scholarly journals Assessment of the Use of Multi-Channel Organic Electrodes to Record ENG on Small Nerves: Application to Phrenic Nerve Burst Detection

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5594
Author(s):  
Yvan Avdeew ◽  
Victor Bergé-Laval ◽  
Virginie Le Le Rolle ◽  
Gabriel Dieuset ◽  
David Moreau ◽  
...  
Keyword(s):  
Phrenic Nerve ◽  
Gold Standard ◽  
Closed Loop ◽  
Signal To Noise Ratio ◽  
Control Variable ◽  
Roc Curves ◽  
Physiological Control ◽  
Potential Control ◽  
Channel Electrode ◽  
Organic Electrodes

Effective closed-loop neuromodulation relies on the acquisition of appropriate physiological control variables and the delivery of an appropriate stimulation signal. In particular, electroneurogram (ENG) data acquired from a set of electrodes applied at the surface of the nerve may be used as a potential control variable in this field. Improved electrode technologies and data processing methods are clearly needed in this context. In this work, we evaluated a new electrode technology based on multichannel organic electrodes (OE) and applied a signal processing chain in order to detect respiratory-related bursts from the phrenic nerve. Phrenic ENG (pENG) were acquired from nine Long Evans rats in situ preparations. For each preparation, a 16-channel OE was applied around the phrenic nerve’s surface and a suction electrode was applied to the cut end of the same nerve. The former electrode provided input multivariate pENG signals while the latter electrode provided the gold standard for data analysis. Correlations between OE signals and that from the gold standard were estimated. Signal to noise ratio (SNR) and ROC curves were built to quantify phrenic bursts detection performance. Correlation score showed the ability of the OE to record high-quality pENG. Our methods allowed good phrenic bursts detection. However, we failed to demonstrate a spatial selectivity from the multiple pENG recorded with our OE matrix. Altogether, our results suggest that highly flexible and biocompatible multi-channel electrode may represent an interesting alternative to metallic cuff electrodes to perform nerve bursts detection and/or closed-loop neuromodulation.

Identification of Surrogate Control Variables for a Robust Active Flow Controller of an Experimental High Speed Stator Cascade

2013 ◽  
Author(s):  
S. J. Steinberg ◽  
R. King ◽  
C. Tiedemann ◽  
D. Peitsch
Keyword(s):  
Linear Combination ◽  
High Speed ◽  
Closed Loop ◽  
Signal To Noise Ratio ◽  
Control Variable ◽  
Signal To Noise ◽  
Control Variables ◽  
Noise Ratio ◽  
Flow Controller ◽  
Active Flow

Active flow control is a powerful option to ensure secure operation and enhancement of the performance of axial compressors. To achieve these goals for aerodynamically highly loaded compressor blade profiles even under disturbed conditions, the magnitude of the actuation needs to be adjusted by a closed-loop controller. To this end, sensors must be placed at some meaningful positions at the surface of the blades giving information about the flow situation inside the passages. The sensor information can then lead to surrogate control variables to close the loop. Often, good sensor positions are unknown initially and therefore chosen naively or experience-driven. To obtain more informative surrogate control variables, a different approach is chosen here. Starting with a highly instrumented blade inside a linear stator cascade, featuring 16 pressure gauges in an area which is suspected to lead to high information content with respect to detrimental flow separations at the sidewalls, a Principal Component Analysis is done. The principal components provide valuable information about where and how intensively the flow is influenced by the actuation. This is validated by comparison with the results of oil flow visualizations and wake measurements. The goal is to find a linear combination of as few sensors as possible to provide a meaningful input for the closed-loop controller. As experiments are conducted up to Ma = 0.8, the signal-to-noise ratio becomes a critical issue. For this reason, specifically weighted data are introduced here. A linear combination of sensor data is obtained, describing the main effects of the actuation with an almost linear mapping. For the given set of sensors, that linear combination achieves a maximum signal-to-noise ratio, which makes it well suited as a control variable. The practical usefulness of the control variable within a robust ℋ∞-flow controller is verified in experiments in a high speed stator cascade.

