Clinical Characteristics and Burden of Illness in Pediatric Patients with Narcolepsy

Abstract Background: Narcolepsy is a chronic and lifelong neurologic disorder with onset commonly occurring in childhood or adolescence, and affecting approximately 0.025% to 0.05% of the general population. The primary symptom is excessive daytime sleepiness, which is accompanied by cataplexy in 70% of patients. Other common symptoms include sleep paralysis, hallucinations upon falling asleep or waking, and disrupted nocturnal sleep. Narcolepsy is associated with a considerable burden of illness (BOI), which has been well characterized in adults, and is exacerbated by delays in symptom recognition, diagnosis, and intervention. METHODS: This review describes the specific characteristics and BOI of pediatric narcolepsy, using a wide range of published research data. RESULTS: Pediatric narcolepsy presents distinct challenges in diagnosis and management. Narcolepsy symptoms often initially manifest differently in children and adolescents versus adults, which may pose diagnostic dilemmas. Children often respond to sleepiness with irritability, hyperactivity, and poor attention, which may be misinterpreted as misbehavior or neurocognitive sequelae of other conditions. Pediatric cataplexy symptoms may include subtle and unusual facial expressions or choreic-like movements, which are not observed in adults. Insufficient sleep and circadian rhythm disorders presenting with excessive daytime sleepiness are common in adolescents, potentially confounding narcolepsy diagnosis. Pediatric narcolepsy is also associated with comorbidities including rapid weight gain, precocious puberty, and attention deficit hyperactivity disorder, and increased risk for deficits in social functioning, depression, and anxiety. School performance is also typically impaired, requiring special education services. CONCLUSIONS: Thus, the discrete BOI of pediatric narcolepsy underscores the need for prompt and accurate diagnosis, and appropriate treatment of this disorder

Effects of grassland alteration from mowing and fire on bird activity at a Colorado airfield

Grass management has been used for many years at airports in an attempt to reduce numbers of birds and other wildlife and the collisions with aircraft associated with them. We evaluated the impacts of grassland alteration by mowing and fi re on the abundance, diversity, and frequency of birds using 1 control and 2 experimental grass plots from 2009 to 2010 on a U.S. Army airfield in Colorado located in short-grass prairie. Density of breeding birds was highest in the mowed plot. Numbers of birds observed in 34 surveys conducted during the non-breeding season in the burned (x = 41) and mowed (x = 24) plots were greater than in an unmanaged control (x = 7) plot. Bird species diversity in the nonbreeding season was greatest in the control plot. Horned larks (Eremophila alpestris) was the most frequently observed bird species and occurred in high numbers on the burned and mowed plots, possibly because of its preference for short vegetation and bare ground. This species is recognized as hazardous to aircraft in part because of its habit of forming large flocks in the nonbreeding season. All 3 study plots were dominated by grasses and forbs, with minimal shrub and cactus cover. Litter cover was greatest on the control plot, while the burned plot had the greatest coverage of bare ground. Results from this study are limited because the small size of the airfield precluded placement of multiple treatment plots. Additional study in larger airfields with multiple treatment plots would be required before management recommendations regarding the use of fi re and mowing can be made for airfields in areas with short-grass prairie

What does airborne LiDAR really measure in upland ecosystems?

Copyright © 2014 John Wiley & Sons, Ltd.Airborne laser scanning systems (Light Detection And Ranging, LiDAR) are very well suited to the study of landscape and vegetation structure over large extents. Spatially distributed measurements describing the three-dimensional character of landscape surfaces and vegetation architecture can be used to understand eco-geomorphic and ecohydrological processes, and this is particularly pertinent in peatlands given the increasing recognition that these landscapes provide a variety of ecosystem services (water provision, flood mitigation and carbon sequestration). In using LiDAR data for monitoring peatlands, it is important to understand how well peatland surface structures (with fine length scales) can be described. Our approach integrates two laser scanning technologies, namely terrestrial laser scanning (TLS) and airborne LiDAR surveys, to assess how effective airborne LiDAR is at measuring these fine-scale microtopographic ecohydrological structures. By combining airborne and TLS, we demonstrate an improved spatial understanding of the signal measured by the airborne LiDAR. Critically, results demonstrate that LiDAR digital surface models are subject to specific errors related to short-sward ecosystem structure, causing the vegetation canopy height and surface-drainage network depth to be underestimated. TLS is shown to be effective at describing these structures over small extents, allowing the information content and accuracy of airborne LiDAR to be understood and quantified more appropriately. These findings have important implications for the appropriate degree of confidence ecohydrologists can apply to such data when using them as a surrogate for field measurements. They also illustrate the need to couple LiDAR data with ground validation data in order to improve assessment of ecohydrological function in such landscapes. © 2014 John Wiley & Sons, Ltd.South West Water LtdUniversity of Exete

