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In geology, lamination () is a small-scale sequence of fine layers (: laminae; : lamina) that occurs in sedimentary rocks. Laminae are normally smaller and less pronounced than bedding. Lamination is often regarded as planar structures one centimetre or less in thickness, whereas bedding layers are greater than one cen... | Lamination (geology) | Wikipedia | 443 | 24318825 | https://en.wikipedia.org/wiki/Lamination%20%28geology%29 | Physical sciences | Sedimentology | Earth science |
A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, niobium, rhenium, tantalum, tellurium, tin, titanium, tungsten, vanad... | Native metal | Wikipedia | 411 | 6742209 | https://en.wikipedia.org/wiki/Native%20metal | Physical sciences | Minerals | Earth science |
Gold
Most gold is mined as native metal and can be found as nuggets, veins or wires of gold in a rock matrix, or fine grains of gold, mixed in with sediments or bound within rock. The iconic image of gold mining for many is gold panning, which is a method of separating flakes and nuggets of pure gold from river sedimen... | Native metal | Wikipedia | 491 | 6742209 | https://en.wikipedia.org/wiki/Native%20metal | Physical sciences | Minerals | Earth science |
The same deposits of native copper on the Keweenaw Peninsula and Isle Royale were later mined commercially. From 1845 until 1887, the Michigan Copper Country was the leading producer of copper in the United States. Masses of native copper weighing hundreds of tons were sometimes found in the mines.
The spectrum of c... | Native metal | Wikipedia | 492 | 6742209 | https://en.wikipedia.org/wiki/Native%20metal | Physical sciences | Minerals | Earth science |
The Everglades crayfish (Procambarus alleni), sometimes called the Florida crayfish, the blue crayfish, the electric blue crayfish, or the sapphire crayfish, is a species of freshwater crayfish endemic to Florida in the United States. Its natural range is the area east of St. Johns River and all of Florida from Levy Co... | Procambarus alleni | Wikipedia | 192 | 6746613 | https://en.wikipedia.org/wiki/Procambarus%20alleni | Biology and health sciences | Crayfishes and lobsters | Animals |
A material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geological origin or biological function. Materials science is the study of materia... | Material | Wikipedia | 502 | 6748280 | https://en.wikipedia.org/wiki/Material | Physical sciences | Substance | Chemistry |
In foams and textiles, the chemical structure is less relevant to immediately observable properties than larger-scale material features: the holes in foams, and the weave in textiles.
Classification by properties
Materials can be compared and classified by their large-scale physical properties.
Mechanical properties... | Material | Wikipedia | 153 | 6748280 | https://en.wikipedia.org/wiki/Material | Physical sciences | Substance | Chemistry |
Salvia () is the largest genus of plants in the sage family Lamiaceae, with nearly 1,000 species of shrubs, herbaceous perennials, and annuals. Within the Lamiaceae, Salvia is part of the tribe Mentheae within the subfamily Nepetoideae. One of several genera, commonly referred to as sage, it includes two widely used h... | Salvia | Wikipedia | 425 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
The flowers are produced in racemes or panicles, and generally produce a showy display with flower colors ranging from blue to red, with white and yellow less common. The calyx is normally tubular or bell shaped, without bearded throats, and divided into two parts or lips, the upper lip entire or three-toothed, the low... | Salvia | Wikipedia | 270 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
The defining characteristic of the genus Salvia is the unusual pollination mechanism. It is central to any investigation into the systematics, species distribution, or pollination biology of Salvia. It consists of two stamens (instead of the typical four found in other members of the tribe Mentheae) and the two thecae ... | Salvia | Wikipedia | 369 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
History
George Bentham was first to give a full monographic account of the genus in 1832–1836, and based his classifications on staminal morphology. Bentham's work on classifying the family Labiatae (Labiatarum Genera et Species (1836)) is still the only comprehensive and global organization of the family. While he wa... | Salvia | Wikipedia | 485 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
Phylogenetic analyses
Through DNA sequencing, Salvia was shown to not be monophyletic but to consist of three separate clades (Salvia clades I–III) each with different sister groups. They also found that the staminal lever mechanism evolved at least two separate times, through convergent evolution. Walker and Sytsma (... | Salvia | Wikipedia | 510 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
Many species are used as herbs, as ornamental plants (usually for flower interest), and sometimes for their ornamental and aromatic foliage. Some species, such as Salvia columbariae and Salvia hispanica, are also grown for their seeds. The Plant List has 986 accepted species names. A selection of some well-known specie... | Salvia | Wikipedia | 70 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
