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Traditional Ghanaian furniture designs are known as an exhibition of the splendor and elegance of decorative objects or decorative ornaments that carry profound philosophical and sacred meanings. The features found in Ghana’s traditional Ghanaian design can be considered as objects for international players, with their own identity and not found elsewhere. This paper therefore seeks to identify and illuminate some of these Akan cultural objects in Ghana by referring to the Ashanti region. This paper also shows with examples how these design elements can be developed and maintained by integrating them into modern furniture and interior designs or as a straightforward or adaptive design.

European regulations state a minimum boiler efficiency for the main steady-state functioning conditions and for the overall heating season conditions. In order to comply the demands of the new regulations, more and more boiler manufacturers are switching the gas boilers production to condensing functioning. In the paper we present the numerical and computational modeling of a boiler made out of packages of finned tubes and packages of smooth pipes. Validation of the computational results is made by comparison with experimental results obtained in a certified laboratory for the modelled equipment (boiler). The modelling was set on an aluminium finned tubes heat exchanger existent in the testing laboratory (part of a condensing boiler). The geometry modeling considered the discretization of the heat exchanger in several zones, characterized by homogenous flue gas flow speed, flow geometry and heat transfer characteristics (mainly feature-length). A good correlation between measured and calculated values was obtained, the error ranging +/- 1% for the total and sensible heat and for thermal efficiency.

The conical tunnel burner is an improvement of the cylindrical tunnel burner because, by maintaining all its advantages by means of burning intensification, it may also insure the flame stabilization in a wide range of regulation with considerable diminished pressure losses. Technical applications for the conical furnace burner can vary due to the limited dimensions required by the system, as well as the important thermal loads, and also because of the burning stability characteristic that spreads over an important range of regulation. The low costs required by the burner, generated mainly by its simple construction, also raise the interest for this technical solution. A physical model is proposed for the ignition and flame front stabilization. The flame front stabilization contains different steps from the ignition moment to final flame front stabilization, with specific flame front geometries and specific locations along the burner axis. The installation realised by the authors allowed the experimental study of the burning process in conical furnaces, in order to determine the temperature fields and the flame profiles. The physical model developed for this new type of application and the experimental data sets obtained (along with their interpretation) make the subject of this paper.

For technical applications, a physical model capable of predicting the particle evolution in the burning process along its trajectory through the furnace is very useful. There are two major demands: all the thermo-dynamic processes that describe the particle burning process must be accounted and the model must be written in such equation terms to allow the intervention for parameter settings and particle definition. The computations were performed for the following parameters: furnace average temperature between 700 and 1200 °C, size of the sawdust particle from 4 to 6 mm and fix carbon ignition between 500 and 900 °C. The values obtained for the characteristic parameters of the burning process ranged from 30 to 60 [kg/(h·m3)] for the gravimetrical burning speed WGh and from 150 to 280 [kW/m3] for the volumetric thermal load of the furnace QV. The main conclusion was that the calculus results are in good agreement with the experimental data from the pilot installations and the real-case measurements in the sawdust working boiler furnaces or pre-burning chambers. Another very important conclusion is that the process speed variation, when the furnace temperature changes, confirms the thermo-kinetic predictions, namely that the burning process speed decreases when the furnace temperature increases.

Viruses are organisms that need to infect a host cell in order to reproduce. The new viruses leave the infected cell and look for other susceptible cells to infect. The mathematical models for virus propagation are very similar to population and epidemic models, and involve a relatively large number of parameters. These parameters are very difficult to establish with accuracy, while variability in the cell and virus populations and measurement errors are also to be expected. To deal with this issue, we consider the parameters to be random variables with given distributions. We use a non-intrusive variant of the polynomial chaos method to obtain statistics from the differential equations of two different virus models. The equations to be solved remain the same as in the deterministic case; thus no new computer codes need to be developed. Some examples are presented.

Biofilms are colonies of bacteria that attach to surfaces by producing extracellular polymer substances. They may cause serious infections in humans and animals, and also cause problems in hydraulic machinery. In this paper we model the growth of a biofilm established on a medical implant. We assume that the biofilm's growth is given by a logistic reaction term with the growth rate being a random variable with a given distribution. This way we take into account the variability in the bacterial populations, and the measurement and experimental errors. The diffusion coefficient of the microbes is also taken to be random. A stochastic spectral representation of the parameters and the unknown stochastic process is used, together with the polynomial chaos method, to obtain a system of partial differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time. Some examples are presented.

Mathematical models are very important in epidemiology. Many of the models are given by differential equations and most consider that the parameters are deterministic variables. But in practice, these parameters have large variability that depends on the measurement method and its inherent error, on differences in the actual population sample size used, as well as other factors that are difficult to account for. In this paper the parameters that appear in SIR and SIRS epidemic model are considered random variables with specified distributions. A stochastic spectral representation of the parameters is used, together with the polynomial chaos method, to obtain a system of differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time.

