Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-Ray Spectroscopy of Muonic Neon.

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high precision x-ray spectroscopy of the 5g-4f and 5f- 4d transitions (BSQED contribution of 2.4 and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the 5g_{9/2}- 4f_{7/2} transition energy to be 6297.08±0.04(stat)±0.13(syst) eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

Measurements of Strong-Interaction Effects in Kaonic-Helium Isotopes at Sub-eV Precision with X-Ray Microcalorimeters.

We have measured the 3d→2p transition x rays of kaonic ^{3}He and ^{4}He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be 6224.5±0.4(stat)±0.2(syst) eV and 6463.7±0.3(stat)±0.1(syst) eV, and widths to be 2.5±1.0(stat)±0.4(syst) eV and 1.0±0.6(stat)±0.3(stat) eV, for kaonic ^{3}He and ^{4}He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach and agree with calculations based on optical-potential models.

Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays.

We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic Kα and Kß x rays together with the hypersatellite K^{h}α x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K- and L-shell hole production and their temporal evolution on the 10-20 fs scale during the muon cascade process.

Factors Associated with Self-Injurious Behaviors in Children with Autism Spectrum Disorder: Findings from Two Large National Samples.

In this study, we explored potential associations among self-injurious behaviors (SIB) and a diverse group of protective and risk factors in children with autism spectrum disorder from two databases: Autism and Developmental Disabilities Monitoring (ADDM) Network and the Autism Speaks-Autism Treatment Network (AS-ATN). The presence of SIB was determined from children's records in ADDM and a parent questionnaire in AS-ATN. We used multiple imputation to account for missing data and a non-linear mixed model with site as a random effect to test for associations. Despite differences between the two databases, similar associations were found; SIB were associated with developmental, behavioral, and somatic factors. Implications of these findings are discussed in relation to possible etiology, future longitudinal studies, and clinical practice.

A reliable and efficient method for cerebral ventricular volumetry in pediatric neuroimaging.

OBJECTIVES: Cerebral ventricular volume has the potential to become an important parameter in quantitative neurological diagnosis. However, no accepted methodology for routine clinical use exists to date. We sought a robust, reproducible, and fast technique to evaluate cerebral ventricular volume in young children. METHODS: We describe a novel volumetric methodology to segment and visualize intracerebral fluid spaces and to quantify ventricular volumes. The method is based on broadly available T1 weighted volumetric magnetic resonance (MR) imaging, an interactive watershed transform, and a fully automated histogram analysis. We evaluated this volumetric methodology with 34 clinical volumetric MR datasets from non-sedated children (age 6-7 y) with a history of prematurity and low birth weight (< or = 1500 g) obtained during a prospective study. RESULTS: The methodology, with adaptation for small ventricular size, was capable of evaluating all 34 of the pediatric datasets for cerebral ventricular volume. The method was a) robust for normal and pathological anatomy, b) reproducible, c) fast with less than five minutes for image analysis, and d) equally applicable to children and adults. CONCLUSIONS: Clinical brain ventricular volume calculations in non-sedated children can be performed using routine MR imaging besides efficient three-dimensional segmentation and histogram analysis with results that are robust and reproducible.

Prenatal and postnatal risk factors for mental retardation among children in Bangladesh.

This study evaluated the contribution of prenatal, perinatal, neonatal, and postnatal factors to the prevalence of cognitive disabilities among children aged 2-9 years in Bangladesh. A two-phase survey was implemented in 1987-1988 in which 10,299 children were screened for disability. In multivariate analyses, significant independent predictors of serious mental retardation in rural and urban areas included maternal goiter (rural odds ratio (OR) = 5.14, 95% confidence interval (CI): 1.23, 21.57; urban OR = 4.82, 95% CI: 2.73, 8.50) and postnatal brain infections (rural OR = 29.24, 95% CI: 7.17, 119.18; urban OR = 13.65, 95% CI: 4.69, 39.76). In rural areas, consanguinity (OR = 15.13, 95% CI: 3.08, 74.30) and landless agriculture (OR = 6.02, 95% CI: 1.16, 31.19) were also independently associated with the prevalence of serious mental retardation. In both rural and urban areas, independent risk factors for mild cognitive disabilities included maternal illiteracy (OR = 2.48, 95% CI: 0.86, 7.12), landlessness (OR = 4.27, 95% CI: 1.77, 10.29), maternal history of pregnancy loss (OR = 2.61, 95% CI: 0.95, 7.12), and small for gestational age at birth (OR = 3.86, 95% CI: 1.56, 9.55). Interventions likely to have the greatest impact on preventing cognitive disabilities among children in Bangladesh include expansion of existing iodine supplementation, maternal literacy, and poverty alleviation programs as well as prevention of intracranial infections and their consequences. Further population-based studies are needed to confirm and understand the association between consanguinity and serious cognitive disability.

