421 research outputs found
A percolation system with extremely long range connections and node dilution
We study the very long-range bond-percolation problem on a linear chain with
both sites and bonds dilution. Very long range means that the probability
for a connection between two occupied sites at a distance
decays as a power law, i.e. when , and
when . Site dilution means that the occupancy probability of a site
is . The behavior of this model results from the competition
between long-range connectivity, which enhances the percolation, and site
dilution, which weakens percolation. The case with is
well-known, being the exactly solvable mean-field model. The percolation order
parameter is investigated numerically for different values of
, and . We show that in the ranges
and the percolation order parameter depends only on
the average connectivity of sites, which can be explicitly computed in
terms of the three parameters , and
Delocalization and wave-packet dynamics in one-dimensional diluted Anderson models
We study the nature of one-electron eigen-states in a one-dimensional diluted
Anderson model where every Anderson impurity is diluted by a periodic function
. Using renormalization group and transfer matrix techniques, we provide
accurate estimates of the extended states which appear in this model, whose
number depends on the symmetry of the diluting function . The density of
states (DOS) for this model is also numerically obtained and its main features
are related to the symmetries of the diluting function . Further, we show
that the emergence of extended states promotes a sub-diffusive spread of an
initially localized wave-packet.Comment: 6 pages, 6 figures, to appear in EPJ
Describing astronomy identity of upper primary and middle school students through structural equation modeling
We describe how young students situate themselves with respect to astronomy through an identity framework that features four dimensions: interest, utility value, confidence, and conceptual knowledge. Overall, about 900 Italian students, from 5th to 9th grade (9-14 years old), were involved in the study. We tested our model using confirmatory factor analysis and structural equation modeling. Differences between girls and boys and across school levels were also investigated. Results show that interest has both a direct and an indirect effect on astronomy identity. The indirect effect of interest on identity is mediated by utility value. Moreover, confidence mediates the effect of interest on conceptual knowledge. Concerning differences between girls and boys, we found that the effect of interest on identity is greater for girls than for boys and that the utility value mediates the effect of interest on identity for boys but not for girls. Finally, our findings show also that the students' interest in astronomy and confidence in their performance decrease with age, with a potential negative impact on conceptual knowledge and future career choice in astronomy. The astronomy identity framework can be employed to examine the role of affective variables on performance and persistence in astronomy and to improve the design of teaching-learning activities that can potentially stimulate a lasting interest in astronomy
Inherited causes of clonal haematopoiesis in 97,691 whole genomes
Age is the dominant risk factor for most chronic human diseases, but the mechanisms through which ageing confers this risk are largely unknown1. The age-related acquisition of somatic mutations that lead to clonal expansion in regenerating haematopoietic stem cell populations has recently been associated with both haematological cancer2,3,4 and coronary heart disease5—this phenomenon is termed clonal haematopoiesis of indeterminate potential (CHIP)6. Simultaneous analyses of germline and somatic whole-genome sequences provide the opportunity to identify root causes of CHIP. Here we analyse high-coverage whole-genome sequences from 97,691 participants of diverse ancestries in the National Heart, Lung, and Blood Institute Trans-omics for Precision Medicine (TOPMed) programme, and identify 4,229 individuals with CHIP. We identify associations with blood cell, lipid and inflammatory traits that are specific to different CHIP driver genes. Association of a genome-wide set of germline genetic variants enabled the identification of three genetic loci associated with CHIP status, including one locus at TET2 that was specific to individuals of African ancestry. In silico-informed in vitro evaluation of the TET2 germline locus enabled the identification of a causal variant that disrupts a TET2 distal enhancer, resulting in increased self-renewal of haematopoietic stem cells. Overall, we observe that germline genetic variation shapes haematopoietic stem cell function, leading to CHIP through mechanisms that are specific to clonal haematopoiesis as well as shared mechanisms that lead to somatic mutations across tissues
Il Nibbio reale Milvus milvus svernante in Italia, sintesi di cinque anni di monitoraggio
