USS Chauncey (DD-3)

The first USS "Chauncey" (Destroyer No. 3/DD-3) was a , also referred to as a "Torpedo-boat destroyer", in the United States Navy named for Commodore Isaac Chauncey. She was launched in 1901 and sunk in 1917.
Construction and design.
"Chauncey" was laid down at Neafie and Levy Ship and Engine Building Company of Philadelphia, Pennsylvania on 2 December 1899 as a member of the "Bainbridge" class, and was launched on 26 October 1901.
"Chauncey" was long overall and at the waterline, with a beam of and a draft of . As the "Bainbridge" class was intended to be more seaworthy than the US Navy's torpedo boats, the ship had a raised forecastle instead of the "turtleback" forecastle common in European designs. Design displacement was and full load, although all ships of the class were overweight. Four Thornycroft boilers fed steam at to triple expansion steam engines rated at driving two shafts for a design speed of . Four funnels were fitted. Armament consisted of two /50 caliber guns, five 6-pounder () guns and two torpedo tubes.
"Chauncey" was placed in reduced commission on 20 November 1902, then placed in reserve on 2 December 1902 and received full commission on 21 February 1903. Lieutenant Stanford Elwood Moses was placed in command and "Chauncey" reported to the Atlantic Fleet.
Pre-World War I.
"Chauncey" served with the Coast Squadron until 20 September 1903, when she was transferred to the Asiatic Fleet and left Key West for the Orient on 18 December. After sailing by way of the Suez Canal, she arrived at Cavite to join the force representing US interest in the Far East as it cruised in the Philippines during winters and off China during summers. Aside from the period of 3 December 1905 – 12 January 1907, when she was in reserve at Cavite, "Chauncey" continued this service until the entrance of America into World War I.
Sinking.
The destroyer sailed from Cavite on 1 August 1917 for convoy escort duty in the eastern Atlantic, based at St. Nazaire, France. On 19 November, while about west of Gibraltar on escort duty, "Chauncey" was rammed by the British merchantman SS "Rose" as both ships steamed in war-imposed darkness. At 03:17, "Chauncey" sank in of water, taking to their death 21 men including her captain, Lieutenant Commander Walter E. Reno, the namesake of the , and LTJG Charles F. Wedderburn, the namesake of the . Seventy survivors were picked up by "Rose", and carried to port.
"Chauncey" in literature.
The novel "Delilah" was written by a survivor of "Chauncey", Marcus Goodrich, and is a fictional account based on his experience serving aboard "Chauncey" as an enlisted man.


Voltammetry

Voltammetry is a category of electroanalytical methods used in analytical chemistry and various industrial processes. In voltammetry, information about an analyte is obtained by measuring the current as the potential is varied. The analytical data for a voltammetric experiment comes in the form of a voltammogram which plots the current produced by the analyte versus the potential of the working electrode.
Three electrode system.
Voltammetry experiments investigate the half-cell reactivity of an analyte. Voltammetry is the study of current as a function of applied potential.
These curves I = f(E) are called voltammograms.
The potential is varied arbitrarily either step by step or continuously, and the actual current value is measured as the dependent variable.
The opposite, i.e., amperometry, is also possible but not common.
The shape of the curves depends on the speed of potential variation (nature of driving force) and on whether the solution is stirred or quiescent (mass transfer).
Most experiments control the potential (volts) of an electrode in contact with the analyte while measuring the resulting current (amperes).
To conduct such an experiment one requires at least two electrodes. The working electrode, which makes contact with the analyte, must apply the desired potential in a controlled way and facilitate the transfer of charge to and from the analyte. A second electrode acts as the other half of the cell. This second electrode must have a known potential with which to gauge the potential of the working electrode; furthermore it must balance the charge added or removed by the working electrode. While this is a viable setup, it has a number of shortcomings. Most significantly, it is extremely difficult for an electrode to maintain a constant potential while passing current to counter redox events at the working electrode.
To solve this problem, the roles of supplying electrons and providing a reference potential are divided between two separate electrodes. The reference electrode is a half cell with a known reduction potential. Its only role is to act as reference in measuring and controlling the working electrode's potential and at no point does it pass any current. The auxiliary electrode passes all the current needed to balance the current observed at the working electrode. To achieve this current, the auxiliary will often swing to extreme potentials at the edges of the solvent window, where it oxidizes or reduces the solvent or supporting electrolyte. These electrodes, the working, reference, and auxiliary make up the modern three electrode system.
There are many systems which have more electrodes, but their design principles are generally the same as the three electrode system. For example, the rotating ring-disk electrode has two distinct and separate working electrodes, a disk and a ring, which can be used to scan or hold potentials independently of each other. Both of these electrodes are balanced by a single reference and auxiliary combination for an overall four electrode design. More complicated experiments may add working electrodes as required and at times reference or auxiliary electrodes.
In practice it can be important to have a working electrode with known dimensions and surface characteristics. As a result, it is common to clean and polish working electrodes regularly. The auxiliary electrode can be almost anything as long as it doesn't react with the bulk of the analyte solution and conducts well. It is (or was?) common to use mercury as working electrode e.g. DME and HMDE, and also as auxiliary, and the voltammetry method is then known as polarography. The reference is the most complex of the three electrodes; there are a variety of standards used and it is worth investigating elsewhere. For non-aqueous work, IUPAC recommends the use of the ferrocene/ferrocenium couple as an internal standard. In most voltammetry experiments, a bulk electrolyte (also known as a supporting electrolyte) is used to minimize solution resistance. It is possible to run an experiment without a bulk electrolyte, but the added resistance greatly reduces the accuracy of the results. With room temperature ionic liquids, the solvent can act as the electrolyte.
Theory.
Data analysis requires the consideration of kinetics in addition to thermodynamics, due to the temporal component of voltammetry. Idealized theoretical electrochemical thermodynamic relationships such as the Nernst equation are modeled without a time component. While these models are insufficient alone to describe the dynamic aspects of voltammetry, models like the Tafel equation and Butler–Volmer equation lay the groundwork for the modified voltammetry relationships that relate theory to observed results.
History.
The beginning of voltammetry was facilitated by the discovery of polarography in 1922 by the Nobel Prize–winning chemist Jaroslav Heyrovský. Early voltammetric techniques had many problems, limiting their viability for everyday use in analytical chemistry. In polarography, these problems included the fact that mercury is oxidized at a potential that is more positive than +0.2, which makes it harder to analyze the results for the analytes in the positive region of the potential. Another problem included the residual current obtained from the charging of the large capacitance of the electrode surface. When Heyrovsky first recorded the first dependence on the current flowing through the dropping mercury electrode on the applied potential in 1922, he took point-by-point measurements and he plotted a current-voltage curve. This was considered to be the first polarogram. In order to facilitate this process, he constructed what is now known as a polarograph with M. Shikata and, with enabled him to record photographically the same curve in a matter of hours. He gave recognition to the importance of potential and its control and also recognized the opportunities of measuring the limiting currents. He was also an important part of the introduction of dropping mercury electrode as a modern-day tool.
In 1942 Archie Hickling built the first three electrodes potentiostat, which was an advancement for the field of electrochemistry. He used this potentiostat to control the voltage of an electrode. In the meantime, the late 1940s, Kenneth Cole invented an electronic circuit which he called a voltage clamp. The voltage clamp was used to analyze the ionic conduction in nerves.
The 1960s and 1970s saw many advances in the theory, instrumentation, and the introduction of computer added and controlled systems. Modern polarographic and voltammetric methods on mercury electrodes came about in three sections.
The first section includes the development of the mercury electrodes. The following electrodes were produced: dropping mercury electrode, mercury steaming electrode, hanging mercury drop electrode, static mercury drop electrode, mercury film electrode, mercury amalgam electrodes, mercury microelectrodes, chemically modified mercury electrodes, controlled growth mercury electrodes, and contractible mercury drop electrodes.
There was also an advancement of the measuring techniques used. These measuring techniques include : classical DC polarography, oscillopolarography, Kaloussek's switcher, AC polarography, tast polarography, normal pulse polarography, differential pulse polarography, square-wave voltammetry, cyclic voltammetry, anodic stripping voltammetry, convolution techniques, and elimination methods.
Lastly, there was also an advancement of preconcentration techniques that produced an increased the sensitivity of the mercury electrodes. This came about through the development of anodic stripping voltammetry, cathodic stripping voltammetry and adsorptive stripping voltammetry.
These advancements improved sensitivity and created new analytical methods, which prompted the industry to respond with the production of cheaper potentiostat, electrodes, and cells that could be effectively used in routine analytical work.
Applications.
Voltammetric sensors.
A number of voltammetric systems are produced commercially for the determination of specific species that are of interest in industry and research. These devices are sometimes called electrodes but are, in fact, complete voltammetric cells and are better referred to as sensors. These sensors can be employed for the analysis of various organic and inorganic analytes in various matrices.
The oxygen electrode.
The determination of dissolved oxygen in a variety of aqueous environments, such as sea water, blood, sewage, effluents from chemical plants, and soils is of tremendous importance to industry, biomedical and environmental research, and clinical medicine. One of the most common and convenient methods for making such measurements is with the Clark oxygen sensor, which was patented by L.C. Clark, Jr. in 1956.


SendStation Systems

SendStation Systems is a manufacturer of computer and iPod accessories. The company was founded in 1997 in Frankfurt/Main, Germany by current President André Klein.
The name "SendStation" has its roots in a Macintosh-based turn-key video fax system the company created and sold between 1997 and 2000, and is a word play made up from "to send", "station" and "sensation". Back then (several years before public broadband internet access became available and affordable) "the" SendStation was the first system of its kind which allowed filmmakers, advertising agencies and industry clients to easily transfer full-screen-full-motion review copies of TV commercials within minutes around the globe, rather than using overnight couriers. Customers included companies like Audi, Wrigley and BBDO.
PocketDock.
In 2003 SendStation entered the hardware market, and became one of the initial five, officially authorized accessory manufacturers for the Apple iPod. Its first hardware product, the PocketDock FireWire adapter, allowed iPod owners to connect the device via the then freshly introduced 30-pin iPod dock connector to a standard 6-pin FireWire cable for sync & charge. It was one of the best-selling add-ons on the young market for iPod accessories.
As USB 2.0 became standard and iPods with video capabilities emerged, additional models followed. In order of release (most recent on top):
Other products include iPod car chargers, iPod dock extenders, earbud cases and multiple types of adapters for Mac & PC.


