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PubMed2001

Trajectory studies of S(N)2 nucleophilic substitution. 8. Central barrier dynamics for gas phase Cl(-) + CH(3)Cl.

Quasiclassical direct dynamics trajectories, calculated at the MP2/6-31G level of theory, are used to study the central barrier dynamics for the C1(-) + CH(3)Cl S(N)2 reaction. Extensive recrossings of the central barrier are observed in the trajectories. The dynamics of the Cl(-)-CH(3)Cl complex is non-RRKM and transition state theory (TST) is predicted to be an inaccurate model for calculating the Cl(-) + CH(3)Cl S(N)2 rate constant. Direct dynamics trajectories also show that Cl(-) + CH(3)Cl trajectories, which collide backside along the S(N)2 reaction path, do not form the Cl(-)-CH(3)Cl complex. This arises from weak coupling between the Cl(-)-CH(3)Cl intermolecular and CH(3)Cl intramolecular modes. The trajectory results are very similar to those of a previous trajectory study, based on a HF/6-31G* analytic potential energy function, which gives a less accurate representation of the central barrier region of the Cl(-) + CH(3)Cl reaction than does the MP2/6-31G* level of theory used here. Experiments are suggested for investigating the non-RRKM and non-TST dynamics predicted by the trajectories.

Journal Article↗
PubMed2003

Trajectories leading to school-age conduct problems.

The present study applied a semiparametric mixture model to a sample of 284 low-income boys to model developmental trajectories of overt conduct problems from ages 2 to 8. As in research on older children, 4 developmental trajectories were identified: a persistent problem trajectory, a high-level desister trajectory, a moderate-level desister trajectory, and a persistent low trajectory. Follow-up analyses indicated that initially high and low groups were differentiated in early childhood by high child fearlessness and elevated maternal depressive symptomatology. Persistent problem and high desister trajectories were differentiated by high child fearlessness and maternal rejecting parenting. The implications of the results for early intervention research are discussed, with an emphasis on the identification of at-risk parent-child dyads.

Adolescent↗
PubMed2006

Co-occurring delinquency and depressive symptoms of adolescent boys and girls: a dual trajectory modeling approach.

Co-occurring trajectories of delinquent behavior and depressive symptoms and their correlates were examined in a longitudinal sample of 985 middle-adolescent boys and girls (mean age = 15.54 years at Time 1). Dual trajectory analysis was used to identify the co-occurring trajectories. For boys (n = 472), 4 delinquency and 4 depression trajectory groups were found. For girls (n = 513), 3 delinquency and 3 depression trajectory groups were identified. The linkage between co-occurring trajectories was higher for girls than for boys. Stressful life events and childhood precursors of the outcomes predicted trajectory group membership for both genders fairly consistently. Findings suggest heterogeneity in developmental courses of delinquent behavior and depressive symptoms across adolescent boys and girls.

Adolescent↗
PubMed2001

Mothers' evolving relationships with doctors and nurses during the chronic childhood illness trajectory.

AIMS: In this paper the evolution of mothers' relationships with doctors and nurses during the chronic childhood illness trajectory is explored and discussed and the implications for child health care are considered. The discussion reports one aspect of a qualitative study that sought to determine whether time of diagnosis influenced mothers' coping across the illness trajectory. BACKGROUND: The quality of relationships between mothers, who are usually the primary carers, and nursing and medical staff is central to the experience of coping with chronic childhood illness. Mothers need to develop expertise in a wide range of technical skills and knowledge of complex health care issues, while also coming to terms with the uncertainty of a condition with an unpredictable trajectory. Attempts to understand the significance of relationships between those living with chronic illness and staff have highlighted a number of factors that may influence the degree to which they are viewed as satisfactory. The way staff communicate with families has been identified as one of the mediating processes through which the quality of such is determined. DESIGN: Mothers of 15 children diagnosed presymptomatically and 14 children diagnosed postsymptomatically with the chronic illness Vesicoureteric Reflux (VUR) were interviewed to assess and compare coping strategies across the trajectory. Mothers' written consent was obtained and interviews were tape-recorded, transcribed and analysed using the 'Framework Technique'. FINDINGS AND CONCLUSION: The need to develop and sustain trusting relationships with staff was reported as a continual source of stress for mothers. The formation of satisfactory alliances, based on mutual respect and good communication early in the trajectory, in particular during the prediagnostic phase, was found to be instrumental in coping and competence development during the later chronic phase of the trajectory. Further research is needed to map prospectively the evolution of relationships between mothers and staff across the trajectory.

