1,455 research outputs found

    UV/Ozone treatment to reduce metal-graphene contact resistance

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    We report reduced contact resistance of single-layer graphene devices by using ultraviolet ozone (UVO) treatment to modify the metal/graphene contact interface. The devices were fabricated from mechanically transferred, chemical vapor deposition (CVD) grown, single layer graphene. UVO treatment of graphene in the contact regions as defined by photolithography and prior to metal deposition was found to reduce interface contamination originating from incomplete removal of poly(methyl methacrylate) (PMMA) and photoresist. Our control experiment shows that exposure times up to 10 minutes did not introduce significant disorder in the graphene as characterized by Raman spectroscopy. By using the described approach, contact resistance of less than 200 {\Omega} {\mu}m was achieved, while not significantly altering the electrical properties of the graphene channel region of devices.Comment: 17 pages, 5 figure

    A Disk Shadow Around the Young Star ASR 41 in NGC 1333

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    We present images of the young stellar object ASR 41 in the NGC 1333 star forming region at the wavelengths of H_alpha and [SII] and in the I, J, H, and K-bands. ASR 41 has the near-infrared morphology of an edge-on disk object, but appears an order of magnitude larger than typical systems of this kind. We also present detailed models of the scattering and radiative transfer in systems consisting of a young star surrounded by a proto-planetary disk, and the whole system being embedded in either an infalling envelope or a uniform molecular cloud. The best fit to the observed morphology can be achieved with a disk of approx. 200 AU diameter, immersed in a low density cloud. The low cloud density is necessary to stay below the sub-mm flux upper limits and to preserve the shadow cast by the disk via single scattering. The results demonstrate that ASR 41 is probably not inherently different from typical edge-on disk objects, and that its large apparent size is due to the shadow of a much smaller disk being projected into the surrounding dusty molecular material

    Evolution of prokaryotic SPFH proteins

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    BACKGROUND: The SPFH protein superfamily is a diverse family of proteins whose eukaryotic members are involved in the scaffolding of detergent-resistant microdomains. Recently the origin of the SPFH proteins has been questioned. Instead, convergent evolution has been proposed. However, an independent, convergent evolution of three large prokaryotic and three eukaryotic families is highly unlikely, especially when other mechanisms such as lateral gene transfer which could also explain their distribution pattern have not yet been considered.To gain better insight into this very diverse protein family, we have analyzed the genomes of 497 microorganisms and investigated the pattern of occurrence as well as the genomic vicinity of the prokaryotic SPFH members. RESULTS: According to sequence and operon structure, a clear division into 12 subfamilies was evident. Three subfamilies (SPFH1, SPFH2 and SPFH5) show a conserved operon structure and two additional subfamilies are linked to those three through functional aspects (SPFH1, SPFH3, SPFH4: interaction with FtsH protease). Therefore these subgroups most likely share common ancestry. The complex pattern of occurrence among the different phyla is indicative of lateral gene transfer. Organisms that do not possess a single SPFH protein are almost exclusively endosymbionts or endoparasites. CONCLUSION: The conserved operon structure and functional similarities suggest that at least 5 subfamilies that encompass almost 75% of all prokaryotic SPFH members share a common origin. Their similarity to the different eukaryotic SPFH families, as well as functional similarities, suggests that the eukaryotic SPFH families originated from different prokaryotic SPFH families rather than one. This explains the difficulties in obtaining a consistent phylogenetic tree of the eukaryotic SPFH members. Phylogenetic evidence points towards lateral gene transfer as one source of the very diverse patterns of occurrence in bacterial species

    Hsf1 and Hsp90 orchestrate temperature-dependent global transcriptional remodelling and chromatin architecture in Candida albicans

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    We thank Karim Gharbi and Urmi Trivedi for their assistance with RNA sequencing, carried out in the GenePool genomics facility (University of Edinburgh). We also thank Susan Fairley and Eduardo De Paiva Alves (Centre for Genome Enabled Biology and Medicine, University of Aberdeen) for help with the initial bioinformatics analysis. We thank Aaron Mitchell for kindly providing the ALS3 mutant, Julian Naglik for the gift of TR146 cells, and Jon Richardson for technical assistance. We thank the Genomics and Bioinformatics core of the Faculty of Health Sciences for Next Generation Sequencing and Bioinformatics support, the Information and Communication Technology Office at the University of Macau for providing access to a High Performance Computer and Jacky Chan and William Pang for their expert support on the High Performance Computer. Finally, we thank Amanda Veri for generating CaLC2928. M.D.L. is supported by a Sir Henry Wellcome Postdoctoral Fellowship (Wellcome Trust 096072), R.A.F. by a Wellcome Trust-Massachusetts Institute of Technology (MIT) Postdoctoral Fellowship, L.E.C. by a Canada Research Chair in Microbial Genomics and Infectious Disease and by Canadian Institutes of Health Research Grants MOP-119520 and MOP-86452, A.J. P.B. was supported by the UK Biotechnology and Biological Sciences Research Council (BB/F00513X/1) and by the European Research Council (ERC-2009-AdG-249793-STRIFE), KHW is supported by the Science and Technology Development Fund of Macau S.A.R (FDCT) (085/2014/A2) and the Research and Development Administrative Office of the University of Macau (SRG2014-00003-FHS) and R.T.W. by the Burroughs Wellcome fund and NIH R15AO094406. Data availability RNA-sequencing data sets are available at ArrayExpress (www.ebi.ac.uk) under accession code E-MTAB-4075. ChIP-seq data sets are available at the NCBI SRA database (http://www.ncbi.nlm.nih.gov) under accession code SRP071687. The authors declare that all other data supporting the findings of this study are available within the article and its supplementary information files, or from the corresponding author upon request.Peer reviewedPublisher PD

