708 research outputs found
Total nuclear disarmament: ethical and moral issues
Moving focus from the geostrategic and political realms to ethical and moral ones can lead to a better understanding of the paradox of “guaranteeing peace” by means of implementing an . infrastructure for the extinction of mankind (i.e. the nuclear weapons industry). A possible way forward is derived from this major paradigm shift. The analysis is contextualized within the broader scope of questioning the implicit legitimization of unrestrained tampering with nature, from matter to life
Reduction of Movement in Neurological Diseases: Effects on Neural Stem Cells Characteristics.
Both astronauts and patients affected by chronic movement-limiting pathologies face impairment in muscle and/or brain performance. Increased patient survival expectations and the expected longer stays in space by astronauts may result in prolonged motor deprivation and consequent pathological effects. Severe movement limitation can influence not only the motor and metabolic systems but also the nervous system, altering neurogenesis and the interaction between motoneurons and muscle cells. Little information is yet available about the effect of prolonged muscle disuse on neural stem cells characteristics. Our in vitro study aims to fill this gap by focusing on the biological and molecular properties of neural stem cells (NSCs). Our analysis shows that NSCs derived from the SVZ of HU mice had shown a reduced proliferation capability and an altered cell cycle. Furthermore, NSCs obtained from HU animals present an incomplete differentiation/maturation. The overall results support the existence of a link between reduction of exercise and muscle disuse and metabolism in the brain and thus represent valuable new information that could clarify how circumstances such as the absence of load and the lack of movement that occurs in people with some neurological diseases, may affect the properties of NSCs and contribute to the negative manifestations of these conditions
Molecular biology of the apteronotus NMDA receptor NR1 subunit
The complete sequences and expression patterns of the NR1 (aptNR1) subunit of the N-methyl-d-aspartate (NMDA) receptor and its alternative splice isoforms have been determined for the weakly electric fish Apteronotus leptorhynchus. The deduced amino acid sequence of aptNR1 is approximately 88 % identical to the NR1 sequences of other vertebrate. Two of the three alternative splice cassettes previously described for mammalian NR1s, N1 and C1, are present in aptNR1, but the third cassette, C2, is not found. In addition, two teleost-specific splice cassettes occur on the N-terminal side of the C1 sequence. The cellular patterns of aptNR1 expression, including the patterns of N1 and C1 splicing, have been mapped using the in situ hybridization technique. High levels of aptNR1 mRNA were detected throughout the central nervous system including most neurons of the electrosensory system, with the highest levels in electrosensory lateral line lobe pyramidal cells. Expression of the N1 splice isoform was higher in more caudal regions of the brain, and expression of the C1 splice isoform was higher in more rostral regions. The N1 splice isoform was present in almost all NR1-positive cells, in contrast to the C1 splice isoform which was restricted to a subset of NR1-positive cells. These results demonstrate that the NR1 subunit of the NMDA receptor is evolutionarily conserved across species and that regulation of alternative RNA splicing modulates the properties of NR1 in different neurons of the central nervous system of A. leptorhynchus
Equating Accelerometer Estimates of Moderate-to-Vigorous Physical Activity: In Search of the Rosetta Stone
Purpose - No universally accepted ActiGraph accelerometer cutpoints for quantifying moderate-to-vigorous physical activity (MVPA) exist. Estimates of MVPA from one set of cutpoints cannot be directly compared to MVPA estimates using different cutpoints, even when the same outcome units are reported (MVPA min•d-1). The purpose of this study was to illustrate the utility of an equating system that translates reported MVPA estimates from one set of cutpoints into another, to better inform public health policy.
Design - Secondary data analysis.
Methods - ActiGraph data from a large preschool project (N=419, 3-6yr-olds, CHAMPS) was used to conduct the analyses. Conversions were made among five different published MVPA cutpoints for children: Pate (PT), Sirard (SR), Puyau (PY), Van Cauwengerghe (VC), and Freedson Equation (FR). A 10 fold cross-validation procedure was used to develop prediction equations using MVPA estimated from each of the five sets of cutpoints as the dependent variable, with estimated MVPA from one of the other four sets of cutpoints (e.g., PT MVPA predicted from FR MVPA).
Results - The mean levels of MVPA for the total sample ranged from 22.5 (PY) to 269.0 (FR) min•d-1. Across the prediction models (5 total), the median proportion of variance explained (R2) was 0.76 (range 0.48-0.97). The median absolute percent error was 17.2% (range 6.3%-38.4%).