Adaptation, Psychological↗
PubMed2005

Spatiotemporal consistency of trajectories in gymnastics: a three-dimensional analysis of flic-flac.

Sport performance during the execution of closed skills combines specific body and limb movements into codified patterns where stability and consistency may be more important than variability. Repeated sport movements can be investigated to assess the consistency of body trajectories. More consistent trajectories will result in more repeatable movements. The present study quantified the short-term consistency of body trajectories during the performance of the backward flic-flac, a technique of floor gymnastics. Nine experienced gymnasts (six men, three women), all of national level, performed 10 repetitions of backward flic-flac. An optoelectronic instrument was used for the detection of the three-dimensional movement of 13 body landmarks. The spatiotemporal consistency of repeated landmark trajectories was measured by the standard deviation between standardized trajectories. The results showed smaller standard deviation (larger consistency between landmark trajectories) in female than in male gymnasts. The analysis of the consistency of landmark trajectories could help gymnasts indicating which parts of the body do not repeat a selected movement with sufficient accuracy.

Adolescent↗
PubMed2005

Optic-flow-based perception of two-dimensional trajectories and the effects of a single landmark.

Human observers can detect their heading direction on a short time scale on the basis of optic flow. We investigated the visual perception and reconstruction of visually travelled two-dimensional (2-D) trajectories from optic flow, with and without a landmark. As in our previous study, seated, stationary subjects wore a head-mounted display in which optic-flow stimuli were shown that simulated various manoeuvres: linear or curvilinear 2-D trajectories over a horizontal plane, with observer orientation either fixed in space, fixed relative to the path, or changing relative to both. Afterwards, they reproduced the perceived manoeuvre with a model vehicle, whose position and orientation were recorded. Previous results had suggested that our stimuli can induce illusory percepts when translation and yaw are unyoked. We tested that hypothesis and investigated how perception of the travelled trajectory depends on the amount of yaw and the average path-relative orientation. Using a structured visual environment instead of only dots, or making available additional extra-retinal information, can improve perception of ambiguous optic-flow stimuli. We investigated the amount of necessary structuring, specifically the effect of additional visual and/or extra-retinal information provided by a single landmark in conditions where illusory percepts occur. While yaw was perceived correctly, the travelled path was less accurately perceived, but still adequately when the simulated orientation was fixed in space or relative to the trajectory. When the amount of yaw was not equal to the rotation of the path, or in the opposite direction, subjects still perceived orientation as fixed relative to the trajectory. This caused trajectory misperception because yaw was wrongly attributed to a rotation of the path: path perception is governed by the amount of yaw in the manoeuvre. Trajectory misperception also occurs when orientation is fixed relative to a curvilinear path, but not tangential to it. A single landmark could improve perception. Our results confirm and extend previous findings that, for unambiguous perception of ego-motion from optic flow, additional information is required in many cases, which can take the form of fairly minimal, visual information.

Adult↗
PubMedDate not supplied

Personality risk factors associated with trajectories of tobacco use.

The purpose of this longitudinal, prospective study was to evaluate trajectories of smoking in a cohort of African-American and Puerto Rican young adults and describe personality and behavioral factors associated with specific smoking trajectory group membership. Participants consisted of African-American and Puerto Rican male and female young adults (N = 451, mean age 26) from an inner-city community. Data were collected at four time points over a period of 13 years using structured interviews. Interviews took place within the schools and the participants' homes. Scales with adequate psychometric properties were adapted from previously validated measures. Variables that were examined for this study came from the domains of internalizing behaviors, externalizing behaviors, drug use, and demographic information. Data were analyzed using latent growth mixture modeling to explore discrete smoking trajectories. Logistic regression analyses were then used to examine the risk factors associated with the various smoking trajectory groups. Four trajectory groups were determined to best fit the data: nonsmokers, maturing-out smokers, late-starting smokers, and early-starting continuous smokers. Subjects who were unconventional, experienced intrapersonal distress, and used alcohol and illegal drugs were more likely to belong to one of the smoking trajectory groups than to the nonsmoking group. The early-starting continuous group scored highest on these personal risk attributes. The long-term impact of unconventional behavior, intrapersonal distress, and drug use on developmental trajectories of smoking support the importance of early intervention and prevention.

