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  • richardmitnick 10:45 am on January 15, 2022 Permalink | Reply
    Tags: "Cuprates": materials that can be viewed as containing anionic copper complexes., "Newly discovered type of ‘strange metal’ could lead to deep insights", "Strange metals": A type of system where charge carriers are bosons-something that's never been seen before., , “Strange metals”: a class of materials that are related to high-temperature superconductors., Boltzmann’s constant: represents the energy produced by random thermal motion., Bosons follow very different rules from fermions., Brown University (US), , , Cooper pairs: a pair of electrons (or other fermions) bound together at low temperatures., Cuprates are most famous for being high-temperature superconductors meaning they conduct electricity with zero resistance at temperatures far above that of normal superconductors., Fermi liquid theory: a theoretical model of interacting fermions that describes the normal state of most metals at sufficiently low temperatures., , , Planck’s constant: relates to the energy of a photon (a particle of light)., This is the first time "strange metal" behavior has been seen in a bosonic system., While electrons belong to a class of particles called fermions Cooper pairs of electrons act as bosons.   

    From Brown University (US): “Newly discovered type of ‘strange metal’ could lead to deep insights” 

    From Brown University (US)

    January 12, 2022

    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    A new discovery could help scientists to understand “strange metals,” a class of materials that are related to high-temperature superconductors and share fundamental quantum attributes with black holes.

    1
    Using a material called yttrium barium copper oxide arrayed with tiny holes, researchers have discovered “strange metal” behavior in a type of system where charge carriers are bosons-something that’s never been seen before.

    Scientists understand quite well how temperature affects electrical conductance in most everyday metals like copper or silver. But in recent years, researchers have turned their attention to a class of materials that do not seem to follow the traditional electrical rules. Understanding these so-called “strange metals” could provide fundamental insights into the quantum world, and potentially help scientists understand strange phenomena like high-temperature superconductivity.

    Now, a research team co-led by a Brown University physicist has added a new discovery to the “strange metal” mix. In research published in the journal Nature [“Signatures of a ‘strange metal’ in a bosonic system”], the team found “strange metal” behavior in a material in which electrical charge is carried not by electrons, but by more “wave-like” entities called Cooper pairs.

    While electrons belong to a class of particles called fermions Cooper pairs of electrons act as bosons, which follow very different rules from fermions. This is the first time “strange metal” behavior has been seen in a bosonic system, and researchers are hopeful that the discovery might be helpful in finding an explanation for how “strange metals” work — something that has eluded scientists for decades.

    “We have these two fundamentally different types of particles whose behaviors converge around a mystery,” said Jim Valles, a professor of physics at Brown and the study’s corresponding author. “What this says is that any theory to explain “strange metal” behavior can’t be specific to either type of particle. It needs to be more fundamental than that.”

    “Strange metals”

    “Strange metal” behavior was first discovered around 30 years ago in a class of materials called cuprates. These copper-oxide materials are most famous for being high-temperature superconductors, meaning they conduct electricity with zero resistance at temperatures far above that of normal superconductors. But even at temperatures above the critical temperature for superconductivity, cuprates act strangely compared to other metals.

    As their temperature increases, cuprates’ resistance increases in a strictly linear fashion. In normal metals, the resistance increases only so far, becoming constant at high temperatures in accord with what’s known as Fermi liquid theory. Resistance arises when electrons flowing in a metal bang into the metal’s vibrating atomic structure, causing them to scatter. Fermi-liquid theory sets a maximum rate at which electron scattering can occur. But strange metals don’t follow the Fermi-liquid rules, and no one is sure how they work. What scientists do know is that the temperature-resistance relationship in strange metals appears to be related to two fundamental constants of nature: Boltzmann’s constant, which represents the energy produced by random thermal motion, and Planck’s constant, which relates to the energy of a photon (a particle of light).

    “To try to understand what’s happening in these strange metals, people have applied mathematical approaches similar to those used to understand black holes,” Valles said. “So there’s some very fundamental physics happening in these materials.”

    Of bosons and fermions

    In recent years, Valles and his colleagues have been studying electrical activity in which the charge carriers are not electrons. In 1952, Nobel Laureate Leon Cooper, now a Brown professor emeritus of physics, discovered that in normal superconductors (not the high-temperature kind discovered later), electrons team up to form Cooper pairs, which can glide through an atomic lattice with no resistance. Despite being formed by two electrons, which are fermions, Cooper pairs can act as bosons.

    “Fermion and boson systems usually behave very differently,” Valles said. “Unlike individual fermions, bosons are allowed to share the same quantum state, which means they can move collectively like water molecules in the ripples of a wave.”

    In 2019, Valles and his colleagues showed that Cooper pair bosons can produce metallic behavior, meaning they can conduct electricity with some amount of resistance. That in itself was a surprising finding, the researchers say, because elements of quantum theory suggested that the phenomenon shouldn’t be possible. For this latest research, the team wanted to see if bosonic Cooper-pair metals were also “strange metals”.

    The team used a cuprate material called yttrium barium copper oxide patterned with tiny holes that induce the Cooper-pair metallic state. The team cooled the material down to just above its superconducting temperature to observe changes in its conductance. They found, like fermionic “strange metals”, a Cooper-pair metal conductance that is linear with temperature.

    The researchers say this new discovery will give theorists something new to chew on as they try to understand “strange metal” behavior.

    “It’s been a challenge for theoreticians to come up with an explanation for what we see in ‘strange metals’,” Valles said. “Our work shows that if you’re going to model charge transport in “strange metals”, that model must apply to both fermions and bosons — even though these types of particles follow fundamentally different rules.”

    Ultimately, a theory of “strange metals” could have massive implications. “Strange metal” behavior could hold the key to understanding high-temperature superconductivity, which has vast potential for things like lossless power grids and quantum computers. And because “strange metal” behavior seems to be related to fundamental constants of the universe, understanding their behavior could shed light on basic truths of how the physical world works.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to Brown

    Brown U Robinson Hall

    Brown University (US) is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown University was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its “Open Curriculum” after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College (US), was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College; the Graduate School; Alpert Medical School; the School of Engineering; the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through The Watson Institute for International and Public Affairs at Brown University (US), and the university is academically affiliated with the UChicago Marine Biological Laboratory in Woods Hole, Massachusetts (US) and The Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 26 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 21 MacArthur Genius Fellows, and 37 Olympic medalists.

