10,369 research outputs found

    Mechanisms of Bacterial Extracellular Electron Exchange.

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    The biochemical mechanisms by which microbes interact with extracellular soluble metal ions and insoluble redox-active minerals have been the focus of intense research over the last three decades. The process presents two challenges to the microorganism; firstly electrons have to be transported at the cell surface, which in Gram negative bacteria presents an additional problem of electron transfer across the ~ 6 nm of the outer membrane. Secondly the electrons must be transferred to or from the terminal electron acceptors or donors. This review covers the known mechanisms that bacteria use to transport electrons across the cell envelope to external electron donors/acceptors. In Gram negative bacteria electron transfer across the outer membrane involves the use of an outer membrane β-barrel and cytochrome. These can be in the form of a porin-cytochrome protein, such as Cyc2 of Acidothiobacillus ferrioxydans, or a multiprotein porin-cytochrome complex like MtrCAB of Shewanella oneidensis MR-1. For mineral respiring organisms there is the additional challenge of transferring the electrons from the cell to mineral surface. For the strict anaerobe Geobacter sulfurreducens this requires electron transfer through conductive pili to associated cytochrome OmcS that directly reduces Fe(III)oxides, while the facultative anaerobe S. oneidensis MR-1 accomplishes mineral reduction through direct membrane contact, contact through filamentous extentions and soluble flavin shuttles, all of which require the outer membrane cytochromes MtrC and OmcA in addition to secreted flavin

    The “E3D+VET” Erasmus+ project: Interdisciplinary teaching and learning in VET centres through 3D printing

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    The "E3D+VET" (Erasmus+ for the immersion in 3D printing of VET centres) is an Erasmus+ KA2 project aimed at developing educational resources for the VET system, providing new competences to both teachers and students and serving as important means of innovation and acquisition of effective knowledge on interdisciplinary STEAM topics. The project started on October 2017 and it will last up to the end of March 2020. In this work, we present the main outcomes from the project activities carried out so far. In particular, after a description of the general objectives of the project, we introduce the methodology developed for making 3D-printing a valuable resource for supporting physics teaching in a highly motivating learning environment and three didactical exercises as examples of 3D-printing based tools that can support teachers in their physics class. As a part of the project plan, here we finally present the preliminary training program specifically designed for the teacher professional development about the knowledge of 3D-printing potential for an effective teaching of physics contents and, at the same time, for improving student transversal abilities

    Long-Term Outcome of Repetitive Transcranial Magnetic Stimulation in a Large Cohort of Patients With Cocaine-Use Disorder: An Observational Study

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    Background: Cocaine is a psychostimulant drug used as performance enhancer throughout history. The prolonged use of cocaine is associated with addiction and a broad range of cognitive deficits. Currently, there are no medications proven to be effective for cocaine-use disorder (CocUD). Previous preliminary clinical work suggests some benefit from repetitive transcranial magnetic stimulation (rTMS) stimulating the prefrontal cortex (PFC), involved in inhibitory cognitive control, decision-making and attention. All published studies to date have been limited by small sample sizes and short follow-up times. Methods: This is a retrospective observational study of 284 outpatients (of whom 268 were men) meeting DSM-5 criteria for CocUD. At treatment entry, most were using cocaine every day or several times per week. All patients underwent 3 months of rTMS and were followed for up to 2 years, 8 months. Self-report, reports by family or significant others and regular urine screens were used to assess drug use. Results: Median time to the first lapse (resumption of cocaine use) since the beginning of treatment was 91 days. For most patients, TMS was re-administered weekly, then monthly, throughout follow-up. The decrease in frequency of rTMS sessions was not accompanied by an increase in lapses to cocaine use. Mean frequency of cocaine use was <1·0 day/month (median 0), while serious rTMS-related adverse events were infrequent, consistent with published reports from smaller studies. Conclusions: This is the first follow-up study to show that rTMS treatment is accompanied by long-lasting reductions in cocaine use in a large cohort

