Programmed Shifts in Reward Quality and Quantity: A Planned Positive and Negative Contrast Analysis

Two experiments were conducted in an attempt to occasion both positive and negative contrast effects. The primary purpose was to occasion both decrements and increases in responding following planned shifts in quality or magnitude of reinforcement. Participants were children ages 7 to 16 years who were receiving therapy using Applied Behavior Analysis (ABA) and had a prior diagnosis of autism. In Experiment I, changes in responding were measured following manipulations of reinforcer quality. Results indicated response patterns consistent with negative contrast effects following shifts from high quality to low quality reinforcers, and positive contrast effects following shifts from low quality to high quality reinforcers. That is, responding in sessions following shifts from high to low magnitude reinforcers was lower than rates of responding in previous low quality conditions. Positive contrast was less consistently observed, but was seen as responding at higher rates during a second high-quality condition relative to the first following exposure to a low-quality condition. In Experiment II, responding was measured following shifts in reinforcer magnitude using a similar sequence of schedules as Experiment I. Both positive and negative contrast effects were observed, although less consistently than in Experiment I. Overall, the findings were consistent with the phenomena of positive and negative contrast effects in that one schedule of reinforcement produced changes in responding for a different schedule of reinforcement. Results were discussed in relation to the ideas of behavioral contrast and studies of intrinsic motivation

Teaching phoneme segmentation and blending: a comparison of two methods

Phonemic segmenting and blending is seen as one of the most critical skills necessary for the development of good reading skills in beginning readers. Research has shown that teaching phonemic skills results in improved reading for both trained (familiar) and untrained words when compared to teaching word-recognition reading strategies. Within the field of phonemic awareness teaching, results have been mixed as to the most effective methods of teaching phonemic skills, but it is generally agreed that explicit instruction in both segmenting and blending is better than instruction focusing on onset/rime or rhyming methods. The purpose of the current study is to compare two methods for explicitly teaching phonemic awareness. In the study, participants were taught to read nonsense words by either being presented with intact words and taught to segment and blend the individual phonemes making up the word, or by being presented with individual phonemes first, followed by the intact word through introduction of phonemes only, ending in the whole word. Hypothesized results are that teaching segmenting and blending in the context of the whole-word will result in better generalization to non-studied nonsense words than being taught blending in the context of initial presentation of separate phonemes before blending

An Ecological Assessment of Property and Violent Crime Rates Across a Latino Urban Landscape: The Role of Social Disorganization and Institutional Anomie Theory

The present research put forth an integrated theoretical framework aimed at providing a more holistic community- level approach explaining crime across a heavily populated Latino city. Guided by social disorganization and institutional anomie theory, this study used several data sources and OLS regression techniques to examine the impact of social disorganization, economic and noneconomic institutional characteristics on rates of property and violent crime across 1,016 census block groups in San Antonio, Texas. While several findings emerged, interactions between alcohol density and concentrated disadvantage were significant and positively associated with property and violent crime. Interactions between welfare generosity and concentrated disadvantage were significant and negatively associated with the outcomes

Oblique and curved D-branes in IIB plane-wave string theory

Oblique Dp-branes in the maximally supersymmetric type IIB plane-wave background are constructed in terms of boundary states, as well as from the open string point of view. These Dp-branes, whose existence was anticipated by Hikida and Yamaguchi from general supersymmetry arguments, have an isometry that is a subgroup of the diagonal SO(4) symmetry of the background. The oblique D3-brane is found to preserve four dynamical and four kinematical supersymmetries while the oblique D5-brane preserves one half of both the dynamical and kinematical supersymmetries. We also discuss the open-string boundary conditions for curved D7- and D5-branes, and analyze their supersymmetry.Comment: 27 page

Phase metrology with multi-cycle two-colour pulses

Strong-field phenomena driven by an intense infrared (IR) laser depend on during what part of the field cycle they are initiated. By changing the sub-cycle character of the laser electric field it is possible to control such phenomena. For long pulses, sub-cycle shaping of the field can be done by adding a relatively weak, second harmonic of the driving field to the pulse. Through constructive and destructive interference, the combination of strong and weak fields can be used to change the probability of a strong-field process being initiated at any given part of the cycle. In order to control sub-cycle phenomena with optimal accuracy, it is necessary to know the phase difference of the strong and the weak fields precisely. If the weaker field is an even harmonic of the driving field, electrons ionized by the field will be asymmetrically distributed between the positive and negative directions of the combined fields. Information about the asymmetry can yield information about the phase difference. A technique to measure asymmetry for few-cycle pulses, called Stereo-ATI (Above Threshold Ionization), has been developed by [Paulus G G, et al 2003 Phys. Rev. Lett. 91]. This paper outlines an extension of this method to measure the phase difference between a strong IR and its second harmonic

Constructing Crime: Neighborhood Characteristics and Police Recording Behavior

It has long been acknowledged that police officers have substantial levels of discretion in their day-to-day activities. There is a well developed body of literature that considers how this discretion is exercised across a broad array of situations including the decision to arrest, use force, and grant citizen requests for official action. Using both social disorganization and conflict theories as conceptual models, the purpose of this study was to determine if neighborhood characteristics affect police reporting behavior across a wide cross-section of reported call types. The findings indicated that reporting behavior widely varies across crime types with a greater percentage of more serious crimes translated into official crime. Neighborhood characteristics did affect reporting practices, but surprisingly only for more serious forms of disorder where discretion was perceived to be less. The findings lent support for both social disorganization and conflict theories. Theoretical implications are discussed

Four Quarks from Lattice to the Continuum

A continuum extrapolation of static four- and two-quark energies calculated in quenched SU(2) is done based on Sommer's method of setting the scale. A model for four-quark energies with explicit gluonic degrees of freedom removed is fitted to these energies and the behavior of the parameters of the model is investigated.Comment: 4 pages, 3 figures. Talk presented at LATTICE96(phenomenology

Examination of Carotid Arteries with Quantitative Color Doppler Flow Imaging

The results of conventional duplex scanning were compared with QCDFI. A total of 224 consecutive patients comprising 442 unilateral carotid systems were examined by conventional duplex techniques. MPSV, as determined by QCDFI, were recorded for each of the 442 carotid segments and grouped according to the previously determined degrees of stenosis. The predictive value of QCDFI was confirmed by angiography with an overall accuracy of 91%. Results obtained by duplex scanning correlated with angiography 89% of the time. Based on QCDFI data, a scale to grade carotid stenosis was developed

Aggregate and emulsion properties of enzymatically-modified octenylsuccinylated waxy starches

Sorghum and maize waxy starches were hydrophobically modified with octenylsuccinic anhydride (OSA) and treated with enzymes before being used to emulsify β-carotene (beta,beta-carotene) and oil in water. Enzyme treatment with β-amylase resulted in emulsions that were broken (separated) earlier and suffered increased degradation of β-carotene, whereas treatment with pullulanase had little effect on emulsions. Combinations of surfactants with high and low hydrodynamic volume (V) indicated that there is a relationship between V and emulsion stability. Degree of branching (DB) had little direct influence on emulsions, though surfactants with the highest DB were poor emulsifiers due to their reduced molecular size. Results indicate that V and branch length (including linear components) are the primary influences on octenylsuccinylated starches forming stable emulsions, due to the increased steric hindrance from short amphiphilic branches, consistent with current understanding of electrosteric stabilization. The success of OSA-modified sorghum starch points to possible new products of interest in arid climates