Inattention/hyperactivity and aggression from early childhood to adolescence: Heterogeneity of trajectories and differential influence of family environment characteristics

PubMed Central

JESTER, JENNIFER M.; NIGG, JOEL T.; ADAMS, KENNETH; FITZGERALD, HIRAM E.; PUTTLER, LEON I.; WONG, MARIA M.; ZUCKER, ROBERT A.

2008-01-01

In attention/hyperactivity and aggressive behavior problems were measured in 335 children from school entry throughout adolescence, at 3-year intervals. Children were participants in a high-risk prospective study of substance use disorders and comorbid problems. A parallel process latent growth model found aggressive behavior decreasing throughout childhood and adolescence, whereas inattentive/hyperactive behavior levels were constant. Growth mixture modeling, in which developmental trajectories are statistically classified, found two classes for inattention/hyperactivity and two for aggressive behavior, resulting in a total of four trajectory classes. Different influences of the family environment predicted development of the two types of behavior problems when the other behavior problem was held constant. Lower emotional support and lower intellectual stimulation by the parents in early childhood predicted membership in the high problem class of inattention/hyperactivity when the trajectory of aggression was held constant. Conversely, conflict and lack of cohesiveness in the family environment predicted membership in a worse developmental trajectory of aggressive behavior when the inattention/hyperactivity trajectories were held constant. The implications of these findings for the development of inattention/hyperactivity and for the development of risk for the emergence of substance use disorders are discussed. PMID:15971762

(Re)evaluating the Implications of the Autoregressive Latent Trajectory Model Through Likelihood Ratio Tests of Its Initial Conditions.

PubMed

Ou, Lu; Chow, Sy-Miin; Ji, Linying; Molenaar, Peter C M

2017-01-01

The autoregressive latent trajectory (ALT) model synthesizes the autoregressive model and the latent growth curve model. The ALT model is flexible enough to produce a variety of discrepant model-implied change trajectories. While some researchers consider this a virtue, others have cautioned that this may confound interpretations of the model's parameters. In this article, we show that some-but not all-of these interpretational difficulties may be clarified mathematically and tested explicitly via likelihood ratio tests (LRTs) imposed on the initial conditions of the model. We show analytically the nested relations among three variants of the ALT model and the constraints needed to establish equivalences. A Monte Carlo simulation study indicated that LRTs, particularly when used in combination with information criterion measures, can allow researchers to test targeted hypotheses about the functional forms of the change process under study. We further demonstrate when and how such tests may justifiably be used to facilitate our understanding of the underlying process of change using a subsample (N = 3,995) of longitudinal family income data from the National Longitudinal Survey of Youth.

The Development of Future Orientation is Associated with Faster Decline in Hopelessness during Adolescence.

PubMed

Mac Giollabhui, Naoise; Nielsen, Johanna; Seidman, Sam; Olino, Thomas M; Abramson, Lyn Y; Alloy, Lauren B

2018-01-05

Hopelessness is implicated in multiple psychological disorders. Little is known, however, about the trajectory of hopelessness during adolescence or how emergent future orientation may influence its trajectory. Parallel process latent growth curve modelling tested whether (i) trajectories of future orientation and hopelessness and (ii) within-individual change in future orientation and hopelessness were related. The study was comprised of 472 adolescents [52% female, 47% Caucasian, 47% received free lunch] recruited at ages 12-13 who completed measures of future orientation and hopelessness at five annual assessments. The results indicate that a general decline in hopelessness across adolescence occurs quicker for those experiencing faster development of future orientation, when controlling for age, sex, low socio-economic status in addition to stressful life events in childhood and adolescence. Stressful childhood life events were associated with worse future orientation at baseline and negative life events experienced during adolescence were associated with both an increase in the trajectory of hopelessness as well as a decrease in the trajectory of future orientation. This study provides compelling evidence that the development of future orientation during adolescence is associated with a faster decline in hopelessness.

What develops during emotional development? A component process approach to identifying sources of psychopathology risk in adolescence

PubMed Central

McLaughlin, Katie A.; Garrad, Megan C.; Somerville, Leah H.

2015-01-01

Adolescence is a phase of the lifespan associated with widespread changes in emotional behavior thought to reflect both changing environments and stressors, and psychological and neurobiological development. However, emotions themselves are complex phenomena that are composed of multiple subprocesses. In this paper, we argue that examining emotional development from a process-level perspective facilitates important insights into the mechanisms that underlie adolescents' shifting emotions and intensified risk for psychopathology. Contrasting the developmental progressions for the antecedents to emotion, physiological reactivity to emotion, emotional regulation capacity, and motivation to experience particular affective states reveals complex trajectories that intersect in a unique way during adolescence. We consider the implications of these intersecting trajectories for negative outcomes such as psychopathology, as well as positive outcomes for adolescent social bonds. PMID:26869841

Culture and the Trajectories of Developmental Pathology: Insights from Control and Information Theories.

PubMed

Wallace, Rodrick

2018-06-01

Cognition in living entities-and their social groupings or institutional artifacts-is necessarily as complicated as their embedding environments, which, for humans, includes a particularly rich cultural milieu. The asymptotic limit theorems of information and control theories permit construction of a new class of empirical 'regression-like' statistical models for cognitive developmental processes, their dynamics, and modes of dysfunction. Such models may, as have their simpler analogs, prove useful in the study and re-mediation of cognitive failure at and across the scales and levels of organization that constitute and drive the phenomena of life. These new models particularly focus on the roles of sociocultural environment and stress, in a large sense, as both trigger for the failure of the regulation of bio-cognition and as 'riverbanks' determining the channels of pathology, with implications across life-course developmental trajectories. We examine the effects of an embedding cultural milieu and its socioeconomic implementations using the 'lenses' of metabolic optimization, control system theory, and an extension of symmetry-breaking appropriate to information systems. A central implication is that most, if not all, human developmental disorders are fundamentally culture-bound syndromes. This has deep implications for both individual treatment and public health policy.

Optimal trajectories for the aeroassisted flight experiment, 1988-89

NASA Technical Reports Server (NTRS)

Miele, A.

1989-01-01

Research is summarized on optimal trajectories for the aeroassisted flight experiment, performed by the Aero-Astronautics Group of Rice University during the period 1988 through 1989. This research includes the following topics: (1) equations of motion in an Earth-fixed system; (2) equations of motion in an inertial system; (3) formultion of the optimal trajectory problem; (4) results on the optimal trajectory problem; and (5) guidance implications.

Spatial orientation perception and reflexive eye movements--a perspective, an overview, and some clinical implications

NASA Technical Reports Server (NTRS)

Guedry, F. E.; Paloski, W. F. (Principal Investigator)

1996-01-01

When head motion includes a linear velocity component, eye velocity required to track an earth-fixed target depends upon: a) angular and linear head velocity, b) target distance, and c) direction of gaze relative to the motion trajectory. Recent research indicates that eye movements (LVOR), presumably otolith-mediated, partially compensate for linear velocity in small head excursions on small devices. Canal-mediated eye velocity (AVOR), otolith-mediated eye velocity (LVOR), and Ocular Torsion (OT) can be measured, one by one, on small devices. However, response dynamics that depend upon the ratio of linear to angular velocity in the motion trajectory and on subject orientation relative to the trajectory are present in a centrifuge paradigm. With this paradigm, two 3-min runs yields measures of: LVOR differentially modulated by different subject orientations in the two runs; OT dynamics in four conditions; two directions of "steady-state" OT, and two directions of AVOR. Efficient assessment of the dynamics (and of the underlying central integrative processes) may require a centrifuge radius of 1.0 meters or more. Clinical assessment of the spatial orientation system should include evaluation of central integrative processes that determine the dynamics of these responses.

Cellular dynamical mechanisms for encoding the time and place of events along spatiotemporal trajectories in episodic memory.

PubMed

Hasselmo, Michael E; Giocomo, Lisa M; Brandon, Mark P; Yoshida, Motoharu

2010-12-31

Understanding the mechanisms of episodic memory requires linking behavioral data and lesion effects to data on the dynamics of cellular membrane potentials and population interactions within brain regions. Linking behavior to specific membrane channels and neurochemicals has implications for therapeutic applications. Lesions of the hippocampus, entorhinal cortex and subcortical nuclei impair episodic memory function in humans and animals, and unit recording data from these regions in behaving animals indicate episodic memory processes. Intracellular recording in these regions demonstrates specific cellular properties including resonance, membrane potential oscillations and bistable persistent spiking that could underlie the encoding and retrieval of episodic trajectories. A model presented here shows how intrinsic dynamical properties of neurons could mediate the encoding of episodic memories as complex spatiotemporal trajectories. The dynamics of neurons allow encoding and retrieval of unique episodic trajectories in multiple continuous dimensions including temporal intervals, personal location, the spatial coordinates and sensory features of perceived objects and generated actions, and associations between these elements. The model also addresses how cellular dynamics could underlie unit firing data suggesting mechanisms for coding continuous dimensions of space, time, sensation and action. Copyright © 2010 Elsevier B.V. All rights reserved.

Cellular dynamical mechanisms for encoding the time and place of events along spatiotemporal trajectories in episodic memory

PubMed Central

Hasselmo, Michael E.; Giocomo, Lisa M.; Yoshida, Motoharu

2010-01-01

Understanding the mechanisms of episodic memory requires linking behavioural data and lesion effects to data on the dynamics of cellular membrane potentials and population interactions within these brain regions. Linking behavior to specific membrane channels and neurochemicals has implications for therapeutic applications. Lesions of the hippocampus, entorhinal cortex and subcortical nuclei impair episodic memory function in humans and animals, and unit recording data from these regions in behaving animals indicate episodic memory processes. Intracellular recording in these regions demonstrates specific cellular properties including resonance, membrane potential oscillations and bistable persistent spiking that could underlie the encoding and retrieval of episodic trajectories. A model presented here shows how intrinsic dynamical properties of neurons could mediate the encoding of episodic memories as complex spatiotemporal trajectories. The dynamics of neurons allow encoding and retrieval of unique episodic trajectories in multiple continuous dimensions including temporal intervals, personal location, the spatial coordinates and sensory features of perceived objects and generated actions, and associations between these elements. The model also addresses how cellular dynamics could underlie unit firing data suggesting mechanisms for coding continuous dimensions of space, time, sensation and action. PMID:20018213

Grasping trajectories in a virtual environment adhere to Weber's law.

PubMed

Ozana, Aviad; Berman, Sigal; Ganel, Tzvi

2018-06-01

Virtual-reality and telerobotic devices simulate local motor control of virtual objects within computerized environments. Here, we explored grasping kinematics within a virtual environment and tested whether, as in normal 3D grasping, trajectories in the virtual environment are performed analytically, violating Weber's law with respect to object's size. Participants were asked to grasp a series of 2D objects using a haptic system, which projected their movements to a virtual space presented on a computer screen. The apparatus also provided object-specific haptic information upon "touching" the edges of the virtual targets. The results showed that grasping movements performed within the virtual environment did not produce the typical analytical trajectory pattern obtained during 3D grasping. Unlike as in 3D grasping, grasping trajectories in the virtual environment adhered to Weber's law, which indicates relative resolution in size processing. In addition, the trajectory patterns differed from typical trajectories obtained during 3D grasping, with longer times to complete the movement, and with maximum grip apertures appearing relatively early in the movement. The results suggest that grasping movements within a virtual environment could differ from those performed in real space, and are subjected to irrelevant effects of perceptual information. Such atypical pattern of visuomotor control may be mediated by the lack of complete transparency between the interface and the virtual environment in terms of the provided visual and haptic feedback. Possible implications of the findings to movement control within robotic and virtual environments are further discussed.

The power of presence: the role of mindfulness at work for daily levels and change trajectories of psychological detachment and sleep quality.

PubMed

Hülsheger, Ute R; Lang, Jonas W B; Depenbrock, Franziska; Fehrmann, Carmen; Zijlstra, Fred R H; Alberts, Hugo J E M

2014-11-01

In this research, we examined the role of mindfulness for recovery from work using a daily diary design (N = 121; 5 days; 3 measurement occasions per day). The first goal of the study was to investigate the relationship of mindfulness with sleep quality and the mediating role of psychological detachment from a day-level perspective. A second goal was to extend the process perspective in recovery research beyond the day level and consider systematic change trajectories in recovery variables over the course of the work week and the role of mindfulness in these trajectories. Results regarding day-level relationships confirmed that mindfulness experienced during work was related to subsequent sleep quality, and this relationship was mediated by psychological detachment from work in the evening. Furthermore, an investigation of the role of mindfulness in recovery change trajectories supported the idea that psychological detachment trajectories increase over the work week for individuals low on mindfulness while there was no systematic mean-level change for individuals high on mindfulness. In contrast, sleep quality followed a linear increase from Monday to Friday for all individuals, irrespective of their levels of trait mindfulness. Practical and theoretical implications for the mindfulness and the recovery literature are discussed in conclusion. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Minority Stress across the Career-Lifespan Trajectory

ERIC Educational Resources Information Center

Dispenza, Franco; Brown, Colton; Chastain, Taylor E.

2016-01-01

Sexual minority persons (e.g., lesbian, gay, bisexual, and queer) are likely to encounter "minority stress", such as discrimination, concealment, expectation of rejection, and internalized heterosexism. Minority stress occurs alongside one's lifespan and has considerable implications in the context of the career lifespan trajectory.…

Developmental Trajectories of Anxiety Symptoms Among Boys Across Early and Middle Childhood

PubMed Central

Feng, Xin; Shaw, Daniel S.; Silk, Jennifer S.

2009-01-01

This study examined the developmental trajectory of anxiety symptoms among 290 boys and evaluated the association of trajectory groups with child and family risk factors and children’s internalizing disorders. Anxiety symptoms were measured using maternal reports from the Child Behavior Checklist (T. M. Achenbach, 1991, 1992) for boys between the ages of 2 and 10. A group-based trajectory analysis revealed 4 distinct trajectories in the development of anxiety symptoms: low, low increasing, high declining, and high-increasing trajectories. Child shy temperament tended to differentiate between initial high and low groups, whereas maternal negative control and maternal depression were associated with increasing trajectories and elevated anxiety symptoms in middle childhood. Follow-up analyses to diagnoses of preadolescent depression and/or anxiety disorders revealed different patterns on the basis of trajectory group membership. The results are discussed in terms of the mechanisms of risk factors and implications for early identification and prevention. PMID:18266484

Reproductive and relational trajectories leading to pregnancy: Differences between adolescents and adult women who had an abortion.

PubMed

Pereira, Joana I F; Pires, Raquel S A; Araújo-Pedrosa, Anabela F; Canavarro, Maria Cristina C S P

2018-05-01

The literature has been conceptualizing pregnancy occurrence as a multiphase event. However, the different combinations of decisions and behaviors leading to pregnancy that end in abortion remain unexplored in the literature. The aims of the study were to describe the reproductive and relational trajectories leading to pregnancy in women who decide to abort and to explore the differences in this process according to women's age [adolescents (<20 years old) vs. adults]. In this cross-sectional study, 426 women [246 adolescents (58.4%), 177 adults (41.6%)] who chose abortion were recruited. Data on reproductive and relational characteristics were collected through a self-report questionnaire at 16 healthcare services that provide abortion. The variables were introduced in trajectories according to the criterion of temporal sequence between them: age at first sexual intercourse, relationship type, pregnancy planning, use of contraception, identification of contraceptive failure, and occurrence of pregnancy. Seven trajectories leading to pregnancy were identified. The most frequent trajectory (30.8%) included women who 1) were involved in a long-term romantic relationship, 2) did not plan the pregnancy, 3) were using contraception, and 4) did not identify the contraceptive failure that led to pregnancy. Although this was the most frequent trajectory for both age groups, the remaining trajectories showed a different distribution. Compared to adolescents, adult women's trajectories more frequently included casual relationships with non-use of contraception, or contraceptive use with no contraceptive failure identification. Our study highlights the need to recognize the multiplicity of reproductive and relational trajectories leading to pregnancies that end in abortion and their specificities according to women's age. These findings have important implications for abortion counselling and for the development of age-appropriate guidelines for preventive interventions, by drawing attention to prioritization of different contexts of intervention according women's age. Copyright © 2018 Elsevier B.V. All rights reserved.

The only girl in the room: how paradigmatic trajectories deter female students from surgical careers.

PubMed

Hill, Elspeth; Vaughan, Suzanne

2013-06-01

Over 60% of UK medical students are female, yet only 33% of applicants to surgical training are women. Role modelling, differing educational experiences and disidentification in female medical students have been implicated in this disparity. We are yet to fully understand the mechanisms that link students' experiences with national trends in career choices. We employ a hitherto unused concept from the theory of communities of practice: paradigmatic trajectories. These are visible career paths provided by a community and are cited by Wenger as potentially the most influential factors shaping the learning of newcomers. We pioneer the use of this theoretical tool in answering the research question: How do paradigmatic trajectories shape female medical students' experiences of surgery and subsequent career intentions? This qualitative study comprised a secondary analysis of data sourced from 19 clinical medical students. During individual, in-depth, semi-structured interviews, we explored these students' experiences at medical school. We carried out thematic analysis using sensitising concepts from communities of practice theory, notably that of 'paradigmatic trajectories'. Female students' experiences of surgery were strongly gendered; they were positioned as 'other' in the surgical domain. Four key processes--seeing, hearing, doing and imagining--facilitated the formation of paradigmatic trajectories, on which students could draw when making career decisions. Female students were unable to see or identify with other women in surgery. They heard about challenges to being a female surgeon, lacked experiences of participation, and struggled to imagine a future in which they would be successful surgeons. Thus, based on paradigmatic trajectories constructed from exposure to surgery, they self-selected out of surgical careers. By contrast, male students had experiences of 'hands-in' participation and were not marginalised by paradigmatic trajectories. The concept of the paradigmatic trajectory is a useful theoretical tool with which to understand how students' experiences shape career decisions. Paradigmatic trajectories within surgery deter female students from embarking on careers in surgery. © 2013 John Wiley & Sons Ltd.

Mariner-Venus-Mercury optical navigation demonstration - Results and implications for future missions

NASA Technical Reports Server (NTRS)

Acton, C. H., Jr.; Ohtakay, H.

1975-01-01

Optical navigation uses spacecraft television pictures of a target body against a known star background in a process which relates the spacecraft trajectory to the target body. This technology was used in the Mariner-Venus-Mercury mission, with the optical data processed in near-real-time, simulating a mission critical environment. Optical data error sources were identified, and a star location error analysis was carried out. Several methods for selecting limb crossing coordinates were used, and a limb smear compensation was introduced. Omission of planetary aberration corrections was the source of large optical residuals.

Identity processes and personality traits and types in adolescence: directionality of effects and developmental trajectories.

PubMed

Luyckx, Koen; Teppers, Eveline; Klimstra, Theo A; Rassart, Jessica

2014-08-01

Personality traits are hypothesized to be among the most important factors contributing to individual differences in identity development. However, longitudinal studies linking Big Five personality traits to contemporary identity models (in which multiple exploration and commitment processes are distinguished) are largely lacking. To gain more insight in the directionality of effect and the developmental interdependence of the Big Five and identity processes as forwarded in multilayered personality models, the present study assessed personality and identity in 1,037 adolescents 4 times over a period of 3 years. First, using cross-lagged path analysis, Big Five traits emerged as consistent predictors of identity exploration processes, whereas only one significant path from identity exploration to the Big Five was found. Second, using latent class growth analysis, 3 Big Five trajectory classes were identified, resembling the distinctions typically made between resilients, overcontrollers, and undercontrollers. These classes were characterized by different initial levels and (to a lesser extent) rates of change in commitment and exploration processes. In sum, important developmental associations linking personality traits to identity processes were uncovered, emphasizing the potential role of personality traits in identity development. Developmental implications and suggestions for future research are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Prevention effects on trajectories of African American adolescents' exposure to interparental conflict and depressive symptoms.

PubMed

Barton, Allen W; Beach, Steven R H; Kogan, Steven M; Stanley, Scott M; Fincham, Frank D; Hurt, Tera R; Brody, Gene H

2015-04-01

The present study investigates the trajectory of children's exposure to interparental conflict during adolescence, its effects on adolescents' psychological adjustment, as well as the ability of a family-centered prevention program to alter this trajectory. A total of 331 African American couples with an adolescent or preadolescent child participated in a randomized control trial of the Promoting Strong African American Families program, a newly developed program targeting couple and cocaregiving processes. Using a multi-informant, latent growth curve approach, child exposure to interparental conflict during adolescence was found to be stable over a period of 2 years among families in the control group, but significantly declined among families in the treatment condition. Rates of change were significantly different between intervention and control groups based on parents' report of youth exposure to interparental conflict, but not for child's report. Structural equation models found trajectory parameters of interparental conflict predicted changes in adolescent depressive symptoms, with increasing rates of changes in conflict associated with increases in adolescent internalizing symptoms over the 2-year duration of the study. Finally, a significant indirect effect was identified linking treatment, changes in parents' reports of child exposure to interparental conflict, and adolescent depressive symptoms. The implications for research and intervention are discussed. (c) 2015 APA, all rights reserved).

Prevention effects on trajectories of African American adolescents' exposure to interparental conflict and depressive symptoms

PubMed Central

Barton, Allen W.; Beach, Steven R. H.; Kogan, Steven M.; Stanley, Scott M.; Fincham, Frank D.; Hurt, Tera R.; Brody, Gene H.

2015-01-01

The present study investigates the trajectory of children's exposure to interparental conflict during adolescence, its effects on adolescents' psychological adjustment, as well as the ability of a family-centered prevention program to alter this trajectory. A total of 331 African American couples with an adolescent or pre-adolescent child participated in a randomized control trial of the Promoting Strong African American Families (ProSAAF) program, a newly-developed program targeting couple and co-caregiving processes. Using a multi-informant, latent growth curve approach, child exposure to interparental conflict during adolescence was found to be stable over a period of two years among families in the control group, but significantly declined among families in the treatment condition. Rates of change were significantly different between intervention and control groups based on parents' report of youth exposure to interparental conflict, but not for child's report. Structural equation models found trajectory parameters of interparental conflict predicted changes in adolescent depressive symptoms, with increasing rates of changes in conflict associated with increases in adolescent internalizing symptoms over the 2-year duration of the study. Finally, a significant indirect effect was identified linking treatment, changes in parents' reports of child exposure to interparental conflict, and adolescent depressive symptoms. The implications for research and intervention are discussed. PMID:25844492

Development of children's identity and position processing for letter, digit, and symbol strings: A cross-sectional study of the primary school years.

PubMed

Schubert, Teresa; Badcock, Nicholas; Kohnen, Saskia

2017-10-01

Letter recognition and digit recognition are critical skills for literate adults, yet few studies have considered the development of these skills in children. We conducted a nine-alternative forced-choice (9AFC) partial report task with strings of letters and digits, with typographical symbols (e.g., $, @) as a control, to investigate the development of identity and position processing in children. This task allows for the delineation of identity processing (as overall accuracy) and position coding (as the proportion of position errors). Our participants were students in Grade 1 to Grade 6, allowing us to track the development of these abilities across the primary school years. Our data suggest that although digit processing and letter processing end up with many similarities in adult readers, the developmental trajectories for identity and position processing for the two character types differ. Symbol processing showed little developmental change in terms of identity or position accuracy. We discuss the implications of our results for theories of identity and position coding: modified receptive field, multiple-route model, and lexical tuning. Despite moderate success for some theories, considerable theoretical work is required to explain the developmental trajectories of letter processing and digit processing, which might not be as closely tied in child readers as they are in adult readers. Copyright © 2017 Elsevier Inc. All rights reserved.

Multivariate pattern dependence

PubMed Central

Saxe, Rebecca

2017-01-01

When we perform a cognitive task, multiple brain regions are engaged. Understanding how these regions interact is a fundamental step to uncover the neural bases of behavior. Most research on the interactions between brain regions has focused on the univariate responses in the regions. However, fine grained patterns of response encode important information, as shown by multivariate pattern analysis. In the present article, we introduce and apply multivariate pattern dependence (MVPD): a technique to study the statistical dependence between brain regions in humans in terms of the multivariate relations between their patterns of responses. MVPD characterizes the responses in each brain region as trajectories in region-specific multidimensional spaces, and models the multivariate relationship between these trajectories. We applied MVPD to the posterior superior temporal sulcus (pSTS) and to the fusiform face area (FFA), using a searchlight approach to reveal interactions between these seed regions and the rest of the brain. Across two different experiments, MVPD identified significant statistical dependence not detected by standard functional connectivity. Additionally, MVPD outperformed univariate connectivity in its ability to explain independent variance in the responses of individual voxels. In the end, MVPD uncovered different connectivity profiles associated with different representational subspaces of FFA: the first principal component of FFA shows differential connectivity with occipital and parietal regions implicated in the processing of low-level properties of faces, while the second and third components show differential connectivity with anterior temporal regions implicated in the processing of invariant representations of face identity. PMID:29155809

Pathways towards instability in financial networks

NASA Astrophysics Data System (ADS)

Caldarelli, Guido; Bardoscia, Marco; Caccioli, Fabio; Battiston, Stefano

There is growing consensus that processes of market integration and risk diversification may come at the price of more systemic risk. Indeed, financial institutions are interconnected in a network of contracts where distress can either be amplified or dampened. However, a mathematical understanding of instability in relation to the network topology is still lacking. In a model financial network, we show that the origin of instability resides in the presence of specific types of cyclical structures, regardless of many of the details of the distress propagation mechanism. In particular, we show the existence of trajectories in the space of graphs along which a complex network turns from stable to unstable, although at each point along the trajectory its nodes satisfy constraints that would apparently make them individually stable. In the financial context, our findings have important implications for policies aimed at increasing financial stability. We illustrate the propositions on a sample dataset for the top 50 EU listed banks between 2008 and 2013. More in general, our results shed light on previous findings on the instability of model ecosystems and are relevant for a broad class of dynamical processes on complex networks.

Recursive processes in self-affirmation: intervening to close the minority achievement gap.

PubMed

Cohen, Geoffrey L; Garcia, Julio; Purdie-Vaughns, Valerie; Apfel, Nancy; Brzustoski, Patricia

2009-04-17

A 2-year follow-up of a randomized field experiment previously reported in Science is presented. A subtle intervention to lessen minority students' psychological threat related to being negatively stereotyped in school was tested in an experiment conducted three times with three independent cohorts (N = 133, 149, and 134). The intervention, a series of brief but structured writing assignments focusing students on a self-affirming value, reduced the racial achievement gap. Over 2 years, the grade point average (GPA) of African Americans was, on average, raised by 0.24 grade points. Low-achieving African Americans were particularly benefited. Their GPA improved, on average, 0.41 points, and their rate of remediation or grade repetition was less (5% versus 18%). Additionally, treated students' self-perceptions showed long-term benefits. Findings suggest that because initial psychological states and performance determine later outcomes by providing a baseline and initial trajectory for a recursive process, apparently small but early alterations in trajectory can have long-term effects. Implications for psychological theory and educational practice are discussed.

Detecting Appropriate Trajectories of Growth in Latent Growth Models: The Performance of Information-Based Criteria

ERIC Educational Resources Information Center

Whittaker, Tiffany A.; Khojasteh, Jam

2017-01-01

Latent growth modeling (LGM) is a popular and flexible technique that may be used when data are collected across several different measurement occasions. Modeling the appropriate growth trajectory has important implications with respect to the accurate interpretation of parameter estimates of interest in a latent growth model that may impact…

[Near infrared spectroscopy based process trajectory technology and its application in monitoring and controlling of traditional Chinese medicine manufacturing process].

PubMed

Li, Wen-Long; Qu, Hai-Bin

2016-10-01

In this paper, the principle of NIRS (near infrared spectroscopy)-based process trajectory technology was introduced.The main steps of the technique include:① in-line collection of the processes spectra of different technics; ② unfolding of the 3-D process spectra;③ determination of the process trajectories and their normal limits;④ monitoring of the new batches with the established MSPC (multivariate statistical process control) models.Applications of the technology in the chemical and biological medicines were reviewed briefly. By a comprehensive introduction of our feasibility research on the monitoring of traditional Chinese medicine technical process using NIRS-based multivariate process trajectories, several important problems of the practical applications which need urgent solutions are proposed, and also the application prospect of the NIRS-based process trajectory technology is fully discussed and put forward in the end. Copyright© by the Chinese Pharmaceutical Association.

Reach Trajectories Characterize Tactile Localization for Sensorimotor Decision Making.

PubMed

Brandes, Janina; Heed, Tobias

2015-10-07

Spatial target information for movement planning appears to be coded in a gaze-centered reference frame. In touch, however, location is initially coded with reference to the skin. Therefore, the tactile spatial location must be derived by integrating skin location and posture. It has been suggested that this recoding is impaired when the limb is placed in the opposite hemispace, for example, by limb crossing. Here, human participants reached toward visual and tactile targets located at uncrossed and crossed feet in a sensorimotor decision task. We characterized stimulus recoding by analyzing the timing and spatial profile of hand reaches. For tactile targets at crossed feet, skin-based information implicates the incorrect side, and only recoded information points to the correct location. Participants initiated straight reaches and redirected the hand toward a target presented in midflight. Trajectories to visual targets were unaffected by foot crossing. In contrast, trajectories to tactile targets were redirected later with crossed than uncrossed feet. Reaches to crossed feet usually continued straight until they were directed toward the correct tactile target and were not biased toward the skin-based target location. Occasional, far deflections toward the incorrect target were most likely when this target was implicated by trial history. These results are inconsistent with the suggestion that spatial transformations in touch are impaired by limb crossing, but are consistent with tactile location being recoded rapidly and efficiently, followed by integration of skin-based and external information to specify the reach target. This process may be implemented in a bounded integrator framework. How do you touch yourself, for instance, to scratch an itch? The place you need to reach is defined by a sensation on the skin, but our bodies are flexible, so this skin location could be anywhere in 3D space. The movement toward the tactile sensation must therefore be specified by merging skin location and body posture. By investigating human hand reach trajectories toward tactile stimuli on the feet, we provide experimental evidence that this transformation process is quick and efficient, and that its output is integrated with the original skin location in a fashion consistent with bounded integrator decision-making frameworks. Copyright © 2015 the authors 0270-6474/15/3513648-11$15.00/0.

Trajectories of marital, parent-child, and sibling conflict during pediatric cancer treatment.

PubMed

Katz, Lynn Fainsilber; Fladeboe, Kaitlyn; Lavi, Iris; King, Kevin; Kawamura, Joy; Friedman, Debra; Compas, Bruce; Breiger, David; Lengua, Liliana; Gurtovenko, Kyrill; Stettler, Nicole

2018-05-28

The stress of having a child with cancer can impact the quality of relationships within the family. The current study describes the longitudinal trajectory of marital, parent-child, and sibling conflict beginning around the time of diagnosis through the first year of treatment. We examined the average level of marital, parent-child, and sibling conflict at each monthly time point in the first year of treatment; the proportion of families that fall into the distressed range of marital, parent-child, and sibling conflict at each time point; the typical trajectory of conflict during the first year of treatment and whether there are differences in trajectories across families. A total of 160 families of children newly diagnosed with cancer (Mage = 5.6 years; range = 2-18 years) participated in a short-term prospective longitudinal study. Primary caregivers provided monthly reports of marital, parent-child, and sibling conflict. Using multilevel modeling (MLM), most families showed stability in quality of family relationships, although considerable between-family variability was observed. For married couples, 25-36% of couples were in the distressed range at one time point over the first year of treatment. For married couples, more distress occurred at earlier months, particularly month 3. For parent-child and sibling dyads, the most difficult time periods were during later months. Implications for development of interventions that target at-risk family relationships are discussed. Identifying processes that predict between-family variability in trajectories of family relationships is an important next step, particularly for the marital relationship. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Developmental trajectories of marital happiness in continuously married individuals: a group-based modeling approach.

PubMed

Anderson, Jared R; Van Ryzin, Mark J; Doherty, William J

2010-10-01

Most contemporary studies of change in marital quality over time have used growth curve modeling to describe continuously declining mean curves. However, there is some evidence that different trajectories of marital quality exist for different subpopulations. Group-based trajectory modeling provides the opportunity to conduct an empirical investigation of the variance in marital quality trajectories. We applied this method to analyze data from continuously married individuals from the Marital Instability over the Life Course Study (N = 706). Instead of a single continuously declining trajectory of marital happiness, we found 5 distinct trajectories. Nearly two thirds of participants reported high and stable levels of happiness over time, and the other one third showed either a pattern of continuous low happiness, low happiness that subsequently declined, or a curvilinear pattern of high happiness, decline, and recovery. Marital problems, time spent in shared activities, and (to a lesser degree) economic hardship were able to distinguish trajectory group membership. Our results suggest that marital happiness may have multiple distinct trajectories across reasonably diverse populations. Implications for theory, research, and practice are discussed.

Shear alters motility of Escherichia coli

NASA Astrophysics Data System (ADS)

Molaei, Mehdi; Jalali, Maryam; Sheng, Jian

2013-11-01

Understanding of locomotion of microorganisms in shear flows drew a wide range of interests in microbial related topics such as biological process including pathogenic infection and biophysical interactions like biofilm formation on engineering surfaces. We employed microfluidics and digital holography microscopy to study motility of E. coli in shear flows. We controlled the shear flow in three different shear rates: 0.28 s-1, 2.8 s-1, and 28 s-1 in a straight channel with the depth of 200 μm. Magnified holograms, recorded at 15 fps with a CCD camera over more than 20 minutes, are analyzed to obtain 3D swimming trajectories and subsequently used to extract shear responses of E.coli. Thousands of 3-D bacterial trajectories are tracked. The change of bacteria swimming characteristics including swimming velocity, reorientation, and dispersion coefficient are computed directly for individual trajectory and ensemble averaged over thousands of realizations. The results show that shear suppresses the bacterial dispersions in bulk but promote dispersions near the surface contrary to those in quiescent flow condition. Ongoing analyses are focusing to quantify effect of shear rates on tumbling frequency and reorientation of cell body, and its implication in locating the hydrodynamic mechanisms for shear enhanced angular scattering. NIH, NSF, GoMRI.

Learning while (re)configuring: Business model innovation processes in established firms.

PubMed

Berends, Hans; Smits, Armand; Reymen, Isabelle; Podoynitsyna, Ksenia

2016-08-01

This study addresses the question of how established organizations develop new business models over time, using a process research approach to trace how four business model innovation trajectories unfold. With organizational learning as analytical lens, we discern two process patterns: "drifting" starts with an emphasis on experiential learning and shifts later to cognitive search; "leaping," in contrast, starts with an emphasis on cognitive search and shifts later to experiential learning. Both drifting and leaping can result in radical business model innovations, while their occurrence depends on whether a new business model takes off from an existing model and when it goes into operation. We discuss the implications of these findings for theory on business models and organizational learning.

Learning while (re)configuring: Business model innovation processes in established firms

PubMed Central

Berends, Hans; Smits, Armand; Reymen, Isabelle; Podoynitsyna, Ksenia

2016-01-01

This study addresses the question of how established organizations develop new business models over time, using a process research approach to trace how four business model innovation trajectories unfold. With organizational learning as analytical lens, we discern two process patterns: “drifting” starts with an emphasis on experiential learning and shifts later to cognitive search; “leaping,” in contrast, starts with an emphasis on cognitive search and shifts later to experiential learning. Both drifting and leaping can result in radical business model innovations, while their occurrence depends on whether a new business model takes off from an existing model and when it goes into operation. We discuss the implications of these findings for theory on business models and organizational learning. PMID:28596704

Rare behavior of growth processes via umbrella sampling of trajectories

NASA Astrophysics Data System (ADS)

Klymko, Katherine; Geissler, Phillip L.; Garrahan, Juan P.; Whitelam, Stephen

2018-03-01

We compute probability distributions of trajectory observables for reversible and irreversible growth processes. These results reveal a correspondence between reversible and irreversible processes, at particular points in parameter space, in terms of their typical and atypical trajectories. Thus key features of growth processes can be insensitive to the precise form of the rate constants used to generate them, recalling the insensitivity to microscopic details of certain equilibrium behavior. We obtained these results using a sampling method, inspired by the "s -ensemble" large-deviation formalism, that amounts to umbrella sampling in trajectory space. The method is a simple variant of existing approaches, and applies to ensembles of trajectories controlled by the total number of events. It can be used to determine large-deviation rate functions for trajectory observables in or out of equilibrium.

The extended trajectory of hippocampal development: implications for early memory development and disorder

PubMed Central

Gómez, Rebecca L.; Edgin, Jamie O.

2015-01-01

Hippocampus has an extended developmental trajectory, with refinements occurring in the trisynaptic circuit until adolescence. While structural change should suggest a protracted course in behavior, some studies find evidence of precocious hippocampal development in the first postnatal year and continuity in memory processes beyond. However, a number of memory functions, including binding and relational inference, can be cortically supported. Evidence from the animal literature suggests that tasks often associated with hippocampus (Visual Paired Comparison, binding of a visuomotor response) can be mediated by structures external to hippocampus. Thus, a complete examination of memory development will have to rule out cortex as a source of early memory competency. We propose that early memory must show properties associated with full function of the trisynaptic circuit to reflect “adult-like” memory function, mainly 1) rapid encoding of contextual details of overlapping patterns, and 2) retention of these details over sleep-dependent delays. A wealth of evidence suggests that these functions are not apparent until 18–24 months, with behavioral discontinuities reflecting shifts in the neural structures subserving memory beginning approximately at this point in development. We discuss the implications of these observations for theories of memory and for identifying and measuring memory function in populations with typical and atypical hippocampal function. PMID:26437910

Longitudinal investigation of anxiety sensitivity growth trajectories and relations with anxiety and depression symptoms in adolescence.

PubMed

Allan, Nicholas P; Felton, Julia W; Lejuez, Carl W; MacPherson, Laura; Schmidt, Norman B

2016-05-01

Anxiety sensitivity (AS), the belief that anxious arousal is harmful, is a malleable risk factor that has been implicated in anxiety and depression symptoms in adolescents. Although there is some evidence that adolescents possess distinct developmental trajectories, few studies have explored this topic. This study examined the developmental trajectory of AS in 248 adolescents (M age = 11.0 years, SD = 0.82; 56% male) across 6 years, beginning when children were age 11. This study also examined the influence of AS trajectories on anxiety and depression at age 16. Finally, this study examined the utility of AS classes in identifying anxiety and depression growth. Three AS classes were found, described by normative-stable, high-stable, and high-unstable trajectories. Adolescents in the high-stable and the high-unstable AS classes had higher levels of anxiety and depression at age 16 than did adolescents in the normative-stable AS class. In addition, the anxiety and depression trajectories fit by AS class mirrored the AS class trajectories. These findings suggest three AS trajectories can be identified in adolescents. These trajectories are discussed in relation to a developmental perspective of AS.

Ares I-X Best Estimated Trajectory Analysis and Results

NASA Technical Reports Server (NTRS)

Karlgaard, Christopher D.; Beck, Roger E.; Starr, Brett R.; Derry, Stephen D.; Brandon, Jay; Olds, Aaron D.

2011-01-01

The Ares I-X trajectory reconstruction produced best estimated trajectories of the flight test vehicle ascent through stage separation, and of the first and upper stage entries after separation. The trajectory reconstruction process combines on-board, ground-based, and atmospheric measurements to produce the trajectory estimates. The Ares I-X vehicle had a number of on-board and ground based sensors that were available, including inertial measurement units, radar, air-data, and weather balloons. However, due to problems with calibrations and/or data, not all of the sensor data were used. The trajectory estimate was generated using an Iterative Extended Kalman Filter algorithm, which is an industry standard processing algorithm for filtering and estimation applications. This paper describes the methodology and results of the trajectory reconstruction process, including flight data preprocessing and input uncertainties, trajectory estimation algorithms, output transformations, and comparisons with preflight predictions.

Ares I-X Best Estimated Trajectory and Comparison with Pre-Flight Predictions

NASA Technical Reports Server (NTRS)

Karlgaard, Christopher D.; Beck, Roger E.; Derry, Stephen D.; Brandon, Jay M.; Starr, Brett R.; Tartabini, Paul V.; Olds, Aaron D.

2011-01-01

The Ares I-X trajectory reconstruction produced best estimated trajectories of the flight test vehicle ascent through stage separation, and of the first and upper stage entries after separation. The trajectory reconstruction process combines on-board, ground-based, and atmospheric measurements to produce the trajectory estimates. The Ares I-X vehicle had a number of on-board and ground based sensors that were available, including inertial measurement units, radar, air- data, and weather balloons. However, due to problems with calibrations and/or data, not all of the sensor data were used. The trajectory estimate was generated using an Iterative Extended Kalman Filter algorithm, which is an industry standard processing algorithm for filtering and estimation applications. This paper describes the methodology and results of the trajectory reconstruction process, including flight data preprocessing and input uncertainties, trajectory estimation algorithms, output transformations, and comparisons with preflight predictions.

Semi-Automated Processing of Trajectory Simulator Output Files for Model Evaluation

DTIC Science & Technology

2018-01-01

ARL-TR-8284 ● JAN 2018 US Army Research Laboratory Semi-Automated Processing of Trajectory Simulator Output Files for Model......Do not return it to the originator. ARL-TR-8284 ● JAN 2018 US Army Research Laboratory Semi-Automated Processing of Trajectory

The role of maxillofacial radiologists in gunshot injuries: a hypothesized missile trajectory in two case reports

PubMed Central

Sansare, K; Khanna, V; Karjodkar, F

2011-01-01

Gunshot injuries are an emerging form of trauma that oral radiologists increasingly have to deal with. There are two main types of gunshot injuries: high-velocity and low-velocity bullet injuries. The outcome of high-velocity gunshot injury is usually fatal; however, a non-fatal low-velocity injury to the maxillofacial region is more likely to be encountered by the oral and maxillofacial radiologist. It is therefore important to up-to-date knowledge of ballistic science and its implications in the field of maxillofacial radiology. The ability of oral and maxillofacial radiologists to predict the missile trajectory will aid the assessment and localization of the damage caused by the bullet and its splinters. Predicting the missile trajectory may also be of help to law enforcement agencies and forensic scientists in determining the type of firearm used and direction of fire. This article, which examines two cases, attempts to highlight to the oral radiologist this emerging form of trauma and its implications. PMID:21159916

The role of maxillofacial radiologists in gunshot injuries: a hypothesized missile trajectory in two case reports.

PubMed

Sansare, K; Khanna, V; Karjodkar, F

2011-01-01

Gunshot injuries are an emerging form of trauma that oral radiologists increasingly have to deal with. There are two main types of gunshot injuries: high-velocity and low-velocity bullet injuries. The outcome of high-velocity gunshot injury is usually fatal; however, a non-fatal low-velocity injury to the maxillofacial region is more likely to be encountered by the oral and maxillofacial radiologist. It is therefore important to up-to-date knowledge of ballistic science and its implications in the field of maxillofacial radiology. The ability of oral and maxillofacial radiologists to predict the missile trajectory will aid the assessment and localization of the damage caused by the bullet and its splinters. Predicting the missile trajectory may also be of help to law enforcement agencies and forensic scientists in determining the type of firearm used and direction of fire. This article, which examines two cases, attempts to highlight to the oral radiologist this emerging form of trauma and its implications.

Trajectories of psychological distress among low-income, female survivors of Hurricane Katrina.

PubMed

Lowe, Sarah R; Rhodes, Jean E

2013-01-01

The purpose of this study was to investigate trajectories of psychological distress among low-income, primarily unmarried and African American women who survived Hurricane Katrina (N = 386). Data were collected in the year prior to the hurricane as well as approximately 1 and 3 years thereafter. Using Latent Class Growth Analysis (LCGA), we detected 6 distinct trajectory groups. Over half of the participants fit into a trajectory consistent with resilience; that is, they maintained low levels of psychological distress over the course of the study, but experienced an elevation in symptoms at the first predisaster time point followed by a return to predisaster levels. The other trajectories reflected a range of psychological responses to disasters and indicated that predisaster functioning had a major influence on postdisaster psychological outcomes. Degree of exposure to hurricane-related stressors, experiences of human and pet bereavement, perceived social support, and socioeconomic status were significant predictors of trajectory group membership. Implications for research and policy are discussed. © 2013 American Orthopsychiatric Association.

Sexual and general offending trajectories of men referred for civil commitment.

PubMed

Francis, Brian; Harris, Danielle Arlanda; Wallace, Stephanie; Knight, Raymond A; Soothill, Keith

2014-08-01

Policies aimed at managing high-risk offenders, which include sex offenders, often assume they are a homogeneous population. These policies also tend to assume the pattern of offending is the same for all sex offenders, and is stable. This study challenges these assumptions by examining the life course offending trajectories of 780 convicted adult male sexual offenders. The men were referred to the Massachusetts Treatment Center for civil commitment between 1959 and 1984. The changing number of both sexual and any offenses were examined by age using Group-Based Trajectory Modeling. We identified a four-trajectory model for all offending and a four-trajectory model for sexual offending. The identified groups varied in several offending patterns including criminal onset, length of criminal careers, age of peak offending, and time of entry into the treatment center. Late adult onset of sex offending was found to be associated with child molestation, whereas early-onset trajectories were associated with rape. Implications for future research and policy are discussed. © The Author(s) 2013.

Six years after the wave. Trajectories of posttraumatic stress following a natural disaster.

PubMed

Johannesson, Kerstin Bergh; Arinell, Hans; Arnberg, Filip K

2015-12-01

The characteristics of long-term trajectories of distress after disasters are unclear, since few studies include a comparison group. This study examines trajectories of recovery among survivors in comparison to individuals with indirect exposure. Postal surveys were sent to Swedish tourists, repatriated from the 2004 Indian Ocean tsunami (n=2268), at 1, 3, and 6 years after the tsunami to assess posttraumatic stress (PTS) and poor mental health. Items were used to ascertain high and moderate disaster exposure groups and an indirect exposure comparison group. Long-term PTS trajectories were best characterized by a resilient (72.3%), a severe chronic (4.6%), a moderate chronic (11.2%) and a recovering (11.9%) trajectory. Trajectories reported higher levels of PTS than the comparison group. Exposure severity and bereavement were highly influential risk factors. These findings have implications regarding anticipation of long-term psychological adjustment after natural disasters and need for interventions after a single traumatic event with few secondary stressors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Lunar lander stage requirements based on the Civil Needs Data Base

NASA Technical Reports Server (NTRS)

Mulqueen, John A.

1992-01-01

This paper examines the lunar lander stages that will be necessary for the future exploration and development of the Moon. Lunar lander stage sizing is discussed based on the projected lunar payloads listed in the Civil Needs Data Base. Factors that will influence the lander stage design are identified and discussed. Some of these factors are (1) lunar orbiting and lunar surface lander bases; (2) implications of direct landing trajectories and landing from a parking orbit; (3) implications of landing site and parking orbit; (4) implications of landing site and parking orbit selection; (5) the use of expendable and reusable lander stages; and (6) the descent/ascent trajectories. Data relating the lunar lander stage design requirements to each of the above factors and others are presented in parametric form. These data will provide useful design data that will be applicable to future mission model modifications and design studies.

Atypical development of configural face recognition in children with autism, Down syndrome and Williams syndrome.

PubMed

Dimitriou, D; Leonard, H C; Karmiloff-Smith, A; Johnson, M H; Thomas, M S C

2015-05-01

Configural processing in face recognition is a sensitivity to the spacing between facial features. It has been argued both that its presence represents a high level of expertise in face recognition, and also that it is a developmentally vulnerable process. We report a cross-syndrome investigation of the development of configural face recognition in school-aged children with autism, Down syndrome and Williams syndrome compared with a typically developing comparison group. Cross-sectional trajectory analyses were used to compare configural and featural face recognition utilising the 'Jane faces' task. Trajectories were constructed linking featural and configural performance either to chronological age or to different measures of mental age (receptive vocabulary, visuospatial construction), as well as the Benton face recognition task. An emergent inversion effect across age for detecting configural but not featural changes in faces was established as the marker of typical development. Children from clinical groups displayed atypical profiles that differed across all groups. We discuss the implications for the nature of face processing within the respective developmental disorders, and how the cross-sectional syndrome comparison informs the constraints that shape the typical development of face recognition. © 2014 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd.

Shifting Attendance Trajectories from Middle to High School: Influences of School Transitions and Changing School Contexts

PubMed Central

Benner, Aprile D.; Wang, Yijie

2014-01-01

In the current study, we examine patterns of school attendance across middle and high school with a diverse sample of 8,908 students (48% female; 54% Latino, 31% White, 13% African American, 2% Asian American). Attendance declined from middle through high school, but this overall pattern masked important variations. In total, 44% of students maintained their attendance trajectories from middle to high school (11% stable high, 19% high-decreasing, 10% mid-decreasing, 4% low-decreasing), and shifting attendance trajectories often signaled greater school disengagement (38% shifted to poorer attendance trajectories, 18% experienced improved attendance trajectories). Transition experiences, school structural characteristics, and the divergence between students’ middle and high schools provided insights into which students recovered, becoming more engaged in high school versus those who became more disconnected. Implications for identifying and intervening with disengaged youth are discussed. PMID:24364827

Transitions in young adulthood: Exploring trajectories of parent-child conflict during college.

PubMed

Nelson, Sarah C; Bahrassa, Nazneen F; Syed, Moin; Lee, Richard M

2015-07-01

This longitudinal study examined trajectories of parent-child conflict from the perspective of young adults during their college years. Using group-based trajectory modeling, self-report data from 3 time points were analyzed and 4 conflict trajectories emerged. The largest group of students (65%) had low, stable levels of parent-child conflict. Ten percent of the sample reported increases in parent-child conflict, and the remainder (25%) reported 1 of 2 patterns of decreasing parent-child conflict. Students with at least 1 immigrant parent were more likely to experience changes in parent-child conflict in contrast to peers with no immigrant parents. Contrary to our hypotheses, individuals in the groups in which conflict was decreasing were more likely to experience psychological distress. Results are discussed in terms of implications for the heterogeneity of conflict trajectories over time, particularly considering the contextual influence of immigrant family status. (c) 2015 APA, all rights reserved).

Behavior Problems in Elementary School among Low-Income Males: The Role of Teacher-Child Relationships

PubMed Central

O’Connor, Erin Eileen; Supplee, Lauren

2017-01-01

The present study identified trajectories of teacher-child relationship conflict and closeness from first through sixth grades, and associations between these trajectories and externalizing and internalizing behaviors at age 11 among low-income, urban males (N = 262). There were three main findings. Nagin cluster analyses indicated five trajectories for conflict with all children evidencing increases in conflict, and four trajectories for closeness with all children demonstrating decreases in closeness. Trajectories with higher levels of conflict and lower levels of closeness were associated with higher levels of externalizing and internalizing behavior problems at age 11. Moreover, conflictual teacher-child relationships exacerbated the effects of externalizing and internalizing behavior problems in early childhood; children with conflictual teacher-child relationships had higher levels of behavior problems in middle childhood relative to children with low conflictual teacher-child relationships. Implications of targeting teacher-child relationships as interventions to help prevent behavior problems are discussed. PMID:29170565

Anti-aging science: The emergence, maintenance, and enhancement of a discipline

PubMed Central

Fishman, Jennifer R.; Binstock, Robert H.; Lambrix, Marcie A.

2012-01-01

Through archival analysis this article traces the emergence, maintenance, and enhancement of biogerontology as a scientific discipline in the United States. At first, biogerontologists' attempts to control human aging were regarded as a questionable pursuit due to: perceptions that their efforts were associated with the long history of charlatanic, anti-aging medical practices; the idea that anti-aging is a “forbidden science” ethically and scientifically; and the perception that the field was scientifically bereft of rigor and scientific innovation. The hard-fought establishment of the National Institute on Aging, scientific advancements in genetics and biotechnology, and consistent “boundary work” by scientists, have allowed biogerontology to flourish and gain substantial legitimacy with other scientists and funding agencies, and in the public imagination. In particular, research on genetics and aging has enhanced the stature and promise of the discipline by setting it on a research trajectory in which explanations of the aging process, rather than mere descriptions, have become a central focus. Moreover, if biogerontologists' efforts to control the processes of human aging are successful, this trajectory has profound implications for how we conceive of aging, and for the future of many of our social institutions. PMID:23264719

Becoming a Physicist: How Identities and Practices Shape Physics Trajectories

NASA Astrophysics Data System (ADS)

Quan, Gina M.

This dissertation studies the relationships and processes which shape students' participation within the discipline of physics. Studying this early disciplinary participation gives insight to how students are supported in or pushed out of physics, which is an important step in cultivating a diverse set of physics students. This research occurs within two learning environments that we co-developed: a physics camp for high school girls and a seminar for undergraduate physics majors to get started in physics research. Using situated learning theory, we conceptualized physics learning to be intertwined with participation in physics practices and identity development. This theoretical perspective draws our attention to relationships between students and the physics community. Specifically, we study how students come to engage in the practices of the community and who they are within the physics community. We find that students' interactions with faculty and peers impact the extent to which students engage in authentic physics practices. These interactions also impact the extent to which students develop identities as physicists. We present implications of these findings for the design of physics learning spaces. Understanding this process of how students become members of the physics community will provide valuable insights into fostering a diverse set of successful trajectories in physics.

A cross-syndrome study of the development of holistic face recognition in children with autism, Down syndrome, and Williams syndrome.

PubMed

Annaz, Dagmara; Karmiloff-Smith, Annette; Johnson, Mark H; Thomas, Michael S C

2009-04-01

We report a cross-syndrome comparison of the development of holistic processing in face recognition in school-aged children with developmental disorders: autism, Down syndrome, and Williams syndrome. The autism group was split into two groups: one with high-functioning children and one with low-functioning children. The latter group has rarely been studied in this context. The four disorder groups were compared with typically developing children. Cross-sectional trajectory analyses were used to compare development in a modified version of Tanaka and Farah's part-whole task. Trajectories were constructed linking part-whole performance either to chronological age or to several measures of mental age (receptive vocabulary, visuospatial construction, and the Benton Facial Recognition Test). In addition to variable delays in onset and rate of development, we found an atypical profile in all disorder groups. These profiles were atypical in different ways, indicating multiple pathways to, and variable outcomes in, the development of face recognition. We discuss the implications for theories of face recognition in both atypical and typical development, including the idea that part-whole and rotation manipulations may tap different aspects of holistic and/or configural processing.

Joint trajectories of depression and perfectionism across adolescence and childhood risk factors.

PubMed

Vaillancourt, Tracy; Haltigan, John D

2018-05-01

The codevelopment of symptoms of depression and socially prescribed perfectionism across adolescence (age 12-17) and non-age-overlapping childhood predictors (age 10-11) of joint trajectory group membership were examined in a sample of 700 Canadian youth. Results indicated that most adolescents (75.8%) followed a trajectory of low depression symptoms (low stable), whereas 15.7% followed an increasing trajectory (increasing), and 8.5% followed a trajectory that began high and decreased over time (high decreasing). More girls than boys were found in the increasing and high decreasing depression trajectories. Adolescents followed three distinct trajectories of socially prescribed perfectionism: 41.6% were in a low stable group, 40.5% in a moderate increasing group, and 17.9% in a high increasing group. Eight percent followed a high-risk dual trajectory of increasing depression and high increasing socially prescribed perfectionism. This joint trajectory was predicted by being bullied, anxious, and relationally aggressive (compared to the low-risk trajectory of low stable depression and perfectionism) at ages 10 and 11. These same predictors, along with poorer family functioning and lower family income, differentiated the joint high decreasing depression/high increasing perfectionism group from the low/low joint group, which comprised of 3.8% of the sample. The developmental progression was best characterized as depression leading to socially prescribed perfectionism. Implications for clinical practice are discussed.

Risk and panic in late modernity: implications of the converging sites of social anxiety.

PubMed

Hier, Sean P

2003-03-01

Comparing moral panic with the potential catastrophes of the risk society, Sheldon Ungar contends that new sites of social anxiety emerging around nuclear, medical, environmental and chemical threats have thrown into relief many of the questions motivating moral panic research agendas. He argues that shifting sites of social anxiety necessitate a rethinking of theoretical, methodological and conceptual issues related to processes of social control, claims making and general perceptions of public safety. This paper charts an alternative trajectory, asserting that analytic priority rests not with an understanding of the implications of changing but converging sites of social anxiety. Concentrating on the converging sites of social anxiety in late modernity, the analysis forecasts a proliferation of moral panics as an exaggerated symptom of the heightened sense of uncertainty purported to accompany the ascendency of the risk society.

The Trajectory of Coparenting Satisfaction in African American Families: The Impact of Sociocultural Stressors and Supports

PubMed Central

Riina, Elizabeth M.; McHale, Susan M.

2013-01-01

Based in family systems and ecological perspectives, this study expands the scope of coparenting research by: (a) charting the trajectory of coparenting satisfaction for mothers and fathers in two-parent African American families during their offspring's adolescence, and (b) examining the role of sociocultural stressors and supports for coparenting satisfaction. Participants were 192 African American mothers and fathers who reported on their coparenting satisfaction and both economic and cultural stressors (economic strain and racial discrimination), and supports (socioeconomic resources and religiosity). Longitudinal growth curves revealed declines in coparenting satisfaction for fathers but not mothers over the course of offspring's adolescence. Findings were generally consistent with hypotheses that stressors were negatively, and supports, positively, related to average levels of coparenting satisfaction. Findings for racial discrimination and income differed by parent and highlighted gender dynamics within couple relationships. We discuss implications for understanding of normative family processes in African American families as these unfold within both family and broader sociocultural contexts. PMID:23066677

First-Grade Predictors of Mathematical Learning Disability: A Latent Class Trajectory Analysis

PubMed Central

Geary, David C.; Bailey, Drew H.; Littlefield, Andrew; Wood, Phillip; Hoard, Mary K.; Nugent, Lara

2009-01-01

Kindergarten to 3rd grade mathematics achievement scores from a prospective study of mathematical development were subjected to latent growth trajectory analyses (n = 306). The four corresponding classes included children with mathematical learning disability (MLD, 6% of sample), and low (LA, 50%), typically (TA, 39%) and high (HA, 5%) achieving children. The groups were administered a battery of intelligence (IQ), working memory, and mathematical-cognition measures in 1st grade. The children with MLD had general deficits in working memory and IQ, and potentially more specific deficits on measures of number sense. The LA children did not have working memory or IQ deficits, but showed moderate deficits on these number sense measures and for addition fact retrieval. The distinguishing features of the HA children were a strong visuospatial working memory, a strong number sense, and frequent use of memory-based processes to solve addition problems. Implications for the early identification of children at risk for poor mathematics achievement are discussed. PMID:20046817

Multiple transitions and HIV risk among orphaned Kenyan schoolgirls.

PubMed

Mojola, Sanyu A

2011-03-01

Why are orphaned girls at particular risk of acquiring HIV infection? Using a transition-to-adulthood framework, this study employs qualitative data from Nyanza Province, Kenya, to explore pathways to HIV risk among orphaned and nonorphaned high-school girls. It shows how simultaneous processes such as leaving their parental home, negotiating financial access, and relationship transitions interact to produce disproportionate risk for orphaned girls. The role of financial provision and parental love in modifying girls' trajectories to risk are also explored. A testable theoretical model is proposed based on the qualitative findings, and policy implications are suggested.

MULTIPLE TRANSITIONS AND HIV RISK AMONG AFRICAN SCHOOL GIRLS

PubMed Central

Mojola, Sanyu A

2012-01-01

Why are orphaned girls at particular risk of contracting HIV? Using a transition to adulthood framework, this paper uses qualitative data from Nyanza province, Kenya to explore pathways to HIV risk among orphaned and non-orphaned high school girls. I show how co-occurring processes such as residential transition out of the parental home, negotiating financial access and relationship transitions interact to produce disproportionate risk for orphan girls. I also explore the role of financial provision and parental love in modifying girls’ trajectories to risk. I propose a testable theoretical model based on the qualitative findings and suggest policy implications. PMID:21500699

Classification of Dynamical Diffusion States in Single Molecule Tracking Microscopy

PubMed Central

Bosch, Peter J.; Kanger, Johannes S.; Subramaniam, Vinod

2014-01-01

Single molecule tracking of membrane proteins by fluorescence microscopy is a promising method to investigate dynamic processes in live cells. Translating the trajectories of proteins to biological implications, such as protein interactions, requires the classification of protein motion within the trajectories. Spatial information of protein motion may reveal where the protein interacts with cellular structures, because binding of proteins to such structures often alters their diffusion speed. For dynamic diffusion systems, we provide an analytical framework to determine in which diffusion state a molecule is residing during the course of its trajectory. We compare different methods for the quantification of motion to utilize this framework for the classification of two diffusion states (two populations with different diffusion speed). We found that a gyration quantification method and a Bayesian statistics-based method are the most accurate in diffusion-state classification for realistic experimentally obtained datasets, of which the gyration method is much less computationally demanding. After classification of the diffusion, the lifetime of the states can be determined, and images of the diffusion states can be reconstructed at high resolution. Simulations validate these applications. We apply the classification and its applications to experimental data to demonstrate the potential of this approach to obtain further insights into the dynamics of cell membrane proteins. PMID:25099798

Human-Centered Systems Analysis of Aircraft Separation from Adverse Weather: Implications for Icing Remote Sensing

NASA Technical Reports Server (NTRS)

Vigeant-Langlois, Laurence; Hansman, R. John, Jr.

2003-01-01

The objective of this project was to propose a means to improve aviation weather information, training procedures based on a human-centered systems approach. Methodology: cognitive analysis of pilot's tasks; trajectory-based approach to weather information; contingency planning support; and implications for improving weather information.

Development of the Adolescent Brain: Implications for Executive Function and Social Cognition

ERIC Educational Resources Information Center

Blakemore, Sarah-Jayne; Choudhury, Suparna

2006-01-01

Adolescence is a time of considerable development at the level of behaviour, cognition and the brain. This article reviews histological and brain imaging studies that have demonstrated specific changes in neural architecture during puberty and adolescence, outlining trajectories of grey and white matter development. The implications of brain…

Strengthening the Superintendent Pipeline and Professional Development Options. Implications from UCEA

ERIC Educational Resources Information Center

McCord, Bob

2009-01-01

The dramatic change over the past 20 years of the demographics, education and career trajectory of superintendents has significant implications for the nation's schools. Since 1923, the State of the American School Superintendency has documented the evolution of superintendents' careers and school district leadership more broadly. The most recent…

Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings

PubMed Central

Tomlinson, Samuel B.; Bermudez, Camilo; Conley, Chiara; Brown, Merritt W.; Porter, Brenda E.; Marsh, Eric D.

