2,659 research outputs found

    Dynamics of Sus scrofa semen quality in the western-central region of Colombia

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    Con el fin de caracterizar la dinámica de la calidad seminal en Sus scrofa (orden Artiodactyla, familia Suidae) en el centro-occidente colombiano, durante siete años se recopiló en el Laboratorio de Biología de la Reproducción de la Universidad de Caldas (Colombia), información de 1017 evaluaciones de 177 machos procedentes de 12 planteles porcinos ubicados entre los 700 y 2600 msnm en diferentes sistemas intertropicales. La base de datos incluyó las variables seminales: concentración, morfología (cabeza, pieza intermedia y cola), integridad estructural de la membrana (IEM), integridad acrosómica (IAC), integridad funcional de la membrana (IFM), gotas citoplasmáticas (GC): gotas citoplasmáticas proximales (GCP), gotas citoplasmáticas distales (GCD) y gotas citoplasmáticas totales (GCT), así como información del grupo racial de los machos (grac): cruzado materno (cm), cruzado paterno (cp), puro paterno (pp) y puro materno (pm), y grupo etario (gredad): joven (hasta 18 meses), maduro (19 a 36 meses) y viejo (mayor a 37 meses). Los datos se exploraron mediante la estimación de estadísticos descriptivos, se analizaron usando un modelo log-lineal, consistente en una regresión Poisson con una función de enlace logarítmica mediante el PROC GENMOD de SAS (SAS Inst. Cary, NC). Se evaluó el efecto de grupo etario y grupo racial sobre las variables de calidad seminal usando un modelo mixto para mediciones repetidas en el mismo verraco a través del tiempo. Se calcularon los coeficientes de correlación de Spearman entre las variables seminales. Las variables: cabeza macro, micro y piriforme, tracto intermedio doble, excéntrico y engrosado, cola en látigo, lazo, escalera, ovillo y reflejo distal, presentaron prevalencias inferiores al 1%. La mitad de las dosis de semen diluido recibidas mostraron concentraciones superiores a 35 millones de células ml-1. Los valores más altos de IEM se encontraron en los reproductores cm y pp. Al relacionar la variable IFM con grupo racial, los reproductores cp, pm y cm no presentan diferencias entre sí. La IAC en los cm presentaron un porcentaje mayor que los cp, y estos mayor que los pm. Se aprecia una mayor presentación de GCT a medida que avanza la edad, con un mayor porcentaje de GCP en animales viejos que jóvenes, los animales maduros presentaron valores intermedios entre ellos. Las GCT excedieron el 15% de presentación, siendo siempre mayor la presentación de GCD que GCP. El total de gotas está negativamente correlacionado con la IEM y la IAC, pero positivamente con la IFM, la misma tendencia se observa en la correlaciones de las gotas citoplasmáticas distales; sin embargo, la correlación de las gotas proximales con la integridad estructural pierde fuerza y con la integridad funcional pierde la significancia, aunque están negativamente correlacionadas con la integridad del acrosoma. Los valores para MSI, MFI and ACRI, no limitan la calidad de las muestras de semen en esta población.In order to characterize the dynamics of Sus scrofa (order Artiodactyla, family Suidae) semen quality in the Western-central region of Colombia, information of 1,017 assessments from 177 males from 12 swine farms located between 700 and 2,600 meters above sea level in different inter-tropical systems was collected in the Laboratory of Reproductive Biology at Universidad de Caldas (Colombia) during seven years. The database included the seminal variables: concentration, morphology (head, midpiece and tail), membrane structural integrity (MSI), acrosome integrity (ACRI), and membrane functional integrity (MFI) proximal citoplasmic droplets (PCD), distal citoplasmic droplets (DCD), and total citoplasmic droplets (TCD). Additionally, the racial group of the male (grac): maternal cross (cm), paternal cross (cp), paternal pure (pp), maternal pure (pm) and age group (agegr): young (up to 18 months), mature (19 to 36 months) and old (over 37 months) were registered. Data was explored by estimating descriptive statistics; it was analyzed using a log-linear model consisting of a Poisson regression with a log link function using the PROC GENMOD of SAS (SAS Inst. Cary, NC). The effect of age group and racial group on semen quality variables using a mixed model for repeated measurements in the same boar over time were evaluated. The Spearman correlation coefficients between variables were calculated. The variables: macro, micro and pyriform head; double, eccentric, and thickened midpiece; tail whip; ladder bow; ball and distal reflex showed less than 1% prevalence. The highest values of FMI were found in cm and pp. Males cp, cm and pm do not differ from each other in MFI, but all had higher values than pp. The ACRI in cm was higher than cp, and these higher than pm. Presentation of TCD increased with age, with a higher percentage of PCD in older animals than in younger animals; mature animals showed intermediate values between them. The TCD exceeded 15% of presentation, being always higher for PCD than for GCP. The TCD is negatively correlated with MSI and ARCI, but positively correlated with MFI. The same trend is observed in the correlations with distal cytoplasmic droplets. However, the correlation of proximal droplets with the structural integrity loses significance, though they are negatively correlated with acrosome integrity. Values for MSI, MFI and ACRI, do not limit the quality of the samples in this population

