The posttraumatic stress disorder diagnosis in preschool- and elementary school-age children exposed to motor vehicle accidents

Objective: Increasingly, children are being diagnosed with psychiatric disorders, including preschool-age children. These diagnoses in young children raise questions pertaining to 1) how diagnostic algorithms for individual disorders should be modified for young age groups, 2) how psychopathology is best detected at an early stage, and 3) how to make use of multiple informants. The authors examined these issues in a prospective longitudinal assessment of preschool- and elementary school-age children who were exposed to a traumatic event. Method: Participants were 114 children (age range: 2-10 years) who had experienced a motor vehicle accident. Parents and older children (age range: 7-10 years) completed structured interviews 2-4 weeks (initial assessment) and 6 months (6-month follow-up) after the traumatic event. A recently proposed alternative symptom algorithm for diagnosing posttraumatic stress disorder (PTSD) was utilized and compared with the standard DSM-IV algorithms for diagnosing PTSD and acute stress disorder. Results: At the 2- to 4-week assessment, 11.5% of the children met conditions for a diagnosis of PTSD based on the alternative algorithm criteria per parent report, and 13.9% met criteria for this diagnosis at the 6-month follow-up. These percentages were much higher than those for DSM-IV diagnoses of acute stress disorder and PTSD. Among 7- to 10-year-old subjects, the use of combined parent- and child-reported symptoms to derive a diagnosis resulted in an increased number of children in this age group who were identified with psychiatric illness relative to the use of parent report alone. Agreement between parent and child on symptoms for 1) a diagnosis of PTSD based on the alternative algorithm criteria and 2) diagnoses of DSM-IV acute stress disorder and PTSD in this age group was poor. Among 2- to 6-year-old subjects, the alternative algorithm PTSD diagnosis per parent report was a more sensitive predictor of later onset psychopathology relative to a diagnosis of DSM-IV acute stress disorder or PTSD per parent report. However, among 7- to 10-year-old subjects, a combined symptom report (from both parent and child) was optimal in predicting posttraumatic psychopathology. Conclusions: These findings support the use of the proposed alternative algorithm for assessing PTSD in young children and suggest that the diagnosis of PTSD based on the alternative algorithm criteria is stable from the acute phase onward. When both parent- and child-reported symptoms are utilized for the assessment of PTSD among 7- to 10-year-old children, the alternative algorithm and DSM-IV criteria have broad comparable validity. However, in the absence of child-reported symptoms, the alternative algorithm criteria per parent report appears to be an optimal diagnostic measure of PTSD among children in this age group, relative to the standard DSM-IV algorithm for diagnosing the disorder

Maladaptive Cognitive Appraisals Mediate the Evolution of Posttraumatic Stress Reactions:A 6-Month Follow-Up of Child and Adolescent Assault and Motor Vehicle Accident Survivors

A prospective longitudinal follow-up study (n = 59) of child and adolescent survivors of physical assaults and motor vehicle accidents assessed whether cognitive processes predicted posttraumatic stress symptomatology (PTSS) at 6 months posttrauma in this age group. In particular, the study assessed whether maladaptive posttraumatic appraisals mediated the relationship between initial and later posttraumatic stress. Self-report measures of PTSS, maladaptive appraisals, and other cognitive processes, as well as structured interviews assessing for acute stress disorder and posttraumatic stress disorder (PTSD), were completed at 2-4 weeks and 6 months posttrauma. PTSS and PTSD at 6 months were associated with maladaptive appraisals and other cognitive processes but not demographic or objective trauma severity variables. Only maladaptive appraisals were found to associate with PTSS/PTSD after partialing out initial symptoms/diagnosis and to mediate between initial and later PTSS. It was argued that, on this basis, maladaptive appraisals are involved in the development and maintenance of PTSS over time, whereas other cognitive processes (e.g., subjective threat, memory processes) may have an effect only in the acute phase. The implications of this study for the treatment of PTSS in youths are discussed

Statistics of Lead Changes in Popularity-Driven Systems

We study statistical properties of the highest degree, or most popular, nodes in growing networks. We show that the number of lead changes increases logarithmically with network size N, independent of the details of the growth mechanism. The probability that the first node retains the lead approaches a finite constant for popularity-driven growth, and decays as N^{-phi}(ln N)^{-1/2}, with phi=0.08607..., for growth with no popularity bias.Comment: 4 pages, 4 figures, 2 column revtex format. Minor changes in response to referee comments. For publication in PR

Constant angular velocity of the wrist during the lifting of a sphere.

The primary objective of the experiments was to investigate the wrist motion of a person while they were carrying out a prehensile task from a clinical hand function test. A sixcamera movement system was used to observe the wrist motion of 10 participants. A very light sphere and a heavy sphere were used in the experiments to study any mass effects. While seated at a table, a participant moved a sphere over a small obstacle using their dominant hand. The participants were observed to move their wrist at a constant angular velocity. This phenomenon has not been reported previously. Theoretically, the muscles of the wrist provide an impulse of force at the start of the rotation while the forearm maintains a constant vertical force on a sphere. Light–heavy mean differences for the velocities, absolute velocities, angles and times taken showed no significant differences (p¼0.05)

Genealogies of rapidly adapting populations

The genetic diversity of a species is shaped by its recent evolutionary history and can be used to infer demographic events or selective sweeps. Most inference methods are based on the null hypothesis that natural selection is a weak or infrequent evolutionary force. However, many species, particularly pathogens, are under continuous pressure to adapt in response to changing environments. A statistical framework for inference from diversity data of such populations is currently lacking. Toward this goal, we explore the properties of genealogies in a model of continual adaptation in asexual populations. We show that lineages trace back to a small pool of highly fit ancestors, in which almost simultaneous coalescence of more than two lineages frequently occurs. While such multiple mergers are unlikely under the neutral coalescent, they create a unique genetic footprint in adapting populations. The site frequency spectrum of derived neutral alleles, for example, is non-monotonic and has a peak at high frequencies, whereas Tajima's D becomes more and more negative with increasing sample size. Since multiple merger coalescents emerge in many models of rapid adaptation, we argue that they should be considered as a null-model for adapting populations.Comment: to appear in PNA

Detailed investigation of a vaporising fuel spray. Part 1: Experimental investigation of time averaged spray

A laser tomographic light scattering technique provides rapid and accurate high resolution measurements of droplet sizes, concentrations, and vaporization. Measurements using a computer interfaced thermocouple are presented and it is found that the potential exists for separating gas and liquid temperature measurements and diagnosing local spray density by in situ analysis of the response characteristics of the thermocouple. The thermocouple technique provides a convenient means for measuring mean gas velocity in both hot and cold two phase flows. The experimental spray is axisymmetric and has carefully controlled initial and boundary conditions. The flow is designed to give relatively insignificant transfer of momentum and mass from spray to air flow. The effects of (1) size-dependent droplet dispersion by the turbulence, (2) the initial spatial segregation of droplet sizes during atomization, and (3) the interaction between droplets and coherent large eddies are diagnosed