1,608 research outputs found

    The supply and use of organic material at the deep-sea floor

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    Sediment traps and benthic respirometers have been used to measure the supply of particulate materials to, and the use of organic material by the North Atlantic deep-sea benthos. The area of the sea floor less than 2 kilometers deep is relatively small but accounts for 85% of the total oceanic benthic oxygen consumption, which reflects the primary productivity of the surface waters...

    Species Delimitation: A Case Study in a Problematic Ant Taxon

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    Species delimitation has been invigorated as a discipline in systematics by an influx of new character sets, analytical methods, and conceptual advances. We use genetic data from 68 markers, combined with distributional, bioclimatic, and coloration information, to hypothesize boundaries of evolutionarily independent lineages (species) within the widespread and highly variable nominal fire ant species Solenopsis saevissima, a member of a species group containing invasive pests as well as species that are models for ecological and evolutionary research. Our integrated approach uses diverse methods of analysis to sequentially test whether populations meet specific operational criteria (contingent properties) for candidacy as morphologically cryptic species, including genetic clustering, monophyly, reproductive isolation, and occupation of distinctive niche space. We hypothesize that nominal S. saevissima comprises at least 4-6 previously unrecognized species, including several pairs whose parapatric distributions implicate the development of intrinsic premating or postmating barriers to gene flow. Our genetic data further suggest that regional genetic differentiation in S. saevissima has been influenced by hybridization with other nominal species occurring in sympatry or parapatry, including the quite distantly related Solenopsis geminata. The results of this study illustrate the importance of employing different classes of genetic data (coding and noncoding regions and nuclear and mitochondrial DNA [mtDNA] markers), different methods of genetic data analysis (tree-based and non-tree based methods), and different sources of data (genetic, morphological, and ecological data) to explicitly test various operational criteria for species boundaries in clades of recently diverged lineages, while warning against over reliance on any single data type (e.g., mtDNA sequence variation) when drawing inference

    Analysis of Traffic Crash Data in Kentucky (2013-2017)

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    Executive Summary This report documents an analysis of traffic crash data in Kentucky for the years of 2013-2017. A primary objective of this study was to determine average crash statistics for Kentucky highways. Rates were calculated for various types of highways and for counties and cities. Difference criteria were used for exposure. Average and critical numbers and rates of crashes were calculated for various types of highways in rural and urban areas. These rates used crashes identified on highways where traffic volumes were available. Improved methods of identifying crash locations have resulted in higher rates for the last couple of years. The crash rate data can be used in Kentucky’s procedure to identify locations that have abnormal rates or numbers of crashes. The other primary objective of this study was to provide data that can be used in the preparation of the problem identification portion of Kentucky’s Annual Highway Safety Plan. County and city crash statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented. These general areas include; alcohol involvement, occupant protection, speed, teenage drivers, pedestrians, bicycles, motorcycles, trucks, and vehicle defects. Other areas included in the analysis for which specific recommendations were not made include, school bus crashes and train crashes. The crash data are stored in the Collision Report Analysis for Safer Highways (CRASH) database. This database is updated daily so the number of crashes in a given calendar year will continue to change for a substantial time after the end of that year

    Analysis of Traffic Crash Data in Kentucky (2012-2016)

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    This report documents an analysis of traffic crash data in Kentucky for the years of 2012 through 2016. A primary objective of this study was to determine average crash statistics for Kentucky highways. Rates were calculated for various types of highways and for counties and cities. Difference criteria were used for exposure. The other primary objective of this study was to provide data that can be used in the preparation of the problem identification portion of Kentucky’s Annual Highway Safety Plan. County and city crash statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented

