Nanosecond Peak Detect And Hold Circuit With Adjustable Dynamic Range

This article presents a novel peak detect and hold (PDH) circuit for the measurement of the peak voltage of electromagnetic-field probes. These probes are used to capture the fields generated by electrostatic discharge (ESD) events in nongrounded portable devices. Therefore, a circuit combining small size, low power consumption, and nanosecond operation is needed. A topology using a discrete bipolar transistor structure with operational transconductance amplifier (OTA) and common-base storage capacitor charge control optimally meets the requirements. The circuit performance is demonstrated for different bias point settings. The error between the captured value and the actual pulse peak value is shown as a function of rise time, pulse length, amplitude, and bias settings. A comparison with the literature shows unmatched performance with respect to speed and power consumption. Using the bias settings, the PDH circuit can be adjusted to the sensor\u27s frequency response to minimize power consumption in a multichannel system containing sensors of different bandwidths

法政大学図書館一〇〇年史 : 第一編 図書館通史 : 第九章 三キャンパス体制への対応 二、工学部図書館の歩み

Lower extremity musculoskeletal injuries are common, complex, and costly problems. Literature supports associations between static foot structure and dynamic foot function, as well as between overuse injury and demographic characteristics. Previous studies failed to provide a comprehensive biomechanical foot characteristics of at-risk military personnel. In this study, foot structure, function, and arch height flexibility (AHF) were objectively measured in 1090 incoming cadets (16.3% female, mean age of 18.5years and BMI of 24.5kg/

Body size and walking cadence affect lower extremity joint power in children's gait

Obese children move less and with greater difficulty than normal-weight counterparts but expend comparable energy. Increased metabolic costs have been attributed to poor biomechanics but few studies have investigated the influence of obesity on mechanical demands of gait. This study sought to assess three-dimensional lower extremity joint powers in two walking cadences in 28 obese and normal-weight children. 3D-motion analysis was conducted for five trials of barefoot walking at self-selected and 30% greater than self-selected cadences. Mechanical power was calculated at the hip, knee, and ankle in sagittal, frontal and transverse planes. Significant group differences were seen for all power phases in the sagittal plane, hip and knee power at weight acceptance and hip power at propulsion in the frontal plane, and knee power during mid-stance in the transverse plane. After adjusting for body weight, group differences existed in hip and knee power phases at weight acceptance in sagittal and frontal planes, respectively. Differences in cadence existed for all hip joint powers in the sagittal plane and frontal plane hip power at propulsion. Frontal plane knee power at weight acceptance and sagittal plane knee power at propulsion were significantly different between cadences. Larger joint powers in obese children contribute to difficulty performing locomotor tasks, potentially decreasing motivation to exercise

Argonne National Laboratory Reports

The solution of the general nonlinear programming problem by means of a subroutine called VMCON is described. VMCON uses an algorithm that solves a sequence of positive-definite quadratic programming sub-problems. Each solution determines a direction in which a one-dimensional minimization is performed. In developing this code, changes in the original implementation were made to make the program easier to use and maintain and to incorporate some recently developed LINPACK subprograms. The current implementation contains extensive in-line documentation; an interface subroutine, VMCON1, with a simplified calling sequence; and print options to aid the user in interpreting results

Elevated carbon dioxide and ozone have weak, idiosyncratic effects on herbivorous forest insect abundance, species richness, and community composition

Elevated concentrations of carbon dioxide and tropospheric ozone pose important threats to the abundance, diversity, and composition of forest arthropod communities. In turn, modification of arthropod communities may alter forest health, productivity, and ecosystem services. We studied the independent and interactive effects of elevated CO2 (eCO2) and elevated O3 (eO3) on the abundance, species richness, and community composition of herbivorous arthropods in stands of trembling aspen and paper birch at the Aspen Free Air CO2Enrichment (FACE) site in northern Wisconsin, USA. We conducted timed, visual surveys of canopy arthropods during each of the summers of 2005, 2006, and 2007. We examined 26 983 arthropods on aspen and 8344 arthropods on birch across the fumigation treatments. Elevated CO2 and eO3 had species-specific and temporally variable (i.e. idiosyncratic) effects on aspen and birch arthropod abundance and species richness. Weak, idiosyncratic effects of eCO2 and eO3 on herbivorous arthropod abundance and species richness did not significantly alter aspen arthropod community composition but occasionally altered birch insect community composition. Few interactive effects of CO2 and O3were observed. Growing evidence suggests that the effects of eCO2 and eO3 on communities of insects are difficult to predict because responses are generally weak and species- and time-specific. Although studies to date suggest that impacts of future atmospheres on insect community metrics are likely to be minimal, the possibility remains that effects on particularly important or susceptible species may cascade to alter trophic interactions and, ultimately, ecosystem processes

Effects of pediatric obesity on joint kinematics and kinetics during 2 walking cadences

Objective: To determine whether differences existed in lower-extremity joint biomechanics during self-selected walking cadence (SW) and fast walking cadence (FW) in overweight- and normal-weight children.---------- Design: Survey.---------- Setting: Institutional gait study center.---------- Participants: Participants (N=20; mean age ± SD, 10.4±1.6y) from referred and volunteer samples were classified based on body mass index percentiles and stratified by age and sex. Exclusion criteria were a history of diabetes, neuromuscular disorder, or recent lower-extremity injury.---------- Main Outcome Measures: Sagittal, frontal, and transverse plane angular displacements (degrees) and peak moments (newton meters) at the hip, knee, and ankle joints.---------- Results: The level of significance was set at P less than .008. Compared with normal-weight children, overweight children had greater absolute peak joint moments at the hip (flexor, extensor, abductor, external rotator), the knee (flexor, extensor, abductor, adductor, internal rotator), and the ankle (plantarflexor, inverter, external/internal rotators). After including body weight as a covariate, overweight children had greater peak ankle dorsiflexor moments than normal-weight children. No kinematic differences existed between groups. Greater peak hip extensor moments and less peak ankle inverter moments occurred during FW than SW. There was greater angular displacement during hip flexion as well as less angular displacement at the hip (extension, abduction), knee (flexion, extension), and ankle (plantarflexion, inversion) during FW than SW.---------- Conclusions: Overweight children experienced increased joint moments, which can have long-term orthopedic implications and suggest a need for more nonweight-bearing activities within exercise prescription. The percent of increase in joint moments from SW to FW was not different for overweight and normal-weight children. These findings can be used in developing an exercise prescription that must involve weight-bearing activity