Implicit methods are the natural choice for solving stiff systems of ODEs. Rosenbrock methods are a class of linear implicit methods for solving such stiff systems of ODEs. In the Rosenbrock methods the exact Jacobian must be evaluated at every step. These evaluations can make the computations costly. By contrast, W-methods use occasional calculations of the Jacobian matrix. This makes the W-methods popular among the class of linear implicit methods for numerical solution of stiff ODEs. However, the design of high-order W-methods is not easy, because as the order of the W-methods increases, the number of order conditions of the W-methods increases very fast. In this paper, we describe an approach to constructing high-order W-methods.

This paper studies round jet with large eddy simulation (LES) method, in which spectral element technique is used as spacial discritization for the large eddy simulation Navier–Stokes equations. A local spectral discretization associated with Legendre polynomials is employed on each element of the structured mesh, which allows for high accurate simulations of turbulent flows. Discontinuities across the interfaces of the elements are resolved using a Riemann solver. An isoparametric representation of the geometry is implemented, with boundaries of the domain discretized to the same order of accuracy as the solution, and explicit low-storage Runge–Kutta methods are used for time integration. LES results of round jet are presented, in which the instantaneous and statistical turbulence structures of the round jet have been captured. The probability density function, and the spectral density function of the round jet that can reflect properties of turbulence have also been estimated. The work serves the purpose of allowing fast, convenient computations and comparisons with theoretical results and the ultimate goal is to develop it into an LES code featuring spectral accuracy with minimum dissipation and dispersion, a valuable tool for round jet computations.

characteristic length and time scales of inflowing turbulent eddies are consistent with the corresponding Reynoldsaveraged Navier–Stokes profiles imposed at the inlet. The resulting large-eddy simulation method is validated against experimental data of both swirling and nonswirling turbulent jets. The application of the validated largeeddy simulation method to studies of the mechanism of swirl effects shows the following. Swirl breaks apart the typicalringstructuresofnonswirlingturbulentjetsintotwomodes:ahelicalmodeandstreamwisebraidstructures. The interaction of these two modes generates unorganized turbulence that enhances the turbulent mixing. An analysis of the mixing enhancement byswirl shows asignificantincrease of the turbulent mixing efficiency of scalars with the swirl number (of up to 21.7% for the cases considered).

In the mathematical modeling of population growth, and in particular of bacterial growth, parameters are either measured directly or determined by curve fitting. These parameters have large variability that depends on the experimental method and its inherent error, on differences in the actual population sample size used, as well as other factors that are difficult to account for. In this work the parameters that appear in the Monod kinetics growth model are considered random variables with specified distributions. A stochastic spectral representation of the parameters is used, together with the polynomial chaos method, to obtain a system of differential equations, which is integrated numerically to obtain the evolution of the mean and higher-order moments with respect to time.

We present in this paper the status of Arctic skua (Stercorarius parasiticus) among the birds that inhabit the western coast of Spitsbergen in Kapp Linne. On the species's kleptoparasitism effectively headed especially towards Kittiwake (Rissa tridactyla), a hypothesis of its double origin was issued: a) by the identity of Reynold indices regarding the wing's morphology and flying capacity in the two birds, b) the strong alikeness until superposition of the both species' emitted sounds, a fact that lets us state the hypothesis that the Stercorarius' cry during the chasing may be a key signal in the prey release by Rissa tridactyla.

Several organs (lung, skin, thyroid, heart, bone marrow) are potential targets of cobalt (Co). Whereas there is no doubt that inhalation of Co alone may cause bronchial asthma, its role in the occurrence of hard metal disease is still controversial because most cases were reported in workers exposed not only to Co but also to other substances such as tungsten carbide, titanium carbide, iron, silica and diamond. To assess whether exposure to pure Co dust (metal, oxides, or salts) may lead to adverse health effects a cross sectional study was carried out among 82 workers in a Co refinery. The results were compared with those in a sex and age matched control group. The Co group had been exposed for 8.0 years on average (range 0.3-39.4). The geometric mean time weighted average exposure assessed with personal samplers (n = 82) was about 125 micrograms/m3 and 25% of the values were higher than 500 micrograms/m3. The concentrations of Co in blood and in urine after the shift were significantly correlated with those in air. Concentration of Co in urine increased during the workweek. A slight interference with thyroid metabolism (decreased T3, T4, and increased TSH), a slight reduction of some erythropoietic variables (red blood cells, haemoglobin, packed cell volume) and increased white cell count were found in the exposed workers. The exposed workers complained more often of dyspnoea and wheezing and had significantly more skin lesions (eczema, erythema) than control workers. Within the exposed group a dose-effect relation was found between the reduction of the forced expiratory volume in one second/vital capacity and the intensity of current exposure to Co assessed by the measurement of Co in air or in urine. The prevalence of dyspnoea was related to the dustiness of the workplace as reflected by statistically significant logistic regression between this symptom and the current levels of Co in air and in urine. No difference between lung volumes, ventilatory performances, carbon monoxide diffusing capacity, and serum myocardial creatine kinase and procollagen III peptide was found between the Co and control groups and no lung abnormalities were detected on the chest radiographs in both groups. The results suggest that exposure to high airborne concentrations of Co alone is not sufficient to cause pulmonary fibrosis. This finding is compatible with experimental studies indicating that interaction of other airborne pollutants with Co particles play a part in the pathogenesis of parenchymal lung lesions.

