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8,031,252 | https://en.wikipedia.org/wiki/Osmotic-controlled%20release%20oral%20delivery%20system | The osmotic-controlled release oral delivery system (OROS) is an advanced controlled release oral drug delivery system in the form of a rigid tablet with a semi-permeable outer membrane and one or more small laser drilled holes in it. As the tablet passes through the body, water is absorbed through the semipermeable membrane via osmosis, and the resulting osmotic pressure is used to push the active drug through the laser drilled opening(s) in the tablet and into the gastrointestinal tract. OROS is a trademarked name owned by ALZA Corporation, which pioneered the use of osmotic pumps for oral drug delivery.
Rationale
Pros and cons
Osmotic release systems have a number of major advantages over other controlled-release mechanisms. They are significantly less affected by factors such as pH, food intake, GI motility, and differing intestinal environments. Using an osmotic pump to deliver drugs has additional inherent advantages regarding control over drug delivery rates. This allows for much more precise drug delivery over an extended period of time, which results in much more predictable pharmacokinetics. However, osmotic release systems are relatively complicated, somewhat difficult to manufacture, and may cause irritation or even blockage of the GI tract due to prolonged release of irritating drugs from the non-deformable tablet.
Oral osmotic release systems
Single-layer
The Elementary Osmotic Pump (EOP) was developed by ALZA in 1974, and was the first practical example of an osmotic pump based drug release system for oral use. It was introduced to the market in the early 1980s in Osmosin (indomethacin) and Acutrim (phenylpropanolamine), but unexpectedly severe issues with GI irritation and cases of GI perforation led to the withdrawal of Osmosin.
Merck & Co. later developed the Controlled-Porosity Osmotic Pump (CPOP) with the intention of addressing some of the issues that led to Osmosin's withdrawal via a new approach to the final stage of the release mechanism. Unlike the EOP, the CPOP had no pre-formed hole in the outer shell for the drug to be expelled out of. Instead, the CPOP's semipermeable membrane was designed to form numerous small pores upon contact with water through which the drug would be expelled via osmotic pressure. The pores were formed via the use of a pH insensitive leachable or dissolvable additive such as sorbitol.
Multi-layer
Both the EOP and CPOP were relatively simple designs, and were limited by their inability to deliver poorly soluble drugs. This led to the development of an additional internal "push layer" composed of material (a swellable polymer) that would expand as it absorbed water, which then pushed the drug layer (which incorporates a viscous polymer for suspension of poorly soluble drugs) out of the exit hole at a controlled rate. Osmotic agents such as sodium chloride, potassium chloride, or xylitol are added to both the drug and push layers to increase the osmotic pressure. The initial design developed in 1982 by ALZA researchers was designated the Push-Pull Osmotic Pump (PPOP), and Procardia XL (nifedipine) was one of the first drugs to utilize this PPOP design.
In the early 1990s, an ALZA-funded research program began to develop a new dosage form of methylphenidate for the treatment of children with attention deficit hyperactivity disorder (ADHD). Methylphenidate's short half-life required multiple doses to be administered each day to attain long-lasting coverage, which made it an ideal candidate for the OROS technology. Multiple candidate pharmacokinetic profiles were evaluated and tested in an attempt to determine the optimal way to deliver the drug, which was especially important given the puzzling failure of an existing extended-release formulation of methylphenidate (Ritalin SR) to act as expected. The zero-order (flat) release profile that the PPOP was optimal at delivering failed to maintain its efficacy over time, which suggested that acute tolerance to methylphenidate formed over the course of the day. This explained why Ritalin SR was inferior to twice-daily Ritalin IR, and led to the hypothesis that an ascending pattern of drug delivery was necessary to maintain clinical effect. Trials designed to test this hypothesis were successful, and ALZA subsequently developed a modified PPOP design that utilized an overcoat of methylphenidate designed to release immediately and rapidly raise serum levels, followed by 10 hours of first-order (ascending) drug delivery from the modified PPOP design. This design was called the Push-Stick Osmotic Pump (PSOP), and utilized two separate drug layers with different concentrations of methylphenidate in addition to the (now quite robust) push layer.
List of OROS medications
OROS medications include:
References
Pharmaceutical industry
Drug delivery devices
Dosage forms
Alza brands
Pharmacology
Pharmacokinetics | Osmotic-controlled release oral delivery system | Chemistry,Biology | 1,042 |
52,341,205 | https://en.wikipedia.org/wiki/Buridan%20formula | In quantified modal logic, the Buridan formula and the converse Buridan formula (more accurately, schemata rather than formulas) (i) syntactically state principles of interchange between quantifiers and modalities; (ii) semantically state a relation between domains of possible worlds. The formulas are named in honor of the medieval philosopher Jean Buridan by analogy with the Barcan formula and the converse Barcan formula introduced as axioms by Ruth Barcan Marcus.
The Buridan formula
The Buridan formula is:
.
In English, the schema reads: If possibly everything is F, then everything is possibly F. It is equivalent in a classical modal logic (but not necessarily in other formulations of modal logic) to
.
The converse Buridan formula
The converse Buridan formula is:
.
Buridan's logic
In medieval scholasticism, nominalists held that universals exist only subsequent to particular things or pragmatic circumstances, while realists followed Plato in asserting that universals exist independently of, and superior to, particular things.
References
See page 190.
Modal logic | Buridan formula | Mathematics | 235 |
3,464,584 | https://en.wikipedia.org/wiki/Visagie%27s%20golden%20mole | Visagie's golden mole (Chrysochloris visagiei) is a small, insectivorous mammal of the family Chrysochloridae, the golden moles, endemic to South Africa.
References
Endemic fauna of South Africa
Afrosoricida
Mammals of South Africa
Mammals described in 1950
Species known from a single specimen
Taxa named by Robert Broom | Visagie's golden mole | Biology | 74 |
2,839,480 | https://en.wikipedia.org/wiki/Martingale%20central%20limit%20theorem | In probability theory, the central limit theorem says that, under certain conditions, the sum of many independent identically-distributed random variables, when scaled appropriately, converges in distribution to a standard normal distribution. The martingale central limit theorem generalizes this result for random variables to martingales, which are stochastic processes where the change in the value of the process from time t to time t + 1 has expectation zero, even conditioned on previous outcomes.
Statement
Here is a simple version of the martingale central limit theorem: Let
be a martingale with bounded increments; that is, suppose
and
almost surely for some fixed bound k and all t. Also assume that almost surely.
Define
and let
Then
converges in distribution to the normal distribution with mean 0 and variance 1 as . More explicitly,
The sum of variances must diverge to infinity
The statement of the above result implicitly assumes the variances sum to infinity, so the following holds with probability 1:
This ensures that with probability 1:
This condition is violated, for example, by a martingale that is defined to be zero almost surely for all time.
Intuition on the result
The result can be intuitively understood by writing the ratio as a summation:
The first term on the right-hand-side asymptotically converges to zero, while the second term is qualitatively similar to the summation formula for the central limit theorem in the simpler case of i.i.d. random variables. While the terms in the above expression are not necessarily i.i.d., they are uncorrelated and have zero mean. Indeed:
References
Many other variants on the martingale central limit theorem can be found in:
Note, however, that the proof of Theorem 5.4 in Hall & Heyde contains an error. For further discussion, see
Martingale theory
Central limit theorem | Martingale central limit theorem | Mathematics | 387 |
7,494,699 | https://en.wikipedia.org/wiki/Workbench%20%28AmigaOS%29 | Workbench is the desktop environment and graphical file manager of AmigaOS developed by Commodore International for their Amiga line of computers. Workbench provides the user with a graphical interface to work with file systems and launch applications. It uses a workbench metaphor (in place of the more common desktop metaphor) for representing file system organisation.
"Workbench" was also the name originally given to the entire Amiga operating system up until version 3.1. From release 3.5 the operating system was renamed "AmigaOS" and subsequently "Workbench" refers to the native file manager only.
Overview
The Amiga Workbench uses the metaphor of a workbench (i.e. a workbench for manual labor), rather than the now-standard desktop metaphor, for representing file system organization. The desktop itself is called Workbench and uses the following representations: drawers (instead of folders) for directories, tools for executable programs, projects for data files, and a trash can as a folder intended to contain deleted files. These representations may be considered somewhat unusual by a modern user, but at the time there were no commonly accepted metaphors and Commodore chose to use different idioms from their competitors (Apple had already pursued legal action to prevent other software companies from offering graphical user interfaces similar to its own).
Workbench is a spatial file manager in the sense that it uses a spatial metaphor to represent files and folders as if they are real physical objects. Under this concept, each drawer (folder) opens in its own window, rather than within a single browser under the now more common navigational concept.
Workbench utilizes the Amiga's native windowing system called Intuition to provide the graphical user interface. Intuition manages the rendering of screens, windows, and gadgets (graphical elements, equivalent to widgets). Later versions of AmigaOS enhanced the interface with more complex object-oriented widget systems, such as gadtools.library and BOOPSI (AmigaOS 2.0 and later) and ReAction (AmigaOS 3.5 and later). Intuition also handles user input events, such as, input from the keyboard and mouse. Workbench requires a two button mouse, where right click operates pull-down menus and left click is used for all other purposes.
The underlying AmigaOS allows the Workbench to launch multiple applications that can execute concurrently. This is achieved through Exec, the Amiga's multi-tasking kernel, which handles memory management, message passing, and task scheduling. Applications launched from Workbench could report their success back to Workbench, but this was not a requirement and few actually did.
Workbench itself has always been a disk-based component, though much of the underlying functionality is stored in the Amiga's Kickstart firmware, usually stored in ROM. As a consequence, it is necessary to boot from a system disk to launch Workbench. This setup streamlines the process of launching games (which typically do not require Workbench) and ensures that memory is not used unnecessarily by the OS in memory-limited systems.
Workbench was shipped with all Amiga models from Commodore. Workbench was provided either on floppy disk or later (as part of AmigaOS) on CD-ROM. Initially, Workbench was designed to be launched and operate from floppy disk (or other removable media). Later versions could be installed on hard disk, for which an installer was developed for use with AmigaOS 2.0 and later. AmigaOS (including Workbench) often came pre-installed on systems shipped with hard disks.
Versions
Up until release 3.1 of the Amiga's operating system, Commodore used Workbench to refer to the entire Amiga operating system. As a consequence Workbench was commonly used to refer to both the operating system and the file manager component. For end users Workbench was often synonymous with AmigaOS. From version 3.5 the OS was renamed "AmigaOS" and pre-3.5 versions were also retroactively referred to as "AmigaOS" (rather than Workbench). Subsequently, "Workbench" refers to the native graphical file manager only.
From its inception, Workbench offered a highly customizable interface. The user could change the aspect of program icons replacing it with newer ones with different color combinations. Users could also take a "snapshot" of icons and windows so the icons will remain on the desktop at coordinates chosen by user and windows will open at the desired size.
Workbench 1.x
Workbench 1.0 was released with the first Amiga, the Amiga 1000, in 1985. The 1.x versions of Workbench used a blue-and-orange color scheme, designed to give high contrast on even the worst of television screens (the colors can be changed by the user). Versions 1.1 consists mostly of bug fixes and, like version 1.0, was distributed for the Amiga 1000 only.
The display was highly customizable for the era. The user was free to create and modify system and user icons, while Atari TOS featured only default system icons whose appearance could not be modified and customizing icons on the Macintosh required using ResEdit. Icons can be of arbitrary size and design and can have two image states to produce a pseudo-animated effect when selected. Users could customize four display colors and choose from two resolutions: or (interlaced) on NTSC, or or on PAL systems. In later revisions, the TV or monitor overscan could be adjusted.
Several features were deprecated in later versions. For example, the gauge meter showing the free space on a file system was replaced with a percentage in Workbench 2.0. Under Workbench 1.x, right clicking on icons opens a display of the files metadata, whereas from Workbench 2.0 right clicking activates pull-down menus only. The default "busy" pointer (a comic balloon showing "Zzz...") was replaced with a stopwatch in later versions.
Workbench 2.0, 2.1
Workbench 2.0 was released with the launch of the Amiga 3000 in 1990. Until AmigaOS 2.0 there was no unified look and feel design standard and application developers had to write their own widgets (both buttons and menus) if they wished to enhance the already-meager selection of standard basic widgets provided by Intuition. With Workbench 2.0 gadtools.library was created, which provided standard widget sets. The Amiga User Interface Style Guide, was published which explained how applications should be laid out for consistency. Intuition was improved with BOOPSI (Basic Object Oriented Programming system for Intuition) which enhanced the system with an object-oriented interface to define a system of classes in which every class individuate a single widget or describes an interface event. It can be used to program object oriented interfaces into Amiga at any level. As of Workbench 2.0 all files became visible as icons without the need of associated .info files, thus streamlining the process of starting executables in the GUI.
Workbench 2.0 also added support for public screens. Instead of the Workbench screen being the only shareable screen, applications could create their own named screens to share with other applications.
Workbench 2.0 included and integrated ARexx, allowing users to control the system and other programs from user scripts.
Workbench 2.0 introduced AmigaGuide, a simple text-only hypertext markup scheme and browser, for providing online help inside applications. It also introduced Installer, a standard software installation program, driven by a LISP-like scripting language.
Finally, Workbench 2.0 rectified the problem of applications hooking directly into the input-events stream to capture keyboard and mouse movements, sometimes locking up the whole system. Workbench 2.0 provided Commodities, a standard interface for modifying or scanning input events. This included a standard method for specifying global "hotkey" key-sequences, and a Commodities Exchange registry for the user to see which commodities were running.
Workbench 3.0, 3.1
Version 3.0 was originally shipped with the Amiga 1200 and Amiga 4000 computers. Version 3.0 added datatype support and Workbench could load any background image in any format, as long as the required datatype was installed. This feature was also used in Multiview. Its capabilities were directly related to the datatypes installed in Devs:Datatypes. Localisation was added to allow Workbench, and any installed programs that had localization, to appear in any supported language.
The established AmigaGuide hypertext system gained more usability by using document links pointing to mediafiles, for example pictures or sounds, all recognized by the datatypes.
Workbench 3.5, 3.9
Following Commodore's demise and around six years after Workbench 3.1 was released, Haage & Partner were commissioned to update AmigaOS, which was released in 1999 as a software-only update for existing m68k-systems with at least a 68020.
The Workbench look and feel, though still largely based on the earlier 3.1 release, was revised somewhat, with an improved user interface based on ReAction, improved icon rendering and official support for true color backdrops. These releases included support for existing third-party GUI enhancements, such as NewIcons, by integrating these patches into the system. The 3.5 and 3.9 releases included a new set of 256-color icons and a choice of desktop wallpaper. These replaced the default all-metal gray 4/8 color scheme used on AmigaOS from release 2.0 to 3.1.
The 3.9 release of Workbench was again developed by Haage&Partner and released in 2000. The main improvements were the introduction of a program start bar called AmiDock, revised user interfaces for system settings and improved utility programs.
Workbench 4.0, 4.1
This new Workbench, called Workbench 4.0, has been rewritten to become fully PowerPC compatible. It was part of AmigaOS 4.0, and released in 2006.
Since the fourth Developer Pre-Release Update screens are now draggable in any direction. Drag and drop of Workbench icons between different screens is also possible.
Additionally, Workbench 4.0 includes a new version of Amidock, TrueType/OpenType fonts and movie player with DivX and MPEG-4 support.
In AmigaOS 4.1, a new Startup preferences feature was added which replaced the WBStartup drawer. Additional enhancements include: a new icon set to complement higher screen resolutions, new window themes including drop shadows, AmiDock with true transparency, scalable icons, and a Workbench auto-update feature.
Workbench icons
The icons that Workbench uses to represent the files in a volume or a drawer are stored in special .info files, with the name of the .info file matching the name of the file it represents. For example, the icon for NotePad, a text editor, is found in the file NotePad.info. This .info extension is the only file extension required by AmigaOS.
The .info file contains the icon image and its spatial position within its parent window. The icon also specifies the type of the file, as used by Workbench. Workbench recognises five different file types:
Tool: An executable program.
Project: A data file of an executable program. The program which created the file is named in the icon file; double-clicking on the icon loads the program that created it.
Drawer: A directory containing files, and other drawers.
Volume: A physical disk or a RAM disk.
Garbage: The Trashcan – a deleted file backup, which works in a similar way to the 'Recycle bin' in Microsoft Windows.
An additional three file types are available and are intended for future expansion:
Device: designed for displaying information about attached devices.
Kick: The icon of a bootable disk.
App Icon: An icon which will be used as (part of) the GUI for an application.
Of these three file types, only "App Icons" currently are used by any part of Workbench/AmigaOS.
While an icon may represent or suggest a file type, the type of the related file is specified by its very own properties, along with the restrictions (AmigaDOS: protection flags) given to this file. For example, if you add a tool icon to a text document file, AmigaOS will tell you the file "is not executable" or "is not of required type" as it has no 'e'-protection-flag (AmigaDOS: Hold, Script, Pure, Archived, Read, Writeable, Executable, Deletable) nor does it have the startup header of an executable. Also, stripping an 'application' from its counterpart icon file (application.info) will not render this application useless; it still remains executable, it will run, only missing the (required) options and arguments delivered from workbench via icons "tool types", e.g. stack size, public screen, etc.
Starting in Workbench 2.x, a file without a .info counterpart (such as a file on non-native media) is represented by the default system icon for one of the five types listed above. These default icons are also customizable. Icon-less files are only displayed in this manner if the drawer is configured to [Show All Files] – if this option is not set (which is the case in Workbench 1.x), such files will not appear at all and can only be seen from a CLI.
Tool (application) files can include "tool types" in the .info file. These are used as configuration options for the program. Each tool type is a single line of text, which can optionally include parameters written after an = sign. Tool types can be commented out by writing them in parentheses. For example, the tooltype "CX_POPKEY=ctrl alt f1" defines that the application (a Commodity) will activate the user interface in response to the key sequence Ctrl-Alt-F1.
The colours used in the icon are normally only stored as indices to the Amiga Workbench screen's current palette. Because of this, the icons' colour scheme is inherently tied to the chosen hues in the screen's palette, and choosing non-standard colours can give the icons an ugly appearance. This problem was partly solved by a third-party system called NewIcons, which adds additional features to the standard .info files. Unlike normal Workbench icons, NewIcons include actual RGB colour information, and the system tries its best to match the icons' colour hues to those in the screen palette.
Since AmigaOS 3.5, Workbench supports icons with up to 256 colors. This release of AmigaOS features the GlowIcons icon set by Matt Chaput. With AmigaOS 3.5, a screen-palette-independent system is used. The 4.0 icons, designed by Martin Merz, can use a 24-bit palette.
Both AROS and MorphOS support PNG icons natively. PNG allows using full 24-bit palette with alpha blending. On Amiga Workbench PNG icons are supported through plugins.
Comparison to other file managers
In comparison to the competing Mac OS and Atari, the early Amiga Workbench (pre-Workbench 2.04) featured, as the default, a 4 color blue desktop screen with color icons at NTSC American standard or on European PAL television sets, in contrast to the black and white interface presented by the Mac. The Amiga user was also free to create and modify system and program icons, while Atari TOS featured only default system icons whose appearance could not be modified.
Workbench contributed many other unique features/philosophies to intuitive GUI design (starting with version 2.04/2.1):
Menu item indenting, which immediately indicated the item was a "toggle" function, eliminating guesswork for the user.
The concept of tri-level information using bevel shading to simulate a 3d appearance. Indented controls indicated information-only text, surface-level controls represented labels for GUI elements, and raised GUI elements indicated data editable by, or interactive with, the user.
Much like the "File" and "Edit" menus became standard on most GUIs, Workbench implemented the concept of a "Settings" menu designed to standardize the location for all options within an application.
Standardized buttons for OS-level preferences or settings dialog boxes through "Save", "Use", and "Cancel" provided a simple and consistent means for short- and long-term settings use.
Standardized preference settings for user-level import and export through a ".prefs" extension and file format.
Commodities Exchange: a consistent programming standard and GUI for easy launch, control, and removal of all TSRs or background-process utilities/mini-apps.
Datatypes: a modular and user-customizable data identification system that the OS used to recognize, launch, edit, and provide a means of importing and exporting data between OS and applications alike.
Locale: an OS and application-wide GUI that provided the means for implementing user-selectable language, time, and other locale-specific settings.
Criticisms
The freedom in customization and the multitude of color settings and aspects available to the user were sometimes seen as chaotic. Customization permitted icons of a vastly different size and appearance than those of the original system icons. Before Workbench 2.0, there were no user interface design guidelines, so the look and feel of menu options could be different from one application to the next (i.e. the layout of basic items like Load, Save, Open, Close, Quit, etc.). This was seen as a problem with the Amiga by its detractors. The historical GUI site GUIdebook calls Amiga Workbench a "unique (if slightly chaotic) GUI for Amiga machines".
Use in fictional media
The Ren'Py visual novel Digital: A Love Story uses an Amiga Workbench 1.0 design (known as Amie Workbench within the game).
See also
Ambient
Wanderer
Notes
Image included in this article it is intended for fair use. Neither Hyperion VOF (Belgium), nor Amiga Inc. (USA) have previously opposed publishing screenshots donated by users. Owners of Copyrights are free to register and write in the talk page of this article to ask for the removing of this image from article, and to ask also for its deletion from Wikipedia images.
References
External links
The Amiga Workbench Simulation
The Workbench Nostalgia Page
Amiga University – Amiga Workbench Replacements
All versions of Workbench explained on AmigaHistory site
In the Beginning Was CAOS, by Andy Finkel (updated version of 1988 Amiga Transactor article)
Name of the Amiga Operating System explained on Amiga Forever site
AmigaOS
Desktop environments
File managers
Graphical user interfaces
it:AmigaOS#Workbench | Workbench (AmigaOS) | Technology | 3,985 |
54,591,147 | https://en.wikipedia.org/wiki/Emanuel%20Gil-Av | Emanuel Gil-Av (Zimkin) (7 August 1916 – 24 March 1996) was an Israeli chemist. The main emphasis of his work constituted chiral chromatography for the analytical separation of enantiomers.
Life and Work
Emanuel Gil-Av was born 1916 in Pensa of Tzarist Russia. After the death of his father, a physician, the family moved first to Central Europe and in 1928 to Tel-Aviv, Israel, where Gil-Av attended High School. Gil-Av studied petroleum chemistry at the University of Strasbourg. In 1940 he escaped the German occupation to England where he worked at first in the chemical laboratory of Chaim Weizmann, followed by the Petrochemical Ltd. in Manchester. After World War II, he moved to Palestine and he joined the Daniel Sieff Institute in Rehovot which was later on to become the Weizmann Institute of Science. In 1951 he earned his PhD under the supervision of Ernst David Bergmann.
In his study of oil shale deposits, Gil-Av developed complex-forming stationary phases employing silver(I) ions for selective olefin separations by gas chromatography (GC). In co-operation with the centre of peptide chemistry at the Weizmann Institute of Science, he developed methods of the gas-chromatographic resolution of racemic α-amino acids. By coating a glass capillary column with the chiral stationary phase (CSP) N-trifluoroacetyl-L-isoleucine lauryl ester, Gil-Av et al. carried out in 1966 the first gas-chromatographic enantioseparation of racemic amino acids as N-trifluoroacetyl-O-alkyl derivatives. Many racemic compounds, amenable for enantioselective interaction via hydrogen bonding with the CSP, could be analytically enantioseparated by GC.
Further contributions of Gil-Av and associates are concerned with the use of chiral mobile phase additives (CMPAs) in liquid chromatography (LC), enantiomeric separation of helicenes by supramolecular LC, the temperature-dependent reversal of enantioselectivity by enthalpy-entropy compensation and non-linear effects leading to enantiomeric enrichment during chromatography on achiral stationary phases.
Literature
Emanuel Gil-Av, Present status of enantiomeric analysis by gas chromatography, J. Mol. Evol. 6 (1975) 131–144.
Nelu Grinberg: Emanuel Gil-Av (1916-1996): A man with a legacy, In: Chirality, 1998;10(5):372.
Volker Schurig: In Memoriam – Emanuel Gil-Av. In: Journal of High Resolution Chromatography 19 (1996) 462.
Volker Schurig: On the Centenary of Emanuel Gil-Av, Former Professor of the Weizmann Institute of Science and Pioneer of Enantioselective Chromatography, Isr. J. Chem. 56 (2016) 890–906.
References
1916 births
1996 deaths
People from Penza
People from Penzensky Uyezd
Jewish Russian scientists
Soviet emigrants to Mandatory Palestine
Analytical chemists
University of Strasbourg alumni
Academic staff of Weizmann Institute of Science | Emanuel Gil-Av | Chemistry | 701 |
2,308,428 | https://en.wikipedia.org/wiki/IC%201613 | IC 1613 (object 1613 in the Index Catalogues (IC), also known as Caldwell 51) is an irregular dwarf galaxy, visible in the constellation Cetus near the star 26 Ceti. It was discovered in 1906 by Max Wolf, and is approaching Earth at 234 km/s.
IC 1613 is a member of the Local Group. It has played an important role in the calibration of the Cepheid variable period-luminosity relation for estimating distances. Other than the Magellanic Clouds, it is one of the few Local Group dwarf irregular galaxy where RR Lyrae-type variables have been observed; this factor, along with an unusually low abundance of interstellar dust both within IC 1613 and along the line of sight enable especially accurate distance estimates.
In 1999, Cole et al. used the Hubble Space Telescope to find that the dominant population of this galaxy has an age of ~7 Gyr. Using its Hess diagram, they found that its evolutionary history may be similar to that of the Pegasus Dwarf Irregular Galaxy. Both galaxies are classified as Ir V in the DDO system. Also in 1999, Antonello et al. found five cepheids of Population II in IC 1613, giving self-evident support for the existence of a very old stellar population component of IC 1613. In 1999, King, Modjaz, & Li discovered the first nova ever detected in IC 1613.
IC 1613 contains a WO star known as DR1, which might be the only Wolf–Rayet star in the galaxy, although a candidate WC+O binary, SPIRITS14bqe, has been found. A Luminous Blue Variable candidate, has been proposed but a revised classification led to a B2.5 III type. Moreover, a rich population of OB-type stars and OB associations has been discovered.
There are many faint galaxies close to IC 1613, 14 of which are catalogued as members of a yet-unnamed galaxy cluster located at z≈0.20.
References
External links
Dwarf irregular galaxies
Local Group
Cetus
1613
00668
03844
051b
Astronomical objects discovered in 1906 | IC 1613 | Astronomy | 439 |
581,888 | https://en.wikipedia.org/wiki/Luminous%20flux | In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of electromagnetic radiation (including infrared, ultraviolet, and visible light), in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light.
Units
The SI unit of luminous flux is the lumen (lm). One lumen is defined as the luminous flux of light produced by a light source that emits one candela of luminous intensity over a solid angle of one steradian.
In other systems of units, luminous flux may have units of power.
Weighting
The luminous flux accounts for the sensitivity of the eye by weighting the power at each wavelength with the luminosity function, which represents the eye's response to different wavelengths. The luminous flux is a weighted sum of the power at all wavelengths in the visible band. Light outside the visible band does not contribute. The ratio of the total luminous flux to the radiant flux is called the luminous efficacy. This model of the human visual brightness perception, is standardized by the CIE and ISO.
Context
Luminous flux is often used as an objective measure of the useful light emitted by a light source, and is typically reported on the packaging for light bulbs, although it is not always prominent. Consumers commonly compare the luminous flux of different light bulbs since it provides an estimate of the apparent amount of light the bulb will produce, and a lightbulb with a higher ratio of luminous flux to consumed power is more efficient.
Luminous flux is not used to compare brightness, as this is a subjective perception which varies according to the distance from the light source and the angular spread of the light from the source.
Measurement
Luminous flux of artificial light sources is typically measured using an integrating sphere, or a goniophotometer outfitted with a photometer or a spectroradiometer.
Relationship to luminous intensity
Luminous flux (in lumens) is a measure of the total amount of light a lamp puts out. The luminous intensity (in candelas) is a measure of how bright the beam in a particular direction is. If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam, then the beam would have a luminous intensity of 1 candela. If the optics were changed to concentrate the beam into 1/2 steradian then the source would have a luminous intensity of 2 candela. The resulting beam is narrower and brighter, however the luminous flux remains the same.
Examples
References
Physical quantities
Photometry
Temporal rates | Luminous flux | Physics,Mathematics | 537 |
3,760,894 | https://en.wikipedia.org/wiki/Somewhere%20%28artist%20collective%29 | Somewhere is a multi-disciplinary UK-based creative organisation founded in 2001 by the artists and film-makers Karen Guthrie (born 1970) and Nina Pope (born 1968).
After studying together at Edinburgh College of Art, Pope and Guthrie completed MAs in London and began collaborating as artists in 1995, with their installation "Somewhere Over the TV" at the Collective Gallery in Edinburgh, followed by their live online travelogue "A Hypertext Journal" in March 1996.
Somewhere has long-term collaborators including the composer Tim Olden and the technologist Dorian Moore. In 2007, Guthrie and Pope won the first Northern Art Prize.
Works
The Floating Cinema
In 2010/11, Somewhere was appointed as guest artists to programme and create content for the Floating Cinema, part of Up Projects' Portavilion series of temporary cultural spaces for London. Housed in a customised narrowboat designed by the architects Studio Weave, the Floating Cinema was an Olympic Development Authority commission taking place across summer 2011 on the canals in the East End of London. Guest speakers and performers aboard included the Olympic polemicist Iain Sinclair, the broadcaster Michael Smith (who premiered his first film as director, Drift Street, aboard) and the nature writer Richard Mabey.
The project was recommissioned by the Legacy List (the charity leading the transformation of the former 2012 Olympic Park) to relaunch in 2013 with a new vessel designed by the London architects Duggan Morris.
Jaywick Escapes
The third feature documentary produced and directed by Guthrie and Pope was also shot by the directors, in 2010/11. This atmospheric and poignant film follows the stories of a handful of residents of the blighted seaside town of Jaywick in Essex, cited in government statistics as Britain's most deprived place. The film was premiered at the Sheffield Doc/Fest in summer 2012.
What Will the Harvest Be?
In 2008, Somewhere gained a major public commission from the London Borough of Newham to rejuvenate a barren site with Scheduled Ancient Monument Status close to the site of the 2012 Olympics in East London. The resulting proposal - What Will the Harvest Be? - became a major project to create an unregulated, publicly accessible harvest garden where anyone could grow and harvest vegetables and flowers. Working with an active residents' group, Friends of Abbey Gardens (FOAG), from spring 2009, the ruins of 19th-century housing and a medieval Cistercian gatehouse were stabilised and protected, and the plot was transformed with bespoke raised beds offering 1,000 linear metres of growing space. The garden design was influenced by historical research (e.g. the Plaistow Landgrabbers' Triangle Camp and the legacy of Cistercian gardens) and includes many specially designed elements which create a spectacular public space. What Will the Harvest Be? was initiated as a temporary site-specific project, and Somewhere also created a permanent design for the site. There are no plans to implement the permanent scheme. FOAG now manages the garden, holding diverse events for the community and visitors.
Living with the Tudors
The culmination of four years spent incognito within the UK historical re-enactment scene, "Living with the Tudors" is a documentary feature film shot entirely inside the 2007 Tudor (16th century) "re-creation" at Kentwell Hall in rural Suffolk. Among the 500 volunteers spending their summer holidays re-creating every aspect of 16th century English life, the film meets a core of loyal and protective re-enactors whose real-life stories form a fascinating counterpoint to their chosen Tudor roles. Shepherding through the thousands of paying visitors who keep Kentwell afloat is its owner, Patrick Phillips, a distantly paternal leader who describes the epic spectacles as his "game".
Bata-ville: We are not afraid of the future
In 2005, Somewhere co-produced Pope and Guthrie's first feature film, the unorthodox documentary travelogue Bata-ville: We are not afraid of the future, which was selected for the 2005 Edinburgh International Film Festival and has since become something of a cult success. The film follows a group of former Bata Shoes factory workers travelling from the UK to Zlín in the Czech Republic on a free coach trip hosted by the artists. The film sees them visit the origins of the global shoe empire built up by the early 20th century Czech entrepreneur Tomáš Baťa, in search of what his maxim "We are not afraid of the future" can mean in a changing Europe. The film originated in a commission by the agency Commissions East and the project has since become a benchmark for the contemporary public art genre. Bata-ville has been shown in many festivals and art venues, including at Tate Britain, SXSW Festival (Austin, Texas) 2006 and the Zlín Film Festival 2006.
TV swansong
In 2002, Somewhere produced the innovative media art project "TV swansong", the first live UK-based webcast of artists' projects commissioned specifically for the World-Wide Web, which took as its subject the demise of television in the age of convergent media. Featured artists were Graham Fagen, Jordan Baseman, Jessica Voorsanger, Zoe Walker and Neil Bromwich, Rory Hamilton and Jon Rogers, Chris Helson, Giorgio Sadotti.
/broadcast/ (29 pilgrims, 29 tales)
In 1999, Pope and Guthrie organised a contemporary version of Geoffrey Chaucer's The Canterbury Tales, which was 1999's Tate Modern (Bankside) Annual Event.
For this event, they chose 29 people to act as pilgrims and, on 11 September, they broadcast the pilgrims'stales live in Borough Market in Southwark, as well as webcasting them from this site onto the Internet. The website is now a record of the day's events, containing all the pilgrims' tales and prologues. The website contains an index, "The order of the day" and there a link to each pilgrim's home page, with details of the journeys they made to their chosen destinations within the project's 24-hour period.
The contributors tales were as follows: The Fisherman's Tale, The Poet's Tale, The Artist's Tale, Interlude, The Management Consultant's Tale, The Tarot Reader's Tale, The Parishioner's Tale, The Scientist's Tale, Interlude, The Van Driver's Tale, The Analysand's Tale, The Friend's Tale, The Punter's Tale, The Counsellor's Tale, The Nun's Tale, The Fiddle Maker's Tale, The Phototherapist's Tale, The Writer's Tale, Interlude, The Scholar's Tale, The Diver's Tale, The Environmental Manager's Tale, Interlude, The Passenger's Tale, The Shopper's Tale and The Dilettante's Tale.
At the end of the 24 hours, there was a feast when all the pilgrims met at Borough Market, ate and talked about their experiences.
Other works
Other works include:
The Festival of Lying, Grizedale Show, Cumbria, in collaboration with Anna Best and Simon Poulter (2000)
A Fair Place, British Council Group show, Nouvelles Peripheries, Istanbul, Turkey (2001)
Seven Samurai, site-specific project for the Echigo-Tsumari Triennale, Japan, curated by Grizedale Arts
Sometime Later, commissioned by the BBC and Arts Council England, a web/film project (2005/6)
Almanac, site-specific permanent commission for Cinema City in Norwich (2007)
References
External links
Somewhere's official site
Floating Cinema project site
What Will the Harvest Be? site
Living with the Tudors official film website
Broadcast (29 pilgrims, 29 tales) Tate Annual Event Borough Market – 11 September 1999, Tate Online press release (1999)
The Festival of Lying", Grizedale Show, Cumbria (2000)
Bata-ville: We are not afraid of the future:
somewhere.org.uk/bata-ville / Bata-ville official film website
Review of Bata-ville on BBC News
Review of Bata-ville on Variety.com
Review of Bata-ville on Telegraph.co.uk
Article about Bata-ville on Radio Praha
2001 establishments in the United Kingdom
British artist groups and collectives
Arts organisations based in the United Kingdom
New media
Somewhere | Somewhere (artist collective) | Technology | 1,704 |
35,326,250 | https://en.wikipedia.org/wiki/Glossary%20of%20classical%20algebraic%20geometry | The terminology of algebraic geometry changed drastically during the twentieth century, with the introduction of the general methods, initiated by David Hilbert and the Italian school of algebraic geometry in the beginning of the century, and later formalized by André Weil, Jean-Pierre Serre and Alexander Grothendieck. Much of the classical terminology, mainly based on case study, was simply abandoned, with the result that books and papers written before this time can be hard to read. This article lists some of this classical terminology, and describes some of the changes in conventions.
translates many of the classical terms in algebraic geometry into scheme-theoretic terminology. Other books defining some of the classical terminology include , , , , , .
Conventions
The change in terminology from around 1948 to 1960 is not the only difficulty in understanding classical algebraic geometry. There was also a lot of background knowledge and assumptions, much of which has now changed. This section lists some of these changes.
In classical algebraic geometry, adjectives were often used as nouns: for example, "quartic" could also be short for "quartic curve" or "quartic surface".
In classical algebraic geometry, all curves, surfaces, varieties, and so on came with fixed embeddings into projective space, whereas in scheme theory they are more often considered as abstract varieties. For example, a Veronese surface was not just a copy of the projective plane, but a copy of the projective plane together with an embedding into projective 5-space.
Varieties were often considered only up to birational isomorphism, whereas in scheme theory they are usually considered up to biregular isomorphism.
Until circa 1950, many of the proofs in classical algebraic geometry were incomplete (or occasionally just wrong). In particular authors often did not bother to check degenerate cases.
Words (such as azygetic or bifid) were sometimes formed from Latin or Greek roots without further explanation, assuming that readers would use their classical education to figure out the meaning.
Definitions in classical algebraic geometry were often somewhat vague, and it is futile to try to find the precise meaning of some of the older terms because many of them never had a precise meaning. In practice this did not matter much when the terms were only used to describe particular examples, as in these cases their meaning was usually clear: for example, it was obvious what the 16 tropes of a Kummer surface were, even if "trope" was not precisely defined in general.
Algebraic geometry was often implicitly done over the complex numbers (or sometimes the real numbers).
Readers were often assumed to know classical (or synthetic) projective geometry, and in particular to have a thorough knowledge of conics, and authors would use terminology from this area without further explanation.
Several terms, such as "Abelian group", "complete", "complex", "flat", "harmonic", "homology", "monoid", "normal", "pole", "regular", now have meanings that are unrelated to their original meanings. Other terms, such as "circle", have their meanings tacitly changed to work in complex projective space; for example, a circle in complex algebraic geometry is a conic passing through the circular points at infinity and has underlying topological space a 2-sphere rather than a 1-sphere.
Sometimes capital letters are tacitly understood to stand for points, and small letters for lines or curves.
Symbols
A
B
C
D
E
env
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
XYZ
See also
Glossary of algebraic geometry
Glossary of arithmetic and Diophantine geometry
Glossary of commutative algebra
Glossary of differential geometry and topology
Glossary of invariant theory
Glossary of Riemannian and metric geometry
Glossary of scheme theory
List of complex and algebraic surfaces
List of surfaces
List of curves
References
History of geometry
Geometry
Wikipedia glossaries using description lists | Glossary of classical algebraic geometry | Mathematics | 809 |
30,831,159 | https://en.wikipedia.org/wiki/Winston%20cone | A Winston cone is a non-imaging light collector in the shape of an off-axis parabola of revolution with a reflective inner surface. It concentrates the light passing through a relatively large entrance aperture through a smaller exit aperture. The collection of incoming rays is maximized by allowing off-axis rays to make multiple reflections before reaching the exit aperture. Winston cones are used to concentrate light from a large area onto a smaller photodetector or photomultiplier. They are widely used for measurements in the far infrared portion of the electromagnetic spectrum in part because there are no suitable materials to form lenses in the range.
Winston cones take their name from their inventor, the physicist Roland Winston. It is commercialized by companies such as Winston Cone Optics
References
See also
Nonimaging optics
Optical devices
Nonimaging optics | Winston cone | Materials_science,Engineering | 165 |
33,661,741 | https://en.wikipedia.org/wiki/Heart%20nanotechnology | Heart nanotechnology is the "Engineering of functional systems at the molecular scale" ("Nanotechnology Research").
Nanotechnology
Nanotechnology deals with structures and materials that are approximately one to one-hundred nanometers in length. At this microscopic level, quantum mechanics take place and are in effect, resulting in behaviors that would seem quite strange compared to what humans see with the naked eye (regular matter). Nanotechnology is used for a wide variety of fields of technology, ranging from energy to electronics to medicine. In the category of medicine, nanotechnology is still relatively new and has not yet been widely adopted by the field. It is possible that nanotechnology could be the new breakthrough of medicine and may eventually be the solution and cure for many of the health problems that humans encounter. Nanotechnology may lead to the cure for illnesses such as the common cold, diseases, and cancer. It is already starting to be used as a treatment for some serious health issues; more specifically it is being used to treat the heart and cancer.
Nanomedicine
Nanotechnology in the field of medicine is more commonly referred to as nanomedicine. Nanomedicine that deals with helping the heart is really starting to take off and gain in popularity compared to most of the other fields that nanomedicine currently has to offer. There are several heart problems that nanotechnology has promising evidence of being effective in the treatment of heart disease in the near future.
Examples
It should hopefully be able to treat heart valves that are defective; and detect and treat arterial plaque in the heart ("Nanotechnology Made Clear"). Nanomedicine should be able to help heal the hearts of people that have already been victims of heart disease and heart attacks. On the other hand, it will also play a key role in finding people with a high risk of having heart disease, and will be able to help prevent heart attacks from happening in the first place. Nanotechnology of the heart is a lot less invasive than surgery because everything is occurring at a minuscule level in the body compared to relatively large tissues that are dealt with in surgery. With our technology today, heart surgeries are performed to treat the damaged heart tissue that resulted from a heart attack. This is a major surgery that usually takes a couple of months to recover from ("WebMD - Better Information. Better Health"). During this period, patients are extremely limited in the activities that they can do. This long recovery process is an inconvenience to the patients, and with the growth of medicine it most likely won't be very long before a more efficient method for treating heart attack patients will be developed and used. The method that is the frontrunner to replace major heart surgery is the use of nanotechnology. There are a couple alternate ways to heart surgery that nanotechnology will potentially be able to offer in the future.
Alternatives to surgery
With people that have heart disease or that have suffered a heart attack, their hearts are often damaged and weakened. The more minor forms of heart failure do not require surgery and are often treated with medications ("WebMD - Better Information. Better Health"). The use of nanotechnology on treating damaged hearts will not replace these milder heart problems, but rather the more serious heart problems that currently require surgery or sometimes even heart transplants.
Heart repair
A group of engineers, doctors and materials scientists at MIT and Children's Hospital Boston have teamed together and are starting the movement of finding a way to use nanotechnology to strengthen the weakened heart tissue ("MIT - Massachusetts Institute of Technology"). The first method uses nanotechnology combined with tissue engineering, and gold nanowires are placed and woven into the damaged parts of the heart, essentially replacing the non-functioning or dead tissues.
Tissue regeneration
The other approach would potentially use minuscule nanoparticles that would travel through the body and find dying heart tissue. The nanoparticles would be carrying objects such as "stem cells, growth factors, drugs and other therapeutic compounds,". Then the nanoparticles would release the compounds and inject them into the damaged heart tissue. This would theoretically lead to the regeneration of the tissue.
Heart repair difficulties
Being able to fix cardiac tissue that has been damaged from a heart attack or heart disease is not very simple and it is one of the major challenges today in the field of tissue engineering ("Popular Science"). This is because heart cells are not the easiest objects to create in a lab. It takes an enormous amount of special care and work to develop the cells so that they beat in sync with one another ("Popular Science"). Even after the heart cells have finally been made, it is also a large task to insert the cells into the inoperable parts of the heart and to get them working in unison with the tissues that were still working properly ("Popular Science").
Heart patches
There have been several successful examples of this with the use of a "stem-cell- based heart patch developed by Duke University researchers," ("Popular Science"). The biomaterials that make up the patch are usually made of either biological polymers like alginate or synthetic polymers such as polylactic acid ("Nature Nanotechnology"). These materials are good at organizing the cells into functioning tissues; however they act as insulators and are poor conductors of electricity, which is a major problem especially in the heart ("Nature Nanotechnology"). Since the electrical signals that are sent between calcium ions are what control when the cardiomyocytes of the heart contract, which makes the heart beat, the stem-cell heart patch is not very efficient and not as effective as doctors would like it to be ("Popular Science"). The results of the patch not being very conductive is that the cells are not able to attain a smooth, continuous beat throughout the entire tissue containing the stem cells. This results in the heart not functioning properly, which in turn could mean that more heart problems might arise due to the implanting of the stem cells.
Tissue scaffolds
Recently there have been some new developments in the field of nanotechnology that will be more efficient than the poorly conducting stem-cell-based patch ("Nature Nanotechnology"). Scientists and researchers found a way for these stem cell patches (also known as tissue scaffolds) to be conductive and therefore become exponentially more effective ("Nature Nanotechnology"). They found that by growing gold nanowires into and through the patches, they were able to greatly increase the electrical conductivity. The nanowires are thicker than the original scaffold and the cells are better organized as well. There is also an increase in production of the proteins needed for muscle calcium binding and contraction. The gold nanowires poke through the stem cell's scaffolding material, which strengthens the electrical communication between surrounding heart cells. Without the nanowires, the stem cell patches produced a minute current and the cells would only beat in small clusters at the stimulation origin. With the nanowires, the cells seem to contract together even when they are clustered far away from the source of stimulation. The use of gold nanowires with the stem cell heart patches is still a relatively new concept and it will probably be awhile before they will be used in humans. It is hoped that the nanowires will be tested in live animals in the near future.
Nanoparticles
Another way that nanotechnology will potentially be used to help fix damaged heart tissues is through the use of guided nanoparticle "missiles". These nanoparticles can cling to and attach to artery walls and secrete medicine at a slow rate ("MIT-Massachusetts Institute of Technology"). The particles, known as nanoburrs due to the fact that they are coated with little protein fragments that stick to and target certain proteins. The nanoburrs can be made to release the drug that is attached to them over the course of several days ("MIT-Massachusetts Institute of Technology"). They are unique compared to regular drugs because they can find the particular damaged tissue, attach to it, and release the drug payload that is attached to it ("MIT-Massachusetts Institute of Technology"). What happens is the nanoburrs are targeted to a certain structure, known as the basement membrane; this membrane lines the arterial walls and is only present if the area is damaged. Nanoburrs could be able to carry drugs that are effective in treating the heart, and also potentially carry stem cells to help regenerate the damaged heart tissue ("MIT-Massachusetts Institute of Technology").
Composition
The particles are made up of three different layers and are sixty nanometers in diameter ("MIT-Massachusetts Institute of Technology").The outer layer is a coating of polymer called PEG, and its job is to protect the drug from disintegrating while it is traveling through the body. The middle layer consists of a fatty substance and the inner core contains the actual drug along with a polymer chain, which controls the amount of time it will take before the drug is released ("MIT-Massachusetts Institute of Technology").
Research
In a study done on rats, the nanoparticles were injected directly into the rat's tail and they still were able to reach the desired target (the left carotid artery) at a rate that was twice the amount of the non-targeted nanoparticles ("MIT-Massachusetts Institute of Technology"). Because the particles can deliver drugs over a long period of time, and can be injected intravenously, the patients would not need to have multiple repeated injections, or invasive surgeries on the heart which would be a lot more convenient. The only downside to this is that the existing delivery approaches are invasive, requiring either a direct injection into the heart, catheter procedures, or surgical implants. There is no question, however, that the future of heart repairs and heart disease/attack prevention will definitely involve the use of nanotechnology in some way.
Polyketal nanoparticles
Composition
Polyketal nanoparticles are pH-sensitive, hydrophobic nanoparticles formulated from poly(1-4-phenyleneacetone dimethylene ketal). They are an acid-sensitive vehicle of drug delivery, specifically designed for targeting the environments of tumors, phagosomes, and inflammatory tissue. In such acidic environments, these nanoparticles undergo accelerated hydrolysis into low molecular weight hydrophilic compounds, consequently releasing their therapeutic contents at a faster rate. Unlike polyester-based nanoparticles, polyketal nanoparticles do not generate acidic degradation products following hydrolysis
Use in myocardial infarction
Post-myocardial infarction, inflammatory leukocytes invade the myocardium. Leukocytes contain high amounts of Nicotinamide adenine dinucleotide phosphate (NADPH) and Nox2. Nox2 and NADPH oxidase combine to act as a major source of cardiac superoxide production, which in excess can lead to myocyte hypertrophy, apoptosis, fibrosis, and increased matrix metalloproteinase-2 expression. In a mouse-model study by Somasuntharam et al. 2013, polyketal nanoparticles were used as a delivery vehicle for siRNA to target and inhibit Nox2 in the infarcted heart. Following intramyocardial injection in vivo, Nox2-siRNA nanoparticles prevented upregulation of Nox2-NADPH oxidase, and improved fractional shortening. When taken up by macrophages in the myocardium following a MI, the nanoparticles degraded in the acidic environment of the endosomes/phagosomes, releasing Nox2-specific siRNA into the cytoplasm.
Polyketal nanoparticles have also been used in the infarcted mouse heart to prevent ischemia-reperfusion injury caused by reactive oxygen species (ROS). Levels of the antioxidant Cu/Zn-superoxide dismutase (SOD1), which scavenges harmful ROS, decrease following MI. SOD1-enacapsulated polyketal nanoparticles are able to scavenge reperfusion-injury induced ROS. Furthermore, this treatment improved fractional shortening, suggesting the benefit of targeted delivery by polyketals. One of the key advantages of polyketal use is that they do not exacerbate the inflammatory response, even when administered at concentrations exceeding therapeutic limits. In contrast to commonly used poly(lactic-co-glycolic acid) (PLGA) nanoparticles, polyketal nanoparticle administration in mice instigates little recruitment of inflammatory cells. Additionally, intramuscular injection of polyketals into the leg of rats shows no significant increases in inflammatory cytokines such as IL-6, IL-1ß, TNF-α and IL-12.
References
Additional reading
Heart
Medical technology
Nanomedicine
Biotechnology | Heart nanotechnology | Materials_science,Biology | 2,716 |
77,230,506 | https://en.wikipedia.org/wiki/Vojin%20G.%20Oklobdzija | Vojin G. Oklobdzija (Cyrillic: Војин Г. Оклобџија) is a computer and electronics engineer, scientist, author, and academic. He is professor emeritus of the University of California, Life Fellow of IEEE and past President of the IEEE Circuits and Systems Society.
Education
Oklobdzija obtained his Dipl. Ing. in electronics and telecommunications from the University of Belgrade, Yugoslavia in 1971, and subsequently worked as a research physicist in plasma physics pursuing his graduate degree. He became a Faculty Member in the Electrical Engineering Department there in 1974 serving until 1976. Later, he earned his MSc in 1978 and PhD in Computer Science in 1982 from the University of California Los Angeles. While pursuing his doctorate, he worked at the Microelectronics Division of Xerox Corporation until 1982, where he was involved in chip development for the early Alto workstation. He holds the highest USA Ham-Radio category, Extra, and call sign WF1A.
