Malaysian University English Test

The Malaysian University English Test (commonly abbreviated as MUET) is a test of English language proficiency, largely used for university admissions in Malaysia. The test is set and run by the Malaysian Examinations Council. MUET is largely recognised in Malaysia and Singapore, with limited recognition in other countries worldwide.
MUET is a prerequisite for admissions into all public universities and colleges in Malaysia. Besides that, public servants also take MUET as an English qualification and for promotion opportunities.
From 2012 onwards, MUET is administered three times a year, in March, July and November. Besides that, an alternative test, MUET on Demand, is also held in nearly every month for candidates who are urgent to get the MUET results. On average, 85,000 candidates sit for the MUET each time.
From 2021, MUET has undergone a major change in format.
Components, Scoring and Grading.
There are four components in MUET:
Starting from MUET 2021, the maximum scores for each component are 90, makes an aggregated score of 360. The scores are graded in nine bands, including half bands, with Band 5+ being the highest while Band 1.0 the lowest.
Prior to MUET 2020, the maximum scores for each component is 45 for Listening and Speaking, 120 for Reading Comprehension and 90 for Writing, with an aggregated score of 300. The scores are then graded in six bands, with Band 6 being the highest while Band 1 the lowest.
Locations and test dates.
The MUET test centres are largely in public secondary schools that offer Form Six, matriculation colleges, certain universities, as well as certain private and semi-private colleges.
Listening, Reading and Writing components are usually tested on the same day, normally the second or the fourth Saturday of the month. The Speaking component is held on separate days, usually before the written tests.


Canadian Academic English Language Assessment

The Canadian Academic English Language, or CAEL (), Assessment is a standardized test designed to measure English language proficiency for admission to college and university, and for membership in professional associations. Test takers read articles, listen to a lecture, answer questions, and write a short essay, as they would be expected to do in a first-year university or college classroom.
The CAEL Assessment is accepted by over 150 academic institutions across Canada and the United States as well as to several international institutions. The test is also accepted at a number of professional organizations, including the Canadian Veterinary Association, the Royal Architectural Institute of Canada, and the Immigration Consultants of Canada Regulatory Council (ICCRC).
The CAEL Assessment is developed in Canada, by Canadians. It incorporates Canadian English and accents as used in Canadian academic contexts and post-secondary institutions. The CAEL Assessment is a fully integrated and topic-based performance test. Test takers use the information from the Reading and Listening components to write their essay.
In June 2015, Paragon Testing Enterprises, a Canadian English language testing company and a subsidiary of the University of British Columbia, acquired the CAEL Assessment from Carleton University.
History.
The CAEL Assessment was first developed by Carleton University in 1987. It was created out of a need to standardize the existing English language test given to students requiring a proficiency test as part of their admission to Carleton. However, in June 2015, Paragon Testing Enterprises, a subsidiary of The University of British Columbia (UBC), acquired the test.
Paragon currently administers three tests: the Canadian English Language Proficiency Index Program (CELPIP), the Canadian Academic English Language (CAEL) Assessment, and the Language Proficiency Index (LPI). The CELPIP Test is one of two tests designated by Immigration, Refugees and Citizenship Canada (IRCC) as proof of English language proficiency for permanent resident status in Canada and Canadian citizenship. With the acquisition of the CAEL Assessment, Paragon Testing Enterprises retired the CELPIP- Academic Test.
CAEL Test Format.
The language tasks and activities in the CAEL Assessment are systematically sampled from those that are commonly undertaken within the university academic community. The content for the tasks are drawn from introductory university courses at times when professors are introducing new topics to their students with the expectation that the students know little or nothing about the content.
Topics for the CAEL Assessment are drawn from introductory university courses such as arts, sociology, anthropology, business, engineering, sports, law, and medicine. Possible topics include criminal behaviour, global warming, urban development, cultural diversity, weather systems, team management, competition, and organizational behaviour.
The total allotted test time is approximately 145 minutes (2 hours and 25 minutes). Some test centres offer the CAEL Assessment over 2 days, with the Written Assessment and the OLT held on separate days.
The CAEL Assessment has two parts: Part 1, the Written Assessment and Part 2, the Oral Language Test (OLT).
Written Assessment.
Reading.
The time allotted for the Reading section is 55 minutes. Test takers are given two readings that are on the same topic as the Listening and Writing components.
The readings are taken from the following sources:
Reading tasks include:
Listening.
The time allotted for the Listening section is 20 minutes. Test takers listen to a pre-recorded lecture and answer relevant questions on the same topic as the Reading and Writing components.
Listening tasks include:
Writing.
The time allotted for the Writing section 45 minutes. Test takers will use the information from the Reading and Listening components to write a short essay. It is encouraged that test takers plan their essays prior to writing.
The essay topic asks the test taker to:
Oral Language Test (OLT).
The time allotted for the Oral Language Test (OLT) is 25 minutes. The OLT is carried out on a computer equipped with a headset and microphone, however test takers will not be required to use the computer mouse or keyboard. The OLT may be taken before or after the Written Assessment.
It consists of five tasks which sample typified and recurring speech acts within college and university settings:
Scoring.
CAEL Assessment Scores are reported for Listening, Reading, Writing, and Speaking test components. The scores range from band level 10 to band level 90.
CAEL Band Descriptors.
Each band score corresponds to a descriptive statement summarizing the level of English language proficiency of a test taker.
Results.
Results of tests taken at Canadian test centres are available within 10 to 15 business days after the scheduled test date. However, the results of tests taken at international test locations are available within 20 business days after the scheduled test date.
Test takers’ test scores can be sent to five institutions, which is included in the registration fee. Institution details are provided by the test takers when registering online, or up to 4 days before the chosen test date. The official score reports will only be mailed to academic and professional institutions.
Test Centre Locations and Test Dates.
Test takers can currently take the CAEL Assessment at test centres across Canada and China.
To see the full list of test centres and their corresponding test dates, please visit the CAEL website: https://www.cael.ca/
Institutions that Accept CAEL.
The CAEL Assessment is accepted by over 150 academic institutions across Canada and internationally as proof of English proficiency. A number of professional associations also recognize the CAEL Assessment as proof of English language proficiency required for membership.
Other English Language Proficiency Tests.
Many post-secondary institutions in Canada and the United States of America require proof of English language proficiency as one of their admission requirements. The most common English language proficiency tests other than the CAEL Assessment include: the International English Language Testing System (IELTS), Test of English as a Foreign Language (TOEFL), the Michigan English Language Assessment Battery (MELAB), Test of English for International Communication (TOEIC), the Pearson Test of English Academic (PTE Academic), and more.


Micropound

The micropound (abbreviation μlb) is a small unit of avoirdupois weight and mass in the US and imperial systems of measurement, equal to one-millionth () pound. It is equal to exactly kg or about 453.6μg.


OICETS

The Optical Inter-orbit Communications Engineering Test Satellite (OICETS), also called Kirari, was an experimental satellite launched by JAXA to demonstrate interorbital communication between satellites through optical (laser) means. OICETS was originally slated for a launch on the second J-I launcher. Due to problems with that launcher, the launch had to be put on hold. Using the H-IIA was out of question: it would have been overkill to use the H-IIA to send a satellite into low Earth orbit, and there was no budget for another H-IIA launch. Finally, in order to be able to perform the tests during the lifetime of the European Artemis satellite (since 2014, sold to Avanti Communications to exploit its Ka, S, and L-band payloads), OICETS was successfully launched on a Dnepr rocket (OiCETS riding on a decommissioned SS-18 ICBM in place of the warheads).
The satellite was decommissioned and its mission terminated on 24 September 2009 at 05:48 UTC.


Rayleigh interferometer

The Rayleigh interferometer employs two beams of light from a single source, and determines the difference in optical path length between the two paths using interference between the two beams when they are recombined following traversal of the paths. An example is shown in the figure. Light from a source (top) is collimated by a lens and split into two beams using slits. The beams are sent through two different paths and pass through compensating plates. They are brought to a focus by a second lens (bottom) where an interference pattern is observed to determine the optical path difference in terms of wavelengths of the light.
Advantages and disadvantages.
The advantage of the Rayleigh interferometer is its simple construction. Its drawbacks are (i) it requires a point or line source of light for good fringe visibility, and (ii) the fringes must be viewed with high magnification.


Tanzanian units of measurement

A number of units of measurement have been used in Tanzania to measure length, mass, capacity, etc. The metric system was adopted in Tanzania from 1967 to 1969.
System before metric system.
A number of units were used.
Zanzibar.
Several units were used in Zanzibar
Length.
One ohra was equal to 0.571 m (22.48 in).
Weight.
One bazla was equal to 15.525 kg (32.226 lb). One mane was equal to 2.0071 lb. One franzella of 36 rotoli was equal to 35.2822 lb.
Capacity.
One djezla was equal to 257.4 l (7.305 bushels).


Jill DeMatteis

Jill Marie Montaquila DeMatteis is an American statistician specializing in survey methodology. She has worked as a statistician in the US Bureau of Labor Statistics, and is a research associate professor at the University of Maryland, College Park and a vice president in the Statistics and Evaluation Sciences Group of Westat.
Education and career.
DeMatteis graduated from Ashland College in 1989, majoring in mathematics and economics; she credits Ashland mathematics professor Alan G. Poorman with her decision to study mathematics there. After earning a master's degree in statistics from Miami University in Ohio, she became a Bureau of Labor Statistics researcher from 1991 to 1995.
She moved to Westat in 1995 and returned to graduate study, completing her Ph.D. at American University in 1998. Her dissertation, "All-Cases Imputation Variance Estimator: A New Approach to Variance Estimation for Imputed Data", was supervised by Robert Jernigan.
Service and recognition.
DeMatteis was president of the Washington Statistical Society for 2006–2007, chaired the Survey Research Methods Section of the American Statistical Association (ASA) in 2013, and chaired the ASA Government Statistics Section in 2014.
She was named a Fellow of the American Statistical Association in 2008. In 2016 the Government Statistics Section gave her their Pat Doyle Award.


