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PubMed2026

Early-stage trajectories of social-occupational functioning and long-term functional outcome prediction in early psychosis: A 12-year follow-up of the randomized controlled trial on extended early intervention.

BACKGROUND: Functional impairment in psychosis often persists despite symptomatic remission. There is a paucity of research examining early-course psychosocial functioning trajectories, and none has been conducted to examine relationship between the trajectories and prospective long-term functional outcomes in early psychosis sample. METHODS: We conducted 12-year follow-up of a randomized controlled trial on extended early intervention for first-episode psychosis to identify early-course social-occupational functioning trajectories and their baseline predictors and associations with 12-year outcomes. Participants who completed Social and Occupational Functioning Scale (SOFAS) scores at three or more timepoints between baseline and 3-year follow-up were included in the study. Premorbid adjustment, illness characteristics, symptom severity, functioning, and treatment profiles were assessed. Latent growth mixture modeling was employed to derive early-course social-occupational functioning trajectories based on SOFAS scores over 3-year follow-up. RESULTS: A total of 148 participants were included in this study, with 106 patients having completed the 12-year follow-up. Our results identified four distinct trajectories, including persistently-good class, gradually-improved class, suboptimal-stable class, and persistently-poor class. Patients in persistently-poor class had more severe negative symptoms at baseline compared to patients in persistently-good class. Patients with persistently-poor trajectory had worse long-term outcomes than those with other classes in the majority of functional measures at 12-year follow-up. CONCLUSIONS: The majority of patients were classified in early-stage suboptimal or poor functional trajectories. Above one-fourth of the participants exhibited persistently-poor social-occupational functioning trajectory, which predicted worse functional outcomes at 12-year follow-up. These findings highlighted the importance of tracking functional changes during the initial years of illness.

Humans↗
PubMed2000

Wound healing trajectories as predictors of effectiveness of therapeutic agents.

BACKGROUND: One goal of wound healing research is to discover agents to accelerate healing. Regulatory agencies have suggested stringent criteria to determine efficacy, that of 100% wound closure. Data analysis at a single point such as 100% closure does not provide detailed information about agent effectiveness over the entire span of healing. HYPOTHESIS: Wound healing trajectories can provide such information and can be used to demonstrate utility as alternative end points for wound healing trials. DESIGN: Data from 160 patients in 11 clinical trials of diabetic foot ulcers conducted at 2 centers were evaluated. Wound healing trajectories were constructed for patients whose wounds healed (100% closure) and those whose did not (<100% closure) over a 20-week period. The percentage of patients achieving total healing vs time of treatment was plotted and divided into patients receiving a test agent or placebo. RESULTS: The healing trajectories were almost identical for patients achieving complete healing at the 2 centers, as were the trajectories for patients with less than 100% closure. However, the trajectories of patients achieving total healing were significantly different from those not achieving 100% closure. Fifty-two percent of all patients achieved 100% healing by 20 weeks; 61% of patients receiving an experimental agent had total healing compared with 39% of placebo-treated patients. Linear regression suggested that all patients would achieve total healing by 37 weeks. CONCLUSIONS: Since wound healing trajectories for diabetic foot ulcers treated at 2 centers so closely mimic one another, trajectories might be useful efficacy end points, and used to compare significant points along a continuum rather than a single static end point. Shifting of the wound healing trajectory from an impaired to a more ideal course may be considered when determining efficacy of new wound treatments.

Debridement↗
PubMed2004

Optimal design of k-space trajectories using a multi-objective genetic algorithm.

Spiral, radial, and other nonrectilinear k-space trajectories are an area of active research in MRI due largely to their typically rapid acquisition times and benign artifact patterns. Trajectory design has commonly proceeded from a description of a simple shape to an investigation of its properties, because there is no general theory for the derivation of new trajectories with specific properties. Here such a generalized methodology is described. Specifically, a multi-objective genetic algorithm (GA) is used to design trajectories with beneficial flow and off-resonance properties. The algorithm converges to a well-defined optimal set with standard spiral trajectories on the rapid but low-quality end, and a new class of trajectories on the slower but high-quality end. The new trajectories all begin with nonzero gradient amplitude at the k-space origin, and curve gently outward relative to standard spirals. Improvements predicted in simulated imaging experiments were found to correlate well with improvements in actual experimental measures of image quality. The impact of deviations from the desired k-space trajectory is described, as is the impact of using different phantoms.

Algorithms↗
PubMed1999

Kinematic construction of the trajectory of sequential arm movements.