2016-01-01

Synchronized cortical activity is implicated in both normative cognitive functioning and many neurologic disorders. For epilepsy patients with intractable seizures, irregular synchronization within the epileptogenic zone (EZ) is believed to provide the network substrate through which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical for detecting seizure networks in order to achieve postsurgical seizure control. However, automated techniques for characterizing epileptic networks have yet to gain traction in the clinical setting. Recent advances in signal processing and spike detection have made it possible to examine the spatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, we present a novel methodology for detecting, extracting, and visualizing spike propagation and demonstrate its potential utility as a biomarker for the EZ. Eighteen presurgical intracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable (i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novel algorithms were applied to extract multichannel spike discharges and visualize their spatiotemporal propagation. Quantitative analysis of spike propagation was performed using trajectory clustering and spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed an increase in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared with Sz-Persist patients. The pathophysiological basis and clinical implications of these findings are considered. PMID:28066315

The extended trajectory of hippocampal development: Implications for early memory development and disorder.

PubMed

Gómez, Rebecca L; Edgin, Jamie O

2016-04-01

Hippocampus has an extended developmental trajectory, with refinements occurring in the trisynaptic circuit until adolescence. While structural change should suggest a protracted course in behavior, some studies find evidence of precocious hippocampal development in the first postnatal year and continuity in memory processes beyond. However, a number of memory functions, including binding and relational inference, can be cortically supported. Evidence from the animal literature suggests that tasks often associated with hippocampus (visual paired comparison, binding of a visuomotor response) can be mediated by structures external to hippocampus. Thus, a complete examination of memory development will have to rule out cortex as a source of early memory competency. We propose that early memory must show properties associated with full function of the trisynaptic circuit to reflect "adult-like" memory function, mainly (1) rapid encoding of contextual details of overlapping patterns, and (2) retention of these details over sleep-dependent delays. A wealth of evidence suggests that these functions are not apparent until 18-24 months, with behavioral discontinuities reflecting shifts in the neural structures subserving memory beginning approximately at this point in development. We discuss the implications of these observations for theories of memory and for identifying and measuring memory function in populations with typical and atypical hippocampal function. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

An Optimized Trajectory Planning for Welding Robot

NASA Astrophysics Data System (ADS)

Chen, Zhilong; Wang, Jun; Li, Shuting; Ren, Jun; Wang, Quan; Cheng, Qunchao; Li, Wentao

2018-03-01

In order to improve the welding efficiency and quality, this paper studies the combined planning between welding parameters and space trajectory for welding robot and proposes a trajectory planning method with high real-time performance, strong controllability and small welding error. By adding the virtual joint at the end-effector, the appropriate virtual joint model is established and the welding process parameters are represented by the virtual joint variables. The trajectory planning is carried out in the robot joint space, which makes the control of the welding process parameters more intuitive and convenient. By using the virtual joint model combined with the B-spline curve affine invariant, the welding process parameters are indirectly controlled by controlling the motion curve of the real joint. To solve the optimal time solution as the goal, the welding process parameters and joint space trajectory joint planning are optimized.

Trajectories of Parenting Processes and Adolescent Substance Use: Reciprocal Effects

ERIC Educational Resources Information Center

Coley, Rebekah Levine; Votruba-Drzal, Elizabeth; Schindler, Holly S.

2008-01-01

Drawing on transactional theories of child development, we assessed bidirectional links between trajectories of adolescent substance use and parenting processes from early through mid adolescence. Hierarchical generalized models estimated trajectories for 3,317 adolescents from the National Longitudinal Survey of Youth 1997, exploring both…

The role of parental alcohol use, parental discipline and antisocial behaviour on adolescent drinking trajectories.

PubMed

Alati, R; Baker, P; Betts, K S; Connor, J P; Little, K; Sanson, A; Olsson, C A

2014-01-01

Parental drinking, harsh parental discipline and adolescent antisocial behaviour have been independently implicated in adolescent alcohol use. Robust prospective studies are required to examine developmental relationships between these factors and their effect on trajectories of alcohol use across adolescence. Data were ascertained at three consecutive adolescent waves (13.5, 15.5 and 17.5 years) from the Australian Temperament Project, a 15-wave (30 year) general population birth cohort in Victoria, Australia. Adolescent alcohol trajectories, adjusted for time-varying measures of parenting and antisocial behaviour, were regressed on time-stable measures of parental alcohol use. The full case analysis comprised 751 individuals with complete data. Two distinct alcohol trajectories were identified across the three adolescent waves after adjusting for time-varying factors: a higher and lower drinking group. Both trajectories increased linearly over the study period. Antisocial behaviour was positively associated with both trajectories while harsh parental discipline was positively associated with alcohol use in the lower-use group only. Increased maternal and paternal drinking at 13.5 years placed teenagers at a greater risk of being included in the high-risk trajectory. Parental drinking was the strongest predictor of different drinking trajectories in adolescence. This finding underscores the importance of comprehensive public heath approaches that target both parental and adolescent drinking attitudes and behaviour.

Structural neuroimaging across early-stage psychosis: Aberrations in neurobiological trajectories and implications for the staging model.

PubMed

Bartholomeusz, Cali F; Cropley, Vanessa L; Wannan, Cassandra; Di Biase, Maria; McGorry, Patrick D; Pantelis, Christos

2017-05-01

This review critically examines the structural neuroimaging evidence in psychotic illness, with a focus on longitudinal imaging across the first-episode psychosis and ultra-high-risk of psychosis illness stages. A thorough search of the literature involving specifically longitudinal neuroimaging in early illness stages of psychosis was conducted. The evidence supporting abnormalities in brain morphology and altered neurodevelopmental trajectories is discussed in the context of a clinical staging model. In general, grey matter (and, to a lesser extent, white matter) declines across multiple frontal, temporal (especially superior regions), insular and parietal regions during the first episode of psychosis, which has a steeper trajectory than that of age-matched healthy counterparts. Although the ultra-high-risk of psychosis literature is considerably mixed, evidence indicates that certain volumetric structural aberrations predate psychotic illness onset (e.g. prefrontal cortex thinning), while other abnormalities present in ultra-high-risk of psychosis populations are potentially non-psychosis-specific (e.g. hippocampal volume reductions). We highlight the advantages of longitudinal designs, discuss the implications such studies have on clinical staging and provide directions for future research.

High-Speed Printing Process Characterization using the Lissajous Trajectory Method

NASA Astrophysics Data System (ADS)

Lee, Sangwon; Kim, Daekeun

2018-04-01

We present a novel stereolithographic three-dimensional (3D) printing process that uses Lissajous trajectories. By using Lissajous trajectories, this 3D printing process allows two laser-scanning mirrors to operate at similar high-speed frequencies simultaneously, and the printing speed can be faster than that of raster scanning used in conventional stereolithography. In this paper, we first propose the basic theoretical background for this printing process based on Lissajous trajectories. We also characterize its printing conditions, such as printing size, laser spot size, and minimum printing resolution, with respect to the operating frequencies of the scanning mirrors and the capability of the laser modulation. Finally, we demonstrate simulation results for printing basic 2D shapes by using a noble printing process algorithm.

MIDAS - Mission design and analysis software for the optimization of ballistic interplanetary trajectories

NASA Technical Reports Server (NTRS)

Sauer, Carl G., Jr.

1989-01-01

A patched conic trajectory optimization program MIDAS is described that was developed to investigate a wide variety of complex ballistic heliocentric transfer trajectories. MIDAS includes the capability of optimizing trajectory event times such as departure date, arrival date, and intermediate planetary flyby dates and is able to both add and delete deep space maneuvers when dictated by the optimization process. Both powered and unpowered flyby or gravity assist trajectories of intermediate bodies can be handled and capability is included to optimize trajectories having a rendezvous with an intermediate body such as for a sample return mission. Capability is included in the optimization process to constrain launch energy and launch vehicle parking orbit parameters.

On the interaction of deaffrication and consonant harmony*

PubMed Central

Dinnsen, Daniel A.; Gierut, Judith A.; Morrisette, Michele L.; Green, Christopher R.; Farris-Trimble, Ashley W.

2010-01-01

Error patterns in children’s phonological development are often described as simplifying processes that can interact with one another with different consequences. Some interactions limit the applicability of an error pattern, and others extend it to more words. Theories predict that error patterns interact to their full potential. While specific interactions have been documented for certain pairs of processes, no developmental study has shown that the range of typologically predicted interactions occurs for those processes. To determine whether this anomaly is an accidental gap or a systematic peculiarity of particular error patterns, two commonly occurring processes were considered, namely Deaffrication and Consonant Harmony. Results are reported from a cross-sectional and longitudinal study of 12 children (age 3;0 – 5;0) with functional phonological delays. Three interaction types were attested to varying degrees. The longitudinal results further instantiated the typology and revealed a characteristic trajectory of change. Implications of these findings are explored. PMID:20513256

Trajectories of Adolescent Hostile-Aggressive Behavior and Family Climate: Longitudinal Implications for Young Adult Romantic Relationship Competence

ERIC Educational Resources Information Center

Fosco, Gregory M.; Van Ryzin, Mark J.; Xia, Mengya; Feinberg, Mark E.

2016-01-01

The formation and maintenance of young adult romantic relationships that are free from violence and are characterized by love, connection, and effective problem-solving have important implications for later well-being and family functioning. In this study, we examined adolescent hostile-aggressive behavior (HAB) and family relationship quality as…

Early Influences and Later Outcomes Associated With Developmental Trajectories of Eriksonian Fidelity

PubMed Central

Brittian, Aerika S.; Lerner, Richard M.

2014-01-01

Although Eriksonian theory suggests that adolescents’ sense of fidelity is a key component of healthy development, research on this psychosocial construct has been limited. The current study developed an index of youth fidelity, examined the developmental course of this construct, explored the influence of contextual factors on different fidelity trajectories, and tested if trajectories were associated with later indicators of adolescents’ positive development. Participants included 1,941 ethnically diverse youth (61% female) participants in the 4-H Study of Positive Youth Development who were recruited from schools and youth development programs across the United States. Results suggested that three types of developmental trajectories existed among youth: high and increasing, moderate and increasing, and low and decreasing. Fidelity group membership varied in relation to social relationships and psychosocial and behavioral characteristics (i.e., contribution, substance use, and delinquency). Girls were more likely than boys to be in the highest fidelity trajectories. Directions for future research and implications for enhancing the thriving of adolescents are discussed. PMID:22545838

Trajectories of Internalizing, Externalizing, and Grades for Children Who Have and Have Not Experienced Their Parents' Divorce or Separation

PubMed Central

Lansford, Jennifer E.; Malone, Patrick S.; Castellino, Domini R.; Dodge, Kenneth A.; Pettit, Gregory S.; Bates, John E.

2009-01-01

This study examined whether the occurrence and timing of parental separation or divorce was related to trajectories of academic grades and mother- and teacher-reported internalizing and externalizing problems. The authors used hierarchical linear models to estimate trajectories for children who did and did not experience their parents' divorce or separation in kindergarten through 10th grade (N = 194). A novel approach to analyzing the timing of divorce/separation was adopted, and trajectories were estimated from 1 year prior to the divorce/separation to 3 years after the event. Results suggest that early parental divorce/separation is more negatively related to trajectories of internalizing and externalizing problems than is later divorce/separation, whereas later divorce/separation is more negatively related to grades. One implication of these findings is that children may benefit most from interventions focused on preventing internalizing and externalizing problems, whereas adolescents may benefit most from interventions focused on promoting academic achievement. PMID:16756405

Trajectories of internalizing, externalizing, and grades for children who have and have not experienced their parents' divorce or separation.

PubMed

Lansford, Jennifer E; Malone, Patrick S; Castellino, Domini R; Dodge, Kenneth A; Pettit, Gregory S; Bates, John E

2006-06-01

This study examined whether the occurrence and timing of parental separation or divorce was related to trajectories of academic grades and mother- and teacher-reported internalizing and externalizing problems. The authors used hierarchical linear models to estimate trajectories for children who did and did not experience their parents' divorce or separation in kindergarten through 10th grade (N = 194). A novel approach to analyzing the timing of divorce/separation was adopted, and trajectories were estimated from 1 year prior to the divorce/separation to 3 years after the event. Results suggest that early parental divorce/separation is more negatively related to trajectories of internalizing and externalizing problems than is later divorce/separation, whereas later divorce/separation is more negatively related to grades. One implication of these findings is that children may benefit most from interventions focused on preventing internalizing and externalizing problems, whereas adolescents may benefit most from interventions focused on promoting academic achievement. ((c) 2006 APA, all rights reserved).

PTSD symptoms and marital adjustment among ex-POWs' wives.

PubMed

Levin, Yafit; Greene, Talya; Solomon, Zahava

2016-02-01

This study prospectively assessed the implications of war captivity and former prisoners of war's (ex-POWs) posttraumatic stress disorder (PTSD) and PTSD trajectory on their wives' marital adjustment, adjusting for their secondary traumatization (ST). Results show that marital adjustment of the wives of ex-POWs with PTSD (N = 66) was lower compared to wives of ex-POWs (N = 37) and combat veterans (N = 55) without PTSD symptoms. Investigating the possible mechanism underlying the lower marital adjustment, via a mediating model, indicated that husbands' PTSD symptoms mediated the association between captivity and the wives' marital adjustment. Moreover, husbands' PTSD trajectories assessed over 17 years were implicated in their wives' marital adjustment; wives of ex-POWs with chronic PTSD reported lower marital adjustment compared to wives of resilient ex-POWs. The substantial novelty was revealed in prospective deterioration found in dyadic adjustment among wives of ex-POWs with delayed PTSD, but not for wives of chronic or resilient ex-POWs. Implications for research and practice are discussed. (c) 2016 APA, all rights reserved).

Young adults' trajectories of Ecstasy use: a population based study.

PubMed

Smirnov, Andrew; Najman, Jake M; Hayatbakhsh, Reza; Plotnikova, Maria; Wells, Helene; Legosz, Margot; Kemp, Robert

2013-11-01

Young adults' Ecstasy use trajectories have important implications for individual and population-level consequences of Ecstasy use, but little relevant research has been conducted. This study prospectively examines Ecstasy trajectories in a population-based sample. Data are from the Natural History Study of Drug Use, a retrospective/prospective cohort study conducted in Australia. Population screening identified a probability sample of Ecstasy users aged 19-23 years. Complete data for 30 months of follow-up, comprising 4 time intervals, were available for 297 participants (88.4% of sample). Trajectories were derived using cluster analysis based on recent Ecstasy use at each interval. Trajectory predictors were examined using a generalized ordered logit model and included Ecstasy dependence (World Mental Health Composite International Diagnostic Instrument), psychological distress (Hospital Anxiety Depression Scale), aggression (Young Adult Self Report) and contextual factors (e.g. attendance at electronic/dance music events). Three Ecstasy trajectories were identified (low, intermediate and high use). At its peak, the high-use trajectory involved 1-2 days Ecstasy use per week. Decreasing frequency of use was observed for intermediate and high-use trajectories from 12 months, independently of market factors. Intermediate and high-use trajectory membership was predicted by past Ecstasy consumption (>70 pills) and attendance at electronic/dance music events. High-use trajectory members were unlikely to have used Ecstasy for more than 3 years and tended to report consistently positive subjective effects at baseline. Given the social context and temporal course of Ecstasy use, Ecstasy trajectories might be better understood in terms of instrumental rather than addictive drug use patterns. © 2013 Elsevier Ltd. All rights reserved.

An incremental DPMM-based method for trajectory clustering, modeling, and retrieval.

PubMed

Hu, Weiming; Li, Xi; Tian, Guodong; Maybank, Stephen; Zhang, Zhongfei

2013-05-01

Trajectory analysis is the basis for many applications, such as indexing of motion events in videos, activity recognition, and surveillance. In this paper, the Dirichlet process mixture model (DPMM) is applied to trajectory clustering, modeling, and retrieval. We propose an incremental version of a DPMM-based clustering algorithm and apply it to cluster trajectories. An appropriate number of trajectory clusters is determined automatically. When trajectories belonging to new clusters arrive, the new clusters can be identified online and added to the model without any retraining using the previous data. A time-sensitive Dirichlet process mixture model (tDPMM) is applied to each trajectory cluster for learning the trajectory pattern which represents the time-series characteristics of the trajectories in the cluster. Then, a parameterized index is constructed for each cluster. A novel likelihood estimation algorithm for the tDPMM is proposed, and a trajectory-based video retrieval model is developed. The tDPMM-based probabilistic matching method and the DPMM-based model growing method are combined to make the retrieval model scalable and adaptable. Experimental comparisons with state-of-the-art algorithms demonstrate the effectiveness of our algorithm.

14 CFR Appendix B to Part 420 - Method for Defining a Flight Corridor

Code of Federal Regulations, 2010 CFR

2010-01-01

... trajectory simulation software. Trajectory time intervals shall be no greater than one second. If an... applicant shall construct a launch area of a flight corridor using the processes and equations of this paragraph for each trajectory position. An applicant shall repeat these processes at time points on the...

Predicting Adolescents' Bullying Participation from Developmental Trajectories of Social Status and Behavior.

PubMed

Pouwels, J Loes; Salmivalli, Christina; Saarento, Silja; van den Berg, Yvonne H M; Lansu, Tessa A M; Cillessen, Antonius H N

2017-03-28

The aim of this study was to determine how trajectory clusters of social status (social preference and perceived popularity) and behavior (direct aggression and prosocial behavior) from age 9 to age 14 predicted adolescents' bullying participant roles at age 16 and 17 (n = 266). Clusters were identified with multivariate growth mixture modeling (GMM). The findings showed that participants' developmental trajectories of social status and social behavior across childhood and early adolescence predicted their bullying participant role involvement in adolescence. Practical implications and suggestions for further research are discussed. © 2017 The Authors. Child Development published by Wiley Periodicals, Inc. on behalf of Society for Research in Child Development.

Dismantling the present and future threats of testicular cancer: a grounded theory of positive and negative adjustment trajectories.

PubMed

Matheson, Lauren; Boulton, Mary; Lavender, Verna; Protheroe, Andrew; Brand, Sue; Wanat, Marta; Watson, Eila

2016-02-01

Testicular cancer commonly affects men in the prime of their lives. While survival rates are excellent, little previous research has examined men's experiences of adjustment to survivorship. We aimed to explore this issue in younger testicular cancer survivors. In-depth qualitative interviews were conducted with testicular cancer survivors over two time points approximately 6 months apart in the year following treatment completion. Interviews were analysed using a grounded theory approach. The sample included 18 testicular cancer survivors between 22 and 44 years (mean age 34). A grounded theory was developed, which explained the process of positive adjustment over the first year following the treatment completion in terms of men's ability to dismantle the present and future threats of cancer, involving the key transitions of gaining a sense of perspective and striving to get on with life and restore normality. These were facilitated by six key processes. The processes that explained a negative adjustment trajectory are also presented. These findings contribute to the understanding of the psychosocial impact of testicular cancer on younger men's lives and have implications for the provision of support to testicular cancer survivors. Further investigation into the feasibility of one-on-one peer support interventions is warranted, as well as informal support that respects men's desire for independence. Understanding the processes involved in adjustment highlights ways in which health professionals can offer support to those struggling to adjust through challenging illness beliefs, encouraging emotional disclosure and facilitating peer mentoring.

Final STS-11 (41-B) best estimate trajectory products: Development and results from the first Cape landing

NASA Technical Reports Server (NTRS)

Kelly, G. M.; Mcconnell, J. G.; Findlay, J. T.; Heck, M. L.; Henry, M. W.

1984-01-01

The STS-11 (41-B) postflight data processing is completed and the results published. The final reconstructed entry trajectory is presented. The various atmospheric sources available for this flight are discussed. Aerodynamic Best Estimate of Trajectory BET generation and plots from this file are presented. A definition of the major maneuvers effected is given. Physical constants, including spacecraft mass properties; final residuals from the reconstruction process; trajectory parameter listings; and an archival section are included.

The Emergence of a Binational Mexico-US Workforce: Implications for Farm Labor Workforce Security.

ERIC Educational Resources Information Center

Kissam, Edward; Intili, Jo Ann; Garcia, Anna

The U.S. agricultural labor market is already, in many respects, a binational one, and it will become increasingly one in which workers who are born in Mexico will follow a variety of worklife trajectories that take them back and forth between both countries. Recognition of this reality has important implications for policy development and program…

Longitudinal modelling of theory-based depressive vulnerabilities, depression trajectories and poor outcomes post-ACS.

PubMed

Keegan, Conor; Conroy, Ronán; Doyle, Frank

2016-02-01

Depression is associated with increased mortality in patients with acute coronary syndrome (ACS). However, little is known about the theoretical causes of depression trajectories post-ACS, and whether these trajectories predict subsequent morbidity/mortality. We tested a longitudinal model of depressive vulnerabilities, trajectories and mortality. A prospective observational study of 374 ACS patients was conducted. Participants completed questionnaires on theoretical vulnerabilities (interpersonal life events, reinforcing events, cognitive distortions, and Type D personality) during hospitalisation and depression at baseline and 3, 6 and 12 months post-hospitalisation. Latent class analysis determined trajectories of depression. Path analysis was used to test relationships among vulnerabilities, depression trajectories and outcomes (combination of 1-year morbidity and 7-year mortality). Vulnerabilities independently predicted persistent and subthreshold depression trajectory categories, with effect sizes significantly highest for persistent depression. Both subthreshold and persistent depression trajectories were significant predictors of morbidity/mortality (e.g. persistent depression OR=2.4, 95% CI=1.8-3.1, relative to never depressed). Causality cannot be inferred from these associations. We had no measures of history of depression or treatments, which may affect associations. Theoretical vulnerabilities predicted depression trajectories, which in turn predicted increased morbidity/mortality, demonstrating for the first time a potential longitudinal chain of events post-ACS. This longitudinal model has important practical implications as clinicians can use vulnerability measures to identify those at most risk of poor outcomes. Copyright © 2015. Published by Elsevier B.V.

Connecting the dots across time: reconstruction of single-cell signalling trajectories using time-stamped data

NASA Astrophysics Data System (ADS)

Mukherjee, Sayak; Stewart, David; Stewart, William; Lanier, Lewis L.; Das, Jayajit

2017-08-01

Single-cell responses are shaped by the geometry of signalling kinetic trajectories carved in a multidimensional space spanned by signalling protein abundances. It is, however, challenging to assay a large number (more than 3) of signalling species in live-cell imaging, which makes it difficult to probe single-cell signalling kinetic trajectories in large dimensions. Flow and mass cytometry techniques can measure a large number (4 to more than 40) of signalling species but are unable to track single cells. Thus, cytometry experiments provide detailed time-stamped snapshots of single-cell signalling kinetics. Is it possible to use the time-stamped cytometry data to reconstruct single-cell signalling trajectories? Borrowing concepts of conserved and slow variables from non-equilibrium statistical physics we develop an approach to reconstruct signalling trajectories using snapshot data by creating new variables that remain invariant or vary slowly during the signalling kinetics. We apply this approach to reconstruct trajectories using snapshot data obtained from in silico simulations, live-cell imaging measurements, and, synthetic flow cytometry datasets. The application of invariants and slow variables to reconstruct trajectories provides a radically different way to track objects using snapshot data. The approach is likely to have implications for solving matching problems in a wide range of disciplines.

Vertical Transport of Aerosol Particles across Mountain Topography near the Los Angeles Basin

NASA Astrophysics Data System (ADS)

Murray, J. J.; Schill, S.; Freeman, S.; Bertram, T. H.; Lefer, B. L.

2015-12-01

Transport of aerosol particles is known to affect air quality and is largely dependent on the characteristic topography of the surrounding region. To characterize this transport, aerosol number distributions were collected with an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS, DMT) during the 2015 NASA Student Airborne Research Program (SARP) in and around the Los Angeles Basin in Southern California. Increases in particle number concentration and size were observed over mountainous terrain north of Los Angeles County. Chemical analysis and meteorological lagrangian trajectories suggest orographic lifting processes, known as the "chimney effect". Implications for spatial transport and distribution will be discussed.

Trajectory Optimization for Missions to Small Bodies with a Focus on Scientific Merit.

PubMed

Englander, Jacob A; Vavrina, Matthew A; Lim, Lucy F; McFadden, Lucy A; Rhoden, Alyssa R; Noll, Keith S

2017-01-01

Trajectory design for missions to small bodies is tightly coupled both with the selection of targets for a mission and with the choice of spacecraft power, propulsion, and other hardware. Traditional methods of trajectory optimization have focused on finding the optimal trajectory for an a priori selection of destinations and spacecraft parameters. Recent research has expanded the field of trajectory optimization to multidisciplinary systems optimization that includes spacecraft parameters. The logical next step is to extend the optimization process to include target selection based not only on engineering figures of merit but also scientific value. This paper presents a new technique to solve the multidisciplinary mission optimization problem for small-bodies missions, including classical trajectory design, the choice of spacecraft power and propulsion systems, and also the scientific value of the targets. This technique, when combined with modern parallel computers, enables a holistic view of the small body mission design process that previously required iteration among several different design processes.

The language growth of spanish-speaking English language learners.

PubMed

Rojas, Raúl; Iglesias, Aquiles

2013-01-01

Although the research literature regarding language growth trajectories is burgeoning, the shape and direction of English Language Learners' (ELLs) language growth trajectories are largely not known. This study used growth curve modeling to determine the shape of ELLs' language growth trajectories across 12,248 oral narrative language samples (6,516 Spanish; 5,732 English) produced by 1,723 ELLs during the first 3 years of formal schooling (M age at first observation = 5 years 7 months). Results indicated distinct trajectories of language growth over time for each language differentially impacted by summer vacation and gender, significant intra- and interindividual differences in initial status and growth rates across both languages, and language-specific relations between language growth and initial status. Implications of ELLs' language growth are discussed. © 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.

The Development of Self-Regulation across Early Childhood

PubMed Central

Montroy, Janelle J.; Bowles, Ryan P.; Skibbe, Lori E.; McClelland, Megan M.; Morrison, Frederick J.

2016-01-01

The development of early childhood self-regulation is often considered an early life marker for later life successes. Yet little longitudinal research has evaluated whether there are different trajectories of self-regulation development across children. This study investigates the development of behavioral self-regulation between the ages of three and seven, with a direct focus on possible heterogeneity in the developmental trajectories, and a set of potential indicators that distinguish unique behavioral self-regulation trajectories. Across three diverse samples, 1,386 children were assessed on behavioral self-regulation from preschool through first grade. Results indicated that majority of children develop self-regulation rapidly during early childhood, and that children follow three distinct developmental patterns of growth. These three trajectories were distinguishable based on timing of rapid gains, as well as child gender, early language skills, and maternal education levels. Findings highlight early developmental differences in how self-regulation unfolds with implications for offering individualized support across children. PMID:27709999

Adolescent Attachment and Trajectories of Hostile-Impulsive Behavior: Implications for the Development of Personality Disorders

PubMed Central

Kobak, Roger; Zajac, Kristyn; Smith, Clare

2014-01-01

Adolescents’ trajectories of impulsive and hostile behaviors provide a dynamic index of risk for the emergence of Cluster B (Anti-social and Borderline) personality disorders in early adulthood. In the current study, we tested the hypothesis that Preoccupied states of mind in the Adult Attachment Interview would increase both the level and rate of growth in adolescents’ trajectories of aggressive and sexual risk-taking behaviors measured at ages 13, 15, and 17. Overall, Preoccupied states of mind predicted higher levels of sexual risk-taking and aggressive behaviors across all three assessments as well as higher rates of growth in sexual-risk taking and caregiver-reported aggression over time. In addition, Preoccupied females showed slower rates of decline in self-reported hostile emotions than did Preoccupied males. The effects of gender as a moderator of the relations between Preoccupied status and risk trajectories for personality disorders are discussed. PMID:19583886

Trajectories on the path to reciprocity-A theoretical framework for collaborating with socioeconomically disadvantaged communities.

PubMed

Minas, Maria; Ribeiro, Maria Teresa; Anglin, James P

2018-01-01

The importance of cultivating connection to enhance individual, relational and collective well-being is gaining attention in the current literature on building community. Although these goals are being increasingly considered, the concept of reciprocity has been less prominent than may be warranted in the field of psychology. This article presents a theoretical framework on the dynamics of reciprocity which resulted from grounded theory (GT) research involving 2 complementary studies. The first study involved 22 participants from different socioeconomic backgrounds engaged in "reflecting-team with appreciative audiences" sessions (Madsen, 2007) in Portugal. The second study involved participant observation of 15 community programs recognized as good-practices in collaboration with socioeconomically disadvantaged participants, at national and international levels, across 9 countries. The theoretical framework emphasizes the centrality of building reciprocity for the development of individuals, families, communities, and programs. It integrates the trajectories of reciprocity; quadrants reflecting the standpoints assumed according to socioeconomic and cultural positions; basic social-psychological processes inherent to the process of building reciprocity; and characterizes different types of programs. The resulting framework is analyzed in relation to prior literature for a broader understanding of synergies and challenges, and the article concludes by suggesting implications for further research and practice. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A Robot Trajectory Optimization Approach for Thermal Barrier Coatings Used for Free-Form Components

NASA Astrophysics Data System (ADS)

Cai, Zhenhua; Qi, Beichun; Tao, Chongyuan; Luo, Jie; Chen, Yuepeng; Xie, Changjun

2017-10-01

This paper is concerned with a robot trajectory optimization approach for thermal barrier coatings. As the requirements of high reproducibility of complex workpieces increase, an optimal thermal spraying trajectory should not only guarantee an accurate control of spray parameters defined by users (e.g., scanning speed, spray distance, scanning step, etc.) to achieve coating thickness homogeneity but also help to homogenize the heat transfer distribution on the coating surface. A mesh-based trajectory generation approach is introduced in this work to generate path curves on a free-form component. Then, two types of meander trajectories are generated by performing a different connection method. Additionally, this paper presents a research approach for introducing the heat transfer analysis into the trajectory planning process. Combining heat transfer analysis with trajectory planning overcomes the defects of traditional trajectory planning methods (e.g., local over-heating), which helps form the uniform temperature field by optimizing the time sequence of path curves. The influence of two different robot trajectories on the process of heat transfer is estimated by coupled FEM models which demonstrates the effectiveness of the presented optimization approach.

New biomarkers of post-settlement growth in the sea urchin Strongylocentrotus purpuratus.

PubMed

Fadl, Alyaa Elsaid Abdelaziz; Mahfouz, Magdy Elsayed; El-Gamal, Mona Mabrouk Taha; Heyland, Andreas

2017-10-01

Some sea urchins, including the purple sea urchin Strongylocentrotus purpuratus, have been successfully used in aquaculture, but their slow growth and late reproduction are challenging to overcome when developing efficient aquaculture production techniques. S. purpuratus develops via an indirect life history that is characterized by a drastic settlement process at the end of a larval period that lasts for several weeks. During this transition, the bilateral larva is transformed into a pentaradial juvenile, which will start feeding and growing in the benthic habitat. Due to predation and other ecological factors, settlement is typically associated with high mortality rates in juvenile populations. Additionally, juveniles require several days to develop a functional mouth and digestive system. During this perimetamorphic period, juveniles use up larval resources until they are capable to digest adult food. Mechanisms underlying the onset of juvenile feeding and metabolism have implications for the recruitment of natural populations as well as aquaculture and are relatively poorly understood in S. purpuratus . The insulin/insulin-like growth factor signalling (IIS)/Target of Rapamycin (TOR) pathway (IIS/TOR) is well conserved among animal phyla and regulates physiological and developmental functions, such as growth, reproduction, aging and nutritional status. We analyzed the expression of FoxO, TOR, and ILPs in post-settlement juveniles in conjunction with their early growth trajectories. We also tested how pre-settlement starvation affected post-settlement expression of IIS. We found that FoxO provides a useful molecular marker in early juveniles as its expression is strongly correlated with juvenile growth. We also found that pre-settlement starvation affects juvenile growth trajectories as well as IIS. Our findings provide preliminary insights into the mechanisms underlying post-settlement growth and metabolism in S. purpuratus . They also have important implications for sea urchin aquaculture, as they show that pre-settlement nutrient environment significantly affects both early growth trajectories and gene expression. This information can be used to develop new biomarkers for juvenile health in sea urchin population ecology and aquaculture aquaculture.

Annual Research Review: Positive adjustment to adversity -Trajectories of minimal-impact resilience and emergent resilience

PubMed Central

Bonanno, George A.; Diminich, Erica D.

2012-01-01

Background Research on resilience in the aftermath of potentially traumatic life events is still evolving. For decades researchers have documented resilience in children exposed to corrosive early environments, such as poverty or chronic maltreatment. Relatively more recently the study of resilience has migrated to the investigation of isolated and potentially traumatic life events (PTE) in adults. Methods In this article we first consider some of the key differences in the conceptualization of resilience following chronic adversity versus resilience following single-incident traumas, and then describe some of the misunderstandings that have developed about these constructs. To organize our discussion we introduce the terms emergent resilience and minimal-impact resilience to represent trajectories positive adjustment in these two domains, respectively. Results We focused in particular on minimal-impact resilience, and reviewed recent advances in statistical modeling of latent trajectories that have informed the most recent research on minimal-impact resilience in both children and adults and the variables that predict it, including demographic variables, exposure, past and current stressors, resources, personality, positive emotion, coping and appraisal, and flexibility in coping and emotion regulation. Conclusions The research on minimal impact resilience is nascent. Further research is warranted with implications for a multiple levels of analysis approach to elucidate the processes that may mitigate or modify the impact of a PTE at different developmental stages. PMID:23215790

The social practice of rescue: the safety implications of acute illness trajectories and patient categorisation in medical and maternity settings.

PubMed

Mackintosh, Nicola; Sandall, Jane

2016-02-01

The normative position in acute hospital care when a patient is seriously ill is to resuscitate and rescue. However, a number of UK and international reports have highlighted problems with the lack of timely recognition, treatment and referral of patients whose condition is deteriorating while being cared for on hospital wards. This article explores the social practice of rescue, and the structural and cultural influences that guide the categorisation and ordering of acutely ill patients in different hospital settings. We draw on Strauss et al.'s notion of the patient trajectory and link this with the impact of categorisation practices, thus extending insights beyond those gained from emergency department triage to care management processes further downstream on the hospital ward. Using ethnographic data collected from medical wards and maternity care settings in two UK inner city hospitals, we explore how differences in population, cultural norms, categorisation work and trajectories of clinical deterioration interlink and influence patient safety. An analysis of the variation in findings between care settings and patient groups enables us to consider socio-political influences and the specifics of how staff manage trade-offs linked to the enactment of core values such as safety and equity in practice. © 2015 The Authors. Sociology of Health & Illness published by John Wiley & Sons Ltd on behalf of Foundation for SHIL.

Towards Autonomous Airport Surface Operations: NextGen Flight Deck Implications

NASA Technical Reports Server (NTRS)

Foyle, David C.; Hooey, Becky Lee; Bakowski, Deborah Lee

2017-01-01

Surface Trajectory-based Operations (STBO) is a potential concept candidate for flight deck autonomous operations. Existing research will be reviewed and possible architectures and research issues will be presented.

Trajectory optimization for an asymmetric launch vehicle. M.S. Thesis - MIT

NASA Technical Reports Server (NTRS)

Sullivan, Jeanne Marie

1990-01-01

A numerical optimization technique is used to fully automate the trajectory design process for an symmetric configuration of the proposed Advanced Launch System (ALS). The objective of the ALS trajectory design process is the maximization of the vehicle mass when it reaches the desired orbit. The trajectories used were based on a simple shape that could be described by a small set of parameters. The use of a simple trajectory model can significantly reduce the computation time required for trajectory optimization. A predictive simulation was developed to determine the on-orbit mass given an initial vehicle state, wind information, and a set of trajectory parameters. This simulation utilizes an idealized control system to speed computation by increasing the integration time step. The conjugate gradient method is used for the numerical optimization of on-orbit mass. The method requires only the evaluation of the on-orbit mass function using the predictive simulation, and the gradient of the on-orbit mass function with respect to the trajectory parameters. The gradient is approximated with finite differencing. Prelaunch trajectory designs were carried out using the optimization procedure. The predictive simulation is used in flight to redesign the trajectory to account for trajectory deviations produced by off-nominal conditions, e.g., stronger than expected head winds.

Clonal evolution in hematologic malignancies and therapeutic implications

PubMed Central

Landau, Dan A.; Carter, Scott L.; Getz, Gad; Wu, Catherine J.

2014-01-01

The ability of cancer to evolve and adapt is a principal challenge to therapy in general, and to the paradigm of targeted therapy in particular. This ability is fueled by the co-existence of multiple, genetically heterogeneous subpopulations within the cancer cell population. Increasing evidence has supported the idea that these subpopulations are selected in a Darwinian fashion, by which the genetic landscape of the tumor is continuously reshaped. Massively parallel sequencing has enabled a recent surge in our ability to study this process, adding to previous efforts using cytogenetic methods and targeted sequencing. Altogether, these studies reveal the complex evolutionary trajectories occurring across individual hematological malignancies. They also suggest that while clonal evolution may contribute to resistance to therapy, treatment may also hasten the evolutionary process. New insights into this process challenge us to understand the impact of treatment on clonal evolution, and inspire the development of novel prognostic and therapeutic strategies. PMID:23979521

Migration and HIV risk: Life histories of Mexican-born men living with HIV in North Carolina

PubMed Central

Mann, Lilli; Valera, Erik; Hightow-Weidman, Lisa B.; Barrington, Clare

2015-01-01

Latino men in the Southeastern USA are disproportionately affected by HIV, but little is known about how the migration process influences HIV-related risk. In North Carolina (NC), a relatively new immigrant destination, Latino men are predominantly young and from Mexico. We conducted 31 iterative life history interviews with 15 Mexican-born men living with HIV. We used holistic content narrative analysis methods to examine HIV vulnerability in the context of migration and to identify important turning points. Major themes included the prominence of traumatic early life experiences, migration as an ongoing process rather than a finite event, and HIV diagnosis as a final turning point in migration trajectories. Findings provide a nuanced understanding of HIV vulnerability throughout the migration process and have implications including the need for bi-national HIV prevention approaches, improved outreach around early testing and linkage to care, and attention to mental health. PMID:24866206

RESILIENCE THEORY AND ITS IMPLICATIONS FOR CHINESE ADOLESCENTS.

PubMed

Wang, Jin-Liang; Zhang, Da-Jun; Zimmerman, Marc A

2015-10-01

Over the past 20 years, resilience theory has attracted great attention from both researchers and mental health practitioners. Resilience is defined as a process of overcoming the negative effects of risk exposure, coping successfully with traumatic experiences, or avoiding the negative trajectories associated with risks. Three basic models of resilience have been proposed to account for the mechanism whereby promotive factors operate to alter the trajectory from risk exposure to negative consequences: compensatory model, protective model, and inoculation model. Assets and resources are two types of promotive factors found to be effective in decreasing internalizing and externalizing problems. Considering the protective or compensatory role of assets and resources in helping youth be resilient against negative effects of adversity, resilience could be applied to Chinese migrant and left-behind children who are at risk for internalizing (e.g., depression, anxiety) and externalizing problems (e.g., delinquent behaviors, cigarette and alcohol use). Additionally, psychological suzhi-based interventions, a mental health construct for individuals that focuses on a strengths-based approach, can be integrated with resilience-based approach to develop more balanced programs for positive youth development.

How Evolution May Work Through Curiosity-Driven Developmental Process.

PubMed

Oudeyer, Pierre-Yves; Smith, Linda B

2016-04-01

Infants' own activities create and actively select their learning experiences. Here we review recent models of embodied information seeking and curiosity-driven learning and show that these mechanisms have deep implications for development and evolution. We discuss how these mechanisms yield self-organized epigenesis with emergent ordered behavioral and cognitive developmental stages. We describe a robotic experiment that explored the hypothesis that progress in learning, in and for itself, generates intrinsic rewards: The robot learners probabilistically selected experiences according to their potential for reducing uncertainty. In these experiments, curiosity-driven learning led the robot learner to successively discover object affordances and vocal interaction with its peers. We explain how a learning curriculum adapted to the current constraints of the learning system automatically formed, constraining learning and shaping the developmental trajectory. The observed trajectories in the robot experiment share many properties with those in infant development, including a mixture of regularities and diversities in the developmental patterns. Finally, we argue that such emergent developmental structures can guide and constrain evolution, in particular with regard to the origins of language. Copyright © 2016 Cognitive Science Society, Inc.

Lunar Landing Trajectory Design for Onboard Hazard Detection and Avoidance

NASA Technical Reports Server (NTRS)

Paschall, Steve; Brady, Tye; Sostaric, Ron

2009-01-01

The Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project is developing the software and hardware technology needed to support a safe and precise landing for the next generation of lunar missions. ALHAT provides this capability through terrain-relative navigation measurements to enhance global-scale precision, an onboard hazard detection system to select safe landing locations, and an Autonomous Guidance, Navigation, and Control (AGNC) capability to process these measurements and safely direct the vehicle to a landing location. This paper focuses on the key trajectory design issues relevant to providing an onboard Hazard Detection and Avoidance (HDA) capability for the lander. Hazard detection can be accomplished by the crew visually scanning the terrain through a window, a sensor system imaging the terrain, or some combination of both. For ALHAT, this hazard detection activity is provided by a sensor system, which either augments the crew s perception or entirely replaces the crew in the case of a robotic landing. Detecting hazards influences the trajectory design by requiring the proper perspective, range to the landing site, and sufficient time to view the terrain. Following this, the trajectory design must provide additional time to process this information and make a decision about where to safely land. During the final part of the HDA process, the trajectory design must provide sufficient margin to enable a hazard avoidance maneuver. In order to demonstrate the effects of these constraints on the landing trajectory, a tradespace of trajectory designs was created for the initial ALHAT Design Analysis Cycle (ALDAC-1) and each case evaluated with these HDA constraints active. The ALHAT analysis process, described in this paper, narrows down this tradespace and subsequently better defines the trajectory design needed to support onboard HDA. Future ALDACs will enhance this trajectory design by balancing these issues and others in an overall system design process.

Trajectory Optimization of Electric Aircraft Subject to Subsystem Thermal Constraints

NASA Technical Reports Server (NTRS)

Falck, Robert D.; Chin, Jeffrey C.; Schnulo, Sydney L.; Burt, Jonathan M.; Gray, Justin S.

2017-01-01

Electric aircraft pose a unique design challenge in that they lack a simple way to reject waste heat from the power train. While conventional aircraft reject most of their excess heat in the exhaust stream, for electric aircraft this is not an option. To examine the implications of this challenge on electric aircraft design and performance, we developed a model of the electric subsystems for the NASA X-57 electric testbed aircraft. We then coupled this model with a model of simple 2D aircraft dynamics and used a Legendre-Gauss-Lobatto collocation optimal control approach to find optimal trajectories for the aircraft with and without thermal constraints. The results show that the X-57 heat rejection systems are well designed for maximum-range and maximum-efficiency flight, without the need to deviate from an optimal trajectory. Stressing the thermal constraints by reducing the cooling capacity or requiring faster flight has a minimal impact on performance, as the trajectory optimization technique is able to find flight paths which honor the thermal constraints with relatively minor deviations from the nominal optimal trajectory.

Longitudinal Examination of Aggression and Study Skills From Middle to High School: Implications for Dropout Prevention.

PubMed

Orpinas, Pamela; Raczynski, Katherine; Hsieh, Hsien-Lin; Nahapetyan, Lusine; Horne, Arthur M

2018-03-01

High school completion provides health and economic benefits. The purpose of this study is to describe dropout rates based on longitudinal trajectories of aggression and study skills using teacher ratings. The sample consisted of 620 randomly selected sixth graders. Every year from Grade 6 to 12, a teacher completed a nationally normed behavioral rating scale. We used latent class mixture modeling to identify the trajectories. Participants followed 3 trajectories of aggression (Low, Medium Desisting, and High Desisting) and 5 trajectories of study skills (Low, Average-Low, Decreasing, Increasing, and High). Over three-quarters of the sample were in stable trajectories of study skills over time. Most students in the High Desisting Aggression group were in the Low Study Skills group, and all students in the High Study Skills group were in the Low Aggression group. The overall dropout rate was 17%, but varied dramatically across combined aggression and study skills groups, ranging from 2% to 50%. The results highlight the importance of early prevention that combines academic enhancement and behavioral management for reducing school dropout. © 2018, American School Health Association.

Trajectories of Childbearing among HIV Infected Indian Women: A Sequence Analysis Approach

PubMed Central

Darak, Shrinivas; Mills, Melinda; Kulkarni, Vinay; Kulkarni, Sanjeevani; Hutter, Inge; Janssen, Fanny

2015-01-01

Background HIV infection closely relates to and deeply affects the reproductive career of those infected. However, little is known about the reproductive career trajectories, specifically the interaction of the timing of HIV diagnosis with the timing and sequencing of reproductive events among HIV infected women. This is the first study to describe and typify this interaction. Methods Retrospective calendar data of ever married HIV infected women aged 15-45 attending a HIV clinic in Pune, Maharashtra, Western India (N=622) on reproductive events such as marriage, cohabitation with the partner, use of contraception, pregnancy, childbirth and HIV diagnosis were analyzed using sequence analysis and multinomial logistic regression. Results Optimal matching revealed three distinct trajectories: 1) HIV diagnosis concurrent with childbearing (40.7%), 2) HIV diagnosis after childbearing (32.1%), and 3) HIV diagnosis after husband’s death (27.2%). Multinomial logistic regression (trajectory 1 = baseline) showed that women who got married before the age of 21 years and who had no or primary level education had a significantly higher risk of knowing their HIV status either after childbearing or close to their husband’s death. The risk of HIV diagnosis after husband’s death was also higher among rural women and those who were diagnosed before 2005. Conclusions Three distinct patterns of interaction of timing of HIV diagnosis with timing and sequencing of events in the reproductive career were observed that have clear implications for (i) understanding of the individual life planning process in the context of HIV, (ii) formulation of assumptions for estimating HIV infected women in need of PMTCT services, and (iii) provision of care services. PMID:25906185

Long-term consequences of membership in trajectory groups of delinquent behavior in an urban sample: violence, drug use, interpersonal, and neighborhood attributes.

PubMed

Brook, Judith S; Lee, Jung Yeon; Finch, Stephen J; Brown, Elaine N; Brook, David W

2013-01-01

Research on stability and change in delinquent behavior over time has important implications for both the individual and the criminal justice system. The present research looks at this issue by examining the associations between the trajectories of delinquent behavior in adolescence and adult functioning. Data for the present study are from a four-wave longitudinal study of African American and Hispanic participants. Participants provided information at mean ages 14, 19, 24, and 29. We used growth mixture modeling to extract trajectory groups of delinquent behavior in adolescence and young adulthood. Regression analyses were conducted to examine whether memberships in the trajectory groups of delinquent behavior from mean age 14 to mean age 24 were associated with violence, substance abuse and dependence, partner discord, peer substance use, and residence in a high-crime neighborhood at mean age 29 when compared with the reference trajectory group of participants with low or no delinquent behavior. Four trajectory groups of delinquent behavior were identified: the no/low, the decreasing, the moderate, and the high persistent trajectory groups. Memberships in the trajectory groups were significantly correlated with variations in adult functioning. Memberships in some trajectory groups of delinquent behavior are significant predictors of later violent behavior, substance abuse and dependence, partner discord, peer substance use, and residence in a high-crime neighborhood. The findings reinforce the importance of investing in interventions to address different patterns of delinquent behavior. Findings are discussed in relation to previous investigations with non-Hispanic White samples. © 2013 Wiley Periodicals, Inc.

Work functioning trajectories in cancer patients: Results from the longitudinal Work Life after Cancer (WOLICA) study.

PubMed

Dorland, Heleen F; Abma, Femke I; Roelen, Corné A M; Stewart, Roy E; Amick, Benjamin C; Ranchor, Adelita V; Bültmann, Ute

2017-11-01

More than 60% of cancer patients are able to work after cancer diagnosis. However, little is known about their functioning at work. Therefore, the aims of this study were to (1) identify work functioning trajectories in the year following return to work (RTW) in cancer patients and (2) examine baseline sociodemographic, health-related and work-related variables associated with work functioning trajectories. This longitudinal cohort study included 384 cancer patients who have returned to work after cancer diagnosis. Work functioning was measured at baseline, 3, 6, 9 and 12 months follow-up. Latent class growth modeling (LCGM) was used to identify work functioning trajectories. Associations of baseline variables with work functioning trajectories were examined using univariate and multivariate analyses. LCGM analyses with cancer patients who completed on at least three time points the Work Role Functioning Questionnaire (n = 324) identified three work functioning trajectories: "persistently high" (16% of the sample), "moderate to high" (54%) and "persistently low" work functioning (32%). Cancer patients with persistently high work functioning had less time between diagnosis and RTW and had less often a changed meaning of work, while cancer patients with persistently low work functioning reported more baseline cognitive symptoms compared to cancer patients in the other trajectories. This knowledge has implications for cancer care and guidance of cancer patients at work. © 2017 UICC.

Lander Trajectory Reconstruction computer program

NASA Technical Reports Server (NTRS)

Adams, G. L.; Bradt, A. J.; Ferguson, J. B.; Schnelker, H. J.

1971-01-01

The Lander Trajectory Reconstruction (LTR) computer program is a tool for analysis of the planetary entry trajectory and atmosphere reconstruction process for a lander or probe. The program can be divided into two parts: (1) the data generator and (2) the reconstructor. The data generator provides the real environment in which the lander or probe is presumed to find itself. The reconstructor reconstructs the entry trajectory and atmosphere using sensor data generated by the data generator and a Kalman-Schmidt consider filter. A wide variety of vehicle and environmental parameters may be either solved-for or considered in the filter process.

Actin-based motility of Listeria: Right-handed helical trajectories

NASA Astrophysics Data System (ADS)

Rangarajan, Murali

2012-06-01

Bacteria such as Listeria monocytogenes recruit cellular machinery to move in and between cells. Understanding the mechanism of motility, including force and torque generation and the resultant displacements, holds keys to numerous applications in medicine and biosensing. In this work, a simple back-of-the-envelope calculation is presented to illustrate that a biomechanical model of actin-based motility of a rigid surface through persistently attached filaments propelled by affinity-modulated molecular motors can produce a right-handed helical trajectory consistent with experimental observations. The implications of the mechanism to bacterial motility are discussed.

Autism Symptomatology in Boys with Fragile X Syndrome: A Cross Sectional Developmental Trajectories Comparison with Nonsyndromic Autism Spectrum Disorder

PubMed Central

Thurman, Angela John; McDuffie, Andrea; Kover, Sara T.; Hagerman, Randi J.; Abbeduto, Leonard

2015-01-01

Although males with fragile X syndrome (FXS) are frequently described as demonstrating autism symptomatology, there is much debate regarding whether the behavioral symptoms representing the core domains of autism are the result of the same or different underlying neurological/psychological mechanisms. The present study used a cross-sectional developmental trajectories approach to compare the profiles of autism symptomatology relative to chronological age (CA), nonverbal IQ, and expressive vocabulary ability between individuals with FXS and individuals with nonsyndromic ASD. Results suggest that the onset of autism symptoms and their developmental trajectories in males with FXS differ in important ways as a function of chronological age, nonverbal cognitive ability, and expressive vocabulary relative to males with nonsyndromic ASD. Theoretical and clinical implications are discussed. PMID:25904201

Ups and downs of the expatriate experience? Understanding work adjustment trajectories and career outcomes.

PubMed

Zhu, Jing; Wanberg, Connie R; Harrison, David A; Diehn, Erica W

2016-04-01

We examine changes in work adjustment among 179 expatriates from 3 multinational organizations from predeparture through the first 9 months of a new international assignment. Our 10-wave results challenge classic U-shaped theories of expatriate adjustment (e.g., Torbiorn, 1982). Consistent with uncertainty reduction theory, our results instead suggest that expatriates typically experience a gradual increase in work adjustment over time. Two resources that expatriates bring to their assignments (previous culture-specific work experience and core self-evaluations) moderate the trajectory of work adjustment. Trajectory of adjustment predicts Month 9 career instrumentality and turnover intention, as well as career advancement (job promotion) 1.5 years further. Implications for theory, as well as for changes in expatriate management practices, are discussed. (c) 2016 APA, all rights reserved).

Technology and operational considerations for low-heat-rate trajectories. [of future winged earth reentry vehicles

NASA Technical Reports Server (NTRS)

Wurster, K. E.; Eldred, C. H.

1979-01-01

A broad parametric study which examines several critical aspects of low-heat-rate entry trajectories is performed. Low planform loadings associated with future winged earth-entry vehicles coupled with the potential application of metallic thermal protection systems (TPS) suggest that such trajectories are of particular interest. Studied are three heating conditions - reference, stagnation, and windward centerline, for both laminar and turbulent flow; configuration-related factors including planform loading and hypersonic angle of attack; and mission-related factors such as cross-range and orbit inclination. Results indicate benefits in the design of TPS to be gained by utilizing moderate angles of attack as opposed to high-lift coefficient, high angles of attack, during entry. An assessment of design and technology implications is made.

Symptom Trajectories Among Child Survivors of Maltreatment: Findings from the Longitudinal Studies of Child Abuse and Neglect (LONGSCAN).

PubMed

Lauterbach, Dean; Armour, Cherie

2016-02-01

Very few studies have investigated the longitudinal trajectory of depression and anxiety related symptomatology among child victims of maltreatment or among those at risk for maltreatment. The current study examined latent class trajectories of anxiety/depression symptoms in a sample of 1354 (n = 657 boys, n = 697 girls) victimized or at risk children using data collected from the Longtitudinal Studies of Child Abuse and Neglect (LONGSCAN). Four trajectory groups were identified labeled low-stable, moderate-stable, moderate-increasing, and high-decreasing. This study also sought to investigate predictors of group membership. Relative to the low-stable group, membership in the three more pathological groups (i.e., moderate-stable, moderate-increasing, and high-decreasing) was predicted by a greater number of maltreatment allegations, more visits to a primary care physician for psychological issues, less perceived support by primary maternal caregiver, and lower rated popularity of the child. Implications for early identification of child maltreatment victims in primary health care settings was discussed.

The development of self-regulation across early childhood.

PubMed

Montroy, Janelle J; Bowles, Ryan P; Skibbe, Lori E; McClelland, Megan M; Morrison, Frederick J

2016-11-01

The development of early childhood self-regulation is often considered an early life marker for later life successes. Yet little longitudinal research has evaluated whether there are different trajectories of self-regulation development across children. This study investigates the development of behavioral self-regulation between the ages of 3 and 7 years, with a direct focus on possible heterogeneity in the developmental trajectories, and a set of potential indicators that distinguish unique behavioral self-regulation trajectories. Across 3 diverse samples, 1,386 children were assessed on behavioral self-regulation from preschool through first grade. Results indicated that majority of children develop self-regulation rapidly during early childhood, and that children follow 3 distinct developmental patterns of growth. These 3 trajectories were distinguishable based on timing of rapid gains, as well as child gender, early language skills, and maternal education levels. Findings highlight early developmental differences in how self-regulation unfolds, with implications for offering individualized support across children. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Associations of Family and Peer Experiences with Masculinity Attitude Trajectories at the Individual and Group Level in Adolescent and Young Adult Males

PubMed Central

Marcell, Arik V.; Eftim, Sorina E.; Sonenstein, Freya L.; Pleck, Joseph H.

2013-01-01

Data were drawn from 845 males in the National Survey of Adolescent Males who were initially aged 15–17, and followed-up 2.5 and 4.5 years later, to their early twenties. Mixed-effects regression models (MRM) and semiparametric trajectory analyses (STA) modeled patterns of change in masculinity attitudes at the individual and group levels, guided by gender intensification theory and cognitive-developmental theory. Overall, men’s masculinity attitudes became significantly less traditional between middle adolescence and early adulthood. In MRM analyses using time-varying covariates, maintaining paternal coresidence and continuing to have first sex in uncommitted heterosexual relationships were significantly associated with masculinity attitudes remaining relatively traditional. The STA modeling identified three distinct patterns of change in masculinity attitudes. A traditional-liberalizing trajectory of masculinity attitudes was most prevalent, followed by traditional-stable and nontraditional-stable trajectories. Implications for gender intensification and cognitive-developmental approaches to masculinity attitudes are discussed. PMID:24187483

Longitudinal models of reading achievement of students with learning disabilities and without disabilities.

PubMed

Sullivan, Amanda L; Kohli, Nidhi; Farnsworth, Elyse M; Sadeh, Shanna; Jones, Leila

2017-09-01

Accurate estimation of developmental trajectories can inform instruction and intervention. We compared the fit of linear, quadratic, and piecewise mixed-effects models of reading development among students with learning disabilities relative to their typically developing peers. We drew an analytic sample of 1,990 students from the nationally representative Early Childhood Longitudinal Study-Kindergarten Cohort of 1998, using reading achievement scores from kindergarten through eighth grade to estimate three models of students' reading growth. The piecewise mixed-effects models provided the best functional form of the students' reading trajectories as indicated by model fit indices. Results showed slightly different trajectories between students with learning disabilities and without disabilities, with varying but divergent rates of growth throughout elementary grades, as well as an increasing gap over time. These results highlight the need for additional research on appropriate methods for modeling reading trajectories and the implications for students' response to instruction. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Leidenfrost vapour layer moderation of the drag crisis and trajectories of superhydrophobic and hydrophilic spheres falling in water.

PubMed

Vakarelski, Ivan U; Chan, Derek Y C; Thoroddsen, Sigurdur T

2014-08-21

We investigate the dynamic effects of a Leidenfrost vapour layer sustained on the surface of heated steel spheres during free fall in water. We find that a stable vapour layer sustained on the textured superhydrophobic surface of spheres falling through 95 °C water can reduce the hydrodynamic drag by up to 75% and stabilize the sphere trajectory for the Reynolds number between 10(4) and 10(6), spanning the drag crisis in the absence of the vapour layer. For hydrophilic spheres under the same conditions, the transition to drag reduction and trajectory stability occurs abruptly at a temperature different from the static Leidenfrost point. The observed drag reduction effects are attributed to the disruption of the viscous boundary layer by the vapour layer whose thickness depends on the water temperature. Both the drag reduction and the trajectory stabilization effects are expected to have significant implications for development of sustainable vapour layer based technologies.

Trajectory Design to Mitigate Risk on the Transiting Exoplanet Survey Satellite (TESS) Mission

NASA Technical Reports Server (NTRS)

Dichmann, Donald

2016-01-01

The Transiting Exoplanet Survey Satellite (TESS) will employ a highly eccentric Earth orbit, in 2:1 lunar resonance, reached with a lunar flyby preceded by 3.5 phasing loops. The TESS mission has limited propellant and several orbit constraints. Based on analysis and simulation, we have designed the phasing loops to reduce delta-V and to mitigate risk due to maneuver execution errors. We have automated the trajectory design process and use distributed processing to generate and to optimize nominal trajectories, check constraint satisfaction, and finally model the effects of maneuver errors to identify trajectories that best meet the mission requirements.

Dual Sticky Hierarchical Dirichlet Process Hidden Markov Model and Its Application to Natural Language Description of Motions.

PubMed

Hu, Weiming; Tian, Guodong; Kang, Yongxin; Yuan, Chunfeng; Maybank, Stephen

2017-09-25

In this paper, a new nonparametric Bayesian model called the dual sticky hierarchical Dirichlet process hidden Markov model (HDP-HMM) is proposed for mining activities from a collection of time series data such as trajectories. All the time series data are clustered. Each cluster of time series data, corresponding to a motion pattern, is modeled by an HMM. Our model postulates a set of HMMs that share a common set of states (topics in an analogy with topic models for document processing), but have unique transition distributions. For the application to motion trajectory modeling, topics correspond to motion activities. The learnt topics are clustered into atomic activities which are assigned predicates. We propose a Bayesian inference method to decompose a given trajectory into a sequence of atomic activities. On combining the learnt sources and sinks, semantic motion regions, and the learnt sequence of atomic activities, the action represented by the trajectory can be described in natural language in as automatic a way as possible. The effectiveness of our dual sticky HDP-HMM is validated on several trajectory datasets. The effectiveness of the natural language descriptions for motions is demonstrated on the vehicle trajectories extracted from a traffic scene.

Diagnosis as a social determinant: the development of prosocial behaviour before and after an autism spectrum diagnosis.

PubMed

Russell, Ginny; Kelly, Susan E; Ford, Tamsin; Steer, Colin

2012-11-01

Jutel and Nettleton (2011) discuss diagnosis as not only a major classification tool for medicine but also an interactive social process that itself may have ramifications for health. Consideration of diagnosis as a social determinant of health outcomes led to the formulation of our research question: Can we detect a change in the development of prosocial symptoms before and after an Autism Spectrum Disorder (ASD) diagnosis? We examined the developmental trajectory of prosocial skills of children, as impairment in social skills is given as a core symptom for children with ASD. We used a validated scale measuring prosocial behaviour for a sample of 57 children where the measure was repeatedly recorded over ten years. We plotted the developmental trajectory of the prosocial trait in this sample who were enrolled in a longitudinal birth cohort study based in South West England. Multi-factorial fixed effect modelling suggests that the developmental trajectory of this measure of behaviour was not significantly altered by ASD diagnosis, or the consequences of diagnosis, either for better or worse. Further analysis was conducted on a subset of 33 of the children who had both pre-diagnosis and post-diagnosis information, and the same result obtained. The results indicate that prosocial behaviours may be resistant to typical 'treatments': provision of educational and specialist health services triggered by a clinical ASD diagnosis. The implications of this for considering diagnosis as a social determinant are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Relational vulnerabilities of incarcerated and reentry mothers: therapeutic implications.

PubMed

Few-Demo, April L; Arditti, Joyce A

2014-11-01

A qualitative study involving a follow-up interview with 10 incarcerated and reentry mothers in rural southwest and central Virginia was conducted to explore the influence that women's close relationships have on their reentry experiences with their families. The Vulnerability Conceptual Model (VCM) was used to sensitize an examination of how incarcerated and reentry mothers negotiate relational vulnerabilities in the context of varying situational vulnerability. Grounded theory analysis revealed three themes that characterized relational vulnerabilities. Given our focus on close relationships and the potential of the VCM to identify opportunities for resilience and vulnerability, we highlighted the influence of ambiguous and ambivalent relationships and unresolved loss and grief due to relationship dissolution or the death of a parent, sibling, child, or intimate partner in the reentry process. The data revealed two types of reentry mothers with divergent trajectories for social reintegration. Implications of these types for therapeutic treatment approaches for reentry women are discussed. © The Author(s) 2013.

