A general computational method for converting normal spectra into derivative spectra

The mathematical problem of converting a normal spectrum into the corresponding first- and second-derivative spectra is formulated as an integral equation of the first kind. Tikhonov regularization is then applied to solve the spectral conversion problem. The end result is a set of linear algebraic equations that takes in as input the original spectrum and produces as output the second-derivative spectrum, which is then integrated to yield the first-derivative spectrum. Noise amplification is kept under control by adjusting the regularization parameter (guided by generalized cross-validation) in the algebraic equations. The performance of this procedure is demonstrated by applying it to different types of spectral data taken from the literature.     

The retention of large particles (greater than 2mum) in fibrous filters

A simple method of testing fibrous filters to obtain the grade efficiency curve in the particle size range 2-22 mum is described. Dust collected by the method has been used to measure the retention efficency of model filters and it is shown that there is a maximun in the grade efficency curve. The influence of relative humidity on filter behaviour has been investigated. It is shown that the efficiency of filtration in high particle inertia systems increases with increasing relative humidity. It is considered that the reason for this is an increase in particle-fiber adhesion force.     

A constrained neural network Kalman filter for price estimation in high frequency financial data

In this paper we present a neural network extended Kalman filter for modeling noisy financial time series. The neural network is employed to estimate the nonlinear dynamics of the extended Kalman filter. Conditions for the neural network weight matrix are provided to guarantee the stability of the filter. The extended Kalman filter presented is designed to filter three types of noise commonly observed in financial data: process noise, measurement noise, and arrival noise. The erratic arrival of data (arrival noise) results in the neural network predictions being iterated into the future. Constraining the neural network to have a fixed point at the origin produces better iterated predictions and more stable results. The performance of constrained and unconstrained neural networks within the extended Kalman filter is demonstrated on "Quote" tick data from the $/DM exchange rate (1993-1995).     

Subtypes of stalking (obsessional following) in adolescents

Stalking, which has been given the clinical term "obsessional following", is repetitive threatening or harassing behavior that creates a fear of harm in the victim. Empirical and theoretical literature on this form of behavior is beginning to develop and focuses primarily on adults. Three major subtypes of obsessional following have been identified: erotomania, love obsessional, and simple obsessional/borderline erotomania. Using this typology and available empirical research, a context is set in which three cases of adolescent obsessional following are discussed and analysed. These cases document that stalking/obsessional following occurs in adolescents and that important similarities and differences appear to exist between adult and adolescent offenders. Hypotheses are generated to encourage further study of this significant problem.     

Chemotherapy accelerates the development of acquired immune responses to Schistosoma haematobium infection

Treatment of 41 Schistosoma haematobium-infected children, 5-16 years old, with the drug praziquantel induced a switch from a predominantly IgA-specific antibody response to a predominantly IgG1 response within 12 weeks. A cross-sectional survey suggests that the same switch occurs naturally, but over several years, as children age (n = 251). The switch may be driven by alterations in cytokine levels in response to the release of antigens by dead or damaged parasites. Adults are more resistant to schistosome infection than children, and the switch to an "adult" response suggests that praziquantel treatment may have an immunizing effect, with benefits extending beyond a transient reduction in levels of infection.