2,177 research outputs found
Absolute low-pressure calibration system
McLeod gage is used as the primary reference standard in a system used for absolute calibration of vacuum gages in the very low pressure range. The system involves steady-state flow of a gas through a cascade of differentially pumped chambers or stages connected by precisely defined orifices
Chiral Splitting and Einstein--Yang--Mills Tree Amplitudes in 4d
We present a world-sheet formula for all tree level scattering amplitudes, in
all trace sectors, of four dimensional supersymmetric
Einstein-Yang-Mills theory, based on the refined scattering equations. This
generalizes previously known formulas for all-trace purely bosonic, or
supersymmetric single-trace amplitudes. We find this formula by applying a new
chiral splitting formula for all CHY Pfaffians in 4d, into two determinants, of
positive and negative helicity respectively. The splitting of CHY Pfaffians is
shown to be a special case of the splitting of valued fermion
correlators on the sphere, which does not require the scattering equations to
hold, and is a consequence of the isomorphism between the tangent bundle of Minkowski space and the
left- and right-handed spin bundles. We present and prove this general
splitting formula.Comment: 21 page
Multiparty Quantum Coin Flipping
We investigate coin-flipping protocols for multiple parties in a quantum
broadcast setting:
(1) We propose and motivate a definition for quantum broadcast. Our model of
quantum broadcast channel is new.
(2) We discovered that quantum broadcast is essentially a combination of
pairwise quantum channels and a classical broadcast channel. This is a somewhat
surprising conclusion, but helps us in both our lower and upper bounds.
(3) We provide tight upper and lower bounds on the optimal bias epsilon of a
coin which can be flipped by k parties of which exactly g parties are honest:
for any 1 <= g <= k, epsilon = 1/2 - Theta(g/k).
Thus, as long as a constant fraction of the players are honest, they can
prevent the coin from being fixed with at least a constant probability. This
result stands in sharp contrast with the classical setting, where no
non-trivial coin-flipping is possible when g <= k/2.Comment: v2: bounds now tight via new protocol; to appear at IEEE Conference
on Computational Complexity 200
Quantum Property Testing
A language L has a property tester if there exists a probabilistic algorithm
that given an input x only asks a small number of bits of x and distinguishes
the cases as to whether x is in L and x has large Hamming distance from all y
in L. We define a similar notion of quantum property testing and show that
there exist languages with quantum property testers but no good classical
testers. We also show there exist languages which require a large number of
queries even for quantumly testing
Research and development program on the use of counting techniques
Reducing noise in multiplier of quadrupole mass spectrometer when operating in ion counting mod
Design, fabrication, assembly and delivery of a laboratory prototype of a residual gas analyzer
The design, development, and testing of a wide mass range residual gas analyzer which will be one component of an integrated real time contamination monitor system are described. The instrument has been developed and tested to the laboratory prototype phase, demonstrating the performance that can be expected from a flight instrument of similar design. The instrument's analyzer is of the quadrupole type and a cold cathode ion source is employed as the ionizer. The associated electronics supply all necessary operating and mass sweep voltages for the ionizer, analyzer and electron multiplier ion detector. The instrument features a very fast linear electrometer with automatic range changing. The full mass range of 2 to 300 amu is automatically and repetitively scanned every sixty seconds and suitable telemetry outputs are provided for intensity and mass identification as well as a digital identification of the electrometer range
An Examination Of The Multilevel Determinants Of Homelessness
Objectives: This project aimed to explore factors contributing to homelessness within Fairfield County, Connecticut in order to understand how to develop prevention services that best match the population’s needs.
Methods: This project draws on data collected from a qualitative study done by Supportive Housing Works, where researchers conducted 2 focus groups and 44 semi-structured interviews with individuals experiencing homelessness or housing instability in Bridgeport, CT. Participants were recruited by posting flyers, as well as referrals from programs such as Prospect House, and other Opening Doors Fairfield County (ODFC) partner agencies. Eligible participants had to be registered with the Homeless Management Integration System as either an “individual” or “family” 18 years and older, and all respondents were compensated $10. Analysis and thematic coding of the transcripts was conducted using Dedoose.
