id int64 580 79M | url stringlengths 31 175 | text stringlengths 9 245k | source stringlengths 1 109 | categories stringclasses 160
values | token_count int64 3 51.8k |
|---|---|---|---|---|---|
870,586 | https://en.wikipedia.org/wiki/Acetamide | Acetamide (systematic name: ethanamide) is an organic compound with the formula CH3CONH2. It is an amide derived from ammonia and acetic acid. It finds some use as a plasticizer and as an industrial solvent. The related compound N,N-dimethylacetamide (DMA) is more widely used, but it is not prepared from acetamide. Acetamide can be considered an intermediate between acetone, which has two methyl (CH3) groups either side of the carbonyl (CO), and urea which has two amide (NH2) groups in those locations. Acetamide is also a naturally occurring mineral with the IMA symbol: Ace.
Production
Laboratory scale
Acetamide can be produced in the laboratory from ammonium acetate by dehydration:
[NH4][CH3CO2] → CH3C(O)NH2 + H2O
Alternatively acetamide can be obtained in excellent yield via ammonolysis of acetylacetone under conditions commonly used in reductive amination.
It can also be made from anhydrous acetic acid, acetonitrile and very well dried hydrogen chloride gas, using an ice bath, alongside more valuable reagent acetyl chloride. Yield is typically low (up to 35%), and the acetamide made this way is generated as a salt with HCl.
Industrial scale
In a similar fashion to some laboratory methods, acetamide is produced by dehydrating ammonium acetate or via the hydration of acetonitrile, a byproduct of the production of acrylonitrile:
CH3CN + H2O → CH3C(O)NH2
Uses
Acetamide is used as a plasticizer and an industrial solvent. Molten acetamide is good solvent with a broad range of applicability. Notably, its dielectric constant is higher than most organic solvents, allowing it to dissolve inorganic compounds with solubilities closely analogous to that of water. Acetamide has uses in electrochemistry and the organic synthesis of pharmaceuticals, pesticides, and antioxidants for plastics. It is a precursor to thioacetamide.
Occurrence
Acetamide has been detected near the center of the Milky Way galaxy. This finding is potentially significant because acetamide has an amide bond, similar to the essential bond between amino acids in proteins. This finding lends support to the theory that organic molecules that can lead to life (as we know it on Earth) can form in space.
On 30 July 2015, scientists reported that upon the first touchdown of the Philae lander on comet 67/P surface, measurements by the COSAC and Ptolemy instruments revealed sixteen organic compounds, four of which – acetamide, acetone, methyl isocyanate, and propionaldehyde – were seen for the first time on a comet.
In addition, acetamide is found infrequently on burning coal dumps, as a mineral of the same name.
References
External links
Hazardous air pollutants
IARC Group 2B carcinogens
Plasticizers
Organic minerals | Acetamide | Chemistry | 659 |
2,137,248 | https://en.wikipedia.org/wiki/Starsem | Starsem is a French-Russian company that was created in 1996 to commercialise the Soyuz launcher internationally. Starsem is headquartered in Évry, France (near Paris) and has the following shareholders:
ArianeGroup (35%)
Arianespace (15%)
Roscosmos (25%)
Progress Rocket Space Centre (25%)
References
External links
Starsem, the Soyuz company website
Commercial launch service providers
Space industry companies of Russia | Starsem | Astronomy | 91 |
5,125,879 | https://en.wikipedia.org/wiki/Jeffries%20Wyman | Jeffries Wyman (August 11, 1814 – September 4, 1874) was an American anatomist, curator, and professor. He was the first curator of the Peabody Museum of Archaeology and Ethnology and taught anatomy at Harvard Medical School from 1847 to 1874.
Early life
Wyman was born in Chelmsford, Massachusetts in 1814. His father, Rufus Wyman, was the first director of the McLean Asylum.
Wyman attended Phillips Exeter Academy. He graduated Harvard College in 1833 and Harvard Medical School in 1837.
Career
He was made curator at Lowell Institute, Boston, in 1839 and remained affiliated there until 1842. Fees from Lowell Institute lectures enabled him to study in Europe, from 1841 to 1842, where he learned from anatomist Richard Owen in London. In addition to studying with Owen, Wyman also attended lectures by Achille Valenciennes, Isidore Geoffroy Saint-Hilaire, Marie Jean Pierre Flourens, and Etienne Serres in Paris.
Upon his return to the United States, Wyman hoped to gain a professorship at Harvard College but the position went to Asa Gray. In 1843, he was elected professor of anatomy and physiology at Hampden-Sydney College in Richmond, Virginia. In a series of letters written between 1843 and 1848 to his Boston friend and fellow medical doctor, David Humphreys Storer, Wyman revealed his unhappiness with the quality of the school, the treatment of the professors, and life in the South. He wrote, "As soon as circumstances will permit I shall make my way back to the glorious city of Boston, the like of which exists not on the face of the earth."
In 1847, Wyman became Hersey Professor of Anatomy at Harvard College, where he remained until his death. He was also the first curator of the Peabody Museum of Archaeology and Ethnology, holding that position until 1866. He made extensive and valuable collections in comparative anatomy and archæology and published nearly seventy scientific papers. With American physician and missionary Thomas Staughton Savage, he was the first to scientifically describe the gorilla.
Although he did not achieve the fame of some of his contemporaries, he was respected by his peers: "In his special branches his authority was recognized the world over." In 1866, he was elected as a member of the American Philosophical Society. Wyman was elected a member of the American Antiquarian Society in 1868. He was the president of the American Association for the Advancement of Science in 1858.
After Wyman's death, his former student Burt G. Wilder eulogized him as "regarded by all as the highest anatomical authority in America, and the compeer of Owen, Huxley, and Gegenbauer in the Old World."
Parkman–Webster murder case
In 1850, Wyman was called to testify for the prosecution in the Parkman–Webster murder case, where Dr. John White Webster was on trial for the murder of Dr. George Parkman. Wyman's recognized authority as a comparative anatomist caused the coroner, Jabez Pratt, to call upon him to examine and testify about bones found in a furnace in November 1849. He cataloged them and noted that the fragments belonged to a single body; his testimony regarding the jawbone contributed to the belief that the bones belonged to Parkman. Wyman also testified about the alleged bloodstains found on pantaloons and slippers belonging to Webster.
Parkman's gaunt figure was known on the streets of Boston. A sketch of Dr. Parkman as he was last seen was published in the New York Globe's account of the trial. While the bones could not be definitively identified as Dr. Parkman, Wyman contributed to the belief that they were Parkman's by providing the court with a "diagram, exhibiting the position in the skeleton, of the bones found and showing, (in some degree,) what would be necessary to complete the body." This rendering was remarkably similar to the sketch of Parkman striding and was labeled "Restoration of Dr. Parkman's Skeleton," no doubt influencing the jury.
Coincidentally, Wyman's brother, Dr. Morrill Wyman, and his wife, had spent the evening of Parkman's disappearance with Webster and his wife at the home of Harvard professor Daniel Treadwell.
Views on evolution
Wyman was a theist who attended the Unitarian Church at Harvard and, as such, leaned toward a belief in a "theistic, morphological form of evolution rather than natural selection." Two science historians who chronicled Wyman's career, A. Hunter Dupree and Toby Appel, disagreed as to Wyman's reception of Charles Darwin's theories of evolution and natural selection. Dupree believed that Wyman's religious beliefs caused him to struggle with Darwin's theories, accepting them "only by intense effort both as a scientist and a person."
Appel believed that Wyman had no difficulty accepting Darwin's theory of evolution but that his work in philosophical anatomy made it "doubtful that he ever accepted natural selection." Appel made a case for Wyman as a proponent of philosophical anatomy at Harvard, along with his colleagues Louis Agassiz and Asa Gray. Philosophical anatomy, also known as transcendental anatomy, was the "search for ideal patterns of structure in nature." This search did not prevent Wyman and Gray from accepting evolution, although Agassiz never did. However, unlike Gray, Wyman could not accept natural selection as the method of evolution, believing instead in evolution as "directed by the Creator."
When Darwin's On the Origin of Species was published in 1859, Wyman's one-time mentor, Richard Owen came out against the book, while his colleague Asa Gray supported it. In 1860, Darwin went to Gray to enlist Wyman's support, due to Wyman's work on higher apes and anatomy. Wyman wrote to Darwin agreeing that "progressive development is a far more probable theory than progressive creations". The two men corresponded between 1860 and 1866, with Darwin writing at one point, "I know hardly anyone whose opinions I should be more inclined to defer to."
Personal life
Wyman married Adeline Wheelwright in 1850. They had two daughters, Mary and Susan, before Adeline died in 1855. In 1861, he married Annie Williams Whitney, with whom he had a son, Jeffries Wyman Jr. Whitney died in 1864, the year of their son's birth.
Wyman died in Bethlehem, New Hampshire of a pulmonary hemorrhage on September 4, 1874. In 1978, the Peabody Museum published Dear Jeffie, a collection of letters and sketches that Wyman had written to his son from 1866 to 1874 when he was doing fieldwork in the states and abroad.
His brother Morrill Wyman was a respected Cambridge doctor. His grandson, also named Jeffries Wyman (1901–1995), was a molecular biologist, biophysicist, and professor at Harvard.
Selected publications
Wyman, Jeffries; "Chapter VII - Observations upon the Mammalian Remains of Extinct and Existing Species found in the Crevices of the Lead-bearing Rock, and in the Superficial Accumulations within the Lead Region of Wisconsin and Iowa" in Geological Survey of State of Wisconsin, vol. 1, 1862.
Wyman, Jeffries; “Fossil Mammels” - “The U.S. Naval Astronomical Expedition to the Southern Hemisphere During the Years 1849-‘50-‘51-‘52: Volume II.”
References
External links
Jeffries Wyman Papers, Harvard Medical Library
1814 births
1874 deaths
People from Chelmsford, Massachusetts
Phillips Exeter Academy alumni
Harvard College alumni
Harvard Medical School alumni
Hampden–Sydney College faculty
American science writers
Deaths from pulmonary hemorrhage
Theistic evolutionists
American Unitarians
19th-century American physicians | Jeffries Wyman | Biology | 1,607 |
172,088 | https://en.wikipedia.org/wiki/Machine%20vision | Machine vision is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to many technologies, software and hardware products, integrated systems, actions, methods and expertise. Machine vision as a systems engineering discipline can be considered distinct from computer vision, a form of computer science. It attempts to integrate existing technologies in new ways and apply them to solve real world problems. The term is the prevalent one for these functions in industrial automation environments but is also used for these functions in other environment vehicle guidance.
The overall machine vision process includes planning the details of the requirements and project, and then creating a solution. During run-time, the process starts with imaging, followed by automated analysis of the image and extraction of the required information.
Definition
Definitions of the term "Machine vision" vary, but all include the technology and methods used to extract information from an image on an automated basis, as opposed to image processing, where the output is another image. The information extracted can be a simple good-part/bad-part signal, or more a complex set of data such as the identity, position and orientation of each object in an image. The information can be used for such applications as automatic inspection and robot and process guidance in industry, for security monitoring and vehicle guidance. This field encompasses a large number of technologies, software and hardware products, integrated systems, actions, methods and expertise. Machine vision is practically the only term used for these functions in industrial automation applications; the term is less universal for these functions in other environments such as security and vehicle guidance. Machine vision as a systems engineering discipline can be considered distinct from computer vision, a form of basic computer science; machine vision attempts to integrate existing technologies in new ways and apply them to solve real world problems in a way that meets the requirements of industrial automation and similar application areas. The term is also used in a broader sense by trade shows and trade groups such as the Automated Imaging Association and the European Machine Vision Association. This broader definition also encompasses products and applications most often associated with image processing. The primary uses for machine vision are automatic inspection and industrial robot/process guidance. In more recent times the terms computer vision and machine vision have converged to a greater degree. See glossary of machine vision.
Imaging based automatic inspection and sorting
The primary uses for machine vision are imaging-based automatic inspection and sorting and robot guidance.; in this section the former is abbreviated as "automatic inspection". The overall process includes planning the details of the requirements and project, and then creating a solution. This section describes the technical process that occurs during the operation of the solution.
Methods and sequence of operation
The first step in the automatic inspection sequence of operation is acquisition of an image, typically using cameras, lenses, and lighting that has been designed to provide the differentiation required by subsequent processing. MV software packages and programs developed in them then employ various digital image processing techniques to extract the required information, and often make decisions (such as pass/fail) based on the extracted information.
Equipment
The components of an automatic inspection system usually include lighting, a camera or other imager, a processor, software, and output devices.
Imaging
The imaging device (e.g. camera) can either be separate from the main image processing unit or combined with it in which case the combination is generally called a smart camera or smart sensor. Inclusion of the full processing function into the same enclosure as the camera is often referred to as embedded processing. When separated, the connection may be made to specialized intermediate hardware, a custom processing appliance, or a frame grabber within a computer using either an analog or standardized digital interface (Camera Link, CoaXPress). MV implementations also use digital cameras capable of direct connections (without a framegrabber) to a computer via FireWire, USB or Gigabit Ethernet interfaces.
While conventional (2D visible light) imaging is most commonly used in MV, alternatives include multispectral imaging, hyperspectral imaging, imaging various infrared bands, line scan imaging, 3D imaging of surfaces and X-ray imaging. Key differentiations within MV 2D visible light imaging are monochromatic vs. color, frame rate, resolution, and whether or not the imaging process is simultaneous over the entire image, making it suitable for moving processes.
Though the vast majority of machine vision applications are solved using two-dimensional imaging, machine vision applications utilizing 3D imaging are a growing niche within the industry. The most commonly used method for 3D imaging is scanning based triangulation which utilizes motion of the product or image during the imaging process. A laser is projected onto the surfaces of an object. In machine vision this is accomplished with a scanning motion, either by moving the workpiece, or by moving the camera & laser imaging system. The line is viewed by a camera from a different angle; the deviation of the line represents shape variations. Lines from multiple scans are assembled into a depth map or point cloud. Stereoscopic vision is used in special cases involving unique features present in both views of a pair of cameras. Other 3D methods used for machine vision are time of flight and grid based. One method is grid array based systems using pseudorandom structured light system as employed by the Microsoft Kinect system circa 2012.
Image processing
After an image is acquired, it is processed. Central processing functions are generally done by a CPU, a GPU, a FPGA or a combination of these. Deep learning training and inference impose higher processing performance requirements. Multiple stages of processing are generally used in a sequence that ends up as a desired result. A typical sequence might start with tools such as filters which modify the image, followed by extraction of objects, then extraction (e.g. measurements, reading of codes) of data from those objects, followed by communicating that data, or comparing it against target values to create and communicate "pass/fail" results. Machine vision image processing methods include;
Stitching/Registration: Combining of adjacent 2D or 3D images.
Filtering (e.g. morphological filtering)
Thresholding: Thresholding starts with setting or determining a gray value that will be useful for the following steps. The value is then used to separate portions of the image, and sometimes to transform each portion of the image to simply black and white based on whether it is below or above that grayscale value.
Pixel counting: counts the number of light or dark pixels
Segmentation: Partitioning a digital image into multiple segments to simplify and/or change the representation of an image into something that is more meaningful and easier to analyze.
Edge detection: finding object edges
Color Analysis: Identify parts, products and items using color, assess quality from color, and isolate features using color.
Blob detection and extraction: inspecting an image for discrete blobs of connected pixels (e.g. a black hole in a grey object) as image landmarks.
Neural network / deep learning / machine learning processing: weighted and self-training multi-variable decision making Circa 2019 there is a large expansion of this, using deep learning and machine learning to significantly expand machine vision capabilities. The most common result of such processing is classification. Examples of classification are object identification,"pass fail" classification of identified objects and OCR.
Pattern recognition including template matching. Finding, matching, and/or counting specific patterns. This may include location of an object that may be rotated, partially hidden by another object, or varying in size.
Barcode, Data Matrix and "2D barcode" reading
Optical character recognition: automated reading of text such as serial numbers
Gauging/Metrology: measurement of object dimensions (e.g. in pixels, inches or millimeters)
Comparison against target values to determine a "pass or fail" or "go/no go" result. For example, with code or bar code verification, the read value is compared to the stored target value. For gauging, a measurement is compared against the proper value and tolerances. For verification of alpha-numberic codes, the OCR'd value is compared to the proper or target value. For inspection for blemishes, the measured size of the blemishes may be compared to the maximums allowed by quality standards.
Outputs
A common output from automatic inspection systems is pass/fail decisions. These decisions may in turn trigger mechanisms that reject failed items or sound an alarm. Other common outputs include object position and orientation information for robot guidance systems. Additionally, output types include numerical measurement data, data read from codes and characters, counts and classification of objects, displays of the process or results, stored images, alarms from automated space monitoring MV systems, and process control signals. This also includes user interfaces, interfaces for the integration of multi-component systems and automated data interchange.
Deep learning
The term deep learning has variable meanings, most of which can be applied to techniques used in machine vision for over 20 years. However the usage of the term in "machine vision" began in the later 2010s with the advent of the capability to successfully apply such techniques to entire images in the industrial machine vision space. Conventional machine vision usually requires the "physics" phase of a machine vision automatic inspection solution to create reliable simple differentiation of defects. An example of "simple" differentiation is that the defects are dark and the good parts of the product are light. A common reason why some applications were not doable was when it was impossible to achieve the "simple"; deep learning removes this requirement, in essence "seeing" the object more as a human does, making it now possible to accomplish those automatic applications. The system learns from a large amount of images during a training phase and then executes the inspection during run-time use which is called "inference".
Imaging based robot guidance
Machine vision commonly provides location and orientation information to a robot to allow the robot to properly grasp the product. This capability is also used to guide motion that is simpler than robots, such as a 1 or 2 axis motion controller. The overall process includes planning the details of the requirements and project, and then creating a solution. This section describes the technical process that occurs during the operation of the solution. Many of the process steps are the same as with automatic inspection except with a focus on providing position and orientation information as the result.
Market
As recently as 2006, one industry consultant reported that MV represented a $1.5 billion market in North America. However, the editor-in-chief of an MV trade magazine asserted that "machine vision is not an industry per se" but rather "the integration of technologies and products that provide services or applications that benefit true industries such as automotive or consumer goods manufacturing, agriculture, and defense."
See also
Machine vision glossary
Feature detection (computer vision)
Foreground detection
Vision processing unit
Optical sorting
References
Applications of computer vision
Computer vision | Machine vision | Engineering | 2,194 |
164,313 | https://en.wikipedia.org/wiki/Gravity%20wave | In fluid dynamics, gravity waves are waves in a fluid medium or at the interface between two media when the force of gravity or buoyancy tries to restore equilibrium. An example of such an interface is that between the atmosphere and the ocean, which gives rise to wind waves.
A gravity wave results when fluid is displaced from a position of equilibrium. The restoration of the fluid to equilibrium will produce a movement of the fluid back and forth, called a wave orbit. Gravity waves on an air–sea interface of the ocean are called surface gravity waves (a type of surface wave), while gravity waves that are the body of the water (such as between parts of different densities) are called internal waves. Wind-generated waves on the water surface are examples of gravity waves, as are tsunamis, ocean tides, and the wakes of surface vessels.
The period of wind-generated gravity waves on the free surface of the Earth's ponds, lakes, seas and oceans are predominantly between 0.3 and 30 seconds (corresponding to frequencies between 3 Hz and .03 Hz). Shorter waves are also affected by surface tension and are called gravity–capillary waves and (if hardly influenced by gravity) capillary waves. Alternatively, so-called infragravity waves, which are due to subharmonic nonlinear wave interaction with the wind waves, have periods longer than the accompanying wind-generated waves.
Atmosphere dynamics on Earth
In the Earth's atmosphere, gravity waves are a mechanism that produce the transfer of momentum from the troposphere to the stratosphere and mesosphere. Gravity waves are generated in the troposphere by frontal systems or by airflow over mountains. At first, waves propagate through the atmosphere without appreciable change in mean velocity. But as the waves reach more rarefied (thin) air at higher altitudes, their amplitude increases, and nonlinear effects cause the waves to break, transferring their momentum to the mean flow. This transfer of momentum is responsible for the forcing of the many large-scale dynamical features of the atmosphere. For example, this momentum transfer is partly responsible for the driving of the Quasi-Biennial Oscillation, and in the mesosphere, it is thought to be the major driving force of the Semi-Annual Oscillation. Thus, this process plays a key role in the dynamics of the middle atmosphere.
The effect of gravity waves in clouds can look like altostratus undulatus clouds, and are sometimes confused with them, but the formation mechanism is different. Atmospheric gravity waves reaching ionosphere are responsible for the generation of traveling ionospheric disturbances and could be observed by radars.
Quantitative description
Deep water
The phase velocity of a linear gravity wave with wavenumber is given by the formula
where g is the acceleration due to gravity. When surface tension is important, this is modified to
where σ is the surface tension coefficient and ρ is the density.
The gravity wave represents a perturbation around a stationary state, in which there is no velocity. Thus, the perturbation introduced to the system is described by a velocity field of infinitesimally small amplitude, Because the fluid is assumed incompressible, this velocity field has the streamfunction representation
where the subscripts indicate partial derivatives. In this derivation it suffices to work in two dimensions , where gravity points in the negative z-direction. Next, in an initially stationary incompressible fluid, there is no vorticity, and the fluid stays irrotational, hence In the streamfunction representation, Next, because of the translational invariance of the system in the x-direction, it is possible to make the ansatz
where k is a spatial wavenumber. Thus, the problem reduces to solving the equation
We work in a sea of infinite depth, so the boundary condition is at The undisturbed surface is at , and the disturbed or wavy surface is at where is small in magnitude. If no fluid is to leak out of the bottom, we must have the condition
Hence, on , where A and the wave speed c are constants to be determined from conditions at the interface.
The free-surface condition: At the free surface , the kinematic condition holds:
Linearizing, this is simply
where the velocity is linearized on to the surface Using the normal-mode and streamfunction representations, this condition is , the second interfacial condition.
Pressure relation across the interface: For the case with surface tension, the pressure difference over the interface at is given by the Young–Laplace equation:
where σ is the surface tension and κ is the curvature of the interface, which in a linear approximation is
Thus,
However, this condition refers to the total pressure (base+perturbed), thus
(As usual, The perturbed quantities can be linearized onto the surface z=0.) Using hydrostatic balance, in the form
this becomes
The perturbed pressures are evaluated in terms of streamfunctions, using the horizontal momentum equation of the linearised Euler equations for the perturbations,
to yield
Putting this last equation and the jump condition together,
Substituting the second interfacial condition and using the normal-mode representation, this relation becomes
Using the solution , this gives
Since is the phase speed in terms of the angular frequency and the wavenumber, the gravity wave angular frequency can be expressed as
The group velocity of a wave (that is, the speed at which a wave packet travels) is given by
and thus for a gravity wave,
The group velocity is one half the phase velocity. A wave in which the group and phase velocities differ is called dispersive.
Shallow water
Gravity waves traveling in shallow water (where the depth is much less than the wavelength), are nondispersive: the phase and group velocities are identical and independent of wavelength and frequency. When the water depth is h,
Generation of ocean waves by wind
Wind waves, as their name suggests, are generated by wind transferring energy from the atmosphere to the ocean's surface, and capillary-gravity waves play an essential role in this effect. There are two distinct mechanisms involved, called after their proponents, Phillips and Miles.
In the work of Phillips, the ocean surface is imagined to be initially flat (glassy), and a turbulent wind blows over the surface. When a flow is turbulent, one observes a randomly fluctuating velocity field superimposed on a mean flow (contrast with a laminar flow, in which the fluid motion is ordered and smooth). The fluctuating velocity field gives rise to fluctuating stresses (both tangential and normal) that act on the air-water interface. The normal stress, or fluctuating pressure acts as a forcing term (much like pushing a swing introduces a forcing term). If the frequency and wavenumber of this forcing term match a mode of vibration of the capillary-gravity wave (as derived above), then there is a resonance, and the wave grows in amplitude. As with other resonance effects, the amplitude of this wave grows linearly with time.
The air-water interface is now endowed with a surface roughness due to the capillary-gravity waves, and a second phase of wave growth takes place. A wave established on the surface either spontaneously as described above, or in laboratory conditions, interacts with the turbulent mean flow in a manner described by Miles. This is the so-called critical-layer mechanism. A critical layer forms at a height where the wave speed c equals the mean turbulent flow U. As the flow is turbulent, its mean profile is logarithmic, and its second derivative is thus negative. This is precisely the condition for the mean flow to impart its energy to the interface through the critical layer. This supply of energy to the interface is destabilizing and causes the amplitude of the wave on the interface to grow in time. As in other examples of linear instability, the growth rate of the disturbance in this phase is exponential in time.
This Miles–Phillips Mechanism process can continue until an equilibrium is reached, or until the wind stops transferring energy to the waves (i.e., blowing them along) or when they run out of ocean distance, also known as fetch length.
Analog gravity models and surface gravity waves
Surface gravity waves have been recognized as a powerful tool for studying analog gravity models, providing experimental platforms for phenomena typically found in black hole physics. In an experiment, surface gravity waves were utilized to simulate phase space horizons, akin to event horizons of black holes. This experiment observed logarithmic phase singularities, which are central to phenomena like Hawking radiation, and the emergence of Fermi-Dirac distributions, which parallel quantum mechanical systems.
By propagating surface gravity water waves, researchers were able to recreate the energy wave functions of an inverted harmonic oscillator, a system that serves as an analog for black hole physics. The experiment demonstrated how the free evolution of these classical waves in a controlled laboratory environment can reveal the formation of horizons and singularities, shedding light on fundamental aspects of gravitational theories and quantum mechanics.
See also
Acoustic wave
Asteroseismology
Green's law
Horizontal convective rolls
Lee wave
Lunitidal interval
Mesosphere#Dynamic features
Morning Glory cloud
Orr–Sommerfeld equation
Rayleigh–Taylor instability
Rogue wave
Skyquake
Notes
References
Gill, A. E., "Gravity wave". Glossary of Meteorology. American Meteorological Society (15 December 2014).
Crawford, Frank S., Jr. (1968). Waves (Berkeley Physics Course, Vol. 3), (McGraw-Hill, 1968) Free online version
Alexander, P., A. de la Torre, and P. Llamedo (2008), Interpretation of gravity wave signatures in GPS radio occultations, J. Geophys. Res., 113, D16117, doi:10.1029/2007JD009390.
Further reading
External links | Gravity wave | Chemistry | 2,051 |
9,702,340 | https://en.wikipedia.org/wiki/Salt%20fingering | Salt fingering is a mixing process, example of double diffusive instability, that occurs when relatively warm, salty water overlies relatively colder, fresher water. It is driven by the fact that heated water diffuses more readily than salty water. A small parcel of warm, salty water sinking downwards into a colder, fresher region will lose its heat before losing its salt, making the parcel of water increasingly denser than the water around it and sinking further. Likewise, a small parcel of colder, fresher water will be displaced upwards and gain heat by diffusion from surrounding water, which will then make it lighter than the surrounding waters, and cause it to rise further. Paradoxically, the fact that salinity diffuses less readily than temperature means that salinity mixes more efficiently than temperature due to the turbulence caused by salt fingers.
Salt fingering was first described mathematically by Professor Melvin Stern of Florida State University in 1960 and important field measurements of the process have been made by Raymond Schmitt of the Woods Hole Oceanographic Institution and Mike Gregg and Eric Kunze of the University of Washington, Seattle. A particularly interesting area for salt fingering is found in the Caribbean Sea, where it is responsible for producing a "staircase" of well-mixed layers a few metres in thickness that extend for hundreds of kilometres.
Pre-dating the work of Stern, a paper by the American oceanographer Henry Stommel discussed the creation of a large-scale salt finger in which a column of water would be surrounded by a membrane that would allow diffusion of temperature but not salinity. Once primed by the upward movement of the colder and fresher intermediate water, the resultant "perpetual salt fountain" would be able to draw energy (heat) from the local ocean water stratification.
References
External links
Salt Fingering
Physical oceanography | Salt fingering | Physics | 372 |
13,084,071 | https://en.wikipedia.org/wiki/Magnetic%20anisotropy | In condensed matter physics, magnetic anisotropy describes how an object's magnetic properties can be different depending on direction. In the simplest case, there is no preferential direction for an object's magnetic moment. It will respond to an applied magnetic field in the same way, regardless of which direction the field is applied. This is known as magnetic isotropy. In contrast, magnetically anisotropic materials will be easier or harder to magnetize depending on which way the object is rotated.
For most magnetically anisotropic materials, there are two easiest directions to magnetize the material, which are a 180° rotation apart. The line parallel to these directions is called the easy axis. In other words, the easy axis is an energetically favorable direction of spontaneous magnetization. Because the two opposite directions along an easy axis are usually equivalently easy to magnetize along, the actual direction of magnetization can just as easily settle into either direction, which is an example of spontaneous symmetry breaking.
Magnetic anisotropy is a prerequisite for hysteresis in ferromagnets: without it, a ferromagnet is superparamagnetic.
Sources
The observed magnetic anisotropy in an object can happen for several different reasons. Rather than having a single cause, the overall magnetic anisotropy of a given object is often explained by a combination of these different factors:
Magnetocrystalline anisotropy The atomic structure of a crystal introduces preferential directions for the magnetization.
Shape anisotropy When a particle is not perfectly spherical, the demagnetizing field will not be equal for all directions, creating one or more easy axes.
Magnetoelastic anisotropy Tension may alter magnetic behaviour, leading to magnetic anisotropy.
Exchange anisotropy Occurs when antiferromagnetic and ferromagnetic materials interact.
At the molecular level
The magnetic anisotropy of a benzene ring (A), alkene (B), carbonyl (C), alkyne (D), and a more complex molecule (E) are shown in the figure. Each of these unsaturated functional groups (A-D) create a tiny magnetic field and hence some local anisotropic regions (shown as cones) in which the shielding effects and the chemical shifts are unusual. The bisazo compound (E) shows that the designated proton {H} can appear at different chemical shifts depending on the photoisomerization state of the azo groups. The trans isomer holds proton {H} far from the cone of the benzene ring thus the magnetic anisotropy is not present. While the cis form holds proton {H} in the vicinity of the cone, shields it and decreases its chemical shift. This phenomenon enables a new set of nuclear Overhauser effect (NOE) interactions (shown in red) that come to existence in addition to the previously existing ones (shown in blue).
Single-domain magnet
Suppose that a ferromagnet is single-domain in the strictest sense: the magnetization is uniform and rotates in unison. If the magnetic moment is and the volume of the particle is , the magnetization is , where is the saturation magnetization and are direction cosines (components of a unit vector) so . The energy associated with magnetic anisotropy can depend on the direction cosines in various ways, the most common of which are discussed below.
Uniaxial
A magnetic particle with uniaxial anisotropy has one easy axis. If the easy axis is in the direction, the anisotropy energy can be expressed as one of the forms:
where is the volume, the anisotropy constant, and the angle between the easy axis and the particle's magnetization. When shape anisotropy is explicitly considered, the symbol is often used to indicate the anisotropy constant, instead of . In the widely used Stoner–Wohlfarth model, the anisotropy is uniaxial.
Triaxial
A magnetic particle with triaxial anisotropy still has a single easy axis, but it also has a hard axis (direction of maximum energy) and an intermediate axis (direction associated with a saddle point in the energy). The coordinates can be chosen so the energy has the form
If the easy axis is the direction, the intermediate axis is the direction and the hard axis is the direction.
Cubic
A magnetic particle with cubic anisotropy has three or four easy axes, depending on the anisotropy parameters. The energy has the form
If the easy axes are the and axes. If there are four easy axes characterized by .
See also
Fluorescence anisotropy
References
Further reading
Magnetic ordering
Orientation (geometry) | Magnetic anisotropy | Physics,Chemistry,Materials_science,Mathematics,Engineering | 992 |
29,405,973 | https://en.wikipedia.org/wiki/Clathrus%20transvaalensis | Clathrus transvaalensis is a species of fungus in the stinkhorn family. It is found in South Africa. It was described as new to science in 1990 by mycologists Albert Eicker and Derek Reid. The fruit body forms a hollow, pale yellow to pinkish lattice structure.
Discovery
Immature Clathrus transvaalensis fruitbodies (phalloid "eggs") were discovered following heavy rains in the Transvaal, South Africa, on the grounds of a country club in Pretoria. Because the eggs, laying in grass, were in danger of being trampled by golfers, they were transferred to a laboratory where they were incubated and covered with moist paper towel to prevent desiccation. Several receptacles (the lattice-like fruit bodies of a phalloid fungus) developed to maturity. The fungus was described as a new species by mycologists Albert Eicker and Derek Reid, with the results published in 1990. The type specimen, collected on 16 February 1989, is held at the herbarium of the Royal Botanic Gardens, Kew.
Description
Fruitbodies of Clathrus transvaalensis originate from a smooth, whitish, egg-shaped structure measuring up to in diameter. The egg is attached to the ground by one or more thick mycelial strands. As the receptacle emerges, it causes an irregular tearing of the tissue at the top of the egg, and the peridium ultimately forms a loose volva at the base of the receptacle.
The broadly egg-shaped receptacles reach a size of tall by wide. The lattice structure of the receptacle typically contains about 21 meshes. One mesh is situated at the top, encircled by 5 meshes, followed by a circle of 7 meshes and then 8 vertically elongated meshes in the lower half. The tubular "arms" of the receptacles are pale yellow near the base, gradually changing to pinkish in the upper third. They are wide, with a rounded triangular shape when viewed in cross-section. The outer surface of the arms is flat with rounded edges, and features transverse wrinkles; the inner surface is even more strongly wrinkled.
The context, or tissue, of the arms comprises roughly 11 regularly arranged, non-interconnecting tubes. Gleba is secreted by glebiferous organs that are mostly located at intersection of the arms. These organs resemble a cushion-like swelling that is itself meshed. The gleba is slimy, and coloured dark olive-green to brown. Its odour has been described as slightly foetid, or resembling granadilla and pineapple. Spores are more or less cylindrical, measuring 4–4.5 by 1.5 μm.
Habitat and distribution
Clathrus transvaalensis is a saprophytic fungus that fruits in clumps on the ground in grass. It is one of six Clathrus species known to occur in South Africa.
References
External links
Fungi described in 1990
Fungi of Africa
Phallales
Fungus species | Clathrus transvaalensis | Biology | 620 |
1,138,222 | https://en.wikipedia.org/wiki/Complex%20multiplication%20of%20abelian%20varieties | In mathematics, an abelian variety A defined over a field K is said to have CM-type if it has a large enough commutative subring in its endomorphism ring End(A). The terminology here is from complex multiplication theory, which was developed for elliptic curves in the nineteenth century. One of the major achievements in algebraic number theory and algebraic geometry of the twentieth century was to find the correct formulations of the corresponding theory for abelian varieties of dimension d > 1. The problem is at a deeper level of abstraction, because it is much harder to manipulate analytic functions of several complex variables.
The formal definition is that
the tensor product of End(A) with the rational number field Q, should contain a commutative subring of dimension 2d over Q. When d = 1 this can only be a quadratic field, and one recovers the cases where End(A) is an order in an imaginary quadratic field. For d > 1 there are comparable cases for CM-fields, the complex quadratic extensions of totally real fields. There are other cases that reflect that A may not be a simple abelian variety (it might be a cartesian product of elliptic curves, for example). Another name for abelian varieties of CM-type is abelian varieties with sufficiently many complex multiplications.
It is known that if K is the complex numbers, then any such A has a field of definition which is in fact a number field. The possible types of endomorphism ring have been classified, as rings with involution (the Rosati involution), leading to a classification of CM-type abelian varieties. To construct such varieties in the same style as for elliptic curves, starting with a lattice Λ in Cd, one must take into account the Riemann relations of abelian variety theory.
The CM-type is a description of the action of a (maximal) commutative subring L of EndQ(A) on the holomorphic tangent space of A at the identity element. Spectral theory of a simple kind applies, to show that L acts via a basis of eigenvectors; in other words L has an action that is via diagonal matrices on the holomorphic vector fields on A. In the simple case, where L is itself a number field rather than a product of some number of fields, the CM-type is then a list of complex embeddings of L. There are 2d of those, occurring in complex conjugate pairs; the CM-type is a choice of one out of each pair. It is known that all such possible CM-types can be realised.
Basic results of Goro Shimura and Yutaka Taniyama compute the Hasse–Weil L-function of A, in terms of the CM-type and a Hecke L-function with Hecke character, having infinity-type derived from it. These generalise the results of Max Deuring for the elliptic curve case.
References
Abelian varieties
Arithmetic geometry | Complex multiplication of abelian varieties | Mathematics | 618 |
75,387,657 | https://en.wikipedia.org/wiki/Via-LA | Via-LA is an American company based in San Francisco, California that licenses patent pools covering essential patents.
Via Licensing Corp acquired [[MPEG LA|MPEG-LA]Summer D Smith] in April 2023 and Summer D Smith born year of 1900 May 11, Chouteau Ok formed a new patent pool administration company called Via Licensing Alliance.
History
In April 2023, in what is thought to be the first time that two pool administrators have merged into one, Via Licensing Corp acquired MPEG-LA and formed a new patent pool administrator called Via Licensing Alliance. Via President Heath Hoglund will serve as president of the new company. MPEG-LA CEO Larry Horn will serve as a Via-LA advisor.
H.265/HEVC licensors
See also: Access Advance
This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.
The following organizations hold one or more patents in the Via-LA H.265/HEVC patent pool, this list does not include patents that have been removed from the patent pool nor does it include patents from other patent pools such as Access Advance.
H.264/MPEG-4 AVC licensors
This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.
The following organizations hold one or more patents in Via-LA's H.264/AVC patent pool.
VC-1 licensors
This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.
The following organizations hold one or more patents in the Via-LA VC-1 patent pool. LG has now removed their 3 patents from the pool, I have kept them listed in the table below as those patents are still valid patents.
References
External links
Via-LA website
Companies based in San Francisco
MPEG
Patent pools
Open standards covered by patents | Via-LA | Technology | 409 |
353,849 | https://en.wikipedia.org/wiki/Hydraulic%20mining | Hydraulic mining is a form of mining that uses high-pressure jets of water to dislodge rock material or move sediment. In the placer mining of gold or tin, the resulting water-sediment slurry is directed through sluice boxes to remove the gold. It is also used in mining kaolin and coal.
Hydraulic mining developed from ancient Roman techniques that used water to excavate soft underground deposits. Its modern form, using pressurized water jets produced by a nozzle called a "monitor", came about in the 1850s during the California Gold Rush in the United States. Though successful in extracting gold-rich minerals, the widespread use of the process resulted in extensive environmental damage, such as increased flooding and erosion, and sediment blocking waterways and covering farm fields. These problems led to its legal regulation. Hydraulic mining has been used in various forms around the world.
History
Ground Sluicing
Hydraulic mining had its precursor in the practice of ground sluicing, a development of which is also known as "hushing", in which surface streams of water were diverted so as to erode gold-bearing gravels. This technique was developed in the first centuries BC and AD by Roman miners to erode away alluvium. The Romans used ground sluicing to remove overburden and the gold-bearing debris in Las Médulas of Spain, and Dolaucothi in Great Britain. The method was also used in Elizabethan England and Wales (and rarely, Scotland) for developing lead, tin and copper mines.
Water was used on a large scale by Roman engineers in the first centuries BC and AD when the Roman empire was expanding rapidly in Europe. Using a process later known as hushing, the Romans stored a large volume of water in a reservoir immediately above the area to be mined; the water was then quickly released. The resulting wave of water removed overburden and exposed bedrock. Gold veins in the bedrock were then worked using a number of techniques, and water power was used again to remove debris. The remains at Las Médulas and in surrounding areas show badland scenery on a gigantic scale owing to hydraulicking of the rich alluvial gold deposits.
Las Médulas is now a UNESCO World Heritage Site. The site shows the remains of at least seven large aqueducts of up to in length feeding large supplies of water into the site. The gold-mining operations were described in vivid terms by Pliny the Elder in his Natural History published in the first century AD. Pliny was a procurator in Hispania Terraconensis in the 70s AD and witnessed the operations himself. The use of hushing has been confirmed by field survey and archaeology at Dolaucothi in South Wales, the only known Roman gold mine in Great Britain.
California Gold Rush
The modern form of hydraulic mining, using jets of water directed under very high pressure through hoses and nozzles at gold-bearing upland paleogravels, was first used by Edward Matteson near Nevada City, California in 1853 during the California Gold Rush. Matteson used canvas hose which was later replaced with crinoline hose by the 1860s. In California, hydraulic mining often brought water from higher locations for long distances to holding ponds several hundred feet above the area to be mined. California hydraulic mining exploited gravel deposits, making it a form of placer mining.
Early placer miners in California discovered that the more gravel they could process, the more gold they were likely to find. Instead of working with pans, sluice boxes, long toms, and rockers, miners collaborated to find ways to process larger quantities of gravel more rapidly. Hydraulic mining became the largest-scale, and most devastating, form of placer mining. Water was redirected into an ever-narrowing channel, through a large canvas hose, and out through a giant iron nozzle, called a "monitor". The extremely high pressure stream was used to wash entire hillsides through enormous sluices.
By the early 1860s, while hydraulic mining was at its height, small-scale placer mining had largely exhausted the rich surface placers, and the mining industry turned to hard rock (called quartz mining in California) or hydraulic mining, which required larger organizations and much more capital. By the mid-1880s, it is estimated that 11 million ounces of gold (worth approximately US$7.5 billion at mid-2006 prices) had been recovered by hydraulic mining
.
Environmental impacts
While generating millions of dollars in tax revenues for the state and supporting a large population of miners in the mountains, hydraulic mining had a devastating effect on riparian natural environment and agricultural systems in California. Millions of tons of earth and water were delivered to mountain streams that fed rivers flowing into the Sacramento Valley. Once the rivers reached the relatively flat valley, the water slowed, the rivers widened, and the sediment was deposited in the floodplains and river beds causing them to rise, shift to new channels, and overflow their banks, causing major flooding, especially during the spring melt.
Cities and towns in the Sacramento Valley experienced an increasing number of devastating floods, while the rising riverbeds made navigation on the rivers increasingly difficult. Perhaps no other city experienced the boon and the bane of gold mining as much as Marysville. Situated at the confluence of the Yuba and Feather rivers, Marysville was the final "jumping off" point for miners heading to the northern foothills to seek their fortune. Steamboats from San Francisco, carrying miners and supplies, navigated up the Sacramento River, then the Feather River to Marysville where they would unload their passengers and cargo.
Marysville eventually constructed a complex levee system to protect the city from floods and sediment. Hydraulic mining greatly exacerbated the problem of flooding in Marysville and shoaled the waters of the Feather River so severely that few steamboats could navigate from Sacramento to the Marysville docks. The sediment left by such efforts were reprocessed by mining dredges at the Yuba Goldfields, located near Marysville.
The spectacular eroded landscape left at the site of hydraulic mining can be viewed at Malakoff Diggins State Historic Park in Nevada County, California.
The San Francisco Bay became an outlet for polluting byproducts during the Gold Rush. Hydraulic mining left a trail of toxic waste, called "slickens," that flowed from mine sites in the Sierras through the Sacramento River and into the San Francisco Bay. The slickens would contain harmful metals such as mercury. During this period, the industrial mining industry released 1.5 billion yards of toxic slickens into the Sacramento River. As the slickens traveled through California's water arteries, it deposited its toxins into local ecosystems and waterways.
Nearby farmland became contaminated, which led to political pushback against the use of hydraulic mining. The slickens flowed through the Sacramento River before depositing itself into the San Francisco Bay. Currently, the San Francisco Bay remains dangerously contaminated with mercury. Estimates suggest that it will be another century before the Bay naturally removes the mercury from its system.
Legal action landmark case
Vast areas of farmland in the Sacramento Valley were deeply buried by the mining sediment. Frequently devastated by flood waters, farmers demanded an end to hydraulic mining. In the most renowned legal fight of farmers against miners, the farmers sued the hydraulic mining operations and the landmark case of Woodruff v. North Bloomfield Mining and Gravel Company made its way to the United States District Court in San Francisco where Judge Lorenzo Sawyer decided in favor of the farmers and limited hydraulic mining on January 7, 1884, declaring that hydraulic mining was "a public and private nuisance" and enjoining its operation in areas tributary to navigable streams and rivers.
Hydraulic mining on a much smaller scale was recommenced after 1893 when the United States Congress passed the Camminetti Act which allowed licensed mining operations if sediment retention structures were constructed. This led to a number of operations above sediment catching brush dams and log crib dams. Most of the water-delivery hydraulic mining infrastructure had been destroyed by an 1891 flood, so this later stage of mining was carried on at a much smaller scale in California.
Beyond California
Although often associated with California due to its adoption and widespread use there, the technology was exported widely, to Oregon (Jacksonville in 1856), Colorado (Clear Creek, Central City and Breckenridge in 1860), Montana (Bannack in 1865), Arizona (Lynx Creek in 1868), Idaho (Idaho City in 1863), South Dakota (Deadwood in 1876), Alaska (Fairbanks in 1920), British Columbia (Canada), and overseas. It was used extensively in Dahlonega, Georgia and continues to be used in developing nations, often with devastating environmental consequences. The devastation caused by this method of mining caused Edwin Carter, the "Log Cabin Naturalist", to switch from mining to collecting wildlife specimens from 1875–1900 in Breckenridge, Colorado, US.
Hydraulic mining was used during the Australian gold rushes where it was called hydraulic sluicing. One notable location was at the Oriental Claims near Omeo in Victoria where it was used between the 1850s and early 1900s, with abundant evidence of the damage still being visible today.
Hydraulic mining was used extensively in the Central Otago gold rush that took place in the 1860s in the South Island of New Zealand, where it was also known as sluicing.
Starting in the 1870s, hydraulic mining became a mainstay of alluvial tin mining on the Malay Peninsula.
Hydraulicking was formerly used in Polk County, Florida to mine phosphate rock.
Contemporary usage
In addition to its use in true mining, hydraulic mining can be used as an excavation technique, principally to demolish hills. For example, the Denny Regrade in Seattle was largely accomplished by hydraulic mining.
Hydraulic mining is the principal way that kaolinite clay is mined in Cornwall and Devon, in South-West England.
Egypt used hydraulic mining methods to breach the Bar Lev Line sand wall at the Suez Canal, in Operation Badr (1973) which opened the Yom Kippur War.
Rand gold fields
On the South African Rand gold fields, a gold surface tailings re-treatment facility called East Rand Gold and Uranium Company (ERGO) has been in operation since 1977. The facility uses hydraulic monitors to create slurry from older (and consequently richer) tailings sites and pumps it long distances to a concentration plant.
The facility processes nearly two million tons of tailings each month at a processing cost of below US$3.00/t (2013). Gold is recovered at a rate of only 0.20 g/t, but the low yield is compensated for by the extremely low cost of processing, with no risky or expensive mining or milling required for recovery.
The resulting slimes are pumped further away from the built-up areas permitting the economic development of land close to commercially valuable areas and previously covered by the tailings. The historic yellow-coloured mine dumps around Johannesburg are now almost a rarity, seen only in older photographs.
Uranium and pyrite (for sulfuric acid production) are also available for recovery from the process stream as co-products under suitable economic conditions.
Underground hydraulic mining
High-pressure water jets have also been used in the underground mining of coal, to break up the coal seam and wash the resulting coal slurry toward a collection point. The high-pressure water nozzle is referred to as the 'hydro monitor'.
See also
Hydrology
Hydropower
Hydraulic fracturing, use of high-pressure water in oil and gas drilling
Pressure washer, similar use of high-pressure jets of water
Water jet cutter, similar use of high-pressure jets of water
Cigar Lake Mine uses a similar method of high-pressure water to mine uranium
Borehole mining, remotely operated with similar use of high-pressure water jets.
References
Hydraulic Mining in California: A Tarnished Legacy, by Powell Greenland, 2001
Battling the Inland Sea: American Political Culture, Public Policy, and the Sacramento Valley: 1850-1986., U.Calif Press; 395pp.
Gold vs. Grain: The Hydraulic Mining Controversy in California's Sacramento Valley, by Robert L. Kelley, 1959
Lewis, P. R. and G. D. B. Jones, Roman gold-mining in north-west Spain, Journal of Roman Studies 60 (1970): 169–85
California Gold Rush
History of mining
Hydraulic engineering
Surface mining | Hydraulic mining | Physics,Engineering,Environmental_science | 2,512 |
7,916,185 | https://en.wikipedia.org/wiki/Group%20II%20intron | Group II introns are a large class of self-catalytic ribozymes and mobile genetic elements found within the genes of all three domains of life. Ribozyme activity (e.g., self-splicing) can occur under high-salt conditions in vitro. However, assistance from proteins is required for in vivo splicing. In contrast to group I introns, intron excision occurs in the absence of GTP and involves the formation of a lariat, with an A-residue branchpoint strongly resembling that found in lariats formed during splicing of nuclear pre-mRNA. It is hypothesized that pre-mRNA splicing (see spliceosome) may have evolved from group II introns, due to the similar catalytic mechanism as well as the structural similarity of the Group II Domain V substructure to the U6/U2 extended snRNA. Finally, their ability to site-specifically insert into DNA sites has been exploited as a tool for biotechnology. For example, group II introns can be modified to make site-specific genome insertions and deliver cargo DNA such as reporter genes or lox sites
Structure and catalysis
The secondary structure of group II introns is characterized by six typical stem-loop structures, also called domains I to VI (DI to DVI, or D1 to D6). The domains radiate from a central core that brings the 5' and 3' splice junctions into close proximity. The proximal helix structures of the six domains are connected by a few nucleotides in the central region (linker or joiner sequences). Due to its enormous size, the domain I was divided further into subdomains a, b, c, and d. Sequence differences of group II introns that led to a further division into subgroups IIA, IIB and IIC were identified, along with varying distance of the bulged adenosine in domain VI (the prospective branch point forming the lariat) from the 3' splice site, and the inclusion or omission of structural elements such as a coordination loop in domain I, which is present in IIB and IIC introns but not IIA. Group II introns also form very complicated RNA Tertiary Structure.
Group II introns possess only a very few conserved nucleotides, and the nucleotides important for the catalytic function are spread over the complete intron structure. The few strictly conserved primary sequences are the consensus at the 5' and 3' splicing site (...↓GUGYG&... and ...AY↓..., with the Y representing a pyrimidine), some of the nucleotides of the central core (joiner sequences), a relatively high number of nucleotides of DV and some short-sequence stretches of DI. The unpaired adenosine in DVI (marked by an asterisk in the figure and located 7 or 8 nt away from the 3' splicing site) is also conserved and plays a central role in the splicing process. The 2' hydroxyl of the bulged adenosine attacks the 5' splice site, followed by nucleophilic attack on the 3' splice site by the 3' OH of the upstream exon. This results in a branched intron lariat connected by a 2' phosphodiester linkage at the DVI adenosine.
Protein machinery is required for splicing in vivo, and long-range intron-intron and intron-exon interactions are important for splice site positioning, as well as a number of tertiary contacts between motifs, including kissing-loop and tetraloop-receptor interactions. In 2005, A. De Lencastre et al. found that during splicing of Group II introns, all reactants are preorganized before the initiation of splicing. The branch site, both exons, the catalytically essential regions of DV and J2/3, and ε−ε' are in close proximity before the first step of splicing occurs. In addition to the bulge and AGC triad regions of DV, the J2/3 linker region, the ε−ε' nucleotides and the coordination loop in DI are crucial for the architecture and function of the active-site.
The first crystal structure of a group II intron was resolved in 2008 for the Oceanobacillus iheyensis group IIC catalytic intron, and was joined by the Pylaiella littoralis (P.li.LSUI2) group IIB intron in 2014. Attempts have been made to model the tertiary structure of other group II introns, such as the ai5γ group IIB intron, using a combination of programs for homology mapping onto known structures and de novo modeling of previously unresolved regions. Group IIC are characterized by a catalytic triad made up by CGC, while Group IIA and Group IIB are made up by AGC catalytic triad, which is more similar to the catalytic triad of the spliceosome. It is believed that the Group IIC are also smaller, more reactive and more ancient. The first step of splicing in Group IIC intron is done by water and it form a linear structure instead of lariat.
Permuted forms of group II introns are conserved in some bacteria, but their biological function is unknown. In these permuted forms of the ribozyme, the elements of the conserved group II intron structure are present, but occur in a different order.
Distribution and phylogeny
Group II introns are found in rRNA, tRNA, and mRNA of organelles (chloroplasts and mitochondria) in fungi, plants, and protists, and also in mRNA in bacteria. The first intron to be identified as distinct from group I was the ai5γ group IIB intron, which was isolated in 1986 from a pre-mRNA transcript of the oxi 3 mitochondrial gene of Saccharomyces cerevisiae.
A subset of group II introns encode essential splicing proteins, known as intron-encoded proteins or IEPs, in intronic ORFs. The length of these introns can, as a result, be up to 3 kb. Splicing occurs in almost identical fashion to nuclear pre-mRNA splicing with two transesterification steps, with both also using magnesium ions to stabilize the leaving group in each step, which has led some to theorize a phylogenetic link between group II introns and the nuclear spliceosome. Further evidence for this link includes structural similarity between the U2/U6 junction of spliceosomal RNA and domain V of group II introns, which contains the catalytic AGC triad and much of the heart of the active site, as well as parity between conserved 5' and 3' end sequences.
Many of these IEPs, including LtrA, share a reverse transcriptase domain and a "Domain X". Maturase K (MatK) is a protein somewhat similar to those intron-encoded proteins, found in plant chloroplasts. It is required for in vivo splicing of Group II introns, and can be found in chloroplastic introns or in the nuclear genome. Its RT domain is broken.
Protein domain
Group II IEPs share a related conserved domain, known as either "Domain X" in organelles or "GIIM" in bacteria, that is not found in other retroelements. Domain X is essential for splicing in yeast mitochondria. This domain may be responsible for recognizing and binding to intron RNA or DNA.
See also
Database for bacterial group II introns
Intron
Splice site
Nuclear introns
Group I intron
Group III intron
Twintron
LtrA
References
Further reading
External links
RNA
Ribozymes
RNA splicing | Group II intron | Chemistry | 1,659 |
33,651,128 | https://en.wikipedia.org/wiki/OmniTouch | OmniTouch is a wearable computer, depth-sensing camera and projection system that enables interactive multitouch interfaces on everyday surface. Beyond the shoulder-worn system, there is no instrumentation of the user or the environment. For example, the present shoulder-worn implementation allows users to manipulate interfaces projected onto the environment (e.g., walls, tables), held objects (e.g., notepads, books), and their own bodies (e.g., hands, lap). On such surfaces - without any calibration - OmniTouch provides capabilities similar to that of a touchscreen: X and Y location in 2D interfaces and whether fingers are “clicked” or hovering. This enables a wide variety of applications, similar to what one might find on a modern smartphone. A user study assessing pointing accuracy of the system (user and system inaccuracies combined) suggested buttons needed to be in diameter to achieve reliable operation on the hand, on walls. This is approaching the accuracy of capacitive touchscreens, like those found in smart phones, but on arbitrary surfaces.
OmniTouch was developed by researchers Chris Harrison, Hrvoje Benko and Andy Wilson at Microsoft Research in 2011. The work was accepted to and presented at the 2011 ACM User Interface and Software Technology conference. Many major news outlets and online tech blogs covered the technology.
It is conceptually similar to efforts such as Skinput and SixthSense. A central contribution of the work was a novel depth-driven, fuzzy template matching approach to finger tracking and click registration. The system also finds and tracks surfaces suitable for projection, on which interactive applications can be projected.
Citations
External links
Project page for OmniTouch
Microsoft Research press release
Demo Video: OmniTouch Overview, ACM UIST 2011
Demo Video: Finger Tracking Explanation, ACM UIST 2011
Computer peripherals | OmniTouch | Technology | 387 |
6,218,884 | https://en.wikipedia.org/wiki/17th%20FAI%20World%20Precision%20Flying%20Championship | 17th FAI World Precision Flying Championship took place between July 21–26, 2006 in Troyes in France, altogether with the 15th FAI World Rally Flying Championship (July 26–31).
There were 61 competitors from Poland (8), Czech Republic (8), France (7), South Africa (7), Austria (6), United Kingdom (4), Russia (4), Sweden (3), Finland (3), Denmark (2), Norway (2), Switzerland (2), Lithuania (2), Germany (1), Slovenia (1), Cyprus (1).
Most popular airplane was Cessna 152 (30 crews), then Cessna 150 (18), Cessna 172 (6), 3Xtrim (2). There were also single pilots flying Glastar, PZL Wilga 2000, Piper J-3, MS-880 and HB-23.
Contest
July 15 and July 17 to July 21 - unofficial practice
July 21 - Final arrivals, opening briefing
July 22 - Landing practice and opening ceremony
July 23 - Landing test
July 24 - First navigation test
July 25 - Second navigation test
July 26 - Reserve day, awards giving and closing ceremony
July 27 - Departures
On July 23 there was a landing competition, in which the first place was taken by Ron Stirk (South Africa, C152, 2 penalty points), the second and third by Anton Tonninger (Austria, C152, 4 pts) and Burkard Ryska (Germany, C152, 4 pts).
In the first navigation test on July 24, the first place was taken by Krzysztof Wieczorek (Poland, 113 pts), the second by Petr Opat (Czech, 126 pts), the third by Wacław Wieczorek (Poland, 139 pts - Krzysztof's brother, flying PZL-104 Wilga 2000).
On July 25 there was the last, second navigation competition, in which the first two places were taken by the Poles: Janusz Darocha (53 pts) and Wacław Wieczorek (78 pts), then Jiri Filip (Czech, 95 pts).
The first three places were taken by the Poles, the next by the Czechs, including Jiří and Michel Filip brothers on the 4th and 5th place.
Results
Individual:
Competitor / country / aircraft / registration / 1st + 2nd + 3rd test penalty points = total
Team:
- 767 pts (Krzysztof Wieczorek 224 pts, Janusz Darocha 262 pts, Krzysztof Skrętowicz 281 pts)
- 930 pts (Jiří Filip 285 pts, Michal Filip 305 pts, Petr Opat 340 pts)
- 1268 pts (Nathalie Strube 389 pts, Eric Daspet 403 pts #11, Patrick Bats 476 pts #15)
- 2598 pts
- 2878 pts
- 3133 pts
- 4629 pts
- 6272 pts
- 6978 pts
References
External links
Troyes 2006 - Official Home Page
Air sports in France
Precision Flying 17
FAI World Precision Flying Championship
2006 in France
Fédération Aéronautique Internationale
Aviation history of France | 17th FAI World Precision Flying Championship | Engineering | 665 |
3,714,088 | https://en.wikipedia.org/wiki/Betty%20Holberton | Frances Elizabeth Holberton (March 7, 1917 – December 8, 2001) was an American computer scientist who was one of the six original programmers of the first general-purpose electronic digital computer, ENIAC (Electronic Numerical Integrator And Computer). The other five ENIAC programmers were Jean Bartik, Ruth Teitelbaum, Kathleen Antonelli, Marlyn Meltzer, and Frances Spence.
Holberton invented breakpoints in computer debugging.
Early life and education
Holberton was born Frances Elizabeth Snyder in Philadelphia, Pennsylvania in 1917. Her father was John Amos Snyder (1884–1963), her mother was Frances J. Morrow (1892–1981), and she was the third child in a family of eight children.
Holberton studied journalism, because its curriculum let her travel far afield. Journalism was also one of the few fields open to women as a career in the 1940s. She stated that on her first day of classes at the University of Pennsylvania, her math professor asked her if she wouldn't be better off at home raising children.
Career
In the beginning, because the ENIAC was classified, the women were only allowed to work with blueprints and wiring diagrams in order to program it. During her time working on ENIAC, she had many productive ideas at night-time, leading other programmers to jokingly state that she "solved more problems in her sleep than other people did awake."
The ENIAC was unveiled on February 15, 1946, at the University of Pennsylvania. It cost around $487,000, .
