Staggered Chiral Perturbation Theory for Heavy-Light Mesons

We incorporate heavy-light mesons into staggered chiral perturbation theory, working to leading order in 1/m_Q, where m_Q is the heavy quark mass. At first non-trivial order in the chiral expansion, staggered taste violations affect the chiral logarithms for heavy-light quantities only through the light meson propagators in loops. There are also new analytic contributions coming from additional terms in the Lagrangian involving heavy-light and light mesons. Using this heavy-light staggered chiral perturbation theory, we perform the one-loop calculation of the B (or D) meson leptonic decay constant in the partially quenched and full QCD cases. In our treatment, we assume the validity both of the "fourth root trick" to reduce four staggered tastes to one, and of the prescription to represent this trick in the chiral theory by insertions of factors of 1/4 for each sea quark loop.Comment: 48 pages, 6 figures. v3: Some clarifying comments/caveats added; typos fixed. Corresponds to published versio

Analytic solutions of a simple advection-diffusion model of an oxygen transfer device

Artificial blood oxygenation is an essential aspect of cardiopulmonary bypass surgery, maintaining physiological levels of oxygen and carbon dioxide in the blood, and thus temporarily replacing the normal function of the lungs. The blood-gas exchange devices used for such procedures have a long history and have had varying degrees of success. In this paper we consider a simple model of a new approach to enhancing the diffusion of oxygen into the blood while it is contained in the artificial blood oxygenator. We show that using a transverse flow, which may be set up using mixing elements that we have previously shown experimentally to enhance blood oxygenation, will increase the oxygen levels within the blood. This simple model and associated analytic solutions can then be used to aid the optimisation of blood oxygenation devices

Heavy-Quark Symmetry and the Electromagnetic Decays of Excited Charmed Strange Mesons

Heavy-hadron chiral perturbation theory (HH$\chi$PT) is applied to the decays of the even-parity charmed strange mesons, D_{s0}(2317) and D_{s1}(2460). Heavy-quark spin symmetry predicts the branching fractions for the three electromagnetic decays of these states to the ground states D_s and D_s^* in terms of a single parameter. The resulting predictions for two of the branching fractions are significantly higher than current upper limits from the CLEO experiment. Leading corrections to the branching ratios from chiral loop diagrams and spin-symmetry violating operators in the HH$\chi$PT Lagrangian can naturally account for this discrepancy. Finally the proposal that the D_{s0}(2317) (D_{s1}(2460)) is a hadronic bound state of a D (D^*) meson and a kaon is considered. Leading order predictions for electromagnetic branching ratios in this molecular scenario are in very poor agreement with existing data.Comment: 25 pages, 3 figure

Exact Absorption Probability in the Extremal Six-Dimensional Dyonic String Background

We show that the minimally coupled massless scalar wave equation in the background of an six-dimensional extremal dyonic string (or D1-D5 brane intersection) is exactly solvable, in terms of Mathieu functions. Using this fact, we calculate absorption probabilities for these scalar waves, and present the explicit results for the first few low energy corrections to the leading-order expressions. For a specific tuning of the dyonic charges one can reach a domain where the low energy absorption probability goes to zero with inverse powers of the logarithm of the energy. This is a dividing domain between the regime where the low energy absorption probability approaches zero with positive powers of energy and the regime where the probability is an oscillatory function of the logarithm of the energy. By the conjectured AdS/CFT correspondence, these results shed novel light on the strongly coupled two-dimensional field theory away from its infrared conformally invariant fixed point (the strongly coupled ``non-critical'' string).Comment: Latex (3 times), 23 page

