Computer system buses

A common bus, carrying information and electrical power between the various components of a digital system, is as important a part of the system as the microprocessor chip itself. The electrical properties of buses often cause design problems as insufficient attention is paid to them. This article deals with the properties of three types of bus line, considering the interfacing circuitry required by each type in detail.     

Transformational solution of singular linear-quadratic control problems

General linear-quadratic singular variational problems with free end-point are studied. An algorithm is presented, involving the execution of a sequence of coordinate basis transformations in the state and control space; the algorithm establishes whether a prescribed problem has a solution, determining the optimal control and performance index in case the solution exists.     

Multicomponent Crystal Systems of Known Antimalarial Drug Molecules

Potential drug molecules are often discarded due to poor physicochemical properties and pharmacokinetic profiles. As such, research into the use of multicomponent crystal systems (such as salts and co‐crystals) is currently being conducted with the aim of improving the properties of the molecule, without altering the bioactivity of the drug. Although numerous studies have been performed on a wide variety of drug molecules, research with antimalarial drug molecules seems to have been neglected. With many of the current drugs becoming inactive due to resistance, there is an urgent need to find effective drugs with good pharmacokinetic profiles. The objective of this review is therefore to determine the extent to which multicomponent crystal systems have been used in antimalarial chemotherapy and whether this method provides a viable alternative to discarding potential drug candidates.     

A Method for the Removal of Sulfur Dioxide from Exhaust Gas Utilizing Pulsed Streamer Corona for Electron Energization

The performance of a new method using pulsed streamer corona for the removal of SO2 from humid air has been evaluated. The pulsed streamer corona produces energetic free electrons that excite, dissociate, and ionize gas molecules, forming radicals that enhance the gas-phase chemical reactions that convert SO2 to acid mist and/or particulate aerosols. The aerosols are then collected by conventional means, i.e., by electrostatic precipitator or bag filter. The SO2 removal efficiency was compared with that of the electron-beam and dc corona flue-gas treatment processes. The comparison demonstrates the advantage of the novel method.     

Assessing the effects of selection bias on validity data for the General Aptitude Test Battery.

Previous analyses have suggested that the database of 755 studies of the validity of the General Aptitude Test Battery (GATB) demonstrates a small but consistent positive correlation with criteria relevant to job performance. Critics have noted that some of the validity studies conducted were not included in the database and have speculated that these studies may have found negligible or even negative validities, so that the extant database is subject to selection bias. The authors use a mathematical model to estimate the magnitude of possible selection and its effects on the mean and variance of GATB validities. Although evidence of selection is found for some GATB scales and composites, the estimated effect of selection is probably too small to influence conclusions about the validity of the GATB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Periodic array of staggered planar cracks in an anisotropic elastic medium

The problem of determining the elastic displacements and stresses in an infinite anisotropic medium containing a periodic array of staggered planar cracks is considered. It is reduced to a system of Hadamard finite-part singular (hypersingular) integral equations with the crack-opening displacements as unknown functions. The integral equations may be solved numerically by a collocation technique. Numerical results for specific cases involving isotropic and transversely isotropic materials are obtained.     

Dynamics of helium films

We present quantitative calculations for the static structure and the dynamics of quantum liquid films on a translationally invariant substrate. The excitation spectrum is calculated by solving the equations of motion for time-dependent one- and two-body densities. We find significant corrections to the Feynman spectrum for the phonon-like collective excitations.     

Alternative routes of measles immunization: a review

Comparative observations of the effects of cholinergic and adrenergic agonists (such as pilocarpine, phenylephrine and isoproterenol) on the secretion of salivary fluid and of secretory granules from the lingual epithelium and the lingual gland in the Tokyo Daruma pond frog, Rana porosa porosa, were made by light and transmission electron microscopy. The effect of pilocarpine on the loss of cytoplasm in both the lingual epithelium and the lingual gland was the strongest, and that of isoproterenol was the weakest. Transmission electron microscopy revealed that electron-dense granules, located in cells in both the lingual epithelium and the lingual gland, were discharged by exocytosis after stimulation by phenylephrine and isoproterenol. Immediately before secretion of these granules, they became somewhat larger and round or distorted in shape. However, after administration of pilocarpine, no obvious discharge of electron-dense granules was apparent and, instead, granules in some cells began deteriorating within the cells and those in other cells developed electron-dense and electron-lucent areas. A dot-like pattern was recognized in the electron-dense areas of these granules. These phenomena were assumed to be secondary effects accompanying the secretion of salivary fluid from cells of the lingual epithelium and the lingual gland. By contrast, mucous granules in the lingual gland were secreted by a holocrine process.     

Early adolescent peer orientation and adjustment during high school.

The long-term consequences of early adolescents' orientation toward peers for their adjustment during high school were assessed. Approximately 1,200 adolescents completed questionnaires in the 7th grade and in the 10th or 12th grades; course grades were also obtained from the students' school records. Early adolescents who were willing to sacrifice their talents, school performance, and parents' rules engaged in greater problem behavior and evidenced lower academic achievement than did other adolescents during high school. The poorer adjustment of adolescents with this extreme orientation toward peers was mediated by their reported involvement in deviant peer groups. In contrast, a tendency to seek advice from peers more than from parents during early adolescence had little implication for later adjustment. Discussion focuses on the need to consider the role of peer dependence along with the effects of supportive friendships during adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)