Development and assessment of methods for detecting dementia using the human electroencephalogram

This paper makes an outline case for the need for a low-cost, easy to administer method for detecting dementia within the growing at risk population. It proposes two methods for electroencephalogram (EEG) analysis for detecting dementia that could fulfil such a need. The paper describes a fractal dimension-based method for analyzing the EEG waveforms of subjects with dementia and reports on an assessment which demonstrates that an appropriate fractal dimension measure could achieve 67% sensitivity to probable Alzheimer's disease (as suggested by clinical psychometric testing and EEG findings) with a specificity of 99.9%. An alternative method based on the probability density function of the zero-crossing intervals is shown to achieve 78% sensitivity to probable Alzheimer's disease and an estimated sensitivity to probable Vascular (or mixed) dementia of 35% (as suggested by clinical psychometric testing and EEG findings) with a specificity of 99.9%. This compares well with other studies, reported by the American Academy of Neurology, which typically provide a sensitivity of 81% and specificity of 70%. The EEG recordings used to assess these methods included artefacts and had no a priori selection of elements "suitable for analysis." This approach gives a good prediction of the usefulness of the methods, as they would be used in practice. A total of 39 patients (30 probable Alzheimer's Disease, six Vascular Dementia and three mixed dementia) and 42 healthy volunteers were involved in the study. However, although results from the preliminary evaluation of the methods are promising, there is a need for a more extensive study to validate the methods using EEGs from a larger and more varied patient cohorts with neuroimaging results, to exclude other causes and cognitive scores to correlate results with severity of cognitive status.     

Direct and real-time visualization of the disassembly of a single RecA-DNA-ATPgammaS complex using AFM imaging in fluid

RecA disassembly from circular double-stranded DNA (dsDNA) was studied by atomic force microscopy (AFM) imaging in fluid on a single molecule scale. The RecA/DNA complex was formed in the presence of ATPgammaS, and the disassembly was then initiated by buffer exchange to rinse off ATPgammaS. Performing AFM imaging in fluid allowed direct and real-time visualization of the disassembly of RecA from dsDNA in solution. It was found that RecA disassembly commenced from multiple sites both in deionized water and in buffer; the areas where RecA dissociated showed the appearance of "gaps" in the filamentous structure. RecA further disassembled either through the already existing "gaps" or by generation of new gaps. The disassembly was slower in buffer than in deionized water, suggesting that ions also contribute to the stabilization of the complex. RecA hexamers and monomers were observed in deionized water and in buffer, respectively, during the disassembly process.     

Use of Raman microscopy and band-target entropy minimization technique to differentiate physical mixture from chemical mixture in mixed metal oxides

Raman microscopy has been applied to characterize physical and chemical mixtures of mixed metal oxides. The obtained Raman mapping data were first subjected to singular value decomposition to obtain the right singular vectors, and the right singular vectors were then subjected to band-target entropy minimization (BTEM) to recover the pure component spectra of the observed species present in the sample. Subsequently, these resolved pure component spectral information was used to differentiate the physical and chemical mixtures. In addition, BTEM is also able to recover the pure component spectra of both unstable compound and its degradation product due to laser irradiation. In current study, the physical mixture of Mn₂O₃ and Co₃O₄, and the chemical mixture of CoMn₂O₄ spinel oxide were investigated.     

Parametric analysis of shape changes of alginate beads

In this article, the various elements controlling the geometry of alginate beads such as voltage, solution concentrations and extrusive rates were experimentally investigated. The findings indicated that the combination of higher voltages more concentrated CaCl₂ solutions, shorter width of electrical field and slower extrusive rates can permit the alginate beads to become smaller. Also the effect of the electrical forces that acted on the liquid droplets was found to be stronger than that of the gravity forces did. The alginate solution concentration was found to influence the beads' shape significantly. Lower concentration of 0.5% resulted in tear-like beads arrangements and a higher concentration of 5 and 8% produced pear-like and sperm-like beads configurations. In addition to obtain special alginate beads, such as elliptical and bullet like beads, outside force could be applied. The above findings could open a broad gate for future control release system developments.     

