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🔗 Computing 🔗 Computer science 🔗 Mathematics 🔗 Physics 🔗 Statistics

Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo methods are mainly used in three problem classes: optimization, numerical integration, and generating draws from a probability distribution.

In physics-related problems, Monte Carlo methods are useful for simulating systems with many coupled degrees of freedom, such as fluids, disordered materials, strongly coupled solids, and cellular structures (see cellular Potts model, interacting particle systems, McKean–Vlasov processes, kinetic models of gases).

Other examples include modeling phenomena with significant uncertainty in inputs such as the calculation of risk in business and, in mathematics, evaluation of multidimensional definite integrals with complicated boundary conditions. In application to systems engineering problems (space, oil exploration, aircraft design, etc.), Monte Carlo–based predictions of failure, cost overruns and schedule overruns are routinely better than human intuition or alternative "soft" methods.

In principle, Monte Carlo methods can be used to solve any problem having a probabilistic interpretation. By the law of large numbers, integrals described by the expected value of some random variable can be approximated by taking the empirical mean (a.k.a. the sample mean) of independent samples of the variable. When the probability distribution of the variable is parameterized, mathematicians often use a Markov chain Monte Carlo (MCMC) sampler. The central idea is to design a judicious Markov chain model with a prescribed stationary probability distribution. That is, in the limit, the samples being generated by the MCMC method will be samples from the desired (target) distribution. By the ergodic theorem, the stationary distribution is approximated by the empirical measures of the random states of the MCMC sampler.

In other problems, the objective is generating draws from a sequence of probability distributions satisfying a nonlinear evolution equation. These flows of probability distributions can always be interpreted as the distributions of the random states of a Markov process whose transition probabilities depend on the distributions of the current random states (see McKean–Vlasov processes, nonlinear filtering equation). In other instances we are given a flow of probability distributions with an increasing level of sampling complexity (path spaces models with an increasing time horizon, Boltzmann–Gibbs measures associated with decreasing temperature parameters, and many others). These models can also be seen as the evolution of the law of the random states of a nonlinear Markov chain. A natural way to simulate these sophisticated nonlinear Markov processes is to sample multiple copies of the process, replacing in the evolution equation the unknown distributions of the random states by the sampled empirical measures. In contrast with traditional Monte Carlo and MCMC methodologies, these mean-field particle techniques rely on sequential interacting samples. The terminology mean field reflects the fact that each of the samples (a.k.a. particles, individuals, walkers, agents, creatures, or phenotypes) interacts with the empirical measures of the process. When the size of the system tends to infinity, these random empirical measures converge to the deterministic distribution of the random states of the nonlinear Markov chain, so that the statistical interaction between particles vanishes.

Despite its conceptual and algorithmic simplicity, the computational cost associated with a Monte Carlo simulation can be staggeringly high. In general the method requires many samples to get a good approximation, which may incur an arbitrarily large total runtime if the processing time of a single sample is high. Although this is a severe limitation in very complex problems, the embarrassingly parallel nature of the algorithm allows this large cost to be reduced (perhaps to a feasible level) through parallel computing strategies in local processors, clusters, cloud computing, GPU, FPGA, etc.

🔗 Maps

In cartography, a trap street is a fictitious entry in the form of a misrepresented street on a map, often outside the area the map nominally covers, for the purpose of "trapping" potential copyright violators of the map who, if caught, would be unable to explain the inclusion of the "trap street" on their map as innocent. On maps that are not of streets, other "copyright trap" features (such as nonexistent towns, or mountains with the wrong elevations) may be inserted or altered for the same purpose.

Trap streets are often nonexistent streets; but sometimes, rather than actually depicting a street where none exists, a map will misrepresent the nature of a street in a fashion that can still be used to detect copyright violators but is less likely to interfere with navigation. For instance, a map might add nonexistent bends to a street, or depict a major street as a narrow lane, without changing its location or its connections to other streets.

Trap streets are rarely acknowledged by publishers. One known case is a popular driver's atlas for the city of Athens, Greece, which has a warning inside its front cover that potential copyright violators should beware of trap streets.

🔗 California 🔗 California/Los Angeles area

Skid Row is a neighborhood in Downtown Los Angeles. The area is also known as Central City East.

As of a 2019 count, the population of the district was 4,757. Skid Row contains one of the largest stable populations (about 2,783) of homeless people in the United States and has been known for its condensed homeless population since the 1930s. Its long history of police raids, targeted city initiatives, and homelessness advocacy make it one of the most notable districts in Los Angeles.

Covering fifty city blocks (2.71 sq mi) immediately east of downtown Los Angeles, Skid Row is bordered by Third Street to the north, Seventh Street to the south, Alameda Street to the east, and Main Street to the west.

🔗 United States 🔗 Internet 🔗 Law 🔗 Freedom of speech 🔗 Law Enforcement 🔗 United States/FBI

A warrant canary is a method by which a communications service provider aims to inform its users that the provider has been served with a government subpoena despite legal prohibitions on revealing the existence of the subpoena. The warrant canary typically informs users that there has not been a court-issued subpoena as of a particular date. If the canary is not updated for the period specified by the host or if the warning is removed, users are to assume that the host has been served with such a subpoena. The intention is to allow the provider to warn users of the existence of a subpoena passively, without technically violating the court order not to do so.

Some subpoenas, such as those covered under 18 U.S.C. §2709(c) of the USA Patriot Act, provide criminal penalties for disclosing the existence of the subpoena to any third party, including the service provider's users.

