10 research outputs found
IDENTIFICATION OF TSUNAMIGENIC EARTHQUAKE ZONES IN OCEANIC RIDGES AND TRENCHES
Tsunamigenic earthquakes have been known for their near and far field catastrophic impacts on coastal areas near oceanic ridges and trenches, as well as near tectonic faults in closed and semi-enclosed seas. Not all regions of oceanic ridges and trenches are tsunamigenic earthquake zones, but knowledge of the weighted sum of released earthquake energy and of the Gutenberg-Richter relation of the âaâ and âbâ parameters are needed to better identify them as to their potential for tsunami generation. The present analysis was undertaken in order to better identify tsunamigenic zones near oceanic ridges and trenches in the Mid-Atlantic, in the Pacific, in Chile, in Japan, near the Aleutians and along the Peru-Chile trench. The weighted sum of earthquake energy released and of the Gutenberg-Richter relation parameters were evaluated to identify tsunamigenic earthquake zones along these locations. The present analysis of the Gutenberg-Richter relation of the âaâ and âbâ parameters indicates that tsunamigenic earthquakes do not occur frequently along the Aleutian Trench, although the historic record supports that destructive tsunamis have occurred along this region in the past. Of the oceanic ridges, the results of the present analysis indicate that the Mid-Atlantic Ridge is the most active tsunamigenic zone, while of all the oceanic trenches, the Japan Trench is the most active
Experimental qualification of seismic strengthening of URM buildings in Nepal
Nepalese buildings are typically constructed using unreinforced masonry (URM) as the lateral load-bearing system. In the 2015 Nepal Gorkha earthquake several URM buildings suffered heavy damage. The limited economic resources available in the country and the challenge of strengthening a large portfolio of buildings highlight the need for low-cost retrofitting techniques. This paper presents a large-scale experimental campaign aimed at quantifying the seismic performance of a typical URM wall when strengthened with splints and bandages. This represents one of the retrofit techniques that are most widely-used in Nepal. A 5 Ă 3 m URM wall was constructed using 1:6 cementâsand mortar as per the mechanical properties identified by material testing in Nepal. The URM wall was tested under a two-way ramp cyclic loading. Typical crack patterns associated with URM were observed. The wall was subsequently retrofitted with 8 mm rebars as splints and bandages and tested to failure. The results show that the strength of the retrofitted wall is almost twice that of the URM wall. The observed crack damage improved from EMS-98 Grade 2, with horizontal and diagonal shear cracks in the mortar bed, to Grade 1, with hairline cracks on the rendered splints and bandages. Overall, the experiment demonstrated the efficiency of this practical, low-cost retrofitting technique that is tailored to traditional Nepalese URM buildings. This work can be used to advise local stakeholders in the construction industry as well as to act as a benchmark to improve the reliability of fragility functions for URM buildings in Nepal
Long memory cointegration and dynamic connectedness of volatility in US dollar exchange rates, with FOREX portfolio investment strategy
Decisions of central banks on foreign exchange rates are based on the comovement of foreign exchange (FOREX) in mature markets such as US dollar rates to the British pound, euro, Chinese yuan, Japanese yen and Australian dollar. We investigate the long-run movement and dynamic quantile connectedness of volatility among pairs of these exchange rates. The updated residual-based fractional cointegration testing framework using narrow-band frequency domain least squares estimator is used to obtain the residual series for fractional cointegration. Quantile dynamic connectedness framework for volatility spillovers at different market conditions, depicted by quantiles, are used. We find evidence of long memory cointegration in seven pairs of exchange rates involving the previously mentioned currencies. These seven cases also correspond to a higher average index of quantile connectedness, with the effect of connectedness phasing out at higher quantiles and being more visible at lower quantiles. A portfolio investment strategy using optimal portfolio weights and hedge ratios for maintaining the accrued profit at the FOREX market is also presented
Effects of the <i>In ovo</i> Administration of L-Ascorbic Acid on Tissue L-Ascorbic Acid Concentrations, Systemic Inflammation, and Tracheal Histomorphology of Ross 708 Broilers Subjected to Elevated Levels of Atmospheric Ammonia
