125 research outputs found
Crystal structure of solid Oxygen at high pressure and low temperature
Results of X-ray diffraction experiments on solid oxygen at low temperature
and at pressures up to 10 GPa are presented.A careful sample preparation and
annealing around 240 K allowed to obtain very good diffraction patterns in the
orthorhombic delta-phase. This phase is stable at low temperature, in contrast
to some recent data [Y. Akahama et al., Phys. Rev. B64, 054105 (2001)], and
transforms with decreasing pressure into a monoclinic phase, which is
identified as the low pressure alpha-phase. The discontinuous change of the
lattice parameters, and the observed metastability of the alpha-phase
increasing pressure suggest that the transition is of the first order.Comment: 4 pages with three figure
Coherent electron-phonon coupling and polaron-like transport in molecular wires
We present a technique to calculate the transport properties through
one-dimensional models of molecular wires. The calculations include inelastic
electron scattering due to electron-lattice interaction. The coupling between
the electron and the lattice is crucial to determine the transport properties
in one-dimensional systems subject to Peierls transition since it drives the
transition itself. The electron-phonon coupling is treated as a quantum
coherent process, in the sense that no random dephasing due to electron-phonon
interactions is introduced in the scattering wave functions. We show that
charge carrier injection, even in the tunneling regime, induces lattice
distortions localized around the tunneling electron. The transport in the
molecular wire is due to polaron-like propagation. We show typical examples of
the lattice distortions induced by charge injection into the wire. In the
tunneling regime, the electron transmission is strongly enhanced in comparison
with the case of elastic scattering through the undistorted molecular wire. We
also show that although lattice fluctuations modify the electron transmission
through the wire, the modifications are qualitatively different from those
obtained by the quantum electron-phonon inelastic scattering technique. Our
results should hold in principle for other one-dimensional atomic-scale wires
subject to Peierls transitions.Comment: 21 pages, 8 figures, accepted for publication in Phys. Rev. B (to
appear march 2001
Insulin-like growth factor 1 (IGF1), IGF binding protein 3 (IGFBP3), and breast cancer risk: Pooled individual data analysis of 17 prospective studies
Background: Insulin-like growth factor 1 (IGF1) stimulates mitosis and inhibits apoptosis. Some published results have shown an association between circulating IGF1 and breast-cancer risk, but it has been unclear whether this relationship is consistent or whether it is modified by IGF binding protein 3 (IGFBP3), menopausal status, oestrogen receptor status or other factors. The relationship of IGF1 (and IGFBP3) with breast-cancer risk factors is also unclear. The Endogenous Hormones and Breast Cancer Collaborative Group was established to analyse pooled individual data from prospective studies to increase the precision of the estimated associations of endogenous hormones with breast-cancer risk. Methods: Individual data on prediagnostic IGF1 and IGFBP3 concentrations were obtained from 17 prospective studies in 12 countries. The associations of IGF1 with risk factors for breast cancer in controls were examined by calculating geometric mean concentrations in categories of these factors. The odds ratios (ORs) with 95% CIs of breast cancer associated with increasing IGF1 concentrations were estimated by conditional logistic regression in 4790 cases and 9428 matched controls, with stratification by study, age at baseline, and date of baseline. All statistical tests were two-sided, and a p value of less than 0\ub705 was considered significant. Findings: IGF1 concentrations, adjusted for age, were positively associated with height and age at first pregnancy, inversely associated with age at menarche and years since menopause, and were higher in moderately overweight women and moderate alcohol consumers than in other women. The OR for breast cancer for women in the highest versus the lowest fifth of IGF1 concentration was 1\ub728 (95% CI 1\ub714-1\ub744; p<0\ub70001). This association was not altered by adjusting for IGFBP3, and did not vary significantly by menopausal status at blood collection. The ORs for a difference in IGF1 concentration between the highest and lowest fifth were 1\ub738 (95% CI 1\ub714-1\ub768) for oestrogen-receptor-positive tumours and 0\ub780 (0\ub757-1\ub713) for oestrogen-receptor-negative tumours (p for heterogeneity=0\ub7007). Interpretation: Circulating IGF1 is positively associated with breast-cancer risk. The association is not substantially modified by IGFBP3, and does not differ markedly by menopausal status, but seems to be confined to oestrogen-receptor-positive tumours
The criminal justice voluntary sector: concepts and an agenda for an emerging field
This is the peer reviewed version of the following article: Tomczak, P. & Buck, G. (2019). The criminal justice voluntary sector: concepts and an agenda for an emerging field. Howard Journal of Crime and Justice, 58(3), which has been published in final form at https://doi.org/10.1111/hojo.12326. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Volunteers and voluntary organisations play significant roles pervading criminal justice. They are key actors, with unrecognised potential to shore up criminal justice and/or collaboratively reshape social justice. Unlike public and for-profit agents, criminal justice volunteers and voluntary organisations (CJVVOs) have been neglected by scholars. We call for analyses of diverse CJVVOs, in national and comparative contexts. We provide three categories to highlight distinctive organising auspices, which hold across criminal justice: statutory volunteers, quasi-statutory volunteers and voluntary organisations. The unknown implications of these different forms of non-state, non-profit justice involvement deserve far greater attention from academics, policymakers and practitioners
Physical activity, sedentary time and breast cancer risk: a Mendelian randomisation study
Objectives: Physical inactivity and sedentary behaviour are associated with higher breast cancer risk in observational studies, but ascribing causality is difficult. Mendelian randomisation (MR) assesses causality by simulating randomised trial groups using genotype. We assessed whether lifelong physical activity or sedentary time, assessed using genotype, may be causally associated with breast cancer risk overall, pre/post-menopause, and by case-groups defined by tumour characteristics.
Methods: We performed two-sample inverse-variance-weighted MR using individual-level Breast Cancer Association Consortium case-control data from 130 957 European-ancestry women (69 838 invasive cases), and published UK Biobank data (n=91 105â377 234). Genetic instruments were single nucleotide polymorphisms (SNPs) associated in UK Biobank with wrist-worn accelerometer-measured overall physical activity (nsnps=5) or sedentary time (nsnps=6), or accelerometer-measured (nsnps=1) or self-reported (nsnps=5) vigorous physical activity.
Results: Greater genetically-predicted overall activity was associated with lower breast cancer overall risk (OR=0.59; 95% confidence interval (CI) 0.42 to 0.83 per-standard deviation (SD;~8 milligravities acceleration)) and for most case-groups. Genetically-predicted vigorous activity was associated with lower risk of pre/perimenopausal breast cancer (OR=0.62; 95% CI 0.45 to 0.87,â„3 vs. 0 self-reported days/week), with consistent estimates for most case-groups. Greater genetically-predicted sedentary time was associated with higher hormone-receptor-negative tumour risk (OR=1.77; 95% CI 1.07 to 2.92 per-SD (~7% time spent sedentary)), with elevated estimates for most case-groups. Results were robust to sensitivity analyses examining pleiotropy (including weighted-median-MR, MR-Egger).
Conclusion: Our study provides strong evidence that greater overall physical activity, greater vigorous activity, and lower sedentary time are likely to reduce breast cancer risk. More widespread adoption of active lifestyles may reduce the burden from the most common cancer in women
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