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Mach–Zehnder interferometer

In physics, the Mach–Zehnder interferometer is a device used to determine the relative phase shift variations between two collimated beams derived by splitting light from a single source. The interferometer has been used, among other things, to measure phase shifts between the two beams caused by a sample or a change in length of one of the paths; the apparatus is named after the physicists Ludwig Mach and Ludwig Zehnder: Zehnder's proposal in an 1891 article was refined by Mach in an 1892 article. The Mach–Zehnder check interferometer is a configurable instrument. In contrast to the well-known Michelson interferometer, each of the well-separated light paths is traversed only once. If it is decided to produce fringes in white light since white light has a limited coherence length, on the order of micrometers, great care must be taken to equalize the optical paths over all wavelengths, or no fringes will be visible; as seen in Fig. 1, a compensating cell made of the same type of glass as the test cell would be placed in the path of the reference beam to match the test cell.

Note the precise orientation of the beam splitters. The reflecting surfaces of the beam splitters would be oriented so that the test and reference beams pass through an equal amount of glass. In this orientation, the test and reference beams each experience two front-surface reflections, resulting in the same number of phase inversions; the result is that light traveling an equal optical path length in the test and reference beams produces a white light fringe of constructive interference. Collimated sources result in a nonlocalized fringe pattern. Localized fringes result. In Fig. 2, we see. In most cases, the fringes would be adjusted to lie in the same plane as the test object, so that fringes and test object can be photographed together; the Mach–Zehnder interferometer's large and accessible working space, its flexibility in locating the fringes has made it the interferometer of choice for visualizing flow in wind tunnels and for flow visualization studies in general. It is used in the fields of aerodynamics, plasma physics and heat transfer to measure pressure and temperature changes in gases.

Mach–Zehnder interferometers are used in electro-optic modulators, electronic devices used in various fiber-optic communication applications. Mach–Zehnder modulators are incorporated in monolithic integrated circuits and offer well-behaved, high-bandwidth electro-optic amplitude and phase responses over a multiple-gigahertz frequency range. Mach–Zehnder interferometers are used to study one of the most counterintuitive predictions of quantum mechanics, the phenomenon known as quantum entanglement; the possibility to control the features of the light in the reference channel without disturbing the light in the object channel popularized the Mach–Zehnder configuration in holographic interferometry. In particular, optical heterodyne detection with an off-axis, frequency-shifted reference beam ensures good experimental conditions for shot-noise limited holography with video-rate cameras and laser Doppler imaging of blood flow. A collimated beam is split by a half-silvered mirror; the two resulting beams are each reflected by a mirror.

The two beams pass a second half-silvered mirror and enter two detectors. The Fresnel equations for reflection and transmission of a wave at a dielectric imply that there is a phase change for a reflection, when a wave propagating in a lower-refractive index medium reflects from a higher-refractive index medium, but not in the opposite case. A 180° phase shift occurs upon reflection from the front of a mirror, since the medium behind the mirror has a higher refractive index than the medium the light is traveling in. No phase shift accompanies a rear-surface reflection, since the medium behind the mirror has a lower refractive index than the medium the light is traveling in; the speed of light is lower in media with an index of refraction greater than that of a vacuum, 1. Its speed is: v = c/n, where c is the speed of light in vacuum, n is the index of refraction; this causes a phase shift increase proportional to × length traveled. If k is the constant phase shift incurred by passing through a glass plate on which a mirror resides, a total of 2k phase shift occurs when reflecting from the rear of a mirror.

This is because light traveling toward the rear of a mirror will enter the glass plate, incurring k phase shift, reflect from the mirror with no additional phase shift, since only air is now behind the mirror, travel again back through the glass plate, incurring an additional k phase shift. The rule about phase shifts applies to beamsplitters constructed with a dielectric coating and must be modified if a metallic coating is used or when different polarizations are taken into account. In real interferometers, the thicknesses of the beamsplitters may differ, the path lengths are not equal. Regardless, in the absence of absorption, conservation of energy guarantees that the two paths must differ by a half-wavelength phase shift. Note that beamsplitters that are not 50/50 are employed to improve the interferometer's performance in certain types of measurement. In Fig. 3, in the absence of a sample, both the sample beam SB and the reference beam RB will arrive in phase at detector 1, yielding constructive interference.

