120 research outputs found
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Discriminating between landslide sites and potentially unstable terrain using topographic indices
A landslide inventory, statistical analyses and a Geographic Information System (GIS) are used to analyze landslide sites and potentially unstable terrain in the Oregon Coast Range. The objectives are to evaluate the efficacy of locating landslide sites with topographic variables and discriminate the difference between sites where landslides have and have not occurred. The population of known landslides are characterized as up-slope, non-road related, and associated with 1996 storm events. Topographic variables are derived from a Digital Elevation Model (DEM) for index construction forming six groups; i) slopes, ii) contributing areas, iii) ratios of slope and contributing area, iv) curvature v) infinite slope models, and vi) functions of slope and contributing area based on statistical models. Index groups employ different algorithms. Index performance is measured with landslide and aerial densities. Cumulative landslide occurrence is plotted against cumulative area on a continuous domain of the index to locate a maximum landslide density on equal size areas. Indices are used to generate model definitions of potentially unstable terrain based on similarity to the landslide population. Aerial densities of potentially unstable terrain based on index definitions are determined but no common metric is achieved. Statistical analyses on spatially stratified data suggest a significant (α < 0.05) difference between landslides sites and adjoined terrain. The minimum resolution at which a significant difference is achieved based on spatial stratification is a three cell radius surrounding the slide population. Curvature and area discriminate better than simple slope and topographic ratios. The relative performance is mostly a function of DEM error and resolution, and spatial correlation. Hydrologic geomorphic models perform about as well as the topographic ratios, and much less than the simple area index. There is no statistical evidence to suggest that the hydrologic geomorphic models accurately describe a threshold in the Mapleton slide population. The lack of significance is likely due to limitations on the available parameter sets. Logistic regression produced an index with the highest discrimination performance due to a maximum likelihood algorithm. Regression models have a physical basis in and parallel the behavior of linked hydrologic geomorphic and slope stability models. The measured differences in performance are a useful assessment of the DEM – index combination
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Public health impact assessment : a science-based methodology for comparing biological agents
Humans have long suffered the effects of disease causing biological agents. Today bioterrorism appears to be on the rise while at the same time global and ecological changes have resulted in the emergence of new diseases. Potential repercussions of an epidemic pose immense challenges requiring a methodical approach to align priorities and resources. Past assessments evaluating the potential impact of an introduction of various biological agents have often produced disparate results, primarily due to underlying differences in their comparison methodologies and data inputs. Divergent outcomes of these studies have resulted in very broad biopreparedness strategies without a consensus on how to target limited resources on just those agents that could have the greatest public health impact. Further hampering biopreparedness is a paucity of data not often recognized due to reliance on subject matter experts and qualitative processes. In consideration of these challenges the present study evaluated thirty three bacterial and viral agents using the full range of available data in the scientific literature. Quantitative metrics were combined to rank the potential impact posed by an agent, relative to others considered. Resultant rankings were obtained for low, most likely and high potential public health impacts for both untreated and treated mortality endpoints. Through the incorporation of the full range of available data, results of the current assessment made strides to unify conflicting outcomes obtained in past assessments
Joint MiRNA/mRNA expression profiling reveals rhanges consistent with development of dysfunctional corpus luteum after weight gain
<div><p>Obese women exhibit decreased fertility, high miscarriage rates and dysfunctional corpus luteum (CL), but molecular mechanisms are poorly defined. We hypothesized that weight gain induces alterations in CL gene expression. RNA sequencing was used to identify changes in the CL transcriptome in the vervet monkey (<i>Chlorocebus aethiops</i>) during weight gain. 10 months of high-fat, high-fructose diet (HFHF) resulted in a 20% weight gain for HFHF animals vs. 2% for controls (p = 0.03) and a 66% increase in percent fat mass for HFHF group. Ovulation was confirmed at baseline and after intervention in all animals. CL were collected on luteal day 7–9 based on follicular phase estradiol peak. 432 mRNAs and 9 miRNAs were differentially expressed in response to HFHF diet. Specifically, miR-28, miR-26, and let-7b previously shown to inhibit sex steroid production in human granulosa