2,096 research outputs found
Lack of lecturer clarity during instruction: Possible reason for poor throughput?
In South Africa, students’ academic success in tertiary environments  is generally low, despite governmental or institutional interventions. This article, underpinned by the General Model of Instructional Communication by McCroskey, Valencic and Richmond (2004), explores participant lecturers’ perceptions of lecturer clarity during instruction, and their students’. A mixed methods case study was conducted, with a convenience sample of seven lecturers, interviewed and observed in situ. Questionnaires were completed by 252 first year students at a South African university of technology. Content and statistical analysis of the data revealed that a mismatch existed between lecturers’ perceptions of their own instructional clarity and their students’. The high percentage of students who felt lost during a lecture suggests a high level of instructional dissonance (Evans, 2005) which might account for a less-than desirable academic throughput. We recommend that institutions quality assure lecturers’ oral, written, content and process clarity prior to and during appointment.
Herbicide Control of Tall Larkspurs on Mountain Rangeland
Tall larkspurs kill more cattle on mountain rangelands than any other plant or disease. Tall larkspurs are principal components of tall forb communities and occur in patches associated with snow drifts in mountain big sagebrush, aspen and subalpine plant communities. Controlling larkspur patches can substantially reduce cattle deaths (3). Larkspur will never be eradicated, but if its density could be reduced to where a cow could not eat enough larkspur, fast enough, death losses can be reduced
Sensory augmentation with distal touch: The tactile helmet project
The Tactile Helmet is designed to augment a wearer's senses with a long range sense of touch. Tactile specialist animals such as rats and mice are capable of rapidly acquiring detailed information about their environment from their whiskers by using task-sensitive strategies. Providing similar information about the nearby environment, in tactile form, to a human operator could prove invaluable for search and rescue operations, or for partially-sighted people. Two key aspects of the Tactile Helmet are sensory augmentation, and active sensing. A haptic display is used to provide the user with ultrasonic range information. This can be interpreted in addition to, rather than instead of, visual or auditory information. Active sensing systems "are purposive and information-seeking sensory systems, involving task specific control of the sensory apparatus" [1]. The integration of an accelerometer allows the device to actively gate the delivery of sensory information to the user, depending on their movement. Here we describe the hardware, sensory transduction and characterisation of the Tactile Helmet device, before outlining potential use cases and benefits of the system. © 2013 Springer-Verlag Berlin Heidelberg
Whiskered texture classification with uncertain contact pose geometry
Tactile sensing can be an important source of information for robots, and texture discrimination in particular is useful in object recognition and terrain identification. Whisker based tactile sensing has recently been shown to be a promising approach for mobile robots, using simple sensors and many classification approaches. However these approaches have often been tested in limited environments, and have not been compared against one another in a controlled way. A wide range of whisker-object contact poses are possible on a mobile robot, and the effect such contact variability has on sensing has not been properly investigated. We present a novel, carefully controlled study of simple surface texture classifiers on a large set of varied pose conditions that mimic those encountered by mobile robots. Namely, single brief whisker contacts with textured surfaces at a range of surface orientations and contact speeds. Results show that different classifiers are appropriate for different settings, with spectral template and feature based approaches performing best in surface texture, and contact speed estimation, respectively. The results may be used to inform selection of classifiers in tasks such as tactile SLAM
CrunchBot : a mobile whiskered robot platform
CrunchBot is a robot platform for developing models of tactile perception and navigation. We present the architecture of CrunchBot, and show why tactile navigation is difficult. We give novel real-time performance results from components of a tactile navigation system and a description of how they may be integrated at a systems level. Components include floor surface classification, radial distance estimation and navigation. We show how tactile-only navigation differs fundamentally from navigation tasks using vision or laser sensors, in that the assumptions about the data preclude standard algorithms (such as extended Kalman Filters) and require brute-force methods
First order phase transition with a logarithmic singularity in a model with absorbing states
Recently, Lipowski [cond-mat/0002378] investigated a stochastic lattice model
which exhibits a discontinuous transition from an active phase into infinitely
many absorbing states. Since the transition is accompanied by an apparent
