808 resultados para 862


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BACKGROUND: BRAF mutations are frequent in melanoma but their prognostic significance remains unclear. OBJECTIVE: We sought to further evaluate the prognostic value of BRAF mutations in localized cutaneous melanoma. METHODS: We undertook an observational retrospective study of 147 patients with localized invasive (stages I and II) cutaneous melanomas to determine the prognostic value of BRAF mutation status. RESULTS: After a median follow-up of 48 months, patients with localized melanomas with BRAF-mutant melanomas exhibited poorer disease-free survival than those with BRAF-wt genotype (hazard ratio 2.2, 95% confidence interval 1.1-4.3) even after adjustment for Breslow thickness, tumor ulceration, location, age, sex, and tumor mitotic rate. LIMITATIONS: The retrospective design and the small number of events are limitations. CONCLUSIONS: Our findings suggest that reappraisal of clinical treatment approaches for patients with localized melanoma harboring tumors with BRAF mutation might be warranted

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Background Because many acute cerebral ischemic events are caused by rupture of vulnerable carotid atheroma and subsequent thrombosis, the present study used both idealized and patient-specific carotid atheromatous plaque models to evaluate the effect of structural determinants on stress distributions within plaque. Methods and Results Using a finite element method, structural analysis was performed using models derived from in vivo high-resolution magnetic resonance imaging (MRI) of carotid atheroma in 40 non-consecutive patients (20 symptomatic, 20 asymptomatic). Plaque components were modeled as hyper-elastic materials. The effects of varying fibrous cap thickness, lipid core size and lumen curvature on plaque stress distributions were examined. Lumen curvature and fibrous cap thickness were found to be major determinants of plaque stress. The size of the lipid core did not alter plaque stress significantly when the fibrous cap was relatively thick. The correlation between plaque stress and lumen curvature was significant for both symptomatic (p = 0.01; correlation coefficient: 0.689) and asymptomatic patients (p = 0.01; correlation coefficient: 0.862). Lumen curvature in plaques of symptomatic patients was significantly larger than those of asymptomatic patients (1.50±1.0mm-1 vs 1.25±0.75 mm-1; p = 0.01). Conclusion Specific plaque morphology (large lumen curvature and thin fibrous cap) is closely related to plaque vulnerability. Structural analysis using high-resolution MRI of carotid atheroma may help in detecting vulnerable atheromatous plaque and aid the risk stratification of patients with carotid disease.

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Knowledge of the temporal and spatial characteristics of chokka squid (Loligo vulgaris reynaudii) biology in South African waters is limited, so the possibility of there being a geographically fragmented stock was examined by investigating the distribution of maturity patterns for the species, covering all known spawning areas and using both historical and recent data. Gonadosomatic indices (GSI) varied between year-round consistency and apparent seasonal peaks in both summer and winter; there was no clear spatial pattern. Monthly percentage maturity provided further evidence for two peak reproductive periods each year, although mature squid were present throughout. Sex ratios demonstrated great variability between different areas and life history stages. Male-biased sex ratios were only apparent on the inshore spawning grounds and ranged between 1.118:1 and 4.267:1. Size at sexual maturity was also seasonal, squid maturing smaller in winter/spring than in summer/autumn. Also, squid in the east matured smaller than squid in the west. Although the results from the present study do not provide conclusive evidence of distinct geographic populations, squid likely spawn over a significantly larger area of the Agulhas Bank than previously estimated, and squid on the west coast of South Africa may return to spawn on the western portion of the Agulhas Bank. It remains likely, however, that the east and west coast populations are a single stock and that migration of juveniles to the west coast and their subsequent return as sub-adults is an integral but non-essential and variable part of the life history.

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Knowledge of drag force is an important design parameter in aerodynamics. Measurement of aerodynamic forces at hypersonic speed is a challenge and usually ground test facilities like shock tunnels are used to carry out such tests. Accelerometer based force balances are commonly employed for measuring aerodynamic drag around bodies in hypersonic shock tunnels. In this study, we present an analysis of the effect of model material on the performance of an accelerometer balance used for measurement of drag in impulse facilities. From the experimental studies performed on models constructed out of Bakelite HYLEM and Aluminum, it is clear that the rigid body assumption does not hold good during the short testing duration available in shock tunnels. This is notwithstanding the fact that the rubber bush used for supporting the model allows unconstrained motion of the model during the short testing time available in the shock tunnel. The vibrations induced in the model on impact loading in the shock tunnel are damped out in metallic model, resulting in a smooth acceleration signal, while the signal become noisy and non-linear when we use non-isotropic materials like Bakelite HYLEM. This also implies that careful analysis and proper data reduction methodologies are necessary for measuring aerodynamic drag for non-metallic models in shock tunnels. The results from the drag measurements carried out using a 60 degrees half angle blunt cone is given in the present analysis.

