5,269 research outputs found

    Transmission of PhC coupled-resonator waveguide (PhCCRW) structure enhanced via mode matching

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    A method for increasing the coupling efficiency between ridge optical waveguides and PhCCRWs is described. This increase is achieved via W1 channel waveguide sections, formed within a two-dimensional triangular lattice photonic crystal using mode-matching. The mode-matching is achieved by low quality-factor modified cavities added to both the input and output ports of the PhCCRW. A three dimensional finite-difference time-domain method has been used to simulate light propagation through the modified PhCCRW. We have fabricated PhCCRWs working at 1.5”m in silicon-on-insulator material. Measurements and simulations show that the overall transmission is improved by a factor of two

    Technological and infrastructure collaborative seismic research in Western Mexico

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    In February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, a region with a high occurrence of large earthquakes (> Mw = 7.5) and tsunami generation, on board the British Royal Research Ship James Cook. This successful joint cruise, named TSUJAL, was made possible thanks to a cooperative agreement between NERC and CSIC as part of the Ocean Facilities Exchange Group (OFEG), a major forum of European oceanographic institutions for the exchange of ship time, equipment and personnel. A dense geophysical data set was acquired using for the first time 6 km length seismic streamer facilities from Spain’s Consejo Superior de Investigaciones Cientificas (CSIC), usually operating in the Spanish RV Sarmiento de Gamboa, onboard the British RRS James Cook by solving all mechanical, electrical and electronic problems. The RRS James Cook in turn provides the seismic source and the acoustic, hullmounted echosounder operated by the British Natural Environment Research Council (NERC). Multiscale seismic and echosounder images unravel the subduction geometry, nature of the crust, and evidence faults and mass wasting processes. The data are crucial to estimating fault seismic parameters, and these parameters are critical to carrying out seismic hazard in Mexico, especially when considering largemagnitude earthquakes (Mw 8.0), and to constrain tsunami models.Peer Reviewe

    Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being

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    This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics

    Magma displacements under insular volcanic fields, applications to eruption forecasting: El Hierro, Canary Islands, 2011-2013

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    Significant deformations, followed by increased seismicity detected since 2011 July at El Hierro, Canary Islands, Spain, prompted the deployment of additional monitoring equipment. The climax of this unrest was a submarine eruption first detected on 2011 October 10, and located at about 2 km SW of La Restinga, southernmost village of El Hierro Island. The eruption ceased on 2012 March 5, after the volcanic tremor signals persistently weakened through 2012 February. However, the seismic activity did not end with the eruption, as several other seismic crises followed. The seismic episodes presented a characteristic pattern: over a few days the number and magnitude of seismic event increased persistently, culminating in seismic events severe enough to be felt all over the island. Those crises occurred in 2011 November, 2012 June and September, 2012 December to 2013 January and in 2013 March-April. In all cases the seismic unrest was preceded by significant deformations measured on the island's surface that continued during the whole episode. Analysis of the available GPS and seismic data suggests that several magma displacement processes occurred at depth from the beginning of the unrest. The first main magma movement or 'injection' culminated with the 2011 October submarine eruption. A model combining the geometry of the magma injection process and the variations in seismic energy release has allowed successful forecasting of the new-vent opening.CSIC [2011-30E070]; MINECO [CGL2011-28682-C02-01]; bilateral UNAM (Mexico) - CSIC (Spain) program; Mayor's Office of El Pinar de El Hierroinfo:eu-repo/semantics/publishedVersio

    Serum Ferritin Levels Lack Diagnostic Accuracy for Liver Fibrosis in Patients With Nonalcoholic Fatty Liver Disease

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    BACKGROUND & AIM: Series studies have associated increased serum levels of ferritin with liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD). We aimed to determine the accuracy with which measurements of serum ferritin determine the presence and severity of liver fibrosis, and whether combining noninvasive scoring systems with serum ferritin analysis increases the accuracy of diagnosis of advanced liver fibrosis. METHODS: We performed a retrospective analysis of data from 1014 patients with liver biopsy-confirmed NAFLD. Three cut-points of serum ferritin level, adjusted for sex, were established based on receiver operating characteristics curve analysis: 1.0 (the upper limit of normal [ULN]), 1.5-fold ULN, and 2.0-fold ULN. Three multiple logistic regression models were created to determine the association of these cutoff values with liver fibrosis, adjusting for age, sex, race, diabetes, body mass index, and level of alanine aminotransferase. RESULTS: A greater proportion of patients with increased serum levels of ferritin had definitive NASH and more-advanced fibrosis than patients without increased levels. In all models, serum level of ferritin was significantly associated with the presence and severity of liver fibrosis. However, for all 3 cutoff values, area under the receiver operating characteristic curve values were low (less than 0.60) for the presence of fibrosis or any stage of liver fibrosis; ferritin level identified patients with fibrosis with 16%–41% sensitivity and 70%–92% specificity. The accuracy with which noninvasive scoring systems identified patients with advanced fibrosis did not change with inclusion of serum ferritin values. CONCLUSIONS: Although serum levels of ferritin correlate with more-severe liver fibrosis, based on adjusted multiple logistic regression analysis, serum ferritin levels alone have a low level of diagnostic accuracy for the presence or severity of liver fibrosis in patients with NAFLD

    Modifying one’s hand’s trajectory when a moving target’s orientation changes

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    The path that the hand takes to intercept an elongated moving target depends on the target’s orientation. How quickly do people respond to changes in the moving target’s orientation? In the present study, participants were asked to intercept moving targets that sometimes abruptly changed orientation shortly after they started moving. It took the participants slightly more than 150 ms to adjust their hands’ paths to a change in target orientation. This is about 50 ms longer than it took them to respond to a 5-mm jump in the moving target’s position. It is only slightly shorter than it took them to initiate the movement. We propose that responses to changes in visually perceived orientation are not exceptionally fast, because there is no relationship between target orientation and direction of hand movement that is sufficiently general in everyday life for one to risk making an inappropriate response in order to respond faster

    Early respiratory viral infections in infants with cystic fibrosis

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    This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Background Viral infections contribute to morbidity in cystic fibrosis (CF), but the impact of respiratory viruses on the development of airway disease is poorly understood. Methods Infants with CF identified by newborn screening were enrolled prior to 4 months of age to participate in a prospective observational study at 4 centers. Clinical data were collected at clinic visits and weekly phone calls. Multiplex PCR assays were performed on nasopharyngeal swabs to detect respiratory viruses during routine visits and when symptomatic. Participants underwent bronchoscopy with bronchoalveolar lavage (BAL) and a subset underwent pulmonary function testing. We present findings through 8.5 months of life. Results Seventy infants were enrolled, mean age 3.1 ± 0.8 months. Rhinovirus was the most prevalent virus (66%), followed by parainfluenza (19%), and coronavirus (16%). Participants had a median of 1.5 viral positive swabs (range 0–10). Past viral infection was associated with elevated neutrophil concentrations and bacterial isolates in BAL fluid, including recovery of classic CF bacterial pathogens. When antibiotics were prescribed for respiratory-related indications, viruses were identified in 52% of those instances. Conclusions Early viral infections were associated with greater neutrophilic inflammation and bacterial pathogens. Early viral infections appear to contribute to initiation of lower airway inflammation in infants with CF. Antibiotics were commonly prescribed in the setting of a viral infection. Future investigations examining longitudinal relationships between viral infections, airway microbiome, and antibiotic use will allow us to elucidate the interplay between these factors in young children with CF
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