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Since the typical account longevity is short, agencies should anticipate their likelihood of loss, seek to forestall and invest in their client relationships. A model is proposed for examining account lifetimes, which can offer guidance on the likely retention of future accounts. The impact of agency structural characteristics on longevity is also examined, and compared for both U.S. and U.K. markets. Results for both markets indicate that cumulative account dissolution increases at a decreasing rate over time. Greater account longevity is associated with larger agency size (both in terms of agency billings and employees), and agency age but not with stability of billings growth. Evidence suggests that several structural characteristics of agencies reflect the motivation and/or ability to maintain accounts. © 1999 Taylor & Francis Group, LLC.

To investigate emotion expression and personality relations, the authors coded infants' full-face and component positive and negative expressions during Episodes 4 through 8 of the strange situation procedure at age 18 months and obtained maternal ratings of the 5-factor model of personality when children were 3.5 years old. Full-face negative expression was directly related to Neuroticism and inversely related to Agreeableness and Conscientiousness. By contrast, component positive expression showed the exact opposite pattern of relations. Full-face positive expression was positively correlated with Extraversion and Openness to Experience. These findings indicate that full-face and component expressions may index different intensities of emotions. Emotion expression and personality relations were not mediated by the security of attachment continuum or the emotional reactivity dichotomy derived from the attachment subclassifications.

A substantial body of theoretical literature testifies to the evolutionary functions of emotions. Relatively little has been written about their developmental functions. This article discusses the developmental functions of emotions from the perspective of differential emotions theory (DET; Izard, 1977, 1991). According to DET, although all the emotions retain their adaptive and motivational functions across the lifespan, different sets of emotions may become relatively more prominent in the different stages of life as they serve stage-related developmental processes. In the first section, we present a brief overview of relevant aspects of the theory. In the second section, we discuss how emotions play a central role in helping the individual achieve developmental milestones and tasks during four major periods of life: Infancy, toddler through preschool years, middle to late childhood, and adolescence. The underlying thesis of this article is that emotions play a central role in stimulating social cognitive attainments at each stage of development. © 1999 Psychology Press Ltd.

Based on Singer's (1986) method, we investigated the effects of a four- step strategy (ready, look, do, score) on training, maintenance, and generalization of three closed skills (basketball free throw, overhand softball throw, and dart throw) by adolescents (M age = 17.2) with mild mental retardation (MR). A multiple baseline across skills design was used. Performances of 3 males and 3 females across these three skills were examined. Participants averaged a total of 46 sessions for the duration of the study. Results indicated that participants increased performance 18-56% across all three closed skills during the training phase. A total of 4 participants maintained performance on all three skills when reminders were present, and 2 decreased performance when the reminders were removed. All participants exhibited improved performance when a reinforcer was introduced. Moreover, 5 participants were able to generalize the four-step strategy to a different setting.

In recent years, violence has been a major concern for human service professionals and increasingly, to child and youth care workers particularly as they have served in schools where major violent events have occurred. Most often violence prevention and intervention efforts ignore the systemic aspects of violence and are too narrowly focused. This article proposes that a consideration of violence in schools be based on dynamical systems theory. This theory offers rich possibilities for generating a useful model for mediating school violence and for suggesting ways in which child and youth care workers can use their competencies to address the multiple factors related to school violence. The article includes an overview to the concepts of dynamical systems theory, offers the dynamical systems model for mediating school violence and presents implications for the roles and functions of child and youth workers particularly in the emerging area of school based child and youth care work. © 1999 Human Sciences Press, Inc.

Temporal analysis has been applied to a sequence of cloud top pressure (CTP) images and cloud optical thickness (TAU) images stored in the International Satellite Cloud Climatology Project (ISCCP) D1 database located at the NASA Goddard Institute for Space Studies (GISS). Each pixel in the D1 data set has a resolution of 2.5 degrees or 280 kilometers. These images were collected in consecutive three-hour intervals for the entire month of April 1989. The primary objective of this project was to develop a sequence of storm tracks from the satellite images to follow the formation, progression and dissipation of storm systems over time. Composite images where created by projecting ahead in time and substituting the first available valid pixel for missing data and a variety of CTP and TAU cut-off values were used to identify regions of interest. Region correspondences were determined from one time frame to another yielding the coordinates of storm centers. These tracks were compared to storm tracks computed from sea level pressure data obtain from the National Meteorological Center (NMC) for the same time period. The location of sea level storm center provides insight as to whether storms have occurred anywhere in a region and can be helpful in determining the presence or absence of storms in a general geographic region.