    The foundation and the charter
    ===
    In 1761, three residents of Newport, Rhode Island, drafted a petition to the colony’s General Assembly:

    “That your Petitioners propose to open a literary institution or School for instructing young Gentlemen in the Languages, Mathematics, Geography & History, & such other branches of Knowledge as shall be desired. That for this End… it will be necessary… to erect a public Building or Buildings for the boarding of the youth & the Residence of the Professors.”

    The three petitioners were Ezra Stiles, pastor of Newport’s Second Congregational Church and future president of Yale University (US); William Ellery, Jr., future signer of the United States Declaration of Independence; and Josias Lyndon, future governor of the colony. Stiles and Ellery later served as co-authors of the college’s charter two years later. The editor of Stiles’s papers observes, “This draft of a petition connects itself with other evidence of Dr. Stiles’s project for a Collegiate Institution in Rhode Island, before the charter of what became Brown University.”

    The Philadelphia Association of Baptist Churches were also interested in establishing a college in Rhode Island—home of the mother church of their denomination. At the time, the Baptists were unrepresented among the colonial colleges; the Congregationalists had Harvard University (US) and Yale, the Presbyterians had the College of New Jersey (later Princeton University (US)), and the Episcopalians had The William & Mary College (US) and King’s College (later Columbia University(US)). Isaac Backus, a historian of the New England Baptists and an inaugural trustee of Brown, wrote of the October 1762 resolution taken at Philadelphia:

    “The Philadelphia Association obtained such an acquaintance with our affairs, as to bring them to an apprehension that it was practicable and expedient to erect a college in the Colony of Rhode-Island, under the chief direction of the Baptists; … Mr. James Manning, who took his first degree in New-Jersey college in September, 1762, was esteemed a suitable leader in this important work.”

    James Manning arrived at Newport in July 1763 and was introduced to Stiles, who agreed to write the charter for the college. Stiles’ first draft was read to the General Assembly in August 1763 and rejected by Baptist members who worried that their denomination would be underrepresented in the College Board of Fellows. A revised charter written by Stiles and Ellery was adopted by the Rhode Island General Assembly on March 3, 1764, in East Greenwich.

    In September 1764, the inaugural meeting of the corporation—the college’s governing body—was held in Newport’s Old Colony House. Governor Stephen Hopkins was chosen chancellor, former and future governor Samuel Ward vice chancellor, John Tillinghast treasurer, and Thomas Eyres secretary. The charter stipulated that the board of trustees should be composed of 22 Baptists, five Quakers, five Episcopalians, and four Congregationalists. Of the 12 Fellows, eight should be Baptists—including the college president—”and the rest indifferently of any or all Denominations.”

    At the time of its creation, Brown’s charter was a uniquely progressive document. Other colleges had curricular strictures against opposing doctrines, while Brown’s charter asserted, “Sectarian differences of opinions, shall not make any Part of the Public and Classical Instruction.” The document additionally “recognized more broadly and fundamentally than any other [university charter] the principle of denominational cooperation.” The oft-repeated statement that Brown’s charter alone prohibited a religious test for College membership is inaccurate; other college charters were similarly liberal in that particular.

    The college was founded as Rhode Island College, at the site of the First Baptist Church in Warren, Rhode Island. James Manning was sworn in as the college’s first president in 1765 and remained in the role until 1791. In 1766, the college authorized Rev. Morgan Edwards to travel to Europe to “solicit Benefactions for this Institution.” During his year-and-a-half stay in the British Isles, the reverend secured funding from benefactors including Thomas Penn and Benjamin Franklin.

    In 1770, the college moved from Warren to Providence. To establish a campus, John and Moses Brown purchased a four-acre lot on the crest of College Hill on behalf of the school. The majority of the property fell within the bounds of the original home lot of Chad Brown, an ancestor of the Browns and one of the original proprietors of Providence Plantations. After the college was relocated to the city, work began on constructing its first building.

    A building committee, organized by the corporation, developed plans for the college’s first purpose-built edifice, finalizing a design on February 9, 1770. The subsequent structure, referred to as “The College Edifice” and later as University Hall, may have been modeled on Nassau Hall, built 14 years prior at the College of New Jersey. President Manning, an active member of the building process, was educated at Princeton and might have suggested that Brown’s first building resemble that of his alma mater.

    The College

    Founded in 1764, the college is Brown’s oldest school. About 7,200 undergraduate students are enrolled in the college, and 81 concentrations are offered. For the graduating class of 2020 the most popular concentrations were Computer Science; Economics; Biology; History; Applied Mathematics; International Relations and Political Science. A quarter of Brown undergraduates complete more than one concentration before graduating. If the existing programs do not align with their intended curricular interests, undergraduates may design and pursue independent concentrations.

    35 percent of undergraduates pursue graduate or professional study immediately, 60 percent within 5 years, and 80 percent within 10 years. For the Class of 2009, 56 percent of all undergraduate alumni have since earned graduate degrees. Among undergraduate alumni who go on to receive graduate degrees, the most common degrees earned are J.D. (16%), M.D. (14%), M.A. (14%), M.Sc. (14%), and Ph.D. (11%). The most common institutions from which undergraduate alumni earn graduate degrees are Brown University, Columbia University, and Harvard University.

    The highest fields of employment for undergraduate alumni ten years after graduation are education and higher education (15%), medicine (9%), business and finance (9%), law (8%), and computing and technology (7%).

    Brown and RISD

    Since its 1893 relocation to College Hill, Rhode Island School of Design (RISD) has bordered Brown to its west. Since 1900, Brown and RISD students have been able to cross-register at the two institutions, with Brown students permitted to take as many as four courses at RISD to count towards their Brown degree. The two institutions partner to provide various student-life services and the two student bodies compose a synergy in the College Hill cultural scene.