scholarly journals Screening for Intermediately Vancomycin-Susceptible and Vancomycin-Heteroresistant Staphylococcus aureus by Use of Vancomycin-Supplemented Brain Heart Infusion Agar Biplates: Defining Growth Interpretation Criteria Based on Gold Standard Confirmation

2015 ◽  
Vol 53 (11) ◽  
pp. 3543-3546 ◽  
Author(s):  
Riad Khatib ◽  
Kathleen Riederer ◽  
Mamta Sharma ◽  
Stephen Shemes ◽  
Sugantha P. Iyer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Gold Standard ◽  
Population Analysis ◽  
Area Under The Curve ◽  
Brain Heart Infusion ◽  
Roc Curves ◽  
Clinical Samples ◽  
Content Type ◽  
Interpretation Criteria ◽  
Profile Area

BHI agars supplemented with vancomycin 4 (BHI-V4) and 3 (BHI-V3) mg/liter have been proposed for screening vancomycin intermediately susceptibleStaphylococcus aureus(VISA) and heteroresistant (hVISA) phenotypes, respectively, but growth interpretation criteria have not been established. We reviewed the growth results (CFU) during population analysis profile-area under the curve (PAP-AUC) of consecutive methicillin-resistantStaphylococcus aureus(MRSA) blood isolates, which were saved intermittently between 1996 and 2012. CFU counts on BHI-V4 and BHI-V3 plates were stratified according to PAP-AUC interpretive criteria: <0.90 (susceptible [S-MRSA]), 0.90 to 1.3 (hVISA), and >1.3 (VISA). CFU cutoffs that best predict VISA and hVISA were determined with the use of receiver operating characteristic (ROC) curves. Mu3, Mu50, and methicillin-susceptibleS. aureus(MSSA) controls were included. We also prospectively evaluated manufacturer-made BHI-V3/BHI-V4 biplates for screening of 2010-2012 isolates. The PAP-AUC of 616 clinical samples was consistent with S-MRSA, hVISA, and VISA in 550 (89.3%), 48 (7.8%), and 18 (2.9%) instances, respectively. For VISA screening on BHI-V4, a cutoff of 2 CFU/droplet provided 100% sensitivity and 97.7% specificity. To distinguish VISA from hVISA, a cutoff of 16 CFU provided 83.3% sensitivity and 94.7% specificity; the specificity was lowered to 89.5% with a 12-CFU cutoff. For detecting hVISA/VISA on BHI-V3, a 2-CFU/droplet cutoff provided 98.5% sensitivity and 93.8% specificity. These results suggest that 2-CFU/droplet cutoffs on BHI-V4 and BHI-V3 best approximate VISA and hVISA gold standard confirmation, respectively, with minimal overlap in samples with borderline PAP-AUC. Simultaneous screening for VISA/hVISA on manufacturer-made BHI-V4/BHI-V3 biplates is easy to standardize and may reduce the requirement for PAP-AUC confirmation.

scholarly journals Burnout in dental students: effectiveness of different methods

2013 ◽  
Vol 42 (5) ◽  
pp. 324-329 ◽  
Author(s):  
Juliana Alvares Duarte Bonini Campos ◽  
Paula Cristina Jordani ◽  
Miriane Lucindo Zucoloto ◽  
Fernanda Salloume Sampaio Bonafé ◽  
João Maroco
Keyword(s):  
Undergraduate Students ◽  
Gold Standard ◽  
Reliability And Validity ◽  
Roc Curves ◽  
Maslach Burnout Inventory ◽  
Dental Students ◽  
Burnout Syndrome ◽  
Screening Methods ◽  
Student Survey ◽  
Adequate Reliability

