Improving the biodegradability of grain distillery wastewater for use as UASB substrate by combinations of ozonation/enzymatic pre-treatments.

The effect of ozonation and enzyme combination pre-treatments on the composition of grain distillery wastewater (GDWW) was investigated. Exposure of UASB granules to these pre-treated GDWW was evaluated by determining the effect on granule activity, visual appearance and lipid content of the granules. Pre-treatments involving a pre-ozonation step were found to be more effective in reducing the lipid and COD content of GDWW. The higher the lipid and COD reduction achieved by the pre-treatments the higher the granule activity after 24 d exposure, the lower the lipid content in the granule and the less severe the formation of an encapsulating layer.     

The wrap-around problem and optimal padding in the exit wave reconstruction using HRTEM images

A free fast Fourier transform software FFTW (www.fftw.org) is used in the exit wave reconstruction and shown to be able to handle images of any size effectively. The wrap-around problem commonly encountered in the exit wave reconstruction is investigated, and a new padding scheme is proposed and its performance is investigated. It is shown that while the usual wrap-around problem may be solved via padding the input high-resolution transmission electron microscopy (HRTEM) images with zero or averaged image intensities, the reconstructed exit wave at its boundary is inevitably distorted by the discontinuity of image intensities at the boundary. The proposed new padding scheme is shown to be able to provide a good estimate of the image intensities immediately outside the boundaries of the HRTEM images, reducing the estimated image intensity discontinuity across the boundaries and therefore providing a larger undistorted view of the exit wave.     

Sub-MeV tunably polarized X-ray production with laser Thomson backscattering

Reported in this article is the generation of unique polarized x-rays in the sub-MeV region by means of the Thomson backscattering of the Nd:YAG laser photon with a wavelength of 1064 nm on the 150 MeV electron from the microtron accelerator. The maximum energy of the x-ray photons is estimated to be about 400 keV. The total energy of the backscattered x-ray pulse is measured with an imaging plate and a LYSO scintillator. The angular divergence of the x-rays is also measured by using the imaging plate. We confirm that the x-ray beam is polarized according to the laser polarization direction with the Compton scattering method. In addition, we demonstrate the imaging of the object shielded by lead with the generated x-rays.     

Modeling Stochastic Dynamical Systems for Interactive Simulation

We present techniques for constructing approximate stochastic models of complicated dynamical systems for applications in interactive computer graphics. The models are designed to produce realistic interaction at low cost.
We describe two kinds of stochastic models: continuous state (ARX) models and discrete state (Markov chains) models. System identi cation techniques are used for learning the input-output dynamics automatically, from either measurements of a real system or from an accurate simulation. The synthesis of behavior in this manner is several orders of magnitude faster than physical simulation.We demonstrate the techniques with two examples: (1) the dynamics of candle ame in the wind, modeled using data from a real candle and (2) the motion of a falling leaf, modeled using data from a complex simulation. We have implemented an interactive Java program which demonstrates real-time interaction with a realistically behaving simulation of a cartoon candle ame. The user makes the ame animation icker by blowing into a microphone.     

Secondhand smoke and respiratory ill health in current smokers

Background: Numerous studies have concluded that secondhand smoke (SHS) is harmful to non-smokers but controversy persists regarding its effects on smokers. The impact of SHS exposure on the acute respiratory health of current active smokers was examined using a cross sectional design. Methods: 9923 uniformed staff in the Hong Kong Police Force completed a standardised questionnaire on current and past smoking, SHS exposure at home and at work, acute respiratory symptoms, and recent physician consultation. 3999 male current smokers were included in the analysis. Results: About 5% of the smokers were exposed to SHS at home only, 53% were exposed at work only, and 30% were exposed both at home and at work. The prevalence ratios for respiratory symptoms (throat and nasal problems, cough, phlegm, and wheeze), physician consultation, and self medication were higher for those who were exposed to SHS at home or at work. The odds ratios of reporting one or more respiratory symptoms, for SHS exposures at home or at work, were 1.33 (95% confidence interval (CI) 1.12 to 1.59) and 1.66 (95% CI 1.36 to 2.02) respectively, after adjusting for age, marital status, education, rank and duties, exposure to self perceived dusty or polluted environment in previous job, and total dose of active smoking. The adjusted odds ratios showed significant positive dose–response gradients with SHS exposure at home, at work, and at both places combined. Conclusions: SHS exposure is strongly associated with increased acute respiratory symptoms and recent outpatient service utilisation in current smokers. If the association is causal, public health action to limit SHS exposure could also benefit smokers.     

Evaluation of software for multiple imputation of semi-continuous data

It is now widely accepted that multiple imputation (MI) methods properly handle the uncertainty of missing data over single imputation methods. Several standard statistical software packages, such as SAS, R and STATA, have standard procedures or user-written programs to perform MI. The performance of these packages is generally acceptable for most types of data. However, it is unclear whether these applications are appropriate for imputing data with a large proportion of zero values resulting in a semi-continuous distribution. In addition, it is not clear whether the use of these applications is suitable when the distribution of the data needs to be preserved for subsequent analysis. This article reports the findings of a simulation study carried out to evaluate the performance of the MI procedures for handling semi-continuous data within these statistical packages. Complete resource use data on 1060 participants from a large randomized clinical trial were used as the simulation population from which 500 bootstrap samples were obtained and missing data imposed. The findings of this study showed differences in the performance of the MI programs when imputing semi-continuous data. Caution should be exercised when deciding which program should perform MI on this type of data.