Multiple Measurement Points Research Articles

Cerebral oxygenation changes in the prefrontal cortex: Effects of age and gender

Multi-channel near-infrared spectroscopy (NIRS) is an optical method, which allows non-invasive in vivo measurements of changes in the concentration of oxygenated (O 2Hb) and deoxygenated (HHb) hemoglobin in living brain tissue, simultaneously from multiple measurement points. In the present study, 44 young and 42 elderly subjects were investigated by means of multi-channel NIRS (optical topography) during performance of the verbal fluency task (VFT). The aim of the study was to analyze the effects of the subjects’ age and gender on functional brain activation during this cognitive task. In summary, the results clearly show that the VFT activated the left and right dorsolateral prefrontal cortex (increases in O 2Hb and more localized decreases in HHb), with an obvious left-hemispheric dominance. The elderly subjects generally exhibited less activation and no left hemispheric lateralization effect. In contrast to a previous study, we did not find a clear influence of the subjects’ gender on the brain activation pattern.

On Design for IDDQ-Based Diagnosability of CMOS Circuits Using Multiple Power Supplies

This paper presents a novel approach to improving the IDDQ-based diagnosability of a CMOS circuit by dividing the circuit into independent partitions and using a separate power supply for each partition. This technique makes it possible to implement multiple IDDQ measurement points, resulting in improved IDDQ-based diagnosability. The paper formalizes the problem of partitioning a circuit for this purpose and proposes optimal and heuristic based solutions. The effectiveness of the proposed approach is demonstrated through experimental results.

Recent developments in laser Doppler velocimeter for landmine detection

This presentation discusses laser Doppler vibrometer (LDV) instruments developed by MetroLaser that are specifically tailored to work with the acoustic/seismic technique for buried landmine detection and data obtained with these systems under various field conditions. The first system is a simple and rugged diode laser LDV that measures a single point on the ground. Multiple diode systems or a scanning mirror placed in front of the diode LDV are some of the strategies used to measure multiple points. The second system is a multi-beam LDV that uses a single YAG laser and diffraction optical elements to create an array of laser beams and thus multiple measurement points on the ground. The data obtained with LDV consist of velocity profiles at each point of the surface illuminated by each of the beams. By interrogating multiple points (with multiple vibrometers or with a multi-beam vibrometer) the system can ascertain with high probability the presence of a buried landmine. The systems exhibit a velocity resolution of about 1 micron per second, which is suitable for landmine detection. Low-frequency (100 kHz) carrier is employed in the multi-beam system to further enhance its performance with the acoustic/seismic technique.

Pushing the Quality Envelope: A New Outcomes Management System

This article is based on the authors' experience in designing and implementing outcomes management systems for large managed care organizations. Topics addressed include design of instruments, use of cost-effective technology, development of computerized decision-support tools, and methods for case-mix adjustment. The case-mix-adjustment models are based on a data repository of several thousand treatment cases with multiple measurement points across the course of treatment. Data from controlled and field studies are described. These data suggest that the outcomes management methods outlined in this article can result in significantly improved clinical outcomes and a more rational allocation of behavioral health care resources.

Prevalence of tobacco use in Switzerland in the 1990's--estimation of consumption trends based on 2 methods

Smoking prevalence rates in Switzerland in the 1990s++ have been estimated from Perma data, which have been available quarterly since 1991, as well as from the data of the first and second Swiss Health Surveys, conducted in 1992/93 and 1997. Both sources--each providing data on more than 10,000 respondents--have been large-scale surveys that have used different but complementary survey designs. The probabilistic sampling design of the Health Surveys assures representative findings; the Perma data, although obtained through a non-probabilistic sampling design, permits trend analysis as Perma uses multiple measurement points and therefore time-series methodology can be applied. Both Perma and the Health Surveys yielded approximately the same prevalence of 37% male smokers in 1992/93 and 39% in 1997. For females Perma gave 4% higher prevalence rates than the Health Surveys (Surveys 1992/93: 24%; 1997: 31%). For both sexes the increase in total smoking prevalence was accounted for mainly by adolescents and young adults. Whereas the Surveys showed an increase from 29% to 41% (18% to 39%) in males (females) aged 15 to 19 years, the corresponding increase derived from Perma was 50% less. Except for this youngest age-group, differences between the methods remained within standard statistical norms. There is no doubt, however, that smoking in adolescents increased between 1992/93 and 1997.

