The Destruction of 3He by Rayleigh-Taylor Instability on the First Giant Branch

Low-mass stars, ~1-2 solar masses, near the Main Sequence are efficient at producing 3He, which they mix into the convective envelope on the giant branch and distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the observed cosmic abundance of 3He with the predictions of Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell. In this zone the burning of the 3He left behind by the retreating convective envelope is predominantly by the reaction 3He + 3He -> 4He + 2p, a reaction which, untypically for stellar nuclear reactions, {\it lowers} the mean molecular weight, leading to a local minimum. This local minimum leads to Rayleigh-Taylor instability, and turbulent motion is generated which will continue ultimately up into the normal convective envelope. Consequently material from the envelope is dragged down sufficiently close to the burning shell that the 3He in it is progressively destroyed. Thus we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He. Some slow mixing mechanism has long been suspected, that connects the convective envelope of a red giant to the burning shell. It appears to be necessary to account for progressive changes in the 12C/13C and 14N/12C ratios on the First Giant Branch. We suggest that these phenomena are also due to the Rayleigh-Taylor-unstable character of the 3He-burning region.Comment: Paper presented at IAU-GA, Prague, August 200

Pif1-Family helicases support fork convergence during DNA replication termination in eukaryotes

The convergence of two DNA replication forks creates unique problems during DNA replication termination. In E. coli and SV40, the release of torsional strain by type II topoisomerases is critical for converging replisomes to complete DNA synthesis, but the pathways that mediate fork convergence in eukaryotes are unknown. We studied the convergence of reconstituted yeast replication forks that include all core replisome components and both type I and type II topoisomerases. We found that most converging forks stall at a very late stage, indicating a role for additional factors. We showed that the Pif1 and Rrm3 DNA helicases promote efficient fork convergence and completion of DNA synthesis, even in the absence of type II topoisomerase. Furthermore, Rrm3 and Pif1 are also important for termination of plasmid DNA replication in vivo. These findings identify a eukaryotic pathway for DNA replication termination that is distinct from previously characterized prokaryotic mechanisms

How does Extrusion Technology Help the Development of Foods with Better Nutritional Value?

Mini review

Adaptive refinement and selection process through defect localization for reconstructing an inhomogeneous refraction index

We consider the iterative reconstruction of both the internal geometry and the values of an inhomogeneous acoustic refraction index through a piecewise constant approximation. In this context, we propose two enhancements intended to reduce the number of parameters to reconstruct, while preserving accuracy. This is achieved through the use of geometrical informations obtained from a previously developed defect localization method. The first enhancement consists in a preliminary selection of relevant parameters, while the second one is an adaptive refinement to enhance precision with a low number of parameters. Each of them is numerically illustrated

Retroauricular dermoid cyst associated with Gorlin syndrome. A case report

Background Gorlin syndrome is an autosomal dominant genodermatosis characterized by the early appearance of multiple basal cell carcinomas, odontogenic keratocysts and skeletal abnormalities. It is caused by mutations in the hedgehog signalling pathway, primarily in the tumour suppressor gene PTCH1 (9q22.1-q31). Case summary We present a 14-year-old girl who consulted for asymmetrical ears, in the context of multiple disorders such as mental retardation, snoring, non-specific coagulation abnormalities, retrognathia, pectus excavatum and scaphoid duplication. During the intervention, a retroauricular cystic tumour was found incidentally, reported by Pathology as a dermoid cyst. The syndrome is confirmed by a genetic study with the result of a new pathological variant in PTCH1. Conclusion We describe the coexistence of this entity with a dermoid cyst. Furthermore, it is exceptional in its retroauricular location and the pathological point mutation in the PTCH1 gene, consisting of the pCys56Gly variant

Temperatura ambiental y su efecto sobre parámetros fisiológicos en vacas Nellore y cruces bajo condiciones del trópico peruano

