1,021 research outputs found

    Reducing the use of inhaled corticosteroids in mild-moderate COPD: an observational study in east London

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    Inhaled corticosteroids (ICS) are often prescribed for worsening breathlessness, exacerbation frequency or lung function in chronic obstructive pulmonary disease (COPD). In mild-moderate disease and infrequent exacerbations, treatment risks may outweigh benefits and ICS may be withdrawn safely under supervision. A systematic ICS deprescribing programme for patients with mild-moderate COPD was introduced in an east London Clinical Commissioning Group (CCG) in April 2017. Primary care patient record analysis found that prescribing fell from 34.9% (n = 701) in the 18 months pre-intervention to 26.9% (n = 538) by the second year of implementation, decreasing 0.84% per quarter post intervention (p = 0.006, linear regression). The relative decrease was greater than the comparison CCG (23.0% vs. 9.9%). Only South Asian ethnicity was associated with increased cessation (odds ratio 1.48, confidence interval (CI) 1.09-2.01), p = 0.013, logistic regression). Patient outcome data were not collected. A primary care-led programme comprising local education, financial incentivisation and consultant support led to a significant decrease in ICS prescribing

    Heterotic type IIA duality with fluxes - towards the complete story

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    In this paper we study the heterotic type IIA duality when fluxes are turned on. We show that many of the known fluxes are dual to each other and claim that certain fluxes on the heterotic side require that the type IIA picture is lifted to M or even F-theory compactifications with geometric fluxes.Comment: 31 pages, references adde

    Double Field Theory Formulation of Heterotic Strings

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    We extend the recently constructed double field theory formulation of the low-energy theory of the closed bosonic string to the heterotic string. The action can be written in terms of a generalized metric that is a covariant tensor under O(D,D+n), where n denotes the number of gauge vectors, and n additional coordinates are introduced together with a covariant constraint that locally removes these new coordinates. For the abelian subsector, the action takes the same structural form as for the bosonic string, but based on the enlarged generalized metric, thereby featuring a global O(D,D+n) symmetry. After turning on non-abelian gauge couplings, this global symmetry is broken, but the action can still be written in a fully O(D,D+n) covariant fashion, in analogy to similar constructions in gauged supergravities.Comment: 28 pages, v2: minor changes, version published in JHE

    Flux moduli stabilisation, Supergravity algebras and no-go theorems

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    We perform a complete classification of the flux-induced 12d algebras compatible with the set of N=1 type II orientifold models that are T-duality invariant, and allowed by the symmetries of the T^6/(Z_2 x Z_2) isotropic orbifold. The classification is performed in a type IIB frame, where only H_3 and Q fluxes are present. We then study no-go theorems, formulated in a type IIA frame, on the existence of Minkowski/de Sitter (Mkw/dS) vacua. By deriving a dictionary between the sources of potential energy for the three moduli (S, T and U) in types IIA and IIB, we are able to combine algebra results and no-go theorems. The outcome is a systematic procedure for identifying phenomenologically viable models where Mkw/dS vacua may exist. We present a complete table of the allowed algebras and the viability of their resulting scalar potential, and we point at the models which stand any chance of producing a fully stable vacuum.Comment: Version published in JHE

    A Waveguide Based Acoustic Microscope with Application to the Evaluation of Bone

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    A new ultrasonic scanning system has been developed which is capable of accurate velocity measurements with high spatial resolution. This performance is achieved while using relatively low frequencies to minimize the cost of the instrument. A waveguide detector is used in place of the normal focused ultrasonic transducer. The waveguide receiver makes it possible to provide the needed spatial resolution without limitations imposed by the finite aperture of the transducer. An increase in the complexity of the signal processing required and reduced throughput of the instrument results from this approach. However, these disadvantages are amply compensated by the ability to investigate materials with high attenuation and low wave velocities. These measurements are not possible with traditional acoustic microscopes

    Double Field Theory for Double D-branes

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    We consider Hull's doubled formalism for open strings on D-branes in flat space and construct the corresponding effective double field theory. We show that the worldsheet boundary conditions of the doubled formalism describe in a unified way a T-dual pair of D-branes, which we call double D-branes. We evaluate the one-loop beta function for the boundary gauge coupling and then obtain the effective field theory for the double D-branes. The effective field theory is described by a DBI action of double fields. The T-duality covariant form of this DBI action is thus a kind of "master" action, which describes all the double D-brane configurations related by T-duality transformations. We discuss a number of aspects of this effective theory.Comment: Latex, 1+33 pages. v2 with minor corrections, a new reference added. v3 a typo correcte

    Digital Measurement of Ultrasonic Velocity

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    The ultrasonic material evaluation has been applied to composite materials and nonhomogeneous materials. In quantitative evaluation of these materials the ultrasonic velocity and attenuation are widely used. In addition acoustoelastic stress measurement requires high precision measurement of the ultrasonic velocity

    A ten-dimensional action for non-geometric fluxes

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    The NSNS Lagrangian of ten-dimensional supergravity is rewritten via a change of field variables inspired by Generalized Complex Geometry. We obtain a new metric and dilaton, together with an antisymmetric bivector field which leads to a ten-dimensional version of the non-geometric Q-flux. Given the involved global aspects of non-geometric situations, we prescribe to use this new Lagrangian, whose associated action is well-defined in some examples investigated here. This allows us to perform a standard dimensional reduction and to recover the usual contribution of the Q-flux to the four-dimensional scalar potential. An extension of this work to include the R-flux is discussed. The paper also contains a brief review on non-geometry.Comment: 47 pages; v2: minor modifications, references added, version to be published in JHE

    Temporal dynamics of aquatic communities and implications for pond conservation

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    Conservation through the protection of particular habitats is predicated on the assumption that the conservation value of those habitats is stable. We test this assumption for ponds by investigating temporal variation in macroinvertebrate and macrophyte communities over a 10-year period in northwest England. We surveyed 51 ponds in northern England in 1995/6 and again in 2006, identifying all macrophytes (167 species) and all macroinvertebrates (221 species, excluding Diptera) to species. The alpha-diversity, beta-diversity and conservation value of these ponds were compared between surveys. We find that invertebrate species richness increased from an average of 29. 5 species to 39. 8 species between surveys. Invertebrate gamma-diversity also increased between the two surveys from 181 species to 201 species. However, this increase in diversity was accompanied by a decrease in beta-diversity. Plant alpha-, beta and gamma-diversity remained approximately constant between the two periods. However, increased proportions of grass species and a complete loss of charophytes suggests that the communities are undergoing succession. Conservation value was not correlated between sampling periods in either plants or invertebrates. This was confirmed by comparing ponds that had been disturbed with those that had no history of disturbance to demonstrate that levels of correlation between surveys were approximately equal in each group of ponds. This study has three important conservation implications: (i) a pond with high diversity or high conservation value may not remain that way and so it is unwise to base pond conservation measures upon protecting currently-speciose habitats; (ii) maximising pond gamma-diversity requires a combination of late and early succession ponds, especially for invertebrates; and (iii) invertebrate and plant communities in ponds may require different management strategies if succession occurs at varying rates in the two groups
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