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PubMed2001

Developmental profiles of peer social preference over the course of elementary school: associations with trajectories of externalizing and internalizing behavior.

Using a new longitudinal clustering technique, this study aimed to (a) empirically identify groups of children with distinct longitudinal profiles of peer social preference during elementary school; (b) compare these groups regarding their longitudinal pattern of classification into J. D. Coie, K. A. Dodge, and H. Coppotelli's (CDC; 1982) sociometric categories; and (c) compare these groups regarding their longitudinal trajectories of antisocial, hyperactive, and anxious behavior. Based on 299 children, 3 groups were identified: a stable popular group, a stable average group, and an unpopular group whose social preference decreased over time. Each of the groups showed considerable overlap over time with their closest corresponding CDC category (popular, average, rejected). Growth curve analyses showed that externalizing and internalizing behavior generally decreased over time, but overall means and the rates of decrease differed in the 3 groups.

Antisocial Personality Disorder↗
PubMed2002

Developmental trajectories of adolescents' depressive symptoms: predictors of change.

In a sample of 240 adolescents assessed annually in Grades 6 through 11, the developmental trajectories of their depressive symptoms were examined using latent factor growth modeling. Growth in mother-reported adolescent depressive symptoms was quadratic; growth in adolescent-reported symptoms was linear. In the model with gender and maternal depression, girls reported a greater increase in depressive symptoms over time than boys, and adolescents of mothers with histories of mood disorders had higher initial levels of depressive symptoms than offspring of never-depressed mothers. After gender and maternal depression were controlled, initial levels of negative attributions and stressors significantly predicted initial levels of adolescent- and mother-reported depressive symptoms. Attributional styles that were increasingly negative across time were associated with significantly higher initial levels (mother reported) and increasing growth (adolescent reported) of depressive symptoms. Reciprocal models in which development of depressive symptoms predicted the development of attributions and stress also were examined.

Adolescent↗
PubMed2002

A finite mixture model of growth trajectories of adolescent alcohol use: predictors and consequences.

The current study sought to identify classes of growth trajectories of adolescent alcohol use and to examine the predictors and outcomes associated with the classes. Alcohol use was assessed from Grades 7 to 12 in a school-based sample. Latent growth mixture modeling was used, and results indicated 5 discrete longitudinal drinking patterns. The 2 most common drinking patterns included occasional very light drinking from Grades 7 to 12 and moderate escalation in both quantity and frequency of alcohol use. One group drank infrequently but at high levels throughout the study period. Another group exhibited rapid escalation in both quantity and frequency. The final group started at high levels of frequency and quantity in Grade 7 and showed rapid de-escalation in frequency. Emotional distress and risk taking distinguished the classes, and all classes, particularly rapid escalators, showed elevated levels of alcohol-related problems relative to occasional very light drinkers.

Adolescent↗
PubMed1997

Neuroticism, marital interaction, and the trajectory of marital satisfaction.

Theories of how initially satisfied marriages deteriorate or remain stable over time have been limited by a failure to distinguish between key facets of change. The present study defines the trajectory of marital satisfaction in terms of 2 separate parameters--(a) the initial level of satisfaction and (b) the rate of change in satisfaction over time--and seeks to estimate unique effects on each of these parameters with variables derived from intrapersonal and interpersonal models of marriage. Sixty newlywed couples completed measures of neuroticism, were observed during a marital interaction and provided reports of marital satisfaction every 6 months for 4 years. Neuroticism was associated with initial levels of marital satisfaction but had no additional effects on rates of change. Behavior during marital interaction predicted rates of change in marital satisfaction but was not associated with initial levels.

Adult↗
PubMed1990

Accuracy of judging time to arrival: effects of modality, trajectory, and gender.

