47 research outputs found

    Analysis of brittle Paleogene structures in the Svea region, eastern Spitsbergen, Svalbard

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    During the Paleogene rifting of Svalbard and Greenland along a dextral transform, deformation occurred in two stages. Initial transpression, which formed a fold-and-thrust belt in western Spitsbergen and a foreland basin in central Spitsbergen, was followed by transtensional rifting. Small-scale brittle structures are observed in the subhorizontal Paleogene strata on the foreland basinā€™s eastern edge. This study analyzes the orientations and paleostress regimes of these structures in order to determine their tectonic origins. Orientation data from faults, joints, and slickenlines were collected within the Svea Nord mine and the surrounding area in order to resolve the paleostress regimes of these structures. An analysis of lineament orientations from aerial imagery was conducted to solidify these initial findings, based on the assumption that these linear erosional features are related to pre-existing bedrock fractures. Results show two populations of faults: NNW-SSE striking, west-dipping thrust faults and ENE-WSW striking normal faults. Joint orientation measurements reveal two dominant subvertical joint set orientations: ENE-WSW and NNW-SSE. The lineament data show a major NE-SW trend, and a minor NW-SE trend. Paleostress orientations of these structures suggest ENE-directed compression and NNW-SSE extension for the thrust faults and normal faults respectively. Both the joints and lineaments indicate a strike-slip setting. Given the age constraints on the faults and fractures, their orientations and paleostress determinations, they can be correlated with previously documented structures associated with fold-and-thrust belt deformation. That these small-scale extensional structures are likely related to the fold-and-thrust belt suggests that they formed in response to the larger dextral transpressive tectonic setting

    Unveiling Extragalactic Star Formation Using Radio Recombination Lines: An Expanded Very Large Array Pilot Study With Ngc 253

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    Radio recombination lines (RRLs) are powerful, extinction-free diagnostics of the ionized gas in young, star-forming regions. Unfortunately, these lines are difficult to detect in external galaxies. We present the results of Expanded Very Large Array (EVLA) observations of the RRL and radio continuum emission at 33 GHz from NGC 253, a nearby nuclear starburst galaxy. We detect the previously unobserved H58{alpha} and H59{alpha} RRLs and make simultaneous sensitive measurements of the continuum. We measure integrated line fluxes of 44.3 {+-} 0.7 W m{sup -2} and 39.9 {+-} 0.8 W m{sup -2} for the H58{alpha} and H59{alpha} lines, respectively. The thermal gas in NGC 253 is kinematically complex with multiple velocity components. We constrain the density of the thermal gas to (1.4-4) x 10{sup 4} cm{sup -3} and estimate an ionizing photon flux of 1 x 10{sup 53} s{sup -1}. We use the RRL kinematics and the derived ionizing photon flux to show that the nuclear region of NGC 253 is not gravitationally bound, which is consistent with the outflow of gas inferred from the X-ray and H{alpha} measurements. The line profiles, fluxes, and kinematics of the H58{alpha} and H59{alpha} lines agree with those of RRLs at different frequencies confirming themore Ā» accuracy of the previous, more difficult, high-frequency observations. We find that the EVLA is an order of magnitude more efficient for extragalactic RRL observations than the Very Large Array. These observations demonstrate both the power of the EVLA and the future potential of extragalactic RRL studies with the EVLA.Ā« les

    Unveiling Extragalactic Star Formation Using Radio Recombination Lines: An EVLA Pilot Study with NGC 253