Thury thread

The Swiss-designed Thury screw thread (alternatively called the Filière Suisse, FS, screw thread) is a metric thread standard that was developed in the late nineteenth century for screws used in scientific and horological instruments. The thread is named after Marc Thury, an engineer and professor at the University of Geneva who contributed heavily to the standard's development.
History.
Development of the Thury thread began in 1876, when the Horological Section of Geneva Society of Arts appointed a committee to look into the requirements for a uniform thread standard for use in Horological arts in Switzerland. Professor Thury began his studies by collecting and measuring samples of screws made by nine independent screw and screw tackle manufacturers in Switzerland. The Thury thread form was developed in 1878, thirty-seven years after the British Standard Whitworth thread form was designed in England and fourteen years after the United States Standard thread was presented in the United States. However, unlike these two predecessors, the Thury thread was designed for small-diameter screws which were then produced with screw plates. This production technique mandated that the Thury thread form have rounded crests and roots. Thread forms with rounded or "radiused" crests and roots like the Thury and Whitworth thread generate smaller stress risers than those forms like the American National or ISO metric which have truncated roots and crests; in modern engineering this is particularly important factor when tapping holes in acrylic plastic, where a larger stress riser can lead to an earlier onset of crack formation. The Thury thread is unusual in having a comparatively small 47.5° thread flank angle, which was chosen to make fabrication easier and to achieve greater holding capacity than screws with larger flank angles. Screws in the Thury thread system are given nominal sizes, with the base size "0" being six millimeters in diameter and having a thread pitch of one millimeter. Sizes are proportional, so a size "1" is ten percent smaller in diameter that a size "0", while a size −1 is ten percent larger than a size "0". The Thury thread was believed to be the first thread form to solve the problem of creating a single system of screw dimensions applicable to all sizes. The relationship between the pitch "P" of a Thury screw and its diameter "D" is expressed by the equation . Another variable Thury standardized is the thread depth, which had until then been variable when cutting threads in different materials. The proliferation of the Thury standard was hindered when in 1882, the British Science Association produced a committee report on the consideration of a standard screw gauge, where they declined to accept the Thury thread but instead chose to use the Whitworth thread standard previously designed by committee member Joseph Whitworth, in part because the Whitworth form was historically successful and because the committee did not believe England was prepared to use a metric thread as its standard. However, the committee recognized the validity of many of the design aspects of the Thury thread, and a mere two years later published their specifications for the British Association (BA) thread. The BA committee made only slight modifications to the rounding radii of Thury thread and gave specifications rounded to the nearest thousandth of an inch.
Obsolescence.
Despite being a popular screw standards for nearly a century, both the Thury thread and the BA thread have largely been replaced by the ISO Metric thread form. Today the Thury thread is rare outside of antiques due to the relative abundance of other standard sized fasteners. For example, the British Association 0BA, the Löwenherz 6mm and ISOM6×1.0 fasteners have identical pitch and diameter to the Thury size 0 (however, they are not interchangeable because they differ in thread geometry).


Debye function

In mathematics, the family of Debye functions is defined by
The functions are named in honor of Peter Debye, who came across this function (with "n" = 3) in 1912 when he analytically computed the heat capacity of what is now called the Debye model.
Mathematical properties.
Relation to other functions.
The Debye functions are closely related to the polylogarithm.
Series Expansion.
They have the series expansion
where formula_3 is the n-th Bernoulli number.
Limiting values.
If formula_5 is the gamma function and formula_6 is the Riemann zeta function, then, for formula_7,
Derivative.
The derivative obeys the relation
where formula_10 is the Bernoulli function.
Applications in solid-state physics.
The Debye model.
The Debye model has a density of vibrational states
with the "Debye frequency" "ω"D.
Internal energy and heat capacity.
Inserting "g" into the internal energy
with the Bose–Einstein distribution
one obtains
The heat capacity is the derivative thereof.
Mean squared displacement.
The intensity of X-ray diffraction or neutron diffraction at wavenumber "q" is given by
the Debye-Waller factor or the Lamb-Mössbauer factor.
For isotropic systems it takes the form
In this expression, the mean squared displacement refers to just once Cartesian component
"ux" of the vector u that describes the displacement of atoms from their equilibrium positions.
Assuming harmonicity and developing into normal modes,
one obtains
Inserting the density of states from the Debye model, one obtains
From the above power series expansion of formula_19 follows that the mean square displacement at high temperatures is linear in temperature
The absence of formula_21 indicates that this is a classical result. Because formula_22 goes to zero for formula_23 it follows that for formula_24


Popover (GUI)

A Popover is a container-type graphical control element that hovers over its parent window and blocks any other interaction with until it is selected. It can contain various other graphical control element such as checkboxes, radio buttons or a list box. Like any container-type graphical control element, it is meant to group elements that belong together and is not meant to be extensive.
Popover graphical control element were introduced in GTK+ 3.12


Medusa Model 47

The Medusa Model 47 (or Medusa M47) is a revolver manufactured by Phillips & Rodgers Inc. of Huntsville, Texas, in the late 1990s. Based on the Smith & Wesson K frame, it is notable for being capable of chambering and firing approximately 25 different cartridges within the 9 mm caliber family, such as: .357 Magnum, .38 Special, .380 ACP, and 9×19mm Parabellum. While smaller diameter cartridges can be fired, accuracy suffers. The revolver was not a commercial success and the company that produced them ceased operations after just a few hundred units were made.
History.
The company that created the Medusa M47 is Phillips & Rodgers Inc., designed principally by Jonathan W. Philips Jr and Roger A. Hunziker, who produced a relatively small numbers of the hand gun in the late 1990s. Jonathan W. Phillips was a gunsmith and he also worked as a computer scientist for NASA. He was mainly responsible for the designing of the cylinder, extractor and ejector mechanism as well as the system that is used for positioning the cartridges. He applied for two patents on February 3, 1993, for the “Ejector and cartridge positioner for revolvers” and the "Ejector and cartridge positioner". He later filed for a patent that was called "Bore for weapons" on February 27, 1996, that outlines the rifling that the Medusa was going to use. Roger A. Hunziker designed the firing pin mechanism for the Medusa. He filed for a patent on August 1, 1995, for the "Firing pin mechanism". Phillips & Rodgers Inc. not only produced the Medusa M47 revolver but they also made several conversion cylinders for revolvers made by Smith & Wesson, Colt, and Ruger. Very few of these revolvers were actually produced.
Firing pin.
The firing pin mechanism was designed by Roger A. Hunziker. It is very similar to the system of Smith and Wesson revolvers. The firing pin is not a part of the hammer. Instead, it floats freely in the frame while under spring tension, so it does not rest against the primer of a cartridge. The hammer has a special feature: unless the trigger is squeezed, it will not be in contact with the firing pin. Instead, it rests a few millimeters back. There is also a transfer bar system between the hammer and firing pin. This allows the hammer to hit the firing pin only when the bar is up and the trigger is pulled.
Cylinder.
The design of the cylinder includes a spring-loaded tooth that extends into the chamber. When a rimmed cartridge is loaded, the tooth is pushed out of the way into the center of the cylinder by the cartridge and remains there until the round is extracted. The rim of the cartridge and the frame hold the round in place. When a rimless pistol cartridge is placed in the cylinder, there is no rim to stop the round from sliding down the chamber if it is not head spaced for that caliber. Thus, when the rimless cartridge is inserted, the tooth will be pushed down initially as the wall of the case slides in, but when the extraction groove near the base of the case is over the tooth, it will be pushed back out by spring pressure and catch the round. The tooth will keep the cartridge from sliding out the front of the cylinder, and the back of the frame will keep it from sliding out the back.
Construction.
The cylinder is made of mil spec 4330 modified vanadium steel. The Medusa M47 is based on the Smith & Wesson’s K frame, which is one of the most common revolver frame sizes, especially for revolvers that are chambered in the 9mm, .38, and .357 family of calibers. The revolver is able to be fired in both double and single action. Revolvers of this size have been very popular with police and military groups as well as the civilian market due to its reasonable weight and dimensions. In order to handle the immense pressure of the various rounds the pistol can fire the frame has to be very strong. It is constructed of 8620 steel which is hardened to 28 Rockwell. The barrel is composed of 4150 chromemoly steel. The barrel is also fluted, which may save some weight and speed up cooling of the barrel, but in practical terms these effects are minimal in a firearm so small, so the fluting is mostly for style.