    Rankings

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of America’s Top Colleges 2021—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition.[162] The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from The Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest number of Fulbright winners. For the three years prior, the university produced the most Fulbright winners of any university in the nation.

    Research

    Brown is member of The Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

     
  • richardmitnick 5:40 pm on January 7, 2022 Permalink | Reply
    Tags: "Magic-angle" graphene becomes a powerful ferromagnet., "Magic-angle" graphene has caused quite a stir in physics in recent years., "Magnetic surprise revealed in ‘magic-angle’ graphene", , “Magnetism and superconductivity are usually at opposite ends of the spectrum., Brown University (US), Changing the angle of the sheets with respect to each other changes the interactions., , Computer memory, , Electrons begin to interact not only with other electrons within a graphene sheet but also with those in the adjacent sheet., Exciting new possibilities for quantum science research, Magnets are generally destructive to superconductivity., , , , Spin-orbit coupling is a state of electron in which each electron’s spin-its tiny magnetic moment that points either up or down-becomes linked to its orbit around the atomic nucleus., Things get interesting when graphene sheets are stacked., When “magic-angle" graphene” is cooled to near absolute zero it suddenly becomes a superconductor meaning it conducts electricity with zero resistance.   

    From Brown University (US) : “Magnetic surprise revealed in ‘magic-angle’ graphene” 

    From Brown University (US)

    January 6, 2022
    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    Magnets and superconductors don’t normally get along, but a new study shows that “magic-angle” graphene is capable of producing both superconductivity and ferromagnetism, which could be useful in quantum computing.

    1
    When layers of “magic-angle” graphene (bottom) come in contact with layers of certain transitions metals, it induces a phenomenon called spin-orbit coupling in the graphene layers. That phenomenon gives rise to surprising physics, including ferromagnetism. Credit: Li lab/Brown University.

    When two sheets of the carbon nanomaterial graphene are stacked together at a particular angle with respect to each other, it gives rise to some fascinating physics. For instance, when this so-called “magic-angle” graphene is cooled to near absolute zero it suddenly becomes a superconductor meaning it conducts electricity with zero resistance.

    Now, a research team from Brown University has found a surprising new phenomenon that can arise in “magic-angle” graphene. In research published in the journal Science, the team showed that by inducing a phenomenon known as spin-orbit coupling, “magic-angle” graphene becomes a powerful ferromagnet.

    “Magnetism and superconductivity are usually at opposite ends of the spectrum in condensed matter physics, and it’s rare for them to appear in the same material platform,” said Jia Li, an assistant professor of physics at Brown and senior author of the research. “Yet we’ve shown that we can create magnetism in a system that originally hosts superconductivity. This gives us a new way to study the interplay between superconductivity and magnetism, and provides exciting new possibilities for quantum science research.”

    “Magic-angle” graphene has caused quite a stir in physics in recent years. Graphene is a two-dimensional material made of carbon atoms arranged in a honeycomb-like pattern. Single sheets of graphene are interesting on their own — displaying remarkable material strength and extremely efficient electrical conductance. But things get even more interesting when graphene sheets are stacked. Electrons begin to interact not only with other electrons within a graphene sheet but also with those in the adjacent sheet. Changing the angle of the sheets with respect to each other changes those interactions, giving rise to interesting quantum phenomena like superconductivity.

    This new research adds a new wrinkle — spin-orbit coupling — to this already interesting system. Spin-orbit coupling is a state of electron behavior in certain materials in which each electron’s spin — its tiny magnetic moment that points either up or down — becomes linked to its orbit around the atomic nucleus.

    “We know that spin-orbit coupling gives rise to a wide range of interesting quantum phenomena, but it’s not normally present in ‘magic-angle’ graphene,” said Jiang-Xiazi Lin, a postdoctoral researcher at Brown and the study’s lead author. “We wanted to introduce spin-orbit coupling, and then see what effect it had on the system.”

    To do that, Li and his team interfaced “magic-angle” graphene with a block of tungsten diselenide, a material that has strong spin-orbit coupling. Aligning the stack precisely induces spin-orbit coupling in the graphene. From there, the team probed the system with external electrical currents and magnetic fields.

    The experiments showed that an electric current flowing in one direction across the material in the presence of an external magnetic field produces a voltage in the direction perpendicular to the current. That voltage, known as the Hall effect, is the tell-tale signature of an intrinsic magnetic field in the material.

    Much to the research team’s surprise, they showed that the magnetic state could be controlled using an external magnetic field, which is oriented either in the plane of the graphene or out-of-plane. This is in contrast with magnetic materials without spin-orbit coupling, where the intrinsic magnetism can be controlled only when the external magnetic field is aligned along the direction of the magnetism.

    “This observation is an indication that spin-orbit coupling is indeed present and provided the clue for building a theoretical model to understand the influence of the atomic interface,” said Yahui Zhang, a theoretical physicist from Harvard University (US) who worked with the team at Brown to understand the physics associated with the observed magnetism.

    “The unique influence of spin-orbit coupling gives scientists a new experimental knob to turn in the effort to understand the behavior of ‘magic-angle’ graphene,” said Erin Morrissette, a Brown graduate student who performed some of the experimental work. “The findings also have the potential for new device applications.”

    One possible application is in computer memory. The team found that the magnetic properties of “magic-angle” graphene can be controlled with both external magnetic fields and electric fields. That would make this two-dimensional system an ideal candidate for a magnetic memory device with flexible read/write options.

    Another potential application is in quantum computing, the researchers say. An interface between a ferromagnet and a superconductor has been proposed as a potential building block for quantum computers. The problem, however, is that such an interface is difficult to create because magnets are generally destructive to superconductivity. But a material that’s capable of both ferromagnetism and superconductivity could provide a way to create that interface.