Both SB and RB will have undergone a phase shift of due to two front-surface reflections and one transmission through a glas

Second Matabele War

The Second Matabele War known as the Matabeleland Rebellion or part of what is now known in Zimbabwe as the First Chimurenga, was fought between 1896 and 1897 in the area known as Rhodesia, now Zimbabwe. It pitted the British South Africa Company against the Matabele people, which led to conflict with the Shona people in the rest of Rhodesia. In March 1896, the Matabele revolted against the authority of the British South Africa Company; the Mlimo the Matabele spiritual leader, is credited with fomenting much of the anger that led to this confrontation. He convinced the Matabele and the Shona that the settlers were responsible for the drought, locust plagues and the cattle disease rinderpest ravaging the country at the time; the Mlimo's call to battle was well-timed. Only a few months earlier, the British South Africa Company's Administrator General for Matabeleland, Leander Starr Jameson, had sent most of his troops and armaments to fight the Transvaal Republic in the ill-fated Jameson Raid.

This left the country nearly defenceless. The British sent troops to suppress the Matabele and the Shona, but it cost the lives of many on both sides. Months passed before the British forces were strong enough to break the sieges and defend the major settlements, war raged on until October of the following year; the Mlimo planned to wait until the night of 29 March, the first full moon, to take Bulawayo by surprise after a ceremony called the Big Dance. He promised, through his priests, that if the Matabele went to war, the bullets of the settlers would change to water and their cannon shells would become eggs, his plan was to kill all of the settlers in Bulawayo first, but not to destroy the town itself as it would serve again as the royal kraal for the newly reincarnated King Lobengula. The Mlimo decreed that the settlers should be attacked and driven from the country through the Mangwe Pass on the Western edge of the Matobo Hills, to be left open and unguarded for this reason. Once the settlers were purged from Bulawayo, the Matabele and Shona warriors would head out into the countryside and continue the slaughter until all the settlers were either killed or had fled.

However, several young Matabele were overly anxious to go to war, the rebellion started prematurely. On 20 March, Matabele rebels stabbed a native policeman. Over the next few days, other outlying settlers and prospectors were killed. Frederick Selous, the famous big-game hunter, had heard rumours of settlers in the countryside being killed, but he thought it was a localised problem; when news of the policeman's murder reached Selous on 23 March, he knew the Matabele had started a massive uprising. Nearly 2,000 Matabele warriors began the rebellion in earnest on 24 March. Many, although not all, of the young native police deserted and joined the rebels; the Matabele headed into the countryside armed with a variety of weapons, including: Martini-Henry rifles, Winchester repeaters, Lee-Metfords, assegais and battle-axes. As news of the massive rebellion spread, the Shona joined in the fighting, the settlers headed towards Bulawayo. Within a week, 141 settlers were slain in Matabeleland, another 103 killed in Mashonaland, hundreds of homes and mines were burned.

A tragic case occurred at the Insiza River where Mrs. Fourie and her 6 small children were found mutilated beyond recognition on their farmstead. Two young women of the Ross family living near by were killed in their newly built home. With few troops to support them, the settlers built a laager of sandbagged wagons in the centre of Bulawayo on their own. Barbed wire was added to Bulawayo's defences. Oil-soaked fagots were arranged in strategic locations in case of attack at night. Blasting gelatin was secreted in outlying buildings that were beyond the defence perimeter, to be exploded in the event the enemy occupied them. Smashed glass bottles were spread around the front of the wagons. Except for hunting rifles, there were few weapons to be found in Bulawayo. For settlers, there were a few working artillery pieces and a small assortment of machine guns. Rather than wait passively, the settlers mounted patrols, called the Bulawayo Field Force, under such figures as Selous and Frederick Russell Burnham.

