1,049 research outputs found

    40Ar/39Ar and U-Pb mineral ages from the Brookville Gneiss: implications for terrane analysis and evolution of Avalonian "basement" in southern New Brunswick

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    New 40Ar/39Ar hornblende and U-Pb zircon data from units previously thought to represent basement to the Avalon composite terrane in southern New Brunswick yield latest Precambrian or early Cambrian metamorphic cooling ages and a late Precambrian protolith age. Hornblendes from the Brookville Gneiss and from an intrusive amphibolite body within the gneiss yield 40Ar/39Ar isotope correlation ages of 542 ± 4 and 338 ± 2 Ma, respectively. These ages are interpreted to date post-amphibolite facies metamorphic cooling. Euhedral zircons from the Point Pleasant orthogneiss, a quartz dioritic gneiss previously interpreted to be the oldest component of the Brookville Gneiss, show slight inheritance and yield 247Pb/206Pb ages ranging from 603 to 631 Ma. The youngest of these is interpreted to be a maximum age for the orthogneiss protolith. These results, together with other recent U-Pb age data, conflict with previous interpretations of the Brookville Gneiss and the metasedimentary Green Head Group with which it is associated, as a mobilized Proterozoic basement-cover succession upon which an Avalonian ensialic arc developed at c. 600-633 Ma. Instead, the age of the orthogneiss matches that of the arc, and the orthogneiss protolith is likely to have been originally intrusive into the Green Head Group. Although the arc succession is unaffected by high-grade metamorphism, the metamorphic cooling age recorded in the "basement" closely follows evidence of within-arc extension at c. 330 Ma. Hence, the arc/"basement" contrasts in tectonothermal regime could be those of varying structural level within the Avalonian arc rather than requiring the proposed existence of entirely separate terranes. RÉSUMÉ De nouvelles données 40Ar/39Ar sur hornblendes et U-Pb sur zircons, issues d'unités considérées jadis comme représentant le socle de la Lanière composite d'Avalon au Nouveau-Brunswick meridional, ont livré des âges de refroidissement métamorphique finiprécambriens ou éocambriens ainsi qu'un âge de protolithe tardipréambrien. Des hornblendes extraites du Gneiss de Brookville ont livré un âge de corrélation isotopique par 40Ar/39Ar de 542 ± 4 Ma; d'autres, provenant d'un bâti amphibolitique intrusif au sein du gneiss, ont livré un âge de 538 ± 2 Ma. On interprète ces âges comme datant le refroidissement métamorphique au-delâ du faciès à amphibolites. Des zircons idiomorphes provenant de l'orthogneiss de Point Pleasant, un gneiss quartzodioritique interprèt auparavant comme le plus ancient constituant du Gneiss de Brookville, montrent un 1éger remaniement et livrent des âges 247Pb/206Pb s'étalant de 603 à 631 Ma. On interprèté le plus jeune de ces âges comme l'âge maximal du protolithe de l'orthogneiss. Ces résultats, tout comme d'autres données U-Pbrecentes, contredisent les interprètations antérieures considéranl le Gneiss de Brookville et le Groupe métasédimentaire de Green Head, auquel il s'associe, comme une succession socle-couverture mobilisée protérozoique sur laquelle un arc sialique avalonien s'est développé il y a en v. 600 à 635 Ma. L'âge de l'orthogneiss correspond plutôt â celui de l'arc et il est probable que le protolithe de l'orthogneiss faisait à l'origine intrusion au sein du Groupe de Green Head. Bien que la succession d'arc n'ait subi aucun métamorphisme de degré é1evé l'âge de refroidissement métamorphique enregistré dans le "socle" Concorde étroitement avec la manifestation d 'une extension intra-arc vers 550 Ma. Par consequent, les contrastes de régime tectonothermique arc/"socle" pourraient reflèter les variations du niveau structural au sein de l'arc avalonien plutôt que necessiter l'existence proposée de lanières tout a fait distinctes. [Traduit par le journal

    An evolutionary stage model of outsourcing and competence destruction : a Triad comparison of the consumer electronics industry

