Liver transplantation

Purpose of review: Long-term survival of liver transplant recipients is threatened by increased rates of de-novo malignancy and recurrence of hepatocellular carcinoma (HCC), both events tightly related to immunosuppression. Recent findings: There is accumulating evidence linking increased exposure to immunosuppressants and carcinogenesis, particularly concerning calcineurin inhibitors (CNIs), azathioprine and antilymphocyte agents. A recent study including 219 HCC transplanted patients showed that HCC recurrence rates were halved if a minimization of CNIs was applied within the first month after liver transplant. With mammalian target of rapamycin (mTOR) inhibitors as approved immunosuppressants for liver transplant patients, pooled data from several retrospective studies have suggested their possible benefit for reducing HCC recurrence. Summary: Randomized controlled trials with sufficiently long follow-up are needed to evaluate the influence of different immunosuppression protocols in preventing malignancy after LT. Currently, early minimization of CNIs with or without mTOR inhibitors or mycophenolate seems a rational strategy for patients with risk factors for de-novo malignancy or recurrence of HCC after liver transplant. A deeper understanding of the immunological pathways of rejection and cancer would allow for designing more specific and safer drugs, and thus to prevent cancer after liver transplant

Fear expression and return of fear following threat instruction with or without direct contingency experience

Prior research showed that mere instructions about the contingency between a conditioned stimulus (CS) and an unconditioned stimulus (US) can generate fear reactions to the CS. Little is known, however, about the extent to which actual CS US contingency experience adds anything beyond the effect of contingency instructions. Our results extend previous studies on this topic in that it included fear potentiated startle as an additional dependent variable and examined return of fear (ROF) following reinstatement. We observed that CS US pairings can enhance fear reactions beyond the effect of contingency instructions. Moreover, for all measures of fear, instructions elicited immediate fear reactions that could not be completely overridden by subsequent situational safety information. Finally, ROF following reinstatement for instructed CS+s was unaffected by actual experience. In summary, our results demonstrate the power of contingency instructions and reveal the additional impact of actual experience of CS US pairings

A vine copula mixed effect model for trivariate meta-analysis of diagnostic test accuracy studies accounting for disease prevalence

A bivariate copula mixed model has been recently proposed to synthesize diagnostic test accuracy studies and it has been shown that it is superior to the standard generalized linear mixed model in this context. Here, we call trivariate vine copulas to extend the bivariate meta-analysis of diagnostic test accuracy studies by accounting for disease prevalence. Our vine copula mixed model includes the trivariate generalized linear mixed model as a special case and can also operate on the original scale of sensitivity, specificity, and disease prevalence. Our general methodology is illustrated by re-analyzing the data of two published meta-analyses. Our study suggests that there can be an improvement on trivariate generalized linear mixed model in fit to data and makes the argument for moving to vine copula random effects models especially because of their richness, including reflection asymmetric tail dependence, and computational feasibility despite their three dimensionality

Mechanistic insights into the Cu(I) oxide-catalyzed conversion of CO2 to fuels and chemicals: A DFT approach

Periodic, self-consistent, density functional theory calculations with corrections via a Hubbard U parameter, and inclusion of dispersive forces (DFT-D2), have been employed to study CO2 activation and conversion on the Cu2O (1 1 1) surface. CO2 hydrogenation on the Cu2O (1 1 1) surface was investigated systematically, and the respective microscopic reaction mechanisms were elucidated. We show that, whereas CO2 dissociation is not energetically allowed on the Cu2O (1 1 1) surface, CO2 hydrogenation to a formate intermediate is more favourable than the formation of a carboxyl intermediate. Further hydrogenation from formate to formic acid is energetically allowed, where formate combines with strongly adsorbed surface hydrogen to form bidentate formic acid moieties. Formation of both the formate and the formic acid from adsorbed CO2 and surface hydrogen are exothermic reactions

Evaluation of On- farm produced Novcom Compost Quality and its Post Soil Application Effectivity in Acid Tea Soils – A Case Study from West Jalinga Tea Estate, the Largest Organic Tea Estate in Assam, India.

A new composting process known as Novcom composting method is being used for on-farm production of compost at West Jalinga Tea Estate (presently largest certified organic tea estate in Assam, India). The method has been developed by Dr. P. Das Biswas, an Indian Scientist who has been associated with organic research for the last decade. Novcom compost produced under this method is being used for soil management in the garden. The composting process enables production of mature compost within a period of 21 days. Quality of Novcom compost and its post soil application effectivity in terms of soil development were studied during the period 2006-7 to 2012-13. The samples were analyzed for physicochemical properties, nutrient content, ready nutrient supplying potential, microbial status, stability, maturity and phytotoxicity status; and the values obtained for the different parameters were within the standard suggested reference range. Soil microbial population increased by 1,000 to 10,000 times, apart from significant increase recorded in case of soil organic carbon (49.4%) and soil fertility (Available-N: 13.6%, P2O5: 5.8% and K2O: 9.5%). Post soil application effectivity of Novcom compost was documented both in terms of significant soil quality development as well as yield sustenance at West Jalinga T.E. which had been applying the compost @ 3 ton/ha/year; over a period of seven years. The study revealed that Novcom composting method could serve as an alternate option for production of good quality on-farm compost in order to enable effective soil management