IRIG timecode

Inter-range instrumentation group timecodes, commonly known as IRIG timecode, are standard formats for transferring timing information. Atomic frequency standards and GPS receivers designed for precision timing are often equipped with an IRIG output. The standards were created by the Tele Communications Working Group of the U.S. military's Inter-Range Instrumentation Group (IRIG), the standards body of the Range Commanders Council. Work on these standards started in October 1956, and the original standards were accepted in 1960.
The original formats were described in IRIG Document 104-60, later revised and reissued in August 1970 as IRIG Document 104-70, upgraded later that year as the IRIG Document to the status of a Standard, IRIG Standard 200-70. The latest version of the Standard is IRIG Standard 200-16 from August 2016.
Timecodes.
The different timecodes defined in the Standard have alphabetic designations. A, B, D, E, G, and H are the standards currently defined by IRIG Standard 200-04.
C was in the original specification, but was replaced by H.
The main difference between codes is their rate, which varies between one pulse per minute and 10,000 pulses per second.
IRIG Code B Calculation:

Bit rate = 100 Hz = 100 × (1 / second) = 100 / second = 100 / 1000 ms = 1 / 10ms

Bit time = 1 / (Bit rate) = 1 / (1 / 10 ms) = 10 ms

There are 100 Bits per frame.

Frame time = (Bits per frame) × (Bit time) = 100 × 10 ms = 1000 ms = 1 second

Frame rate = 1 / (Frame time) = 1 / 1 second = 1 Hz

The bits are modulated on a carrier. A three-digit suffix specifies the type and frequency of the carrier, and which optional information is included:
Binary-coded decimal (BCD) day of year, hours, minutes, and (for some formats) seconds and fractions are always included. Optional components are:
The recognized signal identification numbers for each format according to the standard 200-04 consist of:
Thus the complete signal identification number consists of one letter and three digits. For example, the signal designated as B122 is deciphered as follows: Format B, Sine wave (amplitude modulated), 1 kHz carrier, and Coded expressions BCDTOY.
The most commonly used of the standards is IRIG B, then IRIG A, then probably IRIG G. Timecode formats directly derived from IRIG H are used by NIST radio stations WWV, WWVH and WWVB.
For example, one of the most common formats, IRIG B122:
Timecode structure.
IRIG timecode is made up of repeating frames, each containing 60 or 100 bits. The bits are numbered from 0 through 59 or 99.
At the start of each bit time, the IRIG timecode enables a signal (sends a carrier, raises the DC signal level, or transmits Manchester 1 bits). The signal is disabled (carrier attenuated at least 3×, DC signal level lowered, or Manchester 0 bits transmitted), at one of three times during the bit interval:
Bit 0 is the frame marker bit Pr. Every 10th bit starting with bit 9, 19, 29, ... 99 is also a marker bit, known as position identifiers P1, P2, ..., P9, P0. Thus, two marker bits in a row (P0 followed by Pr) marks the beginning of a frame. The frame encodes the time of the leading edge of the frame marker bit.
All other bits are data bits, which are transmitted as binary 0 if they have no other assigned purpose.
Generally, groups of 4 bits are used to encode BCD digits. Bits are assigned little-endian within fields.
In IRIG G, bits 50–53 encode hundredths of seconds, and the years are encoded in bits 60–68.
Not all formats include all fields. Obviously those formats with 60-bit frames omit the straight binary seconds fields, and digits representing divisions less than one frame time (everything below hours, in the case of IRIG D) are always transmitted as 0.
No parity or check bits are included. Error detection can be achieved by comparing consecutive frames to see if they encode consecutive timestamps.
Unassigned 9-bit fields between consecutive marker bits are available for user-defined "control functions". For example, the IEEE 1344 standard defines functions for bits 60–75.
IRIG J timecode.
IRIG standard 212-00 defines a different time-code, based on RS-232-style asynchronous serial communication.
The timecode consists of ASCII characters, each transmitted as 10 bits:
The on-time marker is the leading edge of the first start bit.
IRIG J-1 timecode consists of 15 characters (150 bit times), sent once per second at a baud rate of 300 or greater:
 <SOH>DDD:HH:MM:SS<CR><LF>
At the end of the timecode, the serial line is idle until the start of the next code. There is no idle time between other characters.
IRIG J-2 timecode consists of 17 characters (170 bit times), sent 10 times per second at a baud rate of 2400 or greater:
 <SOH>DDD:HH:MM:SS.S<CR><LF>
This is the same, except that tenths of seconds are included.
The full-timecode specification is of the form "IRIG J-"xy"", where "x" denotes the variant, and "y" denotes a baud rate of 75×2"y".
Normally used combinations are J-12 through J-14 (300, 600, and 1200 baud), and J-25 through J-29 (2400 through 38400 baud).


676 Melitta

676 Melitta is a minor planet orbiting the Sun. It is classified as a main belt asteroid. The name, "Melitta", is the Attic Greek form of the name "Melissa"—a reference both to the nymph of ancient Greek mythology, and to the minor planet's discoverer, Melotte.


9969 Braille

9969 Braille, provisional designation , is an eccentric, rare-type and elongated asteroid from the innermost regions of the asteroid belt, classified as Mars-crosser and slow rotator, approximately 1–2 kilometers in diameter. It was discovered in 1992, by astronomers at Palomar observatory and later named after Louis Braille, the inventor of the writing system for the blind. It was photographed in closeup by the spacecraft Deep Space 1 in 1999, but a malfunction resulted in indistinct images.
Discovery and naming.
Discovered on May 27, 1992, by E. F. Helin and K. J. Lawrence working at the Palomar observatory as part of NASA's Planet-Crossing Asteroid Survey, it was given the provisional designation . Later, it was renamed Braille in honour of Louis Braille as suggested by Kennedy Space Center software engineer Kerry Babcock in The Planetary Society's contest titled "Name That Asteroid". The official naming citation was published by the Minor Planet Center on 28 July 1999 ().
Orbit.
Braille has an unusually inclined orbit, and belongs to the somewhat rare class of asteroids known as Mars-crossing asteroids. Simulations of its orbit by scientists of the Deep Space 1 project predict that it will evolve into an Earth-crossing orbit in about 4000 years. Although its closest approach to the Sun is closer than Mars orbit, its highly elliptical orbit takes it almost half-way to Jupiter at its apoapsis, and as such its semi-major axis is too large for it to be classified as an Amor asteroid.
Physical characteristics.
Braille is a Q-type asteroid, composed mostly of olivine and pyroxene. Early ground-based observations had suggested that it could have been a V-type asteroid with similarities of composition between it and the much larger 4 Vesta. The asteroid is irregularly shaped, measuring approximately 2.1 km × 1 km × 1 km.
Exploration.
Detailed information about Braille comes primarily from the Deep Space 1 probe, which passed within 26 km of the asteroid on July 29, 1999, and from extensive ground based observations done in conjunction with the mission. By the time Deep Space 1 reached Braille, its ultraviolet spectrometer had failed, but it did return two CCD images of medium resolution and three infrared spectra during the encounter. However, although the probe came within 26 km of Braille, the images and spectra were taken from an approximate distance of 14 000 km, due to problems with the tracking system.
The main purpose of the Deep Space 1 mission was technology testing, but the encounter with Braille was of strong scientific value. No lone asteroid as small as Braille had previously been observed from such a short distance.


Huib Bakker

Huib Johan Bakker (born 2 March 1965) is a Dutch physicist working in the field of ultrafast spectroscopy. He has been president of research institute AMOLF since 1 February 2016.
Career.
Bakker was born on 2 March 1965 in Haarlem. He studied physical chemistry at the Vrije Universiteit Amsterdam, and obtained his master's degree in 1987. He subsequently became a PhD student under Ad Lagendijk at the AMOLF research institute. Bakker received his doctorate cum laude in 1991 with a thesis titled:"Time-resolved vibrational spectroscopy with picosecond infrared pulses". Between 1991 and 1994 he was a scientific assistant at the Institute of Semiconductor Technologies of RWTH Aachen University in Germany.
In 1995 Bakker returned to the Netherlands to become scientific group leader at AMOLF. Six years later he started as professor of Ultrafast Spectroscopy of Molecules in the Condensed Phase at the University of Amsterdam. At AMOLF Bakker is group leader of research on ultrafast spectroscopy. In 2003 he became head of the department of molecular nanophysics. In his research at AMOLF Bakker has been founder of a technique which uses special non-linear spectroscopics, which helps researchers in determining the molecular mobility and structure of water in complex systems.
Bakker became adjunct director of AMOLF on 1 September 2015. On 1 February 2016 he succeeded Vinod Subramaniam as director, who became rector-magnificus of the Vrije Universiteit Amsterdam.
Awards and honors.
In 2005 Bakker received the gold medal of the Royal Netherlands Chemical Society. Bakker was elected a member of the Royal Netherlands Academy of Arts and Sciences in 2015. The Academy called him "a renowned expert on the molecular properties of water and ice".


Thundering herd problem

In computer science, the thundering herd problem occurs when a large number of processes or threads waiting for an event are awoken when that event occurs, but only one process is able to handle the event. When the processes wake up, they will each try to handle the event, but only one will win. All processes will compete for resources, possibly freezing the computer, until the herd is calmed down again.
Mitigation.
The Linux-kernel will serialize responses for requests to a single file descriptor, so only one thread (process) is woken up. For epoll() in Linux 4.5 kernel version was added EPOLLEXCLUSIVE flag, thus several epoll sets (different threads or different processes) may wait on same resource and only one set will be woken up. For certain workloads this flag can give significant processing time reduction.
Similarly in Microsoft Windows, I/O completion ports can mitigate the thundering herd problem, as they can be configured such that only one of the threads waiting on the completion port is woken up when an event occurs.
In systems which rely on a backoff mechanism (e.g. exponential backoff), the clients will retry failed calls, by waiting a specific amount of time between consecutive retries. In order to avoid the thundering herd problem, jitter can be purposefully introduced, in order to break the synchronization across the clients thereby avoiding collisions. In this approach, randomness is added to the wait intervals between retries, so that clients are no longer synchronized.