The effects of in ovo injection of L-ascorbic acid (L-AA) on tissue L-AA concentrations, systemic inflammation, plasma mineral concentrations, and tracheal histomorphology of Ross 708 broilers subjected to elevated atmospheric ammonia (NH3) levels after hatch were investigated. The four in ovo treatments included non-injected (control), saline-injected (control), or saline containing 12 or 25 mg of L-AA. The in ovo treatments were applied at 17 days of incubation by injecting a 100 ÎŒL volume of each pre-specified treatment into the amnion. At hatch, 12 male chicks were randomly allocated to each of the 12 replicate battery cages belonging to each treatment group. The cages were arranged in a randomized complete block design within a common room. All birds were exposed to 50 ppm of NH3 at 35 days of posthatch age (doa), and the concentration of NH3 in the room was recorded every 20 s. At 0, 7, 14, 21, and 28 doa, one bird from each cage was arbitrarily selected and euthanized for determinations of liver and eye L-AA concentrations at 0, 7, 14, 21, 28 doa; plasma nitric oxide concentrations at 0, 14, 21, and 28 doa; and plasma calcium and trace mineral concentrations at 0 and 21 doa. Tracheal histomorphology evaluations were performed at 0, 21, and 28 doa. There were no significant treatment differences for plasma nitric oxide and mineral concentrations, and for liver and eye L-AA concentrations at each sampling timepoint. In ovo injection of either 12 or 25 mg of L-AA decreased tracheal attenuation incidence at 0 doa compared to the non-injected or saline-injected control groups. Furthermore, the percentage of mild tracheal inflammation scores was lower at 28 doa in response to the in ovo injection of 12 mg of L-AA compared to the non-injected or saline-injected control groups. These results indicate that in ovo injection of 12 mg of L-AA reduces tracheal inflammation in broilers subjected to elevated atmospheric NH3
Impact of the COVID-19 pandemic on patients with paediatric cancer in low-income, middle-income and high-income countries: a multicentre, international, observational cohort study
OBJECTIVES: Paediatric cancer is a leading cause of death for children. Children in low-income and middle-income countries (LMICs) were four times more likely to die than children in high-income countries (HICs). This study aimed to test the hypothesis that the COVID-19 pandemic had affected the delivery of healthcare services worldwide, and exacerbated the disparity in paediatric cancer outcomes between LMICs and HICs. DESIGN: A multicentre, international, collaborative cohort study. SETTING: 91 hospitals and cancer centres in 39 countries providing cancer treatment to paediatric patients between March and December 2020. PARTICIPANTS: Patients were included if they were under the age of 18 years, and newly diagnosed with or undergoing active cancer treatment for Acute lymphoblastic leukaemia, non-Hodgkin's lymphoma, Hodgkin lymphoma, Wilms' tumour, sarcoma, retinoblastoma, gliomas, medulloblastomas or neuroblastomas, in keeping with the WHO Global Initiative for Childhood Cancer. MAIN OUTCOME MEASURE: All-cause mortality at 30 days and 90 days. RESULTS: 1660 patients were recruited. 219 children had changes to their treatment due to the pandemic. Patients in LMICs were primarily affected (n=182/219, 83.1%). Relative to patients with paediatric cancer in HICs, patients with paediatric cancer in LMICs had 12.1 (95% CI 2.93 to 50.3) and 7.9 (95% CI 3.2 to 19.7) times the odds of death at 30 days and 90 days, respectively, after presentation during the COVID-19 pandemic (p<0.001). After adjusting for confounders, patients with paediatric cancer in LMICs had 15.6 (95% CI 3.7 to 65.8) times the odds of death at 30 days (p<0.001). CONCLUSIONS: The COVID-19 pandemic has affected paediatric oncology service provision. It has disproportionately affected patients in LMICs, highlighting and compounding existing disparities in healthcare systems globally that need addressing urgently. However, many patients with paediatric cancer continued to receive their normal standard of care. This speaks to the adaptability and resilience of healthcare systems and healthcare workers globally
Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries
Background
Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks.
Methods
The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned.
Results
A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31).
Conclusion
Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)