Observers' accuracy in using time-to-arrival (Ta) information was examined in 4 experiments. The issues included use of visual vs. acoustic Ta information, use of acoustic Ta information by blind Ss, use of Ta information controlling for velocity, and effects of angle of approach and arrival time on judgment accuracy. Visual information was used more efficiently than audiovisual and auditory information. Blind Ss used acoustical approach information as accurately as sighted Ss used visual information. Radial, oblique, and transverse orientations were used to examine effects of approach trajectory. Radial events were underestimated, whereas the more accurate transverse approach was likely to be overestimated. Oblique angle events yielded intermediate accuracies implying a spatiotemporal anisotropy. Women underestimated Ta more than did men. Possible reasons for Ss' judgment accuracy, including linear vs. nonlinear optical changes and relation to spatial skills and experience, were discussed.

Adult↗
PubMed1993

A simple network model simulates hippocampal place fields: II. Computing goal-directed trajectories and memory fields.

Place cells have been described as the computational elements of a neuronal cognitive mapping system that encodes and stores relationships among spatial stimuli (O'Keefe & Nadel, 1978). Furthermore, place cells seem to encode remembered locations because neural activity is maintained when the visual stimuli that influence place field location are vastly degraded, such as when cues are removed or the lights are turned off (O'Keefe & Speakman, 1987; Quirk, Muller, & Kubie, 1990). A feed-forward network model that mapped visual input onto a representation of location simulated some basic properties of hippocampal place fields, including resistance to disruption after partial cue removal (Shapiro & Hetherington, 1993). However, the stimulated place fields required visual input for their activation. We now report that a network that incorporates feedback (a) computed correct trajectories toward simulated goals and (b) simulated place fields that persist in the absence of visual input. The simulation suggests that feedback properties can provide a computational account of O'Keefe and Speakman's data.

Animals↗
PubMed2002

Behavioral change trajectories of partial hospitalization children.

Forecasting treatment outcomes is essential to improving service delivery. Hierarchical linear modeling was used to construct behavioral change trajectories and help predict treatment responsiveness for 97 partial hospitalization children. Overall, children evidenced statistically significant improvement in psychiatric symptomatology. Younger age, female gender, number of previous out-of-home placements, and lower IQ scores were associated with increased psychopathology and poorer treatment response. Properly configured day treatment can provide an effective organizing platform for implementing complex treatment regimes.

Adolescent↗
PubMed2003

The use of latent trajectory models in psychopathology research.

Despite the recent surge in the development of powerful modeling strategies to test questions about individual differences in stability and change over time, these methods are not currently widely used in psychopathology research. In an attempt to further the dissemination of these new methods, the authors present a pedagogical introduction to the structural equation modeling based latent trajectory model, or LTM. They review several different types of LTMs, discuss matching an optimal LTM to a given question of interest, and highlight several issues that might be particularly salient for research in psychopathology. The authors augment each section with a review of published applications of these methods in psychopathology-related research to demonstrate the implementation and interpretation of LTMs in practice.

Data Interpretation, Statistical↗
PubMed2004

Trajectories of alcohol and drug use and dependence from adolescence to adulthood: the effects of familial alcoholism and personality.

This study describes trajectories of substance use and dependence from adolescence to adulthood. Identified consumption groups include heavy drinking/heavy drug use, moderate drinking/experimental drug use, and light drinking/rare drug use. Dependence groups include alcohol only, drug only, and comorbid groups. The heavy drinking/heavy drug use group was at risk for alcohol and drug dependence and persistent dependence and showed more familial alcoholism, negative emotionality, and low constraint. The moderate drinking/experimental drug use group was at risk for alcohol dependence but not comorbid or persistent dependence and showed less negative emotionality and higher constraint. Familial alcoholism raised risk for alcohol and drug use and dependence in part because children from alcoholic families were more impulsive and lower in agreeableness.

Adolescent↗
PubMed2006

Developmental trajectories of co-occurring depressive, eating, antisocial, and substance abuse problems in female adolescents.

