Farad

The farad (symbol: F) is the SI derived unit of electrical capacitance, the ability of a body to store an electrical charge. It is named after the English physicist Michael Faraday. In SI base units 1F = 1s4⋅A2⋅m−2⋅kg−1.
Definition.
One farad is defined as the capacitance across which, when charged with one coulomb, there is a potential difference of one volt. Equally, one farad can be described as the capacitance which stores a one-coulomb charge across a potential difference of one volt.
The relationship between capacitance, charge, and potential difference is linear. For example, if the potential difference across a capacitor is halved, the quantity of charge stored by that capacitor will also be halved.
For most applications, the farad is an impractically large unit of capacitance. Most electrical and electronic applications are covered by the following SI prefixes:
Equalities.
A farad is a derived unit based on four of the seven base units of the International System of Units: kilogram (kg), metre (m), second (s), and ampere (A).
Expressed in combinations of SI units, the farad is:
where , , , , , , , , , , , , Hz = hertz, .
History.
The term "farad" was originally coined by Latimer Clark and Charles Bright in 1861, in honor of Michael Faraday, for a unit of quantity of charge, but by 1873, the farad had become a unit of capacitance. In 1881 at the International Congress of Electricians in Paris, the name farad was officially used for the unit of electrical capacitance.
Explanation.
A capacitor generally consists of two conducting surfaces, frequently referred to as plates, separated by an insulating layer usually referred to as a dielectric. The original capacitor was the Leyden jar developed in the 18th century. It is the accumulation of electric charge on the plates that results in capacitance. Modern capacitors are constructed using a range of manufacturing techniques and materials to provide the extraordinarily wide range of capacitance values used in electronics applications from femtofarads to farads, with maximum-voltage ratings ranging from a few volts to several kilovolts.
Values of capacitors are usually specified in farads (F), microfarads (μF), nanofarads (nF) and picofarads (pF). The millifarad is rarely used in practice (a capacitance of 4.7 mF (0.0047 F), for example, is instead written as ), while the nanofarad is uncommon in North America. The size of commercially available capacitors ranges from around 0.1 pF to (5 kF) supercapacitors. Parasitic capacitance in high-performance integrated circuits can be measured in femtofarads (1 fF = 0.001 pF =  F), while high-performance test equipment can detect changes in capacitance on the order of tens of attofarads (1 aF =  F).
A value of 0.1 pF is about the smallest available in capacitors for general use in electronic design, since smaller ones would be dominated by the parasitic capacitances of other components, wiring or printed circuit boards. Capacitance values of 1 pF or lower can be achieved by twisting two short lengths of insulated wire together.
The capacitance of the Earth's ionosphere with respect to the ground is calculated to be about 1 F.
Informal and deprecated terminology.
The picofarad (pF) is sometimes colloquially pronounced as "puff" or "pic", as in "a ten-puff capacitor". Similarly, "mic" (pronounced "mike") is sometimes used informally to signify microfarads.
Nonstandard abbreviations were and are often used. Farad has been abbreviated "f", "fd", and "Fd". For the prefix "micro-", when the Greek small letter "μ" or the legacy micro sign "μ" is not available (as on typewriters) or inconvenient to enter, it is often substituted with the similar-appearing "u" or "U", with little risk of confusion. It was also substituted with the similar-sounding "M" or "m", which can be confusing because M officially stands for 1,000,000 (or 1,000), and m preferably stands for 1/1000. In texts prior to 1960, and on capacitor packages until more recently, "microfarad(s)" was abbreviated "mf" or "MFD" rather than the modern "μF". A 1940 Radio Shack catalog listed every capacitor's rating in "Mfd.", from 0.000005 Mfd. (5 pF) to 50 Mfd. (50 μF).
"Micromicrofarad" or "micro-microfarad" is an obsolete unit found in some older texts and labels, contains a nonstandard metric double prefix. It is exactly equivalent to a picofarad (pF). It is abbreviated μμF, uuF, or (confusingly) "mmf", "MMF", or "MMFD".
Summary of obsolete capacitance units: (upper/lower case variations are not shown)
Related concepts.
The reciprocal of capacitance is called electrical elastance, the (non-standard, non-SI) unit of which is the daraf.
CGS units.
The abfarad (abbreviated abF) is an obsolete CGS unit of capacitance equal to farads (1 gigafarad, GF).
The statfarad (abbreviated statF) is a rarely used CGS unit equivalent to the capacitance of a capacitor with a charge of 1 statcoulomb across a potential difference of 1 statvolt. It is 1/(10−5"c"2) farad, approximately 1.1126 picofarads.


Edexcel

Edexcel (also known since 2013 as Pearson Edexcel) is a British multinational education and examination body formed in 1996 and wholly owned by Pearson plc since 2005. It is the only privately owned examination board in the United Kingdom. Its name is a portmanteau term combining the words education" and excellence".
Edexcel regulates school examinations under the British Curriculum and offers qualifications for schools on the international and regional scale. It is the UK's largest awarding organisation offering academic and vocational qualifications in schools, colleges and work places in the UK and abroad. It is also recognised internationally. In 2019, Edexcel was the focus of significant controversy following a leak of an A-level examination.
History.
Edexcel was formed in 1996 by the merger of two bodies, the BTEC (Business & Technology Education Council) and ULEAC (University of London Examinations and Assessment Council). In 2003, the Edexcel Foundation (the charity that managed the board) formed a partnership with Pearson plc to set up a new company called London Qualifications Ltd, which was 75% owned by Pearson and 25% by the Edexcel Foundation. London Qualifications Limited changed its name to Edexcel Limited in November 2004 and is now known colloquially as Edexcel and formally as Edexcel Pearson - London Examinations.
In 2005, Edexcel became the only large examination board to be held in private hands, when Pearson plc took complete control. Edexcel subsequently received investment from their new parent company.
Edexcel also offers IAL, known as International Advanced Levels. It is offered only to schools outside the UK. It is considered by the UK NARIC (the National Recognition Information Centre for the United Kingdom) to be of a comparable standard as the GCE Advanced Level. In addition, Edexcel provides the Edexcel International Diploma (ID) which involves the study of 4 A-Levels (3 full A-Levels and 1 AS-Level in either General Studies or Global Development). The British curriculum offered by the Edexcel International board is among the most taught at International Schools along with the curricula offered by Cambridge International Examinations and, the International Baccalaureate Organization.
On 3 April 2013, Pearson rebranded Edexcel and all of its exams 'Pearson Edexcel', in line with a name change that added the prefix 'Pearson' to all of its brands.
Controversies.
As Edexcel is the only privately owned examination board in the UK, questions have been raised on whether the examination board is acting in the best interest of students, or solely as a profit making business, due to the wide range of Edexcel-endorsed text books published by Pearson, the international multi-billion company which owns the board.
2007.
In 2007 it was reported that teachers using Edexcel Music examinations were allowing students to listen to confidential listening paper CDs several days before the examination, by abusing the trust given by the exam board to only check for technical issues. Other exam boards do not allow the practice of checking discs, with AQA specifically instructing teachers not to open the packages containing the CDs before exams.
2014.
In 2014 the loss of an A-Level Core Mathematics C3 Mathematics exam being delivered to an international school in Amsterdam led to a replacement paper being published for the Summer examination series; however, 60 students in the UK took the original paper due to it mistakenly being handed out in two UK and two overseas centres, while the replacement paper was taken by 34,000 students. The replacement paper was criticised for including questions that were not present on the syllabus, and that the students taking the original paper would be unfairly marked.
2015.
Difficulty.
In June 2015, students across the United Kingdom who had taken an Edexcel GCSE Maths paper expressed anger and confusion over questions that "did not make sense" and were "ridiculous", mocking the exam on Twitter. On a Sky News segment, presenter Adam Boulton answered one of the paper's 'hardest' questions with a former maths teacher. As a result, GCSE students across the UK signed a petition made by a candidate requesting that the exam board lowers the grade boundaries as the examination was too hard.
Gender representation.
An additional petition was started by a 17-year-old student requesting to "Ensure the representation of women on the A-Level Music syllabus." The petition asks that music composed by women be added to the Edexcel A-Level Music syllabus which "has a total of 63 different set works from a variety of musical genres and eras." After six days, the petition had over 1,800 signatures and was featured in "The Guardian".
2019.
Question duplication.
In June, Paper 3 of the Mathematics GCSE (Higher Tier, 1MA1/03) appeared to contain an exam question which was published in an AQA (another British exam board) Further Mathematics textbook. The exam question had the same diagram, values and answer as the question in the textbook. Pearson Edexcel said that they were investigating how this might have happened.
Exam difficulty concerns from students.
After students sat the Paper 2 of the new specification Mathematics A-Level (9MA0), many students complained online expressing that the difficulty of the exam was too high and unlike anything seen in past papers. One online petition to lower grade boundaries was signed by thousands of users. Before results day, Pearson Edexcel released a video addressing students about the difficulty concerns and mentioned that independent experts did confirm that the exam was "fair and valid". They acknowledged the first two questions of the exam were more difficult than anticipated, and also claimed that they would make "small adjustments" to "improve the experience" of the exam for future students.
Leak.
Further controversy ensued after the Paper 3 of the new specification Mathematics A-Level (9MA0/3H – sat 14 June), appeared to have been accessed by someone who, late in the night before the exam sitting, posted on Twitter that they would sell a copy of the exam paper for £70. Pearson Edexcel launched an investigation after becoming aware that some scribbled out images of the exam paper were circulated online prior the exam sitting, and found one centre (out of thirty-eight possible suspect centres in one geographic location), who were visited at a very short notice, to have committed a serious and "possibly criminally motivated" security breach of the A-Level maths paper.
Students expressed frustration about the incident; BBC News reported that students believed the incident could have the potential to affect their results. Pearson Edexcel stated that they have "well-established processes to ensure fair and accurate results" and that "grade boundaries will not be affected". On 17 June Edexcel stated that the compromised questions could be removed from the overall assessment, as well as undertaking additional statistical analysis to identify irregular result patterns for particular centres or students.
About 60,000 students were affected in this incident. Two men aged 29 and 32 were arrested on 24 June on suspicion of theft. The men were released under investigation while inquiries continued. Ahead of results day, it was revealed that 78 students who were suspected of being at an advantage from malpractice would have their results withheld. This is the largest number of candidates to be withheld results from a single malpractice incident.
Extremely low A-level mathematics grade boundaries.
After a leak of the A-Level Grade Boundaries ahead of results day, it emerged that in order to pass the new specification Mathematics A-Level (9MA0), candidates needed to score 14% (43 marks out of 300) to pass. OCR (another British exam board) also had similarly low grade boundaries. After these extremely low grade boundaries added flavour to many news headlines, Ofqual said that they were confident the grade boundaries this year were "sound", so shifted their focus onto the previous year's grade boundaries for the new Mathematics A-Level for the 2,000 students who sat it after studying it for one year. Ofqual said "We want to understand why the grade boundaries were so different between the two years.", and had called the significant shifts in boundaries "unusual".
None of the exam boards decided to re-open the 2018 award, after being asked to look at them again by the regulator. This could potentially result in students who sat the new specification Mathematics A-Level (9MA0) in 2018 having their results changed.


