Attention gates visual coding in the human pulvinar.

The pulvinar nucleus of the thalamus is suspected to have an important role in visual attention, based on its widespread connectivity with the visual cortex and the fronto-parietal attention network. However, at present, there remain many hypotheses on the pulvinars specific function, with sparse or conflicting evidence for each. Here we characterize how the human pulvinar encodes attended and ignored objects when they appear simultaneously and compete for attentional resources. Using multivoxel pattern analyses on data from two functional magnetic resonance imaging (fMRI) experiments, we show that attention gates both position and orientation information in the pulvinar: attended objects are encoded with high precision, while there is no measurable encoding of ignored objects. These data support a role of the pulvinar in distractor filtering--suppressing information from competing stimuli to isolate behaviourally relevant objects

Bridging the Disconnect

New York City is facing a youth unemployment crisis, but the city's youth workforce development programs reach only a fraction of those in need of help and are too often misaligned to the developmental needs of young New Yorkers

Evaluating the Efficacy and Acceptability of Videoconferencing in School-Based Behavioral Consultation

School-based behavioral consultation is a way of providing psychological services to students through their teachers. This indirect service delivery model has been shown to be effective for improving academic and behavioral concerns. Typically, school-based behavioral consultation is conducted face-to-face (in-vivo) between consultants (psychologists) and consultee’s (teachers); however, current technologies have provided an alternative medium to communicate, via videoconferencing. Videoconferencing has been shown to be an effective alternative to face-to-face communication across many different practice domains and applications. Videoconferencing in schools, particularly for school-based behavioral consultation, may be a viable alternative. The proposed study evaluated the efficacy and acceptability of videoconferencing with teachers as an alternative means of conducting the problem identification interview of school-based behavioral consultation. A school psychology doctoral student interviewed teachers on two occasions (face-to-face and via videoconferencing) to obtain information about student problem behavior. The videoconferencing interviews were conducted across iPads using the videoconferencing software FaceTime. All interviews were video recorded and transcribed into text to code verbalizations, using the Consultation Analysis Record (CAR). Frequencies of verbalizations were totaled on the Consultation Analysis checklist (CAC) into 14 required categories. Data from the CAC was used to evaluate the efficacy of the interviews. Additionally, teachers completed two brief measures, the Fast Form of the Technology Acceptability Model (FF-TAM) and the Distance Communication Comfort Scale (DCCS) pre and post interviews. Data from The FF-TAM and DCCS was used to evaluate the acceptability of videoconferencing. Finally, moderators of the acceptability of videoconferencing were evaluated using a multiple regression analysis

Remedies for anticipatory breach of contract

Includes bibliographical referencesThe thesis discusses the origin and development of anticipatory breach of contract in South African law leading up to the decision in Datacolor International (Pty) Ltd v Intamarket (Pty) Ltd 2001 (2) SA 284 (SCA) and the implications of this decision on the law. This decision is generally regarded as the culmination of the development of a 'new approach' to repudiation, as a form of anticipatory breach of contract, in South African law and this 'new approach' and other aspects of the decision will be discussed in detail. Drawing on Datacolor International (Pty) Ltd v Intamarket (Pty) Ltd and the decisions of Lord Diplock in English law the thesis proposes a model for anticipatory breach of contract that defines anticipatory breach of contract as conduct or circumstances that support a conclusion, with reasonable certainty, that a contracting party will fail to perform their primary obligations under the contract correctly and that such failure justifies affording the aggrieved party a right to cancel the contract. Anticipatory breach of contract will therefore always amount to a material breach of contract, where material breach of contract consists of a failure by a contracting party to perform her or his primary obligations correctly, or conduct which indicates with reasonable certainty that she or he will fail to perform their primary obligations correctly, which will substantially deprive the aggrieved party of the benefit of the contract. If, balancing the interests of the parties, it would be fair to afford the aggrieved party a right to cancel the contract this conduct will amount to a material breach of contract. Anticipatory breaches of contract are those material breaches which consist of conduct indicating that a failure will occur rather than consisting of the actual failure to perform a primary obligation. In addition to defining when the remedy of cancellation is available to an aggrieved party the thesis also proposes certain other modifications to the remedies available to an aggrieved party facing an anticipatory breach of contract including introducing into the South African law, as a remedy for an anticipated breach of contract, a 'request for an adequate assurance of performance' modelled on the remedy of the same name originating in the Uniform Commercial Code

Evaluating the differential effects of parental involvement on check in/check out in children with externalizing behavior problems

School-based interventions are typically implemented based on a Response to Intervention model, i.e., a 3-tiered support system. Tier 1 provides universal support for all students; Tier 2 targets children who are at risk for developing problems; Tier 3 focuses on remediation for children with severe problems. The interventions in Tier 2 are important because they provide an opportunity to access children before their problems become critically dysfunctional. Check in/Check out (CICO) is a Tier 2 intervention that has been evaluated for children with externalizing behavior problems. In the current CICO literature, parent involvement during CICO integrates school and home life, but the specific effects of parent involvement have not been evaluated with adequate treatment integrity. The current study evaluated the differential effects of parent involvement on CICO. The Brief Behavior Rating Scale, a 12-item change sensitive problem behavior scale, was the dependent measure used to evaluate parent involvement. The effect of parent involvement was evaluated using a reversal design (A-B-A-C). The current study hypothesized that children would show lower levels of problem behavior when parent-based reinforcement was implemented, rather then mentor-based reinforcement, in CICO. Results showed that students responded to the CICO intervention, however it was only effective for certain participants. Mentor-provided reinforcement CICO was more effective than parent-provided reinforcement CICO, and there was a strong correlation between the Brief Behavior Rating (BBR) and the Daily Progress Report (DPR). Results are discussed and the studies limitations were considered