Flash trajectory imaging of target 3D motion

NASA Astrophysics Data System (ADS)

Wang, Xinwei; Zhou, Yan; Fan, Songtao; He, Jun; Liu, Yuliang

2011-03-01

We present a flash trajectory imaging technique which can directly obtain target trajectory and realize non-contact measurement of motion parameters by range-gated imaging and time delay integration. Range-gated imaging gives the range of targets and realizes silhouette detection which can directly extract targets from complex background and decrease the complexity of moving target image processing. Time delay integration increases information of one single frame of image so that one can directly gain the moving trajectory. In this paper, we have studied the algorithm about flash trajectory imaging and performed initial experiments which successfully obtained the trajectory of a falling badminton. Our research demonstrates that flash trajectory imaging is an effective approach to imaging target trajectory and can give motion parameters of moving targets.

Atomoxetine in patients with ADHD: A clinical and pharmacological review of the onset, trajectory, duration of response and implications for patients.

PubMed

Clemow, David B; Bushe, Chris J

2015-12-01

This article reviews data providing new insight into the trajectory of response and maintenance of response of atomoxetine in the treatment of child and adult attention-deficit hyperactivity disorder (ADHD). This nonsystematic review includes: onset of action and duration of effect, response rate, effect size, time to optimal response and norepinephrine transporter blockade biomarker data. Atomoxetine can have an onset of action within 1-2 weeks of starting treatment, but there is an incrementally increasing response for up to 24 weeks or longer. Responder rates and effect sizes are similar to methylphenidate. Upon treatment discontinuation, relapse rates are lower than expected. In adults, 50% maintain their response for at least 6 months after stopping atomoxetine, following 6 months of treatment. Single-dose atomoxetine can provide 24-hour efficacy, despite a 5-hour plasma half-life. Hypotheses can be generated relating to neuroadaptive changes, to explain these findings. Atomoxetine has a trajectory of response that is incremental over a long period of time, with a greater than expected maintenance of response. This has implications for physician atomoxetine dosing and efficacy assessment, patient education and outcomes, and for clinical trial design and assessment of comparative efficacy with stimulant medications. © The Author(s) 2015.

Trajectories of Global Self-Worth in Adolescents with ADHD: Associations with Academic, Emotional, and Social Outcomes.

PubMed

Dvorsky, Melissa R; Langberg, Joshua M; Becker, Stephen P; Evans, Steven W

2018-05-01

Resilience models suggest that there are likely to be multiple trajectories of self-worth and that despite experiencing impairment, some youth with attention deficit/hyperactivity disorder (ADHD) may maintain a positive self-worth, which could buffer them against negative outcomes. The present study used a cohort-sequential longitudinal design to evaluate developmental trajectories of global self-worth in a sample of 324 middle-school-age adolescents (71% male) diagnosed with ADHD between ages 11 and 14 in predicting outcomes at age 15. Sex, medication status, and ADHD/oppositional defiant disorder symptom severity were included as covariates in the models. Using growth mixture modeling, 3 distinct self-worth trajectory groups were identified: (a) high and increasing (44.4% of participants), (b) moderate and decreasing (48.8%), and (c) low and decreasing (6.8%). Participants with high and increasing global self-worth were less likely to exhibit co-occurring depressive symptoms and had better social functioning and higher grades at age 15 relative to those in either decreasing trajectory. Implications of these findings for monitoring and supporting positive global self-worth for adolescents with ADHD are discussed.

An Extended Trajectory Mechanics Approach for Calculating the Path of a Pressure Transient: Derivation and Illustration

NASA Astrophysics Data System (ADS)

Vasco, D. W.

2018-04-01

Following an approach used in quantum dynamics, an exponential representation of the hydraulic head transforms the diffusion equation governing pressure propagation into an equivalent set of ordinary differential equations. Using a reservoir simulator to determine one set of dependent variables leaves a reduced set of equations for the path of a pressure transient. Unlike the current approach for computing the path of a transient, based on a high-frequency asymptotic solution, the trajectories resulting from this new formulation are valid for arbitrary spatial variations in aquifer properties. For a medium containing interfaces and layers with sharp boundaries, the trajectory mechanics approach produces paths that are compatible with travel time fields produced by a numerical simulator, while the asymptotic solution produces paths that bend too strongly into high permeability regions. The breakdown of the conventional asymptotic solution, due to the presence of sharp boundaries, has implications for model parameter sensitivity calculations and the solution of the inverse problem. For example, near an abrupt boundary, trajectories based on the asymptotic approach deviate significantly from regions of high sensitivity observed in numerical computations. In contrast, paths based on the new trajectory mechanics approach coincide with regions of maximum sensitivity to permeability changes.

Learning Careers/Learning Trajectories. Trends and Issues Alert.

ERIC Educational Resources Information Center

Kerka, Sandra

"Learning autobiography,""learning career," and "learning trajectory" are related descriptors for the process of developing attitudes toward learning and the origins of interests, learning styles, and learning processes. The learning career is composed of events, activities, and interpretations that develop individual…

Trajectory description of the quantum–classical transition for wave packet interference

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw

2016-08-15

The quantum–classical transition for wave packet interference is investigated using a hydrodynamic description. A nonlinear quantum–classical transition equation is obtained by introducing a degree of quantumness ranging from zero to one into the classical time-dependent Schrödinger equation. This equation provides a continuous description for the transition process of physical systems from purely quantum to purely classical regimes. In this study, the transition trajectory formalism is developed to provide a hydrodynamic description for the quantum–classical transition. The flow momentum of transition trajectories is defined by the gradient of the action function in the transition wave function and these trajectories follow themore » main features of the evolving probability density. Then, the transition trajectory formalism is employed to analyze the quantum–classical transition of wave packet interference. For the collision-like wave packet interference where the propagation velocity is faster than the spreading speed of the wave packet, the interference process remains collision-like for all the degree of quantumness. However, the interference features demonstrated by transition trajectories gradually disappear when the degree of quantumness approaches zero. For the diffraction-like wave packet interference, the interference process changes continuously from a diffraction-like to collision-like case when the degree of quantumness gradually decreases. This study provides an insightful trajectory interpretation for the quantum–classical transition of wave packet interference.« less

Trajectories of male sexual aggression from adolescence through college: A latent class growth analysis.

PubMed

Swartout, Kevin M; Swartout, Ashlyn G; Brennan, Carolyn L; White, Jacquelyn W

2015-01-01

Approximately 25% of male college students report engaging in some form of sexual coercion by the end of their fourth year of college. White and Smith (2004) found that negative childhood experiences-childhood sexual abuse, childhood physical abuse, and witnessing domestic violence-predicted sexual aggression perpetrated before college, but not during the subsequent college years, a puzzling finding in view of the reasonably consistent rates of sexual aggression from adolescence to the first 2 years of college. The current study takes a person-centered approach to sexual aggression in an attempt to resolve this discrepancy. We examined the possibility of cohesive subgroups of men in terms of their frequency of sexual aggression across the pre-college and college years. A series of latent class growth models were fit to an existing longitudinal dataset of sexual experiences collected across four time points-pre-college through year 3 of college. A four-trajectory model fit the data well, exhibiting significantly better fit than a three-trajectory model. The four trajectories are interpreted as men who perpetrate sexual aggression at (1) low (71.5% of the sample), (2) moderate (21.2%), (3) decreasing (4.2%), and (4) increasing (3.1%) frequencies across time. Negative childhood experiences predicted membership of the decreasing trajectory, relative to the low trajectory, but did not predict membership of the increasing trajectory, explaining the discrepancy uncovered by White and Smith. Implications for primary prevention of sexual aggression are discussed. © 2015 Wiley Periodicals, Inc.

A Pilot Exploration of Symptom Trajectories in Adolescents with Cancer during Chemotherapy

PubMed Central

Ameringer, Suzanne; Elswick, R. K.; Shockey, Debra P.; Dillon, Robyn

2012-01-01

Background Chemotherapy is frequently administered in repetitive cycles. Adolescents with cancer suffer from multiple symptoms related to chemotherapy but knowledge of symptom trajectories across a cycle is limited. Examining trajectories over a cycle may reveal key periods to manage symptoms. Objectives The aims of this pilot were to describe the trajectory of symptoms (pain, sleep, fatigue, appetite, nausea, fatigue) and biological and behavioral variables (anxiety, stress, hematologic function) across one cycle; and examine relationships between variables. Interventions/Methods Nine adolescents with cancer within six months of diagnosis participated. Data were collected by surveys, chart review, and biologic measures on days 1 and 2 of the cycle, one week later (nadir), and day 1 of the following cycle. To evaluate the trajectory, a simple random effects repeated measures analysis was computed. Results The significant trajectories were fatigue (P = 0.003), difficulty sleeping (P = 0.032), and nausea (P = 0.04). Most of the adolescents reported some anticipatory anxiety about receiving chemotherapy. Significant correlations between symptoms and biobehavioral variables included anticipatory anxiety and nausea (P = 0.86, P = 0.003), trait anxiety and fatigue (r = −0.82, P < 0.001), and stress and pain (r = 0.78, P = 0.039). Conclusions Multiple symptoms were experienced across the cycle. Three symptoms displayed significant trajectories indicating that patterns of symptoms may be anticipated. Implications for Practice Pilot findings suggest monitoring symptoms, stress and anxiety across a cycle is important, not only during chemotherapy administration, but also prior to being admitted for chemotherapy. PMID:22561919

Trajectory data analyses for pedestrian space-time activity study.

PubMed

Qi, Feng; Du, Fei

2013-02-25

It is well recognized that human movement in the spatial and temporal dimensions has direct influence on disease transmission(1-3). An infectious disease typically spreads via contact between infected and susceptible individuals in their overlapped activity spaces. Therefore, daily mobility-activity information can be used as an indicator to measure exposures to risk factors of infection. However, a major difficulty and thus the reason for paucity of studies of infectious disease transmission at the micro scale arise from the lack of detailed individual mobility data. Previously in transportation and tourism research detailed space-time activity data often relied on the time-space diary technique, which requires subjects to actively record their activities in time and space. This is highly demanding for the participants and collaboration from the participants greatly affects the quality of data(4). Modern technologies such as GPS and mobile communications have made possible the automatic collection of trajectory data. The data collected, however, is not ideal for modeling human space-time activities, limited by the accuracies of existing devices. There is also no readily available tool for efficient processing of the data for human behavior study. We present here a suite of methods and an integrated ArcGIS desktop-based visual interface for the pre-processing and spatiotemporal analyses of trajectory data. We provide examples of how such processing may be used to model human space-time activities, especially with error-rich pedestrian trajectory data, that could be useful in public health studies such as infectious disease transmission modeling. The procedure presented includes pre-processing, trajectory segmentation, activity space characterization, density estimation and visualization, and a few other exploratory analysis methods. Pre-processing is the cleaning of noisy raw trajectory data. We introduce an interactive visual pre-processing interface as well as an automatic module. Trajectory segmentation(5) involves the identification of indoor and outdoor parts from pre-processed space-time tracks. Again, both interactive visual segmentation and automatic segmentation are supported. Segmented space-time tracks are then analyzed to derive characteristics of one's activity space such as activity radius etc. Density estimation and visualization are used to examine large amount of trajectory data to model hot spots and interactions. We demonstrate both density surface mapping(6) and density volume rendering(7). We also include a couple of other exploratory data analyses (EDA) and visualizations tools, such as Google Earth animation support and connection analysis. The suite of analytical as well as visual methods presented in this paper may be applied to any trajectory data for space-time activity studies.

Developmental Trajectories for Children With Dyslexia and Low IQ Poor Readers

PubMed Central

2016-01-01

Reading difficulties are found in children with both high and low IQ and it is now clear that both groups exhibit difficulties in phonological processing. Here, we apply the developmental trajectories approach, a new methodology developed for studying language and cognitive impairments in developmental disorders, to both poor reader groups. The trajectory methodology enables identification of atypical versus delayed development in datasets gathered using group matching designs. Regarding the cognitive predictors of reading, which here are phonological awareness, phonological short-term memory (PSTM) and rapid automatized naming (RAN), the method showed that trajectories for the two groups diverged markedly. Children with dyslexia showed atypical development in phonological awareness, while low IQ poor readers showed developmental delay. Low IQ poor readers showed atypical PSTM and RAN development, but children with dyslexia showed developmental delay. These divergent trajectories may have important ramifications for supporting each type of poor reader, although all poor readers showed weakness in all areas. Regarding auditory processing, the developmental trajectories were very similar for the two poor reader groups. However, children with dyslexia demonstrated developmental delay for auditory discrimination of Duration, while the low IQ children showed atypical development on this measure. The data show that, regardless of IQ, poor readers have developmental trajectories that differ from typically developing children. The trajectories approach enables differences in trajectory classification to be identified across poor reader group, as well as specifying the individual nature of these trajectories. PMID:27110928

Exploring the Williams syndrome face-processing debate: the importance of building developmental trajectories.

PubMed

Karmiloff-Smith, Annette; Thomas, Michael; Annaz, Dagmara; Humphreys, Kate; Ewing, Sandra; Brace, Nicola; Duuren, Mike; Pike, Graham; Grice, Sarah; Campbell, Ruth

2004-10-01

Face processing in Williams syndrome (WS) has been a topic of heated debate over the past decade. Initial claims about a normally developing ('intact') face-processing module were challenged by data suggesting that individuals with WS used a different balance of cognitive processes from controls, even when their behavioural scores fell within the normal range. Measurement of evoked brain potentials also point to atypical processes. However, two recent studies have claimed that people with WS process faces exactly like normal controls. In this paper, we examine the details of this continuing debate on the basis of three new face-processing experiments. In particular, for two of our experiments we built task-specific full developmental trajectories from childhood to adolescence/adulthood and plotted the WS data on these trajectories. The first experiment used photos of real faces. While it revealed broadly equivalent accuracy across groups, the WS participants were worse at configural processing when faces were upright and less sensitive than controls to face inversion. In Experiment 2, measuring face processing in a storybook context, the face inversion effect emerged clearly in controls but only weakly in the WS developmental trajectory. Unlike the controls, the Benton Face Recognition Test and the Pattern Construction results were not correlated in WS, highlighting the different developmental patterns in the two groups. Again in contrast to the controls, Experiment 3 with schematic faces and non-face stimuli revealed a configural-processing deficit in WS both with respect to their chronological age (CA) and to their level of performance on the Benton. These findings point to both delay and deviance in WS face processing and illustrate how vital it is to build developmental trajectories for each specific task.

Trajectory Design Enhancements to Mitigate Risk for the Transiting Exoplanet Survey Satellite (TESS)

NASA Technical Reports Server (NTRS)

Dichmann, Donald; Parker, Joel; Nickel, Craig; Lutz, Stephen

2016-01-01

The Transiting Exoplanet Survey Satellite (TESS) will employ a highly eccentric Earth orbit, in 2:1 lunar resonance, which will be reached with a lunar flyby preceded by 3.5 phasing loops. The TESS mission has limited propellant and several constraints on the science orbit and on the phasing loops. Based on analysis and simulation, we have designed the phasing loops to reduce delta-V (DV) and to mitigate risk due to maneuver execution errors. We have automated the trajectory design process and use distributed processing to generate and optimal nominal trajectories; to check constraint satisfaction; and finally to model the effects of maneuver errors to identify trajectories that best meet the mission requirements.

Data Wrangling Within Different Astronomy Career Trajectories

NASA Astrophysics Data System (ADS)

Guillen, Reynal; Gu, D.; Holbrook, J.; Murillo, L.; Traweek, S.

2012-01-01

Five kinds of astronomers work with large data sets: cosmologists, data analysts, instrumentation people, observers, and numerical theorists. Each of these career trajectories can diverge and converge in and out of collaborations with each other and perform different kinds of work. Nonetheless, each group defines and wrangles data differently. This poster characterizes their different meanings of data, analytic skills, techniques, and technologies. It also identifies some sites and patterns of convergence. We plot these collaborative relationships in bi-partite graphs. These emergent characteristics of the astronomy workforce have implications for curricula, pedagogies, and the division of labor in research collaborations.

Indicators of distress in newly diagnosed breast cancer patients

PubMed Central

Lucidi, Fabio; Mallia, Luca; D’Aiuto, Massimiliano; Merluzzi, Thomas V.

2015-01-01

Background. The diagnosis, treatment, and long-term management of cancer can present individuals with a multitude of stressors at various points in that trajectory. Psychosocial distress may appear early in the diagnostic process and have negative effects on compliance with treatment and subsequent quality of life. Purpose. The aim of the study was to determine early-phase predictors of distress before any medical treatment. Method. Consistent with the goals of the study, 123 newly diagnosed breast cancer patients (20 to 74 years old) completed multiple indicators of knowledge about breast cancer management and treatment, attitudes toward cancer, social support, coping efficacy, and distress. Results. SEM analysis confirmed the hypothesized model. Age was negatively associated with the patient’s knowledge (β = − 0.22), which, in turn, was positively associated with both attitudes toward breast cancer (β = 0.39) and coping self-efficacy (β = 0.36). Self-efficacy was then directly related to psychological distress (β = − 0.68). Conclusions. These findings establish indicators of distress in patients early in the cancer trajectory. From a practical perspective, our results have implications for screening for distress and for the development of early interventions that may be followed by healthcare professionals to reduce psychological distress. PMID:26244115

Tunneling Time and Weak Measurement in Strong Field Ionization.

PubMed

Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R; Gordon, Daniel F; Landsman, Alexandra S

2016-06-10

Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process.

Mobile phone tracking: in support of modelling traffic-related air pollution contribution to individual exposure and its implications for public health impact assessment.

PubMed

Liu, Hai-Ying; Skjetne, Erik; Kobernus, Mike

2013-11-04

We propose a new approach to assess the impact of traffic-related air pollution on public health by mapping personal trajectories using mobile phone tracking technology in an urban environment. Although this approach is not based on any empirical studies, we believe that this method has great potential and deserves serious attention. Mobile phone tracking technology makes it feasible to generate millions of personal trajectories and thereby cover a large fraction of an urban population. Through analysis, personal trajectories are not only associated to persons, but it can also be associated with vehicles, vehicle type, vehicle speed, vehicle emission rates, and sources of vehicle emissions. Pollution levels can be estimated by dispersion models from calculated traffic emissions. Traffic pollution exposure to individuals can be estimated based on the exposure along the individual human trajectories in the estimated pollution concentration fields by utilizing modelling tools. By data integration, one may identify trajectory patterns of particularly exposed human groups. The approach of personal trajectories may open a new paradigm in understanding urban dynamics and new perspectives in population-wide empirical public health research. This new approach can be further applied to individual commuter route planning, land use planning, urban traffic network planning, and used by authorities to formulate air pollution mitigation policies and regulations.

Developmental Trajectories of Cigarette Smoking from Adolescence to the Early Thirties: Personality and Behavioral Risk Factors

PubMed Central

Brook, David W.; Brook, Judith S.; Zhang, Chenshu; Whiteman, Martin; Cohen, Patricia; Finch, Stephen J.

2013-01-01

The purpose of this study was to identify distinct trajectories of cigarette smoking from ages 14 to 32, and to examine adolescent personality factors that distinguish trajectories of smoking behavior. Participants (N=975) were randomly selected and followed prospectively since 1975. Follow-up data on cigarette use and personality and behavioral attributes were collected at five points in time, using structured interviews given in private by trained interviewers. Of these subjects, 746 comprised the cohort used in this study. Growth mixture modeling identified five smoking trajectory groups: nonsmokers, occasional smokers, late starters, quitters, and heavy/continuous smokers. Adolescent personality and behavioral risk factors such as lower ego integration, more externalizing behavior, and lower educational aspirations distinguished the trajectory groups. No gender differences were noted. The findings supported the hypotheses indicating multiple distinct trajectory groups of smoking behavior. Smoking behavior appeared in early adolescence and most often continued into adulthood. Emotional difficulties (i.e., lower ego integration), externalizing behavior, and lower educational aspirations in early adolescence were associated both with smoking at an early age and with continuing to smoke into the thirties. To be more effective, smoking prevention programs should target personality and behavioral variations, before smoking becomes habitual, particularly focused on characteristics reflecting behavioral problems as manifested in emotional difficulties, externalizing behavior, and low educational aspirations in early adolescence. The implications for research, prevention, and treatment are discussed. PMID:18686175

Mobile phone tracking: in support of modelling traffic-related air pollution contribution to individual exposure and its implications for public health impact assessment

PubMed Central

2013-01-01

We propose a new approach to assess the impact of traffic-related air pollution on public health by mapping personal trajectories using mobile phone tracking technology in an urban environment. Although this approach is not based on any empirical studies, we believe that this method has great potential and deserves serious attention. Mobile phone tracking technology makes it feasible to generate millions of personal trajectories and thereby cover a large fraction of an urban population. Through analysis, personal trajectories are not only associated to persons, but it can also be associated with vehicles, vehicle type, vehicle speed, vehicle emission rates, and sources of vehicle emissions. Pollution levels can be estimated by dispersion models from calculated traffic emissions. Traffic pollution exposure to individuals can be estimated based on the exposure along the individual human trajectories in the estimated pollution concentration fields by utilizing modelling tools. By data integration, one may identify trajectory patterns of particularly exposed human groups. The approach of personal trajectories may open a new paradigm in understanding urban dynamics and new perspectives in population-wide empirical public health research. This new approach can be further applied to individual commuter route planning, land use planning, urban traffic network planning, and used by authorities to formulate air pollution mitigation policies and regulations. PMID:24188173

Webinar Presentation: Exposures to Polycyclic Aromatic Hydrocarbons and Childhood Growth Trajectories and Body Composition: Linkages to Disrupted Self-Regulatory Processes

EPA Pesticide Factsheets

This presentation, Exposures to Polycyclic Aromatic Hydrocarbons and Childhood Growth Trajectories and Body Composition: Linkages to Disrupted Self-Regulatory Processes, was given at the NIEHS/EPA Children's Centers 2016 Webinar Series: Childhood Obesity

Generalized Poisson-Kac Processes: Basic Properties and Implications in Extended Thermodynamics and Transport

NASA Astrophysics Data System (ADS)

Giona, Massimiliano; Brasiello, Antonio; Crescitelli, Silvestro

2016-04-01

We introduce a new class of stochastic processes in Rn,{{{mathbb R}}^n}, referred to as generalized Poisson-Kac (GPK) processes, that generalizes the Poisson-Kac telegrapher's random motion in higher dimensions. These stochastic processes possess finite propagation velocity, almost everywhere smooth trajectories, and converge in the Kac limit to Brownian motion. GPK processes are defined by coupling the selection of a bounded velocity vector from a family of N distinct ones with a Markovian dynamics controlling probabilistically this selection. This model can be used as a probabilistic tool for a stochastically consistent formulation of extended thermodynamic theories far from equilibrium.

Rapid, Long-Distance Dispersal by Pumice Rafting

PubMed Central

Bryan, Scott E.; Cook, Alex G.; Evans, Jason P.; Hebden, Kerry; Hurrey, Lucy; Colls, Peter; Jell, John S.; Weatherley, Dion; Firn, Jennifer

2012-01-01

Pumice is an extremely effective rafting agent that can dramatically increase the dispersal range of a variety of marine organisms and connect isolated shallow marine and coastal ecosystems. Here we report on a significant recent pumice rafting and long-distance dispersal event that occurred across the southwest Pacific following the 2006 explosive eruption of Home Reef Volcano in Tonga. We have constrained the trajectory, and rate, biomass and biodiversity of transfer, discovering more than 80 species and a substantial biomass underwent a >5000 km journey in 7–8 months. Differing microenvironmental conditions on the pumice, caused by relative stability of clasts at the sea surface, promoted diversity in biotic recruitment. Our findings emphasise pumice rafting as an important process facilitating the distribution of marine life, which have implications for colonisation processes and success, the management of sensitive marine environments, and invasive pest species. PMID:22815770

Climate Change Implications to Vegetation Production in Alaska

NASA Technical Reports Server (NTRS)

Neigh, Christopher S.R.

2008-01-01

Investigation of long-term meteorological satellite data revealed statistically significant vegetation response to climate drivers of temperature, precipitation and solar radiation with exclusion of fire disturbance in Alaska. Abiotic trends were correlated to satellite remote sensing observations of normalized difference vegetation index to understand biophysical processes that could impact ecosystem carbon storage. Warming resulted in disparate trajectories for vegetation growth due to precipitation and photosynthetically active radiation variation. Interior spruce forest low lands in late summer through winter had precipitation deficit which resulted in extensive fire disturbance and browning of undisturbed vegetation with reduced post-fire recovery while Northern slope moist alpine tundra had increased production due to warmer-wetter conditions during the late 1990s and early 2000s. Coupled investigation of Alaska s vegetation response to warming climate found spatially dynamic abiotic processes with vegetation browning not a result from increased fire disturbance.

Reentry trajectory optimization based on a multistage pseudospectral method.

PubMed

Zhao, Jiang; Zhou, Rui; Jin, Xuelian

2014-01-01

Of the many direct numerical methods, the pseudospectral method serves as an effective tool to solve the reentry trajectory optimization for hypersonic vehicles. However, the traditional pseudospectral method is time-consuming due to large number of discretization points. For the purpose of autonomous and adaptive reentry guidance, the research herein presents a multistage trajectory control strategy based on the pseudospectral method, capable of dealing with the unexpected situations in reentry flight. The strategy typically includes two subproblems: the trajectory estimation and trajectory refining. In each processing stage, the proposed method generates a specified range of trajectory with the transition of the flight state. The full glide trajectory consists of several optimal trajectory sequences. The newly focused geographic constraints in actual flight are discussed thereafter. Numerical examples of free-space flight, target transition flight, and threat avoidance flight are used to show the feasible application of multistage pseudospectral method in reentry trajectory optimization.

Reentry Trajectory Optimization Based on a Multistage Pseudospectral Method

PubMed Central

Zhou, Rui; Jin, Xuelian

2014-01-01

Of the many direct numerical methods, the pseudospectral method serves as an effective tool to solve the reentry trajectory optimization for hypersonic vehicles. However, the traditional pseudospectral method is time-consuming due to large number of discretization points. For the purpose of autonomous and adaptive reentry guidance, the research herein presents a multistage trajectory control strategy based on the pseudospectral method, capable of dealing with the unexpected situations in reentry flight. The strategy typically includes two subproblems: the trajectory estimation and trajectory refining. In each processing stage, the proposed method generates a specified range of trajectory with the transition of the flight state. The full glide trajectory consists of several optimal trajectory sequences. The newly focused geographic constraints in actual flight are discussed thereafter. Numerical examples of free-space flight, target transition flight, and threat avoidance flight are used to show the feasible application of multistage pseudospectral method in reentry trajectory optimization. PMID:24574929

A stereoscopic imaging system for laser back scatter based trajectory measurement in ballistics: part 2

NASA Astrophysics Data System (ADS)

Chalupka, Uwe; Rothe, Hendrik

2012-03-01

The progress on a laser- and stereo-camera-based trajectory measurement system that we already proposed and described in recent publications is given. The system design was extended from one to two more powerful, DSP-controllable LASER systems. Experimental results of the extended system using different projectile-/weapon combinations will be shown and discussed. Automatic processing of acquired images using common 3DIP techniques was realized. Processing steps to extract trajectory segments from images as representative for the current application will be presented. Used algorithms for backward-calculation of the projectile trajectory will be shown. Verification of produced results is done against simulated trajectories, once in terms of detection robustness and once in terms of detection accuracy. Fields of use for the current system are within the ballistic domain. The first purpose is for trajectory measurement of small and middle caliber projectiles on a shooting range. Extension to big caliber projectiles as well as an application for sniper detection is imaginable, but would require further work. Beside classical RADAR, acoustic and optical projectile detection methods, the current system represents a further projectile location method under the new class of electro-optical methods that have been evolved in recent decades and that uses 3D imaging acquisition and processing techniques.

Milestoning with coarse memory

NASA Astrophysics Data System (ADS)

Hawk, Alexander T.

2013-04-01

Milestoning is a method used to calculate the kinetics of molecular processes occurring on timescales inaccessible to traditional molecular dynamics (MD) simulations. In the method, the phase space of the system is partitioned by milestones (hypersurfaces), trajectories are initialized on each milestone, and short MD simulations are performed to calculate transitions between neighboring milestones. Long trajectories of the system are then reconstructed with a semi-Markov process from the observed statistics of transition. The procedure is typically justified by the assumption that trajectories lose memory between crossing successive milestones. Here we present Milestoning with Coarse Memory (MCM), a generalization of Milestoning that relaxes the memory loss assumption of conventional Milestoning. In the method, milestones are defined and sample transitions are calculated in the standard Milestoning way. Then, after it is clear where trajectories sample milestones, the milestones are broken up into distinct neighborhoods (clusters), and each sample transition is associated with two clusters: the cluster containing the coordinates the trajectory was initialized in, and the cluster (on the terminal milestone) containing trajectory's final coordinates. Long trajectories of the system are then reconstructed with a semi-Markov process in an extended state space built from milestone and cluster indices. To test the method, we apply it to a process that is particularly ill suited for Milestoning: the dynamics of a polymer confined to a narrow cylinder. We show that Milestoning calculations of both the mean first passage time and the mean transit time of reversal—which occurs when the end-to-end vector reverses direction—are significantly improved when MCM is applied. Finally, we note the overhead of performing MCM on top of conventional Milestoning is negligible.

Gaussian Processes for Prediction of Homing Pigeon Flight Trajectories

NASA Astrophysics Data System (ADS)

Mann, Richard; Freeman, Robin; Osborne, Michael; Garnett, Roman; Meade, Jessica; Armstrong, Chris; Biro, Dora; Guilford, Tim; Roberts, Stephen

2009-12-01

We construct and apply a stochastic Gaussian Process (GP) model of flight trajectory generation for pigeons trained to home from specific release sites. The model shows increasing predictive power as the birds become familiar with the sites, mirroring the animal's learning process. We show how the increasing similarity between successive flight trajectories can be used to infer, with increasing accuracy, an idealised route that captures the repeated spatial aspects of the bird's flight. We subsequently use techniques associated with reduced-rank GP approximations to objectively identify the key waypoints used by each bird to memorise its idiosyncratic habitual route between the release site and the home loft.

Flight Evaluation of Center-TRACON Automation System Trajectory Prediction Process

NASA Technical Reports Server (NTRS)

Williams, David H.; Green, Steven M.

1998-01-01

Two flight experiments (Phase 1 in October 1992 and Phase 2 in September 1994) were conducted to evaluate the accuracy of the Center-TRACON Automation System (CTAS) trajectory prediction process. The Transport Systems Research Vehicle (TSRV) Boeing 737 based at Langley Research Center flew 57 arrival trajectories that included cruise and descent segments; at the same time, descent clearance advisories from CTAS were followed. Actual trajectories of the airplane were compared with the trajectories predicted by the CTAS trajectory synthesis algorithms and airplane Flight Management System (FMS). Trajectory prediction accuracy was evaluated over several levels of cockpit automation that ranged from a conventional cockpit to performance-based FMS vertical navigation (VNAV). Error sources and their magnitudes were identified and measured from the flight data. The major source of error during these tests was found to be the predicted winds aloft used by CTAS. The most significant effect related to flight guidance was the cross-track and turn-overshoot errors associated with conventional VOR guidance. FMS lateral navigation (LNAV) guidance significantly reduced both the cross-track and turn-overshoot error. Pilot procedures and VNAV guidance were found to significantly reduce the vertical profile errors associated with atmospheric and airplane performance model errors.

Analysis of Video-Based Microscopic Particle Trajectories Using Kalman Filtering

PubMed Central

Wu, Pei-Hsun; Agarwal, Ashutosh; Hess, Henry; Khargonekar, Pramod P.; Tseng, Yiider

2010-01-01

Abstract The fidelity of the trajectories obtained from video-based particle tracking determines the success of a variety of biophysical techniques, including in situ single cell particle tracking and in vitro motility assays. However, the image acquisition process is complicated by system noise, which causes positioning error in the trajectories derived from image analysis. Here, we explore the possibility of reducing the positioning error by the application of a Kalman filter, a powerful algorithm to estimate the state of a linear dynamic system from noisy measurements. We show that the optimal Kalman filter parameters can be determined in an appropriate experimental setting, and that the Kalman filter can markedly reduce the positioning error while retaining the intrinsic fluctuations of the dynamic process. We believe the Kalman filter can potentially serve as a powerful tool to infer a trajectory of ultra-high fidelity from noisy images, revealing the details of dynamic cellular processes. PMID:20550894

Kinetic constrained optimization of the golf swing hub path.

PubMed

Nesbit, Steven M; McGinnis, Ryan S

2014-12-01

This study details an optimization of the golf swing, where the hand path and club angular trajectories are manipulated. The optimization goal was to maximize club head velocity at impact within the interaction kinetic limitations (force, torque, work, and power) of the golfer as determined through the analysis of a typical swing using a two-dimensional dynamic model. The study was applied to four subjects with diverse swing capabilities and styles. It was determined that it is possible for all subjects to increase their club head velocity at impact within their respective kinetic limitations through combined modifications to their respective hand path and club angular trajectories. The manner of the modifications, the degree of velocity improvement, the amount of kinetic reduction, and the associated kinetic limitation quantities were subject dependent. By artificially minimizing selected kinetic inputs within the optimization algorithm, it was possible to identify swing trajectory characteristics that indicated relative kinetic weaknesses of a subject. Practical implications are offered based upon the findings of the study. Key PointsThe hand path trajectory is an important characteristic of the golf swing and greatly affects club head velocity and golfer/club energy transfer.It is possible to increase the energy transfer from the golfer to the club by modifying the hand path and swing trajectories without increasing the kinetic output demands on the golfer.It is possible to identify relative kinetic output strengths and weakness of a golfer through assessment of the hand path and swing trajectories.Increasing any one of the kinetic outputs of the golfer can potentially increase the club head velocity at impact.The hand path trajectory has important influences over the club swing trajectory.

Kinetic Constrained Optimization of the Golf Swing Hub Path

PubMed Central

Nesbit, Steven M.; McGinnis, Ryan S.

2014-01-01

This study details an optimization of the golf swing, where the hand path and club angular trajectories are manipulated. The optimization goal was to maximize club head velocity at impact within the interaction kinetic limitations (force, torque, work, and power) of the golfer as determined through the analysis of a typical swing using a two-dimensional dynamic model. The study was applied to four subjects with diverse swing capabilities and styles. It was determined that it is possible for all subjects to increase their club head velocity at impact within their respective kinetic limitations through combined modifications to their respective hand path and club angular trajectories. The manner of the modifications, the degree of velocity improvement, the amount of kinetic reduction, and the associated kinetic limitation quantities were subject dependent. By artificially minimizing selected kinetic inputs within the optimization algorithm, it was possible to identify swing trajectory characteristics that indicated relative kinetic weaknesses of a subject. Practical implications are offered based upon the findings of the study. Key Points The hand path trajectory is an important characteristic of the golf swing and greatly affects club head velocity and golfer/club energy transfer. It is possible to increase the energy transfer from the golfer to the club by modifying the hand path and swing trajectories without increasing the kinetic output demands on the golfer. It is possible to identify relative kinetic output strengths and weakness of a golfer through assessment of the hand path and swing trajectories. Increasing any one of the kinetic outputs of the golfer can potentially increase the club head velocity at impact. The hand path trajectory has important influences over the club swing trajectory. PMID:25435779

Space Shuttle Day-of-Launch Trajectory Design Operations

NASA Technical Reports Server (NTRS)

Harrington, Brian E.

2011-01-01

A top priority of any launch vehicle is to insert as much mass into the desired orbit as possible. This requirement must be traded against vehicle capability in terms of dynamic control, thermal constraints, and structural margins. The vehicle is certified to specific structural limits which will yield certain performance characteristics of mass to orbit. Some limits cannot be certified generically and must be checked with each mission design. The most sensitive limits require an assessment on the day-of-launch. To further minimize vehicle loads while maximizing vehicle performance, a day-of-launch trajectory can be designed. This design is optimized according to that day s wind and atmospheric conditions, which increase the probability of launch. The day-of-launch trajectory design and verification process is critical to the vehicle s safety. The Day-Of-Launch I-Load Update (DOLILU) is the process by which the National Aeronautics and Space Administration's (NASA) Space Shuttle Program tailors the vehicle steering commands to fit that day s environmental conditions and then rigorously verifies the integrated vehicle trajectory s loads, controls, and performance. This process has been successfully used for almost twenty years and shares many of the same elements with other launch vehicles that execute a day-of-launch trajectory design or day-of-launch trajectory verification. Weather balloon data is gathered at the launch site and transmitted to the Johnson Space Center s Mission Control. The vehicle s first stage trajectory is then adjusted to the measured wind and atmosphere data. The resultant trajectory must satisfy loads and controls constraints. Additionally, these assessments statistically protect for non-observed dispersions. One such dispersion is the change in the wind from the last measured balloon to launch time. This process is started in the hours before launch and is repeated several times as the launch count proceeds. Should the trajectory design not meet all constraint criteria, Shuttle would be No-Go for launch. This Shuttle methodology is very similar to other unmanned launch vehicles. By extension, this method would likely be employed for any future NASA launch vehicle. This paper will review the Shuttle s day-of-launch trajectory optimization and verification operations as an example of a more generic application of day-of-launch design and validation. With Shuttle s retirement, it is fitting to document the current state of this critical process and capture lessons learned to benefit current and future launch vehicle endeavors.

Distinct trajectories of positive and negative affect after colorectal cancer diagnosis.

PubMed

Ciere, Yvette; Janse, Moniek; Almansa, Josué; Visser, Annemieke; Sanderman, Robbert; Sprangers, Mirjam A G; Ranchor, Adelita V; Fleer, Joke

2017-06-01

Insight into trajectories of positive affect (PA) and negative affect (NA) across the cancer continuum may improve understanding of the nature of adjustment problems. The primary aim of this study was to identify subgroups of patients with distinct trajectories of PA and NA following diagnosis of colorectal cancer (CRC). Secondary to this aim, the co-occurrence between trajectories and their association with goal-related processes was explored. CRC patients (n = 186) completed questionnaires within 1 month, 7 months, and 18 months after diagnosis. Multilevel models were used to study the trajectory of PA and NA, as measured with the Positive and Negative Affect Schedule (PANAS). Four classes with distinct PA trajectories were identified: low (18.8%), increasing (6.7%), moderate (68.2%), and high (6.3%); 2 trajectories of NA emerged: low (36.3%) and moderate (63.7%). There was no significant association between PA and NA trajectory class probabilities. The average trajectory of PA covaried with levels of goal disturbance and goal reengagement over time, while the average NA trajectory covaried with goal disturbance and goal disengagement. Compared with the general population, our sample of cancer patients suffered from a lack of positive emotions, but not a high presence of negative emotions. About one fifth of patients reported low PA up to 18 months after diagnosis and may benefit from supportive care. Furthermore, the trajectory of PA was independent of that of NA and related with a distinct goal adjustment process (i.e., goal disengagement vs. goal reengagement). This finding indicates the need to tailor psychological care to the nature of the adjustment problem. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Numerical model describing optimization of fibres winding process on open and closed frame

NASA Astrophysics Data System (ADS)

Petrů, M.; Mlýnek, J.; Martinec, T.

2016-08-01

This article discusses a numerical model describing optimization of fibres winding process on open and closed frame. The quality production of said type of composite frame depends primarily on the correct winding of fibers on a polyurethane core. It is especially needed to ensure the correct angles of the fibers winding on the polyurethane core and the homogeneity of individual winding layers. The article describes mathematical model for use an industrial robot in filament winding and how to calculate the trajectory of the robot. When winding fibers on the polyurethane core which is fastened to the robot-end-effector so that during the winding process goes through a fibre-processing head on the basis of the suitably determined robot-end-effector trajectory. We use the described numerical model and matrix calculus to enumerate the trajectory of the robot-end-effector to determine the desired passage of the frame through the fibre-processing head. The calculation of the trajectory was programmed in the Delphi development environment. Relations of the numerical model are important for use a real solving of the passage of a polyurethane core through fibre-processing head.

Victimization and Violent Offending: An Assessment of the Victim-Offender Overlap Among Native American Adolescents and Young Adults

PubMed Central

Reingle, Jennifer M.; Maldonado-Molina, Mildred M.

2013-01-01

The purpose of this article is to evaluate the victim–offender overlap among a nationally representative sample of Native American adolescents and young adults. Data for this study were obtained from 338 Native American youth who participated in the National Longitudinal Study of Adolescent Health (Add Health) Waves I-IV. Group-based trajectory modeling was used to estimate trajectories of violence and victimization separately. Bivariate tests were used to assess the overlap between victimization and violent trajectory groups. Multinomial regression procedures were used to assess the predictors of victimization, offending, and the overlap category of both victimization and offending. Three trajectory groups were found for violence (nonviolent, escalators, and desistors) and victimization (nonvictim, decreasing victimization, and increasing victimization). We found substantial evidence of an overlap between victimization and offending among Native Americans, as 27.5% of the sample reported both victimization and offending. Those in the overlap group had greater number of risk factors present at baseline. These results suggest that the victim–offender overlap is present in Native American adolescents. Explanations and implications are discussed. PMID:24078778

Posttraumatic Stress Symptoms and Trajectories in Child Sexual Abuse Victims: An Analysis of Sex Differences Using the National Survey of Child and Adolescent Well-Being

PubMed Central

Koenen, Karestan C.; Jaffee, Sara R.

2011-01-01

Very few studies have prospectively examined sex differences in posttraumatic stress symptoms and symptom trajectories in youth victimized by childhood sexual abuse. This study addresses that question in a relatively large sample of children, drawn from the National Survey of Child and Adolescent Well-Being, who were between the ages of 8–16 years and who were reported to Child Protective Services for alleged sexual abuse. Sex differences were examined using t tests, logistic regression, and latent trajectory modeling. Results revealed that there were not sex differences in victims’ posttraumatic stress symptoms or trajectories. Whereas caseworkers substantiated girls’ abuse at higher rates than boys’ abuse and rated girls significantly higher than boys on level of harm, there were not sex differences in three more objective measures of abuse severity characteristics. Overall, higher caseworker ratings of harm predicted higher initial posttraumatic stress symptom levels, and substantiation status predicted shallower decreases in trauma symptoms over time. Implications for theory and intervention are discussed. PMID:19221872

Counseling Issues for Adult Women in Career Transition

ERIC Educational Resources Information Center

Ronzio, Cynthia R.

2012-01-01

This article addresses current psychosocial issues facing women in career transition and the implications of those issues for career counselors. Specifically, psychosocial developmental trajectories, the roles of family and relationships, the importance of underlying physical and mental health issues, and sociocultural and contextual stressors are…

Pre-Surgery Depression and Confidence to Manage Problems Predict Recovery Trajectories of Health and Wellbeing in the First Two Years following Colorectal Cancer: Results from the CREW Cohort Study

PubMed Central

Foster, Claire; Haviland, Joanne; Winter, Jane; Grimmett, Chloe; Chivers Seymour, Kim; Batehup, Lynn; Calman, Lynn; Corner, Jessica; Din, Amy; Fenlon, Deborah; May, Christine M.; Richardson, Alison; Smith, Peter W.

2016-01-01

Purpose This paper identifies predictors of recovery trajectories of quality of life (QoL), health status and personal wellbeing in the two years following colorectal cancer surgery. Methods 872 adults receiving curative intent surgery during November 2010 to March 2012. Questionnaires at baseline, 3, 9, 15, 24 months post-surgery assessed QoL, health status, wellbeing, confidence to manage illness-related problems (self-efficacy), social support, co-morbidities, socio-demographic, clinical and treatment characteristics. Group-based trajectory analyses identified distinct trajectories and predictors for QoL, health status and wellbeing. Results Four recovery trajectories were identified for each outcome. Groups 1 and 2 fared consistently well (scores above/within normal range); 70.5% of participants for QoL, 33.3% health status, 77.6% wellbeing. Group 3 had some problems (24.2% QoL, 59.3% health, 18.2% wellbeing); Group 4 fared consistently poorly (5.3% QoL, 7.4% health, 4.2% wellbeing). Higher pre-surgery depression and lower self-efficacy were significantly associated with poorer trajectories for all three outcomes after adjusting for other important predictors including disease characteristics, stoma, anxiety and social support. Conclusions Psychosocial factors including self-efficacy and depression before surgery predict recovery trajectories in QoL, health status and wellbeing following colorectal cancer treatment independent of treatment or disease characteristics. This has significant implications for colorectal cancer management as appropriate support may be improved by early intervention resulting in more positive recovery experiences. PMID:27171174

Trajectories of psychological distress after prison release: implications for mental health service need in ex-prisoners.

PubMed

Thomas, E G; Spittal, M J; Heffernan, E B; Taxman, F S; Alati, R; Kinner, S A

2016-02-01

Understanding individual-level changes in mental health status after prison release is crucial to providing targeted and effective mental health care to ex-prisoners. We aimed to describe trajectories of psychological distress following prison discharge and compare these trajectories with mental health service use in the community. The Kessler Psychological Distress Scale (K10) was administered to 1216 sentenced adult prisoners in Queensland, Australia, before prison release and approximately 1, 3 and 6 months after release. We used group-based trajectory modeling to identify K10 trajectories after release. Contact with community mental health services in the year following release was assessed via data linkage. We identified five trajectory groups, representing consistently low (51.1% of the cohort), consistently moderate (29.8%), high increasing (11.6%), high declining (5.5%) and consistently very high (1.9%) psychological distress. Mood disorder, anxiety disorder, history of self-harm and risky drug use were risk factors for the high increasing, very high and high declining trajectory groups. Women were over-represented in the high increasing and high declining groups, but men were at higher risk of very high psychological distress. Within the high increasing and very high groups, 25% of participants accessed community mental health services in the first year post-release, for a median of 4.4 contact hours. For the majority of prisoners with high to very high psychological distress, distress persists after release. However, contact with mental health services in the community appears low. Further research is required to understand barriers to mental health service access among ex-prisoners.

Initial Concept of Operations for Full Management by Trajectory

NASA Technical Reports Server (NTRS)

Fernandes, Alicia D.; Atkins, Steve; Leiden, Ken; Kaler, Curt; Evans, Mark; Bell, Alan; Kilbourne, Todd; Jackson, Michael

2017-01-01

This document describes Management by Trajectory (MBT), a concept for future air traffic management (ATM) in which flights are assigned four-dimensional trajectories (4DTs) through a negotiation process between the Federal Aviation Administration (FAA) and flight operators that respects the flight operator's goals while complying with National Airspace System (NAS) constraints.

Joint Trajectories of Behavioral, Affective, and Cognitive Engagement in Elementary School

ERIC Educational Resources Information Center

Archambault, Isabelle; Dupéré, Véronique

2017-01-01

The aim of the present study was to model student trajectories of behavioral, affective, and cognitive engagement from Grade 3 to Grade 6. The authors also examined whether teachers perceptions could predict student trajectory membership. The authors collected data from a sample of 831 students and 152 teachers. Using multiple-process growth…

Experimental investigation on underwater trajectory deviation of high-speed projectile with different nose shape

NASA Astrophysics Data System (ADS)

Zhang, Wei; Qi, Yafei; Huang, Wei; Gao, Yubo

2017-01-01

The investigation on free-surface impact of projectiles has last for more than one hundred years due to its noticeable significance on improving defensive weapon technology. Laboratory-scaled water entry experiments for trajectory stability had been performed with four kinds of projectiles at a speed range of 20˜200 m/s. The nose shapes of the cylindrical projectiles were designed into flat, ogive, hemi-sphere and cone to make comparisons on the trajectory deviation when they were launched into water at a certain angle of 0˜20°. Two high-speed cameras positioned orthogonal to each other and normal to the water tank were employed to capture the entire process of projectiles' penetration. From the experimental results, the consecutive images in two planes were presented to display the general process of the trajectory deviation. Compared with the effect of impact velocities and nose shape on trajectory deviation, it merited conclude that flat projectiles had a better trajectory stability, while ogival projectiles experienced the largest attitude change. The characteristics of pressure waves were also investigated.

Welding torch trajectory generation for hull joining using autonomous welding mobile robot

NASA Astrophysics Data System (ADS)

Hascoet, J. Y.; Hamilton, K.; Carabin, G.; Rauch, M.; Alonso, M.; Ares, E.

2012-04-01

Shipbuilding processes involve highly dangerous manual welding operations. Welding of ship hulls presents a hazardous environment for workers. This paper describes a new robotic system, developed by the SHIPWELD consortium, that moves autonomously on the hull and automatically executes the required welding processes. Specific focus is placed on the trajectory control of such a system and forms the basis for the discussion in this paper. It includes a description of the robotic hardware design as well as some methodology used to establish the torch trajectory control.

Trajectories of fathers' psychological distress across the early parenting period: Implications for parenting.

PubMed

Giallo, Rebecca; Cooklin, Amanda; Brown, Stephanie; Christensen, Daniel; Kingston, Dawn; Liu, Cindy H; Wade, Catherine; Nicholson, Jan M

2015-10-01

Fathers' parenting behavior is a likely key mechanism underlying the consistent associations between paternal mental health difficulties and poor emotional-behavioral outcomes for children. This study investigates the association between fathers' mental health trajectories and key parenting behaviors (warmth, hostility, consistency) spanning the first 8-9 years postpartum. Secondary analyses of 5 waves of data from 2,662 fathers participating in the Longitudinal Study of Australian Children were conducted. Latent growth class analysis was used to identify distinct trajectories of fathers' distress (Kessler-6; Kessler et al., 2003), and latent growth models estimated parenting warmth, hostility, and consistency. Multiple group analyses were conducted to describe and compare the course of parenting behaviors for fathers assigned to the distress trajectories identified. Two distinct classes of fathers were identified based on the trajectories of distress: minimal distress (92%) and persistent and increasing distress (8%). The latter group reported significantly lower parenting warmth when their children were 8-9 years and lower consistency and higher hostility across all study intervals. The postnatal and early parenting period is a critical time for the development of parenting behaviors that are important for children's development. Engagement and support for fathers around well-being and parenting is vital for promoting optimal family and child developmental outcomes. (c) 2015 APA, all rights reserved).

Body Mass Trajectories and Mortality Among Older Adults: A Joint Growth Mixture–Discrete-Time Survival Analysis

PubMed Central

Zajacova, Anna

2014-01-01

Purpose of the Study: The aim of this study was to investigate heterogeneity in body weight trajectories among older adults and their association with mortality risks. Design and Methods: Information on body mass index (BMI) and survival come from nine waves of the Health and Retirement Study, a 16-year survey of adults aged 51–61 at baseline (N = 9,703). We used a sex-stratified joint growth mixture-discrete time survival model to characterize BMI trajectory groups and their associated mortality. Results: Three distinct classes of BMI trajectories were identified: “stable overweight,” “obese gaining,” and “obese losing.” Relative to the stable overweight class, which comprised about 90% of the sample, the obese gaining class had approximately 50% higher mortality risk; the highest mortality was found in the obese losing category (OR > 2.7, p < .001). The results were similar for men and women. Implications: The findings highlight substantial heterogeneity in weight trajectories of older Americans, as well as large survival differentials across the classes. The direction of weight changes appears inextricably linked to the overall BMI level in terms of predicting older adults’ longevity. Weight loss is associated with particularly high mortality risk even when the typical BMI change is from obesity to overweight. PMID:23355450

Satellite Broadband Revolution: How Latest Ka-Band Systems Will Change the Rules of the Industry. An Interpretation of the Technological Trajectory

NASA Astrophysics Data System (ADS)

Valle, Fabio

The paper analyzes the satellite broadband systems for consumer from the perspective of technological innovation. The suggested interpretation relies upon such concepts as technological paradigm, technological trajectory and salient points. Satellite technology for broadband is a complex system on which each component (i.e. the satellite, the end-user equipment, the on-ground systems and related infrastructure) develops at different speed. Innovation in this industry concentrates recently on satellite space aircraft that seemed to be the component with the highest perceived opportunity for improvement. The industry has designed recently satellite systems with continuous dimensional increase of capacity available, suggesting that there is a technological trajectory in this area, similar to Moore’s law in the computer industry. The implications for industry players, Ka-band systems, and growth of future applications are also examined.

End-to-End Trajectory for Conjunction Class Mars Missions Using Hybrid Solar-Electric/Chemical Transportation System

NASA Technical Reports Server (NTRS)

Chai, Patrick R.; Merrill, Raymond G.; Qu, Min

2016-01-01

NASA's Human Spaceflight Architecture Team is developing a reusable hybrid transportation architecture in which both chemical and solar-electric propulsion systems are used to deliver crew and cargo to exploration destinations. By combining chemical and solar-electric propulsion into a single spacecraft and applying each where it is most effective, the hybrid architecture enables a series of Mars trajectories that are more fuel efficient than an all chemical propulsion architecture without significant increases to trip time. The architecture calls for the aggregation of exploration assets in cislunar space prior to departure for Mars and utilizes high energy lunar-distant high Earth orbits for the final staging prior to departure. This paper presents the detailed analysis of various cislunar operations for the EMC Hybrid architecture as well as the result of the higher fidelity end-to-end trajectory analysis to understand the implications of the design choices on the Mars exploration campaign.

Developmental trajectories of writing skills in first grade: Examining the effects of SES and language and/or speech impairments

PubMed Central

Kim, Young-Suk; Puranik, Cynthia; Otaiba, Stephanie Al

2013-01-01

We examined growth trajectories of writing and the relation of children's socio-economic status, and language and/or speech impairment to the growth trajectories. First grade children (N = 304) were assessed on their written composition in the fall, winter, and spring, and their vocabulary and literacy skills in the fall. Children's SES had a negative effect on writing quality and productivity. Children with language and/or speech impairment had lower scores than typically developing children in the quality and productivity of writing. Even after accounting for their vocabulary and literacy skills, students with language and/or speech impairment had lower scores in the quality and organization of writing. Growth rates in writing were not different as a function of children's SES and language/speech impairment status. Theoretical and practical implications are discussed. PMID:26146410

Dual Trajectories of Depression/Anxiety Symptoms and Alcohol Use, and their Implications for Violence Outcomes Among Drug-Using Urban Youth.

PubMed

Goldstick, Jason E; Bohnert, Kipling M; Davis, Alan K; Bonar, Erin E; Carter, Patrick M; Walton, Maureen A; Cunningham, Rebecca M

2018-05-26

To examine dual trajectories of anxiety/depression symptoms and alcohol use among drug-using youth seeking care from an urban emergency department (ED), their baseline correlates and co-occurring trajectories of severe violence. There were five characteristic dual trajectories of alcohol use and depression/anxiety symptoms. Community violence exposure was highest among individuals with high-depression/anxiety symptom trajectories. Individuals with concurrently high-alcohol use and depression/anxiety symptom trajectories reported that the most delinquent peer affiliations, and had the highest rates of severe violence over time. We analyzed data from 599 drug-using (primarily marijuana) youth ages 14-24 (349 assault-injured) recruited from December 2009 to September 2011 into a 24-month longitudinal study at a Level-1 ED in Flint, Michigan. Youth self-reported substance use, depression and anxiety symptoms, peer/parental behaviors, and severe violence involvement at baseline and four biannual follow-up assessments. Bivariate latent trajectory models identified homogeneous groups with similar trajectories on alcohol use and anxiety/depression symptoms; we compared baseline characteristics of each trajectory group and concurrent trajectories of severe violence (victimization and aggression). Our model identified five trajectory groups: Low drinking/No symptoms (LN; 10.4%; n = 62), No drinking/Moderate symptoms (NM; 15.7%; n = 94), Low drinking/Moderate symptoms (LM; 30.2%; n = 181), Low drinking/High symptoms (LH; 16.4%; n = 98) and High drinking/High symptoms (HH; 27.5%; n = 164). The HH group was characterized by more delinquent peer associations, and rates of community violence were higher among the high symptom groups. The HH group had the highest severe violence perpetration and victimization rates across time points; the LH group had similar violence rates to the LM and NM groups and the LN group had the lowest violence rates across time. Among drug-using youth, alcohol use interventions could benefit from a focus on peer influences, and those with a joint focus on violence involvement may be improved via inclusion of content related to mental health and community violence exposure.

Correlated motion of protein subdomains and large-scale conformational flexibility of RecA protein filament

NASA Astrophysics Data System (ADS)

Yu, Garmay; A, Shvetsov; D, Karelov; D, Lebedev; A, Radulescu; M, Petukhov; V, Isaev-Ivanov

2012-02-01

Based on X-ray crystallographic data available at Protein Data Bank, we have built molecular dynamics (MD) models of homologous recombinases RecA from E. coli and D. radiodurans. Functional form of RecA enzyme, which is known to be a long helical filament, was approximated by a trimer, simulated in periodic water box. The MD trajectories were analyzed in terms of large-scale conformational motions that could be detectable by neutron and X-ray scattering techniques. The analysis revealed that large-scale RecA monomer dynamics can be described in terms of relative motions of 7 subdomains. Motion of C-terminal domain was the major contributor to the overall dynamics of protein. Principal component analysis (PCA) of the MD trajectories in the atom coordinate space showed that rotation of C-domain is correlated with the conformational changes in the central domain and N-terminal domain, that forms the monomer-monomer interface. Thus, even though C-terminal domain is relatively far from the interface, its orientation is correlated with large-scale filament conformation. PCA of the trajectories in the main chain dihedral angle coordinate space implicates a co-existence of a several different large-scale conformations of the modeled trimer. In order to clarify the relationship of independent domain orientation with large-scale filament conformation, we have performed analysis of independent domain motion and its implications on the filament geometry.

Linking Childhood and Adult Criminality: Using a Life Course Framework to Examine Childhood Abuse and Neglect, Substance Use and Adult Partner Violence

PubMed Central

Minh, Anita; Matheson, Flora I.; Daoud, Nihaya; Hamilton-Wright, Sarah; Pedersen, Cheryl; Borenstein, Heidi; O’Campo, Patricia

2013-01-01

Child abuse and neglect, considered criminal acts under the Criminal Code of Canada, play an important role in substance use, violence, and other criminal behaviour in adulthood. We adopted the life course perspective to identify modifiable contextual influences and co-occurring individual, social, and familial determinants associated with adult criminality. Using in-depth interview data, a sub-sample of 13 women who had recently experienced intimate partner violence, recounted their experiences of childhood abuse, their own substance use or criminality, as well as implications of these factors on their children’s life trajectories. For the purposes of this paper criminality was defined as child abuse and neglect, domestic violence, illegal substance use and underage alcohol use. Our objective was to explore, in our data: (1) patterns and trajectories of criminality from childhood to adulthood among women who were victims of violence, and (2) cumulative effects of early life exposures on experiences of criminality; with the aim of describing the life course perspective as a useful framework to understand criminality along the life trajectory. The analysis was not designed to demonstrate causal connections between early childhood and adulthood experiences of criminality. Rather we generated qualitative and quantitative hypotheses to guide future research in the field. Implications for research and interventions are discussed. PMID:24169410

Trajectories of age-related cognitive decline and potential associated factors of cognitive function in senior citizens of Beijing.

PubMed

Li, He; Lv, Chenlong; Zhang, Ting; Chen, Kewei; Chen, Chuansheng; Gai, Guozhong; Hu, Liangping; Wang, Yongyan; Zhang, Zhanjun

2014-01-01

With a longer life expectancy and an increased prevalence of neurodegenerative diseases, investigations on trajectories of cognitive aging have become exciting and promising. This study aimed to estimate the patterns of age-related cognitive decline and the potential associated factors of cognitive function in community-dwelling residents of Beijing, China. In this study, 1248 older adults aged 52-88 years [including 175 mild cognitive impairment (MCI) subjects] completed a battery of neuropsychological scales. The personal information, including demographic information, medical history, eating habits, lifestyle regularity and leisure activities, was also collected. All cognitive function exhibited an agerelated decline in normal volunteers. Piece-wise linear fitting results suggested that performance on the Auditory Verbal Learning Test remained stable until 58 years of age and continued to decline thereafter. The decline in processing speed and executive function began during the early 50's. Scores on visual-spatial and language tests declined after 66 years of age. The decline stage of the general mental status ranged from 63 to 70 years of age. However, the MCI group did not exhibit an obvious age-related decline in most cognitive tests. Multivariate linear regression analyses indicated that education, gender, leisure activities, diabetes and eating habits were associated with cognitive abilities. These results indicated various trajectories of age-related decline across multiple cognitive domains. We also found different patterns of agerelated cognitive decline between MCI and normal elderly. These findings could help improve the guidance of cognitive intervention program and have implications for public policy issues.

Developmental trajectories of children's symbolic numerical magnitude processing skills and associated cognitive competencies.

PubMed

Vanbinst, Kiran; Ceulemans, Eva; Peters, Lien; Ghesquière, Pol; De Smedt, Bert

2018-02-01

Although symbolic numerical magnitude processing skills are key for learning arithmetic, their developmental trajectories remain unknown. Therefore, we delineated during the first 3years of primary education (5-8years of age) groups with distinguishable developmental trajectories of symbolic numerical magnitude processing skills using a model-based clustering approach. Three clusters were identified and were labeled as inaccurate, accurate but slow, and accurate and fast. The clusters did not differ in age, sex, socioeconomic status, or IQ. We also tested whether these clusters differed in domain-specific (nonsymbolic magnitude processing and digit identification) and domain-general (visuospatial short-term memory, verbal working memory, and processing speed) cognitive competencies that might contribute to children's ability to (efficiently) process the numerical meaning of Arabic numerical symbols. We observed minor differences between clusters in these cognitive competencies except for verbal working memory for which no differences were observed. Follow-up analyses further revealed that the above-mentioned cognitive competencies did not merely account for the cluster differences in children's development of symbolic numerical magnitude processing skills, suggesting that other factors account for these individual differences. On the other hand, the three trajectories of symbolic numerical magnitude processing revealed remarkable and stable differences in children's arithmetic fact retrieval, which stresses the importance of symbolic numerical magnitude processing for learning arithmetic. Copyright © 2017 Elsevier Inc. All rights reserved.

Method of particle trajectory recognition in particle flows of high particle concentration using a candidate trajectory tree process with variable search areas

DOEpatents

Shaffer, Franklin D.

2013-03-12

The application relates to particle trajectory recognition from a Centroid Population comprised of Centroids having an (x, y, t) or (x, y, f) coordinate. The method is applicable to visualization and measurement of particle flow fields of high particle. In one embodiment, the centroids are generated from particle images recorded on camera frames. The application encompasses digital computer systems and distribution mediums implementing the method disclosed and is particularly applicable to recognizing trajectories of particles in particle flows of high particle concentration. The method accomplishes trajectory recognition by forming Candidate Trajectory Trees and repeated searches at varying Search Velocities, such that initial search areas are set to a minimum size in order to recognize only the slowest, least accelerating particles which produce higher local concentrations. When a trajectory is recognized, the centroids in that trajectory are removed from consideration in future searches.