    Supporting info item, In: "Using SHRIMP zircon dating to unravel tectonothermal events in arc environments. The early Palaeozoic arc of NW Iberia revisited"

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    Dating of zircon cores and rims from granulites developed in a shear zone provides insights into the complex relationship between magmatism and metamorphism in the deep roots of arc environments. The granulites belong to the uppermost allochthonous terrane of the NW Iberian Massif, which forms part of a Cambro-Ordovician magmatic arc developed in the peri-Gondwanan realm. The obtained zircon ages confirm that voluminous calc-alkaline magmatism peaked around 500 Ma and was shortly followed by granulite facies metamorphism accompanied by deformation at c. 480 Ma, giving a time framework for crustal heating, regional metamorphism, deformation and partial melting, the main processes that control the tectonothermal evolution of arc systems. Traces of this arc can be discontinuously followed in different massifs throughout the European Variscan Belt, and we propose that the uppermost allochthonous units of the NW Iberian Massif, together with the related terranes in Europe, constitute an independent and coherent terrane that drifted away from northern Gondwana prior to the Variscan collisional orogenesis

    Using synchronization to improve earthquake forecasting in a cellular automaton model

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    A new forecasting strategy for stochastic systems is introduced. It is inspired by the concept of anticipated synchronization between pairs of chaotic oscillators, recently developed in the area of Dynamical Systems, and by the earthquake forecasting algorithms in which different pattern recognition functions are used for identifying seismic premonitory phenomena. In the new strategy, copies (clones) of the original system (the master) are defined, and they are driven using rules that tend to synchronize them with the master dynamics. The observation of definite patterns in the state of the clones is the signal for connecting an alarm in the original system that efficiently marks the impending occurrence of a catastrophic event. The power of this method is quantitatively illustrated by forecasting the occurrence of characteristic earthquakes in the so-called Minimalist Model.Comment: 4 pages, 3 figure

    Finite time singularities for the free boundary incompressible Euler equations

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    In this paper, we prove the existence of smooth initial data for the 2D free boundary incompressible Euler equations (also known for some particular scenarios as the water wave problem), for which the smoothness of the interface breaks down in finite time into a splash singularity or a splat singularity.Ministerio de Ciencia e InnovaciónEuropean Research CouncilNational Science Foundatio

    Structural stability for the splash singularities of the water waves problem

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    In this paper we show a structural stability result for water waves. The main motivation for this result is that we would like to exhibit a water wave whose interface starts as a graph and ends in a splash. Numerical simulations lead to an approximate solution with the desired behaviour. The stability result will conclude that near the approximate solution to water waves there is an exact solution.Ministerio de Ciencia e InnovaciónInstituto de Ciencias Matemáticas Severo OchoaEuropean Research CouncilNational Science Foundatio

    Splash singularity for water waves

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    We exhibit smooth initial data for the two-dimensional (2D) waterwave equation for which we prove that smoothness of the interface breaks down in finite time. Moreover, we show a stability result together with numerical evidence that there exist solutions of the 2D water-wave equation that start from a graph, turn over, and collapse in a splash singularity (self-intersecting curve in one point) in finite time.Ministerio de Ciencia e InnovaciónEuropean Research CouncilNational Science Foundatio

    Increased neurotransmitter release at the neuromuscular junction in a mouse model of polyglutamine disease