OBJECTIVE: This study was proposed to estimate the effectiveness of different screening methods of the Burnout Syndrome among dental students. MATERIAL AND METHOD: The Burnout Syndrome assessment was performed using the Oldenburg Inventory-Student survey (OLBI-SS) and the Copenhagen Inventory-Student survey (CBI‑SS). The Maslach Burnout Inventory-Student survey (MBI-SS) was used as the gold standard. The psychometric properties of the instruments were measured. The second-order hierarchical model was estimated to calculate the overall scores for OLBI-SS and CBI-SS, and ROC curves were constructed and the areas were estimated (AUROC). RESULT: A total of 235 undergraduate students participated in this study. The instruments showed an adequate reliability and validity; however three questions had to be removed from OLBI-SS and one from CBI-SS. The Exhaustion dimension of OLBI-SS, and Personal Burnout and Study related Burnout of CBI-SS presented a good discriminating capacity. CONCLUSION: CBI-SS showed higher discriminating capacity, than OLBI-SS, to identify the Burnout Syndrome (DAUROC=.172 [.103-.240]; p<.05).

scholarly journals Optimal Network Reconfiguration to Reduce Power Loss Using an Initial Searching Point for Continuous Genetic Algorithm

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Thuan Thanh Nguyen ◽  
Thang Trung Nguyen ◽  
Ngoc Au Nguyen
Keyword(s):  
Genetic Algorithm ◽  
Distribution System ◽  
Power Loss ◽  
Distribution Systems ◽  
Closed Loop ◽  
Control Variable ◽  
Initial Population ◽  
Network Reconfiguration ◽  
Power Loss Reduction ◽  
Continuous Genetic Algorithm

In this paper, an effective method to determine an initial searching point (ISP) of the network reconfiguration (NR) problem for power loss reduction is proposed for improving the efficiency of the continuous genetic algorithm (CGA) to the NR problem. The idea of the method is to close each initial open switch in turn and solve power flow for the distribution system with the presence of a closed loop to choose a switch with the smallest current in the closed loop for opening. If the radial topology constraint of the distribution system is satisfied, the switch opened is considered as a control variable of the ISP. Then, ISP is attached to the initial population of CGA. The calculated results from the different distribution systems show that the proposed CGA using ISP could reach the optimal radial topology with better successful rate and obtained solution quality than the method based on CGA using the initial population generated randomly and the method based on CGA using the initial radial configuration attached to the initial population. As a result, CGA using ISP can be a favorable method for finding a more effective radial topology in operating distribution systems.

Assessment of 3D-TOF-MRA at 3.0 tesla in the characterization of the angioarchitecture of cerebral arteriovenous malformations: a preliminary study

2007 ◽  
Vol 48 (6) ◽  
pp. 678-686 ◽  
Author(s):  
J. O. Heidenreich ◽  
A. M. Schilling ◽  
F. Unterharnscheidt ◽  
R. Stendel ◽  
S. Hartlieb ◽  
...  
Keyword(s):  
Image Quality ◽  
Gold Standard ◽  
Signal To Noise Ratio ◽  
Brain Arteriovenous Malformation ◽  
3.0 Tesla ◽  
Detection Rates ◽  
Tof Mra ◽  
Preliminary Study

Background: The characterization of brain arteriovenous malformation (AVM) angioarchitecture remains rewarding in planning and predicting therapy. The increased signal-to-noise ratio at higher field strength has been found advantageous in vascular brain pathologies. Purpose: To evaluate whether 3.0T time-of-flight (TOF) magnetic resonance angiography (MRA) is superior to 1.5T TOF-MRA for the characterization of cerebral AVMs. Material and Methods: Fifteen patients with AVM underwent TOF-MRA at 3.0T and 1.5T and catheter angiography (DSA), which was used as the gold standard. Blinded readers scored image quality on a four-point scale, nidus size, and number of feeding arteries and draining veins. Results: Image quality of TOF-MRA at 3.0T was superior to 1.5T but still inferior to DSA. Evaluation of nidus size was equally good at 3.0T and 1.5T for all AVMs. In small AVMs, however, there was a tendency of size overestimation at 3.0T. MRA at 3.0T had increased detection rates for feeding arteries (+21%) and superficial (+13%) and deep draining veins (+33%) over 1.5T MRA. Conclusion: 3.0T TOF-MRA offers superior characterization of AVM angioarchitecture compared with 1.5T TOF-MRA. The image quality of MRA at both 3.0 and 1.5T is still far from equal to DSA, which remains the gold standard for characterization of AVM.