Neyman construction

Neyman construction is a frequentist method to construct an interval at a confidence level formula_1 such that if we repeat the experiment many times the interval will contain the true value of some parameter a fraction formula_2 of the time. It is named after Jerzy Neyman.
Theory.
Assume formula_3 are random variables with joint pdf formula_4, which depends on k unknown parameters. For convenience, let formula_5 be the sample space defined by the n random variables and subsequentially define a sample point in the sample space as formula_6
Neyman originally proposed defining two functions formula_7 and formula_8 such that for any sample point,formula_9,
Given an observation, formula_12, the probability that formula_13 lies between formula_14 and formula_15 is defined as formula_16 with probability of formula_17 or formula_18. These calculated probabilities fail to draw meaningful inference about formula_13 since the probability is simply zero or unity. Furthermore, under the frequentist construct the model parameters are unknown constants and not permitted to be random variables.
For example if formula_20, then formula_21. Likewise, if formula_22, then formula_23
As Neyman describes in his 1937 paper, suppose that we consider all points in the sample space, that is, formula_11, which are a system of random variables defined by the joint pdf described above. Since formula_25 and formula_26 are functions of formula_9 they too are random variables and one can examine the meaning of the following probability statement:
That is,formula_41 where formula_42 where formula_31 and formula_32 the upper and lower confidence limits for formula_13
Coverage probability.
The coverage probability, formula_46, for Neyman construction is the frequency of experiments that the confidence interval contains the actual value of interest. Generally, the coverage probability is set to a formula_47 confidence. For Neyman construction, the coverage probability is set to some value formula_46 where formula_49. This value formula_46 tells how confidently that the true value is contained in the interval.
Implementation.
A Neyman construction can be carried out by performing multiple experiments that construct data sets corresponding to a given value of the parameter. The experiments are fitted with conventional methods, and the space of fitted parameter values constitutes the band which the confidence interval can be selected from.
Classic Example.
Suppose formula_9~formula_52, where formula_53 and formula_54 are unknown constants where we wish to estimate formula_53. We can define (2) single value functions, formula_25 and formula_26, defined by the process above such that given a pre-specified confidence level ,formula_46, and random sample formula_59=(formula_60)
Another Example.
formula_68 are iid random variables, and let formula_69. Suppose formula_70. Now to construct a confidence interval with formula_71 level of confidence. We know formula_72 is sufficient for formula_73. So,
This produces a formula_77 confidence interval for formula_73 where,


VAX Unit of Performance

The VAX Unit of Performance, or VUP for short, is an obsolete measurement of computer performance used by Digital Equipment Corporation (DEC). 1 VUP was equivalent to the performance of a VAX 11/780 completing a given task.
Other VAX machines and later workstation designs were compared in performance terms by defining system speed in VUPs, for instance, the VAXft Model 310 ran at 3.8 VUPs, meaning it ran roughly 3.8 times as fast as the 11/780.
The term was used largely within the DEC and its community, and fell from use as more standard ratings like SPEC became more widely used. This was especially true with the introduction of DEC workstations running Unix, in which case the VUP was of little use comparing the platforms to competition systems.


School-based assessment

The Hong Kong Examinations and Assessment Authority (HKEAA) has moved from norm-referenced to standards-referenced assessment, including the incorporation of a substantial school-based summative oral assessment component(SBA) into the compulsory English language subject in the Hong Kong Certificate of Education Examination (HKCEE), a high-stakes examination for all Form 4–5 students (Davison, 2007).
Background.
School-based Assessment (SBA) was first proposed in the Reform Proposals for the Education System in Hong Kong, published in September 2000. According to the proposal, the modes, content and the assessment methods of public examinations should be reviewed (p. 44). A "core-competence" approach, similar to criterion-referencing, will be adopted. In this approach, basic skills and knowledge required by a Form 5 graduate will be indicated and students do not have to compare with the others. Under the education reforms in which a new culture of learning and teaching is to be cultivated, schools can use different modes of broad-based assessments, including observation of students' performance in classroom and participation in project work to promote learning in a more flexible manner. Another benefit is advocating students' all-round development which gives a more comprehensive picture of individual students' learning needs, as well as fosters the positive washback effects of public examinations. It also helps to address the limitations of judging students on their performance in one single examination.
Rationales.
The rationales laid down by the SBA Consultancy Team (2005) for implementing SBA are as follows:
Content.
The SBA component, worth 15% of the total HKCEE English mark, involves four assessments of English oral language skills based on texts—one from each category: print fiction, print non-fiction, non-print fiction, non-print non-fiction—drawn from a programme of independent extensive reading and viewing (SBA Consultancy Team, 2005). At the time the SBA was introduced, students were required to choose at least four texts to read or view over the course of 2 years; keep brief notes in a logbook; and undertake a number of activities in and out of class to develop their independent reading, speaking, and generic skills. Due to teachers' concerns over excessive workload, the requirements have been modified to "at least three texts over the course of 2 years" (Davison, 2007).
The assessment format and requirements as originally specified in the introduction to the SBA in September 2005 are summarised in Table 1.
 Source: (SBA Consultancy Team, 2005, p. 5).
Assessment criteria.
For assessment students are required to partake in interactions with classmates on a particular aspect of the text they have read or viewed, leading up to making a more formal group interaction or an individual presentation on a specific text and responding to questions from their audience (HKEAA, 2008). Students are assessed according to a set of assessment criteria, consisting of a set of descriptors at each of six levels across four domains (HKEAA, 2007). The domains are briefly described as follows:
Future development.
The current SBA for HKCEE English Language will be extended to the Hong Kong Diploma of Secondary Education (HKDSE) English Language Examination from 2012 onwards(HKEAA, 2007). The SBA component will also be extended to other humanities and science subjects in HKDSE (HKEAA, 2009).
Controversies.
Using Brindley’s (1998) framework, the SBA component is controversial in terms of political issues, to do with the purposes and intended use of the assessment; technical issues, primarily to do with validity and reliability; and practical issues, to do with the means by which the assessment was put into practice. These issues were gathered from key stakeholder groups, including teachers, students and education bureau officials.
Politically, in Davison’s (2007) words, “In fact, the SBA guidelines asked teachers to set their own time limits according to the needs of the students, but this was interpreted through the prism of teachers’ existing experience—many schools used buzzers and stopwatches to allocate an identical period of time to each students, with the result that in some schools students’ stress levels were high and their “performance” very contrived and/or rushed. As an outcome-oriented standards-referenced system, SBA is a significant cultural and attitudinal change, not only for teachers but for the whole school community, including students and parents. Hence, it is not surprising that fairness was a deep-seated sociocultural, not just political concern."
Technically, many teachers and students are concerned over validity, reliability and fairness of the SBA component. While teacher-educators and researchers view that SBA will enhance the validity and reliability of the HKCEE theoretically, some frontline teachers and students are sceptical on this.
As for practical issues, teachers raised such concerns as:


Susan J. Devlin

Susan J. Devlin is an American statistician who has contributed to highly-cited research on robust statistics and local regression.
Education and career.
Devlin earned a bachelor's degree in mathematics from William Smith College in 1968, and has a master's degree in statistics from Rutgers University.
After completing her bachelor's degree, she began working for Bell Labs, and completed her master's degree on a part-time basis while working there. After the 1984 breakup of the Bell system, she moved to Bellcore, and in 1987 her responsibilities at Bellcore shifted from research in statistics to its application in modeling client satisfaction with Bellcore's services. In 1997, she retired from Bellcore and became a founding principal of The Artemis Group, a New Jersey-based marketing consulting firm.
After moving to Thomaston, Maine she became president of the Thomaston Historical Society.
Service.
Devlin chaired the Committee on Women in Statistics (CoWiS) of the American Statistical Association for 1984–1985. She was chair of the Statistical Consulting Section of the American Statistical Association for 2005.
Recognition.
Devlin became a Fellow of the American Statistical Association in 2005.