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The use of the multiple Fourier method to analyses the stress distribution in the and regions of as a post-tensioned prestressed concrete beam had shown. The multiple Fourier method demonstrated have is a relatively new method for solving those problems for which the “Saint Vansant principle” is not applicable, The actual three-dimensional problem and a two-dimensional simplified representation of it are treated. The two-dimensional case is treated first and rather completely to gain further experience with multiple Fourier procedure, the appropriate Galerkin Vector for the three-dimensional case is found and the required relations between the arbitrary functions are stated.

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No-tillage (NT) practice, where straw is retained on the soil surface, is increasingly being used in cereal cropping systems in Australia and elsewhere. Compared to conventional tillage (CT), where straw is mixed with the ploughed soil, NT practice may reduce straw decomposition, increase nitrogen immobilisation and increase organic carbon in the soil. This study examined 15N-labelled wheat straw (stubble) decomposition in four treatments (NT v. CT, with N rates of 0 and 75 kg/ha.year) and assessed the tillage and fertiliser N effects on mineral N and organic C and N levels over a 10-year period in a field experiment. NT practice decreased the rate of straw decomposition while fertiliser N application increased it. However, there was no tillage practice x N interaction. The mean residence time of the straw N in soil was more than twice as long under the NT (1.2 years) as compared to the CT practice (0.5 years). In comparison, differences in mean residence time due to N fertiliser treatment were small. However, tillage had generally very little effect on either the amounts of mineral N at sowing or soil organic C (and N) over the study period. While application of N fertiliser increased mineral N, it had very little effect on organic C over a 10-year period. Relatively rapid decomposition of straw and short mean residence time of straw N in a Vertisol is likely to have very little long-term effect on N immobilisation and organic C level in an annual cereal cropping system in a subtropical, semiarid environment. Thus, changing the tillage practice from CT to NT may not necessitate additional N requirement unless use is made of additional stored water in the soil or mineral N loss due to increased leaching is compensated for in N supply to crops.

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The impact of erroneous genotypes having passed standard quality control (QC) can be severe in genome-wide association studies, genotype imputation, and estimation of heritability and prediction of genetic risk based on single nucleotide polymorphisms (SNP). To detect such genotyping errors, a simple two-locus QC method, based on the difference in test statistic of association between single SNPs and pairs of SNPs, was developed and applied. The proposed approach could detect many problematic SNPs with statistical significance even when standard single SNP QC analyses fail to detect them in real data. Depending on the data set used, the number of erroneous SNPs that were not filtered out by standard single SNP QC but detected by the proposed approach varied from a few hundred to thousands. Using simulated data, it was shown that the proposed method was powerful and performed better than other tested existing methods. The power of the proposed approach to detect erroneous genotypes was approximately 80% for a 3% error rate per SNP. This novel QC approach is easy to implement and computationally efficient, and can lead to a better quality of genotypes for subsequent genotype-phenotype investigations.

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Diluents (either low molecular weight compounds orother polymers) are known to modify the morphology, the rates of nucleation and growth of polymers 1- 4. Recentlybinary systems in which both the components crystallize simultaneously to give a eutectic solid have been studied with great interest. Carbonnei et al.

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The accretion disk around a compact object is a nonlinear general relativistic system involving magnetohydrodynamics. Naturally, the question arises whether such a system is chaotic (deterministic) or stochastic (random) which might be related to the associated transport properties whose origin is still not confirmed. Earlier, the black hole system GRS 1915+105 was shown to be low-dimensional chaos in certain temporal classes. However, so far such nonlinear phenomena have not been studied fairly well for neutron stars which are unique for their magnetosphere and kHz quasi-periodic oscillation (QPO). On the other hand, it was argued that the QPO is a result of nonlinear magnetohydrodynamic effects in accretion disks. If a neutron star exhibits chaotic signature, then what is the chaotic/correlation dimension? We analyze RXTE/PCA data of neutron stars Sco X-1 and Cyg X-2, along with the black hole Cyg X-1 and the unknown source Cyg X-3, and show that while Sco X-1 and Cyg X-2 are low dimensional chaotic systems, Cyg X-1 and Cyg X-3 are stochastic sources. Based on our analysis, we argue that Cyg X-3 may be a black hole.

