10,593 research outputs found
Experimental effects on dynamics and thermodynamics in nuclear reactions on the symmetry energy as seen by the CHIMERA 4 detector
Heavy ion collisions have been widely used in the last decade to constraint
the parameterizations of the symmetry energy term of nuclear equation of state
(EOS) for asymmetric nuclear matter as a function of baryonic density. In the
Fermi energy domain one is faced with variations of the density within a narrow
range of values around the saturation density =0.16 fm down
towards sub-saturation densities. The experimental observables which are
sensitive to the symmetry energy are constructed starting from the detected
light particles, clusters and heavy fragments that, in heavy ion collisions,
are generally produced by different emission mechanisms at different stages and
time scales of the reaction. In this review the effects of dynamics and
thermodynamics on the symmetry energy in nuclear reactions are discussed and
characterized using an overview of the data taken so far with the CHIMERA
multi-detector array.Comment: 21 pages, 25 figures. Review to appear in EPJA special volume on
nuclear symmetry energ
Access to particle-particle emitting sources at intermediate energies
The study of nuclear matter under extreme conditions is a very active area in nuclear physics. This study may improve our understanding of the equation of states and liquid-gas phase transitions in nuclear matter as well as the
spectroscopic and dynamic characterization of exotic nuclear systems and reactions. A clear characterization of nuclear interacting systems requires probing the spacetime
properties of various particle-emitting sources and the knowledge of the reaction mechanism. Particle-particle correlations represent a very powerful technique to study emitting sources produced during a reaction. In this work two-proton correlation functions measured in Xe+Au at E = 50MeV/nucleon have been studied. By using angle-averaged two-proton correlation functions and imaging techniques we have estimated some of the basic proprieties, such as the size and the relative contributions provided by two-particle–emitting sources produced in semi-central collisions and characterized by different emission time-scales
The blue sky of GJ3470b: the atmosphere of a low-mass planet unveiled by ground-based photometry
GJ3470b is a rare example of a "hot Uranus" transiting exoplanet orbiting a
nearby M1.5 dwarf. It is of crucial interest for atmospheric studies because it
is one of the most inflated low-mass planets known, bridging the boundary
between "super-Earths" and Neptunian planets. We present two new ground-based
light curves of GJ3470b gathered by the LBC camera at the Large Binocular
Telescope. Simultaneous photometry in the ultraviolet (lambda_c = 357.5 nm) and
optical infrared (lambda_c = 963.5 nm) allowed us to detect a significant
change of the effective radius of GJ3470b as a function of wavelength. This can
be interpreted as a signature of scattering processes occurring in the
planetary atmosphere, which should be cloud-free and with a low mean molecular
weight. The unprecedented accuracy of our measurements demonstrates that the
photometric detection of Earth-sized planets around M dwarfs is achievable
using 8-10m size ground-based telescopes. We provide updated planetary
parameters, and a greatly improved orbital ephemeris for any forthcoming study
of this planet.Comment: 8 pages, 6 figures, 1 table; accepted for publication in A&
A novel combinatorial technique for simultaneous quantification of oxygen radicals and aggregation reveals unexpected redox patterns in the activation of platelets by different physiopathological stimuli
This is the author accepted manuscript. The final version is available fromFerrata Storti Foundation via the DOI in this recordThe regulation of platelets by oxidants is critical for vascular health and may explain thrombotic complications in diseases such as diabetes and dementia, but remains poorly understood. Here, we describe a novel technique combining electron paramagnetic resonance spectroscopy and turbidimetry, which has been utilised to monitor simultaneously platelet activation and oxygen radical generation. This technique has been used to investigate the redox-dependence of human and mouse platelets. Using selective peptide inhibitors of NOXs on human platelets and genetically modified mouse platelets (NOX1-/- or NOX2-/-), we discovered that:1) intracellular but not extracellular superoxide anion generated by NADPH oxidases (NOXs) is critical for platelet activation by collagen; 2) superoxide dismutation to hydrogen peroxide is required for thrombin-dependent activation; 3) NOX1 is the main source of oxygen radicals in response to collagen, while NOX2 is critical for activation by thrombin; 4) two platelet modulators, namely oxidised low density lipoproteins (oxLDL) and amyloid peptide β (Aβ), require activation of both NOX1 and NOX2 to pre-activate platelets. This study provides new insights on the redox dependence of platelet activation. It suggests the possibility of selectively inhibiting platelet agonists by targeting either NOX1 (for collagen) or NOX2 (for thrombin). Selective inhibition of either NOX1 or NOX2 impairs the potentiatory effect of tested platelet modulators (oxLDL and Aβ), but does not completely abolish platelet haemostatic function. This information offers new opportunities for the development of disease specific antiplatelet drugs with limited bleeding side effects by selectively targeting one NOX isoenzyme.British Heart Foundatio
