22 research outputs found

    AMPHIBIAN AND REPTILE COLONIZATION OF RECLAIMED COAL SPOIL GRASSLANDS

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    While habitat loss is a major driver of amphibian and reptile declines globally, a subset of post-industrial landscapes, reclaimed and restored, are creating habitat for these animals. In a previous work, we showed that amphibians and reptiles use reclaimed and restored grasslands. In the present work we quantify captures at drift-fence/pitfall trap arrays over two consecutive years and show that several species of amphibians are not only successfully reproducing but that juveniles are being recruited into the population. In particular, 15,844 amphibians and 334 reptiles representing 25 species (14 amphibians, 11 reptiles) were captured at drift fences in 2009 and 2010. Nine additional reptile species were found opportunistically while conducting other research activities at the study site. Out of a total of 8,064 metamorphosing juveniles we detected 126 malformations, a 1.6% rate. The major malformation types were limbs missing (amelia) or foreshortened (ectromely), eye discolorations, and digits foreshortened (ectrodactyly) or small (brachydactyly). Our data show that reclaimed, restored, and properly managed landscapes can support reproducing populations of amphibians and reptiles with low malformation rates, including species in decline across other portions of their range

    A viable superluminal hypothesis: Tachyon emission from orthopositronium

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    Tachyons are hypothetical particles that travel faster than the vacuum speed of light. Previous experiments have searched for, but have not found evidence of tachyons. Long-standing, anomalous measurements of the orthopositronium (o-Ps) decay rate are interpreted as evidence for two tachyons being occasionally emitted when o-Ps decays. Restricting the coupling of tachyon pairs to a single photon (no tachyon coupling to matter) yields a new theory where tachyons are only observed in o-Ps decay and not in the previous tachyon experiments. Combining the single photon coupling theory with all previous experiments predicts that these tachyons must deposit energy while traversing scintillator detectors. A new tachyon search experiment will use this energy loss prediction to attempt to find tachyons passing through the apparatus or set limits disproving the original o-Ps to tachyon hypothesis. Viewing an intense o-Ps source, a time-of-flight spectrometer uses the superluminal property of tachyons for identification. Several months of continuous data acquisition will be necessary to completely eliminate the o-Ps to tachyon hypothesis. © 2000 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87640/2/1119_1.pd

    Energy-dependent Ps-He momentum-transfer cross section at low energies

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    Positronium (Ps)-He scattering presents one of the few opportunities for both theory and experiment to tackle the fundamental interactions of Ps with ordinary matter. Below the dissociation energy of 6.8 eV, experimental and theoretical work has struggled to find agreement on the strength of this interaction as measured by the momentum-transfer cross section (Ïm). Here, we present work utilizing the Doppler broadening technique with an age-momentum correlation apparatus. This work demonstrates a strong energy dependence for this cross section at energies below 1 eV and is consistent with previous experimental results

    Thermalization of Positronium in Gases

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    The thermalization of positronium ( Ps) formed at a few eV in gases is investigated using timeresolved, Doppler broadening measurements of the annihilation photons. Magnetic quenching permits energy measurements about 40 ns after Ps is formed in H 2 , N 2 , He, Ne, Ar, isobutane, and neopentane. The thermalization rate is measured by changing the gas density, and a classical elastic scattering cross section and a Ps formation energy are determined. The impact of Ps thermalization on decay rate experiments using gases is also discussed. [S0031-9007(98) PACS numbers: 36.10. Dr, 34.50.Bw, 78.70.Bj Collisions between normal gas atoms and the exotic atom positronium (Ps, positron-electron bound state) are interesting and unique because Ps is so light relative to its target. Hence Ps, formed at typically a few eV in most gases, will thermalize very slowly if elastic scattering is the only available energy loss mechanism. In the elastic case, the fractional energy loss per collision is only of order m͞M ϳ 10 24 (m is the Ps mass, M is the atomic/molecular mass.) The low energy Ps-atom collision is also inherently quantum mechanical in nature since the de Broglie wavelength of Ps below 1 eV is greater than 9 Å, larger than the classical geometric atomic size. Moreover, it was recognized early [1] that cross section calculations must include the polarization/Van der Waals interaction and electron exchange. These features apparently complicate the calculations of cross sections, done presently including the exchange interaction for only oneand two-electron systems scattering Ps (H: [2]; H 2 : [3]; He: Positronium as a scattering probe offers a unique experimental advantage since its annihilation into two photons provides a mechanism for determining its velocity and hence the rate of thermalization and the momentum transfer cross section ͑s m ͒ for gas targets. Previous measurements of Ps thermalization in gases In this Letter, we report the measurement of Ps thermalization rates, formation energies, and momentum transfer cross sections in purely gaseous target using time-resolved Doppler Broadening Spectroscopy (DBS). In this complementary technique to ACAR, the Doppler broadening of the back-to-back annihilation photons observed in a single high-resolution Ge detector is a measure of the longitudinal momentum of the annihilating Ps. Timing information as well as DBS is derived from the Ge detector signal, enabling the direct correlation between age and energy of the Ps to be determined. The rate of thermalization and the average formation energy of Ps can then be determined. The gases used in this investigation include He, H 2 , and Ar for comparison to the theoretical calculations The thermalization rate of Ps in a noble gas was calculated 30 years ago by Sauder [14], under the assumption of classical elastic scattering, i.e., an energy-independent cross section for energy loss (momentum transfer) s m which was interpreted as the classical geometrical atomic cross section. If Ps is formed at only a few eV, below the 5.1 eV threshold for excitation of the Ps or the noble gas ͑.10 eV͒ and slow enough to avoid collisional dissociation, Sauder's elastic model may be appropriate. The Ps kinetic energy E͑t͒, as it asymptotically approaches thermal energy, E th , is given by where b is related to the average initial energy E 0 of Ps that can eventually thermalize: coth 2 b E 0 ͞E th . G is 0031-9007͞98͞80(17)͞3727(4)$15.0