The primary objective of this project is to define a methodology to depict the motion of deep convective cloud systems as observed form satellite imagery. These clouds are defined as clusters of pixels with Cloud Top Pressure (IPC) <EQ 440 millibars and Cloud Optical Thickness (TAU) >= 23 which are high in the atmosphere and sufficiently thick to produce significant rainfall. Clouds are one of the major factors in understanding the earth's climate. Evaluating cloud motion is important in understanding atmospheric dynamics and visualizations are vital because they provide a good way to observe change. IPC and TAU values have been collected for April of 1989 from the International Satellite Cloud Climatology Project, low resolution database for the northern latitudes between 30 and 60 degrees. Each of the 240 IPC and 240 TAU images consisted of 12 rows and 144 columns with each pixel representing a 280 km square on the globe collected in three-hour intervals. Individual images were color coded according to land, sea and clouds before being put into motion. Six animations have been produced which start with the original images, progress to include daily composite images and culminate with a collage. Animations of the original images have the advantage of relatively short intervals between still frames but have many undefined pixels, which are eliminated in the composites. The results of this project can serve as an example of how to improve the visualization of time varying image sequences.

The objective of this study is to compare statistical and unsupervised neural network techniques for determination of correspondences between storm system regions extracted from sequences of satellite images. Analysis was applied to the International Satellite Cloud Climatology Project (ISCCP) low resolution D1 database for selected storm systems during the period April 5 - 9, 1989. Cloud top pressure was used to delineate regions of interest and cloud optical thickness combined with spatial location was used to track regions throughout a given time sequence. The ability of the k-nearest neighbor classifier and of self-organizing maps to determine correspondences between storm regions was assessed. The two techniques generally yielded similar associations between regions of interest throughout the time sequence. Differences in final tracking results between the two techniques occurred primarily as a result of differences in the collections of points from a region in a time step t<SUB>2</SUB> that corresponded to a region in an earlier time step t<SUB>1</SUB>. The tracking results were also compared to the results obtained at the NASA Goddard Institute for Space Studies using sea level pressure data from the National Meteorological Center (NMC). For the storm systems investigated in this study, the storm tracks exhibited the same general tracking behavior with expected variations between cloud system storm centers and low sea level pressure centers.

A view of interactions in the undergraduate classroom is presented from several perspectives. Topics discussed include class perceptions of teacher as facilitator/authority/leader, grades versus performance appraisals, mixed-gender interactions, and subtle forms of cultural variations.

Accurate identification and tracking of synoptic-scale storm systems in the northern midlatitudes is important for understanding the structure and movement of the midlatitude cloud field which plays a major role in climate change. In this paper, a hybrid neural network/genetic algorithm (NN/GA) approach is presented that analyzes the behavior of storm systems from one time frame to the next. The goal of the hybrid neural network algorithm is to improve classifier output by reducing the number of infeasible solutions using constraint optimization techniques. The input to the hybrid neural network algorithm is the output from a traditional backpropagation neural network. The hybrid NN/GA analyzes the backpropagation neural network output for logical consistencies and makes changes to the classification results based on strength of neural network classifications and satisfaction of logical constraints. The results are compared with classification results obtained using linear discriminant analysis, k-nearest neighbor rule, and backpropagation neural network techniques.

An evolutionary system was developed for generation of complete tracks of northern midlatitude synoptic-scale storm systems based on optical flow and cloud motion analyses of global satellite-based datasets produced by the International Satellite Cloud Climatology Project (ISCCP). The tracking results were compared with low sea level pressure anomaly (SLPA) tracks obtained from the NASA Goddard Institute for Space Studies (GISS). The SLPA tracks were produced at GISS by analysis of meteorological, ground-based National Center for Environmental Prediction (NCEP) datasets. Results from the evolutionary system were also compared with results from using (a) the k-nearest neighbor rule (k-NN) and (b) self-organizing maps (SOM) to determine correspondences between consecutive locations within a track. The consistency of our evolutionary storm tracking results with the behavior of the low sea level pressure anomaly tracks, the ability of our evolutionary system to generate and evaluate complete tracks, and the close comparison between the results obtained by the evolutionary, k-NN, and SOM analyses of the ISCCP-derived datasets at tracking steps in which proximity or optical flow information sufficed to determine movement, demonstrate the applicability and the potential of evolutionary systems for tracking midlatitude storm systems through low-resolution ISCCP cloud product datasets.

This article discusses the integration of various aspects of the child's development, particularly the development of language and communication and the way in which these developments interact to enable the child to construct a coherent sense of self. Multiplex developmental disorder is presented as an example of a disorder that affects several of these crucial strands of development. Recent research and controversies regarding the diagnostic descriptions of multiplex and other pervasive developmental disorders are presented. This discussion is used to illustrate the ways in which such disorders affect not only the individual aspects of development, but the child's ability to form a cohesive sense of self. The implications of these difficulties in self-definition for treating children with disorders that affect a variety of aspects of development are also discussed.

This article examines the communication styles of children with mental retardation, emphasizing the assessment and intervention protocols used by health and education professionals. This article highlights the following approaches: a developmental psycholinguistic orientation, a pragmatics approach, and a supportive interdependent format consistent with the 1992 revision of how mental retardation is classified. This article discusses children with mental retardation who show challenging and disruptive behavior.

This article presents issues related to the communication assessment of children with psychiatric and communication disorders. Challenges inherent in assessing this population are discussed. Frequently used assessment instruments and procedures are described. Consideration is given to the assessment of very young or low-functioning children and older or high-functioning children.