117 research outputs found

    Protracted shearing at mid‐crustal conditions during large‐scale thrusting in the Scandinavian Caledonides

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    During continental collision, large tracts of crust are mobilised along major shear zones. The metamorphic conditions at which these zones operate, the duration of thrusting, and the deformation processes that facilitated hundreds of km of tectonic transport are still unclear. In the Scandinavian Caledonides, the Lower Seve Nappe displays a main mylonitic foliation with thickness of ~1 km. This foliation is overprinted by a brittle‐to‐ductile deformation pattern localized in C and C’‐type shear bands proximal to the tectonic contact with the underlying SĂ€rv Nappe. Thermobarometry of amphibolites and micaschists suggest a first high‐pressure stage at 400‐500°C and 1‐1.3 GPa recorded in mineral relics. The main mylonitic foliation developed under epidote amphibolite facies conditions along the retrograde path from 600°C and 1 GPa to 500°C and 0.5 GPa. Age dating of synkinematic titanite grains in the amphibolites indicates that this mylonitic fabric formed at around 417 ± 9 Ma, but older ages spanning 460‐430 Ma could represent earlier stages of mylonitization. The shear bands developed at lower metamorphic conditions of 300‐400°C and ~0.3 GPa. In the micaschists, the recrystallized grain size of quartz decreases towards the shear bands. Monomineralic quartz layers are eventually dismembered to form polyphase aggregates deforming by dominant grain size sensitive creep accompanied by slip in muscovite and chlorite. Plagioclase zoning truncations suggest that the shear bands originated by fracturing followed by ductile deformation. The results suggest protracted and long‐lasting shearing under amphibolite to greenschist facies conditions during the juxtaposition, stacking and exhumation of the Lower Seve Nappe

    Body mass index is not a predictor of biochemical recurrence after radical prostatectomy in Dutch men diagnosed with prostate cancer

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    Contains fulltext : 95677.pdf (publisher's version ) (Closed access)PURPOSE: To determine the effect of body mass index (BMI) on clinical and pathological characteristics at time of diagnosis and on risk of biochemical recurrence after radical prostatectomy among Dutch men diagnosed with prostate cancer. METHODS: In total, 1,116 prostate cancer patients with known BMI, diagnosed between 2003 and 2006, were identified from the population-based cancer registry held by the Comprehensive Cancer Centre East, The Netherlands. Of these, 504 patients underwent a radical prostatectomy. Patients were categorized as normal weight (BMI /= 30 kg/m(2)). Multivariable proportional hazards regression models, adjusted for age, prediagnostic PSA levels, and pathological characteristics were used to evaluate BMI as a prognostic factor for biochemical recurrence after radical prostatectomy. RESULTS: Overall, clinical and biopsy characteristics did not significantly differ among BMI groups. Pathological characteristics after radical prostatectomy did not significantly differ among BMI groups, except for tumor stage, which was highest in obese patients (P = 0.017). For patients treated with radical prostatectomy, 5-year risk (95% Confidence Intervals) of biochemical recurrence was 30% (23-37%) for normal weight, 32% (25-39%) for overweight, and 25% (9-41%) for obese patients (log rank P = 0.810). BMI was not an independent prognostic factor for biochemical recurrence in multivariable proportional hazards regression analyses (HR 0.99 per kg/m(2), 95% CI: 0.93-1.06). CONCLUSIONS: Compared with non-obese men, pathological tumor stage tended to be higher in obese men. Clinical relevance of this finding is unclear, because BMI was not an independent predictor of biochemical recurrence after radical prostatectomy

    Validation of Claims Data for Absorbing Pads as a Measure for Urinary Incontinence after Radical Prostatectomy, a National Cross-Sectional Analysis

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    The use of healthcare insurance claims data for urinary incontinence (UI) pads has the potential to serve as an objective measure for assessing post-radical prostatectomy UI rates, but its validity for this purpose has not been established. The aim of this study is to correlate claims data with Patient Reported Outcome Measures (PROMs) for UI pad use. Patients who underwent RP in the Netherlands between September 2019 and February 2020 were included. Incontinence was defined as the daily use of ≄1 pad(s). Claims data for UI pads at 12-15 months after RP were extracted from a nationwide healthcare insurance database in the Netherlands. Participating hospitals provided PROMS data. In total, 1624 patients underwent RP. Corresponding data of 845 patients was provided by nine participating hospitals, of which 416 patients were matched with complete PROMs data. Claims data and PROMs showed 31% and 45% post-RP UI (≄1 pads). UI according to claims data compared with PROMs had a sensitivity of 62%, specificity of 96%, PPV of 92%, NPV of 75% and accuracy of 81%. The agreement between both methods was moderate (Îș = 0.60). Claims data for pads moderately align with PROMs in assessing post-prostatectomy urinary incontinence and could be considered as a conservative quality indicator.</p

    Teachers' ideas versus experts' descriptions of 'the good teacher' in postgraduate medical education: implications for implementation. A qualitative study