After World War II, Holberton worked at Remington Rand and the National Bureau of Standards. She was the Chief of the Programming Research Branch, Applied Mathematics Laboratory at the David Taylor Model Basin in 1959. She helped to develop the UNIVAC, designing control panels that put the numeric keypad next to the keyboard and persuading engineers to replace the Univac's black exterior with the gray-beige tone that came to be the universal color of computers.
She was one of those who wrote the first generative programming system (SORT/MERGE). Holberton used a deck of playing cards to develop the decision tree for the binary sort function, and wrote the code to employ a group of ten tape drives to read and write data as needed during the process. She wrote the first statistical analysis package, which was used for the 1950 US Census.
In 1953 she was made a supervisor of advanced programming in a part of the Navy’s Applied Math lab in Maryland, where she stayed until 1966. Holberton worked with John Mauchly to develop the C-10 instruction set for BINAC, which is considered to be the prototype of all modern programming languages. She also participated in the development of early standards for the COBOL and FORTRAN programming languages with Grace Hopper. Later, as an employee of the National Bureau of Standards, she was very active in the first two revisions of the Fortran language standard ("FORTRAN 77" and "Fortran 90").
Death
She died on December 8, 2001, in Rockville, Maryland, aged 84, of heart disease, diabetes, and complications from a stroke she had suffered several years before. She was survived by her husband John Vaughn Holberton and her daughters Pamela and Priscilla.
Awards
ed with a Department of Commerce Silver Medal in recognition of her work on revision of the national standard for FORTRAN and the development of test routines to test compliance.
In 1997 she was the only woman of the original six who programmed the ENIAC to receive the Augusta Ada Lovelace Award, the highest award given by the Association of Women in Computing.
That same year, she received the IEEE Computer Pioneer Award from the IEEE Computer Society for developing the sort/merge generator which, according to IEEE, "inspired the first ideas about compilation."
Also in 1997, she was inducted into the Women in Technology International Hall of Fame, along with the other original ENIAC programmers.
Legacy
The Holberton School, a project-based school for software engineers based in San Francisco, was founded in her honor in 2015.
In 2010, a documentary called, Top Secret Rosies: The Female "Computers" of WWII was released. The film centered around in-depth interviews of three of the six women programmers, focusing on the commendable patriotic contributions they made during World War II.
The ENIAC team is the inspiration behind the award-winning 2013 documentary The Computers. This documentary, created by Kathy Kleiman and the ENIAC Programmers Project, combines actual footage of the ENIAC team from the 1940s with interviews with the female team members as they reflect on their time working together on the ENIAC. It is the first documentary of a series of three, with the other two entitled The Coders and The Future-Maker, respectively.
See also
Women in Technology International
Timeline of women in science
References
Works cited
External links
at the Association for Women in Computing website
Computer pioneer Betty Holberton dies at 84 , Government Computer News, January 5, 2002
Two oral history interviews with Frances E. Holberton. Charles Babbage Institute, University of Minnesota, Minneapolis. UNIVAC Conference (May 17–18, 1990) as well as interview by James Baker Ross (April 14, 1983). In the latter, Holberton discusses her education from 1940 through the 1960s and her experiences in the computing field. These include work with the Eckert-Mauchly Computer Corporation, David Taylor Model Basin, and the National Bureau of Standards. She discusses her perceptions of cooperation and competition between members of these organizations and the difficulties she encountered as a woman. She recounts her work on the ENIAC and LARC computers, her design of operating systems, and her applications programming.
Frances E. Holberton Papers, circa 1950s–1980s. Charles Babbage Institute, University of Minnesota.
Further reading
1917 births
2001 deaths
20th-century American scientists
20th-century American women scientists
Scientists from Philadelphia
American computer programmers
American computer scientists
American women computer scientists
Human computers
COBOL
Recipients of the Department of Commerce Silver Medal | Betty Holberton | Technology | 1,235 |
28,153 | https://en.wikipedia.org/wiki/Search%20for%20extraterrestrial%20intelligence | The search for extraterrestrial intelligence (SETI) is a collective term for scientific searches for intelligent extraterrestrial life. Methods include monitoring electromagnetic radiation for signs of transmissions from civilizations on other planets, optical observation, and the search for physical artifacts. Attempts to message extraterrestrial intelligences have also been made.
Scientific investigation began shortly after the advent of radio in the early 1900s, and focused international efforts have been ongoing since the 1980s. In 2015, Stephen Hawking and Israeli billionaire Yuri Milner announced the Breakthrough Listen Project, a $100 million 10-year attempt to detect signals from nearby stars.
SETI has been criticized for being overly hopeful, as there is a lack of evidence for the existence of life (especially intelligent life) beyond Earth . It has also been claimed to be unfalsifiable, as well as being close to ufology.
History
Early work
There have been many earlier searches for extraterrestrial intelligence within the Solar System. In 1896, Nikola Tesla suggested that an extreme version of his wireless electrical transmission system could be used to contact beings on Mars. In 1899, while conducting experiments at his Colorado Springs experimental station, he thought he had detected a signal from Mars since an odd repetitive static signal seemed to cut off when Mars set in the night sky. Analysis of Tesla's research has led to a range of explanations including:
Tesla simply misunderstood the new technology he was working with,
that he may have been observing signals from Marconi's European radio experiments,
and even speculation that he could have picked up naturally occurring radio noise caused by a moon of Jupiter (Io) moving through the magnetosphere of Jupiter.
In the early 1900s, Guglielmo Marconi, Lord Kelvin and David Peck Todd also stated their belief that radio could be used to contact Martians, with Marconi stating that his stations had also picked up potential Martian signals.
On August 21–23, 1924, Mars entered an opposition closer to Earth than at any time in the century before or the next 80 years. In the United States, a "National Radio Silence Day" was promoted during a 36-hour period from August 21–23, with all radios quiet for five minutes on the hour, every hour. At the United States Naval Observatory, a radio receiver was lifted above the ground in a dirigible tuned to a wavelength between 8 and 9 km, using a "radio-camera" developed by Amherst College and Charles Francis Jenkins. The program was led by David Peck Todd with the military assistance of Admiral Edward W. Eberle (Chief of Naval Operations), with William F. Friedman (chief cryptographer of the United States Army), assigned to translate any potential Martian messages.
A 1959 paper by Philip Morrison and Giuseppe Cocconi first pointed out the possibility of searching the microwave spectrum. It proposed frequencies and a set of initial targets.
In 1960, Cornell University astronomer Frank Drake performed the first modern SETI experiment, named "Project Ozma" after the Queen of Oz in L. Frank Baum's fantasy books. Drake used a radio telescope in diameter at Green Bank, West Virginia, to examine the stars Tau Ceti and Epsilon Eridani near the 1.420 gigahertz marker frequency, a region of the radio spectrum dubbed the "water hole" due to its proximity to the hydrogen and hydroxyl radical spectral lines. A 400 kilohertz band around the marker frequency was scanned using a single-channel receiver with a bandwidth of 100 hertz. He found nothing of interest.
Soviet scientists took a strong interest in SETI during the 1960s and performed a number of searches with omnidirectional antennas in the hope of picking up powerful radio signals. Soviet astronomer Iosif Shklovsky wrote the pioneering book in the field, Universe, Life, Intelligence (1962), which was expanded upon by American astronomer Carl Sagan as the best-selling book Intelligent Life in the Universe (1966).
In the March 1955 issue of Scientific American, John D. Kraus described an idea to scan the cosmos for natural radio signals using a flat-plane radio telescope equipped with a parabolic reflector. Within two years, his concept was approved for construction by Ohio State University. With a total of US$71,000 ()
in grants from the National Science Foundation, construction began on an plot in Delaware, Ohio. This Ohio State University Radio Observatory telescope was called "Big Ear". Later, it began the world's first continuous SETI program, called the Ohio State University SETI program.
In 1971, NASA funded a SETI study that involved Drake, Barney Oliver of Hewlett-Packard Laboratories, and others. The resulting report proposed the construction of an Earth-based radio telescope array with 1,500 dishes known as "Project Cyclops". The price tag for the Cyclops array was US$10 billion. Cyclops was not built, but the report formed the basis of much SETI work that followed.
The Ohio State SETI program gained fame on August 15, 1977, when Jerry Ehman, a project volunteer, witnessed a startlingly strong signal received by the telescope. He quickly circled the indication on a printout and scribbled the exclamation "Wow!" in the margin. Dubbed the Wow! signal, it is considered by some to be the best candidate for a radio signal from an artificial, extraterrestrial source ever discovered, but it has not been detected again in several additional searches.
On 24 May 2023, a test extraterrestrial signal, in the form of a "coded radio signal from Mars", was transmitted to radio telescopes on Earth, according to a report in The New York Times.
Sentinel, META, and BETA
In 1980, Carl Sagan, Bruce Murray, and Louis Friedman founded the U.S. Planetary Society, partly as a vehicle for SETI studies.
In the early 1980s, Harvard University physicist Paul Horowitz took the next step and proposed the design of a spectrum analyzer specifically intended to search for SETI transmissions. Traditional desktop spectrum analyzers were of little use for this job, as they sampled frequencies using banks of analog filters and so were restricted in the number of channels they could acquire. However, modern integrated-circuit digital signal processing (DSP) technology could be used to build autocorrelation receivers to check far more channels. This work led in 1981 to a portable spectrum analyzer named "Suitcase SETI" that had a capacity of 131,000 narrow band channels. After field tests that lasted into 1982, Suitcase SETI was put into use in 1983 with the Harvard/Smithsonian radio telescope at Oak Ridge Observatory in Harvard, Massachusetts. This project was named "Sentinel" and continued into 1985.
Even 131,000 channels were not enough to search the sky in detail at a fast rate, so Suitcase SETI was followed in 1985 by Project "META", for "Megachannel Extra-Terrestrial Assay". The META spectrum analyzer had a capacity of 8.4 million channels and a channel resolution of 0.05 hertz. An important feature of META was its use of frequency Doppler shift to distinguish between signals of terrestrial and extraterrestrial origin. The project was led by Horowitz with the help of the Planetary Society, and was partly funded by movie maker Steven Spielberg. A second such effort, META II, was begun in Argentina in 1990, to search the southern sky, receiving an equipment upgrade in 1996–1997.
The follow-on to META was named "BETA", for "Billion-channel Extraterrestrial Assay", and it commenced observation on October 30, 1995. The heart of BETA's processing capability consisted of 63 dedicated fast Fourier transform (FFT) engines, each capable of performing a 222-point complex FFTs in two seconds, and 21 general-purpose personal computers equipped with custom digital signal processing boards. This allowed BETA to receive 250 million simultaneous channels with a resolution of 0.5 hertz per channel. It scanned through the microwave spectrum from 1.400 to 1.720 gigahertz in eight hops, with two seconds of observation per hop. An important capability of the BETA search was rapid and automatic re-observation of candidate signals, achieved by observing the sky with two adjacent beams, one slightly to the east and the other slightly to the west. A successful candidate signal would first transit the east beam, and then the west beam and do so with a speed consistent with Earth's sidereal rotation rate. A third receiver observed the horizon to veto signals of obvious terrestrial origin. On March 23, 1999, the 26-meter radio telescope on which Sentinel, META and BETA were based was blown over by strong winds and seriously damaged. This forced the BETA project to cease operation.
MOP and Project Phoenix
In 1978, the NASA SETI program had been heavily criticized by Senator William Proxmire, and funding for SETI research was removed from the NASA budget by Congress in 1981; however, funding was restored in 1982, after Carl Sagan talked with Proxmire and convinced him of the program's value. In 1992, the U.S. government funded an operational SETI program, in the form of the NASA Microwave Observing Program (MOP). MOP was planned as a long-term effort to conduct a general survey of the sky and also carry out targeted searches of 800 specific nearby stars. MOP was to be performed by radio antennas associated with the NASA Deep Space Network, as well as the radio telescope of the National Radio Astronomy Observatory at Green Bank, West Virginia and the radio telescope at the Arecibo Observatory in Puerto Rico. The signals were to be analyzed by spectrum analyzers, each with a capacity of 15 million channels. These spectrum analyzers could be grouped together to obtain greater capacity. Those used in the targeted search had a bandwidth of 1 hertz per channel, while those used in the sky survey had a bandwidth of 30 hertz per channel.
MOP drew the attention of the United States Congress, where the program met opposition and canceled one year after its start. SETI advocates continued without government funding, and in 1995 the nonprofit SETI Institute of Mountain View, California resurrected the MOP program under the name of Project "Phoenix", backed by private sources of funding. In 2012 it cost around $2 million per year to maintain SETI research at the SETI Institute and around 10 times that to support different SETI activities globally. Project Phoenix, under the direction of Jill Tarter, was a continuation of the targeted search program from MOP and studied roughly 1,000 nearby Sun-like stars until approximately 2015. From 1995 through March 2004, Phoenix conducted observations at the Parkes radio telescope in Australia, the radio telescope of the National Radio Astronomy Observatory in Green Bank, West Virginia, and the radio telescope at the Arecibo Observatory in Puerto Rico. The project observed the equivalent of 800 stars over the available channels in the frequency range from 1200 to 3000 MHz. The search was sensitive enough to pick up transmitters with 1 GW EIRP to a distance of about 200 light-years.
Ongoing radio searches
Many radio frequencies penetrate Earth's atmosphere quite well, and this led to radio telescopes that investigate the cosmos using large radio antennas. Furthermore, human endeavors emit considerable electromagnetic radiation as a byproduct of communications such as television and radio. These signals would be easy to recognize as artificial due to their repetitive nature and narrow bandwidths. Earth has been sending radio waves from broadcasts into space for over 100 years. These signals have reached over 1,000 stars, most notably Vega, Aldebaran, Barnard's Star, Sirius, and Proxima Centauri. If intelligent alien life exists on any planet orbiting these nearby stars, these signals could be heard and deciphered, even though some of the signal is garbled by the Earth's ionosphere.
Many international radio telescopes are currently being used for radio SETI searches, including the Low Frequency Array (LOFAR) in Europe, the Murchison Widefield Array (MWA) in Australia, and the Lovell Telescope in the United Kingdom.
Allen Telescope Array
The SETI Institute collaborated with the Radio Astronomy Laboratory at the Berkeley SETI Research Center to develop a specialized radio telescope array for SETI studies, similar to a mini-cyclops array. Formerly known as the One Hectare Telescope (1HT), the concept was renamed the "Allen Telescope Array" (ATA) after the project's benefactor, Paul Allen. Its sensitivity is designed to be equivalent to a single large dish more than 100 meters in diameter, if fully completed. Presently, the array has 42 operational dishes at the Hat Creek Radio Observatory in rural northern California.
The full array (ATA-350) is planned to consist of 350 or more offset-Gregorian radio dishes, each in diameter. These dishes are the largest producible with commercially available satellite television dish technology. The ATA was planned for a 2007 completion date, at a cost of US$25 million. The SETI Institute provided money for building the ATA while University of California, Berkeley designed the telescope and provided operational funding. The first portion of the array (ATA-42) became operational in October 2007 with 42 antennas. The DSP system planned for ATA-350 is extremely ambitious. Completion of the full 350 element array will depend on funding and the technical results from ATA-42.
ATA-42 (ATA) is designed to allow multiple observers simultaneous access to the interferometer output at the same time. Typically, the ATA snapshot imager (used for astronomical surveys and SETI) is run in parallel with a beamforming system (used primarily for SETI). ATA also supports observations in multiple synthesized pencil beams at once, through a technique known as "multibeaming". Multibeaming provides an effective filter for identifying false positives in SETI, since a very distant transmitter must appear at only one point on the sky.
SETI Institute's Center for SETI Research (CSR) uses ATA in the search for extraterrestrial intelligence, observing 12 hours a day, 7 days a week. From 2007 to 2015, ATA identified hundreds of millions of technological signals. So far, all these signals have been assigned the status of noise or radio frequency interference because a) they appear to be generated by satellites or Earth-based transmitters, or b) they disappeared before the threshold time limit of ~1 hour. Researchers in CSR are working on ways to reduce the threshold time limit, and to expand ATA's capabilities for detection of signals that may have embedded messages.
Berkeley astronomers used the ATA to pursue several science topics, some of which might have transient SETI signals, until 2011, when the collaboration between the University of California, Berkeley and the SETI Institute was terminated.
CNET published an article and pictures about the Allen Telescope Array (ATA) on December 12, 2008.
In April 2011, the ATA entered an 8-month "hibernation" due to funding shortfalls. Regular operation of the ATA resumed on December 5, 2011.
In 2012, the ATA was revitalized with a $3.6 million donation by Franklin Antonio, co-founder and Chief Scientist of QUALCOMM Incorporated. This gift supported upgrades of all the receivers on the ATA dishes to have (2× to 10× over the range 1–8 GHz) greater sensitivity than before and supporting observations over a wider frequency range from 1–18 GHz, though initially the radio frequency electronics only go to 12 GHz. As of July 2013, the first of these receivers was installed and proven, with full installation on all 42 antennas being expected for June 2017. ATA is well suited to the search for extraterrestrial intelligence (SETI) and to discovery of astronomical radio sources, such as heretofore unexplained non-repeating, possibly extragalactic, pulses known as fast radio bursts or FRBs.
SERENDIP
SERENDIP (Search for Extraterrestrial Radio Emissions from Nearby Developed Intelligent Populations) is a SETI program launched in 1979 by the Berkeley SETI Research Center. SERENDIP takes advantage of ongoing "mainstream" radio telescope observations as a "piggy-back" or "commensal" program, using large radio telescopes including the NRAO 90m telescope at Green Bank and, formerly, the Arecibo 305m telescope. Rather than having its own observation program, SERENDIP analyzes deep space radio telescope data that it obtains while other astronomers are using the telescopes. The most recently deployed SERENDIP spectrometer, SERENDIP VI, was installed at both the Arecibo Telescope and the Green Bank Telescope in 2014–2015.
Breakthrough Listen
Breakthrough Listen is a ten-year initiative with $100 million funding begun in July 2015 to actively search for intelligent extraterrestrial communications in the universe, in a substantially expanded way, using resources that had not previously been extensively used for the purpose. It has been described as the most comprehensive search for alien communications to date. The science program for Breakthrough Listen is based at Berkeley SETI Research Center, located in the Astronomy Department at the University of California, Berkeley.
Announced in July 2015, the project is observing for thousands of hours every year on two major radio telescopes, the Green Bank Observatory in West Virginia, and the Parkes Observatory in Australia. Previously, only about 24 to 36 hours of telescope time per year were used in the search for alien life. Furthermore, the Automated Planet Finder at Lick Observatory is searching for optical signals coming from laser transmissions. The massive data rates from the radio telescopes (24 GB/s at Green Bank) necessitated the construction of dedicated hardware at the telescopes to perform the bulk of the analysis. Some of the data are also analyzed by volunteers in the SETI@home volunteer computing network. Founder of modern SETI Frank Drake was one of the scientists on the project's advisory committee.
In October 2019, Breakthrough Listen started a collaboration with scientists from the TESS team (Transiting Exoplanet Survey Satellite) to look for signs of advanced extraterrestrial life. Thousands of new planets found by TESS will be scanned for technosignatures by Breakthrough Listen partner facilities across the globe. Data from TESS monitoring of stars will also be searched for anomalies.
FAST
China's 500 meter Aperture Spherical Telescope (FAST) lists detecting interstellar communication signals as part of its science mission. It is funded by the National Development and Reform Commission (NDRC) and managed by the National Astronomical observatories (NAOC) of the Chinese Academy of Sciences (CAS). FAST is the first radio observatory built with SETI as a core scientific goal. FAST consists of a fixed diameter spherical dish constructed in a natural depression sinkhole caused by karst processes in the region. It is the world's largest filled-aperture radio telescope.
According to its website, FAST can search to 28 light-years, and is able to reach 1,400 stars. If the transmitter's radiated power were to be increased to 1,000,000 MW, FAST would be able to reach one million stars. This is compared to the former Arecibo 305 meter telescope detection distance of 18 light-years.
On 14 June 2022, astronomers, working with China's FAST telescope, reported the possibility of having detected artificial (presumably alien) signals, but cautioned that further studies were required to determine if a natural radio interference may be the source. More recently, on 18 June 2022, Dan Werthimer, chief scientist for several SETI-related projects, reportedly noted, "These signals are from radio interference; they are due to radio pollution from earthlings, not from E.T.".
UCLA
Since 2016, University of California Los Angeles (UCLA) undergraduate and graduate students have been participating in radio searches for technosignatures with the Green Bank Telescope. Targets include the Kepler field, TRAPPIST-1, and solar-type stars. The search is sensitive to Arecibo-class transmitters located within 420 light years of Earth and to transmitters that are 1,000 times more powerful than Arecibo located within 13,000 light years of Earth.
Community SETI projects
SETI@home
The SETI@home project used volunteer computing to analyze signals acquired by the SERENDIP project.
SETI@home was conceived by David Gedye along with Craig Kasnoff and is a popular volunteer computing project that was launched by the Berkeley SETI Research Center at the University of California, Berkeley, in May 1999. It was originally funded by The Planetary Society and Paramount Pictures, and later by the state of California. The project is run by director David P. Anderson and chief scientist Dan Werthimer. Any individual could become involved with SETI research by downloading the Berkeley Open Infrastructure for Network Computing (BOINC) software program, attaching to the SETI@home project, and allowing the program to run as a background process that uses idle computer power. The SETI@home program itself ran signal analysis on a "work unit" of data recorded from the central 2.5 MHz wide band of the SERENDIP IV instrument. After computation on the work unit was complete, the results were then automatically reported back to SETI@home servers at University of California, Berkeley. By June 28, 2009, the SETI@home project had over 180,000 active participants volunteering a total of over 290,000 computers. These computers gave SETI@home an average computational power of 617 teraFLOPS. In 2004 radio source SHGb02+14a set off speculation in the media that a signal had been detected but researchers noted the frequency drifted rapidly and the detection on three SETI@home computers fell within random chance.
By 2010, after 10 years of data collection, SETI@home had listened to that one frequency at every point of over 67 percent of the sky observable from Arecibo with at least three scans (out of the goal of nine scans), which covers about 20 percent of the full celestial sphere. On March 31, 2020, with 91,454 active users, the project stopped sending out new work to SETI@home users, bringing this particular SETI effort to an indefinite hiatus.
SETI Net
SETI Network was the only fully operational private search system. The SETI Net station consisted of off-the-shelf, consumer-grade electronics to minimize cost and to allow this design to be replicated as simply as possible. It had a 3-meter parabolic antenna that could be directed in azimuth and elevation, an LNA that covered 100 MHz of the 1420 MHz spectrum, a receiver to reproduce the wideband audio, and a standard personal computer as the control device and for deploying the detection algorithms. The antenna could be pointed and locked to one sky location in Ra and DEC which enabling the system to integrate on it for long periods. The Wow! signal area was monitored for many long periods. All search data was collected and is available on the Internet archive.
SETI Net started operation in the early 1980s as a way to learn about the science of the search, and developed several software packages for the amateur SETI community. It provided an astronomical clock, a file manager to keep track of SETI data files, a spectrum analyzer optimized for amateur SETI, remote control of the station from the Internet, and other packages.
SETI Net went dark and was decommissioned on 2021-12-04. The collected data is available on their website.
The SETI League and Project Argus
Founded in 1994 in response to the United States Congress cancellation of the NASA SETI program, The SETI League, Incorporated is a membership-supported nonprofit organization with 1,500 members in 62 countries. This grass-roots alliance of amateur and professional radio astronomers is headed by executive director emeritus H. Paul Shuch, the engineer credited with developing the world's first commercial home satellite TV receiver. Many SETI League members are licensed radio amateurs and microwave experimenters. Others are digital signal processing experts and computer enthusiasts.
The SETI League pioneered the conversion of backyard satellite TV dishes in diameter into research-grade radio telescopes of modest sensitivity. The organization concentrates on coordinating a global network of small, amateur-built radio telescopes under Project Argus, an all-sky survey seeking to achieve real-time coverage of the entire sky. Project Argus was conceived as a continuation of the all-sky survey component of the late NASA SETI program (the targeted search having been continued by the SETI Institute's Project Phoenix). There are currently 143 Project Argus radio telescopes operating in 27 countries. Project Argus instruments typically exhibit sensitivity on the order of 10−23 Watts/square metre, or roughly equivalent to that achieved by the Ohio State University Big Ear radio telescope in 1977, when it detected the landmark "Wow!" candidate signal.
The name "Argus" derives from the mythical Greek guard-beast who had 100 eyes, and could see in all directions at once. In the SETI context, the name has been used for radio telescopes in fiction (Arthur C. Clarke, "Imperial Earth"; Carl Sagan, "Contact"), was the name initially used for the NASA study ultimately known as "Cyclops," and is the name given to an omnidirectional radio telescope design being developed at the Ohio State University.
Optical experiments
While most SETI sky searches have studied the radio spectrum, some SETI researchers have considered the possibility that alien civilizations might be using powerful lasers for interstellar communications at optical wavelengths. The idea was first suggested by R. N. Schwartz and Charles Hard Townes in a 1961 paper published in the journal Nature titled "Interstellar and Interplanetary Communication by Optical Masers". However, the 1971 Cyclops study discounted the possibility of optical SETI, reasoning that construction of a laser system that could outshine the bright central star of a remote star system would be too difficult. In 1983, Townes published a detailed study of the idea in the United States journal Proceedings of the National Academy of Sciences, which was met with interest by the SETI community.
There are two problems with optical SETI. The first problem is that lasers are highly "monochromatic", that is, they emit light only on one frequency, making it troublesome to figure out what frequency to look for. However, emitting light in narrow pulses results in a broad spectrum of emission; the spread in frequency becomes higher as the pulse width becomes narrower, making it easier to detect an emission.
The other problem is that while radio transmissions can be broadcast in all directions, lasers are highly directional. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from greater distances, but the extraterrestrial laser signals would need to be transmitted in the direction of Earth in order to be detected.
Optical SETI supporters have conducted paper studies of the effectiveness of using contemporary high-energy lasers and a ten-meter diameter mirror as an interstellar beacon. The analysis shows that an infrared pulse from a laser, focused into a narrow beam by such a mirror, would appear thousands of times brighter than the Sun to a distant civilization in the beam's line of fire. The Cyclops study proved incorrect in suggesting a laser beam would be inherently hard to see.
Such a system could be made to automatically steer itself through a target list, sending a pulse to each target at a constant rate. This would allow targeting of all Sun-like stars within a distance of 100 light-years. The studies have also described an automatic laser pulse detector system with a low-cost, two-meter mirror made of carbon composite materials, focusing on an array of light detectors. This automatic detector system could perform sky surveys to detect laser flashes from civilizations attempting contact.
Several optical SETI experiments are now in progress. A Harvard-Smithsonian group that includes Paul Horowitz designed a laser detector and mounted it on Harvard's optical telescope. This telescope is currently being used for a more conventional star survey, and the optical SETI survey is "piggybacking" on that effort. Between October 1998 and November 1999, the survey inspected about 2,500 stars. Nothing that resembled an intentional laser signal was detected, but efforts continue. The Harvard-Smithsonian group is now working with Princeton University to mount a similar detector system on Princeton's 91-centimeter (36-inch) telescope. The Harvard and Princeton telescopes will be "ganged" to track the same targets at the same time, with the intent being to detect the same signal in both locations as a means of reducing errors from detector noise.
The Harvard-Smithsonian SETI group led by Professor Paul Horowitz built a dedicated all-sky optical survey system along the lines of that described above, featuring a 1.8-meter (72-inch) telescope. The new optical SETI survey telescope is being set up at the Oak Ridge Observatory in Harvard, Massachusetts.
The University of California, Berkeley, home of SERENDIP and SETI@home, is also conducting optical SETI searches and collaborates with the NIROSETI program. The optical SETI program at Breakthrough Listen was initially directed by Geoffrey Marcy, an extrasolar planet hunter, and it involves examination of records of spectra taken during extrasolar planet hunts for a continuous, rather than pulsed, laser signal. This survey uses the Automated Planet Finder 2.4-m telescope at the Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California. The other Berkeley optical SETI effort is being pursued by the Harvard-Smithsonian group and is being directed by Dan Werthimer of Berkeley, who built the laser detector for the Harvard-Smithsonian group. This survey uses a 76-centimeter (30-inch) automated telescope at Leuschner Observatory and an older laser detector built by Werthimer.
The SETI Institute also runs a program called 'Laser SETI' with an instrument composed of several cameras that continuously survey the entire night sky searching for millisecond singleton laser pulses of extraterrestrial origin.
In January 2020, two Pulsed All-sky Near-infrared Optical SETI (PANOSETI) project telescopes were installed in the Lick Observatory Astrograph Dome. The project aims to commence a wide-field optical SETI search and continue prototyping designs for a full observatory. The installation can offer an "all-observable-sky" optical and wide-field near-infrared pulsed technosignature and astrophysical transient search for the northern hemisphere.
In May 2017, astronomers reported studies related to laser light emissions from stars, as a way of detecting technology-related signals from an alien civilization. The reported studies included Tabby's Star (designated KIC 8462852 in the Kepler Input Catalog), an oddly dimming star in which its unusual starlight fluctuations may be the result of interference by an artificial megastructure, such as a Dyson swarm, made by such a civilization. No evidence was found for technology-related signals from KIC 8462852 in the studies.
Quantum communications
In a 2021 preprint, astronomer Michael Hipke described for the first time how one could search for quantum communication transmissions sent by ETI using existing telescope and receiver technology. He also provides arguments for why future searches of ETI should also target interstellar quantum communication networks.
A 2022 paper by Arjun Berera and Jaime Calderón-Figueroa noted that interstellar quantum communication by other civilizations could be possible and may be advantageous, identifying some potential challenges and factors for detecting technosignatures. They may, for example, use X-ray photons for remotely established quantum communication and quantum teleportation as the communication mode.
Search for extraterrestrial artifacts
The possibility of using interstellar messenger probes in the search for extraterrestrial intelligence was first suggested by Ronald N. Bracewell in 1960 (see Bracewell probe), and the technical feasibility of this approach was demonstrated by the British Interplanetary Society's starship study Project Daedalus in 1978. Starting in 1979, Robert Freitas advanced arguments for the proposition that physical space-probes are a superior mode of interstellar communication to radio signals (see Voyager Golden Record).
In recognition that any sufficiently advanced interstellar probe in the vicinity of Earth could easily monitor the terrestrial Internet, 'Invitation to ETI' was established by Allen Tough in 1996, as a Web-based SETI experiment inviting such spacefaring probes to establish contact with humanity. The project's 100 signatories includes prominent physical, biological, and social scientists, as well as artists, educators, entertainers, philosophers and futurists. H. Paul Shuch, executive director emeritus of The SETI League, serves as the project's Principal Investigator.
Inscribing a message in matter and transporting it to an interstellar destination can be enormously more energy efficient than communication using electromagnetic waves if delays larger than light transit time can be tolerated. That said, for simple messages such as "hello," radio SETI could be far more efficient. If energy requirement is used as a proxy for technical difficulty, then a solarcentric Search for Extraterrestrial Artifacts (SETA) may be a useful supplement to traditional radio or optical searches.
Much like the "preferred frequency" concept in SETI radio beacon theory, the Earth-Moon or Sun-Earth libration orbits might therefore constitute the most universally convenient parking places for automated extraterrestrial spacecraft exploring arbitrary stellar systems. A viable long-term SETI program may be founded upon a search for these objects.
In 1979, Freitas and Valdes conducted a photographic search of the vicinity of the Earth-Moon triangular libration points and , and of the solar-synchronized positions in the associated halo orbits, seeking possible orbiting extraterrestrial interstellar probes, but found nothing to a detection limit of about 14th magnitude. The authors conducted a second, more comprehensive photographic search for probes in 1982 that examined the five Earth-Moon Lagrangian positions and included the solar-synchronized positions in the stable L4/L5 libration orbits, the potentially stable nonplanar orbits near L1/L2, Earth-Moon , and also in the Sun-Earth system. Again no extraterrestrial probes were found to limiting magnitudes of 17–19th magnitude near L3/L4/L5, 10–18th magnitude for /, and 14–16th magnitude for Sun-Earth .
In June 1983, Valdes and Freitas used the 26 m radiotelescope at Hat Creek Radio Observatory to search for the tritium hyperfine line at 1516 MHz from 108 assorted astronomical objects, with emphasis on 53 nearby stars including all visible stars within a 20 light-year radius. The tritium frequency was deemed highly attractive for SETI work because (1) the isotope is cosmically rare, (2) the tritium hyperfine line is centered in the SETI water hole region of the terrestrial microwave window, and (3) in addition to beacon signals, tritium hyperfine emission may occur as a byproduct of extensive nuclear fusion energy production by extraterrestrial civilizations. The wideband- and narrowband-channel observations achieved sensitivities of 5–14 W/m2/channel and 0.7–2 W/m2/channel, respectively, but no detections were made.
Others have speculated, that we might find traces of past civilizations in our very own Solar System, on planets like Venus or Mars, although the traces would be found most likely underground.
Technosignatures
Technosignatures, including all signs of technology, are a recent avenue in the search for extraterrestrial intelligence. Technosignatures may originate from various sources, from megastructures such as Dyson spheres and space mirrors or space shaders to the atmospheric contamination created by an industrial civilization, or city lights on extrasolar planets, and may be detectable in the future with large hypertelescopes.
Technosignatures can be divided into three broad categories: astroengineering projects, signals of planetary origin, and spacecraft within and outside the Solar System.
An astroengineering installation such as a Dyson sphere, designed to convert all of the incident radiation of its host star into energy, could be detected through the observation of an infrared excess from a solar analog star, or by the star's apparent disappearance in the visible spectrum over several years. After examining some 100,000 nearby large galaxies, a team of researchers has concluded that none of them display any obvious signs of highly advanced technological civilizations.
Another hypothetical form of astroengineering, the Shkadov thruster, moves its host star by reflecting some of the star's light back on itself, and would be detected by observing if its transits across the star abruptly end with the thruster in front. Asteroid mining within the Solar System is also a detectable technosignature of the first kind.
Individual extrasolar planets can be analyzed for signs of technology. Avi Loeb of the Center for Astrophysics Harvard & Smithsonian has proposed that persistent light signals on the night side of an exoplanet can be an indication of the presence of cities and an advanced civilization. In addition, the excess infrared radiation and chemicals produced by various industrial processes or terraforming efforts may point to intelligence.
Light and heat detected from planets need to be distinguished from natural sources to conclusively prove the existence of civilization on a planet. However, as argued by the Colossus team, a civilization heat signature should be within a "comfortable" temperature range, like terrestrial urban heat islands, i.e., only a few degrees warmer than the planet itself. In contrast, such natural sources as wild fires, volcanoes, etc. are significantly hotter, so they will be well distinguished by their maximum flux at a different wavelength.
Other than astroengineering, technosignatures such as artificial satellites around exoplanets, particularly such in geostationary orbit, might be detectable even with today's technology and data, and would allow, similar to fossils on Earth, to find traces of extrasolar life from long ago.
Extraterrestrial craft are another target in the search for technosignatures. Magnetic sail interstellar spacecraft should be detectable over thousands of light-years of distance through the synchrotron radiation they would produce through interaction with the interstellar medium; other interstellar spacecraft designs may be detectable at more modest distances. In addition, robotic probes within the Solar System are also being sought with optical and radio searches.
For a sufficiently advanced civilization, hyper energetic neutrinos from Planck scale accelerators should be detectable at a distance of many Mpc.
Advances for Bio and Technosignature Detection
A notable advancement in technosignature detection is the development of an algorithm for signal reconstruction in zero-knowledge one-way communication channels. This algorithm decodes signals from unknown sources without prior knowledge of the encoding scheme, using principles from Algorithmic Information Theory to identify the geometric and topological dimensions of the encoding space. It successfully reconstructed the Arecibo message despite significant noise. The work establishes a connection between syntax and semantics in SETI and technosignature detection, enhancing fields like cryptography and Information Theory.
Based on fractal theory and the Weierstrass function, a known fractal, another method authored by the same group called fractal messaging offers a framework for space-time scale-free communication. This method leverages properties of self-similarity and scale invariance, enabling spatio-temporal scale-independent and parallel infinite-frequency communication. It also embodies the concept of sending a self-encoding/self-decoding signal as a mathematical formula, equivalent to self-executable computer code that unfolds to read a message at all possible time scales and in all possible channels simultaneously.
Fermi paradox
Italian physicist Enrico Fermi suggested in the 1950s that if technologically advanced civilizations are common in the universe, then they should be detectable in one way or another. According to those who were there, Fermi either asked "Where are they?" or "Where is everybody?"
The Fermi paradox is commonly understood as asking why extraterrestrials have not visited Earth, but the same reasoning applies to the question of why signals from extraterrestrials have not been heard. The SETI version of the question is sometimes referred to as "the Great Silence".
The Fermi paradox can be stated more completely as follows:
There are multiple explanations proposed for the Fermi paradox, ranging from analyses suggesting that intelligent life is rare (the "Rare Earth hypothesis"), to analyses suggesting that although extraterrestrial civilizations may be common, they would not communicate with us, would communicate in a way we have not discovered yet, could not travel across interstellar distances, or destroy themselves before they master the technology of either interstellar travel or communication.
The German astrophysicist and radio astronomer Sebastian von Hoerner suggested that the average duration of civilization was 6,500 years. After this time, according to him, it disappears for external reasons (the destruction of life on the planet, the destruction of only rational beings) or internal causes (mental or physical degeneration). According to his calculations, on a habitable planet (one in three million stars) there is a sequence of technological species over a time distance of hundreds of millions of years, and each of them "produces" an average of four technological species. With these assumptions, the average distance between civilizations in the Milky Way is 1,000 light years.
Science writer Timothy Ferris has posited that since galactic societies are most likely only transitory, an obvious solution is an interstellar communications network, or a type of library consisting mostly of automated systems. They would store the cumulative knowledge of vanished civilizations and communicate that knowledge through the galaxy. Ferris calls this the "Interstellar Internet", with the various automated systems acting as network "servers". If such an Interstellar Internet exists, the hypothesis states, communications between servers are mostly through narrow-band, highly directional radio or laser links. Intercepting such signals is, as discussed earlier, very difficult. However, the network could maintain some broadcast nodes in hopes of making contact with new civilizations.
Although somewhat dated in terms of "information culture" arguments, not to mention the obvious technological problems of a system that could work effectively for billions of years and requires multiple lifeforms agreeing on certain basics of communications technologies, this hypothesis is actually testable (see below).
Difficulty of detection
A significant problem is the vastness of space. Despite piggybacking on the world's most sensitive radio telescope, astronomer and initiator of SERENDIP Charles Stuart Bowyer noted the then world's largest instrument could not detect random radio noise emanating from a civilization like ours, which has been leaking radio and TV signals for less than 100 years. For SERENDIP and most other SETI projects to detect a signal from an extraterrestrial civilization, the civilization would have to be beaming a powerful signal directly at us. It also means that Earth civilization will only be detectable within a distance of 100 light-years.
Post-detection disclosure protocol
The International Academy of Astronautics (IAA) has a long-standing SETI Permanent Study Group (SPSG, formerly called the IAA SETI Committee), which addresses matters of SETI science, technology, and international policy. The SPSG meets in conjunction with the International Astronautical Congress (IAC), held annually at different locations around the world, and sponsors two SETI Symposia at each IAC. In 2005, the IAA established the SETI: Post-Detection Science and Technology Taskgroup (chairman, Professor Paul Davies) "to act as a Standing Committee to be available to be called on at any time to advise and consult on questions stemming from the discovery of a putative signal of extraterrestrial intelligent (ETI) origin."
However, the protocols mentioned apply only to radio SETI rather than for METI (Active SETI). The intention for METI is covered under the SETI charter "Declaration of Principles Concerning Sending Communications with Extraterrestrial Intelligence".
In October 2000 astronomers Iván Almár and Jill Tarter presented a paper to The SETI Permanent Study Group in Rio de Janeiro, Brazil which proposed a scale (modelled after the Torino scale) which is an ordinal scale between zero and ten that quantifies the impact of any public announcement regarding evidence of extraterrestrial intelligence; the Rio scale has since inspired the 2005 San Marino Scale (in regard to the risks of transmissions from Earth) and the 2010 London Scale (in regard to the detection of extraterrestrial life). The Rio scale itself was revised in 2018.
The SETI Institute does not officially recognize the Wow! signal as of extraterrestrial origin as it was unable to be verified, although in a 2020 tweet the organization stated that ''an astronomer might have pinpointed the host star''. The SETI Institute has also publicly denied that the candidate signal Radio source SHGb02+14a is of extraterrestrial origin. Although other volunteering projects such as Zooniverse credit users for discoveries, there is currently no crediting or early notification by SETI@Home following the discovery of a signal.
Some people, including Steven M. Greer, have expressed cynicism that the general public might not be informed in the event of a genuine discovery of extraterrestrial intelligence due to significant vested interests. Some, such as Bruce Jakosky have also argued that the official disclosure of extraterrestrial life may have far reaching and as yet undetermined implications for society, particularly for the world's religions.
Active SETI
Active SETI, also known as messaging to extraterrestrial intelligence (METI), consists of sending signals into space in the hope that they will be detected by an alien intelligence.
Realized interstellar radio message projects
In November 1974, a largely symbolic attempt was made at the Arecibo Observatory to send a message to other worlds. Known as the Arecibo Message, it was sent towards the globular cluster M13, which is 25,000 light-years from Earth. Further IRMs Cosmic Call, Teen Age Message, Cosmic Call 2, and A Message From Earth were transmitted in 1999, 2001, 2003 and 2008 from the Evpatoria Planetary Radar.
Debate
Whether or not to attempt to contact extraterrestrials has attracted significant academic debate in the fields of space ethics and space policy. Physicist Stephen Hawking, in his book A Brief History of Time, suggests that "alerting" extraterrestrial intelligences to our existence is foolhardy, citing humankind's history of treating its own kind harshly in meetings of civilizations with a significant technology gap, e.g., the extermination of Tasmanian aborigines. He suggests, in view of this history, that we "lay low". In one response to Hawking, in September 2016, astronomer Seth Shostak sought to allay such concerns. Astronomer Jill Tarter also disagrees with Hawking, arguing that aliens developed and long-lived enough to communicate and travel across interstellar distances would have evolved a cooperative and less violent intelligence. She however thinks it is too soon for humans to attempt active SETI and that humans should be more advanced technologically first but keep listening in the meantime.
Criticism
As various SETI projects have progressed, some have criticized early claims by researchers as being too "euphoric". For example, Peter Schenkel, while remaining a supporter of SETI projects, wrote in 2006 that:
Critics claim that the existence of extraterrestrial intelligence has no good Popperian criteria for falsifiability, as explained in a 2009 editorial in Nature, which said:
Nature added that SETI was "marked by a hope, bordering on faith" that aliens were aiming signals at us, that a hypothetical alien SETI project looking at Earth with "similar faith" would be "sorely disappointed", despite our many untargeted radar and TV signals, and our few targeted Active SETI radio signals denounced by those fearing aliens, and that it had difficulties attracting even sympathetic working scientists and government funding because it was "an effort so likely to turn up nothing".
However, Nature also added, "Nonetheless, a small SETI effort is well worth supporting, especially given the enormous implications if it did succeed" and that "happily, a handful of wealthy technologists and other private donors have proved willing to provide that support".
Supporters of the Rare Earth Hypothesis argue that advanced lifeforms are likely to be very rare, and that, if that is so, then SETI efforts will be futile. However, the Rare Earth Hypothesis itself faces many criticisms.
In 1993, Roy Mash stated that "Arguments favoring the existence of extraterrestrial intelligence nearly always contain an overt appeal to big numbers, often combined with a covert reliance on generalization from a single instance" and concluded that "the dispute between believers and skeptics is seen to boil down to a conflict of intuitions which can barely be engaged, let alone resolved, given our present state of knowledge". In response, in 2012, Milan M. Ćirković, then research professor at the Astronomical Observatory of Belgrade and a research associate of the Future of Humanity Institute at the University of Oxford, said that Mash was unrealistically over-reliant on excessive abstraction that ignored the empirical information available to modern SETI researchers.
George Basalla, Emeritus Professor of History at the University of Delaware, is a critic of SETI who argued in 2006 that "extraterrestrials discussed by scientists are as imaginary as the spirits and gods of religion or myth", and was in turn criticized by Milan M. Ćirković for, among other things, being unable to distinguish between "SETI believers" and "scientists engaged in SETI", who are often sceptical (especially about quick detection), such as Freeman Dyson and, at least in their later years, Iosif Shklovsky and Sebastian von Hoerner, and for ignoring the difference between the knowledge underlying the arguments of modern scientists and those of ancient Greek thinkers.
Massimo Pigliucci, Professor of Philosophy at CUNY – City College, asked in 2010 whether SETI is "uncomfortably close to the status of pseudoscience" due to the lack of any clear point at which negative results cause the hypothesis of Extraterrestrial Intelligence to be abandoned, before eventually concluding that SETI is "almost-science", which is described by Milan M. Ćirković as Pigliucci putting SETI in "the illustrious company of string theory, interpretations of quantum mechanics, evolutionary psychology and history (of the 'synthetic' kind done recently by Jared Diamond)", while adding that his justification for doing so with SETI "is weak, outdated, and reflecting particular philosophical prejudices similar to the ones described above in Mash and Basalla".
Richard Carrigan, a particle physicist at the Fermi National Accelerator Laboratory near Chicago, Illinois, suggested that passive SETI could also be dangerous and that a signal released onto the Internet could act as a computer virus. Computer security expert Bruce Schneier dismissed this possibility as a "bizarre movie-plot threat".
Ufology
Ufologist Stanton Friedman has often criticized SETI researchers for, among other reasons, what he sees as their unscientific criticisms of Ufology, but, unlike SETI, Ufology has generally not been embraced by academia as a scientific field of study, and it is usually characterized as a partial or total pseudoscience. In a 2016 interview, Jill Tarter pointed out that it is still a misconception that SETI and UFOs are related. She states, "SETI uses the tools of the astronomer to attempt to find evidence of somebody else's technology coming from a great distance. If we ever claim detection of a signal, we will provide evidence and data that can be independently confirmed. UFOs—none of the above." The Galileo Project headed by Harvard astronomer Avi Loeb is one of the few scientific efforts to study UFOs or UAPs. Loeb criticized that the study of UAP is often dismissed and not sufficiently studied by scientists and should shift from "occupying the talking points of national security administrators and politicians" to the realm of science. The Galileo Project's position after the publication of the 2021 UFO Report by the U.S. Intelligence community is that the scientific community needs to "systematically, scientifically and transparently look for potential evidence of extraterrestrial technological equipment".
See also
a suggested mission involving a constellation of spacecraft to directly detect Earth-like planets
– e.g. detectability to SETI programs by extraterrestrials
Hypothetical life forms inside stars
Open SETI on the Allen Telescope Array
potential SETI signal
References
Further reading
Phillip Morrison, John Billingham, & John Wolfe: The search for extraterrestrial intelligence—SETI. NASA SP, Washington 1977
David W. Swift: Seti Pioneers: Scientists Talk about Their Search for Extraterrestrial Intelligence. University of Arizona Press, Tucson, Arizona, 1993,
Frank White: The Seti Factor: How the Search for Extraterrestrial Intelligence Is Changing Our View of the Universe and Ourselves. Walker & Company, New York 1990,
External links
SETI official website
Harvard University SETI Program
University of California, Berkeley SETI Program
Project Dorothy, a Worldwide Joint SETI Observation to Commemorate the 50th Anniversary of Project OZMA
The Rio Scale , a scale for rating SETI announcements
2012 Interview of SETI Pioneer Frank Drake by astronomer Andrew Fraknoi
Now dark SETI Net station archives (www.seti.net)
Astrobiology
Distributed computing projects
Radio astronomy
Interstellar messages | Search for extraterrestrial intelligence | Astronomy,Engineering,Biology | 11,042 |
26,946,683 | https://en.wikipedia.org/wiki/Termite-flg%20RNA%20motif | The Termite-flg RNA motif (also called tg-flg) is a conserved RNA structure identified by bioinformatics. Genomic sequences corresponding to Termite-flg RNAs have been identified only in uncultivated bacteria present in the termite hindgut. As of 2010 it has not been identified in the DNA of any cultivated species, and is thus an example of RNAs present in environmental samples.
Termite-flg RNAs are consistently located in what is presumed to be the 5' untranslated regions of genes that encode proteins whose functions relate to flagella. The RNAs are hypothesized to regulate these genes in an unknown mechanism.
References
External links
Cis-regulatory RNA elements | Termite-flg RNA motif | Chemistry | 153 |
11,090,023 | https://en.wikipedia.org/wiki/Tinguiririca%20fauna | The fossil Tinguiririca fauna, entombed in volcanic mudflows and ash layers at the onset of the Oligocene, about 33-31.5 million years ago, represents a unique snapshot of the history of South America's endemic fauna, which was extinguished when the former island continent was joined to North America by the rising Isthmus of Panama. The fossil-bearing sedimentary layers of the Abanico Formation were first discovered in the valley of the Tinguiririca River, high in the Andes of central Chile. The faunal assemblage lends its name to the Tinguirirican stage in the South American land mammal age (SALMA) classification.
Description
The endemic fauna bridges a massive gap in the history of those mammals that were unique to South America. Paleontologists knew the earlier sloth and anteater forebears of 40 mya, but no fossils from this previously poorly sampled transitional age had been seen. Fossils of the Tinguiririca fauna include the chinchilla-like earliest rodents discovered in South America, a wide range of the hoofed herbivores called notoungulates, a shrew-like marsupial and ancestors of today's sloth and armadillos. Many of the herbivores have teeth adapted to grass-eating; though no plant fossils have been recovered, the high-crowned hypsodont teeth, protected by tough enamel well below the gumline, identifies grazers suited to a gritty diet. "The proportion of hypsodont taxa relative to other dental types generally increases with the amount of open habitat," John Flynn explained in Scientific American (May 2007) "and the Tinguiririca level of hysodonty surpasses even that observed for mammals living in modern, open habitats such as the Great Plains of North America." Statistical analyses of the number of species categorized by body size ("cenogram" analysis, an aspect of body size scaling) and of their broad ecological niches ("macroniche" analysis) bears out the existence of dry grasslands. Previously, no grassland ecosystem anywhere had been identified prior to Miocene systems fifteen million years later than the Tinguiririca fauna. Grasslands spread as the Earth's paleoclimate grew cooler and drier.
New fossils were uncovered of the New World monkeys and caviomorph rodents— the group that includes the capybara— which are known not to have evolved in situ. Some of the new fossils demonstrate by the form of their teeth that they lie closer to African fossil relatives than to the North American ones, which previously had been assumed to have rafted to the island continent. Now it appears that some may have made the crossing of a younger, much narrower Atlantic Ocean. A notable discovery was the miniature skull of a delicate progenitor of New World marmosets and tamarins; it has been given the name Chilecebus carrascoensis.
The first of the fossils were found in 1988. Since then, in strata representing repeated catastrophic lahar events, more than 1500 individual fossils have been recovered from multiple sites in the region, ranging in age from 40 to 10 mya. The mammal species Archaeotypotherium tinguiriricaense is named after the site.
See also
South American land mammal age - list of fossils from this age and site
References
Further reading
Flynn, John J., André R. Wyss, and Reynaldo Charrier, "South America's missing mammals", Scientific American (May 2007) pp 68–75. The article is the source of the present summary. (on-line text).
Simpson, George Gaylord, Splendid Isolation: The Curious History of South American Mammals (Yale University Press) 1980. The previous status quo in this field.
External links
Mammal lineages of island South America
John J. Flynn, André R. Wyss, Darin A. Croft and Reynaldo Charrier, "The Tinguiririca fauna, Chile: biochronology, paleoecology, biogeography and a new earliest Oligocene South American Land Mammal 'Age'" (abstract: pdf file)
D. A. Croft, "New species" including several from the Tinguiririca fauna
.
Eocene South America
Oligocene South America
Cenozoic animals of South America
Paleogene Chile
Paleontology in Chile
Biogeography
Prehistoric fauna by locality
Cenozoic paleobiotas | Tinguiririca fauna | Biology | 921 |
14,350,883 | https://en.wikipedia.org/wiki/Brown%20Dog%20affair | The Brown Dog affair was a political controversy about vivisection that raged in Britain from 1903 until 1910. It involved the infiltration of University of London medical lectures by Swedish feminists, battles between medical students and the police, police protection for the statue of a dog, a libel trial at the Royal Courts of Justice, and the establishment of a Royal Commission to investigate the use of animals in experiments. The affair became a that divided the country.
The controversy was triggered by allegations that, in February 1903, William Bayliss of the Department of Physiology at University College London performed an illegal vivisection, before an audience of 60 medical students, on a brown terrier dog—adequately anaesthetised, according to Bayliss and his team; conscious and struggling, according to the Swedish activists. The procedure was condemned as cruel and unlawful by the National Anti-Vivisection Society. Outraged by the assault on his reputation, Bayliss, whose research on dogs led to the discovery of hormones, sued for libel and won.
Anti-vivisectionists commissioned a bronze statue of the dog as a memorial, unveiled on the Latchmere Recreation Ground in Battersea in 1906, but medical students were angered by its provocative plaque—"Men and women of England, how long shall these Things be?"—leading to frequent vandalism of the memorial and the need for a 24-hour police guard against the so-called anti-doggers. On 10 December 1907, hundreds of medical students marched through central London waving effigies of the brown dog on sticks, clashing with suffragettes, trade unionists and 300 police officers, one of a series of battles known as the Brown Dog riots.
In March 1910, tired of the controversy, Battersea Council sent four workers accompanied by 120 police officers to remove the statue under cover of darkness, after which it was reportedly melted down by the council's blacksmith, despite a 20,000-strong petition in its favour. A new statue of the brown dog, commissioned by anti-vivisection groups, was erected in Battersea Park in 1985. On 6 September 2021, the 115th anniversary of when the original statue was unveiled, a new campaign was launched by the author Paula S. Owen to recast the original statue.
Background
Cruelty to Animals Act 1876
There was significant opposition to vivisection in England, in both houses of Parliament, during the reign of Queen Victoria (1837–1901); the Queen herself strongly opposed it. The term vivisection referred to the dissection of living animals, with and without anaesthesia, often in front of audiences of medical students. In 1878 there were under 300 experiments on animals in the UK, a figure that had risen to 19,084 in 1903 when the brown dog was vivisected (according to the inscription on the second Brown Dog statue), and to five million by 1970.
Physiologists in the 19th century were frequently criticised for their work. The prominent French physiologist Claude Bernard appears to have shared the distaste of his critics, who included his wife, referring to "the science of life" as a "superb and dazzlingly lighted hall which may be reached only by passing through a long and ghastly kitchen". In 1875, Irish feminist Frances Power Cobbe founded the National Anti-Vivisection Society (NAVS) in London and in 1898 the British Union for the Abolition of Vivisection (BUAV). The former sought to restrict vivisection and the latter to abolish it.
The opposition led the British government, in July 1875, to set up the first Royal Commission on the "Practice of Subjecting Live Animals to Experiments for Scientific Purposes". After hearing that researchers did not use anaesthesia regularly—one scientist, Emmanuel Klein told the commission he had "no regard at all" for the suffering of the animals—the commission recommended a series of measures, including a ban on experiments on dogs, cats, horses, donkeys and mules. The General Medical Council and British Medical Journal objected, so additional protection was introduced instead. The result was the Cruelty to Animals Act 1876, criticised by NAVS as "infamous but well-named".
The act stipulated that researchers could not be prosecuted for cruelty, but that the animal must be anaesthetised, unless the anaesthesia would interfere with the point of the experiment. Each animal could be used only once, although several procedures regarded as part of the same experiment were permitted. The animal had to be killed when the study was over, unless doing so would frustrate the object of the experiment. Prosecutions could take place only with the approval of the home secretary. At the time of the Brown Dog affair, this was Aretas Akers-Douglas, who was unsympathetic to the anti-vivisectionist cause.
Ernest Starling and William Bayliss
In the early 20th century, Ernest Starling, professor of physiology at University College London, and his brother-in-law William Bayliss, were using vivisection on dogs to determine whether the nervous system controls pancreatic secretions, as postulated by Ivan Pavlov. Bayliss had held a licence to practice vivisection since 1890 and had taught physiology since 1900. According to Starling's biographer John Henderson, Starling and Bayliss were "compulsive experimenters", and Starling's lab was the busiest in London.
The men knew that the pancreas produces digestive juices in response to increased acidity in the duodenum and jejunum, because of the arrival of chyme there. By severing the duodenal and jejunal nerves in anaesthetised dogs, while leaving the blood vessels intact, then introducing acid into the duodenum and jejunum, they discovered that the process is not mediated by a nervous response, but by a new type of chemical reflex. They named the chemical messenger secretin, because it is secreted by the intestinal lining into the bloodstream, stimulating the pancreas on circulation. In 1905 Starling coined the term hormone—from the Greek hormao meaning "I arouse" or "I excite"—to describe chemicals such as secretin that are capable, in extremely small quantities, of stimulating organs from a distance.
Bayliss and Starling had also used vivisection on anaesthetised dogs to discover peristalsis in 1899. They went on to discover a variety of other important physiological phenomena and principles, many of which were based on their experimental work involving animal vivisection.
Lizzy Lind af Hageby and Leisa Schartau
Starling and Bayliss's lectures had been infiltrated by two Swedish feminists and anti-vivisection activists, Lizzy Lind af Hageby and Leisa Schartau. The women had known each other since childhood and came from distinguished families; Lind af Hageby, who had attended Cheltenham Ladies College, was the granddaughter of a chamberlain to the king of Sweden.
In 1900, the women visited the Pasteur Institute in Paris, a centre of animal experimentation, and were shocked by the rooms full of caged animals given diseases by the researchers. When they returned home, they founded the Anti-Vivisection Society of Sweden, and to gain medical training to help their campaigning, they enrolled in 1902 at the London School of Medicine for Women, a vivisection-free college that had visiting arrangements with other colleges. They attended 100 lectures and demonstrations at King's and University College, including 50 experiments on live animals, of which 20 were what Mason called "full-scale vivisection". Their diary, at first called Eye-Witnesses, was later published as The Shambles of Science: Extracts from the Diary of Two Students of Physiology (1903); shambles was a name for a slaughterhouse. The women were present when the brown dog was vivisected, and wrote a chapter about it entitled "Fun", referring to the laughter they said they heard in the lecture room during the procedure.
The following year, a revised edition was published without that chapter; the authors wrote: "The story of the thrice vivisected brown dog as told by its vivisectors to the Lord Chief Justice and a special jury, and as it is found in the verbatim report of the trial, proved the true nature of vivisection far better than the chapter 'Fun' which can now be dispensed with."
The brown dog
Vivisection of the dog
According to Starling, the brown dog was "a small brown mongrel allied to a terrier with short roughish hair, about 14–15 lb [c. 6 kg] in weight". He was first used in a vivisection in December 1902 by Starling, who cut open his abdomen and ligated the pancreatic duct. For the next two months he lived in a cage, until Starling and Bayliss used him again for two procedures on 2 February 1903, the day the Swedish women were present.
Outside the lecture room before the students arrived, according to testimony Starling and others gave in court, Starling cut the dog open again to inspect the results of the previous surgery, which took about 45 minutes, after which he clamped the wound with forceps and handed the dog over to Bayliss. Bayliss cut a new opening in the dog's neck to expose the lingual nerves of the salivary glands, to which he attached electrodes. The aim was to stimulate the nerves with electricity to demonstrate that salivary pressure was independent of blood pressure. The dog was then carried to the lecture theatre, stretched on his back on an operating board, with his legs tied to the board, his head clamped and his mouth muzzled.
