Relación de exposición a polvos de carbón, sílice cristalina y neumoconiosis, en trabajadores de minas de socavón, Cundinamarca, 2014.

Objetivo: Determinar el nivel de riesgo de la exposición por fracción respirable a polvo de carbón y sílice cristalina y la prevalencia de neumoconiosis en trabajadores de minas de socavón del departamento de Cundinamarca. Métodos: estudio de corte transversal, en grupos de exposición similar (GES) en las minas seleccionadas, el tamaño muestral fue constituido por 11 empresas y 215 trabajadores en donde se realizó un muestreo ambiental para medir los niveles de polvo de carbón y sílice cristalina. Resultados: La edad promedio del grupo fue de 46±9,5 años y género masculino (97,2%), se encontró una asociación significativa entre polvo de carbón y neumoconiosis (p =0,050) y no fue significativa con exposición a sílice cristalina (p = 0,537). El modelo de regresión logística mostró asociación significativa con la escala de nivel de riesgo de carbón medio (OR=10.4, IC 95%:1.50, 71.41, p=0,02), ajustando con variables significativas como: tamaño de la empresa mediana (OR = 2,67, IC 95%:1.07, 6.66, p=0,04), antigüedad mayor o igual a 30 años (OR = 7,186, IC 95%:2.98, 17.29, p=0,001) y habito tabáquico por más de un año (OR = 4,437, IC 95%:2.06, 9.55, p=0,001) para sílice cristalina no hubo asociación en el modelo multivariado. Conclusión: El riesgo de exposición a carbón de nivel medio está relacionado con la prevalencia de neumoconiosis y otros factores adicionales como tamaño de la empresa mediana, antigüedad mayor o igual a 30 años y habito tabáquico por más de un año para los trabajadores de minería de socavón en Cundinamarca. Para los niveles de sílice cristalina no se encontró asociación significativa.

Prevalencia de patologías osteomusculares del miembro superior y su relación con factores ocupacionales en trabajadores de una empresa de flores. Bogotá 2015

Antecedentes: Las patologías osteomusculares del miembro superior son una importante causa de morbilidad laboral a nivel mundial y en nuestro país, particularmente en el sector de la floricultura. Del desarrollo de estos desórdenes se derivan importantes costos derivados del ausentismo laboral, incapacidades y secuelas. Objetivo: determinar la prevalencia de patología osteomuscular de miembro superior con calificación de origen de enfermedad laboral, en los trabajadores con diagnóstico de patología musculo esquelética de miembro superior y su relación con algunos factores ocupacionales y demográficos. Metodología: Estudio de corte transversal en el que se revisaron datos secundarios procedentes de una base de datos del servicio de salud ocupacional entre enero y mayo de 2015, correspondiente a 465 operarios (no administrativos) a término indefinido de una empresa floricultora de Bogotá, incluyendo únicamente aquellos trabajadores con patologías osteomusculares de miembro superior, que contaban con la clasificación en el diagnóstico ya sea como enfermedad laboral o enfermedad común y mayores de edad. Se excluyeron 19 trabajadores, quienes habían sido reubicados en nuevos sitios de trabajo y no se contó con la información para determinar su actividad antes de realizar el cambio. Se evaluaron las siguientes variables: sexo, edad, antigüedad y el cargo desempeñados por los operarios. La relación entre variables se realizó con la prueba de chi2 de Pearson. Se midió la magnitud de la asociación por medio de OR con sus respectivos intervalos de confianza del 95%. Resultados: Se incluyó a 373 operarios a término fijo, con una media de edad de 39 años (DE=5.55) y una media de antigüedad en el cargo de 6 años (DE=1.15). El 82.84% correspondió al sexo femenino. La prevalencia de enfermedad laboral osteomuscular de miembro superior fue del 54,4%. En el análisis de relación entre la calificación de la enfermedad, y demás variables (sexo, antigüedad en el cargo, edad, actividad desempeñada, localización de la lesión); se encontró que: estar entre los 40 a 49 años (OR= 1,7; IC-95%:1,12 – 2,79), diagnóstico de síndrome de manguito (OR= 4.45; IC-95%: 2.48 – 8.23) y el síndrome de túnel de carpo (OR= 4.22; IC-95%: 2.45 – 7.41) se asociaron a enfermedad laboral. Conclusiones: La prevalencia de enfermedad laboral de patología osteomuscular de miembro superior en los operarios de un cultivo de flores de la Sabana de Bogotá es del (54,4%). Se encontró una mayor asociación con el síndrome del manguito rotador y enfermedad laboral. No se encontró asociación entre la enfermedad laboral y la actividad desempeñada, el tiempo de exposición, ni con el sexo del trabajador.

