5,784 research outputs found
Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the Surface of a Superconductor
We study macroscopic quantum tunneling of the magnetic moment in a
single-domain particle placed above the surface of a superconductor. Such a
setup allows one to manipulate the height of the energy barrier, preserving the
degeneracy of the ground state. The tunneling amplitude and the effect of the
dissipation in the superconductor are computed.Comment: RevTeX, 4 pages, 1 figure. Submitted to Phys. Rev. Let
General Neutralino NLSPs at the Early LHC
Gauge mediated supersymmetry breaking (GMSB) is a theoretically
well-motivated framework with rich and varied collider phenomenology. In this
paper, we study the Tevatron limits and LHC discovery potential for a wide
class of GMSB scenarios in which the next-to-lightest superpartner (NLSP) is a
promptly-decaying neutralino. These scenarios give rise to signatures involving
hard photons, 's, 's, jets and/or higgses, plus missing energy. In order
to characterize these signatures, we define a small number of minimal spectra,
in the context of General Gauge Mediation, which are parameterized by the mass
of the NLSP and the gluino. Using these minimal spectra, we determine the most
promising discovery channels for general neutralino NLSPs. We find that the
2010 dataset can already cover new ground with strong production for all NLSP
types. With the upcoming 2011-2012 dataset, we find that the LHC will also have
sensitivity to direct electroweak production of neutralino NLSPs.Comment: 26 page
Cognitive control in belief-laden reasoning during conclusion processing: An ERP study
Belief bias is the tendency to accept conclusions that are compatible with existing beliefs more frequently than those that contradict beliefs. It is one of the most replicated behavioral findings in the reasoning literature. Recently, neuroimaging studies using functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs) have provided a new perspective and have demonstrated neural correlates of belief bias that have been viewed as supportive of dual-process theories of belief bias. However, fMRI studies have tended to focus on conclusion processing, while ERPs studies have been concerned with the processing of premises. In the present research, the electrophysiological correlates of cognitive control were studied among 12 subjects using high-density ERPs. The analysis was focused on the conclusion presentation phase and was limited to normatively sanctioned responses to valid–believable and valid–unbelievable problems. Results showed that when participants gave normatively sanctioned responses to problems where belief and logic conflicted, a more positive ERP deflection was elicited than for normatively sanctioned responses to nonconflict problems. This was observed from −400 to −200 ms prior to the correct response being given. The positive component is argued to be analogous to the late positive component (LPC) involved in cognitive control processes. This is consistent with the inhibition of empirically anomalous information when conclusions are unbelievable. These data are important in elucidating the neural correlates of belief bias by providing evidence for electrophysiological correlates of conflict resolution during conclusion processing. Moreover, they are supportive of dual-process theories of belief bias that propose conflict detection and resolution processes as central to the explanation of belief bias
Oxidation resistance of graphene-coated Cu and Cu/Ni alloy
The ability to protect refined metals from reactive environments is vital to
many industrial and academic applications. Current solutions, however,
typically introduce several negative effects, including increased thickness and
changes in the metal physical properties. In this paper, we demonstrate for the
first time the ability of graphene films grown by chemical vapor deposition to
protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy
from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the
metal surface is well protected from oxidation even after heating at 200
\degree C in air for up to 4 hours. Our work further shows that graphene
provides effective resistance against hydrogen peroxide. This protection method
offers significant advantages and can be used on any metal that catalyzes
graphene growth
Laser locking to the 199Hg clock transition with 5.4x10^(-15)/sqrt(tau) fractional frequency instability
With Hg atoms confined in an optical lattice trap in the Lamb-Dicke regime,
we obtain a spectral line at 265.6 nm in which the full-width at half-maximum
is <15Hz. Here we lock an ultrastable laser to this ultranarrow clock
transition and achieve a fractional frequency stability of
5.4x10^(-15)/sqrt(tau) for tau<=400s. The highly stable laser light used for
the atom probing is derived from a 1062.6 nm fiber laser locked to an
ultrastable optical cavity that exhibits a mean drift rate of -6.0x10^(-17)
s^(-1) (or -16.9 mHz.s^(-1) at 282 THz) over a five month period. A comparison
between two such lasers locked to independent optical cavities shows a flicker
noise limited fractional frequency instability of 4x10^(-16) per cavity
