An epidemiological study was undertaken to determine the prevalence of asthma in young urban and rural black (Xhosa) children. One thousand three hundred and seventy five children were studied, 694 from a Cape Town african township and 671 from a rural area in Transkei. The exercise tolerance test which required free range running at maximum effort for 6 min was used to identify asthmatic subjects. A fall of 15% or more in the post-exercise FEV1 and PEFR values was regarded as a positive result. Twenty-three children were found to be asthmatic, twenty-two from the city area, but only one from the country, giving a prevalence figure for asthma of 3.17% in the first group and 0.14% for the second. Possible reasons for these differences are discussed. The exercise tolerance test was found to be a useful tool for epidemiological studies of asthma.

Prevalence of asthma: a comparative study of urban and rural Xhosa children.

Background There is limited information on field epidemiology of bronchial asthma in Indian adults. Objectives To estimate prevalence of bronchial asthma in different regions of India and to define risk factors influencing disease prevalence. Methods A field study was conducted at Chandigarh, Delhi, Kanpur and Bangalore through a two stage stratified (urban/ rural) sampling and uniform methodology using a previously validated questionnaire. Asthma was diagnosed if the respondent answered affirmatively both to (a) whistling sound from chest, or chest tightness, or breathlessness in morning, and (b) having suffered from asthma, or having an attack of asthma in the past 12 months, or using bronchodilators. Besides demographic data, information on smoking habits, domestic cooking fuel used, atopic symptoms, and family history suggestive of asthma was also collected. Univariate and multivariate logistic regression modelling was performed to calculate odds ratio of various potential risk factors. Results Data from 73605 respondents (37682 men, 35923 women) were analysed. One or more respiratory symptoms were present in 4.3-10.5% subjects. Asthma was diagnosed in 2.28%, 1.69%, 2.05 and 3.47% respondents respectively at Chandigarh, Delhi, Kanpur and Bangalore, with overall prevalence of 2.38%. Female sex, advancing age, usual residence in urban area, lower socio-economic status, history suggestive of atopy, history of asthma in a first degree relative, and all forms of tobacco smoking were associated with significantly higher odds of having asthma. Conclusion Prevalence estimates of asthma in adults in this study, although lower than several previously reported figures, point to a high overall national burden of disease.

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Prevalence and risk factors for bronchial asthma in indian adults : A multicentre study

Two epidemiological surveys of the prevalence of bronchial asthma in schoolchildren in Taipei, Taiwan, were conducted in 1974 and 1985. The same questionnaire and school, and schoolchildren of the same age (7–15 years), were studied in these two surveys. Bronchial asthma was defined as at least three paroxysmal, recurrent attacks of wheezing and dyspnea in the previous 12 months. A total of 23,678 children were studied in 1974 and 147,373 children in 1985. Data from other Asian Pacific countries were also reviewed.The results: 1) The questionnaire was able to differentiate asthmatics from nonasthmatics on the basis of differences in methacholine challenge, intracutaneous skin testing, total eosinophil count, total serum IgE, and RAST between the two groups. 2) The prevalence of childhood asthma increased from 1.30% in 1974 to 5.07% in 1985, with boys dominating in both studies. 3) The increase in asthma prevalence could not be explained by air pollution or exposure to new allergens. 4) The prevalence of c...

Prevalence of Childhood Asthma in Taipei, Taiwan, and Other Asian Pacific Countries

Direct and large-eddy simulations of the Navier–Stokes equations are used to study the pulsating flow in a channel. The cases examined span a wide range of frequencies of the driving pressure gradient, and encompass different physical behaviors, from the quasi-Stokes flow observed at high frequencies, to a quasisteady behavior at the lowest ones. The validity of the dynamic Smagorinsky model to study this kind of unsteady flow is established by a posteriori comparison with direct simulations and experimental data. It is shown that the fluctuations generated in the near-wall region by the unsteady pressure gradient do not propagate beyond a certain distance lt from the wall, which can be estimated quite accurately by a simple eddy viscosity argument. No substantial departure from the Stokes regime at very high frequency (ω+ as high as 0.1) is observed. The time-dependent characteristics of the flow are examined in detail, as well as the topology of the coherent structures.

Numerical simulation of pulsating turbulent channel flow

Antifouling hydrolyzed polyacrylonitrile/graphene oxide membrane with spindle-knotted structure for highly effective separation of oil-water emulsion

There is wide interest in multimedia security and copyright protection due the explosion of data exchange in the Internet and the extensive use of digital media. We propose a novel video watermarking scheme based on visual cryptography and scene change detection in discrete wavelet transform domain. We start with a complete survey of the current image and video watermarking technologies, and have noticed that majority of the existing schemes are not capable of resisting all attacks. We propose the idea to use different parts of a single watermark into different scenes of a video for generation of the owner's share from the original video based on the frame mean in same scene and the binary watermark, and generation of the identification share based on the frame mean of probably attacked video. These two shares after stacking can reveal the copyright ownership. Experiments are conducted to verify the robustness through a series of experiments. The security requirement of the proposed algorithm is achieved with the visual cryptography.

Video watermarking scheme based on visual cryptography and scene change detection

Epidemiology of asthma in an urban population. A random morbidity survey.

Time-varying pipe flows driven by a harmonically pulsating inlet velocity and spanning all flow regimes have been investigated by means of numerical simulations. The Reynolds number varied from 1000 to 5000 in response to the inlet velocity oscillations. The frequency of the pulsations was varied from 1 to 10 Hz. These frequencies are markedly higher than those previously studied (maximum value of 0.025 Hz). The motivation for the use of the elevated frequency range was engendered by practical applications such as cardiovascular and respiratory systems of mammals in addition to numerous industrial applications. The simulations made use of the modified Menter transitional model. The key conclusion found here is that the use of a quasi-steady model for the prediction of fully developed friction factors is not applicable for the higher frequencies considered here. The deviations between the actual and quasi-steady friction factor values increase markedly with increasing frequency. Backflow occurs near the wa...

High-frequency pulsatile pipe flows encompassing all flow regimes

This paper proposes a hybrid model for the study of the droplet flow behavior in an immiscible medium with insoluble nonionic surfactant adhering to its interface The evolution of the surfactant concentration on the interface is modeled by the time-dependent surfactant convection-diffusion equation and solved by a finite difference scheme The fluid velocity field, the pressure and the interface curvature are calculated using the lattice Boltzmann method (LBM) for binary fluid mixtures The coupling between the LBM and the finite difference scheme is achieved through the LBM variables and the surfactant equation of state The Gunstensen LBM is used here because it provides local and independent application of a distinct interfacial tension on the individual nodes of the droplet interface The hybrid model was developed and successfully applied to droplet deformations under a variety of flow conditions

A hybrid lattice Boltzmann model for surfactant-covered droplets

In present study, the molluscicidal activity of some medicinal plant i.e. Acalypha indica, Euphorbia hirta and Ricinus communis against Lymnaea acuminata snails was studied. The toxicity of different preparations for mulluscs was time and dose dependent. According to these results it may conclude that, the ethanolic extract of Ricinus communis may be used for the pest management, however, further animal study is needed to confirm its physiological toxicity.

T.R. Singh

Papers

Video watermarking scheme based on visual cryptography and scene change detection

Epidemiology of asthma in an urban population. A random morbidity survey.

High-frequency pulsatile pipe flows encompassing all flow regimes

A hybrid lattice Boltzmann model for surfactant-covered droplets

Molluscicidal activity of some medicinal plants