CuO Surfaces and CO2 Activation: A Dispersion-Corrected DFT+U Study

We have used computational methodology based on the density functional theory to describe both copper(I) and copper(II) oxides, followed by the investigation of a number of different low index CuO surfaces. Different magnetic orderings of all the surfaces were studied and reconstructions of the polar surfaces are proposed. A detailed discussion on stabilities, electronic structure and magnetic properties is presented. CuO(111) and CuO(-111) were found to have the lowest surface energies and their planes dominate in the calculated Wulff morphology of the CuO crystal. We next investigated the adsorption of CO2 on the three most exposed CuO surfaces, viz. (111), (-111) and (011) by exploring various adsorption sites and configurations. We show that the CO2 molecule is activated on the CuO surfaces, with an adsorption energy of -93 kJ/mol on the (011) surface, showing exothermic adsorption, while (111) and (-111) surfaces show comparatively weak adsorption. The activation of the CO2 molecule is characterized by large structural transformations and significant charge transfer, i.e., forming a negatively charged bent CO2 -δ species with elongated C-O bonds, which is further confirmed by vibrational analyses showing considerable red shift in the frequencies as a result of the activation

C IV BAL disappearance in a large SDSS QSO sample

Broad absorption lines (BALs) in the spectra of quasi-stellar objects (QSOs) originate from outflowing winds along our line of sight; winds are thought to originate from the inner regions of the QSO accretion disk, close to the central supermassive black hole (SMBH). Winds likely play a role in galaxy evolution and aid the accretion mechanism onto the SMBH. BAL equivalent widths can change on typical timescales from months to years; such variability is generally attributed to changes in the covering factor and/or in the ionization level of the gas. We investigate BAL variability, focusing on BAL disappearance. We analyze multi-epoch spectra of more than 1500 QSOs -the largest sample ever used for such a study- observed by different programs from the Sloan Digital Sky Survey-I/II/III (SDSS), and search for disappearing C IV BALs. The spectra rest-frame time baseline ranges from 0.28 to 4.9 yr; the source redshifts range from 1.68 to 4.27. We detect 73 disappearing BALs in the spectra of 67 sources. This corresponds to 3.9% of disappearing BALs, and 5.1% of our BAL QSOs exhibit at least one disappearing BAL. We estimate the average lifetime of a BAL along our line of sight (~ 80-100 yr), which appears consistent with the accretion disk orbital time at distances where winds are thought to originate. We inspect properties of the disappearing BALs and compare them to the properties of our main sample. We also investigate the existence of a correlation in the variability of multiple troughs in the same spectrum, and find it persistent at large velocity offsets between BAL pairs, suggesting that a mechanism extending on a global scale is necessary to explain the phenomenon. We select a more reliable sample of disappearing BALs following Filiz Ak et al. (2012), where a subset of our sample was analyzed, and compare the findings from the two works, obtaining generally consistent results.Comment: 22 pages, 9 figures. Accepted for publication in A&

Nonparametric Regression via StatLSSVM

We present a new MATLAB toolbox under Windows and Linux for nonparametric regression estimation based on the statistical library for least squares support vector machines (StatLSSVM). The StatLSSVM toolbox is written so that only a few lines of code are necessary in order to perform standard nonparametric regression, regression with correlated errors and robust regression. In addition, construction of additive models and pointwise or uniform confidence intervals are also supported. A number of tuning criteria such as classical cross-validation, robust cross-validation and cross-validation for correlated errors are available. Also, minimization of the previous criteria is available without any user interaction

Les poisons de flèches utilisés par les Pygmées de la préfecture de la Lobaye (République Centrafricaine)

Les détenteurs des savoirs traditionnels sont généralement des personnes âgées. Souvent, celles-ci meurent sans transmettre leurs connaissances aux jeunes de plus en plus désintéressés. Ainsi, avant que cela ne soit trop tard, nous nous sommes fixés pour objectif de rassembler les  informations sur les poisons de flèches utilisés par les Pygmées de la préfecture de la Lobaye. Pour cela, nous avons conduit des enquêtesethnobotaniques. Quinze personnes ont été interrogées, quatorze  Pygmées Aka et un « villageois ». Au total, nous avons recensé 25 espèces de plantes pour lesquelles 21 sont indiquées comme entrant dans la préparation des poisons de flèches dans cette région ; les quatre autres espèces sont utilisées pour la fabrication d’arcs, d’arbalètes et de sagaies. Treize des 25 espèces sont signalées dans la littérature comme étant utilisées comme poisons de flèches. Periploca nigrescens Afzel.  (Apocynaceae) constitue l’élément principal de plusieurs poisons.Mots clés : Poisons de flèches, Pygmées, enquêtes ethnobotaniques, République Centrafricaine