cells, were up-regulated. Using integrated miRNA and gene expression analysis, we demonstrated changes in 52 coordinately regulated mRNA targets corresponding to opposite changes in miRNA. Specifically, 2 targets of miR-28 and 10 targets of miR-26 were down-regulated, including genes linked to follicular development, steroidogenesis, granulosa cell proliferation and survival. To the best of our knowledge, this is the first report of dietary-induced responses of the ovulating ovary to developing adiposity. The observed HFHF diet-induced changes were consistent with development of a dysfunctional CL and provide new mechanistic insights for decreased sex steroid production characteristic of obese women. MiRNAs may represent novel biomarkers of obesity-related subfertility and potential new avenues for therapeutic intervention.</p></div
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Energy input and dissipation in a temperate lake during the spring transition
ADCP and temperature chain measurements have been used to estimate the rate of energy input by wind stress to the water surface in the south basin of Windermere. The energy input from the atmosphere was found to increase markedly as the lake stratified in spring. The efficiency of energy transfer (Eff), defined as the ratio of the rate of working in near-surface waters (RW) to that above the lake surface (P10), increased from ∼0.0013 in vertically homogenous conditions to ∼0.0064 in the first 40 days of the stratified regime. A maximum value of Eff∼0.01 was observed when, with increasing stratification, the first mode internal seiche period decreased to match the diurnal wind period of 24 h. The increase in energy input, following the onset of stratification was reflected in enhancement of the mean depth-varying kinetic energy without a corresponding increase in wind forcing. Parallel estimates of energy dissipation in the bottom boundary layer, based on determination of the structure function show that it accounts for ∼15% of RW in stratified conditions. The evolution of stratification in the lake conforms to a heating stirring model which indicates that mixing accounts for ∼21% of RW. Taken together, these estimates of key energetic parameters point the way to the development of full energy budgets for lakes and shallow seas
Using Basic Science to Design a Clinical Trial: Baseline Characteristics of Women Enrolled in the Kronos Early Estrogen Prevention Study (KEEPS)
Observational and epidemiological studies suggest that menopausal hormone therapy (MHT) reduces cardiovascular disease (CVD) risk. However, results from prospective trials showed neutral or adverse effects most likely due to differences in participant demographics, such as age, timing of initiation of treatment, and preexisting cardiovascular disease, which reflected in part the lack of basic science information on mechanisms of action of hormones on the vasculature at the time clinical trials were designed. The Kronos Early Estrogen Replacement Study (KEEPS) is a prospective, randomized, controlled trial designed, using findings from basic science studies, to test the hypothesis that MHT when initiated early in menopause reduces progression of atherosclerosis. KEEPS participants are younger, healthier, and within 3 years of menopause thus matching more closely demographics of women in prior observational and epidemiological studies than women in the Women’s Health Initiative hormone trials. KEEPS will provide information relevant to the critical timing hypothesis for MHT use in reducing risk for CVD
Analyse beckenweiter interner Wellen im Bodensee-Obersee
Available from TIB Hannover: RA 1064(123) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Review on the modeling of short-period internal waves in lakes with focus on Lake Constance. Literaturrecherche zur Modellierung kurzperiodischer interner Wellen in Seen mit Schwerpunkt auf dem Bodensee
Lake Constance - the second largest lake of the European Alps - and its hydrodynamic behavior are the topic of this report. It is the essence of a review that was done as part of preparations for an investigation on the internal wave field of the lake and its numerical modeling. The material presented here does not attempt to be complete. It is a reference for the ongoing study. To account for the German language as the local language at Lake Constance a vocabulary is included at the end of the report. The focus of this review is twofold: First, facts of Lake Constance are presented briefly. The second part reviews the state of research in the field of internal waves in stratified lakes and their modeling as well as previous and ongoing research on Lake Constance. The goal of this review is to reveal shortcomings and open questions. Lists with references, useful addresses concerning Lake Constance and a brief vocabulary complement the report. The author acknolwledges the invaluable advice that he received during many discussions on the topic. Special thanks go to Prof. Joerg Imberger and the members of the CWR, Dr. Ulrich Lang, Dipl.-Ing. Bernhard Keim, Dr. Erich Baeuerle, Dr. Johannes Ilmberger and Dipl.-Mech. Lars Umlauf for fruitful discussions and contributions to this report. (orig.)Available from TIB Hannover: RN 7077(269) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
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