title: Refining the use of the web (and web search) as a language teaching and learning resource

authors: Wu, Shaoqun

subjects: computer science

abstract: The web is a potentially useful corpus for language study because it provides examples of language that are contextualized and authentic, and is large and easily searchable. However, web contents are heterogeneous in the extreme, uncontrolled and hence 'dirty,' and exhibit features different from the written and spoken texts in other linguistic corpora. This article explores the use of the web and web search as a resource for language teaching and learning. We describe how a particular derived corpus containing a trillion word tokens in the form of n-grams has been filtered by word lists and syntactic constraints and used to create three digital library collections, linked with other corpora and the live web, that exploit the affordances of web text and mitigate some of its constraints.

text: Refining the use of the web (and web search) as a language teaching and learning resource The web is a potentially useful corpus for language study because it provides examples of language that are contextualized and authentic, and is large and easily searchable. However, web contents are heterogeneous in the extreme, uncontrolled and hence 'dirty,' and exhibit features different from the written and spoken texts in other linguistic corpora. This article explores the use of the web and web search as a resource for language teaching and learning. We describe how a particular derived corpus containing a trillion word tokens in the form of n-grams has been filtered by word lists and syntactic constraints and used to create three digital library collections, linked with other corpora and the live web, that exploit the affordances of web text and mitigate some of its constraints.

year: 2009

title: A contrast-sensitive, redundancy reduction mechanism acting on MT neurons can explain global motion direction biases without the need for Bayesian priors

authors: Perrone, John A.

subjects: Bayesian observer model

abstract: Introduction: The perceived global direction of moving objects can be influenced by the contrast of the object (Weiss, Simoncelli & Adelson, Nature Neuroscience, 2002). There is currently no detailed, neural-based explanation for how this could occur. Weiss et al., proposed an ideal Bayesian observer model that included a physiologically unspecified ‘low speed’ prior. We have recently developed a new velocity code for extracting image velocity from small groups of MT neurons (Perrone & Krauzlis, VSS 2011). The code includes a stage of local spatial inhibition between MT neurons designed to reduce the amount of redundant signals passed onto the global motion integration stage (MST). The inhibition is made dependent upon the contrast of the stimulus by exploiting the fact that some MT neurons change their speed tuning (V shifts to ∼ .5V) at low contrast (Krekelberg et al., J. Neurosci., 2006). An inhibitory signal based on the difference in output from two such MT units tuned to V and 2V will be high at high contrast, but will switch off at low contrast when the input speed is V.
Methods: We tested our velocity code using high- and low-contrast rhombus stimuli that have been shown to produce contrast dependent biases in global motion estimates (Weiss, et al., 2002).
Results: The model produced contrast dependent estimates of global motion direction that match the perceptual results. Low contrast rhomboids tended to produce estimates orthogonal to the major axis of the rhombus whereas high contrast rhomboids produced estimates closer to the veridical direction. Our simulations indicate that at low contrast the spatial inhibitory mechanisms between MT neurons may be switching off causing an increase in the density of responses signalling motion orthogonal to the edges.
Conclusion: Our model provides a biologically plausible mechanism by which the Weiss et al., Bayesian prior could be implemented.

