McCumber relation

The McCumber relation (or McCumber theory) is a relationship between the effective cross-sections of absorption and emission of light in the physics of solid-state lasers. It is named after Dean McCumber, who proposed the relationship in 1964.
Definition.
Let formula_1 be the effective absorption cross-section formula_2 be effective emission cross-sections at frequency formula_3, and let formula_4 be the effective temperature of the medium. The McCumber relation is
where formula_6
is thermal steady-state ratio of populations; frequency formula_7 is called "zero-line" frequency;
formula_8 is the Planck constant and
formula_9 is the Boltzmann constant. Note that the right-hand side of Equation (1) does not depend on formula_10.
Gain.
It is typical that the lasing properties of a medium are determined by the temperature and the population at the excited laser level, and are not sensitive to the method of excitation used to achieve it. In this case, the absorption cross-section
formula_1
and the emission cross-section
formula_2
at frequency formula_10 can be related to the lasers gain in such a way, that the gain at this frequency can be determined as follows:
D.E.McCumber had postulated these properties and found that the emission and absorption cross-sections are not independent; they are related with Equation (1).
Idealized atoms.
In the case of an idealized two-level atom the detailed balance for the emission and absorption which preserves the Planck formula for the black-body radiation leads to equality of cross-section of absorption and emission. In the solid-state lasers the splitting of each of laser levels leads to the broadening which greatly exceeds the natural spectral linewidth. In the case of an ideal two-level atom, the product of the linewidth and the lifetime is of order of unity, which obeys the Heisenberg uncertainty principle. In solid-state laser materials, the linewidth is several orders of magnitude larger so the spectra of emission and absorption are determined by distribution of excitation among sublevels rather than by the shape of the spectral line of each individual transition between sublevels. This distribution is determined by the effective temperature within each of laser levels. The McCumber hypothesis is that the distribution of excitation among sublevels is thermal. The effective temperature determines the spectra of emission and absorption ( The "effective temperature" is called a "temperature" by scientists even if the excited medium as whole is pretty far from the thermal state )
Deduction of the McCumber relation.
Consider the set of active centers (fig.1.). Assume fast transition between sublevels within each level, and slow transition between levels.
According to the McCumber hypothesis, the cross-sections formula_15 and formula_16 do not depend on the populations formula_17 and formula_18.
Therefore, we can deduce the relation, assuming the thermal state.
Let formula_19 be group velocity of light in the medium, the product formula_20 is spectral rate of
stimulated emission, and formula_21 is that of absorption; formula_22 is spectral rate of spontaneous emission. (Note that in this approximation, there is no such thing as a spontaneous absorption)
The balance of photons gives:
Which can be rewritten as
The thermal distribution of density of photons follows from blackbody radiation
Both (4) and (5) hold for all frequencies formula_10. For the case of idealized two-level active centers, formula_27, and formula_28, which leads to the relation between the spectral rate of spontaneous emission formula_29 and the emission cross-section formula_30. (We keep the term probability of emission for the quantity formula_31, which is probability of emission of a photon within small spectral interval formula_32 during a short time interval formula_33, assuming that at time formula_34 the atom is excited.) The relation (D2) is a fundamental property of spontaneous and stimulated emission, and perhaps the only way to prohibit a spontaneous break of the thermal equilibrium in the thermal state of excitations and photons.
For each site number formula_35, for each sublevel number formula_36, the partial spectral emission probability formula_37 can be expressed from consideration of idealized two-level atoms:
Neglecting the cooperative coherent effects, the emission is additive: for any concentration formula_39 of sites and for any partial population formula_40 of sublevels, the same proportionality between formula_41 and formula_42 holds for the effective cross-sections:
Then, the comparison of (D1) and (D2) gives the relation
This relation is equivalent of the McCumber relation (mc), if we define the zero-line frequency formula_45 as solution of equation
the subscript formula_4 indicates that the ratio of populations in evaluated in the thermal state. The zero-line frequency can be expressed as
Then (n1n2) becomes equivalent of the McCumber relation (mc).
No specific property of sublevels of active medium is required to keep the McCumber relation. It follows from the assumption about quick transfer of energy among excited laser levels and among lower laser levels. The McCumber relation (mc) has the same range of validity as the concept of the emission cross-section
itself.
Confirmation of the McCumber relation.
The McCumber relation is confirmed for various media.
In particular, relation (1) makes it possible to approximate two functions of frequency, emission and absorption cross sections, with single fit
Violation of the McCumber relation and perpetual motion.
In 2006 the strong violation of McCumber relation was observed for Yb:Gd2SiO5 and reported in 3 independent journals. Typical behavior of the cross-sections reported is shown in Fig.2 with thick curves. The emission cross-section is practically zero at wavelength
975 nm; this property makes Yb:Gd2SiO5 an excellent material for efficient solid-state lasers.
However, the property reported (thick curves) is not compatible with the second law of thermodynamics. With such a material, the perpetual motion device would be possible. It would be sufficient to fill a box with reflecting walls with Yb:Gd2SiO5 and allow it to exchange radiation with a black body through a spectrally-selective window which is transparent in vicinity of 975 nm and reflective at other wavelengths. Due to the lack of emissivity at 975 nm the medium should warm, breaking the thermal equilibrium.
On the base of the second Law of thermodynamics, the experimental results
 were refuted in 2007. With the McCumber theory, the correction was suggested for the effective emission cross section (black thin curve).
Then this correction was confirmed experimentally.


3494 Purple Mountain

3494 Purple Mountain, provisional designation , is a bright Vestian asteroid and a formerly lost minor planet from the inner regions of the asteroid belt, approximately in diameter. First observed in 1962, it was officially discovered on 7 December 1980, by Chinese astronomers at the Purple Mountain Observatory in Nanking, China, and later named in honor of the discovering observatory. The V-type asteroid has a rotation period of 5.9 hours.
Orbit and classification.
"Purple Mountain" is a core member of the Vesta family (), a giant asteroid family of typically bright V-type asteroids. Vestian asteroids have a composition akin to cumulate eucrites (HED meteorites) and are thought to have originated deep within 4 Vesta's crust, possibly from the Rheasilvia crater, a large impact crater on its southern hemisphere near the South pole, formed as a result of a subcatastrophic collision. Vesta is the main belt's second-largest and second-most-massive body after . Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (), a giant asteroid family and the largest family of stony asteroids in the main-belt.
"Purple Mountain" orbits the Sun in the inner asteroid belt at a distance of 2.0–2.7 AU once every 3 years and 7 months (1,315 days; semi-major axis of 2.35 AU). Its orbit has an eccentricity of 0.13 and an inclination of 6° with respect to the ecliptic. The body's observation arc begins with a precovery taken at Palomar Observatory on December 1951, or 29 years prior to its official discovery observation.
Lost asteroid.
"Purple Mountain" has been a lost minor planet. In November 1962, "Purple Mountain" was observed as at Goethe Link Observatory. A total of three additional observations were taken at Crimea–Nauchnij in 1969 and 1972, when it was designated as and , respectively, but was subsequently lost with no follow-up observations until its official discovery at Nanking in 1980.
Physical characteristics.
Based on the Moving Object Catalog (MOC) of the Sloan Digital Sky Survey, "Purple Mountain" is a common, stony S-type asteroid, with a sequential best-type taxonomy of SV. The "Collaborative Asteroid Lightcurve Link" (CALL) also assumes it to be a stony S-type.
In the SMASS-I classification by Xu, the asteroid is a V-type. This agrees with its measured high albedo "(see below)" often seen among the core members of the Vesta family. In 2013, a spectroscopic analysis showed it to have a composition very similar to the cumulate eucrite meteorites, which also suggests that the basaltic asteroid has originated from the crust of 4 Vesta.
Rotation period.
In June 2015, a rotational lightcurve of "Purple Mountain" was obtained from photometric observations by astronomers at Texas A&M University, using the SARA-telescopes of the "Southeastern Association for Research and Astronomy" consortium. The 0.9-meter SARA-North telescope is located at Kitt Peak National Observatory, Arizona, while the 0.6-meter SARA-South telescope is hosted at the Cerro Tololo Inter-American Observatory in Chile. Lightcurve analysis gave a rotation period of 5.857 hours with a brightness variation of 0.32 magnitude (). One month later, in July 2015, another period of 2.928 hours and an amplitude of 0.40 magnitude was measured at MIT's George R. Wallace Jr. Observatory (). The results are in good agreement, apart from the fact that the latter is an alternative, monomodal solution with half the period of the former. CALL adopts the longer, bimodal period solution as the better result in its Lightcurve Data Base, due to the lightcurve's distinct amplitude and the small phase angle of the first observation.
Diameter and albedo.
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, "Purple Mountain" measures 6.507 kilometers in diameter and its surface has an albedo of 0.347, while CALL assumes an albedo of 0.24 – derived from the body's classification into the Flora family – and consequently calculates a larger diameter of 7.82 kilometers based on an absolute magnitude of 12.7.
Naming.
This minor planet was named in honor of the Purple Mountain Observatory (PMO), an astronomical observatory located in Nanking (Nanjing), China. Built in 1934, the observatory is known for its astrometric observations and for its numerous discoveries of small Solar System bodies. It has played an important role in developing modern Chinese astronomy. The official naming citation was published by the Minor Planet Center on 29 November 1993 ().


Weights and Measures Act (Canada)

The Weights and Measures Act (R.S. 1985; ) (long title: "An Act respecting weights and measures") is a Canadian law governing the units of measurements used in Canada.
Originally passed in 1970 as part of the Government of Canada's plan for metrication of Canada from Imperial measures, it was stopped in 1985 and changes were made to the act. The Metric Commission was created by the act and abolished in 1985.
The act sets forth the regulation of measurements and the commerce conducted using measuring devices. The act provides that the International System of measurement be used with what the act calls "Customary units used with the international system" such as hour, minutes, litres, hectares, tonne or metric ton.
In addition, the act allows usage of what it labels as "Canadian units" (the imperial system), such as miles, inches, imperial gallons, and acres. In SCHEDULE III - section 5, the act also provides for the usage of certain French units in what it labels as "UNITS OF MEASUREMENT TO DESCRIBE CERTAIN LAND IN QUEBEC". The five permitted old French units are the foot (the French foot of 12.789 inches), arpent (for both length and area), and perch (for both length and area).


