Paraumbilical collateral veins on MRI as possible protection against portal venous thrombosis in candidates for liver transplantation

Background: We retrospectively evaluate the potential protective influence of patent paraumblical vein (PUV) collaterals against portal vein (PV) thrombosis and reduced PV diameter in candidates for orthotopic liver transplant (OLT) Methods: Dynamic 3D contrast-enhanced MRI at 1.5T was obtained in 309 patients with cirrhosis without evidence of malignancy. All MR studies were reviewed by one reader for PUV collaterals, PV thrombosis and PV diameter. Statistical analysis was performed by Fisher exact tests; 50 selected studies were reviewed independently by two additional readers to determine interobserver agreement via intraclass correlation coefficient (ICC). Results: Patent PUV was noted in 119 of 309 patients (38.5%). Mean PV diameter was 13.4 ± 3.0 mm in patients with PUV compared with 11.3 ± 3.6 mm without PUV (P \u3c 0.01). Main PV thrombosis was present in 13 of 309 patients (4.2%) and significantly more frequent in those without PUV than with PUV (6.3% vs. 0.8%, P \u3c 0.05). ICC indicated almost perfect agreement among three readers for presence of PUV collaterals (ICC = 0.91) and PV thrombosis (ICC = 0.96). Conclusion: Our results suggest that patients with patent PUV appear less likely to develop main PV thrombosis or small PV diameter, suggesting a protective effect of PUV on PV patency

Realizability of metamaterials with prescribed electric permittivity and magnetic permeability tensors

We show that any pair of real symmetric tensors \BGve and \BGm can be realized as the effective electric permittivity and effective magnetic permeability of a metamaterial at a given fixed frequency. The construction starts with two extremely low loss metamaterials, with arbitrarily small microstructure, whose existence is ensured by the work of Bouchitt{\'e} and Bourel and Bouchitt\'e and Schweizer, one having at the given frequency a permittivity tensor with exactly one negative eigenvalue, and a positive permeability tensor, and the other having a positive permittivity tensor, and a permeability tensor having exactly one negative eigenvalue. To achieve the desired effective properties these materials are laminated together in a hierarchical multiple rank laminate structure, with widely separated length scales, and varying directions of lamination, but with the largest length scale still much shorter than the wavelengths and attenuation lengths in the macroscopic effective medium.Comment: 12 pages, no figure

Enhanced product realization techniques using as-built and model reconstruction technologies

Los Alamos National Laboratory`s Center for Advanced Engineering Technology has developed a product realization process designed to enhance the complexity and comprehensiveness of the information fed back to the designer after the analytical and manufacturing operations have been completed. This process uses principles of As-Built Engineering and Model Reconstruction in a Models Based Engineering environment, allowing optimization in the manufacturing and assembly operations and providing information as to the As-Built configuration to engineering and physics designers for evaluation. As-Built Engineers is a product realization methodology founded on the notion that life-cycle engineering should be based on what is actually produced and not on what is nominally designed. It enables customization in mass production environments and questions nominal based methods of engineering. Model Reconstruction provides the capability of subjecting a design to adverse conditions within the computer aided environment and building a stereolithography model and simulated radiograph from the analytical finite element information of the simulated damaged part. Models Based Engineering is an information management tool and a key driver toward the development of adaptive product realization infrastructures. It encompasses the breadth of engineering information, from concept through design to product application

Structure and mechanism of acetolactate decarboxylase

Acetolactate decarboxylase catalyzes the conversion of both enantiomers of acetolactate to the (R)-enantiomer of acetoin, via a mechanism that has been shown to involve a prior rearrangement of the non-natural (R)-enantiomer substrate to the natural (S)-enantiomer. In this paper, a series of crystal structures of ALDC complex with designed transition state mimics are reported. These structures, coupled with inhibition studies and site-directed mutagenesis provide an improved understanding of the molecular processes involved in the stereoselective decarboxylation/protonation events. A mechanism for the transformation of each enantiomer of acetolactate is proposed

Willingness to participate in future HIV prevention studies among gay and bisexual men in Scotland, UK: a challenge for intervention trials

This article examines willingness to participate in future HIV prevention research among gay and bisexual men in Scotland, UK. Anonymous, self-complete questionnaires and Orasure Gäó oral fluid samples were collected in commercial gay venues. 1,320 men were eligible for inclusion. 78.2% reported willingness to participate in future HIV prevention research; 64.6% for an HIV vaccine, 57.4% for a behaviour change study, and 53.0% for a rectal microbicide. In multivariate analysis, for HIV vaccine research, greater age, minority ethnicity, and not providing an oral fluid sample were associated with lower willingness; heterosexual orientation and not providing an oral fluid sample were for microbicides; higher education and greater HIV treatment optimism were for behaviour change. STI testing remained associated with being more willing to participate in microbicide research and frequent gay scene use remained associated with being more willing to participate in behaviour change research. Having an STI in the past 12 months remained significantly associated with being willing to participate in all three study types. There were no associations between sexual risk behaviour and willingness. Although most men expressed willingness to participate in future research, recruitment of high-risk men, who have the potential to benefit most, is likely to be more challenging

Faunistic Composition, Ecological Properties and Zoogeographical Composition of the Family Elateridae (Coleoptera) of the Central Anatolian Region of Turkey

The focus of this study was to understand the faunistic composition, ecological properties and zoogeographical composition of Elateridae (Coleoptera) of the Central Anatolian region. 72 species belonging to seven subfamilies and 25 genera were identified. The major part of the Elateridae fauna of the Central Anatolian region is formed by the subfamilies Elaterinae and Cardiophorinae. The genus Cardiophorus was the most species-rich genus. The species composition of the Elateridae fauna of the Central Anatolian region is partially consistent with known Elateridae fauna of Turkey. The Central Anatolian region shares most species with the European part of the Western Palaearctic as does the Elateridae fauna of Turkey. Detailed localities of nine species are given for the first time for Turkey, with emphasis on the Central Anatolian region

Transformation-based spherical cloaks designed by an implicit transformation-independent method: theory and optimization

Based on the concept of the cloak generating function, we propose an implicit transformation-independent method for the required parameters of spherical cloaks without knowing the needed coordinate transformation beforehand. A non-ideal discrete model is used to calculate and optimize the total scattering cross-sections of different profiles of the generating function. A bell-shaped quadratic spherical cloak is found to be the best candidate, which is further optimized by controlling the design parameters involved. Such improved invisibility is steady even when the model is highly discretized.European Commission (European Network of Excellence 'METAMORPHOSE')Foundation for Fundamental Research (Belarus) (F08MS-06

Mathematical analysis of the two dimensional active exterior cloaking in the quasistatic regime

We design a device that generates fields canceling out a known probing field inside a region to be cloaked while generating very small fields far away from the device. The fields we consider satisfy the Laplace equation, but the approach remains valid in the quasistatic regime in a homogeneous medium. We start by relating the problem of designing an exterior cloak in the quasistatic regime to the classic problem of approximating a harmonic function with harmonic polynomials. An explicit polynomial solution to the problem was given earlier in [Phys. Rev. Lett. 103 (2009), 073901]. Here we show convergence of the device field to the field needed to perfectly cloak an object. The convergence region limits the size of the cloaked region, and the size and position of the device.Comment: submitted to Analysis and Mathematical Physic