Relación entre los hallazgos radiográficos y la sintomatología respiratoria en trabajadores expuestos a polvo de carbón en minería de socavón en el departamento de Boyacá, Colombia 2015

Introducción: La inhalación de polvo de carbón favorece el desarrollo de neumoconiosis, causa daños irreversibles al pulmón que se identifican radiológicamente. Los síntomas son tardíos y la patología se puede desarrollar tras varios años de exposición. Objetivo: Caracterizar los hallazgos radiográficos según la metodología de la Organización Internacional del Trabajo (OIT) 2000 y relacionarlos con la sintomatología respiratoria en trabajadores expuestos a polvo de carbón en las labores de minería de socavón en el departamento de Boyacá, Colombia, 2015. Materiales y métodos: Estudio de corte transversal realizado en 232 mineros, se indagó características sociodemográficas, signos y síntomas del sistema respiratorio. Se realizó radiografías de tórax y se aplicó la metodología OIT para describir los hallazgos. Se estableció asociación estadística a través de la prueba Chi cuadrado de Pearson. Para el procesamiento de la información se utilizó el programa SPSS statistics 2.3 Resultados: Toda la población fue de sexo masculino, con una edad promedio de 40,8 años. El cargo de picador fue el más frecuente en 72,4% de los trabajadores. Las radiografías mostraron opacidades pequeñas redondeadas (q/q) en 42%. La expectoración fue el síntoma más frecuente 66,4%. Se encontró una relación estadísticamente significativa entre el tabaquismo con las anomalía parenquimatosas (p=0,002).Conclusión: La prevalencia de neumoconiosis para el departamento de Boyacá fue de 29.7% entre los trabajadores valorados según los criterios OIT para lectura de radiografías de tórax, por lo que se requiere poner en práctica medidas de control a fin de reducir al mínimo la exposición de los trabajadores.

Técnicas de reabilitação sem abertura de vala de redes de drenagem de águas residuais

O objectivo da presente dissertação consiste na apresentação de várias técnicas de reabilitação de redes de drenagem de águas residuais sem necessidade de abertura de vala. Para esse efeito efectuou-se um levantamento das técnicas de reabilitação de colectores sem abertura de vala actualmente existente no mercado, tendo-se identificado cinco técnicas diferentes, organizadas em dois grandes grupo: Técnicas de encamisamento (i.e., encamisamento pontual - «short liner» e contínuo com manga de fibras de feltro ou com manga de fibras de vidro) e técnicas de entubamento (i.e., entubamento simples - «sliplining» e com rebentamento por destruição da tubagem existente). As técnicas de reabilitação que foram desenvolvidas foram aplicadas a dois casos de estudo diferentes: um encamisamento contínuo com mangas de fibra de vidro (cura por radiação ultravioleta) para renovar o Emissário da Cadaveira, e um entubamento com rebentamento com tubos modelares pelo processo dinâmico, primeiro caso de entubamento realizado em Portugal para renovar um troço da rede de drenagem doméstica do novo Hospital de Cascais. A apresentação de casos de estudo foi fundamental para perceber o funcionamento das técnicas de reabilitação, e deu um aspecto técnico, essencial, a esta dissertação.

Funkcjonalizacja aglikonu Spiramycyny przez zastosowanie regio- i stereoselektywnych reakcji kaskadowych

Wydział Chemii

Structure of turbulent flow over arrays of cubical roughness

The structure of turbulent flow over large roughness consisting of regular arrays of cubical obstacles is investigated numerically under constant pressure gradient conditions. Results are analysed in terms of first- and second-order statistics, by visualization of instantaneous flow fields and by conditional averaging. The accuracy of the simulations is established by detailed comparisons of first- and second-order statistics with wind-tunnel measurements. Coherent structures in the log region are investigated. Structure angles are computed from two-point correlations, and quadrant analysis is performed to determine the relative importance of Q2 and Q4 events (ejections and sweeps) as a function of height above the roughness. Flow visualization shows the existence of low-momentum regions (LMRs) as well as vortical structures throughout the log layer. Filtering techniques are used to reveal instantaneous examples of the association of the vortices with the LMRs, and linear stochastic estimation and conditional averaging are employed to deduce their statistical properties. The conditional averaging results reveal the presence of LMRs and regions of Q2 and Q4 events that appear to be associated with hairpin-like vortices, but a quantitative correspondence between the sizes of the vortices and those of the LMRs is difficult to establish; a simple estimate of the ratio of the vortex width to the LMR width gives a value that is several times larger than the corresponding ratio over smooth walls. The shape and inclination of the vortices and their spatial organization are compared to recent findings over smooth walls. Characteristic length scales are shown to scale linearly with height in the log region. Whilst there are striking qualitative similarities with smooth walls, there are also important differences in detail regarding: (i) structure angles and sizes and their dependence on distance from the rough surface; (ii) the flow structure close to the roughness; (iii) the roles of inflows into and outflows from cavities within the roughness; (iv) larger vortices on the rough wall compared to the smooth wall; (v) the effect of the different generation mechanism at the wall in setting the scales of structures.

