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In machine learning, the kernel embedding of distributions (also called the kernel mean or mean map) comprises a class of nonparametric methods in which a probability distribution is represented as an element of a reproducing kernel Hilbert space (RKHS). A generalization of the individual data-point feature mapping done in classical kernel methods, the embedding of distributions into infinite-dimensional feature spaces can preserve all of the statistical features of arbitrary distributions, while allowing one to compare and manipulate distributions using Hilbert space operations such as inner products, distances, projections, linear transformations, and spectral analysis. This learning framework is very general and can be applied to distributions over any space ${\displaystyle \Omega }$ on which a sensible kernel function (measuring similarity between elements of ${\displaystyle \Omega }$) may be defined. For example, various kernels have been proposed for learning from data which are: vectors in ${\displaystyle \mathbb {R} ^{d}}$, discrete classes/categories, strings, graphs/networks, images, time series, manifolds, dynamical systems, and other structured objects. The theory behind kernel embeddings of distributions has been primarily developed by Alex Smola, Le Song , Arthur Gretton, and Bernhard Schölkopf. A review of recent works on kernel embedding of distributions can be found in.

The analysis of distributions is fundamental in machine learning and statistics, and many algorithms in these fields rely on information theoretic approaches such as entropy, mutual information, or Kullback–Leibler divergence. However, to estimate these quantities, one must first either perform density estimation, or employ sophisticated space-partitioning/bias-correction strategies which are typically infeasible for high-dimensional data. Commonly, methods for modeling complex distributions rely on parametric assumptions that may be unfounded or computationally challenging (e.g. Gaussian mixture models), while nonparametric methods like kernel density estimation (Note: the smoothing kernels in this context have a different interpretation than the kernels discussed here) or characteristic function representation (via the Fourier transform of the distribution) break down in high-dimensional settings.

Methods based on the kernel embedding of distributions sidestep these problems and also possess the following advantages:

1. Data may be modeled without restrictive assumptions about the form of the distributions and relationships between variables
2. Intermediate density estimation is not needed
3. Practitioners may specify the properties of a distribution most relevant for their problem (incorporating prior knowledge via choice of the kernel)
4. If a characteristic kernel is used, then the embedding can uniquely preserve all information about a distribution, while thanks to the kernel trick, computations on the potentially infinite-dimensional RKHS can be implemented in practice as simple Gram matrix operations
5. Dimensionality-independent rates of convergence for the empirical kernel mean (estimated using samples from the distribution) to the kernel embedding of the true underlying distribution can be proven.
6. Learning algorithms based on this framework exhibit good generalization ability and finite sample convergence, while often being simpler and more effective than information theoretic methods

Thus, learning via the kernel embedding of distributions offers a principled drop-in replacement for information theoretic approaches and is a framework which not only subsumes many popular methods in machine learning and statistics as special cases, but also can lead to entirely new learning algorithms.

The phonautograph is the earliest known device for recording sound. Previously, tracings had been obtained of the sound-producing vibratory motions of tuning forks and other objects by physical contact with them, but not of actual sound waves as they propagated through air or other media. Invented by Frenchman Édouard-Léon Scott de Martinville, it was patented on March 25, 1857. It transcribed sound waves as undulations or other deviations in a line traced on smoke-blackened paper or glass. Intended solely as a laboratory instrument for the study of acoustics, it could be used to visually study and measure the amplitude envelopes and waveforms of speech and other sounds, or to determine the frequency of a given musical pitch by comparison with a simultaneously recorded reference frequency.

Apparently, it did not occur to anyone before the 1870s that the recordings, called phonautograms, contained enough information about the sound that they could, in theory, be used to recreate it. Because the phonautogram tracing was an insubstantial two-dimensional line, direct physical playback was impossible in any case.

Several phonautograms recorded before 1861 were successfully played as sound in 2008 by optically scanning them and using a computer to process the scans into digital audio files.

The Satellaview is a satellite modem peripheral produced by Nintendo for the Super Famicom in 1995. Containing 1 megabit of ROM space and an additional 512K of RAM, Satellaview allowed players to download games, magazines and other forms of content through satellite broadcasts provided by Japanese company St.GIGA. To use Satellaview, players had to purchase a special broadcast satellite (BS) tuner directly from St.GIGA or rent one for a six-month fee, and to pay monthly maintenance fees to both St.GIGA and Nintendo. It was attached to the bottom of the Super Famicom via the system's expansion port. It featured heavy support from third-party developers, including Squaresoft, Taito, Konami, Capcom and Seta.

Satellaview was the result of a collaboration between Nintendo and St.GIGA, the latter being known in Japan for its "Tide of Sound" nature sound music. By 1994, St.GIGA was struggling financially due to the Japanese Recession affecting the demand for its music; Nintendo initiated a "rescue" plan by purchasing a stake in the company. Satellaview was produced by Nintendo Research & Development 2, the same team that designed the Super Famicom itself, and was made to cater towards a more adult-oriented market. By 1998, Nintendo's relationship with St.GIGA was beginning to collapse due to the company refusing to go forward with a debt-management plan and failing to secure a government broadcasting license. Nintendo withdrew support for Satellaview in March 1999, with St.GIGA continuing to supply content until June 30, 2000, when it was ultimately discontinued.