power-law singularity, it was conjectured that the model may combine features
of first- and second-order phase transitions. In the present work it is shown
that this singularity emerges as an artifact of the definition of the model in
terms of products. Instead of a power law, we find a logarithmic singularity at
the transition. Moreover, we generalize the model in such a way that the
second-order phase transition becomes accessible. As expected, this transition
belongs to the universality class of directed percolation.Comment: revtex, 4 pages, 5 eps figure
Aged carbon mineralisation from headwater peatland floodplains in the Peak District, UK
Floodplains are dynamic ecosystems that cycle carbon, which is both delivered from upstream catchment sources and produced in-situ. These systems are being increasingly recognised as key environments of carbon processing, with the capacity for substantial carbon storage, in addition to acting as hotspots of carbon mineralisation. The balance of storage versus mineralisation is dependent on a number of controls including landscape position and environmental conditions. This study focuses on three headwater floodplains downstream of a highly eroded blanket bog peatland in the Peak District, UK. Previous research has shown that aged organic carbon from peatland sources, has been stored in floodplains in this area, and therefore, we aimed to understand whether allochthonous carbon was being mineralised in this context. We examined sediment cores and analysed the radiocarbon (14C) content of soil-respired CO2, using a partitioning approach to scrutinise the depth and age relations of respiration in the individual floodplains, and patterns of age distributions downstream. Aged organic carbon was released from the upper and mid floodplain sites (14C ages of 682 and 232 years BP, respectively), whereas only modern dates were recorded at the lower site. The geomorphic context and sedimentology supported these results, with the stratigraphy suggesting a dominance of allochthonous deposition at the upper sites, but primarily in-situ soil development at the lower site. There were no trends of radiocarbon age with depth in the individual floodplains, suggesting that floodplain sediments were well mixed and that aged organic matter was being processed both at the surface and at depth in the uppermost sites. An isotope mass balance mixing model indicated the dominance of two sources of CO2; recently fixed C3 organic matter (<10 years old) and CO2 produced by methanogenesis. The results indicate that floodplains in a relatively narrow halo around eroding headwater peatlands, could be important sites of aged carbon turnover originally derived from upstream sources. Reworked carbon does not transfer passively through the system and experiences periods of deposition where it can be subject to microbial action. This is an important consideration in other environments where organic carbon has previously been ‘locked up’ (e.g., permafrost regions) but is now under the threat of release due to climate change
The interpretive approach to religious education : challenging Thompson's interpretation
In a recent book chapter, Matthew Thompson makes some criticisms of my work, including the interpretive approach to religious education and the research and activity of Warwick Religions and Education Research Unit. Against the background of a discussion of religious education in the public sphere, my response challenges Thompson’s account, commenting on his own position in relation to dialogical approaches to religious education. The article rehearses my long held view that the ideal form of religious education in fully state funded schools of a liberal democracy should be ‘secular’ but not ‘secularist’; there should be no implication of an axiomatic secular humanist interpretation of religions
Boron Fullerenes: A First-Principles Study
A family of unusually stable boron cages was identified and examined using
first-principles local density functional method. The structure of the
fullerenes is similar to that of the B12 icosahedron and consists of six
crossing double-rings. The energetically most stable fullerene is made up of
180 boron atoms. A connection between the fullerene family and its precursors,
boron sheets, is made. We show that the most stable boron sheets are not
necessarily precursors of very stable boron cages. Our finding is a step
forward in the understanding of the structure of the recently produced boron
nanotubes.Comment: 10 pages, 4 figures, 1 tabl
Equilibrium Properties of A Monomer-Monomer Catalytic Reaction on A One-Dimensional Chain
We study the equilibrium properties of a lattice-gas model of an catalytic reaction on a one-dimensional chain in contact with a reservoir
for the particles. The particles of species and are in thermal contact
with their vapor phases acting as reservoirs, i.e., they may adsorb onto empty
lattice sites and may desorb from the lattice. If adsorbed and
particles appear at neighboring lattice sites they instantaneously react and
both desorb. For this model of a catalytic reaction in the
adsorption-controlled limit, we derive analytically the expression of the
pressure and present exact results for the mean densities of particles and for
the compressibilities of the adsorbate as function of the chemical potentials
of the two species.Comment: 19 pages, 5 figures, submitted to Phys. Rev.
- …