917 resultados para Frictional Coefficient Ratio


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Antitumor immunity is strongly influenced by the balance of tumor antigen-specific effector and regulatory T cells. However, the impact that vaccine adjuvants have in regulating the balance of antigen-specific T cell populations is not well understood. We found that antigen-specific T regulatory cells (Treg) were induced following subcutaneous vaccination with either OVA or melanoma-derived peptides, with a restricted expansion of effector T cells. Addition of the adjuvants CpG-ODN or Poly(I:C) preferentially amplified effector T cells over Tregs, dramatically increasing the antigen-specific T effector:Treg ratios and inducing polyfunctional effector cells. In contrast, two other adjuvants, imiquimod and Quil A saponin, favored an expansion of antigen-specific Tregs and failed to increase effector T cell:Treg ratios. Following therapeutic vaccination of tumor-bearing mice, high ratios of tumor-specific effector T cells:Tregs in draining lymph nodes were associated with enhanced CD8+ T cell infiltration at the tumor site and a durable rejection of tumors. Vaccine formulations of peptide+CpG-ODN or Poly(I:C) induced selective production of pro-inflammatory Type I cytokines early after vaccination. This environment promoted CD8+ and CD4+ effector T cell expansion over that of antigen-specific Tregs, tipping the effector T cell to Treg balance to favor effector cells. Our findings advance understanding of the influence of different adjuvants on T cell populations, facilitating the rational design of more effective cancer vaccines.

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There are many miles of portland cement concrete pavement in Iowa that due to normal wear, and in some cases accelerated wear from studded tires, the surface has become polished resulting in less than desirable friction values. Retexturing the surface may be an economical way to re-establish desirable friction values. Retexturing by grinding with diamond blades and transverse grooving with diamond blades are two methods of rehabilitating p.c.c. surfaces. MU Inc. of Lebanan, Tennessee proposed to provide without charge to the Iowa Department of Transportation, one 1500 ft x 12 ft section each of three methods of texturing. They are longitudinal grinding, transverse grooving and longitudinal grinding followed by transverse grooving. A section of 1500 feet is needed to properly evaluate a texturing method. It was decided by Iowa DOT personnel that due to possible differential friction it would be undesirable to texture only one lane. The decision was made to do test sections of 1500 ft x 24 ft with the cost of the additional texturing paid by the Iowa DOT. Iowa also has areas where the p.c.c. pavement has faulted at the joints and cracks which results in poor riding quality. Methods of correcting the faulting are to underseal the pavement where needed and/or grinding the surface to eliminate the faulted areas. It was decided to include in this research project a section for profiling by grinding.

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Thin overlays, diamond grinding, longitudinal grooving, transverse grooving, and milling have been successful techniques for restoring frictional properties on portland cement concrete (PCC) pavements. Shotblasting offers a lower cost alternative if successful. Five test sections of shotblasting were placed on IA 9 from Decorah east to the Winneshiek County line (milepost 260.0 to 270.0). Both smooth tire and ribbed tire friction testing (ASTM E274) was performed. The conclusions and recommendations are: Based on the study, friction enhancement by shotblasting has a relatively short service life when measured by the ribbed tire test. However, when measured by the smooth tire test, the friction enhancement is longer lasting. Consideration of shotblasting for friction enhancement may be warranted to gain additional information, particularly when smooth tire friction properties are at issue.

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Triaxial compression tests of two crushed limestones of differing highway service records indicate a fundamental difference in their shear strength -- void ratio relationship. Analyses were based on stress parameters at minimum sample volume, i.e., before there was significant sample dilation due to shear. The better service record sample compacted to higher density, and had a high effective angle of internal friction and zero effective cohesion. The other sample compacted to lower density and had a lower friction angle, but gained significant stability from effective cohesion. Repeated loading-unloading cycles reduced the cohesion, apparently due to modification of the sample structure. Extrapolations of the results to zero void ratio agree with sliding friction data reported on calcite, or with triaxial parameters reported on carbonate rocks.

