Invariant Connections with Torsion on Group Manifolds and Their Application in Kaluza-Klein Theories

Invariant connections with torsion on simple group manifolds $S$ are studied and an explicit formula describing them is presented. This result is used for the dimensional reduction in a theory of multidimensional gravity with curvature squared terms on $M^{4} \times S$. We calculate the potential of scalar fields, emerging from extra components of the metric and torsion, and analyze the role of the torsion for the stability of spontaneous compactification.Comment: 13 pages, LATEX, UB-ECM-PF 93/1

Ecological genetics of freshwater fish: a short review of the genotype–phenotype connection

Genética ecológica de los peces de agua dulce: una breve revisión de la conexión genotipo–fenotipo La ecología molecular o la genética ecológica es una aplicación de la genética de poblaciones que durante las dos últimas décadas ha sufrido un proceso de expansión. Sin embargo, en la ecología molecular predominan los estudios sistemáticos y filogeográficos, con relativamente poco énfasis en el análisis de la base genética del proceso de adaptación a diferentes condiciones ecológicas. Esta relación entre genotipo y fenotipo adaptativo es poco evidente, porque las poblaciones son difíciles de cuantificar y los experimentos son logísticamente complicados. Es interesante destacar que en peces de agua dulce estos estudios no son tan poco frecuentes como en otros grupos de vertebrados. En esta revisión, nuestra intención es resumir los pocos casos en los cuales la relación entre ecología y genética de peces continentales está más desarrollada, principalmente entre marcadores genéticos y fenotipos ecológicos. Palabras clave: Genética ecológica, Ecología molecular, Interacción genotipo–fenotipo, Adaptación, Genética del paisaje, Introducción de especies.Molecular ecology or ecological genetics is an expanding application of population genetics which has flourished in the last two decades but it is dominated by systematic and phylogeographic studies, with relatively little emphasis on the study of the genetic basis of the process of adaptation to different ecological conditions. The relationship between genotype and adaptive phenotypes is weak because populations are often difficult to quantify and experiments are logistically challenging or unfeasible. Interestingly, in freshwater fish, studies to characterize the genetic architecture of adaptive traits are not as rare as in other vertebrate groups. In this review, we summarize the few cases where the relationship between the ecology and genetics of freshwater fish is more developed, namely the relationship between genetic markers and ecological phenotypes. Key words: Ecological genetics, Molecular ecology, Genotype–phenotype relationship, Adaptation, Landscape genetics, Species introduction.Genética ecológica de los peces de agua dulce: una breve revisión de la conexión genotipo–fenotipo La ecología molecular o la genética ecológica es una aplicación de la genética de poblaciones que durante las dos últimas décadas ha sufrido un proceso de expansión. Sin embargo, en la ecología molecular predominan los estudios sistemáticos y filogeográficos, con relativamente poco énfasis en el análisis de la base genética del proceso de adaptación a diferentes condiciones ecológicas. Esta relación entre genotipo y fenotipo adaptativo es poco evidente, porque las poblaciones son difíciles de cuantificar y los experimentos son logísticamente complicados. Es interesante destacar que en peces de agua dulce estos estudios no son tan poco frecuentes como en otros grupos de vertebrados. En esta revisión, nuestra intención es resumir los pocos casos en los cuales la relación entre ecología y genética de peces continentales está más desarrollada, principalmente entre marcadores genéticos y fenotipos ecológicos. Palabras clave: Genética ecológica, Ecología molecular, Interacción genotipo–fenotipo, Adaptación, Genética del paisaje, Introducción de especies

Quality and quantity: transitions in antimicrobial gland use for parasite defense

Parasites are a major force in evolution, and understanding how host life history affects parasite pressure and investment in disease resistance is a general problem in evolutionary biology. The threat of disease may be especially strong in social animals, and ants have evolved the unique metapleural gland (MG), which in many taxa produce antimicrobial compounds that have been argued to have been a key to their ecological success. However, the importance of the MG in the disease resistance of individual ants across ant taxa has not been examined directly. We investigate experimentally the importance of the MG for disease resistance in the fungus-growing ants, a group in which there is interspecific variation in MG size and which has distinct transitions in life history. We find that more derived taxa rely more on the MG for disease resistance than more basal taxa and that there are a series of evolutionary transitions in the quality, quantity, and usage of the MG secretions, which correlate with transitions in life history. These shifts show how even small clades can exhibit substantial transitions in disease resistance investment, demonstrating that host–parasite relationships can be very dynamic and that targeted experimental, as well as large-scale, comparative studies can be valuable for identifying evolutionary transitions

Open educational resources in distributed learning infrastructures: An international comparative study

