1,654 research outputs found
Perturbative expansions from Monte Carlo simulations at weak coupling: Wilson loops and the static-quark self-energy
Perturbative coefficients for Wilson loops and the static-quark self-energy
are extracted from Monte Carlo simulations at weak coupling. The lattice
volumes and couplings are chosen to ensure that the lattice momenta are all
perturbative. Twisted boundary conditions are used to eliminate the effects of
lattice zero modes and to suppress nonperturbative finite-volume effects due to
Z(3) phases. Simulations of the Wilson gluon action are done with both periodic
and twisted boundary conditions, and over a wide range of lattice volumes (from
to ) and couplings (from to ).
A high precision comparison is made between the simulation data and results
from finite-volume lattice perturbation theory. The Monte Carlo results are
shown to be in excellent agreement with perturbation theory through second
order. New results for third-order coefficients for a number of Wilson loops
and the static-quark self-energy are reported.Comment: 36 pages, 15 figures, REVTEX documen
Magnetic domain fluctuations in an antiferromagnetic film observed with coherent resonant soft x-ray scattering
We report the direct observation of slow fluctuations of helical
antiferromagnetic domains in an ultra-thin holmium film using coherent resonant
magnetic x-ray scattering. We observe a gradual increase of the fluctuations in
the speckle pattern with increasing temperature, while at the same time a
static contribution to the speckle pattern remains. This finding indicates that
domain-wall fluctuations occur over a large range of time scales. We ascribe
this non-ergodic behavior to the strong dependence of the fluctuation rate on
the local thickness of the film.Comment: to appear in Phys. Rev. Let
Promoting Connectivity of Network-Like Structures by Enforcing Region Separation
We propose a novel, connectivity-oriented loss function for training deep
convolutional networks to reconstruct network-like structures, like roads and
irrigation canals, from aerial images. The main idea behind our loss is to
express the connectivity of roads, or canals, in terms of disconnections that
they create between background regions of the image. In simple terms, a gap in
the predicted road causes two background regions, that lie on the opposite
sides of a ground truth road, to touch in prediction. Our loss function is
designed to prevent such unwanted connections between background regions, and
therefore close the gaps in predicted roads. It also prevents predicting false
positive roads and canals by penalizing unwarranted disconnections of
background regions. In order to capture even short, dead-ending road segments,
we evaluate the loss in small image crops. We show, in experiments on two
standard road benchmarks and a new data set of irrigation canals, that convnets
trained with our loss function recover road connectivity so well, that it
suffices to skeletonize their output to produce state of the art maps. A
distinct advantage of our approach is that the loss can be plugged in to any
existing training setup without further modifications
Making Market Rule(s)
This is the introductory essay for a special issue on the geographies of market construction and market regulation. It argues that in an age of markets, geographers ought to pay more attention to the seemingly mundane, but nevertheless socially constructed, rules that are necessary for any market to operate
thermodynamic properties of pb3u11o36
Abstract In order to progress in the development of Lead-cooled Fast Reactors, from the safety point of view it is essential to understand the chemical compatibility between liquid lead and uranium oxide. In the present work, entropy and heat capacity of Pb3U11O36, a possible ternary compound coming from fuel-coolant chemical interaction, were determined for the first time. Entropy at 298.15 K was obtained from low temperature heat capacity measurements using the Physical Property Measurement System (PPMS) in the temperature range 2–300 K, while the high temperature heat capacity has been measured by a drop calorimeter from 373 K to 1200 K. The experimental thermodynamic properties were compared with the values computed by means of DFT-GGA simulations, obtaining a very good agreement
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