Bang on a Can

Bang on a Can is a multi-faceted contemporary classical music organization based in New York City. It was founded in 1987 by three American composers who remain its artistic directors: Julia Wolfe, David Lang, and Michael Gordon. Called "the country's most important vehicle for contemporary music" by the "San Francisco Chronicle", the organization focuses on the presentation of new concert music, and has presented hundreds of musical events worldwide.
Notable performances.
Bang on a Can is perhaps best known for its Marathon Concerts, during which an eclectic mix of pieces are performed in succession over the course of many hours while audience members, who are encouraged to maintain a "jeans-and-tee-shirt informality," are welcome to come and go as they please. For the twentieth anniversary of their Marathon Concerts, Bang on a Can presented twenty-six hours of uninterrupted music at the World Financial Center Winter Garden Atrium in New York City.
Among Bang on a Can's early events were performances by John Cage, premieres of Glenn Branca’s epic symphonies for massed electric guitars, and fully staged operas by Harry Partch, featuring the composer's original instruments.
Programs.
Bang on a Can Summer Festival at MASS MoCA.
In 2002, Bang on a Can began the yearly Summer Institute of Music, a program at the Massachusetts Museum of Contemporary Art (MASS MoCA) for young composers and performers. This program is sometimes referred to by the nickname "Banglewood" in reference to the nearby but far more traditional Tanglewood Music Festival.
Staged Works.
The three artistic directors occasionally collaborate by jointly composing large staged works, often without revealing which sections each contributed. Examples include:
People's Commissioning Fund (PCF).
Bang on a Can has commissioned and premiered pieces by composers including Steve Reich, Terry Riley, Michael Nyman, John Adams, Somei Satoh, Iva Bittová, Roberto Carnevale, Ornette Coleman, Donnacha Dennehy and Bun-Ching Lam. In 1998 the organization began the People's Commissioning Fund, which supports the creation of new musical compositions by pooling contributions from numerous member-commissioners whose donations range from $5 to $5,000.
Bang on a Can All-Stars.
The Bang on a Can All-Stars is an amplified sextet formed by its parent organization in 1992. The All-Stars tour internationally and have received awards and public recognition for their work in the contemporary classical music field.
The instrumentation of the Bang on a Can All-Stars is clarinet, cello, electric guitar, piano/keyboard, percussion, double bass. Current members include Ashley Bathgate, Robert Black, Vicky Chow, David Cossin, Arlen Husklo, Mark Stewart and Ken Thomson.
Asphalt Orchestra.
Asphalt Orchestra is Bang on a Can's 12-piece marching band. The ensemble's premiere performance was in 2009 at the Lincoln Center Out of Doors festival, and featured new commissioned works by Tyondai Braxton (of experimental rock group Battles), Goran Bregovic, and Stew and Heidi Rodewald, alongside arrangements of songs by Björk, Meshuggah, Mingus, Nancarrow, and Zappa.
"The New York Times" has called Asphalt Orchestra's members "12 top-notch brass and percussion players", and praised their performance as "coolly brilliant and infectious."
Found Sound Nation.
An independent project founded in 2009 and produced by Bang on a Can, Found Sound Nation (FSN) engages at-risk youth and underrepresented communities producing original audio and video projects across the globe in economically disparate settings. The work of FSN emphasizes a mobile, accessible, collaborative way of recording and producing professional quality music, a technique developed by combining the art music traditions of Bang on a Can with traditions of musique concrète, hip hop, and contemporary composition.
FSN has led site-specific projects in New York City, India, Zimbabwe, Mexico, Italy, Switzerland and Haiti.
In 2012, the project received an award from the U.S. Department of State to produce OneBeat, an international music exchange which will bring together innovative musicians from around the world to compose, produce and perform original music.
Found Sound Nation was co-founded by Christopher Marianetti and Jeremy Thal. The project is directed by Marianetti, Thal and Elena Moon Park.
Recordings.
In the past, Bang on a Can released recordings on Composers Recordings Inc. (CRI), Sony Classical, Point Music (Universal), and Nonesuch, but now the majority of its recordings are found on its own record label, Cantaloupe Music. In addition to releasing works by Gordon, Wolfe, and Lang, the label releases CDs of music by composers and musical groups affiliated with the organization, including Evan Ziporyn, Phil Kline, Alarm Will Sound, Icebreaker, Ethel, Gutbucket, R. Luke DuBois, and Don Byron among many, many others.
Below is a partial discography of released works performed by Bang on a Can:


9996 ANS


White light scanner

A white light scanner (WLS) is a device for performing surface height measurements of an object using coherence scanning interferometry (CSI) with spectrally-broadband, "white light" illumination. Different configurations of scanning interferometer may be used to measure macroscopic objects with surface profiles measuring in the centimeter range, to microscopic objects with surface profiles measuring in the micrometer range. For large-scale non-interferometric measurement systems, see structured-light 3D scanner.
Description.
Vertical scanning interferometry is an example of low-coherence interferometry, which exploits the low coherence of white light. Interference will only be achieved when the path length delays of the interferometer are matched within the coherence time of the light source. VSI monitors the fringe contrast rather than the shape of the fringes.
Fig. 2 illustrates a Twyman–Green interferometer set up for white light scanning of a macroscopic object. Light from the test specimen is mixed with light reflected from the reference mirror to form an interference pattern. Fringes appear in the CCD image only where the optical path lengths differ by less than half the coherence length of the light source, which is generally on the order of micrometers. The interference signal (correlogram) is recorded and analyzed as either the specimen or reference mirror is scanned. The focus position of any particular point on the surface of the specimen corresponds to the point of maximum fringe contrast (i.e. where the modulation of the correlogram is greatest).
Fig. 3 illustrates a white light interferometric microscope using a Mirau interferometer in the objective. Other forms of interferometer used with white light include the Michelson interferometer (for low magnification objectives, where the reference mirror in a Mirau objective would interrupt too much of the aperture) and the Linnik interferometer (for high magnification objectives with limited working distance). The objective (or alternatively, the sample) is moved vertically over the full height range of the sample, and the position of maximum fringe contrast is found for each pixel.
The chief benefit of low-coherence interferometry is that systems can be designed that do not suffer from the 2 pi ambiguity of coherent interferometry, and as seen in Fig. 1, which scans a 180 μm × 140 μm × 10 μm volume, it is well suited to profiling steps and rough surfaces. The axial resolution of the system is determined by the coherence length of the light source and is typically in the micrometer range. Industrial applications include in-process surface metrology, roughness measurement, 3D surface metrology in hard-to-reach spaces and in hostile environments, profilometry of surfaces with high aspect ratio features (grooves, channels, holes), and film thickness measurement (semi-conductor and optical industries, etc.).
Technical.
White-light interferometry scanning (WLS) systems capture intensity data at a series of positions along the vertical axis, determining where the surface is located by using the shape of the white-light interferogram, the localized phase of the interferogram, or a combination of both shape and phase. The white light interferogram actually consists of the superposition of fringes generated by multiple wavelengths, obtaining peak fringe contrast as a function of scan position, that is, the red portion of the object beam interferes with the red portion of the reference beam, the blue interferes with the blue, and so forth.
In a WLS system, an imaging interferometer is vertically scanned to vary the optical path difference. During this process, a series of interference patterns are formed at each pixel in the instrument field of view. This results in an interference function, with interference varying as a function of optical path difference. The data are stored digitally and processed in a variety of ways depending on the system manufacturer, including being Fourier-transformed into frequency space, subject to cross-correlation methods, or analysis in the spatial domain.
If a Fourier transform is used, the original intensity data are expressed in terms of interference phase as a function of wavenumber. Wavenumber k is a representation of wavelength in the spatial frequency domain, defined by k = 2π/λ. If phase is plotted versus wavenumber, the slope of the function corresponds to the relative change in group-velocity optical path difference DG by Dh = DG/2nG where nG is group-velocity index of refraction. If this calculation is performed for each pixel, a three-dimensional surface height map emerges from the data.
In the actual measuring process, the optical path difference is steadily increased by scanning the objective vertically using a precision mechanical stage or piezoelectric positioner. Interference data are captured at each step in the scan. In effect, an interferogram is captured as a function of vertical position for each pixel in the detector array. To sift through the large amount of data acquired over long scans, many different techniques can be employed. Most methods allow the instrument to reject raw data that do not exhibit sufficient signal-to-noise. The intensity data as a function of the optical path difference are processed and converted to height information of the sample.


709 Fringilla

709 Fringilla is a minor planet orbiting the Sun.


Orders of magnitude (force)

The following list shows different orders of magnitude of force.
Since weight under gravity is a force, several of these examples refer to the weight of various objects. Unless otherwise stated, these are weights under average Earth gravity at sea level.


Policy Aptitude Test

The Policy Aptitude Test (PAT) is an offline written test held in India. This test scores a person on the bases of "General Knowledge", "Numerical Problem Solving", "Policy Aptitude", "Logical Reasoning", "English Language" and "Policy Analysis Ability". The National Law School of India University, Bengaluru (NLSIU) started this exam and use the test for selecting students for its Public Policy Programme. The test is conducted every year.
Exam format.
Policy Aptitude Test (PAT) have two parts. First part is multiple choice section with negative marking. Second part is descriptive analytical writing about a policy issue. Only those who obtain minimum of 40% of marks in the first part will be evaluated for the second part.
First part of Policy Aptitude Test have five components: General Knowledge, Numerical Problem Solving, Policy Aptitude, Logical Reasoning and English Language. Each component have 20 questions. Each question carries 1 mark, and negative marking is -0.25. All components have equal weight.
Second part of Policy Aptitude Test is for 50 marks and it concerns descriptive writing about an issue that is provided. The second part examine candidate's policy analysis ability as well as English comprehension. Both parts together, Policy Aptitude Test carries 150 marks. Total duration of Policy Aptitude Test is of two hours.


Romanian Baccalaureate

The Bacalaureat (or "bac" for short) is an exam held in Romania and Moldova when one graduates high school ().
Romania.
History.
The Romanian Baccalaureate evolved over time.
Present.
Unlike the French Baccalaureate, the Romanian one has a single degree. The subjects (except subject A) depend on the profile studied (): mathematics and computer science (), philology (), natural sciences (), social sciences (), or various other vocational tracks (), and the candidate's choice.
The exam covers the whole high school curriculum and the marking scale is between 1 and 10. In order to pass, students must obtain at least 5.00 in every subject with a minimum of 6.00 overall.
Although a student obtained 5.00 every year in high school at a subject, they can obtain 1.00 as well as 10.00 at the National Baccalaureate Exam at that same subject. The grades obtained in high school do not affect or interact in any way with the grade written on the Romanian "Diploma de Bacalaureat".
In order to overcome a national problem of discrimination, the final grade written on the Romanian "Diploma de Bacalaureat" is equally obtained by every student, regardless of the difference of study intensity between schools and profiles. All the graduates in the country take the exam at the same time, having to solve the same subjects. The subjects vary from profile to profile.
For example, in high school, a computer-science student will obtain harder a high grade at Mathematics than a natural sciences student, as the difficulty varies.
In addition to this, all the high schools are ranked by the Ministry of Education, so a low grade obtained in the top schools does not mean that one student is less qualified than another who obtained a higher grade in a lower ranked school.
Moldova.
Moldavian Bacalaureat consists of four exams. Pupils from schools with a language of instruction other than Romanian must take one supplementary exam in their native language and literature.
Exams usually take place in June. All of them are written and each is graded separately.
Students must also choose one more subject taught in school. The majority take Geography or Chemistry.
Subjects.
The baccalaureate has up to 5 modules, each one graded separately. Module E, the written examination, is the one considered for admission to higher education.
Competence exams.
A, B and D are marked with: Beginner, Average, Advanced and Experienced.
Written exams.
Each exam takes three hours.


