5,338 research outputs found
Parametric resonance for antineutrino conversions using LSND best-fit results with a 3+1 flavor scheme
An analytical solution to a parametric resonance effect for antineutrinos in
a 3+1 flavor (active+sterile) scheme using multiple non-adiabatic density
shifts is presented. We derive the conditions for a full flavor conversion for
antineutrino oscillations
under the assumption that LSND best-fits for the mixing
parameters are valid in a short-baseline accelerator experiment. We show that
the parametric resonance effect can be exploited to increase the effective
antineutrino oscillation length by a factor of 10-40, thus sustaining a high
oscillation probability for a much longer period of time than in the vacuum
scenario. We propose a realistic experimental setup that could probe for this
effect which leaves a signature in terms of a specific oscillation probability
profile. Moreover, since the parametric resonance effect is valid in any 2 or
1+1 flavor approximation, our results could be suggestive for future
short-baseline accelerator neutrino detection experiments.Comment: 6 pages, 4 figure
Strong Gravitational Lensing and Dark Energy Complementarity
In the search for the nature of dark energy most cosmological probes measure
simple functions of the expansion rate. While powerful, these all involve
roughly the same dependence on the dark energy equation of state parameters,
with anticorrelation between its present value w_0 and time variation w_a.
Quantities that have instead positive correlation and so a sensitivity
direction largely orthogonal to, e.g., distance probes offer the hope of
achieving tight constraints through complementarity. Such quantities are found
in strong gravitational lensing observations of image separations and time
delays. While degeneracy between cosmological parameters prevents full
complementarity, strong lensing measurements to 1% accuracy can improve
equation of state characterization by 15-50%. Next generation surveys should
provide data on roughly 10^5 lens systems, though systematic errors will remain
challenging.Comment: 7 pages, 5 figure
The biochemical, physiological, and metabolic evaluation of human subjects in a life support systems evaluator and on a liquid food diet Final report, 12 Jun. 1964 - 23 Feb. 1965
Biochemical, physiological, and metabolic analysis of subjects in life support system on liquid food diets during space environment simulatio
Evaluation of trends in derived snowfall and rainfall across Eurasia and linkages with discharge to the Arctic Ocean
To more fully understand the role of precipitation in observed increases in freshwater discharge to the Arctic Ocean, data from a new archive of bias-adjusted precipitation records for the former USSR (TD9813), along with the CRU and Willmott-Matsuura data sets, were examined for the period 1936–1999. Across the six largest Eurasian river basins, snowfall derived from TD9813 exhibits a strongly significant increase until the late 1950s and a moderately significant decrease thereafter. A strongly significant decline in derived rainfall is also noted. Spatially, snowfall increases are found primarily across north-central Eurasia, an area where the rainfall decreases are most prominent. Although no significant change is determined in Eurasian-basin snowfall over the entire 64 year period, we note that interpolation from early, uneven station networks causes an overestimation of spatial precipitation, and that the local snowfall trends determined from gridded TD9813 data are likely underestimated. Yet, numerous uncertainties in historical Arctic climate data and the sparse, irregular nature of Arctic station networks preclude a confident assessment of precipitation-discharge linkages during the period of reported discharge trends
Comparison of organoleptic acceptability of liquid and fresh diets
Organoleptic acceptability of liquid and fresh diets for space flight feedin
Quantum transport in noncentrosymmetric superconductors and thermodynamics of ferromagnetic superconductors
We consider a general Hamiltonian describing coexistence of itinerant
ferromagnetism, spin-orbit coupling and mixed spin-singlet/triplet
superconducting pairing in the context of mean-field theory. The Hamiltonian is
diagonalized and exact eigenvalues are obtained, thus allowing us to write down
the coupled gap equations for the different order parameters. Our results may
then be applied to any model describing coexistence of any combination of these
three phenomena. As a specific application of our results, we consider
tunneling between a normal metal and a noncentrosymmetric superconductor with
mixed singlet and triplet gaps. The conductance spectrum reveals information
about these gaps in addition to how the influence of spin-orbit coupling is
manifested. We also consider the coexistence of itinerant ferromagnetism and
triplet superconductivity as a model for recently discovered ferromagnetic
superconductors. The coupled gap equations are solved self-consistently, and we
study the conditions necessary to obtain the coexistent regime of
ferromagnetism and superconductivity. Analytical expressions are presented for
the order parameters, and we provide an analysis of the free energy to identify
the preferred system state. Moreover, we make specific predictions concerning
the heat capacity for a ferromagnetic superconductor. In particular, we report
a nonuniversal relative jump in the specific heat, depending on the
magnetization of the system, at the uppermost superconducting phase transition.
