1,364 research outputs found
Blazar Flaring Patterns (B-FlaP): Classifying Blazar Candidates of Uncertain type in the third Fermi-LAT catalog by Artificial Neural Networks
The Fermi Large Area Telescope (LAT) is currently the most important facility
for investigating the GeV -ray sky. With Fermi LAT more than three
thousand -ray sources have been discovered so far. 1144 () of
the sources are active galaxies of the blazar class, and 573 () are
listed as Blazar Candidate of Uncertain type (BCU), or sources without a
conclusive classification. We use the Empirical Cumulative Distribution
Functions (ECDF) and the Artificial Neural Networks (ANN) for a fast method of
screening and classification for BCUs based on data collected at -ray
energies only, when rigorous multiwavelength analysis is not available. Based
on our method, we classify 342 BCUs as BL Lacs and 154 as FSRQs, while 77
objects remain uncertain. Moreover, radio analysis and direct observations in
ground-based optical observatories are used as counterparts to the statistical
classifications to validate the method. This approach is of interest because of
the increasing number of unclassified sources in Fermi catalogs and because
blazars and in particular their subclass High Synchrotron Peak (HSP) objects
are the main targets of atmospheric Cherenkov telescopes.Comment: 18 pages, 17 figures, accepted for publication on MNRA
Chamber basis of the Orlik-Solomon algebra and Aomoto complex
We introduce a basis of the Orlik-Solomon algebra labeled by chambers, so
called chamber basis. We consider structure constants of the Orlik-Solomon
algebra with respect to the chamber basis and prove that these structure
constants recover D. Cohen's minimal complex from the Aomoto complex.Comment: 16 page
The Hilbert space operator formalism within dynamical reduction models
Unlike standard quantum mechanics, dynamical reduction models assign no
particular a priori status to `measurement processes', `apparata', and
`observables', nor self-adjoint operators and positive operator valued measures
enter the postulates defining these models. In this paper, we show why and how
the Hilbert-space operator formalism, which standard quantum mechanics
postulates, can be derived from the fundamental evolution equation of dynamical
reduction models. Far from having any special ontological meaning, we show that
within the dynamical reduction context the operator formalism is just a compact
and convenient way to express the statistical properties of the outcomes of
experiments.Comment: 25 pages, RevTeX. Changes made and two figures adde
Sub-lethal 5-fluorouracil dose challenges planarian stem cells promoting transcriptional profile changes in the pluripotent sigma-class neoblasts
Under physiological conditions, the complex planarian neoblast system is a composite of hierarchically organized stem cell sub-populations with sigma-class neoblasts, including clonogenic neoblasts, endowed with larger self-renewal and differentiation capabilities, thus generating all the other sub-populations and dominating the regenerative process. This complex system responds to differentiated tissue demands, ensuring a continuous cell turnover in a way to replace aged specialized cells and maintain tissue functionality. Potency of the neoblast system can be appreciated under challenging conditions in which these stem cells are massively depleted and the few remaining repopulate the entire body, ensuring animal resilience. These challenging conditions offer the possibility to deepen the relationships among different neoblast sub-populations, allowing to expose uncanonical properties that are negligible under physiological conditions. In this paper, we employ short, sub-lethal 5-fluorouracil treatment to specifically affect proliferating cells passing through the S phase and demonstrate that S-phase slowdown triggers a shift in the transcriptional profile of sigma neoblasts, which reduces the expression of their hallmark sox-P1. Later, some cells reactivate sox-P1 expression, suggesting that some neoblasts in the earlier steps of commitment could modulate their expression profile, reacquiring a wider differentiative potential
Thesaurus: un database per il patrimonio culturale sommerso
Thesaurus Project aims at promoting the knowledge of the underwater cultural heritage, ancient and modern, through the application of several typologies of tools: underwater autonomous vehicles, which will be able to explore the sea bottom in teams communicating with each other; a database, which will be useful to store and manage all the information referring to archaeological or historical objects, shipwrecks and sites. This paper aims to explain the logic structure of the database indicating the particular needs of the research, the different typologies of items which have to be managed (archaeological and historical objects; ancient, medieval or modern shipwrecks; underwater sites; written or figurative sources, etc.), the relation with other similar databases and projects. The main task of this part of Thesaurus is to plan and organize an IT system, which will allow archaeologists to describe information in detail, in order to make an efficient managing and retrieving data system available
Discovery of periodic dips in the brightest hard X-ray source of M31 with EXTraS
We performed a search for eclipsing and dipping sources in the archive of the
EXTraS project - a systematic characterization of the temporal behaviour of
XMM-Newton point sources. We discovered dips in the X-ray light curve of 3XMM
J004232.1+411314, which has been recently associated with the hard X-ray source
dominating the emission of M31. A systematic analysis of XMM-Newton
observations revealed 13 dips in 40 observations (total exposure time 0.8
Ms). Among them, four observations show two dips, separated by 4.01 hr.
Dip depths and durations are variable. The dips occur only during
low-luminosity states (L erg s), while the
source reaches L erg s. We propose this
system to be a new dipping Low-Mass X-ray Binary in M31 seen at high
inclination (60-80), the observed dipping periodicity is
the orbital period of the system. A blue HST source within the Chandra error
circle is the most likely optical counterpart of the accretion disk. The high
luminosity of the system makes it the most luminous dipper known to date.Comment: 11 pages, 2 figures, 5 tables, accepted for publication in ApJ
Relative influence of the adeno-associated virus (AAV) type 2 p5 element for recombinant AAV vector site-specific integration.
The p5 promoter region of the adeno-associated virus type 2 (AAV-2) rep gene has been described as essential for Rep-mediated site-specific integration (RMSSI) of plasmid sequences in human chromosome 19. We report here that insertion of a full-length or minimal p5 element between the viral inverted terminal repeats does not significantly increase RMSSI of a recombinant AAV (rAAV) vector after infection of growth-arrested or proliferating human cells. This result suggests that the p5 element may not improve RMSSI of rAAV vectors in vivo
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