A Study of the Ozone Formation by Ensemble Back Trajectory-process Analysis Using the Eta-CMAQ Forecast Model over the Northeastern U.S. During the 2004 ICARTT Period

EPA Science Inventory

The integrated process rates (IPR) estimated by the Eta-CMAQ model at grid cells along the trajectory of the air mass transport path were analyzed to quantitatively investigate the relative importance of physical and chemical processes for O₃ formation and evolution ov...

TRAJECTORIES OF SUBSTANCE USE FREQUENCY AMONG ADOLESCENTS SEEN IN PRIMARY CARE: IMPLICATIONS FOR SCREENING

PubMed Central

Hadland, Scott E.; Copelas, Sarah H.; Harris, Sion K.

2017-01-01

Objective Anticipating how adolescents’ substance use may escalate is critical for primary care clinicians. We identified trajectories of use in a prospective cohort of adolescent primary care patients one year after a clinic visit. Study Design We recruited 12- to 18-year-olds from 9 New England practices between 2005–2008 and identified 5 trajectories of substance use. We first distinguished adolescents with no past-year use at a baseline clinic visit and at 12-month follow-up (trajectory A). For adolescents who used substances, we assessed past-90-day use at both timepoints, and identified the remaining 4 trajectories based on frequency of use. Trajectories included:

Quantifying long-term trajectories of plant community change with movement models: implication for ecological resilience

USDA-ARS?s Scientific Manuscript database

Quantification of rates and patterns of community dynamics is central for understanding the organization and function of ecosystems. These insights may support a greater empirical understanding of ecological resilience, and the application of resilience concepts toward ecosystem management. Distinct...

Neuropsychology of Child Maltreatment and Implications for School Psychologists

ERIC Educational Resources Information Center

Davis, Andrew S.; Moss, Lauren E.; Nogin, Margarita M.; Webb, Nadia Elizabeth

2015-01-01

Child maltreatment has the potential to alter a child's neurodevelopmental trajectory and substantially increase the risk of later psychiatric disorders, as well as to deleteriously impact neurocognitive functioning throughout the lifespan. Child maltreatment has been linked to multiple domains of neurocognitive impairment, including…

Ballistic projectile trajectory determining system

DOEpatents

Karr, Thomas J.

1997-01-01

A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile.

Knee joint kinematics and kinetics during the hop and cut after soft tissue artifact suppression: Time to reconsider ACL injury mechanisms?

PubMed

Smale, Kenneth B; Potvin, Brigitte M; Shourijeh, Mohammad S; Benoit, Daniel L

2017-09-06

The recent development of a soft tissue artifact (STA) suppression method allows us to re-evaluate the tibiofemoral kinematics currently linked to non-contact knee injuries. The purpose of this study was therefore to evaluate knee joint kinematics and kinetics in six degrees of freedom (DoF) during the loading phases of a jump lunge and side cut using this in silico method. Thirty-five healthy adults completed these movements and their surface marker trajectories were then scaled and processed with OpenSim's inverse kinematics (IK) and inverse dynamics tools. Knee flexion angle-dependent kinematic constraints defined based on previous bone pin (BP) marker trajectories were then applied to the OpenSim model during IK and these constrained results were then processed with the standard inverse dynamics tool. Significant differences for all hip, knee, and ankle DoF were observed after STA suppression for both the jump lunge and side cut. Using clinically relevant effect size estimates, we conclude that STA contamination had led to misclassifications in hip transverse plane angles, knee frontal and transverse plane angles, medial/lateral and distractive/compressive knee translations, and knee frontal plane moments between the NoBP and the BP IK solutions. Our results have substantial clinical implications since past research has used joint kinematics and kinetics contaminated by STA to identify risk factors for musculoskeletal injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determining individual variation in growth and its implication for life-history and population processes using the empirical Bayes method.

PubMed

Vincenzi, Simone; Mangel, Marc; Crivelli, Alain J; Munch, Stephan; Skaug, Hans J

2014-09-01

The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups) determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth) and L∞ (asymptotic size). Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC), the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish.

Anterior Cortical Development During Adolescence in Bipolar Disorder

PubMed Central

Najt, Pablo; Wang, Fei; Spencer, Linda; Johnston, Jennifer A.Y.; Cox Lippard, Elizabeth T.; Pittman, Brian P.; Lacadie, Cheryl; Staib, Lawrence H.; Papademetris, Xenophon; Blumberg, Hilary P.

2015-01-01

Background Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescence as a critical period in its development. Developmental abnormalities of anterior paralimbic and heteromodal frontal cortices, key structures in emotional regulation processes and central in BD, are implicated. However, few longitudinal studies have been conducted, limiting understanding of trajectory alterations in BD. In this study, we performed longitudinal neuroimaging of adolescents with and without BD and assessed volume changes over time, including changes in tissue overall and within gray and white matter. Larger decreases over time in anterior cortical volumes in the adolescents with BD were hypothesized. Gray matter decreases and white matter increases are typically observed during adolescence in anterior cortices. It was hypothesized that volume decreases over time in BD would reflect alterations in those processes, showing larger gray matter contraction and decreased white matter expansion. Methods Two high-resolution magnetic resonance imaging scans were obtained approximately two-years apart for 35 adolescents with BDI and 37 healthy adolescents. Differences over time between groups were investigated for volume overall and specifically for gray and white matter. Results Relative to healthy adolescents, adolescents with BDI showed greater volume contraction over time in a region including insula, and orbitofrontal, rostral and dorsolateral prefrontal cortices (P<.05, corrected), including greater gray matter contraction and decreased white matter expansion over time, in the BD compared to the healthy group. Conclusions: The findings support neurodevelopmental abnormalities during adolescence in BDI in anterior cortices, include altered developmental trajectories of anterior gray and white matter. PMID:26033826

How to test for partially predictable chaos.

PubMed

Wernecke, Hendrik; Sándor, Bulcsú; Gros, Claudius

2017-04-24

For a chaotic system pairs of initially close-by trajectories become eventually fully uncorrelated on the attracting set. This process of decorrelation can split into an initial exponential decrease and a subsequent diffusive process on the chaotic attractor causing the final loss of predictability. Both processes can be either of the same or of very different time scales. In the latter case the two trajectories linger within a finite but small distance (with respect to the overall extent of the attractor) for exceedingly long times and remain partially predictable. Standard tests for chaos widely use inter-orbital correlations as an indicator. However, testing partially predictable chaos yields mostly ambiguous results, as this type of chaos is characterized by attractors of fractally broadened braids. For a resolution we introduce a novel 0-1 indicator for chaos based on the cross-distance scaling of pairs of initially close trajectories. This test robustly discriminates chaos, including partially predictable chaos, from laminar flow. Additionally using the finite time cross-correlation of pairs of initially close trajectories, we are able to identify laminar flow as well as strong and partially predictable chaos in a 0-1 manner solely from the properties of pairs of trajectories.

Computational Study on Full-length Human Ku70 with Double Stranded DNA: Dynamics, Interactions and Functional Implications

NASA Technical Reports Server (NTRS)

Hu, Shaowen; Cucinotta, Francis A.

2009-01-01

The Ku70/80 heterodimer is the first repair protein in the initial binding of double-strand break (DSB) ends following DNA damage, and is a component of nonhomologous end joining repair, the primary pathway for DSB repair in mammalian cells. In this study we constructed a full-length human Ku70 structure based on its crystal structure, and performed 20 ns conventional molecular dynamic (CMD) simulations on this protein and several other complexes with short DNA duplexes of different sequences. The trajectories of these simulations indicated that, without the topological support of Ku80, the residues in the bridge and C-terminal arm of Ku70 are more flexible than other experimentally identified domains. We studied the two missing loops in the crystal structure and predicted that they are also very flexible. Simulations revealed that they make an important contribution to the Ku70 interaction with DNA. Dislocation of the previously studied SAP domain was observed in several systems, implying its role in DNA binding. Targeted molecular dynamic (TMD) simulation was also performed for one system with a far-away 14bp DNA duplex. The TMD trajectory and energetic analysis disclosed detailed interactions of the DNA-binding residues during the DNA dislocation, and revealed a possible conformational transition for a DSB end when encountering Ku70 in solution. Compared to experimentally based analysis, this study identified more detailed interactions between DNA and Ku70. Free energy analysis indicated Ku70 alone is able to bind DNA with relatively high affinity, with consistent contributions from various domains of Ku70 in different systems. The functional implications of these domains in the processes of Ku heterodimerization and DNA damage recognition and repair can be characterized in detail based upon this analysis.

The role of social position and depressive symptoms in adolescence for life-course trajectories of education and work: a cohort study.

PubMed

Landstedt, Evelina; Brydsten, Anna; Hammarström, Anne; Virtanen, Pekka; Almquist, Ylva B

2016-11-18

While a vast amount of studies confirm the social reproduction of class and status from one generation to the next, less is known about the role of health in the child generation for these processes. Research has shown that particularly mental distress in adolescence is important for future life chances. This study aimed to examine the importance of parental socioeconomic position and depressive symptoms in youth for life-course trajectories of education and labour market attachment among men and women. Based on four waves of questionnaire data from the Northern Swedish Cohort (n = 1,001), consisting of individuals born in 1965, three steps of gender-separate analyses were undertaken. First, the individual trajectories of education and labour market attachment from age 18 to 42 were mapped through sequence analysis. Second, cluster analysis was used to identify typical trajectories. Third, two indicators of parental socioeconomic position - occupational class and employment status - and depressive symptoms at age 16 were used in multinomial regression analyses to predict adult life-course trajectories. Four typical trajectories were identified for men, of which three were characterised by stable employment and various lengths of education, and the fourth reflected a more unstable situation. Among women, five trajectories emerged, characterised by more instability compared to men. Low parental occupational class and unemployment were significantly associated with a higher risk of ending up in less advantaged trajectories for men while, for women, this was only the case for occupational class. Youth levels of depressive symptoms did not significantly differ across the trajectories. This study found support for the intergenerational reproduction of social position, particularly when measured in terms of parental occupational class. Youth depressive symptoms did not show clear differences across types of trajectories, subsequently impeding such symptoms to trigger any selection processes. While this could be a consequence of the specific framework of the current study, it may also suggest that depressive symptoms in youth are not a root cause for the more complex processes through which how social position develops across life. The possible impact of welfare and labour market policies is discussed.

Detection of Diffusion Heterogeneity in Single Particle Tracking Trajectories Using a Hidden Markov Model with Measurement Noise Propagation

PubMed Central

Slator, Paddy J.; Cairo, Christopher W.; Burroughs, Nigel J.

2015-01-01

We develop a Bayesian analysis framework to detect heterogeneity in the diffusive behaviour of single particle trajectories on cells, implementing model selection to classify trajectories as either consistent with Brownian motion or with a two-state (diffusion coefficient) switching model. The incorporation of localisation accuracy is essential, as otherwise false detection of switching within a trajectory was observed and diffusion coefficient estimates were inflated. Since our analysis is on a single trajectory basis, we are able to examine heterogeneity between trajectories in a quantitative manner. Applying our method to the lymphocyte function-associated antigen 1 (LFA-1) receptor tagged with latex beads (4 s trajectories at 1000 frames s−1), both intra- and inter-trajectory heterogeneity were detected; 12–26% of trajectories display clear switching between diffusive states dependent on condition, whilst the inter-trajectory variability is highly structured with the diffusion coefficients being related by D 1 = 0.68D 0 − 1.5 × 104 nm2 s−1, suggestive that on these time scales we are detecting switching due to a single process. Further, the inter-trajectory variability of the diffusion coefficient estimates (1.6 × 102 − 2.6 × 105 nm2 s−1) is very much larger than the measurement uncertainty within trajectories, suggesting that LFA-1 aggregation and cytoskeletal interactions are significantly affecting mobility, whilst the timescales of these processes are distinctly different giving rise to inter- and intra-trajectory variability. There is also an ‘immobile’ state (defined as D < 3.0 × 103 nm2 s−1) that is rarely involved in switching, immobility occurring with the highest frequency (47%) under T cell activation (phorbol-12-myristate-13-acetate (PMA) treatment) with enhanced cytoskeletal attachment (calpain inhibition). Such ‘immobile’ states frequently display slow linear drift, potentially reflecting binding to a dynamic actin cortex. Our methods allow significantly more information to be extracted from individual trajectories (ultimately limited by time resolution and time-series length), and allow statistical comparisons between trajectories thereby quantifying inter-trajectory heterogeneity. Such methods will be highly informative for the construction and fitting of molecule mobility models within membranes incorporating aggregation, binding to the cytoskeleton, or traversing membrane microdomains. PMID:26473352

Automated Sensitivity Analysis of Interplanetary Trajectories

NASA Technical Reports Server (NTRS)

Knittel, Jeremy; Hughes, Kyle; Englander, Jacob; Sarli, Bruno

2017-01-01

This work describes a suite of Python tools known as the Python EMTG Automated Trade Study Application (PEATSA). PEATSA was written to automate the operation of trajectory optimization software, simplify the process of performing sensitivity analysis, and was ultimately found to out-perform a human trajectory designer in unexpected ways. These benefits will be discussed and demonstrated on sample mission designs.

PPP/nonreal-time trajectory program interface requirements and capabilities

NASA Technical Reports Server (NTRS)

Mcgavern, J. L.; Arbet, J. D.

1975-01-01

The selection process for interfacing a nonreal time trajectory program with the procedures and performance program is outlined; the interface provides summary data timelines for any desired trajectory profile. Consideration was given to two separate digital programs for satisfying capabilities. One was the CDC 6400 digital program BANDITO, and the second was the UNIVAC 1110 SVDS program.

Program For Simulation Of Trajectories And Events

NASA Technical Reports Server (NTRS)

Gottlieb, Robert G.

1992-01-01

Universal Simulation Executive (USE) program accelerates and eases generation of application programs for numerical simulation of continuous trajectories interrupted by or containing discrete events. Developed for simulation of multiple spacecraft trajectories with events as one spacecraft crossing the equator, two spacecraft meeting or parting, or firing rocket engine. USE also simulates operation of chemical batch processing factory. Written in Ada.

The Jupiter Icy Moons Orbiter reference trajectory

NASA Technical Reports Server (NTRS)

Whiffen, Gregory J.; Lam, Try

2006-01-01

The proposed NASA Jupiter Icy Moons Orbiter (JIMO) mission would have used a single spacecraft to orbit Callisto, Ganymede, and Europa in succession. The enormous Delta-Velocity required for this mission (nearly [25 km/s]) would necessitate the use of very high efficiency electric propulsion. The trajectory created for the proposed baseline JIMO mission may be the most complex trajectory ever designed. This paper describes the current reference trajectory in detail and describes the processes that were used to construct it.

ANALYTiC: An Active Learning System for Trajectory Classification.

PubMed

Soares Junior, Amilcar; Renso, Chiara; Matwin, Stan

2017-01-01

The increasing availability and use of positioning devices has resulted in large volumes of trajectory data. However, semantic annotations for such data are typically added by domain experts, which is a time-consuming task. Machine-learning algorithms can help infer semantic annotations from trajectory data by learning from sets of labeled data. Specifically, active learning approaches can minimize the set of trajectories to be annotated while preserving good performance measures. The ANALYTiC web-based interactive tool visually guides users through this annotation process.

The effect of spatial orientation on detecting motion trajectories in noise.

PubMed

Pavan, Andrea; Casco, Clara; Mather, George; Bellacosa, Rosilari M; Cuturi, Luigi F; Campana, Gianluca

2011-09-15

A series of experiments investigated the extent to which the spatial orientation of a signal line affects discrimination of its trajectory from the random trajectories of background noise lines. The orientation of the signal line was either parallel (iso-) or orthogonal (ortho-) to its motion direction and it was identical in all respects to the noise (orientation, length and speed) except for its motion direction, rendering the signal line indistinguishable from the noise on a frame-to-frame basis. We found that discrimination of ortho-trajectories was generally better than iso-trajectories. Discrimination of ortho-trajectories was largely immune to the effects of spatial jitter in the trajectory, and to variations in step size and line-length. Discrimination of iso-trajectories was reliable provided that step-size was not too short and did not exceed line length, and that the trajectory was straight. The new result that trajectory discrimination in moving line elements is modulated by line orientation suggests that ortho- and iso-trajectory discrimination rely upon two distinct mechanisms: iso-motion discrimination involves a 'motion-streak' process that combines motion information with information about orientation parallel to the motion trajectory, while ortho-motion discrimination involves extended trajectory facilitation in a network of receptive fields with orthogonal orientation tuning. Copyright © 2011 Elsevier Ltd. All rights reserved.

Trajectories of Ethnic-Racial Identity and Autonomy among Mexican-origin Adolescent Mothers in the U.S

PubMed Central

Umaña-Taylor, Adriana J.; Updegraff, Kimberly A.; Jahromi, Laudan B.; Zeiders, Katharine H.

2015-01-01

This study examined trajectories of ethnic-racial identity (ERI) and autonomy development among Mexican-origin adolescent females in the U.S. (N = 181; Mage at Wave 1 = 16.80 years, SD = 1.00) as they transitioned through the first five years of parenthood. Trajectories of ERI and autonomy also were examined in relation to psychosocial functioning. Unconditional latent growth models indicated significant growth in autonomy, ERI resolution, and ERI affirmation from middle to late adolescence. Conditional latent growth models indicated that autonomy and ERI exploration growth trajectories were positively associated with psychosocial adjustment. Although adolescent mothers are experiencing transitions that are not normative during adolescence, they also engage in normative developmental processes, and their engagement in such processes is linked with better adjustment. PMID:26450526

Multi-rendezvous low-thrust trajectory optimization using costate transforming and homotopic approach

NASA Astrophysics Data System (ADS)

Chen, Shiyu; Li, Haiyang; Baoyin, Hexi

2018-06-01

This paper investigates a method for optimizing multi-rendezvous low-thrust trajectories using indirect methods. An efficient technique, labeled costate transforming, is proposed to optimize multiple trajectory legs simultaneously rather than optimizing each trajectory leg individually. Complex inner-point constraints and a large number of free variables are one main challenge in optimizing multi-leg transfers via shooting algorithms. Such a difficulty is reduced by first optimizing each trajectory leg individually. The results may be, next, utilized as an initial guess in the simultaneous optimization of multiple trajectory legs. In this paper, the limitations of similar techniques in previous research is surpassed and a homotopic approach is employed to improve the convergence efficiency of the shooting process in multi-rendezvous low-thrust trajectory optimization. Numerical examples demonstrate that newly introduced techniques are valid and efficient.

Study of talcum charging status in parallel plate electrostatic separator based on particle trajectory analysis

NASA Astrophysics Data System (ADS)

Yunxiao, CAO; Zhiqiang, WANG; Jinjun, WANG; Guofeng, LI

2018-05-01

Electrostatic separation has been extensively used in mineral processing, and has the potential to separate gangue minerals from raw talcum ore. As for electrostatic separation, the particle charging status is one of important influence factors. To describe the talcum particle charging status in a parallel plate electrostatic separator accurately, this paper proposes a modern images processing method. Based on the actual trajectories obtained from sequence images of particle movement and the analysis of physical forces applied on a charged particle, a numerical model is built, which could calculate the charge-to-mass ratios represented as the charging status of particle and simulate the particle trajectories. The simulated trajectories agree well with the experimental results obtained by images processing. In addition, chemical composition analysis is employed to reveal the relationship between ferrum gangue mineral content and charge-to-mass ratios. Research results show that the proposed method is effective for describing the particle charging status in electrostatic separation.

Trajectories of ecosystem service change in restored peatlands

NASA Astrophysics Data System (ADS)

Evans, Martin; Shuttleworth, Emma; Pilkington, Mike; Allott, Tim; Walker, Jonathan; Spencer, Tom

2017-04-01

Peatlands provide a wide range of ecosystem services but across the world degradation of these systems through a range of human impacts has had a negative effect on the provision of these services. A wide variety of peatland restoration approaches have been developed with the aim of mitigating these impacts. Understanding of trajectories of change in ecosystem structure and function is central to evaluating the efficacy of these restoration methods. This paper considers data on post-restoration trajectories of water table change, vegetation recovery, runoff production and water quality based on extensive data from peatland restoration work in the southern Pennines of the U.K. Data have been compiled from multiple restoration initiatives undertaken across the region, spanning up to 12 years post restoration. The data show variations in the time scale of ecosystem change which are indicative of the process basis of the ecosystem trajectories. Rapid changes in runoff are controlled by physical changes to the peatland surface. These are contrasted with longer term evolution of vegetation and water table behaviour which suggest ongoing recovery as the ecosystem adjusts to the restoration process. In order to assess restoration of ecosystem function, and so of ecosystem services, it is important that the process links between ecosystem structure and function are well understood. Establishing typical restoration trajectories can be of practical use in determining restoration project milestones, and can also provide insight into the nature of these process links.

Children's School Readiness: Implications for Eliminating Future Disparities in Health and Education

ERIC Educational Resources Information Center

Pagani, Linda S.; Fitzpatrick, Caroline

2014-01-01

Background: School-entry characteristics predict adult educational attainment, which forecasts dispositions toward disease prevention. Health and education risks can also be transmitted from one generation to the next. As such, school readiness forecasts a set of intertwined biopsychosocial trajectories that can influence the developmental…

Language Growth in Children with Heterogeneous Language Disorders: A Population Study

ERIC Educational Resources Information Center

Norbury, Courtenay Frazier; Vamvakas, George; Gooch, Debbie; Baird, Gillian; Charman, Tony; Simonoff, Emily; Pickles, Andrew

2017-01-01

Background: Language development has been characterised by significant individual stability from school entry. However, the extent to which trajectories of language growth vary in children with language disorder as a function of co-occurring developmental challenges is a question of theoretical import, with implications for service provision.…

The physics of badminton

NASA Astrophysics Data System (ADS)

Cohen, Caroline; Darbois Texier, Baptiste; Quéré, David; Clanet, Christophe

2015-06-01

The conical shape of a shuttlecock allows it to flip on impact. As a light and extended particle, it flies with a pure drag trajectory. We first study the flip phenomenon and the dynamics of the flight and then discuss the implications on the game. Lastly, a possible classification of different shots is proposed.

Understanding Resilience in Educational Trajectories: Implications for Protective Possibilities

ERIC Educational Resources Information Center

Morrison, Gale M.; Brown, Megan; D'Incau, Barbara; O'Farrell, Stacy Larson; Furlong, Michael J.

2006-01-01

A growing body of literature on risk and resilience, school engagement, and positive psychology offers school psychologists new perspectives with which to consider students' progress through school. This literature emphasizes the importance of monitoring student internal and external assets. In this article, a framework is reviewed that highlights…

Career Trajectories of Older Women: Implications for Career Guidance

ERIC Educational Resources Information Center

Bimrose, Jenny; McMahon, Mary; Watson, Mark

2013-01-01

As work and employment transitions become more frequent and difficult, the demand for formal career guidance increases. Women are likely to experience structural labour market disadvantage and may benefit from formal support that is sympathetic to their particular needs. Yet the traditional psychological paradigms that dominate career guidance…

Hippocampal Shape Abnormalities of Patients with Childhood-Onset Schizophrenia and Their Unaffected Siblings

ERIC Educational Resources Information Center

Johnson, Sarah L. M.; Wang, Lei; Alpert, Kathryn I.; Greenstein, Deanna; Clasen, Liv; Lalonde, Francois; Miller, Rachel; Rapoport, Judith; Gogtay, Nitin

2013-01-01

Objective: The hippocampus has been implicated in the pathogenesis of schizophrenia, and hippocampal volume deficits have been a consistently reported abnormality, but the subregional specificity of the deficits remains unknown. The authors explored the nature and developmental trajectory of subregional shape abnormalities of the hippocampus in…

Typologies of Family Functioning and Children's Adjustment during the Early School Years

ERIC Educational Resources Information Center

Sturge-Apple, Melissa L.; Davies, Patrick T.; Cummings, E. Mark

2010-01-01

Guided by family systems theory, the present study sought to identify patterns of family functioning from observational assessments of interparental, parent-child, and triadic contexts. In addition, it charted the implications for patterns of family functioning for children's developmental trajectories of adjustment in the school context across…

Adolescent-Perceived Parent and Teacher Overestimation of Mathematics Ability: Developmental Implications for Students' Mathematics Task Values

ERIC Educational Resources Information Center

Gniewosz, Burkhard; Watt, Helen M. G.

2017-01-01

This study examines whether and how student-perceived parents' and teachers' overestimation of students' own perceived mathematical ability can explain trajectories for adolescents' mathematical task values (intrinsic and utility) controlling for measured achievement, following expectancy-value and self-determination theories. Longitudinal data…

South Africa's Economic Development Trajectory: Implications for Skills Development

ERIC Educational Resources Information Center

Mayer, Marina J.; Altman, Miriam

2005-01-01

This article argues that skills development in South Africa must be aligned to the economic and political imperatives of reducing unemployment and poverty, while fostering growth and international competitiveness. The legacy of a resource-based economy, overlaid by apartheid policies, has resulted in widespread poverty, inequality and unemployment…

Motor Origins of Tool Use

ERIC Educational Resources Information Center

Kahrs, Bjorn A.; Jung, Wendy P.; Lockman, Jeffrey J.

2013-01-01

The current study examines the developmental trajectory of banging movements and its implications for tool use development. Twenty (6- to 15-month-old) infants wore reflective markers while banging a handled cube; movements were recorded at 240 Hz. Results indicated that through the second half-year, banging movements undergo developmental changes…

Fast optimization of glide vehicle reentry trajectory based on genetic algorithm

NASA Astrophysics Data System (ADS)

Jia, Jun; Dong, Ruixing; Yuan, Xuejun; Wang, Chuangwei

2018-02-01

An optimization method of reentry trajectory based on genetic algorithm is presented to meet the need of reentry trajectory optimization for glide vehicle. The dynamic model for the glide vehicle during reentry period is established. Considering the constraints of heat flux, dynamic pressure, overload etc., the optimization of reentry trajectory is investigated by utilizing genetic algorithm. The simulation shows that the method presented by this paper is effective for the optimization of reentry trajectory of glide vehicle. The efficiency and speed of this method is comparative with the references. Optimization results meet all constraints, and the on-line fast optimization is potential by pre-processing the offline samples.

Child Dopamine Transporter Genotype and Parenting: Evidence for Evocative Gene-Environment Correlations

PubMed Central

Hayden, Elizabeth P.; Hanna, Brigitte; Sheikh, Haroon I.; Laptook, Rebecca S.; Kim, Jiyon; Singh, Shiva M.; Klein, Daniel N.

2017-01-01

The dopamine transporter (DAT1) gene is implicated in psychopathology risk. While the processes by which this gene exerts its effects on risk are poorly understood, a small body of research suggests that DAT1 influences early emerging negative emotionality (NE), a marker of children’s psychopathology risk. As child NE evokes negative parenting practices, the DAT1 may also play a role in gene-environment correlations. To test this model, children (N = 365) were genotyped for DAT1 and participated in standardized parent-child interaction tasks with their primary caregiver. The DAT1 9-repeat variant was associated with child negative affect expressed toward the parent during parent-child interactions, and parents of children with a 9-repeat allele exhibited more hostility and lower guidance/engagement than parents of children without a 9-repeat allele. These gene-environment associations were partially mediated by child negative affect toward the parent. Findings implicate a specific polymorphism in eliciting negative parenting, suggesting that evocative associations play a role in elevating children’s risk for emotional trajectories toward psychopathology risk. PMID:23398760

Who Were the Early Adopters of Dabigatran? An Application of Group-Based Trajectory Models

PubMed Central

Lo-Ciganic, Wei-Hsuan; Gellad, Walid F.; Huskamp, Haiden A.; Choudhry, Niteesh K.; Chang, Chung-Chou H.; Zhang, Ruoxin; Jones, Bobby L.; Guclu, Hasan; Richards-Shubik, Seth; Donohue, Julie M.

2016-01-01

BACKGROUND Variation in physician adoption of new medications is poorly understood. Traditional approaches (e.g., measuring time to first prescription) may mask substantial heterogeneity in technology adoption. OBJECTIVE Apply group-based trajectory models to examine the physician adoption of dabigratran, a novel anticoagulant. METHODS A retrospective cohort study using prescribing data from IMS Xponent™ on all Pennsylvania physicians regularly prescribing anticoagulants (n=3,911) and data on their characteristics from the American Medical Association Masterfile. We examined time to first dabigatran prescription as well as group-based trajectory models to identify adoption trajectories in the first 15 months. Factors associated with rapid adoption were examined using multivariate logistic regressions. OUTCOMES Trajectories of monthly share of oral anticoagulant prescriptions for dabigatran RESULTS We identified five distinct adoption trajectories: 3.7% rapidly and extensively adopted dabigatran (adopting in ≤3 months with 45% of prescriptions) and 13.4% were rapid and moderate adopters (≤3 months with 20% share). Two groups accounting for 21.6% and 16.1% of physicians, respectively, were slower to adopt (6 to 10 months post-introduction) and dabigatran accounted for <10% share. Nearly half (45.2%) of anticoagulant prescribers did not adopt dabigatran. Cardiologists were much more likely than primary care physicians to rapidly adopt (odds ratio [OR] 12.2, 95%CI: 9.27–16.1) as were younger prescribers (age 36–45 years: OR 1.49, 95%CI: 1.13–1.95, age 46–55: OR 1.34, 95%CI 1.07–1.69 vs. >55 years). CONCLUSIONS Trajectories of physician adoption of dabigatran were highly variable with significant differences across specialties. Heterogeneity in physician adoption has potential implications for the cost and effectiveness of treatment. PMID:27116109

Complexity and the Fractional Calculus

DTIC Science & Technology

2013-01-01

these trajectories over the entire Lotka - Volterra cycle thereby generating the mistaken impression that the resulting average trajectory reaches...interpreted as a form of phase decor- relation process rather than one with friction. The fractional version of the popular Lotka - Volterra ecological...trajectory is an ordinary Lotka - Volterra cycle in the operational time . Transitioning from the operational time to the chronological time spreads

Automated Sensitivity Analysis of Interplanetary Trajectories for Optimal Mission Design

NASA Technical Reports Server (NTRS)

Knittel, Jeremy; Hughes, Kyle; Englander, Jacob; Sarli, Bruno

2017-01-01

This work describes a suite of Python tools known as the Python EMTG Automated Trade Study Application (PEATSA). PEATSA was written to automate the operation of trajectory optimization software, simplify the process of performing sensitivity analysis, and was ultimately found to out-perform a human trajectory designer in unexpected ways. These benefits will be discussed and demonstrated on sample mission designs.

Global Optimization of Low-Thrust Interplanetary Trajectories Subject to Operational Constraints

NASA Technical Reports Server (NTRS)

Englander, Jacob Aldo; Vavrina, Matthew; Hinckley, David

2016-01-01

Low-thrust electric propulsion provides many advantages for mission to difficult targets-Comets and asteroids-Mercury-Outer planets (with sufficient power supply)Low-thrust electric propulsion is characterized by high power requirements but also very high specific impulse (Isp), leading to very good mass fractions. Low-thrust trajectory design is a very different process from chemical trajectory.

Operator-assisted planning and execution of proximity operations subject to operational constraints

NASA Technical Reports Server (NTRS)

Grunwald, Arthur J.; Ellis, Stephen R.

1991-01-01

Future multi-vehicle operations will involve multiple scenarios that will require a planning tool for the rapid, interactive creation of fuel-efficient trajectories. The planning process must deal with higher-order, non-linear processes involving dynamics that are often counter-intuitive. The optimization of resulting trajectories can be difficult to envision. An interaction proximity operations planning system is being developed to provide the operator with easily interpreted visual feedback of trajectories and constraints. This system is hosted on an IRIS 4D graphics platform and utilizes the Clohessy-Wiltshire equations. An inverse dynamics algorithm is used to remove non-linearities while the trajectory maneuvers are decoupled and separated in a geometric spreadsheet. The operator has direct control of the position and time of trajectory waypoints to achieve the desired end conditions. Graphics provide the operator with visualization of satisfying operational constraints such as structural clearance, plume impingement, approach velocity limits, and arrival or departure corridors. Primer vector theory is combined with graphical presentation to improve operator understanding of suggested automated system solutions and to allow the operator to review, edit, or provide corrective action to the trajectory plan.

Individual Differences in Trajectories of Emotion Regulation Processes: The Effects of Maternal Depressive Symptomatology and Children's Physiological Regulation

ERIC Educational Resources Information Center

Blandon, Alysia Y.; Calkins, Susan D.; Keane, Susan P.; O'Brien, Marion

2008-01-01

Trajectories of emotion regulation processes were examined in a community sample of 269 children across the ages of 4 to 7 using hierarchical linear modeling. Maternal depressive symptomatology (Symptom Checklist-90) and children's physiological reactivity (respiratory sinus arrhythmia [RSA]) and vagal regulation ([delta]RSA) were explored as…

Mapping the Developmental Trajectory and Correlates of Enhanced Pitch Perception on Speech Processing in Adults with ASD

ERIC Educational Resources Information Center

Mayer, Jennifer L.; Hannent, Ian; Heaton, Pamela F.

2016-01-01

Whilst enhanced perception has been widely reported in individuals with Autism Spectrum Disorders (ASDs), relatively little is known about the developmental trajectory and impact of atypical auditory processing on speech perception in intellectually high-functioning adults with ASD. This paper presents data on perception of complex tones and…

Catching What We Can't See: Manual Interception of Occluded Fly-Ball Trajectories

PubMed Central

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories. PMID:23166653

Catching what we can't see: manual interception of occluded fly-ball trajectories.

PubMed

Bosco, Gianfranco; Delle Monache, Sergio; Lacquaniti, Francesco

2012-01-01

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories.

Developmental Pathways from Childhood Aggression-Disruptiveness, Chronic Peer Rejection and Deviant Friendships to Early-Adolescent Rule Breaking

PubMed Central

Ettekal, Idean; Ladd, Gary W.

2015-01-01

Childhood aggression-disruptiveness, chronic peer rejection, and deviant friendships were examined as predictors of early-adolescent rule breaking behaviors. Using a sample of 383 children (193 girls and 190 boys) who were followed from ages 6 to 14, peer rejection trajectories were identified and incorporated into a series of alternative models to assess how chronic peer rejection and deviant friendships mediate the association between stable childhood aggression-disruptiveness and early-adolescent rule breaking. There were multiple mediated pathways to rule breaking that included both behavioral and relational risk factors and findings were consistent for boys and girls. Results have implications for better understanding the influence of multiple social processes in the continuity of antisocial behaviors from middle childhood to early adolescence. PMID:25403544

Trajectories of affective states in adolescent hockey players: turning point and motivational antecedents.

PubMed

Gaudreau, Patrick; Amiot, Catherine E; Vallerand, Robert J

2009-03-01

This study examined longitudinal trajectories of positive and negative affective states with a sample of 265 adolescent elite hockey players followed across 3 measurement points during the 1st 11 weeks of a season. Latent class growth modeling, incorporating a time-varying covariate and a series of predictors assessed at the onset of the season, was used to chart out distinct longitudinal trajectories of affective states. Results provided evidence for 3 trajectories of positive affect and 3 trajectories of negative affect. Two of these trajectories were deflected by team selection, a seasonal turning point occurring after the 1st measurement point. Furthermore, the trajectories of positive and negative affective states were predicted by theoretically driven predictors assessed at the start of the season (i.e., self-determination, need satisfaction, athletic identity, and school identity). These results contribute to a better understanding of the motivational, social, and identity-related processes associated with the distinct affective trajectories of athletes participating in elite sport during adolescence.

A Probabilistic Framework for Constructing Temporal Relations in Replica Exchange Molecular Trajectories.

PubMed

Chattopadhyay, Aditya; Zheng, Min; Waller, Mark Paul; Priyakumar, U Deva

2018-05-23

Knowledge of the structure and dynamics of biomolecules is essential for elucidating the underlying mechanisms of biological processes. Given the stochastic nature of many biological processes, like protein unfolding, it's almost impossible that two independent simulations will generate the exact same sequence of events, which makes direct analysis of simulations difficult. Statistical models like Markov Chains, transition networks etc. help in shedding some light on the mechanistic nature of such processes by predicting long-time dynamics of these systems from short simulations. However, such methods fall short in analyzing trajectories with partial or no temporal information, for example, replica exchange molecular dynamics or Monte Carlo simulations. In this work we propose a probabilistic algorithm, borrowing concepts from graph theory and machine learning, to extract reactive pathways from molecular trajectories in the absence of temporal data. A suitable vector representation was chosen to represent each frame in the macromolecular trajectory (as a series of interaction and conformational energies) and dimensionality reduction was performed using principal component analysis (PCA). The trajectory was then clustered using a density-based clustering algorithm, where each cluster represents a metastable state on the potential energy surface (PES) of the biomolecule under study. A graph was created with these clusters as nodes with the edges learnt using an iterative expectation maximization algorithm. The most reactive path is conceived as the widest path along this graph. We have tested our method on RNA hairpin unfolding trajectory in aqueous urea solution. Our method makes the understanding of the mechanism of unfolding in RNA hairpin molecule more tractable. As this method doesn't rely on temporal data it can be used to analyze trajectories from Monte Carlo sampling techniques and replica exchange molecular dynamics (REMD).

Insights on TTL Dehydration Mechanisms from Microphysical Modelling of Aircraft Observations

NASA Technical Reports Server (NTRS)

Ueyama, R.; Pfister, L.; Jensen, E.

2014-01-01

The Tropical Tropopause Layer (TTL), a transition layer between the upper troposphere and lower stratosphere in the tropics, serves as the entryway of various trace gases into the stratosphere. Of particular interest is the transport of water vapor through the TTL, as WV is an important greenhouse gas and also plays a significant role in stratospheric chemistry by affecting polar stratospheric cloud formation and the ozone budget. While the dominant control of stratospheric water vapor by tropical cold point temperatures via the "freeze-drying" process is generally well understood, the details of the TTL dehydration mechanisms, including the relative roles of deep convection, atmospheric waves and cloud microphysical processes, remain an active area of research. The dynamical and microphysical processes that influence TTL water vapor concentrations are investigated in simulations of cloud formation and dehydration along air parcel trajectories. We first confirm the validity of our Lagrangian models in a case study involving measurements from the Airborne Tropical TRopopause EXperiment (ATTREX) flights over the central and eastern tropical Pacific in Oct-Nov 2011 and Jan-Feb 2013. ERA-Interim winds and seasonal mean heating rates from Yang et al. (2010) are used to advance parcels back in time from the flight tracks, and time-varying vertical profiles of water vapor along the diabatic trajectories are calculated in a one-dimensional cloud model as in Jensen and Pfister (2004) but with more reliable temperature field, wave and convection schemes. The simulated water vapor profiles demonstrate a significant improvement over estimates based on the Lagrangian Dry Point, agreeing well with aircraft observations when the effects of cloud microphysics, subgrid-scale gravity waves and convection are included. Following this approach, we examine the dynamical and microphysical control of TTL water vapor in the 30ºS-30ºN latitudinal belt and elucidate the dominant processes in the winter and summer seasons. Implications of the TTL dehydration processes for the regulation of global stratospheric humidity will be discussed.

Ballistic projectile trajectory determining system

DOEpatents

Karr, T.J.

1997-05-20

A computer controlled system determines the three-dimensional trajectory of a ballistic projectile. To initialize the system, predictions of state parameters for a ballistic projectile are received at an estimator. The estimator uses the predictions of the state parameters to estimate first trajectory characteristics of the ballistic projectile. A single stationary monocular sensor then observes the actual first trajectory characteristics of the ballistic projectile. A comparator generates an error value related to the predicted state parameters by comparing the estimated first trajectory characteristics of the ballistic projectile with the observed first trajectory characteristics of the ballistic projectile. If the error value is equal to or greater than a selected limit, the predictions of the state parameters are adjusted. New estimates for the trajectory characteristics of the ballistic projectile are made and are then compared with actual observed trajectory characteristics. This process is repeated until the error value is less than the selected limit. Once the error value is less than the selected limit, a calculator calculates trajectory characteristics such a the origin and destination of the ballistic projectile. 8 figs.

Prediction during statistical learning, and implications for the implicit/explicit divide

PubMed Central

Dale, Rick; Duran, Nicholas D.; Morehead, J. Ryan

2012-01-01

Accounts of statistical learning, both implicit and explicit, often invoke predictive processes as central to learning, yet practically all experiments employ non-predictive measures during training. We argue that the common theoretical assumption of anticipation and prediction needs clearer, more direct evidence for it during learning. We offer a novel experimental context to explore prediction, and report results from a simple sequential learning task designed to promote predictive behaviors in participants as they responded to a short sequence of simple stimulus events. Predictive tendencies in participants were measured using their computer mouse, the trajectories of which served as a means of tapping into predictive behavior while participants were exposed to very short and simple sequences of events. A total of 143 participants were randomly assigned to stimulus sequences along a continuum of regularity. Analysis of computer-mouse trajectories revealed that (a) participants almost always anticipate events in some manner, (b) participants exhibit two stable patterns of behavior, either reacting to vs. predicting future events, (c) the extent to which participants predict relates to performance on a recall test, and (d) explicit reports of perceiving patterns in the brief sequence correlates with extent of prediction. We end with a discussion of implicit and explicit statistical learning and of the role prediction may play in both kinds of learning. PMID:22723817

Potential for Integrating Entry Guidance into the Multi-Disciplinary Entry Vehicle Optimization Environment

NASA Technical Reports Server (NTRS)

D'souza, Sarah N.; Kinney, David J.; Garcia, Joseph A.; Sarigul-Klijn, Nesrin

2014-01-01

The state-of-the-art in vehicle design decouples flight feasible trajectory generation from the optimization process of an entry spacecraft shape. The disadvantage to this decoupled process is seen when a particular aeroshell does not meet in-flight requirements when integrated into Guidance, Navigation, and Control simulations. It is postulated that the integration of a guidance algorithm into the design process will provide a real-time, rapid trajectory generation technique to enhance the robustness of vehicle design solutions. The potential benefit of this integration is a reduction in design cycles (possible cost savings) and increased accuracy in the aerothermal environment (possible mass savings). This work examines two aspects: 1) the performance of a reference tracking guidance algorithm for five different geometries with the same reference trajectory and 2) the potential of mass savings from improved aerothermal predictions. An Apollo Derived Guidance (ADG) algorithm is used in this study. The baseline geometry and five test case geometries were flown using the same baseline trajectory. The guided trajectory results are compared to separate trajectories determined in a vehicle optimization study conducted for NASA's Mars Entry, Descent, and Landing System Analysis. This study revealed several aspects regarding the potential gains and required developments for integrating a guidance algorithm into the vehicle optimization environment. First, the generation of flight feasible trajectories is only as good as the robustness of the guidance algorithm. The set of dispersed geometries modelled aerodynamic dispersions that ranged from +/-1% to +/-17% and a single extreme case was modelled where the aerodynamics were approximately 80% less than the baseline geometry. The ADG, as expected, was able to guide the vehicle into the aeroshell separation box at the target location for dispersions up to 17%, but failed for the 80% dispersion cases. Finally, the results revealed that including flight feasible trajectories for a set of dispersed geometries has the potential to save mass up to 430 kg.

Self-esteem development across the life span: a longitudinal study with a large sample from Germany.

PubMed

Orth, Ulrich; Maes, Jürgen; Schmitt, Manfred

2015-02-01

The authors examined the development of self-esteem across the life span. Data came from a German longitudinal study with 3 assessments across 4 years of a sample of 2,509 individuals ages 14 to 89 years. The self-esteem measure used showed strong measurement invariance across assessments and birth cohorts. Latent growth curve analyses indicated that self-esteem follows a quadratic trajectory across the life span, increasing during adolescence, young adulthood, and middle adulthood, reaching a peak at age 60 years, and then declining in old age. No cohort effects on average levels of self-esteem or on the shape of the trajectory were found. Moreover, the trajectory did not differ across gender, level of education, or for individuals who had lived continuously in West versus East Germany (i.e., the 2 parts of Germany that had been separate states from 1949 to 1990). However, the results suggested that employment status, household income, and satisfaction in the domains of work, relationships, and health contribute to a more positive life span trajectory of self-esteem. The findings have significant implications, because they call attention to developmental stages in which individuals may be vulnerable because of low self-esteem (such as adolescence and old age) and to factors that predict successful versus problematic developmental trajectories. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Parent-child relationships of boys in different offending trajectories. A developmental perspective

PubMed Central

Keijsers, Loes; Loeber, Rolf; Branje, Susan; Meeus, Wim

2012-01-01

Background This study tested the theoretical assumption that transformations of parent-child relationships in late childhood and adolescence would differ for boys following different offending trajectories. Methods Using longitudinal multiinformant data of 503 boys (ages 7–19), we conducted Growth Mixture Modeling to extract offending trajectories. Developmental changes in child reports of parent-child joint activities and relationship quality were examined using Latent Growth Curves. Results Five offending trajectories were found: non-offenders, moderate childhood offenders, adolescent-limited offenders, serious childhood offenders, and serious persistent offenders. Non-offenders reported high and stable levels of relationship quality between age 10 and 16. Adolescent-limited offenders reported a similarly high relationship quality as non-offenders at ages 7 and 10, but a lower and decreasing relationship quality in adolescence. Compared with non-offenders, serious persistent offenders reported poorer parent-child relationship quality at all ages, and a decreasing relationship quality in adolescence. Serious persistent offenders and adolescent-limited offenders reported similar levels and changes in parent-child relationship quality in adolescence. Although serious persistent offenders reported fewer joint activities at age 10 and 13 than non-offenders, a similar linear decrease in joint activities in early to middle adolescence was found for boys in each trajectory. Conclusion Developmental changes in parent-child relationship quality differ for different types of offenders. This finding has scientific and practical implications. PMID:22816682

Response trajectories reveal conflict phase in image-word mismatch.

PubMed

van Vugt, Floris T; Cavanagh, Patrick

2012-02-01

In the present study, response trajectories were used in a picture–word conflict task to determine the timing of intermediate processing stages that are relatively inaccessible to response time measures. A marker was placed above or below the word ABOVE or BELOW so that its location was congruent or in conflict with the word's meaning. To report either word location(above or below the marker) or word meaning, participants moved a mouse upward toward the appropriate top left or right answer corner on the display screen.Their response trajectories showed a number of distinctive features: First, at about 200 ms after stimulus onset(the "decision moment"), the trajectory abruptly began to arc toward the appropriate answer corner; second,when the word's meaning and position were in conflict,the trajectory showed an interruption that continued until the conflict was resolved. By varying the SOA of the word and marker onsets, we found that the word meaning and word position became available at approximately 325 ms and 251 ms, respectively, after their onsets, and that the delay to resolve conflicts was about 138 ms. The timing of these response trajectory events was more stable than any extracted from the final response times, demonstrating the power of response trajectories to reveal processing stages that are only poorly resolved, if at all, by response time measures [added].

Rapid Preliminary Design of Interplanetary Trajectories Using the Evolutionary Mission Trajectory Generator

NASA Technical Reports Server (NTRS)

Englander, Jacob

2016-01-01

This set of tutorial slides is an introduction to the Evolutionary Mission Trajectory Generator (EMTG), NASA Goddard Space Flight Center's autonomous tool for preliminary design of interplanetary missions. This slide set covers the basics of creating and post-processing simple interplanetary missions in EMTG using both high-thrust chemical and low-thrust electric propulsion along with a variety of operational constraints.

Developmental Trajectories of Social Skills during Early Childhood and Links to Parenting Practices in a Japanese Sample.

PubMed

Takahashi, Yusuke; Okada, Kensuke; Hoshino, Takahiro; Anme, Tokie

2015-01-01

This study used data from a nationwide survey in Japan to model the developmental course of social skills during early childhood. The goals of this study were to identify longitudinal profiles of social skills between 2 and 5 years of age using a group-based trajectory approach, and to investigate whether and to what extent parenting practices at 2 years of age predicted developmental trajectories of social skills during the preschool period. A relatively large sample of boys and girls (N > 1,000) was assessed on three social skill dimensions (Cooperation, Self-control, and Assertion) at four time points (ages 2, 3, 4, and 5), and on four parenting practices (cognitive and emotional involvement, avoidance of restriction and punishment, social stimulation, and social support for parenting) at age 2. The results indicated that for each social skill dimension, group-based trajectory models identified three distinct trajectories: low, moderate, and high. Multinomial regression analysis revealed that parenting practice variables showed differential contributions to development of child social skills. Specifically, Cooperation and Assertion were promoted by cognitive and emotional involvement, Self-control by social stimulation, and Assertion by avoidance of restriction and punishment. Abundant social support for parenting was not associated with higher child social skills trajectories. We found heterogeneity in developmental profiles of social skills during the preschool ages, and we identified parenting practices that contributed to different patterns of social skills development. We discussed the implications of higher-quality parenting practices on the improvement of child social skills across early childhood.

Developmental Trajectories of Social Skills during Early Childhood and Links to Parenting Practices in a Japanese Sample

PubMed Central

Takahashi, Yusuke; Okada, Kensuke; Hoshino, Takahiro; Anme, Tokie

2015-01-01

This study used data from a nationwide survey in Japan to model the developmental course of social skills during early childhood. The goals of this study were to identify longitudinal profiles of social skills between 2 and 5 years of age using a group-based trajectory approach, and to investigate whether and to what extent parenting practices at 2 years of age predicted developmental trajectories of social skills during the preschool period. A relatively large sample of boys and girls (N > 1,000) was assessed on three social skill dimensions (Cooperation, Self-control, and Assertion) at four time points (ages 2, 3, 4, and 5), and on four parenting practices (cognitive and emotional involvement, avoidance of restriction and punishment, social stimulation, and social support for parenting) at age 2. The results indicated that for each social skill dimension, group-based trajectory models identified three distinct trajectories: low, moderate, and high. Multinomial regression analysis revealed that parenting practice variables showed differential contributions to development of child social skills. Specifically, Cooperation and Assertion were promoted by cognitive and emotional involvement, Self-control by social stimulation, and Assertion by avoidance of restriction and punishment. Abundant social support for parenting was not associated with higher child social skills trajectories. We found heterogeneity in developmental profiles of social skills during the preschool ages, and we identified parenting practices that contributed to different patterns of social skills development. We discussed the implications of higher-quality parenting practices on the improvement of child social skills across early childhood. PMID:26267439

Appraisal underpinnings of affective chronometry: the role of appraisals in emotion habituation.

PubMed

Tong, Eddie M W; Bishop, George D; Enkelmann, Hwee Chong; Why, Yong Peng; Diong, Siew Maan; Khader, Majeed; Ang, Jansen

2009-08-01

In light of the lack of studies examining the cognitive components of affective chronometry, this research examined the appraisals associated with emotion habituation, using anger as the emotion of focus. Anger and its appraisals were assessed repeatedly over a day in the participants' naturalistic contexts. The trajectory of decline in anger over time after its first appearance was found to be a function of chronic coping styles. More importantly, the trajectories of anger-related appraisals generally corresponded to that of anger and were also moderated by coping styles in ways consistent with the moderating effects of coping styles on anger. Implications of these results for affective chronometry research and for appraisal research are discussed.

System and method for bullet tracking and shooter localization

DOEpatents

Roberts, Randy S [Livermore, CA; Breitfeller, Eric F [Dublin, CA

2011-06-21

A system and method of processing infrared imagery to determine projectile trajectories and the locations of shooters with a high degree of accuracy. The method includes image processing infrared image data to reduce noise and identify streak-shaped image features, using a Kalman filter to estimate optimal projectile trajectories, updating the Kalman filter with new image data, determining projectile source locations by solving a combinatorial least-squares solution for all optimal projectile trajectories, and displaying all of the projectile source locations. Such a shooter-localization system is of great interest for military and law enforcement applications to determine sniper locations, especially in urban combat scenarios.

Suborbital spaceplane optimization using non-stationary Gaussian processes

NASA Astrophysics Data System (ADS)

Dufour, Robin; de Muelenaere, Julien; Elham, Ali

2014-10-01

This paper presents multidisciplinary design optimization of a sub-orbital spaceplane. The optimization includes three disciplines: the aerodynamics, the structure and the trajectory. An Adjoint Euler code is used to calculate the aerodynamic lift and drag of the vehicle as well as their derivatives with respect to the design variables. A new surrogate model has been developed based on a non-stationary Gaussian process. That model was used to estimate the aerodynamic characteristics of the vehicle during the trajectory optimization. The trajectory of thevehicle has been optimized together with its geometry in order to maximize the amount of payload that can be carried by the spaceplane.

ORIGINS OF FINE AEROSOL MASS IN THE BALTIMORE-WASHINGTON CORRIDOR: IMPLICATIONS FROM OBSERVATION, FACTOR ANALYSIS, AND ENSEMBLE AIR PARCEL BACK TRAJECTORIES. (R826238)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Are Approaches to Learning in Kindergarten Associated with Academic and Social Competence Similarly?

ERIC Educational Resources Information Center

Razza, Rachel A.; Martin, Anne; Brooks-Gunn, Jeanne

2015-01-01

Background: Approaches to learning (ATL) is a key domain of school readiness with important implications for children's academic trajectories. Interestingly, however, the impact of early ATL on children's social competence has not been examined. Objective: This study examines associations between children's ATL at age 5 and academic achievement…

Concept analysis of good death in long term care residents.

PubMed

Krishnan, Preetha

2017-01-02

The purpose of this concept analysis paper is to delineate the meaning of good death in long term care (LTC) settings and examine its implications for nursing. The Walker and Avant (2011) method was chosen for this analysis. An in depth literature review identifies uses of the concept and determines the defining attributes of the good death. This paper also illustrates case presentations, antecedents, consequences, empirical referents and implications for clinical practice to clarify the concept of 'good death' in this population. In LTC, death is experienced frequently and is considered the ultimate outcome for most admissions. Much of the existing research on end-of-life care has focused on community dwelling cancer patients whose death trajectory is predictable and who may remain cognitively intact until actively dying. In contrast, the LTC population is older and more likely to suffer from dementia and experience chronic illness for long periods prior to death, and they follow a less predictable death trajectory. In this century, death became the province of older people and the assurance of a good death became the responsibility of those caring for them.

Use of automated rendezvous trajectory planning to improve spacecraft operations efficiency

NASA Technical Reports Server (NTRS)

Mulder, Tom A.

1991-01-01

The current planning process for space shuttle rendezvous with a second Earth-orbiting vehicle is time consuming and costly. It is a labor-intensive, manual process performed pre-mission with the aid of specialized maneuver processing tools. Real-time execution of a rendezvous plan must closely follow a predicted trajectory, and targeted solutions leading up to the terminal phase are computed on the ground. Despite over 25 years of Gemini, Apollo, Skylab, and shuttle vehicle-to-vehicle rendezvous missions flown to date, rendezvous in Earth orbit still requires careful monitoring and cannot be taken for granted. For example, a significant trajectory offset was experienced during terminal phase rendezvous of the STS-32 Long Duration Exposure Facility retrieval mission. Several improvements can be introduced to the present rendezvous planning process to reduce costs, produce more fuel-efficient profiles, and increase the probability of mission success.

Corpus callosum volumes in the 5 years following the first-episode of schizophrenia: Effects of antipsychotics, chronicity and maturation.

PubMed

de Moura, Mariana T M; Zanetti, Marcus V; Duran, Fabio L S; Schaufelberger, Maristela S; Menezes, Paulo R; Scazufca, Marcia; Busatto, Geraldo F; Serpa, Mauricio H

2018-01-01

White matter (WM) structural changes, particularly affecting the corpus callosum (CC), seem to be critically implicated in psychosis. Whether such abnormalities are progressive or static is still a matter of debate in schizophrenia research. Aberrant maturation processes might also influence the longitudinal trajectory of age-related CC changes in schizophrenia patients. We investigated whether patients with first-episode schizophrenia-related psychoses (FESZ) would present longitudinal CC and whole WM volume changes over the 5 years after disease onset. Thirty-two FESZ patients and 34 controls recruited using a population-based design completed a 5-year assessment protocol, including structural MRI scanning at baseline and follow-up. The linear effects of disease duration, clinical outcome and antipsychotic (AP) use over time on WM and CC volumes were studied using both voxelwise and volume-based morphometry analyses. We also examined maturation/aging abnormalities through cross-sectional analyses of age-related trajectories of total WM and CC volume changes. No interaction between diagnosis and time was observed, and clinical outcome did not influence CC volumes in patients. On the other hand, FESZ patients continuously exposed to AP medication showed volume increase over time in posterior CC. Curve-estimation analyses revealed a different aging pattern in FESZ patients versus controls: while patients displayed a linear decline of total WM and anterior CC volumes with age, a non-linear trajectory of total WM and relative preservation of CC volumes were observed in controls. Continuous AP exposure can influence CC morphology during the first years after schizophrenia onset. Schizophrenia is associated with an abnormal pattern of total WM and anterior CC aging during non-elderly adulthood, and this adds complexity to the discussion on the static or progressive nature of structural abnormalities in psychosis.

Multi-Objective Hybrid Optimal Control for Interplanetary Mission Planning

NASA Technical Reports Server (NTRS)

Englander, Jacob

2015-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. Because low-thrust trajectory design is tightly coupled with systems design, power and propulsion characteristics must be chosen as well. In addition, a time-history of control variables must be chosen which defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a multi-objective hybrid optimal control problem. The methods is demonstrated on hypothetical mission to the main asteroid belt and to Deimos.

Multi-Objective Hybrid Optimal Control for Interplanetary Mission Planning

NASA Technical Reports Server (NTRS)

Englander, Jacob A.

2014-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. Because low-thrust trajectory design is tightly coupled with systems design, power and propulsion characteristics must be chosen as well. In addition, a time-history of control variables must be chosen which defines the trajectory. There are often may thousands, if not millions, of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a multi-objective hybrid optimal control problem. The method is demonstrated on hypothetical mission to the main asteroid belt and to Deimos.

Distinct thermodynamic signatures of oligomer generation in the aggregation of the amyloid-β peptide

NASA Astrophysics Data System (ADS)

Cohen, Samuel I. A.; Cukalevski, Risto; Michaels, Thomas C. T.; Šarić, Andela; Törnquist, Mattias; Vendruscolo, Michele; Dobson, Christopher M.; Buell, Alexander K.; Knowles, Tuomas P. J.; Linse, Sara

2018-05-01

Mapping free-energy landscapes has proved to be a powerful tool for studying reaction mechanisms. Many complex biomolecular assembly processes, however, have remained challenging to access using this approach, including the aggregation of peptides and proteins into amyloid fibrils implicated in a range of disorders. Here, we generalize the strategy used to probe free-energy landscapes in protein folding to determine the activation energies and entropies that characterize each of the molecular steps in the aggregation of the amyloid-β peptide (Aβ42), which is associated with Alzheimer's disease. Our results reveal that interactions between monomeric Aβ42 and amyloid fibrils during fibril-dependent secondary nucleation fundamentally reverse the thermodynamic signature of this process relative to primary nucleation, even though both processes generate aggregates from soluble peptides. By mapping the energetic and entropic contributions along the reaction trajectories, we show that the catalytic efficiency of Aβ42 fibril surfaces results from the enthalpic stabilization of adsorbing peptides in conformations amenable to nucleation, resulting in a dramatic lowering of the activation energy for nucleation.

Distinct thermodynamic signatures of oligomer generation in the aggregation of the amyloid-β peptide.

PubMed

Cohen, Samuel I A; Cukalevski, Risto; Michaels, Thomas C T; Šarić, Anđela; Törnquist, Mattias; Vendruscolo, Michele; Dobson, Christopher M; Buell, Alexander K; Knowles, Tuomas P J; Linse, Sara

2018-05-01

Mapping free-energy landscapes has proved to be a powerful tool for studying reaction mechanisms. Many complex biomolecular assembly processes, however, have remained challenging to access using this approach, including the aggregation of peptides and proteins into amyloid fibrils implicated in a range of disorders. Here, we generalize the strategy used to probe free-energy landscapes in protein folding to determine the activation energies and entropies that characterize each of the molecular steps in the aggregation of the amyloid-β peptide (Aβ42), which is associated with Alzheimer's disease. Our results reveal that interactions between monomeric Aβ42 and amyloid fibrils during fibril-dependent secondary nucleation fundamentally reverse the thermodynamic signature of this process relative to primary nucleation, even though both processes generate aggregates from soluble peptides. By mapping the energetic and entropic contributions along the reaction trajectories, we show that the catalytic efficiency of Aβ42 fibril surfaces results from the enthalpic stabilization of adsorbing peptides in conformations amenable to nucleation, resulting in a dramatic lowering of the activation energy for nucleation.

Trajectories of Ethnic-Racial Identity and Autonomy Among Mexican-Origin Adolescent Mothers in the United States.

PubMed

Umaña-Taylor, Adriana J; Updegraff, Kimberly A; Jahromi, Laudan B; Zeiders, Katharine H

2015-01-01

This study examined trajectories of ethnic-racial identity (ERI) and autonomy development among Mexican-origin adolescent females in the United States (N = 181; M(age) at Wave 1 = 16.80 years, SD = 1.00) as they transitioned through the first 5 years of parenthood. Trajectories of ERI and autonomy also were examined in relation to psychosocial functioning. Unconditional latent growth models indicated significant growth in autonomy, ERI resolution, and ERI affirmation from middle to late adolescence. Conditional latent growth models indicated that autonomy and ERI exploration growth trajectories were positively associated with psychosocial adjustment. Although adolescent mothers are experiencing transitions that are not normative during adolescence, they also engage in normative developmental processes, and their engagement in such processes is linked with better adjustment. © 2015 The Authors. Child Development © 2015 Society for Research in Child Development, Inc.

Positive Youth Development and Resilience: Growth Patterns of Social Skills Among Youth Investigated for Maltreatment.

PubMed

Oshri, Assaf; Topple, Trasie A; Carlson, Matthew W

2017-07-01

Maltreated children are a vulnerable population, yet many of these youth follow positive developmental pathways. The primary aim was to identify social skills growth trajectories among at-risk youth to understand processes underlying resilience. Nationally representative, longitudinal data from 1,179 families investigated for child maltreatment (M age  = 12.75) were obtained from the National Survey of Child and Adolescent Well-Being. Four trajectories were identified-stress-resistant, emergent resilience, breakdown, and unresponsive-maladaptive. Protective resources from multiple levels of the youth ecology (individual, family, school, and social service) predicted positive growth social skills trajectories. Resilience process and attendant positive outcomes in multiple domains of functioning were evident among the stress-resistant and emergent resilience trajectories. Results underscore the saliency of social skills development for resilient outcomes in youth. © 2017 The Authors. Child Development © 2017 Society for Research in Child Development, Inc.

