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PubMed2006

Exact cone beam reconstruction for a saddle trajectory.

We propose an exact shift-invariant filtered backprojection (FBP) algorithm for inversion of cone beam (CB) data in the case where the source trajectory is a saddle. The algorithm allows for axial truncation of the cone beam data. The algorithm involves only one family of filtering lines on the detector plane, and it does not depend on the existence of pi-lines. The algorithm is derived from a general formula in Pack and Noo (2005 Inverse Problems 21 1105-20). We also give the steps to implement the algorithm for planar detector geometry and discuss how to select the parameter of the saddle and the size of the detector when the trajectory is a standard saddle. The algorithm is tested by simulation studies.

Algorithms↗
PubMed2004

Biophysical parameters influence actin-based movement, trajectory, and initiation in a cell-free system.

Using a biochemically complex cytoplasmic extract to reconstitute actin-based motility of Listeria monocytogenes and polystyrene beads coated with the bacterial protein ActA, we have systematically varied a series of biophysical parameters and examined their effects on initiation of motility, particle speed, speed variability, and path trajectory. Bead size had a profound effect on all aspects of motility, with increasing size causing slower, straighter movement and inhibiting symmetry-breaking. Speed also was reduced by extract dilution, by addition of methylcellulose, and paradoxically by addition of excess skeletal muscle actin, but it was enhanced by addition of nonmuscle (platelet) actin. Large, persistent individual variations in speed were observed for all conditions and their relative magnitude increased with extract dilution, indicating that persistent alterations in particle surface properties may be responsible for intrinsic speed variations. Trajectory curvature was increased for smaller beads and also for particles moving in the presence of methylcellulose or excess skeletal muscle actin. Symmetry breaking and movement initiation occurred by two distinct modes: either stochastic amplification of local variation for small beads in concentrated extracts, or gradual accumulation of strain in the actin gel for large beads in dilute extracts. Neither mode was sufficient to enable spherical particles to break symmetry in the cytoplasm of living cells.

Actins↗
PubMed1989

Analysis of dynamics trajectories of DNA and DNA-drug complexes.

A FORTRAN-77 program is described which was applied for analysis of optimized structures and computer-generated dynamics trajectories of DNA and DNA-drug complexes. The CORDAN program (coordinates analysis) also can be used for various manipulations of DNA-drug complexes, i.e. inversion of asymmetric sites or rebuilding the structure of the intercalator, among others. These procedures can find application in drug design. Analysis of dynamics trajectory of neocarzinostatin antibiotic (NCS) intercalated to the A-DNA form of 5'GGATGGGAG:5'CTCCCATCC is presented. The procedures described can be used for detailed analysis of dynamics structures of DNA and their complexes with intercalating drugs.

Base Sequence↗
PubMed2005

Using a Bayesian latent growth curve model to identify trajectories of positive affect and negative events following myocardial infarction.

Positive and negative affect data are often collected over time in psychiatric care settings, yet no generally accepted means are available to relate these data to useful diagnoses or treatments. Latent class analysis attempts data reduction by classifying subjects into one of K unobserved classes based on observed data. Latent class models have recently been extended to accommodate longitudinally observed data. We extend these approaches in a Bayesian framework to accommodate trajectories of both continuous and discrete data. We consider whether latent class models might be used to distinguish patients on the basis of trajectories of observed affect scores, reported events, and presence or absence of clinical depression.

Bayes Theorem↗
PubMed2005

From caregiving to bereavement: trajectories of depressive symptoms among wife and daughter caregivers.

This study examined the trajectory of depressive symptoms for wife and daughter caregivers during the transition from caregiving to bereavement, and it investigated whether the trajectory varies by caregivers' caregiving stress, social support, and background characteristics. Hierarchical linear modeling was used to analyze four-wave longitudinal data collected from 157 wife and daughter caregivers who lost elderly relatives to death. Results show that, on average, caregivers experience increasing depressive symptoms as their care recipients approach death, and they experience decreasing symptoms after. Care recipients' problematic behavior and caregivers' kinship, income, and feelings of overload moderate the change in depressive symptoms during the transition. Services to support caregivers should target specific groups of caregivers, based on caregiving experience and background characteristics, at times when they are most in need.

Bereavement↗
PubMed2004

Socioeconomic trajectories across the life course and health outcomes in midlife: evidence for the accumulation hypothesis?

