300 research outputs found
Lower edge of locked Main Himalayan Thrust unzipped by the 2015 Gorkha earthquake
Large earthquakes are thought to release strain on previously locked faults. However, the details of how earthquakes are initiated, grow and terminate in relation to pre-seismically locked and creeping patches is unclear ^1-4. The 2015 Mw 7.8 Gorkha, Nepal earthquake occurred close to Kathmandu in a region where the prior pattern of fault locking is well documented ^5. Here we analyze this event using seismological records measured at teleseismic distances and Synthetic Aperture Radar imagery. We show that the earthquake originated northwest of Kathmandu within a cluster of background seismicity that fringes the bottom of the locked portion of the Main Himalayan Thrust fault (MHT). The rupture propagated eastwards for about 140 km, unzipping the lower edge of the locked portion of the fault. High-frequency seismic waves radiated continuously as the slip pulse propagated at about 2.8 km s-1 along this zone of presumably high and heterogeneous pre-¬seismic stress at the seismic-aseismic transition. Eastward unzipping of the fault resumed during the Mw 7.3 aftershock on May 12. The transfer of stress to neighbouring regions during the Gorkha earthquake should facilitate future rupture of the areas of the MHT adjacent and up-dip of the Gorkha earthquake rupture.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ngeo251
How environmental managers perceive and approach the issue of invasive species: the case of Japanese knotweed s.l. (Rhône River, France)
We would like to thank Springer for publishing our article. The final publication is available at http://link.springer.com/article/10.1007%2Fs10530-015-0969-1International audienceStudying the perceptions of stakeholders or interested parties is a good way to better understand behaviours and decisions. This is especially true for the management of invasive species such as Japanese knotweed s.l. This plant has spread widely in the Rhône basin, where significant financial resources have been devoted to its management. However, no control technique is recognized as being particularly effective. Many uncertainties remain and many documents have been produced by environmental managers to disseminate current knowledge about the plant and its management. This article aims at characterizing the perceptions that environmental managers have of Japanese knotweed s.l. A discourse analysis was conducted on the printed documentation produced about Japanese knotweed s.l. by environmental managers working along the Rhône River (France). The corpus was both qualitatively and quantitatively analysed. The results indicated a diversity of perceptions depending on the type of environmental managers involved, as well as the geographicalareas and scales on which they acted. Whereas some focused on general knowledge relating to the origins and strategies of colonization, others emphasized the diversity and efficacy of the prospective eradication techniques. There is a real interest in implementing targeted actions to meet local issues. To do so, however, these issues must be better defined. This is a challenging task, as it must involve all types of stakeholders
Impact of Changes to National Hypertension Guidelines on Hypertension Management and Outcomes in the United Kingdom
In recent years, national and international guidelines have recommended the use of out-of-office blood pressure monitoring for diagnosing hypertension. Despite evidence of cost-effectiveness, critics expressed concerns this would increase cardiovascular morbidity. We assessed the impact of these changes on the incidence of hypertension, out-of-office monitoring and cardiovascular morbidity using routine clinical data from English general practices, linked to inpatient hospital, mortality, and socio-economic status data. We studied 3 937 191 adults with median follow-up of 4.2 years (49% men, mean age=39.7 years) between April 1, 2006 and March 31, 2017. Interrupted time series analysis was used to examine the impact of changes to English hypertension guidelines in 2011 on incidence of hypertension (primary outcome). Secondary outcomes included rate of out-of-office monitoring and cardiovascular events. Across the study period, incidence of hypertension fell from 2.1 to 1.4 per 100 person-years. The change in guidance in 2011 was not associated with an immediate change in incidence (change in rate=0.01 [95% CI, -0.18-0.20]) but did result in a leveling out of the downward trend (change in yearly trend =0.09 [95% CI, 0.04-0.15]). Ambulatory monitoring increased significantly in 2011/2012 (change in rate =0.52 [95% CI, 0.43-0.60]). The rate of cardiovascular events remained unchanged (change in rate =-0.02 [95% CI, -0.05-0.02]). In summary, changes to hypertension guidelines in 2011 were associated with a stabilisation in incidence and no increase in cardiovascular events. Guidelines should continue to recommend out-of-office monitoring for diagnosis of hypertension
Effectiveness of strategies to increase the validity of findings from association studies: size vs. replication
<p>Abstract</p> <p>Background</p> <p>The capacity of multiple comparisons to produce false positive findings in genetic association studies is abundantly clear. To address this issue, the concept of false positive report probability (FPRP) measures "the probability of no true association between a genetic variant and disease given a statistically significant finding". This concept involves the notion of prior probability of an association between a genetic variant and a disease, making it difficult to achieve acceptable levels for the FPRP when the prior probability is low. Increasing the sample size is of limited efficiency to improve the situation.</p> <p>Methods</p> <p>To further clarify this problem, the concept of true report probability (TRP) is introduced by analogy to the positive predictive value (PPV) of diagnostic testing. The approach is extended to consider the effects of replication studies. The formula for the TRP after k replication studies is mathematically derived and shown to be only dependent on prior probability, alpha, power, and number of replication studies.