Dispersion Experiments in Central London: The 2007 DAPPLE project

In the event of a release of toxic gas in the center of London, the emergency services would need to determine quickly the extent of the area contaminated. The transport of pollutants by turbulent flow within the complex street and building architecture of cities is not straightforward, and we might wonder whether it is at all possible to make a scientifically-reasoned decision. Here we describe recent progress from a major UK project, ‘Dispersion of Air Pollution and its Penetration into the Local Environment’ (DAPPLE, www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London (UK) during 2003, 2004, 2007, and 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because (i) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft, (ii) measurements were made under a wide variety of meteorological conditions, and (iii) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data.

Resistivity imaging survey of the Roman barrows at Bartlow, Cambridgeshire, UK

Resistivity imaging was carried out on four large Roman barrows at Bartlow in Cambridgeshire. The geophysical survey formed part of a wider research project designed to record and assess the landscape context of the largest surviving Roman burial mounds in Britain. The barrows today range in height from 6.6 m to 13.2 m and their steep profile loosed particular practical and modelling challenges. Data were obtained using a Campus Geopulse resistance meter with up to 50 electrodes spaced at 1 m intervals and lines up to 76 m long. A total of 24 lines was obtained. Topographic corrections were applied to the pseudosections, whichwere inverted using Res 2 Dinv and Res3 Dinv. Resistivity imaging was particularly successful in identifying evidence for the antiquarian explorations of the site. Central collapse features or in-filled tunnels image as high resistance features in all barrows and in one (Barrow IV) there is also a low resistance feature in the approximate position of a known antiquarian tunnel. Barrow VI had a thick covering of high-resistivity that may relate to nineteenth century landscaping and reconstruction of this monument. Resistivity imaging also revealed possible evidence for ancient revetments in all four large barrows. Copyright (c) 2006 John Wiley & Sons, Ltd.

Mean flow and turbulence statistics over groups of urban-like cubical obstacles

Direct numerical simulations of turbulent flow over regular arrays of urban-like, cubical obstacles are reported. Results are analysed in terms of a formal spatial averaging procedure to enable interpretation of the flow within the arrays as a canopy flow, and of the flow above as a rough wall boundary layer. Spatial averages of the mean velocity, turbulent stresses and pressure drag are computed. The statistics compare very well with data from wind-tunnel experiments. Within the arrays the time-averaged flow structure gives rise to significant 'dispersive stress' whereas above the Reynolds stress dominates. The mean flow structure and turbulence statistics depend significantly on the layout of the cubes. Unsteady effects are important, especially in the lower canopy layer where turbulent fluctuations dominate over the mean flow.

Dynamic modelling of a wind catcher/tower turret for natural ventilation

This paper discusses experimental and theoretical investigations and Computational Fluid Dynamics (CFD) modelling considerations to evaluate the performance of a square section wind catcher system connected to the top of a test room for the purpose of natural ventilation. The magnitude and distribution of pressure coefficients (C-p) around a wind catcher and the air flow into the test room were analysed. The modelling results indicated that air was supplied into the test room through the wind catcher's quadrants with positive external pressure coefficients and extracted out of the test room through quadrants with negative pressure coefficients. The air flow achieved through the wind catcher depends on the speed and direction of the wind. The results obtained using the explicit and AIDA implicit calculation procedures and CFX code correlate relatively well with the experimental results at lower wind speeds and with wind incidents at an angle of 0 degrees. Variation in the C-p and air flow results were observed particularly with a wind direction of 45 degrees. The explicit and implicit calculation procedures were found to be quick and easy to use in obtaining results whereas the wind tunnel tests were more expensive in terms of effort, cost and time. CFD codes are developing rapidly and are widely available especially with the decreasing prices of computer hardware. However, results obtained using CFD codes must be considered with care, particularly in the absence of empirical data.