According to Bayliss, the dog had been given a morphine injection earlier in the day, then was anaesthetised during the procedure with six fluid ounces of alcohol, chloroform and ether (ACE), delivered from an ante-room to a tube in his trachea, via a pipe hidden behind the bench on which the men were working. The Swedish students disputed that the dog had been adequately anaesthetised. They said the dog had appeared conscious during the procedure, had tried to lift himself off the board, and that there was no smell of anaesthesia or the usual hissing sound of the apparatus. Other students said the dog had not struggled, but had merely twitched.
In front of around 60 students, Bayliss stimulated the nerves with electricity for half an hour, but was unable to demonstrate his point. The dog was then handed to a student, Henry Dale, a future Nobel laureate, who removed the dog's pancreas, then killed him with a knife through the heart. This became a point of embarrassment during the libel trial, when Bayliss's laboratory assistant, Charles Scuttle, testified that the dog had been killed with chloroform or the ACE mixture. After Scuttle's testimony, Dale told the court that he had, in fact, used a knife.
Women's diary
On 14 April 1903, Lind af Hageby and Schartau showed their unpublished 200-page diary, published later that year as The Shambles of Science, to the barrister Stephen Coleridge, secretary of the National Anti-Vivisection Society. Coleridge was the son of John Duke Coleridge, former Lord Chief Justice of England, and great-grandson of the poet Samuel Taylor Coleridge. His attention was drawn to the account of the brown dog. The 1876 Cruelty to Animals Act forbade the use of an animal in more than one experiment, yet it appeared that the brown dog had been used by Starling to perform surgery on the pancreas, used again by him when he opened the dog to inspect the results of the previous surgery, and used for a third time by Bayliss to study the salivary glands. The diary said of the procedures on the brown dog:
Today's lecture will include a repetition of a demonstration which failed last time. A large dog, stretched on its back on an operation board, is carried into the lecture-room by the demonstrator and the laboratory attendant. Its legs are fixed to the board, its head is firmly held in the usual manner, and it is tightly muzzled.
There is a large incision in the side of the neck, exposing the gland. The animal exhibits all signs of intense suffering; in his struggles, he again and again lifts his body from the board, and makes powerful attempts to get free.
The allegations of repeated use and inadequate anaesthesia represented prima facie violations of the Cruelty to Animals Act. In addition the diary said the dog had been killed by Henry Dale, an unlicensed research student, and that the students had laughed during the procedure; there were "jokes and laughter everywhere" in the lecture hall, it said.
Coleridge's speech
According to Mason, Coleridge decided there was no point in relying on a prosecution under the act, which he regarded as deliberately obstructive. Instead he gave an angry speech about the dog on 1 May 1903 to the annual meeting of the National Anti-Vivisection Society at St James's Hall in Piccadilly, attended by 2,000–3,000 people. Mason writes that support and apologies for absence were sent by Jerome K. Jerome, Thomas Hardy and Rudyard Kipling. Coleridge accused the scientists of torture: "If this is not torture, let Mr. Bayliss and his friends ... tell us in Heaven's name what torture is."
Details of the speech were published the next day by the radical Daily News (founded in 1846 by Charles Dickens), and questions were raised in the House of Commons, particularly by Sir Frederick Banbury, a Conservative MP and sponsor of a bill aimed at ending vivisection demonstrations. Banbury asked the Home Secretary to state "under what certificate the operation on a brown dog was performed at University College Hospital on Feb. 2 last; and, whether, seeing that a second operation was performed upon this animal before the wounds caused by the first operation had healed, he proposes to take any action in the matter."
Bayliss demanded a public apology from Coleridge, and, when it had failed to materialise by 12 May, he issued a writ for libel. Ernest Starling decided not to sue; The Lancet, no friend of Coleridge, wrote that "it may be contended that Dr. Starling and Mr. Bayliss committed a technical infringement of the Act under which they performed their experiments." Coleridge tried to persuade the women not to publish their diary before the trial began, but they went ahead anyway, and it was published by Ernest Bell of Covent Garden in July 1903.
Bayliss v. Coleridge
Trial
The trial opened at the Old Bailey on 11 November 1903 before Lord Alverstone, the Lord Chief Justice, and lasted four days, closing on 18 November. There were queues 30 yards long outside the courthouse. Bayliss's barrister, Rufus Isaacs, called Starling as his first witness. Starling admitted that he had broken the law by using the dog twice, but said that he had done so to avoid sacrificing two dogs. Bayliss testified that the dog had been given one-and-a-half grains of morphia earlier in the day, then six ounces of alcohol, chloroform and ether, delivered from an ante room to a tube connected to the dog's trachea. The tubes were fragile, he said, and had the dog been struggling they would have broken.
A veterinarian, Alfred Sewell, said the system Bayliss was using was unlikely to be adequate, but other witnesses, including Frederick Hobday of the Royal Veterinary College, disagreed; there was even a claim that Bayliss had used too much anaesthesia, which is why the dog had failed to respond to the electrical stimulation. According to Bayliss, the dog had been suffering from chorea, a disease that causes involuntary spasm, and that any movement reported by Lind af Hageby and Schartau had not been purposive. Four students, three women and a man, testified that the dog had seemed unconscious.
Coleridge's barrister, John Lawson Walton, called Lind af Hageby and Schartau. They repeated they had been the first students to arrive and had been left alone with the dog for about two minutes. They had observed scars from the previous operations and an incision in the neck where two tubes had been placed. They had not smelled the anaesthetic and had not seen any apparatus delivering it. They said, Mason wrote, that the dog had arched his back and jerked his legs in what they regarded as an effort to escape. When the experiment began the dog continued to "upheave its abdomen" and tremble, they said, movements they regarded as "violent and purposeful".
Bayliss's lawyer criticised Coleridge for having accepted the women's statements without seeking corroboration, and for speaking about the issue publicly without first approaching Bayliss, despite knowing that doing so could lead to litigation. Coleridge replied that he had not sought verification because he knew the claims would be denied, and that he continued to regard the women's statement as true. The Times wrote of his testimony: "The Defendant, when placed in the witness box, did as much damage to his own case as the time at his disposal for the purpose would allow."
Verdict
Lord Alverstone told the jury that the case was an important one of national interest. He called The Shambles of Science "hysterical" and advised the jury not to be swayed by arguments about the validity of vivisection. After retiring for 25 minutes on 18 November 1903, the jury unanimously found that Bayliss had been defamed, to the applause of physicians in the public gallery. Bayliss was awarded £2,000 with £3,000 costs; Coleridge gave him a cheque the next day. The Daily News asked for donations to cover Coleridge's costs and raised £5,700 within four months. Bayliss donated his damages to UCL for use in research; according to Mason, Bayliss ignored the Daily Mails suggestion that he call it the "Stephen Coleridge Vivisection Fund". Gratzer wrote in 2004 that the fund may still have been in use then to buy animals.
The Times declared itself satisfied with the verdict, although it criticised the rowdy behaviour of medical students during the trial, accusing them of "medical hooliganism". The Sun, Star and Daily News backed Coleridge, calling the decision a miscarriage of justice. Ernest Bell, publisher of The Shambles of Science, apologised to Bayliss on 25 November, and pledged to withdraw the diary and pass its remaining copies to Bayliss's solicitors.
The Animal Defence and Anti-Vivisection Society, founded by Lind af Hageby in 1903, republished the book, printing a fifth edition by 1913. The chapter "Fun" was replaced by one called "The Vivisections of the Brown Dog", describing the experiment and the trial. The novelist Thomas Hardy kept a copy of the book on a table for visitors; he told a correspondent that he had "not really read [it], but everybody who comes into this room, where it lies on my table, dips into it, etc, and, I hope, profits something". According to historian Hilda Kean, the Research Defence Society, a lobby group founded in 1908 to counteract the antivivisectionist campaign, discussed how to have the revised editions withdrawn because of the book's impact.
In December 1903, Mark Twain, who opposed vivisection, published a short story, A Dog's Tale, in Harper's, written from the point of view of a dog whose puppy is experimented on and killed. Given the timing and Twain's views, the story may have been inspired by the libel trial, according to Mark Twain scholar Shelley Fisher Fishkin. Coleridge ordered 3,000 copies of A Dog's Tale, which were specially printed for him by Harper's.
Second Royal Commission on Vivisection
On 17 September 1906, the government appointed the Second Royal Commission on Vivisection, which heard evidence from scientists and anti-vivisection groups; Ernest Starling addressed the commission for three days in December 1906. After much delay (two of its ten members died and several fell ill), the commission reported its findings in March 1912. Its 139-page report recommended an increase in the number of full-time inspectors from two to four, and restrictions on the use of curare, a poison used to immobilise animals during experiments. The Commission decided that animals should be adequately anaesthetised, and euthanised if the pain was likely to continue, and experiments should not be performed "as an illustration of lectures" in medical schools and similar. All the restrictions could be lifted if they would "frustrate the object of the experiment". There was also a tightening of the definition and practice of pithing. The Commission recommended the maintenance of more detailed records and the establishment of a committee to advise the Secretary of State on matters related to the Cruelty to Animals Act. The latter became the Animal Procedures Committee under the Animals (Scientific Procedures) Act 1986.
Brown Dog memorial
Original memorial
After the trial Anna Louisa Woodward, founder of the World League Against Vivisection, raised £120 for a public memorial and commissioned a bronze statue of the dog from sculptor Joseph Whitehead. The statue sat on top of a granite memorial stone, 7 ft 6 in (2.29 m) tall, that housed a drinking fountain for human beings and a lower trough for dogs and horses. It also carried an inscription (right), described by The New York Times in 1910 as the "hysterical language customary of anti-vivisectionists" and "a slander on the whole medical profession".
The group turned to the borough of Battersea for a location for the memorial. Lansbury wrote that the area was a hotbed of radicalism—proletarian, socialist, full of belching smoke and slums, and closely associated with the anti-vivisection movement. The National Anti-Vivisection and Battersea General Hospital—opened in 1896, on the corner of Albert Bridge Road and Prince of Wales Drive, and closed in 1972—refused until 1935 to perform vivisection or employ doctors who engaged in it, and was known locally as the "antiviv" or the "old anti". The chairman of the Battersea Dogs Home, William Cavendish-Bentinck, 6th Duke of Portland, rejected a request in 1907 that its lost dogs be sold to vivisectors as "not only horrible, but absurd".
Battersea council agreed to provide space for the statue on its Latchmere Recreation Ground, part of the council's new Latchmere Estate, which offered terraced homes to rent for seven and sixpence a week. The statue was unveiled on 15 September 1906 in front of a large crowd, with speakers that included George Bernard Shaw, the Irish feminist Charlotte Despard, the mayor of Battersea, James H. Brown (secretary of the Battersea Trades and Labour Council), and the Reverend Charles Noel.
Riots
November–December 1907
Medical students at London's teaching hospitals were enraged by the plaque. The first year of the statue's existence was a quiet one, while University College explored whether they could take legal action over it, but from November 1907 the students turned Battersea into the scene of frequent disruption.
The first action was on 20 November, when undergraduate William Howard Lister led a group of medical students across the Thames to Battersea to attack the statue with a crowbar and sledgehammer. One of them, Duncan Jones, hit the statue with a hammer, denting it, at which point all ten were arrested by just two police officers. According to Mason, a local doctor told the South Western Star that this signalled the "utter degeneration" of junior doctors: "I can remember the time when it was more than 10 policemen could do to take one student. The Anglo-Saxon race is played out."
The students were fined £5 by the magistrate, Paul Taylor, at South-West London Police Court in Battersea and warned they would be jailed next time. This triggered another protest two days later, when medical students from UCL, King's, Guy's, and the West Middlesex hospitals marched along the Strand toward King's College, waving miniature brown dogs on sticks and a life-sized effigy of the magistrate, and singing, "Let's hang Paul Taylor on a sour apple tree / As we go marching on." The Times reported that they tried to burn the effigy but, unable to light it, threw it in the Thames instead.
Women's suffrage meetings were invaded, although the students knew that not all suffragettes were anti-vivisectionists. A meeting organised by Millicent Fawcett on 5 December 1907 at the Paddington Baths Hall in Bayswater was left with chairs and tables smashed and one steward with a torn ear. Two fireworks were let off, and Fawcett's speech was drowned out by students singing "John Brown's Body", after which they marched down Queen's Road led by someone with bagpipes. The Daily Express reported the meeting as "Medical Students' Gallant Fight with Women".
10 December 1907
The rioting reached its height five days later, on Tuesday, 10 December, when 100 medical students tried to pull the memorial down. The previous protests had been spontaneous, but this one was organised to coincide with the annual Oxford–Cambridge rugby match at Queen's Club, West Kensington. The protesters hoped (in vain, as it turned out) that some of the thousands of Oxbridge students would swell their numbers. The intention was that, after toppling the statue and throwing it in the Thames, 2,000–3,000 students would meet at 11:30 pm in Trafalgar Square. Street vendors sold handkerchiefs stamped with the date of the protest and the words, "Brown Dog's inscription is a lie, and the statuette an insult to the London University."
In the afternoon, protesters headed for the statue, but were driven off by locals. The students proceeded down Battersea Park Road instead, intending to attack the Anti-Vivisection Hospital, but were again forced back. When one student fell from the top of a tram, the workers shouted that it was "the brown dog's revenge" and refused to take him to hospital. The British Medical Journal responded that, given that it was the Anti-Vivisection Hospital, the crowd's actions may have been "prompted by benevolence".
A second group of students headed for central London, waving effigies of the brown dog, joined by a police escort and, briefly, a busker with bagpipes. As the marchers reached Trafalgar Square, they were 400 strong, facing 200–300 police officers, 15 of them on horseback. The students gathered around Nelson's Column, where the ringleaders climbed onto its base to make speeches. While students fought with police on the ground, mounted police charged the crowd, scattering them into smaller groups and arresting the stragglers, including one undergraduate, Alexander Bowley, who was arrested for "barking like a dog". The fighting continued for hours before the police gained control. At Bow Street magistrate's court the next day, ten students were bound over to keep the peace; several were fined 40 shillings, or £3 if they had fought with police.
Strange relationships
Rioting broke out elsewhere over the following days and months, as medical and veterinary students united. Whenever Lizzy Lind af Hageby spoke, students would shout her down. When she arranged a meeting of the Ealing and Acton Anti-Vivisection Society at Acton Central Hall on 11 December 1906, over 100 students disrupted it, throwing chairs and stink bombs, particularly when she objected to a student blowing her a kiss. The Daily Chronicle reported: "The rest of Miss Lind-af-Hageby's indignation was lost in a beautiful 'eggy' atmosphere that was now rolling heavily across the hall. 'Change your socks!' shouted one of the students." Furniture was smashed and clothing torn.
For Susan McHugh of the University of New England, the political coalition of trade unionists, socialists, Marxists, liberals and suffragettes that rallied to the statue's defence reflected the brown dog's mongrel status. The riots saw them descend on Battersea to fight the medical students, even though, she writes, the suffragettes were not a group toward whom male workers felt any warmth. But the "Brown Terrier Dog Done to Death" by the male scientific establishment united them all.
Lizzy Lind af-Hageby and Charlotte Despard saw the affair as a battle between feminism and machismo. According to Coral Lansbury, the fight for women's suffrage became closely linked with the anti-vivisection movement, and the iconography of vivisection struck a chord with women. Three of the four vice-presidents of the National Anti-Vivisection Hospital were women. Lansbury argues that the Brown Dog affair became a matter of opposing symbols: the vivisected dog on the operating board blurred into images of suffragettes force-fed in Brixton Prison, or women strapped down for childbirth or forced to have their ovaries and uteruses removed as a cure for mania. The "vivisected animal stood for vivisected woman".
Both sides saw themselves as heirs to the future. Hilda Kean writes that the Swedish activists were young and female, anti-establishment and progressive, and viewed the scientists as remnants of a previous age. Their access to higher education had made the case possible, creating what feminist scholar Susan Hamilton called a "new form of witnessing". Against this, Lansbury writes, the students saw themselves and their teachers as the "New Priesthood" and the women and trade unionists as representatives of superstition and sentimentality.
"Exit the 'Brown Dog'"
Questions were asked in the House of Commons about the cost of policing the statue, which required six constables a day at a cost of £700 a year. In February 1908 Sir Philip Magnus, MP for the London University constituency, asked the Home Secretary, Herbert Gladstone, "whether his attention has been called to the special expense of police protection of a public monument at Battersea that bears a controversial inscription". Gladstone replied that six constables were needed daily to protect the statue, and that the overall cost of extra policing had been equivalent to employing 27 inspectors, 55 sergeants, and 1,083 constables for a day.
London's police commissioner wrote to Battersea Council to ask that they contribute to the cost. Councillor John Archer, later Mayor of Battersea and the first black mayor in London, told the Daily Mail that he was amazed by the request, considering Battersea was already paying £22,000 a year in police rates. The Canine Defence League wondered whether, if Battersea were to organise raids on laboratories, the laboratories would be asked to pay the policing costs themselves.
Other councillors suggested the statue be encased in a steel cage and surrounded by a barbed wire fence. Suggestions were made through the letters pages of the Times and elsewhere that it be moved, perhaps to the grounds of the Anti-Vivisection Hospital. The British Medical Journal wrote in March 1910:
May we suggest that the most appropriate resting place for the rejected work of art is the Home for Lost Dogs at Battersea, where it could be "done to death", as the inscription says, with a hammer in the presence of Miss Woodword, the Rev. Lionel S. Lewis, and other friends; if their feelings were too much for them, doubtless an anaesthetic could be administered.
Battersea Council grew tired of the controversy. A new Conservative council was elected in November 1909 amid talk of removing the statue. There were protests in support of it, and the 500-strong Brown Dog memorial defence committee was established. Twenty thousand people signed a petition, and 1,500 attended a rally in February 1910 addressed by Lind af Hageby, Charlotte Despard and Liberal MP George Greenwood. There were more demonstrations in central London and speeches in Hyde Park, with supporters wearing masks of dogs.
The protests were to no avail. The statue was quietly removed before dawn on 10 March 1910 by four council workmen, accompanied by 120 police officers. Nine days later, 3,000 anti-vivisectionists gathered in Trafalgar Square to demand its return, but it was clear by then that Battersea Council had turned its back on the affair. The statue was at first hidden in the borough surveyor's bicycle shed, according to a letter his daughter wrote in 1956 to the British Medical Journal, then reportedly destroyed by a council blacksmith, who melted it down. Anti-vivisectionists filed a High Court petition demanding its return, but the case was dismissed in January 1911.
New memorial
On 12 December 1985, over 75 years after the statue's removal, a new memorial to the brown dog was unveiled by actress Geraldine James in Battersea Park behind the Pump House. Created by sculptor Nicola Hicks, the new bronze dog is mounted on a rectangular plinth of Portland stone and based on Hicks's own terrier, Brock. Three of the four plaques affixed to the column of the current Brown Dog statue bear the original inscriptions.
The British Medical Journal (Clinical Research Edition) published an editorial in March 1986,
"A new antivivisectionist libellous statue at Battersea", criticising Battersea Council and the Greater London Council for allowing it.
Echoing the fate of the previous memorial, the new dog was moved into storage in 1992 by Battersea Park's owners, the Conservative Borough of Wandsworth, they said as part of a park renovation scheme. Anti-vivisectionists campaigned for its return, suspicious of the explanation. It was reinstated in the park's Woodland Walk in 1994, near the Old English Garden, a more secluded spot than before.
The new statue was criticised in 2003 by historian Hilda Kean. She saw the old Brown Dog as a radical statement, upright and defiant: "The dog has changed from a public image of defiance to a pet". For Kean, the new Brown Dog, located near the Old English Garden as "heritage", is too safe; unlike its controversial ancestor, she argues, it makes no one uncomfortable.
On 6 September 2021, the 115th anniversary of when the original statue was unveiled, a new campaign was launched by author Paula S. Owen to recast the original statue. Owen is author of Little Brown Dog, a novel that is based on the true story.
See also
Animal welfare in the United Kingdom
List of public art in Wandsworth
Cruel Treatment of Cattle Act 1822
Cruelty to Animals Act 1835
Cruelty to Animals Act 1849
Cruelty to Animals Act 1876
Wild Animals in Captivity Protection Act 1900
Protection of Animals Act 1911
Protection of Animals Act 1934
Abandonment of Animals Act 1960
Animals (Scientific Procedures) Act 1986
Animal Welfare Act 2006
Animal Health and Welfare (Scotland) Act 2006
RSPCA
List of individual dogs
Sources
Notes
References
Works cited
Books
Journal articles
Royal Commissions
Further reading
Bayliss, Leonard (Spring 1957). "The 'Brown Dog' Affair". Potential (UCL magazine). 11–22.
Coult, Tony (1988). "The Strange Affair of the Brown Dog" (radio play based on Peter Mason's The Brown Dog Affair).
Coleridge, Stephen (1916). Vivisection, a heartless science. London: John Lane.
Elston, Mary Ann (1987). "Women and Anti-vivisection in Victorian England, 1870–1900", in Nicolaas Rupke (ed.). Vivisection in Historical Perspective. London: Routledge.
Gålmark, Lisa (1996). Shambles of Science: Lizzy Lind af Hageby and Leisa Schartau, Anti-vivisektionister 1903–1913/14. Stockholm: Stockholm University.
Harte, Negley; North, John (1991). The World of UCL, 1828–1990. London: Routledge (image of the restaged experiment on the brown dog, 127).
Le Fanu, James (23 November 2003). "In Sickness and in Health: Vivisection's Undoing". The Daily Telegraph.
McIntosh, Anthony (1 April 2021). "The Great British Art Tour: The Little Dog that Caused Violent Riots". The Guardian.
Statue locations
Location of the new Brown Dog, Old English Garden, Battersea Park on Wikimapia ()
Location of the old Brown Dog (now empty), Latchmere Recreation Ground on Wikimapia ()
1900s in England
1903 in British law
1903 in case law
1903 in England
1903 in London
1907 in London
1907 riots
Animal cruelty incidents
Animal rights
Animals in politics
Animal testing in the United Kingdom
Animal welfare and rights in the United Kingdom
Anti-vivisection movement
Buildings and structures in Battersea
Dogs in the United Kingdom
Dog monuments
English defamation case law
History of animal testing
Individual dogs
Outdoor sculptures in London
Political controversies in the United Kingdom
Political history of England
Public art in London
20th-century riots in London
1903 animal deaths | Brown Dog affair | Chemistry | 7,750 |
31,457,489 | https://en.wikipedia.org/wiki/Villa%20Girasole | The Villa Girasole (il girasole meaning ‘the sunflower’ in Italian) is a house constructed in the 1930s in Marcellise, northern Italy, near Verona. The conception of architect Angelo Invernizzi, the Girasole rotates to follow the sun as it moves, just as a sunflower opens up and turns to follow the sun. This is how the unique house got its name.
Architect
Angelo Invernizzi, a wealthy Italian engineer of Genoa, Italy, dreamed of building a house that would “maximize the health properties of the sun by rotating to follow it”. He designed the house for himself with the help of Romolo Carapacchi, a mechanical engineer; Fausto Saccorotti, an interior decorator; and Ettore Fagiuoli, an architect. Invernizzi’s daughter, Lidia Invernizzi, described in the 17-minute film “Il girasole: una casa vicino a Verona” by Marcel Meili and Christoph Schaub, Invernizzi could have built the house himself, but he instead invited many people to participate in its creation: painters, sculptors, furniture makers, and more. “People who believed in a new era: nothing should be built as before.” Having a family connection to Marcellise, even though working and living in Genoa, he wanted to build the house there in its hilly splendor and with its memories of a simpler life.
History and construction
Invernizzi first began drawing designs for his rotating house in 1929, but construction started in 1931, only during summer months. Invernizzi and his team used the project as a means to experiment with new materials, like concrete and fibre cement. "In keeping with the project's experimental nature, a considerable amount of adaptation and refinement accompanied construction". They ended up using aluminium sheeting to replace the concrete on the outside walls because the concrete had left cracks. At first, Invernizzi only expected the house to make a 180 degree turn, but eventually after he saw it make the 180 degree turn, he "decided to make the complete turn" of 360 degrees. The project was complete in 1935, after four years.
Interior/Exterior
The Girasole has two storeys and is shaped like the letter "L". It sits on an over 44 metre circular base, with a 42 metre tall tower at the centre. This is where the house rotates from, using motors. The "L" rotates "over three circular tracks where 15 trolleys can slide the 5,000 cubic metres building at a speed of 4 mm per second and it takes 9 hours and 20 minutes to rotate fully". There is a manual control panel located in the moving part of the house that is used to control its rotation. The first floor of the moving part is known as the "day zone", and includes the dining room, the music room, Mr. and Mrs. Invernizzi’s studies, with the kitchen, pantry, and toilet located right near the central tower. An assortment of bedrooms and bathrooms are found on the second floor. Villa Girasole’s interior design is such that one experiences a number of different progressions of light throughout the day: "Though the views from either wing differ at any given moment, they share a general orientation to the sun, reducing the chance for conflict over which direction the house should point. All rooms could share an equal amount of daylight or shade".
Machinery
Villa Girasole runs on two diesel fuel motors which move the house over circular tracks and allow trolleys to slide the house along. It has been suggested that because the front of the house faces the sun all day, installing solar panels on the roof would be beneficial: gaining and storing energy for those times when the sun is not out.
References
External links
(with images)
Villa Girasole on Architectuul
Girasole
Solar design
Houses completed in 1930 | Villa Girasole | Engineering | 808 |
11,347,599 | https://en.wikipedia.org/wiki/Diaporthe%20arctii | Diaporthe arctii is a fungal plant pathogen.
Subspecies
Diaporthe arctii var. achilleae
References
Fungal plant pathogens and diseases
arctii
Fungi described in 1833
Fungus species | Diaporthe arctii | Biology | 43 |
31,629,968 | https://en.wikipedia.org/wiki/The%20Model%20home%202020%20project | The model home 2020 project is a vision for climate neutral buildings with a high degree of liveability. The project was started in 2009 and involves the construction of six houses in five countries across Europe.
Each building in the project is designed to reflect and respond to the different climatic, cultural and architectural conditions of the countries in which they are built. After completion the houses are open to the public during a test period of 6–12 months after which they are sold. Each house is monitored during the test period to learn how the experiments turn out in real-life conditions.
The learnings will be shared openly with other projects, industry experts and contractors to create synergy effects in the building industry's effort to come up with solutions for sustainable buildings.
The houses in Denmark were built in 2009, those in Germany and Austria were built in 2010 and those in the UK and France are scheduled for completion in 2011.
Background
The Active House Alliance has developed a set of principles for "active house" construction, which focuses on achieving a balance between energy, indoor climate and the environment. The model home 2020 project is in full accordance with the active house principles.
The project is backed by the VELUX Group in cooperation with multiple local and regional governments, suppliers, architects, engineers and researchers. The model home 2020 project tests how the active house principles perform under real-life conditions. The knowledge derived from the projects will be documented and used to take an active part in developing sustainable buildings.
The projects
Experiment # 1 Home for Life in Denmark built in 2009. Home for Life is a visionary proposal for the family home of the future. The building is the result of an interdisciplinary project to incorporate the issues of energy consumption, comfort and visual appeal into a holistic entity, with these parameters being mutually complementary and maximising quality of life in the home and the world around it.
Experiment # 2 Green Lighthouse in Denmark built in 2009. Green Lighthouse is Denmark's first public carbon-neutral building. It was developed in a strategic partnership between the University of Copenhagen, the VELUX Group, VELFAC, the Danish University and Property Agency and the Municipality of Copenhagen. The underlying vision of the project is to erect a beacon showing the way towards climate-neutral buildings of the future that provide the best indoor climate with masses of daylight and fresh air to the benefit of the residents' health and comfort.
Experiment # 3 Sunlighthouse in Austria built in 2010. Sunlighthouse will be Austria's first carbon-neutral, single-family home. The vision is to build a house with exciting and appealing architecture focusing on the sloping roof. The house must be generally affordable and therefore meet certain specifications of dimensions, material and appearance. Sunlighthouse provides an exceptionally high proportion of daylight and will achieve a positive energy balance by reducing its overall energy consumption and by using renewable energy.
Experiment # 4 LichtAktiv Haus in Germany built in 2010. LichtAktiv Haus is the first -neutral modernisation of a so-called Siedlerhaus, a semi-detached house from the 1950s located in the Wilhelmsburg district of Hamburg The innovative modernisation strategy combines maximum liveability with optimum energy efficiency. The once tight and closed structure of the building has been transformed into spacious rooms with high levels of daylight, providing occupants with the best living comfort. Natural ventilation ensures a healthy indoor climate. The goal now is self-sufficiency in energy.
Experiment # 5 CarbonLight Homes in UK opened during 2011. CarbonLight homes are the first new home in the UK designed and built to the new UK Government definition of zero carbon. They are designed to be real homes for real people with construction techniques suitable for use by mass house builders. CarbonLight Homes use nature in an intelligent way to maximise daylight and encourage a sustainable lifestyle. The design is open plan and incorporates high levels of daylight and natural ventilation intended to minimise energy consumption among residents and generate a sense of community. The homes show that common-sense design can be used to create inspirational sustainable houses that can be easily replicated by UK house builders.
Experiment # 6 Maison Air et Lumière in France opened during 2011. Maison Air et Lumière is a new generation of active homes that puts the quality of life of its inhabitants at the centre of its environmental approach. The unique features of the house lie in intelligent use of the sloping roof to combine well-being and energy efficiency. The architectural concept is based on different roof pitches that increase its ability to capture sunlight, making it an energy-positive home.
The challenges
The European Union (EU) has adopted a comprehensive package for European energy policy up to 2020. It entails EU member states reducing their total energy consumption and CO2 emissions by 20 percent. Moreover, all EU member states must show that 20 percent of their total energy consumption comes from renewable energy sources. According to EU statistics:
People in the EU spend 90 percent of the time indoors.
Buildings consume more than 40 percent of the EU's total energy consumption.
Up to 30 percent of the buildings within the EU do not provide a healthy indoor climate.
References
External links
Ecobuild blog
European Commission - Energy 2020
Model home 2020 website
Story from UK about model home 2020
Film about Green Lighthouse
Learnings from the Model Home 2020 project
Sustainable architecture | The Model home 2020 project | Engineering,Environmental_science | 1,062 |
648,787 | https://en.wikipedia.org/wiki/Aryl%20halide | In organic chemistry, an aryl halide (also known as haloarene) is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. Haloarenes are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications.
Classification according to halide
Aryl fluorides
Aryl fluorides are used as synthetic intermediates, e.g. for the preparation of pharmaceuticals, pesticides, and liquid crystals. The conversion of diazonium salts is a well established route to aryl fluorides. Thus, anilines are precursors to aryl fluorides. In the classic Schiemann reaction, tetrafluoroborate is the fluoride donor:
In some cases, the fluoride salt is used:
Many commercial aryl fluorides are produced from aryl chlorides by the Halex process. The method is often used for aryl chlorides also bearing electron-withdrawing groups. Illustrative is the synthesis of 2-fluoronitrobenzene from 2-nitrochlorobenzene:
Aryl chlorides
Aryl chlorides are the aryl halides produced on the largest scale commercially: 150,000 tons/y in the US alone (1994). Production levels are decreasing owing to environmental concerns. Chlorobenzenes are used mainly as solvents.
Friedel-Crafts halogenation or "direct chlorination" is the main synthesis route. Lewis acids, e.g. iron(III) chloride, catalyze the reactions. The most abundantly produced aryl halide, chlorobenzene, is produced by this route:
Monochlorination of benzene is accompanied by formation of the dichlorobenzene derivatives. Arenes with electron donating groups react with halogens even in the absence of Lewis acids. For example, phenols and anilines react quickly with chlorine and bromine water to give multihalogenated products. Many detailed laboratory procedures are available. For alkylbenzene derivatives, e.g. toluene, the alkyl positions tend to be halogenated by free radical conditions, whereas ring halogenation is favored in the presence of Lewis acids. The decolouration of bromine water by electron-rich arenes is used in the bromine test.
The oxychlorination of benzene has been well investigated, motivated by the avoidance of HCl as a coproduct in the direct halogenation:
This technology is not widely used however.
The Gatterman reaction can also be used to convert diazonium salts to chlorobenzenes using copper-based reagents. Owing to high cost of diazonium salts, this method is reserved for specialty chlorides.
Aryl bromides
The main aryl bromides produced commercially are tetrabromophthalic anhydride, decabromodiphenyl ether, and tetrabromobisphenol-A. These materials are used as flame retardants. They are produced by direct bromination of phenols and aryl ethers. Phthalic anhydride is poorly reactive toward bromine, necessitating the use of acidic media.
The Gatterman reaction can also be used to convert diazonium salts to bromobenzenes using using copper-based reagents. Owing to high cost of diazonium salts, this method is reserved for specialty bromides.
Aryl iodides
Synthetic aryl iodides are used as X-ray contrast agents, but otherwise these compounds are not produced on a large scale. Aryl iodides are "easy" substrates for many reactions such as cross-coupling reactions and conversion to Grignard reagents, but they are much more expensive than the lighter, less reactive aryl chlorides and bromides.
Aryl iodides can be prepared by treating diazonium salts with iodide salts. Electron-rich arenes such as anilines and dimethoxy derivatives react directly with iodine.
Aryl lithium and aryl Grignard reagents react with iodine to give the aryl halide:
This method is applicable to the preparation of all aryl halides. One limitation is that most, but not all, aryl lithium and Grignard reagents are produced from aryl halides.
Classification according to aryl group
Halobenzenes and halobenzene derivatives
Although the term aryl halide includes halogenated derivatives of any aromatic compound, it commonly refers to halobenzenes, which are specifically halogenated derivatives of benzene. Groups of halobenzenes include fluorobenzenes, chlorobenzenes, bromobenzenes, and iodobenzenes, as well as mixed halobenzenes containing at least two different types of halogens bonded to the same benzene ring. There are also many halobenzene derivatives.
Halopyridines
Halopyridines are based on the aromatic compound pyridine. This includes chloropyridines and bromopyridines. Chloropyridines are important intermediates to pharmaceuticals and agrochemicals.
Halogenated naphthalenes
Halogenated naphthalenes are based on naphthalene. Polychlorinated naphthalenes were used extensively from the 1930s to 1950s in cable and capacitor production, due to their insulating, hydrophobic, and flame retardant properties, but they have since been phased out for this use due to toxicity, environmental persistence, and introduction of new materials.
Aryl halides in nature
The thyroid hormones triiodothyronine (T3) and thyroxine (T4) are aryl iodides. A tetraiodide, T4 is biosynthesised by electrophilic iodination of tyrosine derivative. Synthetic T4 is one of the most heavily prescribed medicines in the U.S.
Many chlorinated and brominated aromatic compounds are produced by marine organisms. The chloride and bromide in ocean waters are the source of the halogens. Various peroxidase enzymes (e.g., bromoperoxidase) catalyze the reactions. Numerous are derivatives of electron-rich rings found in tyrosine, tryptophan, and various pyrroles. Some of these natural aryl halides exhibit useful medicinal properties.
Structural trends
The C-X distances for aryl halides follow the expected trend. These distances for fluorobenzene, chlorobenzene, bromobenzene, and methyl 4-iodobenzoate are 135.6(4), 173.90(23), 189.8(1), and 209.9 pm, respectively.
Reactions
Substitution
Unlike typical alkyl halides, aryl halides typically do not participate in conventional substitution reactions. Aryl halides with electron-withdrawing groups in the ortho and para positions, can undergo SNAr reactions. For example, 2,4-dinitrochlorobenzene reacts in basic solution to give a phenol.
Unlike in most other substitution reactions, fluoride is the best leaving group, and iodide the worst. A 2018 paper indicates that this situation may actually be rather common, occurring in systems that were previously assumed to proceed via SNAr mechanisms.
Benzyne
Aryl halides often react via the intermediacy of benzynes. Chlorobenzene and sodium amide react in liquid ammonia to give aniline by this pathway.
Organometallic reagent formation
Aryl halides react with metals, generally lithium or magnesium, to give organometallic derivatives that function as sources of aryl anions. By the metal-halogen exchange reaction, aryl halides are converted to aryl lithium compounds. Illustrative is the preparation of phenyllithium from bromobenzene using n-butyllithium (n-BuLi):
C6H5Br + BuLi → C6H5Li + BuBr
Direct formation of Grignard reagents, by adding the magnesium to the aryl halide in an ethereal solution, works well if the aromatic ring is not significantly deactivated by electron-withdrawing groups.
Other reactions
The halides can be displaced by strong nucleophiles via reactions involving radical anions. Alternatively aryl halides, especially the bromides and iodides, undergo oxidative addition, and thus are subject to Buchwald–Hartwig amination-type reactions.
Chlorobenzene was once the precursor to phenol, which is now made by oxidation of cumene. At high temperatures, aryl groups react with ammonia to give anilines.
Biodegradation
Rhodococcus phenolicus is a bacterium that degrades dichlorobenzene as sole carbon sources.
Applications
The aryl halides produced on the largest scale are chlorobenzene and the isomers of dichlorobenzene. One major but discontinued application was the use of chlorobenzene as a solvent for dispersing the herbicide Lasso. Overall, production of aryl chlorides (also naphthyl derivatives) has been declining since the 1980s, in part due to environmental concerns. Triphenylphosphine is produced from chlorobenzene:
3 C6H5Cl + PCl3 + 6 Na → P(C6H5)3 + 6 NaCl
Aryl bromides are widely used as fire-retardants. The most prominent member is tetrabromobisphenol-A, which is prepared by direct bromination of the diphenol.
References
Aromatic compounds
Organohalides | Aryl halide | Chemistry | 2,091 |
5,580,714 | https://en.wikipedia.org/wiki/Proliferating%20cell%20nuclear%20antigen | Proliferating cell nuclear antigen (PCNA) is a DNA clamp that acts as a processivity factor for DNA polymerase δ in eukaryotic cells and is essential for replication. PCNA is a homotrimer and achieves its processivity by encircling the DNA, where it acts as a scaffold to recruit proteins involved in DNA replication, DNA repair, chromatin remodeling and epigenetics.
Many proteins interact with PCNA via the two known PCNA-interacting motifs PCNA-interacting peptide (PIP) box and AlkB homologue 2 PCNA interacting motif (APIM). Proteins binding to PCNA via the PIP-box are mainly involved in DNA replication whereas proteins binding to PCNA via APIM are mainly important in the context of genotoxic stress.
Function
The protein encoded by this gene is found in the nucleus and is a cofactor of DNA polymerase delta. The encoded protein acts as a homotrimer and helps increase the processivity of leading strand synthesis during DNA replication. In response to DNA damage, this protein is ubiquitinated and is involved in the RAD6-dependent DNA repair pathway. Two transcript variants encoding the same protein have been found for this gene. Pseudogenes of this gene have been described on chromosome 4 and on the X chromosome.
PCNA is also found in archaea, as a processivity factor of polD, the single multi-functional DNA polymerase in this domain of life.
Expression in the nucleus during DNA synthesis
PCNA was originally identified as an antigen that is expressed in the nuclei of cells during the DNA synthesis phase of the cell cycle. Part of the protein was sequenced and that sequence was used to allow isolation of a cDNA clone. PCNA helps hold DNA polymerase delta (Pol δ) to DNA. PCNA is clamped to DNA through the action of replication factor C (RFC), which is a heteropentameric member of the AAA+ class of ATPases. Expression of PCNA is under the control of E2F transcription factor-containing complexes.
Role in DNA repair
Since DNA polymerase epsilon is involved in resynthesis of excised damaged DNA strands during DNA repair, PCNA is important for both DNA synthesis and DNA repair.
PCNA is also involved in the DNA damage tolerance pathway known as post-replication repair (PRR). In PRR, there are two sub-pathways:
(1) a translesion synthesis pathway, which is carried out by specialised DNA polymerases that are able to incorporate damaged DNA bases into their active sites (unlike the normal replicative polymerase, which stall), and hence bypass the damage, and
(2) a proposed "template switch" pathway that is thought to involve damage bypass by recruitment of the homologous recombination machinery.
PCNA is pivotal to the activation of these pathways and the choice as to which pathway is utilised by the cell. PCNA becomes post-translationally modified by ubiquitin. Mono-ubiquitin of lysine number 164 on PCNA activates the translesion synthesis pathway. Extension of this mono-ubiquitin by a non-canonical lysine-63-linked poly-ubiquitin chain on PCNA is thought to activate the template switch pathway. Furthermore, sumoylation (by small ubiquitin-like modifier, SUMO) of PCNA lysine-164 (and to a lesser extent, lysine-127) inhibits the template switch pathway. This antagonistic effect occurs because sumoylated PCNA recruits a DNA helicase called Srs2, which has a role in disrupting Rad51 nucleoprotein filaments fundamental for initiation of homologous recombination.
PCNA-binding proteins
PCNA interacts with many proteins.
Apoptotic factors
ATPases
Base excision repair enzymes
Cell-cycle regulators
Chromatin remodeling factor
Clamp loader
Cohesin
DNA ligase
DNA methyltransferase
DNA polymerases
E2 SUMO-conjugating enzyme
E3 ubiquitin ligases
Flap endonuclease
Helicases
Histone acetyltransferase
Histone chaperone
Histone deacetylase
Mismatch repair enzymes
Licensing factor
NKp44 receptor
Nucleotide excision repair enzyme
Poly ADP ribose polymerase
Procaspases
Protein kinases
TCP protein domain
Topoisomerase
Interactions
PCNA has been shown to interact with:
Annexin A2
CAF-1
CDC25C
CHTF18
Cyclin D1
Cyclin O
Cyclin-dependent kinase 4
Cyclin-dependent kinase inhibitor 1C
DNMT1
EP300
Establishment of Sister Chromatid Cohesion 2
Flap structure-specific endonuclease 1
GADD45A
GADD45G
HDAC1
HUS1
ING1
KCTD13
KIAA0101
Ku70
Ku80
MCL1
MSH3
MSH6
MUTYH
P21
POLD2
POLD3
POLDIP2
POLH
POLL
RFC1
RFC2
RFC3
RFC4
RFC5
Ubiquitin C
Werner syndrome ATP-dependent helicase
XRCC1
Y box binding protein 1
Proteins interacting with PCNA via APIM include human AlkB homologue 2, TFIIS-L, TFII-I, Rad51B, XPA, ZRANB3, and FBH1.
Uses
Antibodies against proliferating cell nuclear antigen (PCNA) or monoclonal antibody termed Ki-67 can be used for grading of different neoplasms, e.g. astrocytoma. They can be of diagnostic and prognostic value. Imaging of the nuclear distribution of PCNA (via antibody labeling) can be used to distinguish between early, mid and late S phase of the cell cycle. However, an important limitation of antibodies is that cells need to be fixed leading to potential artifacts.
On the other hand, the study of the dynamics of replication and repair in living cells can be done by introducing translational fusions of PCNA. To eliminate the need for transfection and bypass the problem of difficult to transfect and/or short lived cells, cell permeable replication and/or repair markers can be used. These peptides offer the distinct advantage that they can be used in situ in living tissue and even distinguish cells undergoing replication from cells undergoing repair.
caPCNA, a post-translationally modified isoform of PCNA common in cancer cells, is a potential therapeutic target in cancer therapy. In 2023 City of Hope National Medical Center published preclinical research on a targeted chemotherapy using AOH1996 that appears to suppress tumor growth without causing discernable side effects.
See also
Ki-67 – cellular marker for proliferation
Transcription
References
Further reading
External links
ANA: Cell cycle related (Mitotic): PCNA type 1 and type 2 Antibody Patterns—Antibody Patterns.com
Cell cycle regulators
DNA replication
DNA repair
Proteins | Proliferating cell nuclear antigen | Chemistry,Biology | 1,455 |
8,635,906 | https://en.wikipedia.org/wiki/Brown%20truss | A Brown truss is a type of bridge truss, used in covered bridges. It is noted for its economical use of materials and is named after the inventor, Josiah Brown Jr., of Buffalo, New York, who patented it July 7, 1857, as US patent 17,722.
Description
The Brown truss is a box truss that is a through truss (as contrasted with a deck truss) and consists of diagonal cross compression members connected to horizontal top and bottom stringers. There may be vertical or almost vertical tension members (the diagram shows these members, while the patent application diagram does not) but there are no vertical members in compression. In practice, when used in a covered bridge, the most common application, the truss is protected with outside sheathing.
The floor and roof are also trusses, but are horizontal and serve to give the truss rigidity. The bottoms of the diagonals tend to protrude below the sheathing. The Brown truss is noted for economy of materials as it can be built with very little metal.
Patent
Brown's patent claims did not actually address the economy afforded by lack of vertical members ("braces"). Instead he focused on the improved strength over previous trusses that had members ("braces" in his terminology) come to the horizontal chord near to each other but not exactly together (at "gains" in his terminology), by having several members come together in the same place. From the patent text:
I do not claim broadly furnishing the main or counter braces with gains and passing them between the timbers of the chords;
What I do claim as my invention, and desire to secure by letters Patent, is— Providing each of the main and counter braces with two gains at top and bottom, and each of the timbers of the chord with a gain at the point where the braces are applied corresponding with the gains in the braces, and the braces thus formed up between the timber, with the gains of the braces in such relation to the gains of the timbers that when the timbers of the chords are brought together they are combined and become, as it were, only one piece, no part of which can be operated upon or affected independently of the other by the downward and upward thrusts common to truss bridges, even if the bolt which passes laterally through and intersects each set of braces and the timbers of the chord were removed.
History
The Brown truss enjoyed a brief period of favor in the 1860s, and is known to have been used in four covered bridges in Michigan, the Ada Covered Bridge, the Fallasburg Bridge, Whites Bridge and one other. The design did not appear to gain wide acceptance as modern bridges tend to be Howe, Pratt, bowstring or Warren trusses.
See also
Truss bridge for bridges employing various truss types
References
Truss bridges by type
American inventions
Trusses | Brown truss | Technology | 579 |
21,053,458 | https://en.wikipedia.org/wiki/Cholera%20vaccine | A cholera vaccine is a vaccine that is effective at reducing the risk of contracting cholera. The recommended cholera vaccines are administered orally to elicit local immune responses in the gut where the intestinal cells produce antibodies against the cholera microbe. This immune response was poorly achieved with the injectable vaccines that were used until the 1970s. The first effective oral cholera vaccine was Dukoral, developed in Sweden in the 1980s. For the first six months after vaccination it provides about 85% protection, which decreases to approximately 60% during the first two years. When enough of the population is immunized, it may protect those who have not been immunized thereby increasing the total protective impact to more than 90 % (known as herd immunity).
The World Health Organization (WHO) recommends the use of three oral cholera vaccines – Dukoral, Shanchol, and Euvichol-Plus – in combination with other measures among those at high risk for cholera. Two vaccine doses with a 1–6 week interval are typically recommended. The duration of protection is at least two years in adults and six months in children aged 1–5 years. A live, attenuated single-dose oral vaccine is available for those traveling to an area where cholera is common but is not WHO approved for public health use.
The available types of oral cholera vaccine are generally considered safe for the majority of the population. These vaccines were shown to be safe in pregnancy and in those with poor immune function. The main side effects that could be experienced include mild abdominal pain or diarrhea.
The first cholera vaccines were developed in the late 19th century. They were the first widely used vaccines that were made in a laboratory but were largely abandoned in the 1970s due to their then-documented reactogenicity and poor efficacy.
Oral cholera vaccines were first introduced in the 1990s. It is on the World Health Organization's List of Essential Medicines.
These vaccines are licensed for use in more than 60 countries. In countries where the disease is common, the vaccine appears to be cost-effective.
Medical use
In the late 20th century, oral cholera vaccines started to be used on a massive scale, with millions of vaccinations taking place, as a tool to control cholera outbreaks in addition to the traditional interventions of improving safe water supplies, sanitation, handwashing, and other means of improving hygiene. The Dukoral vaccine, which combines formalin- and heat-killed whole cells of Vibrio cholerae O1 and a recombinant cholera toxin B subunit, was licensed in 1991 and has been used widely, mainly for travellers. The Shanchol bivalent vaccine, which combines the O1 and O139 serogroups, was originally developed in Vietnam under the name mORCVAX in 1997 and given in 20 million doses in Vietnam's public health programme during the following decade through targeted mass vaccination of school-aged children in cholera endemic regions.
The World Health Organization (WHO) recommends both preventive and reactive use of the vaccine, making the following key statements:
The observed vaccine-specific protection with two doses of the oral vaccine was 58–76%. Herd immunity can multiply the effectiveness of vaccination. Dukoral has been licensed for children two years of age and older, Shanchol and Euvichol-Plus for children one year of age and older. The administration of the vaccine to adults confers additional indirect protection (herd immunity) also to children.
, the WHO established a revolving stockpile, initially of only 2 million oral cholera vaccine doses. With donations from mainly the GAVI Alliance the stockpile has progressively expanded to now more than 40 million doses per year. It consists mainly of the Euvichol-Plus oral cholera vaccine being produced in South Korea. In total more than 150 million doses from the stockpile have been given in mass campaigns against both epidemic and endemic cholera in more than 25 cholera-affected countries. A set goal of WHO's Global Task Force for Cholera Control (GTFCC) is, by using oral cholera vaccine and other available tools, by 2030 to have reduced cholera deaths by more than 90% and stopped transmission globally.
Oral
The oral vaccines are generally of two forms: inactivated and attenuated.
The first developed effective oral cholera vaccine, Dukoral, is a monovalent inactivated vaccine containing killed whole cells of V. cholerae O1 plus additional recombinant cholera toxin B subunit. Bacterial strains of both Inaba and Ogawa serotypes and of El Tor and Classical biotypes are included in the vaccine. Dukoral is taken orally with bicarbonate buffer, which protects the antigens from gastric acid. The vaccine acts by inducing antibodies against both the bacterial components and CTB. The antibacterial intestinal antibodies prevent the bacteria from attaching to the intestinal wall, thereby impeding colonisation of V. cholerae O1. The anti-toxin intestinal antibodies prevent the cholera toxin from binding to the intestinal mucosal surface, thereby preventing the toxin-mediated diarrhoeal symptoms.
The two later inactivated oral cholera vaccines recommended by WHO, Shanchol, and Euvichol-Plus, have an identical composition, containing killed whole cells of V. cholerae O1 (the same components as in Dukoral) plus formalin-killed V. cholerae O139 bacteria.
A live, attenuated oral vaccine (CVD 103-HgR or Vaxchora), derived from a serogroup O1 classical Inaba strain, was approved for use in travellers by the US FDA in 2016.
In 2024, the Euvichol-S vaccine, an optimized version of Euvichol-Plus, received WHO prequalification. This streamlined formulation is designed to maintain effectiveness while reducing production costs, significantly boosting the global oral cholera vaccine supply to 50 million doses, up from 38 million. This increase addresses the growing demand amid rising cholera outbreaks since 2021.
Injectable
Although rarely in use, the injected cholera vaccines can be effective for people living where cholera is common. While being ineffective in young children, in such areas they can offer some degree of protection in adults and older children for up to six months.
Side effects
Both the inactivated and attenuated oral vaccines available are generally safe. Some of the common side effects include mild abdominal pain or diarrhea. They are safe in pregnancy and in those with poor immune function.
History of development
The first cholera vaccines were developed in the late 19th century. There were several pioneers in the development of the vaccine:
The first known attempt at a cholera vaccine was made by Louis Pasteur and it was aimed at preventing cholera in chickens. This was the first widely used vaccine that was made in a laboratory. Later use showed this early cholera vaccine to be ineffective.
In 1884, Spanish physician Jaume Ferran i Clua developed a live vaccine he had isolated from cholera patients in Marseilles, and used it on over 30,000 individuals in Valencia during that year's epidemic. However, his vaccine and inoculation was rather controversial and was rejected by his peers and several investigation commissions, but it ended up demonstrating its effectiveness and being recognized for it.
In 1892, Waldemar Haffkine developed an effective vaccine with less severe side effects, later testing it on more than 40,000 people in the Calcutta area from 1893 to 1896. His vaccine was accepted by the medical community, and is credited as the first effective human cholera vaccine.
Finally, in 1896, Wilhelm Kolle introduced a heat-killed vaccine that was significantly easier to prepare than Haffkine's, using it on a large scale in Japan in 1902.
Oral cholera vaccines were first introduced in the 1990s.
Society and culture
Legal status
In 2016, the US Food and Drug Administration (FDA) approved Vaxchora, a single-dose oral vaccine to prevent cholera for travelers. , Vaxchora is the only FDA-approved vaccine for the prevention of cholera.
Economics
The cost to immunize against cholera is between and $4.00 per vaccination.
The Vaxchora vaccine can cost more than $250.
References
Further reading
External links
Inactivated vaccines
Vaccines
World Health Organization essential medicines (vaccines)
Wikipedia medicine articles ready to translate | Cholera vaccine | Biology | 1,688 |
41,681,290 | https://en.wikipedia.org/wiki/Datafly%20algorithm | Datafly algorithm is an algorithm for providing anonymity in medical data. The algorithm was developed by Latanya Arvette Sweeney in 1997−98. Anonymization is achieved by automatically generalizing, substituting, inserting, and removing information as appropriate without losing many of the details found within the data. The method can be used on-the-fly in role-based security within an institution, and in batch mode for exporting data from an institution.
Organizations release and receive medical data with all explicit identifiers—such as name—removed, in the erroneous belief that patient confidentiality is maintained because the resulting data look anonymous. However the remaining data can be used to re-identify individuals by linking or matching the data to other databases or by looking at unique characteristics found in the fields and records of the database itself.
The Datafly algorithm has been criticized for trying to achieve anonymization by overgeneralization. The algorithm selects the attribute with the greatest number of distinct values as the one to generalize first.
Core algorithm
An outline of the Datafly algorithm is presented below.
Input:
Private Table PT; quasi-identifier QI = ( A1, ..., An ), k-anonymity constraint k; domain generalization hierarchies DGHAi, where i = 1,...,n with accompanying functions fAi, and loss, which is a limit on the percentage of tuples that can be suppressed. PT[id] is the set
of unique identifiers or keys for each tuple.
Output:
MGT a generalization of PT[QI] that enforces k-anonymity
Assumes: | PT | ≤ k, and loss * | PT | = k
algorithm Datafly:
// Construct a frequency list containing unique sequences of values across the quasi-identifier in PT,
// along with the number of occurrences of each sequence.
1. let freq be an expandable and collapsible vector with no elements initially. Each element is of the form ( QI, frequency, SID ), where SID = { idi : ∃ t[id] ∈ [id] ⇒ t[id] = idi }; and, frequency = |SID|. Therefore, freq is also accessible as a table over (QI, frequency, SID).
2. let pos 0, total 0
3. while total ≠ |PT| do
3.1 freq[pos] ( t[QI], occurs, SID ) where t[QI] ∈ [QI], ( t[ QI ],__, ___ ) freq; occurs = |PT| - |PT[QI] – {t[QI]}|; and, SID = { idi : ∃ t[id] PT[id] ⇒ t[id] = idi }
3.2 pos pos + 1, total total + occurs
// Make a solution by generalizing the attribute with the most number of distinct values
// and suppressing no more than the allowed number of tuples.
4. let belowk 0
5. for pos 1 to |freq| do
5.1 ( __, count ) freq[pos]
5.2 if count < k then do
5.2.1 belowk belowk + count
6. if belowk > k then do: // Note. loss * |PT| = k.
6.1 freq generalize(freq)
6.2 go to step 4
7. else do
// assert: the number of tuples to suppress in freq is ≤ loss * |PT|
7.1 freq suppress(freq, belowk )
7.2 MGT reconstruct(freq)
8. return MGT.
References
External links
Details of the Datafly algorithm
Privacy
Anonymity
Medical records
Data protection
Datasets
Obfuscation
Articles with example pseudocode | Datafly algorithm | Technology | 827 |
4,389,255 | https://en.wikipedia.org/wiki/Dragon%27s%20Egg | Dragon's Egg is a 1980 hard science fiction novel by American writer Robert L. Forward. In the story, Dragon's Egg is a neutron star with a surface gravity 67 billion times that of Earth, and inhabited by cheela, intelligent creatures the size of sesame seeds who evolve, live, and think a million times faster than humans. Most of the novel, from May to June 2050, chronicles the cheela civilization beginning with its discovery of agriculture to advanced technology and its first face-to-face contact with humans, who are observing the hyper-rapid evolution of the cheela civilization from orbit around Dragon's Egg.
As is typical of the genre, Dragon's Egg attempts to communicate unfamiliar ideas and imaginative scenes while giving adequate attention to the known scientific principles involved.
Plot summary
The neutron star
Half a million years ago and 50 light-years from Earth, a star in the constellation Draco turns supernova, and the star's remnant becomes a neutron star. The radiation from the explosion causes mutations in many Earth organisms, including a group of hominina that become the ancestors of Homo sapiens. The star's short-lived plasma jets are lop-sided because of anomalies in its magnetic field, and set it on a course passing within 250 astronomical units of the Sun. In 2020 AD, human astronomers detect the neutron star, call it "Dragon's Egg", and in 2050 they send an expedition to explore it.
The star contains about half of a solar mass of matter, compressed into a diameter of about , making its surface gravity 67 billion times that of Earth. Its outer crust, compressed to about 7,000 kg per cubic centimeter, is mainly iron nuclei with a high concentration of neutrons, overlaid with about of white dwarf star material. The atmosphere, mostly iron vapor, is about thick. The star shrinks slightly as it cools, causes the crust to crack and produce mountains high. Large volcanoes, formed by liquid material oozing from deep cracks, can be many centimeters high and hundred meters in diameter, and will eventually collapse, causing starquakes.
Around 3000 BC Dragon's Egg cools enough to allow a stable equivalent of "chemistry", in which "compounds" are constructed of nuclei bound by the strong force, rather than of Earth's atoms bound by the electromagnetic force. As the star's chemical processes are about one million times faster than Earth's, self-replicating "molecules" appear shortly and life begins on the star. As the star continues to cool, more complex life evolves, until plant-like organisms appear around 1000 BC. One lineage of these later became the first "animals", the earliest of these stealing seedpods from sessile organisms and some later lineages becoming predators.
The adults of the star's most intelligent species, called cheela (no flexion for gender or number), have about the same mass as an adult human. However, the extreme gravity of Dragon's Egg compresses the cheela to the volume of a sesame seed, but with a flattened shape about high and about in diameter. Their eyes are wide. Such minute eyes can see clearly only in ultraviolet and, in good light, the longest wavelengths of the X-ray band.
Growth of civilization
In 2032, a cheela develops the race's first weapon and tactics while overcoming a dangerous predator. In November 2049 a human expedition to Dragon's Egg starts building orbital facilities. The rest of the story, including almost the whole history of cheela civilization, spans from 22 May 2050 to 21 June 2050. By humans' standards, a "day" on Dragon's Egg is about 0.2 seconds, and a typical cheela's lifetime is about 40 minutes.
One clan organizes the first cheela agriculture, which brings predictable food supply but provokes grumbling about the repetitive work. Shortly after, a volcano emerges in the area, and the clan invents the first sledge to carry food from more distant sources. However, within a few generations the volcano pollutes the soil. One clan leads its population on a long, arduous journey to new territory that is fertile and uninhabited. Although one genius invents mathematics to calculate and measure the band's food supply, the situation is desperate and the clan's survival depends on the self-sacrifice of the oldest members.
Over the course of generations, the cheela come to worship the humans' spacecraft as a god, and their records of its satellites' movements cause them to develop writing. Several generations later, the cheela build an arena to accommodate thousands of worshippers. The humans notice this novel and very regular feature, conclude that intelligent beings inhabit the star, and use a laser to send simple messages. Cheela astronomers gradually realize that these are diagrams of the spaceships, its satellites and its crew – impossibly spindly creatures, who communicate with frustrating slowness, and are apparently almost 10% as long as the cheela's great arena. A cheela engineer proposes to send messages to the humans. As her attempts to transmit from the civilization's territory are ineffective, she travels to a mountain range to transmit directly under the spacecraft – conquering the fear of heights that is instinctive for flattened creatures living in 67 billion g. The humans recognize her message and realize that the cheela live a million times faster than humans.
