349 research outputs found
Mass segregation in the young open cluster NGC 2547
We present a study of mass segregation of the young (20-35 Myr isochronal
age), open cluster NGC 2547. We find good evidence that mass segregation exists
in NGC 2547 down to 3 Msun, and weak evidence for mass segregation down to 1
Msun. Theoretical models of an initially unsegregated model of NGC 2547 using
the NBODY2 code show weaker mass segregation, implying that at least some of
the observed mass segregation has a primordial origin. We also report the
discovery of three possible escaped cluster members, which share the proper
motion and colours of the cluster, but lie nearly a degree from the cluster
centre.Comment: 7 pages, 7 figures. To appear in Monthly Notices (in press
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Ophrys fusca and Ophrys dyris (Orchidaceae) â constancy of tetraploidy amongst populations in Central Portugal
Ophrys is amongst the best known orchid genera and is an established system for the study of pollinatormediated
floral evolution. Two species, Ophrys fusca s.l. and Ophrys dyris (= O. omegaifera subsp. dyris) belonging to Ophrys section Pseudophrys are the focus of this study. In the context of an integrative study of morphological and genetic diversity of O. fusca and O. dyris, genome size (GS) and cytotype diversity were surveyed from Portuguese populations. Flow cytometry methods were used to assess GS, and subsequently determine the ploidy level of 67 specimens, including the species and putative hybrids. Cytotypes were also confirmed based on chromosome counts from the roots of two specimens, one of
each species. Constancy of nuclear DNA content (1C = 11.19 pg) and ploidy level (2n =4x = 72, 74) was
documented among all the individuals analysed. Implications are considered, in terms of interpreting the
origin and predicting the persistence of putative hybrids
Occupational sex-segregation, specialized human capital and wages: evidence from Britain
Female-dominated occupations are poorly paid, but there is disagreement about why. Sociological explanations argue that pay in such occupations is low because society undervalues 'women's work', while economic theory argues that this is due to scant requirements for specialized skills. This article sheds light over these debates by examining the impact of occupational feminization on wages in Britain and exploring the mechanisms that produce it, using innovative statistical models that account for both observable and unobservable skill. Results confirm that occupational sex-segregation explains a sizeable portion of the gender wage gap and that wages in female-dominated occupations are lower than wages in other occupations. Inconsistent with human capital theory, low pay in female-dominated occupations cannot be explained fully by low skill specialization or by observable or unobservable characteristics of their workers. Remaining wage penalties in such occupations are consequently taken as evidence of institutional devaluation of 'women's work'
A pilot study evaluating GSK1070806 inhibition of interleukin-18 in renal transplant delayed graft function.
INTRODUCTION: Delayed graft function (DGF) following renal transplantation is a manifestation of acute kidney injury (AKI) leading to poor long-term outcome. Current treatments have limited effectiveness in preventing DGF. Interleukin-18 (IL18), a biomarker of AKI, induces interferon-Îł expression and immune activation. GSK1070806, an anti-IL18 monoclonal antibody, neutralizes activated (mature) IL18 released from damaged cells following inflammasome activation. This phase IIa, single-arm trial assessed the effect of a single dose of GSK1070806 on DGF occurrence post donation after circulatory death (DCD) kidney transplantation. METHODS: The 3 mg/kg intravenous dose was selected based on prior studies and physiologically based pharmacokinetic (PBPK) modeling, indicating the high likelihood of a rapid and high level of IL18 target engagement when administered prior to kidney allograft reperfusion. Utilization of a Bayesian sequential design with a background standard-of-care DGF rate of 50% based on literature, and confirmed via extensive registry data analyses, enabled a statistical efficacy assessment with a minimal sample size. The primary endpoint was DGF frequency, defined as dialysis requirement â€7 days post transplantation (except for hyperkalemia). Secondary endpoints included safety, pharmacokinetics and pharmacodynamic biomarkers. RESULTS: GSK1070806 administration