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    Outsourcing has gained much prominence in managerial practice and academic discussions in the last two decades or so. Yet, we still do not understand the full implications of outsourcing strategy for corporate performance. Traditionally outsourcing across borders is explained as a cost-cutting exercise, but more recently the core competency argument states that outsourcing also leads to an increased focus, thereby improving effectiveness. However, no general explanation has so far been provided for how outsourcing could lead to deterioration in a firm‟s competence base. We longitudinally analyze three cases of major consumer electronics manufacturers, Emerson Radio from the U.S., Japan‟s Sony and Philips from the Netherlands to understand the dynamic process related to their sourcing strategies. We develop an evolutionary stage model that relates outsourcing to competence development inside the firm and shows that a vicious cycle may emerge. Thus it is appropriate to look not only at how outsourcing is influenced by an organization‟s current set of competences, but also how it alters that set over time. The four stages of the model are offshore sourcing, phasing out, increasing dependence on foreign suppliers, and finally industry exit or outsourcing reduction. The evolutionary stage model helps managers understand for which activities and under which conditions outsourcing across borders is not a viable option. Results suggest that each of these firms had faced a loss of manufacturing competitiveness in its home country, to which it responded by offshoring and then outsourcing production. When a loss of competences occurred, some outsourcing decisions were reversed

    Cotinine-assessed second-hand smoke exposure and risk of cardiovascular disease in older adults

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    Objectives: To examine whether second-hand smoke (SHS) exposure measured by serum cotinine is associated with increased coronary heart disease (CHD) and stroke risk among contemporary older British adults. Design: Prospective population-based study with self-reported medical history and health behaviours. Fasting blood samples were analysed for serum cotinine and cardiovascular disease (CVD) risk markers. Setting: Primary care centres in 25 British towns in 1998–2001. Patients: 8512 60–79-year-old men and women selected from primary care registers. Main outcome measures: Fatal and non-fatal myocardial infarction (MI; n=445) and stroke (n=386) during median 7.8-year follow-up. Main exposure: Observational study of serum cotinine assayed from fasting blood sample using liquid chromatography tandem mass spectrometry method, and self-reported smoking history. Results: Among 5374 non-smokers without pre-existing CVD, geometric mean cotinine was 0.15 ng/ml (IQR 0.05–0.30). Compared with non-smokers with cotinine ≤0.05 ng/ml, higher cotinine levels (0.06–0.19, 0.2–0.7 and 0.71–15.0 ng/ml) showed little association with MI; adjusted HRs were 0.92 (95% CI 0.63 to 1.35), 1.07 (0.73 to 1.55) and 1.09 (0.69 to 1.72), p(trend)=0.69. Equivalent HRs for stroke were 0.82 (0.55 to 1.23), 0.74 (0.48 to 1.13) and 0.69 (0.41 to 1.17), p(trend)=0.065. The adjustment for sociodemographic, behavioural and CVD risk factors had little effect on the results. The HR of MI for smokers (1–9 cigarettes/day) compared with non-smokers with cotinine ≤0.05 ng/ml was 2.14 (1.39 to 3.52) and 1.03 (0.52 to 2.04) for stroke. Conclusions: In contemporary older men and women, SHS exposure (predominantly at low levels) was not related to CHD or stroke risks, but we cannot rule out the possibility of modest effects at higher exposure levels

    Prognosis for long-term survival and renal recovery in critically ill patients with severe acute renal failure: a population-based study

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    INTRODUCTION: Severe acute renal failure (sARF) is associated with considerable morbidity, mortality and use of healthcare resources; however, its precise epidemiology and long-term outcomes have not been well described in a non-specified population. METHODS: Population-based surveillance was conducted among all adult residents of the Calgary Health Region (population 1 million) admitted to multidisciplinary and cardiovascular surgical intensive care units between May 1 1999 and April 30 2002. Clinical records were reviewed and outcome at 1 year was assessed. RESULTS: sARF occurred in 240 patients (11.0 per 100,000 population/year). Rates were highest in males and older patients (≥65 years of age). Risk factors for development of sARF included previous heart disease, stroke, pulmonary disease, diabetes mellitus, cancer, connective tissue disease, chronic renal dysfunction, and alcoholism. The annual mortality rate was 7.3 per 100,000 population with rates highest in males and those ≥65 years. The 28-day, 90-day, and 1-year case-fatality rates were 51%, 60%, and 64%, respectively. Increased Charlson co-morbidity index, presence of liver disease, higher APACHE II score, septic shock, and need for continuous renal replacement therapy were independently associated with death at 1 year. Renal recovery occurred in 78% (68/87) of survivors at 1 year. CONCLUSION: sARF is common and males, older patients, and those with underlying medical conditions are at greatest risk. Although the majority of patients with sARF will die, most survivors will become independent from renal replacement therapy within a year

    The synergistic integration of computational fluid dynamics and experimental fluid dynamics for ground effect aerodynamics studies

