234 research outputs found
Tadpole Method and Supersymmetric O(N) Sigma Model
We examine the phase structures of the supersymmetric O(N) sigma model in two
and three dimensions by using the tadpole method. Using this simple method, the
calculation is largely simplified and the characteristics of this theory become
clear. We also examine the problem of the fictitious negative energy state.Comment: Plain Latex(12pages), No figur
Asymptotic distinguishability measures for shift-invariant quasi-free states of fermionic lattice systems
We apply the recent results of F. Hiai, M. Mosonyi and T. Ogawa
[arXiv:0707.2020, to appear in J. Math. Phys.] to the asymptotic hypothesis
testing problem of locally faithful shift-invariant quasi-free states on a CAR
algebra. We use a multivariate extension of Szego's theorem to show the
existence of the mean Chernoff and Hoeffding bounds and the mean relative
entropy, and show that these quantities arise as the optimal error exponents in
suitable settings.Comment: Results extended to higher dimensional lattices, title changed.
Submitted versio
X-ray absorption spectroscopy elucidates the impact of structural disorder on electron mobility in amorphous zinc-tin-oxide thin films
We investigate the correlation between the atomic structures of amorphous zinc-tin-oxide (a-ZTO) thin films grown by atomic layer deposition (ALD) and their electronic transport properties. We perform synchrotron-based X-ray absorption spectroscopy at the K-edges of Zn and Sn with varying [Zn]/[Sn] compositions in a-ZTO thin films. In extended X-ray absorption fine structure (EXAFS) measurements, signal attenuation from higher-order shells confirms the amorphous structure of a-ZTO thin films. Both quantitative EXAFS modeling and X-ray absorption near edge spectroscopy (XANES) reveal that structural disorder around Zn atoms increases with increasing [Sn]. Field- and Hall-effect mobilities are observed to decrease with increasing structural disorder around Zn atoms, suggesting that the degradation in electron mobility may be correlated with structural changes.United States. Office of Naval Research (ONR N00014-10-1-0937)National Science Foundation (U.S.) (Award CBET-1032955)National Science Foundation (U.S.) (CAREER Award ECCS-1150878
Gravitational Waves around a Naked Singularity -- Odd-Parity Perturbation of Lemaitre-Tolman-Bondi Space-Time --
The motion of a spherical dust cloud is described by the
Lemaitre-Tolman-Bondi solution and is completely specified by initial values of
distributions of the rest mass density and specific energy of the dust fluid.
From generic initial conditions of this spherically symmetric collapse, there
appears a naked singularity at the symmetric center in the course of the
gravitational collapse of the dust cloud. So this might be a counter example to
the cosmic censorship hypothesis. To investigate the genericity of this
example, we examine the stability of the `nakedness' of this singularity
against odd-parity modes of non-spherical linear perturbations for the metric,
i.e., linear gravitational waves. We find that the perturbations do not diverge
but are well-behaved even in the neighborhood of the central naked singularity.
This means that the naked singularity formation process is marginally stable
against the odd-parity modes of linear gravitational waves.Comment: 19 pages, 12 figures, to be published in Physical Review
Computing gravitational waves from slightly nonspherical stellar collapse to black hole: Odd-parity perturbation
Nonspherical stellar collapse to a black hole is one of the most promising
gravitational wave sources for gravitational wave detectors. We numerically
study gravitational waves from a slightly nonspherical stellar collapse to a
black hole in linearized Einstein theory. We adopt a spherically collapsing
star as the zeroth-order solution and gravitational waves are computed using
perturbation theory on the spherical background. In this paper we focus on the
perturbation of odd-parity modes. Using the polytropic equations of state with
polytropic indices and 3, we qualitatively study gravitational waves
emitted during the collapse of neutron stars and supermassive stars to black
holes from a marginally stable equilibrium configuration. Since the matter
perturbation profiles can be chosen arbitrarily, we provide a few types for
them. For , the gravitational waveforms are mainly characterized by a
black hole quasinormal mode ringing, irrespective of perturbation profiles
given initially. However, for , the waveforms depend strongly on the
initial perturbation profiles. In other words, the gravitational waveforms
strongly depend on the stellar configuration and, in turn, on the ad hoc choice
of the functional form of the perturbation in the case of supermassive stars.Comment: 31 pages, accepted for publication in Phys. Rev. D, typos and minor
errors correcte
Acute Pancreatitis due to pH-Dependent Mesalazine That Occurred in the Course of Ulcerative Colitis
We report the case of a 26-year-old male who presented with acute pancreatitis during the course of treatment for pancolitic ulcerative colitis (UC) with a time-dependent mesalazine formulation, prednisolone and azathioprine (AZA). Despite a review of his clinical history and various tests, the cause of pancreatitis could not be determined. Since drug-induced pancreatitis was considered possible, administration of the time-dependent mesalazine preparation and AZA was discontinued, and conservative treatment for acute pancreatitis was performed. The pancreatitis promptly improved with these treatments, but drug lymphocyte stimulation test (DLST) for both the time-dependent mesalazine formulation and AZA was negative. A pH-dependent mesalazine formulation was given for maintenance therapy of UC. Subsequently, as the pancreatitis relapsed, drug-induced pancreatitis was strongly suspected. Administration of mesalazine was discontinued, and pancreatitis was smoothly in remission by conservative treatment. According to the positive DLST result for the pH-dependent mesalazine formulation and the clinical course, a diagnosis of pH-dependent mesalazine-induced pancreatitis due to this formulation was made. During the clinical course of UC, occurrence of drug-induced pancreatitis must always be considered