Selous raised a mounted troop of forty men to scout southward into the Matobo Hills. Maurice Gifford, along with 40 men, rode east along the Iniza River. Whenever settlers were found, they were loaded into their wagons and guarded on their way to Bulawayo. Within the first week of fighting, 20 men of the Bulawayo Field Force were killed and another 50 were wounded. In the First Matabele War, the Matabele had experienced the effectiveness of the settlers' Maxim guns, so they never mounted a significant attack against Bulawayo though over 10,000 Matabele warriors could be seen near the town. Conditions inside Bulawayo, however became unbearable. During the day, settlers could go to homes and buildings within the town, but at night they were forced to seek shelter in the much smaller laager. Nearly 1,000 women and children were crowded into the city, false alarms of attacks were common. Although they kept up their siege, the Matabele made one critical error: they neglected to cut the telegraph lines connecting Bulawayo to Mafeking.

This gave both the relief forces and the besieged Bulawayo Field Force far more information than they would otherwise have had. Several relief columns were organised to break the siege, but the long trek through hostile countryside took several months. Late in May, the first two relief columns app

Pollinator decline

Pollinator decline refers to the reduction in abundance of insect and other animal pollinators in many ecosystems worldwide, beginning at the end of the 20th century, continuing into the present. The U. S. government has stated. As depicted by Pat Thomas in the Ecologist, in the United States alone, bees contribute to $15 billion in crop value. Pollinators participate in the sexual reproduction of many plants, by ensuring cross-pollination, essential for some species and a major factor in ensuring genetic diversity for others. Since plants are the primary food source for animals, the reduction or possible disappearance of primary pollination agents has been referred to as "ecological Armageddon', due to the dire nature of the consequences to world food production; the exact magnitude of the problem is the source of robust ongoing debate, it is fair to say that most, but not all, data comes from honeybees and bumblebees in Europe and North America. Some species are doing better than others, some are stable, some are increasing, such as managed honey bee colonies.

But most evidence points towards "significant declines in pollinator abundance and diversity at multiple spatial scales across all regions". Probable explanations for the decline in pollinators can be attributed to the use of pesticides, habitat destruction, air pollution, climate change, the effects of monoculture, competition between native and introduced or invasive species. Pollinators, which are necessary for 75% of food crops, are declining globally in both abundance and diversity. Bees, in particular, are thought to be necessary for the fertilization of up to 90% of the world's 107 most important human food crops; the decline in bee numbers has attracted much public attention. Members of the British Beekeepers' Association have issued numerous warnings in the 21st century that the country's bees are in rapid decline. Writing in 2013, Elizabeth Grossman noted that the winter losses of beehives had increased in recent years in Europe and the United States, with a hive failure rate up to 50%.

In France, the honey harvest for 2017 has been estimated at around 10,000 tons, representing a decline of two-thirds against the average annual harvest during the 1990s. A 2017 study led by Radboud University's Hans de Kroon, using 1,500 samples from 63 sites, indicated that the biomass of insect life in Germany had declined by three-quarters in the previous 25 years. Participating researcher Dave Goulson of Sussex University stated that their study suggested that humans are making large parts of the planet uninhabitable for wildlife. Goulson characterized the situation as an approaching "ecological Armageddon", adding that "if we lose the insects everything is going to collapse". Lynn Dicks at the University of East Anglia in 2017 estimated the rate of decline in flying insect biomass at 6% a year; the decline has been termed by entomologists as the windshield phenomenon, since it is associated with anecdotal reports that far fewer insects end up on car windshields now than a few decades ago.

The value of animal pollination in human nutrition and food for wildlife is immense and difficult to quantify. An estimated 87.5% of the world's flowering plant species are animal-pollinated, 35% of crop production and 60% of crop plant species depend on animal pollinators. This includes the majority of fruits, many vegetables, secondary effects from legumes such as alfalfa and clover fed to livestock. In 2000, Drs. Roger Morse and Nicholas Calderone of Cornell University attempted to quantify the effects of just one pollinator, the western honey bee, on only US food crops, their calculations came up with a figure of US$14.6 billion in food crop value. In 2009, another study calculated the worldwide value of pollination to agriculture, they calculated the costs using the proportion of each of 100 crops that need pollinators that would not be produced in case insect pollinators disappeared completely. The economic value of insect pollination was of €153 billion. Several large-scale studies have looked at the nutritional consequences of pollinator decline.

