4,760 research outputs found

    The Greek Crisis: Causes and Consequences

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    Greece has reached a point where, under any plausible macroeconomic scenario, public debt will continue growing faster than GDP. Fiscal consolidation alone cannot close the solvency gap. A substantial reduction in the stock of debt is needed. Even post-debt restructuring, there is no guarantee that the government will succeed in its dual goal of restoring fiscal solvency and closing the competitiveness gap. Yet we think Greece stands a better chance of accomplishing these goals from inside the EMU rather than outside it. This chapter takes stock of the factors that led to the explosion of public debt, the loss of competitiveness, and the failure of the first EU-IMF programme. We also present our views on the likely debt restructuring (and post-restructuring) scenarios.

    Asymmetric core combustion in neutron stars and a potential mechanism for gamma ray bursts

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    We study the transition of nuclear matter to strange quark matter (SQM) inside neutron stars (NSs). It is shown that the influence of the magnetic field expected to be present in NS interiors has a dramatic effect on the propagation of a laminar deflagration (widely studied so far), generating a strong acceleration of the flame in the polar direction. This results in a strong asymmetry in the geometry of the just formed core of hot SQM which resembles a cylinder orientated in the direction of the magnetic poles of the NS. This geometrical asymmetry gives rise to a bipolar emission of the thermal neutrino-antineutrino pairs produced in the process of SQM formation. The neutrino-antineutrino pairs annihilate into electron-positron pairs just above the polar caps of the NS giving rise to a relativistic fireball, thus providing a suitable form of energy transport and conversion to gamma emission that may be associated to short gamma ray bursts (GRBs).Comment: 2 figure

    Pharmacology and clinical drug candidates in redox medicine

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    SIGNIFICANCE Oxidative stress is suggested to be a disease mechanism common to a wide range of disorders affecting human health. However, so far, the pharmacotherapeutic exploitation of this, for example, based on chemical scavenging of pro-oxidant molecules, has been unsuccessful. Recent Advances: An alternative emerging approach is to target the enzymatic sources of disease-relevant oxidative stress. Several such enzymes and isoforms have been identified and linked to different pathologies. For some targets, the respective pharmacology is quite advanced, that is, up to late-stage clinical development or even on the market; for others, drugs are already in clinical use, although not for indications based on oxidative stress, and repurposing seems to be a viable option. CRITICAL ISSUES For all other targets, reliable preclinical validation and drug ability are key factors for any translation into the clinic. In this study, specific pharmacological agents with optimal pharmacokinetic profiles are still lacking. Moreover, these enzymes also serve largely unknown physiological functions and their inhibition may lead to unwanted side effects. FUTURE DIRECTIONS The current promising data based on new targets, drugs, and drug repurposing are mainly a result of academic efforts. With the availability of optimized compounds and coordinated efforts from academia and industry scientists, unambiguous validation and translation into proof-of-principle studies seem achievable in the very near future, possibly leading towards a new era of redox medicine

    Examination of stick-slip scenario on lubricated spring-brake systems

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    Several complex mechanisms can be responsible for undesirable friction-induced vibrations in many mechanical systems. This paper presents a tribological and dynamic analysis of the stick-slip problem, under greased lubrication, taking into account the practical application of a spring-brake system used in electric tubular motors. The main functioning of these brakes is based on the frictional greased contact between a stationary cylinder and a torsional spring, which rotates inside it. The identification of the parameters that most affect the stick-slip appearance in greased contacts requires a complete understanding and appropriate analysis of the entire system, to identify the effects of all physical parameters on the system. Here the global dynamics and the local contact behaviour is analysed, providing an in-depth examination of the stick-slip phenomenon on a greased contact

    Microfluidic platform for electrophysiological studies on Xenopus laevis oocytes under varying gravity levels

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    Voltage clamp measurements reveal important insights into the activity of membrane ion channels. While conventional voltage clamp systems are available for laboratory studies, these instruments are generally unsuitable for more rugged operating environments. In this study, we present a non-invasive microfluidic voltage clamp system developed for the use under varying gravity levels. The core component is a multilayer microfluidic device that provides an immobilisation site for Xenopus laevis oocytes on an intermediate layer, and fluid and electrical connections from either side of the cell. The configuration that we term the asymmetrical transoocyte voltage clamp (ATOVC) also permits electrical access to the cytosol of the oocyte without physical introduction of electrodes by permeabilisation of a large region of the oocyte membrane so that a defined membrane patch can be voltage clamped. The constant low level air pressure applied to the oocyte ensures stable immobilisation, which is essential for keeping the leak resistance constant even under varying gravitational forces. The ease of oocyte mounting and immobilisation combined with the robustness and complete enclosure of the fluidics system allow the use of the ATOVC under extreme environmental conditions, without the need for intervention by a human operator. Results for oocytes over-expressing the epithelial sodium channel (ENaC) obtained under laboratory conditions as well as under conditions of micro- and hypergravity demonstrate the high reproducibility and stability of the ATOVC system under distinct mechanical scenarios

