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https://www.readbyqxmd.com/read/29142590/birdcage-volume-coils-and-magnetic-resonance-imaging-a-simple-experiment-for-students
#1
Dwight E Vincent, Tianhao Wang, Thalia A K Magyar, Peni I Jacob, Richard Buist, Melanie Martin
Background: This article explains some simple experiments that can be used in undergraduate or graduate physics or biomedical engineering laboratory classes to learn how birdcage volume radiofrequency (RF) coils and magnetic resonance imaging (MRI) work. For a clear picture, and to do any quantitative MRI analysis, acquiring images with a high signal-to-noise ratio (SNR) is required. With a given MRI system at a given field strength, the only means to change the SNR using hardware is to change the RF coil used to collect the image...
2017: Journal of Biological Engineering
https://www.readbyqxmd.com/read/29135951/circular-regression-in-a-dual-phase-lock-in-amplifier-for-coherent-detection-of-weak-signal
#2
Gaoxuan Wang, Serge Reboul, Jean-Bernard Choquel, Eric Fertein, Weidong Chen
Lock-in amplification (LIA) is an effective approach for recovery of weak signal buried in noise. Determination of the input signal amplitude in a classical dual-phase LIA is based on incoherent detection which leads to a biased estimation at low signal-to-noise ratio. This article presents, for the first time to our knowledge, a new architecture of LIA involving phase estimation with a linear-circular regression for coherent detection. The proposed phase delay estimate, between the input signal and a reference, is defined as the maximum-likelihood of a set of observations distributed according to a von Mises distribution...
November 14, 2017: Sensors
https://www.readbyqxmd.com/read/29135685/olivocochlear-efferent-activity-is-associated-with-the-slope-of-the-psychometric-function-of-speech-recognition-in-noise
#3
Ian B Mertes, Erin C Wilbanks, Marjorie R Leek
OBJECTIVES: The medial olivocochlear (MOC) efferent system can modify cochlear function to improve sound detection in noise, but its role in speech perception in noise is unclear. The purpose of this study was to determine the association between MOC efferent activity and performance on two speech-in-noise tasks at two signal-to-noise ratios (SNRs). It was hypothesized that efferent activity would be more strongly correlated with performance at the more challenging SNR, relative to performance at the less challenging SNR...
November 9, 2017: Ear and Hearing
https://www.readbyqxmd.com/read/29134475/synchronized-spontaneous-otoacoustic-emissions-provide-a-signal-to-noise-ratio-advantage-in-medial-olivocochlear-reflex-assays
#4
James D Lewis
Detection of medial olivocochlear-induced (MOC) changes to transient-evoked otoacoustic emissions (TEOAE) requires high signal-to-noise ratios (SNR). TEOAEs associated with synchronized spontaneous (SS) OAEs exhibit higher SNRs than TEOAEs in the absence of SSOAEs, potentially making the former well suited for MOC assays. Although SSOAEs may complicate interpretation of MOC-induced changes to TEOAE latency, recent work suggests SSOAEs are not a problem in non-latency-dependent MOC assays. The current work examined the potential benefit of SSOAEs in TEOAE-based assays of the MOC efferents...
November 13, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/29132188/-hearing-loss-and-speech-recognition-in-the-elderly
#5
Petra von Gablenz, Inga Holube
Elderly people often complain about poor speech understanding in noisy environments. In clinical practice, speech tests under noise conditions are used to examine hearing ability. The HÖRSTAT study, conducted on a population-based random sample consisting of 1903 adults, used the Goettingen Sentence Test (GÖSA) under noise conditions along with pure-tone audiometry. Hearing impairment was defined as pure-tone average at 0.5, 1, 2 and 4 kHz (PTA-4) greater than 25 dB HL in the better ear (WHO criterion). As expected, pure-tone thresholds and speech recognition thresholds (SRT) in GÖSA worsened steadily with age...