Career
From 1982 to 1991 Oklobdzija was a research staff member at the IBM Thomas J. Watson Research Center, where he contributed to the development of RISC processors, super-scalar, and supercomputer designs. He obtained several patents on early RISC machine organization, including one on register-renaming, which he co-holds with John Cocke and Greg Grohoski. This patent described a key feature of the IBM RS/6000.
In 1988 Oklobdzija started his academic career as a Visiting Faculty Member at the University of California, Berkeley, transitioning from his role at IBM. He later served as a Chair Professor in Electrical and Computer Engineering at Sydney University in Australia. Receiving Fulbright Professorships twice, in Peru in 1990 and Argentina in 2012, he helped establish internet connectivity in Peru in 1991 and developed academic courses in Computer Engineering. He has provided expert witness services, testifying at the International Trade Commission Court and in civil court.
At Siemens, which later became Infineon, he served as a Principal Architect and patent holder for the Infineon TriCore processor, an automotive control processor used in vehicles. He also contributed to the original conceptual development of the PlayStation at Sony.
Research
Oklobdzija's work focuses on VLSI chip engineering: low-power digital circuits optimizing the energy-speed relationship, machine learning, computer arithmetic, media signal processing, and system architecture; he has obtained 25 U.S. patents throughout his career.
Personal life
His son is social scientist Stan N. Oklobdzija.
Awards and honors
1971–1973 – National Science Fellowship on Plasma Physics, National Science Foundation
1976 – Fulbright Scholarship to USA, Fulbright Program
1985 – Patent Award, IBM
1985 – Invention Plateau Award, IBM
1991 – Fulbright Professorship to Peru, Fulbright Program
1995 – Fellow, Institute of Electrical and Electronics Engineers
2000–2003 – Distinguished Lecturer, IEEE Circuits and Systems Society
2000–2007 – Distinguished Lecturer, IEEE Solid-State Circuits Society
2002 – Outstanding Academic Title for The Computer Engineering Handbook, Choice Magazine
2012 – Fulbright Professorship to Argentina, Fulbright Program
2014 – Life Fellow, Institute of Electrical and Electronics Engineers
Bibliography
Selected books
Computer Engineering: Digital Systems and Applications 1st Edition (1997) ISBN 978-0849386190
Computer Engineering: Digital Design and Fabrication 1st Edition (1997) ISBN 978-0849386022
High-Performance System Design: Circuits and Logic 1st Edition (1999) ISBN 978-0780347168
The Computer Engineering Handbook 1st Edition (2001) ISBN 978-0849308857
Digital System Clocking: High-Performance and Low-Power Aspects 1st Edition (2003) ISBN 978-0471274476
High-Performance Energy-Efficient Microprocessor Design 1st Edition (2006) ISBN 978-3540679097
The Computer Engineering Handbook 2nd Edition (2008) ISBN 978-0849386008
Selected articles
Oklobdzija, V. G. (1994). An algorithmic and novel design of a leading zero detector circuit: Comparison with logic synthesis. IEEE Transactions on Very Large Scale Integration (VLSI) Systems, 2(1), 124–128.
Oklobdzija, V. G., Maksimovic, D., & Lin, F. (1997). Pass-transistor adiabatic logic using single power-clock supply. IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, 44(10), 842–846.
Oklobdzija, V. G., Villeger, D., & Liu, S. S. (1996). A method for speed optimized partial product reduction and generation of fast parallel multipliers using an algorithmic approach. IEEE Transactions on computers, 45(3), 294–306.
Stojanovic, V., & Oklobdzija, V. G. (1999). Comparative analysis of master-slave latches and flip-flops for high-performance and low-power systems. IEEE Journal of solid-state circuits, 34(4), 536–548.
Nikolic, B., Oklobdzija, V. G., Stojanovic, V., Jia, W., Chiu, J. K. S., & Leung, M. M. T. (2000). Improved sense-amplifier-based flip-flop: Design and measurements. IEEE Journal of Solid-State Circuits, 35(6), 876–884.
References
Computer scientists
Electronics engineers
Yugoslav academics
University of California, Berkeley faculty
University of California, Davis faculty
Academic staff of the University of Sydney
Academic staff of the École Polytechnique Fédérale de Lausanne
University of Belgrade alumni
University of California, Los Angeles alumni
Yugoslav writers
Living people
Year of birth missing (living people) | Vojin G. Oklobdzija | Technology,Engineering | 1,211 |
47,700,081 | https://en.wikipedia.org/wiki/Sony%20Xperia%20Z5 | The Sony Xperia Z5 is an Android smartphone produced by Sony. Part of the Sony Xperia Z series, the device, at that point known by the project code name "Sumire", was unveiled along with the Xperia Z5 Compact and Xperia Z5 Premium during a press conference at IFA 2015 on September 2, 2015. The device was launched globally in October and was launched in the United States as an unlocked device in February 2016. It is the successor to the Sony Xperia Z3+.
Similar to its predecessor, the device is water and dust proof with an IP rating of 65 and 68. It is Sony's first device to feature a fingerprint sensor. The device comes with 23 Megapixel camera with 0.03 seconds Hybrid Autofocus that utilizes phase detection autofocus, similarly found in the Xperia M5.
In February 2016, it was confirmed by Sony Mobile's senior product marketing manager Jun Makino that the Sony Xperia Z5 will be the final smartphone in the Sony Xperia Z series, with all future releases being released as part of the Sony Xperia X series. However this rumor was dismissed as Sony's Head of Marketing, Don Mesa has clarified that the X Series will not replace the Z Series.
Specifications
Hardware
Unlike its predecessors, the Xperia Z5's body design consists of an aluminium frame with a frosted glass backing to reduce fingerprints appearing on the back of the phone. The device carries an IP rating of IP65 and IP68, making it dust and water resistant. The device features a (marketed as 5.2-in) 1080p display with a density of 424 ppi, featuring Sony's "Triluminos" technology. The device also features a 64-bit 2.0 GHz octa-core Qualcomm Snapdragon 810 system-on-chip with 3 GB of RAM. The device also has 32 GB internal storage with microSD card expansion up to 200 GB. The device also includes a non-removable 2900 mAh battery.
The rear-facing camera of the Xperia Z5 is 23 megapixels with sensor size of 1/2.3 inch and an aperture of f/2.0, featuring a newer Sony Exmor RS image sensor, instead of the 20.7 megapixels image sensor which was used in all of its predecessors, starting from the Xperia Z1. Similarly found in the Xperia M5, the devices also features hybrid autofocus that utilizes phase detection autofocus that can focus the object within 0.03 seconds.
Xperia Z5 also features a redesigned power button located on the right side of the device with a fingerprint recognition system which can be used to unlock the phone. However, the fingerprint sensor is disabled in the US version of the phone due to a "business decision", although it can be reenabled by modifying the firmware.
Software
The Xperia Z5 is preinstalled with Android 5.1 Lollipop with Sony's custom interface and software. Pre-loaded applications on the Z5 provide access to Google's various services, including Google Play, which can be used to download and purchase apps, music, movies, and e-books.
On first week of March 2016, Sony released the Android 6.0 Marshmallow software update for the Xperia Z5.
On August 23, 2016, Sony announced that the Xperia Z5 would receive an upgrade to Android 7.0 Nougat. The update started rolling out in January 2017, but was put on hold shortly thereafter upon "reports from some users experiencing inconsistencies related to audio playback via third-party apps and SD card encrypted data read performance." The update re-commenced in February 2017.
See also
Sony Xperia Z5 Compact
Sony Xperia Z5 Premium
References
External links
Official Press Release
Official Whitepaper
Official Whitepaper (Dual SIM version)
For Full Information About This Mobile
Android (operating system) devices
Discontinued flagship smartphones
Sony smartphones
Mobile phones introduced in 2015
Digital audio players
Mobile phones with 4K video recording | Sony Xperia Z5 | Technology | 851 |
2,612,804 | https://en.wikipedia.org/wiki/Electron%20bubble | An electron bubble is the empty space created around a free electron in a cryogenic gas or liquid, such as neon or helium. They are typically very small, about 2 nm in diameter at atmospheric pressure.
Electron bubbles in helium
At room temperature, electrons in noble gasses move about freely, limited only by collisions with the weakly interacting atoms. Their mobility, which depends on the gas density and temperature, is well described by classical kinetic theory. As the temperature is lowered, the electron mobility decreases, since the helium atoms slow down at lower temperature and do not interact with the electron as often.
Below a critical temperature, the mobility of the electrons drops quickly to a value much below what is expected classically. This discrepancy led to the development of the electron bubble theory. At low temperatures, electrons injected into liquid helium do not move freely as one might expect, but rather form small vacuum bubbles around themselves.
Electron repulsion from the surface of helium
Electrons are attracted to liquid helium due to the difference in dielectric constants between the gas and liquid phase of helium. The negative electron polarizes the helium at the surface, leading to an image charge which binds it to the surface. The electron is forbidden from entering the liquid for the same reason hydrogen atoms are stable: quantum mechanics. The electron and image charge form a bound state, just as an electron and proton do in a hydrogen atom, with a minimum average separation. In this case, the minimum energy is about 1 eV (a moderate amount of energy on an atomic scale)[3].
When an electron is forced into liquid helium rather than floating on its surface, it forms a bubble rather than entering the liquid. The size of this bubble is determined by three main factors (ignoring small corrections): the confinement term, the surface tension term, and the pressure-volume term. The confinement term is purely quantum mechanical, since whenever an electron is tightly confined, its kinetic energy goes up. The surface tension term represents the surface energy of the liquid helium; this is exactly like water and all other liquids. The pressure-volume term is the amount of energy needed to push the helium out of the bubble.[4]
Here E is the energy of the bubble, h is the Planck constant, m is the electron mass, R is the bubble radius, α is the surface energy, and P is the ambient pressure.
2S electron bubble
A theoretical prediction has been made based on the analysis of the equation above,[5] that the 2S electron bubble exhibits a startling morphological instability under a wide range of ambient pressures. While its wave function is spherical, the stable shape of the bubble is nonspherical.
References
Footnotes
1.
2.
3.
4.
5.
External links
Electron
Cryogenics | Electron bubble | Physics,Chemistry | 560 |
27,883,731 | https://en.wikipedia.org/wiki/Motorola%20i58sr | The Motorola i58sr is a candybar style cell phone manufactured by Motorola. It was released in 2002. It has a grayscale screen. The phone was used by Nextel and SouthernLINC.
References
i58sr | Motorola i58sr | Technology | 48 |
43,229,668 | https://en.wikipedia.org/wiki/Rebecca%20M.%20Bergman | Rebecca M. Bergman is an American chemical engineer and the 17th President of Gustavus Adolphus College in St. Peter, Minnesota. She began her term in July 2014, and is the first woman to serve as President of the college, which was founded in 1862. Before her presidency, she was a senior executive at Medtronic, and served on the college's Board of Trustees from 2007 to 2014.
Medtronic career
Bergman received a B.S. in chemical engineering from Princeton University, and undertook graduate studies in chemical engineering and material science from the University of Minnesota.
Bergman spent 26 years at Medtronic, Inc., from 1988 to 2014, including 14 as a senior executive. Her most recent position was Vice President of Research, Technology, and Therapy Delivery Systems for the company’s Cardiac Rhythm Disease Management (CRDM) business, where she led a research and development team of scientists and engineers. She previously served as Vice President, CRDM New Therapies & Diagnostics as well as Vice President, Corporate Science and Technology, where she directed biomaterials and biosciences R&D, new therapy development, and information management initiatives.
Honors and Distinctions
Bergman was elected as a Fellow of the American Institute for Medical and Biological Engineering in 2001. She was also elected as a member into the National Academy of Engineering in 2010 for technical leadership in the development of interventional vascular devices and drug delivery systems.
She serves as a member of the Board of Directors of Sigma-Aldrich, on the Board of Directors of The Bakken Museum, and on a number of academic advisory boards. She previously served on the National Advisory Council of the National Institute of Biomedical Imaging and Bioengineering of the National Institute of Health and the St. Catherine University Board of Trustees.
References
Living people
Heads of universities and colleges in the United States
Princeton University alumni
University of Minnesota alumni
Fellows of the American Institute for Medical and Biological Engineering
Year of birth missing (living people)
Women heads of universities and colleges
21st-century American women academics
21st-century American academics
21st-century American women engineers
Women chemical engineers
Gustavus Adolphus College faculty
Presidents of Gustavus Adolphus College
Engineers from Minnesota | Rebecca M. Bergman | Chemistry | 441 |
53,950,481 | https://en.wikipedia.org/wiki/IStreamPlanet | iStreamPlanet was a Seattle, Washington-based company that processes and delivers live video broadcasts over the internet. A majority stake of iStreamPlanet was acquired by Turner Broadcasting in 2015 and was lastly operated by Warner Bros. Discovery. The company was founded in 2000 by former basketball player Mio Babic.
iStreamPlanet streamed a number of major sporting events, including NCAA Division I men's basketball tournaments, the Olympics, the Super Bowl, the FIFA World Cup, and Formula One auto racing.
iStreamPlanet was formally shutdown in 2023 with 25 employees laid off. Months before this, external companies had been told that iStreamPlanet was changing models to no longer have external customers outside of Warner Bros. Discovery.
Customers
While not all of iStreamPlanet's live video streaming customers were publicly known, some of their large customers are publicly acknowledged, including:
WarnerMedia (including streaming of March Madness and B/R Live)
NBC Sports (including streaming of the 2010, 2012, 2014, 2016, 2018, 2020, and 2022 Olympics)
Hulu
FuboTV
Spark Sport
References
External links
Online mass media companies of the United States
2000 software
Former Warner Bros. Discovery subsidiaries
Streaming software
Streaming media systems
Media servers
Former AT&T subsidiaries | IStreamPlanet | Technology | 264 |
63,579,017 | https://en.wikipedia.org/wiki/Jack%20Ma%20Foundation | The Jack Ma Foundation (JMF, established 2014) is the philanthropic foundation of Chinese businessman Jack Ma.
History
In September 2018, Ma announced that he would retire from the company he founded and the source of his wealth, internet merchandiser Alibaba, in order to pursue educational work, philanthropy, and environmental causes.
In 2019 the JMF started the Netpreneur Initiative that grants ten prizes of one million dollars each to ten African entrepreneurs per year and launched a fund with $14.6 million to develop education in Tibet.
In 2020, JMF was announced as one of the alliance partners of Prince William's Earthshot Prize to find solutions to environmental issues.
Coronavirus
In March 2020, in response to the coronavirus pandemic, the Jack Ma Foundation announced its intention to donate a total 500,000 testing kits and 1 million masks to the United States, stating "we join hands with Americans in these difficult times". The Foundation, along with the Alibaba Group, has also donated similar materials to Iran, Italy, Spain, Belgium, Japan and South Korea. He also announced a donation of 1.1 million tests, 6 million masks, and 60,000 protective suits to all African countries to combat the pandemic. For instance in Nigeria a senior health official, Abdulaziz Abdullahi, said that the country had received 100,000 face masks, 1,000 protective gowns and 20,000 test kits.
On 18 March 2020, the JMF published Handbook of COVID-19 Prevention and Treatment, a detailed 68-page book edited by Tingbo Liang that documents the clinical experience obtained at the First Affiliated Hospital of the Zhejiang University School of Medicine in the fight against the coronavirus pandemic.
The BBC called Ma's efforts to send medical equipment to over 150 countries "unrivaled". While Jack Dorsey of Twitter has pledged more money, Ma's shipments of vital supplies might sometimes be more welcome than cash. Beneficiaries include the U.S., Russia, Israel, and Iran; as of April 2020, Ma has declined to donate to any countries such as Honduras and Haiti that have diplomatic ties with Taiwan. Chinese ambassadors are often present at ceremonial handovers of Ma's supplies to beneficiary countries. Ma's shipments appear to have gone smoothly, with the exceptions of Cuba and Eritrea; in contrast, shipments to several countries from the Chinese government have been criticized for being faulty or being too low-quality to use. Following U.S. State Department gratitude over Taiwan's shipment of 2 million masks, the Chinese Foreign Ministry tweeted in April 2020, "Wonder if @StateDept has any comment on Jack Ma's donation of 1 million masks and 500k testing kits as well as Chinese companies' and provinces' assistance?" Chinese media at one point in April 2020 mentioned Ma almost as often as it mentioned Chinese Communist Party leader, Xi Jinping. While Ma is a member of the Chinese Communist Party, some analysts nevertheless believe that the Chinese government may view Ma's personal foreign and domestic popularity as a mixed blessing.
External links
Homepage
References
Jack Ma
Biomedical research foundations
Organizations established in 2018
2018 establishments in China
Organizations associated with the COVID-19 pandemic | Jack Ma Foundation | Engineering,Biology | 665 |
23,693,242 | https://en.wikipedia.org/wiki/C21H36 | {{DISPLAYTITLE:C21H36}}
The molecular formula C21H36 (molar mass: 288.52 g/mol, exact mass: 288.2817 u) may refer to:
Allopregnane, or 5α-Pregnane
Pregnane, also known as 17β-ethylandrostane
5β-Pregnane
Molecular formulas | C21H36 | Physics,Chemistry | 84 |
1,936,678 | https://en.wikipedia.org/wiki/Formula%20Student | Formula Student is a student engineering competition held annually. Student teams from around the world design, build, test, and race a small-scale formula style racing car. The cars are judged on a number of criteria. It is run by the Institution of Mechanical Engineers and uses the same rules as the original Formula SAE with supplementary regulations.
Class definitions
There are three entry classes in Formula Student, designed to allow progressive learning.
Formula Student Class (formerly Class 1)
This is the main event, where teams compete with the cars they have designed and built. Teams are judged across six categories and must pass an inspection by judges before being allowed to compete for the dynamic events. There are usually 100-120 teams in this class.
Concept Class (formerly Class 2)
This is a concept class for teams who only have a project and plan for a Class 1 car. It can include any parts or work that has been completed in the project so far but this is not necessary. Teams are judged on business presentation, cost and design. Schools can enter both FS Class and Concept Class cars, allowing Concept Class to be used for inexperienced students to practise their development in advance of a full Formula Student Class entry.
FS-AI
In 2019 the FS-AI class was introduced for driverless cars.
Class 1A (pre-2012)
This was an alternative fueled class with the emphasis placed upon the environmental impact of racing. A car from the previous year's Class 1 entry could be re-entered and re-engineered allowing the students to concentrate on the low carbon aspect of the competition without having to redesign a new chassis and ancillaries. Cars in Class 1A were judged in the same events alongside Class 1 however the cost category was replaced by one for sustainability and the endurance event had a greater emphasis placed upon measured emissions. Class 1A cars were scored and ranked independently of Class 1. Since 2012, both Petroleum and Alternative fueled cars have competed for places in the same rankings.
Class 2A (pre-2012)
This was a concept class for teams who only had a project and plan for a Class 1A car. It could include any physical parts or work that had been completed for the project so far, but was not essential. Teams were judged on business presentation, cost and design. Schools could enter both Class 1A and Class 2A teams, with Class 2A allowing inexperienced students to gain competition experience in preparation for a full Class 1A entry.
Judging
The cars are judged by industry specialists on the following criteria:
Static events
Engineering design (150 points)
Cost & Manufacturing (115 points)
Business presentation (115 points)
Lap Time Simulation (20 points)
Technical inspection (comprising 6 tests): safety, chassis, noise, tilt, brake, and tech (no points)
Dynamic events
Skidpad (figure of 8) (75 points)
1 km autocross/sprint (100 points)
75 m acceleration (75 points)
22 km endurance (250 points) and fuel economy (100 points)
The winner of the event is the team with the highest number of points out of a maximum of 1000.
History
The first event was held at the Motor Industry Research Association (MIRA) proving ground in 1998. Following that, the event was held for three years at the NEC Birmingham between 1999 and 2001. The event was then held on the Go-Kart track at Bruntingthorpe Aerodrome between 2002 and 2006, before moving to Silverstone Circuit in 2007 where the competition remains until this day. The dynamic events have taken place on Luffield and Brooklands corners in the past but 2012 saw Copse corner and the National Circuit pit straight being used.
Formula Student partnered with Racing Pride in 2019 to support greater inclusivity across the British motorsport industry for LGBT+ fans, employees and drivers.
The FS-AI class enabling driverless cars began in 2019.
Winners
Most wins
Support
Patron: Ross Brawn (former team principal of Mercedes Formula One team),
Ambassadors of Formula Student include David Brabham, Paddy Lowe, Leena Gade, Dallas Campbell, Mike Gascoyne, The Lord Drayson, Baron Drayson (Former Minister of Science) and James Allison.
See also
Formula SAE
Formula SAE Australasia
IIT Bombay Racing
University of Patras Formula Student Team - UoP Racing Team
ETSEIB Motorsport
References
External links
Formula Student
Automotive engineering
Engineering education in the United Kingdom
Formula SAE
Institution of Mechanical Engineers
Motorsport in the United Kingdom
Student competitions
Motorsport
Formula racing | Formula Student | Engineering | 898 |
21,280,618 | https://en.wikipedia.org/wiki/Imre%20Z.%20Ruzsa | Imre Z. Ruzsa (born 23 July 1953) is a Hungarian mathematician specializing in number theory.
Life
He graduated from the Eötvös Loránd University in 1976. Since then he has been at the Alfréd Rényi Institute of Mathematics of the Hungarian Academy of Sciences. He was awarded the Rollo Davidson Prize in 1988. He was elected corresponding member (1998) and member (2004) of the Hungarian Academy of Sciences. He was invited speaker at the European Congress of Mathematics at Stockholm, 2004, and in the Combinatorics section of the International Congress of Mathematicians in Madrid, 2006. In 2012 he became a fellow of the American Mathematical Society.
Work
With Endre Szemerédi he proved subquadratic upper and lower bounds for the Ruzsa–Szemerédi problem on the number of triples of points in which the union of any three triples contains at least seven points. He proved that an essential component has at least (log x)1+ε elements up to x, for some ε > 0. On the other hand, for every ε > 0 there is an essential component that has at most (log x)1+ε elements up to x, for every x. He gave a new proof to Freiman's theorem. Ruzsa also showed the existence of a Sidon sequence which has at least x0.41 elements up to x.
In a result complementing the Erdős–Fuchs theorem he showed that there exists a sequence a0, a1, ... of natural numbers such that for every n the number of solutions of the inequality ai + aj ≤ n is cn + O(n1/4log n) for some c > 0.
Selected publications
See also
Ruzsa triangle inequality
Plünnecke–Ruzsa inequality
References
External links
Some of Ruzsa's papers at the Rényi Institute
1953 births
Living people
Number theorists
20th-century Hungarian mathematicians
21st-century Hungarian mathematicians
Members of the Hungarian Academy of Sciences
Fellows of the American Mathematical Society
International Mathematical Olympiad participants | Imre Z. Ruzsa | Mathematics | 418 |
66,258,404 | https://en.wikipedia.org/wiki/List%20of%20plant%20genera%20named%20for%20people%20%28A%E2%80%93C%29 | Since the first printing of Carl Linnaeus's Species Plantarum in 1753, plants have been assigned one epithet or name for their species and one name for their genus, a grouping of related species. Thousands of plants have been named for people, including botanists and their colleagues, plant collectors, horticulturists, explorers, rulers, politicians, clerics, doctors, philosophers and scientists. Even before Linnaeus, botanists such as Joseph Pitton de Tournefort, Charles Plumier and Pier Antonio Micheli were naming plants for people, sometimes in gratitude for the financial support of their patrons.
Early works researching the naming of plant genera include an 1810 glossary by and an etymological dictionary in two editions (1853 and 1856) by Georg Christian Wittstein. Modern works include The Gardener's Botanical by Ross Bayton, Index of Eponymic Plant Names and Encyclopedia of Eponymic Plant Names by Lotte Burkhardt, Plants of the World by Maarten J. M. Christenhusz (lead author), Michael F. Fay and Mark W. Chase, The A to Z of Plant Names by Allan J. Coombes, the four-volume CRC World Dictionary of Plant Names by Umberto Quattrocchi, and Stearn's Dictionary of Plant Names for Gardeners by William T. Stearn; these supply the seed-bearing genera listed in the first column below. Excluded from this list are genus names not accepted (as of January 2021) at Plants of the World Online, which includes updates to Plants of the World (2017).
Key
Ba = listed in Bayton's The Gardener's Botanical
Bt = listed in Burkhardt's Encyclopedia of Eponymic Plant Names
Bu = listed in Burkhardt's Index of Eponymic Plant Names
Ch = listed in Christenhusz's Plants of the World
Co = listed in Coombes's The A to Z of Plant Names
Qu = listed in Quattrocchi's CRC World Dictionary of Plant Names
St = listed in Stearn's Dictionary of Plant Names for Gardeners
In addition, Burkhardt's Index is used as a reference for every row in the table not cited to Stearn.
Genera
See also
List of plant genus names with etymologies: A–C, D–K, L–P, Q–Z
List of plant family names with etymologies
Notes
Citations
References
See http://creativecommons.org/licenses/by/4.0/ for license.
See http://creativecommons.org/licenses/by/4.0/ for license.
See terms of use.
Further reading
Systematic
Systematic
Taxonomy (biology)
Glossaries of biology
Gardening lists
Genera named for people (A-C)
Named for people (A-C)
Wikipedia glossaries using tables
Lists of eponyms | List of plant genera named for people (A–C) | Biology | 594 |
7,499,898 | https://en.wikipedia.org/wiki/Foundation%20for%20Biomedical%20Research | The Foundation for Biomedical Research (FBR) is an American nonprofit organization, 501(c)(3), located in Washington, DC. Established in 1981, the organization is dedicated to informing the news media, teachers, and other groups about the need for lab animals in medical and scientific research. The organization, together with its partner, the National Association for Biomedical Research (NABR), argues that promoting animal research leads to improved health for both humans and animals.
Its founding president is Frankie Trull.
Animal research
According to the U.S. Department of Agriculture (USDA), the total number of animals used in that country in 2005 was almost 1.2 million, excluding rats and mice. Some animal rights supporters believe that alternatives exist for animal models in research; however the vast majority of scientists believe there are no adequate alternatives which truly replace the roles which research animals play. In fact, recent research shows that 98% of the current drug pipeline relies on either dogs or non-human primates.
According to the Foundation for Biomedical Research, animal research has been responsible for every medical breakthrough over the past century, although this position has been disputed by some animal rights activists and organizations. It cites animal research as leading to advances in antibiotics, blood transfusions, dialysis, organ transplantation, vaccinations, chemotherapy, bypass surgery, joint replacement, and methods for prevention, treatment, cure and control of disease, pain and suffering.
Nonhuman primates
Nonhuman primates have been at the forefront of animal research controversy over the last several years even though they represent less than one percent of all animals models used. In August 2016, to counter criticism from animal rights' groups, a white paper coauthored by nine of the most premier scientific groups and titled The Critical Role of Nonhuman Primates in Medical Research was released. Because of their incredible similarity to humans, primates such as rhesus macaques and chimpanzees, up until the National Institutes of Health ended public funding for chimpanzee research, have greatly contributed to many areas of medicine. Some specific advances, according to the white paper, are: the development of the MMR vaccine, the treatment of leprosy, HIV medication, a vaccine for hepatitis B, and improvements in cancer treatment. One of the most recent advancements has been the development of a highly effective vaccine against the Zika virus, which should soon be protecting both the people and primates that are most at risk of infection.
Dogs
Dogs have been used in research for decades and have been invaluable for treating many human and canine illnesses. Dogs contract many of the diseases humans do, from heart disease to cancer and they are also exposed to the same environment as humans. Canine research has led to many significant breakthroughs such as hip replacements, development of cancer treatments, and research in stem cells, diabetes, and Alzheimer's disease. Treatments for heartworms, parasites, and vaccinations against parvovirus, rabies, and canine distemper have also come from canine models.
Cats
Cats, like dogs, have also proven to be extremely helpful for developing treatments for both human and feline diseases. Cats have been a mainstay in research studies of neurological, cardiovascular, and respiratory diseases and the immune system. In particular, they have been valuable models for understanding the function of the neuron, the chemical transmission of nerve impulses, and the functional organization of the brain. Neuroscientists studying cats have provided a map of the circuitry of the vertebral cortex revealing the major pathways that send signals from the eye to the brain. Cats have also been invaluable for the treatment of leukemia and both feline and human breast cancer. Feline leukemia used to be one of the most common killers of cats and about 85% died within three years of their diagnosis. However, with their help, scientists have developed a vaccine for feline leukemia and now more beloved pets get to spend more time with their families.
Rodents
In the U.S., the numbers of rats and mice used in animal research is estimated at 20 million a year, or 95% of the total number of lab animals. Other rodents commonly used are guinea pigs, hamsters, and gerbils. Mice are the most commonly used vertebrate species because of their size, low cost, ease of handling, and fast reproduction rate. Mice also have genomes that are very similar to the human genome. This similarity allows researchers to recreate human diseases, such as breast cancer, in mice in order to understand how genes affect the development of disease. The Foundation advocates the highest quality of animal care and treatment, stating that the use of animals in research is a privilege, and that animals deserve our respect and the best possible care.
Activities
The Foundation for Biomedical Research conducts educational programs for the news media, teachers, students and parents, pet owners and other groups.
FBR publishes a subscriber-based daily news service called Total E-clips featuring biomedical research news, medical breakthroughs, political and legislative and activism news.
Since 1981, the FBR has monitored and analyzed the activities of animal rights organizations relating to researchers and institutions.
See also
Animal testing
History of animal testing
References
External links
FBR website
NABR website
The Lifesaving Benefits of Primate Research
NHP White Paper
Animal testing
Animal welfare organizations based in the United States | Foundation for Biomedical Research | Chemistry | 1,099 |
632,762 | https://en.wikipedia.org/wiki/Haboush%27s%20theorem | In mathematics Haboush's theorem, often still referred to as the Mumford conjecture, states that for any semisimple algebraic group G over a field K, and for any linear representation ρ of G on a K-vector space V, given v ≠ 0 in V that is fixed by the action of G, there is a G-invariant polynomial F on V, without constant term, such that
F(v) ≠ 0.
The polynomial can be taken to be homogeneous, in other words an element of a symmetric power of the dual of V, and if the characteristic is p>0 the degree of the polynomial can be taken to be a power of p.
When K has characteristic 0 this was well known; in fact Weyl's theorem on the complete reducibility of the representations of G implies that F can even be taken to be linear. Mumford's conjecture about the extension to prime characteristic p was proved by W. J. , about a decade after the problem had been posed by David Mumford, in the introduction to the first edition of his book Geometric Invariant Theory.
Applications
Haboush's theorem can be used to generalize results of geometric invariant theory from characteristic 0, where they were already known, to characteristic p>0. In particular Nagata's earlier results together with Haboush's theorem show that if a reductive group (over an algebraically closed field) acts on a finitely generated algebra then the fixed subalgebra is also finitely generated.
Haboush's theorem implies that if G is a reductive algebraic group acting regularly on an affine algebraic variety, then disjoint closed invariant sets X and Y can be separated by an invariant function f (this means that f is 0 on X and 1 on Y).
C.S. Seshadri (1977) extended Haboush's theorem to reductive groups over schemes.
It follows from the work of , Haboush, and Popov that the following conditions are equivalent for an affine algebraic group G over a field K:
G is reductive (its unipotent radical is trivial).
For any non-zero invariant vector in a rational representation of G, there is an invariant homogeneous polynomial that does not vanish on it.
For any finitely generated K algebra on which G act rationally, the algebra of fixed elements is finitely generated.
Proof
The theorem is proved in several steps as follows:
We can assume that the group is defined over an algebraically closed field K of characteristic p>0.
Finite groups are easy to deal with as one can just take a product over all elements, so one can reduce to the case of connected reductive groups (as the connected component has finite index). By taking a central extension which is harmless one can also assume the group G is simply connected.
Let A(G) be the coordinate ring of G. This is a representation of G with G acting by left translations. Pick an element of the dual of V that has value 1 on the invariant vector v. The map V to A(G) by sending w∈V to the element a∈A(G) with a(g) = (g(w)). This sends v to 1∈A(G), so we can assume that V⊂A(G) and v=1.
The structure of the representation A(G) is given as follows. Pick a maximal torus T of G, and let it act on A(G) by right translations (so that it commutes with the action of G). Then A(G) splits as a sum over characters λ of T of the subrepresentations A(G)λ of elements transforming according to λ. So we can assume that V is contained in the T-invariant subspace A(G)λ of A(G).
The representation A(G)λ is an increasing union of subrepresentations of the form Eλ+nρ⊗Enρ, where ρ is the Weyl vector for a choice of simple roots of T, n is a positive integer, and Eμ is the space of sections of the line bundle over G/B corresponding to a character μ of T, where B is a Borel subgroup containing T.
If n is sufficiently large then Enρ has dimension (n+1)N where N is the number of positive roots. This is because in characteristic 0 the corresponding module has this dimension by the Weyl character formula, and for n large enough that the line bundle over G/B is very ample, Enρ has the same dimension as in characteristic 0.
If q=pr for a positive integer r, and n=q−1, then Enρ contains the Steinberg representation of G(Fq) of dimension qN. (Here Fq ⊂ K is the finite field of order q.) The Steinberg representation is an irreducible representation of G(Fq) and therefore of G(K), and for r large enough it has the same dimension as Enρ, so there are infinitely many values of n such that Enρ is irreducible.
If Enρ is irreducible it is isomorphic to its dual, so Enρ⊗Enρ is isomorphic to End(Enρ). Therefore, the T-invariant subspace A(G)λ of A(G) is an increasing union of subrepresentations of the form End(E) for representations E (of the form E(q−1)ρ)). However, for representations of the form End(E) an invariant polynomial that separates 0 and 1 is given by the determinant. This completes the sketch of the proof of Haboush's theorem.
References
Mumford, D.; Fogarty, J.; Kirwan, F. Geometric invariant theory. Third edition. Ergebnisse der Mathematik und ihrer Grenzgebiete (2) (Results in Mathematics and Related Areas (2)), 34. Springer-Verlag, Berlin, 1994. xiv+292 pp.
Representation theory of algebraic groups
Invariant theory
Theorems in representation theory
Conjectures that have been proved | Haboush's theorem | Physics,Mathematics | 1,279 |
63,481,932 | https://en.wikipedia.org/wiki/Phenserine | {{Infobox drug
| drug_name = Phenserine
| type =
| IUPAC_name = (3aS,8aR)-1,3a,8-Trimethyl-1H,2H,3H,3aH,8H,8aH-pyrrolo[2,3-b]indol-5-yl N-phenylcarbamate
| image = Phenserine.svg
| width =
| alt =
| caption =
| pronounce =
| tradename =
| Drugs.com =
| MedlinePlus =
| licence_EU =
| licence_US =
| DailyMedID =
| pregnancy_AU =
| pregnancy_AU_comment =
| pregnancy_US =
| pregnancy_US_comment =
| pregnancy_category =
| legal_AU =
| legal_AU_comment =
| legal_BR =
| legal_BR_comment =
| legal_CA =
| legal_CA_comment =
| legal_DE =
| legal_DE_comment =
| legal_NZ =
| legal_NZ_comment =
| legal_UK =
| legal_UK_comment =
| legal_US =
| legal_UN =
| legal_US_comment =
| legal_UN_comment =
| legal_status = Investigational
| dependency_liability =
| addiction_liability =
| routes_of_administration = By mouth
| bioavailability = ~100%
| protein_bound =
| metabolism = liver
| metabolites = (−)-N1-norphenserine, (−)-N8-norphenserine, (−)-N1,N8-bisnorphenserine
| onset =
| elimination_half-life = 12.6 minutes
| duration_of_action = 8.25 hours
| excretion = renal or hepatic clearance
| CAS_number = 101246-66-6
| CAS_supplemental =
| ATCvet =
| ATC_prefix =
| ATC_suffix =
| ATC_supplemental =
| PubChem = 192706
| PubChemSubstance =
| IUPHAR_ligand =
| DrugBank = DB04892
| ChemSpiderID = 167225
| UNII = SUE285UG3S
| KEGG =
| ChEBI =
| ChEMBL = 74926
| NIAID_ChemDB =
| PDB_ligand =
| synonyms = (-)-Phenserine, (-)-Eseroline phenylcarbamate, N-phenylcarbamoyleseroline, N''-phenylcarbamoyl eseroline
| chemical_formula =
| C = 20
| H = 23
| N = 3
| O = 2
| charge =
| SMILES = [H][C@]12N(C)CC[C@@]1(C)C1=C(C=CC(OC(=O)NC3=CC=CC=C3)=C1)N2C
| StdInChI = InChI=1S/C20H23N3O2/c1-20-11-12-22(2)18(20)23(3)17-10-9-15(13-16(17)20)25-19(24)21-14-7-5-4-6-8-14/h4-10,13,18H,11-12H2,1-3H3,(H,21,24)/t18-,20+/m1/s1
| StdInChI_comment =
| StdInChIKey = PBHFNBQPZCRWQP-QUCCMNQESA-N
| density =
| density_notes =
| melting_point = 150
| melting_high =
| melting_notes =
| solubility =
| specific_rotation =
| INN =
| licence_CA =
| class =
| Jmol =
| sol_units =
}}Phenserine (also known as (-)-phenserine or (-)-eseroline phenylcarbamate''') is a synthetic drug which has been investigated as a medication to treat Alzheimer's disease (AD), as the drug exhibits neuroprotective and neurotrophic effects.
The research of phenserine, initially patented by the National Institute on Aging (NIA), has been suspended since phase III of clinical trials in 2006, conducted right after the drug licenses were issued. The abandonment of the clinical trials led to disapproval by FDA. The retrospective meta-analysis of the phenserine research proposed that its clinical invalidation was arisen from methodological issues that were not impeccably settled before proceeding to the subsequent clinical phases.
Phenserine was introduced as an inhibitor of acetylcholinesterase (AChE) and demonstrated significant alleviation in numerous neuropathological manifestations, improving cognitive functions of the brain. The ameliorative mechanism involves both cholinergic and non-cholinergic pathways.
The clinical translatable doses of phenserine show relatively high tolerability and rarely manifest severe adverse effects. With respect to overdosing of the drug (20 mg/kg), a few cholinergic adverse effects were reported, including nausea and tremor which are not life-threatening.
An administration form of phenserine, (-)-phenserine tartrate, which exhibits high bioavailability and solubility, is taken by mouth. Phenserine and its metabolites can readily access the brain with high permeability across the blood-brain barrier and sustain to act for a long duration with the relatively short half-life. Posiphen ((+)-phenserine), the enantiomer of (-)-phenserine, is also a potential drug by itself or synergically with (-)-phenserine, to mitigate the progression of neurological diseases, mainly Alzheimer's disease.
History
Phenserine was first investigated as a substitute for physostigmine which failed to satisfy the clinical standards for treating Alzheimer's disease, and developed into more compatible remedy. It was initially invented by Nigel Greig whose laboratory is affiliated with the National Institute on Aging (NIA) under the US National Institutes of Health (NIH) which subsequently released a patent of phenserine as an AChE inhibitor in 1995. During phase I in 2000, the supplementary patent regarding its inhibitory mechanism upon β-amyloid precursor protein (APP) synthesis was added. Following 6 years of phase I and II trials, Axonyx Corporation had licensed phenserine to Daewoong Pharmaceutical and QR Pharma (later adopted new corporation name, Annovis Bio) companies in 2006, which then planned to undertake phase III trial and merchandize the drug. However, the clinical deficits ̶ representatively from a double-blinded, placebo-controlled and 7-month phase III trial which had been conducted on 377 mild to moderate Alzheimer's disease patients across Austria, Croatia, Spain, and UK ̶ were discovered and no significance was exhibited for the drug efficacy. This led to the relinquishment of phenserine development, merely displaying its marketable potential.
Approval status
Phenserine failed in phase III of Alzheimer's disease-aimed clinical trials and there has yet been no promise of the trial resumption since 2006. The methodological problems of trials are frequently speculated as the principal reason for the failure of FDA approval as well as the scarcity of Alzheimer's disease drugs. The underlying complications are generated by an inordinate variance in clinical outcomes and poor determination in optimal dosing.
Intra and inter-site variations were incurred by a lack of baseline evaluation and longitudinal assessment on placebo groups. This produced an inadequate power and, thus, appeared to have insufficient statistical significance. In light of the dose determination, the criteria for human subject engagement was not meticulously established before dosing and the effective dose range was not completely established in phase I and II, yet still persisting to phase III. Compared to other Alzheimer's disease drugs, such as donepenzil, tacrine and metrifonate, the clinical advancement of phenserine involves comparably high compliance in outcome measures and protocol regimentation on methods and the clinical phase transition.
Pharmacological benefits
Phenserine was invented as the Alzheimer's disease-oriented treatment in particular, and also proven to have alleviative effects upon other neurological disorders, Parkinson's disease, dementia and amyotrophic lateral sclerosis. The administration of phenserine within the short delay of the disease onset was shown to diminish the severity of neurodegeneration and accompanying cognitive impairments. Its post-injury intervention at clinical translatable doses has been shown to significantly mitigate various neurodegenerative manifestations, preventing chronic deterioration in cognitive functions. The collective neuropathological cascades in the brain are either naturally occurring or provoked by mild or moderate traumatic brain injuries, such as concussion, diffuse axonal injury, ischemic and hypoxic brain injuries The traumatic brain injuries have been substantially examined and induced to form test groups in phenserine research. They are highly correlated with the onset of neurodegenerative disorders, precipitating cognitive, and behavioral impairments.
Phenserine was proven to mitigate the multiple cascades of neuropathology, triggered by traumatic brain injuries, via both cholinergic and non-cholinergic mechanisms.
Pharmacodynamics (mechanism of action)
Cholinergic mechanism
Phenserine serves as an acetylcholinesterase (AChE) inhibitor which selectively acts on the acetylcholinesterase enzyme. It prevents acetylcholine from being hydrolyzed by the enzyme and enables the neurotransmitter to be further retained at the synaptic clefts. Such mechanism promotes the cholinergic neuronal circuits to be activated and thereby enhances memory and cognition in Alzheimer's subjects.
Non-cholinergic mechanism
In clinical trials, phenserine was demonstrated to alleviate neurodegeneration, repressing the programmed neuronal cell death and enhancing the stem cell survival and differentiation. The alleviation can be achieved by increase in levels of neurotrophic BDNF and anti-apoptotic protein, Bcl-2, which subsequently reduces expressions of pro-apoptotic factors, GFAP and activates caspase 3. The treatment also suppresses the levels of Alzheimer's disease-inducing proteins which are β-amyloid precursor protein (APP) and Aβ peptide. The drug interaction with the APP gene mediates the expression of both APP and its following product, Aβ protein. This regulating action reverses the glial cell-favored differentiation and increases the neuronal cell output.
Phenserine also attenuates the neuroinflammation which involves the excessive activation of microglial cells to remove the cellular wastes from injury lesions. The accumulation of the activated glia near the site of brain injury is unnecessarily prolonged, stimulating the oxidative stress. The inflammatory response was significantly weakened with the introduction of phenserine, which was evidenced with discouraged expression of pro-inflammatory markers, IBA 1 and TNF-α. The disrupted integrity of the blood brain barrier by a degrading chemical, MMP-9, leading to neuroinflammation, is restored by phenserine as well.
The alpha-synucleins, the toxic aggregates resulting from the protein misfolding, are highly observed in Parkinson's disease. The drug therapy was proven to neutralize the toxicity of alpha-synucleins via protein translation, alleviating the symptoms of the disease.
Dosage
Clinically, the translatable dose of phenserine was primarily employed within a range of 1 to 5 mg/kg where the unit calibration took account of the body surface area. This standard dose range was generally well tolerated in long term trials by neuronal cell cultures, animal models and humans. Increment in dosing by 10 mg/kg is still tolerated without instigating any physiological implication. The maximal administration of phenserine up to 15 mg/kg was reported in rats.
Overdose
The dose of 20 mg/kg and above are appraised as overdosing in which cholinergic adverse effects ensue.
The symptoms of overdosing includes:
Nausea
Vomiting
Dizziness
Tremors
Bradycardia
Mild symptoms were notified in clinical trials but no other seriously considerable adverse effects were expressed. Tremor was also noted as one of the dose-limiting actions.
Chemistry
Pharmacokinetics
Oral bioavailability of phenserine was shown to be very high, up to 100%. Its bioavailability was tested by computing the drug's delivery rate across the rat's blood brain barrier. The drug concentration, reached in the brain, is 10-fold higher than plasma levels, verifying phenserine as a brain-permeable AChE inhibitor.
Relative to its short plasma half life of 8 to 12 minutes, phenserine exhibits a long duration of action with the half-life of 8.25 hours in which the hindering effect on AChE is time-dependently faded. With the administration of phenserine, 70% or higher AChE inhibitory action in the blood was observed in preclinical studies and with systemic phenserine administration, the extracellular ACh level in the striatum increased up to three times. Through PET studies and microdialysis, the compound's brain permeability was able to be further elucidated.
Enantiomer (posiphen)
(-)-Phenserine, generally referred to phenserine, acts as an active enantiomer for the inhibition of acetylcholinesterase (AChE) while posiphen, its alternative enantiomer, was comparably demonstrated as a poor AChE inhibitor.
In the history of posiphen research, several companies were interactively involved. In 2005, an Investigational New Drug (IND) application of posiphen was filed with FDA by TorreyPines Therapeutics while its phase I trial on animal models had been implemented by Axonyx. Axonyx and TorreyPines Therapeutics officially signed for their merger agreement in 2006 and licensed the drug to QR Pharma in 2008. The clinical trials of posiphen against Alzheimer's disease are still underway.
Interactions
Currently, 282 drugs have been reported to make interactions with phenserine.
Current research
A 5-year double blinded, donepezil-controlled clinical study for validation of Alzheimer's disease course modification using phenserine has been undertaken as from 2018, involving 200 patients in the UK and US. The study aims to reduce variation in AD therapeutic response between patients via optimal dose formulation.
References
Experimental drugs for Alzheimer's disease
Neuroprotective agents
Neurotrophic factors | Phenserine | Chemistry | 3,150 |
2,823,760 | https://en.wikipedia.org/wiki/Tonicity | In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-impermeable solutes across a cell membrane which determine the direction and extent of osmotic flux. It is commonly used when describing the swelling-versus-shrinking response of cells immersed in an external solution.
Unlike osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an effective osmotic pressure. Solutes able to freely cross the membrane do not affect tonicity because they will always equilibrate with equal concentrations on both sides of the membrane without net solvent movement. It is also a factor affecting imbibition.
There are three classifications of tonicity that one solution can have relative to another: hypertonic, hypotonic, and isotonic. A hypotonic solution example is distilled water.
Hypertonic solution
A hypertonic solution has a greater concentration of non-permeating solutes than another solution. In biology, the tonicity of a solution usually refers to its solute concentration relative to that of another solution on the opposite side of a cell membrane; a solution outside of a cell is called hypertonic if it has a greater concentration of solutes than the cytosol inside the cell. When a cell is immersed in a hypertonic solution, osmotic pressure tends to force water to flow out of the cell in order to balance the concentrations of the solutes on either side of the cell membrane. The cytosol is conversely categorized as hypotonic, opposite of the outer solution.
When plant cells are in a hypertonic solution, the flexible cell membrane pulls away from the rigid cell wall, but remains joined to the cell wall at points called plasmodesmata. The cells often take on the appearance of a pincushion, and the plasmodesmata almost cease to function because they become constricted, a condition known as plasmolysis. In plant cells the terms isotonic, hypotonic and hypertonic cannot strictly be used accurately because the pressure exerted by the cell wall significantly affects the osmotic equilibrium point.
Some organisms have evolved intricate methods of circumventing hypertonicity. For example, saltwater is hypertonic to the fish that live in it. Because the fish need a large surface area in their gills in contact with seawater for gas exchange, they lose water osmotically to the sea from gill cells. They respond to the loss by drinking large amounts of saltwater, and actively excreting the excess salt. This process is called osmoregulation.
Hypotonic solution
A hypotonic solution has a lower concentration of solutes than another solution. In biology, a solution outside of a cell is called hypotonic if it has a lower concentration of solutes relative to the cytosol. Due to osmotic pressure, water diffuses into the cell, and the cell often appears turgid, or bloated.
For cells without a cell wall such as animal cells, if the gradient is large enough, the uptake of excess water can produce enough pressure to induce cytolysis, or rupturing of the cell.
When plant cells are in a hypotonic solution, the central vacuole takes on extra water and pushes the cell membrane against the cell wall. Due to the rigidity of the cell wall, it pushes back, preventing the cell from bursting. This is called turgor pressure.
Isotonicity
A solution is isotonic when its effective osmole concentration is the same as that of another solution. In biology, the solutions on either side of a cell membrane are isotonic if the concentration of solutes outside the cell is equal to the concentration of solutes inside the cell. In this case the cell neither swells nor shrinks because there is no concentration gradient to induce the diffusion of large amounts of water across the cell membrane. Water molecules freely diffuse through the plasma membrane in both directions, and as the rate of water diffusion is the same in each direction, the cell will neither gain nor lose water.
An iso-osmolar solution can be hypotonic if the solute is able to penetrate the cell membrane. For example, an iso-osmolar urea solution is hypotonic to red blood cells, causing their lysis. This is due to urea entering the cell down its concentration gradient, followed by water. The osmolarity of normal saline, 9 grams NaCl dissolved in water to a total volume of one liter, is a close approximation to the osmolarity of NaCl in blood (about 290 mOsm/L). Thus, normal saline is almost isotonic to blood plasma. Neither sodium nor chloride ions can freely pass through the plasma membrane, unlike urea.
See also
Osmotic concentration
Osmosis
Salinity
References
Cell biology | Tonicity | Biology | 1,045 |
1,195,257 | https://en.wikipedia.org/wiki/Reverberation%20room | A reverberation room or reverberation chamber is a room designed to create reverberation, a diffuse or random incidence sound field (i.e. one with a uniform distribution of acoustic energy and random direction of sound incidence over a short time period). Reverberation chambers tend to be large rooms (the resulting sound field becomes more diffused with increased path length) and have very hard exposed surfaces. The change of impedance (compared to the air) these surfaces present to incident sound is so large that virtually all of the acoustic energy that hits a surface is reflected back into the room. Arranging the room surfaces (including the ceiling) to be non-parallel helps inhibit the formation of standing waves - additional acoustic diffusers are often used to create more reflecting surfaces and further encourage even distribution of any particular sound field.
Reverberation chambers are used in acoustics as well as in electrodynamics, such as for measurement microphone calibration, measurement of the sound power of a source, and measurement of the absorption coefficient of a material. All these techniques assume the sound field in the chamber to be diffuse, and will normally use a broadband sound source (e.g. white noise or pink noise) so that the resulting sound field contains acoustic energy across the whole audible range.