BACKGROUND: Recent research in social epidemiology has established the importance of considering the accumulation of advantage and disadvantage across the life course when examining adult health outcomes. This paper examines (1) accumulation across trichotomous categories of socioeconomic position (SEP), and (2) accumulation in analysis stratified by adult SEP. METHODS: Data are from the Whitehall II study. Each participant was categorized as having high (0), intermediate (1), or low (2) SEP at three time points in the life course, leading to 27 socioeconomic trajectories. These trajectories were summarized to yield a scale ranging from 0 (high SEP at all three time points) to 6 (low SEP at all three time points). Logistic regression was used to examine odds of incident coronary heart disease (CHD), poor mental and physical functioning, and minor psychiatric disorder. RESULTS: There was a graded linear relationship between accumulation of socioeconomic exposure and health. Men with a score of 6 had increased odds of CHD (2.53, 95% CI: 1.3, 5.1), poor physical functioning (2.19, 95% CI: 1.4, 4.1), and poor mental functioning (2.60, 95% CI: 1.4, 4.9) compared with men with a score of 0. In women there was an accumulation effect for CHD and physical functioning. No cumulative effect of SEP on minor psychiatric disorder was observed. The effects of accumulation were weaker in analyses stratified by adult SEP, with early deprivation followed by high adult SEP particularly detrimental for CHD. CONCLUSIONS: The health effects of socioeconomic disadvantage accumulate over the life course. In addition to accumulation effects, analysis stratified by adult SEP also provided support for the critical period and the pathway model.

Adult↗
PubMed1999

Protein malnutrition affects the growth trajectories of the craniofacial skeleton in rats.

To investigate the effects of protein malnutrition on a normal growth trajectory, we radiographed Rattus norvegicus from 22 d (weaning) and continuing past adult size. We took measurements from longitudinal radiographs of rats fed a control diet and littermates fed an isocaloric low protein experimental diet. A Gompertz model was fit to each individual rat for body weight and 22 measurements of the craniofacial skeleton, producing parameters that described the rate and timing of growth. We tested for differences in these parameters due to diet, sex and litter with a mixed-model three-way ANOVA. Allometric analysis examined the scaling relationships between and within various regions of the skull. For most measurements, final sizes predicted by the model were not significantly different between rats fed the two diets, although the differences in final measurements showed small, but significant differences in growth between rats in the two diet groups. The instantaneous initial rate of growth, maximum rate of growth and deceleration of growth were significantly higher in the control rats for every measurement. Rats fed the low protein diet grew for a significantly longer period of time. The shape of the neurocranium was relatively conserved between diet groups; however, rats fed the low protein diet had shorter and relatively wider skulls than the controls. These results suggest that functional demands of the viscerocranium were greater after birth, and that growth in this area was faster. The viscerocranium reached functional adult proportions earlier and was therefore more susceptible to epigenetic perturbations such as dietary protein level. Protein malnutrition did not affect many aspects of adult size, but strongly altered the growth trajectory to achieve that size.

Analysis of Variance↗
PubMed2004

Growth in young Filipino children predicts schooling trajectories through high school.

Several studies link childhood malnutrition to adverse schooling outcomes, including delayed or diminished enrollment and increased grade repetition. However, the effects of nutrition on schooling trajectories are obscured by the cross-sectional nature of most previous research and the complex array of other phenomena that affect schooling outcomes. We explored the association between height-for-age Z-score (HAZ) at 2 y and schooling trajectory among 2198 children from the Cebu Longitudinal Health and Nutrition Survey. Parity, parental education, maternal height, household assets, environmental cleanliness, presence of electricity, and household income were identified as potential confounders. Crude and adjusted logistic and multinomial regressions of schooling outcomes (entrance age, grade repetition, and grades completed) were conducted. Entrance age and IQ were evaluated as potential mediators between HAZ and schooling outcomes. After adjustment for confounders, greater height for age protected against late enrollment among both boys and girls and predicted early enrollment among boys. Taller children were less likely to repeat grades [girls OR = 0.78 (0.67, 0.89); boys OR = 0.86 (0.74, 0.99)] and less likely to drop out during grade school rather than graduate from high school [girls OR = 0.74 (0.56, 0.98; boys OR = 0.66 (0.51, 0.84)]. Models predicting the changes in school outcomes associated with a change in overall height from -2 to 0 SD of HAZ were simulated. Absolute probability of late enrollment dropped substantially, from 6% for both boys and girls to 2% for boys and 1% for girls. Absolute grade repetition dropped approximately 7% for boys and 9% for girls. Improving early childhood nutrition may have long-lasting educational benefits, increasing the likelihood of high school completion in developing countries.

