Geothermal systems simulation: A case study

Geothermal reservoir simulation is a key step for developing sustainable and efficient strategies for the exploitation of geothermal resources. It is applied in the assessment of several areas of reservoir engineering, such as reservoir performance and re-injection programs, pressure decline in depletion, phase transition conditions, and natural evolution of hydrothermal convection systems. Fluid flow and heat transfer in rock masses, fluid-rock chemical interaction and rock mass deformation are some of the processes addressed in reservoir modelling. The case study of the Las Tres Virgenes (LTV) geothermal field (10 MWe), Baja California Sur, Mexico is presented. Three dimensional (3D) natural state simulations were carried out from emplacement and cooling of two spherical magma chambers using a conductive approach. A conceptual model of the volcanic system was developed on a lithostratigraphic and geochronological basis. Magma chamber volumes were established from eruptive volumes estimations. The thermophysical properties of the medium were assumed to correspond to the dominant rock in each lithological unit as an initial value, and further calibration was made considering histograms of experimentally obtained thermophysical properties of rocks. As the boundaries of the model lie far from the thermal anomaly, we assumed specified temperature boundaries. A Finite Volume (FV) numerical scheme was implemented in a Fortran 90 code to solve the heat equation. Static formation temperatures from well logs were used for validation of the numerical results. Good agreement was observed in those geothermal wells dominated by conductive heat transfer. For other wells, however, it is clear that conduction alone cannot explain observed behaviour, three-dimensional convective models are being implemented for future multiphysics simulations

Mometasone or Tiotropium in Mild Asthma with a Low Sputum Eosinophil Level

Background: In many patients with mild, persistent asthma, the percentage of eosinophils in sputum is less than 2% (low eosinophil level). The appropriate treatment for these patients is unknown. Methods In this 42-week, double-blind, crossover trial, we assigned 295 patients who were at least 12 years of age and who had mild, persistent asthma to receive mometasone (an inhaled glucocorticoid), tiotropium (a long-acting muscarinic antagonist), or placebo. The patients were categorized according to the sputum eosinophil level (= 2%). The primary outcome was the response to mometasone as compared with placebo and to tiotropium as compared with placebo among patients with a low sputum eosinophil level who had a prespecified differential response to one of the trial agents. The response was determined according to a hierarchical composite outcome that incorporated treatment failure, asthma control days, and the forced expiratory volume in 1 second; a two-sided P value of less than 0.025 denoted statistical significance. A secondary outcome was a comparison of results in patients with a high sputum eosinophil level and those with a low level. Results: A total of 73% of the patients had a low eosinophil level; of these patients, 59% had a differential response to a trial agent. However, there was no significant difference in the response to mometasone or tiotropium, as compared with placebo. Among the patients with a low eosinophil level who had a differential treatment response, 57% (95% confidence interval [CI], 48 to 66) had a better response to mometasone, and 43% (95% CI, 34 to 52) had a better response to placebo (P=0.14). In contrast 60% (95% CI, 51 to 68) had a better response to tiotropium, whereas 40% (95% CI, 32 to 49) had a better response to placebo (P=0.029). Among patients with a high eosinophil level, the response to mometasone was significantly better than the response to placebo (74% vs. 26%) but the response to tiotropium was not (57% vs. 43%). Conclusions: The majority of patients with mild, persistent asthma had a low sputum eosinophil level and had no significant difference in their response to either mometasone or tiotropium as compared with placebo. These data provide equipoise for a clinically directive trial to compare an inhaled glucocorticoid with other treatments in patients with a low eosinophil level. (Funded by the National Heart, Lung, and Blood Institute; SIENA ClinicalTrials.gov number, .) In this trial involving patients with mild, persistent asthma, there was no significant difference in therapeutic effect between an inhaled glucocorticoid (mometasone) and placebo in patients with a low sputum eosinophil level (<2%), which was reported in nearly three quarters of the patients.National Heart, Lung, and Blood Institute6 month embargo; published online: 19 May 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Numerical modeling of multiple steady-state convective modes in a tilted porous medium heated from below

Numerical simulations are carried out to determine the steady-state convective modes in a rectangular porous cavity heated from below. The property of multiplicity of solutions for a given set of governing parameters is examined in this paper. The multiple steady-state solutions that appear in a horizontal cavity for a given Rayleigh number are obtained by means of suitable initial conditions. Each of these solutions is then perturbed by increasing the inclination angle in order to identify the transition angle to a different convective mode. It is observed that for an odd-number of convective cells, if the counterclockwise rotating cells dominate the configuration, the Nusselt number increases with the slope angle up to a maximum and then decreases before the transition to single cell convection. Otherwise, if there are more clockwise rotating cells, the Nusselt number decreases monotonically and the configuration becomes unstable. Since multicellular configurations with even number of convective cells have equal number of clockwise and counterclockwise rotating cells, this case presents a single behavior characterized by a decrease in the Nusselt number. The transition angles from multicellular to single cell convection are found to be as large as 45° when the aspect ratio of the cavity is large, so that this angle is the upper limit to destabilize multicellular convection

