RELACIONES CONCEPTUALES EN EL MODELO ENFERMERO BASADO EN EL MODELO VITAL DE ROPER, LOGAN Y TIERNEY.

For several decades, the nursing discipline has suffered from the adoption of a model belonging to the same discipline. The professional inheritance from a more technical figure has hold up the development of nursing as a science with a capacity of clinical judgment and reasoning. A model needs to be made under a particular perspective of what is the individual, environment, health and the nursing itself. That is to say, taking into account one of the different nursing existing models. The relation between the model and the day-to-day practice has not been clear due to lack of unanimity. The ideal is to assume the daily work inside of a determined clinical domain according to a nursing model. The nursing model based in the vital model of Roper, Logan and Tierney represents a valid model for different working clinical domains. In this article, the different concepts attached to this model and the relations between them and the concepts that relate to the nursing paradigm are discussed.La ciencia enfermera adolece, desde hace varias décadas, de la adopción y asunción de un modelo propio de la disciplina. La herencia profesional desde una figura más técnica ha retrasado el desarrollo de la Enfermería como ciencia con capacidad de juicio y razonamiento clínico. Ello debe hacerse bajo una perspectiva particular de lo que es el individuo, su entorno, la salud y la propia Enfermería. Es decir, bajo la mirada de uno de los diferentes modelos enfermeros existentes. Sus relaciones con la práctica diaria han quedado siempre amputadas por falta de unanimidad. Lo ideal es asumir el trabajo diario, dentro de un ámbito clínico determinado, según un modelo enfermero. El modelo enfermero basado en el modelo vital de Roper, Logan y Tierney es un modelo válido para diferentes ámbitos clínicos de trabajo. En el presente artículo, estudiaremos los diferentes conceptos que integran dicho modelo y las relaciones entre ellos y con los conceptos que integran el paradigma enfermero

The role of microparticles on the shape and surface tension of static bubbles

HYPOTHESIS: Surface tension is a critical parameter in bubbles and foams, yet it is difficult to assess when microparticles are attached at the interface. By considering the interaction force between an air-liquid interface and microparticles, modified equations for sessile bubble tensiometry can be derived to determine the surface tension and shape of static microparticle-laden bubbles. EXPERIMENTS: A modified sessile bubble method, in which the forces between microparticles and the air-liquid interface are considered, was developed and used to analyse the surface tension of bubbles fully coated by a monolayer of silica microparticles of different sizes. The results are compared to those obtained using classical sessile bubble tensiometry. The new method is also used to investigate the contours of particle-laden bubbles of varying particle radius and contact angle. FINDINGS: While the classical sessile bubble method overestimates the surface tension, results obtained using the modified sessile bubble method show that the surface tension of static microparticle-laden bubbles remains the same as that of uncoated bubbles, with no dependency on the particle size. The discrepancy is due to the fact that microparticles attached to the air-liquid interface deform a bubble in a similar way that changes in surface tension do for uncoated bubbles

