431 research outputs found
Baryogenesis and Leptogenesis from Supercooled Confinement
We propose a framework of baryogenesis and leptogenesis that relies on a
supercooled confining phase transition (PT) in the early universe. The baryon
or lepton asymmetry is sourced by decays of hadrons of the strong dynamics
after the PT, and it is enhanced compared to the non-confining case, which was
the only one explored so far. This widens the energy range of the PT, where the
observed baryon asymmetry can be reproduced, down to the electroweak scale. The
framework then becomes testable with gravity waves (GW) at LISA and the
Einstein Telescope. We then study two explicit realisations: one of
leptogenesis from composite sterile neutrinos that realises inverse see-saw;
one of baryogenesis from composite scalars that is partly testable by existing
colliders and flavour factories.Comment: 34 pages, 9 figures, minor revision, accepted for publication in JHE
Interaction between stress and addiction: Contributions from Latin-American neuroscience
Drug addiction is a chronic neuropsychiatric disorder that escalates from an initial exposure to drugs of abuse, such as cocaine, cannabis, or heroin, to compulsive drug-seeking and intake, reduced ability to inhibit craving-induced behaviors, and repeated cycles of abstinence and relapse. It is well-known that chronic changes in the brain's reward system play an important role in the neurobiology of addiction. Notably, environmental factors such as acute or chronic stress affect this system, and increase the risk for drug consumption and relapse. Indeed, the HPA axis, the autonomic nervous system, and the extended amygdala, among other brain stress systems, interact with the brain's reward circuit involved in addictive behaviors. There has been a growing interest in studying the molecular, cellular, and behavioral mechanisms of stress and addiction in Latin-America over the last decade. Nonetheless, these contributions may not be as strongly acknowledged by the broad scientific audience as studies coming from developed countries. In this review, we compile for the first time a series of studies conducted by Latin American-based neuroscientists, who have devoted their careers to studying the interaction between stress and addiction, from a neurobiological and clinical perspective. Specific contributions about this interaction include the study of CRF receptors in the lateral septum, investigations on the neural mechanisms of cross-sensitization for psychostimulants and ethanol, the identification of the Wnt/?-catenin pathway as a critical neural substrate for stress and addiction, and the emergence of the cannabinoid system as a promising therapeutic target. We highlight animal and human studies, including for instance, reports coming from Latin American laboratories on single nucleotide polymorphisms in stress-related genes and potential biomarkers of vulnerability to addiction, that aim to bridge the knowledge from basic science to clinical research. © 2018 Torres-Berrio, Cuesta, Lopez-Guzman and Nava-Mesa
Source Apportionment of PM2.5 in Florence (Italy) by PMF Analysis of Aerosol Composition Records
An extensive field campaign was carried out in Florence (Tuscany) to investigate the PM2.5 composition and to identify its sources. The scientific objective of this study is providing a reliable source apportionment, which is mandatory for the application of effective mitigation actions. Particulate matter (PM) was collected for one year, simultaneously in a traffic site, in an urban background, and in a regional background site. While the use of two filter types (quartz and Teflon) allowed obtaining a comprehensive chemical characterization (elemental and organic carbon, ions, elements) by the application of different analytical techniques, the location of the three sampling sites allowed getting a better separation among local, urban, regional and transboundary sources. During shorter periods, the aerosol was also collected by means of a streaker sampler and PIXE (Particle Induced X-ray Emission) analysis of these samples allowed the assessment of hourly resolution elemental time trends. Positive matrix factorisation (PMF) identified seven main sources: traffic, biomass burning, secondary sulphate, secondary nitrates, urban dust, Saharan dust and marine aerosol. Traffic mass concentration contributions were found to be strong only at the traffic site (~8 μg·m−3, 33% of PM2.5). Biomass burning turned out to be an important PM2.5 source in Florence (~4 μg·m−3), with very similar weights in both city sites while at the regional background site its weight was negligible. Secondary sulphate is an important PM2.5 source on a regional scale, with comparable values in all three sites (~3.5 μg·m−3). On average, the contribution of the "natural" components (e.g., mineral dust and marine aerosols) to PM2.5 is moderate (~1 μg·m−3) except during Saharan dust intrusions where this contribution is higher (detected simultaneously in all three sites). High-time resolution data confirmed and reinforced these results
