1,099 research outputs found
Fast Simulation of 2.5D LWD Resistivity Tools
As a first step towards the fast inversion of geophysical data, in this work we focus on the rapid simulations of 2.5D logging-while-drilling (LWD) borehole resistivity measurements. Given a commercial logging instrument configuration, we calibrate the FE method offline with respect to (i) the element sizes via non-uniform tensor product grids; (ii) the arbitrary polynomial order of
approximation on each element; and (iii) the interpolation of certain Fourier modes. This leads to the design of proper FE discretizations to simulate measurements acquired in an arbitrary 2D formation.Numerical results show that we accurately simulate on a sequential computer any field component at a rate faster than one second per logging position.The Marie Sklodowska-Curie grant agreement No 644602
MTM2013-40824-P
SEV-2013-0323
BERC 2014-201
Goal-Oriented p-Adaptivity using Unconventional Error Representations for a 1D Steady State Convection-Diffusion Problem
This work proposes the use of an alternative error representation for Goal-Oriented Adaptivity (GOA) in context of steady state convection dominated diffusion problems. It introduces an arbitrary operator for the computation of the error of an alternative dual problem. From the new representation, we derive element-wise estimators to drive the adaptive algorithm. The method is applied to a one dimensional (1D) steady state convection dominated diffusion problem with homogeneous Dirichlet boundary conditions. This problem exhibits a boundary layer that produces a loss of numerical stability. The new error representation delivers sharper error bounds. When applied to a -GOA Finite Element Method (FEM), the alternative error representation captures earlier the boundary layer, despite the existing spurious numerical oscillations.Basque Government Consolidated Research Group Grant IT649-13
Spanish Ministry under Grant No. FPDI- 2013-17098
ICERMAR Project KK-2015/0000097
CYTED 2011 project 712RT0449
FONDECYT project 116077
Source time reversal (STR) method for linear elasticity
We study the problem of source reconstruction for a linear elasticity problem applied to seismicity induced by mining. We assume the source is written as a variable separable function . We first present a simple proof a local decay result for elasticity in the case of homogeneous media. We then extend the source time reversal method, originally developed for acoustic waves, to an elastic system of waves. Additionally, we present a fast reconstruction implementation for large data sets. This is especially useful in the elastic case, in which the numerical cost is higher than in fluid acoustics. We complement this work with several 2D and 3D numerical experiments and an analysis of the resultsThis work was partially supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant No 644602 GEAGAM (Spain) and CONICYT, Chile - PIA/Concurso de Apoyo a Centros Científicos y Tecnológicos de Excelencia con Financiamiento Basal AFB170001. Additionally, the first author was supported by CONICYT Doctoral fellowship number (Chile), Fondecyt11161033 (Chile), ICMP09-015-F (Chile), and EQM140119. Jaime H. Ortega was partially supported by Fondecyt1111012 and 1171854 (Chile). Ángel Rodríguez-Rozas and David Pardo were partially funded by the Projects of the Spanish Ministry of Economy and Competitiveness with reference MTM2016-76329-R (AEI/FEDER, EU) and MTM2016-81697-ERC/AEI, the BCAM “Severo Ochoa” accreditation of excellence SEV-2017-0718, the Basque Government through the BERC 2018-2021 program, the Consolidated Research Group Grant IT649-13 on “Mathematical Modeling, Simulation, and Industrial Applications (M2SI)”. David Pardo has also received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 777778
Goal-oriented adaptivity using unconventional error representations for the multi-dimensional Helmholtz equation
In goal‐oriented adaptivity, the error in the quantity of interest is represented using the error functions of the direct and adjoint problems. This error representation is subsequently bounded above by element‐wise error indicators that are used to drive optimal refinements. In this work, we propose to replace, in the error representation, the adjoint problem by an alternative operator. The main advantage of the proposed approach is that, when judiciously selecting such alternative operator, the corresponding upper bound of the error representation becomes sharper, leading to a more efficient goal‐oriented adaptivity.