Salvia apiana: white sage; sacred to a number of Native American peoples, and used by some tribes in their ceremoniesSalvia azurea: blue sageSalvia buchananii: Buchanan sage; woody-based stoloniferous perennial, deep pink flowersSalvia cacaliifolia: blue vine sage or Guatemalan sage; pure gentian-blue flowersSalvia can... | Salvia | Wikipedia | 512 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
blue flowersSalvia sclarea: clary; grown as an ornamental and to some extent for perfume oilsSalvia spathacea: California hummingbird sage, pitcher sage; ornamental, fruit-scented with rose pink flowersSalvia splendens: scarlet sage; popular tender ornamental bedding or pot plant | Salvia | Wikipedia | 62 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
Salvia uliginosa: bog sage; herbaceous perennial, blue flowers | Salvia | Wikipedia | 16 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
Ecology
HerbivorySalvia species are used as food plants by the larvae of some Lepidoptera (butterfly and moth) species including the bucculatricid leaf-miner Bucculatrix taeniola which feeds exclusively on the genus and the Coleophora case-bearers C. aegyptiacae, C. salviella (both feed exclusively on Salvia aegyptiaca... | Salvia | Wikipedia | 501 | 21346360 | https://en.wikipedia.org/wiki/Salvia | Biology and health sciences | Lamiales | null |
A kernel is a computer program at the core of a computer's operating system that always has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory... | Kernel (operating system) | Wikipedia | 485 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
This central component of a computer system is responsible for executing programs. The kernel takes responsibility for deciding at any time which of the many running programs should be allocated to the processor or processors.
Random-access memory
Random-access memory (RAM) is used to store both program instructions ... | Kernel (operating system) | Wikipedia | 454 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
On many systems, a program's virtual address may refer to data which is not currently in memory. The layer of indirection provided by virtual addressing allows the operating system to use other data stores, like a hard drive, to store what would otherwise have to remain in main memory (RAM). As a result, operating syst... | Kernel (operating system) | Wikipedia | 499 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
And at the software level, device driver abstractions include:
Allowing the operating system direct access to hardware resources
Only implementing primitives
Implementing an interface for non-driver software such as TWAIN
Implementing a language (often a high-level language such as PostScript)
For example, to show... | Kernel (operating system) | Wikipedia | 411 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
A system call is a mechanism that is used by the application program to request a service from the operating system. They use a machine-code instruction that causes the processor to change mode. An example would be from supervisor mode to protected mode. This is where the operating system performs actions like accessin... | Kernel (operating system) | Wikipedia | 493 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
The mechanisms or policies provided by the kernel can be classified according to several criteria, including: static (enforced at compile time) or dynamic (enforced at run time); pre-emptive or post-detection; according to the protection principles they satisfy (e.g., Denning); whether they are hardware supported or la... | Kernel (operating system) | Wikipedia | 501 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
If the firmware does not support protection mechanisms, it is possible to simulate protection at a higher level, for example by simulating capabilities by manipulating page tables, but there are performance implications. Lack of hardware support may not be an issue, however, for systems that choose to use language-base... | Kernel (operating system) | Wikipedia | 426 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Advantages of this approach include:
No need for separate address spaces. Switching between address spaces is a slow operation that causes a great deal of overhead, and a lot of optimization work is currently performed in order to prevent unnecessary switches in current operating systems. Switching is completely unnec... | Kernel (operating system) | Wikipedia | 418 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Similar to physical memory, allowing applications direct access to controller ports and registers can cause the controller to malfunction, or system to crash. With this, depending on the complexity of the device, some devices can get surprisingly complex to program, and use several different controllers. Because of thi... | Kernel (operating system) | Wikipedia | 430 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Per Brinch Hansen presented arguments in favour of separation of mechanism and policy. The failure to properly fulfill this separation is one of the major causes of the lack of substantial innovation in existing operating systems, a problem common in computer architecture. The monolithic design is induced by the "kerne... | Kernel (operating system) | Wikipedia | 435 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Monolithic kernels, which have traditionally been used by Unix-like operating systems, contain all the operating system core functions and the device drivers. A monolithic kernel is one single program that contains all of the code necessary to perform every kernel-related task. Every part which is to be accessed by mos... | Kernel (operating system) | Wikipedia | 425 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
