919 research outputs found

    An operations semantics for pure dataflow

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    We prove the equivalence between an operational and an extensional semantics for pure dataflow. The term pure dataflow refers to dataflow nets in which the nodes are functional (i.e. the output history is a function of the input history only) and the arcs are unbounded fifo queues. Gilles Kahn gave a method for the representation of a pure dataflow net as a set of equations; one equation for each arc in the net. We present a complete proof that the operational behaviour of a pure dataflow net is exactly described by the least fixed point solution to its associated set of equations. Our model is completely general since our nodes have the universality property, in that, for any continuous history function there exists a node that will compute it. Moreover since our nets are not built from a set of sequential primitive nodes the model is not in the communicating sequential processes framework. On the contrary our nets have the abstraction property in that any net can be collapsed into a node. The above proof gives complementary ways of viewing pure dataflow nets, that is, as either sets of equations or as graphs. It moreover gives rise to an elegant equational dataflow language. Pure dataflow then takes on an important role since it is a correct implementation for such a functional programming language; nodes being implementation of continuous history functions; arcs and datons being implementations of histories; and nets being mechanisms for computing the solutions to sets of equations

    Alpha synuclein post translational modifications: potential targets for Parkinson’s disease therapy?

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    Parkinson’s disease (PD) is the most common neurodegenerative disorder with motor symptoms. The neuropathological alterations characterizing the brain of patients with PD include the loss of dopaminergic neurons of the nigrostriatal system and the presence of Lewy bodies (LB), intraneuronal inclusions that are mainly composed of alpha-synuclein (α-Syn) fibrils. The accumulation of α-Syn in insoluble aggregates is a main neuropathological feature in PD and in other neurodegenerative diseases, including LB dementia (LBD) and multiple system atrophy (MSA), which are therefore defined as synucleinopathies. Compelling evidence supports that α-Syn post translational modifications (PTMs) such as phosphorylation, nitration, acetylation, O-GlcNAcylation, glycation, SUMOylation, ubiquitination and C-terminal cleavage, play important roles in the modulation α-Syn aggregation, solubility, turnover and membrane binding. In particular, PTMs can impact on α-Syn conformational state, thus supporting that their modulation can in turn affect α-Syn aggregation and its ability to seed further soluble α-Syn fibrillation. This review focuses on the importance of α-Syn PTMs in PD pathophysiology but also aims at highlighting their general relevance as possible biomarkers and, more importantly, as innovative therapeutic targets for synucleinopathies. In addition, we call attention to the multiple challenges that we still need to face to enable the development of novel therapeutic approaches modulating α-Syn PTMs

    Barium alginate capsules for 3D immobilisation of living cells: morphology, membrane properties and permeability

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    Encapsulation in a barium alginate membrane is a promising strategy to obtain a three dimensional culture of living cells: membrane properties are crucial for a realistic clinical application. A one-step encapsulation technique, recently developed for controlled release of boar semen, was employed to prepare barium alginate and protamine-alginate membranes: permeability to two model molecules (haemoglobin and glucose) was evaluated. Capsules were evaluated for technological properties and scanning electron microscopy was used to examine the external morphology of the capsules and the 3D distribution of the cells within the core. The results indicate that 3D arrangement and cell shape are maintained, capsule dimensions and mechanical properties can be modulated, as well as their permeability to model molecules such as haemoglobin and glucose

    Association between a single measurement of progesterone and cortisol blood concentrations at two to one week before parturition, and number of fetuses in the Teramana goat

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    The Teramana goat is an at-risk breed, needing population protection and programs to increase their numbers. The first step for a population increase is the best management of reproduction, leading to an as high as possible number of healthy and viable kids born. To this purpose, beside the optimization of mating, the best possible management of pregnancy and parturition is mandatory. The goat is a prolific farm animal in which single, double, or triple ovulations can occur, leading to singleton, twin or triple pregnancies, and the birth of multiple kids. Twins and triplets are associated to increased risk for perinatal mortality and need a special surveillance and possible assistance at birth. Knowledge of the number of fetuses that have to be delivered from each goat could be a practical tool for a better management of parturition. Among the methods to define the number of fetuses in the goat, the measurement of blood progesterone (P4) concentrations have provided inconsistent results. Therefore, the present study was aimed to assess the possible association between the maternal concentrations of plasma P4 and cortisol (C), two hormones possibly associated to the number of fetuses, measured only once at about two to one week before parturition in Teramana goats, and the number of fetuses. The results, obtained from 23 does, showed that both plasma P4 and C are higher in does bearing multiple fetuses than does with singleton pregnancies. However, the single measurement of plasma C, but not P4, two to one week before the expected parturition in the Teramana goat is useful to distinguish between does bearing singleton and triplet pregnancies for a better surveillance and assistance at delivery. Therefore, it could represent a tool for the best management of reproduction in a breed population at risk for extinctio

    Hair and Claw Dehydroepiandrosterone Concentrations in Newborn Puppies Spontaneously Dead within 30 Days of Age

