1,684 research outputs found
Results of the 1978 NASA/JPL balloon flight solar cell calibration program
The 1978 scheduled solar cell calibration balloon flight was successfully completed. Thirty six modules were carried to an altitude of above 36 kilometers. Recovery of telemetry and flight packages was without incident. These calibrated standard cells are used as reference standards in simulator testing of cells and arrays with similar spectral response characteristics. The factors affecting the spectral transmission of the atmosphere at various altitudes are summarized
Data management study, volume 5. Appendix A - Contractor data package technical description and system engineering /SE/ Final report
Technical description and systems engineering contractor data package for Voyager spacecraf
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Individual Differences in Dopamine Are Associated with Reward Discounting in Clinical Groups But Not in Healthy Adults.
Some people are more willing to make immediate, risky, or costly reward-focused choices than others, which has been hypothesized to be associated with individual differences in dopamine (DA) function. In two studies using PET imaging, one empirical (Study 1: N = 144 males and females across 3 samples) and one meta-analytic (Study 2: N = 307 across 12 samples), we sought to characterize associations between individual differences in DA and time, probability, and physical effort discounting in human adults. Study 1 demonstrated that individual differences in DA D2-like receptors were not associated with time or probability discounting of monetary rewards in healthy humans, and associations with physical effort discounting were inconsistent across adults of different ages. Meta-analytic results for temporal discounting corroborated our empirical finding for minimal effect of DA measures on discounting in healthy individuals but suggested that associations between individual differences in DA and reward discounting depend on clinical features. Addictions were characterized by negative correlations between DA and discounting, but other clinical conditions, such as Parkinson's disease, obesity, and attention-deficit/hyperactivity disorder, were characterized by positive correlations between DA and discounting. Together, the results suggest that trait differences in discounting in healthy adults do not appear to be strongly associated with individual differences in D2-like receptors. The difference in meta-analytic correlation effects between healthy controls and individuals with psychopathology suggests that individual difference findings related to DA and reward discounting in clinical samples may not be reliably generalized to healthy controls, and vice versa.SIGNIFICANCE STATEMENT Decisions to forgo large rewards for smaller ones due to increasing time delays, uncertainty, or physical effort have been linked to differences in dopamine (DA) function, which is disrupted in some forms of psychopathology. It remains unclear whether alterations in DA function associated with psychopathology also extend to explaining associations between DA function and decision making in healthy individuals. We show that individual differences in DA D2 receptor availability are not consistently related to monetary discounting of time, probability, or physical effort in healthy individuals across a broad age range. By contrast, we suggest that psychopathology accounts for observed inconsistencies in the relationship between measures of DA function and reward discounting behavior
Predictors of ceasing or reducing statin medication following a large increase in the consumer co-payment for medications: A retrospective observation study
Objectives: Previous Australian research has shown that following the 21% increase in the patient co-payments in 2005, the use of lipid-lowering therapy declined by 5%. This study aimed to determine the demographic and clinical characteristics of individuals who continued, reduced or ceased their use of statin medication in 2005.
Study type: Retrospective observational study using routinely collected administrative data.
Method: Pharmaceutical claims, hospital separations, and mortality records from 2000–2005 were used from the Western Australian (WA) population. The cohort comprised stable users of statin medication in 2004. We identified individuals who i) continued using statins, ii) reduced their use by ≥20%, or iii) ceased therapy for at least the first six months in 2005, based on changes in statin use between 2004 and 2005. Multivariate logistic regression models were used to determine whether the demographic and clinical characteristics of the three groups differed.
Results: There were 205 924 statin users identified in Australia in 2004. After the January 2005 Pharmaceutical Benefits Scheme (PBS) co-payment increase, 3.2% of individuals ceased their regular statin therapy, 12.9% reduced statin use and 83.9% continued statin usage. This was an increase of 2.1% in statin users reducing or ceasing therapy compared to 2004. Predictors of cessation and reduction of statin therapy included younger age, greater socio-economic disadvantage, residing in very remote areas, having general beneficiary status, being a new statin user, having no prior history of ischaemic heart disease, having no prior history of a coronary artery revascularisation procedure, taking no other cardiovascular medication or diabetic medication, taking an increased number of medications and having a lower adherence level to statin medication in 2004.