Fokker periodicity block

Fokker periodicity blocks are a concept in tuning theory used to mathematically relate musical intervals in just intonation to those in equal tuning. They are named after Adriaan Daniël Fokker. These are included as the primary subset of what Erv Wilson refers to as constant structures, where "each interval occurs always subtended by the same number of steps".
The basic idea of Fokker's periodicity blocks is to represent just ratios as points on a lattice, and to find vectors in the lattice which represent very small intervals, known as commas. Treating pitches separated by a comma as equivalent "folds" the lattice, effectively reducing its dimension by one; mathematically, this corresponds to finding the quotient group of the original lattice by the sublattice generated by the commas.
For an "n"-dimensional lattice, identifying "n" linearly independent commas reduces the dimension of the lattice to zero, meaning that the number of pitches in the lattice is finite; mathematically, its quotient is a finite abelian group. This zero-dimensional set of pitches is a periodicity block. Frequently, it forms a cyclic group, in which case identifying the "m" pitches of the periodicity block with "m"-equal tuning gives equal tuning approximations of the just ratios that defined the original lattice.
Note that octaves are usually ignored in constructing periodicity blocks (as they are in scale theory generally) because it is assumed that for any pitch in the tuning system, all pitches differing from it by some number of octaves are also available in principle. In other words, all pitches and intervals can be considered as residues modulo octave. This simplification is commonly known as octave equivalence.
Definition of periodicity blocks.
Let an "n"-dimensional lattice (i.e. integer grid) embedded in "n"-dimensional space have a numerical value assigned to each of its nodes, such that moving within the lattice in one of the cardinal directions corresponds to a shift in pitch by a particular interval. Typically, "n" ranges from one to three. Simultaneously the two-dimensional case, the lattice is a square lattice. In the 3-D case, the lattice is cubic.
Examples of such lattices are the following ("x", "y", "z" and "w" are integers):
Once the lattice and its labeling is fixed, one chooses "n" nodes of the lattice other than the origin whose values are close to either 1 or 2.
The vectors from the origin to each one of these special nodes are called "unison vectors". These vectors define a sublattice of the original lattice, which has a fundamental domain that in the two-dimensional case is a parallelogram bounded by unison vectors and their shifted copies, and in the three-dimensional case is a parallelepiped. These domains form the tiles in a tessellation of the original lattice.
The tile has an area or volume given by the absolute value of the determinant of the matrix of unison vectors: i.e. in the 2-D case if the unison vectors are u and v, such that formula_1 and formula_2 then the area of a 2-D tile is
Each tile is called a Fokker periodicity block. The area of each block is always a natural number equal to the number of nodes falling within each block.
Examples.
Example 1: Take the 2-dimensional lattice of perfect fifths (ratio 3/2) and just major thirds (ratio 5/4). Choose the commas 128/125 (the diesis, the distance by which three just major thirds fall short of an octave, about 41 cents) and 81/80 (the syntonic comma, the difference between four perfect fifths and a just major third, about 21.5 cents). The result is a block of twelve, showing how twelve-tone equal temperament approximates the ratios of the 5-limit.
Example 2: However, if we were to reject the diesis as a unison vector and instead choose the difference between five major thirds (minus an octave) and a fourth, 3125/3072 (about 30 cents), the result is a block of 19, showing how 19-TET approximates ratios of the 5-limit.
Example 3: In the 3-dimensional lattice of perfect fifths, just major thirds, and "just minor sevenths" (ratio 7/4), the identification of the syntonic comma, the septimal kleisma (225/224, about 8 cents), and the ratio 1029/1024 (the difference between three septimal whole tones and a perfect fifth, about 8.4 cents) results in a block of 31, showing how 31-TET approximates ratios of the 7-limit.
Mathematical characteristics of periodicity blocks.
The periodicity blocks form a secondary, oblique lattice, superimposed on the first one. This lattice may be given by a function φ:
which is really a linear combination:
where point ("x"0, "y"0) can be any point, preferably not a node of the primary lattice, and preferably so that points φ(0,1), φ(1,0) and φ(1,1) are not any nodes either.
Then membership of primary nodes within periodicity blocks may be tested analytically through the inverse φ function:
Let
then let the pitch "B"("x","y") belong to the scale "M""B" iff formula_10 i.e.
For the one-dimensional case:
where "L" is the length of the unison vector,
For the three-dimensional case,
where formula_18 is the determinant of the matrix of unison vectors.


