Field Perimeter Research Articles

Comparison of Visual Functions and Ocular Health in Children with Autism Spectrum Disorder versus Typically Developing Peers

PURPOSE: To compare the visual functions and ocular health between children with Autism Spectrum Disorder and Typically Developing Peers. METHOD: A comparative cross-sectional study was conducted in different autistic centers to evaluate the visual functions and ocular health of 80 individuals in which 40 were diagnosed with ASD and 40 were typically developing. Different tests were carried out to assess visual functions in which visual acuity was tested by Snellen chart, contrast sensitivity on Pelli-Robson, color vision by primary colors detection and visual field by handheld peripheral field perimeter. Ocular health was checked by ocular examination of individuals. RESULTS: Out of 40 children with ASD, 15(37.5%) had VA≤ 0.5. 19(23.75%) had reduced contrast sensitivity. 3(3.75%) had some color vision defect. Out of 40 TD peers, 17(42.5%) had VA≤ 0.5. 17(21.25%) had reduced contrast sensitivity. All TD peers had normal color vision. Both groups had 2(2.50%) individuals with reduced field. While checking ocular health of ASD group, only 20 had some ocular health problems in which 7(8.75%) had strabismus, 3(3.75%) had eye movement disorders, 2(2.50%) had hypertelorism and ptosis respectively and 1(1.25%) had nystagmus. Similarly, in TD group, 16 had ocular problems in which 6(7.50%) had strabismus, 2(2.50%) had hypertelorism, 1(1.25%) had ptosis and eye movement disorders respectively. The statistical test was performed by using Mann Whitney test and Chi-square test (p value ≤ 0.05). CONCLUSION: There was no significant difference in visual functions and ocular health of children who had ASD and TD Peers.

Remote Perimetry in a Virtual Reality Metaverse Environment for Out-of-Hospital Functional Eye Screening Compared Against the Gold Standard Humphrey Visual Fields Perimeter: Proof-of-Concept Pilot Study.

The growing global burden of visual impairment necessitates better population eye screening for early detection of eye diseases. However, accessibility to testing is often limited and centralized at in-hospital settings. Furthermore, many eye screening programs were disrupted by the COVID-19 pandemic, presenting an urgent need for out-of-hospital solutions. This study investigates the performance of a novel remote perimetry application designed in a virtual reality metaverse environment to enable functional testing in community-based and primary care settings. This was a prospective observational study investigating the performance of a novel remote perimetry solution in comparison with the gold standard Humphrey visual field (HVF) perimeter. Subjects received a comprehensive ophthalmologic assessment, HVF perimetry, and remote perimetry testing. The primary outcome measure was the agreement in the classification of overall perimetry result normality by the HVF (Swedish interactive threshold algorithm-fast) and testing with the novel algorithm. Secondary outcome measures included concordance of individual testing points and perimetry topographic maps. We recruited 10 subjects with an average age of 59.6 (range 28-81) years. Of these, 7 (70%) were male and 3 (30%) were female. The agreement in the classification of overall perimetry results was high (9/10, 90%). The pointwise concordance in the automated classification of individual test points was 83.3% (8.2%; range 75%-100%). In addition, there was good perimetry topographic concordance with the HVF in all subjects. Remote perimetry in a metaverse environment had good concordance with gold standard perimetry using the HVF and could potentially avail functional eye screening in out-of-hospital settings.

Evaluation of the Level of Farmland Infrastructure Based on High-Resolution Images of UAV

