110,954 research outputs found
Aspects of Neutrino Interactions (Scattering at small - Region)
The article begins with a description of chiral symmetry and its application
to neutrino induced reactions. For small (forward direction) the process
is dominated by the amplitute with helicity zero where the pion pole disappears
when multiplied with the polarization vector. The remaining part of the
amplitude is determined by PCAC. For GeV the computed cross
sections are in good agreement with data. In coherent pion production we expect
equal yields for neutrinos and antineutrinos a relation which for
GeV is fulfilled. We discuss specific features of the data and suggest methods
for improving them by presenting new estimates for the incoherent background.Comment: Presented at the CETUP-Workshop on Neutrino Interactions, July 22-31,
2014 at Lead/Dead Wood, South Dakota, USA. The resubmission contains minor
correction
Comparing Heterogeneous Consumption in US and Japanese Meat and Fish Demand
This article uses national, quarterly data to conduct an empirical analysis of pre-committed meat and fish demand by US and Japanese households using the Generalized Almost Ideal Demand System (GAIDS). US consumers are found to hold pre-committed demand for beef and pork, while Japanese consumers appear to possess significant pre-committed demand for beef and fish. This provides evidence to partly explain observed differences in Japanese and US consumer reactions to non-price and non-income effects in beef, pork, poultry, and fish. In addition, the first known empirical comparison of how the GAIDS and more traditional AIDS models assess meat and fish demand is offered with both in- and out-of-sample evaluations.US/Japanese meat demand, demand forecasting, food safety, Generalized Almost Ideal Demand System, pre-committed consumption, Demand and Price Analysis,
Studies of low-energy ionic collisions Final report, 1 Oct. 1965 - 30 Sep. 1967
Ionic-molecular collisions, and collision induced dissociation of ion
A consistent spatial differencing scheme for the transonic full-potential equation in three dimensions
A full-potential steady transonic wing flow solver has been modified so that freestream density and residual are captured in regions of constant velocity. This numerically precise freestream consistency is obtained by slightly altering the differencing scheme without affecting the implicit solution algorithm. The changes chiefly affect the fifteen metrics per grid point, which are computed once and stored. With this new method, the outer boundary condition is captured accurately, and the smoothness of the solution is especially improved near regions of grid discontinuity
Gamma-ray spectrometry in the field: Radioactive heat production in the Central Slovakian Volcanic Zone
We report 62 sets of measurements from central-southern Slovakia, obtained using a modern portable gamma-ray spectrometer, which reveal the radioactive heat production in intrusive and extrusive igneous rocks of the Late Cenozoic Central Slovakian Volcanic Zone. Sites in granodiorite of the Štiavnica pluton are thus shown to have heat production in the range ~ 2.2–4.9 μW m− 3, this variability being primarily a reflection of variations in content of the trace element uranium. Sites in dioritic parts of this pluton have a lower, but overlapping, range of values, ~ 2.1–4.4 μW m− 3. Sites that have been interpreted in adjoining minor dioritic intrusions of similar age have heat production in the range ~ 1.4–3.3 μW m− 3. The main Štiavnica pluton has zoned composition, with potassium and uranium content and radioactive heat production typically increasing inward from its margins, reflecting variations observed in other granodioritic plutons elsewhere. It is indeed possible that the adjoining dioritic rocks, hitherto assigned to other minor intrusions of similar age, located around the periphery of the Štiavnica pluton, in reality provide further evidence for zonation of the same pluton. The vicinity of this pluton is associated with surface heat flow ~ 40 mW m− 2 above the regional background. On the basis of our heat production measurements, we thus infer that the pluton has a substantial vertical extent, our preferred estimate for the scale depth for its downward decrease in radioactive heat production being ~ 8 km. Nonetheless, this pluton lacks any significant negative Bouguer gravity anomaly. We attribute this to the effect of the surrounding volcanic caldera, filled with relatively low-density lavas, ‘masking’ the pluton's own gravity anomaly. We envisage that emplacement occurred when the pluton was much hotter, and thus of lower density, than at present, its continued uplift, evident from the local geomorphology, being the isostatic consequence of localized erosion. The heat production in this intrusion evidently plays a significant role, hitherto unrecognized, in the regional geothermics