Multi-Objective Hybrid Optimal Control for Interplanetary Mission Planning

NASA Technical Reports Server (NTRS)

Englander, Jacob; Vavrina, Matthew; Ghosh, Alexander

2015-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed and in some cases the final destination. In addition, a time-history of control variables must be chosen which defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very diserable. This work presents such as an approach by posing the mission design problem as a multi-objective hybrid optimal control problem. The method is demonstrated on a hypothetical mission to the main asteroid belt.

Rapid Preliminary Design of Interplanetary Trajectories Using the Evolutionary Mission Trajectory Generator

NASA Technical Reports Server (NTRS)

Englander, Jacob

2016-01-01

Preliminary design of interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a hybrid optimal control problem. The method is demonstrated on notional high-thrust chemical and low-thrust electric propulsion missions. In the low-thrust case, the hybrid optimal control problem is augmented to include systems design optimization.

Social Connections, Trajectories of Hopelessness, and Serious Violence in Impoverished Urban Youth

PubMed Central

Stoddard, Sarah A.; Henly, Susan J.; Sieving, Renee E.; Bolland, John

2011-01-01

Youth living in impoverished urban neighborhoods are at risk for becoming hopeless about their future and engaging in violent behaviors. The current study seeks to examine the longitudinal relationship between social connections, hopelessness trajectories, and subsequent violent behavior across adolescence. Our sample included 723 (49% female) African American youth living in impoverished urban neighborhoods who participated in the Mobile Youth Survey from 1998 through 2006. Using general growth mixture modeling, we found two hopelessness trajectory classes for both boys and girls during middle adolescence: a consistently low hopelessness class and an increasingly hopeless class with quadratic change. In all classes, youth who reported stronger early adolescent connections to their mothers were less hopeless at age 13. The probability of later adolescent violence with a weapon was higher for boys and was associated with the increasingly hopeless class for both boys and girls. Implications for new avenues of research and design of hope-based prevention interventions will be discussed. PMID:20690037

Improvement of operational prediction system applied to the oil spill prediction in the Yellow Sea

NASA Astrophysics Data System (ADS)

Kim, C.; Cho, Y.; Choi, B.; Jung, K.

2012-12-01

Multi-nested operational prediction system for the Yellow Sea (YS) has been developed to predict the movement of oil spill. Drifter trajectory simulations were performed to predict the path of the oil spill of the MV Hebei Spirit accident occurred on 7 December 2007. The oil spill trajectories at the surface predicted by numerical model without tidal forcing were remarkably faster than the observation. However the speed of drifters predicted by model considering tide was satisfactorily improved not only for the motion with tidal cycle but also for the motion with subtidal period. The subtidal flow of the simulation with tide was weaker than that without tide due to tidal stress. Tidal stress decelerated the southward subtidal flows driven by northwesterly wind along the Korean coast of the YS in winter. This result provides a substantial implication that tide must be included for accurate prediction of oil spill trajectory not only for variation within a tidal cycle but also for longer time scale advection in tide dominant area.

A Longitudinal Examination of Early Adolescence Ethnic Identity Trajectories

PubMed Central

Huang, Cindy Y.; Stormshak, Elizabeth A.

2011-01-01

Early adolescence is marked by transitions for adolescents, and is also a time for identity exploration. Ethnic identity is an essential component of youths’ sense of self. In this study we examined the trajectories of ethnic identity for adolescents from ethnic minority backgrounds during a 4-year period. Six latent class trajectories were identified in the study: the majority of adolescents (41.8%) displayed growth in ethnic identity over 4 years, followed by 30.1% whose high levels of ethnic identity remained stable, then by those who experienced moderate decreases in ethnic identity (10.8 percent). Another class of adolescents (7.3%) showed significant declines in ethnic identity level, followed by 5.5% of adolescents with significant increases, and finally by 4.5% of adolescents with low stable levels of ethnic identity during this developmental period. The classes differed by ethnicity, and adolescents with increasing high levels of ethnic identity reported better parent–child relationships. Findings and implications are discussed. PMID:21787058

Parent–Child Conflict and Early Childhood Adjustment in Two-Parent Low-Income Families: Parallel Developmental Processes

PubMed Central

Shaw, Daniel S.; Crossan, Jennifer L.; Dishion, Thomas J.; Wilson, Melvin N.

2015-01-01

Parent–child conflict is central to most intervention models focused on reducing child problem behavior, yet few longitudinal studies have examined these processes during early childhood. The current study investigates (1) growth in mother–child and father figure (FF)–child conflict, (2) associations between trajectories of mother–child and FF–child conflict and children’s adjustment; and (3) intervention effects in attenuating conflict. Participants are 195 ethnically diverse mother–FF–child triads drawn from a larger parenting intervention study for families with children at risk for developing conduct problems. Mother–child conflict decreased from ages 2 to 4, but decreases were unrelated to changes in children’s adjustment problems. In contrast, the slope of FF–child conflict was positively related to the slope of child externalizing behaviors. Random assignment to a family-centered parenting intervention predicted rate of decline in mother–child conflict. Findings are discussed with respect to developmental patterns of parent–child conflict in early childhood and implications for prevention. PMID:24610382

"From that moment on my life changed": turning points in the healing process for men recovering from child sexual abuse.

PubMed

Easton, Scott D; Leone-Sheehan, Danielle M; Sophis, Ellen J; Willis, Danny G

2015-01-01

Recent research indicates that child sexual abuse often undermines the health of boys and men across the lifespan. However, some male survivors experience a turning point marking a positive change in their health trajectories and healing process. Although frequently discussed in reference to physical health problems or addictions, very little is known about turning points with respect to child sexual abuse for men. The purpose of this secondary qualitative analysis was to describe the different types of turning points experienced by male survivors who completed the 2010 Health and Well-Being Survey (N = 250). Using conventional content analysis, researchers identified seven types of turning points that were classified into three broad categories: influential relationships (professional and group support, personal relationships), insights and new meanings (cognitive realizations, necessity to change, spiritual transformation), and action-oriented communication (disclosure of CSA, pursuit of justice). Implications for clinical practice and future research are discussed.

Trajectory Dispersed Vehicle Process for Space Launch System

NASA Technical Reports Server (NTRS)

Statham, Tamara; Thompson, Seth

2017-01-01

The Space Launch System (SLS) vehicle is part of NASA's deep space exploration plans that includes manned missions to Mars. Manufacturing uncertainties in design parameters are key considerations throughout SLS development as they have significant effects on focus parameters such as lift-off-thrust-to-weight, vehicle payload, maximum dynamic pressure, and compression loads. This presentation discusses how the SLS program captures these uncertainties by utilizing a 3 degree of freedom (DOF) process called Trajectory Dispersed (TD) analysis. This analysis biases nominal trajectories to identify extremes in the design parameters for various potential SLS configurations and missions. This process utilizes a Design of Experiments (DOE) and response surface methodologies (RSM) to statistically sample uncertainties, and develop resulting vehicles using a Maximum Likelihood Estimate (MLE) process for targeting uncertainties bias. These vehicles represent various missions and configurations which are used as key inputs into a variety of analyses in the SLS design process, including 6 DOF dispersions, separation clearances, and engine out failure studies.

Surface modifications with Lissajous trajectories using atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Wei; Yao, Nan, E-mail: nyao@princeton.edu

2015-09-14

In this paper, we report a method for atomic force microscopy surface modifications with single-tone and multiple-resolution Lissajous trajectories. The tip mechanical scratching experiments with two series of Lissajous trajectories were carried out on monolayer films. The scratching processes with two scan methods have been illustrated. As an application, the tip-based triboelectrification phenomenon on the silicon dioxide surface with Lissajous trajectories was investigated. The triboelectric charges generated within the tip rubbed area on the surface were characterized in-situ by scanning Kelvin force microscopy. This method would provide a promising and cost-effective approach for surface modifications and nanofabrication.

Trajectory Design Tools for Libration and Cis-Lunar Environments

NASA Technical Reports Server (NTRS)

Folta, David C.; Webster, Cassandra M.; Bosanac, Natasha; Cox, Andrew; Guzzetti, Davide; Howell, Kathleen C.

2016-01-01

Innovative trajectory design tools are required to support challenging multi-body regimes with complex dynamics, uncertain perturbations, and the integration of propulsion influences. Two distinctive tools, Adaptive Trajectory Design and the General Mission Analysis Tool have been developed and certified to provide the astrodynamics community with the ability to design multi-body trajectories. In this paper we discuss the multi-body design process and the capabilities of both tools. Demonstrable applications to confirmed missions, the Lunar IceCube Cubesat lunar mission and the Wide-Field Infrared Survey Telescope (WFIRST) Sun-Earth L2 mission, are presented.

Determining Individual Variation in Growth and Its Implication for Life-History and Population Processes Using the Empirical Bayes Method

PubMed Central

Vincenzi, Simone; Mangel, Marc; Crivelli, Alain J.; Munch, Stephan; Skaug, Hans J.

2014-01-01

The differences in demographic and life-history processes between organisms living in the same population have important consequences for ecological and evolutionary dynamics. Modern statistical and computational methods allow the investigation of individual and shared (among homogeneous groups) determinants of the observed variation in growth. We use an Empirical Bayes approach to estimate individual and shared variation in somatic growth using a von Bertalanffy growth model with random effects. To illustrate the power and generality of the method, we consider two populations of marble trout Salmo marmoratus living in Slovenian streams, where individually tagged fish have been sampled for more than 15 years. We use year-of-birth cohort, population density during the first year of life, and individual random effects as potential predictors of the von Bertalanffy growth function's parameters k (rate of growth) and (asymptotic size). Our results showed that size ranks were largely maintained throughout marble trout lifetime in both populations. According to the Akaike Information Criterion (AIC), the best models showed different growth patterns for year-of-birth cohorts as well as the existence of substantial individual variation in growth trajectories after accounting for the cohort effect. For both populations, models including density during the first year of life showed that growth tended to decrease with increasing population density early in life. Model validation showed that predictions of individual growth trajectories using the random-effects model were more accurate than predictions based on mean size-at-age of fish. PMID:25211603

Anterior Cortical Development During Adolescence in Bipolar Disorder.

PubMed

Najt, Pablo; Wang, Fei; Spencer, Linda; Johnston, Jennifer A Y; Cox Lippard, Elizabeth T; Pittman, Brian P; Lacadie, Cheryl; Staib, Lawrence H; Papademetris, Xenophon; Blumberg, Hilary P

2016-02-15

Increasing evidence supports a neurodevelopmental model for bipolar disorder (BD), with adolescence as a critical period in its development. Developmental abnormalities of anterior paralimbic and heteromodal frontal cortices, key structures in emotional regulation processes and central in BD, are implicated. However, few longitudinal studies have been conducted, limiting understanding of trajectory alterations in BD. In this study, we performed longitudinal neuroimaging of adolescents with and without BD and assessed volume changes over time, including changes in tissue overall and within gray and white matter. Larger decreases over time in anterior cortical volumes in the adolescents with BD were hypothesized. Gray matter decreases and white matter increases are typically observed during adolescence in anterior cortices. It was hypothesized that volume decreases over time in BD would reflect alterations in those processes, showing larger gray matter contraction and decreased white matter expansion. Two high-resolution magnetic resonance imaging scans were obtained approximately 2 years apart for 35 adolescents with bipolar I disorder (BDI) and 37 healthy adolescents. Differences over time between groups were investigated for volume overall and specifically for gray and white matter. Relative to healthy adolescents, adolescents with BDI showed greater volume contraction over time in a region including insula and orbitofrontal, rostral, and dorsolateral prefrontal cortices (p < .05, corrected), including greater gray matter contraction and decreased white matter expansion over time, in the BD compared with the healthy group. The findings support neurodevelopmental abnormalities during adolescence in BDI in anterior cortices, including altered developmental trajectories of anterior gray and white matter. Published by Elsevier Inc.

Windfield and trajectory models for tornado-propelled objects. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redmann, G.H.; Radbill, J.R.; Marte, J.E.

1983-03-01

This is the final report of a three-phased research project to develop a six-degree-of-freedom mathematical model to predict the trajectories of tornado-propelled objects. The model is based on the meteorological, aerodynamic, and dynamic processes that govern the trajectories of missiles in a tornadic windfield. The aerodynamic coefficients for the postulated missiles were obtained from full-scale wind tunnel tests on a 12-inch pipe and car and from drop tests. Rocket sled tests were run whereby the 12-inch pipe and car were injected into a worst-case tornado windfield in order to verify the trajectory model. To simplify and facilitate the use ofmore » the trajectory model for design applications without having to run the computer program, this report gives the trajectory data for NRC-postulated missiles in tables based on given variables of initial conditions of injection and tornado windfield. Complete descriptions of the tornado windfield and trajectory models are presented. The trajectory model computer program is also included for those desiring to perform trajectory or sensitivity analyses beyond those included in the report or for those wishing to examine other missiles and use other variables.« less

Sex Differences in the Implications of Partner Physical Attractiveness for the Trajectory of Marital Satisfaction

PubMed Central

Meltzer, Andrea L.; McNulty, James K.; Jackson, Grace; Karney, Benjamin R.

2014-01-01

Do men value physical attractiveness in a mate more than women? Scientists in numerous disciplines believe that they do, but recent research using speed-dating paradigms suggests that males and females are equally influenced by physical attractiveness when choosing potential mates. Nevertheless, the premise of the current work is that sex differences in the importance of physical attractiveness are most likely to emerge in research on long-term relationships. Accordingly, the current work drew from four independent, longitudinal studies to examine sex differences in the implications of partner physical attractiveness for trajectories of marital satisfaction. In all four studies, both partners’ physical attractiveness was objectively rated at baseline and both partners reported their marital satisfaction up to eight times over the first four years of marriage. Whereas husbands were more satisfied at the beginning of the marriage and remained more satisfied over the next four years to the extent that they had an attractive wife, wives were no more or less satisfied initially or over the next four years to the extent that they had an attractive husband. Most importantly, a direct test indicated that partner physical attractiveness played a larger role in predicting husbands’ satisfaction than predicting wives’ satisfaction. These findings strengthen support for the idea that gender differences in self-reported preferences for physical attractiveness do have implications for long-term relationship outcomes. PMID:24128188

Monte Carlo Analysis as a Trajectory Design Driver for the TESS Mission

NASA Technical Reports Server (NTRS)

Nickel, Craig; Lebois, Ryan; Lutz, Stephen; Dichmann, Donald; Parker, Joel

2016-01-01

The Transiting Exoplanet Survey Satellite (TESS) will be injected into a highly eccentric Earth orbit and fly 3.5 phasing loops followed by a lunar flyby to enter a mission orbit with lunar 2:1 resonance. Through the phasing loops and mission orbit, the trajectory is significantly affected by lunar and solar gravity. We have developed a trajectory design to achieve the mission orbit and meet mission constraints, including eclipse avoidance and a 30-year geostationary orbit avoidance requirement. A parallelized Monte Carlo simulation was performed to validate the trajectory after injecting common perturbations, including launch dispersions, orbit determination errors, and maneuver execution errors. The Monte Carlo analysis helped identify mission risks and is used in the trajectory selection process.

Probabilistic Modeling of Aircraft Trajectories for Dynamic Separation Volumes

NASA Technical Reports Server (NTRS)

Lewis, Timothy A.

2016-01-01

With a proliferation of new and unconventional vehicles and operations expected in the future, the ab initio airspace design will require new approaches to trajectory prediction for separation assurance and other air traffic management functions. This paper presents an approach to probabilistic modeling of the trajectory of an aircraft when its intent is unknown. The approach uses a set of feature functions to constrain a maximum entropy probability distribution based on a set of observed aircraft trajectories. This model can be used to sample new aircraft trajectories to form an ensemble reflecting the variability in an aircraft's intent. The model learning process ensures that the variability in this ensemble reflects the behavior observed in the original data set. Computational examples are presented.

Convergence analysis of sliding mode trajectories in multi-objective neural networks learning.

PubMed

Costa, Marcelo Azevedo; Braga, Antonio Padua; de Menezes, Benjamin Rodrigues

2012-09-01

The Pareto-optimality concept is used in this paper in order to represent a constrained set of solutions that are able to trade-off the two main objective functions involved in neural networks supervised learning: data-set error and network complexity. The neural network is described as a dynamic system having error and complexity as its state variables and learning is presented as a process of controlling a learning trajectory in the resulting state space. In order to control the trajectories, sliding mode dynamics is imposed to the network. It is shown that arbitrary learning trajectories can be achieved by maintaining the sliding mode gains within their convergence intervals. Formal proofs of convergence conditions are therefore presented. The concept of trajectory learning presented in this paper goes further beyond the selection of a final state in the Pareto set, since it can be reached through different trajectories and states in the trajectory can be assessed individually against an additional objective function. Copyright © 2012 Elsevier Ltd. All rights reserved.

Referent control and motor equivalence of reaching from standing

PubMed Central

Tomita, Yosuke; Feldman, Anatol G.

2016-01-01

Motor actions may result from central changes in the referent body configuration, defined as the body posture at which muscles begin to be activated or deactivated. The actual body configuration deviates from the referent configuration, particularly because of body inertia and environmental forces. Within these constraints, the system tends to minimize the difference between these configurations. For pointing movement, this strategy can be expressed as the tendency to minimize the difference between the referent trajectory (RT) and actual trajectory (QT) of the effector (hand). This process may underlie motor equivalent behavior that maintains the pointing trajectory regardless of the number of body segments involved. We tested the hypothesis that the minimization process is used to produce pointing in standing subjects. With eyes closed, 10 subjects reached from a standing position to a remembered target located beyond arm length. In randomly chosen trials, hip flexion was unexpectedly prevented, forcing subjects to take a step during pointing to prevent falling. The task was repeated when subjects were instructed to intentionally take a step during pointing. In most cases, reaching accuracy and trajectory curvature were preserved due to adaptive condition-specific changes in interjoint coordination. Results suggest that referent control and the minimization process associated with it may underlie motor equivalence in pointing. NEW & NOTEWORTHY Motor actions may result from minimization of the deflection of the actual body configuration from the centrally specified referent body configuration, in the limits of neuromuscular and environmental constraints. The minimization process may maintain reaching trajectory and accuracy regardless of the number of body segments involved (motor equivalence), as confirmed in this study of reaching from standing in young healthy individuals. Results suggest that the referent control process may underlie motor equivalence in reaching. PMID:27784802

Lunar Cube Transfer Trajectory Options

NASA Technical Reports Server (NTRS)

Folta, David; Dichmann, Donald James; Clark, Pamela E.; Haapala, Amanda; Howell, Kathleen

2015-01-01

Numerous Earth-Moon trajectory and lunar orbit options are available for Cubesat missions. Given the limited Cubesat injection infrastructure, transfer trajectories are contingent upon the modification of an initial condition of the injected or deployed orbit. Additionally, these transfers can be restricted by the selection or designs of Cubesat subsystems such as propulsion or communication. Nonetheless, many trajectory options can b e considered which have a wide range of transfer duration, fuel requirements, and final destinations. Our investigation of potential trajectories highlights several options including deployment from low Earth orbit (LEO) geostationary transfer orbits (GTO) and higher energy direct lunar transfer and the use of longer duration Earth-Moon dynamical systems. For missions with an intended lunar orbit, much of the design process is spent optimizing a ballistic capture while other science locations such as Sun-Earth libration or heliocentric orbits may simply require a reduced Delta-V imparted at a convenient location along the trajectory.

Lunar Cube Transfer Trajectory Options

NASA Technical Reports Server (NTRS)

Folta, David; Dichmann, Donald J.; Clark, Pamela; Haapala, Amanda; Howell, Kathleen

2015-01-01

Numerous Earth-Moon trajectory and lunar orbit options are available for Cubesat missions. Given the limited Cubesat injection infrastructure, transfer trajectories are contingent upon the modification of an initial condition of the injected or deployed orbit. Additionally, these transfers can be restricted by the selection or designs of Cubesat subsystems such as propulsion or communication. Nonetheless, many trajectory options can be considered which have a wide range of transfer durations, fuel requirements, and final destinations. Our investigation of potential trajectories highlights several options including deployment from low Earth orbit (LEO), geostationary transfer orbits (GTO), and higher energy direct lunar transfers and the use of longer duration Earth-Moon dynamical systems. For missions with an intended lunar orbit, much of the design process is spent optimizing a ballistic capture while other science locations such as Sun-Earth libration or heliocentric orbits may simply require a reduced Delta-V imparted at a convenient location along the trajectory.

Optimization of Insertion Cost for Transfer Trajectories to Libration Point Orbits

NASA Technical Reports Server (NTRS)

Howell, K. C.; Wilson, R. S.; Lo, M. W.

1999-01-01

The objective of this work is the development of efficient techniques to optimize the cost associated with transfer trajectories to libration point orbits in the Sun-Earth-Moon four body problem, that may include lunar gravity assists. Initially, dynamical systems theory is used to determine invariant manifolds associated with the desired libration point orbit. These manifolds are employed to produce an initial approximation to the transfer trajectory. Specific trajectory requirements such as, transfer injection constraints, inclusion of phasing loops, and targeting of a specified state on the manifold are then incorporated into the design of the transfer trajectory. A two level differential corrections process is used to produce a fully continuous trajectory that satisfies the design constraints, and includes appropriate lunar and solar gravitational models. Based on this methodology, and using the manifold structure from dynamical systems theory, a technique is presented to optimize the cost associated with insertion onto a specified libration point orbit.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heslar, John; Chu, Shih-I.

Recently, the study of near- and below- threshold regime harmonics as a potential source of intense coherent vacuum-ultraviolet radiation has received considerable attention. However, the dynamical origin of these lower harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here we perform the first fully ab initio and high precision 3D quantum study of the below- and near-threshold harmonic generation of H 2 + molecules in an intense 800-nm near-infrared (NIR) laser field. Furthermore, combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, we explore in-depth the roles of various quantummore » trajectories, including short- and long trajectories, multiphoton trajectories, resonance-enhanced trajectories, and multiple rescattering trajectories of the below- and near- threshold harmonic generation processes. Our results shed new light on the dynamical origin of the below- and near-threshold harmonic generation and various quantum trajectories for diatomic molecules for the first time.« less

Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 2: Programmer's manual

NASA Technical Reports Server (NTRS)

Byrnes, D. V.; Carney, P. C.; Underwood, J. W.; Vogt, E. D.

1974-01-01

The six month effort was responsible for the development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs. The program NOMNAL targets a transfer trajectory from earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty.

Theoretical Studies in Chemical Kinetics - Annual Report, 1970.

DOE R&D Accomplishments Database

Karplus, Martin

1970-10-01

The research performed includes (a) Alkali-Halide, Alkali-Halide (MX, M?X?) Exchange Reactions; (b) Inversion Problem; (c) Quantum Mechanics of Scattering Processes, (d) Transition State Analysis of Classical Trajectories, (e) Differential Cross Sections from Classical Trajectories; and (f) Other Studies.

Envisioning future cognitive telerehabilitation technologies: a co-design process with clinicians.

PubMed

How, Tuck-Voon; Hwang, Amy S; Green, Robin E A; Mihailidis, Alex

2017-04-01

Purpose Cognitive telerehabilitation is the concept of delivering cognitive assessment, feedback, or therapeutic intervention at a distance through technology. With the increase of mobile devices, wearable sensors, and novel human-computer interfaces, new possibilities are emerging to expand the cognitive telerehabilitation paradigm. This research aims to: (1) explore design opportunities and considerations when applying emergent pervasive computing technologies to cognitive telerehabilitation and (2) develop a generative co-design process for use with rehabilitation clinicians. Methods We conducted a custom co-design process that used design cards, probes, and design sessions with traumatic brain injury (TBI) clinicians. All field notes and transcripts were analyzed qualitatively. Results Potential opportunities for TBI cognitive telerehabilitation exist in the areas of communication competency, executive functioning, emotional regulation, energy management, assessment, and skill training. Designers of TBI cognitive telerehabilitation technologies should consider how technologies are adapted to a patient's physical/cognitive/emotional state, their changing rehabilitation trajectory, and their surrounding life context (e.g. social considerations). Clinicians were receptive to our co-design approach. Conclusion Pervasive computing offers new opportunities for life-situated cognitive telerehabilitation. Convivial design methods, such as this co-design process, are a helpful way to explore new design opportunities and an important space for further methodological development. Implications for Rehabilitation Designers of rehabilitation technologies should consider how to extend current design methods in order to facilitate the creative contribution of rehabilitation stakeholders. This co-design approach enables a fuller participation from rehabilitation clinicians at the front-end of design. Pervasive computing has the potential to: extend the duration and intensity of cognitive telerehabilitation training (including the delivery of 'booster' sessions or maintenance therapies); provide assessment and treatment in the context of a traumatic brain injury (TBI) patient's everyday life (thereby enhancing generalization); and permit time-sensitive interventions. Long-term use of pervasive computing for TBI cognitive telerehabilitation should take into account a patient's changing recovery trajectory, their meaningful goals, and their journey from loss to redefinition.

Estimating trajectories of energy intake through childhood and adolescence using linear-spline multilevel models.

PubMed

Anderson, Emma L; Tilling, Kate; Fraser, Abigail; Macdonald-Wallis, Corrie; Emmett, Pauline; Cribb, Victoria; Northstone, Kate; Lawlor, Debbie A; Howe, Laura D

2013-07-01

Methods for the assessment of changes in dietary intake across the life course are underdeveloped. We demonstrate the use of linear-spline multilevel models to summarize energy-intake trajectories through childhood and adolescence and their application as exposures, outcomes, or mediators. The Avon Longitudinal Study of Parents and Children assessed children's dietary intake several times between ages 3 and 13 years, using both food frequency questionnaires (FFQs) and 3-day food diaries. We estimated energy-intake trajectories for 12,032 children using linear-spline multilevel models. We then assessed the associations of these trajectories with maternal body mass index (BMI), and later offspring BMI, and also their role in mediating the relation between maternal and offspring BMIs. Models estimated average and individual energy intake at 3 years, and linear changes in energy intake from age 3 to 7 years and from age 7 to 13 years. By including the exposure (in this example, maternal BMI) in the multilevel model, we were able to estimate the average energy-intake trajectories across levels of the exposure. When energy-intake trajectories are the exposure for a later outcome (in this case offspring BMI) or a mediator (between maternal and offspring BMI), results were similar, whether using a two-step process (exporting individual-level intercepts and slopes from multilevel models and using these in linear regression/path analysis), or a single-step process (multivariate multilevel models). Trajectories were similar when FFQs and food diaries were assessed either separately, or when combined into one model. Linear-spline multilevel models provide useful summaries of trajectories of dietary intake that can be used as an exposure, outcome, or mediator.

Motivational Trajectories for Early Language Learning across the Primary-Secondary School Transition

ERIC Educational Resources Information Center

Graham, Suzanne; Courtney, Louise; Tonkyn, Alan; Marinis, Theodoros

2016-01-01

The transition from primary to secondary school is an area of concern across a range of curriculum subjects and this is no less so for foreign language learning. Indeed problems with transition have been identified in England as an important barrier to the introduction of language learning to the primary school curriculum, with implications for…

Contesting the Neoliberal Project for Agriculture: Productivist and Multifunctional Trajectories in the European Union and Australia

ERIC Educational Resources Information Center

Dibden, Jacqui; Potter, Clive; Cocklin, Chris

2009-01-01

The liberalisation of agricultural trade is strongly contested as an international policy project. In the context of the current World Trade Organisation (WTO) Doha trade round, concerns revolve around the implications of freer trade for rural livelihoods and environments. Analysis of this complex and morally charged issue offers important…

Career Development Issues in the Former USSR: Implications of Political Changes for Personal Career Development

ERIC Educational Resources Information Center

Yakushko, Oksana

2007-01-01

This article addresses the distinctive aspects of career development of people from the former Union of Soviet Socialist Republics (USSR). The ecological model of career development is applied to understanding how political changes can influence the career trajectories of individuals within a culture. The role of the political, social, familial,…

Equivalence principles and electromagnetism

NASA Technical Reports Server (NTRS)

Ni, W.-T.

1977-01-01

The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

A Panel Data Investigation of the Relationship between Graduate Job Search and Employment Outcomes

ERIC Educational Resources Information Center

Carroll, David

2013-01-01

The transition from study to work is an important one. The jobs that graduates secure after completing their studies may very well shape the trajectory of their future careers, so an understanding of how job search influences employment outcomes has significant implications for theory and higher education practice. This article specifically…

Analysis of Factors and Implications Influencing Leadership Ascension of Female Athletic Directors in Intercollegiate Athletics

ERIC Educational Resources Information Center

Burney, Rolanda C.

2010-01-01

This narrative analysis/life story study was designed to understand the factors influencing the career trajectory of female athletic directors in National Collegiate Athletic Association affiliated institutions and to discover how those factors functioned as a road map for future female administrators. Both social role and role congruity theories…

On the formation of dense understory layers in forests worldwide: consequences and implications for forest dynamics, biodiversity, and succession

Treesearch

Alejandro A. Royo; Walter P. Carson

2006-01-01

The mechanistic basis underpinning forest succession is the gap-phase paradigm in which overstory disturbance interacts with seedling and sapling shade tolerance to determine successional trajectories. The theory, and ensuing simulation models, typically assume that understory plants have little impact on the advance regeneration layer's composition. We challenge...

The Development of Stranger Fear in Infancy and Toddlerhood: Normative Development, Individual Differences, Antecedents, and Outcomes

ERIC Educational Resources Information Center

Brooker, Rebecca J.; Buss, Kristin A.; Lemery-Chalfant, Kathryn; Aksan, Nazan; Davidson, Richard J.; Goldsmith, H. Hill

2013-01-01

Despite implications that stranger fear is an important aspect of developing behavioral inhibition, a known risk factor for anxiety, normative and atypical developmental trajectories of stranger fear across infancy and toddlerhood remain understudied. We used a large, longitudinal data set (N = 1285) including multi-trait, multi-method assessments…

The decay of highly excited open strings

NASA Technical Reports Server (NTRS)

Mitchell, D.; Turok, N.; Wilkinson, R.; Jetzer, P.

1988-01-01

The decay rates of leading edge Regge trajectory states are calculated for very high level number in open bosonic string theories, ignoring tachyon final states. The optical theorem simplifies the analysis while enabling identification of the different mass level decay channels. The main result is that (in four dimensions) the greatest single channel is the emission of a single photon and a state of the next mass level down. A simple asymptotic formula for arbitrarily high level number is given for this process. Also calculated is the total decay rate exactly up to N=100. It shows little variation over this range but appears to decrease for larger N. The formalism is checked in examples and the decay rate of the first excited level calculated for open superstring theories. The calculation may also have implications for high spin meson resonances.

The Mechanism for Processing Random-Dot Motion at Various Speeds in Early Visual Cortices

PubMed Central

An, Xu; Gong, Hongliang; McLoughlin, Niall; Yang, Yupeng; Wang, Wei

2014-01-01

All moving objects generate sequential retinotopic activations representing a series of discrete locations in space and time (motion trajectory). How direction-selective neurons in mammalian early visual cortices process motion trajectory remains to be clarified. Using single-cell recording and optical imaging of intrinsic signals along with mathematical simulation, we studied response properties of cat visual areas 17 and 18 to random dots moving at various speeds. We found that, the motion trajectory at low speed was encoded primarily as a direction signal by groups of neurons preferring that motion direction. Above certain transition speeds, the motion trajectory is perceived as a spatial orientation representing the motion axis of the moving dots. In both areas studied, above these speeds, other groups of direction-selective neurons with perpendicular direction preferences were activated to encode the motion trajectory as motion-axis information. This applied to both simple and complex neurons. The average transition speed for switching between encoding motion direction and axis was about 31°/s in area 18 and 15°/s in area 17. A spatio-temporal energy model predicted the transition speeds accurately in both areas, but not the direction-selective indexes to random-dot stimuli in area 18. In addition, above transition speeds, the change of direction preferences of population responses recorded by optical imaging can be revealed using vector maximum but not vector summation method. Together, this combined processing of motion direction and axis by neurons with orthogonal direction preferences associated with speed may serve as a common principle of early visual motion processing. PMID:24682033

Prediction processes during multiple object tracking (MOT): involvement of dorsal and ventral premotor cortices

PubMed Central

Atmaca, Silke; Stadler, Waltraud; Keitel, Anne; Ott, Derek V M; Lepsien, Jöran; Prinz, Wolfgang

2013-01-01

Background The multiple object tracking (MOT) paradigm is a cognitive task that requires parallel tracking of several identical, moving objects following nongoal-directed, arbitrary motion trajectories. Aims The current study aimed to investigate the employment of prediction processes during MOT. As an indicator for the involvement of prediction processes, we targeted the human premotor cortex (PM). The PM has been repeatedly implicated to serve the internal modeling of future actions and action effects, as well as purely perceptual events, by means of predictive feedforward functions. Materials and methods Using functional magnetic resonance imaging (fMRI), BOLD activations recorded during MOT were contrasted with those recorded during the execution of a cognitive control task that used an identical stimulus display and demanded similar attentional load. A particular effort was made to identify and exclude previously found activation in the PM-adjacent frontal eye fields (FEF). Results We replicated prior results, revealing occipitotemporal, parietal, and frontal areas to be engaged in MOT. Discussion The activation in frontal areas is interpreted to originate from dorsal and ventral premotor cortices. The results are discussed in light of our assumption that MOT engages prediction processes. Conclusion We propose that our results provide first clues that MOT does not only involve visuospatial perception and attention processes, but prediction processes as well. PMID:24363971

Adverse trajectories of mental health problems predict subsequent burnout and work-family conflict - a longitudinal study of employed women with children followed over 18 years.

PubMed

Nilsen, Wendy; Skipstein, Anni; Demerouti, Evangelia

2016-11-08

The long-term consequence of experiencing mental health problems may lead to several adverse outcomes. The current study aims to validate previous identified trajectories of mental health problems from 1993 to 2006 in women by examining their implications on subsequent work and family-related outcomes in 2011. Employed women (n = 439) with children were drawn from the Tracking Opportunities and Problems-Study (TOPP), a community-based longitudinal study following Norwegian families across 18 years. Previous identified latent profiles of mental health trajectories (i.e., High; Moderate; Low-rising and Low levels of mental health problems over time) measured at six time points between 1993 and 2006 were examined as predictors of burnout (e.g., exhaustion and disengagement from work) and work-family conflict in 2011 in univariate and multivariate analyses of variance adjusted for potential confounders (age, job demands, and negative emotionality). We found that having consistently High and Moderate symptoms as well as Low-Rising symptoms from 1993 to 2006 predicted higher levels of exhaustion, disengagement from work and work-family conflict in 2011. Findings remained unchanged when adjusting for several potential confounders, but when adjusting for current mental health problems only levels of exhaustion were predicted by the mental health trajectories. The study expands upon previous studies on the field by using a longer time span and by focusing on employed women with children who experience different patterns of mental health trajectories. The long-term effect of these trajectories highlight and validate the importance of early identification and prevention in women experiencing adverse patterns of mental health problems with regards to subsequent work and family-related outcomes.

You Can't Think and Hit at the Same Time: Neural Correlates of Baseball Pitch Classification.

PubMed

Sherwin, Jason; Muraskin, Jordan; Sajda, Paul

2012-01-01

Hitting a baseball is often described as the most difficult thing to do in sports. A key aptitude of a good hitter is the ability to determine which pitch is coming. This rapid decision requires the batter to make a judgment in a fraction of a second based largely on the trajectory and spin of the ball. When does this decision occur relative to the ball's trajectory and is it possible to identify neural correlates that represent how the decision evolves over a split second? Using single-trial analysis of electroencephalography (EEG) we address this question within the context of subjects discriminating three types of pitches (fastball, curveball, slider) based on pitch trajectories. We find clear neural signatures of pitch classification and, using signal detection theory, we identify the times of discrimination on a trial-to-trial basis. Based on these neural signatures we estimate neural discrimination distributions as a function of the distance the ball is from the plate. We find all three pitches yield unique distributions, namely the timing of the discriminating neural signatures relative to the position of the ball in its trajectory. For instance, fastballs are discriminated at the earliest points in their trajectory, relative to the two other pitches, which is consistent with the need for some constant time to generate and execute the motor plan for the swing (or inhibition of the swing). We also find incorrect discrimination of a pitch (errors) yields neural sources in Brodmann Area 10, which has been implicated in prospective memory, recall, and task difficulty. In summary, we show that single-trial analysis of EEG yields informative distributions of the relative point in a baseball's trajectory when the batter makes a decision on which pitch is coming.

Teacher performance goal practices and elementary students’ behavioral engagement: A developmental perspective

PubMed Central

Hughes, Jan N.; Wu, Wei; West, Stephen G.

2010-01-01

We investigated growth trajectories for classroom performance goal practices and for student behavioral engagement across grades 2 to 5 for 497 academically at-risk elementary students. This study is the first longitudinal investigation of performance goal practices in the early elementary years. On average, teacher use of performance goal practices increased and students’ behavioral engagement declined across the four years. Using autoregressive latent trajectory (ALT) models, we examined the synchronous relations between teacher-reported performance goal practices and teacher-reported student behavioral engagement. As expected, as students move into classrooms with a new teacher with less emphasis on performance goal practices, they become more behaviorally engaged in school. Gender did not moderate these results. Implications for teacher professional development are discussed. PMID:21215834

Growth Trajectories of Mexican-Origin Adolescent Mothers’ Educational Expectations

PubMed Central

Bravo, Diamond Y.; Toomey, Russell B.; Umaña-Taylor, Adriana J.; Updegraff, Kimberly A.; Jahromi, Laudan B.

2015-01-01

Pregnant and parenting adolescents are at significant risk for educational underachievement. Educational expectations play a critical role for understanding subsequent educational attainment; yet, limited empirical attention has been given to changes in educational expectations across the transition to parenthood among adolescent mothers. This longitudinal study explored stability and change in educational expectations across the transition to parenthood among 191 first-time pregnant Mexican-origin adolescents (Mage = 16.76, SD = .98). The current study also examined how several contextually relevant risk and protective factors were associated with differential patterns of educational trajectories across this transition and subsequent educational attainment. Latent class growth analyses revealed three educational expectation trajectories: low and stable (< high school degree), moderate and increasing (≈ associate degree), and high and increasing (≈ bachelor’s degree). Adolescent mothers in the low and stable group encountered several educational risk factors that partially explained their probability of membership in this trajectory and subsequent lower attainment. Conversely, probability of membership in the high and increasing expectations class was partially explained by adolescents’ on-track school status at the time of pregnancy and their mother figures’ educational expectations for their pregnant daughters. These findings have implications for understanding the malleable factors that help to explain why some adolescent mothers describe consistently high educational expectations and subsequent higher attainment, while others do not. PMID:28392610

Monte Carlo Analysis as a Trajectory Design Driver for the Transiting Exoplanet Survey Satellite (TESS) Mission

NASA Technical Reports Server (NTRS)

Nickel, Craig; Parker, Joel; Dichmann, Don; Lebois, Ryan; Lutz, Stephen

2016-01-01

The Transiting Exoplanet Survey Satellite (TESS) will be injected into a highly eccentric Earth orbit and fly 3.5 phasing loops followed by a lunar flyby to enter a mission orbit with lunar 2:1 resonance. Through the phasing loops and mission orbit, the trajectory is significantly affected by lunar and solar gravity. We have developed a trajectory design to achieve the mission orbit and meet mission constraints, including eclipse avoidance and a 30-year geostationary orbit avoidance requirement. A parallelized Monte Carlo simulation was performed to validate the trajectory after injecting common perturbations, including launch dispersions, orbit determination errors, and maneuver execution errors. The Monte Carlo analysis helped identify mission risks and is used in the trajectory selection process.

Oceanic Flights and Airspace: Improving Efficiency by Trajectory-Based Operations

NASA Technical Reports Server (NTRS)

Fernandes, Alicia Borgman; Rebollo, Juan; Koch, Michael

2016-01-01

Oceanic operations suffer from multiple inefficiencies, including pre-departure planning that does not adequately consider uncertainty in the proposed trajectory, restrictions on the routes that a flight operator can choose for an oceanic crossing, time-consuming processes and procedures for amending en route trajectories, and difficulties exchanging data between Flight Information Regions (FIRs). These inefficiencies cause aircraft to fly suboptimal trajectories, burning fuel and time that could be conserved. A concept to support integration of existing and emerging capabilities and concepts is needed to transition to an airspace system that employs Trajectory Based Operations (TBO) to improve efficiency and safety in oceanic operations. This paper describes such a concept and the results of preliminary activities to evaluate the concept, including a stakeholder feedback activity, user needs analysis, and high level benefits analysis.

Trajectories of Identity Formation Modes and Their Personality Context in Adolescence.

PubMed

Topolewska-Siedzik, Ewa; Cieciuch, Jan

2018-04-01

Identity formation is a dynamic process during adolescence. Trajectories of identity formation were assessed longitudinally in early and middle adolescents, taking into account the personality underpinnings of this process. Identity formation was conceptualized according to the circumplex of identity formation modes. The model distinguishes basic modes rooted in Marcia's categories of exploration and commitment. Plasticity and stability, the two higher order Big Five meta-traits, were used to assess personality underpinnings. This study includes five measurement waves over 1.5 years and involves 1,839 Polish participants; 914 early adolescents (53.9% girls) and 925 middle adolescents (63.8% girls). The results suggest that (1) the four identity formation modes change dynamically, showing linear and curvilinear growth and that (2) identity formation mode trajectories are more dynamic in middle adolescence than in early adolescence. The results also showed that, in the conditional model, (3) the higher-order personality factors and gender affect the growth factors of identity formation modes. Overall, trajectories of identity formation modes are more linear during early adolescence and more curvilinear during middle adolescence. The initial levels in identity trajectories are influenced by the personality metatraits but only plasticity is related to change among early adolescents.

Mineral dust: observations of emission events and modeling of transport to the upper troposphere

NASA Astrophysics Data System (ADS)

Peter, T.; Wiacek, A.; Taddeo, M.

2009-04-01

The present study explores differences between mineral dust emission events in West African and Asian (Taklimakan) deserts, focusing on the availability of bare mineral dust ice nuclei for interactions with cirrus clouds without previous processing or washout by liquid water clouds. One-week trajectory calculations with high-resolution ECMWF fields are used to track transported (Lagrangian) relative humidities with respect to liquid water and ice, allowing to estimate the formation of liquid, mixed-phase and ice clouds. Transport trajectories can reasonably be assumed to carry dust with them throughout the year, except for the months of December-February, which are quiescent with respect to dust emission in both regions. Practically none of the simulated air parcels reach regions where homogeneous nucleation can take place (T < -35°C) along trajectories that have not experienced water saturation first, i.e. it is very unlikely that mineral dust particles could be a serious competitor for homogeneous nucleation during the formation of high, cold cirrus clouds. For the temperature region between -35°C < T < 0°C, i.e. in air parcels exhibiting necessary conditions for warmer ice clouds at lower altitudes, a small but significant number of air parcels are found to follow trajectories where RHw < 100% and RHi > 100% are simultaneously maintained. However, the potential for such low ice clouds originating from the Taklimakan desert is greater than that of the Sahara by a factor of 4-6. The implication is that although the Sahara is by far the biggest source of dust in the world, the much smaller Taklimakan desert in China's Tarim Basin may be of greater importance as a source of ice nuclei affecting cirrus cloud formation. This is likely the result of several meteorological factors, including the complex regional topography combined with the higher altitude of Taklimakan dust emissions and, on the synoptic scale, the higher altitude of potential temperature levels in the free troposphere at mid-latitudes than in the tropics. Finally, the very active Bodélé source region in Africa and the Gobi Desert in Asia will also be addressed.

Quantifying kinematics of purposeful movements to real, imagined, or absent functional objects: implications for modelling trajectories for robot-assisted ADL tasks.

PubMed

Wisneski, Kimberly J; Johnson, Michelle J

2007-03-23

Robotic therapy is at the forefront of stroke rehabilitation. The Activities of Daily Living Exercise Robot (ADLER) was developed to improve carryover of gains after training by combining the benefits of Activities of Daily Living (ADL) training (motivation and functional task practice with real objects), with the benefits of robot mediated therapy (repeatability and reliability). In combining these two therapy techniques, we seek to develop a new model for trajectory generation that will support functional movements to real objects during robot training. We studied natural movements to real objects and report on how initial reaching movements are affected by real objects and how these movements deviate from the straight line paths predicted by the minimum jerk model, typically used to generate trajectories in robot training environments. We highlight key issues that to be considered in modelling natural trajectories. Movement data was collected as eight normal subjects completed ADLs such as drinking and eating. Three conditions were considered: object absent, imagined, and present. This data was compared to predicted trajectories generated from implementing the minimum jerk model. The deviations in both the plane of the table (XY) and the sagittal plane of torso (XZ) were examined for both reaches to a cup and to a spoon. Velocity profiles and curvature were also quantified for all trajectories. We hypothesized that movements performed with functional task constraints and objects would deviate from the minimum jerk trajectory model more than those performed under imaginary or object absent conditions. Trajectory deviations from the predicted minimum jerk model for these reaches were shown to depend on three variables: object presence, object orientation, and plane of movement. When subjects completed the cup reach their movements were more curved than for the spoon reach. The object present condition for the cup reach showed more curvature than in the object imagined and absent conditions. Curvature in the XZ plane of movement was greater than curvature in the XY plane for all movements. The implemented minimum jerk trajectory model was not adequate for generating functional trajectories for these ADLs. The deviations caused by object affordance and functional task constraints must be accounted for in order to allow subjects to perform functional task training in robotic therapy environments. The major differences that we have highlighted include trajectory dependence on: object presence, object orientation, and the plane of movement. With the ability to practice ADLs on the ADLER environment we hope to provide patients with a therapy paradigm that will produce optimal results and recovery.

Remaining Useful Life Prediction for Lithium-Ion Batteries Based on Gaussian Processes Mixture

PubMed Central

Li, Lingling; Wang, Pengchong; Chao, Kuei-Hsiang; Zhou, Yatong; Xie, Yang

2016-01-01

The remaining useful life (RUL) prediction of Lithium-ion batteries is closely related to the capacity degeneration trajectories. Due to the self-charging and the capacity regeneration, the trajectories have the property of multimodality. Traditional prediction models such as the support vector machines (SVM) or the Gaussian Process regression (GPR) cannot accurately characterize this multimodality. This paper proposes a novel RUL prediction method based on the Gaussian Process Mixture (GPM). It can process multimodality by fitting different segments of trajectories with different GPR models separately, such that the tiny differences among these segments can be revealed. The method is demonstrated to be effective for prediction by the excellent predictive result of the experiments on the two commercial and chargeable Type 1850 Lithium-ion batteries, provided by NASA. The performance comparison among the models illustrates that the GPM is more accurate than the SVM and the GPR. In addition, GPM can yield the predictive confidence interval, which makes the prediction more reliable than that of traditional models. PMID:27632176

Towards a Formal Semantics of Flight Plans and Trajectories

NASA Technical Reports Server (NTRS)

Hagen, George E.; Butler, Ricky W.

2014-01-01

In the National Airspace System, ight plans are often used only as a planning tool by air trac controllers and aircraft operators. These plans are implicitly translated into trajectories by the pilot or by the ight management system, and subsequently own by the aircraft. This translation process inevitably introduces di erences between the plan and the trajectory. However, given the current intended usage, exact correspondence between the plan and the trajectory is not needed. To achieve greater capacity and eciency, future air trac management concepts are being designed around the use of trajectories where predictability is extremely important. In this paper, a mathematical relationship between ight plans and trajectories is explored with the goal of making feasible, highly accurate predictions of future positions and velocities of aircraft. The goal here is to describe, in mathematically precise detail, a formal language of trajectories, whereby all receivers of the trajectory information will be able to arrive at precisely the same trajectory predication and to do this without having aircraft broadcast a large amount of data. Although even a four-dimensional ight plan is simple in structure, this paper will show that it is inherently ambiguous and will explore these issues in detail. In e ect, we propose that a rigorous semantics for ight plans can be developed and this will serve as an important stepping stone towards trajectory-based operations in the National Airspace System.

Precomputing Process Noise Covariance for Onboard Sequential Filters

NASA Technical Reports Server (NTRS)

Olson, Corwin G.; Russell, Ryan P.; Carpenter, J. Russell

2017-01-01

Process noise is often used in estimation filters to account for unmodeled and mismodeled accelerations in the dynamics. The process noise covariance acts to inflate the state covariance over propagation intervals, increasing the uncertainty in the state. In scenarios where the acceleration errors change significantly over time, the standard process noise covariance approach can fail to provide effective representation of the state and its uncertainty. Consider covariance analysis techniques provide a method to precompute a process noise covariance profile along a reference trajectory using known model parameter uncertainties. The process noise covariance profile allows significantly improved state estimation and uncertainty representation over the traditional formulation. As a result, estimation performance on par with the consider filter is achieved for trajectories near the reference trajectory without the additional computational cost of the consider filter. The new formulation also has the potential to significantly reduce the trial-and-error tuning currently required of navigation analysts. A linear estimation problem as described in several previous consider covariance analysis studies is used to demonstrate the effectiveness of the precomputed process noise covariance, as well as a nonlinear descent scenario at the asteroid Bennu with optical navigation.

Precomputing Process Noise Covariance for Onboard Sequential Filters

NASA Technical Reports Server (NTRS)

Olson, Corwin G.; Russell, Ryan P.; Carpenter, J. Russell

2017-01-01

Process noise is often used in estimation filters to account for unmodeled and mismodeled accelerations in the dynamics. The process noise covariance acts to inflate the state covariance over propagation intervals, increasing the uncertainty in the state. In scenarios where the acceleration errors change significantly over time, the standard process noise covariance approach can fail to provide effective representation of the state and its uncertainty. Consider covariance analysis techniques provide a method to precompute a process noise covariance profile along a reference trajectory, using known model parameter uncertainties. The process noise covariance profile allows significantly improved state estimation and uncertainty representation over the traditional formulation. As a result, estimation performance on par with the consider filter is achieved for trajectories near the reference trajectory without the additional computational cost of the consider filter. The new formulation also has the potential to significantly reduce the trial-and-error tuning currently required of navigation analysts. A linear estimation problem as described in several previous consider covariance analysis publications is used to demonstrate the effectiveness of the precomputed process noise covariance, as well as a nonlinear descent scenario at the asteroid Bennu with optical navigation.

Introducing the fit-criteria assessment plot - A visualisation tool to assist class enumeration in group-based trajectory modelling.

PubMed

Klijn, Sven L; Weijenberg, Matty P; Lemmens, Paul; van den Brandt, Piet A; Lima Passos, Valéria

2017-10-01

Background and objective Group-based trajectory modelling is a model-based clustering technique applied for the identification of latent patterns of temporal changes. Despite its manifold applications in clinical and health sciences, potential problems of the model selection procedure are often overlooked. The choice of the number of latent trajectories (class-enumeration), for instance, is to a large degree based on statistical criteria that are not fail-safe. Moreover, the process as a whole is not transparent. To facilitate class enumeration, we introduce a graphical summary display of several fit and model adequacy criteria, the fit-criteria assessment plot. Methods An R-code that accepts universal data input is presented. The programme condenses relevant group-based trajectory modelling output information of model fit indices in automated graphical displays. Examples based on real and simulated data are provided to illustrate, assess and validate fit-criteria assessment plot's utility. Results Fit-criteria assessment plot provides an overview of fit criteria on a single page, placing users in an informed position to make a decision. Fit-criteria assessment plot does not automatically select the most appropriate model but eases the model assessment procedure. Conclusions Fit-criteria assessment plot is an exploratory, visualisation tool that can be employed to assist decisions in the initial and decisive phase of group-based trajectory modelling analysis. Considering group-based trajectory modelling's widespread resonance in medical and epidemiological sciences, a more comprehensive, easily interpretable and transparent display of the iterative process of class enumeration may foster group-based trajectory modelling's adequate use.

The Cancer Family Caregiving Experience: An Updated and Expanded Conceptual Model

PubMed Central

Fletcher, Barbara Swore; Miaskowski, Christine; Given, Barbara; Schumacher, Karen

2011-01-01

Objective The decade from 2000–2010 was an era of tremendous growth in family caregiving research specific to the cancer population. This research has implications for how cancer family caregiving is conceptualized, yet the most recent comprehensive model of cancer family caregiving was published ten years ago. Our objective was to develop an updated and expanded comprehensive model of the cancer family caregiving experience, derived from concepts and variables used in research during past ten years. Methods A conceptual model was developed based on cancer family caregiving research published from 2000–2010. Results Our updated and expanded model has three main elements: 1) the stress process, 2) contextual factors, and 3) the cancer trajectory. Emerging ways of conceptualizing the relationships between and within model elements are addressed, as well as an emerging focus on caregiver-patient dyads as the unit of analysis. Conclusions Cancer family caregiving research has grown dramatically since 2000 resulting in a greatly expanded conceptual landscape. This updated and expanded model of the cancer family caregiving experience synthesizes the conceptual implications of an international body of work and demonstrates tremendous progress in how cancer family caregiving research is conceptualized. PMID:22000812

Multi-Objective Hybrid Optimal Control for Multiple-Flyby Low-Thrust Mission Design

NASA Technical Reports Server (NTRS)

Englander, Jacob A.; Vavrina, Matthew A.; Ghosh, Alexander R.

2015-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated. The customer who commissions a trajectory design is not usually interested in a point solution, but rather the exploration of the trade space of trajectories between several different objective functions. This can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a multi-objective hybrid optimal control problem. The method is demonstrated on a hypothetical mission to the main asteroid belt.

Trajectories of posttraumatic stress symptoms (PTSS) after major war among Palestinian children: Trauma, family- and child-related predictors.

PubMed

Punamäki, Raija-Leena; Palosaari, Esa; Diab, Marwan; Peltonen, Kirsi; Qouta, Samir R

2015-02-01

Research shows great individual variation in changes in posttraumatic stress symptoms (PTSSs) after major traumas of terrorist attacks, military combat, and natural disasters. Earlier studies have identified specific mental health trajectories both in children and adults. This study aimed, first, to identify potential PTSS-related trajectories by using latent class growth analyses among children in a three-wave assessment after the 2008/2009 War on Gaza, Palestine. Second, it analyzed how family- and child related factors (e.g., attachment relations, posttraumatic cognitions (PTCs), guilt, and emotion regulation) associate with the trajectory class membership. The sample consisted of 240 Palestinian children (49.4% girls and 50.6% boys) of 10-13 years of age (M=11.29, SD=0.68), who completed PTSS (CRIES) assessments at 3 (T1), 5 (T2), and 11 (T3) months after the war. Children reported their personal exposure to war trauma, attachment style, cognitive trauma processing, and emotion regulation, and their parents reported family war trauma exposure and attachment style. Results revealed a three-trajectory solution, a majority of children belonging to the Recovery trajectory (n=183), and a minority belonged either to Resistant trajectory (n=29) or to Increasing symptoms trajectory (n=28). Low levels of negative posttraumatic cognitive appraisals, feelings of guilt and emotion regulation were characteristic of children in the Resistant trajectory as compared to Increasing symptoms trajectory. Father׳s attachment security was further associated with the Resistant trajectory membership. Children׳s attachment avoidance and high parental trauma were typical to children in Recovery trajectory (as compared to the Increasing symptoms trajectory). Copyright © 2014 Elsevier B.V. All rights reserved.

The Atmospheric Data Acquisition And Interpolation Process For Center-TRACON Automation System

NASA Technical Reports Server (NTRS)

Jardin, M. R.; Erzberger, H.; Denery, Dallas G. (Technical Monitor)

1995-01-01

The Center-TRACON Automation System (CTAS), an advanced new air traffic automation program, requires knowledge of spatial and temporal atmospheric conditions such as the wind speed and direction, the temperature and the pressure in order to accurately predict aircraft trajectories. Real-time atmospheric data is available in a grid format so that CTAS must interpolate between the grid points to estimate the atmospheric parameter values. The atmospheric data grid is generally not in the same coordinate system as that used by CTAS so that coordinate conversions are required. Both the interpolation and coordinate conversion processes can introduce errors into the atmospheric data and reduce interpolation accuracy. More accurate algorithms may be computationally expensive or may require a prohibitively large amount of data storage capacity so that trade-offs must be made between accuracy and the available computational and data storage resources. The atmospheric data acquisition and processing employed by CTAS will be outlined in this report. The effects of atmospheric data processing on CTAS trajectory prediction will also be analyzed, and several examples of the trajectory prediction process will be given.

Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 1: Analytic and user's manual

NASA Technical Reports Server (NTRS)

Byrnes, D. V.; Carney, P. C.; Underwood, J. W.; Vogt, E. D.

1974-01-01

Development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system is reported. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs (STEAP). The program NOMNAL targets a transfer trajectory from Earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty. Execution errors at injection, midcourse correction and orbit insertion maneuvers are analyzed along with the navigation uncertainty to determine trajectory control uncertainties and fuel-sizing requirements. The program is also capable of generalized covariance analyses.

A unified motion planning approach for redundant and non-redundant manipulators with actuator constraints. Ph.D. Thesis Final Report

NASA Technical Reports Server (NTRS)

Chung, Ching-Luan

1990-01-01

The term trajectory planning has been used to refer to the process of determining the time history of joint trajectory of each joint variable corresponding to a specified trajectory of the end effector. The trajectory planning problem was solved as a purely kinematic problem. The drawback is that there is no guarantee that the actuators can deliver the effort necessary to track the planned trajectory. To overcome this limitation, a motion planning approach which addresses the kinematics, dynamics, and feedback control of a manipulator in a unified framework was developed. Actuator constraints are taken into account explicitly and a priori in the synthesis of the feedback control law. Therefore the result of applying the motion planning approach described is not only the determination of the entire set of joint trajectories but also a complete specification of the feedback control strategy which would yield these joint trajectories without violating actuator constraints. The effectiveness of the unified motion planning approach is demonstrated on two problems which are of practical interest in manipulator robotics.

Mutual information in the evolution of trajectories in discrete aiming movements.

PubMed

Lai, Shih-Chiung; Mayer-Kress, Gottfried; Newell, Karl M

2008-07-01

This study investigated the mutual information in the trajectories of discrete aiming movements on a computer controlled graphics tablet where movement time ( 300 - 2050 ms) was manipulated in a given distance (100 mm) and movement distance (15-240 mm) in 2 given movement times (300 ms and 800 ms ). For the distance-fixed conditions, there was higher mutual information in the slower movements in the 0 vs. 80-100% trajectory point comparisons, whereas the mutual information was higher for the faster movements when comparing within the 80 and 100% points of the movement trajectory. For the time-fixed conditions, the spatial constraints led to a decreasing pattern of the mutual information throughout the points of the trajectory, with the highest mutual information found in the 80 vs. 100% comparison. Overall, the pattern of mutual information reveals systematic modulation of the trajectories between the attractive fixed point of the target as a function of movement condition. These mutual information patterns are postulated to be the consequence of the different relative contributions of feedforward and feedback control processes in trajectory formation as a function of task constraints.

Representation of virtual arm movements in precuneus.

PubMed

Dohle, Christian; Stephan, Klaus Martin; Valvoda, Jakob T; Hosseiny, Omid; Tellmann, Lutz; Kuhlen, Torsten; Seitz, Rüdiger J; Freund, Hans-Joachim

2011-02-01

Arm movements can easily be adapted to different biomechanical constraints. However, the cortical representation of the processing of visual input and its transformation into motor commands remains poorly understood. In a visuo-motor dissociation paradigm, subjects were presented with a 3-D computer-graphical representation of a human arm, presenting movements of the subjects' right arm either as right or left arm. In order to isolate possible effects of coordinate transformations, coordinate mirroring at the body midline was implemented independently. In each of the resulting four conditions, 10 normal, right-handed subjects performed three runs of circular movements, while being scanned with O(15)-Butanol-PET. Kinematic analysis included orientation and accuracy of a fitted ellipsoid trajectory. Imaging analysis was performed with SPM 99 with activations threshold at P < 0.0001 (not corrected). The shape of the trajectory was dependent on the laterality of the arm, irrespective of movement mirroring, and accompanied by a robust activation difference in the contralateral precuneus. Movement mirroring decreased movement accuracy, which was related to increased activation in the left insula. Those two movement conditions that cannot be observed in reality were related to an activation focus at the left middle temporal gyrus, but showed no influence on movement kinematics. These findings demonstrate the prominent role of the precuneus for mediating visuo-motor transformations and have implications for the use of mirror therapy and virtual reality techniques, especially avatars, such as Nintendo Wii in neurorehabilitation.

Dual Trajectories of Reactive and Proactive Aggression from Mid-childhood to Early Adolescence: Relations to Sensation Seeking, Risk Taking, and Moral Reasoning.

PubMed

Cui, Lixian; Colasante, Tyler; Malti, Tina; Ribeaud, Denis; Eisner, Manuel P

2016-05-01

We examined the roles of sensation seeking, risk taking, and moral reasoning in the development of reactive and proactive aggression. Data were drawn from a multiethnic, longitudinal study of children from Switzerland (N = 1571; 52 % male; assessed annually over 6 years; 7-years-old at Time 1). At all 6 time points, teachers reported children's reactive and proactive aggression via questionnaire. Children's sensation seeking (at Time 1) and risk taking (at Time 2) were assessed with two interactive computer tasks and their moral reasoning was assessed at Time 2 in response to four hypothetical vignettes depicting moral transgressions. Parallel process Latent Class Growth Analysis (PP-LCGA) identified six dual trajectories of reactive and proactive aggression. Children with either childhood-limited or adolescent-onset aggression showed high sensation seeking. Children with persistent, high levels of both reactive and proactive aggression across time showed high levels of sensation seeking and risk taking, as well as low levels of moral reasoning. Children with only high risk taking were more likely to display moderate levels of aggression across time. These findings highlight the shared and differential roles of sensation seeking, risk taking, and moral reasoning in the dual development of reactive and proactive aggression from mid-childhood to early adolescence. We discuss implications for common and tailored strategies to combat these aggression subtypes.

Family Violence Pathways and Externalizing Behavior in Youth.

