Biomedical subjects

A Gorbach

Publications and source records attributed to A Gorbach.

3 recordsLinked to original sources

PubMed2005

Discrete breathers in Fermi-Pasta-Ulam lattices.

We study the properties of spatially localized and time-periodic excitations--discrete breathers--in Fermi-Pasta-Ulam (FPU) chains. We provide a detailed analysis of their spatial profiles and stability properties. We especially demonstrate that the Page mode is linearly stable for symmetric FPU potentials. A resonant interaction between a localized and delocalized perturbations causes weak but finite strength instabilities for asymmetric FPU potentials. This interaction induces Fano resonances for plane waves scattered by the breather. Finally we analyze the interplay between energy thresholds for breathers in the presence of strongly asymmetric FPU potentials and the corresponding profiles of the low-frequency limit of breather families.

Journal Article↗

PubMed1993

How well does a three-sphere model predict positions of dipoles in a realistically shaped head?

The electrical potential produced by a dipole in the temporal or frontal lobe was calculated for a realistically shaped scalp, skull, and brain. This potential distribution was then used with a 3-sphere model to predict the position, orientation, and strength of the dipole source. The original and predicted dipole positions differed by an average of 1.97 cm, with a difference of more than 4 cm in some cases. Control calculations demonstrated that this difference was not caused by numerical artifacts in the computation, but instead was due to a true difference between the 3-sphere and realistically shaped head models.

Brain↗

PubMed1977

A computerized prenatal record.

An entirely computerized ambulatory medical record system is operational in a large health maintenance organization. A unique subsystem was designed for use in prenatal care, in which the provider's completion of a single encounter form at the time of visit meets all the information requirements of care delivery, administration, and quality assurance. Instead of using a conventional paper chart, computer-generated summaries and flow charts are automatically provided for scheduled visits and for use as a hospital preadmission record, significantly reducing the provider effort expended on record keeping. On-line inquiry function is also available using terminals at the ambulatory center and the hospital. The computer data base has been used for quality assurance studies in prenatal care. The system is well accepted by providers, is reliable, and is cost effective.

Computers↗