A kinematic construction rule determining the trajectory of human sequential movements is formulated using minimum-jerk and minimum-angular-jerk trajectories. The kinematic construction rule states that the observed trajectory of sequential movements coincides with a weighted average of the minimum-jerk trajectory and the segmented minimum-angular-jerk trajectory. This rule covers not only point-to-point movements but also simple sequential movements. Five kinds of experiments that measure the trajectories in planar, multijoint sequential arm movements were conducted. The measured trajectories coincide with the predictions made on the basis of the kinematic construction rule presented here. Moreover, predictions of previous models such as the minimum-jerk, the equilibrium-trajectory, and the minimum-torque-change models are shown to be incompatible with our observations of sequential movements.

Arm↗
PubMed2005

Smoking trajectories of adolescent novice smokers in a longitudinal study of tobacco use.

PURPOSE: To describe longitudinal trajectories of smoking intensity in adolescent novice smokers and to identify predictors of trajectory class membership. METHODS: Cigarette consumption among 369 novice smokers (mean age 13 years) was measured over a mean 24 months of follow-up after smoking onset. Classes of smoking intensity trajectories were identified using latent class growth modeling. Predictors of trajectory class membership were identified in polytomous logistic regression. RESULTS: There was considerable between-subject heterogeneity in individual trajectories over time. Four classes of smoking intensity trajectories were identified: low-intensity, non-progressing smokers (72.4% of subjects), and slow, moderate, and rapid escalators (11.1%, 10.8%, and 5.7% of subjects, respectively). Gender, poor academic performance, and having more than half of friends who smoke at smoking onset independently predicted development of trajectory pattern. Escalating trajectory patterns were associated with earlier development of nicotine dependence and tolerance. CONCLUSIONS: Cigarette consumption will not escalate rapidly among three-quarters of adolescent novice smokers. Novice smokers who do escalate rapidly should be targeted for early tobacco control intervention to prevent development of nicotine dependence and sustained smoking.

Adolescent↗
PubMed2004

Trajectories of depressive symptoms among high risk African-American adolescents.

PURPOSE: To examine the trajectories of depressive symptoms among African-American youth and the psychosocial factors associated with these trajectories. METHODS: The sample included 579 African-American adolescents who were at risk of dropping out of school, interviewed annually starting from ninth grade for 4 years. The measures included depressive symptoms, anxiety symptoms, self-esteem, stress, and active coping; all self-reported. We used cluster analysis to develop longitudinal trajectories of depression in our sample. RESULTS: Four different trajectories of depressive symptoms were found that represented the changes in depressive symptoms among the participants. These trajectories are: consistently high (15.9%), consistently low (21.1%), decreasing (41.8%), and increasing (21.2%) depressive symptoms. The results from the comparisons of the trajectories indicated that adolescents who presented consistently high levels of depressive symptoms were more likely to be female, reported more anxiety symptoms, lower self-esteem, higher stress, and lower grade point average (GPA) compared with adolescent members of the other trajectories. DISCUSSION: Depressive symptoms may be manifested in different ways according to the patterns of change. Different correlates are associated with these trajectories of depressive symptoms and provide insights about the antecedents and consequences of the patterns of change in depressive symptoms.

Adaptation, Psychological↗
PubMed2006

Developmental trajectories of family management and risk for violent behavior in adolescence.

PURPOSE: To address two questions: (1) Can groups of family management trajectories be identified in early adolescence? (2) How are the different family management trajectories related to trajectories of violent offending for youths aged 13-18 years? METHODS: Analyses used semi-parametric group-based modeling (SGM) to identify groups of family management trajectories. A joint trajectory method was used to predict patterns of youth violence conditional on family management. RESULTS: Analyses identified 3 trajectories of family management from age 11 to 14: (1) stable low, (2) stable high, and (3) increasing family management. Youths from families in the low family management trajectory were more likely than others to follow chronic and late increasing trajectories of violence. In contrast, youths in stable-high positive family management were less likely to engage in violence from age 13 to age 18. Further, youths whose families started low, but increased to high family management, had patterns of adolescent violence similar to those whose parents were consistently high in their use of good parenting practices. CONCLUSIONS: The current study advances knowledge of developmental patterns in family management and youth violence. Although most parents remained stable in family management practices from age 11 to 14 (stable high or stable low), parents who started low, but improved their management practices during middle school, had children with lower levels of chronic and late increasing violence than those who remained low. Findings suggest that interventions developed to enhance family management practices may reduce risk for violence in later adolescence.

Adolescent↗
PubMed2005

Nondisease factors affected trajectories of disability in a prospective study.