PubMed

Bozzay, Melanie L; Joy, Lendi N; Verona, Edelyn

2017-08-01

While studies suggest that youth who experience violence in the home are more likely to engage in externalizing behaviors (e.g., aggression, substance use, rule breaking), research is needed to understand factors that may explain how family violence is linked to externalizing, and whether there may be gender-specific trajectories to this outcome. The present study used a cross-sectional design and multigroup, path analytic modeling to test the degree to which personality traits (negative emotionality, constraint) in boys and girls (Model 1), as well as status offending primarily in girls (Model 2), may help explain relationships between exposure to familial adversity (witnessing family violence and child abuse) and adolescent externalizing behaviors in a mixed-gender, community sample with both caregiver and youth reports ( N = 237, 57% female, 10-17 years old). Results indicated that personality traits fully explained the relationship between witnessing family violence and externalizing and partially explained the relationship between child abuse and externalizing among youth. Despite theory suggesting a female-specific trajectory involving status offenses, both models were similarly relevant for boys and girls. These findings have implications for understanding processes by which adverse family circumstances may relate to externalizing behavior in youth. Preliminary suggestions are provided for future longitudinal research, policy changes, and clinical techniques that may be essential in preventing the progression to long-term adverse outcomes among youth.

Brownian relaxation of an inelastic sphere in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bird, G. A., E-mail: gab@gab.com.au

2016-06-15

The procedures that are used to calculate the forces and moments on an aerodynamic body in the rarefied gas of the upper atmosphere are applied to a small sphere of the size of an aerosol particle at sea level. While the gas-surface interaction model that provides accurate results for macroscopic bodies may not be appropriate for bodies that are comprised of only about a thousand atoms, it provides a limiting case that is more realistic than the elastic model. The paper concentrates on the transfer of energy from the air to an initially stationary sphere as it acquires Brownian motion.more » Individual particle trajectories vary wildly, but a clear relaxation process emerges from an ensemble average over tens of thousands of trajectories. The translational and rotational energies in equilibrium Brownian motion are determined. Empirical relationships are obtained for the mean translational and rotational relaxation times, the mean initial power input to the particle, the mean rates of energy transfer between the particle and air, and the diffusivity. These relationships are functions of the ratio of the particle mass to an average air molecule mass and the Knudsen number, which is the ratio of the mean free path in the air to the particle diameter. The ratio of the molecular radius to the particle radius also enters as a correction factor. The implications of Brownian relaxation for the second law of thermodynamics are discussed.« less

Dynamic evolution and biogenesis of small RNAs during sex reversal.

PubMed

Liu, Jie; Luo, Majing; Sheng, Yue; Hong, Qiang; Cheng, Hanhua; Zhou, Rongjia

2015-05-06

Understanding origin, evolution and functions of small RNA (sRNA) genes has been a great challenge in the past decade. Molecular mechanisms underlying sexual reversal in vertebrates, particularly sRNAs involved in this process, are largely unknown. By deep-sequencing of small RNA transcriptomes in combination with genomic analysis, we identified a large amount of piRNAs and miRNAs including over 1,000 novel miRNAs, which were differentially expressed during gonad reversal from ovary to testis via ovotesis. Biogenesis and expressions of miRNAs were dynamically changed during the reversal. Notably, phylogenetic analysis revealed dynamic expansions of miRNAs in vertebrates and an evolutionary trajectory of conserved miR-17-92 cluster in the Eukarya. We showed that the miR-17-92 cluster in vertebrates was generated through multiple duplications from ancestor miR-92 in invertebrates Tetranychus urticae and Daphnia pulex from the Chelicerata around 580 Mya. Moreover, we identified the sexual regulator Dmrt1 as a direct target of the members miR-19a and -19b in the cluster. These data suggested dynamic biogenesis and expressions of small RNAs during sex reversal and revealed multiple expansions and evolutionary trajectory of miRNAs from invertebrates to vertebrates, which implicate small RNAs in sexual reversal and provide new insight into evolutionary and molecular mechanisms underlying sexual reversal.

Characterizing the Asian Tropopause Aerosol Layer (ATAL) Using Satellite Observations, Balloon Measurements and a Chemical Transport Model

NASA Technical Reports Server (NTRS)

Fairlie, T. D.; Vernier, J.-P.; Liu, H.; Deshler, T.; Natarajan, M.; Bedka, K.; Wegner, T.; Baker, N.; Gadhavi, H.; Ratnam, M. V.;

The Asian Tropopause Aerosol Layer: Balloon-Borne Measurements, Satellite Observations and Modeling Approaches

NASA Technical Reports Server (NTRS)

Fairlie, T. D.; Vernier, J.-P.; Natarajan, M.; Deshler, Terry; Liu, H.; Wegner, T.; Baker, N.; Gadhavi, H.; Jayaraman, A.; Pandit, A.;

Effects of Telecoupling on Global Vegetation Dynamics

NASA Astrophysics Data System (ADS)

Viña, A.; Liu, J.

2016-12-01

With the ever increasing trend in telecoupling processes, such as international trade, all countries around the world are becoming more interdependent. However, the effects of this growing interdependence on vegetation (e.g., shifts in the geographic extent and distribution) remain unknown even though vegetation dynamics are crucially important for food production, carbon sequestration, provision of other ecosystem services, and biodiversity conservation. In this study we evaluate the effects of international trade on the spatio-temporal trajectories of vegetation at national and global scales, using vegetation index imagery collected over more than three decades by the Advanced Very High Resolution Radiometer (AVHRR) satellite sensor series together with concurrent national and international data on international trade (and its associated movement of people, goods, services and information). The spatio-temporal trajectories of vegetation are obtained using the scale of fluctuation technique, which is based on the decomposition of the AVHRR image time series to obtain information on its spatial dependence structure over time. Similar to the correlation length, the scale of fluctuation corresponds to the range over which fluctuations in the vegetation index are spatially correlated. Results indicate that global vegetation has changed drastically over the last three decades. These changes are not uniform across space, with hotspots in active trading countries. This study not only has direct implications for understanding global vegetation dynamics, but also sheds important insights on the complexity of human-nature interactions across telecoupled systems.

A Robotics-Based Approach to Modeling of Choice Reaching Experiments on Visual Attention

PubMed Central

Strauss, Soeren; Heinke, Dietmar

2012-01-01

The paper presents a robotics-based model for choice reaching experiments on visual attention. In these experiments participants were asked to make rapid reach movements toward a target in an odd-color search task, i.e., reaching for a green square among red squares and vice versa (e.g., Song and Nakayama, 2008). Interestingly these studies found that in a high number of trials movements were initially directed toward a distractor and only later were adjusted toward the target. These “curved” trajectories occurred particularly frequently when the target in the directly preceding trial had a different color (priming effect). Our model is embedded in a closed-loop control of a LEGO robot arm aiming to mimic these reach movements. The model is based on our earlier work which suggests that target selection in visual search is implemented through parallel interactions between competitive and cooperative processes in the brain (Heinke and Humphreys, 2003; Heinke and Backhaus, 2011). To link this model with the control of the robot arm we implemented a topological representation of movement parameters following the dynamic field theory (Erlhagen and Schoener, 2002). The robot arm is able to mimic the results of the odd-color search task including the priming effect and also generates human-like trajectories with a bell-shaped velocity profile. Theoretical implications and predictions are discussed in the paper. PMID:22529827

Developmental aspects of a life course approach to healthy ageing

PubMed Central

Cooper, C.; Aihie Sayer, A.; Eendebak, R. J.; Clough, G. F.; Beard, J. R.

2016-01-01

Abstract We examine the mechanistic basis and wider implications of adopting a developmental perspective on human ageing. Previous models of ageing have concentrated on its genetic basis, or the detrimental effects of accumulated damage, but also have raised issues about whether ageing can be viewed as adaptive itself, or is a consequence of other adaptive processes, for example if maintenance and repair processes in the period up to reproduction are traded off against later decline in function. A life course model places ageing in the context of the attainment of peak capacity for a body system, starting in early development when plasticity permits changes in structure and function induced by a range of environmental stimuli, followed by a period of decline, the rate of which depends on the peak attained as well as the later life conditions. Such path dependency in the rate of ageing may offer new insights into its modification. Focusing on musculoskeletal and cardiovascular function, we discuss this model and the possible underlying mechanisms, including endothelial function, oxidative stress, stem cells and nutritional factors such as vitamin D status. Epigenetic changes induced during developmental plasticity, and immune function may provide a common mechanistic process underlying a life course model of ageing. The life course trajectory differs in high and low resource settings. New insights into the developmental components of the life course model of ageing may lead to the design of biomarkers of later chronic disease risk and to new interventions to promote healthy ageing, with important implications for public health. PMID:26518329

Developmental aspects of a life course approach to healthy ageing.

PubMed

Hanson, M A; Cooper, C; Aihie Sayer, A; Eendebak, R J; Clough, G F; Beard, J R

2016-04-15

We examine the mechanistic basis and wider implications of adopting a developmental perspective on human ageing. Previous models of ageing have concentrated on its genetic basis, or the detrimental effects of accumulated damage, but also have raised issues about whether ageing can be viewed as adaptive itself, or is a consequence of other adaptive processes, for example if maintenance and repair processes in the period up to reproduction are traded off against later decline in function. A life course model places ageing in the context of the attainment of peak capacity for a body system, starting in early development when plasticity permits changes in structure and function induced by a range of environmental stimuli, followed by a period of decline, the rate of which depends on the peak attained as well as the later life conditions. Such path dependency in the rate of ageing may offer new insights into its modification. Focusing on musculoskeletal and cardiovascular function, we discuss this model and the possible underlying mechanisms, including endothelial function, oxidative stress, stem cells and nutritional factors such as vitamin D status. Epigenetic changes induced during developmental plasticity, and immune function may provide a common mechanistic process underlying a life course model of ageing. The life course trajectory differs in high and low resource settings. New insights into the developmental components of the life course model of ageing may lead to the design of biomarkers of later chronic disease risk and to new interventions to promote healthy ageing, with important implications for public health. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Transitions in Arctic ecosystems: Ecological implications of a changing hydrological regime

NASA Astrophysics Data System (ADS)

Wrona, Frederick J.; Johansson, Margareta; Culp, Joseph M.; Jenkins, Alan; Mârd, Johanna; Myers-Smith, Isla H.; Prowse, Terry D.; Vincent, Warwick F.; Wookey, Philip A.

2016-03-01

Numerous international scientific assessments and related articles have, during the last decade, described the observed and potential impacts of climate change as well as other related environmental stressors on Arctic ecosystems. There is increasing recognition that observed and projected changes in freshwater sources, fluxes, and storage will have profound implications for the physical, biogeochemical, biological, and ecological processes and properties of Arctic terrestrial and freshwater ecosystems. However, a significant level of uncertainty remains in relation to forecasting the impacts of an intensified hydrological regime and related cryospheric change on ecosystem structure and function. As the terrestrial and freshwater ecology component of the Arctic Freshwater Synthesis, we review these uncertainties and recommend enhanced coordinated circumpolar research and monitoring efforts to improve quantification and prediction of how an altered hydrological regime influences local, regional, and circumpolar-level responses in terrestrial and freshwater systems. Specifically, we evaluate (i) changes in ecosystem productivity; (ii) alterations in ecosystem-level biogeochemical cycling and chemical transport; (iii) altered landscapes, successional trajectories, and creation of new habitats; (iv) altered seasonality and phenological mismatches; and (v) gains or losses of species and associated trophic interactions. We emphasize the need for developing a process-based understanding of interecosystem interactions, along with improved predictive models. We recommend enhanced use of the catchment scale as an integrated unit of study, thereby more explicitly considering the physical, chemical, and ecological processes and fluxes across a full freshwater continuum in a geographic region and spatial range of hydroecological units (e.g., stream-pond-lake-river-near shore marine environments).

Robust flight design for an advanced launch system vehicle

NASA Astrophysics Data System (ADS)

Dhand, Sanjeev K.; Wong, Kelvin K.

Current launch vehicle trajectory design philosophies are generally based on maximizing payload capability. This approach results in an expensive trajectory design process for each mission. Two concepts of robust flight design have been developed to significantly reduce this cost: Standardized Trajectories and Command Multiplier Steering (CMS). These concepts were analyzed for an Advanced Launch System (ALS) vehicle, although their applicability is not restricted to any particular vehicle. Preliminary analysis has demonstrated the feasibility of these concepts at minimal loss in payload capability.

Trajectories of School Engagement during Adolescence: Implications for Grades, Depression, Delinquency, and Substance Use

ERIC Educational Resources Information Center

Li, Yibing; Lerner, Richard M.

2011-01-01

Using longitudinal data from the 4-H Study of Positive Youth Development, the authors assessed 1,977 adolescents across Grades 5 to 8 to determine if there were distinctive developmental paths for behavioral and emotional school engagement; if these paths varied in relation to sex, race/ethnicity, and family socioeconomic status (SES); and whether…

Longitudinal Examination of Aggression and Study Skills from Middle to High School: Implications for Dropout Prevention

ERIC Educational Resources Information Center

Orpinas, Pamela; Raczynski, Katherine; Hsieh, Hsien-Lin; Nahapetyan, Lusine; Horne, Arthur M.

2018-01-01

Background: High school completion provides health and economic benefits. The purpose of this study is to describe dropout rates based on longitudinal trajectories of aggression and study skills using teacher ratings. Methods: The sample consisted of 620 randomly selected sixth graders. Every year from Grade 6 to 12, a teacher completed a…

The Latino Male Educational Trajectory: A Precollege Econometric Model and 21st Century Implications

ERIC Educational Resources Information Center

Ortiz, Ramon, Jr.

2017-01-01

The twin challenges of aging demographics in the United States and the need for higher levels of education to compete in the new technology-based economy is creating a socioeconomic paradox (Friedman, 2005). As the Baby Boomer generation retires, those replacing them are increasingly a non-White population. This demographic shift is inevitable and…

A Comparative Perspective of Black College Males on the Achievement Gap: Implications for School Counselors

ERIC Educational Resources Information Center

Bethell, Detra

2013-01-01

The dominant discourse regarding Black males in America is that they are less academically successful than European American males and Black females. Similarly, Black males in the Bahamas are described as less successful than Black Bahamian females. School Counselors are in a unique position to alter the trajectory of success for Black males if…

The Unequal Burden of Weight Gain: An Intersectional Approach to Understanding Social Disparities in BMI Trajectories from 1986 to 2001/2002

ERIC Educational Resources Information Center

Ailshire, Jennifer A.; House, James S.

2011-01-01

The implications of recent weight gain trends for widening social disparities in body weight in the United States are unclear. Using an intersectional approach to studying inequality, and the longitudinal and nationally representative American's Changing Lives study (1986-2001/2002), we examine social disparities in body mass index trajectories…

Hospitals, finance, and health system reform in Britain and the United States, c. 1910-1950: historical revisionism and cross-national comparison.

PubMed

Gorsky, Martin

2012-06-01

Comparative histories of health system development have been variously influenced by the theoretical approaches of historical institutionalism, political pluralism, and labor mobilization. Britain and the United States have figured significantly in this literature because of their very different trajectories. This article explores the implications of recent research on hospital history in the two countries for existing historiographies, particularly the coming of the National Health Service in Britain. It argues that the two hospital systems initially developed in broadly similar ways, despite the very different outcomes in the 1940s. Thus, applying the conceptual tools used to explain the U.S. trajectory can deepen appreciation of events in Britain. Attention focuses particularly on working-class hospital contributory schemes and their implications for finance, governance, and participation; these are then compared with Blue Cross and U.S. hospital prepayment. While acknowledging the importance of path dependence in shaping attitudes of British bureaucrats toward these schemes, analysis emphasizes their failure in pressure group politics, in contrast to the United States. In both countries labor was also crucial, in the United States sustaining employment-based prepayment and in Britain broadly supporting system reform.

Perception of object trajectory: parsing retinal motion into self and object movement components.

PubMed

Warren, Paul A; Rushton, Simon K

2007-08-16

A moving observer needs to be able to estimate the trajectory of other objects moving in the scene. Without the ability to do so, it would be difficult to avoid obstacles or catch a ball. We hypothesized that neural mechanisms sensitive to the patterns of motion generated on the retina during self-movement (optic flow) play a key role in this process, "parsing" motion due to self-movement from that due to object movement. We investigated this "flow parsing" hypothesis by measuring the perceived trajectory of a moving probe placed within a flow field that was consistent with movement of the observer. In the first experiment, the flow field was consistent with an eye rotation; in the second experiment, it was consistent with a lateral translation of the eyes. We manipulated the distance of the probe in both experiments and assessed the consequences. As predicted by the flow parsing hypothesis, manipulating the distance of the probe had differing effects on the perceived trajectory of the probe in the two experiments. The results were consistent with the scene geometry and the type of simulated self-movement. In a third experiment, we explored the contribution of local and global motion processing to the results of the first two experiments. The data suggest that the parsing process involves global motion processing, not just local motion contrast. The findings of this study support a role for optic flow processing in the perception of object movement during self-movement.

Going beyond Clustering in MD Trajectory Analysis: An Application to Villin Headpiece Folding

PubMed Central

Rajan, Aruna; Freddolino, Peter L.; Schulten, Klaus

2010-01-01

Recent advances in computing technology have enabled microsecond long all-atom molecular dynamics (MD) simulations of biological systems. Methods that can distill the salient features of such large trajectories are now urgently needed. Conventional clustering methods used to analyze MD trajectories suffer from various setbacks, namely (i) they are not data driven, (ii) they are unstable to noise and changes in cut-off parameters such as cluster radius and cluster number, and (iii) they do not reduce the dimensionality of the trajectories, and hence are unsuitable for finding collective coordinates. We advocate the application of principal component analysis (PCA) and a non-metric multidimensional scaling (nMDS) method to reduce MD trajectories and overcome the drawbacks of clustering. To illustrate the superiority of nMDS over other methods in reducing data and reproducing salient features, we analyze three complete villin headpiece folding trajectories. Our analysis suggests that the folding process of the villin headpiece is structurally heterogeneous. PMID:20419160

Going beyond clustering in MD trajectory analysis: an application to villin headpiece folding.

PubMed

Rajan, Aruna; Freddolino, Peter L; Schulten, Klaus

2010-04-15

Recent advances in computing technology have enabled microsecond long all-atom molecular dynamics (MD) simulations of biological systems. Methods that can distill the salient features of such large trajectories are now urgently needed. Conventional clustering methods used to analyze MD trajectories suffer from various setbacks, namely (i) they are not data driven, (ii) they are unstable to noise and changes in cut-off parameters such as cluster radius and cluster number, and (iii) they do not reduce the dimensionality of the trajectories, and hence are unsuitable for finding collective coordinates. We advocate the application of principal component analysis (PCA) and a non-metric multidimensional scaling (nMDS) method to reduce MD trajectories and overcome the drawbacks of clustering. To illustrate the superiority of nMDS over other methods in reducing data and reproducing salient features, we analyze three complete villin headpiece folding trajectories. Our analysis suggests that the folding process of the villin headpiece is structurally heterogeneous.

Unravelling the dynamical origin of below- and near-threshold harmonic generation of H 2 + in an intense NIR laser field

DOE PAGES

Heslar, John; Chu, Shih-I.

2016-11-24

Recently, the study of near- and below- threshold regime harmonics as a potential source of intense coherent vacuum-ultraviolet radiation has received considerable attention. However, the dynamical origin of these lower harmonics, particularly for the molecular systems, is less understood and largely unexplored. Here we perform the first fully ab initio and high precision 3D quantum study of the below- and near-threshold harmonic generation of H 2 + molecules in an intense 800-nm near-infrared (NIR) laser field. Furthermore, combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, we explore in-depth the roles of various quantummore » trajectories, including short- and long trajectories, multiphoton trajectories, resonance-enhanced trajectories, and multiple rescattering trajectories of the below- and near- threshold harmonic generation processes. Our results shed new light on the dynamical origin of the below- and near-threshold harmonic generation and various quantum trajectories for diatomic molecules for the first time.« less

Trajectories of Math and Reading Achievement in Low Achieving Children in Elementary School: Effects of Early and Later Retention in Grade

PubMed Central

Moser, Stephanie E.; West, Stephen G.; Hughes, Jan N.

2012-01-01

This study investigated the effects of retention or promotion in first grade on growth trajectories in mathematics and reading achievement over the elementary school years (grades 1–5). From a large multiethnic sample (n = 784) of children who were below the median in literacy at school entrance, 363 children who were either promoted (n = 251) or retained (n = 112) in first grade could be successfully matched on 72 background variables. Achievement was measured annually using Woodcock-Johnson W scores; scores of retained children were shifted back one year to permit same-grade comparisons. Using longitudinal growth curve analysis, trajectories of math and reading scores for promoted and retained children were compared. Retained children received a one year boost in achievement; this boost fully dissipated by the end of elementary school. The pattern of subsequent retention in grades 2, 3 and 4 and placement in special education of the sample during the elementary school years is also described and their effects are explored. Policy implications for interventions for low achieving children are considered. PMID:23335818

Shuttle derived atmospheric density model. Part 2: STS atmospheric implications for AOTV trajectory analysis, a proposed GRAM perturbation density model

NASA Technical Reports Server (NTRS)

Findlay, J. T.; Kelly, G. M.; Troutman, P. A.

1984-01-01

A perturbation model to the Marshall Space Flight Center (MSFC) Global Reference Atmosphere Model (GRAM) was developed for use in the Aeroassist Orbital Transfer Vehicle (AOTV) trajectory and analysis. The model reflects NASA Space Shuttle experience over the first twelve entry flights. The GRAM was selected over the Air Force 1978 Reference Model because of its more general formulation and wider use throughout NASA. The add-on model, a simple scaling with altitude to reflect density structure encountered by the Shuttle Orbiter was selected principally to simplify implementation. Perturbations, by season, can be utilized to minimize the number of required simulations, however, exact Shuttle flight history can be exercised using the same model if desired. Such a perturbation model, though not meteorologically motivated, enables inclusion of High Resolution Accelerometer Package (HiRAP) results in the thermosphere. Provision is made to incorporate differing perturbations during the AOTV entry and exit phases of the aero-asist maneuver to account for trajectory displacement (geographic) along the ground track.

Effect of School Belonging Trajectories in Grades 6–8 on Achievement: Gender and Ethnic Differences

PubMed Central

Hughes, Jan N.; Im, Myung Hee; Allee, Paula J.

2015-01-01

This study investigated the association between trajectories of school belonging across grades 6–8 and academic achievement in grade 8 in an ethnically diverse sample of 527 academically at-risk adolescents. Students reported annually on school belonging. Reading and math achievement were assessed at grade 5 (baseline) and grade 8. Interactive effects of gender and ethnicity were found in the conditional growth models for school belonging. Girls of all ethnicities had identical growth trajectories and reported higher initial school belonging than Euro-American or Latino boys. Latino and Euro-American males had lower initial level of school belonging than African American males, and Latino males had lower growth in school belonging than Euro-American males. In structural equation modeling (SEM) analyses, initial level of school belonging predicted grade 8 reading for girls and grade 8 math for boys and girls, above prior achievement and school and child covariates, but growth in school belonging predicted grade 8 achievement only for African American students. Implications for strategies to improve school belonging among academically at-risk youth are discussed. PMID:26563601

The clinical trajectory of emerging bipolar disorder among the high-risk offspring of bipolar parents: current understanding and future considerations.

PubMed

Duffy, A; Vandeleur, C; Heffer, N; Preisig, M

2017-11-22

Relatively little is known about the onset of bipolar disorder, yet the early illness course is already associated with significant morbidity and mortality. Therefore, characterizing the bipolar illness trajectory is key to risk prediction and early intervention advancement. In this narrative review, we discuss key findings from prospective longitudinal studies of the high-risk offspring of bipolar parents and related meta-analyses that inform us about the clinical trajectory of emerging bipolar disorder. Challenges such as phenotypic and etiologic heterogeneity and the non-specificity of early symptoms and syndromes are highlighted. Implications of the findings for both research and clinical practice are discussed. Bipolar disorder in young people at familial risk does not typically onset with a hypomanic or manic episode. Rather the first activated episode is often preceded by years of impairing psychopathological states that vary over development and across emerging bipolar subtype. Taking heterogeneity into account and adopting a more comprehensive approach to diagnosis seems necessary to advance earlier identification and our understanding of the onset of bipolar disorder.

Sex differences in the implications of partner physical attractiveness for the trajectory of marital satisfaction.

PubMed

Meltzer, Andrea L; McNulty, James K; Jackson, Grace L; Karney, Benjamin R

2014-03-01

Do men value physical attractiveness in a mate more than women? Scientists in numerous disciplines believe that they do, but recent research using speed-dating paradigms suggests that males and females are equally influenced by physical attractiveness when choosing potential mates. Nevertheless, the premise of the current work is that sex differences in the importance of physical attractiveness are most likely to emerge in research on long-term relationships. Accordingly, the current work drew from 4 independent, longitudinal studies to examine sex differences in the implications of partner physical attractiveness for trajectories of marital satisfaction. In all 4 studies, both partners' physical attractiveness was objectively rated at baseline, and both partners reported their marital satisfaction up to 8 times over the first 4 years of marriage. Whereas husbands were more satisfied at the beginning of the marriage and remained more satisfied over the next 4 years to the extent that they had an attractive wife, wives were no more or less satisfied initially or over the next 4 years to the extent that they had an attractive husband. Most importantly, a direct test indicated that partner physical attractiveness played a larger role in predicting husbands' satisfaction than predicting wives' satisfaction. These findings strengthen support for the idea that sex differences in self-reported preferences for physical attractiveness do have implications for long-term relationship outcomes. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Scout trajectory error propagation computer program

NASA Technical Reports Server (NTRS)

Myler, T. R.

1982-01-01

Since 1969, flight experience has been used as the basis for predicting Scout orbital accuracy. The data used for calculating the accuracy consists of errors in the trajectory parameters (altitude, velocity, etc.) at stage burnout as observed on Scout flights. Approximately 50 sets of errors are used in Monte Carlo analysis to generate error statistics in the trajectory parameters. A covariance matrix is formed which may be propagated in time. The mechanization of this process resulted in computer program Scout Trajectory Error Propagation (STEP) and is described herein. Computer program STEP may be used in conjunction with the Statistical Orbital Analysis Routine to generate accuracy in the orbit parameters (apogee, perigee, inclination, etc.) based upon flight experience.

Overview and Software Architecture of the Copernicus Trajectory Design and Optimization System

NASA Technical Reports Server (NTRS)

Williams, Jacob; Senent, Juan S.; Ocampo, Cesar; Mathur, Ravi; Davis, Elizabeth C.

2010-01-01

The Copernicus Trajectory Design and Optimization System represents an innovative and comprehensive approach to on-orbit mission design, trajectory analysis and optimization. Copernicus integrates state of the art algorithms in optimization, interactive visualization, spacecraft state propagation, and data input-output interfaces, allowing the analyst to design spacecraft missions to all possible Solar System destinations. All of these features are incorporated within a single architecture that can be used interactively via a comprehensive GUI interface, or passively via external interfaces that execute batch processes. This paper describes the Copernicus software architecture together with the challenges associated with its implementation. Additionally, future development and planned new capabilities are discussed. Key words: Copernicus, Spacecraft Trajectory Optimization Software.

Situated Trajectories of Learning in Vocational Training Interactions

ERIC Educational Resources Information Center

de Saint-Georges, Ingrid; Filliettaz, Laurent

2008-01-01

This paper investigates smaller-scale transitions that are part of the longer-term processes of subjective transformation and adaptation to new professional competencies for learners in the field of vocational education. On the conceptual level, it proposes to view transitions as intermediate states in situated trajectories of learning. The notion…

Exploring Regularities and Dynamic Systems in L2 Development

ERIC Educational Resources Information Center

Lenzing, Anke

2015-01-01

This article focuses on a theoretical and empirical exploration of developmental trajectories and individual learner variation in second language (L2) acquisition. Taking a processability perspective, I view learner language as a dynamic system that includes predictable universal developmental trajectories as well as individual learner variation,…

Trajectories of Cigarette Smoking From Adolescence to Adulthood as Predictors of Unemployment Status

PubMed Central

Zhang, Chenshu; Burke, Lindsay; Brook, David W.

2014-01-01

Introduction: This longitudinal study examined the association between trajectories of cigarette smoking and unemployment across a 29-year time period from mean age 14 to mean age 43. Methods: Participants came from a community-based random sample of residents in 2 upstate New York counties. Data were collected at 7 timepoints. Results: Using growth mixture modeling, 5 trajectory groups of cigarette smokers were identified. The trajectory groups were as follows: heavy/continuous smokers, occasional smokers, late-starting smokers, quitters/decreasers, and nonsmokers. Multivariate logistic regression analysis was used to study the relationship between the participant’s trajectory group membership and unemployment in the fifth decade of life. The association was determined with controls for age, gender, current cigarette use, current alcohol use, current marijuana use, physical diseases, occupation, educational level, past unemployment experience, socioeconomic status measures of family of origin, depressive mood, and self-control from adolescence through the early 40s. The findings indicate that patterns of adolescent and young adult cigarette smoking have implications for later unemployment. Overall, the results showed that people who fell into the categories of heavy/continuous smokers (adjusted odds ratio [AOR] = 3.84) and occasional smokers (AOR = 4.03) were more likely to be unemployed at mean age 43 when compared with nonsmokers. There was no significant difference between the quitters/decreasers and the nonsmokers with respect to unemployment. Conclusions: Intervention programs designed to deal with unemployment should consider focusing on heavy/continuous and occasional cigarette smokers as risk factors for unemployment. PMID:24997307

Trajectory Determination for Chang 'e-3 Probe Soft-landing

NASA Astrophysics Data System (ADS)

Yezhi, S.; Huang, Y.

2017-12-01

On December 2, 2013, The Chang 'e-3 (ce-3) probe was successfully launched from a long march-3b carrier rocket at Xichang satellite launch center. After more than five days of flying, the probe was captured by the moon to 100 km by 100 km. The orbit maneuvered to 15 km by 100 km 4 days later. Finally, at 21:12 Beijing time on December 14, 2013, it landed at the junction of the Sinus Iridum and Mare Imbrium. In the ce-3 project, the combined test mode of the radio ranging measurement and very long baseline interferometry (VLBI) was used. The soft-landing was carried out in ce-3 mission for the sampling .The paper presents a new method of trajectory determination for soft landing and sampling returning for lunar probe by B spline approximation. By simulation and data processing of Chang'E-3(CE-3), it could be assumed that the accuracy of trajectory determination of soft landing is less than 100 meters in CE-3. It appears that the difference between the endpoint of trajectory and the location from image processed by NASA'S LRO is less than 50m .It confirms the method of soft landing trajectory determination provided by the paper is effective. The paper analyzes the dynamics and control characteristics of the sampling returning, provides the preliminary feasible trajectory determination method for soft landing and sampling return of Chang'E-5 (CE - 5).

Heterogeneity in Trajectories of Child Maltreatment Severity: A Two-Part Growth Mixture Model

PubMed Central

Yampolskaya, Svetlana; Greenbaum, Paul E.; Brown, C. Hendricks; Armstrong, Mary I.

2016-01-01

This study examined the trajectories of maltreatment severity and substantiation over a 24-month period among children (N = 82,396) with repeated maltreatment reports. Findings revealed two different longitudinal patterns. The first pattern, Elevated Severity, showed a higher level of maltreatment during the initial incident and increased maltreatment severity during subsequent incidents but the substantiation rates for this class decreased over time. The second pattern, Lowered Severity, showed a much lower level of severity, but the likelihood of substantiation increased over time. The Elevated Severity class was comprised of children with an elevated risk profile due to both individual and contextual risk factors including older age, female gender, caregivers’ substance use problems, and a higher number of previous maltreatment reports. Implications of the findings are discussed. PMID:26300381

Patterns and predictors of growth in divorced fathers' health status and substance use.

PubMed

DeGarmo, David S; Reid, John B; Leve, Leslie D; Chamberlain, Patricia; Knutson, John F

2010-03-01

Health status and substance use trajectories are described over 18 months for a county sample of 230 divorced fathers of young children aged 4 to 11. One third of the sample was clinically depressed. Health problems, drinking, and hard drug use were stable over time for the sample, whereas depression, smoking, and marijuana use exhibited overall mean reductions. Variance components revealed significant individual differences in average levels and trajectories for health and substance use outcomes. Controlling for fathers' antisociality, negative life events, and social support, fathering identity predicted reductions in health-related problems and marijuana use. Father involvement reduced drinking and marijuana use. Antisociality was the strongest risk factor for health and substance use outcomes. Implications for application of a generative fathering perspective in practice and preventive interventions are discussed.

Teacher performance goal practices and elementary students' behavioral engagement: a developmental perspective.

PubMed

Hughes, Jan N; Wu, Wei; West, Stephen G

2011-02-01

We investigated growth trajectories for classroom performance goal practices and for student behavioral engagement across grades 2 to 5 for 497 academically at-risk elementary students. This study is the first longitudinal investigation of performance goal practices in the early elementary years. On average, teacher use of performance goal practices increased and students' behavioral engagement declined across the four years. Using autoregressive latent trajectory (ALT) models, we examined the synchronous relations between teacher-reported performance goal practices and teacher-reported student behavioral engagement. As expected, as students move into classrooms with a new teacher with less emphasis on performance goal practices, they become more behaviorally engaged in school. Gender did not moderate these results. Implications for teacher professional development are discussed. Published by Elsevier Ltd.

Motor origins of tool use.

PubMed

Kahrs, Björn A; Jung, Wendy P; Lockman, Jeffrey J

2013-01-01

The current study examines the developmental trajectory of banging movements and its implications for tool use development. Twenty (6- to 15-month-old) infants wore reflective markers while banging a handled cube; movements were recorded at 240 Hz. Results indicated that through the second half-year, banging movements undergo developmental changes making them ideally suited for instrumental hammering and pounding. Younger infants were inefficient and variable when banging the object: Their hands followed circuitous paths of great lengths at high velocities. By 1 year, infants showed consistent and efficient straight up-down hand trajectories of smaller magnitude and velocity, allowing for precise aiming and delivering dependable levels of force. The findings suggest that tool use develops gradually from infants' existing manual behaviors. © 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.

Childhood predictors of lung function trajectories and future COPD risk: a prospective cohort study from the first to the sixth decade of life.

PubMed

Bui, Dinh S; Lodge, Caroline J; Burgess, John A; Lowe, Adrian J; Perret, Jennifer; Bui, Minh Q; Bowatte, Gayan; Gurrin, Lyle; Johns, David P; Thompson, Bruce R; Hamilton, Garun S; Frith, Peter A; James, Alan L; Thomas, Paul S; Jarvis, Deborah; Svanes, Cecilie; Russell, Melissa; Morrison, Stephen C; Feather, Iain; Allen, Katrina J; Wood-Baker, Richard; Hopper, John; Giles, Graham G; Abramson, Michael J; Walters, Eugene H; Matheson, Melanie C; Dharmage, Shyamali C

2018-04-05

Lifetime lung function is related to quality of life and longevity. Over the lifespan, individuals follow different lung function trajectories. Identification of these trajectories, their determinants, and outcomes is important, but no study has done this beyond the fourth decade. We used six waves of the Tasmanian Longitudinal Health Study (TAHS) to model lung function trajectories measured at 7, 13, 18, 45, 50, and 53 years. We analysed pre-bronchodilator FEV 1 z-scores at the six timepoints using group-based trajectory modelling to identify distinct subgroups of individuals whose measurements followed a similar pattern over time. We related the trajectories identified to childhood factors and risk of chronic obstructive pulmonary disease (COPD) using logistic regression, and estimated population-attributable fractions of COPD. Of the 8583 participants in the original cohort, 2438 had at least two waves of lung function data at age 7 years and 53 years and comprised the study population. We identified six trajectories: early below average, accelerated decline (97 [4%] participants); persistently low (136 [6%] participants); early low, accelerated growth, normal decline (196 [8%] participants); persistently high (293 [12%] participants); below average (772 [32%] participants); and average (944 [39%] participants). The three trajectories early below average, accelerated decline; persistently low; and below average had increased risk of COPD at age 53 years compared with the average group (early below average, accelerated decline: odds ratio 35·0, 95% CI 19·5-64·0; persistently low: 9·5, 4·5-20·6; and below average: 3·7, 1·9-6·9). Early-life predictors of the three trajectories included childhood asthma, bronchitis, pneumonia, allergic rhinitis, eczema, parental asthma, and maternal smoking. Personal smoking and active adult asthma increased the impact of maternal smoking and childhood asthma, respectively, on the early below average, accelerated decline trajectory. We identified six potential FEV 1 trajectories, two of which were novel. Three trajectories contributed 75% of COPD burden and were associated with modifiable early-life exposures whose impact was aggravated by adult factors. We postulate that reducing maternal smoking, encouraging immunisation, and avoiding personal smoking, especially in those with smoking parents or low childhood lung function, might minimise COPD risk. Clinicians and patients with asthma should be made aware of the potential long-term implications of non-optimal asthma control for lung function trajectory throughout life, and the role and benefit of optimal asthma control on improving lung function should be investigated in future intervention trials. National Health and Medical Research Council of Australia; European Union's Horizon 2020; The University of Melbourne; Clifford Craig Medical Research Trust of Tasmania; The Victorian, Queensland & Tasmanian Asthma Foundations; The Royal Hobart Hospital; Helen MacPherson Smith Trust; and GlaxoSmithKline. Copyright © 2018 Elsevier Ltd. All rights reserved.

The potential contribution of dietary factors to breast cancer prevention.

PubMed

Shapira, Niva

2017-09-01

Breast cancer (BC), the leading cancer in women, is increasing in prevalence worldwide, concurrent with western metabolic epidemics, that is, obesity, metabolic syndrome, and diabetes, and shares major risk factors with these diseases. The corresponding potential for nutritional contributions toward BC prevention is reviewed and related to critical stages in the life cycle and their implications for carcinogenic and pathometabolic trajectories. BC initiation potentially involves diet-related pro-oxidative, inflammatory, and procarcinogenic processes, that interact through combined lipid/fatty acid peroxidation, estrogen metabolism, and related DNA-adduct/depurination/mutation formation. The pathometabolic trajectory is affected by high estrogen, insulin, and growth factor cascades and resultant accelerated proliferation/progression. Anthropometric risk factors - high birth weight, adult tallness, adiposity/BMI, and weight gain - are often reflective of these trends. A sex-based nutritional approach targets women's specific risk in western obesogenic environments, associated with increasing fatness, estrogen metabolism, n-6 : n-3 polyunsaturated fatty acid ratio, and n-6 polyunsaturated fatty acid conversion to proinflammatory/carcinogenic eicosanoids, and effects of timing of life events, for example, ages at menarche, full-term pregnancy, and menopause. Recent large-scale studies have confirmed the effectiveness of the evidence-based recommendations against BC risk, emphasizing low-energy density diets, highly nutritious plant-based regimes, physical activity, and body/abdominal adiposity management. Better understanding of dietary inter-relationships with BC, as applied to food intake, selection, combination, and processing/preparation, and recommended patterns, for example, Mediterranean, DASH, plant-based, low energy density, and low glycemic load, with high nutrient/phytonutrient density, would increase public motivation and authoritative support for early/timely prevention, optimally merging with other dietary/health goals, for lifelong BC prevention.

Patterns of postnatal ontogeny of the skull and lower jaw of snakes as revealed by micro-CT scan data and three-dimensional geometric morphometrics.

PubMed

Palci, Alessandro; Lee, Michael S Y; Hutchinson, Mark N

2016-12-01

We compared the head skeleton (skull and lower jaw) of juvenile and adult specimens of five snake species [Anilios (=Ramphotyphlops) bicolor, Cylindrophis ruffus, Aspidites melanocephalus, Acrochordus arafurae, and Notechis scutatus] and two lizard outgroups (Ctenophorus decresii, Varanus gilleni). All major ontogenetic changes observed were documented both qualitatively and quantitatively. Qualitative comparisons were based on high-resolution micro-CT scanning of the specimens, and detailed quantitative analyses were performed using three-dimensional geometric morphometrics. Two sets of landmarks were used, one for accurate representation of the intraspecific transformations of each skull and jaw configuration, and the other for comparison between taxa. Our results document the ontogenetic elaboration of crests and processes for muscle attachment (especially for cervical and adductor muscles); negative allometry in the braincase of all taxa; approximately isometric growth of the snout of all taxa except Varanus and Anilios (positively allometric); and positive allometry in the quadrates of the macrostomatan snakes Aspidites, Acrochordus and Notechis, but also, surprisingly, in the iguanian lizard Ctenophorus. Ontogenetic trajectories from principal component analysis provide evidence for paedomorphosis in Anilios and peramorphosis in Acrochordus. Some primitive (lizard-like) features are described for the first time in the juvenile Cylindrophis. Two distinct developmental trajectories for the achievement of the macrostomatan (large-gaped) condition in adult snakes are documented, driven either by positive allometry of supratemporal and quadrate (in pythons), or of quadrate alone (in sampled caenophidians); this is consistent with hypothesised homoplasy in this adaptive complex. Certain traits (e.g. shape of coronoid process, marginal tooth counts) are more stable throughout postnatal ontogeny than others (e.g. basisphenoid keel), with implications for their reliability as phylogenetic characters. © 2016 Anatomical Society.

Profile negotiation: An air/ground automation integration concept for managing arrival traffic

NASA Technical Reports Server (NTRS)

Williams, David H.; Arbuckle, P. Douglas; Green, Steven M.; Denbraven, Wim

1993-01-01

NASA Ames Research Center and NASA Langley Research Center conducted a joint simulation study to evaluate a profile negotiation process (PNP) between a time-based air traffic control ATC system and an airplane equipped with a four dimensional flight management system (4D FMS). Prototype procedures were developed to support the functional implementation of this process. The PNP was designed to provide an arrival trajectory solution that satisfies the separation requirements of ATC while remaining as close as possible to the airplane's preferred trajectory. The Transport Systems Research Vehicle cockpit simulator was linked in real-time to the Center/TRACON Automation System (CTAS) for the experiment. Approximately 30 hours of simulation testing were conducted over a three week period. Active airline pilot crews and active Center controller teams participated as test subjects. Results from the experiment indicate the potential for successful incorporation of airplane preferred arrival trajectories in the CTAS automation environment. Controllers were able to consistently and effectively negotiate nominally conflict-free trajectories with pilots flying a 4D-FMS-equipped airplane. The negotiated trajectories were substantially closer to the airplane's preference than would have otherwise been possible without the PNP. Airplane fuel savings relative to baseline CTAS were achieved in the test scenarios. The datalink procedures and clearances developed for this experiment, while providing the necessary functionality, were found to be operationally unacceptable to the pilots. Additional pilot control and understanding of the proposed airplane-preferred trajectory and a simplified clearance procedure were cited as necessary for operational implementation of the concept. From the controllers' perspective, the main concerns were the ability of the 4D airplane to accurately track the negotiated trajectory and the workload required to support the PNP as implemented in this study.

An Automated Solution of the Low-Thrust Interplanetary Trajectory Problem.

PubMed

Englander, Jacob A; Conway, Bruce A

2017-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated, which can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a hybrid optimal control problem. The method is demonstrated on hypothetical missions to Mercury, the main asteroid belt, and Pluto.

Processing of Cells' Trajectories Data for Blood Flow Simulation Model*

NASA Astrophysics Data System (ADS)

Slavík, Martin; Kovalčíková, Kristína; Bachratý, Hynek; Bachratá, Katarína; Smiešková, Monika

2018-06-01

Simulations of the red blood cells (RBCs) flow as a movement of elastic objects in a fluid, are developed to optimize microfluidic devices used for a blood sample analysis for diagnostic purposes in the medicine. Tracking cell behaviour during simulation helps to improve the model and adjust its parameters. For the optimization of the microfluidic devices, it is also necessary to analyse cell trajectories as well as likelihood and frequency of their occurrence in a particular device area, especially in the parts, where they can affect circulating tumour cells capture. In this article, we propose and verify several ways of processing and analysing the typology and trajectory stability in simulations with single or with a large number of red blood cells (RBCs) in devices with different topologies containing cylindrical obstacles.

An Automated Solution of the Low-Thrust Interplanetary Trajectory Problem

NASA Technical Reports Server (NTRS)

Englander, Jacob A.; Conway, Bruce

2016-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated, which can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a hybrid optimal control problem. The method is demonstrated on hypothetical missions to Mercury, the main asteroid belt, and Pluto.

An Automated Solution of the Low-Thrust Interplanetary Trajectory Problem

PubMed Central

Englander, Jacob A.; Conway, Bruce A.

2017-01-01

Preliminary design of low-thrust interplanetary missions is a highly complex process. The mission designer must choose discrete parameters such as the number of flybys, the bodies at which those flybys are performed, and in some cases the final destination. In addition, a time-history of control variables must be chosen that defines the trajectory. There are often many thousands, if not millions, of possible trajectories to be evaluated, which can be a very expensive process in terms of the number of human analyst hours required. An automated approach is therefore very desirable. This work presents such an approach by posing the mission design problem as a hybrid optimal control problem. The method is demonstrated on hypothetical missions to Mercury, the main asteroid belt, and Pluto. PMID:29515289

Word Learning in Children with Autism Spectrum Disorders

PubMed Central

Luyster, Rhiannon; Lord, Catherine

2010-01-01

Autism Spectrum Disorders (ASD) have been gaining attention, partly as an example of unusual developmental trajectories related to early neurobiological differences. The present investigation addressed the process of learning new words in order to explore mechanisms of language delay and impairment. The sample included 21 typically developing toddlers matched on expressive vocabulary with 21 young children with ASD. Two tasks were administered to teach children a new word and were supplemented by cognitive and diagnostic measures. In most analyses, there were no group differences in performance. Children with ASD did not consistently make mapping errors, even in word learning situations which required the use of social information. These findings indicate that some children with ASD, in developmentally appropriate tasks, are able to use information from social interactions to guide word-object mappings. This result has important implications for our understanding of how children with ASD learn language. PMID:19899931

Performability evaluation of the SIFT computer

NASA Technical Reports Server (NTRS)

Meyer, J. F.; Furchtgott, D. G.; Wu, L. T.

1979-01-01

Performability modeling and evaluation techniques are applied to the SIFT computer as it might operate in the computational evironment of an air transport mission. User-visible performance of the total system (SIFT plus its environment) is modeled as a random variable taking values in a set of levels of accomplishment. These levels are defined in terms of four attributes of total system behavior: safety, no change in mission profile, no operational penalties, and no economic process whose states describe the internal structure of SIFT as well as relavant conditions of the environment. Base model state trajectories are related to accomplishment levels via a capability function which is formulated in terms of a 3-level model hierarchy. Performability evaluation algorithms are then applied to determine the performability of the total system for various choices of computer and environment parameter values. Numerical results of those evaluations are presented and, in conclusion, some implications of this effort are discussed.

Don't fight the site: three geomorphic considerations in catchment-scale river rehabilitation planning.

PubMed

Brierley, Gary; Fryirs, Kirstie

2009-06-01

Three geomorphic considerations that underpin the design and implementation of realistic and strategic river conservation and rehabilitation programs that work with the nature are outlined. First, the importance of appreciating the inherent diversity of river forms and processes is discussed. Second, river dynamics are appraised, framing the contemporary behavioral regime of a reach in relation to system evolution to explain changes to river character and behavior over time. Third, the trajectory of a reach is framed in relation to downstream patterns of river types, analyzing landscape connectivity at the catchment scale to interpret geomorphic river recovery potential. The application of these principles is demonstrated using extensive catchment-scale analyses of geomorphic river responses to human disturbance in the Bega and Upper Hunter catchments in southeastern Australia. Differing implications for reach- and catchment-scale rehabilitation planning prompt the imperative that management practices work with nature rather than strive to 'fight the site.'

A Conceptual Design of Omni-Directional Receiving Dual-Beam Laser Engine

NASA Astrophysics Data System (ADS)

Tang, Zhiping; Zhang, Qinghong

2010-05-01

The laser engine design is one of the key issues for laser propulsion technology. A concept of Omni-Directional Receiving Dual-Beam Laser Engine (ODLE) together with its configuration design is proposed in this paper. The ODLE is noted for its features as follows: First, the optical system is completely separated from the thrust system, the incident laser beams are reflected into the thrust chamber by the optics only twice, so the beam energy loss is small. Second, the optical system can be adjusted in all direction to track the incident laser beams, ensuring its wide applications in various kinds of launching trajectories. Third, the adoption of the dual-beam single-or double-engine configuration can reduce 50% of the power requirement for each laser, and a smooth laser relay can be carried out if needed during the launching process. The paper has proposed 2 launch plans into the LEO with the ODLE: the plane trajectory and the conic spiral trajectory. The simulated results indicate that the transmission distance of laser beams for the conic spiral trajectory is far less than that of the plane trajectory. As a result, it can reduce significantly the divergence and energy loss of laser beams, and is also of advantage for the measurement and control operation during the launch process.

Visual Uav Trajectory Plan System Based on Network Map

NASA Astrophysics Data System (ADS)

Li, X. L.; Lin, Z. J.; Su, G. Z.; Wu, B. Y.

2012-07-01

The base map of the current software UP-30 using in trajectory plan for Unmanned Aircraft Vehicle is vector diagram. UP-30 draws navigation points manually. But in the field of operation process, the efficiency and the quality of work is influenced because of insufficient information, screen reflection, calculate inconveniently and other factors. If we do this work in indoor, the effect of external factors on the results would be eliminated, the network earth users can browse the free world high definition satellite images through downloading a client software, and can export the high resolution image by standard file format. This brings unprecedented convenient of trajectory plan. But the images must be disposed by coordinate transformation, geometric correction. In addition, according to the requirement of mapping scale ,camera parameters and overlap degree we can calculate exposure hole interval and trajectory distance between the adjacent trajectory automatically . This will improve the degree of automation of data collection. Software will judge the position of next point according to the intersection of the trajectory and the survey area and ensure the position of point according to trajectory distance. We can undertake the points artificially. So the trajectory plan is automatic and flexible. Considering safety, the date can be used in flying after simulating flight. Finally we can export all of the date using a key

Significance of specific force models in two applications: Solar sails to sun-earth L4/L5 and grail data analysis suggesting lava tubes and buried craters on the moon

NASA Astrophysics Data System (ADS)

Sood, Rohan

In the trajectory design process, gravitational interaction between the bodies of interest plays a key role in developing the over-arching force model. However, non-gravitational forces, such as solar radiation pressure (SRP), can significantly influence the motion of a spacecraft. Incorporating SRP within the dynamical model can assist in estimating the trajectory of a spacecraft with greater precision, in particular, for a spacecraft with a large area-to-mass ratio, i.e., solar sails. Subsequently, in the trajectory design process, solar radiation pressure can be leveraged to maneuver the sail-based spacecraft. First, to construct low energy transfers, the invariant manifolds are explored that form an important tool in the computation and design of complex trajectories. The focus is the investigation of trajectory design options, incorporating solar sail dynamics, from the Earth parking orbit to the vicinity of triangular Lagrange points. Thereafter, an optimization scheme assisted in investigating the ?V requirement to depart from the Earth parking orbit. Harnessing the solar radiation pressure, the spacecraft is delivered to the vicinity of the displaced Lagrange point and maintains a trajectory close to the artificial libration point with the help of the solar sail. However, these trajectories are converged in a model formulated as a three-body problem with additional acceleration from solar radiation pressure. Thus, the trajectories are transitioned to higher fidelity ephemeris model to account for additional perturbing accelerations that may dominate the sail-craft dynamics and improve upon the trajectory design process. Alternatively, precise knowledge of the motion of a spacecraft about a central body and the contribution of the SRP can assist in deriving a highly accurate gravity field model. The high resolution gravity data can potentially assist in exploring the surface and subsurface properties of a particular body. With the goal of expanding human presence beyond Earth, sub-surface empty lava tubes on other worlds form ideal candidates for creating a permanent habitation environment safe from cosmic radiation, micrometeorite impacts and temperature extremes. In addition, gravitational analysis has also revealed large buried craters under thick piles of mare basalt, shedding light on Moon's dynamic and hostile past. In this work, gravity mapping observations from NASA's Gravity Recovery and Interior Laboratory (GRAIL) are employed to detect the presence of potential empty lava tubes and large impact craters buried beneath the lunar maria.

Employee reactions and adjustment to euthanasia-related work: identifying turning-point events through retrospective narratives.

PubMed

Reeve, Charlie L; Spitzmuller, Christiane; Rogelberg, Steven G; Walker, Alan; Schultz, Lisa; Clark, Olga

2004-01-01

This study used a retrospective narrative procedure to examine the critical events that influence reactions and adjustment to euthanasia-related work of 35 employees who have stayed in the animal care and welfare field for at least 2 years. The study analyzed adjustment trajectory graphs and interview notes to identify turning-point events that spurred either a positive or negative change in shelter workers' psychological well-being. Analysis of the identified turning-point events revealed 10 common event themes that have implications for a range of work, personnel, and organizational practices. The article discusses implications for shelter, employee, and animal welfare.

A Real-Time Brain-Machine Interface Combining Motor Target and Trajectory Intent Using an Optimal Feedback Control Design

PubMed Central

Shanechi, Maryam M.; Williams, Ziv M.; Wornell, Gregory W.; Hu, Rollin C.; Powers, Marissa; Brown, Emery N.

2013-01-01

Real-time brain-machine interfaces (BMI) have focused on either estimating the continuous movement trajectory or target intent. However, natural movement often incorporates both. Additionally, BMIs can be modeled as a feedback control system in which the subject modulates the neural activity to move the prosthetic device towards a desired target while receiving real-time sensory feedback of the state of the movement. We develop a novel real-time BMI using an optimal feedback control design that jointly estimates the movement target and trajectory of monkeys in two stages. First, the target is decoded from neural spiking activity before movement initiation. Second, the trajectory is decoded by combining the decoded target with the peri-movement spiking activity using an optimal feedback control design. This design exploits a recursive Bayesian decoder that uses an optimal feedback control model of the sensorimotor system to take into account the intended target location and the sensory feedback in its trajectory estimation from spiking activity. The real-time BMI processes the spiking activity directly using point process modeling. We implement the BMI in experiments consisting of an instructed-delay center-out task in which monkeys are presented with a target location on the screen during a delay period and then have to move a cursor to it without touching the incorrect targets. We show that the two-stage BMI performs more accurately than either stage alone. Correct target prediction can compensate for inaccurate trajectory estimation and vice versa. The optimal feedback control design also results in trajectories that are smoother and have lower estimation error. The two-stage decoder also performs better than linear regression approaches in offline cross-validation analyses. Our results demonstrate the advantage of a BMI design that jointly estimates the target and trajectory of movement and more closely mimics the sensorimotor control system. PMID:23593130

Adolescent athletes with learning disability display atypical maturational trajectories on concussion baseline testing: Implications based on a Finnish sample.

PubMed

Peltonen, Kati; Vartiainen, Matti; Laitala-Leinonen, Tiina; Koskinen, Sanna; Luoto, Teemu; Pertab, Jon; Hokkanen, Laura

2018-05-21

Previous research has reported lower cognitive test scores on baseline testing in athletes reporting multiple previous concussions or a history of learning disability (LD). Age also has an important influence on cognitive performance. While these factors have been considered individually in previous studies, the present study is the first to explore the interaction of age, self-reported LD, and history of concussion on baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT®) in a nationwide study of adolescent athletes. ImPACT® was administered to 1823 Finnish male ice hockey players (aged 12-21 years old) prior to the 2015-2016 or 2016-2017 playing seasons. Linear regressions and simple slopes analyses were used for clarifying the impact of LD and previous concussion history on maturational trajectories. In comparison to typically developing athletes, athletes with LD had lower neurocognitive scores in all composites and differing maturational trajectory in verbal memory and visual motor speed. The number of previous concussions did not impair neurocognitive performance at baseline assessment. Application of standard age-based norms to adolescent athletes with a history of LD has the potential to negatively skew clinical decision-making. Separate reference values for LD athletes are warranted due to their unique developmental cognitive trajectories. The reference values for the Finnish participants in this study are presented.

Exploring Spirituality in Family Caregivers of Patients With Primary Malignant Brain Tumors Across the Disease Trajectory

PubMed Central

Newberry, Alyssa G.; Jean Choi, Chien-Wen; Donovan, Heidi S.; Schulz, Richard; Bender, Catherine; Given, Barbara; Sherwood, Paula

2013-01-01

Purpose/Objectives To determine whether the perceived level of spirituality in family caregivers of patients with primary malignant brain tumors (PMBTs) changes across the disease trajectory. Design Ongoing descriptive, longitudinal study. Setting Southwestern Pennsylvania. Sample 50 family caregivers of patients with PMBT. Methods Caregivers and care recipients were recruited at time of diagnosis. Participants were interviewed at two subse-quent time points, four and eight months following diagnosis. Main Research Variables Care recipients’ symptoms, neuro-psychologic status, and physical function, as well as caregiver social support. Findings Results showed no significant difference in spirituality scores reported at baseline and eight months (p = 0.8), suggesting that spirituality may be a stable trait across the disease trajectory. Conclusions Spirituality remains relatively stable along the course of the disease trajectory. Reports of caregiver depressive symptoms and anxiety were lower when paired with higher reports of spirituality. Implications for Nursing Clinicians can better identify caregivers at risk for negative outcomes by identifying those who report lower levels of spirituality. Future interventions should focus on the development and implementation of interventions that provide protective buffers such as increased social support. Knowledge Translation Spirituality is a relatively stable trait. High levels of spirituality can serve as a protective buffer from negative mental health outcomes. Caregivers with low levels of spirituality may be at risk for greater levels of burden, anxiety, and stress. PMID:23615145

Trajectories of emotional well-being in mothers of adolescents and adults with autism.

PubMed

Barker, Erin T; Hartley, Sigan L; Seltzer, Marsha Mailick; Floyd, Frank J; Greenberg, Jan S; Orsmond, Gael I

2011-03-01

Raising an adolescent or adult child with a developmental disability confers exceptional caregiving challenges on parents. We examined trajectories of 2 indicators of emotional well-being (depressive symptoms and anxiety) in a sample of primarily Caucasian mothers (N = 379; M age = 51.22 years at Time 1) of adolescent and adult children with an autism spectrum disorder (ASD; M age = 21.91 years at Time 1, 73.2% male). We also investigated within-person associations of child context time-varying covariates (autism symptoms, behavior problems, residential status) and maternal context time-varying covariates (social support network size and stressful family events) with the trajectories of emotional well-being. Data were collected on 5 occasions across a 10-year period. Average patterns of stable (depressive symptoms) and improved (anxiety) emotional well-being were evident, and well-being trajectories were sensitive to fluctuations in both child and maternal context variables. On occasions when behavior problems were higher, depressive symptoms and anxiety were higher. On occasions after which the grown child moved out of the family home, anxiety was lower. Anxiety was higher on occasions when social support networks were smaller and when more stressful life events were experienced. These results have implications for midlife and aging families of children with an ASD and those who provide services to these families. PsycINFO Database Record (c) 2011 APA, all rights reserved.

Long-term recovery trajectory after stroke: an ongoing negotiation between body, participation and self.

PubMed

Arntzen, Cathrine; Borg, Tove; Hamran, Torunn

2015-01-01

Research has mainly focused on the first year of recovery trajectory after stroke, but there is limited knowledge about how stroke survivors manage their long-term everyday lives. This study seeks to fill this gap by exploring the long-term (1-13 years) negotiations of stroke survivors when they experience progress, wellbeing and faith in the future. Repeated in-depth interviews were conducted with nine people living with moderate impairment after stroke and their closest relatives. Concepts from phenomenology and critical psychology constituted the frame of reference of the study. The long-term stroke recovery trajectory can be understood as a process of struggling to overcome tensions between three phenomena under ongoing change: the lived body, participation in everyday life and sense of self. During the recovery process, stroke survivors experience progress, well-being and faith in the future when moving towards renewed relationships, characterised by (1) a modified habitual body, (2) repositioned participation in specific everyday life contexts and (3) a transformed sense of self. This study stresses the importance of developing new forms of professional support during the long-term recovery trajectory, to stimulate and increase interaction and coherence in the relationship between the stroke survivor's bodily perception, participation in everyday life and sense of self. The study deepening how the long-term recovery trajectory after stroke is about ongoing embodied, practical and socially situated negotiations. The study demonstrates that the recovery trajectory is a long term process of learning where the stroke survivor, as an embodied agent, gradually modifies new bodily habits, re-position participation and transforming of the self. Health personnel are usually available in the acute and early rehabilitation period. The three phenomenons under ongoing change; "body", "participation" and "self" are at this point just about being moved toward a renewed and a more coherent relationship in the stroke survivor long-lasting everyday life situated recovery trajectory. Available rehabilitation services at the municipal level supporting stroke survivors and relatives practical, social and interpersonal long-term challenges in everyday life can be important for minimizing their struggles and for promoting the experience progress, wellbeing and faith in the future.

The education of scientists: Gender differences during the early life course

NASA Astrophysics Data System (ADS)

Shauman, Kimberlee Akin

In this dissertation, I examine gender differences in the science and engineering (S/E) educational trajectory--the pre-college and college experiences that lead to specialized education and qualification for an S/E occupation. This research makes important contributions by providing detailed and updated information about gender differences in the timing and causal mechanisms for flows into and out of the S/E educational trajectory. By using longitudinal data to model the linkages between past and future science experiences, I measure the dynamic process underlying the S/E educational trajectory and challenge the predominant "science pipeline" conceptualization of this process. I use the life course perspective as a guide to conceptualizing the S/E trajectory and to analyzing the social forces that shape the educational and career goals of individual women and men. I develop a conceptual model that specifies how the effects of a set of social influences gradually shift in measurable and predictable ways over the educational "life histories" of individuals. The causal factors in the model are (1) individual influences such as ability and attitudes, (2) familial influences, and (3) the influence of significant others in the social structure. To uncover gender differences in the process of becoming a scientist, I use four nationally representative longitudinal studies: the National Education Longitudinal Study of 1988, the Longitudinal Study of American Youth, the High School and Beyond, and the National Longitudinal Study of the Class of 1972. The empirical analyses of this dissertation focus on the individual and familial influences on participation in the S/E educational trajectory. Past experience in S/E education increases the likelihood of future participation, but persistence in the S/E trajectory is not the only viable route to S/E degree attainment. Entry into S/E majors during college is common, and it is a prevalent path to an S/E bachelor's degree, especially for women. The transition from high school to college is the point where the educational paths of males and females diverge significantly. Expectations about future family roles have the greatest influence on the gender differences in the patterns of participation in the S/E educational trajectory.