Since pollinators are responsible for propagating certain plants and crops, populations that are reliant on those crops are at risk for malnutrition. As such, the size of the effect that pollinator decline has on an area depends on the local diet. According to a 2015 study published in the Public Library of Science, pollinator decline is most to have negative impacts on the nutritional health of an area when the people living there get the majority of their nutrients from crops that are dependent on pollinators, the affected people are not severely deficient in a nutrient or consuming higher amounts of the nutrient than is recommended, they do not have access to other foods that could substitute the nutrients from the crops they are losing, they do not have access to supplements, fortified foods, or targeted nutrition programs that could help ensure they are still getting adequate nutrients. In contrast, populations whose diets are not based on pollinator-dependent crops will not be affected by pollinator decline to the same extent.

A 2015 study done by the Harvard School of Public Health modeled what would happen should 100% of pollinators die off. In that scenario, 71 million people in low-income countries would become deficient in vitamin A, the vitamin A intake of 2.2 billion people who are consuming less than the recommended amount would further decline. 173 million people would become deficient in folate, 1.23 million people would further lessen their intake. Additionally, the global fruit supply would decrease by 22.9%, the global vege


The FE-Schrift or Fälschungserschwerende Schrift is a sans serif typeface introduced for use on licence plates. Its monospaced letters and numbers are disproportionate to prevent easy modification and to improve machine readability, it has been developed in Germany where it has been mandatory since November 2000. The abbreviation "FE" is derived from the compound German adjective "fälschungserschwerend" combining the noun "Fälschung" and the verb "erschweren". "Schrift" means font in German. Other countries have introduced the same or a derived typeface for license plates taking advantage of the proven design for the FE-Schrift; the motivation for the creation of the typeface arose in the late 1970s in the light of Red Army Faction terrorism when it was discovered that with the then-standard font for vehicle registration plates—the DIN 1451 font—it was easy to modify letters by applying a small amount of black paint or tape. For example, it was easy to change a "P" to an "R" or "B", a "3" to an "8", or an "L" or "F" to an "E".

Modifications to FE-font plates are somewhat more difficult, as they require the use of white paint, distinguished at a distance from the retroreflective white background of the plate, in particular at night. The original design for the FE-Schrift typeface was created by Karlgeorg Hoefer, working for the Bundesanstalt für Straßenwesen at the time; the typeface was modified according to the results of tests that lasted from 1978 to 1980 at the University of Giessen. For example the initial slashed zero Ø letter could be mistaken for an 8, so it needed to be replaced with Karlgeorg Hofer to propose a design with a reduced white slash in the upper right corner. Whilst the DIN typeface was using a proportional font, the FE-Schrift is a monospaced font for improved machine readability. Faked FE-Schrift letters appear conspicuously disproportionate. Another motivation for the new typeface came from a spike in the theft rate of license plates in the early 1970s, and despite the requirement to hinder falsification, the scope document did list that point only in the second place.

The first priority was a requirement for readability by humans and machines as the decade was the same that saw the development of other typefaces for optical character recognition, namely OCR-A and OCR-B. The RAF terrorism however allowed to fund a project over a couple of years — running from the functional scope document being created in 1977 to the final decision of 1982 to not introduce the design on license plates, it ended up in the drawer. The final publication in German law for the usage on license plates includes three variants – normal script with 75 mm high and 47.5 mm wide letters and 44.5 mm wide digits, narrow script with 75 mm high and 40.5 mm wide letters and 38.5 wide digits and a small script with 49 mm high and 31 mm wide letters and 29 mm wide digits. The legal typeface includes umlaut vowels as these occur in German county codes at the start of the license plate number; the narrow font allows nine characters to be put on a standard Euro license plate — shorter numbers are supposed to be printed with larger spaces between characters as to fill the available space on the plate.

The German law defines the font in "Anlage 4" of the "Fahrzeugzulassungsverordnung". In section 2.1 it shows three names for it as "fälschungserschwerende Schrift", "FE-Schrift" and „Schrift für Kfz-Kennzeichen“ with the latter to be used for requesting templates from the "Bundesanstalt für Straßenwesen". Digital variants have never been published by them but there exist third party digitilizations for free download, for example the font "Euro Plate"; the Swiss foundry Lineto has published an extended script that covers the full range of Latin letters inspired by the FE Schrift under the names FE Mittelschrift and FE Engschrift. When the FE-Schrift was finished in 1980 the pressure for its adoption had lessened already, its distribution was furthered by another event being the introduction of the Euro license plate. With the fall of the iron curtain there was again a spike in the theft rate of license plates, including cars being stolen and moved to Eastern Europe. Again there was a motivation to prevent that with new regulations on license plates.