Epidemiology and prevention of traffic injuries to urban children and adolescents.

OBJECTIVES: To describe the incidence of severe traffic injuries before and after implementation of a comprehensive, hospital-initiated injury prevention program aimed at the prevention of traffic injuries to school-aged children in an urban community. MATERIALS AND METHODS: Hospital discharge and death certificate data on severe pediatric injuries (ie, injuries resulting in hospital admission and/or death to persons age <17 years) in northern Manhattan over a 13-year period (1983-1995) were linked to census counts to compute incidence. Rate ratios with 95% CIs, both unadjusted and adjusted for annual trends, were calculated to test for a change in injury incidence after implementation of the Harlem Hospital Injury Prevention Program. This program was initiated in the fall of 1988 and continued throughout the study period. It included 1) school and community based traffic safety education implemented in classroom settings in a simulated traffic environment, Safety City, and via theatrical performances in community settings; 2) construction of new playgrounds as well as improvement of existing playgrounds and parks to provide expanded off-street play areas for children; 3) bicycle safety clinics and helmet distribution; and 4) a range of supervised recreational and artistic activities for children in the community. PRIMARY RESULTS: Traffic injuries were a leading cause of severe childhood injury in this population, accounting for nearly 16% of the injuries, second only to falls (24%). During the preintervention period (1983-1988), severe traffic injuries occurred at a rate of 147.2/100 000 children <17 years per year. Slightly <2% of these injuries were fatal. Pedestrian injuries accounted for two thirds of all severe traffic injuries in the population. Among school-aged children, average annual rates (per 100 000) of severe injuries before the intervention were 127.2 for pedestrian, 37.4 for bicyclist, and 25.5 for motor vehicle occupant injuries. Peak incidence of pedestrian and bicyclist injuries occurred during the summer months and afternoon hours, whereas motor vehicle occupant injuries showed little seasonal variation and were more common during evening and night-time hours. Age-specific rates showed peak incidence of pedestrian injuries among 6- to 10-year-old children, of bicyclist injuries among 9- to 15-year-old children, and of motor vehicle occupant injuries among adolescents between the ages of 12 and 16 years. The peak age for all traffic injuries combined was 15 years, an age at which nearly 3 of every 1000 children each year in this population sustained a severe traffic injury. Among children hospitalized for traffic injuries during the preintervention period, 6.3% sustained major head trauma (including concussion with loss of consciousness for >/=1 hour, cerebral laceration and/or cerebral hemorrhage), and 36.9% sustained minor head trauma (skull fracture and/or concussion with no loss of consciousness >/=1 hour and no major head injury). The percentage of injured children with major and minor head trauma was higher among those injured in traffic than among those injured by all other means (43.2% vs 14.2%, respectively; chi2 = 336; degrees of freedom = 1). The percentages of children sustaining head trauma were 45.4% of those who were injured as pedestrians, 40.2% of those who were injured as bicyclists, and 38.9% of those who were injured as motor vehicle occupants. During the intervention period, the average incidence of traffic injuries among school aged children declined by 36% relative to the preintervention period (rate ratio:.64; 95% CI:.58,.72). After adjusting for annual trends in incidence, pedestrian injuries declined during the intervention period among school aged children by 45% (adjusted rate ratio:.55; 95% CI:.38,.79). No comparable reduction occurred in nontargeted injuries among school-aged children (adjusted rate ratio:.89; 95% CI:.72, 1.09) or in traffic injuries among younger children who

The epidemiology of urban pediatric neurological trauma: evaluation of, and implications for, injury prevention programs.