Adolescent↗
PubMed2003

Active control of the growth trajectory of broiler chickens based on online animal responses.

The objective of the research reported here was to control the growth trajectory of broiler chickens during the production process based on an adaptive compact dynamic process model. More specifically, the daily feed supply was calculated, based on a model-based control algorithm, with the aim of following a previously defined target growth trajectory as close as possible. For the modeling of the dynamic growth response of broiler chickens to the control input, feed supply, an online parameter estimation was used. The developed control algorithm was able to grow the birds according to different target trajectories ranging from restricted (final BW of 1,800 g and 1,945 g in experiments 1 and 3, respectively) to compensatory growth trajectories (final BW of 2,400 g and 2,100 g in experiments 2 and 4, respectively). The mean relative error (MRE) between the different predefined target growth trajectories and the realized growth trajectories ranged from 3.7% to 6.0%. With a few exceptions, the numerical values of feed conversion ratio and mortality after wk 1 were lower and the values of uniformity index were higher in the controlled groups compared with animals fed ad libitum. As a conclusion, it can be stated that integration of dynamic data-based modeling approaches with new hardware and sensing techniques to measure information from the animals should make it possible to control broiler growth trajectories.

Algorithms↗
PubMed2003

Straight-forward versus anatomic trajectory technique of thoracic pedicle screw fixation: a biomechanical analysis.

STUDY DESIGN: A biomechanical study on cadaveric thoracic vertebrae using pullout strength, insertional torque, and bone mineral density to determine the optimal sagittal trajectory of thoracic pedicle screws. OBJECTIVE: To perform a biomechanical study on cadaveric thoracic vertebrae using insertional torque, pullout strength, and bone mineral density to determine the optimal biomechanical sagittal trajectory for placement thoracic pedicle screws. We compared the straight-forward (paralleling the vertebral endplate) with anatomic trajectory (directed along the true anatomic axis of the pedicle). METHODS: Thirty cadaveric thoracic vertebrae were harvested and evaluated with dual-energy x-ray absorptiometry to assess bone mineral density. Matched, fixed-head pedicle screws were then randomly assigned by side and placed using the straight-forward or anatomic technique under fluoroscopic visualization while recording the maximum insertional torque. Pullout strength testing was then performed. RESULTS: The maximum insertional torque for the straight-forward technique was 2.58 +/- 0.14 (SE) in pounds, whereas the anatomic technique averaged 1.86 +/- 0.14 (SE) in pounds (P = 0.0005). The maximum insertional torque at the neurocentral junction for the straight-forward technique averaged 1.89 +/- 0.17 (SE) in-lbs. (73% of maximum insertional torque), whereas the anatomic trajectory averaged 1.39 +/- 0.11 (SE) in pounds (75% of maximum insertional torque) (P = 0.007). The average pullout strength using a straight-forward trajectory was 611 +/- 50 (SE) N compared to the anatomic trajectory, which averaged 481 +/- 54 (SE) N (P = 0.034). The pullout strength correlated with mean bone mineral density for both the straight-forward (r = 0.461, P = 0.027) and anatomic (r = 0.598, P = 0.004) techniques. CONCLUSIONS: The straight-forward technique results in a 39% increase in maximum insertional torque and a 27% increase in pullout strength compared to the anatomic technique. The maximum insertional torque at the neurocentral junction resulted in a 36% increase using the straight-forward technique versus the anatomic trajectory. Bone mineral density directly correlates with pullout strength for both techniques.

Absorptiometry, Photon↗
PubMed2006

Trajectories of symptoms and impairment for pediatric patients with functional abdominal pain: a 5-year longitudinal study.

OBJECTIVE: This prospective study characterizes trajectories of symptoms and impairment in pediatric patients with abdominal pain not associated with identifiable organic disease. METHOD: The Children's Somatization Inventory and the Functional Disability Inventory were administered four times over 5 years to 132 patients (6-18 years old) seen in a pediatric gastroenterology clinic. Individual trajectories were empirically grouped and correlates of trajectory group membership at baseline were evaluated. RESULTS: A model with three unique trajectories was found to adequately fit both symptom and impairment data. Two trajectories indicated relatively long-term improvement and one indicated continued high levels of symptoms and impairment. At baseline, the long-term risk group did not have the most severe pain but had significantly more anxiety, depression, lower perceived self-worth, and more negative life events. CONCLUSIONS: These results indicate that several distinct trajectories of relatively long-term outcomes may exist in children with functional abdominal pain. One trajectory indicated long-term risk for a high level of symptoms and impairment. Psychosocial correlates of long-term risk for physical symptoms and impairment, such as child-reported stress and internalizing symptoms, may be useful for treatment planning.

