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Lamport Timestamps
The algorithm of Lamport timestamps is a simple algorithm used to determine the order of events in a distributed computer system. As different nodes or processes will typically not be perfectly synchronized, this algorithm is used to provide a partial ordering of events with minimal overhead, and conceptually provide a starting point for the more advanced vector clock method. They are named after their creator, Leslie Lamport. Distributed algorithms such as resource synchronization often depend on some method of ordering events to function. For example, consider a system with two processes and a disk. The processes send messages to each other, and also send messages to the disk requesting access. The disk grants access in the order the messages were sent. For example process [math]\displaystyle{ A }[/math] sends a message to the disk requesting write access, and then sends a read instruction message to process [math]\displaystyle{ B }[/math]. Process [math]\displaystyle{ B }[/math] receives the message, and as a result sends its own read request message to the disk. If there is a timing delay causing the disk to receive both messages at the same time, it can determine which message happened-before the other: [math]\displaystyle{ A }[/math] happens-before [math]\displaystyle{ B }[/math] if one can get from [math]\displaystyle{ A }[/math] to [math]\displaystyle{ B }[/math] by a sequence of moves of two types: moving forward while remaining in the same process, and following a message from its sending to its reception. A logical clock algorithm provides a mechanism to determine facts about the order of such events. Lamport invented a simple mechanism by which the happened-before ordering can be captured numerically. A Lamport logical clock is a numerical software counter value maintained in each process. Conceptually, this logical clock can be thought of as a clock that only has meaning in relation to messages moving between processes. When a process receives a message, it re-synchronizes its logical clock with that sender. The above-mentioned vector clock is a generalization of the idea into the context of an arbitrary number of parallel, independent processes.
  • 1.4K
  • 24 Oct 2022
Topic Review
Shinbutsu-shūgō
Shinbutsu-shūgō (神仏習合, "syncretism of kami and buddhas"), also called Shinbutsu-konkō (神仏混淆, "jumbling up" or "contamination of kami and buddhas"), is the syncretism of Buddhism and kami worship that was Japan's only organized religion up until the Meiji period. Beginning in 1868, the new Meiji government approved a series of laws that separated Japanese native kami worship, on one side, from Buddhism which had assimilated it, on the other. When Buddhism was introduced from China in the Asuka period (6th century), rather than discarding the old belief system, the Japanese tried to reconcile the two, assuming both were true. As a consequence, Buddhist temples (寺, tera) were attached to local Shinto shrines (神社, jinja) and vice versa and devoted to both kami and buddhas. The local religion and foreign Buddhism never quite fused, but remained however inextricably linked all the way to the present day, always interacting. The depth of the resulting influence of Buddhism on local religious beliefs can be seen for example in the fact that much of Shinto's conceptual vocabulary and even the types of Shinto shrines we see today, with a large worship hall and religious images, are themselves of Buddhist origin. The formal separation of Buddhism from Shinto took place only as recently as the end of the 19th century; however, in many ways, the blending of the two still continues. The term shinbutsu shūgō itself was coined during the early modern era (17th century) to refer to the amalgamation of kami and buddhas in general, as opposed to specific currents within Buddhism which did the same, e.g. Ryōbu Shintō and Sannō Shintō. The term may have a negative connotation of bastardization and randomness.
  • 2.6K
  • 24 Oct 2022
Topic Review
Sound Transmission Class
Sound Transmission Class (or STC) is an integer rating of how well a building partition attenuates airborne sound. In the US, it is widely used to rate interior partitions, ceilings, floors, doors, windows and exterior wall configurations. Outside the US, the Sound Reduction Index (SRI) ISO index is used. The STC rating very roughly reflects the decibel reduction of noise that a partition can provide. The STC is useful for evaluating annoyance due to speech sounds, but not music or machinery noise as these sources contain more low frequency energy than speech. There are many ways to improve the sound transmission class of a partition, though the two most basic principles are adding mass and increasing the overall thickness. In general, the sound transmission class of a double leaf wall (e.g. two 4"-thick brick walls separated by a 2" airspace) is greater than a single wall of equivalent mass (e.g. homogeneous 8" brick wall).
