56,995 research outputs found
Infrared Lighting Does Not Suppress Catch of Codling Moth (Lepidoptera: Tortricidae) in Pheromone-Baited Monitoring Traps
Video cameras are increasingly being used to record insect behaviors in the field over prolonged intervals. A nagging question about crepuscular and nocturnal recordings is whether or not infrared light emitted by such cameras to illuminate the scene influences the behaviors of the subjects or study outcomes. Here we quantified catches of male codling moths, Cydia pomonella (L.), responding to sex pheromone-baited monitoring traps illuminated with infrared, red, white, or no light. No statistically significant differences were found between any of these treatments
Asymmetric Avalanches in the Condensate of a Zeeman-limited Superconductor
We report the non-equilibrium behavior of disordered superconducting Al films
in high Zeeman fields. We have measured the tunneling density of states of the
films through the first-order Zeeman critical field transition. We find that
films with sheet resistances of a few hundred ohms exhibit large avalanche-like
collapses of the condensate on the superheating branch of the critical field
hysteresis loop. In contrast, the transition back into the superconducting
phase (i.e., along the supercooling branch) is always continuous. The fact that
the condensate follows an unstable trajectory to the normal state suggests that
the order parameter in the hysteretic regime is not homogeneous.Comment: 5 pages, 5 figures, to appear in PR
On the fourth root prescription for dynamical staggered fermions
With the aim of resolving theoretical issues associated with the fourth root
prescription for dynamical staggered fermions in Lattice QCD simulations, we
consider the problem of finding a viable lattice Dirac operator D such that
(det D_{staggered})^{1/4} = det D. Working in the flavour field representation
we show that in the free field case there is a simple and natural candidate D
satisfying this relation, and we show that it has acceptable locality behavior:
exponentially local with localisation range vanishing ~ (a/m)^{1/2} for lattice
spacing a -> 0. Prospects for the interacting case are also discussed, although
we do not solve this case here.Comment: 29 pages, 2 figures; some revision and streamlining of the
discussions; results unchanged; to appear in PR
Poincare duality for K-theory of equivariant complex projective spaces
We make explicit Poincare duality for the equivariant K-theory of equivariant complex projective spaces. The case of the trivial group provides a new approach to the K-theory orientation
Reducing Reparameterization Gradient Variance
Optimization with noisy gradients has become ubiquitous in statistics and
machine learning. Reparameterization gradients, or gradient estimates computed
via the "reparameterization trick," represent a class of noisy gradients often
used in Monte Carlo variational inference (MCVI). However, when these gradient
estimators are too noisy, the optimization procedure can be slow or fail to
converge. One way to reduce noise is to use more samples for the gradient
estimate, but this can be computationally expensive. Instead, we view the noisy
gradient as a random variable, and form an inexpensive approximation of the
generating procedure for the gradient sample. This approximation has high
correlation with the noisy gradient by construction, making it a useful control
variate for variance reduction. We demonstrate our approach on non-conjugate
multi-level hierarchical models and a Bayesian neural net where we observed
gradient variance reductions of multiple orders of magnitude (20-2,000x)
Pole Dancing: 3D Morphs for Tree Drawings
We study the question whether a crossing-free 3D morph between two
straight-line drawings of an -vertex tree can be constructed consisting of a
small number of linear morphing steps. We look both at the case in which the
two given drawings are two-dimensional and at the one in which they are
three-dimensional. In the former setting we prove that a crossing-free 3D morph
always exists with steps, while for the latter steps
are always sufficient and sometimes necessary.Comment: Appears in the Proceedings of the 26th International Symposium on
Graph Drawing and Network Visualization (GD 2018
Universal properties of knotted polymer rings
By performing Monte Carlo sampling of -steps self-avoiding polygons
embedded on different Bravais lattices we explore the robustness of
universality in the entropic, metric and geometrical properties of knotted
polymer rings. In particular, by simulating polygons with up to we
furnish a sharp estimate of the asymptotic values of the knot probability
ratios and show their independence on the lattice type. This universal feature
was previously suggested although with different estimates of the asymptotic
values. In addition we show that the scaling behavior of the mean squared
radius of gyration of polygons depends on their knot type only through its
correction to scaling. Finally, as a measure of the geometrical
self-entanglement of the SAPs we consider the standard deviation of the writhe
distribution and estimate its power-law behavior in the large limit. The
estimates of the power exponent do depend neither on the lattice nor on the
knot type, strongly supporting an extension of the universality property to
some features of the geometrical entanglement.Comment: submitted to Phys.Rev.
Exchange Field-Mediated Magnetoresistance in the Correlated Insulator Phase of Be Films
We present a study of the proximity effect between a ferromagnet and a
paramagnetic metal of varying disorder. Thin beryllium films are deposited onto
a 5 nm-thick layer of the ferromagnetic insulator EuS. This bilayer arrangement
induces an exchange field, , of a few tesla in low resistance Be films
with sheet resistance , where is the quantum resistance.
We show that survives in very high resistance films and, in fact,
appears to be relatively insensitive to the Be disorder. We exploit this fact
to produce a giant low-field magnetoresistance in the correlated insulator
phase of Be films with .Comment: To be published in Physical Review Letter
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