304 research outputs found

    Classical emulation of quantum-coherent thermal machines

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    The performance enhancements observed in various models of continuous quantum thermal machines have been linked to the buildup of coherences in a preferred basis. But, is this connection always an evidence of `quantum-thermodynamic supremacy'? By force of example, we show that this is not the case. In particular, we compare a power-driven three-level continuous quantum refrigerator with a four-level combined cycle, partly driven by power and partly by heat. We focus on the weak driving regime and find the four-level model to be superior since it can operate in parameter regimes in which the three-level model cannot, it may exhibit a larger cooling rate, and, simultaneously, a better coefficient of performance. Furthermore, we find that the improvement in the cooling rate matches the increase in the stationary quantum coherences exactly. Crucially, though, we also show that the thermodynamic variables for both models follow from a classical representation based on graph theory. This implies that we can build incoherent stochastic-thermodynamic models with the same steady-state operation or, equivalently, that both coherent refrigerators can be emulated classically. More generally, we prove this for any N-level weakly driven device with a `cyclic' pattern of transitions. Therefore, even if coherence is present in a specific quantum thermal machine, it is often not essential to replicate the underlying energy conversion process.Comment: 13 pages, 4 figures; references updated; appendix adde

    Identification and functional analysis of novel phosphorylation sites in the RNA surveillance protein Upf1.

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    One third of inherited genetic diseases are caused by mRNAs harboring premature termination codons as a result of nonsense mutations. These aberrant mRNAs are degraded by the Nonsense-Mediated mRNA Decay (NMD) pathway. A central component of the NMD pathway is Upf1, an RNA-dependent ATPase and helicase. Upf1 is a known phosphorylated protein, but only portions of this large protein have been examined for phosphorylation sites and the functional relevance of its phosphorylation has not been elucidated in Saccharomyces cerevisiae. Using tandem mass spectrometry analyses, we report the identification of 11 putative phosphorylated sites in S. cerevisiae Upf1. Five of these phosphorylated residues are located within the ATPase and helicase domains and are conserved in higher eukaryotes, suggesting a biological significance for their phosphorylation. Indeed, functional analysis demonstrated that a small carboxy-terminal motif harboring at least three phosphorylated amino acids is important for three Upf1 functions: ATPase activity, NMD activity and the ability to promote translation termination efficiency. We provide evidence that two tyrosines within this phospho-motif (Y-738 and Y-742) act redundantly to promote ATP hydrolysis, NMD efficiency and translation termination fidelity

    Testing the validity of the ‘local’ and ‘global’ GKLS master equations on an exactly solvable model

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    When deriving a master equation for a multipartite weakly-interacting open quantum systems, dissipation is often addressed locally on each component, i.e. ignoring the coherent couplings, which are later added ‘by hand’. Although simple, the resulting local master equation (LME) is known to be thermodynamically inconsistent. Otherwise, one may always obtain a consistent global master equation (GME) by working on the energy basis of the full interacting Hamiltonian. Here, we consider a two-node ‘quantum wire’connected to two heat baths. The stationary solution of the LME and GME are obtained and benchmarked against the exact result. Importantly, in our model, the validity of the GME is constrained by the underlying secular approximation. Whenever this breaks down (for resonant weakly-coupled nodes), we observe that the LME, in spite of being thermodynamically flawed: (a) predicts the correct steady state, (b) yields with the exact asymptotic heat currents, and (c) reliably reflects the correlations between the nodes. In contrast, the GME fails at all three tasks. Nonetheless, as the inter-node coupling grows, the LME breaks down whilst the GME becomes correct. Hence, the global and local approach may be viewed as complementary tools, best suited to different parameter regimes

    Effect of 8-Week Consumption of a Dietary Pattern Based on Fruit, Avocado, Whole Grains, and Trout on Postprandial Inflammatory and Oxidative Stress Gene Expression in Obese People

