5,113 research outputs found

    Jaynes Cummings treatment of superconducting resonators with dielectric loss due to two-level systems

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    We perform a quantum mechanical analysis of superconducting resonators subject to dielectric loss arising from charged two-level systems. We present numerical and analytical descriptions of the dynamics of energy decay from the resonator within the Jaynes-Cummings model. Our analysis allows us to distinguish the strong and weak coupling regimes of the model and to describe within each regime cases where the two-level system is unsaturated or saturated. We find that the quantum theory agrees with the classical model for weak coupling. However, for strong coupling the quantum theory predicts lower loss than the classical theory in the unsaturated regime. Also, in contrast to the classical theory, the photon number at which saturation occurs in the strong coupling quantum theory is independent of the coupling between the resonator and the two-level system.Comment: 9 pages, 8 figure

    Frequency-Tunable Josephson Junction Resonator for Quantum Computing

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    We have fabricated and measured a high-Q Josephson junction resonator with a tunable resonance frequency. A dc magnetic flux allows the resonance frequency to be changed by over 10 %. Weak coupling to the environment allows a quality factor of ∼\thicksim7000 when on average less than one photon is stored in the resonator. At large photon numbers, the nonlinearity of the Josephson junction creates two stable oscillation states. This resonator can be used as a tool for investigating the quality of Josephson junctions in qubits below the single photon limit, and can be used as a microwave qubit readout at high photon numbers.Comment: 3 pages, 5 figure

    Empirical Determination of Nuclear Moments of Inertia and Intrinsic Quadrupole Moments

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86148/1/PhysRev.103.833-RKO.pd

    Oocyte cryopreservation as an adjunct to the assisted reproductive technologies

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    The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included. See page 2 of PDF for this item.Keith L Harrison, Michelle T Lane, Jeremy C Osborn, Christine A Kirby, Regan Jeffrey, John H Esler and David Mollo

    Empirical Correlation of Nuclear Magnetic Moments

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    A simple generalization of the extreme shell model, based upon the kinematics of the collective model, is proposed for the correlation of nuclear magnetic moments. It is shown that, if the concept of a rotating core is adjoined to that of the single-particle model, largely in disregard of dynamical considerations, then by the aid of three simple empirical rules ground-state wave functions may be easily constructed which correctly express the parities, spins, and magnetic moments of all nuclei for which A>~7, with the exception of W183. ** The choice of a particular set of empirical rules was dictated primarily by the twofold desire to keep their number to a minimum and at the same time restrict the consequent wave function to but two components; hence, considerable oversimplification of the true state of affairs is inevitable. However, the internal consistency of the results does point up strikingly the previously observed, but not explicitly investigated, possibility that the nature of the variable degrees of freedom required for generalization of the single-particle model may differ fundamentally for j=l+1/2 in contrast to j=l-1/2 single-particle configurationsÑbeing predominantly those of the core in the former instance and those of the single particle in the latter.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86147/1/PhysRev.100.822-RKO.pd

    Myogenesis in the mouse embryo: Differential onset of expression of myogenic proteins and the involvement of titin in myofibril assembly.

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    Antibodies to muscle-specific proteins were used in immunofluorescence to monitor the development of skeletal muscle during mouse embryogenesis. At gestation day (g.d.) 9 a single layer of vimentin filament containing cells in the myotome domain of cervical somites begins to stain positively for myogenic proteins. The muscle-specific proteins are expressed in a specific order between g.d. 9 and 9.5. Desmin is detected first, then titin, then the muscle specific actin and myosin heavy chains, and finally nebulin. At g.d. 9.5 fibrous desmin structures are already present, while for the other myogenic proteins no structure can be detected. Some prefusion myoblasts display at g.d. 11 and 12 tiny and immature myofibrils. These reveal a periodic pattern of myosin, nebulin, and those titin epitopes known to occur at and close to the Z line. In contrast titin epitopes, which are present in mature myofibrils along the A band and at the A-I junction, are still randomly distributed. We propose, that the Z line connected structures and the A bands (myosin filaments) assemble independently, and that the known interaction of the I-Z-I brushes with the A bands occurs at a later developmental stage. After fusion of myoblasts to myotubes at g.d. 13 and 14 all titin epitopes show the myofibrillar banding pattern. The predominantly longitudinal orientation of desmin filaments seen in myoblasts and in early myotubes is transformed at g.d. 17 and 18 to distinct Z line connected striations. Vimentin, still present together with desmin in the myoblasts, is lost from the myotubes. Our results indicate that the putative elastic titin filaments act as integrators during skeletal muscle development. Some developmental aspects of eye and limb muscles are also described

    Is there an association between perceived social support and cardiovascular health behaviours in people with severe mental illnesses?

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    PURPOSE: People with severe mental illnesses (SMI) have an increased risk of cardiovascular disease (CVD). Research in the general population suggests that social support may protect against increased CVD morbidity and mortality; however, this may not apply to those with SMI. We aimed to explore the association between perceived social support and attendance at primary care nurse CVD risk reduction clinic appointments and CVD risk-reducing behaviours in an SMI population with elevated CVD risk factors. METHODS: We used longitudinal and cross-sectional data from a randomised controlled trial on 326 adults with SMI recruited via 76 general practices in England. Multilevel regression analysis estimated the effect of perceived social support on attendance at CVD risk reduction clinic appointments over 6 months, and adherence to CVD medication, physical activity, diet, smoking and alcohol use at baseline, adjusted by age, sex, ethnicity, deprivation, psychiatric diagnosis and employment. RESULTS: Perceived social support predicted greater appointment attendance in unadjusted (IRR = 1.005; 1.000-1.010; p = 0.05) but not adjusted analysis (IRR = 1.003; 0.998-1.009; p = 0.25). Perceived social support was associated with greater adherence to medication; for each 1% increase in social support, there was a 4.2% increase in medication adherence (OR = 1.042; 1.015-1.070; p = 0.002). No association was found between greater perceived social support and greater physical activity, lower sedentary behaviour, healthier diet, lower alcohol use or being a non-smoker. CONCLUSIONS: Social support may be an important facilitator for CVD medication adherence and is potentially important for primary care appointment attendance; however, alternative strategies might be needed to help people with SMI engage in physical activity, healthier diets and to reduce their smoking and alcohol use
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