OBJECTIVE: To examine nondisease factors, including sociodemographic variables, health behaviors and psychosocial factors as determinants of trajectories of disability. STUDY DESIGN AND SETTING: We used a classification of 10 trajectories of disability based on a multiround prospective study design; nine trajectories grouped survivors with a similar level and time course of disability, one included all deaths. Multinomial logistic regression was used to assess associations between these trajectories and a wide range of nondisease factors. RESULTS: Correcting for age, sex, and four chronic diseases, we found that sociodemographic factors (education and income), health behaviors (leisure-time physical activity and BMI), and psychosocial factors (locus of control, neuroticism, and active problem focusing) were significantly associated with the trajectories of disability. Moreover, our results pointed to factors associated with disability trajectories that were characterized by sudden increase (external locus of control and, to a lesser extent, BMI), strong fluctuations (neuroticism, BMI, external locus of control), or high severity (leisure-time physical inactivity) of disability. CONCLUSION: A wide range of nondisease factors is associated with the trajectories of disability. Preventing obesity, developing a more internal locus of control, and increasing physical activity could contribute to preventing trajectories characterized by rapid decline, large fluctuations or severe disability. Understanding the role of these factors should receive high priority.

Adolescent↗
PubMed2005

Perception of motion trajectory of object from the moving cast shadow in infants.

A moving cast shadow of the object affects the perception of the object's trajectory in adults [Kersten, D., Mamassian, P., & Knill, D. C. (1997). Moving cast shadow induce apparent motion in depth. Perception, 26, 171-192]. In the present study, we investigated by using a habituation-dishabituation procedure whether infants at 4- to 7-months old discriminate the motion trajectory of a ball from the moving shadow it casts. In Experiment 1, 4- to 5-month-old and 6- to 7-month-old were tested for ability to discriminate between a "depth" display containing a ball and a cast shadow with a diagonal trajectory and an "up" display containing a ball with a diagonal trajectory and a cast shadow with a horizontal trajectory. Six- and 7-month-old, but not 4- and 5-month-old, infants looked significantly longer at the "up" display than at the "depth" display. In Experiment 2, we tested whether 4- to 5-month-old and 6- to 7-month-old infants would perceive "up" motion as categorically different from "depth" depending on the object's 3-D trajectory. We used displays containing a ball and a cast shadow with the same trajectories as those in Experiment 1 except that the cast shadows appeared above the ball. These displays did not produce 3-D impressions in adults. Neither age group of infants exhibited significant differences between "up" and "depth" displays. When the results from the two experiments are considered, 6- and 7-month-old infants discriminated the motion trajectory of the ball from the moving cast shadows. This developmental emergence of depth perception from a moving cast shadow at 6 months of age is consistent with that of other pictorial depth cues.

Aging↗
PubMed1999

Correlation between planned prosthetic and residual bone trajectories in dental implants.

STATEMENT OF PROBLEM: The success of dental implant treatment relies on a well-developed treatment plan approach. Historically, implant placement was guided mainly by residual bone height and width, at times compromising prosthetic needs. PURPOSE: This study analyzed the amount of deviation between planned prosthetic trajectory and residual bone trajectory in different areas of the maxillary and mandibular dental arches, by using a tomographic survey in conjunction with imaging/surgical guides. METHODS AND MATERIAL: Ninety-two patients with a total of 235 implant sites were selected for the study. An imaging and surgical guide with a radiopaque indicator was constructed to determine the planned prosthetic trajectory. Cross-sectional tomograms were taken through the indicator at each implant site. The outlines of the available bone, planned prosthetic trajectory, and residual bone trajectory were traced, and the difference in the trajectory between the 2 trajectories was determined. RESULTS: Discrepancies between the planned prosthetic and the residual bone trajectories were greater in the mandibular molar area. This site was statistically different from other site groups at P =.05 (Tukey method). Statistically, all other site groups were not significantly different.

Analysis of Variance↗
PubMed1999

Local motion detectors cannot account for the detectability of an extended trajectory in noise.