A framework for polydisperse pulp phase modelling in flotation

Froth flotation is one of the most widely-used mineral processing operations. The pulp zone in flotation tanks is polydisperse in general and serves as a medium for the interaction between the solid particles and the gas bubbles in a liquid continuum, leading to particle–bubble attachment/detachment and bubble coalescence/breakage phenomena. To better predict the hydrodynamics and inform the design of e cient flotation equipment, it is therefore important to accurately model and simulate the evolution of the size distribution of the dispersed phases. This has created an urgent need for a framework that can model the pulp phase in an e cient manner, which is not currently available in the literature. The available software products are not e cient enough to allow for a tractable modelling of industrial-scale flotation cells and in some cases they cannot model the polydispersity of the dispersed phase at all. This work presents an e cient numerical framework for the macroscale simulation of the polydisperse pulp phase in froth flotation in an open-source finite element computational fluid dynamics (CFD) code that provides an e cient solution method using mesh adaptivity and code parallelisation. A (hybrid finite element–control volume) finite element framework for modelling the pulp phase has been presented for the first time in this work. An Eulerian–Eulerian turbulent flow model was implemented in this work including a transport equation for attached and free solid particles. Special care was taken to model the settling velocity of the free solids and the modification of the liquid viscosity due to the presence of these particles. Bubble polydispersity was modelled using the population balance equation (PBE), which was solved using the direct quadrature method of moments (DQMOM). Appropriate functions for bubble coalescence and breakage were chosen in the PBE. Mesh adaptivity was applied to the current problem to produce fully-unstructured anisotropic meshes, which improved the solution e ciency, while all simulations were executed on a multicore architecture. The model was validated for 2D simulations of a bubble column against experimental results available in the literature. After successful validation, the model was applied to the simulation of the pulp phase in a flotation column for monodisperse and polydisperse solids. Polydispersity of the solids was modelled for the first time in this work using three separate solid size classes. A clear dependence of the flotation rate on the particle size was noticed and the monodisperse solids simulations were shown to over-predict the flotation rate. Other than flotation, this open-source framework can be used for the simulation of a variety of polydisperse multiphase flow problems in the process industry

Yield stress of foam flow in porous media: The effect of bubble trapping

Foam behaves as a yield-stress fluid as it flows in a porous medium. Quasi-static analysis suggests that the yield stress arises from the non-smooth motion of foam films, denoted as lamellae, in pores. In order to study the effect of trapped lamellae on the motion of a moving lamella and consequently on the yield stress of foam, we conduct numerical simulations in the quasi-static limit. We propose a new method utilizing the surface energy minimization algorithm, which explicitly considers the connectivity of pores in a porous medium. We consider two different shapes of pore and vary the number of nearby trapped lamellae to investigate the effects of bubble trapping on the non-smooth and the smooth motion of a single lamella passing through a pore, respectively. We find that the trapped lamellae lead to the increased volume-averaged pressure drop and thus the increased yield stress. Notably, the motion of a lamella through a pore with rounded corners in the pore body becomes non-smooth, due to the presence of trapped lamellae. The results contribute to a better understanding of the yield stress of foam in porous media

The selection of renewable energy technologies using a hybrid subjective and objective multiple criteria decision making method

The use of renewable energy technologies is a key factor for sustainable development but their selection from several alternatives is a difficult task that relies on the careful assessment of relevant criteria. While Multiple Criteria Decision Making (MCDM) methods have been used successfully in various renewable energy technology selection problems, the decision process becomes more challenging when preferential judgements are made on the basis of non-homogenous and imprecise input data, and when there is uncertainty due to disparities among decision makers. This paper presents a hybrid MCDM method capable of overcoming these problems by taking into account quantitative and qualitative data under a probabilistic environment in the context of group decision making. In this method, qualitative data is fuzzified and used along with quantitative data to develop a hybrid model. A coefficient factor allows decision makers to vary the weight of each quantitative model so that the resultant criteria weights and overall alternatives’ scores consider both subjective considerations and objective information. An example is presented to showcase the usability of the method developed for ranking and evaluating renewable energy technologies in the mining industry. In addition, the impact of different coefficient factors on the final results was assessed by means of sensitivity analysis. The results indicate that the method developed is able to minimise the loss of valuable objective information, caused by the subjective bias of qualitative weights during the evaluations, by adjusting the coefficient factors of the hybrid model during the calculations

Evaluation of collector performance at the bubble-particle scale

Particle attachment and detachment in froth flotation are complex processes and their measurement presents many challenges. Of particular interest is the effect of collectors at the bubble-particle scale, in order to assess the strength or collecting ability of these reagents. However, studies of the effect of collectors on particle attachment at the bubble-particle scale are scarce. In this work, we propose a methodology to characterise collector strength by measuring the attachment rate of particles to a capillary-pinned bubble. An image processing technique was developed to quantify bubble surface coverage over time, which was then used to determine particle attachment kinetics. The image analysis strategy is based on the sessile drop method and uses curve fitting to determine accurately the particle coverage. The methodology was used to assess the collecting ability of three chalcopyrite collectors. Interestingly, although very similar contact angle measurements were found for two of the collectors, they showed distinctly different particle attachment kinetics. It is proposed that this particle-bubble attachment method can be used to gain additional information not currently available from either contact angle measurements or bulk collector performance tests