See also
Anechoic chamber, an acoustic test facility which minimizes reverberation
Echo chamber, a reverberation room used for music recording
Electromagnetic reverberation chamber, an electromagnetic environment mainly for electromagnetic compatibility testing
References
ISO Standard for Measurement of Acoustic Absorption in a Reverberation Room
External links
360 video of a reverberation chamber
Pictures and further description of a reverberation chamber
Acoustics | Reverberation room | Physics | 352 |
446,606 | https://en.wikipedia.org/wiki/Modularity%20of%20mind | Modularity of mind is the notion that a mind may, at least in part, be composed of innate neural structures or mental modules which have distinct, established, and evolutionarily developed functions. However, different definitions of "module" have been proposed by different authors. According to Jerry Fodor, the author of Modularity of Mind, a system can be considered 'modular' if its functions are made of multiple dimensions or units to some degree. One example of modularity in the mind is binding. When one perceives an object, they take in not only the features of an object, but the integrated features that can operate in sync or independently that create a whole. Instead of just seeing red, round, plastic, and moving, the subject may experience a rolling red ball. Binding may suggest that the mind is modular because it takes multiple cognitive processes to perceive one thing.
Early investigations
Historically, questions regarding the functional architecture of the mind have been divided into two different theories of the nature of the faculties. The first can be characterized as a horizontal view because it refers to mental processes as if they are interactions between faculties such as memory, imagination, judgement, and perception, which are not domain specific (e.g., a judgement remains a judgement whether it refers to a perceptual experience or to the conceptualization/comprehension process). The second can be characterized as a vertical view because it claims that the mental faculties are differentiated on the basis of domain specificity, are genetically determined, are associated with distinct neurological structures, and are computationally autonomous.
The vertical vision goes back to the 19th-century movement called phrenology and its founder Franz Joseph Gall. Gall claimed that the individual mental faculties could be associated precisely, in a one-to-one correspondence, with specific physical areas of the brain. For example, someone's level of intelligence could be literally "read off" from the size of a particular bump on his posterior parietal lobe. Phrenology's practice was debunked scientifically by Pierre Flourens in the 19th century. He destroyed parts of pigeons' and dogs' brains, called lesions, and studied the organisms' resulting dysfunction. He was able to conclude that while the brain localizes in some functions, it also works as a unit and is not as localized as earlier phrenologists thought. Before the early 20th century, Edward Bradford Titchener studied the modules of the mind through introspection. He tried to determine the original, raw perspective experiences of his subjects. For example, if he wanted his subjects to perceive an apple, they would need to talk about spatial characteristics of the apple and the different hues that they saw without mentioning the apple.
Fodor's Modularity of Mind
In the 1980s, however, Jerry Fodor revived the idea of the modularity of mind, although without the notion of precise physical localizability. Drawing from Noam Chomsky's idea of the language acquisition device and other work in linguistics as well as from the philosophy of mind and the implications of optical illusions, he became a major proponent of the idea with the 1983 publication of Modularity of Mind.
According to Fodor, a module falls somewhere between the behaviorist and cognitivist views of lower-level processes.
Behaviorists tried to replace the mind with reflexes, which are, according to Fodor, encapsulated (cognitively impenetrable or unaffected by other cognitive domains) and non-inferential (straight pathways with no information added). Low-level processes are unlike reflexes in that they can be inferential. This can be demonstrated by poverty of the stimulus argument, which posits that children do not only learn language from their environment, but are innately programmed with low-level processes that help them seek and learn language. The proximate stimulus, that which is initially received by the brain (such as the 2D image received by the retina), cannot account for the resulting output (for example, our 3D perception of the world), thus necessitating some form of computation.
In contrast, cognitivists saw lower-level processes as continuous with higher-level processes, being inferential and cognitively penetrable (influenced by other cognitive domains, such as beliefs). The latter has been shown to be untrue in some cases, such as the Müller-Lyer illusion, which can persist despite a person's awareness of their existence. This is taken to indicate that other domains, including one's beliefs, cannot influence such processes.
Fodor arrives at the conclusion that such processes are inferential like higher-order processes and encapsulated in the same sense as reflexes.
Although he argued for the modularity of "lower level" cognitive processes in Modularity of Mind he also argued that higher-level cognitive processes are not modular since they have dissimilar properties. The Mind Doesn't Work That Way, a reaction to Steven Pinker's How the Mind Works, is devoted to this subject.
Fodor (1983) states that modular systems must—at least to "some interesting extent"—fulfill certain properties:
Domain specificity: modules only operate on certain kinds of inputs—they are specialised
Obligatory firing: modules process in a mandatory manner
Limited accessibility: what central processing can access from input system representations is limited
Fast speed: probably due to the fact that they are encapsulated (thereby needing only to consult a restricted database) and mandatory (time need not be wasted in determining whether or not to process incoming input)
Informational encapsulation: modules need not refer to other psychological systems in order to operate
Shallow outputs: the output of modules is very simple
Specific breakdown patterns
Characteristic ontogeny: there is a regularity of development
Fixed neural architecture.
Pylyshyn (1999) has argued that while these properties tend to occur with modules, one—information encapsulation—stands out as being the real signature of a module; that is the encapsulation of the processes inside the module from both cognitive influence and from cognitive access. One example is that conscious awareness that the Müller-Lyer illusion is an illusion does not correct visual processing.
Evolutionary psychology and massive modularity
The definition of module has caused confusion and dispute. In J.A. Fodor's views, modules can be found in peripheral and low-level visual processing, but not in central processing. Later, he narrowed the two essential features to domain-specificity and information encapsulation. According to Frankenhuis and Ploeger, domain-specificity means that "a given cognitive mechanism accepts, or is specialized to operate on, only a specific class of information". Information encapsulation means that information processing in the module cannot be affected by information in the rest of the brain. One example is that the effects of an optical illusion, created by low-level processes, persist despite high-level processing caused by conscious awareness of the illusion itself.
Other perspectives on modularity come from evolutionary psychology. Evolutionary psychologists propose that the mind is made up of genetically influenced and domain-specific mental algorithms or computational modules, designed to solve specific evolutionary problems of the past. Modules are also used for central processing. This theory is sometimes referred to as massive modularity. Leda Cosmides and John Tooby claimed that modules are units of mental processing that evolved in response to selection pressures. To them, each module was a complex computer that innately processed distinct parts of the world, like facial recognition, recognizing human emotions, and problem-solving. On this view, much modern human psychological activity is rooted in adaptations that occurred earlier in human evolution, when natural selection was forming the modern human species.
A 2010 review by evolutionary psychologists Confer et al. suggested that domain general theories, such as for "rationality", has several problems: 1. Evolutionary theories using the idea of numerous domain-specific adaptions have produced testable predictions that have been empirically confirmed; the theory of domain-general rational thought has produced no such predictions or confirmations. 2. The rapidity of responses such as jealousy due to infidelity indicates a domain-specific dedicated module rather than a general, deliberate, rational calculation of consequences. 3. Reactions may occur instinctively (consistent with innate knowledge) even if a person has not learned such knowledge. One example being that in the ancestral environment it is unlikely that males during development learn that infidelity (usually secret) may cause paternal uncertainty (from observing the phenotypes of children born many months later and making a statistical conclusion from the phenotype dissimilarity to the cuckolded fathers). With respect to general purpose problem solvers, Barkow, Cosmides, and Tooby (1992) have suggested in The Adapted Mind: Evolutionary Psychology and The Generation of Culture that a purely general problem solving mechanism is impossible to build due to the frame problem. Clune et al. (2013) have argued that computer simulations of the evolution of neural nets suggest that modularity evolves because, compared to non-modular networks, connection costs are lower.
Several groups of critics, including psychologists working within evolutionary frameworks, argue that the massively modular theory of mind does little to explain adaptive psychological traits. Proponents of other models of the mind argue that the computational theory of mind is no better at explaining human behavior than a theory with mind entirely a product of the environment. Even within evolutionary psychology there is discussion about the degree of modularity, either as a few generalist modules or as many highly specific modules. Other critics suggest that there is little empirical support in favor of the domain-specific theory beyond performance on the Wason selection task, a task critics state is too limited in scope to test all relevant aspects of reasoning. Moreover, critics argue that Cosmides and Tooby's conclusions contain several inferential errors and that the authors use untested evolutionary assumptions to eliminate rival reasoning theories.
Criticisms of the notion of modular minds from genetics include that it would take too much genetic information to form innate modularity of mind, the limits to the possible amount of functional genetic information being imposed by the number of mutations per generation that led to the prediction that only a small part of the human genome can be functional in an information-carrying way if an impossibly high rate of lethal mutations is to be avoided, and that selection against lethal mutations would have stopped and reversed any increase in the amount of functional DNA long before it reached the amount that would be required for modularity of mind. It is argued that proponents of the theory of mind conflate this with the straw man argument of assuming no function in any non-protein-coding DNA when pointing at discoveries of some parts of non-coding DNA having regulatory functions, while the actual argument of limited amount of functional DNA does acknowledge that some parts of non-coding DNA can have functions but putting bounds on the total amount of information-bearing genetic material regardless of whether or not it codes for proteins, in agreement with the discoveries of regulatory functions of non-coding DNA extending only to parts of it and not be generalized to all DNA that does not code for proteins. The maximum amount of information-carrying heredity is argued to be too small to form modular brains.
Wallace (2010) observes that the evolutionary psychologists' definition of "mind" has been heavily influenced by cognitivism and/or information processing definitions of the mind. Critics point out that these assumptions underlying evolutionary psychologists' hypotheses are controversial and have been contested by some psychologists, philosophers, and neuroscientists. For example, Jaak Panksepp, an affective neuroscientist, point to the "remarkable degree of neocortical plasticity within the human brain, especially during development" and states that "the developmental interactions among ancient special-purpose circuits and more recent general-purpose brain mechanisms can generate many of the "modularized" human abilities that evolutionary psychology has entertained."
Philosopher David Buller agrees with the general argument that the human mind has evolved over time but disagrees with the specific claims evolutionary psychologists make. He has argued that the contention that the mind consists of thousands of modules, including sexually dimorphic jealousy and parental investment modules, are unsupported by the available empirical evidence. He has suggested that the "modules" result from the brain's developmental plasticity and that they are adaptive responses to local conditions, not past evolutionary environments. However, Buller has also stated that even if massive modularity is false this does not necessarily have broad implications for evolutionary psychology. Evolution may create innate motives even without innate knowledge.
In contrast to modular mental structure, some theories posit domain-general processing, in which mental activity is distributed across the brain and cannot be decomposed, even abstractly, into independent units. A staunch defender of this view is William Uttal, who argues in The New Phrenology (2003) that there are serious philosophical, theoretical, and methodological problems with the entire enterprise of trying to localise cognitive processes in the brain. Part of this argument is that a successful taxonomy of mental processes has yet to be developed.
Merlin Donald argues that over evolutionary time the mind has gained adaptive advantage from being a general problem solver. The mind, as described by Donald, includes module-like "central" mechanisms, in addition to more recently evolved "domain-general" mechanisms.
See also
Automatic and Controlled Processes (ACP)
Faculty psychology
Jerry Fodor on mental architecture
Language module
Modularity
Neuroconstructivism
Neuroplasticity
Peter Carruthers (philosopher)
Society of Mind which proposes the mind is made up of agents
Visual modularity
References
Further reading
Pylyshyn, Z.W. (1984). Computation and cognition: Toward a foundation for cognitive science. Cambridge, Massachusetts: MIT Press (Also available through CogNet).
Animal Minds: Beyond Cognition to Consciousness Donald R. Griffin, University of Chicago Press, 2001 ()
Shallice, Tim, & Cooper, Rick. (2011). The Organisation of Mind. Oxford: Oxford University Press. Chapter 3: Bridging the Theoretical Gap: from the Brain to Cognitive Theory (pp. 67–107).
Online videos
RSA talk by evolutionary psychologist Robert Kurzban on modularity of mind, based on his book, Why Everyone (Else) is a Hypocrite
Stone Age Minds: A conversation with evolutionary psychologists Leda Cosmides and John Tooby
Video of a computer simulation of the evolution of modularity in neural nets.
Behavioural sciences
Cognition
Cognitive architecture
Cognitive science
Evolutionary psychology
Ethology
Semantics
Metaphysics of mind | Modularity of mind | Engineering,Biology | 2,993 |
30,777,816 | https://en.wikipedia.org/wiki/Richard%20W.%20Ziolkowski | Richard W. Ziolkowski is an American electrical engineer and academician, who was the president of the IEEE Antennas and Propagation Society (2005), and a former vice president of this same society (2004). In 2006, he became an OSA Fellow. He is also an IEEE Fellow. He was born on November 22, 1952, in Warsaw, New York.
Career
Ziolkowski has a dual appointment at the University of Arizona. He is a professor of electrical and computer engineering, and a professor of the optical sciences. He has been a full professor of electrical and computer engineering since 1996. Has been a professor of optical sciences since 2006. In 1990, he began at the University of Arizona as an associate professor in the department of Electrical and Computer Engineering. During his time at this university he was awarded the Kenneth Von Behren Chaired Professor (2003–2005) and is currently the Litton Industries John M. Leonis Distinguished Professor.
Before his first position at the University of Arizona, he was employed by Lawrence Livermore National Laboratory from 1981 to 1990.
2010-present
In 2012, he was awarded a Honorary Doctorate from the Technical University of Denmark (DTU), in recognition of “outstanding and seminal contributions to metamaterial-inspired antennas.” The ceremony was attended by Queen Margrethe II of Denmark and the US Ambassador to Denmark, Laurie S. Fulton.
From 2014 to 2015, Ziolkowski was the Fulbright Distinguished Chair in Advanced Science and Technology for the Australian Defense Science and Technology Organization, where he conducted research on metamaterial-engineered structures and how these structures can be used to control scattering and absorption of electromagnetic and acoustic waves.
As of 2016, Ziolkowski is serving as a distinguished professor at the University of Technology Sydney (UTS), in Sydney, Australia, where he is continuing his metamaterials research.
Education and training
At Brown University, in 1974, Richard Ziolkowski earned an Sc.B degree in physics, magna cum laude with honors. He then attended the University of Illinois at Urbana-Champaign. There he received both his M.S. and Ph.D. degrees in physics, in 1975 and 1980, respectively. While earning his graduate degrees, Ziolkowski was also a Graduate Teaching Assistant (1974–1977) and then Graduate Research Assistant (1975–1976). During his doctoral studies, he was supervised by Georges A. Deschamps.
Society memberships
His academic and research achievement, can be reflected by his membership in the engineering honor society Tau Beta Pi, the honor society of research scientists and engineers Sigma Xi, and the multidisciplinary, academic, honor society Phi Kappa Phi.
Richard Ziolkowski is also a current member of the IEEE Antennas and Propagation Society, the IEEE Microwave Theory and Techniques Society, and the American Physical Society.
Concurrently he is also a member of United States segment of International Union of Radio Science (URSI). Regarding URSI, Ziolkowski's membership is more specifically - commission B of URSI, which focuses on fields, waves, electromagnetic theory, and their applications - and commission D of URSI, which focuses on electronics and photonics.
He is also a current member of the Optical Society of America, and the Acoustical Society of America.
Invited speaker
Professor Ziolkowski has received technical recognition for his work as an invited speaker and invited lecturer in various venues.
2009
In 2009, Professor Ziolkowski was an invited lecturer at CEA Cesta (France), a European workshop on metamaterials (Rome), Metamaterials 2009 (London), Institute for Infocomm Research (Singapore), a metamaterials workshop (Madrid), ETOPIM 8 (Crete), metamaterials workshop (Los Alamos), IWAT 2009 (in Santa Monica, Ca.), and ANTEM / URSI 2009 (Canada).
2008
In 2008, he was an invited speaker (or lecturer) at A*STAR Metamaterials Workshop (Singapore), ISAP 2008 (Taipei), XII School on Metamaterials (Spain), XI School on Metamaterials (Marrakesh, Morocco), Europe SPIE Conference 6987 (Strasbourg, France), and Northeastern University (January 24).
2007
In 2007, he was an invited speaker (or lecturer) at the University of Toronto, ISAP 2007 (Niigata, Japan), IWAT 2007 (Cambridge, UK), and NANOMETA 2007(Austria).
Service positions
Ziolkowski has served in the following positions:
Chairperson, IEEE Electromagnetics Award Committee (2008–2010)
IEEE Antennas and Propagation Society, President, 2005
IEEE Antennas and Propagation Society, Vice President, 2004
University of Arizona Faculty Honor Marshall, Commencement May 2005
University of Arizona Faculty Honor Marshall, Commencement December 2004
Chairman for Subcommittee IV: Nanostructure Photonics of Optical Society of America from 2000 to 2001
Secretary for the United States segment of the URSI Commission D from 2000 to 2002
Secretary for the United States segment of the URSI Commission B from 1994 to 1996
Vice Chairman for the joint international symposium of URSI and IEEE Antennas and Propagation Society 1989
Chairman of the Technical Activities Committee of the United States segment URSI Commission B from 1996 to 1999
Awards and honors
Ziolkowski has received the following awards:
Professional society awards:
APS Fellow, 2016
OSA Fellow, 2006
IEEE Fellow, 1994
Teaching awards
IEEE and ΗΚΝ Outstanding Teaching Award (Senior Faculty) 1998
IEEE and ΗΚΝ Outstanding Teaching Award 1993
Tau Beta Pi Professor of the Year Award 1993
University of Arizona service awards
Litton Industries John M. Leonis Distinguished Professor from March 2007 to the present
University of Arizona Kenneth Von Behren Chaired Professor, November 2003 – July 2005
University of Arizona New Traditional Outstanding Advisor Recognition 1994
Published works
Ziolkowski received recognition for best paper in several venues. In August 2007 he received the Best Paper Award at the International Symposium on Antennas and Propagation (Niigata, Japan). In April 2006 he received the CST University Publication Award. Also in 2006 he received recognition from the Institute of Electronics, Information and Communication Engineers for the Best Review Paper Award.
Professor Ziolkowski is a co-author and co-editor of Metamaterials: Physics and Engineering Explorations with Nader Engheta.
He is also a contributor to other books.
Current areas of research
Among other research areas, his research covers metamaterial-engineered antennas This includes configurations and combinations of single-negative metamaterials, double-negative metamaterials, and naturally occurring materials. The study of these materials pertains to how these may affect scatterers, radiators, fields, resonators, gain, and further miniaturization. He has authored and co-authored over 30 papers (2005–2010) related to this area.
His inquiries also cover fundamental research in metamaterials by studying how the properties of these materials, and their use, may affect various electromagnetic devices.
Highly cited articles
Citations rates for some peer reviewed articles authored by Professor Ziolkowski have surpassed 1000 citations. For example, his 2001 article published in Physical Review E is cited more than 1264 times. His book "Metamaterials: Physics and Engineering Explorations" has been cited more than 2533 times. In another instance, a 2003 paper that Professor Ziolkowski published in IEEE Transactions on Antennas and Propagation has over 1029 citations. Finally, IEEE Transactions on Microwave Theory and Techniques published a 2005 paper, by this author, which currently has a citation rate of more than 200.
See also
Metamaterial scientists
Andrea Alù
Nader Engheta
George V. Eleftheriades
Ulf Leonhardt
Ismo V. Lindell
John Pendry
Vladimir Shalaev
Ari H. Sihvola
David R. Smith
Costas Soukoulis
Sergei A. Tretyakov
Victor Veselago
Past artificial material scientists
Jagadish Chandra Bose
Horace Lamb
Winston E. Kock
Karl F. Lindman
Leonid Mandelstam
Walter Rotman
Sergei Schelkunoff
Arthur Schuster
References
Living people
1952 births
People from Warsaw, New York
Brown University alumni
Grainger College of Engineering alumni
University of Arizona faculty
Metamaterials scientists
American electrical engineers
Fellows of the IEEE
Fellows of Optica (society)
Engineers from New York (state)
Microwave engineers
Optical engineers
Electrical engineering academics
Fellows of the American Physical Society | Richard W. Ziolkowski | Materials_science | 1,709 |
47,684,113 | https://en.wikipedia.org/wiki/List%20of%20explosions | This is a list of accidental explosions and facts about each one, grouped by the time of their occurrence. It does not include explosions caused by terrorist attacks or arson, as well as intentional explosions for civil or military purposes. It may still include entries for which the cause is unclear or still under investigation. For a list based on power or death toll see largest artificial non-nuclear explosions or the explosions section of list of accidents and disasters by death toll. This list also contains notable explosions that would not qualify for the articles mentioned above and is more detailed, especially for the latest centuries.
Prior to 2000
2000s
2010s
2020s
See also
List of accidents and incidents involving transport or storage of ammunition
List of ammonium nitrate disasters
List of boiler explosions
List of boiling liquid expanding vapor explosions
List of pipeline accidents
List of gas explosions
References
+ | List of explosions | Chemistry | 165 |
955,781 | https://en.wikipedia.org/wiki/UTStarcom | UTStarcom Holdings Corp. () is a Chinese global telecom infrastructure provider headquartered in Beijing. The company develops and supplies a broad range of telecommunication devices to communications service providers and network operators including fixed and mobile network operators, as well as to enterprises. Traditionally, the company had focused on markets in China, Japan, and India, but has expanded to markets in Africa, Central and Latin America, and the Middle East.
The company's products are designed to work with existing telecommunications infrastructure to provide low-cost voice and data services for access to both wireless (Wi-Fi) and fixed line products, optimized for mobile backhaul, metro aggregation, broadband access and Wi-Fi data. As of 2015, the company focuses on two core areas: broadband and next-generation network (NGN).
The company has offices worldwide with business and R&D centers located in China, Japan, South Korea, India, the Middle East and Europe. It is listed on the NASDAQ since 2000.
History
The company was founded in 1995 as a merger between Unitech and Starcom Networks to form UTStarcom. Unitech was founded in 1991 by Hong Liang Lu (), a Chinese entrepreneur with a BS degree from UC Berkeley, as Unitech Telecom. It was focused on the telecommunications markets in China, Japan, United States and India, with its initial presence in China established in 1993 in Hangzhou, Zhejiang. Starcom Networks was founded in 1991 by Ying Wu () and a team who had worked together at the Bell Labs in New Jersey, United States.
After several years of trying to expand its business globally, UTStarcom launched the Personal Handy-phone System, also known as the Personal Handy-phone System, a technology originally developed in Japan.
In March 2000, UTStarcom went public on the NASDAQ.
In July 2008, UTStarcom sold its Personal Communications Division to AIG.
References
Telecommunications equipment vendors
Telecommunications companies of Hong Kong
Streaming television
Telecommunications companies established in 1991
Chinese companies established in 1991
Companies listed on the Nasdaq
1991 establishments in China
Telecommunications companies of China
Chinese brands
Companies based in Beijing
Multinational companies headquartered in China
1991 in Beijing | UTStarcom | Technology | 440 |
11,421,344 | https://en.wikipedia.org/wiki/Pestivirus%20internal%20ribosome%20entry%20site%20%28IRES%29 | This family represents the internal ribosome entry site (IRES) of the pestiviruses. The pestivirus IRES allows cap and end-independent translation of mRNA in the host cell. The IRES achieves this by mediating the internal initiation of translation by recruiting a ribosomal 43S pre-initiation complex directly to the initiation codon and eliminates the requirement for the eukaryotic initiation factor, eIF4F. The classical swine fever virus UTR described appears to be longer at the 5' end than other pestivirus UTRs. This family represents the conserved core.
References
External links
Cis-regulatory RNA elements
Internal ribosome entry site | Pestivirus internal ribosome entry site (IRES) | Chemistry | 140 |
578,436 | https://en.wikipedia.org/wiki/Self-medication | Self-medication, sometime called do-it-yourself (DIY) medicine, is a human behavior in which an individual uses a substance or any exogenous influence to self-administer treatment for physical or psychological conditions, for example headaches or fatigue.
The substances most widely used in self-medication are over-the-counter drugs and dietary supplements, which are used to treat common health issues at home. These do not require a doctor's prescription to obtain and, in some countries, are available in supermarkets and convenience stores.
The field of psychology surrounding the use of psychoactive drugs is often specifically in relation to the use of recreational drugs, alcohol, comfort food, and other forms of behavior to alleviate symptoms of mental distress, stress and anxiety, including mental illnesses or psychological trauma. Such treatment may cause serious detriment to physical and mental health if motivated by addictive mechanisms. In postsecondary (university and college) students, self-medication with "study drugs" such as Adderall, Ritalin, and Concerta has been widely reported and discussed in literature.
Products are marketed by manufacturers as useful for self-medication, sometimes on the basis of questionable evidence. Claims that nicotine has medicinal value have been used to market cigarettes as self-administered medicines. These claims have been criticized as inaccurate by independent researchers. Unverified and unregulated third-party health claims are used to market dietary supplements.
Self-medication is often seen as gaining personal independence from established medicine, and it can be seen as a human right, implicit in, or closely related to the right to refuse professional medical treatment. Self-medication can cause unintentional self-harm. Self-medication with antibiotics has been identified as one of the primary reasons for the evolution of antimicrobial resistance.
Sometimes self-medication or DIY medicine occurs because patients disagree with a doctor's interpretation of their condition, to access experimental therapies that are not available to the public, or because of legal bans on healthcare, as in the case of some transgender people or women seeking self-induced abortion. Other reasons for relying on DIY medical care is to avoid health care prices in the United States and anarchist beliefs.
Definition
Generally speaking, self-medication is defined as "the use of drugs to treat self-diagnosed disorders or symptoms, or the intermittent or continued use of a prescribed drug for chronic or recurrent disease or symptoms".
Self-medication can be defined as the use of drugs to treat an illness or symptom when the user is not a medically qualified professional. The term is also used to include the use of drugs outside their license or off-label.
Psychology and psychiatry
Self-medication hypothesis
As different drugs have different effects, they may be used for different reasons. According to the self-medication hypothesis (SMH), the individuals' choice of a particular drug is not accidental or coincidental, but instead, a result of the individuals' psychological condition, as the drug of choice provides relief to the user specific to his or her condition. Specifically, addiction is hypothesized to function as a compensatory means to modulate effects and treat distressful psychological states, whereby individuals choose the drug that will most appropriately manage their specific type of psychiatric distress and help them achieve emotional stability.
The self-medication hypothesis (SMH) originated in papers by Edward Khantzian, Mack and Schatzberg, David F. Duncan, and a response to Khantzian by Duncan. The SMH initially focused on heroin use, but a follow-up paper added cocaine. The SMH was later expanded to include alcohol, and finally all drugs of addiction.
According to Khantzian's view of addiction, drug users compensate for deficient ego function by using a drug as an "ego solvent", which acts on parts of the self that are cut off from consciousness by defense mechanisms. According to Khantzian, drug dependent individuals generally experience more psychiatric distress than non-drug dependent individuals, and the development of drug dependence involves the gradual incorporation of the drug effects and the need to sustain these effects into the defensive structure-building activity of the ego itself. The addict's choice of drug is a result of the interaction between the psychopharmacologic properties of the drug and the affective states from which the addict was seeking relief. The drug's effects substitute for defective or non-existent ego mechanisms of defense. The addict's drug of choice, therefore, is not random.
While Khantzian takes a psychodynamic approach to self-medication, Duncan's model focuses on behavioral factors. Duncan described the nature of positive reinforcement (e.g., the "high feeling", approval from peers), negative reinforcement (e.g. reduction of negative affect) and avoidance of withdrawal symptoms, all of which are seen in those who develop problematic drug use, but are not all found in all recreational drug users. While earlier behavioral formulations of drug dependence using operant conditioning maintained that positive and negative reinforcement were necessary for drug dependence, Duncan maintained that drug dependence was not maintained by positive reinforcement, but rather by negative reinforcement. Duncan applied a public health model to drug dependence, where the agent (the drug of choice) infects the host (the drug user) through a vector (e.g., peers), while the environment supports the disease process, through stressors and lack of support.
Khantzian revisited the SMH, suggesting there is more evidence that psychiatric symptoms, rather than personality styles, lie at the heart of drug use disorders. Khantzian specified that the two crucial aspects of the SMH were that (1) drugs of abuse produce a relief from psychological suffering and (2) the individual's preference for a particular drug is based on its psychopharmacological properties. The individual's drug of choice is determined through experimentation, whereby the interaction of the main effects of the drug, the individual's inner psychological turmoil, and underlying personality traits identify the drug that produces the desired effects.
Meanwhile, Duncan's work focuses on the difference between recreational and problematic drug use. Data obtained in the Epidemiologic Catchment Area Study demonstrated that only 20% of drug users ever experience an episode of drug abuse (Anthony & Helzer, 1991), while data obtained from the National Comorbidity Study demonstrated that only 15% of alcohol users and 15% of illicit drug users ever become dependent. A crucial determinant of whether a drug user develops drug abuse is the presence or absence of negative reinforcement, which is experienced by problematic users, but not by recreational users. According to Duncan, drug dependence is an avoidance behavior, where an individual finds a drug that produces a temporary escape from a problem, and taking the drug is reinforced as an operant behavior.
Specific mechanisms
Some people who have a mental illness attempt to correct their illnesses by using certain drugs. Depression is often self-medicated by the use of alcohol, tobacco, cannabis, or other mind-altering drugs. While this may provide immediate relief of some symptoms such as anxiety, it may evoke and/or exacerbate some symptoms of several kinds of mental illnesses that are already latently present, and may lead to addiction or physical dependency, among other side effects of long-term use of the drug. This does not differ significantly from the potential effects of drugs provided by physicians, which are equally capable of producing dependency and/or addiction and also have side effects arising from long-term use.
People with post-traumatic stress disorder have been known to self-medicate, as well as many individuals without this diagnosis who have experienced psychological trauma.
Due to the different effects of the different classes of drugs, the SMH postulates that the appeal of a specific class of drugs differs from person to person. In fact, some drugs may be aversive for individuals for whom the effects could worsen affective deficits.
CNS depressants
Alcohol and sedative/hypnotic drugs, such as barbiturates and benzodiazepines, are central nervous system (CNS) depressants that lower inhibitions via anxiolysis. Depressants produce feelings of relaxation and sedation, while relieving feelings of depression and anxiety. Though they are generally ineffective antidepressants, as most are short-acting, the rapid onset of alcohol and sedative/hypnotics softens rigid defenses and, in low to moderate doses, provides relief from depressive affect and anxiety. As alcohol also lowers inhibitions, alcohol is also hypothesized to be used by those who normally constrain emotions by attenuating intense emotions in high or obliterating doses, which allows them to express feelings of affection, aggression and closeness. Most patients that have been hospitalized for substance use or alcohol dependence reported using drugs in response to depressive symptoms. This type of misuse is more likely in men than in women. This makes diagnosing a psychiatric disorder very difficult in substance abusers, because of self medicating.
Alcohol
People with social anxiety disorder commonly use alcohol to overcome their highly set inhibitions.
Psychostimulants
Psychostimulants, such as cocaine, amphetamines, methylphenidate, caffeine, and nicotine, produce improvements in physical and mental functioning, including increased energy and alertness. Stimulants tend to be most widely used by people with attention deficit hyperactivity disorder (ADHD), which can either be diagnosed or undiagnosed. Because a significant portion of people with ADHD have not been diagnosed they are more prone to using stimulants like caffeine, nicotine or pseudoephedrine to mitigate their symptoms. Unawareness concerning the effects of illicit substances such as cocaine, methamphetamine or mephedrone can result in self-medication with these drugs by individuals affected with ADHD symptoms. This self medication can effectively prevent them from getting diagnosed with ADHD and receiving treatment with stimulants like methylphenidate and amphetamines.
Stimulants also can be beneficial for individuals who experience depression, to reduce anhedonia and increase self-esteem, however in some cases depression may occur as a comorbid condition originating from the prolonged presence of negative symptoms of undiagnosed ADHD, which can impair executive functions, resulting in lack of motivation, focus and contentment with one's life, so stimulants may be useful for treating treatment-resistant depression, especially in individuals thought to have ADHD. The SMH also hypothesizes that hyperactive and hypomanic individuals use stimulants to maintain their restlessness and heighten euphoria. Additionally, stimulants are useful to individuals with social anxiety by helping individuals break through their inhibitions. Some reviews suggest that students use psychostimulants to self medicate for underlying conditions, such as ADHD, depression or anxiety.
Opiates
Opiates, such as heroin and morphine, function as an analgesic by binding to opioid receptors in the brain and gastrointestinal tract. This binding reduces the perception of and reaction to pain, while also increasing pain tolerance. Opiates are hypothesized to be used as self-medication for aggression and rage. Opiates are effective anxiolytics, mood stabilizers, and anti-depressants, however, people tend to self-medicate anxiety and depression with depressants and stimulants respectively, though this is by no means an absolute analysis.
Modern research into novel antidepressants targeting opioid receptors suggests that endogenous opioid dysregulation may play a role in medical conditions including anxiety disorders, clinical depression, and borderline personality disorder. BPD is typically characterized by sensitivity to rejection, isolation, and perceived failure, all of which are forms of psychological pain. As research suggests that psychological pain and physiological pain both share the same underlying mechanism, it is likely that under the self-medication hypothesis some or most recreational opioid users are attempting to alleviate psychological pain with opioids in the same way opioids are used to treat physiological pain.
Cannabis
Cannabis is paradoxical in that it simultaneously produces stimulating, sedating and mildly psychedelic properties and both anxiolytic or anxiogenic properties, depending on the individual and circumstances of use. Depressant properties are more obvious in occasional users, and stimulating properties are more common in chronic users. Khantzian noted that research had not sufficiently addressed a theoretical mechanism for cannabis, and therefore did not include it in the SMH.
Effectiveness
Self-medicating excessively for prolonged periods of time with benzodiazepines or alcohol often makes the symptoms of anxiety or depression worse. This is believed to occur as a result of the changes in brain chemistry from long-term use. Of those who seek help from mental health services for conditions including anxiety disorders such as panic disorder or social phobia, approximately half have alcohol or benzodiazepine dependence issues.
Sometimes anxiety precedes alcohol or benzodiazepine dependence but the alcohol or benzodiazepine dependence acts to keep the anxiety disorders going, often progressively making them worse. However, some people addicted to alcohol or benzodiazepines, when it is explained to them that they have a choice between ongoing poor mental health or quitting and recovering from their symptoms, decide on quitting alcohol or benzodiazepines or both. It has been noted that every individual has an individual sensitivity level to alcohol or sedative hypnotic drugs, and what one person can tolerate without ill health, may cause another to experience very ill health, and even moderate drinking can cause rebound anxiety syndrome and sleep disorders. A person experiencing the toxic effects of alcohol will not benefit from other therapies or medications, as these do not address the root cause of the symptoms.
Nicotine addiction seems to worsen mental health problems. Nicotine withdrawal depresses mood, increases anxiety and stress, and disrupts sleep. Although nicotine products temporarily relieve their nicotine withdrawal symptoms, an addiction causes stress and mood to be worse on average, due to mild withdrawal symptoms between hits. Nicotine addicts need the nicotine to temporarily feel normal. Nicotine industry marketing has claimed that nicotine is both less harmful and therapeutic for people with mental illness, and is a form of self-medication. This claim has been criticised by independent researchers.
Self medicating is a very common precursor to full addictions and the habitual use of any addictive drug has been demonstrated to greatly increase the risk of addiction to additional substances due to long-term neuronal changes. Addiction to any/every drug of abuse tested so far has been correlated with an enduring reduction in the expression of GLT1 (EAAT2) in the nucleus accumbens and is implicated in the drug-seeking behavior expressed nearly universally across all documented addiction syndromes. This long-term dysregulation of glutamate transmission is associated with an increase in vulnerability to both relapse-events after re-exposure to drug-use triggers as well as an overall increase in the likelihood of developing addiction to other reinforcing drugs. Drugs which help to re-stabilize the glutamate system such as N-acetylcysteine have been proposed for the treatment of addiction to cocaine, nicotine, and alcohol.
Infectious diseases
In 89% of countries, antibiotics can be prescribed only by a doctor and supplied only by a pharmacy. Self-medication with antibiotics is defined as "the taking of medicines on one's own initiative or on another person's suggestion, who is not a certified medical professional". It has been identified as one of the primary reasons for the evolution of antimicrobial resistance.
Self-medication with antibiotics is an unsuitable way of using them but a common practice in developing countries. Many people resort to that out of necessity when access to a physician is unavailable because of lockdowns and GP surgery closures, or when the patients have a limited amount of time or money to see a prescribing doctor. While being cited as an important alternative to a formal healthcare system where it may be lacking, self-medication can pose a risk to both the patient and community as a whole. The reasons behind self-medication are unique to each region and can relate to health system, societal, economic, health factors, gender, and age. Risks include allergies, lack of cure, and even death.
Besides developing countries, self-medication with antibiotics is also a problem for higher-income countries. In the European Union the average prevalence was 7% in 2016 with the highest rates in southern countries. There are high rates of self-medication with antibiotics in Russia (83%), Central America (19%) and Latin America (14-26%) too.
Two significant issues with self-medication are the lack of knowledge of the public on, firstly, the dangerous effects of certain antimicrobials (for example, ciprofloxacin, which can cause tendonitis, tendon rupture and aortic dissection) and, secondly, broad microbial resistance and when to seek medical care if the infection is not clearing.
Also inappropriate use of over-the-counter ibuprofen or other nonsteroidal anti-inflammatory drugs during winter influenza outbreaks can lead to death, e.g. due to haemorrhagic duodenitis induced by ibuprofen, or the consequences of exceeding the recommended doses of paracetamol by combining doses of the generic product with proprietary flu-remedies and Tylex (paracetamol and codeine).
In a questionnaire designed to evaluate self-medication rates amongst the population of Khartoum, Sudan, 48.1% of respondents reported self-medicating with antibiotics within the past 30 days, whereas 43.4% reported self-medicating with antimalarials, and 17.5% reported self-medicating with both. Overall, the total prevalence of reported self-medication with one or both classes of anti-infective agents within the past month was 73.9%. Furthermore, according to the associated study, data indicated that self-medication "varies significantly with a number of socio-economic characteristics" and the "main reason that was indicated for the self-medication was financial constraints".
Similarly, in a survey of university students in southern China, 47.8% of respondents reported self-medicating with antibiotics.
Other uses
One area of DIY medicine is self-administered pharmaceutical drugs that are obtained without a prescription, as in the case of DIY transgender hormone therapy which is common among trans people. Prescription-only lifestyle drugs such as those to treat erectile dysfunction, male pattern baldness, and obesity are often purchased online by people who have no diagnosis or prescription. In 2017, the United Kingdom legalized the sale of sildenafil (Viagra) over the counter in part to cut down on the number of men buying it online from unlicensed pharmacies.
Self-managed abortion with medication is safe and effective, but is illegal in some jurisdictions. Before the current medication had been developed and in places where abortion is illegal, people may resort to unsafe methods of self-managed abortion.
Another area is the creation of medical devices, such as PPE for protection against COVID-19 and epinephrine injectors. Some people with insulin-dependent diabetes have created their own automated insulin delivery systems. One review found that "the quality of glucose control achieved with DIY AID systems is impressively good". With DIY brain stimulation, individuals with depression create their own devices to access an experimental treatment. Other people self-administer fecal transplant as a treatment for various diseases.
Physicians and medical students
In a survey of West Bengal, India undergraduate medical school students, 57% reported self-medicating. The type of drugs most frequently used for self-medication were antibiotics (31%), analgesics (23%), antipyretics (18%), antiulcerics (9%), cough suppressants (8%), multivitamins (6%), and anthelmintics (4%).
Another study indicated that 53% of physicians in Karnataka, India reported self-administration of antibiotics.
Children
A study of Luo children in western Kenya found that 19% reported engaging in self-treatment with either herbal or pharmaceutical medicine. Proportionally, boys were much more likely to self-medicate using conventional medicine than herbal medicine as compared with girls, a phenomenon which was theorized to be influenced by their relative earning potential.
Regulation
Self-medication is highly regulated in much of the world and many classes of drugs are available for administration only upon prescription by licensed medical personnel. Safety, social order, commercialization, and religion have historically been among the prevailing factors that lead to such prohibition.
People trying to buy pharmaceutical drugs online without a prescription may be the victim of fraud, phishing, or receive counterfeit medication. Selling prescription drugs to people without a valid prescription is illegal in many jurisdictions and can be considered an example of transnational organized crime. In a 2021 article, Jack E. Fincham argues that unlicensed sales of prescription drugs online are a significant public health threat. It is also possible to obtain controlled substances such as amphetamine, benzodiazepines, and Z-drugs online without a prescription.
See also
Biodiversity and drugs
Cognitive liberty
Coping
Dual diagnosis
Alcoholism
Emotional eating
Psychedelic microdosing
Zoopharmacognosy
Self-surgery
Self-diagnosis
References
Further reading
External links
Comprehensive Drug Self-administration and Discrimination Bibliographic Databases
Self-medication at Medical Subject Headings
Pharmacy
Addiction
Substance-related disorders
Alcohol and health
Substance dependence
Mood disorders
Anxiety
Psychological stress
DIY medicine
Patient advocacy | Self-medication | Chemistry | 4,500 |
17,988,859 | https://en.wikipedia.org/wiki/Mercury%28I%29%20fluoride | Mercury(I) fluoride or mercurous fluoride is the chemical compound composed of mercury and fluorine with the formula Hg2F2. It consists of small yellow cubic crystals, which turn black when exposed to light.
Synthesis
Mercury(I) fluoride is prepared by the reaction of mercury(I) carbonate with hydrofluoric acid:
Hg2CO3 + 2 HF → Hg2F2 + CO2 + H2O
Reactions
When added to water, mercury(I) fluoride hydrolyzes to elemental liquid mercury, mercury(II) oxide, and hydrofluoric acid:
Hg2F2 + H2O → Hg + HgO + 2 HF
It can be used in the Swarts reaction to convert alkyl halides into alkyl fluorides:
2 R-X + Hg2F2 → 2 R-F + Hg2X2
where X = Cl, Br, I
Structure
In common with other Hg(I) (mercurous) compounds which contain linear X-Hg-Hg-X units, Hg2F2 contains linear FHg2F units with an Hg-Hg bond length of 251 pm (Hg-Hg in the metal is 300 pm) and an Hg-F bond length of 214 pm. The overall coordination of each Hg atom is a distorted octahedron; in addition to the bonded F and other Hg of the molecule, there are four other F atoms at 272 pm. The compound is often formulated as .
References
Mercury(I) compounds
Fluorides
Metal halides
Chemical compounds containing metal–metal bonds | Mercury(I) fluoride | Chemistry | 351 |
3,931,871 | https://en.wikipedia.org/wiki/Code%20morphing | Code morphing is an approach used in obfuscating software to protect software applications from reverse engineering, analysis, modifications, and cracking. This technology protects intermediate level code such as compiled from Java and .NET languages (Oxygene, C#, Visual Basic, etc.) rather than binary object code. Code morphing breaks up the protected code into several processor commands or small command snippets and replaces them by others, while maintaining the same end result. Thus the protector obfuscates the code at the intermediate level.
Code morphing is a multilevel technology containing hundreds of unique code transformation patterns. In addition this technology transforms some intermediate layer commands into virtual machine commands (like p-code). Code morphing does not protect against runtime tracing, which can reveal the execution logic of any protected code.
Unlike other code protectors, there is no concept of code decryption with this method. Protected code blocks are always in the executable state, and they are executed (interpreted) as transformed code. The original intermediate code is absent to a certain degree, but deobfuscation can still give a clear view of the original code flow.
Code morphing is also used to refer to the just-in-time compilation technology used in Transmeta processors such as the Crusoe and Efficeon to implement the x86 instruction set architecture.
Code morphing is often used in obfuscating the copy protection or other checks that a program makes to determine whether it is a valid, authentic installation, or an unauthorized copy, in order to make the removal of the copy-protection code more difficult than would otherwise be the case.
See also
Intermediate language
References
Software obfuscation
Source code
Warez | Code morphing | Technology,Engineering | 357 |
18,715,443 | https://en.wikipedia.org/wiki/Robin%20Farquharson | Reginald Robin Farquharson (3 October 1930 – 1 April 1973) was an academic whose interest in mathematics and politics led him to work on game theory and social choice theory. He wrote an influential analysis of voting systems in his doctoral thesis, later published as Theory of Voting, and conjectured the Gibbard–Satterthwaite theorem together with the philosopher and logician Michael Dummett.
Farquharson diagnosed himself as suffering from bipolar disorder (manic depression), and episodes of mania made it difficult for him to obtain a permanent university position and also resulted in him losing commercial employment. In later years, he dropped out of mainstream society, and became a prominent counter-cultural figure in late-1960s London. Farquharson wrote an account of his unconventional life in his 1968 book, Drop Out!, in which he described a week of being homeless in London.
In 1973 he died from burns associated with an arson, for which two persons were convicted of unlawful killing.
Education
Robin Farquharson was educated at Michaelhouse, Natal, South Africa, 1944–46. He earned a B.A. in South Africa from Rhodes University College, Grahamstown (1947–50). Subsequently studying at Brasenose and Nuffield Colleges, University of Oxford (1950–53), he obtained a second-class B.A. honours PPE degree. For his B.A. 1953–54 (?), his studies at this time were overseen by David Butler of Nuffield College, Oxford University. His D.Phil. was awarded in June 1958 from Nuffield College for his thesis entitled "An Approach to a Pure Theory of Voting Procedures".
He was given a Research Fellowship at Churchill College, Cambridge in 1964. He also studied at the Sorbonne in Paris.
While an undergraduate at Oxford, Farquharson was a contemporary of John Searle, Rupert Murdoch, and Sir Michael Dummett.
Research on voting
Farquharson wrote a monograph on the analysis of voting procedures and several papers, including a notable paper with Michael Dummett that conjectured the Gibbard–Satterthwaite theorem.
Strategic voting
Farquharson published influential articles on the theory of voting: in particular, in an article with Michael Dummett, he conjectured that deterministic voting rules with more than three issues faced endemic strategic voting. The Dummett–Farquharson conjecture was proved by Allan Gibbard, a philosopher and former student of Kenneth J. Arrow and John Rawls, and by Mark Satterthwaite, an economist.
After the establishment of the Farquarson-Dummett conjecture by Gibbard and Sattherthwaite, Michael Dummett contributed three proofs of the Gibbard–Satterthwaite theorem in his monograph on voting.
Theory of Voting
In the field of political game theory, Farquharson's main contribution was his exposition of the Condorcet paradox regarding the sincerity of voters. The problem was initially raised by Pliny the Younger and then picked up again in the political pamphlets of Reverend Charles Lutwidge Dodgson (Lewis Carroll), who was a significant influence on Farquharson.
Theory of Voting was originally Farquharson's doctoral thesis but was deemed to be of such a high quality it was later published as a book in its own right. Although written in 1958, when his doctorate was awarded, it was eventually published in 1969, by Yale University Press. The main reason given for the delay in publication is that Farquharson insisted that the logical choice diagrams be printed in colour, which they eventually were, in black, white and red.
The book won the Monograph Prize in the field of Social Sciences, awarded by the American Academy of Arts and Sciences.
Mental illness
At some point, Farquharson came to diagnose himself as suffering from several mental illnesses including bipolar disorder (manic depression) and cyclothymia. His condition caused him to be absent frequently from his university studies, starting November 1955 to March 1957. He was further absent from his studies after the death of his father.
Call to the Warden of All Souls College
As Michael Dummett recalls, in 1955 Farquharson sat the Fellowship examination for All Souls College. On the evening before an election meeting was held to discuss Farquharson's admission as a Fellow, the Warden of the college received a telephone call, which started with the words: "Do you have a pen and paper?" Farquharson tried to dictate what Dummett describes (he was not present himself) as a "lengthy statement in quasi-technical language, expounding a discovery in which would have solve [sic] many problems in mathematics, mathematical logic, physics, economics and the theory of voting."
Dummett's clarifies the accuracy of his recollection: "I know very well what it was like: though I was away for the year in California, Farquharson also telephoned me there in just the same manner."
Farquharson was undergoing an attack of his mental illness, which it is believed caused him to contact the College Warden.
Dummett believes that Farquharson was far and above the best candidate for the election to the college; however, the Warden chose to mention Farquharson's telephone call to the Fellows, and Dummett believes the Warden "...inferred that Farquharson had gone mad", which no doubt led to his not being elected to the senior position of Fellow at All Souls College.
Farquharson briefly describes the incident in Drop Out!: "...when as a candidate for a Fellowship of All Souls, I had destroyed my chances by a telephone call to the Warden, calling him from his high table to tell him that I had a message from God for him."
Mental health activism
After fully dropping out Farquharson did some work supporting the mental health patient reform groups of the late 1960s, working with organisations such as the Mental Patients' Union. He wrote, campaigned and argued with other members of the group for mental patients to have a greater say in their own treatment. He also helped to secure squatted sites and rent houses for groups to hold meetings and simply for a place to live.
Farquharson was a mental health activist working both with Tommie Ritchie in the Scottish Union of Mental Patients (SUMP) during 1972 and then the Mental Patients Union in 1973, shortly before his death.
He was the first member of SUMP from outside Hartwood Hospital.
Later life and work
After being rejected from a prospective Fellowship at All Souls College, Oxford, Farquharson worked for a brief time as an academic at Cambridge University. After losing this job he worked in various other administrative positions, including as a manager for a call centre. He also contributed to the counter-cultural Bitman magazine, which published a special obituary edition as a tribute to him after his death in 1973.
His friend Guy Legge, who knew him from his time in Horton Hospital, thought Robin was an alcoholic and blames his wild mood swings on his dependency.
Autobiographical Drop Out!
Dropping out commonly refers to a person who has left an educational institution without completing the course. This does not apply in the same way to Robin Farquharson, who held several degrees. The title of his book more accurately refers to his dropping out from the comfort of academic life into the uncertainty of London street-life.
The book begins with a quote from a poem by Matthew Arnold:
We cannot kindle when we will
The fire which in the heart resides,
The spirit bloweth and is still,
In mystery our soul abides:
But tasks in hours of insight willed
Can be through hours of gloom fulfilled.
– Matthew Arnold, "Morality".
Essentially the book is an account of Farquharson finding himself homeless and with little money and many debts to claim, both through circumstance and his own actions. In an experimental spirit he attempts to forsake money (several times and with varying success) as a kind of restrictive social evil. This leaves him with very little option but to sleep rough and stay with friends or acquaintances now and again. The book includes a chapter on the free help offered by Rhaune Laslett and the Notting Hill Neighbourhood Service.