    Improvement of Fatal Crash Analysis and Follow-Up

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    Executive Summary Fatalities resulting from traffic crashes in Kentucky increased from a low of 638 in 2013 to 834 in 2016 (a 31% increase), and there is not a full understanding of the underlying causes for this trend. This study analyzes fatal crashes using data from both Kentucky’s crash reports and the National Highway Traffic Safety Administration’s (NHTSA) Fatal Accident Reporting System (FARS) to identify countermeasures to combat increasing fatal crash rates. In addition, this study compares Kentucky’s crash reports to the fatal crash data in FARS to identify data inconsistencies and recommend procedures to eliminate these inconsistencies. Emphasis was placed on fatal crashes involving alcohol and drugs because police-reported crash data in Kentucky do not clearly represent the magnitude of alcohol- and drug-related fatal crashes. More detailed analysis of fatal crashes involving alcohol and drugs provides an understanding of the patterns of impaired drivers in terms of their overall characteristics, crash locations, time of day, types of drugs, and other identifying factors that affect patterns and behavior. The study identified crashes involving mature drivers (65+) and lane departure crashes as fatal crash types with the greatest increases since 2013. Pedestrian, motorcycle, intersection, and impairment-related fatal crashes also demonstrated increasing fatal crash rates in 2016. Analysis of restraint use showed that almost 54% of the fatally injured people in 2016 were not wearing a seatbelt when one was available to them. Of those fatally injured in a motorcycle crash, nearly 72% were not wearing a helmet. Based on FARS data, there were 160 fatal crashes in Kentucky in which a driver tested positive for alcohol and 266 fatal crashes where a driver tested positive for at least one drug. The drugs most frequently found in drivers were tetrahydrocannabinol (THC), hydrocodone, and Xanax. In general, fatal crash frequency spiked during the morning and afternoon peak hour periods, with fatalities occurring more frequently between 11 am and 11 pm. The percent of potentially impaired (alcohol- and drug-involved) fatal crashes increased between 5 pm and 4 am from around 40% to a peak of 81% at 4 am. Eastern Kentucky was identified as a region with high fatal crash rates and potentially impaired fatal crash rates. Both Ballard and Union Counties in Western Kentucky showed high fatality and potentially impaired fatality rates as well. Comparisons between the FARS database and Kentucky’s crash reports revealed inconsistencies between the date, time, location, injury severity, and impairment indications in the two databases. Recommendations stemming from this study were divided into four categories: enforcement, legislation/licensing, public involvement, and data collection. The recommendations are aimed at reducing crash fatalities, improving crash data collection, and improving consistency between Kentucky’s crash reports and the national FARS database

    Distribution and Prevalence of Wolbachia Infections in Native Populations of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae)

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    Wolbachia are endosymbiotic bacteria that commonly infect arthropods. These bacteria induce a number of phenotypes in their hosts, including cytoplasmic incompatibility, thelytokous parthenogenesis, feminization, and male killing. We surveyed native South American populations of the fire ant Solenopsis invicta Buren for Wolbachia infections by using a diagnostic polymerase chain reaction assay. In addition, we determined the fidelity of vertical transmission of the bacteria from mother to offspring in this species by assaying daughters in 24 simple-family (monogyne) colonies. Infections were common in many parts of the extensive native range of S. invicta. However, the proportion of individuals infected varied greatly among samples, ranging from zero in several populations from the northerly parts of the range to >90% in more southerly populations. Possible explanations for this variation in the prevalence of Wolbachia infections are discussed. A survey of the two social forms of S. invicta from four geographic areas showed that the prevalence of Wolbachia infections consistently was higher in the monogyne form (single queen per colony) than the sympatric polygyne form (multiple queens per colony). One likely explanation for this trend is that the selective regimes acting on Wolbachia in the two forms differ because of the dissimilar reproductive strategies used by each form. Finally, overall transmission efficiency was found to be very high (>99%), making it unlikely that imperfect transmission prevents the spread of the microbe to near fixation in native population

    Distribution of the Two Social Forms of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae) in the Native South American Range

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    Polygyne (multiple queen) colony social organization in the fire ant Solenopsis invicta Buren is always associated with the presence of a particular class of alleles at the gene Gp-9. We used diagnostic polymerase chain reaction assays capable of distinguishing these alleles to determine the location of polygyne populations in the native South American range of this species. We found that polygyny occurs in a mosaic pattern with respect to the more common monogyne (single queen) social form, a pattern superficially similar to that seen in the introduced range in the United States. However, polygyny appears to be relatively restricted in its geographical prevalence in the native range compared with the introduced range. This difference may stem from higher dispersal rates in the introduced range, which are associated with greater opportunities for human-mediated transport of mated queens or colony fragments. On the basis of our distributional data and results from other studies, the southern part of the native range of S. invicta, particularly northeastern Argentina, is emerging as the most likely geographic source of the founders of the U.S. populatio

    A Randomized Cross-Over Trial Comparing the Effect of Intramuscular Versus Intranasal Naloxone Reversal of Intravenous Fentanyl on Odor Detection in Working Dogs

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    Fentanyl is a potent opioid used clinically as a pain medication and anesthetic but has recently seen a sharp rise as an illicit street drug. The potency of fentanyl means mucous membrane exposure to a small amount of the drug can expose first responders, including working canines, to accidental overdose. Naloxone, a fast-acting opioid antagonist administered intranasally (IN) or intramuscularly (IM) is currently carried by emergency personnel in the case of accidental exposure in both humans and canines. Despite the fact that law enforcement relies heavily on the olfactory abilities of canine officers, the effects of fentanyl exposure and subsequent reversal by naloxone on the olfactory performance of canines are unknown. In a block-randomized, crossover trial, we tested the effects of IN and IM naloxone on the abilities of working dogs to recognize the odor of Universal Detection Calibrant (UDC) prior to, and two, 24, and 48 h after intravenous fentanyl sedation and naloxone reversal. No detectable influence of fentanyl sedation and naloxone reversal on the dogs’ olfactory abilities was detected. We also found no difference in olfactory abilities when dogs received IN or IM naloxone. Together, results suggest no evidence that exposure to intravenous fentanyl followed by naloxone reversal impairs canine olfactory ability under these conditions
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