684 research outputs found

    Possible pseudogap behavior of electron doped high-temperature superconductors

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    We have measured the low-energy quasiparticle excitation spectrum of the electron doped high-temperature superconductors (HTS) Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1.85)Ce(0.15)CuO(4-y) as a function of temperature and applied magnetic field using tunneling spectroscopy. At zero magnetic field, for these optimum doped samples no excitation gap is observed in the tunneling spectra above the transition temperature Tc. In contrast, below Tc for applied magnetic fields well above the resistively determined upper critical field, a clear excitation gap at the Fermi level is found which is comparable to the superconducting energy gap below Tc. Possible interpretations of this observation are the existence of a normal state pseudogap in the electron doped HTS or the existence of a spatially non-uniform superconducting state.Comment: 4 pages, 4 ps-figures included, to be published in Phys. Rev. B, Rapid Com

    Kinetic alteration of the 6Mg(NH2)2-9LiH-LiBH4 system by co-adding YCl3 and Li3N

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    The 6Mg(NH2)2-9LiH-LiBH4 composite system has a maximum reversible hydrogen content of 4.2 wt% and a predicted dehydrogenation temperature of about 64 °C at 1 bar of H2. However, the existence of severe kinetic barriers precludes the occurrence of de/re-hydrogenation processes at such a low temperature (H. Cao, G. Wu, Y. Zhang, Z. Xiong, J. Qiu and P. Chen, J. Mater. Chem. A, 2014, 2, 15816-15822). In this work, Li3N and YCl3 have been chosen as co-additives for this system. These additives increase the hydrogen storage capacity and hasten the de/re-hydrogenation kinetics: a hydrogen uptake of 4.2 wt% of H2 was achieved in only 8 min under isothermal conditions at 180 °C and 85 bar of H2 pressure. The re-hydrogenation temperature, necessary for a complete absorption process, can be lowered below 90 °C by increasing the H2 pressure above 185 bar. Moreover, the results indicate that the hydrogenation capacity and absorption kinetics can be maintained roughly constant over several cycles. Low operating temperatures, together with fast absorption kinetics and good reversibility, make this system a promising on-board hydrogen storage material. The reasons for the improved de/re-hydrogenation properties are thoroughly investigated and discussed

    Ambivalent improvements: biography, biopolitics, and colonial Delhi

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    This paper explores the ambivalent feelings towards the Government of India produced in one of the government’s own employees. In establishing the Delhi Improvement Trust in the 1930s, Arthur Parke Hume had to battle against governmental cost cutting in an attempt to secure the rehousing of slum evictees. The refusal of the government to accept this welfarist commitment to investment led to the stalling of the improvement projects and great emotional disquiet for Hume. This is traced through his personal correspondence with his parents. In interweaving these insights with the imperial archive, three biographical approaches are adopted. A traditional chronology is used to order the events, an analytical approach is used to outline the discursive regularities of Hume’s observations, and a genealogical approach is used to suggest the influences on Hume’s writings and the broader governmental rationalities that he had to negotiate

    Clinical effectiveness of unilateral deep brain stimulation in Tourette syndrome

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    Dysfunctional basal ganglia loops are thought to underlie the clinical picture of Tourette syndrome (TS). By altering dopaminergic activity in the affected neural structures, bilateral deep brain stimulation is assumed to have a modulatory effect on dopamine transmission resulting in an amelioration of tics. While the majority of published case reports deals with the application of bilateral stimulation, the present study aims at informing about the high effectiveness of unilateral stimulation of pallidal and nigral thalamic territories in TS. Potential implications and gains of the unilateral approach are discussed

    Allele-specific miRNA-binding analysis identifies candidate target genes for breast cancer risk

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    Most breast cancer (BC) risk-associated single-nucleotide polymorphisms (raSNPs) identified in genome-wide association studies (GWAS) are believed to cis-regulate the expression of genes. We hypothesise that cis-regulatory variants contributing to disease risk may be affecting microRNA (miRNA) genes and/or miRNA binding. To test this, we adapted two miRNA-binding prediction algorithms-TargetScan and miRanda-to perform allele-specific queries, and integrated differential allelic expression (DAE) and expression quantitative trait loci (eQTL) data, to query 150 genome-wide significant ( P≤5×10-8 ) raSNPs, plus proxies. We found that no raSNP mapped to a miRNA gene, suggesting that altered miRNA targeting is an unlikely mechanism involved in BC risk. Also, 11.5% (6 out of 52) raSNPs located in 3'-untranslated regions of putative miRNA target genes were predicted to alter miRNA::mRNA (messenger RNA) pair binding stability in five candidate target genes. Of these, we propose RNF115, at locus 1q21.1, as a strong novel target gene associated with BC risk, and reinforce the role of miRNA-mediated cis-regulation at locus 19p13.11. We believe that integrating allele-specific querying in miRNA-binding prediction, and data supporting cis-regulation of expression, improves the identification of candidate target genes in BC risk, as well as in other common cancers and complex diseases.Funding Agency Portuguese Foundation for Science and Technology CRESC ALGARVE 2020 European Union (EU) 303745 Maratona da Saude Award DL 57/2016/CP1361/CT0042 SFRH/BPD/99502/2014 CBMR-UID/BIM/04773/2013 POCI-01-0145-FEDER-022184info:eu-repo/semantics/publishedVersio

    Performance of resistant varieties (PIWI) at two different altitudes in Southern Brazil

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    In southern Brazil there is a predominance of labrusca and hybrid varieties for wine and juice production due to climatic conditions of high rainfall, temperature and relative humidity. Growing varieties that combine disease resistance and wine quality (PIWI) can be an alternative to improve wine quality. The objective of this work was to evaluate the performance of three PIWI varieties (Felicia, Calardis Blanc and Aromera) in two regions (Videira, 27∘01′S and 51∘08′W, altitude 830 m; and São Joaquim, 28∘13′S and 50∘04′W, altitude 1100 m) in the vintage 2018. The date of occurrence of main phenological stages, productiveindexes, clusters characteristics and grape qualitative indexes was evaluated. There was no difference for budbreak date, but flowering, veraison an maturity time varied between regions. The development of plants is slower when they are cultivated at a higher altitude. The number of clusters per plant and yield were higher at 830 m for all varieties. For productive indexes Felicia and Calardis Blanc varieties stood out in relation to Aromera in all parameters. Among the evaluated varieties, Felicia and Calardis Blanc were better adapted to the lower altitude region and had higher productivity and the same grape quality. On the other hand, Aromera presented higher productivity at 830 m but higher soluble solids content at 1100 m
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