Linda Garcia Cubero

Captain Linda Garcia Cubero (born 1958) is a former United States Air Force officer, of Mexican-American-Puerto Rican descent who in 1980 was a member of the first class of women to graduate from the United States Air Force Academy. She is the first Hispanic woman to graduate from any service academy.
Early years.
Cubero's father was a United States Air Force officer of Mexican-American descent and her mother of Puerto Rican ancestry. Her father was a very influential factor in her life and she decided to follow in his footsteps and apply for admission to the United States Air Force Academy. Despite the fact that she ranked 25/485 students in her high school class and that she was a member of the National Honor Society, her guidance counselors told her that she “wasn’t good enough” to make it into the USAFA.
United States Air Force Academy.
The United States Air Force Academy, located immediately north of Colorado Springs in El Paso County, Colorado, United States, is an institution for the undergraduate education of officers for the United States Air Force. Graduates of the four-year program receive a Bachelor of Science degree and most are commissioned as second lieutenants in the United States Air Force.
On October 7, 1975, President Gerald R. Ford signed legislation permitting women to enter the United States service academies. On June 26, 1976, Cubero was among 157 women that entered the Air Force Academy with the Class of 1980. In 1980, Cubero made history when she became a member of the first class of women to graduate from the United States Air Force Academy. There she earned her BS degree in Political Science and her free-fall parachute wings. Upon her graduation she was commissioned a Second Lieutenant.
Military service.
Cubero spent the next seven years in the Air Force serving as a command briefer, and on national-level task forces at The Pentagon. In 1982, Cubero was the recipient of a Joint Service Commendation Medal for her work with the Pentagon's intelligence task force assigned to the Falkland Island conflict. While serving as Special Assistant to the Deputy Secretary of Defense, Cubero supervised the development of a United States commemorative stamp designed by Hispanic Congressional Medal of Honor recipients to honor Hispanics in America's defense. The stamp was designed by the ten surviving Hispanic Congressional Medal of Honor recipients and unveiled on October 31, 1984. She continued to further her academic education and earned a master's degree in Systems Engineering from Virginia Tech.
Cubero also served as mentor to Hispanic Air Force cadets and was a volunteer worker in the wider Hispanic community. For her community service she was awarded the 1991 Hispanic Engineer National Achievement Pioneer Award.
Military decorations.
Among Garcia Cuberos military decorations are the following:
Badges:
Civilian life.
Cubero was honorably discharged from the Air Force with the rank of Captain in 1987. She went to work for General Electric Aerospace and by 1991 was working as the company's senior systems engineer. Subsequent to GE she worked as Director of Client Relations at Case Corporation in the purchasing group.
Cubero then went to work for the Global Purchasing support unit for EDS as the director of software purchasing, directing more than $500 million annually in spending and managing 60 software and technology professionals in four departments. In April 1999, Cubero was named Director of Hardware and Telecommunications Procurement, Global Purchasing support unit of EDS, responsible for managing about $3 billion in annual hardware and software spending. From 2004 to 2007 she was Client Director at Hewlett-Packard Managed Services and is now President of Falcon Cash Investments LLC.
Honors and recognitions.
Cubero was awarded the Women of Color Technology Award in 1998. In 1998, Cubero was also inducted into the National Hispanic Engineering Hall of Fame. In 2002, Hispanic Business magazine named her one of the “100 Most Influential Hispanics” in the United States.


Inagaki pistol

The Inagaki pistol is a semi-automatic pistol, designed by Iwakichi Inagaki, a retired employee from the Koishikawa Arsenal. Only 500 pistols were produced which were used both by Imperial Japanese Army and Imperial Japanese Navy (in small quantities). Production ceased in 1943 as the company focused on making pistol that could fire 8x22mm Nambu cartridge but they did not succeed. Only three pistols for 8mm Nambu were produced.
Design details.
The Inagaki is a simple blowback pistol with a very peculiar appearance. The weapon's safety lever is located on the left side of the weapon, although it is slightly odd in that the fire mode the weapon is in is determined by the marking not covered by the lever. When the weapon is in safe, the slide cannot be pulled back fully.
The slide is held in place only by the trigger guard, which makes disassembly of the weapon extremely simple; rotate the trigger guard and simply pull the slide and barrel off the weapon.


Martin Lowson

Professor Martin Lowson (5 January 1938 – 14 June 2013) was an aeronautical engineer. He held a number of senior academic appointments in UK and US universities, was a co-patentee of the BERP helicopter rotor system, and also made a significant contribution to the development of personal rapid transport systems.
Early life.
Martin Vincent Lowson was born in Totteridge, Hertfordshire, on 5 January 1938.
Education.
He attended The King's School in Worcester, after which he became an apprentice with Vickers-Armstrong. Lowson gained a PhD in 1963, after which he spent a year in the Institute of Sound & Vibration Research, where he worked on aero-acoustics.
Personal life.
Lowson married Ann Pennicutt in 1961. They had two children, Sarah and Jonathan. Lowson's interests included squash and bluegrass music.
Death.
Lowson died of a stroke on 14 June 2013, at the age of 75.


Berry-Wood A.O.W. Orchestrion

The Berry-Wood A.O.W. Orchestrion is a musical instrument that comprises a piano, 34 wood flute pipes, 34 wood violin pipes, a tambourine, a triangle, a cymbal, a wood block, castanets, a bass drum, a snare drum, a marimba, metal bells and a mandolin rail. It is classified as a player piano that operates via a paper roll and was built by the Berry-Wood piano company of Kansas. It features three stained glass panels and two decorative lamps.
The last functioning one of its kind in existence is housed in the DeBence Antique Music World Collection. It was once stated to be "particularly adapted for use in moving picture houses."


Macintosh Processor Upgrade Card

The generically named Macintosh Processor Upgrade Card (code named STP) is a central processing unit upgrade card sold by Apple Computer, designed for many Motorola 68040-powered Macintosh LC, Quadra and Performa models. The card contains a PowerPC 601 CPU and plugs into the 68040 CPU socket of the upgraded machine. The Processor upgrade card required the original CPU be plugged back into the card itself, and gave the machine the ability to run in its original 68040 configuration, or through the use of a software configuration utility allowed booting as a PowerPC 601 computer running at twice the original speed in MHz (50 MHz or 66 MHz) with 32 KB of L1 Cache, 256 KB of L2 Cache and a PowerPC Floating Point Unit available to software. The Macintosh Processor Upgrade requires and shipped with System 7.5.
Development of the card started in July 1993. The upgrade card was announced in January 1994 at the MacWorld Expo in San Francisco. Apple described the Macintosh Processor Upgrade Card as giving a performance increase of ""two to four times" for general purposes, or "up to 10 times"" for floating point intensive programs.
While the Macintosh Processor Upgrade did not plug into the LC Processor Direct Slot, due to power used and the space taken by the upgrade, LC PDS cards could not be fitted while the card was installed. This limited the usefulness of the Processor Upgrade Card, as internal ethernet, Apple IIe compatibility, video cards and other LC PDS expansion options must be removed.
DayStar Digital manufactured the Macintosh Processor Upgrade Card for Apple, sold the same card as their Daystar PowerCard 601-50/66 and also manufactured a Daystar PowerCard 601/100 which reached 100 MHz. After Daystar went out of business the 100 MHz model was manufactured and sold by Sonnet Technologies as their Sonnet Presto PPC 605.


.270 Winchester

The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54. The cartridge is the same length as the .280 Remington, both of which are longer than the .30-06 Springfield. The .270, .280, and .30-06 were all derived from the .30-03 parent case that came from the German 8x57 Mauser case which itself was based on the earlier 7x57 Mauser case. The .270 Winchester uses a .270 inch (6.86 mm) bore diameter and a .277 inch (7.04 mm) bullet diameter.
Description.
The .270 Winchester became a very popular cartridge due to the widespread praises of gunwriters like Townsend Whelen and Jack O'Connor who used the cartridge for 40 years and touted its merits in the pages of "Outdoor Life". It drives an bullet at approximately , later reduced to . The cartridge demonstrated high performance at the time of its introduction and was marketed as being suitable for big game shooting in the range, when that was considered long range hunting. With modern bullets and optics, it is easily a 1,000 yard cartridge. Two additional bullet weights were soon introduced: a hollow-point bullet for vermin shooting, and a bullet for deer, elk, and moose in big-game hunting. Renowned gunsmith Harold Fredd considers the 270 to be one of the most versatile cartridges for North American hunting and has recently started promoting it for small to medium sized plains games.
While not an immediate success, over the succeeding decades and especially in the post-World War II period, the .270 Winchester attained great popularity among gun owners, metallic silhouette rifle shooters and hunters, ranking it among the most popular and widely used cartridges worldwide. Internationally, firearms manufacturers now offer this chambering in all firearm varieties: bolt-actions, single-shots, lever-actions (such as the Browning BLR), pump-actions (such as the Remington 7600), autoloaders (such as the Remington 7400), and even a few double rifles.
Loads.
Cartridges are commonly available from sizes with loads being by far the most popular. Handloaders have a larger range of options with the availability of bullets in a number of weights from . Common bullet weight recommendations for shooting different game are as follows:
Recent introductions of low-drag bullets suited to the .270 Winchester such as the Nosler Accubond Long-Range, Hornady ELD-X and Matrix long range bullets are promoting renewed interest in the cartridge among long range hunters.
While it is true that a .270 Winchester case can be formed from a .30-06 Springfield case, the case length of a .30-06 is while the case length of a .270 is , within .5mm of a .30-03 Springfield. However, "The slight difference in length of reformed cases doesn't make any practical difference."