2208 Pushkin


2852 Declercq


Michelson interferometer

The Michelson interferometer is a common configuration for optical interferometry and was invented by Albert Abraham Michelson. Using a beam splitter, a light source is split into two arms. Each of those light beams is reflected back toward the beamsplitter which then combines their amplitudes using the superposition principle. The resulting interference pattern that is not directed back toward the source is typically directed to some type of photoelectric detector or camera. For different applications of the interferometer, the two light paths can be with different lengths or incorporate optical elements or even materials under test.
The Michelson interferometer (among other interferometer configurations) is employed in many scientific experiments and became well known for its use by Albert Michelson and Edward Morley in the famous Michelson–Morley experiment (1887) in a configuration which would have detected the earth's motion through the supposed luminiferous aether that most physicists at the time believed was the medium in which light waves propagated. The null result of that experiment essentially disproved the existence of such an aether, leading eventually to the special theory of relativity and the revolution in physics at the beginning of the twentieth century. In 2015, another application of the Michelson interferometer, LIGO, made the first direct observation of gravitational waves. That observation confirmed an important prediction of general relativity, validating the theory's prediction of space-time distortion in the context of large scale cosmic events (known as strong field tests).
Configuration.
A Michelson interferometer consists minimally of mirrors "M1" & "M2" and a beam splitter "M".
In Fig 2, a source "S" emits light that hits the beam splitter (in this case, a plate beamsplitter) surface "M" at point "C". "M" is partially reflective, so part of the light is transmitted through to point "B" while some is reflected in the direction of "A". Both beams recombine at point "C' "to produce an interference pattern incident on the detector at point "E" (or on the retina of a person's eye). If there is a slight angle between the two returning beams, for instance, then an imaging detector will record a sinusoidal "fringe pattern" as shown in Fig. 3b. If there is perfect spatial alignment between the returning beams, then there will not be any such pattern but rather a constant intensity over the beam dependent on the differential pathlength; this is difficult, requiring very precise control of the beam paths.
Fig. 2 shows use of a coherent (laser) source. Narrowband spectral light from a discharge or even white light can also be used, however to obtain significant interference contrast it is required that the differential pathlength is reduced below the coherence length of the light source. That can be only micrometers for white light, as discussed below.
If a lossless beamsplitter is employed, then one can show that optical energy is conserved. At every point on the interference pattern, the power that is "not" directed to the detector at "E" is rather present in a beam (not shown) returning in the direction of the source.
As shown in Fig. 3a and 3b, the observer has a direct view of mirror "M1" seen through the beam splitter, and sees a reflected image "M'2" of mirror "M2". The fringes can be interpreted as the result of interference between light coming from the two virtual images "S'1" and "S'2" of the original source "S". The characteristics of the interference pattern depend on the nature of the light source and the precise orientation of the mirrors and beam splitter. In Fig. 3a, the optical elements are oriented so that "S'1" and "S'2" are in line with the observer, and the resulting interference pattern consists of circles centered on the normal to "M1" and "M'2" (fringes of equal inclination). If, as in Fig. 3b, "M1" and "M'2" are tilted with respect to each other, the interference fringes will generally take the shape of conic sections (hyperbolas), but if "M1" and "M'2" overlap, the fringes near the axis will be straight, parallel, and equally spaced (fringes of equal thickness). If S is an extended source rather than a point source as illustrated, the fringes of Fig. 3a must be observed with a telescope set at infinity, while the fringes of Fig. 3b will be localized on the mirrors.
Source bandwidth.
White light has a tiny coherence length and is difficult to use in a Michelson (or Mach–Zehnder) interferometer. Even a narrowband (or "quasi-monochromatic") spectral source requires careful attention to issues of chromatic dispersion when used to illuminate an interferometer. The two optical paths must be practically equal for all wavelengths present in the source. This requirement can be met if both light paths cross an equal thickness of glass of the same dispersion. In Fig. 4a, the horizontal beam crosses the beam splitter three times, while the vertical beam crosses the beam splitter once. To equalize the dispersion, a so-called compensating plate identical to the substrate of the beam splitter may be inserted into the path of the vertical beam. In Fig. 4b, we see using a cube beam splitter already equalizes the pathlengths in glass. The requirement for dispersion equalization is eliminated by using extremely narrowband light from a laser.
The extent of the fringes depends on the coherence length of the source. In Fig. 3b, the yellow sodium light used for the fringe illustration consists of a pair of closely spaced lines, D1 and D2, implying that the interference pattern will blur after several hundred fringes. Single longitudinal mode lasers are highly coherent and can produce high contrast interference with differential pathlengths of millions or even billions of wavelengths. On the other hand, using white (broadband) light, the central fringe is sharp, but away from the central fringe the fringes are colored and rapidly become indistinct to the eye.
Early experimentalists attempting to detect the earth's velocity relative to the supposed luminiferous aether, such as Michelson and Morley (1887) and Miller (1933), used quasi-monochromatic light only for initial alignment and coarse path equalization of the interferometer. Thereafter they switched to white (broadband) light, since using white light interferometry they could measure the point of "absolute phase" equalization (rather than phase modulo 2π), thus setting the two arms' pathlengths equal. More importantly, in a white light interferometer, any subsequent "fringe jump" (differential pathlength shift of one wavelength) would always be detected.
Applications.
The Michelson interferometer configuration is used in a number of different applications.
Fourier transform spectrometer.
Fig. 5 illustrates the operation of a Fourier transform spectrometer, which is essentially a Michelson interferometer with one mirror movable. (A practical Fourier transform spectrometer would substitute corner cube reflectors for the flat mirrors of the conventional Michelson interferometer, but for simplicity, the illustration does not show this.) An interferogram is generated by making measurements of the signal at many discrete positions of the moving mirror. A Fourier transform converts the interferogram into an actual spectrum. Fourier transform spectrometers can offer significant advantages over dispersive ("i.e." grating and prism) spectrometers under certain conditions. (1) The Michelson interferometer's detector in effect monitors all wavelengths simultaneously throughout the entire measurement. When using a noisy detector, such as at infrared wavelengths, this offers an increase in signal to noise ratio while using only a single detector element; (2) the interferometer does not require a limited aperture as do grating or prism spectrometers, which require the incoming light to pass through a narrow slit in order to achieve high spectral resolution. This is an advantage when the incoming light is not of a single spatial mode. For more information, see Fellgett's advantage.
Twyman–Green interferometer.
The Twyman–Green interferometer is a variation of the Michelson interferometer used to test small optical components, invented and patented by Twyman and Green in 1916. The basic characteristics distinguishing it from the Michelson configuration are the use of a monochromatic point light source and a collimator. Michelson (1918) criticized the Twyman–Green configuration as being unsuitable for the testing of large optical components, since the available light sources had limited coherence length. Michelson pointed out that constraints on geometry forced by the limited coherence length required the use of a reference mirror of equal size to the test mirror, making the Twyman–Green impractical for many purposes. Decades later, the advent of laser light sources answered Michelson's objections.
The use of a figured reference mirror in one arm allows the Twyman–Green interferometer to be used for testing various forms of optical component, such as lenses or telescope mirrors. Fig. 6 illustrates a Twyman–Green interferometer set up to test a lens. A point source of monochromatic light is expanded by a diverging lens (not shown), then is collimated into a parallel beam. A convex spherical mirror is positioned so that its center of curvature coincides with the focus of the lens being tested. The emergent beam is recorded by an imaging system for analysis.
Laser unequal path interferometer.
The "LUPI" is a Twyman–Green interferometer that uses a coherent laser light source. The high coherence length of a laser allows unequal path lengths in the test and reference arms and permits economical use of the Twyman–Green configuration in testing large optical components. A similar scheme has been used by Tajammal M in his PhD thesis (Manchester University UK, 1995) to balance two arms of an LDA system. This system used fibre optic direction coupler.
Stellar measurements.
The Michelson stellar interferometer is used for measuring the diameter of stars. In 1920, Michelson and Francis G. Pease used it to measure the diameter of Betelgeuse, the first time the diameter of a star other than the sun was measured.
Gravitational wave detection.
Michelson interferometry is the leading method for the direct detection of gravitational waves. This involves detecting tiny strains in space itself, affecting two long arms of the interferometer unequally, due to a strong passing gravitational wave. In 2015 the first detection of gravitational waves was accomplished using the two Michelson interferometers, each with 4 km arms, which comprise the Laser Interferometer Gravitational-Wave Observatory. This was the first experimental validation of gravitational waves, predicted by Albert Einstein's General Theory of Relativity. With the addition of the Virgo interferometer in Europe, it became possible to calculate the direction from which the gravitational waves originate, using the tiny arrival-time differences between the three detectors. In 2020, India was constructing a fourth Michelson interferometer for gravity wave detection.
Miscellaneous applications.
Fig. 7 illustrates use of a Michelson interferometer as a tunable narrow band filter to create dopplergrams of the Sun's surface. When used as a tunable narrow band filter, Michelson interferometers exhibit a number of advantages and disadvantages when compared with competing technologies such as Fabry–Pérot interferometers or Lyot filters. Michelson interferometers have the largest field of view for a specified wavelength, and are relatively simple in operation, since tuning is via mechanical rotation of waveplates rather than via high voltage control of piezoelectric crystals or lithium niobate optical modulators as used in a Fabry–Pérot system. Compared with Lyot filters, which use birefringent elements, Michelson interferometers have a relatively low temperature sensitivity. On the negative side, Michelson interferometers have a relatively restricted wavelength range, and require use of prefilters which restrict transmittance. The reliability of Michelson interferometers has tended to favor their use in space applications, while the broad wavelength range and overall simplicity of Fabry–Pérot interferometers has favored their use in ground-based systems.
Another application of the Michelson interferometer is in optical coherence tomography (OCT), a medical imaging technique using low-coherence interferometry to provide tomographic visualization of internal tissue microstructures. As seen in Fig. 8, the core of a typical OCT system is a Michelson interferometer. One interferometer arm is focused onto the tissue sample and scans the sample in an X-Y longitudinal raster pattern. The other interferometer arm is bounced off a reference mirror. Reflected light from the tissue sample is combined with reflected light from the reference. Because of the low coherence of the light source, interferometric signal is observed only over a limited depth of sample. X-Y scanning therefore records one thin optical slice of the sample at a time. By performing multiple scans, moving the reference mirror between each scan, an entire three-dimensional image of the tissue can be reconstructed. Recent advances have striven to combine the nanometer phase retrieval of coherent interferometry with the ranging capability of low-coherence interferometry.
Others applications include delay line interferometer which convert phase modulation into amplitude modulation in DWDM networks, the characterization of high-frequency circuits., and low-cost THz power generation.
Atmospheric and space applications.
The Michelson Interferometer has played an important role in studies of the upper atmosphere, revealing temperatures and winds, employing both space-borne, and ground-based instruments, by measuring the Doppler widths and shifts in the spectra of airglow and aurora. For example, the Wind Imaging Interferometer, WINDII, on the Upper
Atmosphere Research Satellite, UARS, (launched on September 12, 1991) measured the global wind and temperature patterns from 80 to 300 km by using the visible airglow emission from these altitudes as a target and employing optical Doppler interferometry to measure the small wavelength shifts of the narrow atomic and molecular airglow emission lines induced by the
bulk velocity of the atmosphere carrying the emitting species. The instrument was an all-glass field-widened achromatically and thermally compensated phase-stepping Michelson interferometer, along with a bare CCD detector that imaged the airglow limb through the interferometer. A sequence of phase-stepped images was processed to derive the wind velocity for two orthogonal view directions, yielding the horizontal wind vector.
The principle of using a polarizing Michelson Interferometer as a narrow band filter was first described by Evans who developed a birefringent photometer where the incoming light is split into two orthogonally polarized components by a polarizing beam splitter, sandwiched between two halves of a Michelson cube. This led to the first polarizing wide-field Michelson interferometer described by Title and Ramsey which was used for solar observations; and led to the development of a refined instrument applied to measurements of oscillations in the sun's atmosphere, employing a network of observatories around the Earth known as the Global Oscillations Network Group (GONG).
The Polarizing Atmospheric Michelson Interferometer, PAMI, developed by Bird et al., and discussed in "Spectral Imaging of the Atmosphere", combines the polarization tuning technique of Title and Ramsey with the Shepherd "et al." technique of deriving winds and temperatures from emission rate measurements at sequential path differences, but the scanning system used by PAMI is much simpler than the moving mirror systems in that it has no internal moving parts, instead scanning with a polarizer external to the interferometer. The PAMI was demonstrated in an observation campaign where its performance was compared to a Fabry–Pérot spectrometer, and employed to measure E-region winds.
More recently, the Helioseismic and Magnetic Imager (HMI), on the Solar Dynamics Observatory, employs two Michelson Interferometers with a polarizer and other tunable elements, to study solar variability and to characterize the Sun's interior along with the various components of magnetic activity. HMI takes high-resolution measurements of the longitudinal and vector magnetic field over the entire visible disk thus extending the capabilities of its predecessor, the SOHO's MDI instrument (See Fig. 9). HMI produces data to determine the interior sources and mechanisms of solar variability and how the physical processes inside the Sun are related to surface magnetic field and activity. It also produces data to enable estimates of the coronal magnetic field for studies of variability in the extended solar atmosphere. HMI observations will help establish the relationships between the internal dynamics and magnetic activity in order to understand solar variability and its effects.
In one example of the use of the MDI, Stanford scientists reported the detection of several sunspot regions in the deep interior of the Sun, 1–2 days before they appeared on the solar disc. The detection of sunspots in the solar interior may thus provide valuable warnings about upcoming surface magnetic activity which could be used to improve and extend the predictions of space weather forecasts.
Technical topics.
Step-phase interferometer.
This is a Michelson interferometer in which the mirror in one arm is replaced with a Gires–Tournois etalon. The highly dispersed wave reflected by the Gires–Tournois etalon interferes with the original wave as reflected by the other mirror. Because the phase change from the Gires–Tournois etalon is an almost step-like function of wavelength, the resulting interferometer has special characteristics. It has an application in fiber-optic communications as an optical interleaver.
Both mirrors in a Michelson interferometer can be replaced with Gires–Tournois etalons. The step-like relation of phase to wavelength is thereby more pronounced, and this can be used to construct an asymmetric optical interleaver.
Phase-conjugating interferometry.
The reflection from phase-conjugating mirror of two light beams inverses their phase difference
formula_1 to the opposite one formula_2. For this reason the interference pattern in twin-beam interferometer changes drastically. Compared to conventional Michelson interference curve with period of half-wavelength formula_3:
formula_4,
where formula_5 is second-order correlation function, the interference curve in phase-conjugating interferometer
has much longer period defined by frequency shift
formula_6 of reflected beams:
formula_7,
where visibility curve is nonzero when optical path difference
formula_8 exceeds coherence length of light beams.
The nontrivial features of phase fluctuations in optical phase-conjugating mirror had been studied via Michelson interferometer with two independent PC-mirrors
. The phase-conjugating Michelson interferometry is a promising technology for coherent summation of laser amplifiers
Constructive interference in an array containing formula_9 beamsplitters of formula_10 laser beams synchronized by
phase conjugation
may increase the brightness of amplified beams as formula_11.


Nicaraguan units of measurement

A number of units of measurement were used in Nicaragua to measure measurements in mass, area, volume, etc. In Nicaragua, the metric system was adopted in 1910, and has been compulsory since 1912, by a joint convention between Costa Rica, Guatemala, Honduras, Nicaragua and El Salvador.
Pre-metric units.
Before the metric system, a number of modified Spanish (i.e. Spanish Castilian), English and local units were used.
Mass.
Several units were used to measure mass in the above five countries. Some of these units are given below:
1 caja = 16 kg
1 fanega = 92 kg
1 carga = 161 kg
Area.
Several units were used to measure area in these countries. One manzana was equal to 10,000 square varas or 6987.4 m2. (A vara was an obsolete Spanish unit of length equal to 0.8359 m.) One caballeria was equal to 64 manzanas.
Volume.
Several units were used to measure volume in these countries. One botella was equal to 0.63 to 0.67 litres. One cajuela was equal to 16.6 litres. However the capacity of one cuartillo is very variable.