    Mitochondrial Complex III Deficiency Caused by TTC19 Defects : Report of a Novel Mutation and Review of Literature

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    We report about a patient with infantile-onset neurodegenerative disease associated with isolated mitochondrial respiratory chain complex III (cIII) deficiency. The boy, now 13 years old, presented with language regression and ataxia at 4 years of age and then showed a progressive course resulting in the loss of autonomous gait and speaking during the following 2 years. Brain MRI disclosed bilateral striatal necrosis. Sequencing of a panel containing nuclear genes associated with cIII deficiency revealed a previously undescribed homozygous rearrangement (c.782_786delinsGAAAAG) in TTC19 gene, which results in a frameshift with premature termination (p.Glu261Glyfs(*)8). TTC19 protein was absent in patient's fibroblasts. TTC19 encodes tetratricopeptide 19, a putative assembly factor for cIII. To date TTC19 mutations have been reported only in few cases, invariably associated with cIII deficiency, but presenting heterogeneous clinical phenotypes. We reviewed the genetic, biochemical, clinical and neuroradiological features of TTC19 mutant patients described to date

    Cranial ultrasound screening in term and late preterm neonates born by vacuum-assisted delivery: Is itworthwhile?

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    Background: Vacuum extraction is the most common choice to assist vaginal delivery, but there are still concerns regarding the neonatal injuries it may cause. This study aimed to evaluate the rate of intracranial injuries assessed by cranial ultrasound (cUS) among infants born by vacuum extraction, and the relationship with maternal and perinatal factors. Methods: This was a single-center retrospective study carried out in a level-3 neonatal unit. A total of 593 term and late preterm infants born by vacuum-assisted delivery were examined with a cUS scan within 3 days after birth. Results: Major head injuries were clinically silent and occurred in 2% of the infants, with a rate of intracranial haemorrhage of 1.7%. Regardless of obstetric factors, the risk of cranial injury was increased in infants requiring resuscitation at birth (p = 0.04, OR 4.1), admitted to NICU (p = 0.01, OR 5.5) or with perinatal asphyxia (p < 0.01, OR 21.3). Maternal age ≥40 years correlated both with adverse perinatal outcomes (p < 0.05) and the occurrence of major injury (p = 0.02, OR 4.6). Conclusion: Overall, vacuum extraction is a safe procedure for neonates. Head injuries are usually mild and asymptomatic, and with spontaneous recovery. However, the rate of major cranial injuries in our cohort warrants further investigation to support a cUS screening, particularly for infants requiring respiratory support at birth. Also, maternal age might be taken into account when evaluating the risk for neonatal complications after vacuum application

    Elemental abundance differences in the 16 Cygni binary system: a signature of gas giant planet formation?

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    The atmospheric parameters of the components of the 16Cygni binary system, in which the secondary has a gas giant planet detected, are measured accurately using high quality observational data. Abundances relative to solar are obtained for 25 elements with a mean error of 0.023 dex. The fact that 16CygA has about four times more lithium than 16CygB is normal considering the slightly different masses of the stars. The abundance patterns of 16CygA and B, relative to iron, are typical of that observed in most of the so-called solar twin stars, with the exception of the heavy elements (Z>30), which can, however, be explained by Galactic chemical evolution. Differential (A-B) abundances are measured with even higher precision (0.018 dex, on average). We find that 16CygA is more metal-rich than 16CygB by 0.041+/-0.007 dex. On an element-to-element basis, no correlation between the A-B abundance differences and dust condensation temperature (Tc) is detected. Based on these results, we conclude that if the process of planet formation around 16CygB is responsible for the observed abundance pattern, the formation of gas giants produces a constant downwards shift in the photospheric abundance of metals, without a Tc correlation. The latter would be produced by the formation of terrestrial planets instead, as suggested by other recent works on precise elemental abundances. Nevertheless, a scenario consistent with these observations requires the convective envelopes of 1 Msun stars to reach their present-day sizes about three times quicker than predicted by standard stellar evolution models.Comment: ApJ, in pres
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