1,649 research outputs found
Evaluation of expected solar flare neutrino events in the IceCube observatory
Since the end of the eighties and in response to a reported increase in the
total neutrino flux in the Homestake experiment in coincidence with a solar
flare, solar neutrino detectors have searched for solar flare signals.
Neutrinos from the decay of mesons, which are themselves produced in collisions
of accelerated protons with the solar atmosphere, would provide a novel window
on the underlying physics of the acceleration process. For our studies we focus
on the IceCube Neutrino Observatory, a cubic kilometer neutrino detector
located at the geographical South Pole. Due to its Supernova data acquisition
system and its DeepCore component, dedicated to low energy neutrinos, IceCube
may be sensitive to solar flare neutrinos and thus permit either a measurement
of the signal or the establishment of more stringent upper limits on the solar
flare neutrino flux. We present an approach for a time profile analysis based
on a stacking method and an evaluation of a possible solar flare signal in
IceCube using the Geant4 toolkit.Comment: Paper submitted to the 34th International Cosmic Ray Conference, The
Hague 201
Heliospheric Transport of Neutron-Decay Protons
We report on new simulations of the transport of energetic protons
originating from the decay of energetic neutrons produced in solar flares.
Because the neutrons are fast-moving but insensitive to the solar wind magnetic
field, the decay protons are produced over a wide region of space, and they
should be detectable by current instruments over a broad range of longitudes
for many hours after a sufficiently large gamma-ray flare. Spacecraft closer to
the Sun are expected to see orders-of magnitude higher intensities than those
at the Earth-Sun distance. The current solar cycle should present an excellent
opportunity to observe neutron-decay protons with multiple spacecraft over
different heliographic longitudes and distances from the Sun.Comment: 12 pages, 4 figures, to be published in special issue of Solar
Physic
Prevalence of Physical Activity and Sedentary Behavior Among Stroke Survivors in the United States
The risk of stroke is greatest among adults who have experienced a previous stroke, transient ischemic attack, or myocardial infarction. Physical activity may reduce the secondary risk of stroke through mediating effects on blood pressure, vasoconstriction, and circulating lipid concentrations; however, little is known about the prevalence of physical activity and sedentary behavior among stroke survivors in the United States
Detection of the high energy component of Jovian electrons in Low Earth Orbit with the PAMELA experiment
The PAMELA experiment is devoted to the study of cosmic rays in Low Earth
Orbit with an apparatus optimized to perform a precise determination of the
galactic antimatter component of c.r. It is constituted by a number of
detectors built around a permanent magnet spectrometer. PAMELA was launched in
space on June 15th 2006 on board the Russian Resurs-DK1 satellite for a mission
duration of three years. The characteristics of the detectors, the long
lifetime and the orbit of the satellite, will allow to address several aspects
of cosmic-ray physics. In this work we discuss the observational capabilities
of PAMELA to detect the electron component above 50 MeV. The magnetic
spectrometer allows a detailed measurement of the energy spectrum of electrons
of galactic and Jovian origin. Long term measurements and correlations with
Earth-Jupiter 13 months synodic period will allow to separate these two
contributions and to measure the primary electron Jovian component, dominant in
the 50-70 MeV energy range. With this technique it will also be possible to
study the contribution to the electron spectrum of Jovian e- reaccelerated up
to 2 GeV at the Solar Wind Termination Shock.Comment: On behalf of PAMELA collaboration. Accepted for publication on
Advances in Space Researc
A comparison of alternative assays to measure DNA damage in stallion spermatozoa: TUNEL test versus ‘Nicoletti assay’
The aberrations of sperm DNA may cause various problems and have negative consequences on fertility. These influence embryonic development or might lead to early embryo loss. Sperm Chromatin Structure Assay (SCSA) is the flow cytometric method most often used for the detection of DNA lesions; however, some studies using that method reached confusing conclusions. The aim of this pilot study was to adjust and compare two alternative tests, namely the TUNEL test and the Nicoletti assay. The above-mentioned two flow cytometric methods capable of detecting the fragmented DNA of sperm were tested on 12 frozen-thawed stallion semen samples. The TUNEL test demonstrated much higher DNA fragmentation ratio than the Nicoletti assay (mean ± SD: 30.77 ± 13.03% vs. 1.93 ± 0.89%, respectively). A fluorescent microscopic check of the samples showed that TUNEL labelled the plasma membrane and the mitochondria in a nonspecific way, rather than detecting only the fragmented DNA, thus eventually resulting in a false positive sign. The Nicoletti assay is simpler, quicker and does not detect nonspecific binding; however, further analyses are required to determine its diagnostic value