Abdominal Pain↗
PubMed2006

Wound-healing trajectories as outcome measures of venous stasis ulcer treatment.

Outcome measures of venous ulcer healing are not uniformly accepted. Stringent criteria of 100% closure fail to provide information of healing over the entire span of repair. Wound-healing trajectories (plot of percentage of wound closure versus time of wound treatment) were constructed for 232 patients treated in eight clinical trials at two independent wound care/research centres. Trajectories were constructed for ulcers that totally healed (100% closure) and those that did not (<100% closure) over a 20-week period. Kaplan-Meier survival plots determined the percentage of patients achieving total healing versus time of treatment. The wound-healing trajectories were almost identical for patients achieving complete ulcer healing, as were the trajectories for patients with less than 100% closure. The trajectories for the ulcers healing completely were significantly different from those with <100% closure. Only 60% of all patients achieved 100% closure by 20 weeks. Using linear regression, it was predicted that it would take 31 weeks for all patients to achieve total healing. Total healing is an inadequate outcome measure for healing of venous stasis ulcers. Clinical trials using this measure would require excessive time periods. As wound-healing trajectories for patients treated at two centres mimic one another, shifting the wound-healing trajectory from one of impaired healing to one of a more ideal healing course may be considered a better outcome measure for determining healing of venous stasis ulcers.

Bandages↗
PubMed1996

Relationship of firing intervals of human motor units to the trajectory of post-spike after-hyperpolarization and synaptic noise.

1. Interspike interval distributions from human motor units of a variety of muscles were analysed to assess the role of synaptic noise in excitation. The time course of the underlying post-spike after-hyperpolarization (AHP) was deduced by applying a specially developed transform to the interval data. Different firing rates were studied both by varying the firing voluntarily, and by selecting subpopulations of spikes for a given firing rate from long recordings with slight variations in frequency. 2. At low firing rates the interval histograms had an exponential tail. Thus at long intervals, the motoneurone was randomly excited by noise and its post-spike AHP was complete. This contrasts with the firing produced by intracellular current injection in the cat, when the membrane potential increases linearly until threshold is reached. The interval histogram was therefore analysed with the aid of a model of synaptic excitation to deduce the mean 'trajectory' of membrane voltage in the last part of the interspike interval. 3. The computer model, described in the Appendix, was used to determine the effect of the mean level of membrane potential on the probability of a spike being excited, per unit time, during an on-going interspike interval. All variables were treated as voltages, with synaptic noise simulated by time-smoothed Gaussian noise. This enabled an interval distribution to be transformed into a segment of the underlying trajectory of the membrane potential; the potential was expressed in terms of the noise amplitude and the spike threshold. 4. At low firing rates, the equilibrium value of the membrane voltage trajectory lay well below threshold; the deviation typically corresponded to the standard deviation of the noise or more. The noise standard deviation was estimated to be about 2 mV. 5. With increasing mean firing rate, the near-threshold portion of the trajectory obtainable from the histogram occurred earlier, was steeper and rose to a higher level. Trajectories for different firing rates fell on the same curve after shifting them vertically by varying amounts. The curve was taken to represent the AHP of the motoneurone and was closely exponential. The shift of the trajectory gave its mean synaptic drive. The duration of the AHP varied between units and was longer than average for units from soleus muscle. 6. Further modelling showed that summation of noise with the AHP can explain the well-known changes in discharge variability that occur as firing rate increases. 7. It is concluded that synaptic noise plays a major role in the excitation of tonically firing human motoneurones and that the noiseless motoneurone with a linear trajectory provides an inadequate model for the conscious human. This is of interest in relation to various standard measures of human motor unit activity such as short-term synchronization.

Action Potentials↗
PubMed2004

Dot trajectories in the superposition of random screens: analysis and synthesis.

