465 research outputs found

    Nutritional management for reproductive efficiency

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    Nutrition influences reproductive efficiency and the survival of lambs and weaners but the costs of supplementary feeding or maintaining low stocking rates are not justified by the resulting income from higher lamb weaning rates and reduced weaner mortality. The current practice of segmenting the ewe flock using ultrasound scanning to determine the number of foetuses still results in groups of ewes with a wide range of condition scores and with widely differing nutritional requirements. This report describes an approach to precision management of pregnant ewes and weaners that is based on the e-sheep platform of technologies and uses computer-directed drafting for nutritional management of individual animals and walk-through weighing to monitor changing nutritional status. It is estimated that the cost of feeding a thousand-ewe flock can be reduced from 14,000forfeedingallanimalsto14,000 for feeding all animals to 3300 for targeted feeding of 25% of ewes requiring additional nutrition and 20% of weaners at risk of dying. The cost of the targeted feeding strategy is more than justified by the value of additional 12-month-old animals, which is $9000. The e-sheep precision nutrition system is not attractive to industry at this stage because of the cost of the e-sheep infrastructure, the perceived complexity of the technology and the requirement for further research, but it is expected to be a commercial option within three years

    An exceedance score for the assessment of the impact of nitrogen deposition on habitats in the UK

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    Large areas of nitrogen-sensitive habitats are currently estimated to be in exceedance of their critical loads (CLs) as indicators for protection from nitrogen deposition. In the UK, deposition estimates from the semi-empirical Concentration Based Estimated Deposition (CBED) model are used for official reporting of current exceedances. The UK Integrated Assessment Model (UKIAM) framework is designed to provide future projections of concentrations and deposition due to projected changes in emissions. UKIAM has been extended to provide alternative deposition estimates aligned with those of CBED, and the results combined with the range in habitat CL values to create an exceedance score, leading to a probabilistic evaluation of CL exceedances. The utility of the method is demonstrated by analysing a series of hypothetical scenarios. It is shown that NH3 mitigation is likely to be four times more effective in reducing CL exceedances in the UK than the mitigation of NOx emissions

    Distinct Stromal Cell Factor Combinations Can Separately Control Hematopoietic Stem Cell Survival, Proliferation, and Self-Renewal

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    SummaryHematopoietic stem cells (HSCs) are identified by their ability to sustain prolonged blood cell production in vivo, although recent evidence suggests that durable self-renewal (DSR) is shared by HSC subtypes with distinct self-perpetuating differentiation programs. Net expansions of DSR-HSCs occur in vivo, but molecularly defined conditions that support similar responses in vitro are lacking. We hypothesized that this might require a combination of factors that differentially promote HSC viability, proliferation, and self-renewal. We now demonstrate that HSC survival and maintenance of DSR potential are variably supported by different Steel factor (SF)-containing cocktails with similar HSC-mitogenic activities. In addition, stromal cells produce other factors, including nerve growth factor and collagen 1, that can antagonize the apoptosis of initially quiescent adult HSCs and, in combination with SF and interleukin-11, produce >15-fold net expansions of DSR-HSCs ex vivo within 7 days. These findings point to the molecular basis of HSC control and expansion

    Are There Quantum Effects Coming from Outside Space-time? Nonlocality, free will and "no many-worlds"

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    Observing the violation of Bell's inequality tells us something about all possible future theories: they must all predict nonlocal correlations. Hence Nature is nonlocal. After an elementary introduction to nonlocality and a brief review of some recent experiments, I argue that Nature's nonlocality together with the existence of free will is incompatible with the many-worlds view of quantum physics.Comment: Talk presented at the meeting "Is Science Compatible with Our Desire for Freedom?" organised by the Social Trends Institute at the IESE Business School in Barcelona, Octobre 201

    Identification of potential “Remedies” for Air Pollution (nitrogen) Impacts on Designated Sites (RAPIDS)

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    Atmospheric nitrogen (N) deposition is a significant threat to semi-natural habitats and species in the UK, resulting in on-going erosion of habitat quality and declines in many species of high conservation value. The project focused on impacts and remedies for designated conservation sites, especially Natura 2000 sites protected under the EU Habitats Directive. However, the approach and certainly the measures could be equally applied to other areas of high conservation value. Evidence was drawn together to develop a framework for identifying key N threats at individual sites as a basis to target mitigation options in the context of potential legislative, voluntary and financial instruments

    Bosonic sector of the two-dimensional Hubbard model studied within a two-pole approximation

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    The charge and spin dynamics of the two-dimensional Hubbard model in the paramagnetic phase is first studied by means of the two-pole approximation within the framework of the Composite Operator Method. The fully self-consistent scheme requires: no decoupling, the fulfillment of both Pauli principle and hydrodynamics constraints, the simultaneous solution of fermionic and bosonic sectors and a very rich momentum dependence of the response functions. The temperature and momentum dependencies, as well as the dependency on the Coulomb repulsion strength and the filling, of the calculated charge and spin susceptibilities and correlation functions are in very good agreement with the numerical calculations present in the literature

    Non-Markovian entanglement dynamics in coupled superconducting qubit systems

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    We theoretically analyze the entanglement generation and dynamics by coupled Josephson junction qubits. Considering a current-biased Josephson junction (CBJJ), we generate maximally entangled states. In particular, the entanglement dynamics is considered as a function of the decoherence parameters, such as the temperature, the ratio râ‰ĄÏ‰c/ω0r\equiv\omega_c/\omega_0 between the reservoir cutoff frequency ωc\omega_c and the system oscillator frequency ω0\omega_0, % between ω0\omega_0 the characteristic frequency of the %quantum system of interest, and ωc\omega_c the cut-off frequency of %Ohmic reservoir and the energy levels split of the superconducting circuits in the non-Markovian master equation. We analyzed the entanglement sudden death (ESD) and entanglement sudden birth (ESB) by the non-Markovian master equation. Furthermore, we find that the larger the ratio rr and the thermal energy kBTk_BT, the shorter the decoherence. In this superconducting qubit system we find that the entanglement can be controlled and the ESD time can be prolonged by adjusting the temperature and the superconducting phases Ίk\Phi_k which split the energy levels.Comment: 13 pages, 3 figure

    Double quantum dot turnstile as an electron spin entangler

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    We study the conditions for a double quantum dot system to work as a reliable electron spin entangler, and the efficiency of a beam splitter as a detector for the resulting entangled electron pairs. In particular, we focus on the relative strengths of the tunneling matrix elements, the applied bias and gate voltage, the necessity of time-dependent input/output barriers, and the consequence of considering wavepacket states for the electrons as they leave the double dot to enter the beam splitter. We show that a double quantum dot turnstile is, in principle, an efficient electron spin entangler or entanglement filter because of the exchange coupling between the dots and the tunable input/output potential barriers, provided certain conditions are satisfied in the experimental set-up.Comment: published version; minor error correcte

    Effects of decoherence and errors on Bell-inequality violation

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    We study optimal conditions for violation of the Clauser-Horne-Shimony-Holt form of the Bell inequality in the presence of decoherence and measurement errors. We obtain all detector configurations providing the maximal Bell inequality violation for a general (pure or mixed) state. We consider local decoherence which includes energy relaxation at the zero temperature and arbitrary dephasing. Conditions for the maximal Bell-inequality violation in the presence of decoherence are analyzed both analytically and numerically for the general case and for a number of important special cases. Combined effects of measurement errors and decoherence are also discussed.Comment: 18 pages, 5 figure
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