Comparison of the short- and long-lasting effects of perforant path kindling on radial maze learning.

Compared the long-lasting with the short-lasting effects of kindling the perforant path input to the hippocampal formation on the acquisition of 2 radial maze tasks. Animals in the long-term group were fully kindled (i.e., Stage 5 motor seizures were evoked) prior to a stimulation-free training period. Animals in the short-term group were kindled 30–45 min prior to each learning trial. A 3rd group of animals served as controls and were never kindled. On both 8-arm and 4/8-arm radial maze tasks, learning impairments were apparent only in the short-term group. Thus, the impaired learning is more likely related to the short-term aftereffects of an afterdischarge than to any long-term alterations in the neuronal status of the brain caused by kindling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms for fracture and fatigue-crack propagation in a bulk metallic glass

The fracture and fatigue properties of a newly developed bulk metallic glass alloy, Zr_41.2Ti_13.8Cu_12.5 Ni₁₀Be_22.5 (at. pct), have been examined. Experimental measurements using conventional fatigue precracked compact-tension C(T) specimens (∼7-mm thick) indicated that the fully amorphous alloy has a plane-strain fracture toughness comparable to polycrystalline aluminum alloys. However, significant variability was observed and possible sources are identified. The fracture surfaces exhibited a vein morphology typical of metallic glasses, and, in some cases, evidence for local melting was observed. Attempts were made to rationalize the fracture toughness in terms of a previously developed micromechanical model based on the Taylor instability, as well as on the observation of extensive crack branching and deflection. Upon partial or complete crystallization, however, the alloy was severely embrittled, with toughnesses dropping to ∼1 MPa . Commensurate with this drop in toughness was a marginal increase in hardness and a reduction in ductility (as measured via depthsensing indentation experiments). Under cyclic loading, crack-propagation behavior in the amorphous structure was similar to that observed in polycrystalline steel and aluminum alloys. Moreover, the crack-advance mechanism was associated with alternating blunting and resharpening of the crack tip. This was evidenced by striations on fatigue fracture surfaces. Conversely, the (unnotched) stress/life (S/N) properties were markedly different. Crack initiation and subsequent growth occurred quite readily, due to the lack of microstructural barriers that would normally provide local crack-arrest points. This resulted in a low fatigue limit of ∼4 pct of ultimate tensile strength.     

Effects of in utero methylmercury exposure on a spatial delayed alternation task in monkeys

Mycoplasma gallisepticum and M synoviae are important avian pathogens causing respiratory diseases which result in great economic losses in poultry farming. Two oligonucleotide probes, complementary to the variable region V8 of 16S rRNA from the avian mycoplasmas M gallisepticum and M synoviae have, therefore, been designed and used in direct filter hybridisation experiments. Both probes gave strong hybridisation signals with their homologous targets, whereas no cross-hybridisations were obtained with any of the other avian mycoplasmas tested. It was possible to detect 2-3 x 10(4) mycoplasma organisms by direct filter hybridisation experiments with radiolabelled probes. The probes were also used to analyse several laboratory strains and field isolates of M gallisepticum and M synoviae with complete agreement between the probe technique and the other methods used for species determination. Atypical M gallisepticum strains also gave strong hybridisation signals with the M gallisepticum specific probe.     

Maintenance of quality of life improvements in diverse rural older adults.

The maintenance of effects from home-delivered cognitive-behavioral therapy (CBT) was examined. One hundred thirty-four participants, predominantly African American and primarily rural, low-resource, and physically frail, were randomly assigned to either immediate or delayed CBT. The six-month follow-up assessments indicated that among those who remained in the study, participants evidenced significantly improved quality of life and reductions in psychological symptoms at follow-up, relative to pretreatment levels. Posttreatment gains were maintained at follow-up. These data suggest that treatment effects can be achieved and perhaps maintained with a disadvantaged sample of older adults and suggest that evidence-based treatments delivered through nontraditional means can have effects beyond posttreatment. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On the benign qualities of behavioral disinhibition: Because of the prosocial nature of people, behavioral disinhibition can weaken pleasure with getting more than you deserve.

