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Search Results: 1 - 10 of 85668 matches for " W. Franklin "
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Forest Plant and Bird Communities in the Lau Group, Fiji
Janet Franklin,David W. Steadman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0015685
Abstract: We examined species composition of forest and bird communities in relation to environmental and human disturbance gradients on Lakeba (55.9 km2), Nayau (18.4 km2), and Aiwa Levu (1.2 km2), islands in the Lau Group of Fiji, West Polynesia. The unique avifauna of West Polynesia (Fiji, Tonga, Samoa) has been subjected to prehistoric human-caused extinctions but little was previously known about this topic in the Lau Group. We expected that the degree of human disturbance would be a strong determinant of tree species composition and habitat quality for surviving landbirds, while island area would be unrelated to bird diversity.
Some classes of minimally almost periodic topological groups
W. W. Comfort,Franklin R. Gould
Mathematics , 2014,
Abstract: Classes SSGP(n)(n < \omega) of topological groups are defined, and the class-theoretic inclusions SSGP(n) \subseteq SSGP(n+1) \subseteq m.a.p. are established and shown proper. These classes are investigated with respect to the properties normally studied by topologists (products, quotients, passage to dense subgroups, and the like). In passing the authors establish the presence of the SSGP(1) or SSGP(2) property in many of the early examples in the literature of abelian m.a.p. groups.
Generalization in Adaptation to Stable and Unstable Dynamics
Abdelhamid Kadiallah, David W. Franklin, Etienne Burdet
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045075
Abstract: Humans skillfully manipulate objects and tools despite the inherent instability. In order to succeed at these tasks, the sensorimotor control system must build an internal representation of both the force and mechanical impedance. As it is not practical to either learn or store motor commands for every possible future action, the sensorimotor control system generalizes a control strategy for a range of movements based on learning performed over a set of movements. Here, we introduce a computational model for this learning and generalization, which specifies how to learn feedforward muscle activity in a function of the state space. Specifically, by incorporating co-activation as a function of error into the feedback command, we are able to derive an algorithm from a gradient descent minimization of motion error and effort, subject to maintaining a stability margin. This algorithm can be used to learn to coordinate any of a variety of motor primitives such as force fields, muscle synergies, physical models or artificial neural networks. This model for human learning and generalization is able to adapt to both stable and unstable dynamics, and provides a controller for generating efficient adaptive motor behavior in robots. Simulation results exhibit predictions consistent with all experiments on learning of novel dynamics requiring adaptation of force and impedance, and enable us to re-examine some of the previous interpretations of experiments on generalization.
Visual Feedback Is Not Necessary for the Learning of Novel Dynamics
David W. Franklin, Udell So, Etienne Burdet, Mitsuo Kawato
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0001336
Abstract: Background When learning to perform a novel sensorimotor task, humans integrate multi-modal sensory feedback such as vision and proprioception in order to make the appropriate adjustments to successfully complete the task. Sensory feedback is used both during movement to control and correct the current movement, and to update the feed-forward motor command for subsequent movements. Previous work has shown that adaptation to stable dynamics is possible without visual feedback. However, it is not clear to what degree visual information during movement contributes to this learning or whether it is essential to the development of an internal model or impedance controller. Methodology/Principle Findings We examined the effects of the removal of visual feedback during movement on the learning of both stable and unstable dynamics in comparison with the case when both vision and proprioception are available. Subjects were able to learn to make smooth movements in both types of novel dynamics after learning with or without visual feedback. By examining the endpoint stiffness and force after learning it could be shown that subjects adapted to both types of dynamics in the same way whether they were provided with visual feedback of their trajectory or not. The main effects of visual feedback were to increase the success rate of movements, slightly straighten the path, and significantly reduce variability near the end of the movement. Conclusions/Significance These findings suggest that visual feedback of the hand during movement is not necessary for the adaptation to either stable or unstable novel dynamics. Instead vision appears to be used to fine-tune corrections of hand trajectory at the end of reaching movements.
Fluctuations in Student Understanding of Newton's 3rd Law
Jessica W. Clark,Eleanor C. Sayre,Scott V. Franklin
Physics , 2010, DOI: 10.1063/1.3515171
Abstract: We present data from a between-student study on student response to questions on Newton's Third Law given throughout the academic year. The study, conducted at Rochester Institute of Technology, involved students from the first and third of a three-quarter sequence. Construction of a response curve reveals subtle dynamics in student learning not captured by simple pre/post testing. We find a a significant positive effect from direct instruction, peaking at the end of instruction on forces, that diminishes by the end of the quarter. Two quarters later, in physics III, a significant dip in correct response occurs when instruction changes from the vector quantities of electric forces and fields to the scalar quantity of electric potential. Student response rebounds to its initial values, however, once instruction returns to the vector-based topics involving magnetic fields.
Effects of Academic Stress and Perceived Social Support on the Psychological Wellbeing of Adolescents in Ghana  [PDF]
Franklin N. Glozah
Open Journal of Medical Psychology (OJMP) , 2013, DOI: 10.4236/ojmp.2013.24022
Abstract: The purpose of this study was to examine how academic stress and perceived social support influence the psychological wellbeing of Senior High School students in Ghana. Two hundred and twenty six male and female students participated. The general health questionnaire, student life-stress inventory and perceived social support from family and friends scales were used to assess psychological wellbeing, academic stress and perceived social support respectively. The results indicated that perceived social support buffered the effects of academic stress on psychological wellbeing. Girls reported higher scores on perceived social support but reported more depression. Boys reported higher academic stress and better psychological wellbeing, and these have been attributed partly to the socialisation role of gender. These results have policy implications in respect of the creation of a cordial school environment as well as encouraging a healthy interpersonal relationship between adolescents and their family and friends with the aim of reducing academic stress appraisal which is inimical to the psychological wellbeing of adolescents.