Optimising froth stability of copper flotation tailings

Linking results from laboratory scale experiments to industrial flotation behaviour is challenging. Typically, such experiments involve batch tests in which the system does not operate at steady-state, making it difficult to infer the effects that operating conditions have on flotation performance. In order to overcome this limitation a 4-litre recirculating tank was previously developed at Imperial College London. This tank is capable of reaching, and operating at, steady-state by recycling overflowing concentrate back into the feed. As well as instruments to control operating conditions, it is fitted with a system of sensors that allow the surface of the froth to be dynamically monitored. From this information, it is possible to measure the air recovery a proxy for froth stability. Thus, this bench-scale tank can be used to understand the effect of differing operating conditions on flotation performance at steady state. However, so far, this cell has only been used to investigate idealised systems with only one or two species. Reprocessing of tailings dams is not only environmentally desirable but also increasingly economically feasible due to the declining head grades of primary deposits. There is also the added benefit of no further milling being required prior to flotation. However, the effects of fine and ultrafine particles on froth stability are not yet fully understood. In this work, the bench-scale continuous tank has been used for the first time to determine the flotation response of a complex feed, consisting of samples from a copper tailings dam, to changes in operating conditions. It was shown that the froth stability in the system is comparable to that of previous work and industrial tests, with a peak in air recovery being found at a superficial gas velocity of 1.13 cm/s. There is scope to optimise the froth stability of tailings flotation for enhanced metallurgical performance

Factores asociados al incremento en el uso de la metodología enfermera en Atención Primaria

Introduction: Indicators show a sustained increase in the use of nursing methodology (NM) in the Health Complex in Tenerife.Aim: to identify the factors that may be associated with this growth.Methods and materials: Retrospective analytical study. Area of study: patients with a computerised record of health. Subjects of the study numbered 609,688. Data analysis was performed from March 2005 to February 2010. Measurements: these were analysed monthly for each Basic Health Area (BHA) and measured the relative frequency of records with functional health patterns, (PFS), NANDA diagnoses, NOC objectives and NIC interventions. An NM global index was constructed from the mean value of the indicators and growth was calculated over the 60 months studied. Other variables measured included users of nursing consultations; quotas; patient load; non programmed consultations; consultations from other areas; home visits; presence of link nursing in the BHA; training and assessment in ME in the BHA; computer time. Data processing: variables were summarised as median (P5-P95) due to the non normal distribution. The correlation índex-ME growth and each variable was estimated using the Spearman non parametric linear correlation coefficient. Comparisons were made with the Mann-Whitney U test. All tests were significant at 5%.Results: Findings show a greater percentage of health records with ME and greater monthly growth when computerisation in the area was longer; when the percentage of users of nursing consultancies was higher; when the number of home visits was higher; when patient load was greater; when quotas were smaller; when consultations from other areas were lower. There was a higher percentage of medical records with ME and greater monthly growth in BHAs with ME assessment programme and in areas with ECE.Conclusions: Increased use of ME in the BHA in Tenerife is associated to each of the factors considered in different direction and size.Introducción: Se observa un incremento sostenido en los indicadores de empleo de la Metodología enfermera (ME) en el Área de Salud de Tenerife.Objetivo: Identificar los factores que pudieran asociarse a este crecimiento.Material y métodos: Estudio analítico retrospectivo. Ámbito de estudio: Pacientes con historia de salud informatizada. Los sujetos del estudio fueron 609688. El análisis de los datos se llevó a cabo en el periodo temporal marzo de 2005 a febrero de 2010. Mediciones: Se analizaron, para cada Zona Básica de Salud (ZBS) y mensualmente, la frecuencia relativa de historias con Patrones funcionales de salud (PFS), diagnósticos NANDA, objetivos NOC e intervenciones NIC. Se construyó un índice global de ME con el valor medio de estos indicadores y se calculó el crecimiento a lo largo de los 60 meses a estudio. Se midieron también otras variables: utilizadores de consultas de enfermería; volumen del cupo; presión asistencial; consultas fuera de agenda prevista; consultas de otras zonas; visitas a domicilio; presencia de enfermería de enlace (ECE) en la ZBS; formación-asesoramiento en ME en la ZBS; tiempo de informatización. Procesamiento de datos: Las variables se resumieron como mediana (P5-P95) debido a su distribución no normal. La correlación entre índice-crecimiento ME y cada variable se estimó utilizando el coeficiente de correlación lineal no paramétrica de Spearman. Las comparaciones se realizaron con la prueba U de Mann-Whitney. Todas las pruebas a un 5% de significación estadística.Resultados: Se comprobó un mayor porcentaje de historias de salud con ME así como un mayor crecimiento mensual: a mayor tiempo de informatización en la zona; a mayor porcentaje de utilizadores de consultas deenfermería; a mayor número de visitas a domicilio; a mayor presión asistencial; a menor volumen de cupo; a menor porcentaje de consultas de otras zonas. Igualmente se comprobó mayor porcentaje de historias de salud con ME y mayor crecimiento mensual en las ZBS formadas con un programa de asesoramiento en ME así como en las zonas con ECE.Conclusiones: El incremento en el empleo de la ME en las ZBS de Tenerife se asocia a cada uno de los factores considerados, en diferente sentido y magnitud

