3,351 research outputs found
Local Hall effect in hybrid ferromagnetic/semiconductor devices
We have investigated the magnetoresistance of ferromagnet-semiconductor
devices in an InAs two-dimensional electron gas system in which the magnetic
field has a sinusoidal profile. The magnetoresistance of our device is large.
The longitudinal resistance has an additional contribution which is odd in
applied magnetic field. It becomes even negative at low temperature where the
transport is ballistic. Based on the numerical analysis, we confirmed that our
data can be explained in terms of the local Hall effect due to the profile of
negative and positive field regions. This device may be useful for future
spintronic applications.Comment: 4 pages with 4 fugures. Accepted for publication in Applied Physics
Letter
Symplectic embedding and Hamilton-Jacobi analysis of Proca model
Following the symplectic approach we show how to embed the Abelian Proca
model into a first-class system by extending the configuration space to include
an additional pair of scalar fields, and compare it with the improved Dirac
scheme. We obtain in this way the desired Wess-Zumino and gauge fixing terms of
BRST invariant Lagrangian. Furthermore, the integrability properties of the
second-class system described by the Abelian Proca model are investigated using
the Hamilton-Jacobi formalism, where we construct the closed Lie algebra by
introducing operators associated with the generalized Poisson brackets.Comment: 24 page
Nearest pattern interaction and global pattern formation
We studied the effect of nearest pattern interaction on a globally pattern
formation in a 2-dimensional space, where patterns are to grow initially from a
noise in the presence of periodic supply of energy. Although our approach is
general, we found that this study is relevant in particular to the pattern
formation on a periodically vibrated granular layer, as it gives a unified
perspective of the experimentally observed pattern dynamics such as oscillon
and stripe formations, skew-varicose and crossroll instabilities, and also a
kink formation and decoration
Diffeomorphic random sampling using optimal information transport
In this article we explore an algorithm for diffeomorphic random sampling of
nonuniform probability distributions on Riemannian manifolds. The algorithm is
based on optimal information transport (OIT)---an analogue of optimal mass
transport (OMT). Our framework uses the deep geometric connections between the
Fisher-Rao metric on the space of probability densities and the right-invariant
information metric on the group of diffeomorphisms. The resulting sampling
algorithm is a promising alternative to OMT, in particular as our formulation
is semi-explicit, free of the nonlinear Monge--Ampere equation. Compared to
Markov Chain Monte Carlo methods, we expect our algorithm to stand up well when
a large number of samples from a low dimensional nonuniform distribution is
needed.Comment: 8 pages, 3 figure
Surgical anatomy of the uncinate process and transverse foramen determined by computer tomography
Study Design Computed tomography–based cohort study. Objective Although there are publications concerning the relationship between the vertebral artery and uncinate process, there is no practical guide detailing the dimensions of this region to use during decompression of the intervertebral foramen. The purpose of this study is to determine the anatomic parameters that can be used as a guide for thorough decompression of the intervertebral foramen. Methods Fifty-one patients with three-dimensional computed tomography scans of the cervical spine from 2003 to 2012 were included. On axial views, we measured the distance from the midline to the medial and lateral cortices of the pedicle bilaterally from C3 to C7. On coronal reconstructed views, we measured the minimum height of the uncinate process from the cranial cortex of the pedicle adjacent to the posterior cortex of vertebral body and the maximal height of the uncinate process from the cranial cortex of the pedicle at the midportion of the vertebral body bilaterally from C3 to C7. Results The mean distances from midline to the medial and lateral cortices of the pedicle were 10.1 ± 1.3 mm and 13.9 ± 1.5 mm, respectively. The mean minimum height of the uncinate process from the cranial cortex of the pedicle was 4.6 ± 1.6 mm and the mean maximal height was 6.1 ± 1.7 mm. Conclusions Our results suggest that in most cases, one can thoroughly decompress the intervertebral foramen by removing the uncinate out to 13 mm laterally from the midline and 4 mm above the pedicle without violating the transverse foramen
Design, Analysis and Empirical Researches for Solar Heat Collecting System based on Flat Mirrors Combination
There has been a dramatic increase of research on energy production using solar energy. This research aims to examine development of concentrating solar collector that is related to mid-high solar energy field. Although the use of dish type solar thermal system has been common in the existing high-efficiency collector technology, several problems have been raised. In order to solve these issues, the frame has been designed as flat plate type with Fresnel lens and the structural stability has been proved by analysis. Furthermore, the experiment that checks collectorrsquos temperature has been performed for the correct works of the stirling engine
Radiative Neutron-Proton Capture in Effective Chiral Lagrangians
We calculate the cross-section for the thermal
process in chiral perturbation theory to next-to-next-to-leading order using
heavy-fermion formalism. The exchange current correction is found to be
in amplitude and the chiral perturbation at one-loop order
gives the cross section \sigma_{th}^{np}=(334\pm 2)\ {\mbox mb} which is in
agreement with the experimental value (334.2\pm 0.5)\ {\mbox mb}. Together
with the axial charge transitions, this provides a strong support for the power
of chiral Lagrangians for nuclear physics.Comment: 9 pages, revtex, uses epsfig.sty, 2 uuencoded figure
Variation in Periodontal Diagnosis and Treatment Planning Among Clinical Instructors
Consistency in clinical decision making may be necessary for reliable assessment of student performance and teaching effectiveness, yet little has been done to examine variation in periodontal diagnosis and treatment planning among dental school faculty. The purpose of this investigation was to examine variation among faculty in diagnosis and management of common periodontal diseases. Twenty-seven clinical instructors (periodontists, general dentists, dental hygienists, and first- and second-year periodontal graduate students) reviewed three web-based cases and answered a brief questionnaire focusing on radiographic interpretation, periodontal diagnosis, and treatment planning. Response rates for the three cases ranged from 62 percent to 70 percent. Clinical instructors’ rating of percent bone loss in the majority of cases varied between three descriptive categories for the same tooth. Greater consistency in periodontal diagnosis was noted within the graduate student group as compared to periodontal and dental hygiene faculty groups. Diagnoses offered for one of the three patients varied between gingivitis and chronic and aggressive periodontitis. Six to nineteen different treatment plans (many with subtle differences) were submitted for each of the three cases. Inter-rater variation was qualitatively more prevalent than intra-rater variation. To our knowledge, this is the first study to document substantial variation among instructors in radiographic interpretation, diagnosis, and treatment planning for common periodontal diseases. Qualitative judgments speculating on the impact of variability among dental school faculty on student performance and patient care can be made but as yet remain unknown. Consistent use of accepted practice guidelines and greater consensus-building opportunities may decrease variation among faculty and enhance dental education
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