278 research outputs found
Astrophysical constraints on non-standard coherent neutrino-nucleus scattering
The exciting possibility of detecting supernova, solar, and atmospheric
neutrinos with coherent neutrino-nucleus scattering detectors is within reach,
opening up new avenues to probe New Physics. We explore the possibility of
constraining non-standard coherent neutrino-nucleus scattering through
astrophysical neutrinos. Sensitivity bounds on the mass and coupling of the new
mediator are obtained by inspecting the modifications induced by the new
interaction on the recoil rate observable in the upcoming RES-NOVA and DARWIN
facilities. Under the assumption of optimal background tagging, the detection
of neutrinos from a galactic supernova burst, or one-year exposure to solar and
atmospheric neutrinos, will place the most stringent bounds for mediator
couplings and mediator masses between 1 and 100 MeV. A
similar, but slightly improved, potential to COHERENT will be provided for
larger mediator masses. In particular, RES-NOVA and DARWIN may potentially
provide one order of magnitude tighter constraints than XENON1T on the mediator
coupling. Non-standard coherent neutrino-nucleus scattering may also force
neutrinos to be trapped in the supernova core; this argument allows to probe
the region of the parameter space with , which is currently
excluded by other coherent neutrino-nucleus scattering facilities or other
astrophysical and terrestrial constraints.Comment: 20 pages, 12 figures. Discussion on the forecasted bounds extended,
conclusions unchanged. Matches version accepted in Phys. Rev.
Blended learning and emergency distance learning. How to rethink learning environments at school
The Italian School context, in the current scenario, represent a field in which emerges many innovation possibilities. The activation of emergency distance learning due to the suspension of presence teaching activities, represents the occasion for Italian School to renovate school traditional dynamics. Aware of the fact that virtual learning environments provide different teaching and learning dynamics, it is important to reform learning design practices and organize an integrated learning environment that eases effective learning paths. In this paper we present the design of a research-training-action path in a Secondary Italian School in which it will be activated a training course for teachers and introduced the e-learning platform Moodle in teaching-learning activities
Measuring the supernova unknowns at the next-generation neutrino telescopes through the diffuse neutrino background
The detection of the diffuse supernova neutrino background (DSNB) will
preciously contribute to gauge the properties of the core-collapse supernova
population. We estimate the DSNB event rate in the next-generation neutrino
detectors, Hyper-Kamiokande enriched with Gadolinium, JUNO, and DUNE. The
determination of the supernova unknowns through the DSNB will be heavily driven
by Hyper-Kamiokande, given its higher expected event rate, and complemented by
DUNE that will help in reducing the parameters uncertainties. Meanwhile, JUNO
will be sensitive to the DSNB signal over the largest energy range. A joint
statistical analysis of the expected rates in 20 years of data taking from the
above detectors suggests that we will be sensitive to the local supernova rate
at most at a 20-33% level. A non-zero fraction of supernovae forming black
holes will be confirmed at a 90% CL, if the true value of that fraction is
larger than 20%. On the other hand, the DSNB events show extremely poor
statistical sensitivity to the nuclear equation of state and mass accretion
rate of the progenitors forming black holes.Comment: 29 pages, including 15 figures. Minor changes in the text, matches
version accepted for publication in JCA
Evaluation of experimental wines obtained from “new-old” white-berry genotypes of the northern province of the Apulia region (Daunia, Italy)
EVALUATION OF EXPERIMENTAL WINES OBTAINED FROM “NEW OLD” WHITE-BERRY GENOTYPES OF THE NORTHERN PROVINCE OF THE APULIA REGION (DAUNIA, ITALY)
Non-Universal Stellar Initial Mass Functions: Large Uncertainties in Star Formation Rates at and Other Astrophysical Probes
We explore the assumption, widely used in many astrophysical calculations,
that the stellar initial mass function (IMF) is universal across all galaxies.
By considering both a canonical Salpeter-like IMF and a non-universal IMF, we
are able to compare the effect of different IMFs on multiple observables and
derived quantities in astrophysics. Specifically, we consider a non-universal
IMF which varies as a function of the local star formation rate, and explore
the effects on the star formation rate density (SFRD), the extragalactic
background light, the supernova (both core-collapse and thermonuclear) rates,
and the diffuse supernova neutrino background. Our most interesting result is
that our adopted varying IMF leads to much greater uncertainty on the SFRD at
than is usually assumed. Indeed, we find a SFRD (inferred using
observed galaxy luminosity distributions) that is a factor of lower
than canonical results obtained using a universal Salpeter-like IMF. Secondly,
the non-universal IMF we explore implies a reduction in the supernova
core-collapse rate of a factor of , compared against a universal IMF.
The other potential tracers are only slightly affected by changes to the
properties of the IMF. We find that currently available data do not provide a
clear preference for universal or non-universal IMF. However, improvements to
measurements of the star formation rate and core-collapse supernova rate at
redshifts may offer the best prospects for discernment.Comment: 15 pages, 11 figures, 1 appendi
Spontaneous emission control of colloidal nanocrystals using nanoimprinted photonic crystals
The authors report on the fabrication and optical characterizations of two-dimensional photonic crystals fabricated by nanoimprint lithography in a nanocomposite polymer incorporating highly luminescent and red emitting (CdSe)ZnS core-shell colloidal nanocrystals. Photonic crystal structures enhance the light emitted from the quantum sized nanoparticles in the composite layer by slowing the propagation speed of the photons, thus increasing the coupling to the out-of-plane radiative modes. A 200% enhancement of the light collection is achieved compared to an unpatterned sample. (c) 2007 American Institute of Physics. (DOI:10.1063/1.2430625
Oxidation of Hepatic Carnitine Palmitoyl Transferase-I (CPT-I) Impairs Fatty Acid Beta-Oxidation in Rats Fed a Methionine-Choline Deficient Diet
There is growing evidence that mitochondrial dysfunction, and more specifically fatty acid β-oxidation impairment, is involved in the pathophysiology of non-alcoholic steatohepatitis (NASH). The goal of the present study was to achieve more understanding on the modification/s of carnitinepalmitoyltransferase-I (CPT-I), the rate-limiting enzyme of the mitochondrial fatty acid β-oxidation, during steatohepatitis. A high fat/methionine-choline deficient (MCD) diet, administered for 4 weeks, was used to induce NASH in rats. We demonstrated that CPT-Iactivity decreased, to the same extent, both in isolated liver mitochondria and in digitonin-permeabilized hepatocytes from MCD-diet fed rats. At the same time, the rate of total fatty acid oxidation to CO2 and ketone bodies, measured in isolated hepatocytes, was significantly lowered in treated animals when compared to controls. Finally, an increase in CPT-I mRNA abundance and protein content, together with a high level of CPT-I protein oxidation was observed in treated rats. A posttranslational modification of rat CPT-I during steatohepatitis has been here discussed
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