Receding and disparity cues aid relaxation of accommodation

Purpose. Accommodation can mask hyperopia and reduce the accuracy of non-cycloplegic refraction. It is, therefore, important to minimize accommodation to obtain a measure of hyperopia as accurate as possible. To characterize the parameters required to measure the maximally hyperopic error using photorefraction, we used different target types and distances to determine which target was most likely to maximally relax accommodation and thus more accurately detect hyperopia in an individual. Methods. A PlusoptiX SO4 infra-red photorefractor was mounted in a remote haploscope which presented the targets. All participants were tested with targets at four fixation distances between 0.3 and 2 m containing all combinations of blur, disparity, and proximity/looming cues. Thirty-eight infants (6 to 44 weeks) were studied longitudinally, and 104 children [4 to 15 years (mean 6.4)] and 85 adults, with a range of refractive errors and binocular vision status, were tested once. Cycloplegic refraction data were available for a sub-set of 59 participants spread across the age range. Results. The maximally hyperopic refraction (MHR) found at any time in the session was most frequently found when fixating the most distant targets and those containing disparity and dynamic proximity/looming cues. Presence or absence of blur was less significant, and targets in which only single cues to depth were present were also less likely to produce MHR. MHR correlated closely with cycloplegic refraction (r = 0.93, mean difference 0.07 D, p = n.s., 95% confidence interval +/-<0.25 D) after correction by a calibration factor. Conclusions. Maximum relaxation of accommodation occurred for binocular targets receding into the distance. Proximal and disparity cues aid relaxation of accommodation to a greater extent than blur, and thus non-cycloplegic refraction targets should incorporate these cues. This is especially important in screening contexts with a brief opportunity to test for significant hyperopia. MHR in our laboratory was found to be a reliable estimation of cycloplegic refraction. (Optom Vis Sci 2009;86:1276-1286

Politics and the media : the stormy year before the calm?

Politics and the media : the stormy year before the calm

FGF/heparin differentially regulates Schwann cell and olfactory ensheathing cell interactions with astrocytes: a role in astrocytosis

After injury, the CNS undergoes an astrocyte stress response characterized by reactive astrocytosis/proliferation, boundary formation, and increased glial fibrillary acidic protein (GFAP) and chondroitin sulfate proteoglycan (CSPG) expression. Previously, we showed that in vitro astrocytes exhibit this stress response when in contact with Schwann cells but not olfactory ensheathing cells (OECs). In this study, we confirm this finding in vivo by demonstrating that astrocytes mingle with OECs but not Schwann cells after injection into normal spinal cord. We show that Schwann cell-conditioned media (SCM) induces proliferation in monocultures of astrocytes and increases CSPG expression in a fibroblast growth factor receptor 1 (FGFR1)-independent manner. However, SCM added to OEC/astrocyte cocultures induces reactive astrocytosis and boundary formation, which, although sensitive to FGFR1 inhibition, was not induced by FGF2 alone. Addition of heparin to OEC/astrocyte cultures induces boundary formation, whereas heparinase or chlorate treatment of Schwann cell/astrocyte cultures reduces it, suggesting that heparan sulfate proteoglycans (HSPGs) are modulating this activity. In vivo, FGF2 and FGFR1 immunoreactivity was increased over grafted OECs and Schwann cells compared with the surrounding tissue, and HSPG immunoreactivity is increased over reactive astrocytes bordering the Schwann cell graft. These data suggest that components of the astrocyte stress response, including boundary formation, astrocyte hypertrophy, and GFAP expression, are mediated by an FGF family member, whereas proliferation and CSPG expression are not. Furthermore, after cell transplantation, HSPGs may be important for mediating the stress response in astrocytes via FGF2. Identification of factors secreted by Schwann cells that induce this negative response in astrocytes would further our ability to manipulate the inhibitory environment induced after injury to promote regeneration

Preparedness for use of the rapid result HIV self-test by gay men and other men who have sex with men (MSM): a mixed methods exploratory study among MSM and those involved in HIV prevention and care

Objectives: The aim of the study was to explore preparedness for the HIV self-test among men who have sex with men (MSM) and those involved in HIV prevention and care. Methods: A mixed methods exploratory research design was employed, detailing awareness and willingness to use the self-test and the perceived barriers and facilitators to implementation. Quantitative and qualitative data collection and analysis were completed in parallel. Descriptive and inferential analysis of cross-sectional bar-based survey data collected from MSM through a self-completed questionnaire and oral fluid specimen collection (n = 999) was combined with qualitative, thematic, analysis of data collected through 12 expert focus groups (n = 55) consisting of gay men, National Health Service (NHS) staff, community organizations, entrepreneurs and activists. Findings were subsequently combined and assessed for synergies. Results: Among MSM, self-test awareness was moderate (55%). Greater awareness was associated with increased educational attainment [adjusted odds ratio 1.51; 95% confidence interval (CI) 1.00–2.30; P = 0.05] and previous history of sexually transmitted infection (STI) testing (adjusted odds ratio 1.63; 95% CI 1.11–2.39; P = 0.01). Willingness to use the test was high (89%) and associated with meeting sexual partners online (unadjusted odds ratio 1.96; 95% CI 1.31–2.94; P &lt; 0.001). Experts highlighted the overall acceptability of self-testing; it was understood as convenient, discreet, accessible, and with a low burden to services. However, some ambivalence towards self-testing was reported; it could reduce opportunities to engage with wider services, wider health issues and the determinants of risk. Conclusions: Self-testing represents an opportunity to reduce barriers to HIV testing and enhance prevention and access to care. Levels of awareness are moderate but willingness to use is high. Self-testing may amplify health inequalities

Classification strategies for unbalanced binary maps : finding Ponderosa pine in the Willamette Valley