Clostridium difficile outbreaks: Prevention and treatment strategies

The incidence and severity of Clostridium difficile infection (CDI) have increased dramatically over the past decade. Its treatment, however, has largely remained the same with the exception of oral vancomycin use as a first-line agent in severe disease. From 1999 to 2004, 20,642 deaths were attributed to CDI in the United States, almost 7 times the rate of all other intestinal infections combined. Worldwide, several major CDI outbreaks have occurred, and many of these were associated with the NAP1 strain. This ‘epidemic’ strain has contributed to the rising incidence and mortality of CDI. The purpose of this article is to review the current management, treatment, infection control, and prevention strategies that are needed to combat this increasingly morbid disease

Role of the extended lymphadenectomy in gastric cancer surgery: experience

Although curative resection is the treatment of choice for gastric cancer, controversy exists about the adequate extent of lymph node dissection when resection is performed. METHODS: We retrospectively assessed 85 patients who underwent a limited lymphadenectomy (D1) and 71 who had an extended lymph node dissection (D2) in a single institution between 1990 and 1998 (median follow-up, 37.3 months). Prognostic factors were assessed by Cox proportional hazard models adjusted for potential confounders. RESULTS: We found no significant difference in the length of hospital stay (median, 12.1 and 13.1 days), overall morbidity (48.2% and 53.5%), or operative mortality (2.3% and 0%) between D1 and D2, respectively. Five-year survival in the D2 group was longer (50.6%) than in the D1 group (41.4%) for tumor stages (tumor-node-metastasis) >I. In multivariate analysis, tumor-node-metastasis stage (hazard ratio for stages >I vs. 0-I, 11.6), the ratio between invaded and removed lymph nodes, the presence of distant metastases, Lauren classification, and the extent of lymphadenectomy (hazard ratio for D1 vs. D2, 2.3; 95% confidence interval, 1.25-4.30) were the only significant prognostic factors. CONCLUSIONS: Our experience shows that extended (D2) lymph node dissection improves survival in patients with resected gastric cancer

Focusing on outcomes: Making the most of COPD interventions

A number of excellent intervention studies related to clinical and psychosocial aspects of chronic obstructive pulmonary disease (COPD) have been undertaken in the recent past. A range of outcomes have been examined including pulmonary function, health care use, quality of life, anxiety and depression, ambulation, exercise capacity, and self-efficacy. The purpose of this narrative review was to a) consider clinical, psychosocial, and educational interventions for people living with COPD in light of the health related outcomes that they have produced, b) identify the type of interventions most associated with outcomes, c) examine work related to COPD interventions as it has evolved regarding theory and models compared to work in asthma, and d) explore implications for future COPD research. Studies reviewed comprised large scale comprehensive reviews including randomized clinical trials and meta-analysis as these forms of investigation engender the greatest confidence in clinicians and health care researchers. Extant research suggests that the most significant improvements in COPD health care utilization have been realized from interventions specifically designed to enhance disease management by patients. A range of interventions have produced modest changes in quality of life. Evidence of impact for other outcomes and for a particular type of intervention is not strong. Research in other chronic diseases, particularly asthma, suggests that interventions grounded in learning theory and models of behavior change can consistently produce desired results for patients and clinicians. Use of a model of self-regulation may enhance COPD interventions. Although the extent to which COPD efforts can benefit from the experience in other conditions is a question, more outcome focused intervention studies using more robust theoretical approaches may enhance COPD results, especially regarding health care use and quality of life

Wersync: A WEB-BASED PLATFORM FOR DISTRIBUTED MEDIA SYNCHRONIZATION AND SOCIAL INTERACTION

This paper presents Wersync, which is an adaptive and accurate web-based platform that enables distributed media synchronization and social interaction across remote users. By using Wersync, users can create or join on-going sessions for concurrently consuming the same media content with other remote users in a synchronized manner. Besides, social interaction is provided by sharing the navigation control commands and by integrating synchronized text chat channels. Additionally, two social presence mechanisms have been added to stimulate the participation of external users in on-going sessions on Wersync. By exclusively relying on standard web-based technologies, this platform can guarantee cross-network, cross-platform and crossdevice support, which is a key point in the current heterogeneous media delivery ecosystem

De la biografía a la prosopografía: los parlamentarios de los distritos de Vasconia en la II República española (1931-1939)

Having carried out a micro-biographical analysis, using primary sources, of the 610 parliamentarians who represented the Basque districts between 1808 and 1939 in successive biographical dictionaries, we now undertake a prosopographical analysis of 44 parliamentarians who represented the districts of the Basque Country in the Spanish II Republic (1931-1939). Aspects covered include: geographical origin, age, life expectancy, educational and professional profile, cultural level and sociability, continuity in political activity between the Monarchy and the Republic. The work offers novel comparative conclusions.Realizado un análisis microbiográfico, con fuentes primarias, de los 610 parlamentarios que representaron a los distritos vascos entre 1808 y 1939 en sucesivos diccionarios biográficos, abordamos el análisis prosopográfico de los 44 parlamentarios que representaron a los distritos de Vasconia en la II República española (1931-1939): origen geográfico, edad, esperanza de vida, perfil educativo y profesional, nivel cultural y sociabilidad, continuidad en la actividad política entre la Monarquía y la República. El trabajo ofrece conclusiones comparativas novedosas