389 research outputs found

    Evidence for Anthropogenic Surface Loading as Trigger Mechanism of the 2008 Wenchuan Earthquake

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    Two and a half years prior to China's M7.9 Wenchuan earthquake of May 2008, at least 300 million metric tons of water accumulated with additional seasonal water level changes in the Minjiang River Valley at the eastern margin of the Longmen Shan. This article shows that static surface loading in the Zipingpu water reservoir induced Coulomb failure stresses on the nearby Beichuan thrust fault system at <17km depth. Triggering stresses exceeded levels of daily lunar and solar tides and perturbed a fault area measuring 416+/-96km^2. These stress perturbations, in turn, likely advanced the clock of the mainshock and directed the initial rupture propagation upward towards the reservoir on the "Coulomb-like" Beichuan fault with rate-and-state dependent frictional behavior. Static triggering perturbations produced up to 60 years (0.6%) of equivalent tectonic loading, and show strong correlations to the coseismic slip. Moreover, correlations between clock advancement and coseismic slip, observed during the mainshock beneath the reservoir, are strongest for a longer seismic cycle (10kyr) of M>7 earthquakes. Finally, the daily event rate of the micro-seismicity (M>0.5) correlates well with the static stress perturbations, indicating destabilization.Comment: 22 pages, 4 figures, 3 table

    Hydrogen for synthetic fuels via nuclear energy

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    Fluctuations in availability and recent increases in price of petroleum have had profound effects on the national economy. As synthetic fuels, in particular, hydrogen, become increasingly attractive, nuclear energy has a role in developing such fuels. It is postulated that the nuclear radiation of the fission process itself can be utilized directly in fluid fueled devices or radiation and heat can be used in special purpose solid-fuel reactors. Both fusion and fission are considered in this light.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44905/1/10894_2005_Article_BF01063684.pd

    Smooth Muscle Myosin Inhibition: A Novel Therapeutic Approach for Pulmonary Hypertension

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    Pulmonary hypertension remains a major clinical problem despite current therapies. In this study, we examine for the first time a novel pharmacological target, smooth muscle myosin, and determine if the smooth muscle myosin inhibitor, CK-2019165 (CK-165) ameliorates pulmonary hypertension.Six domestic female pigs were surgically instrumented to measure pulmonary blood flow and systemic and pulmonary vascular dynamics. Pulmonary hypertension was induced by hypoxia, or infusion of the thromboxane analog (U-46619, 0.1 ”g/kg/min, i.v.). In rats, chronic pulmonary hypertension was induced by monocrotaline.CK-165 (4 mg/kg, i.v.) reduced pulmonary vascular resistance by 22±3 and 28±6% from baseline in hypoxia and thromboxane pig models, respectively (p<0.01 and 0.01), while mean arterial pressure also fell and heart rate rose slightly. When CK-165 was delivered via inhalation in the hypoxia model, pulmonary vascular resistance fell by 17±6% (p<0.05) while mean arterial pressure and heart rate were unchanged. In the monocrotaline model of chronic pulmonary hypertension, inhaled CK-165 resulted in a similar (18.0±3.8%) reduction in right ventricular systolic pressure as compared with sildenafil (20.3±4.5%).Inhibition of smooth muscle myosin may be a novel therapeutic target for treatment of pulmonary hypertension

    Seismogenic zone structure of the southern Middle America Trench, Costa Rica

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    The shallow seismogenic portion of subduction zones generates damaging large and great earthquakes. This study provides structural constraints on the seismogenic zone of the Middle America Trench offshore central Costa Rica and insights into the physical and mechanical characteristics controlling seismogenesis. We have located ~300 events that occurred following the MW 6.9, 20 August 1999, Quepos, Costa Rica, underthrusting earthquake using a three-dimensional velocity model and arrival time data recorded by a temporary local network of land and ocean bottom seismometers. We use aftershock locations to define the geometry and characteristics of the seismogenic zone in this region. These events define a plane dipping at 19° that marks the interface between the Cocos Plate and the Panama Block. The majority of aftershocks occur below 10 km and above 30 km depth below sea level, corresponding to 30–35 km and 95 km from the trench axis, respectively. Relative event relocation produces a seismicity pattern similar to that obtained using absolute locations, increasing confidence in the geometry of the seismogenic zone. The aftershock locations spatially correlate with the downdip extension of the oceanic Quepos Plateau and reflect the structure of the main shock rupture asperity. This strengthens an earlier argument that the 1999 Quepos earthquake ruptured specific bathymetric highs on the downgoing plate. We believe that subduction of this highly disrupted seafloor has established a set of conditions which presently limit the seismogenic zone to be between 10 and 35 km below sea level

    Rural High North: A High Rate of Fatal Injury and Prehospital Death

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    Finnmark County is the northernmost county in Norway. For several decades, the rate of mortality after injury in this sparsely inhabited region has remained above the national average. Following documentation of this discrepancy for the period 1991–1995, improvements to the trauma system were implemented. The present study aims to assess whether trauma-related mortality rates have subsequently improved. All injury-associated fatalities in Finnmark from 1995–2004 were identified retrospectively from the National Registry of Death and reviewed. Low-energy trauma in elderly individuals and poisonings were excluded. A total of 453 cases of trauma-related death occurred during the study period, and 327 of those met the inclusion criteria. Information was retrievable for 266 cases. The majority of deaths (86%) occurred in the prehospital phase. The main causes of death were suicide (33%) and road traffic accidents (21%). Drowning and snowmobile injuries accounted for an unexpectedly high proportion (12 and 8%, respectively). The time of death did not show trimodal distribution. Compared to the previous study period, there was a significant overall decline in injury-related mortality, yet there was no change in place of death, mechanism of injury, or time from injury until death. Changes in injury-related mortality cannot be linked to improvements in the trauma system. There was no change in the epidemiological patterns of injury. The high rate of on-scene mortality indicates that any major improvement in the number of injury-related deaths lies in targeted prevention

