343 research outputs found

    Scenario dependence of linear site-effect factors for short-period response spectral ordinates

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    Ground‐motion models for response spectral ordinates commonly partition site‐response effects into linear and nonlinear components. The nonlinear components depend upon the earthquake scenario being considered implicitly through the use of the expected level of excitation at some reference horizon. The linear components are always assumed to be independent of the earthquake scenario. This article presents empirical and numerical evidence as well as a theoretical explanation for why the linear component of site response depends upon the magnitude and distance of the earthquake scenario. Although the impact is most pronounced for small‐magnitude scenarios, the finding has significant implications for a number of applications of more general interest including the development of site‐response terms within ground‐motion models, the estimation of ground‐motion variability components ϕS2SϕS2S and ϕSSϕSS , the construction of partially nonergodic models for site‐specific hazard assessments, and the validity of the convolution approach for computing surface hazard curves from those at a reference horizon, among others. All of these implications are discussed in the present article

    Developing a model for the prediction of ground motions due to earthquakes in the Groningen gas field

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    Major efforts are being undertaken to quantify seismic hazard and risk due to production-induced earthquakes in the Groningen gas field as the basis for rational decision-making about mitigation measures. An essential element is a model to estimate surface ground motions expected at any location for each earthquake originating within the gas reservoir. Taking advantage of the excellent geological and geophysical characterisation of the field and a growing database of ground-motion recordings, models have been developed for predicting response spectral accelerations, peak ground velocity and ground-motion durations for a wide range of magnitudes. The models reflect the unique source and travel path characteristics of the Groningen earthquakes, and account for the inevitable uncertainty in extrapolating from the small observed magnitudes to potential larger events. The predictions of ground-motion amplitudes include the effects of nonlinear site response of the relatively soft near-surface deposits throughou t the field

    Ultrasound-Guided Placement of a Renal Artery Stent Using an Intracardiac Probe for Transvascular Imaging

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    In this set of images obtained during an experimental study using a porcine animal model, we introduce ultrasound guidance of percutaneous transluminal renal angioplasty and renal stenting. A state-of-the-art intracardiac ultrasound catheter is used here for transvascular scanning from within the lumen of the abdominal aorta, thus providing a field of view for navigation of a balloon catheter and a wire coil (“stent”) into each renal artery of a pig. This study is intended as a contribution to the growing field of minimally invasive interventions and their navigation by non-ionizing ultrasound imaging

    Liquefaction hazard of the Groningen region of the Netherlands due to induced seismicity

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    The operator of the Groningen gas field is leading an effort to quantify the seismic hazard and riskof the region due to induced earthquakes, includingoverseeing one of the most comprehensive liquefaction hazard studies performedgloballyto date. Due tothe unique characteristics of the seismic hazard and the geologic deposits in Groningen, efforts first focused on developing relationships for a Groningen-specific liquefaction triggering model. The liquefaction hazard was then assessedusing a Monte Carlo method, wherein a range of credibleevent scenarios were considered in computingliquefaction damage-potentialhazard curves. Thiseffort entailed the use of a regional stochastic seismic source model,ground motion prediction equation,site response model,and geologic model that were developed as part of the broader regional seismic hazardassessment.“No-to-Minor Surficial Liquefaction Manifestations”arepredicted for mostsites across the study areafor a 75-year return period. The only sites where “Moderate Surficial Liquefaction Manifestations” are predicted are in the town of Zandeweer, with only some of the sites in the townbeing predicted to experience this severityof liquefactionfor thisreturn period

    Capturing spatial variability in the regional Ground Motion Model of Groningen, the Netherlands

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    Long-term exploration of the Groningen gas field in the Netherlands led to induced seismicity. Over the past nine years, an increasingly sophisticated Ground Motion Model (GMM) has been developed to assess the site response and the related seismic hazard. The GMM output strongly depends on the shear-wave velocity (VS), among other input parameters. To date, VS model data from soil profiles (Kruiver et al., Bulletin of Earthquake Engineering, 15(9): 3555–3580, 2017; Netherlands Journal of Geosciences, 96(5): s215–s233, 2017) have been used in the GMM. Recently, new VS profiles above the Groningen gas field were constructed using ambient noise surface wave tomography. These so-called field VS data, even though spatially limited, provide an independent source of VS to check whether the level of spatial variability in the GMM is sufficient. Here, we compared amplification factors (AF) for two sites (Borgsweer and Loppersum) calculated with the model VS and the field VS (Chmiel et al., Geophysical Journal International, 218(3), 1781–1795, 2019 and new data). Our AF results over periods relevant for seismic risk (0.01–1.0 s) show that model and field VS profiles agree within the uncertainty range generally accepted in geo-engineering. In addition, we compared modelled spectral accelerations using either field VS or model VS in Loppersum to the recordings of an earthquake that occurred during the monitoring period (ML 3.4 Zeerijp on 8 January 2018). The modelled spectral accelerations at the surface for both field VS and model VS are coherent with the earthquake data for the resonance periods representative of most buildings in Groningen (T = 0.2 and 0.3 s). These results confirm that the currently used VS model in the GMM captures spatial variability in the site response and represents reliable input for the site response calculations