The evaluation of the level of farmland infrastructure is a necessary objective condition for the use of arable land and agricultural development. In order to investigate the evaluation index system and method of farmland infrastructure level, this article uses the Kenli District of the Yellow River Delta as the research region. In the study region, six typical observation sample areas are chosen. Each area receives high-resolution UAV photos, which are then used to extract information about the farmland infrastructure of the field. A farming infrastructure evaluation index system was built, consisting of 10 indexes for four aspects, including farmland roads, field plots, ditches, and forest belts, using the 100 m by 100 m grid method to divide the evaluation units. The comprehensive index technique was used to calculate the farmland infrastructure score of each unit and identify the degree of excellent, good, and poor farmland infrastructure. The weight of each indication was decided by the hierarchical analysis method. There were 20 excellent grades, 77 good grades, and 29 poor grades among the 126 evaluation units in the study area, with excellent and good grades accounting for 79.13% and area proportions of 14.29%, 64.84%, and 20.87%, respectively. Among the six sample areas, sample areas E and F had the highest percentages of excellent grades, sample area A had 82.62% of the good grades, and all sample areas except A and C had a percentage of poor grades that was higher than 20%. Regularity of the fields, average size of the fields, and the agricultural plot’s slope are the dominant indexes of farmland infrastructure in each observation sample area, and the indexes of the ratio of the perimeter of roads to the perimeter of fields, density of ditches, and the ratio of area of agricultural forest networks to area of fields need to be optimized and improved. The spatial distribution of each grade differs significantly. The evaluation results are consistent with the real situation in the study region and have positive reference meaning for the development and management of farming infrastructure, according to the study’s proposed evaluation system and methodology.

Field Tests of Three Alternative Insecticides with Protein Bait for the Development of an Insecticide Rotation Program to Control Melon Flies, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae).

Simple SummaryMelon flies in Hawaii have developed high levels of resistance to a widely used insecticidal bait containing the active ingredient spinosad. Since farmers relied heavily on this product and have few alternatives, we tested three other insectides mixed with a bait spray called Nu-Lure. The three products (Agri-Mek SC, Mustang Maxx, and Malathion 5EC) were all found to be effective in either decreasing melon fly numbers or suppressing the growth of the population in the field. When used one-by-one in rotation for two weeks per product at one-week intervals on a commercial zucchini farm, melon fly populations were dramatically reduced and the yield of zucchinis harvested was substantially increased.High levels of resistance to the spinosad-based insecticidal protein bait GF-120 have been detected in some populations of melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), in Hawaii in 2017. To provide cucurbit farmers in Hawaii with alternative insecticides, we field-tested the effectiveness of Agri-Mek SC (a.i., abamectin), Mustang Maxx (a.i., zeta-cypermethrin), and Malathion 5EC (a.i., malathion), added to a protein bait spray (Nu-Lure Insect Bait). The insecticide and protein bait combinations were applied to the roosting plants of Z. cucurbitae around the perimeter of the cucurbit fields at one-week intervals. When individually tested, all three insecticides in combination with protein bait significantly reduced or suppressed the numbers of female flies caught in torula yeast traps. A two-week rotation of weekly applications of the three insecticides and GF-120 significantly reduced Z. cucurbitae numbers on a commercial zucchini farm on Maui. The percentage of marketable fruits harvested increased from 51% to 98% after implementing the insecticide rotation. Our findings will be used to provide cucurbit farmers with additional products to control Z. cucurbitae. The future focus will be on educating cucurbit farmers to use the insecticide rotation strategy to prevent or delay resistance development.

A feasibility study on the application of mesh grids for heliostat wind load reduction

This study examines the effectiveness of mesh grids in heliostat field perimeter fences and edge-mounted devices for heliostat wind load reduction. Two experimental studies were conducted: (1) the effect of mesh porosity and non-dimensional longitudinal distance of a perimeter fence upstream on the forces on a heliostat, and (2) the effect of mesh porosity and non-dimensional height-chord ratio of a heliostat edge-mounted mesh device on the heliostat loads. The experiments were conducted using an instrumented heliostat model positioned in the atmospheric test section of the Adelaide Wind Tunnel. It was found that perimeter mesh fences reduce peak loads by up to 50% and edge-mounted porous mesh devices reduce peak loads by up to 30% at the expense of increasing loads at different elevation angles. The porosity and height-chord ratio of an edge-mounted mesh were found to be important parameters influencing the maximum drag and lift reductions in operating and stow positions. The results of this work show the potential of mesh grids for reducing wind load on heliostats, and the importance of conducting a detailed techno-economic analysis on mesh grids throughout a heliostat field. The application of mesh grids on commercial-scale heliostats requires a further evaluation of the reduction of heliostat wind loads and thus cost of a field through mitigation of the incoming ABL turbulence and wake-induced turbulence from upstream heliostats.