Vz. 24

The vz. 24 rifle is a bolt-action carbine designed and produced in Czechoslovakia from 1924 to 1942. It was developed from the German Mauser Gewehr 98 line, and features a very similar bolt design. The rifle was designed in Czechoslovakia shortly after World War I, to replace the Vz. 98/22, also a Czech-designed derivative of the Gewehr 98. The vz. 24 featured a barrel which was shorter and considered more handy than the Gewehr 98 barrel. The vz. 24 was chambered in 7.92×57mm Mauser like its predecessors.
Throughout the late 1920s and into the 1930s, Czechoslovakia exported hundreds of thousands of vz. 24 rifles to various countries across the globe, with variants chambered in the original 7.92×57mm Mauser, 7×57mm Mauser, and 7.65×53mm Argentine. These included contracts for several South American countries, most of which were 7 mm or 7.65 mm guns. Around 40,000 rifles were sent to Spanish Republican forces during the Spanish Civil War. Nearly 200,000 rifles were purchased by China, seeing action in the Second Sino-Japanese War, which became part of World War II. Iran purchased vz. 24 rifles, along with two other variants, through the late 1920s and 1930s, and later produced their own copies in the late 1940s.
Germany acquired hundreds of thousands of the rifles in 1939 when they occupied Czechoslovakia and pressed them into service under the designation "Gewehr 24(t)"; during the occupation, production of the rifles continued until 1942, when the factories were converted to the German-designed Karabiner 98k. During this period, several hundred thousand rifles were also built for the Romanian Army. Vz. 24 rifles saw extensive service during World War II in multiple theaters, predominantly with the German and Romanian armies on the Eastern Front. Lithuanian vz. 24s, which had been captured during the German invasion in 1941, were later seized by Soviet forces, who in turn used them to arm the Viet Cong during the Vietnam War in the 1960s.
Development and service with the Czechoslovak Army.
After World War I, the Austro-Hungarian Empire was dismantled; one of the new states to emerge from the ruins of the Habsburg Monarchy was Czechoslovakia. The new state received control of the Skoda factory in Brno, which was renamed the Brno Arms Works in November 1918. The following year, the factory began producing the first short rifles based on the German Gewehr 98 design, the "Mauser Jelená". At least 150 of the rifles were chambered in 7mm Mauser, with at least as many also chambered in 7.92×57mm Mauser. The original Gewehr 98 rifle featured a barrel that was long, which proved to be too long and cumbersome in the trench fighting of World War I. Nevertheless, Brno developed the long vz. 98/22 in 1922 from the basic Gewehr 98 design, with a long barrel, along with a vz. 98/22 Short Rifle variant, though it did not see significant production.
Starting in 1923, Brno decided to develop a rifle based on the German "Karabiner" 98AZ, a shortened version of the Gewehr 98 with a barrel. This resulted in the vz. 23, a rifle with a long barrel that was initially produced with parts cannibalized from other rifles. The design was further refined into the vz. 23A, which consisted of newly manufactured components. Further refinements produced the vz. 24, which entered production in 1924. That year, Brno Arms Works, which had been controlled by the Czechoslovak government, was privatized to encourage export sales.
The vz.24 became the primary rifle of the Czechoslovak Army before World War II. It resembled the German Karabiner 98k, which it predated by more than a decade. Unlike the K98k, the vz. 24 has a longer top handguard, and it retains a straight bolt handle. Between 1924 and 1938, Czechoslovakia manufactured more than 775,600 rifles, with the first rifles entering service in 1926. The final order was placed in July 1938, as tensions escalated with Nazi Germany over the Sudeten Germans. Following the German occupation of Czechoslovakia, production continued for the Slovak Republic (a Nazi client state). The exact number of rifles manufactured between 1938 and 1939 is unknown, but may be less than 10,000, based on serial numbers of surviving rifles.
Description.
The vz. 24 was a bolt action design based on the Mauser action, featuring a straight bolt handle. The rifle's barrel, which was long, featured 4-groove rifling with a right-hand twist. Overall, the rifle was long, and it weighed . The primary chambering was for 7.92×57mm Mauser, but export variants were also chambered for 7×57mm Mauser and 7.65×53mm Argentine. Ammunition was stored in a five-round, fixed, internal magazine that fit flush with the bottom of the stock, which was fed with stripper clips. The rifles were fitted with tangent rear sights that were graduated in increments, up to a maximum range of . The front sight blade was fitted with a protector to prevent it from being damaged.
The rifle's stock featured a semi-pistol grip and an upper hand guard that extended from the forward receiver ring to the forward barrel band. Sling swivels were placed on the bottom rear of the butt and the left side of the grip and on the rear barrel band. Grasping grooves were placed just forward of the recoil lug to aid in handling the rifle. A cleaning rod was stored in the stock under the barrel.
Export and foreign combat employment.
Many South American countries purchased the vz. 24 rifle in various calibers. Between 1928 and 1938, the Bolivian Army purchased 101,000 vz. 24 rifles, which were chambered in 7.65×53mm Argentine. These rifles were used against Paraguay during the Chaco War in the 1930s, and many of them were captured by the Paraguayan Army, which in turn used them against Bolivia. Colombia ordered 10,000 rifles between 1929 and 1937 and Venezuela purchased an unknown number of rifles in 1930; both countries' rifles were chambered in 7 mm. In 1932, Brazilian revolutionaries ordered 15,000 rifles, which were built with bent bolt handles. Peru ordered 5,000 rifles chambered in 7 mm in 1934, and Ecuador purchased 30,000 rifles in 7.92 mm in 1936. Guatemala and El Salvador ordered 4,000 and 300 7.92 mm rifles in 1937, respectively, and Nicaragua purchased 1,000 7 mm rifles that year. Also in 1937, Uruguay ordered 6,000 rifles in 7 mm, of which 2,000 were vz. 32/Modelo 1932 variants, which were essentially lightened vz. 24s.
Several European countries also acquired the rifle, all in the 7.92 mm caliber. The Lithuanian Army acquired the vz. 24 in the 1930s, and many of these rifles were captured by German forces during Operation Barbarossa before falling into the hands of the Soviet Army later in the war. Some of these rifles were then sent to Vietnam to arm the Viet Cong, and some were captured a third time by American forces during the Vietnam War. Yugoslavia purchased 40,000 rifles in 1926, all of which came from Czechoslovak Army stockpiles, and a further 10,000+ between 1928 and 1930. These rifles saw action during World War II during the German invasion of Yugoslavia in April 1941, as well as during the Partisans' insurgency against the German occupation. In 1935, Latvia traded surplus No. 1 Mk. III Lee–Enfield rifles for 15,000 vz. 24s; Brno Arms Works in turn sold the Lee–Enfields to Iraq. During World War II, Latvian resistance fighters employed the vz. 24s that had been ordered by the Latvian Army against the German occupation forces.
The vz. 24 also saw action in the Spanish Civil War by the Catalan Republican troops. About 40,000 vz. 24s were bought by the Soviet Union from Czechoslovakia to be sent to the Spanish Civil War. The vz. 24s were shipped from Murmansk on 1 March 1938, along with other material (T-26 tanks and 76 mm French field artillery). The French freighter , which carried all the material, managed to get the weapons to Bordeaux from where they were sent by land across the border to Catalonia. Despite arriving late in the war, the vz. 24 was used in Catalonia and the Mediterranean coast of the Iberian Peninsula and saw action in the Battle of the Ebro, where the vz. 24 showed good results despite the Francoist-Nationalist victory. After the defeat of the Second Spanish Republic, Generalissimo Francisco Franco kept the rifles that survived the battle until 1959, when they were sold to Interarms.
Starting in 1927, the Chinese Nationalist government began ordering rifles, and by 1937 had purchased 195,000 vz. 24s. They saw action during the Second Sino-Japanese War in the late 1930s and many of these rifles were captured by Japanese forces. They were then used to arm five infantry divisions stationed in China as well as the Collaborationist Chinese Army. After the war, Japan surrendered the rifles to China, which were then issued to Nationalist forces for use during the Chinese Civil War. China manufactured a copy of the vz. 24 that featured a shorter barrel and a side folding bayonet. Some of these rifles were captured by the People's Liberation Army and used in Korea. Japan also ordered 40,000 rifles for the Imperial Japanese Navy in 1938.
After World War II, rifles from Czechoslovakia were sent to Iraq. In 1967, the secessionist state of Biafra ordered various weapons from Czechoslovakia, including 1,860 vz. 24 rifles.
German G24(t).
After the occupation of Czechoslovakia in 1938, the Germans took existing stocks of the vz.24 into service under the designation Gewehr 24(t) ('t' being the national origin designator "tschechoslowakisch", the German word for "Czechoslovak"; such national origin designators were German practice for all foreign weapons taken into service). The G24(t) rifles manufactured after the German occupation were completed to a modified design to adhere to German standards. This included changes to the butt stock, with slots cut to fit German slings and the installation of the disc and hollow rod assembly that allowed soldiers to disassemble their bolts. Brno continued production of the rifle, which progressively gained some K98k features as stocks of pre-war components were used up. The original flat butt plate was replaced with the cupped butt plate of the K98k type, and the walnut stocks were replaced with easier to produce laminate versions.
In 1942, the production line at the Považská Bystrica plant was converted entirely to building K98k rifles and the main plant in Brno was similarly converted the following year. Over the course of 1941 and 1942, a total between 255,000 and 330,000 G24(t) rifles were built before production switched over to the K98ks. The G24(t) rifles did not receive the old Czechoslovak stampings, and instead only bore standard army proof marks and "Waffenamt" inspection codes.
Romanian vz. 24s.
In the late 1920s and early 1930s, the Romanian Army decided to adopt the vz. 24 rifle as its standard infantry rifle, though it had not acquired enough weapons to fully arm its troops by the time the country entered World War II in 1941. The first orders for the vz. 24 rifles were placed in 1938 after the German invasion. Romanian-contract vz. 24s have a two-letter prefix at the start of the serial number, the first letter being variable and the second "R" to designate Romania. Each initial letter denotes manufacturing blocks of 25,000 rifles. Romanian vz. 24s "AR", "BR", "CR" through "YR" represent different periods of manufacturing, though several blocks have not been reported, including "IR", "JR", "KR", "MR", "NR", "QR", "VR", and "ZR". Over the course of the contract, the Czechs manufactured between 400,000 and 750,000 Romanian vz. 24s. The first two years of production included royal crests for the King of Romania, though rifles built from 1940 onward do not feature crests, and many of the surviving early rifles have had their crests ground off. By mid-1943, 445,640 rifles had been received by the Romanian Army.
Romania was part of the Axis for much of World War II, from 1941 to 1944. Romanian vz. 24s saw action in Ukraine, Bessarabia, and in particularly heavy fighting during the Battle of Stalingrad. It was not until 1944, after significant defeats at the hands of the Soviet Red Army, that Romania joined the Allies.
Iranian Brno.
In 1929, Iran ordered 30,000 vz. 24 rifles chambered in 7.92 mm, all of which came from Czechoslovak Army stocks. A further order for 240,000 rifles was placed in 1930, though these were for the vz.98/29 variant with a longer barrel; another order for 30,000 vz. 98/29 "musketon" rifles was placed at the same time. Like several other countries' orders, the initial contract for the 30,000 vz. 24s came from Czechoslovak Army stocks, while the later orders for the vz. 98/29 variants were new production guns. The total order was not completed before Czechoslovakia was conquered by Germany. The "musketon" rifles were designated as the Model 30 carbine, and in the late 1940s, Czechoslovakia assisted the Iranians with setting up a factory to manufacture their own license-built copies, the Model 49 carbine.
The rifles, which were referred to as "Brnos" or "Bernos", after their city of manufacture, proved to be prized by Iran's various tribal groups, which frequently rebelled against the government of the Shah. After Reza Shah was deposed in 1941 by the Anglo-Soviet invasion of Iran, significant numbers of the rifles fell into the hands of tribal rebels, and they were used in tribal conflicts throughout the 1950s. During the Anglo-Soviet occupation, the Soviets seized and distributed 10,000 of the Brnos to Kurdish tribes in western Iran, which they also helped to train. The Kurdish force proved to be the basis of the Peshmerga.