Intrinsic chemical and structural inhomogeneity in lightly doped La(1-x)Sr(x)MnO(3)
X-ray absorption fine structure measurements of the Sr and La K edges of the
solid solution La(1-x)Sr(x)MnO(3) reveal a consistent deviation from a random
distribution of Sr at the La/Sr sites for x~0.3. Local structural disorder on
the cation sublattice in the low-x samples is also observed to differ in the
vicinity of the La-rich and Sr-rich clusters. The local clustering and
structural disorder establish an intrinsic chemical as well as structural
inhomogeneity on the nanometer scale, which may provide a mechanism for the
nucleation of magnetoelectronic phase separation.Comment: PDF with 4 embedded figure
Toward A Brain-Based Theory of Beauty
We wanted to learn whether activity in the same area(s) of the brain correlate with the experience of beauty derived from different sources. 21 subjects took part in a brain-scanning experiment using functional magnetic resonance imaging. Prior to the experiment, they viewed pictures of paintings and listened to musical excerpts, both of which they rated on a scale of 1-9, with 9 being the most beautiful. This allowed us to select three sets of stimuli-beautiful, indifferent and ugly-which subjects viewed and heard in the scanner, and rated at the end of each presentation. The results of a conjunction analysis of brain activity showed that, of the several areas that were active with each type of stimulus, only one cortical area, located in the medial orbito-frontal cortex (mOFC), was active during the experience of musical and visual beauty, with the activity produced by the experience of beauty derived from either source overlapping almost completely within it. The strength of activation in this part of the mOFC was proportional to the strength of the declared intensity of the experience of beauty. We conclude that, as far as activity in the brain is concerned, there is a faculty of beauty that is not dependent on the modality through which it is conveyed but which can be activated by at least two sources-musical and visual-and probably by other sources as well. This has led us to formulate a brain-based theory of beauty
Interpopulation variation in female remating is attributable to female and male effects in Callosobruchus chinensis
The evolution of female multiple mating is best understood by consideration of male and female reproductive perspectives. Females should usually be selected to remate at their optimum frequencies whereas males should be selected to manipulate female remating to their advantage. Female remating behavior may therefore be changed by variation of male and female traits. In this study, our objective was to separate the effects of female and male strains on female remating for the adzuki bean beetle, Callosobruchus chinensis, for which there is interstrain variation in female remating frequency. We found that interstrain variation in female remating is primarily attributable to female traits, suggesting genetic variation in female receptivity to remating in C. chinensis. Some interstrain variation in female remating propensity was attributable to an interaction between female and male strains, however, with the males of some strains being good at inducing nonreceptivity in females from one high-remating strain whereas others were good at inducing copulation in nonvirgin females from the high-remating strain. There is, therefore, interstrain variation in male ability to deter females from remating and in male ability to mate successfully with nonvirgin females. These results suggest that mating traits have evolved along different trajectories in different strains of C. chinensis.</p
Focal dose escalation using FDG-PET-guided intensity-modulated radiation therapy boost for postoperative local recurrent rectal cancer: a planning study with comparison of DVH and NTCP
<p>Abstract</p> <p>Background</p> <p>To evaluate the safety of focal dose escalation to regions with standardized uptake value (SUV) >2.0 using intensity-modulated radiation therapy (IMRT) by comparison of radiotherapy plans using dose-volume histograms (DVHs) and normal tissue complication probability (NTCP) for postoperative local recurrent rectal cancer</p> <p>Methods</p> <p>First, we performed conventional radiotherapy with 40 Gy/20 fr. (CRT 40 Gy) for 12 patients with postoperative local recurrent rectal cancer, and then we performed FDG-PET/CT radiotherapy planning for those patients. We defined the regions with SUV > 2.0 as biological target volume (BTV) and made three boost plans for each patient: 1) CRT boost plan, 2) IMRT without dose-painting boost plan, and 3) IMRT with dose-painting boost plan. The total boost dose was 20 Gy. In IMRT with dose-painting boost plan, we increased the dose for BTV+5 mm by 30% of the prescribed dose. We added CRT boost plan to CRT 40 Gy (<it>summed plan 1</it>), IMRT without dose-painting boost plan to CRT 40 Gy (<it>summed plan 2</it>) and IMRT with dose-painting boost plan to CRT 40 Gy (<it>summed plan 3</it>), and we compared those plans using DVHs and NTCP.</p> <p>Results</p> <p>D<sub>mean </sub>of PTV-PET and that of PTV-CT were 26.5 Gy and 21.3 Gy, respectively. V<sub>50 </sub>of small bowel PRV in <it>summed plan 1 </it>was significantly higher than those in other plans ((<it>summed plan 1 </it>vs. <it>summed plan 2 </it>vs. <it>summed plan 3</it>: 47.11 ± 45.33 cm<sup>3 </sup>vs. 40.63 ± 39.13 cm<sup>3 </sup>vs. 41.25 ± 39.96 cm<sup>3</sup>(p < 0.01, respectively)). There were no significant differences in V<sub>30</sub>, V<sub>40</sub>, V<sub>60</sub>, D<sub>mean </sub>or NTCP of small bowel PRV.</p> <p>Conclusions</p> <p>FDG-PET-guided IMRT can facilitate focal dose-escalation to regions with SUV above 2.0 for postoperative local recurrent rectal cancer.</p
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