</p> <p>Results</p> <p>Case-control association studies are used to illustrate the TRP concept for replication strategies. Based on power considerations, a relationship is derived between TRP after k replication studies and sample size of each individual study. That relationship enables study designers optimization of study plans. Further, it is demonstrated that replication is efficient in increasing the TRP even in the case of low prior probability of an association and without requiring very large sample sizes for each individual study.</p> <p>Conclusions</p> <p>True report probability is a comprehensive and straightforward concept for assessing the validity of positive statistical testing results in association studies. By its extension to replication strategies it can be demonstrated in a transparent manner that replication is highly effective in distinguishing spurious from true associations. Based on the generalized TRP method for replication designs, optimal research strategy and sample size planning become possible.</p
Racism as a determinant of health: a systematic review and meta-analysis
Despite a growing body of epidemiological evidence in recent years documenting the health impacts of racism, the cumulative evidence base has yet to be synthesized in a comprehensive meta-analysis focused specifically on racism as a determinant of health. This meta-analysis reviewed the literature focusing on the relationship between reported racism and mental and physical health outcomes. Data from 293 studies reported in 333 articles published between 1983 and 2013, and conducted predominately in the U.S., were analysed using random effects models and mean weighted effect sizes. Racism was associated with poorer mental health (negative mental health: r = -.23, 95% CI [-.24,-.21], k = 227; positive mental health: r = -.13, 95% CI [-.16,-.10], k = 113), including depression, anxiety, psychological stress and various other outcomes. Racism was also associated with poorer general health (r = -.13 (95% CI [-.18,-.09], k = 30), and poorer physical health (r = -.09, 95% CI [-.12,-.06], k = 50). Moderation effects were found for some outcomes with regard to study and exposure characteristics. Effect sizes of racism on mental health were stronger in cross-sectional compared with longitudinal data and in non-representative samples compared with representative samples. Age, sex, birthplace and education level did not moderate the effects of racism on health. Ethnicity significantly moderated the effect of racism on negative mental health and physical health: the association between racism and negative mental health was significantly stronger for Asian American and Latino(a) American participants compared with African American participants, and the association between racism and physical health was significantly stronger for Latino(a) American participants compared with African American participants.<br /
The association between antihypertensive treatment and serious adverse events by age and frailty: A cohort study
Background
Antihypertensives are effective at reducing the risk of cardiovascular disease, but limited data exist quantifying their association with serious adverse events, particularly in older people with frailty. This study aimed to examine this association using nationally representative electronic health record data.
Methods and findings
This was a retrospective cohort study utilising linked data from 1,256 general practices across England held within the Clinical Practice Research Datalink between 1998 and 2018. Included patients were aged 40+ years, with a systolic blood pressure reading between 130 and 179 mm Hg, and not previously prescribed antihypertensive treatment. The main exposure was defined as a first prescription of antihypertensive treatment. The primary outcome was hospitalisation or death within 10 years from falls. Secondary outcomes were hypotension, syncope, fractures, acute kidney injury, electrolyte abnormalities, and primary care attendance with gout. The association between treatment and these serious adverse events was examined by Cox regression adjusted for propensity score. This propensity score was generated from a multivariable logistic regression model with patient characteristics, medical history and medication prescriptions as covariates, and new antihypertensive treatment as the outcome. Subgroup analyses were undertaken by age and frailty. Of 3,834,056 patients followed for a median of 7.1 years, 484,187 (12.6%) were prescribed new antihypertensive treatment in the 12 months before the index date (baseline). Antihypertensives were associated with an increased risk of hospitalisation or death from falls (adjusted hazard ratio [aHR] 1.23, 95% confidence interval (CI) 1.21 to 1.26), hypotension (aHR 1.32, 95% CI 1.29 to 1.35), syncope (aHR 1.20, 95% CI 1.17 to 1.22), acute kidney injury (aHR 1.44, 95% CI 1.41 to 1.47), electrolyte abnormalities (aHR 1.45, 95% CI 1.43 to 1.48), and primary care attendance with gout (aHR 1.35, 95% CI 1.32 to 1.37). The absolute risk of serious adverse events with treatment was very low, with 6 fall events per 10,000 patients treated per year. In older patients (80 to 89 years) and those with severe frailty, this absolute risk was increased, with 61 and 84 fall events per 10,000 patients treated per year (respectively). Findings were consistent in sensitivity analyses using different approaches to address confounding and taking into account the competing risk of death. A strength of this analysis is that it provides evidence regarding the association between antihypertensive treatment and serious adverse events, in a population of patients more representative than those enrolled in previous randomised controlled trials. Although treatment effect estimates fell within the 95% CIs of those from such trials, these analyses were observational in nature and so bias from unmeasured confounding cannot be ruled out.
