Detrás del “país de las oportunidades”: Estrategias femeninas ante la transnacionalización de la comunidad campesina de Usibamba entre Perú y Estados Unidos

Usibamba, al día de hoy, es una comunidad transnacional(izada), cuyos procesos expansivos de la diáspora podrían rastrearse, en gran medida, a partir de la implementación de programas de exportación de mano de obra “barata” (o precarizada) desde las últimas décadas del siglo pasado (Paerregaard, 2005; Gilvonio, 2009; Altamirano, 2010 y otros) hacia ranchos ganaderos estadounidenses. La presente investigación tiene como propósito indagar en las estrategias de las mujeres de la comunidad campesina ante este proceso histórico y fenómeno que lleva más de 50 años de existencia. Ya que son los hombres, padres y esposos, quienes han sido reclutados para estos grandes ranchos, las mujeres han tenido que quedarse a cargo de muchos aspectos de la vida productiva y reproductiva de sus unidades domésticas (así como de la comunidad campesina). A partir de los enfoques de migración transnacional y nueva ruralidad, la teoría de reproducción social en la globalización y el empleo del concepto de estrategias femeninas; así como la aplicación de una etnografía multilocal entre Usibamba (Junín, Perú) y Bakersfield (California, Estados Unidos); y, finalmente, del análisis de ocho casos de mujeres, hemos podido dar cuenta de cuatro tipos de estrategias enmarcadas en un complejo proceso de transnacionalización de las unidades domésticas. Estas son: estrategias de sostenimiento familiar, de circulación de cuidados, de diversificación de ingresos y de desarrollo profesional. El trabajo de las mujeres ha permitido el sostenimiento de la vida comunal por años y sus estrategias se orientan a la reproducción de sus hogares en circunstancias adversas, así como la mejora de sus condiciones de vida y la de sus familias.Usibamba, today, is a transnational(ized) peasant community, which it’s expansive processes of diaspora could be traced, to a large extent, to the implementation of programs for the export of “cheap” (or precarised) labor since the last decades of the last century (Paerregaard, 2005; Gilvonio, 2009; Altamirano, 2010 and others) to U.S. cattle ranches. The purpose of this research is to investigate the strategies of women in the peasant community in the face of this historical process and phenomenon that has been going on for more than 50 years. Since it’s been the men, fathers and husbands, the ones who have been recruited for these large ranches, most women have had to remain in charge of many aspects of the productive and reproductive life of their domestic units (as well as of the peasant community). Based on the approaches of transnational migration and new rurality, the theories of social reproduction in globalization and the use of the concept of feminine strategies; as well as the application of a multilocal ethnography between Usibamba (Junín, Peru) and Bakersfield (California, United States); and, finally, the analysis of eight cases of women, we have been able to account for four types of strategies framed in a complex process of transnationalization of the households. These are: family support, circulation of care, income diversification and professional development strategies. Women's work has sustained communal life for years and their strategies are aimed at reproducing their households in adverse circumstances, as well as improving their living conditions and those of their families

Quasiparticle Interference on the Surface of Topological Crystalline Insulator Pb(1-x)Sn(x)Se

Topological crystalline insulators represent a novel topological phase of matter in which the surface states are protected by discrete point group-symmetries of the underlying lattice. Rock-salt lead-tin-selenide alloy is one possible realization of this phase which undergoes a topological phase transition upon changing the lead content. We used scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES) to probe the surface states on (001) Pb$_{1-x}$Sn$_{x}$Se in the topologically non-trivial (x=0.23) and topologically trivial (x=0) phases. We observed quasiparticle interference with STM on the surface of the topological crystalline insulator and demonstrated that the measured interference can be understood from ARPES studies and a simple band structure model. Furthermore, our findings support the fact that Pb$_{0.77}$Sn$_{0.23}$Se and PbSe have different topological nature.Comment: 5 pages, 4 figure