Moiré effects that occur in the superposition of aperiodic layers such as correlated random dot screens are known as Glass patterns. One of the most interesting properties of such moiré effects, which clearly distinguish them from their periodic counterparts, is undoubtedly the appearence in the superposition of intriguing microstructure dot alignments, also known as dot trajectories. These dot trajectories may have different geometric shapes, depending on the transformations undergone by the superposed layers. In the case of simple linear transformations such as layer rotations or layer scalings, the resulting dot trajectories are rather simple (circular, radial, spiral, elliptic, hyperbolic, linear, etc.); but in more complex layer transformations the dot trajectories can have much more interesting and surprising shapes. A full mathematical analysis of the dot trajectories, their morphology, and their various properties is provided. Furthermore, it is shown how the approach also allows us to synthesize correlated random screens that give in their superposition dot trajectories having any desired geometric shapes. Finally, it is also explained why such dot trajectories are visible only in superpositions of aperiodic screens but not in superpositions of periodic screens.

Journal Article↗
PubMed1996

Getting drunk and growing up: trajectories of frequent binge drinking during the transition to young adulthood.

OBJECTIVE: The purpose of this study was: (1) to identify different trajectories of frequent binge drinking during the transition to young adulthood; (2) to validate the trajectories by relating them to behaviors and attitudes concerning alcohol and other drug use; and (3) to distinguish among the trajectories according to demographic characteristics and lifestyle experiences typical of the transition to young adulthood. METHOD: Four waves of national panel data were obtained from the Monitoring the Future project; 9,945 weighted cases from the 1976-85 high school senior year cohorts were surveyed at biennial intervals between ages 18 and 24. Frequent binge drinking was defined as having five or more drinks in a row at least twice in the past two weeks. RESULTS: Six distinct frequent binge drinking trajectory groups were specified a priori and confirmed with cluster analysis: Never, Rare, Chronic, Decreased, Increased and "Fling." Repeated measures ANOVAS revealed that the trajectories corresponded to patterns of change and stability in problems with alcohol, attitudes about heavy drinking, peer heavy drinking and illicit drug use. Results from logistic regression analyses predicting diverging and converging trajectories provided some support for the general hypothesis that trajectories of Chronic and Increased frequent binge drinking over time are associated with difficulties in negotiating the transition to young adulthood. CONCLUSIONS: The findings provide strong evidence for wide developmental variation in drinking patterns in the population, variation that is obscured by more aggregate-level considerations. The developmental variation in frequent binge drinking during the transition to young adulthood reflects systematic variation in success and difficulties with negotiating the transition.

Adolescent↗
PubMed2004

Adolescents' alcohol and drug use trajectories in the year following treatment.

OBJECTIVE: Beyond the initial relapse episode, little is known about short-term patterns of alcohol and other drug use in treated adolescents. This study characterized treated teens' short-term alcohol and other drug use trajectories over 1-year follow-up. METHOD: Adolescents (N = 110, ages 12-18, 65% male, 94% white) recruited from addictions treatment, with a current DSM-IV alcohol diagnosis, reported on daily alcohol and other drug use in monthly telephone contacts over 1-year follow-up using the Timeline Follow-Back procedure. Latent class mixture modeling identified trajectories based on maximum number of consecutive abstinent days per month, separately for alcohol and other drugs. RESULTS: Four alcohol trajectories were identified: high abstinence (53%), decreasing abstinence (10%), increasing abstinence (16%) and low abstinence (21%). The alcohol trajectories were distinguished by gender, age, readiness to change substance use and alcohol-related coping. To characterize changes in alcohol abstinence in relation to abstinence from other drugs, four other drug trajectories were identified: high (59%), decreasing (12%), increasing (14%) and low (15%) abstinence. Cross-classification of the alcohol and drug trajectories indicated a moderate level of concordance (kappa = 0.49). CONCLUSIONS: Multiple pathways of short-term change in alcohol and other drug use were identified. Although changes in abstinence from alcohol and other drug use tended to co-occur, exceptions were observed. Differences between alcohol trajectories in readiness to change substance use and use of substance coping suggest the potentially positive impact of targeted and effectively timed interventions that focus on motivational enhancement and on improving substance coping for certain adolescent subgroups.

Adolescent↗
PubMed2005

Adolescent-to-young adulthood heavy drinking trajectories and their prospective predictors.