Forest species classifications are becoming increasingly automated as advances are made in machine learning. The algorithms used to identify tree species range from simple decision trees to intricate neural networks, and often excel in accurately delineating tree species. However, complex algorithms can have high input costs, including the cost of high resolution data and time required to train both the researcher and the algorithm. Furthermore, the proofs that support the performances of such algorithms frequently use small study areas while attempting to classify down to the individual tree level. Such precise techniques may be impractical for large-scale classifications, which instead may benefit from simpler, conventional methods of classification, such as maximum likelihood (ML). In this study, I compared the results of a human-guided maximum likelihood (HGML) classification with the results of an automated random forests (ARF) classification of ponderosa pine stands in the southern Willamette Valley, Oregon. The study area is approximately 816,600 ha, significantly larger than most study areas used for presenting techniques for tree species classification, which typically occur on a scale of a few thousand hectares. The goal of the classification was to identify contiguous stands of ponderosa pine against a mix of forest and non-forest background. The classifications were performed using 1m resolution RGBI aerial imagery from the USDA’s National Agriculture Imagery Program. Following classification, I applied a height mask from a 3m resolution lidar-derived canopy height model (CHM). The lidar data was acquired from the Oregon Lidar Consortium. The masks reduced the pine class commission error for mature mixed-conifer forests and non-forest vegetation areas. The HGML classifications achieved an average accuracy of about 63% (kappa 0.48), with a pine class producer accuracy (non-omitted pixels) of 74%, and user accuracy (non-committed pixels) of 60%. With CHM masks, the HGML classifications increased to 92% overall accuracy (kappa 0.60) with a 61% producer accuracy and 97% user accuracy for the pine class. The ARF classification achieved an 86% overall accuracy (kappa 0.46), with a pine class producer accuracy of 82% and user accuracy of 85%. With the application of a CHM mask, the ARF accuracies increased slightly: it reached 90% overall accuracy with a kappa of 0.49, with a 65% producer accuracy and a 93% user accuracy. These results suggest that while multiple classification methods can reach high accuracies in tree species classifications, the HGML method, when enhanced with a CHM mask, is more suitable for large-scale classifications of RGBI imagery, as is evident by its high kappa coefficient

Plasticity reveals hidden resistance to extinction under climate change in the global hotspot of salamander diversity

Extinction rates are predicted to rise exponentially under climate warming, but many of these predictions ignore physiological and behavioral plasticity that might buffer species from extinction. We evaluated the potential for physiological acclimatization and behavioral avoidance of poor climatic conditions to lower extinction risk under climate change in the global hotspot of salamander diversity, a region currently predicted to lose most of the salamander habitat due to warming. Our approach integrated experimental physiology and behavior into a mechanistic species distribution model to predict extinction risk based on an individual’s capacity to maintain energy balance with and without plasticity. We assessed the sensitivity of extinction risk to body size, behavioral strategies, limitations on energy intake, and physiological acclimatization of water loss and metabolic rate. The field and laboratory experiments indicated that salamanders readily acclimatize water loss rates and metabolic rates in ways that could maintain positive energy balance. Projections with plasticity reduced extinction risk by 72% under climate warming, especially in the core of their range. Further analyses revealed that juveniles might experience the greatest physiological stress under climate warming, but we identified specific physiological adaptations or plastic responses that could minimize the lethal physiological stress imposed on juveniles. We conclude that incorporating plasticity fundamentally alters ecological predictions under climate change by reducing extinction risk in the hotspot of salamander diversity

Adult patients with respiratory syncytial virus infection: impact of solid organ and hematopoietic stem cell transplantation on outcomes

BackgroundRespiratory syncytial virus (RSV) is a common community‐acquired pathogen responsible for a substantial disease burden in adults. We investigated the outcomes after RSV infection in hospitalized adults over a 3‐year period.MethodsThis single‐center, retrospective study identified 174 patients hospitalized with RSV upper or lower respiratory tract infection (LRTI) between January 1, 2009 and June 30, 2012. Clinical data were extracted from medical records. The primary outcome analyzed was all‐cause mortality, defined as death during the index hospital admission. Subjects were divided into 3 groups for comparison: hematopoietic stem cell transplant (HSCT) patients, solid organ transplant (SOT) patients, and non‐transplant patients.ResultsIn our study, 41/174 (23.6%) were HSCT recipients and 28/174 (16.1%) were SOT recipients. Twelve of 174 (6.9%) died. Death occurred in 2/41 (4.9%) HSCT and 3/28 (10.7%) SOT recipients, compared to 7/106 (6.6%) non‐transplant patients. When compared to the non‐transplant cohort, HSCT and SOT were not found to be significant risk factors for mortality (P = 0.685 and 0.645, respectively). In multivariate logistic regression, age >60 was associated with mortality (P = 0.019), while lymphopenia on admission trended toward an association with death (P = 0.054). HSCT patients were less likely to be admitted to an intensive care unit (odds ratio [OR] 0.26, P = 0.04), but were significantly more likely to receive ribavirin therapy (OR 11.62, P 60 or with lymphopenia on admission. This study did not identify any significant increased mortality or morbidity associated with RSV infection in immune suppressed transplant recipients vs. patients who had not received a transplant.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113135/1/tid12409.pd

Billiard Systems in Three Dimensions: The Boundary Integral Equation and the Trace Formula

We derive semiclassical contributions of periodic orbits from a boundary integral equation for three-dimensional billiard systems. We use an iterative method that keeps track of the composition of the stability matrix and the Maslov index as an orbit is traversed. Results are given for isolated periodic orbits and rotationally invariant families of periodic orbits in axially symmetric billiard systems. A practical method for determining the stability matrix and the Maslov index is described.Comment: LaTeX, 19 page