Growth trajectories of co-occurring symptomatology were examined in a community sample of 493 female adolescents who were followed annually from early to late adolescence. On average, depression, eating disorder, and substance abuse symptoms increased over time, whereas antisocial behavior decreased. Increases in each symptom domain were associated with relative increases in all other domains. Initial depressive and antisocial behavior symptoms predicted future increases in the other; substance abuse and antisocial behavior symptoms also showed prospective reciprocal relations. Initial depression predicted increases in eating disorder and substance abuse symptoms. Initial eating disorder symptoms predicted increases in substance abuse problems. Finally, the results suggest that the developmental covariation between depressive and eating disorder symptoms and between antisocial behavior and substance abuse symptoms was accounted for by distinct but related 2nd-order growth parameters.

Adolescent↗
PubMed2004

The big five personality traits and individual job performance growth trajectories in maintenance and transitional job stages.

This study extends the literature on personality and job performance through the use of random coefficient modeling to test the validity of the Big Five personality traits in predicting overall sales performance and sales performance trajectories--or systematic patterns of performance growth--in 2 samples of pharmaceutical sales representatives at maintenance and transitional job stages (K. R. Murphy, 1989). In the maintenance sample, conscientiousness and extraversion were positively associated with between-person differences in total sales, whereas only conscientiousness predicted performance growth. In the transitional sample, agreeableness and openness to experience predicted overall performance differences and performance trends. All effects remained significant with job tenure statistically controlled. Possible explanations for these findings are offered, and theoretical and practical implications of findings are discussed.

Adult↗
PubMed2005

Interpersonal predictors of depression trajectories in women with HIV.

This article tests an interpersonal model of depression symptom trajectories tailored to the experiences of women with HIV. Specifically, the authors examined how bereavement, maternal role difficulty, HIV-related social isolation, and partner conflict predicted change in depressive symptoms over 5 years in 761 women with HIV, controlling for sociodemographic and clinical health factors. Of these interpersonal characteristics, partner conflict emerged as a robust predictor of change in depressive symptoms in growth curve and cross-lag models. Results highlight the need for interventions focusing on interpersonal issues, particularly intimate relationships, in women with HIV.

Adolescent↗
PubMed2003

A linear optical trajectory informs the fielder where to run to the side to catch fly balls.

P. McLeod, N. Reed, and Z. Dienes (2002) argued that the linear optical trajectory (LOT) strategy incorrectly cues fielders to run forward for balls headed beyond them. The authors of this article explain that the downward optical curvature found for balls landing beyond the fielder's initial position occurs because the balls reorient the direction the fielder is facing during pursuit. Thus, when downward optical curvature begins, the ball is headed to land in front of where the fielder is facing and running. This investigation of open-loop failure conditions has led to new insights such as the reorientation of the fielder, and it supports the use of maintaining matching rates of vertical and lateral optical ball movement consistent with primacy of the LOT control mechanism even when interception is unachievable.

Cues↗
PubMed1983

Abnormal visual input leads to development of abnormal axon trajectories in frogs.

Throughout the normal vertebrate brain, visual maps form the left and right eyes overlap and are in register with one another. Visual input has a major role in the development of the pathways which mediate these binocular projections. A dramatic example of the developmental role of sensory input occurs in the isthmo-tectal projection, which is part of the polysynaptic relay from the eye to the ipsilateral tectum of the frog, Xenopus laevis. If one eye is rotated when the animal is still a tadpole, the isthmic axons respond by changing the topography of their terminations in the tectum; for example, a given isthmo-tectal axon which normally would connect with medial tectum can be induced to terminate in lateral tectum. Such rearrangements bring the ipsilateral visual map into register with the contralateral retinotectal map, even though one eye has been rotated. Indirect evidence has suggested that after early eye rotation, isthmo-tectal axons do not grow directly to their new tectal targets but instead reach those targets by routes which pass through their normal termination zones. Here I have used anterograde horseradish peroxidase labelling of isthmo-tectal fibres to show the trajectories of such axons and to compare them with the routes which axons take when allowed to develop normally. Tracings of individual axons in flat-mounted, unsectioned tecta show that most axons in normal Xenopus follow fairly straight paths in the tectum. In contrast, early eye rotation causes many isthmo-tectal axons to follow crooked, circuitous pathways before they terminate.