Many people see the book as a slightly forced and therefore somewhat un-genuine attempt to slum it with the lower classes in that Robin is so often bailed out by either good fortune, the kindness of strangers or old friends. It is much easier to step into a life of destitution like a puddle and to briskly leave it if the water becomes too cold knowing that there is money behind you and lots of people who are prepared to help you, for a short while at least.
The book is similar in style and content to other works of psycho-geography written by the situationists. Many sections of the book simply list the areas of London Farquharson has walked through, including the names of streets and buildings he passes, interspersed with events and acquaintances he makes along the way.
It is the flux of his mental state and the variety of situations he encounters that make the book an interesting and vibrant account of London in the late-1960s. He copies information on a notice board, and rates graffiti in a public toilet for spelling, grammar and general interest.
Political activity
In 1965 Farqharson's South African passport was revoked as a result of his part in the lobbying, on behalf of SAN-ROC, for South Africa's exclusion from the Olympic Games held in Tokyo, Japan, in 1964. He was rumoured to have been a member of the political White Panther movement.
He became a British subject in 1968.
He is also said to have helped tear down the walls at the Isle of Wight Festival 1970.
The squat years
Towards the end of his life Farquharson spent much of his time in "open-university" squat communities, a period during which he met artists and thinkers, including the poet Aidan Andrew Dun and the psychiatrist R. D. Laing.
Death
Farquharson died as the result of a fire at a house in Platt Street, Somers Town, London, in April 1973, down the road from St Pancras Old Church. After being exposed to the fire, Farquharson suffered third-degree burns. He was taken to the Hospital for Tropical Diseases near to St Pancras churchyard, where he died from his burns. Two workers also living in the house were tried for his death and found guilty of "unlawful killing".
In popular culture
Iain Sinclair, Lights Out for the Territory
References
Bibliography
Academics of the University of Cambridge
1930 births
1973 deaths
Counterculture
Alumni of Nuffield College, Oxford
People with bipolar disorder
20th-century squatters
Deaths from fire
Game theorists
Voting theorists
Rhodes University alumni
South African emigrants to the United Kingdom
Alumni of Michaelhouse
Alumni of Brasenose College, Oxford | Robin Farquharson | Mathematics | 2,244 |
53,609,258 | https://en.wikipedia.org/wiki/Taurob%20tracker | Taurob tracker is a mobile robot, manufactured by Taurob GmbH in Austria. It has been originally developed as a remote controlled reconnaissance platform for fire departments.
but is currently used also by the military, civil-defense units, universities and the oil and gas industry around the world.
Since 2013 an ATEX Zone 1 certified variant, called Taurob Tracker Ex is available, which is able to drive in explosive atmospheres safely.
A taurob tracker version with sensors for environments with extreme smoke (e.g. fires in tunnels or subway stations) is currently being developed in the EU funded "SmokeBot" project
Specifications
Track assembly
Compared to most other mobile robots, the taurob tracker has a unique track geometry which allows it to climb over obstacles with just one pair of tracks. Due this geometry the tracks do not lose their tension when raising or lowering the front wheels. Further advantages include improved traction (thus the name of the robot) on uneven ground and a rapid track exchange mechanism.
Notable appearances
In 2016 a taurob tracker platform was used in the RoboCup Rescue League by team Hector.
In 2017 a variant of taurob tracker called "Argonaut" has won the ARGOS Challenge organised by Total Energies. It is the first fully autonomous, ATEX certified mobile inspection robot for Oil and Gas installations. According to Total it will be used on their industrial sites by 2020.
References
Robotics | Taurob tracker | Engineering | 288 |
62,724,737 | https://en.wikipedia.org/wiki/Lactarius%20adscitus | Lactarius adscitus is a member of the large milk-cap genus Lactarius in the order Russulales. The species was first described in 1885 by German mycologist Max Britzelmayr.
See also
List of Lactarius species
References
External links
adscitus
Fungi described in 1885
Taxa named by Max Britzelmayr
Fungus species | Lactarius adscitus | Biology | 74 |
12,543,376 | https://en.wikipedia.org/wiki/Oleandomycin | Oleandomycin is a macrolide antibiotic. It is synthesized from strains of Streptomyces antibioticus. It is weaker than erythromycin.
It used to be sold under the brand name Sigmamycine, combined with tetracycline, and made by the company Rosa-Phytopharma in France.
Medical uses
Oleandomycin inhibits the bacteria responsible for upper respiratory tract infections. Its spectrum of activity includes bacteria in the Staphylococcus and Enterococcus genera.
The MIC for oleandomycin is 0.3-3 μg/mL for Staphylococcus aureus.
Oleandomycin is approved as a veterinary antibiotic in some countries.
It has been approved as a swine and poultry antibiotic in the United States. However, it is currently only approved in the United States for production uses.
Pharmacology
Mechanism of action
Oleandomycin is a bacteriostatic agent. Like erythromycin, oleandomycin binds to the 50s subunit of bacterial ribosomes, inhibiting the completion of proteins vital to survival and replication.
It interferes with translational activity but also with 50s subunit formation.
However, unlike erythromycin and its effective synthetic derivatives, it lacks a 12-hydroxyl group and a 3-methoxy group. This change in structure may adversely affect its interactions with 50S structures and explain why it is a less powerful antibiotic.
Relative strength
Oleandomycin is far less effective than erythromycin in bacterial minimum inhibitory concentration tests involving staphylococci or enterococci.
However, macrolide antibiotics can accumulate in organs or cells and this effect can prolong the bioactivity of this category of antibiotics even if its concentration in plasma is below what is considered capable of a therapeutic effect.
Chemistry
Polyketide biosynthesis
The oleandomycin synthase (OLES) follows the module structure of a type I synthase. The polyketide chain is bound through thioester linkages to the S-H groups of the ACP and KS domains
The gene cluster OLES1 codes for modules 0-2, module 0 containing an acetyl-CoA starter unit and all remaining moduless carrying a methyl malonyl-CoA elongation unit attached to its keto synthase unit.
OLES2 codes for modules 3 and 4. Module 3 is notable for potentially carrying a redox-inactive ketoreductase that is responsible for retaining the unreduced carbonyl adjacent to carbon 8.
OLES3 codes for modules 5 and 6.
The amino acid sequence similarities between OLES and 6-Deoxyerythronolide B synthase (erythromycin precursor synthase) show only a 45% common identity. Note that unlike in the erythromycin precursor synthase, there is a KS in the loading domain of OLES.
Post-PKS modifications
The genes OleG1 and G2 are responsible for the glycosyltransferases that attach oleandomycin's characteristic sugars to the macrolide. These sugars are derived from TDP-glucose. OLEG1 transfers dTDP-D-desoamine and OleG2 transfers D-TDP-L-oleandrose to the macrolide ring. The epoxidation that occurs afterwards is from the enzyme encoded by OleP, which could be homologous with a P450 enzyme. The method by which OleP epoxidates is suspected to be a dihydroxylation followed by the conversion of a hydroxyl group into a phosphate group that then leaves via a nucleophilic ring closure by the other hydroxyl group.
History
Oleandomycin was first discovered as a product of the bacterium Streptomyces antibioticus in 1954 by Dr. Sobin, English, and Celmer. In 1960, Hochstein successfully managed to determine the structure of oleandomycin. This macrolide was discovered at around the same time as its relatives erythromycin and spiramycin.
Sigmamycine combination drug
Public interest in oleandomycin peaked when Pfizer introduced the combination drug Sigmamycine into the market in 1956. Sigmamycine was a combination drug of oleandomycin and tetracycline that was supported by a major marketing campaign. It was in fact claimed that a 2:1 mixture of tetracycline and oleandomycin had a synergistic effect on staphylococci. It was also claimed that the mixture would be effective on organisms that are mostly resistant to tetracycline or oleandomycin alone. Both of these claims were refuted by findings such as those by Lawrence P. Garrod that could find no evidence that such claims were properly substantiated. By the early 1970s, Pfizer's combination drugs were withdrawn from the market.
Society and culture
Brand names
Mastalone – Oleandomycin, oxatetracycline, neomycin – Zoetis Australia and Pfizer Animal Health
Mastiguard – Oleandomycin, oxatetracycline – Stockguard Animal Health
Formerly sold as Sigmamycine by Pfizer (Oleandomycin + Tetracycline + Vitamin C)
References
Macrolide antibiotics
Spiro compounds
Epoxides | Oleandomycin | Chemistry | 1,122 |
167,803 | https://en.wikipedia.org/wiki/Bartholin%27s%20gland | The Bartholin's glands (named after Caspar Bartholin the Younger; also called Bartholin glands or greater vestibular glands) are two pea-sized compound alveolar glands located slightly posterior and to the left and right of the opening of the vagina. They secrete mucus to lubricate the vagina.
They are homologous to bulbourethral glands in males. However, while Bartholin's glands are located in the superficial perineal pouch in females, bulbourethral glands are located in the deep perineal pouch in males. Their duct length is 1.5 to 2.0 cm and they open into navicular fossa. The ducts are paired and they open on the surface of the vulva.
Structure
The embryological origin of the Bartholin's glands is derived from the urogenital sinus; therefore, the innervation and blood supply are via the pudendal nerve and external pudendal artery, respectively. The superficial inguinal lymph nodes and pelvic nodes provide lymphatic drainage.
These glands are pea-sized (0.5–1.0 cm) and are lined with columnar epithelium. The duct length is 1.5–2 cm and is lined with squamous epithelium. These are located just beneath the fascia and their ducts drain into the vestibular mucosa. These mucoid alkaline secreting glands are arranged as lobules consisting of alveoli lined by cuboidal or columnar epithelium. Their efferent ducts are composed of transitional epithelium, which merges into squamous epithelium as it enters the distal vagina. The more proximal portions of the ductal system are lined by transitional epithelium and may be lined by columnar epithelium before arborization into glandular secretory elements.
These glands lie on the perineal membrane and beneath the bulbospongiosus muscle at the tail end of the vestibular bulb deep to the posterior labia majora. The intimate relation between the enormously vascular tissue of the vestibular bulb and the Bartholin's glands is responsible for the risk of hemorrhage associated with the removal of this latter structure.
The openings of the Bartholin's glands are located on the posterior margin of the introitus bilaterally in a groove between the hymen and the labium minus at the 4:00 and 8:00 o'clock positions. The glands duct opening is seen on the posterolateral aspect of the vestibule 3 to 4 mm outside the hymen or hymenal caruncles lateral to the hymenal ring.
History
Bartholin's glands were first described in 1677 by the 17th-century Danish anatomist Caspar Bartholin the Younger (1655–1738).
Earlier he jointly discovered the glands in cows with Joseph Guichard Duverney (1648-1730), a French anatomist.
Some sources mistakenly ascribe their discovery to his grandfather, theologian and anatomist Caspar Bartholin the Elder (1585–1629).
Function
Bartholin's glands secrete mucus to provide vaginal lubrication during sexual arousal. The fluid may slightly moisten the labial opening of the vagina, serving to make contact with this sensitive area more comfortable. Fluid from the Bartholin's glands is combined with other vaginal secretions as a "lubrication fluid" in the amount of about 6 grams per day, and contains high potassium and low sodium concentrations relative to blood plasma, with a slightly acidic pH of 4.7.
Clinical pathology
It is possible for the Bartholin's glands to become blocked and inflamed resulting in pain. This is known as bartholinitis or a Bartholin's cyst. A Bartholin's cyst in turn can become infected and form an abscess. Adenocarcinoma of the gland is rare and benign tumors and hyperplasia are even more rare. Bartholin gland carcinoma is a rare malignancy that occurs in 1% of vulvar cancers. This may be due to the presence of three different types of epithelial tissue. Inflammation of the Skene's glands and Bartholin glands may appear similar to cystocele.
Other animals
The major vestibular glands are found in many mammals such as cats, cows, and some sheep.
See also
List of distinct cell types in the adult human body
List of related male and female reproductive organs
Mesonephric duct
Skene's gland
References
Glands
Exocrine system
Human female reproductive system
Mammal female reproductive system
Anatomy named for one who described it
Sex organs | Bartholin's gland | Biology | 1,005 |
37,272,315 | https://en.wikipedia.org/wiki/Marine%20Biology%20%28journal%29 | Marine Biology is a peer-reviewed scientific journal covering research on all aspects of marine biology. The journal was established in 1967 and is published monthly by Springer Science+Business Media. The editor-in-chief is Ulrich Sommer (Helmholtz Centre for Ocean Research). According to the Journal Citation Reports, the journal has a 2014 impact factor of 2.391.
References
External links
Biology journals
Springer Science+Business Media academic journals
English-language journals
Academic journals established in 1967
Marine biology
Monthly journals
Hybrid open access journals | Marine Biology (journal) | Biology | 106 |
14,446,159 | https://en.wikipedia.org/wiki/GPR111 | Probable G-protein coupled receptor 111 is a protein that in humans is encoded by the GPR111 gene.
References
Further reading
G protein-coupled receptors | GPR111 | Chemistry | 33 |
46,265,020 | https://en.wikipedia.org/wiki/Pepper%20%28cryptography%29 | In cryptography, a pepper is a secret added to an input such as a password during hashing with a cryptographic hash function. This value differs from a salt in that it is not stored alongside a password hash, but rather the pepper is kept separate in some other medium, such as a Hardware Security Module. Note that the National Institute of Standards and Technology refers to this value as a secret key rather than a pepper. A pepper is similar in concept to a salt or an encryption key. It is like a salt in that it is a randomized value that is added to a password hash, and it is similar to an encryption key in that it should be kept secret.
A pepper performs a comparable role to a salt or an encryption key, but while a salt is not secret (merely unique) and can be stored alongside the hashed output, a pepper is secret and must not be stored with the output. The hash and salt are usually stored in a database, but a pepper must be stored separately to prevent it from being obtained by the attacker in case of a database breach. A pepper should be long enough to remain secret from brute force attempts to discover it (NIST recommends at least 112 bits).
History
The idea of a site- or service-specific salt (in addition to a per-user salt) has a long history, with Steven M. Bellovin proposing a local parameter in a Bugtraq post in 1995. In 1996 Udi Manber also described the advantages of such a scheme, terming it a secret salt. The term pepper has been used, by analogy to salt, but with a variety of meanings. For example, when discussing a challenge-response scheme, pepper has been used for a salt-like quantity, though not used for password storage; it has been used for a data transmission technique where a pepper must be guessed; and even as a part of jokes.
The term pepper was proposed for a secret or local parameter stored separately from the password in a discussion of protecting passwords from rainbow table attacks. This usage did not immediately catch on: for example, Fred Wenzel added support to Django password hashing for storage based on a combination of bcrypt and HMAC with separately stored nonces, without using the term. Usage has since become more common.
Types
There are multiple different types of pepper:
A secret unique to each user.
A shared secret that is common to all users.
A randomly-selected number that must be re-discovered on every password input.
Algorithm
An incomplete example of using a pepper constant to save passwords is given bellow.
This table contains two combinations of username and password. The password is not saved, and the 8-byte (64-bit) 44534C70C6883DE2 pepper is saved in a safe place separate from the output values of the hash.
Unlike the salt, the pepper does not provide protection to users who use the same password, but protects against dictionary attacks, unless the attacker has the pepper value available. Since the same pepper is not shared between different applications, an attacker is unable to reuse the hashes of one compromised database to another. A complete scheme for saving passwords usually includes both salt and pepper use.
Shared-secret pepper
In the case of a shared-secret pepper, a single compromised password (via password reuse or other attack) along with a user's salt can lead to an attack to discover the pepper, rendering it ineffective. If an attacker knows a plaintext password and a user's salt, as well as the algorithm used to hash the password, then discovering the pepper can be a matter of brute forcing the values of the pepper. This is why NIST recommends the secret value be at least 112 bits, so that discovering it by exhaustive search is intractable. The pepper must be generated anew for every application it is deployed in, otherwise a breach of one application would result in lowered security of another application. Without knowledge of the pepper, other passwords in the database will be far more difficult to extract from their hashed values, as the attacker would need to guess the password as well as the pepper.
A pepper adds security to a database of salts and hashes because unless the attacker is able to obtain the pepper, cracking even a single hash is intractable, no matter how weak the original password. Even with a list of (salt, hash) pairs, an attacker must also guess the secret pepper in order to find the password which produces the hash. The NIST specification for a secret salt suggests using a Password-Based Key Derivation Function (PBKDF) with an approved Pseudorandom Function such as HMAC with SHA-3 as the hash function of the HMAC. The NIST recommendation is also to perform at least 1000 iterations of the PBKDF, and a further minimum 1000 iterations using the secret salt in place of the non-secret salt.
Unique pepper per user
In the case of a pepper that is unique to each user, the tradeoff is gaining extra security at the cost of storing more information securely. Compromising one password hash and revealing its secret pepper will have no effect on other password hashes and their secret pepper, so each pepper must be individually discovered, which greatly increases the time taken to attack the password hashes.
See also
Salt (cryptography)
HMAC
passwd
References
External links
Cryptography
Password authentication | Pepper (cryptography) | Mathematics,Engineering | 1,101 |
58,507,643 | https://en.wikipedia.org/wiki/Aspergillus%20neocarnoyi | Aspergillus neocarnoyi is a species of fungus in the genus Aspergillus. It is from the Aspergillus section. The species was first described in 1989. It has been reported to produce asperentins, asperflavin, auroglaucin, a bisanthron, dihydroauroglaucin, echinulins, flavoglaucin, neoechinulins, questin, questinol, tetracyclic, and tetrahydroauroglaucin.
Growth and morphology
A. neocarnoyi has been cultivated on both Czapek yeast extract agar (CYA) plates and Malt Extract Agar Oxoid® (MEAOX) plates. The growth morphology of the colonies can be seen in the pictures below.
References
neocarnoyi
Fungi described in 1989
Fungus species | Aspergillus neocarnoyi | Biology | 186 |
7,270,080 | https://en.wikipedia.org/wiki/Chlorinated%20paraffins | Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes (paraffin wax). The chlorination degree of CPs can vary between 30 and 70 wt%. CPs are subdivided according to their carbon chain length into short-chain CPs (SCCPs, C10–13), medium-chain CPs (MCCPs, C14–17) and long-chain CPs (LCCPs, C>17). Depending on chain length and chlorine content, CPs are colorless or yellowish liquids or solids.
Production
Chlorinated paraffins are synthesized by reaction of chlorine gas with unbranched paraffin fractions (<2 % isoparaffins, <100 ppm aromatics) at a temperature of 80–100 °C. The radical substitution may be promoted by UV-light.
CxH(2x+2) + y Cl2 → CxH(2x−y+2)Cly + y HCl
When the desired degree of chlorination is achieved, residues of hydrochloric acid and chlorine are blown off with nitrogen. Epoxidized vegetable oil, glycidyl ether or organophosphorous compounds may be added to the final product for improved stability at high temperatures.
Commercial products have been classified as substances of unknown or variable composition. CPs are complex mixtures of chlorinated n-alkanes containing thousands of homologues and isomers which are not completely separated by standard analytical methods.
CPs are produced in Europe, North America, Australia, Brazil, South Africa and Asia. In China, where most of the world production capacity is located, 600,000 tons of chlorinated paraffins were produced in 2007. Production and use volumes of CPs exceeded 1,000,000 tons in 2013.
Industrial applications
Production of CPs for industrial use started in the 1930s, with global production in 2000 being about 2 million tonnes. Currently, over 200 CP formulations are in use for a wide range of industrial applications, such as flame retardants and plasticisers, as additives in metal working fluids, in sealants, paints, adhesives, textiles, leather fat and coatings.
Safety
Short-chain CPs are classified as persistent and their physical properties (octanol-water partition coefficient (logKOW) 4.4–8, depending on the chlorination degree) imply a high potential for bioaccumulation. SCCPs are classified as toxic to aquatic organisms, and carcinogenic to rats and mice. Therefore, it was concluded that SCCPs have PBT and vPvB properties and they were added to the Candidate List of substances of very high concern for Authorisation under REACH Regulation. SCCPs (average chain length of C12, chlorination degree 60 wt%) were categorised in group 2B as possibly carcinogenic to humans from the International Agency for Research on Cancer (IARC). In 2017, it was agreed to globally ban SCCPs under the Stockholm Convention on Persistent Organic Pollutants, effective December 2018. However, also MCCPs are toxic to the aquatic environment and persistent; MCCPs in soil, biota, and most of the sediment cores show increasing time trends over the last years to decades; MCCP concentrations in sediment close to local sources exceed toxicity thresholds such as the PNEC. In July 2021 also MCCPs were added to the Candidate List of Substances of Very High Concern (SVHC) under the REACH Regulation.
Chlorinated paraffins have been detected in marine life such as cetaceans (whales) and bivalves (molluscs). Of particular concern is fetal accumulation in whales, with the chemicals beginning to build-up in the offspring before they are even born.
References
Sources
Further reading
European Chemicals Bureau (2000). European Union Risk assessment report Vol. 4: Alkanes, C10-13, chloro, Luxembourg: Office for Official Publications of the European Community.
European Chemicals Bureau (2008). European Union Risk assessment report Vol. 81: Alkanes, C10-13, chloro (update), Luxembourg: Office for Official Publications of the European Community.
European Chemicals Bureau (2005). European Union Risk assessment report Vol. 58: Alkanes, C14-17, chloro (MCCP), Part I-Environment, Luxembourg: Office for Official Publications of the European Community.
European Commission (2011). European Union Risk assessment report: Alkanes, C14-17, chloro; Addendum to the final report (2007) of the risk assessment – Environment part. Luxembourg: Office for Official Publications of the European Community.
European Commission (2011). European Union Risk assessment report: Alkanes, C14-17, chloro (MCCP), Part II-Human Health, Luxembourg: Office for Official Publications of the European Community.
External links
Short Chain Chlorinated Paraffins – Proposal for identification of a substance as a CMR, PBT, vPvB or a substance of an equivalent level of concern
Chloroalkanes
Flame retardants
IARC Group 2B carcinogens
Soil contamination | Chlorinated paraffins | Chemistry,Environmental_science | 1,092 |
22,533,334 | https://en.wikipedia.org/wiki/RAJ%20Pharma | The Regulatory Affairs Journal Pharma (RAJ Pharma) is an English language international pharmaceutical information and analysis service published by Informa plc. First published as a monthly print magazinel in 1992, it includes articles covering worldwide regulatory affairs within the pharmaceutical industry. The journal has now developed into an online global business intelligence and analysis service. It provides daily news and analysis of developments in regulation of the pharmaceutical industry worldwide, including regulatory agencies and legislation, application requirements and guidelines, patents and intellectual property, research and development, international harmonisation, paediatric legislation, pharmacovigilance and pharmacoeconomics.
Articles are written by a four-person in-house editorial team, sourced from locally based correspondents from around the world, and independent contributors from legal firms, pharmaceutical companies and regulatory agencies. The RAJ Pharma editorial board comprises a range of regulatory experts from industry and agencies alike.
RAJ Devices
A sister publication, RAJ Devices, covers regulatory affairs within the medical technology industry. It was established in 1995.
References
External links
RAJPharma.com RAJ Pharma homepage
RAJDevices.com RAJ Devices homepage
Business magazines published in the United Kingdom
Monthly magazines published in the United Kingdom
Legal magazines
Magazines published in London
Magazines established in 1992
Pharmaceutical industry | RAJ Pharma | Chemistry,Biology | 258 |
40,014,265 | https://en.wikipedia.org/wiki/Mad%20About%20Physics | Mad about Physics: Brainteasers, Paradoxes, and Curiosities is a book revolving around physics puzzles first released in 2001 and published by Wiley.
It covers mechanics, electricity, magnetism and optics, as well as the physics of sports, space exploration and astronomy. It has been translated into seven languages, including German, Greek, Japanese and Chinese. The book is in its 10th reprinting as of 2013.
Content
The book contains around 400 questions, along with many marginalia, jokes, anecdotes, and scientific facts. It also contains some quotations from Albert Einstein and the cartoon character Bugs Bunny congruent to the theme of the book.
Reception and Reviews
Peter Ford, a physicist at the University of Bath in the UK, called Mad about Physics "an interesting new book." He wrote that "many of its problems will be useful for teachers, both at senior level in schools and at universities, for discussion with students in small groups. Such tutorials should be used to encourage students to start talking about physics and 'thinking like a physicist.'"
Carol Ryback wrote, "Here's a quick fix for those brain-teasing inquiries that stick in your mind like an old song. While not limited to astronomy-related trivia, 'Mad about Physics"—like a top-40 countdown on the radio – has an allure that makes you want more."
Awards
In 2002, Mad about Physics was selected by the New York Public Library as "one of the best" titles of the year 2001 in the teen books and media category.
See also
Cognitive dissonance
Paradox
References
External links
New York Public Library (link to NYPL's list of best 2001 titles in teen books and media)
Popular physics books
Astronomy books
2001 non-fiction books | Mad About Physics | Astronomy | 362 |
33,991,160 | https://en.wikipedia.org/wiki/Coffee%20furanone | Coffee furanone (2-methyltetrahydrofuran-3-one) is a pleasant smelling liquid furan derivative which is a volatile constituent of the aroma complex of roasted coffee. Coffee furanone is less odorous than furfuryl mercaptan, which with an odor threshold of 0.005 ppb was the first high impact aroma chemical, but has a very pleasant sweet caramel character, with some nuttiness.
Synthesis
Coffee furanone was synthesized in 1963 by Wynberg via acid-catalyzed ring closure of β-alkoxy diazoketones. Coffee furanone has also been prepared via the condensation of ethyl lactate and methyl acrylate in DMSO solution and (under phase transfer conditions) in ionic liquids. A related lactic acid synthesis was described as having the advantages of a simple process, high conversion rate, low pollution, and low cost. This compound has also been prepared in acceptable yield via oxidative hydroxylation of the 2-acetylbutyrolactone. Further approaches to the synthesis of coffee furanone involved the hydrolysis of the corresponding dithioketals and the oxidation of 2-methyltetrahydrofuran employing lithium hypochlorite in the presence of ruthenium catalysts.
Applications
The synthetic version of this natural flavorant and odorant is used in a variety of food and beverage applications, including coffee, nuts, cocoa, brandy, meat sauces and as a general food flavorant at a typical dosage (about 5-20 ppm), similar to the natural concentration (30 ppm) of coffee furanone in roasted coffee.
References
Tetrahydrofurans
Ketones | Coffee furanone | Chemistry | 357 |
4,641,155 | https://en.wikipedia.org/wiki/Degree%20of%20unsaturation | In the analysis of the molecular formula of organic molecules, the degree of unsaturation (DU) (also known as the index of hydrogen deficiency (IHD), double bond equivalents (DBE), or unsaturation index) is a calculation that determines the total number of rings and π bonds. A formula is used in organic chemistry to help draw chemical structures. It does not give any information about those components individually—the specific number of rings, or of double bonds (one π bond each), or of triple bonds (two π bonds each). The final structure is verified with use of NMR, mass spectrometry and IR spectroscopy, as well as qualitative inspection. It is based on comparing the actual molecular formula to what would be a possible formula if the structure were saturated—having no rings and containing only σ bonds—with all atoms having their standard valence.
General formula
The formula for degree of unsaturation is:
where ni is the number of atoms with valence vi.
That is, an atom that has a valence of x contributes a total of x − 2 to the degree of unsaturation. The result is then halved and increased by 1.
Simplified formulae
For certain classes of molecules, the general formula can be simplified or rewritten more clearly. For example:
where
a = number of carbon atoms in the compound
b = number of hydrogen atoms in the compound
c = number of nitrogen atoms in the compound
f = number of halogen atoms in the compound
or
where C = number of carbons, H = number of hydrogens, X = number of halogens and N = number of nitrogens, gives an equivalent result.
In either case, oxygen and other divalent atoms do not contribute to the degree of unsaturation, as 2 − 2 = 0.
Explanation
For hydrocarbons, the DBE (or IHD) tells us the number of rings and/or extra bonds in a non-saturated structure, which equals the number of hydrogen pairs that are required to make the structure saturated, simply because joining two elements to form a ring or adding one extra bond (e.g., a single bond changed to a double bond) in a structure reduces the need for two H's. For non-hydrocarbons, the elements in a pair can include any elements in the lithium family and the fluorine family in the periodic table, not necessarily all H's.
A popular form of the formula is as follows:
where , , and represent the number of carbon, nitrogen, hydrogen and halogen atoms, respectively. Each of the terms on the RHS can be explained, respectively, as follows:
Except for the terminal carbons, every carbon chained to the structure with two single bonds requires a pair of hydrogen atoms attached to it. The number of carbons in the formula actually represents the number of hydrogen pairs required for that number of carbons to form a saturated structure. (This is also true if a carbon is added to the structure, whether it is inserted into a backbone chain, attached to a terminal to replace a hydrogen, or branched out from a carbon to replace a hydrogen.)
Each of the two terminal carbons in the backbone chain needs one extra hydrogen – that is why "1" is added to the formula. (A branch's terminal doesn't need an H added in the calculation because the H replaced by the branch can be counted as the H added to the branch terminal. This is also true for a branch terminated with any element.)
Except the terminal nitrogens, each nitrogen in the chain only requires one H attached to it, which is half a pair of hydrogens—that is why is in the formula, which gives a value of 1 for every two nitrogens. (This is also true if nitrogen is added into the structure, whether it is inserted into a backbone chain, attached to a terminal to replace an H, or branched out from a C to replace an H.)
The represents the number of hydrogen pairs because it gives a value of 1 for every two hydrogen atoms. It is subtracted in the formula to count how many pairs of hydrogen atoms are missing in the unsaturated structure, which tells us the degree of hydrogen deficiency. (No hydrogen pair is missing if , which corresponds to no hydrogen deficiency.)
The presence of is for a reason similar to .
Adding an oxygen atom to the structure requires no hydrogen added, which is why the number of oxygen atoms does not appear in the formula.
Furthermore, the formula can be generalised to include all elements of Group I (the hydrogen and lithium family), Group IV (the carbon family), Group V (the nitrogen family) and Group VII (the fluorine family) of CAS A group in the periodic table as follows:
Or simply,
See also
Iodine number - practical measure of number of double bonds in a sample
References
External links
Molecular weight and degree of unsaturation calculator
Degree of Unsaturation
Organic chemistry
Edible oil chemistry | Degree of unsaturation | Chemistry | 1,021 |
46,487,381 | https://en.wikipedia.org/wiki/Penicillium%20lassenii | Penicillium lassenii is an anamorph species of the genus of Penicillium.
References
Further reading
lassenii
Fungi described in 1971
Fungus species | Penicillium lassenii | Biology | 37 |
9,768,981 | https://en.wikipedia.org/wiki/Robert%20Koch%20Medal%20and%20Award | The Robert Koch Medal and Award are two prizes awarded annually by the German for excellence in the biomedical sciences. These awards grew out of early attempts by German physician Robert Koch to generate funding to support his research into the cause and cure for tuberculosis. Koch discovered the bacteria (Mycobacterium tuberculosis) responsible for the dreaded disease and rapidly acquired international support, including 500,000 gold marks from the Scottish-American philanthropist Andrew Carnegie.
The Robert Koch Prize
Since 1970, the Robert Koch Foundation has awarded prizes for major advances in the biomedical sciences, particularly in the fields of microbiology and immunology. The prestige of this award has grown over the past decades so that it is now widely regarded as the leading international scientific prize in microbiology. As has been described by a jury member for the prize, the committee often asks, "What would Robert Koch work on today?” to decide on research that should be granted recognition.
The more specific Robert Koch Prize is commonly considered one of the stepping-stones (along with other prizes such as the Lasker Award) to eventual Nobel Prize recognition for scientists in the fields of microbiology and immunology, and a number of Robert Koch Prize winners subsequently became Nobel laureates, such as César Milstein, Susumu Tonegawa and Harald zur Hausen. Other notable awardees include Albert Sabin, Jonas Salk and John Enders for their pioneering work on the development of polio vaccines. Only Enders was recognized with a Nobel Prize, together with Thomas Huckle Weller and Frederick Chapman Robbins.
Two separate Robert Koch Awards are presented annually: The Gold Robert Koch Gold Medal for accumulated excellence in biomedical research and the Robert Koch Prize, worth €120,000, for a major discovery in biomedical science.
Robert Koch Prize Winners since 1960
Source:
1960 (Germany), René Dubos (USA), (Japan), (Germany), (Germany), (Switzerland)
1962 John Franklin Enders (USA), Albert Sabin (USA), Jonas Salk (USA)
1963 Tomizo Yoshida (Japan)
1965 Gertrud Meißner
1966
1968 , ,
1970 (United Kingdom), (Finland), (Denmark)
1971 Gertrude Henle and Werner Henle (USA)
1972 (Netherlands), Alain de Weck (Switzerland)
1973 Jean Lindenmann (Switzerland), (Germany)
1974 (Germany)
1975 Harald zur Hausen (Germany), Heinz-G. Wittmann (Germany)
1976 (USA), Mark Richmond (United Kingdom)
1977 Jean Dausset (France), Jon J. van Rood (Netherlands)
1978 (Germany), (Germany)
1979 Ruth Arnon (Israel), Peter Starlinger (Germany)
1980 César Milstein (Argentina), Lewis W. Wannamaker (USA)
1981 Robert M. Chanock (USA), (Sweden)
1982 Raymond L. Erikson (USA), Franz Oesch (Germany)
1983 (Germany), Robert A. Weinberg (USA)
1984 (Germany), (USA)
1985 Stefania Jabłońska (Poland), Gérard Orth (France)
1986 Susumu Tonegawa (Japan)
1987 Mario Rizzetto (Italy), (Germany), John Skehel (United Kingdom)
1988 Donald Metcalf (Australia)
1989 Irun R. Cohen (Israel), Alex J. van der Eb (Netherlands)
1990 Lloyd J. Old (USA)
1991 Walter Fiers (Belgium), Tadatsugu Taniguchi (Japan)
1992 Kary B. Mullis (USA)
1993 Hans-Georg Rammensee (Germany), Daniel W. Bradley (USA), Michael Houghton (USA)
1994 (Germany), Manuel Elkin Patarroyo Murillo (Colombia)
1995 Shigekazu Nagata (Japan), Peter H. Krammer (Germany)
1996 (Switzerland), Klaus Rajewsky (Germany)
1997 Philippe Sansonetti (France)
1998 Yuan Chang (USA), Patrick S. Moore (USA)
1999 Ralph M. Steinman (USA)
2000 Stanley Falkow (USA)
2001 Axel Ullrich (Germany)
2002 Rudolf Jaenisch (USA)
2003 (Switzerland)
2004 Shizuo Akira (Japan), Bruce A. Beutler (USA), Jules A. Hoffmann (France)
2005 Brian J. Druker (USA)
2006 Peter Palese (USA), Yoshihiro Kawaoka (Japan)
2007 Pascale Cossart (France)
2008 Hans Robert Schöler (Germany), Irving Weissman (USA), Shinya Yamanaka (Japan)
2009 Carl F. Nathan (USA)
2010 Max Dale Cooper (USA)
2011 Jorge E. Galán (Argentina)
2012 Tasuku Honjo (Japan)
2013 Jeffrey I. Gordon (USA)
2014 (France), Alain Fischer (France)
2015 Ralf Bartenschlager (Germany), Charles M. Rice (USA)
2016 Alberto Mantovani (Italy), Michel C. Nussenzweig (USA)
2017 Rafi Ahmed (India / USA), Antonio Lanzavecchia (Italy / Switzerland)
2018 Jeffrey V. Ravetch (USA)
2019 Rino Rappuoli (Italy)
2020 Shimon Sakaguchi (Japan)
2021 Yasmine Belkaid (Algeria / USA), Andreas J. Bäumler (Germany / USA)
2022 Philip Felgner (USA), Drew Weissman (USA)
2023 Timothy A. Springer (USA), Francisco Sánchez Madrid (Spain)
2024 Lalita Ramakrishnan (USA / UK)
Robert Koch Gold Medal winners since 1974
1974 (Sweden)
1977 Pierre Grabar (France)
1978 Theodor von Brand (Germany), Saul Krugman (USA)
1979 Sir Christopher Andrewes (United Kingdom)
1980 Emmy Klieneberger-Nobel (United Kingdom)
1981 Maclyn McCarty (USA)
1982 (France), Walter Pagel (United Kingdom), Karel Styblo (Netherlands)
1985 Richard M. Krause (USA)
1986 Ernst Ruska (Germany)
1987 Hans J. Müller-Eberhard (USA)
1988 Willy Burgdorfer (USA)
1989 Maurice Hilleman (USA)
1990 Ernst L. Wynder (USA)
1991 (Germany)
1992 Piet Borst (Netherlands), (USA)
1993 Karl Lennert (Germany), (Switzerland)
1994 (Germany)
1995 Charles Weissmann (Switzerland)
1996 Sir Gustav Nossal (Australia)
1997 Satoshi Ōmura (Japan)
1998 George Klein (Sweden)
1999 Barry Bloom (USA)
2000 Marco Baggiolini (Switzerland)
2001 Avrion Mitchison (United Kingdom)
2002 Agnes Ullmann (France)
2003 Tadamitsu Kishimoto (Japan)
2004 (Germany)
2005 Emil R. Unanue (USA)
2006 (Germany)
2007 Brigitte A. Askonas (United Kingdom)
2008 Philip Leder (USA)
2009 (Germany, Würzburg)
2010 Fotis C. Kafatos (Greece)
2011 Ernst-Ludwig Winnacker (Germany)
2012 Eckard Wimmer (Germany/USA)
2013 Anthony Fauci (USA)
2014 (Germany)
2015 Peter Piot (Belgium)
2016 Kai Simons (Germany)
2017 Christopher T. Walsh (USA)
2018 Staffan Normark (Sweden)
2019 Martin J. Blaser (USA)
2020 Thomas F. Meyer (Germany, Berlin)
2021 Kyriacos Costa Nicolaou (USA)
2022 Jörg Hacker (Germany)
2023 Patrice Courvalin (France)
2024 Stuart Schreiber (USA)
See also
List of medicine awards
References
Further reading
Embo Reports
External links
Robert Koch Foundation
German science and technology awards
Medicine awards
Robert Koch | Robert Koch Medal and Award | Technology | 1,604 |
64,256,623 | https://en.wikipedia.org/wiki/BitFunnel | BitFunnel is the search engine indexing algorithm and a set of components used in the Bing search engine, which were made open source in 2016. BitFunnel uses bit-sliced signatures instead of an inverted index in an attempt to reduce operations cost.
History
Progress on the implementation of BitFunnel was made public in early 2016, with the expectation that there would be a usable implementation later that year. In September 2016, the source code was made available via GitHub. A paper discussing the BitFunnel algorithm and implementation was released as through the Special Interest Group on Information Retrieval of the Association for Computing Machinery in 2017 and won the Best Paper Award.
Components
BitFunnel consists of three major components:
BitFunnel – the text search/retrieval system itself
WorkBench – a tool for preparing text for use in BitFunnel
NativeJIT – a software component that takes expressions that use C data structures and transforms them into highly optimized assembly code
Algorithm
Initial problem and solution overview
The BitFunnel paper describes the "matching problem", which occurs when an algorithm must identify documents through the usage of keywords. The goal of the problem is to identify a set of matches given a corpus to search and a query of keyword terms to match against. This problem is commonly solved through inverted indexes, where each searchable item is maintained with a map of keywords.
In contrast, BitFunnel represents each searchable item through a signature. A signature is a sequence of bits which describe a Bloom filter of the searchable terms in a given searchable item. The bloom filter is constructed through hashing through several bit positions.
Theoretical implementation of bit-string signatures
The signature of a document (D) can be described as the logical-or of its term signatures:
Similarly, a query for a document (Q) can be defined as a union:
Additionally, a document D is a member of the set M''' when the following condition is satisfied:
This knowledge is then combined to produce a formula where M''' is identified by documents which match the query signature:
These steps and their proofs are discussed in the 2017 paper.
Pseudocode for bit-string signatures
This algorithm is described in the 2017 paper.
References
External links
BitFunnel · GitHub
BitFunnel · BitFunnel
Data management
Search algorithms
Database index techniques
Free and open-source software
Microsoft free software
Microsoft Research
Software using the MIT license
Free software programmed in C++ | BitFunnel | Technology | 510 |
35,189,754 | https://en.wikipedia.org/wiki/Serre%E2%80%93Tate%20theorem | In algebraic geometry, the Serre–Tate theorem says that an abelian scheme and its p-divisible group have the same infinitesimal deformation theory. This was first proved by Jean-Pierre Serre when the reduction of the abelian variety is ordinary, using the Greenberg functor; then John Tate gave a proof in the general case by a different method. Their proofs were not published, but they were summarized in the notes of the Lubin–Serre–Tate seminar (Woods Hole, 1964). Other proofs were published by Messing (1962) and Drinfeld (1976).
References
: see, vol.2, p. 854, comments on Tate's letter from Jan.10, 1964.
Abelian varieties
Theorems in algebraic geometry | Serre–Tate theorem | Mathematics | 160 |
20,422,283 | https://en.wikipedia.org/wiki/NGC%2015 | NGC 15 is a spiral galaxy located in the Pegasus constellation. It was discovered by Albert Marth on October 30, 1864.
References
External links
Galaxies discovered in 1864
Spiral galaxies
Pegasus (constellation)
0015
00082
000661
18641030 | NGC 15 | Astronomy | 51 |
2,318,333 | https://en.wikipedia.org/wiki/RRKM%20theory | The Rice–Ramsperger–Kassel–Marcus (RRKM) theory is a theory of chemical reactivity. It was developed by Rice and Ramsperger in 1927 and Kassel in 1928 (RRK theory) and generalized (into the RRKM theory) in 1952 by Marcus who took the transition state theory developed by Eyring in 1935 into account. These methods enable the computation of simple estimates of the unimolecular reaction rates from a few characteristics of the potential energy surface.
Assumption
Assume that the molecule consists of harmonic oscillators, which are connected and can exchange energy with each other.
Assume the possible excitation energy of the molecule to be , which enables the reaction to occur.
The rate of intra-molecular energy distribution is much faster than that of reaction itself.
As a corollary to the above, the potential energy surface does not have any "bottlenecks" for which certain vibrational modes may be trapped for longer than the average time of the reaction
Derivation
Assume that is an excited molecule:
where stands for product, and for the critical atomic configuration with the maximum energy along the reaction coordinate.
The unimolecular rate constant is obtained as follows:
where is the microcanonical transition state theory rate constant, is the sum of states for the active degrees of freedom in the transition state, is the quantum number of angular momentum, is the collision frequency between molecule and bath molecules, and are the molecular vibrational and external rotational partition functions.
See also
Transition state theory
References
External links
An RRKM online calculator
Chemical physics
Quantum chemistry
Molecular physics
Chemical kinetics | RRKM theory | Physics,Chemistry | 323 |
25,497,425 | https://en.wikipedia.org/wiki/Solar%20eclipse%20of%20December%2016%2C%202085 | An annular solar eclipse will occur at the Moon's ascending node of orbit between Sunday, December 16 and Monday, December 17, 2085, with a magnitude of 0.9971. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres wide. Occurring about 3.7 days before perigee (on December 20, 2085, at 14:40 UTC), the Moon's apparent diameter will be larger.
The path of annularity will be visible from parts of Micronesia and southwestern Mexico. A partial solar eclipse will also be visible for parts of northern Australia, Oceania, Hawaii, and western North America.
Eclipse details
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.
Eclipse season
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.
Related eclipses
Eclipses in 2085
A penumbral lunar eclipse on January 10.
A penumbral lunar eclipse on June 8.
An annular solar eclipse on June 22.
A penumbral lunar eclipse on July 7.
A penumbral lunar eclipse on December 1.
An annular solar eclipse on December 16.
Metonic
Preceded by: Solar eclipse of February 27, 2082
Followed by: Solar eclipse of October 4, 2089
Tzolkinex
Preceded by: Solar eclipse of November 4, 2078
Followed by: Solar eclipse of January 27, 2093
Half-Saros
Preceded by: Lunar eclipse of December 10, 2076
Followed by: Lunar eclipse of December 21, 2094
Tritos
Preceded by: Solar eclipse of January 16, 2075
Followed by: Solar eclipse of November 15, 2096
Solar Saros 143
Preceded by: Solar eclipse of December 6, 2067
Followed by: Solar eclipse of December 29, 2103
Inex
Preceded by: Solar eclipse of January 5, 2057
Followed by: Solar eclipse of November 27, 2114
Triad
Preceded by: Solar eclipse of February 16, 1999
Followed by: Solar eclipse of October 17, 2172
Solar eclipses of 2083–2087
Saros 143
Metonic series
Tritos series
Inex series
Notes
References
2085 12 16
2085 12 16
2085 12 16
2085 in science | Solar eclipse of December 16, 2085 | Astronomy | 634 |
26,186,533 | https://en.wikipedia.org/wiki/Bo%C3%B6tes%20II | Boötes II or Boo II is a dwarf spheroidal galaxy situated in the constellation Boötes and discovered in 2007 in the data obtained by Sloan Digital Sky Survey. The galaxy is located at the distance of about 42 kpc from the Sun and moves towards the Sun with the speed of 120 km/s. It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an approximately round shape with the half-light radius of about 51 pc.
Boötes II is one of the smallest and faintest satellites of the Milky Way—its integrated luminosity is about 1,000 times that of the Sun (absolute visible magnitude of about −2.7), which is much lower than the luminosity of the majority of globular clusters. However the mass of the galaxy is substantial corresponding to the mass to light ratio of more than 100.
The stellar population of Boötes II consists mainly of moderately old stars formed 10–12 billion years ago. The metallicity of these old stars is low at , which means that they contain 80 times less heavy elements than the Sun. Currently there is no star formation in Boötes II. The measurements have so far failed to detect any neutral hydrogen in it—the upper limit is only 86 solar masses.
Boötes II is located only 1.5 degrees (~1.6 kpc) away from another dwarf galaxy—Boötes I, although they are unlikely to be physically associated because they move in opposite directions relative to the Milky Way. Their relative velocity—about 200 km/s is too high. It is more likely associated with the Sagittarius Stream and, therefore, with the Sagittarius Dwarf Elliptical Galaxy (SagDEG). Boötes II may be either a satellite galaxy of SagDEG or one of its star clusters torn from the main galaxy 4–7 billion years ago.
Notes
References
Dwarf spheroidal galaxies
4713552
Boötes
Local Group
Milky Way Subgroup
Astronomical objects discovered in 2007 | Boötes II | Astronomy | 410 |
275,553 | https://en.wikipedia.org/wiki/Tammar%20wallaby | The tammar wallaby (Notamacropus eugenii), also known as the dama wallaby or darma wallaby, is a small macropod native to South and Western Australia. Though its geographical range has been severely reduced since European colonisation, the tammar wallaby remains common within its reduced range and is listed as "Least Concern" by the International Union for Conservation of Nature (IUCN). It has been introduced to New Zealand and reintroduced to some areas of Australia where it had been previously extirpated. Skull variations differentiate between tammar wallabies from Western Australia, Kangaroo Island, and mainland South Australia, making them distinct population groups.
The tammar wallaby is among the smallest of the wallabies in the genus Notamacropus. Its coat colour is largely grey. The tammar wallaby has several notable adaptations, including the ability to retain energy while hopping, colour vision, and the ability to drink seawater. A nocturnal species, it spends the nighttime in grassland habitat and the daytime in shrubland. It is also very gregarious and has a seasonal, promiscuous mating pattern. A female tammar wallaby can nurse a joey in her pouch while keeping an embryo in her uterus. The tammar wallaby is a model species for research on marsupials, and on mammals in general. Its genome was sequenced in 2011.
Taxonomy and classification
The tammar wallaby was seen in the Houtman Abrolhos off Western Australia by survivors of the 1628 Batavia shipwreck, and recorded by François Pelsaert in his 1629 Ongeluckige Voyagie. It was first described in 1817 by the French naturalist Anselme Gaëtan Desmarest, who gave it the name eugenii based on a specimen found on an island then known as Ile Eugene in the Nuyts Archipelago off South Australia, which is now known as St. Peter Island. The island's French name was given in honour of Eugene Hamelin, caption of the ship Naturaliste; whose name is now the specific name of the tammar wallaby. The common name of the animal is derived from the thickets of the shrub locally known as tamma (Allocasuarina campestris) that sheltered it in Western Australia. It is also known as the dama wallaby or darma wallaby.
The tammar wallaby is traditionally classified together with the kangaroos, wallaroos and several other species of wallaby in the genus Macropus, and in the subgenus Notamacropus with the other brush wallabies, all of which have a facial stripe. However, some authors have proposed elevating the three subgenera of Macropus, Macropus (sensu stricto), Osphranter, and Notamacropus into distinct genera, making the tammar's specific name Notamacropus eugenii. This has been supported by genetic studies.
Fossil evidence of the tammar wallaby exists from the Late Pleistocene Eraremains were found in the Naracoorte Caves. The mainland and island-dwelling tammar wallabies split from each other 7,000–15,000 years ago, while the South Australian and Western Australian animals diverged around 50,000 years ago. The extirpated tammar wallabies on Flinders Island were greyer in colour with thinner skulls than present-day Kangaroo Island tammars, which are in turn larger than the East and West Wallabi Islands animals. The island tammar wallabies were once thought to be a separate species from the mainland population.
A 1991 examination of tammar wallaby skulls from different parts of the species' range found that the populations can be divided into three distinct groups: one group consisting of the populations from mainland Western Australia, East and West Wallabi Islands, Garden Island and Middle Island; a second group consisting of the populations from Flinders Island, 19th-century mainland Southern Australia and New Zealand; and a third group consisting of the population from Kangaroo Island. The Western Australia Department of Environment and Conservation listed these populations as the subspecies Macropus eugenii derbianus, M. e. eugenii and M. e. decres, respectively.
A 2017 study found many genetic differences between tammars from Western and South Australia and comparably little between the Kangaroo island and introduced New Zealand tammars. The researchers proposed dividing the species into two subspecies; the subspecific name eugenii for South Australian tammars and derbianus for those from Western Australia.
Characteristics and adaptations
One of the smallest wallaby species, the tammar wallaby features a proportionally small head with large ears, and an elongated tail, with a thick base. It has dark greyish upperparts with a paler underside and rufous-coloured sides and limbs. The tammar wallaby exhibits great sexual dimorphism, males reaching in weight compared to for females. Males are long while females are , while both sexes stand tall. The tail has a length of for males and for females.
Locomotion
As with most macropods, the tammar wallaby moves around by hopping. This species typically leaps with 3.5 landings per second. Proximal muscles at the knee and hip joints provide the power for each leap, which shifts to the ankle muscles as the animal pushes off. As it lands, the energy of the jump is converted into strain energy made when its leg tendons are stretched. As it leaps back off the ground, the tammar wallaby can recover much of this energy for reuse through elastic recoil. When on the move, animal's respiration is tried to its hopping cycle, inhaling when leaping and exhaling when landing. As it moves faster, its heart rate increases nearly twice as much as its hopping frequency.
