2,024 research outputs found
Output from Bose condensates in tunnel arrays: the role of mean-field interactions and of transverse confinement
We present numerical studies of atomic transport in 3D and 1D models for a
mode-locked, pulsed atom laser as realized by Anderson and Kasevich [Science
281 (1998) 1686] using an elongated Bose condensate of Rb atoms poured
into a vertical optical lattice. From our 3D results we ascertain in a
quantitative manner the role of mean-field interactions in determining the
shape and the size of the pulses in the case of Gaussian transverse
confinement. By comparison with 1D simulations we single out a best-performing
1D reduction of the mean-field interactions, which yields quantitatively useful
predictions for all main features of the matter output.Comment: 12 pages, 2 figure
The housefly Musca domestica as a mechanical vector of Clostridium difficile
Background - Clostridium difficile is a bacterial healthcare-associated infection that may be transferred by houseflies (Musca domestica) due to their close ecological association with humans and cosmopolitan nature. Aim - To determine the ability of M. domestica to transfer C. difficile both mechanically and following ingestion. Methods - M. domestica were exposed to independent suspensions of vegetative cells and spores of C. difficile, then sampled on to selective agar plates immediately postexposure and at 1-h intervals to assess the mechanical transfer of C. difficile. Fly excreta was cultured and alimentary canals were dissected to determine internalization of cells and spores. Findings - M. domestica exposed to vegetative cell suspensions and spore suspensions of C. difficile were able to transfer the bacteria mechanically for up to 4 h upon subsequent contact with surfaces. The greatest numbers of colony-forming units (CFUs) per fly were transferred immediately following exposure (mean CFUs 123.8 +/− 66.9 for vegetative cell suspension and 288.2 +/− 83.2 for spore suspension). After 1 h, this had reduced (21.2 +/− 11.4 for vegetative cell suspension and 19.9 +/− 9 for spores). Mean C. difficile CFUs isolated from the M. domestica alimentary canal was 35 +/− 6.5, and mean C. difficile CFUs per faecal spot was 1.04 +/− 0.58. C. difficile could be recovered from fly excreta for up to 96 h. Conclusion - This study describes the potential for M. domestica to contribute to environmental persistence and spread of C. difficile in hospitals, highlighting flies as realistic vectors of this micro-organism in clinical areas
Dementia Caregiving Research: Expanding and Reframing the Lens of Diversity, Inclusivity, and Intersectionality
This forum expands and reframes the lens of dementia caregiving research among diverse racial and ethnic groups to better understand the unique needs, stressors, and strengths of multicultural and racial-ethnic family caregivers in the United States. By providing more diverse and inclusive knowledge on caregiving to older adults in the United States, we can create a new path forward with regards to caregiving research. Throughout the article, major questions and answers are supported by critiquing some of the caregiving literature. Discussions are provided to help create inclusive ways of conceptualizing caregiving research and using methodological approaches to reflect the diversity of caregivers and care recipients in the United States. Expanding and reframing the conceptual and methodological lens of diversity, inclusivity and intersectionality can provide evidence to support effective policy, practice, and care in addressing the needs of diverse groups of caregivers and older adults living with dementia
Mechanisms of Spontaneous Current Generation in an Inhomogeneous d-Wave Superconductor
A boundary between two d-wave superconductors or an s-wave and a d-wave
superconductor generally breaks time-reversal symmetry and can generate
spontaneous currents due to proximity effect. On the other hand, surfaces and
interfaces in d-wave superconductors can produce localized current-carrying
states by supporting the T-breaking combination of dominant and subdominant
order parameters. We investigate spontaneous currents in the presence of both
mechanisms and show that at low temperature, counter-intuitively, the
subdominant coupling decreases the amplitude of the spontaneous current due to
proximity effect. Superscreening of spontaneous currents is demonstrated to be
present in any d-d (but not s-d) junction and surface with d+id' order
parameter symmetry. We show that this supercreening is the result of
contributions from the local magnetic moment of the condensate to the
spontaneous current.Comment: 4 pages, 5 figures, RevTe
Fractal Structure of Random Matrices
A multifractal analysis is performed on the universality classes of random
matrices and the transition ones.Our results indicate that the eigenvector
probability distribution is a linear sum of two chi-squared distribution
