Computation of 2-groups of positive classes of exceptional number fields

We present an algorithm for computing the 2-group of the positive divisor classes of a number field F in case F has exceptional dyadic places. As an application, we compute the 2-rank of the wild kernel WK2(F) in K2(F) for such number fields

An Optimizing Method for Screening in A Mixture Design Experiment

Mixture experiments, is when the responses are subject to the proportion of the components in the mixture and not on the total amount of the mixture. When we have a lot of component is a little tedious to analyze so we use screening methods in a mixture design using the Cox model. Using this we develop methods a new method for screening in a mixture setting

Phage display selection of HIV specific conserved mimotopes with IgG from long-term non-progressors

Poster presentation Background The aim of this study is to identify conserved epitopes of HIV-1 neutralizing antibodies in polyclonal plasma from LTNP to finally derive vaccine candidates. Materials and methods The presence of neutralizing antibodies in 9 LTNP sera was proved by in vitro neutralization assays. Phage displayed peptide libraries were screened with LTNP IgG. HIV-specific mimotopes were analyzed for homology to the gp120 structure by a software (3DEX) especially developed for this purpose. Mice were immunized with interesting phages and their sera were analyzed for neutralizing activities against HIV-1. Results After biopannings, between 19% and 75% HIV-specific phage clones were identified by ELISA. Mimotope sequences were identified and could be aligned by 3DEX to linear or conformational epitopes on gp120. A peptide specific immune response was detected in sera of immunized mice. The first mice sera analyzed showed neutralizing activities against HIV-1. Conclusion Mimotopes could be selected from LTNP sera that represent conformational epitopes on gp120. Those ones inducing neutralizing antibodies upon immunization potentially are suited to derive vaccine candidates

Microstructural and XRD analysis and study of the properties of the system Ti-TiAl-B4C processed under different operational conditions

High specific modulus materials are considered excellent for the aerospace industry. The system Ti-TiAl-B4C is presented herein as an alternative material. Secondary phases formed in situ during fabrication vary depending on the processing conditions and composition of the starting materials. The final behaviors of these materials are therefore difficult to predict. This research focuses on the study of the system Ti-TiAl-B4C, whereby relations between microstructure and properties can be predicted in terms of the processing parameters of the titanium matrix composites (TMCs). The powder metallurgy technique employed to fabricate the TMCs was that of inductive hot pressing (iHP) since it offers versatility and flexibility. The short processing time employed (5 min) was set in order to test the temperature as a major factor of influence in the secondary reactions. The pressure was also varied. In order to perform this research, not only were X-Ray Diffraction (XRD) analyses performed, but also microstructural characterization through Scanning Electron Microscopy (SEM). Significant results showed that there was an inflection temperature from which the trend to form secondary compounds depended on the starting material used. Hence, the addition of TiAl as an elementary blend or as prealloyed powder played a significant role in the final behavior of the TMCs fabricated, where the prealloyed TiAl provides a better precursor of the formation of the reinforcement phases from 1100 °C regardless of the pressur

Computation of 2-groups of narrow logarithmic divisor classes of number fields

We present an algorithm for computing the 2-group of narrow logarithmic divisor classes of degree 0 for number fields F. As an application, we compute in some cases the 2-rank of the wild kernel WK2(F)

Diseño de una prótesis de cadera utilizando materiales compuestos para permitir la movilidad en miembros inferiores