Results: While the age at which participants first experienced homelessness varied, they identified several common factors that contributed to first-time, chronic, and episodic homelessness throughout their life courses. These ranged from adverse childhood experiences, derailing events such as incarceration and eviction, lack of social relationships and support, inadequate mental healthcare, barriers to employment, and navigating the system of “broken promises”. These factors were often related to one another both directly and indirectly, and accumulated over time, creating significant barriers to stable housing.
Discussion: Efforts to improve homelessness prevention programs must address the lack of affordable housing, improve reentry programs for those leaving incarceration, improve mental healthcare, and increase employment opportunities as well as social support. Programs that serve this population must ensure that clients feel empowered and respected, and that the process of applying for housing assistance, unemployment and disability benefits, is transparent and not too onerous. Given participants’ lack of social support to help buffer against derailing events, there should be a greater focus on finding ways to integrate those at-risk for homelessness into their community through meaningful employment opportunities and fostering supportive relationships
New Ambitwistor String Theories
We describe new ambitwistor string theories that give rise to the recent
amplitude formulae for Einstein-Yang-Mills, (Dirac)-Born-Infeld, Galileons and
others introduced by Cachazo, He and Yuan. In the case of the
Einstein-Yang-Mills amplitudes, an important role is played by a novel
worldsheet conformal field theory that provides the appropriate colour factors
precisely without the spurious multitrace terms of earlier models that had to
be ignored by hand. This is needed to obtain the correct multitrace terms that
arise when Yang-Mills is coupled to gravity.Comment: 34 pages, 2 figures, 5 tables. v2: minor changes, published versio
Indexicais e operadores-monstros no português brasileiro
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em LinguísticaEsta dissertação tem por objetivo abordar as principais ideias sobre a indexicalidade e sobre as questões que ainda são motivo de desacordo em relação ao fenômeno. Para dar conta disso, no Capítulo 1 apresentamos a principal teoria semântica para os indexicais, proposta por Kaplan (1989). Essa teoria tem as seguintes linhas gerais: define os indexicais como termos diretamente referenciais e como designadores rígidos; classifica-os em indexicais puros e demonstrativos; caracteriza-os como termos que são sempre dependentes do contexto de proferimento hic et nunc; e trata o significado desses itens como sendo composto por duas funções, o caráter e o conteúdo. Se, por um lado, essa distinção representa um dos méritos da teoria de Kaplan (1989), por outro lado, a teoria dos indexicais proposta pelo autor é muito criticada por causa da proibição contra operadores-monstros e indexicais monstruosos em língua natural. O segundo capítulo apresenta as refutações de Schlenker (1999, 2003, 2010) em relação à Kaplan (1989), principalmente no que diz respeito à proibição da existência de operadores-monstros e indexicais monstruosos. Apoiado em línguas como amárico e o inglês, Schlenker argumenta que o operador de atitude pode ser um operador-monstro em alguns casos. Na verdade, sempre que houver uma indexical com o comportamento monstruoso na sentença, há um operador de atitude atuando. No entanto, também podem ser encontrados indexicais kaplanianos no escopo do operador de atitude. Apresentamos, também, os critérios estabelecidos pela teoria de Schlenker (1999, 2003, 2010) para encontrar operadores-monstros e indexicais monstruosos nas línguas naturais. Com base neles, analisamos alguns indexicais do domínio temporal do PB; as expressões 'em dois dias' e 'dois dias atrás' se adequaram aos critérios de Schlenker. Assim sendo, essas expressões podem ser avaliadas num contexto diferente do contexto de proferimento (c*). Além disso, foram feitas algumas especulações em relação ao indexical 'aqui', que pode ser considerado um indexical monstruoso se for aceita a ideia de que apesar do termo não estar expresso em algumas sentenças, ele tem papel fundamental na interpretação dessas sentenças. No terceiro capítulo, lidamos com os problemas decorrentes da relação entre o discurso metaficcional (sentenças sobre ficção) e as expressões indexicais. Isso foi feito pelas suspeitas de que a interpretação de certas sentenças metaficcionais pode exigir mudanças nos contextos de avaliação dos