    “We are working on using the atomic interface to stabilize superconductivity and ferromagnetism at the same time,” Li said. “The coexistence of these two phenomena is rare in physics, and it will certainly unlock more excitement”

    The research was primarily supported by Brown University. Additional co-authors are Ya-Hui Zhang, Zhi Wang, Song Liu, Daniel Rhodes, Kenji Watanabe, Takashi Taniguchi and James Hone.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to Brown

    Brown U Robinson Hall

    Brown University (US) is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown University was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its “Open Curriculum” after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College (US), was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College; the Graduate School; Alpert Medical School; the School of Engineering; the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through The Watson Institute for International and Public Affairs at Brown University (US), and the university is academically affiliated with the UChicago Marine Biological Laboratory in Woods Hole, Massachusetts (US) and The Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 26 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 21 MacArthur Genius Fellows, and 37 Olympic medalists.

    The foundation and the charter

    In 1761, three residents of Newport, Rhode Island, drafted a petition to the colony’s General Assembly:

    “That your Petitioners propose to open a literary institution or School for instructing young Gentlemen in the Languages, Mathematics, Geography & History, & such other branches of Knowledge as shall be desired. That for this End… it will be necessary… to erect a public Building or Buildings for the boarding of the youth & the Residence of the Professors.”

    The three petitioners were Ezra Stiles, pastor of Newport’s Second Congregational Church and future president of Yale University (US); William Ellery, Jr., future signer of the United States Declaration of Independence; and Josias Lyndon, future governor of the colony. Stiles and Ellery later served as co-authors of the college’s charter two years later. The editor of Stiles’s papers observes, “This draft of a petition connects itself with other evidence of Dr. Stiles’s project for a Collegiate Institution in Rhode Island, before the charter of what became Brown University.”

    The Philadelphia Association of Baptist Churches were also interested in establishing a college in Rhode Island—home of the mother church of their denomination. At the time, the Baptists were unrepresented among the colonial colleges; the Congregationalists had Harvard University (US) and Yale, the Presbyterians had the College of New Jersey (later Princeton University (US)), and the Episcopalians had The William & Mary College (US) and King’s College (later Columbia University(US)). Isaac Backus, a historian of the New England Baptists and an inaugural trustee of Brown, wrote of the October 1762 resolution taken at Philadelphia:

    “The Philadelphia Association obtained such an acquaintance with our affairs, as to bring them to an apprehension that it was practicable and expedient to erect a college in the Colony of Rhode-Island, under the chief direction of the Baptists; … Mr. James Manning, who took his first degree in New-Jersey college in September, 1762, was esteemed a suitable leader in this important work.”

    James Manning arrived at Newport in July 1763 and was introduced to Stiles, who agreed to write the charter for the college. Stiles’ first draft was read to the General Assembly in August 1763 and rejected by Baptist members who worried that their denomination would be underrepresented in the College Board of Fellows. A revised charter written by Stiles and Ellery was adopted by the Rhode Island General Assembly on March 3, 1764, in East Greenwich.

    In September 1764, the inaugural meeting of the corporation—the college’s governing body—was held in Newport’s Old Colony House. Governor Stephen Hopkins was chosen chancellor, former and future governor Samuel Ward vice chancellor, John Tillinghast treasurer, and Thomas Eyres secretary. The charter stipulated that the board of trustees should be composed of 22 Baptists, five Quakers, five Episcopalians, and four Congregationalists. Of the 12 Fellows, eight should be Baptists—including the college president—”and the rest indifferently of any or all Denominations.”

    At the time of its creation, Brown’s charter was a uniquely progressive document. Other colleges had curricular strictures against opposing doctrines, while Brown’s charter asserted, “Sectarian differences of opinions, shall not make any Part of the Public and Classical Instruction.” The document additionally “recognized more broadly and fundamentally than any other [university charter] the principle of denominational cooperation.” The oft-repeated statement that Brown’s charter alone prohibited a religious test for College membership is inaccurate; other college charters were similarly liberal in that particular.

    The college was founded as Rhode Island College, at the site of the First Baptist Church in Warren, Rhode Island. James Manning was sworn in as the college’s first president in 1765 and remained in the role until 1791. In 1766, the college authorized Rev. Morgan Edwards to travel to Europe to “solicit Benefactions for this Institution.” During his year-and-a-half stay in the British Isles, the reverend secured funding from benefactors including Thomas Penn and Benjamin Franklin.

    In 1770, the college moved from Warren to Providence. To establish a campus, John and Moses Brown purchased a four-acre lot on the crest of College Hill on behalf of the school. The majority of the property fell within the bounds of the original home lot of Chad Brown, an ancestor of the Browns and one of the original proprietors of Providence Plantations. After the college was relocated to the city, work began on constructing its first building.

    A building committee, organized by the corporation, developed plans for the college’s first purpose-built edifice, finalizing a design on February 9, 1770. The subsequent structure, referred to as “The College Edifice” and later as University Hall, may have been modeled on Nassau Hall, built 14 years prior at the College of New Jersey. President Manning, an active member of the building process, was educated at Princeton and might have suggested that Brown’s first building resemble that of his alma mater.

    The College

    Founded in 1764, the college is Brown’s oldest school. About 7,200 undergraduate students are enrolled in the college, and 81 concentrations are offered. For the graduating class of 2020 the most popular concentrations were Computer Science; Economics; Biology; History; Applied Mathematics; International Relations and Political Science. A quarter of Brown undergraduates complete more than one concentration before graduating. If the existing programs do not align with their intended curricular interests, undergraduates may design and pursue independent concentrations.

    35 percent of undergraduates pursue graduate or professional study immediately, 60 percent within 5 years, and 80 percent within 10 years. For the Class of 2009, 56 percent of all undergraduate alumni have since earned graduate degrees. Among undergraduate alumni who go on to receive graduate degrees, the most common degrees earned are J.D. (16%), M.D. (14%), M.A. (14%), M.Sc. (14%), and Ph.D. (11%). The most common institutions from which undergraduate alumni earn graduate degrees are Brown University, Columbia University, and Harvard University.