Hypertension in Metabolic Syndrome: Vascular Pathophysiology
Metabolic syndrome is a cluster of metabolic and cardiovascular symptoms: insulin resistance (IR), obesity, dyslipemia. Hypertension and vascular disorders are central to this syndrome. After a brief historical review, we discuss the role of sympathetic tone. Subsequently, we examine the link between endothelial dysfunction and IR. NO is involved in the insulin-elicited capillary vasodilatation. The insulin-signaling pathways causing NO release are different to the classical. There is a vasodilatory pathway with activation of NO synthase through Akt, and a vasoconstrictor pathway that involves the release of endothelin-1 via MAPK. IR is associated with an imbalance between both pathways in favour of the vasoconstrictor one. We also consider the link between hypertension and IR: the insulin hypothesis of hypertension. Next we discuss the importance of perivascular adipose tissue and the role of adipokines that possess vasoactive properties. Finally, animal models used in the study of vascular function of metabolic syndrome are reviewed. In particular, the Zucker fatty rat and the spontaneously hypertensive obese rat (SHROB). This one suffers macro- and microvascular malfunction due to a failure in the NO system and an abnormally high release of vasoconstrictor prostaglandins, all this alleviated with glitazones used for metabolic syndrome therapy
Saharan dust impact in central Italy: An overview on three years elemental data records
In southern European countries, Saharan dust may episodically produce significant increases of PM10, which may also cause the exceedance of the PM10 daily limit value established by the European Directive (2008/50/EC). The detection with very high sensitivity of all the elements that constitute mineral dust makes PIXE technique a very effective tool to assess the actual impact of these episodes.
In this work, a review of long-term series of elemental concentrations obtained by PIXE has been accomplished with the aim of identifying the occurrence of Saharan dust transport episodes over long periods in Tuscany and characterising them in terms of composition and impact on PM concentration, tracing back their contribution to the exceedances of the PM10 limit value.
The impact of the different Saharan intrusions on PM10 showed a very high variability. During the most intense episodes (which occurred with a frequency of few times per year) the calculated soil dust concentration reached values as high as 25\u201330 \u3bcg m 123, to be compared with background values of the order of 5 \u3bcg m 123. The Saharan dust contribution was decisive to cause the exceedance of the PM10 daily limit value in the 1\u20132% of the days considered in the present work
Assessment of potential source regions of PM2.5 components at a southwestern Mediterranean site
A set of PM 2.5 samples ( n = 121) collected at an urban background location in Elche (in southeastern Spain) from December 2004 to November 2005 was analysed by particle-induced X-ray emission (PIXE) and ion chromatography in order to provide source identification and potential source locations. Positive matrix factorization (PMF) was used to estimate source profiles and their mass contributions. The PMF modelling identified six sources: aged sea salt (9.2%), ammonium sulphate (40.4%), soil dust related to Saharan outbreaks (13.0%), traffic 1 (18.9%), nitrate aerosol and traffic 2 (5.5%) and local soil dust (6.0%). Potential source contribution function (PSCF) was then used to identify potential source locations. Scarce influence from Mediterranean and European regions was found with the exception of the nitrate source, whose potential source areas were northern Italy and eastern France. Primary source regions for the remaining components (ammonium sulphate, soil dust-related to Saharan outbreaks and aged sea salt) with known mass contributions due to long-range transport have a marked Atlantic and North African location, primarily between Morocco and northwestern Algeria. DOI: 10.1111/j.1600-0889.2010.00510.
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