Compressive and tensile axial strain reduced critical currents in Bi-2212 conductors

Mono and multifilamentary wires of BSCCO-2212 in Ag matrix are investigated in an axial strain experiment. The superconducting samples are soldered to a substrate that is bend in order to achieve a compressive or tensile axial strain. The I/sub c/-strain dependence is measured in magnetic fields up to 16 T at 4.2 K and the strain is varied from -2% to +1.2%. In these Bi-2122 samples any strain-induced I/sub c/ reduction is irreversible. Moreover a significant rise in I/sub c/ was never observed after changing the strain. Special attention is paid to the tensile axial strain regime (0 to 0.4%). A small but significant reduction in I/sub c/ is found in this case. The strain behaviour of these wires indicates that the I/sub c/ reduction is due to fractures in the superconducting filament

Transport current dependence of the hysterisis loss in silver sheathed BSCCO-2212 conductors

A technique is described to study the critical current density and penetration fieldassociated with the transport current in a silver sheathed BSCCO conductor. A transport current flowing in a conductor in a varying magnetic field will only influence magnetisation currents that are in competition with the transport current, i.e. currents that use the same path. By measuring the transport current dependence of the magnetisation loss information can be obtained on the related critical current and penetration field. The combination of these two quantities contains information about the geometry of the current distribution and can be used to test different models for the current distribution in BSCCO conductors

Comparing powder magnetization and transport critical current of Bi,Pb(2223) tapes

The magnetic field dependence of the critical current in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+x/ tapes is compared with the magnetization response of isolated grains extracted from the tapes. Special attention is paid to the low-field behavior. The goal of the experiment is to test the widely-used hypothesis that current paths in these tapes contain both weak- and strong- linked branches, which in low field act in parallel. The data agree with this hypothesis; at temperatures above 50 K the powder magnetization drops off exponentially from the self-field to the irreversibility field, while the transport and magnetization currents in the intact tapes show an extra low-field component. Below 50 K the powder behavior becomes less straightforward, but the parallel-path picture in the tapes still holds

Strain effects in high temperature superconductors investigated with magneto-optical imaging

In order to determine the influence of intermediate deformation steps on the mechanical behavior of Bi-based tapes, the effect of longitudinal applied strain is investigated by means of magneto-optical imaging. The strain is applied in a helium flow-cryostat. Cracks appear soon after the critical current in Bi-based tapes is degraded. All filaments form multiple cracks that grow into tape-wide cracks, running from one filament to the next. The crack location is not caused by stress concentrations in the matrix, but by the mechanically weak colony boundaries. Because of the absence of intermediate rolling steps in the production of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ tapes, a different crack structure is observed compared to Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ tapes. The relation between the critical current and the formation of cracks is studied. The degradation in critical current before the critical strain is reached may be caused by microcracks that remain undetected by magneto-optical imaging. The influence of strain on the microstructure of YBa/sub 2/Cu/sub 3/O/sub x/ coated conductors is also investigated with magneto-optical imaging. The formation of cracks is believed to be determined by the nickel substrate and related to the Ni-grain size

The GATA-factor elt-2 is essential for formation of the Caenorhabditis elegans intestine

AbstractThe Caenorhabditis elegans elt-2 gene encodes a single-finger GATA factor, previously cloned by virtue of its binding to a tandem pair of GATA sites that control the gut-specific ges-1 esterase gene. In the present paper, we show that elt-2 expression is completely gut specific, beginning when the embryonic gut has only two cells (one cell cycle prior to ges-1 expression) and continuing in every cell of the gut throughout the life of the worm. When elt-2 is expressed ectopically using a transgenic heat-shock construct, the endogenous ges-1 gene is now expressed in most if not all cells of the embryo; several other gut markers (including a transgenic elt-2-promoter: lacZ reporter construct designed to test for elt-2 autoregulation) are also expressed ectopically in the same experiment. These effects are specific in that two other C. elegans GATA factors (elt-1 and elt-3) do not cause ectopic gut gene expression. An imprecise transposon excision was identified that removes the entire elt-2 coding region. Homozygous elt-2 null mutants die at the L1 larval stage with an apparent malformation or degeneration of gut cells. Although the loss of elt-2 function has major consequences for later gut morphogenesis and function, mutant embryos still express ges-1. We suggest that elt-2 is part of a redundant network of genes that controls embryonic gut development; other factors may be able to compensate for elt-2 loss in the earlier stages of gut development but not in later stages. We discuss whether elements of this regulatory network may be conserved in all metazoa

Effect of neoadjuvant chemoradiotherapy on health-Related quality of life in esophageal or junctional cancer: Results from the randomized CROSS trial

Purpose To compare pre-agreed health-related quality of life (HRQOL) domains in patients with esophageal or junctional cancer who received neoadjuvant chemoradiotherapy (nCRT) followed by surgery or surgery alone. Secondary aims were to examine the effect of nCRT on HRQOL before surgery and the effect of surgery on HRQOL. Patients and Methods Patients were randomly assigned to nCRT (carboplatin plus paclitaxel with concurrent 41.4-Gy radiotherapy) followed by surgery or surgery alone. HRQOL was measured using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire–Core 30 (QLQ-C30) and –Oesophageal Cancer Module (QLQ-OES24) questionnaires pretreatment and at 3, 6, 9, and 12 months postoperatively. The nCRT group also received preoperative questionnaires. Physical functioning (PF; QLQ-C30) and eating problems (EA; QLQ-OES24) were chosen as predefined primary end points. Predefined secondary end points were global QOL (GQOL; QLQ-C30), fatigue (FA; QLQ-C30), and emotional problems (EM; QLQ-OES24). Results A total of 363 patients were analyzed. No statistically significant differences in postoperative HRQOL were found between treatment groups. In the nCRT group, PF, EA, GQOL, FA, and EM scores deteriorated 1 week after nCRT (Cohen’s d: 20.93, P, .001; 0.47, P, .001; 20.84, P, .001; 1.45, P, .001; and 0.32, P = .001, respectively). In both treatment groups, all end points declined 3 months postoperatively compared with baseline (Cohen’s d: 21.00, 0.33, 20.47, 20.34, and 0.33, respectively; all P, .001), followed by a continuous gradual improvement. EA, GQOL, and EM were restored to baseline levels during follow-up, whereas PF and FA remained impaired 1 year postoperatively (Cohen’s d: 0.52 and 20.53, respectively; both P, .001). Conclusion Although HRQOL declined during nCRT, no effect of nCRT was apparent on postoperative HRQOL compared with surgery alone. In addition to the improvement in survival, these findings support the view that nCRT according to the Chemoradiotherapy for Esophageal Cancer Followed by Surgery Study–regimen can be regarded as a standard of care

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe