1,704 research outputs found

    Additions to a revision of the shark genus Carcharhinus: Synonymy of Aprionodon and Hypoprion, and description of a new species of Carcharhinus (Carcharhinidae)

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    Features of the valid nominal species of Aprionodon Gill (isodon Valenciennes) and Hypoprion Muller and Henle (hemiodon Valenciennes, macloti Muller and Henle, and signatus Poey), plus those of a previously unrecognized species here described as Carcharhinus leiodon n.sp., are examined and compared with those of Carcharhinus Blainville. Features studied include morphometrics, vertebral numbers and other vertebral characteristics, tooth numbers, color pattern, and some other aspects of external morphology. It is concluded that on these features C. leiodon n.sp. is entirely encompassed within the parameters of Carcharhinus, and that, although A. isodon, H. hemiodon, H. macloti, and H. signatus each extend the range of diversity of Carcharhinus in one or more features, A. isodon is not uniquely different from Carcharhinus, and there is no common pattern of difference between the three species of Hypoprion and Carcharhinus. Accordingly, and because the nature of the teeth of Aprionodon and Hypoprion has been found insufficient to warrant generic distinction from Carcharhinus, the genera Aprionodon and Hypoprion are synonymised with Carcharhinus. A diagnosis and description are given for each of the above species. The descriptions include measurements, counts, and line illustrations that show the whole shark in lateral view, underside of head, nostril, and teeth. The geographic distribution is summarized, as are also the meager biological data available on number of embryos, size at birth, size at sexual maturity, and maximum size. (PDF file contains 32 pages.

    Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF) calibration of the Upper Atmosphere Research Satellite (UARS) sensors

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    Flight Dynamics Facility (FDF) responsibilities for calibration of Upper Atmosphere Research Satellite (UARS) sensors included alignment calibration of the fixed-head star trackers (FHST's) and the fine Sun sensor (FSS), determination of misalignments and scale factors for the inertial reference units (IRU's), determination of biases for the three-axis magnetometers (TAM's) and Earth sensor assemblies (ESA's), determination of gimbal misalignments of the Solar/Stellar Pointing Platform (SSPP), and field-of-view calibration for the FSS's mounted both on the Modular Attitude Control System (MACS) and on the SSPP. The calibrations, which used a combination of new and established algorithms, gave excellent results. Alignment calibration results markedly improved the accuracy of both ground and onboard Computer (OBC) attitude determination. SSPP calibration results allowed UARS to identify stars in the period immediately after yaw maneuvers, removing the delay required for the OBC to reacquire its fine pointing attitude mode. SSPP calibration considerably improved the pointing accuracy of the attached science instrument package. This paper presents a summary of the methods used and the results of all FDF UARS sensor calibration

    Solar array thermal snap and the characteristics of its effect on UARS

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    The single solar array on the Upper Atmosphere Research Satellite (UARS) is subjected to a thermal distortion when the spacecraft enters and exits the Earth's shadow. The distortion results in a torque that alters the spacecraft attitude. Due to the sudden nature of the attitude discontinuity, the effect has been termed 'thermal snap'. Thermal snap has also been experienced by Landsats 4 and 5. Analyses by the spacecraft builder addressed the impact of the resultant torque on the onboard control system. This paper discusses the results of comparisons between the predicted effects of thermal snap on UARS and actual attitude solutions from UARS telemetry data. In addition, this paper describes the characteristics of the thermal snap on UARS in terms of maximum displacement, solar beta angle, and solar array drive angle. Comparisons are made between the actual times of thermal snaps and the predicted spacecraft sunrise and sunset times. The effects of the UARS thermal snap are summarized and a general comment is made relating possible effects of thermal snap on other satellites. Also, an analysis of UARS attitude solutions that span periods of thermal snap was performed to determine whether the gyro sampling time of 1/8 second is sufficient to properly model the resulting spacecraft attitude without compromising the accuracy requirements. The results of this analysis are discussed

    Beef in Burgundy

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    A recipe for beef in Burgundy

