1,203 research outputs found
A note on the integral equation for the Wilson loop in N = 2 D=4 superconformal Yang-Mills theory
We propose an alternative method to study the saddle point equation in the
strong coupling limit for the Wilson loop in D=4 super
Yang-Mills with an SU(N) gauge group and 2N hypermultiplets. This method is
based on an approximation of the integral equation kernel which allows to solve
the simplified problem exactly. To determine the accuracy of this
approximation, we compare our results to those obtained recently by Passerini
and Zarembo. Although less precise, this simpler approach provides an explicit
expression for the density of eigenvalues that is used to derive the planar
free energy.Comment: 12 pages, v2: section 2.5 (Free Energy) amended and reference added,
to appear in J. Phys.
Agronomic Value of Mixture of Perennial Rye-Grass Cultivars: Preliminary Results
Mixtures of grass and legume species are commonly used in sown grasslands. Mixtures have been shown to be favourable for stable production over cycles and years due to a succession of species over time (Mosimann & Charles, 1996 ; Nie et al, 2004). However, little is known whether the genetic variation in pure stands has an influence on the agronomic value and its variation over seasons
Boundary changing operators in the O(n) matrix model
We continue the study of boundary operators in the dense O(n) model on the
random lattice. The conformal dimension of boundary operators inserted between
two JS boundaries of different weight is derived from the matrix model
description. Our results are in agreement with the regular lattice findings. A
connection is made between the loop equations in the continuum limit and the
shift relations of boundary Liouville 3-points functions obtained from Boundary
Ground Ring approach.Comment: 31 pages, 4 figures, Introduction and Conclusion improve
Polarization tomography of metallic nanohole arrays
We report polarization tomography experiments on metallic nanohole arrays
with square and hexagonal symmetry. As a main result, we find that a fully
polarized input beam is partly depolarized after transmission through a
nanohole array. This loss of polarization coherence is found to be anisotropic,
i.e. it depends on the polarization state of the input beam. The depolarization
is ascribed to a combination of two factors: i) the nonlocal response of the
array due to surface plasmon propagation, ii) the non-plane wave nature of a
practical input beam.Comment: 4 pages, 3 figures, 1 table, submitted to PR
Should vascular wall F-18-FDG uptake be adjusted for the extent of atherosclerotic burden?
Vascular wall 18F-FDG uptake is often used as a surrogate marker of atherosclerotic plaque inflammation. A potential caveat is that vascular wall 18F-FDG uptake is higher simply because more atherosclerosis is present. To determine if the degree of inflammation is high or low relative to the extent of atherosclerosis, vascular wall 18F-FDG uptake may require statistical adjustment for a non-inflammatory marker reflecting the extent of atherosclerosis, e.g. calcification. Adjustments is probably needed if (1) vascular wall 18F-FDG uptake correlates sufficiently strongly with arterial calcification and (2) adjustment for extent of calcification affects determinants of vascular 18F-FDG uptake. This study addresses these questions. 18F-FDG PET/low-dose-CT scans of 99 patients were used. Cardiovascular risk factors were assessed and PET/CT scans were analysed for standardized 18F-FDG uptake values and calcification. ANOVA was used to establish the association between vascular 18F-FDG uptake and calcification. Multiple linear regression (with and without calcification as independent variable) was used to show whether determinants of vascular 18F-FDG uptake were affected by the degree of calcification. 18F-FDG uptake was related to increased calcification in the aortic arch, descending and abdominal aorta. However, 18F-FDG uptake showed considerable overlap between categories of calcification. Age and body mass index were main determinants of vascular 18F-FDG uptake. In multiple regression analyses, most standardized beta coefficients of these determinants were not affected by adjustment for the degree of calcification. Although vascular 18F-FDG uptake is related to total atherosclerotic burden, as reflected by vascular calcification, the association is weak and unlikely to affect the identification of determinants of atherosclerotic inflammation implicating no need for adjustment in future studies
Role of Grasslands and Grassland Management for Biogeochemical Cycles and Biodiversity. Setting up Long-Term Manipulation Experiments in France
Land use for grassland is recognised to have some beneficial effects for biodiversity and the environment: (i) regulation of the water cycle and protection of soils against erosion, (ii) accumulation of organic matter in soil and sequestration of atmospheric C, (iii) regulation of the N cycle and attenuation of the risk for N leaching, (iv) recycling of nutrients and improvement of soil quality, (v) improvement of biodiversity of vegetation, soil microbes and micro- and meso-fauna. All these effects depend upon the management of the grassland: cutting vs. grazing, stocking density, level of N inputs. Management decisions often result from short- term objectives, whereas the soil-vegetation interactions are long-term processes. Therefore, a steady state is usually not reached, which makes it difficult to determine the overall environmental effects of changes in land use and in grassland management
The role of geographical proximity in the establishment and development of science parks – evidence from Nanjing, China
The emergence of science parks is a relatively new phenomenon in China. Apart from the widely debated topics of university–industry linkages, collaboration among firms and spontaneous/policy-driven science parks, the development of science parks in China also has several distinguishing characteristics, such as their ambiguous linkage with urban expansion and their hierarchical structuring pattern. This paper attempts to discuss the motivation and efficiency of spatial proximity in science park development and to explore the role of universities in science parks, the function of science parks as a government project and a case study of location choice by on-site firms. The qualitative analysis, based on in-depth interviews with tenant firm managers and district-level government officers in Jiangning, Nanjing, is used as a basis for discussion
Colorectal neuroendocrine carcinomas and adenocarcinomas share oncogenic pathways. A clinico-pathologic study of 12 cases
OBJECTIVE:
Neuroendocrine carcinomas (NECs) are rare neoplasms with an increasing incidence. Oncogenetic pathways of colorectal NEC are still poorly understood, and no treatment standards are available for these rare tumors.
METHODS:
We analyzed retrospectively the clinical records and histology of 12 patients with colorectal NEC. KRAS and BRAF mutations were investigated after the dissection of exoendocrine and neuroendocrine components. ALK alterations and EML4-ALK transcripts were detected by in-situ hybridization and determination of fusion transcripts, respectively.
RESULTS:
At the time of diagnosis, the mean age of the patients was 60 years (40-79) and 10 patients had synchronous metastases. A transient response occurred in two patients and one patient treated with cisplatin-etoposide or fluoropyrimidine-oxaliplatin, respectively. Tumor progression-related death occurred in 11 of 12 patients. Ten tumors contained an exocrine component, accounting for 5-70% of the tumor, and the other two contained an amphicrine component. BRAF/KRAS mutations were found in six of 10 tumors, corresponding to BRAF(V600E) (n=2) or KRAS(G12D) (n=2), KRAS(G12V) or KRAS(G13D). DNA was obtained from both exocrine and endocrine components in seven cases, and the BRAF/KRAS status was identical in all cases. Split of the ALK locus was detected in a minority of tumor cells in two of eight cases, but EML4-ALK transcripts were absent.
CONCLUSION:
The association of an exocrine component in all cases and the similar profile of BRAF/KRAS mutations indicate that colorectal NEC may correspond to a high-grade transformation of colorectal carcinoma. New chemotherapy regimens using targeted therapies should be assessed in these tumors
Influence of Molecular Status on Recurrence Site in Patients Treated for a Stage III Colon Cancer: a Post Hoc Analysis of the PETACC-8 Trial
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