Conclusion - The prediction equations developed here allow for direct comparisons between studies employing different ActiGraph cutpoints in preschool-age children. These prediction equations give public health researchers and policy makers a more concise picture of physical activity levels of preschool-aged children
ESAF: Full Simulation of Space-Based Extensive Air Showers Detectors
Future detection of Extensive Air Showers (EAS) produced by Ultra High Energy
Cosmic Particles (UHECP) by means of space based fluorescence telescopes will
open a new window on the universe and allow cosmic ray and neutrino astronomy
at a level that is virtually impossible for ground based detectors. In this
paper we summarize the results obtained in the context of the EUSO project by
means of a detailed Monte Carlo simulation of all the physical processes
involved in the fluorescence technique, from the Extensive Air Shower
development to the instrument response. Particular emphasis is given to
modeling the light propagation in the atmosphere and the effect of clouds. Main
results on energy threshold and resolution, direction resolution and Xmax
determination are reported. Results are based on EUSO telescope design, but are
also extended to larger and more sensitive detectors.Comment: 38 pages, 48 figures Corrected typos. Changed content. Added figure
Tracing very high energy neutrinos from cosmological distances in ice
Astrophysical sources of ultrahigh energy neutrinos yield tau neutrino fluxes
due to neutrino oscillations. We study in detail the contribution of tau
neutrinos with energies above PeV relative to the contribution of the other
flavors. We consider several different initial neutrino fluxes and include tau
neutrino regeneration in transit through the Earth and energy loss of charged
leptons. We discuss signals of tau neutrinos in detectors such as IceCube, RICE
and ANITA.Comment: 27 pages, 19 figure
Propagation of Muons and Taus at High Energies
The photonuclear contribution to charged lepton energy loss has been
re-evaluated taking into account HERA results on real and virtual photon
interactions with nucleons. With large processes incorporated, the
average muon range in rock for muon energies of GeV is reduced by only
5% as compared with the standard treatment. We have calculated the tau energy
loss for energies up to GeV taking into consideration the decay of the
tau. A Monte Carlo evaluation of tau survival probability and range show that
at energies below GeV, depending on the material, only tau decays
are important. At higher energies the tau energy losses are significant,
reducing the survival probability of the tau. We show that the average range
for tau is shorter than its decay length and reduce to 17 km in water for an
incident tau energy of GeV, as compared with its decay length of 49 km
at that energy. In iron, the average tau range is 4.7 km for the same incident
energy.Comment: 25 pages including 8 figure
Physical activity outcomes in afterschool programs: A group randomized controlled trial
Afterschool programs (ASPs) across the US are working towards achieving the standard of all children accumulating 30minutes of moderate-to-vigorous physical activity (MVPA) during program time. This study describes the two-year impact of an intervention designed to assist ASPs meeting the 30min/d MVPA standard
Reduction of Movement in Neurological Diseases : Effects on Neural Stem Cells Characteristics
Both astronauts and patients affected by chronic movement-limiting pathologies face
impairment in muscle and/or brain performance. Increased patient survival expectations
and the expected longer stays in space by astronauts may result in prolonged motor
deprivation and consequent pathological effects. Severe movement limitation can
influence not only the motor and metabolic systems but also the nervous system,
altering neurogenesis and the interaction between motoneurons and muscle cells. Little
information is yet available about the effect of prolonged muscle disuse on neural stem
cells characteristics. Our in vitro study aims to fill this gap by focusing on the biological
and molecular properties of neural stem cells (NSCs). Our analysis shows that NSCs
derived from the SVZ of HU mice had shown a reduced proliferation capability and an
altered cell cycle. Furthermore, NSCs obtained from HU animals present an incomplete
differentiation/maturation. The overall results support the existence of a link between
reduction of exercise and muscle disuse and metabolism in the brain and thus represent
valuable new information that could clarify how circumstances such as the absence of
load and the lack of movement that occurs in people with some neurological diseases,
may affect the properties of NSCs and contribute to the negative manifestations of these
conditions
Tau Neutrinos Underground: Signals of Oscillations with Extragalactic Neutrinos
The appearance of high energy tau neutrinos due to
oscillations of extragalactic neutrinos can be observed by measuring the
neutrino induced upward hadronic and electromagnetic showers and upward muons.
We evaluate quantitatively the tau neutrino regeneration in the Earth for a
variety of extragalactic neutrino fluxes. Charged-current interactions of the
upward tau neutrinos below and in the detector, and the subsequent tau decay
create muons or hadronic and electromagnetic showers. The background for these
events are muon neutrino and electron neutrino charged-current and
neutral-current interactions, where in addition to extragalactic neutrinos, we
consider atmospheric neutrinos. We find significant signal to background ratios
for the hadronic/electromagnetic showers with energies above 10 TeV to 100 TeV
initiated by the extragalactic neutrinos. We show that the tau neutrinos from
point sources also have the potential for discovery above a 1 TeV threshold. A
kilometer-size neutrino telescope has a very good chance of detecting the
appearance of tau neutrinos when both muon and hadronic/electromagnetic showers
are detected.Comment: section added and two new figs; accepted for publication in Physical
Review
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