OBJECTIVE: To describe the incidence and causes of pediatric head, spinal cord, and peripheral nerve injuries in an urban setting and to assess the implications of these data for injury prevention programs. METHODS: Pediatric deaths and hospital admissions secondary to neurological trauma included in the Northern Manhattan Injury Surveillance System from 1983 to 1992 were linked to census counts to compute incidence rates. Rates before the implementation of a nonspecific injury prevention program were compared with rates after the implementation, and rates for the target population were compared to rates for the control population. Rates were analyzed on the basis of the cause of injury as well as the age, gender, and neighborhood income level of the injured. RESULTS: The incidence of neurological injuries resulting in hospitalization or death was 155 incidents per 100,000 population per year; the mortality rate was 6 people per 100,000 population per year. Neurological injuries represented 18% of all pediatric injuries and accounted for 23% of all traumatic deaths. Spinal cord and peripheral nerve injuries were relatively rare (5%) compared to head injuries (95%). Minor head injuries, including isolated cranial fractures, minor concussions (<1 h loss of consciousness), and unspecified minor head injuries, accounted for the majority of neurological injuries (76%), whereas severe head injuries, including severe concussion (>1 h loss of consciousness), cerebral laceration/contusion, intracerebral hemorrhage, and unspecified major injuries, were less common (18% of all neurological injuries). Boys were more often affected than girls at every age, and this preference increased with age. Children younger than 1 year showed the highest incidence of both major and minor injuries. One- to 4-year olds showed the lowest rates, with steady increases thereafter. Traffic accidents and falls were the leading causes (38 and 34%, respectively), and assaults were the next leading causes (12%). Among children admitted to surveillance system hospitals, falls were most common in children younger than 4 years, pedestrian motor vehicle accidents were most common in late childhood, and assaults were most common in early adolescence. CASE: fatality rates were 5 to 7% for all age groups except 5- to 12-year-olds, for whom the case:fatality rate was 1.9%. Residence in a low-income neighborhood was associated with an increased risk of injury (rate ratio, 1.71; confidence interval, 95%, 1.54, 1.89). The average hospitalization cost per injury was $8502. Medicaid (54%) and other government sources (5%) covered the majority of expenses, including indirect reimbursement of usually uncollected self-pay billing (19%). Although injury incidence rates fell in both the control and intervention cohorts during implementation of a nonspecific injury prevention program, targeted age and population groups demonstrated greater relative reductions in injuries than nontargeted ones, suggesting a positive effect. CONCLUSIONS: Deaths and hospital admissions secondary to pediatric neurological trauma represent a significant public health problem, with the majority of the direct cost being born by government agencies. Future efforts to prevent neurological trauma in children who live in inner cities should focus on families with low incomes and provide novel education programs regarding infant abuse, infant neglect, and infant injury avoidance. Age-appropriate school-based programs should also be developed to address traffic safety and conflict resolution.

Prevalence and correlates of mental retardation among children in Karachi, Pakistan.

This paper reports estimates of the prevalence of mental retardation and associated factors based on a population survey of 2- to 9-year-old children in Greater Karachi, Pakistan. A two-phase survey was implemented during the years 1988-1989. In the first phase, a cluster sample of 6,365 children (5,748 from urban areas and 617 from rural areas) was screened for disabilities using a parental report known as the Ten Questions instrument. In the second phase, all children with positive screening results and a 10% sample of those with negative results were referred for structured medical and psychological assessments. Estimates of the prevalence of mental retardation were 19.0/1,000 children (95% confidence interval (CI) 13.5-24.4) for serious retardation and 65.3/1,000 children (95% CI 48.9-81.8) for mild retardation. Both estimates were considerably higher than respective prevalence estimates obtained in industrialized countries and in selected less developed countries. In this population, lack of maternal education was strongly associated with the prevalence of both serious (odds ratio = 3.26, 95% CI 1.26-8.43) and mild (odds ratio = 3.08, 95% CI 1.85-5.14) retardation. Other factors that were independently associated with mental retardation in Karachi included histories of perinatal difficulties, neonatal infections, postnatal brain infections, and traumatic brain injury, as well as current malnourishment. Further research is needed to assess the contribution of consanguineous marriage, improvements in child survival, and other factors to the unusually high prevalence of mental retardation in this population.

Validity of hospital discharge data regarding intentionality of fatal pediatric injuries.

This study of hospitalized fatal injuries to children in New York City (1991-1992) compares the classification of injury intention on hospital discharge data with that on death certificates in 302 injuries for which records could be linked. Using death certificates as the criterion, the sensitivity of hospital data for identifying intentional injuries ranged from 0.50 for children under age 5 years confidence interval (CI) = 0.27-0.73] to 0.85 for adolescents (95% CI = 0.80-0.90), and from 0.75 for white children (95% CI = 0.65-0.83) to 0.89 for nonwhite children (95% CI = 0.82-0.93). Hospital discharge data for this population appear to understate both the incidence and the proportion of fatal injuries due to intentional causes, particularly those occurring to very young children and to white children.

