148 research outputs found

    A coinductive semantics of the Unlimited Register Machine

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    We exploit (co)inductive specifications and proofs to approach the evaluation of low-level programs for the Unlimited Register Machine (URM) within the Coq system, a proof assistant based on the Calculus of (Co)Inductive Constructions type theory. Our formalization allows us to certify the implementation of partial functions, thus it can be regarded as a first step towards the development of a workbench for the formal analysis and verification of both converging and diverging computations

    Computed tomography porosity and spherical indentation for determining cortical bone millimetre-scale mechanical properties

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    The cortex of the femoral neck is a key structural element of the human body, yet there is not a reliable metric for predicting the mechanical properties of the bone in this critical region. This study explored the use of a range of non-destructive metrics to measure femoral neck cortical bone stiffness at the millimetre length scale. A range of testing methods and imaging techniques were assessed for their ability to measure or predict the mechanical properties of cortical bone samples obtained from the femoral neck of hip replacement patients. Techniques that can potentially be applied in vivo to measure bone stiffness, including computed tomography (CT), bulk wave ultrasound (BWUS) and indentation, were compared against in vitro techniques, including compression testing, density measurements and resonant ultrasound spectroscopy. Porosity, as measured by micro-CT, correlated with femoral neck cortical bone’s elastic modulus and ultimate compressive strength at the millimetre length scale. Large-tip spherical indentation also correlated with bone mechanical properties at this length scale but to a lesser extent. As the elastic mechanical properties of cortical bone correlated with porosity, we would recommend further development of technologies that can safely measure cortical porosity in vivo. Introductio

    Mesure des courbes de dispersion des ondes guidées circonférentielles dans une coque elliptique par retournement temporel

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    Le retournement temporel permet de déterminer la position de sources acoustiques à partir du signal reçu sur un réseau de récepteurs. On s'intéresse au cas d'une source directive mobile, modélisant une onde guidée circonférentielle dans une coque, rayonnant dans le milieu extérieur. L'analyse de la forme des fronts d'onde aux récepteurs détermine la position de la source effective qui dépend de la vitesse de phase. Cette analyse a permis d'étendre au cas de sections elliptiques une méthode de mesure des courbes de dispersion déjà existante pour des sections circulaires

    Recombinant pediocin in Lactococcus lactis:increased production by propeptide fusion and improved potency by co-production with PedC

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    We describe the impact of two propeptides and PedC on the production yield and the potency of recombinant pediocins produced in Lactococcus lactis. On the one hand, the sequences encoding the propeptides SD or LEISSTCDA were inserted between the sequence encoding the signal peptide of Usp45 and the structural gene of the mature pediocin PA-1. On the other hand, the putative thiol-disulfide oxidoreductase PedC was coexpressed with pediocin. The concentration of recombinant pediocins produced in supernatants was determined by enzyme-linked immunosorbent assay. The potency of recombinant pediocins was investigated by measuring the minimal inhibitory concentration by agar well diffusion assay. The results show that propeptides SD or LEISSTCDA lead to an improved secretion of recombinant pediocins with apparently no effect on the antibacterial potency and that PedC increases the potency of recombinant pediocin. To our knowledge, this study reveals for the first time that pediocin tolerates fusions at the N-terminal end. Furthermore, it reveals that only expressing the pediocin structural gene in a heterologous host is not sufficient to get an optimal potency and requires the accessory protein PedC. In addition, it can be speculated that PedC catalyses the correct formation of disulfide bonds in pediocin.</p

    A formally verified compiler back-end

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    This article describes the development and formal verification (proof of semantic preservation) of a compiler back-end from Cminor (a simple imperative intermediate language) to PowerPC assembly code, using the Coq proof assistant both for programming the compiler and for proving its correctness. Such a verified compiler is useful in the context of formal methods applied to the certification of critical software: the verification of the compiler guarantees that the safety properties proved on the source code hold for the executable compiled code as well

    Mejoras operativas en la valoración genética del ganado caprino lechero de raza murciano-granadina