Childhood Abuse, Neglect, and Household Dysfunction and the Risk of Illicit Drug Use: The Adverse Childhood Experiences Study
Search for the standard model Higgs boson decaying to a pair in events with no charged leptons and large missing transverse energy using the full CDF data set
We report on a search for the standard model Higgs boson produced in
association with a vector boson in the full data set of proton-antiproton
collisions at TeV recorded by the CDF II detector at the
Tevatron, corresponding to an integrated luminosity of 9.45 fb. We
consider events having no identified charged lepton, a transverse energy
imbalance, and two or three jets, of which at least one is consistent with
originating from the decay of a quark. We place 95% credibility level upper
limits on the production cross section times standard model branching fraction
for several mass hypotheses between 90 and . For a Higgs
boson mass of , the observed (expected) limit is 6.7
(3.6) times the standard model prediction.Comment: Accepted by Phys. Rev. Let
Search for the standard model Higgs boson decaying to a bb pair in events with one charged lepton and large missing transverse energy using the full CDF data set
We present a search for the standard model Higgs boson produced in
association with a W boson in sqrt(s) = 1.96 TeV p-pbar collision data
collected with the CDF II detector at the Tevatron corresponding to an
integrated luminosity of 9.45 fb-1. In events consistent with the decay of the
Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a
neutrino, we set 95% credibility level upper limits on the WH production cross
section times the H->bb branching ratio as a function of Higgs boson mass. At a
Higgs boson mass of 125 GeV/c2 we observe (expect) a limit of 4.9 (2.8) times
the standard model value.Comment: Submitted to Phys. Rev. Lett (v2 contains clarifications suggested by
PRL
Search for the standard model Higgs boson decaying to a bb pair in events with two oppositely-charged leptons using the full CDF data set
We present a search for the standard model Higgs boson produced in
association with a Z boson in data collected with the CDF II detector at the
Tevatron, corresponding to an integrated luminosity of 9.45/fb. In events
consistent with the decay of the Higgs boson to a bottom-quark pair and the Z
boson to electron or muon pairs, we set 95% credibility level upper limits on
the ZH production cross section times the H -> bb branching ratio as a function
of Higgs boson mass. At a Higgs boson mass of 125 GeV/c^2 we observe (expect) a
limit of 7.1 (3.9) times the standard model value.Comment: To be submitted to Phys. Rev. Let
Adverse childhood experiences and suicide attempts in morbidly obese adults
Introdução: As tentativas de suicídio surgem frequentemente associadas a problemas alimentares, tanto anorexia quanto bulimia. Do mesmo modo, tem-se verifi cado uma elevada ocorrência de suicídio entre obesos. Investigações têm mostrado que a adversidade na infância pode ser um fator de
risco para as tentativas de suicídio.
Objetivos: Caracterizar e compreender a relação entre experiências de adversidade na infância e tentativas de suicídio em 100 obesos mórbidos
candidatos a cirurgia bariátrica.
Métodos: Um total de 100 pacientes foram selecionados de setembro de 2007 a outubro de 2007 e de janeiro de 2008 a janeiro de 2009, sendo que 20 pacientes eram do sexo feminino. A média de idade era de 38,89±9,87 anos, e a média do peso máximo era de 136,43±14 kg. O Questionário da
História de Adversidade na Infância foi utilizado para avaliar experiências adversas.
Resultados: 88% dos pacientes relataram a existência de pelo menos uma experiência de adversidade na infância, e 25% relataram já ter realizado pelo menos
uma tentativa de suicídio. A adversidade na infância esteve associada a um risco aumentado para realizar tentativas de suicídio (odds ratio = 2,026).
Conclusão: Esses dados devem ser levados em consideração na avaliação e no acompanhamento desses pacientes.Introduction: Suicide attempts are often associated with eating disorders, both anorexia and bulimia. Likewise, a high incidence of suicide has been
observed among obese patients. Previous studies have shown that adverse experiences in childhood may be a risk factor for suicide attempts.
Objectives: To characterize and to understand the relationship between adverse experiences and suicide attempts in 100 morbidly obese patients
referred for bariatric surgery.
Methods: A total of 100 patients were selected from September 2007 to October 2007 and from January 2008 to January 2009. Of these, 20 patients
were females. Mean age was 38.89±9.87 years, and mean maximum weight was 136.43±14 kg. The Portuguese version of the Family ACE (Adverse
Childhood Experiences) Questionnaire was used to assess the occurrence of adverse events.
Results: 88% of the patients reported the existence of at least one adverse experience in childhood, and 25% reported at least one previous suicide
attempt. Adversity in childhood was associated with an increased risk for suicide attempts (odds ratio = 2.026).
Conclusion: These data should be taken into account in the assessment and monitoring of these patients.Fundação para a Ciência e a Tecnologia (FCT); (SFRH/BD/37069/2007)
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