A methodology to implement a closed-loop feedback-feedforward level control in a laboratory-scale flotation bank using peristaltic pumps

This paper describes the implementation of a level control strategy in a laboratory-scale flotation system. The laboratory-scale system consists of a bank of three flotation tanks connected in series, which mimics a flotation system found in mineral processing plants. Besides the classical feedback control strategy, we have also included a feedforward strategy to better account for process disturbances. Results revealed that the level control performance significantly improves when a feedforward strategy is considered. This methodology uses peristaltic pumps for level control, which has not been extensively documented even though: (1) peristaltic pumps are commonly used in laboratory-scale systems, and (2) the control implementation is not as straightforward as those control strategies that use valves. Therefore, we believe that this paper, which describes a proven methodology that has been validated in an experimental system, can be a useful reference for many researchers in the field.•Preparation of reagents to ensure that the froth stability of the froth layer is representative of an industrial flotation froth.•Calibration of instruments - convert the electrical signal from PLCs to engineering units.•Tuning PI parameters using SIMC rules by performing step-changes in each flotation cell

The link between particle size and froth stability - Implications for reprocessing of flotation tailings

Historic tailings dams can often be considered as valuable mineral reserves due to the declining head grades of primary deposits. The reprocessing of such material is of great interest to the minerals processing industry, not only from an economic point of view, but also from an environmental one. However, tailings material is generally comprised of fine particles, which poses a challenge for its reprocessing using froth flotation due to reduced recoveries of these particle sizes. In addition, there is some debate as to the effect that these fine particles have on the froth stability, which in turn is linked to mineral recovery. In this work, air recovery was used as a measure of froth stability to determine the flotation response of a copper tailings ore to changes in particle size distribution and superficial gas velocity. The system exhibited a maximum in air recovery, which correlates well with the local peak in dynamic froth stability presented in previous work. This maximum in froth stability is also shown to correspond to an improvement in flotation performance, thus highlighting the importance of considering the link between particle size, air rate and froth stability when determining the flotation strategy for tailings reprocessing. The results are discussed in terms of the implications for the reprocessing plant from where the ore samples were obtained and, more generally, for the efficient flotation reprocessing of tailings