Angela Dale

Angela Dale (born 1945) is a British social scientist and statistician whose research has involved the secondary analysis of government survey data, and the study of women in the workforce. Formerly Deputy Director of the Social Statistics Research Unit of City, University of London, and Professor of Quantitative Research and Director of the Cathie Marsh Centre for Census and Survey Research at the University of Manchester, she is now a professor emerita at Manchester.
Selected publications.
Dale is an author of the books;
She is an editor of
She has also published highly cited journal papers on women in the workforce including
Recognition.
Dale is a Fellow of the Academy of Social Sciences. She was named to the Order of the British Empire in the 2006 New Year Honours "for services to social science". In 2006, Dale won the West Medal of the Royal Statistical Society, given "for outstanding contributions to the development or communication of official statistics".


Indian Police Service Limited Competitive Examination

To face the shortage of Indian Police Service officers in India as a result the high attrition in the Indian Police Service, the Ministry of Home Affairs proposed the formation of Indian Police Service Limited Competitive Examination to be conducted by UPSC. IPS Limited Competitive Examination was held for the first time in 2012. This is in addition to the Civil Services Examination conducted by UPSC itself, for recruitment to the various civil services including Indian Police Service.The Central Administrative Tribunal(CAT) has struck down the examination following the challenge by some state cadre police officers. Consequent to the CAT verdict, UPSC has withheld the declaration of final results of 2012 examination. Now the Ministry of Home Affairs is trying to sort out the legal matters as soon as possible.
Eligibility Conditions.
(a)The candidate must hold a degree of any of Universities incorporated by an Act of the Central or State Legislature in India or other educational institutions established by an Act of Parliament or declared to be deemed as a University Under Section-3 of the University Grants Commission Act, 1956, or possess an equivalent qualification.
(b) A candidate must not have attained the age of 32 years for General Category, 35 years for Other Backward Classes category candidates and 37 years for candidates belonging to a Scheduled Caste or Scheduled Tribe.
Part B - Main Examination - Optional
Paper-I
One of the Indian Languages to be selected by the candidate from the 22 languages included in the VIIIth Schedule to the Constitution (Qualifying Paper) am during the job
300 Marks
Paper-II
English (Qualifying Paper)
300 Marks
Paper-III
Essay [in the medium you choose]
Papers
Papers VI, VII, VIII & IX X
Any two subjects (each having 2 papers) to be selected from the prescribed optional subjects (300 marks for each paper)
1200 Mark
Scheme of Examination.
The Examination will comprise two components viz. Written Examination and Interview for Personality Test.
Note 3: The objective from papers will be qualifying in nature.
Brief Syllabus.
Paper I:- General Studies covering Current affairs, History of India, Geography of India and the world, Indian polity and Governance, Economic and social development, Environmental issues, General Science
get paper II :- Aptitude test comprising Comprehension, Interpersonal skills, Logical reasoning and analytical ability, Decision making and problem-solving, General mental ability, Basic numeracy, and English Language Comprehension skills
Paper III :- English Language paper. This paper would be of Matriculation standard and qualifying in nature only. Its marks will not be counted for the preparation of merit ranking.
Paper IV :- Essay paper. It will comprise two essays, one on the security aspect and the other on the various developmental aspects of the society.
Paper V:- General Studies paper covering various aspects like Elementary Principles of Public Law, State Policy, Fundamental Rights, Human Rights, Disaster Management, National Security, etc.
Part B
PAPERS OF DESCRIPTIVE TYPE
Paper III : English (200 marks / 3 hours duration):- This will be a qualifying test only
of Matriculation or equivalent standard.
The aim of the paper is to test the candidate’s ability to read and understand serious
discursive prose, and to express his ideas clearly and correctly, in English.
The pattern of questions would be broad as follows (indicative only) :—
UPSC Prelims Syllabus
Syllabus for GS Paper (Prelims Paper I)
Current events of national and international importance.
History of India and Indian National Movement.
Indian and World Geography-Physical, Social, Economic Geography of India and the World.
Indian Polity and Governance – Constitution, Political System, Panchayati Raj, Public Policy, Rights Issues, etc.
Economic and Social Development – Sustainable Development, Poverty, Inclusion, Demographics, Social Sector initiatives, etc.
General issues on Environmental Ecology, Biodiversity and Climate Change – that do not require subject specialisation.
General Science
Syllabus for CSAT Paper (Prelims Paper-II)
Comprehension
Interpersonal skills including communication skills
Logical reasoning and analytical ability
Decision-making and problem solving
General mental ability
Basic numeracy (numbers and their relations, orders of magnitude, etc.) (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc. – Class X level)
Note I : Answer all questions in this paper will have to be attempted in English only.
Paper IV: Essay ( 200 Marks/ 3 hours duration)
Candidates will be required to write two Essays. One topic will pertain to Indian Society/
politics/ Economy/Development, Growth, and related aspects. The other topic will pertain
to security and related matters. Candidates will be expected to keep close to the
subject of the essay to arrange their ideas in an orderly fashion and to write concisely.
Credit will be given for effective and exact expression.
Paper V: General Studies (200 Marks/ 3 hours duration)
The questions will be such as to test a candidate’s awareness of a variety of subjects
and are likely to test the candidate’s basic understanding of all relevant issues, and
the ability to analyze and take a view on conflicting socio-economic goals, objectives and
demands. The candidates must give relevant, meaningful and succinct answers.
Note: This paper can be answered by the Candidates either in English or in Hindi.
Attempting answers in any other language or use of ‘mixed’ language (i.e. partly in English and partly in Hindi) is not permissible.
Syllabus:
a) A brief idea about the History and Geography of India.
b) Constitution of India and Indian Polity: This part will include questions on the Constitution of India, as well as all constitutional, legal, administrative and other issues emerging from the politico-administrative system prevalent in the country.
c) Current National Issues and Topics of Social Relevance -
This part is intended to test the Candidate’s awareness of current national issues and topics of social relevance in present-day India, such as the following :


Eskaton

Eskaton is a defunct vanity record label created by Coil, exclusively for albums put out by the group and their friends. Its brother labels are Threshold House and Chalice.
The record label is often associated with the symbol of the "Chaos Cross" and the "Twisted Chaos Cross", symbols which have appeared on several Eskaton releases, such as "Gold Is The Metal with the Broadest Shoulders".
Chaos Cross.
The symbol of the chaos cross was used almost exclusively in the times of Coil's side projects. It is a dominant symbol which can be found on a number of releases and merchandise.


4942 Munroe

4942 Munroe, provisional designation , is an asteroid from the inner regions of the asteroid belt, approximately 3 kilometers in diameter. It was discovered on 24 February 1987, by Belgian astronomer Henri Debehogne at ESO's La Silla Observatory in northern Chile, and later named after American cartoonist and former NASA roboticist Randall Munroe.
Orbit and classification.
"Munroe" orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 3 months (1,193 days). Its orbit has an eccentricity of 0.14 and an inclination of 4° with respect to the ecliptic.
It was first identified as at the Leiden Southern Station (Johannesburg-Hartbeespoort) in 1955, extending the body's observation arc by 32 years prior to its official discovery observation.
Physical characteristics.
In the SMASS taxonomy, "Munroe" is characterized as an X-type asteroid. It has an absolute magnitude of 13.5.
Diameter and albedo.
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, "Munroe" measures 3.453 kilometers in diameter and its surface has an exceptionally high albedo of 0.936. On his private blog, Randall Munroe (after whom the asteroid is named) calculates that the asteroid is between 6 and 10 kilometers in diameter, comparable in size to the Chicxulub asteroid.
Lightcurves.
As of 2017, "Munroe"s rotation period, poles and shape remain unknown.
Naming.
In 2013, it was named after Randall Munroe (born 1984), a former NASA roboticist and the author of the webcomic "xkcd". The name was chosen by "xkcd" readers Lewis Hulbert and Jordan Zhu. The official naming citation was published on 22 July 2013 ().


Troubleman Unlimited Records

Troubleman Unlimited Records was a record label specializing in indie rock and similar genres. Founded in 1993, the label was based in Bayonne, New Jersey and owned by Mike Simonetti.
History.
The label started as an offshoot of a fanzine called "Wanna Communicate?", releasing 7" singles. The label grew significantly in the 2000s, releasing full-length albums by many groups who are regularly reviewed in media outlets like "Spin" and Pitchfork. The label focused on noise rock, including releases from Black Dice, Wolf Eyes and Hair Police. Troubleman Unlimited was named "Best Label" by "New York Magazine" in 2005.
In the 21st century, Simonetti started a dance label, Italians Do It Better, with Johnny Jewel of Glass Candy.
Band roster.
The following artists have made at least one release through Troubleman Unlimited or Italians Do It Better.