While the method can be applied to a variety of problems, we focus here on two‐ and three‐dimensional (2‐D and 3‐D) Helmholtz problems. We show via extensive numerical experimentation that the upper bounds provided by the alternative error representations are sharper than the classical ones and lead to a more robust p‐adaptive process. We also provide guidelines for finding operators delivering sharp error representation upper bounds. We further extend the results to a convection‐dominated diffusion problem as well as to problems with discontinuous material coefficients. Finally, we consider a sonic logging‐while‐drilling problem to illustrate the applicability of the proposed method.V. Darrigrand, A. Rodriguez-Rozas and D. Pardo were partially funded by the Projects of the Spanish Ministry of Economy and Competitiveness with reference MTM2013-40824-P, MTM2016-76329-R (AEI/FEDER, EU), MTM2016-81697-ERC and the Basque Government Consolidated Research Group Grant IT649- 13 on “Mathematical Modeling, Simulation, and Industrial Applications (M2SI)”. A. Rodriguez-Rozas and D.Pardo were also partially funded by the BCAM “Severo Ochoa” accreditation of excellence SEV-2013-0323 and the Basque Government through the BERC2014-2017 program. A. Rodriguez-Rozas acknowledges support from Spanish Ministry under Grant No. FPDI- 2013-17098. I. Muga was partially funded by the FONDECYT project 1160774. The first four authors were also partially funded by the European Union’s Horizon 2020, research and innovation program under the Marie Sklodowska-Curie grant agreement No 644202. Serge Prudhomme is grateful for the support by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada
A numerical 1.5D method for the rapid simulation of geophysical resistivity measurements
In some geological formations, borehole resistivity measurements can be simulated using a sequence of 1D models. By considering a 1D layered media, we can reduce the dimensionality of the problem from 3D to 1.5D via a Hankel transform. The resulting formulation is often solved via a semi-analytic method, mainly due to its high performance. However, semi-analytic methods have important limitations such as, for example, their inability to model piecewise linear variations on the resistivity. Herein, we develop a multi-scale finite element method (FEM) to solve the secondary field formulation. This numerical scheme overcomes the limitations of semi-analytic methods while still delivering high performance. We illustrate the performance of the method with numerical synthetic examples based on two symmetric logging-while-drilling (LWD) induction devices operating at 2 MHz and 500 KHz, respectively
Combined effects of spray‐drying conditions and postdrying storage time and temperature on Salmonella choleraesuis and Salmonella typhimurium survival when inoculated in liquid porcine plasma
The objective of this study was to determine the effectiveness of the spray-drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray-dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray-drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray-drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray-dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray-drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.info:eu-repo/semantics/publishedVersio
Real world patient-reported outcomes in HIV-infected adults switching to EVIPLERA®, because of a previous intolerance to cART. PRO-STR study
To investigate the impact of switching from stable Combined Antiretroviral Therapy (cART) to single-tablet regimen (RPV/FTC/TDF=EVIPLERA®/COMPLERA®) on patient-reported outcomes in HIV-infected adults who cannot tolerate previous cART, in a real-world setting. PRO-STR is a 48-week observational, prospective, multicenter study. Presence and magnitude of symptoms (main endpoint), health-related quality-of-life (HRQoL), adherence, satisfaction with treatment and patient preferences were assessed. Three hundred patients with 48-week follow-up, who switched to EVIPLERA® (mean age: 46.6 years; male: 74.0%; 74.7% switched from a non-nucleoside reverse-transcriptase-inhibitor, 25.3% from a protease inhibitor + ritonavir) were included. There was no statistical difference in median CD4+ cell count (baseline: 678.5 cells/mm; 48-week: 683.0 cells/mm) neither in virological suppression (≤50 copies/mL) (baseline: 98.3%; 48-week: 95.3%). The most frequent reasons for switching were neuropsychiatric (62.3%), gastrointestinal (19.3%) and biochemical/metabolic (19.3%) events. Only 7.7% of patients permanently discontinued therapy. At 48-week, all outcomes showed an improvement compared to baseline. Overall, there was a significant decrease (p-value≤0.05) in number and magnitude of symptoms, while HRQoL, satisfaction and adherence improved significantly. Most patients prefered EVIPLERA® than previous cART. According to the type of intolerance, HRQoL was improved, but only significantly in patients with neuropsychiatric and gastrointestinal symptoms. Adherence improved significantly in patients with metabolic disturbances and satisfaction with EVIPLERA® was higher in the three groups. Switching to EVIPLERA® from non-nucleoside reverse-transcriptase-inhibitor or protease inhibitor-based regimens due to toxicity, improved the presence/magnitude of symptoms, HRQoL, and preference with treatment. EVIPLERA® maintained a virological response, CD4+ cell count and maintained or improved adherence
Evaluation of ultraviolet‐C and spray‐drying processes as two independent inactivation steps on enterotoxigenic Escherichia coli K88 and K99 strains inoculated in fresh unconcentrated porcine plasma
The objectives of this study were to assess the effectiveness of an ultraviolet (UV‐C, 254 nm) irradiation system and the spray‐drying method as two independent safety steps on inactivation of Escherichia coli K88 and K99 spiked in porcine plasma at 6·46 ± 0·04 log10 ml−1 and 6·78 ± 0·67 log10 ml−1 respectively for UV‐C method, and at 7·31 ± 0·39 log10 ml−1 and 7·66 ± 0·11 log10 ml−1, respectively for the spray‐drying method. The UV‐C method was performed at different UV light doses (from 750 to 9000 J l−1) using a pilot plant UV‐C device working under turbulent flow. Spray‐drying treatment was done at inlet temperature 220 ± 1°C and two different outlet temperatures, 80 ± 1°C or 70 ± 1°C. Results indicated that UV‐C treatment induced a 4 log10 viability reduction for both E. coli at 3000 J l−1. Full inactivation of both E. coli strains was achieved in all spray‐dried samples dehydrated at both outlet temperatures. The special UV‐C system design for turbid liquid porcine plasma is a novel treatment that can provide an additional redundant biosafety feature that can be incorporated into the manufacturing process for spray‐dried animal plasma.info:eu-repo/semantics/publishedVersio
Características clínicas del estado epiléptico en niños de un hospital de tercer nivel de Lima.