Lancashire Evening Post

The Lancashire Evening Post is a daily newspaper based in Fulwood, a suburb of the city of Preston, Lancashire, England. According to the British Library, its first edition was published on 18 October 1886. It is known locally as the "LEP".


Nipperkin

The nipperkin is a unit of measurement of volume, equal to one-half of a quarter-gill, one-eighth of a gill, or one thirty-second of an English pint. In other estimations, one nip (an abbreviation that originated in 1796) is either one-third of a pint, or any amount less than or equal to half a pint. A nipperkin is also one-eighth of a pint of beer or any other liquor.


D-flat minor

D-flat minor is a theoretical key based on D, consisting of the pitches D, E, F, G, A, B, and C. Its key signature has six flats and one double flat. Its relative major is F-flat major (usually replaced by E major), and its parallel major is D-flat major. Its direct enharmonic equivalent, C-sharp minor, is normally used.
The D-flat natural minor scale is:
\override Score.TimeSignature #'stencil = ##f
\relative c' {
 \clef treble \key des \minor \time 7/4 des4^\markup { Natural minor scale } es fes ges aes beses ces des ces beses aes ges fes es des2
 \clef bass \key des \minor
</score>
Changes needed for the melodic and harmonic versions of the scale are written in with accidentals as necessary. The D-flat harmonic minor and melodic minor scales are:
\override Score.TimeSignature #'stencil = ##f
\relative c' {
 \clef treble \key des \minor \time 7/4 des4^\markup { Harmonic minor scale } es fes ges aes beses c des c beses aes ges fes es des2
</score>
\override Score.TimeSignature #'stencil = ##f
\relative c' {
 \clef treble \key des \minor \time 7/4 des4^\markup { Melodic minor scale (ascending and descending) } es fes ges aes bes c des ces! beses! aes ges fes es des2
</score>
D-flat minor is usually notated as the enharmonic key of C-sharp minor, as in the second and third measures of Amy Beach's "Canticle of the Sun". However, unusually, two of Verdi's most well-known operas, "La traviata" and "Rigoletto", both end in D-flat minor (although written with the five-flat key signature of the parallel major). Mahler's thematic motif "der kleine Appell" ("call to order") from his Fourth and Fifth Symphonies uses both notations: in his Symphony No. 4 (first movement) it is in D-flat minor, but in his Symphony No. 5 it is in C-sharp minor. In the Adagio of his Symphony No. 9 a solo bassoon interpolation following the main theme appears first in D-flat minor, returning twice more notated in C-sharp minor. Likewise, in the Adagio of Bruckner's Symphony No. 8, phrases that are tonally in D-flat minor are notated as C-sharp minor.


Ancient mode


TestDaF

The TestDaF, formally Test Deutsch als Fremdsprache ("Test of German as a foreign language"), is a standardised language test of German proficiency for non-native German speakers. It aims at people who would like to study at, or academics and scientists who want to work in, German universities. The test is run by the TestDaF-Institut.
The test can be taken in 95 different countries around the world. The test covers listening comprehension, reading comprehension, writing and speaking, and is recognised by German universities as proof of prospective students' ability.
The grades of candidates are marked in terms of three levels, TDN 3 — 5, which correspond to the Common European Framework of Reference for Languages levels B2–C1.
The certificate is valid for an unlimited period of time.
History.
A standardised language examination for foreign students enrolling in German universities was first proposed in 1996 during the Conference of the Cultural Minister ("Kultusministerkonferenz").
In early 1998, the financial support from Foreign Office (Auswärtigen Amt) and the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung) became available and German Academic Exchange Service (DAAD) was commissioned to hold a bidding for the project to develop a central language examination. In the same year, the contract was awarded to a consortium composed of the University of Hagen, the Department of Linguistic Research of Ruhr-University Bochum, Goethe-Institut and the Carl Duisberg Centre in Cologne.
The project began on 1 August 1998. Before 31 July 2000 three modal tests had been drafted and were tested worldwide. The performance description, marking criteria and evaluation procedures were worked out and an item bank for prototype, a database of participants and a test database were all set up.
On 26 April 2001, the TestDaF was taken for the first time.
Supporting organisations.
The tasks of the TestDaF have been developed by the TestDaF-Institut, which is an institution run by the Society for Academic Study Preparation and Test Development ("Gesellschaft für Akademische Studienvorbereitung und Testentwicklung e.V."). It is also supported by, among others, the German Rectors’ Conference ("Hochschulrektorenkonferenz"), German Academic Exchange Service and the Goethe-Institut.
Target group.
The primary target group of the TestDaf examination is the student applicants who have obtained their qualification in foreign countries but want to continue their study in Germany. In accordance to the Law of Higher Education ("Landeshochschulgesetz"), they need a proof of their proficiency in German in order to fulfil the language requirement, and thus TestDaF would be a useful.
There are also other target groups who would be interested to take the exam:
As TestDaf does not offer examinations in different levels, the question paper for all candidates are the same. Therefore, TestDaF is only suitable for advanced learners but not beginners.
Examination.
All the topics and tasks in the test are set within the general context of higher education. They are intended for candidates of all disciplines and academic backgrounds.
The examination consists of 4 parts:
The examination as a whole lasts for 3 hours 10 minutes, not including the breaks. The first three parts of the exam are tested in a classroom context, while the oral examination is done by speaking to a computer.
Grading.
The result of TestDaf is not marked as simply "pass" or "fail". Since the question papers are the same for candidates, and the test needs to separate the examinees into different levels, the results of the examinees are given in three different levels:
If the candidate does not reach the lowest level, "unter TDN 3" (lower than TDN 3) is printed on the certificate.
The test consists of four parts. Each part is separately graded and the sub-grades are also shown on the certificate. Some universities demand their applicants to get a certain grade in all parts of the exam (the grade is depended on the applied programme and subject), but some count the marks just in total. When a candidate fails to reach the required grade, they can re-take the exam.
The exam is marked centrally by well-trained markers.
The three TestDaF levels are designed in accordance with the Common European Framework of Reference for Languages (CEFR) as well as the performance descriptions set by the Association of Language Testers in Europe (ALTE). TDN 3 and the lower half of TDN 4 correspond to the B2 level in CEFR, and the upper half of TDN 4 and TDN 5 correspond to the C1 level.
Certificate.
Within six weeks the candidates receive a certificate issued by the Test Centre. The certificate shows the grades of all parts of the examination and the detailed description of the reached level can be read at the back side of the certificate. If the candidate has not reached the lowest level, i.e. TDN 3, then "unter TDN 3" (lower than TDN 3) would be shown on the certificate. The certificate is valid for an unlimited period of time.
University enrollment.
In general students must get TDN 4 in all parts of the examinations in order to be admitted into universities in Germany. But since every university in Germany has its own admissions policy, it is at the discretion of individual universities to admit applicants whose scores are below TDN 4 to their courses of study, depending on factors such as the course subject, type of degree awarded and course duration.
If the candidate gets a score of TDN 5, it shows that they have a very good knowledge of German, above that required at the beginning of their studies.
Test centres.
There are approximately 450 test centres in 95 countries worldwide, offering the TestDaf exams six times a year. the officially approved test centres, which are managed by TestDaF-Institut, are usually located at German and foreign universities and other higher education institutes, DAAD editorial offices, Goethe-Institut, as well as the Adult high schools ("Volkshochschule") and language schools in Germany. The test centres are responsible for:
Preparation for TestDaF.
There are many preparation courses for TestDaF in Germany as well as foreign countries. These courses are offered by official test centres as well as other language schools. Relevant information can be obtained at the official website of TestDaf.
At the website of TestDaF, tips for the examination are available and sample papers can also be downloaded.
Sometimes, new tests of TestDaF need to be tested, and if possible, there are chances that one can register to do the new test under test in order to be familiar with the test format.
Before registering for the exam, it is also possible to do a placement test at the website of TestDaF, so as to check the level of one's language and decide if it is suitable to register for the examination at that time.
The TestDaF-Institut, however, does not release the test to the public, making it very hard to study alone, and most of the time, acquire a preparation course which could get expensive, considering the already high price of the test.
Advantages and disadvantages of TestDaF.
TestDaF-Institut claims that there are many advantages for the candidate to decide to sit for the TestDaF:
However, there is also disadvantage of taking the TestDaF, especially when compared with the Deutsche Sprachprüfung für den Hochschulzugang (DSH), where one could also fulfil the language requirement for entering German universities by getting a pass.
Examination fee.
The fee of the examination varies according to the level of development of the country.
Statistics.
The number of TestDaF candidates has increased from 7,498 candidates in 2003 took to 24,261 in 2012. In 2003 there were only 211 test centres but this number had increased to 440 by 2012.


X-ray interferometer

An X-ray interferometer is analogous to a neutron interferometer. It has been suggested that it may offer the very highest spatial resolution in astronomy, though the technology is unproven as of 2008.
One technique is triple Laue interferometry (LLL interferometry).


Latvian units of measurement

A number of units of measurements were used in Latvia to measure length, mass, area, and so on. Russian and local measures were used since 1845, and the former system before those, was that of the Netherlands.
System before metric system.
A number of units were used in Russian and local systems.
Length.
Units included:
1 elle = 0.537 m
1 quartier = elle
1 meile = 7 verste (Russian) = 7.468 km.
Mass.
One pfund was equal to 0.419 kg.
Area.
One kapp was equal to 148.64 2. Some other units included:
1 pourvete = 25 kapp
1 loofstelle = 25 kapp
1 tonnstelle = 35 kapp.
Volume.
One faden was equal to 4.077 m3.
Capacity.
One stoof was equal to 1.2752 l. Some other units included:
1 kanne = 2 stoof
1 kulmet = 9 stoof
1 anker = 30 stoof
1 poure = 54 stoof
1 loof = 54 stoof
1 tonne = 108 stoof.