    Virulence factors and antibiotic susceptibility in enterococci isolated from oral mucosal and deep infections

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    This study evaluates the presence of virulence factors and antibiotic susceptibility among enterococcal isolates from oral mucosal and deep infections. Forty-three enterococcal strains from oral mucosal lesions and 18 from deep infections were isolated from 830 samples that were sent during 2 years to Oral Microbiology, University of Gothenburg, for analysis. The 61 strains were identified by 16S rDNA, and characterized by the presence of the virulence genes efa A (endocarditis gene), gel E (gelatinase gene), ace (collagen binding antigen gene), asa (aggregation substance gene), cyl A (cytolysin activator gene) and esp (surface adhesin gene), tested for the production of bacteriocins and presence of plasmids. MIC determination was performed using the E-test method against the most commonly used antibiotics in dentistry, for example, penicillin V, amoxicillin and clindamycin. Vancomycin was included in order to detect vancomycin-resistant enterococci (VRE) strains. Sixty strains were identified as Enterococcus faecalis and one as Enterococcus faecium. All the virulence genes were detected in more than 93.3% (efa A and esp) of the E. faecalis strains, while the presence of phenotypic characteristics was much lower (gelatinase 10% and hemolysin 16.7%). Forty-six strains produced bacteriocins and one to six plasmids were detected in half of the isolates. Enterococcal strains from oral infections had a high virulence capacity, showed bacteriocin production and had numerous plasmids. They were generally susceptible to ampicillins but were resistant to clindamycin, commonly used in dentistry, and no VRE-strain was found

    The Social Structure of the Market for Force

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    Over the past two decades, governments have increasingly contracted private military and security companies (PMSCs) to support military operations in conflicts. However, many observers have argued that such companies are ‘greedy market actors’ or ‘reckless mercenaries’ and their level of performance very poor. A minority has defended them as security professionals. If market competition is present, the level of performance is high and positive contributions to the client’s military operation can be expected. However, neither PMSC opponents nor proponents can account for the variance in the level of performance in three crucial cases – Sierra Leone, Iraq, and Afghanistan. This article argues that different market structures explain this variance. At least three ideal configurations exist: collaborative, competitive, and rival structures. These structures influence the level of performance. PMSC performance levels are expected to decrease from the first configuration, being positive, to the last, being negative

    The Status of Crawfish Frogs (lithobates areolatus) in Indiana, and a Tool to Assess Populations