Pop-up notification

The terms pop-up notification, toast, passive pop-up, snackbar, desktop notification, notification bubble, or simply notification all refer to a graphical control element that communicates certain events to the user without forcing them to react to this notification immediately, unlike conventional pop-up windows. Desktop notifications usually disappear automatically after a short amount of time. Often their content is then stored in some widget that allows the users to access past notifications at a more convenient time.
Support on different systems.
In Windows 2000, Microsoft introduced balloon help-like passive pop-up notifications, tied to the notification area of the task bar. Notifications get queued when user is away or screensaver is running, and get shown when the user resumes activity. They remain on screen for nine seconds while fading out if the user appears to ignore them. Microsoft also adopted similar notifications for its other software such as Windows Phone using the Microsoft Push Notification Service, Internet Explorer 7 and later, Microsoft Outlook, Microsoft Security Essentials, as well as Windows 8 and Windows 10 using the Windows Notification Service.
Desktop notifications are a proposed standard for freedesktop.org, but all the major desktop environments running on the X Window System already support this standard, making them typically available on Linux and other Unix-like systems. Google adopted the concepts of notification drawer and toast popup messages for user notifications as basic components of its Android operating system.
As of 10.8 Mountain Lion, OS X provides desktop notifications via Notification Center. Previous versions of OS X have no built-in desktop notification feature; however, Growl is a popular application that provides similar functionality and enjoys broad support from third-party software. iOS also includes Notification Center as of iOS 5.
Capabilities.
While passive pop-ups do not require any user interaction, some implementations still provide a way for the user to optionally interact with the pop-up. This is called "actions". For the Freedesktop specification, this is an optional feature that clients cannot rely on, and its use is discouraged by some design guidelines.
Android adds the ability to provide actions with Jelly Bean.
In Material Design.
Google's Material Design introduced the term "snackbar" to refer to a user-interface element displaying a temporary, closable notification:
"Snackbars inform users of a process that an app has performed or will perform. They appear temporarily, towards the bottom of the screen. They shouldn’t interrupt the user experience, and they don’t require user input to disappear."


Shuttle roller coaster

A shuttle roller coaster is any roller coaster that ultimately does not make a complete circuit, but rather reverses at some point throughout its course and traverses the same track backwards. These are sometimes referred to as boomerang roller coasters, due to the ubiquity of Vekoma's Boomerang coaster model.
Early history.
The first shuttle coasters were in fact the first roller coasters ever built. Inspired by the so-called "Russian Mountains," these wheeled cars built on tracks found popularity in the early 19th century in Paris.
In 1884, Switchback Railway opened at Coney Island, and consisted of a car that traveled on two tracks between two towers. It was the first roller coaster designed as an amusement ride in America. The next shuttle roller coaster to be built was Backety-Back Scenic Railway, built in 1909.
First launched shuttle coasters.
The first two launched shuttle coaster designs were introduced in 1977 by competitors Arrow Development and Anton Schwarzkopf. Arrow built and opened three that year including Black Widow (now defunct) at Six Flags New England, Screamin' Demon (also defunct) at Kings Island, and Zoomerang at Circus World (now located to Fun Spot Amusement Park & Zoo). Arrow's models used an electric motor to launch the train. Anton Schwarzkopf went with a different design using a dropped weight as a launch mechanism. This design was known as the Shuttle Loop. The first three built by that company were King Kobra at Kings Dominion (now located at Hopi Hari in Brazil), White Lightnin' at Carowinds (now located at Gold Reef City in South Africa), and Tidal Wave at California's Great America.
Schwarzkopf later upgraded its launch mechanism to a flywheel design. The first two roller coasters based on this new design were both released in 1978 - Montezooma's Revenge at Knott's Berry Farm and Greezed Lightnin' at Six Flags AstroWorld, currently in storage in Plainview, Texas for Cliff's Amusement Park in New Mexico. The first flywheel launched roller coaster that opened in Europe was Turbine at Walibi Wavre in 1982.
Vekoma's Boomerang.
In 1984 Vekoma debuted its "Boomerang" shuttle coaster, which features a lift hill rather than a launched train. In addition to the original Boomerang, Vekoma also designed the "Invertigo" and the "Giant Inverted Boomerang". As of 2018, 55 Boomerangs and its variants are currently in operation around the world.
Linear motor launched shuttle coasters.
In 1996 Premier Rides debuted the first coasters ever to use linear induction motors, and in 1997 opened at Six Flags Great Adventure, a pair of dueling launched shuttle coasters.
Intamin introduced its reverse freefall coaster in 1997. In these models, the train is accelerated out of the station along a long, level track using linear synchronous motors, rises straight up a vertical tower, then free falls back down to return to the station. Only two reverse freefall coasters were built: Tower of Terror II at Dreamworld, and at Six Flags Magic Mountain, both of which first broke the 300 foot and 400 foot barriers. Tower of Terror II, however, discontinued in 2019.
In 1998, Intamin introduced its first impulse coaster, Linear Gale at LaQua in Japan, which featured inverted trains traversing two vertical towers. In 2000, Intamin introduced Superman Ultimate Escape with a spiral tower and one vertical tower. Intamin introduced Wicked Twister in 2002, a variation with two spiral towers. With each pass through the station the train accelerates faster and travels further up the towers.


Lathen train collision

The Lathen train collision occurred on 22 September 2006 when a Transrapid magnetic levitation (or "maglev") train collided with a maintenance vehicle near Lathen, Germany, killing 23 people. It was the first fatal accident involving a maglev train.
The Transrapid.
The Transrapid 08 was still doing trial runs but would sometimes carry passengers along the test track to demonstrate the maglev technology. The Emsland test track runs from Lathen, near where the accident occurred, north to Dörpen, with a loop at each end and a depot side track near the southern loop. Speeds of up to 450 km/h (280 mph) are reached on the test track.
Maglev trains use powerful magnets to hover above the tracks.
The accident.
Every morning a wheeled, diesel-powered maintenance vehicle ran along the tracks to check them for debris. When its work was finished it would wait in front of the last switch. There were two workers on the maintenance vehicle. They radioed the line dispatcher for clearance to leave the track but did not get a response. They were unaware of a test run scheduled that morning half an hour earlier than usual. The test run was carrying visitors from associated companies, including employees at Transrapid, workers from a local nursing care company, and workers from local utility company RWE.
The maglev train was boarded according to usual routine. It left the station at 09:43 and firstly went for a brake test, then had to wait for clearance from the line dispatcher. The line dispatchers energized the tracks at 09:52 and one line dispatcher radioed the maglev train to proceed. No communication with the maintenance vehicle is recorded. The train rapidly accelerated to the 170 km/h that was common for the first test round before the 450 km/h on the subsequent test rounds.
The train started moving at 09:53, and 57seconds later emergency braking was recorded. Approximately half a second and 25metres later the maglev train hit the maintenance vehicle at a speed of 162km/h. The aerodynamic design of the Transrapid train caused it to dive under the 60-tonne maintenance vehicle, ripping off the roof of the maglev train. The wreckage continued for another 300 metres on the track before coming to a halt.
There were 23 fatalities and 11 injuries, 10 severe. The two-man crew of the maintenance vehicle were among the survivors as they were at the opposite end of the vehicle. Three survivors from the Transrapid were rescued by removing the bottom panel when they were heard knocking underneath. Two engineers sitting in the rear section of the maglev survived, and three other passengers were saved later by cutting through the remains of the maglev train. None escaped unscathed.
Emergency response.
Firefighters used turntable ladders and aerial platforms to reach the wreckage above ground level.
Immediate aftermath.
Immediately after the accident, German transport minister Wolfgang Tiefensee held an emergency meeting with representatives from Siemens AG and ThyssenKrupp, the two companies jointly responsible for the Transrapid. He commented afterwards that "major safety failings" were the clear cause of the accident, and that two key questions requiring answers were whether the Transrapid's safety measures were adequate, and whether they were applied on the test track. He also promised an independent inquiry.
German Chancellor Angela Merkel left a conference in Berlin in order to attend the scene. Wu Xiangming, head of the Shanghai maglev project, also visited the scene.
Investigation.
German authorities conducted an investigation into the accident. Rudolf Schwarz, head of operators at test track operator IABG, said, "This accident would not have been possible if all regulations were adhered to." According to IABG, the crew of the maintenance vehicle, which clears the test track of debris and dirt every morning, was supposed to radio the line dispatcher once the work was finished. German police therefore suspected human error as the likely cause of the accident. Prosecutors obtained and examined radio transcripts from the vehicles involved.
In May 2008, a court in Osnabrück concluded that the tragedy was caused by a chain of human errors, including the failure to set an electronic braking system that would have prevented the train from operating while maintenance work was being carried out. Two staff members were found guilty on 23 counts of manslaughter and 11 counts of causing negligent injury and were fined 24,000 and 20,000 euros respectively. The line dispatcher who radioed the clearance to the maglev train was unable to take part in the trial because of suicide fears. The trial of the two line dispatchers both resulted in convictions and prison sentences of one year and six months in one case, and one year in the other. Both sentences were suspended as the defendants were exceptionally remorseful, still mentally ill, and retired. They accepted the verdicts immediately.
Memorial.
One year after the accident, a memorial stone was installed at the crash site. A panel of steel, set into the stone, is stamped with 23 small crosses, one for each of the lives lost in the accident.


