Techniques for analyzing frequency selective surfaces-a review

A number of representative techniques for analyzing frequency-selective surfaces (FSSs), which comprise periodic arrays of patches or apertures in a conducting screen and find important applications as filters in microwaves and optics, are discussed. The basic properties of the FSSs are reviewed and several different approaches to predicting their frequency-response characteristics are described. Some recent developments in the treatment of truncated, curved, and doubly periodic screens are mentioned and representative experimental results are included     

Electromagnetic-wave propagation along radially inhomogeneous dielectric cylinders

The results of a computational method for determining the propagation characteristics of a radially inhomogeneous dielectric cylinder are presented. A continuous variation in permittivity is represented by means of a staircase function, and the corresponding propagation problem for a cylindrically stratified dielectric is solved using a digital computer. For refractive-index profiles commonly used in optical waveguides, the propagation coefficient differs negligibly from the asymptotic value when the number of layers is equal to five.     

Solution of radiation-conduction problems with collocation method using B-splines as approximating functions

A collocation method employing B-splines as approximating functions and the Gaussian quadrature points as the collocation points is introduced for the first time to the solution of heat transfer problems governed by simultaneous conduction and radiation. It is demonstrated that this method provides an alternative noniterative technique which, with only a small number of equations, can produce solutions as accurate as the finite-difference method, and at a very reasonable computational cost By comparison with exact analytical solution for the case of pure radiation, it is shown that, for up to moderate values of optical thickness, one needs to solve no more than 6 equations to obtain an accuracy better than 2%. The method with these characteristics appears to be an attractive candidate for the solution of radiation-conduction problems pertaining to LMFBR core disruptive meltdown accident analyses.     

Women's attitudes to mastectomy for breast cancer

One hundred patients who had been subjected to mastectomy for carcinoma were interviewed retrospectively to gauge their attitudes to any physical and/or emotional disabilities relating to their operation or disease. It was found that 40% of the patients had delayed for longer than a month after the onset of symptoms before seeking medical advice, but the reasons for this were not readily forthcoming. However, fear of mastectomy was not a common cause. Anxiety and embarassment due to an absent breast occurred in about one-third of patients, and did not diminish with time. Knowledge and the use of mammary prostheses was far from universal, and disturbingly only two-thirds were counselled in these matters by their medical advisers. Physical complications were common, particularly lymphoedema of the arm, and as expected this was closely related to the type and extent of treatment undertaken.     

Raman spectroscopic analysis of biochemical changes in individual triglyceride-rich lipoproteins in the pre- and postprandial state

Individual triglyceride-rich lipoprotein (TGRL) particles derived from human volunteers are nondestructively analyzed by laser tweezers Raman microspectroscopy, and information on their composition and distribution is obtained. The Raman signature of single optically trapped very low-density lipoproteins (VLDL), a subclass of TGRL, which play an important role in cardiovascular disease, exhibits distinct peaks associated with molecular vibrations of fatty acids, proteins, lipids, and structural rearrangements of lipids. Our analysis of pre- and postprandial VLDL exhibits the signature of biochemical changes in individual lipoprotein particles following the consumption of meals. Interaction of VLDL with endothelium leads to the breakdown of complex triacylglycerols and the formation of a highly ordered core of free saturated fatty acids in the particle. A particle distribution analysis reveals trends in the degree to which this process has occurred in particles at different times during the postprandial period. Differences in particle distributions based on the different ratios of polyunsaturated to saturated fats in the consumed meals are also easily discerned. Individual lipoprotein particles hydrolyzed in vitro through addition of lipoprotein lipase (LpL) exhibit strikingly similar changes in their Raman spectra. These results demonstrate the feasibility of monitoring the dynamics of lipid metabolism of individual TGRL particles as they interact with LpL in the endothelial cell wall using Raman spectroscopy.     

Development of a simple algorithm for the detection of chilling injury in cucumbers from visible/near-infrared hyperspectral imaging

Hyperspectral images of cucumbers under a variety of conditions were acquired to explore the potential for the detection of chilling-induced damage in whole cucumbers. Region of interest (ROI) spectral features of chilling injured areas, resulting from chilling treatment at 0 degrees C, showed the reduction of reflectance intensity over the period at post-chilling room temperature (RT) storage. A large spectral difference between good, smooth skins and chilling-injured skins occurred in the 700-850 nm visible/near-infrared (NIR) region. Both simple band ratio algorithms and principal component analysis (PCA) were attempted to discriminate the ROI spectra of good cucumber skins from those of chilling injured ones. Results revealed that both the dual-band ratio algorithm (R(811nm)/R(756nm)) and a PCA model from a narrow spectral region of 733-848 nm can detect chilling-injured skins with a success rate of over 90%. The results also suggested that chilling injury is relatively difficult to detect at the initial post-chilling RT stage, especially during the first 0-2 days in storage, due to insignificant manifestation of chilling induced symptoms.     

