1,853 research outputs found
Radiation Hardness tests with neutron flux on different Silicon photomultiplier devices
Radiation hardness is an important requirement for solid state readout
devices operating in high radiation environments common in particle physics
experiments. The MEGII experiment, at PSI, Switzerland, investigates the
forbidden decay . Exploiting the most intense
muon beam of the world. A significant flux of non-thermal neutrons (kinetic
energy ) is present in the experimental hall produced along
the beamline and in the hall itself. We present the effects of neutron fluxes
comparable to the MEGII expected doses on several Silicon PhotoMulitpliers
(SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEGII
experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and
Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical
Multiplication complex (SM1) moderated with water, located at the University of
Pavia (Italy). We report the change of SiPMs most important electric
parameters: dark current, dark pulse frequency, gain, direct bias resistance,
as a function of the integrated neutron fluency.Comment: 9 pages, 6 figures. Proceedings from Instrumentation for colliding
Beam Physics (INSTR-17) 27-02-2017/03-03-2017 Novosibirsk (R
Noncommutative Black Holes and the Singularity Problem
A phase-space noncommutativity in the context of a Kantowski-Sachs
cosmological model is considered to study the interior of a Schwarzschild black
hole. Due to the divergence of the probability of finding the black hole at the
singularity from a canonical noncommutativity, one considers a non-canonical
noncommutativity. It is shown that this more involved type of noncommutativity
removes the problem of the singularity in a Schwarzschild black hole.Comment: Based on a talk by CB at ERE2010, Granada, Spain, 6th-10th September
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Interpreting Rock-Cut Grave Cemeteries: the early medieval necropolis and enclosure of São Gens, Portugal
EXCAVATION AT SÃO GENS (Guarda district) in central Portugal has revealed an early medieval rock-cut grave cemetery and settlement, along with Roman and prehistoric evidence. The site presents an exceptionally rich palimpsest of archaeological monuments. This paper reviews the findings and seeks to address the problem of interpreting rock-cut grave cemeteries, by describing a spatial analytical methodology that draws on comparisons with early medieval cemeteries in England, as a means of enhancing the information deficit of such necropolises. In the light of these analyses, an interpretation of the São Gens site is offered in conclusion
Role of Mesenchymal Stem Cells in Counteracting Oxidative Stress\u2014Related Neurodegeneration
Neurodegenerative diseases include a variety of pathologies such as Alzheimer\u2019s
disease, Parkinson\u2019s disease, Huntington\u2019s disease, amyotrophic lateral sclerosis, and so forth,
which share many common characteristics such as oxidative stress, glycation, abnormal protein
deposition, inflammation, and progressive neuronal loss. The last century has witnessed significant
research to identify mechanisms and risk factors contributing to the complex etiopathogenesis of
neurodegenerative diseases, such as genetic, vascular/metabolic, and lifestyle-related factors, which
often co-occur and interact with each other. Apart from several environmental or genetic factors,
in recent years, much evidence hints that impairment in redox homeostasis is a common mechanism
in different neurological diseases. However, from a pharmacological perspective, oxidative stress is a
difficult target, and antioxidants, the only strategy used so far, have been ineffective or even provoked
side effects. In this review, we report an analysis of the recent literature on the role of oxidative stress
in Alzheimer\u2019s and Parkinson\u2019s diseases as well as in amyotrophic lateral sclerosis, retinal ganglion
cells, and ataxia. Moreover, the contribution of stem cells has been widely explored, looking at their
potential in neuronal differentiation and reporting findings on their application in fighting oxidative
stress in different neurodegenerative diseases. In particular, the exposure to mesenchymal stem cells
or their secretome can be considered as a promising therapeutic strategy to enhance antioxidant
capacity and neurotrophin expression while inhibiting pro-inflammatory cytokine secretion, which
are common aspects of neurodegenerative pathologies. Further studies are needed to identify a
tailored approach for each neurodegenerative disease in order to design more effective stem cell
therapeutic strategies to prevent a broad range of neurodegenerative disorder
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