Sumatra Trench

The Sumatra Trench is a part of the Sunda Trench or Java Trench. The Sunda subduction zone (called also: the Sumatra-Andaman subduction zone) is located in the east part of Indian Ocean, and is about from the southwest coast of Sumatra and Java islands. It extends over long, starting from Myanmar in the northwest and ending at Sumba Island in the southeast.
Geological settings.
The Java trench was generated by the oblique subduction of the Indo-Australian Plate into the Sunda plate at a rate of 61mm/y (in the south) and 51mm/y (in the north). The oceanic crust being subducted via this accretionary margin has variable ages (40 to 100 Ma) and structure along the trench. There is also research showing that arc parallel dextral strike-slip fault systems (i.e. the Great Sumatra fault) developed on the landward side of the Sunda forearc to absorb part of the dextral motions associated with the oblique plate convergence. After the disastrous 2004 Sumatran tsunami, more and more researchers begin to study this area. The trench slope is now being considered as a result of folds and faults in the area which were originated from the local seafloor deformation.
Seismic profiles at Sumatra Trench shows that, the down-going Indo-Australian plate has its slip vectors rotate to a NE direction. This indicates that the plate motion is dominated by the dextral shear inside the Indo-Australian Plate in the order of 3.6–4.9 cm/yr. Transpressive deformation of the subducting plate edge is the primary to absorb the shear force. At the southeast section of this area, the Sumatra fault zone bends towards south and merges into the extensional south striking fault system of the Sumatra trait. The Sumatra Trench near the northwestern and western parts of Sumatra are defined as a high hazard region where 6.0 and 7.0 Mw magnitude earthquakes can generate quite often, i.e. every 6–12 and 10–30 years, respectively.
The Sumatra Fault Zone (SFZ) is the most worth noting area on the Eurasian plate near the Sumatra Trench. Within the Sumatra Fault Zone lies the majority of the right-lateral stress from the relative motion between the Indo-Australian and Eurasian plates. The Sumatra Fault Zone meets the south trending extensional faulting system in Sunda Strait in Semangka. The fault zone can generate submarine pull-apart grabens.
Structure.
In the convergent margins where accretion plays an important role, prism width varies from 40 km to 350 km. The width at Sumatra trench is controlled by sediment input and accretion rate and history. One distinguishing feature of the Sumatra subduction zone is that it has a relatively 120–140 km accretionary prism and a deep forearc basin (so does the rest of the whole Java subduction zone). However it does vary along the trench. The prism is broad and has a relatively shallow surface slope in the northern part, becomes steep and narrow at the central part, then becomes steep and narrow in the southern area.
Accretionary prism.
The inner part of the prism forms a NW-SE arc ridge offshore Sumatra with Enggano Islands being its highest point. This arc ridge has the widths of 30–60 km and is made up of 5 to 6 southward thrusting imbricated flakes. The flakes can be easily noticed due to their distinctive characteristics such as morphology, synclines, turn-overs and size. A distinctive strip-thrust fold locates on the western boundary of the accretionary wedge occurs on south of Enggano Island. A deformed and relatively thin (0.3–0.8 TWT) sedimentary layer covers almost all the subsurface areas. The scarce but still existing missing of part of the arc ridge offshore is result from extensional tectonic activities together with compression partitioning.
Forearc basin.
All the basement can be easily realized based on strong multiple reflections from the seafloor except some places in the north part because of the existing of some down faulted continental blocks. There is a main normal fault correlated along the Sumatra region. Offshore Sumatra continental basement underlies the seaward propagating wedges. The basin in southern Sumatra is greatly influenced by anticlines and fault zones.
North Sumatra region.
The North Sumatra region is defined here as the segment between 2.4–6°N. Accretionary wedges and forearcs here are very broad. A steep toe also presents. Average accretionary wedge has a width about 155–163 km, and the forearc basin has about 100–140 km thickness. Superficial average slope is about 1.2–1.3° while the outer part (about 50 km) becomes extremely steeper (3.3–3.9°) compare to the rest. Landward vergence of thrust folds, primarily frontal fold vergence is the most ubiquitous tectonic event happens at the prism bottom. Several landward vergences have been transformed into seaward. Seaward vergence is common further into the prism while landward vergent structures are more rare. The unusual structure here results in not only a strong wedge interior, but also tendency of a duplex deformation.
Central Sumatra region.
The central region is from 3°S–2°N in the area near Simeulue island (2–2.5°N). The prism narrows greatly with the increasing of average surface slope. This is an indication of the existence of a transition zone between North and Central Sumatra regions. In the Central Sumatra region, a wide basement high, which has connections with the N-S trending fracture zone, is being subducted and causing the generation of variations in sediment thickness across the oceanic plate. The transition zone in the Central Sumatra region is defined as 2–2.5°N, based on the abruptly changes of structure, morphology and sediment changes. The structure and morphology begin to change at 2.4°N but the sediment thickness remains unchanged until 2°N. Prism width decreases from 150 km to 100 km over less than 100 km strike during the surface slope increases from 1° to 3°. This region has variable oceanic plate topography, sediment component and seafloor hardness. Because as it goes further and further from the Bengal Fan source, the ridge and basement structure together with sediment thickness keep changing. Changes in prism morphology southward are gradual and an alternative boundary can be determined at 4–5°S, at this area the seafloor hardness is decreasing and deformation front heads towards sea.
South Sumatra region.
The South Sumatra region is from 5–7°S. The prism broaden from 115 kn to 140 km in this area, where surface slope decreases to 2°. This transition is gradual from north to south thanks to the decreasing effects of basement topography. From south of Enggano Island (6°S), the prism can be divided into 3 regions along the strike, each of it has shallower landward slope than the next. This is consistent with the presence of the slope break at about 30 km. A similar prism with mixed vergence of prism toe thrust folds exists north of the Enggano island.
Sediment.
Sediment thickness.
The trench sediment thickness is primarily based on three factors: distance from the source, oceanic plate topography and the ability of basement barriers to stop sediment from transporting southward.
It is widely agreed that the sediments on the trench come from the Bengal Fan and Nicobar Fan. So the decreasing water depth from south to north indicates the distance from the source. So the sediment thickness can reflect the proximity of the region to the source in general. But there are some exceptions exist in nearby regions like Andaman where the eastern flank of the Ninety East Ridge can result in the reducing of the sediment thickness. The thickness is minimum at South Sumatra (1–2 km) and maximum at north Sumatra. The thickest sediment at north Sumatra can compare with the Makran Trench, which has the thickest sediment on Earth (7.5 km).
Sediment thickness along the Sumatra Trench varies significantly, which is the result of fracture zones and fossil ridges' influence on basement topography. The thickness is a function of oceanic basement topography in some extent and this feature is extremely distinctive in the part between Simeulue and Siberut Islands (Central Sumatra region 2°N to 3°S) along the trench. This sediment thickness variation then leads to thin and variable sediment cover in many places, sometimes hinders the sediment transportation along the Sumatra Trench. Generally the prism width increases with sediment input, there are a few anomalies in the central Sumatra region due to basement topography, i.e., the current sediment thickness is larger than the long-term average.
There are also many correlations between convergence and thickness. Particular in some places near north Sumatra, where prism toe vergence accompanies with very thick sedimentation. On the other hand, the narrowing and steepening of the prism and toe vergence together often correlate with reduced thickness on Central Sumatra region. This is where structural convergence and distance from the source function together to determine the sediment thickness. Usually when thickness is 3–4 km thick, landward vergence exists; seaward vergence is dominant when it's 1–1.5 km thick; and if thickness is between these two segments, mixed vergence can be observed. As an example of mixed and variable convergence, Central Sumatra region (sediment thickness is ~1–3 km) may has basement topography as a more dominant factor.
Sediment properties.
Sediment properties related not only with sediment rate or source, but also with depth (thickness) related thermal diagenetic and metamorphic reactions, oceanic basement processes. Other factors such as prism structure and morphology also influence sediment properties.
In the north Sumatra region, where sediment is thick and prism wedge is wide, the dip is always shallow and landward vergence in toe is ubiquitous. it can generate high temperatures to dehydrate clays and strengthening the section. In south Sumatra region, topography and basement thickness is also very variable and overlaps with the region where prism is narrow and steep. Overall, the variations of material properties of sediments in Sumatra Trench is a result of structural variations along the trench.


Central Universities Common Entrance Test

The Central Universities Common Entrance Test (CUCET) is an all-India test is being organized for admission to various Integrated/Under-Graduate, Post Graduate and Research Programmes in several Central Universities and State Universities of India. From its inception in 2010, the CUCET is conducted/coordinated by the Central University of Rajasthan.
History.
CUCET was first conducted to admission for seven central universities for 1,500 seats in 41 undergraduate, postgraduate and integrated courses from 2010. The application form was filled up through "CUCET-2010" which held on 19 and 20 June 2010 in about 30 examination centres spread across the country.
Exam pattern and structure.
All Question Papers are MCQ based organized into different parts.
Negative marking.
For UI & PG Programmes, negative marking scheme is followed with a deduction of 0.25 marks for each wrong answer. However, the negative marking is not followed for research programmes.
Duration.
2 Hours
Organizing body.
Central University of Rajasthan is coordinating the CUCET in 2020.
Application fees.
Only online applications are accepted for CUCET-2020 and application fees for various categories are listed below.
Participating universities.
Admission in the following universities is done through CUCET.


Despite the Night

Despite the Night (original title: Malgré la nuit) is a 2015 French-Canadian experimental film directed by Philippe Grandrieux.
Release.
The film premiered at the Festival du nouveau cinéma in October 2015. It was screened at the AFI Fest in November 2016.


