5,095 research outputs found
Open-closed field algebras
We introduce the notions of open-closed field algebra and open-closed field
algebra over a vertex operator algebra V. In the case that V satisfies certain
finiteness and reductivity conditions, we show that an open-closed field
algebra over V canonically gives an algebra over a \C-extension of the
Swiss-cheese partial operad. We also give a tensor categorical formulation and
categorical constructions of open-closed field algebras over V.Comment: 55 pages, largely revised, an old subsection is deleted, a few
references are adde
Fusion rules and singular vectors of the osp(1|2) current algebra
The fusion of Verma modules of the osp(1|2) current algebra is studied. In
the framework of an isotopic formalism, the singular vector decoupling
conditions are analyzed. The fusion rules corresponding to the admissible
representations of the osp(1|2) algebra are determined. A relation between the
characters of these last representations and those corresponding to the minimal
superconformal models is found. A series of equations that relate the
descendants of the highest weight vectors resulting from a fusion of Verma
modules are obtained. Solving these equations the singular vectors of the
theory can be determined.Comment: 63 pages, phyzz
How Do Firms Respond to Political Tensions? The Heterogeneity of the Dalai Lama Effect on Trade
Little is known about the firm-level dynamics behind trade responses to political tensions. This article reinvestigates variation in the travel pattern of the 14th Dalai Lama to study how political tensions affect trading decisions of Chinese importers. Using monthly trade data from China Customs covering imports of machinery and transport equipment from 173 countries over the 2000-2006 period, our empirical results show a significant reduction of imports in response to foreign government membersâ meetings with the Dalai Lama. In line with the idea that Chinese importers face a trade-off between bearing costs from suboptimal trade transactions and costs from not accommodating the government, this âDalai Lama Effectâ operates at the intensive margin, i.e., via a decrease in the import volume per importer. Examining differential effects across types of firm ownership, we find that the observed effect is driven by state-owned enterprises (and foreign-invested firms) and not by private companies. Moreover, while direct importers temporarily reduce their trade with Dalai Lama-receiving countries, there is some evidence that trade intermediaries even benefit. Overall, we
find the effects to be much more short-lived than previously thought
Loop Corrections and Naturalness in a Chiral Effective Field Theory
The loop expansion is applied to a chiral effective hadronic lagrangian; with
the techniques of Infrared Regularization, it is possible to separate out the
short-range contributions and to write them as local products of fields that
are already present in our lagrangian. (The appropriate field variables must be
re-defined at each order in loops.) The corresponding parameters implicitly
include short-range effects to all orders in the interaction, so these effects
need not be calculated explicitly. The remaining (long-range) contributions
that must be calculated are nonlocal and resemble those in conventional
nuclear-structure calculations. Nonlinear isoscalar scalar and
vector meson interactions are included, which incorporate
many-nucleon forces and nucleon substructure. Calculations are carried out at
the two-loop level to illustrate these techniques at finite nuclear densities
and to verify that the coupling parameters remain natural when fitted to the
empirical properties of equilibrium nuclear matter. Contributions from the
tensor coupling are also discussed.Comment: 22 pages, 6 figure
Structure constants for the osp(1|2) current algebra
We study the free field realization of the two-dimensional osp(1|2) current
algebra. We consider the case in which the level of the affine osp(1|2)
symmetry is a positive integer. Using the Coulomb gas technique we obtain
integral representations for the conformal blocks of the model. In particular,
from the behaviour of the four-point function, we extract the structure
constants for the product of two arbitrary primary operators of the theory.