Stolon Mass and Classes in White Clover (\u3ci\u3eTrifolium repens\u3c/i\u3e L.) with Two Soil Water Availability Levels
Two trials were carried out to study the stolon mass and classes in white clover (Trifolium repens L.) under two soil water availability levels in summer. In each trial, treatments were two white clover cultivars. From December 15th to February 15th in 1993/94 and again during the same period the following year, white clover was grown under 30 to 70 % (Forced water uptake) or 85-to100 % (Maximum water uptake) of field capacity. Every two months, throughout two years, total stolon mass, and buried, superficial, and aerial stolons were measured. Differences between cultivars were detected in stolon mass and percentage of each stolon class in both trials
Pulse shape discrimination of plastic scintillator EJ 299-33 with radioactive sources
The present study has been carried out in order to investigate about the possibility of using EJ 299-33 scintillator in a multi-detector array to detect neutrons along with light charged particles. In a reaction induced by stable and exotic heavy-ions beams, where copious production of neutrons and other light charged particles occurs, discrimination with low identification threshold of these particles are of great importance. In view of this, EJ 299-33 scintillator having dimension of 3 cm × 3 cm × 3 cm backed by a photomultiplier tube was tested and used under vacuum to detect neutrons, gamma-rays and alpha particles emitted by radioactive sources. Anode pulses from the photomultiplier tube were digitized through GET electronics, recorded and stored in a data acquisition system for the purpose of an off-line analysis. The measurements, under vacuum and low background conditions, show good pulse shape discrimination properties characterized by low identification threshold for neutrons, gamma-rays and alpha particles. The Figures of Merit for neutron-gamma and alpha particles-gamma discriminations have been evaluated together with the energy resolution for gamma-ray and alpha particles
Stolon Growth and Its Morphological Components in White Clover (\u3ci\u3eTrifolium repens\u3c/i\u3e L.) Cultivars
A trial was performed to study the seasonal changes in stolon growth and its morphological components in four white clover cultivars, in the north of Buenos Aires Province, in Argentina. Stolons were tagged in four seasonal measurements periods per year, during two consecutive years. Leaf, stolon and flowerheads weights were recorded at regular intervals in each measurement period and total stolon growth was calculated. Differences among cultivars were found in stolon growth and its morphological components in most of the measurement periods. In spring and summer, differences among cultivars in stolon growth were related to flowering quantity and earliness, and cultivar response to the environment. In autumn and winter, differences were associated to the ability of cultivars to grow at low temperatures
Markov Chain Beam Randomization: a study of the impact of PLANCK beam measurement errors on cosmological parameter estimation
We introduce a new method to propagate uncertainties in the beam shapes used
to measure the cosmic microwave background to cosmological parameters
determined from those measurements. The method, which we call Markov Chain Beam
Randomization, MCBR, randomly samples from a set of templates or functions that
describe the beam uncertainties. The method is much faster than direct
numerical integration over systematic `nuisance' parameters, and is not
restricted to simple, idealized cases as is analytic marginalization. It does
not assume the data are normally distributed, and does not require Gaussian
priors on the specific systematic uncertainties. We show that MCBR properly
accounts for and provides the marginalized errors of the parameters. The method
can be generalized and used to propagate any systematic uncertainties for which
a set of templates is available. We apply the method to the Planck satellite,
and consider future experiments. Beam measurement errors should have a small
effect on cosmological parameters as long as the beam fitting is performed
after removal of 1/f noise.Comment: 17 pages, 23 figures, revised version with improved explanation of
the MCBR and overall wording. Accepted for publication in Astronomy and
Astrophysics (to appear in the Planck pre-launch special issue
Seasonal Variation of White Clover Morphology at the North of Buenos Aires Province, Argentine
In order to study the seasonal variation in morphological characters that contribute to forage production in white clover (Trifolium repens L.) cultivars, a trial was conducted at Pergamino Agricultural Experimental Station INTA located north of Buenos Aires province, Argentina. The experimental plots were set out in a completely randomized design with four replicates. Measurements were performed over eight seasons throughout two years. The used cultivars had been previously reported as having differences in seasonal productivity. Significant differences were detected among seasons for all measured characters i.e. stolon length, number of buds, branches and leaves, and leaf area. Differences among cultivars in almost all the season were only found for leaf area and stolon length. The growth in length of stolons kept a consistent pattern in both years. No cultivar produced vegetative buds during summers. The characters most affected by environmental stress were bud and branch development
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