2,348 research outputs found

    Galactic and Cosmic Type Ia SN rates: is it possible to impose constraints on SNIa progenitors?

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    We compute the Type Ia supernova rates in typical elliptical galaxies by varying the progenitor models for Type Ia supernovae. To do that a formalism which takes into account the delay distribution function (DTD) of the explosion times and a given star formation history is adopted. Then the chemical evolution for ellipticals with baryonic initial masses 101010^{10}, 101110^{11} and 1012M⊙10^{12} M_{\odot} is computed, and the mass of Fe produced by each galaxy is precisely estimated. We also compute the expected Fe mass ejected by ellipticals in typical galaxy clusters (e.g. Coma and Virgo), under different assumptions about Type Ia SN progenitors. As a last step, we compute the cosmic Type Ia SN rate in an unitary volume of the Universe by adopting several cosmic star formation rates and compare it with the available and recent observational data. Unfortunately, no firm conclusions can be derived only from the cosmic SNIa rate, neither on SNIa progenitors nor on the cosmic star formation rate. Finally, by analysing all our results together, and by taking into account previous chemical evolution results, we try to constrain the best Type Ia progenitor model. We conclude that the best progenitor models for Type Ia SNe are still the single degenerate model, the double degenerate wide model, and the empirical bimodal model. All these models require the existence of prompt Type Ia supernovae, exploding in the first 100 Myr since the beginning of star formation, although their fraction should not exceed 15-20% in order to fit chemical abundances in galaxies.Comment: 17 pages, 11 figures, Submitted to MNRA

    An Atypical Cutaneous Reaction to Rivastigmine Transdermal Patch

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    Rivastigmine is a cholinesterase inhibitor which improves cognitive function and is currently being used in patients with mild to moderate Parkinson's and Alzheimer's dementia. This drug can be given orally or topically, as transdermal patch. The latter form is currently used for most excellent compliance and few side effects. The most common cutaneous side effects are irritative dermatitis. We report the second case of active sensitization by the rivastigmine-patch in a patient suffering from Alzheimer's dementia

    Melatonin Supplementation Improves Glycemic Control While Lowering Oxidative Stress in Type 2 Diabetes

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    The purpose of this investigation was to evaluate the effect of melatonin on glycemic control and oxidative stress (OS) in adults with type 2 diabetes (T2D). Fourteen subjects with T2D (10 female, 4 male; 52.5 ± 5.0 years) were randomly assigned to melatonin (MEL) or placebo groups (PLA) for 42 days, in a crossover design. Subjects ingested 10 mg of MEL or an identical placebo (PLA) 30 minutes prior to sleep. Fasting blood draws occurred at baseline, 42 days, and 84 days. Plasma malondialdehyde, a marker of OS, significantly decreased on MEL (-6.25±2.10 nmol/ml) compared to PLA (0.72±3.30, p=0.028). The change in hemoglobin A1c showed a total improvement of 0.33% following MEL supplementation compared to PLA (-0.24±0.23 % for MEL vs. 0.09±0.21 % for PLA, p=0.01), although no significant changes were noted in fasting plasma glucose or lipid levels. Daily melatonin may diminish OS and enhance glycemic control in adults with T2D

    A Reference Architecture for Management of Security Operations in Digital Service Chains

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    Modern computing paradigms (i.e., cloud, edge, Internet of Things) and ubiquitous connectivity have brought the notion of pervasive computing to an unforeseeable level, which boosts service-oriented architectures and microservices patterns to create digital services with data-centric models. However, the resulting agility in service creation and management has not been followed by a similar evolution in cybersecurity patterns, which still largely rest on more conventional device- and infrastructure-centric models. In this Chapter, we describe the implementation of the GUARD Platform, which represents the core element of a modern cybersecurity framework for building detection and analytics services for complex digital service chains. We briefly review the logical components and how they address scientific and technological challenges behind the limitations of existing cybersecurity tools. We also provide validation and performance analysis that show the feasibility and efficiency of our implementation

    Cooperation and Self-Regulation in a Model of Agents Playing Different Games

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    A simple model for cooperation between "selfish" agents, which play an extended version of the Prisoner's Dilemma(PD) game, in which they use arbitrary payoffs, is presented and studied. A continuous variable, representing the probability of cooperation, pk(t)∈p_k(t) \in [0,1], is assigned to each agent kk at time tt. At each time step tt a pair of agents, chosen at random, interact by playing the game. The players update their pk(t)p_k(t) using a criteria based on the comparison of their utilities with the simplest estimate for expected income. The agents have no memory and use strategies not based on direct reciprocity nor 'tags'. Depending on the payoff matrix, the systems self-organizes - after a transient - into stationary states characterized by their average probability of cooperation pˉeq\bar{p}_{eq} and average equilibrium per-capita-income pˉeq,Uˉ∞\bar{p}_{eq},\bar{U}_\infty. It turns out that the model exhibit some results that contradict the intuition. In particular, some games which - {\it a priory}- seems to favor defection most, may produce a relatively high degree of cooperation. Conversely, other games, which one would bet that lead to maximum cooperation, indeed are not the optimal for producing cooperation.Comment: 11 pages, 3 figures, keybords: Complex adaptive systems, Agent-based models, Social system

