With increasing evidence of adverse health effects associated with particulate matter (PM), the exposure impact of natural sources, such as forest fires, has substantial public health relevance. In ...addition to the threat to nearby communities, pollutants released from forest fires can travel thousands of kilometers to heavily populated urban areas. There was a dramatic increase in forest fire activity in the province of Quebec, Canada, during July 2002. The transport of PM released from these forest fires was examined using a combination of a moderate-resolution imaging spectroradiometer satellite image, back-trajectories using a hybrid single-particle Lagrangian integrated trajectory, and local light detection and ranging measurements. Time- and size-resolved PM was evaluated at three ambient and four indoor measurement sites using a combination of direct reading instruments (laser, time-of-flight aerosol spectrometer, nephelometer, and an oscillating microbalance). The transport and monitoring results consistently identified a forest fire related PM episode in Baltimore that occurred the first weekend of July 2002 and resulted in as much as a 30-fold increase in ambient fine PM. On the basis of tapered element oscillating microbalance measurements, the 24 h PM2.5 concentration reached 86 μg/m3 on July 7, 2002, exceeding the 24 h national ambient air quality standard. The episode was primarily comprised of particles less than 2.5 μm in aerodynamic diameter, highlighting the preferential transport of the fraction of PM that is of greatest health concern. Penetration of the ambient episode indoors was efficient (median indoor-to-outdoor ratio 0.91) such that the high ambient levels were similarly experienced indoors. These results are significant in demonstrating the impact of a natural source thousands of kilometers away on ambient levels of and potential exposures to air pollution within an urban center. This research highlights the significance of transboundary air pollution and the need for studies that assess the public health impacts associated with such sources and transport processes.
Body dissatisfaction is associated with a range of adverse outcomes, including impaired psychological health, low physical activity and disordered eating. This longitudinal study used the Factors ...Influencing Transitions in Girls' Active Leisure and Sport (FITGALS) dataset to examine trends in body image of adolescent females. Specifically, the study examined satisfaction with body size, physical appearance and dieting behaviour for two cohorts at transitional life phases in two geographic regions longitudinally over a 3-year period.
A sample of 732 adolescent females in Grade 7 (n = 489, 66.8 %) and Grade 11 (n = 243, 33.2 %) at randomly selected Australian metropolitan and non-metropolitan secondary schools responded to a questionnaire in three successive years from 2008 to 2010. Participants reported perceptions about their body size and physical appearance and whether they were, or ought to be, on a diet. The data were analysed using a series of longitudinal logistic regression models.
Dieting and dissatisfaction with body size significantly increased over time and more so for older than younger girls. Region significantly moderated the effect of grade level regarding dissatisfaction with body size but not dieting. In non-metropolitan regions, those in the younger cohort were significantly more likely to be dissatisfied with their body size than the older cohort; whereas in metropolitan regions, those in the older cohort were significantly more likely to be dissatisfied with their body size than the younger cohort. Adolescent female's perceptions of their appearance were unchanged over time, region and grade level.
Differences across time, region and grade level were found among adolescent females on body size and dieting behaviour, but not physical appearance. Adolescent females experience early and increasing body size dissatisfaction and dieting as they age, but stable perceptions of physical appearance. Age and geographic region are important considerations for the timing and targeting of interventions to address body image concerns. Further investigation of regional differences in body image perceptions and factors that affect these is warranted. The findings of this study highlight the ongoing need for strategies during adolescence to promote a healthy appreciation of body size and appearance.
A novel water-soluble macromonomer based on octavinyl silsesquioxane has been synthesized and contains vinyl-terminated PEG 400 in each of the eight arms to promote water solubility. The macromonomer ...was characterized by NMR and FTIR and its aqueous solution properties examined. In water it exhibits an LCST with a cloud point at 23 °C for a 10 wt % aqueous solution. It is surface active with a CMC of 1.5 × 10–5 M in water and in 20:80 v/v acetone/water the CMC is 7.1 × 10–5 M, and TEM images showed spherical 22 nm aggregates in aqueous solution above the CMC. The macromonomer was copolymerized in a 20:80 v/v acetone/water mixture with a vinyl-terminated, triblock copolymer of lactide-PEG-lactide to form a library of cross-linked hydrogels that were designed for use as scaffolds for alveolar bone repair. The cross-linked copolymer networks were shown to contain a range of nm-μm sized pores and their swelling properties in water and PBS at pH 7.4 were examined. At pH 7.4 the hydrogel networks undergo a slow hydrolysis with the release of principally PEG and lactic acid fragments. The hydrogels were shown to be noncytotoxic toward fibroblast cultures at pH 7.4, both initially (days 1–5) and after significant hydrolysis had taken place (days 23–28).
