Have a deep view into what people are curious about.

🔗 Law Enforcement 🔗 Chicago

A police riot is a riot carried out by the police; a riot that the police are responsible for instigating, escalating or sustaining as a violent confrontation; an event characterized by widespread police brutality; a mass police action that is violently undertaken against civilians for the purpose of political repression. The term "police riot" was popularized after its use in the Walker Report, which investigated the events surrounding the 1968 Democratic National Convention in Chicago to describe the "unrestrained and indiscriminate" violence that the police "inflicted upon persons who had broken no law, disobeyed no order, made no threat." In this sense a police riot refers to rioting carried out by the police (or those acting in a police capacity) rather than a riot carried out by people who may be motivated to a greater or lesser degree by grievances with the police (see the 1981 Toxteth riots or the 1992 Los Angeles Riots for examples of riots over policing rather than police riots).

🔗 Physics 🔗 Physics/relativity

In theoretical physics, particularly in discussions of gravitation theories, Mach's principle (or Mach's conjecture) is the name given by Einstein to an imprecise hypothesis often credited to the physicist and philosopher Ernst Mach. The hypothesis attempted to explain how rotating objects, such as gyroscopes and spinning celestial bodies, maintain a frame of reference.

The proposition is that the existence of absolute rotation (the distinction of local inertial frames vs. rotating reference frames) is determined by the large-scale distribution of matter, as exemplified by this anecdote:

You are standing in a field looking at the stars. Your arms are resting freely at your side, and you see that the distant stars are not moving. Now start spinning. The stars are whirling around you and your arms are pulled away from your body. Why should your arms be pulled away when the stars are whirling? Why should they be dangling freely when the stars don't move?

Mach's principle says that this is not a coincidence—that there is a physical law that relates the motion of the distant stars to the local inertial frame. If you see all the stars whirling around you, Mach suggests that there is some physical law which would make it so you would feel a centrifugal force. There are a number of rival formulations of the principle, often stated in vague ways like "mass out there influences inertia here". A very general statement of Mach's principle is "local physical laws are determined by the large-scale structure of the universe".

Mach's concept was a guiding factor in Einstein's development of the general theory of relativity. Einstein realized that the overall distribution of matter would determine the metric tensor which indicates which frame is stationary with respect to rotation. Frame-dragging and conservation of gravitational angular momentum makes this into a true statement in the general theory in certain solutions. But because the principle is so vague, many distinct statements have been made which would qualify as a Mach principle, and some of which are false. The Gödel rotating universe is a solution of the field equations that is designed to disobey Mach's principle in the worst possible way. In this example, the distant stars seem to be revolving faster and faster as one moves further away. This example does not completely settle the question of the physical relevance of the principle because it has closed timelike curves.

🔗 Physics 🔗 Astronomy

A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars (between 0.8 solar masses (M_☉) and 2.0 M_☉) during their red giant phase. The Sun is predicted to experience a flash 1.2 billion years after it leaves the main sequence. A much rarer runaway helium fusion process can also occur on the surface of accreting white dwarf stars.

Low-mass stars do not produce enough gravitational pressure to initiate normal helium fusion. As the hydrogen in the core is exhausted, some of the helium left behind is instead compacted into degenerate matter, supported against gravitational collapse by quantum mechanical pressure rather than thermal pressure. Subsequent hydrogen shell fusion further increases the mass of the core until it reaches temperature of approximately 100 million kelvin, which is hot enough to initiate helium fusion (or "helium burning") in the core.

However, a fundamental quality of degenerate matter is that increases in temperature do not produce an increase in the pressure of the matter until the thermal pressure becomes so very high that it exceeds degeneracy pressure. In main sequence stars, thermal expansion regulates the core temperature, but in degenerate cores, this does not occur. Helium fusion increases the temperature, which increases the fusion rate, which further increases the temperature in a runaway reaction which quickly spans the entire core. This produces a flash of very intense helium fusion that lasts only a few minutes, but during that time, produces energy at a rate comparable to the entire Milky Way galaxy.

In the case of normal low-mass stars, the vast energy release causes much of the core to come out of degeneracy, allowing it to thermally expand. This consumes most of the total energy released by the helium flash, and any left-over energy is absorbed into the star's upper layers. Thus the helium flash is mostly undetectable by observation, and is described solely by astrophysical models. After the core's expansion and cooling, the star's surface rapidly cools and contracts in as little as 10,000 years until it is roughly 2% of its former radius and luminosity. It is estimated that the electron-degenerate helium core weighs about 40% of the star mass and that 6% of the core is converted into carbon.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory

MOLLE (pronounced , similar in pronunciation to the name Molly) is an acronym for Modular Lightweight Load-carrying Equipment. It is used to define the current generation of load-bearing equipment and backpacks used by a number of NATO armed forces, especially the British Army and the United States Army.

The system's modularity is derived from the use of Pouch Attachment Ladder System (PALS) webbing equipment as rows of heavy-duty nylon stitched onto the vest to allow for the attachment of various compatible pouches and accessories. This method of attachment has become a de facto standard for modular tactical gear, replacing the All-purpose Lightweight Individual Carrying Equipment (ALICE) system used in the earliest modular vest systems (which is still in use with many police forces).

🔗 Statistics

Nelson rules are a method in process control of determining if some measured variable is out of control (unpredictable versus consistent). Rules, for detecting "out-of-control" or non-random conditions were first postulated by Walter A. Shewhart in the 1920s. The Nelson rules were first published in the October 1984 issue of the Journal of Quality Technology in an article by Lloyd S Nelson.