indexicais. Essa suspeita foi fundamentada pela abordagem de Predelli (2008), em que é proposto um operador-monstro-modal. Verificamos que, de fato, afirmar a existência de indexicais monstruosos no discurso metaficcional e utilizar uma teoria baseada em operadores-monstros explica os casos em tela de maneira adequada e econômica. Para dar conta da sentença metaficcional 'Eu acho que eu poderia morar mais perto dela', para qual o operador-monstro-modal de Predelli (2008) é insuficiente, propomos, no Capítulo 3, o operador metaficcional (BASSO; TEIXEIRA, 2011) (ampliação do operador de Predelli). Esse operador tem por incumbência modelar que o agente do contexto do segundo 'eu' e o indivíduo apontado, representado pelo indexical 'dela', devem ser fixados no contexto ficcional. Por fim, verificamos que para dar conta dos indexicais monstruosos encontrados no PB, analisados nos Capítulos 2 e 3, é necessário que as concepções de operadores-monstros e de indexicais monstruosos de Kaplan (1989) sejam assumidas, visto que as de Schlenker (1999, 2003, 2010) são muito estreitas e não permitem que os indexicais monstruosos do discurso metaficcional sejam avaliados de maneira satisfatória.This dissertation aims to investigate indexicals, highlighting the main related issues that have causing divergences in the literature. The first chapter presents the main semantics approach for indexicals, proposed by Kaplan (1989). Basically, this theory exploits indexicals according to the following lines: it defines them as directly referential terms and rigid designators; it classifies them as pure and demonstratives; it characterizes them as terms that are always dependent on the utterance context hic et nunc; and, finally, it deals with their meaning as being composed by two functions: the character and the content. If on one hand this distinction represents on of the most important merit of the Kaplan#s theory, on the other hand, it is criticized by prohibiting operators and indexicals monsters in natural language. The second chapter presents the refutations of Schlenker (1999, 2003, 2010) to Kaplan, with respect to the prohibition against operators and indexicals monsters. Supported by languages such as Amharic and English, Schlenker has argued that the attitude operator can be a monster operator, in some cases. In fact, whenever there is an indexical with monstrous behavior in the sentence, there is an attitude operator acting. However, it may also exist kaplanian indexicals under the scope of the attitude operator. We also present the criteria established by Schlenker to find operators and indexicals monsters in natural languages. Based on that, we have analyzed some indexicals in the Brasilian Portuguese temporal domain, which have shown that expressions like #em dois dias# and #dois dias atr´as# are monsters indexicals. Hence, they can be evaluated in a different context than the utterance context (c*). Finally, we also have speculated the indexical #aqui#, which can be considered a monster indexical, since we accept that, although the word #aqui# is not expressed in some sentences, it plays a fundamental role in their interpretation. In the third chapter, we deal with the problems arising from the relationship between the metafictional discourse (sentences about fiction) and the indexicals expressions. The interpretation of some sentences related with the fiction, may require shiftings in the contexts. It has been supported by the Predelli#s approach, which proposes a monstermodal-operator for these cases. In fact, we verify that to claim the existence of the indexicals monsters in metafictional discourse and to use the operators monsters theory to describe the cases in question is a elegant and a economic explanation. In addition, to take into account sentences like #Eu acho que eu poderia morar mais perto dela#, in which the operator-monster-modal of Predelli (2008) is insufficient, we propose the metafictional operator (BASSO; TEIXEIRA, 2011) (extending operator Predelli (2008)). This operator focus on modeling that the agent of the context of the second #eu# and the appointed person, represented by the indexical #ela#, both must be set in the fictional context, unlike the first #eu#, that has its value set in the context of utterance. Finally, it worth to notice that explaining the indexicals monsters found in Brasilian Portuguese (Chapters 2 and 3) requires to assume as correct the Kaplan#s conceptions about operators and indexicals monsters, since the conceptions of Schlenker are narrow and do not allow to account the metafictional indexicals monsters
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