Previous work has shown that a single dot moving in a consistent direction is easily detected among noise dots in Brownian motion (Watamaniuk et al., Vis Res 1995;35:65-77). In this study we calculated the predictions of a commonly-used psychophysical motion model for a motion trajectory in noise. This model assumes local motion energy detectors optimally tuned to the signal, followed by a decision stage that implements the maximum rule. We first show that local motion detectors do indeed explain the detectability of brief trajectories (100 ms) that fall within a single unit, but that they severely underestimate the detectability of extended trajectories that span multiple units. For instance, a 200 ms trajectory is approximately three times more detectable than two isolated 100 ms trajectories presented together within an equivalent temporal interval. This result suggests a nonlinear interaction among local motion units. This interaction is not restricted to linear trajectories because circular trajectories with curvatures larger than 1 degree are almost as detectable as linear trajectories. Our data are consistent with a flexible network that feeds forward excitation among units tuned to similar directions of motion.

Humans↗
PubMed2006

Comparison of the Newtonian and relativistic predicted trajectories for a low-speed periodically delta-kicked system.

The dynamics of a periodically delta-kicked Hamiltonian system moving at low speed (i.e., at speed much less than the speed of light) is studied numerically. In particular, the trajectory of the system predicted by Newtonian mechanics is compared with the trajectory predicted by special relativistic mechanics for the same parameters and initial conditions. We find that the Newtonian trajectory, although close to the relativistic trajectory for some time, eventually disagrees completely with the relativistic trajectory, regardless of the nature (chaotic, nonchaotic) of each trajectory. However, the agreement breaks down very fast if either the Newtonian or relativistic trajectory is chaotic, but very much slower if both the Newtonian and relativistic trajectories are nonchaotic. In the former chaotic case, the difference between the Newtonian and relativistic values for both position and momentum grows, on average, exponentially. In the latter nonchaotic case, the difference grows much slower, for example, linearly on average.

Models, Statistical↗
PubMed1998

Saccade-vergence trajectories under free- and instrument-space environments.

PURPOSE: The purpose of this study was to examine in detail the binocular fixation top-view trajectories of saccade-vergence responses to asymmetrical targets, and to compare latency difference between saccade and vergence, under the free- and instrument-space viewing environments. METHODS: Binocular eye movements were recorded using the infrared reflection technique in five visually-normal subjects. Responses were obtained for various asymmetrical target positions under both free- and instrument-space environments. RESULTS: Four types of top-view trajectories that represented normal variations in saccade and vergence control were found: straight, overshoot, undershoot, and saccade-vergence. Also, it was found that under the instrument-space environment, there was a predominance of saccade-vergence trajectories and a scarcity of overshoot trajectories, whereas under the free-space environment, there was a predominance of overshoot trajectories, and a scarcity of saccade-vergence trajectories. Further, under the instrument-space environment, latency was significantly longer for saccade than vergence (35.9 +/- 15.7 msec; t = 5.1, degrees of freedom (df) = 4, P < 0.01), whereas under the free-space environment, there was no latency difference (-10.5 +/- 14.8 msec; = -1.6, df = 4, P > 0.05). CONCLUSIONS: The differences in response profiles under the two viewing environments could be accounted for by differences in timing of saccade and vergence onset. Moreover, in contrast to some recent investigations that suggest higher center control of individual trajectories, which was dependent on the naturalistic scene, these trajectories could be accounted for by known neural and oculomotor mechanisms, with the higher centers using a priori information about spatial location of the target, to assist in the synchrony of saccade and vergence onset under the free-space environment.

Adult↗
PubMed2005

Directional biases in back trajectories caused by model and input data.

Back trajectory analyses are often used for source attribution estimates in visibility and other air quality studies. Several models and gridded meteorological datasets are readily available for generation of trajectories. The Big Bend Regional Aerosol and Visibility Observational (BRAVO) tracer study of July to October 1999 provided an opportunity to evaluate trajectory methods and input data against tracer concentrations, particulate data, and other source attribution techniques. Results showed evidence of systematic biases between the results of different back trajectory model and meteorological input data combinations at Big Bend National Park during the BRAVO. Most of the differences were because of the choice of meteorological data used as input to the trajectory models. Different back trajectories also resulted from the choice of trajectory model, primarily because of the different mechanisms used for vertical placement of the trajectories. No single model or single meteorological data set was found to be superior to the others, although rawinsonde data alone are too sparse in this region to be used as the only input data, and some combinations of model and input data could not be used to reproduce known attributions of tracers and simulated sulfate.

Air Pollutants↗
PubMed2004

Identifying and predicting adolescent smokers' developmental trajectories.