A novel dengue fever (DF) and dengue haemorrhagic fever (DHF) analysis using artificial neural network (ANN)

Dengue fever (DF) is an acute febrile viral disease frequently presented with headache, bone or joint and muscular pains, and rash. A significant percentage of DF patients develop a more severe form of disease, known as dengue haemorrhagic fever (DHF). DHF is the complication of DF. The main pathophysiology of DHF is the development of plasma leakage from the capillary, resulting in haemoconcentration, ascites, and pleural effusion that may lead to shock following defervescence of fever. Therefore, accurate prediction of the day of defervescence of fever is critical for clinician to decide on patient management strategy. To date, no known literature describes of any attempt to predict the day of defervescence of fever in DF patients. This paper describes a non-invasive prediction system for predicting the day of defervescence of fever in dengue patients using artificial neural network. The developed system bases its prediction solely on the clinical symptoms and signs and uses the multilayer feed-forward neural networks (MFNN). The results show that the proposed system is able to predict the day of defervescence in dengue patients with 90% prediction accuracy.     

Synthesis and characterization of surface-functionalized conducting polyaniline-chitosan nanocomposite

We describe in this paper an easy route to the synthesis of a novel surface-functionalized conducting polyaniline-chitosan nanocomposite. A stable colloidal dispersion was prepared when aniline was polymerized in the presence of chitosan as the steric stabilizer. TEM study shows that these surface-functionalized polyaniline-chitosan nanoparticles have rice-grain morphologies. The effect of reaction parameters on the mean size of the polyaniline-chitosan nanoparticles was studied. The steric electrostatic interaction between segments of these two polymers explains the excellent storage stability of the polyaniline-chitosan dispersion. Reaction parameters were optimized in order to get stable polyaniline-chitosan dispersion. The chemical structures of polyaniline-chitosan nanocomposite were characterized. FT-IR spectra of the polyaniline-chitosan nanocomposite show that there exist a certain interaction between polyaniline and chitosan. X-ray photoelectron spectroscopy spectra show that chitosan is largely present at the surface of polyaniline-chitosan nanoparticles. The electrical conductivity of the polyaniline-chitosan nanocomposite increases with increasing the amount of polyaniline to a high value of 0.25 S/cm.     

Convenient access both to highly antimalaria-active 10-arylaminoartemisinins, and to 10-alkyl ethers including artemether, arteether, and artelinate

An economical phase-transfer method is used to prepare 10-arylaminoartemisinins from DHA and arylamines, and artemether, arteether, and artelinate from the corresponding alcohols. In vivo sc screens against Plasmodium berghei and P. yoelii in mice reveal that the p-fluorophenylamino derivative 5 g is some 13 and 70 times, respectively, more active than artesunate; this reflects the very high sc activity of 10-alkylaminoartemisinins. However, through the po route, the compounds are less active than the alkylaminoartemisinins, but still approximately equipotent with artesunate.     

Hygroscopicity of water-soluble organic compounds in atmospheric aerosols: amino acids and biomass burning derived organic species

Amino acids and organic species derived from biomass burning can potentially affect the hygroscopicity and cloud condensation activities of aerosols. The hygroscopicity of seven amino acids (glycine, alanine, serine, glutamine, threonine, arginine, and asparagine) and three organic species most commonly detected in biomass burning aerosols (levoglucosan, mannosan, and galactosan) were measured using an electrodynamic balance. Crystallization was observed in the glycine, alanine, serine, glutamine, and threonine particles upon evaporation of water, while no phase transition was observed in the arginine and asparagine particles even at 5% relative humidity (RH). Water activity data from these aqueous amino acid particles, except arginine and asparagine, was used to revise the interaction parameters in UNIQUAC functional group activity coefficients to give predictions to within 15% of the measurements. Levoglucosan, mannosan, and galactosan particles did not crystallize nor did they deliquesce. They existed as highly concentrated liquid droplets at low RH, suggesting that biomass burning aerosols retain water at low RH. In addition, these particles follow a very similar pattern in hygroscopic growth. A generalized growth law (Gf = (1 - RH/100)-0.095) is proposed for levoglucosan, mannosan, and galactosan particles.