    Novel anti-inflammatory and chondroprotective effects of the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride and human melanocortin MC3 receptor agonist PG-990 on lipopolysaccharide activated chondrocytes

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    Human melanocortin MC1 and MC3 receptors expressed on C-20/A4 chondrocytes exhibit chondroprotective and anti-inflammatory effects when activated by melanocortin peptides. Nearly 9 million people in the UK suffer from osteoarthritis, and bacterial infections play a role in its development. Here, we evaluate the effect of a panel of melanocortin peptides with different selectivity for human melanocortin MC1 (α-MSH, BMS-470539 dihydrochloride) and MC3 ([DTrp8]-Îł-MSH, PG-990) receptors and C-terminal peptide α-MSH11-13(KPV), on inhibiting LPS-induced chondrocyte death, pro-inflammatory mediators and induction of anti-inflammatory proteins. C-20/A4 chondrocytes were treated with a panel of melanocortin peptides prophylactically and therapeutically in presence of LPS (0.1 ÎŒg/ml). The chondroprotective properties of these peptides determined by cell viability assay, RT-PCR, ELISA for detection of changes in inflammatory markers (IL-6, IL-8 and MMP-1, -3 and -13) and western blotting for expression of the anti-inflammatory protein heme-oxygenase-1. C-20/A4 expressed human melanocortin MC1 and MC3 receptors and melanocortin peptides elevated cAMP. LPS stimulation caused a reduction in C-20/A4 viability, attenuated by the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride, and MC3 receptor agonists PG-990 and [DTrp8]-Îł-MSH. Prophylactic and therapeutic regimes of [DTrp8]-Îł-MSH significantly inhibited LPS-induced modulation of cartilage-damaging IL-6, IL-8, MMPs −1,-3 and −13 mediators both prophylactically and therapeutically, whilst human melanocortin MC1 and MC3 receptor agonists promoted an increase in HO-1 production. In the presence of LPS, activation of human melanocortin MC1 and MC3 receptors provided potent chondroprotection, upregulation of anti-inflammatory proteins and downregulation of inflammatory and proteolytic mediators involved in cartilage degradation, suggesting a new avenue for osteoarthritis treatment

    Role for Non-Proteolytic Control of M-phase Promoting Factor Activity at M-phase Exit

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    M-phase Promoting Factor (MPF; the cyclin B-cdk 1 complex) is activated at M-phase onset by removal of inhibitory phosphorylation of cdk1 at thr-14 and tyr-15. At M-phase exit, MPF is destroyed by ubiquitin-dependent cyclin proteolysis. Thus, control of MPF activity via inhibitory phosphorylation is believed to be particularly crucial in regulating transition into, rather than out of, M-phase. Using the in vitro cell cycle system derived form Xenopus eggs, here we show, however, that inhibitory phosphorylation of cdk1 contributes to control MPF activity during M-phase exit. By sampling extracts at very short intervals during both meiotic and mitotic exit, we found that cyclin B1-associated cdk1 underwent transient inhibitory phosphorylation at tyr-15 and that cyclin B1-cdk1 activity fell more rapidly than the cyclin B1 content. Inhibitory phosphorylation of MPF correlated with phosphorylation changes of cdc25C, the MPF phosphatase, and physical interaction of cdk1 with wee1, the MPF kinase, during M-phase exit. MPF down-regulation required Ca(++)/calmodulin-dependent kinase II (CaMKII) and cAMP-dependent protein kinase (PKA) activities at meiosis and mitosis exit, respectively. Treatment of M-phase extracts with a mutant cyclin B1-cdk1AF complex, refractory to inhibition by phosphorylation, impaired binding of the Anaphase Promoting Complex/Cyclosome (APC/C) to its co-activator Cdc20 and altered M-phase exit. Thus, timely M-phase exit requires a tight coupling of proteolysis-dependent and proteolysis-independent mechanisms of MPF inactivation

    Comparison of cloud products within IASI footprints for the assimilation of cloudy radiances

