247 research outputs found

    Increasing the use of AI in suckler herds.

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    End of Project ReportReproductive efficiency is a major factor affecting production and economic efficiency of beef herds. For herds using artificial insemination (AI) heat detection rate and calving rate are the two major determinants of compactness of calving and ultimately the calving-to-calving interval. Heat detection is a time consuming repetitive chore that must be carried out up to 5-times each day for as long as AI is used. Heat detection rate, usually measured as submission rate, is hugely variable from herd-toherd but for most herds only between 40% and 70% of cows that exhibit heat are actually detected by the stockman. Despite an increased understanding of the endocrine control of the oestrous cycle the goal of fixed-time insemination is not yet consistently achievable in either cows or heifers treated at different stages of the oestrous cycle and in different physiological states. The overall objective of the this project was to develop an improved cost effective hormonal method to control the time of ovulation to allow beef cows be bred by AI without the need for heat detection. A total of 3 studies were carried out and the results are summarised in this report.Department of Agriculture, Food and the Marin

    Shortening the interval to resumption of ovarian cycles in postpartum beef cows.

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    End of Project Report‱ In beef cows the interval from calving to first ovulation, or postpartum interval, is affected by nutrition and by the suckling effect of the calf. ‱ The suckling effect is the biggest determinant of this interval, comprising: (i) physical contact and (ii) maternal bonding between cow and calf. Restricted suckling and calf isolation induce a rapid resumption of oestrous cycles. ‱ Prepartum nutrition is the next most important determinant of the postpartum interval. Cows that calve in poor body condition have a longer interval than cows that calve in good body condition. ‱ Increasing the level of nutrition in the postpartum period has only a limited effect in shortening the postpartum interval. ‱ In most cows the first postpartum ovulation is silent and is succeeded by a short oestrous cycle of approximately 8-10 days. The first observed oestrus occurs prior to the second ovulation. ‱ When used in combination with calf isolation and restricted suckling, progesterone pre-treatment for 6 days induces oestrus in the majority of cows and eliminates the short oestrous cycle. ‱ The prolonged postpartum interval in beef cows is not due to failure of ovarian follicle development but to failure of successive dominant follicles to ovulate due to the inadequate frequency of LH pulses.European Union 3rd Framework Programme (Contract AIR3-CT94-1124

    Nutrition and Oestrus and Ovarian Cycles in Cattle

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    End of Project ReportThe overall objective of this project was to establish the effects of both long- and short-term changes in nutrition on ovarian follicle dynamics and on the systemic concentrations of metabolic and reproductive hormones. In order to avoid the confounding effects of lactation, suckling and maternal–calf bonding, beef heifers were used in a series of three studies.European Union 3rd Framework Programme (Contract AIR3-CT94-1124

    Application de la mĂ©thode de rĂ©trodiffusion des Ă©lectrons Ă  la mesure en continu des faibles Ă©paisseurs de revĂȘtements lĂ©gers sur mĂ©taux ou alliages lĂ©gers

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    Le problĂšme envisagĂ© concerne la mesure en continu des faibles Ă©paisseurs de revĂȘtements organiques sur mĂ©taux ou alliages lĂ©gers. Nous Ă©tudions les caractĂ©ristiques d'une jauge Ă  rĂ©trodiffusion ÎČ opĂ©rant sous atmosphĂšre d'hĂ©lium. Nous montrons que le fait de travailler sous hĂ©lium amĂ©liore les rĂ©sultats de façon trĂšs importante. L'influence de l'Ă©nergie de la source radio-active et du numĂ©ro atomique du revĂȘtement sont examinĂ©s. Les rĂ©sultats obtenus concernent Ă©galement la prĂ©cision, le temps de mesure ainsi que la surface de l'Ă©chantillon sous investigation

    Does Seasonal Reproductive State Affect the Neuroendocrine Response of the Ewe to a Long-Day Pattern of Melatonin?

