Connection and coordination: the interplay between architecture and dynamics in evolved model pattern generators

We undertake a systematic study of the role of neural architecture in shaping the dynamics of evolved model pattern generators for a walking task. First, we consider the minimum number of connections necessary to achieve high performance on this task. Next, we identify architectural motifs associated with high fitness. We then examine how high-fitness architectures differ in their ability to evolve. Finally, we demonstrate the existence of distinct parameter subgroups in some architectures and show that these subgroups are characterized by differences in neuron excitabilities and connection signs.     

Making working memory work: a computational model of learning in the prefrontal cortex and basal ganglia

The prefrontal cortex has long been thought to subserve both working memory (the holding of information online for processing) and executive functions (deciding how to manipulate working memory and perform processing). Although many computational models of working memory have been developed, the mechanistic basis of executive function remains elusive, often amounting to a homunculus. This article presents an attempt to deconstruct this homunculus through powerful learning mechanisms that allow a computational model of the prefrontal cortex to control both itself and other brain areas in a strategic, task-appropriate manner. These learning mechanisms are based on subcortical structures in the midbrain, basal ganglia, and amygdala, which together form an actor-critic architecture. The critic system learns which prefrontal representations are task relevant and trains the actor, which in turn provides a dynamic gating mechanism for controlling working memory updating. Computationally, the learning mechanism is designed to simultaneously solve the temporal and structural credit assignment problems. The model's performance compares favorably with standard backpropagation-based temporal learning mechanisms on the challenging 1-2-AX working memory task and other benchmark working memory tasks.     

Synthetic pyrethroid insecticides as replacements for chlorinated hydrocarbons for the control of wood-boring insects

The need for effective contact insecticides to replace γ-HCH and dieldrin is discussed. Four synthetic pyrethroids, permethrin, cypermethrin, decamethrin and fenvalerate were evaluated for control of the house longhorn beetle,Hylotrupes bajulus and the common furniture beetleAnobium punctatum. Permethrin was also tested againssLyctus brunneus and the termiteReticulitermes santonensis. Initial toxic effectiveness of all 4 pyrethroids was similar to or in the case of decamethrin, markedly better than γ-HCH and with the exception of fenvalerate their persistence in wood was superior to γ-HCH. They offer hopeful potential replacements for chlorinated hydrocarbons but further evaluation is necessary.     

A new device for performing reference point indentation without a reference probe

Here we describe a novel, hand-held reference point indentation (RPI), instrument that is designed for clinical measurements of bone material properties in living patients. This instrument differs from previous RPI instruments in that it requires neither a reference probe nor removal of the periosteum that covers the bone, thus significantly simplifying its use in patient testing. After describing the instrument, we discuss five guidelines for optimal and reproducible results. These are: (1) the angle between the normal to the surface and the axis of the instrument should be less than 10°, (2) the compression of the main spring to trigger the device must be performed slowly (>1 s), (3) the probe tip should be sharper than 10 μm; however, a normalized parameter with a calibration phantom can correct for dull tips up to a 100 μm radius, (4) the ambient room temperature should be between 4?°C and 37 °C, and (5) the effective mass of the bone or material under test must exceed 1 kg, or if under 1 kg, the specimen should be securely anchored in a fixation device with sufficient mass (which is not a requirement of previous RPI instruments). Our experience is that a person can be trained with these guidelines in about 5 min and thereafter obtain accurate and reproducible results. The portability, ease of use, and minimal training make this instrument suitable to measure bone material properties in a clinical setting.     

Internet pornography exposure and risky sexual behavior among adult males in the United States

Sexually transmitted infections (STIs) continue to pose a threat to the public health in the United States. Many sexual behaviors increase an individual’s risk of STI contraction. Chief among these are having unprotected sex, having sex with multiple partners, and either paying for sex or having sex for pay. The present study used General Social Survey (GSS) data from 2000, 2002, and 2004 to explore the association between exposure to internet pornography and these STI risk behaviors among adult US males. After controlling for demographic and individual difference covariates, internet pornography consumption was positively associated with having sex with multiple partners, engaging in paid sex, and having had extramarital sex. Internet pornography consumption was unrelated to having unprotected sex. Subsequent GSSs have not asked participants about exposure to internet pornography. As the GSS is the only ongoing, full-probability, national survey assessing social beliefs and behaviors, the present report provides unique insight into the risky sexual behavior patterns of adult male internet pornography consumers in the United States.     

