron compounds, and along with its inverse, boric acid, is useful as an insecticide.

In artisanal gold mining, borax is sometimes used as part of a process (as a flux) meant to eliminate the need for toxic mercury in the gold extraction process, although it cannot directly replace mercury. Borax was reportedly used by gold miners in parts of the Philippines in the 1900s.

Borax was first discovered in dry lake beds in Tibet and was imported via the Silk Road to the Arabian Peninsula in the 8th century AD. Borax first came into common use in the late 19th century when Francis Marion Smith's Pacific Coast Borax Company began to market and popularize a large variety of applications under the 20 Mule Team Borax trademark, named for the method by which borax was originally hauled out of the California and Nevada deserts.