The aim of this study was to determine the physiological parameters related to body thermoregulation, as well as basic haematological parameters between Nellore cows and crossbreeds under heat stress. The study was carried out in the province of Satipo, Junín region, Peru, at 628 meters above sea level. Sixteen crossbred cows (Brown Swiss x Nellore) and 16 Nellore cows were used. The physiological parameters (body temperature, respiratory rate and heart rate) were evaluated in the morning (06:00-07:00) and in the afternoon (14:00-17:00). Blood samples were taken to determine haemoglobin (g/dl), haematocrit (%), mean corpuscular volume (MCV, fl), mean corpuscular haemoglobin (MCH, pg), mean corpuscular haemoglobin concentration (MCHC, g/dl). Thermoregulatory functions (rectal temperature, heart rate and respiratory rate) were affected during hours of heat stress in both racial groups (p<0.05). Haematological values were found within the referential ranges, except the MCV and MCH.El objetivo del estudio fue determinar las constantes fisiológicas relacionadas con la termorregulación corporal, así como parámetros hematológicos básicos entre vacas Nellore y sus cruces bajo estrés calórico. El estudio se desarrolló en la provincia de Satipo, región Junín, Perú, a 628 msnm. Se trabajó con 16 vacas cruzadas (Brown Swiss x Nellore) y 16 vacas Nellore. Las constantes fisiológicas (temperatura corporal, frecuencia respiratoria y frecuencia cardiaca) se evaluaron en horas de la mañana (06:00-07:00) y en la tarde (14:00-17:00). Se tomaron muestras de sangre para determinar hemoglobina (g/dl), hematocrito (%), volumen corpuscular medio (VCM, fl), hemoglobina corpuscular media (HCM, pg), concentración de hemoglobina corpuscular media (CHCM, g/dl). Las funciones termorreguladoras (temperatura rectal, frecuencia cardiaca y frecuencia respiratoria) se vieron afectadas en horas de estrés calórico en los dos grupos raciales (p<0.05). Los valores hematológicos se encontraron dentro de los rangos referenciales, excepto el VCM y la HCM

Situational diagnostic of the breeding of guinea pigs in Cajamarca

Se realizó una encuesta en julio de 2004 a 160 familias criadoras de cuyes en el distrito de Santa Cruz, Cajamarca, con el objetivo de caracterizar los sistemas de producción de cuyes. El 44.6% de los productores tenía más de 50 años de edad y el 42% de las esposas tenía entre 31 a 50 años. Primaria era el grado de instrucción predominante. La ocupación del jefe de familia era la agricultura (95.4%) y de la esposa era su casa (97.2%). La crianza de cuyes era conducida por el ama de casa bajo un sistema familiar o tradicional. Se encontró un promedio de 20.4 cuyes por familia, criados en un solo grupo sin distinción de clase, sexo y edad, de preferencia en la cocina (88.8%), donde permanecían sueltos (73.8%) o en pozas (21.9%). La alimentación se basó en forrajes, malezas y residuos de cocina. Las principales enfermedades reportadas fueron ectoparásitos (90.1%) y la “peste” (76%). El 71.2% de las familias destinaba los cuyes para autoconsumo y venta, y el 28.2% sólo para autoconsumo. El 96.2% de los encuestados no disponía de servicios de asistencia técnica, créditos, insumos, etc. El 67.5% de los criadores consideraba que mejorarían su crianza con asistencia técnica.A survey was conducted in July 2004 to 160 families rearing Guinea pigs in the district of Santa Cruz, Cajamarca, with the aim of characterizing the production system of these animals. Men were more than 50 years of age (44.6%) and wives were mainly between 31 to 50 years old (42%). Primary school was the main grade of instruction. The main labour activity of the head of the family was agriculture (95.4%) and housekeeping for women (97.2%). Raising guinea pigs was mainly driven by the housewife under a family or traditional system. There were 20.4 guinea pigs on average per family, reared regardless of class, sex and age, preferably in the kitchen (88.8%), free (73.8%) or in pools (21.9%). Feeding was based on forages, weeds and kitchen waste. The main diseases reported were ectoparasites (90.1%) and the «plague» (76%). Guinea pigs were used for consumption and sale (71.2%) or only for home consumption (28.2%). Most of producers (96.2%) indicated that they do not have services such as technical assistance, credit, inputs, etc, and 67.5% considered that they would improve their productivity if technical assistance was available

Spread of the fascioliasis endemic area assessed by seasonal follow-up of rDNA ITS-2 sequenced lymnaeid populations in Cajamarca, Peru

Fascioliasis is a worldwide emerging snail-borne zoonotic trematodiasis with a great spreading capacity linked to animal and human movements, climate change, and anthropogenic modifications of freshwater environments. South America is the continent with more human endemic areas caused by Fasciola hepatica, mainly in high altitude areas of Andean regions. The Peruvian Cajamarca area presents the highest human prevalences reported, only lower than those in the Bolivian Altiplano. Sequencing of the complete rDNA ITS-2 allowed for the specific and haplotype classification of lymnaeid snails collected in seasonal field surveys along a transect including 2007–3473 m altitudes. The species Galba truncatula (one haplotype preferentially in higher altitudes) and Pseudosuccinea columella (one haplotype in an isolated population), and the non-transmitting species Lymnaea schirazensis (two haplotypes mainly in lower altitudes) were found. Climatic seasonality proved to influence G. truncatula populations in temporarily dried habitats, whereas L. schirazensis appeared to be more climatologically independent due to its extreme amphibious ecology. Along the southeastern transect from Cajamarca city, G. truncatula and L. schirazensis shared the same site in 7 localities (46.7% of the water collections studied). The detection of G. truncatula in 11 new foci (73.3%), predominantly in northern localities closer to the city, demonstrate that the Cajamarca transmission risk area is markedly wider than previously considered. Lymnaea schirazensis progressively increases its presence when moving away from the city. Results highlight the usefulness of lymnaeid surveys to assess borders of the endemic area and inner distribution of transmission foci. Similar lymnaeid surveys are still in need to be performed in the wide northern and western zones of the Cajamarca city. The coexistence of more than one lymnaeid transmitting species, together with a morphologically indistinguishable non-transmitting species and livestock movements inside the area, conform a complex scenario which poses difficulties for the needed One Health control intervention.Ministerio de Economía y CompetitividadRevisión por pare