    Collaborative research between clinicians and researchers: a multiple case study of implementation

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    <p>Abstract</p> <p>Background</p> <p>Bottom-up, clinician-conceived and directed clinical intervention research, coupled with collaboration from researcher experts, is conceptually endorsed by the participatory research movement. This report presents the findings of an evaluation of a program in the Veterans Health Administration meant to encourage clinician-driven research by providing resources believed to be critical. The evaluation focused on the extent to which funded projects: maintained integrity to their original proposals; were methodologically rigorous; were characterized by collaboration between partners; and resulted in sustained clinical impact.</p> <p>Methods</p> <p>Researchers used quantitative (survey and archival) and qualitative (focus group) data to evaluate the implementation, evaluation, and sustainability of four clinical demonstration projects at four sites. Fourteen research center mentors and seventeen clinician researchers evaluated the level of collaboration using a six-dimensional model of participatory research.</p> <p>Results</p> <p>Results yielded mixed findings. Qualitative and quantitative data suggested that although the process was collaborative, clinicians' prior research experience was critical to the quality of the projects. Several challenges were common across sites, including subject recruitment, administrative support and logistics, and subsequent dissemination. Only one intervention achieved lasting clinical effect beyond the active project period. Qualitative analyses identified barriers and facilitators and suggested areas to improve sustainability.</p> <p>Conclusions</p> <p>Evaluation results suggest that this participatory research venture was successful in achieving clinician-directed collaboration, but did not produce sustainable interventions due to such implementation problems as lack of resources and administrative support.</p

    Interactive effects of mGlu5 and 5-HT2A receptors on locomotor activity in mice

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    RationaleMetabotropic glutamate (mGlu) receptors have been suggested to play a role in neuropsychiatric disorders including schizophrenia, drug abuse, and depression. Because serotonergic hallucinogens increase glutamate release and mGlu receptors modulate the response to serotonin (5-HT)(2A) activation, the interactions between serotonin 5-HT(2A) receptors and mGlu receptors may prove to be important for our understanding of these diseases.ObjectiveWe tested the effects of the serotonergic hallucinogen and 5-HT(2A) agonist, 2,5-dimethoxy-4-methylamphetamine (DOM), and the selective 5-HT(2A) antagonist, M100907, on locomotor activity in the mouse behavioral pattern monitor (BPM) in mGlu5 wild-type (WT) and knockout (KO) mice on a C57 background.ResultsBoth male and female mGlu5 KO mice showed locomotor hyperactivity and diminished locomotor habituation compared with their WT counterparts. Similarly, the mGlu5-negative allosteric modulator 2-methyl-6-(phenylethynyl)pyridine (MPEP) also increased locomotor hyperactivity, which was absent in mGlu5 KO mice. The locomotor hyperactivity in mGlu5 receptor KO mice was potentiated by DOM (0.5 mg/kg, subcutaneously (SC)) and attenuated by M100907 (1.0 mg/kg, SC). M100907 (0.1 mg/kg, SC) also blocked the hyperactivity induced by MPEP.ConclusionsThese studies demonstrated that loss of mGlu5 receptor activity either pharmacologically or through gene deletion leads to locomotor hyperactivity in mice. Additionally, the gene deletion of mGlu5 receptors increased the behavioral response to the 5-HT(2A) agonist DOM, suggesting that mGlu5 receptors either mitigate the behavioral effects of 5-HT(2A) hallucinogens or that mGlu5 KO mice show an increased sensitivity to 5-HT(2A) agonists. Taken together, these studies indicate a functional interaction between mGlu5 and 5-HT(2A) receptors

    Patient Satisfaction with Primary Care Office-Based Buprenorphine/Naloxone Treatment

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    BACKGROUND: Factors associated with satisfaction among patients receiving primary care–based buprenorphine/naloxone are unknown. OBJECTIVE: To identify factors related to patient satisfaction in patients receiving primary care–based buprenorphine/naloxone that varied in counseling intensity (20 vs 45 minutes) and office visit frequency (weekly vs thrice weekly). DESIGN AND PARTICIPANTS: One hundred and forty-two opioid-dependent subjects. MEASUREMENTS: Demographics, drug treatment history, and substance use status at baseline and during treatment were collected. The primary outcome was patient satisfaction at 12 weeks. RESULTS: Patients’ mean overall satisfaction score was 4.4 (out of 5). Patients were most satisfied with the medication and ancillary services and indicated strong willingness to refer a substance-abusing friend for the same treatment. Patients were least satisfied with their interactions with other opioid-dependent patients, referrals to Narcotics Anonymous, and the inconvenience of the treatment location. Female gender (β = .17, P = .04) and non-White ethnicity/race (β = .17, P = .04) independently predicted patient satisfaction. Patients who received briefer counseling and buprenorphine/naloxone dispensed weekly had greater satisfaction than those whose medication was dispensed thrice weekly (mean difference 4.9, 95% confidence interval 0.08 to 9.80, P = .03). CONCLUSIONS: Patients are satisfied with primary care office-based buprenorphine/naloxone. Providers should consider the identified barriers to patient satisfaction
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