Vibrating-sample magnetometer

A vibrating-sample magnetometer (VSM) (also referred to as a Foner magnetometer) is a scientific instrument that measures magnetic properties based on Faraday’s Law of Induction. Simon Foner at MIT Lincoln Laboratory invented VSM in 1955 and reported it in 1959. Also it was mentioned by G.W. Van Oosterhout and by P.J Flanders in 1956. A sample is first placed in a constant magnetic field and if the sample is magnetic it will align its magnetization with the external field. The magnetic dipole moment of the sample creates a magnetic field that changes as a function of time as the sample is moved up and down. This is typically done through the use of a piezoelectric material. The alternating magnetic field induces an electric field in the pickup coils of the VSM. The current is proportional to the magnetization of the sample - the greater the induced current, the greater the magnetization. As a result, typically a hysteresis curve will be recorded and from there we can deduce the magnetic properties of the sample being measured.
The idea of vibrating sample came from D. O. Smith's vibrating-coil magnetometer.
Typical VSM overview:.
Conditions for VSM to be effective:.
Importance of pick-up coils:.
These allow the VSM to maximize the induced signal, reduce the noise, give a wide saddle point, minimize the volume in between the sample and electromagnet to achieve a more uniform magnetic field at the sample space. The configuration of the coils can vary depending on the type of material being studied.
Relation to Physics:.
The VSM relies on Faraday's law of induction, with the detection of the emf given by formula_1, where "N" is the number of wire turns, "A" is the area, and formula_2 the angle between the normal of the coil and the B field. However, "N" and "A" are often unnecessary if the VSM is properly calibrated. By varying the strength of the electromagnet through computer software, the external field is sweeped from high to low and back to high. Typically this is automated through a computer process and a cycle of data is printed out. The electromagnet is typically attached to a rotating base so as to allow the measurements be taken as a function of angle. The external field is applied parallel to the sample length and the aforementioned cycle prints out a hysteresis loop. Then using known magnetization of the calibration material and wire volume the high field voltage signal can be converted into emu units - useful for analysis.
Advantages and Disadvantages:.
The precision and accuracy of VSM's are quite high even among other magnetometers and can be on the order of ~ formula_3 emu. VSM's further allow for a sample to be tested at varying angles with respect to it's magnetization letting researches minimize the effects of external influences. However, VSM's are not well suited for determining the magnetization loop due to the demagnetizing effects incurred by the sample. VSM's further suffer from temperature dependence and cannot be used on fragile samples that cannot undergo acceleration (from the vibration).


Type 98 Chi-Ho medium tank

The experimental Type 98 "Chi-Ho" was a prototype Japanese medium tank. It was developed on orders from the Imperial Japanese Army. "Chi Ho" indicates that it is designated as the 5th (I, Ro, Ha, Ni, Ho) medium (Chi) tank. A total of four prototypes were completed. Two were built in 1940 and two were built in 1941. It did not enter production.
History and development.
In the late 1930s, the Imperial Japanese Army was in search for a successor to the Type 89 Medium Tank. The experimental Type 97 Chi-Ni medium tank was considered as meeting the requirement of a "light and low-cost tank which can be deployed in large numbers"; while the Chi-Ha (later the Type 97 Chi-Ha) was thought as the more effective fighting vehicle for the needs of the military. With the outbreak of the Sino-Japanese war on 7 July 1937, the peacetime budgetary limitations were removed and the more capable and expensive Mitsubishi Chi-Ha model was accepted as the new Type 97 medium tank by the army.
However, the army chief staff did not give up on the idea of a lower-cost and lighter weight medium tank and thus this vehicle was developed. A total of four prototypes were built.
Design.
Armament.
Heavy emphasis was placed on a gun with a high penetration and the high velocity 47mm tank cannon was selected. Both the Chi-Ni and the Chi-Ha were equipped with a Type 97 57 mm main gun. The cannon was a short-barreled weapon with a relatively low muzzle velocity, but sufficient as the tank was intended primarily for infantry support.
The shortcomings of the Type 97 Chi-Ha, with its low-velocity 57 mm gun, became clear during the 1939 Battles of Khalkhin Gol against the Soviet Union. The 45 mm gun of the Soviet BT-5 and BT-7 tanks out-ranged the Japanese tank gun, resulting in heavy Japanese losses. This convinced the army of the need for a more powerful gun. The following change order looked closely at the next medium tank shortly before this vehicle was completed. In the change order sent to the tank research committee, Showa 14 were design conditions "for the next tank`s turret, even if taking the 57mm cannon into account, further research will be made into firepower. The caliber, if by no choice, will be no smaller than 47mm. The likelihood of being pressed into tank battles in future wars is something that should be considered." This tank's experimental 47mm tank cannon was derived from the research results of the "Experimental type 97 47mm cannon" and the "experimental 47mm cannon". From June 1940, a completed cannon of the experimental 47mm cannon begun various testing and in September, the experimental 47mm tank cannon was mounted on a Type 98 Chi-Ho turret. The turret was then mounted on a Type 97 Chi-Ha's hull and underwent testing. The Type 1 47 mm tank gun was designed specifically to counter the Soviet tanks.
The intention behind the machine gun being mounted in the forward left side of the turret is not clearly known, but it may be akin to a coaxial machine gun. A coaxial machine gun is placed alongside the main armament on the same axle. With that setup, when using the main cannon, the machine can could help predict where the main cannon's fire would land or suppress the enemy while loading the main armament. The machine gun mounted in the Type 98 turret was not a belt-fed type, but rather the Type 97 tank-mounted heavy machine gun, which used 20-round magazines. This presented a limitation in sustaining continuous firing attacks.
Mobility and testing.
The engine mounted in the tank was a Mitsubishi 120 HP diesel engine. Also, it was the first Japanese made tank to use a hydraulic system in the steering system.
Up until then, some advances over the Chi-Ha variants can be seen, but some aspects in the tank hull were still lagging behind. A sled was attached to the rear part of the hull. This is commonly seen on World War I and inter-war tanks. It was thought that by extending the length of the hull, it gained the benefit of crossing trenches, but in that, there was a problem. As a tank mounts a sled, it becomes tail heavy (center of weight shifts backwards) and that presented uncertainty when crossing wide trenches. By becoming tail heavy, the rear portion of the suspension would undertake a greater load and thus wear out faster. Furthermore, the somewhat increase in weight would reduce mobility. With the applied limitations on the tank's weight, it is not believed that the armor protection level could have been improved. Without a cupola, the ability to observe outside would have been worse than the Chi-Ha.
Mitsubishi and Jidosha Kogyo completed the first two prototypes in 1940 and the Kokura and Sagami Arsenals produced two more by the following year. After field tests, the tank was not selected for production. The Imperial Japanese Army realized that further research was needed and a better design made to counter the 1940s generation of Allied armor, such as the M4 Sherman. A new tank design based on an improved Type 97 design was conceived. The first of this new series was the Type 1 Chi-He medium tank. Work on that design began in 1941. However, production of the Type 1 Chi-He did not begin until 1943, due to the higher priority of steel allocated to the Imperial Navy for warship construction.


Amphetamine Reptile Records

Amphetamine Reptile Records (or AmRep Industries) is a record label which was founded in 1986 by Tom Hazelmyer in Washington state. The label specializes in noise rock and also released "Strap It On", the debut album by alternative metal band Helmet which sold more than 40,000 records. According to Hazelmyer, the success of the album was vital to keeping AmRep going throughout the 1990s, as it "helped support the other things that sold less." The label was the subject of the 2014 documentary "The Color of Noise".
History.
Hazelmyer originally started the label to release records by his band, Halo of Flies. Eventually the label's roster expanded to include releases by Helmet, the Melvins, the Cows, Helios Creed, Chokebore, Servotron and others. Hazelmyer later moved the label to Minneapolis. Today the label is used by the Melvins, H•O•F and other legacy AmRep acts on to release limited edition vinyl. These releases are generally noted for their Linocut artwork, hand carved by Hazelmyer, their limited availability and their highly sought after nature as collector's items.
Much of the AmRep back catalog is now out of print, although many of the releases are available in digital download format and streaming.
On May 13, 2020 Tom Hazelmyer participated in an in-depth interview about the label on Conan Neutron's Protonic Reversal.


689 Zita

689 Zita is a minor planet orbiting the Sun. It was named after Zita of Bourbon-Parma, the last empress of Austria-Hungary.


Greater undecimal neutral second


6077 Messner


Septimal meantone temperament

In music, septimal meantone temperament, also called "standard septimal meantone" or simply "septimal meantone", refers to the tempering of 7-limit musical intervals by a meantone temperament tuning in the range from fifths flattened by the amount of fifths for 12 equal temperament to those as flat as 19 equal temperament, with 31 equal temperament being a more or less optimal tuning for both the 5- and 7-limits. Meantone temperament represents a frequency ratio of approximately 5 by means of four fifths, so that the major third, for instance C-E, is obtained from two tones in succession. Septimal meantone represents the frequency ratio of 56 (7*23) by ten fifths, so that the interval 7:4 is reached by five successive tones. Hence C-A, not C-B, represents a 7:4 interval in septimal meantone.
The meantone tuning with pure 5:4 intervals (quarter-comma meantone) has a fifth of size 696.58 cents . Similarly, the tuning with pure 7:4 intervals has a fifth of size 696.88 cents . 31 equal temperament has a fifth of size 696.77 cents , which does excellently for both of them, having the harmonic seventh only 1.1 cent lower, and the major third 1.2 cent higher than pure (while the fifth is 5.2 cent lower than pure). However, the difference is so small that it is mainly academic.
Theoretical properties.
Septimal meantone tempers out not only the syntonic comma of 81:80, but also the septimal semicomma of 126:125, and the septimal kleisma of 225:224. Because the septimal semicomma is tempered out, a chord with intervals 6:5-6:5-6:5-7:6, spanning the octave, is a part of the septimal meantone tuning system. This chord might be called the "septimal semicomma diminished seventh". Similarly, because the septimal kleisma is tempered out, a chord with intervals of size 5:4-5:4-9:7 spans the octave; this might be called the "septimal kleisma augmented triad", and is likewise a characteristic feature of septimal meantone.
Chords of septimal meantone.
Septimal meantone of course has major and minor triads, and also diminished triads, which come in both an otonal, 5:6:7 form, as for instance C-E-F, and an inverted utonal form, as for instance C-D-F. As previously remarked, it has a septimal diminished seventh chord, which in various inversions can be C-E-G-B, C-E-G-A, C-E-F-A or C-D-F-A. It also has a septimal augmented triad, which in various inversions can be C-E-G, C-E-A or C-F-A. It has both a dominant seventh chord, C-E-G-B, and an otonal tetrad, C-E-G-A; the latter is familiar in common practice harmony under the name German sixth. It likewise has utonal tetrads, C-E-G-B, which in
the arrangement B-E-G-C becomes Wagner's Tristan chord. It has also the subminor triad, C-D-G, which is otonal, and the supermajor triad, C-F-G, which is utonal. These can be extended to subminor tetrads, C-D-G-A and supermajor tetrads C-F-G-B.
11-limit meantone.
Septimal meantone can be extended to the 11-limit, but not uniquely. It is possible to take the interval of 11 by means of 18 fifths up and 7 octaves down, so that an 11:4 is made up of nine tones (e.g. C-E). The 11 is pure using this method if the fifth is of size 697.30 cents, very close to the fifth of 74 equal temperament. On the other hand, 13 meantone fourths up and two octaves down (e.g. C-G) will also work, and the 11 is pure using this method for a fifth of size 696.05 cents, close to the 696 cents of 50 equal temperament. The two methods are conflated for 31 equal temperament, where E and G are enharmonic.