OBJECTIVE: The purpose of this study was to investigate longitudinal trajectories of heavy drinking for males and females from adolescence to young adulthood, across the age span of 16-25 years, and to identify prospective predictors of the trajectory groups identified. METHOD: This study used semiparametric group-based mixture modeling to derive adolescent to young adult longitudinal trajectories of heavy drinking separately for 760 participants (430 females and 330 males) who have been participating in a long-term prospective study of risk factors for the development of heavy drinking and alcohol disorders. RESULTS: Four trajectory groups were identified for males and five for females; the trajectories indicated both continuity and change in heavy drinking across time for the trajectory groups identified. Major common prospective predictors for the high and very high heavy drinking trajectory groups supported the influences of values and beliefs (e.g., religious commitment), stressful life events and substance use. Additional predictors for males included lower academic functioning and task orientation, and for females, more frequent sexual behavior and general deviance. CONCLUSIONS: In this predominantly white, middle-class sample, we identified groups of frequent, heavy drinking teens during the middle-adolescent years. Our findings suggest that the frequency of heavy drinking behavior will further increase for some teens into their young adult years. The potential adverse consequences of heavy drinking among adolescents and young adults suggests that multitargeted, gender-specific, early interventions with these high-risk teens is important.

Adolescent↗
PubMed2007

Alcohol initiation experiences and family history of alcoholism as predictors of problem-drinking trajectories.

OBJECTIVE: The purpose of this study was to identify developmental trajectories of problem drinking from adolescence into young adulthood and to determine if alcohol use initiation experiences and family history of alcoholism, as well as their interactions, would predict trajectory group membership. METHOD: Five waves of data were collected from respondents who were 12 years old at the time of recruitment to the Rutgers Health and Human Development Project and followed until age 31 (n = 438). A standardized measure of problem drinking (Rutgers Alcohol Problem Index) was used to develop trajectories with growth-mixture modeling. Differences across groups in first- use experience (age of onset, pleasantness of the experience, and feeling intoxicated), a family history of alcoholism, and gender were analyzed with chi-square and analysis of variance tests, and logistic regression analyses were used to estimate the odds of group membership. RESULTS: Three trajectory groups of drinkers were identified: no or low problem (66.2%), adolescence-limited problem (ALP; 21.6%), and escalating problem (EP; 12.1%) drinkers. Age at drinking onset, feeling drunk during the first alcohol experience, and family history of alcoholism were associated with significantly greater odds of being in a problem trajectory group relative to the no or low problem trajectory. Early experiences did not differentiate the ALP and EP trajectories. None of the interactions was significantly associated with membership in any of the groups. CONCLUSIONS: The levels and patterns of problem drinking during early to mid-adolescence point to a need for secondary prevention efforts that target problematic users in addition to the current emphasis on primary prevention of alcohol consumption. Prevention-based research may benefit from special focus on the meaning and consequences of self-perception of drunkenness when alcohol is first used.

Adolescent↗
PubMed2001

Brain biopsy sampling by using prospective stereotaxis and a trajectory guide.

OBJECT: The authors describe their initial results obtained using a skull-mounted trajectory guide for intraoperative magnetic resonance (MR) imaging-guided brain biopsy sampling. The device was used in conjunction with a new methodology known as prospective stereotaxis for surgical trajectory alignment. METHODS: Between January 1999 and March 2000, 38 patients underwent 40 brain biopsy procedures in which prospective stereotaxis was performed with the trajectory guide in a short-bore 1.5-tesla MR imager. In most cases, orthogonal T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) images were used to determine the desired trajectory and align the device. The surgical trajectory was defined as a line connecting three points: the target, pivot, and alignment stem points. In all cases, surgical specimens were submitted for frozen section and pathological examination. Postoperative turbofluid-attenuated inversion-recovery and gradient-echo images were obtained to exclude the presence of hemorrhage. Trajectory determination and alignment was simple and efficient, requiring less than 5 minutes. Confirmatory HASTE images were obtained along the biopsy needle as it was being advanced or after reaching the target. All biopsy procedures yielded diagnostic tissue. One patient with a lesion near the motor strip experienced a transient hemiparesis of the hand related to passage of the biopsy needle, and another sustained a fatal postoperative myocardial infarction. No patient suffered a clinically significant or radiologically visible hemorrhage. CONCLUSIONS: In combination with prospective stereotaxis, the trajectory guide provided a safe and accurate way to perform brain biopsy procedures.

Adolescent↗