Effects of Pollen Allergy on Pulmonary Function Tests

Background: To investigate the effect of high air-borne pollen count on respiratory system.Methods: This cross sectional (descriptive) study included sixty known asthmatics, of either sex and of all ages. Pollen count as per cubic meter was recorded daily during February to May as reported by meteorological department. History, clinical examination and lung function tests were recorded in each case. The Pulmonary Function Test (PFT) with pollen count of asthmatic patients was correlated.Results: The PFT of asthmatic patients were adversely affected significantly during pollen season. There was negative correlation of moderate strength with FEV1 in asthmatic patients with high air borne pollen count during the pollen season.Conclusion: Spirometry was shown to be an effective technique to study the pollen allergy problem in already asthmatic patient

Zur Modellierung des Fäulerisikos von Holzprodukten

International audienceAn empirical model for wood decay development which can be incorporated into a hygrothermal model of building physics is presented. The model is applied to the ERA-40 reanalysis data, based on six-hour weather observations in Europe, to estimate wood decay in different parts of Europe. These studies provide new tools for evaluating the durability and service life of wooden products and a preliminary European wood decay risk level map. The effects of the projected climate change on wood decay may also be considered by this methodology

"Moisture-induced stresses perpendicular to grain in timber sections exposed to European climates"

In variable humidity conditions, wood absorbs or desorbs moisture from the air. Unless the change in humidity is very slow, this will develop moisture gradients in the wood sections. These gradients will develop stresses due to constrained swelling or shrinkage strains. These stresses are named moisture-induced stresses. The present paper investigates the main parameters affecting such moisture-induced stresses, including the type of climate, the size of the timber cross-section, and the type of protective coating. A first attempt to identify moisture-induced stresses in different European climatic regions was made. For each climatic region, relative humidity and temperature histories were identified, and characteristic and mean values of yearly and daily variations were calculated. Using a finite element model implemented in Abaqus, the moisture content and stress distribution were computed on different timber cross-sections exposed to the climatic regions and protected with different types of coating. A Fickian moisture transfer model was used to compute the moisture distribution, and a mechanical model for time-dependent behaviour of wood was implemented to calculate the corresponding stress distribution. The variation of moisture was found to result in stresses of magnitudes that would probably cause cracking of wood in the perimeter of any uncoated cross-section size. The use of a protective coating, however, reduced considerably the moisture-induced stresses, and can be regarded as an effective protective measure to avoid cracking due to humidity variations. Considering European climates, Northern climates were found to result in higher surface tensile stresses than Southern climates

Modelling the hygrothermal stress in curved glulam beams

Variations of relative humidity and temperature result in moisture and temperature gradients in wood, which induce stress perpendicular to grain and may even cause cracking of the wood. To address the problem, a sequentially coupled three-dimensional (3D) finite element procedure was developed for investigation of hygrothermal stress in glulam beams, in which moisture and heat transfer were taken into consideration, and the hygrothermal deformation, creep, and mechanosorption were also included. The moisture content, temperature, and stress distributions in glulam beams were modelled successfully. The study provides insight into the mechanism of hygrothermal stress in glulam and also provides useful reference to the design of glulam structures and the design of lamina stacking sequence in production of glulam. </jats:p