12,679 research outputs found
Syllabus ECONOMIC RELATIONSHIP BETWEEN NONPROFIT AND PUBLIC SECTOR ORGANIZATIONS
Questo è il syllabus completo del corso: stampatelo e portatelo sempre a lezione! Al fine di evitare duplicazioni, evitate di stampare le pagine della Guida dello Studente. ENGLISH VERSION: This is the complete syllabus: print it and keept it always with you when you have classes! Do not print out the pages contained in the Student's guide to avoid redundancies
The discovery of high power - high synchrotron peak blazars
We study the quasi-simultaneous near-IR, optical, UV, and X-ray photometry of
eleven gamma-ray selected blazars for which redshift estimates larger than 1.2
have been recently provided. Four of these objects turn out to be high-power
blazars with the peak of their synchrotron emission between ~ 3 x 10^15 and ~
10^16 Hz, and therefore of a kind predicted to exist but never seen before.
This discovery has important implications for our understanding of physical
processes in blazars, including the so-called "blazar sequence", and might also
help constraining the extragalactic background light through gamma-ray
absorption since two sources are strongly detected even in the 10 - 100 GeV
Fermi-LAT band. Based on our previous work and their high powers, these sources
are very likely high-redshift flat-spectrum radio quasars with their emission
lines swamped by the non-thermal continuum.Comment: 5 pages, 6 colour figures, accepted for publication in the Monthly
Notices of the Royal Astronomical Societ
Characterization of the Community Structure of Large Scale Functional Brain Networks During Ketamine-Medetomidine Anesthetic Induction
One of the central questions in neuroscience is to understand the way
communication is organized in the brain, trying to comprehend how cognitive
capacities or physiological states of the organism are potentially related to
brain activities involving interactions of several brain areas. One important
characteristic of the functional brain networks is that they are modularly
structured, being this modular architecture regarded to account for a series of
properties and functional dynamics. In the neurobiological context, communities
may indicate brain regions that are involved in one same activity, representing
neural segregated processes. Several studies have demonstrated the modular
character of organization of brain activities. However, empirical evidences
regarding to its dynamics and relation to different levels of consciousness
have not been reported yet. Within this context, this research sought to
characterize the community structure of functional brain networks during an
anesthetic induction process. The experiment was based on intra-cranial
recordings of neural activities of an old world macaque of the species Macaca
fuscata during a Ketamine-Medetomidine anesthetic induction process. Networks
were serially estimated in time intervals of five seconds. Changes were
observed within about one and a half minutes after the administration of the
anesthetics, revealing the occurrence of a transition on the community
structure. The awake state was characterized by the presence of large clusters
involving frontal and parietal regions, while the anesthetized state by the
presence of communities in the primary visual and motor cortices, being the
areas of the secondary associative cortex most affected. The results report the
influence of general anesthesia on the structure of functional clusters,
contributing for understanding some new aspects of neural correlates of
consciousness.Comment: 24 pages, 8 figures. arXiv admin note: text overlap with
arXiv:1604.0000
Structure and Dynamics of Brain Lobes Functional Networks at the Onset of Anesthesia Induced Loss of Consciousness
Anesthetic agents are neurotropic drugs able to induce dramatic alterations
in the thalamo-cortical system, promoting a drastic reduction in awareness and
level of consciousness. There is experimental evidence that general anesthesia
impacts large scale functional networks leading to alterations in the brain
state. However, the way anesthetics affect the structure assumed by functional
connectivity in different brain regions have not been reported yet. Within this
context, the present study has sought to characterize the functional brain
networks respective to the frontal, parietal, temporal and occipital lobes. In
this experiment, electro-physiological neural activity was recorded through the
use of a dense ECoG-electrode array positioned directly over the cortical
surface of an old world monkey of the species Macaca fuscata. Networks were
serially estimated over time at each five seconds, while the animal model was
under controlled experimental conditions of an anesthetic induction process. In
each one of the four cortical brain lobes, prominent alterations on distinct
properties of the networks evidenced a transition in the networks architecture,
which occurred within about one and a half minutes after the administration of
the anesthetics. The characterization of functional brain networks performed in
this study represents important experimental evidence and brings new knowledge
towards the understanding of neural correlates of consciousness in terms of the
structure and properties of the functional brain networks.Comment: 41 pages; 30 figures; 30 tables. arXiv admin note: substantial text
overlap with arXiv:1604.0000
The Blazar Sequence: Validity and Predictions
The "blazar sequence" posits that the most powerful BL Lacertae objects and
flat-spectrum radio quasars should have relatively small synchrotron peak
frequencies, nu_peak, and that the least powerful such objects should have the
highest nu_peak values. This would have strong implications for our
understanding of jet formation and physics and the possible detection of
powerful, moderately high-redshift TeV blazars. I review the validity of the
blazar sequence by using the results of very recent surveys and compare its
detailed predictions against observational data. I find that the blazar
sequence in its simplest form is ruled out. However, powerful flat-spectrum
radio quasars appear not to reach the nu_peak typical of BL Lacs. This could
indeed be related to some sort of sequence, although it cannot be excluded that
it is instead due to a selection effect.Comment: 9 pages, 4 figures, invited talk at the Workshop "The Multi-messenger
approach to high energy gamma-ray sources", Barcelona, Spain, July 4-7, 2006,
to appear in the proceeding
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