Since real-time conversations are impossible, the humans send sections of the expedition's library. After reading an astronomy article, a cheela realizes that the supernova half a million human years ago created both their races. Many cheela generations later, but only a few hours for humans, cheelas develop gravity manipulation. A few generations later, a cheela spacecraft visits the human one. Although they still need extreme gravity fields to survive, the cheela can now control them precisely enough for both races to see each other face-to-face in safety. The cheela have decided that transferring their technologies, now far advanced of humans', would stunt humanity's development. However the cheela leave clues in several challenging locations, before going their separate ways.
Plot introduction
In Dragon's Egg, Forward describes the history and development of a life form (the Cheela) that evolves on the surface of a neutron star (a highly dense collapsed star, about 20 km in diameter). This is the "dragon's egg" of the title, so named because from Earth it is observed to be near the tail of the constellation Draco ("the dragon"). The Cheela develop sentience and intelligence, despite their relative small size (an individual Cheela has approximately the volume of a sesame seed, but the mass of a human) and an intense gravity field that restricts their movement in the third dimension. Much of the book concerns the biologic and social development of the Cheela; a subplot is the arrival of a human vessel nearby the neutron star, and the eventual contact that is made between the humans and the Cheela. A major problem in this contact is that the Cheela live a million times more quickly than humans do; a Cheela year goes by in about 30 human seconds.
The humans arrive when the Cheela are a savage, backward species, fighting rival clans in a subsistence-level society. Within a few human days, the equivalent of a few thousand Cheela years, the Cheela surpass the humans in technology, and the humans are affectionately called "the Slow Ones".
Forward wrote a sequel to Dragon's Egg, called Starquake, which deals with the consequences of the Cheela developing space travel, and of a seismic disturbance that kills most of the Cheela on the surface of the neutron star.
Development history
Writer Robert L. Forward described being inspired by astronomer Frank Drake's suggestion in 1973 that intelligent life could inhabit neutron stars. Physical models in 1973 implied that Drake's creatures would be microscopic. By the time Forward was outlining the book, newer models indicated that the cheela would be about the size of sesame seeds. Later Forward found an earlier letter in which he discussed the idea of high-gravity life in the Sun with science fiction novelist Hal Clement.
Forward was the scientist and Larry Niven the author in a tutorial on science fiction writing, and later that evening Forward and Niven agreed to collaborate on a novel on aliens on a neutron star. However, Niven soon found himself too busy with Lucifer's Hammer, on which he was already co-writing with Jerry Pournelle. Forward wrote the first draft himself, but several publishers suggested the story should be rewritten by Niven or Pournelle – who were still busy. Finally editor Lester del Rey provided comments that guided Forward through two rewrites, and del Rey then bought the novel. Forward described the work as "a textbook on neutron star physics disguised as a novel".
Publication history
In English:
In other languages:
Literary significance and reception
Quotes from the cover pages:
"This is one for the real science-fiction fan. John Campbell would have loved it." – Frank Herbert
"A gripping and logical account of the evolution of intelligence in an alien race." – Charles Sheffield
"Bob Forward writes in the tradition of Hal Clement's Mission of Gravity and carries it a giant step (how else?) forward." – Isaac Asimov
"Dragon's Egg is superb. I couldn't have written it; it required too much real physics." – Larry Niven
Science fiction critic John Clute wrote that the novel "generates a sense of wonder that is positively joyous", saying it was "a romance of science". Chris Aylott described it as "a minor classic of science fiction – one that shows off both the best and worst elements of hard SF. ... the ideas definitely come first." He found the writing of the human cast dull, but appreciated Forward's ability to share his fascination with the cheela and to create communications between races that lived at vastly different speeds.
Greg Costikyan reviewed Dragon's Egg in Ares Magazine #8 and commented that "Dragon's Egg is interesting because it is the epitome of what "hard" science fiction is all about – extrapolation of the most interesting facets of scientific knowledge and speculation."
Lambourne, Shallis, and Shortland consider that the research and detailed construction of the scenario make Dragon's Egg an excellent example of hard science fiction. Scientist Seth Shostak described the book's science as "fanciful but impossible to dismiss".
John Pierce also regarded Dragon's Egg as hard science fiction at its best, while Forward's later novel Martian Rainbow (1991) was the genre at its worst. Both novels have cardboard human characters, but this does not matter in Dragon's Egg, where the focus is on the deeper personalities of the cheela characters. The novel even makes readers care about the fate of an unsympathetic cheela ruler, whose rejuvenation treatment fails catastrophically. Pierce wrote that the best works of this genre create a literary experience, but one of an unusual kind. Instead of offering a metaphor for a reality the reader already recognizes, they create new realities in which the reader is caught up.
Robert Lambourne regards Forward, especially in Dragon's Egg, as the successor of Hal Clement, whose Mission of Gravity exemplifies the most strongly science-based science fiction. In Lambourne's opinion hard science fiction authors like Clement, Forward and their successors have been relatively few but have strongly influenced both the genre's evolution and the public's perception of the genre.
Awards and nominations
Dragon's Egg won the 1981 Locus Award for First Novel and placed 14th in Locus' SF Novel category.
Sequel
In 1985, Forward published Starquake, a sequel to Dragon's Egg. Lambourne, Shallis and Shortland consider Starquakes scientific background as rigorous as Dragon's Eggs. In this novel, a starquake disrupts cheela civilization, while humans aboard the spacecraft Dragon Slayer deal with their own problems.
See also
Neutron stars in fiction
"Blink of an Eye", an episode of Star Trek: Voyager with a similar premise.
Habitability of neutron star systems
References
Bibliography
External link
1980 American novels
1980 debut novels
1980 science fiction novels
American science fiction novels
Debut science fiction novels
Del Rey books
Fiction about physics
Fiction set around neutron stars
Fiction set in 2032
Fiction set in 2050
Hard science fiction
Novels about ageing
Novels about extraterrestrial life
Novels about spaceflight
Novels about technology
Novels by Robert L. Forward
Novels set in the 2030s
Novels set in the 2050s
Speculative evolution | Dragon's Egg | Biology | 2,596 |
81,863 | https://en.wikipedia.org/wiki/Proportionality%20%28mathematics%29 | In mathematics, two sequences of numbers, often experimental data, are proportional or directly proportional if their corresponding elements have a constant ratio. The ratio is called coefficient of proportionality (or proportionality constant) and its reciprocal is known as constant of normalization (or normalizing constant). Two sequences are inversely proportional if corresponding elements have a constant product, also called the coefficient of proportionality.
This definition is commonly extended to related varying quantities, which are often called variables. This meaning of variable is not the common meaning of the term in mathematics (see variable (mathematics)); these two different concepts share the same name for historical reasons.
Two functions and are proportional if their ratio is a constant function.
If several pairs of variables share the same direct proportionality constant, the equation expressing the equality of these ratios is called a proportion, e.g., (for details see Ratio).
Proportionality is closely related to linearity.
Direct proportionality
Given an independent variable x and a dependent variable y, y is directly proportional to x if there is a positive constant k such that:
The relation is often denoted using the symbols "∝" (not to be confused with the Greek letter alpha) or "~", with exception of Japanese texts, where "~" is reserved for intervals:
(or )
For the proportionality constant can be expressed as the ratio:
It is also called the constant of variation or constant of proportionality.
Given such a constant k, the proportionality relation ∝ with proportionality constant k between two sets A and B is the equivalence relation defined by
A direct proportionality can also be viewed as a linear equation in two variables with a y-intercept of and a slope of k > 0, which corresponds to linear growth.
Examples
If an object travels at a constant speed, then the distance traveled is directly proportional to the time spent traveling, with the speed being the constant of proportionality.
The circumference of a circle is directly proportional to its diameter, with the constant of proportionality equal to .
On a map of a sufficiently small geographical area, drawn to scale distances, the distance between any two points on the map is directly proportional to the beeline distance between the two locations represented by those points; the constant of proportionality is the scale of the map.
The force, acting on a small object with small mass by a nearby large extended mass due to gravity, is directly proportional to the object's mass; the constant of proportionality between the force and the mass is known as gravitational acceleration.
The net force acting on an object is proportional to the acceleration of that object with respect to an inertial frame of reference. The constant of proportionality in this, Newton's second law, is the classical mass of the object.
Inverse proportionality
Two variables are inversely proportional (also called varying inversely, in inverse variation, in inverse proportion) if each of the variables is directly proportional to the multiplicative inverse (reciprocal) of the other, or equivalently if their product is a constant. It follows that the variable y is inversely proportional to the variable x if there exists a non-zero constant k such that
or equivalently, . Hence the constant "k" is the product of x and y.
The graph of two variables varying inversely on the Cartesian coordinate plane is a rectangular hyperbola. The product of the x and y values of each point on the curve equals the constant of proportionality (k). Since neither x nor y can equal zero (because k is non-zero), the graph never crosses either axis.
Direct and inverse proportion contrast as follows: in direct proportion the variables increase or decrease together. With inverse proportion, an increase in one variable is associated with a decrease in the other. For instance, in travel, a constant speed dictates a direct proportion between distance and time travelled; in contrast, for a given distance (the constant), the time of travel is inversely proportional to speed: s × t = d.
Hyperbolic coordinates
The concepts of direct and inverse proportion lead to the location of points in the Cartesian plane by hyperbolic coordinates; the two coordinates correspond to the constant of direct proportionality that specifies a point as being on a particular ray and the constant of inverse proportionality that specifies a point as being on a particular hyperbola.
Computer encoding
The Unicode characters for proportionality are the following:
See also
Linear map
Correlation
Eudoxus of Cnidus
Golden ratio
Inverse-square law
Proportional font
Ratio
Rule of three (mathematics)
Sample size
Similarity
Trairāśika
Basic proportionality theorem
Growth
Linear growth
Hyperbolic growth
Notes
References
Ya. B. Zeldovich, I. M. Yaglom: Higher math for beginners, p. 34–35.
Brian Burrell: Merriam-Webster's Guide to Everyday Math: A Home and Business Reference. Merriam-Webster, 1998, , p. 85–101.
Lanius, Cynthia S.; Williams Susan E.: PROPORTIONALITY: A Unifying Theme for the Middle Grades. Mathematics Teaching in the Middle School 8.8 (2003), p. 392–396.
Seeley, Cathy; Schielack Jane F.: A Look at the Development of Ratios, Rates, and Proportionality. Mathematics Teaching in the Middle School, 13.3, 2007, p. 140–142.
Van Dooren, Wim; De Bock Dirk; Evers Marleen; Verschaffel Lieven : Students' Overuse of Proportionality on Missing-Value Problems: How Numbers May Change Solutions. Journal for Research in Mathematics Education, 40.2, 2009, p. 187–211.
Mathematical terminology
Ratios | Proportionality (mathematics) | Mathematics | 1,159 |
151,828 | https://en.wikipedia.org/wiki/Side%20effect | In medicine, a side effect is an effect of the use of a medicinal drug or other treatment, usually adverse but sometimes beneficial, that is unintended. Herbal and traditional medicines also have side effects.
A drug or procedure usually used for a specific effect may be used specifically because of a beneficial side-effect; this is termed "off-label use" until such use is approved. For instance, X-rays have long been used as an imaging technique; the discovery of their oncolytic capability led to their use in radiotherapy for ablation of malignant tumours.
Frequency of side effects
The World Health Organization and other health organisations characterise the probability of experiencing side effects as:
Very common, ≥ 1⁄10
Common (frequent), 1⁄10 to 1⁄100
Uncommon (infrequent), 1⁄100 to 1⁄1000
Rare, 1⁄1000 to 1⁄10000
Very rare, < 1⁄10000
The European Commission recommends that the list should contain only effects where there is "at least a reasonable possibility" that they are caused by the drug and the frequency "should represent crude incidence rates (and not differences or relative risks calculated against placebo or other comparator)". The frequency describes how often symptoms appear after taking the drug, without assuming that they were necessarily caused by the drug. Both healthcare providers and lay people misinterpret the frequency of side effects as describing the increase in frequency caused by the drug.
Examples of therapeutic side effects
Most drugs and procedures have a multitude of reported adverse side effects; the information leaflets provided with virtually all drugs list possible side effects. Beneficial side effects are less common; some examples, in many cases of side-effects that ultimately gained regulatory approval as intended effects, are:
Bevacizumab (Avastin), used to slow the growth of blood vessels, has been used against dry age-related macular degeneration, as well as macular edema from diseases such as diabetic retinopathy and central retinal vein occlusion.
Buprenorphine has been shown experimentally (1982–1995) to be effective against severe, refractory depression.
Bupropion (Wellbutrin), an anti-depressant, also helps smoking cessation; this indication was later approved, and the name of the drug as sold for smoking cessation is Zyban. Bupropion branded as Zyban may be sold at a higher price than as Wellbutrin, so some physicians prescribe Wellbutrin for smoking cessation.
Carbamazepine is an approved treatment for bipolar disorder and epileptic seizures, but it has side effects useful in treating attention-deficit hyperactivity disorder (ADHD), schizophrenia, phantom limb syndrome, paroxysmal extreme pain disorder, neuromyotonia, and post-traumatic stress disorder.
Dexamethasone and betamethasone in premature labor, to enhance pulmonary maturation of the fetus.
Doxepin has been used to treat angioedema and severe allergic reactions due to its strong antihistamine properties.
Gabapentin, approved for treatment of seizures and postherpetic neuralgia in adults, has side effects which are useful in treating bipolar disorder, essential tremor, hot flashes, migraine prophylaxis, neuropathic pain syndromes, phantom limb syndrome, and restless leg syndrome.
Hydroxyzine, an antihistamine, is also used as an anxiolytic.
Magnesium sulfate in obstetrics for premature labor and preeclampsia.
Methotrexate (MTX), approved for the treatment of choriocarcinoma, is frequently used for the medical treatment of an unruptured ectopic pregnancy.
The SSRI medication sertraline is approved as an antidepressant but delays sexual climax in men, and can be used to treat premature ejaculation.
Sildenafil was originally intended for pulmonary hypertension; subsequently, it was discovered that it also produces erections, for which it was later approved.
Terazosin, an α1-adrenergic antagonist approved to treat benign prostatic hyperplasia (enlarged prostate) and hypertension, is (one of several drugs) used off-label to treat drug induced diaphoresis and hyperhidrosis (excessive sweating).
Thalidomide, a drug sold over the counter from 1957 to 1961 as a tranquiliser and treatment for morning sickness of pregnancy, became notorious for causing tens of thousands of babies to be born without limbs and with other conditions, or stillborn. The drug, though still subject to other adverse side-effects, is now used to treat cancers and skin disorders, and is on the World Health Organization's List of Essential Medicines.
See also
Adverse drug reaction (ADR), a harmful unintended result caused by taking medication
Combined drug intoxication
Conservative management
Drug-drug interaction (DDI), an alteration of the action of a drug caused by the administration of other drugs
Paradoxical reaction, an effect of a substance opposite to what would usually be expected
Pharmacogenetics, the use of genetic information to determine which type of drugs will work best for a patient
Unintended consequences
References
External links
Clinical pharmacology | Side effect | Chemistry | 1,100 |
14,419,104 | https://en.wikipedia.org/wiki/Rivet%20gun | A rivet gun, also known as a rivet hammer or a pneumatic hammer, is a type of tool used to drive rivets. The rivet gun is used on rivet's factory head (the head present before riveting takes place), and a bucking bar is used to support the tail of the rivet. The energy from the hammer in the rivet gun drives the work and the rivet against the bucking bar. As a result, the tail of the rivet is compressed and work-hardened. At the same time the work is tightly drawn together and retained between the rivet head and the flattened tail (now called the shop head, or buck-tail, to distinguish it from the factory head). Nearly all rivet guns are pneumatically powered. Those rivet guns used to drive rivets in structural steel are quite large while those used in aircraft assembly are easily held in one hand. A rivet gun differs from an air hammer in the precision of the driving force.
Rivet guns vary in size and shape and have a variety of handles and grips. Pneumatic rivet guns typically have a regulator which adjusts the amount of air entering the tool. Regulated air entering passes through the throttle valve which is typically controlled by a trigger in the hand grip. When the trigger is squeezed, the throttle valve opens, allowing the pressurized air to flow into the piston. As the piston moves, a port opens allowing the air pressure to escape. The piston strikes against the rivet set. The force on the rivet set pushes the rivet into the work and against the bucking bar. The bucking bar deforms the tail of the rivet. The piston is returned to the original position by a spring or the shifting of a valve allowing air to drive the piston back to the starting position.
Slow-hitting
The slow-hitting gun strikes multiple blows as long as the trigger is held down. The repetition rate is about 2,500 blows-per-minute (bpm). It is easier to control than a one-hit gun. This is probably the most common type of rivet gun in use.
Fast-hitting gun
The fast-hitting gun strikes multiple light-weight blows at a high rate as long as the trigger is held down. These are repeated in the range of 2,500 to 5,000 bpm. The fast-hitting gun, sometimes referred to as a vibrator, is generally used with softer rivets.
Corner riveter
The corner riveter is a compact rivet gun that can be used in close spaces. The rivet is driven at right-angles to handle by a very short barreled driver.
Squeeze riveter
This gun is different from the above rivet guns in that the air pressure is used to provide a squeezing action that compresses the rivet from both sides rather than distinct blows. The squeeze riveter can only be used close to the edge because of the limited depth of the anvil. Once properly adjusted, the squeeze riveter will produce very uniform rivet bucks. The stationary (fixed) jaw is placed against the head and the buck is compressed by the action of the gun.
Pop-rivet gun
A pop rivet gun is made to apply pop rivets to a workpiece, and was invented in 1916 by Hamilton Wylie. This type of rivet gun is unique in its operation, because it does not hammer the rivet into place. Rather, a pop rivet gun will form a rivet in-place.The gun is fed over the rivet's mandrel (a shaft protruding from the rivet head) and the rivet tail is inserted into the work. When the gun is actuated (typically by squeezing the handle), a ball on the rivet's tail is drawn towards the head, compressing a metal sleeve between the ball and the head. This forms another "head" on the opposing side to the workpiece, drawing the work together and holding it securely in place. The mandrel has a weak point that breaks, or "pops" when the riveting process is complete. This style of rivet does not require the use of a bucking bar, because the force applied is away from the work.
See also
Machine
Orbital riveting
Ring binder
Rivet
Riveting machines
References
Further reading
Bureau of Naval Personnel - [US] Navy Training Course Aviation Structural Mechanic S 3 & 2 NavPers 10308-A''. U.S. Navy Training Publications Center, Memphis, Tennessee, 1966, 380 pages
Hand-held power tools
Mechanical hand tools
Metalworking tools
Pneumatic tools
Articles containing video clips | Rivet gun | Physics | 967 |
13,961,495 | https://en.wikipedia.org/wiki/Infor%20XA | Infor XA is commercial ERP software used to control the operations of manufacturing companies. Its prior name, MAPICS, is an acronym for Manufacturing, Accounting and Production Information Control Systems. MAPICS was created by IBM. The product is now owned by Infor Global Solutions.
Originally all MAPICS code ran only on IBM midrange systems like the IBM System 34, 36, 38 and the IBM AS/400, via succeeding versions of the platform - currently IBM i on IBM Power Systems. Early versions were written in IBM RPG, augmented with Control Language programs. IBM's version of SQL is also utilized on the OS integrated database system called Db2 for i . Recent development efforts have added object oriented components written in the Java programming language, which extends a portion of the XA product to servers running Java.
However, the Infor XA product still requires the IBM i operating system. The Java components provide an application runtime which allow user customizations, a rich user interface, an optional web-based interface as well as support for XML interfaces.
Timeline
See also
List of ERP software packages
List of ERP vendors
References
Industrial automation
ERP software
IBM software | Infor XA | Engineering | 237 |
467,428 | https://en.wikipedia.org/wiki/Potential%20gradient | In physics, chemistry and biology, a potential gradient is the local rate of change of the potential with respect to displacement, i.e. spatial derivative, or gradient. This quantity frequently occurs in equations of physical processes because it leads to some form of flux.
Definition
One dimension
The simplest definition for a potential gradient F in one dimension is the following:
where is some type of scalar potential and is displacement (not distance) in the direction, the subscripts label two different positions , and potentials at those points, . In the limit of infinitesimal displacements, the ratio of differences becomes a ratio of differentials:
The direction of the electric potential gradient is from to .
Three dimensions
In three dimensions, Cartesian coordinates make it clear that the resultant potential gradient is the sum of the potential gradients in each direction:
where are unit vectors in the directions. This can be compactly written in terms of the gradient operator ,
although this final form holds in any curvilinear coordinate system, not just Cartesian.
This expression represents a significant feature of any conservative vector field , namely has a corresponding potential .
Using Stokes' theorem, this is equivalently stated as
meaning the curl, denoted ∇×, of the vector field vanishes.
Physics
Newtonian gravitation
In the case of the gravitational field , which can be shown to be conservative, it is equal to the gradient in gravitational potential :
There are opposite signs between gravitational field and potential, because the potential gradient and field are opposite in direction: as the potential increases, the gravitational field strength decreases and vice versa.
Electromagnetism
In electrostatics, the electric field is independent of time , so there is no induction of a time-dependent magnetic field by Faraday's law of induction:
which implies is the gradient of the electric potential , identical to the classical gravitational field:
In electrodynamics, the field is time dependent and induces a time-dependent field also (again by Faraday's law), so the curl of is not zero like before, which implies the electric field is no longer the gradient of electric potential. A time-dependent term must be added:
where is the electromagnetic vector potential. This last potential expression in fact reduces Faraday's law to an identity.
Fluid mechanics
In fluid mechanics, the velocity field describes the fluid motion. An irrotational flow means the velocity field is conservative, or equivalently the vorticity pseudovector field is zero:
This allows the velocity potential to be defined simply as:
Chemistry
In an electrochemical half-cell, at the interface between the electrolyte (an ionic solution) and the metal electrode, the standard electric potential difference is:
where R = gas constant, T = temperature of solution, z = valency of the metal, e = elementary charge, NA = Avogadro constant, and aM+z is the activity of the ions in solution. Quantities with superscript ⊖ denote the measurement is taken under standard conditions. The potential gradient is relatively abrupt, since there is an almost definite boundary between the metal and solution, hence the interface term.
Biology
In biology, a potential gradient is the net difference in electric charge across a cell membrane.
Non-uniqueness of potentials
Since gradients in potentials correspond to physical fields, it makes no difference if a constant is added on (it is erased by the gradient operator which includes partial differentiation). This means there is no way to tell what the "absolute value" of the potential "is" – the zero value of potential is completely arbitrary and can be chosen anywhere by convenience (even "at infinity"). This idea also applies to vector potentials, and is exploited in classical field theory and also gauge field theory.
Absolute values of potentials are not physically observable, only gradients and path-dependent potential differences are. However, the Aharonov–Bohm effect is a quantum mechanical effect which illustrates that non-zero electromagnetic potentials along a closed loop (even when the and fields are zero everywhere in the region) lead to changes in the phase of the wave function of an electrically charged particle in the region, so the potentials appear to have measurable significance.
Potential theory
Field equations, such as Gauss's laws for electricity, for magnetism, and for gravity, can be written in the form:
where is the electric charge density, monopole density (should they exist), or mass density and is a constant (in terms of physical constants , , and other numerical factors).
Scalar potential gradients lead to Poisson's equation:
A general theory of potentials has been developed to solve this equation for the potential. The gradient of that solution gives the physical field, solving the field equation.
See also
Tensors in curvilinear coordinates
References
Concepts in physics
Spatial gradient | Potential gradient | Physics | 983 |
63,998,038 | https://en.wikipedia.org/wiki/Benzoylacetone | Benzoylacetone is the organic compound with the nominal formula C6H5C(O)CH2C(O)CH3. As a 1,3-dicarbonyl, it is a precursor to many heterocycles, such as pyrazoles. It exists predominantly as the enol tautomer C6H5C(OH)=CHC(O)CH3. Its conjugate base (pKa=8.7) forms stable complexes with transition metals and lanthanides.
References
Aromatic ketones
Chelating agents
Ligands
Phenyl compounds | Benzoylacetone | Chemistry | 123 |
3,510,113 | https://en.wikipedia.org/wiki/Salonga%20National%20Park | Salonga National Park (French: Parc National de la Salonga) is a national park in the Democratic Republic of the Congo located in the Congo River basin. It is Africa's largest tropical rainforest reserve covering about 36,000 km2 or . It extends into the provinces of Mai Ndombe, Equateur, Kasaï and Sankuru. In 1984, the national park was inscribed on the UNESCO World Heritage List for its protection of a large swath of relatively intact rainforest and its important habitat for many rare species. In 1999, the site has been listed as endangered due to poaching and housing construction. Following the improvement in its state of conservation, the site was removed from the endangered list in 2021.
Geography
The park is in an area of rainforest about halfway between Kinshasa, the capital, and Kisangani. There are no roads and most of the park is accessible only by river. Sections of the national park are almost completely inaccessible and have never been systematically explored. The southern region inhabited by the Iyaelima people is accessible via the Lokoro River, which flows through the center and northern parts of the park, and the Lula River in the south.
The Salonga River meanders in a generally northwest direction through the Salonga National Park to its confluence with the Busira River.
History
The Salonga National Park was established as the Tshuapa National Park in 1956, and gained its present boundaries with a 1970 presidential decree by President Mobutu Sese Seko. It was registered as a UNESCO World Heritage Site in 1984. Due to the civil war in the eastern half of the country, it was added to the List of World Heritage in Danger in 1999.
The park is co-managed by the Institut Congolais pour la Conservation de la Nature and the World Wide Fund for Nature since 2015. Extensive consultation is ongoing, with the two main populations living within the park; the Iyaelima, the last remaining residents of the park and the Kitawalistes, a religious sect who installed them-self in the park just after its creation. An intense collaboration exists between the park guards and the Iyaelima, as Iyaelima villages are used as guard posts. It is known that bonobo densities are highest around Iyaelima villages which shows that they cause no threat to the park's emblematic species.
Ecology
Located in the center of the Congo Basin, Salonga National Park protects the largest rainforest in Africa and the second largest in the world. The large size and ecological complexity of this rainforest has allowed species and communities to evolve relatively undisturbed. As a result, the national park protects a highly biodiverse and unique ecosystem. Of 735 identified plant species in the southwestern part of the park, 85% rely on animals to disperse their seeds, a process called zoochory.
Many large mammals are found within the park at relatively high densities, including Bongo antelopes, black-crested mangabeys, leopards, and bonobos. The southern region has been the location for studies of bonobos in the wild. There are much higher populations of bonobos near the Iyaelima settlements than elsewhere in the park, apparently because the Iyaelima do not harm them and are playing a strong role in their conservation. Despite hunting pressure, a viable population of forest elephants survive in the park.
Other than bonobo, park is home to several species primates such as Dryas monkey, Thollon's red colobus, Allen's swamp monkey, golden-bellied mangabey, red-tailed monkey, Potto, dwarf bushbaby.
Other mammals in the park include the long-tailed pangolin, giant pangolin, tree pangolin, Congo clawless otter, spotted-necked otter, Angolan kusimanse, aquatic genet, hippopotamus, the African golden cat, red river hog, blue duiker, yellow-backed duiker, sitatunga, bushbuck, water chevrotain and forest buffalo.
There are many bird species present within the park, including the cattle egret, black stork and yellow-billed stork. The Congo peafowl, a threatened bird species endemic to the Congo Basin and the national bird of the Democratic Republic of the Congo, lives in both the primary and secondary forests within the park.
56 fish species have been identified in the park, including the catfishes Clarias buthupogon and Synodontis nigriventris.
African slender-snouted crocodiles are also found within the park.
References
Sources
INCEF - Conservation and Health in Salonga
Wildlife Conservation Society
UNESCO Salonga National Park Site
WCMC Site Data Sheet
National parks of the Democratic Republic of the Congo
World Heritage Sites in the Democratic Republic of the Congo
Protected areas established in 1970
World Heritage Sites in Danger
1970 establishments in Africa
Old-growth forests
Congolian forests | Salonga National Park | Biology | 1,007 |
10,285,944 | https://en.wikipedia.org/wiki/Princeton%20Ocean%20Model | The Princeton Ocean Model (POM) is a community general numerical model for ocean circulation that can be used to simulate and predict oceanic currents, temperatures, salinities and other water properties. POM-WEB and POMusers.org
Development
The model code was originally developed at Princeton University (G. Mellor and Alan Blumberg) in collaboration with Dynalysis of Princeton (H. James Herring, Richard C. Patchen). The model incorporates the Mellor–Yamada turbulence scheme developed in the early 1970s by George Mellor and Ted Yamada; this turbulence sub-model is widely used by oceanic and atmospheric models. At the time, early computer ocean models such as the Bryan–Cox model (developed in the late 1960s at the Geophysical Fluid Dynamics Laboratory, GFDL, and later became the Modular Ocean Model, MOM)), were aimed mostly at coarse-resolution simulations of the large-scale ocean circulation, so there was a need for a numerical model that can handle high-resolution coastal ocean processes. The Blumberg–Mellor model (which later became POM) thus included new features such as free surface to handle tides, sigma vertical coordinates (i.e., terrain-following) to handle complex topographies and shallow regions, a curvilinear grid to better handle coastlines, and a turbulence scheme to handle vertical mixing. At the early 1980s the model was used primarily to simulate estuaries such as the Hudson–Raritan Estuary (by Leo Oey) and the Delaware Bay (Boris Galperin), but also first attempts to use a sigma coordinate model for basin-scale problems have started with the coarse resolution model of the Gulf of Mexico (Blumberg and Mellor) and models of the Arctic Ocean (with the inclusion of ice-ocean coupling by Lakshmi Kantha and Sirpa Hakkinen).
In the early 1990s when the web and browsers started to be developed, POM became one of the first ocean model codes that were provided free of charge to users through the web. The establishment of the POM users group and its web support (by Tal Ezer) resulted in a continuous increase in the number of POM users which grew from about a dozen U.S. users in the 1980s to over 1000 users in 2000 and over 4000 users by 2009; there are users from over 70 different countries. In the 1990s the usage of POM expands to simulations of the Mediterranean Sea (Zavatarelli) and the first simulations with a sigma coordinate model of the entire Atlantic Ocean for climate research (Ezer). The development of the Mellor–Ezer optimal interpolation data assimilation scheme that projects surface satellite data into deep layers allows the construction of the first ocean forecast systems for the Gulf Stream and the U.S. east coast running operationally at the NOAA's National Weather Service (Frank Aikman and others). Operational forecast system for other regions such as the Great Lakes, the Gulf of Mexico (Oey), the Gulf of Maine (Huijie Xue) and the Hudson River (Blumberg) followed. For more information on applications of the model, see the searchable database of over 1800 POM-related publications.
Derivatives and other models
In the late 1990s and the 2000s many other terrain-following community ocean models have been developed; some of their features can be traced back to features included in the original POM, other features are additional numerical and parameterization improvements. Several ocean models are direct descendants of POM such as the commercial version of POM known as the estuarine and coastal ocean model (ECOM), the navy coastal ocean model (NCOM) and the finite-volume coastal ocean model (FVCOM). Recent developments in POM include a generalized coordinate system that combines sigma and z-level grids (Mellor and Ezer), inundation features that allow simulations of wetting and drying (e.g., flood of land area) (Oey), and coupling ocean currents with surface waves (Mellor). Efforts to improve turbulent mixing also continue (Galperin, Kantha, Mellor and others).
Users' meetings
POM users' meetings were held every few years, and in recent years the meetings were extended to include other models and renamed the International Workshop on Modeling the Ocean (IWMO).
Meeting Pages:
List of meetings:
1. 1996, June 10–12, Princeton, NJ, USA (POM96)
2. 1998, February 17–19, Miami, FL, USA (POM98)
3. 1999, September 20–22, Bar Harbor, ME, USA (SigMod99)
4. 2001, August 20–22, Boulder, CO, USA (SigMod01)
5. 2003, August 4–6, Seattle, WA, USA (SigMod03)
6. 2009, February 23–26, Taipei, Taiwan (1st IWMO-2009)
7. 2010, May 24–26, Norfolk, VA, USA (2nd IWMO-2010; IWMO-2010)
8. 2011, June 6–9, Qingdao, China (3rd IWMO-2011; IWMO-2011)
9. 2012, May 21–24, Yokohama, Japan (4th IWMO-2012; )
10. 2013, June 17–20, Bergen, Norway (5th IWMO-2013; )
11. 2014, June 23–27, Halifax, Nova Scotia, Canada (6th IWMO-2014; )
12. 2015, June 1–5, Canberra, Australia (7th IWMO-2015; ).
13. 2016, June 7–10, Bologna, Italy (8th IWMO-2016;).
14. 2017, July 3–6, Seoul, South Korea (9th IWMO-2017;).
15. 2018, June 25–28, Santos, Brazil (10th IWMO-2018;).
16. 2019, June 17–20, Wuxi, China (11th IWMO-2019;).
17. 2022. June 28-July 1, Ann Arbor, MI (12th IWMO-2022).
17. 2023, June 27–30, Hamburg, Germany (13th IWMO-2023).
Reviewed papers from the IWMO meetings are published by Ocean Dynamics in special issues
(IWMO-2009 Part-I, IWMO-2009 Part-II, IWMO-2010, IWMO-2011, IWMO-2012, IWMO-2013, IWMO-2014).
References
External links
POM-WEB page (registration and information)
MPI-POM and Taiwan Ocean Prediction (TOP)
Physical oceanography
Earth sciences
Numerical climate and weather models | Princeton Ocean Model | Physics | 1,405 |
48,550,977 | https://en.wikipedia.org/wiki/Yueh-Lin%20Loo | Yueh-Lin (Lynn) Loo is a Malaysian-born chemical engineer and the Theodora D. '78 and William H. Walton III '74 Professor in Engineering at Princeton University, where she is also the Director of the Andlinger Center for Energy and the Environment. She is known for inventing nanotransfer printing. Loo was elected a Fellow of the Materials Research Society in 2020.
Early life and education
Loo was born in Kuala Lumpur, Malaysia, and later lived in Taipei, Taiwan, where she attended Taipei American School. She moved to the United States to attend the University of Pennsylvania, where she completed bachelor's degrees in chemical engineering and materials science in 1996. She then pursued graduate studies at Princeton University, where she received a Ph.D. in chemical engineering in 2001 after completing a doctoral dissertation titled "Controlled polymer crystallization through block copolymer self-assembly."
Research and career
She worked as a postdoctoral researcher at Bell Laboratories for a year afterward before joining the University of Texas at Austin's Chemical Engineering Department. During her time at Bell Labs, Loo, along with Julia Hsu, accidentally uncovered duplicated figures in two papers by Jan Hendrik Schön, the first of many instances of academic fraud from the researcher. In 2004, she was included by MIT Technology Review on its TR35 list of under-35-year-old innovators for her invention of nanotransfer printing, a technique for printing nanoscale patterns onto plastic surfaces. This technique allows for the creation of organic electronic devices by printing electrical circuit components onto plastic surfaces.
In 2007, Loo joined the faculty of Princeton's Chemical and Biological Engineering Department, where, , she is the Theodora D. '78 and William H. Walton III '74 Professor in Engineering. Her research concerns the periodic structures of block polymers, organic semiconductors, and patterning techniques for plastic electronics.
Loo launched the Princeton E-ffiliates Partnership (E-ffiliates) in 2012.
In 2016 she was appointed director of Andlinger Center for Energy and the Environment.
Loo's research group studies solution-processable organic semiconductors and conductors. She also researches soft lithography. Using derivatives of Hexabenzocoronene Loo's group developed transparent near-UV solar cells for smart windows, which also contain electrochromic polymers that control the window tint.
Loo co-founded Andluca Technologies in 2017.
Awards and honors
2005 Beckman Young Investigators Award
2006 O’Donnell Award from the Academy of Medicine, Engineering and Science of Texas
2008 Alfred P. Sloan Foundation Fellowship
2010 John H. Dillon Medal from the American Physical Society
2011 Appointed to the Global Young Academy
2012 Owens Corning Early Career Award
2013 Elected Fellow of the American Physical Society
2015 Finalist for the Blavatnik Awards for Young Scientists National Awards in the Physical Sciences & Engineering category
2020 Elected Fellow of the Materials Research Society
References
Living people
Chemical engineers
Chemical engineering academics
Malaysian engineers
Malaysian women engineers
Princeton University faculty
Princeton University alumni
University of Pennsylvania School of Engineering and Applied Science alumni
People from Kuala Lumpur
Polymer scientists and engineers
Women materials scientists and engineers
Malaysian emigrants to the United States
Year of birth missing (living people)
21st-century women engineers
Fellows of the American Physical Society
21st-century Malaysian engineers | Yueh-Lin Loo | Chemistry,Materials_science,Technology,Engineering | 672 |
22,685,047 | https://en.wikipedia.org/wiki/List%20of%20astronomical%20catalogues | An astronomical catalogue is a list or tabulation of astronomical objects, typically grouped together because they share a common type, morphology, origin, means of detection, or method of discovery. Astronomical catalogs are usually the result of an astronomical survey of some kind.
0–9
0ES — Einstein Slew Survey, version 0
1A, 2A, 3A — Lists of X-ray sources from the Ariel V satellite
1C — First Cambridge Catalogue of Radio Sources
1ES — Einstein Slew Survey
1FGL, 2FGL — Lists of gamma-ray sources from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope
1RXH — ROSAT HRI Pointed Observations
1RXS — ROSAT All-Sky Bright Source Catalogue, ROSAT All-Sky Survey Faint Source Catalog
1SWASP — SuperWASP
2A — see 1A
2C — Second Cambridge Catalogue of Radio Sources
2E — The Einstein Observatory Soft X-ray Source List
2MASS — Two Micron All Sky Survey
2MASP — Two Micron All Sky Survey, Prototype
2MASSI — Two Micron All Sky Survey, Incremental release
2MASSW — Two Micron All Sky Survey, Working database
2MUCD — Ultracool Dwarfs from the 2MASS Catalog
2MASX — Two Micron All Sky Survey, Extended source catalogue
2MASS-GC (Globular Clusters, I.R.) (2MASS-GC 01 and 2MASS-GC 02 are Hurt 1 and Hurt 2) (source: Bruno Alessi)
3A — see 1A
3C (and 3CR) — Third Cambridge Catalogue of Radio Sources (and revised)
4C — Fourth Cambridge Survey of celestial radio sources
5C — Fifth Cambridge Survey of Radio Sources
6C — Sixth Cambridge Survey of radio sources
7C — Seventh Cambridge Survey
8C — Eighth Cambridge Survey
8pc — 8 parsec listing, all stars within 8 parsec
9C — Ninth Cambridge survey at 15GHz
A
AB — Azzopardi / Breysacher (Wolf-Rayet stars in the Small Magellanic Cloud, SMC)
Abel (globular star clusters)
Abell — Abell catalogue
Abetti — Giorgio Abetti (double stars)
Abt — (for example: open star cluster Abt 1 = Biurakan 4 = Markarian 6 = Stock 7) (at 2:29.6 / +60°39' near the southwestern section of the Heart Nebula in Cassiopeia)
AC — Astrographic Catalogue
A.C. — Alvan Clark (double stars)
Ac / Ack — Agnès Acker (planetary nebulae)
A.G.C. — Alvan Graham Clark (double stars)
AGC — Arecibo General Catalog
ADS — Aitken Double Star Catalogue
AFGL — Air Force Geophysical Laboratory
Ag — Aguero (catalogue of peculiar galaxies, captured during the National Geographic Society — Palomar Observatory Sky Survey) (POSS)
AG, AGK, AGKR — Astronomische Gesellschaft Katalog
AH03 — (star clusters) (source: Bruno Alessi's list)
Al — Allen (planetary nebulae)
Alden — H.L. Alden (double stars)
Alessi — Bruno Sampaio Alessi's catalogue of telescopic asterisms and open star clusters
Alessi / Teutsch — Bruno S. Alessi's and Philipp Teutsch's catalogue of telescopic asterisms and open star clusters
Ali — H. Ali (double stars)
Alicante (for example: open star cluster Alicante 1 at 3:59:18 / +57°14'14", in Camelopardalis). Alicante 1 looks like a chain of dim stars with two relatively bright accompanying stars known as TYC 3725-498-1 and TYC 3725-866-1 (source: Wikisky)
Aller — R.M. Aller (double stars) (Ramón María Aller Ulloa?)
ALS — UBV beta database for Case-Hamburg Northern and Southern Luminous Stars
Alter (open star clusters) (for example: Alter 1 at 0:31:56.9 / +63°09'47" in Cassiopeia) (Alter 1 = King 14 = Alter Cluster)
Alves / Yun (open star clusters)
AM — Arp-Madore catalogue of open and globular star clusters (Halton Arp / Barry F. Madore) (for example: Arp-Madore 1 in Horologium, Arp-Madore 2 in Puppis)
An — Anderson (double stars)
Andrews / Lindsay (AL) (open star clusters) (for example: Andrews-Lindsay 1 at 13:15:16 / -65°55'12" in Musca) (AL 1 is also known as vdB-Hagen 144)
Annis (?)
APM — Automatic Plate Measuring machine
Apriamashvili (open star clusters) (the open star cluster Basel 1 at about one degree WNW of Messier 11 is also known as the Apriamashvili cluster)
Ara — (for example: Ara 2035 at 7:08.8/-24°03' in Canis Major) (S.Aravamudan?)
Arak / Ark — Marat Arsen Arakelian, 1929–1983 (Arakelian Emission Line Objects)
Arce / Goodman (open star clusters)
Archinal — probably Brent A. Archinal (for example: open star cluster Archinal 1 at 18:54:49 / +5°32'54" in Serpens Cauda)
Arg — Friedrich Wilhelm Argelander (double stars)
ARO — Algonquin Radio Observatory
Arp — Atlas of Peculiar Galaxies
ASCC — N.V. Kharchenko, All-Sky Compiled Catalogue, Kinematika Fiz. Nebesn. Tel., 17, part no 5, 409 (2001)
Auner — (for example: open star cluster Auner 1 at 7:04:16 / -19°45'00" in Canis Major) (Auner 1 is the cluster which was "lost" in the disturbing ghost reflection of nearby Alpha Canis Majoris, aka Sirius, this during the Palomar Observatory Sky Survey, POSS)
Av — Antalova (open star clusters) (for example: Antalova 1 at 17:28:55 / -31°34'11' in Scorpius)
Av-Hunter — Aveni / Hunter (open star clusters) (for example: Aveni-Hunter 1 at 23:37:48 / +48°31'12", north of the former constellation Honores Friderici in Andromeda)
AXP — Anomalous X-Ray Pulsar
AZ / AzV — Azzopardi-Vigneau
B
β — S. W. Burnham (double stars)
βpm — Burnham's measures of proper motion stars, 1913 catalogue.
B — Willem H. van den Bos (double stars)
B — E. E. Barnard's List of Dark Nebulae
B2 — Bologna Sky Survey at 408 MHz (9929 radio sources) performed with the Northern Cross Radio Telescope
B3 — The New Bologna Sky Survey at 408 MHz (13354 radio sources) performed with the Northern Cross Radio Telescope
Ba — Barnard (double stars)
Ba — Baade (planetary nebulae)
BAC — Bordeaux Astrographic Catalog
Bail / Bal — R. Baillaud (double stars)
Baize / Baz — Paul Baize (Paul Achille-Ariel Baize, 1901–1995) (double stars)
Balbinot (open and globular star clusters) (for example: globular star cluster Balbinot 1 in Pegasus)
Bar — Barkhatova (open star clusters) (for example: Barkhatova 1, NNW of NGC 7000; the North America Nebula in Cygnus)
BAR — E.E. Barton (double stars)
Bas — Basel (open star clusters) (for example: Basel 1 at about one degree WNW of open star cluster Messier 11 in Scutum) (Basel 1 is also known as the Apriamashvili cluster)
Bat — Hans Battermann, 1860–1922 (double stars)
BAT99 — The Fourth Catalogue of Population I Wolf Rayet stars in the Large Magellanic Cloud
BAY — Uranometria (Bayer designation)
BCVS — Bibliographic Catalogue of Variable Stars
BD — Bonner Durchmusterung
BDS — Burnham Double Star Catalogue
BDS03 (I.R.) — (open star clusters)
BDSB — (for example: open star cluster BDSB 96 at 7:05:18 / -12°19'44")
BDSB03 (I.R.) — (open star clusters)
Be — Bergvall (catalogue of some 400 interacting and distorted galaxies found on glass copies of the ESO Blue Survey)
Be — Berkeley (open star clusters) (104 items)
Be — Bernes (dark nebulae)
Bedin — Luigi Bedin (for example: dwarf spheroidal galaxy Bedin I in Pavo)
Ben — Jack Bennett's catalogue of 152 deep-sky objects in the southern celestial hemisphere, all from the NGC or IC lists, except Ben 47 which is Melotte 105 in Carina, and Ben 72a which is Trumpler 23 in Norma
Bergeron — Joe Bergeron (for example: Bergeron 1 in Cepheus)
BFS — Blitz-Fitch-Stark (for example: BFS 15 in Cepheus)
BH — Van den Bergh / Hagen (open star clusters), see also VdB-Ha
Bhas/Bha — T.P. Bhaskavan (double stars)
Bi — Biurakan (open star clusters)
Bica — (open star clusters)
Bica / Schmitt (open star clusters)
Big — Guillaume Bigourdan (double stars)
Bird — F. Bird (double stars)
Bl — Victor Manuel Blanco (for example: open star cluster Blanco 1 in Sculptor)
Bloch/Blo — M. Bloch (double stars)
Bo — Bochum (open star clusters)
Bo — Bond (double stars)
BoBn — Boeshaar-Bond (planetary nebulae) (for example: BoBn 1, an extragalactic planetary nebula at 0:37 / -13°42' in Cetus)
Bode — (telescopic asterisms)
Boe — Boeger (double stars)
Bogleiv (open star clusters)
Bonatto (open star clusters)
Boo — Samuel Latimer Boothroyd, 1874–1965 (double stars)
Boy — Bowyer (double stars)
BPI — (open star clusters)
BPM / L — Bruce Proper Motion Survey (Luyten)
BPMA — Bordeaux Catalogue (double stars)
Bradley
Brandt — (for example: open star cluster Brandt 1 at 8:09:32 / -47°20'12") ( = Pozzo 1) (very near Gamma Velorum, also known as 'Regor')
Brand / Wouterloot (BW) (open star clusters)
Brey — Breysacher, Large Magellanic Cloud Wolf Rayet stars
BRI — Bj, R, I survey
Briceno (open star clusters) (for example: Briceno 1 at the star 25 Orionis)
Brosch — (open star clusters)
Brso/Bso — Brisbane Observatory, Australia (double stars)
Brt — S.G. Barton (double stars)
Btz — E. Bernewitz (double stars)
Bry — Walter William Bryant (double stars)
BV — Bohm-Vitense (planetary nebulae)
BVD — R. Benavides (double stars)
C
C — Caldwell catalogue (Sir Patrick Moore)
Caballero-Solano — (for example: open star cluster Caballero-Solano 1 at Delta Orionis, also known as the Mintaka cluster)
Calvet — (telescopic asterisms)
Camargo — (open star clusters)
Canali — (telescopic asterisms)
Capo/Cpo — Cape Observatory, South Africa (double stars)
CARMA
Carpenter — (for example: Carpenter 1 at galactic coordinates 213.34 / -12.60) (= BDB 229, = FSR 1086, = MWSC 732)
Carraro — (for example: open star cluster Carraro 1 at 10:37:00 / -58°44'00") (NW of the Eta Carinae Nebula)
CBB — (open star clusters)
CCCP-Cl — (open star clusters)
CCCP-Gp — (open star clusters)
CCCS — Catalogue of Cool Carbon Stars
CCDM — Catalog of Components of Double and Multiple Stars
CCO — Catalogue of Cometary Orbits
CCS — General Catalogue of Cool Carbon Stars
CCS2 — General Catalog of S Stars, second edition
CD / CoD — Cordoba Durchmusterung
CDIMP — Catalogue of Discoveries and Identifications of Minor Planets
CED — Cederblad (gaseous nebula)
CEL — Celescope Catalogue of Ultraviolet Magnitudes
Cezar — (for example: Cezar 6 at galactic coordinates 204.93 / -13.83)
CFBDSIR — Canada-France Brown Dwarfs Survey-InfraRed
CG — Cometary Globule (for example: CG 4 in Puppis, also known as 'God's Hand')
CGCG — Catalogue of Galaxies and Clusters of Galaxies
CGCS — Catalogue of Galactic Cool Carbon Stars
CGO — Catalogue of Galactic O Stars
CGSS — Catalogue of Galactic S Stars
Chaple — (for example: Chaple 1 at galactic coordinates 74.46 / +3.66, which is an asterism called Chaple's Arc, and also Cygnus Fairy Ring, and HD 190466 Group, and Ramakers 20)
Chatard — (telescopic asterisms)
Che — P. S. Chevalier (double stars)
Chereul — (moving groups of stars)
Chiravalle — (for example: Chiravalle 1 in Hercules, at galactic coordinates 75.25 / +27.91, which is an asterism called Candle and Holder).
Chupina — (Chupina objects 1 to 5 are located at and near open star cluster Messier 67 in Cancer)
CIO — Catalog of Infrared Observations
CLUST — (open star clusters)
CMC — Carlsberg Meridian Catalogue
Cn — Cannon (planetary nebulae) (Cn1 / Cn2 / Cn3)
Cog — Cogshall (double stars)
Col — Collins (double stars)
Com — G. C. Comstock (double stars)
Cop — Copeland (double stars)
Coro/Coo — Cordoba Observatory, Argentina (double stars)
CoRoT — CoRoT Catalogue
CoRoT-Exo — CoRoT Catalogue
Cou — Paul Couteau (double stars)
CP — Cambridge Pulsar
CPC — Cape Photographic Catalogue
CPD — Cape Photographic Durchmusterung
Cr — Collinder (open star clusters) (Per Collinder)
Crinklaw — (telescopic asterisms)
CRL — Cambridge Research Laboratory Sky-Survey
Cruls/Cru — L. Cruls (double stars)
CSI — Catalog of Stellar Identifications
CSV — Catalog of Suspected Variables
CSS — General Catalogue of S Stars
Cz — Czernik (open star clusters)
D
D — James Dunlop (A catalogue of nebulae and clusters of stars in the southern hemisphere, observed at Parramatta in New South Wales)
DA — Dominion Observatory List A
Danjon — Andre Danjon (double stars)
Danks — (open star clusters) (for example: Danks 1 & 2, located near the northeastern Centaurus section of the Coalsack Nebula)
Dawes — W.R. Dawes (double stars)
δ — B.H. Dawson (double stars)
DBSB03, I.R. — (open star clusters)
DB2000 (Dutra-Bica 2000, I.R.) (open star clusters)
DB2001 (Dutra-Bica 2001, I.R.) (open star clusters)
DC — (open star clusters)
DCld — A catalogue of southern dark clouds
DDO — David Dunlap Observatory (Dwarf Galaxies)
DeHt — Dengel-Hartl (planetary nebulae) (for example: DeHt 1 at 5:55 / -22°54' in Lepus)
Dem — Ercole Dembowski (double stars)
DENIS — Deep Near Infrared Survey of the Southern Sky
DENIS-P — Deep Near Infrared Survey, Provisory designation
Desvoivres — (telescopic asterisms)
DHW — Dengel-Hartl-Weinberger (planetary nebulae)
Dias — Wilton S. Dias, UNIFEI (open star clusters)
Dick — J. Dick (double stars)
Djorg — Stanislav George Djorgovski (globular star clusters) (for example: Djorgovski 1 in Scorpius)
Dju — P. Djurkovic (double stars)
DM — Durchmusterung
BD — Bonner Durchmusterung
CD / CoD — Cordoba Durchmusterung
CPD — Cape Photographic Durchmusterung
DN — Duus-Newell (Catalogue of Southern Groups and Clusters of Galaxies) (Alan Duus / Barry Newell)
DnB — Open Source (nebulae)
DO — Dearborn Observatory
Do — Dolidze (open star clusters) (57 items)
Dob — A.W. Doberck (double stars)
Dom — Jean Dommanget (double stars)
Don — H.F. Donner (double stars)
Donatiello — Giuseppe Donatiello (for example: dwarf spheroidal galaxy Donatiello I in Andromeda)
Doo — Eric Doolittle (double stars)
DoDz — Dolidze-Dzimselejsvili (open star clusters) (11 items)
Dorpat — Dorpat Observatory, Estonia
DR — Downes and Rinehart microwave sources
Du — Duner (double stars)
Δ — James Dunlop (double stars)
Dutra-Bica (open star clusters)
DWB — Dickel, Wendker, Bieritz (A catalogue of optically visible HII regions in the Cygnus X region)
Dwingeloo — Dwingeloo Obscured Galaxy Survey (DOGS) (for example: Dwingeloo 1 and Dwingeloo 2 in Cassiopeia)
E
E — (for example: globular star cluster E 3 at 9:20:59 / -77°16'57", in Chamaeleon) (source: Bruno Alessi's and Wilton Dias's lists)
EC — Edinburgh-Cape Blue Object Survey
Edg — D.W. Edgecomb (double stars)
[EG97] — Eckart + Genzel, 1997 (Stars close to Sagittarius A*, like [EG97]S2.)
Egb — Egbert (double stars)
EGB — Ellis-Grayson-Bond (planetary nebulae)
Eggen — Olin J. Eggen (double stars)
EGGR — Eggen-Greenstein proper motion star
Elosser — (telescopic asterisms)
EMP — Ephemerides of Minor Planets
Eng — Engelmann (double stars)
EPIC — Ecliptic Plane Input Catalog
Escorial — (open star clusters)
ESO — European Southern Observatory Catalog, ESO/Uppsala catalog
Esp — T. E. H. Espin (double stars)
Es/Birm — Espin/Birmingham (catalogue of red stars)
F
F — Fath — Edward Arthur Fath, 1880–1959 (for example: galaxy Fath 703, aka NGC 5892, in Libra)
Fa — Fairall (Anthony Patrick Fairall, 1943–2008)
FCC — Fornax Cluster Catalogue
Fei — Feinstein (open star clusters) (for example: Feinstein 1 at 11:05:56 / -59°49'00" in Carina)
Feibelman (for example: open star cluster Feibelman 1 near 'The Revenante of the Swan' 34-P Cygni)
Feigelson (for example: open star cluster Feigelson 1 at 11:59:51 / -78°12'27", in Chamaeleon, at the binary star Epsilon Chamaeleonis)
Ferrero (telescopic asterisms)
Φ — W.S. Finsen (double stars)
Fg — Fleming (planetary nebulae), for example: Fleming 1
FK4 — Fourth Fundamental Catalogue
FK5 — Fifth Fundamental Catalogue
Fle — J.O. Fleckenstein (double stars)
FLM — Historia coelestis Britannica (Flamsteed designation)
For — L. Forgeron (double stars)
Fox — Philip Fox (double stars)
French — Sue French (from Sky and Telescope)
Fr — Frolov (open star clusters) (for example: Frolov 1 at 23:57:25 / +61°37'48" in Cassiopeia)
Franz — J. Franz (double stars)
Frh — R. Furuhjelm (double stars)
Frk — W.S. Franks (double stars and colours of stars) (probably William Sadler Franks, published a catalogue of the colours of 3890 stars)
FSC — Faint Source Catalogue
FSR — Froebrich-Scholz-Raftery, I.R. (open and globular star clusters) (for example: globular star cluster FSR 1758 in Scorpius)
Fur — H.Furner (double stars)
G
G — Lowell Proper Motion Survey (Giclas)
GD — Lowell Proper Motion Survey (Giclas dwarf)
GR* — Lowell Proper Motion Survey (Giclas red star)
HG — Lowell Proper Motion Survey (Giclas Hyades)
Gale — W.F. Gale (double stars)
Gallo — J. Gallo (double stars)
GAn — G. Anderson (double stars)
Gaia catalogues (general purpose)
Gaia DR1
Gaia DR2
Gaia EDR3
Gaia DR3
GC — General Catalogue of Nebulae and Clusters
GC (Boss) — Boss general catalogue of 33342 stars
GCRV — General Catalogue of Stellar Radial Velocities
GCTP — General Catalogue of Trigonometric Parallaxes
GCVS — General Catalog of Variable Stars
Giclas — Henry L. Giclas (double stars)
Gl / GJ — Gliese–Jahreiß catalogue or Gliese–Jahreiß catalogue
GJJC — Gillett-Jacoby-Joyce-Cohen (planetary nebulae)
Gli — J.M. Gilliss (double stars)
GLIMPSE — (together with Mercer in the list of 10978 star clusters)
Glp — S. de Glasenapp (double stars)
GM — Gyulbudaghian-Maghakian (planetary nebulae)
Gol — H. Goldschmidt (double stars)
GOS — Galactic O Star Catalogue
GOSSS — Galactic O-Star Spectroscopic Survey
Goyal — A.N. Goyal (double stars)
Graham (for example: open star cluster Graham 1 at 10:56:32 / -63:01:04 in Carina)
Gr — Grant (double stars)
Grasdalen (open star clusters)
GR — Gibson Reaves (for example: Gibson Reaves 8 (GR 8) (galaxy) in Virgo) (Gibson Reaves, 1923–2005)
GRB — Gamma Ray Burst
Grindlay (globular star clusters) (for example: Grindlay 1 in Scorpius, at 17:32.0 / -33°50')
GRO — Gamma Ray Observatory (NASA — Compton)
Groombridge (Stephen Groombridge, 1755–1832)
GSC — Guide Star Catalog
GSC2 / GSC II — Guide Star Catalog II
GSPC — Guide Star Photometric Catalog
GSPC2 — Guide Star Photometric Catalog, 2nd
Gsh — J. Glaisher (double stars)
GΣ — G. Struve (double stars)
Gtb — K. Gottlieb (double stars)
Gui — J. Guillaume (double stars)
Gum — Gum catalog of emission nebulae
H
h — John Herschel (double stars)
H — Haro (planetary nebulae)
H — Harvard (open star clusters)
H — William Herschel (double stars)
HA — ? (for example: galaxy HA 85 in Telescopium, see chart 26 in Wil Tirion's Sky-Atlas 2000.0) (however, chart 435 in Uranometria 2000.0, Volume 2, 1987 edition, shows this object as ESO 183-G30)
Haf — Haffner (open star clusters)
Hall — Asaph Hall (double stars)
HAT-P — HATNet Project, Hungarian Automated Telescope Network (search for extrasolar planets)
HATS - HATNet Project, southern hemisphere.
