21,791 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
Magnetorotational-type instability in Couette-Taylor flow of a viscoelastic polymer liquid
We describe an instability of viscoelastic Couette-Taylor flow that is
directly analogous to the magnetorotational instability (MRI) in astrophysical
magnetohydrodynamics, with polymer molecules playing the role of magnetic field
lines. By determining the conditions required for the onset of instability and
the properties of the preferred modes, we distinguish it from the centrifugal
and elastic instabilities studied previously. Experimental demonstration and
investigation should be much easier for the viscoelastic instability than for
the MRI in a liquid metal. The analogy holds with the case of a predominantly
toroidal magnetic field such as is expected in an accretion disk and it may be
possible to access a turbulent regime in which many modes are unstable.Comment: 4 pages, 4 figures, to be published in Physical Review Letter
On charged impurity structures in liquid helium
The thermoluminescence spectra of impurity-helium condensates (IHC) submerged in superfluid helium have
been observed for the first time. Thermoluminescence of impurity-helium condensates submerged in superfluid
helium is explained by neutralization reactions occurring in impurity nanoclusters. Optical spectra of excited
products of neutralization reactions between nitrogen cations and thermoactivated electrons were rather different
from the spectra observed at higher temperatures, when the luminescence due to nitrogen atom recombination
dominates. New results on current detection during the IHC destruction are presented. Two different mechanisms
of nanocluster charging are proposed to describe the phenomena observed during preparation and warmup
of IHC samples in bulk superfluid helium, and destruction of IHC samples out of liquid helium
Cosmology With A Dark Refraction Index
We review Gordon's optical metric and the transport equations for the
amplitude and polarization of a geometrical optics wave traveling in a gravity
field. We apply the theory to the FLRW cosmologies by associating a refraction
index with the cosmic fluid. We then derive an expression for the accumulated
effect of a refraction index on the distance redshift relations and fit the
Hubble curve of current supernova observations with a non-accelerating
cosmological model. We also show that some observational effects caused by
inhomogeneities, e.g. the Sachs-Wolfe effect, can be interpreted as being
caused by an effective index of refraction, and hence this theory could extend
to other speed of light communications such as gravitational radiation and
neutrino fluxes.Comment: 21 pages, 3 figure
Books
Portrait of Don Craib In Search of Truth - A Portrait of Don Craib: By E.B. Adams pp. xi + 123. Illustrated.London and New York: Royal Society of Medicine Services. 1990.Internal medicine Harrison's Principles of Internal Medicine. 12th ed. Bd. by ].D. Wilson, E. Braunwald, K.]. Isselbacher, et al. pp. xxx + 2208. Illustrated. USA: McGraw-Hill. 1991.HPV and cervical cancer Human Papillomavirus and Cervical Cancer. Ed. by N. Munoz, F. X. Bosch and O. M. Jensen. Pp. xii + 155. Illustrated. France: International Agency for Research on Cancer. 1989
Energy corrections of order mc2α6lnα in helium
Quantum-electrodynamic corrections of O(mc2α6lnα) to the electron-electron interaction in helium are evaluated for several states. The additional energy shift, which is an order of α smaller than the leading Araki-Sucher terms, raises the predicted energy of the 1s2s 1S0 state by 2.49 MHz to -960 332 039.43(18) MHz relative to He+(1s). The new value significantly alters the comparison with recent high-precision experiments. © 1993 The American Physical Society
Rival bishops, rival cathedrals : the election of Cormac, archdeacon of Sodor, as bishop in 1331
Peer reviewedPublisher PD
Hubbard ring: currents induced by change of magnetic flux
We investigate currents in a quantum ring threaded by a magnetic flux which
can be varied in an arbitrary way from an initial value at time
to a final value at time . Dynamics of electrons in the ring is
described by the Hubbard and the extended Hubbard models. We demonstrate that
time dependence of the induced current bears information on electron
correlations. In the case of the Hubbard model with infinite on--site repulsion
we prove that the current for is independent of the flux variation
before . Additionally, this current is fully determined by a solution of
the initial equilibrium problem and the value of . Apart from
mesoscopic rings our results pose important implications for designing of
quantum motors built out as the ring--shaped optical lattice
Axial anomaly and the three-flavor Nambu--Jona-Lasinio model with confinement: Constructing the QCD phase diagram
We investigate the phase structure of massless three-flavor QCD by extending
the Nambu-Jona- Lasinio model to include the effects of confinement and the
axial anomaly. We study the interplay between the chiral and diquark
condensates induced by the axial anomaly, as well as their relationship with
the Polyakov loop, which parameterizes confinement. By minimizing the
thermodynamic potential we construct the QCD phase diagram and investigate the
possibility of realizing a recently discovered low temperature critical point
and an associated BEC-BCS crossover. We also perform a Ginzburg-Landau
expansion of the thermodynamic potential, comparing our results to a prior
analysis based purely on symmetry considerations, in order to assess the
lowest-order effects of the condensate-confinement couplings.Comment: 13 pages, 14 figure
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