Status Epilepticus (SE) in children exhibits high levels of morbidity and mortality and has been poorly studied in Perú. Objective: To describe the frequency and clinical characteristics of children with Status Epilepticus treated at Cayetano Heredia Hospital in Lima. Material and Methods: Retrospective and observational study, case series type, in children under 14 years of age, with Status Epilepticus treated between January and December of 2021. Results: SE was recorded in 28.8% of children with epileptic seizures seen during 2021. Twenty-three children presenting 46 SEs were included. The median age was 2 years, the majority (73,9%) being males, with diagnosis of epilepsy or brain malformation (21.7%) and treated in the pediatric emergency (91%). The predominant semiological pattern was of generalized motor type (52.2%), with remote symptomatic etiology (73.9%), and EEG recorded in a 63% of all cases, mainly reported as normal (75,9%). The median duration was 22 minutes of total resolution, 7 minutes, and of partial resolution, 2 minutes. Midazolam was used as the first line of treatment (78%), and phenytoin as the second line (85%). Conclusions: SE was a frequent condition observed in children throughout the year 2021. Most affected children were male, the predominant etiology was remote symptomatic, and the most common semiological type was the generalized motor. The children were treated according to international management guidelines. A systematic epidemiological surveillance approach is highly encouraged.El estado epiléptico (EE) en niños exhibe altos niveles de morbi-mortalidad y ha sido poco estudiado en el Perú. Objetivo: Describir la frecuencia y características clínicas de niños con estado epiléptico, atendidos en el Hospital Cayetano Heredia de Lima. Material y métodos: Estudio retrospectivo y observacional, tipo serie de casos de niños menores de 14 años con diagnóstico de estado epiléptico, atendidos entre enero y diciembre de 2021. Resultados: Se registró EE en un 28,8% de todos los niños atendidos por crisis epilépticas durante el año 2021. Se incluyeron 23 niños que presentaron 46 EE, varones (73,9%), con una mediana de la edad de 2 años, diagnóstico subyacente de epilepsia o malformación cerebral (21,7%), atendidos en emergencia pediátrica (91%). El tipo semiológico predominante fue el EE motor generalizado (52,2%), con etiología sintomática remota (87%) y EEG registrado en un 63% de los casos, predominantemente de tipo normal (75,9%). La mediana de duración fue de 22 minutos, de resolución total, 7 minutos y resolución parcial, 2 minutos. Se empleó midazolam (78%) como primera línea de tratamiento y fenitoína (85%), como segunda línea. Conclusiones: El EE en niños fue una emergencia prevalente durante el año 2021. La mayoría fueron varones, cuya etiología predominante fue sintomática remota y el tipo semiológico más común fue el motor generalizado. Los niños fueron atendidos de acuerdo con las guías internacionales de manejo. Se insiste en la necesidad de un sistemático afronte de vigilancia epidemiológica
Scientific and local ecological knowledge, shaping perceptions towards protected areas and related ecosystem services
Context Most protected areas are managed based on objectives related to scientific ecological knowledge of species and ecosystems. However, a core principle of sustainability science is that understanding and including local ecological knowledge, perceptions of ecosystem service provision and landscape vulnerability will improve sustainability and resilience of social-ecological systems. Here, we take up these assumptions in the context of protected areas to provide insight on the effectiveness of nature protection goals, particularly in highly human-influenced landscapes. Objectives We examined how residents' ecological knowledge systems, comprised of both local and scientific, mediated the relationship between their characteristics and a set of variables that represented perceptions of ecosystem services, landscape change, human-nature relationships, and impacts. Methods We administered a face-to-face survey to local residents in the Sierra de Guadarrama protected areas, Spain. We used bi- and multi-variate analysis, including partial least squares path modeling to test our hypotheses. Results Ecological knowledge systems were highly correlated and were instrumental in predicting perceptions of water-related ecosystem services, landscape change, increasing outdoors activities, and human-nature relationships. Engagement with nature, socio-demographics, trip characteristics, and a rural-urban gradient explained a high degree of variation in ecological knowledge. Bundles of perceived ecosystem services and impacts, in relation to ecological knowledge, emerged as social representation on how residents relate to, understand, and perceive landscapes. Conclusions Our findings provide insight into the interactions between ecological knowledge systems and their role in shaping perceptions of local communities about protected areas. These results are expected to inform protected area management and landscape sustainability.Peer reviewe
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