    The highest fields of employment for undergraduate alumni ten years after graduation are education and higher education (15%), medicine (9%), business and finance (9%), law (8%), and computing and technology (7%).

    Brown and RISD

    Since its 1893 relocation to College Hill, Rhode Island School of Design (RISD) has bordered Brown to its west. Since 1900, Brown and RISD students have been able to cross-register at the two institutions, with Brown students permitted to take as many as four courses at RISD to count towards their Brown degree. The two institutions partner to provide various student-life services and the two student bodies compose a synergy in the College Hill cultural scene.

    Rankings

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of America’s Top Colleges 2021—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition.[162] The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from The Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest number of Fulbright winners. For the three years prior, the university produced the most Fulbright winners of any university in the nation.

    Research

    Brown is member of The Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

     
  • richardmitnick 12:52 pm on December 27, 2021 Permalink | Reply
    Tags: "Vast patches of glassy rock in Chilean desert likely created by ancient exploding comet", , Brown University (US), , , , Samples of the desert glass contain tiny fragments with minerals often found in rocks of extraterrestrial origin., Some researchers have posited that the glass resulted from ancient grass fires as the region wasn’t always desert., The amount of glass present along with several key physical characteristics make simple fires an impossible formation mechanism., The comet exploded around 12000 years ago., The glasses are concentrated in patches across the Atacama Desert east of Pampa del Tamarugal nestled between the Andes Mountains to the east and the Chilean Coastal Range to the west., This is the first time there is clear evidence of glasses on Earth being created by the thermal radiation and winds from a fireball exploding just above the surface.   

    From Brown University (US) : “Vast patches of glassy rock in Chilean desert likely created by ancient exploding comet” 

    From Brown University (US)

    November 2, 2021 [Just now in social media.]

    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    New research finds that the dark silicate glass strewn across a vast swath of the Atacama Desert was created by an exploding comet around 12,000 years ago. Credit: P.H. Schultz, Brown University.

    Around 12,000 years ago, something scorched a vast swath of the Atacama Desert in Chile with heat so intense that it turned the sandy soil into widespread slabs of silicate glass. Now, a research team studying the distribution and composition of those glasses has come to a conclusion about what caused the inferno.

    In a study published in the journal Geology, researchers show that samples of the desert glass contain tiny fragments with minerals often found in rocks of extraterrestrial origin. Those minerals closely match the composition of material returned to Earth by NASA’s Stardust mission, which sampled the particles from a comet called Wild 2. The team concludes that those mineral assemblages are likely the remains of an extraterrestrial object — most likely a comet with a composition similar to Wild 2 — that streamed down after the explosion that melted the sandy surface below.

    “This is the first time we have clear evidence of glasses on Earth that were created by the thermal radiation and winds from a fireball exploding just above the surface,” said Pete Schultz, a professor emeritus in Brown University’s Department of Earth, Environmental and Planetary Sciences. “To have such a dramatic effect on such a large area, this was a truly massive explosion. Lots of us have seen bolide fireballs streaking across the sky, but those are tiny blips compared to this.”

    3
    Image of glass deposits. The glass deposits stretch along a 75-kilometer corridor in northern Chile.

    The glasses are concentrated in patches across the Atacama Desert east of Pampa del Tamarugal, a plateau in northern Chile nestled between the Andes Mountains to the east and the Chilean Coastal Range to the west. Fields of dark green or black glass occur within a corridor stretching about 75 kilometers. There’s no evidence that the glasses could have been created by volcanic activity, Schultz says, so their origin has been a mystery.

    Some researchers have posited that the glass resulted from ancient grass fires as the region wasn’t always desert. During the Pleistocene epoch, there were oases with trees and grassy wetlands created by rivers extending from mountains to the east, and it’s been suggested that widespread fires may have burned hot enough to melt the sandy soil into large glassy slabs.

    But the amount of glass present along with several key physical characteristics make simple fires an impossible formation mechanism, the new research found. The glasses show evidence of having been twisted, folded, rolled and even thrown while still in molten form. That’s consistent with a large incoming meteor and airburst explosion, which would have been accompanied by tornado-force winds. The mineralogy of the glass casts further serious doubt on the grassfire idea, Schultz says. Along with researchers from the Fernbank Science Center in Georgia, Chile’s The Saint Thomas Aquinas University[Universidad Santo Tomás](CO) and the Chilean Geology and Mining Service, Schultz and colleagues performed a detailed chemical analysis of dozens of samples taken from glass deposits across the region.

    The analysis found minerals called zircons that had thermally decomposed to form baddeleyite. That mineral transition typically happens in temperatures in excess of 3,000 degrees Fahrenheit — far hotter than what could be generated by grass fires, Schultz says.

    3
    Analysis of the samples revealed a mineralogy consistent with a cometary origin.

    The analysis also turned up assemblages of exotic minerals only found in meteorites and other extraterrestrial rocks, the researchers say. Specific minerals like cubanite, troilite and calcium-aluminum-rich inclusions matched mineral signatures from comet samples retrieved from NASA’s Stardust mission.

    “Those minerals are what tell us that this object has all the markings of a comet,” said Scott Harris, a planetary geologist at the Fernbank Science Center and study co-author. “To have the same mineralogy we saw in the Stardust samples entrained in these glasses is really powerful evidence that what we’re seeing is the result of a cometary airburst.”

    More work needs to be done to establish the exact ages of the glass, which would determine exactly when the event took place, Schultz says. But the tentative dating puts the impact right around time that large mammals disappeared from the region.

    “It’s too soon to say if there was a causal connection or not, but what we can say is that this event did happen around the same time as when we think the megafauna disappeared, which is intriguing,” Schultz said. “There’s also a chance that this was actually witnessed by early inhabitants, who had just arrived in the region. It would have been quite a show.”

    Schultz and his team hope that further research may help to constrain the timing and shed light on the size of the impactor. For now, Schultz hopes this study may help researchers identify similar blast sites elsewhere and reveal the potential risk posed by such events.

