586 research outputs found
Development of microcomputer-based mental acuity tests for repeated-measures studies
The purpose of this report is to detail the development of the Automated Performance Test System (APTS), a computer battery of mental acuity tests that can be used to assess human performance in the presence of toxic elements and environmental stressors. There were four objectives in the development of APTS. First, the technical requirements for developing APTS followed the tenets of the classical theory of mental tests which requires that tests meet set criteria like stability and reliability (the lack of which constitutes insensitivity). To be employed in the study of the exotic conditions of protracted space flight, a battery with multiple parallel forms is required. The second criteria was for the battery to have factorial multidimensionality and the third was for the battery to be sensitive to factors known to compromise performance. A fourth objective was for the tests to converge on the abilities entailed in mission specialist tasks. A series of studies is reported in which candidate APTS tests were subjected to an examination of their psychometric properties for repeated-measures testing. From this work, tests were selected that possessed the requisite metric properties of stability, reliability, and factor richness. In addition, studies are reported which demonstrate the predictive validity of the tests to holistic measures of intelligence
Spectral methods in image segmentation: a combined approach
Indexado ISIGrouping and segmentation of images remains a challenging problem in computer vision. Recently, a number of authors have demonstrated a good performance on this task using spectral methods that are based on the eigensolution of a similarity matrix. In this paper, we implement a variation of the existing methods that combines aspects from several of the best-known eigenvector segmentation algorithms to produce a discrete optimal solution of the relaxed continuous eigensolution
Spreading of a density front in the K\"untz-Lavall\'ee model of porous media
We analyze spreading of a density front in the K\"untz-Lavall\'ee model of
porous media. In contrast to previous studies, where unusual properties of the
front were attributed to anomalous diffusion, we find that the front evolution
is controlled by normal diffusion and hydrodynamic flow, the latter being
responsible for apparent enhancement of the front propagation speed. Our
finding suggests that results of several recent experiments on porous media,
where anomalous diffusion was reported based on the density front propagation
analysis, should be reconsidered to verify the role of a fluid flow
Measurement of Volumetric Flow
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135278/1/jum200625101305.pd
Cavitation clouds created by shock scattering from bubbles during histotripsy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98656/1/JAS001888.pd
Volumetric Blood Flow in Transjugular Intrahepatic Portosystemic Shunt Revision Using 3‐Dimensional Doppler Sonography
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135560/1/jum2015342257.pd
Control of the diffracted response of a metallic Wire Array with Double Period: Experimental Demonstration
In recent papers, it has been theoretically shown that by using dual-period wire gratings, it is possible to control the relative efficiencies of the diffracted orders, regardless of the wires’ material, incident polarization and wavelength. In this Letter, we experimentally demonstrate, for the first time, that by appropriately choosing the geometrical parameters of a nanometric periodic structure, it is possible to control the optical response in the visible range. We show examples of nanostructures designed to cancel out or to intensify a particular diffraction order. Such nanostructures allow a broad control over the directionality and the intensity of the diffracted light, which makes them useful for applications such as highly directional optical nanoantennas and photonic multiplexers
Sonographic Evaluation of Early‐Stage Breast Cancers That Undergo Neoadjuvant Chemotherapy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135555/1/jum2005247885.pd
Three‐Dimensional Sonographic Measurement of Blood Volume Flow in the Umbilical Cord
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135361/1/jum201231121927.pd
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