HYDROGEOLOGICAL AND HYDROGEOCHEMICAL INVESTIGATION OF ILICA (BALIKESIR) GEOTHERMAL FIELD

This study includes the first conceptual modeling studies in Ilıca Geothermal Region of Balıkesir Province. The hydraulic behavior and groundwater properties of the geothermal field were analyzed by conceptual modeling. For this purpose, he used Visual Modflow Flex software used in 3D modeling studies. Physical-chemical parameters and flow velocity from geothermal sources Faults and geological units in the field were mapped to describe the geothermal system. All data were digitized on a scale of 1/25000. Also, geothermal conceptual flow modeling is conceptually defined. The field perimeter is divided into 400 cells by 20 x 20 units. The area of each cell is designed to be 67.85 m x 67.85 m. Approximately 4.6 km2 has been studied. According to the data obtained, the geothermal aquifer is fed from cracked and hollow sections of marble and schists. The geothermal heater body is thought to be the granite pluton found in the region. Cover rocks of the geothermal system are young sedimentary units. Existing meteoric waters enter the underground through the cracks of the rocks in the region, warm up with a short flow path and are carried to the surface by faults.

Effects of agricultural landscape structure, insecticide residues, and pollen diversity on the life-history traits of the red mason bee Osmia bicornis

Agricultural landscapes have changed substantially in recent decades, shifting from the dominance of small fields (S) with diverse cropping systems toward large-scale monoculture (L), where landscape heterogeneity disappears. In this study, artificial nests of the red mason bee, Osmia bicornis, were placed in S and L landscape types on the perimeter of oilseed rape fields representing different oilseed rape coverages (ORC, % land cover). The local landscape structure around each nest was characterised within a 100, 200, 500, and 1000 m radius using ORC and 14 landscape characteristics, which were then reduced by non-metric multidimensional scaling (nMDS) to two axes: nMDS1 characterised the dataset primarily according to land fragmentation and the main crop, whereas nMDS2 captured the prevalence of more natural areas in the landscape. Pollen diversity and insecticide risk levels in the pollen provisions collected by the bees were analysed, and their dependence on the landscape structure was tested. Thereafter, the effects of pollen diversity, insecticide risk, and landscape structure on the life-history traits of bees and their sensitivity to topically applied Dursban 480 EC were determined. Pollen taxa richness in a single nest ranged from 3 to 12, and 34 pesticides were detected in the pollen at concentrations of up to 320 ng/g for desmedipham. The O. bicornis foraging range was relatively large, indicating that the landscape structure within a radius of ~1000 m around the nest is important for this species. Pollen diversity in the studied areas was of minor importance for bee performance, but the ORC or landscape structure significantly affected the life-history traits of the bees. Contamination of pollen with insecticides affected the bees by decreasing the mass of newly emerged adults but their sensitivity to Dursban 480 EC was not related to environmental variables.

Host plants as reservoirs of the main oil-producing cabbage crops pests in the eastern forest-steppe of Ukraine

Considering the geographical position of Ukraine, which is Such biotic factor as the vegetation distribution, which is the forage base for most insects, influences their spreading greatly. This connection is strongly expressed among the harmful herbivorous insects. The presence and distribution of the plants which are cultivated or used by humans and on which the insects are fed is certainly the first and basic condition for the emergence of a zone or a breeding ground of harmfulness. The presence of the most preferred by the insects fodder plants often leads to the formation of a zone or a center of the greatest damage (in the presence of other favorable conditions for the existence and reproduction of the pest). In the course of the researches concerning the identification of the host plants as reservoirs of the main oil producing cabbage crops pests which have been conducted in 2011–2014 in the communities (meadows, roadsides of highways and field perimeters) of the Kharkiv district of the Kharkiv region it has been found out the host plants as reservoirs for the dominant pests of the oil producing cabbage crops were dandelion, caustic buttercup, field mustard, hedge mustard, tansy mustard, yellow rocket and field shepherd’s purse. The largest number of species of the host plants as reservoirs was found on the roadsides of highways and along the field perimeters (6 species) and on the meadows (2 species).The cruciferous fleas, rape blossom beetles and cruciferous bugs visited such crops as field mustard, hedge mustard and yellow rocket most often. Field shepherd’s purse was the least significant among the identified host plants as reservoirs. Only a small amount of the cabbage fleas fed on this crop. This fact can be explained by the small white flowers that do not attract the rape blossom beetles and rose chafers as well as by a ground flat leaf rosette, which is always covered with dust and prevents the fleas and bugs from feeding.