    “There may be lots of these blast scars out there, but until now we haven’t had enough evidence to make us believe they were truly related to airburst events,” Schultz said. “I think this site provides a template to help refine our impact models and will help to identify similar sites elsewhere.”

    Other authors of the study were Sebastian Perroud, Nicolas Blanco and Andrew Tomlinson.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Welcome to Brown

    Brown U Robinson Hall

    Brown University (US) is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown University was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its “Open Curriculum” after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College (US), was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College; the Graduate School; Alpert Medical School; the School of Engineering; the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through The Watson Institute for International and Public Affairs at Brown University (US), and the university is academically affiliated with the UChicago Marine Biological Laboratory in Woods Hole, Massachusetts (US) and The Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 26 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 21 MacArthur Genius Fellows, and 37 Olympic medalists.

    The foundation and the charter
    ===
    In 1761, three residents of Newport, Rhode Island, drafted a petition to the colony’s General Assembly:

    “That your Petitioners propose to open a literary institution or School for instructing young Gentlemen in the Languages, Mathematics, Geography & History, & such other branches of Knowledge as shall be desired. That for this End… it will be necessary… to erect a public Building or Buildings for the boarding of the youth & the Residence of the Professors.”

    The three petitioners were Ezra Stiles, pastor of Newport’s Second Congregational Church and future president of Yale University (US); William Ellery, Jr., future signer of the United States Declaration of Independence; and Josias Lyndon, future governor of the colony. Stiles and Ellery later served as co-authors of the college’s charter two years later. The editor of Stiles’s papers observes, “This draft of a petition connects itself with other evidence of Dr. Stiles’s project for a Collegiate Institution in Rhode Island, before the charter of what became Brown University.”

    The Philadelphia Association of Baptist Churches were also interested in establishing a college in Rhode Island—home of the mother church of their denomination. At the time, the Baptists were unrepresented among the colonial colleges; the Congregationalists had Harvard University (US) and Yale, the Presbyterians had the College of New Jersey (later Princeton University (US)), and the Episcopalians had The William & Mary College (US) and King’s College (later Columbia University(US)). Isaac Backus, a historian of the New England Baptists and an inaugural trustee of Brown, wrote of the October 1762 resolution taken at Philadelphia:

    “The Philadelphia Association obtained such an acquaintance with our affairs, as to bring them to an apprehension that it was practicable and expedient to erect a college in the Colony of Rhode-Island, under the chief direction of the Baptists; … Mr. James Manning, who took his first degree in New-Jersey college in September, 1762, was esteemed a suitable leader in this important work.”

    James Manning arrived at Newport in July 1763 and was introduced to Stiles, who agreed to write the charter for the college. Stiles’ first draft was read to the General Assembly in August 1763 and rejected by Baptist members who worried that their denomination would be underrepresented in the College Board of Fellows. A revised charter written by Stiles and Ellery was adopted by the Rhode Island General Assembly on March 3, 1764, in East Greenwich.

    In September 1764, the inaugural meeting of the corporation—the college’s governing body—was held in Newport’s Old Colony House. Governor Stephen Hopkins was chosen chancellor, former and future governor Samuel Ward vice chancellor, John Tillinghast treasurer, and Thomas Eyres secretary. The charter stipulated that the board of trustees should be composed of 22 Baptists, five Quakers, five Episcopalians, and four Congregationalists. Of the 12 Fellows, eight should be Baptists—including the college president—”and the rest indifferently of any or all Denominations.”

    At the time of its creation, Brown’s charter was a uniquely progressive document. Other colleges had curricular strictures against opposing doctrines, while Brown’s charter asserted, “Sectarian differences of opinions, shall not make any Part of the Public and Classical Instruction.” The document additionally “recognized more broadly and fundamentally than any other [university charter] the principle of denominational cooperation.” The oft-repeated statement that Brown’s charter alone prohibited a religious test for College membership is inaccurate; other college charters were similarly liberal in that particular.

    The college was founded as Rhode Island College, at the site of the First Baptist Church in Warren, Rhode Island. James Manning was sworn in as the college’s first president in 1765 and remained in the role until 1791. In 1766, the college authorized Rev. Morgan Edwards to travel to Europe to “solicit Benefactions for this Institution.” During his year-and-a-half stay in the British Isles, the reverend secured funding from benefactors including Thomas Penn and Benjamin Franklin.

    In 1770, the college moved from Warren to Providence. To establish a campus, John and Moses Brown purchased a four-acre lot on the crest of College Hill on behalf of the school. The majority of the property fell within the bounds of the original home lot of Chad Brown, an ancestor of the Browns and one of the original proprietors of Providence Plantations. After the college was relocated to the city, work began on constructing its first building.

    A building committee, organized by the corporation, developed plans for the college’s first purpose-built edifice, finalizing a design on February 9, 1770. The subsequent structure, referred to as “The College Edifice” and later as University Hall, may have been modeled on Nassau Hall, built 14 years prior at the College of New Jersey. President Manning, an active member of the building process, was educated at Princeton and might have suggested that Brown’s first building resemble that of his alma mater.

    The College

    Founded in 1764, the college is Brown’s oldest school. About 7,200 undergraduate students are enrolled in the college, and 81 concentrations are offered. For the graduating class of 2020 the most popular concentrations were Computer Science; Economics; Biology; History; Applied Mathematics; International Relations and Political Science. A quarter of Brown undergraduates complete more than one concentration before graduating. If the existing programs do not align with their intended curricular interests, undergraduates may design and pursue independent concentrations.

    35 percent of undergraduates pursue graduate or professional study immediately, 60 percent within 5 years, and 80 percent within 10 years. For the Class of 2009, 56 percent of all undergraduate alumni have since earned graduate degrees. Among undergraduate alumni who go on to receive graduate degrees, the most common degrees earned are J.D. (16%), M.D. (14%), M.A. (14%), M.Sc. (14%), and Ph.D. (11%). The most common institutions from which undergraduate alumni earn graduate degrees are Brown University, Columbia University, and Harvard University.

