31,829 research outputs found
The Pest Status of Yellowjackets in Ohio (Hymenoptera: Vespidae)
Since 1975 in Ohio, there has been an escalation in the number of complaints and inquiries regarding yellowjackets (Vespula and Dolichovespula spp.) to the Ohio pest control operators, the Ohio Cooperative Extension Service (OCES) County Agents and the OCES Entomologists at the Ohio State University. A survey was distributed in May 1985 to both groups in order to determine the pest status of yellowjackets in Ohio. The results of this survey strongly suggest that yelIowjackets in Ohio are largely an economic pest , with most economic disturbances associated with homeowners, outdoor businesses, and outdoor recreational facilities
Indiana Ensifera (Orthopera)
(excerpt)
A total of 67 species of long-horned grasshoppers and crickets were reported to occur in Indiana by Blatchley (1903) in his Orthoptera of Indiana. Distributional information concerning thek species was sparse and has not been significantly supplemented since that time. Subsequent works which have dealt either heavily or exclusively with the Indiana fauna include Fox (1915), Blatchley (1920), Cantrall and Young (1954), and Young and Cantrall(1956)
Comment on "Nonlinear current-voltage curves of gold quantum point contacts" [Appl. Phys. Lett. 87, 103104 (2005)]
In a recent Letter [Appl. Phys. Lett. 87, 103104 (2005)], Yoshida et al.
report that nonlinearities in current-voltage curves of gold quantum point
contacts occur as a result of a shortening of the distance between electrodes
at finite bias, presumably due to thermal expansion. For short wires, the
electrode displacement induces a thickening of the wire, as well as
nonlinearities of the IV curve, while the radius of long wires is left
unchanged, thus resulting in a linear IV curve. We argue here that electron
shell effects, which favor wires with certain "magic radii," prevent the
thickening of long wires under compression, but have little effect on wires
below a critical length.Comment: Version accepted for publication in Applied Physics Letter
Introduction to papers on astrostatistics
We are pleased to present a Special Section on Statistics and Astronomy in
this issue of the The Annals of Applied Statistics. Astronomy is an
observational rather than experimental science; as a result, astronomical data
sets both small and large present particularly challenging problems to analysts
who must make the best of whatever the sky offers their instruments. The
resulting statistical problems have enormous diversity. In one problem, one may
have to carefully quantify uncertainty in a hard-won, sparse data set; in
another, the sheer volume of data may forbid a formally optimal analysis,
requiring judicious balancing of model sophistication, approximations, and
clever algorithms. Often the data bear a complex relationship to the underlying
phenomenon producing them, much in the manner of inverse problems.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS234 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Percolation in the Sherrington-Kirkpatrick Spin Glass
We present extended versions and give detailed proofs of results concerning
percolation (using various sets of two-replica bond occupation variables) in
Sherrington-Kirkpatrick spin glasses (with zero external field) that were first
given in an earlier paper by the same authors. We also explain how
ultrametricity is manifested by the densities of large percolating clusters.
Our main theorems concern the connection between these densities and the usual
spin overlap distribution. Their corollaries are that the ordered spin glass
phase is characterized by a unique percolating cluster of maximal density
(normally coexisting with a second cluster of nonzero but lower density). The
proofs involve comparison inequalities between SK multireplica bond occupation
variables and the independent variables of standard Erdos-Renyi random graphs.Comment: 18 page
Fluctuational Instabilities of Alkali and Noble Metal Nanowires
We introduce a continuum approach to studying the lifetimes of monovalent
metal nanowires. By modelling the thermal fluctuations of cylindrical nanowires
through the use of stochastic Ginzburg-Landau classical field theories, we
construct a self-consistent approach to the fluctuation-induced `necking' of
nanowires. Our theory provides quantitative estimates of the lifetimes for
alkali metal nanowires in the conductance range 10 < G/G_0 < 100 (where
G_0=2e^2/h is the conductance quantum), and allows us to account for
qualitative differences in the conductance histograms of alkali vs. noble metal
nanowires
Nature vs. Nurture: Predictability in Low-Temperature Ising Dynamics
Consider a dynamical many-body system with a random initial state
subsequently evolving through stochastic dynamics. What is the relative
importance of the initial state ("nature") vs. the realization of the
stochastic dynamics ("nurture") in predicting the final state? We examined this
question for the two-dimensional Ising ferromagnet following an initial deep
quench from to . We performed Monte Carlo studies on the
overlap between "identical twins" raised in independent dynamical environments,
up to size . Our results suggest an overlap decaying with time as
with ; the same exponent holds for a
quench to low but nonzero temperature. This "heritability exponent" may equal
the persistence exponent for the 2D Ising ferromagnet, but the two differ more
generally.Comment: 5 pages, 3 figures; new version includes results for nonzero
temperatur
Theory of metastability in simple metal nanowires
Thermally induced conductance jumps of metal nanowires are modeled using
stochastic Ginzburg-Landau field theories. Changes in radius are predicted to
occur via the nucleation of surface kinks at the wire ends, consistent with
recent electron microscopy studies. The activation rate displays nontrivial
dependence on nanowire length, and undergoes first- or second-order-like
transitions as a function of length. The activation barriers of the most stable
structures are predicted to be universal, i.e., independent of the radius of
the wire, and proportional to the square root of the surface tension. The
reduction of the activation barrier under strain is also determined.Comment: 5 pages, 3 figure
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