In modeling of populations and in many other applications parameters are either measured directly or determined by fitting parameters to a mathematical model. These parameters have variability depending on experimental error, the actual population used and many other factors. In this paper we consider that those parameters are random variables with given distributions. We write and solve random differential equations that model Monod growth kinetics. This type of kinetics is useful, for example, in modeling biofilm growth.

According to a recent theoretical model, snoring is related to instability of the upper airway (UA). Factors promoting UA instability include increased gas density. The aim of this study was to test the influence of gas density on simulated snoring production and supraglottic resistance. Supraglottic pressure and flow rate (V') were measured in 10 healthy seated subjects during simulated snoring. Subjects breathed three different gas mixtures: Helium-oxygen, He 79%-O2 21% (He-O2); air; and sulphur hexafluoride-oxygen, F6S 79%-O2 21% (F6S-O2) administered in a random order. Supraglottic resistance (Rsg) was measured on its linear range during quiet breathing and V' was measured at the onset and middle of snoring. Linear Rsg increased and V' conversely decreased with gas density. These data are in agreement with predictions of a mathematical model of the upper airway showing that snoring occurs at lower flow rates when gas density is increased.

Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function

Size and distensibility of large airways have important implications for flow limitation and the efficacy of coughing. From radiological and functional data, some authors have suggested an increased size and distensibility of the trachea in cystic fibrosis (CF). Using computed tomography (CT) we compared size and distensibility of the trachea in 5 cystic fibrosis patients and five age- and height-matched healthy volunteers. Tracheal cross-sectional area was measured 25 mm below the cricoid cartilage. CT recordings were made at functional residual capacity, at 0 and +20 cmH2O mouth pressure. Inductive plethysmography was used to check that during these manoeuvres lung volume did not change and that the glottis remained open. Tracheal cross-sectional area and derived indices of tracheal distensibility were similar in the two groups. This study does not support the concept of an increased size and distensibility of the trachea in cystic fibrosis.

To determine the relationship between the expression of leukocyte-specific integrins in the airways and the airway obstruction in smokers, we analyzed hypertonic saline-induced sputum in 33 male subjects, age 64.7 +/- 0.5 yr (mean +/- SEM), with a smoking history of 12 to 94 pack-years, at the end of a 15-yr follow-up study. Average FEV(1)/VC ratio was 69 +/- 1% at the beginning of the study and 66 +/- 2% at the end of the follow-up period, and annual decline of FEV(1) was 20 +/- 3 ml/yr. Fourteen individuals exhibited airway obstruction as assessed by a FEV(1)/VC ratio lower than 63.3%. Differential leukocyte count was performed on cytospin preparations and the expression of integrin alpha (CD11a, CD11b, CD11c) and beta (CD18) chains was assessed on granulocytes and mononuclear cells by immunocytology. The numbers of neutrophils expressing CD11b and CD18, but not CD11c or CD11a, were increased in the subjects with airway obstruction compared with those without airway obstruction. CD11b- and CD18-positive neutrophils were negatively correlated with FEV(1)/VC ratio (p < 0.01). No significant correlations were found between CD11a-, CD11b-, CD11c-, CD18-positive mononuclear cells and lung function measurements. In conclusion, our results suggest that leukocyte-specific integrin CD11b/CD18 expressed on sputum polymorphonuclear leukocytes represents a marker for the smokers who develop chronic airway obstruction.

Inspiratory flow limitation (FL) during sleep has previously been reported both in obstructive sleep apnoea (OSA) patients and heavy snorers (HS). Recent results from this laboratory have shown the occurrence both of inspiratory and expiratory flow limitation during muscular relaxation in awake healthy subjects and OSA patients. In this study, we have investigated whether expiratory flow limitation occurs during sleep in heavy snorers and in patients with OSA. We studied four nonapnoeic, heavy snorers and five OSA patients. Airflow was measured with a pneumotachograph attached to a tight-fitting mask, and supraglottic pressure with a catheter placed at the supraglottic level. Scoring for flow limitation was achieved by visual inspection of 200 breaths recorded during sleep. About 20% of the respiratory cycles presented isolated inspiratory flow limitation. Approximately the same percentage was observed in heavy snorers and OSA patients. Isolated expiratory flow limitation was less frequently recorded. Coupled inspiratory and expiratory flow limitations were more numerous, especially in heavy snorers. We conclude that both in heavy snorers and obstructive sleep apnoea patients, inspiratory flow limitation is associated with expiratory flow limitation. This suggests that upper airway obstruction during sleep is both an inspiratory and expiratory event.

