62 research outputs found

    Measurements of Gamow-Teller Strength Distributions in Masses 13 and 15

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Spin Transfer Measurements for (p,n) Reactions at Intermediate Energy

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – I. Results from a seismic refraction profile

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    Author Posting. © Blackwell, 2006. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 167 (2006): 127-156, doi:10.1111/j.1365-246X.2006.02988.x.A P-wave velocity model along a 565-km-long profile across the Grand Banks/Newfoundland basin rifted margin is presented. Continental crust ~36-kmthick beneath the Grand Banks is divided into upper (5.8-6.25 km/s), middle (6.3- 6.53 km/s) and lower crust (6.77-6.9 km/s), consistent with velocity structure of Avalon zone Appalachian crust. Syn-rift sediment sequences 6-7-km thick occur in two primary layers within the Jeanne d’Arc and the Carson basins (~3 km/s in upper layer; ~5 km/s in lower layer). Abrupt crustal thinning (Moho dip ~ 35º) beneath the Carson basin and more gradual thinning seaward forms a 170-km-wide zone of rifted continental crust. Within this zone, lower and middle continental crust thin preferentially seaward until they are completely removed, while very thin (<3 km) upper crust continues ~60 km farther seaward. Adjacent to the continental crust, high velocity gradients (0.5-1.5 s-1) define an 80-km-wide zone of transitional basement that can be interpreted as exhumed, serpentinized mantle or anomalously thin oceanic crust, based on its velocity model alone. We prefer the exhumed-mantle interpretation after considering the non-reflective character of the basement and the low amplitude of associated magnetic anomalies, which are atypical of oceanic crust. Beneath both the transitional basement and thin (<6 km) continental crust, a 200-kmwide zone with reduced mantle velocities (7.6-7.9 km/s) is observed, which is interpreted as partially (<10%) serpentinized mantle. Seaward of the transitional basement, 2- to 6-km-thick crust with layer 2 (4.5-6.3 km/s) and layer 3 (6.3-7.2 km/s) velocities is interpreted as oceanic crust. Comparison of our crustal model with profile IAM-9 across the Iberia Abyssal Plain on the conjugate Iberia margin suggests asymmetrical continental breakup in which a wider zone of extended continental crust has been left on the Newfoundland side.This research was supported by National Science Foundation (NSF) grants OCE-9819053 and OCE-0326714, by the National Sciences and Engineering Research Council of Canada (NSERC), and by the Danish National Research Foundation. B. Tucholke also acknowledges support from the Henry Bryant Bigelow Chair in Oceanography from Woods Hole Oceanographic Institution

    Seismic investigations of the O'Higgins Seamount Group and Juan Fernández Ridge: aseismic ridge emplacement and lithosphere hydration

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    The O'Higgins Seamount Group is a cluster of volcanic domes located 120 km west of the central Chilean Trench on the crest of the Juan Fernández Ridge. This aseismic hot spot track is subducting under South America triggering a belt of intraslab earthquake hypocenters extending about 700 km inland. The Juan Fernández Ridge marks the southern boundary of a shallow subduction segment. Subduction of oceanic basement relief has been suggested as a cause for the “flat” slab segments characterizing the Andean trench system. The Juan Fernández Ridge, however, shows only moderate crustal thickening, inadequate to cause significant buoyancy. In 2001, wide-angle seismic data were collected along two perpendicular profiles crossing the O'Higgins Group. We present tomographic images of the volcanic edifices and adjacent outer rise-trench environment, which indicate a magmatic origin of the seamounts dominated by extrusive processes. High-resolution bathymetric data yield a detailed image of a network of syngenetic structures reactivated in the outer rise setting. A pervasive fault pattern restricted to the hot spot modified lithosphere coincides with anomalous low upper mantle velocities gained from a tomographic inversion of seismic mantle phases. Reduced uppermost mantle velocities are solely found underneath the Juan Fernández Ridge and may indicate mineral alterations. Enhanced buoyancy due to crustal and upper mantle hydration may contribute an additional mechanism for shallow subduction, which prevails to the north after the southward migration of the Juan Fernández Ridge

    Adverse Drug Reactions in Children—A Systematic Review

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    Adverse drug reactions in children are an important public health problem. We have undertaken a systematic review of observational studies in children in three settings: causing admission to hospital, occurring during hospital stay and occurring in the community. We were particularly interested in understanding how ADRs might be better detected, assessed and avoided

    Temporizing management vs immediate delivery in early-onset severe preeclampsia between 28 and 34 weeks of gestation (TOTEM study): An open-label randomized controlled trial

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    Introduction: There is little evidence to guide the timing of delivery of women with early-onset severe preeclampsia. We hypothesize that immediate delivery is not inferior for neonatal outcome but reduces maternal complications compared with temporizing management. Material and methods: This Dutch multicenter open-label randomized clinical trial investigated non-inferiority for neonatal outcome of temporizing management as compared with immediate delivery (TOTEM NTR 2986) in women between 27+5 and 33+5 weeks of gestation admitted for early-onset severe preeclampsia with or without HELLP syndrome. In participants allocated to receive immediate delivery, either induction of labor or cesarean section was initiated at least 48 hours after admission. Primary outcomes were adverse perinatal outcome, defined as a composite of severe respiratory distress syndrome, bronchopulmonary dysplasia, culture proven sepsis, intraventricular hemorrhage grade 3 or worse, periventricular leukomalacia grade 2 or worse, necrotizing enterocolitis stage 2 or worse, and perinatal death. Major maternal complications were secondary outcomes. It was estimated 1130 women needed to be enrolled. Analysis was by intention-to-treat. Results: The trial was halted after 35 months because of slow recruitment. Between February 2011 and December 2013, a total of 56 women were randomized to immediate delivery (n = 26) or temporizing management (n = 30). Median gestational age at randomization was 30 weeks. Median prolongation of pregnancy was 2 days (interquartile range 1-3 days) in the temporizing management group. Mean birthweight was 1435 g after immediate delivery vs 1294 g after temporizing management (P =.14). The adverse perinatal outcome rate was 55% in the immediate delivery group vs 52% in the temporizing management group (relative risk 1.06; 95% confidence interval 0.67-1.70). In both groups there was one neonatal death and no maternal deaths. In the temporizing treatment group, one woman experienced pulmonary edema and one placental abruption. Analyses of only the singleton pregnancies did not result in other outcomes. Conclusions: Early termination of the trial precluded any conclusions for the main outcomes. We observed that temporizing management resulted in a modest prolongation of pregnancy without changes in perinatal and maternal outcome. Conducting a randomized study for this important research question did not prove feasible
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