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    Se compararon diferentes modelos para la evaluación de cabras lecheras para su uso en un programa de mejora genética establecido entre la Asociación de Ganaderos de Caprino de Raza Murciano-Granadina de la Comunidad Valenciana y el Centro de Investigación y Tecnología Animal del Instituto Valenciano de Investigaciones Agrarias. Se compararon en primer lugar dos modelos mixtos con diferente estructura de covarianzas. También se realizaron comparaciones entre modelos que incluyeron otros efectos sistemáticos: edad de la hembra en el momento del parto y días desde el parto hasta el primer control de la lactación. Se consideraron los caracteres estandarizados producción de leche y porcentajes de grasa y proteína. Las comparaciones se realizaron considerando criterios estadísticos de información. Los resultados indican que el modelo de repetibilidad es el más adecuado al tener en cuenta las covarianzas entre medidas de una cabra. La inclusión del efecto edad de la hembra al parto sólo fue ventajosa para el carácter producción de leche. La consideración del efecto tiempo desde el parto al primer control lechero fue positiva para los caracteres de producción de leche y de porcentaje de proteína. Ninguno de los efectos incluidos mejoró el modelo actualmente utilizado para porcentaje de grasa

    Regulation of the Na,K-ATPase Gamma-Subunit FXYD2 by Runx1 and Ret Signaling in Normal and Injured Non-Peptidergic Nociceptive Sensory Neurons

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    Dorsal root ganglia (DRGs) contain the cell bodies of sensory neurons which relay nociceptive, thermoceptive, mechanoceptive and proprioceptive information from peripheral tissues toward the central nervous system. These neurons establish constant communication with their targets which insures correct maturation and functioning of the somato-sensory nervous system. Interfering with this two-way communication leads to cellular, electrophysiological and molecular modifications that can eventually cause neuropathic conditions. In this study we reveal that FXYD2, which encodes the gamma-subunit of the Na,K-ATPase reported so far to be mainly expressed in the kidney, is induced in the mouse DRGs at postnatal stages where it is restricted specifically to the TrkB-expressing mechanoceptive and Ret-positive/IB4-binding non-peptidergic nociceptive neurons. In non-peptidergic nociceptors, we show that the transcription factor Runx1 controls FXYD2 expression during the maturation of the somato-sensory system, partly through regulation of the tyrosine kinase receptor Ret. Moreover, Ret signaling maintains FXYD2 expression in adults as demonstrated by the axotomy-induced down-regulation of the gene that can be reverted by in vivo delivery of GDNF family ligands. Altogether, these results establish FXYD2 as a specific marker of defined sensory neuron subtypes and a new target of the Ret signaling pathway during normal maturation of the non-peptidergic nociceptive neurons and after sciatic nerve injury

    Identifying the connection between Roman Conceptions of ‘Pure Air’ and Physical and Mental Health in Pompeian Gardens (c. 150 BC-AD 79): A Multi-Sensory Approach to Ancient Medicine

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    Different genres of Roman literature commented on the relationship between the condition of the environment and physical and mental health. They often refer to clear, pure, or good air as a beneficial aspect of the environment. Yet, unlike fetid air, they provide few descriptions of what constituted healthy air quality. Moreover, aside from pointing out the association between the environment and bodily condition, the writers also did not explain precisely how the link between the two was made. This paper utilizes a comparative study of ancient literature and the archaeological remains of Roman gardens in Pompeii: archaeobotanical samples, fresco paintings, location, and surviving features. Three questions are addressed in this study: First, how did the Romans identify and define pure? Second, how did air connect to the body? Third, what were the qualities of pure air and how did they benefit the body? Not only was inhalation a means of linking air to the body, but the two were also related through sensory perception. I argue that sight, sound, and olfaction were used to identify the qualities of pure air. Through the sensory process of identification, the beneficial properties of pure air were, in accordance with ancient perceptions of sensory function, taken into the body and affected health. Thus, sensory perception acted as the bridge between the environment and health

    A Deubiquitylating Complex Required for Neosynthesis of a Yeast Mitochondrial ATP Synthase Subunit

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    The ubiquitin system is known to be involved in maintaining the integrity of mitochondria, but little is known about the role of deubiquitylating (DUB) enzymes in such functions. Budding yeast cells deleted for UBP13 and its close homolog UBP9 displayed a high incidence of petite colonies and slow respiratory growth at 37°C. Both Ubp9 and Ubp13 interacted directly with Duf1 (DUB-associated factor 1), a WD40 motif-containing protein. Duf1 activates the DUB activity of recombinant Ubp9 and Ubp13 in vitro and deletion of DUF1 resulted in the same respiratory phenotype as the deletion of both UBP9 and UBP13. We show that the mitochondrial defects of these mutants resulted from a strong decrease at 37°C in the de novo biosynthesis of Atp9, a membrane-bound component of ATP synthase encoded by mitochondrial DNA. The defect appears at the level of ATP9 mRNA translation, while its maturation remained unchanged in the mutants. This study describes a new role of the ubiquitin system in mitochondrial biogenesis
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