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    This article compares different methods of deriving cloud properties in the footprint of the Infrared Atmospheric Sounding Interferometer (IASI), onboard the European MetOp satellite. Cloud properties produced by ten operational schemes are assessed and an intercomparison of the products for a 12 h global acquisition is presented. Clouds cover a large part of the Earth, contaminating most of the radiance data. The estimation of cloud top height and effective amount within the sounder footprint is an important step towards the direct assimilation of cloud-affected radiances. This study first examines the capability of all the schemes to detect and characterize the clouds for all complex situations and provides some indications of confidence in the data. Then the dataset is restricted to thick overcast single layers and the comparison shows a significant agreement between all the schemes. The impact of the retrieved cloud properties on the residuals between calculated cloudy radiances and observations is estimated in the long-wave part of the spectrum

    Renal involvement in HCV related cirrhosis evidenced as glomerular and tubular derangement

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    Introduction and Aims: The relation between HCV infection and glomerular damage is well recognized, with evidences of negative impact on renal function. HCV replication in renal tubular cells on kidney biopsies has been reported but very limited data are available on HCV-mediated tubular damage. The aim of the study was to assess the presence of renal involvement (RI), glomerular or tubular, in patients with HCV cirrhosis. Methods: 98 patients with HCV cirrhosis Child Pugh-A were consecutively enrolled. Glomerular filtration rate (eGFR) was estimated with CKD-EPI 2009 equation. Urinary albumin/creatinine (ACR) and alpha1microglobulin/creatinine (a1MCR) ratios were calculated. Glomerular involvement was defined based on ACR>20ÎŒg/mg, tubular involvement based on a1MCR>14ÎŒg/mg plus fractional sodium excretion (FeNa)>1%. Urine concentration of Liver-type Fatty Acid-Binding Protein (L-FABP) and Kidney injury molecule-1 (KIM-1) were examined in morning midstream urine samples (ELISA) and the values normalized to urine creatinine concentration as expression of tubular derangement. Results: eGFR was ≄60 mL/min/1.73 m2 in 92 patients (93.8%) and between 45-59 mL/min/1.73 m2 in 6 patients (6.1%). Glomerular involvement was found in 19 patients (19.4%), tubular involvement in 31 patients (31.6%) and these co-occurred in 10 patients ( p=0.034). Patients with glomerular or tubular involvement, or both, considered as patients with RI, showed significantly lower eGFR values ( p=0.005) (Tab 1). A ROC curve was drafted and a cut point of 90 ml/min predicted RI (AUC: 0.700; sensitivity 63%, specificity 75%). Patients with RI were older, had higher ACR and a1MCR levels and exhibited a higher KDIGO stage (Tab 1). No association was found between RI and: HCV-RNA levels, liver stiffness and liver function tests. L-FABP and KIM-1 levels were significantly higher in patients with RI. Conclusions: Tubular and/or glomerular involvement is quite frequent in HCV cirrhotic patients, despite a normal eGFR. The evidence of tubular involvement suggests an alternative localization of HCV as renal disease

    The upstream Variable Number Tandem Repeat polymorphism of the monoamine oxidase type A gene influences trigeminal pain-related evoked responses

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    Monoamines have an important role in neural plasticity, a key factor in cortical pain processing that promotes changes in neuronal network connectivity. Monoamine oxidase type A (MAOA) is an enzyme that, due to its modulating role in monoaminergic activity, could play a role in cortical pain processing. The X-linked MAOA gene is characterized by an allelic variant of length, the MAOA upstream Variable Number Tandem Repeat (MAOA-uVNTR) region polymorphism. Two allelic variants of this gene are known, the high-activity MAOA (HAM) and low-activity MAOA (LAM). We investigated the role of MAOA-uVNTR in cortical pain processing in a group of healthy individuals measured by the trigeminal electric pain-related evoked potential (tPREP) elicited by repeated painful stimulation. A group of healthy volunteers was genotyped to detect MAOA-uVNTR polymorphism. Electrical tPREPs were recorded by stimulating the right supraorbital nerve with a concentric electrode. The N2 and P2 component amplitude and latency as well as the N2-P2 inter-peak amplitude were measured. The recording was divided into three blocks, each containing 10 consecutive stimuli and the N2-P2 amplitude was compared between blocks. Of the 67 volunteers, 37 were HAM and 30 were LAM. HAM subjects differed from LAM subjects in terms of amplitude of the grand-averaged and first-block N2-P2 responses (HAM>LAM). The N2-P2 amplitude decreased between the first and third block in HAM subjects but not LAM subjects. The MAOA-uVNTR polymorphism seemed to influence the brain response in a repeated tPREP paradigm and suggested a role of the MAOA as a modulator of neural plasticity related to cortical pain processing
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