Excited B mesons from the lattice

We determine the energies of the excited states of a heavy-light meson $Q\bar{q}$, with a static heavy quark and light quark with mass approximately that of the strange quark from both quenched lattices and with dynamical fermions. We are able to explore the energies of orbital excitations up to L=3, the spin-orbit splitting up to L=2 and the first radial excitation. These $b \bar{s}$ mesons will be very narrow if their mass is less than 5775 MeV -- the $BK$ threshold. We investigate this in detail and present evidence that the scalar meson (L=1) will be very narrow and that as many as 6 $b \bar{s}$ excited states will have energies close to the $BK$ threshold and should also be relatively narrow.Comment: 17 pages, 6 ps figure

Waiting for Precise Measurements of K^+->pi^+ nu nu and K_L->pi^0 nu nu

In view of future plans for accurate measurements of the theoretically clean branching ratios Br(K+ -> pi+ nu nu) and Br(KL -> pi0 nu nu), that should take place in the next decade, we collect the relevant formulae for quantities of interest and analyze their theoretical and parametric uncertainties. We point out that in addition to the angle beta in the unitarity triangle (UT) also the angle gamma can in principle be determined from these decays with respectable precision and emphasize in this context the importance of the recent NNLO QCD calculation of the charm contribution to K+ -> pi+ nu nu and of the improved estimate of the long distance contribution by means of chiral perturbation theory. In addition to known expressions we present several new ones that should allow transparent tests of the Standard Model (SM) and of its extensions. While our presentation is centered around the SM, we also discuss models with minimal flavour violation and scenarios with new complex phases in decay amplitudes and meson mixing. We give a brief review of existing results within specific extensions of the SM, in particular the Littlest Higgs Model with T-parity, Z' models, the MSSM and a model with one universal extra dimension. We derive a new "golden" relation between B and K systems that involves (beta,gamma) and Br(KL -> pi0 nu nu) and investigate the virtues of (R_t,beta), (R_b,gamma), (beta,gamma) and (etabar,gamma) strategies for the UT in the context of K -> pi nu nu decays with the goal of testing the SM and its extensions.Comment: 56 pages, 18 figures, Section on Long Distance Contributions, 2 Figures and few References added, Uses Rev Mod Phys Style; Includes new results of NNLO calculation as well as matrix elements, extended and modified sections on new physic

‘Doing the right thing’: factors influencing GP prescribing of antidepressants and prescribed doses

Background: Antidepressant prescribing continues to increase, with 5-16% of adults receiving antidepressants annually. Total prescribing growth is due in part to increased long-term use, greater selective serotonin re-uptake inhibitor (SSRI) use and the use of higher SSRI doses. Evidence does not support routine use of higher SSRI doses for depression treatment, and factors influencing the use of such doses are not well known. The aim of this study was to explore factors influencing GPs’ use of antidepressants and their doses to treat depression.Methods: Semi-structured interviews with a purposive sample of 28 practising GPs; sampled by antidepressant prescribing volume, practice size and deprivation level. A topic guide drawing on past literature was used with enough flexibility to allow additional themes to emerge. Interviews were audio-recorded and transcribed verbatim.Framework analysis was employed. Constant comparison and disconfirmation were carried out across transcripts,with data collection being interspersed with analysis by three researchers. The thematic framework was thensystematically applied to the data and conceptualised into an overarching explanatory model.Results: Depression treatment involved ethical and professional imperatives of ‘doing the right thing’ for individuals by striving to achieve the ‘right care fit’. This involved medicalised and non-medicalised patient-centred approaches.Factors influencing antidepressant prescribing and doses varied over time from first presentation, to antidepressant initiation and longer-term treatment. When faced with distressed patients showing symptoms of moderate to severe depression GPs were confident prescribing SSRIs which they considered as safe and effective medicines, andethically and professionally appropriate.Many GPs were unaware that higher doses lacked greater efficacy and onset of action occurred within 1-2 weeks,preferring to wait 8-12 weeks before increasing or switching. Ongoing pressures to maintain prescribing (e.g. fear of depression recurrence), few perceived continuation problems (e.g. lack of safety concerns) and lack of proactive medication review (e.g. patients only present in crisis), all combine to further drive antidepressant prescribing growth over time.Conclusions: GPs strive to ‘do the right thing’ to help people. Antidepressants are only a single facet of depression treatment. However, increased awareness of drug limitations and regular proactive reviews may help optimise care

