39,651 research outputs found

    The status of traditional Scottish animal breeds and plant varieties and the implications for biodiversity

    Get PDF
    The aim of this scoping study was to evaluate the effects on Scottish biodiversity of changes in the use of traditional breeds and varieties. The overall objectives were: a) The evaluation of the importance of genetic loss from the reduction in use of these breeds and varieties, for example, the loss of unusual characteristics that might have been of particular local use. b) An assessment of the impacts of reduction in the ability to conduct further breeding or research on rare and traditional varieties and breeds. c) Identification of the loss of certain farming techniques associated with particular varieties and breeds. d) An assessment of possible losses of biodiversity associated with reduction in the use of these breeds and varieties and the farming systems associated with them

    Condensate splitting in an asymmetric double well for atom chip based sensors

    Full text link
    We report on the adiabatic splitting of a BEC of 87^{87}Rb atoms by an asymmetric double-well potential located above the edge of a perpendicularly magnetized TbGdFeCo film atom chip. By controlling the barrier height and double-well asymmetry the sensitivity of the axial splitting process is investigated through observation of the fractional atom distribution between the left and right wells. This process constitutes a novel sensor for which we infer a single shot sensitivity to gravity fields of δg/g≈2×10−4\delta g/g\approx2\times10^{-4}. From a simple analytic model we propose improvements to chip-based gravity detectors using this demonstrated methodology.Comment: 4 pages, 5 figure

    Threshold Corrections in the Exceptional Supersymmetric Standard Model

    Get PDF
    We calculate threshold corrections to the running gauge and Yukawa couplings in the Exceptional Supersymmetric Standard Model (E6SSM) and analyse the more precise and reliable mass spectra in a constrained model (CE6SSM). Full expressions for the corrections are provided and the implementation into a spectrum generator is described. We find a dramatic reduction in the matching scale dependency of the masses of many states and observe a significant adjustment of the correlation of low-scale physical masses and high-scale parameters. Still, in substantial regions of parameter space the mass of the lightest Higgs is compatible with the new boson discovered at the LHC and the model satisfies limits from collider searches for squark, gluinos and Z' bosons. We study the implications for gauge coupling unification from a new dependency of the spectrum on so-called survival Higgs fields which cannot be addressed without the inclusion of the threshold corrections.Comment: 59 pages, 25 figures, v2 fixed typo and rephrased parts of section 5.3.1, v2 accepted for publication in Physical Review

    Effect of Magnetization Inhomogeneity on Magnetic Microtraps for Atoms

    Get PDF
    We report on the origin of fragmentation of ultracold atoms observed on a permanent magnetic film atom chip. A novel technique is used to characterize small spatial variations of the magnetic field near the film surface using radio frequency spectroscopy of the trapped atoms. Direct observations indicate the fragmentation is due to a corrugation of the magnetic potential caused by long range inhomogeneity in the film magnetization. A model which takes into account two-dimensional variations of the film magnetization is consistent with the observations.Comment: 4 pages, 4 figure

    Precision measurements of s-wave scattering lengths in a two-component Bose-Einstein condensate

    Full text link
    We use collective oscillations of a two-component Bose-Einstein condensate (2CBEC) of \Rb atoms prepared in the internal states ∣1⟩≡∣F=1,mF=−1⟩\ket{1}\equiv\ket{F=1, m_F=-1} and ∣2⟩≡∣F=2,mF=1⟩\ket{2}\equiv\ket{F=2, m_F=1} for the precision measurement of the interspecies scattering length a12a_{12} with a relative uncertainty of 1.6×10−41.6\times 10^{-4}. We show that in a cigar-shaped trap the three-dimensional (3D) dynamics of a component with a small relative population can be conveniently described by a one-dimensional (1D) Schr\"{o}dinger equation for an effective harmonic oscillator. The frequency of the collective oscillations is defined by the axial trap frequency and the ratio a12/a11a_{12}/a_{11}, where a11a_{11} is the intra-species scattering length of a highly populated component 1, and is largely decoupled from the scattering length a22a_{22}, the total atom number and loss terms. By fitting numerical simulations of the coupled Gross-Pitaevskii equations to the recorded temporal evolution of the axial width we obtain the value a12=98.006(16) a0a_{12}=98.006(16)\,a_0, where a0a_0 is the Bohr radius. Our reported value is in a reasonable agreement with the theoretical prediction a12=98.13(10) a0a_{12}=98.13(10)\,a_0 but deviates significantly from the previously measured value a12=97.66 a0a_{12}=97.66\,a_0 \cite{Mertes07} which is commonly used in the characterisation of spin dynamics in degenerate \Rb atoms. Using Ramsey interferometry of the 2CBEC we measure the scattering length a22=95.44(7) a0a_{22}=95.44(7)\,a_0 which also deviates from the previously reported value a22=95.0 a0a_{22}=95.0\,a_0 \cite{Mertes07}. We characterise two-body losses for the component 2 and obtain the loss coefficients γ12=1.51(18)×10−14cm3/s{\gamma_{12}=1.51(18)\times10^{-14} \textrm{cm}^3/\textrm{s}} and γ22=8.1(3)×10−14cm3/s{\gamma_{22}=8.1(3)\times10^{-14} \textrm{cm}^3/\textrm{s}}.Comment: 11 pages, 8 figure

