444 research outputs found

    Use of Novel Spatial Presentations of Plant Species to Improve Legume Abundance

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    The benefits of using white clover (Trifolium repens) in pasture grazed by sheep have been widely recognised. However, clover is considered inadequate and risky as the main source of nitrogen input, since its abundance in the pasture is patchy, low (typically less than 20%) and shows great year-to-year variation. This is thought to be due to the costs of nitrogen fixation, competition with grass, the preference for clover by sheep and patchy dung and urine deposition (Schwinning & Parsons, 1996). One possible solution may be the spatial separation of clover from grass, which would remove inter-specific competition, allowing clover to grow unimpeded in a greater abundance than previously observed. Spatial separation can occur over a range of spatial scales, from narrow strips of alternating clover and grass to complete separation, where half a pasture is clover while the other half is grass. This in turn may have a significant impact on the processes occurring within the pasture, such as plant growth and spread, nitrogen cycling and animal behaviour

    Optimización estructural y operativa de sistemas de evaporación

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    En este trabajo se estudia la optimización simultánea de la estructura y la planificación operativa y de mantenimiento (por limpieza) de sistemas de evaporación con múltiples unidades, teniéndose en cuenta el efecto del ensuciamiento de los equipos, utilizando programación matemática. Como estrategia de optimización se utilizó el concepto de ciclo de operación y limpieza, que debe ser repetido tantas veces como sea necesario para alcanzar la producción de planta requerida. El modelo matemático de optimización desarrollado utiliza variables continuas y binarias por lo que resulta de tipo no lineal mezcla entera (MINLP). Se presentan resultados de la comparación de un caso práctico correspondiente a un ingenio azucarero, con la solución óptima resultante del modelo, mostrando una reducción del orden del 2 % en términos de costo anual equivalente y del 5,5 % los costos horarios.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Optimización estructural y operativa de sistemas de evaporación

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    En este trabajo se estudia la optimización simultánea de la estructura y la planificación operativa y de mantenimiento (por limpieza) de sistemas de evaporación con múltiples unidades, teniéndose en cuenta el efecto del ensuciamiento de los equipos, utilizando programación matemática. Como estrategia de optimización se utilizó el concepto de ciclo de operación y limpieza, que debe ser repetido tantas veces como sea necesario para alcanzar la producción de planta requerida. El modelo matemático de optimización desarrollado utiliza variables continuas y binarias por lo que resulta de tipo no lineal mezcla entera (MINLP). Se presentan resultados de la comparación de un caso práctico correspondiente a un ingenio azucarero, con la solución óptima resultante del modelo, mostrando una reducción del orden del 2 % en términos de costo anual equivalente y del 5,5 % los costos horarios.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Pitfalls of Teachers on Modular Distance Learning: Basis for a Proposed Action Plan

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    The study was conducted to determine the pitfalls encountered by grade five teachers during modular teaching and learning. Specifically, it aimed to find out the pitfalls encountered by teachers along with students’ comprehension, students’ academic behavior, monitoring of students’ education, and physical interaction with the learners. The personal profile of teachers, out of the total respondents (56), most of the teachers are female-dominated. Most of them belong to the age bracket of 34 to 45 and most of the teachers are married. Most of the teachers had attended post-graduate studies. Most respondents are still young in the service, holding Teacher 2 and Teacher 3 positions, and attending local, national, and regional training. On the level of pitfalls encountered by teachers in modular teaching and learning, most respondents experienced a slight gravity level in the four aspects. The computed average weighted mean along comprehension is 2.50, along academic behavior is 2.54, along monitoring of students’ performance is 2.58, and along physical interaction is 2.79. All have an equivalent value of moderately grave. There is a specific profile of teachers that is significantly related. Age is significantly associated with monitoring students’ learning. The computed r value is .270, while the calculated significance level is 0.04. Training attended by the teachers is significantly related to some aspects of students’ comprehension, (computed sig. value is 0.04 and physical interaction is .02), which is lower than the .05 level of significance. The grade five teachers who served as respondents are mostly female dominated; they are in their early forties and married. Most of them are attending post-graduate studies and have attended relevant training. Second, the level of teachers’ pitfalls is mostly moderately grave. In addition, age is significantly related to monitoring, training is significantly associated substantially with physical interaction and comprehension

    Optimización estructural y operativa de sistemas de evaporación

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    En este trabajo se estudia la optimización simultánea de la estructura y la planificación operativa y de mantenimiento (por limpieza) de sistemas de evaporación con múltiples unidades, teniéndose en cuenta el efecto del ensuciamiento de los equipos, utilizando programación matemática. Como estrategia de optimización se utilizó el concepto de ciclo de operación y limpieza, que debe ser repetido tantas veces como sea necesario para alcanzar la producción de planta requerida. El modelo matemático de optimización desarrollado utiliza variables continuas y binarias por lo que resulta de tipo no lineal mezcla entera (MINLP). Se presentan resultados de la comparación de un caso práctico correspondiente a un ingenio azucarero, con la solución óptima resultante del modelo, mostrando una reducción del orden del 2 % en términos de costo anual equivalente y del 5,5 % los costos horarios.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Understanding disease control: influence of epidemiological and economic factors