Animals↗
PubMed2000

Real-time prediction of hand trajectory by ensembles of cortical neurons in primates.

Signals derived from the rat motor cortex can be used for controlling one-dimensional movements of a robot arm. It remains unknown, however, whether real-time processing of cortical signals can be employed to reproduce, in a robotic device, the kind of complex arm movements used by primates to reach objects in space. Here we recorded the simultaneous activity of large populations of neurons, distributed in the premotor, primary motor and posterior parietal cortical areas, as non-human primates performed two distinct motor tasks. Accurate real-time predictions of one- and three-dimensional arm movement trajectories were obtained by applying both linear and nonlinear algorithms to cortical neuronal ensemble activity recorded from each animal. In addition, cortically derived signals were successfully used for real-time control of robotic devices, both locally and through the Internet. These results suggest that long-term control of complex prosthetic robot arm movements can be achieved by simple real-time transformations of neuronal population signals derived from multiple cortical areas in primates.

Animals↗
PubMed2006

Quasi-classical trajectories study of Ne79Br2(B) vibrational predissociation.

A full-dimensional quasi-classical trajectories study on the vibrational predissociation (VP) of the Ne79Br2(B) complex is presented. Following the most recent experiments, the Br2(B) vibrational levels v'=16-29 were explored. The total angular momentum, J, was taken to be zero, and a semiclassical Franck-Condon model to compute initial conditions from quantum distributions was employed. Predissociation lifetimes were extracted from Ne79Br2 population decay by using two different exponential laws. Predicted lifetimes are in excellent agreement with the last experimental results [J. A. Cabrera, C. R. Bieler, B. C. Olbricht, W. E. van der Veer and K. C. Janda, J. Chem. Phys., 2005, 123, 054311]. The Br2 fragment ro-vibrational distributions resulting from the VP of the molecule were obtained from the statistics of classical magnitudes using the standard binning procedure. Computed rotational distributions (for the Deltav'=-1, -2 channels) are also in very good agreement with the experimental results [M. Nejad-Sattari and T. A. Stephenson, J. Chem. Phys., 1997, 106 5454]. The influence of two quantum effects-the closing of the Deltav'=-1 dissociation channel and the intramolecular vibrational relaxation (IVR) mechanism-on the agreement with experimental rotational distributions, is discussed. Due to the classical character of our calculations and the binning procedure we used, the agreement of computed vibrational distributions with experimental and quantum theoretical is qualitative. For instance, for v'=28-for which the Deltav'=-1 channel is experimentally found to be closed-the Deltav'=-2 channel becomes statistically more significant. A discussion on the viability of similar quasi-classical methods to model the VP dynamics of analogous clusters is presented.

Journal Article↗
PubMed1998

Speaking-rate-induced variability in F2 trajectories.

This study examined speaking-rate-induced spectral and temporal variability of F2 formant trajectories for target words produced in a carrier phrase at speaking rates ranging from fast to slow. F2 onset frequency measured at the first glottal pulse following the stop consonant release in target words was used to quantify the extent to which adjacent consonantal and vocalic gestures overlapped; F2 target frequency was operationally defined as the first occurrence of a frequency minimum or maximum following F2 onset frequency. Regression analyses indicated 70% of functions relating F2 onset and vowel duration were statistically significant. The strength of the effect was variable, however, and the direction of significant functions often differed from that predicted by a simple model of overlapping, sliding gestures. Results of a partial correlation analysis examining interrelationships among F2 onset, F2 target frequency, and vowel duration across the speaking rate range indicated that covariation of F2 target with vowel duration may obscure the relationship between F2 onset and vowel duration across rate. The results further suggested that a sliding based model of acoustic variability associated with speaking rate change only partially accounts for the present data, and that such a view accounts for some speakers' data better than others.

Female↗