scholarly journals Design and Parameter Research of Time-Harmonic Magnetic Field Sensor Based on PDMS in Microfluidic Technology

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2022
Author(s):  
Chenzhao Bai ◽  
Hongpeng Zhang ◽  
Chengjie Wang ◽  
Lebile Ilerioluwa Joseph ◽  
Qiang Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Throughput ◽  
Signal To Noise Ratio ◽  
Control Variable ◽  
Abrasive Particle ◽  
Design Parameters ◽  
Detection Accuracy ◽  
Particle Detection ◽  
Detection Technology ◽  
Time Harmonic

In order to improve the throughput and sensitivity of the inductive metal micro-abrasive particle detection sensor, this paper uses microfluidic detection technology to design a high-throughput abrasive particle detection sensor based on PDMS (Polydimethylsiloxane). Theoretical modeling analyzes the magnetization of metal abrasive particles in the coil’s time-harmonic magnetic field, and uses COMSOL simulation to calculate the best performance parameters of the sensor. Through the experiment of the control variable method, the corresponding signal value is obtained and the signal-to-noise ratio (SNR) is calculated. The SNR value and error value are calculated, and the SNR is corrected. The detection limit of the sensor is determined to be 10 μm iron particles and 60 μm copper particles. The optimal design parameters of the 3-D solenoid coil and the frequency characteristics of the sensor are obtained. Finally, through high-throughput experiments and analysis, it was found that there was a reasonable error between the actual throughput and the theoretical throughput. The design ideas suggested in this article can not only improve the sample throughput, but also ensure the detection accuracy. This provides a new idea for the development of an inductive on-line detection method of abrasive particle technology.

Closed-loop Control of Anesthesia Using Bispectral Index

2002 ◽  
Vol 96 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Anthony R. Absalom ◽  
Nicholas Sutcliffe ◽  
Gavin N. Kenny
Keyword(s):  
Bispectral Index ◽  
Closed Loop ◽  
Control Variable ◽  
Adult Patients ◽  
Closed Loop Control ◽  
Loop Control ◽  
Set Point ◽  
Target Controlled Infusion ◽  
Performance Error ◽  
Infusion System

Background The Bispectral Index (BIS) is an electroencephalogram-derived measure of anesthetic depth. A closed-loop anesthesia system was built using BIS as the control variable, a proportional-integral-differential control algorithm, and a propofol target-controlled infusion system as the control actuator. Closed-loop performance was assessed in 10 adult patients. Methods Ten adult patients scheduled to undergo elective hip or knee surgery were enrolled. An epidural cannula was inserted, and 0.5% bupivacaine was used to provide anesthesia to T8 before general anesthesia was induced using the propofol target-controlled infusion system under manual control. After the start of surgery, when anesthesia was clinically adequate, automatic control of anesthesia was commenced using the BIS as the control variable. Adequacy of anesthesia during closed-loop control was assessed clinically and by calculating the median performance error, the median absolute performance error, and the mean offset of the control variable. Results The median performance error and the median absolute performance error were 2.2 and 8.0%, respectively. Mean offset of the BIS from the set point was 0.9. Cardiovascular parameters were stable during closed-loop control. Operating conditions were adequate in all patients but one, who began moving after 45 min of stable anesthesia. No patients reported awareness or recall of intraoperative events. In three patients, there was oscillation of the measured BIS around the set point. Conclusions The system was able to provide clinically adequate anesthesia in 9 of 10 patients. Further studies are required to determine whether control performance can be improved by alterations to the gain factors or by using an effect site-targeted, target-controlled infusion propofol system.