Conclusions
Antihypertensive treatment was associated with serious adverse events. Overall, the absolute risk of this harm was low, with the exception of older patients and those with moderate to severe frailty, where the risks were similar to the likelihood of benefit from treatment. In these populations, physicians may want to consider alternative approaches to management of blood pressure and refrain from prescribing new treatment
Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth's D" layer
The Earth's lower mantle is believed to be composed mainly of (Mg,Fe)SiO3
perovskite, with lesser amounts of (Mg,Fe)O and CaSiO3). But it has not been
possible to explain many unusual properties of the lowermost 150 km of the
mantle (the D" layer) with this mineralogy. Here, using ab initio simulations
and high-pressure experiments, we show that at pressures and temperatures of
the D" layer, MgSiO3 transforms from perovskite into a layered CaIrO3-type
post-perovskite phase. The elastic properties of the post-perovskite phase and
its stability field explain several observed puzzling properties of the D"
layer: its seismic anisotropy, the strongly undulating shear-wave discontinuity
at its top and possibly the anticorrelation between shear and bulk sound
velocities.Comment: PUBLISHED IN Nature 430, 445-448 (2004
Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake
The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ~48 m, up to ~35 m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment
Neoadjuvant capecitabine, radiotherapy, and bevacizumab (CRAB) in locally advanced rectal cancer: results of an open-label phase II study
<p>Abstract</p> <p>Background</p> <p>Preoperative capecitabine-based chemoradiation is a standard treatment for locally advanced rectal cancer (LARC). Here, we explored the safety and efficacy of the addition of bevacizumab to capecitabine and concurrent radiotherapy for LARC.</p> <p>Methods</p> <p>Patients with MRI-confirmed stage II/III rectal cancer received bevacizumab 5 mg/kg i.v. 2 weeks prior to neoadjuvant chemoradiotherapy followed by bevacizumab 5 mg/kg on Days 1, 15 and 29, capecitabine 825 mg/m<sup>2 </sup>twice daily on Days 1-38, and concurrent radiotherapy 50.4 Gy (1.8 Gy/day, 5 days/week for 5 weeks + three 1.8 Gy/day), starting on Day 1. Total mesorectal excision was scheduled 6-8 weeks after completion of chemoradiotherapy. Tumour regression grades (TRG) were evaluated on surgical specimens according to Dworak. The primary endpoint was pathological complete response (pCR).</p> <p>Results</p> <p>61 patients were enrolled (median age 60 years [range 31-80], 64% male). Twelve patients (19.7%) had T3N0 tumours, 1 patient T2N1, 19 patients (31.1%) T3N1, 2 patients (3.3%) T2N2, 22 patients (36.1%) T3N2 and 5 patients (8.2%) T4N2. Median tumour distance from the anal verge was 6 cm (range 0-11). Grade 3 adverse events included dermatitis (n = 6, 9.8%), proteinuria (n = 4, 6.5%) and leucocytopenia (n = 3, 4.9%). Radical resection was achieved in 57 patients (95%), and 42 patients (70%) underwent sphincter-preserving surgery. TRG 4 (pCR) was recorded in 8 patients (13.3%) and TRG 3 in 9 patients (15.0%). T-, N- and overall downstaging rates were 45.2%, 73.8%, and 73.8%, respectively.</p> <p>Conclusions</p> <p>This study demonstrates the feasibility of preoperative chemoradiotherapy with bevacizumab and capecitabine. The observed adverse events of neoadjuvant treatment are comparable with those previously reported, but the pCR rate was lower.</p
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