9,079 research outputs found

    Cholangiographic Features in the Diagnosis and Management of Obstructive Icteric Type Hepatocellular Carcinoma

    Get PDF
    In 11 years and 3 months, 2037 patients with HCC were seen and 48 patients (2.4%) were diagnosed to have obstructive icteric type HCC. Five patients were terminally ill and were not investigated further. Forty three patients were initially investigated by endoscopic retrograde cholangiography (ERC) or percutaneous transhepatic cholangiogram (PTC) and classified as having obstructive icteric type 1, 2, or 3 HCC based on the cholangiographic findings. The obstruction in type 1 HCC was due to intraluminal tumour casts and/or tumour fragments obstructing the hepatic ductal confluence or common bile duct, while intraluminal blood clots, from haemobilia, filling the biliary tree was the cause in type 2 HCC. The pathology in type 3 HCC was extraluminal obstruction by extensive tumour encasement of the intra–hepatic biliary ductal system and/or extrinsic compression of the hepatic and common bile ducts by tumour(s) and/or malignant lymph nodes. At the initial ERC/PTC, 10 patients (5 resected, 50%) had obstructive icteric type 1 and 23 patients (0 resected) had obstructive icteric type 3 HCC. Of the 10 patients initially classified according to cholangiography to have obstructive icteric type 2 HCC, subsequent investigations revealed that 6 patients had type 1 HCC (4 resectable, 67%) and 4 patients had type 3 HCC (0 resectable). The classification of the obstructive icteric type HCC into types 1, 2, and 3, based on the initial cholangiographic appearances has simplified and rationalized our management strategy for this condition

    Steric constraints in model proteins

    Full text link
    A simple lattice model for proteins that allows for distinct sizes of the amino acids is presented. The model is found to lead to a significant number of conformations that are the unique ground state of one or more sequences or encodable. Furthermore, several of the encodable structures are highly designable and are the non-degenerate ground state of several sequences. Even though the native state conformations are typically compact, not all compact conformations are encodable. The incorporation of the hydrophobic and polar nature of amino acids further enhances the attractive features of the model.Comment: RevTex, 5 pages, 3 postscript figure

    Collider Phenomenology with Split-UED

    Get PDF
    We investigate the collider implications of Split Universal Extra Dimensions. The non-vanishing fermion mass in the bulk, which is consistent with the KK-parity, largely modifies the phenomenology of Minimal Universal Exta Dimensions. We scrutinize the behavior of couplings and study the discovery reach of the Tevatron and the LHC for level-2 Kaluza-Klein modes in the dilepton channel, which would indicates the presence of the extra dimensions. Observation of large event rates for dilepton resonances can result from a nontrivial fermion mass profile along the extra dimensions, which, in turn, may corroborate extra dimensional explanation for the observation of the positron excess in cosmic rays.Comment: 23 pages, 15 figure

    Detecting the direction of a signal on high-dimensional spheres: Non-null and Le Cam optimality results

    Full text link
    We consider one of the most important problems in directional statistics, namely the problem of testing the null hypothesis that the spike direction θ\theta of a Fisher-von Mises-Langevin distribution on the pp-dimensional unit hypersphere is equal to a given direction θ0\theta_0. After a reduction through invariance arguments, we derive local asymptotic normality (LAN) results in a general high-dimensional framework where the dimension pnp_n goes to infinity at an arbitrary rate with the sample size nn, and where the concentration κn\kappa_n behaves in a completely free way with nn, which offers a spectrum of problems ranging from arbitrarily easy to arbitrarily challenging ones. We identify various asymptotic regimes, depending on the convergence/divergence properties of (κn)(\kappa_n), that yield different contiguity rates and different limiting experiments. In each regime, we derive Le Cam optimal tests under specified κn\kappa_n and we compute, from the Le Cam third lemma, asymptotic powers of the classical Watson test under contiguous alternatives. We further establish LAN results with respect to both spike direction and concentration, which allows us to discuss optimality also under unspecified κn\kappa_n. To investigate the non-null behavior of the Watson test outside the parametric framework above, we derive its local asymptotic powers through martingale CLTs in the broader, semiparametric, model of rotationally symmetric distributions. A Monte Carlo study shows that the finite-sample behaviors of the various tests remarkably agree with our asymptotic results.Comment: 47 pages, 4 figure