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    Overweight and obesity constitute a major global public health problem. Healthy dietary patterns induce changes at the molecular level. Currently, there are no studies evaluating the effect of a diet based on fruit, avocado, whole grains, and trout (FAWGT diet) on the expression of obesity-related genes. This randomized controlled crossover study included 44 obese Colombians with BMI ≥30 kg/m2 who followed either a FAWGT diet or a usual diet (UD) characterized by a high intake of saturated fat and foods rich in processed carbohydrates. After 8 weeks of intervention, a postprandial expression study of inflammation and oxidative stress-related genes was carried out with a real-time PCR. The intervention with a FAWGT diet decreased the expression of inflammatory (NFKB1, IL6, IL1β) and oxidative stress (NFE2L2) genes compared with the intake of the UD. Finally, the postprandial expression of NFkB1 was positively correlated with triglyceride levels after a dietary intervention with the FAWGT diet and the IL1β gene, and likewise with insulin levels after following the usual diet. The consumption of the FAWGT diet for 8 weeks reduced the inflammatory status; thus, it can be considered a valid alternative to other healthy diets, since it induces beneficial changes on the genes involved in inflammation and oxidative stress in obese people

    Isogenic GAA-KO Murine Muscle Cell Lines Mimicking Severe Pompe Mutations as Preclinical Models for the Screening of Potential Gene Therapy Strategies

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    Pompe disease (PD) is a rare disorder caused by mutations in the acid alpha-glucosidase (GAA) gene. Most gene therapies (GT) partially rely on the cross-correction of unmodified cells through the uptake of the GAA enzyme secreted by corrected cells. In the present study, we generated isogenic murine GAA-KO cell lines resembling severe mutations from Pompe patients. All of the generated GAA-KO cells lacked GAA activity and presented an increased autophagy and increased glycogen content by means of myotube differentiation as well as the downregulation of mannose 6-phosphate receptors (CI-MPRs), validating them as models for PD. Additionally, different chimeric murine GAA proteins (IFG, IFLG and 2G) were designed with the aim to improve their therapeutic activity. Phenotypic rescue analyses using lentiviral vectors point to IFG chimera as the best candidate in restoring GAA activity, normalising the autophagic marker p62 and surface levels of CI-MPRs. Interestingly, in vivo administration of liver-directed AAVs expressing the chimeras further confirmed the good behaviour of IFG, achieving cross-correction in heart tissue. In summary, we generated different isogenic murine muscle cell lines mimicking the severe PD phenotype, as well as validating their applicability as preclinical models in order to reduce animal experimentation.Fundacion Poco Frecuente (Almeria)Asociacion Espanola de Enfermos de Glucogenosis (AEEG)Asociacion Espanola de Enfermos de Pompe (AEEP

    Transcriptome profiling of grapevine seedless segregants during berry development reveals candidate genes associated with berry weight

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    Indexación: Web of Science; PubMedBackground Berry size is considered as one of the main selection criteria in table grape breeding programs. However, this is a quantitative and polygenic trait, and its genetic determination is still poorly understood. Considering its economic importance, it is relevant to determine its genetic architecture and elucidate the mechanisms involved in its expression. To approach this issue, an RNA-Seq experiment based on Illumina platform was performed (14 libraries), including seedless segregants with contrasting phenotypes for berry weight at fruit setting (FST) and 6–8 mm berries (B68) phenological stages. Results A group of 526 differentially expressed (DE) genes were identified, by comparing seedless segregants with contrasting phenotypes for berry weight: 101 genes from the FST stage and 463 from the B68 stage. Also, we integrated differential expression, principal components analysis (PCA), correlations and network co-expression analyses to characterize the transcriptome profiling observed in segregants with contrasting phenotypes for berry weight. After this, 68 DE genes were selected as candidate genes, and seven candidate genes were validated by real time-PCR, confirming their expression profiles. Conclusions We have carried out the first transcriptome analysis focused on table grape seedless segregants with contrasting phenotypes for berry weight. Our findings contributed to the understanding of the mechanisms involved in berry weight determination. Also, this comparative transcriptome profiling revealed candidate genes for berry weight which could be evaluated as selection tools in table grape breeding programs.http://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-016-0789-

    De la libreta de prácticas a la comunicación científica

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    Entre las competencias transversales que debe adquirir el alumnado en el Grado de Ciencias del Mar, se encuentra el desarrollo de la capacidad de análisis y razonamiento crítico y la realización, presentación y defensa de textos e informes científicos, tanto de forma escrita como oral. Dichas competencias son específicamente tratadas en la asignatura del primer curso “Iniciación a las Ciencias del Mar”. Para la fijación de estas competencias, en estudios previos se ha demostrado la importancia de coordinar la parte práctica de asignaturas complementarias y/o afines para que los alumnos puedan aplicar de forma transversal los conocimientos adquiridos y no perciban las asignaturas y sus actividades asociadas como islas de conocimiento sin interconexión. En este artículo se hace un análisis de la coordinación trasversal de las competencias adquiridas por el alumnado del Grado de Ciencias del Mar en la asignatura Iniciación a las Ciencias del Mar con asignaturas de cursos posteriores, para la realización de las libretas de prácticas siguiendo una metodología científica