340 Eduarda

Eduarda (minor planet designation: 340 Eduarda) is a main belt asteroid that was discovered by German astronomer Max Wolf on 25 September 1892 in Heidelberg. It was named after German banker and amateur astronomer Heinrich Eduard von Lade.
Photometric observations of this asteroid at the Oakley Observatory in Terre Haute, Indiana, during 2006 gave a light curve with a period of 8.04 ± 0.02 hours and a brightness variation of 0.25 ± 0.03 in magnitude.


Location testing for Gaussian scale mixture distributions

In statistics, the topic of location testing for Gaussian scale mixture distributions arises in some particular types of situations where the more standard Student's t-test is inapplicable. Specifically, these cases allow tests of location to be made where the assumption that sample observations arise from populations having a normal distribution can be replaced by the assumption that they arise from a Gaussian scale mixture distribution. The class of Gaussian scale mixture distributions contains all symmetric stable distributions, Laplace distributions, logistic distributions, and exponential power distributions, etc.
Introduce
the counterpart of Student's t-distribution for Gaussian scale mixtures. This means that if we test the null hypothesis that the center of a Gaussian scale mixture distribution is 0, say, then "t""n""G"("x") ("x" ≥ 0) is the infimum of all monotone nondecreasing functions "u"("x") ≥ 1/2, "x" ≥ 0 such that if the critical values of the test are "u"−1(1 − "α"), then the significance level is at most "α" ≥ 1/2 for all Gaussian scale mixture distributions ["t""G""n"(x) = 1 − "t""G""n"(−"x"),for "x" < 0]. An explicit formula for "t""G""n"("x"), is given in the papers in the references in terms of Student’s t-distributions, "t""k", "k" = 1, 2, …, "n". Introduce
the Gaussian scale mixture counterpart of the standard normal cumulative distribution function, Φ(x).
Theorem. Φ"G"("x") = 1/2 for 0 ≤ "x" < 1, Φ"G"(1) = 3/4, Φ"G"("x") = "C"("x"/(2 − "x"2)1/2) for quantiles between 1/2 and 0.875, where "C"("x") is the standard Cauchy cumulative distribution function. This is the convex part of the curve Φ"G"("x"), "x" ≥ 0 which is followed by a linear section Φ"G"("x") = "x"/(2) + 1/2 for 1.3136… < "x" < 1.4282... Thus the 90% quantile is exactly 4/5. Most importantly,
Note that Φ() = 0.958…, thus the classical 95% confidence interval for the unknown expected value of Gaussian distributions covers the center of symmetry with at least 95% probability for Gaussian scale mixture distributions. On the other hand, the 90% quantile of ΦG("x") is 4/5 = 1.385… > Φ−1(0.9) = 1.282… The following critical values are important in applications: 0.95 = Φ(1.645) = ΦG(1.651), and 0.9 = Φ(1.282) = ΦG(1.386).
For the extension of the Theorem to all symmetric unimodal distributions one can start with a classical result of Aleksandr Khinchin: namely that all symmetric unimodal distributions are scale mixtures of symmetric uniform
distributions.
Open problem.
The counterpart of the Theorem above for the class of all symmetric distributions, or equivalently, for the class of scale mixtures of coin flipping random variables, leads to the following problem:


B tuning

B Tuning or B Standard Tuning is the standard tuning for a seven string guitar, where the strings are tuned B-E-A-D-G-B-E. B tuning can also be achieved on a six-string guitar, when the strings are tuned B-E-A-D-F♯-B, known then as Baritone Tuning. This tuning is popular among several different types of metal bands.
The following is a list of musical groups who use this tuning on six-string or seven-string guitars:


Calipers

A caliper (British spelling also calliper, or in plurale tantum sense a pair of calipers) is a device used to measure the dimensions of an object.
Many types of calipers permit reading out a measurement on a ruled scale, a dial, or a digital display. Some calipers can be as simple as a compass with inward or outward-facing points, but no scale. The tips of the caliper are adjusted to fit across the points to be measured and the dimension read by measuring between the tips with another measuring tool, such as a ruler.
It is used in many fields such as mechanical engineering, metalworking, forestry, woodworking, science and medicine.
Plural vs. singular.
A single tool might be referred to as a "caliper" or as "calipers", like a pair of scissors or glasses (a "plural only" or "plurale tantum" form). In colloquial usage, the phrase "pair of verniers" or just "vernier" might refer to a vernier caliper. Colloquially these phrases can also refer to dial calipers, although they involve no vernier scale.
In machine-shop usage, the term "caliper" is often used in contradistinction to "micrometer", even though outside micrometers are technically a form of the caliper. In this usage, "caliper" implies only the form factor of the vernier or dial caliper (or its digital counterpart).
History.
The earliest caliper has been found in the Greek Giglio wreck near the Italian coast. The ship's find dates to the 6th century BC. The wooden piece already featured a fixed and a movable jaw. Although rare finds, calipers remained in use by the Greeks and Romans.
A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty. The caliper had an inscription stating that it was "made on the "gui-you" day, the first day of the first month of the first year of "Shijianguo" ." The calipers included a "slot and pin" and "graduated in inches and tenths of an inch."
The modern vernier caliper was invented by Pierre Vernier, as an improvement of the nonius of Pedro Nunes.
Types.
Inside caliper.
The inside calipers are used to measure the internal size of an object.
Outside caliper.
Outside calipers are used to measure the external size of an object.
The same observations and technique apply to this type of caliper, as for the above inside caliper. With some understanding of their limitations and usage, these instruments can provide a high degree of accuracy and repeatability. They are especially useful when measuring over very large distances; consider if the calipers are used to measure a large diameter pipe. A vernier caliper does not have the depth capacity to straddle this large diameter while at the same time reach the outermost points of the pipe's diameter. They are made from high carbon steel.
Divider caliper.
In the metalworking field, a divider caliper, popularly called a compass, is used in the process of marking out locations. The points are sharpened so that they act as scribers; one leg can then be placed in the dimple created by a center or prick punch and the other leg pivoted so that it scribes a line on the workpiece's surface, thus forming an arc or circle.
A divider caliper is also used to measure a distance between two points on a map. The two caliper's ends are brought to the two points whose distance is being measured. The caliper's opening is then either measured on a separate ruler and then converted to the actual distance, or it is measured directly on a scale drawn on the map. On a nautical chart the distance is often measured on the latitude scale appearing on the sides of the map: one minute of arc of along any great circle, as for example, any longitude meridian, is approximately one nautical mile or 1852 meters.
Dividers are also used in the medical profession. An ECG (also EKG) caliper transfers distance on an electrocardiogram; in conjunction with the appropriate scale, the heart rate can be determined. A pocket caliper version was invented by cardiologist Robert A. Mackin.
Oddleg caliper.
Oddleg calipers, Hermaphrodite calipers, or Oddleg Jennys, as pictured on the left, are generally used to scribe a line at a set distance from the edge of a workpiece. The bent leg is used to run along the workpiece edge while the scriber makes its mark at a predetermined distance, this ensures a line parallel to the edge.
In the diagram at left, the uppermost caliper has a slight shoulder in the bent leg allowing it to sit on the edge more securely, the lower caliper lacks this feature but has a renewable scriber that can be adjusted for wear, as well as being replaced when excessively worn.
Vernier caliper.
The vernier, dial, and digital calipers give a direct reading of the distance measured with high accuracy and precision. They are functionally identical, with different ways of reading the result. These calipers comprise a calibrated scale with a fixed jaw, and another jaw, with a pointer, that slides along the scale. The distance between the jaws is then read in different ways for the three types.
The simplest method is to read the position of the pointer directly on the scale. When the pointer is between two markings, the user can mentally interpolate to improve the precision of the reading. This would be a simply calibrated caliper, but the addition of a vernier scale allows more accurate interpolation and is the universal practice; this is the vernier caliper.
Vernier, dial, and digital calipers can measure internal dimensions (using the uppermost jaws in the picture at right), external dimensions using the pictured lower jaws, and in many cases depth by the use of a probe that is attached to the movable head and slides along the center of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools.
The vernier scales may include metric measurements on the lower part of the scale and inch measurements on the upper, or vice versa, in countries that use inches. Vernier calipers commonly used in industry provide a precision to 0.01 mm (10 micrometres), or one thousandth of an inch. They are available in sizes that can measure up to 1828 mm (72 in).
Dial caliper.
Instead of using a vernier mechanism, which requires some practice to use, the dial caliper reads the final fraction of a millimeter or inch on a simple dial.
In this instrument, a small, precise rack and pinion drives a pointer on a circular dial, allowing direct reading without the need to read a vernier scale. Typically, the pointer rotates once every inch, tenth of an inch, or 1 millimeter. This measurement must be added to the coarse whole inches or centimeters read from the slide. The dial is usually arranged to be rotatable beneath the pointer, allowing for "differential" measurements (the measuring of the difference in size between two objects, or the setting of the dial using a master object and subsequently being able to read directly the plus-or-minus variance in the size of subsequent objects relative to the master object).
The slide of a dial caliper can usually be locked at a setting using a small lever or screw; this allows simple go/no-go checks of part sizes.
Digital caliper.
A popular refinement replaces the analog dial with an electronic digital display that displays the reading as a numeric value. Rather than a rack and pinion, these calipers use a linear encoder. Some digital calipers can be switched between centimeters or millimeters, and inches. All provide for zeroing the display at any point along with the slide, allowing the same sort of differential measurements as with the dial caliper. Digital calipers may contain a "reading hold" feature, allowing the reading of dimensions after use in awkward locations where the display cannot be seen.
Ordinary 6-in/150-mm digital calipers are made of stainless steel, have a rated accuracy of 0.001 in (0.02mm) and a resolution of 0.0005 in (0.01 mm).
The same technology is used to make longer 8-in and 12-in calipers; the accuracy for longer measurements declines to 0.001 in (0.03 mm) for 100–200 mm and 0.0015 in (0.04 mm) for 200–300 mm.
Increasingly, digital calipers offer a serial data output to allow them to be interfaced with a dedicated recorder or a personal computer. The digital interface significantly decreases the time to make and record a series of measurements, and it also improves the reliability of the records. A suitable device to convert the serial data output to common computer interfaces such as RS-232, Universal Serial Bus, or wireless can be built or purchased. With such a converter, measurements can be directly entered into a spreadsheet, a statistical process control program, or similar software.
The serial digital output varies among manufacturers. Common options are
Like dial calipers, the slide of a digital caliper can usually be locked using a lever or thumb-screw.
Some digital calipers contain a capacitive linear encoder. A pattern of bars is etched directly on the printed circuit board in the slider. Under the scale of the caliper another printed circuit board also contains an etched pattern of lines. The combination of these printed circuit boards forms two variable capacitors. The two capacitances are out of phase. As the slider moves the capacitance changes in a linear fashion and in a repeating pattern. The circuitry built into the slider counts the bars as the slider moves and does a linear interpolation based on the magnitudes of the capacitors to find the precise position of the slider. Other digital calipers contain an inductive linear encoder, which allows robust performance in the presence of contamination such as coolants. Magnetic linear encoders are used in yet other digital calipers.
Micrometer caliper.
A caliper using a calibrated screw for measurement, rather than a slide, is called an "external micrometer caliper gauge", a "micrometer caliper" or, more often, simply a "micrometer". (Sometimes the term "caliper", referring to any other type in this article, is held in contradistinction to "micrometer".)
Comparison.
Each of the above types of calipers has its relative merits and faults.
Vernier calipers are rugged and have long-lasting accuracy, are coolant proof, are not affected by magnetic fields, and are largely shockproof. They may have both centimeter and inch scales. However, vernier calipers require good eyesight or a magnifying glass to read and can be difficult to read from a distance or from awkward angles. It is relatively easy to misread the last digit. In production environments, reading vernier calipers all day long is error-prone and is annoying to the workers. however digital vernier calipers have greater precision than mechanical vernier calipers because the least count of digital vernier calipers is 0.01 mm
Dial calipers are comparatively easy to read, especially when seeking the exact center by rocking and observing the needle movement. They can be set to 0 at any point for comparisons. They are usually fairly susceptible to shock damage. They are also very prone to getting dirt in the gears, which can cause accuracy problems.
Digital calipers switch easily between the centimeter and inch systems. They can be set to 0 easily at any point with a full count in either direction and can take measurements even if the display is completely hidden, either by using a "hold" key, or by zeroing the display and closing the jaws, showing the correct measurement, but negative. They can be mechanically and electronically fragile. Most also require batteries and do not resist coolant well. They are also only moderately shockproof and can be vulnerable to dirt.
Calipers may read to a resolution of 0.01 mm or 0.0005 in, but accuracy may not be better than about ±0.02 mm or 0.001 in for 150 mm (6 in) calipers, and worse for longer ones.
Use.
A caliper must be properly applied against the part in order to take the desired measurement. For example, when measuring the thickness of a plate a vernier caliper must be held at right angles to the piece. Some practice may be needed to measure round or irregular objects correctly.
Accuracy of measurement when using a caliper is highly dependent on the skill of the operator. Regardless of type, a caliper's jaws must be forced into contact with the part being measured. As both part and caliper are always to some extent elastic, the amount of force used affects the indication. A consistent, firm touch is correct. Too much force results in an under indication as part and tool distort; too little force gives insufficient contact and an over indication. This is a greater problem with a caliper incorporating a wheel, which lends mechanical advantage. This is especially the case with digital calipers, calipers out of adjustment, or calipers with a poor quality beam.
Simple calipers are uncalibrated; the measurement taken must be compared against a scale. Whether the scale is part of the caliper or not, all-analog calipers—verniers and dials—require good eyesight in order to achieve the highest precision. Digital calipers have an advantage in this area.
Calibrated calipers may be mishandled, leading to loss of zero. When a calipers' jaws are fully closed, it should, of course, indicate zero. If it does not, it must be recalibrated or repaired. A vernier caliper does not easily lose its calibration but a sharp impact or accidental damage to the measuring surface in the caliper jaw can be significant enough to displace zero. Digital calipers have zero set buttons, for quick recalibration.
Vernier, dial, and digital calipers can be used with accessories that extend their usefulness. Examples are a base that extends its usefulness as a depth gauge and a jaw attachment that allows measuring the center distance between holes. Since the 1970s a clever modification of the moveable jaw on the backside of any caliper allows for step or depth measurements in addition to external caliper measurements, in a similar fashion to a universal micrometer (e.g., Starrett Mul-T-Anvil or Mitutoyo Uni-Mike).
Zero error.
The method to use a vernier scale or caliper with zero error is to use the formula "actual reading = main scale + vernier scale − (zero error)". Zero error may arise due to knocks that affect the calibration at 0.00  mm when the jaws are perfectly closed or just touching each other. Positive zero error refers to the fact that when the jaws of the vernier caliper are just closed, the reading is a positive reading away from the actual reading of 0.00  mm. If the reading is 0.10 mm, the zero error is referred to as +0.10 mm. Negative zero error refers to the fact that when the jaws of the vernier caliper are just closed, the reading is a negative reading away from the actual reading of 0.00  mm. If the reading is −0.08  mm, the zero error is referred to as −0.08  mm.