Aging↗
PubMed1992

Foot trajectory in human gait: a precise and multifactorial motor control task.

The trajectory of the heel and toe during the swing phase of human gait were analyzed on young adults. The magnitude and variability of minimum toe clearance and heel-contact velocity were documented on 10 repeat walking trials on 11 subjects. The energetics that controlled step length resulted from a separate study of 55 walking trials conducted on subjects walking at slow, natural, and fast cadences. A sensitivity analysis of the toe clearance and heel-contact velocity measures revealed the individual changes at each joint in the link-segment chain that could be responsible for changes in those measures. Toe clearance was very small (1.29 cm) and had low variability (about 4 mm). Heel-contact velocity was negligible vertically and small (0.87 m/s) horizontally. Six joints in the link-segment chain could, with very small changes (+/- 0.86 degrees - +/- 3.3 degrees), independently account for toe clearance variability. Only one muscle group in the chain (swing-phase hamstring muscles) could be responsible for altering the heel-contact velocity prior to heel contact. Four mechanical power phases in gait (ankle push-off, hip pull-off, knee extensor eccentric power at push-off, and knee flexor eccentric power prior to heel contact) could alter step length and cadence. These analyses demonstrate that the safe trajectory of the foot during swing is a precise endpoint control task that is under the multisegment motor control of both the stance and swing limbs.

Adult↗
PubMed1997

Transformation of the intended direction of movement during continuous motor trajectories.

Chronometric and neurophysiological studies have demonstrated that mentally transforming the intended direction of a pointing movement is a time-consuming process, the duration of which increases with the angle of rotation. If the same time-consuming process occurred while tracing a curved trajectory, it would affect the time course of the movement. The data from subjects drawing simple figures match well the predictions made, and support the hypothesis that a time-consuming process of transformation of the intended movement direction operates during the production of continuous trajectories. This biologically inspired hypothesis provides a functional explanation for the relation between speed of the movement and curvature of the path. In addition, it contrasts with the view of continuous movements as essentially oscillatory motions.

Adult↗
PubMed2001

Caregivers' insights on the dying trajectory in hematology oncology.

It is increasingly acknowledged in the research literature that palliative care is not offered to patients with a hematologic malignancy. The evidence indicates that patients are not dying at home or in the comfort of the hospice setting but are more likely to end up in the high-tech care of an intensive care unit. The holistic, compassionate care of the hospice/palliative care philosophy is not routinely made available to either these patients or the families who care for them. However, little is known about what the end-of-life experience is for such patients and their families and how they are managing to negotiate their dying experience in a system that is designed to cure not to palliate. In particular, there is a dearth of information on what happens to the caregivers during what is characteristically a prolonged and difficult period of sustained caring within the high-tech system. This discussion presents findings from recent research that is beginning to document the experience of the dying trajectory for patients from these diagnostic groups and their families. The hope and expectation from such research is that the information will make a contribution to building multidisciplinary plans of care for hematologic malignancies during the dying trajectory, to ensure that patients and their families are appropriately referred to the palliative system or, at least, are given sensitive palliative care within the curative system.

Adolescent↗
PubMed1989

The trajectory of cognitive development in males with fragile X syndrome.

The trajectory of cognitive development in males with fragile X syndrome was identified in a cross-sectional study of 56 males and in a smaller, longitudinal study of 10 fragile X males. Results from both studies indicated steady cognitive growth until late childhood and early adolescence (10 to 15 years of age), at which point mental age plateaued and IQ declined. Males with higher initial IQ scores manifested more IQ decline than those with initial lower levels of intelligence. The trajectories of IQ differ from those in other etiological groups and mixed groups of retarded individuals. Results have direct implications for intervention strategies with fragile X males. Parents and teachers should be informed about the possibility of an early plateau in mental age, the impact this may have on the child's academic performance, and that the plateau and IQ decline may not be apparent in the child's adaptive behaviors.

Adolescent↗
PubMed2002

Childhood behavioral profiles leading to adolescent conduct disorder: risk trajectories for boys and girls.