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    Radio recombination lines (RRLs) are powerful, extinction-free diagnostics of the ionized gas in young, star-forming regions. Unfortunately, these lines are difficult to detect in external galaxies. We present the results of EVLA observations of the RRL and radio continuum emission at 33 GHz from NGC 253, a nearby nuclear starburst galaxy. We detect the previously unobserved H58a and H59a RRLs and make simultaneous sensitive measurements of the continuum. We measure integrated line fluxes of 44.3Ā±0.744.3 \pm 0.7 W māˆ’2^{-2} and 39.9Ā±0.839.9 \pm 0.8 W māˆ’2^{-2} for the H58a and H59a lines, respectively. The thermal gas in NGC 253 is kinematically complex with multiple velocity components. We constrain the density of the thermal gas to 1.4āˆ’4Ɨ1041.4 - 4 \times 10^4 cmāˆ’3^{-3} and estimate an ionizing photon flux of 1Ɨ10531 \times 10^{53} sāˆ’1^{-1}. We use the RRL kinematics and the derived ionizing photon flux to show that the nuclear region of NGC 253 is not gravitationally bound, which is consistent with the outflow of gas inferred from the X-ray and Halpha measurements. The line profiles, fluxes, and kinematics of the H58a and H59a lines agree with those of RRLs at different frequencies confirming the accuracy of the previous, more difficult, high frequency observations. We find that the EVLA is an order of magnitude more efficient for extragalactic RRL observations than the VLA. These observations demonstrate both the power of the EVLA and the future potential of extragalactic RRL studies with the EVLA.Comment: Accepted for publication in the ApJL EVLA Special Issue. Version with high resolution figures at http://www.astro.virginia.edu/~aak8t/data/rrl/ms.p

    Neonatal hyperoxic lung injury favorably alters adult right ventricular remodeling response to chronic hypoxia exposure

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    The development of pulmonary hypertension (PH) requires multiple pulmonary vascular insults, yet the role of early oxygen therapy as an initial pulmonary vascular insult remains poorly defined. Here, we employ a two-hit model of PH, utilizing postnatal hyperoxia followed by adult hypoxia exposure, to evaluate the role of early hyperoxic lung injury in the development of later PH. Sprague-Dawley pups were exposed to 90% oxygen during postnatal days 0-4 or 0-10 or to room air. All pups were then allowed to mature in room air. At 10 wk of age, a subset of rats from each group was exposed to 2 wk of hypoxia (Patm = 362 mmHg). Physiological, structural, and biochemical endpoints were assessed at 12 wk. Prolonged (10 days) postnatal hyperoxia was independently associated with elevated right ventricular (RV) systolic pressure, which worsened after hypoxia exposure later in life. These findings were only partially explained by decreases in lung microvascular density. Surprisingly, postnatal hyperoxia resulted in robust RV hypertrophy and more preserved RV function and exercise capacity following adult hypoxia compared with nonhyperoxic rats. Biochemically, RVs from animals exposed to postnatal hyperoxia and adult hypoxia demonstrated increased capillarization and a switch to a fetal gene pattern, suggesting an RV more adept to handle adult hypoxia following postnatal hyperoxia exposure. We concluded that, despite negative impacts on pulmonary artery pressures, postnatal hyperoxia exposure may render a more adaptive RV phenotype to tolerate late pulmonary vascular insults

    The Massive Star Content of NGC 3603

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    We investigate the massive star content of NGC 3603, the closest known giant H II region. We have obtained spectra of 26 stars in the central cluster using the Baade 6.5-m telescope (Magellan I). Of these 26 stars, 16 had no previous spectroscopy. We also obtained photometry of all of the stars with previous or new spectroscopy, primarily using archival HST ACS/HRC images. We use these data to derive an improved distance to the cluster, and to construct an H-R diagram for discussing the masses and ages of the massive star content of this cluster.Comment: Accepted by the Astronomical Journal. This revision updates the coordinates in Table 1 by (-0.18sec, +0.2") to place them on the UCAC2 syste

    Long-Term Toxicity and Health-Related Quality of Life After Adjuvant Chemoradiation Therapy or Radiation Therapy Alone for High-Risk Endometrial Cancer in the Randomized PORTEC-3 Trial

