5,659 research outputs found
Primordial Nucleosynthesis: from precision cosmology to fundamental physics
We present an up-to-date review of Big Bang Nucleosynthesis (BBN). We discuss
the main improvements which have been achieved in the past two decades on the
overall theoretical framework, summarize the impact of new experimental results
on nuclear reaction rates, and critically re-examine the astrophysical
determinations of light nuclei abundances. We report then on how BBN can be
used as a powerful test of new physics, constraining a wide range of ideas and
theoretical models of fundamental interactions beyond the standard model of
strong and electroweak forces and Einstein's general relativity.Comment: 148 pages, 66 figures, revised version accepted by Physics Report
High Energy Neutrinos with a Mediterranean Neutrino Telescope
The high energy neutrino detection by a km^3 Neutrino Telescope placed in the
Mediterranean sea provides a unique tool to both determine the diffuse
astrophysical neutrino flux and the neutrino-nucleon cross section in the
extreme kinematical region, which could unveil the presence of new physics.
Here is performed a brief analysis of possible NEMO site performances.Comment: 4 pages, 3 figures, Proceedings of the 30th ICRC 200
Disentangling neutrino-nucleon cross section and high energy neutrino flux with a km^3 neutrino telescope
The energy--zenith angular event distribution in a neutrino telescope
provides a unique tool to determine at the same time the neutrino-nucleon cross
section at extreme kinematical regions, and the high energy neutrino flux. By
using a simple parametrization for fluxes and cross sections, we present a
sensitivity analysis for the case of a km^3 neutrino telescope. In particular,
we consider the specific case of an under-water Mediterranean telescope placed
at the NEMO site, although most of our results also apply to an under-ice
detector such as IceCube. We determine the sensitivity to departures from
standard values of the cross sections above 1 PeV which can be probed
independently from an a-priori knowledge of the normalization and energy
dependence of the flux. We also stress that the capability to tag downgoing
neutrino showers in the PeV range against the cosmic ray induced background of
penetrating muons appears to be a crucial requirement to derive meaningful
constraints on the cross section.Comment: 10 pages, 28 figure
A paradigmatic autistic phenotype associated with loss of PCDH11Y and NLGN4Y genes
Background: Most studies relative to Y chromosome abnormalities are focused on the sexual developmental disorders. Recently, a few studies suggest that some genes located on Y chromosome may be related to different neurodevelopment disorders. Case presentation: We report a child with sexual developmental disorder associated with a peculiar phenotype characterized by severe language impairment and autistic behaviour associated with a mosaicism [45,X(11)/46,XY(89)] and a partial deletion of the short and long arm of Y chromosome (del Yp11.31q11.23) that also involves the loss of both PCDH11Y and NLGN4Y genes. To our knowledge no study has ever reported the occurrence of the lack of both PCDH11Y and NLGN4Y located in the Y chromosome in the same patient. Conclusions: We hypothesized a functional complementary role of PCDH11Y and NLGN4Y within formation/maturation of the cerebral cortex. The impairment of early language development may be mainly related to the lack of PCDH11Y that underlies the early language network development and the later appearance of the autistic behaviour may be mainly related to deficit of inhibitory glicinergic neurotransmission NLGN4Y-linked
Using BBN in cosmological parameter extraction from CMB: a forecast for Planck
Data from future high-precision Cosmic Microwave Background (CMB)
measurements will be sensitive to the primordial Helium abundance . At the
same time, this parameter can be predicted from Big Bang Nucleosynthesis (BBN)
as a function of the baryon and radiation densities, as well as a neutrino
chemical potential. We suggest to use this information to impose a
self-consistent BBN prior on and determine its impact on parameter
inference from simulated Planck data. We find that this approach can
significantly improve bounds on cosmological parameters compared to an analysis
which treats as a free parameter, if the neutrino chemical potential is
taken to vanish. We demonstrate that fixing the Helium fraction to an arbitrary
value can seriously bias parameter estimates. Under the assumption of
degenerate BBN (i.e., letting the neutrino chemical potential vary), the
BBN prior's constraining power is somewhat weakened, but nevertheless allows us
to constrain with an accuracy that rivals bounds inferred from present
data on light element abundances.Comment: 14 pages, 4 figures; v2: minor changes, matches published versio
Analisi spettrale parametrica e di polarizzazione applicate agli eventi sismici registrati sul vulcano sottomarino Marsili
Nel luglio 2006, nell’ambito della campagna di ricerche PRO.ME.TH.E.US (PROgram of Mediterranean
Exploration for THermal Energy Use), l’OBS Lab dell’Osservatorio Geofisico di Gibilmanna dell’INGVCNT,
ha deposto un prototipo di OBS/H sulla sommità del vulcano sottomarino Marsili (39° 16,383’ lat.
Nord, 14° 23,588’ long. Est.) alla profondità di 790 m (D’Anna et alii, 2007); lo strumento ha registrato
l’attività sismica del vulcano dal 12 al 21 luglio 2006. L’OBS/H era equipaggiato con un sismometro
Trillium 40s della Nanometrics e un idrofono OAS E-2PD. La digitalizzazione è stata effettuata da un
convertitore A/D a 21 bit a quattro canali (SEND Geolon MLS) e i segnali sono stati campionati ad una
frequenza di 200 c/s (D’Anna et alii, 2007).In una prima fase di studio D’Alessandro et alii (2006) hanno individuato, nel segnale acquisito, la
presenza di una elevata attività sismica (oltre 1000 eventi registrati in 9 giorni) legata probabilmente
all’attività del vulcano Marsili oltre a eventi tettonici e forme d’onda transitorie di origine non sismica. In
base ad analisi spettrali non parametriche, l’attività registrata era stata suddivisa in: eventi noti in
letteratura come VT-B (Volcanic-Tectonic event, type B) che si manifestano in sciami, eventi ad alta frequenza legati a probabile attività idrotermale ed eventi classificabili come “Tornillo” o LPE (Long-
Period Event) probabilmente generati da fenomeni di risonanza legati ad attività magmatica (Chouet,
1996).
