1,499 research outputs found
Limited measurement dependence in multiple runs of a Bell test
The assumption of free will - the ability of an experimentalist to make
random choices - is central to proving the indeterminism of quantum resources,
the primary tool in quantum cryptography. Relaxing the assumption in a Bell
test allows violation of the usual classical threshold by correlating the
random number generators used to select measurements with the devices that
perform them. In this paper, we examine not only these correlations, but those
across multiple runs of the experiment. This enables an explicit exposition of
the optimal cheating strategy and how the correlations manifest themselves
within this strategy. Similar to other recent results, we prove that there
remain Bell violations for a sufficiently high, yet non-maximal degree of free
will which cannot be simulated by a classical attack, regardless of how many
runs of the experiment those choices are correlated over.Comment: 8 pages, 3 figures. Version 2 reflects the published paper in
Physical Review A, which among some minor additions/changes now includes
Section V discussing the numerical approach to Bell inequalities other than
CHS
Variant N=(1,1) Supergravity and (Minkowski)_4 x S^2 Vacua
We construct the fermionic sector and supersymmetry transformation rules of a
variant N=(1,1) supergravity theory obtained by generalized Kaluza-Klein
reduction from seven dimensions. We show that this model admits both
(Minkowski)_4 x S^2 and (Minkowski)_3 x S^3 vacua. We perform a consistent
Kaluza-Klein reduction on S^2 and obtain D=4, N=2 supergravity coupled to a
vector multiplet, which can be consistently truncated to give rise to D=4, N=1
supergravity with a chiral multiplet.Comment: Latex, 17 pages. Version appearing in Classical and Quantum Gravit
Supergravities with Minkowski x Sphere Vacua
Recently the authors have introduced a new gauged supergravity theory with a
positive definite potential in D=6, obtained through a generalised Kaluza-Klein
reduction from D=7. Of particular interest is the fact that this theory admits
certain Minkowski x Sphere vacua. In this paper we extend the previous results
by constructing gauged supergravities with positive definitive potentials in
diverse dimensions, together with their vacuum solutions. In addition, we prove
the supersymmetry of the generalised reduction ansatz. We obtain a
supersymmetric solution with no form-field fluxes in the new gauged theory in
D=9. This solution may be lifted to D=10, where it acquires an interpretation
as a time-dependent supersymmetric cosmological solution supported purely by
the dilaton. A further uplift to D=11 yields a solution describing a pp-wave.Comment: Latex, 26 pages, typos correcte
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Avoiding Randomization Failure in Program Evaluation, with Application to the Medicare Health Support Program
We highlight common problems in the application of random treatment assignment in large-scale program evaluation. Random assignment is the defining feature of modern experimental design, yet errors in design, implementation, and analysis often result in real-world applications not benefiting from its advantages. The errors discussed here cover the control of variability, levels of randomization, size of treatment arms, and power to detect causal effects, as well as the many problems that commonly lead to post-treatment bias. We illustrate these issues by identifying numerous serious errors in the Medicare Health Support evaluation and offering
recommendations to improve the design and analysis of this and other large-scale randomized experiments.Governmen
National Athletic Trainers\u27 Association Position Statement: Anabolic-Androgenic Steroids
Objective: This manuscript summarizes the best available scholarly evidence related to anabolic-androgenic steroids (AAS) as a reference for health care professionals, including athletic trainers, educators, and interested others.
Background: Health care professionals associated with sports or exercise should understand and be prepared to educate others about AAS. These synthetic, testosteronebased derivatives are widely abused by athletes and nonathletes to gain athletic performance advantages, develop their physiques, and improve their body image. Although AAS can be ergogenic, their abuse may lead to numerous negative health effects.
Recommendations: Abusers of AAS often rely on questionable information sources. Sports medicine professionals can therefore serve an important role by providing accurate, reliable information. The recommendations provide health care professionals with a current and accurate synopsis of the AAS-related research
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Survey to explore understanding of the principles of aseptic technique: Qualitative content analysis with descriptive analysis of confidence and training
BACKGROUND: In many countries, aseptic procedures are undertaken by nurses in the general ward setting, but variation in practice has been reported, and evidence indicates that the principles underpinning aseptic technique are not well understood.
METHODS: A survey was conducted, employing a brief, purpose-designed, self-reported questionnaire.
RESULTS: The response rate was 72%. Of those responding, 65% of nurses described aseptic technique in terms of the procedure used to undertake it, and 46% understood the principles of asepsis. The related concepts of cleanliness and sterilization were frequently confused with one another. Additionally, 72% reported that they not had received training for at least 5 years; 92% were confident of their ability to apply aseptic technique; and 90% reported that they had not been reassessed since their initial training. Qualitative analysis confirmed a lack of clarity about the meaning of aseptic technique.
CONCLUSION: Nurses' understanding of aseptic technique and the concepts of sterility and cleanliness is inadequate, a finding in line with results of previous studies. This knowledge gap potentially places patients at risk. Nurses' understanding of the principles of asepsis could be improved. Further studies should establish the generalizability of the study findings. Possible improvements include renewed emphasis during initial nurse education, greater opportunity for updating knowledge and skills post-qualification, and audit of practice
Varicella-zoster virus induces apoptosis in cell culture
peer reviewedaudience: researcherApoptosis is an active mechanism of cell death which can be initiated in response to various stimuli including virus infections. In this work, we demonstrate that lytic infection by varicella-zoster virus (VZV), a human herpesvirus, is characterized by nuclear fragmentation of DNA into oligonucleosomal fragments and by chromatin condensation. In vitro, VZV-induced cell death is actually mediated by apoptosis. The mechanisms developed by cells to protect themselves against apoptosis could be one of the parameters allowing the establishment of virus latency. In the case of VZV, which can remain latent in sensory ganglia, we have not yet identified a cellular or viral protein which could play this protective role, since the observed apoptosis mechanism seems to be independent from Bcl-2, the most frequently described inhibitor of apoptosis
Bitwise Bell inequality violations for an entangled state involving 2N ions
Following on from previous work [J. A. Larsson, Phys. Rev. A 67, 022108
(2003)], Bell inequalities based on correlations between binary digits are
considered for a particular entangled state involving 2N trapped ions. These
inequalities involve applying displacement operations to half of the ions and
then measuring correlations between pairs of corresponding bits in the binary
representations of the number of centre-of-mass phonons of N particular ions.
It is shown that the state violates the inequalities and thus displays
nonclassical correlations. It is also demonstrated that it violates a Bell
inequality when the displacements are replaced by squeezing operations.Comment: 12 pages, 5 figures, accepted for publication in Phys. Rev.
Optical spectra and exchange-correlation effects in molecular crystals
We report first-principles GW-Bethe Salpeter Equation and Quantum Monte Carlo
calculations of the optical and electronic properties of molecular and
crystalline rubrene (CH). Many-body effects dominate the optical
spectrum and quasi-particle gap of molecular crystals. We interpret the
observed yellow-green photoluminescence in rubrene microcrystals as a result of
the formation of intermolecular, charge-transfer spin-singlet excitons. In
contrast, spin-triplet excitons are localized and intramolecular with a
predicted phosphorescence at the red end of the optical spectrum. We find that
the exchange energy plays a fundamental role in raising the energy of
intramolecular spin-singlet excitons above the intermolecular ones. Exciton
binding energies are predicted to be around 0.5 eV (spin singlet) to 1 eV (spin
triplet). The calculated electronic gap is 2.8 eV. The theoretical absorption
spectrum agrees very well with recent ellipsometry data.Comment: 4 pages, 4 figure
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