Heterotrophic and Autotrophic Soil Respiration under Simulated Dormancy Conditions  [PDF]
Daniel Beverly, Scott Franklin
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.53024
Abstract: Carbon cycling research has increased over the past 20 years, but less is known about the primary contributors to soil respiration (i.e. heterotrophic and autotrophic) under dormant conditions. It is understood that soil CO2 effluxes are significantly lower during the winter of temperate ecosystems and assumed microorganisms dominate efflux origination. We hypothesized that heterotrophic contributions would be greater than autotrophic under simulated dormancy conditions. To test this hypothesis, we designed an experiment with the following treatments: combined autotrophic heterotrophic respiration, heterotrophic respiration, autotrophic respiration, no respiration, autotrophic respiration in vermiculite, and no respiration in vermiculite. Engelmann spruce seedlings and soil substrates were placed in specially designed respiration chambers and soil CO2 efflux measurements were taken four times over the course of a month. Soil microbial densities and root volumes were measured for each chamber after day thirty-three. Seedling presence resulted in significantly higher soil CO2 efflux rates for all soil substrates. Autotrophic respiration treatments were not representative of solely autotrophic soil CO2 efflux due to soil microbial contamination of autoclaved soil substrates; however, the mean autotrophic contributions averaged less than 25% of the total soil CO2 efflux. Soil microorganism communities were likely the primary contributor to soil CO2 efflux in simulated dormant conditions, as treatments with the greatest proportions of microbial densities had the highest soil CO2 efflux rates. Although this study is not directly comparable to field dormant season soil CO2 effluxes of Engelmann spruce forest, as snowpack is not maintained throughout this experiment, relationships, and metrics from such small-scale ecosystem component processes may yield more accurate carbon budget models.
Microcredit Schemes: A Tool for Promoting Rural Savings Capacity among Poor Farm Families: A Case Study in the Eastern Region of Ghana  [PDF]
Mercy Asamoah, Franklin Manu Amoah
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.31003
Abstract: Savings mobilization is crucial for any viable economic and investment activity. In rural agricul-ture, the ability to save or to mobilize capital in cash at bank or stock of wealth is a major prerequisite as the collateral for accessing bank loans. The ability to save among rural poor households is however, difficult due to their low income levels and inability to make personal savings commitment. According to Yunus (2000) [1], failure of traditional financial institutions to extend credit to the poor is the single most important reason for the perpetuation of poverty. Nevertheless, since the early 1980s, microfinance scheme has been identified as a useful tool that can effectively mobilise savings among poor households. Yunus (2003) [2] indicated that micro-credit schemes have developed unique characteristics in terms of unconventional approaches, organizational and lending procedures that have resulted in high rates of repayments, savings mobilization and the ability to nurture a culture of commitment and self-reliance of poor people. The objective of this study was to assess the role microfinance plays in savings mobilization among farm households, analyse the extent of savings mobilized by participants and evaluate the conditions for membership of such schemes. A total of 212 respondents in organised cocoa farmer Associations since 2010 in the Eastern region were interviewed using formal questionnaires. The results indicated that the microfinance model had helped the respondents, mainly small-scale cocoa farmers, to mobilize substantial savings in a convenient and tailor made way. The majority who did not have any savings culture before joining the schemes were surprised about their savings potential through the group concept. Also, the schemes allayed the fear of the participants to take credit from financial institutions with high (over 95%) repayment culture using peer support, group guarantee and social capital generated through the formation of associations. They also had easy access to farm inputs such as fertilizer to maintain their cocoa farms because of their savings mobilization. It is concluded that microfinance model is a potential tool that promotes savings culture which gives access to credit for small-scale cocoa farmers to purchase farm inputs to increase productivity and enhance their livelihood.
A Poisson Solver Based on Iterations on a Sylvester System  [PDF]
Michael B. Franklin, Ali Nadim
Applied Mathematics (AM) , 2018, DOI: 10.4236/am.2018.96052
Abstract:
We present an iterative scheme for solving Poisson’s equation in 2D. Using finite differences, we discretize the equation into a Sylvester system, AU +UB = F, involving tridiagonal matrices A and B. The iterations occur on this Sylvester system directly after introducing a deflation-type parameter that enables optimized convergence. Analytical bounds are obtained on the spectral radii of the iteration matrices. Our method is comparable to Successive Over-Relaxation (SOR) and amenable to compact programming via vector/array operations. It can also be implemented within a multigrid framework with considerable improvement in performance as shown herein.
Insulation for Daydreams: A Role for Tonic Norepinephrine in the Facilitation of Internally Guided Thought
Jonathan Smallwood, Kevin S. Brown, Benjamin Baird, Michael D. Mrazek, Michael S. Franklin, Jonathan W. Schooler
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033706
Abstract: Although consciousness can be brought to bear on both perceptual and internally generated information, little is known about how these different cognitive modes are coordinated. Here we show that between-participant variance in thoughts unrelated to the task being performed (known as task unrelated thought, TUT) is associated with longer response times (RT) when target presentation occurs during periods when baseline Pupil Diameter (PD) is increased. As behavioral interference due to high baseline PD can reflect increased tonic activity in the norepinephrine system (NE), these results might implicate high tonic NE activity in the facilitation of TUTs. Based on these findings, it is hypothesised that high tonic mode NE leads to a generalised de-amplification of task relevant information that prioritses internally generated thought and insulates it from the potentially disruptive events taking place in the external environment.
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