The amount of energy stored in the tendons increases with the animal's speed and the weight of the load it is carrying. This is particularly helpful for mothers carrying young, and explains why tammar wallabies can increase their hopping speed without using more energy. The tammar wallaby shares this characteristic with other macropods that move on flat terrain, like the red kangaroo. By comparison, rock-wallabies, such as the yellow-footed rock-wallaby, have traded efficient energy-saving for greater tendon strength: an adaption for rocky cliffs which allows them to leap higher and lowers the risk of their tendons breaking.
Senses
The tammar wallaby can see at 324° peripheral vision and 50° binocular vision, which gives them a wide field view but still being about to see their hands in front of them. It can discern light gradients better than most other small mammals, such as rabbits. Its vision is, nevertheless, not as good as that of a cat or human. Tammar wallabies appear to have some colour vision: its eyes have only blue sensitive and green sensitive photoreceptor cones, allowing it to see colour in the blue-green band of the colour spectrum, but not the longer wavelengths of the red-yellow band. Nevertheless, in the band where it can see colour, it can differentiate between two monochromatic colours with wavelengths as close as apart.
The pinna (ear) of the tammar wallaby is mobile, allowing it to track sounds from different parts of its surroundings without moving its head. A tammar wallaby can point its pinna at a sound source and increase its eardrum's sound pressure by 25–30 dB at 5kHz. When the pinna moves away from the sound source, the animal's hearing level quickly drops. When born, a tammar wallaby's sense of smell is already developed; this allows the newborn to find its mother's pouch by scent.
Thermoregulation and water balance
Tammar wallabies lick their forearms and pant to keep cool in hot weather. They breathe more heavily and lose more water when the temperature is over . Tammar wallabies cannot survive in temperatures above and must find cooler surroundings. To prevent dehydration, tammar wallabies urinate less and suck up water from the distal colon, which gives them relatively dry feces. Being able to concentrate more urine in their kidneys allows them to survive on seawater.
Ecology and life history
During the day, tammar wallabies stay close to scrub for shade and move out to more open grassland by nightfall.In winter their home ranges are about , but in the dry summers they range further afield to search for quality food, needing about of space. Tammar wallaby home ranges overlap with those of conspecifics. Like all macropods, the tammar wallaby is herbivorous. They are known to both graze and browse, but the latter is less effective, as they commonly drop leaves when chewing on them. When eating large leaves, tammar wallabies handle them with their fingers. Tammar wallabies consume several plant species such as heart-leaved poison (Gastrolobium bilobum), small-flowered wallaby grass (Austrodanthonia setacea), and marri (Corymbia calophylla). They survive on several islands that have no fresh water, subsisting on seawater.
Tammar wallabies gather into groups which lessens the chance of an individual being taken by a predator. As the group increases in size, tammar wallabies spend more time feeding, grooming, and interacting and less time being vigilant and moving around. They are also more likely to rest on their sides rather than in a more alert posture where their head is held up. Predators of the tammar wallaby include dingoes, feral cats, red foxes and wedge-tailed eagles. They may also have been preyed upon by the extinct thylacine. Tammar wallabies appear to respond more to the sight than the sound of predators. They can also use their acute sense of smell to detect a potential threat. When a predator is detected, a tammar wallaby will alert others by thumping its foot. When lost, young tammar wallabies are known to emit a distress call and adult females may respond with a similar call.
Breeding and development
The tammar wallaby has a promiscuous mating system. It is a seasonal breeder and with many births taking place between late January and early February. During the breeding season, the male's prostate and bulbourethral gland enlarge while the weight of the testes remain the same. Around two weeks prior to the first births, the males start checking the reproductive status of the females by sniffing their urogenital openings and pouches. After giving birth, females enter estrus and allow males to mate with them. However, a male that attempts to mate with an estrous female may risk attacks from other males. A male can achieve reproductive success by mate-guarding. During the estrous period, males establish a dominance hierarchy, and the higher ranking males will try to prevent subordinates from mating with estrous females. Several males may pursue a single female.
The female tammar wallaby is receptive shortly after giving birth. Tammar wallabies undergo embryonic diapause and the blastocyst remains dormant for nearly a year. A joey in the pouch prevents the blastocyst from developing for the first six months and experiments have shown that removing the joey within this time period will stimulate the blastocyst's development. However, after this, the blastocyst remains dormant even after the joey has left. It begins to develop by the summer solstice at the end of December. A 2019 study found that more males are born due to a greater amount of Y chromosome sperm in sires. To balance out the sex ratios, tammar mothers are more likely to abandon male joeys and more females survive to weaning periods.
The lactation period of the tammar is divided into phases 2A, 2B, and 3 (pregnancy is labeled phase 1). Phase 2A encompasses the first 100–120 days after birth, and the underdeveloped young is fed diluted milk which is richer in carbohydrates than proteins and lipids. This allows for the rapid growth of important organs and internal systems including the respiratory system, lymphoid system, and nervous system. During this phase, the young remains latched on to a teat. Phase 2B lasts for another 100 days; the young suckles intermittently but still does not leave the pouch. The composition of the milk is similar, though the proteins are different. During phase 3, the joey can leave the pouch and eat plant material. The joey will continue to suckle, the teat having enlarged and the milk having become richer in proteins and lipids over carbohydrates to give the joey more energy. During this time, the joey also experiences rapid development and transitions from ectothermy to endothermy. The joey no longer needs the pouch by 250 days and is fully weaned at 300–350 days. The tammar wallaby has been observed to engage in alloparental care, in which an adult may adopt another's young. Female tammar wallabies may mature at nine months and live to age fourteen, while males mature around two years and live for eleven years.
Health
In one population of tammar wallabies, the tick species Ixodes hirsti was found to infest them during autumn and winter while those of the genus Amblyomma were more common in spring and summer. In late 1998 and again in early 1999, 120–230 tammar died suddenly in research facilities and zoos in New South Wales and Queensland, perishing less than 12 hours after their sickness was discovered, with most showing no symptoms prior. Necropsies revealed haemorrhaging of the muscles, and numerous internal organs. The syndrome is known as tammar sudden death syndrome and the pathogen is an orbivirus of the family Reoviridae. It does not occur south of Sydney, and treatment is difficult due to the rapid progression of the disease.
Population dynamics and conservation
The tammar wallaby is listed as Least Concern by the IUCN as of 2016, being particularly numerous on Kangaroo Island and four Western Australian islands. It has a maximum population of 50,000 mature individuals in total. However, the fragmentation of its range has led to high amounts of inbreeding and physical deformities in some populations.
Since European colonisation, tammar wallabies on both mainland Australia and some of the islands have greatly declined or even been eradicated. In the early 20th century, the mainland population in Western Australia was described as numerous throughout the southwest, but declining in agricultural areas to the north. Clearings made for wheat and sheep caused the population to fall even further. Starting in the 19th century, tammar wallabies in the Eyre Peninsula and around Adelaide were decimated by mobs of hunters protecting agriculture. As a result, they were extirpated from both these areas in the 20th century. Tammars from Flinders Island and St Peter Island were eradicated in a similar manner.
Tammar wallabies from these areas were introduced to Kawau Island in New Zealand by Sir George Grey in 1870. They were introduced to the Rotorua area in the early 20th century. Since then, they have flourished to the point where their foraging has damaged local plants. Pest control operators have used sodium fluoroacetate to control their populations, a practice which has been controversial because of its possible effect on organisms not targeted by the poison, including humans. Cyanide pellets have been used as an alternative.
In 1985, tammar wallabies were introduced to the North Island of the Houtman Abrolhos and have made similar impacts on native vegetation. Their numbers grew to over 450 individuals, but by 2008 culling efforts appeared to have reduced their numbers to 25 individuals. In 2003, the Monarto Zoo temporarily kept 85 tammar wallabies from New Zealand awaiting reintroduction to the Innes National Park on the Yorke Peninsula in South Australia. Four releases have been made, and the population increased to 100–120 animals by 2012. Tammar wallaby were reintroduced to Kalbarri National Park in 2010 though the project was not considered successful as the majority of radio-collared individuals did not last more than a year.
Resistance to sodium fluoroacetate
Different tammar wallaby populations have varying levels of resistance to sodium fluoroacetate. Mainland Western Australian tammar wallabies appear to be the most resistant, while those on Kangaroo Island are much more vulnerable. Tammar wallabies from New Zealand are also vulnerable, as poison has been successfully used to control their populations. Tammar wallabies from East and West Wallabi Islands and Garden Island, which do not have plants containing sodium fluoroacetate, are less resistant than mainland Western Australian tammar wallabies, but are more resistant than those from Kangaroo Island. This suggests that tammar wallabies originated in South Australia and developed a resistance to sodium fluoroacetate when they reached Western Australia, where the poison is found in plants.
Use in science
The tammar wallaby is a model organism for studying marsupial biology, as well as mammal biology in general. It has been used in the fields of reproductive biology, immunology, metabolism, neurobiology and many others. Its "seasonal and lactational control of its reproduction" makes its reproduction particularly suited for study. Saunders and colleagues (2017) have suggested the bipedal tammar as a better model for research into human spinal cord injuries than quadrupedal rodents. Tammar wallabies are easy to keep in captivity as they are non-aggressive, can adjust to surgeries and reproduce easily, requiring just one male for five females. Tammar wallabies used for scientific study are generally housed in outdoor pens with enough water and shelter, instead of a laboratory.
The genomes of marsupials are of great interest to scientists studying comparative genomics, and the study of tammar wallabies has provided much information about the genetics of marsupials and mammals in general. Marsupials are at a convenient degree of evolutionary divergence from humans; mice are too close and have not developed many different functions, while birds are genetically too remote. Key immune genes from the tammar wallaby were highlighted and studied in 2009.
In 2011, the tammar would become the second marsupial to have its full genome sequenced after the grey short-tailed opossum. The researchers found "innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation". The researchers also found new HOX genes that control gene expression, as well as new microRNAs. Genes for producing milk were shown to be novel while gonad genes appeared to be more conserved. Prior to the full genome sequencing of marsupials, the identification and characterization of important immunological components were limited in most marsupial species. The current sequencing and annotation of whole marsupial genomes have been useful for the further understanding of marsupial immune systems by simplifying the characterization of immune molecules in marsupials, and has aided in biomedical research. A 2017 molecular study of the tammar and the mink found the potential involvement of EGF, FOXO, CDKN1A in controlling mammalian embryonic diapause. IL-10 and IL-10Δ3 are conserved in the tammar showing their immune system can respond to pathogens similarly to other eutherian mammals using these same immune components.
A compound in the milk of the tammar wallaby called AGG01 has the potential to be a new and effective antibiotic. AGG01 is a protein, and in laboratory tests has proven to be far more powerful than penicillin. It kills many types pathogenic bacteria (both Gram-positive and Gram-negative) and at least one fungus. Subsequent analysis of the genome has led to the finding of several cathelicidin peptides, which could also be used as antibiotics. The foregut of the tammar wallaby contains species of bacteria belonging to the phyla Bacillota, Bacteroidota and Pseudomonadota. New species have been discovered: WG–1 of Pseudomonadota and TWA4 of Bacillota. These bacteria produce less methane than others and do not require CO2 to survive. This has important environmental implications, as this information could be used to reduce carbon production in livestock.
References
External links
Tammar wallaby resources Bioinformatics, Walter and Eliza Hall Institute of Medical Research
Tammar wallaby facts National Zoological Park
Mammals described in 1817
Macropods
Mammals of South Australia
Mammals of Western Australia
Marsupials of Australia
Animal models
Taxa named by Anselme Gaëtan Desmarest | Tammar wallaby | Biology | 4,290 |
47,516,955 | https://en.wikipedia.org/wiki/Filters%20in%20topology | Filters in topology, a subfield of mathematics, can be used to study topological spaces and define all basic topological notions such as convergence, continuity, compactness, and more. Filters, which are special families of subsets of some given set, also provide a common framework for defining various types of limits of functions such as limits from the left/right, to infinity, to a point or a set, and many others. Special types of filters called have many useful technical properties and they may often be used in place of arbitrary filters.
Filters have generalizations called (also known as ) and , all of which appear naturally and repeatedly throughout topology. Examples include neighborhood filters/bases/subbases and uniformities. Every filter is a prefilter and both are filter subbases. Every prefilter and filter subbase is contained in a unique smallest filter, which they are said to . This establishes a relationship between filters and prefilters that may often be exploited to allow one to use whichever of these two notions is more technically convenient. There is a certain preorder on families of sets (subordination), denoted by that helps to determine exactly when and how one notion (filter, prefilter, etc.) can or cannot be used in place of another. This preorder's importance is amplified by the fact that it also defines the notion of filter convergence, where by definition, a filter (or prefilter) to a point if and only if where is that point's neighborhood filter. Consequently, subordination also plays an important role in many concepts that are related to convergence, such as cluster points and limits of functions. In addition, the relation which denotes and is expressed by saying that also establishes a relationship in which is to as a subsequence is to a sequence (that is, the relation which is called , is for filters the analog of "is a subsequence of").
Filters were introduced by Henri Cartan in 1937 and subsequently used by Bourbaki in their book as an alternative to the similar notion of a net developed in 1922 by E. H. Moore and H. L. Smith.
Filters can also be used to characterize the notions of sequence and net convergence. But unlike sequence and net convergence, filter convergence is defined in terms of subsets of the topological space and so it provides a notion of convergence that is completely intrinsic to the topological space; indeed, the category of topological spaces can be equivalently defined entirely in terms of filters. Every net induces a canonical filter and dually, every filter induces a canonical net, where this induced net (resp. induced filter) converges to a point if and only if the same is true of the original filter (resp. net). This characterization also holds for many other definitions such as cluster points. These relationships make it possible to switch between filters and nets, and they often also allow one to choose whichever of these two notions (filter or net) is more convenient for the problem at hand.
However, assuming that "subnet" is defined using either of its most popular definitions (which are those given by Willard and by Kelley), then in general, this relationship does extend to subordinate filters and subnets because as detailed below, there exist subordinate filters whose filter/subordinate-filter relationship cannot be described in terms of the corresponding net/subnet relationship; this issue can however be resolved by using a less commonly encountered definition of "subnet", which is that of an AA-subnet.
Thus filters/prefilters and this single preorder provide a framework that seamlessly ties together fundamental topological concepts such as topological spaces (via neighborhood filters), neighborhood bases, convergence, various limits of functions, continuity, compactness, sequences (via sequential filters), the filter equivalent of "subsequence" (subordination), uniform spaces, and more; concepts that otherwise seem relatively disparate and whose relationships are less clear.
Motivation
Archetypical example of a filter
The archetypical example of a filter is the at a point in a topological space which is the family of sets consisting of all neighborhoods of
By definition, a neighborhood of some given point is any subset whose topological interior contains this point; that is, such that Importantly, neighborhoods are required to be open sets; those are called .
Listed below are those fundamental properties of neighborhood filters that ultimately became the definition of a "filter."
A is a set of subsets of that satisfies all of the following conditions:
: – just as since is always a neighborhood of (and of anything else that it contains);
: – just as no neighborhood of is empty;
: If – just as the intersection of any two neighborhoods of is again a neighborhood of ;
: If then – just as any subset of that includes a neighborhood of will necessarily a neighborhood of (this follows from and the definition of "a neighborhood of ").
Generalizing sequence convergence by using sets − determining sequence convergence without the sequence
A is by definition a map from the natural numbers into the space
The original notion of convergence in a topological space was that of a sequence converging to some given point in a space, such as a metric space.
With metrizable spaces (or more generally first-countable spaces or Fréchet–Urysohn spaces), sequences usually suffices to characterize, or "describe", most topological properties, such as the closures of subsets or continuity of functions.
But there are many spaces where sequences can be used to describe even basic topological properties like closure or continuity.
This failure of sequences was the motivation for defining notions such as nets and filters, which fail to characterize topological properties.
Nets directly generalize the notion of a sequence since nets are, by definition, maps from an arbitrary directed set into the space A sequence is just a net whose domain is with the natural ordering. Nets have their own notion of convergence, which is a direct generalization of sequence convergence.
Filters generalize sequence convergence in a different way by considering the values of a sequence.
To see how this is done, consider a sequence which is by definition just a function whose value at is denoted by rather than by the usual parentheses notation that is commonly used for arbitrary functions.
Knowing only the image (sometimes called "the range") of the sequence is not enough to characterize its convergence; multiple sets are needed.
It turns out that the needed sets are the following, which are called the of the sequence :
These sets completely determine this sequence's convergence (or non-convergence) because given any point, this sequence converges to it if and only if for every neighborhood (of this point), there is some integer such that contains all of the points This can be reworded as:
every neighborhood must contain some set of the form as a subset.
Or more briefly: every neighborhood must contain some tail as a subset.
It is this characterization that can be used with the above family of tails to determine convergence (or non-convergence) of the sequence
Specifically, with the family of in hand, the is no longer needed to determine convergence of this sequence (no matter what topology is placed on ).
By generalizing this observation, the notion of "convergence" can be extended from sequences/functions to families of sets.
The above set of tails of a sequence is in general not a filter but it does "" a filter via taking its (which consists of all supersets of all tails). The same is true of other important families of sets such as any neighborhood basis at a given point, which in general is also not a filter but does generate a filter via its upward closure (in particular, it generates the neighborhood filter at that point). The properties that these families share led to the notion of a , also called a , which by definition is any family having the minimal properties necessary and sufficient for it to generate a filter via taking its upward closure.
Nets versus filters − advantages and disadvantages
Filters and nets each have their own advantages and drawbacks and there's no reason to use one notion exclusively over the other.
Depending on what is being proved, a proof may be made significantly easier by using one of these notions instead of the other. Both filters and nets can be used to completely characterize any given topology.
Nets are direct generalizations of sequences and can often be used similarly to sequences, so the learning curve for nets is typically much less steep than that for filters.
However, filters, and especially ultrafilters, have many more uses outside of topology, such as in set theory, mathematical logic, model theory (ultraproducts, for example), abstract algebra, combinatorics, dynamics, order theory, generalized convergence spaces, Cauchy spaces, and in the definition and use of hyperreal numbers.
Like sequences, nets are and so they have the .
For example, like sequences, nets can be "plugged into" other functions, where "plugging in" is just function composition.
Theorems related to functions and function composition may then be applied to nets.
One example is the universal property of inverse limits, which is defined in terms of composition of functions rather than sets and it is more readily applied to functions like nets than to sets like filters (a prominent example of an inverse limit is the Cartesian product).
Filters may be awkward to use in certain situations, such as when switching between a filter on a space and a filter on a dense subspace
In contrast to nets, filters (and prefilters) are families of and so they have the .
For example, if is surjective then the under of an arbitrary filter or prefilter is both easily defined and guaranteed to be a prefilter on 's domain, whereas it is less clear how to pullback (unambiguously/without choice) an arbitrary sequence (or net) so as to obtain a sequence or net in the domain (unless is also injective and consequently a bijection, which is a stringent requirement). Similarly, the intersection of any collection of filters is once again a filter whereas it is not clear what this could mean for sequences or nets.
Because filters are composed of subsets of the very topological space that is under consideration, topological set operations (such as closure or interior) may be applied to the sets that constitute the filter.
Taking the closure of all the sets in a filter is sometimes useful in functional analysis for instance.
Theorems and results about images or preimages of sets under a function may also be applied to the sets that constitute a filter; an example of such a result might be one of continuity's characterizations in terms of preimages of open/closed sets or in terms of the interior/closure operators.
Special types of filters called have many useful properties that can significantly help in proving results.
One downside of nets is their dependence on the directed sets that constitute their domains, which in general may be entirely unrelated to the space In fact, the class of nets in a given set is too large to even be a set (it is a proper class); this is because nets in can have domains of cardinality.
In contrast, the collection of all filters (and of all prefilters) on is a set whose cardinality is no larger than that of
Similar to a topology on a filter on is "intrinsic to " in the sense that both structures consist of subsets of and neither definition requires any set that cannot be constructed from (such as or other directed sets, which sequences and nets require).
Preliminaries, notation, and basic notions
In this article, upper case Roman letters like and denote sets (but not families unless indicated otherwise) and will denote the power set of A subset of a power set is called (or simply, ) where it is if it is a subset of Families of sets will be denoted by upper case calligraphy letters such as , , and .
Whenever these assumptions are needed, then it should be assumed that is non-empty and that etc. are families of sets over
The terms "prefilter" and "filter base" are synonyms and will be used interchangeably.
Warning about competing definitions and notation
There are unfortunately several terms in the theory of filters that are defined differently by different authors.
These include some of the most important terms such as "filter."
While different definitions of the same term usually have significant overlap, due to the very technical nature of filters (and point–set topology), these differences in definitions nevertheless often have important consequences.
When reading mathematical literature, it is recommended that readers check how the terminology related to filters is defined by the author.
For this reason, this article will clearly state all definitions as they are used.
Unfortunately, not all notation related to filters is well established and some notation varies greatly across the literature (for example, the notation for the set of all prefilters on a set) so in such cases this article uses whatever notation is most self describing or easily remembered.
The theory of filters and prefilters is well developed and has a plethora of definitions and notations, many of which are now unceremoniously listed to prevent this article from becoming prolix and to allow for the easy look up of notation and definitions.
Their important properties are described later.
Sets operations
The or in of a family of sets is
and similarly the of is
Throughout, is a map.
Topology notation
Denote the set of all topologies on a set
Suppose is any subset, and is any point.
If then
Nets and their tails
A is a set together with a preorder, which will be denoted by (unless explicitly indicated otherwise), that makes into an () ; this means that for all there exists some such that For any indices the notation is defined to mean while is defined to mean that holds but it is true that (if is antisymmetric then this is equivalent to ).
A is a map from a non-empty directed set into
The notation will be used to denote a net with domain
Warning about using strict comparison
If is a net and then it is possible for the set which is called , to be empty (for example, this happens if is an upper bound of the directed set ).
In this case, the family would contain the empty set, which would prevent it from being a prefilter (defined later).
This is the (important) reason for defining as rather than or even and it is for this reason that in general, when dealing with the prefilter of tails of a net, the strict inequality may not be used interchangeably with the inequality
Filters and prefilters
The following is a list of properties that a family of sets may possess and they form the defining properties of filters, prefilters, and filter subbases. Whenever it is necessary, it should be assumed that
Many of the properties of defined above and below, such as "proper" and "directed downward," do not depend on so mentioning the set is optional when using such terms. Definitions involving being "upward closed in " such as that of "filter on " do depend on so the set should be mentioned if it is not clear from context.
There are no prefilters on (nor are there any nets valued in ), which is why this article, like most authors, will automatically assume without comment that whenever this assumption is needed.
Basic examples
Named examples
The singleton set is called the or It is the unique filter on because it is a subset of every filter on ; however, it need not be a subset of every prefilter on
The dual ideal is also called (despite not actually being a filter). It is the only dual ideal on that is not a filter on
If is a topological space and then the neighborhood filter at is a filter on By definition, a family is called a (resp. a ) at if and only if is a prefilter (resp. is a filter subbase) and the filter on that generates is equal to the neighborhood filter The subfamily of open neighborhoods is a filter base for Both prefilters also form a bases for topologies on with the topology generated being coarser than This example immediately generalizes from neighborhoods of points to neighborhoods of non-empty subsets
is an if for some sequence of points
is an or a on if is a filter on generated by some elementary prefilter. The filter of tails generated by a sequence that is not eventually constant is necessarily an ultrafilter. Every principal filter on a countable set is sequential as is every cofinite filter on a countably infinite set. The intersection of finitely many sequential filters is again sequential.
The set of all cofinite subsets of (meaning those sets whose complement in is finite) is proper if and only if is infinite (or equivalently, is infinite), in which case is a filter on known as the or the on If is finite then is equal to the dual ideal which is not a filter. If is infinite then the family of complements of singleton sets is a filter subbase that generates the Fréchet filter on As with any family of sets over that contains the kernel of the Fréchet filter on is the empty set:
The intersection of all elements in any non-empty family is itself a filter on called the or of which is why it may be denoted by Said differently, Because every filter on has as a subset, this intersection is never empty. By definition, the infimum is the finest/largest (relative to ) filter contained as a subset of each member of
If are filters then their infimum in is the filter If are prefilters then is a prefilter that is coarser than both (that is, ); indeed, it is one of the finest such prefilters, meaning that if is a prefilter such that then necessarily More generally, if are non−empty families and if then and is a greatest element of
Let and let
The or of denoted by is the smallest (relative to ) dual ideal on containing every element of as a subset; that is, it is the smallest (relative to ) dual ideal on containing as a subset.
This dual ideal is where is the -system generated by
As with any non-empty family of sets, is contained in filter on if and only if it is a filter subbase, or equivalently, if and only if is a filter on in which case this family is the smallest (relative to ) filter on containing every element of as a subset and necessarily
Let and let
The or of denoted by if it exists, is by definition the smallest (relative to ) filter on containing every element of as a subset.
If it exists then necessarily (as defined above) and will also be equal to the intersection of all filters on containing
This supremum of exists if and only if the dual ideal is a filter on
The least upper bound of a family of filters may fail to be a filter. Indeed, if contains at least two distinct elements then there exist filters for which there does exist a filter that contains both
If is not a filter subbase then the supremum of does not exist and the same is true of its supremum in but their supremum in the set of all dual ideals on will exist (it being the degenerate filter ).
If are prefilters (resp. filters on ) then is a prefilter (resp. a filter) if and only if it is non-degenerate (or said differently, if and only if mesh), in which case it is coarsest prefilters (resp. coarsest filter) on that is finer (with respect to ) than both this means that if is any prefilter (resp. any filter) such that then necessarily in which case it is denoted by
Other examples
Let and let which makes a prefilter and a filter subbase that is not closed under finite intersections. Because is a prefilter, the smallest prefilter containing is The -system generated by is In particular, the smallest prefilter containing the filter subbase is equal to the set of all finite intersections of sets in The filter on generated by is All three of the -system generates, and are examples of fixed, principal, ultra prefilters that are principal at the point is also an ultrafilter on
Let be a topological space, and define where is necessarily finer than If is non-empty (resp. non-degenerate, a filter subbase, a prefilter, closed under finite unions) then the same is true of If is a filter on then is a prefilter but not necessarily a filter on although is a filter on equivalent to
The set of all dense open subsets of a (non-empty) topological space is a proper -system and so also a prefilter. If the space is a Baire space, then the set of all countable intersections of dense open subsets is a -system and a prefilter that is finer than If (with ) then the set of all such that has finite Lebesgue measure is a proper -system and a free prefilter that is also a proper subset of The prefilters and are equivalent and so generate the same filter on
Since is a Baire space, every countable intersection of sets in is dense in (and also comeagre and non-meager) so the set of all countable intersections of elements of is a prefilter and -system; it is also finer than, and not equivalent to,
Ultrafilters
There are many other characterizations of "ultrafilter" and "ultra prefilter," which are listed in the article on ultrafilters. Important properties of ultrafilters are also described in that article.
The ultrafilter lemma
The following important theorem is due to Alfred Tarski (1930).
A consequence of the ultrafilter lemma is that every filter is equal to the intersection of all ultrafilters containing it.
Assuming the axioms of Zermelo–Fraenkel (ZF), the ultrafilter lemma follows from the Axiom of choice (in particular from Zorn's lemma) but is strictly weaker than it. The ultrafilter lemma implies the Axiom of choice for finite sets. If dealing with Hausdorff spaces, then most basic results (as encountered in introductory courses) in Topology (such as Tychonoff's theorem for compact Hausdorff spaces and the Alexander subbase theorem) and in functional analysis (such as the Hahn–Banach theorem) can be proven using only the ultrafilter lemma; the full strength of the axiom of choice might not be needed.
Kernels
The kernel is useful in classifying properties of prefilters and other families of sets.
If then and this set is also equal to the kernel of the -system that is generated by
In particular, if is a filter subbase then the kernels of all of the following sets are equal:
(1) (2) the -system generated by and (3) the filter generated by
If is a map then
Equivalent families have equal kernels.
Two principal families are equivalent if and only if their kernels are equal.
Classifying families by their kernels
If is a principal filter on then and
and is also the smallest prefilter that generates
Family of examples: For any non-empty the family is free but it is a filter subbase if and only if no finite union of the form covers in which case the filter that it generates will also be free. In particular, is a filter subbase if is countable (for example, the primes), a meager set in a set of finite measure, or a bounded subset of If is a singleton set then is a subbase for the Fréchet filter on
Characterizing fixed ultra prefilters
If a family of sets is fixed (that is, ) then is ultra if and only if some element of is a singleton set, in which case will necessarily be a prefilter. Every principal prefilter is fixed, so a principal prefilter is ultra if and only if is a singleton set.
Every filter on that is principal at a single point is an ultrafilter, and if in addition is finite, then there are no ultrafilters on other than these.
The next theorem shows that every ultrafilter falls into one of two categories: either it is free or else it is a principal filter generated by a single point.
Finer/coarser, subordination, and meshing
The preorder that is defined below is of fundamental importance for the use of prefilters (and filters) in topology. For instance, this preorder is used to define the prefilter equivalent of "subsequence", where "" can be interpreted as " is a subsequence of " (so "subordinate to" is the prefilter equivalent of "subsequence of"). It is also used to define prefilter convergence in a topological space.
The definition of meshes with which is closely related to the preorder is used in topology to define cluster points.
Two families of sets and are , indicated by writing if If do not mesh then they are . If then are said to if mesh, or equivalently, if the of which is the family
does not contain the empty set, where the trace is also called the of
Example: If is a subsequence of then is subordinate to in symbols: and also
Stated in plain English, the prefilter of tails of a subsequence is always subordinate to that of the original sequence.
To see this, let be arbitrary (or equivalently, let be arbitrary) and it remains to show that this set contains some
For the set to contain it is sufficient to have
Since are strictly increasing integers, there exists such that and so holds, as desired.
Consequently,
The left hand side will be a subset of the right hand side if (for instance) every point of is unique (that is, when is injective) and is the even-indexed subsequence because under these conditions, every tail (for every ) of the subsequence will belong to the right hand side filter but not to the left hand side filter.
For another example, if is any family then always holds and furthermore,
A non-empty family that is coarser than a filter subbase must itself be a filter subbase.
Every filter subbase is coarser than both the -system that it generates and the filter that it generates.
If are families such that the family is ultra, and then is necessarily ultra. It follows that any family that is equivalent to an ultra family will necessarily ultra. In particular, if is a prefilter then either both and the filter it generates are ultra or neither one is ultra.
The relation is reflexive and transitive, which makes it into a preorder on
The relation is antisymmetric but if has more than one point then it is symmetric.
Equivalent families of sets
The preorder induces its canonical equivalence relation on where for all is to if any of the following equivalent conditions hold:
The upward closures of are equal.
Two upward closed (in ) subsets of are equivalent if and only if they are equal.
If then necessarily and is equivalent to
Every equivalence class other than contains a unique representative (that is, element of the equivalence class) that is upward closed in
Properties preserved between equivalent families
Let be arbitrary and let be any family of sets. If are equivalent (which implies that ) then for each of the statements/properties listed below, either it is true of or else it is false of :
Not empty
Proper (that is, is not an element)
Moreover, any two degenerate families are necessarily equivalent.
Filter subbase
Prefilter
In which case generate the same filter on (that is, their upward closures in are equal).
Free
Principal
Ultra
Is equal to the trivial filter
In words, this means that the only subset of that is equivalent to the trivial filter the trivial filter. In general, this conclusion of equality does not extend to non−trivial filters (one exception is when both families are filters).
Meshes with
Is finer than
Is coarser than
Is equivalent to
Missing from the above list is the word "filter" because this property is preserved by equivalence.
However, if are filters on then they are equivalent if and only if they are equal; this characterization does extend to prefilters.
Equivalence of prefilters and filter subbases
If is a prefilter on then the following families are always equivalent to each other:
;
the -system generated by ;
the filter on generated by ;
and moreover, these three families all generate the same filter on (that is, the upward closures in of these families are equal).
In particular, every prefilter is equivalent to the filter that it generates.
By transitivity, two prefilters are equivalent if and only if they generate the same filter.
Every prefilter is equivalent to exactly one filter on which is the filter that it generates (that is, the prefilter's upward closure).
Said differently, every equivalence class of prefilters contains exactly one representative that is a filter.
In this way, filters can be considered as just being distinguished elements of these equivalence classes of prefilters.
A filter subbase that is also a prefilter can be equivalent to the prefilter (or filter) that it generates.
In contrast, every prefilter is equivalent to the filter that it generates.
This is why prefilters can, by and large, be used interchangeably with the filters that they generate while filter subbases cannot.
Set theoretic properties and constructions relevant to topology
Trace and meshing
If is a prefilter (resp. filter) on then the trace of which is the family is a prefilter (resp. a filter) if and only if mesh (that is, ), in which case the trace of is said to be .
The trace is always finer than the original family; that is,
If is ultra and if mesh then the trace is ultra.
If is an ultrafilter on then the trace of is a filter on if and only if
For example, suppose that is a filter on is such that Then mesh and generates a filter on that is strictly finer than
When prefilters mesh
Given non-empty families the family
satisfies and
If is proper (resp. a prefilter, a filter subbase) then this is also true of both
In order to make any meaningful deductions about from needs to be proper (that is, which is the motivation for the definition of "mesh".
In this case, is a prefilter (resp. filter subbase) if and only if this is true of both
Said differently, if are prefilters then they mesh if and only if is a prefilter.
Generalizing gives a well known characterization of "mesh" entirely in terms of subordination (that is, ):
Two prefilters (resp. filter subbases) mesh if and only if there exists a prefilter (resp. filter subbase) such that and
If the least upper bound of two filters exists in then this least upper bound is equal to
Images and preimages under functions
Throughout, will be maps between non-empty sets.
Images of prefilters
Let Many of the properties that may have are preserved under images of maps; notable exceptions include being upward closed, being closed under finite intersections, and being a filter, which are not necessarily preserved.
Explicitly, if one of the following properties is true of then it will necessarily also be true of (although possibly not on the codomain unless is surjective):
ultra, ultrafilter, filter, prefilter, filter subbase, dual ideal, upward closed, proper/non-degenerate, ideal, closed under finite unions, downward closed, directed upward.
Moreover, if is a prefilter then so are both
The image under a map of an ultra set is again ultra and if is an ultra prefilter then so is
If is a filter then is a filter on the range but it is a filter on the codomain if and only if is surjective.
Otherwise it is just a prefilter on and its upward closure must be taken in to obtain a filter.
The upward closure of is
where if is upward closed in (that is, a filter) then this simplifies to:
If then taking to be the inclusion map shows that any prefilter (resp. ultra prefilter, filter subbase) on is also a prefilter (resp. ultra prefilter, filter subbase) on
Preimages of prefilters
Let
Under the assumption that is surjective:
is a prefilter (resp. filter subbase, -system, closed under finite unions, proper) if and only if this is true of
However, if is an ultrafilter on then even if is surjective (which would make a prefilter), it is nevertheless still possible for the prefilter to be neither ultra nor a filter on
If is not surjective then denote the trace of by where in this case particular case the trace satisfies:
and consequently also:
This last equality and the fact that the trace is a family of sets over means that to draw conclusions about the trace can be used in place of and the can be used in place of
For example:
is a prefilter (resp. filter subbase, -system, proper) if and only if this is true of
In this way, the case where is not (necessarily) surjective can be reduced down to the case of a surjective function (which is a case that was described at the start of this subsection).
Even if is an ultrafilter on if is not surjective then it is nevertheless possible that which would make degenerate as well. The next characterization shows that degeneracy is the only obstacle. If is a prefilter then the following are equivalent:
is a prefilter;
is a prefilter;
;
meshes with
and moreover, if is a prefilter then so is
If and if denotes the inclusion map then the trace of is equal to This observation allows the results in this subsection to be applied to investigating the trace on a set.
Subordination is preserved by images and preimages
The relation is preserved under both images and preimages of families of sets.
This means that for families
Moreover, the following relations always hold for family of sets :
where equality will hold if is surjective.
Furthermore,
If then
and where equality will hold if is injective.
Products of prefilters
Suppose is a family of one or more non-empty sets, whose product will be denoted by and for every index let
denote the canonical projection.
Let be non−empty families, also indexed by such that for each
The of the families is defined identically to how the basic open subsets of the product topology are defined (had all of these been topologies). That is, both the notations
denote the family of all cylinder subsets such that for all but finitely many and where for any one of these finitely many exceptions (that is, for any such that necessarily ).
When every is a filter subbase then the family is a filter subbase for the filter on generated by
If is a filter subbase then the filter on that it generates is called the .
If every is a prefilter on then will be a prefilter on and moreover, this prefilter is equal to the coarsest prefilter such that
for every
However, may fail to be a filter on even if every is a filter on
Convergence, limits, and cluster points
Throughout, is a topological space.
Prefilters vs. filters
With respect to maps and subsets, the property of being a prefilter is in general more well behaved and better preserved than the property of being a filter. For instance, the image of a prefilter under some map is again a prefilter; but the image of a filter under a non-surjective map is a filter on the codomain, although it will be a prefilter. The situation is the same with preimages under non-injective maps (even if the map is surjective). If is a proper subset then any filter on will not be a filter on although it will be a prefilter.
One advantage that filters have is that they are distinguished representatives of their equivalence class (relative to ), meaning that any equivalence class of prefilters contains a unique filter. This property may be useful when dealing with equivalence classes of prefilters (for instance, they are useful in the construction of completions of uniform spaces via Cauchy filters). The many properties that characterize ultrafilters are also often useful. They are used to, for example, construct the Stone–Čech compactification. The use of ultrafilters generally requires that the ultrafilter lemma be assumed. But in the many fields where the axiom of choice (or the Hahn–Banach theorem) is assumed, the ultrafilter lemma necessarily holds and does not require an addition assumption.
A note on intuition
Suppose that is a non-principal filter on an infinite set has one "upward" property (that of being closed upward) and one "downward" property (that of being directed downward).
Starting with any there always exists some that is a subset of ; this may be continued ad infinitum to get a sequence of sets in with each being a subset of The same is true going "upward", for if then there is no set in that contains as a proper subset.
Thus when it comes to limiting behavior (which is a topic central to the field of topology), going "upward" leads to a dead end, while going "downward" is typically fruitful. So to gain understanding and intuition about how filters (and prefilter) relate to concepts in topology, the "downward" property is usually the one to concentrate on. This is also why so many topological properties can be described by using only prefilters, rather than requiring filters (which only differ from prefilters in that they are also upward closed).
The "upward" property of filters is less important for topological intuition but it is sometimes useful to have for technical reasons. For example, with respect to every filter subbase is contained in a unique smallest filter but there may not exist a unique smallest prefilter containing it.
Limits and convergence
A family is said to to a point of if Explicitly, means that every neighborhood contains some as a subset (that is, ); thus the following then holds: In words, a family converges to a point or subset if and only if it is than the neighborhood filter at
A family converging to a point may be indicated by writing and saying that is a of if this limit is a point (and not a subset), then is also called a .
As usual, is defined to mean that and is the limit point of that is, if also (If the notation "" did not also require that the limit point be unique then the equals sign would no longer be guaranteed to be transitive).
The set of all limit points of is denoted by
In the above definitions, it suffices to check that is finer than some (or equivalently, finer than every) neighborhood base in of the point (for example, such as or when ).
Examples
If is Euclidean space and denotes the Euclidean norm (which is the distance from the origin, defined as usual), then all of the following families converge to the origin:
the prefilter of all open balls centered at the origin, where
the prefilter of all closed balls centered at the origin, where This prefilter is equivalent to the one above.
the prefilter where is a union of spheres centered at the origin having progressively smaller radii. This family consists of the sets as ranges over the positive integers.
any of the families above but with the radius ranging over (or over any other positive decreasing sequence) instead of over all positive reals.
Drawing or imagining any one of these sequences of sets when has dimension suggests that intuitively, these sets "should" converge to the origin (and indeed they do). This is the intuition that the above definition of a "convergent prefilter" make rigorous.
Although was assumed to be the Euclidean norm, the example above remains valid for any other norm on
The one and only limit point in of the free prefilter is since every open ball around the origin contains some open interval of this form.
The fixed prefilter does not converges in to any and so although does converge to the since
However, not every fixed prefilter converges to its kernel. For instance, the fixed prefilter also has kernel but does not converges (in ) to it.
The free prefilter of intervals does not converge (in ) to any point.
The same is also true of the prefilter because it is equivalent to and equivalent families have the same limits.
In fact, if is any prefilter in any topological space then for every
More generally, because the only neighborhood of is itself (that is, ), every non-empty family (including every filter subbase) converges to
For any point its neighborhood filter always converges to More generally, any neighborhood basis at converges to
A point is always a limit point of the principle ultra prefilter and of the ultrafilter that it generates.
The empty family does not converge to any point.
Basic properties
If converges to a point then the same is true of any family finer than
This has many important consequences.
One consequence is that the limit points of a family are the same as the limit points of its upward closure:
In particular, the limit points of a prefilter are the same as the limit points of the filter that it generates.
Another consequence is that if a family converges to a point then the same is true of the family's trace/restriction to any given subset of
If is a prefilter and then converges to a point of if and only if this is true of the trace
If a filter subbase converges to a point then do the filter and the -system that it generates, although the converse is not guaranteed. For example, the filter subbase does not converge to in although the (principle ultra) filter that it generates does.
Given the following are equivalent for a prefilter
converges to
converges to
There exists a family equivalent to that converges to
Because subordination is transitive, if and moreover, for every both and the maximal/ultrafilter converge to Thus every topological space induces a canonical convergence defined by
At the other extreme, the neighborhood filter is the smallest (that is, coarsest) filter on that converges to that is, any filter converging to must contain as a subset. Said differently, the family of filters that converge to consists exactly of those filter on that contain as a subset.
Consequently, the finer the topology on then the prefilters exist that have any limit points in
Cluster points
A family is said to a point of if it meshes with the neighborhood filter of that is, if Explicitly, this means that and every neighborhood of
In particular, a point is a or an of a family if meshes with the neighborhood filter at The set of all cluster points of is denoted by where the subscript may be dropped if not needed.
In the above definitions, it suffices to check that meshes with some (or equivalently, meshes with every) neighborhood base in of
When is a prefilter then the definition of " mesh" can be characterized entirely in terms of the subordination preorder
Two equivalent families of sets have the exact same limit points and also the same cluster points. No matter the topology, for every both and the principal ultrafilter cluster at
If clusters to a point then the same is true of any family coarser than Consequently, the cluster points of a family are the same as the cluster points of its upward closure:
In particular, the cluster points of a prefilter are the same as the cluster points of the filter that it generates.
Given the following are equivalent for a prefilter :
clusters at
The family generated by clusters at
There exists a family equivalent to that clusters at
for every neighborhood of
If is a filter on then for every neighborhood
There exists a prefilter subordinate to (that is, ) that converges to
This is the filter equivalent of " is a cluster point of a sequence if and only if there exists a subsequence converging to
In particular, if is a cluster point of a prefilter then is a prefilter subordinate to that converges to
The set of all cluster points of a prefilter satisfies
Consequently, the set of all cluster points of prefilter is a closed subset of This also justifies the notation for the set of cluster points.
In particular, if is non-empty (so that is a prefilter) then since both sides are equal to
Properties and relationships
Just like sequences and nets, it is possible for a prefilter on a topological space of infinite cardinality to not have cluster points or limit points.
If is a limit point of then is necessarily a limit point of any family than (that is, if then ).
In contrast, if is a cluster point of then is necessarily a cluster point of any family than (that is, if mesh and then mesh).
Equivalent families and subordination
Any two equivalent families can be used in the definitions of "limit of" and "cluster at" because their equivalency guarantees that if and only if and also that if and only if
In essence, the preorder is incapable of distinguishing between equivalent families.
Given two prefilters, whether or not they mesh can be characterized entirely in terms of subordination.
Thus the two most fundamental concepts related to (pre)filters to Topology (that is, limit and cluster points) can both be defined in terms of the subordination relation. This is why the preorder is of such great importance in applying (pre)filters to Topology.
Limit and cluster point relationships and sufficient conditions
Every limit point of a non-degenerate family is also a cluster point; in symbols:
This is because if is a limit point of then mesh, which makes a cluster point of But in general, a cluster point need not be a limit point. For instance, every point in any given non-empty subset is a cluster point of the principle prefilter (no matter what topology is on ) but if is Hausdorff and has more than one point then this prefilter has no limit points; the same is true of the filter that this prefilter generates.
However, every cluster point of an prefilter is a limit point. Consequently, the limit points of an prefilter are the same as its cluster points: that is to say, a given point is a cluster point of an ultra prefilter if and only if converges to that point.
Although a cluster point of a filter need not be a limit point, there will always exist a finer filter that does converge to it; in particular, if clusters at then is a filter subbase whose generated filter converges to
If is a filter subbase such that then In particular, any limit point of a filter subbase subordinate to is necessarily also a cluster point of
If is a cluster point of a prefilter then is a prefilter subordinate to that converges to
If and if is a prefilter on then every cluster point of belongs to and any point in is a limit point of a filter on
Primitive sets
A subset is called if it is the set of limit points of some ultrafilter (or equivalently, some ultra prefilter). That is, if there exists an ultrafilter such that is equal to which recall denotes the set of limit points of Since limit points are the same as cluster points for ultra prefilters, a subset is primitive if and only if it is equal to the set of cluster points of some ultra prefilter
For example, every closed singleton subset is primitive. The image of a primitive subset of under a continuous map is contained in a primitive subset of
Assume that are two primitive subset of
If is an open subset of that intersects then for any ultrafilter such that
In addition, if are distinct then there exists some and some ultrafilters such that and
Other results
If is a complete lattice then:
The limit inferior of is the infimum of the set of all cluster points of
The limit superior of is the supremum of the set of all cluster points of
is a convergent prefilter if and only if its limit inferior and limit superior agree; in this case, the value on which they agree is the limit of the prefilter.
Limits of functions defined as limits of prefilters
Suppose is a map from a set into a topological space and If is a limit point (respectively, a cluster point) of then is called a or (respectively, a )
Explicitly, is a limit of with respect to if and only if which can be written as (by definition of this notation) and stated as If the limit is unique then the arrow may be replaced with an equals sign The neighborhood filter can be replaced with any family equivalent to it and the same is true of
The definition of a convergent net is a special case of the above definition of a limit of a function.
Specifically, if is a net then
where the left hand side states that is a limit while the right hand side states that is a limit with respect to (as just defined above).
The table below shows how various types of limits encountered in analysis and topology can be defined in terms of the convergence of images (under ) of particular prefilters on the domain
This shows that prefilters provide a general framework into which many of the various definitions of limits fit.
The limits in the left-most column are defined in their usual way with their obvious definitions.
Throughout, let be a map between topological spaces,
If is Hausdorff then all arrows in the table may be replaced with equal signs and may be replaced with
By defining different prefilters, many other notions of limits can be defined; for example,
Divergence to infinity
Divergence of a real-valued function to infinity can be defined/characterized by using the prefilters
where along if and only if and similarly, along if and only if The family can be replaced by any family equivalent to it, such as for instance (in real analysis, this would correspond to replacing the strict inequality in the definition with and the same is true of and
So for example, if then if and only if holds. Similarly, if and only if or equivalently, if and only if
More generally, if is valued in (or some other seminormed vector space) and if then if and only if holds, where
Filters and nets
This section will describe the relationships between prefilters and nets in great detail because of how important these details are applying filters to topology − particularly in switching from utilizing nets to utilizing filters and vice verse.
Nets to prefilters
In the definitions below, the first statement is the standard definition of a limit point of a net (respectively, a cluster point of a net) and it is gradually reworded until the corresponding filter concept is reached.
If is a map and is a net in then
Prefilters to nets
A is a pair consisting of a non-empty set and an element
For any family let
Define a canonical preorder on pointed sets by declaring
There is a canonical map defined by
If then the tail of the assignment starting at is
Although is not, in general, a partially ordered set, it is a directed set if (and only if) is a prefilter.
So the most immediate choice for the definition of "the net in induced by a prefilter " is the assignment from into
If is a prefilter on is a net in and the prefilter associated with is ; that is:
This would not necessarily be true had been defined on a proper subset of
If is a net in then it is in general true that is equal to because, for example, the domain of may be of a completely different cardinality than that of (since unlike the domain of the domain of an arbitrary net in could have cardinality).
Partially ordered net
The domain of the canonical net is in general not partially ordered. However, in 1955 Bruns and Schmidt discovered a construction (detailed here: Filter (set theory)#Partially ordered net) that allows for the canonical net to have a domain that is both partially ordered and directed; this was independently rediscovered by Albert Wilansky in 1970.
Because the tails of this partially ordered net are identical to the tails of (since both are equal to the prefilter ), there is typically nothing lost by assuming that the domain of the net associated with a prefilter is both directed partially ordered. If can further be assumed that the partially ordered domain is also a dense order.
Subordinate filters and subnets
The notion of " is subordinate to " (written ) is for filters and prefilters what " is a subsequence of " is for sequences.
For example, if denotes the set of tails of and if denotes the set of tails of the subsequence (where ) then (which by definition means ) is true but is in general false.
If is a net in a topological space and if is the neighborhood filter at a point then
If is an surjective open map, and is a prefilter on that converges to then there exist a prefilter on such that and is equivalent to (that is, ).
Subordination analogs of results involving subsequences
The following results are the prefilter analogs of statements involving subsequences. The condition "" which is also written is the analog of " is a subsequence of " So "finer than" and "subordinate to" is the prefilter analog of "subsequence of." Some people prefer saying "subordinate to" instead of "finer than" because it is more reminiscent of "subsequence of."
Non-equivalence of subnets and subordinate filters
Subnets in the sense of Willard and subnets in the sense of Kelley are the most commonly used definitions of "subnet."
The first definition of a subnet ("Kelley-subnet") was introduced by John L. Kelley in 1955.
Stephen Willard introduced in 1970 his own variant ("Willard-subnet") of Kelley's definition of subnet.
AA-subnets were introduced independently by Smiley (1957), Aarnes and Andenaes (1972), and Murdeshwar (1983); AA-subnets were studied in great detail by Aarnes and Andenaes but they are not often used.
A subset of a preordered space is or in if for every there exists some such that If contains a tail of then is said to be in }}; explicitly, this means that there exists some such that (that is, for all satisfying ). A subset is eventual if and only if its complement is not frequent (which is termed ).
