2,413 research outputs found

    Pictorial Guide to the Groupers (Teleostei: Serranidae) of the Western North Atlantic

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    This guide was developed to assist with the identification of western North Atlantic grouper species of the genera Alphestes, Cephalopholis, Dermatolepis, Epinephelus, Gonioplectrus, Mycteroperca, and Paranthias. The primary purpose for assembling the guide is for use with projects that deploy underwater video camera systems. The most vital source of information used to develop the guide was an archive of underwater video footage recorded during fishery projects. These video tapes contain 348 hours of survey activity and are maintained at the National Marine Fisheries Service (NMFS), Pascagoula, Mississippi. This footage spans several years (1980-92) and was recorded under a wide variety of conditions depicting diverse habitats from areas of the western North Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. Published references were used as sources of information for those species not recorded on video footage during NMFS projects. These references were also used to augment information collected from video footage to provide broader and more complete descriptions. The pictorial guide presents information for all 25 grouper species reported to occur in the western North Atlantic. Species accounts provide descriptive text and illustrations depicting documented phases for the various groupers. In addition, species separation sheets based on important identification features were constructed to further assist with species identification. A meristic table provides information for specimens captured in conjunction with videoassisted fishery surveys. A computerized version enables guide users to amend, revise, update, or customize the guide as new observations and information become available. (PDF file contains 52 pages.

    Partial-Transfer Absorption Imaging: A versatile technique for optimal imaging of ultracold gases

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    Partial-transfer absorption imaging is a tool that enables optimal imaging of atomic clouds for a wide range of optical depths. In contrast to standard absorption imaging, the technique can be minimally-destructive and can be used to obtain multiple successive images of the same sample. The technique involves transferring a small fraction of the sample from an initial internal atomic state to an auxiliary state and subsequently imaging that fraction absorptively on a cycling transition. The atoms remaining in the initial state are essentially unaffected. We demonstrate the technique, discuss its applicability, and compare its performance as a minimally-destructive technique to that of phase-contrast imaging.Comment: 10 pages, 5 figures, submitted to Review of Scientific Instrument

    Physical Condition, Sex, and Age-Class of Eastern Red-Backed Salamanders ( Plethodon cinereus

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    Nonforested habitats such as open fields and pastures have been considered unsuitable for desiccation-prone woodland salamanders such as the Eastern Red-backed Salamander (Plethodon cinereus). Recent research has suggested that Plethodon cinereus may not only disperse across but also reside within open habitats including fields, meadows, and pastures. However, presence and high densities of P. cinereus within agriculturally disturbed habitats may be misleading if these populations exhibit atypical demographic characteristics or decreased physical condition relative to forest populations. We surveyed artificial cover boards from 2004-2005 to compare physical condition, sex ratios, and age-class structure of P. cinereus among woodland, woodland-meadow edge, silvopasture, and meadow sites in the central Appalachian Mountains of southern West Virginia. Physical condition of salamanders was not significantly different among the four habitats. Furthermore, adult sex ratios of P. cinereus typically were not significantly different from 1 : 1 and were similar between forested and non-forested sites, although populations within silvopastures were biased towards females. However, adult salamanders were significantly more abundant than juveniles in all habitat types, with differences most pronounced within meadow habitats. Our study indicates that relatively small, non-forested habitats such as silvopastures and meadows may not adversely affect the overall physical condition or sex ratios of Plethodon cinereus. However, the paucity of juveniles within disturbed meadows indicates that these agriculturally modified habitats may negatively impact reproduction or that immature salamanders are at a physiological or competitive disadvantage in comparison to adults, particularly when surface cover is limited

    Anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft versus allograft in young patients

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    Objectives: Traditionally, bone-patella tendon-bone (BTB) autograft has been the gold standard graft choice for younger, athletic patients requiring ACL reconstruction. However, donor site morbidity, post-operative patella fracture, and increased operative time have led many surgeons to choose BTB allograft for their reconstructions. Opponents of allografts feel that slower healing time, higher rate of graft failure, and potential for disease transmission makes them undesirable graft choices in athletic patients. The purpose of this study is to evaluate the clinical outcomes, both subjective and objective, of young patients that who have undergone either BTB autograft or allograft reconstructions with a minimum of 2-year follow-up. Methods: One hundred and twenty patients (60 autograft, 60 allograft), age 25 and below at time of surgery, were contacted after being retrospectively identified as patients having an ACL reconstruction with either a BTB allograft or autograft by one senior surgeon. Patients were administered the Lysholm Knee Scoring Scale and IKDC Subjective Knee Evaluation questionnaires. Fifty (25 BTB autograft and 25 BTB allograft) of the 120 returned for physical examination as well as completion of a single leg hop test and laxity evaluation using a KT-1000 arthrometer evaluation. Of the 120 patients contacted, there were a total of 7 failures (5.8%) requiring revision, 6 in the allograft group (86%) and 1 in the autograft group (14%). Results: The average Lysholm scores were 89.0 and 89.56 and the average IKDC scores were 90.8 and 92.1 in the autograft and allograft groups respectively. The differences in the Lysholm scores and the IKDC scores were not significant. The single leg hop and KT-1000 scores were also not significantly different. One autograft patient had a minor motion deficit. Three allograft patients had a grade 1 Lachman and pivot glide. One autograft patient and two allograft patients had mild patellafemoral crepitus. There was no significant difference in anterior knee pain between the two groups Conclusion: There is no significant difference in patient-rated outcome between ACL reconstructions using BTB autografts versus allografts. However, the overall study group did reveal an increased failure rate requiring revision in the allograft group. © The Author(s) 2015

