1,779 research outputs found
COMPTEL solar flare observations
COMPTEL as part of a solar target of opportunity campaign observed the sun during the period of high solar activity from 7-15 Jun. 1991. Major flares were observed on 9 and 11 Jun. Although both flares were large GOES events (greater than or = X10), they were not extraordinary in terms of gamma-ray emission. Only the decay phase of the 15 Jun. flare was observed by COMPTEL. We report the preliminary analysis of data from these flares, including the first spectroscopic measurement of solar flare neutrons. The deuterium formation line at 2.223 MeV was present in both events and for at least the 9 Jun. event, was comparable to the flux in the nuclear line region of 4-8 MeV, consistent with Solar-Maximum Mission (SSM) Observations. A clear neutron signal was present in the flare of 9 Jun. with the spectrum extending up to 80 MeV and consistent in time with the emission of gamma-rays, confirming the utility of COMPTEL in measuring the solar neutron flux at low energies. The neutron flux below 100 MeV appears to be lower than that of the 3 Jun. 1982 flare by more than an order of magnitude. The neutron signal of the 11 Jun. event is under study. Severe dead time effects resulting from the intense thermal x-rays require significant corrections to the measured flux which increase the magnitude of the associated systematic uncertainties
New Forms of Deuteron Equations and Wave Function Representations
A recently developed helicity basis for nucleon-nucleon (NN) scattering is
applied to th e deuteron bound state. Here the total spin of the deuteron is
treated in such a helicity representation. For the bound state, two sets of two
coupled eigenvalue equations are developed, where the amplitudes depend on two
and one variable, respectively. Numerical illustrations based on the realistic
Bonn-B NN potential are given. In addition, an `operator form' of the deuteron
wave function is presented, and several momentum dependent spin densities are
derived and shown, in which the angular dependence is given analytically.Comment: 19 pages (Revtex), 9 fig
Analytical approximation for the sphere-sphere Coulomb potential
A simple analytical expression, which closely approximates the Coulomb
potential between two uniformly charged spheres, is presented. This expression
can be used in the optical potential semiclassical analyses which require that
the interaction be analytic on and near the real r-axis.Comment: 4 pages including 3 figures and 1 tabl
Isospin Impurity of the 4.57-MeV State in ^6Li
The T=1 isospin mixing in the 4.57-MeV (T=0) state in ^6Li is investigated via the Îą+dâ^6Li*âÎą+d* reaction and found to be less than 1%
Psychosocial resilience among left-behind adolescents in rural Thailand: A qualitative exploration
When parents migrate, they often leave children behind with relatives. Despite being at higher risk of socio-emotional problems, many left-behind children have good health and social outcomes, suggesting their resilience. We sought to understand how adolescents with internal and international migrant parents build resilience in Thailand. We conducted qualitative interviews with 24 adolescents aged 10â19, and six caregivers, parents and community leaders. Interviews were transcribed, translated and analysed, drawing on techniques from grounded theory. We found that resilience was built in a context where for many families, migration was a financial necessity and the parentâchild relationship was mainly phone-based. Adolescents built resilience using three key âresourcesâ: warmth (love and understanding), financial support and guidance. Adolescents with insecure parent or caregiver relationships, or with caring responsibilities for relatives, were less likely to have access to these resources. These adolescents sought emotional and financial independence, prioritised friendships and identified role models to obtain key resources and build resilience. The findings indicate practical and psychosocial barriers to building resilience among left-behind adolescents in Thailand. Further work could explore pathways to mental illness in this population, interventions that build peer networks and caregiverâchild relationships and the use of technology to support remote parenting
Biochemical Systematics of Notothenioid Fishes from Antarctica
Genetic variation at 30 protein-coding loci was examined in seven forms of notothenioid fishes from Antarctica. Multilocus heterozygosity varied from 0.018 to 0.078 across taxa. An analysis of the allozyme data revealed the probable existence of an unrecognized cryptic species within Trematomu5 bemacchii. Pagothenia borchgrevinki is as closely related to some species of Trematomus as are some species of Trematomus to each other. Speciation among the species of Trematomus and Pagothenia appears to have taken place primarily after the separation of Antarctica from Australia
Quantized circular motion of a trapped Bose-Einstein condensate: coherent rotation and vortices
We study the creation of vortex states in a trapped Bose-Einstein condensate
by a rotating force. For a harmonic trapping potential the rotating force
induces only a circular motion of the whole condensate around the trap center
which does not depend on the interatomic interaction. For the creation of a
pure vortex state it is necessary to confine the atoms in an anharmonic
trapping potential. The efficiency of the creation can be greatly enhanced by a
sinusodial variation of the force's angular velocity. We present analytical and
numerical calculations for the case of a quartic trapping potential. The
physical mechanism behind the requirement of an anharmonic trapping potential
for the creation of pure vortex states is explained.
[Changes: new numerical and analytical results are added and the
representation is improved.]Comment: 13 Pages, 5 Figures, RevTe
Time-of-Day Dictates Transcriptional Inflammatory Responses to Cytotoxic Chemotherapy
Many cytotoxic chemotherapeutics elicit a proinflammatory response which is often associated with chemotherapy-induced behavioral alterations. The immune system is under circadian influence; time-of-day may alter inflammatory responses to chemotherapeutics. We tested this hypothesis by administering cyclophosphamide and doxorubicin (Cyclo/Dox), a common treatment for breast cancer, to female BALB/c mice near the beginning of the light or dark phase. Mice were injected intravenously with Cyclo/Dox or the vehicle two hours after lights on (zeitgeber time (ZT2), or two hours after lights off (ZT14). Tissue was collected 1, 3, 9, and 24 hours later. Mice injected with Cyclo/Dox at ZT2 lost more body mass than mice injected at ZT14. Cyclo/Dox injected at ZT2 increased the expression of several pro-inflammatory genes within the spleen; this was not evident among mice treated at ZT14. Transcription of enzymes within the liver responsible for converting Cyclo/Dox into their toxic metabolites increased among mice injected at ZT2; furthermore, transcription of these enzymes correlated with splenic pro-inflammatory gene expression when treatment occurred at ZT2 but not ZT14. The pattern was reversed in the brain; pro-inflammatory gene expression increased among mice injected at ZT14. These data suggest that inflammatory responses to chemotherapy depend on time-of-day and are tissue specific
Computability, G\"odel's Incompleteness Theorem, and an inherent limit on the predictability of evolution
The process of evolutionary diversification unfolds in a vast genotypic space
of potential outcomes. During the past century there have been remarkable
advances in the development of theory for this diversification, and the
theory's success rests, in part, on the scope of its applicability. A great
deal of this theory focuses on a relatively small subset of the space of
potential genotypes, chosen largely based on historical or contemporary
patterns, and then predicts the evolutionary dynamics within this pre-defined
set. To what extent can such an approach be pushed to a broader perspective
that accounts for the potential open-endedness of evolutionary diversification?
There have been a number of significant theoretical developments along these
lines but the question of how far such theory can be pushed has not been
addressed. Here a theorem is proven demonstrating that, because of the digital
nature of inheritance, there are inherent limits on the kinds of questions that
can be answered using such an approach. In particular, even in extremely simple
evolutionary systems a complete theory accounting for the potential
open-endedness of evolution is unattainable unless evolution is progressive.
The theorem is closely related to G\"odel's Incompleteness Theorem and to the
Halting Problem from computability theory.Comment: Journal of the Royal Society, Interface 201
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