The rules are applied to a control chart on which the magnitude of some variable is plotted against time. The rules are based on the mean value and the standard deviation of the samples.

The above eight rules apply to a chart of a variable value.

A second chart, the moving range chart, can also be used but only with rules 1, 2, 3 and 4. Such a chart plots a graph of the maximum value - minimum value of N adjacent points against the time sample of the range.

An example moving range: if N = 3 and values are 1, 3, 5, 3, 3, 2, 4, 5 then the sets of adjacent points are (1,3,5) (3,5,3) (5,3,3) (3,3,2) (3,2,4) (2,4,5) resulting in moving range values of (5-1) (5-3) (5-3) (3-2) (4-2) (5-2) = 4, 2, 2, 1, 2, 3.

Applying these rules indicates when a potential "out of control" situation has arisen. However, there will always be some false alerts and the more rules applied the more will occur. For some processes, it may be beneficial to omit one or more rules. Equally there may be some missing alerts where some specific "out of control" situation is not detected. Empirically, the detection accuracy is good.

🔗 Brands 🔗 Health and fitness 🔗 AIDS 🔗 U2

Product Red, stylized as (PRODUCT)^RED or (PRODUCT)RED, is a licensed brand by the company Red, stylized as (RED), that seeks to engage the private sector in raising awareness and funds to help eliminate HIV/AIDS in eight African countries, namely Eswatini (formerly Swaziland), Ghana, Kenya, Lesotho, Rwanda, South Africa, Tanzania, and Zambia. It is licensed to partner companies including Apple Inc., Nike, American Express (UK), The Coca-Cola Company, Starbucks, Converse, Electronic Arts, Primark, Head, Buckaroo, Penguin Classics (UK & International), Gap, Armani, FIAT, Hallmark (US), SAP, Beats Electronics, and Supercell. The concept was founded in 2006 by U2 frontman and activist Bono, together with Bobby Shriver of the One Campaign and DATA. The Global Fund to Fight AIDS, Tuberculosis and Malaria is the recipient of Product Red's money.

As part of a new business model, each partner company creates a product with the Product Red logo. In return for the opportunity to increase revenue through the Product Red license, up to 50% of profits gained by each partner is donated to the Global Fund. As Product Red is owned by Red, a portion of the contributions received from the partner brands is assigned as profit. Such an amalgamation of humanitarian aid and for-profit businesses is one example of "ethical consumerism".

In 2012, One Campaign acquired Red as a division of One. Both organizations were co-founded by Bono and Shriver.

Since 2020, Product Red has been used in the global fund to combat the COVID-19 pandemic.

🔗 Astronomy 🔗 Astronomy/Astronomical objects

TON 618 (short for Tonantzintla 618) is a hyperluminous, broad-absorption-line, radio-loud quasar and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40 billion M_☉.

🔗 Germany 🔗 Death 🔗 Crime and Criminal Biography 🔗 Bavaria 🔗 Crime and Criminal Biography/Serial Killer

The Hinterkaifeck murders occurred on the evening of 31 March 1922, when six inhabitants of a small Bavarian farmstead, located approximately 70 kilometres (43 mi) north of Munich, Germany, were murdered by an unknown assailant. The six victims were Andreas Gruber (aged 63), his wife Cäzilia Gruber (aged 72), their widowed daughter Viktoria Gabriel (aged 35), Viktoria's children, Cäzilia (aged 7) and Josef (aged 2), and the maid, Maria Baumgartner (aged 44). They were all found struck dead with a mattock, also known as a "grub axe". The perpetrator(s) lived with the six corpses of their victims for three days. The murders are considered one of the most gruesome and puzzling unsolved crimes in German history.

Four of the dead bodies were found stacked up in the barn, the victims having been lured there, one by one. Prior to the incident, the family and their former maid reported hearing strange noises coming from the attic, which led to that maid leaving. The case remains unsolved to this day.

🔗 Brands 🔗 Time

Atmos is the brand name of a mechanical torsion pendulum clock manufactured by Jaeger-LeCoultre in Switzerland which does not need to be wound manually. It gets the energy it needs to run from temperature and atmospheric pressure changes in the environment, and can run for years without human intervention.

The clock is driven by a mainspring, which is wound by the expansion and contraction of liquid and gaseous ethyl chloride in an internal hermetically sealed bellows. The ethyl chloride vaporises into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spring slackens. This motion constantly winds the mainspring. A temperature variation of only one degree in the range between 15 °C (59 °F) and 30 °C (86 °F), or a pressure variation of 3 mmHg, is sufficient for two days' operation.

In order to run the clock on this small amount of energy, everything inside the Atmos has to work in as friction-free a manner as possible. For timekeeping it uses a torsion pendulum, which consumes less energy than an ordinary pendulum. The torsion pendulum has a period of precisely one minute; thirty seconds to rotate in one direction and thirty seconds to return to the starting position. This is thirty times slower than the 0.994 m (39.1 in) seconds pendulum typically found in a longcase clock, where each swing (or half-period) takes one second.

🔗 Mathematics 🔗 Archaeology

The Ishango bone is a bone tool and possible mathematical object, dated to the Upper Paleolithic era. It is a dark brown length of bone, the fibula of a baboon, with a sharp piece of quartz affixed to one end, perhaps for engraving. It is thought by some to be a tally stick, as it has a series of what has been interpreted as tally marks carved in three columns running the length of the tool, though it has also been suggested that the scratches might have been to create a better grip on the handle or for some other non-mathematical reason. Others argue that the marks on the object are non-random and that it was likely a kind of counting tool and used to perform simple mathematical procedures.