10,200 research outputs found
N = 2 conformal field theories from M2-branes at conifold singularities
We make some comments on the derivation of N=2 super-conformal field theories
with smooth gauge group from M2-branes placed at conifold singularities, giving
a detailed prescription for two specific examples: the singular cones over the
Q^{111} and M^{110} manifolds.Comment: 1+11 pages, LaTeX2e file, clarified some points and added some
reference
Evaluation of the Cost and Effectiveness of Direct Nutrition Education to Low-Income Audiences in Iowa: EFNEP and SNAP-Ed graduates practicing Optimal Nutritional Behaviors (ONB)
The Expanded Food and Nutrition Education Program (EFNEP) and the Family Nutrition Program (FNP) (the Supplemental Nutrition Assistance Program-Education, or SNAP-Ed in Iowa) are community outreach programs in Iowa designed to help teens and adults who have limited income and are parenting acquire the knowledge, skills, attitudes, and practices to improve total family diet and nutritional well-being. This study uses current information on Iowa’s EFNEP and FNP today to evaluate the costs and benefits of the two related programs and provides updated information to a study conducted in Iowa from 1998 to 2000.
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Model study for the nonequlibrium magnetic domain structure during the growth of nanostructured ultrathin films
The nonequilibrium magnetic domain structure of growing ultrathin
ferromagnetic films with a realistic atomic structure is studied as a function
of coverage and temperature. We apply a kinetic Monte Carlo method to a
micromagnetic model describing the transition from superparamagnetic islands at
low coverages to a closed ferromagnetic film. The magnetic relaxation and the
island growth happen simultaneously. Near the percolation threshold a
metastable magnetic domain structure is obtained with an average domain area
ranging between the area of individual magnetic islands and the area of the
large domains observed for thicker ferromagnetic films. We conclude that this
micro-domain structure is controlled and stabilized by the nonuniform atomic
nanostructure of the ultrathin film, causing a random interaction between
magnetic islands with varying sizes and shapes. The average domain area and
domain roughness are determined. A maximum of the domain area and a minimum of
the domain roughness are obtained as a function of the temperature.Comment: 19 pages, 4 Postscript figures; to be published in J. Magn. Magn.
Mater., accepted (2001); completely revised manuscrip
Lactobacillus reuteri inhibition of Enteropathogenic Escherichia coli adherence to human intestinal epithelium
Enteropathogenic Escherichia coli (EPEC) is a major cause of diarrheal infant death in developing countries, and probiotic bacteria have been shown to provide health benefits in gastrointestinal infections. In this study, we have investigated the influence of the gut symbiont Lactobacillus reuteri on EPEC adherence to the human intestinal epithelium. Different host cell model systems including non-mucus-producing HT-29 and mucus-producing LS174T intestinal epithelial cell lines as well as human small intestinal biopsies were used. Adherence of L. reuteri to HT-29 cells was strain-specific, and the mucus-binding proteins CmbA and MUB increased binding to both HT-29 and LS174T cells. L. reuteri ATCC PTA 6475 and ATCC 53608 significantly inhibited EPEC binding to HT-29 but not LS174T cells. While pre-incubation of LS174T cells with ATCC PTA 6475 did not affect EPEC attaching/effacing (A/E) lesion formation, it increased the size of EPEC microcolonies. ATCC PTA 6475 and ATCC 53608 binding to the mucus layer resulted in decreased EPEC adherence to small intestinal biopsy epithelium. Our findings show that L. reuteri reduction of EPEC adhesion is strain-specific and has the potential to target either the epithelium or the mucus layer, providing further rationale for the selection of probiotic strains
Foreign investors’ trading behaviors around merger and acquisition announcements: Evidence from Korea
© 2019 Elsevier Inc. This study examines foreign investors’ trading behaviors around merger and acquisition (M&A) announcements in the Korean stock market (both KOSPI and KOSDAQ markets). We find evidence that foreign investors are more likely to buy target stocks with larger wealth effects on the KOSPI market. In contrast, our results reveal that both foreign and domestic investors are not able to identify target stocks with larger wealth effects on the KOSDAQ market. Further, we find that in response to M&A announcements, only foreign investors can find target stocks with greater subsequent returns on the KOSDAQ market, but not on the KOSPI market
Theory of the NO+CO surface reaction model
We derive a pair approximation (PA) for the NO+CO model with instantaneous
reactions. For both the triangular and square lattices, the PA, derived here
using a simpler approach, yields a phase diagram with an active state for
CO-fractions y in the interval y_1 < y < y_2, with a continuous (discontinuous)
phase transition to a poisoned state at y_1 (y_2). This is in qualitative
agreement with simulation for the triangular lattice, where our theory gives a
rather accurate prediction for y_2. To obtain the correct phase diagram for the
square lattice, i.e., no active state, we reformulate the PA using sublattices.
The (formerly) active regime is then replaced by a poisoned state with broken
symmetry (unequal sub- lattice coverages), as observed recently by Kortluke et
al. [Chem. Phys. Lett. 275, 85 (1997)]. In contrast with their approach, in
which the active state persists, although reduced in extent, we report here the
first qualitatively correct theory of the NO+CO model on the square lattice.
Surface diffusion of nitrogen can lead to an active state in this case. In one
dimension, the PA predicts that diffusion is required for the existence of an
active state.Comment: 15 pages, 9 figure
Orbital Magnetism in the Ballistic Regime: Geometrical Effects
We present a general semiclassical theory of the orbital magnetic response of
noninteracting electrons confined in two-dimensional potentials. We calculate
the magnetic susceptibility of singly-connected and the persistent currents of
multiply-connected geometries. We concentrate on the geometric effects by
studying confinement by perfect (disorder free) potentials stressing the
importance of the underlying classical dynamics. We demonstrate that in a
constrained geometry the standard Landau diamagnetic response is always
present, but is dominated by finite-size corrections of a quasi-random sign
which may be orders of magnitude larger. These corrections are very sensitive
to the nature of the classical dynamics. Systems which are integrable at zero
magnetic field exhibit larger magnetic response than those which are chaotic.
This difference arises from the large oscillations of the density of states in
integrable systems due to the existence of families of periodic orbits. The
connection between quantum and classical behavior naturally arises from the use
of semiclassical expansions. This key tool becomes particularly simple and
insightful at finite temperature, where only short classical trajectories need
to be kept in the expansion. In addition to the general theory for integrable
systems, we analyze in detail a few typical examples of experimental relevance:
circles, rings and square billiards. In the latter, extensive numerical
calculations are used as a check for the success of the semiclassical analysis.
We study the weak-field regime where classical trajectories remain essentially
unaffected, the intermediate field regime where we identify new oscillations
characteristic for ballistic mesoscopic structures, and the high-field regime
where the typical de Haas-van Alphen oscillations exhibit finite-size
corrections. We address the comparison with experimental data obtained in
high-mobility semiconductor microstructures discussing the differences between
individual and ensemble measurements, and the applicability of the present
model.Comment: 88 pages, 15 Postscript figures, 3 further figures upon request, to
appear in Physics Reports 199
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