6,267 research outputs found
Reaction mechanisms involved in the production of neutron-rich isotopes
The reaction mechanisms best suited for the production of neutron-rich
nuclei, fragmentation and fission, are discussed. Measurements of the
production cross sections of reaction residues together with model calculations
allow to conclude about the expected production rates of neutron-rich isotopes
in future facilities.Comment: 9 pages, 8 figures Proceedings of the Third International Conference
on Fission and Properties of Neutron-Rich Nuclei November 3-9, 2002, Sanibel
Island, Florida, US
Dispersion of longitudinal momentum distributions induced in fragmentation reactions
On the basis of systematic measurements of fragmentation reactions, which
provide a detailed overview on the velocity distributions of residual nuclei,
an improved description of the kinematical properties of the fragmentation
residues is established. This work is dedicated to the fluctuations of their
momentum distributions. In contrast to previous investigations, limited to
close-to-projectile fragments, we extended our study to the entire production
range, down to the lightest observed fragments. In this context, beside the
contribution of abrasion and evaporation processes, we considered the effect of
the thermal break-up on the width of the momentum distributions. Using
approximated theoretical descriptions of the different reaction stages, a new
analytical formula for the variance of the momentum distribution is derived,
which is well adapted to technical applications.Comment: 14 pages, 3 figures, background info. at
http://www-wnt.gsi.de/charms
Experimental Indications for the Response of the Spectators to the Participant Blast
Precise momentum distributions of identified projectile fragments, formed in
the reactions 238U + Pb and 238U + Ti at 1 A GeV, are measured with a
high-resolution magnetic spectrometer. With increasing mass loss, the
velocities first decrease as expected from previously established systematics,
then level off, and finally increase again. Light fragments are on the average
even faster than the projectiles. This finding is interpreted as the response
of the spectators to the participant blast. The re-acceleration of projectile
spectators is sensitive to the nuclear mean field and provides a new tool for
investigating the equation of state of nuclear matter.Comment: 7 pages, 3 figures, background information on
http://www-wnt.gsi.de/kschmidt
Biological aspects of mTOR in leukemia
The mammalian target of rapamycin (mTOR) is a central processor of intra-and extracellular signals, regulating many fundamental cellular processes such as metabolism, growth, proliferation, and survival. Strong evidences have indicated that mTOR dysregulation is deeply implicated in leukemogenesis. This has led to growing interest in the development of modulators of its activity for leukemia treatment. This review intends to provide an outline of the principal biological and molecular functions of mTOR. We summarize the current understanding of how mTOR interacts with microRNAs, with components of cell metabolism, and with controllers of apoptotic machinery. Lastly, from a clinical/translational perspective, we recapitulate the therapeutic results in leukemia, obtained by using mTOR inhibitors as single agents and in combination with other compounds
Occupational risk factors in inflammatory bowel disease
Crohn's disease and ulcerative colitis are the two main forms of inflammatory bowel disease (IBD). Although the aetiology of IBD is not completely understood, an interaction between genetic and environmental factors has been proposed. In this context, however, environmental epidemiology lacks a comprehensive evaluation of the possible role of occupational exposures in IBD development and progression. Therefore, aim of our review was to evaluate how certain occupational risk factors may affect IBD pathogenesis, clinical history and severity of disease manifestations
Misure gravimetriche a L’Aquila. Confronto con i valori rilevati nel 1995
Nel febbraio 2010 si è dato inizio alla
realizzazione di una rete gravimetrica a
L’Aquila con l’istituzione di una
stazione assoluta. La stazione è stata
realizzata nel Palazzo Comunale della
città di L’Aquila (Palazzo Margherita
– foto a), nel centro della città , in un
locale al piano terra (foto b). Sono
state effettuata anche misure
gravimetriche relative al fine di
misurare il locale gradiente verticale
della gravitĂ (foto c) e riportare il
valore assoluto ad una stazione
satellite esterna all’edificio (foto d).
Nel corso della campagna è stato anche
effettuato il collegamento gravimetrico
tra la nuova stazione e quella istituita
nel 1995 nei laboratori sotterranei dei
Laboratori Nazionali del Gran Sasso
(LNGS) (foto e) dove è stato anche
misurato il gradiente verticale. Tale
punto fu allora istituito quale nodo
fondamentale della costituenda “Rete
Gravimetrica Nazionale di Ordine
Zero”
System dynamics modeling as a circular process: The smart commons approach to impact management
Thirty years of precise gravity measurements at Mt. Vesuvius: an approach to detect underground mass movements
Since 1982, high precision gravity measurements have been routinely carried
out on Mt. Vesuvius. The gravity network consists of selected sites
most of them coinciding with, or very close to, leveling benchmarks to remove
the effect of the elevation changes from gravity variations. The reference
station is located in Napoli, outside the volcanic area. Since 1986,
absolute gravity measurements have been periodically made on a station
on Mt. Vesuvius, close to a permanent gravity station established in 1987,
and at the reference in Napoli. The results of the gravity measurements
since 1982 are presented and discussed. Moderate gravity changes on
short-time were generally observed. On long-term significant gravity
changes occurred and the overall fields displayed well defined patterns.
Several periods of evolution may be recognized. Gravity changes revealed
by the relative surveys have been confirmed by repeated absolute measurements,
which also confirmed the long-term stability of the reference
site. The gravity changes over the recognized periods appear correlated
with the seismic crises and with changes of the tidal parameters obtained
by continuous measurements. The absence of significant ground deformation
implies masses redistribution, essentially density changes without
significant volume changes, such as fluids migration at the depth of
the seismic foci, i.e. at a few kilometers. The fluid migration may occur
through pre-existing geological structures, as also suggested by hydrological
studies, and/or through new fractures generated by seismic activity.
This interpretation is supported by the analyses of the spatial gravity
changes overlapping the most significant and recent seismic crises
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