145 research outputs found

    Geometric, electronic properties and the thermodynamics of pure and Al--doped Li clusters

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    The first--principles density functional molecular dynamics simulations have been carried out to investigate the geometric, the electronic, and the finite temperature properties of pure Li clusters (Li10_{10}, Li12_{12}) and Al--doped Li clusters (Li10_{10}Al, Li10_{10}Al2_2). We find that addition of two Al impurities in Li10_{10} results in a substantial structural change, while the addition of one Al impurity causes a rearrangement of atoms. Introduction of Al--impurities in Li10_{10} establishes a polar bond between Li and nearby Al atom(s), leading to a multicentered bonding, which weakens the Li--Li metallic bonds in the system. These weakened Li--Li bonds lead to a premelting feature to occur at lower temperatures in Al--doped clusters. In Li10_{10}Al2_2, Al atoms also form a weak covalent bond, resulting into their dimer like behavior. This causes Al atoms not to `melt' till 800 K, in contrast to the Li atoms which show a complete diffusive behavior above 400 K. Thus, although one Al impurity in Li10_{10} cluster does not change its melting characteristics significantly, two impurities results in `surface melting' of Li atoms whose motions are confined around Al dimer.Comment: 9 pages, 7 figure

    Laparoscopic resection of a appendiceal mucocele

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    Laparoscopic resection of appendiceal mucoceles has recently been described, but the safety and efficacy are controversial. We present two cases of laparoscopic mucocelectomies involving 14 and 15 cm cystic masses originating from the appendix. The laparoscopic mucocelectomies were performed using four ports. From the beginning of the procedure, a laparoscopic bag was used to safely contain the mucocele, prevent rupture of the mucocele, and retract the mucocele. An endoscopic stapling device was used to transect the base of the cecum. Minimal handling was achieved by gravity and with the use of laparoscopic instruments. Laparoscopic appendectomies are widely performed for acute appendicitis, but laparoscopic resection is not routinely performed for an appendiceal mucocele because of the risk of perforation and subsequent pseudomyxoma peritonei. We report two cases of laparoscopic appendiceal mucocelectomies, which were performed safely with laparoscopic instruments and minimal manipulation

    Hepatitis B Virus Genotype C Prevails Among Chronic Carriers of the Virus in Korea

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    Hepatitis B virus (HBV) is one of the major causative agents of chronic liver diseases in Korea. HBV has been classified into 8 genotypes by a divergence of >8% in the entire genomic sequence, and have distinct geographic distributions. There are limited data on the relevance between HBV genotypes and clinical outcomes in Korea. To investigate the clinical feature relating to HBV genotype in Korea, a total 120 serum samples with HBsAg (65 from Seoul and 55 from the other city in Korea) were obtained from each 30 chronic HBV carriers with asymptomatic carrier (ASC), chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). HBV genotype was determined by either enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies against genotype-specific epitopes in the preS2-region or the direct sequencing of small S gene. HBV genotypes were determined in 105 (87.5%) of 120 samples. HBV genotype C was identified in all HBV carriers with ASC, CH, LC, and HCC. Genotypes A, B, D, E, F and G were not detected in any of them. Genotype C HBV prevails predominantly among chronic carriers of the virus in Korea, irrespective of their clinical stages of liver disease and geographic origin

    Fungal communities are differentially affected by conventional and biodynamic agricultural management approaches in vineyard ecosystems

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    There is increased need to identify sustainable agricultural methods which avoid environmental degradation. Previous studies have focused on the effect of specific agricultural interventions on large organisms, but we have fewer data evaluating how microbes, which are key components of ecosystems, might be affected. Additionally, previous studies have been constrained as they only examined one habitat in an ecosystem and have not gone on to evaluate the effect of agricultural approach on harvested crops. Here we take an ecosystems approach and evaluate the net effect of conventional versus biodynamic management on agricultural ecosystems by quantifying fungal communities in multiple habitats using metagenomics. We go on to measure biodiversity in the crop and key chemical quality parameters in the product consumed by humans. We find that the method of management significantly affects communities in soil, on plant structures, and on the developing crop in subtle but importantly different ways in terms of number, type, and abundance of species. However, management approach has no effect on communities in the final harvested juice, nor on product traits aligned with quality. This shows that while management approach impacts different habitats in the environment in different ways, this does not automatically flow onto the harvested crop

    Free will debates: Simple experiments are not so simple

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    The notion that free will is an illusion has achieved such wide acceptance among philosophers and neuroscientists that it seems to be acquiring the status of dogma. Nonetheless, research in this area continues, and this review offers a new analysis of the design limitations and data interpretations of free-will experiments. This review presents 12 categories of questionable conclusions that some scholars use to promote the idea that free will is an illusion. The next generation of less ambiguous experiments is proposed

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
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