Electrical degradation of polymers of styrene and substituted styrenes. 2

Summary Different substituted styrene monomers (p-amino styrene (p-AS), p-dimethylamino styrene (p-DMAS), p-trifluoromethyl styrene (p-TFMS), p-phenoxy styrene (p-PhOS), p-benzyloxy styrene (p-BeOS) and p-chloromethyl styrene (p-CIMS)) were copolymerized with styrene. Homopolymers were produced of monomers p-PhOS and p-butoxy styrene (p-BuOS). Thin films of the polymers were subjected to external partial discharges in air and the time to breakdown was measured. The stability of the polymers towards partial discharges is discussed with reference to radical formation and segmental mobility.     

Blind equalization by direct examination of the input sequences

This paper presents a novel approach to blind equalization (deconvolution), which is based on direct examination of possible input sequences. In contrast to many other approaches, it does not rely on a model of the approximative inverse of the channel dynamics. To start with, the blind equalization identifiability problem for a noise-free finite impulse response channel model is investigated. A necessary condition for the input, which is algorithm independent, for blind deconvolution is derived. This condition is expressed in an information measure of the input sequence. A sufficient condition for identifiability is also inferred, which imposes a constraint on the true channel dynamics. The analysis motivates a recursive algorithm where all permissible input sequences are examined. The exact solution is guaranteed to be found as soon as it is possible. An upper bound on the computational complexity of the algorithm is given. This algorithm is then generalized to cope with time-varying infinite impulse response channel models with additive noise. The estimated sequence is an arbitrary good approximation of the maximum a posteriori estimate. The proposed method is evaluated on a Rayleigh fading communication channel. The simulation results indicate fast convergence properties and good tracking abilities     

Prognostic impact of bone marrow karyotype in childhood acute lymphoblastic leukaemia: Swedish experiences 1986-91

The prognostic value of cytogenetic classification in acute lymphoblastic leukaemia (ALL) was evaluated in Swedish children below 16 years of age (n = 372) diagnosed between 1986 and 1991. A bone marrow karyotype was obtained in 281 cases, of which 149 (53%) showed clonal abnormalities. Event-free survival (p-EFS) was 0.64-0.69 in patients with diploid and pseudodiploid karyotype. Patients with massive hyperdiploidy (> 50 chromosomes) had the best outcome (p-EFS = 0.76) and those with hypodiploidy (< 46 chromosomes) had the worst (p-EFS = 0.33). White blood cell count and age were the strongest predictors of outcome. The karyotype reached borderline significance. The diagnostic karyotype was also a predictor of outcome after relapse, with hyperdiploid patients doing better than the others. The presence of a structural chromosomal abnormality did not constitute a negative prognostic factor when intensive chemotherapy was given.     

Analysis of the major mercapturic acid pathway metabolites of benzo[a]pyrene found in rat urine by nano-electrospray mass spectrometry

Nano-electrospray has been used in combination with high resolution and tandem mass spectrometry in the analysis of the major mercapturic acid pathway metabolites of benzo[a]pyrene (BP). Accurate mass measurements indicate that the [M-H]- ion of the major metabolite has a chemical formula C25H22NO6S, which corresponds to the deprotonated form of tetrahydro-trihydroxy-BP-S-N-acetylcysteine. Tandem mass spectrometry of this [M-H]- ion results in a collision induced dissociation spectrum identical to that of synthetic 7,8,9,10-tetrahydro-8,9,10-trihydroxy-BP-7-S-N-acetylcysteine.     

On the relation between optical basicity and phosphorus capacity of complex slags

In this work, the coexistence of monomer and dimer phosphate ions is considered and their relative proportions, as related to the slag phosphorus content, is used to accurately calculate the slag capacity of phosphorus as monomer and dimer phosphate ions respectively. The slag capacity of phosphorus as monomer phosphate ions is discussed to clarify the applicability of different scales of optical basicity. It is found that the theoretical optical basicity is an excellent measure of slag phosphorus capacity for a wide range of slags and seems not to be restricted to certain components or compositional limits. As a result, excellent relationship is displayed between phosphorus capacity, temperature and theoretical optical basicity. The influence of slag composition on equilibrium oxygen distribution is also considered and it is found that the oxygen concentration in liquid iron can be closely related to temperature and theoretical optical basicity.     

Unsymmetric hyperbolic systems and the Euler equations at low Mach numbers

Hyperbolic first order systems with a high degree of unsymmetry are ill conditioned for numerical computation. The principles for symmetrization are discussed and applied to the Euler equations at low Mach numbers. A new class of implicit one-step methods is introduced.