    The highest fields of employment for undergraduate alumni ten years after graduation are education and higher education (15%), medicine (9%), business and finance (9%), law (8%), and computing and technology (7%).

    Brown and RISD

    Since its 1893 relocation to College Hill, Rhode Island School of Design (RISD) has bordered Brown to its west. Since 1900, Brown and RISD students have been able to cross-register at the two institutions, with Brown students permitted to take as many as four courses at RISD to count towards their Brown degree. The two institutions partner to provide various student-life services and the two student bodies compose a synergy in the College Hill cultural scene.

    Rankings

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of America’s Top Colleges 2021—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition.[162] The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from The Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest number of Fulbright winners. For the three years prior, the university produced the most Fulbright winners of any university in the nation.

    Research

    Brown is member of The Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

     
  • richardmitnick 8:09 am on November 18, 2021 Permalink | Reply
    Tags: "An ancient exploding comet may explain why glass litters part of Chile", , , Brown University (US), , , Planetary geology   

    From Brown University (US) via Science News (US) : “An ancient exploding comet may explain why glass litters part of Chile” 

    From Brown University (US)

    via

    Science News (US)

    November 17, 2021
    Freda Kreier

    An airburst over the Atacama Desert 12,000 years ago melted the ground into glass, scientists say.

    1
    A 75-kilometer-long stretch of the Atacama Desert is home to twisted chunks of glass (dark chunks in this image). The glass formed when a comet, or its remnants, exploded over the area 12,000 years ago, researchers say. Credit: P.H. Schultz/Brown University.

    Scattered across a swath of the Atacama Desert in Chile lie twisted chunks of black and green glass. How the glass ended up there, sprinkled along a 75-kilometer-long corridor, has been a mystery.

    Now, analyses of space dust in the glass show that the glass probably formed when a comet, or its remnants, exploded over the desert 12,000 years ago, researchers report November 2 in Geology.

    This corridor is the best evidence yet of a comet impact site on Earth, says Peter Schultz, a planetary geologist at Brown University (US) in Providence, R.I.

    There are only about 190 known impact craters on Earth (SN: 12/18/18). Falling space rocks carved out these sites, but none are known to have been created by a comet. That’s because comets, which are made of mostly ice and some rock, tend to explode before reaching the ground, a fate they share with some small asteroids. These fiery events — known as airbursts — are dramatic, generating massive amounts of heat and strong winds. But the effects are temporary and often fail to leave lasting imprints, like craters, behind.

    That’s especially true in wet environments. In 1908, an airburst from an asteroid or comet over a remote part of Russia flattened trees and generated a shock wave that knocked people off their feet hundreds of kilometers away. The trees have since grown back over the site of what’s now known as the Tunguska blast, leaving just a marsh (SN: 6/5/08). “If it hadn’t been observed, no one would know it happened,” says Mark Boslough, a physicist at The University of New Mexico (US) in Albuquerque who wasn’t involved in the new research.

    The Atacama, the world’s driest desert, is better suited to preserving impact sites. And it’s full of sand — the raw material for making glass, which forms when sand is heated to high temperatures. Heat from volcanic activity is responsible for almost all of the naturally derived glass on Earth.

    The desert’s glass corridor, however, is kilometers away from the closest volcano, suggesting the glass formed in a different type of heating event, such as an airburst. But radiocarbon dating of ancient plants in the soil around the glass seemed to indicate that the pieces didn’t all form at the same time. Because airbursts rarely occur in the same place twice, the evidence led some researchers to suggest that the glass formed during several massive grass fires.

    That idea, Schultz says, “seemed really weird to us because there just wasn’t enough grass for fires,” even long ago when the area probably had more greenery than it does today. After examining some of the glass, he and colleagues determined that it had formed at temperatures exceeding 1700° Celsius — much hotter than grass fires.

    What’s more, the team discovered embedded within the glass compounds found in comets sampled during NASA’s Stardust mission but almost never in asteroids (SN: 1/7/04). The only way for this space dust to have made its way into the glass is if a very old chunk of space debris, such as a comet, exploded at the moment that the glass formed, the researchers say.

    2
    Strong winds from an ancient comet’s explosion folded glass as it formed in what’s now the Atacama Desert, a study finds. Folds in the glass are visible in a microscope image (left) of a section from a larger chunk of glass (right). The yellow dot marks where the section was taken. Credit: Scott Harris/Fernbank Science Center (US).

    “It’s pretty clear that this is an impact,” Boslough says. “And in this case, there’s no evidence for a crater, so this event was a pure airburst.”

    An airburst would also help explain why the glass appears twisted. “It was clear the glass had been thrown around and rolled. It was basically kneaded like bread,” Schultz says. Grass fires may melt the ground, but they rarely fling it around. Like Tunguska, the airburst probably generated strong winds that flung the glass as it formed, creating the folded look.

    The violence of the impact would have scattered glass far across the desert and onto different layers of sediment. Because those layers formed at different times, that may have created the illusion that the glass was created during multiple events. Looking at the dating of plants that came in direct contact with the glass allowed the researchers to pin down the date of the probable comet strike to about 12,000 years ago.

    That timing places the event about 800 years after a mysterious period of rapid cooling known as the Younger Dryas, which coincided with the extinction of many large animals. Some scientists have suggested that a comet exploding over the Northern Hemisphere set off a series of events that led to the frigid conditions, though the idea is controversial (SN: 6/26/18).

    The timing of the Atacama comet strike shows that it wasn’t related to the Younger Dryas event, Schultz says, but the finding does lay the groundwork for identifying other potential comet sites on Earth.

    Even without a link to the Younger Dryas, the Atacama impact would have left a strong impression on anyone who saw it. Archaeological evidence suggests that people lived in the area at the time and thus may have witnessed the airburst (SN: 11/30/15). “It would have seemed like the entire horizon was on fire,” Schultz says. “If you weren’t religious before, you would be after.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Welcome to Brown

    Brown U Robinson Hall
    Brown University is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its Open Curriculum after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College, was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College, the Graduate School, Alpert Medical School, the School of Engineering, the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through the Watson Institute for International and Public Affairs, and the university is academically affiliated with the Marine Biological Laboratory (US) and the Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 32 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 20 MacArthur Genius Fellows, and 37 Olympic medalists.