Different MRA techniques used to evaluate spinal dural arteriovenous fistulas offer unique advantages and limitations with regards to temporal and spatial resolution. The purpose of this study was to ...compare the efficacy and interobserver agreement of 2 commonly used contrast-enhanced spinal MRA techniques, multiphase time-resolved MRA and single-phase first-pass MRA, in assessment of spinal dural arteriovenous fistulas.
Retrospective review of 15 time-resolved and 31 first-pass MRA studies in patients with clinical suspicion of spinal dural arteriovenous fistula was performed by 2 independent, blinded observers. DSA was used as the reference standard to compare the diagnostic performance of the 2 techniques.
There were 10 cases of spinal dural arteriovenous fistula in the time-resolved MRA group and 20 in the first-pass MRA group. Time-resolved MRA detected spinal dural arteriovenous fistulas with sensitivity and specificity of 100% and 80%, respectively, with 100% correct-level localization rate. First-pass MRA detected spinal dural arteriovenous fistulas with sensitivity and specificity of 100% and 82%, respectively, with 87% correct-level localization rate. Interobserver agreement for localization was excellent for both techniques; however, it was higher for time-resolved MRA. In 5 cases, the site of fistula was not included in the FOV, but a prominent intradural radicular vein was observed at the edge of the FOV.
Multiphase time-resolved MRA and single-phase first-pass MRA were comparable in diagnosis and localization of spinal dural arteriovenous fistulas and demonstrated excellent interobserver agreement, though there were more instances of ambiguity in fistula localization on first-pass MRA.
Spinal epidural AVFs are rare spinal vascular malformations. When there is associated intradural venous reflux, they may mimic the more common spinal dural AVFs. Correct diagnosis and localization ...before conventional angiography is beneficial to facilitate treatment. We hypothesize that first-pass contrast-enhanced MRA can diagnose and localize spinal epidural AVFs with intradural venous reflux and distinguish them from other spinal AVFs.
Forty-two consecutive patients with a clinical and/or radiologic suspicion of spinal AVF underwent MR imaging, first-pass contrast-enhanced MRA, and DSA at a single institute (2000-2015). MR imaging/MRA and DSA studies were reviewed by 2 independent blinded observers. DSA was used as the reference standard.
On MRA, all 7 spinal epidural AVFs with intradural venous reflux were correctly diagnosed and localized with no interobserver disagreement. The key diagnostic feature was arterialized filling of an epidural venous pouch with a refluxing radicular vein arising from the arterialized epidural venous system.
First-pass contrast-enhanced MRA is a reliable and useful technique for the initial diagnosis and localization of spinal epidural AVFs with intradural venous reflux and can distinguish these lesions from other spinal AVFs.
Purpose:
Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental ...demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative “scattering power” rather than “stopping power” is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons.
Methods:
A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed.
Results:
Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed.
Conclusions:
Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.
Catheter angiography is typically used for follow-up of treated spinal AVFs. The purpose of this study was to determine the diagnostic performance and utility of first-pass contrast-enhanced MRA in ...the posttreatment evaluation of spinal AVFs compared with DSA.
A retrospective review was performed of all patients at our tertiary referral hospital (from January 2000 to April 2015) who underwent spine MR imaging, first-pass contrast-enhanced MRA, and DSA after surgical and/or endovascular treatment of a spinal AVF. Presence of recurrent or residual fistula on MRA, including vertebral level of the recurrent/residual fistula, was evaluated by 2 experienced neuroradiologists blinded to DSA findings. Posttreatment conventional MR imaging findings were also evaluated, including presence of intramedullary T2 hyperintensity, perimedullary serpentine flow voids, and cord enhancement. The performance of MRA and MR imaging findings for diagnosis of recurrent/residual fistula was determined by using DSA as the criterion standard.
