41,861 research outputs found
Moving Stationary State of Exciton-Phonon Condensate in Cu2O
We explore a simple theoretical model to describe the properties of Bose
condensed para-excitons in Cu2O. Taking into account the exciton-phonon
interaction and introducing a coherent phonon part of the moving condensate, we
derive the dynamic equations for the exciton-phonon condensate. Within the Bose
approximation for excitons, we discuss the conditions for the moving
inhomogeneous condensate to appear in the crystal. We calculate the condensate
wave function and energy and a collective excitation spectrum in the
semiclassical approximation. The stability conditions of the moving condensate
are analyzed by use of Landau arguments, and two critical velocities appear in
the theory. Finally, we apply our model to describe the recently observed
interference between two coherent exciton-phonon packets in Cu2O.Comment: 20 pages (LaTeX), one figure (.ps) incorporated by epsf. Submitted to
Phys. Stat. Sol (B
Linkage in cattle between the major histocompatibility complex (BoLA) and the M blood group system
Relationships between the bovine Major Histocompatibility Complex (MHC) and 11 blood group systems were examined using genetic information obtained from 58 families with doubly-heterozygous parents. The data were analyzed by the lod-score method: Close to moderate linkage between the cattle MHC (BoLA complex) and 10 blood group loci, A, B, C, F, J, L, S, Z, R’ and T’ was excluded. Evidence for a close linkage between BoLA and the M blood group system is presented and a recombination frequency of 0.04 was estimated. The possibility of a linkage disequilibrium in the BoLA-M system chromosomal region is suggested.Les relations entre le Complexe Majeur d’Histocompatibilité (CMH) des bovins et les 11 systèmes de groupes sanguins ont été examinées en utilisant l’information génétique recueillie dans 58 familles de parents double-hétérozygotes. Les données ont été analysées par la méthode du lod-score. Toute liaison génétique étroite ou modérée entre le CMH bovin (complexe BOLA) et 10 des loci de groupes sanguins : A, B, C, F, J, L, S, Z, R’ et T’ est exclue. L’existence d’une liaison génétique étroite entre BoLA et le système M de groupes sanguins est établie, avec une fréquence de recombinaison estimée à 0,04. La possibilité d’un déséquilibre de liaison au sein de la région chromosomique BoLA-système M est suggérée
Error Corrective Boosting for Learning Fully Convolutional Networks with Limited Data
Training deep fully convolutional neural networks (F-CNNs) for semantic image
segmentation requires access to abundant labeled data. While large datasets of
unlabeled image data are available in medical applications, access to manually
labeled data is very limited. We propose to automatically create auxiliary
labels on initially unlabeled data with existing tools and to use them for
pre-training. For the subsequent fine-tuning of the network with manually
labeled data, we introduce error corrective boosting (ECB), which emphasizes
parameter updates on classes with lower accuracy. Furthermore, we introduce
SkipDeconv-Net (SD-Net), a new F-CNN architecture for brain segmentation that
combines skip connections with the unpooling strategy for upsampling. The
SD-Net addresses challenges of severe class imbalance and errors along
boundaries. With application to whole-brain MRI T1 scan segmentation, we
generate auxiliary labels on a large dataset with FreeSurfer and fine-tune on
two datasets with manual annotations. Our results show that the inclusion of
auxiliary labels and ECB yields significant improvements. SD-Net segments a 3D
scan in 7 secs in comparison to 30 hours for the closest multi-atlas
segmentation method, while reaching similar performance. It also outperforms
the latest state-of-the-art F-CNN models.Comment: Accepted at MICCAI 201
The role of cow dung and kitchen manure composts and their non-aerated compost teas in reducing the incidence of foliar diseases of Lycopersicon esculentum (Mill)
Compost teas are fermented watery extracts of composted materials used for their beneficial effect on plants. A study was conducted in the field to compare the efficacy of cow dung and kitchen manure composts and their derived non-aerated compost teas on disease symptoms expression and severity of Lycopersicon esculentum. The experimental layout was a complete randomised block design comprising six treatments, each of which was repeated three times: the negative control plot (Tm-); the positive control or fungicide plot (Tm+); the cow dung compost plot (Cpi); the kitchen manure compost plot (Cpii); the compost tea derived cow dung plot (Tci); and the compost tea derived kitchen manure plot (Tcii). Compost tea derived cow dung was revealed to be richer in elemental nutrients (N, P, K) than compost tea from kitchen manure, and significantly (p < 0.0001) enhanced fruit yield per plant. Similarly, the two composts and their derived compost teas significantly (p < 0.0001) reduced the incidence and severity of disease symptoms compared to the controls, with the highest efficacy accounting for cow dung compost and compost tea. Although the non-aerated compost teas were not amended with micro-organisms, these results suggest that the two compost teas in use were rich enough in microbial pathogen antagonists, and therefore, are perceived as potential alternatives to synthetic chemical fungicides. Future work will attempt to identify these microbial antagonists with highly suppressive activity in the non-aerated compost teas. DOI: http://dx.doi.org/10.3329/ijarit.v4i1.21100 Int. J. Agril. Res. Innov. & Tech. 4 (1): 88-97, June, 201
Numerical analysis of geosynthetics and engineering fill in performance of reconditioned ballasted track