OBJECTIVE: To examine the link between childhood behavioral dimensions and adolescent conduct disorder (CD) among a large sample of boys and girls monitored longitudinally. METHOD: Teachers rated the behaviors of 1,569 children every year between kindergarten and grade 6. On the basis of these seven yearly ratings, groups of children who followed distinct trajectories on three behavioral dimensions--hyperactivity, fearfulness, and helpfulness--were identified with a semiparametric statistical analysis. Children were then categorized into one of eight behavioral profiles, representing different combinations of the trajectories. Logistic regressions were used to estimate the relation between the profiles and CD in adolescence (mean = 15.7 years). RESULTS: Boys had a significant risk for CD if they were hyperactive (odds ratio [OR] = 4.27; 95% confidence interval [CI], 1.8-10.16); hyperactive and unhelpful (OR = 2.83; CI, 1.07-7.46); or hyperactive, fearless, and unhelpful (OR = 3.93; CI, 1.27-12.17). Girls had a significant risk for CD only if they were both hyperactive and unhelpful (OR = 4.61; CI, 1.31-16.24). More boys than girls exhibited profiles of risk and met criteria for CD in adolescence. CONCLUSIONS: Sex-specific childhood behavioral profiles that represented risk for CD in adolescence were identified. There were sex differences in the prevalence of the childhood profiles representing risk for CD.

Adolescent↗
PubMed1998

Physical symptom trajectories following trauma exposure: longitudinal findings from the normative aging study.

This study modeled physical symptom trajectories from ages 30 to 75 in 1079 older male military veterans who were assessed every 3 to 5 years since the 1960s. Combat exposure and noncombat trauma were used to define four groups: no trauma (N = 249), noncombat trauma only (N = 333), combat only (N = 152), and both combat and noncombat trauma (N = 345). Number of symptoms on the Cornell Medical Index physical symptom scale increased 29% per decade. Men who had experienced either combat or noncombat trauma did not differ from nonexposed men, but those who had experienced both combat and noncombat trauma had 16% more symptoms across all ages. There were no differences in age-related trajectories as a function of trauma history. In cross-sectional analysis, men with combat and noncombat trauma had more posttraumatic stress disorder symptoms, but not more depression symptoms, than men with either no trauma or noncombat trauma only. Discussion focuses on the importance of considering physical as well as psychological outcomes of exposure to traumatic events.

Adult↗
PubMedDate not supplied

Symptom and activities of daily living trajectory in multiple sclerosis: a 10-year study.

BACKGROUND: Symptom control in chronic illness is not merely a matter of medical management as the patient and family must rely on their own judgment, wisdom, and ingenuity for controlling symptoms. The absence in the literature regarding the effects of multiple sclerosis (MS) as perceived by afflicted people and their family members led to the 10-year longitudinal study. OBJECTIVES: To study patient self-report data to determine whether particular interventions may be needed to enhance the individual's comfort and functional levels. METHODS: The chronic illness trajectory of three groups of people with MS (< or =5 years of diagnosis, n=49; >5 to 10 years, n=36; and >10 years, n=68) was examined over a 10-year period. Serial self-assessments of the subjects' prevalence of MS-related symptoms (motor, brain stem, sensory, elimination, mental/emotional) and level of activities of daily living (ADL) functioning (fine and gross motor activities, sensory/communication, socializing/recreation, intimacy) were obtained annually. Profiles illustrating the subject's symptom and ADL pattern were also returned annually to each subject. RESULTS: Using 10-year average scores, study findings indicated no group differences relative to symptoms but showed significant group differences in all ADL functions. Separate group within-year (1, 3, 5, 7, 10) comparisons reflected significant increases in motor, brain stem, and elimination symptoms together with a decline in all ADL functions for specific groups. CONCLUSIONS: Medical data suggest, on average, a continuous downward trajectory beginning in the first years of illness or at approximately 36 to 37 years of age. In contrast, in this research, patient self-reports of fine and gross motor ADL, a correlate of neurologically based disability evaluations, reflect that relatively major decline begins after 5 years post-diagnosis and after age 40 for subjects recruited primarily from nonclinical sites.

Activities of Daily Living↗
PubMed2007

Trajectory of traumatic stress symptoms in the aftermath of extreme natural disaster: a study of adult thai survivors of the 2004 Southeast Asian earthquake and tsunami.