From this result we derive the fusion rules of the osp(1|2) conformal field
theory and we explore the connections between the osp(1|2) affine symmetry and
the N=1 superconformal field theories.Comment: 64 pages, phyzzx, no figure
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Nut consumption and risk of pancreatic cancer in women
Background: Increasing nut intake has been associated with reduced risk of diabetes mellitus, which is a risk factor for pancreatic cancer. Methods: We prospectively followed 75 680 women in the Nurses' Health Study, and examined the association between nut consumption and pancreatic cancer risk. Participants with a previous history of cancer were excluded. Nut consumption was assessed at baseline and updated every 2 to 4 years. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models. Results: We documented 466 incident cases of pancreatic cancer. After adjusting for age, height, smoking, physical activity, and total energy intake, women who consumed a 28-g (1 oz) serving size of nuts â©Ÿ2 times per week experienced a significantly lower risk of pancreatic cancer (RR, 0.65; 95% CI, 0.47â0.92; P for trend=0.007) when compared with those who largely abstained from nuts. The results did not appreciably change after further adjustment for body mass index (BMI) and history of diabetes mellitus (RR, 0.68; 95% CI, 0.48â0.95; P for trend=0.01). The inverse association persisted within strata defined by BMI, physical activity, smoking, and intakes of red meat, fruits, and vegetables. Conclusion: Frequent nut consumption is inversely associated with risk of pancreatic cancer in this large prospective cohort of women, independent of other potential risk factors for pancreatic cancer
Infrared Observations of the Candidate LBV 1806-20 & Nearby Cluster Stars
We report near-infrared photometry, spectroscopy, and speckle imaging of the
hot, luminous star we identify as candidate LBV 1806-20. We also present
photometry and spectroscopy of 3 nearby stars, which are members of the same
star cluster containing LBV 1806-20 and SGR 1806-20. The spectroscopy and
photometry show that LBV 1806-20 is similar in many respects to the luminous
``Pistol Star'', albeit with some important differences. They also provide
estimates of the effective temperature and reddening of LBV 1806-20, and
confirm distance estimates, leading to a best estimate for the luminosity of
this star of . The nearby cluster stars have
spectral types and inferred absolute magnitudes which confirm the distance (and
thus luminosity) estimate for LBV 1806-20. If we drop kinematic measurements of
the distance ( kpc), we have a lower limit on the distance
of kpc, and on the luminosity of , based on
the cluster stars. If we drop both the kinematic and cluster star indicators
for distance, an ammonia absorption feature sets yet another lower limit to the
distance of kpc, with a corresponding luminosity estimate of for the candidate LBV 1806-20. Furthermore, based on very high
angular-resolution speckle images, we determine that LBV 1806-20 is not a
cluster of stars, but is rather a single star or binary system. Simple
arguments based on the Eddington luminosity lead to an estimate of the total
mass of LBV 1806-20 (single or binary) exceeding . We discuss
the possible uncertainties in these results, and their implications for the
star formation history of this cluster.Comment: 36 pages, including 8 figures (Figures 1 and 7 in JPG format due to
space); Accepted for publication in Ap
Effects of point defects on the phase diagram of vortex states in high-Tc superconductors in B//c axis
The phase diagram for the vortex states of high- superconductors
with point defects in axis is drawn by large-scale Monte
Carlo simulations. The vortex slush (VS) phase is found between the vortex
glass (VG) and vortex liquid (VL) phases. The first-order transition between
this novel normal phase and the VL phase is characterized by a sharp jump of
the density of dislocations. The first-order transition between the Bragg glass
(BG) and VG or VS phases is also clarified. These two transitions are compared
with the melting transition between the BG and VL phases.Comment: 4 pages, 9 eps figures (included in text), uses revtex.sty, overall
changes with several additional data points, though conclusion is unchange
A HfS -based photoelectronic synaptic transistor with tunable synaptic plasticity for emotional memory
Dietary patterns during high school and risk of colorectal adenoma in a cohort of middle-aged women
Adolescent diet may be etiologically relevant for later risk of colorectal adenoma, a precursor of colorectal cancer. We aimed to examine associations between adolescent dietary patterns (derived using factor analysis) and risk of colorectal adenoma in middle adulthood. We analyzed data from 17,221 women participating in the Nurses' Health Study II, who had completed a validated high school (HS) food frequency questionnaire in 1998 when they were 34-51 years old, and had subsequently undergone at least one lower bowel endoscopy. Between 1998 and 2007, 1,299 women were diagnosed with at least one colorectal adenoma. In multivariable models adjusted for adult dietary patterns, a higher "prudent" pattern during HS, characterized by high consumption of vegetables, fruit and fish was associated with a statistically significantly lower risk of rectal (odds ratio [OR] highest vs. lowest quintile, 0.45, 95% CI 0.27-0.75, p-trend=0.005), but not colon adenomas. A higher "Western" pattern during HS, characterized by high consumption of desserts and sweets, snack foods and red and processed meat, was significantly associated with rectal (OR 1.78, 95% CI 1.12-2.85, p-trend=0.005) and advanced (OR 1.58, 95% CI 1.07-2.33, p-trend=0.08), but not associated with colon or non-advanced adenomas. This study suggests that overall eating patterns during high school may influence later risk of rectal and advanced adenoma, independent of adult diet. Our results support the hypothesis that diet during early life may influence colorectal carcinogenesis
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