Constraints from finite element modeling on the active tectonics of northern Central America and the Middle America Trench

We have developed an elastic finite element model in order to study the role of the different forces acting on the northwestern part of the Central American Volcanic Arc and the Chortis Block. We present synthetic focal mechanisms, maps of tectonic regime, and strain crosses to analyze the results. The models show that to achieve the observed state of stress on the volcanic arc, the arc must be modeled as a lithospheric weak zone. Also, the forces related to the eastward drift of the Caribbean plate must be higher than those related to the subduction of the Cocos plate. The coupling on the subduction interface must be low, with or without slip-partitioning due to the obliquity of the subduction at the trench. At Guatemala the western edge of the Chortis block is pinned against North America, even with low trench-normal forces, making the triple junction between the Cocos, North American, and Caribbean plates a zone of diffuse deformation. The extension in the western part of the Chortis block, from Guatemala to the Honduras depression, is explained by the geometry of the North American-Caribbean plate boundary and the direction of motion of the Caribbean plate with respect to North America. The direction of extension in the Chortis block is always E-W regardless of the magnitude of the applied forces, and the main part of the deformation is absorbed between the Ipala graben and the Honduras depression, both features being consistent with our models.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEMinisterio de Educación y Cienciapu

Angular distributions of protons scattered by 40 Ar nuclei with excitation of the 2 + (1.46 MeV) and 3 − (3.68 MeV) collective levels for incident energies of 25.1, 32.5, and 40.7 MeV

Elastic and inelastic scattering of unpolarized and polarized protons by 40Ar nuclei for incident energies between 20 and 50 MeV has been studied by reanalyzing experimental scattering spectra for the 2+(1.46 MeV) and 3-(3.68 MeV) levels in the angular range 30º–160º for incident protons of energies of 25.1, 32.5, and 40.7 MeV. An isospin dependent soft-rotator coupled-channels optical model with the potential containing a dispersive term with a nonlocal contribution is used to analyze the data

Evaluación en campo de la resistencia de líneas transgénicas de ciruelo europeo (Prunus domestica L.) a Plum pox virus

La sharka es la enfermedad viral más grave de frutales de hueso. Afecta especialmente a albaricoquero, melocotonero y ciruelo produciendo deformación, pérdida de calidad y caída prematura de los frutos. Esto causa importantes pérdidas económicas en la industria de frutales de hueso. El agente causante de la sharka es Plum pox virus (PPV). PPV se transmite a través de pulgones y mediante injerto, siendo el transporte y uso ilegal de material infectado la principal causa de la dispersión de la enfermedad a larga distancia. Existen programas de mejora encaminados a la obtención de variedades de prunus resistentes a PPV. Sin embargo, el largo tiempo que requiere esta técnica unido a la naturaleza poligénica de la resistencia y a la falta de fuentes de resistencia compatibles han hecho que se obtengan escasos éxitos y únicamente en albaricoquero. Una técnica alternativa o complementaria es el uso de la resistencia derivada del patógeno (PDR) mediante la obtención de plantas transgénicas que expresan un gen viral. Esto confiere a la planta resistencia frente al virus del cual procede el gen y frente a virus relacionados. En este sentido, Scorza et al. (1994) obtuvieron líneas de ciruelo europeo (Prunus domestica L.) que expresan el gen de la proteína de la cápsida de PPV. En condiciones de invernadero estas líneas transgénicas mostraron distintos grados de sensibilidad a la infección por PPV, con excepción de la línea C5 que demostró ser altamente resistente a la infección natural (a través de pulgones) de PPV. Cuando las plantas CS se inocularon mediante injerto, se desarrolló una infección muy leve y sólo en zonas localizadas de las plantas

