889 resultados para 010203 Calculus of Variations, Systems Theory and Control Theory
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A variant 35 kb upstream of the HLA-C gene (-35C/T) was previously shown to associate with HLA-C mRNA expression level and steady-state plasma HIV RNA levels. We genotyped this variant in 1,698 patients of European ancestry with HIV. Individuals with known seroconversion dates were used for disease progression analysis and those with longitudinal viral load data were used for viral load analysis. We further tested cell surface expression of HLA-C in normal donors using an HLA-C-specific antibody. We show that the -35C allele is a proxy for high HLA-C cell surface expression, and that individuals with high-expressing HLA-C alleles progress more slowly to AIDS and control viremia significantly better than individuals with low HLA-C expressing alleles. These data strongly implicate high HLA-C expression levels in more effective control of HIV-1, potentially through better antigen presentation to cytotoxic T lymphocytes or recognition and killing of infected cells by natural killer cells.
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This work is focused on the study of the fine speckle contrast present in planar view observations of matched and mismatched InGaAs layers grown by molecular beam epitaxy on InP substrates. Our results provide experimental evidence of the evolution of this fine structure with the mismatch, layer thickness, and growth temperature. The correlation of the influence of all these parameters on the appearance of the contrast modulation points to the development of the fine structure during the growth. Moreover, as growth proceeds, this structure shows a dynamic behavior which depends on the intrinsic layer substrate stress.
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This article analyses the varying influence across time of the "epistemic community" of free-market economists on immigration policy making in Switzerland. To this end, a framework for the analysis of the impact of economic expertise is provided, and then used in an historical analysis comparing the 1960s with the 1990s. Whereas this influence can be considered to have been weak in the 1960s, it gained significantly in importance in the 1990s, when a period of economic unrest seriously challenged previous immigration policies. It is argued that economic experts played an important role in framing the reforms undertaken during this latter period, notably by providing a "credible causal story" about the links between the existing immigration policy and the social problems which arose in the country in the 1990s. As compared to the 1960s, economic expertise in the 1990s enjoyed more credibility, more political support and took full advantage of a more uncertain social and economic context
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In agricultural systems the N-NH4+ and N-NO3- contents is significantly affected by soil management. This study investigated the dynamics of inorganic nitrogen (N; NH4+ and NO3-) in an experimental evaluation of soil management systems (SMSs) adopted in 1988 at the experimental station of the ABC Foundation in Ponta Grossa, in the Central South region of the State of Paraná. The objective of this study was to evaluate the changes in N-NH4+ and N-NO3- flux in the surface layer of a Red Latosol arising from SMSs over a 12-month period. The experiment was arranged in a completely randomized block design in split plots, in three replications. The plots consisted of the following SMSs: 1) conventional tillage (CT); 2) minimum tillage (MT); 3) no-tillage with chisel plow every three years (NT CH); and 4) continuous no-tillage (CNT). To evaluate the dynamics of inorganic N, the subplots represented samplings (11 sampling times, T1 - T11). The ammonium N (N-NH4+) and nitric N (N-NO3-) contents were higher in systems with reduced tillage (MT and NT CH) and without tillage (CNT) than in the CT system. In the period from October 2003 to February 2004, the N-NH4+ was higher than the N-NO3- soil content. Conversely, in the period from May 2004 to July 2004, the N-NO3- was higher than the N-NH4+ content. The greatest fluctuation in the N-NH4+ and N-NO3- contents occurred in the 0-2.5 cm layer, and the highest peak in the N-NH4+ and N-NO3- concentrations occurred after the surface application of N. Both N-NH4+ and N-NO3- were strongly correlated with the soil organic C content, which indicated that these properties vary together in the system.
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Brown adipocytes oxidize fatty acids to produce heat in response to cold or to excessive energy intake; stimulation of brown fat development and function may thus counteract obesity. Brown adipogenesis requires activation of the transcription factor C/EBPβ and recruitment of the zinc finger protein Prdm16, but upstream inducers of these proteins are incompletely defined. Here, we show that genetic inactivation of Plac8, a gene encoding an evolutionarily conserved protein, induces cold intolerance, and late-onset obesity, as well as abnormal morphology and impaired function of brown adipocytes. Using brown preadipocyte lines we show that Plac8 is required for brown fat differentiation, that its overexpression induces C/EBPβ and Prdm16, and that upon induction of differentiation Plac8 associates with C/EBPβ and binds to the C/EBPβ promoter to induce its transcription. Thus, Plac8 is a critical upstream regulator of brown fat differentiation and function that acts, at least in part, by inducing C/EBPβ expression.
