Quasi Two-dimensional Transfer of Elastic Waves

A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.

Identification of commonly expressed exoproteins and proteolytic cleavage events by proteomic mining of clinically relevant UK isolates of Staphylococcus aureus

The range of exoproteins and core exoproteome of 14 Staphylococcus aureus isolates representing major lineages associated with asymptomatic carriage and clinical disease in the UK was identified by MS proteomics using a combined database incorporating sequences derived from 39 S. aureus genomes. In all, 632 different proteins were identified and, of these, only 52 (8 %) were found in all 14 isolates whereas 144 (23 %) were found in just a single isolate. Comparison of the observed mass of each protein (based on migration by SDS-PAGE) with its predicted mass (based on amino acid sequence) suggested that 95 % of the proteins identified were not subject to any major post-translational modification. Migration of 5 % of the proteins was not as expected: 1 % of the proteins migrated at a mass greater than predicted, while 4 % appeared to have undergone proteolytic cleavage; these included SsaA2, Aur, SspP, Ebh as well as BlaR1, MecR1, FsH, OatA and LtaS. Intriguingly, a truncated SasG was produced by a single CC8 USA300-like strain. The analysis provided evidence of the marked heterogeneity in protein expression by S. aureus in broth, while yielding a core but narrow common exoproteome

CBR Anisotropy from Primordial Gravitational Waves in Two-Component Inflationary Cosmology

We examine stochastic temperature fluctuations of the cosmic background radiation (CBR) arising via the Sachs-Wolfe effect from gravitational wave perturbations produced in the early universe. We consider spatially flat, perturbed FRW models that begin with an inflationary phase, followed by a mixed phase containing both radiation and dust. The scale factor during the mixed phase takes the form $a(\eta)=c_1\eta^2+c_2\eta+c_3$, where $c_i$ are constants. During the mixed phase the universe smoothly transforms from being radiation to dust dominated. We find analytic expressions for the graviton mode function during the mixed phase in terms of spheroidal wave functions. This mode function is used to find an analytic expression for the multipole moments $\langle a_l^2\rangle$ of the two-point angular correlation function $C(\gamma)$ for the CBR anisotropy. The analytic expression for the multipole moments is written in terms of two integrals, which are evaluated numerically. The results are compared to multipoles calculated for models that are {\it completely} dust dominated at last-scattering. We find that the multipoles $\langle a_l^2\rangle$ of the CBR temperature perturbations for $l>10$ are significantly larger for a universe that contains both radiation and dust at last-scattering. We compare our results with recent, similar numerical work and find good agreement. The spheroidal wave functions may have applications to other problems of cosmological interest.Comment: 28 pgs + 6 postscript figures, RevTe

Improving adherence to acute low back pain guideline recommendations with chiropractors and physiotherapists: the ALIGN cluster randomised controlled trial

Background Acute low back pain is a common condition, has high burden, and there are evidence-to-practice gaps in the chiropractic and physiotherapy setting for imaging and giving advice to stay active. The aim of this cluster randomised trial was to estimate the effects of a theory- and evidence-based implementation intervention to increase chiropractors’ and physiotherapists’ adherence to a guideline for acute low back pain compared with the comparator (passive dissemination of the guideline). In particular, the primary aim of the intervention was to reduce inappropriate imaging referral and improve patient low back pain outcomes, and to determine whether this intervention was cost-effective. Methods Physiotherapy and chiropractic practices in the state of Victoria, Australia, comprising at least one practising clinician who provided care to patients with acute low back pain, were invited to participate. Patients attending these practices were included if they had acute non-specific low back pain (duration less than 3 months), were 18 years of age or older, and were able to understand and read English. Practices were randomly assigned either to a tailored, multi-faceted intervention based on the guideline (interactive educational symposium plus academic detailing) or passive dissemination of the guideline (comparator). A statistician independent of the study team undertook stratified randomisation using computer-generated random numbers; four strata were defined by professional group and the rural or metropolitan location of the practice. Investigators not involved in intervention delivery were blinded to allocation. Primary outcomes were X-ray referral self-reported by clinicians using a checklist and patient low back pain-specific disability (at 3 months). Results A total of 104 practices (43 chiropractors, 85 physiotherapists; 755 patients) were assigned to the intervention and 106 practices (45 chiropractors, 97 physiotherapists; 603 patients) to the comparator; 449 patients were available for the patient-level primary outcome. There was no important difference in the odds of patients being referred for X-ray (adjusted (Adj) OR: 1.40; 95% CI 0.51, 3.87; Adj risk difference (RD): 0.01; 95% CI − 0.02, 0.04) or patient low back pain-specific disability (Adj mean difference: 0.37; 95% CI − 0.48, 1.21, scale 0–24). The intervention did lead to improvement for some key secondary outcomes, including giving advice to stay active (Adj OR: 1.96; 95% CI 1.20, 3.22; Adj RD: 0.10; 95% CI 0.01, 0.19) and intending to adhere to the guideline recommendations (e.g. intention to refer for X-ray: Adj OR: 0.27; 95% CI 0.17, 0.44; intention to give advice to stay active: Adj OR: 2.37; 95% CI 1.51, 3.74). Conclusions Intervention group clinicians were more likely to give advice to stay active and to intend to adhere to the guideline recommendations about X-ray referral. The intervention did not change the primary study outcomes, with no important differences in X-ray referral and patient disability between groups, implying that hypothesised reductions in health service utilisation and/or productivity gains are unlikely to offset the direct costs of the intervention. We report these results with the caveat that we enrolled less patients into the trial than our determined sample size. We cannot recommend this intervention as a cost-effective use of resources