Italian units of measurement

A variety of units of measurement were used in the various independent Italian states and Italian dependencies of foreign empires up to the unification of Italy in the 19th century. The units to measure length, volume, mass, etc., could differ widely between countries or between towns in a country (e.g. Rome and Ancona), but usually not between a country and its capital.
The Kingdom of Sardinia included the island of Sardinia and the continental areas of Piedmont (with the capital Turin) and Liguria (with Genoa). The Kingdom of Naples included the island of Sicily (with Palermo). The Kingdom of Lombardy–Venetia was part of the Austrian Empire, which also shared ruling family with Modena, Parma and Tuscany (capital Florence). The Papal States included the areas of Latium (with the capital Rome), Umbria, Romagna (with Bologna) and the Marches (with Ancona).
Milan adopted the metric system in 1803, during the Napoleonic wars, albeit reusing names of older units. After the Congress of Vienna, the various Italian states reverted to their original systems of measurements.
In 1845 Sardinia passed legislation to introduce the metric system within five years. In 1859 Lombardy (but not Venetia) was annexed. In 1860 Parma, Modena, Tuscany, Umbria, Romagna and the Marches, and the Two Sicilies (Naples) were assimilated into Sardinia and under the "Law 132 of 28 July 28, 1861" the metric system became the official system of measurement throughout the (this year) Italian kingdom. The last to be incorporated were Venetia (1866), and the rest of the Papal States (1870).
For historical Roman measurements see Ancient Roman units of measurement. The following is a list of units before the adoption of the metric system as well as local names for metric-based units.
Over time a lot of unit names were reused for metric units, adding an unnecessary obstacle to the system change. These units are marked with €. They are also placed after the traditional.
Length.
Units varied from one province or city to another. In the north the atomo was the smallest unit.
Dedicated use:  # architect's   † commercial   ‡ mercer's
Mass.
One libbra (pound) differed between 307 and 398 g.
Several countries used both a light and a heavy pound.
Dedicated use:  # gold   ∆ silver   § jewels   † apothecaries'   ‡ silk   @ spices, drugs and pigments   ¥ commercial   ¢ oil     ship cargoes: ∑ grain   flour etc   © salt
Area.
Dedicated use:  # architect's
Volume (dry).
Dry and wet capacity (volume) were usually two separate systems, but a few units were universally handled, mostly in countries that had had experience with the metric system. (One of the sources do not state what subsystem they are handling).
Dedicated use:  # firewood   † grain   ‡ salt   ∆ oats and legumes   ∑ coal
Volume (liquids).
There are also a unit cantara: no specifics.
Dedicated use:  # wine   † spirits   ‡ oil


NYSE Chicago

NYSE Chicago, formerly known as the Chicago Stock Exchange (CHX), is a stock exchange in Chicago, Illinois, US. The exchange is a national securities exchange and self-regulatory organization, which operates under the oversight of the U.S. Securities and Exchange Commission (SEC). Intercontinental Exchange (ICE) acquired CHX in July 2018 and the exchange rebranded as NYSE Chicago in February 2019.
History.
1882–1900.
The Chicago Stock Exchange was founded in a formal meeting on March 21, 1882. At this time, Charles Henrotin was elected the chairman and president. In April that year, a lease was taken out at 115 Dearborn Street for the location of the exchange and during that year 750 memberships were sold. On May 15, 1882, the Chicago Stock Exchange officially became public and opened its offices, with Henrotin being the first to promote it along with some business associates.
In 1894, the Chicago Stock Exchange moved its trading floor to the old Chicago Stock Exchange building, designed by the firm of Adler & Sullivan, which was located at corner of Washington and LaSalle streets. The old Chicago Stock Exchange building was demolished in 1972, but the original trading floor and main entrance can now be found at the Art Institute of Chicago. The exchange began to flourish significantly in the late 1880s, with the rate of transactions of stocks and bonds increasing and earning them big profits.
1901–2000.
In July 1914, the Exchange closed as a result of World War I, and remained closed until December 11. In October 1915, the basis of quoting and trading in stocks changed from percent to par value to dollars. On April 26, 1920, the Chicago Stock Exchange Stock Clearing Corporation was established. On October 29, 1929, the stock market crashed, resulting in a very difficult time period for the Chicago Stock Exchange, and the stock market in general.
In 1949, the CHX merged with the exchanges of St. Louis, Cleveland and Minneapolis/St. Paul to form the Midwest Stock Exchange, which kept its headquarters in Chicago. In 1959, the New Orleans Stock Exchange became part of the Midwest Stock Exchange, and in the early 1960s the Midwest Stock Exchange Service Corporation was established to provide centralized accounting for member firms.
In April 1978, the Chicago Stock Exchange launched an Intermarket Trading System (ITS), a system that allowed orders to be sent from one exchange to another to ensure that customers received the best execution available. In the 1980s, the Chicago Stock Exchange made several technological advancements to improve trading. In 1982, the CHX launched the MAX system, which allowed CHX to be one of the first stock exchanges to provide fully automated order execution. In 1987, the CHX implemented programs to trade Nasdaq securities.
In the 1990s, the Exchange had a rebirth, and in 1993 changed its name back to the Chicago Stock Exchange, reflecting its roots and identity within the Chicago financial community. In 1997 the Chicago Stock Exchange began trading exchange-traded funds (ETFs).
2001–present.
At the beginning of the new millennium, several major changes occurred. In 2005, the SEC approved a change of the ownership structure of the CHX from a not-for-profit, member-owned company to a for-profit, stockholder-owned corporation. The CHX now operates as a direct and wholly owned subsidiary of CHX Holdings, Inc., a Delaware corporation. Later in 2005, the CHX implemented the Electronic Book trading platform; the predecessor technology of the New Trading Model's Matching System. In 2006, the Exchange announced regulatory and shareholder approval of an investment in CHX by Bank of America Corporation, Bear Stearns (acquired by JP Morgan Chase in 2008), E*TRADE FINANCIAL Corporation, and Goldman, Sachs & Co. In the same year, the CHX announced that it had completed the migration to the New Trading Model platform (the CHX Matching System).
The National Stock Exchange ceased trading operations on May 30, 2014, bringing the number of active stock exchanges in the United States to 11. Wrote "Bloomberg", that left "just one public exchange, Chicago Stock Exchange Inc., that isn't owned Bats, Nasdaq OMX Group or IntercontinentalExchange Group Inc."
On February 5, 2016, Chongqing Casin Enterprise Group, a Chinese-led investment group, entered into a definitive agreement to acquire CHX Holdings, Inc., the parent corporation of the Chicago Stock Exchange, for an undisclosed amount, which is subject to regulatory approvals. The privately held Casin Group was founded in 1997. A minority ownership position is held by Bank of America, E-Trade, Goldman Sachs and JPMorgan Chase. The acquisition is valued to be less than $100 million. However, the deal was questioned by then-candidate Donald Trump during his 2016 presidential campaign. Moreover, Congressman Robert Pittenger urged the United States Department of the Treasury to look into the Casin Group's background. By August 2017, the deal was still pending, with the U.S. Securities and Exchange Commission expressing reservations. The sale was blocked by the government in February 2018.
The New York Stock Exchange's parent company, Intercontinental Exchange Inc., agreed to acquire the 136-year-old market for an undisclosed amount. CHX will continue to operate as a registered national securities exchange till the end of 2019 when CHX will cease to exist.
Trading on the CHX.
The CHX Matching System was designed for full electronic trade matching. Publicly traded companies do not need to be listed on the CHX to be traded at CHX; SEC rules allow the CHX to trade stocks listed on other exchanges.
In 2016, CHX rolled out its on-demand auction product, CHX SNAP (Sub-second Non-displayed Auction Process), which received regulatory approval from the Securities and Exchange Commission in October 2015 and a thorough review from the Federal Reserve Bank of Chicago. CHX SNAP is designed to facilitate bulk trading of securities on a lit market and to minimize speed and information advantages enjoyed by only a few market participants.


Kirnberger temperament

Kirnberger temperament is an irregular temperament developed in the second half of the 18th century by Johann Kirnberger. Kirnberger was a student of Johann Sebastian Bach, held great admiration for his teacher and was one of his principal proponents.
The first Kirnberger temperament, "Kirnberger I", had similarities to Pythagorean temperament, which stressed the importance of perfect fifths all throughout the circle of fifths. A complete circle of perfect fifths is not possible, because when the circle comes to an end at the tone it began, it will have overshot its original pitch. Thus, if one tunes C-G, G-D, D-A, A-E, E-B, B-F, F-C, C-G (A), A-E, E-B, B-F, F-C... the new "C" will not be the same frequency as the first. The two "C"s will have a discrepancy of about 23 cents (a comma), which would be unacceptable. This difference between the initial "c" and final "c" that is derived from performing a series of perfect tunings is generally referred to as the "Pythagorean comma". In Kirnberger I, the D-A fifth is reduced by a syntonic comma, making the major thirds F-A, C-E, G-B, and D-F pure, though the fifth based on D is a ratio of 40/27 instead of 3/2. Many tuning systems have been developed to "spread around" that comma, that is, to divide that anomalous musical space among the other intervals of the scale.
Practical Temperaments: Kirnberger II.
Kirnberger's first method of compensating for and closing the circle of fifths was to split the "wolf" interval, known to those who have used meantone temperaments, in half between two different fifths. That is, to compensate for the one extra comma, he removed half a comma from two of the formerly perfect fifths in order to complete the circle. In so doing, he allowed the remaining fifths to stay pure. At the time, however, pure thirds were more valued than pure fifths (meantone temperament had eight pure thirds and sacrificed four entire chords to achieve this end.) So, Kirnberger allowed for three pure thirds, the rest being slightly wide and the worst being three Pythagorean thirds (22 cents wider than pure) on the opposite end of the circle from the pure thirds. To put it graphically:
 C-----G-----D------A-----E-----B-----F#-----C#-----Ab(G#)-----Eb-----Bb-----F-----C
 p p -1/2 -1/2 p p p p p p p p
 |__________pure 3rd______|
 |__________pure 3rd______|
 |_______pure 3rd________|
 |__________Pythag. 3rd_________|
 |_________Pythag. 3rd___________|
 |________Pythag. 3rd___________|
The above table represents Kirnberger II temperament. The first row under the intervals shows
either a "p" for pure, or "-1/2" for those intervals narrowed to close the circle of fifths (D-A), (A-E). Below these are shown the pure 3rds (between C-E, G-B, D-F), and Pythagorean (very wide) 3rds (between B-D, F-A(B), D-F.)
Temperament, however, is a give-and-take situation: none is a perfect solution. It must also be remembered that temperament applies only to instruments with fixed pitch: any keyboard instrument, lutes, viols, and so forth. Wind musicians, singers and string players all have a certain degree of flexibility concerning the exact pitch and intonation of what they play and may therefore be free of such restrictive systems. When the two classes of players come together, it is important when evaluating a temperament to consider the tendencies of the instruments vs. those of the temperament. Kirnberger II would only have been applicable to keyboard instruments such as the harpsichord and organ. The advantages of this system are its three pure major thirds and its ten pure fifths; the disadvantages are, of course, the two narrow "half-wolf" fifths and the three Pythagorean, super-wide thirds. The chords are not unusable but certainly must not be used frequently or in close succession within the course of a piece.
Kirnberger III.
After some disappointment with his sour, narrow fifths, Kirnberger experimented further and developed another possibility, later named the Kirnberger III.
This temperament splits the Syntonic comma between four fifths instead of two. 1/4-comma tempered fifths are used extensively in meantone and are much easier to tune and to listen to. This also eliminates two of the three pure thirds found in Kirnberger II. Therefore, only one third remains pure (between C and E), and there are fewer Pythagorean thirds. A greater middle ground is thus reached in this improvement, and each key is closer to being equal to the next. The drawback is an aesthetic one: fewer chords have pure thirds and fifths. But every temperament system has a give-and-take compromise; each has to find a way of dealing with the comma.