A Continuous Local Motion Planning Framework for Unmanned Vehicles in Complex Environments

As the complexity of an unmanned vehicle’s operational environment increases so does the need to consider the obstacle space continually, and this is aided by splitting the motion planning functionality into distinct global and local layers. This paper presents a new continuous local motion planning framework, where the output and control space elements of the traditional receding horizon control problem are separated into distinct layers. This separation reduces the complexity of the local motion trajectory optimisation, enabling faster design and increased horizon length. The focus of this paper is on the output space component of this framework. Bezier polynomial functions are used to describe local motion trajectories which are constrained to vehicle performance limits and optimised to track a global trajectory. Development and testing is in simulation, targeted at a nonlinear model of a quadrotor unmanned air vehicle. The defined framework is used to provide situation-aware tracking of a global trajectory in the presence of static and dynamic obstacles, as well as realistic turbulence and gusts. Also demonstrated is the immediate-term decentralised deconfliction of multiple unmanned vehicles, and multiple formations of unmanned vehicles.     

Exploring the impact of software requirements on system-wide goals: a method using satisfaction arguments and i* goal modelling

This paper describes the application of requirements engineering concepts to support the analysis of the impact of new software systems on system-wide goals. Requirements on a new or revised software component of a socio-technical system not only have implications on the goals of the subsystem itself, but they also impact upon the goals of the existing integrated system. In industries such as air traffic management and healthcare, impacts need to be identified and demonstrated in order to assess concerns such as risk, safety, and accuracy. A method called PiLGRIM was developed which integrates means-end relationships within goal modelling with knowledge associated with the application domain. The relationship between domain knowledge and requirements, as described in a satisfaction argument, adds traceability rationale to help determine the impacts of new requirements across a network of heterogeneous actors. We report procedures that human analysts follow to use the concepts of satisfaction arguments in a software tool for i* goal modelling. Results were demonstrated using models and arguments developed in two case studies, each featuring a distinct socio-technical system??a new controlled airspace infringement detection tool for NATS (the UK??s air navigation service provider), and a new version of the UK??s HIV/AIDS patient reporting system. Results provided evidence towards our claims that the conceptual integration of i* and satisfaction arguments is usable and useful to human analysts, and that the PiLGRIM impact analysis procedures and tool support are effective and scalable to model and analyse large and complex socio-technical systems.     

Changes in the microbiological and shelf-life characteristics of beef tongues and livers following transcontinental and transoceanic shipment

The effects of transcontinental (interstate) transport and transoceanic shipment were determined on microbiological and shelf-life characteristics of beef tongues and livers. These variety meats were evaluated for both microbiological and shelf-life characteristics following slaughter in Guymon, Oklahoma, USA. The samples were then frozen and sent by refrigerated truck (4·5°C) to storage facilities in Jacksonville, Florida, USA. Further microbiological and shelf-life evaluations took place prior to overseas shipment at the University of Florida and following overseas shipment at The Institute CIVO-Technology, TNO, Zeist, The Netherlands. Aerobic plate counts (APCs) at 35°C for beef tongues showed a significant (P < 0·0.5) decrease following overseas shipment. Similar results were noted for beef livers. For both organs, the surface thawing in Florida, required for sampling, did not appear to affect the final bacterial counts. The 20°C APCs for beef tongues revealed a significant (P < 0·0.5) decrease following interstate transport but not transoceanic shipment. The 20°C APCs for beef livers did not differ significantly during the entire transportation period. The colour differences noted during transport of the product were probably the result of freezing and not of the actual shipping and storage conditions.     

Working memory capacity and the top-down control of visual search: Exploring the boundaries of "executive attention".

The executive attention theory of working memory capacity (WMC) proposes that measures of WMC broadly predict higher order cognitive abilities because they tap important and general attention capabilities (R. W. Engle & M. J. Kane, 2004). Previous research demonstrated WMC-related differences in attention tasks that required restraint of habitual responses or constraint of conscious focus. To further specify the executive attention construct, the present experiments sought boundary conditions of the WMC-attention relation. Three experiments correlated individual differences in WMC, as measured by complex span tasks, and executive control of visual search. In feature-absence search, conjunction search, and spatial configuration search, WMC was unrelated to search slopes, although they were large and reliably measured. Even in a search task designed to require the volitional movement of attention (J. M. Wolfe, G. A. Alvarez, & T. S. Horowitz, 2000), WMC was irrelevant to performance. Thus, WMC is not associated with all demanding or controlled attention processes, which poses problems for some general theories of WMC. (PsycINFO Database Record (c) 2010 APA, all rights reserved)