    Violencia política y conflictos sociales en América Latina

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    La violencia socio-económica como categoría de estudio en las ciencias sociales y humanas, ha venido adquiriendo creciente relevancia en América Latina. Los problemas y variables metodológicas asociadas a su investigación han sido abordados con mayor profundidad desde la sociología, el Derecho, la Ciencia política y la Psicología Social. Es por esto, que esta publicación se propone abordar la violencia socio-económica como una categoría de análisis e investigación interdisciplinaria, posibilitando la reflexión académica en torno a las dinámicas de construcción del poder, la institucionalidad y los movimientos sociales en América Latina.Introducción; Parte I. Violencia, derechos humanos y criminalidad. Conflicto y violencias en Colombia / Roberto González Arana, Ivonne Molinares Guerrero; Derechos humanos y seguridad democrática en Colombia: ¿un equilibrio posible? / César Barreira; Conflictividad, violencia y control social: saberes latinoamericanos contemporáneos / José Vicente Tavares-dos-Santos; Pensar la justicia de adolescentes desde el campo jurídico / Nilia Viscardi, Marcia Barbero; Parte ii. Conflictos: armados, étnicos, territoriales y por los recursos naturales. Aproximaciones teórico-conceptuales en torno al conflicto armado colombiano / Luis Fernando Trejos Rosero; El conflicto mapuche y el estado de Chile: una reflexión sobre la violencia y la imagen de Chile en el bicentenario / Loreto Correa V.; Entre la violencia política y social. Una revisión a la inmigración africana subsahariana occidental en Buenos Aires (1990-2010) / Mary Luz Estupiñán Serrano; Producción de nuevas espacialidades y cambios de autoridad. Interacción globalización-conflicto armado-grupos étnicos / Clara Inés Aramburo Siegert; Los recursos mineros y la protesta ciudadana en la Argentina de la última década / Orietta Favaro, Graciela Iuorno; Performances do crime: componentes dramáticos e teatrais dos grandes roubos no Brasil / Jania Perla Diógenes de Aquino

    Factores de riesgo para trastornos de la alimentación en los alumnos de la Universidad de Manizales

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    ResumenObjetivo: Determinar la frecuencia de los factores de riesgo para trastornos de la alimentación en estudiantes de la Universidad de Manizales. Materiales y métodos: De 3,610 estudiantes regulares de la Universidad  de Manizales se tomó una muestra de 165 estudiantes, quienes respondieron un cuestionario integrado compuesto por variables demográficas, las escalas de Zung para ansiedad o depresión,el Eating Disorderrs Inventory (EDI2) y el Apgar familiar; además se tomaron las medidas de peso, talla, índice de masa corporal y pliegue en el antebrazo. Resultado: Un12.7% de la población presentó factor de riesgo positivo para trastornos de la conducta alimentaría, 17.3% de la población femenina y el 3.8% de la población masculina; las personas con mayor factor de riesgo fueron las mujeres en la facultad de Comunicación Social y Periodismo (24.1%). Se determinó una  relación significativa entre la variable impulso por la delgadez con la ansiedad o depresión. El mayor índice de masa corporal y de porcentaje de grasa está asociado con un aumentoen la variable impulso por la delgadez. Conclusiones:Se encontraron factores de riesgo asociados con trastornos de la alimentación. La frecuencia del factor de riesgo según EDI2 en este estudio fue más baja que la encontrada en estudios realizados en Medellín y Bogotá.[Cano AA, Castaño JJ, Corredor DA, García AM, González M, Lloreda OL, et al. Factores de riesgo para trastornos de la alimentación en los alumnos de la Universidad de Manizales. MedUNAB 2007; 10:187-194].Palabras claves: Trastornos de la conducta alimentaria, factores de riesgo; Anorexia nerviosa, Bulimia
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