throughout the transition between the universality ensembles of random matrix
theory and Poisson
Matter-wave interferometry in periodic and quasi-periodic arrays
We calculate within a Bose-Hubbard tight-binding model the matter-wave flow
driven by a constant force through a Bose-Einstein condensate of Rb 87 atoms in
various types of quasi-onedimensional arrays of potential wells. Interference
patterns are obtained when beam splitting is induced by creating energy
minigaps either through period doubling or through quasi-periodicity governed
by the Fibonacci series. The generation of such condensate modulations by means
of optical-laser structures is also discussed.Comment: 11 pages, 6 figures. To appear in Opt. Com
Achieving Health Equity in Embedded Pragmatic Trials for People Living with Dementia and Their Family Caregivers
Embedded pragmatic clinical trials (ePCTs) advance research on Alzheimer's disease/Alzheimer's disease and related dementias (AD/ADRD) in real-world contexts; however, health equity issues have not yet been fully considered, assessed, or integrated into ePCT designs. Health disparity populations may not be well represented in ePCTs without special efforts to identify and successfully recruit sites of care that serve larger numbers of these populations. The National Institute on Aging (NIA) Imbedded Pragmatic Alzheimer's disease (AD) and AD-Related Dementias (AD/ADRD) Clinical Trials (IMPACT) Collaboratory's Health Equity Team will contribute to the overall mission of the collaboratory by developing and implementing strategies to address health equity in the conduct of ePCTs and ensure the collaboratory is a national resource for all Americans with dementia. As a first step toward meeting these goals, this article reviews what is currently known about the inclusion of health disparities populations of people living with dementia (PLWD) and their caregivers in ePCTs, highlights unique challenges related to health equity in the conduct of ePCTs, and suggests priority areas in the design and implementation of ePCTs to increase the awareness and avoidance of pitfalls that may perpetuate and magnify healthcare disparities
Sound Propagation in Nematic Fermi Liquid
We study the longitudinal sound propagation in the electronic nematic Fermi
liquid where the Fermi surface is distorted due to the spontaneously broken
rotational symmetry. The behavior of the sound wave in the nematic ordered
state is dramatically different from that in the isotropic Fermi liquid. The
collective modes associated with the fluctuations of the Fermi surface
distortion in the nematic Fermi liquid leads to the strong and anisotropic
damping of the sound wave. The relevance of the nematic Fermi liquid in doped
Mott insulator is discussed.Comment: 4 pages, no figur
On Exceptional Vertex Operator (Super) Algebras
We consider exceptional vertex operator algebras and vertex operator
superalgebras with the property that particular Casimir vectors constructed
from the primary vectors of lowest conformal weight are Virasoro descendents of
the vacuum. We show that the genus one partition function and characters for
simple ordinary modules must satisfy modular linear differential equations. We
show the rationality of the central charge and module lowest weights,
modularity of solutions, the dimension of each graded space is a rational
function of the central charge and that the lowest weight primaries generate
the algebra. We also discuss conditions on the reducibility of the lowest
weight primary vectors as a module for the automorphism group. Finally we
analyse solutions for exceptional vertex operator algebras with primary vectors
of lowest weight up to 9 and for vertex operator superalgebras with primary
vectors of lowest weight up to 17/2. Most solutions can be identified with
simple ordinary modules for known algebras but there are also four conjectured
algebras generated by weight two primaries and three conjectured extremal
vertex operator algebras generated by primaries of weight 3, 4 and 6
respectively.Comment: 37 page
Forces between elongated particles in a nematic colloid
Using molecular dynamics simulations we study the interactions between elongated colloidal particles (length to breath ratio ≫1) in a nematic host. The simulation results are compared to the results of a Landau–de Gennes elastic free energy. We find that depletion forces dominate for the sizes of the colloidal particles studied. The tangential component of the force, however, allows us to resolve the elastic contribution to the total interaction. We find that this contribution differs from the quadrupolar interaction predicted at large separations. The difference is due to the presence of nonlinear effects, namely, the change in the positions and structure of the defects and their annihilation at small separations
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