Residual biomass calculation from individual tree architecture using terrestrial laser scanner and ground-level measurements

Large quantity of residual biomass with possible energy and industrial end can be obtained from management operations of urban forests. The profitability of exploiting this resource is conditioned by the amount of existing biomass within urban community ecosystems. Prior research pointed out that residual biomass from Platanus hispanica and other tree species can be calculated from dendrometric parameters. In this study, two approaches have been analyzed: First, applicability of TLS was tested for residual biomass calculation from crown volume. In addition, traditional models for residual biomass prediction were developed from dendrometric parameters (tree height, crown diameter, and diameter at breast height). Next, a comparison between parameters obtained with both methodologies (standard methodologies vs TLS) was carried out. The results indicate a strong relationship (R2 = 0.906) between crown diameters and between total tree heights (R2 = 0.868). The crown volumes extracted from the TLS point cloud were calculated by 4 different methods: convex hull; convex hull by slices of 5 cm height in the XY plane; triangulation by XY flat sections, and voxel modeling. The highest accuracy was found when the voxel method was used for pruned biomass prediction (R2 = 0.731). The results revealed the potential of TLS data to determine dendrometric parameters and biomass yielded from pruning quitar of urban forestsFernández-Sarría, A.; Velázquez Martí, B.; Sajdak, M.; Martinez, L.; Estornell Cremades, J. (2013). Residual biomass calculation from individual tree architecture using terrestrial laser scanner and ground-level measurements. Computers and Electronics in Agriculture. 93:90-97. doi:10.1016/j.compag.2013.01.012S90979

Determining leaf area index and leafy tree roughness using terrestrial laser scanning

Vegetation roughness, and more specifically forest roughness, is a necessary component in better defining flood dynamics both in the sense of changes in river catchment characteristics and the dynamics of forest changes and management. Extracting roughness parameters from riparian forests can be a complicated process involving different components for different required scales and flow depths. For flow depths that enter a forest canopy, roughness at both the woody branch and foliage level is necessary. This study attempts to extract roughness for this leafy component using a relatively new remote sensing technique in the form of terrestrial laser scanning. Terrestrial laser scanning is used in this study due to its ability to obtain millions of points within relatively small forest stands. This form of lidar can be used to determine the gaps present in foliaged canopies in order to determine the leaf area index. The leaf area index can then be directly input into resistance equations to determine the flow resistance at different flow depths. Leaf area indices created using ground scanning are compared in this study to indices calculated using simple regression equations. The dominant riparian forests investigated in this study are planted and natural poplar forests over a lowland section of the Garonne River in Southern France. Final foliage roughness values were added to woody branch roughness from a previous study, resulting in total planted riparian forest roughness values of around Manning's n = 0.170–0.195 and around n = 0.245–330 for in-canopy flow of 6 and 8 m, respectively, and around n = 0.590 and around n = 0.750 for a natural forest stand at the same flow depths