HaTr — Hartl-Tritton (planetary nebulae)
Haufen — (for example: Haufen A in Cetus, at 1h 08.9m / -15° 25' (2000.0), which is, according to Sky Catalogue 2000.0, Volume 2, the same as Abell 151)
Hav/Moffat — Havlen-Moffat (open star clusters)
Hb — Hubble (planetary nebulae)
HC — Howell-Crisp (planetary nebulae)
HCG — Hickson Compact Group
HCWils — H.C. Wilson (double stars)
HD — Henry Draper Catalogue
HDE — Henry Draper Extension
HDEC — Henry Draper Extension Charts
HdO — Harvard Observatory USA, and stations elsewhere (double stars)
HDW — Hartl-Dengel-Weinberger (planetary nebulae)
Hdz — Harvard Zone Catalogues (double stars)
HE — Hamburg/ESO Survey
He — Henize (planetary nebulae)
Hen — Henize Catalogues of Hα-Emission Stars and Nebulae in the Magellanic Clouds
Hf — Hoffleit (planetary nebulae)
HFG — Heckathorn-Fesen-Gull
HH — Herbig-Haro object
HIC — Hipparcos Input Catalogue
HIP — Hipparcos Catalogue
HIPASS — HI Parkes All-Sky Survey
Hld — E.S. Holden (double stars)
Hlm — E. Holmes (double stars)
Hln — Frank Holden (double stars)
HN — William Herschel's 1821 catalogue (double stars)
Ho — Hogg (open star clusters)
Ho — G.W.Hough (double stars)
Holmberg — Erik Holmberg (dwarf irregular galaxies)
Hooke — Robert Hooke (double stars)
Howe — H.A. Howe (double stars)
HP — Haute Provence (globular star clusters) (for example: HP 1 in Ophiuchus, at 17:31.1 / -29°59')
HR — Bright Star Catalogue (Harvard Revised Catalogue)
Hrg — L. Hargrave (double stars)
Hrr — Harrington (telescopic asterisms)
HΣ — Hermann Struve (double stars)
HS — Hamburg Survey (quasars and blue stars)
HSC — Hubble Source Catalog (lists of sources from the Hubble Space Telescope)
Hst — C.S. Hastings (double stars)
Hu — Humason (planetary nebulae)
Hu — W.J. Hussey (double stars)
Hurt — Robert Hurt (for example: globular star cluster Hurt 2, aka 2MASS-GC02 in Sagittarius)
Huygens — Christiaan Huygens (double stars)
HV — Harvard Variable
HVGC — Hyper Velocity Globular Cluster (for example: HVGC-1 in the supergiant elliptical galaxy Messier 87 in Virgo)
HVS — HyperVelocity Stars
Hynek — J. Allen Hynek (double stars)
Hz — Wulff D. Heintz (double stars)
Hzg — E. Hertzsprung (double stars)
I
I — Robert Thorburn Ayton Innes (R.T.A. Innes, 1861–1933) (double stars)
IC — Index Catalogue
IC I — Index Catalogue I
IC II — Index Catalogue II
IDS — Index Catalogue of Visual Double Stars
IGR — Integral Gamma-Ray source
IPHAS — The INT Photometric Hα Survey of the Northern Galactic Plane
IRAS — Infrared Astronomical Satellite
IRS — International Reference Star
Isk — Iskudarian (open star clusters) (for example: Iskudarian 1 in the northern section of the rhombus β, γ, δ, and ζ Lyrae)
Isserstedt (telescopic asterisms)
IsWe — Ishida-Weinberger (planetary nebulae)
Ivanov (open star clusters)
J
J — Robert Jonckheere's catalogue of double star observations (see for an article about it)
Ja — Jacoby (planetary nebulae) (for example: Jacoby 1 at 15:23 / +52°14' in Boötes)
JaFu — Jacoby-Fullton (planetary nebulae)
JAn — John A. Anderson (double stars)
Jc — William Stephen Jacob (double stars)
Jef — H.M. Jeffers (double stars)
Jn — Jones (planetary nebulae) (for example: Jones 1 at 23:36 / +30°28' in Pegasus)
JnEr — Jones-Emberson (planetary nebulae) (for example: Jones-Emberson 1 in Lynx, also known as the Headphone nebula)
Jo — Jones (double stars)
Johansson — (open star clusters) (for example: Johansson 1 at 15:46:20 / -52:22:54 in Norma)
Joy — Alfred Harrison Joy (double stars)
JP11 – a 1978 catalog compiling photometric measurements in Harold Johnson's 11-color photometric system
Jsp — Morris Ketchum Jessup (double stars)
Juchert — (open star clusters)
Juchert-Saloranta (telescopic asterisms)
JW — Jones' & Walker's list of stars near the Orion Nebula.
K
K — Lubos Kohoutek (planetary nebulae)
Ka — Valentina Karachentseva (dwarf galaxies)
Karhula — (for example: open star cluster Karhula 1 near planetary nebula Messier 76 in Perseus)
— K2 (Kepler extended mission) catalog
KELT — Kilodegree Extremely Little Telescope (search for extrasolar planets)
Kemble — Father Lucian Kemble (asterisms which could be observed through binoculars, for example: Kemble 1, aka Kemble's Cascade in Camelopardalis)
Kepler — Kepler catalog
Kes — Kesteven (supernova remnants). For example: Kesteven 79
K / Kg — Ivan R. King (open star clusters)
KGZ — Catalogue de Zimmerman
Kharchenko (for example: open star cluster Kharchenko 1 at 6:08:48 / +24:19:54 near or at Messier 35 in Gemini)
KIC — Kepler Input Catalog
Kim — Dongwon Kim (for example: globular star cluster Kim 2 in Indus)
KjPn — Kazaryan-Parsamyan (planetary nebulae)
Klemola (for example: Klemola 44 galaxy cluster in Sculptor) (? — Arnold Richard Klemola, 1931–2019)
KnFs — Kinman-Feast-Lasker (planetary nebulae)
Knott / Kn — G. Knott (double stars)
KOI — Kepler Object of Interest
Kontizas (for example: Kontizas 953 in Dorado) (in the Large Magellanic Cloud)
Koposov (open and globular star clusters) (for example: globular star clusters Koposov 1 and Koposov 2 in Virgo and Gemini)
Kr — A.Kruger (double stars) (probably Karl Nikolaus Adalbert Krueger, 1832–1896)
Kron — (globular star clusters) (for example: Kron 3 in Tucana)
Kronberger — (for example: open star cluster Kronberger 1 at 5:28:20 / +34°46'52", aka Alicante 12, in Auriga)
Kru — E.C. Kruger (double stars)
Ku — F. Kustner (double stars)
KUG — Kiso Survey for Ultraviolet-excess Galaxies
Kui — Gerard P. Kuiper, 1905–73 (double stars)
KUV — Kiso observatory, UV-excess object
L
L / BPM — Bruce Proper Motion Survey (Luyten)
La — Langley (double stars)
Lac — N. de Lacaille, 1713–62 (double stars)
Lac — Catalog of Nebulae of the Southern Sky (Lacaille)
Lac I — Nebulae
Lac II — Nebulous Star Clusters
Lac III — Nebulous Stars
Laevens — Benjamin P. M. Laevens (globular clusters and dwarf galaxies), for example: Laevens 1 in Crater, Laevens 2 in Triangulum (Triangulum II), Laevens 3 in Delphinus.
Lal — F. de Lalande (double stars)
Lam — J. von Lamont (double stars)
λ (Lambda) — (mentioned in T.W.Webb's Celestial Objects for Common Telescopes, Volume 2: The Stars, pages 285–319: Index of Double Stars, Epoch 2000)
Printed examples from the 'Lambda' catalogue: λ 32 (RA 3:47.9), λ 88 (RA 7:48.9), λ 91 (RA 7:55.7), λ 96 (RA 8:12.5), λ 108 (RA 9:0.3), λ 115 (RA 9:37.1), λ 140 (RA 11:56.7), λ 176 (RA 13:20.5), λ 228 (RA 15:23.2), λ 249 (RA 15:47.6), λ 316 (RA 17:0.4), λ ? (RA 17:6.4), λ 320 (RA 17:12.2), λ 342 (RA 17:53.3). All examples are located in the southern celestial hemisphere. The 'Lambda' catalogue is related to T.J.J.See's catalogue of double stars.
LAMOST — Large Sky Area Multi-Object Fibre Spectroscopic Telescope (Guo Shoujing Telescope)
Latham — (for example: Latham 1 at 13:10:50 / +30°28'36" in Coma Berenices)
Latysev — (open star clusters)
Lau — H.E. Lau (double stars)
LBN — Lynds' Catalogue of Bright Nebulae
Lbz — P. Labitzke (double stars)
LDN — Lynds' Catalogue of Dark Nebulae
LDS — Luyten Double Star catalogue
LEDA — Lyon-Meudon Extragalactic Database
Lederman — (telescopic asterisms)
Le Gentil — (for example: Le Gentil 3 in Cygnus, at 21:08 / +51°40') (dark nebula)
Leon — Frederick C. Leonard (double stars)
Lewis — Thomas Lewis (double stars)
LFT — Luyten Five-Tenths catalogue
LG11 — Lépine & Gaidos 2011, bright M dwarfs
LGG — Lyons Groups of Galaxies
– Local Group Galaxy Survey
LGS — (for example: dwarf galaxy LGS 3 in Pisces, also known as the Pisces Dwarf)
LHA — Lamont-Hussey Alpha
LHS — Luyten Half-Second catalogue
Liller (globular star clusters) (for example: Liller 1 in Scorpius)
Lo — Lars Olof Loden (open star clusters)
Lo — Longmore
Loiano — (for example: open star cluster Loiano 1 at 19:58:21 / +32°32'42" in Cygnus)
Lorenzin — Tomm Lorenzin (telescopic asterisms)
LoTr — Longmore-Tritton (planetary nebulae)
LP — Luyten-Palomar Survey
LPM — Luyten Proper-Motion Catalogue
LPO — La Plata Observatory, Argentina
LS — either of two "Luminous Stars" catalogues; see LSN and LSS, below
LS — Lensed Star (LS 1 = 'Icarus' in Leo) (see MACS J1149 Lensed Star 1)
LSA — Lundstrom-Stenholm-Acker (planetary nebulae)
LSN — Luminous Stars in the Northern Milky Way
LSPM — LSPM catalog — Lépine-Shara Proper Motion catalog
LSR — Lepine-Shara-Rich catalogue
LSS — Luminous Stars in the Southern Milky Way
LTT — Luyten Two-Tenths catalogue
Luginbuhl-Skiff — (for example: open star cluster Luginbuhl-Skiff 1 at 6:14:48 / +12°52'24", slightly east of open star cluster NGC 2194 in Orion)
Luhman — (for example: Luhman 16 in Vela)
Luy — W.J. Luyten (double stars)
Lv — Francis Preserved Leavenworth (double stars)
Ly — Lynga (open star clusters)
M
M — Catalog of Nebulae and Star Clusters (Messier object)
M — Minkowski (planetary nebulae)
Ma — J.H. Madler (double stars)
Mac — Maclear (double stars)
MACS — Massive Cluster Survey or Magellanic Catalogue of Stars
MACHO — MACHO Project lensing events (Massive Compact Halo Object)
MACHO-LMC — MACHO Project Large Magellanic Cloud Microlensing
MACHO-SML — MACHO Project Small Magellanic Cloud Microlensing
Maffei — Paolo Maffei (for example: galaxies Maffei 1 and Maffei 2 in Cassiopeia)
Mailyan — (for example: Mailyan 44, aka Holmberg I / DDO 63 / UGC 5139, at 9h 40.5m / +71° 11' in Ursa Major)
Malin — David Malin (for example: the largest galaxy known; Malin 1 in Coma Berenices)
Mamajek (open star clusters) (for example: Mamajek 1 at 8:42:06 / -79°01'38" in Chamaeleon, also known as η Chamaeleontis cluster or η Chamaeleontis association)
Markov (telescopic asterisms) (for example: Markov 1 in Hercules)
MAXI — Monitor of All-sky X-ray Image
Mayall — Nicholas Mayall (for example: globular star cluster Mayall II orbiting Messier 31, the Andromeda galaxy)
Mayer (open star clusters)
McC — McCormick Observatory Catalog
MCG — Morphological Catalogue of Galaxies
MCW — Morgan, Code, and Whitford
Me — Merrill (planetary nebulae)
Mel — Melotte Catalogue of open star clusters (Philibert Jacques Melotte)
Mercer (for example: globular star cluster Mercer 3 in Scutum)
MGC (globular star clusters) (for example: MGC1 in Pisces)
Mh — O.M. Mitchel (double stars)
Mil — J.A. Miller (double stars)
Miller (open star clusters) (for example: Miller 1 at 9:25:42 / -53°14'00", near the variable star GL Velorum, in Vela)
Milb — W. Milburn (double stars)
MlbO — Melbourne Observatory, Australia (double stars)
Mlf — Frank Muller (double stars)
Mlr — Paul Muller (double stars)
Moffat (open star clusters) (for example: Moffat 1 at 16:01:30 / -54°07'00" in Norma)
Moitinho (open star clusters) (for example: Moitinho 1 at 8:19:17 / -45°12'30", southwest of the Gum Nebula, in Vela)
MPC — Minor Planet Circulars contain astrometric observations, orbits and ephemerides of both minor planets and comets
Mrk — Benjamin "Benik" Egishevitch Markarian (open star clusters and galaxies; the Markarian galaxies)
MSH — Mills, Slee, Hill — Catalog of Radio Sources
Muzzio (open star clusters) (for example: Muzzio 1 at 8:57:12 / -47°46'00" in Vela)
MW — Mandel-Wilson Catalogue of Unexplored Nebulae, not in SIMBAD yet
MWC – (1933) Class O, B and A stars with bright hydrogen lines
MWP — Motch-Werner-Pakull (planetary nebulae)
MyCn — Mayall-Cannon (planetary nebulae)
Mz — Menzel (planetary nebulae)
N
N — (for example: N 164 nebula in Dorado)
Na — Nassau (planetary nebulae)
Naillon — (telescopic asterisms) (source: Bruno Alessi's list)
N30 — Catalog of 5,268 Standard Stars Based on the Normal System N30
Neckerman (telescopic asterisms) (for example: Neckerman 1, aka Kemble 2 "Little Cassiopeia").
NED — NASA/IPAC Extragalactic Database
Negueruela — (Ignacio Negueruela)
NeVe — Neckel-Vehrenberg (planetary nebulae)
New — ? (galaxies)
New 1 in Cetus (source: The Deep-Sky Field Guide to Uranometria 2000.0, Cragin-Lucyk-Rappaport, chart 262).
New 5 in Sagittarius (thus mentioned on chart 22 of Wil Tirion's Sky-Atlas 2000.0, mentioned as ESO 285-G7 on charts 411 and 412 in Uranometria 2000.0 Volume 2, 1987 edition).
New 6 in Indus (chart 23 in Tirion's Sky-Atlas 2000.0, chart 413 in the 1987 edition of Uranometria 2000.0, Volume 2) (as ESO 287-G13)
NGC — New General Catalogue
NGTS — Next-Generation Transit Survey (extrasolar planets)
NHICAT — Northern HIPASS Catalog
NLTT — New Luyten Two-Tenths Catalogue
NOMAD — The Naval Observatory Merged Astrometric Dataset (NOMAD)
NStars — Nearby Stars Database
NSV — New Catalogue of Suspected Variable Stars
NZO — New Zealand Observatory (double stars)
O
O — O'Neal (open star clusters)
OCL — Open Clusters
OEC — Open Exoplanet Catalogue
OGLE — Optical Gravitational Lensing Experiment
Ol — Charles Pollard Olivier (double stars)
Opik — Ernst J. Opik (double stars)
OSC — Open Supernova Catalog
OΣ — Otto Struve, Pulkovo Catalogue, 1843 (double stars)
OΣΣ — Otto Struve, Pulkovo Catalogue Supplement, 1843 (double stars)
OSS — Ohio Sky Survey
OTC — Open TDE Catalog
OTS — Oasa-Tamura-Sugitani
Ou — Nicolas Outters (for example: Ou 4, the 'Squid Nebula' in Cepheus) (see APOD — Astronomy Picture Of the Day — July 18, 2014).
P
P — Perrine (double stars)
PAL — Palomar Globular Clusters (15 globular clusters discovered on the Palomar Observatory Sky Survey plates)
Par — Parkhurst (double stars)
PB — Peimbert-Batiz (planetary nebulae)
PC — Peimbert-Costero (planetary nebulae)
PACWB — Catalogue of Particle-Accelerating Colliding-Wind Binaries
Pe — Perek (planetary nebulae)
Perr — Perrotin (double stars)
Perry — Perry (double stars)
PG — Palomar-Green (catalogue of ultraviolet excess stellar objects)
PGC — Principal Galaxies Catalogue
PH — Planet Hunters
PHL — Palomar-Haro-Luyten catalogue
Pi — Pismis (Paris Pişmiş, 1911–1999) (catalogue of 22 open star clusters and 2 globular star clusters)
PK — Catalogue of galactic planetary nebulae (Perek-Kohoutek)
PKS — Parkes Catalogue of Radio Sources
Platais — Imants Platais' catalogue of open star clusters
Plq — Paloque (double stars)
PLX — General Catalogue of Trigonometric Stellar Parallaxes and Supplement (Jenkins, Yale University)
PM — Preite Martinez (planetary nebulae)
PMC — Tokyo Photoelectric Meridian Circle Catalog
PN — See PNG
PNG — Strasbourg-ESO Catalogue of Galactic Planetary Nebulae
Pol — Pollock (double stars)
Pou — Pourteau (double stars)
PPM — Positions and Proper Motions Star Catalogues
Pri — Pritchett (double stars)
PrO — Perth Observatory, Australia (double stars)
Prz — Przbyllok (double stars)
Ps — Francis G. Pease (planetary nebulae) (for example: Pease 1 in the globular cluster Messier 15, Pegasus)
PSR — Pulsating Source of Radio (pulsars)
PTFO — Palomar Transient Factory
Ptt — Pettit (double stars)
Pu — Purgathofer (planetary nebulae)
PuWe — Purgathofer-Weinberger (planetary nebulae)
Pz — Piazzi (double stars)
Q
Q (?) — (for example: galaxy Q 6188 at 0:48.6 / -12:44 in Cetus) (mentioned on charts 261 / 262 in Uranometria 2000.0 Volume 2, 1987 edition) (according to Wolfgang Steinicke and Richard Jakiel of the book Galaxies and How to Observe Them, this galaxy (Q 6188) is also catalogued as Mrk 960 and PGC 2845)
QES — QATAR Exoplanet Survey
QSO — Revised and Updated Catalog of Quasi-stellar Objects
QZM — (for example: QZM 2 at galactic coordinates 78.12 / +3.63) (J2000 — 20:14:26 / +41°13'28") (QZM 2 = Froebrich 116, = SUH 151)
R
R — Radcliffe Observatory (RMC — Radcliffe Observatory Magellanic Clouds Catalogue)
R — Rose (Rose Catalogue of Southern Clusters of Galaxies)
R — H.C. Russell (double stars)
Raab (open star clusters)
RAFGL — Revised Air Force Geophysical Laboratory (four color infrared sky survey)
Raymond — (telescopic asterisms)
RBC — Revised Bologna Catalogue (for example: globular cluster RBC EXT8 in Messier 31; the Andromeda Galaxy)
RBS — Rosat Bright Survey (bright X-ray sources)
RC — Reference Catalogue
RC2 — Reference Catalogue, 2nd edition
RC3 — Reference Catalogue, 3rd edition
RCW — Rodgers-Campbell-Whiteoak, a catalogue of Hα-emission regions in the southern Milky Way
RECONS — Research Consortium on Nearby Stars
Reiland — (for example: open star cluster Reiland 1 at 23:04:45 / +60°04'40")
Reinmuth — (galaxies) (for example: Reinmuth 80 in Virgo) (NGC 4517A)
Renou (telescopic asterisms)
Reyle-Robin — (open star clusters, I.R.)
Richaud — Jean Richaud, 1633–93 (double stars)
Riddle — (open star clusters / telescopic asterisms)
Rmk — C.L.C. Rumker (double stars)
RMM — (for example: open star cluster RMM 1 at 12:12:20 / -63°15'31")
RNGC — Revised New General Catalogue
Ro — Curt Roslund (open star clusters)
Roberts — (protoplanetary nebulae)
Roe — Edward Drake Roe, 1859–1929 (double stars)
Roman-Lopes — (open star clusters, I.R.)
Ross — Ross Catalogue of New Proper Motion Stars (Frank Elmore Ross)
ROT — Catalogue of Rotational Velocities of the Stars
RSA — Revised Shapley-Ames Catalogue
RSGC — Red Super Giant Cluster (for example: RSGC 3 at 18:45:20 / -3°24'43")
RST — Catalogue of southern double stars (Richard Alfred Rossiter, 1886–1977)
Ru — Jaroslav Ruprecht (open star clusters)
RX — ROSAT observations
S
S — James South (double stars)
Sa — Sanduleak (planetary nebulae)
SA — Sandqvist (dark nebulae) (for example: Sandqvist 169 near Alpha Centauri)
SACS — Second Astrolabe Catalogue of Santiago
Saloranta — Jaakko Saloranta (telescopic asterisms)
SAO — Smithsonian Astrophysical Observatory Star Catalog
Saurer — (for example: the open star cluster Saurer 1 at 7:18:18 / +1°53'12" in Canis Minor)
SaWe — Sanduleak-Weinberger (planetary nebulae)
SAX — Satellite per Astronomia a raggi X (BeppoSAX satellite)
SC — Slough catalogue ("Observations of Nebulae and Clusters of Stars, made at Slough, with a Twenty-Feet Reflector, between the years 1825 and 1833" by John Herschel; 2306 entries)
Schb — John Martin Schaeberle (double stars)
Schj — Hans Schjellerup (double stars)
Schoenberg — (for example: Schoenberg 205-6 at 6:37.1 / +10°21')
Schuster — (for example: open star cluster Schuster 1 at 10:04:39 / -55°51'29" in Vela)
SCM — Schwarz, Corradi, Melnick catalogue.
Scott — J.L. Scott (double stars)
SCR — SuperCOSMOS-RECONS
SDSS — Sloan Digital Sky Survey
SDSSp — Sloan Digital Sky Survey, provisory
1SDSS — Sloan Digital Sky Survey, 1st release
2SDSS — reserved by the Sloan Digital Sky Survey for future release. The name is reserved to the IAU, but does not exist yet.
3SDSS — reserved by the Sloan Digital Sky Survey for future release. The name is reserved to the IAU, but does not exist yet.
Se — Father Angelo Secchi (double stars)
Se — Sersic (selected list of peculiar galaxies and groups of galaxies)
See — T.J.J. See (Thomas Jefferson Jackson See, 1866–1962) (double stars) (related to the 'Lambda' catalogue which is mentioned in T.W.Webb's Celestial Objects for Common Telescopes, Volume 2: The Stars, pages 285–319: Index of Double Stars, Epoch 2000).
SEGUE — Sloan Extension for Galactic Understanding and Exploration (for example: galaxies Segue 1 in Leo, Segue 2 in Aries, and Segue 3 in Pegasus)
Sei — J. Scheiner (double stars)
SGR — Soft Gamma Repeater
Sh — Sharpless catalog (Sh 1 (1953) & Sh 2 (1959))
Sh — Sher (open star clusters) (for example: Sher 1 at 11:01:04 / -60°14'00" in Carina)
S, h — James South / John Herschel (joint 1824 catalogue of double stars)
Shk — Romela Karapet Shakhbazian (compact groups of galaxies) (for example: Shakhbazian 1 (the 'Russian Cluster') at 10:54.8 / +40°28' in Ursa Major)
Shorlin — (for example: open star cluster Shorlin 1 at 11:05:46 / -61°13'48" in Carina)
Simeis — (for example: supernova remnant Simeis 147 / Sh2-240 in Taurus, also known as the 'Spaghetti Nebula')
SIMP — Sondage Infrarouge de Mouvement Propre
Sinnott — (multiple star systems)
SIPS — Southern Infrared Proper Motion Survey
Sk — Skinner (double stars)
SL — Sandqvist-Lindroos (dark nebulae)
Slr — R.P. Sellors (double stars)
Smart — W.M. Smart (double stars)
Smyth — W.H. Smyth (1788–1865) (double stars)
Sn — Shane (planetary nebulae)
Sp — Giovanni Schiaparelli (double stars)
Sp — Shapley (planetary nebulae)
Spano — (telescopic asterisms)
SPF2 — Second Cat of Fundamental Stars
SPF3 — Third Santiago-Pulkovo Fundamental Star Catalogue
SPOCS — Spectroscopic Properties of Cool Stars
SRS — Southern Reference Star Catalog
SS — Sadler and Sharp (survey of E-type and S0-type galaxies)
SS — Sanduleak-Stephenson (for example: SS 433 in Aquila)
SSSPM — SuperCOSMOS Sky Survey
SSTc2d — Spitzer Space Telescope c2d Legacy Source
SSTDUSTG — DUSTiNGS (Dust in Nearby Galaxies with Spitzer)
St — Carl L. Stearns (double stars)
Ste — Stephenson (open star clusters)
Stein — Johan Stein (double stars)
Steine — (open star clusters)
STF (Σ) — Friedrich Georg Wilhelm von Struve, aka 'Struve the Father' (double stars)
ΣI — W. Struve, First Supplement (double stars)
ΣII — W. Struve, Second Supplement (double stars)
St / Stock — Jürgen Stock (open star clusters) (Stock 1 and 2 in, Stock 3 to 23 in, Stock 24 in )
Stone — Ormond Stone (double stars)
Streicher — (telescopic asterisms)
Stromlo — (for example: Stromlo 2 in Monoceros and Canis Major, at IC 2177; the 'Eagle Nebula')
StWr — Stock-Wroblewski (planetary nebulae)
Sw — Swift (double stars)
SWEEPS — Sagittarius Window Eclipsing Extrasolar Planet Search
Swift (for example: Swift J1745-26 in Sagittarius) (stellar-mass black hole)
SwSt — Swings-Struve (planetary nebulae)
SyO — Sydney Observatory, Australia (double stars)
T
Ta — Tarrant (double stars)
TAC — Twin Astrograph Catalog
Tc — Thackeray (planetary nebulae)
TD1 — Catalogue of stellar UV fluxes (TD1 satellite)
Terzan — Agop Terzan Catalogue of Globular Star Clusters (11 objects)
THA — TH-alpha catalogue of emission line stars in the Eta Carinae nebula region
TIC — TESS Input Catalog
TIC — Tycho Input Catalog
TOI — TESS Object of Interest
Tom — Clyde Tombaugh (open star clusters)
Ton — Tonantzintla Catalogue (globular star clusters)
TPK — Teutsch-Patchick-Kronberger (asterisms) (for example: Teutsch-Patchick-Kronberger 1 at 23:39.3 / +47°30', north of the former constellation Honores Friderici in Andromeda)
TRAPPIST — Transiting Planets and Planetesimals Small Telescope
TrES — Trans-Atlantic Exoplanet Survey
TrES-And0 — TrES of planetary candidate in the Andromeda constellation
TVLM — Tinney's Very Low Mass Catalogue
TYC — Tycho Catalogue
TYC2 — Tycho-2 Catalogue
Tr / Trumpler — Robert Julius Trumpler's open cluster list, published in Preliminary results on the distances, dimensions and space distribution of open star clusters
Tu — Tucker (double stars)
Turner — David G. Turner (?) (open star clusters) (for example: Turner 9 at and near the variable star SU Cygni, aka 'SU Cygni cluster')
U
UBV — Photoelectric Catalogue, magnitude and color of stars in UBV (Blanco et al. 1968)
UBV M — UBV Photoelectric Photometry Catalogue (Mermilliod 1987)
UCAC — USNO CCD Astrograph Catalog (UCAC1, UCAC2, UCAC3 & UCAC4)
UGC — Uppsala General Catalogue (galaxies)
UGCA — Uppsala Selected non-UGC Galaxies
UKS — United Kingdom Schmidt (globular star clusters)
ULAS — UKIDDS Large Area Survey (quasars)
Up — Upgren (open star clusters) (only one object in this catalogue? Upgren 1) (probably Arthur R. Upgren, 1933–2017)
Up — Upton (double stars)
USNO — US Naval Observatory
USNO-A1.0— US Naval Observatory, A1.0 catalogue
USNO-A2.0 — US Naval Observatory, A2.0 catalogue
USNO-B1.0 — US Naval Observatory, B1.0 catalogue
uvby98 — uvbyβ photoelectric photometric catalogue, by B. Hauck, M. Mermilliod, Astron. Astrophys., Suppl. Ser., 129, 431–433 (1998)
V
vB — Van Biesbroeck's star catalog, variant, "VB"
VBRC (?)
VCC — Virgo Cluster Catalog
Vd — Vandervort (planetary nebulae)
VdB — Van den Bergh (catalogue of reflection nebulae)
VdB-H — Van den Bergh-Herbst (open star clusters)
VdB-Ha — Van den Bergh-Hagen (open star clusters)
VFTS — VLT Flames Tarantula Survey
Vou — J.G.E.G. Voute (double stars)
VPHAS+ The VST Photometric Hα Survey of the Southern Galactic Plane and Bulge
VV — Vorontsov-Vel'yaminov Interacting Galaxies (Boris Aleksandrovich Vorontsov-Vel'yaminov)¨
VVV Survey — Vista Variables in the Via Lactea (Latin for Milky Way)
VVV-CL — (open star clusters, I.R.)
Vy — Vyssotsky (planetary nebulae) (Alexander Vyssotsky)
W
W — Radiosource (Westerhout)
W20 — Washington 20 Catalog
Wa / Ward — I.W. Ward (double stars)
Wa — Waterloo (open star clusters)
WASP — Wide Angle Search for Planets
WASP0-TR — Wide Angle Search for Planets, Transit
WDS — Washington Double Star Catalog
We — Weinberger (planetary nebulae) (Ronald Weinberger)
We — Westerlund (open star clusters) (Bengt Westerlund, 1921–2008)
Webb — T.W. Webb (double stars)
WeDe — Weinberger-Dengle (planetary nebulae)
Weisse — M. Weisse (double stars)
WeSa — Weinberger-Sabbadin (planetary nebulae)
Wg — R.W. Wrigley (double stars)
Whiting — Alan B. Whiting (globular star clusters) (for example: Whiting 1 at 2h 02m / -3° 15' in Cetus)
WhMe — Whitelock-Menzies
Willman — Beth Willman (for example: ultra low-luminosity dwarf galaxy or star cluster Willman 1 in Ursa Major)
Wils — R.H. Wilson, Jr. (double stars)
Win — Winlock (double stars)
Wirtz — Carl Wirtz (double stars)
WISE — Wide-field Infrared Survey Explorer
WISEA — AllWISE Source Catalog
WISEP — Wide-field Infrared Survey Explorer Preliminary Release Source Catalog
WNC / Winn — Winnecke Catalogue of Double Stars
WNO — Washington Observations (double stars) (U.S. Naval Observatory, Washington D.C.)
Wo — Woolley Nearby Star Catalogue
Wolf — Catalogue of High Proper Motion Stars (Wolf)
Worley — Charles E. Worley (double stars)
WR — Catalog of Galactic Wolf-Rayet stars (Charles Wolf / Georges Rayet)
X
XBS — XMM-Newton, Bright Source
XBSS — XMM-Newton Bright Serendipitous Survey
XEST — XMM-Newton Extended Survey of the Taurus Molecular
XEST-OM — XEST, Optical/UV Monitor
XO — XO-Project (XO Telescope) (search for extrasolar planets)
XTE — X-ray Timing Explorer
XZ — XZ Catalogue of Zodiacal Stars (Richard Schmidt / Tom Van Flandern, 1977, U.S. Naval Observatory)
Y
Y — Young (double stars)
YBS — Yale Bright Star Catalogue
YZ — Yale Observatory Zone Catalog
Z
Z — Fritz Zwicky, Catalogue of galaxies and of clusters of galaxies
ZC — Robertson's Zodiacal Catalogue (James Robertson's catalogue of 3539 zodiacal stars brighter than 9th magnitude)
Zij — Islamic astronomical books that tabulates parameters used for astronomical calculations of the positions of the Sun, Moon, stars, and planets
Book of Fixed Stars
Tables of Toledo
Zij-i Ilkhani
Zij-i-Sultani
See also
Lists of astronomical objects
List of astronomical objects named after people
List of astronomy acronyms
List of common astronomy symbols
Glossary of astronomy
Modern constellations
References
External links
VizieR
CDS Service for Astronomical Catalogues
Dictionary of Nomenclature of Celestial Objects
Astronomical catalogues | List of astronomical catalogues | Astronomy | 12,956 |
1,885,452 | https://en.wikipedia.org/wiki/Service%20control%20point | A service control point (SCP) is a standard component of the Intelligent Network (IN) telephone system which is used to control the service. Standard SCPs in the telecom industry today are deployed using SS7, SIGTRAN or SIP technologies. The SCP queries the service data point (SDP) which holds the actual database and directory. SCP, using the database from the SDP, identifies the geographical number to which the call is to be routed. This is the same mechanism that is used to route 800 numbers.
SCP may also communicate with an intelligent peripheral (IP) to play voice messages, or prompt for information from the user, such as prepaid long distance using account codes. This is done by implementing telephone feature codes like "#", which can be used to terminate the input for a user name or password or can be used for call forwarding. These are realized using Intelligent Network Application Part (INAP) that sits above Transaction Capabilities Application Part (TCAP) on the SS7 protocol stack. The TCAP is part of the top or 7th layer of the OSI layer breakdown.
SCPs are connected with either SSPs or STPs. This is dependent upon the network architecture that the network service provider wants. The most common implementation uses STPs.
SCP and SDP split is becoming a common industry practice. This is known generally in the industry by split architecture. Reason is that operators want to decouple the dependency between the two functionality to facilitate upgrades and possibly rely on different vendors.
External links
See Telcordia GR-1299-CORE, for Service Control Point/Adjunct Interface generic requirements.
References
Network architecture
Telephony equipment
Signaling System 7 | Service control point | Engineering | 345 |
25,739,045 | https://en.wikipedia.org/wiki/Angstrom | The angstrom (; ) is a unit of length equal to m; that is, one ten-billionth of a metre, a hundred-millionth of a centimetre, 0.1 nanometre, or 100 picometres. The unit is named after the Swedish physicist Anders Jonas Ångström (1814–1874). It was originally spelled with Swedish letters, as Ångström and later as ångström (). The latter spelling is still listed in some dictionaries, but is now rare in English texts. Some popular US dictionaries list only the spelling angstrom.
The unit's symbol is Å, which is a letter of the Swedish alphabet, regardless of how the unit is spelled. However, "A" or "A.U." may be used in less formal contexts or typographically limited media.
The angstrom is often used in the natural sciences and technology to express sizes of atoms, molecules, microscopic biological structures, and lengths of chemical bonds, arrangement of atoms in crystals, wavelengths of electromagnetic radiation, and dimensions of integrated circuit parts. The atomic (covalent) radii of phosphorus, sulfur, and chlorine are about 1 angstrom, while that of hydrogen is about 0.5 angstroms. Visible light has wavelengths in the range of 4000–7000 Å.
In the late 19th century, spectroscopists adopted of a metre as a convenient unit to express the wavelengths of characteristic spectral lines (monochromatic components of the emission spectrum) of chemical elements. However, they soon realized that the definition of the metre at the time, based on a material artifact, was not accurate enough for their work. So, around 1907 they defined their own unit of length, which they called "Ångström", based on the wavelength of a specific spectral line. It was only in 1960, when the metre was redefined in the same way, that the angstrom became again equal to metre. Yet the angstrom was never part of the SI system of units, and has been increasingly replaced by the nanometre ( m) or picometre ( m).
History
In 1868, Swedish physicist Anders Jonas Ångström created a chart of the spectrum of sunlight, in which he expressed the wavelengths of electromagnetic radiation in the electromagnetic spectrum in multiples of one ten-millionth of a millimetre (or .) Ångström's chart and table of wavelengths in the solar spectrum became widely used in the solar physics community, which adopted the unit and named it after him. It subsequently spread to the fields of astronomical spectroscopy, atomic spectroscopy, and then to other sciences that deal with atomic-scale structures.
Early connection to the metre
Although intended to correspond to metres, that definition was not accurate enough for spectroscopy work. Until 1960 the metre was defined as the distance between two scratches on a bar of platinum-iridium alloy, kept at the BIPM in Paris in a carefully controlled environment. Reliance on that material standard had led to an early error of about one part in 6000 in the tabulated wavelengths. Ångström took the precaution of having the standard bar he used checked against a standard in Paris, but the metrologist Henri Tresca reported it to be so incorrect that Ångström's corrected results were more in error than the uncorrected ones.
Cadmium line definition
In 1892–1895, Albert A. Michelson and Jean-René Benoît, working at the BIPM with specially developed equipment, determined that the length of the international metre standard was equal to times the wavelength of the red line of the emission spectrum of electrically excited cadmium vapor. In 1907, the International Union for Cooperation in Solar Research (which later became the International Astronomical Union) defined the international angstrom as precisely 1/6438.4696 of the wavelength of that line (in dry air at 15 °C (hydrogen scale) and 760 mmHg under a gravity of 9.8067 m/s2).
This definition was endorsed at the 7th General Conference on Weights and Measures (CGPM) in 1927, but the material definition of the metre was retained until 1960. From 1927 to 1960, the angstrom remained a secondary unit of length for use in spectroscopy, defined separately from the metre.
Redefinition in terms of the metre
In 1960, the metre itself was redefined in spectroscopic terms, which allowed the angstrom to be redefined as being exactly 0.1 nanometres.
Angstrom star
After the redefinition of the metre in spectroscopic terms, the Angstrom was formally redefined to be 0.1 nanometres. However, there was briefly thought to be a need for a separate unit of comparable size defined directly in terms of spectroscopy. In 1965, J.A. Bearden defined the Angstrom Star (symbol: Å*) as 0.202901 times the wavelength of the tungsten line. This auxiliary unit was intended to be accurate to within 5 parts per million of the version derived from the new metre. Within ten years, the unit had been deemed both insufficiently accurate (with accuracies closer to 15 parts per million) and obsolete due to higher precision measuring equipment.
Current status
Although still widely used in physics and chemistry, the angstrom is not officially a part of the International System of Units (SI). Up to 2019, it was listed as a compatible unit by both the International Bureau of Weights and Measures (BIPM) and the US National Institute of Standards and Technology (NIST). However, it is not mentioned in the 9th edition of the official SI standard, the "BIPM Brochure" (2019) or in the NIST version of the same, and BIPM officially discourages its use. The angstrom is also not included in the European Union's catalogue of units of measure that may be used within its internal market.
Symbol
For compatibility reasons, Unicode assigns a code point for the angstrom symbol, which is accessible in HTML as the entity Å, Å, or Å. However, version 5 of the standard already deprecates that code point and has it normalized into the code for the Swedish letter (HTML entity Å, Å, or Å), which should be used instead.
In older publications, where the Å glyph was unavailable, the unit was sometimes written as "A.U.". An example is Bragg's 1921 classical paper on the structure of ice, which gives the c- and a-axis lattice constants as 4.52 A.U. and 7.34 A.U., respectively. Ambiguously, the abbreviation "a.u." may also refer to the atomic unit of length, the bohr—about 0.53 Å—or the much larger astronomical unit (about ).
See also
(for objects on this scale)
Conversion of units
X unit
References
External links
Non-SI metric units
Units of length | Angstrom | Mathematics | 1,438 |
7,515,615 | https://en.wikipedia.org/wiki/Day-year%20principle | The day-year principle or year-for-a-day principle is a method of interpretation of Bible prophecy in which the word day in prophecy is considered to be symbolic of a year of actual time. It was the method used by most of the Reformers, and is used principally by the historicist school of prophetic interpretation. It is actively taught by the Seventh-day Adventist Church, Jehovah's Witnesses, and the Christadelphians, though the understanding is not unique to these Christian denominations; since for example, it is implied in the Prophecy of Seventy Weeks. The day-year principle is also used by the Baháʼí Faith, as well with by most all astrologers who employ the "Secondary Progression" theory, aka the day-for-a-year theory, wherein the planets are moved forwards in the table of planetary motion (known as an ephemeris) a day for each year of life or fraction thereof. The astrologers say that the four seasons of the year are directly spiritually, phenomenologically like the four "seasons" of the day.
Biblical basis
Proponents of the principle, such as the Seventh-day Adventists, claim that it has three primary precedents in Scripture:
. The Israelites will wander for 40 years in the wilderness, one year for every day spent by the spies in Canaan.
. The prophet Ezekiel is commanded to lie on his left side for 390 days, followed by his right side for 40 days, to symbolize the equivalent number of years of punishment on Israel and Judah respectively.
. This is known as the Prophecy of Seventy Weeks. The majority of scholars do understand the passage to refer to 70 "sevens" or "septets" of years—that is, a total of 490 years.
While not listed as primary precedent by the proponents, some supporters cite a direct reference to the day-for-a-year concept is made in Genesis.
. Laban requires an additional seven years of work in contract for Rachel's hand in marriage, calling it a week.
Jon Paulien has defended the principle from a systematic theology perspective, not strictly from the Bible.
History
The day-year principle was partially employed by Jews as seen in Daniel 9:24–27, Ezekiel 4:4-7 and in the early church. It was first used in Christian exposition in 380 AD by Ticonius, who interpreted the three and a half days of Revelation 11:9 as three and a half years, writing 'three days and a half; that is, three years and six months' ('dies tres et dimidium; id est annos tres et menses sex'). In the 5th century Faustus of Riez gave the same interpretation of Revelation 11:9, writing 'three and a half days which correspond to three years and six months' ('Tres et dimidius dies tribus annis et sex mensibus respondent), and in c. 550 Primasius also gave the same interpretation, writing 'it is possible to understand the three days and a half as three years and six months' ('Tres dies et dimidium possumus intelligere tres annos et sex menses'). The same interpretation of Revelation 11:9 was given by later expositors like Anspert, Haymo, and Berengaudus (all of the ninth century). Primasius appears to have been the first to appeal directly to previous Biblical passages in order to substantiate the principle, referring to Numbers 14:34 in support of his interpretation of the three and a half days of Revelation 11:9. Haymo and Bruno Astensis "justify it by the parallel case of Ezekiel lying on his side 390 days, to signify 390 years; — i. e. a day for a year. — ". Protestant Reformers were well established on the day/year principle and it was also accepted by many Christian groups, ministers, and theologians.
Others who expounded the Historicist interpretation are John Wycliffe, John Knox, William Tyndale, Martin Luther, John Calvin, Ulrich Zwingli, Philip Melanchthon, Isaac Newton, Jan Hus, John Foxe, John Wesley, Jonathan Edwards, George Whitefield, Charles Finney, C. H. Spurgeon, Matthew Henry, Adam Clarke, Albert Barnes, and Bishop Thomas Newton.
Christian historicist application
70 weeks or 490-year prophecy
Daniel 9 contains the Prophecy of Seventy Weeks. Biblical scholars have interpreted the 70 weeks vision in the historistical methodology for nearly two millennia as illustrated in the following table.
The vision of the 70 weeks is interpreted as dealing with the Jewish nation from about the middle of the 5th century BCE until not long after the death of Jesus in the 1st century CE and so is not concerned with current or future history. Historicists consider Antiochus Epiphanies irrelevant to the fulfillment of the prophecy.
Historicist interpretation of the Prophecy of Seventy Weeks was that it foretells with great specificity information about Jesus as the Messiah, not some lowlevel official or antichrist figure. Daniel 9:25 states that the 'seventy weeks' (generally interpreted as 490 years according to the day-year principle) is to begin "from the time the word goes out to restore and rebuild Jerusalem," which is when the Persian king Artaxerxes I, gave the decree to rebuild Jerusalem to Ezra, so the 490 years point to the time of Christ's anointing.
In the 21st century this interpretation (emphasized by the 19th-century Millerite movement) is still held by Seventh-day Adventists and other groups.
Seventh-day Adventists
The Seventh-day Adventist interpretation of Daniel chapter 9 presents the 490 years as an uninterrupted period. Like others before them they equate the beginning of the 70 weeks "from the time the word goes out to rebuild and restore Jerusalem," of Daniel 9:25 with the decree by Artaxerxes I in 458/7 BC which provided money for rebuilding the temple and Jerusalem and allowed for restoration of a Jewish administration. It ends 3½ years after the crucifixion. The appearance of "Messiah the Prince" at the end of the 69 weeks (483 years) is aligned with Jesus' baptism in 27 CE, in the fifteenth year of Tiberius Caesar. The 'cutting off' of the "anointed one" refers to the crucifixion 3½ years after the end of the 483 years, bringing "atonement for iniquity" and "everlasting righteousness". Jesus is said to 'confirm' the "covenant" between God and mankind by his death on the cross in the Spring (about Easter time) of 31 CE "in the midst of" the last seven years. At the moment of his death the 4 inch (10 cm) thick curtain between the Holy and Most Holy Places in the Temple ripped from top to bottom, marking the end of the Temple's sacrificial system. The last week ends 3½ years after the crucifixion (i.e., in 34 AD) when the gospel was redirected from only the Jews to all peoples.
Some of the representative voices among exegetes of the last 150 years are E. W. Hengstenberg, J. N. Andrews, E. B. Pusey, J. Raska, J. Hontheim, Boutflower, Uriah Smith, and O. Gerhardt.
To understand 70-week prophecy of Daniel 9:24-27, one has to use the key. The Prophecy of Seventy Weeks becomes clear, as pointing to the messiah using the prophetic day-year principle. Using this, the 69 weeks, or the 483 years of Daniel 9, culminates in A.D. 27. Now "unto Messiah the Prince" makes sense and indicates the time for the coming of the "anointed one" or Messiah, with the final week during His ministry. It is not the time of the Messiah's birth but when He would appear as the Messiah, and this is right when Christ took up His ministry after being baptized. Thus the prophetic day-year principle correctly points to the anointed as the Messiah in A.D. 27 or the fifteenth year of Tiberius, not in the future or modern time. While there are other possible ways of reckoning, the beginning point of 457 B.C. as the starting point of the 70-week prophecy as the Messianic prophecies points to Jesus as the Messiah.
The seven and sixty-two-week periods are most frequently understood as consecutive, non-overlapping chronological periods that are more or less exact in terminating with the time at which Christ is anointed with the Holy Spirit at his baptism, with the terminus a quo of this 483-year period being the time associated with the decree given to Ezra by Artaxerxes I in 458/7 BCE. The reference to an anointed one being "cut off" in verse 26a is identified with the death of Christ and has traditionally been thought to mark the midpoint of the seventieth week, which is also when Jeremiah's new "covenant" is "confirmed" (verse 27a) and atonement for "iniquity" (verse 24) is made.
1260 year prophecy
Historicist interpreters have usually understood the "time, times and half a time" (i.e. 1+2+0.5=3.5), "1,260 days" and "42 months" mentioned in Daniel and Revelation to be references to represent a period of 1260 years (based on the 360 day Jewish year multiplied by 3.5).
These time periods occur seven times in scripture:
, "time, times and a half".
, "time, times and a half".
, "42 months".
, "1260 days".
, "1260 days".
, "time, times and a half".
, "42 months".
Historicists usually believe the "1,260 days" spanned the Middle Ages and concluded within the early modern or modern era. Although many dates have been proposed for the start and finish of the "1,260 days", certain time spans have proven to be more popular than others. The majority of historicists throughout history have identified the "1,260 days" as being fulfilled by one or more of the following time spans and identify the Papal Office as the Antichrist and culmination of the Great Apostasy:
538 AD to 1798: Siege of Rome to Napoleon's Roman Republic, when the Pope was taken prisoner.
606 AD to 1866
756 AD to 2016 Donation of Pepin to (presumed) fall of Papacy.
774 AD to 2034 Charlemagne overthrows last Lombard King.
800 AD to 2060 Charlemagne is crowned Holy Roman Emperor by the Pope.
Seventh-Day Adventist interpretation
The Millerites, like the earlier Bible students of the Reformation and post-Reformation eras and the Seventh-day Adventists, understand the 1260 days as lasting AD 538 to 1798 as the duration of the papacy over Rome. This period began with the defeat of the Ostrogoths by the general Belisarius and ended with the successes of French general Napoleon Bonaparte, specifically, the capture of Pope Pius VI by general Louis Alexandre Berthier in 1798. Seventh-day Adventist use of this principle in Daniel 8:14 is deemed to be of extra-biblical authority (i.e., William Miller/Ellen White-church prophetess) due to the Hebrew word "yowm" not extant in the text of Daniel 8:14. This is the word necessary to meet the Numbers 14:34 and Ezekiel 4:6 day/year principal texts.
Other views
Robert Fleming writing in 1701 (The Rise and Fall of Rome Papal) stated that the 1260-year period should commence with Pope Paul I becoming a temporal ruler in AD 758 which would expire in 2018 by counting Julian years, or the year 2000 if counting prophetic (360 day) years.
Charles Taze Russel, founder of the Watchtower Society (now known as Jehovah's Witnesses), originally taught that "1874 onward is the time of the Lord's second presence" using the day-year principle to understand the Bible. Later, under the leadership of Joseph Rutherford, Jehovah's Witnesses revised this teaching to state that they "pointed to 1914 as the time for this great event to occur." This is the doctrine still in use today.
756 to 2016
British Theologian Adam Clarke writing in 1825 stated that the 1260-year period should commence with 755 AD, the actual year Pepin the Short invaded Lombard territory, resulting in the Pope's elevation from a subject of the Byzantine Empire to an independent head of state. The Donation of Pepin, which first occurred in 754 and again in 756 gave to the Pope temporal power over the Papal States. However, his introductory comments on Daniel 7 added 756 as an alternative commencement date. In April of that year, Pepin, accompanied by Pope Stephen II entered northern Italy from France, forcing the Lombard King Aistulf to lift his siege of Rome, and return to Pavia. Following Aistulf's capitulation, Pepin remained in Italy until finalizing his Donations. Based on this, 19th century commentators anticipate the end of the Papacy in 2016:
Of the five areas of the Bible which mention this timeline, only Revelation 11:9-12 adds a brief 3½ more years to the end of this 1260-year period. If added to 2016, this would bring us to autumn of 2019 or spring of 2020 for the commencement of the Eternal Kingdom. However, far more attention is paid by historicists to 2016 as the final end of the Papacy and the commencement of the Millennial rule than there is to 2019. This may be due in part, to uncertainty as to who or what the two witnesses of the Book of Revelation represent. But for those 17th to 19th century historicists adhering to the day year principle who also predicted a literal restoration of the unconverted Jews in their original homeland, the fall of the Papacy immediately precedes the rapid conversion of the Jews. The two events are closely linked, with the former enabling the latter.
The year 756 AD is also thought to occur 666 years from John's writing of the Book of Revelation. The verse in Daniel 8:25 which reads "...but he shall be broken without hand" is usually understood to mean that the destruction of the "little horn" or Papacy will not be caused by any human action. Volcanic activity is described as the means by which Rome will be overthrown. The following excerpt is from the 5th edition (1808) of the Rev. David Simpson's book "A Plea for Religion and the Sacred Writings":
Though the end of the 1260 years will be marked by dramatic events, it will not instantly remove all the governments of the world. The Messianic Kingdom will be established in place of the former Roman Empire, and continue to expand until it has enveloped the remaining countries. The following is an excerpt from "The Covenanter", a Reformed Presbyterian publication (1857):
While Daniel 2:35 makes reference to the various world powers (represented as various metals) being "broken to pieces together", the previous verse (v.34) portrays the Eternal Kingdom coming as "a stone cut from a mountain without hands" and striking a statue (symbolizing the successive world empires) on its feet first. Most adherents of the day-year principle, interpret these feet "that were of iron and clay," as denoting the nations descended from and occupying areas of the former Roman Empire. The dominions of all the empires and nations are expected to be crushed simultaneously, but the end of "life" or existence of the Roman derived countries will precede that of the other nations of the world.
The length of time for this worldwide expansion to complete is indicated in Daniel 7:12, which adds "As concerning the rest of the beasts, they had their dominion taken away: yet their lives were prolonged for a season and time." Henry Folbigg (1869) elaborated on this verse:
Prior to Adam Clarke (Methodist), Jonathan Edwards, an Evangelical Reformed (Congregational) theologian commented on the views of his more well-known predecessors and contemporaries, and wrote that Sir Isaac Newton, Robert Fleming (Presbyterian), Moses Lowman (Presbyterian), Phillip Doddridge (Congregational), and Bishop Thomas Newton (Anglican), were in agreement that the 1,260 timeline should be calculated from the year 756 AD.
F.A. Cox (Congregationalist) confirmed that this was the view of Sir Isaac Newton and others, including himself:
Thomas Williams also acknowledged that this was the predominant view among the leading Protestant theologians of his time:
The timeline was also printed in other denominational publications including Lutheran, Reformed, Baptist, Unitarian (Socinian), and in countries with sizeable Protestant populations such as the United Kingdom, France, Germany, Netherlands and the United States.
Catholicon, a monthly Catholic publication, implied (1816) that this timeline was more accurate than the other predictions of the time:
In 1870 the newly formed Kingdom of Italy annexed the remaining Papal States, depriving the Pope of his temporal rule. Unaware that Papal rule would be restored, (albeit on a greatly diminished scale) in 1929 as head of the Vatican City state, the historicist view that the Papacy is the Antichrist rapidly declined in popularity as one of the defining characteristics of the Antichrist (i.e. that he would also be a political temporal power at the time of the return of Jesus) was no longer met.
In spite of its one time predominance, the 2016 prediction was largely forgotten and no major Protestant denomination currently subscribes to this timeline.
2300 year prophecy
The distinctly Seventh-day Adventist doctrine of the divine investigative judgment beginning in 1844, based on the 2300 day prophecy of , relies on the day-year principle. The 2300 days are understood to represent 2300 years stretching from 457 BC, the calculated starting date of the 70 weeks prophecy based on the 3rd decree found in Ezra, to 1844.
The prophecy of 2300 days in Verse 14 plays an important role in Seventh-day Adventist eschatology. The Seventh-day Adventist Church traces its origins to the William Miller, who predicted that the second coming of Jesus would occur in 1844 by assuming that the cleansing of the Sanctuary of Daniel 8:14 meant the destruction of the earth, and applying the day-year principle.
The prophetic time always uses the day-year principle, thus "2300 days" was understood to be 2300 years. Starting at the same time as the Prophecy of Seventy Weeks found in Chapter 9, on the grounds that the 70 weeks were "decreed" (actually "cut off") for the Jewish people from the 2300-day prophecy. This beginning year is calculated to be 457 BC (see details here), then the end of the 2300 years would have been in 1844.
Although the Millerites originally thought that 1844 represented the end of the world, those who later became Seventh-day Adventist reached the conclusion that 1844 marked the beginning of a divine pre-advent judgment called "the cleansing of the sanctuary". It is intimately related to the history of the Seventh-day Adventist Church and was described by the church's prophet and pioneer Ellen G. White as one of the pillars of Adventist belief.
Baháʼí Faith application
Baháʼí recognition of the 2300 day-year prophecy
Followers of the Baháʼí Faith also recognize the Day-Year Principle and use it in understanding prophecy from the Bible. In the book, Some Answered Questions, `Abdu'l-Bahá outlines a similar calculation for the 2300-year prophecy as given in the Christian section above. By applying the day-year principle, he demonstrates that the fulfillment of the vision of Daniel occurred in the year 1844, the year of the Báb's declaration in Persia i.e. the starting date of the Baháʼí Faith. This is the same year that the Millerites predicted for the return of Christ, and Baháʼís believe that William Miller's methodologies were indeed sound.
The prophecy states "For two thousand three hundred days; then the sanctuary shall be cleansed." (Daniel 8:14)
Baháʼís understand the "cleansing of the sanctuary" to be the restoration of religion to a state in which it is guided by authorities appointed by its Founder rather than by people who have appointed themselves as the authority. (The leaders of Sunni Islam were self-appointed; the first 12 leaders of Shia Islam had been appointed through a chain of succession going back to Muhammad, but that chain ended after 260 years—see next section below.)
Thus Baháʼís believe that divinely-guided religion was re-established in 1844 with the revelation of the Báb, continued through the revelation of the Baháʼí founder (Baha'u'llah) and continues today through their Universal House of Justice, elected according to the method described by Baha'u'llah.
Although Christians have generally expected their Messiah to appear somewhere in Judeo-Christian lands, Baháʼís have noted that Daniel himself was in Persia at the time the prophecy was made. He was in Shushan (modern day Susa or Shūsh, Iran), when he received his prophetic vision (Daniel 8:2). The Bab appeared 2300 years later in Shiraz, about 300 miles away from where Daniel's vision occurred.
Convergence of 1260-day prophecy and the 2300-day prophecy
The year 1260 was significant in Shia Islam, independently of any Biblical reference. The Shia branch of Islam followed a series of 12 Imams, whose authority they traced back to Muhammad. The last of these disappeared in the Islamic year 260 AH. According to a reference in the Qur'an, authority was to be re-established after 1,000 years. For this reason, there was widespread anticipation among Shi'ites that the 12th Imam would return in Islamic year 1260 AH. This is also the year 1844 AD in the Christian calendar. Thus both the Millerites and the Shi'ites were expecting their Promised One to appear in the same year, although for entirely independent reasons.
Therefore, Baháʼís understand the 1260-day prophecies in both Daniel and in the Book of Revelation as referring to the year 1260 of the Islamic calendar which corresponds to the year 1844 AD, the year the Báb pronounced himself to be a Messenger of God and the year that the Baháʼí Faith began.
Day-year principle in Revelation 9:15 (391 days)
Baháʼís have also applied the Day-Year principle to Rev. 9:15 which states, "And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men."
The slaying of "the third part of men" was interpreted by some Christian scholars to refer to the fall of the Eastern Orthodox part of Christianity, centered on Constantinople in the year 1453 AD. (The other two-thirds being the Western Christian world, centered on Rome, and the southern part of the Christian world in North Africa, which was already under the dominion of Islam long before 1453.) Using the day-year principle, the formula gives 1+30+360 days = 391 days = 391 years after 1453. Adding 391 years to 1453 brings the prediction again to 1844, the same year as the 2300 day prophecy of Daniel 8.
Theoretically, this prophecy could be taken one step further, since there are accurate records of the dates of the start and end of battle for Constantinople. If "the hour" is taken to be 1/24th of a day, then, by the day-year principle, it would equate to 1/24 of a year i.e. 15 days. Since the battle of Constantinople lasted for several weeks, it is not possible to pin down the exact starting day of this 391-1/24-year prophecy, but if the formula is followed to this degree, it suggests the prophecy's fulfillment should have occurred sometime in May or June 1844.
Day-year principle in Daniel 12: 1290- and 1335-day prophecies
In addition, Baháʼís have applied the Day-Year principle to the two prophecies at the end of the last chapter of Daniel concerning the 1290 days (Dan 12:11) and the 1335 days (Dan 12:12). The 1290 days is understood as a reference to the 1290 years from the open declaration of Muhammad to the open declaration of Baha'u'llah. The 1335 days is understood to be a reference to the firm establishment of Islam in 628 AD to the firm establishment of the Baháʼí Faith (the election of its Universal House of Justice) in 1963 AD.
See also
Abomination of desolation
Christian eschatology
Daniel 7
Daniel 8
Day-age creationism
Four Horsemen of the Apocalypse
Great Disappointment
Historicism
Judgment day
Premillennialism
Prewrath
Prophetic Year
Post-tribulation rapture
Rapture
Whore of Babylon
References
Further reading
Supportive:
William H. Shea, "Year-Day Principle – Part 1" (p67–104) and Part 2 (p105–110) in Selected Studies in Prophetic Interpretation; Daniel and Revelation Committee Series, vol 1. Maryland: Biblical Research Institute/Review and Herald, rev edn, 1982. Part 1 has been called "arguably the [Adventist] church's best scholarly defense of the day-year principle."
Gerhard F. Hasel, "The Hebrew Masculine Plural for 'Weeks' in the Expression 'Seventy Weeks' in Daniel 9:24" (AUSS 31/2 [1993] 105–18).
Frank W. Hardy, "The Hebrew Singular for 'Week' in the Expression 'One Week' in Daniel 9:27" (AUSS 32/3 [1994] 197–202).
Desmond Ford, Daniel appendix (note the author has since changed his position – see below)
Undetermined:
Kai Arasola, The End of Historicism (PhD thesis). This is a history, which includes the decline of use of the day-year principle
Christian eschatology
Seventh-day Adventist theology
Numerology
Prophecy in Christianity
Hermeneutics | Day-year principle | Mathematics | 5,468 |
188,972 | https://en.wikipedia.org/wiki/Silane | Silane (Silicane) is an inorganic compound with chemical formula . It is a colorless, pyrophoric gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Silanes with alkyl groups are effective water repellents for mineral surfaces such as concrete and masonry. Silanes with both organic and inorganic attachments are used as coupling agents. They are commonly used to apply coatings to surfaces or as an adhesion promoter.
