61,513 research outputs found
Additions and Corrections to the Stoneflies (Plecoptera) of Iowa, U.S.A.
(exerpt)
Until recently, Iowa’s stonefly fauna was poorly documented. Heimdal et al. (2004) published a comprehensive report on stonefly distributions within the state, reporting seven families and 43 species. Five species, Allocapnia pygmaea (Burmeister) (Capiniidae), Leuctra tenuis (Pictet) (Leuctridae), Amphinemura linda (Ricker) (Nemouridae), Nemoura trispinosa Claassen (Nemouridae), and Soyedina vallicularia (Wu) (Nemouridae), were recommended for state protection because of their limited distribution within Iowa. Four species, Amphinemura delosa (Ricker), Isogenoides doratus (Frison) (Perlodidae), I. krumholzi (Ricker), and I. varians (Walsh), had limited distributions, but were not listed because their observed habitat preferences appeared common or were difficult to sample and poorly collected. From 2004 to 2006, fifteen county, state, and federal parks and preserves in east and northeast Iowa were sampled during the spring and summer in an effort to find additional locations for these nine species. The surveys yielded new distributional data for five species, including two new state records, and one species deletion, updating the total number of species recorded from Iowa to 44. A discussion for these records and corrections is presented below. Material collected from these surveys was deposited in the University of Iowa Hygienic Laboratory Collection (UHL) and the Illinois Natural History Survey Insect Collection (INHS)
Statistical analysis of network data and evolution on GPUs: High-performance statistical computing
Network analysis typically involves as set of repetitive tasks that are particularly amenable to poor-man's parallelization. This is therefore an ideal application are for GPU architectures, which help to alleviate the tedium inherent to statistically sound analysis of network data. Here we will illustrate the use of GPUs in a range of applications, which include percolation processes on networks, the evolution of protein-protein interaction networks, and the fusion of different types of biomedical and disease data in the context of molecular interaction networks. We will pay particular attention to the numerical performance of different routines that are frequently invoked in network analysis problems. We conclude with a review over recent developments in the generation of random numbers that address the specific requirements posed by GPUs and high-performance computing needs
Explaining the Duration of Exchange-Rate Pegs
This paper is a theoretical and empirical investigation into the duration of exchange-rate pegs. The theoretical model considers a policy-maker who must trade off the economic costs of real exchange- rate misalignment against the political cost of realignment. The optimal time to spend on a peg is derived and factors that influence peg duration are identified. The predictions of the model are tested using logit analysis with a data set of exchange-rate pegs for sixteen Latin American countries and Jamaica during the 1957-1991 period. We find that the real exchange rate is a significant determinant of the likelihood of a devaluation. Structural variables, such as the openness of the economy and its geographical trade concentration, also significantly affect the likelihood of a devaluation. Finally, political events that change the political cost of realignment, such as regular and irregular executive transfers, are empirically important determinants of the likelihood of a devaluation.
The effects of stabilizing and destabilizing longitudinal curvature on the structure of turbulent, two-stream mixing layers
The construction and development of the multi-component traversing system and associated control hardware and software are presented. A hydrogen bubble/laser sheet flow visualization technique was developed to visually study the characteristics of the mixing layers. With this technique large-scale rollers arising from the Taylor-Gortler instability and its interaction with the primary Kelvin-Helmholtz structures can be studied
Testing for a pure state with local operations and classical communication
We examine the problem of using local operations and classical communication
(LOCC) to distinguish a known pure state from an unknown (possibly mixed)
state, bounding the error probability from above and below. We study the
asymptotic rate of detecting multiple copies of the pure state and show that,
if the overlap of the two states is great enough, then they can be
distinguished asymptotically as well with LOCC as with global measurements;
otherwise, the maximal Schmidt coefficient of the pure state is sufficient to
determine the asymptotic error rate.Comment: 11 pages, 2 figures. Published version with small revisions and
expanded title
A Physical Theory of the Competition that Allows HIV to Escape from the Immune System
Competition within the immune system may degrade immune control of viral
infections. We formalize the evolution that occurs in both HIV-1 and the immune
system quasispecies. Inclusion of competition in the immune system leads to a
novel balance between the immune response and HIV-1, in which the eventual
outcome is HIV-1 escape rather than control. The analytical model reproduces
the three stages of HIV-1 infection. We propose a vaccine regimen that may be
able to reduce competition between T cells, potentially eliminating the third
stage of HIV-1.Comment: 5 pages, 2 figures, to appear in Phys. Rev. Let
Irreversible photon transfer in an ensemble of -type atoms and photon diode
We show that a pair of quantized cavity modes interacting with a spectrally
broadened ensemble of Lambda-type atoms is analogous to an ensemble of two
level systems coupled to a bosonic reservoir. This provides the possibility for
an irreversible photon transfer between photon modes. The density of states as
well as the quantum state of the reservoir can be engineered allowing the
observation of effects such as the quantum Zeno- and anti-Zeno effect, the
destructive interference of decay channels and the decay in a squeezed vacuum.
As a particular application we discuss a photon diode, i.e. a device which
directs a single photon from anyone of two input ports to a common output port.Comment: 5 pages, 2 figure
A Versatile Pseudo-Random Noise Generator
A detailed design is presented for a digital pseudo-random noise generator. The instrument is built with standard integrated circuits. It produces both binary noise (pseudo-random binary sequences) and white Gaussian noise of variable bandwidth. By setting front panel switches to match tabulated octal codes, one may select a vast number of independent noise programs
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