2,248 research outputs found
Optomechanical circuits for nanomechanical continuous variable quantum state processing
We propose and analyze a nanomechanical architecture where light is used to
perform linear quantum operations on a set of many vibrational modes. Suitable
amplitude modulation of a single laser beam is shown to generate squeezing,
entanglement, and state-transfer between modes that are selected according to
their mechanical oscillation frequency. Current optomechanical devices based on
photonic crystals may provide a platform for realizing this scheme.Comment: 11 pages, 5 figure
Trend tests for the evaluation of exposure-response relationships in epidemiological exposure studies
One possibility for the statistical evaluation of trends in epidemiological exposure studies is the use of a trend test for data organized in a 2 Ă— k contingency table. Commonly, the exposure data are naturally grouped or continuous exposure data are appropriately categorized. The trend test should be sensitive to any shape of the exposure-response relationship. Commonly, a global trend test only determines whether there is a trend or not. Once a trend is seen it is important to identify the likely shape of the exposure-response relationship. This paper introduces a best contrast approach and an alternative approach based on order-restricted information criteria for the model selection of a particular exposure-response relationship. For the simple change point alternative H1 : 1 =.= q <q+1 =. = k an appropriate approach for the identification of a global trend as well as for the most likely shape of that exposure-response relationship is characterized by simulation and demonstrated for real data examples. Power and simultaneous confidence intervals can be estimated as well. If the conditions are fulfilled to transform the exposure-response data into a 2 Ă— k table, a simple approach for identification of a global trend and its elementary shape is available for epidemiologists
Variations in caffeine and chlorogenic acid contents of coffees: what are we drinking?
The effect of roasting of coffee beans and the extraction of ground coffee with different volumes of hot pressurised water on the caffeine and the total caffeoylquinic acids (CQAs) content of the resultant beverages was investigated. While caffeine was stable higher roasting temperatures resulted in a loss of CQAs so that the caffeine/CQA ratio was a good marker of the degree of roasting. The caffeine and CQA content and volume was determined for 104 espresso coffees obtained from coffee shops in Scotland, Italy and Spain, limited numbers of cappuccino coffees from commercial outlets and several instant coffees. The caffeine content ranged from 48–317 mg per serving and CQAs from 6–188 mg. It is evident that the ingestion of 200 mg of caffeine per day can be readily and unwittingly exceeded by regular coffee drinkers. This is the upper limit of caffeine intake from all sources recommended by US and UK health agencies for pregnant women. In view of the variable volume of serving sizes, it is also clear that the term “one cup of coffee” is not a reproducible measurement for consumption, yet it is the prevailing unit used in epidemiology to assess coffee consumption and to link the potential effects of the beverage and its components on the outcome of diseases. More accurate measurement of the intake of coffee and its potentially bioactive components are required if epidemiological studies are to produce more reliable information
On the Wake Structure in Streaming Complex Plasmas
The theoretical description of complex (dusty) plasmas requires multiscale
concepts that adequately incorporate the correlated interplay of streaming
electrons and ions, neutrals, and dust grains. Knowing the effective dust-dust
interaction, the multiscale problem can be effectively reduced to a
one-component plasma model of the dust subsystem. The goal of the present
publication is a systematic evaluation of the electrostatic potential
distribution around a dust grain in the presence of a streaming plasma
environment by means of two complementary approaches: (i) a high precision
computation of the dynamically screened Coulomb potential from the dynamic
dielectric function, and (ii) full 3D particle-in-cell simulations, which
self-consistently include dynamical grain charging and non-linear effects. The
applicability of these two approaches is addressed
Advancing numerics for the Casimir effect to experimentally relevant aspect ratios
Within the scattering theoretical approach, the Casimir force is obtained
numerically by an evaluation of the round trip of an electromagnetic wave
between the objects involved. Recently [Hartmann M et al. 2017, Phys. Rev.
Lett. 119 043901] it was shown that a symmetrization of the scattering operator
provides significant advantages for the numerical evaluation of the Casimir
force in the experimentally relevant sphere-plane geometry. Here, we discuss in
more detail how the symmetrization modifies the scattering matrix in the
multipole basis and how computational time is reduced. As an application, we
discuss how the Casimir force in the sphere-plane geometry deviates from the
proximity force approximation as a function of the geometric parameters.Comment: 9 pages, 8 figure
Sleep quality in the chronic stage of concussion is associated with poorer recovery: A systematic review
A grant from the One-University Open Access Fund at the University of Kansas was used to defray the author's publication fees in this Open Access journal. The Open Access Fund, administered by librarians from the KU, KU Law, and KUMC libraries, is made possible by contributions from the offices of KU Provost, KU Vice Chancellor for Research & Graduate Studies, and KUMC Vice Chancellor for Research. For more information about the Open Access Fund, please see http://library.kumc.edu/authors-fund.xml.Background
Recovery from a concussion varies based on a multitude of factors. One such factor is sleep disturbances. In our prior review, it was observed that in the acute phase, sleep disturbances are predictive of poor outcomes following a concussion. The literature gap remains on how sleep in the chronic phase of recovery affects outcomes.
Objective
To examine the association between sleep quality during the chronic stage of concussion and post-concussion outcomes.
Literature Survey: Literature searches were performed during 1 July to 1 August 2019 in selected databases along with searching grey literature. Out of the 733 results, 702 references were reviewed after duplicate removal.
Methods
Three reviewers independently reviewed and consented on abstracts meeting eligibility criteria (n = 35). The full-text articles were assessed independently by two reviewers. Consensus was achieved, leaving four articles. Relevant data from each study was extracted using a standard data-extraction table. Quality appraisal was conducted to assess potential bias and the quality of articles.
Results
One study included children (18–60 months) and three studies included adolescents and/or adults (ranging 12–35 years). The association between sleep and cognition (two studies), physical activity (one study), and emotion symptoms (one study) was examined. Sleep quality was associated with decreased cognition and emotional symptoms, but not with meeting physical activity guidelines six months post-concussion injury.
Conclusions
The heterogeneity in age of participants and outcomes across studies and limited number of included studies made interpretations difficult. Future studies may consider if addressing sleep quality following concussion will improve outcomes
Proximity force approximation and specular reflection: Application of the WKB limit of Mie scattering to the Casimir effect
The electromagnetic Casimir interaction between two spheres is studied within
the scattering approach using the plane-wave basis. It is demonstrated that the
proximity force approximation (PFA) corresponds to the specular-reflection
limit of Mie scattering. Using the leading-order semiclassical WKB
approximation for the direct reflection term in the Debye expansion for the
scattering amplitudes, we prove that PFA provides the correct leading-order
divergence for arbitrary materials and temperatures in the sphere-sphere and
the plane-sphere geometry. Our derivation implies that only a small section
around the points of closest approach between the interacting spherical
surfaces contributes in the PFA regime. The corresponding characteristic length
scale is estimated from the width of the Gaussian integrand obtained within the
saddle-point approximation. At low temperatures, the area relevant for the
thermal corrections is much larger than the area contributing to the
zero-temperature result.Comment: 13 pages, 3 figure
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