    Aircraft control via variable cant-angle winglets

    Get PDF
    Copyright @ 2008 American Institute of Aeronautics and AstronauticsThis paper investigates a novel method for the control of "morphing" aircraft. The concept consists of a pair of winglets; with adjustable cant angle, independently actuated and mounted at the tips of a baseline flying wing. The general philosophy behind the concept was that for specific flight conditions such as a coordinated turn, the use of two control devices would be sufficient for adequate control. Computations with a vortex lattice model and subsequent wind-tunnel tests demonstrate the viability of the concept, with individual and/or dual winglet deflection producing multi-axis coupled control moments. Comparisons between the experimental and computational results showed reasonable to good agreement, with the major discrepancies thought to be due to wind-tunnel model aeroelastic effects.This work has been supported by a Marie Curie excellence research grant funded by the European Commission

    Cluster-assisted accretion for massive stars

    Get PDF
    Gravitational interactions in very young high-density stellar clusters can to some degree change the angular momentum in the circumstellar discs surrounding initially the majority of stars. However, for most stars the cluster environment alters the angular momentum only slightly. For example, in simulations of the Orion Nebula cluster (ONC) encounters reduce the angular momentum of the discs on average at most by 3-5% and in the higher density region of the Trapezium %where encounters are more likely, the disc angular momentum is on average lowered by 15-20% - still a minor loss process. However, in this paper it is demonstrated that the situation is very different if one considers high-mass stars (M* > 10 M(solar) only. Assuming an age of 2 Myr for the ONC, their discs have on average a 50-90% lower angular momentum than primordially. This enormous loss in angular momentum in the disc should result in an equivalent increase in accretion, implying that the cluster environment boosts accretion for high-mass stars, thus %in the cluster center, making them even more massive.Comment: 10 pages including 2 figures, accepted for publication in ApJ

    Renormalization--Group Solutions for Yukawa Potential

    Full text link
    The self--similar renormalization group is used to obtain expressions for the spectrum of the Hamiltonian with the Yukawa potential. The critical screening parameter above which there are no bound states is also obtained by this method. The approach presented illustrates that one can achieve good accuracy without involving extensive numerical calculations, but invoking instead the renormalization--group techniques.Comment: 1 file, 12 pages, RevTe

    An audit of the quality of inpatient care for adults with learning disability in the UK

    Get PDF
    OBJECTIVES: To audit patient hospital records to evaluate the performance of acute general and mental health services in delivering inpatient care to people with learning disability and explore the influence of organisational factors on the quality of care they deliver. SETTING: Nine acute general hospital Trusts and six mental health services. PARTICIPANTS: Adults with learning disability who received inpatient hospital care between May 2013 and April 2014. PRIMARY AND SECONDARY OUTCOME MEASURES: Data on seven key indicators of high-quality care were collected from 176 patients. These covered physical health/monitoring, communication and meeting needs, capacity and decision-making, discharge planning and carer involvement. The impact of services having an electronic system for flagging patients with learning disability and employing a learning disability liaison nurse was assessed. RESULTS: Indicators of physical healthcare (body mass index, swallowing assessment, epilepsy risk assessment) were poorly recorded in acute general and mental health inpatient settings. Overall, only 34 (19.3%) patients received any assessment of swallowing and 12 of the 57 with epilepsy (21.1%) had an epilepsy risk assessment. For most quality indicators, there was a non-statistically significant trend for improved performance in services with a learning disability liaison nurse. The presence of an electronic flagging system showed less evidence of benefit. CONCLUSIONS: Inpatient care for people with learning disability needs to be improved. The work gives tentative support to the role of a learning disability liaison nurse in acute general and mental health services, but further work is needed to confirm these benefits and to trial other interventions that might improve the quality and safety of care for this high-need group

    Unravelling quantum carpets: a travelling wave approach

    Get PDF
    Quantum carpets are generic spacetime patterns formed in the probability distributions P(x,t) of one-dimensional quantum particles, first discovered in 1995. For the case of an infinite square well potential, these patterns are shown to have a detailed quantitative explanation in terms of a travelling-wave decomposition of P(x,t). Each wave directly yields the time-averaged structure of P(x,t) along the (quantised)spacetime direction in which the wave propagates. The decomposition leads to new predictions of locations, widths depths and shapes of carpet structures, and results are also applicable to light diffracted by a periodic grating and to the quantum rotator. A simple connection between the waves and the Wigner function of the initial state of the particle is demonstrated, and some results for more general potentials are given.Comment: Latex, 26 pages + 6 figures, submitted to J. Phys. A (connections with prior literature clarified
    • …
    corecore