Spatial control of irreversible protein aggregation
Liquid cellular compartments spatially segregate from the cytoplasm and can
regulate aberrant protein aggregation, a process linked to several medical
conditions, including Alzheimer's and Parkinson's diseases. Yet the mechanisms
by which these droplet-like compartments affect protein aggregation remain
unknown. Here, we combine kinetic theory of protein aggregation and
liquid-liquid phase separation to study the spatial control of irreversible
protein aggregation in the presence of liquid compartments. We find that, even
for weak interactions between the compartment constituents and the aggregating
monomers, aggregates are strongly enriched inside the liquid compartment
relative to the surrounding cytoplasm. We show that this enrichment is caused
by a positive feedback mechanism of aggregate nucleation and growth which is
mediated by a flux maintaining the phase equilibrium between the compartment
and the cytoplasm. Our model predicts that the compartment volume that
maximizes aggregate enrichment in the compartment is determined by the reaction
orders of aggregate nucleation. The underlying mechanism of aggregate
enrichment could be used to confine cytotoxic protein aggregates inside
droplet-like compartments suggesting potential new avenues against aberrant
protein aggregation. Our findings could also represent a common mechanism for
the spatial control of irreversible chemical reactions in general
Three-dimensional analytical magnetohydrostatic equilibria of rigidly rotating magnetospheres in cylindrical geometry
We present three-dimensional solutions of the magnetohydrostatic equations in
the co-rotating frame of reference outside a magnetized rigidly rotating
cylinder. We make no symmetry assumption for the magnetic field, but to be able
to make analytical progress we neglect outflows and specify a particular form
for the current density. The magnetohydrostatic equations can then be reduced
to a single linear partial differential equation for a pseudo-potential ,
from which the magnetic field can be calculated by differentiation. The
equation for can be solved by standard methods. The solutions can also be
used to determine the plasma pressure, density and temperature as functions of
all three spatial coordinates. Despite the obvious limitations of this
approach, it can for example be used as a simple tool to create
three-dimensional models for the closed field line regions of rotating
magnetospheres without rotational symmetry.Comment: 13 pages, 2 figures, accepted for publication by Geophysical and
Astrophysical Fluid Dynamic
Transport Anomalies and Marginal Fermi-Liquid Effects at a Quantum Critical Point
The behavior of the conductivity and the density of states, as well as the
phase relaxation time, of disordered itinerant electrons across a quantum
ferromagnetic transition is discussed. It is shown that critical fluctuations
lead to anomalies in the temperature and energy dependence of the conductivity
and the tunneling density of states, respectively, that are stronger than the
usual weak-localization anomalies in a disordered Fermi liquid. This can be
used as an experimental probe of the quantum critical behavior. The energy
dependence of the phase relaxation time at criticality is shown to be that of a
marginal Fermi liquid.Comment: 4 pp., LaTeX, no figs., requires World Scientific style files
(included), Contribution to MB1
Radiation of Angular Momentum by Neutrinos from Merged Binary Neutron Stars
We study neutrino emission from the remnant of an inspiraling binary neutron
star following coalescence. The mass of the merged remnant is likely to exceed
the stability limit of a cold, rotating neutron star. However, the angular
momentum of the remnant may also approach or even exceed the Kerr limit, J/M^2
= 1, so that total collapse may not be possible unless some angular momentum is
dissipated. We find that neutrino emission is very inefficient in decreasing
the angular momentum of these merged objects and may even lead to a small
increase in J/M^2. We illustrate these findings with a post-Newtonian,
ellipsoidal model calculation. Simple arguments suggest that the remnant may
form a bar mode instability on a timescale similar to or shorter than the
neutrino emission timescale, in which case the evolution of the remnant will be
dominated by the emission of gravitational waves.Comment: 12 pages AASTeX, 2 figures, to appear in Ap
- …