  • 2.3K
  • 24 Oct 2022
Topic Review
L-Photo-Leucine
L-Photo-Leucine is a synthetic derivative of the L-Leucine amino acid that is used as its natural analog and is characterized for having photo-reactivity, which makes it suitable for observing and characterizing protein-protein interactions (PPI). When a protein containing this amino acid (A) is lightened with ultraviolet light while interacting with another protein (B), the complex formed from these two proteins (AB) remains attached and can be isolated for its study. Photo Leucine, as well as another photo-reactive amino acid derived from Methionine, Photo-Methionine, were first synthesized in 2005 by Monika Suchanek, Anna Radzikoska and Christoph Thiele from the Max Planck Institute of Molecular Cell Biology and Genetics with the objective of identifying protein to protein interaction throughout a simple western blot test that would provide high specificity. The resemblance of the photo-reactive amino acids to the natural ones allows the former ones to avoid the extensive control mechanisms that take place during the protein synthesis within the cell.
  • 762
  • 24 Oct 2022
Topic Review
APT (Package Manager)
Advanced Package Tool, or APT, is a free-software user interface that works with core libraries to handle the installation and removal of software on Debian, Ubuntu, and related Linux distributions. APT simplifies the process of managing software on Unix-like computer systems by automating the retrieval, configuration and installation of software packages, either from precompiled files or by compiling source code.
  • 2.5K
  • 24 Oct 2022
Topic Review
GNU Bison
GNU bison, commonly known as Bison, is a parser generator that is part of the GNU Project. Bison reads a specification of a context-free language, warns about any parsing ambiguities, and generates a parser (either in C, C++, or Java) which reads sequences of tokens and decides whether the sequence conforms to the syntax specified by the grammar. Bison by default generates LALR parsers but can also create GLR parsers. In POSIX mode, Bison is compatible with Yacc, but also has several extensions over this earlier program. Flex, an automatic lexical analyser, is often used with Bison, to tokenise input data and provide Bison with tokens. Bison was originally written by Robert Corbett in 1985. Later, in 1989, Robert Corbett released another parser generator named Berkeley Yacc. Bison was made Yacc-compatible by Richard Stallman. Bison is free software and is available under the GNU General Public License, with an exception (discussed below) allowing its generated code to be used without triggering the copyleft requirements of the licence.
  • 1.1K
  • 24 Oct 2022
Topic Review
Fractional Schrödinger Equation
The fractional Schrödinger equation is a fundamental equation of fractional quantum mechanics. It was discovered by Nick Laskin (1999) as a result of extending the Feynman path integral, from the Brownian-like to Lévy-like quantum mechanical paths. The term fractional Schrödinger equation was coined by Nick Laskin.
  • 3.1K
  • 24 Oct 2022
Topic Review
Fyne
Fyne is a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs) across desktop and mobile platforms. Fyne uses OpenGL to provide cross-platform graphics. It is inspired by the principles of Material Design to create applications that look and behave consistently across all platforms. It is licensed under the terms of the 3-clause BSD License, supporting the creation of free and proprietary applications. In December 2019 Fyne became the most popular GUI toolkit for Go, by GitHub star count and in early February 2020 it was trending as #1 project in GitHub trending ranks.
  • 2.1K
  • 24 Oct 2022
Topic Review
Frédérique Constant
Frédérique Constant SA is a Swiss manufacture of luxury wristwatches based in Plan-les-Ouates, Geneva. It was acquired in 2016 by Citizen Holdings of Tokyo, Japan. The company was established in 1988 by Peter Stas and Aletta Stas-Bax (a Dutch married couple). Before the sale to Citizen, Frédérique Constant SA was owned by Union Horlogère Holding B.V., which also owned Alpina Watches International SA, and Ateliers deMonaco SA, and was, in turn, owned by Frédérique Constant Holding SA.
  • 2.7K
  • 24 Oct 2022
Topic Review
Proprietary Device Driver
A proprietary device driver is a closed-source device driver published only in binary code. In the context of free and open-source software, a closed-source device driver is referred to as a blob or binary blob. The term usually refers to a closed-source kernel module loaded into the kernel of an open-source operating system, and is sometimes also applied to code running outside the kernel, such as system firmware images, microcode updates, or userland programs. The term blob was first used in database management systems to describe a collection of binary data stored as a single entity. When computer hardware vendors provide complete technical documentation for their products, operating system developers are able to write hardware device drivers to be included in the operating system kernels. However, some vendors, such as Nvidia, do not provide complete documentation for some of their products and instead provide binary-only drivers. This practice is most common for accelerated graphics drivers, wireless networking devices, and hardware RAID controllers. Most notably, binary blobs are very uncommon for non-wireless network interface controllers, which can almost always be configured via standard utilities (like ifconfig) out of the box; Theo de Raadt of OpenBSD attributes this to the work done by a single FreeBSD developer.
  • 2.4K
  • 24 Oct 2022
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