Status Survey of the Arkansas Endemic Crayfish, Fallicambarus gilpini Hobbs and Robinson

Fieldwork was conducted during 2002-2003 on the rare, Arkansas endemic crayfish, Fallicambarus gilpini Hobbs and Robison. Collections at 87 localities revealed this crayfish at 8 sites, all located in southeastern Arkansas in Jefferson and Cleveland counties which significantly expands its known range. Fallicambarus gilpini was generally found inhabiting roadside ditches and areas of standing water where it was always taken from upslope areas away from the static water. A sex ratio of 1:1.3 males to females was determined for this species. Ovigerous females were collected from burrows on 20 March 2003. A conservation status of threatened is recommended for this crayfish species

From real materials to model Hamiltonians with density matrix downfolding

Due to advances in computer hardware and new algorithms, it is now possible to perform highly accurate many-body simulations of realistic materials with all their intrinsic complications. The success of these simulations leaves us with a conundrum: how do we extract useful physical models and insight from these simulations? In this article, we present a formal theory of downfolding--extracting an effective Hamiltonian from first-principles calculations. The theory maps the downfolding problem into fitting information derived from wave functions sampled from a low-energy subspace of the full Hilbert space. Since this fitting process most commonly uses reduced density matrices, we term it density matrix downfolding (DMD).Comment: 24 pages, 12 figures; Huihuo Zheng and Hitesh J. Changlani contributed equally to this wor

Status and Distribution of the Arkansas Darter (Etheostoma cragini) in Arkansas

The Arkansas darter, Etheostoma cragini, has an extremely limited distribution in Arkansas and is designated as a andidate for listing under the Endangered Species Act. It was first discovered in the state in 1979 in Wilson Spring near Fayetteville and has since been found in4 additional headwater streams in Benton and Washington counties prior to this study. A study in 1997 (bund the species in3 of the 5 historic streams, but one stream yielded only a single individual. This study sought to reassess the status of the 5 historically known populations and sample additional spring-run habitats in the Arkansas River basin in these 2 counties. Spring branch habitats were identified using USGS topographic maps and available GIS coverages. Surveys targeting E. cragini were conducted at 75 sites providing abroad coverage of the basin and including intense searches in the vicinity of historic sites. E. cragini were encountered in15 stream segments, concentrated in4 areas within the Illinois River basin. All segments supported numerous E. cragini and fell within a 2 km radius of historic sites. Each segment was broadly surveyed to delineate the extent of occupied stream length, which ranged from 10 to 1,645 m. Based on this survey the total occupied stream length for E. cragini in Arkansas was determined to be 5,676 m. These segments include three historic locations and 5 disjunct stream reaches. While the presence of E. cragini in Arkansas is persisting, rapid urban development in northwest Arkansas raises concern for some populations

Status and Distribution of the Gapped Ringed Crayfish, Orconectes neglectus chaenodactylus, in Arkansas

Orconectes neglectus chaenodactylus, the gapped ringed crayfish, is an uncommon and poorly-known, stream-dwelling crayfish that is endemic to the central White River basin of Arkansas and Missouri. This study surveyed a semi-random selection of stream sites in the Arkansas portion of this range in order to characterize the crayfish communities and evaluate the status of O. n. chaenodactylus in Arkansas. Collections of a total of 1,107 individual crayfish specimens were made at 45 sites, including 497 O. n. chaenodactylus from 21 sites. Orconectes punctimanus was the crayfish species most commonly associated with O. n. chaenodactylus, occurring at 71% of sites occupied by O. n. chaenodactylus. Orconectes n. chaenodactylus was found in streams not significantly different from the median characteristics of streams sampled in the study. It is our opinion that O. n. chaenodactylus is uncommon in Arkansas, and of only moderate concern due to its limited distribution in the state

Mixing of Supersonic Streams

The Strutjet approach to Rocket Based Combined Cycle (RBCC) propulsion depends upon fuel-rich flows from the rocket nozzles and turbine exhaust products mixing with the ingested air for successful operation in the ramjet and scramjet modes. A model of the Strutjet device has been built and is undergoing test to investigate the mixing of the streams as a function of distance from the Strutjet exit plane. Initial cold flow testing of the model is underway to determine both, the behavior of the ingested air in the duct and to validate the mixing diagnostics. During the tests, each of the two rocket nozzles ejected up to two pounds mass per second into the 13.6 square inch duct. The tests showed that the mass flow of the rockets was great enough to cause the entrained air to go sonic at the strut, which is the location of the rocket nozzles. More tests are necessary to determine whether the entrained air chokes due to the reduction in the area of the duct at the strut (a physical choke), or because of the addition of mass inside the duct at the nozzle exit (a Fabri choke). The initial tests of the mixing diagnostics are showing promise

Effect of the Synthetic Bile Salt Analog CamSA on the Hamster Model of Clostridium difficile Infection

Clostridium difficile infection (CDI) is the leading cause of antibiotic-associated diarrhea and has gained worldwide notoriety due to emerging hypervirulent strains and the high incidence of recurrence. We previously reported protection of mice from CDI using the antigerminant bile salt analog CamSA. Here we describe the effects of CamSA in the hamster model of CDI. CamSA treatment of hamsters showed no toxicity and did not affect the richness or diversity of gut microbiota; however, minor changes in community composition were observed. Treatment of C. difficile-challenged hamsters with CamSA doubled the mean time to death, compared to control hamsters. However, CamSA alone was insufficient to prevent CDI in hamsters. CamSA in conjunction with suboptimal concentrations of vancomycin led to complete protection from CDI in 70% of animals. Protected animals remained disease-free at least 30 days postchallenge and showed no signs of colonic tissue damage. In a delayed-treatment model of hamster CDI, CamSA was unable to prevent infection signs and death. These data support a putative model in which CamSA reduces the number of germinating C. difficile spores but does not keep all of the spores from germinating. Vancomycin halts division of any vegetative cells that are able to grow from spores that escape CamSA

Restoring Native Grasslands

4 pp., 5 color photos, 1 map, 3 graphsMuch of Texas' native grasslands has been converted to improved pastures and cropland, neither of which is suitable for wildlife habitat. Now, many landowners are interested in restoring native grasses because they are cheaper to produce for forage than are improved pastures and they also encourage wildlife. This publication explains how to carry out such restoration and the results to expect

An evaluation of Bradfordizing effects

The purpose of this paper is to apply and evaluate the bibliometric method Bradfordizing for information retrieval (IR) experiments. Bradfordizing is used for generating core document sets for subject-specific questions and to reorder result sets from distributed searches. The method will be applied and tested in a controlled scenario of scientific literature databases from social and political sciences, economics, psychology and medical science (SOLIS, SoLit, USB Köln Opac, CSA Sociological Abstracts, World Affairs Online, Psyndex and Medline) and 164 standardized topics. An evaluation of the method and its effects is carried out in two laboratory-based information retrieval experiments (CLEF and KoMoHe) using a controlled document corpus and human relevance assessments. The results show that Bradfordizing is a very robust method for re-ranking the main document types (journal articles and monographs) in today’s digital libraries (DL). The IR tests show that relevance distributions after re-ranking improve at a significant level if articles in the core are compared with articles in the succeeding zones. The items in the core are significantly more often assessed as relevant, than items in zone 2 (z2) or zone 3 (z3). The improvements between the zones are statistically significant based on the Wilcoxon signed-rank test and the paired T-Test