In the new process the officials found the FE-Schrift, developed and a perfect match for the automatic number-plate recognition technology that had developed to a usable state at the time. Some of the federal states in the eastern part of Germany introduced the new design during 1994 in anticipation of the national resolution. In January 1995 it was introduced nationwide by a federal law that came to include the FE-Schrift as well as it had been in the planning since the 1970s; the shift in legislation matches with the first Schengen zone to lift borders during 1995. With the extension of the Schengen zone in 1998 the new license plate design found EU-wide acceptance thereby lifting the older requirement of adding an extra country code plate on the car when roaming to other countries which constitutes an advantage to citizens. Shortly the option to be issued an old license plate design were dropped on 1 November 2000 and the legislation dropped the older typeface for license plates alongside.

The FE-Schrift is mandatory in Germany since

Timothy Binkley

Timothy Binkley, is an American philosopher and teacher, known for his radical writings about conceptual art and aesthetics, as well as several essays that help define computer art. He is known for his interactive art installations. Timothy Binkley studied mathematics at University of Colorado at Boulder, earning a B. A. and an M. A.. His PhD in philosophy, from University of Texas at Austin, explored Ludwig Wittgenstein's use of language. Binkley has lectured and taught at several colleges and universities in the United States, most notably at School of Visual Arts where he initiated the MFA Computer Art program, the first of its kind in the country. In 1992, he founded an international exhibition of computer art, he has exhibited his interactive art in the United States, South America, Asia. Binkley postulates that twentieth-century art is a self-critical discipline, which creates ideas free of traditional piece-specifying conventions including aesthetic parameters and qualities; the artwork is a piece, a piece isn't an aesthetic object—or an object at all.

Binkley states that anything that can be thought about or referred to can be labeled an artwork by an artist. Binkley argues that the computer is neither a medium nor a tool, since both media and tools have inherent characteristics that can be explored through an artist's gestures or physical events for mark-making. Instead, the computer is a chameleon-like or promiscuous assistant, whose services can be applied to any number of tasks and whose capabilities can be defined endlessly from application to application. Binkley refers to the computer as an incorporeal metamedium, yet the computer contains phenomena not found in other media: namely, a conceptual space where symbolic content can be modified using mathematical abstractions. The notion of an “original” and its consequent value are considered irrelevant, obsolete, or inapplicable to computer art. Binkley's philosophy extends beyond art and aesthetics to culture itself, whose foundations he believes we are overhauling through our involvement with computers.

Symmetry Studio: Computer-Aided Surface Design. New York: Van Nostrand Reinhold, 1992. With John F. Simon Jr.. Includes surface design software on CD. Wittgenstein's Language; the Hague: Martinus Nijhoff, 1973. “A Philosophy of Computer Art by Lopes, Dominic McIver”, Journal of Aesthetics and Art Criticism 68,: 409–411. "Autonomous Creations: Birthing Intelligent Agents", Leonardo, 31, Sixth Annual New York Digital Salon,: 333–336. "The Vitality of Digital Creation", The Journal of Aesthetics and Art Criticism, 55, Perspectives on the Arts and Technology.: 107–116. "Computer Art" and "Digital Media", Encyclopedia of Aesthetics, New York: Oxford University Press, 1998. 1:412–414, 2:47–50. “Transparent Technology: The Swan Song of Electronics", Leonardo, 28, Special Issue "The Third Annual New York Digital Salon": 427–432. "Creating Symmetric Patterns with Objects and Lists", Symmetry: Culture and Science, 6. "Refiguring Culture", Future Visions: New Technologies of the Screen, London: British Film Institute Publications,: 90–122.