Over the past few decades, geosynthetics have been used extensively during track reconditioning to improve soil stability as they offer many advantages including cost effectiveness, ease of installation and minimal earthworks. Among the wide range of products in the market, geogrid remains the most commonly used geosynthetics for soil reinforcement. The aims of this paper are to investigate the effect of varying subgrade properties on track performance and to examine the effectiveness of geogrids and engineering fill for track reconditioning purposes. In the current study, numerical analyses were conducted using engineering software OptumG2, a finite element program for geotechnical stability and deformation analysis. The results of the parametric study indicated that geogrid inclusion within track substructure has considerable effect on settlement reduction and, in particular, increases the bearing capacity of railway track. The results also suggested that increase in axial stiffness of geogrids has minimal impact on track deformation. The most effective and practical location for geogrid reinforcement was achieved at interface between ballast and capping layers irrespective of the subgrade strength and stiffness. Sensitivity analyses showed that both total settlement and the bearing capacity of the railway track were most affected by the changes in the friction angle of subgrade, compared with cohesion and elastic modulus of subgrade, with or without geogrid reinforcement. The findings concluded that proper design of geogrid reinforcement can eliminate the need for or significantly reduce the thickness of engineering fill for ground improvement purposes
The oncological relevance of fragile sites in cancer
Recent developments in sequencing the cancer genome have provided the first in-depth mapping of structural variants (SV) across 38 tumour types. Sixteen signatures of structural variants have been proposed which broadly characterise the variation seen across cancer types. One signature shows increased duplications and deletions at fragile sites, with little association with the typical DNA repair defects. We discuss how, for many of these fragile sites, the clinical impacts are yet to be explored. One example is NAALADL2, one of the most frequently altered fragile sites in the cancer genome. The copy-number variations (CNVs) which occur at fragile sites, such as NAALADL2, may span many genes without typical DNA repair defects and could have a large impact on cell signalling
Weighing matrices and spherical codes
Mutually unbiased weighing matrices (MUWM) are closely related to an
antipodal spherical code with 4 angles. In the present paper, we clarify the
relationship between MUWM and the spherical sets, and give the complete
solution about the maximum size of a set of MUWM of weight 4 for any order.
Moreover we describe some natural generalization of a set of MUWM from the
viewpoint of spherical codes, and determine several maximum sizes of the
generalized sets. They include an affirmative answer of the problem of Best,
Kharaghani, and Ramp.Comment: Title is changed from "Association schemes related to weighing
matrices
The pH of the skin surface and its impact on the barrier function
The `acid mantle' of the stratum corneum seems to be important for both permeability barrier formation and cutaneous antimicrobial defense. However, the origin of the acidic pH, measurable on the skin surface, remains conjectural. Passive and active influencing factors have been proposed, e. g. eccrine and sebaceous secretions as well as proton pumps. In recent years, numerous investigations have been published focusing on the changes in the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. The pH of the skin follows a sharp gradient across the stratum corneum, which is suspected to be important in controlling enzymatic activities and skin renewal. The skin pH is affected by a great number of endogenous factors, e. g. skin moisture, sweat, sebum, anatomic site, genetic predisposition and age. In addition, exogenous factors like detergents, application of cosmetic products, occlusive dressings as well as topical antibiotics may influence the skin pH. Changes in the pH are reported to play a role in the pathogenesis of skin diseases like irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. Therefore, the use of skin cleansing agents, especially synthetic detergents with a pH of about 5.5, may be of relevance in the prevention and treatment of those skin diseases. Copyright (c) 2006 S. Karger AG, Base
Antinuclear antibodies (ANA) in chronic hepatitis C virus infection: correlates of positivity and clinical relevance.
We examined correlates of antinuclear antibody (ANA) positivity (ANA+) in individuals with chronic hepatitis C virus (HCV) infection and the effect of positivity on clinical outcome of HCV. Pretreatment sera from 645 patients from three centres in Sweden (n = 225), the UK (n = 207) and Italy (n = 213) were evaluated by indirect immunofluorescence on Hep-2 cells for ANA pattern and titre by a single laboratory. Liver biopsies were all scored by one pathologist. A total of 258 patients were subsequently treated with interferon monotherapy. There was a significant difference in the prevalence of ANA (1:40) by geographic location: Lund 4.4%, London 8.7%, Padova 10.3% [odds ratio (OR) = 0.66; 95% CI: 0.46-0.94; P = 0.023]. Duration of HCV infection, age at infection, current age, route of infection, viral genotype, alcohol consumption, fibrosis stage and inflammatory score were not correlated with ANA+ or ANA pattern. Female gender was correlated with ANA+ and this association persisted in multivariable analyses (OR = 3.0; P = 0.002). Increased plasma cells were observed in the liver biopsies of ANA-positive individuals compared with ANA-negative individuals, while a trend towards decreased lymphoid aggregates was observed [hazard ratio (HR) = 9.0, P = 0.037; HR = 0.291, P = 0.118, respectively]. No correlations were observed between ANA positivity and nonresponse to therapy (OR = 1.4; P = 0.513), although ANA+ was correlated with faster rates of liver fibrosis, this was not statistically significant (OR = 1.8; P = 0.1452). Low titre ANA+ should not be a contraindication for interferon treatment. Our observation of increased plasma cells in ANA+ biopsies might suggest B-cell polyclonal activity with a secondary clinical manifestation of increased serum immunoglobulins
Optical Absorption Characteristics of Silicon Nanowires for Photovoltaic Applications
Solar cells have generated a lot of interest as a potential source of clean
renewable energy for the future. However a big bottleneck in wide scale
deployment of these energy sources remain the low efficiency of these
conversion devices. Recently the use of nanostructures and the strategy of
quantum confinement have been as a general approach towards better charge
carrier generation and capture. In this article we have presented calculations
on the optical characteristics of nanowires made out of Silicon. Our
calculations show these nanowires form excellent optoelectronic materials and
may yield efficient photovoltaic devices
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