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Colour is an essential aspect of our daily life, and still, it is a neglected issue within marketing research. The main reason for studying colours is to understand the impact of colours on consumer behaviour, and thus, colours should be studied when it comes to branding, advertising, packages, interiors, and the clothes of the employees, for example. This was an exploratory study about the impact of colours on packages. The focus was on low-involvement purchasing, where the consumer puts limited effort into the decision-making. The basis was a scenario in which the consumer faces an unpredictable problem needing immediate action. The consumer may be in hurry, which indicate time pressure. The consumer may lack brand preferences, or the preferred brand may be out of stock. The issue is that the choice is to be made at the point of purchase. Further, the purchasing involves product classes where the core products behind the brands are indistinguishable from each other. Three research questions were posed. Two questions were answered by conjoint analysis, i.e. if colours have an impact on decision-making and if a possible impact is related to the product class. 16 hypothetical packages were designed in two product classes within the healthcare, i.e. painkillers and medicine against sore throats. The last research question aimed at detecting how an analysis could be carried out in order to understand the impact of colours. This question was answered by conducting interviews that were analysed by applying laddering method and a semiotics approach. The study found that colours do indeed have an impact on consumer behaviour, this being related to the context, such as product class. The role of colours on packages was found to be threefold: attention, aesthetics, and communication. The study focused on colours as a means of communication, and it proposes that colours convey product, brand, and product class meanings, these meanings having an impact on consumers’ decision-making at the point of purchase. In addition, the study demonstrates how design elements such as colours can be understood by regarding them as non-verbal signs. The study also presents an empirical design, involving quantitative and qualitative techniques that can be used to gain in depth understanding of the impact of design elements on consumer behaviour. Hannele Kauppinen is associated with CERS, the Centre for Relationship Marketing and Service Management of the Swedish School of Economics and Business Administration

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Linear optimization model was used to calculate seven wood procurement scenarios for years 1990, 2000 and 2010. Productivity and cost functions for seven cutting, five terrain transport, three long distance transport and various work supervision and scaling methods were calculated from available work study reports. All method's base on Nordic cut to length system. Finland was divided in three parts for description of harvesting conditions. Twenty imaginary wood processing points and their wood procurement areas were created for these areas. The procurement systems, which consist of the harvesting conditions and work productivity functions, were described as a simulation model. In the LP-model the wood procurement system has to fulfil the volume and wood assortment requirements of processing points by minimizing the procurement cost. The model consists of 862 variables and 560 restrictions. Results show that it is economical to increase the mechanical work in harvesting. Cost increment alternatives effect only little on profitability of manual work. The areas of later thinnings and seed tree- and shelter wood cuttings increase on cost of first thinnings. In mechanized work one method, 10-tonne one grip harvester and forwarder, is gaining advantage among other methods. Working hours of forwarder are decreasing opposite to the harvester. There is only little need to increase the number of harvesters and trucks or their drivers from today's level. Quite large fluctuations in level of procurement and cost can be handled by constant number of machines, by alternating the number of season workers and by driving machines in two shifts. It is possible, if some environmental problems of large scale summer time harvesting can be solved.

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Thin films of zirconia have been synthesized using reactive DC magnetron sputtering. It has been found that films with good optical constants, high refractive index (1.9 at 600 nm) and low extinction coefficient can be prepared al ambient temperatures. The optical constants and band gnp and hence the composition nle dependent on the deposition parameters such as target power, rate of deposition and oxygen background pressure. Thermal annealing of the films revealed that tile films showed optical and crystalline inhomogeneity and also large variations in optical constants.

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Azidothymidine (AZT), which has been extensively used as an antiviral agent in the treatment of AIDS, showed strong inhibition of growth of Sp2/0 cells in vitro. AZT-treated cells showed a decrease in viability in a dose-dependent manner. AZT specifically induced typical apoptotic cell death with DNA double-strand cleavage and subsequent formation of apoptotic bodies. The induction of DNA double-strand cleavage into the oligonucleosomal ladder by AZT was protected in the presence of thymidine or uridine. An increase in endonuclease activity from nuclear extract of AZT-treated cells was observed. The enzyme activity was found to be Ca2+- and Mg2+-dependent and was inhibited by zinc acetate. A marked enhancement of PARP activity was observed in AZT-treated cells. These observations show that AZT can trigger both morphological and biochemical changes typical of apoptosis in the mouse myeloma cell line Sp2/0.

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In data mining, an important goal is to generate an abstraction of the data. Such an abstraction helps in reducing the space and search time requirements of the overall decision making process. Further, it is important that the abstraction is generated from the data with a small number of disk scans. We propose a novel data structure, pattern count tree (PC-tree), that can be built by scanning the database only once. PC-tree is a minimal size complete representation of the data and it can be used to represent dynamic databases with the help of knowledge that is either static or changing. We show that further compactness can be achieved by constructing the PC-tree on segmented patterns. We exploit the flexibility offered by rough sets to realize a rough PC-tree and use it for efficient and effective rough classification. To be consistent with the sizes of the branches of the PC-tree, we use upper and lower approximations of feature sets in a manner different from the conventional rough set theory. We conducted experiments using the proposed classification scheme on a large-scale hand-written digit data set. We use the experimental results to establish the efficacy of the proposed approach. (C) 2002 Elsevier Science B.V. All rights reserved.