was associated with IL18-GSK1070806 complex detection and increased total serum IL18 levels due to IL18 half-life prolongation induced by GSK1070806 binding. Interferon-Îł-induced chemokine levels declined or remained unchanged in most patients. Although the study was concluded prior to the Bayesian-defined stopping point, 4/7 enrolled patients (57%) had DGF, exceeding the 50% standard-of-care rate, and an additional two patients, although not reaching the protocol-defined DGF definition, demonstrated poor graft function. Six of seven patients experienced serious adverse events (SAEs), including two treatment-related SAEs. CONCLUSION: Overall, using a Bayesian design and extensive PBPK dose modeling with only a small sample size, it was deemed unlikely that GSK1070806 would be efficacious in preventing DGF in the enrolled DCD transplant population. TRIAL REGISTRATION: NCT02723786
Cruise Report Poseidon 229a/b Kolbeinsey Ridge, Akureyri - Reykjavik, 22.05.1997 - 11.06.1997
General Subject of research: Detailed study of the shallow water hydrothermal system around Kolbeinsey and Grimsey island
Enduring Legacy? Charles Tilly and Durable Inequality
This article assesses Charles Tillyâs Durable Inequality and traces its influence. In writing Durable Inequality, Tilly sought to shift the research agenda of stratification scholars. But the bookâs initial impact was disappointing. In recent years, however, its influence has grown, suggesting a more enduring legacy
The Great Separation: Top Earner Segregation at Work in High-Income Countries
Analyzing linked employer-employee panel administrative databases, we study the evolving isolation of higher earners from other employees in eleven countries: Canada, Czechia, Denmark, France, Germany, Hungary, Japan, Norway, Spain, South Korea, and Sweden. We find in almost all countries a growing workplace isolation of top earners and dramatically declining exposure of top earners to bottom earners. We compare these trends to segregation based on occupational class, education, age, gender, and nativity, finding that the rise in top earner isolation is much more dramatic and general across countries. We find that residential segregation is also growing, although more slowly than segregation at work, with top earners and bottom earners increasingly living in different distinct municipalities. While work and residential segregation are correlated, statistical modeling suggests that the primary causal effect is from work to residential segregation. These findings open up a future research program on the causes and consequences of top earner segregation.En nous appuyant sur des donnĂ©es administratives longitudinales employeurâemployĂ©s, nous analysons lâĂ©volution de la sĂ©grĂ©gation sociale des salariĂ©s Ă hauts salaires dans onze pays: Allemagne, Canada, CorĂ©e du Sud, Danemark, Espagne, France, Hongrie, Japon, NorvĂšge, RĂ©publique tchĂšque et SuĂšde. Nous constatons dans presque tous les pays une forte augmentation de lâentre soi des salariĂ©s bien payĂ©s sur le lieu de travail et une diminution spectaculaire de leur exposition aux bas salaires. Nous comparons ces tendances Ă lâĂ©volution de la sĂ©grĂ©gation fondĂ©e sur la catĂ©gorie sociale, lâĂ©ducation, lâĂąge, le sexe et le statut migratoire, et nous constatons que lâaugmentation de lâentre soi des hauts salaires est celle qui est la plus prononcĂ©e et la plus gĂ©nĂ©rale. Nous montrons que la sĂ©grĂ©gation rĂ©sidentielle se dĂ©veloppe aussi, bien que plus lentement que la sĂ©grĂ©gation au travail, avec les hauts et les bas salaires vivant de plus en plus dans des municipalitĂ©s distinctes. SĂ©grĂ©gation au travail et sĂ©grĂ©gation rĂ©sidentielle sont corrĂ©lĂ©es. Mais nos modĂšles statistiques suggĂšrent aussi que la principale relation de causalitĂ© va de la sĂ©grĂ©gation au travail vers la sĂ©grĂ©gation rĂ©sidentielle. Ces rĂ©sultats ouvrent la voie Ă un futur programme de recherche sur les causes et les consĂ©quences de la sĂ©grĂ©gation des hauts salaires.1 Introduction 2 From ethnic residential segregation to earnings segregation at work 3 Administrative data for estimating exposure measures 4 A strong increase in earnings segregation at work 5 A robust trend 17 French robustness tests 6 A specific trend 7 The link between work and residential segregation 8 Elements for a research program on the causes and consequences of increasing segregation at work The roots of growing earnings segregation at work The consequences of growing earnings segregation at work Appendices A1 Data sources and sample definition A2 Demonstration of the symmetry of relative exposure gRh = hRg A3 Figure construction A4 French robustness checks Supplementary figures and tables Reference