2893 Peiroos

2893 Peiroos is a large Jupiter trojan from the Trojan camp, approximately in diameter. It was discovered on 30 August 1975, by astronomers of the Felix Aguilar Observatory at the Leoncito Astronomical Complex in Argentina. The D-type asteroid has a rotation period of 8.96 hours and belongs to the 40 largest Jupiter trojans. It was named after Peiroos (Peirous) from Greek mythology.
Orbit and classification.
"Peiroos" is a dark Jovian asteroid orbiting in the trailing Trojan camp at Jupiter's Lagrangian point, 60° behind its orbit in a 1:1 resonance "(see Trojans in astronomy)". It is a non-family asteroid in the Jovian background population. It orbits the Sun at a distance of 4.8–5.5 AU once every 11 years and 8 months (4,269 days; semi-major axis of 5.15 AU). Its orbit has an eccentricity of 0.08 and an inclination of 15° with respect to the ecliptic.
The body's observation arc begins with its first observation as "" at Heidelberg Observatory in January 1933, more than 42 years prior to its official discovery observation at Leoncito.
Physical characteristics.
In the Tholen classification, "Peiroos" has been characterized as a dark D-type asteroid.
Rotation period.
In October 1989, a rotational lightcurve of "Peiroos" was obtained from photometric observations by German and Italian astronomers. Lightcurve analysis gave a well-defined rotation period of 8.96 hours with a brightness variation of 0.30 magnitude (). Between 2015 and 2017, photometric observations by Robert Stephens and collaborators at the Center for Solar System Studies in Landers, California, gave two concurring periods of 8.951 and 8.99 hours, both with an amplitude of 0.31 magnitude ().
Diameter and albedo.
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, "Peiroos" measures between 86.76 and 87.46 kilometers in diameter and its surface has an albedo between 0.0469 and 0.048.
The "Collaborative Asteroid Lightcurve Link" derives an albedo of 0.0588 and a diameter of 87.67 kilometers based on an absolute magnitude of 8.98.
Naming.
This minor planet was named after Peiroos (Peirous), Thracian war leader from the city of Aenus and an ally of King Priam who fought courageously to defend Troy against the Greek during the Trojan War. The official naming citation was published by the Minor Planet Center on 25 September 1988 ().


Fan chart (time series)

In time series analysis, a fan chart is a chart that joins a simple line chart for observed past data, by showing ranges for possible values of future data together with a line showing a central estimate or most likely value for the future outcomes. As predictions become increasingly uncertain the further into the future one goes, these forecast ranges spread out, creating distinctive wedge or "fan" shapes, hence the term. Alternative forms of the chart can also include uncertainty for past data, such as preliminary data that is subject to revision.
The term "fan chart" was coined by the Bank of England, which has been using these charts and this term since 1997 in its "Inflation Report" to describe its best prevision of future inflation to the general public. Fan charts have been used extensively in finance and monetary policy, for instance to represent forecasts of inflation.
Implementation.
Predicted future values can be diagrammed in various ways; most simply, by a single predicted value, and an upper and lower range around that (three lines total), or by various future intervals, depicted by varying degrees of shading (darkest near the center of the range, fainter near the ends of the range).
There are several ways to represent the forecast density depending on the shape of the forecasting distribution.
In the Bank of England's implementation it is assumed that the forecast distribution is a two piece normal or split normal density. This density results from joining the two-halves of corresponding normal densities with the same mode but different variances. As a result, the split normal density is non-symmetric and uni-modal. In this case, inflation forecast fan charts are usually accompanied with the balance of risks, the probability that the future inflation falls below its modal forecast. In this way, central banks that employ inflation targeting report to the general public not only the more likely forecasts of the inflation rate "but also its balance of risks"!
The split normal density is completely characterized by three parameters, the mode, variance and skewness. Therefore, the fan chart ranges depend on these parameters only. and
In a central bank that employs inflation targeting, the three moments of the inflation forecast distribution are determined as follows:


5234 Sechenov


Instructions per second

Instructions per second (IPS) is a measure of a computer's processor speed. For complex instruction set computers (CISCs), different instructions take different amounts of time, so the value measured depends on the instruction mix; even for comparing processors in the same family the IPS measurement can be problematic. Many reported IPS values have represented "peak" execution rates on artificial instruction sequences with few branches and no cache contention, whereas realistic workloads typically lead to significantly lower IPS values. Memory hierarchy also greatly affects processor performance, an issue barely considered in IPS calculations. Because of these problems, synthetic benchmarks such as Dhrystone are now generally used to estimate computer performance in commonly used applications, and raw IPS has fallen into disuse.
The term is commonly used in association with a metric prefix (k, M, G, T, P, or E) to form kilo instructions per second (kIPS), million instructions per second (MIPS), and billion instructions per second (GIPS) and so on. Formerly TIPS was used occasionally for "thousand ips".
Computing.
IPS can be calculated using this equation:
However, the instructions/cycle measurement depends on the instruction sequence, the data and external factors.
Thousand instructions per second (TIPS/kIPS).
Before standard benchmarks were available, average speed rating of computers was based on calculations for a mix of instructions with the results given in kilo Instructions Per Second (kIPS). The most famous was the Gibson Mix, produced by Jack Clark Gibson of IBM for scientific applications in 1959.
Other ratings, such as the ADP mix which does not include floating point operations, were produced for commercial applications. The thousand instructions per second (kIPS) unit is rarely used today, as most current microprocessors can execute at least a million instructions per second.
The Gibson Mix.
Gibson divided computer instructions into 12 classes, based on the IBM 704 architecture, adding a 13th class to account for indexing time. Weights were primarily based on analysis of seven scientific programs run on the 704, with a small contribution from some IBM 650 programs. The overall score was then the weighted sum of the average execution speed for instructions in each class.
Millions of instructions per second (MIPS).
The speed of a given CPU depends on many factors, such as the type of instructions being executed, the execution order and the presence of branch instructions (problematic in CPU pipelines). CPU instruction rates are different from clock frequencies, usually reported in Hz, as each instruction may require several clock cycles to complete or the processor may be capable of executing multiple independent instructions simultaneously. MIPS can be useful when comparing performance between processors made with similar architecture (e.g. Microchip branded microcontrollers), but they are difficult to compare between differing CPU architectures. This led to the term "Meaningless Indices of Performance" being popular amongst technical people by the mid-1980s.
For this reason, MIPS has become not a measure of instruction execution speed, but task performance speed compared to a reference. In the late 1970s, minicomputer performance was compared using "VAX MIPS", where computers were measured on a task and their performance rated against the VAX 11/780 that was marketed as a "1 MIPS" machine. (The measure was also known as the "VAX Unit of Performance" or VUP.) This was chosen because the 11/780 was roughly equivalent in performance to an IBM System/370 model 158–3, which was commonly accepted in the computing industry as running at 1 MIPS.
Many minicomputer performance claims were based on the Fortran version of the Whetstone benchmark, giving Millions of Whetstone Instructions Per Second (MWIPS). The VAX 11/780 with FPA (1977) runs at 1.02 MWIPS.
Effective MIPS speeds are highly dependent on the programming language used. The Whetstone Report has a table showing MWIPS speeds of PCs via early interpreters and compilers up to modern languages. The first PC compiler was for BASIC (1982) when a 4.8 MHz 8088/87 CPU obtained 0.01 MWIPS. Results on a 2.4 GHz Intel Core 2 Duo (1 CPU 2007) vary from 9.7 MWIPS using BASIC Interpreter, 59 MWIPS via BASIC Compiler, 347 MWIPS using 1987 Fortran, 1,534 MWIPS through HTML/Java to 2,403 MWIPS using a modern C/C++ compiler.
For the most early 8-bit and 16-bit microprocessors, performance was measured in thousand instructions per second (1000 kIPS = 1 MIPS).
"zMIPS" refers to the MIPS measure used internally by IBM to rate its mainframe servers (zSeries, IBM System z9, and IBM System z10).
"Weighted million operations per second (WMOPS)" is a similar measurement, used for audio codecs.