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    We present a local spread model of disease transmission on a regular network and compare different control options ranging from treating the whole population to local control in a well-defined neighborhood of an infectious individual. Comparison is based on a total cost of epidemic, including cost of palliative treatment of ill individuals and preventive cost aimed at vaccination or culling of susceptible individuals. Disease is characterized by pre- symptomatic phase which makes detection and control difficult. Three general strategies emerge, global preventive treatment, local treatment within a neighborhood of certain size and only palliative treatment with no prevention. The choice between the strategies depends on relative costs of palliative and preventive treatment. The details of the local strategy and in particular the size of the optimal treatment neighborhood weakly depends on disease infectivity but strongly depends on other epidemiological factors. The required extend of prevention is proportional to the size of the infection neighborhood, but this relationship depends on time till detection and time till treatment in a non-nonlinear (power) law. In addition, we show that the optimal size of control neighborhood is highly sensitive to the relative cost, particularly for inefficient detection and control application. These results have important consequences for design of prevention strategies aiming at emerging diseases for which parameters are not known in advance

    Improving animal welfare using continuous nalbuphine infusion in a long-term rat model of sepsis

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    Abstract Background Sepsis research relies on animal models to investigate the mechanisms of the dysregulated host response to infection. Animal welfare concerns request the use of potent analgesics for the Refinement of existing sepsis models, according to the 3Rs principle. Nevertheless, adequate analgesia is often missing, partly because the effects of analgesics in this particular condition are unknown. We evaluated the use of nalbuphine, an opioid with kappa agonistic and mu antagonistic effects, in rats with and without experimental sepsis. Methods Male Wistar rats were anesthetized with isoflurane and instrumented with a venous line for drug administration. Arterial cannulation allowed for blood pressure measurements and blood sampling in short-term experiments of non-septic animals. Nalbuphine (or placebo) was administered intravenously at a dose of 1 mg/kg/h. Long-term (48 h) experiments in awake septic animals included repetitive clinical scoring with the Rat Grimace Scale and continuous heart rate monitoring by telemetry. Sepsis was induced by intraperitoneal injection of faecal slurry. Nalbuphine plasma levels were measured by liquid chromatography—high resolution mass spectrometry. Results In anesthetized healthy animals, nalbuphine led to a significant reduction of respiratory rate, heart rate, and mean arterial pressure during short-term experiments. In awake septic animals, a continuous nalbuphine infusion did not affect heart rate but significantly improved the values of the Rat Grimace Scale. Nalbuphine plasma concentrations remained stable between 4 and 24 h of continuous infusion in septic rats. Conclusions In anaesthetised rats, nalbuphine depresses respiratory rate, heart rate, and blood pressure. In awake animals, nalbuphine analgesia improves animal welfare during sepsis

    Repositionable Versus Balloon-Expandable Devices for Transcatheter Aortic Valve Implantation in Patients With Aortic Stenosis.

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    The safety and effectiveness of the fully repositionable LOTUS valve system as compared with the balloon-expandable Edwards SAPIEN 3 prosthesis for the treatment of aortic stenosis has not been evaluated to date. All patients undergoing transcatheter aortic valve implantation with the Edwards SAPIEN 3 or the LOTUS valve system were included into the Swiss Transcatheter Aortic Valve Implantation Registry. An adjusted analysis was performed to compare the early clinical safety outcome according to the Valve Academic Research Consortium-2 definition. Between February 2014 and September 2015, 140 and 815 patients were treated with the LOTUS and the Edwards SAPIEN 3 valve, respectively. There was no difference in crude and adjusted analyses of the early safety outcome between patients treated with LOTUS (14.3%) and those treated with Edwards SAPIEN 3 (14.6%) (crude hazard ratio, 0.97; 95% CI, 0.61-1.56 [P=0.915]; adjusted hazard ratio, 1.03; 95% CI, 0.64-1.67 [P=0.909]). More than mild aortic regurgitation was <2% for both devices. A total of 34.3% of patients treated with LOTUS and 14.1% of patients treated with Edwards SAPIEN 3 required a permanent pacemaker (HR, 2.76; 95% CI, 1.97-3.87 [P<0.001]). The repositionable LOTUS valve system and the balloon-expandable Edwards SAPIEN 3 prosthesis appeared comparable in regard to the Valve Academic Research Consortium-2 early safety outcome, and the rates of more than mild aortic regurgitation were exceedingly low for both devices. The need for new permanent pacemaker implantation was more frequent among patients treated with the LOTUS valve

    Technical and Clinical Outcomes After Transcatheter Edge-to-Edge Repair of Mitral Regurgitation in Male and Female Patients: Is Equality Achieved?

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    Currently, no clear impact of sex on short- and long-term survival following transcatheter edge-to-edge mitral valve repair (TEER) is evident, although no data are available on postprocedural life expectancy. Our aim was to assess sex-specific differences in outcomes of patients with mitral regurgitation (MR) treated by TEER. Short-term and 5-year outcomes in men and women undergoing TEER between 2011 and 2018 who were included in the large, multicenter, real-world MitraSwiss registry were analyzed. Outcomes were compared stratified by sex and according to MR cause (primary versus secondary). The impact of TEER on postprocedural life expectancy was estimated by relative survival analysis. Among 1142 patients aged 60 to 89 years, 39.8% were women. They were older, with fewer cardiovascular risk factors and lower functional capacity compared with men. Thirty-day mortality was higher in men than in women (3.3% versus 1.1%; odds ratio, 3.16 [95% CI, 1.16-10.7]; P=0.020). Five-year survival was comparable in both sexes (adjusted hazard ratio for 5-year mortality in men, 1.14 [95% CI, 0.90-1.44], P=0.275). Both men and women with either primary or secondary MR showed similar clinical efficacy over time. TEER provided high relative survival estimates among all groups, and fully restored predicted life expectancy in women with primary MR (5-year relative survival estimate, 97.4% [95% CI, 85.5-107.0]). TEER is not associated with increased short-term mortality in women, whereas 5-year outcomes are comparable between sexes. Moreover, TEER completely restored normal life expectancy in women with primary MR. A residual excess mortality persists in secondary MR, independently of sex
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