Evidencias geol\uf3gicas, geomorfol\uf3gicas y geof\uedsicas de deformaci\uf3n asociada a la falla Cerritos y su implicaci\uf3n en el peligro s\uedsmico de Morelia, Michoac\ue1n, M\ue9xico

The Cerritos fault is located SW of Morelia city, in the state of Michoac\ue1n, M\ue9xico. The fault belongs to the western part of the Morelia-Acambay Fault System, an area with several active segmented faults that form various grabens and half-grabens. In this area, faulting affects Miocene to Holocene lithologies; some of these faults even control the distribution of regional monogenetic volcanoes. This work is an interdisciplinary approach to characterize the Cerritos fault, an important structure with a high seismic hazard potential. The Cerritos fault is a 12 km-long oblique fault (normal-left lateral) with a 130\ub15 m-high topographic relief (100 m of surface displacement + 30 m of subsurface displacement estimated from the inverted resistivity study). This fault is ENE-WSW oriented (255\ub0), with a 76\ub0 NNW dip. In a well\u2010exposed cross section of the Cerritos fault, a few meters from the master fault trace, a colluvial wedge with organic material was identified, yielding a radiocarbon age of 3.37-3.21 cal ka BP. Our geologic and geomorphological analyses indicate that the Cerritos fault is a young, tectonically-active fault, especially in its eastern part. The vertical and horizontal linearity of the fault scarp and the accumulation of lake deposits in the down-thrown block suggest active vertical motion (uplift and subsidence, respectively) along this fault. Geophysical surveys, including seismic refraction, terrestrial magnetometry, and electrical resistivity tomography, show the subsurface geometry of the fault to be characterized by a main listric fault plane and a damage zone in the footwall block, extending as far as 75 m from the main scarp. The damage zone is characterized by secondary, synthetic, and antithetic faults, forming roll-over anticlines and two crestal collapse grabens that accumulate colluvial material. Paleoseismic estimates of activity and seismic hazard potential indicate that the Cerritos fault has a slip-rate of 0.03\ub10.01 mm/yr, with mean vertical displacements of 0.5 m per event and a mean recurrence interval of 16 700 years. The Cerritos fault can generate single-segment ruptures with magnitudes of MW 6.2 to 6.6. Still, in a worst-case scenario, it could also rupture with the subparallel and adjacent Morelia and Cointzio faults, generating earthquake magnitudes up to MW 6.9

Diversidad de ma\uedz en la sierra sur de Oaxaca, M\ue9xico: conocimiento y manejo tradicional

The state of Oaxaca represents an important pool of maize in Mexico. Previous studies have indicated the presence of many local varieties and agronomic races, mainly at the Northern Sierra and Central Valleys. The Southern Sierra has not been studied, in spite of the presence of indigenous Zapotec communities, which cultivate maize, among other crops, and have preserved local varieties. The present study is focused on the following questions: Which is the maize diversity, in terms of traditional varieties and agronomic races, in the Zapotec region of Los Loxicha? Does Maize diversity follow a pattern of distribution along an altitudinal interval? Which practices promote, and maintain this diversity? To answer these questions, we conducted a study within five municipalities at the Southern part of Oaxaca. During 2007, structured interviews were applied to 930 farmers in order to obtain a descriptive process of seed management. Morphological characterization of agronomic races was based on ear specimens obtained from a sample of 375 "milpas", with 20 plants per "milpa". High levels of local maize diversity were recorder, with 36 traditional varieties belonging to 10 races. Races exhibited differences in terms of phenotypic variation, and altitudinal distribution, and some could indicate local adaptation. People practice some ancestral management of ear and seed selection, thus maintaining differentiation among varieties and agronomic races. Nevertheless, sowing many local varieties in the same field, promotes gene flow and introgression among them, maintaining, and promoting phenotypic and genetic diversity.El estado de Oaxaca representa un importante acervo de maíz en México. Estudios previos han indicado la presencia de muchas variedades locales y razas agronómicas en la Sierra Norte y Valles Centrales. La Sierra Sur ha sido poco estudiada a pesar de la presencia de comunidades indígenas zapotecas, las cuales cultivan maíz, entre otras especies, y han preservado las variedades locales. El presente estudio responde a las siguientes preguntas: ¿cuál es la diversidad de maíz en términos de variedades tradicionales y razas agronómicas en la región zapoteca de Los Loxicha?, ¿la diversidad de maíz sigue un patrón de distribución a lo largo de un gradiente altitudinal?, ¿cuáles prácticas promueven y mantienen esta diversidad? Para contestar estas preguntas se realizó un estudio en cinco municipios de la Sierra Sur de Oaxaca. Durante 2007 se aplicaron entrevistas estructuradas a 930 agricultores para describir el proceso de manejo de semilla. La caracterización morfológica de las razas agronómicas se basó en muestras de mazorcas obtenidas en 375 milpas, con 20 plantas por milpa. Se encontraron altos niveles de diversidad local de maíz, con 36 variedades tradicionales correspondientes a 10 razas agronómicas. Las razas exhibieron diferencias en términos de variación fenotípica, distribución altitudinal y algunas muestran adaptación local. Los agricultores practican algunas formas de manejo ancestral para la selección de mazorcas y semillas, manteniendo, así, ciertos niveles de diferenciación entre las variedades y las razas agronómicas. Sin embargo, al sembrar diferentes variedades dentro de la misma parcela, se promueve el flujo génico y la introgresión entre ellas, manteniendo y promoviendo la diversidad fenotípica y genética

Reduced Cancer Incidence in Huntington's Disease: Analysis in the Registry Study

Background: People with Huntington's disease (HD) have been observed to have lower rates of cancers. Objective: To investigate the relationship between age of onset of HD, CAG repeat length, and cancer diagnosis. Methods: Data were obtained from the European Huntington's disease network REGISTRY study for 6540 subjects. Population cancer incidence was ascertained from the GLOBOCAN database to obtain standardised incidence ratios of cancers in the REGISTRY subjects. Results: 173/6528 HD REGISTRY subjects had had a cancer diagnosis. The age-standardised incidence rate of all cancers in the REGISTRY HD population was 0.26 (CI 0.22-0.30). Individual cancers showed a lower age-standardised incidence rate compared with the control population with prostate and colorectal cancers showing the lowest rates. There was no effect of CAG length on the likelihood of cancer, but a cancer diagnosis within the last year was associated with a greatly increased rate of HD onset (Hazard Ratio 18.94, p < 0.001). Conclusions: Cancer is less common than expected in the HD population, confirming previous reports. However, this does not appear to be related to CAG length in HTT. A recent diagnosis of cancer increases the risk of HD onset at any age, likely due to increased investigation following a cancer diagnosis