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    Contains fulltext : 96394.pdf (publisher's version ) (Open Access)BACKGROUND: When innovations are introduced in medical education, teachers often have to adapt to a new concept of what being a good teacher includes. These new concepts do not necessarily match medical teachers' own, often strong beliefs about what it means to be a good teacher.Recently, a new competency-based description of the good teacher was developed and introduced in all the Departments of Postgraduate Medical Education for Family Physicians in the Netherlands. We compared the views reflected in the new description with the views of teachers who were required to adopt the new framework. METHODS: Qualitative study. We interviewed teachers in two Departments of Postgraduate Medical Education for Family Physicians in the Netherlands. The transcripts of the interviews were analysed independently by two researchers, who coded and categorised relevant fragments until consensus was reached on six themes. We investigated to what extent these themes matched the new description. RESULTS: Comparing the teachers' views with the concepts described in the new competency-based framework is like looking into two mirrors that reflect clearly dissimilar images. At least two of the themes we found are important in relation to the implementation of new educational methods: the teachers' identification and organisational culture. The latter plays an important role in the development of teachers' ideas about good teaching. CONCLUSIONS: The main finding of this study is the key role played by the teachers' feelings regarding their professional identity and by the local teaching culture in shaping teachers' views and expectations regarding their work. This suggests that in implementing a new teaching framework and in faculty development programmes, careful attention should be paid to teachers' existing identification model and the culture that fostered it

    Oxygen dependence of metabolic fluxes and energy generation of Saccharomyces cerevisiae CEN.PK113-1A

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    <p>Abstract</p> <p>Background</p> <p>The yeast <it>Saccharomyces cerevisiae </it>is able to adjust to external oxygen availability by utilizing both respirative and fermentative metabolic modes. Adjusting the metabolic mode involves alteration of the intracellular metabolic fluxes that are determined by the cell's multilevel regulatory network. Oxygen is a major determinant of the physiology of <it>S. cerevisiae </it>but understanding of the oxygen dependence of intracellular flux distributions is still scarce.</p> <p>Results</p> <p>Metabolic flux distributions of <it>S. cerevisiae </it>CEN.PK113-1A growing in glucose-limited chemostat cultures at a dilution rate of 0.1 h<sup>-1 </sup>with 20.9%, 2.8%, 1.0%, 0.5% or 0.0% O<sub>2 </sub>in the inlet gas were quantified by <sup>13</sup>C-MFA. Metabolic flux ratios from fractional [U-<sup>13</sup>C]glucose labelling experiments were used to solve the underdetermined MFA system of central carbon metabolism of <it>S. cerevisiae</it>.</p> <p>While ethanol production was observed already in 2.8% oxygen, only minor differences in the flux distribution were observed, compared to fully aerobic conditions. However, in 1.0% and 0.5% oxygen the respiratory rate was severely restricted, resulting in progressively reduced fluxes through the TCA cycle and the direction of major fluxes to the fermentative pathway. A redistribution of fluxes was observed in all branching points of central carbon metabolism. Yet only when oxygen provision was reduced to 0.5%, was the biomass yield exceeded by the yields of ethanol and CO<sub>2</sub>. Respirative ATP generation provided 59% of the ATP demand in fully aerobic conditions and still a substantial 25% in 0.5% oxygenation. An extensive redistribution of fluxes was observed in anaerobic conditions compared to all the aerobic conditions. Positive correlation between the transcriptional levels of metabolic enzymes and the corresponding fluxes in the different oxygenation conditions was found only in the respirative pathway.</p> <p>Conclusion</p> <p><sup>13</sup>C-constrained MFA enabled quantitative determination of intracellular fluxes in conditions of different redox challenges without including redox cofactors in metabolite mass balances. A redistribution of fluxes was observed not only for respirative, respiro-fermentative and fermentative metabolisms, but also for cells grown with 2.8%, 1.0% and 0.5% oxygen. Although the cellular metabolism was respiro-fermentative in each of these low oxygen conditions, the actual amount of oxygen available resulted in different contributions through respirative and fermentative pathways.</p

    The Friningen Garnet Peridotite (central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite