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    The latest intrauterine fetal developmental stage and the neonatal period represent the most challenging phases for mammalian offspring. Toward the term of pregnancy, during parturition, and after birth, the hypothalamic–pituitary–adrenal axis (HPA) is a key system regulating several physiologic processes, through the production of cortisol and dehydroepiandrosterone (DHEA). This study was aimed to assess DHEA concentrations in hair and claws of 126 spontaneously dead newborn puppies, classified as premature puppies (PRE-P), stillborn puppies (STILL-P) and puppies that died from the 1st to the 30th day of life (NEON-P). The possible influence of newborn sex, breed body size, and timing of death on DHEA concentrations in both matrices was evaluated. Claw DHEA concentrations were higher in the PRE-P group when compared to STILL-P and NEON-P puppies (p < 0.05), whilst no significant differences were found in hair for all the studied factors. The results confirm the hypothesis that higher amounts of DHEA are produced during the intrauterine life in dogs, also in puppies that will die soon after birth

    Postpartum hair cortisol, dehydroepiandrosterone sulfate and their ratio in beef cows: Exploring association with parity and conception outcome

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    Hair steroid measurement has received increasing attention for monitoring hypothalamic-pituitary-adrenal axis function, as it offers the advantages of being noninvasive, fast, and able to indicate steroid concentrations over long periods. The objects of the study were to evaluate cortisol (C) and dehydroepiandrosterone sulfate (DHEA-S) hair concentrations and their ratio (C/DHEA-S) in beef cows from calving to 100 days (d) postpartum (pp) and to assess possible differences related to parity (primiparous vs multiparous) and conception outcome (pregnant vs not pregnant). Hair samples were collected from 6 primiparous and 5 multiparous pregnant beef cows by clipping the coat at calving (T0) and every 20 d for 5 times (T1-T5), collecting only the regrown hair. Starting from the 6th-week pp, cows were submitted to artificial insemination at spontaneous estrus; by 100 d pp, 7 cows were pregnant and 4 were not pregnant. Statistical analysis showed higher hair C concentrations in the 11 cows at calving (T0) compared to all the subsequent samplings except for T1, and higher C concentrations at T1 compared to T3, T4, and T5. These results indicate that hair C concentrations in beef cows are affected by sampling time, with a decrease from calving, as reported in other matrices. When exploring changes within parity groups, no differences were found in the multiparous among sampling times, while hair C concentrations at T0 and T1 tended to be higher than at T2 (0.01 ≀ p < 0.05) and were higher (p < 0.01) than in all the subsequent samplings (T3, T4 and T5) within the primiparous group. Higher hair C concentrations were found at T0 and T1 in the primiparous compared to multiparous (p < 0.01), suggesting that primiparous cows undergo a greater stress level before and around parturition compared to multiparous, probably due to the novelty of the calving experience. No differences were detected in C hair concentrations according to conception outcome (pregnant versus not pregnant) in each sampling time. Hair DHEA-S concentrations were neither affected by time nor by parity or conception outcome. Differences in the C/DHEA-S ratio were found at T1, with higher C/DHEA-S in the multiparous compared to primiparous cows (p < 0.001), and a tendency for higher ratio in the not pregnant compared to the pregnant (0.01 ≀ p < 0.05). These results support the choice of hair as a valuable biological matrix when investigating long-time periods such as postpartum in cows and suggest an enhanced immunoprotective effect of DHEA-S in the postpartum of primiparous cows, and in cows that get pregnant within 100 d postpartum

    Role of Quantum Confinement in Luminescence Efficiency of Group IV Nanostructures

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    Experimental results obtained previously for the photoluminescence efficiency (PLeff_{eff}) of Ge quantum dots (QDs) are theoretically studied. A log⁥\log-log⁥\log plot of PLeff_{eff} versus QD diameter (DD) resulted in an identical slope for each Ge QD sample only when EG∌(D2+D)−1E_{G}\sim (D^2+D)^{-1}. We identified that above D≈D\approx 6.2 nm: EG∌D−1E_{G}\sim D^{-1} due to a changing effective mass (EM), while below D≈D\approx 4.6 nm: EG∌D−2E_{G}\sim D^{-2} due to electron/ hole confinement. We propose that as the QD size is initially reduced, the EM is reduced, which increases the Bohr radius and interface scattering until eventually pure quantum confinement effects dominate at small DD

    How stressful is maternity? Study about cortisol and dehydroepiandrosterone-sulfate coat and claws concentrations in female dogs from mating to 60 days post-partum

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    In dogs, the phase from mating to the end of weaning lasts about 120 days and encompasses many aspects that, interacting, contribute to increase the allostatic load. The coat and claws, useful for long-term change assessments, have the advantage of being collectable without invasiveness. In the present study, the Cortisol (C) and Dehydroepiandrosterone-sulfate (DHEA-S) concentration monthly changes in the coat and claws were studied in female dogs from mating to the end of weaning to assess Hypothalamic\u2013Pituitary\u2013Adrenal (HPA) axis activation during pregnancy and the post-partum period. The results from 15 Dobermann Pinscher female dogs showed a trend of increase of the coat C from mating to 60 days post-partum, with significant changes between mating and parturition-60 days post-partum (p < 0.01) and between the 30-day pregnancy diagnosis (PD) and 30\u201360 days post-partum (p < 0.05). The claws C trend showed significant increases between mating and 30\u201360 days post-partum (p < 0.05) and between the PD and 60 days post-partum (p < 0.01). DHEA-S in both matrices showed non-significant changes. The results suggest that maternity could play a pivotal role in the HPA axis activation, with a subsequent chronic secretion of C determining an increase in the allostatic load in the mothers. Neither maternal parity nor litter size played a significant role in the accumulation of C and DHEA-S in both matrices
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