    Outbreak Of NDM-1-producing Klebsiella Pneumoniae In A Neonatal Unit In Colombia

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    Six multiresistant, NDM-1-producing Klebsiella pneumoniae strains were recovered from an outbreak that affected six neonatal patients in a Colombian hospital. Molecular analysis showed that all of the isolates harbored the blaNDM-1, qnrA, and intI1 genes and were clonally related. Multilocus sequence typing showed that the isolates belonged to a new sequence type (ST1043) that was different from the sequence types that had previously been reported. This is the first report of NDM-1-producing isolates in South America

    Biomarkers predicting the controller dose of omalizumab in patients with chronic spontaneous urticaria

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    Background Clinical trials showed the efficacy of 300 mg/4 weeks of omalizumab (OMA) during 6 months in patients with severe chronic spontaneous urticaria (CSU). Nevertheless, in real life, many patients require higher doses and/or longer treatment. This study assesses the real-life performance of OMA in severe CSU and identifies factors associated with the response. Methods CSU patients eligible for OMA were recruited prospectively. Clinical data and a blood test were collected before OMA initiation. Urticaria Activity Score 7 (UAS7) was calculated at baseline and every 3 months during OMA treatment. CSU control was defined as UAS7 <7 points. This work was partially sponsored by OMA manufacturer. Results Eighty-nine adults (19.1% males) with severe CSU were recruited. Median duration of CSU prior to OMA initiation was 2 years, and median severity by UAS7 at baseline was 24 points (range 10–42 points). OMA controlled 94.4% of patients, but 17.9% of responders required doses >300 mg/4 weeks. A blood basophil count >20 cells/μL (OR 13.33; 95% CI 3.32–52.63; p 29 months at the end of the study (active responders, AR). AR had received OMA for a median of 45 months (30–100 months). There were no significant differences in clinical or analytical factors between RR and AR patients. Conclusions Low blood basophil count and the presence of hypothyroidism might serve as biomarkers for the controller dose of OMA in severe CSU patients.Funding for open Access charge: Universidad de Málaga / CBUA. Instituto de Salud Carlos III; Novartis Pharmaceuticals Corporation; Consejería de Salud y Bienestar Social, Junta de Andalucí

    The impact of a large object with Jupiter in July 2009

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    On 2009 July 19, we observed a single, large impact on Jupiter at a planetocentric latitude of 55^{\circ}S. This and the Shoemaker-Levy 9 (SL9) impacts on Jupiter in 1994 are the only planetary-scale impacts ever observed. The 2009 impact had an entry trajectory opposite and with a lower incidence angle than that of SL9. Comparison of the initial aerosol cloud debris properties, spanning 4,800 km east-west and 2,500 km north-south, with those produced by the SL9 fragments, and dynamical calculations of pre-impact orbit, indicate that the impactor was most probably an icy body with a size of 0.5-1 km. The collision rate of events of this magnitude may be five to ten times more frequent than previously thought. The search for unpredicted impacts, such as the current one, could be best performed in 890-nm and K (2.03-2.36 {\mu}m) filters in strong gaseous absorption, where the high-altitude aerosols are more reflective than Jupiter's primary cloud.Comment: 15 pages, 5 figure

    Fear of non-employability and of economic crisis increaseworkplace harassment through lower organizational welfare orientation

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    There is a growing body of evidence suggesting that economic crisis is a preeminent stressor (i.e., economic stress) that may worsen working conditions and expose individuals to negative acts at work (i.e., workplace bullying). Following an occupational health perspective that considers contextual factors as risk factors for workplace bullying, this study aims to examine the mediation effects of organizational orientation to employee welfare in the economic stress-workplace bullying relationship. A cross-sectional study with the participation of 1004 Italian workers from several organizations was conducted. Our results indicate that economic stress (composed of two dimensions: fear of the economic crisis and perceived non-employability) is associated with workplace bullying through the total mediation of organizational orientation to employee welfare. These results have relevant implications for psychosocial risk assessment in turbulent times
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