16,154 research outputs found
A Conversation with Monroe Sirken
Born January 11, 1921 in New York City, Monroe Sirken grew up in a suburb of
Pasadena, California. He earned B.A. and M.A. degrees in sociology at UCLA in
1946 and 1947, and a Ph.D. in 1950 in sociology with a minor in mathematics at
the University of Washington in 1950 where Professor Z. W. Birnbaum was his
mentor and thesis advisor. As a Post-Doctoral Fellow of the Social Science
Research Council, Monroe spent 1950--1951 at the Statistics Laboratory,
University of California at Berkeley and the Office of the Assistant Director
for Research, U.S. Bureau of the Census in Suitland, Maryland. Monroe visited
the Census Bureau at a time of great change in the use of sampling and survey
methods, and decided to remain. He began his government career there in 1951 as
a mathematical statistician, and moved to the National Office of Vital
Statistics (NOVS) in 1953 where he was an actuarial mathematician and a
mathematical statistician. He has held a variety of research and administrative
positions at the National Center for Health Statistics (NCHS) and he was the
Associate Director, Research and Methodology and the Director, Office of
Research and Methodology until 1996 when he became a senior research scientist,
the title he currently holds. Aside from administrative responsibilities,
Monroe's major professional interests have been conducting and fostering survey
and statistical research responsive to the needs of federal statistics. His
interest in the design of rare and sensitive population surveys led to the
development of network sampling which improves precision by linking multiple
selection units to the same observation units. His interest in fostering
research on the cognitive aspects of survey methods led to the establishment of
permanent questionnaire design research laboratories, first at NCHS and later
at other federal statistical agencies here and abroad.Comment: Published in at http://dx.doi.org/10.1214/07-STS245 the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Head-on collisions of boson stars
We study head-on collisions of boson stars in three dimensions. We consider
evolutions of two boson stars which may differ in their phase or have opposite
frequencies but are otherwise identical. Our studies show that these phase
differences result in different late time behavior and gravitational wave
output
Hysteresis Switching Loops in Ag-manganite memristive interfaces
Multilevel resistance states in silver-manganite interfaces are studied both
experimentally and through a realistic model that includes as a main ingredient
the oxygen vacancies diffusion under applied electric fields. The switching
threshold and amplitude studied through Hysteresis Switching Loops are found to
depend critically on the initial state. The associated vacancy profiles further
unveil the prominent role of the effective electric field acting at the
interfaces. While experimental results validate main assumptions of the model,
the simulations allow to disentangle the microscopic mechanisms behind the
resistive switching in metal-transition metal oxide interfaces.Comment: 14 pages, 3 figures, to be published in Jour. of Appl. Phy
Constraining the initial temperature and shear viscosity in a hybrid hydrodynamic model of =200 GeV Au+Au collisions using pion spectra, elliptic flow, and femtoscopic radii
A new framework for evaluating hydrodynamic models of relativistic heavy ion
collisions has been developed. This framework, a Comprehesive Heavy Ion Model
Evaluation and Reporting Algorithm (CHIMERA) has been implemented by augmenting
UVH 2+1D viscous hydrodynamic model with eccentricity fluctuations,
pre-equilibrium flow, and the Ultra-relativistic Quantum Molecular Dynamic
(UrQMD) hadronic cascade. A range of initial temperatures and shear viscosity
to entropy ratios were evaluated for four initial profiles, and
scaling with and without pre-equilibrium flow. The model results
were compared to pion spectra, elliptic flow, and femtoscopic radii from 200
GeV Au+Au collisions for the 0--20% centrality range.Two sets of initial
density profiles, scaling with pre-equilibrium flow and
scaling without were shown to provide a consistent description of all three
measurements.Comment: 21 pages, 32 figures, version 3 includes additional text for
clarification, division of figures into more manageable units, and placement
of chi-squared values in tables for ease of viewin
A Gentle Ethical Defence of Homeopathy