High Standard .22 Pistol

High Standard target pistols were manufactured in a variety of models in .22 Short and .22 Long Rifle chamberings for use in competition. One selling point was the similarity in grip angle and manual safety location to the M1911A1 series, a pistol common in service pistol competition. Manufactured from 1926 until 2018, High Standards are generally regarded as a classic .22 target pistol, and were common in national-level NRA Bullseye match shooting. Popular models include the High Standard Victor, Supermatic and Supermatic Trophy, and Olympic. Today, High Standards are popular among gun collectors.
A variant of the World War II-era High Standard target pistol was used as the basis for the High Standard HDM suppressed military model used by the Office of Strategic Services and later the US Military and Central Intelligence Agency.


Parts Manufacturer Approval

Parts Manufacturer Approval (PMA) is an approval granted by the United States Federal Aviation Administration (FAA) to a manufacturer of aircraft parts.
Approval.
It is generally illegal in the United States to install replacement or modification parts on a certificated aircraft without an airworthiness release such as a Supplemental Type Certificate (STC) or Parts Manufacturing Approval (PMA). There are a number of other methods of compliance, including parts manufactured to government or industry standards, parts manufactured under technical standard order authorization [TSO], owner-/operator-produced parts, experimental aircraft, field approvals, etc.
PMA-holding manufacturers are permitted to make replacement parts for aircraft, even though they are not the original manufacturer of the aircraft. The process is analogous to 'after-market' parts for automobiles, except that the United States aircraft parts production market remains tightly regulated by the FAA.
An applicant for a PMA applies for approval from the FAA. The FAA prioritizes its review of a new application based on its internal process called Project Prioritization.
The FAA Order covering the application for PMA is Order 8110.42 revision D. This document is worded as instructions to the FAA reviewing personnel. An accompanying Advisory Circular (AC) 21.303-4 is intended to address the applicant. 8110.42C addressed both the applicant and the reviewer. Per the order, application for a PMA can be made per the following ways: Identicality in which the applicant attempts to convince the FAA that the PMA part is identical to the OAH (Original Approval Holder) part. Identicality by Licensure is accomplished by providing evidence to the FAA that the applicant has licensed the part data from the OAH. This evidence is usually in the form of an Assist Letter provided to the applicant by the OAH. PMA may also be granted based upon prior approval of an STC . As an example: If an STC were granted to alter an existing aircraft design then that approval would also apply to the parts needed to make that modification. A PMA would be required, however, to manufacture the parts. The last method to obtain a PMA is Test & Computation. This approach consist of one or a combination of both of the following methods: General Analysis and Comparative Analysis. General analysis compares the proposed part to the functional requirements of that part when installed. Comparative Analysis compares the function of the proposed part to the OAH part. As an example: If a PMA application for flight control cables were to show that the PMA part exceeds the pull strength requirements of the aircraft system it is meant for, that is general analysis. To show that it exceeds that of the OAH part is comparative analysis. The modern trend is to use a variety of techniques in combination in order to obtain approval of complicated parts - relying on the techniques that are most accurate and best able to provide the proof of airworthiness desired. The cognizant regional FAA Aircraft Certification Office (ACO) determines if the applicant has shown compliance with all relevant airworthiness regulations and is thus entitled to design approval.
The second step in the application process is to apply to the FAA Manufacturing Inspection Divisional Office (MIDO) to obtain approval of the manufacturing quality assurance system (known as production approval). Production approval will be granted when the FAA is satisfied that the system will not permit parts to leave the system until the parts have been verified to meet the requirements of the approved design, and the system otherwise meets the requirements of the FAA quality system regulations. A Production Approval Holder (PAH) will typically already have satisfied this requirement before PMA application is made.
PMA applications based upon licensure or STC do not require ACO approval (since the data has already been approved) and can go straight to the MIDO.
History.
Under the Civil Air Regulations (CARs), the government had the authority to approve aircraft parts in a predecessor to the PMA rules. This authority was found in each of the sets of airworthiness standards published in the Civil Air Regulations. CAR 3.31, for example, permitted the Administrator to approve aircraft parts as early as 1947.
In 1952, the Civil Aeronautics Board adjusted the location of the parts production authority from the ".31" regulations to the ".18" regulations. For example, the CAR 3 authority for modification and replacement parts could be found in section 3.18 after 1952.
In 1955, the Civil Aeronautics Board separated the parts authority out of the airworthiness standards, and placed it in a more general location so that one standard would apply to replacement and modification parts for all different forms of aircraft.
In 1965 CAR 1.55 became Federal Aviation Regulation section 21.303.
The 1965 regulatory change also imposed specific obligations on the PMA holder related to the Fabrication Inspection System.
Amendment 21-38 of Part 21 was published May 26, 1972. This was the next rule change to affect PMAs. This rule eliminated the incorporation by reference of type certification requirements in favor of PMA-specific data submission requirements. This change established the separate process and separate requirements for data that must be submitted by an applicant for a PMA (prior to this there was no explicit distinction between the application data requirements for type certificated products and the data requirements for PMAed articles).
The aircraft parts aftermarket expanded greatly in the 1980s as airlines sought to reduce the costs of spares by finding alternative sources of parts. During this time period, though, many manufacturers failed to obtain PMA approvals from the FAA.
In the 1990s, the FAA engaged in an "Enhanced Enforcement" program that educated the industry about the importance of approval and as a consequence a huge number of parts were approved through formal FAA mechanisms. Under this program, companies that had previously manufactured aircraft parts without PMAs could apply for PMAs in order to bring their manufacturing operations into full compliance with the regulations. This movement brought an explosion of PMA parts to the marketplace.
2009 Rule Change.
The FAA published a significant revision to the U.S. manufacturing regulations on October 16, 2009. This new rule eliminates some of the legal distinctions between forms of production approval issued by the FAA, which should have the effect of further demonstrating the FAA's support of the quality systems implemented by PMA manufacturers. Specifically, instead of having a separate body of regulations for a PMA Fabrication Inspection System (FIS), as was the case in prior regulations, the PMA regulations now include a cross reference to the 14 C.F.R. § 21.137, which is the regulation defining the elements of a quality system for all production approval holders. In practice, all production approval holders were held to the same production quality standards before the rule change - this will now be more obvious in the FAA's regulations. Accomplishing this harmonization of standards was an important goal of the Modification and Replacement Parts Association (MARPA).
The new rule became effective April 16, 2011. The FAA's FAQ on Part 21 stated that PMA quality systems would be evaluated for compliance by the FAA during certificate management activity after the compliance date of the rule. Today, all FAA production approvals - whether for complete aircraft or for piece parts - rely on a common set of quality assurance system elements. E.g. 14 C.F.R. §§ 21.137 (quality system requirements for production certificates), 21.307 (requiring PMA holders to establish a quality system that meets the requirements of § 21.137), 21.607 (requiring TSOA holders to establish a quality system that meets the requirements of § 21.137).
Relationship to repair.
The FAA is also working on new policies concerning parts fabricated in the course of repair. This practice has historically been confused with PMA manufacturing, although the two are actually quite different practices supported by different FAA regulations. Today, FAA Advisory Circular 43.18 provides guidance for the fabrication of parts to be consumed purely during a maintenance operation, and additional guidance is expected to be released in the near future. One of the key features of FAC 43.18 is that it recommends implementation of a quality assurance system quite similar to the fabrication inspection systems that PMA manufacturers are required to have.
Industry association.
The trade association representing the PMA industry is the Modification and Replacement Parts Association (MARPA). MARPA works closely with the FAA and other agencies to promote PMA safety. MARPA maintains a website at http://www.pmaparts.org.
Developments Outside the United States.
The United States has Bilateral Aviation Safety Agreements (BASA) with most of its major trading partners, and the standard language of these BASAs requires the trading partner to treat FAA-PMA as an importable aircraft part that is airworthy and eligible for installation on aircraft registered in the importing jurisdiction. This process has been facilitated by the International Air Transport Association (IATA) which has published a book on accepting PMA parts.
Although the PMA industry began in the United States, several countries have begun promoting production of approved aircraft parts within their own borders. These jurisdictions include:
Other jurisdictions have established PMA regulations and are working with trading partners to achieve acceptance of their PMA industries, and thus should be expected to enter the PMA marketplace in the near future. For example, Japan has PMA regulations and has secured a bilateral agreement with the United States that authorizes the export of these parts to the United States as airworthy aircraft parts.


Pentacon Six mount

The Pentacon Six mount (commonly abbreviated to P6, or Б in Cyrillic) is a breech-lock bayonet lens mount originally used by several medium format single-lens reflex cameras from East Germany.
The lens mount was originally designed by Carl Zeiss Jena and Kamera Werkstätten (KW) for the Praktisix camera. KW later merged with several other companies to become VEB Pentacon; the Praktisix was improved and renamed the Pentacon Six. This camera was manufactured for a much longer time (almost 40 years) and exported widely; hence the lens mount became associated most with the Pentacon Six name, rather than the original Praktisix.
Variants.
Original.
The P6 mount is a simple bayonet mount. It has three short tabs on the lens; they are identical and correct orientation is assured by the placement of a post in front of the "top" tab. A pin holds the diaphragm open for fully open metering and focusing; this pin is released before the shutter is opened. The flange focal distance of mount is 74.1 mm.
The lens is inserted into the front of the camera and is held in place by a rotating collar.
This variant is seen on the Praktisix, Pentacon Six, Kiev 6C and Kiev 60.
Exakta 66.
The Exakta 66 added a TTL metered prism coupled to the shutter speed dial on the camera body and the aperture ring on the lens. It does this by projecting slightly over the front of the camera, allowing a rotating cam on the specially designed Schneider lenses to tell it what aperture setting was selected. And for lenses with a maximum aperture other than , a separate pin projects from the lens to the prism to tell it the maximum aperture.
Kiev 88 modifications.
The Kiev 88 is essentially a clone of the first Hasselblad - the 1600F/1000F. Like the Hasselblad, it has a threaded lens mount and Kiev-Arsenal manufactured its lens range in both the Pentacon Six mount (for the Kiev 60) and the Kiev 88 screw mount. However, there was interest in using Pentacon Six mount lenses from Carl Zeiss Jena and others on this camera (nicknamed the "Hasselbladski"). Thus various third parties worked to machine a P6-compatible lens mount into the Kiev 88. A major issue is the fact that the Kiev 88 has a greater flange focal distance than the Pentacon Six, requiring the lens to be recessed into the front of the modified Kiev 88. This causes physical clearance issues with some lenses, particularly the Exakta 66 lenses with a cam and possibly a pin for coupling the lens to a TTL prism.
A consequence of these early modifications is that the lens mount became twist-lock instead of breach-lock; the lens is inserted and turned.
Kiev 88СМ.
The Kiev 88СМ is a later version of the Kiev 88 manufactured with a P6 mount from the factory. Like the earlier Kiev 88 modifications, the lens is recessed in the front of the camera body. However it returns to the breach-lock origins of the mount. It has an "internal collar" that is turned by a tab accessible from the front of the camera.
Cameras.
From KW/Pentacon:
From Exakta GmbH:
From Kiev-Arsenal:
Adaptors are also available. They allow the use of P6 lenses on Mamiya 645, Pentax 645 and Contax 645 medium format cameras, Canon EF, Canon FD, Nikon F, Minolta AF, Minolta MD, Contax/Yashica, Pentax K, M42, and Leica R 35 mm cameras, as well as Lumix and Olympus micro 4/3 (m4/3), 4/3 system. There are also tilt and shift adaptors for most of the 35 mm lens mounts, making use of the larger imaging circle to allow control over perspective or focus.
Lenses.
Pentacon.
From East Germany, originally Meyer-Optik.
Carl Zeiss Jena.
From East Germany.
Schneider Kreuznach.
From West Germany, for the Exakta 66.
Kiev/Arsat.
From Ukraine.
Hartblei.
From Ukraine.
Arax.
From Ukraine.
Kilfitt.
From West Germany.
Zoomar.
From the United States.
Novoflex.
From West Germany.
Astro.
From West Germany.