Use of forested field edges by a blueberry insect pest, Rhagoletis mendax (Diptera: Tephritidae)

AbstractThe blueberry maggot fly, Rhagoletis mendax Curran, is a pest of wild and highbush blueberries. In wild blueberries, most flies colonize fields from forest edges annually. Flies were associated with forest canopies adjacent to colonized fields. Flies were captured up to 6 m high (limited by trap placement height) and may occur at greater tree heights. Fly abundance relative to tree species was highest in red oak. Releases of marked flies from tree canopies showed that release height had no effect on distance into the field that flies dispersed. This is important because the main fly control tactic is the application of a 25‐ to 30‐m‐wide swath of insecticide along field perimeters. In the laboratory, flies preferred leaves and leaf extracts of red oak compared to other leaf tree and shrub species, including blueberry. Electroantennographs demonstrated that the female antennae consistently responded to compounds extracted from red oak leaves. Mass spectra and gas chromatograph retention times of five antenna‐active compounds matched those of (i) trans‐β‐ocimene, (ii) linalool, (iii) 4,8‐dimethyl‐1,3,7‐nonatriene, (iv) indole, and (v) trans‐nerolidol. We speculate flies recruit to trees before movement into blueberry fields primarily for food, as supported by their arrestment response to leaf extracts.

The assessment of winter wheat agrocenoses adaptivity in the conditions of the submontane zone of the Central Caucasus

The article presents the results of 3 years study on the adaptation of the properties of various winter wheat varieties to the conditions of the submontane zone of the Central Caucasus. The indicator of the ontogenetic adaptability was the homeostaticity of the plants. We have studied thirty winter wheat varieties according to the parameters of ecological plasticity, productivity and resistance to the destructive complex of diseases and pests like Fusarium head blight, brown and yellow rust, Septoria blight, tan spot etc. The yield of the mixed variety crops was 4.5 t/ha; the increase was 9%. In the crops of the triple mixture of the strong Veda and Delta varieties (25%) with the valuable Batko variety (50%), which differed in resistance to various diseases, the average yield of 52 cwt/ha was obtained with the protein content of 12%, the gluten content of 28% and the flour strength of 320 a.u. The authors used the resistance of the precocious Kuma variety to the damage by the cereal leaf beetle as a protective screening crop along with the field perimeter. Such a screening crop of the stable variety prevents the colonization of the crops of the other less resistant varieties with pests. The genetic diversity of the variety creates the conditions for regulating and stabilizing the phytosanitary state of the crops and increasing their productivity. With this agrotechnical method, it becomes possible to regulate and stabilize the phytosanitary situation in the fields and to increase grain productivity and quality.

Field Perimeter Trapping to Manage Rhagoletis mendax (Diptera: Tephritidae) in Wild Blueberry.

Rhagoletis mendax Curran (the blueberry maggot fly) is a major pest of wild blueberry. It is a direct pest of the fruit. Females lay eggs in fruit resulting in infestations of larvae unacceptable to most consumers. Three field perimeter interception tactics were tested for control of R. mendax in wild blueberry, Vaccinium angustifolium Aiton (Ericales: Ericaceae), between 2000 and 2010. We investigated field perimeter deployment of baited, insecticide-treated, green spheres (2000-2005), baited, yellow Trécé PHEROCON AM traps (2005 and 2006), and baited, Hopper Finder, sticky barrier tape (2008-2010). Only the Hopper Finder tape provided significant reduction in R. mendax adults and fruit infestation over the 3-yr field study. However, the reduction in fruit infestation compared with control plots was only 48.2 ± 7.3%, a level of reduction in damage that would be unsuitable for many commercial wild blueberry growers as a stand-alone tactic, but could be an important reduction as part of a multiple tactic IPM strategy. In addition, we constructed an agent-based computer simulation model to assess optimal trap placement between three patterns: 1) a single row of traps along field perimeter; 2) a double row of traps along the field perimeter at half the density of the single row; and 3) a grid of traps spread throughout the field but with the largest distance between traps. We found that the single row deployment pattern of traps was the best for reducing immigration of R. mendax adults into simulated fields.

