5,638 research outputs found
Mechanisms of vascular damage in SSc—implications for vascular treatment strategies
Vascular abnormalities are a major component of SSc, but little is known about the events or mechanisms that initiate vascular injury and prevent its repair. In SSc, angiogenesis is incomplete or lacking despite the increased expression of a large array of pro-angiogenic factors such as VEGF. Conflicting results have recently been published concerning the presence and role of vasculogenesis and circulating endothelial progenitor cells in SSc. It remains to be established if these endothelial progenitor cells are a marker of endothelial disease or a cause of insufficient vascular repair. Human mesenchymal stem cells (MSCs) may be an alternative source for endothelial progenitor cells, and it has been observed that the angiogenic potential of endothelial-like MSCs is reduced. Other mechanisms of vascular damage include oxidative stress and factors released from activated platelets. In addition, growth factors such as ET-1 and PDGF induce proliferation of vascular smooth muscle cells resulting in intimal thickening. For the development of new therapeutic strategies, it is important to realize that the different vascular pathologies—uncompensated loss of capillaries on one hand and vascular remodelling with a proliferative vasculopathy on the other—might require different treatment approache
Low emittance muon accelerator studies with production from positrons on target
A new scheme to produce very low emittance muon beams using a positron beam
of about 45~GeV interacting on electrons on target is presented.
One of the innovative topics to be investigated is the behaviour of the
positron beam stored in a low emittance ring with a thin target, that is
directly inserted in the ring chamber to produce muons. Muons can be
immediately collected at the exit of the target and transported to two
and accumulator rings and then accelerated and injected in muon
collider rings. We focus in this paper on the simulation of the e beam
interacting with the target, the effect of the target on the 6-D phase space
and the optimization of the e ring design to maximize the energy
acceptance. We will investigate the performance of this scheme, ring plus
target system, comparing different multi-turn simulations. The source is
considered for use in a multi-TeV collider in ref.[1]Comment: accepted for publication in Physical Review Accelerators and Beam
Vasculogenesis and angiogenesis: vascular damage in systemic sclerosis
La sclerosi sistemica (SSc) è una malattia multisistemica del connettivo caratterizzata dalla presenza di alterazioni microvascolari con deficit angiogenetico (1). Suddividendo la patogenesi della SSc in momenti successivi è possibile considerare il microcircolo come la struttura colpita dalla malattia che in più fasi coinvolge l’organismo del paziente affetto da SSc (2). La cellula endoteliale (CE) viene inizialmente attivata tramite una noxa ignota alla produzione di molecole di adesione, chemiochine, citochine e fattori di crescita. In tal modo viene facilitato il passaggio (homing) linfocitario nei tessuti. Inizialmente si ha un danno a carico della CE seguito da un ispessimento dell’intima e da un progressivo restringimento del lume fino alla completa ostruzione del vaso..
Da\phi ne gamma-rays factory
Gamma sources with high flux and spectral densities are the main requirements
for new nuclear physics experiments to be performed in several worldwide
laboratories and envisaged in the ELI-NP (Extreme Light Infrastructure-Nuclear
Physics) project or in the IRIDE (Interdisciplinary Research Infrastructure
with Dual Electron Linacs) proposals. The paper is focalized on an experiment
of gamma photons production using Compton collisions between the DA\Phi NE
electron beam and a high average power laser pulse, amplified in a
Fabry-P\'erot optical resonator. The calculations show that the resulting gamma
beam source has extremely interesting properties in terms of spectral density,
energy spread and gamma flux comparable (and even better) with the last
generation gamma sources. The energy of the gamma beam depends on the adopted
laser wavelength and can be tuned changing the energy of the electron ring. In
particular we have analyzed the case of a gamma factory tunable in the 2-9 MeV
range. The main parameters of this new facility are presented and the
perturbation on the transverse and longitudinal electron beam dynamics is
discussed. A preliminary accelerator layout to allow experiments with the gamma
beam is presented with a first design of the accelerator optics.Comment: 26 pages, 15 figure
Proposal of an experimental test at DAΦNE for the low emittance muon beam production from positrons on target
We present in this paper the proposal of an experimental test at DAΦNE of the positronring-plus-target scheme foreseen in the Low EMittance Muon Accelerator. This test would be a validation of the on-going studies for LEMMA and it would be synergic with other proposals at DAΦNE after the SIDDHARTA run. We discuss the beam dynamics studies for different targets inserted in a proper location through the ring, i.e. where the beam is focused and dispersion-free. Optimization of beam parameters, thickness and material of target and optics of the target insertion are shown as well. The development of the existent diagnostic needed to test the behavior of the circulating beam is described together with the turn-by-turn measurement systems of charge, lifetime and transverse size. Measurements on the temperature and thermo-mechanical stress on the target are also under study
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