Attention Narrows Position Tuning of Population Responses in V1

SummaryWhen attention is directed to a region of space, visual resolution at that location flexibly adapts, becoming sharper to resolve fine-scale details or coarser to reflect large-scale texture and surface properties [1]. By what mechanism does attention improve spatial resolution? An improved signal-to-noise ratio (SNR) at the attended location contributes [2], because of retinotopically specific signal gain [3–10]. Additionally, attention could sharpen position tuning at the neural population level, so that adjacent objects activate more distinct regions of the visual cortex. A dual mechanism involving both signal gain and sharpened position tuning would be highly efficient at improving visual resolution, but there is no direct evidence that attention can narrow the position tuning of population responses. Here, we compared the spatial spread of the fMRI BOLD response for attended versus ignored stimuli. The activity produced by adjacent stimuli overlapped less when subjects were attending at their locations versus attending elsewhere, despite a stronger peak response with attention. Our results show that even as early as primary visual cortex (V1), spatially directed attention narrows the tuning of population-coded position representations

Molecular dynamics in arbitrary geometries : parallel evaluation of pair forces

A new algorithm for calculating intermolecular pair forces in molecular dynamics (MD) simulations on a distributed parallel computer is presented. The arbitrary interacting cells algorithm (AICA) is designed to operate on geometrical domains defined by an unstructured, arbitrary polyhedral mesh that has been spatially decomposed into irregular portions for parallelisation. It is intended for nano scale fluid mechanics simulation by MD in complex geometries, and to provide the MD component of a hybrid MD/continuum simulation. The spatial relationship of the cells of the mesh is calculated at the start of the simulation and only the molecules contained in cells that have part of their surface closer than the cut-off radius of the intermolecular pair potential are required to interact. AICA has been implemented in the open source C++ code OpenFOAM, and its accuracy has been indirectly verified against a published MD code. The same system simulated in serial and in parallel on 12 and 32 processors gives the same results. Performance tests show that there is an optimal number of cells in a mesh for maximum speed of calculating intermolecular forces, and that having a large number of empty cells in the mesh does not add a significant computational overhead

Retired A Stars: The Effect of Stellar Evolution on the Mass Estimates of Subgiants

Doppler surveys have shown that the occurrence rate of Jupiter-mass planets appears to increase as a function of stellar mass. However, this result depends on the ability to accurately measure the masses of evolved stars. Recently, Lloyd (2011) called into question the masses of subgiant stars targeted by Doppler surveys. Lloyd argues that very few observable subgiants have masses greater than 1.5 Msun, and that most of them have masses in the range 1.0-1.2 Msun. To investigate this claim, we use Galactic stellar population models to generate an all-sky distribution of stars. We incorporate the effects that make massive subgiants less numerous, such as the initial mass function and differences in stellar evolution timescales. We find that these effects lead to negligibly small systematic errors in stellar mass estimates, in contrast to the roughly 50% errors predicted by Lloyd. Additionally, our simulated target sample does in fact include a significant fraction of stars with masses greater than 1.5 Msun, primarily because the inclusion of an apparent magnitude limit results in a Malmquist-like bias toward more massive stars, in contrast to the volume-limited simulations of Lloyd. The magnitude limit shifts the mean of our simulated distribution toward higher masses and results in a relatively smaller number of evolved stars with masses in the range 1.0-1.2 Msun. We conclude that, within the context of our present-day understanding of stellar structure and evolution, many of the subgiants observed in Doppler surveys are indeed as massive as main-sequence A stars.Comment: Accepted to ApJ, 5 pages, 3 figures; changed title, reworded introduction and conclusion

The hierarchical sparse selection model of visual crowding

Because the environment is cluttered, objects rarely appear in isolation. The visual system must therefore attentionally select behaviorally relevant objects from among many irrelevant ones. A limit on our ability to select individual objects is revealed by the phenomenon of visual crowding: an object seen in the periphery, easily recognized in isolation, can become impossible to identify when surrounded by other, similar objects. The neural basis of crowding is hotly debated: while prevailing theories hold that crowded information is irrecoverable – destroyed due to over-integration in early stage visual processing – recent evidence demonstrates otherwise. Crowding can occur between high-level, configural object representations, and crowded objects can contribute with high precision to judgments about the “gist” of a group of objects, even when they are individually unrecognizable. While existing models can account for the basic diagnostic criteria of crowding (e.g., specific critical spacing, spatial anisotropies, and temporal tuning), no present model explains how crowding can operate simultaneously at multiple levels in the visual processing hierarchy, including at the level of whole objects. Here, we present a new model of visual crowding—the hierarchical sparse selection (HSS) model, which accounts for object-level crowding, as well as a number of puzzling findings in the recent literature. Counter to existing theories, we posit that crowding occurs not due to degraded visual representations in the brain, but due to impoverished sampling of visual representations for the sake of perception. The HSS model unifies findings from a disparate array of visual crowding studies and makes testable predictions about how information in crowded scenes can be accessed