Trajectory-based understanding of the quantum-classical transition for barrier scattering

NASA Astrophysics Data System (ADS)

Chou, Chia-Chun

2018-06-01

The quantum-classical transition of wave packet barrier scattering is investigated using a hydrodynamic description in the framework of a nonlinear Schrödinger equation. The nonlinear equation provides a continuous description for the quantum-classical transition of physical systems by introducing a degree of quantumness. Based on the transition equation, the transition trajectory formalism is developed to establish the connection between classical and quantum trajectories. The quantum-classical transition is then analyzed for the scattering of a Gaussian wave packet from an Eckart barrier and the decay of a metastable state. Computational results for the evolution of the wave packet and the transmission probabilities indicate that classical results are recovered when the degree of quantumness tends to zero. Classical trajectories are in excellent agreement with the transition trajectories in the classical limit, except in some regions where transition trajectories cannot cross because of the single-valuedness of the transition wave function. As the computational results demonstrate, the process that the Planck constant tends to zero is equivalent to the gradual removal of quantum effects originating from the quantum potential. This study provides an insightful trajectory interpretation for the quantum-classical transition of wave packet barrier scattering.

Trajectories of women's abortion-related care: A conceptual framework.

PubMed

Coast, Ernestina; Norris, Alison H; Moore, Ann M; Freeman, Emily

2018-03-01

We present a new conceptual framework for studying trajectories to obtaining abortion-related care. It assembles for the first time all of the known factors influencing a trajectory and encourages readers to consider the ways these macro- and micro-level factors operate in multiple and sometimes conflicting ways. Based on presentation to and feedback from abortion experts (researchers, providers, funders, policymakers and advisors, advocates) (n = 325) between 03/06/2014 and 22/08/2015, and a systematic mapping of peer-reviewed literature (n = 424) published between 01/01/2011 and 30/10/2017, our framework synthesises the factors shaping abortion trajectories, grouped into three domains: abortion-specific experiences, individual contexts, and (inter)national and sub-national contexts. Our framework includes time-dependent processes involved in an individual trajectory, starting with timing of pregnancy awareness. This framework can be used to guide testable hypotheses about enabling and inhibiting influences on care-seeking behaviour and consideration about how abortion trajectories might be influenced by policy or practice. Research based on understanding of trajectories has the potential to improve women's experiences and outcomes of abortion-related care. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

A new paradigm for atomically detailed simulations of kinetics in biophysical systems.

PubMed

Elber, Ron

2017-01-01

The kinetics of biochemical and biophysical events determined the course of life processes and attracted considerable interest and research. For example, modeling of biological networks and cellular responses relies on the availability of information on rate coefficients. Atomically detailed simulations hold the promise of supplementing experimental data to obtain a more complete kinetic picture. However, simulations at biological time scales are challenging. Typical computer resources are insufficient to provide the ensemble of trajectories at the correct length that is required for straightforward calculations of time scales. In the last years, new technologies emerged that make atomically detailed simulations of rate coefficients possible. Instead of computing complete trajectories from reactants to products, these approaches launch a large number of short trajectories at different positions. Since the trajectories are short, they are computed trivially in parallel on modern computer architecture. The starting and termination positions of the short trajectories are chosen, following statistical mechanics theory, to enhance efficiency. These trajectories are analyzed. The analysis produces accurate estimates of time scales as long as hours. The theory of Milestoning that exploits the use of short trajectories is discussed, and several applications are described.

Seasonal Variations of the James Webb Space Telescope Orbital Dynamics

NASA Technical Reports Server (NTRS)

Brown, Jonathan; Petersen, Jeremy; Villac, Benjamin; Yu, Wayne

2015-01-01

While spacecraft orbital variations due to the Earth's tilt and orbital eccentricity are well-known phenomena, the implications for the James Webb Space Telescope present unique features. We investigate the variability of the observatory trajectory characteristics, and present an explanation of some of these effects using invariant manifold theory and local approximation of the dynamics in terms of the restricted three-body problem.

Equity: Policy Rhetoric or a Matter of Meaning of Knowledge? Towards a Framework for Tracing the "Efficiency-Equity" Doctrine in Curriculum Documents

ERIC Educational Resources Information Center

Wahlstrom, Ninni

2014-01-01

In this article, the focus is on exploring the perspective of equity in curriculum. From a background of understanding curriculum as embedded in wider transnational policy movements, in this article the author suggests a framework for exploring the trajectories between equity policy and different types of curricula with implications for what…

The Effects of Health Insurance Coverage on the Math Achievement Trajectories of School Children in Yuma County, Arizona: Implications for Education Accountability Policy

ERIC Educational Resources Information Center

Garcy, Anthony M.

2013-01-01

U.S. Federal and state education policies place considerable emphasis on assessing the effects that schools and teachers have on student test score performance. It is important for education policy makers to also consider other factors that can affect student achievement. This study finds that an exogenous school factor, discontinuous health…

Operating without a Safety Net: Gay Male Adolescents and Emerging Adults' Experiences of Marginalization and Migration, and Implications for Theory of Syndemic Production of Health Disparities

ERIC Educational Resources Information Center

Bruce, Douglas; Harper, Gary W.

2011-01-01

Health disparities among gay men (HIV, substance use, depression) have been described as a mutually occurring "syndemic" that is socially produced through two overarching dynamics: marginalization and migration. Although the syndemic theory proposes a developmental trajectory, it has been largely based on epidemiological studies of adult gay men…

Scramjet Nozzles

DTIC Science & Technology

2010-09-01

and y, the axial and radial coordinates respectively. Point c lies somewhere within the mesh generated by the initial expansion (the kernel). All that...and the surface will be subjected to high heat loads restricting the choice of suitable materials. Material choice has direct implications for...Some legacy trajectory codes might not be able to deal with anything other than axial forces from engines, reflecting the class of problem they were

Human body motion capture from multi-image video sequences

NASA Astrophysics Data System (ADS)

D'Apuzzo, Nicola

2003-01-01

In this paper is presented a method to capture the motion of the human body from multi image video sequences without using markers. The process is composed of five steps: acquisition of video sequences, calibration of the system, surface measurement of the human body for each frame, 3-D surface tracking and tracking of key points. The image acquisition system is currently composed of three synchronized progressive scan CCD cameras and a frame grabber which acquires a sequence of triplet images. Self calibration methods are applied to gain exterior orientation of the cameras, the parameters of internal orientation and the parameters modeling the lens distortion. From the video sequences, two kinds of 3-D information are extracted: a three-dimensional surface measurement of the visible parts of the body for each triplet and 3-D trajectories of points on the body. The approach for surface measurement is based on multi-image matching, using the adaptive least squares method. A full automatic matching process determines a dense set of corresponding points in the triplets. The 3-D coordinates of the matched points are then computed by forward ray intersection using the orientation and calibration data of the cameras. The tracking process is also based on least squares matching techniques. Its basic idea is to track triplets of corresponding points in the three images through the sequence and compute their 3-D trajectories. The spatial correspondences between the three images at the same time and the temporal correspondences between subsequent frames are determined with a least squares matching algorithm. The results of the tracking process are the coordinates of a point in the three images through the sequence, thus the 3-D trajectory is determined by computing the 3-D coordinates of the point at each time step by forward ray intersection. Velocities and accelerations are also computed. The advantage of this tracking process is twofold: it can track natural points, without using markers; and it can track local surfaces on the human body. In the last case, the tracking process is applied to all the points matched in the region of interest. The result can be seen as a vector field of trajectories (position, velocity and acceleration). The last step of the process is the definition of selected key points of the human body. A key point is a 3-D region defined in the vector field of trajectories, whose size can vary and whose position is defined by its center of gravity. The key points are tracked in a simple way: the position at the next time step is established by the mean value of the displacement of all the trajectories inside its region. The tracked key points lead to a final result comparable to the conventional motion capture systems: 3-D trajectories of key points which can be afterwards analyzed and used for animation or medical purposes.

The developmental dynamics of gait maturation with a focus on spatiotemporal measures.

PubMed

Kraan, C M; Tan, A H J; Cornish, K M

2017-01-01

Gait analysis is recognised as a powerful clinical tool for studying relationships between motor control and brain function. By drawing on the literature investigating gait in individuals with neurological disorders, this review provides insight into the neural processes that contribute to and regulate specific spatiotemporal sub-components of gait and how they may mature across early to late childhood. This review also discusses the roles of changing anthropomorphic characteristics, and maturing sensory and higher-order cognitive processes in differentiating the developmental trajectories of the sub-components of gait. Importantly, although studies have shown that cognitive-gait interference is larger in children compared to adults, the contributing neurocognitive mechanisms may vary across age groups who have different types of attentional or cognitive vulnerabilities. These findings have implications for current models of gait maturation by highlighting the need for a dynamic model that focuses on the integration of various factors that contribute to gait though experience and practice. This is essential to elucidating why gait and other motor deficits are often contiguous with cognitive neurodevelopmental disorders. Copyright © 2016. Published by Elsevier B.V.

Rape as an Economic Crime: The Impact of Sexual Violence on Survivors' Employment and Economic Well-Being.

PubMed

Loya, Rebecca M

2015-10-01

This article examines how isolated instances of sexual violence affect adult female survivors' employment and economic well-being. This study draws on data from 27 in-depth, qualitative interviews with sexual assault survivors and rape crisis service providers. The findings suggest that sexual assault and the related trauma response can disrupt survivors' employment in several ways, including time off, diminished performance, job loss, and inability to work. By disrupting income or reducing earning power, all of these employment consequences have implications for survivors' economic well-being in the months or years following the assault. In addition, I argue that for many survivors, these employment consequences compound one another and ultimately shift survivors' long-term economic trajectories. By highlighting survivors' lived experiences of the financial aftermath of sexual assault, these findings help to illuminate the processes by which sexual violence decreases survivors' income over the life course. Understanding the financial effects of sexual violence can help researchers better understand and predict the recovery process, while helping practitioners to design more effective interventions for survivors. © The Author(s) 2014.

Climate and demography in early prehistory: using calibrated (14)C dates as population proxies.

PubMed

Riede, Felix

2009-04-01

Although difficult to estimate for prehistoric hunter-gatherer populations, demographic variables-population size, density, and the connectedness of demes-are critical for a better understanding of the processes of material culture change, especially in deep prehistory. Demography is the middle-range link between climatic changes and both biological and cultural evolutionary trajectories of human populations. Much of human material culture functions as a buffer against climatic changes, and the study of prehistoric population dynamics, estimated through changing frequencies of calibrated radiocarbon dates, therefore affords insights into how effectively such buffers operated and when they failed. In reviewing a number of case studies (Mesolithic Ireland, the origin of the Bromme culture, and the earliest late glacial human recolonization of southern Scandinavia), I suggest that a greater awareness of demographic processes, and in particular of demographic declines, provides many fresh insights into what structured the archaeological record. I argue that we cannot sideline climatic and environmental factors or extreme geophysical events in our reconstructions of prehistoric culture change. The implications of accepting demographic variability as a departure point for evaluating the archaeological record are discussed.

Understanding the Etiology of Prescription Opioid Abuse: Implications for Prevention and Treatment

PubMed Central

Rigg, Khary K.; Murphy, John W.

2013-01-01

Although studies on the initiation of substance abuse abound, the body of literature on prescription opioid abuse (POA) etiology is small. Little is known about why and how the onset of POA occurs, especially among high-risk populations. In this study we aimed to fill this important knowledge gap by exploring the POA initiation experiences of 90 prescription opioid abusers currently in treatment and their narrative accounts of the circumstances surrounding their POA onset. This research was conducted within a storyline framework, which operates on the premise that the path to drug abuse represents a biography or a process rather than a static condition. Audiotapes of in-depth interviews were transcribed, coded, and thematically analyzed. Analyses revealed the presence of four trajectories leading to POA. This study adds to the limited research on POA etiology by not only illuminating the psychosocial factors that contribute to POA onset, but also by situating initiation experiences within broader life processes. The study findings provide crucial insights to policymakers and interventionists in identifying who is at risk for POA, and more important, when and how to intervene most efficaciously. PMID:23656723

Understanding the etiology of prescription opioid abuse: implications for prevention and treatment.

PubMed

Rigg, Khary K; Murphy, John W

2013-07-01

Although studies on the initiation of substance abuse abound, the body of literature on prescription opioid abuse (POA) etiology is small. Little is known about why and how the onset of POA occurs, especially among high-risk populations. In this study we aimed to fill this important knowledge gap by exploring the POA initiation experiences of 90 prescription opioid abusers currently in treatment and their narrative accounts of the circumstances surrounding their POA onset. This research was conducted within a storyline framework, which operates on the premise that the path to drug abuse represents a biography or a process rather than a static condition. Audiotapes of in-depth interviews were transcribed, coded, and thematically analyzed. Analyses revealed the presence of four trajectories leading to POA. This study adds to the limited research on POA etiology by not only illuminating the psychosocial factors that contribute to POA onset, but also by situating initiation experiences within broader life processes. The study findings provide crucial insights to policymakers and interventionists in identifying who is at risk for POA, and more important, when and how to intervene most efficaciously.

"Simply the Best for My Children": Patterns of Parental Involvement in Education

ERIC Educational Resources Information Center

Ule, Mirjana; Živoder, Andreja; du Bois-Reymond, Manuela

2015-01-01

This article explores parental involvement in the educational trajectories of children in Europe. The analysis is embedded in the framework of the three dominant contemporary social processes that have been acknowledged as crucial factors for the educational and life trajectories of young people today, i.e. familialization, institutionalization,…

Innovation Becoming Trajectories: Leveraging Lateral and Vertical Moves for Collaborative Diffusion of Twenty-First Century Learning Practices

ERIC Educational Resources Information Center

Hung, David; Toh, Yancy; Jamaludin, Azilawati; So, Hyo-Jeong

2017-01-01

This paper argues for innovation diffusion as a "becoming" process in the context of lateral and vertical moves. The context of these innovations involves technology-mediated innovations and their diffusion trajectories in the Singapore education system. Embedded in a centralized-decentralized dialectics, this paper traces particular…

Developmental Trajectories for Children with Dyslexia and Low IQ Poor Readers

ERIC Educational Resources Information Center

Kuppen, Sarah E. A.; Goswami, Usha

2016-01-01

Reading difficulties are found in children with both high and low IQ and it is now clear that both groups exhibit difficulties in phonological processing. Here, we apply the developmental trajectories approach, a new methodology developed for studying language and cognitive impairments in developmental disorders, to both poor reader groups. The…

Developmental Trajectories of Form Perception: A Story of Attention

ERIC Educational Resources Information Center

Kovshoff, Hanna; Iarocci, Grace; Shore, David I.; Burack, Jacob A.

2015-01-01

The developmental trajectories of selective and divided attention were examined in relation to the processing of hierarchically integrated stimuli. The participants included children in 4 age groups (6, 8, 10, and 12 years) and a group of young adults (24 years) who completed 2 computer-based attention tasks. In the selective attention task, the…

Automatic Associations and Panic Disorder: Trajectories of Change over the Course of Treatment

ERIC Educational Resources Information Center

Teachman, Bethany A.; Marker, Craig D.; Smith-Janik, Shannan B.

2008-01-01

Cognitive models of anxiety and panic suggest that symptom reduction during treatment should be preceded by changes in cognitive processing, including modifying the anxious schema. The current study tested these hypotheses by using a repeated measures design to evaluate whether the trajectory of change in automatic panic associations over a…

MDTRA: a molecular dynamics trajectory analyzer with a graphical user interface.

PubMed

Popov, Alexander V; Vorobjev, Yury N; Zharkov, Dmitry O

2013-02-05

Most of existing software for analysis of molecular dynamics (MD) simulation results is based on command-line, script-guided processes that require the researchers to have an idea about programming language constructions used, often applied to the one and only product. Here, we describe an open-source cross-platform program, MD Trajectory Reader and Analyzer (MDTRA), that performs a large number of MD analysis tasks assisted with a graphical user interface. The program has been developed to facilitate the process of search and visualization of results. MDTRA can handle trajectories as sets of protein data bank files and presents tools and guidelines to convert some other trajectory formats into such sets. The parameters analyzed by MDTRA include interatomic distances, angles, dihedral angles, angles between planes, one-dimensional and two-dimensional root-mean-square deviation, solvent-accessible area, and so on. As an example of using the program, we describe the application of MDTRA to analyze the MD of formamidopyrimidine-DNA glycosylase, a DNA repair enzyme from Escherichia coli. Copyright © 2012 Wiley Periodicals, Inc.

Associations between infant feeding and the size, tempo and velocity of infant weight gain: SITAR analysis of the Gemini twin birth cohort

PubMed Central

Johnson, L; van Jaarsveld, C H M; Llewellyn, C H; Cole, T J; Wardle, J

2014-01-01

Objective: Infant growth trajectories, in terms of size, tempo and velocity, may programme lifelong obesity risk. Timing of breastfeeding cessation and weaning are both implicated in rapid infant growth; we examined the association of both simultaneously with a range of growth parameters. Design: Longitudinal population-based twin birth cohort. Subjects: The Gemini cohort provided data on 4680 UK infants with a median of 10 (interquartile range=8–15) weight measurements between birth and a median of 6.5 months. Age at breastfeeding cessation and weaning were reported by parents at mean age 8.2 months (s.d.=2.2, range=4–20). Growth trajectories were modelled using SuperImposition by Translation And Rotation (SITAR) to generate three descriptors of individual growth relative to the average trajectory: size (grams), tempo (weeks, indicating the timing of the peak growth rate) and velocity (% difference from average, reflecting mean growth rate). Complex-samples general linear models adjusting for family clustering and confounders examined associations between infant feeding and SITAR parameters. Results: Longer breastfeeding (>4 months vs never) was independently associated with lower growth velocity by 6.8% (s.e.=1.3%) and delayed growth tempo by 1.0 (s.e.=0.2 weeks), but not with smaller size. Later weaning (⩾6 months vs <4 months) was independently associated with lower growth velocity by 4.9% (s.e.=1.1%) and smaller size by 102 g (s.e.=25 g). Conclusions: Infants breastfed for longer grew slower for longer after birth (later peak growth rate) but were no different in size, while infants weaned later grew slower overall and were smaller but the timing of peak growth did not differ. Slower trajectories with a delayed peak in growth may have beneficial implications for programming later obesity risk. Replication in cohorts with longer follow-up, alternative confounding structures or randomised controlled trials are required to confirm the long-term effects and directionality, and to rule out residual confounding. PMID:24722545

Route Sanitizer: Connected Vehicle Trajectory De-Identification Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, Jason M; Ferber, Aaron E

Route Sanitizer is ORNL's connected vehicle moving object database de-identification tool and a graphical user interface to ORNL's connected vehicle de-identification algorithm. It uses the Google Chrome (soon to be Electron) platform so it will run on different computing platforms. The basic de-identification strategy is record redaction: portions of a vehicle trajectory (e.g. sequences of precise temporal spatial records) are removed. It does not alter retained records. The algorithm uses custom techniques to find areas within trajectories that may be considered private, then it suppresses those in addition to enough of the trajectory surrounding those locations to protect against "inferencemore » attacks" in a mathematically sound way. Map data is integrated into the process to make this possible.« less

Free Surface Downgoing VSP Multiple Imaging

NASA Astrophysics Data System (ADS)

Maula, Fahdi; Dac, Nguyen

2018-03-01

The common usage of a vertical seismic profile is to capture the reflection wavefield (upgoing wavefield) so that it can be used for further well tie or other interpretations. Borehole Seismic (VSP) receivers capture the reflection from below the well trajectory, traditionally no seismic image information above trajectory. The non-traditional way of processing the VSP multiple can be used to expand the imaging above the well trajectory. This paper presents the case study of using VSP downgoing multiples for further non-traditional imaging applications. In general, VSP processing, upgoing and downgoing arrivals are separated during processing. The up-going wavefield is used for subsurface illumination, whereas the downgoing wavefield and multiples are normally excluded from the processing. In a situation where the downgoing wavefield passes the reflectors several times (multiple), the downgoing wavefield carries reflection information. Its benefit is that it can be used for seismic tie up to seabed, and possibility for shallow hazards identifications. One of the concepts of downgoing imaging is widely known as mirror-imaging technique. This paper presents a case study from deep water offshore Vietnam. The case study is presented to demonstrate the robustness of the technique, and the limitations encountered during its processing.

Development and evaluation of a profile negotiation process for integrating aircraft and air traffic control automation

NASA Technical Reports Server (NTRS)

Green, Steven M.; Denbraven, Wim; Williams, David H.

1993-01-01

The development and evaluation of the profile negotiation process (PNP), an interactive process between an aircraft and air traffic control (ATC) that integrates airborne and ground-based automation capabilities to determine conflict-free trajectories that are as close to an aircraft's preference as possible, are described. The PNP was evaluated in a real-time simulation experiment conducted jointly by NASA's Ames and Langley Research Centers. The Ames Center/TRACON Automation System (CTAS) was used to support the ATC environment, and the Langley Transport Systems Research Vehicle (TSRV) piloted cab was used to simulate a 4D Flight Management System (FMS) capable aircraft. Both systems were connected in real time by way of voice and data lines; digital datalink communications capability was developed and evaluated as a means of supporting the air/ground exchange of trajectory data. The controllers were able to consistently and effectively negotiate nominally conflict-free vertical profiles with the 4D-equipped aircraft. The actual profiles flown were substantially closer to the aircraft's preference than would have been possible without the PNP. However, there was a strong consensus among the pilots and controllers that the level of automation of the PNP should be increased to make the process more transparent. The experiment demonstrated the importance of an aircraft's ability to accurately execute a negotiated profile as well as the need for digital datalink to support advanced air/ground data communications. The concept of trajectory space is proposed as a comprehensive approach for coupling the processes of trajectory planning and tracking to allow maximum pilot discretion in meeting ATC constraints.

Trajectory Design Employing Convex Optimization for Landing on Irregularly Shaped Asteroids

NASA Technical Reports Server (NTRS)

Pinson, Robin M.; Lu, Ping

2016-01-01

Mission proposals that land on asteroids are becoming popular. However, in order to have a successful mission the spacecraft must reliably and softly land at the intended landing site. The problem under investigation is how to design a fuel-optimal powered descent trajectory that can be quickly computed on- board the spacecraft, without interaction from ground control. An optimal trajectory designed immediately prior to the descent burn has many advantages. These advantages include the ability to use the actual vehicle starting state as the initial condition in the trajectory design and the ease of updating the landing target site if the original landing site is no longer viable. For long trajectories, the trajectory can be updated periodically by a redesign of the optimal trajectory based on current vehicle conditions to improve the guidance performance. One of the key drivers for being completely autonomous is the infrequent and delayed communication between ground control and the vehicle. Challenges that arise from designing an asteroid powered descent trajectory include complicated nonlinear gravity fields, small rotating bodies and low thrust vehicles. There are two previous studies that form the background to the current investigation. The first set looked in-depth at applying convex optimization to a powered descent trajectory on Mars with promising results.1, 2 This showed that the powered descent equations of motion can be relaxed and formed into a convex optimization problem and that the optimal solution of the relaxed problem is indeed a feasible solution to the original problem. This analysis used a constant gravity field. The second area applied a successive solution process to formulate a second order cone program that designs rendezvous and proximity operations trajectories.3, 4 These trajectories included a Newtonian gravity model. The equivalence of the solutions between the relaxed and the original problem is theoretically established. The proposed solution for designing the asteroid powered descent trajectory is to use convex optimization, a gravity model with higher fidelity than Newtonian, and an iterative solution process to design the fuel optimal trajectory. The solution to the convex optimization problem is the thrust profile, magnitude and direction, that will yield the minimum fuel trajectory for a soft landing at the target site, subject to various mission and operational constraints. The equations of motion are formulated in a rotating coordinate system and includes a high fidelity gravity model. The vehicle's thrust magnitude can vary between maximum and minimum bounds during the burn. Also, constraints are included to ensure that the vehicle does not run out of propellant, or go below the asteroid's surface, and any vehicle pointing requirements. The equations of motion are discretized and propagated with the trapezoidal rule in order to produce equality constraints for the optimization problem. These equality constraints allow the optimization algorithm to solve the entire problem, without including a propagator inside the optimization algorithm.

A Segment-Based Trajectory Similarity Measure in the Urban Transportation Systems.

PubMed

Mao, Yingchi; Zhong, Haishi; Xiao, Xianjian; Li, Xiaofang

2017-03-06

With the rapid spread of built-in GPS handheld smart devices, the trajectory data from GPS sensors has grown explosively. Trajectory data has spatio-temporal characteristics and rich information. Using trajectory data processing techniques can mine the patterns of human activities and the moving patterns of vehicles in the intelligent transportation systems. A trajectory similarity measure is one of the most important issues in trajectory data mining (clustering, classification, frequent pattern mining, etc.). Unfortunately, the main similarity measure algorithms with the trajectory data have been found to be inaccurate, highly sensitive of sampling methods, and have low robustness for the noise data. To solve the above problems, three distances and their corresponding computation methods are proposed in this paper. The point-segment distance can decrease the sensitivity of the point sampling methods. The prediction distance optimizes the temporal distance with the features of trajectory data. The segment-segment distance introduces the trajectory shape factor into the similarity measurement to improve the accuracy. The three kinds of distance are integrated with the traditional dynamic time warping algorithm (DTW) algorithm to propose a new segment-based dynamic time warping algorithm (SDTW). The experimental results show that the SDTW algorithm can exhibit about 57%, 86%, and 31% better accuracy than the longest common subsequence algorithm (LCSS), and edit distance on real sequence algorithm (EDR) , and DTW, respectively, and that the sensitivity to the noise data is lower than that those algorithms.

The Detection of Transport Land-Use Data Using Crowdsourcing Taxi Trajectory

NASA Astrophysics Data System (ADS)

Ai, T.; Yang, W.

2016-06-01

This study tries to explore the question of transport land-use change detection by large volume of vehicle trajectory data, presenting a method based on Deluanay triangulation. The whole method includes three steps. The first one is to pre-process the vehicle trajectory data including the point anomaly removing and the conversion of trajectory point to track line. Secondly, construct Deluanay triangulation within the vehicle trajectory line to detect neighborhood relation. Considering the case that some of the trajectory segments are too long, we use a interpolation measure to add more points for the improved triangulation. Thirdly, extract the transport road by cutting short triangle edge and organizing the polygon topology. We have conducted the experiment of transport land-use change discovery using the data of taxi track in Beijing City. We extract not only the transport land-use area but also the semantic information such as the transformation speed, the traffic jam distribution, the main vehicle movement direction and others. Compared with the existed transport network data, such as OpenStreet Map, our method is proved to be quick and accurate.

Revealing nonergodic dynamics in living cells from a single particle trajectory

NASA Astrophysics Data System (ADS)

Lanoiselée, Yann; Grebenkov, Denis S.

2016-05-01

We propose the improved ergodicity and mixing estimators to identify nonergodic dynamics from a single particle trajectory. The estimators are based on the time-averaged characteristic function of the increments and can thus capture additional information on the process as compared to the conventional time-averaged mean-square displacement. The estimators are first investigated and validated for several models of anomalous diffusion, such as ergodic fractional Brownian motion and diffusion on percolating clusters, and nonergodic continuous-time random walks and scaled Brownian motion. The estimators are then applied to two sets of earlier published trajectories of mRNA molecules inside live Escherichia coli cells and of Kv2.1 potassium channels in the plasma membrane. These statistical tests did not reveal nonergodic features in the former set, while some trajectories of the latter set could be classified as nonergodic. Time averages along such trajectories are thus not representative and may be strongly misleading. Since the estimators do not rely on ensemble averages, the nonergodic features can be revealed separately for each trajectory, providing a more flexible and reliable analysis of single-particle tracking experiments in microbiology.

Calculation of trajectories and the rate of growth of curvilinear fatigue cracks in isotropic and composite plates

NASA Astrophysics Data System (ADS)

Pokhmurska, H.; Maksymovych, O.; Dzyubyk, A.; Dzyubyk, L.

2018-06-01

The methods of calculating the trajectories and the rate of growth of curvilinear fatigue cracks in isotropic and composite plate structure elements during cyclic loading along straight or curvilinear trajectories are developed. For isotropic and anisotropic materials, the methodes are developed on the basis of the force criterion of destruction with the additional application of the fatigue fracture diagrams. To find the change in the shape of the cracks in the loading process, the step-by-step method was used. At each stage, the direction of the growth of all vertices of cracks and the lengths of their arcs was found on the basis of determining the intensity coefficients of stresses by the method of singular integral equations. The results of calculations of the cracks system growth process are presented.

Longer-term Stream Nitrogen Dynamics after Wildfire and Salvage Harvesting: Implications for Management Concepts based on Trajectories of Post-disturbance Watershed Recovery.

NASA Astrophysics Data System (ADS)

Silins, U.; Emelko, M. B.; Bladon, K. D.; Stone, M.; Williams, C.; Martens, A. M.; Wagner, M. J.

2015-12-01

Biogeochemical processes reflecting interaction of vegetation and hydrology govern long-term export of nutrients such as nitrogen, phosphorus, and carbon over successional time scales. While management concepts of watershed "recovery" from disturbance back towards pre-disturbance conditions are often considered over much shorter timescales, few studies have directly explored watershed biogeochemical responses to disturbance long enough to directly document the longer-term trajectory of responses to severe land disturbance on nitrogen export. The objectives of this study were to document both the initial magnitude and patterns of longer-term recovery of stream nitrogen after the 2003 Lost Creek wildfire over nine years in front ranges of the Rocky Mountains in south-west Alberta, Canada. The study was conducted in seven instrumented catchments (4-14 km2), including burned, burned and salvage logged, and unburned (reference) conditions since 2004. Total nitrogen (TN) and nitrate (NO3-) concentrations and area-normalized yields were greater and more variable in burned and post-fire salvage logged catchments when compared with unburned catchments. Large initial increases in stream TN and NO3- production 1-3 years after both wildfire and post-fire salvage logging declined strongly to levels similar to, or below that of unburned watersheds 4-6 years after the fire, and continued to decline (although more slowly) 7-9 years after the wildfire. Post-fire salvage logging produced lower impacts on TN and NO3- in streams and these effects declined even more rapidly compared to the effects of wildfire alone. These changes closely corresponded to the early trajectory of establishment and rapid juvenile growth of post-fire regenerating forest vegetation in both catchment groups. While the concept of hydrologic recovery from disturbance is both a practical and meaningful concept for integrated landscape management for protection of forest water resources, the benchmark for "recovery" based on present conditions in undisturbed forests may vary widely depending on forest age and successional status.

Developmental Trajectories of Executive and Verbal Processes in Children with Phenylketonuria.

PubMed

Hawks, Zoë W; Strube, Michael J; Johnson, Neco X; Grange, Dorothy K; White, Desirée A

2018-01-01

Phenylketonuria (PKU) is a hereditary disorder characterized by disrupted phenylalanine metabolism and cognitive impairment. However, the precise nature and developmental trajectory of this cognitive impairment remains unclear. The present study used a verbal fluency task to dissociate executive and verbal processes in children with PKU (n = 23; 7-18 years) and controls (n = 44; 7-19 years). Data were collected at three longitudinal timepoints over a three-year period, and the contributions of age, group, and their interaction to fluency performance were evaluated. Results indicated impairments in executive processes in children with PKU, which were exacerbated by declining metabolic control.

Objective Ratings of Relationship Skills across Multiple Domains as Predictors of Marital Satisfaction Trajectories

PubMed Central

Lawrence, Erika; Pederson, Ashley; Bunde, Mali; Barry, Robin A.; Brock, Rebecca L.; Fazio, Emily; Mulryan, Lorin; Hunt, Sara; Madsen, Lisa; Dzankovic, Sandra

2008-01-01

Expanding upon social-learning and vulnerability-stress-adaptation approaches to marriage, the impact of multiple dyadic behaviors on marital satisfaction trajectories was examined in 101 couples. Semi-structured interviews were administered separately to husbands and wives at 3 months of marriage. Interviewers generated objective ratings for five domains: emotional closeness/intimacy, sexual intimacy/sensuality, interspousal support, decision-making/relational control, and communication/conflict management. Marital satisfaction was assessed four times over three years. Dyadic behaviors were associated with initial levels and rates of change in satisfaction, demonstrating the unique contributions of each relational skill on marital development. For husbands, sexual intimacy was the strongest predictor of change whereas for wives, communication/conflict management was the strongest predictor of change compared to other domains. Theoretical, methodological and clinical implications are discussed. PMID:19122752

Occupational Trajectories and Immigrant Worker Health

PubMed Central

Crollard, Allison; de Castro, A. B.; Tsai, Jenny Hsin-Chun

2013-01-01

During their initial years in the receiving country, many immigrants experience occupational downgrading. Downgrading is a loss of occupational status between one’s last job in the home country and first job in the receiving country, often resulting in overeducation or overqualification. Although the extent and determinants of such occupational trajectories have been characterized, the connection to immigrant worker health has not been widely examined. However, an emerging body of knowledge indicates that negative health outcomes are associated with overeducation and overqualification in general worker populations, suggesting similar experiences by immigrant workers. This article provides an overview of the magnitude and conceptualization of occupational downgrading, overeducation, and overqualification and discusses implications for immigrant worker health. Occupational health professionals should spearhead research efforts on occupational downgrading, raise public awareness about the issue, and serve as advocates for immigrant workers’ rights. PMID:23092177

Patterns and Predictors of Growth in Divorced Fathers' Health Status and Substance Use

PubMed Central

DeGarmo, David S.; Reid, John B.; Leve, Leslie D.; Chamberlain, Patricia; Knutson, John F.

2009-01-01

Health status and substance use trajectories are described over 18 months for a county sample of 230 divorced fathers of young children aged 4 to 11. One third of the sample was clinically depressed. Health problems, drinking, and hard drug use were stable over time for the sample, whereas depression, smoking, and marijuana use exhibited overall mean reductions. Variance components revealed significant individual differences in average levels and trajectories for health and substance use outcomes. Controlling for fathers' antisociality, negative life events, and social support, fathering identity predicted reductions in health-related problems and marijuana use. Father involvement reduced drinking and marijuana use. Antisociality was the strongest risk factor for health and substance use outcomes. Implications for application of a generative fathering perspective in practice and preventive interventions are discussed. PMID:19477763

Targeting Oxidative Stress and Aberrant Critical Period Plasticity in the Developmental Trajectory to Schizophrenia

PubMed Central

Do, Kim Q.; Cuenod, Michel; Hensch, Takao K.

2015-01-01

Schizophrenia is a neurodevelopmental disorder reflecting a convergence of genetic risk and early life stress. The slow progression to first psychotic episode represents both a window of vulnerability as well as opportunity for therapeutic intervention. Here, we consider recent neurobiological insight into the cellular and molecular components of developmental critical periods and their vulnerability to redox dysregulation. In particular, the consistent loss of parvalbumin-positive interneuron (PVI) function and their surrounding perineuronal nets (PNNs) as well as myelination in patient brains is consistent with a delayed or extended period of circuit instability. This linkage to critical period triggers (PVI) and brakes (PNN, myelin) implicates mistimed trajectories of brain development in mental illness. Strategically introduced antioxidant treatment or later reinforcement of molecular brakes may then offer a novel prophylactic psychiatry. PMID:26032508

Parenting and Trajectories of Children’s Maladaptive Behaviors: A 12-year Prospective Community Study

PubMed Central

Luyckx, Koen; Tildesley, Elizabeth A.; Soenens, Bart; Andrews, Judy A.; Hampson, Sarah E.; Peterson, Missy; Duriez, Bart

2011-01-01

This study investigated how parenting accounted for inter-individual differences in developmental trajectories of different child behaviors across childhood and adolescence. In a cohort sequential community sample of 1,049 children, latent class growth analysis was applied to three parent-reported dimensions (monitoring, positive parenting, inconsistent discipline) across 12 annual assessments (ages 6–18). Four longitudinal parenting styles (authoritative, authoritarian, indulgent, uninvolved) were differentiated on the basis of levels and rates of change in the constituent parenting dimensions. Multi-group analyses demonstrated that these parenting styles were differentially related to changes in parent- and child-reported measures of children’s alcohol and cigarette use, antisocial behavior, and internalizing symptoms, with the authoritative parenting class being related to the most optimal long-term development. Practical implications and future research suggestions are discussed. PMID:21534057

Short- and Mid-Term Effects of Violent Victimization on Delinquency: A Multilevel Growth-Curve Modeling Approach.

PubMed

Kim, Young S; Lo, Celia C

2016-10-01

The present study investigates how adolescents' experiences of violent victimization exert short- and mid-term effects on their involvement in delinquency. The study compares and contrasts delinquency trajectories of youths whose experiences of violent victimization differ. A multilevel growth-curve modeling approach is applied to analyze data from five waves of the National Youth Survey. The results show that, although delinquency involvement increases as youths experience violent victimization, delinquency trajectories differ with the type of violent victimization, specifically, parental versus non-parental victimization. Violent victimization by parents produced a sharp initial decline in delinquency (short-term effect) followed by a rapid acceleration (mid-term effect). In turn, non-parental violence showed a stable trend over time. The findings have important implications for prevention and treatment services. © The Author(s) 2015.

Developmental Course of Impulsivity and Capability from Age 10 to Age 25 as Related to Trajectory of Suicide Attempt in a Community Cohort

PubMed Central

Kasen, Stephanie; Cohen, Patricia; Chen, Henian

2011-01-01

Hierarchical linear models were used to examine trajectories of impulsivity and capability between ages 10 and 25 in relation to suicide attempt in 770 youths followed longitudinally: intercepts were set at age 17. The impulsivity measure assessed features of urgency (e.g., poor control, quick provocation, and disregard for external constraints); the capability measure assessed aspects of self-esteem and mastery. Compared to nonattempters, attempters reported significantly higher impulsivity levels with less age-related decline, and significantly lower capability levels with less age-related increase. Independent of other risks, suicide attempt was related significantly to higher impulsivity between ages 10 and 25, especially during the younger years, and lower capability. Implications of those findings for further suicidal behavior and preventive/intervention efforts are discussed. PMID:21342218

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

PubMed

Thoresen, Carl J; Bradley, Jill C; Bliese, Paul D; Thoresen, Joseph D

2004-10-01

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. (c) 2004 APA, all rights reserved

Typologies of family functioning and children's adjustment during the early school years.

PubMed

Sturge-Apple, Melissa L; Davies, Patrick T; Cummings, E Mark

2010-01-01

Guided by family systems theory, the present study sought to identify patterns of family functioning from observational assessments of interparental, parent-child, and triadic contexts. In addition, it charted the implications for patterns of family functioning for children's developmental trajectories of adjustment in the school context across the early school years. Two-hundred thirty-four kindergarten children (129 girls and 105 boys; mean age = 6.0 years, SD = 0.50 at Wave 1) and their parents participated in this multimethod, 3-year longitudinal investigation. As expected, latent class analyses extracted 3 primary typologies of functioning including: (a) cohesive, (b) enmeshed, and (c) disengaged families. Furthermore, family patterns were differentially associated with children's maladaptive adjustment trajectories in the school context. The findings highlight the developmental utility of incorporating pattern-based approaches to family functioning.

Trajectories in Physical Activity and Sedentary Time Among Women Veterans in the Women’s Health Initiative

PubMed Central

Washington, Donna L.; Gray, Kristen; Hoerster, Katherine D.; Katon, Jodie G.; Cochrane, Barbara B.; LaMonte, Michael J.; Weitlauf, Julie C.; Groessl, Erik; Bastian, Lori; Vitolins, Mara Z.; Tinker, Lesley

2016-01-01

Abstract Purpose of the Study: Trajectories of physical activity (PA) and sedentary time (ST) after military separation are likely important determinants of women’s health outcomes later in life, because low PA and high ST are known contributors to premature mortality risk. Our objective was to compare longitudinal trajectories of recreational PA and ST between Veteran and non-Veteran postmenopausal women from the Women’s Health Initiative (WHI). Design and Methods: Women Veteran ( n = 3,719) and non-Veteran ( n = 141,800) WHI participants were included. Self-reported participation in recreational PA, converted to metabolic equivalent (MET)-hours/week, was prospectively assessed over 8 years. Self-reported ST, defined as hours/day sitting or lying down, was collected at baseline and at Years 3 and 6. Generalized estimating equations were used to compare trajectories of PA and ST between Veterans and non-Veterans, adjusted for demographics and lifestyle behaviors. Results: Veterans had higher baseline PA than non-Veterans (13.2 vs 12.5 MET-hours/week, p = .03). PA declined for both groups, with a steeper decline among Veterans (change/visit year −0.19 vs −0.02 MET-hours/week; interaction p < .001). At baseline, Veterans and non-Veterans had similar levels of ST (107.2 vs 105.9 hours/week, p = 0.42). Over time, ST remained stable among Veterans but declined slightly among non-Veterans (change/visit year −0.19 vs −0.49 hours/week; interaction p = .01). Implications: The less favorable longitudinal trajectories of PA and ST we observed for women Veterans may contribute to worse health among these individuals later in life. Understanding barriers to enhancing PA and reducing ST in women Veterans could lead to more effective approaches to intervening on these health behaviors. PMID:26768390

[Suicide among the French National Police forces: Implication of life events and life trajectories].

PubMed

Encrenaz, G; Miras, A; Contrand, B; Séguin, M; Moulki, M; Queinec, R; René, J-S; Fériot, A; Mougin, M; Bonfils, M; Marien, P; Michel, G; Lagarde, E

2016-08-01

Research indicates that suicide rates are high among members of law enforcement. Our objectives were: (1) to determine life events implicated in suicide mortality among French law enforcement; and (2) to describe the different life trajectories of police officers who deceased by suicide. All suicides of police officers which occurred during 2008 (n=49) were explored using the psychological autopsy method. Key informants were: a supervisor, a colleague and a member of the family or a close friend. Each of them were interviewed by trained psychologists using standardized questionnaires exploring: sociodemographic characteristics, life events, social integration and support, health service use, mental health with the Composite International Diagnostic Interview short form (CIDI-SF), occupational stress with the Spielberger Inventory, impulsiveness with the Barratt Impulsiveness Scale and aggressiveness with the Brown-Goodwin Lifetime Aggression Scale. Information was then summarized in a timetable life trajectory of all life areas. All cases were finally appraised by at least two experts in order to identify the determinants of the suicide and to determine psychiatric diagnoses. For each period of time, a burdensomeness score was determined, from 6 (no adversity) to 1 (adversities in each sphere of life). Of the 49 cases of suicide, two were excluded and 39 were investigated and appraised (response rate: 39/47=83%). Eighty-two percent of the suicide cases were men and the mean age at death was 35years. In more than half of the cases, police officers used their service weapon to commit suicide. All deceased police officers were suffering from mental health symptoms (primarily depression). Of them, two thirds had used healthcare for this distress. The main other cause of suicide was problems in the married life (70% of the cases). Four distinct types of life trajectories of adversities could be identified by a qualitative analysis. It is the first time such a study was performed in France, and results are concordant with those of the literature. This study showed that all deceased police officers were suffering from mental disorders and that there was not one single profile of life trajectory: screening and support of police officers in distress need to be prioritized. Moreover, results suggested that the availability of the service weapon during off-duty periods should be reconsidered. This study helped the Home ministry to elaborate and improve strategies to prevent suicide among police officers. Copyright © 2015 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

Deep Processing Strategies and Critical Thinking: Developmental Trajectories Using Latent Growth Analyses

ERIC Educational Resources Information Center

Phan, Huy P.

2011-01-01

The author explored the developmental courses of deep learning approach and critical thinking over a 2-year period. Latent growth curve modeling (LGM) procedures were used to test and trace the trajectories of both theoretical frameworks over time. Participants were 264 (119 women, 145 men) university undergraduates. The Deep Learning subscale of…

Comparing Classical Water Models Using Molecular Dynamics to Find Bulk Properties

ERIC Educational Resources Information Center

Kinnaman, Laura J.; Roller, Rachel M.; Miller, Carrie S.

2018-01-01

A computational chemistry exercise for the undergraduate physical chemistry laboratory is described. In this exercise, students use the molecular dynamics package Amber to generate trajectories of bulk liquid water for 4 different water models (TIP3P, OPC, SPC/E, and TIP4Pew). Students then process the trajectory to calculate structural (radial…

Changing Youth? Continuities and Ruptures in Transitions into Adulthood among Catalan Young People

ERIC Educational Resources Information Center

Serracant, Pau

2012-01-01

The globalisation process has an impact at the micro-level on life-course patterns: concretely, the trajectories of young people into adulthood are being sharply modified. At a European level, the extension, de-linearisation, reversibility and diversification of youth trajectories have been identified as major changes. However, the extent to which…

From On-Campus to Online: A Trajectory of Innovation, Internationalization and Inclusion

ERIC Educational Resources Information Center

Moreira, Darlinda

2016-01-01

This paper presents a study focused on a trajectory for developing an online operating mode on a campus-based university in the area of Massachusetts, USA. It addresses the innovation process and the changes and challenges faced by faculty and administrators. Methodologically-speaking, a mainly ethnographic approach was used for a systematic…

Modelling Transformations of Quadratic Functions: A Proposal of Inductive Inquiry

ERIC Educational Resources Information Center

Sokolowski, Andrzej

2013-01-01

This paper presents a study about using scientific simulations to enhance the process of mathematical modelling. The main component of the study is a lesson whose major objective is to have students mathematise a trajectory of a projected object and then apply the model to formulate other trajectories by using the properties of function…

The National Trajectory Project of Individuals Found Not Criminally Responsible on Account of Mental Disorder in Canada. Part 3: Trajectories and Outcomes Through the Forensic System

PubMed Central

Crocker, Anne G; Charette, Yanick; Seto, Michael C; Nicholls, Tonia L; Côté, Gilles; Caulet, Malijai

2015-01-01

Objective: To examine the processing and Review Board (RB) disposition outcomes of people found not criminally responsible on account of mental disorder (NCRMD) across the 3 most populous provinces in Canada. Although the Criminal Code is federally legislated, criminal justice is administered by provinces and territories. It follows that a person with mental illness who comes into conflict with the law and subsequently comes under the management of a legally mandated RB may experience different trajectories across jurisdictions. Method: The National Trajectory Project examined 1800 men and women found NCRMD in British Columbia (n = 222), Quebec (n = 1094), and Ontario (n = 484) between May 2000 and April 2005, followed until December 2008. Results: We found significant interprovincial differences in the trajectories of people found NCRMD, including time detained in hospital and time under the supervision of an RB. The odds of being conditionally or absolutely discharged by the RB varied across provinces, even after number of past offences, diagnosis at verdict, and most severe index offence (all covariates decreased likelihood of discharge) were considered. Conclusions: Considerable discrepancies in the application of NCRMD legislation and the processing of NCRMD cases through the forensic system across the provinces suggests that fair and equitable treatment under the law could be enhanced by increased national integration and collaboration. PMID:25886687

Ares-I-X Vehicle Preliminary Range Safety Malfunction Turn Analysis

NASA Technical Reports Server (NTRS)

Beaty, James R.; Starr, Brett R.; Gowan, John W., Jr.

2008-01-01

Ares-I-X is the designation given to the flight test version of the Ares-I rocket (also known as the Crew Launch Vehicle - CLV) being developed by NASA. As part of the preliminary flight plan approval process for the test vehicle, a range safety malfunction turn analysis was performed to support the launch area risk assessment and vehicle destruct criteria development processes. Several vehicle failure scenarios were identified which could cause the vehicle trajectory to deviate from its normal flight path, and the effects of these failures were evaluated with an Ares-I-X 6 degrees-of-freedom (6-DOF) digital simulation, using the Program to Optimize Simulated Trajectories Version 2 (POST2) simulation framework. The Ares-I-X simulation analysis provides output files containing vehicle state information, which are used by other risk assessment and vehicle debris trajectory simulation tools to determine the risk to personnel and facilities in the vicinity of the launch area at Kennedy Space Center (KSC), and to develop the vehicle destruct criteria used by the flight test range safety officer. The simulation analysis approach used for this study is described, including descriptions of the failure modes which were considered and the underlying assumptions and ground rules of the study, and preliminary results are presented, determined by analysis of the trajectory deviation of the failure cases, compared with the expected vehicle trajectory.

On the assumptions underlying milestoning.

PubMed

Vanden-Eijnden, Eric; Venturoli, Maddalena; Ciccotti, Giovanni; Elber, Ron

2008-11-07

Milestoning is a procedure to compute the time evolution of complicated processes such as barrier crossing events or long diffusive transitions between predefined states. Milestoning reduces the dynamics to transition events between intermediates (the milestones) and computes the local kinetic information to describe these transitions via short molecular dynamics (MD) runs between the milestones. The procedure relies on the ability to reinitialize MD trajectories on the milestones to get the right kinetic information about the transitions. It also rests on the assumptions that the transition events between successive milestones and the time lags between these transitions are statistically independent. In this paper, we analyze the validity of these assumptions. We show that sets of optimal milestones exist, i.e., sets such that successive transitions are indeed statistically independent. The proof of this claim relies on the results of transition path theory and uses the isocommittor surfaces of the reaction as milestones. For systems in the overdamped limit, we also obtain the probability distribution to reinitialize the MD trajectories on the milestones, and we discuss why this distribution is not available in closed form for systems with inertia. We explain why the time lags between transitions are not statistically independent even for optimal milestones, but we show that working with such milestones allows one to compute mean first passage times between milestones exactly. Finally, we discuss some practical implications of our results and we compare milestoning with Markov state models in view of our findings.

Healthy eating decisions require efficient dietary self-control in children: A mouse-tracking food decision study.

PubMed

Ha, Oh-Ryeong; Bruce, Amanda S; Pruitt, Stephen W; Cherry, J Bradley C; Smith, T Ryan; Burkart, Dominic; Bruce, Jared M; Lim, Seung-Lark

2016-10-01

Learning how to make healthy eating decisions, (i.e., resisting unhealthy foods and consuming healthy foods), enhances physical development and reduces health risks in children. Although healthy eating decisions are known to be challenging for children, the mechanisms of children's food choice processes are not fully understood. The present study recorded mouse movement trajectories while eighteen children aged 8-13 years were choosing between eating and rejecting foods. Children were inclined to choose to eat rather than to reject foods, and preferred unhealthy foods over healthy foods, implying that rejecting unhealthy foods could be a demanding choice. When children rejected unhealthy foods, mouse trajectories were characterized by large curvature toward an eating choice in the beginning, late decision shifting time toward a rejecting choice, and slowed response times. These results suggested that children exercised greater cognitive efforts with longer decision times to resist unhealthy foods, providing evidence that children require dietary self-control to make healthy eating-decisions by resisting the temptation of unhealthy foods. Developmentally, older children attempted to exercise greater cognitive efforts for consuming healthy foods than younger children, suggesting that development of dietary self-control contributes to healthy eating-decisions. The study also documents that healthy weight children with higher BMIs were more likely to choose to reject healthy foods. Overall, findings have important implications for how children make healthy eating choices and the role of dietary self-control in eating decisions. Published by Elsevier Ltd.

Strategy of arm movement control is determined by minimization of neural effort for joint coordination.

PubMed

Dounskaia, Natalia; Shimansky, Yury

2016-06-01

Optimality criteria underlying organization of arm movements are often validated by testing their ability to adequately predict hand trajectories. However, kinematic redundancy of the arm allows production of the same hand trajectory through different joint coordination patterns. We therefore consider movement optimality at the level of joint coordination patterns. A review of studies of multi-joint movement control suggests that a 'trailing' pattern of joint control is consistently observed during which a single ('leading') joint is rotated actively and interaction torque produced by this joint is the primary contributor to the motion of the other ('trailing') joints. A tendency to use the trailing pattern whenever the kinematic redundancy is sufficient and increased utilization of this pattern during skillful movements suggests optimality of the trailing pattern. The goal of this study is to determine the cost function minimization of which predicts the trailing pattern. We show that extensive experimental testing of many known cost functions cannot successfully explain optimality of the trailing pattern. We therefore propose a novel cost function that represents neural effort for joint coordination. That effort is quantified as the cost of neural information processing required for joint coordination. We show that a tendency to reduce this 'neurocomputational' cost predicts the trailing pattern and that the theoretically developed predictions fully agree with the experimental findings on control of multi-joint movements. Implications for future research of the suggested interpretation of the trailing joint control pattern and the theory of joint coordination underlying it are discussed.

Negotiated dying: a grounded theory of how nurses shape withdrawal of treatment in hospital critical care units.

PubMed

Long-Sutehall, Tracy; Willis, Helen; Palmer, Rachel; Ugboma, Debra; Addington-Hall, Julia; Coombs, Maureen

2011-12-01

The process of withdrawal of treatment in critical care environments has created ethical and moral dilemmas in relation to end of life care in the UK and elsewhere. Common within this discourse is the differing demands made on health professionals as they strive to provide care for the dying patient and family members. Despite reports that withdrawal of treatment is a source of tension between those nurses and doctors involved in the process, the role of the nurse in facilitating withdrawal of treatment has received relatively little attention. To illustrate how differing dying trajectories impact on decision-making underpinning withdrawal of treatment processes, and what nurses do to shape withdrawal of treatment. Qualitative methods of enquiry using clinical vignettes and applying Charmaz's grounded theory method. Single audio-recorded qualitative interviews with thirteen critical care nurses from four intensive care specialities: cardiac; general; neurological and renal were carried out. Interviews were facilitated by an end-of-life vignette developed with clinical collaborators. Across critical care areas four key dying trajectories were identified. These trajectories were shaped by contested boundaries associated with delayed or stalled decision-making around how withdrawal of treatment should proceed. Nurses provided end of life care (including collaborative and action-oriented skills) to shape the dying trajectory of patients so as to satisfy the wishes of the patient and family, and their own professional aims. Differing views as to when withdrawal of treatment should commence and how it should be operationalised appeared to be underpinned by the requirements of the role that health professionals fulfil, with doctors focusing on making withdrawal of treatment decisions, and nurse's being tasked with operationalising the processes that constitute it. Multidisciplinary teams need a 'shared' understanding of each other's roles, responsibilities, aims, and motivations when planning and implementing the dying trajectory of withdrawal of treatment. 2011 Elsevier Ltd. All rights reserved.

Calculation of water drop trajectories to and about arbitrary three-dimensional lifting and nonlifting bodies in potential airflow

NASA Technical Reports Server (NTRS)

Norment, H. G.

1985-01-01

Subsonic, external flow about nonlifting bodies, lifting bodies or combinations of lifting and nonlifting bodies is calculated by a modified version of the Hess lifting code. Trajectory calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Inlet flow can be accommodated, and high Mach number compressibility effects are corrected for approximately. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

Continuous measurement of two spatially separated superconducting qubits: quantum trajectories and statistics

NASA Astrophysics Data System (ADS)

Roch, Nicolas

2015-03-01

Measurement can be harnessed to probabilistically generate entanglement in the absence of local interactions, for example between spatially separated quantum objects. Continuous weak measurement allows us to observe the dynamics associated with this process. In particular, we perform joint dispersive readout of two superconducting transmon qubits separated by one meter of coaxial cable. We track the evolution of a joint quantum state under the influence of measurement, both as an ensemble and as a set of individual quantum trajectories. Analyzing the statistics of such quantum trajectories can shed new light on the underlying entangling mechanism.

Failure detection in high-performance clusters and computers using chaotic map computations

DOEpatents

Rao, Nageswara S.

2015-09-01

A programmable media includes a processing unit capable of independent operation in a machine that is capable of executing 10.sup.18 floating point operations per second. The processing unit is in communication with a memory element and an interconnect that couples computing nodes. The programmable media includes a logical unit configured to execute arithmetic functions, comparative functions, and/or logical functions. The processing unit is configured to detect computing component failures, memory element failures and/or interconnect failures by executing programming threads that generate one or more chaotic map trajectories. The central processing unit or graphical processing unit is configured to detect a computing component failure, memory element failure and/or an interconnect failure through an automated comparison of signal trajectories generated by the chaotic maps.

Power spectral density of a single Brownian trajectory: what one can and cannot learn from it

NASA Astrophysics Data System (ADS)

Krapf, Diego; Marinari, Enzo; Metzler, Ralf; Oshanin, Gleb; Xu, Xinran; Squarcini, Alessio

2018-02-01

The power spectral density (PSD) of any time-dependent stochastic process X t is a meaningful feature of its spectral content. In its text-book definition, the PSD is the Fourier transform of the covariance function of X t over an infinitely large observation time T, that is, it is defined as an ensemble-averaged property taken in the limit T\\to ∞ . A legitimate question is what information on the PSD can be reliably obtained from single-trajectory experiments, if one goes beyond the standard definition and analyzes the PSD of a single trajectory recorded for a finite observation time T. In quest for this answer, for a d-dimensional Brownian motion (BM) we calculate the probability density function of a single-trajectory PSD for arbitrary frequency f, finite observation time T and arbitrary number k of projections of the trajectory on different axes. We show analytically that the scaling exponent for the frequency-dependence of the PSD specific to an ensemble of BM trajectories can be already obtained from a single trajectory, while the numerical amplitude in the relation between the ensemble-averaged and single-trajectory PSDs is a fluctuating property which varies from realization to realization. The distribution of this amplitude is calculated exactly and is discussed in detail. Our results are confirmed by numerical simulations and single-particle tracking experiments, with remarkably good agreement. In addition we consider a truncated Wiener representation of BM, and the case of a discrete-time lattice random walk. We highlight some differences in the behavior of a single-trajectory PSD for BM and for the two latter situations. The framework developed herein will allow for meaningful physical analysis of experimental stochastic trajectories.

Integrated use of spatial and semantic relationships for extracting road networks from floating car data

NASA Astrophysics Data System (ADS)

Li, Jun; Qin, Qiming; Xie, Chao; Zhao, Yue

2012-10-01

The update frequency of digital road maps influences the quality of road-dependent services. However, digital road maps surveyed by probe vehicles or extracted from remotely sensed images still have a long updating circle and their cost remain high. With GPS technology and wireless communication technology maturing and their cost decreasing, floating car technology has been used in traffic monitoring and management, and the dynamic positioning data from floating cars become a new data source for updating road maps. In this paper, we aim to update digital road maps using the floating car data from China's National Commercial Vehicle Monitoring Platform, and present an incremental road network extraction method suitable for the platform's GPS data whose sampling frequency is low and which cover a large area. Based on both spatial and semantic relationships between a trajectory point and its associated road segment, the method classifies each trajectory point, and then merges every trajectory point into the candidate road network through the adding or modifying process according to its type. The road network is gradually updated until all trajectories have been processed. Finally, this method is applied in the updating process of major roads in North China and the experimental results reveal that it can accurately derive geometric information of roads under various scenes. This paper provides a highly-efficient, low-cost approach to update digital road maps.

Racializing drug design: implications of pharmacogenomics for health disparities.

PubMed

Lee, Sandra Soo-Jin

2005-12-01

Current practices of using "race" in pharmacogenomics research demands consideration of the ethical and social implications for understandings of group difference and for efforts to eliminate health disparities. This discussion focuses on an "infrastructure of racialization" created by current trajectories of research on genetic differences among racially identified groups, the use of race as a proxy for risk in clinical practice, and increasing interest in new market niches by the pharmaceutical industry. The confluence of these factors has resulted in the conflation of genes, disease, and race. I argue that public investment in pharmacogenomics requires careful consideration of current inequities in health status and social and ethical concerns over reifying race and issues of distributive justice.

Trajectory-based nonadiabatic dynamics with time-dependent density functional theory.

PubMed

Curchod, Basile F E; Rothlisberger, Ursula; Tavernelli, Ivano

2013-05-10

Understanding the fate of an electronically excited molecule constitutes an important task for theoretical chemistry, and practical implications range from the interpretation of atto- and femtosecond spectroscopy to the development of light-driven molecular machines, the control of photochemical reactions, and the possibility of capturing sunlight energy. However, many challenging conceptual and technical problems are involved in the description of these phenomena such as 1) the failure of the well-known Born-Oppenheimer approximation; 2) the need for accurate electronic properties such as potential energy surfaces, excited nuclear forces, or nonadiabatic coupling terms; and 3) the necessity of describing the dynamics of the photoexcited nuclear wavepacket. This review provides an overview of the current methods to address points 1) and 3) and shows how time-dependent density functional theory (TDDFT) and its linear-response extension can be used for point 2). First, the derivation of Ehrenfest dynamics and nonadiabatic Bohmian dynamics is discussed and linked to Tully's trajectory surface hopping. Second, the coupling of these trajectory-based nonadiabatic schemes with TDDFT is described in detail with special emphasis on the derivation of the required electronic structure properties. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Impact of convection on stratospheric humidity and upper tropospheric clouds

NASA Astrophysics Data System (ADS)

Ueyama, R.; Schoeberl, M. R.; Jensen, E. J.; Pfister, L.; Avery, M. A.

2017-12-01

The role of convection on stratospheric water vapor and upper tropospheric cloud fraction is investigated using two sets of complementary transport and microphysical models driven by MERRA-2 and ERA-Interim meteorological analyses: (1) computationally efficient ensembles of forward trajectories with simplified cloud microphysics, and (2) one-dimensional simulations with detailed microphysics along back trajectories. Convective influence along the trajectories is diagnosed based on TRMM/GPM rainfall products and geostationary infrared satellite cloud-top measurements, with convective cloud-top height adjusted to match the CloudSat, CALIPSO, and CATS measurements. We evaluate and constrain the model results by comparison with satellite observations (e.g., Aura MLS, CALIPSO CALIOP) and high-altitude aircraft campaigns (e.g., ATTREX, POSIDON). Convection moistens the lower stratosphere by approximately 10-15% and increases the cloud fraction in the upper troposphere by 35-50%. Convective moistening is dominated by the saturating effect of parcels; convectively-lofted ice has a negligible impact on lower stratospheric humidity. We also find that the highest convective clouds have a disproportionately large impact on stratospheric water vapor because stratospheric relative humidity is low. Implications of these model results on the role of convection on present and future climate will be discussed.

Systematic Review: A Reevaluation and Update of the Integrative (Trajectory) Model of Pediatric Medical Traumatic Stress.

PubMed

Price, Julia; Kassam-Adams, Nancy; Alderfer, Melissa A; Christofferson, Jennifer; Kazak, Anne E

2016-01-01

The objective of this systematic review is to reevaluate and update the Integrative Model of Pediatric Medical Traumatic Stress (PMTS; Kazak et al., 2006), which provides a conceptual framework for traumatic stress responses across pediatric illnesses and injuries. Using established systematic review guidelines, we searched PsycINFO, Cumulative Index to Nursing and Allied Health Literature, and PubMed (producing 216 PMTS papers published since 2005), extracted findings for review, and organized and interpreted findings within the Integrative Model framework. Recent PMTS research has included additional pediatric populations, used advanced longitudinal modeling techniques, clarified relations between parent and child PMTS, and considered effects of PMTS on health outcomes. Results support and extend the model's five assumptions, and suggest a sixth assumption related to health outcomes and PMTS. Based on new evidence, the renamed Integrative Trajectory Model includes phases corresponding with medical events, adds family-centered trajectories, reaffirms a competency-based framework, and suggests updated assessment and intervention implications. © The Author 2015. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Multivalued classical mechanics arising from singularity loops in complex time

NASA Astrophysics Data System (ADS)

Koch, Werner; Tannor, David J.

