494 research outputs found

    Herpetofaunal Inventories of the National Parks of South Florida and the Caribbean: Volume III. Big Cypress National Preserve

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    Amphibian declines and extinctions have been documented around the world, often in protected natural areas. Concern for this trend has prompted the U.S. Geological Survey and the National Park Service to document all species of amphibians that occur within U.S. National Parks and to search for any signs that amphibians may be declining. This study, an inventory of amphibian species in Big Cypress National Preserve, was conducted from 2002 to 2003. The goals of the project were to create a georeferenced inventory of amphibian species, use new analytical techniques to estimate proportion of sites occupied by each species, look for any signs of amphibian decline (missing species, disease, die-offs, and so forth.), and to establish a protocol that could be used for future monitoring efforts. Several sampling methods were used to accomplish these goals. Visual encounter surveys and anuran vocalization surveys were conducted in all habitats throughout the park to estimate the proportion of sites or proportion of area occupied (PAO) by each amphibian species in each habitat. Opportunistic collections, as well as limited drift fence data, were used to augment the visual encounter methods for highly aquatic or cryptic species. A total of 545 visits to 104 sites were conducted for standard sampling alone, and 2,358 individual amphibians and 374 reptiles were encountered. Data analysis was conducted in program PRESENCE to provide PAO estimates for each of the anuran species. All of the amphibian species historically found in Big Cypress National Preserve were detected during this project. At least one individual of each of the four salamander species was captured during sampling. Each of the anuran species in the preserve was adequately sampled using standard herpetological sampling methods, and PAO estimates were produced for each species of anuran by habitat. This information serves as an indicator of habitat associations of the species and relative abundance of sites occupied, but it will also be useful as a comparative baseline for future monitoring efforts. In addition to sampling for amphibians, all encounters with reptiles were documented. The sampling methods used for detecting amphibians are also appropriate for many reptile species. These reptile locations are included in this report, but the number of reptile observations was not sufficient to estimate PAO for reptile species. We encountered 35 of the 46 species of reptiles believed to be present in Big Cypress National Preserve during this study, and evidence exists of the presence of four other reptile species in the Preserve. This study found no evidence of amphibian decline in Big Cypress National Preserve. Although no evidence of decline was observed, several threats to amphibians were identified. Introduced species, especially the Cuban treefrog (Osteopilus septentrionalis), are predators and competitors with several native frog species. The recreational use of off-road vehicles has the potential to affect some amphibian populations, and a study on those potential impacts is currently underway. Also, interference by humans with the natural hydrologic cycle of south Florida has the potential to alter the amphibian community. Continued monitoring of the amphibian species in Big Cypress National Preserve is recommended. The methods used in this study were adequate to produce reliable estimates of the proportion of sites occupied by most anuran species, and are a cost-effective means of determining the status of their populations

    Vegetation‐precipitation controls on Central Andean topography

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    Climatic controls on fluvial landscapes are commonly characterized in terms of mean annual precipitation. However, physical erosion processes are driven by extreme events and are therefore more directly related to the intensity, duration, and frequency of individual rainfall events. Climate also influences erosional processes indirectly by controlling vegetation. In this study, we explore how interdependent climate and vegetation properties affect landscape morphology at the scale of the Andean orogen. The mean intensity, duration, and frequency of precipitation events are derived from the TRMM 3B42v7 product. Relationships between mean hillslope gradients and precipitation event metrics, mean annual precipitation, vegetation, and bedrock lithology in the central Andes are examined by correlation analyses and multiple linear regression. Our results indicate that mean hillslope gradient correlates most strongly with percent vegetation cover ( r  = 0.56). Where vegetation cover is less than 95%, mean hillslope gradients increase with mean annual precipitation ( r  = 0.60) and vegetation cover ( r  = 0.69). Where vegetation cover is dense (>95%), mean hillslope gradients increase with increasing elevation ( r  = 0.74), decreasing inter‐storm duration ( r  = −0.69), and decreasing precipitation intensity by ~0.5°/(mm d −1 ) ( r  = −0.56). Thus, we conclude that at the orogen scale, climate influences on topography are mediated by vegetation, which itself is dependent on mean annual precipitation ( r  = 0.77). Observations from the central Andes are consistent with landscape evolution models in which hillslope gradients are a balance between rock uplift, climatic erosional efficiency and erosional resistance of the landscape determined by bedrock lithology and vegetation. Key Points Hillslope gradients in central Andes increase with increasing vegetation cover Precipitation intensity affects topography most in densely vegetated areas Mean annual precipitation affects erosional efficiency through vegetation coverPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108109/1/jgrf20258.pd

    Quantifying the role of paleoclimate and Andean Plateau uplift on river incision

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/1/jgrf20055-sup-0002-2012JF002533fs02.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/2/jgrf20055.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/99035/3/jgrf20055-sup-0001-2012JF002533fs01.pd