Papel del estrés en la intensidad de los síntomas SII

Irritable bowel syndrome is regarded as a biopsychosocial disorder, the result of a complex combination of predisposing, precipitating and perpetuating factors. Personality traits, affective status and stress are some of the relevant factors contributing to lower quality of life and symptom exacerbation in IBS patients. In order to examine the role of stress in IBS symptom exacerbation, the aims of this study were to explore the relationship of daily stressful events and symptom severity in a prospective manner and to explore the roles of neuroticism, anxiety, depression and stress in the vicious circle of symptom perpetuation. A total of 49 patients with IBS reported their symptom severity and daily stressful events intensity each day for 14 consecutive days. They also completed the Big five personality inventory, the Beck Depression Inventory and the State-trait anxiety inventory. Cross-correlation analyses were performed on the time series data for daily stress and symptom severity for each participant separately. Four different patterns of relationships were found in different subgroups of participants: positive cross-correlations of symptom severity and stress intensity on the same day; higher symptom severity on days following stressful days; lower symptom severity on days following stressful days; and lower stress intensity on days following severe symptoms. Using average scores for daily stress and symptom severity, as well as scores for neuroticism, anxiety and depression, we performed a path analysis to test a model of symptom exacerbation. It showed that, on the group level, average stress intensity predicts average symptom severity. Neuroticism and anxiety were not significant predictors of symptom severity, while depression showed a marginally significant relationship with symptom severity, mediated by stress intensity. In conclusion, depression and daily stress seem to be important contributors to the vicious circle of IBS symptom perpetuation.Síndrome del intestino irritable se considera un trastorno biopsicosocial, el resultado de la combinación compleja de factores predisponentes, precipitantes y perpetuos. Rasgos de personalidad, estado afectivo y estrés son algunos de los factores relevantes que contribuyen a la calidad de vida más baja y la exacerbación sintomática de los pacientes con SII. Para examinar el papel del estrés en la exacerbación sintomática de SII, el objetivo de este estudio era explorar la relación entre los acontecimientos cotidianos estresantes y la intensidad de los síntomas de forma prospectiva, tanto como explorar los papeles del neuroticismo, ansiedad, depresión y estrés en el círculo vicioso de perpetuación de los síntomas. Todos los 49 pacientes con SII informaron sobre la intensidad de los síntomas y la intensidad de los acontecimientos cotidianos estresantes cada día durante 14 días consecutivos. Además, completaron el Test de personalidad de los cinco grandes, Inventario de depresión de Beck e Inventario de ansiedad estado-rasgo. En los datos de series temporales se hizo el análisis de correlación cruzada para la intensidad del estrés diario y de los síntomas para cada participante por separado. Se encontraron cuatro patrones de relación diferentes en diferentes subgrupos de participantes: correlación cruzada positiva de la intensidad de los síntomas y del estrés el mismo día; intensidad de los síntomas más alta en los días después de los días estresantes; intensidad de los síntomas más baja en los días después de los días estresantes e intensidad del estrés más baja en los días después de los síntomas graves. Usando resultados promedios para el estrés diario y la intensidad de los síntomas, tanto como resultados para el neuroticismo, ansiedad y depresión, realizamos un análisis del camino para examinar el modelo de la exacerbación de los síntomas. Mostró que, al nivel de grupo, la intensidad del estrés promedia predice la intensidad de los síntomas promedia. Neuroticismo y ansiedad no eran predictores significativos de la intensidad de los síntomas, mientras que la depresión demostró una relación marginalmente significante con la intensidad de los síntomas, mediada por la intensidad del estrés. En conclusión, la depresión y el estrés diario parecen ser contribuidores importantes al círculo vicioso de la perpetuación de los síntomas SII

The mechanism of caesium intercalation of graphene

Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene can be manipulated by inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers, but the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali-atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also play a role for intercalation of layered materials.Comment: 8 pages, 7 figures in published form, supplementary information availabl

A New Magnetic Topological Quantum Material Candidate by Design

Magnetism, when combined with an unconventional electronic band structure, can give rise to forefront electronic properties such as the quantum anomalous Hall effect, axion electrodynamics, and Majorana fermions. Here we report the characterization of high-quality crystals of EuSn$_2$P$_2$, a new quantum material specifically designed to engender unconventional electronic states plus magnetism. EuSn$_2$P$_2$ has a layered, Bi$_2$Te$_3$-type structure. Ferromagnetic interactions dominate the Curie-Weiss susceptibility, but a transition to antiferromagnetic ordering occurs near 30 K. Neutron diffraction reveals that this is due to two-dimensional ferromagnetic spin alignment within individual Eu layers and antiferromagnetic alignment between layers - this magnetic state surrounds the Sn-P layers at low temperatures. The bulk electrical resistivity is sensitive to the magnetism. Electronic structure calculations reveal that EuSn$_2$P$_2$ might be a strong topological insulator, which can be a new magnetic topological quantum material (MTQM) candidate. The calculations show that surface states should be present, and they are indeed observed by ARPES measurements.Comment: 30 page, 12 figure

Realization of a Type‐II Nodal‐Line Semimetal in Mg3Bi2

Nodal-line semimetals (NLSs) represent a new type of topological semimetallic phase beyond Weyl and Dirac semimetals in the sense that they host closed loops or open curves of band degeneracies in the Brillouin zone. Parallel to the classification of type-I and type-II Weyl semimetals, there are two types of NLSs. The type-I NLS phase has been proposed and realized in many compounds, whereas the exotic type-II NLS phase that strongly violates Lorentz symmetry has remained elusive. First-principles calculations show that Mg3Bi2 is a material candidate for the type-II NLS. The band crossing is close to the Fermi level and exhibits the type-II nature of the nodal line in this material. Spin-orbit coupling generates only a small energy gap (≈35 meV) at the nodal points and does not negate the band dispersion of Mg3Bi2 that yields the type-II nodal line. Based on this prediction, Mg3Bi2 single crystals are synthesized and the presence of the type-II nodal lines in the material is confirmed. The angle-resolved photoemission spectroscopy measurements agree well with the first-principles results below the Fermi level and thus strongly suggest Mg3Bi2 as an ideal material platform for studying the as-yet unstudied properties of type-II nodal-line semimetals