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Many times during the past four years we have seen ranges in the durability factor for a single coarse aggregate source that were too great to be explained by variations in the coarse aggregate alone. The durability test (ASTM C 666 Method B) as presently used is a test of the concrete system rather than that of a particular coarse aggregate. An informal study of current durability factor data indicates that w/c ratio and/or percentage of air may be critical to beam growth and durability factor. The purpose of this project, R-258, is to determine the extent w/c ratio and air content variations have on beam growth and durability factor when other factors including coarse aggregate gradation are held constant.

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Two goals were pursued in this research: first, to evaluate statistically some effects of sample preparation and instrument geometry on reproducibility of X-ray diffraction intensity data; and second, to develop a procedure for finding minimum peak and background counting times for a desired level of accuracy. The ratio of calcite to dolomite in limestones was determined in trials. Ultra-fine wet grinding of the limestone in porcelain impact type ball mill gave most consistent X-ray results, but caused considerable line broadening, and peaks were best measured on an area count basis. Sample spinning reduced variance about one third, and a coarse beam-medium detector slit arrangement was found to be best. An equation is developed relating coefficient of variation of a count ratio to peak and background counts. By use of the equation or graphs the minimum coefficient of variation is predicted from one fast scan, and the number and optimum arrangement of additional counting periods to reduce variation to a desired limit may be obtained. The calculated coefficient is the maximum which may be attributed to the counting statistic but does not include experimental deviations.

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Friction testing of pavements has been a continuing effort by the Iowa Department of Transportation since 1969. This report details results of tests of asphaltic concrete pavements on the primary and interstate road systems. Both sprinkle treated and non-sprinkle treated pavements placed between 1975 - 1985 are included. A total of 1785 miles representing 216 separate paving projects were examined. The effect of fog sealing sprinkle treated pavements was studied by testing friction levels before and after the application of the fog seals. Conclusions of the report are: 1. Current aggregate selection criteria for a.c. pavement surface courses provides adequate friction levels through 10 years and should remain effective through a 15 year design life. 2. Sprinkle treatment of pavements has, for the most part, provided macrotexture in the pavement surface as evidenced by smooth tire testing. 3. Fog sealing sprinkle treated pavements does not significantly alter the friction properties.

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This article summarizes the configurations involving isotope ratio mass spectrometry (IRMS) technology available at the CCiTUB and the wide range of possible applications. Some examples of these applications are shown.

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This work was conducted to study alternatives for reduction of the bull:cow ratio in the Brazilian lowland and, therefore, lower the production costs for the local beef cattle industry. The ratios 1:10, 1:25, and 1:40 were used in native pastures with a mean stocking rate of 0.27 mature animal unit per hectare over two consecutive breeding seasons. Statistical analysis did not show any effect (P>0.05) of year (P = 0.2097), animal category (P = 0.0773), bull:cow ratio (0.8134) on reproductive performance. However, the pregnancy rate in a multiple bull system was higher (P = 0.0228) than in the individual bull system. An evaluation of the economic impact of this management system in the extensive Lowland herds showed that at the ratio of 1:10 the bulls were sub utilized.

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The objectives of this study were to establish DRIS norms for sugarcane crop, to compare mean yield, foliar nutrient contents and variance of nutrient ratios of low- and high-yielding groups and to compare mean values of nutrient ratios selected as the DRIS norms of low- and high-yielding groups. Leaf samples (analyzed for N, P, K, Ca, Mg, S, Cu, Mn and Zn contents) and respective yields were collected in 126 commercial sugarcane fields in Rio de Janeiro State, Brazil and used to establish DRIS norms for sugarcane. Nearly all nutrient ratios selected as DRIS norms (77.8%) showed statistical differences between mean values of the low- and high-yielding groups. These different nutritional balances between the low- and high-yielding groups indicate that the DRIS norms developed in this paper are reliable. The DRIS norms for micronutrients with high S²l /S²h ratio and low coefficient of variation found can provide more security to evaluate the micronutrient status of sugarcane.