Conclusion: Compared to 2004, an additional 2.1% of statin users reduced or discontinued medication use in 2005, which may be attributed to an increase in the medication co-payment. Individuals with general beneficiary status, younger and healthier people were at particular risk of cessation or reduction in statin use in 2005
Spinless Two-Band Model in Infinite Dimensions
A spinless two-band model is studied in infinite dimension limit. Starting
from the atomic limit, the formal exact solution of the model is obtained by
means a perturbative treatment of the hopping and hybridisation terms. The
model is solved in closed form in high dimensions assuming no local spin
fluctuations. The non-Fermi liquid properties appearing in the metallic phase
are analysed through the behaviour of the density of states and the self-energy
near the Fermi level.Comment: 4 pages, 3 figures, to appear in PRB-Breif Repor
Pedestrian Approach to the Two-Channel Kondo Model
We reformulate the two-channel Kondo model to explicitly remove the
unscattered charge degrees of freedom. This procedure permits us to move the
non-Fermi liquid fixed point to infinite coupling where we can apply a
perturbative strong-coupling expansion. The fixed point Hamiltonian involves a
three-body Majorana zero mode whose scattering effects give rise to marginal
self-energies. The compactified model is the N=3 member of a family of "O(N)"
Kondo models that can be solved by semiclassical methods in the large
limit. For odd , {\em fermionic} "Kink" fluctuations about the
mean-field theory generate a fermionic -body bound-state which
asymptotically decouples at low energies. For N=3, our semi-classical methods
fully recover the non-Fermi liquid physics of the original two channel model.
Using the same methods, we find that the corresponding O(3) Kondo lattice model
develops a spin-gap and a gapless band of coherently propagating three-body
bound-states. Its strong-coupling limit offers a rather interesting realization
of marginal Fermi liquid behavior.Comment: 17 pages, Revtex 3.0. Replaced with fully compiled postscript file
Knight Shift Anomalies in Heavy Electron Materials
We calculate non-linear Knight Shift vs. susceptibility anomalies
for Ce ions possessing local moments in metals. The ions are modeled with the
Anderson Hamiltonian and studied within the non-crossing approximation (NCA).
The non-linearity diminishes with decreasing Kondo temperature
and nuclear spin- local moment separation. Treating the Ce ions as an
incoherent array in CeSn, we find excellent agreement with the observed Sn
data.Comment: 4 pages, Revtex, 3 figures available upon request from
[email protected]
Landau and dynamical instabilities of Bose-Einstein condensates with superfluid flow in a Kronig-Penney potential
We study the elementary excitations of Bose-Einstein condensates in a
one-dimensional periodic potential and discuss the stability of superfluid flow
based on the Kronig-Penney model. We analytically solve the Bogoliubov
equations and calculate the excitation spectrum. The Landau and dynamical
instabilities occur in the first condensate band when the superfluid velocity
exceeds certain critical values, which agrees with the result of condensates in
a sinusoidal potential. It is found that the onset of the Landau instability
coincides with the point where the perfect transmission of low-energy
excitations is forbidden, while the dynamical instability occurs when the
effective mass is negative. It is well known that the condensate band has a
peculiar structure called swallowtail when the periodic potential is shallow
compared to the mean field energy. We find that the upper side of the
swallowtail is dynamically unstable although the excitations have the linear
dispersion reflecting the positive effective mass.Comment: 6 pages, 2 figures, Proceedings of the International Symposium on
Quantum Fluids and Solids (QFS2006
Small Energy Scale for Mixed-Valent Uranium Materials
We investigate a two-channel Anderson impurity model with a magnetic
and a quadrupolar ground doublet, and a excited triplet. Using
the numerical renormalization group method, we find a crossover to a non-Fermi
liquid state below a temperature varying as the triplet-doublet
splitting to the 7/2 power. To within numerical accuracy, the non-linear
magnetic susceptibility and the contribution to the linear
susceptibility are given by universal one-parameter scaling functions. These
results may explain UBe as mixed valent with a small crossover scale
.Comment: 4 pages, 3 figures, REVTeX, to appear in Phys. Rev. Let
Non-Fermi Liquid Behavior in Dilute Quadrupolar System PrLaPb with 0.05
We have studied the low-temperature properties of PrLaPb
with non-Kramers quadrupolar moments of the crystal-electric-field
ground state, for a wide concentration range of Pr ions. For 0.05, the
specific heat increases monotonically below =1.5 K, which can be
scaled with a characteristic temperature defined at each concentration
. The electrical resistivity in the corresponding temperature
region shows a marked decrease deviating from a Fermi-liquid behavior
. The Kondo effect arising from the correlation
between the dilute moments and the conduction electrons may give
rise to such anomalous behavior
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