This study investigated the trajectory of traumatic stress symptoms in the aftermath of the 2004 Southeast Asian earthquake-tsunami. A total of 265 adult Thai survivors were assessed at 2 weeks and 6 months following the earthquake-tsunami. The percentages of survivors reporting traumatic stress symptoms were 22% at 2 weeks and 30% at 6 months postdisaster. Four trajectories of traumatic stress symptoms were identified: 12% of survivors presented with chronic stress symptoms, 18% had a delayed onset, 10% showed improvement, and the remaining 60% maintained a stable emotional equilibrium. Among survivors, the chronic group was the oldest, the delayed group reported the lowest level of perceived government support, and the resilient group experienced the fewest postdisaster psychiatric symptoms. Results pointed to the need to broaden the conceptualization of postdisaster stress responding as well as to establish disaster psychiatry and related mental health activities in the region.

Adaptation, Psychological↗
PubMed1984

The relation between soma position and fibre trajectory of neurons in the mesencephalic trigeminal nucleus of Xenopus laevis.

In adult Xenopus laevis the mandibular and ophthalmic branches of the trigeminal nerve were backfilled with CoCl2 or cobaltous lysine and whole brains silver intensified to reveal neurons of the mesencephalic Vth nucleus (mes. V). The nucleus contains about 100 cells arranged in a band extending arch-like from the ventrolateral margin of the optic tectum to the midline. Many cells possess a small number of short dendritic processes that arborize in the tectal neuropil; in some cells one dendrite terminates within the ependyma or ventricle. A single axon arises from each cell and courses in layer 7 to the margin of the tectum. Axon collaterals arise close to the cell body to terminate principally within layer 6, but occasionally also in layers 8 and 9. Collaterals occurring more caudally terminate in layer 6. These findings suggest that mes. V cells acts as tectal interneurons as well as conveying somatosensory information to the tectum from the mouth region. In the dorsal roof of the tectum the trajectory of a fibre is related to the distance of the soma from the midline. Mes. V cells located at the lateral end of the nucleus possess axons that course initially in a mediolateral direction before turning along the ventrolateral margin of the tectum. Cells positioned close to the midline have axons that project rostrocaudally the entire length of the tectum. The axons of cells located at intermediate positions within the nucleus course at correspondingly oblique angles through the dorsal roof of the tectum. Thus in this area there is a more or less 90 degrees rang in the orientation of mes. V fibres to the longitudinal axis. It is proposed that this topographical relationship between soma position and axon trajectory arises through a developmental mechanism, in which mes. V fibres grow during larval life sequentially into the medial zone of tectal growth and become subsequently displaced rostrolaterally, owing to the further addition of tectal tissue medially, through an angle dependent upon the parent cell's date of birth.

Animals↗
PubMed2025

Multi-Polygenic prediction of Frailty and its Trajectories highlights Chronic Pain, Rheumatoid Arthritis, and Educational Attainment pathways.

Frailty is a complex ageing-related trait with a growing evidence base for genetic influence. While a single polygenic score (PGS) for frailty has shown predictive value, few studies have examined the joint effect of multiple genetic risks. This study used a multi-polygenic score (MPS) approach to evaluate the combined and relative contributions of 26 PGSs to frailty, measured via the Frailty Index (FI), in two UK cohorts aged 65 and older: the English Longitudinal Study of Ageing (ELSA) and the Lothian Birth Cohort 1936 (LBC1936). Using elastic net regression with repeated cross-validation, we identified chronic pain and depressive symptoms PGSs as the strongest risk predictors of cross-sectional frailty status, while educational attainment, parental longevity, and rheumatoid arthritis PGSs were protective. Compared to single PGS models, MPS models provided improved prediction of frailty levels, explaining up to 4.7% of variance in frailty status - an improvement over the best single PGS (2.5%). To assess whether PGSs also predicted longitudinal frailty progression, we applied generalized additive mixed models (GAMMs) to model age-related trajectories. In ELSA, five PGSs (chronic pain, depressive symptoms, rheumatoid arthritis, educational attainment, and parental death) significantly interacted with age, influencing the rate of frailty change. In LBC1936, consistent though weaker effects were observed for chronic pain and education PGSs. These findings show that polygenic liability shapes both frailty levels and trajectories in later life. Our results support the use of multi-trait genomic models to improve risk prediction and understanding of frailty's complex aetiology.

Journal Article↗