These types of kernels consist of the core functions of the operating system and the device drivers with the ability to load modules at runtime. They provide rich and powerful abstractions of the underlying hardware. They provide a small set of simple hardware abstractions and use applications called servers to provide... | Kernel (operating system) | Wikipedia | 307 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Microkernel (also abbreviated μK or uK) is the term describing an approach to operating system design by which the functionality of the system is moved out of the traditional "kernel", into a set of "servers" that communicate through a "minimal" kernel, leaving as little as possible in "system space" and as much as pos... | Kernel (operating system) | Wikipedia | 486 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Most microkernels use a message passing system to handle requests from one server to another. The message passing system generally operates on a port basis with the microkernel. As an example, if a request for more memory is sent, a port is opened with the microkernel and the request sent through. Once within the micro... | Kernel (operating system) | Wikipedia | 456 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Larger running memory footprint
More software for interfacing is required, there is a potential for performance loss.
Messaging bugs can be harder to fix due to the longer trip they have to take versus the one off copy in a monolithic kernel.
Process management in general can be very complicated.
The disadvantages ... | Kernel (operating system) | Wikipedia | 479 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
The performance of microkernels was poor in both the 1980s and early 1990s. However, studies that empirically measured the performance of these microkernels did not analyze the reasons of such inefficiency. The explanations of this data were left to "folklore", with the assumption that they were due to the increased fr... | Kernel (operating system) | Wikipedia | 277 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Hybrid kernels are used in most commercial operating systems such as Microsoft Windows NT 3.1, NT 3.5, NT 3.51, NT 4.0, 2000, XP, Vista, 7, 8, 8.1 and 10. Apple's own macOS uses a hybrid kernel called XNU, which is based upon code from OSF/1's Mach kernel (OSFMK 7.3) and FreeBSD's monolithic kernel. Hybrid kernels are ... | Kernel (operating system) | Wikipedia | 462 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Modules, generally, communicate with the kernel using a module interface of some sort. The interface is generalized (although particular to a given operating system) so it is not always possible to use modules. Often the device drivers may need more flexibility than the module interface affords. Essentially, it is two ... | Kernel (operating system) | Wikipedia | 474 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Strictly speaking, an operating system (and thus, a kernel) is not required to run a computer. Programs can be directly loaded and executed on the "bare metal" machine, provided that the authors of those programs are willing to work without any hardware abstraction or operating system support. Most early computers oper... | Kernel (operating system) | Wikipedia | 440 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
The Commodore Amiga was released in 1985, and was among the first and certainly most successful home computers to feature an advanced kernel architecture. The AmigaOS kernel's executive component, exec.library, uses a microkernel message-passing design, but there are other kernel components, like graphics.library, tha... | Kernel (operating system) | Wikipedia | 443 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Over the years the computing model changed, and Unix's treatment of everything as a file or byte stream no longer was as universally applicable as it was before. Although a terminal could be treated as a file or a byte stream, which is printed to or read from, the same did not seem to be true for a graphical user inter... | Kernel (operating system) | Wikipedia | 477 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
Microsoft also developed Windows NT, an operating system with a very similar interface, but intended for high-end and business users. This line started with the release of Windows NT 3.1 in 1993, and was introduced to general users with the release of Windows XP in October 2001—replacing Windows 9x with a completely di... | Kernel (operating system) | Wikipedia | 462 | 21346982 | https://en.wikipedia.org/wiki/Kernel%20%28operating%20system%29 | Technology | Operating systems | null |
A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command ... | Unix-like | Wikipedia | 458 | 21347057 | https://en.wikipedia.org/wiki/Unix-like | Technology | Operating Systems | null |
"Unix-like" systems started to appear in the late 1970s and early 1980s. Many proprietary versions, such as Idris (1978), UNOS (1982), Coherent (1983), and UniFlex (1985), aimed to provide businesses with the functionality available to academic users of UNIX.