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    This article highlights the ‘synergistic’ use of experimental fluid dynamics (EFD) and computational fluid dynamics (CFD), where the two sets of simulations are performed concurrently and by the same researcher. In particular, examples from the area of ground effect aerodynamics are discussed, where the major facility used was also designed through a combination of CFD and EFD. Three examples are than outlined, to demonstrate the insight that can be obtained from the integration of CFD and EFD studies. The case studies are the study of dimple flow (to enhance aerodynamic performance), the analysis of a Formula-style front wing and wheel, and the study of compressible flow ground effect aerodynamics. In many instances, CFD has been used to not only provide complementary information to an experimental study, but to design the experiments. Laser-based, non-intrusive experimental techniques were used to provide an excellent complement to CFD. The large datasets found from both experimental and numerical simulations have required a new methodology to correlate the information; a new post-processing method has been developed, making use of the kriging and co-kriging estimators, to develop correlations between the often disparate data types

    Taming the snake in paradise: combining institutional design and leadership to enhance collaborative innovation

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    The growing expectations to public services and the pervasiveness of wicked problems in times characterized by growing fiscal constraints call for the enhancement of public innovation, and new research suggests that multi-actor collaboration in networks and partnerships is superior to hierarchical and market-based strategies when it comes to spurring such innovation. Collaborative innovation seems ideal as it builds on diversity to generate innovative public value outcomes, but there is a catch since diversity may clash with the need for constructing a common ground that allows participating actors to agree on a joint and innovative solution. The challenge for collaborative innovation – taming the snake in paradise – is to nurture the diversity of views, ideas and forms of knowledge while still establishing a common ground for joint learning. While we know a great deal about the dynamics of the mutually supportive processes of collaboration, learning and innovation, we have yet to understand the role of institutional design and leadership in spurring collaborative innovation and dealing with this tension. Building on extant research, the article draws suitable cases from the Collaborative Governance Data Bank and uses Qualitative Comparative Analysis to explore how multiple constellations of institutional design and leadership spur collaborative innovation. The main finding is that, even though certain institutional design features reduce the need for certain leadership roles, the exercise of hands-on leadership is more important for securing collaborative innovation outcomes than hands-off institutional design

    Determinants of response to a parent questionnaire about development and behaviour in 3 year olds: European multicentre study of congenital toxoplasmosis.

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    Background: We aimed to determine how response to a parent-completed postal questionnaire measuring development, behaviour, impairment, and parental concerns and anxiety, varies in different European centres. Methods: Prospective cohort study of 3 year old children, with and without congenital toxoplasmosis, who were identified by prenatal or neonatal screening for toxoplasmosis in 11 centres in 7 countries. Parents were mailed a questionnaire that comprised all or part of existing validated tools. We determined the effect of characteristics of the centre and child on response, age at questionnaire completion, and response to child drawing tasks. Results: The questionnaire took 21 minutes to complete on average. 67% (714/1058) of parents responded. Few parents (60/1058) refused to participate. The strongest determinants of response were the score for organisational attributes of the study centre (such as direct involvement in follow up and access to an address register), and infection with congenital toxoplasmosis. Age at completion was associated with study centre, presence of neurological abnormalities in early infancy, and duration of prenatal treatment. Completion rates for individual questions exceeded 92% except for child completed drawings of a man (70%), which were completed more by girls, older children, and in certain centres. Conclusion: Differences in response across European centres were predominantly related to the organisation of follow up and access to correct addresses. The questionnaire was acceptable in all six countries and offers a low cost tool for assessing development, behaviour, and parental concerns and anxiety, in multinational studies

    Oligodendroglia Are Particularly Vulnerable to Oxidative Damage After Neurotrauma In Vivo.

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    In the paper "Oligodendroglia are particularly vulnerable to oxidative damage after neurotrauma in vivo," we determined the extent of oxidative damage to specific cellular subpopulations and structures within regions vulnerable to secondary degeneration and assessed the effect this had on oligodendroglial function. Comparative assessment of oxidative damage demonstrated selective vulnerability of oligodendroglia, specifically oligodendrocyte progenitor cells (OPCs) to DNA oxidation in vivo. Immunohistochemical fate mapping along the oligodendroglial lineage showed a transient susceptibility of these cells to DNA oxidation, protein nitration, and lipid peroxidation, with mature oligodendrocytes derived immediately after injury more vulnerable to DNA oxidation than their counterparts existing at the time of injury or later derived. In situ hybridization demonstrated a reduction in myelin regulatory factor (MyRF) messenger RNA (mRNA) fluorescence in newly derived mature oligodendrocytes, suggesting a compromise in the production and maintenance of the myelin sheath in these cells. The data imply a deficit in the normal differentiation of OPCs to myelinating oligodendrocytes, associated with a transient increase in oxidative damage, which may contribute to the dysmyelinating phenotype seen at chronic time points after injury. Identifying and understanding the sources of this oxidative damage is integral for the development of therapeutic interventions for neurotrauma
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