535 research outputs found

    The Working in Health Access Programme (WHAP): impact on school leaving exam results and applications to Medicine

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    Introduction: Pupils from backgrounds wit socio-economic deprivation are less likely to apply to study medicine than those from more affluent backgrounds. It is unclear whether those who might have the potential to be doctors can be identified at a time when they can be exposedto awareness raising activities to enhance their likelihood of success. Methods: Sixty nine schools from all parts of Scotland with below average participation rates in Higher Education took part. More than 2000 pupils sat tests of cognitive ability (Mill Hill Vocabulary Scale and Raven’s Progressive Matrices) as well as non-cognitive tests assessing characteristics that could influence success as a doctor. Results: The results of the cognitive tests correlated closely with Standard Grade Examinations (sat in Year 11) and less so with Highers (sat in Year 12). The numbers applying to and being admitted to Medicine rose 80% and 300% respectively over the duration of the project. Those receiving an offer differed in personality from those who didn’t. Discussion: Widening Participation activities of the type used in our project successfully increased application and offers for Medicine. The value of psychometric tests in the context of Widening Participation requires further research

    Phosphorylation of survivin at threonine 34 inhibits its mitotic function and enhances its cytoprotective activity

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    Survivin is an essential chromosomal passenger protein required for mitotic progression. It is also an inhibitor of apoptosis and can prevent caspase-mediated cell death. In addition, survivin levels are elevated in cancer cells where its presence correlates with increased resistance to chemo- and radio-therapy, which makes it an attractive target for novel anti-cancer strategies. Interestingly, survivin is phosphorylated by the mitotic kinase, cdk1, and a non-phosphorylatable form, survivin(T34A), cannot inhibit apoptosis. Here we rigorously test the ability of survivin(T34A) and its corresponding phosphomimetic, survivin(T34E), to promote cell viability through survivin's dual roles. The effects of these mutations are diametrically opposed: survivin(T34A) accelerates cell proliferation and promotes apoptosis, whereas survivin(T34E) retards growth and promotes survival. Thus the phosphorylation status of survivin at T34 is pivotal to a cell's decision to live or die

    On the practicality of time-optimal two-qubit Hamiltonian simulation

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    What is the time-optimal way of using a set of control Hamiltonians to obtain a desired interaction? Vidal, Hammerer and Cirac [Phys. Rev. Lett. 88 (2002) 237902] have obtained a set of powerful results characterizing the time-optimal simulation of a two-qubit quantum gate using a fixed interaction Hamiltonian and fast local control over the individual qubits. How practically useful are these results? We prove that there are two-qubit Hamiltonians such that time-optimal simulation requires infinitely many steps of evolution, each infinitesimally small, and thus is physically impractical. A procedure is given to determine which two-qubit Hamiltonians have this property, and we show that almost all Hamiltonians do. Finally, we determine some bounds on the penalty that must be paid in the simulation time if the number of steps is fixed at a finite number, and show that the cost in simulation time is not too great.Comment: 9 pages, 2 figure

    Landau Damping and Coherent Structures in Narrow-Banded 1+1 Deep Water Gravity Waves

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    We study the nonlinear energy transfer around the peak of the spectrum of surface gravity waves by taking into account nonhomogeneous effects. In the narrow-banded approximation the kinetic equation resulting from a nonhomogeneous wave field is a Vlasov-Poisson type equation which includes at the same time the random version of the Benjamin-Feir instability and the Landau damping phenomenon. We analytically derive the values of the Phillips' constant α\alpha and the enhancement factor γ\gamma for which the narrow-banded approximation of the JONSWAP spectrum is unstable. By performing numerical simulations of the nonlinear Schr\"{o}dinger equation we check the validity of the prediction of the related kinetic equation. We find that the effect of Landau damping is to suppress the formation of coherent structures. The problem of predicting freak waves is briefly discussed.Comment: 4 pages, 3 figure