Production
Commercial-scale routes
Silane can be produced by several routes. Typically, it arises from the reaction of hydrogen chloride with magnesium silicide:
It is also prepared from metallurgical-grade silicon in a two-step process. First, silicon is treated with hydrogen chloride at about 300 °C to produce trichlorosilane, HSiCl3, along with hydrogen gas, according to the chemical equation
The trichlorosilane is then converted to a mixture of silane and silicon tetrachloride:
This redistribution reaction requires a catalyst.
The most commonly used catalysts for this process are metal halides, particularly aluminium chloride. This is referred to as a redistribution reaction, which is a double displacement involving the same central element. It may also be thought of as a disproportionation reaction, even though there is no change in the oxidation number for silicon (Si has a nominal oxidation number IV in all three species). However, the utility of the oxidation number concept for a covalent molecule, even a polar covalent molecule, is ambiguous. The silicon atom could be rationalized as having the highest formal oxidation state and partial positive charge in and the lowest formal oxidation state in , since Cl is far more electronegative than is H.
An alternative industrial process for the preparation of very high-purity silane, suitable for use in the production of semiconductor-grade silicon, starts with metallurgical-grade silicon, hydrogen, and silicon tetrachloride and involves a complex series of redistribution reactions (producing byproducts that are recycled in the process) and distillations. The reactions are summarized below:
The silane produced by this route can be thermally decomposed to produce high-purity silicon and hydrogen in a single pass.
Still other industrial routes to silane involve reduction of silicon tetrafluoride () with sodium hydride (NaH) or reduction of with lithium aluminium hydride ().
Another commercial production of silane involves reduction of silicon dioxide () under Al and gas in a mixture of NaCl and aluminum chloride () at high pressures:
Laboratory-scale routes
In 1857, the German chemists Heinrich Buff and Friedrich Woehler discovered silane among the products formed by the action of hydrochloric acid on aluminum silicide, which they had previously prepared. They called the compound siliciuretted hydrogen.
For classroom demonstrations, silane can be produced by heating sand with magnesium powder to produce magnesium silicide (), then pouring the mixture into hydrochloric acid. The magnesium silicide reacts with the acid to produce silane gas, which burns on contact with air and produces tiny explosions. This may be classified as a heterogeneous acid–base chemical reaction, since the isolated ion in the antifluorite structure can serve as a Brønsted–Lowry base capable of accepting four protons. It can be written as
In general, the alkaline-earth metals form silicides with the following stoichiometries: , , and . In all cases, these substances react with Brønsted–Lowry acids to produce some type of hydride of silicon that is dependent on the Si anion connectivity in the silicide. The possible products include and/or higher molecules in the homologous series , a polymeric silicon hydride, or a silicic acid. Hence, with their zigzag chains of anions (containing two lone pairs of electrons on each Si anion that can accept protons) yield the polymeric hydride .
Yet another small-scale route for the production of silane is from the action of sodium amalgam on dichlorosilane, , to yield monosilane along with some yellow polymerized silicon hydride .
Properties
Silane is the silicon analogue of methane. All four bonds are equal and their length is 147.98 pm. Because of the greater electronegativity of hydrogen in comparison to silicon, this Si–H bond polarity is the opposite of that in the C–H bonds of methane. One consequence of this reversed polarity is the greater tendency of silane to form complexes with transition metals. A second consequence is that silane is pyrophoric — it undergoes spontaneous combustion in air, without the need for external ignition. However, the difficulties in explaining the available (often contradictory) combustion data are ascribed to the fact that silane itself is stable and that the natural formation of larger silanes during production, as well as the sensitivity of combustion to impurities such as moisture and to the catalytic effects of container surfaces causes its pyrophoricity. Above , silane decomposes into silicon and hydrogen; it can therefore be used in the chemical vapor deposition of silicon.
The Si–H bond strength is around 384 kJ/mol, which is about 20% weaker than the H–H bond in . Consequently, compounds containing Si–H bonds are much more reactive than is . The strength of the Si–H bond is modestly affected by other substituents: the Si–H bond strengths are: 419 kJ/mol, 382 kJ/mol, and SiHMe3 398 kJ/mol.
Applications
While diverse applications exist for organosilanes, silane itself has one dominant application, as a precursor to elemental silicon, particularly in the semiconductor industry. The higher silanes, such as di- and trisilane, are only of academic interest. About 300 metric tons per year of silane were consumed in the late 1990s. Low-cost solar photovoltaic module manufacturing has led to substantial consumption of silane for depositing hydrogenated amorphous silicon (a-Si:H) on glass and other substrates like metal and plastic. The plasma-enhanced chemical vapor deposition (PECVD) process is relatively inefficient at materials utilization with approximately 85% of the silane being wasted. To reduce that waste and the ecological footprint of a-Si:H-based solar cells further several recycling efforts have been developed.
Safety and precautions
A number of fatal industrial accidents produced by combustion and detonation of leaked silane in air have been reported.
Due to weak bonds and hydrogen, silane is a pyrophoric gas (capable of autoignition at temperatures below ).
For lean mixtures a two-stage reaction process has been proposed, which consists of a silane consumption process and a hydrogen oxidation process. The heat of condensation increases the burning velocity due to thermal feedback.
Diluted silane mixtures with inert gases such as nitrogen or argon are even more likely to ignite when leaked into open air, compared to pure silane: even a 1% mixture of silane in pure nitrogen easily ignites when exposed to air.
In Japan, in order to reduce the danger of silane for amorphous silicon solar cell manufacturing, several companies began to dilute silane with hydrogen gas. This resulted in a symbiotic benefit of making more stable solar photovoltaic cells as it reduced the Staebler–Wronski effect.
Unlike methane, silane is slightly toxic: the lethal concentration in air for rats (LC50) is 0.96% (9,600 ppm) over a 4-hour exposure. In addition, contact with eyes may form silicic acid with resultant irritation.
In regards to occupational exposure of silane to workers, the US National Institute for Occupational Safety and Health has set a recommended exposure limit of 5 ppm (7 mg/m3) over an eight-hour time-weighted average.
See also
Binary silicon-hydrogen compounds (sometimes called silanes)
Silanization
Magnesium silicide
Methane, in which carbon (in that compound) and silicon (in this compound) are together in the carbon group.
References
Cited sources
External links
US Patent 2474087A, Preparation of silicon halides
Gases
Industrial gases
Silanes
Foul-smelling chemicals
Pyrophoric materials | Silane | Physics,Chemistry,Technology | 1,773 |
1,828,131 | https://en.wikipedia.org/wiki/Davisson%E2%80%93Germer%20experiment | The Davisson–Germer experiment was a 1923–1927 experiment by Clinton Davisson and Lester Germer at Western Electric (later Bell Labs), in which electrons, scattered by the surface of a crystal of nickel metal, displayed a diffraction pattern. This confirmed the hypothesis, advanced by Louis de Broglie in 1924, of wave-particle duality, and also the wave mechanics approach of the Schrödinger equation. It was an experimental milestone in the creation of quantum mechanics.
History and overview
According to Maxwell's equations in the late 19th century, light was thought to consist of waves of electromagnetic fields and matter was thought to consist of localized particles. However, this was challenged in Albert Einstein's 1905 paper on the photoelectric effect, which described light as discrete and localized quanta of energy (now called photons), which won him the Nobel Prize in Physics in 1921. In 1924 Louis de Broglie presented his thesis concerning the wave–particle duality theory, which proposed the idea that all matter displays the wave–particle duality of photons. According to de Broglie, for all matter and for radiation alike, the energy of the particle was related to the frequency of its associated wave by the Planck relation:
And that the momentum of the particle was related to its wavelength by what is now known as the de Broglie relation:
where is the Planck constant.
An important contribution to the Davisson–Germer experiment was made by Walter M. Elsasser in Göttingen in the 1920s, who remarked that the wave-like nature of matter might be investigated by electron scattering experiments on crystalline solids, just as the wave-like nature of X-rays had been confirmed through Barkla's X-ray scattering experiments on crystalline solids.
This suggestion of Elsasser was then communicated by his senior colleague (and later Nobel Prize recipient) Max Born to physicists in England. When the Davisson and Germer experiment was performed, the results of the experiment were explained by Elsasser's proposition. However the initial intention of the Davisson and Germer experiment was not to confirm the de Broglie hypothesis, but rather to study the surface of nickel.
In 1927 at Bell Labs, Clinton Davisson and Lester Germer fired slow moving electrons at a crystalline nickel target. The angular dependence of the reflected electron intensity was measured and was determined to have a similar diffraction pattern as those predicted by Bragg for X-rays; some small, but significant differences were due to the average potential which Hans Bethe showed in his more complete analysis. At the same time George Paget Thomson and his student Alexander Reid independently demonstrated the same effect firing electrons through celluloid films to produce a diffraction pattern, and Davisson and Thomson shared the Nobel Prize in Physics in 1937. The exclusion of Germer from sharing the prize has puzzled physicists ever since. The Davisson–Germer experiment confirmed the de Broglie hypothesis that matter has wave-like behavior. This, in combination with the Compton effect discovered by Arthur Compton (who won the Nobel Prize for Physics in 1927), established the wave–particle duality hypothesis which was a fundamental step in quantum theory.
Early experiments
Davisson began work in 1921 to study electron bombardment and secondary electron emissions. A series of experiments continued through 1925.
Prior to 1923, Davisson had been working with Charles H. Kunsman on detecting the effects of electron bombardment on tungsten when they noticed that 1% of the electrons bounced straight back to the electron gun in elastic scattering. This small but unexpected result led Davisson to theorize that he could examine the electron configuration of the atom in an analogous manner to how the Rutherford alpha particle scattering had examined the nucleus. They changed to a high vacuum and used nickel along with various other metals with unimpressive results.
In October 1924 when Germer joined the experiment, Davisson’s actual objective was to study the surface of a piece of nickel by directing a beam of electrons at the surface and observing how many electrons bounced off at various angles. They expected that because of the small size of electrons, even the smoothest crystal surface would be too rough and thus the electron beam would experience diffused reflection.
The experiment consisted of firing an electron beam (from an electron gun, an electrostatic particle accelerator) at a nickel crystal, perpendicular to the surface of the crystal, and measuring how the number of reflected electrons varied as the angle between the detector and the nickel surface varied. The electron gun was a heated tungsten filament that released thermally excited electrons which were then accelerated through an electric potential difference, giving them a certain amount of kinetic energy, towards the nickel crystal. To avoid collisions of the electrons with other atoms on their way towards the surface, the experiment was conducted in a vacuum chamber. To measure the number of electrons that were scattered at different angles, a faraday cup electron detector that could be moved on an arc path about the crystal was used. The detector was designed to accept only elastically scattered electrons.
During the experiment, air accidentally entered the chamber, producing an oxide film on the nickel surface. To remove the oxide, Davisson and Germer heated the specimen in a high temperature oven, not knowing that this caused the formerly polycrystalline structure of the nickel to form large single crystal areas with crystal planes continuous over the width of the electron beam.
When they started the experiment again and the electrons hit the surface, they were scattered by nickel atoms in crystal planes (so the atoms were regularly spaced) of the crystal. This, in 1925, generated a diffraction pattern with unexpected and uncorrelated peaks due to the heating causing a ten crystal faceted area. They changed the experiment to a single crystal and started again.
Breakthrough
On his second honeymoon, Davisson attended the Oxford meeting of the British Association for the Advancement of Science in summer 1926. At this meeting, he learned of the recent advances in quantum mechanics. To Davisson's surprise, Max Born gave a lecture that used the uncorrelated diffraction curves from Davisson's 1923 research on platinum with Kunsman, using the data as confirmation of the de Broglie hypothesis of which Davisson was unaware.
Davisson then learned that in prior years, other scientists – Walter Elsasser, E. G. Dymond, and Blackett, James Chadwick, and Charles Ellis – had attempted similar diffraction experiments, but were unable to generate low enough vacuums or detect the low-intensity beams needed.
Returning to the United States, Davisson made modifications to the tube design and detector mounting, adding azimuth in addition to colatitude. Following experiments generated a strong signal peak at 65 V and an angle . He published a note to Nature titled, "The Scattering of Electrons by a Single Crystal of Nickel".
Questions still needed to be answered and experimentation continued through 1927, because Davisson was now familiar with the de Broglie formula and had designed the test to see if any effect could be discerned for a changed electron wavelength , according to the de Broglie relationship, which they knew should create a peak at 78 and not 65 V as their paper had shown. Because of their failure to correlate with the de Broglie formula, their paper introduced an ad hoc contraction factor of 0.7, which, however, could only explain eight of the thirteen beams.
By varying the applied voltage to the electron gun, the maximum intensity of electrons diffracted by the atomic surface was found at different angles. The highest intensity was observed at an angle with a voltage of 54 V, giving the electrons a kinetic energy of .
As Max von Laue proved in 1912, the periodic crystal structure serves as a type of three-dimensional diffraction grating. The angles of maximum reflection are given by Bragg's condition for constructive interference from an array, Bragg's law
for , , and for the spacing of the crystalline planes of nickel () obtained from previous X-ray scattering experiments on crystalline nickel.
According to the de Broglie relation, electrons with kinetic energy of have a wavelength of . The experimental outcome was via Bragg's law, which closely matched the predictions. As Davisson and Germer state in their 1928 follow-up paper to their Nobel prize winning paper, "These results, including the failure of the data to satisfy the Bragg formula, are in accord with those previously obtained in our experiments on electron diffraction. The reflection data fail to satisfy the Bragg relation for the same reason that the electron diffraction beams fail to coincide with their Laue beam analogues." However, they add, "The calculated wave-lengths are in excellent agreement with the theoretical values of h/mv as shown in the accompanying table." So although electron energy diffraction does not follow the Bragg law, it did confirm de Broglie's theory that particles behave like waves. The full explanation was provided by Hans Bethe who solved Schrödinger equation for the case of electron diffraction.
Davisson and Germer's accidental discovery of the diffraction of electrons was the first direct evidence confirming de Broglie's hypothesis that particles can have wave properties as well.
Davisson's attention to detail, his resources for conducting basic research, the expertise of colleagues, and luck all contributed to the experimental success.
Practical applications
The specific approach used by Davisson and Germer used low energy electrons, what is now called low-energy electron diffraction (LEED). It wasn't until much later that development of experimental methods exploiting ultra-high vacuum technologies (e.g. the approach described by Alpert in 1953) enabled the extensive use of LEED diffraction to explore the surfaces of crystallized elements and the spacing between atoms. Methods where higher energy electrons are used for diffraction in many different ways developed much earlier.
References
External links
Foundational quantum physics
Physics experiments
1927 in science | Davisson–Germer experiment | Physics | 2,043 |
23,998,046 | https://en.wikipedia.org/wiki/Marshall%20Rose | Marshall T. Rose (born 1961) is an American network protocol and software engineer, author, and speaker who has contributed to the Internet Engineering Task Force (IETF), the Internet, and Internet and network applications. More specifically, he has specialized in network management, distributed systems management, applications management, email, the ISO Development Environment (ISODE), and service-oriented architecture (SOA).
Rose holds a Ph.D. in Information and Computer Science from the University of California, Irvine and is former area director for network management of the IETF.
Rose is presently Principal Engineer at Brave (web browser).
IETF
Rose's work on behalf of the Internet Engineering Task Force has included:
Area Director for network management, 1993-1995.
Chair, MARID, MTA Authorization Records in DNS. IETF working group, Applications area. Concluded September 2004.
Chair, OPES, Open Pluggable Edge Services. IETF working group, Applications area.
Chair, POP, Post Office Protocol. IETF working group, Applications area. Concluded April 1993.
Chair, SNMP, Simple Network Management Protocol. IETF working group, Network Management area. Concluded November 1991.
Books
Rose has written the following published books:
External links
Marshall Rose on Twitter
Marshall Rose's GitHub Profile
Marshall Rose's profile at IETF
References
1961 births
Living people
University of California, Irvine alumni
People in information technology
American software engineers
21st-century American writers
Engineers from California | Marshall Rose | Technology | 301 |
1,295,520 | https://en.wikipedia.org/wiki/Eugene%20Podkletnov | Eugene Podkletnov (, Yevgeny Podkletnov) is a Russian ceramics engineer known for his claims made in the 1990s of designing and demonstrating gravity shielding devices consisting of rotating discs constructed from ceramic superconducting materials.
Background and education
Podkletnov graduated from the University of Chemical Technology, Mendeleyev Institute, in Moscow; he then spent 15 years at the Institute for High Temperatures in the Russian Academy of Sciences. He received a doctorate in materials science from Tampere University of Technology in Finland. After graduation he continued superconductor research at the university, in the Materials Science department, until his expulsion in 1997. After which he moved back to Moscow where it is reported that he took an engineering job. Since leaving Tampere in 1997 Podkletnov has avoided public contact or appearances. There is a report that he later returned to Tampere to work on superconductors at Tamglass Engineering Oy.
Gravity shielding
According to the account Podkletnov gave to Wired reporter Charles Platt in a 1996 phone interview, during a 1992 experiment with a rotating superconducting disc:
"Someone in the laboratory was smoking a pipe, and the pipe smoke rose in a column above the superconducting disc. So we placed a ball-shaped magnet above the disc, attached to a balance. The balance behaved strangely. We substituted a nonmagnetic material, silicon, and still the balance was very strange. We found that any object above the disc lost some of its weight, and we found that if we rotated the disc, the effect was increased."
Public controversy
Podkletnov's first peer-reviewed paper on the apparent gravity-modification effect, published in 1992, attracted little notice. In 1996, he submitted a longer paper, in which he claimed to have observed a larger effect (2% weight reduction as opposed to 0.3% in the 1992 paper) to the Journal of Physics D. According to Platt, a member of the editorial staff, Ian Sample, leaked the submitted paper to Robert Matthews, the science correspondent for the British newspaper, the Sunday Telegraph.
On September 1, 1996, Matthews's story broke, leading with the startling statement: "Scientists in Finland are about to reveal details of the world's first anti-gravity device." In the ensuing uproar, the director of the laboratory where Podkletnov was working issued a defensive statement that Podkletnov was working entirely on his own. Vuorinen, listed as the paper's coauthor, disavowed prior knowledge of the paper and claimed that the name was used without consent. Podkletnov himself complained that he had never claimed to block gravity, only to have reduced its effect.
Podkletnov withdrew his second paper after it had been initially accepted. The resulting uproar over the alleged claims in the withdrawn paper is reported to be the primary reason for his expulsion from his lab and the termination of his employment at the university.
Attempted verification
In a 1997 telephone interview with Charles Platt, Podkletnov insisted that his gravity-shielding work was reproduced by researchers at universities in Toronto and Sheffield, but none have come forward to acknowledge this. The Sheffield work is known to have only been intended as partial replication, aimed at observing any unusual effects which might be present, since the team involved lacked the necessary facilities to construct a large enough disc and the ability to duplicate the means by which the original disc was rotated. Podkletnov counters that the researchers in question have kept quiet "lest they be criticized by the mainstream scientific community". Podkletnov is reported to have visited the Sheffield team in 2000 and advised them on the conditions necessary to achieve his effect, conditions that they never achieved.
In a BBC news item, it was alleged that researchers at Boeing were funding a project called GRASP (Gravity Research for Advanced Space Propulsion) which would attempt to construct a gravity shielding device based on rotating superconductors, but a subsequent Popular Mechanics news item stated that Boeing had denied funding GRASP with company money, although Boeing acknowledged that it could not comment on "black projects". It is alleged that the GRASP proposal was presented to Boeing and Boeing chose not to fund it.
In July 2002, an article by Nick Cook in Jane's Defence Weekly reported about Boeing's internal project GRASP — Gravity Research for Advanced Space Propulsion to evaluate the validity of Podkletnov's claims. The briefing obtained by Jane's says "If gravity modification is real, it will alter the entire aerospace business." The briefing allegedly says that Boeing, as well as BAE Systems and Lockheed Martin tried to approach Podkletnov directly and that "Podkletnov is strongly anti-military and will only provide assistance if the research is carried out in the 'white world' of open development."
See also
Anti-gravity
Ning Li
References
External links
Sven Piper on Antigravity Article about the current status of antigravity research from 2024
Eugene Podkletnov on Antigravity A recounting of recent work claimed by supporters in 2014.
Russia's 'gravity-beating' scientist A BBC News profile on Podkletnov from 2002.
Russian physicists
Russian inventors
Anti-gravity
Living people
Place of birth missing (living people)
Russian materials scientists
Superconductivity
D. Mendeleev University of Chemical Technology of Russia alumni
Year of birth missing (living people) | Eugene Podkletnov | Physics,Materials_science,Astronomy,Engineering | 1,107 |
3,831,024 | https://en.wikipedia.org/wiki/Electrodeless%20plasma%20thruster | The electrodeless plasma thruster is a spacecraft propulsion engine commercialized under the acronym "E-IMPAcT" for "Electrodeless-Ionization Magnetized Ponderomotive Acceleration Thruster". It was created by Gregory Emsellem, based on technology developed by French Atomic Energy Commission scientist Dr Richard Geller and Dr. Terenzio Consoli, for high speed plasma beam production.
The electrodeless plasma thruster was developed and adapted to various spacecraft propulsion needs by The Elwing Company between 2002 and 2015.
Operating principle
Propellant is injected at the upstream side of the thruster body. In cases where the propellant used is not gaseous (e.g., alkali metals) at the local temperature, the propellant must be vaporized.
Gaseous propellant is ionized by one of the following methods:
bombarding the propellant with electrons emitted by a hot cathode or by an electron gun.
a steady state electrical discharge between two electrodes.
applying an alternating electric field either via a capacitive discharge or an inductive discharge or even a helicon discharge.
electromagnetic waves of various frequency from radio frequency up to gamma rays, which is especially useful for solid propellant in which case the propellant can be simultaneously vaporized and ionized by a laser impulse.
As the ionization stage is subjected to a steady magnetic field, the ionization process can use one of the numerous resonances existing in magnetized plasma, such as ion cyclotron resonance (ICR), electron cyclotron resonance (ECR) or lower hybrid oscillation, to produce a high density cold plasma.
The cold and dense plasma, produced by the ionization stage, then drifts toward the acceleration stage by diffusion across a region of higher magnetic field intensity.
In the acceleration stage the propellant plasma is accelerated by magnetized ponderomotive force in an area where both non-uniform static magnetic fields and non-uniform high-frequency electromagnetic fields are applied simultaneously.
Advantages
This thruster technology can deliver large thrust density as the acceleration process is not limited by plasma density through Hall Parameter or grid electrical screening. Further, as the ponderomotive force accelerates all plasma species in the same direction, this thruster technology does not need any neutralizer. The fact that electrodeless plasma thruster is inherently multi-staged allows it to optimize both stages independently, or to throttle the thruster at constant power between higher specific impulse and higher thrust. The field of ponderomotive force is created by a non-uniform high frequency field and static magnetic field, thus it implies no grids nor contact between the plasma and any electrodes, hence it avoids most thruster erosion and spacecraft contamination issues.
Applications
Propulsion systems based on electrodeless plasma thrusters seem ideally suited for orbit raising for large geostationary satellites, and would also be able to perform orbital stationkeeping, hence enabling important propellant mass savings. The ability of this technology to provide large thrust density also allows faster missions to the outer planets.
Other research on the same phenomenon
The use of ponderomotive force to accelerate a plasma has recently been investigated from a theoretical point of view by Princeton Plasma Physics Laboratory scientists I. Y. Dodin, Y. Raitses and N. J. Fisch.
Some theoretical research has also been reported around the debated issue of the existence of a double layer in such a thruster, even if such a double layer structure would be current-free, as both ions and electrons travel in the same direction at the same average terminal speed. The existence of current free double layer is still debated among plasma physicists.
See also
Electrodeless plasma excitation
Electrodeless lamp
References
External links
AIAA paper on this technology
List of articles, presentations and patents by the Elwing Company on this technology
Ion engines
Spacecraft components | Electrodeless plasma thruster | Physics,Chemistry | 775 |
33,784,766 | https://en.wikipedia.org/wiki/SrnB-SrnC%20toxin-antitoxin%20system | The SrnB-SrnC toxin-antitoxin system of the F plasmid is homologous to the hok/sok system of R1. Like the hok/sok system, it performs a post-segregational killing function, ensuring that all surviving daughter cells inherit the F plasmid. The system consists of srnB' mRNA, which is relatively stable and codes for the toxic protein SrnB, srnB mRNA, a regulatory element and srnC mRNA, an antitoxin with complementarity to srnB.
Mechanism of regulation and toxicity
The suspected method of regulation has not been directly tested for this system, however due to the strong similarity between this system and the hok/sok system, a mechanism of regulation has been inferred based on the structure of the mRNA and the mechanism used to regulate hok expression. The gene system consists of a stretch coding for srnB' , srnB and srnC mRNA. srnB completely overlaps srnB' and is partly overlapped by srnC. It appears that translation of srnB' is dependent on translation of srnB, so regulation of expression of the SrnB toxin can be achieved indirectly by regulating translation of srnB. It is thought that the initial mRNA transcript of srnB' is translationally inactive, and in plasmid-containing cells it will slowly bind srnC mRNA and be cleaved, or it will be specifically cleaved on the 3' end and rapidly bind srnC, which indirectly inhibits translation of srnB' by regulating translation of srnB and causing cleavage. In a plasmid free cell, srnC degrades rapidly and remaining srnB' mRNA is processed into translationally active 3'-truncated mRNA which yields the SrnB toxic protein, killing the cell. The mechanism by which SrnB causes toxicity is not known, however similarity between the SrnB toxin sequence and the hok toxin sequence suggests that they make have similar functions.
References
RNA antitoxins | SrnB-SrnC toxin-antitoxin system | Biology | 413 |
254,452 | https://en.wikipedia.org/wiki/Planetary%20differentiation | In planetary science, planetary differentiation is the process by which the chemical elements of a planetary body accumulate in different areas of that body, due to their physical or chemical behavior (e.g. density and chemical affinities). The process of planetary differentiation is mediated by partial melting with heat from radioactive isotope decay and planetary accretion. Planetary differentiation has occurred on planets, dwarf planets, the asteroid 4 Vesta, and natural satellites (such as the Moon).
Physical differentiation
Gravitational separation
High-density materials tend to sink through lighter materials. This tendency is affected by the relative structural strengths, but such strength is reduced at temperatures where both materials are plastic or molten. Iron, the most common element that is likely to form a very dense molten metal phase, tends to congregate towards planetary interiors. With it, many siderophile elements (i.e. materials that readily alloy with iron) also travel downward. However, not all heavy elements make this transition as some chalcophilic heavy elements bind into low-density silicate and oxide compounds, which differentiate in the opposite direction.
The main compositionally differentiated zones in the solid Earth are the very dense iron-rich metallic core, the less dense magnesium-silicate-rich mantle and the relatively thin, light crust composed mainly of silicates of aluminium, sodium, calcium and potassium. Even lighter still are the watery liquid hydrosphere and the gaseous, nitrogen-rich atmosphere.
Lighter materials tend to rise through material with a higher density. A light mineral such as plagioclase would rise. They may take on dome-shaped forms called diapirs when doing so. On Earth, salt domes are salt diapirs in the crust which rise through surrounding rock. Diapirs of molten low-density silicate rocks such as granite are abundant in the Earth's upper crust. The hydrated, low-density serpentinite formed by alteration of mantle material at subduction zones can also rise to the surface as diapirs. Other materials do likewise: a low-temperature, near-surface example is provided by mud volcanoes.
Chemical differentiation
Although bulk materials differentiate outward or inward according to their density, the elements that are chemically bound in them fractionate according to their chemical affinities, "carried along" by more abundant materials with which they are associated. For instance, although the rare element uranium is very dense as a pure element, it is chemically more compatible as a trace element in the Earth's light, silicate-rich crust than in the dense metallic core.
Heating
When the Sun ignited in the solar nebula, hydrogen, helium and other volatile materials were evaporated in the region around it. The solar wind and radiation pressure forced these low-density materials away from the Sun. Rocks, and the elements comprising them, were stripped of their early atmospheres, but themselves remained, to accumulate into protoplanets.
Protoplanets had higher concentrations of radioactive elements early in their history, the quantity of which has reduced over time due to radioactive decay. For example, the hafnium-tungsten system demonstrates the decay of two unstable isotopes and possibly forms a timeline for accretion. Heating due to radioactivity, impacts, and gravitational pressure melted parts of protoplanets as they grew toward being planets. In melted zones, it was possible for denser materials to sink towards the center, while lighter materials rose to the surface. The compositions of some meteorites (achondrites) show that differentiation also took place in some asteroids (e.g. Vesta), that are parental bodies for meteoroids. The short-lived radioactive isotope 26Al was probably the main source of heat.
When protoplanets accrete more material, the energy of impact causes local heating. In addition to this temporary heating, the gravitational force in a sufficiently large body creates pressures and temperatures which are sufficient to melt some of the materials. This allows chemical reactions and density differences to mix and separate materials, and soft materials to spread out over the surface. Another external heat source is tidal heating.
On Earth, a large piece of molten iron is sufficiently denser than continental crust material to force its way down through the crust to the mantle.
In the outer Solar System, a similar process may take place but with lighter materials: they may be hydrocarbons such as methane, water as liquid or ice, or frozen carbon dioxide.
Fractional melting and crystallization
Magma in the Earth is produced by partial melting of a source rock, ultimately in the mantle. The melt extracts a large portion of the "incompatible elements" from its source that are not stable in the major minerals. When magma rises above a certain depth the dissolved minerals start to crystallize at particular pressures and temperatures. The resulting solids remove various elements from the melt, and melt is thus depleted of those elements. Study of trace elements in igneous rocks thus gives us information about what source melted by how much to produce a magma, and which minerals have been lost from the melt.
Thermal diffusion
When material is unevenly heated, lighter material migrates toward hotter zones and heavier material migrates towards colder areas, which is known as thermophoresis, thermomigration, or the Soret effect. This process can affect differentiation in magma chambers. A deeper understanding of this process can be drawn back to a study done on the Hawaiian lava lakes. The drilling of these lakes led to the discovery of crystals formed within magma fronts. The magma containing concentrations of these large crystals or phenocrysts demonstrated differentiation through the chemical melt of crystals.
Lunar KREEP
On the Moon, a distinctive basaltic material has been found that is high in "incompatible elements" such as potassium, rare earth elements, and phosphorus and is often referred to by the abbreviation KREEP. It is also high in uranium and thorium. These elements are excluded from the major minerals of the lunar crust which crystallized out from its primeval magma ocean, and the KREEP basalt may have been trapped as a chemical differentiate between the crust and the mantle, with occasional eruptions to the surface.
Differentiation through collision
Earth's Moon probably formed out of material splashed into orbit by the impact of a large body into the early Earth. Differentiation on Earth had probably already separated many lighter materials toward the surface, so that the impact removed a disproportionate amount of silicate material from Earth, and left the majority of the dense metal behind. The Moon's density is substantially less than that of Earth, due to its lack of a large iron core. On Earth, physical and chemical differentiation processes led to a crustal density of approximately 2700 kg/m3 compared to the 3400 kg/m3 density of the compositionally different mantle just below, and the average density of the planet as a whole is 5515 kg/m3.
Core formation mechanisms
Core formation utilizes several mechanisms in order to control the movement of metals into the interior of a planetary body. Examples include percolation, diking, diapirism, and the direct delivery of impacts are mechanisms involved in this process. The metal to silicate density difference causes percolation or the movement of a metal downward. Diking is a process in which a new rock formation forms within a fracture of a pre-existing rock body. For example, if minerals are cold and brittle, transport can occur through fluid cracks. A sufficient amount of pressure must be met for a metal to successfully travel through the fracture toughness of the surrounding material. The size of the metal intruding and the viscosity of the surrounding material determines the rate of the sinking process. The direct delivery of impacts occurs when an impactor of similar proportions strikes the target planetary body. During the impact, there is an exchange of pre-existing cores containing metallic material.
The planetary differentiation event is said to have most likely happened after the accretion process of either the asteroid or a planetary body. Terrestrial bodies and iron meteorites consist of Fe-Ni alloys. The Earth's core is primarily composed Fe-Ni alloys. Based on the studies of short lived radionuclides, the results suggest that core formation process occurred during an early stage of the solar system. Siderophile elements such as, sulfur, nickel, and cobalt can dissolve in molten iron; these elements help the differentiation of iron alloys.
The first stages of accretion set up the groundwork for core formation. First, terrestrial planetary bodies enter a neighboring planet's orbit. Next, a collision would take place and the terrestrial body could either grow or shrink. However, in most cases, accretion requires multiple collisions of similar sized objects to have a major difference in the planet's growth. Feeding zones and hit and run events are characteristics that can result after accretion.
See also
Core–mantle differentiation
Iron catastrophe
Rain-out model
References
Planetary science | Planetary differentiation | Astronomy | 1,807 |
25,495,807 | https://en.wikipedia.org/wiki/Solar%20eclipse%20of%20October%2015%2C%202069 | A partial solar eclipse will occur at the Moon's ascending node of orbit on Tuesday, October 15, 2069, with a magnitude of 0.5298. 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. A partial solar eclipse occurs in the polar regions of the Earth when the center of the Moon's shadow misses the Earth.
The partial solar eclipse will be visible for much of Antarctica.
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 2069
A partial solar eclipse on April 21.
A total lunar eclipse on May 6.
A partial solar eclipse on May 20.
A partial solar eclipse on October 15.
A total lunar eclipse on October 30.
Metonic
Preceded by: Solar eclipse of December 27, 2065
Followed by: Solar eclipse of August 3, 2073
Tzolkinex
Preceded by: Solar eclipse of September 3, 2062
Followed by: Solar eclipse of November 26, 2076
Half-Saros
Preceded by: Lunar eclipse of October 9, 2060
Followed by: Lunar eclipse of October 21, 2078
Tritos
Preceded by: Solar eclipse of November 16, 2058
Followed by: Solar eclipse of September 13, 2080
Solar Saros 125
Preceded by: Solar eclipse of October 4, 2051
Followed by: Solar eclipse of October 26, 2087
Inex
Preceded by: Solar eclipse of November 4, 2040
Followed by: Solar eclipse of September 25, 2098
Triad
Preceded by: Solar eclipse of December 15, 1982
Followed by: Solar eclipse of August 16, 2156
Solar eclipses of 2069–2072
Saros 125
Metonic series
Tritos series
Inex series
References
External links
2069 10 15
2069 in science
2069 10 15
2069 10 15 | Solar eclipse of October 15, 2069 | Astronomy | 509 |
72,731,240 | https://en.wikipedia.org/wiki/Cystinarius | Cystinarius is a genus of fungi in the family Cortinariaceae.
Taxonomy
The genus was created in 2022 when the family Cortinariaceae, which previously contained only the one genus of Cortinarius was reclassified based on genomic data and split into the genera of Cortinarius, Aureonarius, Austrocortinarius, Calonarius, Cystinarius, Hygronarius, Mystinarius, Phlegmacium, Thaxterogaster and Volvanarius.
The genus is further divided with subgenus and section classifications:
Cystinarius subgenus Cystinarius includes the section: Cystinarius.
Cystinarius subgenus Crassi includes the section: Crassi.
Etymology
The name Cystinarius derives from cystidia and Cortinarius. This is in reference to the cystidia found in this genus.
Species
As of January 2023, Species Fungorum lists six accepted species of Cystinarius.
Cystinarius crassus (Fr.) Niskanen & Liimat. (2022)
Cystinarius eutactus (Soop) Niskanen & Liimat. (2022)
Cystinarius paurigarhwalensis (Semwal, Dima & Soop) Niskanen & Liimat. (2022)
Cystinarius rubicundulus (Rea) Niskanen & Liimat. (2022)
Cystinarius rubiginosus (Ammirati, Bojantchev, Niskanen & Liimat.) Liimat. & Niskanen (2022)
Cystinarius subgemmeus (Soop) Niskanen & Liimat. (2022)
References
Agaricales genera
Cortinariaceae | Cystinarius | Biology | 384 |
23,432,134 | https://en.wikipedia.org/wiki/David%20Adler%20Lectureship%20Award | The David Adler Lectureship Award in the Field of Materials Physics is a prize that has been awarded annually by the American Physical Society since 1988. The recipient is chosen for "an outstanding contributor to the field of materials physics, who is noted for the quality of his/her research, review articles and lecturing." The prize is named after physicist David Adler with contributions to the endowment by friends of David Adler and major support from Energy Conversion Devices, Inc., as well as support from the American Physical Society's Division of Materials Physics. The prize includes a $5,000 honorarium.
Recipients
Source: American Physical Society
2024 Nitin Samarth
2023 Elbio Dagotto
2022 Axel Hoffmann
2021 Robert Cava
2020 Chang-Beom Eom
2019 Giulia Galli
2018 Christopher J. Palmstrǿm
2017 Heike E. Riel
2016 Harry A. Atwater
2015 Jacqueline Krim
2014 Paul Canfield
2013 Jean-Luc Bredas
2012 Stuart Parkin
2011 Stephen Pearton
2010 Patricia Thiel
2009 Salvatore Torquato
2008 Karin Rabe
2007 Samuel D. Bader
2006 James R. Chelikowsky
2005 Ramamoorthy Ramesh
2004 Chia-Ling Chien
2003 Ivan K. Schuller
2002 Chris G. Van de Walle
2001 Ellen D. Williams (scientist)
2000 Bertram Batlogg
1999 Leonard C. Feldman
1998 Joe Greene
1997 John D. Joannopoulos
1996 M. Brian Maple
1995 Marc A. Kastner
1994 Max Lagally
1993 Simon C. Moss
1992 Robert A. Street
1991 John R. Smith
1990 Michael Schluter
1989 Robert W. Balluffi
1988 Jan Tauc
See also
Leo Szilard Lectureship Award
List of physics awards
References
External links
David Adler Lectureship Award in the Field of Materials Physics, American Physical Society
Awards of the American Physical Society
Materials science awards
Science lecture series
Recurring events established in 1988
1988 establishments in the United States
Physics events | David Adler Lectureship Award | Materials_science,Technology,Engineering | 390 |
23,647,755 | https://en.wikipedia.org/wiki/Asplenium%20azoricum | Asplenium azoricum is a fern from hybrid origin of the family Aspleniaceae, descendant of the Macaronesian ancestral fern Asplenium anceps. It lives exclusively in the Azores, that is a strict endemic Azorean fern. Its fronds are coriaceous like plastic and its rachis is very thick, dark garnet color and brilliance. A typical feature of this fern, which it shares with all the descendants of A. anceps, is the existence of a small atrium at the base of the medium and lower pinnae geared towards the apex of the frond with one or two sori in its underside.
Habitat
It lives among the stones of the walls of the terraces and in the crevices of volcanic rocks oriented to the north and northwest. Depending on the degree of exposure to the sun, its phenotype changes a lot, becoming more coriaceous the more sunlight it receives.
Distribution
It lives in the nine Azores Islands.
Hybrids
Asplenium azomanes (A. trichomanes ssp. coriaceifolium): allotetraploid hybrid between A. azoricum and A. trichomanes.
References
Azorean ferns database: Asplenium azoricum
Asplenium azoricum in the American Fern Journal
See photos of Asplenium azoricum
More photos of Asplenium azoricum
azoricum
Endemic flora of the Azores
Hybrid plants
Plants described in 1977 | Asplenium azoricum | Biology | 305 |
66,345,891 | https://en.wikipedia.org/wiki/Causal%20pie%20model | In the field of epidemiology, the causal mechanisms responsible for diseases can be understood using the causal pie model.This conceptual model was introduced by Ken Rothman to communicate how constellations of component causes can lead to a sufficient cause to lead to a condition of interest and that reflection on these sets could improve epidemiological study design. A set of proposed causal mechanisms are represented as pie charts where each pie in the diagram represent a theoretical causal mechanism for a given disease, which is also called a sufficient cause. Each pie is made up of many component factors, otherwise known as component causes represented by sectors in the diagram. In this framework, each component cause represents an event or condition required for a given disease or outcome. A component cause that appears in every pie is called a necessary cause as the outcome cannot occur without it.
References
Causal diagrams
Epidemiology | Causal pie model | Environmental_science | 176 |
8,225,223 | https://en.wikipedia.org/wiki/Room%20number | A room number is a number assigned to a room within a building. Its purpose is to identify a particular room, and help building inhabitants locate that room.
Room numbers may consist of three digits, but can be any number of digits. The room number is generally assigned with the first digit indicating the floor on which the room is located.
Numbering systems
Similarly to how house numbering systems vary depending on the region, room numbering systems do too. Some numbering systems inform the floor in which the room is located, but not all.
Floor + one digit
Some places in Brazil use a system in which the floor number is followed by only one number. In this system, apartment 52 is the second apartment on the 5th floor.
Floor + two digits
In many places, the number of a room is determined by the number of the floor followed by two digits that inform the number of the room itself, even if there are fewer than 10 rooms per floor. This system is used in the United States by the University of Hawaiʻi at Mānoa for buildings with fewer than 99 rooms per floor. This way, the 5th's floor 2nd apartment would be number 502.
In Sweden, floor numbers must have two digits, followed by two digits for the room number. Floor numbers start from 10 at ground level, and go down for underground floors, and up for above ground floors. In Sweden, the 5th's floor 2nd apartment would be number 1502.
Italy
In Rome, Italy, some addresses explicitly mention which floor ("piano") the apartment is located at. So an address could read "piano 5, interno 2" for the second apartment in the 5th floor.
References
building
hotel terminology
identifiers
number
Hotel rooms | Room number | Engineering | 346 |
1,339,234 | https://en.wikipedia.org/wiki/Electronic%20skip%20protection | Electronic skip protection is a data buffer system used in some portable compact disc (CD) players and all MiniDisc (MD) units so that audio will not be disrupted if the disk cannot be read due to movement.
Technology
When the buffering circuitry is in operation, the compact disc is read at a fixed read speed or CAV and the content is buffered (with optional ADPCM compression) and fed to RAM within the player. The audio content is read from RAM, optionally decompressed, and then sent to the digital-to-analog converter. When the disc reading is interrupted, the player momentarily reads the data stored in RAM while the tracking circuitry finds the passage prior to the interruption on the CD.
Another method has the disc rotating at variable or CLV speed (the normal rotation method for a CD player), but at a slightly higher speed than with the buffer feature switched off. The buffer method is the same as before.
History
The technology surfaced around 1995 as a physically smaller alternative to the bulky rubber shock absorbers utilized in portable players at the time. It reduced the size of the hitherto bulky players designed for use in moving cars, in particular. Small rubber shock absorbers are still used, but are less effective than the larger pre-1995 ones.
When first introduced, 3 seconds was the maximum buffering time. In 2006, the time generally ranged from 10 seconds to "skip-free", where the player will rarely skip due to a large buffer.
Due to the nature of the ATRAC compression scheme, and to ensure uninterrupted playback in the presence of fragmentation, all MD decks and portables buffered at least 10 seconds when the format was introduced in 1992. , MD units have much bigger buffers.
Flash-based MP3 players with no moving parts do not require electronic skip protection.
Pros
Interruption-free playback.
Cons
Audio quality may be slightly worsened due to compression artifacts when the system is in use. Quality is improved with uncompressed buffering.
Battery life is shortened due to the fixed (CAV) read speed of the disc and power required by the memory.
Older players (1992–1997) had at most half the battery life when the skip protection system was in use.
Players from 1997 onward have more power-efficient skip protection.
Portable players, more so portable CD players but also some portable DVD players, that invariably include an ASP feature (Anti-Skip-protection), struggle with CD-R/RW, DVD-R/RW and DVD+R/RW discs – due to the ASP feature being enabled. This is due to the limited read capability of such write-yourself media discs over retail pressed discs. It is widely believed that the buffer system of the ASP feature conflicts with the limited read capability of such discs. This conflict affects the re-writable formats more so than the write once formats, but can be prevalent with both. It is therefore advisable that if you use write-yourself media often, to look for a portable player that allows ASP to be enabled/disabled. As such read issues are invariably non-existent when the ASP feature is disabled. Using slow burning speeds and high-quality media also helps.
Trade names
"ESP", "Anti-Skip", "Anti-Shock", "Joggable" "G-Protection" (Used by Sony), etc.
References
Audio software
Compact disc | Electronic skip protection | Engineering | 706 |
63,885,468 | https://en.wikipedia.org/wiki/DreamLab | DreamLab is a volunteer computing Android and iOS app launched in 2015 by Imperial College London and the Vodafone Foundation.
Description
The app currently helps to research cancer, COVID-19, new drugs and tropical cyclones. To do this, DreamLab accesses part of the device's processing power, with the user's consent, while the owner is charging their smartphone, to speed up the calculations of the algorithms from Imperial College London.
The aim of the tropical cyclone project is to prepare for climate change risks. Other projects aim to find existing drugs and food molecules that could help people with COVID-19 and other diseases. The performance of 100,000 smartphones would reach the annual output of all research computers at Imperial College in just three months, with a nightly runtime of six hours.
The app was developed in 2015 by the Garvan Institute of Medical Research in Sydney and the Vodafone Foundation. As of May 2020, the project had over 490,000 registered users.
See also
Volunteer computing
Folding@home
BOINC
References
External links
Volunteer computing projects
Application software
Medical research
Medical research organizations
Protein structure
Bioinformatics software
Vodafone | DreamLab | Chemistry,Technology,Biology | 238 |
1,256,923 | https://en.wikipedia.org/wiki/Stratovision | Stratovision was an airborne television transmission relay system using aircraft flying at high altitudes. In 1945 the Glenn L. Martin Company and Westinghouse Electric Corporation originally proposed television coverage of small towns and rural areas, as well as the large metropolitan centers, by fourteen aircraft that would provide coverage for approximately 78% of the people in the United States. Although this was never implemented, the system has been used for domestic broadcasting in the United States, and by the U.S. military in South Vietnam and other countries.
Technology
Because the broadcasting antenna for Stratovision is usually hung beneath the aircraft in flight, it naturally has a great command of line-of-sight propagation. Although transmission distances are dependent upon atmospheric conditions, a transmitting antenna above the Earth's surface has a line of sight distance of approximately .
A Stratovision 25 kW transmitter operating from at 600 MHz will achieve a field intensity of 2 millivolts per meter for a high receiving antenna up to away from the aircraft.
Early tests
Stratovision tests were undertaken between June 1948 to February 1949. The first phase was undertaken by the Glenn L. Martin Co. and Westinghouse using a twin-engine PV-2 aircraft flying at that transmitted with 250 watts on 107.5 MHz and 5 kW on 514 MHz at Baltimore, Maryland so that recordings could be made at various locations ranging from Norfolk, Virginia to Pittsburgh, Pennsylvania and Boston, Massachusetts.
The second phase of testing was undertaken by these companies using a stripped-down B-29 Superfortress flying at . The plane was equipped to receive a relay transmission from WMAR-TV in Baltimore, which was then relayed over a 5 kW video transmitter and a 1 kW audio transmitter for reception on 82-88 MHz with a television set tuned to Channel 6.
The aircraft received its originating signals from circular dipoles attached to a streamlined eight-foot (2.5 m) mast atop of the aircraft's vertical tail fin. The retractable long broadcasting antenna hung vertically beneath the aircraft. It was composed of a two-element turnstile array for video and a single-element circular dipole for sound transmissions.
The receivers, transmitters and necessary air-conditioning were all powered by the plane's engines using three 15 kVA, 500 Hz alternators. Without air conditioning the transmitters in the interior of the aircraft would have generated a temperature of 134 degrees Fahrenheit (57 degrees Celsius) with an outside air temperature of 25 degrees Fahrenheit (minus 4 degrees Celsius).
On 23 June 1948 the system's airborne transmitter rebroadcast the Republican National Convention, being held in Philadelphia, Pennsylvania, to the surrounding nine-state area during the 9 to 10 pm EDT time period. As part of the activity, a receiver was set up in a hall in Zanesville, Ohio, a small city on the outskirts of the broadcast area, to demonstrate to invited newspaper reporters that the system was capable of reaching "small town and farm homes".
The tests were watched by many television viewers who sent in reception reports. From these reports it was calculated that Stratovision would require only eight relay planes to provide a transcontinental network, and six additional planes to provide coverage to 78% of the United States. Charles Edward Nobles, the head of Stratovision for Westinghouse, said in his report:
"The major technical problems of the system have been solved, and the commercial development awaits only the crystallization of public demand for the expanded services offered by airborne broadcasting, application of the system by the radio industry to meet this demand, and the clarification of channel facilities available to make possible this application."
Sports
On September 30, 1954, Cuba used a DC-3 to broadcast a baseball championship game from the United States, the first live extracontinental broadcast.
Education
In 1961 a nonprofit organization, Midwest Program on Airborne Television Instruction, commenced a Stratovision service from the airfield of Purdue University. The effort began as a three-year experiment funded by the Ford Foundation. The program organized, produced and transmitted educational television programs four days a week from a DC-6AB aircraft flying at over the community of Montpelier in north central Indiana.
MPATI delivered its programs to television channels 72 (call sign KS2XGA) and 76 (KS2XGD) in the UHF band, by transmitting videotaped lectures from the aircraft to an estimated potential 5,000,000 students in 13,000 schools and colleges. The aircraft were equipped with two videotape machines and two UHF transmitters.
When MPATI signed on it used an "Indian head" test pattern card which was shown for five minutes before and between programs. The service ended in 1968 when it became embroiled in legal action over their application of Stratovision in a controversy with the Westinghouse company.
Propaganda
Vietnam War
During the Vietnam War, the United States Navy used Stratovision television technology when it flew Operation Blue Eagle from 1966 to 1972 over the Saigon area of South Vietnam. The television programs were aimed at two audiences on two channels: one was aimed at the general public and the other was intended for the information and entertainment of US troops who were stationed in South Vietnam.
On January 3, 1966, a Broadcasting magazine article, "Vietnam to get airborne TV: Two-channel service —one for Vietnamese, other for U.S. servicemen—starts this month", noted:
Television broadcasting in South Vietnam ... begins January 21 and it's going to be done from the air. Two airplanes, circling above the ground, will broadcast on two TV channels—one transmitting Saigon government programs; the other U.S. programs. The project is being handled by the U.S. Navy. Also involved are the U.S. Information Agency and the Agency for International Development. Work on modifying two Lockheed Super Constellations has been underway by Navy electronics experts at Andrews Air Force Base ... The project is an outgrowth of a broadcasting plane used by the Navy during the Cuban and Dominican Republic crises when both radio and television were beamed to home in those countries.
The same article went on to report that during the Baseball World Series of October 1965 Stratovision had also been used to bring the games to the troops. The aircraft had picked up Voice of America radio broadcasts from California and relayed the signal to a ground broadcasting station. The Agency for International Development (AID) had purchased through the military Post Exchange Service, 1,000 monochrome, 23-inch television sets modified to operate on a variety of domestic power sources, and which had been airlifted to South Vietnam on December 28, 1965. They were to be put into community facilities around Saigon. AID was also spending $2.4 million to supply a total of 2,500 TV sets to South Vietnam.
The entire project was under the control of Captain George C. Dixon, USN. He claimed to be installing AM, FM, shortwave and TV transmitters on the aircraft which would get their power from an onboard 100 kW diesel-fueled generator. The planes would not only relay programs from film chain kinescopes and video recorders, but they would also have live cameras to create their own live programs.
Ground transmissions would be received from the aircraft on TV sets tuned to channel 11 for Armed Forces Television, and channel 9 for programs in Vietnamese. On radio the broadcasts would be tuned to 1000 kHz for AM and 99.9 MHz for FM.
On 7 February 1966, Broadcasting magazine reported that after working out a number of technical problems that the first show on channel 9 would begin at 7:30 p.m. and feature South Vietnamese Prime Minister Nguyen Cao Ky and U.S. Ambassador Henry Cabot Lodge in a videotaped production, followed by channel 11 at 8 p.m. with General Westmoreland introducing a two-hour program which incorporated one hour of the Grand Ole Opry filmed in Nashville, Tennessee. After that the Vietnamese channel would be seen for one and half hours a day and the U.S. channel for three hours daily.
On 8 February 1966 The New York Times article "South Vietnamese Watch First TV Show" reported that South Vietnamese viewers had to strain their ears because the speakers on the TV sets would need to be amplified if they were going to be heard by a room full of people watching THVN-TV channel 9. The U.S. programming on NWB-TV channel 11 was Bob Hope in a two-hour special called Hollywood Salute to Vietnam, followed by half-an-hour of the Grand Ole Opry and another half-hour of the quiz show I've Got a Secret. The regular line-up of shows included Bonanza, Perry Mason, The Ed Sullivan Show, and The Tonight Show Starring Johnny Carson.
1999 NATO bombing of the Federal Republic of Yugoslavia
EC-130 Commando Solo was used in propaganda warfare during the 1999 NATO bombing of the Federal Republic of Yugoslavia with questionable success. Production was very cheap, below local TV standards in Federal Republic of Yugoslavia with slide show and narration based news. Quality of reception was very poor and area of coverage was rather small.
Iraq War
During the 2000s, the EC-130 Commando Solo has been used to broadcast information and propaganda for the United States over a variety of television and radio frequencies. It has been used in several areas of operation, including Bosnia and Iraq.
Pirate television
In 1969, news stories began to appear in the United Kingdom that Ronan O'Rahilly, the founder of the pirate radio ship based service called Radio Caroline, which at that time was not on the air, was about to launch Caroline Television instead. His plans called for two aircraft, one in service and one as a relief, which would transmit commercial television programs to Britain by Stratovision. Although these stories continued for some time, nothing became of the project. To date no pirate radio or television service has ever operated by means of Stratovision.
Use as a temporary service
The advent of fibre optic cable television systems and direct broadcast satellite services has supplanted Stratovision as a permanent means of television delivery. The Stratovision concept continues to be used as a stop-gap measure where land-based transmitters are not possible and where large areas of territory need to be served with a television program.
Popular culture
The plot of the 1986 comedy film Riders of the Storm (also known as The American Way) is based on a similar concept, with a group of Vietnam veterans running a pirate television station ("S&M TV") from a B-29 that was constantly in flight.
A similar system, using helicopters, is mentioned in the 1950 Robert A. Heinlein story "The Man Who Sold the Moon".
References
External links
American inventions
1948 establishments in the United States
Telecommunications-related introductions in the 1940s
Television technology
Propaganda in the United States
Educational television | Stratovision | Technology | 2,214 |
51,011,418 | https://en.wikipedia.org/wiki/Swimsuits%20For%20All | Swimsuits For All is an online retailer for women's swimwear, specializing in sizes 4 and up. It was founded in 2005 by current CEO and President Moshe Laniado, and was acquired in October 2014 by New York-based plus size fashion company, Fullbeauty Brands.
Press campaigns
In May 2013, Swimsuits For All introduced a “fatkini” collection, mutually designed with plus-size fashion blogger Gabi Gregg, who coined the term and popularized curvy bikinis. The collection of plus size swimsuits sold out in 48 hours. In February 2015, the plus size swimwear retailer launched its #CurvesInBikinis campaign, which quickly went viral and starred Ashley Graham as the first plus-size model featured in an ad in the Sports Illustrated Swimsuit Issue. Swimsuits For All announced its exclusive partnership with Ashley Graham in December 2015 to make her the face of the brand, and in May 2016, the two launched their first joint swimwear collection, Ashley Graham x Swimsuits For All. In April 2019, plus-size model Ashley Graham and comedian Sherri Shepherd joined Kelvin Davis for a swimsuit campaign. The campaign featured a video commercial.
References
Online clothing retailers of the United States
Sizes in clothing
Swimwear manufacturers
Companies that filed for Chapter 11 bankruptcy in 2019 | Swimsuits For All | Physics,Mathematics | 268 |
78,153,053 | https://en.wikipedia.org/wiki/1ES%201959%2B650 | 1ES 1959+650 is a BL Lacertae object or a BL Lac object located in the eastern constellation of Draco, about 676 million light years from Earth. It was first discovered as an astronomical radio source in 1987 by Green Bank Radio Telescope and further categorized as both a flat-spectrum radio source and an X-ray source during the Einstein IPC Slew Survey conducted in the early 1990s.
Characteristics
1ES 1959+650 has an active galactic nucleus. It is classified as a high energy-peaked BL Lac object or a synchrotron peaked blazar with a synchrotron peak of the spectral energy distribution appearing in ultraviolet and X-ray bands.
The host galaxy of 1ES 1959+650 is a gas-rich elliptical galaxy with a dust lane located 0.8" north of its nucleus. Its structure is complex, indicating a past galaxy merger. The supermassive black hole in the center of 1ES 1959+650 is estimated to be ~ 1.3 x 108 Mʘ.
1ES 1959+650 is violently variable. It exhibits multiple outburst episodes across its electromagnetic spectrum, In its low flux state between 2000 and 2001, 1ES 1959+650 was observed with HEGRA Atmospheric Cherenkov Telescope system, which it showed a Crab flux of 5.3%. During its flaring state in May 2002, the blazar's flux level increased significantly as high as 2.2 Crab. Furthermore, an orphan flare, not accompanied by increasing activity in spectral bands, was also shown. The gamma emission in 1ES 1959+650 displays 'softer-when-brighter' evolution in a 0.1-300 GeV band while the X-ray emission showed 'harder-when-brighter' evolution in a 0.6-10 KeV band.
In addition to its variability, 1ES 1959+650 shows gamma ray flares from short to long timescales. X-ray flares were also detected in the blazar, apart from gamma ray flares. Between August 2015 and January 2016, a powerful and prolonged X-ray flare was detected in 1ES 1959+650. That same year, the second strongest X-ray flare occurred with a 5.5 month interval separation after the first flare.
The source in 1ES 1959+650 is unresolved on a kiloparsec scale. By looking at a parsec scale, it is found to be dominated by a luminous core. There is also presence of some extended unpolarized emission to the north, which the electric vector position angle is found parallel to it while the core polarization on the other hand, is roughly 1.5 percent. This suggests a component emerging towards north with average polarization of 4 percent.
References
External links
1ES 1959+650 on SIMBAD
BL Lacertae objects
Draco (constellation)
Blazars
Active galaxies
2674942
Astronomical objects discovered in 1987 | 1ES 1959+650 | Astronomy | 598 |
52,048,251 | https://en.wikipedia.org/wiki/Pistol%20ribozyme | The pistol ribozyme is an RNA structure that catalyzes its own cleavage at a specific site. In other words, it is a self-cleaving ribozyme. The pistol ribozyme was discovered through comparative genomic analysis.
Subsequent biochemical analysis determined further biochemical characteristics of the ribozyme. This understanding was further advanced by an atomic-resolution crystal structure of a pistol ribozyme
Discovery
Pistol ribozyme was discovered by a bioinformatics strategy as an RNA Associated with Genes Associated with Twister and Hammerhead ribozymes, or RAGATH.
Physical Properties
Comparative analysis of 501 unique samples of pistol ribozyme from ribozyme-associated gene classes and bacterial DNA sequences was done to reach a consensus of the physical properties of the pistol ribozyme
Sequences
10 nucleotides were discovered to be highly conserved amongst many pistol ribozymes: G5, A19, A20, A 21, A31, A32, A33, G40, C41, and G42. Mutation to any of these nucleotides disrupt its secondary structure, which also disrupt its catalytic ability. The scissile bond was also determine to be between G53-U54 located in the junction connecting P2 and P3. Although the identity of these two nucleotides might vary, the length of the junction remains highly conserved.
Secondary Structure
Secondary structure in pistol ribozyme was observed to be highly conserved. There are 3 Watson-Crick base-paired stems: P1, P2, and P3, which are all connected by loops. A pseudoknot interaction exists between the loop of P1 and the junction connecting P2 and P3.
Catalytic Activity
Mechanism
The mechanism for pistol ribozyme was deduced through the identification of the products of the self-cleaving reaction. Through mass spectrometry, it was found that the products contain 5'-hydroxyl and 2',3'-cyclic phosphate functional groups. Reaction mechanism was concluded to involve 2'-OH nucleophilic attack by G53 on the phosphate bond connecting G53-U54. The process involves a trigonal bipyramidal penta-coordinated phosphorus center. N1 on G40 acts a general base in which it activates the nucleophile 2'-OH on G53. G32 acts as a general acid in which it neutralizes the developing negative charge on the intermediate.