Spectral line

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules. These "fingerprints" can be compared to the previously collected "fingerprints" of atoms and molecules, and are thus used to identify the atomic and molecular components of stars and planets, which would otherwise be impossible.
Types of line spectra.
Spectral lines are the result of interaction between a quantum system (usually atoms, but sometimes molecules or atomic nuclei) and a single photon. When a photon has about the right amount of energy (which is connected to its frequency) to allow a change in the energy state of the system (in the case of an atom this is usually an electron changing orbitals), the photon is absorbed. Then it will be spontaneously re-emitted, either in the same frequency as the original or in a cascade, where the sum of the energies of the photons emitted will be equal to the energy of the one absorbed (assuming the system returns to its original state).
A spectral line may be observed either as an emission line or an absorption line. Which type of line is observed depends on the type of material and its temperature relative to another emission source. An absorption line is produced when photons from a hot, broad spectrum source pass through a cold material. The intensity of light, over a narrow frequency range, is reduced due to absorption by the material and re-emission in random directions. By contrast, a bright emission line is produced when photons from a hot material are detected in the presence of a broad spectrum from a cold source. The intensity of light, over a narrow frequency range, is increased due to emission by the material.
Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium capable of letting light pass through it. Several elements were discovered by spectroscopic means, including helium, thallium, and caesium. Spectral lines also depend on the physical conditions of the gas, so they are widely used to determine the chemical composition of stars and other celestial bodies that cannot be analyzed by other means, as well as their physical conditions.
Mechanisms other than atom-photon interaction can produce spectral lines. Depending on the exact physical interaction (with molecules, single particles, etc.), the frequency of the involved photons will vary widely, and lines can be observed across the electromagnetic spectrum, from radio waves to gamma rays.
Nomenclature.
Strong spectral lines in the visible part of the spectrum often have a unique Fraunhofer line designation, such as K for a line at 393.366 nm emerging from singly-ionized Ca+, though some of the Fraunhofer "lines" are blends of multiple lines from several different species. In other cases the lines are designated according to the level of ionization by adding a Roman numeral to the designation of the chemical element, so that Ca+ also has the designation Ca II or CaII. Neutral atoms are denoted with the Roman numeral I, singly ionized atoms with II, and so on, so that, for example, FeIX (IX, Roman nine) represents eight times ionized iron.
More detailed designations usually include the line wavelength and may include a multiplet number (for atomic lines) or band designation (for molecular lines). Many spectral lines of atomic hydrogen also have designations within their respective series, such as the Lyman series or Balmer series. Originally all spectral lines were classified into series: the "Principle series", "Sharp series", and "Diffuse series". These series exist across atoms of all elements, and the patterns for all atoms are well-predicted by the Rydberg-Ritz formula. For this reason, the NIST spectral line database contains a column for Ritz calculated lines. These series were later associated with suborbitals.
Line broadening and shift.
There are a number of effects which control spectral line shape. A spectral line extends over a range of frequencies, not a single frequency (i.e., it has a nonzero linewidth). In addition, its center may be shifted from its nominal central wavelength. There are several reasons for this broadening and shift. These reasons may be divided into two general categories – broadening due to local conditions and broadening due to extended conditions. Broadening due to local conditions is due to effects which hold in a small region around the emitting element, usually small enough to assure local thermodynamic equilibrium. Broadening due to extended conditions may result from changes to the spectral distribution of the radiation as it traverses its path to the observer. It also may result from the combining of radiation from a number of regions which are far from each other.
Broadening due to local effects.
Natural broadening.
The lifetime of excited states results in natural broadening, also known as lifetime broadening. The uncertainty principle relates the lifetime of an excited state (due to spontaneous radiative decay or the Auger process) with the uncertainty of its energy. A short lifetime will have a large energy uncertainty and a broad emission. This broadening effect results in an unshifted Lorentzian profile. The natural broadening can be experimentally altered only to the extent that decay rates can be artificially suppressed or enhanced.
Thermal Doppler broadening.
The atoms in a gas which are emitting radiation will have a distribution of velocities. Each photon emitted will be "red"- or "blue"-shifted by the Doppler effect depending on the velocity of the atom relative to the observer. The higher the temperature of the gas, the wider the distribution of velocities in the gas. Since the spectral line is a combination of all of the emitted radiation, the higher the temperature of the gas, the broader the spectral line emitted from that gas. This broadening effect is described by a Gaussian profile and there is no associated shift.
Pressure broadening.
The presence of nearby particles will affect the radiation emitted by an individual particle. There are two limiting cases by which this occurs:
Pressure broadening may also be classified by the nature of the perturbing force as follows:
Inhomogeneous broadening.
"Inhomogeneous broadening" is a general term for broadening because some emitting particles are in a different local environment from others, and therefore emit at a different frequency. This term is used especially for solids, where surfaces, grain boundaries, and stoichiometry variations can create a variety of local environments for a given atom to occupy. In liquids, the effects of inhomogeneous broadening is sometimes reduced by a process called "motional narrowing".
Broadening due to non-local effects.
Certain types of broadening are the result of conditions over a large region of space rather than simply upon conditions that are local to the emitting particle.
Opacity broadening.
Electromagnetic radiation emitted at a particular point in space can be reabsorbed as it travels through space. This absorption depends on wavelength. The line is broadened because the photons at the line center have a greater reabsorption probability than the photons at the line wings. Indeed, the reabsorption near the line center may be so great as to cause a self reversal in which the intensity at the center of the line is less than in the wings. This process is also sometimes called self-absorption.
Macroscopic Doppler broadening.
Radiation emitted by a moving source is subject to Doppler shift due to a finite line-of-sight velocity projection. If different parts of the emitting body have different velocities (along the line of sight), the resulting line will be broadened, with the line width proportional to the width of the velocity distribution. For example, radiation emitted from a distant rotating body, such as a star, will be broadened due to the line-of-sight variations in velocity on opposite sides of the star. The greater the rate of rotation, the broader the line. Another example is an imploding plasma shell in a Z-pinch.
Radiative broadening.
Radiative broadening of the spectral absorption profile occurs because the on-resonance absorption in the center of the profile is saturated at much lower intensities than the off-resonant wings. Therefore, as intensity rises, absorption in the wings rises faster than absorption in the center, leading to a broadening of the profile. Radiative broadening occurs even at very low light intensities.
Combined effects.
Each of these mechanisms can act in isolation or in combination with others. Assuming each effect is independent, the observed line profile is a convolution of the line profiles of each mechanism. For example, a combination of the thermal Doppler broadening and the impact pressure broadening yields a Voigt profile.
However, the different line broadening mechanisms are not always independent. For example, the collisional effects and the motional Doppler shifts can act in a coherent manner, resulting under some conditions even in a collisional "narrowing", known as the Dicke effect.
Spectral lines of chemical elements.
Visible light.
For each element, the following table shows the spectral lines which appear in the visible spectrum at about 400-700 nm.
Other wavelengths.
Without qualification, "spectral lines" generally implies that one is talking about lines with wavelengths which fall into the range of the visible spectrum. However, there are also many spectral lines which show up at wavelengths outside this range. At the much shorter wavelengths of x-rays, these are known as characteristic X-rays. Other frequencies have atomic spectral lines as well, such as the Lyman series, which falls in the ultraviolet range.


Trauma symptom inventory

The Trauma Symptom Inventory (TSI) is a Psychological evaluation/assessment instrument that taps symptoms of Posttraumatic stress disorder and other posttraumatic emotional problems. It was originally published in 1995 by its developer, John Briere. It is one of the most widely used measures of posttraumatic symptomatology.
The TSI is relatively unique in comparison to other measures of posttraumatic symptomatology, in that it is a multi-scale instrument, including 10 scales of various forms of clinical psychopathology related to psychological trauma. Also unique, it has three validity scales in order to assess the trauma victim's test-taking attitude, such as overreporting, underreporting and inconsistency. The TSI was not developed to detect the Malingering of posttraumatic stress disorder although clinicians have used it to do so. Research shows that the TSI serves as a general validity screen but should be used cautiously in detecting malingered PTSD.
Original psychometric data on the TSI demonstrated statistically adequate internal consistency (alphas ranging from .84 to .87). Validity with a civilian trauma-exposed sample has been demonstrated, with substantial relationships found between the TSI's clinical scale scores and other established measures of PTSD. Further corroboration of the TSI's psychometric properties, with trauma-exposed military veterans, was recently documented.
In 2011 a second edition of the TSI was published (TSI-2), Initial research demonstrated improved ability to detect simulated PTSD. Research in Sweden found the TSI-2 to be statistically sound and a good broad-spectrum assessment instrument.


Shure SM57

The Shure SM57 is a low-impedance cardioid dynamic microphone made by Shure Incorporated and commonly used in live sound reinforcement and studio recording. It is one of the best-selling microphones in the world. It is used extensively in amplified music and has been used for speeches by every U.S. president since its introduction in 1965. In 2004, honoring its four decades of "solid, dependable performance", it was inducted into the first-ever TEC Awards TECnology Hall of Fame.
Background.
The origin of SM57 may be traced to 1937, when Shure engineer Benjamin Bauer developed the first single-element directional microphone, the Unidyne, which had a cardioid pickup pattern. In 1959, another Shure engineer, Ernie Seeler, advanced the art of microphone design significantly with the Unidyne III. Seeler torture-tested the Unidyne III during three years of research and development and thereby, produced the SM series of rugged and reliable Shure microphone capsules. The "SM" stands for Studio Microphone; Seeler was an aficionado of classical music and expected the SM57 to be used for orchestras. Because he "despised" rock music, the TEC Foundation said that it was ironic that the microphone has become "a mainstay of rock music."
Characteristics.
The SM57 uses the same capsule as the popular SM58. Like the SM58, the SM57 is fitted with an XLR connector and features a balanced output, which helps to minimize electrical hum and noise pickup. According to Shure, the frequency response extends from 40 Hertz (Hz) to 15 kHz. The SM57 is manufactured in the United States, Mexico, and China.
The Shure A2WS is an accessory windscreen for the SM57 that attenuates wind noise and plosives ("pop" sounds), and protects the microphone capsule.
Use.
The SM57 is a popular choice of musicians due to its sturdy construction and ability to work well with instruments that produce high sound pressure levels, such as percussion instruments and electric guitars. The School of Audio Engineering (SAE) recommends the SM57 (along with other makes and models) for four roles in a drum kit: kick drum, snare drum, rack toms, and floor tom. The cardioid pickup pattern of the microphone reduces the pickup of unwanted background sound and the generation of acoustic feedback. SM57s have also been a staple when reinforcing the sound from guitar amplifiers.
In a more unconventional fashion, the SM57 has been favoured by some as a vocal mic, both live and in the studio. Notable singers known to have recorded vocals with an SM57 include Anthony Kiedis, Brandon Flowers, Madonna, David Bowie, John Lennon, Jack White, Bjork, Peter Gabriel, Paul Rodgers, Tom Waits, Wayne Coyne, Tom Petty Alice Cooper, Erykah Badu, Caleb Followill and Raphael Saadiq. An early model of the mic, the Unidyne 545 was used on "Pet Sounds" for Brian Wilson's vocal tracks.
Every U.S. president since Lyndon B. Johnson has delivered speeches through an SM57. It became the lectern microphone of the White House Communications Agency in 1965, the year of its introduction, and remains so.
Due to its popularity, the SM57 has been counterfeited frequently by manufacturers in China and Thailand. Shure Distribution UK reports that the SM57, SM58, Beta 57A, and Beta 58A are their microphones that are most commonly counterfeited. In 2006, Shure mounted a campaign against the trading of counterfeit microphones.


