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Forecasting near-surface weather conditions and precipitation in Alaska’s Prince William Sound with the PWS-WRF modeling system
In the summer of 2009, several scientific teams engaged in a field program in Prince William Sound (PWS), Alaska to test an end-to-end atmosphere/ocean prediction system specially designed for this region. The “Sound Predictions Field Experiment” (FE) was a test of the PWS-Observing System (PWS-OS) and the culmination of a five-year program to develop an observational and prediction system for the Sound. This manuscript reports on results of an 18-day high-resolution atmospheric forecasting field project using the Weather Research and Forecasting (WRF) model.
Special attention was paid to surface meteorological properties and precipitation. Upon reviewing the results of the real-time forecasts, modifications were incorporated in the PWS-WRF modeling system in an effort to improve objective forecast skill. Changes were both geometric (model grid structure) and physical (different physics parameterizations).
The weather during the summer-time FE was typical of the PWS in that it was characterized by a number of minor disturbances rotating around an anchored low, but with no major storms in the Gulf of Alaska. The basic PWS-WRF modeling system as implemented operationally for the FE performed well, especially considering the extremely complex terrain comprising the greater PWS region.
Modifications to the initial PWS-WRF modeling system showed improvement in predicting surface variables, especially where the ambient flow interacted strongly with the terrain. Prediction of precipitation on an accumulated basis was more accurate than prediction on a day-to-day basis. The 18-day period was too short to provide reliable assessment and intercomparison of the quantitative precipitation forecasting (QPF) skill of the PWS-WRF model variants
Nonequilibrium Phase Transitions of Vortex Matter in Three-Dimensional Layered Superconductors
Large-scale simulations on three-dimensional (3D) frustrated anisotropic XY
model have been performed to study the nonequilibrium phase transitions of
vortex matter in weak random pinning potential in layered superconductors. The
first-order phase transition from the moving Bragg glass to the moving smectic
is clarified, based on thermodynamic quantities. A washboard noise is observed
in the moving Bragg glass in 3D simulations for the first time. It is found
that the activation of the vortex loops play the dominant role in the dynamical
melting at high drive.Comment: 3 pages,5 figure
Finite-temperature resistive transition in the two-dimensional XY gauge glass model
We investigate numerically the resistive transition in the two-dimensional XY
gauge glass model. The resistively-shunted junction dynamics subject to the
fluctuating twist boundary condition is used and the linear resistances in the
absence of an external current at various system sizes are computed. Through
the use of the standard finite-size scaling method, the finite temperature
resistive transition is found at (in units of the Josephson
coupling strength) with dynamic critical exponent and the static
exponent , in contrast to widely believed expectation of the
zero-temperature transition. Comparisons with existing experiments and
simulations are also made.Comment: 5 pages in two columns, 4 eps figures included, to appear in PR
Kosterlitz-Thouless transition of quantum XY model in two dimensions
The two-dimensional XY model is investigated with an extensive
quantum Monte Carlo simulation. The helicity modulus is precisely estimated
through a continuous-time loop algorithm for systems up to
near and below the critical temperature. The critical temperature is estimated
as . The obtained estimates for the helicity modulus
are well fitted by a scaling form derived from the Kosterlitz renormalization
group equation. The validity of the Kosterlitz-Thouless theory for this model
is confirmed.Comment: 8 pages, 2 tables, 6 figure
Multicritical behavior in the fully frustrated XY model and related systems
We study the phase diagram and critical behavior of the two-dimensional
square-lattice fully frustrated XY model (FFXY) and of two related models, a
lattice discretization of the Landau-Ginzburg-Wilson Hamiltonian for the
critical modes of the FFXY model, and a coupled Ising-XY model. We present a
finite-size-scaling analysis of the results of high-precision Monte Carlo
simulations on square lattices L x L, up to L=O(10^3).
In the FFXY model and in the other models, when the transitions are
continuous, there are two very close but separate transitions. There is an
Ising chiral transition characterized by the onset of chiral long-range order
while spins remain paramagnetic. Then, as temperature decreases, the systems
undergo a Kosterlitz-Thouless spin transition to a phase with quasi-long-range
order.
The FFXY model and the other models in a rather large parameter region show a
crossover behavior at the chiral and spin transitions that is universal to some
extent. We conjecture that this universal behavior is due to a multicritical
point. The numerical data suggest that the relevant multicritical point is a
zero-temperature transition. A possible candidate is the O(4) point that
controls the low-temperature behavior of the 4-vector model.Comment: 62 page
Nature of Phase Transitions of Superconducting Wire Networks in a Magnetic Field
We study - characteristics of periodic square Nb wire networks as a
function of temperature in a transverse magnetic field, with a focus on three
fillings 2/5, 1/2, and 0.618 that represent very different levels of
incommensurability. For all three fillings, a scaling behavior of -
characteristics is found, suggesting a finite temperature continuous
superconducting phase transition. The low-temperature - characteristics
are found to have an exponential form, indicative of the domain-wall
excitations.Comment: 5 pages, also available at
http://www.neci.nj.nec.com/homepages/tang.htm
State history and economic development: evidence from six millennia
The presence of a state is one of the most reliable historical predictors of social and economic development. In this article, we complete the coding of an extant indicator of state presence from 3500 BCE forward for almost all but the smallest countries of the world today. We outline a theoretical framework where accumulated state experience increases aggregate productivity in individual countries but where newer or relatively inexperienced states can reach a higher productivity maximum by learning from the experience of older states. The predicted pattern of comparative development is tested in an empirical analysis where we introduce our extended state history variable. Our key finding is that the current level of economic development across countries has a hump-shaped relationship with accumulated state history
No Detectable Fertility Benefit from a Single Additional Mating in Wild Stalk-Eyed Flies
Background: Multiple mating by female insects is widespread, and the explanation(s) for repeated mating by females has been the subject of much discussion. Females may profit from mating multiply through direct material benefits that increase their own reproductive output, or indirect genetic benefits that increase offspring fitness. One particular direct benefit that has attracted significant attention is that of fertility assurance, as females often need to mate multiply to achieve high fertility. This hypothesis has never been tested in a wild insect population.Methodology/Principal Findings: Female Malaysian stalk-eyed flies (Teleopsis dalmanni) mate repeatedly during their lifetime, and have been shown to be sperm limited under both laboratory and field conditions. Here we ask whether receiving an additional mating alleviates sperm limitation in wild females. In our experiment one group of females received a single additional mating, while a control group received an interrupted, and therefore unsuccessful, mating. Females that received an additional mating did not lay more fertilised eggs in total, nor did they lay proportionately more fertilised eggs. Female fertility declined significantly through time, demonstrating that females were sperm limited. However, receipt of an additional mating did not significantly alter the rate of this decline.Conclusions/Significance: Our data suggest that the fertility consequences of a single additional mating were small. We discuss this effect (or lack thereof), and suggest that it is likely to be attributed to small ejaculate size, a high proportion of failed copulations, and the presence of X-linked meiotic drive in this species
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