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    We present pseudosections of Cr-bearing garnet peridotite that together with new mineral-chemical data allow quantification of the early PT conditions of the original lithospheric mantle assemblage (M1) of the Friningen Garnet Peridotite (FGP) located in the central/middle belt of the Seve Nappe Complex in central Sweden. Results indicate that the early, coarse grained, olivine. +. orthopyroxene. +. clinopyroxene. +. "high Cr" garnet assemblage (M1a) was formed at 1100. ±. 100. °C and 5.0. ±. 0.5. GPa. These metamorphic conditions were followed by an inferred late Proterozoic exhumation event down to 850-900. °C and 1.5. GPa (M1b). The latter PT estimate is based on the breakdown of high-Cr M1a garnet (Cr#. =. 0.065). +. olivine into an orthopyroxene. +. clinopyroxene. +. spinel (Cr#. =. 0.15-0.25). ±. pargasite kelyphite (M1b) and the exsolution of garnet from Al-rich orthopyroxene and clinopyroxene. The M1b kelyphite is overprinted by an early-Caledonian UHPM mineral assemblage (M2; T. =. 800. °C and P. =. 3.0. GPa), equivalent to the earlier discovered UHP assemblage within an eclogitic dyke that cross-cuts FGP. In the garnet peridotite M2 is displayed by low-Cr garnet (Cr#. =. 0.030) growing together with spinel (Cr#. =. 0.35-0.45), both these minerals form part of the olivine. +. orthopyroxene. +. clinopyroxene. +. garnet. +. spinel. +. pargasite M2 assemblage. The formation of plagioclase. +. diopside symplectites after omphacite and breakdown of kyanite to sapphirine. +. albite in internal eclogite and the breakdown of M2 olivine. +. garnet to amphibole. +. orthopyroxene. +. spinel assemblages (M3) in garnet peridotite indicate post-UHP isothermal decompression down to 750-800. °C and 0.8-1.0. GPa (=. M3). Multiphase solid-and fluid inclusion assemblages composed of Sr-bearing magnesite, dolomite or carbon decorate linear defect structures within M1a-b minerals and/or form subordinate local assemblages together with M2 minerals. The latter are interpreted as evidence for infiltration of early-Caledonian COH-bearing subduction zone fluids. The well-defined PTt-deformation path of the FGP resembles that of a mantle wedge garnet peridotite. The M1 assemblage originates from the base of a cold, old and thick subcontinental lithospheric mantle that is inferred to extend asymmetrically leading to extreme exhumation of FGP down to lithospheric conditions around 1.5. GPa and 850-900. °C. After that the FGP became incorporated into the subducting continental crust of the SNC during "early-Caledonian" subduction (M2) down to UHPM conditions (800. °C/3.0. GPa), subsequently followed by eduction back to sub-crustal levels. As such, FGP is the first locality in the Swedish Caledonides from which two UHP metamorphic events are described, the first event can be related to the formation of an ancient (>. 1.0. Ga) lithosphere underneath a craton (Rodinia) and the second is of early-Caledonian age

    Fragments of deeper parts of the hanging wall mantle preserved as orogenic peridotites in the central belt of the Seve Nappe Complex, Sweden

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    Formation conditions of olivine microstructures are investigated in the KittelfjĂ€ll spinel peridotite (KSP), a fragment of lithospheric mantle which occurs as an isolated body within high grade metamorphic crustal rocks of the Seve Nappe Complex (SNC), southern VĂ€sterbotten, central Sweden. The KSP is an orogenic peridotite containing a well developed penetrative compositional layering, defined by highly depleted dunite with olivine Mg# (100 × Mg/Mg + Fe) of 92.0-93.5 and harzburgite with lower Mg# (91.0-92.5). Dunite is characterized by three contrasting olivine microstructures formed in response to different tectonometamorphic events: Coarse-grained, highly strained olivine porphyroclasts (M1) up to 20. cm long are surrounded by dynamically recrystallized olivine grains (M2) defining a characteristic olivine "foam" microstructure (grain size: 200-2000. ÎŒm). An olivine "mortar" (M3) microstructure (10-50. ÎŒm) forms a penetrative fabric element only in strongly localized, cm-to-m sized shear zones that crosscut earlier structures/foliations. Olivine fabric analysis in synergy, with mineralogical and chemical analyses, reveals that the KSP body represents old, possibly Archean, sub-continental lithospheric mantle that was crustally emplaced into the Caledonian tectonic edifice from the hanging wall mantle during exhumation of the subducted Seve Nappe Complex (JĂ€mtlandian orogeny. ~. 454. Ma). Olivine porphyroclasts (M1) grew at high temperature during dominant isobaric cooling after extensive polybaric melt extraction (> 40%) and subsequent refertilization. The onset of the early Caledonian deformation is interpreted to be related to the crustal emplacement of the KSP during eduction of the SNC. This phase is characterized by the development of the olivine M2 foam microstructure, formed at 650-830. °C/1-2. GPa by dislocation creep processes producing an E-type CPO's by the operation of the [100](001) and subordinate [001](100) slip systems with operating flow stress levels around 8-48. MPa. In contrast the M3 olivine "mortar" microstructure formed at 550-600. °C/0.45-0.6. GPa and represents deformation after the subducted slab had returned to shallow crustal levels. It is proposed here that the presence of a penetrative olivine M2 "foam" microstructure can be used as an easy tool in the field to discriminate between mantle wedge (i.e. sub-continental affinity), ophiolite (i.e. sub-oceanic affinity), and/or hyper-extensional peridotite in the Scandinavian Caledonides. The latter two peridotite subtypes may have similar M2 microstructures, but exclusively restricted to the structural base of the bodies. Alternatively in basal parts of ophiolites, M3 microstructures directly overprint coarser grained proto-granular olivine microstructures. © 2014 Elsevier B.V
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