Development of digital particle imaging velocimetry for use in turbomachinery

Digital Particle Imaging Velocimetry (DPIV) is a powerful measurement technique, which can be used as an alternative or complementary approach to Laser Doppler Velocimetry (LDV) in a wide range of research applications. The instantaneous planar velocity measurements obtained with PIV make it an attractive technique for use in the study of the complex flow fields encountered in turbomachinery. The ability to acquire multiple measurement points of comparable accuracy to LDV results in reduced runtime and enables the study of both transient and steady state flow phenomena. Many of the same issues encountered in the application of LDV to rotating machinery apply in the application of PIV. Techniques for optical access, light sheet delivery, CCD camera technology and particulate seeding are discussed. Results from the successful application of the PIV technique to both the blade passage region of a transonic axial compressor and the diffuser region of a high speed centrifugal compressor are presented. Both instantaneous and time-averaged flow fields were obtained. The 95% confidence intervals for the velocity estimates were also determined.

On the multiple microphone method for measuring in-duct acoustic properties in the presence of mean flow

Nowadays, the two-microphone method is accepted as the standard as specified in ASTM E1050-90 for measuring in-duct acoustic properties. However, research results on using the least square method with multiple measurement points and broadband excitation have been reported for enhancing the frequency response of the two-microphone method. In this paper, the effects of varying the relative measurement positions on errors in the estimation of the acoustic quantities is studied for the multiple microphone method. Both the theoretical and experimental results show that, among possible sensor positioning configurations, the equidistant positioning of sensors yields the smallest error within the effective measurement frequency range. In addition, it is noted that the measurement accuracy can be increased and the effective frequency range can be widened by increasing the number of equidistant sensors. Measurement examples are shown and the results support the findings.

The Course of Intellectual Development in Preterm and Fullterm Children: An 8-year Longitudinal Study

A total of 55 preterm children born at low to moderate risk and a comparison group of 100 healthy fullterm children were studied until they reached 8 years of age. Perinatal biomedical data and environmental data were considered as potential contributors to developmental outcome. The Budapest Binet intelligence quotients (IQs) were used as outcome measures. The mean IQs for both groups fell within the normal range at each measurement point. However, the differential patterns of IQ development in the preterm and term group underscore the significance of the age variable. Instead of a gradually declining impact of prematurity, the age effect resulted in a complex pattern. The considerable intra-group variability within the preterm group and the correlates of outcome suggest that biological hazards related to birth may have subtle long-term influences. Variables tapping the quality of home environment, however, clearly outweighed the perinatal risk factors in their ability to predict long-term outcomes. The results suggest a transaction between the two spheres of contributing factors. Long-term follow-up studies with multiple measurement points are essential if we are to understand the developmental implications of premature birth.

Calibration of a Dual‐Energy Gamma Radiation System for Multiple Point Measurements in a Soil

A method is described to experimentally determine the calibration constants for gamma‐ray attenuation at multiple measurement points along a soil column as needed to simultaneously determine volumetric water content and dry bulk density at each of these points during subsequent experiments. Calibration constants for the soil solids, for both Cs‐137 and Am‐241, are defined as the product of the respective mass attenuation coefficients and the thickness of the soil through which the gamma radiation beam traverses. Calibration constants for water are similarly defined but include the additional term of water density. The calibration technique corrects for low energy Cs‐137 pulses present in the Am‐241 window and for resolving time. Although calibration constants are determined for each measurement point, the technique requires knowledge only of the initial average dry bulk density in the soil column and not at every point. The calibration constants and initial dry bulk density value for each measurement point are determined by an iteration procedure. Errors stemming from changes in the sources‐soil column‐detector configuration and/or pathlength when measuring at different points are therefore negated.