November 2017: Laryngo- Rhino- Otologie
https://www.readbyqxmd.com/read/29131445/airyscan-super-resolution-microscopy-of-mitochondrial-morphology-and-dynamics-in-living-tumor-cells
#6
Vladimir L Kolossov, Mayandi Sivaguru, Joseph Huff, Katherine Luby, Kaviamuthan Kanakaraju, H Rex Gaskins
Mitochondrial morphology is regulated by continuous fusion-and-fission events that are essential for maintaining normal function. Despite the prominence of mitochondrial function in energy generation and cell signaling, understanding of processes of fusion and fission dynamics has been hampered by the lack of high-resolution optical systems that accommodate live-cell imaging. We have examined different confocal modalities in terms of resolution and signal-to-noise ratio (SNR) in a point scanning confocal microscope with Airyscan super-resolution (AS-SR)...
November 13, 2017: Microscopy Research and Technique
https://www.readbyqxmd.com/read/29131223/enhancing-the-sensitivity-of-dna-detection-by-structurally-modified-solid-state-nanopore
#7
Kidan Lee, Hyomin Lee, Seung-Hyun Lee, Hyun-Mi Kim, Ki-Bum Kim, Sung Jae Kim
Solid-state nanopore is an ionic current-based biosensing platform, which would be a top candidate for next-generation DNA sequencing and a high-throughput drug-screening tool at single-molecular-scale resolution. There have been several approaches to enhance the sensitivity and reliability of biomolecule detection using the nanopores particularly in two aspects: signal-to-noise ratio (SNR) and translocation dwell time. In this study, an additional nano-well of 100-150 nm diameter and the aspect ratio of ∼5 called 'guide structure' was inserted in conventional silicon-substrate nanopore device to increase both SNR and dwell time...
November 13, 2017: Nanoscale
https://www.readbyqxmd.com/read/29130442/outcomes-of-hearing-aid-use-by-individuals-with-unilateral-sensorineural-hearing-loss-usnhl
#8
Charles E Bishop, Elgenaid Hamadain, Jason A Galster, Mary Frances Johnson, Christopher Spankovich, Ian Windmill
BACKGROUND: Unilateral sensorineural hearing loss (USNHL) can have a negative impact on functions associated with the advantages of balanced, binaural hearing. Although single-sided deafness, which is a complete loss of audibility in one ear, has gained increased interest in the published research, there is a gap in the literature concerning hearing aid outcomes for individuals with residual, or otherwise "aidable," hearing in the affected ear. PURPOSE: To assess hearing aid outcomes for a group of individuals with USNHL with residual, aidable function...
November 2017: Journal of the American Academy of Audiology
https://www.readbyqxmd.com/read/29129961/enhancement-of-intrinsic-optical-signal-recording-with-split-spectrum-optical-coherence-tomography
#9
Damber Thapa, Benquan Wang, Yiming Lu, Taeyoon Son, Xincheng Yao
Functional optical coherence tomography (OCT) of stimulus-evoked intrinsic optical signal (IOS) promises to be a new methodology for high-resolution mapping of retinal neural dysfunctions. However, its practical applications for non-invasive examination of retinal function have been hindered by the low signal-to-noise ratio (SNR) and small magnitude of IOSs. Split spectrum amplitude-decorrelation has been demonstrated to improve the image quality of OCT angiography. In this study, we exploited split spectrum strategy to improve the sensitivity of IOS recording...
2017: Journal of Modern Optics
https://www.readbyqxmd.com/read/29129832/multiphoton-minimal-inertia-scanning-for-fast-acquisition-of-neural-activity-signals
#10
Renaud Schuck, Mary Ann Go, Stefania Garasto, Stephanie Reynolds, Pier Luigi Dragotti, Simon Schultz
OBJECTIVE: Multi-photon laser scanning microscopy provides a powerful tool for monitoring the spatiotemporal dynamics of neural circuit activity. It is, however, intrinsically a point scanning technique. Standard raster scanning enables imaging at subcellular resolution; however, acquisition rates are limited by the size of the field of view to be scanned. Recently developed scanning strategies such as Travelling Salesman Scanning (TSS) have been developed to maximize cellular sampling rate by scanning only select regions in the field of view corresponding to locations of interest such as somata...