[Shortened abstract due to arXiv submission.]Comment: 19 pages, 15 figures (high quality figures available in published
version). Accepted for publication in Phys. Rev.
Quasar Proper Motions and Low-Frequency Gravitational Waves
We report observational upper limits on the mass-energy of the cosmological
gravitational-wave background, from limits on proper motions of quasars.
Gravitational waves with periods longer than the time span of observations
produce a simple pattern of apparent proper motions over the sky, composed
primarily of second-order transverse vector spherical harmonics. A fit of such
harmonics to measured motions yields a 95%-confidence limit on the mass-energy
of gravitational waves with frequencies <2e-9 Hz, of <0.11/h*h times the
closure density of the universe.Comment: 15 pages, 1 figure. Also available at
http://charm.physics.ucsb.edu:80/people/cgwinn/cgwinn_group/index.htm
Influence of processed Halyomorpha halys bugs on the aroma and taste of 'Chardonnay' and 'Merlot' musts and wines
Native to East Asia, the invasive brown marmorated stink bug (Halyomorpha halys) was accidentally introduced into Switzerland around 2004 and is now spreading all over Europe. This pentatomid is highly polyphagous and attacks vegetables, field and tree crops as well as soft fruits. Moreover, all development stages of H. halys are found in vineyards, suggesting that grapevine is also a host plant for this insect. Nonetheless, its actual effects on European wine production is unclear. As such, we studied the impact of processed H. halys on the aroma and taste of grape musts and wines. We artificially contaminated 'Chardonnay' and 'Merlot' grapes with up to ten H. halys nymphs and adults per kg grapes directly before the vintage was crushed. In the freshly pressed must, the addition of 1 living bug/kg grapes did not affect the olfactory sensation of the 'Chardonnay' juice. However, the aroma and taste of 'Chardonnay' and 'Merlot' musts contaminated with 3 to 10 H. halys individuals/kg grapes could be distinguished from the uncontaminated control juices and were perceived as vegetal and woody. Yet after bottling, the different wines with 0 to 10 H. halys individuals/kg grapes could no longer be differentiated from each other in 2-out-of-5 discrimination tests. Amongst 17 rated organoleptic descriptors to characterise the sensory profile of the four 'Chardonnay' wines, only two showed significant differences; the colour intensity increased and wines’ finesse decreased with the number of added bugs. For the three 'Merlot' wines, none of the 21 organoleptic descriptors of the sensory profiles differed significantly. In addition, winegrowers did not dislike H. halys contaminated 'Chardonnay' and 'Merlot' wines compared to their uncontaminated controls one year after bottling. It therefore seems that the molecules responsible for the off-flavours in contaminated musts volatilise to a large part during the fermentation process. Our results consequently indicate that a contamination of the vintage with H. halys has the potential to alter the quality of grape musts and potentially grape juices but that there is little risk for influencing the taste of processed wines. Nonetheless, we recommend monitoring the development of H. halys in vineyards in order to anticipate quantitative and qualitative problems at harvest
Reducing Zero-point Systematics in Dark Energy Supernova Experiments
We study the effect of filter zero-point uncertainties on future supernova
dark energy missions. Fitting for calibration parameters using simultaneous
analysis of all Type Ia supernova standard candles achieves a significant
improvement over more traditional fit methods. This conclusion is robust under
diverse experimental configurations (number of observed supernovae, maximum
survey redshift, inclusion of additional systematics). This approach to
supernova fitting considerably eases otherwise stringent mission calibration
requirements. As an example we simulate a space-based mission based on the
proposed JDEM satellite; however the method and conclusions are general and
valid for any future supernova dark energy mission, ground or space-based.Comment: 30 pages,8 figures, 5 table, one reference added, submitted to
Astroparticle Physic
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