    Binge flying: Behavioural addiction and climate change

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    Recent popular press suggests that ‘binge flying’ constitutes a new site of behavioural addiction. We theoretically appraise and empirically support this proposition through interviews with consumers in Norway and the United Kingdom conducted in 2009. Consistent findings from across two national contexts evidence a growing negative discourse towards frequent short-haul tourist air travel and illustrate strategies of guilt suppression and denial used to span a cognitive dissonance between the short-term personal benefits of tourism and the air travel’s associated long-term consequences for climate change. Tensions between tourism consumption and changing social norms towards acceptable flying practice exemplify how this social group is beginning to (re)frame what constitutes ‘excessive’ holiday flying, despite concomitantly continuing their own frequent air travels

    DNA Extraction Method Development for Ocular Tissues

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    Purpose: DNA extraction kits are traditionally developed to work with liquid tissues such as blood, saliva, and swabs, but some have been proposed to work with solid tissues. Somatic variation in cancers can be important for tumor subtyping and treatment guidance, including ocular tumors. Additionally, epigenetic marks such as 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are tissue-specific and change in disease states, particularly evident in diabetic retinopathy and age-related macular degeneration. Commercial DNA extraction kits are available from several vendors, but the various kits have different strengths and weaknesses, and the removal of PCR inhibitors will vary with each kit. This project investigates the yield and purity of DNA from ocular tissues using commercial DNA extraction kits. Methods: Cornea, neural retina, RPE/choroid layer, optic nerve, and capsular bag were collected and aliquoted into 15 mg aliquots. Extractions were performed using the following kits: DNEasy Blood and Tissue Kit (Qiagen;), GeneJET Genomic DNA Purification Kit (ThermoFisher Scientific), Monarch HMW DNA Extraction Kit for Tissue (New England Biosciences), and genomicPrep Mini Spin Kit (Cytiva). DNA was quantified using the Qubit Fluorometer and molecular weight was checked by agarose gel. Several more kits are currently being tested. Results: All four kits yielded high molecular weight DNA (above 20 kbp). The Monarch HMW kit yielded DNA with significantly higher molecular weights. The DNA yields per milligram of tissue were highest using the DNEasy Blood and Tissue Kit for optic nerve, neural retina, and RPE/choroid. The yield was highest for the cornea using the genomicPrep Mini Spin Kit. Only the genomicPrep Mini Spin Kit yielded sufficient DNA for quantification from the capsular bag, and total yields were minimal (600 ng or less). Additional kits are currently being tested, but initial results indicate that several commercial kits will be sufficient for DNA extraction of ocular tissues. Further work is needed to purify epithelial cells and stem cells from the intraocular lens. Conclusions: Of the kits tested, all are sufficient to obtain significant amounts of DNA from all ocular tissues aside from the capsular bag. The Monarch HMW yielded the highest molecular weight, but significantly lower quantities of DNA than the other kits, indicating that it may not be ideal for most purposes. Protocol development for the capsular bag is still underway

    Efficacy and safety of co-careldopa as an add-on therapy to occupational and physical therapy in patients after stroke (DARS): a randomised, double-blind, placebo controlled trial

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    Background Dopamine is a key modulator of striatal function and learning and might improve motor recovery after stroke. Previous small trials of dopamine agonists after stroke provide equivocal evidence of effectiveness on improving motor recovery. We aimed to assess the safety and efficacy of co-careldopa plus routine occupational and physical therapy during early rehabilitation after stroke. Methods This double-blind, multicentre, randomised controlled trial of co-careldopa versus placebo in addition to routine NHS occupational and physical therapy was done at 51 UK NHS acute inpatient stroke rehabilitation services. We recruited patients with new or recurrent clinically diagnosed ischaemic or haemorrhagic (excluding subarachnoid haemorrhage) stroke 5–42 days before randomisation, who were unable to walk 10 m or more, had a score of less than 7 points on the Rivermead Mobility Index, were expected to need rehabilitation, and were able to access rehabilitation after discharge from hospital. Participants were assigned (1:1) using stratified random blocks to receive 6 weeks of oral co-careldopa or matched placebo in addition to routine NHS physiotherapy and occupational therapy. The initial two doses of co-careldopa were 62·5 mg (50 mg of levodopa and 12·5 mg of carbidopa) and the remaining doses were 125 mg (100 mg of levodopa and 25 mg of carbidopa). Participants were required to take a single oral tablet 45–60 min before physiotherapy or occupational therapy session. The primary outcome was ability to walk independently, defined as a Rivermead Mobility Index score of 7 or more, at 8 weeks. Primary and safety analyses were done in the intention-to-treat population. The trial is registered on the ISRCTN registry, number ISRCTN99643613.Findings Between May 30, 2011, and March 28, 2014, of 1574 patients found eligible, 593 (mean age 68·5 years) were randomly assigned to either the co-careldopa group (n=308) or to the placebo group (n=285), on an average 18 days after stroke onset. Primary outcome data were available for all 593 patients. We found no evidence that the ability to walk independently improved with co-careldopa (125 [41%] of 308 patients) compared with placebo (127 [45%] of 285 patients; odds ratio 0·78 [95% CI 0·53–1·15]) at 8 weeks. Mortality at 12 months did not differ between the two groups (22 [7%] vs 17 [6%]). Serious adverse events were largely similar between groups. Vomiting during therapy sessions, after taking the study drug, was the most frequent adverse event and was more frequent in the co-careldopa group than the placebo group (19 [6·2%] vs 9 [3·2%]).Interpretation Co-careldopa in addition to routine occupational and physical therapy does not seem to improve walking after stroke. Further research might identify subgroups of patients with stroke who could benefit from dopaminergic therapy at different doses or times after stroke with more intensive motor therap
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