1,949 research outputs found
Scaling of the conductance distribution near the Anderson transition
The single parameter scaling hypothesis is the foundation of our
understanding of the Anderson transition. However, the conductance of a
disordered system is a fluctuating quantity which does not obey a one parameter
scaling law. It is essential to investigate the scaling of the full conductance
distribution to establish the scaling hypothesis. We present a clear cut
numerical demonstration that the conductance distribution indeed obeys one
parameter scaling near the Anderson transition
Uniform cross phase modulation for nonclassical radiation pulses
We propose a scheme to achieve a uniform cross phase modulation (XPM) for two
nonclassical light pulses and study its application for quantum non-demolition
measurements of the photon number in a pulse and for controlled phase gates in
quantum information. We analyze the scheme by quantizing a common
phenomenological model for classical XPM. Our analysis first treats the ideal
case of equal cross-phase modulation and pure unitary dynamics. This
establishes the groundwork for more complicated studies of non-unitary dynamics
and difference in phase shifts between the two pulses where decohering effects
severely affect the performance of the scheme.Comment: 11 pages, 4 figures. To appear in J. Opt. Soc. Am.
Feedback cooling of a single trapped ion
Based on a real-time measurement of the motion of a single ion in a Paul
trap, we demonstrate its electro-mechanical cooling below the Doppler limit by
homodyne feedback control (cold damping). The feedback cooling results are well
described by a model based on a quantum mechanical Master Equation.Comment: 4 pages, 3 figure
The Internationalists: How a Radical Plan to Outlaw War Remade the World
Oona A. Hathaway and Scott J. Shapiro. The Internationalists: How a Radical Plan to Outlaw War Remade the World. New York: Simon & Schuster, 2017. ISBN: 9781501109874 (paperback, $20.00)
The Internationalists: How a Radical Plan to Outlaw War Remade the World
Oona A. Hathaway and Scott J. Shapiro. The Internationalists: How a Radical Plan to Outlaw War Remade the World. New York: Simon & Schuster, 2017. ISBN: 9781501109874 (paperback, $20.00)
Simple, Defensible Sample Sizes Based on Cost Efficiency -- With Discussion and Rejoinder
The conventional approach of choosing sample size to provide 80% or greater power ignores the cost implications of different sample size choices. Costs, however, are often impossible for investigators and funders to ignore in actual practice. Here, we propose and justify a new approach for choosing sample size based on cost efficiency, the ratio of a study’s projected scientific and/or practical value to its total cost. By showing that a study’s projected value exhibits diminishing marginal returns as a function of increasing sample size for a wide variety of definitions of study value, we are able to develop two simple choices that can be defended as more cost efficient than any larger sample size. The first is to choose the sample size that minimizes the average cost per subject. The second is to choose sample size to minimize total cost divided by the square root of sample size. This latter method is theoretically more justifiable for innovative studies, but also performs reasonably well and has some justification in other cases. For example, if projected study value is assumed to be proportional to power at a specific alternative and total cost is a linear function of sample size, then this approach is guaranteed either to produce more than 90% power or to be more cost efficient than any sample size that does. These methods are easy to implement, based on reliable inputs, and well justified, so they should be regarded as acceptable alternatives to current conventional approaches
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Exposure to tricyclic antidepressants is associated with an increased risk of incident CHD events in a population-based study
Purpose
The purpose of this study was to assess the association between antidepressant use and incident coronary heart disease (CHD) events in a sample of individuals without known baseline heart disease.
Participants and methods
We studied a group of 970 randomly selected community-dwelling adults in the 1995 Nova Scotia Health Survey, who were followed for up to 10 years. Antidepressant usage was classified according to class. Primary outcomes were acute coronary syndrome hospitalizations or cardiac death, determined by centralized, standardized ratings.
Results
During a follow-up period of 10 years, there were 147 incident CHD events (139 acute coronary syndromes and 8 cardiac deaths) during the 8129 person-years of observation (incidence rate=18.1 events/1000 person-years). In a model controlling for age, sex, Framingham risk score, time to last annual exam, aspirin exposure, and depressive symptoms, an increased risk of CHD events was associated with tricyclic antidepressant exposure (adjusted hazard ratio, 2.10; 95% confidence interval, 1.09–4.06; p =0.027).
Conclusion
In this prospective population-based study, exposure to tricyclic antidepressants was associated with higher risk of first CHD events
Probability distribution of the conductance at the mobility edge
Distribution of the conductance P(g) at the critical point of the
metal-insulator transition is presented for three and four dimensional
orthogonal systems. The form of the distribution is discussed. Dimension
dependence of P(g) is proven. The limiting cases and are
discussed in detail and relation in the limit is proven.Comment: 4 pages, 3 .eps figure
Symmetry, dimension and the distribution of the conductance at the mobility edge
The probability distribution of the conductance at the mobility edge,
, in different universality classes and dimensions is investigated
numerically for a variety of random systems. It is shown that is
universal for systems of given symmetry, dimensionality, and boundary
conditions. An analytical form of for small values of is discussed
and agreement with numerical data is observed. For , is
proportional to rather than .Comment: 4 pages REVTeX, 5 figures and 2 tables include
Short Term Development and Fate of MGE-Like Neural Progenitor Cells in Jaundiced and Non-Jaundiced Rat Brain
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.Neonatal hyperbilirubinemia targets specific brain regions and can lead to kernicterus. One of the most debilitating symptoms of kernicterus is dystonia, which results from bilirubin toxicity to the globus pallidus (GP). Stem cell transplantation into the GP to replace lost neurons and restore basal ganglia circuits function is a potential therapeutic strategy to treat dystonia in kernicterus. In this study we transplanted human medial ganglionic eminence (MGE)-like neural progenitor cells (NPCs) that we differentiated into a primarily gamma-aminobutyric acid (GABA)ergic phenotype, into the GP of non-immunosuppressed jaundiced (jj) and non-jaundiced (Nj) rats. We assessed the survival and development of graft cells at three time-points post-transplantation. While grafted MGE-like NPCs survived and generated abundant fibers in both jj and Nj brains, NPC survival was greater in the jj brain. These results were consistent with our previous finding that excitatory spinal interneuron-like NPCs exhibited a higher survival rate in the jj brain than in the Nj brain. Our findings further support our hypothesis that slightly elevated bilirubin levels in the jj brain served as an antioxidant and immunosuppressant to protect the transplanted cells. We also identified graft fibers growing toward brain regions that receive projections from the GP, as well as host fibers extending toward the graft. These promising findings suggest that MGE-like NPCs may have the capacity to restore the circuits connecting GP and other nuclei.NIH Center of Biomedical Research Excellence program project P20 GM104936Children's Mercy HospitalRonald D. Deffenbaugh FoundationKansas Intellectual and Developmental Disabilities Research Center HD09021
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