Giovanni Francesco Zarbula

Giovanni Francesco Zarbula was a mural painter and sundial designer from Piedmont Italy who created a hundred or more vertical and vertical declining sundials in the French and Italian Alpes between 1830 and 1881. He worked exclusively in Savoy, in Piémont, the Valley of the Ubaye, le Queyras and around Briançon.
Laying out the dial.
Zarbula's method was one of observation then geometric construction. He did not need to know the latitude or declination of the wall, he did not use tables or calculations he just worked directly on the wall. All his dial were within 2° of the 45th parallel, simplifying the construction, and all gave five-minute accuracy.
All the rest of the dial was laid out using a 45° square, with a 15° measure at the end.
The colours.
Zarbula treated his paintings as frescos so the body colour was embedded in the supporting lime mortar. He didn't use organic pigments, just oxides. These do not fade in the strong alpine sunlight.
Existing Dials (cadrans).
Of the hundred dials by Zarbula, about 50 have survived, and a further dozen show visible traces.
In Hautes-Alpes, seven dials are protected as "monument historique".
His dials can be divided into three specific styles Öiseau (Birds), Geometric, Baroque. The birds that appear in the dials of the early 1840s include toucans, jabirus, parakeets and other exotic birds not seen in these mountains. The geometric works of the late 1840s and 1850s are noted or their simplicity, and contain a little "trompe-l'œil" to give the design some artificial depth. The baroque dials are contain birds, vases, full "trompe-l'œil" and false-marbling. They contain the symbols of the Second Empire (1852-1870) and Napoleon III particularly the Imperial Eagle. The dials produced after 1865 include the Masonic device of the Square and Compasses: this is co-incidental to the rise and acceptance of masonry on both sides of the Italian French border.


Accretionary wedge

An accretionary wedge or accretionary prism forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.
An accretionary complex is a current (in modern use) or former accretionary wedge. Accretionary complexes are typically made up of a mix of turbidites of terrestrial material, basalts from the ocean floor, and pelagic and hemipelagic sediments. For example, most of the geological basement of Japan is made up of accretionary complexes.
Materials within an accretionary wedge.
Accretionary wedges and accreted terranes are not equivalent to tectonic plates, but rather are associated with tectonic plates and accrete as a result of tectonic collision. Materials incorporated in accretionary wedges include:
Elevated regions within the ocean basins such as linear island chains, ocean ridges, and small crustal fragments (such as Madagascar or Japan), known as terranes, are transported toward the subduction zone and accreted to the continental margin. Since the Late Devonian and Early Carboniferous periods, some 360 million years ago, subduction beneath the western margin of North America has resulted in several collisions with terranes, each producing a mountain-building event. The piecemeal addition of these accreted terranes has added an average of in width along the western margin of the North American continent.
Geometry.
The topographic expression of the accretionary wedge forms a lip, which may dam basins of accumulated materials that, otherwise, would be transported into the trench from the overriding plate. Accretionary wedges are the home of mélange, intensely deformed packages of rocks that lack coherent internal layering and coherent internal order.
The internal structure of an accretionary wedge is similar to that found in a thin-skinned foreland thrust belt. A series of thrusts verging towards the trench are formed with the youngest most outboard structures progressively uplifting the older more inboard thrusts.
The shape of the wedge is determined by how readily the wedge will fail along its basal decollement and in its interior; this is highly sensitive to pore fluid pressure. This failure will result in a mature wedge that has an equilibrium triangular cross-sectional shape of a critical taper. Once the wedge reaches a critical taper, it will maintain that geometry and grow only into a larger similar triangle.
Impacts of accretionary wedges.
The small sections of oceanic crust that are thrust over the overriding plate are said to be obducted. Where this occurs, rare slices of ocean crust, known as ophiolites, are preserved on land. They provide a valuable natural laboratory for studying the composition and character of the oceanic crust and the mechanisms of their emplacement and preservation on land. A classic example is the Coast Range ophiolite of California, which is one of the most extensive ophiolite terranes in North America. This oceanic crust likely formed during the middle Jurassic Period, roughly 170 million years ago, in an extensional regime within either a back-arc or a forearc basin. It was later accreted to the continental margin of Laurasia.
Longitudinal sedimentary tapering of pre-orogenic sediments correlates strongly with curvature of the submarine frontal accretionary belt in the South China Sea margin, suggesting that pre-orogenic sediment thickness is the major control on the geometry of frontal structures. The preexisting South China Sea slope that lies obliquely in front of the advancing accretionary wedge has impeded the advancing of frontal folds resulting in a successive termination of folds against and along strike of the South China Sea slope. The existence of the South China Sea slope also leads the strike of impinging folds with NNW-trend to turn more sharply to a NE-strike, parallel to strike of the South China Sea slope. Analysis shows that the pre-orogenic mechanical/crustal heterogeneities and seafloor morphology exert strong controls on the thrust-belt development in the incipient Taiwan arc-continent collision zone.
In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.
Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Results from some studies show that pore pressure in accretionary wedges can be viewed as a dynamically maintained response to factors which drive pore pressure (source terms) and those that limit flow (permeability and drainage path length). Sediment permeability and incoming sediment thickness are the most important factors, whereas fault permeability and the partitioning of sediment have a small effect. In one such study, it was found that as sediment permeability is increased, pore pressure decreases from near-lithostatic to hydrostatic values and allows stable taper angles to increase from ∼2.5° to 8°–12.5°. With increased sediment thickness (from ), increased pore pressure drives a decrease in stable taper angle from 8.4°–12.5° to <2.5–5°. In general, low-permeability and thick incoming sediment sustain high pore pressures consistent with shallowly tapered geometry, whereas high-permeability and thin incoming sediment should result in steep geometry. Active margins characterized by a significant proportion of fine-grained sediment within the incoming section, such as northern Antilles and eastern Nankai, exhibit thin taper angles, whereas those characterized by a higher proportion of sandy turbidites, such as Cascadia, Chile, and Mexico, have steep taper angles. Observations from active margins also indicate a strong trend of decreasing taper angle (from >15° to <4°) with increased sediment thickness (from <1 to 7 km).
Rapid tectonic loading of wet sediment in accretionary wedges is likely to cause the fluid pressure to rise until it is sufficient to cause dilatant fracturing. Dewatering of sediment that has been underthrust and accreted beneath the wedge can produce a large steady supply of such highly overpressured fluid. Dilatant fracturing will create escape routes, so the fluid pressure is likely to be buffered at the value required for the transition between shear and oblique tensile (dilatant) fracture, which is slightly in excess of the load pressure if the maximum compression is nearly horizontal. This in turn buffers the strength of the wedge at the cohesive strength, which is not pressure‐dependent, and will not vary greatly throughout the wedge. Near the wedge front the strength is likely to be that of the cohesion on existing thrust faults in the wedge. The shear resistance on the base of the wedge will also be fairly constant and related to the cohesive strength of the weak sediment layer that acts as the basal detachment. These assumptions allow the application of a simple plastic continuum model, which successfully predicts the observed gently convex taper of accretionary wedges.
Pelayo and Weins have postulated that some tsunami events have resulted from rupture through the sedimentary rock along the basal decollement of an accretionary wedge.
Backthrusting of the rear of the accretionary wedge, arcward over the rocks of the forearc basin, is a common aspect of accretionary tectonics. An older assumption that backstops of accretionary wedges dip back toward the arc, and that accreted material is emplaced below such backstops, is contradicted by observations from many active forearcs that indicate (1) backthrusting is common, (2) forearc basins are nearly ubiquitous associates of accretionary wedges, and (3) forearc basement, where imaged, appears to diverge from the sedimentary package, dipping under the wedge while the overlying sediments are often lifted up against it. Backthrusting may be favored where relief is high between the crest of the wedge and the surface of the forearc basin because the relief must be supported by shear stress along the backthrust.


Ethel Gilbert

Ethel S. Gilbert is an American biostatistician and an expert in the risks of radiation-induced cancer, including cancers in nuclear workers and second cancers in radiation therapy patients.
Education and career.
Gilbert is a graduate of Oberlin College, and completed a Ph.D. in biostatistics at the University of Michigan.
She has worked at the Pacific Northwest National Laboratory, the Radiation Effects Research Foundation, and at the National Cancer Institute from 1996 until her 2016 retirement.
She also held a faculty position in biostatistics and biomathematics at the University of Washington.
Recognition.
Gilbert won the George W. Snedecor Award of the Committee of Presidents of Statistical Societies in 1981 for her work on "the assessment of risks from occupational exposure to ionizing radiation".
She became a Fellow of the American Statistical Association in 1988.
She won the NIH MERIT award in 2003, and the National Cancer Institute gave her their Director's Award in 2015. In 2016, the Royal Swedish Academy of Sciences gave Gilbert their Gold Medal for Radiation Protection.


New York Film Festival Downtown

New York Film Festival Downtown was a New York based film festival founded by Tessa Hughes-Freeland and Ela Troyano in 1984.
Known for its independent and "positively avante-garde" programming, the festival came to prominence in the East Village art scene. The New York Film Festival Downtown ran for five years, ending in 1988.


7S (music)


Q-statistic

The Q-statistic is a test statistic output by either the Box-Pierce test or, in a modified version which provides better small sample properties, by the Ljung-Box test. It follows the chi-squared distribution. See also Portmanteau test.
The q statistic or studentized range statistic is a statistic used for multiple significance testing across a number of means: see Tukey–Kramer method.


Pocket comparator

A pocket comparator is an optical device for measuring and inspection comprising a loupe and a reticle. The instrument was developed and manufactured by the Bell & Howell Company, but similar instruments of other names are made by other manufacturers.
It is used for:
Measurements are performed by bringing the surface of the reticle as close as possible to the work inspected.