"Postmodern Torrents", Millennium Film Journal, 23/24: 130–141. "The Computer is Philosophic Exchange. Reprinted in EDB & kunstfag, Rapport Nr. 48, NAVFs EDB-Senter for Humanistisk Forskning. Translated as "L'ordinateur n'est pas un médium", Esthétique des arts médiatiques, Sainte-Foy, Québec: Presses de l'Université du Québec, 1995. "Computed Space", National Computer Graphics Association Conference Proceedings,: 643–652. "Piece: Contra Aesthetics", Philosophy Looks at the Arts: Contemporary Readings in Aesthetics, 3rd Ed. edited by Joseph Margolis. Published in The Journal of Aesthetics and Art Criticism, 35,: 265–277. A French translation appeared in Poétique 79 and has been collected in Esthétique et Poétique, edited by Gérard Genette. Anthologized in The Philosophy of the Visual Arts, edited by Philip Alperson, A Question of Art, edited by Benjamin F. Ward. "Conceptual Art: Appearance and Reality", Art In Culture, 1, edited by A. Balis, L. Aagaard-Mogensen, R. Pinxten, F. Vandamme. Proceedings of the Ghent colloquium "Art in Culture.""Deciding About Art", Culture and Art, edited by Lars Aagaard-Mogensen.

Rest Rooms, interactive telecommunications installation with video-conferenced computers, exhibited at SIGGRAPH ’94 in Orlando, FL. Wexner Center for the Arts in Columbus, OH, Schloss Agathenberg in Germany, Schloß Arolsen in Germany. Books of Change, interactive computer installation exhibited in "Tomorrow's Realities", SIGGRAPH 1994. Included in the "Multimedia Playground" at the Exploratorium in San Francisco. Exhibited at the Hong Kong Arts Centre in Hong Kong, the Central Academy of Art and Design in Beijing, Camera Obscura in Tel Aviv. Watch Yourself, interactive computer installation. Included in "Tomorrow's Realities" exhibit at SIGGRAPH'91 in Las Vegas. Exhibited at the National Conference on Computing and Values, New Haven. Accepted for Ars Electronica in Linz, Austria. Exhibited at Videobrasil Inter

Union Hill-Novelty Hill, Washington

Union Hill-Novelty Hill is a census-designated place in King County, United States. The area was first recognized by the Census Bureau in the 2000 census; the population was 18,805 at the 2010 census. Based on per capita income, Union Hill-Novelty Hill ranks 5th of 522 areas in the state of Washington to be ranked. Union Hill-Novelty Hill is located in northern King County at 47°40′43″N 122°2′57″W, it is bordered to the west by the city of Redmond, a separate portion of the city, comprising the Redmond Watershed Preserve, is surrounded by the northern part of the CDP. To the north is the Cottage Lake CDP, Washington State Route 202 runs along the southern edge of the community in the valley of Evans Creek and Patterson Creek; the Ames Lake CDP is to the southeast, downtown Seattle is 20 miles to the southwest. According to the United States Census Bureau, the Union Hill-Novelty Hill CDP has a total area of 24.3 square miles, of which 24.2 square miles are land and 0.1 square miles, or 0.36%, are water.

As of the census of 2000, there were 11,265 people, 3,584 households, 3,103 families residing in the CDP. The population density was 462.9 people per square mile. There were 3,677 housing units at an average density of 151.1/sq mi. The racial makeup of the CDP was 90.77% White, 0.78% African American, 0.39% Native American, 4.25% Asian, 0.06% Pacific Islander, 1.30% from other races, 2.45% from two or more races. Hispanic or Latino people of any race were 3.45% of the population. There were 3,584 households out of which 53.4% had children under the age of 18 living with them, 78.7% were married couples living together, 4.9% had a female householder with no husband present, 13.4% were non-families. 9.0% of all households were made up of individuals and 2.0% had someone living alone, 65 years of age or older. The average household size was 3.14 and the average family size was 3.37. In the CDP the population was spread out with 33.3% under the age of 18, 5.1% from 18 to 24, 31.2% from 25 to 44, 26.0% from 45 to 64, 4.3% who were 65 years of age or older.

The median age was 36 years. For every 100 females there were 106.7 males. For every 100 females age 18 and over, there were 102.5 males. The median income for a household in the CDP was $98,061, the median income for a family was $105,758. Males had a median income of $77,954 versus $46,167 for females; the per capita income for the CDP was $58,285. About 2.3% of families and 2.9% of the population were below the poverty line, including 2.6% of those under age 18 and 3.5% of those age 65 or over