    Factors Affecting COVID-19 Outcomes in Cancer Patients: A First Report From Guy's Cancer Center in London

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    Background: There is insufficient evidence to support clinical decision-making for cancer patients diagnosed with COVID-19 due to the lack of large studies. Methods: We used data from a single large UK Cancer Center to assess the demographic/clinical characteristics of 156 cancer patients with a confirmed COVID-19 diagnosis between 29 February and 12 May 2020. Logistic/Cox proportional hazards models were used to identify which demographic and/or clinical characteristics were associated with COVID-19 severity/death. Results: 128 (82%) presented with mild/moderate COVID-19 and 28 (18%) with a severe case of the disease. An initial cancer diagnosis >24 months before COVID-19 [OR: 1.74 (95% CI: 0.71–4.26)], presenting with fever [6.21 (1.76–21.99)], dyspnea [2.60 (1.00–6.76)], gastro-intestinal symptoms [7.38 (2.71–20.16)], or higher levels of C-reactive protein [9.43 (0.73–121.12)] were linked with greater COVID-19 severity. During a median follow-up of 37 days, 34 patients had died of COVID-19 (22%). Being of Asian ethnicity [3.73 (1.28–10.91)], receiving palliative treatment [5.74 (1.15–28.79)], having an initial cancer diagnosis >24 months before [2.14 (1.04–4.44)], dyspnea [4.94 (1.99–12.25)], and increased CRP levels [10.35 (1.05–52.21)] were positively associated with COVID-19 death. An inverse association was observed with increased levels of albumin [0.04 (0.01–0.04)]. Conclusions: A longer-established diagnosis of cancer was associated with increased severity of infection as well as COVID-19 death, possibly reflecting the effects a more advanced malignant disease has on this infection. Asian ethnicity and palliative treatment were also associated with COVID-19 death in cancer patients

    New Trial Designs and Potential Therapies for Pulmonary Artery Hypertension

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    A greater understanding of the epidemiology, pathogenesis, and pathophysiology of pulmonary artery hypertension (PAH) has led to significant advances, but the disease remains fatal. Treatment options are neither universally available nor always effective, underscoring the need for development of novel therapies and therapeutic strategies. Clinical trials to date have provided evidence of efficacy, but were limited in evaluating the scope and duration of treatment effects. Numerous potential targets in varied stages of drug development exist, in addition to novel uses of familiar therapies. The pursuit of gene and cell-based therapy continues, and device use to help acute deterioration and chronic management is emerging. This rapid surge of drug development has led to multicenter pivotal clinical trials and has resulted in novel ethical and global clinical trial concerns. This paper will provide an overview of the opportunities and challenges that await the development of novel treatments for PAH. A greater understanding of the epidemiology, pathogenesis, and pathophysiology of pulmonary artery hypertension (PAH) has led to significant advances over the past 2 decades in treatment of this disorder. However, these treatment options are neither universally available nor always effective, underscoring the need for development of novel therapies and therapeutic strategies. Because PAH is considered an orphan disease that is uniformly progressive and fatal, prior clinical trials evaluating novel therapies were relatively short in duration and were comprised of small populations of affected patients. These studies provided evidence of efficacy, but were limited in evaluating the scope and duration of treatment effects. Accordingly, clinical development of novel therapies for PAH in the future will require trials of larger and perhaps more diverse patient cohorts who are studied for longer periods and with more robust and meaningful efficacy endpoints. The challenges posed by these requirements are substantial, and include From th

    Fluid release from the subducted Cocos plate and partial melting of the crust deduced from magnetotelluric studies in southern Mexico: implications for the generation of volcanism and subduction dynamics

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    In order to study electrical conductivity phenomena that are associated with subduction related fluid release and melt production, magnetotelluric (MT) measurements were carried out in southern Mexico along two coast to coast profiles. The conductivity-depth distribution was obtained by simultaneous two-dimensional inversion of the transverse magnetic and transverse electric modes of the magnetotelluric transfer functions. The MT models demonstrate that the plate southern profile shows enhanced conductivity in the deep crust. The northern profile is dominated by an elongated conductive zone extending >250 km below the Trans-Mexican Volcanic Belt (TMVB). The isolated conductivity anomalies in the southern profile are interpreted as slab fluids stored in the overlying deep continental crust. These fluids were released by progressive metamorphic dehydration of the basaltic oceanic crust. The conductivity anomalies may be related to the main dehydration reactions at the zeolite → blueschist → eclogite facies transitions and the breakdown of chlorite. This relation allows the estimation of a geothermal gradient of ∌8.5°C/km for the top of the subducting plate. The same dehydration reactions may be recognized along the northern profile at the same position relative to the depth of the plate, but more inland due to a shallower dip, and merge near the volcanic front due to steep downbending of the plate. When the oceanic crust reaches a depth of 80–90 km, ascending fluids produce basaltic melts in the intervening hot subcontinental mantle wedge that give rise to the volcanic belt. Water-rich basalts may intrude into the lower continental crust leading to partial melting. The elongated highly conductive zone below the TMVB may therefore be caused by partial melts and fluids of various origins, ongoing migmatization, ascending basaltic and granitic melts, growing plutons as well as residual metamorphic fluids. Zones of extremely high conductance (>8000 S) in the continental crust on either MT profile might indicate extinct magmatism
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