Comparing accuracy between global positioning systems and ultra-wideband-based position tracking systems used for tactical analyses in soccer

Current studies have reported high accuracy in global positioning system (GPS) and recently developed ultra-wideband (UWB)-based tracking systems for monitoring time – motion patterns. The accuracy and reliability of both systems may be different in tactical analysis application, an aspect that has never been studied previously. The aims of the present study were: (i) to determine and compare the accuracy of GPS and UWB technologies in soccer players’ positions (ii) to compare the tactical application of both systems. Following institutional ethical approval and familiarisation, 14 well-trained soccer players performed tests around five courses: (a) field perimeter, (b) halfway line, (c) centre circle, (d) perimeter of the penalty area, and (e) semicircle penalty area. Also, a small-sided game was played monitored with WIMUPRO™ to determine real and practical differences in accuracy of both systems in tactical analysis. For the GPS, the mean absolute error (N = 9445) of “x” and “y” coordinates was 41.23 ± 17.31 cm and 47.6 ± 8.97 cm, respectively. For UWB, it was 9.57 ± 2.66 cm and 7.15 ± 2.62 cm. The results of the “x” and “y” accuracy comparison were significantly lower in all cases (p < 0.05) with an ES of 0.78 and 0.95, respectively. In a real practical application, the differences of both systems reached 8.31% in typical tactical variables (ES = 0.11). In contrast to GPS-10Hz, UWB WIMUPRO™-20 Hz has been demonstrated to be an acceptable technology to estimate the position of players on the pitch with high accuracy and be a useful, automatic, and portable instrument for tactical analysis measurement.

GearVision: Smartphone Based Head Mounted Perimeter For Detection Of Visual Field Defects.

Automated visual field perimetry is widely used for the evaluation of visual field defects caused by ophthalmological and neurodegenerative diseases. This test is typically performed using the Humphrey Perimeter or Octopus Perimeter. However, their high cost and large footprint limit their use to the clinical setting. This in turn limits their reach especially in the context of screening in remote environments and personal setting. In this paper, we report the development and testing of GearVision, a portable, accessible and compact virtual reality based visual field perimeter. It enables regular visual field testing in a cost-effective and convenient manner. Currently, GearVision is meant to augment the existing perimetry system and hence facilitate the detection of visual field defects early and without expert supervision or the need for hospital visits. In addition to the development of standard 30-2 suprathreshold and full threshold perimetry tests, we have proposed methods to improve test reliability and compliance. These include optional rest intervals during the test to reduce errors caused by strain or fatigue and improved false positive estimation based on statistical analysis of a patient's response times. We have tested the proposed system on 21 subjects and validated its capability to detect visual field defects.

Trapping system comparisons for and factors affecting populations of Drosophila suzukii and Zaprionus indianus in winter-grown strawberry.

Drosophila suzukii (Matsumura) is a major fruit pest in temperate regions worldwide, but in subtropical Florida, winter-grown strawberries have not been severely affected. Zaprionus indianus Gupta is another invasive drosophilid species and a pest of some tropical fruits. To improve monitoring, trapping systems for D. suzukii and Z. indianus were tested. Morphology, ovarian status and the suitability and availability of non-crop hosts as possible D. suzukii population-limiting factors were assessed. Traps with commercial attractants captured more D. suzukii but fewer Z. indianus than those with a homemade mixture. In central and northern Florida, < 10% and 30-80% of D. suzukii, respectively, exhibited darker, winter morph coloration, and 55-75% of females from central Florida were carrying mature and/or immature eggs. Adult D. suzukii were reared from fruits of two of 28 potential hosts: elderberry (Sambucus nigra) and nightshade (Solanum americanum). Nightshade, but not elderberry, was common on field perimeters (21 and six of 36 fields, respectively). Traps placed in wooded or partially wooded field edges yielded the most D. suzukii. Florida strawberry is at risk of D. suzukii infestation, as flies were captured throughout the growing season. However, fly captures remained relatively low, peaking at 1.5 flies per trap per day. In central Florida, the low availability and suitability of non-crop hosts likely limit population growth. The finding of few flies in northern Florida may additionally be attributable to a greater proportion of flies displaying winter morph coloration than in central Florida. © 2018 Society of Chemical Industry.