Open Educational Resources (OER) have the potential to support increased higher education access at a lower cost to rural, remote, lower-socio economic students, alongside lifelong learners and time-poor workers who require upskilling (Bossu & Meier, 2018; Orr, Rimini, & van Damme, 2015). The German Ministry of Education and Research (BMBF) has funded the interdisciplinary project ‘Digital educational architectures: Open learning resources in distributed learning infrastructures – EduArc’ (Learning Lab, 2019), a partnership between the University of Duisburg-Essen, the German Institute for International Educational Research, the Leibnitz Information Centre for Economics and the Carl von Ossietzky University of Oldenburg, in order to explore the development of disseminated learning infrastructures and enable national access to digital education resources. In order to produce infrastructure that is aligned with international developments and trends in higher education digital transformation, nine comparative country studies have been commissioned, alongside Germany, to be undertaken by members of the Centre for Open Education Research (www.uol.de/coer), namely Spain, China, Japan, Korea, Canada, South Africa, Turkey, USA and Australia. The country studies focus on digital transformation across the macro, meso and micro levels, and focus in particular on the infrastructure for disseminating OER in higher education, including repositories and meta-data standards. The studies also focus on national, state and institutional policies; quality assurance mechanisms and key actors; and how change (in terms of funding, managing and promoting infrastructure) is promoted and occurs at all three levels. To date, the macro studies have been completed. In terms of Infrastructure, Spain, China, Japan and Korea have national repositories, including OER, although they are not commonly used in Japanese universities. Canada and USA have decentralised infrastructure, with companies retaining intellectual property rights. All governments have recommendations and funding for digital transformation, however the majority of action is left to individual states and institutions. Spain, Korea and China have national standards for digitalisation, labelling, quality and/or meta-data standards, with the onus on institutions in other countries. The next stage of this research, the meso level, is currently underway

Potential of embryos transfer as a tool for the conservation of the spanish-arab horse breed

The Spanish-Arab horse breed is registred in the Spanish catalogue of breeds as an endangered breed into the special protection category. A strategy of conservation basedon the embryos transferring is presented here with the intention of the use so this tool to utilize male and female genetic potentiality. For this assay a total purebreed animals of 8 females and 1 male were selected, all of then submitted by the Spanish Union of Pure Breed Spanish-Arab Breeders. The percentage of embrionary collection was of 100% of the donor females. The rate of gestations at 25 days alter transference was 66.7% and at 50 days was 33.7%.La raza equina Hispano-Árabe esta registrada en el catálogo oficial de razas de España como raza en peligro de extinción en la categoría de protección especial. Se plantea como estrategia de conservación el uso de la técnica de transferencia embrionaria, como herramienta en el aprovechamiento genético no sólo del macho sino también de las hembras. Para dicho ensayo Se seleccionaron un total de 8 yeguas y 1 macho de raza Hispano-Árabe cedidas por la Unión Española de Ganaderos de Pura Raza Hispano-Árabe. Entre las yeguas donantes que fueron mantenidas en este programa de transferencia embrionaria se obtuvo un porcentaje de recogida de embriones del 100%. De este modo, la tasa de gestación a los 25 días fue 66,7%, mientras que a los 50 días sólo alcanzó el 33,7%

Mujeres y artesanías en San José de Ocú : reserva del patrimonio nacional

El propósito de esta investigación es comprender el origen, desarrollo y características del trabajo de las mujeres artesanas de la comunidad de San José de Ocú. Para lograrlo, primero se describen las condiciones geográficas e históricas de San José de Ocú. Luego, se examina el papel de la mujer artesana como transmisora de la herencia cultural de la comunidad relacionada con la confección del Montuno Ocueño: el pantalón “calzón” o “chingo”, la camisa o cotona y la descripción de las marcas de la camisa o cotona ocueña. El uso de la metodología de la Historia Oral me permitió indagar detalles específicos de este trabajo artesanal al revelar las artesanas entrevistadas los tipos de instrumentos, materiales y técnicas y empleados para la confección de la indumentaria femenina, la camisa masculina y el sombrero. Al final, valoro la confección de los “Vestido Neo artesanal” como un producto derivado de las técnicas artesanales tradicionales, que responden a la demanda del mercado y los gustos actuales de las mujeres panameñas, que representa para estas artesanas un ingreso adicional. Finalmente, se presentan las conclusiones alcanzadas en esta investigación y se formulan algunas recomendaciones

HISTORICAL SEISMICITY OF THE CALDAS DEPARTMENT (COLOMBIA)

