3,314 research outputs found

    The effect of modular tapered fluted stems on proximal stress shielding in the human femur.

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    Modular hip implants are currently being used in total hip arthroplasty revision procedures because it is common to have little or no bone left in the proximal region of the femur and it is difficult to accurately size implants based off of radiographs or other medical imaging techniques. The effect of modular systems using tapered fluted stems on proximal stress shielding in the human femur is the focus of this study. Seven modular implants were press-fit into seven femurs, where there was little or no contact between the modular body and the test femur. Finally, hydroxyapatite bone cement was added to create an interface between the modular body and femur. Stress shielding is perhaps one of the most critical complications that occur after total hip arthroplasty (THA). Insertion of the prosthesis permanently alters the stress distribution in the human femur. Stress shielding occurs in those areas in which a bone experiences a reduction of stress. Essentially, the prosthesis shields the stress from the bone by transmitting the force through the implant rather than the bone, which can lead to a decrease in bone mineral density due to the reduction of stress or failure of the implant itself. Seven test femurs were instrumented with strain gages to measure the strain at three different levels. Two loading conditions were applied to represent the forces exerted on the femur when a human is in a natural standing position. The loading conditions were applied to the intact femur: when the prosthesis was inserted into the femur with a press-fit; and when hydroxyapatite bone cement was injected around the implant in the proximal region. All femurs exhibited stress shielding effects after surgically inserting the modular implants. The experimental data confirmed that the greatest amount of stress shielding occurred primarily in the proximal and mid-stem regions. The strains at the junction between the modular body and stem were relatively low. The experimental data also confirmed that with the addition of BoneSource® Hydroxyapatite cement the strain in the proximal and mid-stem regions significantly increased, but stress shielding still occurred. The strains at the junction between the body and stem also decreased

    Carbon Footprint: A New Farm Management Consideration in the Southern High Plains

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    As concerns continue to mount regarding man induced impacts to the global climate, the SHPT region could be faced with a unique scenario in which the net carbon balance should be considered in the producer’s enterprise selection and production systems. Currently, the SHPT produces nearly one third of the U.S. cotton crop. Under a potential cap and trade system the challenge for the agricultural industry in the SHPT may be how to sustain the region’s economic base and production capabilities. Thus, the objective of this study was to measure the net carbon relationships between irrigated cotton and irrigated corn production systems on the SHPT using data from the Texas Alliance for Water Conservation (TAWC, 2009). Due to the unique management and production challenges in the SHPT, additional comparisons were made regarding economic viability and irrigation efficiency. Within the parameters of this study, it is apparent that irrigated corn has an advantage over cotton in both its ability to return carbon to the soil, maintain profitability, and use water resources efficiently. If the agricultural industry is included in CO2 regulation, it would appear that irrigated agricultural producers in the SHPT who have the ability to move between irrigated cotton and corn should be aware of the advantages corn possesses. However, even under changing commodity prices and profitability scenarios, corn still presents a significant advantage over cotton in its ability to reduce atmospheric CO2 by depositing larger amounts of biomass carbon into the soil.Cape and Trade, carbon, farm management, Environmental Economics and Policy, Farm Management, Q18, Q28, Q54, Q56,

    Robust sound event detection in bioacoustic sensor networks

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    Bioacoustic sensors, sometimes known as autonomous recording units (ARUs), can record sounds of wildlife over long periods of time in scalable and minimally invasive ways. Deriving per-species abundance estimates from these sensors requires detection, classification, and quantification of animal vocalizations as individual acoustic events. Yet, variability in ambient noise, both over time and across sensors, hinders the reliability of current automated systems for sound event detection (SED), such as convolutional neural networks (CNN) in the time-frequency domain. In this article, we develop, benchmark, and combine several machine listening techniques to improve the generalizability of SED models across heterogeneous acoustic environments. As a case study, we consider the problem of detecting avian flight calls from a ten-hour recording of nocturnal bird migration, recorded by a network of six ARUs in the presence of heterogeneous background noise. Starting from a CNN yielding state-of-the-art accuracy on this task, we introduce two noise adaptation techniques, respectively integrating short-term (60 milliseconds) and long-term (30 minutes) context. First, we apply per-channel energy normalization (PCEN) in the time-frequency domain, which applies short-term automatic gain control to every subband in the mel-frequency spectrogram. Secondly, we replace the last dense layer in the network by a context-adaptive neural network (CA-NN) layer. Combining them yields state-of-the-art results that are unmatched by artificial data augmentation alone. We release a pre-trained version of our best performing system under the name of BirdVoxDetect, a ready-to-use detector of avian flight calls in field recordings.Comment: 32 pages, in English. Submitted to PLOS ONE journal in February 2019; revised August 2019; published October 201

