Experimental fitting to the bipolaronic model of the normal-state resistance of Bi_2Sr_2CaCu_2O_8 single crystals

Normal-state resistance data from Bi_2Sr_2CaCu_2O_8 single crystals were fitted to the (bi)polaronic conduction model, $R=R_0 (T+\sigma_b T^2)/(1+bT)$, with satisfactory agreement over a wide temperature range. The fluctuating conduction region is found to be much narrower than that in the usual sense, as is the case for a charged Bose-gas. We estimate the effective (bi)polaron mass to be ~ 4m_e.Comment: 2 pages + 2 postscript figures. Submitted to M2S-HTSC-VI(Houston) Conferenc

Lung function and respiratory symptoms in a 1-year randomized smoking cessation trial of varenicline in COPD patients

SummaryThere are few data concerning changes in lung function and respiratory symptoms in smokers with chronic obstructive pulmonary disease (COPD) weeks to months after quitting smoking. We examined serial changes in spirometry and Clinical COPD Questionnaire (CCQ) scores (measuring respiratory symptoms and health-related quality of life) in COPD participants by smoking status during a smoking cessation trial.In this randomized, double-blind trial, smokers with mild-to-moderate COPD were treated with varenicline 1 mg b.i.d. or placebo for 12 weeks and followed to Week 52. Primary endpoints of abstinence were previously reported. Secondary endpoints were mean changes from baseline in post-bronchodilator forced expired volume in 1 s (FEV1) and CCQ scores.Change from baseline in post-bronchodilator FEV1 was significantly improved in continuous abstainers (121.8 mL) vs. continuous smokers (37.9 mL) at Week 12 (P = 0.0069), but not at Weeks 24 or 52. Mean change from baseline at Week 12 in CCQ Total Score was significantly better in continuous abstainers (−1.04) vs. continuous smokers (−0.53; P < 0.0001): this improvement was sustained at Weeks 24 and 52.In a 1-year cessation trial of smokers with COPD, continuous abstinence compared with continuous smoking significantly improved post-bronchodilator FEV1 at Week 12 (although the difference narrowed subsequently) and CCQ Total Scores at Week 12, with sustained improvement thereafter.(Trial registry: http://www.clinicaltrials.gov; trial identifier: NCT00285012

Chinese adzuki bean germplasm: 1. Evaluation of agronomic traits

A core collection of adzuki beans, representing the germplasm of Chinese land races, was screened at Warwick Australia in a replicated yield trial sown mid-summer. Grain yield, yield components, phenologic traits, vegetative characteristics, and morphologic descriptors were recorded for all accessions plus Japanese-derived check varieties. Accessions from southern China were later flowering, had smaller seed, and grew taller than those from central China. Grain yield was greatest for accessions from central China, whereas both north Chinese and Japanese check accessions were generally low yielding. The evaluation of diversity displayed trends associated with latitude of germplasm origin, which were positive or negative according to the trait. Similarly, the germplasm diversity in duration of crop growth phases and in rate of yield expression was also associated with latitude of landrace origin. Localised variations from these trends were found for seed size and for number of pods per plant. Various trends with latitude of origin were found for natural incidence of powdery mildew, for growth habit, plant height, vining and leaf colour. However, traits not associated with latitude of germplasm origin included primary and secondary seed colour, mature pod colour, and degree of branching. The evaluation suggests that selections from this greater range of genetic diversity may allow higher yielding varieties than the current Japanese-derived standards to be developed for Australia

Supersymmetric Boost on Intersecting D-branes

We study the effect of the Born-Infeld electric field on the supersymmetric configuration of various composite D-branes. We show that the generic values of the electric field do not affect the supersymmetry but, as it approaches $1/2\pi\alpha'$ keeping the magnetic field finite, various combinations of the magnetic fields allow up to 8 supersymmetries. We also explore the unbroken supersymmetries for two intersecting D-strings which are in uniform or relative motion. For a finite uniform Lorentz boost, 16 supersymmetries are guaranteed only when they are parallel. For an infinite one, 8 supersymmetries are preserved only when both the D-strings are oriented to the forward or backward direction of the boost. Under a finite relative boost, 8 supersymmetries are preserved only when the intersecting angle is less than $\pi/2$ and the intersecting point moves at the speed of light. As for an infinite relative boost, 8 supersymmetries are preserved regardless of the values of the intersecting angle.Comment: 27 pages using REVTeX4, 7 figure