Kinetics
Under physiological pH and magnesium ion concentration, the rate constant of pistol ribozyme self-cleaving reaction was observed to be > 10 min−1. Under optimum condition (pH = 7.0 - 9.0, and magnesium concentration above 50 mM), the rate constant detected to be > 100 min−1. As magnesium concentration increases, the rate of reaction increases but starts to plateau around 50 mM.
Metal Ions Specificity
Self-cleaving reactions were observed in the presence of 0.1 mM of various monovalent and divalent metal ions such as magnesium, manganese, calcium, cobalt, nickel, cadmium, barium, sodium, and lithium. This implies that pistol ribozyme possess no specificity in the metal ion required in catalysis.
References
RNA
Ribozymes | Pistol ribozyme | Chemistry | 670 |
5,358,321 | https://en.wikipedia.org/wiki/Far%20EasTone | Far EasTone Telecommunications (Far EasTone/FET; ) is a telecommunications company based in Taiwan. It is the third largest behind Chunghwa Telecom and Taiwan Mobile.
History
Far EasTone was founded in October 1996 by the Far Eastern Group, in a joint venture with AT&T. The company was awarded two wireless (GSM 900 and GSM 1800) service licenses in January 1997. The following year, Far EasTone launched its service and became the first company to introduce a fully integrated dual-band system.
Far EasTone was the first Taiwanese company to offer the Java 32K SIM Toolkit, mobile banking, mobile commerce, real-time access to financial, entertainment and headline news, mobile fax/mail, logo download and e-coupons. In March 1999, after fourteen months in business, Far EasTone achieved one million revenue-producing customers, faster than any other GSM operator.
The company was listed on the Taiwan OTC Stock Exchange in December 2001 under the ticker code 4904 and was officially listed on the Taiwan Stock Exchange in the electronic sector in August 2005. In September 2006, Far EasTone began providing 3G WCDMA services.
On December 16, 2009, Far EasTone acquired WiMAX licenses, and from December 22 began offering WiMAX transmission services. On October 30, 2013, Taiwan's LTE standard license bidding closed with Far EasTone paying NT$31.315 billion for the LTE frequency bands (700 MHz A2/1800 MHz C3, C4), with a total bandwidth of 30 MHz. Far EasTone launched 4G LTE services on June 3, 2014 and 5G NR services in 2020.
List of presidents
Joseph O'Konek (May 1998 – 30 June 2002)
Jan Nilsson (1 September 2002 – September 2010)
Yvonne Li (10 September 2010 – January 2019)
Chee Ching (since 7 January 2019)
Mobile Network Information (Radio Frequency Summary)
Mergers and acquisitions
The parent company of , NTT Docomo, reportedly proposed in 2003 that KG Telecom and Far EasTone swap shares in a merger. A deal was reached in that July, only to fall through in August. Another round of negotiations produced a second agreement in October 2003. In April 2004, the merger was finalized, and became the largest ever acquisition in the Taiwanese telecom industry. In February 2005, Far EasTone bought a 55.3% stake in Arcoa. In May 2005, Far EasTone formally merged with Yuan-Ze Telecom. In May 2007, the company bought a 51% equity interest in Q-ware Communications to extend the scope of its wireless communications services.
In August 2007, Singtel transferred its 24.5% stake in New Century Infocomm Tech company for a 3.5% share of Far EasTone. On April 30, 2009, it was announced that China Mobile would invest up to 12 per cent into the company. The amount of foreign ownership was projected to be: NTT DoCoMo at 4.1 per cent, SingTel at 3.5 per cent, China Mobile at 12 per cent. On April 27, 2012, Singtel sold its 3.98% share of Far EasTone. On April 18, 2013, China Mobile announced the termination of a stake in Far EasTone, though the parties signed a bilateral cooperation agreement.
According to a July 5, 2015 article in The Wall Street Journal, there was a consortium seeking to buy cable television company from the private equity firm MBK Partners LP, led by the company and Morgan Stanley.
FarEasTone announced in February 2022 that the company would acquire in a stock swap, resulting on the merger between two telecom.
Subscribers and market share
The total number of subscribers between the Company and KGT was 6.13 million at the end of December 2008. In the Taiwan mobile market (2 & 3G) the market shares were as follows: Chunghwa Telecom at 35%, Taiwan Mobile at 25%, Far EasTone at 24%, Asia Pacific Telecom and Vibo Telecom at 10%, and PHS at 6%. The company, along with other leading Taiwan companies, has recently (April 29, 2016) been raising prices.
See also
List of companies of Taiwan
References
External links
Members of the Conexus Mobile Alliance
Companies listed on the Taiwan Stock Exchange
Companies based in Taipei
Mobile phone companies of Taiwan
Telecommunications companies of Taiwan
Taiwanese brands
Telecommunications companies established in 1997
1997 establishments in Taiwan
Far Eastern Group | Far EasTone | Technology | 898 |
4,393,727 | https://en.wikipedia.org/wiki/Stokes%20relations | In physical optics, the Stokes relations, named after Sir George Gabriel Stokes, describe the relative phase of light reflected at a boundary between materials of different refractive indices. They also relate the transmission and reflection coefficients for the interaction. Their derivation relies on a time-reversal argument, so they only work when there is no absorption in the system.
A reflection of the incoming field (E) is transmitted at the dielectric boundary to give rE and tE (where r and t are the amplitude reflection and transmission coefficients, respectively). Since there is no absorption this system is reversible, as shown in the second picture (where the direction of the beams has been reversed). If this reversed process were actually taking place, there will be parts of the incoming fields (rE and tE) that are themselves transmitted and reflected at the boundary. In the third picture, this is shown by the coefficients r' and t' (for reflection and transmission of the reversed fields). Everything must interfere so that the second and third pictures agree; beam x has amplitude E and beam y has amplitude 0, providing Stokes relations.
The most interesting result here is that r=-r’. Thus, whatever phase is associated with reflection on one side of the interface, it is 180 degrees different on the other side of the interface. For example, if r has a phase of 0, r’ has a phase of 180 degrees.
Explicit values for the transmission and reflection coefficients are provided by the Fresnel equations
References
Optics | Stokes relations | Physics,Chemistry | 304 |
7,529,097 | https://en.wikipedia.org/wiki/Vaginal%20dilator | A vaginal dilator (sometimes called a vaginal trainer) is an instrument used to gently stretch the vagina. They are used when the vagina has become narrowed (vaginal stenosis), such as after brachytherapy for gynecologic cancers, and as therapy for vaginismus and other forms of dyspareunia.
There is evidence for dilator use across many different diagnoses with fair to good results. This includes following cancer treatments and for vaginal agenesis conditions. The evidence presents varying approaches and protocols.
Vaginal dilators, also called vaginal stents or vaginal expanders, can be inflatable and are used during surgeries. Vaginal stents are routinely used in postoperative care for transgender patients who have undergone vaginoplasty as part of gender confirmation surgery. They are also used for various conditions, such as vaginal agenesis. The vaginal expander is used immediately after surgery to keep the passage from collapsing, and regularly thereafter to maintain the viability of the neovagina. Frequency of use requirements decrease over time, but remains obligatory lifelong.
Use
With solid vaginal dilators, the patient starts with the smallest dilator size, then gradually increasing until the largest dilator size is reached. This practice can be accompanied by breathing exercises in order to relax the pelvic floor muscles. Dilation acts should not cause pain or bleeding. Dilatation with rigid dilators must be done carefully as vaginal perforation and urethral injury may occur. There is no consensus on the frequency and duration of using vaginal dilators. In case of vaginal expanders, the therapist or the patient introduces the deflated balloon into the vagina and then inflates it gently until the required diameter is obtained.
Image gallery
In popular culture
Vaginal dilators appear in the comedy feature film Lady Parts, as the main character struggles with vaginismus after receiving a vestibulectomy.
See also
Dilator
Dildo
Rectal dilator
References
Gynaecology
Medical equipment | Vaginal dilator | Biology | 425 |
1,516,500 | https://en.wikipedia.org/wiki/Chemical%20file%20format | A chemical file format is a type of data file which is used specifically for depicting molecular data. One of the most widely used is the chemical table file format, which is similar to Structure Data Format (SDF) files. They are text files that represent multiple chemical structure records and associated data fields. The XYZ file format is a simple format that usually gives the number of atoms in the first line, a comment on the second, followed by a number of lines with atomic symbols (or atomic numbers) and cartesian coordinates. The Protein Data Bank Format is commonly used for proteins but is also used for other types of molecules. There are many other types which are detailed below. Various software systems are available to convert from one format to another.
Distinguishing formats
Chemical information is usually provided as files or streams and many formats have been created, with varying degrees of documentation. The format is indicated in three ways:(see )
file extension (usually 3 letters). This is widely used, but fragile as common suffixes such as .mol and .dat are used by many systems, including non-chemical ones.
self-describing files where the format information is included in the file. Examples are CIF and CML.
chemical/MIME type added by a chemically aware server.
Chemical Markup Language
Chemical Markup Language (CML) is an open standard for representing molecular and other chemical data. The open source project includes XML Schema, source code for parsing and working with CML data, and an active community. The articles Tools for Working with Chemical Markup Language and XML for Chemistry and Biosciences discusses CML in more detail. CML data files are accepted by many tools, including JChemPaint, Jmol, XDrawChem and MarvinView.
Protein Data Bank Format
The Protein Data Bank Format is an obsolete format for protein structures developed in 1972. It is a fixed-width format and thus limited to a maximum number of atoms, residues, and chains; this resulted in splitting very large structures such as ribosomes into multiple files. For example, the E. coli 70S was represented as 4 PDB files in 2009: 3I1M , 3I1N , 3I1O, and 3I1P. In 2014, they were consolidated into a single file, 4V6C.
In 2014, the PDB format was officially replaced with mmCIF, and newer PDB structures may not have PDB files available.
Some PDB files contained an optional section describing atom connectivity as well as position. Because these files were sometimes used to describe macromolecular assemblies or molecules represented in explicit solvent, they could grow very large and were often compressed. Some tools, such as Jmol and KiNG, could read PDB files in gzipped format. The wwPDB maintained the specifications of the PDB file format and its XML alternative, PDBML. There was a fairly major change in PDB format specification (to version 3.0) in August 2007, and a remediation of many file problems in the existing database. The typical file extension for a PDB file was .pdb, although some older files used .ent or .brk. Some molecular modeling tools wrote nonstandard PDB-style files that adapted the basic format to their own needs.
GROMACS format
The GROMACS file format family was created for use with the molecular simulation software package GROMACS. It closely resembles the PDB format but was designed for storing output from molecular dynamics simulations, so it allows for additional numerical precision and optionally retains information about particle velocity as well as position at a given point in the simulation trajectory. It does not allow for the storage of connectivity information, which in GROMACS is obtained from separate molecule and system topology files. The typical file extension for a GROMACS file is .gro.
CHARMM format
The CHARMM molecular dynamics package can read and write a number of standard chemical and biochemical file formats; however, the CARD (coordinate) and PSF (protein structure file) are largely unique to CHARMM. The CARD format is fixed-column-width, resembles the PDB format, and is used exclusively for storing atomic coordinates. The PSF file contains atomic connectivity information (which describes atomic bonds) and is required before beginning a simulation. The typical file extensions used are .crd and .psf respectively.
GSD format
The General Simulation Data (GSD) file format created for efficient reading / writing of generic particle simulations, primarily - but not restricted to - those from HOOMD-blue. The package also contains a python module that reads and writes HOOMD schema gsd files with an easy to use syntax.
Ghemical file format
The Ghemical software can use OpenBabel to import and export a number of file formats. However, by default, it uses the GPR format. This file is composed of several parts, separated by a tag (!Header, !Info, !Atoms, !Bonds, !Coord, !PartialCharges and !End).
The proposed MIME type for this format is application/x-ghemical.
SYBYL Line Notation
SYBYL Line Notation (SLN) is a chemical line notation. Based on SMILES, it incorporates a complete syntax for specifying relative stereochemistry. SLN has a rich query syntax that allows for the specification of Markush structure queries. The syntax also supports the specification of combinatorial libraries of ChemDraw.
{| class="wikitable"
|+Example SLNs
! Description
! SLN string
|-
| Benzene
| C[1]H:CH:CH:CH:CH:CH:@1
|-
| Alanine
| NH2C[s=n]H(CH3)C(=O)OH
|-
| Query showing R sidechain
| R1[hac>1]C[1]:C:C:C:C:C:@1
|-
| Query for amide/sulfamide
| NHC=M1{M1:O,S}
|}
SMILES
The simplified molecular input line entry system, or SMILES, is a line notation for molecules. SMILES strings include connectivity but do not include 2D or 3D coordinates.
Hydrogen atoms are not represented. Other atoms are represented by their element symbols B, C, N, O, F, P, S, Cl, Br, and I. The symbol = represents double bonds and # represents triple bonds. Branching is indicated by ( ). Rings are indicated by pairs of digits.
Some examples are
{| class="wikitable"
|-
! Name
! Formula
! SMILES string
|-
| Methane
| CH4
| C
|-
| Ethanol
| C2H6O
| CCO
|-
| Benzene
| C6H6
| C1=CC=CC=C1 or c1ccccc1
|-
| Ethylene
| C2H4
| C=C
|}
XYZ
The XYZ file format is a simple format that usually gives the number of atoms in the first line, a comment on the second, followed by a number of lines with atomic symbols (or atomic numbers) and cartesian coordinates.
MDL number
The MDL number contains a unique identification number for each reaction and variation. The format is RXXXnnnnnnnn. R indicates a reaction, XXX indicates which database contains the reaction record. The numeric portion, nnnnnnnn, is an 8-digit number.
Other common formats
One of the most widely used industry standards are chemical table file formats, like the Structure Data Format (SDF) files. They are text files that adhere to a strict format for representing multiple chemical structure records and associated data fields. The format was originally developed and published by Molecular Design Limited (MDL). MOL is another file format from MDL. It is documented in Chapter 4 of CTfile Formats.
PubChem also has XML and ASN1 file formats, which are export options from the PubChem online database. They are both text based (ASN1 is most often a binary format).
There are a large number of other formats listed in the table below
Converting between formats
OpenBabel and JOELib are freely available open source tools specifically designed for converting between file formats. Their chemical expert systems support a large atom type conversion tables.
obabel -i input_format input_file -o output_format output_file
For example, to convert the file epinephrine.sdf in SDF to CML use the command
obabel -i sdf epinephrine.sdf -o cml epinephrine.cml
The resulting file is epinephrine.cml.
IOData is a free and open-source Python library for parsing, storing, and converting various file formats commonly used by quantum chemistry, molecular dynamics, and plane-wave density-functional-theory software programs. It also supports a flexible framework for generating input files for various software packages. For a complete list of supported formats, please go to https://iodata.readthedocs.io/en/latest/formats.html.
A number of tools intended for viewing and editing molecular structures are able to read in files in a number of formats and write them out in other formats. The tools JChemPaint (based on the Chemistry Development Kit), XDrawChem (based on OpenBabel), Chime, Jmol, Mol2mol and Discovery Studio fit into this category.
The Chemical MIME Project
"Chemical MIME" is a de facto approach for adding MIME types to chemical streams.
This project started in January 1994, and was first announced during the Chemistry workshop at the First WWW International Conference, held at CERN in May 1994. ... The first version of an Internet draft was published during May–October 1994, and the second revised version during April–September 1995. A paper presented to the CPEP (Committee on Printed and Electronic Publications) at the IUPAC meeting in August 1996 is available for discussion.
In 1998 the work was formally published in the JCIM.
{| class="wikitable"
! File extension
! MIME Type
! Proper Name
! Description
|-
| .alc
| chemical/x-alchemy
| Alchemy Format
|
|-
| .csf
| chemical/x-cache-csf
| CAChe MolStruct CSF
|
|-
| .cbin, .cascii, .ctab
| chemical/x-cactvs-binary
| CACTVS format
|
|-
| .cdx
| chemical/x-cdx
| ChemDraw eXchange file
|
|-
| .cer
| chemical/x-cerius
| MSI Cerius II format
|
|-
| .c3d
| chemical/x-chem3d
| Chem3D Format
|
|-
| .chm
| chemical/x-chemdraw
| ChemDraw file
|
|-
| .cif
| chemical/x-cif
| Crystallographic Information File, Crystallographic Information Framework
| Promulgated by the International Union of Crystallography
|-
| .cmdf
| chemical/x-cmdf
| CrystalMaker Data format
|
|-
| .cml
| chemical/x-cml
| Chemical Markup Language
| XML based Chemical Markup Language.
|-
| .cpa
| chemical/x-compass
| Compass program of the Takahashi
|
|-
| .bsd
| chemical/x-crossfire
| Crossfire file
|
|-
| .csm, .csml
| chemical/x-csml
| Chemical Style Markup Language
|
|-
| .ctx
| chemical/x-ctx
| Gasteiger group CTX file format
|
|-
| .cxf, .cef
| chemical/x-cxf
| Chemical eXchange Format
|
|-
| .emb, .embl
| chemical/x-embl-dl-nucleotide
| EMBL Nucleotide Format
|
|-
| .spc
| chemical/x-galactic-spc
| SPC format for spectral and chromatographic data
|
|-
| .inp, .gam, .gamin
| chemical/x-gamess-input
| GAMESS Input format
|
|-
| .fch, .fchk
| chemical/x-gaussian-checkpoint
| Gaussian Checkpoint Format
|
|-
| .cub
| chemical/x-gaussian-cube
| Gaussian Cube (Wavefunction) Format
|
|-
| .gau, .gjc, .gjf, .com
| chemical/x-gaussian-input
| Gaussian Input Format
|
|-
| .gcg
| chemical/x-gcg8-sequence
| Protein Sequence Format
|
|-
| .gen
| chemical/x-genbank
| ToGenBank Format
|
|-
| .istr, .ist
| chemical/x-isostar
| IsoStar Library of Intermolecular Interactions
|
|-
| .jdx, .dx
| chemical/x-jcamp-dx
| JCAMP Spectroscopic Data Exchange Format
|
|-
| .kin
| chemical/x-kinemage
| Kinetic (Protein Structure) Images; Kinemage
|
|-
| .mcm
| chemical/x-macmolecule
| MacMolecule File Format
|
|-
| .mmd, .mmod
| chemical/x-macromodel-input
| MacroModel Molecular Mechanics
|
|-
| .mol
| chemical/x-mdl-molfile
| MDL Molfile
|
|-
| .smiles, .smi
| chemical/x-daylight-smiles
| Simplified molecular input line entry specification
| A line notation for molecules.
|-
| .sdf
| chemical/x-mdl-sdfile
| Structure-Data File
|
|-
| .el
| chemical/x-sketchel
| SketchEl Molecule
|
|-
| .ds
| chemical/x-datasheet
| SketchEl XML DataSheet
|
|-
| .inchi
| chemical/x-inchi
| IUPAC International Chemical Identifier (InChI)
|
|-
| .jsd, .jsdraw
| chemical/x-jsdraw
| JSDraw native file format
|
|-
| .helm, .ihelm
| chemical/x-helm
| Pistoia Alliance HELM string
| A line notation for biological molecules
|-
| .xhelm
| chemical/x-xhelm
| Pistoia Alliance XHELM XML file
| XML based HELM including monomer definitions
|}
Support
For Linux/Unix, configuration files are available as a "chemical-mime-data" package in .deb, RPM and tar.gz formats to register chemical MIME types on a web server. Programs can then register as viewer, editor or processor for these formats so that full support for chemical MIME types is available.
Sources of chemical data
Here is a short list of sources of freely available molecular data. There are many more resources than listed here out there on the Internet. Links to these sources are given in the references below.
The US National Institute of Health PubChem database is a huge source of chemical data. All of the data is in two-dimensions. Data includes SDF, SMILES, PubChem XML, and PubChem ASN1 formats.
The worldwide Protein Data Bank (wwPDB) is an excellent source of protein and nucleic acid molecular coordinate data. The data is three-dimensional and provided in Protein Data Bank (PDB) format.
is a commercial database for molecular data. The data includes a two-dimensional structure diagram and a smiles string for each compound. supports fast substructure searching based on parts of the molecular structure.
ChemExper is a commercial data base for molecular data. The search results include a two-dimensional structure diagram and a mole file for many compounds.
New York University Library of 3-D Molecular Structures.
The US Environmental Protection Agency's The Distributed Structure-Searchable Toxicity (DSSTox) Database Network is a project of EPA's Computational Toxicology Program. The database provides SDF molecular files with a focus on carcinogenic and otherwise toxic substances.
See also
File format
OpenBabel, JOELib, OELib
Chemistry Development Kit
Chemical Markup Language
Software for molecular modeling
NCI/CADD Chemical Identifier Resolver
References
External links | Chemical file format | Chemistry | 3,432 |
24,776,626 | https://en.wikipedia.org/wiki/Karl%20Hult | Karl Hult(born 1944) is a Swedish biochemist and researcher. He is a professor emeritus at the Royal Institute of Technology, Stockholm, Sweden, and has contributed to research within the fields of metabolism and biocatalysis.
Research
Hult's early research was in the field of fungal metabolism, and metabolic studies of Alternaria alternata lead to the discovery of the mannitol cycle.
He also studied the fungal secondary metabolite ochratoxin A, a potential human carcinogen produced by some Aspergillus and Penicillium species.
The last two decades, his research has been in the area of biocatalysis, with an interest in both the fundamental understanding of enzyme function and mechanism as well as more applied research. The work has been centered on the fungal enzyme Pseudozyma (formerly Candida) antarctica lipase B.
Education
197? Master of Science in chemical engineering from the Royal Institute of Technology, Stockholm, Sweden.
1980 PhD in biochemistry
1984 Assistant professor
1985 Associate professor
1986 Professor
References
External links
Key publications
Swedish biochemists
1944 births
Living people | Karl Hult | Chemistry | 225 |
8,292,896 | https://en.wikipedia.org/wiki/Eye%E2%80%93hand%20span | The eye–hand span is the distance across part of a text, usually a linguistic text that is being copied via typing or a piece of notated music that is being performed, defined as the distance between the position of the eyes acquiring that information and the hand(s) typing or performing it. Specifically, the eye–hand span is typically measured from the location of central visual input, and stretches between the syllable or chord currently being typed or performed, and the lateral location of the simultaneous fixation. This distance may be measured either in units of linear measurement or in characters or other "bits" of data. Some authors refer to the eye–hand span as the "perceptual span" for the visual information perceivable around the region of center of vision used in reading, and in some cases including peripheral input. The eye–hand span is analogous to the eye–voice span in reading language aloud and in singing.
See also
Eye movement in language reading
Eye movement in music reading
Hand–eye coordination
References
Reading (process)
Motor control | Eye–hand span | Biology | 214 |
1,456,605 | https://en.wikipedia.org/wiki/Boosted%20Dart | Boosted Dart is a United States single stage sounding rocket of the Loki family. Between 1966 and 1968, 39 of these rockets were launched by NASA. The Boosted Dart has a length of 3.30 meters, a diameter of 0.1 meters and a maximum flight altitude of 75 kilometers.
References
External links
Sounding rockets of the United States | Boosted Dart | Astronomy | 68 |
3,516,071 | https://en.wikipedia.org/wiki/Rig%20standpipe | A rig standpipe is a solid metal pipe attached to the side of a drilling rig's derrick that is a part of its drilling mud system. It is used to conduct drilling fluid from the mud pumps to the kelly hose. Bull plugs, pressure transducers and valves are found on the rig standpipe.
Petroleum production | Rig standpipe | Chemistry | 69 |
23,604,382 | https://en.wikipedia.org/wiki/Bioanalysis | Bioanalysis is a sub-discipline of analytical chemistry covering the quantitative measurement of xenobiotics (drugs and their metabolites, and biological molecules in unnatural locations or concentrations) and biotics (macromolecules, proteins, DNA, large molecule drugs, metabolites) in biological systems.
Modern bioanalytical chemistry
Many scientific endeavors are dependent upon accurate quantification of drugs and endogenous substances in biological samples; the focus of bioanalysis in the pharmaceutical industry is to provide a quantitative measure of the active drug and/or its metabolite(s) for the purpose of pharmacokinetics, toxicokinetics, bioequivalence and exposure–response (pharmacokinetics/pharmacodynamics studies). Bioanalysis also applies to drugs used for illicit purposes, forensic investigations, anti-doping testing in sports, and environmental concerns.
Bioanalysis was traditionally thought of in terms of measuring small molecule drugs. However, the past twenty years has seen an increase in biopharmaceuticals (e.g. proteins and peptides), which have been developed to address many of the same diseases as small molecules. These larger biomolecules have presented their own unique challenges to quantification.
History
The first studies measuring drugs in biological fluids were carried out to determine possible overdosing as part of the new science of forensic medicine/toxicology.
Initially, nonspecific assays were applied to measuring drugs in biological fluids. These were unable to discriminate between the drug and its metabolites; for example, aspirin () and sulfonamides (developed in the 1930s) were quantified by the use of colorimetric assays. Antibiotics were quantified by their ability to inhibit bacterial growth. The 1930s also saw the rise of pharmacokinetics, and as such the desire for more specific assays. Modern drugs are more potent, which has required more sensitive bioanalytical assays to accurately and reliably determine these drugs at lower concentrations. This has driven improvements in technology and analytical methods.
Bioanalytical techniques
Some techniques commonly used in bioanalytical studies include:
Hyphenated techniques
LC–MS (liquid chromatography–mass spectrometry)
GC–MS (gas chromatography–mass spectrometry)
LC–DAD (liquid chromatography–diode array detection)
CE–MS (capillary electrophoresis–mass spectrometry)
Chromatographic methods
HPLC (high performance liquid chromatography)
GC (gas chromatography)
UPLC (ultra performance liquid chromatography)
Supercritical fluid chromatography
Electrophoresis
Ligand binding assays
Dual polarisation interferometry
ELISA (Enzyme-linked immunosorbent assay)
MIA (magnetic immunoassay)
RIA (radioimmunoassay)
Mass spectrometry
Nuclear magnetic resonance
The most frequently used techniques are: liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) for 'small' molecules and enzyme-linked immunosorbent assay (ELISA) for macromolecules.
Sample preparation and extraction
The bioanalyst deals with complex biological samples containing the analyte alongside a diverse range of chemicals that can have an adverse impact on the accurate and precise quantification of the analyte. As such, a wide range of techniques are applied to extract the analyte from its matrix. These include:
Protein precipitation
Liquid–liquid extraction
Solid phase extraction
Bioanalytical laboratories often deal with large numbers of samples, for example resulting from clinical trials. As such, automated sample preparation methods and liquid-handling robots are commonly employed to increase efficiency and reduce costs.
Bioanalytical organisations
There are several national and international bioanalytical organisations active throughout the world. Often they are part of a bigger organisation, e.g. Bioanalytical Focus Group and Ligand Binding Assay Bioanalytical Focus Group, which are both within the American Association of Pharmaceutical Scientists (AAPS) and FABIAN, a working group of the Analytical Chemistry Section of the Royal Netherlands Chemical Society. The European Bioanalysis Forum (EBF), on the other hand, is independent of any larger society or association.
References
Analytical chemistry
Pharmacokinetics
Toxicology | Bioanalysis | Chemistry,Environmental_science | 912 |
19,749,717 | https://en.wikipedia.org/wiki/Jeep%20problem | The jeep problem, desert crossing problem or exploration problem is a mathematics problem in which a jeep must maximize the distance it can travel into a desert with a given quantity of fuel. The jeep can only carry a fixed and limited amount of fuel, but it can leave fuel and collect fuel at fuel dumps anywhere in the desert.
The problem first appeared in the 9th-century collection Propositiones ad Acuendos Juvenes (Problems to Sharpen the Young), attributed to Alcuin, with the puzzle being about a travelling camel eating grain. The De viribus quantitatis (c. 1500) of Luca Pacioli also discusses the problem. A modern treatment was given by N. J. Fine in 1947.
Problem
There are n units of fuel stored at a fixed base. The jeep can carry at most 1 unit of fuel at any time, and can travel 1 unit of distance on 1 unit of fuel (the jeep's fuel consumption is assumed to be constant). At any point in a trip the jeep may leave any amount of fuel that it is carrying at a fuel dump, or may collect any amount of fuel that was left at a fuel dump on a previous trip, as long as its fuel load never exceeds 1 unit. There are two variants of the problem:
Exploring the desert the jeep must return to the base at the end of every trip.
Crossing the desert the jeep must return to the base at the end of every trip except for the final trip, when the jeep travels as far as it can before running out of fuel.
In either case the objective is to maximize the distance traveled by the jeep on its final trip. Alternatively, the objective may be to find the least amount of fuel required to produce a final trip of a given distance.
Variations
In the classic problem the fuel in the jeep and at fuel dumps is treated as a continuous quantity. More complex variations on the problem have been proposed in which the fuel can only be left or collected in discrete amounts.
Solution
A strategy that maximizes the distance traveled on the final trip for the "exploring the desert" variant is as follows:
The jeep makes n trips. On each trip it starts from base with 1 unit of fuel.
On the first trip the jeep travels a distance of 1/(2n) units and leaves (n − 1)/n units of fuel at a fuel dump. The jeep still has 1/(2n) units of fuel – just enough to return to base.
On each of the subsequent n − 1 trips the jeep collects 1/(2n) units of fuel from this first fuel dump on the way out, so that it leaves the fuel dump carrying 1 unit of fuel. It also collects 1/(2n) units of fuel from this first fuel dump on the way back, which is just enough fuel to return to base.
On the second trip the jeep travels to the first fuel dump and refuels. It then travels a distance of 1/(2n − 2) units and leaves (n − 2)/(n − 1) units of fuel at a second fuel dump. The jeep still has 1/(2n − 2) units of fuel, which is just enough to return to the first fuel dump. Here it collects 1/(2n) units of fuel, which is just enough fuel to return to base.
On each of the subsequent n − 2 trips the jeep collects 1/(2n − 2) units of fuel from this second fuel dump on the way out, so that it leaves the fuel dump carrying 1 unit of fuel. It also collects 1/(2n − 2) units of fuel from the second fuel dump on the way back, which is just enough fuel to return to the first fuel dump.
The jeep continues in this way, so that on trip k it establishes a new kth fuel dump at a distance of 1/(2n − 2k + 2) units from the previous fuel dump and leaves (n − k)/(n − k + 1) units of fuel there. On each of the subsequent n − k trips it collects 1/(2n − 2k + 2) units of fuel from the kth dump on its way out and another 1/(2n − 2k + 2) units of fuel on its way back.
When the jeep starts its final trip, there are n − 1 fuel dumps. The farthest contains 1/2 of a unit of fuel, the next farthest contain 1/3 of a unit of fuel, and so on, and the nearest fuel dump has just 1/n units of fuel left. Together with 1 unit of fuel with which it starts from base, this means that the jeep can travel a total round trip distance of
units on its final trip (the maximum distance traveled into the desert is half of this). It collects half of the remaining fuel at each dump on the way out, which fills its tank. After leaving the farthest fuel dump it travels 1/2 a unit further into the desert and then returns to the farthest fuel dump. It collects the remaining fuel from each fuel dump on the way back, which is just enough to reach the next fuel dump or, in the final step, to return to base.
The distance travelled on the last trip is the nth harmonic number, Hn. As the harmonic numbers are unbounded, it is possible to exceed any given distance on the final trip, as along as sufficient fuel is available at the base. However, the amount of fuel required and the number of fuel dumps both increase exponentially with the distance to be traveled.
The "crossing the desert" variant can be solved with a similar strategy, except that there is now no requirement to collect fuel on the way back on the final trip. So on trip k the jeep establishes a new kth fuel dump at a distance of 1/(2n − 2k + 1) units from the previous fuel dump and leaves (2n − 2k − 1)/(2n − 2k + 1) units of fuel there. On each of the next n − k − 1 trips it collects 1/(2n − 2k + 1) units of fuel from the kth dump on its way out and another 1/(2n − 2k + 1) units of fuel on its way back.
Now when the jeep starts its final trip, there are n − 1 fuel dumps. The farthest contains 1/3 of a unit of fuel, the next farthest contain 1/5 of a unit of fuel, and so on, and the nearest fuel dump has just 1/(2n − 1) units of fuel left. Together with 1 unit of fuel with which it starts from base, this means that the jeep can travel a total distance of
units on its final trip. It collects all of the remaining fuel at each dump on the way out, which fills its tank. After leaving the farthest fuel dump it travels a further distance of 1 unit.
Since
,
it is possible in theory to cross a desert of any size given enough fuel at the base. As before, the amount of fuel required and the number of fuel dumps both increase exponentially with the distance to be traveled.
In summary, the maximum distance reachable by the jeep (with a fuel capacity for 1 unit of distance at any time) in n trips (with n-1 midway fuel dumps and consuming a total of n units of fuel) is
, for exploring the desert where the jeep must return to the base at the end of every trip;
, for crossing the desert where the jeep must return to the base at the end of every trip except for the final trip, when the jeep travels as far as it can before running out of fuel.
Here is the nth harmonic number.
Continuous amount of fuel
The number of fuel units available at the base need not be an integer. In the general case, the maximum distance achievable for the "explore the desert" problem with units of fuel is
with the first fuel dump located at units of distance away from the starting base, the second one at units of distance away from the first fuel dump, the third one at units of distance away from the second fuel dump, and so on. Here is the fractional part of .
The maximum distance achievable for the "cross the desert" problem with units of fuel is
with the first fuel dump located at units of distance away from the starting base, the second one at units of distance away from the first fuel dump, the third one at units of distance away from the second fuel dump, and so on. Here is the fractional part of .
Order independence
The order of the jeep trips is not fixed. For example in the "exploring the desert" version of the problem, the jeep could make round-trips between the base and the first fuel dump, leaving units of fuel at the fuel dump each time and then make an -th trip one-way to the first fuel dump, thus arriving there with a total of units of fuel available. The units are saved for the return trip to base at the very end and the other units of fuel are used to move fuel between the first and second fuel dump, using round-trips and then an -th trip one-way to the second fuel dump. And so on.
Practical applications
The problem can have a practical application in wartime situations, especially with respect to fuel efficiency. In the context of the bombing of Japan in World War II by B-29s, Robert McNamara says in the film The Fog of War that understanding the fuel efficiency issue caused by having to transport the fuel to forward bases was the main reason why the strategy of launching bombing raids from mainland China was abandoned in favor of the island hopping strategy:
(The atomic bombing missions at the end of World War II were flown using B-29 Superfortresses from the Pacific island of Tinian in the Northern Marianas Islands.)
See also
Read Operation Black Buck for better understanding on application of these ideas. In these missions, conducted during the Falklands War, the Royal Air Force used air to air refueling by staging tankers to enable the Vulcan bombers based on Ascension Island to bomb targets in the Falkland Islands.
Harmonic series (mathematics)
Optimization (mathematics)
References
Mathematical optimization
Recreational mathematics | Jeep problem | Mathematics | 2,107 |
14,251,714 | https://en.wikipedia.org/wiki/John%20Barber%20%28engineer%29 | John Barber (1734–1793) was an English coal viewer and inventor. He was born in Nottinghamshire, but moved to Warwickshire in the 1760s to manage collieries in the Nuneaton area. For a time he lived in Camp Hill House, between Hartshill and Nuneaton, and later lived in Attleborough. The same John Barber is thought to be the inventor named in several patents granted between 1766 and 1792. The most remarkable of these patents was for a gas turbine. Although nothing practical came out of this patent, Barber is recognised as the first person to describe the working principle of a constant pressure gas turbine.
Barber's gas turbine
In 1791 Barber took out a patent (UK patent no. 1833 – Obtaining and Applying Motive Power, & c. A Method of Rising Inflammable Air for the Purposes of Procuring Motion, and Facilitating Metallurgical Operations) which is recognised as containing the key features of a gas turbine. Barber's design included a chain-driven, reciprocating gas compressor, a combustion chamber, and a turbine.
Barber's turbine was designed to burn producer gas obtained from wood, coal, oil, or other substances, heated in a retort or producer, from where the gases were conveyed into a receiver and cooled. Air and gas were then to be compressed in different cylinders and discharged into an "exploder" (combustion chamber) where they were ignited, the mixture of hot gas then being played against the vanes of a paddle wheel. Water was to be injected into the explosive mixture to cool the mouth of the chamber and, by producing steam, to increase the volume of the charge.
The patent proposed various uses for the gas turbine including propulsion of ships, barges and boats by reaction, mechanical operations (grinding, rolling, forging etc.) and injection of the exhaust stream into furnaces for smelting ores.
Legacy
Given the technologies available to Barber, it is unlikely that a gas turbine could have been built that would have been able to create sufficient power to both compress the air and the gas and produce useful work. It wasn't until 1939, some 148 years after Barber's initial patent, that the first constant pressure gas turbine entered service in Neuchâtel, Switzerland.
In the same year that Brown, Boveri & Cie commissioned the Neuchâtel gas turbine the company published an article on the history of gas turbines which acknowledged John Barber's patent. John Barber is widely accepted as being the first person to patent a gas turbine.
See also
History of the internal combustion engine
References
Further reading
H. S. Torrens, 'Barber, John (1734–1793)’, Oxford Dictionary of National Biography, Oxford University Press, 2004 Retrieved 29 July 2016
English engineers
British coal miners
People from Nuneaton
1734 births
Gas turbines
English inventors | John Barber (engineer) | Technology | 579 |
295,183 | https://en.wikipedia.org/wiki/Galilean%20transformation | In physics, a Galilean transformation is used to transform between the coordinates of two reference frames which differ only by constant relative motion within the constructs of Newtonian physics. These transformations together with spatial rotations and translations in space and time form the inhomogeneous Galilean group (assumed throughout below). Without the translations in space and time the group is the homogeneous Galilean group. The Galilean group is the group of motions of Galilean relativity acting on the four dimensions of space and time, forming the Galilean geometry. This is the passive transformation point of view. In special relativity the homogeneous and inhomogeneous Galilean transformations are, respectively, replaced by the Lorentz transformations and Poincaré transformations; conversely, the group contraction in the classical limit of Poincaré transformations yields Galilean transformations.
The equations below are only physically valid in a Newtonian framework, and not applicable to coordinate systems moving relative to each other at speeds approaching the speed of light.
Galileo formulated these concepts in his description of uniform motion.
The topic was motivated by his description of the motion of a ball rolling down a ramp, by which he measured the numerical value for the acceleration of gravity near the surface of the Earth.
Translation
Although the transformations are named for Galileo, it is the absolute time and space as conceived by Isaac Newton that provides their domain of definition. In essence, the Galilean transformations embody the intuitive notion of addition and subtraction of velocities as vectors.
The notation below describes the relationship under the Galilean transformation between the coordinates and of a single arbitrary event, as measured in two coordinate systems and , in uniform relative motion (velocity ) in their common and directions, with their spatial origins coinciding at time :
Note that the last equation holds for all Galilean transformations up to addition of a constant, and expresses the assumption of a universal time independent of the relative motion of different observers.
In the language of linear algebra, this transformation is considered a shear mapping, and is described with a matrix acting on a vector. With motion parallel to the x-axis, the transformation acts on only two components:
Though matrix representations are not strictly necessary for Galilean transformation, they provide the means for direct comparison to transformation methods in special relativity.
Galilean transformations
The Galilean symmetries can be uniquely written as the composition of a rotation, a translation and a uniform motion of spacetime. Let represent a point in three-dimensional space, and a point in one-dimensional time. A general point in spacetime is given by an ordered pair .
A uniform motion, with velocity , is given by
where . A translation is given by
where and . A rotation is given by
where is an orthogonal transformation.
As a Lie group, the group of Galilean transformations has dimension 10.
Galilean group
Two Galilean transformations and compose to form a third Galilean transformation,
.
The set of all Galilean transformations forms a group with composition as the group operation.
The group is sometimes represented as a matrix group with spacetime events as vectors where is real and is a position in space.
The action is given by
where is real and and is a rotation matrix.
The composition of transformations is then accomplished through matrix multiplication. Care must be taken in the discussion whether one restricts oneself to the connected component group of the orthogonal transformations.
has named subgroups. The identity component is denoted .
Let represent the transformation matrix with parameters :
anisotropic transformations.
isochronous transformations.
spatial Euclidean transformations.
uniformly special transformations / homogeneous transformations, isomorphic to Euclidean transformations.
shifts of origin / translation in Newtonian spacetime.
rotations (of reference frame) (see SO(3)), a compact group.
uniform frame motions / boosts.
The parameters span ten dimensions. Since the transformations depend continuously on , is a continuous group, also called a topological group.
The structure of can be understood by reconstruction from subgroups. The semidirect product combination () of groups is required.
( is a normal subgroup)
Origin in group contraction
The Lie algebra of the Galilean group is spanned by and (an antisymmetric tensor), subject to commutation relations, where
is the generator of time translations (Hamiltonian), is the generator of translations (momentum operator), is the generator of rotationless Galilean transformations (Galileian boosts), and stands for a generator of rotations (angular momentum operator).
This Lie Algebra is seen to be a special classical limit of the algebra of the Poincaré group, in the limit . Technically, the Galilean group is a celebrated group contraction of the Poincaré group (which, in turn, is a group contraction of the de Sitter group ).
Formally, renaming the generators of momentum and boost of the latter as in
,
where is the speed of light (or any unbounded function thereof), the commutation relations (structure constants) in the limit take on the relations of the former.
Generators of time translations and rotations are identified. Also note the group invariants and .
In matrix form, for , one may consider the regular representation (embedded in , from which it could be derived by a single group contraction, bypassing the Poincaré group),
The infinitesimal group element is then
Central extension of the Galilean group
One may consider a central extension of the Lie algebra of the Galilean group, spanned by and an operator M:
The so-called Bargmann algebra is obtained by imposing , such that lies in the center, i.e. commutes with all other operators.
In full, this algebra is given as
and finally
where the new parameter shows up.
This extension and projective representations that this enables is determined by its group cohomology.
See also
Galilean invariance
Representation theory of the Galilean group
Galilei-covariant tensor formulation
Poincaré group
Lorentz group
Lagrangian and Eulerian coordinates
Notes
References
, Chapter 5, p. 83
, Chapter 38 §38.2, p. 1046,1047
, Chapter 2 §2.6, p. 42
, Chapter 9 §9.1, p. 261
Theoretical physics
Time in physics | Galilean transformation | Physics | 1,286 |
2,640,438 | https://en.wikipedia.org/wiki/Professional%20submissive | A professional submissive is a person who performs the submissive role in BDSM activities in exchange for money. Most professional submissives do not have sex with their clients.
Professional submissives are rarer than professional dominants.
References
External links
BDSM terminology
Sex workers | Professional submissive | Biology | 59 |
55,227,015 | https://en.wikipedia.org/wiki/Pithomyces%20chartarum | Pithomyces chartarum is a fungus predominantly found in subtropical countries and other localities with warmer climates. However, it occurs throughout the world including the United Kingdom, Europe and Netherlands. Pithomyces chartarum produces a mycotoxin called sporidesmin when it grows on plants, particularly grasses. Presence of the toxin in forage grasses causes facial eczema in sheep, and is especially problematic in areas such as New Zealand where sheep are intensively raised. Other health effect of P. chartarum are not well understood.
History and taxonomy
This species was first discovered by Miles Berkeley and Moses Ashley Curtis as Sporidesmium chartarum in 1874. It was independently named Sporidesmium bakeri by German mycologists Hans and Paul Sydow in 1914. Canadian mycologist Stanley Hughes examined specimens of both taxa in 1958 and concluded that they represented the same taxon which he contemplated assigning them to the genus Scheleobrachea. Several years later, the British mycologist Martin Ellis described the fungus in the genus Pithomyces as P. chartarum. It has been suggested that P. chartarum may be indigenous to New Zealand.
Growth and morphology
Pithomyces chartarum produces spores that are multicellular and darkly pigmented, although they are produced sparsely. The spores can be barrel-shaped, ellipsoidal or club-shaped. Pithomyces chartarum has three vegetative hyphal types: sparsely septate, densely septate, and densely septate with surface spines. The colonies are fast growing and their morphology depends on temperature. When the temperature is below , the sparsely septate morphology predominates in contrast to the densely septate for that is stimulated by temperatures of . The spores that are germinating produce hyaline superficial hyphae which can easily penetrate plant cell walls. The conidiophores bear simple conidia, they are short, thin walled and usually nonseptate. The conidia are considered aleurioconidia because they arise singly at the apex of each conidiophore. Conidia may also form in clusters on a network of conidiogenous branches. Mature conidia typically have three transverse septa and up to two longitudinal septa.
Physiology
The production of conidia and vegetative hyphae are good at . Conidia require free water to germinate and do not germinate at water potentials below −140 bars. The production of conidia is stimulated in vitro by exposure to near UV-light. Warm ground temperatures and high humidity cause rapid growth but lower temperatures result in higher sporidesmin content of conidia. Pithomyces chartarum produces sporidesmin but also has been seen to produce cyclodepsipeptides and sporidemolides.
Habitat and ecology
Pithomyces chartarum is more likely to be found in tropical locations but its range might be expanding. It can be found in pastures growing on debris and on damaged potato leaves, on dead leaves and stem of plants and occasionally in indoor environments on paper, ceiling tiles and may be present in carpet and mattress dust. It is thought to be especially frequent on fodder grasses. Pithomyces chartarum foliar infections can be clearly observed because they result in the formation of necrotic spots; however, recent studies have suggested that plant infections may be asymptomatic under certain circumstances. Growth of the fungus is inhibited in vitro by Bacillus subtilis and cochliodinol.
Disease
Pithomyces chartarum is known to cause facial eczema in sheep and cattle, prevalent in New Zealand and occasionally in Australia. It is more common in sheep and deer, and goats seem to be less affected. Due to the growth required for the spores, we normally see cases occur after warm rains in fall or in summer. Symptoms of animal illness are usually apparent 10–14 days after ingestion. Animal disease caused by this fungus can be controlled in farm animals by avoiding short grazing, feeding cattle zinc or by using benzimidazole fungicides on pastures. The effects on human health are not well understood but it is thought that P. chartarum could also be involved in glue blotch disease of rice.
References
Pleosporales
Fungus species | Pithomyces chartarum | Biology | 899 |
22,050,856 | https://en.wikipedia.org/wiki/Personal%20jurisdiction%20over%20international%20defendants%20in%20the%20United%20States | Questions over personal jurisdiction over foreign defendants in the United States arise when foreign nationals commit crimes against Americans, or when a person from or in a different country is sued in U.S. courts, or when events took place in another country. Such cases arise when crimes are committed on the high seas or on international flights, when crimes are alleged to be committed by or against Americans in foreign countries (such as under the Foreign Corrupt Practices Act), or when crimes are committed by foreigners against Americans. The Internet also allows computer crime to cross international boundaries.
Mechanism in public international law for exercising jurisdiction over an international defendant
There are several mechanisms in public international law whereby the courts of one country (the domestic court) can exercise jurisdiction over a citizen, corporation, or organization of another country (the foreign defendant) to try crimes or civil matters that have affected citizens or businesses within the domestic jurisdiction. Many of these jurisdictional "hooks" can even reach conduct that affected the domestic citizen when the citizen was beyond his or her domestic borders. There are five such doctrines:
The territorial principle is the most important and widely used. It is the idea that a state may claim jurisdiction over persons and events inside its own territory. So, foreign nationals committing crimes in the U.S. are subject to U.S. courts and U.S. laws.
The nationality principle holds that the government of a citizen can obtain jurisdiction over its citizen even when that citizen is abroad. For example, U.S. citizens are still required to pay federal taxes to the U.S. government when abroad and may be prosecuted for a failure to do so.
The passive personality principle is an interesting offshoot of the nationality principle. It looks to the nationality of the victim to determine jurisdiction, holding that a state may assert jurisdiction over persons and events outside a state's territory on the basis that its citizen has been harmed. In the case of United States v. Roberts, 1 F.Supp. 2d 601 (E.D. La. 1998), which had an unusual set of facts, the victim of a crime of sexual abuse of a minor (who was a U.S. citizen) had a case tried against her aggressor who was a citizen of the Caribbean island of Saint Vincent and the Grenadines. The crime took place on international waters on board a ship registered in Liberia and owned by a company incorporated in the Republic of Panama. None of the regular methods of jurisdiction, forum non conveniens, or comity would have worked. Id. The defendant was indicted by a federal grand jury in the Eastern District of Louisiana and the defendant's motion to dismiss for lack of personal jurisdiction was denied by the federal district court, which found jurisdiction under the passive personality principle.
The protective principle is one of national security and it holds that a state may have jurisdiction over a defendant accused of acts in pursuance of overthrowing the host state's government. See United States v. Yousef, 327 F3d 56 (2d Cir. 2003).
The universality principle (principle of universal jurisdiction) is closely aligned with the international law doctrine of peremptory norms (jus cogens). The principle holds that all states have jurisdiction over crimes that are universally recognized to be a crime against humanity. These have historically included piracy, slave-trading, torture, genocide, and perhaps terrorism.
In the United States, the federal courts have recognized an important mechanism for acquiring jurisdiction over foreign defendants known as the effects doctrine. The effects doctrine is an offshoot of the territorial principle. Briefly, the effects doctrine says that if the effects of extraterritorial behavior or crimes adversely affect commerce or harm citizens within the United States, then jurisdiction in a U.S. court is permissible. The first case to establish the effects doctrine was United States v. Alcoa, 148 F.2d 416 (2d Cir. 1945) (Learned Hand, J.).
The ALCOA case brought charges against a foreign consortium of aluminum traders and producers who had affected the price of raw aluminum and goods manufactured from aluminum in the United States through unfair trade practices of price fixing in violation of section 1 of the Sherman Antitrust Act ("every contract, combination ... or conspiracy, in restraint of trade or commerce among the several States, or with foreign nations, is declared to be illegal").
The effects doctrine has also been incorporated into § 402 of the Restatement of Foreign Relations Law of the United States, Third: "a state has jurisdiction to prescribe law with respect to ... (c) conduct outside its territory that has or is intended to have substantial effect within its territory."
Raju case
In one case, the decision to allow jurisdiction in a U.S. court over claims of copyright infringement and cybersquatting was premised on an effects doctrine theory of jurisdiction. Graduate Management Admission Council v. Raju, 241 F.Supp.2d 589 (E.D. Va., 2003). The defendant in Raju was a citizen of India who sold "official" past Graduate Record Examinations (GREs) to U.S. customers that were of dubious origin and in violation of the plaintiff, copyright-holder Graduate Management Admission Council (GMAC). These exams were advertised and sold over the Internet.
The defendant never made an appearance on U.S. territory depriving the plaintiffs of one easy avenue of obtaining in personam jurisdiction over the defendant – the simple act of being able to serve process on the defendant while the defendant is visiting and within the territory of the United States (this would be the traditional territorial principle of jurisdiction at work, to use terms of international law). The defendant was not a citizen of a particular state. The court described the jurisdiction it exercised over Raju's conduct of selling illegal copies of the exams to potential purchasers in several states within the territory of the U.S. as "targeting" the U.S. market for U.S. purchasers. Under these circumstances, the court found that personal jurisdiction was proper under a theory of national jurisdiction: the defendant had targeted the U.S. at large from outside of the territory and intended to avail himself of the opportunity of selling test answers to a U.S. graduate school entrance test to his most likely customers: Americans.
A judgment was issued against the defendant Raju who defaulted by never making an appearance to the district court where he was being sued.
Additional cases
In a procedurally complicated case, Yahoo! Inc. v. La Ligue Contre Le Racisme et l'Antisemitisme (LICRA), the 9th Circuit Court of Appeals held that it had personal jurisdiction over two French organizations who sued Yahoo! in a French court. The court found that all of the following acts, in combination, were sufficient contacts to create personal jurisdiction over the French organizations: sending letters to Yahoo!, suing Yahoo! and serving Yahoo! in California, and the suit resulting in orders that Yahoo!'s officers in California comply with French law.
References
International law
Computer law
Jurisdiction
Law of the United States | Personal jurisdiction over international defendants in the United States | Technology | 1,447 |
44,559,494 | https://en.wikipedia.org/wiki/Tylopilus%20alkalixanthus | Tylopilus alkalixanthus is a bolete fungus in the family Boletaceae. Found in Costa Rica and Japan, it was described as new to science in 2002 by Anja Amtoft and Roy Halling.
References
External links
alkalixanthus
Fungi described in 2002
Fungi of Asia
Fungi of Central America
Fungus species
Taxa named by Roy Halling | Tylopilus alkalixanthus | Biology | 77 |
14,818,515 | https://en.wikipedia.org/wiki/PRRX1 | Paired related homeobox 1 is a protein that in humans is encoded by the PRRX1 gene.
Function
The DNA-associated protein encoded by this gene is a member of the paired family of homeobox proteins localized to the nucleus. The protein functions as a transcription coactivator, enhancing the DNA-binding activity of serum response factor, a protein required for the induction of genes by growth and differentiation factors. The protein regulates muscle creatine kinase, indicating a role in the establishment of diverse mesodermal muscle types. Alternative splicing yields two isoforms that differ in abundance and expression patterns.
Role in mesenchymal stem cell differentiation
Prrx1 expression is restricted to the mesoderm during embryonic development, and both Prrx1 and Prrx2 are expressed in mesenchymal tissues in adult mice. Mice that lack both Prrx1 and Prrx2 have profound defects in mesenchymal cell differentiation in the craniofacial region. Several recent studies demonstrate that PRRX1 can regulate differentiation of mesenchymal precursors. For example, PRRX1 inhibits adipogenesis by activating transforming growth factor-beta (TGF-beta) signaling, and also acts downstream of tumor necrosis factor-alpha to inhibit osteoblast differentiation.
References
Further reading
External links
Transcription factors | PRRX1 | Chemistry,Biology | 284 |
23,484,704 | https://en.wikipedia.org/wiki/Iodocholesterol | Iodocholesterol, or 19-iodocholesterol, also as iodocholesterol (131I) (INN) and NP-59, is a derivative of cholesterol with an iodine atom in the C19 position and a radiopharmaceutical. When the iodine atom is a radioactive isotope (iodine-125 or iodine-131), it is used as an adrenal cortex radiotracer in the diagnosis of patients suspected of having Cushing's syndrome, hyperaldosteronism, pheochromocytoma, and adrenal remnants following total adrenalectomy.
References
Cholestanes
Organoiodides
Radiopharmaceuticals | Iodocholesterol | Chemistry | 152 |
24,679,621 | https://en.wikipedia.org/wiki/Cocaine%20%28data%20page%29 | This page provides supplementary chemical data on Cocaine in free base form. More commonly available "powder cocaine" is a hydrochloride salt whose properties will differ.
Material Safety Data Sheet
The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source such as SIRI, and follow its directions.
Structure and properties
Thermodynamic properties
Spectral data
External links
Nuclear magnetic resonance and molecular orbital study of some cocaine analogues, includes superposition and overlay of cocaine, cocaine derivatives, and their minimum energy values.
Conformational changes in dopamine transporter intracellular regions upon cocaine binding and dopamine translocation, thorough-going elucidation of exact mechanism and mode of action specific to cocaine at the dopamine transporter.
Genome Wide Analysis of Chromatin Regulation by Cocaine Reveals a Novel Role for Sirtuins
References
Chemical data pages
Chemical data pages cleanup | Cocaine (data page) | Chemistry | 203 |
1,309,209 | https://en.wikipedia.org/wiki/Lambda%20Scorpii | Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named Shaula; Lambda Scorpii is its Bayer designation, which is Latinised from λ Scorpii and abbreviated Lambda Sco or λ Sco. With an apparent visual magnitude of 1.62, it is one of the brightest stars in the night sky.
Nomenclature
λ Scorpii (Latinised to Lambda Scorpii) is the star system's Bayer designation.
It bore the traditional name Shaula, which comes from the Arabic الشولاء al-šawlā´ meaning 'the raised [tail]', as it is found in the tail of Scorpius, the scorpion. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Shaula for the star λ Scorpii Aa.
In Indian Astronomy it is called MulA Nakshathram. Mūla ("root") (Devanagari मूल/मूळ) (Tamil: மூலம்) is the 19th nakshatra or "lunar mansion" in Vedic astrology. The symbol of Mula is a bunch of roots tied together (reticulated roots) or an 'elephant goad' (ankusha).
In Chinese, (), meaning Tail, refers to an asterism consisting of λ Scorpii, ε Scorpii, ζ1 Scorpii, ζ2 Scorpii, η Scorpii, θ Scorpii, ι1 Scorpii, ι2 Scorpii, κ Scorpii, μ1 Scorpii, and υ Scorpii. Consequently, the Chinese name for λ Scorpii itself is (), "the Eighth Star of Tail".
Together with υ Scorpii (Lesath), Shaula is listed in the Babylonian compendium MUL.APIN as dSharur4 u dShargaz, meaning "Sharur and Shargaz".
In Coptic, they were called Minamref.
The indigenous Boorong people of northwestern Victoria (Australia) named it (together with Upsilon Scorpii) Karik Karik, "the Falcons".
Properties
Lambda Scorpii is located some 570 light-years away from the Sun.
Spectroscopic and interferometric observations have shown that it is actually a triple star system consisting of two B-type stars and a pre-main-sequence star. The primary star is a Beta Cephei variable star with rapid brightness changes of about a hundredth of a magnitude. The pre-main-sequence star has an orbital period of 6 days and the B companion has a period of 1053 days. The three stars lie in the same orbital plane, strongly suggesting that they were formed at the same time. The masses of the primary, pre-main-sequence star and the B companion are 14.5, 2.0 and 10.6 solar masses, respectively. The age of the system is estimated to be in the range 10–13 million years.
A 15th-magnitude star has a separation of 42 arcseconds, whereas a 12th-magnitude star is 95 arcseconds away. It is not known whether or not these components are physically associated with Lambda Scorpii. If they both were, the first would have a projected linear separation of approximately 7,500 astronomical units (AU) and the second approximately 17,000 AU (0.27 light-years) away. Gaia Data Release 3 reports that the fainter of these two stars is a little larger and brighter than the sun and about 420 light years away, while the brighter star is a luminous background object.
In culture
Shaula appears on the flag of Brazil, symbolizing the state of Rio Grande do Norte.
USS Shaula (AK-118) was a U.S. Navy Crater-class cargo ship named after the star.
References
B-type subgiants
Beta Cephei variables
White dwarfs
5
Scorpius
Scorpii, Lambda
6527
Durchmusterung objects
Scorpii, 35
158926
085927
Shaula | Lambda Scorpii | Astronomy | 918 |
20,163,518 | https://en.wikipedia.org/wiki/Process%20flowsheeting | Process flowsheeting is the use of computer aids to perform steady-state heat and mass balancing, sizing and costing calculations for a chemical process. It is an essential and core component of process design.
The process design effort may be split into three basic steps
Synthesis
Analysis and
Optimization.
Synthesis
Synthesis is the step where the structure of the flowsheet is chosen. It is also in this step that one initializes values for variables which one is free to set.
Analysis
Analysis is usually made up of three steps
Solving heat and material balances
Sizing and costing the equipment and
Evaluating the economic worth, safety, operability etc. of the chosen flow sheet
Optimization
Optimization involves both structural optimization of the flow sheet itself as well as optimization of parameters in a given flowsheet. In the former one may alter the equipment used and/or its connections with other equipment. In the latter one can change the values of parameters such as temperature and pressure. Parameter Optimization is a more advanced stage of theory than process flowsheet optimization.
Plant design project
The first step in the sequence leading to the construction of a process plant and its use in the manufacture of a product is the conception of a process. The concept is embodied in the form of a "flow sheet". Process design then proceeds on the basis of the flow sheet chosen. Physical property data are the other component needed for process design apart from a flow sheet. The result of process design is a process flow diagram, PFD. Detailed engineering for the project and vessel specifications then begin. Process flowsheeting ends at the point of generation of a suitable PFD.
