116,636 research outputs found
Seasonal Occurrence of Pine Root Collar Weevil, \u3ci\u3eHylobius Radicis\u3c/i\u3e (Coleoptera: Curculionidae), in Red Pine Stands Undergoing Decline
A trapping scheme was devised for sampling the pine root collar weevil, Hylobius radicis, in mature red pine plantations in Wisconsin. Adult weevils were trapped throughout the 1986 field season, and the method appears sensitive enough to discern temporal and spatial trends. The number of weevils caught was higher in stands symptomatic of the general condition currently labelled Red Pine Decline and Mortality. In some stands there was a strong tendency for trap catches to be particularly high near certain trees. Seasonal trends and sex ratios were compared with published reports of H. radicis activity in Michigan
Strongly Coupled Chameleon Fields: New Horizons in Scalar Field Theory
We show that as a result of non-linear self-interactions, scalar field
theories that couple to matter much more strongly than gravity are not only
viable but could well be detected by a number of future experiments, provided
these are properly designed to do so.Comment: 4 pages, 3 figs. Typos corrected. Comments added. Phys. Rev. Lett. in
prin
Coping with loss: cell adaptation to cytoskeleton disruption
Unravelling the role of cytoskeleton regulators may be complicated by adaptations to experimental manipulations. In this issue of Developmental Cell, Cerikan et al. (2016) reveal how acute effects of DOCK6 RhoGEF depletion on RAC1 and CDC42 activation are reversed over time by compensatory mechanisms that re-establish cellular homeostasis
Within-Generation Morality of the Jack Pine Tip Beetle, \u3ci\u3eConophthorus Banksianae\u3c/i\u3e McPherson, in Michigan
(excerpt)
The jack pine tip beetle (Conophthorus banksianae McPherson) is a shoot-infesting scolytid hat primarily attacks jack pine (Pinus banksiana Lamb.) in Michigan. The insect was previously thought to be a variant of C. resinosae Hopkins, which attacks cones and shoot tips of red pine. McPherson described C. banksianae as a new species, following life cycle and behavioral studies (McPherson, Wilson, and Stehr 1970; McPherson, Stehr, and Wilson 1970). Separating them by morphological features has been unsuccessful (Herdy 1963)
Multi-level Monte Carlo for continuous time Markov chains, with applications in biochemical kinetics
We show how to extend a recently proposed multi-level Monte Carlo approach to
the continuous time Markov chain setting, thereby greatly lowering the
computational complexity needed to compute expected values of functions of the
state of the system to a specified accuracy. The extension is non-trivial,
exploiting a coupling of the requisite processes that is easy to simulate while
providing a small variance for the estimator. Further, and in a stark departure
from other implementations of multi-level Monte Carlo, we show how to produce
an unbiased estimator that is significantly less computationally expensive than
the usual unbiased estimator arising from exact algorithms in conjunction with
crude Monte Carlo. We thereby dramatically improve, in a quantifiable manner,
the basic computational complexity of current approaches that have many names
and variants across the scientific literature, including the
Bortz-Kalos-Lebowitz algorithm, discrete event simulation, dynamic Monte Carlo,
kinetic Monte Carlo, the n-fold way, the next reaction method,the
residence-time algorithm, the stochastic simulation algorithm, Gillespie's
algorithm, and tau-leaping. The new algorithm applies generically, but we also
give an example where the coupling idea alone, even without a multi-level
discretization, can be used to improve efficiency by exploiting system
structure. Stochastically modeled chemical reaction networks provide a very
important application for this work. Hence, we use this context for our
notation, terminology, natural scalings, and computational examples.Comment: Improved description of the constants in statement of Theorem
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