Towards reduction of type II theories on SU(3) structure manifolds

We revisit the reduction of type II supergravity on SU(3) structure manifolds, conjectured to lead to gauged N=2 supergravity in 4 dimensions. The reduction proceeds by expanding the invariant 2- and 3-forms of the SU(3) structure as well as the gauge potentials of the type II theory in the same set of forms, the analogues of harmonic forms in the case of Calabi-Yau reductions. By focussing on the metric sector, we arrive at a list of constraints these expansion forms should satisfy to yield a base point independent reduction. Identifying these constraints is a first step towards a first-principles reduction of type II on SU(3) structure manifolds.Comment: 20 pages; v2: condition (2.13old) on expansion forms weakened, replaced by (2.13new), (2.14new

Branes on Generalized Calibrated Submanifolds

We extend previous results on generalized calibrations to describe supersymmetric branes in supergravity backgrounds with diverse fields turned on, and provide several new classes of examples. As an important application, we show that supersymmetric D-branes in compactifications with field strength fluxes, and on SU(3)-structure spaces, wrap generalized calibrated submanifolds, defined by simple conditions in terms of the underlying globally defined, but non-closed, 2- and 3-forms. We provide examples where the geometric moduli of D-branes (for instance D7-branes in 3-form flux configurations) are lifted by the generalized calibration condition. In addition, we describe supersymmetric D6-branes on generalized calibrated 3-submanifolds of half-flat manifolds, which provide the mirror of B-type D-branes in IIB CY compactifications with 3-form fluxes. Supersymmetric sets of such D-branes carrying no homology charges are mirror to supersymmetric sets of D-branes which are homologically non-trivial, but trivial in K-theory. As an additional application, we describe models with chiral gauge sectors, realized in terms of generalized calibrated brane box configurations of NS- and D5-branes, which are supersymmetric but carry no charges, so that no orientifold planes are required in the compactification.Comment: 40 pages, 3 figures, references adde

The transfer of fibres in the carding machine

The problem of understanding the transfer of fibres between carding-machine surfaces is addressed by considering the movement of a single fibre in an airflow. The structure of the aerodynamic flow field predicts how and when fibres migrate between the different process surfaces. In the case of a revolving-flats carding machine the theory predicts a “strong” aerodynamic mechanism between taker-in and cylinder and a “weak” mechanism between cylinder and removal cylinder resulting in effective transfer in the first case and a more limited transfer in the second

From Fake Supergravity to Superstars

The fake supergravity method is applied to 5-dimensional asymptotically AdS spacetimes containing gravity coupled to a real scalar and an abelian gauge field. The motivation is to obtain bulk solutions with R x S^3 symmetry in order to explore the AdS/CFT correspondence when the boundary gauge theory is on R x S^3. A fake supergravity action, invariant under local supersymmetry through linear order in fermion fields, is obtained. The gauge field makes things more restrictive than in previous applications of fake supergravity which allowed quite general scalar potentials. Here the superpotential must take the form W(\phi) ~ exp(-k\phi) + c exp(2\phi/(3k)), and the only freedom is the choice of the constant k. The fermion transformation rules of fake supergravity lead to fake Killing spinor equations. From their integrability conditions, we obtain first order differential equations which we solve analytically to find singular electrically charged solutions of the Lagrangian field equations. A Schwarzschild mass term can be added to produce a horizon which shields the singularity. The solutions, which include "superstars", turn out to be known in the literature. We compute their holographic parameters.Comment: 42 pages, 3 figure

Axions In String Theory

In the context of string theory, axions appear to provide the most plausible solution of the strong CP problem. However, as has been known for a long time, in many string-based models, the axion coupling parameter F_a is several orders of magnitude higher than the standard cosmological bounds. We re-examine this problem in a variety of models, showing that F_a is close to the GUT scale or above in many models that have GUT-like phenomenology, as well as some that do not. On the other hand, in some models with Standard Model gauge fields supported on vanishing cycles, it is possible for F_a to be well below the GUT scale.Comment: 62 pages, v2; references, acknowledgements and minor corrections adde