BACKGROUND: Smoking may cause inflammation of the airways and impairment of lung function. To determine the relationship between the type and degree of airways inflammation and the decline in lung function, leucocytes in the sputum of smokers and ex-smokers were examined. METHODS: Forty six smokers and ex-smokers of median age 64 years (25%; 75% percentiles 62;66) with a smoking history of 40.1 (31.7;53) pack years were studied with lung function tests and a questionnaire at the end of a 15 year follow up period. Sputum was induced by inhalation of hypertonic saline and differential leucocyte counts were performed on cytospin preparations. RESULTS: Adequate sputum samples were obtained in 38 subjects (78%). The ratio of forced expiratory volume in one second (FEV1) to vital capacity (VC) was 67.1 (60; 72)% and the annual decline in FEV1 was 19.4 (12;30) ml/year. Subjects with airways obstruction (FEV1/VC < 63%) had more neutrophils (77 (50;86)%) than those without airways obstruction (60 (43;73)%). The percentage of neutrophils was also significantly greater (77 (62;85)%) in those with chronic expectoration than in those without expectoration (57 (45;75)%. Increased levels of neutrophils in the sputum were correlated with a rapid decline in FEV1 over the 15 year follow up period. CONCLUSIONS: Airways obstruction and chronic expectoration, as well as accelerated decline in lung function, are associated with increased numbers of neutrophils in the sputum of smokers and ex-smokers which suggests that neutrophilic inflammation of the airways may be involved in the pathogenesis of chronic obstructive pulmonary disease.

The kidney seems more sensitive to the chronic effect of cadmium than the lung. Only minor impairments of lung function (mild form of obstructive lung disease) were found after long-term occupational exposure (less than 20 yr) to moderate concentration of cadmium oxide dust and fume. This conclusion, cannot, however be extrapolated to acute or subacute inhalational exposure. The nephrotoxicity of cadmium consists in a tubular dysfunction characterized by an increased excretion of beta 2-microglobulin and giving rise to the classical tubular proteinuria and in a glomerular dysfunction evidenced by an increased excretion of high molecular weight proteins and increased levels of beta 2-microglobulin and creatinine in plasma and giving rise to a glomerular type proteinuria. These renal changes were mainly found in workers whose cadmium concentration at time of the survey exceeded 1 microgram Cd/100 ml in blood and 10 microgram Cd/g creatinine in urine. It should, however, be stressed that higher levels of Cd in blood and in urine are not necessarily associated with the presence of excessive proteinuria. In newly exposed workers, the Cd level in blood increases progressively to a plateau after several weeks. Cadmium level in urine fluctuates more. In workers exposed for several months to an airborne concentration exceeding 200 microgram/m3, Cd concentration in urine seems mainly influenced by recent exposure. Images FIGURE 1.

Stănescu, D. C., Clément, J., and van de Woestijne, K. P. (1973).Thorax, 28, 716-720. Pulmonary resistance and maximal expiratory flowrates following isoprenaline in patients with chronic obstructive lung disease. Pulmonary resistance, maximal expiratory flowrates (measured from flow-volume curves), and lung volumes were measured in 17 patients with chronic obstructive lung disease before and 20 minutes after isoprenaline aerosols. Forced vital capacity, maximum expiratory flowrates, and pulmonary resistance all changed significantly following isoprenaline. Using a discriminant analysis, we showed that the bronchodilator effect was reflected almost completely by only two indices, pulmonary resistance and maximum expiratory flowrate at 25% of the control vital capacity. The information provided by each was independent. When the change following bronchodilatation is expressed as a percentage, pulmonary resistance carried most of the information and for practical purposes this index may be used alone.

Thirty-three subjects with bronchial asthma and 15 subjects with asthmatic bronchitis caused by occupational exposure to simple chemicals were submitted to an allergologic investigation. Essentially this consisted of skin tests, inhalation tests, determination of some types of circulating antibodies, carried out with nonirritant concentrations of simple chemicals and with usual allergens. Results indicated that bronchial asthma and asthmatic bronchitis, due to micromolecular substances, may be either irritative (28 cases) or allergic (15 cases). In five subjects the mechanism could not be established. A certain substance may give rise, in different subjects, to both types of bronchial asthma and asthmatic bronchitis mentioned above. Besides the well-known picture of bronchial asthma with reagins, the authors describe another pattern of skin and bronchial response; this pattern has many features in common with the delayed hypersensitivity.