When AT&T allowed relatively inexpensive commercial binary ... | Unix-like | Wikipedia | 444 | 21347057 | https://en.wikipedia.org/wiki/Unix-like | Technology | Operating Systems | null |
Trademark or branded UNIX
These systemslargely commercial in naturehave been determined by the Open Group to meet the Single UNIX Specification and are allowed to carry the UNIX name. Most such systems are commercial derivatives of the System V code base in one form or another, although Apple macOS 10.5 and later is a... | Unix-like | Wikipedia | 336 | 21347057 | https://en.wikipedia.org/wiki/Unix-like | Technology | Operating Systems | null |
Compatibility layers
Some non-Unix-like operating systems provide a Unix-like compatibility layer, with varying degrees of Unix-like functionality.
IBM z/OS's UNIX System Services is sufficiently complete as to be certified as trademark UNIX.
Cygwin, MSYS, and MSYS2 each provide a GNU environment on top of the Micros... | Unix-like | Wikipedia | 461 | 21347057 | https://en.wikipedia.org/wiki/Unix-like | Technology | Operating Systems | null |
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix... | Unix | Wikipedia | 325 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
Version 7 in 1979 was the final widely released Research Unix, after which AT&T sold UNIX System III, based on Version 7, commercially in 1982; to avoid confusion between the Unix variants, AT&T combined various versions developed by others and released it as UNIX System V in 1983. However as these were closed-source, ... | Unix | Wikipedia | 445 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
At first, Unix was not designed to support multi-tasking or to be portable. Later, Unix gradually gained multi-tasking and multi-user capabilities in a time-sharing configuration, as well as portability. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file syst... | Unix | Wikipedia | 382 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
The origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology, Bell Labs, and General Electric were developing Multics, a time-sharing operating system for the GE 645 mainframe computer.
Multics featured several innovations, but also presented severe problems. Frustrated by the size and ... | Unix | Wikipedia | 413 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (BSD and System V) by commercial startups, which in turn led to Unix fragmenting into multiple, similar — but often slightly and mutually incompatible — systems including DYNIX, HP-UX, SunOS/Solaris, AIX... | Unix | Wikipedia | 450 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
The Unix system is composed of several components that were originally packaged together. By including the development environment, libraries, documents and the portable, modifiable source code for all of these components, in addition to the kernel of an operating system, Unix was a self-contained software system. This... | Unix | Wikipedia | 161 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
The names and filesystem locations of the Unix components have changed substantially across the history of the system. Nonetheless, the V7 implementation has the canonical early structure:
Kernel source code in /usr/sys, composed of several sub-components:
conf configuration and machine-dependent parts, including boo... | Unix | Wikipedia | 492 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
sh the "shell" programmable command-line interpreter, the primary user interface on Unix before window systems appeared, and even afterward (within a "command window").