    Brown is member of the Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of “America’s Top Colleges 2021“—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition. The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton University (US)) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from the Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest amount of Fulbright winners. For the three years prior, the university pr

     
  • richardmitnick 7:48 pm on October 26, 2021 Permalink | Reply
    Tags: "Researchers show new strategy for detecting non-conformist particles called anyons", Anyons are of interest because they don’t follow the same rules as particles in the everyday three-dimensional world., Anyons-which emerge only in systems that are confined to two dimensions-don’t follow either rule., Bosons follow what’s known as Bose-Einstein statistics while fermions follow Fermi-Dirac statistics., Brown University (US), But using anyons for computing requires first being able to identify these particles by probing their quantum statistics., Last year researchers did that probe for the first time using a technique known as charge interferometry., The team describes a means of probing anyons by measuring subtle properties of the way in which they conduct heat., Topological quantum computing, When one anyon orbits another its wave function changes by some fraction of an integer. And another orbit does not necessarily restore the original value of the wave function.   

    From Brown University (US) : “Researchers show new strategy for detecting non-conformist particles called anyons” 

    From Brown University (US)

    October 26, 2021
    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    Credit: Brown University.

    By observing how strange particles called anyons dissipate heat, researchers have shown that they can probe the properties of these particles in systems that could be relevant for topological quantum computing.

    A team of Brown University researchers has shown a new method of probing the properties of anyons, strange quasiparticles that could be useful in future quantum computers.

    In research published in the journal Physical Review Letters, the team describes a means of probing anyons by measuring subtle properties of the way in which they conduct heat. Whereas other methods probe these particles using electrical charge, this new method enables researchers to probe anyons even in non-conducting materials. That’s critical, the researchers say, because non-conducting systems have far less stringent temperature requirements, making them a more practical option for quantum computing.

    “We have beautiful ways of probing anyons using charge, but the question has been how do you detect them in the insulating systems that would be useful in what’s known as topological quantum computing,” said Dima Feldman, a physics professor at Brown and study co-author. “We show that it can be done using heat conductance. Essentially, this is a universal test for anyons that works in any state of matter.”

    Anyons are of interest because they don’t follow the same rules as particles in the everyday three-dimensional world. In three dimensions, there are only two broad kinds of particles: bosons and fermions. Bosons follow what’s known as Bose-Einstein statistics while fermions follow Fermi-Dirac statistics. Generally speaking, those different sets of statistical rules mean that if one boson orbits around another in a quantum system, the particle’s wave function — the equation that fully describes its quantum state — does not change. On the other hand, if a fermion orbits around another fermion, the phase value of its wave function flips from a positive integer to a negative integer. If it orbits again, the wave function returns to its original state.

    Anyons-which emerge only in systems that are confined to two dimensions-don’t follow either rule. When one anyon orbits another its wave function changes by some fraction of an integer. And another orbit does not necessarily restore the original value of the wave function. Instead, it has a new value — almost as if the particle maintains a “memory” of its interactions with the other particle even though it ended up back where it started.

    That memory of past interactions can be used to encode information in a robust way, which is why the particles are interesting tools for quantum computing. Quantum computers promise to perform certain types of calculations that are virtually impossible for today’s computers. A quantum computer using anyons — known as a topological quantum computer — has the potential to operate without elaborate error correction, which is a major stumbling block in the quest for usable quantum computers.

    But using anyons for computing requires first being able to identify these particles by probing their quantum statistics. Last year researchers did that probe for the first time using a technique known as charge interferometry. Essentially, anyons are spun around each other, causing their wave functions to interfere with each other occasionally. The pattern of interference reveals the particles’ quantum statistics. That technique of probing anyons using charge works beautifully in systems that conduct electricity, the researchers say, but it can’t be used to probe anyons in non-conducting systems. And non-conducting systems have the potential to be useful at higher temperatures than conducting systems, which need to be near absolute zero. That makes them a more practical option of topological quantum computing.

    For this new research, Feldman, who in 2017 was part of a team that measured the heat conductance of anyons for the first time, collaborated with Brown graduate student Zezhu Wei and Vesna Mitrovic, a Brown physics professor and experimentalist. Wei, Feldman and Mitrovic showed that comparing properties of heat conductance in two-dimensional solids etched in very specific geometries could reveal the statistics of the anyons in those systems.

    “Any difference in the heat conductance in the two geometries would be smoking gun evidence of fractional statistics,” Mitrovic said. “What this study does is show exactly how people should set up experiments in their labs to test for these strange statistics.”

    Ultimately, the researchers hope the study is a step toward understanding whether the strange behavior of anyons can indeed be harnessed for topological quantum computing.

    See the full article here .

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    Please help promote STEM in your local schools.

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    Welcome to Brown

    Brown U Robinson Hall

    Brown University is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

    At its foundation, Brown was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its Open Curriculum after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College, was fully merged into the university.

    Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.

    The university comprises the College, the Graduate School, Alpert Medical School, the School of Engineering, the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through the Watson Institute for International and Public Affairs, and the university is academically affiliated with the Marine Biological Laboratory (US) and the Rhode Island School of Design (US). In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.

    Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.

    As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 32 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 20 MacArthur Genius Fellows, and 37 Olympic medalists.

    Brown is member of the Association of American Universities (US) since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation (US).

    Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.

    The Forbes Magazine annual ranking of “America’s Top Colleges 2021“—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.

    U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition. The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.

    Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.

    For 2020, U.S. News & World Report ranks Brown 102nd globally.

    In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.

    LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology (US) and Princeton University (US)) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.

    In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.

    According to 2020 data from the Department of Education (US), the median starting salary of Brown computer science graduates was the highest in the United States.

    In 2020, Brown produced the second-highest amount of Fulbright winners. For the three years prior, the university produced the most Fulbright winners in the nation.

     
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