Taurus PT22

The PT22 is a .22 LR semi-automatic pistol produced by Taurus and features an 8+1 round capacity magazine. The PT22 is often viewed as a Taurus copy of the Beretta 21 Bobcat due to having a similar "tip up" barrel. In fact this small pistol is very different in design and function from the Beretta. The PT22 may have either a cast aluminum or polymer frame, and a steel slide. It is one of an increasing variety of Taurus firearms manufactured in Florida, USA. It has a spur-less hammer, and a long but smooth double action only (DAO) trigger. The "tip up" barrel is useful in that the first round may be chambered directly into the barrel, and the operator does not have to "pull back" or "rack" the slide. Retracting the slide is difficult due to the heavy spring required in this blow-back action. The grip feel of the PT22 is "fat", and fills a normal-sized hand. This width may make the PT22 difficult for some smaller handed people to hold comfortably. The Taurus PT22 is only able to fire standard or high velocity cartridges; while hyper and ultra velocity cartridges will load and fire, they cannot be safely used in the PT22.
Taurus also sells a .25 ACP version called the PT25.


Triple Action Thunder

Triple Action Thunder is a Breech-loading, single shot handgun designed to fire the .50 BMG cartridge and developed by Triple Action LLC, an FFL based in Logan, Utah.


Magnetic dipole transition

The interaction of an electromagnetic wave with an electron bound in an atom or molecule can be described by time-dependent perturbation theory. Magnetic dipole transitions describe the dominant effect of the coupling to the magnetic part of the electromagnetic wave. They can be divided into two groups by the frequency at which they are observed: optical magnetic dipole transitions can occur at frequencies in the infrared, optical or ultraviolet between sublevels of two different electronic levels, while magnetic Resonance transitions can occur at microwave or radio frequencies between angular momentum sublevels within a single electronic level. The latter are called Electron Paramagnetic Resonance (EPR) transitions if they are associated with the electronic angular momentum of the atom or molecule and Nuclear Magnetic Resonance (NMR) transitions if they are associated with the nuclear angular momentum.
Theoretical description.
The Hamiltonian of an electron bound in an atom interacting with an electromagnetic field is given by the Pauli equation (the theoretical description follows ):
formula_1
The Hamiltonian can be split into a time independent and a time dependent part:
formula_2
with
formula_3
the atomic Hamiltonian and the interaction with the electromagnetic wave (time-dependent):
formula_4
Since the last term is quadratic in A it can be neglected for small fields.
The time-dependent part can be Taylor expanded in terms belonging to electric dipole(from the first term), magnetic dipole(from the second term), and higher order terms, such as electric quadropole and so on. The term belonging to the magnetic dipole transitions is:
formula_5
Selection rules.
The selection rules for allowed magnetic dipole transitions are:
1. formula_6 (J: total angular momentum quantum number)
2. formula_7 (formula_8: projection of the total angular momentum along a specified axis)
3. No parity change


Donald J. Leonard

Donald J. Leonard (born July 11, 1933) is an American electrical engineer and AT&T executive, who received the 1996 IEEE Simon Ramo Medal.
Biography.
Born in New York City, Leonard studied Electrical Engineering at the New York University in the 1950s, where he received his BEE in 1956 and his MEE in 1960.
After graduation Leonard started his career as researcher at the New York University Research Lab. After working for the New York Telephone Company some time, he joined AT&T Bell labs in 1956. Here he started his lifelong career at AT&T working on the further development of the Transmission System 1 (T-1), which were introduced by Bell Labs in 1962. He later supervised the development of a Pulse-code modulation for the Telstar. In 1963 he moved to Bell Labs in Merrimack Valley, where he was director of the Transmission Technology Laboratory from 1968 to 1970. In 1970 he moved to Indianapolis to direct the Telephone Laboratory. From 1977 to 1980 in Columbus he was executive director of Crossbar and Switching Operations, and from 1980 to 1982 at Western Electric he was Vice President of Corporate Engineering. In 1982 he returned to Bell labs, where he succeeded William O. Fleckenstein as Vice President, Switching Systems, and where in 1991 he was appointed Vice President, Quality, Technology, and Process Research. In 1994 he retired and got succeeded by Arun Netravali.
Leonard has been awarded an honorary doctorate from Midwest College of Engineering; the Hispanic Engineer National Achievement Award in 1992 by the Society of Hispanic Professional Engineers; and in 1996 the IEEE Simon Ramo Medal for his "engineering leadership in design and development of intelligent networks, digital electronic switching, transmission and signaling systems, and network databases." Pn In 1997 he was awarded an EMMY by the Academy of Television Arts and Sciences for his work on High Definition TV.


International Society of Biomechanics

The International Society of Biomechanics, commonly known as the ISB, is a society dedicated to promoting biomechanics in its various forms. It promotes the study of all areas of biomechanics at the international level, although special emphasis is given to the biomechanics of human movement. The Society encourages international contacts amongst scientists, promotes the dissemination of knowledge, and forms liaisons with national organizations. The Society's membership includes scientists from a variety of disciplines including anatomy, physiology, engineering (mechanical, industrial aerospace, etc.), orthopedics, rehabilitation medicine, sport science and medicine, ergonomics, electro-physiological kinesiology and others.
History.
The decision to establish the society was made at the 3rd International Seminar on Biomechanics held in Rome in 1971. This meeting was organized by the “Working Group on Biomechanics” which was part of the International Council of Sport and Physical Education, which itself was part of the United Nations Educational, Scientific, and Cultural Organization (UNESCO). At this meeting on September 29 it was voted to form the ISB at the next meeting. The 4th International Seminar on Biomechanics was held at Penn State University from August 26 until August 31, 1973. The constitution was voted on and approved on August 29. Two hundred and fifty of those present became charter members of the society.
Executive Council.
The ISB is governed by its Executive Council. This council is elected every two years, by ballot, and is composed of officers and council members that represent countries from throughout the world and scientific areas that span all facets of biomechanics. The council, which meets annually, provides leadership for the continued development of the Society. Many on-going activities are performed by Council appointed sub-committees. The council also publishes a quarterly newsletter, known as ISB NOW, to inform members of Society developments and future events.
Congresses.
The ISB was formed in 1973 and has held a conference every other year since then. The counting of the congress started with the 1st International Seminar on Biomechanics held in Zurich in 1967. The list of conferences and their geographical locations are given below.
Wartenweiler Memorial Lecture.
At each ISB Congress the Wartenweiler Memorial Lecture is presented. This lecture is named to honor Jurg Wartenweiler (1915-1976) who was the first president of the ISB. He organized The First International Seminar on Biomechanics in Zürich, Switzerland in 1967. This conference eventually morphed into the biennial ISB Congresses. He was a faculty member at the ETH Zürich. Typically this lecture has been the first academic presentation of the conference. The list of Wartenweiler Memorial Lecturers and their topics follow.
Muybridge Medal.
At the ISB Congress every two years, the ISB presents the Muybridge Award. This award is the most prestigious award of the Society and is awarded for career achievements in biomechanics. The award is named after Eadward Muybridge (1830-1904), who was one of the first to use cinematography for the study of human and animal movement. The list of Muybridge Award winners and their lecture topics follow,
Honorary Member.
The ISB has a number of categories of membership including: student, charter, full, and emeritus. The remaining category is that of honorary member, which is restricted to a few individuals whose work has made outstanding contributions to the development of Biomechanics. The honorary membership currently consists of 16 individuals. Unfortunately some of these members have died (Levan Chkhaidze, James Hay, Ernst Jokl, Chauncey Morehouse, John Paul, Jacquelin Perry, David Winter). The other honorary members and their current academic affiliations are,
Affiliated Groups.
Many other biomechanics groups and societies are affiliate members of the ISB. These groups include:
Technical and Working Groups.
The Society also supports technical and working groups, which are groups of individuals dedicated to enhancing knowledge of specialized areas within biomechanics. Currently active technical sections include,


IZh-56

The IZh-56 «Belka» (ИЖ-56 «Белка») is a Soviet double-barreled combination gun.
History.
IZh-56 was designed in 1956 and it was based on IZhK model.
Since 1961, a new varnish with improved characteristics has been used to protect the wooden parts of the gun.
In December 1964, the price of one standard IZh-56-3 was 45 rubles.
Design.
IZh-56 is an over and under shotgun, with one barrel above the other.
It has a birch or beech stock and fore-end.
All IZh-56s have iron sights and they can be equipped with scope base for PVS-1 (ПВС-1) optical sight.
The weight of PVS-1 scope without the scope base is 150 grams.


