5,188 research outputs found
Optimal Bell tests do not require maximally entangled states
Any Bell test consists of a sequence of measurements on a quantum state in
space-like separated regions. Thus, a state is better than others for a Bell
test when, for the optimal measurements and the same number of trials, the
probability of existence of a local model for the observed outcomes is smaller.
The maximization over states and measurements defines the optimal nonlocality
proof. Numerical results show that the required optimal state does not have to
be maximally entangled.Comment: 1 figure, REVTEX
Nonconcave entropies from generalized canonical ensembles
It is well-known that the entropy of the microcanonical ensemble cannot be
calculated as the Legendre transform of the canonical free energy when the
entropy is nonconcave. To circumvent this problem, a generalization of the
canonical ensemble which allows for the calculation of nonconcave entropies was
recently proposed. Here, we study the mean-field Curie-Weiss-Potts spin model
and show, by direct calculations, that the nonconcave entropy of this model can
be obtained by using a specific instance of the generalized canonical ensemble
known as the Gaussian ensemble.Comment: 5 pages, RevTeX4, 3 figures (best viewed in ps
Field-calibrated model of melt, refreezing, and runoff for polar ice caps : Application to Devon Ice Cap
Acknowledgments R.M.M. was supported by the Scottish Alliance for Geoscience, Environment and Society (SAGES). The field data collection contributed to the validation of the European Space Agency Cryosat mission and was supported by the Natural Sciences and Engineering Research Council, Canada, the Meteorological Service of Canada (CRYSYS program), the Polar Continental Shelf Project (an agency of Natural Resources Canada), and by UK Natural Environment Research Council consortium grant NER/O/S/2003/00620. Support for D.O.B. was provided by the Canadian Circumpolar Institute and the Climate Change Geoscience Program, Earth Sciences Sector, Natural Resources Canada (ESS contribution 20130371). Thanks are also due to the Nunavut Research Institute and the communities of Resolute Bay and Grise Fjord for permission to conduct fieldwork on Devon Ice Cap. M.J. Sharp, A. Gardner, F. Cawkwell, R. Bingham, S. Williamson, L. Colgan, J. Davis, B. Danielson, J. Sekerka, L. Gray, and J. Zheng are thanked for logistical support and field assistance during the data collection. We thank Ruzica Dadic, two other anonymous reviewers, and the Editor, Bryn Hubbard, for their helpful comments on an earlier version of this paper and which resulted in significant improvements.Peer reviewedPublisher PD
Substituting Quantum Entanglement for Communication
We show that quantum entanglement can be used as a substitute for
communication when the goal is to compute a function whose input data is
distributed among remote parties. Specifically, we show that, for a particular
function among three parties (each of which possesses part of the function's
input), a prior quantum entanglement enables one of them to learn the value of
the function with only two bits of communication occurring among the parties,
whereas, without quantum entanglement, three bits of communication are
necessary. This result contrasts the well-known fact that quantum entanglement
cannot be used to simulate communication among remote parties.Comment: 4 pages REVTeX, no figures. Minor correction
Multi-scale chemistry modelling for spacecraft atmospheric re-entry
We aim to develop a model capable of simulating the surface chemistry and material erosion involved when a re-entry vehicle descends through the atmosphere. Our starting point is to simulate the erosion of a fcc crystal slab due to cluster bombardment, using the model Lennard-Jones potential. From this, we plan to scale up towards Direct Monte Carlo Simulation approaches for the gas dynamics above the surface
Pulmonary Microembolism in the Canine Model: Report of a Pilot Study
Use of in-line final filters to prevent the infusion of foreign particulates has lowered the rates of postinfusion phlebitis in several controlled studies. The systemic effect of particulate infusion, however, has not been thoroughly studied. In this study, 12 mongrel dogs recovering from a right pneumonectomy were studied following infusion of various-sized particulates. Ten of the dogs were infused with either 10 or 40 million, 9 or 25 μm, latex particles. The remaining two dogs were control animals. Hemodynamic parameters were monitored in each animal. At death or 72 hours following particle injection, the left lung was examined grossly and histologically. Changes in hemodynamic parameters were not seen. Three of the dogs became clinically ill 48 hours following microsphere injection. All dogs injected with particles had multiple discrete punctate areas of hemorrhagic pulmonary infarction. The control dogs showed no sign of clinical illness or pulmonary injury. More sophisticated animal and human studies are required to fully determine the physiologic effect of injected particles
Polymorphism in cyclohexanol
The crystal structures and phase behaviour of phase II and the metastable phases III0 and III of cyclohexanol, C6H11OH,
have been determined using high-resolution neutron powder,
synchrotron X-ray powder and single-crystal X-ray diffraction techniques. Cyclohexanol-II is formed by a transition from the plastic phase I cubic structure at 265 K and crystallizes in a tetragonal structure, space group P�4421c (Z0 = 1), in which the molecules are arranged in a hydrogen-bonded tetrameric ring motif. The structures of phases III0 and III are monoclinic, space groups P21/c (Z0 = 3) and Pc (Z0 = 2), respectively, and are characterized by the formation of hydrogen-bonded molecular chains with a threefold-helical and wave-like nature, respectively. Phase III crystallizes at 195 K from a sample of phase I that is supercooled to ca 100 K. Alternatively, phase III may be grown via phase III0, the latter transforming from supercooled phase I at ca 200 K. Phase III0 is particularly unstable and is metastable with respect to both I and II. Its growth is realised only under very restricted conditions, thus making its characterization especially
challenging. The cyclohexanol molecules adopt a chair
conformation in all three phases with the hydroxyl groups in
an equatorial orientation. No evidence was found indicating
hydroxyl groups adopting an axial orientation, contrary to the majority of spectroscopic literature on solid-state cyclohexanol; however, the H atom of the equatorial OH groups is found to adopt both in-plane and out-of-plane orientations
Accretion discs models with the "beta"-viscosity prescription derived from laboratory experiments
We examine under which conditions one may apply, to steady state keplerian
accretion discs, the "beta"-viscosity prescription which has been derived from
rotating shear flow experiments (Richard & Zahn 1999). Using a vertically
averaged model, we show that this law may be suitable for all three families of
known systems: in young stellar objects, evolved binary stars and Active
Galactic Nuclei discs (except in their outer gas pressure dominated regions
where turbulence becomes hypersonic). According to the standard criterion for
viscous stability, "beta"-discs are always stable throughout. Using realistic
opacities and equation of state, we demonstrate that these discs are thermally
unstable in the temperature domain where hydrogen recombines, when they are
optically thick, and this could lead to limit cycle behavior. Radiation
pressure dominated regions are thermally stable, in contrast with
"alpha"-discs. This results in a fully stable solution for the innermost parts
of AGN discs.Comment: 8 pages, PostScript. accepted in Astron. & Astrophy
The relationship between facility‐based delivery and maternal and neonatal mortality in Sub‐Saharan Africa
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135613/1/ijgo263.pd
Soil nitrogen storage and availability to crops are increased by conservation agriculture practices in rice-based cropping systems in the eastern Gangetic Plains
On-farm adoption of minimum soil disturbance and increased residue retention will alter nitrogen (N) dynamics in soils and N fertiliser management in the intensive rice–based triple cropping systems of the Eastern Gangetic Plains. However, the consequences of changes in N forms, N mineralisation and N availability for crops in these cropping systems have not been determined
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