667 research outputs found

    A phenotypic and genetic analysis of energy balance in dairy cows

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    In dairy cows, the failure or unwillingness to eat sufficient in early lactation when yield is high leads to a state known as negative energy balance (NEB). In this state, cows mobilise body tissue mostly in the form of body lipid in order to make up the difference in energy available from feed ingested and that required to sustain obligatory requirements, such as maintenance, and milk production. A large NEB is an undesirable state since it is associated with increased disease and reduced fertility.Body lipid content can be predicted from visual assessment of the tailhead of cows using a system known as body condition scoring (BCS). Changes in this score over time can therefore be used to predict body lipid changes. I investigated the feasibility of automating the process of collecting condition score using a digital camera and laser lights. The correlation between CS and shape over the tail-head was 0.55 suggesting that it may be possible in future to include digital images in an automated and integrated dairy farm management system.Using random regression analysis, I analysed changes in milk production, feed intake, liveweight and BCS over one to three lactations and calculated energy balance from these daily predictions. These analyses showed that energy balance can be predicted from body measurements without the need to measure feed intake making it practical to use nationally. Using these techniques enabled the genetic analysis of large volumes of field data to predict daily breeding values for energy balance for 1250 progeny test sires. Substantial genetic variation was found in energy balance profiles. The mean total daughter body energy loss at day 305 of lactation was 779 MJ (SD=224 MJ), equivalent in energy terms to about 189 kg milk. Future selection indices may contain an adjustment for the amount of body energy used to support the milk production of a bulls’ daughters leading to a more complete assessment of the utility of a bull.Analysis of data from the Langhill Dairy Research Centre demonstrated that there are differences in the way dairy cows of differing genetic merit for production mobilise body lipid to support lactation and that the amount of concentrate fed also affects the recovery of lost body lipid. Select cows contained about 3200 MJ less energy than control cows at the end of the third lactation and lose and gain body lipid in a cyclical way. Parameters of these curves may be used in future selection indices to allow selection of genotypes that have profiles of body lipid loss and gain commensurate with high yields and long herd life. This may also be useful in future when selection indices contain more traits and farmers and advisors tailor their management to suit the type of cow. It may also provide guidance on how future selection indices should be developed to incorporate traits such as body lipid, traits that enable the robust cow to thrive over many high yielding lactations

    Specific heat anomalies of open quantum systems

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    The evaluation of the specific heat of an open, damped quantum system is a subtle issue. One possible route is based on the thermodynamic partition function which is the ratio of the partition functions of system plus bath and of the bath alone. For the free damped particle it has been shown, however, that the ensuing specific heat may become negative for appropriately chosen environments. Being an open system this quantity then naturally must be interpreted as the change of the specific heat obtained as the difference between the specific heat of the heat bath coupled to the system degrees of freedom and the specific heat of the bath alone. While this difference may become negative, the involved specific heats themselves are always positive; thus, the known thermodynamic stability criteria are perfectly guaranteed. For a damped quantum harmonic oscillator, instead of negative values, under appropriate conditions one can observe a dip in the difference of specific heats as a function of temperature. Stylized minimal models containing a single oscillator heat bath are employed to elucidate the occurrence of the anomalous temperature dependence of the corresponding specific heat values. Moreover, we comment on the consequences for the interpretation of the density of states based on the thermal partitionfunction.Comment: 7 pages, 6 figures, new title and some modifications of the main tex

    New steel industry challenges

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    Afrikanische Soldaten im französisch besetzten Vorarlberg 1945/46

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    Vorarlberg wurde hauptsĂ€chlich von marokkanischen Kolonialtruppen der französischen Armee befreit. Die vorliegende Arbeit behandelt den Aufenthalt dieser Soldaten in Vorarlberg insbesondere unter dem Aspekt welche Diskurse ĂŒber diese Soldaten in der Vorarlberger Bevölkerung und von Seiten französischer Offiziere prĂ€sent waren. Daneben gehe ich auch den soziale Hintergrund der marokkanischen Soldaten und auf die Funktionsweise der französischen Kolonialarmee ein. Ich ziehe sowohl publizierte Quellen wie Memoiren französischer GenerĂ€le, Zeitschriften und Zeitungen als auch Quellen aus Vorarlberger Archiven sowie dem Archiv der französischen Armee heran. Die französische Armee war ein von systematischer Diskriminierung gegenĂŒber den kolonisierten Soldaten in allen Bereichen des militĂ€rischen Leben geprĂ€gtes System. Die voralberger Sichtweisen ĂŒber marokkanischen Soldaten zeigen insbesondere zu den in interner Korrespondenz der Armee geĂ€ußerten Meinungen französischer Offiziere starke Parallelen auf. In beiden ist die Infantilisierung der Kolonialsoldaten ein wichtiges Instrument der Konstruktion ihrer eigenen Überlegenheit. Auch die Ablehnung von Beziehungen zwischen marokkanischen Soldaten und französischen bzw. österreichischen Frauen ist in beiden Diskursen stark prĂ€sent. Gleichzeitig gibt es eine starke Diskrepanz zwischen den Darstellungen in Publikationen der französischen Armee bzw. Offizieren dieser und in der internen Kommunikation der Armee. WĂ€hrend bei ersteren am Ideal der mission civilicatrice festgehalten wird und Frankreich im allgemeinen bzw. die französische Armee im speziellen als Motor der Weiterentwicklung der autochthonen Bevölkerung Afrikas dargestellt wird, kommt in der internen Kommunikation des französischen Generalstabs fĂŒr Marokko zum Ausdruck, dass eine Weiterentwicklung der Soldaten komplett unerwĂŒnscht ist, da man befĂŒrchtete, dass jegliche Horizonterweiterung der Kolonialsoldaten den militĂ€rischen Wert der Kolonialarmee zerstören konnte

    The changing European steel workforce

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