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    The conservation status of Crawfish Frogs (Lithobates areolatus) in Indiana has changed over the past several decades. Once described as being locally plentiful, declines led to the listing of Crawfish Frogs as a State Endangered Species in 1988. Several records for this species in Indiana are > 50 yrs old and have gone unconfirmed for several decades. However, recent surveys have confirmed the continued presence of Crawfish Frogs in parts of southern Indiana, redefining the perceived range of this species in the state. In an effort to increase survey efficiency in this species, I used automated recording systems and manual call survey techniques to examine the chorusing phenologies of Crawfish Frogs at two sites along the northern extent of their range. Detection probabilities were determined as they related to season and environmental variables and survey duration. I also examined the effect that distance from wetland and position (ground level vs. approximate human ear level) had on call detection in automated recording systems. Correlations between call rates (calls/min) and numbers of male Crawfish Frogs present were used to calculate population estimates at 10 uncensused sites. Detection probabilities were highest when the frogs were breeding and when air temperatures were ≥ 13° C. Initial detection of Crawfish Frogs most frequently occurred during the first five min of sampling. Calls on automated recording units lost resolution as distance from wetland increased, and calls recorded at all distances at human ear level were measurably louder (in decibels) except at the wetland edge. Population estimates at uncensused sites ranged from a low of four to a high of 48. Using call rates and numbers of male frogs present in wetlands, I present a “rapid assessment” tool that can be used to quickly calculate on-site estimates of Crawfish Frogs in field studies.Nathan J. EngbrechtLannoo, Michael J.(Indiana University)Gary S. CasperSteven L. LimaJohn O.WhitakerMaster of ScienceDepartment of BiologyCunningham Memorial library, Terre Haute,Indiana State University201005-18MastersTitle from document title page. Document formatted into pages: contains 90p.: ill. Includes bibliography, abstract and appendix

    Gastric remnant carcinoma: reevaluation of screening endoscopy.

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    A 67-year-old male presented with complaints of chronic postprandial pain in the epigastric region. The patient had undergone a vagotomy, antrectomy, and loop gastrojejunostomy for peptic ulcer disease 25 years prior. Abdominal computed tomography (CT) revealed markedly thickened walls of the gastric remnant with infiltration of the adjacent fat planes. An esophagogastroscopy demonstrated erythematous, friable remnant mucosa. Gastric biopsies revealed invasive adenocarcinoma. At laparotomy a large tumor mass involving the gastric remnant and the antecolic loop gastrojejunostomy was identified. Further exploration revealed a firm nodule in the left lobe of the liver and several small nodules on the diaphragm and the lesser omentum. Biopsies confirmed metastatic adenocarcinoma at all sites. Curative resection was abandoned. Gastric remnant carcinoma (GRC) typically presents more than 20 years after resection for peptic ulcer disease and has a history of poor survival rates. With increased use of diagnostic endoscopy, GRC has been detected at earlier stages. Recent cohort studies demonstrate that GRC has similar survival rates after stage stratification when compared with primary proximal gastric carcinoma. The increased incidence of GRC in later decades (\u3e20 years) after operation in conjunction with decreasing numbers of patients suggests that screening endoscopy should be considered on a 2- to 5-year basis in this population

    Distinct Preflowering Drought Tolerance Strategies of Sorghum bicolor Genotype RTx430 Revealed by Subcellular Protein Profiling

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    Drought is the largest stress affecting agricultural crops, resulting in substantial reductions in yield. Plant adaptation to water stress is a complex trait involving changes in hormone signaling, physiology, and morphology. Sorghum (Sorghum bicolor (L.) Moench) is a C4 cereal grass; it is an agricultural staple, and it is particularly drought-tolerant. To better understand drought adaptation strategies, we compared the cytosolic- and organelle-enriched protein profiles of leaves from two Sorghum bicolor genotypes, RTx430 and BTx642, with differing preflowering drought tolerances after 8 weeks of growth under water limitation in the field. In agreement with previous findings, we observed significant drought-induced changes in the abundance of multiple heat shock proteins and dehydrins in both genotypes. Interestingly, our data suggest a larger genotype-specific drought response in protein profiles of organelles, while cytosolic responses are largely similar between genotypes. Organelle-enriched proteins whose abundance significantly changed exclusively in the preflowering drought-tolerant genotype RTx430 upon drought stress suggest multiple mechanisms of drought tolerance. These include an RTx430-specific change in proteins associated with ABA metabolism and signal transduction, Rubisco activation, reactive oxygen species scavenging, flowering time regulation, and epicuticular wax production. We discuss the current understanding of these processes in relation to drought tolerance and their potential implications

    Mine Spoil Prairies Expand Critical Habitat for Endangered and Threatened Amphibian and Reptile Species

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    Coal extraction has been occurring in the Midwestern United States for over a century. Despite the pre-mining history of the landscape as woodlands, spent surface coalfields are often reclaimed to grasslands. We assessed amphibian and reptile species on a large tract of coal spoil prairie and found 13 species of amphibians (nine frog and four salamander species) and 19 species of reptiles (one lizard, five turtle, and 13 snake species). Two state-endangered and three state species of special concern were documented. The amphibian diversity at our study site was comparable to the diversity found at a large restored prairie situated 175 km north, within the historic prairie peninsula
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