16,618 research outputs found
Analysis of pressurized and axially loaded orthotropic multicell tanks
Nondimensional stress resultants and displacements for multicell tanks of orthotropic construction loaded by internal pressure and axial compressio
Spatial and Temporal Relationships Between Forest Bird Declines and Prevalence of the Hemlock Woolly Adelgid in the Northeastern United States
The eastern hemlock (Tsuga canadensis) is a vital foundation tree species throughout the eastern United States, providing essential structural diversity and habitat for more than 120 different animal species. Within the past few decades, T. canadensis has undergone significant declines that are largely associated with the hemlock woolly adelgid (HWA; Adelges tsugae), an exotic, aphid-like insect native to East Asia. From the 1970s to present day, the HWA has spread throughout southern New England, large portions of the Mid-Atlantic region, and parts of Tennessee and the Carolinas. Research has shown that loss of the eastern hemlock is drastically altering forest community structures, potentially impacting a wide variety of forest fauna, including avian populations strongly associated with hemlock forests. Here we present research investigating the correlation between HWA prevalence and recent declines of hemlock-associated forest birds in the Eastern US. We analyzed bird population trends data from the North American Breeding Bird Survey (BBS), US Forest Service HWA data, and land cover data to analyze the population trends of hemlock-associated and forest generalist species in association with the arrival of HWA, taking hemlock density into account. We found a significant correlation between the timing of HWA arrival and declines of conifer forest specialist birds. The Black-throated Green Warbler and the Blue-headed Vireo exhibited significant decline along survey routes after HWA arrival. Populations of some forest generalists (Tufted Titmouse, White-Breasted Nuthatch) were unaffected and continued to increase linearly, while others (Red-Eyed Vireo, Ovenbird) showed minor decrease in population
Effect of psychotropic drugs on gastric ulcers induced by immobilization: Increased protective effect of amitriptyline caused by chlordiazepoxide
Amitriptyline, but not chlordiazepoxide, protects rats from the occurrence of gastric erosions and ulcers following immobilization. When, however, chlordiazepoxide is given together with amitriptyline the protective effect of the latter is markedly increased
Online Local Learning via Semidefinite Programming
In many online learning problems we are interested in predicting local
information about some universe of items. For example, we may want to know
whether two items are in the same cluster rather than computing an assignment
of items to clusters; we may want to know which of two teams will win a game
rather than computing a ranking of teams. Although finding the optimal
clustering or ranking is typically intractable, it may be possible to predict
the relationships between items as well as if you could solve the global
optimization problem exactly.
Formally, we consider an online learning problem in which a learner
repeatedly guesses a pair of labels (l(x), l(y)) and receives an adversarial
payoff depending on those labels. The learner's goal is to receive a payoff
nearly as good as the best fixed labeling of the items. We show that a simple
algorithm based on semidefinite programming can obtain asymptotically optimal
regret in the case where the number of possible labels is O(1), resolving an
open problem posed by Hazan, Kale, and Shalev-Schwartz. Our main technical
contribution is a novel use and analysis of the log determinant regularizer,
exploiting the observation that log det(A + I) upper bounds the entropy of any
distribution with covariance matrix A.Comment: 10 page
The role of the Polyakov loop in finite density QCD
We study the behavior of the fermion determinant at finite temperature and
chemical potential, as a function of the Polyakov loop. The phase of the
determinant is correlated with the imaginary part of the Polyakov loop. This
correlation and its consequences are considered in static QCD, in a toy model
of free quarks in a constant background, and in simulations constraining
the imaginary part of the Polyakov loop to zero.Comment: 11 pages, 8 Postscript figures, Minor changes, quality of figures
improve
Ion observations from geosynchronous orbit as a proxy for ion cyclotron wave growth during storm times
[1] There is still much to be understood about the processes contributing to relativistic electron enhancements and losses in the radiation belts. Wave particle interactions with both whistler and electromagnetic ion cyclotron (EMIC) waves may precipitate or accelerate these electrons. This study examines the relation between EMIC waves and resulting relativistic electron flux levels after geomagnetic storms. A proxy for enhanced EMIC waves is developed using Los Alamos National Laboratory Magnetospheric Plasma Analyzer plasma data from geosynchronous orbit in conjunction with linear theory. In a statistical study using superposed epoch analysis, it is found that for storms resulting in net relativistic electron losses, there is a greater occurrence of enhanced EMIC waves. This is consistent with the hypothesis that EMIC waves are a primary mechanism for the scattering of relativistic electrons and thus cause losses of such particles from the magnetosphere
Coffin Soul Portals of the Female Xunren in Tomb of Marquis Yi of Zeng
There is a significant void in scholarship concerning the Tomb of Marquis Yi of Zeng’s (Zeng Hou Yi), Leigudun M1, Suizhou, Hubei Province, dated to 433 BCE during the Eastern Zhou Dynasty (770-256 BCE) of Bronze Age China, specifically on the lacquer coffins of the female xunren. There is extensive research dedicated to its well-preserved ritual bronze vessels, lacquer wares, and musical instruments, but this tomb is not known for the lacquer designs of portals present on twelve of the twenty-one female companion’s coffins. In this paper, I argue the xunren coffin designs in tomb Leigudun M1 of Zeng Hou Yi are fundamental to uncovering the tomb’s social hierarchy and its function in the afterlife through the presence of portal designs. To begin, I consider archaeological data on the lacquer coffins of the xunren, such as placement and grave goods, and correlate this to lacquer design complexity and portal design on the women’s coffins. I identified parallels between Leigudun M1 and comparable tombs containing burials for the xunren in large quantities that indicate an organized afterlife based on social status. Lastly, I address cosmology and contemporary literature on the afterlife because it illustrates the tradition of hierarchy, movement, and value of souls in the afterlife. By carefully examining the lacquer coffin designs, this study sheds new light on the meaning and value of these coffin soul portals and their relationship to the women and Marquis Yi in the afterlife
Brane Supersymmetry Breaking
We show how to construct chiral tachyon-free perturbative orientifold models,
where supersymmetry is broken at the string scale on a collection of branes
while, to lowest order, the bulk and the other branes are supersymmetric. In
higher orders, supersymmetry breaking is mediated to the remaining sectors, but
is suppressed by the size of the transverse space or by the distance from the
brane where supersymmetry breaking primarily occurred. This setting is of
interest for orbifold models with discrete torsion, and is of direct relevance
for low-scale string models. It can guarantee the stability of the gauge
hierarchy against gravitational radiative corrections, allowing an almost exact
supergravity a millimeter away from a non-supersymmetric world.Comment: 15 pages, LaTe
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