Logarithmic circuit with wide dynamic range

A circuit deriving an output voltage that is proportional to the logarithm of a dc input voltage susceptible to wide variations in amplitude includes a constant current source which forward biases a diode so that the diode operates in the exponential portion of its voltage versus current characteristic, above its saturation current. The constant current source includes first and second, cascaded feedback, dc operational amplifiers connected in negative feedback circuit. An input terminal of the first amplifier is responsive to the input voltage. A circuit shunting the first amplifier output terminal includes a resistor in series with the diode. The voltage across the resistor is sensed at the input of the second dc operational feedback amplifier. The current flowing through the resistor is proportional to the input voltage over the wide range of variations in amplitude of the input voltage

The two stories of the habitus/structure relation and the riddle of reflexivity: A meta‐theoretical reappraisal

This article argues that two key puzzles arising from the theories of Bourdieu are inter-related. One is the question of how Bourdieu analyses the relationship between structure and habitus, and the other is the place of reflexivity in Bourdieu's work. We contend that it is only by carefully analysing Bourdieu's theoretical structure to grasp the relationship between these elements that one can understand whether or not his work offers useful resources for analysing the relation between routine action and self-reflection. This paper argues that there are two narrations of the structure/habitus relation in Bourdieu's work, and that the concept of self-reflective subjectivity is a residual element of the first narration and does not appear in the second. We then contend that this residual and under-developed concept of self-reflective subjectivity should not be confused with Bourdieu's analysis of epistemic reflexivity. These moves allow us to contribute to ongoing debates about the relation between routine action and self-reflection by arguing that the concept of the “reflexive habitus” – which some have argued is characteristic of social agents in high/late modernity – is both conceptually confused and is not a logical extension of Bourdieu's theories. In this way we try to clear the ground for more productive ways of thinking about routine action and self-reflection

Teacher and School Characteristics: Predictors of Student Achievement in Georgia Public Schools

Student achievement of fifth-grade students in 106 Georgia public schools in CRCT reading and mathematics was examined as a function of five characteristics of teachers and schools. The five independent variables used as predictors of CRCT scores were Title I status, teachers’ education level, teachers’ average years of experience, class size, and computer to student ratio. Designation as a Title I school was the strongest predictor of student achievement. When compared to non-Title I schools, Title I school status resulted in a higher percentage of students meeting CRCT standards in both reading and math and a lower percentage of students exceeding standards in both reading and mathematics. However, Title I school status also resulted in a higher percentage of students meeting standards on both the CRCT reading and mathematics. Class size seemed to have very little relationship to the overall achievement of fifth-grade students. Teacher quality revealed mixed, though generally positive results when correlated with student achievement. Even though Title I designation is indicative of positive outcomes for CRCT scores, these positive outcomes do not hold for every predictor

Stimulating a Great Lakes Coastal Wetland Seed Bank using Portable Cofferdams: Implications for Habitat Rehabilitation

Coastal wetland seed banks exposed by low lake levels or through management actions fuel the reestablishment of emergent plant assemblages (i.e., wetland habitat) critical to Great Lakes aquatic biota. This project explored the effectiveness of using portable, water-filled cofferdams as a management tool to promote the natural growth of emergent vegetation from the seed bank in a Lake Erie coastal wetland. A series of dams stretching approximately 450 m was installed temporarily to isolate hydrologically a 10-ha corner of the Crane Creek wetland complex from Lake Erie. The test area was dewatered in 2004 to mimic a low-water year, and vegetation sampling characterized the wetland seed bank response at low, middle, and high elevations in areas open to and protected from bird and mammal herbivory. The nearly two-month drawdown stimulated a rapid seed-bank-driven response by 45 plant taxa. Herbivory had little effect on plant species richness, regardless of the location along an elevation gradient. Inundation contributed to the replacement of immature emergent plant species with submersed aquatic species after the dams failed and were removed prematurely. This study revealed a number of important issues that must be considered for effective long-term implementation of portable cofferdam technology to stimulate wetland seed banks, including duration of dewatering, product size, source of clean water, replacement of damaged dams, and regular maintenance. This technology is a potentially important tool in the arsenal used by resource managers seeking to rehabilitate the functions and values of Great Lakes coastal wetland habitats