System Control Applications of Low-Power Radio Frequency Devices

This paper conceptualizes a low-power wireless sensor network design for application employment to reduce theft of portable computer devices used in educational institutions today. The aim of this study is to design and develop a reliable and robust wireless network that can eradicate accessibility of a device’s human interface. An embedded system supplied by an energy harvesting source, installed on the portable computer device, may represent one of multiple slave nodes which request regular updates from a standalone master station. A portable computer device which is operated in an undesignated area or in a field perimeter where master to slave communication is restricted, indicating a possible theft scenario, will initiate a shutdown of its operating system and render the device unusable. Consequently, an algorithm in the device firmware may ensure the necessary steps are executed to track the device, irrespective whether the device is enabled. Design outcomes thus far indicate that a wireless network using low-power embedded hardware, is feasible for anti-theft applications. By incorporating one of the latest Bluetooth low-energy, ANT+, ZigBee or Thread wireless technologies, an anti-theft system may be implemented that has the potential to reduce major portable computer device theft in institutions of digitized learning.

Clinical applications of a visual field perimeter with binocular video imaging

PurposeThe majority of visual field testing equipment is designed for monocular tests only: most instruments do not have the capability to visualize both eyes simultaneously and many do not have a head rest position suitable for binocular testing. This presentation will focus on the clinical applications of the binocular visual field tests available on the MonCvONE perimeter.MethodsBinocular testing is very important for functional evaluations. Extrapolation from monocular tests is inaccurate as phenomenons such as integration, suppression, ocular deviation, cyclotorsion, … affect differently monocular and binocular vision. The MonCvONE perimeter combines a binocular video sensor with the possibility of video recording to the possibility of controlling the exam with an interactive mode similar to the Goldmann perimeter.ResultsClinical examples of binocular perimetry will be presented including ‐ the evaluation of ptosis with a documentation of the gain in visual field area in relationship with the opening of the eye lids. ‐ the assessment of low vision with the Esterman technique ‐ the evaluation of drivers’ visual field in agreement with the European Community directive ‐ the evaluation of the field of single vision with the determination of a diplopia score‐ the test of the visual field in young infants when eye occlusion and head immobility are not easily obtainedConclusionsThese examples demonstrate the clinical usefulness of binocular visual field testing with video recording

Assessment of groundwater vulnerability in the Daule aquifer, Ecuador, using the susceptibility index method

The Guayas region in Ecuador is economically very important, producing 68% of the national crops. The main agricultural activities threaten the groundwater therein with nitrate contamination given the large fertiliser and water needs. The present work tests the applicability of the susceptibility index assessment method in evaluating the impact of agricultural activities on groundwater quality, using as a case study an aquifer of the Guayas river basin in Ecuador. The index adapts four parameters of the DRASTIC method and incorporated a new land use parameter. Results show that the areas highly vulnerable to contamination are located in irrigation perimeters of dominant paddy fields associated with the high recharge rates in the alluvial deposits. Respectively, moderately vulnerable and low-vulnerability areas correspond to aquatic environments and forests, semi-natural zones and water bodies. One of the main contributions of the Daule aquifer vulnerability is likely its wide, flat topography. A great part of the aquifer is at high risk of contamination by nitrates if a code of good agricultural practices is not applied. Therefore the implementation of a monitoring network to control the nitrates concentrations is the first step to assure groundwater quality for drinking purposes.

An isogeometric approach to topology optimization of multi-material and functionally graded structures

A new isogeometric density-based approach for the topology optimization of multi-material structures is presented. In this method, the density fields of multiple material phases are represented using the isogeometric non-uniform rational B-spline-based parameterization leading to exact modeling of the geometry, removing numerical artifacts and full analytical computation of sensitivities in a cost-effective manner. An extension of the perimeter control technique is introduced where restrictions are imposed on the perimeters of density fields of all phases. Consequently, not only can one control the complexity of the optimal design but also the minimal lengths scales of all material phases. This leads to optimal designs with significantly enhanced manufacturability and comparable performance. Unlike the common element-wise or nodal-based density representations, owing to higher order continuity of density fields in this method, their gradients required for perimeter control restrictions are calculated exactly without additional computational cost. The problem is formulated with constraints on either (1) volume fractions of different material phases or (2) the total mass of the structure. The proposed method is applied for the minimal compliance design of two-dimensional structures consisting of multiple distinct materials as well as functionally graded ones. Copyright © 2016 John Wiley & Sons, Ltd.

