DPCM coding of spectral amplitudes without positive slope overload

The author considers the problem of coding the spectral amplitudes of a sinusoidal transform coding (STC) vocoder operating at 2400 b/s, which was previously considered by R.J. McAulay and T.F. Quatieri (1987). Differential pulse code modulation (DPCM) coding of spectral amplitudes in vocoders can cause formant clipping because of positive slope overload. The author presents a modified DPCM coder that prevents positive slope overload by anticipating large spectral peaks. When the vocoder is used on speech taken from a standard telephone set, a time-varying distortion of the low-end frequencies is observed. When the modified DPCM coder is applied to the telephone-set speech, its success was obvious. The time-varying distortion of the low-end frequencies is eliminated. Performance of the STC vocoder on the telephone-set speech is essentially identical to its performance on flat-frequency-response speech     

Orthopaedic surgery in hemophilic patients with human immunodeficiency virus

Patients registered at the author's hemophilia center between 1982 and 1994 were studied to establish whether major orthopaedic surgical procedures accelerate the fall of CD4 lymphocyte counts of patients with hemophilia who are infected with the human immunodeficiency virus, and whether patients who had surgery had different rates of development of acquired immune deficiency syndrome or death when compared with patients who did not have surgery. The patients were divided into four groups: Group 1, 22 patients who were human immunodeficiency virus positive undergoing orthopaedic surgery; Group 2, 89 patients who were human immunodeficiency virus positive not undergoing orthopaedic surgery; Group 3, 18 patients who were human immunodeficiency virus negative undergoing orthopaedic surgery; and Group 4, 135 patients who were human immunodeficiency virus negative not undergoing orthopaedic surgery. There was no significant difference between the rates of decline of CD4 lymphocyte counts for patients who were human immunodeficiency virus positive who underwent surgery when compared with human immunodeficiency virus positive patients who did not undergo surgery, nor was there any significant difference between the two human immunodeficiency virus negative groups. There were no significant differences in the rate of development of acquired immune deficiency syndrome or mortality rates between patients who had surgery and those who did not.     

The rate of CD4 decline as a determinant of progression to AIDS independent of the most recent CD4 count. The Italian Seroconversion Study

Horse liver alcohol dehydrogenase contains two tryptophan residues per subunit, Trp-15 on the surface of the catalytic domain and Trp-314 buried in the interface between the subunits of the dimer. We studied the contributions of the tryptophans to fluorescence and catalytic dynamics by substituting Trp-314 with a leucine residue and making two compensatory mutations that were required to obtain a stable protein, leading to the triple mutant M303F-L308I-W314L enzyme. The substitutions increased by two- to sixfold the turnover numbers for ethanol oxidation, acetaldehyde reduction, and the dissociation constants of the coenzymes. The rate of the exponential burst phase for the transient oxidation of ethanol increased slightly, but the rate of dissociation of the enzyme-NADH complex still limited turnover of ethanol, as for wild-type enzyme. The three substitutions at the dimer interface apparently activate the enzyme by allowing more rapid conformational changes that accompany coenzyme binding, probably due to movement of the loop containing residues 293 to 298. The emission spectrum of M303F-L308I-W314L enzyme, which contains Trp-15, was redshifted compared to wild-type enzyme. Time-resolved fluorescence measurements with the triple mutant show that the decay of Trp-15 is dominated by a approximately 7-ns component. In the mutant enzyme with Trp-15 substituted with phenylalanine, the decay of Trp-314 is dominated by a approximately 4-ns component. Solute quenching data for wild-type enzyme and the mutants show that only Trp-15 is exposed to iodide and acrylamide, whereas Trp-314 is inaccessible. The luminescence properties of the tryptophan residues in the mutated enzymes are consistent with conclusions from studies of the wild-type enzyme [M. R. Eftink, 1992, Adv. Biophys. Chem. 2, 81-114].     

Outcome of orthotopic liver transplantation in patients with haemophilia

As part of environmental toxicology, it is important to assess both the carcinogenic potential of xenobiotics and their mode of action on target cells. Since dysregulation of ornithine decarboxylase (ODC), a rate-limiting enzyme of polyamine biosynthesis, is considered as an early and essential component in the process of multistage carcinogenesis, we have studied the mode of ODC induction in Syrian-hamster-embryo(SHE) cells stage-exposed to carcinogens and to non-carcinogens. One-stage (5 hr) treatment of SHE cells with 50 microM clofibrate (CLF), a non-genotoxic carcinogen, or with 0.4 microM benzo(a)pyrene (BaP), a genotoxic carcinogen, slightly decreased basal ODC activity. Using the 2-stage exposure, 1 hr to carcinogen, then replacement by TPA for 5 hr, the ODC activity was higher than that obtained with TPA alone. This ODC superinduction was not observed when SHE cells were similarly pre-treated with non-carcinogenic compounds. Several environmental chemicals, pesticides, solvents, oxidizers and drugs were investigated with this SHE cell model. With one-stage exposure, some xenobiotics decreased basal ODC activity, while for others ODC changes were not noticeable. With 2-stage exposure (chemical followed by TPA), all carcinogens amplified the TPA-inducing effect, resulting in ODC superinduction. Comparative studies of the action of carcinogens and of non-carcinogens, using 2-stage exposure protocols, clearly show a close relationship between ODC induction rate and morphological transformation frequency.     

World survey of computer-aided design

The International Institute for Applied Systems Analysis, iiasa, was established at the end of 1972 as a joint creation of countries from both East and West.iiasa is a nongovernmental, multinational autonomous scientific institution, founded for the purpose of research into problems which are either global (knowing no frontiers) or universal (applying to all nations), and into the application of systems analysis to their solution.iiasa is situated at Schloss Laxenburg, near Vienna, Austria, and scientists from all the member nations work together on various research projects, some of which tackle specific problem areas, and others of which develop methodologies in a general context.Early in 1974, the industrial-systems project identified computer-aided design as a developing technology which would be likely to influenced the development of industry considerably. In collaboration with the computer-systems project, the industrial-systems project commissioned a world-wide survey of cad. The survey covers many countries in both Eastern and Western Europe, and includes the USA and Japan.     

Taxonomy of interpolation constraints on recursive subdivision curves

Published online: 14 May 2002     

A monolithic digital chirp synthesizer chip with I andQ channels

A monolithic digital chirp synthesizer (DCS) chip has been developed using GaAs/AlGaAs HI²L technology. The 6500-HBT-gate DCS chip is capable of producing linear frequency-modulated (chirp) waveforms or single-frequency waveforms. The major components of the DCS are two 28-b pipelined accumulators, a 1.8 kb sine ROM, a 1.8 kb cosine ROM, and two 8 b digital-to-analog converters (DACs). The total chip area is 4.877 mm×6.172 mm using a minimum feature size of 1.5 μm. All components of the DCS are fully functional and the device has been clocked to 450 MHz with a power dissipation of 18 W     

The correspondence principle of linear viscoelasticity for problems that involve time-dependent regions

A version of the correspondence principle of linear viscoelasticity theory that is based on an alternative form of the Laplace transform inversion theorem and is valid for bodies that occupy time-dependent ablating regions of space is presented and used to derive solutions to certain thermoviscoelastic boundary value problems for hollow ablating right circular cylinders. The application of this version of the correspondence principle to bodies occupying fixed regions of space but for which the boundary regions, over which different types of boundary conditions are specified, vary with time is investigated and exploited to study the thermoviscoelastic problem of an infinite body containing an extending penny shaped crack on whose surface various thermal conditions may prevail.