2260 Neoptolemus

2260 Neoptolemus is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 26 November 1975, by astronomers at the Purple Mountain Observatory in Nanking, China. The dark D-type asteroid is one of the 50 largest Jupiter trojans and has a rotation period of 8.18 hours. It was named after Neoptolemus from Greek mythology.
Orbit and classification.
"Neoptolemus" is a dark Jovian asteroid orbiting in the leading Greek camp at Jupiter's Lagrangian point, 60° ahead of its orbit in a 1:1 resonance "(see Trojans in astronomy)". It is also a non-family asteroid in the Jovian background population.
This asteroid orbits the Sun at a distance of 5.0–5.4 AU once every 11 years and 10 months (4,326 days; semi-major axis of 5.2 AU). Its orbit has an eccentricity of 0.04 and an inclination of 18° with respect to the ecliptic. The body's observation arc begins with its first observation as "" at McDonald Observatory in December 1951, almost 24 years prior to its official discovery observation at Nanking.
Physical characteristics.
In the SDSS-based taxonomy, "Neoptolemus" is a dark D-type asteroid. It has also been characterized as a D-type by the survey conducted by Pan-STARRS, while in the Tholen classification the body's spectral type is ambiguous, closest to a D-type and somewhat similar to a T-type asteroid, with a spectrum flagged as unusual and moderately noisy (DTU:).
Rotation period.
In August 1995, and in March 2002, two rotational lightcurves of "Neoptolemus" were obtained from photometric observations by Italian astronomer Stefano Mottola using the Bochum 0.61-metre Telescope at La Silla Observatory, Chile, and the 1.52-meter Loiano Telescope at the Observatory of Bologna, Italy, respectively. Lightcurve analysis gave a well-defined rotation period of 8.180 hours and a brightness variation of 0.20 and 0.32 magnitude, respectively ().
Follow-up observation by Robert Stephens at the Center for Solar System Studies in 2015, and 2016, gave a concurring period of 8.18 and 8.199 hours with a corresponding amplitude of 0.14 and 0.03 magnitude ().
Diameter and albedo.
According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, "Neoptolemus" measures between 71.65 and 81.28 kilometers in diameter and its surface has an albedo between 0.051 and 0.0650.
The "Collaborative Asteroid Lightcurve Link" adopts the results obtained by IRAS, that is, an albedo of 0.0650 and a diameter of 71.65 kilometers based on an absolute magnitude of 9.31.
Naming.
This minor planet was named from Greek mythology after the Greek warrior Neoptolemus, son of Achilles and Deidameia, who was brought to Troy by Odysseus in the last year of the Trojan War. Neoptolemus was one of the Greeks who were hiding in the wooden Trojan Horse. He brutally killed King Priam and several other princes during the destruction of the city of Troy.
The official naming citation was published by the Minor Planet Center on 1 August 1981 ().


Statute mile


Common Eligibility Test

The Common Eligibility Test (or CET), is an upcoming examination in India to be started from year 2021 for recruitment of staff to non-gazetted posts in the central government and public sector banks and Indian Railways. The test will be conducted by National Recruitment Agency which will function as a central agency of Indian Government . The setting up of the National Recruitment Agency for replacing multiple entrance examination with a single examination was approved by Union Cabinet of India on 19 August 2020..
The National Recruitment Agency shall conduct a separate CET each for the three levels of graduate, higher secondary (12th pass), and the matriculate (10th pass) candidates for various non-technical posts. Presently such tests are being conducted by SSC, IBPS, Railways, and various other organizations.
History.
Presently multiple examinations by various agencies viz. Railways, IBPS, SSC are held for recruiting group B and C staff for various organizations of central govt. In the budget speech of 2020-21, the finance minister Nirmala Sitaraman proposed setting up National Recruitment Agency in order to replace multiple examinations for various govt. job recruitment in India by Central Govt. The upcoming CET will replace all these exams, which will save job seekers time and energy from filling multiple forms and focusing on all the examinations.
Salient Features of NRA and CET.
The CET will be held twice a year and the scores will be valid for the next three years from the date of declaration of result. The best of CET scores will be considered as the current score of the candidate.
Mode of Examination.
The examination will be conducted as online examination, also the candidates will have to apply online for this examination.
This test will be based on a multiple-choice objective type question paper.
No. of Attempts.
There will be no limit on the number of attempts for taking this examination, but the upper age limit will be there. However, the relaxation in the upper age limit shall be given to candidates of SC/ST/OBC and other categories as per the extant policy of the Government.
Exams Replaced by CET.
Here are the top three government exams by which the Common Eligibility Test gets replaced.
Staff Selection Commission (SSC),
NTPC Railway Recruitment Board (RRB), and
Institute of Banking Personnel Selection (IBPS).
Medium of Examination.
The examination will be conducted in 12 languages that are in the Eighth Schedule of the Constitution of India.
Examination Centers.
For the ease of the candidates, each district will have at least one examination center, and in total around 1000 examination centers will be made.
Other features.
The scores of CET will be with central government, state government, union territories, public sector undertakings and private sector, and it can be used for recruitment in their respective departments and agencies /companies.


223 Rosa

Rosa (minor planet designation: 223 Rosa) is a large Themistian asteroid. It is classified as a combination of C-type and P-type asteroids, so it is probably composed of carbonaceous material rich in water ice. It was discovered by Johann Palisa on 9 March 1882, in Vienna. The origin of the name is not known.
Photometric observations made in 2011–2012 at the Organ Mesa Observatory in Las Cruces, New Mexico, produced a light curve with a period of 20.283 ± 0.002 hours and a brightness variation of 0.13 ± 0.02 in magnitude. The curve has two asymmetrical maxima and minima per 20.283-hour cycle.


Nishtala Appala Narasimham

Prof. Nishtala Appala Narasimham, shortly N. A. Narasimham M.Sc., Ph.D. (15 August 1922 – 8 April 2002) was an Indian physicist and eminent Spectroscopist.
He was born at Parlakimidi on 15 August 1922. He was graduated in Physics (B.Sc.) from Andhra University in 1942 and M.Sc. in Physics from Banaras Hindu University (BHU) in 1945. He passed both the examinations with first-class. He has worked as lecturer in Physics in Mrs. A.V.N. College, Visakhapatnam and at Bijapur between 1945 and 1949.
He has joined with R. K. Asundi at BHU in 1949 and obtained his Ph.D. in 1952.
He died in Mumbai on 2002 at the age of 79 years. He is survived by wife Kamala and son Prasad.


C-flat major

C-flat major (or the key of C-flat) is a major scale based on C, consisting of the pitches C, D, E, F, G, A, and B. Its key signature has seven flats. The direct enharmonic equivalent of C-flat major is B major, a key signature with five sharps.
The C-flat major scale is:
C-flat major is the only major or minor key, other than theoretical keys, which has "flat" or "sharp" in its name, but whose tonic note is the enharmonic equivalent of a natural note (a white key on a keyboard instrument).
Its relative minor is A-flat minor (or enharmonically G-sharp minor), and its parallel minor is C-flat minor, usually replaced by B minor, since C-flat minor's three double-flats make it impractical to use.
Use in harp music.
C-flat major is the home key of the harp, with all its pedals in the top position, and it is considered the most resonant key for the instrument. Thus, in Richard Strauss's "Ein Heldenleben", the first cue for the harps is written in C-flat major even though the rest of the orchestra, having previously played in E-flat major, retains a 3-flat key signature and is now playing in B major, marked with the necessary sharps and naturals as accidentals.
This use of C-flat major in harp parts when the rest of the orchestra is playing in B major is not exceptional: it is standard practice in orchestral music written in B major for harp parts to be notated in C-flat major. In Arnold Bax's symphonic poem "Tintagel", the key is B major and again the harp part is always notated in C-flat major; but in this case the harp's key signature contains only 6 flats, and the necessary Fs are notated with accidentals. In Claude Debussy's Sonata for Flute, Viola and Harp, the second movement has a middle section in B major, for which the harp part is notated in C-flat major with seven flats. In Reinhold Glière's Harp Concerto in E-flat major, the middle movement is a set of variations in C-flat major. Sometimes harp parts are also written in G-flat major when the rest of the orchestra is notated in F-sharp major. Harp parts can also be written in A-flat minor when the rest of the orchestra is notated in G-sharp minor.
Music in C-flat major.
Although most composers prefer to use the enharmonic equivalent B major, since it only contains five sharps as opposed to C-flat major's seven flats, the middle section of Frédéric Chopin's "Contredanse" in G-flat major is written in C-flat major, as are the middle (Trio) sections of two of Ernesto Nazareth's Brazilian tangos for piano, "Chave de Ouro" and "Labirinto" (both with a home key of G-flat major), as well as the final half (last two themes) of William Bolcom's rag for piano, "Seabiscuits".
There is a brief passage in the first movement, "Evocación", of "Iberia" by Isaac Albéniz which suggests the key of C-flat minor by adding the necessary three double-flats as accidentals. The surrounding passages are in C-flat major, with a 7-flat key signature. The movement is in sonata form, in the key of A-flat minor, so this places the second theme in the orthodox relative major key (and in the also-orthodox tonic major key of A-flat major when it reappears near the end of the piece).
The slow movement of Ludwig van Beethoven's Piano Sonata No. 12 has a principal theme that modulates from A-flat minor to C-flat major, before moving to what would theoretically be C-flat minor, but is notated as B minor (every note in this passage requires an accidental, due to the key signature of seven flats). A few other works by Beethoven have significant passages in C-flat major, although they usually notate this with accidentals in some other key signature, because Beethoven found C-flat major's seven flats to be a difficult key; for example:
C-flat major is used for Benjamin Britten's "Interlude" in C-flat major for harp, several of Max Reger's Canons in All Major and Minor Keys (Book 1 Nos. 62 and 63, and Book 2 No. 48), and No. 29 from the "Thirty Preludes in All Major and Minor Keys" by Christian Heinrich Rinck.
In some scores, the C-flat major key signature in the bass clef is written with the flat for the F on the second line from the top. This can be seen, for example, in the Albéniz example given above: Iberia, 1st movement: "Evocación", about two-thirds of which is in 7 flats, and every bass-clef staff of which shows this variant. This is also seen in the second movement of the Beautiful Danube waltz in the Boosey & Hawkes concert band edition.