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Only limited data is available on the relationship between family history of laryngeal and other neoplasms and laryngeal cancer risk. We investigated the issue using data from a multicentre case-control study conducted in Italy and Switzerland between 1992 and 2009 including 852 cases with histologically confirmed laryngeal cancer and 1970 controls admitted to hospital for acute, non neoplastic conditions. Unconditional logistic regression models adjusted for age, sex, study center, education, tobacco smoking, alcohol drinking and number of siblings were used to estimate the odds ratios (ORs) of laryngeal cancer. The multivariate OR was 2.8 (95% confidence interval [CI], 1.5-5.3) in subjects reporting a first-degree relative with laryngeal cancer, as compared to subjects with no family history. The OR was higher when the relative was diagnosed before 60 years of age (OR = 3.5, 95% CI 1.4-8.8). As compared to subjects without family history, non-smokers, and moderate drinkers, the OR was 37.1 (95% CI 9.9-139.4) for current smokers, heavy drinkers, with family history of laryngeal cancer. Family history of colorectal (OR = 1.5, 95% CI 1.0-2.3) and kidney (OR = 3.8, 95% CI 1.2-12.1) cancer were also associated to an increased risk of laryngeal cancer, while no significant increase in risk was found for family history of cancer at all sites, excluding the larynx (OR = 1.1).
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Management systems may lead to a loss of soil physical quality as a result of removal of the plant cover and excessive agricultural mechanization. The hypothesis of this study was that the soil aggregate stability, bulk density, macro- and microporosity, and the S index and saturated hydraulic conductivity may be used as indicators of the soil physical quality. The aim was to study the effects of different periods and managements on the physical attributes of a medium-textured Red Oxisol under soybean and corn for two growing seasons, and determine which layers are most susceptible to variations. A completely randomized experimental design was used with split plots (five treatments and four layers), with four replications. The treatments in 2008/09 consisted of: five years of no-tillage (NTS5), seven years of no-tillage (NTS7), nine years of no-tillage (NTS9), conventional tillage (CTS) and an adjacent area of native forest (NF). The treatments were extended for another year, identified in 2009/10 as: NTS6, NTS8, NTS10, CTS and NF. The soil layers 0-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.30 m were sampled. The highest S index values were observed in the treatment CTS in the 0-0.05 m layer (0.106) and the 0.05-0.10 m layer (0.099) in 2008/09, and in the 0-0.05 m layer (0.066) in 2009/10. This fact may be associated with soil turnover, resulting in high macroporosity in this treatment. In contrast, in the NTS, limiting macroporosity values were observed in some layers (below 0.10 m³ m-3). Highest aggregate stability as well as the highest saturated hydraulic conductivity (Kθ) values were observed in NF in relation to the other treatments. In 2009/10, the Kθ in NF differed only from NTS10. This study showed that the use of the S index alone cannot be recommended as an absolute indicator of the soil physical quality, even at values greater than 0.035.
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A practical activity designed to introduce wavefront coding techniques as a method to extend the depth of field in optical systems is presented. The activity is suitable for advanced undergraduate students since it combines different topics in optical engineering such as optical system design, aberration theory, Fourier optics, and digital image processing. This paper provides the theoretical background and technical information for performing the experiment. The proposed activity requires students able to develop a wide range of skills since they are expected to deal with optical components, including spatial light modulators, and develop scripts to perform some calculations.
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Thirty monoclonal antibodies from eight laboratories exchanged after the First Workshop on Monoclonal Antibodies to Human Melanoma held in March 1981 at NIH were tested in an antibody-binding radioimmunoassay using a panel of 28 different cell lines. This panel included 12 melanomas, three neuroblastomas, four gliomas, one retinoblastoma, four colon carcinomas, one lung carcinoma, one cervical carcinoma, one endometrial carcinoma, and one breast carcinoma. The reactivity pattern of the 30 monoclonal antibodies tested showed that none of them were directed against antigens strictly restricted to melanoma, but that several of them recognize antigenic structures preferentially expressed on melanoma cells. A large number of antibodies were found to crossreact with gliomas and neuroblastomas. Thus, they seem to recognize neuroectoderm associated differentiation antigens. Four monoclonal antibodies produced in our laboratory were further studied for the immunohistological localization of melanoma associated antigens on fresh tumor material. In a three-layer biotin-avidin-peroxidase system each antibody showed a different staining pattern with the tumor cells, suggesting that they were directed against different antigens.