    Technical Bulletins: Good Service Request Systems Keep Customers Happy (2006)

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    Automated service request systems are proven to be cost-effective, labor-saving devices that greatly enhance management efficiency

    Good Service Requests Keep Customers Happy (2009)

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    Automated service request systems are proven to be cost-effective, labor-saving devices that greatly enhance management efficiency. By using the chief components outlined in this report, your city can develop an efficient automated request system

    Good Service Requests Keep Customers Happy (2012)

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    Automated service request systems are proven to be cost-effective, labor-saving devices that greatly enhance management efficiency. By using the chief components outlined in this report, your city can develop an efficient automated request system

    Asia/Pacific

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    Gender differences in ADHD adults during clinical trials with atomoxetine

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    posterIntroduction: Patients with ADHD exhibit several consistent gender differences, a male preponderance and more males with externalizing disorders (conduct and oppositional defiant disorder). Objective: To examine gender differences in a very large clinical trial of adults with ADHD. Methods: Data from two identical placebo-controlled studies of atomoxetine in adult ADHD using 535 subjects at 31 sites were combined1. The studies lasted 8 weeks and both showed positive medication-placebo differences. Most current Axis-I diagnoses were exclusionary criteria. Results: The male/female ratio of this self-referred population was 2.4:1, lower than in child studies2. In contrast to a predominance of an inattentive ADHD diagnosis subtype in female children, these adult females were more frequently combined type versus the males. Females were rated as more impaired on every measure of ADHD symptoms including total CAARS-INV, total WRAADDS3, and subscales of both measures. Females were rated as having more emotional symptoms on the WRAADDS emotional dimension, lifetime SCID-P psychiatric diagnoses, HAM-A, and HAM-D. Females exhibited significantly greater improvement on the WRAADDS emotional dimension but not on similar items in the Psychological Well-Being Scale. There were no significant gender by treatment effects in the CAARS-INV or CGI-S scores. Conclusion: These females with ADHD displayed significantly greater ADHD symptoms and emotional impairment on multiple measures. On the WRAADDS emotional dimension they responded better to treatment, than their male counterparts. Past research shows that ADHD is much more common in males particularly in pediatric samples. Children exhibit few gender differences on a consistent basis except in the area of associated symptoms. The present study addresses whether ADHD adults displayed gender differences at screening or in treatment response using data from the largest studies ever conducted in ADHD adults

    Patient-Specific Fetal Dose Determination for Multi-Target Gamma Knife Radiosurgery: Computational Model and Case Report.

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    A 42-year-old woman at 29 weeks gestation via in vitro fertilization who presented with eight metastatic brain lesions received Gamma Knife stereotactic radiosurgery (GKSRS) at our institution. In this study, we report our clinical experience and a general procedure of determining the fetal dose from patient-specific treatment plans and we describe quality assurance measurements to guide the safe practice of multi-target GKSRS of pregnant patients. To estimate fetal dose pre-treatment, peripheral dose-to-focal dose ratios (PFRs) were measured in a phantom at the distance approximating the fundus of uterus. Post-treatment, fetal dose was calculated from the actual patient treatment plan. Quality assurance measurements were carried out via the extrapolation dosimetry method in a head phantom at increasing distances along the longitudinal axis. The measurements were then empirically fitted and the fetal dose was extracted from the curve. The computed and measured fetal dose values were compared with each other and associated radiation risk was estimated. Based on low estimated fetal dose from preliminary phantom measurements, the patient was accepted for GKSRS. Eight brain metastases were treated with prescription doses of 15-19 Gy over 143 min involving all collimator sizes as well as composite sector mixed shots. Direct fetal dose computation based on the actual patient's treatment plan estimated a maximum fetal dose of 0.253 cGy, which was in agreement with surface dose measurements at the level of the patient's uterine fundus during the actual treatment. Later phantom measurements also estimated fetal dose to be in the range of 0.21-0.28 cGy (dose extrapolation curve R2 = 0.998). Using the National Council on Radiation Protection and Measurements (NCRP) population-based model, we estimate the fetal risk of secondary malignancy, which is the primary toxicity after 25 weeks gestation, to be less than 0.01%. Of note, the patient delivered the baby via scheduled cesarean section at 36 weeks without complications attributable to the GKSRS procedure. GKSRS of multiple brain metastases was demonstrated to be safe and feasible during pregnancy. The applicability of a general patient-specific fetal dose determination method was also demonstrated for the first time for such a treatment
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