26,063 research outputs found
A Theoretical Growth Model for Ireland
Ireland is distinguished by the high degree of openness of its labour market and the importance of foreign direct investment (FDI) in the economy. We develop a neo-classical growth model to explore the consequence of these characteristics for the response of an economy to the kinds of shocks that are widely recognised to have been of importance in driving the Irish boom.
Neutrino Physics
The basic concepts of neutrino physics are presented at a level appropriate
for integration into elementary courses on quantum mechanics and/or modern
physics.Comment: Prepared for the American Journal of Physics; 50 pages; 11 figures
(10 included); late
The Nature of Solar Polar Rays
We use time series observations from the SOHO and Yohkoh spacecraft to study
solar polar rays. Contrary to our expectations, we find that the rays are
associated with active regions on the sun and are not features of the polar
coronal holes. They are extended, hot plasma structures formed in the active
regions and projected onto the plane of the sky above the polar coronal holes.
We present new observations and simple projection models that match long-lived
polar ray structures seen in limb synoptic maps. Individual projection patterns
last for at least 5 solar rotations.Comment: 10 pages, 5 PostScript figures. Fig.1 is in color. The paper is also
available at http://www.ifa.hawaii.edu/users/jing/papers.htm
Formulation and optimization of the energy-based blended quasicontinuum method
We formulate an energy-based atomistic-to-continuum coupling method based on blending the quasicontinuum method for the simulation of crystal defects. We utilize theoretical results from Van Koten and Luskin [32] and Ortner and Van Koten [24] to derive optimal choices of approximation parameters (blending function and finite element grid) for microcrack and di-vacancy test problems and confirm our analytical predictions in numerical tests
Collection and analysis of radar rainfall and satellite data for the Darwin TRMM experiment
The following subject areas are covered: video cloud camera (purpose, design, operation, data); special observing periods (SOP-2, SOP 2.5 - an extension of SOP-2); Garand algorithm; and warm rain
The 1999 Heineman Prize Address- Integrable models in statistical mechanics: The hidden field with unsolved problems
In the past 30 years there have been extensive discoveries in the theory of
integrable statistical mechanical models including the discovery of non-linear
differential equations for Ising model correlation functions, the theory of
random impurities, level crossing transitions in the chiral Potts model and the
use of Rogers-Ramanujan identities to generalize our concepts of Bose/Fermi
statistics. Each of these advances has led to the further discovery of major
unsolved problems of great mathematical and physical interest. I will here
discuss the mathematical advances, the physical insights and extraordinary lack
of visibility of this field of physics.Comment: Text of the 1999 Heineman Prize address given March 24 at the
Centenial Meeting of the American Physical Society in Atlanta 20 pages in
latex, references added and typos correcte
A statistical framework for testing functional categories in microarray data
Ready access to emerging databases of gene annotation and functional pathways
has shifted assessments of differential expression in DNA microarray studies
from single genes to groups of genes with shared biological function. This
paper takes a critical look at existing methods for assessing the differential
expression of a group of genes (functional category), and provides some
suggestions for improved performance. We begin by presenting a general
framework, in which the set of genes in a functional category is compared to
the complementary set of genes on the array. The framework includes tests for
overrepresentation of a category within a list of significant genes, and
methods that consider continuous measures of differential expression. Existing
tests are divided into two classes. Class 1 tests assume gene-specific measures
of differential expression are independent, despite overwhelming evidence of
positive correlation. Analytic and simulated results are presented that
demonstrate Class 1 tests are strongly anti-conservative in practice. Class 2
tests account for gene correlation, typically through array permutation that by
construction has proper Type I error control for the induced null. However,
both Class 1 and Class 2 tests use a null hypothesis that all genes have the
same degree of differential expression. We introduce a more sensible and
general (Class 3) null under which the profile of differential expression is
the same within the category and complement. Under this broader null, Class 2
tests are shown to be conservative. We propose standard bootstrap methods for
testing against the Class 3 null and demonstrate they provide valid Type I
error control and more power than array permutation in simulated datasets and
real microarray experiments.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS146 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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
Disconnected Elementary Band Representations, Fragile Topology, and Wilson Loops as Topological Indices: An Example on the Triangular Lattice
In this work, we examine the topological phases that can arise in triangular
lattices with disconnected elementary band representations. We show that,
although these phases may be "fragile" with respect to the addition of extra
bands, their topological properties are manifest in certain nontrivial
holonomies (Wilson loops) in the space of nontrivial bands. We introduce an
eigenvalue index for fragile topology, and we show how a nontrivial value of
this index manifests as the winding of a hexagonal Wilson loop; this remains
true even in the absence of time-reversal or sixfold rotational symmetry.
Additionally, when time-reversal and twofold rotational symmetry are present,
we show directly that there is a protected nontrivial winding in more
conventional Wilson loops. Crucially, we emphasize that these Wilson loops
cannot change without closing a gap to the nontrivial bands. By studying the
entanglement spectrum for the fragile bands, we comment on the relationship
between fragile topology and the "obstructed atomic limit" of B. Bradlyn et
al., Nature 547, 298--305 (2017). We conclude with some perspectives on
topological matter beyond the K-theory classification.Comment: 13 pages, 10 figures v2. accepted versio
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