Epidemiology and prevention of severe assault and gun injuries to children in an urban community.

OBJECTIVES: To describe the epidemiology of severe assault and gun injuries to children in an urban population and consider the impact of a comprehensive injury prevention program. MATERIALS AND METHODS: Pediatric injury deaths and hospital admissions for Northern Manhattan (1983-1992) were linked to census counts to compute incidence. Poisson regression was used to compare trends in incidence of assault and gun injuries before and during a community-wide pediatric injury prevention program in Central Harlem. MAIN RESULTS: The incidence of severe nonfatal assault injury was 60.94/100,000/year, 10 times the fatality rate. The incidence of all gun injuries was 31.13. In adolescence, guns were the leading cause of both fatal and severe nonfatal assault injury, and were the most lethal method of assault (case-fatality = 18.5% for gun vs. 1.2% for all non-gun assault injury). Rates of assault and gun injuries declined by nearly 50% in the intervention community, while they increased in a neighboring community. CONCLUSIONS: Comprehensive interventions may be effective in curbing the incidence of severe assault injuries to urban youth. Further controlled evaluations are needed to confirm the effectiveness of programs such as this and to better understand the prevention of violent injuries.

The ten questions screen for childhood disabilities: its uses and limitations in Pakistan.

OBJECTIVE: To assess the accuracy of the ten questions screen as a measure of childhood disability for epidemiologic studies in populations lacking resources for professional assessment of children's development and functioning. DESIGN: Household survey and screening of children in phase one followed by clinical assessments in phase two. SETTING: Karachi, Pakistan. PARTICIPANTS: A cluster sample of 6365 children, aged 2 to 9 years, screened using the ten questions and a subsample referred for clinical assessments. MAIN RESULTS: Although the sensitivity of the ten questions as a global screen for serious cognitive, motor, and seizure disabilities is high (84-100%), its sensitivity for identifying and distinguishing specific types of disability and for detecting vision, hearing, and mild disabilities, overall, is limited (generally < 80% and as low as 4% for mild vision disability). The predictive value of a positive screening result is also limited-using the ten questions in surveys without clinical confirmation results in overestimation of the prevalence of serious disability by more than 300%. CONCLUSIONS: The ten questions screen is not an assessment tool. Its utility lies in its ability to screen or select a fraction of the population at high risk for serious disability. As a screening tool, it allows scarce diagnostic and other professional resources to be efficiently directed toward those at high risk.

Evaluating a ten questions screen for childhood disability: reliability and internal structure in different cultures.

This paper uses five strategies to evaluate the reliability and other measurement qualities of the Ten Questions screen for childhood disability. The screen was administered for 22,125 children, aged 2-9 years, in Bangladesh, Jamaica and Pakistan. The test-retest approach involving small sub-samples was useful for assessing reliability of overall screening results, but not of individual items with low prevalence. Alternative strategies focus on the internal consistency and structure of the screen as well as item analyses. They provide evidence of similar and comparable qualities of measurement in the three culturally divergent populations, indicating that the screen is likely to produce comparable data across cultures. One of the questions, however, correlates with the other questions differently in Jamaica, where it appears to "over-identify" children as seriously disabled. The methods and findings reported here have general applications for the design and evaluation of questionnaires for epidemiologic research, particularly when the goal is to gather comparable data in geographically and culturally diverse settings.

Use of Poisson regression and time series analysis for detecting changes over time in rates of child injury following a prevention program.

The use of two statistical methods to quantify time trends (Poisson regression and time series analysis) is illustrated in analyses of changes in child injury incidence after implementation of a community-based injury prevention program in Central Harlem, New York City. The two analytical methods are used to quantify changes in the rate of injury following the program, while taking into account the underlying annual and seasonal trends. Rates of severe injury during the period from 1983 to 1991 among children under the age of 17 years living in Central Harlem and in the neighboring community of Washington Heights are analyzed. The two methods provide similar point estimates of the effect of the intervention and have a good fit to the data. Although time series analysis has been promoted as the method of choice in analysis of sequential observations over long periods of time, this illustration suggests that Poisson regression is an attractive and viable alternative. Poisson regression provides a versatile analytical method for quantifying the time trends of relatively rare discrete outcomes, such as severe injuries, and provides a useful tool for epidemiologists involved with program evaluation.

Measures of socioeconomic status for child health research: comparative results from Bangladesh and Pakistan.