    Exploring the ageing methylome in the model insect, Nasonia vitripennis

    Get PDF
    Background: The ageing process is a multifaceted phenomenon marked by the gradual deterioration of cellular and organismal functions, accompanied by an elevated susceptibility to diseases. The intricate interplay between genetic and environmental factors complicates research, particularly in complex mammalian models. In this context, simple invertebrate organisms have been pivotal, but the current models lack detectable DNA methylation limiting the exploration of this critical epigenetic ageing mechanism. This study introduces Nasonia vitripennis, the jewel wasp, as an innovative invertebrate model for investigating the epigenetics of ageing. Leveraging its advantages as a model organism and possessing a functional DNA methylation system, Nasonia emerges as a valuable addition to ageing research. Results: Whole-genome bisulfite sequencing unveiled dynamic alterations in DNA methylation, with differentially methylated CpGs between distinct time points in both male and female wasps. These changes were associated with numerous genes, enriching for functions related to telomere maintenance, histone methylation, and mRNA catabolic processes. Additionally, other CpGs were found to be variably methylated at each timepoint. Sex-specific effects on epigenetic entropy were observed, indicating differential patterns in the loss of epigenetic stability over time. Constructing an epigenetic clock containing 19 CpGs revealed a robust correlation between epigenetic age and chronological age. Conclusions: Nasonia vitripennis emerges as a promising model for investigating the epigenetics of ageing, shedding light on the intricate dynamics of DNA methylation and their implications for age-related processes. This research not only expands the repertoire of ageing models but also opens avenues for deeper exploration of epigenetic mechanisms in the context of ageing

    Sonic boom and drag evaluation of supersonic jet concepts

    Get PDF
    This paper evaluates three different class supersonic airliners (Concorde, Cranfield E-5, and NASA QueSST X-plane) in a multidisciplinary design analysis optimization (MDAO) environment in terms of their sonic boom intensities and aerodynamic performance. The aerodynamic analysis and sonic boom prediction methods are key to this research. The panel method PANAIR is integrated to perform automated aerodynamic analysis. The drag coefficient is corrected by the Harris wave drag formula and form factor method. For sonic boom prediction, the near-field pressure is predicted through the Whitham F-function method. The F-function is decomposed to the F-function due to volume and the F-function due to lift to see their individual effect on sonic boom. The near-field signature propagates in a stratified windy atmosphere using the waveform parameter method. The aerodynamic results are compared with experimental data and the sonic boom prediction results are validated by the NASA PCBoom program. Through the evaluation, we find a direct link between the wave drag and the first derivative of the volume distribution. The sonic boom intensity is influenced by the lift distribution and the volume change rate. The study helps to study the feasibility of low-boom and low-drag supersonic airliners

    Covalent Organic Framework (COF) derived Ni-N-C Catalysts for Electrochemical CO<sub>2</sub> Reduction: Unraveling Fundamental Kinetic and Structural Parameters of the Active Sites

    Get PDF
    Electrochemical CO2 reduction is a potential approach to convert CO2 into valuable chemicals using electricity as feedstock. Abundant and affordable catalyst materials are needed to upscale this process in a sustainable manner. Nickel-nitrogen-doped carbon (Ni-N-C) is an efficient catalyst for CO2 electro-reduction to CO, and the single-site Ni-Nx motif is believed as the active site. However, critical metrics for its catalytic activity, such as active site density and intrinsic turnover frequency, so far lack systematic discussion. In this work, we prepared a set of covalent organic framework (COF)-derived Ni-N-C catalysts, for which the Ni-Nx content could be adjusted by the pyrolysis temperature. The combination of high-angle annular dark-field scanning transmission electron microscopy and extended X-ray absorption fine structure evidenced the presence of Ni single-sites, and quantitative X-ray photoemission addressed the relation between active site density and turnover frequency
    corecore