Very few studies have defined trajectories of smoking. In the present study, we modeled growth in adolescent smoking and empirically identified prototypical trajectories. We conceptualized escalation of smoking as a growth process and modeled rates of change and heterogeneity of these patterns using latent growth mixture modeling. The analysis identified six trajectories with low ambiguity about group membership (early rapid escalators, late rapid escalators, late moderate escalators, late slow escalators-smokers, stable puffers, and late slow escalators-puffers). A trajectory of quitters was not identified. We also examined predictors of the smoking trajectories. The predictors were assessed across the adolescent years and included variables related to smoking and other substance use, as well as a range of variables related to sociodemographic factors and mental health. Observed change in the pattern of predictors across age has implications for the mechanism of effect of these variables in relation to smoking trajectories, including predictors that differentiated among daily smokers, variables that may determine the trajectory (e.g., friends smoking), and variables that may result from the trajectory (e.g., marijuana use, less attachment to friends).

Adolescent↗
PubMedDate not supplied

Treatment-seeking delay among women with acute myocardial infarction: decision trajectories and their predictors.

BACKGROUND: Women's delay in seeking treatment for acute myocardial infarction symptoms results in higher rates of mortality and morbidity for women. OBJECTIVES: To describe decision trajectories used by women when experiencing symptoms of acute myocardial infarction, and to identify predictors of the decision trajectory used by women with acute myocardial infarction. METHODS: A cross-sectional, descriptive design was used. The nonprobability sample included 52 women hospitalized for acute myocardial infarction. To elicit descriptions of decision making, focused, semistructured interviews were used in this mixed-methods study. Predictors of decision trajectories were measured with standardized instruments among the same women. Narrative analysis was used to examine the stories from the qualitative data and to identify decision trajectory types. Discriminant analysis was used to predict trajectory type membership. RESULTS: The median delay time was 4.25 hours. Most of the women used one of two trajectory types: knowing (defined as those women who knew almost immediately that they would seek help, n = 25) and managing (those women who managed an alternative hypothesis or minimized their symptoms, n = 23). Discriminant analysis correctly classified 71% (chi [4] = 11.2; n = 48; p =.02) of the cases into trajectory types on the basis of four predictor variables: social support, personal control, heart disease threat, and neuroticism. DISCUSSION: Women's behaviors during the period between onset of acute myocardial infarction symptoms and treatment seeking can be categorized into a small number of patterns termed decision trajectories. A profile of sociostructural and intrapersonal factors with potential for predicting behavior in relation to future coronary events was developed.

Adult↗
PubMed2004

A hierarchical self-organizing approach for learning the patterns of motion trajectories.

The understanding and description of object behaviors is a hot topic in computer vision. Trajectory analysis is one of the basic problems in behavior understanding, and the learning of trajectory patterns that can be used to detect anomalies and predict object trajectories is an interesting and important problem in trajectory analysis. In this paper, we present a hierarchical self-organizing neural network model and its application to the learning of trajectory distribution patterns for event recognition. The distribution patterns of trajectories are learnt using a hierarchical self-organizing neural network. Using the learned patterns, we consider anomaly detection as well as object behavior prediction. Compared with the existing neural network structures that are used to learn patterns of trajectories, our network structure has smaller scale and faster learning speed, and is thus more effective. Experimental results using two different sets of data demonstrate the accuracy and speed of our hierarchical self-organizing neural network in learning the distribution patterns of object trajectories.

Learning↗
PubMed2003

Effects of speaking rate on second formant trajectories of selected vocalic nuclei.

The effect of speaking rate variations on second formant (F2) trajectories was investigated for a continuum of rates. F2 trajectories for the schwa preceding a voiced bilabial stop, and one of three target vocalic nuclei following the stop, were generated for utterances of the form "Put a bV here, where V was /i/,/ae/ or /oI/. Discrete spectral measures at the vowel-consonant and consonant-vowel interfaces, as well as vowel target values, were examined as potential parameters of rate variation; several different whole-trajectory analyses were also explored. Results suggested that a discrete measure at the vowel consonant (schwa-consonant) interface, the F2off value, was in many cases a good index of rate variation, provided the rates were not unusually slow (vowel durations less than 200 ms). The relationship of the spectral measure at the consonant-vowel interface, F2 onset, as well as that of the "target" for this vowel, was less clearly related to rate variation. Whole-trajectory analyses indicated that the rate effect cannot be captured by linear compressions and expansions of some prototype trajectory. Moreover, the effect of rate manipulation on formant trajectories interacts with speaker and vocalic nucleus type, making it difficult to specify general rules for these effects. However, there is evidence that a small number of speaker strategies may emerge from a careful qualitative and quantitative analysis of whole formant trajectories. Results are discussed in terms of models of speech production and a group of speech disorders that is usually associated with anomalies of speaking rate, and hence of formant frequency trajectories.

Adult↗