Utilities the core toolkit of the Unix command set, including cp, ls, grep, find and many others. Subcategories include:
System utilities administrat... | Unix | Wikipedia | 328 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
Impact
The Unix system had a significant impact on other operating systems. It achieved its reputation by its interactivity, by providing the software at a nominal fee for educational use, by running on inexpensive hardware, and by being easy to adapt and move to different machines. Unix was originally written in ass... | Unix | Wikipedia | 510 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
A fundamental simplifying assumption of Unix was its focus on newline-delimited text for nearly all file formats. There were no "binary" editors in the original version of Unix – the entire system was configured using textual shell command scripts. The common denominator in the I/O system was the byte – unlike "record-... | Unix | Wikipedia | 406 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
In 1983, Richard Stallman announced the GNU (short for "GNU's Not Unix") project, an ambitious effort to create a free software Unix-like system—"free" in the sense that everyone who received a copy would be free to use, study, modify, and redistribute it. The GNU project's own kernel development project, GNU Hurd, had... | Unix | Wikipedia | 485 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
OpenSolaris was the free software counterpart to Solaris developed by Sun Microsystems, which included a CDDL-licensed kernel and a primarily GNU userland. However, Oracle discontinued the project upon their acquisition of Sun, which prompted a group of former Sun employees and members of the OpenSolaris community to f... | Unix | Wikipedia | 365 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
AT&T did not allow licensees to use the Unix name; thus Microsoft called its variant Xenix, for example. In October 1993, Novell, the company that owned the rights to the Unix System V source at the time, transferred the trademarks of Unix to the X/Open Company (now The Open Group), and in 1995 sold the related busines... | Unix | Wikipedia | 482 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
Unix was the original formatting, but the usage of UNIX remains widespread because it was once typeset in small caps (Unix). According to Dennis Ritchie, when presenting the original Unix paper to the third Operating Systems Symposium of the American Association for Computing Machinery (ACM), "we had a new typesetter a... | Unix | Wikipedia | 295 | 21347364 | https://en.wikipedia.org/wiki/Unix | Technology | Operating systems | null |
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different su... | Chemical compound | Wikipedia | 425 | 21347411 | https://en.wikipedia.org/wiki/Chemical%20compound | Physical sciences | Chemistry | null |
Definitions
Any substance consisting of two or more different types of atoms (chemical elements) in a fixed stoichiometric proportion can be termed a chemical compound; the concept is most readily understood when considering pure chemical substances. It follows from their being composed of fixed proportions of two or... | Chemical compound | Wikipedia | 358 | 21347411 | https://en.wikipedia.org/wiki/Chemical%20compound | Physical sciences | Chemistry | null |
There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, which require the fixed ratios. Many solid chemical substances—for example many silicate minerals—are chemical substances, but do not have simple formulae reflec... | Chemical compound | Wikipedia | 461 | 21347411 | https://en.wikipedia.org/wiki/Chemical%20compound | Physical sciences | Chemistry | null |
Ionic compounds containing basic ions hydroxide (OH−) or oxide (O2−) are classified as bases. Ionic compounds without these ions are also known as salts and can be formed by acid–base reactions. Ionic compounds can also be produced from their constituent ions by evaporation of their solvent, precipitation, freezing, a ... | Chemical compound | Wikipedia | 405 | 21347411 | https://en.wikipedia.org/wiki/Chemical%20compound | Physical sciences | Chemistry | null |
A covalent bond, also known as a molecular bond, involves the sharing of electrons between two atoms. Primarily, this type of bond occurs between elements that fall close to each other on the periodic table of elements, yet it is observed between some metals and nonmetals. This is due to the mechanism of this type of b... | Chemical compound | Wikipedia | 352 | 21347411 | https://en.wikipedia.org/wiki/Chemical%20compound | Physical sciences | Chemistry | null |
Mac operating systems were developed by Apple Inc. in a succession of two major series.
In 1984, Apple debuted the operating system that is now known as the classic Mac OS with its release of the original Macintosh System Software. The system, rebranded Mac OS in 1997, was pre-installed on every Macintosh until 2002 a... | Mac operating systems | Wikipedia | 473 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
Apple launched several new operating systems based on the core of macOS, including iOS in 2007 for its iPhone, iPad, and iPod Touch mobile devices and in 2017 for its HomePod smart speakers; watchOS in 2015 for the Apple Watch; and tvOS in 2015 for the Apple TV set-top box.
Classic Mac OS
The classic Mac OS is the or... | Mac operating systems | Wikipedia | 442 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
The system was originally marketed as simply "version 10" of Mac OS, but it has a history that is largely independent of the classic Mac OS. It is a Unix-based operating system built on NeXTSTEP and other NeXT technology from the late 1980s until early 1997, when Apple purchased the company and its CEO Steve Jobs retur... | Mac operating systems | Wikipedia | 155 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
Desktop
The first version of the system was released on March 24, 2001, supporting the Aqua user interface. Since then, several more versions adding newer features and technologies have been released. Since 2011, new releases have been offered annually.
