The lumbar spine has an intrinsic shape specific to each individual that remains a characteristic throughout flexion and extension

Peer reviewedPostprin

Performance of Multi-Beacon DGPS

Historically, maritime organizations seeking accurate shipboard positioning have relied upon some form of differential GNSS, such as DGPS, WAAS, or EGNOS, to improve the accuracy and integrity of the GPS. Groundbased augmentation systems, such as DGPS, broadcast corrections to the GPS signal from geographically distributed terrestrial stations, often called beacons. Specifically, pseudorange corrections for the GPS L1 C/A signal are computed at each reference site, then broadcast in the nearby geographic area using a medium frequency (approximately 300 kHz) communications link. The user then adds these corrections onto their measured pseudoranges before implementing a position solution algorithm. Within the United States, the U.S. Coast Guard operates 86 DGPS reference beacons. Similar DGPS systems are operated in Europe and elsewhere around the globe. While current DGPS receiver algorithms typically use one set of pseudorange corrections from one DGPS reference site (often the one with the “strongest” signal), many user locations can successfully receive two or more different DGPS broadcasts. This brings to mind obvious questions: “If available, how does one select the corrections to use from multiple sets of corrections?” and “Is it advantageous to combine corrections in some way?” We note that a number of factors might influence the effectiveness of any particular station’s corrections. Some of these refer to the effectiveness of the communications link itself, including concerns about interference from other beacons (skywave interference from far-away beacons on similar frequencies, a notable problem in Europe) and self-interference (skywave fading). Other factors refer to the accuracies of pseudorange corrections. For example, ionospheric storm-enhanced plasma density (SED) events can cause the corrections to have large spatial variation, making them poor choices even for users close to a beacon. Earlier work in the area of DGPS beacon selection has identified several options including choosing the beacon closest to the user or the beacon with the least skywave interference. There have also been suggestions on how to combine corrections when multiple beacons are available. The most common of these is a weighted sum of the corrections, where the weights are typically inversely proportional to the distance from the user to the individual beacon. This paper reexamines the concept of multi-beacon DGPS by evaluating methods of combining beacon corrections based on spatial relativity. Of relevance to this topic is our recent observation that DGPS accuracy performance is biased. The mean of the error scatter with DGPS corrections does not fall on the actual receiver position. We established this both by processing GPS L1 C/A observables from hundreds of CORS (Continuously Operating References Station) sites around the U.S.A. and via simulation using a Spirent GSS8000 GPS simulator. Specifically, we found that the position solution computed using DGPS beacon corrections is typically biased in a direction away from the beacon, and that the size of the bias depends upon the distance from the beacon. This bias grows with a slope of approximately one-third of a meter per 100 km of user-to-beacon distance. This paper compares the performance of several multibeacon algorithms assessed using GPS simulator data. These algorithms include the nearest beacon, a weighted sum based on distances, and a spatial linearly-interpolated correction using the actual locations of the transmitters (distance and angle). We note that as part of this research effort we developed a DGPS receiver using software-defined radio (USRP). A complete description of this system is included in the paper

Variation in lifting kinematics related to individual intrinsic lumbar curvature:An investigation in healthy adults

Objective Lifting postures are frequently implicated in back pain. We previously related responses to a static load with intrinsic spine shape, and here we investigate the role of lumbar spine shape in lifting kinematics. Methods Thirty healthy adults (18-65 years) performed freestyle, stoop and squat lifts with a weighted box (6-15 kg, self-selected) while being recorded by Vicon motion capture. Internal spine shape was characterised using statistical shape modelling (SSM) from standing mid-sagittal MRIs. Associations were investigated between spine shapes quantified by SSM and peak flexion angles. Results Two SSM modes described variations in overall lumbar curvature (mode 1 (M1), 55% variance) and the evenness of curvature distribution (mode 2 (M2), 12% variance). M1 was associated with greater peak pelvis (r=0.38, p=0.04) and smaller knee flexion (r=-0.40, p=0.03) angles; individuals with greater curviness preferred to lift with a stooped lifting posture. This was confirmed by analysis of those individuals with very curvy or very straight spines (|M1|&gt;1 SD). There were no associations between peak flexion angles and mode scores in stoop or squat trials (p&gt;0.05). Peak flexion angles were positively correlated between freestyle and squat trials but not between freestyle and stoop or squat and stoop, indicating that individuals adjusted knee flexion while maintaining their preferred range of lumbar flexion and that 'squatters' adapted better to different techniques than 'stoopers'. Conclusion Spinal curvature affects preferred lifting styles, and individuals with curvier spines adapt more easily to different lifting techniques. Lifting tasks may need to be tailored to an individual's lumbar spine shape.</p