Beginning in December 2011, CISO has promoted a monitoring project for Red kite\u2019s wintering population in Italy. This paper shows the results of the first five survey seasons, ie from December 2011 to January 2016. The censuses, always done at sunset, covered the eleven Central-Southern regions for which winter roosts were already known. The number of actual kites censuses each winter varied between about 1500 and over 1700 individuals, with strong oscillations for single roosts. The population is mainly concentrated in Basilicata with more than 64% of the entire winter population. Interesting data were also been found in Lazio, Abruzzo and Molise, which altogether host about 25% of the national population. Encouraging data come from Tuscany where, following a reintroduction project, a wintering roost of about 80 units was found. Bad results are from censuses conducted in Campania, Calabria, Sicily and Sardinia, where the population seems to be greatly reduced
Il Nibbio reale Milvus milvus svernante in Italia, sintesi di cinque anni di monitoraggio
Beginning in December 2011, CISO has promoted a monitoring project for Red kite\u2019s wintering population in Italy. This paper shows the results of the first five survey seasons, ie from December 2011 to January 2016. The censuses, always done at sunset, covered the eleven Central-Southern regions for which winter roosts were already known. The number of actual kites censuses each winter varied between about 1500 and over 1700 individuals, with strong oscillations for single roosts. The population is mainly concentrated in Basilicata with more than 64% of the entire winter population. Interesting data were also been found in Lazio, Abruzzo and Molise, which altogether host about 25% of the national population. Encouraging data come from Tuscany where, following a reintroduction project, a wintering roost of about 80 units was found. Bad results are from censuses conducted in Campania, Calabria, Sicily and Sardinia, where the population seems to be greatly reduced
Black hole thermodynamical entropy
As early as 1902, Gibbs pointed out that systems whose partition function
diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs
(BG) theory. Consistently, since the pioneering Bekenstein-Hawking results,
physically meaningful evidence (e.g., the holographic principle) has
accumulated that the BG entropy of a black hole is
proportional to its area ( being a characteristic linear length), and
not to its volume . Similarly it exists the \emph{area law}, so named
because, for a wide class of strongly quantum-entangled -dimensional
systems, is proportional to if , and to if
, instead of being proportional to (). These results
violate the extensivity of the thermodynamical entropy of a -dimensional
system. This thermodynamical inconsistency disappears if we realize that the
thermodynamical entropy of such nonstandard systems is \emph{not} to be
identified with the BG {\it additive} entropy but with appropriately
generalized {\it nonadditive} entropies. Indeed, the celebrated usefulness of
the BG entropy is founded on hypothesis such as relatively weak probabilistic
correlations (and their connections to ergodicity, which by no means can be
assumed as a general rule of nature). Here we introduce a generalized entropy
which, for the Schwarzschild black hole and the area law, can solve the
thermodynamic puzzle.Comment: 7 pages, 2 figures. Accepted for publication in EPJ
The role of resveratrol on skeletal muscle cell differentiation and myotube hypertrophy during glucose restriction
Glucose restriction (GR) impairs muscle cell differentiation and evokes myotube atrophy. Resveratrol treatment in skeletal
muscle cells improves inflammatory-induced reductions in skeletal muscle cell differentiation. We therefore hypothesised
that resveratrol treatment would improve muscle cell differentiation and myotube hypertrophy in differentiating C2C12
myoblasts and mature myotubes during GR. Glucose restriction at 0.6 g/L (3.3 mM) blocked differentiation and myotube
hypertrophy versus high-glucose (4.5 g/L or 25 mM) differentiation media (DM) conditions universally used for myoblast
culture. Resveratrol (10 μM) treatment increased SIRT1 phosphorylation in DM conditions, yet did not improve differentiation
when administered to differentiating myoblasts in GR conditions. Resveratrol did evoke increases in hypertrophy of mature
myotubes under DM conditions with corresponding elevated Igf-I and Myhc7 gene expression, coding for the ‘slow’ type I
MYHC protein isoform. Inhibition of SIRT1 via EX-527 administration (100 nM) also reduced myotube diameter and area
in DM conditions and resulted in lower gene expression of Myhc 1, 2 and 4 coding for ‘intermediate’ and ‘faster’ IIx, IIa
and IIb protein isoforms, respectively. Resveratrol treatment did not appear to modulate phosphorylation of energy-sensing
protein AMPK or protein translation initiator P70S6K. Importantly, in mature myotubes, resveratrol treatment was able to
ameliorate reduced myotube growth in GR conditions over an acute 24-h period, but not over 48–72 h. Overall, resveratrol
evoked myotube hypertrophy in DM conditions while favouring ‘slower’ Myhc gene expression and acutely ameliorated
impaired myotube growth observed during glucose restriction
Efficient CRISPR/Cas9 genome editing in a salmonid fish cell line using a lentivirus delivery system
The present study was funded by were funded by the Biotechnology and Biological Sciences Research Council (BB/R008612/1, BB/S004343/1 to RH and RG; grant BB/R008973/1 to SM and CD) and the Institute Strategic Programme Grants (BBS/E/D/20002172, BBS/E/D/30002275 and BBS/E/D/10002070, to RH and RG). The funders had no roles in the study design, data collection and analysis, decision to publish or preparation of the manuscript.Peer reviewedPublisher PD
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