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The multiscale finite-volume (MSFV) method is designed to reduce the computational cost of elliptic and parabolic problems with highly heterogeneous anisotropic coefficients. The reduction is achieved by splitting the original global problem into a set of local problems (with approximate local boundary conditions) coupled by a coarse global problem. It has been shown recently that the numerical errors in MSFV results can be reduced systematically with an iterative procedure that provides a conservative velocity field after any iteration step. The iterative MSFV (i-MSFV) method can be obtained with an improved (smoothed) multiscale solution to enhance the localization conditions, with a Krylov subspace method [e.g., the generalized-minimal-residual (GMRES) algorithm] preconditioned by the MSFV system, or with a combination of both. In a multiphase-flow system, a balance between accuracy and computational efficiency should be achieved by finding a minimum number of i-MSFV iterations (on pressure), which is necessary to achieve the desired accuracy in the saturation solution. In this work, we extend the i-MSFV method to sequential implicit simulation of time-dependent problems. To control the error of the coupled saturation/pressure system, we analyze the transport error caused by an approximate velocity field. We then propose an error-control strategy on the basis of the residual of the pressure equation. At the beginning of simulation, the pressure solution is iterated until a specified accuracy is achieved. To minimize the number of iterations in a multiphase-flow problem, the solution at the previous timestep is used to improve the localization assumption at the current timestep. Additional iterations are used only when the residual becomes larger than a specified threshold value. Numerical results show that only a few iterations on average are necessary to improve the MSFV results significantly, even for very challenging problems. Therefore, the proposed adaptive strategy yields efficient and accurate simulation of multiphase flow in heterogeneous porous media.
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Selostus: Ilmaston lämpenemisen vaikutus perunaruttoon
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Vegetable production in conservation tillage has increased in Brazil, with positive effects on the soil quality. Since management systems alter the quantity and quality of organic matter, this study evaluated the influence of different management systems and cover crops on the organic matter dynamics of a dystrophic Red Latosol under vegetables. The treatments consisted of the combination of three soil tillage systems: no-tillage (NT), reduced tillage (RT) and conventional tillage (CT) and of two cover crops: maize monoculture and maize-mucuna intercrop. Vegetables were grown in the winter and the cover crops in the summer for straw production. The experiment was arranged in a randomized block design with four replications. Soil samples were collected between the crop rows in three layers (0.0-0.05, 0.05-0.10, and 0.10-0.30 m) twice: in October, before planting cover crops for straw, and in July, during vegetable cultivation. The total organic carbon (TOC), microbial biomass carbon (MBC), oxidizable fractions, and the carbon fractions fulvic acid (C FA), humic acid (C HA) and humin (C HUM) were determined. The main changes in these properties occurred in the upper layers (0.0-0.05 and 0.05-0.10 m) where, in general, TOC levels were highest in NT with maize straw. The MBC levels were lowest in CT systems, indicating sensitivity to soil disturbance. Under mucuna, the levels of C HA were lower in RT than NT systems, while the C FA levels were lower in RT than CT. For vegetable production, the C HUM values were lowest in the 0.05-0.10 m layer under CT. With regard to the oxidizable fractions, the tillage systems differed only in the most labile C fractions, with higher levels in NT than CT in the 0.0-0.05 m layer in both summer and winter, with no differences between these systems in the other layers. The cabbage yield was not influenced by the soil management system, but benefited from the mulch production of the preceding maize-mucuna intercrop as cover plant.
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OBJECTIVE: Evaluation of the quantitative antibiogram as an epidemiological tool for the prospective typing of methicillin-resistant Staphylococcus aureus (MRSA), and comparison with ribotyping. METHODS: The method is based on the multivariate analysis of inhibition zone diameters of antibiotics in disk diffusion tests. Five antibiotics were used (erythromycin, clindamycin, cotrimoxazole, gentamicin, and ciprofloxacin). Ribotyping was performed using seven restriction enzymes (EcoRV, HindIII, KpnI, PstI, EcoRI, SfuI, and BamHI). SETTING: 1,000-bed tertiary university medical center. RESULTS: During a 1-year period, 31 patients were found to be infected or colonized with MRSA. Cluster analysis of antibiogram data showed nine distinct antibiotypes. Four antibiotypes were isolated from multiple patients (2, 4, 7, and 13, respectively). Five additional antibiotypes were isolated from the remaining five patients. When analyzed with respect to the epidemiological data, the method was found to be equivalent to ribotyping. Among 206 staff members who were screened, six were carriers of MRSA. Both typing methods identified concordant of MRSA types in staff members and in the patients under their care. CONCLUSIONS: The quantitative antibiogram was found to be equivalent to ribotyping as an epidemiological tool for typing of MRSA in our setting. Thus, this simple, rapid, and readily available method appears to be suitable for the prospective surveillance and control of MRSA for hospitals that do not have molecular typing facilities and in which MRSA isolates are not uniformly resistant or susceptible to the antibiotics tested.