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This study aimed to use the plantar pressure insole for estimating the three-dimensional ground reaction force (GRF) as well as the frictional torque (T(F)) during walking. Eleven subjects, six healthy and five patients with ankle disease participated in the study while wearing pressure insoles during several walking trials on a force-plate. The plantar pressure distribution was analyzed and 10 principal components of 24 regional pressure values with the stance time percentage (STP) were considered for GRF and T(F) estimation. Both linear and non-linear approximators were used for estimating the GRF and T(F) based on two learning strategies using intra-subject and inter-subjects data. The RMS error and the correlation coefficient between the approximators and the actual patterns obtained from force-plate were calculated. Our results showed better performance for non-linear approximation especially when the STP was considered as input. The least errors were observed for vertical force (4%) and anterior-posterior force (7.3%), while the medial-lateral force (11.3%) and frictional torque (14.7%) had higher errors. The result obtained for the patients showed higher error; nevertheless, when the data of the same patient were used for learning, the results were improved and in general slight differences with healthy subjects were observed. In conclusion, this study showed that ambulatory pressure insole with data normalization, an optimal choice of inputs and a well-trained nonlinear mapping function can estimate efficiently the three-dimensional ground reaction force and frictional torque in consecutive gait cycle without requiring a force-plate.

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Two likelihood ratio (LR) approaches are presented to evaluate the strength of evidence of MDMA tablet comparisons. The first one is based on a more 'traditional' comparison of MDMA tablets by using distance measures (e.g., Pearson correlation distance or a Euclidean distance). In this approach, LRs are calculated using the distribution of distances between tablets of the same-batch and that of different-batches. The second approach is based on methods used in some other fields of forensic comparison. Here LRs are calculated based on the distribution of values of MDMA tablet characteristics within a specific batch and from all batches. The data used in this paper must be seen as examples to illustrate both methods. In future research the methods can be applied to other and more complex data. In this paper, the methods and their results are discussed, considering their performance in evidence evaluation and several practical aspects. With respect to evidence in favor of the correct hypothesis, the second method proved to be better than the first one. It is shown that the LRs in same-batch comparisons are generally higher compared to the first method and the LRs in different-batch comparisons are generally lower. On the other hand, for operational purposes (where quick information is needed), the first method may be preferred, because it is less time consuming. With this method a model has to be estimated only once in a while, which means that only a few measurements have to be done, while with the second method more measurements are needed because each time a new model has to be estimated.

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Purpose: The increase of apparent diffusion coefficient (ADC) in treated hepatic malignancies compared to pre-therapeutic values has been interpreted as treatment success; however, the variability of ADC measurements remains unknown. Furthermore, ADC has been usually measured in the whole lesion, while measurements should be probably centered on the area with the most restricted diffusion (MRDA) as it represents potential tumoral residue. Our objective was to compare the inter/intraobserver variability of ADC measurements in the whole lesion and in MRDA. Material and methods: Forty patients previously treated with chemoembolization or radiofrequency were evaluated (20 on 1.5T and 20 on 3.0T). After consensual agreement on the best ADC image, two readers measured the ADC values using separate regions of interest that included the whole lesion and the whole MRDA without exceeding their borders. The same measurements were repeated two weeks later. Spearman test and the Bland-Altman method were used. Results: Interobserver correlation in ADC measurements in the whole lesion and MRDA was as follows: 0.962 and 0.884. Intraobserver correlation was, respectively, 0.992 and 0.979. Interobserver limits of variability (mm2/sec*10-3) were between -0.25/+0.28 in the whole lesion and between -0.51/+0.46 in MRDA. Intraobserver limits of variability were, respectively: -0.25/+0.24 and -0.43/+0.47. Conclusion: We observed a good inter/intraobserver correlation in ADC measurements. Nevertheless, a limited variability does exist, and it should be considered when interpreting ADC values of hepatic malignancies.