Mac OS X 10.0 – codenamed "Cheetah", released Saturday, March 24,... | Mac operating systems | Wikipedia | 452 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
Server
An early server computing version of the system was released in 1999 as a technology preview. It was followed by several more official server-based releases. Server functionality has instead been offered as an add-on for the desktop system since 2011.
Mac OS X Server 1.0 – code named "Hera", released in 1999
M... | Mac operating systems | Wikipedia | 495 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
The Star Trek project (as in "to boldly go where no Mac has gone before") was a secret prototype beginning in 1992, to port the classic Mac OS to Intel-compatible x86 personal computers. In partnership with Apple and with support from Intel, the project was instigated by Novell, which was looking to integrate its DR-DO... | Mac operating systems | Wikipedia | 415 | 21347643 | https://en.wikipedia.org/wiki/Mac%20operating%20systems | Technology | Operating Systems | null |
A unit of measurement, or unit of measure, is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement.
For example, a length is a p... | Unit of measurement | Wikipedia | 485 | 21347678 | https://en.wikipedia.org/wiki/Unit%20of%20measurement | Physical sciences | Measurement: General | null |
Weights and measures are mentioned in the Bible (Leviticus 19:35–36). It is a commandment to be honest and have fair measures.
In the Magna Carta of 1215 (The Great Charter) with the seal of King John, put before him by the Barons of England, King John agreed in Clause 35 "There shall be one measure of wine throughout... | Unit of measurement | Wikipedia | 465 | 21347678 | https://en.wikipedia.org/wiki/Unit%20of%20measurement | Physical sciences | Measurement: General | null |
As science progressed, a need arose to relate the measurement systems of different quantities, like length and weight and volume. The effort of attempting to relate different traditional systems between each other exposed many inconsistencies, and brought about the development of new units and systems.
Systems of unit... | Unit of measurement | Wikipedia | 511 | 21347678 | https://en.wikipedia.org/wiki/Unit%20of%20measurement | Physical sciences | Measurement: General | null |
While the above systems of units are based on arbitrary unit values, formalised as standards, natural units in physics are based on physical principle or are selected to make physical equations easier to work with. For example, atomic units (au) were designed to simplify the wave equation in atomic physics.
Some unusu... | Unit of measurement | Wikipedia | 512 | 21347678 | https://en.wikipedia.org/wiki/Unit%20of%20measurement | Physical sciences | Measurement: General | null |
.
There are certain rules that apply to units:
Only like terms may be added. When a unit is divided by itself, the division yields a unitless one. When two different units are multiplied or divided, the result is a new unit, referred to by the combination of the units. For instance, in SI, the unit of speed is metre... | Unit of measurement | Wikipedia | 502 | 21347678 | https://en.wikipedia.org/wiki/Unit%20of%20measurement | Physical sciences | Measurement: General | null |
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named in honor of James Watt (1736–1819), an 18th-century Scottish inventor, mechanical engineer, and chemist w... | Watt | Wikipedia | 471 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
In October 1908, at the International Conference on Electric Units and Standards in London, so-called international definitions were established for practical electrical units. Siemens' definition was adopted as the international watt. (Also used: 1 Ω.) The watt was defined as equal to 107 units of power in the practi... | Watt | Wikipedia | 222 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
Attowatt The sound intensity in water corresponding to the international standard reference sound pressure of 1 μPa is approximately 0.65 aW/m2.