Are simple IMRT beams more robust against MLC error? Exploring the impact of MLC errors on planar quality assurance and plan quality for different complexity beams.

This study investigated the impact of beam complexities on planar quality assurance and plan quality robustness by introducing MLC errors in intensity‐modulate radiation therapy. Forty patients' planar quality assurance (QA) plans were enrolled in this study, including 20 dynamic MLC (DMLC) IMRT plans and 20 static MLC (SMLC) IMRT plans. The total beam numbers were 150 and 160 for DMLC and SMLC, respectively. Six different magnitudes of MLC errors were introduced to these beams. Gamma pass rates were calculated by comparing error‐free fluence and error‐induced fluence. The plan quality variation was acquired by comparing PTV coverage. Eight complexity scores were calculated based on the beam fluence and the MLC sequence. The complexity scores include fractal dimension, monitor unit, modulation index, fluence map complexity, weighted average of field area, weighted average of field perimeter, and small aperture ratio (<5cm2 and<50 cm2). The Spearman's rank correlation coefficient was calculated to analyze the correlation between these scores and gamma pass rate and plan quality variation. For planar QA, the most significant complexity index was fractal dimension for DMLC (p=−0.40) and weighted segment area for SMLC (p=0.27) at low magnitude MLC error. For plan quality, the most significant complexity index was weighted segment perimeter for DMLC (p=0.56) and weighted segment area for SMLC (p=0.497) at low magnitude MLC error. The sensitivity of planar QA was weakly associated with the field complexity with low magnitude MLC error, but the plan quality robustness was associated with beam complexity. Plans with simple beams were more robust to MLC error.PACS number(s): 87.55

Elk resource selection patterns in a semiarid riparian corridor

Elk (Cervus elaphus) have depredated corn at Bosque del Apache National Wildlife Refuge (BDANWR), New Mexico, USA, which has interfered with the refuge's ability to provide supplemental nutrition to overwintering sandhill cranes (Grus canadensis) and other waterbirds. To identify management options for minimizing cropland depredation, we examined elk resource selection patterns using negative binomial generalized linear mixed models. We used 8,244 global positioning system (GPS) locations collected from 9 adult female elk to model fine-scale resource use (sampling units were 100 × 100-m cells; n = 3,646) and corn field use (sampling units were corn fields; n = 18) by a resident herd along the Rio Grande River in central New Mexico, USA. The fine-scale model suggested that elk use in cropland areas increased when alfalfa and corn were present and elk use was greatest 0.14 km from uncultivated areas. Elk use in uncultivated areas increased as canopy cover increased. Elk use exhibited a quadratic relationship with hiding cover, which varied with distance to cropland. We validated the fine-scale model with an independent sample of radio-marked adult female elk (n = 12; 1,106 locations). The fine-scale model was successful in predicting elk use; 84.1% (SE = 1.1) of radio-marked elk locations fell within high or medium-high use cells. Corn field use models indicated that elk use increased as the proportion of the corn field perimeter adjacent to alfalfa increased. Elk use of corn fields declined as distance to uncultivated areas and the proportion of other corn fields at the same growth stage increased. Probability of elk use peaked when corn reached heights of 1.4 m to 1.7 m and use varied with distance to uncultivated areas. Corn fields at these heights were in the late vegetative or tassel-milk growth stage, which are the stages at which damage to corn plants is most detrimental to yield. The average distance each elk moved per day during the corn growing season was 5,013 m (SD = 957) and varied among individuals (3,251–6,317 m). This is relatively large in relation to the size of the managed floodplain at BDANWR. Our results, couched in elk daily movements, can help direct crop management, vegetation manipulation, and timing of hazing efforts aimed at reducing elk use of crops. © 2016 The Authors. Journal of Wildlife Management Published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.