Caracterización multianalítica de meteorito marciano NWA2975 mediante CF-LIBS, fluorescencia de rayos X y espectroscopía Raman

La caracterización isotópica y elemental de los meteoritos de Marte ha permitido determinar la cronología de los procesos de formación del planeta y avanzar en la comprensión de su evolución biogeoquímica e hidrológica. Los meteoritos más abundantes son las rocas de origen ígneo, como las shergottitas. Los estudios petrológicos y geoquímicos previos del meteorito Northwest Africa 2975 (NWA 2975), revelaron que se trata de una roca volcánica de grano medio, entre subofítica y granular, compuesta predominantemente por piroxenos (57,3 vol.%) y plagioclasa (38,3 vol. %) completamente enmascarados con fases opacas (2,7 vol.%) y fosfatos (1,7 vol.%) [1]. El instrumento SuperCam a bordo del rover Perseverance (misión MARS 2020 de la NASA) está equipado con técnicas atómicas y moleculares (incluyendo LIBS y Raman) para la detección y análisis a distancia de muestras geológicas en la superficie del Planeta Rojo. La capacidad de estas técnicas se ha demostrado ampliamente en la caracterización de rocas, minerales y suelos en varias misiones espaciales. En el presente trabajo, se analizó un fragmento del meteorito NWA 2975 mediante un sistema de micro-LIBS con el objetivo de revelar su composición química elemental. Debido a la heterogeneidad intrínseca de la muestra, se analizaron diferentes posiciones de su superficie. El análisis cuantitativo de los elementos principales (Si, Al, Fe, Mg, Mn, Ca y O) y de otros elementos menores se llevó a cabo utilizando la metodología Calibration-Free [2]. Los resultados sugieren la presencia de piroxenos como principal componente mineral en las posiciones inspeccionadas, aunque también se pueden encontrar otras fases minerales como la plagioclasa. La información extraída del análisis LIBS se ha comparado con la de fluorescencia de rayos X (XRF) y la espectroscopia Raman. El uso combinado de diferentes técnicas espectroscópicas ha permitido obtener una mejor interpretación de los resultados composicionales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Mexico-US Migration: Views from Both Sides of the Border

Migration to the United States increased sharply in the 1980s and 1990s, raising political concerns. The immigrant flow from Mexico, both authorized and unauthorized, was particularly large. Good data would con-tribute to rational discussion of this politically charged issue, but data on immigration, particularly of the unauthorized, are notoriously poor. This article applies residual estimation techniques to data from the 1990 and 2000 population censuses of Mexico and the United States (Mexico-born population) to quantify the intercensal migration flow, arguing that the reasons why unauthorized migrants might avoid enumeration in the United States would not adversely affect data from Mexico. Results suggest that the annual net flow of migrants aged 10 to 80 years from Mexico to the United States averaged between 324,000 and 440,000 between 1990 and 2000. A sensitivity analysis indicates that these results are quite robust (especially those using US data) to likely errors. Copyright 2005 The Population Council, Inc..

“I Feel Like More of a Man”: A Mixed Methods Study of Masculinity, Sexual Performance, and Circumcision for HIV Prevention

Ethnographic studies from numerous societies have documented the central role of male circumcision in conferring masculinity and preparing boys for adult male sexuality. Despite this link between masculinity, sexuality, and circumcision, there has been no research on these dynamics among men who have received a circumcision for HIV prevention. We employed a mixed methods approach with data collected from recently circumcised men in the Dominican Republic (DR) to explore this link. We analyzed survey data collected 6-12 months post-circumcision (N = 293) and in-depth interviews with a sub-sample of those men (n = 30). We found that 42% of men felt more masculine post-circumcision. In multivariate analysis, feeling more masculine was associated with greater concern about being perceived as masculine (OR = 1.70, 95% CI: 1.25-2.32), feeling more potent erections post-circumcision (OR = 2.25, 95% CI: 1.26-4.03), and reporting increased ability to satisfy their partner post-circumcision (OR = 2.30, 95% CI: 1.11-4.77). In qualitative interviews, these factors were all related to masculine norms of sexually satisfying one's partner and men's experiences of circumcision were shaped by social norms of masculinity. This study highlights that circumcision is not simply a biomedical intervention and that circumcision programs need to incorporate considerations of masculine norms and male sexuality into their programming