Femtowatt Powers measured in femtowatts are typically found in references to radio and radar receivers. For example, meaningful FM tuner performance figures for sensitivity, q... | Watt | Wikipedia | 366 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
The kilowatt is typically used to express the output power of engines and the power of electric motors, tools, machines, and heaters. It is also a common unit used to express the electromagnetic power output of broadcast radio and television transmitters. One kilowatt is approximately equal to 1.34 horsepower. A small... | Watt | Wikipedia | 345 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
Gigawatt A gigawatt is typical average power for an industrial city of one million habitants, and is the output of a large power station. The GW unit is thus used for large power plants and power grids. For example, by the end of 2010, power shortages in China's Shanxi province were expected to increase to 5–6 GW and t... | Watt | Wikipedia | 479 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
Conventions in the electric power industry
In the electric power industry, megawatt electrical (MWe or MWe) refers by convention to the electric power produced by a generator, while megawatt thermal or thermal megawatt (MWt, MWt, or MWth, MWth) refers to thermal power produced by the plant. For example, the Embalse n... | Watt | Wikipedia | 467 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
Power stations are rated using units of power, typically megawatts or gigawatts (for example, the Three Gorges Dam in China is rated at approximately 22 gigawatts). This reflects the maximum power output it can achieve at any point in time. A power station's annual energy output, however, would be recorded using units ... | Watt | Wikipedia | 255 | 21347693 | https://en.wikipedia.org/wiki/Watt | Physical sciences | Energy, power, force and pressure | null |
Palaemon serratus, also called the common prawn, is a species of shrimp found in the Atlantic Ocean from Denmark to Mauritania, and in the Mediterranean Sea and Black Sea.
Ecology
Individuals live for 3–5 years in groups in rocky crevices at depths of up to . Females grow faster than males, and the population is highl... | Palaemon serratus | Wikipedia | 481 | 21349167 | https://en.wikipedia.org/wiki/Palaemon%20serratus | Biology and health sciences | Shrimps and prawns | Animals |
Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. What distinguishes them from other gases is that they absorb the wavelengths of radiation that a planet emits, resulting in the greenhouse effect. The Earth is warmed by sunlight, causing its surface... | Greenhouse gas | Wikipedia | 468 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
99% of the Earth's dry atmosphere (excluding water vapor) is made up of nitrogen () (78%) and oxygen () (21%). Because their molecules contain two atoms of the same element, they have no asymmetry in the distribution of their electrical charges, and so are almost totally unaffected by infrared thermal radiation, with o... | Greenhouse gas | Wikipedia | 486 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
Contributions of specific gases to the greenhouse effect
Anthropogenic changes to the natural greenhouse effect are sometimes referred to as the enhanced greenhouse effect.
This table shows the most important contributions to the overall greenhouse effect, without which the average temperature of Earth's surface wou... | Greenhouse gas | Wikipedia | 488 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
Many observations are available online in a variety of Atmospheric Chemistry Observational Databases. The table below shows the most influential long-lived, well-mixed greenhouse gases, along with their tropospheric concentrations and direct radiative forcings, as identified by the Intergovernmental Panel on Climate Ch... | Greenhouse gas | Wikipedia | 495 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
The proportion of an emission remaining in the atmosphere after a specified time is the "airborne fraction" (AF). The annual airborne fraction is the ratio of the atmospheric increase in a given year to that year's total emissions. The annual airborne fraction for had been stable at 0.45 for the past six decades even ... | Greenhouse gas | Wikipedia | 350 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
Changes to any of these variables can alter the atmospheric lifetime of a greenhouse gas. For instance, methane's atmospheric lifetime is estimated to have been lower in the 19th century than now, but to have been higher in the second half of the 20th century than after 2000. Carbon dioxide has an even more variable li... | Greenhouse gas | Wikipedia | 454 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
The natural flows of carbon between the atmosphere, ocean, terrestrial ecosystems, and sediments are fairly balanced; so carbon levels would be roughly stable without human influence. Carbon dioxide is removed from the atmosphere primarily through photosynthesis and enters the terrestrial and oceanic biospheres. Carbon... | Greenhouse gas | Wikipedia | 442 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
In the late 19th century, scientists experimentally discovered that and do not absorb infrared radiation (called, at that time, "dark radiation"), while water (both as true vapor and condensed in the form of microscopic droplets suspended in clouds) and and other poly-atomic gaseous molecules do absorb infrared radi... | Greenhouse gas | Wikipedia | 249 | 21350772 | https://en.wikipedia.org/wiki/Greenhouse%20gas | Physical sciences | Climate change | Earth science |
Tissue paper, or simply tissue, is a lightweight paper or light crêpe paper. Tissue can be made from recycled paper pulp on a paper machine.