This article focuses on social situations in which people are surprised about what is happening and inhibited about how to respond to the situation at hand. We study these situations by examining a classic topic in social psychology: how people respond to receiving better outcomes than are deserved. In these situations, the actions of an authority or a coworker push in the direction of accepting and enjoying the unfair outcome, whereas personal values for most people push in the direction of rejecting or being displeased with the outcome. This conflict may inhibit people's response to the advantageous but unfair outcomes. If people are indeed inhibited about how to respond to these kinds of outcomes, then lowering behavioral inhibition by reminding people of having acted in the past without inhibitions (in a manner that is unrelated to the outcomes participants subsequently receive) should affect reactions to the outcomes. Specifically, we hypothesize that because many people are prosocial and want to adhere to principles of fairness, reminders of behavioral disinhibition will lead to less pleasure with the unfairly obtained outcomes. The results of 8 experiments (conducted both inside and outside the psychology laboratory) revealed evidence for this benign disinhibition effect on various reactions to outcomes that are better than deserved. In further accordance with our line of reasoning, the effect is particularly pronounced among those who adhere to a prosocial orientation or who have adopted a prosocial mindset and is not observed among those with proself orientations or mindsets. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

An Inquiry-led Personalised Navigation System (IPNS) using multi-dimensional linkbases

The simplicity of the hypertext model behind the World Wide Web is a factor in its success, but this simplicity brings limitations. One of these limitations is embedding links in documents. Open Hypermedia addresses this by instead storing them in separate link databases. Meanwhile, the Adaptive Hypermedia approach seeks to enhance a user's experience by inserting personalised additional content and links on the web page. However, these techniques do not offer the user any control over the adaptation. In this paper, we propose the concept of a multi-dimensional linkbase for adaptive links presentation. Links are created and stored in a single, multi-dimensional, linkbase that provides presentation links based on the user's preferences and profile. We present a web-based system Inquiry-led Personalised Navigation System that implements this multi-dimensional concept for controlling its personalisation of hyperlinks. We give the results of our evaluation, which confirm that user-controlled adaptation is a satisfactory approach to providing users with control over personalisation, and can alleviate the link overload problem.     

Effects of integrated instruction on motivation and strategy use in reading.

Effects of instructional context on intrinsic and extrinsic motivation have been examined with a variety of studies. This quasi experiment compared students receiving an instructional intervention designed to increase intrinsic motivation with students receiving traditional instruction. Concept-oriented reading instruction (CORI) integrated reading and language arts with science inquiry. It emphasized learning goals, real-world interaction (hands-on science activities), competence support (strategy instruction), autonomy support (self-directed learning), and collaboration. Traditional classrooms had the same content objectives and comparable teachers but different pedagogy. Children in CORI classrooms scored higher on motivation than did children in traditional classrooms, with effect sizes of 1.94 for curiosity and 1.71 for strategy use. Grade-level differences were found for recognition and competition. The results show that classroom contexts can be constructed to influence motivational outcomes positively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Traffic fatalities, Peltzman's model, and directed graphs

We show how statistical methods based on directed graphs may be useful in modeling traffic fatalities by comparing models specified using directed graphs to a model originally developed by Peltzman. The comparison uses Peltzman's original data, as well as up-dated data (and coefficients) through 1993. Out-of-sample forecasts of traffic fatalities from Peltzman's model are compared with those from a model constructed using directed graphs over data for the more recent period. The directed graphs model outperforms Peltzman's model in root mean squared forecast error.     

Topology optimization of large scale stokes flow problems

This note considers topology optimization of large scale 2D and 3D Stokes flow problems using parallel computations. We solve problems with up to 1,125,000 elements in 2D and 128,000 elements in 3D on a shared memory computer consisting of Sun UltraSparc IV CPUs.     

A Self-selection Technique for Flooding and Routing in Wireless Ad-hoc Networks

There is a fundamental difference between wireless and wired networks, since the latter employ point-to-point communication while the former use broadcast transmission as the communication primitive. In this paper, we describe an algorithm, called self-selection, which takes advantage of broadcast communication to efficiently implement the basic operation of selecting a node possessing some desired properties among all the neighbors of the requestor. Self-selection employs a prioritized transmission back-off delay scheme in which each node’s delay of transmitting a signal is dependent on the probability of the node’s ability to best perform a pertinent task, and in turn, enables the node to autonomously select itself for the task. We demonstrate the benefits of self-selection in two basic wireless ad hoc network communication algorithms: flooding and routing. By relating back-off delay to the signal strength of a received packet, we design an efficient variant of conventional flooding called Signal Strength Aware Flooding. By using distance-to-destination to derive back-off delay, we design a novel and fault-tolerant wireless ad hoc network routing protocol named Self-Selective Routing.