    Recent Developments in Beef Cattle Improvement

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    Profit from cattle enterprises is influenced by the value of sale animals, less the costs of their production. Ever-changing production and economic circumstances provide both threats and opportunities to cow-calf producers, bull breeders and feedlotters. Feeding strategies and other aspects of management typically require continuous between- and within-year modification in order to optimize margins. Responses to such management changes typically occur immediately. In contrast, genetic improvement is a long-term exercise with within-breed changes from selection seldom exceeding 1-2% per year. During favorable periods in the cow-calf economy, producers may feel that there is little need for genetic improvement. Then, during economic downturns, producers may feel they can’t afford to invest in genetic improvement. Both these behaviors lead to suboptimal rates of genetic improvement

    Investigation of Models and Estimation Techniques for GPS Attitude Determination

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    Much work has been done in the Flight Dynamics Analysis Branch (FDAB) in developing algorithms to met the new and growing field of attitude determination using the Global Positioning SYstem (GPS) constellation of satellites. Flight Dynamics has the responsibility to investigate any new technology and incorporate the innovations in the attitude ground support systems developed to support future missions. The work presented here is an investigative analysis that will produce the needed adaptation to allow the Flight Dynamics Support System (FDSS) to incorporate GPS phase measurements and produce observation measurements compatible with the FDSS. A simulator was developed to produce the necessary measurement data to test the models developed for the different estimation techniques used by FDAB. This paper gives an overview of the current modeling capabilities of the simulator models and algorithms for the adaptation of GPS measurement data and results from each of the estimation techniques. Future analysis efforts to evaluate the simulator and models against inflight GPS measurement data are also outlined

    Pain medicine content, teaching and assessment in medical school curricula in Australia and New Zealand

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    Background: The objective of pain medicine education is to provide medical students with opportunities to develop their knowledge, skills and professional attitudes that will lead to their becoming safe, capable, and compassionate medical practitioners who are able to meet the healthcare needs of persons in pain. This study was undertaken to identify and describe the delivery of pain medicine education at medical schools in Australia and New Zealand. Method: All 23 medical schools in Australia and New Zealand in 2016 were included in this study. A structured curriculum audit tool was used to obtain information on pain medicine curricula including content, delivery, teaching and assessment methods. Results: Nineteen medical schools (83%) completed the curriculum audit. Neurophysiology, clinical assessment, analgesia use and multidimensional aspects of pain medicine were covered by most medical schools. Specific learning objectives for pain medicine were not identified by 42% of medical schools. One medical school offered a dedicated pain medicine module delivered over 1 week. Pain medicine teaching was delivered at all schools by a number of different departments throughout the curriculum. Interprofessional learning (IPL) in the context of pain medicine education was not specified by any of the medical schools. The mean time allocated for pain medicine teaching over the entire medical course was just under 20 h. The objective structured clinical examination (OSCE) was used by 32% of schools to assess knowledge and skills in pain medicine. 16% of schools were unsure of whether any assessment of pain medicine education took place. Conclusion: This descriptive study provides important baseline information for pain medicine education at medical schools in Australia and New Zealand. Medical schools do not have well-documented or comprehensive pain curricula that are delivered and assessed using pedagogically-sound approaches considering the complexity of the topic, the prevalence and public health burden of pain

    Accuracies of Genomic Prediction in Beef Cattle

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    The objective of this study was to derive and evaluate the accuracies of molecular breeding values (MBV) for economically relevant traits for commercial implementation in several beef cattle breeds. We developed MBV forHereford, Red Angus and Simmental breeds. Accuracies of MBV ranged from 0.18 to 0.45 in Hereford, 0.37 to 0.85 in Red Angus, and from 0.29 to 0.65 in Simmental using within breed genomic predictions. Single breed genomic predictions had no utility when applied to other breeds. However, the accuracies of MBV improved for some breeds when predictions were derived using multi-breed reference populations. These results have now been implemented as routine predictions for breeders of American Hereford, American Red Angus and American Simmental beef cattle. Similar findings will soon be extended to other breeds

    Developing a Reduced SNP Panel for Low-cost Genotyping in Beef Cattle

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    The objective of this study was to develop a low-density reduced SNP panel (RP) that could capture most of the predictive ability of a 50K panel for six important traits (birth, weaning and yearling weights; calving ease direct; marbling; and rib eye area) in beef cattle. More than 15,000 animals from six cattle breeds genotyped with 50K were used to select markers highly associated with target traits. Accuracies of direct genomic breeding values (DGV) were calculated for 3 independent validation populations using either 50K or RP. Accuracies of DGV obtained from RP were comparable with those obtained from 50K (\u3e75% predictive ability of 50K) while the size of RP i
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