Los problemas de salud a la cadera en pacientes adulto mayor son mayormente ocasionados por fracturas de cadera intradomiciliarias y extradomiciliarias. Esto origina la pérdida de movilidad y en un porcentaje minoritario hasta la muerte. Por ello, es necesario el reemplazo a partir de una prótesis de cadera que tenga buena durabilidad y no tengan que ser cambiadas, produciendo dolor, malestar y en muchos casos la invalidez del paciente. Por ello el objetivo fue diseñar una prótesis de cadera utilizando materiales compuestos que tengan una buena resistencia, buena durabilidad y permitan la movilidad en miembros inferiores. Para ello, se evaluó el porcentaje de personas a partir de 50 años con problemas de salud a la cadera y se identificó que a partir de los 60 años las mujeres sufren fracturas tipo extracapsulares (zona 2 y 3). Así mismo, usando la metodología de diseño conceptual de Pahl y Beitz; Karl T. Ulrich y Steven D. Eppinger se logró un diseño que cumple con las necesidades y métricas que la paciente necesita. Por otro lado, utilizando el software CES EduPack se logró identificar opciones de materiales para el desarrollo de la prótesis, siendo el Ti-6Al-4V y la biocerámica de zirconia los materiales seleccionados. A partir de entrevistas y encuestas a especialistas se diseñó y simuló la prótesis en el programa SolidWorks, tomando en cuenta la norma ISO 7206-4. Los resultados estuvieron por debajo del límite elástico máximo de 9,10e+08 Pa y una vida total de 1,400e+08 ciclos, siendo valores favorables

Interpretable Sensitivity Analysis for Balancing Weights

Assessing sensitivity to unmeasured confounding is an important step in observational studies, which typically estimate effects under the assumption that all confounders are measured. In this paper, we develop a sensitivity analysis framework for balancing weights estimators, an increasingly popular approach that solves an optimization problem to obtain weights that directly minimizes covariate imbalance. In particular, we adapt a sensitivity analysis framework using the percentile bootstrap for a broad class of balancing weights estimators. We prove that the percentile bootstrap procedure can, with only minor modifications, yield valid confidence intervals for causal effects under restrictions on the level of unmeasured confounding. We also propose an amplification to allow for interpretable sensitivity parameters in the balancing weights framework. We illustrate our method through extensive real data examples

Estudio comparativo del comportamiento de diversos materiales de refuerzo en matrices de titanio fabricados mediante compactación por sinterización rápida

Regarding titanium matrix composites (TMCs), their properties strongly depend on the reinforcement material employed for their manufacturing; this may lead to a multitude of investigations on TMCs. Considering the diverse typology of the reinforcement, six types of ceramic particles were tested in this investigation: B₄C, SiB₆ , TiB₂ , TiC, TiN, and BN. In order to compare their behaviour and their own influence on the properties of the TMCs, the same ratio was employed in the starting materials, 30% volume. Among the techniques for developing TMCs, a significant number of authors propose Powder Metallurgy as a favourable route. In this framework, the novel Rapid Sinter Pressing technique was employed to perform the present study, due to its flexibility, repeatability, and reproducibility, as well as short-run cycle times. The processing temperature (930 °C) was set with the intention of evaluating how the reinforcements behave differently depending on their reactivity with the Ti matrix. In this regard, the main objective of the research was to carry out a comparison on the behaviour of seven TMCs fabricated with similar operational parameters via RSP.En cuanto a los materiales compuestos de base titanio (TMC), sus propiedades dependen en gran medida del material de refuerzo empleado para su fabricación; dando lugar a una gran diversidad de investigaciones sobre los TMCs. Considerando la diversa tipología del refuerzo, en este estudio se trabajó con seis tipos de partículas cerámicas: B₄C, SiB₆,TiB₂ , TiC, TiN y BN. Para poder comparar su comportamiento e influencia sobre las propiedades de los TMCs, se empleó siempre la misma proporción con respecto al material de partida, 30% en volumen. Entre las técnicas que se conocen para desarrollar TMCs, la pulvimetalurgia ha sido propuesta como una vía favorable por un número significativo de autores. En este marco, para la realización del presente estudio, se utilizó la novedosa técnica Rapid Sinter Pressing, debido a su flexibilidad, repetibilidad y reproducibilidad, así como a sus reducidos tiempos de ciclo. La temperatura de procesamiento (930 °C) se estableció con la intención de evaluar cómo los refuerzos afectan de diferente manera, en función de su reactividad con la matriz de Ti. En este sentido, el objetivo principal de esta investigación ha sido realizar una comparativa del comportamiento de siete TMCs fabricados vía de Compactación por Sinterización Rápida (Rapid Sinter Pressing) bajo las mismas condiciones de procesado.Universidad de Sevilla VI PPIT-2020-I.