2098 Zyskin

2098 Zyskin, provisional designation , is a vestoid asteroid from the inner regions of the asteroid belt, approximately 10 kilometers in diameter. It was discovered by Russian–Ukrainian astronomer Lyudmila Zhuravleva at the Crimean Astrophysical Observatory in Nauchnyj on 18 August 1972. The asteroid was named for surgeon Lev Zyskin (1930–1994).
Orbit and classification.
"Zyskin" is a member of the Vesta family. Asteroids with these spectral and orbital characteristics are thought to have all originated from the "Rheasilvia crater", a large impact crater on the south-polar surface of 4 Vesta, which is the main-belt's second-most-massive asteroid after 1 Ceres. It orbits the Sun in the inner main-belt at a distance of 2.1–2.7 AU once every 3 years and 9 months (1,378 days). Its orbit has an eccentricity of 0.13 and an inclination of 6° with respect to the ecliptic.
First identified as at Johannesburg Observatory, the body's first used observation was taken at Goethe Link Observatory in 1957, when it was identified as , extending the asteroid's observation arc by 15 years prior to its official discovery observation.
Physical characteristics.
In October 2010, a rotational lightcurve of "Zyskin" was obtained from photometric observations made at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 3.920 hours with a brightness variation of 0.08 magnitude ().
Diameter and albedo.
According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, "Zyskin" measures between 10.44 and 12.8 kilometers in diameter, and its surface has an albedo between 0.10 and 0.18. The "Collaborative Asteroid Lightcurve Link" assumes a standard albedo for S-type asteroids of 0.20 and calculates a diameter of 8.9 kilometers with an absolute magnitude of 12.61.
Naming.
This minor planet was named in honor of Lev Yur'evich Zyskin, professor at the Crimean Medical Institute, who was head of its Pulmonary Surgery Center. Lyudmila Zhuravleva also discovered 1858 Lobachevsk on the same day she discovered "2098 Zyskin". She is a prolific astronomer with more than 200 minor planets discovered between 1972 and 1992 and (still) ranks in 61st position on the Minor Planet Center's discoverer-list as of 2015. The official naming citation was published by the Minor Planet Center on 1 April 1980 ().


Amulet Records

Amulet Records is a record label based in New Jersey specialising in percussion, avant-garde, and experimental music. The label was established by the percussionist composer and visual artist Billy Martin in 1997, inspired by a percussion session with the Lounge Lizards drummers Grant Calvin Weston and Billy Martin who released their first duet record "Percussion Duets" in 1997.
Celebrating its tenth anniversary, the catalogue has grown to titles ranging from percussion repertoire produced by Martin; the "Mozown series", dedicated to preserving vintage Bob Moses recordings; hip-hop and remix projects; a "Sound Healing" series and other visionary music and art.


SPECvirt

SPECvirt_sc2010 is a computer benchmark that evaluates the performance of a server computer for virtualization. It is available from the Standard Performance Evaluation Corporation (SPEC). It was introduced in July, 2010.
The SPECvirt_sc2010 benchmark measures the maximum number of workloads that a platform can simultaneously run while maintaining specific quality of service metrics. Each workload, called a tile, consists of a specific set of virtual machines.
In addition to generating results that show performance, the benchmark can also be used to generate performance per watt results.
The SPECvirt_sc2010 was not supported by SPEC from February 26, 2014 and its successor is SPECvirt_sc2013.


Diploma Entrance Test Odisha

Diploma Entrance Test, Odisha is a complete state government controlled centralised entrance examination for getting admission to many government & private diploma engineering schools or polytechnics in Odisha. Students can get admission to Diploma Engineering, Diploma Non-Engineering like Hotel Management, Hospitality management & Film Making studies etc. after 10th, ITI & +2 Science.
Examination Procedure.
Candidates can appear in this examination after 10th, ITI or after +2 science. There is two types of admission done in this process. First one is freshers for getting admission to first semester or first year & another one is lateral entry, that is after ITI or +2 Science getting admission to second year or third semester. For freshers students the test is based on general Science & Mathematics, but for lateral students the test prospective is harder than the freshers students. Also the lateral students have only 20% over the whole seats and no reservation quota is available for them.


9 Metis

Metis (minor planet designation: 9 Metis) is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a percent of the total mass of the asteroid belt.
Metis passed within 0.034AU, or , of Vesta on 19 August 2004.
Discovery and naming.
Metis was discovered by Andrew Graham on 25 April 1848, at Markree Observatory in Ireland; it was his only asteroid discovery. It also has been the only asteroid to have been discovered as a result of observations from Ireland until 7 October 2008, when, 160 years later, Dave McDonald from observatory J65 discovered (281507) 2008 TM9. Its name comes from the mythological Metis, a Titaness and Oceanid, daughter of Tethys and Oceanus. The name "Thetis" was also considered and rejected (it would later devolve to 17 Thetis).
Characteristics.
Metis' direction of rotation is unknown at present, due to ambiguous data. Lightcurve analysis indicates that the Metidian pole points towards either ecliptic coordinates (β, λ) = (23°, 181°) or (9°, 359°) with a 10° uncertainty. The equivalent equatorial coordinates are (α, δ) = (12.7 h, 21°) or (23.7 h, 8°). This gives an axial tilt of 72° or 76°, respectively.
Hubble Space Telescope images and lightcurve analyses are in agreement that Metis has an irregular elongated shape with one pointed and one broad end. Radar observations suggest the presence of a significant flat area, in agreement with the shape model from lightcurves.
The Metidian surface composition has been estimated as 30–40% metal-bearing olivine and 60–70% Ni-Fe metal.
Light curve data on Metis led to an assumption that it could have a satellite. However, subsequent observations failed to confirm this. Later searches with the Hubble Space Telescope in 1993 found no satellites.
Family relationships.
Metis was once considered to be a member of an asteroid family known as the Metis family, but more recent searches for prominent families did not recognize any such group, nor is a clump evident in the vicinity of Metis by visual inspection of proper orbital element diagrams.
However, a spectroscopic analysis found strong spectral similarities between Metis and 113 Amalthea, and it is suggested that these asteroids may be remnants of a very old (at least ~1 Ga) dynamical family whose smaller members have been pulverised by collisions or perturbed away from the vicinity. The putative parent body is estimated to have been 300 to 600 km in diameter (Vesta-sized) and differentiated. Metis would be the relatively intact core remnant (though smaller than 16 Psyche), and Amalthea a fragment of the mantle, with 90% of the original body unaccounted for. Coincidentally, both Metis and Amalthea have namesakes among Jupiter's inner moons.
Occultations.
In 1984 an occultation of a star produced seven chords that Kristensen used to derive an ellipsoidal profile of 210×170 km. On 6 August 1989, Metis occulted a magnitude 8.7 star producing five chords suggesting a diameter of 173.5 km. Observations of an occultation on 11 February 2006, produced only two chords indicating a minimum diameter 156 km. All three of these occultations fit the ellipsoid 222×182×130 km suggested by Baer.
On 7 March 2014, Metis occulted the star HIP 78193 (magnitude 7.9) over parts of Europe and the Middle East.


Graph literacy

Graph literacy is the ability to understand information that presented graphically, which are including general knowledge about how to extract information and make inferences from different graphical formats. Although related, graph literacy is distinct from other forms of literacy (e.g., general health literacy or numeracy) in the sense that it relates more specifically to one's ability to obtain meaning from information presented graphically. It can include the storage of mental representations in long-term memory, knowledge about the properties of different types of formats, and procedures to interpret them. However, similar to other types of literacy, higher graph literacy is associated with higher education levels and suggests that developing the skills required to interpret graphical information requires knowledge that is acquired through formal education and experience.
Graph literacy is very important in everyday life: graphs appear throughout the published media, in newspapers and magazines, on TV and on the internet, and are used to provide information for many important decisions including medical, nutritional, financial and political choices. Yet many people can have difficulty understanding even the simplest graphs. Up to one third of the general population lacks the skills needed to understand basic numerical formats (e.g., percentages or ratios) and basic graphic displays (such as bar or pie charts, line graphs, or icon arrays). While graphical displays can improve understanding and comprehension of quantitative information, such as the risks and benefits of medical treatments, they may not be helpful for everyone. Visual displays may be of greater help to people with low numeracy whereas numbers may be better for people who have poor graph literacy. Determining what type of information displays lead to better comprehension of information, and for whom, is an ongoing topic of research, particularly within the area of risk communication.
Graph comprehension.
Graphical displays can contain a vast amount of information such as information contained within the title, labels and axes, but also within features of the display (e.g., size, spacing, patterns in the data) that can vary in their complexity (e.g., multiple variables). Both perceptual and cognitive processes are required to interpret the information contained within a graphic display. Different processes are required to extract information depending on the task or goal, such as extracting a specific value or making inferences based on the data (e.g., predicting future trends).
Graph comprehension depends not only on people's knowledge, familiarity or experience with reading graphic displays but also on the way in which the graphic is designed. For example, some features of graphs make use of spatial-to-conceptual mappings that are grounded in our everyday experience, such as the tendency for higher bars to relate to greater or larger quantities. However, other aspects need to be learned, such as arbitrary graph conventions (e.g., axis labels and scales). Graph literacy can affect how people attend to and encode some of these features.
Graph literacy scale.
The Graph Literacy Scale consists of 13 items and measures three abilities related to graph comprehension (see ) (1) the ability to read the data, that is, to find specific information in the graph; (2) the ability to read between the data, that is, to find relationships in the data as shown on the graph; and (3) the ability to read beyond the data, or make inferences and predictions from the data. The scale was validated in a survey conducted on probabilistic national samples in Germany and the USA.
Previous measures of graph comprehension have tended to focus on the comprehension of specific features or types of graphs (e.g., line or bar graphs), incorporate relatively complex items, or have been developed in the context of examining the effects of teaching methods on the acquisition of graph skills (e.g.,). Some numeracy scales include a few items related to the comprehension of graphical information but these are limited in their ability to measure a range of graphs, features, or tasks.