This paper examines the reliability and validity of several hypothesized indicators of socioeconomic status for use in epidemiologic research, particularly in studies of child health in the less developed world. Population-based surveys of child health and disability were completed in Bangladesh and Pakistan using standard questionnaires designed to measure four domains of household socioeconomic status: wealth, housing, parental education and occupation. Test-retest data indicate moderate to excellent reliability of most of the socioeconomic indicators in both countries. Loadings from factor analyses of the survey data provide further evidence of the reliability of the data, and confirm that the questionnaire measures housing and wealth as distinct domains in both countries. Parental education and occupation are correlated with housing and/or wealth in these data sets. Bivariate logistic regression analyses show that, although 11 of 12 dichotomous indicators of low socioeconomic status constructed from the data are predictive of child death in at least one of the four sub-populations studied (rural and urban Bangladesh, and rural and urban areas of Karachi, Pakistan), no single indicator is predictive of child death in all four sub-populations. These along with multivariate results demonstrate the importance of including multiple measures of distinct domains if the research aims include investigation and/or control of the effects of socioeconomic status on health in diverse populations.

Validity of the ten questions screened for childhood disability: results from population-based studies in Bangladesh, Jamaica, and Pakistan.

An international study to validate the Ten Questions screen for serious childhood disability was undertaken in communities in Bangladesh, Jamaica, and Pakistan, where community workers screened more than 22,000 children ages 2-9 years. All children who screened positive, as well as random samples of those who screened negative, were referred for clinical evaluations. Applying comparable diagnostic criteria, the sensitivity of the screen for serious cognitive, motor, and seizure disabilities is acceptable (80-100%) in all three populations, whereas the positive predictive values range from 3 to 15%. These results confirm the usefulness of the Ten Questions as a low-cost and rapid screen for these disabilities, although not for vision and hearing disabilities, in populations where few affected children have previously been identified and treated. They also show that the value of the Ten Questions for identifying disability in underserved populations is limited to that of a screen; more thorough evaluations of children screened positive are necessary to distinguish true- from false-positive results and to identify the nature of the disability if present.

The impact of the Safe Kids/Healthy Neighborhoods Injury Prevention Program in Harlem, 1988 through 1991.

OBJECTIVES: This study evaluated the effectiveness of a community coalition to prevent severe injuries to children in Central Harlem, New York, NY. It was hypothesized that injury incidence rates would decline during the intervention (1989 through 1991) relative to preintervention years (1983 through 1988); that the decline would be greatest for the targeted age group (5 through 16 years) and targeted injury causes (traffic accidents, assaults, firearms, outdoor falls); and that the decline would occur in the intervention community rather than a control community. METHODS: Surveillance of injuries that result in hospitalization and/or death among children in the two communities has been under way since 1983. Data from this surveillance were used to test whether the incidence of severe injury declined during the intervention; other temporal variations were controlled by Poisson regression. RESULTS: The incidence of injury among school-aged children in central Harlem declined during the intervention. The decline was specific to the targeted age group and targeted causes. A nonspecific decline also occurred in the control community. CONCLUSIONS: The declining incidence rate in Central Harlem is consistent with a favorable program effect, but additional investigation of possible secular trend or spillover effects is needed.

Low-income neighborhoods and the risk of severe pediatric injury: a small-area analysis in northern Manhattan.

OBJECTIVES: The purpose of this study was to investigate the relationship between socioeconomic disadvantage and the incidence of severe childhood injury. METHODS: Small-area analysis was used to examine socioeconomic risk factors for pediatric injury resulting in hospitalization or death in Northern Manhattan, New York, NY, during a 9-year period (1983 through 1991). RESULTS: The average annual incidence of all causes of severe pediatric injury was 72.5 per 10,000 children; the case-fatality rate was 2.6%. Census tract proportions of low-income households, single-parent families, non-high school graduates, and unemployment were significant predictors of risk for both unintentional and intentional injury. Among the socioeconomic factors considered, low income was the single most important predictor of all injuries; other socioeconomic variables were not independent contributors once income was included in the model. Compared with children living in areas with few low-income households, children in areas with predominantly low-income households were more than twice as likely to receive injuries from all causes and four and one half times as likely to receive assault injuries. The effect of neighborhood income disparities on injury risk persisted after race was controlled. CONCLUSIONS: These results illuminate the impact of socioeconomic disparities on child health and point to the need for injury prevention efforts targeting low-income neighborhoods.