text: A contrast-sensitive, redundancy reduction mechanism acting on MT neurons can explain global motion direction biases without the need for Bayesian priors Introduction: The perceived global direction of moving objects can be influenced by the contrast of the object (Weiss, Simoncelli & Adelson, Nature Neuroscience, 2002). There is currently no detailed, neural-based explanation for how this could occur. Weiss et al., proposed an ideal Bayesian observer model that included a physiologically unspecified ‘low speed’ prior. We have recently developed a new velocity code for extracting image velocity from small groups of MT neurons (Perrone & Krauzlis, VSS 2011). The code includes a stage of local spatial inhibition between MT neurons designed to reduce the amount of redundant signals passed onto the global motion integration stage (MST). The inhibition is made dependent upon the contrast of the stimulus by exploiting the fact that some MT neurons change their speed tuning (V shifts to ∼ .5V) at low contrast (Krekelberg et al., J. Neurosci., 2006). An inhibitory signal based on the difference in output from two such MT units tuned to V and 2V will be high at high contrast, but will switch off at low contrast when the input speed is V.
Methods: We tested our velocity code using high- and low-contrast rhombus stimuli that have been shown to produce contrast dependent biases in global motion estimates (Weiss, et al., 2002).
Results: The model produced contrast dependent estimates of global motion direction that match the perceptual results. Low contrast rhomboids tended to produce estimates orthogonal to the major axis of the rhombus whereas high contrast rhomboids produced estimates closer to the veridical direction. Our simulations indicate that at low contrast the spatial inhibitory mechanisms between MT neurons may be switching off causing an increase in the density of responses signalling motion orthogonal to the edges.
Conclusion: Our model provides a biologically plausible mechanism by which the Weiss et al., Bayesian prior could be implemented.

year: 2012

title: Recognising the negative impacts of aquatic weed management: Okawa Bay, Lake Rotoiti case study

authors: Scholes, Paul

abstract: The Te Arawa Rotorua Lakes Programme continues to implement measures to maintain and restore lake water quality in line with trophic level indices (TLI’s) for respective lakes. In Lakes Rotorua and Rotoiti this has also meant not only reducing nutrients to and in the lakes but also managing periodic cyano-bacterial (blue-green) algal blooms.
Restoration measures in the Rotorua and Rotoiti catchments have included land use management efforts to arrest nutrient inputs; diversion of Lake Rotorua waters from entering Rotoiti; sewage reticulation of lakeside communities; and treatment of inflows
with aluminium sulphate (alum). While restoration efforts have produced water quality gains in both lakes, in recent years, cyano-bacterial blooms have occurred in the shallow embayment of Lake Rotoiti, known as Okawa Bay.
These water quality gains have not come without a cost. Submerged aquatic weeds such as Hornwort are an increasing problem in the Rotorua Te Arawa Lakes and significant resources are needed to manage infestations primarily for aesthetic and recreational
amenity. Control of exotic aquatic weed is mostly with application of herbicide. Herbicide treatment leaves a decomposing biomass in the waterbody, potentially increasing the nutrient status.
We examine the impact aquatic weed decomposition has had on Okawa Bay’s nutrient status and the cyano-bacterial blooms over recent summers, and Bay of Plenty Regional Council’s response to reduce localised bloom development.

text: Recognising the negative impacts of aquatic weed management: Okawa Bay, Lake Rotoiti case study The Te Arawa Rotorua Lakes Programme continues to implement measures to maintain and restore lake water quality in line with trophic level indices (TLI’s) for respective lakes. In Lakes Rotorua and Rotoiti this has also meant not only reducing nutrients to and in the lakes but also managing periodic cyano-bacterial (blue-green) algal blooms.
Restoration measures in the Rotorua and Rotoiti catchments have included land use management efforts to arrest nutrient inputs; diversion of Lake Rotorua waters from entering Rotoiti; sewage reticulation of lakeside communities; and treatment of inflows
with aluminium sulphate (alum). While restoration efforts have produced water quality gains in both lakes, in recent years, cyano-bacterial blooms have occurred in the shallow embayment of Lake Rotoiti, known as Okawa Bay.
These water quality gains have not come without a cost. Submerged aquatic weeds such as Hornwort are an increasing problem in the Rotorua Te Arawa Lakes and significant resources are needed to manage infestations primarily for aesthetic and recreational
amenity. Control of exotic aquatic weed is mostly with application of herbicide. Herbicide treatment leaves a decomposing biomass in the waterbody, potentially increasing the nutrient status.
We examine the impact aquatic weed decomposition has had on Okawa Bay’s nutrient status and the cyano-bacterial blooms over recent summers, and Bay of Plenty Regional Council’s response to reduce localised bloom development.

year: 2015