Effect of damper and heat source on wind catcher natural ventilation performance

Experimental wind tunnel and smoke visualisation testing and CFD modelling were conducted to investigate the effect of air flow control mechanism and heat source inside rooms on wind catchers/towers performance. For this purpose, a full-scale wind catcher was connected to a test room and positioned centrally in an open boundary wind tunnel. Pressure coefficients (C-p's) around the wind catcher and air flow into the test room were established. The performance of the wind catcher depends greatly on the wind speed and direction. The incorporation of dampers and egg crate grille at ceiling level reduces and regulates the air flow rate with an average pressure loss coefficient of 0.01. The operation of the wind catcher in the presence of heat sources will potentially lower the internal temperatures in line with the external temperatures.

Utility of wind catchers for nocturnal ventilation

Wind catcher systems have been employed in buildings in the Middle East for many centuries and they are known by different names in different parts of the region. Recently there has been an increase in the application of this approach for natural ventilation and passive cooling in the UK and other countries. This paper presents the results of experimental wind tunnel and smoke visualisation testing, combined with CFD modelling, to investigate the performance of the wind catcher. For this purpose, a full-scale commercial system was connected to a test room and positioned centrally in an open boundary wind tunnel. Because much ventilation design involves the use of computational fluid dynamics, the measured performance of the system was also compared against the results of CFD analysis. Configurations included both a heated and unheated space to determine the impact of internal heat sources on airflow rate. Good comparisons between measurement and CFD analysis were obtained. Measurements showed that sufficient air change could be achieved to meet both air quality needs and passive cooling.

Interaction of nitrogen dioxide (NO2) with a monolayer of oleic acid at the air–water interface – A simple proxy for atmospheric aerosol

The reactions between atmospheric oxidants and organic amphiphiles at the air water interface of an aerosol droplet may affect the size and critical supersaturation required for cloud droplet formation. We demonstrate that no reaction occurs between gaseous nitrogen dioxide (1000 ppm in air) and a monolayer of an insoluble amphiphile, oleic acid (cis-9-octadecenoic acid), at the air water interface which removes material from the air water interface. We present evidence that the NO2 isomerises the cis-9-octadecenoic (oleic) acid to trans-9-octadecenoic (elaidic) acid. The study presented here is important for future and previous studies of (1) the reaction between the nitrate radical, NO3, and thin organic films as NO2 is usually present in high concentrations in these experimental systems and (2) the effect of NO2 air pollution on the unsaturated fatty acids and lipids found at the air liquid surface of human lung lining fluid.

Advancements in the estimation of ice particle fall speeds using laboratory and field measurements

Accurate estimates for the fall speed of natural hydrometeors are vital if their evolution in clouds is to be understood quantitatively. In this study, laboratory measurements of the terminal velocity vt for a variety of ice particle models settling in viscous fluids, along with wind-tunnel and field measurements of ice particles settling in air, have been analyzed and compared to common methods of computing vt from the literature. It is observed that while these methods work well for a number of particle types, they fail for particles with open geometries, specifically those particles for which the area ratio Ar is small (Ar is defined as the area of the particle projected normal to the flow divided by the area of a circumscribing disc). In particular, the fall speeds of stellar and dendritic crystals, needles, open bullet rosettes, and low-density aggregates are all overestimated. These particle types are important in many cloud types: aggregates in particular often dominate snow precipitation at the ground and vertically pointing Doppler radar measurements. Based on the laboratory data, a simple modification to previous computational methods is proposed, based on the area ratio. This new method collapses the available drag data onto an approximately universal curve, and the resulting errors in the computed fall speeds relative to the tank data are less than 25% in all cases. Comparison with the (much more scattered) measurements of ice particles falling in air show strong support for this new method, with the area ratio bias apparently eliminated.

On approximate electromagnetic cloaking by transformation media

We give a comprehensive study on regularized approximate electromagnetic cloaking in the spherical geometry via the transformation optics approach. The following aspects are investigated: (i) near-invisibility cloaking of passive media as well as active/radiating sources; (ii) the existence of cloak-busting inclusions without lossy medium lining; (iii) overcoming the cloaking-busts by employing a lossy layer outside the cloaked region; and (iv) the frequency dependence of the cloaking performances. We address these issues and connect the obtained asymptotic results to singular ideal cloaking. Numerical verifications and demonstrations are provided to show the sharpness of our analytical study.