Excited Charmed Mesons: Observations, Analyses and Puzzles

We review the status of recently observed positive parity charmed resonances, both in the non-strange and in the strange sector. We describe the experimental findings, the main theoretical analyses and the open problems deserving further investigations.Comment: LaTeX, 25 pages, 5 figures. Invited revie

"I am your mother and your father!": In vitro derived gametes and the ethics of solo reproduction

In this paper, we will discuss the prospect of human reproduction achieved with gametes originating from only one person. According to statements by a minority of scientists working on the generation of gametes in vitro, it may become possible to create eggs from men’s non-reproductive cells and sperm from women’s. This would enable, at least in principle, the creation of an embryo from cells obtained from only one individual: ‘solo reproduction’. We will consider what might motivate people to reproduce in this way, and the implications that solo reproduction might have for ethics and policy. We suggest that such an innovation is unlikely to revolutionise reproduction and parenting. Indeed, in some respects it is less revolutionary than in vitro fertilisation as a whole. Furthermore, we show that solo reproduction with in vitro created gametes is not necessarily any more ethically problematic than gamete donation—and probably less so. Where appropriate, we draw parallels with the debate surrounding reproductive cloning. We note that solo reproduction may serve to perpetuate reductive geneticised accounts of reproduction, and that this may indeed be ethically questionable. However, in this it is not unique among other technologies of assisted reproduction, many of which focus on genetic transmission. It is for this reason that a ban on solo reproduction might be inconsistent with continuing to permit other kinds of reproduction that also bear the potential to strengthen attachment to a geneticised account of reproduction. Our claim is that there are at least as good reasons to pursue research towards enabling solo reproduction, and eventually to introduce solo reproduction as an option for fertility treatment, as there are to do so for other infertility related purposes

Depression, drugs and dental anxiety in prisons:A mediation model explaining dental decay experience

Funding: Scottish Government (award number: 121.804485) and support from the Scottish Prison Service and participating NHS Boards.Objective To test a theoretical mediation model and investigate whether drug use and/or dental anxiety act as mediating factors between depression and dental decay experience among prisoners. Method A cross‐sectional survey was conducted on a convenience sample of 300 prisoners across three prison establishments in Scotland. Depression and dental anxiety were measured using the Centre for Epidemiological Studies Depression Scale and the Modified Dental Anxiety Scale, respectively. Drug use was assessed using three yes (scoring 1)/ no (scoring 0) questions: ‘ever taken (illegal) drugs’, ‘injecting drugs’ and ‘ever participated in a rehabilitation programme’. Participants had an oral examination to determine dental caries experience (missing [MT] and untreated decay [D3cvT]) in all four quadrants. Latent variable path analysis was conducted to test the mediation model. Results A total of 342 prisoners participated, of which 298 yielded a complete data set. Depression was associated with missing teeth and untreated decay (D3T) through an indirect pathway (Total standardized indirect effects = 0.11, P < .01) via drug use and dental anxiety (X2 [71] = 89.8, P = .07; Root Mean Square Error of Approximation: 0.03; Comparative Fit Index: 0.994 and Tucker‐Lewis index: 0.992). Twenty‐two percent of the variance in untreated decay and missing teeth was explained by both drug use and dental anxiety; however, the strongest predictor was drug use (total standardized direct effects = 0.45, P < .001). Conclusion A relatively simple model to assist understanding dental decay experience of people in prison has been proposed. The data collected were consistent with our specified model. Drug use acted as the primary mediator and dental anxiety as a secondary mediator between depression and dental decay experience. Given the co‐morbidity between mental health and drug use and dental decay experience, an integrated or shared approach is proposed. We recommend that future research should concentrate on building a firmer picture by replicating and extending the framework presented.PostprintPeer reviewe