Importance-driven focus of attention

This paper introduces a concept for automatic focusing on features within a volumetric data set. The user selects a focus, i.e., object of interest, from a set of pre-defined features. Our system automatically determines the most expressive view on this feature. A characteristic viewpoint is estimated by a novel information-theoretic framework which is based on the mutual information measure. Viewpoints change smoothly by switching the focus from one feature to another one. This mechanism is controlled by changes in the importance distribution among features in the volume. The highest importance is assigned to the feature in focus. Apart from viewpoint selection, the focusing mechanism also steers visual emphasis by assigning a visually more prominent representation. To allow a clear view on features that are normally occluded by other parts of the volume, the focusing for example incorporates cut-away views.     

High-resolution cell outline segmentation and tracking from phase-contrast microscopy images

Accurate extraction of cell outlines from microscopy images is essential for analysing the dynamics of migrating cells. Phase-contrast microscopy is one of the most common and convenient imaging modalities for observing cell motility because it does not require exogenous labelling and uses only moderate light levels with generally negligible phototoxicity effects. Automatic extraction and tracking of high-resolution cell outlines from phase-contrast images, however, is difficult due to complex and non-uniform edge intensity. We present a novel image-processing method based on refined level-set segmentation for accurate extraction of cell outlines from high-resolution phase-contrast images. The algorithm is validated on synthetic images of defined noise levels and applied to real image sequences of polarizing and persistently migrating keratocyte cells. We demonstrate that the algorithm is able to reliably reveal fine features in the cell edge dynamics.     

Behavioral markers and recognizability of the smile of enjoyment

Several age-dependent modifications of inner mitochondrial membrane and synaptosomal plasma membrane proteins from different brain regions of 4-, 12-, 18- and 24-month-old male Wistar rats, were observed. Some proteins, identified by immunoblotting assay as various subunits of mitochondrial respiratory chain complexes and calmodulin, were particularly impaired. Chronic treatment with CDP-choline at a dose of 20 mg/kg body weight per day for 28 days caused significant changes in the amounts of several of the above mentioned proteins. Most of the proteins, which decreased during aging, showed a significant increase after CDP-choline treatment compared with the corresponding control values at the same age. The effect of CDP-choline might be due to: the increased availability of cytidylic nucleotides, which in the brain are present in limited amounts compared to the other nucleotides; the increased content of total adenine nucleotides; the improvement of brain energy metabolism.     

Ultrasonic Doppler measurement using a pseudo-continuous mode

A pseudo-continuous ultrasound Doppler method was studied theoretically and experimentally. The principle of the method is based on the pulsed-wave mode. Short bursts are emitted with a high pulse repetition frequency, and demodulated echoes are integrated between emitted pulses. Gaps arise in the measurable range due to the lost echoes during emitting time, but a method for partly solving this problem that uses two alternating pulse repetition frequencies was suggested. The proposed pseudo-continuous method is useful for measuring high blood velocities, up to 3.8 m/s, with an emitted frequency of 3.2 MHz, at any depth up to 17 cm. Using the pulsed-wave mode, the maximum measurable velocity under similar conditions would be only 0.6 m/s. Thus, the maximum measurable velocity is six times higher in the pseudo-continuous mode. These results demonstrate the possibility of measuring high blood-flow velocities using a transducer and electronics compatible with the pulsed-wave mode     

How should we organize to do informatics? Report of the ACMI Debate at the 1997 AMIA Fall Symposium

The dielectric properties of the human skin stratum corneum (SC) in the frequency range higher than 107 Hz are not well understood because of the difficulty in selective scanning of the SC area in vivo. The present study was carried out to make clear factors responsible for the dielectric properties using a measuring system specially developed for the study of SC [S. Naito, M. Hoshi, S. Mashimo, Anal. Biochem. 251 (1997) 163-172]. We found that the dielectric properties of SC can be expressed by the linear combination of two relaxation processes and d.c. conduction. The faster relaxation is that of free water. The slower relaxation and d. c. conduction were analyzed using a model assuming interfacial polarization between dissimilar materials. We concluded that the polarization is the origin of the slower relaxation process because the experimental data could be well interpreted according to the above mechanism. We also concluded that the polarization of swelled SC locates at the interface between SC cells and the intercellular lipid layer, or at the interface between the lipophilic and the hydrophilic part of the lamellar structured intercellular lipid layer.     

Queueing analysis of general loop systems

This paper is concerned with general loop systems in which each of several buffered units may exchange data with any other unit via a single oneway loop channel. The traffic is described in terms of stationary stochastic processes with independent increments. The queues of data waiting for transmission which develop at the different units are investigated. The queueing discipline assumed here accords data with longer transmission paths preemptive priority over those with shorter paths. For such systems expected queue lengths and waiting times in the steady state are calculated for all units and priority classes. An equivalence is established between general loop systems and systems of a much simpler structure and is used in the derivation.     

A Critical Review of Human Performance Reliability Predictive Methods

Similarities and differences among 22 methods of quantitatively predicting operator and technician performance are described. Emphasis has been given to eight methods most fully developed and most likely to be used by system engineers. Two general techniques are employed: analysis of historical data and computer-simulation of behavioral processes. No general purpose methodology is available; each method deals with some types of tasks and systems more efficiently than others. In general, simulation-based methods are more powerful than nonsimulation methods. Most methods output probability estimates of successful task/system performance and completion time, but are relatively insensitive to equipment design parameters, manpower selection and training needs. With only one exception no operability method utilizes a formal data base as input and in most cases the parameters these input data describe are not specifically indicated. For most methods validation and/or system application data are either lacking or incomplete.