Tissue paper is very versatile, and different kinds are made to best serve these purposes, which are hygienic tissue paper, facial tissues, paper towels, as packing material, amo... | Tissue paper | Wikipedia | 466 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
Facial tissue (paper handkerchiefs) refers to a class of soft, absorbent, disposable paper that is suitable for use on the face. The term is commonly used to refer to the type of facial tissue, usually sold in boxes, that is designed to facilitate the expulsion of nasal mucus although it may refer to other types of fac... | Tissue paper | Wikipedia | 479 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
Table napkins
Table napkins can be made of tissue paper. These are made from one up to four plies and in a variety of qualities, sizes, folds, colours and patterns depending on intended use and prevailing fashions. The composition of raw materials varies a lot from deinked to chemical pulp depending on quality.
Acoust... | Tissue paper | Wikipedia | 404 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
Packing industry
Apart from above, a range of speciality tissues are also manufactured to be used in the packing industry. These are used for wrapping/packing various items, cushioning fragile items, stuffing in shoes/bags etc. to keep shape intact or, for inserting in garments etc. while packing/folding to keep them w... | Tissue paper | Wikipedia | 445 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
Tissue paper production and consumption is predicted to continue to grow because of factors like urbanization, increasing disposable incomes and consumer spending. In 2015, the global market for tissue paper was growing at per annum rates between 8–9% (China, currently 40% of global market) and 2–3% (Europe).
During th... | Tissue paper | Wikipedia | 480 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
EDANA, the trade body for the non-woven absorbent hygiene products industry (which includes products such as household wipes for use in the home) has reported annually on the industry's environmental performance since 2005. Less than 1% of all commercial wood production ends up as wood pulp in absorbent hygiene product... | Tissue paper | Wikipedia | 450 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
The Confederation of European Paper Industries (CEPI) has published reports focusing on the industry's environmental credentials. In 2002, it noted that "a little over 60% of the pulp and paper produced in Europe comes from mills certified under one of the internationally recognised eco-management schemes". There are ... | Tissue paper | Wikipedia | 430 | 2026564 | https://en.wikipedia.org/wiki/Tissue%20paper | Technology | Materials | null |
Snakeflies are a group of predatory insects comprising the order Raphidioptera with two extant families: Raphidiidae and Inocelliidae, consisting of roughly 260 species. In the past, the group had a much wider distribution than it does now; snakeflies are found in temperate regions worldwide but are absent from the tro... | Snakefly | Wikipedia | 261 | 2026577 | https://en.wikipedia.org/wiki/Snakefly | Biology and health sciences | Insects: General | Animals |
Adult snakeflies are easily distinguished from similar insects by having an elongated prothorax but not the modified forelegs of the mantis-flies. Most species are between in length. The head is long and flattened, and heavily sclerotised; it may be broad or taper at the back, but is very mobile. The mouthparts are st... | Snakefly | Wikipedia | 492 | 2026577 | https://en.wikipedia.org/wiki/Snakefly | Biology and health sciences | Insects: General | Animals |
Snakeflies are holometabolous insects, having a four-stage life cycle with eggs, larvae, pupae and adults. Before mating, the adults engage in an elaborate courtship ritual, including a grooming behaviour involving legs and antennae. In raphidiids, mating takes place in a "dragging position", while in inocelliids, the ... | Snakefly | Wikipedia | 422 | 2026577 | https://en.wikipedia.org/wiki/Snakefly | Biology and health sciences | Insects: General | Animals |
Ecology
Adult snakeflies are territorial and carnivorous organisms. They are diurnal and are important predators of aphids and mites. Pollen has also been found in the guts of these organisms and it is unclear whether they require pollen for part of their lifecycle or if it is a favoured food source. The larvae of many... | Snakefly | Wikipedia | 499 | 2026577 | https://en.wikipedia.org/wiki/Snakefly | Biology and health sciences | Insects: General | Animals |
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