A map between two preordered sets is if whenever satisfy then
Kelley did not require the map to be order preserving while the definition of an AA-subnet does away entirely with any map between the two nets' domains and instead focuses entirely on − the nets' common codomain.
Every Willard-subnet is a Kelley-subnet and both are AA-subnets.
In particular, if is a Willard-subnet or a Kelley-subnet of then
Example: If and is a constant sequence and if and then is an AA-subnet of but it is neither a Willard-subnet nor a Kelley-subnet of
AA-subnets have a defining characterization that immediately shows that they are fully interchangeable with sub(ordinate)filters.
Explicitly, what is meant is that the following statement is true for AA-subnets:
If are prefilters then if and only if is an AA-subnet of
If "AA-subnet" is replaced by "Willard-subnet" or "Kelley-subnet" then the above statement becomes . In particular, as this counter-example demonstrates, the problem is that the following statement is in general false:
statement: If are prefilters such that is a Kelley-subnet of
Since every Willard-subnet is a Kelley-subnet, this statement thus remains false if the word "Kelley-subnet" is replaced with "Willard-subnet".
If "subnet" is defined to mean Willard-subnet or Kelley-subnet then nets and filters are not completely interchangeable because there exists a filter–sub(ordinate)filter relationships that cannot be expressed in terms of a net–subnet relationship between the two induced nets. In particular, the problem is that Kelley-subnets and Willard-subnets are fully interchangeable with subordinate filters. If the notion of "subnet" is not used or if "subnet" is defined to mean AA-subnet, then this ceases to be a problem and so it becomes correct to say that nets and filters are interchangeable. Despite the fact that AA-subnets do not have the problem that Willard and Kelley subnets have, they are not widely used or known about.
Topologies and prefilters
Throughout, is a topological space.
Examples of relationships between filters and topologies
Bases and prefilters
Let be a family of sets that covers and define for every The definition of a base for some topology can be immediately reworded as: is a base for some topology on if and only if is a filter base for every
If is a topology on and then the definitions of is a basis (resp. subbase) for can be reworded as:
is a base (resp. subbase) for if and only if for every is a filter base (resp. filter subbase) that generates the neighborhood filter of at
Neighborhood filters
The archetypical example of a filter is the set of all neighborhoods of a point in a topological space.
Any neighborhood basis of a point in (or of a subset of) a topological space is a prefilter. In fact, the definition of a neighborhood base can be equivalently restated as: "a neighborhood base is any prefilter that is equivalent the neighborhood filter."
Neighborhood bases at points are examples of prefilters that are fixed but may or may not be principal.
If has its usual topology and if then any neighborhood filter base of is fixed by (in fact, it is even true that ) but is principal since
In contrast, a topological space has the discrete topology if and only if the neighborhood filter of every point is a principal filter generated by exactly one point.
This shows that a non-principal filter on an infinite set is not necessarily free.
The neighborhood filter of every point in topological space is fixed since its kernel contains (and possibly other points if, for instance, is not a T1 space). This is also true of any neighborhood basis at
For any point in a T1 space (for example, a Hausdorff space), the kernel of the neighborhood filter of is equal to the singleton set
However, it is possible for a neighborhood filter at a point to be principal but discrete (that is, not principal at a point).
A neighborhood basis of a point in a topological space is principal if and only if the kernel of is an open set. If in addition the space is T1 then so that this basis is principal if and only if is an open set.
Generating topologies from filters and prefilters
Suppose is not empty (and ). If is a filter on then is a topology on but the converse is in general false. This shows that in a sense, filters are topologies. Topologies of the form where is an filter on are an even more specialized subclass of such topologies; they have the property that proper subset is open or closed, but (unlike the discrete topology) never both. These spaces are, in particular, examples of door spaces.
If is a prefilter (resp. filter subbase, -system, proper) on then the same is true of both and the set of all possible unions of one or more elements of If is closed under finite intersections then the set is a topology on with both being bases for it. If the -system covers then both are also bases for If is a topology on then is a prefilter (or equivalently, a -system) if and only if it has the finite intersection property (that is, it is a filter subbase), in which case a subset will be a basis for if and only if is equivalent to in which case will be a prefilter.
Topological properties and prefilters
Neighborhoods and topologies
The neighborhood filter of a nonempty subset in a topological space is equal to the intersection of all neighborhood filters of all points in
A subset is open in if and only if whenever is a filter on and then
Suppose are topologies on
Then is finer than (that is, ) if and only if whenever is a filter on if then Consequently, if and only if for every filter and every if and only if
However, it is possible that while also for every filter converges to point of if and only if converges to point of
Closure
If is a prefilter on a subset then every cluster point of belongs to
If is a non-empty subset, then the following are equivalent:
is a limit point of a prefilter on Explicitly: there exists a prefilter such that
is a limit point of a filter on
There exists a prefilter such that
The prefilter meshes with the neighborhood filter Said differently, is a cluster point of the prefilter
The prefilter meshes with some (or equivalently, with every) filter base for (that is, with every neighborhood basis at ).
The following are equivalent:
is a limit points of
There exists a prefilter such that
Closed sets
If is not empty then the following are equivalent:
is a closed subset of
If is a prefilter on such that then
If is a prefilter on such that is an accumulation points of then
If is such that the neighborhood filter meshes with then
Hausdorffness
The following are equivalent:
is a Hausdorff space.
Every prefilter on converges to at most one point in
The above statement but with the word "prefilter" replaced by any one of the following: filter, ultra prefilter, ultrafilter.
Compactness
As discussed in this article, the Ultrafilter Lemma is closely related to many important theorems involving compactness.
The following are equivalent:
is a compact space.
Every ultrafilter on converges to at least one point in
That this condition implies compactness can be proven by using only the ultrafilter lemma. That compactness implies this condition can be proven without the ultrafilter lemma (or even the axiom of choice).
The above statement but with the word "ultrafilter" replaced by "ultra prefilter".
For every filter there exists a filter such that and converges to some point of
The above statement but with each instance of the word "filter" replaced by: prefilter.
Every filter on has at least one cluster point in
That this condition is equivalent to compactness can be proven by using only the ultrafilter lemma.
The above statement but with the word "filter" replaced by "prefilter".
Alexander subbase theorem: There exists a subbase such that every cover of by sets in has a finite subcover.
That this condition is equivalent to compactness can be proven by using only the ultrafilter lemma.
If is the set of all complements of compact subsets of a given topological space then is a filter on if and only if is compact.
Continuity
Let be a map between topological spaces
Given the following are equivalent:
is continuous at
Definition: For every neighborhood of there exists some neighborhood of such that
If is a filter on such that then
The above statement but with the word "filter" replaced by "prefilter".
The following are equivalent:
is continuous.
If is a prefilter on such that then
If is a limit point of a prefilter then is a limit point of
Any one of the above two statements but with the word "prefilter" replaced by "filter".
If is a prefilter on is a cluster point of is continuous, then is a cluster point in of the prefilter
A subset of a topological space is dense in if and only if for every the trace of the neighborhood filter along does not contain the empty set (in which case it will be a filter on ).
Suppose is a continuous map into a Hausdorff regular space and that is a dense subset of a topological space Then has a continuous extension if and only if for every the prefilter converges to some point in Furthermore, this continuous extension will be unique whenever it exists.
Products
Suppose is a non-empty family of non-empty topological spaces and that is a family of prefilters where each is a prefilter on
Then the product of these prefilters (defined above) is a prefilter on the product space which as usual, is endowed with the product topology.
If then if and only if
Suppose are topological spaces, is a prefilter on having as a cluster point, and is a prefilter on having as a cluster point.
Then is a cluster point of in the product space
However, if then there exist sequences such that both of these sequences have a cluster point in but the sequence does have a cluster point in
Example application: The ultrafilter lemma along with the axioms of ZF imply Tychonoff's theorem for compact Hausdorff spaces:
Let be compact topological spaces.
Assume that the ultrafilter lemma holds (because of the Hausdorff assumption, this proof does need the full strength of the axiom of choice; the ultrafilter lemma suffices).
Let be given the product topology (which makes a Hausdorff space) and for every let denote this product's projections.
If then is compact and the proof is complete so assume
Despite the fact that because the axiom of choice is not assumed, the projection maps are not guaranteed to be surjective.
Let be an ultrafilter on and for every let denote the ultrafilter on generated by the ultra prefilter
Because is compact and Hausdorff, the ultrafilter converges to a unique limit point (because of 's uniqueness, this definition does not require the axiom of choice).
Let where satisfies for every
The characterization of convergence in the product topology that was given above implies that
Thus every ultrafilter on converges to some point of which implies that is compact (recall that this implication's proof only required the ultrafilter lemma).
Examples of applications of prefilters
Uniformities and Cauchy prefilters
A uniform space is a set equipped with a filter on that has certain properties. A or is a prefilter on whose upward closure is a uniform space.
A prefilter on a uniform space with uniformity is called a if for every entourage there exists some that is , which means that
A is a minimal element (with respect to or equivalently, to ) of the set of all Cauchy filters on
Examples of minimal Cauchy filters include the neighborhood filter of any point
Every convergent filter on a uniform space is Cauchy. Moreover, every cluster point of a Cauchy filter is a limit point.
A uniform space is called (resp. ) if every Cauchy prefilter (resp. every elementary Cauchy prefilter) on converges to at least one point of (replacing all instance of the word "prefilter" with "filter" results in equivalent statement).
Every compact uniform space is complete because any Cauchy filter has a cluster point (by compactness), which is necessarily also a limit point (since the filter is Cauchy).
Uniform spaces were the result of attempts to generalize notions such as "uniform continuity" and "uniform convergence" that are present in metric spaces. Every topological vector space, and more generally, every topological group can be made into a uniform space in a canonical way. Every uniformity also generates a canonical induced topology. Filters and prefilters play an important role in the theory of uniform spaces. For example, the completion of a Hausdorff uniform space (even if it is not metrizable) is typically constructed by using minimal Cauchy filters.
Nets are less ideal for this construction because their domains are extremely varied (for example, the class of all Cauchy nets is not a set); sequences cannot be used in the general case because the topology might not be metrizable, first-countable, or even sequential.
The set of all on a Hausdorff topological vector space (TVS) can made into a vector space and topologized in such a way that it becomes a completion of (with the assignment becoming a linear topological embedding that identifies as a dense vector subspace of this completion).
More generally, a is a pair consisting of a set together a family of (proper) filters, whose members are declared to be "", having all of the following properties:
For each the discrete ultrafilter at is an element of
If is a subset of a proper filter then
If and if each member of intersects each member of then
The set of all Cauchy filters on a uniform space forms a Cauchy space. Every Cauchy space is also a convergence space.
A map between two Cauchy spaces is called if the image of every Cauchy filter in is a Cauchy filter in
Unlike the category of topological spaces, the category of Cauchy spaces and Cauchy continuous maps is Cartesian closed, and contains the category of proximity spaces.
Topologizing the set of prefilters
Starting with nothing more than a set it is possible to topologize the set
of all filter bases on with the , which is named after Marshall Harvey Stone.
To reduce confusion, this article will adhere to the following notational conventions:
Lower case letters for elements
Upper case letters for subsets
Upper case calligraphy letters for subsets (or equivalently, for elements such as prefilters).
Upper case double-struck letters for subsets
For every let
where These sets will be the basic open subsets of the Stone topology.
If then
From this inclusion, it is possible to deduce all of the subset inclusions displayed below with the exception of
For all
where in particular, the equality shows that the family is a -system that forms a basis for a topology on called the . It is henceforth assumed that carries this topology and that any subset of carries the induced subspace topology.
In contrast to most other general constructions of topologies (for example, the product, quotient, subspace topologies, etc.), this topology on was defined with using anything other than the set there were preexisting structures or assumptions on so this topology is completely independent of everything other than (and its subsets).
The following criteria can be used for checking for points of closure and neighborhoods.
If then:
: belongs to the closure of if and only if
: is a neighborhood of if and only if there exists some such that (that is, such that for all ).
It will be henceforth assumed that because otherwise and the topology is which is uninteresting.
Subspace of ultrafilters
The set of ultrafilters on (with the subspace topology) is a Stone space, meaning that it is compact, Hausdorff, and totally disconnected.
If has the discrete topology then the map defined by sending to the principal ultrafilter at is a topological embedding whose image is a dense subset of (see the article Stone–Čech compactification for more details).
Relationships between topologies on and the Stone topology on
Every induces a canonical map defined by which sends to the neighborhood filter of
If then if and only if
Thus every topology can be identified with the canonical map which allows to be canonically identified as a subset of (as a side note, it is now possible to place on and thus also on the topology of pointwise convergence on so that it now makes sense to talk about things such as sequences of topologies on converging pointwise).
For every the surjection is always continuous, closed, and open, but it is injective if and only if (that is, a Kolmogorov space).
In particular, for every topology the map is a topological embedding (said differently, every Kolmogorov space is a topological subspace of the space of prefilters).
In addition, if is a map such that (which is true of for instance), then for every the set is a neighborhood (in the subspace topology) of
See also
Notes
Proofs
Citations
References
(Provides an introductory review of filters in topology and in metric spaces.)
Filters
General topology | Filters in topology | Chemistry,Mathematics,Engineering | 15,179 |
13,769,508 | https://en.wikipedia.org/wiki/HD%20174179 | HD 174179 is a single star in the northern constellation of Lyra. It has a white hue and is dimly visible to the naked eye with an apparent visual magnitude of 6.06. The star is located at a distance of approximately 1,280 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −15 km/s.
The star is an estimated 33 million years old with a low projected rotational velocity of 5 km/s. It has 6.6 times the mass of the Sun and is radiating 2,036 times the Sun's luminosity from its photosphere at an effective temperature of 17,900 K.
HD 174179 is a Be star, showing Balmer emission lines in its spectrum at times. It has a stellar classification of B3IVp, with 'p' indicating spectral features of a shell star. A 1976 study found no emission features, but the star was reported to show emission lines again in later studies.
References
B-type subgiants
Shell stars
Lyra
Durchmusterung objects
174179
092243
7081 | HD 174179 | Astronomy | 232 |
28,325,198 | https://en.wikipedia.org/wiki/Consanguine%20marriage | Consanguine marriage is marriage between individuals who are closely related. Though it may involve incest, it implies more than the sexual nature of incest. In a clinical sense, marriage between two family members who are second cousins or closer qualifies as consanguineous marriage. This is based on the gene copies their offspring may receive. Though these unions are still prevalent in some communities, as seen across the Greater Middle East region, many other populations have seen a great decline in intra-family marriages.
Prevalence and stigma
Globally, 8.5% of children have consanguineous parents, and 20% of the human population live in communities practicing endogamy. Theories on the developments of consanguineous marriage as a taboo can be supported as being both a social and a biological development.
Social factors
From a social perspective, the observed inclination to practice consanguinity has been due to advantages to social and financial status. Upholding familial structure and assets, and ease of marital arrangements are valued among consanguineous marriages. Low age and a lack of awareness of the consequences of inbreeding are common in consanguineous marriages.
Consanguineous marriage is present in every religion, and cannot be accredited to any one religious mandate. Consanguinity is practiced regardless of religious influences and is a result of cultural, historical, regional, and socio-economic factors. A greater number of consanguineous marriages are observed in rural areas compared to urban areas within the same region. This is attributed to the tendency of individuals in rural areas to marry at younger ages, have a lower socio-economic status, and lesser education than those who live in urban areas. Parent's grade of job has also been credited as a factor.
In cases of incest involving a child and adult, legislation usually considers it to be a form of child sexual abuse.
Epidemiological features
Multiple studies have established consanguinity as a high cause for birth defects and abnormalities. A risk of autosomal recessive disorders increases in offspring coming from consanguineous marriages due to the increased likelihood of receiving recessive genes from cognate parents. According to population based case-control studies, a higher risk of stillbirth is associated with consanguineous marriages.
Inbreeding is associated with decreased cognitive abilities in children.
Younger ages of marriage are commonly seen in consanguineous marriages, which may account for the increase in fertility seen in these unions. Chances of postnatal mortality are higher in offspring. The first year holds the highest chance of death due to the risk of autosomal recessive genes. This is also the cause of health complications as children born from consanguinity enter adulthood.
See also
Avunculate marriage
Cousin marriage
Coefficient of relationship
Laws regarding incest
Sibling marriage
Xwedodah
References
Further reading
External links
Types of marriage
Genealogy
Incest
Medical genetics
Endogamy | Consanguine marriage | Biology | 604 |
11,128,761 | https://en.wikipedia.org/wiki/Xylaria%20mali | Xylaria mali is a plant pathogen that causes black rot on apple.
References
Fungal tree pathogens and diseases
Apple tree diseases
Xylariales
Fungi described in 1928
Fungus species | Xylaria mali | Biology | 37 |
21,512,236 | https://en.wikipedia.org/wiki/Space%20Foundation | The Space Foundation is an American nonprofit organization, the mission of which is to advocate for all sectors of the global space industry through space awareness activities, educational programs, and major industry events. It was founded in 1983.
Locations
Located in Colorado Springs, Colorado, the foundation's headquarters includes team offices, as well as conference and other facilities. Other offices are in Washington, D.C., Texas, and Florida.
Education
The Space Foundation delivers K-12 student programs in laboratory, classroom and after-school settings. Programs include STEM, social studies, history, the arts and literature and are available to individual classes, school districts, public and private school, colleges and universities offering education curriculum and homeschool organizations.
Space Symposium
The Space Foundation hosts the annual Space Symposium in Colorado Springs at the Broadmoor Hotel. The Space Symposium features presentations and panels that provide insight into space developments and the latest on critical industry issues. Each year, several awards are presented at the Space Symposium recognizing achievements in various space arenas.
The symposium includes an annual fundraiser called "Yuri's Night", named in honour of Russian cosmonaut Yuri Gagarin. In 2022, the foundation renamed the fundraiser as "A Celebration of Space: Discover What’s Next" due to the invasion of Ukraine by Russia.
Awards
General James E. Hill Lifetime Space Achievement Award
The General James E. Hill Lifetime Space Achievement Award is the highest honor bestowed by the Space Foundation, presented annually at a special luncheon held during the Space Symposium. The award recognizes outstanding individuals who have distinguished themselves through lifetime contributions to the welfare or betterment of humankind through the exploration, development and use of space, or the use of space technology, information, themes or resources in academic, cultural, industrial or other pursuits of broad benefit to humanity. Nominations are solicited throughout the global space industry and the honoree is selected by the Space Foundation's Board of Directors. Recipients of the General James E. Hill Lifetime Space Achievement Award include:
Alan Shepard Technology in Education Award
The Space Foundation, in conjunction with the Astronauts Memorial Foundation (AMF) and the National Aeronautics and Space Administration (NASA), annually presents the Alan Shepard Technology in Education Award to recognize outstanding contributions to creative and innovative use of technology in education by K-12 educators or district-level education personnel. Winners of the Alan Shepard Technology in Education Award include:
Douglas S. Morrow Public Outreach Award
The Space Foundation annually presents the Douglas S. Morrow Public Outreach Award in memory of Douglas S. Morrow, renowned Academy Award-winning writer and producer, space advocate and former Space Foundation Board Member, to an individual or organization who has made significant contributions to the public awareness and understanding of space programs. Winners of the Douglas S. Morrow Public Outreach Award include:
Space Achievement Award
The Space Foundation's Space Achievement Award recognizes individuals or organizations for space achievement, a breakthrough space technology or program or other achievements representing critical milestones in the evolution of space exploration and development. Winners of the Space Achievement Award include:
John L. Jack, Swigert Jr., Award for Space Exploration
The John L. "Jack" Swigert Jr., Award for Space Exploration recognizes extraordinary accomplishments by a company, space agency or consortium of organizations in the realm of space exploration and discovery. The award is in memory of astronaut John L. 'Jack' Swigert Jr., one of the inspirations for creating the Space Foundation. Winners of the John L. Jack Swigert Jr., Award for Space Exploration include:
Space Technology Hall of Fame
The Space Technology Hall of Fame was created in 1988 by the Space Foundation with cooperation from NASA and is administered by the Space Foundation. The foundation annually honors groups and individuals that, according to the organization, "transform technology originally developed for space exploration into products that help improve the quality of life here on Earth".
Since 1988, it has been inducting dozens of technologies and honoring hundreds of organizations and individuals that transform technology originally developed for space exploration into products that help improve the quality of life on Earth.
References
External links
Space Foundation - Home page
Organizations established in 1983
Non-profit organizations based in Colorado
Space organizations
Alan Shepard
Jack Swigert | Space Foundation | Astronomy | 842 |
39,750,328 | https://en.wikipedia.org/wiki/NGC%202082 | NGC 2082 is a barred spiral galaxy located approximately 60 million light-years away the constellation Dorado. It was discovered November 30, 1834 by John Herschel. The galaxy was originally considered to be part of the Dorado Group of galaxies, but was later removed from the list. NGC 2082 is now considered a member of the nearby NGC 1947 Group which is part of the Southern Supercluster.
NGC 2082 is host to an irregular bulge that is host to many star forming regions that are interspersed with dust. It is thought that the star formation occurring in the center of the galaxy is the result of gas inflow to the center. Surrounding the center of NGC 2082, the spiral arms of the galaxy are irregular and reach close to the center. The galaxy is host to a nuclear star cluster with an estimated mass of 3 × 106 M☉, and a supermassive black hole with an estimated mass 6.2 × 106 M☉. It is also home to a population of 27 known globular clusters.
One supernova has been observed in NGC 2082. SN 1992ba (Type II, mag. 14) was discovered by Robert Evans on 30 September 1992.
See also
List of NGC objects (1001–2000)
References
External links
2082
Dorado
Discoveries by John Herschel
Astronomical objects discovered in 1834
Barred spiral galaxies
017609
NGC 1947 Group
05415-6419
086- G 021 | NGC 2082 | Astronomy | 293 |
66,539,073 | https://en.wikipedia.org/wiki/TIC%20168789840 | TIC 168789840, also known as TYC 7037-89-1, is a stellar system with six stars. Three pairs of binary stars circle a common barycenter. While other systems with three pairs of stars have been discovered, this was the first system where the stars can be observed eclipsing one another, as the Earth lies approximately on their planes of rotation.
Discovery
The Transiting Exoplanet Survey Satellite identified that the star system consisted of six eclipsing stars. The discovery was announced in January 2021. It is approximately from Earth, in the constellation Eridanus, west of the river asterism's sharpest bend, Upsilon2 Eridani, often called Theemin. To be seen the group needs strong magnification from Earth as is much fainter than red clump giant star Theemin and is about nine times further away.
Orbits
Two sets of the binaries co-orbit relatively closely, while the third pair of stars takes 2,000 years to orbit the entire system barycenter. The inner A pair and C pair orbit each other in 3.7 years. These are, as taken from the paired B stars, about away (specifically the mean telescopic separation is ) and the three lettered pairs, as groups, have been resolved (the three gaps made out). From A pair to C pair is calculated to be () apart, which means this gap should be resolvable using speckle interferometry which has not yet been achieved.
Note, the three binaries (here close pairs) A, B, and C are resolved only as systems, the pairs being just (), (), and () apart, respectively.
According to Jeanette Kazmierczak of NASA's Goddard Space Flight Center:
Stellar characteristics
The primary stars of all three close binaries are slightly hotter and brighter than the Sun, while the secondary stars are much cooler and dimmer. Because the two closely bound pairs are so close, only the third, more distant pair could have planets. The primaries are all beginning to evolve away from the main sequence, while the less massive and longer-lived secondaries are all still firmly on the main sequence and fusing hydrogen in their cores.
See also
Castor (star) – the second-brightest (apparent) "star" in Gemini, likewise a (double-double)-double system
References
6
Astronomical objects discovered in 2021
Eridanus (constellation)
Eclipsing binaries | TIC 168789840 | Astronomy | 516 |
8,870,657 | https://en.wikipedia.org/wiki/Wat%27s%20Dyke | Wat's Dyke () is a linear earthwork running through the northern Welsh Marches from Basingwerk Abbey on the River Dee estuary, passing east of Oswestry and on to Maesbury in Shropshire, England. It runs generally parallel to Offa's Dyke, sometimes within a few yards but never more than away. It now appears insignificant and is visible in some places as a raised hedgerow and in others no more than a cropmark. The ditch has long since been filled in and the bank ploughed away, but originally it was a considerable construction, considered to be strategically more sophisticated than Offa's Dyke. The date of construction is disputed, ranging from sub-Roman to the early ninth century.
Construction and siting
It consists of the usual bank and ditch of an ancient dyke, with the ditch on the western side, meaning that the dyke faces Wales and by implication can be seen as protecting the English lands to the east. The placement of the dyke in the terrain also shows that care was taken to provide clear views to the west and to use local features to the best defensive advantage.
A section of the dyke extends north and south from Old Oswestry, an Iron Age hill fort.
Dating controversy
The dyke was previously thought to date to the early 8th century, constructed by Æthelbald, king of Mercia, who reigned from 716 to 757. Æthelbald's successor, Offa, built the dyke which carries his name at some point during his reign (757 to 796).
Excavations in the 1990s at Maes-y-Clawdd near Oswestry uncovered the remains of a small fire site together with eroded shards of Romano-British pottery and quantities of charcoal, which have been dated to between 411 and 561 AD (centered around 446 AD). This evidence would seem to place the building of the dyke in the era of the post-Roman kingdom whose capital was at Wroxeter (just south of modern-day Shrewsbury) about to the east.
The dating of the fire site and hence the dyke has been disputed, and it has been suggested that owing to the difficulties inherent in radiocarbon dating, this single date cannot be fully trusted and also that the dyke could easily have been built on top of the fire site at a later date.
Excavations in 2006 suggested a much later date of 792–852, and the earlier date is now thought to relate to a fire site of a sub-Roman earthwork which preceded the actual dyke. It has been tentatively suggested that the likely context for construction is in the 820s, when the Mercian king Coenwulf was fighting against a resurgent Welsh threat.
Wat's Dyke Way
The approximate line of the earthwork is followed by the Wat's Dyke Way, a waymarked long-distance path running for from Llanymynech in Powys to Basingwerk Abbey on the River Dee near Holywell. It was opened in 2007.
See also
Wansdyke, a similar earthwork created during sub-Roman decades in Wiltshire and Somerset
Scots' Dike, a linear earthwork constructed in 1552 to mark the division of the Debatable Lands and thereby settle the exact boundary between the Kingdoms of Scotland and England, on the Anglo-Scottish border
Black Pig's Dyke in Ireland
Broadclough Dykes in Lancashire
References
Further reading
Blake, Steve and Scott, Lloyd (2003): The Keys to Avalon: The True Location of Arthur’s Kingdom Revealed. Revised Edition, published by Rider.
Hannaford, H. R. (1998): "Archaeological Excavations on Wat’s Dyke at Maes-y-Clawdd," Archaeology Service, Shropshire County Council, report no. 132, December 1997.
Worthington, Margaret (1997): '"Wat’s Dyke: An Archaeological and Historical Enigma," Bulletin John Rylands Library, Manchester, Vol 79, no. 3, 1997. Reprinted in Offa's Dyke Journal, vol. 1, 2019, pp. 58–79
External links
www.geograph.co.uk – photos of Wat's Dyke today
Anglo-Saxon sites in England
Anglo-Saxon sites in Wales
Archaeological sites in Powys
Fortifications in England
Fortifications in Wales
History of Shropshire
Archaeological sites in Shropshire
England–Wales border
Ancient dikes
Fortification lines
Scheduled monuments in Flintshire
Linear earthworks | Wat's Dyke | Engineering | 889 |
34,162,981 | https://en.wikipedia.org/wiki/Global%20Electronics%20Council | Founded in 2005, the Global Electronics Council (GEC), formerly known as the Green Electronics Council, is a US-based environmental non-profit organization and mission to, "create a world where only sustainable technology is bought and sold".
EPEAT
GEC operates the Electronic Product Environmental Assessment Tool (EPEAT) system, which was designed to assist in the purchasing of "greener" PCs and displays, imaging equipment and televisions. The EPEAT system evaluates electronics on more than 50 environmental criteria, some required and some optional, that measure a product's efficiency and sustainability attributes. Products are rated Gold, Silver, or Bronze depending on how many criteria they meet. On 2007-01-24, President George W. Bush issued Executive Order 13423, which requires all United States Federal agencies to use EPEAT when purchasing computer systems. President Barack Obama issued a similar Executive Order in 2009. In 2012 EPEAT was released in India. By 2015, the number of registered green devices had risen by 108%.
In partnership with the Yale Center for Green Chemistry and Engineering, in September of 2008 GEC held a Forum for Sustainable Information and Communication Technologies (ICT) at Yale.
Catalyst Award
Green Electronics Council hosts and presents the annual Catalyst Award for "Practical projects whose impact can inspire further innovation in the electronics space." In 2015 Dell received an award for their innovations in environmental safety of electronic production. During the 2014 calendar year Dell used 5000 tons of recycled plastic in its production of 34 products. Other notable nominees included Hewlett-Packard, Toshiba, and Arrow Electronics.
Emerging Green Conference
Emerging Green Conference is an annual event organized by Green Electronics Council, where technology leaders meet to "explore sustainability issues throughout the lifecycle of electronics." The latest gathering happened in September 2015 where over 30 companies and organizations attended a three-day event at The Nines Hotel in Portland, Oregon.
Board of directors
Mark Buckley - Founder, One Boat Collaborative
Richard Crespin - Treasurer, Chief Executive Officer, Collaborate Up
Victor Duart - Former Manager Environmental Policy and Programs IBM EMEA, ASEAN, Japan
Daniel Kreeger - Co Founder & Executive Director, Association of Climate Change Officers
JaNay Queen Nazaire, PhD - Chief Strategy Officer, Living Cities
Jeanne Ng, PhD - Chairman, Hong Kong Institute of Qualified Environmental Professionals
Verena Radulovic - Vice President, Business Engagement, Center for Climate and Energy Solutions (C2ES)
Michael Robinson - Former Program Director, Global Supplier Diversity, IBM
Carl Smith - Former CEO & President of Call2Recycle Inc.
Trisa Thompson - Chair, Former Senior Vice President and Chief Responsibility Officer, Dell
See also
Green chemistry
One Laptop per Child
References
External links
Closing the Loop Electronics Design to Enhance Reuse/Recycling Value, 2009
The Connection Between Electronics and Sustainability
Environmental design
Electronics and the environment | Global Electronics Council | Engineering | 577 |
8,102,960 | https://en.wikipedia.org/wiki/Pearl%20River%20Tower | Pearl River Tower () is a 71-story, , clean technology neofuturistic skyscraper at the junction of Jinsui Road/Zhujiang Avenue West, Tianhe, Guangzhou, China. The tower's architecture and engineering were performed by Skidmore, Owings & Merrill with Adrian D. Smith and Gordon Gill (now at their own firm, AS+GG) as architects. Ground broke on the tower on 8 September 2006 and construction was completed in March 2011. It is intended for office use and is partially occupied by the China National Tobacco Corporation.
Architecture and design
The design of the Pearl River Tower is intended to minimise harm to the environment and it will extract energy from the natural and passive forces surrounding the building. Major accomplishments are the technological integration of form and function in a holistic approach to engineering and architectural design.
Sustainability
Energy-Saving Strategies
There were four steps in the approach to the Pearl River Tower's high-performance design: reduction, absorption, reclamation, and generation. These steps were put in place to achieve the goal of being a zero-energy building.
1. Reduction – This includes using low discharge ventilation, daylight responsive controls, radiant cooling, demand-based ventilation, and high-performance glazing.
2. Absorption – This includes using wind turbines, daylight responsive controls, and integrated Photovoltaics.
3. Reclamation – This stage includes using exhaust air heat recovery and chillers.
4. Generation – This final stage works to achieve the objective of being a zero-energy building by creating sufficient energy on-site through the use of microturbines.
Wind Turbines
The Pearl River Tower's design enables it to funnel wind through four large wind turbines to generate up to 15 times more energy than regular freestanding turbines.
Alongside creating the power required for the building to operate, another benefit to this design is that the wind is re-routed through the tower's ventilation system, filtering it through the ceiling and floor spaces throughout the building.
As well as being designed to tunnel the wind in the most efficient way, the tower was built so its widest side faces the direction of the wind, allowing it to capture the most wind possible and thus generate the most energy.
Winds in Guangzhou are relatively predictable, coming from the south for 80% of the year and coming from the north for the remaining 20%. This meant that the wind turbines' success could be maximized by considering the building's wind loads. To make the most of the prevailing wind direction, it was essential to place the building's broadest face at a perpendicular angle to the prevailing wind.
Turbine Usage
The building was designed to generate power as efficiently as possible. To achieve this goal, the Pearl River Tower was built to direct incoming wind into vents that lead to its turbines. Explicitly sculpted to guide wind into the turbines, this 71-story building works to ensure there is almost always clean energy being generated.
Cooling
Due to Guangzhou's climate, cooling is an essential part of keeping those within the building comfortable. As the heat increases to higher temperatures in the warmer months, the radiant ceiling system works to cool the office spaces. Another part of the cooling system design is the use of cladding on the broad faces of the building. Using cavities in the walls to trap hot air from the building's exterior, the air runs through the raised floor system and pushes the heat to specific areas where it can be collected and used effectively.
High-Efficiency Lighting
To avoid unnecessary energy expenditure, artificial lighting is only used in the building when necessary. When used, the highest-efficiency light bulbs on the market provide lighting for the building without requiring large amounts of electricity to function. The ceiling panels are built in a curved shape to allow the light to be dispersed evenly throughout the rooms, reducing the amount of power needed to light a given space fully.
Solar Heat
The Pearl River Tower has advanced double glazing that allows natural light to enter the building. There is a double-skin façade in place, meaning the walls have two layers: the outer skin has a high permeability for solar heat to allow it in, while the inner skin prevents solar gain. This is referred to as a double curtain wall. There is a ventilation corridor between the two layers. The layers automatically adjust to allow heat in or out as required. The result of this design is that the building is more thermochemically efficient. It helps keep the building at the desired temperature regardless of the weather without using large amounts of energy to pump artificially created hot or cold air into the building.
The heat that is trapped between the two skins rises, creating natural ventilation. Initially, the building design aimed to create a positive-energy building, meaning it would generate excess power that could be sold to the electrical grid. Complications with fire codes and regulations resulted in the original design being amended. In its final state, the 212,165 m2 building uses around 40% of the energy that a building of its size would typically use.
Triple Glazing
The glass on the exterior of the building has three layers of glazing applied to it. This glazing traps heat within the building, keeping it warmer during the winter. If the heat becomes excessive, it is easily vented out using the tower's built wind-powered ventilation system.
Photovoltaic Cells
The shading system on the exterior of the tower has photovoltaic cells incorporated in its design. The purpose of these cells is to absorb solar energy, much like the panels on the top of the tower. This has the effect of increasing the tower's ability to power itself with clean energy by reducing the need for it to draw from the local power grid. This adds to the tower's already considerable power-saving capabilities caused by the wind and solar power used in other parts of the building.
Reused Heating
When coolers are used for air conditioning, the hot water created as a byproduct is then used throughout the building. This reduces water demands and makes the building more sustainable overall.
Daylight Responsive Blinds
The blinds on the tower's exterior automatically open or close depending on the building's lighting needs. This maximizes the amount of light inside the building when needed while preventing an excess of light from blinding those insides. This is consistent with other sustainable, efficient aspects of the tower's design, as it prevents excessive artificial light usage and, in turn, prevents unnecessary power draw.
Influence
The Pearl River Tower is designed to be one of the most environmentally friendly buildings in the world.
Of Pearl River Tower’s accomplishments, many are related to the sustainable design features include:
The largest radiant-cooled office building in the world
Most energy efficient super-tall building in the world
The tower is an example of China’s goal to reduce the intensity of carbon dioxide emissions per unit of GDP in 2020 by 40 to 45 percent as compared to the level of 2005.
In a report presented at the 2008 Council on Tall Buildings and Urban Habitat it was reported that the building's sustainable design features will allow a 58% energy usage reduction when compared to similar stand alone buildings. The building would have been able to be carbon neutral and actually sell power back to the surrounding neighborhood if the micro-turbines had been installed into the building. However the local power company in Guangzhou does not allow independent energy producers to sell electricity back to the grid. Without the financial incentive to add the micro-turbines the developers removed them from the design. If they had been added excess power would have been produced from the building, at the very least, after office hours when the power needed by the building itself had been reduced.
Timeline
Fall 2005: Design Competition
8 September 2006: Ground Breaking Ceremony
November 2006: Enabling Works begin
18 July 2007: Public bidding for the construction
January 2008: Main Package construction begins
August 2008: Building Core construction reaches ground level
April 2009: 15th Level
November 2009: Glass curtainwall installation begins
December 2009: Building reaches upper wind turbine level
28 March 2010: Topped-out
References
External links
SOM's Pearl River Tower Page
AS+GG's Pearl River Tower Page
Consulting Services performed by RWDI
Skyscraper office buildings in Guangzhou
Office buildings completed in 2011
Skidmore, Owings & Merrill buildings
Sustainable building
2011 establishments in China
2011 in Guangzhou | Pearl River Tower | Engineering | 1,673 |
18,404,575 | https://en.wikipedia.org/wiki/HD%20211392 | HD 211392 is a suspected variable star in the equatorial constellation of Aquarius, positioned about 370 light-years away. With an apparent magnitude close to six, according to the Bortle scale it is just visible to the naked eye from dark, rural skies. It is a giant star with a stellar classification of K3III.
References
External links
SIMBAD database for HR 8500
Image of HD 211392 at Aladin previewer
Aquarius (constellation)
211392
K-type giants
8500
Suspected variables
110009
Durchmusterung objects | HD 211392 | Astronomy | 116 |
9,210,048 | https://en.wikipedia.org/wiki/Richard%20Crandall | Richard E. Crandall (December 29, 1947 – December 20, 2012) was an American physicist and computer scientist who made contributions to computational number theory.
Background
Crandall was born in Ann Arbor, Michigan, and spent two years at Caltech before transferring to Reed College in Portland, Oregon, where he graduated in physics and wrote his undergraduate thesis on randomness. He earned his Ph.D in theoretical physics from Massachusetts Institute of Technology.
Career
In 1978, he became a physics professor at Reed College, where he taught courses in experimental physics and computational physics for many years, ultimately becoming Vollum Professor of Science and director of the Center for Advanced Computation. He was also, at various times, Chief Scientist at NeXT, Inc., Chief Cryptographer and Distinguished Scientist at Apple, and head of Apple's Advanced Computation Group.
He was a pioneer in experimental mathematics. He developed the irrational base discrete weighted transform, a method of finding very large primes. He wrote several books and many scholarly papers on scientific programming and computation.
Crandall was awarded numerous patents for his work in the field of cryptography. He also wrote a poker program that could bluff. He owned and operated PSI Press, an online publishing company.
Personal life
Crandall was part Cherokee and proud of his Native heritage. He fronted a band called the Chameleons in 1981. He was working on an intellectual biography of Steve Jobs when he collapsed at his home in Portland, Oregon, from acute leukemia. He died 10 days later, on December 20, 2012, at the age of 64.
Books
Pascal Applications for the Sciences. John Wiley & Sons, New York 1983.
with M. M. Colgrove: Scientific Programming with Macintosh Pascal. John Wiley & Sons, New York 1986.
Mathematica for the Sciences, Addison-Wesley, Reading, Mass, 1991.
Projects in Scientific Computation. Springer 1994.
Topics in Advanced Scientific Computation. Springer 1996.
with M. Levich: A Network Orange. Springer 1997.
with C. Pomerance: Prime numbers: A Computational Perspective.'' Springer 2001.
References
External links
Professor Richard E. Crandall; many of Crandall's papers can be found here
Nicholas Wheeler, Remembering Prof. Crandall
Stephen Wolfram, Remembering Richard Crandall (1947-2012)
David Bailey and Jonathan Borwein, Mathematician/physicist/inventor Richard Crandall dies at 64
David Broadhurst, A prime puzzle in honor of Richard Crandall
1947 births
2012 deaths
Scientists from Ann Arbor, Michigan
Scientists from Portland, Oregon
20th-century American inventors
21st-century American inventors
American atheists
American computer scientists
Apple Inc. employees
Computational physicists
Deaths from leukemia in Oregon
Deaths from acute leukemia
Reed College faculty
Reed College alumni | Richard Crandall | Physics | 561 |
36,736,110 | https://en.wikipedia.org/wiki/Mail%20bag | A mail bag or mailbag can be one of several types of bags used for collecting or carrying different types of postal material.
References
Further reading
Bags
Philatelic terminology
Postal history
Postal services
Postal systems
United States Postal Service | Mail bag | Technology | 45 |
24,656,302 | https://en.wikipedia.org/wiki/Van%20Biesbroeck%27s%20star%20catalog | In 1961 the astronomer George Van Biesbroeck published a catalog of low luminosity stars discovered using the Otto Struve refractor telescope of the McDonald Observatory in Texas.
Survey and catalog
This survey is similar to earlier dim star surveys that were done by Max Wolf and Frank Elmore Ross but using later equipment and techniques that could detect even fainter stars. The stars in this catalog are all low luminosity stars that appear near known high proper motion stars in the telescope's field of view. The high proper motion indicates that the stars are close enough to Earth for a dim star to be seen with a large telescope. Presuming that these high proper motion stars might be binary stars with dim, previously undetected, companions, he took astrophotographs of the space around these stars looking for low luminosity stars that shared the high proper motions of the primary star. In general, the primary stars were too dim for a direct measurement of their distance by measuring their parallax at that time.
The stars in this catalog are identified by the designation; VB.
The original list ended at 12 with most identified as gravitationally bound in a binary or multiple star system. He also identified an additional 17 known high proper motion stars he later found to have low luminosity stars in the field of view of the bright star. Many of these stars were found to be optical double stars, not gravitationally bound to another star, and not known to be part of a binary system.
Most of the stars in this catalog are type K and M, red dwarf, stars, some with exceptionally low mass and luminosity. Three of the stars are type DC, white dwarf, stars.
The star from this catalog that is known to be closest to Earth is VB 10, at about 19 light years distance.
The original 1961 catalog has been updated for this table using the latest coordinates from SIMBAD as many of these objects have moved a considerable distance away from their 1961 positions. The original object designations for the primary stars are used but modified to be consistent with SIMBAD standards where necessary. One primary star was incorrectly identified and two primary stars could not be positively identified from the original catalog.
Significance
This catalog of stars is significant not only for the intrinsic features of the stars themselves but also for the stars proximity to Earth. These low mass, low luminosity stars close by are uniquely situated for exo-planetary searches using astrometry or optical methods. The low mass of the star enables observers on Earth to see a large motion of the star for a given planetary mass. The low luminosity of the stars makes a direct optical or infrared telescopic survey for orbiting objects, such as planets, near the star possible.
A notable member of this group is VB 10, discovered in 1944. This star was the least massive and dimmest star known at the time of its discovery. Based on a discovery claim made in 2009, VB 10 would have become the first star to have an extrasolar planet detected using astrometry, however this claim was later refuted.
See also
List of least massive stars
References
Astronomical catalogues of stars
Astronomical surveys | Van Biesbroeck's star catalog | Astronomy | 641 |
31,644,293 | https://en.wikipedia.org/wiki/NGC%203669 | NGC 3669 (other designations - UGC 6431, MCG 10-16-135, ZWG 291.67, IRAS11226+5759, PGC 35113) is a barred spiral galaxy in the constellation Ursa Major. It was discovered by William Herschel on March 18, 1790. The galaxy is seen edge-on and appears to be slightly warped. It has a small bulge.
It is a member of the NGC 3610 galaxy group. Members of the group that lie at a smaller projected distance from NGC 3669 include NGC 3674 and NGC 3683A 40–50 to the south and southeast and NGC 3613 and NGC 3619 40–50 to the west. Four satellite candidates have been detected near NGC 3669.
References
External links
Ursa Major
Barred spiral galaxies
3669
06431
35113 | NGC 3669 | Astronomy | 179 |
14,429,145 | https://en.wikipedia.org/wiki/GABBR2 | Gamma-aminobutyric acid (GABA) B receptor, 2 (GABAB2) is a G-protein coupled receptor subunit encoded by the GABBR2 gene in humans.
Function
B-type receptors for the neurotransmitter GABA (gamma-aminobutyric acid) inhibit neuronal activity through G protein-coupled second-messenger systems, which regulate the release of neurotransmitters and the activity of ion channels and adenylyl cyclase. See GABBR1 (MIM 603540) for additional background information on GABA-B receptors.[supplied by OMIM]
Interactions
GABBR2 has been shown to interact with GABBR1.
See also
GABAB receptor
References
Further reading
External links
G protein-coupled receptors | GABBR2 | Chemistry | 167 |
23,214,113 | https://en.wikipedia.org/wiki/Christian%20M%C3%B8ller | Christian Møller (22 December 1904, Hundslev, Als14 January 1980, Ordrup) was a Danish chemist and physicist who made fundamental contributions to the theory of relativity, theory of gravitation and quantum chemistry. He is known for Møller–Plesset perturbation theory and Møller scattering.
His suggestion in 1938 to Otto Frisch that the newly discovered process of nuclear fission might create surplus energy, led Frisch to conceive of the concept of the nuclear chain reaction, leading to the Frisch–Peierls memorandum, which kick-started the development of nuclear energy through the MAUD Committee and the Manhattan Project.
Møller was the director of the European Organization for Nuclear Research (CERN)'s Theoretical Study Group between 1954 and 1957 and later a member of the same organization's Scientific Policy Committee (1959-1972).
Møller tetrad theory of gravitation
In 1961, Møller showed that a tetrad description of gravitational fields allows a more rational treatment of the energy–momentum complex than in a theory based on the metric tensor alone. The advantage of using tetrads as gravitational variables was connected with the fact that this allowed to construct expressions for the energy-momentum complex which had more satisfactory transformation properties than in a purely metric formulation.
Supporting Chandrasekhar
Subrahmanyan Chandrasekhar came up with his theory of the Chandrasekhar limit for the maximum stable mass of a star, in 1930. This calculation was in opposition to Sir Arthur Eddington theories about stars. Eddington mocked Chandrasekhar various times and frequently campaigned against Chandrasekhar during conferences.
In 1935, Møller was the first to write a paper in collaboration with Chandrasekhar to criticise Eddington's theory. They wrote "we are quite unable to follow [Eddington's] arguments." They also proceeded to refute Eddington's follow up paper showing contradictions in his theory.
Books
The world and the atom, London, 1940.
The theory of relativity, Clarendon Press, Oxford, 1972.
A study in gravitational collapse, Kobenhavn : Munksgaard, 1975.
On the crisis in the theory of gravitation and a possible solution, Kobenhavn : Munksgaard, 1978.
Evidence for gravitational theories (ed.), Academic Press, 1963.
Interview with Dr. Christian Moller by Thomas S. Kuhn at Copenhagen July 29, 1963 Oral History Transcript — Dr. Christian Moller
See also
Born rigidity
Proper reference frame (flat spacetime)
References
20th-century Danish physicists
Danish chemists
Quantum physicists
1904 births
1980 deaths
Relativity theorists
People associated with CERN
People from Gentofte Municipality
Members of the Royal Swedish Academy of Sciences | Christian Møller | Physics | 567 |
1,841,324 | https://en.wikipedia.org/wiki/Alphonse%20and%20Gaston | Alphonse and Gaston is an American comic strip by Frederick Burr Opper, featuring a bumbling pair of Frenchmen with a penchant for politeness. It first appeared in William Randolph Hearst's newspaper, the New York Journal on September 22, 1901, with the title "Alphonse a la Carte and His Friend Gaston de Table d'Hote". The strip was later distributed by King Features Syndicate.
Characters and story
Their "'After you, Alphonse.', 'No, you first, my dear Gaston!'" routine ran for more than a decade. Alphonse is short and grotesque; Gaston is tall and grotesque. The premise is that both are extremely polite, constantly bowing and deferring to each other. Neither can ever do anything or go anywhere because each insists on letting the other precede him.
Though never a daily or even weekly feature, Alphonse and Gaston appeared on Sundays for several years. In addition to Hearst collections and licensed products, it was adapted into a stage play and several comedy shorts. In 1909, not-yet-famous director D.W. Griffith made a short (two-shot) split reel comedy for the Biograph company, featuring the characters, titled "The French Duel."
Crossovers
A prolific artist and writer, Opper's other creations included Willie, Hans from Hamburg, Our Antediluvian Ancestors, And Her Name Was Maud and Happy Hooligan. The characters would occasionally make guest appearances outside their own strips. On one occasion, And Her Name Was Maud featured an appearance by Alphonse and Gaston aboard a runaway sleigh, each of them bowing to the other in the seat.
Legacy
The strip faded from public view shortly after Opper's death in 1937, but the catchphrase "After you, my dear Alphonse" persisted.
The phrase "Alphonse-and-Gaston routine", or "Alphonse-Gaston Syndrome", indicates a situation wherein one party refuses to act until another party acts first. From a September 23, 2009, New York Times editorial: "For years, China and the United States have engaged in a dangerous Alphonse-and-Gaston routine, using each other's inaction to shirk their responsibility."
Alphonse and Gaston exchanges have also been employed by sportscasters during baseball broadcasts when two outfielders go after the ball and it falls in for a base hit. Also, the phrase has a specific meaning in baseball lingo: when two fielders allow a catchable ball to drop between them, it is known as "doing the Alphonse and Gaston."
The 1909 short farce-comedy Alphonse and Gaston by Frank Dumont is based around the characters.
The duo inspired the neologism "gastonette," coined by United States Circuit Judge Jon O. Newman in an opinion in In re McLean Industries Inc., 857 F.2d 88 (2d Cir. 1988): "We have no desire to consign the seamen to a jurisdictional limbo while the courts of two countries perform a gastonette, each awaiting a first move by the other."
The comic strip is referenced in Meyer Levin’s non-fiction novel Compulsion.
See also
Goofy Gophers
References
External links
Ohio Cartoonists: A Bicentennial Celebration: Frederick Burr Opper
American comic strips
American comics characters
1901 comics debuts
1937 comics endings
Fictional French people
Comic strip duos
Gag-a-day comics
Male characters in comics
Works about interpersonal relationships
Etiquette | Alphonse and Gaston | Biology | 726 |
1,915 | https://en.wikipedia.org/wiki/Antigen | In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.
Antigens can be proteins, peptides (amino acid chains), polysaccharides (chains of simple sugars), lipids, or nucleic acids. Antigens exist on normal cells, cancer cells, parasites, viruses, fungi, and bacteria.