    Entanglement in the quantum Ising model

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    We study the asymptotic scaling of the entanglement of a block of spins for the ground state of the one-dimensional quantum Ising model with transverse field. When the field is sufficiently strong, the entanglement grows at most logarithmically in the number of spins. The proof utilises a transformation to a model of classical probability called the continuum random-cluster model, and is based on a property of the latter model termed ratio weak-mixing. Our proof applies equally to a large class of disordered interactions

    A new family of matrix product states with Dzyaloshinski-Moriya interactions

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    We define a new family of matrix product states which are exact ground states of spin 1/2 Hamiltonians on one dimensional lattices. This class of Hamiltonians contain both Heisenberg and Dzyaloshinskii-Moriya interactions but at specified and not arbitrary couplings. We also compute in closed forms the one and two-point functions and the explicit form of the ground state. The degeneracy structure of the ground state is also discussed.Comment: 15 pages, 1 figur

    Higher order parametric X-ray spectra in mosaic graphite and single silicon crystals

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    We have observed up to eight orders (n) in the spectra of parametric x-radiation, in the range 5-40 keV, produced by the interaction of a 90 Mev electron beam with mosaic graphite and 90 and 35 Mev beams with single silicon crystals. The measured yields and intensity ratios, I(2)/I(n= I), in graphite are not in agreement with the theory of PXR for mosaic crystals. In comparison, the yield and ratios of intensities in silicon are close to the predictions of PXR theory for perfect crystals. The bandwidths of spectral lines measured in both silicon and graphite are in good agreement with theoretical predictions, and are determined by the angular field of view of the detector.U.S. Department of EnergyDNANaval Postgraduate SchoolContract No. DE-FG03-91ER8109

    An entanglement monotone derived from Grover's algorithm

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    This paper demonstrates that how well a state performs as an input to Grover's search algorithm depends critically upon the entanglement present in that state; the more entanglement, the less well the algorithm performs. More precisely, suppose we take a pure state input, and prior to running the algorithm apply local unitary operations to each qubit in order to maximize the probability P_max that the search algorithm succeeds. We prove that, for pure states, P_max is an entanglement monotone, in the sense that P_max can never be decreased by local operations and classical communication.Comment: 7 page

    A short proof of stability of topological order under local perturbations

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    Recently, the stability of certain topological phases of matter under weak perturbations was proven. Here, we present a short, alternate proof of the same result. We consider models of topological quantum order for which the unperturbed Hamiltonian H0H_0 can be written as a sum of local pairwise commuting projectors on a DD-dimensional lattice. We consider a perturbed Hamiltonian H=H0+VH=H_0+V involving a generic perturbation VV that can be written as a sum of short-range bounded-norm interactions. We prove that if the strength of VV is below a constant threshold value then HH has well-defined spectral bands originating from the low-lying eigenvalues of H0H_0. These bands are separated from the rest of the spectrum and from each other by a constant gap. The width of the band originating from the smallest eigenvalue of H0H_0 decays faster than any power of the lattice size.Comment: 15 page

    Entanglement study of the 1D Ising model with Added Dzyaloshinsky-Moriya interaction

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    We have studied occurrence of quantum phase transition in the one-dimensional spin-1/2 Ising model with added Dzyaloshinsky-Moriya (DM) interaction from bi- partite and multi-partite entanglement point of view. Using exact numerical solutions, we are able to study such systems up to 24 qubits. The minimum of the entanglement ratio R ≡\equiv \tau 2/\tau 1 < 1, as a novel estimator of QPT, has been used to detect QPT and our calculations have shown that its minimum took place at the critical point. We have also shown both the global-entanglement (GE) and multipartite entanglement (ME) are maximal at the critical point for the Ising chain with added DM interaction. Using matrix product state approach, we have calculated the tangle and concurrence of the model and it is able to capture and confirm our numerical experiment result. Lack of inversion symmetry in the presence of DM interaction stimulated us to study entanglement of three qubits in symmetric and antisymmetric way which brings some surprising results.Comment: 18 pages, 9 figures, submitte
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