5,071 research outputs found
A new proton fluence model for E greater than 10 MeV
Researchers describe a new engineering model for the fluence of protons with energies greater than 10 MeV. The data set used is a combination of observations made primarily from the Earth's surface between 1956 and 1963 and observations made from spacecraft in the vicinity of Earth between 1963 and 1985. With this data set we find that the distinction between ordinary proton events and anomalously large proton events made in earlier work disappears. The greater than 10 MeV fluences at 1 AU calculated with the new model are about twice those expected on the basis of models now in use. In contrast to earlier models, results do not depend critically on the fluence from any one event
Cosmological perturbations and noncommutative tachyon inflation
The motivation for studying the rolling tachyon and non-commutative inflation
comes from string theory. In the tachyon inflation scenario, metric
perturbations are created by tachyon field fluctuations during inflation. We
drive the exact mode equation for scalar perturbation of the metric and
investigate the cosmological perturbations in the commutative and
non-commutative inflationary spacetime driven by the tachyon field which have a
Born-Infeld Lagrangian.Comment: 6 two-column pages, no figur
A cross-cultural comparison of health-related quality of life and its associated factors among older women in Vietnam and Australia.
This study compared health-related quality of life and its associated factors among 305 women in Vietnam and 175 women in Australia aged 60-71. Descriptive analyses, Chi square, independent t-tests, and General Linear Models were used for data analysis.After controlling for socio-demographics, lifestyles, and chronic diseases, older women in Vietnam had lower levels of physical health but similar levels of mental health to those in Australia. In both populations, chronic disease and diet were associated with physical health; physical activity was related to mental health. In Australia, physical activity, exercise, and Body Mass Index were also associated with physical health; age, alcohol consumption, and sleep were also linked with mental health. In Vietnam, age and marital status were also related to physical health; chronic diseases and diet were also correlated with mental health. These findings suggested that interventions developed in Australia targeting the management of diet and physical activity, may be useful for older women in Vietnam. However, future interventions in Vietnam need to be tailored to account for different age groups, marital status, and the number of chronic diseases experienced. Further investigation into the contributions of cultural factors to health-related quality of life is recommended
GEODYN programmer's guide, volume 2, part 2
A computer program for executive control routine for orbit integration of artificial satellites is presented. At the beginning of each arc, the program initiates required constants as well as the variational partials at epoch. If epoch needs to be reset to a previous time, the program negates the stepsize, and calls for integration backward to the desired time. After backward integration is completed, the program resets the stepsize to the proper positive quantity
Asymptotic Behavior of Ext functors for modules of finite complete intersection dimension
Let be a local ring, and let and be finitely generated
-modules such that has finite complete intersection dimension. In this
paper we define and study, under certain conditions, a pairing using the
modules \Ext_R^i(M,N) which generalizes Buchweitz's notion of the Herbrand
diference. We exploit this pairing to examine the number of consecutive
vanishing of \Ext_R^i(M,N) needed to ensure that \Ext_R^i(M,N)=0 for all
. Our results recover and improve on most of the known bounds in the
literature, especially when has dimension at most two
Pair formation and collapse in imbalanced Fermion populations with unequal masses
We present an exact Quantum Monte Carlo study of the effect of unequal masses
on pair formation in Fermionic systems with population imbalance loaded into
optical lattices. We have considered three forms of the attractive interaction
and find in all cases that the system is unstable and collapses as the mass
difference increases and that the ground state becomes an inhomogeneous
collapsed state. We also address the question of canonical vs grand canonical
ensemble and its role, if any, in stabilizing certain phases
Type-1.5 Superconductors
We demonstrate the existence of a novel superconducting state in high quality
two-component MgB2 single crystalline superconductors where a unique
combination of both type-1 (kappa_1 0.707)
superconductor conditions is realized for the two components of the order
parameter. This condition leads to a vortex-vortex interaction attractive at
long distances and repulsive at short distances, which stabilizes
unconventional stripe- and gossamer-like vortex patterns that we have
visualized in this type-1.5 superconductor using Bitter decoration and also
reproduced in numerical simulations.Comment: accepted in Phys. Rev. Let
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