Recent discourses about the legitimacy of homeopathy have focused on its scientific plausibility, mechanism of action and evidence base. These, frequently, conclude not only that homeopathy is scientifically baseless, but that it is ‘unethical.’ They have also diminished patients’ perspectives, values and preferences. We contend that these critics confuse epistemic questions with questions of ethics; misconstrue the moral status of homeopaths and have an impoverished idea of ethics – one that fails to account either for the moral worth of care and of relationships, or for the perspectives, values and preferences of patients. Utilitarian critics, in particular, endeavour to present an objective evaluation – a type of moral calculus – quantifying the utilities and disutilities of homeopathy as a justification for the exclusion of homeopathy from research and healthcare. But these critiques are built upon a narrow formulation of evidence and care, and a diminished episteme that excludes the values and preferences of researchers, homeopaths and patients engaged in the practice of homeopathy. We suggest that homeopathy is ethical as it fulfils the needs and expectations of many patients; may be practiced safely and prudentially; values care and the virtues of the therapeutic relationship; and provides important benefits for patients. Keywords Homeopathy, ethics, utilitarian, patient values and preferences, evidence, EBM, outcome
The hard scale in the exclusive rho-meson production in diffractive DIS
We re-examine the issue of the pQCD factorization scale in the exclusive rho
production in diffractive DIS from the k_t-factorization point of view. We find
that this scale differs significantly from, and possesses much flatter Q^2
behavior than widely used value (Q^2 + m_\rho^2)/4. With these results in mind,
we discuss the Q^2 shape of the rho meson production cross section. We
introduce rescaled cross sections, which might provide further insight into the
dynamics of rho production. We also comment on the recent ZEUS observation of
energy-independent ratio sigma(gamma* p --> rho p) / sigma_{tot}(gamma*p).Comment: 14 pages, 7 eps figure
Statistics of the One-Electron Current in a One-Dimensional Mesoscopic Ring at Arbitrary Magnetic Fields
The set of moments and the distribution function of the one-electron current
in a one-dimensional disordered ring with arbitrary magnetic flux are
calculated.Comment: 10 pages; Plain TeX; IFUM 448/FT; to appear in J. Stat. Phy
Determining the Surface-To-Bulk Progression in the Normal-State Electronic Structure of Sr2RuO4 by Angle-Resolved Photoemission and Density Functional Theory
In search of the potential realization of novel normal-state phases on the
surface of Sr2RuO4 - those stemming from either topological bulk properties or
the interplay between spin-orbit coupling (SO) and the broken symmetry of the
surface - we revisit the electronic structure of the top-most layers by ARPES
with improved data quality as well as ab-initio LDA slab calculations. We find
that the current model of a single surface layer (\surd2x\surd2)R45{\deg}
reconstruction does not explain all detected features. The observed
depth-dependent signal degradation, together with the close quantitative
agreement with LDA+SO slab calculations based on the LEED-determined surface
crystal structure, reveal that (at a minimum) the sub-surface layer also
undergoes a similar although weaker reconstruction. This points to a
surface-to-bulk progression of the electronic states driven by structural
instabilities, with no evidence for Dirac and Rashba-type states or surface
magnetism.Comment: 4 pages, 4 figures, 1 table. Further information and PDF available
at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm
Measuring shared variants in cohorts of discordant siblings with applications to autism
We develop a method of analysis [affected to discordant sibling pairs (A2DS)] that tests if shared variants contribute to a disorder. Using a standard measure of genetic relation, test individuals are compared with a cohort of discordant sibling pairs (CDS) to derive a comparative similarity score. We ask if a test individual is more similar to an unrelated affected than to the unrelated unaffected sibling from the CDS and then, sum over such individuals and pairs. Statistical significance is judged by randomly permuting the affected status in the CDS. In the analysis of published genotype data from the Simons Simplex Collection (SSC) and the Autism Genetic Resource Exchange (AGRE) cohorts of children with autism spectrum disorder (ASD), we find strong statistical significance that the affected are more similar to the affected than to the unaffected of the CDS (P value approximately 0.00001). Fathers in multiplex families have marginally greater similarity (P value = 0.02) to unrelated affected individuals. These results do not depend on ethnic matching or gender
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