The Role of Thermohaline Mixing in Intermediate- and Low-Metallicity Globular Clusters

It is now widely accepted that globular cluster red giant branch stars owe their strange abundance patterns to a combination of pollution from progenitor stars and in situ extra mixing. In this hybrid theory a first generation of stars imprint abundance patterns into the gas from which a second generation forms. The hybrid theory suggests that extra mixing is operating in both populations and we use the variation of [C/Fe] with luminosity to examine how efficient this mixing is. We investigate the observed red giant branches of M3, M13, M92, M15 and NGC 5466 as a means to test a theory of thermohaline mixing. The second parameter pair M3 and M13 are of intermediate metallicity and our models are able to account for the evolution of carbon along the RGB in both clusters. Although, in order to fit the most carbon-depleted main-sequence stars in M13 we require a model whose initial [C/Fe] abundance leads to a carbon abundance lower than is observed. Furthermore our results suggest that stars in M13 formed with some primary nitrogen (higher C+N+O than stars in M3). In the metal-poor regime only NGC 5466 can be tentatively explained by thermohaline mixing operating in multiple populations. We find thermohaline mixing unable to model the depletion of [C/Fe] with magnitude in M92 and M15. It appears as if extra mixing is occurring before the luminosity function bump in these clusters. To reconcile the data with the models would require first dredge-up to be deeper than found in extant models.Comment: 13 Pages, 3 figures. Accepted for publication in the Astrophysical Journa

El rol de la educación en materia de discriminación derivada de factores étnicos y religiosos

Plantear el rol de la educación en materia de discriminación derivada de factores étnicos y religiosos nos conduce necesariamente a afirmar la igualdad en la diferencia: la Dignidad Humana.Sabemos que todos los seres humanos somos diferentes, sexo, edad, religión, nacionalidad, profesión, nivel educativo etc. sin embargo por encima de cualquier diferencia, todas las personas somos iguales en nuestra naturaleza humana; por el solo hecho de ser personas somos merecedores (dignos) de gozar de características que conforman la dignidad humana. En la actualidad la dignidad humana es la base sobre la que se construye la justicia y el derecho, o sea, que solo por pertenecer a la especie humana nos corresponde gozar de derechos y justicia. Este principio está protegido constitucionalmente en el artículo dieciséis “…todos los habitantes son iguales ante la ley…”.No obstante, sabemos que la convivencia presenta conflictos, las sociedades asisten con frecuencia a conflictos entre sus miembros que van desde las guerras hasta las persecuciones políticas, religiosas o raciales. Muchos de estos conflictos se producen sobre la base de una actitud de discriminación, que se genera cuando se utilizan las diferencias existentes entre las personas para afirmar la superioridad de unas sobre otras. La discriminación origina situaciones de desigualdad. La Universidadcomo ámbito de estudio, reflexión y de formación de profesionales, y más aun nuestra Universidad Católica debe fortalecer a través de los procesos de formación de sus alumnos los principios de promoción y defensa de la dignidad humana. La eliminación de toda forma de discriminación, especialmente la discriminación de género, étnica y racial, y de las diversas formas de intolerancia, así como la promoción y protección de los derechos humanos de los pueblos indígenas y los inmigrantes y el respeto a la diversidad étnica, cultural y religiosa en las Américas, contribuyen al fortalecimiento de la democracia y la participación ciudadana. (Dulitzky Ariel, 2006).Por lo anteriormente analizado es que desde este proyecto de investigación nos vamos a posicionar desde la perspectiva intercultural, ya que consideramos que esta conceptualización es superadora en relación al concepto de muticulturalidad, y contribuyen a combatir la discriminación y la intolerancia religiosa y racial. La perspectiva  intercultural pone énfasis en el terreno de la interacción entre sujetos o entidades culturales diferenciados. El núcleo de la novedad interculturalista se halla en proponer algo sustantivo sobre el deber ser de las relaciones interétnicas, más allá de que no deben ser relaciones no discriminatorias entre iguales y basadas en el respeto y las tolerancia.