The rise of technologically-superior consoles such as the Sega Saturn and PlayStation and its high cost made consumers reluctant to purchase Satellaview, especially due to it only being sold via mail order, or through specific electronic store chains. Despite this, St.GIGA reported seeing over 100,000 subscribers by March 1997. Retrospectively, Satellaview has been praised by critics for its technological accomplishments and the overall quality of its games, particularly those from the Legend of Zelda series. In recent years, it has gained a strong cult following due to much of its content being deemed lost, with video game preservation groups being formed to dump and preserve its games and other services online.

A nanoscale vacuum-channel transistor (NVCT) is a theoretically visioned transistor in which the electron transport medium is a vacuum. In a traditional solid-state transistor, a semiconductor channel exists between the source and the drain, and the current flows through the semiconductor. However, in a nanoscale vacuum-channel transistor, no material exists between the source and the drain, and therefore, the current flows through the vacuum. However, experimental realization of such a transistor has not been demonstrated.

Theoretically, a vacuum-channel transistor is expected to operate faster than a traditional solid-state transistor, and have higher power output. Moreover, vacuum-channel transistors are expected to operate at higher temperature and radiation level than a traditional transistor making them suitable for space application.

The development of vacuum-channel transistors is still at a very early research stage, and there are only limited study in recent literature such as vertical field-emitter vacuum-channel transistor, gate-insulated planar electrodes vacuum-channel transistor, vertical vacuum-channel transistor, and all-around gate vacuum-channel transistor.

EPUB is an e-book file format that uses the ".epub" file extension. The term is short for electronic publication and is sometimes styled ePub. EPUB is supported by many e-readers, and compatible software is available for most smartphones, tablets, and computers. EPUB is a technical standard published by the International Digital Publishing Forum (IDPF). It became an official standard of the IDPF in September 2007, superseding the older Open eBook standard.

The Book Industry Study Group endorses EPUB 3 as the format of choice for packaging content and has stated that the global book publishing industry should rally around a single standard. The EPUB format is implemented as an archive file consisting of XHTML files carrying the content, along with images and other supporting files. EPUB is the most widely supported vendor-independent XML-based (as opposed to PDF) e-book format; that is, it is supported by almost all hardware readers, except for Kindle.

The sturddlefish is a hybrid of the American paddlefish (Polyodon spathula) and the Russian sturgeon (Acipenser gueldenstaedtii), accidentally created by researchers in 2019 and announced in 2020. Obtaining living hybrids through breeding individuals from different families is unusual, especially given that the two species' last common ancestor lived 184 million years ago. The hybrids were created accidentally during attempts to induce gynogenesis, a type of parthenogenic reproduction where a sperm cell must be present to trigger embryogenesis but does not genetically contribute to the offspring. Hundreds of hybrid fish were created, of which about two-thirds survived over one month, and about 100 survived for one year. As of July 2020, all living hybrid fish are living in captivity at the research lab in Hungary. There are no further plans to create new sturddlefish.

Oi is an interjection used in various varieties of the English language, particularly Australian English, British English, Indian English, Irish English, New Zealand English, and South African English, as well as non-English languages such as Chinese, Tagalog, Tamil, Hindi/Urdu, Japanese, and Portuguese to get the attention of another person or to express surprise or disapproval. It is sometimes used in Canadian English and very rarely in American English. The word is also common in the Indian subcontinent, where it has varied pronunciations of "O-ee" and "O-ye".

"Oi" has been particularly associated with working class and Cockney speech. It is effectively a local pronunciation of "hoy" (see H-dropping), an older expression. A study of the Cockney dialect in the 1950s found that whether it was being used to call attention or as a challenge depended on its tone and abruptness. The study's author noted that the expression is "jaunty and self-assertive" as well as "intensely cockney".

A poll of non-English speakers by the British Council in 2004 found that "oi" was considered the 61st most beautiful word in the English language. A spokesman commented that "Oi is not a word that I would've thought turned up in English manuals all that often." "Oi" was added to the list of acceptable words in US Scrabble in 2006.

The Symmetry454 calendar (Sym454) is a proposal for calendar reform created by Irv Bromberg of the University of Toronto, Canada. It is a perennial solar calendar that conserves the traditional month pattern and 7-day week, has symmetrical equal quarters in 82% of the years in its 293-year cycle, and starts every month on Monday.

John Titor (May 5, 6 or 7, 1998) is a name used on several bulletin boards during 2000 and 2001 by a poster claiming to be an American military time traveler from 2036. Titor made numerous vague and specific predictions regarding calamitous events in 2004 and beyond, including a nuclear war, none of which came true. Subsequent closer examination of Titor's assertions provoked widespread skepticism. Inconsistencies in his explanations, the uniform inaccuracy of his predictions, and a private investigator's findings all led to the general impression that the entire episode was an elaborate hoax. A 2009 investigation concluded that Titor was likely the creation of Larry Haber, a Florida entertainment lawyer, along with his brother Morey, a computer scientist.