Cosmic ray short burst observed with the Global Muon Detector Network (GMDN) on June 22, 2015
We analyze the short cosmic ray intensity increase ("cosmic ray burst": CRB)
on June 22, 2015 utilizing a global network of muon detectors and derive the
global anisotropy of cosmic ray intensity and the density (i.e. the
omnidirectional intensity) with 10-minute time resolution. We find that the CRB
was caused by a local density maximum and an enhanced anisotropy of cosmic rays
both of which appeared in association with Earth's crossing of the heliospheric
current sheet (HCS). This enhanced anisotropy was normal to the HCS and
consistent with a diamagnetic drift arising from the spatial gradient of cosmic
ray density, which indicates that cosmic rays were drifting along the HCS from
the north of Earth. We also find a significant anisotropy along the HCS,
lasting a few hours after the HCS crossing, indicating that cosmic rays
penetrated into the inner heliosphere along the HCS. Based on the latest
geomagnetic field model, we quantitatively evaluate the reduction of the
geomagnetic cut-off rigidity and the variation of the asymptotic viewing
direction of cosmic rays due to a major geomagnetic storm which occurred during
the CRB and conclude that the CRB is not caused by the geomagnetic storm, but
by a rapid change in the cosmic ray anisotropy and density outside the
magnetosphere.Comment: accepted for the publication in the Astrophysical Journa
Prevalence of Physical Activity and Sedentary Behavior Among Adults With Cardiovascular Disease in the United States
Physical activity (PA) is recommended for primary and secondary prevention of cardiovascular disease (CVD). This study described the prevalence of self-reported and accelerometer-measured PA and sedentary behavior using a nationally representative sample from the United States, a subset of whom had CVD, including angina, coronary heart disease (CHD), congestive heart failure (CHF), and myocardial infarction (MI)
Public Perceptions of Wildlife-Associated Disease: Risk Communication Matters
Wildlife professionals working at the interface where conflicts arise between people and wild animals have an exceptional responsibility in the long-term interest of sustaining society’s support for wildlife and its conservation by resolving human–wildlife conflicts so that people continue to view wildlife as a valued resource. The challenge of understanding and responding to people’s concerns about wildlife is particularly acute in situations involving wildlife-associated disease and may be addressed through One Health communication. Two important questions arise in this work: (1) how will people react to the message that human health and wildlife health are linked?; and (2) will wildlife-associated disease foster negative attitudes about wildlife as reservoirs, vectors, or carriers of disease harmful to humans? The answers to these questions will depend in part on whether wildlife professionals successfully manage wildlife disease and communicate the associated risks in a way that promotes societal advocacy for healthy wildlife rather than calls for eliminating wildlife because they are viewed as disease-carrying pests. This work requires great care in both formal and informal communication. We focus on risk perception, and we briefly discuss guidance available for risk communication, including formation of key messages and the importance of word choices. We conclude that the risk perception and communication research available is helpful but inadequate, and that thoughtful practice with respect to message and word choice is needed
The problem of a metal impurity in an oxide: ab-initio study of electronic and structural properties of Cd in Rutile TiO2
In this work we undertake the problem of a transition metal impurity in an
oxide. We present an ab-initio study of the relaxations introduced in TiO2 when
a Cd impurity replaces substitutionally a Ti atom. Using the Full-Potential
Linearized-Augmented-Plane-Wave method we obtain relaxed structures for
different charge states of the impurity and computed the electric-field
gradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are
dependent on the charge state of the impurity. This dependence is very
remarkable in the case of the EFG and is explained analyzing the electronic
structure of the studied system. We predict fairly anisotropic relaxations for
the nearest oxygen neighbors of the Cd impurity. The experimental confirmation
of this prediction and a brief report of these calculations have recently been
presented [P.R.L. 89, 55503 (2002)]. Our results for relaxations and EFGs are
in clear contradiction with previous studies of this system that assumed
isotropic relaxations and point out that no simple model is viable to describe
relaxations and the EFG at Cd in TiO2 even approximately.Comment: 11 pages, 8 figures, Revtex 4, published in Physical Review
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