New Insights into the mineralogy of the Atlantis II deep metalliferous sediments, Red Sea
The Atlantis II Deep of the Red Sea hosts the largest known hydrothermal ore deposit on the ocean floor and the only modern analog of brine pool-type metal deposition. The deposit consists mainly of chemical-clastic sediments with input from basin-scale hydrothermal and detrital sources. A characteristic feature is the millimeter-scale layering of the sediments, which bears a strong resemblance to banded iron formation (BIF). Quantitative assessment of the mineralogy based on relogging of archived cores, detailed petrography, and sequential leaching experiments shows that Fe-(oxy)hydroxides, hydrothermal carbonates, sulfides, and authigenic clays are the main âoreâ minerals. Mn-oxides were mainly deposited when the brine pool was more oxidized than it is today, but detailed logging shows that Fe-deposition and Mn-deposition also alternated at the scale of individual laminae, reflecting short-term fluctuations in the Lower Brine. Previous studies underestimated the importance of nonsulfide metal-bearing components, which formed by metal adsorption onto poorly crystalline Si-Fe-OOH particles. During diagenesis, the crystallinity of all phases increased, and the fine layering of the sediment was enhanced. Within a few meters of burial (corresponding to a few thousand years of deposition), biogenic (Ca)-carbonate was dissolved, manganosiderite formed, and metals originally in poorly crystalline phases or in pore water were incorporated into diagenetic sulfides, clays, and Fe-oxides. Permeable layers with abundant radiolarian tests were the focus for late-stage hydrothermal alteration and replacement, including deposition of amorphous silica and enrichment in elements such as Ba and Au
Tectonic and magmatic controls on hydrothermal activity in the Woodlark Basin
The Woodlark Basin is one of the rare places on earth where the transition from continental breakup to seafloor spreading can be observed. The potential juxtaposition of continental rocks, a large magmatic heat source, crustal-scale faulting, and hydrothermal circulation has made the Woodlark Basin a prime target for seafloor mineral exploration. However, over the past 20 years, only two locations of active hydrothermalism had been found. In 2009 we surveyed 435 km of the spreading axis for the presence of hydrothermal plumes. Only one additional plume was found, bringing the total number of plumes known over 520 km of ridge axis to only 3, much less than at ridges with similar spreading rates globally. Particularly the western half of the basin (280 km of axis) is apparently devoid of high temperature plumes despite having thick crust and a presumably high magmatic budget. This paucity of hydrothermal activity may be related to the peculiar tectonic setting at Woodlark, where repeated ridge jumps and a re-location of the rotation pole both lead to axial magmatism being more widely distributed than at many other, more mature and stable mid-ocean ridges. These factors could inhibit the development of both a stable magmatic heat source and the deeply penetrating faults needed to create long-lived hydrothermal systems. We conclude that large seafloor massive sulfide deposits, potential targets for seafloor mineral exploration, will probably not be present along the spreading axis of the Woodlark Basin, especially in its younger, western portion
Introductory programming: a systematic literature review
As computing becomes a mainstream discipline embedded in the school curriculum and acts as an enabler for an increasing range of academic disciplines in higher education, the literature on introductory programming is growing. Although there have been several reviews that focus on specific aspects of introductory programming, there has been no broad overview of the literature exploring recent trends across the breadth of introductory programming.
This paper is the report of an ITiCSE working group that conducted a systematic review in order to gain an overview of the introductory programming literature. Partitioning the literature into papers addressing the student, teaching, the curriculum, and assessment, we explore trends, highlight advances in knowledge over the past 15 years, and indicate possible directions for future research
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