Thomas Edwin Nevin

Thomas Edwin Nevin (4 October 1906 in Bristol, Somerset – 16 July 1986 in Dublin) was an Irish physicist and academic who had a distinguished career in the field of molecular spectroscopy. He was Professor of Experimental Physics and Dean of the Faculty of Science in University College Dublin (UCD) from 1963 to 1979.
Education and career.
Born in 1906 in Bristol, England, the oldest of seven children of an Irish father and English mother, the family soon settled in Ireland where he spent his youth. From 1919 to 1924 he attended the CBS Sexton Street secondary school in Limerick City. The school had no science program, but Nevin was interested in physics and managed to learn the subject pretty thoroughly on his own. In 1924 he got a scholarship to University College Dublin (UCD). While there he excelled in mathematics and physics, winning first-class honours every year, and earning an honours B.Sc. in Experimental Physics and Mathematics in 1927. He got his M.Sc. under JJ Nolan in 1928 for a treatise on "The Effect of Water Vapour on the Diffusion Coefficients and Mobilities of Ions in the Air". That year he was also awarded an 1851 Research Fellowship (a legacy of The Great Exhibition of 1851), and this enabled him to study spectroscopy at Imperial College, London (1929–1931). In 1931 he returned to UCD to continue his research and was appointed assistant in the department of experimental physics.
In 1940, he was awarded a D.Sc. degree at National University of Ireland (NUI) for previously published work, and in 1942, he was awarded an honorary doctorate at Queen's University Belfast. Throughout the 1930s and 1940s he continued his research in molecular spectroscopy, often working with research groups in fundamental particle and cosmic ray physics. He was a capable administrator at UCD, serving on the university's finance and buildings committees, as well as the academic council and governing body, and he initiated many improvements to the physics department. When J. J. Nolan died in 1952, Nevin succeeded him as Professor of Experimental Physics, a position he held until his retirement in 1979.
Nevin was a strong advocate for expansion of the UCD campus, which for half a century was based at Earlsfort Terrace in the city. As a key member of UCD's academic council and a member of its buildings committee (1957–76), he was instrumental in moving the science faculty to the new Belfield campus in the southern suburbs in 1964.
He was a key figure in the formation of the Irish branch of Institute of Physics in Ireland.
At the Dublin Institute for Advanced Studies (DIAS) he was a member of the governing boards of the school of theoretical physics (1943-1961) and the school of cosmic physics (1948-1956).
On 16 March 1942 he was elected a member of the Royal Irish Academy (RIA) and served on its council from 1944 to 1968.
Personal life.
Thomas E. Nevin was born in Bristol, Somerset on 4 October 1906. He was the eldest of seven children born to Thomas Nevin of Cashel, County Tipperary, and Alice Nevin (née Higginson) of Herefordshire. Áine Ní Chnáimhín (1908–2001) who wrote a biography of Pádraic Ó Conaire was Nevin's sister; historian and trade unionist Donal Nevin was his brother.
In January 1936 he married Monica T. M. Morrissey, a UCD graduate in Celtic studies who went on to serve on the Council of the Royal Society of Antiquaries of Ireland and did research on antiquarian matters for "Irish History Online". The Nevins had four children, all girls.
Thomas E. Nevin Medal.
Each year at UCD, the Thomas E. Nevin Medal and Prize is given to the graduate who obtains First Class Honours and first place in the BSc Honours Degree Examination in Physics.


California Subject Examinations for Teachers

The California Subject Examinations for Teachers, also abbreviated as CSET, is a group of subject matter tests used in California and other states to assess mastery of subject matter content by prospective K-12 teachers. Appropriate subtests of the CSET must be passed before a candidate begins a state-approved teacher preparation program, and satisfies the No Child Left Behind (P.L. 107-110) "highly qualified teacher" requirement.
The tests are administered by National Evaluation Systems, a division of Pearson Education, Inc. Most include both multiple choice and constructed response sections.
The CSET Multiple Subjects Exam is taken by candidates for the multiple subject (elementary education) and Education Specialist (special education) teaching credential. It consists of three subtests. Subtest I covers reading, language, literature, and history; Subtest II covers math and science; Subtest III covers visual and performing arts, physical education, and human development. Subtests may be taken separately or all at once; candidates pay for each subtest separately.
CSET Single Subject Exams are used to assess mastery of specific matter by candidates for the single-subject (secondary) teaching credential. The examination is taken by subject area, such as English or mathematics, and individual tests vary from two to four subtests.