La Sharka tipo Marcus (M), una grave enfermedad del melocotonero

Plum pox virus (PPV) causa la enfermedad de la sharka en frutales de hueso. Se trata de la enfermedad viral más grave del albaricoquero y ciruelo y también del melocotonero, cuando están presentes ciertos aislados del virus denominados Marcus (M) o tipos recombinantes con M (Rec). En España sólo se han dispersado aislados comunes o D del virus, pero existe riesgo real de introducción de aislados M agresivos en melocotonero, que podrían incidir gravemente en la producción temprana española. De hecho, un foco de PPV-M fue detectado y erradicado en Aragón en 2002. Los aislados Marcus se están dispersando por la cuenca del Mediterráneo y tienen una incidencia importante en ltalia y Francia, países con los que se mantiene un frecuente tráfico de material vegetal. La precaución y la vigilancia de fruticultores, viveristas y técnicos, debiera poderevitarla introducción y dispersión de aislados agresivos PPV-M en España. Se dispone técnicamente de sistemas de diagnóstico específicos que permiten la detección específica de cepas Marcus de forma fiable. Estos métodos, disponibles comercialmente, han sido transferidos a los Servicios de Sanidad Vegetal de las distintas Comunidades Autónomas

Concentration of electric dipole strength below the neutron separation energy in N = 82 nuclei

The semi-magic nuclei Ba-138, Ce-140, and Sm-144 have been investigated in photon scattering experiments up to an excitation energy of about 10 MeV. The distribution of the electric dipole strength shows a resonance like structure at energies between 5.5 and 8 MeV exhausting up to 1% of the isovector E1 Energy Weighted Sum Rule.Comment: 10 pages, 3 figure

Patterns of homozygosity in insular and continental goat breeds

Background: Genetic isolation of breeds may result in a significant loss of diversity and have consequences on health and performance. In this study, we examined the effect of geographic isolation on caprine genetic diversity patterns by genotyping 480 individuals from 25 European and African breeds with the Goat SNP50 BeadChip and comparing patterns of homozygosity of insular and nearby continental breeds. Results: Among the breeds analysed, number and total length of ROH varied considerably and depending on breeds, ROH could cover a substantial fraction of the genome (up to 1.6 Gb in Icelandic goats). When compared with their continental counterparts, goats from Iceland, Madagascar, La Palma and Ireland (Bilberry and Arran) displayed a significant increase in ROH coverage, ROH number and F ROH values (P value < 0.05). Goats from Mediterranean islands represent a more complex case because certain populations displayed a significantly increased level of homozygosity (e.g. Girgentana) and others did not (e.g. Corse and Sarda). Correlations of number and total length of ROH for insular goat populations with the distance between islands and the nearest continental locations revealed an effect of extremely long distances on the patterns of homozygosity. Conclusions: These results indicate that the effects of insularization on the patterns of homozygosity are variable. Goats raised in Madagascar, Iceland, Ireland (Bilberry and Arran) and La Palma, show high levels of homozygosity, whereas those bred in Mediterranean islands display patterns of homozygosity that are similar to those found in continental populations. These results indicate that the diversity of insular goat populations is modulated by multiple factors such as geographic distribution, population size, demographic history, trading and breed management

Field trials of plum clones transformed with the Plum pox virus coat protein (PPV-CP) gene

Transgenic clones C2, C3, C4, C5, C6, and PT-6, of plum (Prunus domestica L.) transformed with the coat protein (CP) gene of Plum pox virus (PPV), PT-23 transformed with marker genes only, and nontransgenic B70146 were evaluated for sharka resistance under high infection pressure in field trials in Poland and Spain. These sites differed in climatic conditions and virus isolates. Transgenic clone C5 showed high resistance to PPV at both sites. None of the C5 trees became naturally infected by aphids during seven (Spain) or eight (Poland) years of the test, although up to 100% of other plum trees (transgenic clones and nontransgenic control plants) grown in the same conditions showed disease symptoms and tested positively for PPV. Although highly resistant, C5 trees could be infected artificially by chip budding or via susceptible rootstock. Infected C5 trees showed only a few mild symptoms on single, isolated shoots, even up to 8 years post inoculation. These results clearly indicate the long-term nature and high level of resistance to PPV obtained through genetically engineered resistance

Development of covariance capabilities in EMPIRE code

The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model