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    In Huntington's disease (HD), the expansion of polyglutamine (polyQ) repeats at the N terminus of the ubiquitous protein huntingtin (htt) leads to neurodegeneration in specific brain areas. Neurons degenerating in HD develop synaptic dysfunctions. However, it is unknown whether mutant htt impacts synaptic function in general. To investigate that, we have focused on the nerve terminals of motor neurons that typically do not degenerate in HD. Here, we have studied synaptic transmission at the neuromuscular junction of transgenic mice expressing a mutant form of htt (R6/1 mice).Wehave found that the size and frequency of miniature endplate potentials are similar in R6/1 and control mice. In contrast, the amplitude of evoked endplate potentials in R6/1 mice is increased compared to controls. Consistent with a presynaptic increase of release probability, synaptic depression under high-frequency stimulation is higher in R6/1 mice. In addition, no changes were detected in the size and dynamics of the recycling synaptic vesicle pool. Moreover, we have found increased amounts of the synaptic vesicle proteins synaptobrevin 1,2/VAMP 1,2 and cysteine string protein-α, and the SNARE protein SNAP-25, concomitant with normal levels of other synaptic vesicle markers. Our results reveal that the transgenic expression of a mutant form of htt leads to an unexpected gain of synaptic function. That phenotype is likely not secondary to neurodegeneration and might be due to a primary deregulation in synaptic protein levels. Our findings could be relevant to understand synaptic toxic effects of proteins with abnormal polyQ repeats. Copyright©2011 the authors.Instituto de Salud Carlos III (Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas), the Spanish Ministry of Science and Innovation (BFU2007-66008 to R.F-C., SAF2009-08233 to J.J.L., and Juan de la Cierva contracts to J.L.R. and C.T.-Z.), Junta de Andalucía (P07-CVI- 02854, P06-CVI-02392), Comunidad Autónoma de Madrid, Fundación Ramón Areces, and Fondo Europeo de Desarrollo RegionalPeer Reviewe

    The Conformational Stability and Biophysical Properties of the Eukaryotic Thioredoxins of Pisum Sativum Are Not Family-Conserved

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    Thioredoxins (TRXs) are ubiquitous proteins involved in redox processes. About forty genes encode TRX or TRX-related proteins in plants, grouped in different families according to their subcellular localization. For instance, the h-type TRXs are located in cytoplasm or mitochondria, whereas f-type TRXs have a plastidial origin, although both types of proteins have an eukaryotic origin as opposed to other TRXs. Herein, we study the conformational and the biophysical features of TRXh1, TRXh2 and TRXf from Pisum sativum. The modelled structures of the three proteins show the well-known TRX fold. While sharing similar pH-denaturations features, the chemical and thermal stabilities are different, being PsTRXh1 (Pisum sativum thioredoxin h1) the most stable isoform; moreover, the three proteins follow a three-state denaturation model, during the chemical-denaturations. These differences in the thermal- and chemical-denaturations result from changes, in a broad sense, of the several ASAs (accessible surface areas) of the proteins. Thus, although a strong relationship can be found between the primary amino acid sequence and the structure among TRXs, that between the residue sequence and the conformational stability and biophysical properties is not. We discuss how these differences in the biophysical properties of TRXs determine their unique functions in pea, and we show how residues involved in the biophysical features described (pH-titrations, dimerizations and chemical-denaturations) belong to regions involved in interaction with other proteins. Our results suggest that the sequence demands of protein-protein function are relatively rigid, with different protein-binding pockets (some in common) for each of the three proteins, but the demands of structure and conformational stability per se (as long as there is a maintained core), are less so

    Graphene for energy storage

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    Due to its excellent mechanical, termal, optical and electrical properties, graphene has recently attracted increasing attention. It provides a huge surface area (2630m2 g-1) and high electrical conductivity, making it an attractive material for applications in energy-storage systems

    Finite time singularities for water waves with surface tension

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    Here we consider the 2D free boundary incompressible Euler equation with surface tension. We prove that the surface tension does not prevent a finite time splash or splat singularity, i.e. that the curve touches itself either in a point or along an arc. To do so, the main ingredients of the proof are a transformation to desingularize the curve and a priori energy estimates.Ministerio de Ciencia e InnovaciónEuropean Research CouncilNational Science Foundatio
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