Analysis of internal ablation for the thermal control of aerospace vehicles

A new method of thermal protection for transatmospheric vehicles is introduced. The method involves the combination of radiation, ablation and transpiration cooling. By placing an ablating material behind a fixed-shape, porous outer shield, the effectiveness of transpiration cooling is made possible while retaining the simplicity of a passive mechanism. A simplified one-dimensional approach is used to derive the governing equations. Reduction of these equations to non-dimensional form yields two parameters which characterize the thermal protection effectiveness of the shield and ablator combination for a given trajectory. The non-dimensional equations are solved numerically for a sample trajectory corresponding to glide re-entry. Four typical ablators are tested and compared with results obtained by using the thermal properties of water. For the present level of analysis, the numerical computations adequately support the analytical model

Selection-bias correction based on the multinomial logit: An application to the Mexican labor market

In this presentation, we illustrate an application of a relatively new selection-bias correction methodology based on the multinomial logit model using the selmlog Stata command (Bourguignon, Fournier, and Gurgand, 2007, Journal of Economic Surveys 21: 174–205). selmlog allows for getting both consistent and efficient estimates of the selection process and a fairly good correction for the outcome equation, even when the independence of irrelevant alternatives (IIA) assumption is not achieved. The exercise depicts the current pattern of the occupational choices for the individuals in the Mexican labor market using a longitudinal panel with microdata from the Encuesta Nacional de Ocupación y Empleo (ENOE) during February 2008 to March 2009. We estimate an equation over an endogenously selected population. The command grants simplicity for both distributional and IIA assumptions for parametric models.

Death as a presence in the work of Griselda Alvarez

La literatura de Jalisco pocas veces considera la obra poética de Griselda Álvarez (Guadalajara, 1913), debido a que su actuar público la relaciona con el estado mexicano de Colima, del cual fue gobernadora entre los años 1979-1985. Estas páginas realizan un seguimiento retórico al tópico de la muerte en sus versos, desde los análisis del discurso y de contenido, temática no considerada hasta el momento en estudios previos; considera el seguimiento de los seis primeros títulos de su producción, por ser éstos anteriores a su gestión pública, tiempo sin ataduras para el ofrecimiento de un discurso social con mayor libertad expresiva. Es pertinente aclarar que durante su ejercicio en el poder, Álvarez no escribió título alguno. La notoriedad de Griselda Álvarez como poeta había alcanzado algunas cimas antes de su gubernatura, como lo confirman los libros Anatomía superficial y Estación sin nombre. La escritora se distinguió por utilizar el formato del soneto, así como el tema erótico en su trabajo. La muerte, de acuerdo con la taxonomía de Merlin H. Forster, es una presencia viva en su verso, y la argumentación el arma retórica de su preferencia

Verdad ilustrada, contra las imposturas, que ha escrito el R.P.Fr. Marcos de Alcalá, en la Chrónica nuevamente impressa en Madrid, de S. Pedro de Alcántara

Sign.: [calderón]4, A-B4, C2.Port. orlada

La pobreza urbana y rural en México y Sonora: impacto de Oportunidades en los primeros años de aplicación, 2002-2006

La pobreza se define con base en el enfoque monetario y se estima con el método de líneas de pobreza (Foster, Greer y Thoerbecke, 1984; Sen, 1976); luego, se recurre a la técnica de microsimulación estática (Bourguignon y Spadaro, 2006) para captar el impacto del programa Oportunidades en la disminución de la pobreza en el sector urbano y rural de México y Sonora. Se encontró un impacto muy limitado en la reducción de la pobreza, lo que se debe a la insuficiencia de recursos asignados al programa y a la exclusión de hogares en pobreza; sin embargo, mientras el impacto nacional fue ligeramente mayor en el sector rural, Sonora observó uno heterogéneo, ya que el sector urbano redujo más la pobreza alimentaria y el rural la pobreza patrimonial. La información proviene de la Encuesta Nacional de Ingresos y Gastos de los Hogares 2002 y 2006

The Mexican Labor Market, 1992-2002: A Counterfactual Analysis of changes in the Informal Sector

This research presents empirical evidence of the mexican labor market earnings for males and females, pooling together a set of occupational categories into formal and informal workers using the counterfactual technique of Dinardo, Fortin and Lemiux (1996). The semi-parametric specification allows visualizing the earnings distribution according to the decomposition of subgroups and occupational process using a logistic model. We find that informal self-employment is better paid for men than for their counterpart between 1992 and 2002, meanwhile women seem to be better positioned as formal salaried than men. Counterfactuals predict an improvement for both informal women and males, had they decided to become formal workers and with the same attributes in 2002; an opposite trend was found for the initial year. This situation remains at odds when depicting predicted multinomial probabilities, as informal workers tend to develop entrepreneurial activities as long as they acquire more experience.occupational choice, earnings, labor market, distribution, formal and informal sector.

Effects of Spaceflight on Human Induced Pluripotent Stem Cell-Derived Cardiomyocyte Structure and Function.

With extended stays aboard the International Space Station (ISS) becoming commonplace, there is a need to better understand the effects of microgravity on cardiac function. We utilized human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to study the effects of microgravity on cell-level cardiac function and gene expression. The hiPSC-CMs were cultured aboard the ISS for 5.5 weeks and their gene expression, structure, and functions were compared with ground control hiPSC-CMs. Exposure to microgravity on the ISS caused alterations in hiPSC-CM calcium handling. RNA-sequencing analysis demonstrated that 2,635 genes were differentially expressed among flight, post-flight, and ground control samples, including genes involved in mitochondrial metabolism. This study represents the first use of hiPSC technology to model the effects of spaceflight on human cardiomyocyte structure and function

Is the Economic Convergence of the Mexican States Possible? Estimates for the 1940-2013 Period

In this paper we study β-convergence: absolute and conditional, also sigma convergence, using cross-state regression models, based in a long term period of time for the Federated States of Mexico. When absolute convergence is estimated (Solow Model, 1956) we found the negative sign expected but the result is not statistically reliable; while, estimates for decades only show absolute convergence for the period of 1960-1970, known with the term of "Mexican Miracle", a third regression including population growth rate and physical capital investment per capita, variables as considered by Solow models, confirm that there is not absolute convergence like the first result obtained. The estimate including human capital index (HCI) and human development index (HDI 2), shows a number of outliers, suggesting the introduction of proxy variables which capture the political effects and explore conditional convergence. When panel heteroskedastic is considerate, convergence is observed, but β 2% any case was estimated

Self-assembly of hexahistidine-tagged tobacco etch virus capsid protein into microfilaments that induce IgG2-specific response against a soluble porcine reproductive and respiratory syndrome virus chimeric protein

Antibody titers produced in sera of immunized mice recognizing His-TEV-CP protein. Immunization and ELISA procedures were conducted as described in Fig. 3 legend. Briefly explained, serum samples corresponding to bleeding 3 of mice group immunized with 25 μg of TEV VLPs (TEVVLPs25) were tested for total IgG and isotypes IgG1, IgG2a and IgG2b antibody response by ELISA in plates coated with with 1 μg of His-TEV-CP protein per well. Absorbance was taken at 450 nm in xMark spectrophotometer microplate reader (BioRad, USA). Results are expressed as antibody endpont titers greater than threefold the background value of preimmune sera. Excel was used for data processing. (TIFF 1142 kb