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    PURPOSE: The survival results of the PORTEC-3 trial showed a significant improvement in both overall and failure-free survival with chemoradiation therapy versus pelvic radiation therapy alone. The present analysis was performed to compare long-term adverse events (AE) and health-related quality of life (HRQOL). METHODS AND MATERIALS: In the study, 660 women with high-risk endometrial cancer were randomly assigned to receive chemoradiation therapy (2 concurrent cycles of cisplatin followed by 4 cycles of carboplatin/paclitaxel) or radiation therapy alone. Toxicity was graded using Common Terminology Criteria for Adverse Events, version 3.0. HRQOL was measured using EORTC QLQ-C30 and CX24/OV28 subscales and compared with normative data. An as-treated analysis was performed. RESULTS: Median follow-up was 74.6 months; 574 (87%) patients were evaluable for HRQOL. At 5 years, grade ā‰„2 AE were scored for 78 (38%) patients who had received chemoradiation therapy versus 46 (24%) who had received radiation therapy alone (P = .008). Grade 3 AE did not differ significantly between the groups (8% vs 5%, P = .18) at 5 years, and only one new late grade 4 toxicity had been reported. At 3 and 5 years, sensory neuropathy toxicity grade ā‰„2 persisted after chemoradiation therapy in 6% (vs 0% after radiation therapy, P < .001) and more patients reported significant tingling or numbness at HRQOL (27% vs 8%, P < .001 at 3 years; 24% vs 9%, P = .002 at 5 years). Up to 3 years, more patients who had chemoradiation therapy reported limb weakness (21% vs 5%, P < .001) and lower physical (79 vs 87, P < .001) and role functioning (78 vs 88, P < .001) scores. Both treatment groups reported similar long-term global health/quality of life scores, which were better than those of the normative population. CONCLUSIONS: This study shows a long-lasting, clinically relevant, negative impact of chemoradiation therapy on toxicity and HRQOL, most importantly persistent peripheral sensory neuropathy. Physical and role functioning impairments were seen until 3 years. These long-term data are essential for patient information and shared decision-making regarding adjuvant chemotherapy for high-risk endometrial cancer

    Health, education, and social care provision after diagnosis of childhood visual disability

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    Aim: To investigate the health, education, and social care provision for children newly diagnosed with visual disability.Method: This was a national prospective study, the British Childhood Visual Impairment and Blindness Study 2 (BCVIS2), ascertaining new diagnoses of visual impairment or severe visual impairment and blindness (SVIBL), or equivalent vi-sion. Data collection was performed by managing clinicians up to 1-year follow-up, and included health and developmental needs, and health, education, and social care provision.Results: BCVIS2 identified 784 children newly diagnosed with visual impairment/SVIBL (313 with visual impairment, 471 with SVIBL). Most children had associated systemic disorders (559 [71%], 167 [54%] with visual impairment, and 392 [84%] with SVIBL). Care from multidisciplinary teams was provided for 549 children (70%). Two-thirds (515) had not received an Education, Health, and Care Plan (EHCP). Fewer children with visual impairment had seen a specialist teacher (SVIBL 35%, visual impairment 28%, Ļ‡2p < 0.001), or had an EHCP (11% vs 7%, Ļ‡2p < 0 . 01).Interpretation: Families need additional support from managing clinicians to access recommended complex interventions such as the use of multidisciplinary teams and educational support. This need is pressing, as the population of children with visual impairment/SVIBL is expected to grow in size and complexity.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

    Can We Do It? Developing Students\u27 Identities as Readers and Writers in Today\u27s High-Stakes Classrooms

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    In spite of high-stakes testing that challenges teachers to think about classroom decisions, the authors believe teachers can promote classroom practices that provide opportunities to develop the reading and writing identities of their students while also preparing students for required assessments. Using teacher writing as mentor text, showing students how to play with language in a variety of ways, and modeling reading and writing for authentic purposes by using their own reading and writing life as an example, teachers can help students develop literacy skills and flourish as readers and writers
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