Ideain

Ideain, the cyanidin 3-O-galactoside, is an anthocyanin, a type of plant pigment.
Natural occurrences.
Ideain is the main anthocyanin in red-skinned or red-fleshed (for example Weirouge) apple varieties. It is also found in Chinese hawthorn fruits ("Crataegus spp.").
While it is only one in the many anthocyanins present in bilberries ("Vaccinium myrtillus") and cranberries ("Vaccinium macrocarpon"), it is the main anthocyanin in lingonberries ("Vaccinium vitis-idaea").
"Quintinia serrata", the tawheowheo, a species of evergreen trees endemic to New Zealand, has different patterns of anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-galactoside) in its leaves to protect the shade-adapted chloroplasts from direct sun light.


Decimal dozen


Equivalent Full-Time Student Load


October Revolution in Jazz

The October Revolution in Jazz was a four-day festival of new jazz music which took place at the Cellar Café in New York City. It occurred from October 1–4, 1964, and was organized by composer and trumpeter Bill Dixon. The success of the festival was directly responsible for the formation of the Jazz Composers Guild.
Background.
During a trip to Helsinki, Finland with Archie Shepp in the summer of 1962, Dixon began to develop embouchure difficulties. The situation deteriorated to the point where, by the following summer, Dixon stopped playing in public in order to focus on correcting the issue. He also began concentrating on writing and arranging. Shepp, meanwhile, began collaborating with John Tchicai, with whom he would soon form the New York Contemporary Five. Dixon composed and arranged a number of the pieces that would be performed and recorded by the NYCF, and also managed their weekly rehearsals. By early 1964, Dixon had recovered to the point where he was able to record the A side of the album "Bill Dixon 7-tette/Archie Shepp and the New York Contemporary 5", a split LP with the NYCF that came about in order to fulfill Dixon's and Shepp's contractual obligations to Savoy Records. Dixon, however, was still unhappy with his sound, and stated: "After that record date, when I started freelancing, I needed things to do to make money. I can transcribe, so I began to transcribe Savoy's gospel music to create lead sheets..."
In April 1964, while Dixon was living on 103rd Street in Manhattan and working on the gospel transcriptions, he stumbled on the Cellar Café, a coffee shop located at 251 West 91st Street. The Café, run by Peter Sabino, had opened in late February, and "was serving up an eclectic and inchoate fare of poetry, film, folk music, and jazz for an audience largely of Columbia University students." Dixon recalled: "I happened to come down to 91st Street and saw the Cellar Café. You actually went into the cellar coming off the street. I would have walked on past, but they had a sign up that read 'JAZZ TONIGHT', with the name of a very fine musician, [alto saxophonist] Bobby Brown. So I went in, and Bobby Brown never showed. That's how I met [the club's manager Peter Sabino...]" Dixon described the atmosphere as "very relaxed, like a Viennese coffee house, lots of things going on."
After discussions with Sabino, Dixon soon began arranging and producing concerts at the Café. Between May and September, 1964, Dixon staged a series of concerts at 4 p.m. on Sundays, featuring Paul Bley, the Free Form Improvisation Ensemble, Jimmy Giuffre, and Sun Ra. Dixon stated: "I had let people know when I started doing things at the Cellar that the only groups that I was interested in were those with no other place to play... if they weren't allowed to work anywhere else, the Cellar was open to them. It wasn't up to me to say that these players were either good or bad. I had to have a place where people could come and hear what the musical ferment of their time comprised." Trombonist Roswell Rudd remarked: "You know, they could pay their money and take their chances at the commercial... clubs. But at least here, they were guaranteed a taste of the unexpected, the unforeseen." Dixon also recalled: "You had to have two things to run a club successfully: you had to make it so people could afford to go to the place, and so musicians were comfortable enough to play and not bullshit the public. So right away I let musicians play as long as they wanted... So the place developed an ambience of the music being carried out with integrity." In addition, the Café allowed musicians to rehearse there during the day; according to Dixon, "There wasn't that much work at the time, but people rehearsed incessantly. Rehearsing "was" the work."
At this point, Dixon began planning something more substantial:
One day I went to the operator of the Cellar, Peter Sabino, and he and I came up with the idea for this thing. Sabino and I were going to go into business; we would get a liquor license and open this place as a club, and he wanted to do a concert. I told him everyone does a concert; why don't we do a week-long event, a festival? The festival was going to be an official opening for the club. We had no money, so I got on the phone. For that first festival I ran my telephone bill up to an unheard of amount of $500.00 and stalled the telephone company from turning my service off. I went one solid year without paying my rent. I owed every grocer in the West Village. I was a believer; I believed in this stuff and poured everything I could into the festival and (later) into the Guild operation.
Regarding his motivations, Dixon stated:
I did the "October Revolution" completely by myself – irrespective of what anyone says. I did it for a single reason. I had a point that I had to prove to people. All these writers... were telling me that this music I saw wasn't worth anything, that no one could be interested in it. I knew people could be interested in anything if it was presented to them in the proper way. I "knew" that. And of the people I admired who were in the first wave of this music, the only person who ever lent any moral or philosophical support for the new music was John Coltrane. The rest of them were negative or jealous; they wouldn't help us or endorse what we did..."
By the third week of September, Dixon had finalized the schedule and personnel for the four-day "October Revolution in Jazz", named after the Bolshevik Revolution of 1917. This gave him time to place advance notices in newspapers such as the Columbia Daily Spectator, the Villager, and the Village Voice. The festival was also included in the concert listings of the New York Times, and was mentioned in the October 8 issue of DownBeat. Performances would begin at 4:00 p.m. each day, ending at midnight, at which point there would be panel discussions, moderated by Dixon, with topics such as "Jim Crow and Crow Jim," "The Economics of Jazz," "The Rise of Folk Music and the Decline of Jazz," and "Jazz Composition."
Event schedule.
The following performers appeared at the event:
Reception.
The "October Revolution" was a success on a number of levels. On the afternoon of the first concert, Dixon received a call from Sabino:
[H]e says, "Bill, can you get over here right away?" I said, "Why?" He says, "Just get over here right away." So I went over, and I got downstairs, and there was this huge crowd in the street, between Broadway and West End. So I said, "Gee, I wonder what happened." I got to the Cellar, I walked in, and Peter said, "They're all trying to get in!" That's the way it was, for the entire thing.
According to Val Wilmer, "Dixon had maintained that there was an audience for the new music, at that time still in its infancy, and the nightly turnout that squeezed into the club and spilled out on the sidewalk confirmed this." Total attendance over the four days was roughly seven hundred people. Bernard Gendron wrote:
With advanced advertising in the Village Voice, each of the four nights drew capacity crowds with long lines of people waiting their turn in these marathon events. The audience included a number of jazz musicians, some who came without prompting (Ornette Coleman and Gil Evans), and others who came to participate in the panel discussions (Cecil Taylor, Archie Shepp, and Steve Lacy, among others). Though spearheaded by relatively unknown musicians performing in an out-of-the-way place, the "October Revolution" created enough of a stir to merit two substantial reviews by DownBeat writers Martin Williams and Dan Morgenstern, in side by side columns...
Writer A. B. Spellman noted: "Almost everybody who's doing anything at all in the way of avant-garde jazz in New York passed through the Cellar during these programs, if not to play, then to participate in the panels or to listen." Roswell Rudd recalled: "I just remember it... [being] very professional. The players were seriously digging in... Serious business... And I don't mean to make it sound like a funeral. It was anything but. What I mean by the word 'focused' is a lot of humor, good feeling, certain amount of good competitiveness. My recollection is very positive." Ekkehard Jost wrote:
With his festival Bill Dixon was able to show, first of all, that there was an enormous pool of musicians in New York who deserved a hearing, and second, that there was a (predominantly young) public which was just as fed up with ossified musical norms – and with the commercial hustle of established jazz clubs too – as were the musicians themselves. The "October Revolution" did nothing to relieve the financial insecurity of free jazz musicians at first. But it did indicate how musicians could take the initiative into their own hands and secure for themselves what the establishment – content to earn on Brubeck and Peterson – denied them.
Impact.
Writer Bill Shoemaker called the "October Revolution in Jazz" "arguably the most seminal jazz concert series ever held" and stated that it "marked the beginning of the Golden Era of do-it-yourself jazz culture in the U.S." The success of the "October Revolution" led directly to the formation of the Jazz Composers Guild. Val Wilmer wrote: "Dixon discussed with Cecil Taylor the possibilities of forming an organization that would protect the jazz musician/composer from the exploitation that had hitherto prevailed. 'You can't kill an organisation, but you can kill an individual,' said Dixon..." Dixon also declared that the purpose of the Guild was "to establish the music to its rightful place in society; to awaken the musical conscience of the masses of people to that music which is essential to their lives; to protect musicians and composers from the existing forces of exploitation; to provide an opportunity for the audience to hear the music; to provide facilities for the proper creation, rehearsal, performance, and dissemination of the music." In mid-October, the following announcement appeared:
THE OCTOBER REVOLUTION CONTINUES: musicians-composers Cecil Taylor, Archie Shepp, Sun Ra, Mike Mantler, Burton Greene, Roswell Rudd, John Tchicai, and Bill Dixon have united as the JAZZ COMPOSERS GUILD with the idea in mind that the music as represented by the above-named and others must and will no longer remain a part of the "underground" scene.
(These musicians, along with Paul and Carla Bley, would form the core membership of the Jazz Composers Guild.) The following weeks saw a series of Guild-sponsored concerts, featuring the Sun Ra Arkestra, the Roswell Rudd-John Tchicai Quartet (later renamed the New York Art Quartet), the Paul Bley Quintet, the Alan Silva Quartet, the Cecil Taylor Unit, the Bill Dixon Sextette, the Free Form Improvisation Ensemble, and the Archie Shepp Septette, at the Cellar Café and several other locations. One of these concerts, called the "Pre-Halloween Jazz Party," ran from 9:00 p.m. – 6:00 a.m. on October 30–31 and was put on "to raise funds to provide a permanent home for the Guild." These concerts were followed by the Guild's most visible event, a four-day series called "Four Days in December", running from December 28–31 at Judson Hall. Participants were the Cecil Taylor Unit, the Bill Dixon Sextette, the Paul Bley Quintet, the Jazz Composer's Guild Orchestra, the Free Form Improvisation Ensemble, the Archie Shepp Quartet, the Roswell Rudd-John Tchicai Quartet, and the Sun Ra Arkestra. According to Ingrid Monson, "The first night pulled a standing-room-only crowd of 300, while the remaining nights drew about 150 each. In any case, the success of these two concert series served as a basis for optimism about the possibilities of alternative means of organizing musical events."
The Guild soon abandoned the Cellar Café when the owner of the building more than doubled the rent. The Café was also issued a summons for presenting music without a proper license, and closed its doors. The Guild itself proved to be short-lived, but did "light the way for the organisations that were to follow," such as the Jazz and People's Movement, the Collective Black Artists group, and the AACM.
Tributes.
In 1994, in celebration of the thirty-year anniversary of the "October Revolution in Jazz", Rashied Ali (who had participated in the 1964 concerts), Borah Bergman, Joe McPhee, Wilber Morris, and the Myra Melford Trio recorded an album titled "The October Revolution", released on the Evidence label.