Al fine di caratterizzare con idonei parametri quantitativi i segnali appartenenti ai gruppi individuati e fare
delle ipotesi sui diversi meccanismi sorgente, sono state successivamente eseguite analisi spettrali
parametriche e di polarizzazione, che sono oggetto di questo lavoro.
Rispetto all’analisi di Fourier, l’analisi spettrale parametrica permette di ottenere una migliore risoluzione,
quando il segnale da analizzare presenta breve durata. Noi abbiamo applicato tale tipo di analisi agli eventi
classificabili come Tornillo. Tali eventi sono generalmente quasi-monocromatici e presentano un inizio di
tipo impulsivo, seguito da un lento e graduale decadimento in ampiezza. La descrizione delle frequenze di
oscillazione di un Tornillo è di fondamentale importanza per stimare le caratteristiche della sorgente. Un
metodo ad alta risoluzione spettrale basato sulle proprietà di un sistema dinamico è stato sviluppato da
Kumazawa et alii (1990). Questo metodo chiamato Sompi è stato successivamente esteso da Yokoyama et
alii (1997) alle equazioni AR non omogenee. Noi abbiamo utilizzato quest’ultimo metodo, implementando
la procedura di Nakano et alii (1998), per analizzare i Tornillo ed attribuirgli una frequenza complessa.L’analisi di polarizzazione, risolvendo il problema agli autovalori associato alla matrice di covarianza dei
segnali relativi alle tre componenti del moto, permette di definire l’orientazione e la lunghezza degli assi
dell’ellissoide di polarizzazione associato alla finestra temporale del segnale sismico presa in esame. Al
fine di migliorare la stima degli attributi di polarizzazione, la matrice di covarianza è stata corretta per la
presenza di rumore sismico, sotto l’ipotesi di stocasticità e stazionarietà del rumore stesso. L’analisi di
polarizzazione è stata applicata a oltre 200, tra gli eventi VT-B con maggiore energia, per individuare attraverso la direzione di polarizzazione delle fasi P (linearmente polarizzate) eventuali direzioni
prevalenti di provenienza e quindi l’esistenza e ubicazione di volumi sismogenetici
Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample
We test the gamma-ray burst correlation between temporal variability and peak
luminosity of the -ray profile on a homogeneous sample of 36 Swift/BAT
GRBs with firm redshift determination. This is the first time that this
correlation can be tested on a homogeneous data sample. The correlation is
confirmed, as long as the 6 GRBs with low luminosity (<5x10^{50} erg s^{-1} in
the rest-frame 100-1000 keV energy band) are ignored. We confirm that the
considerable scatter of the correlation already known is not due to the
combination of data from different instruments with different energy bands, but
it is intrinsic to the correlation itself. Thanks to the unprecedented
sensitivity of Swift/BAT, the variability/peak luminosity correlation is tested
on low-luminosity GRBs. Our results show that these GRBs are definite outliers.Comment: Accepted for Publication in MNRAS. 10 pages, 5 figures, 3 table
Commonalities and distinctions between two neurodevelopmental disorder subtypes associated with SCN2A and SCN8A variants and literature review
This study was aimed to analyze the commonalities and distinctions of voltage-gated sodium channels, Nav1.2, Nav1.6, in neurodevelopmental disorders. An observational study was performed including two patients with neurodevelopmental disorders. The demographic, electroclinical, genetic, and neuropsychological characteristics were analyzed and compared with each other and then with the subjects carrying the same genetic variants reported in the literature. The clinical features of one of them argued for autism spectrum disorder and developmental delay, the other for intellectual disability, diagnoses confirmed by the neuropsychological assessment. The first patient was a carrier of SCN2A (p.R379H) variant while the second was carrier of SCN8A (p.E936K) variant, both involving the pore loop of the two channels. The results of this study suggest that the neurodevelopmental disorders without overt epilepsy of both patients can be the consequences of loss of function of Nav1.2/Nav1.6 channels. Notably, the SCN2A variant, with an earlier expression timing in brain development, resulted in a more severe phenotype as autism spectrum disorder and developmental delay, while the SCN8A variant, with a later expression timing, resulted in a less severe phenotype as intellectual disability
Cancer‐Related Cachexia: The Vicious Circle between Inflammatory Cytokines, Skeletal Muscle, Lipid Metabolism and the Possible Role of Physical Training
Cachexia is a multifactorial and multi‐organ syndrome that is a major cause of morbidity and mortality in late‐stage chronic diseases. The main clinical features of cancer‐related cachexia are chronic inflammation, wasting of skeletal muscle and adipose tissue, insulin resistance, anorexia, and impaired myogenesis. A multimodal treatment has been suggested to approach the multifactorial genesis of cachexia. In this context, physical exercise has been found to have a general effect on maintaining homeostasis in a healthy life, involving multiple organs and their metabolism. The purpose of this review is to present the evidence for the relationship between inflammatory cytokines, skeletal muscle, and fat metabolism and the potential role of exercise training in breaking the vicious circle of this impaired tissue cross‐talk. Due to the wide‐ranging effects of exercise training, from the body to the behavior and cognition of the individual, it seems to be able to improve the quality of life in this syndrome. Therefore, studying the molecular effects of physical exercise could provide important information about the interactions between organs and the systemic mediators involved in the overall homeostasis of the body
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