Fish Assemblages, Connectivity, and Habitat Rehabilitation in a Diked Great Lakes Coastal Wetland Complex

Fish and plant assemblages in the highly modified Crane Creek coastal wetland complex of Lake Erie were sampled to characterize their spatial and seasonal patterns and to examine the implications of the hydrologic connection of diked wetland units to Lake Erie. Fyke netting captured 52 species and an abundance of fish in the Lake Erie–connected wetlands, but fewer than half of those species and much lower numbers and total masses of fish were captured in diked wetland units. Although all wetland units were immediately adjacent to Lake Erie, there were also pronounced differences in water quality and wetland vegetation between the hydrologically isolated and lake-connected wetlands. Large seasonal variations in fish assemblage composition and biomass were observed in connected wetland units but not in disconnected units. Reestablishment of hydrologic connectivity in diked wetland units would allow coastal Lake Erie fish to use these vegetated habitats seasonally, although connectivity does appear to pose some risks, such as the expansion of invasive plants and localized reductions in water quality. Periodic isolation and drawdown of the diked units could still be used to mimic intermediate levels of disturbance and manage invasive wetland vegetation

A depolarization and attenuation experiment using the COMSTAR and CTS satellites

Monthly statistical data are presented on ground rainfall rate and attenuation of satellite downlinks at 11.7 GHz, 19.04 GHz, and 28.56 GHz and on cross-polarization isolation at 11.7 GHz. Regression equations for relating isolation to attenuation, attenuation to rain rate, and attenuation at one frequency to attenuation at another frequency are also included. Longer-term statistics are also presented and discussed

A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment

A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems

The Experience of Mental Health Service Use For African American Mothers and Youth

Little is known about African American families’ experiences with mental health services. A purposive sample of 40 dyads of African American youth (aged 13 to 19) and their mothers participated in a cross-sectional qualitative research design using semi-structured interviews that elicited information about their past experiences and satisfaction with mental health services. Though rarely received, group and family therapy were perceived favorably. However, both mothers and youth reported dissatisfaction centered on medication and lack of professionalism, confidentiality, and concern by providers. The failure of mental health services providers to meet basic standards of quality and professionalism may explain the low rate of service use by African Americans

Development of the Infant Gut Microbiome Predicts Temperament Across the First Year of Life

Perturbations to the gut microbiome are implicated in altered neurodevelopmental trajectories that may shape life span risk for emotion dysregulation and affective disorders. However, the sensitive periods during which the microbiome may influence neurodevelopment remain understudied. We investigated relationships between gut microbiome composition across infancy and temperament at 12 months of age. In 67 infants, we examined if gut microbiome composition assessed at 1–3 weeks, 2, 6, and 12 months of age was associated with temperament at age 12 months. Stool samples were sequenced using the 16S Illumina MiSeq platform. Temperament was assessed using the Infant Behavior Questionnaire-Revised (IBQ-R). Beta diversity at age 1–3 weeks was associated with surgency/extraversion at age 12 months. Bifidobacterium and Lachnospiraceae abundance at 1–3 weeks of age was positively associated with surgency/extraversion at age 12 months. Klebsiella abundance at 1–3 weeks was negatively associated with surgency/extraversion at 12 months. Concurrent composition was associated with negative affectivity at 12 months, including a positive association with Ruminococcus-1 and a negative association with Lactobacillus. Our findings support a relationship between gut microbiome composition and infant temperament. While exploratory due to the small sample size, these results point to early and late infancy as sensitive periods during which the gut microbiome may exert effects on neurodevelopment