Miscible blends of poly(n-vinyl-2-pyrrolidone) with poly(3-chloropropyl methacrylate), poly(2-bromoethyl methacrylate) and poly(2-iodoethyl methacrylate)

Summary Poly(N-vinyl-2-pyrrolidone) is miscible with poly(3-chloropropyl methacrylate), poly(2-bromoethyl methacrylate) and poly(2-iodoethyl methacrylate) as shown by the optical clarity and the glass transition behaviour of the blends. The miscible blends degrade before phase separation could be induced by heating. The three T_g-composition curves can be fitted by the Gordon-Taylor equation. The implication of the Gordon-Taylor k parameters of the blends is discussed.     

Analysis of direct immobilized recombinant protein G on a gold surface

For the immobilization of IgG, various techniques such as chemical linker, thiolated protein G methods, and fragmentation of antibodies have been reported [Y.M. Bae, B.K. Oh, W. Lee, W.H. Lee, J.W. Choi, Biosensors Bioelectron. 21 (2005) 103; W. Lee, B.K. Oh, W.H. Lee, J.W. Choi, Colloids Surf. B-Biointerfaces, 40 (2005) 143; A.A. Karyakin, G.V. Presnova, M.Y. Rubtsova, A.M. Egorov, Anal. Chem. 72 (2000) 3805]. Here, we modified the immunoglobulin Fc-binding B-domain of protein G to contain two cysteine residues at its C-terminus by a genetic engineering technique. The resulting recombinant protein, RPGcys, retained IgG-binding activity in the same manner as native protein G. RPGcys was immobilized on a gold surface by strong affinity between thiol of cysteine and gold. The orientations of both IgG layers immobilized on the base recombinant protein Gs were analyzed by fluorescence microscope, atomic force microscope (AFM), and surface plasmon resonance (SPR). Our data revealed that IgG-binding activity of RPGcys on gold surface significantly increased in comparison to wild type of protein G (RPGwild), which was physically adsorbed due to absence of cysteine residue. Immobilization of highly oriented antibodies based on cysteine-modified protein G could be useful for the fabrication of immunosensor systems.     

Influence of filter media depth and vegetation on Faecal Coliform removal by stormwater biofilters

Biofilters are promising technologies that widely applied in the treatment of urban stormwater. However, the microbial removal capacity performance depends greatly on the design of biofilters. Hence, this laboratory study attempts to investigate the influence of filter media depths (i.e. 150, 250, 350 and 450 mm) and the variation of native plants, that is, Cow Grass (Axonopus compressus) and Pearl Grass (Axonopus compressus, dwarf) in removing stormwater microorganism particularly Faecal Coliform (FC). Findings showed that a minimum media depth of 300 mm was required to achieve >1 log FC removal. The mean removal of FC at 450 mm depth filter exceeded 2 log for both Cow and Pearl grass biofilter columns. Results showed that there was no statistically significant difference in vegetation type on the performance of FC removal, however, Cow grass biofilter column revealed higher FC mean log removal compared to Pearl grass biofilter column.     

Total factor productivity growth accounting in the construction industry of Singapore

Total factor productivity (TFP) determines long‐term economic growth and is a comprehensive industry‐level productivity measure. This paper proposes Jorgenson's method as an appropriate TFP measurement for the construction industry. The method is less restrictive than the conventional Chau's approach, as it does not impose the Hick Neutral Technical Change assumption. Jorgenson's method is then applied to estimate TFP growth in the construction industry of Singapore over 1984–1998. TFP growth is found down by 1.53% per annum over this period, indicating that the performance of TFP in the construction industry lags behind the rest of economy. TFP growth is also found to be fluctuating over time and tends to move in tandem with the construction business cycle.

As a monitor of progress towards TFP achievement, factors influencing TFP growth in the construction industry of Singapore over 1984–1997 are identified. Seven factors are found to be significantly related to TFP growth. Among them, economies of scale, R&D by the industry, investment allowance granted and labour unions are leading contributors to TFP growth; while foreign worker, construction accidents and pre‐cast are major hampers.

The general methodology presented in this study can be applied to other countries. Future studies are required to find appropriate indicators for factors unquantified.