BB Phoenicis

BB Phoenicis is a variable star in the constellation of Phoenix. It has an average visual apparent magnitude of 6.17, being visible to the naked eye with excellent viewing conditions. From parallax measurements by the Gaia spacecraft, it is located at a distance of from Earth. Its absolute magnitude is calculated at 0.6.
BB Phoenicis is a Delta Scuti variable, and shows stellar pulsations that cause brightness variations with an amplitude of 0.04 magnitudes. Its variability was discovered by accident in 1981, when the star was used as a comparison star for the eclipsing binary AG Phoenicis. Photometric and spectroscopic data have allowed the detection of at least 13 modes of radial and non-radial pulsations, the strongest one having a period of 0.174 days and an amplitude of 11.1 milli-magnitudes. Observations in different epochs show evidence that the pulsations modes vary in amplitude, which is common among Delta Scuti variables. Pulsation models indicate that the stellar rotation axis is inclined by 50–70° in relation to the line of sight.
This star is classified as an F-type giant with a spectral type of F0/2III. It appears to be expanding after depleting all the nuclear hydrogen and leaving the main sequence. BB Phoenicis has an estimated mass of 2.25 times the solar mass and a radius of 4.7 times the solar radius. It is radiating 55 times the Sun's luminosity from its photosphere at an effective temperature of 7,200 K.


Portrait of Lotte

Portrait of Lotte is a time-lapse viral video involving a girl growing from a newborn in 1999 into a teenager. It was first posted by filmmaker Frans Hofmeester from Utrecht, Netherlands on 17 April 2012.
It has reached widespread and the video was used on a Sprint commercial.
Vince.
After 12 years of recording Lotte, Hoffmeester started recording videos of his son, Vince.
He described Lotte's video as being more "sweet" and Vince's as more "playful".
Background.
Hoffmeester recorded 15 second videos every week of his daughter, Lotte, from a newborn to a teenager and compiled them together to make a time-lapse video. He calls it "the ultimate coming of age time-lapse". He has done several videos of her being recorded to different ages, such as 12, 14, 16, 18 and 20 years old.
Hofmeester explains, "She was changing at such a rapid pace, that I felt the need to document the way she looked, to keep my memories intact".
Commenting on the occasions he found it difficult to get the footage required, he said, "Sometimes they did not feel like it. Then I said, 'Just one minute. Tell me about your ball game, did you win?' That way I stalled them so I could complete the shot".


List of longest bridges

This is a list of the world's longest bridges that are more than in length sorted by their full length above land and water. The main span is the longest span without any ground support
" Note: There is no standard way to measure the total length of a bridge. Some bridges are measured from the beginning of the entrance ramp to the end of the exit ramp. Some are measured from shoreline to shoreline. Yet others use the length of the total construction involved in building the bridge. Since there is no standard, no ranking of a bridge should be assumed because of its position in the list. Additionally, numbers are merely estimates and measures in U.S. customary units (feet) may be imprecise due to conversion rounding."


Table of the Elements

Table of the Elements is an American record label. It concentrates on re-released and specially recorded experimental music, including many avant-garde musicians of the 20th and 21st centuries, such as John Cale, Tony Conrad and La Monte Young, as well as lesser-known artists such as Loren Mazzacane Connors, Derek Bailey, Rhys Chatham, Fushitsusha/Keiji Haino, and Mats Gustafsson.
The label numbers its releases to correspond to symbols from the periodic table in increasing order of atomic weight, rather than using the traditional numerical system. The label hosted multiple-day experimental music festivals. It also releases recordings under two other imprints, Radium and Xeric.