In total, 28 posttreatment paired MR imaging/MRA and DSA studies were evaluated in 22 patients with prior spinal AVF and 1 patient with intracranial AVF with prior cervical perimedullary venous drainage. Six image sets of 5 patients demonstrated recurrent/residual disease at DSA. MRA correctly identified all cases with recurrent/residual disease with 1 false-positive (sensitivity, 100%; specificity 95%; P < .001), with correct localization in all cases without interobserver disagreement. Conventional MR imaging parameters were not significantly associated with recurrent/residual spinal AVF.
First-pass MRA demonstrates high sensitivity and specificity for identifying recurrent/residual spinal AVFs and may potentially substitute for DSA in the posttreatment follow-up of patients with spinal AVFs.
Cerebral blood flow (CBF) abnormalities are previously demonstrated in white matter disease. A gradation of change may exist between patients with mild and more severe white matter disease. An ...association between blood brain barrier dysfunction, increasing age and white matter disease is also suggested. The purpose of this study was to quantify and correlate white matter disease severity and CT perfusion (CTP)-derived CBF and to determine whether permeability surface abnormality increases with white matter disease severity.
One hundred twenty patients with strokelike symptoms underwent CTP and MR imaging. Of these, 35 patients (15 women, 20 men; age, 66 +/- 15.7 years) with rapidly resolving symptoms and normal imaging characteristics consistent with transient ischemic attack were retrospectively reviewed and constituted the study cohort. Two blinded neurologists rated white matter severity, assigning age-related white matter change (ARWMC) scores. Patients were dichotomized a priori into mild and moderate-to-severe. CBF, cerebral blood volume (CBV), mean transit time (MTT), and permeability surface product maps were calculated for periventricular and subcortical white matter regions and average white and gray matter. Associations with white matter severity were tested by uni- and multivariate logistic regression analyses. Receiver operating characteristic analysis was performed.
White matter disease was mild in 26 patients and moderate-to-severe in 9. Age was associated with increased likelihood of having moderate-to-severe white matter disease (P = .02). ARWMC correlated with subcortical (r = -0.50, P < .001) and average CBF (r = -0.55, P < .001). White matter severity was associated with subcortical (P = .03) and average (P = .03) white matter CBF, with a trend toward periventricular white matter CBF (P = .05). Uni- and multivariate analysis controlling for the confounding effect of age demonstrated significant association between white matter severity and subcortical (P = .032) white matter CBF. Area under the curve was 0.82. No permeability surface abnormality was found.
CTP-derived subcortical white matter CBF is independently associated with white matter disease severity.
This paper considers the evolution of attempts to control and manage air pollution, principally but not exclusively focussing upon the challenge of managing air pollution in urban environments. The ...development and implementation of a range of air pollution control measures are considered. Initially the measures implemented primarily addressed point sources, a small number of fuel types and a limited number of pollutants. The adequacy of such a source-control approach is assessed within the context of a changing and challenging air pollution climate. An assessment of air quality management in the United Kingdom over a 50-year timeframe exemplifies the range of issues and challenges in contemporary air quality management. The need for new approaches is explored and the development and implementation of an effects-based, risk management system for air quality regulation is evaluated.
Background. The purposes of the current study were (a) to determine the test–retest reliability of a single-session isokinetic and isometric strength testing protocol in older healthy men, and (b) to ...compare the outcomes of the reliability measures derived from averaged torque scores with those derived from a single peak torque score. Methods. In 19 men (mean age, 72 ± 5 years), both lower limbs were assessed independently on 2 separate test days using the Biodex System 3 dynamometer. After completing a 5-minute warm-up, each man performed three submaximal knee extensions followed by five maximal contractions at 90°/s (CON), 0°/s (ISO), and −90°/s (ECC). Average (best 3 of 5) and peak CON, ISO, and ECC torque, and CON work and CON power were determined. Peak CON work and CON power were recorded from the highest peak torque concentric contraction (HPTCC). Results. Intraclass correlation coefficients ranging from 0.84 to 0.94 were found to have good reliability. The typical error as a coefficient of variation ranged from 8% to 10% for averaged measures and from 8% to 17% for peak torque and HPTCC. The ratio limits of agreement for average and peak CON, ISO, and ECC torque ranged from 23% to 33% and from 40% to 54% for average CON and HPTCC work and power. Conclusions. The test–retest reliability of a single-session isokinetic and isometric strength testing protocol in this group of older healthy men displayed good relative reliability (intraclass correlation coefficient > 0.84); however, because the typical error as a coefficient of variation and ratio limits of agreement (absolute reliability) were large, single-session testing is not recommended.
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