1,723 research outputs found
A Bayesian test for the appropriateness of a model in the biomagnetic inverse problem
This paper extends the work of Clarke [1] on the Bayesian foundations of the
biomagnetic inverse problem. It derives expressions for the expectation and
variance of the a posteriori source current probability distribution given a
prior source current probability distribution, a source space weight function
and a data set. The calculation of the variance enables the construction of a
Bayesian test for the appropriateness of any source model that is chosen as the
a priori infomation. The test is illustrated using both simulated
(multi-dipole) data and the results of a study of early latency processing of
images of human faces.
[1] C.J.S. Clarke. Error estimates in the biomagnetic inverse problem.
Inverse Problems, 10:77--86, 1994.Comment: 13 pages, 16 figures. Submitted to Inverse Problem
InGaAsP/InP undercut mesa laser with planar polyimide passivation
An undercut mesa laser is fabricated on an n + -InP substrate using a single step liquid phase epitaxy growth process and a planar structure is obtained by using a polyimide filling layer. The lasers operate at fundamental transverse mode due to a scattering loss mechanism. Threshold currents of 18 mA and stable single transverse mode operating at high currents are obtained
Direct measurement of the carrier leakage in an InGaAsP/InP laser
Carrier leakage over the heterobarrier in an InGaAsP/InP laser is measured directly in a laser-bipolar-transistor structure. Experimental results indicate a significant amount of carrier leakage under normal laser operating conditions
Low threshold InGaAsP terrace mass transport laser on semi-insulating substrate
Very low threshold InGaAsP terrace lasers on semi-insulating (SI) InP substrate have been fabricated using the mass transport technique. The fabrication process involves a single-step liquid phase epitaxial (LPE) growth followed by a mass transport of InP at ~675 °C in the presence of an InP cover wafer. Lasers operating in the fundamental transverse mode with smooth far-field patterns and threshold currents as low as 9.5 mA have been obtained
Very low threshold InGaAsP mesa laser
Very low threshold currents InGaAsP/InP terrace mesa (T-ME) lasers with an unpassivated surface have been fabricated on semi-insulating (SI) InP substrates. Fabrication of the lasers involves a single-step liquid phase epitaxial (LPE) growth and a simple etching process. Lasers operating in the fundamental transverse mode with threshold currents as low as 6.3 mA (for a cavity length of 250 ÎĽm) have been obtained. Comparison between the unpassivated lasers and those passivated using the mass transport technique is described
Correlation and prediction of dynamic human isolated joint strength from lean body mass
A relationship between a person's lean body mass and the amount of maximum torque that can be produced with each isolated joint of the upper extremity was investigated. The maximum dynamic isolated joint torque (upper extremity) on 14 subjects was collected using a dynamometer multi-joint testing unit. These data were reduced to a table of coefficients of second degree polynomials, computed using a least squares regression method. All the coefficients were then organized into look-up tables, a compact and convenient storage/retrieval mechanism for the data set. Data from each joint, direction and velocity, were normalized with respect to that joint's average and merged into files (one for each curve for a particular joint). Regression was performed on each one of these files to derive a table of normalized population curve coefficients for each joint axis, direction, and velocity. In addition, a regression table which included all upper extremity joints was built which related average torque to lean body mass for an individual. These two tables are the basis of the regression model which allows the prediction of dynamic isolated joint torques from an individual's lean body mass
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