Antigens are recognized by antigen receptors, including antibodies and T-cell receptors. Diverse antigen receptors are made by cells of the immune system so that each cell has a specificity for a single antigen. Upon exposure to an antigen, only the lymphocytes that recognize that antigen are activated and expanded, a process known as clonal selection. In most cases, antibodies are antigen-specific, meaning that an antibody can only react to and bind one specific antigen; in some instances, however, antibodies may cross-react to bind more than one antigen. The reaction between an antigen and an antibody is called the antigen-antibody reaction.
Antigen can originate either from within the body ("self-protein" or "self antigens") or from the external environment ("non-self"). The immune system identifies and attacks "non-self" external antigens. Antibodies usually do not react with self-antigens due to negative selection of T cells in the thymus and B cells in the bone marrow. The diseases in which antibodies react with self antigens and damage the body's own cells are called autoimmune diseases.
Vaccines are examples of antigens in an immunogenic form, which are intentionally administered to a recipient to induce the memory function of the adaptive immune system towards antigens of the pathogen invading that recipient. The vaccine for seasonal influenza is a common example.
Etymology
Paul Ehrlich coined the term antibody () in his side-chain theory at the end of the 19th century. In 1899, Ladislas Deutsch (László Detre) named the hypothetical substances halfway between bacterial constituents and antibodies "antigenic or immunogenic substances" (). He originally believed those substances to be precursors of antibodies, just as a zymogen is a precursor of an enzyme. But, by 1903, he understood that an antigen induces the production of immune bodies (antibodies) and wrote that the word antigen is a contraction of antisomatogen (). The Oxford English Dictionary indicates that the logical construction should be "anti(body)-gen".
The term originally referred to a substance that acts as an antibody generator.
Terminology
Epitope – the distinct surface features of an antigen, its antigenic determinant.Antigenic molecules, normally "large" biological polymers, usually present surface features that can act as points of interaction for specific antibodies. Any such feature constitutes an epitope. Most antigens have the potential to be bound by multiple antibodies, each of which is specific to one of the antigen's epitopes. Using the "lock and key" metaphor, the antigen can be seen as a string of keys (epitopes) each of which matches a different lock (antibody). Different antibody idiotypes, each have distinctly formed complementarity-determining regions.
Allergen – A substance capable of causing an allergic reaction. The (detrimental) reaction may result after exposure via ingestion, inhalation, injection, or contact with skin.
Superantigen – A class of antigens that cause non-specific activation of T-cells, resulting in polyclonal T-cell activation and massive cytokine release.
Tolerogen – A substance that invokes a specific immune non-responsiveness due to its molecular form. If its molecular form is changed, a tolerogen can become an immunogen.
Immunoglobulin-binding protein – Proteins such as protein A, protein G, and protein L that are capable of binding to antibodies at positions outside of the antigen-binding site. While antigens are the "target" of antibodies, immunoglobulin-binding proteins "attack" antibodies.
T-dependent antigen – Antigens that require the assistance of T cells to induce the formation of specific antibodies.
T-independent antigen – Antigens that stimulate B cells directly.
Immunodominant antigens – Antigens that dominate (over all others from a pathogen) in their ability to produce an immune response. T cell responses typically are directed against a relatively few immunodominant epitopes, although in some cases (e.g., infection with the malaria pathogen Plasmodium spp.) it is dispersed over a relatively large number of parasite antigens.
Antigen-presenting cells present antigens in the form of peptides on histocompatibility molecules. The T cells selectively recognize the antigens; depending on the antigen and the type of the histocompatibility molecule, different types of T cells will be activated. For T-cell receptor (TCR) recognition, the peptide must be processed into small fragments inside the cell and presented by a major histocompatibility complex (MHC). The antigen cannot elicit the immune response without the help of an immunologic adjuvant. Similarly, the adjuvant component of vaccines plays an essential role in the activation of the innate immune system.
An immunogen is an antigen substance (or adduct) that is able to trigger a humoral (innate) or cell-mediated immune response. It first initiates an innate immune response, which then causes the activation of the adaptive immune response. An antigen binds the highly variable immunoreceptor products (B-cell receptor or T-cell receptor) once these have been generated. Immunogens are those antigens, termed immunogenic, capable of inducing an immune response.
At the molecular level, an antigen can be characterized by its ability to bind to an antibody's paratopes. Different antibodies have the potential to discriminate among specific epitopes present on the antigen surface. A hapten is a small molecule that can only induce an immune response when attached to a larger carrier molecule, such as a protein. Antigens can be proteins, polysaccharides, lipids, nucleic acids or other biomolecules. This includes parts (coats, capsules, cell walls, flagella, fimbriae, and toxins) of bacteria, viruses, and other microorganisms. Non-microbial non-self antigens can include pollen, egg white, and proteins from transplanted tissues and organs or on the surface of transfused blood cells.
Sources
Antigens can be classified according to their source.
Exogenous antigens
Exogenous antigens are antigens that have entered the body from the outside, for example, by inhalation, ingestion or injection. The immune system's response to exogenous antigens is often subclinical. By endocytosis or phagocytosis, exogenous antigens are taken into the antigen-presenting cells (APCs) and processed into fragments. APCs then present the fragments to T helper cells (CD4+) by the use of class II histocompatibility molecules on their surface. Some T cells are specific for the peptide:MHC complex. They become activated and start to secrete cytokines, substances that activate cytotoxic T lymphocytes (CTL), antibody-secreting B cells, macrophages and other particles.
Some antigens start out as exogenous and later become endogenous (for example, intracellular viruses). Intracellular antigens can be returned to circulation upon the destruction of the infected cell.
Endogenous antigens
Endogenous antigens are generated within normal cells as a result of normal cell metabolism, or because of viral or intracellular bacterial infection. The fragments are then presented on the cell surface in the complex with MHC class I molecules. If activated cytotoxic CD8+ T cells recognize them, the T cells secrete various toxins that cause the lysis or apoptosis of the infected cell. In order to keep the cytotoxic cells from killing cells just for presenting self-proteins, the cytotoxic cells (self-reactive T cells) are deleted as a result of tolerance (negative selection). Endogenous antigens include xenogenic (heterologous), autologous and idiotypic or allogenic (homologous) antigens. Sometimes antigens are part of the host itself in an autoimmune disease.
Autoantigens
An autoantigen is usually a self-protein or protein complex (and sometimes DNA or RNA) that is recognized by the immune system of patients with a specific autoimmune disease. Under normal conditions, these self-proteins should not be the target of the immune system, but in autoimmune diseases, their associated T cells are not deleted and instead attack.
Neoantigens
Neoantigens are those that are entirely absent from the normal human genome. As compared with nonmutated self-proteins, neoantigens are of relevance to tumor control, as the quality of the T cell pool that is available for these antigens is not affected by central T cell tolerance. Technology to systematically analyze T cell reactivity against neoantigens became available only recently. Neoantigens can be directly detected and quantified.
Viral antigens
For virus-associated tumors, such as cervical cancer and a subset of head and neck cancers, epitopes derived from viral open reading frames contribute to the pool of neoantigens.
Tumor antigens
Tumor antigens are those antigens that are presented by MHC class I or MHC class II molecules on the surface of tumor cells. Antigens found only on such cells are called tumor-specific antigens (TSAs) and generally result from a tumor-specific mutation. More common are antigens that are presented by tumor cells and normal cells, called tumor-associated antigens (TAAs). Cytotoxic T lymphocytes that recognize these antigens may be able to destroy tumor cells.
Tumor antigens can appear on the surface of the tumor in the form of, for example, a mutated receptor, in which case they are recognized by B cells.
For human tumors without a viral etiology, novel peptides (neo-epitopes) are created by tumor-specific DNA alterations.
Process
A large fraction of human tumor mutations are effectively patient-specific. Therefore, neoantigens may also be based on individual tumor genomes. Deep-sequencing technologies can identify mutations within the protein-coding part of the genome (the exome) and predict potential neoantigens. In mice models, for all novel protein sequences, potential MHC-binding peptides were predicted. The resulting set of potential neoantigens was used to assess T cell reactivity. Exome–based analyses were exploited in a clinical setting, to assess reactivity in patients treated by either tumor-infiltrating lymphocyte (TIL) cell therapy or checkpoint blockade. Neoantigen identification was successful for multiple experimental model systems and human malignancies.
The false-negative rate of cancer exome sequencing is low—i.e.: the majority of neoantigens occur within exonic sequence with sufficient coverage. However, the vast majority of mutations within expressed genes do not produce neoantigens that are recognized by autologous T cells.
As of 2015 mass spectrometry resolution is insufficient to exclude many false positives from the pool of peptides that may be presented by MHC molecules. Instead, algorithms are used to identify the most likely candidates. These algorithms consider factors such as the likelihood of proteasomal processing, transport into the endoplasmic reticulum, affinity for the relevant MHC class I alleles and gene expression or protein translation levels.
The majority of human neoantigens identified in unbiased screens display a high predicted MHC binding affinity. Minor histocompatibility antigens, a conceptually similar antigen class are also correctly identified by MHC binding algorithms. Another potential filter examines whether the mutation is expected to improve MHC binding. The nature of the central TCR-exposed residues of MHC-bound peptides is associated with peptide immunogenicity.
Nativity
A native antigen is an antigen that is not yet processed by an APC to smaller parts. T cells cannot bind native antigens, but require that they be processed by APCs, whereas B cells can be activated by native ones.
Antigenic specificity
Antigenic specificity is the ability of the host cells to recognize an antigen specifically as a unique molecular entity and distinguish it from another with exquisite precision. Antigen specificity is due primarily to the side-chain conformations of the antigen. It is measurable and need not be linear or of a rate-limited step or equation. Both T cells and B cells are cellular components of adaptive immunity.
See also
References
Immune system
Biomolecules | Antigen | Chemistry,Biology | 2,732 |
2,829,558 | https://en.wikipedia.org/wiki/Female%20hysteria | Female hysteria was once a common medical diagnosis for women. It was described as exhibiting a wide array of symptoms, including anxiety, shortness of breath, fainting, nervousness, exaggerated and impulsive sexual desire, insomnia, fluid retention, heaviness in the abdomen, irritability, loss of appetite for food or sex, sexually impulsive behavior, and a "tendency to cause trouble for others". It is no longer recognized by medical authorities as a medical disorder. Its diagnosis and treatment were routine for hundreds of years in Western Europe.
In extreme cases, the woman may have been forced to enter an insane asylum or to undergo surgical hysterectomy.
In Western medicine, hysteria was considered both common and chronic among women. Though it was categorized as a disease at the time, modern day analyses suggest that hysteria's symptoms can be explained by the normal fluctuations of women's sexuality.
Early history
The history of hysteria diagnoses can be traced to ancient times. Dating back to 1900 BC in ancient Egypt, the first descriptions of hysteria within the female body were found recorded on the Kahun Papyri. In this culture, the womb was thought capable of affecting much of the rest of the body, but "there is no warrant for the fanciful view that the ancient Egyptians believed that a variety of bodily complaints were due to an animate, wandering womb". In this time, the medical issue of uterine prolapse was also known.
In ancient Greece, wandering womb was described in the gynecological treatise of the Hippocratic Corpus, "Diseases of Women", which dates back to the 5th and 4th centuries BC. Plato's dialogue Timaeus compares a woman's uterus to a living creature that wanders throughout a woman's body, "blocking passages, obstructing breathing, and causing disease". Aretaeus of Cappadocia described the uterus as "an animal within an animal" (less emotively, "a living thing inside a living thing"), which causes symptoms by wandering around a woman's body putting pressure on other organs.
The standard cure for this "hysterical suffocation" was scent therapy, in which good smells were placed under a woman's genitals and bad odors at the nose. It was thought that fumigating the body with special fragrances would draw the uterus back to its natural spot in the female body. Foul smells applied to the nose would drive it down, and pleasant scents at the vulva would attract it. Sneezing could be also induced to drive the uterus back to its correct place.
The concept of a pathological "wandering womb" was later viewed as the source of the term hysteria, which stems from the Greek cognate of uterus, ὑστέρα (hystera), although the word hysteria does not feature in ancient Greek medicine: 'the noun is not used in this period'.
Timaeus also argued that the uterus is "sad and unfortunate" when it does not join with a male or bear a child; thus, participating in sexual intercourse was an accepted treatment.
While in the Hippocratic texts a wide range of women were susceptible – including in particular the childless – Galen in the 2nd century omitted the childless and saw the most vulnerable group as "widows, and particularly those who previously menstruated regularly, had been pregnant and were eager to have intercourse, but were now deprived of all this" (On the Affected Parts, 6.5). He also denied that the womb could "move from one place to another like a wandering animal". His treatments included scent therapy and sexual intercourse, but also rubbing ointments into the external genitalia; this was to be performed by midwives, not physicians.
While most Hippocratic writers saw the retention of menstrual blood in the womb as a key problem, for Galen, even more serious was the retention of "female seed". This was believed to be thinner than male seed and could be retained in the womb. Hysteria was referred to as "the widow's disease", because the female semen was believed to turn venomous if not released through regular climax or intercourse. If the patient was married, this could be completed by intercourse with their spouse.
Middle Ages, Renaissance, and the early modern period
Through the Middle Ages, another cause of dramatic symptoms could be found: demonic possession. It was thought that demoniacal forces were attracted to those who were prone to melancholy, particularly single women and the elderly. Undiagnosable or incurable patients who were subsequently thought to have been possessed by the devil often exhibited symptoms that would indicate mental illness in modern day. After the 17th century, the correlation of demonic possession and hysteria were gradually discarded and instead was described as behavioral deviance, a medical issue.
In the 16th and 17th centuries, hysteria was still believed to be due to the retention of humour or fluids in the uterus, sexual deprivation, or by the tendency of the uterus to wander around the female body causing irritability and suffocation. Marriage, and regular sexual encounters with her husband, were still the most highly recommended long-term course of treatment for a woman with hysteria to purge the uterus of any built-up fluid. Self treatment such as masturbation, was not recommended and was also considered taboo. Semen was also thought to have healing properties, and physicians regarded all contraceptive practices as injurious to women. Giovanni Matteo Ferrari da Gradi cited marriage and childbearing as a cure for the disease. If pleasure was obtained from them, then hysteria could be cured. If a woman was unmarried, or widowed, manual stimulation by a midwife involving certain oils and scents was recommended to purge the uterus of any fluid retention. Lack of marriage was also thought to be the cause of most melancholy in single women, such as nuns or widows. Studies of the causes and effects of hysteria were continued in the 16th and 17th century by medical professionals such as Ambroise Pare, Thomas Sydenham, and Abraham Zacuto, who published their findings furthering medical knowledge of the disease, and informing treatment. Physician Abraham Zacuto writes in his Praxis Medica Admiranda from 1637:
There was continued debate about whether it was morally acceptable for a physician to remove excess female seed through genital manipulation of the female patient; Pieter van Foreest (Forestus) and Giovanni Matteo da Grado (Gradus) insisted on using midwives as intermediaries, and regarded the treatment as the last resort.
18th century
In the 18th century, hysteria slowly became associated with mechanisms in the brain rather than the uterus. This is also when it was noted both men and women could contract hysteria. French physician Philippe Pinel freed hysteria patients detained in Paris' Salpêtrière sanatorium on the basis that kindness and sensitivity were needed to formulate good care.
Another French physician, Francois de Sauvages de La Croix believed some common signs of female hysteria were "tears and laughter, oscitation [yawning], pandiculation (stretching and yawning), suffocating angina (chest pain) or dyspnea (shortness of breath), dysphagia (difficulty swallowing), delirium, a close and driving pulse, a swollen abdomen, cold extremities, and abundant and clear urine."
Anton Mesmer, a German physician, came up with the theory of “animal magnetism”, later referred to as mesmerism. Mesmer saw “animal magnetism” as energy that flowed through the nervous system. He would try to manipulate that “energy” to relieve his patients of hysteria. One of the methods he used was having his patients hold onto metal rods that were electrically charged. Mesmer's findings on "animal magnetism" were later discredited.
19th century
Jean-Martin Charcot argued that hysteria derived from a neurological disorder and asserted that it was more common in men than women. Charcot's theories of hysteria being a physical condition of the mind and not of the body led to a more scientific and analytical approach to hysteria in the 19th century. He dispelled the beliefs that hysteria had anything to do with the supernatural and attempted to define it medically. Charcot's use of photography, and the resulting concretization of women's expressions of health and distress, continued to influence women's experiences of seeking healthcare. Though older ideas persisted during this era, over time female hysteria began to be thought of less as a physical ailment and more of a psychological one.
George Beard, a physician who cataloged an incomplete list including 75 pages of possible symptoms of hysteria, claimed that almost any ailment could fit the diagnosis. Physicians thought that the stress associated with the typical female life at the time caused civilized women to be both more susceptible to nervous disorders and to develop faulty reproductive tracts. One American physician expressed pleasure in the fact that the country was "catching up" to Europe in the prevalence of hysteria.
In 1875, Edward Hammond Clarke wrote “Sex in Education”, a book discussing his views on men and women's education. Clarke believed that if women were educated, the energy in their bodies would go to the brain instead of the reproductive organs, hindering childbirth. He cited clothing, food, exercise, and education as causes of “Leucorrhoea, amenorrhea, dysmenorrhea, chronic and acute ovaritis, prolapsis utari, hysteria, neuralgia”. Clarke believed that men came into the world fully developed, while women did not, and that imposing men's education on women would worsen their problem. His views were condemned by many women's organizations.
According to Pierre Roussel and Jean-Jacques Rousseau, femininity was a natural and essential desire for women: "Femininity is for both authors an essential nature, with defined functions, and the disease is explained by the non-fulfillment of natural desire." It was during the Industrial Revolution and the major development of cities and modern lifestyles that disruption of this natural appetite was thought to cause lethargy or melancholy, leading to hysteria. At the time female patients sought medical practitioners for the treatment of hysteria with massage. The rate of hysteria was so great in the industrial period that women were prone to carry smelling salts about their person in case they swooned, reminiscent of Hippocrates' theory of using odors to coerce the uterus back into place. For physicians, manual massage treatment was becoming laborious and time-consuming, and they were seeking a way to increase productivity.
Rachel Maines hypothesized that physicians from the classical era until the early 20th century commonly treated hysteria by manually stimulating the genitals of female patients to the point of orgasm, which was denominated "hysterical paroxysm", and that the inconvenience of this may have motivated the original development of and market for the vibrator. Other hysteria treatments included pregnancy, marriage, heterosexual sex, and the application of smelling oils on female genitals. Maines's theory that hysteria was treated by manually stimulating female patients' genitalia to orgasm is widely repeated in the literature on female anatomy and sexuality. However, some historians dispute Maines's claims regarding the prevalence of this treatment for hysteria and its relevance to the invention of the vibrator, describing them as a distortion or overgeneralization of the evidence. In 2018, Hallie Lieberman and Eric Schatzberg of Georgia Institute of Technology challenged Maines's claims for the use of electromechanical vibrators to treat hysteria in the 19th century. Maines stated that her theory of the prevalence of masturbation for hysteria and its relevance to the invention of the vibrator is a hypothesis and not proven fact.
Frederick Hollick was a firm believer that a main cause of hysteria was licentiousness present in women.
20th century
In the 1910s, psychiatrist L. E. Emerson was heavily involved in treating patients of hysteria at the Boston Psychopathic Hospital. Emerson published case studies on his patients, who were often "young, single, native-born, and white" and either had been raped or had a lack of healthy sexual relationships. One of his more famous works was a case study of a woman called "Miss A". In the study, Emerson summarized the patient's experience with sexual violence, which he said that most women with hysteria had encountered. Miss A practiced self harm, which Emerson deduced to be a release for the sexual assault she had previously experienced and a substitute for masturbation. Another case study was of Sally Hollis, a woman who often viewed her experience with sexual assault in terms of her own failures and female aggression. Believing the roots of hysteria lay in sexual conflict, Emerson noted the theme of lack of sexual knowledge amongst these women, viewing them as repressed. Their sexual ignorance ranged from lack of knowledge about menstruation to conception to the process of giving birth.
Some women purposefully sought out the "hysteric" diagnosis because they believed it could provide an answer to what they were experiencing. Most of the patients that Emerson saw were single because they were either young or had purposefully avoided men. Author Elizabeth Lunbeck wrote that these women typically fell into three categories. They either withdrew from the heterosexual sphere entirely despite wanting to participate; they experienced something that was sexually unwanted but would experience guilt over what happened like Sally Hollis; or they were haunted by their sexual traumas in the past. As hysteria was becoming a more prominent diagnosis amongst women, police began treating any report for sexual assault or rape with skepticism, with the common belief at the time being that "sexual assault is physically impossible without consent".
Freud and decline of diagnosis
During the early 20th century, the number of women diagnosed with female hysteria sharply declined. Some medical authors claim that the decline was due to gaining a greater understanding of the psychology behind conversion disorders such as hysteria. The understanding of the field of psychiatry was becoming more nuanced at the time, with Sigmund Freud's introduction of the theory of psychoanalysis and his other ideas surrounding women and their sexuality.
With so many possible symptoms, historically hysteria was considered a catch-all diagnosis that any unidentifiable ailment could be assigned. As diagnostic techniques improved, the number of ambiguous cases that might have been attributed to hysteria declined. For instance, before the introduction of electroencephalography, epilepsy was frequently confused with hysteria.
Sigmund Freud claimed that hysteria was not physical at all but rather an internal emotional condition brought on by trauma that could affect both men and women and prevented them from enjoying sex in the normal way. This would later lead to Freud's development of the Oedipus complex, which connotes femininity as a failure, or lack of masculinity. Although some earlier studies had posited that men were also prone to hysteria, over time, the condition was related mainly to issues of femininity as the continued study of hysteria took place only in women.
Many cases that had previously been labeled hysteria were reclassified by Freud as anxiety neuroses. It was Freud's theory that hysteria may have been related to the unconscious mind and separate from the conscious mind or the ego. He was convinced that deep conflicts in the mind, some concerning instinctual drives for sex and aggression, were driving the behavior of those with hysteria. The illness of hysteria is an "expression of the impossibility of the fulfillment of the sexual drive because of reminiscence of the Oedipal conflict". This hypothesis is a driving force behind the psychological theory of psychoanalysis, as a way to help patients that had been diagnosed with hysteria reduce internal conflicts causing physical and emotional suffering.
New theories relating to hysteria came from speculation; doctors and physicians could not connect symptoms to the disorder, causing it to decline rapidly as a diagnosis. Hysteria was officially removed from the DSM in 1980.
Today, female hysteria is no longer a recognized illness, but different manifestations of hysteria are recognized in other conditions such as schizophrenia, borderline personality disorder, conversion disorder, and anxiety attacks.
Relationship with women's rights and feminism
In the 1980s, feminists began to reclaim the term "hysteria," using it as a symbol of the systematic oppression of women and reclaiming the term for themselves. The idea of hysteria became an embodiment of the oppressions against women, especially among sex-positive feminists, who believed sexual repression being considered hysteria was a form of oppression. The idea stemmed from the belief that hysteria was a kind of pre-feminist rebellion against the oppressive defined social roles placed upon women. Feminist writers such as Catherine Clément and Hélène Cixous wrote in The Newly Born Woman from a place of opposition to the theories proposed in psychoanalytical works. Clément, Cixous and other feminist writers pushed back against the notion that socially constructed femininities and hysteria are natural to being female. Feminist social historians of both sexes argue that hysteria is caused by women's oppressed social roles, rather than by their bodies or psyches.
Representation in creative works
Charlotte Perkins Gilman
"The Yellow Wallpaper" is a short story by Charlotte Perkins Gilman that demonstrates the mistreatment of hysteria and illuminates the deep-rooted misogynistic systems that existed at the time. Published in 1892, this piece is an early example of media in which medical care is interrogated through a feminist lens. In the story, the female protagonist is confined to an upstairs room at the instruction of her husband, who is a physician, which paradoxically worsens her condition. Over the course of her lengthy confinement, the protagonist becomes obsessed with the yellow wallpaper and believes she can see a woman inside it as her mental state deteriorates.
Safe
The 1995 film Safe explores the harmful effects of sexism in healthcare on the psychological and physical health of women and girls. It explores the connections between mental illness, the misdiagnosis of mental illness when physical conditions proved difficult to diagnose, feminism, and healthcare disparities that result from deep-rooted sexism in the medical industry.
See also
The Cancer Journals
Degeneration theory
Gender bias in medical diagnosis
Hysterical contagion
Male hysteria
Mass hysteria
Mass psychogenic illness
Premenstrual dysphoric disorder
Race suicide
Safe (1995 film)
Social hygiene
Vapours
The Yellow Wallpaper
References
Further reading
Kapsalis, Terri (2008). The Hysterical Alphabet. WhiteWalls. .
External links
Erika Kinetz, "Is Hysteria Real? Brain Images Say Yes" (The New York Times)
Female Hysteria During Victorian Era: Its Symptoms, Diagnosis & Treatment/Cures
Anxiety
Chauvinism
Freudian psychology
Human sexuality
Hysteria
Misogyny
Obsolete medical theories
Hysteria, female
Pejorative terms for women
Pseudoscience
Social problems in medicine
Stereotypes of women
Uterus | Female hysteria | Biology | 3,892 |
361,245 | https://en.wikipedia.org/wiki/Torque%20wrench | A torque wrench is a tool used to apply a specific torque to a fastener such as a nut, bolt, or lag screw. It is usually in the form of a socket wrench with an indicating scale, or an internal mechanism which will indicate (as by 'clicking', a specific movement of the tool handle in relation to the tool head) when a specified (adjustable) torque value has been reached during application.
A torque wrench is used where the tightness of screws and bolts is a crucial parameter of assembly or adjustment. It allows the operator to set the torque applied to the fastener to meet the specification for a particular application. This permits proper tension and loading of all parts.
Torque screwdrivers and torque wrenches have similar purposes and may have similar mechanisms.
History
The first patent for a torque wrench was filed by John H. Sharp of Chicago in 1931. This wrench was referred to as a torque measuring wrench and would be classified today as an indicating torque wrench.
In 1935, Conrad Bahr and George Pfefferle patented an adjustable ratcheting torque wrench. The tool featured audible feedback and restriction of back-ratcheting movement when the desired torque was reached. Bahr, who worked for the New York City Water Department, was frustrated at the inconsistent tightness of flange bolts he found while attending to his work. He claimed to have invented the first torque limiting tool in 1918 to alleviate these problems. Bahr's partner, Pfefferle, was an engineer for S.R. Dresser Manufacturing Co and held several patents.
Types
Beam
The most basic form of torque wrench consists of two beams. The first is a lever used to apply the torque to the fastener being tightened and serves also as the handle of the tool. When force is applied to the handle it will deflect predictably and proportionally with said force in accordance with Hooke's law. The second beam is only attached at one end to the wrench head and free on its other, this serves as the indicator beam. Both of these beams run parallel to each other when the tool is at rest, with the indicator beam usually on top. The indicator beam's free end is free to travel over a calibrated scale attached to the lever or handle, marked in units of torque. When the wrench is used to apply torque, the lever bends and the indicating beam stays straight. Thus, the end of the indicating beam points to the magnitude of the torque that is currently being applied. This type of wrench is simple, inherently accurate, and inexpensive.
The beam type torque wrench was developed in between late 1920s and early 1930s by Walter Percy Chrysler for the Chrysler Corporation and a company known as Micromatic Hone. Paul Allen Sturtevant—a sales representative for the Cedar Rapids Engineering Company at that time—was licensed by Chrysler to manufacture his invention. Sturtevant patented the torque wrench in 1938 and became the first individual to sell torque wrenches.
A more sophisticated variation of the beam type torque wrench has a dial gauge indicator on its body that can be configured to give a visual or electrical indication when a preset torque is reached.
Deflecting beam
The dual-signal deflecting beam torque wrench was patented by the Australian Warren and Brown company in 1948. It employs the principle of applying torque to a deflecting beam rather than a coil spring. This is claimed to help prolong the accuracy of the wrench throughout its working life, with a greater safety margin on maximum loading and provides more consistent and accurate readings throughout the range of each wrench. The operator can both hear the signal click and see (and feel) a physical indicator when the desired torque is reached.
The wrench functions in the same general way as an ordinary beam torque wrench. There are two beams both connected to the head end but only one through which torque is applied. The load carrying beam is straight and runs from head to handle, it deflects when torque is applied. The other beam (indicating beam) runs directly above the deflecting beam for about half of the length then bends away to the side at an angle from the deflecting beam. The indicating beam retains its orientation and shape during operation. Because of this, there is relative displacement between the two beams. The deflecting beam torque wrench differs from the ordinary beam torque wrench in how it utilizes this relative displacement. Attached to the deflecting beam is a scale and onto that is fitted a wedge which can be slid along the length of the scale parallel to the flexing beam. This wedge is used to set the desired torque. Directly facing this wedge is the side of the angled indicating beam. From this side protrudes a pin, which acts as a trigger for another pin, the latter pin is spring loaded, and fires out of the end of the indicating beam once the trigger pin contacts the adjustable wedge. This firing makes a loud click and gives a visual and tactile indication that the desired torque has been met. The indicator pin can be reset by simply pressing it back into the indicating beam.
Slipper
A slipper type torque wrench consists of a roller and cam (or similar) mechanism. The cam is attached to the driving head, the roller pushes against the cam locking it in place with a specific force which is provided by a spring (which is in many cases adjustable). If a torque which is able to defeat the holding force of the roller and spring is applied, the wrench will slip and no more torque will be applied to the bolt. A slipper torque wrench will not overtighten the fastener by continuing to apply torque beyond a predetermined limit.
Click
A more sophisticated method of presetting torque is with a calibrated clutch mechanism. One common form uses a ball detent and spring, with the spring preloaded by an adjustable screw thread, calibrated in torque units. The ball detent transmits force until the preset torque is reached, at which point the force exerted by the spring is overcome and the ball "clicks" out of its socket. This design yields greater precision as well as giving tactile and audible feedback. The wrench will not start slipping once the desired torque is reached, it will only click and bend slightly at the head; the operator can continue to apply torque to the wrench without any additional action or warnings from the wrench.
A number of variations of this design exist for different applications and different torque ranges. A modification of this design is used in some drills to prevent gouging the heads of screws while tightening them. The drill will start slipping once the desired torque is reached.
"No-hub" wrench
These are specialized torque wrenches used by plumbers to tighten the clamping bands on hubless soil pipe couplings. They are usually T-handled wrenches with a one-way combination ratchet and clutch. They are preset to a fixed torque designed to secure the coupling adequately but insufficient to damage it.
Electronic torque wrenches
With electronic (indicating) torque wrenches, measurement is by means of a strain gauge attached to the torsion rod. The signal generated by the transducer is converted to the required unit of torque (e.g. N·m or lbf·ft) and shown on the digital display. A number of different joints (measurement details or limit values) can be stored. These programmed limit values are then permanently displayed during the tightening process by means of LEDs or the display. At the same time, this generation of torque wrenches can store all the measurements made in an internal readings memory. This reading's memory can then be easily transferred to a PC via the interface (RS232) or printed. A popular application of this kind of torque wrench is for in-process documentation or quality assurance purposes. Typical accuracy level would be ±0.5% to 4%.
Interchangeable Head Torque Wrenches
Interchangeable head torque wrenches are designed to connect several different types of wrench heads, thereby reducing the number of torque wrenches needed. These wrenches are ideal for applications that require multiple fastening tools. They typically have a standard mounting interface that allows for quick changeover from one wrench head to another while ensuring that the torque applied remains accurate. Common interface sizes include 9×12mm and 12×14mm, and interchangeable heads include open-end, ring-end, adjustable, ratchet, etc.
Programmable electronic torque / angle wrenches
Torque measurement is conducted in the same way as with an electronic torque wrench but the tightening angle from the snug point or threshold is also measured. The angle is measured by an angle sensor or electronic gyroscope. The angle measurement process enables joints which have already been tightened to be recognized. The inbuilt readings memory enables measurements to be statistically evaluated. Tightening curves can be analyzed using the software via the integrated tightening-curve system (force/path graph). This type of torque wrench can also be used to determine breakaway torque, prevail torque and the final torque of a tightening job. Thanks to a special measuring process, it is also possible to display the yield point (yield controlled tightening). This design of torque wrench is highly popular with automotive manufacturers for documenting tightening processes requiring both torque and angle control because, in these cases, a defined angle has to be applied to the fastener on top of the prescribed torque (e.g. + 90° – here the means the snug point/threshold and +90° indicates that an additional angle has to be applied after the threshold).
In 1995, Saltus-Werk Max Forst GmbH applied for an international patent for the first electronic torque wrench with angle measurement which did not require a reference arm.
Mechatronic torque wrenches
Torque measurement is achieved in the same way as with a click-type torque wrench but, at the same time, the torque is measured as a digital reading (click and final torque) as with an electronic torque wrench. This is, therefore, a combination of electronic and mechanical measurements. All the measurements are transferred and documented via wireless data transmission. Users will know they have achieved the desired torque setting when the wrench "beeps".
Torque wrench standardization
ISO
The International Organization for Standardization maintains standard ISO 6789. This standard covers the construction and calibration of hand-operated torque tools. They define two types of torque tool encompassing twelve classes, these are given by the table below. Also given is the percentage allowable deviation from the desired torque.
The ISO standard also states that even when overloaded by 25% of the maximum rating, the tool should remain reliably usable after being re-calibrated. Re-calibration for tools used within their specified limits should occur after 5000 cycles of torquing or 12 months, whichever is soonest. In cases where the tool is in use in an organization which has its own quality control procedures, then the calibration schedule can be arranged according to company standards.
Tools should be marked with their torque range and the unit of torque as well as the direction of operation for unidirectional tools and the maker's mark. If a calibration certificate is provided, the tool must be marked with a serial number that matches the certificate or a calibration laboratory should give the tool a reference number corresponding with the tool's calibration certificate.
ASME
The American Society of Mechanical Engineers maintains standard ASME B107.300. This standard has the same type designation as the ISO standard with the addition of the type 3, (limiting) torque tool. This type will release the drive once the desired torque is met so that no more torque can be applied. This standard, however, uses different class designations within each type as well as additional style and design variants within each class. The standard also separates manual and electronic tools into different sections and designations. The ASME and ISO standards cannot be considered compatible. The table below gives some of the types and tolerances specified by the standard for manual torque tools.
Tools should be marked with the model number of the tool, the unit of torque and the maker's mark. For unidirectional tools, the word "TORQUES" or "TORQUE" and the direction of operation must also be marked.
Using torque wrenches
Precision
Click type torque wrenches are precise when properly calibrated—however the more complex mechanism can result in loss of calibration sooner than the beam type, where there is little to no malfunction, (however the thin indicator rod can be accidentally bent out of true). Beam type torque wrenches are impossible to use in situations where the scale cannot be directly read—and these situations are common in automotive applications. The scale on a beam type wrench is prone to parallax error, as a result of the large distance between indicator arm and scale (on some older designs). There is also the issue of increased user error with the beam type—the torque has to be read at every use and the operator must use caution to apply loads only at the floating handle's pivot point. Dual-beam or "flat" beam versions reduce the tendency for the pointer to rub, as do low-friction pointers.
Extensions
The use of cheater bars that extend from the handle end can damage the wrench, so only manufacturer specified equipment should be used.
Using socket extensions requires no adjustment of the torque setting.
Using a crow's foot or similar extension requires the use of the following equation:
using a combination of handle and crow's foot extensions requires the use of the following equation:
where:
is the wrench indicated torque (setting torque),
is the desired torque,
is the length of the torque wrench, from the handle to the center of the head,
is the length of the crow's foot extension, from the center of the torque wrench head to the center line of the bolt,
is the length of the handle extension, from the extension end to the torque wrench handle.
These equations only apply if the extension is colinear with the length of the torque wrench. In other cases, the distance from the torque wrench's head to the bolt's head, as if it were in line, should be used. If the extension is set at 90° then no adjustment is required. These methods are not recommended except for extreme circumstances.
Storage
For click (or other micrometer) types, when not in use, the force acting on the spring should be removed by setting the scale to its minimum rated value in order to prevent permanent set in the spring.
Never set a micrometer style torque wrench to zero as the internal mechanism requires a small amount of tension in order to prevent components shifting and reduction of accuracy.
Calibration
As with any precision tool, torque wrenches should be periodically re-calibrated. As previously stated, according to ISO standards calibration should happen every 5000 operations or every year, whichever comes first. It is possible that torque wrenches can fall up to 10% out of calibration in the first year of use.
Calibration, when performed by a specialist service which follows ISO standards, follows a specific process and constraints. The operation requires specialist torque wrench calibration equipment with an accuracy of ±1% or better. The temperature of the area where calibration is being performed should be between 18 °C and 28 °C with no more than a 1 °C fluctuation and the relative humidity should not exceed 90%.
Before any calibration work can be done, the tool should be preloaded and torqued without measure according to its type. The tool is then connected to the tester and force is applied to the handle (at no more than 10° from perpendicular) for values of 20%, 60% and 100% of the maximum torque and repeated according to their class. The force should be applied slowly and without jerky or irregular motion. The table below gives more specifics regarding the pattern of testing for each class of torque wrench.
While professional calibration is recommended, for some people it would be out of their means. It is possible to calibrate a torque wrench in the home shop or garage. The process generally requires that a certain mass is attached to a lever arm and the torque wrench is set to the appropriate torque to lift said mass. The error within the tool can be calculated and the tool may be able to be altered or any work done adjusted for this error.
See also
Dental torque wrench
Foot-pound force
Battery torque wrench
Hydraulic torque wrench
Impact wrench
Micrometer
Newton metre
Torque converter
Torque limiter
Torque screwdriver
Torque tester
Torsion (mechanics)
Wrench
Notes
References
External links
American inventions
Wrench
Wrenches | Torque wrench | Physics | 3,443 |
2,705,889 | https://en.wikipedia.org/wiki/System%20requirements%20specification | A System Requirements Specification (SysRS) (abbreviated SysRS to be distinct from a software requirements specification (SRS)) is a structured collection of information that embodies the requirements of a system.
A business analyst (BA), sometimes titled system analyst, is responsible for analyzing the business needs of their clients and stakeholders to help identify business problems and propose solutions. Within the systems development life cycle domain, the BA typically performs a liaison function between the business side of an enterprise and the information technology department or external service providers.
See also
Business analysis
Business process reengineering
Business requirements
Concept of operations
Data modeling
Information technology
Process modeling
Requirement
Requirements analysis
Software requirements specification
Systems analysis
Use case
References
External links
IEEE Guide for Developing System Requirements Specifications (IEEE Std 1233, 1999 Edition)
IEEE Guide for Developing System Requirements Specifications (IEEE Std 1233, 1998 Edition)
DAU description System/Subsystem Specification, Data Item Description (SSS-DID)
System Requirements Specification for STEWARDS example SRS at USDA
Software engineering
Systems analysis
Systems engineering
ru:Техническое задание | System requirements specification | Technology,Engineering | 235 |
3,644,442 | https://en.wikipedia.org/wiki/Moon%20pool | A moon pool is an equipment deployment and retrieval feature used by marine drilling platforms, drillships, diving support vessels, fishing vessels, marine research and underwater exploration or research vessels, and underwater habitats. It is also known as a wet porch. It is an opening found in the floor or base of the hull, platform, or chamber giving access to the water below. Because of its stable location, it safely allows technicians or researchers to lower tools and instruments into the sea.
Moon pools also provide shelter and protection so that even if the ship is in high seas or surrounded by ice, researchers can work in comfort rather than on a deck exposed to the elements. A moon pool also allows divers, diving bells, ROVs, or small submersible craft to enter or leave the water easily and in a more protected environment.
Moon pools can be used in chambers below sea level, especially for the use of scuba divers, and their design requires more complex consideration of air and water pressure acting on the moon pool surface.
Origins
Moon pools were first used in the oil drilling industry given the remote offshore locations of oil fields (e.g. sea or in lakes). It has been used for drilling, production, storage and offloading to smaller vessels for transportation of oil. It is also built to pass drilling equipments into the water from a platform or drillship. A moonpool supports the need of drill pipes to run vertically through the structure or hull.
The Glomar Explorer
The Hughes Glomar Explorer was a , ship constructed by the United States in the early 1970s for the recovery of a sunken Soviet submarine from the Pacific seabed. The design of the ship was broadly inspired by oil drilling ships and included a moon pool measuring , into which the submarine was to be recovered, with the bottom of the moon pool then closed off by two gates that would allow the recovered vessel to be examined under cover and in dry conditions. This was a singular use of a moon pool and also possibly the largest dedicated moon pool constructed to date.
In underwater habitats
Very deep moon pools are used in underwater habitats—submerged chambers used by divers engaged in underwater research, exploration, marine salvage, and recreation. In this case, shown in part D of the diagram, there is no dry access between the chamber and the sea surface, and the moon pool is the only entry or exit to the chamber. Submerged chambers provide dry areas for work and rest without the need to ascend to the surface. This kind of submerged chamber uses the same principles as the diving bell, except they are fixed to the seafloor and may be called a wet porch, wet room, or wet bell. Sometimes the term moon pool is used to mean the complete chamber, not just the opening in the bottom and the air–water interface.
The alternative to a moon pool in an underwater habitat is the lock-out chamber, which is essentially like a fixed submarine, maintaining internal air pressures lower than ambient sea pressure down to one atmosphere, with an airlock to enable entry and exit underwater. Underwater habitats may have connected chambers with moon pools and lock-out chambers.
Examples of underwater habitats with moon pools
SEALAB II (US Navy)
The Florida laboratory Aquarius, where it is called a wet porch
In fishing vessels
Moon pools are becoming increasingly used on longline fishing vessels to allow for hauling of the gear in worse weather conditions. They also reduce the exposure of fish to air, improving quality. Along with bird scaring lines, shooting and hauling gear from a moon pool reduces the risk of fish falling off or being predated by birds.
Gallery of types
See also
References
Diving support equipment
Marine architecture
Oil platforms
Shipbuilding
Underwater habitats | Moon pool | Chemistry,Engineering | 739 |
37,579,306 | https://en.wikipedia.org/wiki/Ctenocheloides%20attenboroughi | Ctenocheloides attenboroughi is a species of ghost shrimp in the family Ctenochelidae. It was described in 2010 and named in honour of the British natural history broadcaster Sir David Attenborough. It is known from a single female specimen collected in shallow water on the north-western coast of Madagascar. The total length of the specimen is , with a carapace long.
Distribution
The single known specimen of Ctenocheloides was collected in 2008 from a "large, mud-cemented piece of rubble", dredged from a bay near Hell-Ville, Nosy Bé, in north-western Madagascar. The piece of rubble was lying at a depth of in a bay filled with mangroves.
References
Axiidea
Species known from a single specimen | Ctenocheloides attenboroughi | Biology | 158 |
32,659,088 | https://en.wikipedia.org/wiki/Favard%27s%20theorem | In mathematics, Favard's theorem, also called the Shohat–Favard theorem, states that a sequence of polynomials satisfying a suitable three-term recurrence relation is a sequence of orthogonal polynomials. The theorem was introduced in the theory of orthogonal polynomials by and , though essentially the same theorem was used by Stieltjes in the theory of continued fractions many years before Favard's paper, and was rediscovered several times by other authors before Favard's work.
Statement
Suppose that y0 = 1, y1, ... is a sequence of polynomials where yn has degree n. If this is a sequence of orthogonal polynomials for some positive weight function then it satisfies a 3-term recurrence relation. Favard's theorem is roughly a converse of this, and states that if these polynomials satisfy a 3-term recurrence relation of the form
for some numbers cn and dn,
then the polynomials yn form an orthogonal sequence for some linear functional Λ with Λ(1)=1; in other words Λ(ymyn) = 0 if m ≠ n.
The linear functional Λ is unique, and is given by Λ(1) = 1, Λ(yn) = 0 if n > 0.
The functional Λ satisfies Λ(y) = dn Λ(y), which implies that Λ is positive definite if (and only if) the numbers cn are real and the numbers dn are positive.
See also
Jacobi operator
James Alexander Shohat
Jean Favard
References
Reprinted by Dover 2011,
Orthogonal polynomials
Theorems in approximation theory | Favard's theorem | Mathematics | 329 |
44,614,166 | https://en.wikipedia.org/wiki/Aquifer%20properties | The aquifer properties of the aquifer essentially depend upon the composition of the aquifer. The most important properties of the aquifer are porosity and specific yield which in turn give its capacity to release the water in the pores and its ability to transmit the flow with ease.
Porosity
In soil mechanics and hydrology, porosity is defined as the ratio of volume of voids to the total volume of porous medium. Mathematically it can be represented by the equation expressed as
where is void ratio, is porosity, VV is the volume of void-space (air and water), VS is the volume of solids, and VT is the total or bulk volume of medium.
The significance of the porosity is that it gives the idea of water storage capacity of the aquifer. Qualitatively, porosity less than 5% is considered to be small, between 5 and 20% as medium and the percentage exceeding 20% is considered as large.
Specific yield
Porosity gives a measure of the water storage capability of soil but not all the water present in the soil pores is available for extraction by pumping for the use of humans or draining by gravity. The pores in the soil hold back sufficient quantity of water on account of forces like surface tension and molecular attraction. Hence the actual amount of water that can be extracted from the unit volume of aquifer by pumping or under the action of gravity is called as specific yield. The fraction of water held back in the aquifer is known as specific retention. Thus it can be said that porosity is the sum of specific yield and specific retention. Specific yield of soils differ from each other in the sense that some soil types have strong molecular attraction with the water held in their pores while others have less. It is found experimentally that cohesionless soils have high specific yield than cohesive soils because the former has significantly less molecular attraction then the latter. Coarse-grained soils or rocks such as coarse sandstone can have specific yields that are closer to their actual porosity in the range 20 to 35%. The case of fine grained materials is quite opposite to that range.
Porosity and Specific Yield of Soil Formation
In the table above, sand and gravel though having less porosity than clay yield much more than clay because of relatively less molecular attraction and coarse size of particles.
Specific retention division of subject water
References
Hydrology
Civil engineering | Aquifer properties | Chemistry,Engineering,Environmental_science | 491 |
6,394,469 | https://en.wikipedia.org/wiki/Germ-free%20animal | Germ-free organisms are multi-cellular organisms that have no microorganisms living in or on them. Such organisms are raised using various methods to control their exposure to viral, bacterial or parasitic agents. When known microbiota are introduced to a germ-free organism, it usually is referred to as a gnotobiotic organism, however technically speaking, germ-free organisms are also gnotobiotic because the status of their microbial community is known. Due to lacking a microbiome, many germ-free organisms exhibit health deficits such as defects in the immune system and difficulties with energy acquisition. Typically germ-free organisms are used in the study of a microbiome where careful control of outside contaminants is required.
Generation and cultivation
Germ-free organisms are generated by a variety of different means, but a common practice shared by many of them is some form of sterilization step followed by seclusion from the surrounding environment to prevent contamination.
Poultry
Germ-free poultry typically undergo multiple sterilization steps while still at the egg life-stage. This can involve either washing with bleach or an antibiotic solution to surface sterilize the egg. The eggs are then transferred to a sterile incubator where they are grown until hatching. Once hatched, they are provided with sterilized water and a gamma-irradiated feed. This prevents introduction of foreign microbes into their intestinal tracts. The incubators and animals' waste products are continuously monitored for possible contamination. Typically, when being used in experiments, a known microbiome is introduced to the animals at a few days of age. Contamination is still monitored and controlled for after this point, but the presence of microbes is expected.
Mice
Mice undergo a slightly different process due to lacking an egg life-stage. To create a germ-free mouse, an embryo is created through in vitro fertilization and then transplanted into a germ-free mother. If this method is not available, a mouse can be born through cesarean birth, but this comes with a higher risk of contamination. This process uses a non-germ-free mother which is sacrificed and sterilized before the pups' birth. After the cesarean birth, the pups must then be transferred to a sterile incubator with a germ-free mother for feeding and growth. These methods are only required for the generation of a germ-free mouse line. Once a line is generated, all progeny will be germ-free unless contaminated. These progeny can then be used for experimentation. Typically for experiments, each mouse is housed separately in a sterile isolator to prevent cross-contamination between mice. The mice are provided with sterilized food and water to prevent contamination. The sterilization methods can vary between experiments due to different diets or drugs the mice are exposed to. The isolators and waste products are continuously monitored for possible contamination to ensure complete sterility. As with poultry, a known microbiome can be introduced into the animals but contamination is still monitored for.
Nematodes
Nematodes can also be grown germ-free. Germ-free offspring of the nematode C. elegans, which is used in research, can be produced by rupturing adult worms to release eggs. The standard method for this is to introduce a population of adult worms to a bleach solution. This bleach solution ruptures the adult worms, breaking them down while simultaneously releasing and surface sterilizing any eggs. The sterilized eggs are washed and transferred to a plate of agar containing food for the worms. C. elegans consumes bacteria, so before the eggs can be transferred to the plate, the food must be killed by either heat or irradiation. This method for creating germ-free nematodes has the added benefit of age-synchronizing the worms, so that they are all of similar ages as they grow. Typically the worms will need to be transferred to a new plate as they consume all the food on the current plate, with each plate having been treated with heat or radiation as well. The plates can be protected from outside contamination by covering them and isolating them from possible contamination sources.
Plants
Seeds are surface sterilized with chemicals, such as ethanol or an antibiotic solution, to produce a germ-free plant. The seeds are then grown in water or other mediums until germination. After germination, the seeds are transferred to either sterile soil or soil with a specific microbiota for use in experiments. Seeds may also be transferred directly to soil and allowed to germinate. If the plants are transferred to sterile soil, typically there are two types of growth methods. The first is where the entire plant is kept sterile and in the other, only the root system is kept sterile. The method is chosen based on the requirements for the experiment. The plants are grown in isolators which are frequently checked for contamination along with the soil that the plants grow in.
Fruit flies
Fruit flies, specifically the Drosophila species, have been one of the most used model organisms. Drosophila species has mostly been used in the field of genetics. There are two main methods for yielding gnotobiotic or axenic flies. One of them is to collect the eggs and dechorionate them. A chorion is the outer membrane around the embryo. In aseptic conditions, the eggs are washed twice for 2.5 minutes each, in 0.6% sodium hypochlorite solution. They are then placed with the specimens cup in 90 ml of bleach. Following this, they are washed thrice in sterile water. The dechorionated eggs are then placed in vials containing sterile diet.
The second method is by the use of antibiotics. Media, such as standard yeast-cornmeal diet, is supplemented with streptomycin or a combination of antibiotics. The concentration of the antibiotic is 400 μg/ml. Once the yeast-cornmeal diet has cooled, 4 ml of solution containing 10g of streptomycin dissolved in 100 ml of ethanol is added per litre of food. The media is then poured into vials and the freshly harvested eggs are transferred into the vials.