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    This study examined whether or not the reproductive response of female sheep to photoperiod varies with seasonal reproductive state. The specific objective was to test the hypothesis that the reproductive response to a long-day pattern of melatonin varies with the reproductive state of the ewe. The response examined was the synchronization of reproductive neuroendocrine induction (rise in serum luteinizing hormone, or LH) following nocturnal infusion of melatonin into pinealectomized ewes for 35 consecutive nights. This infusion restored a pattern of circulating melatonin similar to that in pineal-intact ewes maintained in a long photoperiod (LD 16:8). The ewes had been pinealectomized and without melatonin replacement for 16-25 months prior to the study. They were in differing reproductive states at the start of the infusion, as their endogenous reproductive rhythm had become desynchronized among individuals and with respect to time of year. Noninfused pinealectomized ewes served as controls. Regardless of the reproductive state at the start of the 35-day infusion of the long-day pattern of melatonin, all treated ewes exhibited the same reproductive neuroendocrine response after the infusion was ended. This consisted of a synchronized rise in LH some 6-8 weeks after the infusion was terminated, the maintenance of a high level of serum LH for some 15 weeks, and a subsequent precipitous fall in LH to a very low level. These results provide evidence that a long-day pattern of melatonin can synchronize reproductive neuroendocrine induction in the ewe, regardless of reproductive condition, and thus do not support the hypothesis that this response differs with seasonal reproductive state.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66625/2/10.1177_074873049200700101.pd

    Mental Rotation of Digitally-Rendered Haptic Objects.

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    Sensory substitution is an effective means to rehabilitate many visual functions after visual impairment or blindness. Tactile information, for example, is particularly useful for functions such as reading, mental rotation, shape recognition, or exploration of space. Extant haptic technologies typically rely on real physical objects or pneumatically driven renderings and thus provide a limited library of stimuli to users. New developments in digital haptic technologies now make it possible to actively simulate an unprecedented range of tactile sensations. We provide a proof-of-concept for a new type of technology (hereafter haptic tablet) that renders haptic feedback by modulating the friction of a flat screen through ultrasonic vibrations of varying shapes to create the sensation of texture when the screen is actively explored. We reasoned that participants should be able to create mental representations of letters presented in normal and mirror-reversed haptic form without the use of any visual information and to manipulate such representations in a mental rotation task. Healthy sighted, blindfolded volunteers were trained to discriminate between two letters (either L and P, or F and G; counterbalanced across participants) on a haptic tablet. They then tactually explored all four letters in normal or mirror-reversed form at different rotations (0°, 90°, 180°, and 270°) and indicated letter form (i.e., normal or mirror-reversed) by pressing one of two mouse buttons. We observed the typical effect of rotation angle on object discrimination performance (i.e., greater deviation from 0° resulted in worse performance) for trained letters, consistent with mental rotation of these haptically-rendered objects. We likewise observed generally slower and less accurate performance with mirror-reversed compared to prototypically oriented stimuli. Our findings extend existing research in multisensory object recognition by indicating that a new technology simulating active haptic feedback can support the generation and spatial manipulation of mental representations of objects. Thus, such haptic tablets can offer a new avenue to mitigate visual impairments and train skills dependent on mental object-based representations and their spatial manipulation

    Recommendations for acquisition, interpretation and reporting of whole body low dose CT in patients with multiple myeloma and other plasma cell disorders: a report of the IMWG Bone Working Group

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    Whole Body Low Dose CT (WBLDCT) has important advantages as a first-line imaging modality for bone disease assessment in patients with plasma cell disorders and has been included in the 2014 International Myeloma Working Group (IMWG) criteria for multiple myeloma (MM) definition. Nevertheless, standardization guidelines for the optimal use of WBLDCT in MM patients are still lacking, preventing its more widespread use, both in daily practice and clinical trials. The aim of this report by the Bone Group of the IMWG is to provide practical recommendations for the acquisition, interpretation and reporting of WBLDCT in patients with multiple myeloma and other plasma cell disorders

    Chiral effective field theories of the strong interactions

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    Effective field theories of the strong interactions based on the approximate chiral symmetry of QCD provide a model-independent approach to low-energy hadron physics. We give a brief introduction to mesonic and baryonic chiral perturbation theory and discuss a number of applications. We also consider the effective field theory including vector and axial-vector mesons.Comment: 22 pages, 9 figures, proceedings of "Many-Body Structure of Strongly Interacting Systems", Mainz, Germany, Feb. 23-25 201
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