2018-02-01

Complex-valued classical trajectories in complex time encounter singular times at which the momentum diverges. A closed time contour around such a singular time may result in final values for q and p that differ from their initial values. In this work, we develop a calculus for determining the exponent and prefactor of the asymptotic time dependence of p from the singularities of the potential as the singularity time is approached. We identify this exponent with the number of singularity loops giving distinct solutions to Hamilton's equations of motion. The theory is illustrated for the Eckart, Coulomb, Morse, and quartic potentials. Collectively, these potentials illustrate a wide variety of situations: poles and essential singularities at finite and infinite coordinate values. We demonstrate quantitative agreement between analytical and numerical exponents and prefactors, as well as the connection between the exponent and the time circuit count. This work provides the theoretical underpinnings for the choice of time contours described in the studies of Doll et al. [J. Chem. Phys. 58(4), 1343-1351 (1973)] and Petersen and Kay [J. Chem. Phys. 141(5), 054114 (2014)]. It also has implications for wavepacket reconstruction from complex classical trajectories when multiple branches of trajectories are involved.

Trajectories of teacher-student warmth and conflict at the transition to middle school: Effects on academic engagement and achievement.

PubMed

Hughes, Jan N; Cao, Qian

2018-04-01

Using piece-wise longitudinal trajectory analysis, this study investigated trajectories of teacher-reported warmth and conflict in their relationships with students 4years prior to and 3years following the transition to middle school in a sample of 550 academically at-risk and ethnically diverse adolescents. At the transition to middle school, teacher reports of warmth showed a significant drop (shift in intercept), above age-related declines. Both warmth and conflict declined across the middle school years. Structural equation modeling (SEM) tested effects of the shifts in intercept and the post-transition slopes on reading and math achievement, teacher-rated engagement, and student-reported school belonging 3years post-transition, above pre-transition levels of the outcome. For warmth, a drop in intercept predicted lower math scores and engagement, and a more positive slope predicted higher engagement. For conflict, an increase in intercept and a negative slope predicted lower engagement. Implications of findings for reducing normative declines in academic engagement in middle school are discussed. Copyright © 2017 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

A study to evaluate STS heads-up ascent trajectory performance employing a minimum-Hamiltonian optimization strategy

NASA Technical Reports Server (NTRS)

Sinha, Sujit

1988-01-01

A study was conducted to evaluate the performance implications of a heads-up ascent flight design for the Space Transportation System, as compared to the current heads-down flight mode. The procedure involved the use of the Minimum Hamiltonian Ascent Shuttle Trajectory Evaluation Program, which is a three-degree-of-freedom moment balance simulation of shuttle ascent. A minimum-Hamiltonian optimization strategy was employed to maximize injection weight as a function of maximum dynamic pressure constraint and Solid Rocket Motor burnrate. Performance Reference Mission Four trajectory groundrules were used for consistency. The major conclusions are that for heads-up ascent and a mission nominal design maximum dynamic pressure value of 680 psf, the optimum solid motor burnrate is 0.394 ips, which produces a performance enhancement of 4293 lbm relative to the baseline heads-down ascent, with 0.368 ips burnrate solid motors and a 680 psf dynamic pressure constraint. However, no performance advantage exists for heads-up flight if the current Solid Rocket Motor target burnrate of 0.368 ips is used. The advantage of heads-up ascent flight employing the current burnrate is that Space Shuttle Main Engine throttling for dynamic pressure control is not necessary.

Predictors of Parenting Stress Trajectories in Premature Infant–Mother Dyads

PubMed Central

Spinelli, Maria; Poehlmann, Julie; Bolt, Daniel

2014-01-01

This prospective longitudinal study examined predictors of parenting stress trajectories over time in a sample of 125 mothers and their preterm infants. Infant (multiple birth, gestational age, days hospitalized, and neonatal health risks) and maternal (socioeconomic, education, depressive symptoms, social support, and quality of interaction during infant feeding) characteristics were collected just prior to infant hospital discharge. Parenting stress and maternal interaction quality during play were measured at 4, 24, and 36 months corrected age. Hierarchical linear modeling was used to analyze infant and maternal characteristics as predictors of parenting stress scores and change over time. Results indicated significant variability across individuals in parenting stress at 4 months and in change trajectories. Mothers of multiples and infants with more medical risks and shorter hospitalization, and mothers with lower education and more depressive symptoms, reported more parenting stress at 4 months of age. Parenting stress decreased over time for mothers of multiples and for mothers with lower education more than for mothers of singletons or for mothers with higher educational levels. Changes in parenting stress scores over time were negatively associated with maternal behaviors during mother–infant interactions. Results are interpreted for their implications for preventive interventions. PMID:24188086

Trajectory control of PbSe–γ-Fe2O3 nanoplatforms under viscous flow and an external magnetic field

PubMed Central

Etgar, Lioz; Nakhmani, Arie; Tannenbaum, Allen; Lifshitz, Efrat; Tannenbaum, Rina

2010-01-01

The flow behavior of nanostructure clusters, consisting of chemically bonded PbSe quantum dots and magnetic γ -Fe2O3 nanoparticles, has been investigated. The clusters are regarded as model nanoplatforms with multiple functionalities, where the γ -Fe2O3 magnets serve as transport vehicles, manipulated by an external magnetic field gradient, and the quantum dots act as fluorescence tags within an optical window in the near-infrared regime. The clusters’ flow was characterized by visualizing their trajectories within a viscous fluid (mimicking a blood stream), using an optical imaging method, while the trajectory pictures were analyzed by a specially developed processing package. The trajectories were examined under various flow rates, viscosities and applied magnetic field strengths. The results revealed a control of the trajectories even at low magnetic fields (<1 T), validating the use of similar nanoplatforms as active targeting constituents in personalized medicine. PMID:20368678

Drug trajectories among youth undergoing treatment: the influence of psychological problems and delinquency.

PubMed

Brunelle, Natacha; Bertrand, Karine; Beaudoin, Isabelle; Ledoux, Cinthia; Gendron, Annie; Arseneault, Catherine

2013-08-01

Previous research has documented associations of addiction with delinquency and psychological problems. However, few studies have evaluated their influence on adolescent's drug use trajectories. The current study aims to examine the influence of these factors on the recovery trajectories of 199 youths aged 15.6 years on average admitted to inpatient and outpatient addiction treatment centers, followed up three and six months later. Results indicate that youth who show higher severity of drug abuse exhibit greater improvement than youth with a lower severity of drug abuse at the onset of treatment. Although psychological problems were associated with baseline drug use, they did not influence drug use trajectory over time. Only delinquency influenced the recovery trajectories of these youth. Results suggest that a high level of delinquency can have a significant effect on the drug recovery process of adolescents and that interventions should attempt to reduce both drug use and delinquency. Copyright © 2013 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Rapid design and optimization of low-thrust rendezvous/interception trajectory for asteroid deflection missions

NASA Astrophysics Data System (ADS)

Li, Shuang; Zhu, Yongsheng; Wang, Yukai

2014-02-01

Asteroid deflection techniques are essential in order to protect the Earth from catastrophic impacts by hazardous asteroids. Rapid design and optimization of low-thrust rendezvous/interception trajectories is considered as one of the key technologies to successfully deflect potentially hazardous asteroids. In this paper, we address a general framework for the rapid design and optimization of low-thrust rendezvous/interception trajectories for future asteroid deflection missions. The design and optimization process includes three closely associated steps. Firstly, shape-based approaches and genetic algorithm (GA) are adopted to perform preliminary design, which provides a reasonable initial guess for subsequent accurate optimization. Secondly, Radau pseudospectral method is utilized to transcribe the low-thrust trajectory optimization problem into a discrete nonlinear programming (NLP) problem. Finally, sequential quadratic programming (SQP) is used to efficiently solve the nonlinear programming problem and obtain the optimal low-thrust rendezvous/interception trajectories. The rapid design and optimization algorithms developed in this paper are validated by three simulation cases with different performance indexes and boundary constraints.

Differential correction capability of the GTDS using TDRSS data

NASA Technical Reports Server (NTRS)

Liu, S. Y.; Soskey, D. G.; Jacintho, J.

1980-01-01

A differential correction (DC) capability was implemented in the Goddard Trajectory Determination System (GTDS) to process satellite tracking data acquired via the Tracking and Data Relay Satellite System (TRDRSS). Configuration of the TDRSS is reviewed, observation modeling is presented, and major features of the capability are discussed. The following types of TDRSS data can be processed by GTDS: two way relay range and Doppler measurements, hybrid relay range and Doppler measurements, one way relay Doppler measurements, and differenced one way relay Doppler measurements. These data may be combined with conventional ground based direct tracking data. By using Bayesian weighted least squares techniques, the software allows the simultaneous determination of the trajectories of up to four different satellites - one user satellite and three relay satellites. In addition to satellite trajectories, the following parameters can be optionally solved: for drag coefficient, reflectivity of a satellite for solar radiation pressure, transponder delay, station position, and biases.

Novice drivers' individual trajectories of driver behavior over the first three years of driving.

PubMed

Roman, Gabriela D; Poulter, Damian; Barker, Edward; McKenna, Frank P; Rowe, Richard

2015-09-01

Identifying the changes in driving behavior that underlie the decrease in crash risk over the first few months of driving is key to efforts to reduce injury and fatality risk in novice drivers. This study represented a secondary data analysis of 1148 drivers who participated in the UK Cohort II study. The Driver Behavior Questionnaire was completed at 6 months and 1, 2 and 3 years after licensure. Linear latent growth models indicated significant increases across development in all four dimensions of aberrant driving behavior under scrutiny: aggressive violations, ordinary violations, errors and slips. Unconditional and conditional latent growth class analyses showed that the observed heterogeneity in individual trajectories was explained by the presence of multiple homogeneous groups of drivers, each exhibiting specific trajectories of aberrant driver behavior. Initial levels of aberrant driver behavior were important in identifying sub-groups of drivers. All classes showed positive slopes; there was no evidence of a group of drivers whose aberrant behavior decreased over time that might explain the decrease in crash involvement observed over this period. Male gender and younger age predicted membership of trajectories with higher levels of aberrant behavior. These findings highlight the importance of early intervention for improving road safety. We discuss the implications of our findings for understanding the behavioral underpinnings of the decrease in crash involvement observed in the early months of driving. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Molecular analysis confirms the long-distance transport of Juniperus ashei pollen

PubMed Central

Mohanty, Rashmi Prava; Buchheim, Mark Alan; Anderson, James; Levetin, Estelle

2017-01-01

Although considered rare, airborne pollen can be deposited far from its place of origin under a confluence of favorable conditions. Temporally anomalous records of Cupressacean pollen collected from January air samples in London, Ontario, Canada have been cited as a new case of long-distance transport. Data on pollination season implicated Juniperus ashei (mountain cedar), with populations in central Texas and south central Oklahoma, as the nearest source of the Cupressacean pollen in the Canadian air samples. This finding is of special significance given the allergenicity of mountain cedar pollen. While microscopy is used extensively to identify particles in the air spora, pollen from all members of the Cupressaceae, including Juniperus, are morphologically indistinguishable. Consequently, we implemented a molecular approach to characterize Juniperus pollen using PCR in order to test the long-distance transport hypothesis. Our PCR results using species-specific primers confirmed that the anomalous Cupressacean pollen collected in Canada was from J. ashei. Forward trajectory analysis from source areas in Texas and the Arbuckle Mountains in Oklahoma and backward trajectory analysis from the destination area near London, Ontario were completed using models implemented in HYSPLIT4 (Hybrid Single-Particle Lagrangian Integrated Trajectory). Results from these trajectory analyses strongly supported the conclusion that the J. ashei pollen detected in Canada had its origins in Texas or Oklahoma. The results from the molecular findings are significant as they provide a new method to confirm the long-distance transport of pollen that bears allergenic importance. PMID:28273170

Developmental Trajectories of Anxiety Symptoms in Early Adolescence: The Influence of Anxiety Sensitivity

PubMed Central

Allan, Nicholas P.; Capron, Daniel W.; Lejuez, Carl W.; Reynolds, Elizabeth K.; MacPherson, Laura; Schmidt, Norman B.

2014-01-01

Children and adolescents seem to suffer from anxiety disorders at rates similar to adults. Interestingly, anxiety symptoms appear to generally decline over time within children as evidenced by lower rates in early and middle adolescence. There is some evidence that there may be heterogeneous subpopulations of adolescent children with different trajectories of anxiety symptoms, including a class of adolescents with elevated levels of anxiety that do not dissipate over time. Anxiety sensitivity has been identified as an important risk factor in the development of anxiety psychopathology. This study prospectively examined the development of anxiety symptoms in a sample of 277 adolescents (Mage=11.52; 44 % female, 56 % male) over a 3 year period including the influence of anxiety sensitivity on this development. Further, this study investigated whether there were distinct classes of adolescents based on their anxiety symptom trajectories and including anxiety sensitivity as a predictor. Consistent with other reports, findings indicated an overall decline in anxiety symptoms over time in the sample. However, three classes of adolescents were found with distinct anxiety symptom trajectories and anxiety sensitivity was an important predictor of class membership. Adolescents with elevated anxiety sensitivity scores were more likely to be classified as having high and increasing anxiety symptoms over time versus having moderate to low and decreasing anxiety symptoms over time. There are important implications for identification of adolescents and children who are at risk for the development of an anxiety disorder. PMID:24062146

Developmental trajectories of anxiety symptoms in early adolescence: the influence of anxiety sensitivity.

PubMed

Allan, Nicholas P; Capron, Daniel W; Lejuez, Carl W; Reynolds, Elizabeth K; MacPherson, Laura; Schmidt, Norman B

2014-05-01

Children and adolescents seem to suffer from anxiety disorders at rates similar to adults. Interestingly, anxiety symptoms appear to generally decline over time within children as evidenced by lower rates in early and middle adolescence. There is some evidence that there may be heterogeneous subpopulations of adolescent children with different trajectories of anxiety symptoms, including a class of adolescents with elevated levels of anxiety that do not dissipate over time. Anxiety sensitivity has been identified as an important risk factor in the development of anxiety psychopathology. This study prospectively examined the development of anxiety symptoms in a sample of 277 adolescents (M age = 11.52; 44 % female, 56 % male) over a 3 year period including the influence of anxiety sensitivity on this development. Further, this study investigated whether there were distinct classes of adolescents based on their anxiety symptom trajectories and including anxiety sensitivity as a predictor. Consistent with other reports, findings indicated an overall decline in anxiety symptoms over time in the sample. However, three classes of adolescents were found with distinct anxiety symptom trajectories and anxiety sensitivity was an important predictor of class membership. Adolescents with elevated anxiety sensitivity scores were more likely to be classified as having high and increasing anxiety symptoms over time versus having moderate to low and decreasing anxiety symptoms over time. There are important implications for identification of adolescents and children who are at risk for the development of an anxiety disorder.

Trajectories of posttraumatic growth and depreciation after two major earthquakes.

PubMed

Marshall, Emma M; Frazier, Patricia; Frankfurt, Sheila; Kuijer, Roeline G

2015-03-01

This study examined trajectories of posttraumatic growth or depreciation (i.e., positive or negative life change) in personal strength and relationships after 2 major earthquakes in Canterbury, New Zealand using group-based trajectory modeling. Participants completed questionnaires regarding posttraumatic growth or depreciation in personal strength and relationship domains 1 month after the first earthquake in September 2010 (N = 185) and 3 months (n = 156) and 12 months (n = 144) after the more severe February 2011 earthquake. Three classes of growth or depreciation patterns were found for both domains. For personal strength, most of the participants were grouped into a "no growth or depreciation" class and smaller proportions were grouped into either a "posttraumatic depreciation" or "posttraumatic growth" class. The 3 classes for relationships all reported posttraumatic growth, differing only in degree. None of the slopes were significant for any of the classes, indicating that levels of growth or depreciation reported after the first earthquake remained stable when assessed at 2 time points after the second earthquake. Multinomial logistic regression analyses examining pre- and postearthquake predictors of trajectory class membership revealed that those in the "posttraumatic growth" personal strength class were significantly younger and had significantly higher pre-earthquake mental health than those in the "posttraumatic depreciation" class. Sex was the only predictor of the relationship classes: No men were assigned to the "high posttraumatic growth" class. Implications and future directions are discussed. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

The Disillusionment of Students Denied Admission to a Preferred Major Viewed from the Perspective of a Psychological Theory of Alienation

ERIC Educational Resources Information Center

Barber, Clifton E.

2014-01-01

Why students respond differently when they are denied admission to a preferred academic major may be explained using a psychological theory of alienation. Using this theoretical perspective, three trajectories producing feelings of alienation are presented. The most intense of these trajectories, the process of disillusionment, is examined using a…

Trajectories of Depressive Symptoms and Externalizing Behaviors across Adolescence: Associations with Histories of Suicide Attempt and Ideation in Early Adulthood

ERIC Educational Resources Information Center

Kerr, David C. R.; Reinke, Wendy M.; Eddy, J. Mark

2013-01-01

We examined associations between adolescent problem trajectories and suicide risk outcomes in 361 community participants. Depressive symptoms (self-report) and externalizing behaviors (parent report) were assessed six times from grades 5 to 10. Parallel process linear growth curves indicated that lifetime suicide attempt history assessed to age 25…

Explicating the Role of Mathematical Tasks in Conceptual Learning: An Elaboration of the Hypothetical Learning Trajectory

ERIC Educational Resources Information Center

Simon, Martin A.; Tzur, Ron

2004-01-01

Simon's (1995) development of the construct of hypothetical learning trajectory (HLT) offered a description of key aspects of planning mathematics lessons. An HLT consists of the goal for the students' learning, the mathematical tasks that will be used to promote student learning, and hypotheses about the process of the students' learning.…

Does Attention Constrain Developmental Trajectories in Fragile X Syndrome? A 3-Year Prospective Longitudinal Study

ERIC Educational Resources Information Center

Cornish, Kim; Cole, Victoria; Longhi, Elena; Karmiloff-Smith, Annette; Scerif, Gaia

2012-01-01

Basic attentional processes and their impact on developmental trajectories in fragile X syndrome were assessed in a 3-year prospective study. Although fragile X syndrome is a monogenic X-linked disorder, there is striking variability in outcomes even in young boys with the condition. Attention is a key factor constraining interactions with the…

Multi-Target Tracking via Mixed Integer Optimization

DTIC Science & Technology

2016-05-13

solving these two problems separately, however few algorithms attempt to solve these simultaneously and even fewer utilize optimization. In this paper we...introduce a new mixed integer optimization (MIO) model which solves the data association and trajectory estimation problems simultaneously by minimizing...Kalman filter [5], which updates the trajectory estimates before the algorithm progresses forward to the next scan. This process repeats sequentially

FPGA Implementation of an Efficient Algorithm for the Calculation of Charged Particle Trajectories in Cosmic Ray Detectors

NASA Astrophysics Data System (ADS)

Villar, Xabier; Piso, Daniel; Bruguera, Javier D.

2014-02-01

This paper presents an FPGA implementation of an algorithm, previously published, for the the reconstruction of cosmic rays' trajectories and the determination of the time of arrival and velocity of the particles. The accuracy and precision issues of the algorithm have been analyzed to propose a suitable implementation. Thus, a 32-bit fixed-point format has been used for the representation of the data values. Moreover, the dependencies among the different operations have been taken into account to obtain a highly parallel and efficient hardware implementation. The final hardware architecture requires 18 cycles to process every particle, and has been exhaustively simulated to validate all the design decisions. The architecture has been mapped over different commercial FPGAs, with a frequency of operation ranging from 300 MHz to 1.3 GHz, depending on the FPGA being used. Consequently, the number of particle trajectories processed per second is between 16 million and 72 million. The high number of particle trajectories calculated per second shows that the proposed FPGA implementation might be used also in high rate environments such as those found in particle and nuclear physics experiments.

Examining Educational Climate Change Technology: How Group Inquiry Work with Realistic Scientific Technology Alters Classroom Learning

NASA Astrophysics Data System (ADS)

Bush, Drew; Sieber, Renee; Seiler, Gale; Chandler, Mark

2018-04-01

This study with 79 students in Montreal, Quebec, compared the educational use of a National Aeronautics and Space Administration (NASA) global climate model (GCM) to climate education technologies developed for classroom use that included simpler interfaces and processes. The goal was to show how differing climate education technologies succeed and fail at getting students to evolve in their understanding of anthropogenic global climate change (AGCC). Many available climate education technologies aim to convey key AGCC concepts or Earth systems processes; the educational GCM used here aims to teach students the methods and processes of global climate modeling. We hypothesized that challenges to learning about AGCC make authentic technology-enabled inquiry important in developing accurate understandings of not just the issue but how scientists research it. The goal was to determine if student learning trajectories differed between the comparison and treatment groups based on whether each climate education technology allowed authentic scientific research. We trace learning trajectories using pre/post exams, practice quizzes, and written student reflections. To examine the reasons for differing learning trajectories, we discuss student pre/post questionnaires, student exit interviews, and 535 min of recorded classroom video. Students who worked with a GCM demonstrated learning trajectories with larger gains, higher levels of engagement, and a better idea of how climate scientists conduct research. Students who worked with simpler climate education technologies scored lower in the course because of lower levels of engagement with inquiry processes that were perceived to not actually resemble the work of climate scientists.

Ares I-X Range Safety Flight Envelope Analysis

NASA Technical Reports Server (NTRS)

Starr, Brett R.; Olds, Aaron D.; Craig, Anthony S.

2011-01-01

Ares I-X was the first test flight of NASA's Constellation Program's Ares I Crew Launch Vehicle designed to provide manned access to low Earth orbit. As a one-time test flight, the Air Force's 45th Space Wing required a series of Range Safety analysis data products to be developed for the specified launch date and mission trajectory prior to granting flight approval on the Eastern Range. The range safety data package is required to ensure that the public, launch area, and launch complex personnel and resources are provided with an acceptable level of safety and that all aspects of prelaunch and launch operations adhere to applicable public laws. The analysis data products, defined in the Air Force Space Command Manual 91-710, Volume 2, consisted of a nominal trajectory, three sigma trajectory envelopes, stage impact footprints, acoustic intensity contours, trajectory turn angles resulting from potential vehicle malfunctions (including flight software failures), characterization of potential debris, and debris impact footprints. These data products were developed under the auspices of the Constellation's Program Launch Constellation Range Safety Panel and its Range Safety Trajectory Working Group with the intent of beginning the framework for the operational vehicle data products and providing programmatic review and oversight. A multi-center NASA team in conjunction with the 45th Space Wing, collaborated within the Trajectory Working Group forum to define the data product development processes, performed the analyses necessary to generate the data products, and performed independent verification and validation of the data products. This paper outlines the Range Safety data requirements and provides an overview of the processes established to develop both the data products and the individual analyses used to develop the data products, and it summarizes the results of the analyses required for the Ares I-X launch.

Ares I-X Range Safety Analyses Overview

NASA Technical Reports Server (NTRS)

Starr, Brett R.; Gowan, John W., Jr.; Thompson, Brian G.; Tarpley, Ashley W.

2011-01-01

Ares I-X was the first test flight of NASA's Constellation Program's Ares I Crew Launch Vehicle designed to provide manned access to low Earth orbit. As a one-time test flight, the Air Force's 45th Space Wing required a series of Range Safety analysis data products to be developed for the specified launch date and mission trajectory prior to granting flight approval on the Eastern Range. The range safety data package is required to ensure that the public, launch area, and launch complex personnel and resources are provided with an acceptable level of safety and that all aspects of prelaunch and launch operations adhere to applicable public laws. The analysis data products, defined in the Air Force Space Command Manual 91-710, Volume 2, consisted of a nominal trajectory, three sigma trajectory envelopes, stage impact footprints, acoustic intensity contours, trajectory turn angles resulting from potential vehicle malfunctions (including flight software failures), characterization of potential debris, and debris impact footprints. These data products were developed under the auspices of the Constellation's Program Launch Constellation Range Safety Panel and its Range Safety Trajectory Working Group with the intent of beginning the framework for the operational vehicle data products and providing programmatic review and oversight. A multi-center NASA team in conjunction with the 45th Space Wing, collaborated within the Trajectory Working Group forum to define the data product development processes, performed the analyses necessary to generate the data products, and performed independent verification and validation of the data products. This paper outlines the Range Safety data requirements and provides an overview of the processes established to develop both the data products and the individual analyses used to develop the data products, and it summarizes the results of the analyses required for the Ares I-X launch.

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

NASA Astrophysics Data System (ADS)

Wiacek, A.; Peter, T.; Lohmann, U.

2010-02-01

This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Without explicitly modelling dust emission and deposition processes, dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Practically none of the simulated air parcels reached regions where homogeneous ice nucleation can take place (T≲-40 °C) along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through regions supersaturated with respect to ice but subsaturated with respect to water, where "warm" (T≳-40 °C) ice clouds may form prior to supercooled water or mixed-phase clouds. The importance of "warm" ice clouds and the general influence of dust in the mixed-phase cloud region are highly uncertain due to considerable scatter in recent laboratory data from ice nucleation experiments, which we briefly review in this work. For "classical" cirrus-forming temperatures, our results show that only mineral dust IN that underwent mixed-phase cloud-processing previously are likely to be relevant, and, therefore, we recommend further systematic studies of immersion mode ice nucleation on mineral dust suspended in atmospherically relevant coatings.

Ab Initio Molecular Dynamics Studies on Substitution vs. Electron Transfer Reactions of Substituted Ketyl Radical Anions with Chloroalkanes: How Do the Two Products Form in a Borderline Mechanism?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamataka, H.; Aida, Misako; Dupuis, Michel

We present a qualitative analysis, based on ab initio molecular dynamics (MD) calculations, of the SN2/ET mechanistic spectrum for three reactions: (1) HC(CN)=O.- + CH3Cl, (2) HC(CN)=O.- + (CH3)2CHCl, and (3) H2C=O.- + CH3Cl, passing through their SN2-like transition states. The finite temperature (298 K) direct-MD simulations indicate that the trajectories for reaction 1 appear to have a propensity towards SN2 products, the propensity for trajectories for reaction 2 seems to be towards ET products, whereas trajectories for reaction 3 appear to show no particular propensity towards either ET or SN2 products. The mechanistic diversity is consistent with the electronmore » donating ability of the ketyl species and steric bulkiness of chloroalkanes. We find that the trajectories have characteristics that reflect strongly the types of process (SN2 trajectories in reactions 1 and 3 vs. ET trajectories in reactions 2 and 3). Trajectories that lead to SN2 products are simple with C-C bond formation and C-Cl bond breaking essentially completed within 50 fs. By contrast, trajectories leading to ET products are more complex with a sudden electron reorganization taking place within 15 - 30 fs and the major bonding changes and electron and spin reorganizations completed after 250 fs.« less

Distinct longitudinal patterns of absenteeism and their antecedents in full-time Australian employees.

PubMed

Magee, Christopher A; Caputi, Peter; Lee, Jeong Kyu

2016-01-01

This paper investigated distinct longitudinal trajectories of absenteeism over time, and underlying demographic, work, and health antecedents. Data from the Household, Income, and Labor Dynamics in Australia Survey were used; this is a panel study of a representative sample of Australian households. This paper focused on 2,481 full-time employees across a 5-year period. Information on annual sick leave and relevant sociodemographic, work, and health-related factors was collected through interviews and self-completed surveys. Growth mixture modeling indicated 4 distinct longitudinal patterns of absenteeism over time. The moderate absenteeism trajectory (34.8%) of the sample had 4-5 days of sick leave per year and was used as the reference group. The low absenteeism trajectory (33.5%) had 1-2 days of absenteeism per year, while the no absenteeism trajectory (23.6%) had very low rates of absenteeism (<1 day per year). Finally, a smaller trajectory accounting for 8.1% of the sample had high levels of absenteeism (>11 days per year). Compared with the moderate absenteeism trajectory, the high absenteeism trajectory was characterized by poor health; the no absenteeism and low absenteeism trajectories had better health but may also reflect processes relating to presenteeism. These results provide important insights into the nature of absenteeism in Australian employees, and suggest that different patterns of absenteeism over time could reflect a range of demographic, work, and health related factors. (c) 2016 APA, all rights reserved).

Entropic Movement Complexity Reflects Subjective Creativity Rankings of Visualized Hand Motion Trajectories

PubMed Central

Peng, Zhen; Braun, Daniel A.

2015-01-01

In a previous study we have shown that human motion trajectories can be characterized by translating continuous trajectories into symbol sequences with well-defined complexity measures. Here we test the hypothesis that the motion complexity individuals generate in their movements might be correlated to the degree of creativity assigned by a human observer to the visualized motion trajectories. We asked participants to generate 55 novel hand movement patterns in virtual reality, where each pattern had to be repeated 10 times in a row to ensure reproducibility. This allowed us to estimate a probability distribution over trajectories for each pattern. We assessed motion complexity not only by the previously proposed complexity measures on symbolic sequences, but we also propose two novel complexity measures that can be directly applied to the distributions over trajectories based on the frameworks of Gaussian Processes and Probabilistic Movement Primitives. In contrast to previous studies, these new methods allow computing complexities of individual motion patterns from very few sample trajectories. We compared the different complexity measures to how a group of independent jurors rank ordered the recorded motion trajectories according to their personal creativity judgment. We found three entropic complexity measures that correlate significantly with human creativity judgment and discuss differences between the measures. We also test whether these complexity measures correlate with individual creativity in divergent thinking tasks, but do not find any consistent correlation. Our results suggest that entropic complexity measures of hand motion may reveal domain-specific individual differences in kinesthetic creativity. PMID:26733896

Experimental investigation on underwater trajectory deviation of high-speed projectile with different nose shapes

NASA Astrophysics Data System (ADS)

Zhang, Wei; Huang, Wei; Gao, Yubo; Qi, Yafei; Hypervelocity Impact Research Center Team

2015-06-01

Laboratory-scaled oblique water entry experiments for the trajectory stability in the water column have been performed with four different nosed-projectiles at a range of velocities from 20m /s to 250 m /s . The slender projectiles are designed with flat, ogival, hemi-sperical, truncated-ogival noses to make comparisons on the trajectory deviation when they are launched at vertical and oblique impact angles (0°~25°). Two high-speed cameras that are positioned orthogonal to each other and normal to the column are employed to capture the entire process of projectiles' penetration. From the experimental results, the sequential images in two planes are presented to compare the trajectory deviation of different impact tests and the 3D trajectory models are extracted based on the location recorded by cameras. Considering the effect influenced by the impact velocities and noses of projectiles, it merited concluded that trajectory deviation is affected from most by impact angle, and least by impact velocities. Additionally, ogival projectiles tend to be more sensitive to oblique angle and experienced the largest attitude changing. National Natural Science Foundation of China (NO.: 11372088).

Calculation of Water Drop Trajectories to and About Arbitrary Three-Dimensional Bodies in Potential Airflow

NASA Technical Reports Server (NTRS)

Norment, H. G.

1980-01-01

Calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Any subsonic, external, non-lifting flow can be accommodated; flow into, but not through, inlets also can be simulated. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Code descriptions include operating instructions, card inputs and printouts for example problems, and listing of the FORTRAN codes. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits

NASA Astrophysics Data System (ADS)

Chantasri, Areeya; Kimchi-Schwartz, Mollie E.; Roch, Nicolas; Siddiqi, Irfan; Jordan, Andrew N.

2016-10-01

We experimentally and theoretically investigate the quantum trajectories of jointly monitored transmon qubits embedded in spatially separated microwave cavities. Using nearly quantum-noise-limited superconducting amplifiers and an optimized setup to reduce signal loss between cavities, we can efficiently track measurement-induced entanglement generation as a continuous process for single realizations of the experiment. The quantum trajectories of transmon qubits naturally split into low and high entanglement classes. The distribution of concurrence is found at any given time, and we explore the dynamics of entanglement creation in the state space. The distribution exhibits a sharp cutoff in the high concurrence limit, defining a maximal concurrence boundary. The most-likely paths of the qubits' trajectories are also investigated, resulting in three probable paths, gradually projecting the system to two even subspaces and an odd subspace, conforming to a "half-parity" measurement. We also investigate the most-likely time for the individual trajectories to reach their most entangled state, and we find that there are two solutions for the local maximum, corresponding to the low and high entanglement routes. The theoretical predictions show excellent agreement with the experimental entangled-qubit trajectory data.

A Hidden Markov Model for Single Particle Tracks Quantifies Dynamic Interactions between LFA-1 and the Actin Cytoskeleton

PubMed Central

Das, Raibatak; Cairo, Christopher W.; Coombs, Daniel

2009-01-01

The extraction of hidden information from complex trajectories is a continuing problem in single-particle and single-molecule experiments. Particle trajectories are the result of multiple phenomena, and new methods for revealing changes in molecular processes are needed. We have developed a practical technique that is capable of identifying multiple states of diffusion within experimental trajectories. We model single particle tracks for a membrane-associated protein interacting with a homogeneously distributed binding partner and show that, with certain simplifying assumptions, particle trajectories can be regarded as the outcome of a two-state hidden Markov model. Using simulated trajectories, we demonstrate that this model can be used to identify the key biophysical parameters for such a system, namely the diffusion coefficients of the underlying states, and the rates of transition between them. We use a stochastic optimization scheme to compute maximum likelihood estimates of these parameters. We have applied this analysis to single-particle trajectories of the integrin receptor lymphocyte function-associated antigen-1 (LFA-1) on live T cells. Our analysis reveals that the diffusion of LFA-1 is indeed approximately two-state, and is characterized by large changes in cytoskeletal interactions upon cellular activation. PMID:19893741

Monte Carlo tree search -based non-coplanar trajectory design for station parameter optimized radiation therapy (SPORT).

PubMed

Dong, Peng; Liu, Hongcheng; Xing, Lei

2018-06-04

An important yet challenging problem in LINAC-based rotational arc radiation therapy is the design of beam trajectory, which requires simultaneous consideration of delivery efficiency and final dose distribution. In this work, we propose a novel trajectory selection strategy by developing a Monte Carlo tree search (MCTS) algorithm during the beam trajectory selection process. Methods: To search through the vast number of possible trajectories, MCTS algorithm was implemented. In this approach, a candidate trajectory is explored by starting from a leaf node and sequentially examining the next level of linked nodes with consideration of geometric and physical constraints. The maximum Upper Confidence Bounds for Trees, which is a function of average objective function value and the number of times the node under testing has been visited, was employed to intelligently select the trajectory. For each candidate trajectory, we run an inverse fluence map optimization with an infinity norm regularization. The ranking of the plan as measured by the corresponding objective function value was then fed back to update the statistics of the nodes on the trajectory. The method was evaluated with a chest wall and a brain case, and the results were compared with the coplanar and noncoplanar 4pi beam configurations. Results: For both clinical cases, the MCTS method found effective and easy-to-deliver trajectories within an hour. As compared with the coplanar plans, it offers much better sparing of the OARs while maintaining the PTV coverage. The quality of the MCTS-generated plan is found to be comparable to the 4pi plans. Conclusion: AI based on MCTS is valuable to facilitate the design of beam trajectory and paves the way for future clinical use of non-coplanar treatment delivery. . © 2018 Institute of Physics and Engineering in Medicine.

Financial Strain, Trajectories of Marital Processes, and African American Newlyweds' Marital Instability

PubMed Central

Barton, Allen W.; Bryant, Chalandra M.

2016-01-01

The present study examined the longitudinal associations among financial strain, trajectories of marital processes, and increases in marital instability concerns among a sample of 280 African American newlywed couples followed over the first three years of marriage. Results from dyadic structural equation modeling revealed that financial strain experienced during the early years of marriage was associated with increased marital instability concerns for both husbands and wives. Latent growth curves of marital processes revealed mean declines in appraisals of spousal warmth and increases in appraisals of spousal hostility, with variability between individuals in rates of decline in warmth; further, wives' appraisals of spousal warmth covaried with levels of financial strain, such that high levels of financial strain were associated with steeper declines in spousal warmth appraisals. For both husbands and wives, rates of change in spousal warmth appraisals had a greater influence on increases in marital instability concerns than either starting levels of spousal warmth appraisals or financial strain. Findings highlight the long-term associations between external stress and trajectories of marital appraisals as well as their relative effects on marital distress. PMID:26998640

From medico-administrative databases analysis to care trajectories analytics: an example with the French SNDS.

PubMed

Drezen, Erwan; Guyet, Thomas; Happe, André

2018-02-01

Medico-administrative data like SNDS (Système National de Données de Santé) are not collected initially for epidemiological purposes. Moreover, the data model and the tools proposed to SNDS users make their in-depth exploitation difficult. We propose a data model, called the ePEPS model, based on healthcare trajectories to provide a medical view of raw data. A data abstraction process enables the clinician to have an intuitive medical view of raw data and to design a study-specific view. This view is based on a generic model of care trajectory, that is a sequence of time stamped medical events for a given patient. This model is combined with tools to manipulate care trajectories efficiently. © 2017 Société Française de Pharmacologie et de Thérapeutique.

Biased Brownian dynamics for rate constant calculation.

PubMed

Zou, G; Skeel, R D; Subramaniam, S

2000-08-01

An enhanced sampling method-biased Brownian dynamics-is developed for the calculation of diffusion-limited biomolecular association reaction rates with high energy or entropy barriers. Biased Brownian dynamics introduces a biasing force in addition to the electrostatic force between the reactants, and it associates a probability weight with each trajectory. A simulation loses weight when movement is along the biasing force and gains weight when movement is against the biasing force. The sampling of trajectories is then biased, but the sampling is unbiased when the trajectory outcomes are multiplied by their weights. With a suitable choice of the biasing force, more reacted trajectories are sampled. As a consequence, the variance of the estimate is reduced. In our test case, biased Brownian dynamics gives a sevenfold improvement in central processing unit (CPU) time with the choice of a simple centripetal biasing force.

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

NASA Astrophysics Data System (ADS)

Wiacek, A.; Peter, T.; Lohmann, U.

2010-09-01

This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T≲-40 °C) along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but subsaturated with respect to water, where so-called "warm ice clouds" (T≳-40 °C) theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice clouds" and the general influence of dust in the mixed-phase cloud region are highly uncertain due to both a considerable scatter in recent laboratory data from ice nucleation experiments, which we briefly review in this work, and due to uncertainties in sub-grid scale vertical transport processes unresolved by the present trajectory analysis. For "classical" cirrus-forming temperatures (T≲-40 °C), our results show that only mineral dust ice nuclei that underwent mixed-phase cloud-processing, most likely acquiring coatings of organic or inorganic material, are likely to be relevant. While the potential paucity of deposition ice nuclei shown in this work dimishes the possibility of deposition nucleation, the absence of liquid water droplets at T≲-40 °C makes the less explored contact freezing mechanism (involving droplet collisions with bare ice nuclei) highly inefficient. These factors together indicate the necessity of further systematic studies of immersion mode ice nucleation on mineral dust suspended in atmospherically relevant coatings.

Chaos in War: Is It Present and What Does It Mean?

DTIC Science & Technology

1994-06-01

the Poincare map. The results of this work indicated that chaos is, in fact, present in warfare. The implications of this result include IV...confirmed the validity of our software and provided us with the Poincare maps and the power spectrum. LTC Pentland of the School for Advanced...nearly identical initial conditions for the logistics equation 20 8 . Poincare map 22 9. Phase-space trajectories of chaotic systems 23 10

Operating Without a Safety Net: Gay Male Adolescents and Emerging Adults’ Experiences of Marginalization and Migration, and Implications for Theory of Syndemic Production of Health Disparities

PubMed Central

Bruce, Douglas; Harper, Gary W.

2011-01-01

Health disparities among gay men (HIV, substance use, depression) have been described as a mutually occurring “syndemic” that is socially produced through two overarching dynamics: marginalization and migration. Although the syndemic theory proposes a developmental trajectory, it has been largely based on epidemiological studies of adult gay men and has not been examined using qualitative data from gay male adolescents and emerging adults describing their developmental experience. We conducted interviews with 54 HIV-positive gay and bisexual male adolescents and emerging adults at four sites in the United States. This study provides examples of developmental trajectories that help explain the early onset of socially produced health disparities among some gay male adolescents and emerging adults, but also the development of risk factors that may follow some gay men into adulthood. PMID:21398621

Household Composition and Longitudinal Health Outcomes for Older Mexican Return Migrants

PubMed Central

Mudrazija, Stipica; López-Ortega, Mariana; Vega, William A.; Robledo, Luis Miguel Gutiérrez; Sribney, William

2016-01-01

Mexican return migrant population is increasing, yet our knowledge about their lives after resettlement in Mexico remains fragmentary. Using 2001–2012 longitudinal data from the Mexican Health and Aging Study, we investigate difference in household composition for older migrants who returned from the United States compared to nonmigrants. Furthermore, we fit a Cox proportional hazards model to assess the relationship between household composition and health and functional trajectories of return migrants and nonmigrants. The results indicate that return migrants with long duration of U.S. stay have different household composition than nonmigrants or short-term migrants: On average, they have smaller household size, including fewer females who may be available to offer assistance to older adults. Presence of middle-age females in the household has positive effects on health and functional trajectories. We highlight implications of this research for policy makers in Mexico and the United States. PMID:26966255

Teacher student relationship quality type in elementary grades: Effects on trajectories for achievement and engagement

PubMed Central

Wu, Jiun-yu; Hughes, Jan N.; Kwok, Oi-man

2010-01-01

Teacher, peer, and student reports of the quality of the teacher-student relationship were obtained for an ethnically diverse and academically at-risk sample of 706 second and third grade students. Cluster analysis identified four types of relationships based on the consistency of child reports of support and conflict in the relationship with reports of others: Congruent positive, Congruent Negative, Incongruent Child Negative and Incongruent Child Positive. The cluster solution evidenced good internal consistency and construct validity. Cluster membership predicted growth trajectories for teacher-rated engagement and standardized achievement scores over the following three years, above prior performance. The predictive associations between child reports of teacher support and conflict and outcomes depended on whether child reports were consistent or inconsistent with reports of others. Study findings have implications for theory development, assessment of teacher-student relationships, and teacher professional development. PMID:20728688

Real-time evolution of non-Gaussian cumulants in the QCD critical regime

NASA Astrophysics Data System (ADS)

Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi

2015-09-01

We derive a coupled set of equations that describe the nonequilibrium evolution of cumulants of critical fluctuations for spacetime trajectories on the crossover side of the QCD phase diagram. In particular, novel expressions are obtained for the nonequilibrium evolution of non-Gaussian skewness and kurtosis cumulants. UBy utilizing a simple model of the spacetime evolution of a heavy-ion collision, we demonstrate that, depending on the relaxation rate of critical fluctuations, skewness and kurtosis can differ significantly in magnitude as well as in sign from equilibrium expectations. Memory effects are important and shown to persist even for trajectories that skirt the edge of the critical regime. We use phenomenologically motivated parametrizations of freeze-out curves and of the beam-energy dependence of the net baryon chemical potential to explore the implications of our model study for the critical-point search in heavy-ion collisions.

Developmental course of impulsivity and capability from age 10 to age 25 as related to trajectory of suicide attempt in a community cohort.

PubMed

Kasen, Stephanie; Cohen, Patricia; Chen, Henian

2011-04-01

Hierarchical linear models were used to examine trajectories of impulsivity and capability between ages 10 and 25 in relation to suicide attempt in 770 youths followed longitudinally: intercepts were set at age 17. The impulsivity measure assessed features of urgency (e.g., poor control, quick provocation, and disregard for external constraints); the capability measure assessed aspects of self-esteem and mastery. Compared to nonattempters, attempters reported significantly higher impulsivity levels with less age-related decline, and significantly lower capability levels with less age-related increase. Independent of other risks, suicide attempt was related significantly to higher impulsivity between ages 10 and 25, especially during the younger years, and lower capability. Implications of those findings for further suicidal behavior and preventive/intervention efforts are discussed. © 2011 The American Association of Suicidology.

A tale of two contexts: U.S. migration and the labor force trajectories of Mexican women.

PubMed

Flippen, Chenoa A; Parrado, Emilio A

2015-01-01

Even though women have long participated in Mexico-U.S. migration studies assessing the labor market implications of international mobility for women are rare. Especially lacking are studies that follow a life-course approach and compare employment trajectories across contexts and in connection with other transitions. Using life-history data collected in Mexico and the United States, we explore the impact of migration on women's employment, focusing on how the determinants of employment vary across contexts. We show that U.S. residence eliminates or even reverses the employment returns to education found in Mexico, and that the constraints imposed on women's work by marriage are actually stronger in the U.S. We also explicitly connect migration to other life-course events, documenting how the impact of context varies not only by marital status but also by where women's unions were formed.

A tale of two contexts: U.S. migration and the labor force trajectories of Mexican women1

PubMed Central

Flippen, Chenoa A.; Parrado, Emilio A.

2015-01-01

Even though women have long participated in Mexico-U.S. migration studies assessing the labor market implications of international mobility for women are rare. Especially lacking are studies that follow a life-course approach and compare employment trajectories across contexts and in connection with other transitions. Using life-history data collected in Mexico and the United States, we explore the impact of migration on women’s employment, focusing on how the determinants of employment vary across contexts. We show that U.S. residence eliminates or even reverses the employment returns to education found in Mexico, and that the constraints imposed on women’s work by marriage are actually stronger in the U.S. context. We also explicitly connect migration to other life-course events, documenting how the impact of context varies not only by marital status but also by where women’s unions were formed. PMID:26843706

Real time evolution of non-Gaussian cumulants in the QCD critical regime

DOE PAGES

Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi

2015-09-23

In this study, we derive a coupled set of equations that describe the nonequilibrium evolution of cumulants of critical fluctuations for spacetime trajectories on the crossover side of the QCD phase diagram. In particular, novel expressions are obtained for the nonequilibrium evolution of non-Gaussian skewness and kurtosis cumulants. UBy utilizing a simple model of the spacetime evolution of a heavy-ion collision, we demonstrate that, depending on the relaxation rate of critical fluctuations, skewness and kurtosis can differ significantly in magnitude as well as in sign from equilibrium expectations. Memory effects are important and shown to persist even for trajectories thatmore » skirt the edge of the critical regime. We use phenomenologically motivated parametrizations of freeze-out curves and of the beam-energy dependence of the net baryon chemical potential to explore the implications of our model study for the critical-point search in heavy-ion collisions.« less

Trajectories of Neighborhood Attainment after Prison

PubMed Central

Lee, Keun Bok; Harding, David J.; Morenoff, Jeffrey D.

2018-01-01

A potentially important but understudied aspect of prisoner reentry is the neighborhood environments experienced by formerly incarcerated people. We know that many formerly incarcerated people return to very disadvantaged neighborhood environments and that returning to disadvantaged neighborhoods after prison increases the risk of recidivism and reduces employment. Yet very little is known about the social, economic, and institutional processes that sort formerly incarcerated people into different neighborhoods after release or their trajectories of neighborhood attainment over time. Motivated by a conceptualization of prisoner reentry and reintegration as a process that unfolds over time, we examine trajectories of neighborhood environments after release. Motivated by the literatures on neighborhood attainment, social capital, and the role of criminal justice institutions in structuring the lives of former prisoners, we examine sources of variation in neighborhood attainment. We use administrative data from the Michigan Department of Corrections on formerly incarcerated people paroled in 2003 and followed for two years after release. Descriptive results from a latent class trajectory model show that most white and black formerly incarcerated people experience flat trajectories, with little upward or downward residential mobility over time. Findings from multi-level growth curve models suggest that institutional factors are particularly important for the neighborhood attainment of whites, while human capital and social ties are particularly important for blacks. Among both blacks and whites, pre-prison and first post-prison neighborhood conditions exhibit a strong association with post-prison neighborhood attainment, although these associations are larger for blacks than whites. PMID:28705357

Differential contributions to the interception of occluded ballistic trajectories by the temporoparietal junction, area hMT/V5+, and the intraparietal cortex.

PubMed

Delle Monache, Sergio; Lacquaniti, Francesco; Bosco, Gianfranco

2017-09-01

The ability to catch objects when transiently occluded from view suggests their motion can be extrapolated. Intraparietal cortex (IPS) plays a major role in this process along with other brain structures, depending on the task. For example, interception of objects under Earth's gravity effects may depend on time-to-contact predictions derived from integration of visual signals processed by hMT/V5+ with a priori knowledge of gravity residing in the temporoparietal junction (TPJ). To investigate this issue further, we disrupted TPJ, hMT/V5+, and IPS activities with transcranial magnetic stimulation (TMS) while subjects intercepted computer-simulated projectile trajectories perturbed randomly with either hypo- or hypergravity effects. In experiment 1 , trajectories were occluded either 750 or 1,250 ms before landing. Three subject groups underwent triple-pulse TMS (tpTMS, 3 pulses at 10 Hz) on one target area (TPJ | hMT/V5+ | IPS) and on the vertex (control site), timed at either trajectory perturbation or occlusion. In experiment 2 , trajectories were entirely visible and participants received tpTMS on TPJ and hMT/V5+ with same timing as experiment 1 tpTMS of TPJ, hMT/V5+, and IPS affected differently the interceptive timing. TPJ stimulation affected preferentially responses to 1-g motion, hMT/V5+ all response types, and IPS stimulation induced opposite effects on 0-g and 2-g responses, being ineffective on 1-g responses. Only IPS stimulation was effective when applied after target disappearance, implying this area might elaborate memory representations of occluded target motion. Results are compatible with the idea that IPS, TPJ, and hMT/V5+ contribute to distinct aspects of visual motion extrapolation, perhaps through parallel processing. NEW & NOTEWORTHY Visual extrapolation represents a potential neural solution to afford motor interactions with the environment in the face of missing information. We investigated relative contributions by temporoparietal junction (TPJ), hMT/V5+, and intraparietal cortex (IPS), cortical areas potentially involved in these processes. Parallel organization of visual extrapolation processes emerged with respect to the target's motion causal nature: TPJ was primarily involved for visual motion congruent with gravity effects, IPS for arbitrary visual motion, whereas hMT/V5+ contributed at earlier processing stages. Copyright © 2017 the American Physiological Society.

Back to the Future: Consistency-Based Trajectory Tracking

NASA Technical Reports Server (NTRS)

Kurien, James; Nayak, P. Pandurand; Norvig, Peter (Technical Monitor)

2000-01-01

Given a model of a physical process and a sequence of commands and observations received over time, the task of an autonomous controller is to determine the likely states of the process and the actions required to move the process to a desired configuration. We introduce a representation and algorithms for incrementally generating approximate belief states for a restricted but relevant class of partially observable Markov decision processes with very large state spaces. The algorithm presented incrementally generates, rather than revises, an approximate belief state at any point by abstracting and summarizing segments of the likely trajectories of the process. This enables applications to efficiently maintain a partial belief state when it remains consistent with observations and revisit past assumptions about the process' evolution when the belief state is ruled out. The system presented has been implemented and results on examples from the domain of spacecraft control are presented.

Anxiety, Depression, and Cigarette Smoking: A Transdiagnostic Vulnerability Framework to Understanding Emotion-Smoking Comorbidity

PubMed Central

Leventhal, Adam M.; Zvolensky, Michael J.

2014-01-01

Research into the comorbidity between emotional psychopathology and cigarette smoking has often focused upon anxiety and depression’s manifest symptoms and syndromes, with limited theoretical and clinical advancement. This paper presents a novel framework to understanding emotion-smoking comorbidity. We propose that transdiagnostic emotional vulnerabilities—core biobehavioral traits reflecting maladaptive responses to emotional states that underpin multiple types of emotional psychopathology—link various anxiety and depressive psychopathologies to smoking. This framework is applied in a review and synthesis of the empirical literature on three trandiagnostic emotional vulnerabilities implicated in smoking: (1) anhedonia (Anh; diminished pleasure/interest in response to rewards); (2) anxiety sensitivity (AS; fear of anxiety-related sensations); and (3) distress tolerance (DT; ability to withstand distressing states). We conclude that Anh, AS, and DT collectively: (a) underpin multiple emotional psychopathologies; (b) amplify smoking’s anticipated and actual affect enhancing properties and other mechanisms underlying smoking; (c) promote progression across the smoking trajectory (i.e., initiation, escalation/progression, maintenance, cessation/relapse); and (d) are promising targets for smoking intervention. After existing gaps are identified, an integrative model of transdiagnostic processes linking emotional psychopathology to smoking is proposed. The model’s key premise is that Anh amplifies smoking’s anticipated and actual pleasure-enhancing effects, AS amplifies smoking’s anxiolytic effects, and poor DT amplifies smoking’s distress terminating effects. Collectively, these processes augment the reinforcing properties of smoking for individuals with emotional psychopathology to heighten risk of smoking initiation, progression, maintenance, cessation avoidance, and relapse. We conclude by drawing clinical and scientific implications from this framework that may generalize to other comorbidities. PMID:25365764

Improving absolute gravity estimates by the L p -norm approximation of the ballistic trajectory

NASA Astrophysics Data System (ADS)

Nagornyi, V. D.; Svitlov, S.; Araya, A.

2016-04-01

Iteratively re-weighted least squares (IRLS) were used to simulate the L p -norm approximation of the ballistic trajectory in absolute gravimeters. Two iterations of the IRLS delivered sufficient accuracy of the approximation without a significant bias. The simulations were performed on different samplings and perturbations of the trajectory. For the platykurtic distributions of the perturbations, the L p -approximation with 3  <  p  <  4 was found to yield several times more precise gravity estimates compared to the standard least-squares. The simulation results were confirmed by processing real gravity observations performed at the excessive noise conditions.

Rapid Generation of Optimal Asteroid Powered Descent Trajectories Via Convex Optimization

NASA Technical Reports Server (NTRS)

Pinson, Robin; Lu, Ping

2015-01-01

This paper investigates a convex optimization based method that can rapidly generate the fuel optimal asteroid powered descent trajectory. The ultimate goal is to autonomously design the optimal powered descent trajectory on-board the spacecraft immediately prior to the descent burn. Compared to a planetary powered landing problem, the major difficulty is the complex gravity field near the surface of an asteroid that cannot be approximated by a constant gravity field. This paper uses relaxation techniques and a successive solution process that seeks the solution to the original nonlinear, nonconvex problem through the solutions to a sequence of convex optimal control problems.

Optimization of cooling strategy and seeding by FBRM analysis of batch crystallization

NASA Astrophysics Data System (ADS)

Zhang, Dejiang; Liu, Lande; Xu, Shijie; Du, Shichao; Dong, Weibing; Gong, Junbo

2018-03-01

A method is presented for optimizing the cooling strategy and seed loading simultaneously. Focused beam reflectance measurement (FBRM) was used to determine the approximating optimal cooling profile. Using these results in conjunction with constant growth rate assumption, modified Mullin-Nyvlt trajectory could be calculated. This trajectory could suppress secondary nucleation and has the potential to control product's polymorph distribution. Comparing with linear and two step cooling, modified Mullin-Nyvlt trajectory have a larger size distribution and a better morphology. Based on the calculating results, the optimized seed loading policy was also developed. This policy could be useful for guiding the batch crystallization process.

A simulation technique for predicting thickness of thermal sprayed coatings

NASA Technical Reports Server (NTRS)

Goedjen, John G.; Miller, Robert A.; Brindley, William J.; Leissler, George W.

1995-01-01

The complexity of many of the components being coated today using the thermal spray process makes the trial and error approach traditionally followed in depositing a uniform coating inadequate, thereby necessitating a more analytical approach to developing robotic trajectories. A two dimensional finite difference simulation model has been developed to predict the thickness of coatings deposited using the thermal spray process. The model couples robotic and component trajectories and thermal spraying parameters to predict coating thickness. Simulations and experimental verification were performed on a rotating disk to evaluate the predictive capabilities of the approach.

Survey and Method for Determination of Trajectory Predictor Requirements

NASA Technical Reports Server (NTRS)

Rentas, Tamika L.; Green, Steven M.; Cate, Karen Tung

2009-01-01

A survey of air-traffic-management researchers, representing a broad range of automation applications, was conducted to document trajectory-predictor requirements for future decision-support systems. Results indicated that the researchers were unable to articulate a basic set of trajectory-prediction requirements for their automation concepts. Survey responses showed the need to establish a process to help developers determine the trajectory-predictor-performance requirements for their concepts. Two methods for determining trajectory-predictor requirements are introduced. A fast-time simulation method is discussed that captures the sensitivity of a concept to the performance of its trajectory-prediction capability. A characterization method is proposed to provide quicker, yet less precise results, based on analysis and simulation to characterize the trajectory-prediction errors associated with key modeling options for a specific concept. Concept developers can then identify the relative sizes of errors associated with key modeling options, and qualitatively determine which options lead to significant errors. The characterization method is demonstrated for a case study involving future airport surface traffic management automation. Of the top four sources of error, results indicated that the error associated with accelerations to and from turn speeds was unacceptable, the error associated with the turn path model was acceptable, and the error associated with taxi-speed estimation was of concern and needed a higher fidelity concept simulation to obtain a more precise result

Linking trajectories of land change, land degradation processes and ecosystem services.

PubMed

Smiraglia, D; Ceccarelli, T; Bajocco, S; Salvati, L; Perini, L

2016-05-01

Land Degradation (LD) is a complex phenomenon resulting in a progressive reduction in the capacity of providing ecosystem services (ES). Landscape transformations promoting an unsustainable use of land often reveal latent processes of LD. An evaluation carried out in respect to the different ecosystem services is nowadays regarded as the most appropriate approach for assessing the effects of LD. The aim of this study is to develop an evaluation framework for identifying the linkages between land changes, LD processes and ES and suggesting Sustainable Land Management (SLM) options suited to reverse (or mitigate) LD impact. A SWOT analysis was carried out with the aim to identify internal and external factors that are favorable (or unfavorable) to achieve the proposed SLM actions. The study areas are the Fortore valley and the Valpadana, in Italy. The main trajectory identified for the Fortore valley is related to land abandonment due to population aging and the progressive emigration started in the 1950s. The most relevant LD processes are soil erosion and geomorphological instability, affecting regulating services such as natural hazard and erosion control. SLM options should consider interventions to contrast geomorphological instability, the promotion of climate smart agriculture and of typical products, and an efficient water resources management. The main trajectories identified for Valpadana are related to urban expansion and farmland abandonment and, as a consequence, land take due to anthropogenic pressure and woodland expansion as the main LD process. The reduction of food production was identified as the most relevant provisioning service affected. SLM should envisage best practices finalized to water saving and soil consumption reduction: efficient irrigation solutions, climate smart agriculture and zero sealing practices. This study highlights the diagnostic value of the suggested approach where LD processes are elicited from land change trajectories determining specific impacts on ES and providing operational support for the implementation of SLM options. Copyright © 2015 Elsevier Inc. All rights reserved.

Piloted simulation of an air-ground profile negotiation process in a time-based Air Traffic Control environment

NASA Technical Reports Server (NTRS)

Williams, David H.; Green, Steven M.

1993-01-01

Historically, development of airborne flight management systems (FMS) and ground-based air traffic control (ATC) systems has tended to focus on different objectives with little consideration for operational integration. A joint program, between NASA's Ames Research Center (Ames) and Langley Research Center (Langley), is underway to investigate the issues of, and develop systems for, the integration of ATC and airborne automation systems. A simulation study was conducted to evaluate a profile negotiation process (PNP) between the Center/TRACON Automation System (CTAS) and an aircraft equipped with a four-dimensional flight management system (4D FMS). Prototype procedures were developed to support the functional implementation of this process. The PNP was designed to provide an arrival trajectory solution which satisfies the separation requirements of ATC while remaining as close as possible to the aircraft's preferred trajectory. Results from the experiment indicate the potential for successful incorporation of aircraft-preferred arrival trajectories in the CTAS automation environment. Fuel savings on the order of 2 percent to 8 percent, compared to fuel required for the baseline CTAS arrival speed strategy, were achieved in the test scenarios. The data link procedures and clearances developed for this experiment, while providing the necessary functionality, were found to be operationally unacceptable to the pilots. In particular, additional pilot control and understanding of the proposed aircraft-preferred trajectory, and a simplified clearance procedure were cited as necessary for operational implementation of the concept.

Racializing Drug Design: Implications of Pharmacogenomics for Health Disparities

PubMed Central

Lee, Sandra Soo-Jin

2005-01-01

Current practices of using “race” in pharmacogenomics research demands consideration of the ethical and social implications for understandings of group difference and for efforts to eliminate health disparities. This discussion focuses on an “infrastructure of racialization” created by current trajectories of research on genetic differences among racially identified groups, the use of race as a proxy for risk in clinical practice, and increasing interest in new market niches by the pharmaceutical industry. The confluence of these factors has resulted in the conflation of genes, disease, and race. I argue that public investment in pharmacogenomics requires careful consideration of current inequities in health status and social and ethical concerns over reifying race and issues of distributive justice. PMID:16257939

Simulation of wave packet tunneling of interacting identical particles

NASA Astrophysics Data System (ADS)

Lozovik, Yu. E.; Filinov, A. V.; Arkhipov, A. S.

2003-02-01

We demonstrate a different method of simulation of nonstationary quantum processes, considering the tunneling of two interacting identical particles, represented by wave packets. The used method of quantum molecular dynamics (WMD) is based on the Wigner representation of quantum mechanics. In the context of this method ensembles of classical trajectories are used to solve quantum Wigner-Liouville equation. These classical trajectories obey Hamiltonian-like equations, where the effective potential consists of the usual classical term and the quantum term, which depends on the Wigner function and its derivatives. The quantum term is calculated using local distribution of trajectories in phase space, therefore, classical trajectories are not independent, contrary to classical molecular dynamics. The developed WMD method takes into account the influence of exchange and interaction between particles. The role of direct and exchange interactions in tunneling is analyzed. The tunneling times for interacting particles are calculated.

Real-time fuzzy inference based robot path planning

NASA Technical Reports Server (NTRS)

Pacini, Peter J.; Teichrow, Jon S.

1990-01-01

This project addresses the problem of adaptive trajectory generation for a robot arm. Conventional trajectory generation involves computing a path in real time to minimize a performance measure such as expended energy. This method can be computationally intensive, and it may yield poor results if the trajectory is weakly constrained. Typically some implicit constraints are known, but cannot be encoded analytically. The alternative approach used here is to formulate domain-specific knowledge, including implicit and ill-defined constraints, in terms of fuzzy rules. These rules utilize linguistic terms to relate input variables to output variables. Since the fuzzy rulebase is determined off-line, only high-level, computationally light processing is required in real time. Potential applications for adaptive trajectory generation include missile guidance and various sophisticated robot control tasks, such as automotive assembly, high speed electrical parts insertion, stepper alignment, and motion control for high speed parcel transfer systems.