Innovative LIDAR 3D Dynamic Measurement System to Estimate Fruit-Tree Leaf Area

In this work, a LIDAR-based 3D Dynamic Measurement System is presented and evaluated for the geometric characterization of tree crops. Using this measurement system, trees were scanned from two opposing sides to obtain two three-dimensional point clouds. After registration of the point clouds, a simple and easily obtainable parameter is the number of impacts received by the scanned vegetation. The work in this study is based on the hypothesis of the existence of a linear relationship between the number of impacts of the LIDAR sensor laser beam on the vegetation and the tree leaf area. Tests performed under laboratory conditions using an ornamental tree and, subsequently, in a pear tree orchard demonstrate the correct operation of the measurement system presented in this paper. The results from both the laboratory and field tests confirm the initial hypothesis and the 3D Dynamic Measurement System is validated in field operation. This opens the door to new lines of research centred on the geometric characterization of tree crops in the field of agriculture and, more specifically, in precision fruit growing

Testing the application of terrestrial laser scanning to measure forest canopy gap fraction

Terrestrial laser scanners (TLS) have the potential to revolutionise measurement of the three-dimensional structure of vegetation canopies for applications in ecology, hydrology and climate change. This potential has been the subject of recent research that has attempted to measure forest biophysical variables from TLS data, and make comparisons with two-dimensional data from hemispherical photography. This research presents a systematic comparison between forest canopy gap fraction estimates derived from TLS measurements and hemispherical photography. The TLS datasets used in the research were obtained between April 2008 and March 2009 at Delamere Forest, Cheshire, UK. The analysis of canopy gap fraction estimates derived from TLS data highlighted the repeatability and consistency of the measurements in comparison with those from coincident hemispherical photographs. The comparison also showed that estimates computed considering only the number of hits and misses registered in the TLS datasets were consistently lower than those estimated from hemispherical photographs. To examine this difference, the potential information available in the intensity values recorded by TLS was investigated and a new method developed to estimate canopy gap fraction proposed. The new approach produced gap fractions closer to those estimated from hemispherical photography, but the research also highlighted the limitations of single return TLS data for this application

Living on the edge: utilising lidar data to assess the importance of vegetation structure for avian diversity in fragmented woodlands and their edges

Context: In agricultural landscapes, small woodland patches can be important wildlife refuges. Their value in maintaining biodiversity may, however, be compromised by isolation, and so knowledge about the role of habitat structure is vital to understand the drivers of diversity. This study examined how avian diversity and abundance were related to habitat structure in four small woods in an agricultural landscape in eastern England. Objectives: The aims were to examine the edge effect on bird diversity and abundance, and the contributory role of vegetation structure. Specifically: what is the role of vegetation structure on edge effects, and which edge structures support the greatest bird diversity? Methods: Annual breeding bird census data for 28 species were combined with airborne lidar data in linear mixed models fitted separately at (i) the whole wood level, and (ii) for the woodland edges only. Results: Despite relatively small woodland areas (4.9–9.4 ha), bird diversity increased significantly towards the edges, being driven in part by vegetation structure. At the whole woods level, diversity was positively associated with increased vegetation above 0.5 m and especially with increasing vegetation density in the understorey layer, which was more abundant at the woodland edges. Diversity along the edges was largely driven by the density of vegetation below 4 m. Conclusions: The results demonstrate that bird diversity was maximised by a diverse vegetation structure across the wood and especially a dense understorey along the edge. These findings can assist bird conservation by guiding habitat management of remaining woodland patches

Retrieving Leaf Area Index (LAI) Using Remote Sensing: Theories, Methods and Sensors

The ability to accurately and rapidly acquire leaf area index (LAI) is an indispensable component of process-based ecological research facilitating the understanding of gas-vegetation exchange phenomenon at an array of spatial scales from the leaf to the landscape. However, LAI is difficult to directly acquire for large spatial extents due to its time consuming and work intensive nature. Such efforts have been significantly improved by the emergence of optical and active remote sensing techniques. This paper reviews the definitions and theories of LAI measurement with respect to direct and indirect methods. Then, the methodologies for LAI retrieval with regard to the characteristics of a range of remotely sensed datasets are discussed. Remote sensing indirect methods are subdivided into two categories of passive and active remote sensing, which are further categorized as terrestrial, aerial and satellite-born platforms. Due to a wide variety in spatial resolution of remotely sensed data and the requirements of ecological modeling, the scaling issue of LAI is discussed and special consideration is given to extrapolation of measurement to landscape and regional levels