    Targeting the Heat Shock Protein 90 Dimer with Dimeric Inhibitors

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    The design, synthesis and biological evaluation of conformationally constrained coumermycin A1 analogues are reported. Compounds were evaluated against both breast cancer (SKBr3 and MCF7) and prostate cancer (PC3mm2, A549 and HT29) cell lines. Non-noviosylated coumermycin A1 analogues that manifest potent anti-proliferative activity resulting from Hsp90 inhibition are provided, wherein replacement of the stereochemically complex noviose sugar with readily available piperidine rings resulted in ~100 fold increase in anti-proliferative activities as compared to coumermycin A1, producing small molecule Hsp90 inhibitors that exhibit nanomolar activities

    A High-Resolution Spectroscopic Search for the Remaining Donor for Tycho's Supernova

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    In this paper, we report on our analysis using Hubble Space Telescope astrometry and Keck-I HIRES spectroscopy of the central six stars of Tycho's supernova remnant (SN 1572). With these data, we measured the proper motions, radial velocities, rotational velocities, and chemical abundances of these objects. Regarding the chemical abundances, we do not confirm the unusu- ally high [Ni/Fe] ratio previously reported for Tycho-G. Rather, we find that for all metrics in all stars, none exhibit the characteristics expected from traditional SN Ia single-degenerate-scenario calculations. The only possible exception is Tycho-B, a rare, metal-poor A-type star; however, we are unable to find a suitable scenario for it. Thus, we suggest that SN 1572 cannot be explained by the standard single-degenerate model.Comment: 34 pages, 11 Figures, revised and resubmitted to Ap

    Synthesis and Biological Evaluation of Coumarin Replacements of Novobiocin as Hsp90 Inhibitors

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    Since Hsp90 modulates all six hallmarks of cancer simultaneously, it has become an attractive target for the development of cancer chemotherapeutics. In an effort to develop more efficacious compounds for Hsp90 inhibition, novobiocin analogues were prepared by replacing the central coumarin core with naphthalene, quinolinone, and quinoline surrogates. These modifications allowed for modification of the 2-position, which was previously unexplored. Biological evaluation of these compounds suggests a hydrophobic pocket about the 2-position of novobiocin. Anti-proliferative activities of these analogues against multiple cancer cell lines identified 2-alkoxyquinoline derivatives to exhibit improved activity

    Lessons Learned in the Early Stages of a Community-Academic Partnership to Address Health Disparities in a Rural Community

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    In rural Georgia, African American men are burdened by chronic health diseases such as cancer, diabetes, and cardiovascular disease. Community-academic partnerships that leverage community-based participatory research (CBPR) principles can facilitate the adaptation and translation of multilevel programs to address chronic disease prevention and management in rural areas. The objective of this study was to explore key components of the CBPR process that bolstered the early stages of a partnership established between rural-residing community leaders and academic partners in Georgia. Qualitative methodology was used to collect and assess data regarding the initial engagement between the community and academic partners. Findings indicate that five components supported initial engagement: utilizing the public service and outreach arm of the university to connect with rural communities; creating synergy around identified community health needs; encouraging community members to provide input into the research design to ensure the research goals reflect community values; enhancing the capacity of community partners; and following the lead of the community. Findings provide insights into how to begin engaging rural communities in the southeast in order to strengthen the adaptation and translation of initiatives to improve cancer, diabetes and cardiovascular disease outcomes

    Active Full-Shell Grazing-Incidence Optics

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    MSFC has a long history of developing full-shell grazing-incidence x-ray optics for both narrow (pointed) and wide field (surveying) applications. The concept presented in this paper shows the potential to use active optics to switch between narrow and wide-field geometries, while maintaining large effective area and high angular resolution. In addition, active optics has the potential to reduce errors due to mounting and manufacturing lightweight optics. The design presented corrects low spatial frequency error and has significantly fewer actuators than other concepts presented thus far in the field of active x-ray optics. Using a finite element model, influence functions are calculated using active components on a full-shell grazing-incidence optic. Next, the ability of the active optic to effect a change of optical prescription and to correct for errors due to manufacturing and mounting is modeled

    Full-Shell X-Ray Optics Development at NASA Marshall Space Flight Center

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    NASAs Marshall Space Flight Center (MSFC) maintains an active research program toward the development of high-resolution, lightweight, grazing-incidence x-ray optics to serve the needs of future x-ray astronomy missions such as Lynx. MSFC development efforts include both direct fabrication (diamond turning and deterministic computer-controlled polishing) of mirror shells and replication of mirror shells (from figured, polished mandrels). Both techniques produce full-circumference monolithic (primary + secondary) shells that share the advantages of inherent stability, ease of assembly, and low production cost. However, to achieve high-angular resolution, MSFC is exploring significant technology advances needed to control sources of figure error including fabrication- and coating-induced stresses and mounting-induced distortions
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