scholarly journals ROC Curves in Clinical Chemistry: Uses, Misuses, and Possible Solutions

2004 ◽  
Vol 50 (7) ◽  
pp. 1118-1125 ◽  
Author(s):  
Nancy A Obuchowski ◽  
Michael L Lieber ◽  
Frank H Wians
Keyword(s):  
Phase I ◽  
Sample Size ◽  
Gold Standard ◽  
Diagnostic Tests ◽  
Clinical Laboratory ◽  
Clinical Chemistry ◽  
Roc Curves ◽  
Sample Size Determination ◽  
Phase Iii ◽  
Test Accuracy

Abstract Background: ROC curves have become the standard for describing and comparing the accuracy of diagnostic tests. Not surprisingly, ROC curves are used often by clinical chemists. Our aims were to observe how the accuracy of clinical laboratory diagnostic tests is assessed, compared, and reported in the literature; to identify common problems with the use of ROC curves; and to offer some possible solutions. Methods: We reviewed every original work using ROC curves and published in Clinical Chemistry in 2001 or 2002. For each article we recorded phase of the research, prospective or retrospective design, sample size, presence/absence of confidence intervals (CIs), nature of the statistical analysis, and major analysis problems. Results: Of 58 articles, 31% were phase I (exploratory), 50% were phase II (challenge), and 19% were phase III (advanced) studies. The studies increased in sample size from phase I to III and showed a progression in the use of prospective designs. Most phase I studies were powered to assess diagnostic tests with ROC areas ≥0.70. Thirty-eight percent of studies failed to include CIs for diagnostic test accuracy or the CIs were constructed inappropriately. Thirty-three percent of studies provided insufficient analysis for comparing diagnostic tests. Other problems included dichotomization of the gold standard scale and inappropriate analysis of the equivalence of two diagnostic tests. Conclusion: We identify available software and make some suggestions for sample size determination, testing for equivalence in diagnostic accuracy, and alternatives to a dichotomous classification of a continuous-scale gold standard. More methodologic research is needed in areas specific to clinical chemistry.

scholarly journals System-Level Design Considerations for Carbon Nanotube Electromechanical Resonators

2013 ◽  
Vol 2013 ◽  
pp. 1-12
Author(s):  
Christian Kauth ◽  
Marc Pastre ◽  
Jean-Michel Sallese ◽  
Maher Kayal
Keyword(s):  
Carbon Nanotube ◽  
Large Scale ◽  
Closed Loop ◽  
Signal To Noise Ratio ◽  
Systems Design ◽  
Open Loop ◽  
System Level ◽  
Time Averaging ◽  
Domain Specific ◽  
Mechanical Sensors

Despite an evermore complete plethora of complex domain-specific semiempirical models, no succinct recipe for large-scale carbon nanotube electromechanical systems design has been formulated. To combine the benefits of these highly sensitive miniaturized mechanical sensors with the vast functionalities available in electronics, we identify a reduced key parameter set of carbon nanotube properties, nanoelectromechanical system design, and operation that steers the sensor’s performance towards system applications, based on open- and closed-loop topologies. Suspended single-walled carbon nanotubes are reviewed in terms of their electromechanical properties with the objective of evaluating orders of magnitude of the electrical actuation and detection mechanisms. Open-loop time-averaging and 1ωor 2ωmixing methods are completed by a new 4ωactuation and detection technique. A discussion on their extension to closed-loop topologies and system applications concludes the analysis, covering signal-to-noise ratio, and the capability to spectrally isolate the motional information from parasitical feedthrough by contemporary electronic read-out techniques.

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