Phase locked loop-based clock synthesizer for reconfigurable analog-to-digital converters

Analog Integrated Circuits and Signal Processing - This paper presents the complete design of a phase locked loop-based clock synthesizer for reconfigurable analog-to-digital converters. The...     

Formalization of Ring Theory in PVS

This paper presents a PVS development of relevant results of the theory of rings. The PVS theory includes complete proofs of the three classical isomorphism theorems for rings, and characterizations of principal, prime and maximal ideals. Algebraic concepts and properties are specified and formalized as generally as possible allowing in this manner their application to other algebraic structures. The development provides the required elements to formalize important algebraic theorems. In particular, the paper presents the formalization of the general algebraic-theoretical version of the Chinese remainder theorem (CRT) for the theory of rings, as given in abstract algebra textbooks, proved as a consequence of the first isomorphism theorem. Also, the PVS theory includes a formalization of the number-theoretical version of CRT for the structure of integers, which is the version of CRT found in formalizations. CRT for integers is obtained as a consequence of the general version of CRT for the theory of rings.

     

Temperament and substance abuse in schizophrenia: is there a relationship?

Dyspnea may be easily appreciated during exercise with dyspneic scales, but methodological standardisation still needs to be specified. Authors review the basic physiological mechanism relating dyspnea to indices obtained during a stress test. They propose to use the dyspnea/VE relationship. With the concept of dyspneic threshold (close to the ventilatory threshold) and the ramp that both could be modified (for instance by rehabilitation programmes including exercise training). Interpretation of dyspnea during an exercise test obviously needs to be integrated with other parameters studied during exercise.     

Massive transformation and absolute stability

Under carefully chosen conditions, solidification theory may be applied to solid-state transformations, and this has been done here for composition-invariant diffusion transformations. The predictions of the modeling are compared with isovelocity experiments in two iron systems, Fe-7.29 wt pct Cr and Fe-3.1 wt pct Ni. The ferrite to austenite phase transformation is used to demonstrate that stabilization of a planar transformation front at absolute stability is the natural lower velocity limit for a composition-invariant (massive) transformation. The results of the model, which includes nonequilibrium effects, clearly show that steady-state plane-front growth leading to composition invariance can be obtained at various temperatures depending on the growth velocity. In the lower velocity range, at the limit of absolute stability (of the order of 10 μm/s in the systems studied), the transformation interface moves under conditions of local equilibrium, and the temperature corresponds to the lower solvus temperature. At higher velocity (of the order of the interface diffusion rate, which in these systems is of the order of cm/s), the transformation is predicted to proceed at temperatures close to T ₀. At even higher rates, atom attachment kinetic undercooling will decrease the transformation temperature with respect to T ₀. In some cases, this temperature might even drop below the lower solvus. This article is based on a presentation made at the symposium entitled “The Mechanisms of the Massive Transformation,” a part of the Fall 2000 TMS Meeting held October 16–19, 2000, in St. Louis, Missouri, under the auspices of the ASM Phase Transformations Committee.     

A new method for seed oil body purification and examination of oil body integrity following germination

Plant seeds store triacylglycerols as energy sources for germination and postgerminative growth of seedlings. The triacylglycerols are preserved in small, discrete, intracellular organelles called oil bodies. A new method was developed to purify seed oil bodies. The method included extraction, flotation by centrifugation, detergent washing, ionic elution, treatment with a chaotropic agent, and integrity testing by use of hexane. These processes subsequently removed non-specifically associated or trapped proteins within the oil bodies. Oil bodies purified by this method maintained their integrity and displayed electrostatic repulsion and steric hindrance on their surface. Compared with the previous procedure, this method allowed higher purification of oil bodies, as demonstrated by SDS-PAGE using five species of oilseeds. Oil bodies purified from sesame were further analyzed by two-dimensional gel electrophoresis and revealed two potential oleosin isoforms. The integrity of oil bodies in germinating sesame seedlings was examined by hexane extraction. Our results indicated that consumption of triacylglycerols reduced gradually the total amount of oil bodies in seedlings, whereas no alteration was observed in the integrity of remaining oil bodies. This observation implies that oil bodies in germinating seeds are not degraded simultaneously. It is suggested that glyoxisomes, with the assistance of mitochondria, fuse and digest oil bodies one at a time, while the remaining oil bodies are preserved intact during the whole period of germination.