Microwave conductivity of a d-wave superconductor disordered by extended impurities: a real-space renormalization group approach

Using a real-space renormalization group (RSRG) technique, we compute the microwave conductivity of a d-wave superconductor disordered by extended impurities. To do this, we invoke a semiclassical approximation which naturally accesses the Andreev bound states localized near each impurity. Tunneling corrections (which are captured using the RSRG) lead to a delocalization of these quasiparticles and an associated contribution to the microwave conductivity.Comment: 8 pages, 4 figures. 2 figures added to previous versio

Renal pericytes: regulators of medullary blood flow

Regulation of medullary blood flow (MBF) is essential in maintaining normal kidney function. Blood flow to the medulla is supplied by the descending vasa recta (DVR), which arise from the efferent arterioles of juxtamedullary glomeruli. DVR are composed of a continuous endothelium, intercalated with smooth muscle-like cells called pericytes. Pericytes have been shown to alter the diameter of isolated and in situ DVR in response to vasoactive stimuli that are transmitted via a network of autocrine and paracrine signalling pathways. Vasoactive stimuli can be released by neighbouring tubular epithelial, endothelial, red blood cells and neuronal cells in response to changes in NaCl transport and oxygen tension. The experimentally described sensitivity of pericytes to these stimuli strongly suggests their leading role in the phenomenon of MBF autoregulation. Because the debate on autoregulation of MBF fervently continues, we discuss the evidence favouring a physiological role for pericytes in the regulation of MBF and describe their potential role in tubulo-vascular cross-talk in this region of the kidney. Our review also considers current methods used to explore pericyte activity and function in the renal medulla

Cosmokinetics: A joint analysis of Standard Candles, Rulers and Cosmic Clocks

We study the accelerated expansion of the universe by using the kinematic approach. In this context, we parameterize the deceleration parameter, q(z), in a model independent way. Assuming three simple parameterizations we reconstruct q(z). We do the joint analysis with combination of latest cosmological data consisting of standard candles (Supernovae Union2 sample), standard ruler (CMB/BAO), cosmic clocks (age of passively evolving galaxies) and Hubble (H(z)) data. Our results support the accelerated expansion of the universe.Comment: PDFLatex, 15 pages, 12 pdf figures, revised version to appear in JCA

Development and validation of an automatic thermal imaging process forassessing plant water status

[EN] Leaf temperature is a physiological trait that can be used for monitoring plant water status. Nowadays, by means of thermography, canopy temperature can be remotely determined. In this sense, it is crucial to automatically process the images. In the present work, a methodology for the automatic analysis of frontal images taken on individual trees was developed. The procedure can be used when cameras take at the same time thermal and visible scenes, so it is not necessary to reference the images. In this way, during the processing in batch, no operator participated. The procedure was developed by means of a non supervised classification of the visible image from which the presence of sky and soil could be detected. In case of existence, a mask was performed for the extraction of intermediate pixels to calculate canopy temperature by means of the thermal image. At the same time, sunlit and shady leaves could be detected and isolated. Thus, the procedure allowed to separately determine canopy temperature either of the more exposed part of the canopy or of the shaded portion. The methodology developed was validated using images taken in several regulated deficit irrigation trials in Persimmon and two citrus cultivars (Clementina de Nules and Navel Lane-Late). Overall, results indicated that similar canopy temperatures were calculated either by means of the automatic process or the manual procedure. The procedure developed allows to drastically reduce the time needed for image analysis also considering that no operator participation was required. This tool will facilitate further investigations in course for assessing the feasibility of thermography for detecting plant water status in woody perennial crops with discontinuous canopies. Preliminary results reported indicate that the type of crop evaluated has an important influence in the results obtained from thermographic imagery. Thus, in Persimmon trees there were good correlations between canopy temperature and plant water status while, in Clementina de Nules and Navel Lane-Late citrus cultivars canopy temperature differences among trees could not be related with tree-to-tree variations in plant water status.This research was supported by funds from the Instituto Valenciano de Investigaciones Agrarias and the "Denominacion de origen Caqui Ribera del Xuquer" via "Proyecto Integral Caqui". from projects Rideco-Consolider CSD2006-0067 and Interreg IV Sudoe Telerieg. Thanks are also due to J. Castel, E. Badal, I. Buesa and D. Guerra for assistance with field work and to the Servicio de Tecnologia del Riego for providing the meteorological data.Jiménez Bello, MÁ.; Ballester, C.; Castel Sanchez, R.; Intrigliolo Molina, DS. (2011). Development and validation of an automatic thermal imaging process forassessing plant water status. Agricultural Water Management. (98):1497-1504. https://doi.org/10.1016/j.agwat.2011.05.002S149715049

Limits on the gravity wave contribution to microwave anisotropies

We present limits on the fraction of large angle microwave anisotropies which could come from tensor perturbations. We use the COBE results as well as smaller scale CMB observations, measurements of galaxy correlations, abundances of galaxy clusters, and Lyman alpha absorption cloud statistics. Our aim is to provide conservative limits on the tensor-to-scalar ratio for standard inflationary models. For power-law inflation, for example, we find T/S<0.52 at 95% confidence, with a similar constraint for phi^p potentials. However, for models with tensor amplitude unrelated to the scalar spectral index it is still currently possible to have T/S>1.Comment: 23 pages, 7 figures, accepted for publication in Phys. Rev. D. Calculations extended to blue spectral index, Fig. 6 added, discussion of results expande