Fourth (angle)


Yuma Proving Ground

Yuma Proving Ground (YPG) is a United States Army proving ground and one of the largest military installations in the world. It is a subordinate command of the Army Test and Evaluation Command.
Located in southwestern La Paz County and western Yuma County in southwestern Arizona, United States, approximately north-east of the city of Yuma, it encompasses 1,307.8 square miles (3,387.2 km²) in the northwestern Sonoran Desert.
Overview.
The proving ground conducts tests on nearly every weapon in the ground combat arsenal. Nearly all the long-range artillery testing for U.S. ground forces takes place here in an area almost completely removed from urban encroachment and noise concerns. Restricted airspace controlled by the test center amounts to over . Yuma Proving Ground has the longest overland artillery range () in the nation, the most highly instrumented helicopter armament test range in the Department of Defense, over of improved road courses for testing tracked and wheeled military vehicles, over of fiber-optic cable linking test locations, and the most modern mine and demolitions test facility in the western hemisphere. Realistic villages and road networks representing urban areas in Southwest Asia have been constructed and are used for testing counter-measures to the threat of roadside bombs.
The General Motors Desert Proving Ground – Yuma opened at the proving ground in late July 2009. General Motors built the facility at a cost of more than $100 million after closing its desert automotive test facility in Mesa, Arizona, that had been in operation since 1953. The new facility allows Army automotive testers to test their wheeled vehicles all year-round. It is estimated that the track can be used to test about 80 percent of the Army's wheeled vehicle fleet.
More than 3,000 people, mostly civilians, work at the proving ground, which is the largest employer in Yuma County.
In a typical year, over 500,000 artillery, mortar and missile rounds are fired, 36,000 parachute drops take place, are driven on military vehicles, and over 4,000 air sorties are flown from the proving ground's Laguna Army Airfield.
About 10 percent of the proving ground's workload is training. In a typical year, dozens of units come to the facility for realistic desert training, especially before deploying overseas.
Yuma Proving Ground's clean air, low humidity, skimpy rainfall – only about per year – and annual average of 350 sunny days, add up to almost perfect testing and training conditions. Urban encroachment and noise concerns are nonexistent problems, unlike at many other military installations.
Of the four extreme natural environments recognized as critical in the testing of military equipment, three fall under the management authority of Yuma Proving Ground. Realistic natural environment testing ensures that American military equipment performs as advertised, wherever deployed around the world. The proving ground manages military equipment and munitions testing at three locations: The Cold Regions Test Center (CRTC) at Fort Greely, Alaska; the Tropic Regions Test Center (TRTC) operating in Panama, Honduras, Suriname, and Hawaii; and at the Yuma Test Center (YTC) located at Yuma Proving Ground. The common link between these test centers is "environmental testing," which makes the proving ground the Army's environmental test expert.
Yuma Proving Ground tests improvised explosive devices, commonly known as IEDs, the number-one killer of American service men and women in Iraq and Afghanistan. Hundreds of unmanned aerial vehicles fly at the proving ground each year from the six airfields located at the proving ground, as do helicopters and fixed-wing aircraft conducting personnel and cargo parachute drops.
Many friendly foreign nations also visit the proving ground to conduct test programs.
History.
The presence of the U.S. Army in Yuma goes back to 1850, when Fort Yuma was constructed on a hill overlooking the important Yuma crossing of the Colorado River. Soldiers at Fort Yuma maintained peace and protected the important Yuma crossing, which was used by thousands of travelers each year.
The Army constructed a second facility in 1865, the Yuma Quartermaster Depot, to act as a supply base for Army posts throughout Arizona and parts of New Mexico. Supplies were delivered by riverboats and transported from the depot to military outposts by wagon. After Fort Yuma and the Yuma Quartermaster Depot closed in the 1880s, the Army did not return to Yuma on a permanent basis until World War II.
Yuma Proving Ground traces its history to Camp Laguna and the Army Corps of Engineers Yuma Test Branch, both activated in 1943. Located on the Colorado River, the Yuma Test Branch conducted testing on combat bridges, amphibious vehicles, and boats. Tens of thousands of mechanized and infantry soldiers were trained at Camp Laguna for duty at combat fronts throughout the world, from North Africa to the South Pacific. Abandoned campsites and tank trails can still be found on the proving ground.
Camp Laguna lasted only until the end of World War II. The Yuma Test Branch was closed in 1949 and reactivated two years later as the Yuma Test Station, under the operational control of the Sixth U.S. Army. In 1962, the station was named Yuma Proving Ground and reassigned to the U. S. Army Materiel Command as an important component of the Test and Evaluation Command. On July 26, 1973, it officially received its full name – U.S. Army Yuma Proving Ground. The following year it was designated as a Department of Defense Major Range and Test Facility Base.
Since its early days, Yuma Proving Ground has been a desert environmental test center for all types of military equipment and materiel. However, developmental and a variety of other types of testing of artillery systems and ammunition, aircraft armament and targeting systems, mobility equipment, and air delivery systems, not necessarily desert environmental-related, now comprise the bulk of the workload. A heavy investment in technology and a highly skilled soldier-civilian workforce makes the proving ground a significant social and economic component of the local community.
Yuma Test Center.
YTC offers the following for test, evaluation, and training purposes:


Triple beam balance

The triple beam balance is an instrument used to measure mass very precisely. Such devices typically have a reading error of ±0.05 grams. Its name refers to its three beams, where the middle beam is the largest, the far beam of medium size, and the front beam the smallest. The difference in size of the beams indicates the difference in weights and reading scale that each beam measures. Typically, the reading scale of the middle beam reads in 100 gram increments, the far beam in 10 gram increments, and the front beam can read from 0 to 10 grams. The triple beam balance can be used to measure mass directly from the objects, find mass by difference for liquid, and measure out substances.
Parts of a triple beam balance.
The parts of triple beam balance are identified as the following.
Before using triple beam balance, the scale pointer should be at zero. The zero adjustment knob can be used to adjust the scale pointer. Place the objects on the pan and adjust the riders. The hundred rider should be initially adjusted and follow by the tens rider. Adjust the ones rider until the scale pointer is at zero again.


Gouy balance

The Gouy balance, invented by Louis Georges Gouy, is a device for measuring the magnetic susceptibility of a sample.
Background.
Amongst a wide range of interest in optics, Brownian motion, and experimental physics, Gouy also had a strong intrigue for the phenomena of magnetism. Gouy derived a mathematical expression showing that force is proportional to volume susceptibility for the interaction of material in a uniform magnetic field in 1889. From this derivation, Gouy proposed that balance measurements taken for tubes of material suspended in a magnetic field could evaluate his expression for volume susceptibility. Though Gouy never tested the scientific suggestion himself, this simple and inexpensive method became the foundation for measuring magnetic susceptibility and the blueprint for the Gouy balance.
Procedure.
The Gouy balance measures the apparent change in the mass of the sample as it is repelled or attracted by the region of high magnetic field between the poles. Some commercially available balances have a port at their base for this application.
In use, a long, cylindrical sample to be tested is suspended from a balance, partially entering between the poles of a magnet. The sample can be in solid or liquid form, and is often placed in a cylindrical container such as a test tube. Solid compounds are generally ground into a fine powder to allow for uniformity amongst the sample. The sample is suspended between the magnetic poles through an attached thread or string.
The experimental procedure requires two separate reading to be performed. An initial balance reading is performed on the sample of interest without a magnetic field (m a). A subsequent balance reading is taken with an applied magnetic field (mb). The difference between these two readings relates to the magnetic force on the sample (mb – ma).
Concept.
The apparent change in mass from the two balance readings is a result of magnetic force on the sample. The magnetic force is applied across the gradient of a strong and weak magnetic field. A sample with a paramagnetic compound will be pulled down towards the magnetic, and provide a positive difference in apparent mass mb – ma. Diamagnetic compounds can either exhibit no apparent change in weight or a negative change as the sample is slightly repelled by the applied magnetic field. With a paramagnetic sample, the magnetic induction is stronger than the applied field and magnetic susceptibility is positive. A diamagnetic sample has a magnetic induction much weaker than the applied field, and a respective negative magnetic susceptibility. The following mathematical equation relates the apparent change in mass to the volume susceptibility of the sample:
formula_1
Instrument.
In a practical device, the whole assembly of balance and magnet is enclosed in a glass box to ensure that the weight measurement is not affected by air currents. The sample can also be enclosed in a thermostat in order to make measurements at different temperatures. Since it requires a large and powerful electromagnet, the Gouy balance is a stationary instrument permanently set up on a bench. The apparatus is often placed on a marble balance table in a non-ventilated room to minimize the vibrations and disruption from the environment. The stationary magnetic of a Gouy balance is often an electromagnet connected to a power source, since balance recordings with and without the applied magnetic field are required of the procedure.


List of largest lakes of the United States by area

The following is a list of the largest 100 lakes of the United States by normal surface area. The top twenty lakes in size are as listed by the "National Atlas of the United States", a publication of the United States Department of the Interior. The area given is the normal or average area of the lake. The area of some lakes fluctuates substantially. For those lakes partially in Canada or Mexico the area given for the lake is the total area, not just the part of the lake in the United States. Of the top 100 lakes, 55 are man-made and 45 are natural. Three lakes in the top 100 are primarily salt water.