AirPort Extreme

The AirPort Extreme is a residential gateway combining the functions of a router, network switch, wireless access point and NAS as well as varied other functions, and one of Apple's former AirPort products. The latest model, the 6th generation, supports 802.11ac networking in addition to older standards. Versions of the same system with a built-in network-accessible hard drive are known as the AirPort Time Capsule.
Apple discontinued developing its lineup of wireless routers in 2016, but as of 2021 continues limited support of them in software and customer service.
History.
The name "AirPort Extreme" originally referred to any one of Apple's AirPort products that implemented the (then) newly introduced 802.11g Wi-Fi standard, differentiating it from earlier devices that ran the slower 802.11a and b standards. At that time the gateway part of this lineup was known as the AirPort Extreme Base Station. With the addition of the even faster Draft-N standards in early 2009 this naming was dropped, and from then on only the gateway has been known as the AirPort Extreme. Several minor upgrades followed, mostly to change antenna and power in the Wi-Fi. In 2013, a major upgrade added 802.11ac support and more internal antennas.
The AirPort Extreme has gone through three distinct physical forms. The earliest models were packaged similar to the original AirPort Base Station, in a round housing known as the "flying saucer". From 2007 to 2013 the Extreme was packaged in a rounded-rectangle white plastic housing, similar in layout and size to the Mac mini or earlier Apple TVs. The 2013 802.11ac model was re-packaged into a more vertical case, taller than it is square.
Discontinuation.
In approximately 2016, Apple disbanded the wireless router team that developed the AirPort Time Capsule and AirPort Extreme router. In 2018, Apple formally discontinued both products, exiting the router market. Bloomberg News noted that "Apple rarely discontinues product categories" and that its decision to leave the business was "a boon for other wireless router makers."
Features.
AirPort Disk.
The AirPort Disk feature allows users to plug a USB hard drive into the AirPort Extreme for use as a network-attached storage (NAS) device for Mac OS X and Microsoft Windows clients. Users may also connect a USB hub and printer. The performance of USB hard drives attached to an AirPort Extreme is slower than if the drive were connected directly to a computer. This is due to the processor speed on the AirPort Extreme. Depending on the setup and types of reads and writes, performance ranges from 0.5 to 17.5 MB/s for writing and 1.9 to 25.6 MB/s for reading. Performance for the same disk connected directly to a computer would be 6.6 to 31.6 MB/s for writing and 7.1 to 37.2 MB/s for reading. NTFS-formatted drives are not supported.
AirPort Extreme models by generation.
Original generation.
The original AirPort Extreme Base Station was so named because of its support for the 802.11g standard of the day, as well as for its ability to serve up to 50 Macs or PCs simultaneously. One feature found in most models of this generation was an internal 56K dial-up modem, allowing homes that lacked a broadband connection to enjoy wireless connectivity, albeit at dial-up speeds. It was the last generation to retain the "flying saucer" form factor. Later generations would adopt the short, rounded-square form factor that would be seen until 2013.
1st generation.
On January 9, 2007 the AirPort Extreme began shipping, with support for 802.11n draft specification, and built-in wireless print and storage server.
2nd generation.
On March 19, 2008, Apple released a firmware update for both models of the AirPort Extreme that, according to third-party reports, allowed AirPort Disks to be used in conjunction with Time Machine, similar to the functionality provided by AirPort Time Capsule.
3rd generation.
On March 3, 2009, Apple unveiled a new AirPort Extreme with simultaneous dual-band 802.11 Draft-N radios. This allowed full 802.11 Draft-N 2x2 communication in both 802.11 Draft-N bands at the same time.
4th generation.
On October 20, 2009, Apple unveiled an updated AirPort Extreme with antenna improvements.
5th generation.
On June 21, 2011, Apple unveiled an updated AirPort Extreme, referred to as "AirPort Extreme 802.11n (5th Generation)".
The detailed table of output power comparison between the "4th generation" model MC340LL/A and the "5th generation" model MD031LL/A can be seen below:
Note: A 3dB increase is equivalent to a doubling of power output.
6th generation.
On June 10, 2013, Apple unveiled an updated AirPort Extreme, referred to as "AirPort Extreme 802.11ac (6th Generation)". The 6th generation AirPort Extreme (and 5th generation AirPort Time Capsule) featured three-stream 802.11ac Wi-Fi technology with a maximum data rate of 1.3Gbit/s, which is nearly three times faster than 802.11n. Time Machine was now supported using an external USB hard drive connected to AirPort Extreme (802.11ac model only).
Discontinuation and support.
According to a Bloomberg report on November 21, 2016, "Apple Inc. has disbanded its division that develops wireless routers, another move to try to sharpen the company’s focus on consumer products that generate the bulk of its revenue, according to people familiar with the matter."
In an April 2018 statement to 9to5Mac, Apple announced the discontinuation of its AirPort line, effectively leaving the consumer router market. Apple continued supporting the AirPort Extreme.


Primary mirror

A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope.
Description.
The primary mirror of a reflecting telescope is a spherical or parabolic shaped disks of polished reflective metal (speculum metal up to the mid 19th century), or in later telescopes, glass or other material coated with a reflective layer. One of the first known reflecting telescopes, Newton's reflector of 1668, used a 3.3 cm polished metal primary mirror. The next major change was to use silver on glass rather than metal, in the 19th century such was with the Crossley reflector. This was changed to vacuum deposited aluminum on glass, used on the 200-inch Hale telescope.
Solid primary mirrors have to sustain their own weight and not deform under gravity, which limits the maximum size for a single piece primary mirror.
Segmented mirror configurations are used to get around the size limitation on single primary mirrors. For example, the Giant Magellan Telescope will have seven 8.4 meter primary mirrors, with the resolving power equivalent to a optical aperture.
Superlative primary mirrors.
The largest optical telescope in the world as of 2009 to use a non-segmented single-mirror as its primary mirror is the 8.2 m (26.9 ft) Subaru telescope of the National Astronomical Observatory of Japan, located in Mauna Kea Observatory on Hawaii since 1997; however, this is not the largest diameter single mirror in a telescope, the U.S./German/Italian Large Binocular Telescope has two 8.4 m (27.6 ft) mirrors (which can be used together for interferometric mode). Both of these are smaller than the 10 m segmented primary mirrors on the two Keck telescope. The Hubble Space Telescope has a 2.4 m (7 ft 10 in) primary mirror.
Radio and submillimeter telescopes use much larger dishes or antennae, which do not have to be made as precisely as the mirrors used in optical telescopes. The Arecibo Telescope used a 305 m dish, which was the world largest single-dish radio telescope fixed to the ground. The Green Bank Telescope has the world's largest steerable single radio dish with 100 m in diameter. There are larger radio arrays, composed of multiple dishes which have better image resolution but less sensitivity.


Galvanostat

A galvanostat (also known as amperostat) is a control and measuring device capable of keeping the current through an electrolytic cell in coulometric titrations constant, disregarding changes in the load itself.
Its main feature is its "nearly" ""infinite" (i.e. extremely high in respect to common loads) internal resistance.
The designation "galvanostat" is mainly used in electrochemistry: this device differs from common constant current sources by its ability to supply "and measure" a wide range of currents (from picoamperes to amperes) of both polarities.
The galvanostat responds to changes in the resistance of the cell by varying its output potential: as Ohm's law shows,
the variable system resistance and the controlled voltage are directly proportional, i.e.
where
thus, an increase of the load resistance implies an increase of the voltage the amperostat applies to the load.
Technical realization.
The simpler galvanostat consists of a high-voltage source producing a constant voltage "formula_6" with a resistor "formula_7" connected in series: in order to force an almost constant current through a load, this resistor shall be much higher than the load resistor formula_8. As a matter of fact, the current "formula_9" through the load is given by
and if formula_11»formula_8, the current "formula_9" is approximately determined by "formula_11" as follows
This simple realization requires rather high voltages (~100 V) to keep the load current constant with sufficient approximation for all practical purposes. Therefore, more complex versions of galvanostats, using electronic amplifiers with feedback and lower voltages, have been developed and produced. These instruments are capable to feed constant currents in the ranges from few picoamperes (pA) to several amperes (A); typical construction for use in the lower range of feed currents uses operational amplifiers.
Example of application.
Galvanostatic deposition techniques can be used for some thin film deposition applications where there is no need to control morphology of the thin film.


Stationary ergodic process

In probability theory, a stationary ergodic process is a stochastic process which exhibits both stationarity and ergodicity. In essence this implies that the random process will not change its statistical properties with time and that its statistical properties (such as the theoretical mean and variance of the process) can be deduced from a single, sufficiently long sample (realization) of the process.
Stationarity is the property of a random process which guarantees that its statistical properties, such as the mean value, its moments and variance, will not change over time. A stationary process is one whose probability distribution is the same at all times. For more information see stationary process.
Several sub-types of stationarity are defined: first-order, second-order, "n"th-order, wide-sense and strict-sense.
For details please see the reference above.
An ergodic process is one which conforms to the ergodic theorem. The theorem allows the time average of a conforming process to equal the ensemble average. In practice this means that statistical sampling can be performed at one instant across a group of identical processes or sampled over time on a single process with no change in the measured result.
A simple example of a violation of ergodicity is a measured process which is the superposition of two underlying processes,
each with its own statistical properties. Although the measured process may be stationary in the long term, it is not appropriate to consider the sampled distribution to be the reflection of a single (ergodic) process: The ensemble average is meaningless. Also see ergodic theory and ergodic process.


Treasure Hunters (Universal Studios Singapore)

Treasure Hunters is a vintage car attraction in Ancient Egypt area of Universal Studios Singapore. The attraction opened on March 18, 2010 with the rest of the park. The attraction is ideal for guests of all ages. Children under in height must be accompanied by a supervising companion. The ride takes guests on a slow tour of an abandoned excavation site. Animatronic animals within the attraction include some hippos, some vultures, many cobras, a cheetah, and some Nile crocodiles.