Health effects on organism
Due to lacking a healthy microbiome, many germ-free organisms exhibit major health deficits. The methods used to produce germ-free organisms can also have negative side effects on the organism. Decreased hatching rates were observed in chicken eggs incubated with mercuric chloride, while treatment with peracetic acid did not cause a significant effect on hatching rates. The chickens also exhibited defects in small intestine growth and health. Germ-free mice have been shown to have defects in their immune system and energy uptake due to lacking a healthy microbiome. There is also strong evidence for interactions between the mouse microbiome and its brain development and health. Germ-free plants exhibit severe growth defects due to lacking symbionts that provide necessary nutrients to them.
Uses
Microbiome research
Germ-free animals are routinely used to establish causality in studies of the microbiome. This is done by comparing animals with a standard commensal gut microbiome to germ free, or by colonising a germ free animal with an organism of interest. The gut microbiota can vary between research facilities which can be a confounder in experiments and be a cause of lack of reproducibility. Several control microbiomes have been developed which correct the major health defects commonly present in germ free animals and can act as a reproducible control community. Germ free animals have been used to demonstrate a causal role for the gut microbiome in varied settings such as neural development, longevity, cancer immunotherapy, and numerous other health related contexts.
See also
Axenic culture
References
Animal models | Germ-free animal | Biology | 1,645 |
24,326,752 | https://en.wikipedia.org/wiki/C16H21NO3 | {{DISPLAYTITLE:C16H21NO3}}
The molecular formula C16H21NO3 (molar mass: 275.35 g/mol, exact mass: 275.1521 u) may refer to:
Datumetine
Homatropine
Methylenedioxypyrovalerone (MDPV)
Rolipram
Molecular formulas | C16H21NO3 | Physics,Chemistry | 76 |
33,024,211 | https://en.wikipedia.org/wiki/Fezakinumab | Fezakinumab is a human monoclonal antibody against interleukin-22, designed for the treatment of psoriasis and rheumatoid arthritis.
Research and development
Wyeth discovered and initially developed the drug, and clinical development continued after that company was acquired by Pfizer. Fezakinumab, in combination with methotrexate, completed a phase II trial in rheumatoid arthritis, but data were not released. A small phase II trial of fezakinumab showed significant improvement in the Scoring Atopic Dermatitis (SCORAD) score for patients with severe atopic dermatitis.
References
Drugs developed by Wyeth
Drugs developed by Pfizer
Abandoned drugs | Fezakinumab | Chemistry | 149 |
42,570,568 | https://en.wikipedia.org/wiki/Aplos%20Software | Aplos Software is a privately held company that specializes in software as a service for nonprofit organizations. Their primary focus is simple software to manage the essential nonprofit tasks of fund accounting, nonprofit tax preparation and donor management for small, mid-sized, and large non-profit organizations.
History
Aplos Software was founded in 2009 in Fresno, California by Dan Kelly and Tim Goetz, a certified public accountant. Tim Goetz previously served as an executive pastor of a church and helped found two nonprofits. He couldn't find the low-cost fund accounting solution he wanted for his nonprofits, so he joined with a Fresno-based investor that shared his vision to serve the nonprofit sector with simple, affordable software and founded Aplos Software.
After initially developing a desktop fund accounting software program, in 2011 Aplos Software launched its fund accounting software, Aplos Accounting, as an online product, also known as software as a service, tailored specifically to small and mid-sized non-profit organizations and religious corporations.
The company raised over $3.4 million in funding through an angel investor to expand the development of its web-based nonprofit software suite, $2 million of which was raised in 2014.
Aplos launched an integration with Church Community Builder, a church management platform in January 2016.
In February 2016, Aplos raised $4 million in additional funding through a private venture capital fund.
In June 2017, Aplos announced a merger with Portalbuzz, a membership management platform that specializes in software and website portals for service clubs.
Aplos and Gusto (software), a payroll and HR platform, launched an integrated solution for payroll and reimbursements to be tracked within the accounting of nonprofits and churches.
Key Areas of Development
Aplos Software focused its software on simplifying the primary back office tasks required to manage a nonprofit, private foundation, foundation (nonprofit), charitable organization or church.
Fund Accounting
Nonprofit fund accounting differs from business accounting because it is often necessary to track restricted and unrestricted funds separately. This often occurs when a donor or grant specifies that the organization must use the funds for a specific purpose. The accounting software must track how these funds were used and how much is available. Aplos first launched its online fund accounting software, Aplos Accounting, in 2011. The most popular competitive accounting product for small and mid-sized nonprofits is Quickbooks
In October 2012, Aplos Software launched Aplos Oversight, an online software which provides an administrator or accountant real-time access to the accounting of multiple organizations.
Form 990 Preparation
In summer of 2012, Aplos Software was approved as an IRS efile provider to submit IRS tax forms on behalf of tax-exempt organizations and in October 2012 launched Aplos e-File, a tax preparation and filing software for IRS Form 990-N. IRS Form 990-N is an annual electronic IRS filing for tax-exempt organizations with less than $50,000 in annual gross receipts. In 2013, Aplos added tax preparation and e-file software for IRS Form 990-EZ and its required schedules to Aplos e-File. IRS Form 990-EZ is the short form of the full Form 990 IRS tax forms and is available to organizations with up to $200,000 in gross receipts and $500,000 in assets.
Donor Management
Aplos Software also focused on expanding the fundraising and donation tracking aspects of its software since 2012 to make it more successful for the vertical market of nonprofits. It launched a contributions management module in 2012 that tracked donations within Aplos Accounting and created contribution statements, which are annual giving receipts required by the IRS. In July 2013 it began offering a donor management module, and in May 2017 it expanded on its module to launch a stand-alone product as Aplos Donor Management.
According to the Chronicle of Philanthropy, nonprofits are increasingly creating initiatives to accept donations online and growth in online giving outpaced traditional methods in 2012. To keep pace with the growing popularity and requests by its customers for an online giving platform, Aplos Software expanded its fundraising functionality in January 2014 by partnering with WePay, an online payment portal, to add the ability for nonprofits to accept online donations.
See also
Comparison of accounting software
Fund accounting
Non-profit organization
Alternative giving
Software as a service
IRS Form 990
References
External links
www.aplos.com
Non-profit technology
Cloud applications | Aplos Software | Technology | 887 |
12,200,538 | https://en.wikipedia.org/wiki/Nexus%20driver | A Nexus driver is a bus device driver that interfaces leaf drivers to a specific I/O bus and provides the low-level integration of this I/O bus.
In some systems, for example Solaris, drivers are organized into a tree structure. A driver that provides services to other drivers below it in the tree is called, in Solaris terminology, a nexus driver. A tree node with no children, a leaf node, is called a leaf driver.
References
Device drivers | Nexus driver | Technology | 97 |
9,318,403 | https://en.wikipedia.org/wiki/Markov%20brothers%27%20inequality | In mathematics, the Markov brothers' inequality is an inequality, proved in the 1890s by brothers Andrey Markov and Vladimir Markov, two Russian mathematicians. This inequality bounds the maximum of the derivatives of a polynomial on an interval in terms of the maximum of the polynomial. For k = 1 it was proved by Andrey Markov, and for k = 2,3,... by his brother Vladimir Markov.
The statement
Let P be a polynomial of degree ≤ n. Then for all nonnegative integers
This inequality is tight, as equality is attained for Chebyshev polynomials of the first kind.
Related inequalities
Bernstein's inequality (mathematical analysis)
Remez inequality
Applications
Markov's inequality is used to obtain lower bounds in computational complexity theory via the so-called "Polynomial Method".
References
Theorems in analysis
Inequalities | Markov brothers' inequality | Mathematics | 177 |
418,885 | https://en.wikipedia.org/wiki/The%20Machine%20Stops | "The Machine Stops" is a science fiction short story by E. M. Forster. After initial publication in The Oxford and Cambridge Review (November 1909), the story was republished in Forster's The Eternal Moment and Other Stories in 1928. After being voted one of the best novellas up to 1965, it was included that same year in the popular anthology Modern Short Stories. In 1973 it was also included in The Science Fiction Hall of Fame, Volume Two.
The story, set in a world where humanity lives underground and relies on a giant machine to provide its needs, predicted technologies similar to instant messaging and the Internet.
Plot summary
The story describes a world in which most of the human population has lost the ability to live on the surface of the Earth. Each individual now lives in isolation below ground in a standard room, with all bodily and spiritual needs met by the omnipotent, global Machine. Travel is permitted but is unpopular and rarely necessary. Communication is made via a kind of instant messaging/video conferencing machine with which people conduct their only activity: the sharing of ideas and what passes for knowledge.
The two main characters, Vashti and her son Kuno, live on opposite sides of the world. Vashti is content with her life, which, like most inhabitants of the world, she spends producing and endlessly discussing second-hand 'ideas'. Her son Kuno, however, is a sensualist and a rebel. He persuades a reluctant Vashti to endure the journey (and the resultant unwelcome personal interaction) to his room. There, he tells her of his disenchantment with the sanitised, mechanical world.
He confides to her that he has visited the surface of the Earth without permission and that he saw other humans living outside the world of the Machine. However, the Machine recaptures him, and he is threatened with 'Homelessness': expulsion from the underground environment and presumed death. Vashti, however, dismisses her son's concerns as dangerous madness and returns to her part of the world.
As time passes, and Vashti continues the routine of her daily life, there are two important developments. First, individuals are no longer permitted use of the respirators which are needed to visit the Earth's surface. Most welcome this development, as they are sceptical and fearful of first-hand experience and of those who desire it. Secondly, "Mechanism", a kind of religion, is established in which the Machine is the object of worship. People forget that humans created the Machine and treat it as a mystical entity whose needs supersede their own.
Those who do not accept the deity of the Machine are viewed as 'unmechanical' and threatened with Homelessness. The Mending Apparatus—the system charged with repairing defects that appear in the Machine proper—has also failed by this time, but concerns about this are dismissed in the context of the supposed omnipotence of the Machine itself.
During this time, Kuno is transferred to a room near Vashti's. He comes to believe that the Machine is breaking down and tells her cryptically "The Machine stops." Vashti continues with her life, but eventually defects begin to appear in the Machine. At first, humans accept the deteriorations as the whim of the Machine, to which they are now wholly subservient, but the situation continues to deteriorate as the knowledge of how to repair the Machine has been lost.
Finally, the Machine collapses, bringing 'civilization' down with it. Kuno comes to Vashti's ruined room. Before they both perish, they realise that humanity and its connection to the natural world are what truly matters, and that it will fall to the surface-dwellers who still exist to rebuild the human race and to prevent the mistake of the Machine from being repeated.
Themes
In the preface to his Collected Short Stories (1947), Forster wrote that "'The Machine Stops' is a reaction to one of the earlier heavens of H. G. Wells." In The Time Machine, Wells had pictured the childlike Eloi living the life of leisure of Greek gods while the working Morlocks lived underground and kept their whole idyllic existence going. In contrast to Wells' political commentary, Forster points to the technology itself as the ultimate controlling force.
Critical reception
The Fantasy Book Review calls The Machine Stops "dystopic and quite brilliant," noting, "In such a short novel The Machine Stops holds more horror than any number of gothic ghost stories. Everybody should read it, and consider how far we may go ourselves down the road of technological 'advancement' and forget what it truly means to be alive;" rating the story as 10 out of 10.
As well as Forster predicting globalisation, the Internet, video conferencing and other aspects of 21st-century reality, Will Gompertz, writing on the BBC website on 30 May 2020, observed, "'The Machine Stops' is not simply prescient; it is a jaw-droppingly, gob-smackingly, breathtakingly accurate literary description of lockdown life in 2020."
In 2010, Wired magazine's Randy Alfred wrote, "1909: E.M. Forster publishes 'The Machine Stops,' a chilling tale of a futuristic information-oriented society that grinds to a bloody halt, literally. Some aspects of the story no longer seem so distant in the future."
Adaptations
A television adaptation, directed by Philip Saville, was shown in the UK on 6 October 1966 as part of the second series of British science-fiction anthology TV series Out of the Unknown. It is one of only four episodes known to exist from the show's second series.
In 2001, BBC Radio 4 aired Gregory Norminton's adaptation as a radio play. Another radio adaptation, by Philip Franks, aired on Radio 4 on 19 June 2022.
Playwright Eric Coble's 2004 stage adaptation was broadcast on 16 November 2007 on WCPN 90.3 FM in Cleveland, Ohio.
TMS: The Machine Stops is a graphic novel series adaptation written by Michael Lent with art by Marc Rene, published by Alterna Comics in February 2014.
Playwright Neil Duffield's adaptation was staged at York Theatre Royal in May–June 2016.
Related works
Mad #1 (Oct–Nov 1952) featured "Blobs", a seven-page story drawn by Wallace Wood where two inhabitants of 1,000,000 AD discuss the history of man and his evolution into "blobs" totally dependent on the Machine.
Stephen Baxter's story "Glass Earth Inc.", which refers explicitly to "The Machine Stops", is included in the book Phase Space, published in 2003.
Isaac Asimov's second novel in the Robot Series, The Naked Sun (1957), takes place on a planet similar to the Earth seen in this story. On the Planet Solaria human colonists live isolated from one another, only viewing each other through holograms, and only have interactions with their robot retinues. After several centuries the humans have become so dependent on this practice it has become taboo to even be in the presence of another human being.
The song "The Machine Stops" by the band Level 42 not only shares the same title with the story but also has lyrics that echo Kuno's thoughts.
The band A Hope for Home based their song "The Machine Stops" on their album Realis on this story by Forster.
Both George Lucas's film THX 1138 (1971) and the original novel version of Logan's Run (1967) by William F. Nolan and George Clayton Johnson bear similarities to "The Machine Stops".
The space rock band Hawkwind released a concept album titled The Machine Stops in 2016 based on the story by Forster.
See also
1909 in science fiction
References
Further reading
Seegert, Alf (2010), "Technology and the Fleshly Interface in E. M. Forster's 'The Machine Stops'", Journal of Ecocriticism 2: 1.
Pordzik, Ralph. 2010. Closet fantasies and the future of desire in E. M. Forster's "The Machine Stops". English Literature in Transition 1880–1920 53, No. 1 (Winter): 54–74.
Wally Wood's version for Mad Magazine, 1952
External links
The Machine Stops and Other Stories by E. M. Forster, Rod Mengham Online text via Goodreads
Dystopian literature
Plays by Eric Coble
1909 short stories
Religion in science fiction
Short stories by E. M. Forster
Science fiction short stories
Works originally published in British magazines
Works originally published in literary magazines
Constable & Co. books
Fictional computers | The Machine Stops | Technology | 1,786 |
69,406,325 | https://en.wikipedia.org/wiki/Weather%20of%202019 | The following is a list of weather events in 2019.
Global conditions
2019 was Earth's second-warmest year on record, which goes back to 1880. It was the 43rd consecutive year of above-average temperatures. The year was 0.95 °C (1.71 °F) above the 20th century average, and 0.07 °C (0.04 °F) behind 2016, which was the warmest year on record. 2019 fell to the third-warmest year on record when the following year surpassed it. In 2019, Australia and the U.S. state of Alaska recorded their warmest years on record.
There is a previous El Niño episode continuing from last year, and new El Niño episode started this year, lasting until 2020.
Summary by weather type
Winter storms and cold waves
From January 16 to 19, a winter storm crosses the United States, killing ten. Then, from January 24 into February, a cold wave brought record low temperatures to the United States. Illinois set a statewide record low temperature. Twenty-two people die as a result of the cold. Then, in mid-March, another cross country storm came to the United States, which killed a man in Colorado, left 140,000 without power in Texas, and contributed to the 2019 Midwestern U.S. floods, which caused two deaths in Nebraska and one in Iowa. Another blizzard struck the United States in April 2019. In October 2019, record cold and near-record cold come down over the Pacific Northwest and Northern Plains. In particular, with a mean statewide temperature of , Idaho realized its coldest October on record. The next major winter storm in the United States came next season, when a cold wave that kills at least seven people. The last notable blizzard is the November 26 – December 3, 2019 North American blizzard. Eight people die due to the storm, and over 80,000 people in the New York Metropolitan Area lose power.
Floods
In late January and early February, the Australian city of Townsville experienced record flooding when a stalled but very active monsoon trough that was bought down by Tropical Low 13U, caused an overflowing of the Ross River Dam. Approximately 3300 homes were damaged by floodwaters, and about 1500 homes rendered uninhabitable. As many as 30,000 insurance claims were filed in the aftermath of the event, with damages estimated to be $1.243 billion AUD based on insurance losses. 5 deaths were attributed to the event. The event came after Townsville experienced a drought prior to the flooding. One year prior to the floods, the dam level was at 13%, and during the floods the dam peaked at 244%, before water was released.
Droughts, heat waves, and wildfires
Tornadoes
An EF4 tornado in Havana in January 2019, becomes the strongest in Cuba since 1940. Eight people are killed and 190 are injured. Later on February 23–24, a tornado outbreak across the United States kills one and causes $1.4 billion in damages. Then, on March 3, a deadly tornado outbreak spawns 41 tornadoes. One of them, the 2019 Beauregard tornado, becomes the deadliest tornado since the 2013 Moore tornado and kills 23 people, and injures 97. On March 31, a tornado strikes Nepal. This tornado is responsible for 28 deaths and $800,000 in damage. It was later identified as the first confirmed case of a tornado in Nepal. Then, on April 13–15, 2019, a tornado outbreak in the Southeastern United States kills three. A few days later, another tornado outbreak tied for Mississippi's largest tornado outbreak, As the squall line tracked east, numerous reports of damaging wind gusts were received across the Southeast United States. and also became Virginia's third largest outbreak in a single day. In the second half of May, the United States experienced a record breaking tornado outbreak sequence. On June 29, a rare hybrid tornado struck Allen, South Dakota. A few months later, an EF3 tornado in Dallas became the costliest tornado in Texas history. In November, another tornado outbreak caused a fatality in the Southeastern US. The death was due to an EF2 in Louisiana. The last major tornado outbreak of the year occurs on December 16–17, 2019, which cause 3 deaths, plus one non-tornadic.
Tropical cyclones
As the year began, five tropical cyclones that formed in 2018 were still active. Cyclone Penny was moving over Queensland, Cyclone Mona was developing in the eastern Australian region, a tropical depression and a tropical disturbance was in the South Pacific, and Tropical Storm Pabuk was in the South China Sea.
In the south-west Indian Ocean, there were 14 tropical cyclones, including several powerful cyclones. Cyclone Idai struck Mozambique in March and caused widespread flooding across southeast Africa. The cyclone killed at least 1,297 people, becoming one of the deadliest recorded tropical cyclones in Africa, with a damage total of over US$2 billion, the costliest cyclone on record in the basin. In April, Cyclone Kenneth struck northern Mozambique as the most intense storm on record to hit the country. It killed 52 people in the Comoros and Mozambique. In December, Cyclone Ambali attained 10 minute winds of 220 km/h (140 mph) after the most significant rapid deepening events ever recorded in the southern hemisphere. In the Australian region, there were 15 tropical cyclones, including Cyclone Veronica, which caused A$2 billion (US$1.4 billion) in damage when it struck Western Australia. There were 11 tropical cyclones in the South Pacific Ocean during the year. In the south Atlantic Ocean, there was a rare short-lived tropical storm – Iba – which formed in March off the coast of Brazil.
In the north-west Pacific Ocean, there were 49 tropical cyclones that formed after Pabuk. In August, Typhoon Lekima killed 105 people and caused CN¥65.37 billion (US$9.26 billion) in damage when it struck southeastern China. Also in August, Typhoon Faxai struck Japan, causing US$10 billion in damage, followed less than two months later by Typhoon Hagibis, which hit Tokyo. Hagibis killed 98 people and caused US$15 billion in damage. In the North Indian Ocean, there were 12 tropical cyclones, including Cyclone Pabuk, which moved from the South China Sea into the Bay of Bengal in early January. The season's strongest storm was Cyclone Kyarr in October, which attained winds of 240 km/h (150 mph) in the Arabian Sea. Also during the season, Cyclone Fani struck eastern India, killing 89 people and causing US$8.1 billion in damage.
In the north Atlantic Ocean, there were 18 tropical cyclones and two subtropical cyclones. In September, Hurricane Dorian became the strongest storm on record to hit The Bahamas, with 1 minute sustained winds of 185 mph (295 km/h). Dorian devastated the country as it moved slowly through the island group, causing US$3.4 billion in damage and at least 74 deaths, with hundreds missing. In September, Tropical Storm Imelda moved ashore southeastern Texas and left US$5 billion in damage after dropping of rainfall. Also in September, Hurricane Lorenzo attained 1 minute sustained winds of 160 mph (260 km/h) in the eastern Atlantic Ocean. Lorenzo capsized a ship, the Bourbon Rhode, killing 11 crew members, and the storm later struck the Azores, causing €330 million (US$367 million) in damage. In the north-east Pacific Ocean, there were 21 tropical cyclones.
Timeline
This is a timeline of weather events during 2019. Please note that entries might cross between months, however, all entries are listed by the month they started with an exception for Tropical Storm Pabuk which was ongoing when 2019 began. Dates listed in parentheses mean the start and end dates are not specifically listed in the articles.
January
December 31, 2018 – January 8, 2019 – Tropical Storm Pabuk, also referred to as Cyclonic Storm Pabuk, kills ten people and caused $157.2 million (2019 USD) in damage across the Natuna Islands, Vietnam, Malay Peninsula, Myanmar, Thailand, and the Andaman Islands.
January 16–21 – A winter storm strikes the United States, killing ten.
January 22–24 – Tropical Storm Eketsang kills 27 people and caused damage across Madagascar.
January 24 – Four tornadoes in Turkey killed four people and caused damage.
January 24 – February (14) – A cold wave across the American Midwest and Great Lakes region killed 22 people.
January 27 – A nighttime EF4 tornado in Havanna, Cuba kills eight people and injured 193 others. This was the strongest tornado to hit Cuba since 1940.
February
February 18 – March 2 – Typhoon Wutip, also known as Tropical Depression Betty, caused $3.3 million (2019 USD) in damage across Guam, the Federated States of Micronesia,and the Northern Mariana Islands.
February 23 – An EF3 tornado in Mississippi kills one person and injured 19 others.
March
March 3 – A severe and deadly tornado outbreak across the Southeastern United States results in 23 fatalities and 103 injuries from 41 tornadoes.
March 3 – An EF4 tornado during the Tornado outbreak of March 3 kills 23 people and injured 90 others and caused $1.75 million (2019 USD) in damage across its 68.73 mi (110.61 km) path.
March 4–21 – Cyclone Idai kills 1,303 with more than 2,262 missing and caused more than $2.2 billion (2019 USD) in damage across Mozambique, Malawi, northern Madagascar, and Zimbabwe. Idai is the deadliest tropical cyclone recorded in the South-West Indian Ocean basin and in the Southern Hemisphere, which includes the Australian, South Pacific, and South Atlantic basins, Idai ranks as the second-deadliest tropical cyclone on record.
March 8–16 – A blizzard, tornado outbreak, and floods across North America killed four people (1 blizzard and 3 flooding) and caused over 140,000 power outages. The storm system spawned 38 tornadoes and a wind gust of 109 mph (175 km/h) was recorded at Northeast Texas' Grand Prairie Airport.
March 8–24 – Cyclone Savannah kills ten people with one missing and caused $7.5 million (2019 USD) in damage across Bali, Java, Christmas Island, and the Cocos (Keeling) Islands.
March 15–26 – Cyclone Trevor caused $700,000 (2019 USD) in damage across Indonesia, Papua New Guinea, Queensland, and Northern Territory, Australia.
March 18–31 – Cyclone Veronica caused $1.65 billion (2019 USD) in damage across Timor and Western Australia, becoming the Fourth-costliest tropical cyclone in the Australian region basin.
March 19 - Monthly record highs were set across much of Alaska, British Columbia and Washington State. Seattle's high of was the warmest for the November to March period. Some places saw highs that would set records even in April.
March 31 – A deadly and powerful F4 Tornado hits Nepal which kills between 28 and 50 people and caused $800,000 (2019 USD) in damage. This was the first ever recorded tornado in Nepal.
April
April 4–6 – The Goseong Fire kills two people, injured 30 others, burned 1,307 acres, and caused $4.6 million (2019 USD) in damage in South Korea.
April 10–14 – A blizzard in the United States caused over 139,000 power outages and had wind gusts as high as 107 mph (172 km/h) at Pueblo West, Colorado.
April 13 – An EF3 tornado in China kills one person and injured five others.
April 13–15 – A tornado outbreak in the United States kills nine people (3 tornadic and 6 non-tornadic) and injured 65 others from 71 tornadoes.
April 17–19 – A tornado outbreak in the South Central and Southeastern United States kills four people (all non-tornadic) from 96 tornadoes.
April 21–29 – Cyclone Kenneth kills 52 people and caused $188 million (2019 USD) in damage across Seychelles, Comoros, Mayotte, northern Madagascar, northern Mozambique, southern Tanzania, and Malawi.
April 26 – May 5 – Cyclone Fani kills 89 people and caused $8.1 billion (2019 USD) in damage across Odisha, West Bengal, Andhra Pradesh, East India, Bangladesh, Bhutan, and Sri Lanka. Cyclone Fani became the worst tropical cyclone to strike the Indian state of Odisha since 1999.
April 30 – An EF3 wedge tornado in Oklahoma kills two people and injured nine others.
May
May 4–11 – Cyclone Lili caused damage Eastern Indonesia, East Timor, and Top End.
May 17–30 – A 14-day long tornado outbreak sequence in the United States kills 14 people (8 tornadic and 6 non-tornadic) and injured 288 others from 392 tornadoes.
May 27 – An EF4 tornado during the tornado outbreak sequence of May 2019 killed one person indirectly and injured 166 others. The National Weather Service issued a particularly dangerous situation and tornado emergency for the tornado as it entered Dayton, Ohio.
May 18 – June 14 – The Arkansas River Flood of 2019 kills five people and caused $3 billion (2019 USD) in damage across Arkansas and Oklahoma.
May 31 – An F2 tornado in Chile kills one person and injured 23 others.
June
June 8–15 – The Sand Fire of 2019 injured two people and burned 2,512 acres in California.
June 10–18 – Cyclone Vayu kills eight people and caused $140,000 (2019 USD) in damage across Maldives, India, Pakistan, and Oman.
July
July 3 – An EF4 Stovepipe tornado in China kills six people and injured 190 others.
July 11–19 – Hurricane Barry kills two people and caused $600 million (2019 USD) in damage across the United States and Canada. Hurricane Barry was the wettest tropical cyclone on record in Arkansas and the fourth-wettest in Louisiana.
July 14 – With a low of , Miami set a record for their warmest night on record.
July 14–21 – Tropical Storm Danas kills six people and caused $6.4 million (2019 USD) in damage across the Philippines, Taiwan, Japan, and South Korea.
July 28 – A F2 tornado in Italy kills one person. This tornado was part of a small 11 tornado outbreak in Europe.
July 30 – August 4 – Tropical Storm Wipha kills 27 people and caused $76.8 million (2019 USD) in damage across South China, Vietnam, and Laos.
July (31)–August (8) – Floods in Vadodara killed 8 people.
August
August 1–11 – Typhoon Francisco kills two people and caused damage across Japan, Korean Peninsula, and Russia's Far East.
August 1–29 – Floods in Karnataka, India kills 61 people with 15 missing and caused $4.95 billion (2019 USD) in damage.
August 2–14 – Typhoon Lekima, also known as Typhoon Hanna, kills 105 people and caused $9.28 billion (2019 USD) in damage across the Caroline Islands, East China, the Philippines, the Ryukyu Islands, Taiwan, and Malaysia. Typhoon Lekima was the second-costliest typhoon in Chinese history.
August 8–29 – Severe Floods in Kerala, India kills 121 people.
August 24 – September 7: Hurricane Dorian kills 84 people with 245 missing and caused $5.1 billion (2019 USD) in damage across the Lesser Antilles, Puerto Rico, The Bahamas (especially the Abaco Islands and Grand Bahama), the Eastern United States (especially Florida, Georgia, South Carolina, and North Carolina), and Eastern Canada. Hurricane Dorian became the strongest hurricane on record to hit The Bahamas.
August 29 – An EF2 tornado in China kills eight people and injured two others.
August 29 – September 12 – Typhoon Faxai, known in Japan as Reiwa 1 Bōsō Peninsula Typhoon, kills three people and caused $10 billion (2019 USD) in damage across Wake Island and Japan.
August 31 – September 8 – Typhoon Lingling kills eight people and caused $236 million (2019 USD) in damage across the Philippines, Taiwan, China, Japan, South Korea, North Korea, and Russia.
September
September 3–5 – Tropical Storm Fernand kills one person and caused $11.3 million (2019 USD) in damage across Northern Mexico and South Texas.
September 13–20 – Hurricane Humberto kills two people and caused over $25 million (2019 USD) in damage across the Bahamas, the East Coast of the United States, Puerto Rico, Bermuda, and Atlantic Canada.
September 17–19 – Tropical Storm Imelda kills seven people and caused $5 billion (2019 USD) in damage across Texas, Louisiana, Oklahoma, and Arkansas. Tropical Storm Imelda was the fourth-wettest tropical cyclone on record in the U.S. state of Texas.
September 22–27 – Tropical Storm Karen caused $3.53 million (2019 USD) in damage across the Windward Islands, Trinidad and Tobago, Venezuela, the US Virgin Islands, the British Virgin Islands, and Puerto Rico.
September 23 – October 7 – Hurricane Lorenzo, also known as Storm Lorenzo, kills 20 people and caused $367 million (2019 USD) in damage across West Africa, Cape Verde, the Lesser Antilles, the Eastern United States, Azores, the British Isles, France, Germany, and Eastern Europe. Hurricane Lorenzo was the easternmost Category 5 Atlantic hurricane on record.
September 25–28 – The 2019 Pune Flood kills 22 people and caused damage across Pune, India.
September 27 – October 5 – Typhoon Mitag, also known as Typhoon Onyok, kills 17 people and caused $816 million (2019 USD) in damage across the Philippines, the Ryukyu Islands, Taiwan, East China (particularly Zhoushan), and South Korea.
September 29 – October 1 – Tropical Storm Narda kills six people and caused $15.2 million (2019 USD) in damage across Western Mexico, the Baja California Peninsula, and the Southwestern United States.
October
October 1–3 – A rare, record breaking October heatwave hits the Eastern US. Some places, like Tuscaloosa, Alabama and Meridian, Mississippi, soar above for the first time in October. Several other locations in the Southeast tied or set monthly record highs on 3 consecutive days. Alabama, Florida, Mississippi, Delaware, Tennessee, Maryland and Washington DC break their monthly record high for October, which was also tied in New Jersey, New York and Kentucky. The hottest state was Alabama, which hit . The Northeast's cooldown was more abrupt then the Southeast, as by October 3, temperatures in LaGuardia Airport dropped from (where the state monthly high was tied), down to . Raleigh saw their hottest temperature of the year and their latest in season temperatures above .
October 4–22 – Typhoon Hagibis, known in Japan as Reiwa 1 East Japan Typhoon, kills 98 people with 7 missing and caused $15 billion (2019 USD) in damage across the Mariana Islands, Japan, Russia, Alaska. Typhoon Hagibis became the costliest Pacific typhoon in recorded history (when unadjusted for inflation), the strongest typhoon to strike mainland Japan in decades, the deadliest typhoon to strike Japan since 1979, and one of the largest typhoons ever recorded, with a peak gale-force diameter of 825 nautical miles.
October 18–21 – Tropical Storm Nestor kills three people and caused $150 million (2019 USD) in damage across Central America, the Yucatan Peninsula, and the Southeastern United States.
October 20–22 – A tornado outbreak in the South Central and Southeastern United States caused $2 billion (2019 USD) in damage from 36 tornadoes.
October 20 – An EF 3 tornado in Texas during the Tornado outbreak of October 20–22 caused $1.55 billion (2019 USD) in damage across its 15.76 mi (25.36 km) path, making this the costliest tornado event in Texas history.
October 25–26 – According to Japan Meteorological Agency official confirmed report, a heavy massive rain, following flash flood hit in around Boso Peninsula, Chiba Prefecture, Japan, A Fire and Disaster Management Agency official confirmed report, 13 persons died and 13 persons were injured,
October 25–27 – Tropical Storm Olga kills two people and caused $400 million (2019 USD) in damage across the Central United States and the Great Lakes region.
October 25–29 – Hurricane Pablo caused damage across the British Isles, Portugal (Azores, Madeira), and France and became the farthest east-forming hurricane in the North Atlantic tropical cyclone basin on record.
October 28 – November 11 – Tropical Storm Matmo and Cyclone Bulbul kill 43 people and caused a combined damage total of $3.54 billion (2019 USD) across Vietnam, Laos, Cambodia, Thailand, Myanmar, the Andaman and Nicobar Islands, Eastern India, and Bangladesh. Cyclone Bulbul is only the second storm to make landfall on Bangladesh as a Category 1 hurricane-equivalent cyclone, the first being another Cyclone in October 1960.
November
November 4–11 – Typhoon Nakri kills six people and caused $35.6 million (2019 USD) in damage across the Philippines and Vietnam.
November 12 – A tornado in South Africa kills two people and injured several more.
November 24 – December 6 – Typhoon Kammuri, known in the Philippines as Typhoon Tisoy, kills 17 people and caused $116 million (2019 USD) in damage across the Caroline Islands, the Mariana Islands, and the Philippines.
November 26–27 An EF2 tornado in Louisiana kills one person.
November 26 – December 3 – A winter storm causes 8 deaths.
December
December 2–14 – Cyclone Belna kills nine people and caused over $25 million (2019 USD) in damage across Seychelles, Mayotte, Comoros, and Madagascar.
December 16–17 – A tornado outbreak across Louisiana, Mississippi, Alabama, Tennessee, Florida, and Georgia kills four people (3 tornadic and 1 non-tornadic) and injured more than 14 others from 40 tornadoes.
December 18 - During an extreme heatwave, Australia recorded its hottest ever day, with the national average temperature reaching . This broke the record set only a day prior, when the average temperature reached .
December 19–29 – Typhoon Phanfone, known in the Philippines as Typhoon Ursula kills 50 people with 55 missing and caused $67.2 million (2019 USD) in damage across the Caroline Islands and the Philippines.
December 19 – A snow squall on Interstate 80 in Pennsylvania caused 2 deaths. The same snow squall forced Interstate 390 to close as well.
December 23, 2019 – January 2, 2020 – Cyclone Sarai kills two people and caused $2.3 million (2019 USD) in damage across Tuvalu, Vanuatu, Fiji, Tonga, Niue, and the Cook Islands.
See also
Weather of 2020
References
Weather by year
2019 meteorology
2019-related lists | Weather of 2019 | Physics | 4,691 |
42,719,380 | https://en.wikipedia.org/wiki/William%20D.M.%20Paton | Sir William Drummond Macdonald Paton CBE FRS (5 May 1917 – 17 October 1993) was a British pharmacologist and vivisection activist.
Biography
Paton was born in Hendon and educated at Repton School and New College, Oxford, where he was awarded a BA in animal physiology. In 1939 he entered University College Hospital (UCH) to study clinical medicine and was appointed house physician to the medical unit.
Unfit for military service he took the post of pathologist in a tuberculosis sanatorium, later moving to the National Institute for Medical Research, then in Hampstead, London. He worked at NIMR for 8 years on the pharmacology of acetylcholine and its benefits in the control of hypertension. For this work he and his colleague Eleanor Zaimis were amongst the recipients of the first Gairdner Foundation International Awards in 1959.
In 1952 he returned to UCH as reader in applied pharmacology, and spent the next two years studying submarine physiology, developing the blend of oxygen, helium and nitrogen (Tri-mix) which enables divers to work at deeper depths. In 1956, he was awarded the Cameron Prize for Therapeutics of the University of Edinburgh.
In 1954 he was appointed Professor of Pharmacology at the Royal College of Surgeons, remaining there until 1959, when he was given the post of Professor of Pharmacology at Oxford University and made a Fellow of Balliol College. He was appointed a CBE in 1968 and knighted in 1979. He retired in 1984.
He died in Oxford, aged 76.
Fellow of the Royal Society
He was elected a Fellow of the Royal Society in 1956. His nomination citation read: " Distinguished for his researches on histamine and methonium compounds. With MacIntosh he showed that many simple organic bases are histamine releasers and, later, he found that this property is shared by opium alkaloids and by a phenylethylamine derivative, compound 48/80, the most active known releaser. One of the outstanding recent contributions to pharmacology and therapeutics is his discovery, with Zaimis, of the actions of the methonium compounds - decamethonium a potent neuromuscular, and hexamethonium a potent ganglion blocking substance. His analysis of their mode of action has since become the model for such studies and led to the distinction between block by depolarisation and competition. Hexamethonium became the first effective drug in the treatment of malignant hypertension and of great value in cranial and plastic surgery. During the war he worked for the Royal Naval Personnel Research Committee on submarine physiology. "
Views on animals
Paton was a vivisection activist and an opponent of animal rights. His 1984 book Man and Mouse: Animals in Medical Research was a defence of the use of animals in medical research. It was revised in 1993. According to Paton, a distinction should be made between moral agents and moral objects. Humans are moral agents who can accept duties and claim rights whilst animals are moral objects who have no duties, cannot make claims and do not have rights.
Selected publications
Vivisection, Morals, Medicine: Commentary from a Vivisecting Professor of Pharmacology (1983)
Man and Mouse: Animals in Medical Research (1984, 1993)
References
1917 births
1993 deaths
Alumni of New College, Oxford
British pharmacologists
Commanders of the Order of the British Empire
Critics of animal rights
Fellows of Balliol College, Oxford
Fellows of the Royal Society
Knights Bachelor
People educated at Repton School
People from Hendon
Vivisection activists | William D.M. Paton | Chemistry | 733 |
1,994,795 | https://en.wikipedia.org/wiki/Scale%20height | In atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter H, is a distance (vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approximately 2.718).
Scale height used in a simple atmospheric pressure model
For planetary atmospheres, scale height is the increase in altitude for which the atmospheric pressure decreases by a factor of e. The scale height remains constant for a particular temperature. It can be calculated by
or equivalently,
where
kB = Boltzmann constant =
R = molar gas constant = 8.314 J⋅K−1⋅mol−1
T = mean atmospheric temperature in kelvins = 250 K for Earth
m = mean mass of a molecule
M = mean molar mass of atmospheric particles = 0.029 kg/mol for Earth
g = acceleration due to gravity at the current location
The pressure (force per unit area) at a given altitude is a result of the weight of the overlying atmosphere. If at a height of z the atmosphere has density ρ and pressure P, then moving upwards an infinitesimally small height dz will decrease the pressure by amount dP, equal to the weight of a layer of atmosphere of thickness dz.
Thus:
where g is the acceleration due to gravity. For small dz it is possible to assume g to be constant; the minus sign indicates that as the height increases the pressure decreases. Therefore, using the equation of state for an ideal gas of mean molecular mass M at temperature T, the density can be expressed as
Combining these equations gives
which can then be incorporated with the equation for H given above to give
which will not change unless the temperature does. Integrating the above and assuming P0 is the pressure at height z = 0 (pressure at sea level), the pressure at height z can be written as
This translates as the pressure decreasing exponentially with height.
In Earth's atmosphere, the pressure at sea level P0 averages about , the mean molecular mass of dry air is , and hence m = × = . As a function of temperature, the scale height of Earth's atmosphere is therefore H/T = k/mg = / ( × ) = . This yields the following scale heights for representative air temperatures:
T = 290 K, H = 8500 m,
T = 273 K, H = 8000 m,
T = 260 K, H = 7610 m,
T = 210 K, H = 6000 m.
These figures should be compared with the temperature and density of Earth's atmosphere plotted at NRLMSISE-00, which shows the air density dropping from 1200 g/m3 at sea level to 0.125 g/m3 at 70 km, a factor of 9600, indicating an average scale height of 70 / ln(9600) = 7.64 km, consistent with the indicated average air temperature over that range of close to 260 K.
Note:
Density is related to pressure by the ideal gas laws. Therefore, density will also decrease exponentially with height from a sea-level value of ρ0 roughly equal to .
At an altitude over 100 km, the atmosphere is no longer well-mixed, and each chemical species has its own scale height.
Here temperature and gravitational acceleration were assumed to be constant, but both may vary over large distances.
Planetary examples
Approximate atmospheric scale heights for selected Solar System bodies:
Venus: 15.9 km
Earth: 8.5 km
Mars: 11.1 km
Jupiter: 27 km
Saturn: 59.5 km
Titan: 21 km
Uranus: 27.7 km
Neptune: 19.1–20.3 km
Pluto: ~50 km
Scale height for a thin disk
For a disk of gas around a condensed central object, such as, for example, a protostar, one can derive a disk scale height which is somewhat analogous to the planetary scale height. We start with a disc of gas that has a mass small relative to the central object. We assume that the disc is in hydrostatic equilibrium with the z component of gravity from the star, where the gravity component is pointing to the midplane of the disk:
where
G = Gravitational constant ≈
r = the radial cylindrical coordinate for the distance from the center of the star or centrally condensed object
z = the height/altitude cylindrical coordinate for the distance from the disk midplane (or center of the star)
M* = the mass of the star/centrally condensed object
P = the pressure of the gas in the disk
= the gas mass density in the disk
In the thin disk approximation, , and the hydrostatic equilibrium, the equation is
To determine the gas pressure, one can use the ideal gas law:
with
T = the gas temperature in the disk, where the temperature is a function of r, but independent of z
= the mean molecular mass of the gas
Using the ideal gas law and the hydrostatic equilibrium equation, gives
which has the solution
where is the gas mass density at the midplane of the disk at a distance r from the center of the star, and is the disk scale height with
with the solar mass, the astronomical unit, and the atomic mass unit.
As an illustrative approximation, if we ignore the radial variation in the temperature , we see that and that the disk increases in altitude as one moves radially away from the central object.
Due to the assumption that the gas temperature T in the disk is independent of z, is sometimes known as the isothermal disk scale height.
Disk scale height in a magnetic field
A magnetic field in a thin gas disk around a central object can change the scale height of the disk. For example, if a non-perfectly conducting disk is rotating through a poloidal magnetic field (i.e., the initial magnetic field is perpendicular to the plane of the disk), then a toroidal (i.e., parallel to the disk plane) magnetic field will be produced within the disk, which will pinch and compress the disk. In this case, the gas density of the disk is
where the cut-off density has the form
where
is the permeability of free space
is the electrical conductivity of the disk
is the magnetic flux density of the poloidal field in the direction
is the rotational angular velocity of the central object (if the poloidal magnetic field is independent of the central object, then can be set to zero)
is the keplerian angular velocity of the disk at a distance from the central object.
These formulae give the maximum height of the magnetized disk as
while the e-folding magnetic scale height is
See also
Time constant
References
Atmospheric dynamics
Vertical position | Scale height | Physics,Chemistry | 1,339 |
23,582,523 | https://en.wikipedia.org/wiki/C8H7N | {{DISPLAYTITLE:C8H7N}}
The molecular formula C8H7N (molar mass: 117.15 g/mol, exact mass: 117.0578 u) may refer to:
Benzyl cyanide (BnCN)
Indole
Indolizine
Isoindole
Molecular formulas | C8H7N | Physics,Chemistry | 70 |
77,925,722 | https://en.wikipedia.org/wiki/Fluorothiazinone | Fluorothiazinone (CL-55, Ftortiazinon, Фтортиазинон) is an antibiotic drug, first developed in Russia in 2010 and active against various species of Gram-negative bacteria through inhibition of the type III secretion system (T3SS). It has seen limited clinical use in Russia and is in clinical trials which may eventually see it accepted for use more widely.
See also
List of Russian drugs
Aurodox
Triazavirin
References
Amides
Antibiotics
Catechols
Ethoxy compounds
Experimental drugs
Fluorobenzene derivatives
Russian drugs
Thiadiazines | Fluorothiazinone | Chemistry,Biology | 132 |
24,423,666 | https://en.wikipedia.org/wiki/C16H14O4 | {{DISPLAYTITLE:C16H14O4}}
The molecular formula C16H14O4 (molar mss : 270.28 g/mol, exact mass : 270.089209 u) may refer to:
Alpinetin, a flavanone
Cardamomin, a chalcone
Imperatorin, a coumarin
Medicarpin, a flavonoid
Nudol, a phenanthrenoid
Molecular formulas | C16H14O4 | Physics,Chemistry | 102 |
2,733,403 | https://en.wikipedia.org/wiki/Polytomy | An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree that contains any multifurcations can be described as a multifurcating tree.
Soft polytomies vs. hard polytomies
Two types of polytomies are recognized, soft and hard polytomies.
Soft polytomies are the result of insufficient phylogenetic information: though the lineages diverged at different times – meaning that some of these lineages are closer relatives than others, and the available data does not allow recognition of this. Most polytomies are soft, meaning that they would be resolved into a typical tree of dichotomies if better data were available.
In contrast, a hard polytomy represents a true divergence event of three or more lineages.
Applications
Interpretations for a polytomy depend on the individuals that are represented in the phylogenetic tree.
Species polytomies
If the lineages in the phylogenetic tree stand for species, a polytomy shows the simultaneous speciation of three or more species. In particular situations, they may be common, for example when a species that has rapidly expanded its range or is highly panmictic undergoes peripatric speciation in different regions.
An example is the Drosophila simulans species complex. Here, the ancestor seems to have colonized two islands at the same time but independently, yielding two equally old but divergently evolved daughter species
Molecular polytomies
If a phylogenetic tree is reconstructed from DNA sequence data of a particular gene, a hard polytomy arises when three or more sampled genes trace their ancestry to a single gene in an ancestral organism. In contrast, a soft polytomy stems from branches on gene trees of finite temporal duration but for which no substitutions have occurred.
Recognizing hard polytomies
As DNA sequence evolution is usually much faster than evolution of complex phenotypic traits, it may be that genetic lineages diverge a short time apart from each other, while the actual organism has not changed if the whole ancestral population is considered. Since few if any individuals in a population are genetically alike in any one population – especially if lineage sorting has not widely progressed – it may be that hard polytomies are indeed rare or nonexistent if the entire genome of each individual organism is considered, but rather widespread on the population genetical level if entire species are considered as interbreeding populations (see also species concept).
"Speciation or lineage divergence events occurring at the same time" refers to evolutionary time measured in generations, as this is the only means that novel traits (e.g. germline point mutations) can be passed on. In practical terms, the ability to distinguish between hard and soft polytomies is limited: if for example a kilobase of DNA sequences that mutate approximately 1% per million years is analyzed, lineages diverging from the same ancestor within the same 100,000 years cannot be reliably distinguished as to which one diverged first.
Founder effects and genetic drift may result in different rates of evolution. This can easily confound molecular clock algorithms to the point where hard polytomies become unrecognizable as such.
See also
Cladistics
Computational phylogenetics
Phylogenetic comparative methods
Phylogenetics
Systematics
References
External links
http://biology.fullerton.edu/biol404/phylo/polytomies.html
Phylogenetics | Polytomy | Biology | 735 |
75,136,880 | https://en.wikipedia.org/wiki/Aleutite | Aleutite is both a vanadate and arsenate mineral but it can also be considered as a natural salt-inclusion phase that was first discovered at Second scoria cone of the Great Fissure Tolbachik eruption in the summer of 2015 in Kamchatka, Russia. Aleutite is a fumarolic mineral found with many other newly discovered minerals at this location. It gained the name from the Aleuts, the ethnic group who are the original inhabitants living on the Commander Islands, Aleutsky District, Kamchatka Krai. This mineral is very brittle and has a dark red color. Aleutite is a new structure type, the structure was refined as a 2-component twin, the twin ratio equals (0.955:0.045).
Occurrence
Aleutite occurs as a product of fumarolic activity. It was found in the summer of 2015 in Yadovitaya fumarole at the Second Scoria Cone of the Northern Breakthrough of the Great Fissure Tolbachik Eruption in Kamchatka, Russia. The Second Scoria Cone is located approximately 18 km SSW of the active shield volcano Ploskiy Tolbachik. The temperature of gases at the sampling location was about 300 °C. Aleutite could be deposited directly from the gas phase as a volcanic sublimate. All the recovered samples were immediately packed and isolated to avoid any contact with atmosphere. Aleutite is very rare and closely associates with anhydrite. Other associated minerals are euchlorine, kamchatkite, langbeinite, lyonsite, pseudolyonsite, tenorite, hematite.
Physical properties
Aleutite occurs as individual crystals in the masses of polycrystalline anhydrite. Aleutite is dark red, with reddish black streak, and has an adamantine luster. It is brittle with no visible cleavage observed. Parting was not observed, and its fracture is uneven. The density could not be measured due to lack of sufficient material. The calculated specific gravity is 4.887 g/cm3.
Optical properties
The measured optical properties of Aleutite were found through reflected light. The mineral had high values of refractive indices which is typical of arsenates and vanadates. Reflectance measurements were made using a SiC standard in air which ranged from 400–700 nm. Aleutite is grey with yellowish tint in reflected light, it is non-pleochroic with abundant brown-red internal reflections and a weak bireflectance.
Chemical properties
Aleutite is both a vanadate and arsenate that may can compared to averievite which has had a formula of Cu6(VO4)2O2Cl2. It may also be comparable with piypite with a formula of K2Cu2O(SO4)2. The empirical formula of Aleutite cab be calculated on the basis of (As+V+Mo+Fe3+) = 2 apfu is Сu5.40Zn0.05Ca0.01As1.09V0.84Mo0.04Fe0.03K0.05Pb0.02Rb0.01Cs0.01O9.97Cl1.07 or (Сu4.94Zn0.05Ca0.01)Σ5.00O2.11[(As2.11V0.42Mo0.02Fe0.02)Σ1.00OΣ3.93]2 ∙ (Cu0.46K0.05Pb0.02Rb0.01Cs0.01)Σ0.55Cl1.07. Taking into account structural data, the simplified formula is [Cu5O2](AsO4)(VO4)·(Cu0.5□0.5)Cl. Aleutite is soluble in hot H2O.
Chemical composition
X-ray crystallography
Aleutite is in the monoclinic crystal system and has a space group of C2/m. Its unit cell dimensions are as follows: a = 18.0788(9) Å, b = 6.2270(5) Å, c = 8.2445(3) Å, β = 90.56(4)º, V = 928.09(7) Å3, Z = 4. Aleutite has a point group of 2/m. The [Cu5O2]6+ band in aleutite can be considered part of a kagome network.
See also
List of Minerals
References
Natural materials
Monoclinic minerals
Minerals in space group 21
Wikipedia Student Program
Arsenate minerals
Vanadate minerals
Chloride minerals
Copper minerals | Aleutite | Physics | 982 |
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