Metrication in Canada

Metrication in Canada began in 1970 and ceased in 1985. While Canada has converted to the metric system for many purposes, there is still significant use of non-metric units and standards in many sectors of the Canadian economy and everyday life today. This is mainly due to historical ties with the United Kingdom, the traditional use of the imperial system of measurement in Canada, proximity to the United States, and strong public opposition to metrication during the transition period.
Before conversion.
Until the 1970s, Canada traditionally used the imperial measurement system, labelled as "Canadian units of measurement" under Schedule II of the "Weights and Measures Act" (R.S., 1985, c. W-6). These units have the same names and the same values as United States customary units, with the exception of capacity measures such as the gallon. For example, before metrication in Canada, gasoline was sold by the (imperial) gallon (about 4.55 litres). In cross-border transactions with the United States it was often unclear whether values quoted in gallons were referring to United States gallons (3.79 litres) or imperial gallons.
Conversion process.
The Liberal federal government of Pierre Trudeau first began implementing metrication in Canada in 1970 with a government agency dedicated to implementing the project, the Metric Commission, being established in 1971. By the mid-1970s, metric product labelling was introduced. In 1972, the provinces agreed to make all road signs metric by 1977. During the Labour Day weekend in 1977, every speed limit sign in the country was changed from mph to km/h. From the same time every new car sold had to have a speedometer that showed speed in km/h and distance in km. The distances on road signs were changed to kilometres during the next few months. Gasoline pumps changed from imperial gallons to litres in 1979.
There was some resistance to metrication, especially as the sectors of the economy where the federal Weights and Measures Act required metric to be used grew in number. The metrication of gasoline and diesel fuel sales in 1979 prompted 37 Progressive Conservative Members of Parliament to open a "freedom to measure" gas station in Carleton Place, Ontario, selling gas in both imperial gallons and litres. The city of Peterborough, Ontario, was a noted hotbed of opposition to metrication, having been one of the government's three test centres for the metrication process. Bill Domm, a Member of Parliament representing the riding of Peterborough, was one of the country's most outspoken opponents of metrication. During this period, a few government employees lost their jobs for their opposition to metrication. Neil Fraser, an official with Revenue Canada who publicly opposed mandatory metric conversion, was dismissed for "conduct unacceptable for a public servant".
Changeover.
Since 1976, the law requires that all prepackaged food products must declare their mass or their volume in metric units, though Canadian imperial units are still legally permitted on packaging. Milk has been thoroughly metric since 1980. In April 1975, Fahrenheit temperatures were replaced by Celsius. In September 1975, rainfall was first measured in millimetres and snow in centimetres. Since April 1976, wind speed, visibility, and barometric pressure have been in metric units, with the pressure in kilopascals instead of the hectopascals (millibars) used in most of the rest of the world. In September 1977, every speed-limit sign in the country was changed from miles per hour to kilometres per hour.
Metrication stalled.
The election of the Progressive Conservative government of Brian Mulroney in 1984 resulted in the abolition of the Metric Commission on March 31, 1985. This ended the process of affirmative metrication in Canada, and some regulations requiring metric measurements either have been repealed or are no longer enforced.
Training on metric conversion was not universal. Poor metrication training was a contributing factor to Air Canada Flight 143, the so-called Gimli Glider, running out of fuel mid-flight on July 23, 1983.
Notwithstanding the end of officially sanctioned metrication in Canada, most laws, regulations, and official forms exclusively use metric measurements. However, imperial measures still have legal definitions in Canada and can be used alongside metric units. Net quantity declarations on prepackaged products sold to consumers may be stated in metric units.
Common usage today.
Daily usage.
Canadians typically discuss the weather in degrees Celsius, purchase gasoline in litres, observe speed limits set in kilometres per hour (km/h), and read road signs and maps displaying distances in kilometres. Cars have metric speedometers and odometers, although most speedometers include smaller figures in miles per hour (mph). Fuel efficiency for new vehicles is published by Natural Resources Canada in litres per 100 kilometres, ("not" kilometres per litre as a direct equivalent of "miles per gallon") and miles per (imperial) gallon. Window stickers in dealer showrooms often include "miles per gallon" conversions. The railways of Canada such as the Canadian National and Canadian Pacific as well as commuter rail services, continue to measure their trackage in miles and speed limits in miles per hour (although urban railways including subways and light rail have adopted kilometres and kilometres per hour). Canadian railcars show weight figures in both imperial and metric. Canadian railways also maintain exclusive use of imperial measurements to describe train length and height in feet and train masses in short tons.
Canadians typically use a mix of metric and imperial measurements in their daily lives. The use of the metric and imperial systems varies according to generations. Newborns are measured in metric at hospitals, but the birth weight and length is also announced to family and friends in imperial units. Although Canadian driver's licences give height in centimetres, many Canadians also use imperial units to indicate height and weight. Most kitchen appliances in Canada are labelled with both degrees Celsius and Fahrenheit, and metric cooking measures are widely available; but Fahrenheit is often used for cooking, as are imperial cooking measurements, due to the import of kitchen appliances and recipes from the United States. Canadians also occasionally use imperial temperatures outside of the kitchen, such as when measuring the water temperature in a pool. Stationery and photographic prints are also sold in sizes based on inches and the most popular paper sizes, letter and legal, are sized in imperial units, though many agendas and notebooks are sold in ISO 216 sizes. Canadian football games continue to be played on fields measured in yards (with a gridiron layout with a length of 100.6 metres, or 110 yards, from one goal line to the other); golfers also expect courses to be measured in yards.
Experience.
The use of metric or imperial measurements varies by age and region. Canadians who have received only metric instruction in school (from the early 1970s) are more familiar with metric measurements. Quebec has implemented metrication more fully. The use of imperial units is more common in rural areas than in the rest of the country, where opposition to metrication was strongest, rather than in urban areas.
Canadians are exposed to both metric and imperial units, and it is not unusual for there to be references to both metres and feet, square metres and acres, or grams and ounces in the same conversation.
Temperature.
Despite the exclusive use of degrees Celsius in weather reports, some Canadians still use Fahrenheit. Most outdoor thermometers display temperatures in both Fahrenheit and Celsius. Additionally, outdoor signs usually display Celsius with occasional references to Fahrenheit. Inside newer buildings, digital and analog thermostats display temperature settings in degrees Celsius or Fahrenheit. Environment Canada still offers an imperial unit option beside metric units.
Products and retail.
Many food and retail products are sold according to metric units, though this is not always the case. The price of a piece of meat, for example a steak, is typically advertised per pound, but the price printed on the package is per kilogram; the latter is calculated. The prices of fruits and vegetables are usually advertised in pounds, although the price per kilogram is also displayed, usually in smaller type. More expensive items such as deli, meats, and fish are often advertised per 100 grams. Many, but not all, products are sold in imperial sizes, but labelled in metric units. An example of this is butter, which is sold in a 454 gram package (and labelled as such), even though it represents one pound (and in many cases is also labelled with the imperial unit). This is known as "soft metric" (as opposed to a "hard metric" system, where packages and measures are generally sold in "round numbers"; in a hard metric system, butter might come in a 500 g package). Mandatory nutrition facts labelling (the Nutrition Facts Table) uses metric units for several basic nutrients, although serving sizes can be described in any form of unit (can, cup, quantity, etc.).
In restaurants, wine is usually served by the litre, or bottle, but a wine glass is measured in ounces. A 750-millilitre bottle of hard liquor is referred to as a "twenty-sixer" or "two-six", referring to its volume in imperial fluid ounces, rounded down from 26.4. Similarly, fast food restaurants (e.g. McDonald's "Quarter Pounder") often advertise measurements of food and drink in US customary units, but converted to metric units, because either the containers are made to US standards, or the franchise is US-based and uses a standard size for its products. Thus in Canada a 20 US fluid ounce bottled soft drink is labelled as 591 mL (or occasionally rounded up to 600 mL). Beer in bottles continues to be 12 imperial fluid ounces (labelled as 341 mL), but beer in cans is filled to 12 US fluid ounces (labelled as 355 mL). There is also a larger sized beer bottle which is labelled as containing . Some of these package sizes have been introduced since Canadian metrication began; for example, the traditional Canadian soft drink can was 10 imperial fluid ounces (284 mL), later marketed as 280 mL. Only in the early 1990s did the US-derived 355 mL size displace it. Display sizes for screens on television sets and computer monitors almost always have their diagonals measured in inches. Bicycle frames and car wheel diameters are also usually described in inches; tire inflation is in pounds per square inch (psi). Standard and special fasteners like alloys, nuts, bolts, washers, studs, tapping, self drilling screw and socket screware are often quoted in both imperial and metric; products range from diameter up to .
Commercial usage.
Supermarkets will often advertise foods such as meats and produce "per pound", and small businesses are exempt from having metric scales and legally sell by the pound. While most supermarket scales display both metric and imperial units, products advertised by the pound in a supermarket flyer are invariably sold to the customer (at the point of sale) based on a price "per 100 grams" or "per kilogram".
Construction materials, including construction lumber and drywall, continue to be sold in imperial measurements; retrofitting metric-sized (designed for 400 mm centres) wallboard on old spaced studs is difficult. In English-speaking Canada commercial and residential spaces are mostly (but not exclusively) constructed using imperial units and advertised accordingly, while in French-speaking Quebec commercial and residential spaces are constructed in metres and advertised using both metric and imperial units as equivalents. However, the zoning by-laws and building codes that govern construction are in metric, although most building codes will also contain imperial equivalents. In addition, rural areas in Western Canada (Canadian Prairies) were mapped and segmented using the Dominion Land Survey. This based most rural roads on a mile measurement which when viewed from the air has the appearance of a checkerboard or grid. Because of this historical reason, it is still common to refer to distance in miles. In contrast, in much of southern Ontario the basic survey grid was based on a mile-and-a-quarter (1.25 mi), which corresponds almost exactly to a 2 kilometre grid and which makes miles no more natural than kilometres. 1.25 mi is equal to 100 chains (or 10 furlongs) and it was that sized grid that was used in the original surveys and thus would have been more familiar.
Free trade with the United States has resulted in continued exposure to the US system. Since the United States is Canada's largest trading partner and vice versa, Canadian exporters and importers must be accustomed to dealing in US customary units as well as metric.
Agriculture.
Canada uses an Avery or imperial bushel (36.369 litres) when selling oats, wheat, and other grains. When dealing with the US oat markets though, special attention must be paid to the definition of bushel weight because US uses a Winchester bushel (35.239 litres). In livestock auction markets, cattle are sold in dollars per hundredweight (short), whereas hogs are sold in dollars per hundred kilograms.
Health care.
In the health care system, metric units are often given precedence, although actual metric units may still be different than the United States (for example, for measurements of blood cholesterol, the units are millimole per litre, whereas they are milligram per decilitre in the United States). Most physicians chart patient height and weight in imperial units, and while most growth charts display both systems of measurement, the majority of hospitals officially document such parameters in metric. Dieticians still use kilocalories, and doctors use millimetres of mercury. While these units are metric derivatives, they are not metric units.
Engineering.
Because most fasteners, machine parts, pumps, piping, and all building materials are sold in imperial or US customary units, many mechanical and civil engineers in Canada mainly use imperial units for these items. Overall building dimensions for new construction are usually in SI units. . Many chemical, nuclear and electrical engineers and engineering physicists employ metric units. Unlike in the United States, Canadian engineers are not always educated in both systems but those who are not become keenly aware of the differences between the imperial, metric and US customary systems once they enter the workforce.
Trades.
Trades associated with machine work, such as machinists, automotive, and heavy duty technicians, frequently use both metric and imperial. Machines made in Canada often incorporate parts from other countries and thus the finished product may have both metric and imperial parts. Farm and industrial equipment manufactured in Canada will most often use inch system fasteners and structural steel, but fluid capacities are always listed in metric.
Building trades such as plumbing and carpentry often use imperial units. Rough timber, drywall, plywood, fasteners, pipes, and tubing are all sold in imperial units. Nails in hardware stores are measured in inches but sold in metric weight packages.
Electricians in every country use metric units such as volts and amperes, but motors and engines in Canadan are still often quoted in horsepower. Electric car motors are rated in kilowatts. However, Canada uses, among other things, the US American wire gauge standard instead of the square millimetre (mm2) used in the IEC 60228 standard of the International Electrotechnical Commission. Conduit sizes are in inch diameters, although some manufacturers include the metric size printed on the conduits (for example, , , ).
Firearms.
Imperial units remain in common use in firearms and ammunition on the international market. Cartridges may have either commercial or military descriptions. In the former, the manufacturer will choose a name for proprietary reasons, perhaps to associate the name with a brand or designer, or otherwise distinguish it from comparable cartridges. Typical terms include bullet or bore diameter, cartridge length or capacity, a proper name or company. Designs are registered with Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) or Commission internationale permanente pour l'épreuve des armes à feu portatives (CIP) for standardization. Canadian industry follows both conventions, but there is little appetite in the Canadian firearms industry or hobby to pursue metrification simply for the sake of conformity when the trade is global.
Military designations use technical nomenclature to avoid confusion or misrouting of supplies. There are several examples of similar names and similar design dimensions. For example, the civilian cartridge .303 Savage was introduced by the Savage Arms Company in 1894, but is incompatible with the .303 British used throughout the Commonwealth. The .308 Winchester cartridge derived from the 7.62×51mm NATO cartridge in the 1950s, with slight variations in production but not in external dimensions. All four examples are common small arms cartridges in Canada.
Imperial measures are often encountered in the description of cartridges, even when the cartridge is of a relatively recent product introduction (e.g. .204 Ruger, .17 HMR, where the calibre is expressed in decimal fractions of an inch). Ammunition which is classified in metric already is still kept metric (e.g. 9 mm, 7.62 mm). In the manufacture of ammunition, bullet and powder weights are expressed in terms of grains for both metric and imperial cartridges. The popular .30-30 Winchester is a calibre bullet originally loaded with 30 grains of smokeless gunpowder.
Print.
Canada uses the inch-based paper standard e.g. the US Letter (8.5 inches × 11 inches), rather than the metric-based A4 paper size (210 mm × 297 mm) used throughout most of the world. The government, however, uses a combination of ISO paper sizes, and CAN 2-9.60M "Paper Sizes for Correspondence" specifies P1 through P6 paper sizes, which are the US paper sizes rounded to the nearest 5 mm.
Air transportation.
Luggage restrictions and limits at Canadian airports are in metric values with soft imperial conversion values. Runway lengths are given in feet and speed in knots as in the US. Like a number of metric countries altitude is given in feet.
Fuel is nowadays measured in metric units. The Gimli Glider incident in July 1983 is a famous case of a kilogram–pound mistake, in which the miscalculation of the amount of fuel in an Air Canada airplane with a malfunctioning fuel gauge caused the plane to run out of fuel mid-flight.
Education regarding the imperial system.
In 2005, the Ontario government announced changes to the secondary-school mathematics curriculum that would allow imperial units to be taught along with metric units. This marked a departure from previous governments' efforts to make sure that the curriculum used only the metric system. This was done in light of the refusal or reluctance of much of the private sector to metricate; thus students had been leaving school unprepared for the units used in the workplace. Many other provinces and territories also include the imperial system of measurements as part of their educational curriculum.