    Physical Processes Dictate Early Biogeochemical Dynamics of Soil Pyrogenic Organic Matter in a Subtropical Forest Ecosystem

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    Quantifying links between pyOM dynamics, environmental factors and processes is central to predicting ecosystem function and response to future perturbations. In this study, changes in carbon (TC), nitrogen (TN), pH, and relative recalcitrance (R50) for pineand cordgrass-derived pyOM were measured at 3–6 weeks intervals throughout the first year of burial in the soil. Objectives were to (1) identify key environmental factors and processes driving early-stage pyOM dynamics, and (2) develop quantitative relationships between environmental factors and observed changes in pyOM properties. The study was conducted in sandy soils of a forested ecosystem within the Longleaf pine range of the United States with a focus on links between changes in pyOM properties, fire history (FH), cumulative precipitation (Pcum), average temperature (Tavg) and soil residence time (SRT). Pcum, SRT and Tavg were the main factors controlling TC and TN accounting for 77–91% and 64–96% of their respective variability. Fire history, along with Pcum, SRT and Tavg, exhibited significant controlling effects on pyOM pH and R50—accounting for 48–91% and 88–93% of respective variability. Volatilization of volatiles and leaching of water-soluble components (in summer) and the sorption of exogenous organic matter (fall through spring) were most plausibly controlling pyOM dynamics in this study. Overall, our results point to climatic and land management factors and physicochemical process as the main drivers of pyOM dynamics in the pine ecosystems of the Southeastern U

    Carbon Free Boston: Technical Summary

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    Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Buildings Technical Report; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: This technical summary is intended to argument the rest of the Carbon Free Boston technical reports that seek to achieve this goal of deep mitigation. This document provides below: a rationale for carbon neutrality, a high level description of Carbon Free Boston’s analytical approach; a summary of crosssector strategies; a high level analysis of air quality impacts; and, a brief analysis of off-road and street light emissions.Published versio

    Electrical properties of Bi-implanted amorphous chalcogenide films

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    The impact of Bi implantation on the conductivity and the thermopower of amorphous chalcogenide films is investigated. Incorporation of Bi in Ge-Sb-Te and GeTe results in enhanced conductivity. The negative Seebeck coefficient confirms onset of the electron conductivity in GeTe implanted with Bi at a dose of 2x1016 cm-2. The enhanced conductivity is accompanied by defect accumulation in the films upon implantation as is inferred by using analysis of the space-charge limited current. The results indicate that native coordination defects in lone-pair semiconductors can be deactivated by means of ion implantation, and higher conductivity of the films stems from additional electrically active defects created by implantation of bismuth.Comment: This is an extended version of the results presented in Proc. SPIE 8982, 898213 (2014

    Biogenic methane in shale gas and coal bed methane : a review of current knowledge and gaps

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    Biogenic CH4 generation has been observed in many shallow, low temperature shale gas basins and coal seams. The depletion of conventional resources and the increasing demand of natural gas for human consumption have spurred the development of so-called unconventional gas resources such as shale gas (SG) and coal-bed methane (CBM). Such unconventional systems represent the opportunity for the stimulation of biogenic CH4 generation. Biogenic CH4 in shale and coal is produced by anaerobic biodegradation of organic matter (OM): methanogenic Archaea represent only the final step of biogenic CH4 generation. Several communities of microorganisms are involved in the initial breakdown of complex geopolymers and the production of intermediate compounds used by methanogens. There are several key knowledge gaps on biogenic CH4 production in unconventional gas systems, such as the exact fraction of bioavailable OM, the microbial communities involved and how they can be stimulated to enhance microbial methanogenesis. Progress on biodegradation studies, isotopic signatures, as well as DNA analyses and proteomics could help unravel interactions within the syntrophic community involved in the methanogenic biodegradation of OM. Questions also remain regarding the environmental impact of unconventional gas production, such as water quality and the mobility of toxic metals and radionuclides. The answers to these questions might have implications for both recovery practices and a sustainable development of unconventional resources. This review summarises the current knowledge regarding biogenic CH4 in SG and CBM: from the nature of the rocks to the producing microbial community and the indicators of biogenic CH4, illustrating how these two environments show remarkably similar opportunities for the stimulation of biogenic CH4 generation
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