290 research outputs found
Analysis of signal to noise enhancement using a highly selective modulation tracking filter
Experiments are reported which utilize photodielectric effects in semiconductor loaded superconducting resonant circuits for suppressing noise in RF communication systems. The superconducting tunable cavity acts as a narrow band tracking filter for detecting conventional RF signals. Analytical techniques were developed which lead to prediction of signal-to-noise improvements. Progress is reported in optimization of the experimental variables. These include improved Q, new semiconductors, improved optics, and simplification of the electronics. Information bearing signals were passed through the system, and noise was introduced into the computer model
Emergy Evaluations of Denmark and Danish Agriculture Assessing the Limits of Agricultural Systems to Power Society
As the process of industrialization has run its course over the twentieth century, the relative importance of agriculture as an economic activity and a means of cultural sustenance for nations has declined dramatically. In this thesis, a historical ecological-economic perspective offers insights into both the causes and effects of Danish agriculture's decline in economic importance relative to the economy of Denmark as a whole. Emergy evaluations were made of the national economy and agricultural subsystem of Denmark for the years 1936, 1970 and 1999. Emergy is defined as all the available energy that was used in the work of making a product and expressed in units of one type of energy (Odum, 1996). In total, six separate emergy analyses were performed. By quantifying the emergy requirements of both a national agricultural system and the economy within which this system is nested, the analysis highlights the changing relationship of these two systems over a temporal scale of 63 years.
The ecological sustainability of the studied systems is assessed through the calculation of emergy-based indices and ratios. In accordance with emergy theory, ecological sustainability is considered to be a function of the dependence of a system on renewable emergy, the degree to which the system depends on imported emergy, and the overall load that the system places on the environment. The analysis indicates that as the national economy of Denmark evolved to rely more on the use of non-renewable emergy and on emergy appropriated through trade to stimulate economic activity and to generate wealth, its sustainability declined, and the importance of the Danish agricultural system to the national economy subsided. While the total amount of emergy supporting the economy of Denmark over the period studied increased substantially, the total emergy supporting agriculture remained relatively constant. Furthermore, though the emergy signature and thermodynamic efficiencies of Danish agricultural production changed significantly, the total emergy required for production fluctuated little. This implies that the thermodynamically optimal level of emergy investment to agricultural production from society may fall within a range that is essentially fixed. Finally, the analysis draws attention to the fact that because agricultural systems are coupled to renewable emergy flows that are limited in the amount of work processes that they can power, agricultural systems register small net emergy yields, thus, agriculture is not likely to be a primary motive force in an economy with access to storages of fossil and other fuels that provide large net emergy yields
Scattering of the Radiation Field of a Loop Antenna by a Conducting Cylinder Immersed in a Cold Plasma
A Systematic Review of the Efficacy of Cognitive Stimulation Therapy (CST) on Quality of Life in Persons with Dementia
Quality of life (QoL) is an established outcome measure of patients with dementia and is strongly influenced by an individual\u27s environment and mood. While there are many outcomes that can be examined with Cognitive stimulation therapy (CST) interventions, this systematic review focused on quality of life
A Randomized Controlled Trial on the Effects of Yoga on Stress Reactivity in 6th Grade Students
There is an increasing interest in developing school programs that improve the ability of children to cope with psychosocial stress. Yoga may be an appropriate intervention as it has demonstrated improvements in the ability of children to manage psychosocial stress. Yoga is thought to improve the control of reactivity to stress via the regulation of the autonomic nervous system. The current study examined the effects of yoga compared to a physical education class on physiological response (blood pressure (BP) and heart rate (HR)) to behavioral stressor tasks (mental arithmetic and mirror tracing tasks). Data analysis of BP and HR was performed using a 2 × 2 × 4 repeated measures ANOVA (time × group × stressor time points). 30 (17 male) 6th graders participated in the study. Yoga did not provide significant differences in stress reactivity compared to a physical education class (group × time: systolic (F(1,28)=.538, P=.470); diastolic (F(1,28)=.1.061, P=.312); HR (F(1,28)=.401, P=.532)). The lack of significant differences may be due to the yoga intervention failing to focus on stress management and/or the stressor tasks not adequately capturing attenuation of stressor response
Yoga and Emotion Regulation in High School Students: A Randomized Controlled Trial
Middle adolescents (15–17 years old) are prone to increased risk taking and emotional instability. Emotion dysregulation contributes to a variety of psychosocial difficulties in this population. A discipline such as yoga offered during school may increase emotion regulation, but research in this area is lacking. This study was designed to evaluate the impact of a yoga intervention on the emotion regulation of high school students as compared to physical education (PE). In addition, the potential mediating effects of mindful attention, self-compassion, and body awareness on the relationship between yoga and emotion regulation were examined. High school students were randomized to participate in a 16-week yoga intervention (n=19) or regular PE (n=18). Pre-post data analyses revealed that emotion regulation increased significantly in the yoga group as compared to the PE group (F (1,32) = 7.50, p=.01, and eta2 = .19). No significant relationship was discovered between the changes in emotion regulation and the proposed mediating variables. Preliminary results suggest that yoga increases emotion regulation capacities of middle adolescents and provides benefits beyond that of PE alone
Substantial carbon loss respired from a corn-soybean agroecosystem highlights the importance of careful management as we adapt to changing climate
Understanding agroecosystem carbon (C) cycle response to climate change and management is vital for maintaining their long-term C storage. We demonstrate this importance through an in-depth examination of a ten-year eddy covariance dataset from a corn-corn-soybean crop rotation grown in the Midwest United States. Ten-year average annual net ecosystem exchange (NEE) showed a net C sink of -0.39 Mg C ha-1 yr-1. However, NEE in 2014 and 2015 from the corn ecosystem was 3.58 and 2.56 Mg C ha-1 yr-1, respectively. Most C loss occurred during the growing season, when photosynthesis should dominate and C fluxes should reflect a net ecosystem gain. Partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (ER) showed this C \u27burp\u27 was driven by higher ER, with a 51% (2014) and 57% (2015) increase from the ten-year average (15.84 Mg C ha-1 yr-1). GPP was also higher than average (16.24 Mg C ha-1 yr-1) by 25% (2014) and 37% (2015), but this was not enough to offset the C emitted from ER. This increased ER was likely driven by enhanced soil microbial respiration associated with ideal growing season climate, substrate availability, nutrient additions, and a potential legacy effect from drought
Creative and Stylistic Devices Employed by Children During a Storybook Narrative Task: A Cross-Cultural Study
Purpose: The purpose of this study was to analyze the effects of culture on the creative and stylistic features children employ when producing narratives based on wordless picture books.
Method: Participants included 60 first- and second-grade African American, Latino American, and Caucasian children. A subset of narratives based on wordless picture books collected as part of a larger study was coded and analyzed for the following creative and stylistic conventions: organizational style (topic centered, linear, cyclical), dialogue (direct, indirect), reference to character relationships (nature, naming, conduct), embellishment (fantasy, suspense, conflict), and paralinguistic devices (expressive sounds, exclamatory utterances).
Results: Many similarities and differences between ethnic groups were found. No significant differences were found between ethnic groups in organizational style or use of paralinguistic devices. African American children included more fantasy in their stories, Latino children named their characters more often, and Caucasian children made more references to the nature of character relationships.
Conclusion: Even within the context of a highly structured narrative task based on wordless picture books, culture influences children’s production of narratives. Enhanced understanding of narrative structure, creativity, and style is necessary to provide ecologically valid narrative assessment and intervention for children from diverse cultural backgrounds
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