A study of historical seismicity in the Province of Caldas was made by means of a systematic search of documentalsources such as files, manuscripts, printed documents, newspapers and magazines, aiming to widen the temporary timelapse and the precision of earthquakes that have left remains and have caused considerable damages in the population.This problem was approached by the use of intensive and extensive searching methods. The intensity was assigned usingthe European Macroseismic Scale (EMS-98). Finally, a site catalogue is proposed for the events that have caused a greatereffect in the state of Caldas, as well as damage degree and intensity maps for the major earthquakes as those of February4, 1938; July 30, 1962; and November 23, 1979. Key words: Historical seismicity, macroseismic, damage degree, intensity, catalogue.Se realizó un estudio de la sismicidad histórica del Departamento de Caldas, mediante una búsqueda sistemática defuentes documentales como archivos, documentos impresos, periódicos y revistas con el fin de ampliar la ventanatemporal y la precisión de terremotos que han dejado efectos y causado daños considerables en su población. Aproximamoseste problema utilizando métodos intensivistas y extensivistas en la búsqueda de la información. La intensidad se asignóutilizando la Escala Macrosísmica Europea (EMS-98). Finalmente se propone un catalogo de sitio para los eventos quehan causado mayor efecto en el Departamento de Caldas, y mapas de grados de daños e intensidades para los eventos demayor trascendencia como los ocurridos el 4 de Febrero de 1938, el 30 de Julio de 1962 y el 23 de Noviembre de 1979. Palabras claves: Sismicidad histórica, macrosísmica, grado de daños, intensidad, catálogo.   &nbsp

Photometric type Ia supernova surveys in narrow band filters

We study the characteristics of a narrow band type Ia supernova survey through simulations based on the upcoming Javalambre Physics of the accelerating universe Astrophysical Survey (J-PAS). This unique survey has the capabilities of obtaining distances, redshifts, and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the supernova typing performance, the ability to recover light curve parameters given by the SALT2 model, the photometric redshift precision from type Ia supernova light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large type Ia supernova samples (up to 250 supernovae at $z<0.5$ per month of search) with low core collapse contamination ($\sim 1.5$ per cent), good precision on the SALT2 parameters (average $\sigma_{m_B}=0.063$, $\sigma_{x_1}=0.47$ and $\sigma_c=0.040$) and on the distance modulus (average $\sigma_{\mu}=0.16$, assuming an intrinsic scatter $\sigma_{\mathrm{int}}=0.14$), with identified systematic uncertainties $\sigma_{\mathrm{sys}}\lesssim 0.10 \sigma_{\mathrm{stat}}$. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of $\sigma_z=0.005$, apart from $\sim$ 2 per cent of outliers. We also present a few strategies for optimising the survey's outcome. Together with the detailed host galaxy information, narrow band surveys can be very valuable for the study of supernova rates, spectral feature relations, intrinsic colour variations and correlations between supernova and host galaxy properties, all of which are important information for supernova cosmological applications.Comment: 20 pages, 12 tables and 26 figures. Version accepted by MNRAS, with results slightly different from previous on

The free surface of superfluid 4He at zero temperature

The structure and energetics of the free surface of superfluid $^4$He are studied using the diffusion Monte Carlo method. Extending a previous calculation by Vall\'es and Schmidt, which used the Green's function Monte Carlo method, we study the surface of liquid $^4$He within a slab geometry using a larger number of particles in the slab and an updated interatomic potential. The surface tension is accurately estimated from the energy of slabs of increasing surface density and its value is close to one of the two existing experimental values. Results for the density profiles allow for the calculation of the surface width which shows an overall agreement with recent experimental data. The dependence on the transverse direction to the surface of other properties such as the two-body radial distribution function, structure factor, and one-body density matrix is also studied. The condensate fraction, extracted from the asymptotic behavior of the one-body density matrix, shows an unambiguous enhancement when approaching the surface.Comment: RevTex, 11 pages, accepted in Phys. Rev.

Neuregulin 3 Mediates Cortical Plate Invasion and Laminar Allocation of GABAergic Interneurons

Neural circuits in the cerebral cortex consist of excitatory pyramidal cells and inhibitory interneurons. These two main classes of cortical neurons follow largely different genetic programs, yet they assemble into highly specialized circuits during development following a very precise choreography. Previous studies have shown that signals produced by pyramidal cells influence the migration of cortical interneurons, but the molecular nature of these factors has remained elusive. Here, we identified Neuregulin 3 (Nrg3) as a chemoattractive factor expressed by developing pyramidal cells that guides the allocation of cortical interneurons in the developing cortical plate. Gain- and loss-of-function approaches reveal that Nrg3 modulates the migration of interneurons into the cortical plate in a process that is dependent on the tyrosine kinase receptor ErbB4. Perturbation of Nrg3 signaling in conditional mutants leads to abnormal lamination of cortical interneurons. Nrg3 is therefore a critical mediator in the assembly of cortical inhibitory circuits