Novel Synthesis and High Pressure Behavior of Na0.3CoO2 x 1.3 H2O and Related Phases

We have prepared powder samples of NaxCoO2 x yH2O using a new synthesis route. Superconductivity was observed in Na0.3CoO2 x 1.3H2O between 4 and 5K as indicated by the magnetic susceptibility. The bulk compressibilities of Na0.3CoO2 x 1.3H2O, Na0.3CoO2 x 0.6H2O and Na0.3CoO2 were determined using a diamond anvil cell and synchrotron powder diffraction. Chemical changes occurring under pressure when using different pressure transmitting media are discussed and further transport measurements are advocated.Comment: 7 pages, 4 figures, PRrapid submitte

Quantitative Comparison of Sinc-Approximating Kernels for Medical Image Interpolation

Abstract. Interpolation is required in many medical image processing operations. From sampling theory, it follows that the ideal interpolation kernel is the sinc function, which is of infinite extent. In the attempt to obtain practical and computationally efficient image processing al-gorithms, many sinc-approximating interpolation kernels have been de-vised. In this paper we present the results of a quantitative comparison of 84 different sinc-approximating kernels, with spatial extents ranging from 2 to 10 grid points in each dimension. The evaluation involves the application of geometrical transformations to medical images from dif-ferent modalities (CT, MR, and PET), using the different kernels. The results show very clearly that, of all kernels with a spatial extent of 2 grid points, the linear interpolation kernel performs best. Of all kernels with an extent of 4 grid points, the cubic convolution kernel is the best (28 %- 75 % reduction of the errors as compared to linear interpolation). Even better results (44 %- 95 % reduction) are obtained with kernels of larger extent, notably the Welch, Cosine, Lanczos, and Kaiser windowed sinc kernels. In general, the truncated sinc kernel is one of the worst performing kernels.

High-speed polarization sensitive optical frequency domain imaging with frequency multiplexing

Polarization sensitive optical coherence tomography (PS-OCT) provides a cross-sectional image of birefringence in biological samples that is complementary in many applications to the standard reflectance-based image. Recent ex vivo studies have demonstrated that birefringence mapping enables the characterization of collagen and smooth muscle concentration and distribution in vascular tissues. Instruments capable of applying these measurements percutaneously in vivo may provide new insights into coronary atherosclerosis and acute myocardial infarction. We have developed a polarization sensitive optical frequency domain imaging (PS-OFDI) system that enables high-speed intravascular birefringence imaging through a fiber-optic catheter. The novel design of this system utilizes frequency multiplexing to simultaneously measure reflectance of two incident polarization states, overcoming concerns regarding temporal variations of the catheter fiber birefringence and spatial variations in the birefringence of the sample. We demonstrate circular cross-sectional birefringence imaging of a human coronary artery ex vivo through a flexible fiber-optic catheter with an A-line rate of 62 kHz and a ranging depth of 6.2 mm

Invasive species

Globally, about 2,000 marine non-indige¬nous species (NIS) have been introduced to new locations through human-mediated movements. A few of those have econom¬ic value, but most have had negative eco¬logical, socioeconomic or human health impacts. With increased trade and climate change, biological invasions are likely to increase

The dynamic adaptive landscape of cetacean body size

Adaptive landscapes are central to evolutionary theory, forming a conceptual bridge between micro- and macroevolution.1,2,3,4 Evolution by natural selection across an adaptive landscape should drive lineages toward fitness peaks, shaping the distribution of phenotypic variation within and among clades over evolutionary timescales.5 The location and breadth of these peaks in phenotypic space can also evolve,4 but whether phylogenetic comparative methods can detect such patterns has largely remained unexplored.6 Here, we characterize the global and local adaptive landscape for total body length in cetaceans (whales, dolphins, and relatives), a trait that spans an order of magnitude, across their ∼53-million-year evolutionary history. Using phylogenetic comparative methods, we analyze shifts in long-term mean body length7 and directional changes in average trait values8 for 345 living and fossil cetacean taxa. Remarkably, we find that the global macroevolutionary adaptive landscape of cetacean body length is relatively flat, with very few peak shifts occurring after cetaceans entered the oceans. Local peaks are more numerous and manifest as trends along branches linked to specific adaptations. These results contrast with previous studies using only extant taxa,9 highlighting the vital role of fossil data for understanding macroevolution.10,11,12 Our results indicate that adaptive peaks are dynamic and are associated with subzones of local adaptations, creating moving targets for species adaptation. In addition, we identify limits in our ability to detect some evolutionary patterns and processes and suggest that multiple approaches are required to characterize complex hierarchical patterns of adaptation in deep time

Density mismatch in thin diblock copolymer films

Thin films of diblock copolymer subject to gravitational field are simulated by means of a cell dynamical system model. The difference in density of the two sides of the molecule and the presence of the field causes the formation of lamellar patterns with orientation parallel to the confining walls even when they are neutral. The concentration profile of those films is analyzed in the weak segregation regime and a functional form for the profile is proposed.Comment: 9 pages and 8 figures. Needs EPSF macros. Submitted to PR

Developing a career as a GP educationalist: contemporary challenges and workforce solutions

GP educationalists are crucial in training the future medical workforce and in developing and advancing the field of primary care medical education, yet opportunities in the UK are patchy and varied. In this article, a group of GP educationalists summarise the challenges facing the sustainability of this particular group of clinical academics and outline opportunities available at each career stage, from medical students through to senior GP educationalists. Recommendations to support the growth of this workforce include the development of a nationally recognised framework for GP educationalist careers, collaboration with professional and educational bodies and taking steps to level out opportunities in order to reduce existing inequity

Flavor changing Z-decays from scalar interactions at a Giga-Z Linear Collider

The flavor changing decay Z -> d_I \bar{d}_J is investigated with special emphasis on the b \bar{s} final state. Various models for flavor violation are considered: two Higgs doublet models (2HDM's), supersymmetry (SUSY) with flavor violation in the up and down-type squark mass matrices and SUSY with flavor violation mediated by R-parity-violating interaction. We find that, within the SUSY scenarios for flavor violation, the branching ratio for the decay Z -> b \bar{s} can reach 10^{-6} for large \tan\beta values, while the typical size for this branching ratio in the 2HDM's considered is about two orders of magnitudes smaller at best. Thus, flavor changing SUSY signatures in radiative Z decays such as Z -> b \bar{s} may be accessible to future ``Z factories'' such as a Giga-Z version of the TESLA design.Comment: 27 pages, 15 figures, REVTeX4. A new section added and a few minor corrections were made in the tex