Antenna Near-Field Probe Station Scanner

A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described

Significant morphological change in osteoarthritic hips identified over 6-12 months using Statistical Shape Modelling

Acknowledgements We are grateful to all the study participants. We thank Lana Gibson and Jennifer Scott for their expertise with the iDXA scanner as well as iDXA precision data. Funding source This study was supported by an award (Ref: WHMSB_AU068/071) from the Translational Medicine Research Collaboration – a consortium made up of the Universities of Aberdeen, Dundee, Edinburgh and Glasgow, the four associated NHS Health Boards (Grampian, Tayside, Lothian and Greater Glasgow & Clyde), Scottish Enterprise and initially Wyeth, now Pfizer. The funder had no involvement in the collection, analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. Dr J.S. Gregory was the holder of an MRC New Investigator award (Ref: G0901242).Peer reviewedPostprin

Genetics of Perceived Family Interaction From 12 to 17 Years of Age

Correction: Volume: 49 Issue: 5 Pages: 484-484 DOI: 10.1007/s10519-019-09963-w Published: SEP 2019We analyzed how the effects of genetic and environmental factors on the perceptions of family interaction change from early to late adolescence. The data were collected by postal surveys on Finnish twins (N=4808) at 12, 14 and 17years of age and analyzed using genetic twin modeling. Additive genetic factors explained a modest share of the variation in perceived relational support (a(2)=0.30 in boys and 0.18 in girls) and relational tensions (a(2)=0.13 and 0.14, respectively) at 12years of age, with the proportions becoming larger through 17years of age (a(2)=0.53 in boys and 0.49 in girls for relational support; a(2)=0.35 in boys and 0.33 in girls for relational tensions). Simultaneously, the role of environment shared by co-twins decreased. These findings suggest that the associations between perceived family interaction and other factors in adulthood should be interpreted with caution, because they partly reflect genetic background, whereas in childhood, they may provide more reliable information on parental characteristics.Peer reviewe

Reproducibility and Diagnostic Accuracy of Kellgren-Lawrence Grading for Osteoarthritis Using Radiographs and Dual-Energy X-ray Absorptiometry Images

Copyright © 2014 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved. The authors would like to thank all the study volunteers, radiographers Lana Gibson and Jennifer Scott as well as Carol McKerron for administrative support. The acquisition of scans was supported in part by an award (Ref: WHMSB_AU_068_071) from the Translational Medicine Research Initiative - a consortium made up of the Universities of Aberdeen, Dundee, Edinburgh and Glasgow, the four associated NHS Health Boards (Grampian, Tayside, Lothian and Greater Glasgow & Clyde), Scottish Enterprise and Pfizer. Kanako Yoshida is funded by the Grampian Osteoporosis Trust (GOT). Jennifer Gregory is supported by the Medical Research Council [G0901242].Peer reviewedPostprin

Prospectus, November 29, 1989

https://spark.parkland.edu/prospectus_1989/1030/thumbnail.jp

Air-Stimulated ATP Release from Keratinocytes Occurs through Connexin Hemichannels

Cutaneous ATP release plays an important role in both epidermal stratification and chronic pain, but little is known about ATP release mechanisms in keratinocytes that comprise the epidermis. In this study, we analyzed ATP release from cultured human neonatal keratinocytes briefly exposed to air, a process previously demonstrated to trigger ATP release from these cells. We show that exposing keratinocytes to air by removing media for 15 seconds causes a robust, long-lasting ATP release. This air-stimulated ATP release was increased in calcium differentiated cultures which showed a corresponding increase in connexin 43 mRNA, a major component of keratinocyte hemichannels. The known connexin hemichannel inhibitors 1-octanol and carbenoxolone both significantly reduced air-stimulated ATP release, as did two drugs traditionally used as ABC transporter inhibitors (glibenclamide and verapamil). These same 4 inhibitors also prevented an increase in the uptake of a connexin permeable dye induced by air exposure, confirming that connexin hemichannels are open during air-stimulated ATP release. In contrast, activity of the MDR1 ABC transporter was reduced by air exposure and the drugs that inhibited air-stimulated ATP release had differential effects on this transporter. These results indicate that air exposure elicits non-vesicular release of ATP from keratinocytes through connexin hemichannels and that drugs used to target connexin hemichannels and ABC transporters may cross-inhibit. Connexins represent a novel, peripheral target for the treatment of chronic pain and dermatological disease