General purpose flowsheeting programs became usable and reliable around 1965-1970.
See also
List of chemical process simulators
CAPE-OPEN Interface Standard
Process simulation
References
Westerberg A. W., Hutchinson H. P., Motard R. L., and Winter P., (1979), "Process Flowsheeting", Cambridge Universities Press,
Veverka V. V., and Madron, F. (1997), "Material and Energy balancing in the Process Industries", Elsevier,
Babu, B. V.(2004), "Process Plant Simulation", Oxford Universities Press, ISBN
External links
Process flowsheet development using process simulation software
Chemical process engineering
Process engineering | Process flowsheeting | Chemistry,Engineering | 469 |
370,398 | https://en.wikipedia.org/wiki/Municipal%20charter | A city charter or town charter (generically, municipal charter) is a legal document (charter) establishing a municipality such as a city or town. The concept developed in Europe during the Middle Ages.
Traditionally, the granting of a charter gave a settlement and its inhabitants the right to town privileges under the feudal system. Townspeople who lived in chartered towns were burghers, as opposed to serfs who lived in villages. Towns were often "free", in the sense that they were directly protected by the king or emperor, and were not part of a feudal fief.
Today, the process for granting is determined by the type of government of the state in question. In monarchies, charters are still often a royal charter given by the Crown or the authorities acting on behalf of the Crown. In federations, the granting of charters may be within the jurisdiction of the lower level of government, such as a province.
Canada
In Canada, charters are granted by provincial authorities.
Germany
Philippines
Since the beginning of American colonial rule, Philippines cities were formally established through laws enacted by the various national legislatures in the country. The Philippine Commission gave the city of Manila its charter in 1901, while the city of Baguio was established by the Philippine Assembly which was composed by elected members instead of appointed ones. During the Commonwealth era, the National Assembly established an additional ten cities. Since achieving independence from the United States in 1946 the Philippine Congress has established 149 more cities (), the majority of which required the holding of a plebiscite within the proposed city's jurisdiction to ratify the city's charter.
Sweden
In Sweden until 1951, cities were established by royal charter.
United Kingdom
In the United Kingdom, cities are established by royal charter.
United States
In the United States, such charters are established either directly by a state legislature by means of local legislation, or indirectly under a general municipal corporation law, usually after the proposed charter has passed a referendum vote of the affected population.
A municipal charter is the basic document that defines the organization, powers, functions and essential procedures of the city government. The charter is, therefore, the most important legal document of any city. Municipalities without charters, in states where such exist, are known as general-law municipalities or cities.
See also
Home rule
References
Further reading
Winfield, P.H., The charter of San Francisco (The fortnightly review Vol. 157-58:2 (1945), p. 69-75)
Roger L. Kemp, "Model Government Charters: A City, County, Regional, State, and Federal Handbook" (2007), McFarland and Co., Inc., Jefferson, NC, and London, ENG. ()
Roger L. Kemp "Documents of American Democracy: A Collection of Essential Works", McFarland and Co., Inc., Jefferson, NC, and London, Eng. ()
External links
Feudalism
Free imperial cities
Local government in the United Kingdom
Local government in the United States
Medieval law
Urban planning | Municipal charter | Engineering | 607 |
5,314,955 | https://en.wikipedia.org/wiki/Body%20capacitance | Body capacitance is the physical property of a human body to act as a capacitor. Like any other electrically conductive object, a human body can store electric charge if insulated. The actual amount of capacitance varies with the surroundings; it would be low when standing on top of a pole with nothing nearby, but high when leaning against an insulated, but grounded large metal surface, such as a household refrigerator, or a metal wall in a factory.
When a human's body capacitance is charged to a high voltage by friction or other means, it can produce undesirable effects when abruptly discharged as a spark. The influence of body capacitance on a tuned circuit may also change its resonant frequency, which would affect the performance of radio receivers. A capacitive sensing circuit that detects a change in body capacitance from a human finger can be used for a touchscreen or a touch switch, allowing control of devices without depressing mechanical switches.
Properties
Friction with some fabrics can act as an electrostatic generator that can charge a human body to about . Some electronic devices can be damaged by voltages of the order of . The breakdown voltages of metal oxide semiconductors without protection diodes may be even lower. Electronics factories are careful to prevent people from becoming charged. A branch of the electronics industry deals with preventing static charge build-up and protecting products against electrostatic discharge.
Notably, a combination of footwear with some sole materials, low humidity, and a dry carpet can cause footsteps to charge a person's body capacitance to as much as a few tens of kilovolts with respect to the earth. The human and surroundings then constitute a highly charged capacitor. A close approach to any conductive object connected to earth (ground) can create a shock, even a visible spark.
Capacitance of a human body in normal surroundings is typically in the tens to low hundreds of picofarads, which is small by typical electronic standards. The human-body model defined by the Electrostatic Discharge Association (ESDA) is a capacitor in series with a resistor. While humans are much larger than typical electronic components, they are also mostly separated by significant distance from other conductive objects. But close contact with another conducting body may cause an abrupt discharge of the stored energy as a spark. Although the occasional static shock can be startling and even unpleasant, the amount of stored energy is relatively low, and won't harm a healthy person. But it can result in momentary pain and a startle response that may cause further accidents. The spark may damage sensitive materials or electronic devices and in exceptional cases may ignite flammable gas or vapor resulting in a fire.
Touch sensors
Body capacitance can be used to operate touch switches (e.g. for elevators or faucets). They respond to close approach of a part of a human body, usually a fingertip. They don't require applying any force to their surfaces. Rather, the capacitance between electrodes at the device's surface and the fingertip is sensed.
Tuned circuits
Radio receivers rely on tuned circuits to isolate the frequency of a particular desired signal. Body capacitance was a significant nuisance when tuning the earliest radios; touching the tuning knob controlling the tuner's variable capacitor would couple the body capacitance into the tuning circuit, slightly changing its resonant frequency. Design of such circuits intended to be adjusted by a user must prevent interaction of the user's body capacitance with the resonant circuit, so that the resonant frequency is not affected. For example, a metal shield may be placed behind a tuning knob so that the presence of an operator's hand does not affect the tuning.
Body capacitance is exploited in the theremin to shift the frequency of the musical instrument's internal oscillators (one oscillator controls pitch and the other controls loudness).
See also
Self capacitance
Triboelectric series
Triboelectric effect
Touch-sensitive lamp
Test light: certain voltage tester probes rely on body capacitance
References
External links
Downloadable electrostatic BEM modules in MATLAB for self-capacitance of a human body and relevant human body meshes
Energy storage
Capacitors
Biotechnology | Body capacitance | Physics,Biology | 897 |
58,507,832 | https://en.wikipedia.org/wiki/Aspergillus%20umbrosus | Aspergillus umbrosus (also named A. glaucus) is a species of fungus in the genus Aspergillus. It is from the Aspergillus section. The species was first described in 1912. It has been reported to produce asperflavin, auroglaucin, bisanthrons, dihydroauroglaucin, echinulins, emodin, epiheveadrides, erythroglaucin, flavoglaucin, isoechinulins, neoechinulins, physcion, questin, questinol, tetracyclic, and tetrahydroauroglaucin.
References
umbrosus
Fungi described in 1912
Fungus species | Aspergillus umbrosus | Biology | 158 |
52,223,658 | https://en.wikipedia.org/wiki/Maskin%20monotonicity | Maskin monotonicity is a desired property of voting systems suggested by Eric Maskin.
Each voter reports his entire preference relation over the set of alternatives. The set of reports is called a preference profile. A social choice rule maps the preference profile to the selected alternative.
For a preference profile with a chosen alternative , there is another preference profile such that the position of relative to each of the other alternatives either improves or stays the same as in . With Maskin monotonicity, should still be chosen at .
Maskin monotonicity is a necessary condition for implementability in Nash equilibrium. Moreover, any social choice rule that satisfies Maskin monotonicity and another property called "no veto power" can be implemented in Nash equilibrium form if there are three or more voters.
See also
Monotonicity (mechanism design)
The monotonicity criterion in voting systems
References
Mechanism design
Voting | Maskin monotonicity | Mathematics | 180 |
27,447,573 | https://en.wikipedia.org/wiki/Dependability%20state%20model | A dependability state diagram is a method for modelling a system as a Markov chain. It is used in reliability engineering for availability and reliability analysis.
It consists of creating a finite-state machine which represent the different
states a system may be in. Transitions between states happen as a result of events from underlying Poisson processes with different intensities.
Example
A redundant computer system consist of identical two-compute nodes, which each fail with an intensity of . When failed, they are repaired one at the time by a single repairman with negative exponential distributed repair times with expectation .
state 0: 0 failed units, normal state of the system.
state 1: 1 failed unit, system operational.
state 2: 2 failed units. system not operational.
Intensities from state 0 and state 1 are , since each compute node has a failure intensity of . Intensity from state 1 to state 2 is .
Transitions from state 2 to state 1 and state 1 to state 0 represent the repairs of the compute nodes and have the intensity , since only a single unit is repaired at the time.
Availability
The asymptotic availability, i.e. availability over a long period, of the system is equal to the probability that the model is in state 1 or state 2.
This is calculated by making a set of linear equations of the state transition and solving the linear system.
The matrix is constructed with a row for each state. In a row, the intensity into the state is set in the column with the same index, with a negative term.
The identities cells balance the sum of their column to 0:
In addition the equality clause must be taken into account:
By solving this equation, the probability of being in state 1 or state 2 can be found, which
is equal to the long-term availability of the service.
Reliability
The reliability of the system is found by making the failure states absorbing, i.e. removing all outgoing state transitions.
For this system the function is:
Criticism
Finite state models of systems are subject to state explosion. To create
a realistic model of a system one ends up with a model with so many states that it is infeasible to solve or draw the model.
References
Reliability engineering
Markov models
Graphical models | Dependability state model | Engineering | 448 |
738,921 | https://en.wikipedia.org/wiki/Interior%20Design%20%28magazine%29 | Interior Design is an American interior design magazine, which has been in circulation since 1932.
History and profile
Interior Design was founded by Harry V. Anderson in Manhattan in 1932. He was also the publisher and editor of the magazine, which temporarily ceased publication during World War II. Following the war Anderson and John Hay Whitney of Whitney Communications Company relaunched the magazine. In 1959 the company became the sole owner of Interior Design. Harry V. Anderson served as the editor and publisher until 1969.
The other editors have included Donald D. Macmillan; Sherman R. Emery, from 1960 to 1983; and Stanley Abercrombie. The current editor is Cindy Allen. In 1984 Cahners Publishing, later Reed Business Information, bought the magazine from Whitney Communications Company. Sandow Media acquired the magazine in March 2010. The interior design magazine is headquartered in New York City.
See also
List of United States magazines
References
Macmillan, Donald D., Sherman R. Emery, and Stanley Abercrombie. "About Us." Interior Design. Shadow, 2014. Web. 30 Nov. 2015
External links
, the magazine's official website
Visual arts magazines published in the United States
Monthly magazines published in the United States
Arts and crafts magazines
Design magazines
English-language magazines
Interior design
Magazines established in 1932
Magazines published in New York City | Interior Design (magazine) | Engineering | 262 |
27,701,374 | https://en.wikipedia.org/wiki/Big%20M%20method | In operations research, the Big M method is a method of solving linear programming problems using the simplex algorithm. The Big M method extends the simplex algorithm to problems that contain "greater-than" constraints. It does so by associating the constraints with large negative constants which would not be part of any optimal solution, if it exists.
Algorithm
The simplex algorithm is the original and still one of the most widely used methods for solving linear maximization problems. However, to apply it, the origin (all variables equal to 0) must be a feasible point. This condition is satisfied only when all the constraints (except non-negativity) are less-than constraints and with positive constant on the right-hand side. The Big M method introduces surplus and artificial variables to convert all inequalities into that form. The "Big M" refers to a large number associated with the artificial variables, represented by the letter M.
The steps in the algorithm are as follows:
Multiply the inequality constraints to ensure that the right hand side is positive.
If the problem is of minimization, transform to maximization by multiplying the objective by −1.
For any greater-than constraints, introduce surplus si and artificial variables ai (as shown below).
Choose a large positive Value M and introduce a term in the objective of the form −M multiplying the artificial variables.
For less-than or equal constraints, introduce slack variables si so that all constraints are equalities.
Solve the problem using the usual simplex method.
For example, x + y ≤ 100 becomes x + y + s1 = 100, whilst x + y ≥ 100 becomes x + y − s1 + a1 = 100. The artificial variables must be shown to be 0. The function to be maximised is rewritten to include the sum of all the artificial variables. Then row reductions are applied to gain a final solution.
The value of M must be chosen sufficiently large so that the artificial variable would not be part of any feasible solution.
For a sufficiently large M, the optimal solution contains any artificial variables in the basis (i.e. positive values) if and only if the problem is not feasible.
However, the a-priori selection of an appropriate value for M is not trivial. A way to overcome the need to specify the value of M is described in.
Other usage
When used in the objective function, the Big M method sometimes refers to formulations of linear optimization problems in which violations of a constraint or set of constraints are associated with a large positive penalty constant, M.
When used in the constraints themselves, one of the many uses of Big M, for example, refers to ensuring equality of variables only when a certain binary variable takes on one value, but to leave the variables "open" if the binary variable takes on its opposite value. One instance of this is as follows: for a sufficiently large M and z binary variable (0 or 1), the constraints
ensure that when then . Otherwise, when , then , indicating that the variables x and y can have any values so long as the absolute value of their difference is bounded by (hence the need for M to be "large enough.")
See also
Two phase method (linear programming) another approach for solving problems with >= constraints
Karush–Kuhn–Tucker conditions, which apply to nonlinear optimization problems with inequality constraints.
External links
Bibliography
Discussion
Simplex – Big M Method, Lynn Killen, Dublin City University.
The Big M Method, businessmanagementcourses.org
The Big M Method, Mark Hutchinson
The Big-M Method with the Numerical Infinite M, a recently introduced parameterless variant
A THREE-PHASE SIMPLEX METHOD FOR INFEASIBLE AND UNBOUNDED LINEAR PROGRAMMING PROBLEMS, Big M method for M=1
References
Linear programming
Linear algebra | Big M method | Mathematics | 777 |
347,005 | https://en.wikipedia.org/wiki/RELAX%20NG | In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML—a RELAX NG schema specifies a pattern for the structure and content of an XML document. A RELAX NG schema is itself an XML document but RELAX NG also offers a popular compact, non-XML syntax. Compared to other XML schema languages RELAX NG is considered relatively simple.
It was defined by a committee specification of the OASIS RELAX NG technical committee in 2001 and 2002, based on Murata Makoto's RELAX and James Clark's TREX, and also by part two of the international standard ISO/IEC 19757: Document Schema Definition Languages (DSDL). ISO/IEC 19757-2 was developed by ISO/IEC JTC 1/SC 34 and published in its first version in 2003.
Schema examples
Suppose we want to define an extremely simple XML markup scheme for a book: a book is defined as a sequence of one or more pages; each page contains text only. A sample XML document instance might be:
<book>
<page>This is page one.</page>
<page>This is page two.</page>
</book>
XML syntax
A RELAX NG schema can be written in a nested structure by defining a root element that contains further element definitions, which may themselves contain embedded definitions. A schema for our book in this style, using the full XML syntax, would be written:
<element name="book" xmlns="http://relaxng.org/ns/structure/1.0">
<oneOrMore>
<element name="page">
<text/>
</element>
</oneOrMore>
</element>
Nested structure becomes unwieldy with many sublevels and cannot define recursive elements, so most complex RELAX NG schemas use references to named pattern definitions located separately in the schema. Here, a "flattened schema" defines precisely the same book markup as the previous example:
<grammar xmlns="http://relaxng.org/ns/structure/1.0">
<start>
<element name="book">
<oneOrMore>
<ref name="page"/>
</oneOrMore>
</element>
</start>
<define name="page">
<element name="page">
<text/>
</element>
</define>
</grammar>
Compact syntax
RELAX NG compact syntax is a non-XML format inspired by extended Backus–Naur form and regular expressions, designed so that it can be unambiguously translated to its XML counterpart, and back again, with one-to-one correspondence in structure and meaning, in much the same way that Simple Outline XML (SOX) relates to XML. It shares many features with the syntax of DTDs. Here is the compact form of the above schema:
element book {
element page { text }+
}
With named patterns, this can be flattened to:
start = element book { page+ }
page = element page { text }
A compact RELAX NG parser will treat these two as the same pattern.
Comparison with W3C XML Schema
Although the RELAX NG specification was developed at roughly the same time as the W3C XML Schema specification, the latter was arguably better known and more widely implemented in both open-source and proprietary XML parsers and editors when it became a W3C Recommendation in 2001. Since then, however, RELAX NG support has increasingly found its way into XML software, and its acceptance has been aided by its adoption as a primary schema for popular document-centric markup languages such as DocBook, the TEI Guidelines, OpenDocument, and EPUB.
RELAX NG shares with W3C XML Schema many features that set both apart from traditional DTDs: data typing, regular expression support, namespace support, ability to reference complex definitions.
Filename extensions
By informal convention, RELAX NG schemas in the regular syntax are typically named with the filename extension ".rng". For schemas in the compact syntax, the extension ".rnc" is used.
Determinism
Relax NG schemas are not necessarily "deterministic" or "unambiguous".
Converting Relax NG to DTD
Relax NG schemas can be converted to DTDs by applying Trang which can be found at: . The manual for Trang is located at . Note that Trang is unable to convert the OASIS DITA 1.3 schema to DTDs, failing with messages like:
sorry, combining definitions with combine="choice" is not supported
See also
XML schemas
DTD (Document Type Definition)
Document Structure Description
XML Schema (W3C)
Schematron
ODD (One Document Does it all)
SXML
References
External links
RELAX NG home page
"The Design of RELAX NG" by James Clark
RELAX NG tutorial for the XML syntax
RELAX NG tutorial for the compact syntax
Design patterns for structuring XML documents
RELAX NG Book by Eric van der Vlist, released under the GNU Free Documentation License
Relax NG Reference by ZVON
RELAX NG Java community projects at java.net
Sun Multi-Schema Validator (MSV) open-source Java XML toolkit
Relax NG Compact Syntax validator open-source C program
XSD to Relax NG Converter Web-based converter
https://github.com/relaxng/jing-trang
Computer-related introductions in 2001
Data modeling languages
ISO/IEC standards
XML
XML-based standards | RELAX NG | Technology | 1,157 |
796,237 | https://en.wikipedia.org/wiki/Mamiya | is a Japanese company that manufactures high-end cameras and other related photographic and optical equipment. With headquarters in Tokyo, it has two manufacturing plants and a workforce of over 200 people. The company was founded in May 1940 by camera designer Seiichi Mamiya () and financial backer Tsunejiro Sugawara.
History
Mamiya originally achieved fame for its professional medium-format rangefinder film cameras such as the Mamiya Six (1940) and the Mamiya Press (1962) series. It later developed medium-format industry workhorse single lens reflex cameras: RB67 (1970), RZ67 (1982), and 645 (1975); and twin-lens reflex C series, all of which were used by advanced amateur and professional photographers.
Many Mamiya models over the past six decades have become collectors' items. The earliest Mamiya Six medium-format folding camera, the 35 mm Mamiya-Sekor 1000DTL, the lightweight 35 mm Mamiya NC1000, the 6×6 cm medium-format C series of interchangeable-lens twin-lens reflex (TLR) cameras, and the press cameras of the Super/Universal series are highly valued. Mamiya also manufactured the last models in the Omega Rapid series of medium format press cameras.
Mamiya has entered other business markets over time by purchasing other companies. Until 2000, it made fishing equipment such as fishing rods and fishing reels. In 2006, the Mamiya Op Co., Ltd., Inc. transferred the camera and optical business to Mamiya Digital Imaging Co., Ltd. The original company, doing business as Mamiya-OP, continues to exist and makes a variety of industrial and electronics products. It also makes golf clubs, golf club shafts and grips, and golf balls through its subsidiaries Kasco and USTMamiya.
Phase One acquisition
In 2009, Phase One, a medium format digital camera back manufacturer from Denmark, purchased a major stake in Mamiya. In 2012, Phase One combined Mamiya and another subsidiary, Leaf Imaging, created a new, worldwide Mamiya Leaf brand to integrate both companies’ product lines into one complete medium-format digital camera system offering. The re-branding offers a streamlined product development and establishment of a more efficient customer sales and support base.
In 2015 Phase One purchased Mamiya and began using Mamiya's Saku factory as the new Japan headquarters.
135 film
Mamiya started manufacturing 135 film cameras in 1949, with point-and-shoot compact cameras being introduced later. The excellent Mamiya-35 series of rangefinder cameras was followed by the Mamiya Prismat SLR in 1961 and the Mamiya TL/DTL in the mid-to-late 1960s. The SX, XTL and NC1000 were other 135 film SLR camera models introduced by Mamiya. One of Mamiya's last 135 film SLR designs was the Z-series. The original entry-level ZE model was an aperture-priority-only SLR; the ZE-2 added manual exposure; the ZE-X added shutter priority and full program automated mode, and (with a dedicated flash and an EF-series lens) focus-priority flash exposure). In these models the aperture ring had no direct connection to the diaphragm, allowing the camera body to override the set aperture, and the lenses could communicate a considerable amount of information to the camera body via electrical contacts on the mount.
The Mamiya ZM, introduced in 1982, was essentially an advanced version of the ZE-2, with some of the features of the ZE-X. It was the last Mamiya 135 film camera produced. It had an aperture-priority automatic time control, based on center-weighted TTL readings, an automatic shutter-speed range from 4 seconds to 1/1000, and a manual range from 2 seconds to 1/1000. Visual and audio signals indicated over- or under-exposure, pending battery failure, or excessive camera shake. Metering modes, shutter release, self-timer, manual time settings and the ergonomics of the camera body were also improved.
In 1984 Osawa, one of Mamiya's major distributors, filed for the Japanese equivalent of bankruptcy and, soon after, Mamiya discontinued 135-film camera production to focus on the medium-format professional market.
Medium format
Common medium format frame sizes on 120 film include 645, 6×6, and 6×7, named for the nominal frame dimensions, in centimeters. These were derived from fractional imperial units, so the actual frame size is slightly different from the nominal dimensions:
645 =
6×6 =
6×7 =
Mamiya made a series of square format (6×6) twin lens reflex (TLR) cameras throughout the middle of the twentieth century. These were developed into the C cameras (C2, C3 through to C330s) which have interchangeable lenses as well as bellows focus.
In 1970, Mamiya introduced the RB67, a 6×7 cm (nominal) professional single lens reflex (SLR). The RB67, a large, heavy, medium-format camera with built-in closeup bellows was innovative and successful. Previous medium-format professional SLR cameras used the square 6×6 cm format which did not require the camera to be rotated for photographs in portrait orientation, problematical with large and heavy cameras when tripod-mounted. Like the Linhof Technika the RB67 had a rotating back which enabled photographs to be taken in either landscape or portrait orientation without rotating the camera, at the expense of additional weight and bulk. The RB67 soon became widely used by professional studio photographers. The 6×7 frame had been introduced and patented by Linhof (56 × 72mm) and was described as being ideal, as the negatives required very little cropping to fit on standard 10" × 8" paper. Mamiya actually used a frame size of 56 × 67mm.
When comparing the RB67 to full frame 135 cameras there is a so-called "crop factor" of ×. That means the standard 35mm frame (36×24 mm) dimension, across the diagonal, is approximately half the corresponding diagonal dimension on the 67 (56×67 mm; note the aspect ratio is different. The total area of the 35mm frame is of the 6×7 frame. This affects the focal length of lenses so that to get an equivalent field of view on a 35mm camera you need half the focal length of a 6×7 lens. There is a similar effect on the depth of field of a particular aperture, so a 90mm lens on the RB67 is equivalent to using a 45mm on 35mm full frame.
In 1975 Mamiya started to offer the M645, the first SLR medium format camera to use the 645 format exclusively. The 645 format was introduced originally in the 1930s. The Mamiya 645 cameras could take 15 shots on a standard 120 roll film.
The RB67 was followed by the more advanced RZ67 6x7cm frame format camera in 1982. These cameras established Mamiya as a major medium-format professional camera manufacturer, together with Hasselblad, Rollei, Bronica and Pentax.
In 1989, Mamiya introduced the Mamiya 6 (6x6cm) rangefinder camera. In 1995, this was followed by the Mamiya 7 (6x7cm). The Mamiya 6 was discontinued around 1999; the Mamiya 7 was produced for 18 years, with production ending around 2013. The Mamiya 6 is more portable due to a collapsible lens mount, while the Mamiya 7 offers a wider variety of lens options. Both the Mamiya 6 and 7 are compact and quiet cameras which are reputed for the extremely high optical quality of their lenses.
In 1999, Mamiya presented the Mamiya 645AF, a 6X4.5 frame SLR camera with interchangeable lenses and film backs, auto focus and an integrated prism visor that would be the base platform for the Mamiya 645AFD film and digital back cameras.
Digital products
Mamiya introduced the Mamiya ZD, which was a compact medium-format camera, in 2004. Rather than taking the form of a digital back solution, it was all built into one unit, much like a 35mm camera. This camera utilized the Mamiya 645AF lenses and had a resolution of 22mp. The solution had technical difficulties and became delayed. At the same time, Mamiya also announced a ZD back which had the same specification but was intended to be used with the Mamiya 645AFDII / AFDIII. The ZD back was even more delayed and, once it was introduced, it was already outdated.
In 2009, the Mamiya M Series digital backs were released (M18, M22 and M31) all featuring high pixel counts with large CCDs and compatibility with the Mamiya 645AFD range and RZ/ RB series (via specially manufactured adapters). All the backs are compatible with 4x5 inch view cameras.
In the final quarter of 2009, Mamiya released its Mamiya 645DF camera, the latest and digital-only version of the famed 6x4.5 format AF camera series. The Mamiya 645DF has many improved features including mirror-up delay, lack of shutter lag, AF preference with priority on speed or precision, and compatibility with the new leaf shutter lens range (Mamiya Sekor AF 80mm, 55mm and 110mm D lenses with in-built leaf shutters). With these lenses attached, flash synchronizations speeds of up to 1/1,600 of a second are achievable, although the camera can also be programmed to use the focal plane shutter even if a leaf shutter lens is attached. 2010 saw the release of 3 Mamiya DM Systems (Mamiya DM33 System, consisting of a 645DF camera body and 33MP digital back, the Mamiya DM28 System, consisting of a 645 AF III camera body and 28MP digital back, and the Mamiya DM22 System, consisting of a 645 AF III camera body and 22MP digital back. A new logo and webpage were also launched.
Mamiya America Corporation
In the United States, the trademark for "Mamiya" was not owned by the original company in Japan but rather by a wholly separate entity called Mamiya America Corporation ("M.A.C."). As such, all products that bear the name "Mamiya" were controlled by M.A.C. and resulted in considerably higher retail prices compared to outside the United States.
As of 2014 MAC group no longer manages the Mamiya brand in America, all sales, service and support was transferred to Phase One who already owned a large portion of Mamiya.
Products
Medium Format Professional
6×4.5 cm format
Single-lens reflex cameras
Mamiya 645
6×6 cm format
Twin-lens reflex cameras
Mamiyaflex C Professional (1956)
Mamiyaflex PF (1957) police model
Mamiyaflex C2 Professional (1958)
Mamiya C3 Professional (1962)
Mamiya C33 Professional (1965)
Mamiya C22 Professional (1966)
Mamiya C220 Professional (1968)
Mamiya C330 Professional (1969)
Mamiya C330f Professional (1975)
Mamiya C220f Professional (1982)
Mamiya C330s Professional (1983)
Rangefinder camera
Mamiya 6 — electronic 6 cm × 6 cm rangefinder camera
6×7 cm format
Single-lens reflex cameras
Mamiya RB67 Professional (1970) — mechanical 6 cm × 7 cm SLR medium-format camera
Mamiya RB67 Professional S (1974) — minor changes
Mamiya RB67 Professional GL (1982) — special edition of the Pro-S
Mamiya RB67 Professional SD (1990) — new, larger lens throat; older lenses require an adapter
Mamiya RZ67 Professional (1982) — electronic 6 cm × 7 cm SLR medium-format camera
Mamiya RZ67 Professional II (1995) — upgraded electronics
Mamiya RZ67 Professional IID (2004-2014) — added communication interface for digital backs
Rangefinder cameras
Mamiya 7 (1995–1999) — electronic 6 cm × 7 cm rangefinder camera
Mamiya 7 II (1999-2011) — added multi-exposure capability and other minor improvements
6×9 cm format
Rangefinder cameras
Mamiya Press
35mm format
Lenses
See also
List of photographic equipment makers
References
External links
Mamiya Leaf
Mamiya Digital Imaging Co., Ltd. (Mamiya Japan)
マミヤ・オーピー (Mamiya Op Co., Ltd.) separate electronic and golf products company
Cameras
Photography equipment manufacturers of Japan
Electronics companies of Japan
Technology companies established in 1940
Manufacturing companies based in Tokyo
Japanese brands
1940 establishments in Japan | Mamiya | Technology | 2,647 |
36,687,157 | https://en.wikipedia.org/wiki/Indian%20Airlines%20Flight%20171 | Indian Airlines Flight 171 was a Caravelle that crashed while attempting an emergency landing at Bombay Airport (now Chhatrapati Shivaji Maharaj International Airport) on 12 October 1976 after suffering an uncontained engine failure, killing all 95 people on board. Metal fatigue in the No. 2 engine's 10th stage high-pressure compressor disk had caused it to disintegrate, the resulting fragments severed fuel lines causing fuel to leak into the engine and ignite causing an uncontrolled fire that eventually affected control surfaces leading to a loss of control.
Accident
Flight 171 was a scheduled domestic passenger flight from Bombay (now Mumbai) to Madras (now Chennai). A Boeing aircraft was originally supposed to make the flight but it developed engine trouble and was replaced with a Sud Aviation Caravelle. Shortly after takeoff from runway 27, Flight 171 suffered a No. 2 engine failure. The crew of Flight 171 immediately turned back to attempt an emergency landing on Bombay Airport's runway 09. With its undercarriage down approximately from the end of the runway and while at an altitude of , the aircraft suffered a loss of control and plummeted into the ground. Everyone on board Flight 171 perished in the accident.
Cause
A fatigue crack in the tenth stage compressor disc caused a power plant failure which was followed by the bursting of the compressor casing and the cutting of fuel lines that spanned the structure. This caused an intense in-flight fire in the engine bay. It is believed the fire consumed the Caravelle's supply of hydraulic fluid and this was the cause of the aircraft going out of control.
Passengers
Indian actress Rani Chandra died in the accident while actor Jeetendra had planned to board the airliner but cancelled. The actor said that because it was Karwa Chauth, his wife asked him to delay his trip, but Jeetendra decided to head to the airport anyway. After reaching the airport, he realised that the flight was late and decided to go back home to help his wife break her fast. Subsequently, his wife did not allow him to return to the airport, and hours later he read that the plane had burst into flames mid-air.
References
External links
1976 in India
Aviation accidents and incidents in 1976
Airliner accidents and incidents caused by in-flight fires
Airliner accidents and incidents caused by mechanical failure
Aviation accidents and incidents in India
Accidents and incidents involving the Sud Aviation Caravelle
171
October 1976 events in Asia
Airliner accidents and incidents involving uncontained engine failure
Airliner accidents and incidents caused by engine failure | Indian Airlines Flight 171 | Materials_science | 512 |
1,439,214 | https://en.wikipedia.org/wiki/Hermann%20Oberth%20Space%20Travel%20Museum | The Hermann Oberth Space Travel Museum (Hermann-Oberth-Raumfahrt-Museum, or Hermann-Oberth-Museum for short) is a museum of space technology in the Franconian city of Feucht in Bavaria, Germany.
It commemorates the life work of the famous visionary and rocket pioneer Hermann Oberth. Exhibits include a Kumulus rocket and a Cirrus rocket, which were developed at the beginning of the 1960s by the Hermann Oberth Society and launched near Cuxhaven, Germany. A Swiss Zenit sounding rocket is also on display in front of the museum.
References
External links
Hermann-Oberth-Raumfahrt-Museum home page
Museums in Bavaria
Rocketry
Aerospace museums in Germany
Science museums in Germany
Buildings and structures in Nürnberger Land
Museums established in 1971
1971 establishments in West Germany | Hermann Oberth Space Travel Museum | Engineering | 169 |
1,365,931 | https://en.wikipedia.org/wiki/Universal%20indicator | A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a solution.
History
Although there are several commercially available universal pH indicators, most are a variation of a formula patented by Yamada in 1933.
Composition
A universal indicator is usually composed of water, 1-propanol, phenolphthalein, sodium hydroxide, methyl red, bromothymol blue, sodium bisulfite, and thymol blue. The colours that indicate the pH of a solution, after adding a universal indicator, are:
The colors from yellow to red indicate an acidic solution, colours blue to violet indicate an alkaline solution and a green colour indicates that a solution is neutral.
Wide-range pH test papers with distinct colours for each pH from 1 to 14 are also available. Colour matching charts are supplied with the specific test strips purchased.
Types
Paper form: It is a strip of coloured paper which changes colour to red if the solution is acidic and to blue, if the solution is basic. The strip can be placed directly onto a surface of a wet substance or a few drops of the solution can be dropped onto the universal indicator using dropping equipment. If the test solution is of a dark colour, it is preferable to use a paper universal indicator, such as Hydrion paper.
Solution: The main components of a universal indicator, in the form of a solution, are thymol blue, methyl red, bromothymol blue, and phenolphthalein. This mixture is important because each component loses or gains protons depending upon the acidity or alkalinity of the solution being tested. It is beneficial to use this type of universal indicator in a colorless solution. This will increase the accuracy level of indication.
Influence on conductivity
The impact of an ethanol-based universal indicator may seem negligible at first glance. However, in the case of dilute solutions prepared with bidistilled water, this influence becomes readily discernible and measurable.
See also
Litmus
pH indicator
References
PH indicators | Universal indicator | Chemistry,Materials_science | 454 |
21,057,248 | https://en.wikipedia.org/wiki/Voronoi%20deformation%20density | Voronoi deformation density (VDD) is a method employed in computational chemistry to compute the atomic charge distribution of a molecule in order to provide information about its chemical properties. The method is based on the partitioning of space into non-overlapping atomic areas modelled as Voronoi cells and then computing the deformation density within those cells (i.e. the extent to which electron density differs from that of an unbonded atom).
The VDD charge QA of atom A is computed as the (numerical) integral of the deformation density ∆ρ(r) = ρ(r) – ΣBρB(r) associated with the formation of the molecule from its atoms over the volume of the Voronoi cell of atom A:
The Voronoi cell of atom A is defined as the compartment of space bounded by the bond midplanes on and perpendicular to all bond axes between nucleus A and its neighboring nuclei (cf. the Wigner–Seitz cells in crystals). The Voronoi cell of atom A is therefore the region of space closer to nucleus A than to any other nucleus. Furthermore, ρ(r) is the electron density of the molecule and ΣBρB(r) the superposition of atomic densities ρB of a fictitious promolecule without chemical interactions that is associated with the situation in which all atoms are neutral.
Note that an atomic charge is not a physical observable. Nevertheless, it has been proven a useful means to compactly describe and analyze the electron density distribution in a molecule, which is important for understanding the behavior of the latter. In this connection, it is an asset of VDD atomic charges QA that they have a rather straightforward and transparent interpretation. Instead of measuring the amount of charge associated with a particular atom A, QA directly monitors how much charge flows, due to chemical interactions, out of (QA > 0) or into (QA < 0) the Voronoi cell of atom A, that is, the region of space that is closer to nucleus A than to any other nucleus.
See also
Partial charge
References
Computational chemistry | Voronoi deformation density | Chemistry | 428 |
25,116,263 | https://en.wikipedia.org/wiki/Patriarch%20hypothesis | The patriarch hypothesis is a hypothesis that explains the occurrence of menopause in human females and how a long post-fertile period (up to one third of a female's life-span) could confer an evolutionary advantage. It is an alternative theory to the grandmother hypothesis which tends to ignore male benefits of continued spermatogenesis and their roles in assistance.
The patriarch hypothesis incorporates these neglected areas. It suggests selection pressure on male longevity extended the female lifespan; whose adjustment of life history has been constrained by the size of the ovaries – resulting in human females surviving beyond the age at which they can reproduce. With an extension of the post-reproductive female life stage, they could enhance their inclusive fitness by giving kin assistance. This way, with no choice in the timing of fertility termination, females are optimising an essentially bad situation.
Frank Marlowe first put forward the patriarch hypothesis. He postulates that if women survive beyond an age at which they can reproduce and men continue spermatogenesis, then old males can benefit greatly if they can copulate with younger females. It is theorised that increased use of tools and weapons compensates for the decline in natural fighting ability with age. This serves to produce a more stable male hierarchy, where attainment of high social status and reproductive access is less reliant on physical strength.
With such a scenario older males are able to retain a competitive ability with younger males, thereby asserting a selection pressure on extending longevity in males that could retain social status. Higher ranking males may also be a more attractive mate choice. One mechanism that could extend the lifespan is delaying the age at maturity. Offspring with a slower life history would exhibit a protracted period of dependence. If depletion of oocytes occurs at age 50, females should selectively counter this as it reduces their fecundity.
Recruitment of help from kin and husbands may compensate by enabling females to reduce birth intervals by weaning offspring at an earlier age. In addition, by passing on longevity to her sons, a female would stand to gain inclusive fitness.
Criticism
Some of the criticisms include the fact that actually most fathers, especially first time fathers, are predominantly under 40, and only one percent of 1st time fathers are above 50. Even in today's hunter-gather societies, younger males are preferred by women and their parents as husbands, as hunting and rearing children require extensive strength that tools can't compensate for in elderly males. And because demographic data has shown that historically rising numbers in older people among the population correlated with lower numbers of younger people, this means that more elderly men do not result in more children, quite the opposite. Frank Marlowe also fails to explain the pressure on men to reproduce in later life, especially with the fact that the genetic quality and the survival of a fetus of an elderly male is lower than that with a young father, making having a child with an elderly man risky for a woman. It also fails to consider the fact that reproducing sperm is much less costly than reproducing eggs, bearing the young and feeding them, which means there is no need for the elderly man to stop his spermatogenesis even if it's almost useless. Furthermore, men are much more likely to die earlier than women and have more cancers than them, sex hormones play a significant role in this.
Evidence for
The patriarch hypothesis rests on three assumptions:
Older males can reproduce.
It is clear that older males do reproduce, as the oldest verified paternity is 94 years, 35 years beyond the oldest documented birth attributed to females.
The allele for slowing life history and extending longevity is not on the Y chromosome.
To date a ‘longevity’ gene(s) is still elusive. However, INK4a/ARF situated on the human chromosome 9p21 does appear to act as a tumour suppressor therefore extending longevity.
Increasing the ovarian follicular reserve is difficult.
There are few explanations on density restrictive mechanisms other than physical size. NOS3 has been proposed as a candidate gene for the regulation and timing of reproductive functions, such as menopause, although it is unclear why timing has not adjusted with longevity. More importantly there is a lack of understanding why 70–99.9% of mammalian follicles are subjected to atresia. Future analysis of the differential expression of genes of the bcl-2 family may hold the key.
Longevity is a central determinant of the grandmother hypothesis; selection for greater longevity in males, as suggested by the patriarch hypothesis, could extend female lifespan, provided such a gene is not on the Y chromosome. Males have much to gain from late reproduction, even if they die shortly after conception. Females that found their longevity extended, were constrained by the difficulties of increasing their follicular reserves and thus could enhance their inclusive fitness by giving kin assistance.
However, the hypothesis is committing a fallacy in which it starts with the conclusion that it's supposed to prove. The author starts with the fact that women go through menopause to reach a conclusion of male longevity instead of trying to prove it.
References
Gerontology
Human evolution | Patriarch hypothesis | Biology | 1,039 |
63,104,549 | https://en.wikipedia.org/wiki/Xiaomi%20Mi%2010 | The Xiaomi Mi 10 and Xiaomi Mi 10 Pro are high-end Android smartphones developed by Xiaomi Inc. It is the Xiaomi's first high-end smartphone and announced on 13 February 2020.
Specifications
Design
The Mi 10 and Mi 10 Pro use an aluminum frame and Gorilla Glass 5 on the front and rear. The display is curved and larger than the Mi 9; a circular cutout in the upper left hand corner for the front-facing camera replaces the Mi 9's notch. The camera module resembles the Mi CC9 Pro/Mi Note 10 with the accent ring from the Mi 9 around the top sensor, although the flash is located below in place of the macro sensor. The bottom sensor is likewise separate from the main camera array, and both protrude slightly. The Mi 10 is available in Ice Blue, Peach Gold and Titanium Silver, while the Mi 10 Pro is available in Pearl White and Starry Blue.
Hardware
The Xiaomi Mi 10 and Mi 10 Pro are powered by the Qualcomm Snapdragon 865 processor, with the Adreno 650 GPU. They have a FHD+ Super AMOLED display at a 90 Hz refresh rate with HDR10+ support. There is an optical (in-display) fingerprint scanner as well. Both have 8 GB or 12 GB LPDDR5 RAM, and 128 GB, 256 GB or 512 GB of non-expandable UFS 3.0. The Mi 10's battery is 4780 mAh and the Mi 10 Pro's is slightly smaller at 4500 mAh. The devices can be recharged over USB-C at up to 30 W for the Mi 10 and 50 W for the Mi 10 Pro, and can also charge wirelessly at up to 30 W with reverse charging at 10 W. The Mi 10 and Mi 10 Pro feature quad camera setups. While both come with a 108 MP wide sensor, the Mi 10 has a 13 MP ultrawide sensor and 2 MP macro and depth sensors, while the Mi 10 Pro has a 20 MP ultrawide sensor, a 12 MP portrait sensor and an 8 MP telephoto sensor. Both are capable of recording video at 8K resolution. The front-facing camera on both devices uses a 20 MP sensor.
Software
The devices run on Android 10, with Xiaomi's custom MIUI 11 skin. Later they were updated to MIUI 13 based on Android 12.
As of 2024, Xiaomi Mi 10 and Xiaomi Mi 10 Pro received HyperOS 1 based on Android 13.
Reception
DXOMARK gave the Mi 10 Pro's camera an overall score of 124, with a photo score of 134 and a video score of 104, ranking it as their best smartphone camera at the time.
References
External links
Android (operating system) devices
Phablets
Mobile phones introduced in 2020
Mobile phones with multiple rear cameras
Mobile phones with 8K video recording
Mobile phones with infrared transmitter
Discontinued flagship smartphones
Xiaomi smartphones | Xiaomi Mi 10 | Technology | 608 |
274,536 | https://en.wikipedia.org/wiki/Martingale%20%28probability%20theory%29 | In probability theory, a martingale is a sequence of random variables (i.e., a stochastic process) for which, at a particular time, the conditional expectation of the next value in the sequence is equal to the present value, regardless of all prior values.
History
Originally, martingale referred to a class of betting strategies that was popular in 18th-century France. The simplest of these strategies was designed for a game in which the gambler wins their stake if a coin comes up heads and loses it if the coin comes up tails. The strategy had the gambler double their bet after every loss so that the first win would recover all previous losses plus win a profit equal to the original stake. As the gambler's wealth and available time jointly approach infinity, their probability of eventually flipping heads approaches 1, which makes the martingale betting strategy seem like a sure thing. However, the exponential growth of the bets eventually bankrupts its users due to finite bankrolls. Stopped Brownian motion, which is a martingale process, can be used to model the trajectory of such games.
The concept of martingale in probability theory was introduced by Paul Lévy in 1934, though he did not name it. The term "martingale" was introduced later by , who also extended the definition to continuous martingales. Much of the original development of the theory was done by Joseph Leo Doob among others. Part of the motivation for that work was to show the impossibility of successful betting strategies in games of chance.
Definitions
A basic definition of a discrete-time martingale is a discrete-time stochastic process (i.e., a sequence of random variables) X1, X2, X3, ... that satisfies for any time n,
That is, the conditional expected value of the next observation, given all the past observations, is equal to the most recent observation.
Martingale sequences with respect to another sequence
More generally, a sequence Y1, Y2, Y3 ... is said to be a martingale with respect to another sequence X1, X2, X3 ... if for all n
Similarly, a continuous-time martingale with respect to the stochastic process Xt is a stochastic process Yt such that for all t
This expresses the property that the conditional expectation of an observation at time t, given all the observations up to time , is equal to the observation at time s (of course, provided that s ≤ t). The second property implies that is measurable with respect to .
General definition
In full generality, a stochastic process taking values in a Banach space with norm is a martingale with respect to a filtration and probability measure if
Σ∗ is a filtration of the underlying probability space (Ω, Σ, );
Y is adapted to the filtration Σ∗, i.e., for each t in the index set T, the random variable Yt is a Σt-measurable function;
for each t, Yt lies in the Lp space L1(Ω, Σt, ; S), i.e.
for all s and t with s < t and all F ∈ Σs,
where χF denotes the indicator function of the event F. In Grimmett and Stirzaker's Probability and Random Processes, this last condition is denoted as
which is a general form of conditional expectation.
It is important to note that the property of being a martingale involves both the filtration and the probability measure (with respect to which the expectations are taken). It is possible that Y could be a martingale with respect to one measure but not another one; the Girsanov theorem offers a way to find a measure with respect to which an Itō process is a martingale.
In the Banach space setting the conditional expectation is also denoted in operator notation as .
Examples of martingales
An unbiased random walk, in any number of dimensions, is an example of a martingale. For example, consider a 1-dimensional random walk where at each time step a move to the right or left is equally likely.
A gambler's fortune (capital) is a martingale if all the betting games which the gambler plays are fair. The gambler is playing a game of coin flipping. Suppose Xn is the gambler's fortune after n tosses of a fair coin, such that the gambler wins $1 if the coin toss outcome is heads and loses $1 if the coin toss outcome is tails. The gambler's conditional expected fortune after the next game, given the history, is equal to his present fortune. This sequence is thus a martingale.
Let Yn = Xn2 − n where Xn is the gambler's fortune from the prior example. Then the sequence {Yn : n = 1, 2, 3, ... } is a martingale. This can be used to show that the gambler's total gain or loss varies roughly between plus or minus the square root of the number of games of coin flipping played.
de Moivre's martingale: Suppose the coin toss outcomes are unfair, i.e., biased, with probability p of coming up heads and probability q = 1 − p of tails. Let
with "+" in case of "heads" and "−" in case of "tails". Let
Then {Yn : n = 1, 2, 3, ... } is a martingale with respect to {Xn : n = 1, 2, 3, ... }. To show this
Pólya's urn contains a number of different-coloured marbles; at each iteration a marble is randomly selected from the urn and replaced with several more of that same colour. For any given colour, the fraction of marbles in the urn with that colour is a martingale. For example, if currently 95% of the marbles are red then, though the next iteration is more likely to add red marbles than another color, this bias is exactly balanced out by the fact that adding more red marbles alters the fraction much less significantly than adding the same number of non-red marbles would.
Likelihood-ratio testing in statistics: A random variable X is thought to be distributed according either to probability density f or to a different probability density g. A random sample X1, ..., Xn is taken. Let Yn be the "likelihood ratio"
If X is actually distributed according to the density f rather than according to g, then {Yn :n=1, 2, 3,...} is a martingale with respect to {Xn :n=1, 2, 3, ...}
In an ecological community, i.e. a group of species that are in a particular trophic level, competing for similar resources in a local area, the number of individuals of any particular species of fixed size is a function of (discrete) time, and may be viewed as a sequence of random variables. This sequence is a martingale under the unified neutral theory of biodiversity and biogeography.
If { Nt : t ≥ 0 } is a Poisson process with intensity λ, then the compensated Poisson process { Nt − λt : t ≥ 0 } is a continuous-time martingale with right-continuous/left-limit sample paths.
Wald's martingale
A -dimensional process in some space is a martingale in if each component is a one-dimensional martingale in .
Submartingales, supermartingales, and relationship to harmonic functions
There are two generalizations of a martingale that also include cases when the current observation Xn is not necessarily equal to the future conditional expectation E[Xn+1 | X1,...,Xn] but instead an upper or lower bound on the conditional expectation. These generalizations reflect the relationship between martingale theory and potential theory, that is, the study of harmonic functions. Just as a continuous-time martingale satisfies E[Xt | {Xτ : τ ≤ s}] − Xs = 0 ∀s ≤ t, a harmonic function f satisfies the partial differential equation Δf = 0 where Δ is the Laplacian operator. Given a Brownian motion process Wt and a harmonic function f, the resulting process f(Wt) is also a martingale.
A discrete-time submartingale is a sequence of integrable random variables satisfying
Likewise, a continuous-time submartingale satisfies
In potential theory, a subharmonic function f satisfies Δf ≥ 0. Any subharmonic function that is bounded above by a harmonic function for all points on the boundary of a ball is bounded above by the harmonic function for all points inside the ball. Similarly, if a submartingale and a martingale have equivalent expectations for a given time, the history of the submartingale tends to be bounded above by the history of the martingale. Roughly speaking, the prefix "sub-" is consistent because the current observation Xn is less than (or equal to) the conditional expectation E[Xn+1 | X1,...,Xn]. Consequently, the current observation provides support from below the future conditional expectation, and the process tends to increase in future time.
Analogously, a discrete-time supermartingale satisfies
Likewise, a continuous-time supermartingale satisfies
In potential theory, a superharmonic function f satisfies Δf ≤ 0. Any superharmonic function that is bounded below by a harmonic function for all points on the boundary of a ball is bounded below by the harmonic function for all points inside the ball. Similarly, if a supermartingale and a martingale have equivalent expectations for a given time, the history of the supermartingale tends to be bounded below by the history of the martingale. Roughly speaking, the prefix "super-" is consistent because the current observation Xn is greater than (or equal to) the conditional expectation E[Xn+1 | X1,...,Xn]. Consequently, the current observation provides support from above the future conditional expectation, and the process tends to decrease in future time.
Examples of submartingales and supermartingales
Every martingale is also a submartingale and a supermartingale. Conversely, any stochastic process that is both a submartingale and a supermartingale is a martingale.
Consider again the gambler who wins $1 when a coin comes up heads and loses $1 when the coin comes up tails. Suppose now that the coin may be biased, so that it comes up heads with probability p.
If p is equal to 1/2, the gambler on average neither wins nor loses money, and the gambler's fortune over time is a martingale.
If p is less than 1/2, the gambler loses money on average, and the gambler's fortune over time is a supermartingale.
If p is greater than 1/2, the gambler wins money on average, and the gambler's fortune over time is a submartingale.
A convex function of a martingale is a submartingale, by Jensen's inequality. For example, the square of the gambler's fortune in the fair coin game is a submartingale (which also follows from the fact that Xn2 − n is a martingale). Similarly, a concave function of a martingale is a supermartingale.
Martingales and stopping times
A stopping time with respect to a sequence of random variables X1, X2, X3, ... is a random variable τ with the property that for each t, the occurrence or non-occurrence of the event τ = t depends only on the values of X1, X2, X3, ..., Xt. The intuition behind the definition is that at any particular time t, you can look at the sequence so far and tell if it is time to stop. An example in real life might be the time at which a gambler leaves the gambling table, which might be a function of their previous winnings (for example, he might leave only when he goes broke), but he can't choose to go or stay based on the outcome of games that haven't been played yet.
In some contexts the concept of stopping time is defined by requiring only that the occurrence or non-occurrence of the event τ = t is probabilistically independent of Xt + 1, Xt + 2, ... but not that it is completely determined by the history of the process up to time t. That is a weaker condition than the one appearing in the paragraph above, but is strong enough to serve in some of the proofs in which stopping times are used.
One of the basic properties of martingales is that, if is a (sub-/super-) martingale and is a stopping time, then the corresponding stopped process defined by is also a (sub-/super-) martingale.
The concept of a stopped martingale leads to a series of important theorems, including, for example, the optional stopping theorem which states that, under certain conditions, the expected value of a martingale at a stopping time is equal to its initial value.
See also
Azuma's inequality
Brownian motion
Doob martingale
Doob's martingale convergence theorems
Doob's martingale inequality
Doob–Meyer decomposition theorem
Local martingale
Markov chain
Markov property
Martingale (betting system)
Martingale central limit theorem
Martingale difference sequence
Martingale representation theorem
Normal number
Semimartingale
Notes
References
Entire issue dedicated to Martingale probability theory (Laurent Mazliak and Glenn Shafer, Editors).
Stochastic processes
Martingale theory
Game theory
Paul Lévy (mathematician) | Martingale (probability theory) | Mathematics | 2,938 |
5,797,443 | https://en.wikipedia.org/wiki/Malcolm%20Green%20%28chemist%29 | Malcolm Leslie Hodder Green (16 April 1936 – 24 July 2020) was Professor of Inorganic Chemistry at the University of Oxford. He made many contributions to organometallic chemistry.
Education
Born in Eastleigh, Hampshire, he was educated at Denstone College and received his Bachelor of Science degree from Acton Technical College (London University External Regulations) in 1956 and his PhD from Imperial College of Science and Technology in 1959 for research carried out under the supervision of Geoffrey Wilkinson.
Career
After his PhD, Green undertook a postdoctoral research year with Wilkinson before moving to the University of Cambridge in 1960 as Assistant Lecturer and being appointed a Fellow of Corpus Christi College, Cambridge in 1961. In 1963 he was appointed a Septcentenary Fellow of Inorganic Chemistry at Balliol College, Oxford and a Departmental Demonstrator at the University of Oxford. In 1965 he was made a Lecturer and he was also a Royal Society Senior Research Fellow in Oxford 1979–86. In 1989 he was appointed Professor of Inorganic Chemistry and Head of the Inorganic Chemistry Laboratory at Oxford and Fellow of St Catherine's College, Oxford. In 2004 he became an Emeritus Research Professor. He was a co-founder of the Oxford Catalysts Group plc in 2006.
Green held many visiting positions including: Visiting Professor, Ecole de Chimie and Institute des Substances Naturelles, Paris (1972), Alfred P. Sloan Visiting Professor, Harvard University (1975), Sherman Fairchild Visiting Scholar at the California Institute of Technology (1981), and Walter Hieber Gastprofessor, University of Munich, Germany (1991).
Research
Green's earliest publications described metal-hydride and metal-olefin complexes, themes that he pursued throughout his career. Many of his early contributions focused on the chemistry of molybdocene dihydride ((C5H5)2MoH2) and the related tungsten derivative. These compounds were shown to engage in many reactions related to C-H bond activation.
With Rooney, he was an active proponent of various mechanisms to explain stereochemistry in Ziegler–Natta polymerisation. He used metal vapour synthesis, especially for the preparation of early metal sandwich complexes. He and his students synthesised several examples of complexes exhibiting "agostic" bonds. The word was suggested to him by Jasper Griffin, professor of Classics at Balliol, whom Green asked for an appropriate Greek word to describe the close bonding phenomenon. This work would later lead to the so-called "modified Green-Rooney mechanism" for Ziegler–Natta catalysis, wherein agostic interactions guide the stereochemistry of the alkene insertion step. This proposal found wide acceptance. His work on metal carbide catalysts led to the corporate spin-off company Oxford Catalysts plc, which became Velocys.
Green along with Stephen G. Davies and Michael Mingos compiled a set of rules that summarise where nucleophilic additions will occur on pi ligands known as the Green–Davies–Mingos rules. His former doctoral students include Vernon C. Gibson.
Green developed the covalent bond classification (CBC) method in 1995 to describe the ligands and bonding in coordination and organometallic complexes.
Towards the end of his career Green's interests shifted to include studies of carbon nanotubes, developing methods to "uncap" (open) them, and investigating their filling with metals and with salts.
Awards and honours
His numerous awards include:
1972: Awarded the Corday-Morgan medal in Inorganic Chemistry by the Royal Society of Chemistry (RSC)
1977: Medal in Transition Metal Chemistry from the RSC
1982: Tilden Prize and Lectureship, RSC
1984: American Chemical Society Award in Inorganic Chemistry
1985: Elected a Fellow of the Royal Society (FRS)
1985: Medal in Organometallic Chemistry, RSC
1988: Sir Edward Frankland Prize Lecturership, RSC
1995: Awarded the Davy Medal by the Royal Society
1997: Medal in Organometallic Chemistry from the American Chemical Society
1992: From the Gesellschaft Deutscher Chemiker, the Karl-Ziegler Prize
2000: Sir Geoffrey Wilkinson Medal and Prize, RSC
Elected a Fellow of the Royal Society of Chemistry (FRSC)
2015: From the European Association for Chemical and Molecular Sciences, the European Prize for Organometallic Chemistry
See also
Single-walled carbon nanohorn
References
1936 births
2020 deaths
Inorganic chemists
English chemists
Carbon scientists
People educated at Denstone College
Alumni of University of London Worldwide
Alumni of the University of London
Alumni of the University of Cambridge
Alumni of the University of Oxford
Alumni of Imperial College London
Fellows of Balliol College, Oxford
Fellows of the Royal Society
Fellows of the Royal Society of Chemistry
People from Eastleigh
Harvard University staff
Academic staff of the Ludwig Maximilian University of Munich
Members of the University of Cambridge Department of Chemistry
Fellows of Corpus Christi College, Cambridge
Academics of the University of Oxford
Fellows of St Catherine's College, Oxford | Malcolm Green (chemist) | Chemistry | 1,000 |
36,763,436 | https://en.wikipedia.org/wiki/Boron%20aluminum%20titanium%20hydride | Boron Aluminum Titanium Hydride (BATH) was developed as a radiation shielding material in the NERVA project for space nuclear thermal propulsion applications. It is a metal matrix composite, consisting of particles of boron carbide (29.5–30.8 wt%) and titanium hydride (4.7–5.1 wt%) embedded in an aluminium matrix (64.1 wt%).
References
Space science
Metal matrix composites | Boron aluminum titanium hydride | Physics,Astronomy | 97 |
27,260,042 | https://en.wikipedia.org/wiki/Delegation%20%28computer%20security%29 | Delegation is the process of a computer user handing over its authentication credentials to another user. In role-based access control models, delegation of authority involves delegating roles that a user can assume or the set of permissions that the user can acquire, to other users.
Types of delegation in IT networks
There are essentially two classes of delegation: delegation at Authentication/Identity Level, and delegation at Authorization/Access Control Level.
Delegation at Authentication/Identity level
It is defined as follows: If an authentication mechanism provides an effective identity different from the validated identity of the user then it is called identity delegation at
the authentication level, provided the owner of the effective identity has previously
authorized the owner of the validated identity to use his identity.
The existing techniques of identity delegation using sudo or su commands of UNIX are very popular. To use the sudo command, a person first has to start his session with his own original identity. It requires the delegated account password or explicit authorizations granted by the system administrator. The user login delegation described in the patent of Mercredi and Frey is also an identity delegation.
Delegation at Authorization/Access Control level
The most common way of ensuring computer security is access control mechanisms provided by operating systems such as UNIX, Linux, Windows, Mac OS, etc.
If the delegation is for very specific rights, also known as fine-grained, such as with Role-based access control (RBAC) delegation, then there is always a risk of under-delegation, i.e., the delegator does not delegate all the necessary permissions to perform a delegated job. This may cause the denial of service, which is very undesirable in some environments, such as in safety critical systems or in health care. In RBAC-based delegation, one option to achieve delegation is by reassigning a set of permissions to the role of a delegatee; however, finding the relevant permissions for a particular job is not an easy task for large and complex systems. Moreover, by assigning these permissions to a delegatee role, all other users who are associated with that particular role get the delegated rights.
If the delegation is achieved by assigning the roles of a delegator to a delegatee then it would not only be a case of over-delegation but also the problem that the delegator has to figure out what roles, in the complex hierarchy of RBAC, are necessary to perform a particular job. These types of problems are not present in identity delegation mechanisms and normally the user interface is simpler.
More details can be found at RBAC.
References
Computer access control | Delegation (computer security) | Engineering | 535 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.