2,769 research outputs found

    Field guide to requiem sharks (Elasmobranchiomorphi: Carcharhinidae) of the Western North Atlantic

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    Identification problems are common for many sharks due to a general lack of meristic characteristics that are typically useful for separating species. Other than number of vertebrae and number and shape of teeth, identifications are frequently based on external features that are often shared among species. Identification problems in the field are most prevalent when live specimens are captured and releasing them with a minimum of stress is a priority (e.g., shark tagging programs). Identifications must be accurate and conducted quickly but this can be challenging, especially if specimens are very active or too large to be landed without physical damage. This field guide was designed primarily for use during field studies and presents a simplified method for identifying the 21 species of western North Atlantic Ocean sharks belonging to the family Carcharhinidae (carcharhinids). To assist with identifications a dichotomous key to Carcharhinidae was developed, and for the more problematic Carcharhinus species (12 species), separation sheets based on important distinguishing features were constructed. Descriptive text and illustrations provided in the species accounts were developed from field observations, photographs, and published references. (PDF file contains 36 pages.

    Field Guide to the Searobins (Prionotus and Bellator) in the Western North Atlantic

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    Species identifications of Prionotus and Bellator are often difficult under field conditions owing to the large number of species and their overlapping taxonomic characteristics. This key is intended to provide a simplified, accurate means to identify adult searobins greater than 10 cm standard length. All recognized species from the western North Atlantic, the Gulf of Mexico, and Caribbean Sea are included. (PDF file contains 30 pages.

    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.

    Empirical Characteristics of Affordable Care Act Risk Transfer Payments

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    Under the Affordable Care Act (ACA), insurers cannot engage in medical underwriting and thus face perverse incentives to engage in risk selection and discourage low-value patients from enrolling in their plans. One ACA program intended to reduce the effects of risk selection is risk adjustment. Under a risk adjustment program, insurers with less healthy enrollees receive risk transfer payments from insurers with healthier enrollees. Our goal is to understand the elements driving risk transfers. First, the distribution of risk transfers should be based on random health shocks, which are unpredictable events that negatively affect health status. Second, risk transfers could be influenced by factors unique to each insurer, such as certain plans attracting certain patients, the extent to which carriers engage in risk selection, and the degree of upcoding. We create a publicly available dataset using Centers for Medicare and Medicaid Services data that includes insurer risk transfer payments, costs, and premiums for the 2014-2017 benefit years. Using this dataset, we find that the empirical distribution of risk transfer payments is not consistent with the lack of risk selection as measured by the ACA risk transfer formula. Over all states included in our dataset, at least 60% of the volume of transfers cannot be accounted for by a purely normal model. Because we find that it is very unlikely that risk transfer payments are caused solely by random shocks that reflect health events of the population, our work raises important questions about the causes of heterogeneity in risk transfers.Comment: 33 pages, 2 figure

    Partial Replacement of Portland Cement by Granulated Cupola Slag – Sustainable Option for Concrete of Low Permeability

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    This paper presents the results of investigation on the potentials of cupola slag as a partial replacement option for ordinary Portland cement (OPC) in applications requiring low permeable concrete. The chemical analysis of granulated cupola furnace slag (GCFS), its fineness, bulk density, specific gravity, and the standard consistency and setting times of binary OPC and GCFS pastes were conducted. Furthermore, concrete mixes of 0.55 water/cement ratio were produced using 1:2:4 ratio (volume basis) at 0%, 5%, 10% and 15% replacement levels of OPC by GCFS and the workability and permeability of the fresh concrete were determined. Thirty six (36) standard 150mm cubes were cast from the various concrete mixes, cured for 7, 21 and 28 days and crushed to determine their compressive strengths. The results of the tests showed that within the OPC replacement range investigated, the compressive strength of concrete progressively increased at all curing ages as the replacement level of OPC increased and attained a maximum value of 29.8 N/mm2 at 28 days for 15% OPC replacement, which amounted to a 31.9% increase above the compressive strength of the reference concrete. In addition, the porosity of concrete decreased as the replacement level of OPC by GCFS increased. The chemical analysis of GCFS also indicated that it has pozzolanic properties. The above results indicate the suitability of granulated cupola furnace slag for use in concrete for which reduced permeability is an essential performance requirement. Keywords: cupola slag, low permeable concrete, compressive strength, chemical analysis, sustainabl

    Visualization of the Small Airways:What It Is and Why It Matters

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    When the earth transitioned to an oxygen-containing atmosphere, many bacterial species were killed by the free radicals that developed in their cytoplasm. New life forms took advantage of this change by evolving to use oxygen as the final resting place for electrons involved in the Krebs cycle. Animals today rely on getting oxygen into the blood stream and getting carbon dioxide out by ventilation through sequentially smaller and smaller tubes until diffusion takes over, finally reaching the terminal respiratory bronchiole and its associated alveoli for gas exchange. All animals are obligate aerobes. One group has estimated that there are 274 to 790 million alveoli in the healthy adult lung. In this issue of Radiology, Kim et al describe a visualization method to study the invisible small airways (seven to 30th generation) that move air from the trachea to the peripheral airways and back again for normal ventilation

    Occurrence and Distribution of Mosquitoes (Diptera: Culicidae) of Public Health Importance on the Island of Oahu

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    The Vector Control Branch of the Hawaii State Department of Health has accumulated a large volume of written inspection data on pests of public health for the island of Oahu. By far, the greatest amount of arthropod pest information available is on mosquitoes. The objectives of this study were to conduct a survey of the occurrence of mosquito complaints on Oahu over a 10-year period, determine the distribution of complaints over time, graphically compare mosquito occurrence within and between district/areas, and correlate mosquito occurrence and distribution with season. Mosquito data were drawn from inspection reports from 1990 to 1999, population information was obtained from Hawaii Census and State of Hawaii Data Books, 125 district/area geographic locations were defined, and mosquito occurrence and distribution were adjusted for population and mapped using ArcView GIS 3.2. Most of the mosquito activity was found within the central, south and east urban districts. Drier areas from Kalihi Kai to Portlock had the highest number of complaints, and the levels of mosquito activity were highest during the winter, spring and summer. The primary mosquito species recorded was Aedes albopictus (Skuse), the Asian tiger mosquito, and the main breeding sources were various containers, plus bromeliad plants. Aedes albopictus populations are being maintained in urban districts by human activities. As a result, dengue transmission is possible in the drier, urban areas of Oahu. These results indicate that educational programs should be carried out in late fall and early spring, and that residential mosquito surveys may be concentrated in a limited number of district/areas