National Security Letters (NSL) originated in the 1986 Electronic Communications Privacy Act and originally targeted those suspected of being agents of a foreign power. Targeting agents of a foreign power was revised in 2001 under the Patriot Act to allow NSLs to target those who may have information deemed relevant to both counterintelligence activities directed against the United States and terrorism. The idea of using negative pronouncements to thwart the nondisclosure requirements of court orders and served secret warrants was first proposed by Steven Schear on the cypherpunks mailing list, mainly to uncover targeted individuals at ISPs. It was also suggested for and used by public libraries in 2002 in response to the USA Patriot Act, which could have forced librarians to disclose the circulation history of library patrons.

🔗 Songs

"Hitler Has Only Got One Ball", sometimes known as "The River Kwai March", is a World War II British song, the lyrics of which, sung to the tune of the World War I-era "Colonel Bogey March", impugn the masculinity of Nazi leaders by alleging they had missing, deformed, or undersized testicles. Multiple variant lyrics exist, but the most common version refers to rumours that Adolf Hitler had monorchism ("one ball"), and accuses Hermann Göring and Heinrich Himmler of microorchidism ("two but very small") and Joseph Goebbels of anorchia ("no balls at all"). An alternative version suggests Hitler's missing testicle is displayed as a war trophy in the Royal Albert Hall.

The author of the lyrics is unknown, though several claims have been made. The song first appeared among British soldiers in 1939 and was quickly taken up by Allied military and civilians. Its familiarity increased after its use in a scene in the 1957 film The Bridge on the River Kwai. The song has been cited as an example of morally-correct disrespect that used political mockery to boost morale in wartime.

🔗 Linguistics

Ghoti is a creative respelling of the word fish, used to illustrate irregularities in English spelling and pronunciation.

🔗 Biography 🔗 Energy 🔗 Pennsylvania 🔗 Lehigh Valley

Edwin Laurentine Drake (March 29, 1819 – November 9, 1880), also known as Colonel Drake, was an American businessman and the first American to successfully drill for oil.

🔗 Birds

Brood parasites are organisms that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, using brood mimicry, for example by having eggs that resemble the host's (egg mimicry).

Brood parasitism relieves the parasitic parents from the investment of rearing young or building nests for the young, enabling them to spend more time on other activities such as foraging and producing further offspring. Bird parasite species mitigate the risk of egg loss by distributing eggs amongst a number of different hosts. As this behaviour damages the host, it often results in an evolutionary arms race between parasite and host as the pair of species coevolve.

The strength of defenses and counter-adaptation rely on the host/parasitic species' ability to evolve; some host species have very strong rejection defenses resulting in the parasitic species evolving to have very close mimicry. In other species, hosts do not show rejection defenses and as a result, the parasitic species will show no evolved trait (example: egg mimicry).

🔗 Computing 🔗 Microsoft Windows 🔗 Microsoft Windows/Computing 🔗 Microsoft

Resilient File System (ReFS), codenamed "Protogon", is a Microsoft proprietary file system introduced with Windows Server 2012 with the intent of becoming the "next generation" file system after NTFS.

ReFS was designed to overcome problems that had become significant over the years since NTFS was conceived, which are related to how data storage requirements had changed. The key design advantages of ReFS include automatic integrity checking and data scrubbing, removal of the need for running chkdsk, protection against data degradation, built-in handling of hard disk drive failure and redundancy, integration of RAID functionality, a switch to copy/allocate on write for data and metadata updates, handling of very long paths and filenames, and storage virtualization and pooling, including almost arbitrarily sized logical volumes (unrelated to the physical sizes of the used drives).

These requirements arose from two major changes in storage systems and usage – the size of storage in use (large or massive arrays of multi-terabyte drives now being fairly common), and the need for continual reliability. As a result, the file system needs to be self-repairing (to prevent disk checking from being impractically slow or disruptive), along with abstraction or virtualization between physical disks and logical volumes.

ReFS was initially added to Windows Server 2012 only, with the aim of gradual migration to consumer systems in future versions; this was achieved as of Windows 8.1. The initial versions removed some NTFS features, such as disk quotas, alternate data streams, and extended attributes. Some of these were re-implemented in later versions of ReFS.

In early versions (2012–2013), ReFS was similar to or slightly faster than NTFS in most tests, but far slower when full integrity checking was enabled, a result attributed to the relative newness of ReFS. Pre-release concerns were also voiced by one blogger over Storage Spaces, the storage system designed to underpin ReFS, which reportedly could fail in a manner that prevented ReFS from recovering automatically.

The ability to create ReFS volumes was removed in Windows 10's 2017 Fall Creators Update for all editions except Enterprise and Pro for Workstations.

The cluster size of a ReFS volume is either 4 KiB or 64 KiB.

🔗 United States 🔗 Organizations

An important part of the counterculture of the 1970s, Project One, sometimes described as a technological commune, was an intentional community in San Francisco, California, U.S. Located at 1380 Howard St. in an 84,000 square foot warehouse, formerly an abandoned candy factory, the community functioned from 1970 to 1980 and was the first "warehouse community" in San Francisco. Occupied by a shifting mix of students, craftspeople, artisans, sculptors, filmmakers, and technologists, Project One was anchored by a number of organizations.

The community had no formal organizational structure. Decisions were made through a voluntary weekly meeting of members who made decisions based on a consensus of those present.

Project One was initiated by architect Ralph Scott, a former student of Buckminster Fuller, and rapidly became an interdisciplinary learning environment. Central to the concept was Symbas Alternative High School, founded by Scott and located in a large, high-ceiling space on the first floor. Many of these resident non-profit organizations and small businesses were brought in to serve as resources for the students, who were also members of the larger community. Students found mentors who offered skills training and the opportunities to practice new skills. See also community of place.