November 13, 2017: Journal of Neural Engineering
https://www.readbyqxmd.com/read/29128628/optogenetic-noise-photostimulation-on-the-brain-increases-somatosensory-spike-firing-responses
#11
Nayeli Huidobro, Braniff De la Torre-Valdovinos, Abraham Mendez, Mario Treviño, Oscar Arias-Carrion, Fermin Chavez, Ranier Gutierrez, Elias Manjarrez
We examined whether the optogenetic noise-photostimulation (ONP) of the barrel cortex (BC) of anesthetized Thy1-ChR2-YFP transgenic mice increases the neuronal multiunit-activity response evoked by whisker mechanical stimulation (whisker-evoked MUA). In all transgenic mice, we found that the signal-to-noise ratio (SNR) of such whisker-evoked MUA signals exhibited an inverted U-like shape as a function of the ONP level. Numerical simulations of a ChR2-expressing neuron model qualitatively support our experimental data...
November 9, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/29127944/an-experimental-validation-of-a-bayesian-model-for-quantification-in-nmr-spectroscopy
#12
Yevgen Matviychuk, Erik von Harbou, Daniel J Holland
The traditional peak integration method for quantitative analysis in nuclear magnetic resonance (NMR) spectroscopy is inherently limited by its ability to resolve overlapping peaks and is susceptible to noise. The alternative model-based approaches not only extend quantification capabilities to these challenging examples but also provide a means for automation of the entire process of NMR data analysis. In this paper, we present a general model for an NMR signal that, in a principled way, takes into account the effects of chemical shifts, relaxation, lineshape imperfections, phasing, and baseline distortions...
October 23, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/29117099/field-tests-of-a-portable-mems-gravimeter
#13
Richard P Middlemiss, Steven G Bramsiepe, Rebecca Douglas, James Hough, Douglas J Paul, Sheila Rowan, Giles D Hammond
Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5...
November 8, 2017: Sensors
https://www.readbyqxmd.com/read/29116960/image-quality-and-geometric-distortion-of-modern-diffusion-weighted-imaging-sequences-in-magnetic-resonance-imaging-of-the-prostate
#14
Daniel Stocker, Andrei Manoliu, Anton S Becker, Borna K Barth, Daniel Nanz, Markus Klarhöfer, Olivio F Donati
PURPOSE: The aim of this study was to compare qualitative and quantitative image quality and geometric distortion of 4 magnetic resonance diffusion-weighted imaging (DWI) sequences of the prostate using comparable imaging parameters and similar acquisition times. METHODS AND MATERIALS: Axial T2-weighted turbo spin echo images and axial DWI echo-planar imaging (EPI) sequences, including single-shot spin-echo (ss-EPI), readout-segmented multishot (rs-EPI), selective excitation-reduced field of view (sTX-EPI), and prototype single-shot technique applying slice-specific shimming (iShim-EPI) sequences, were acquired at 3 T in 10 healthy volunteers (mean age, 26...
November 8, 2017: Investigative Radiology
https://www.readbyqxmd.com/read/29114176/detecting-triple-vessel-disease-with-cadmium-zinc-telluride-based-single-photon-emission-computed-tomography-using-the-intensity-signal-to-noise-ratio-between-rest-and-stress-studies
#15
Yu-Hua Dean Fang, Tzu-Pei Su, Chi-Jen Chang, Kung-Chu Ho, May Su, Tzu-Chen Yen
The purpose of this study was to investigate if a novel parameter, the stress-to-rest ratio of the signal-to-noise ratio (RSNR) obtained with a cadmium zinc telluride (CZT) SPECT scanner, could be used to distinguish triple-vessel disease (TVD) patients. Methods. One hundred and two patients with suspected coronary artery disease were retrospectively involved. Each subject underwent a Tl-201 SPECT scan and subsequent coronary angiography. Subjects were separated into TVD (n = 41) and control (n = 61) groups based on coronary angiography results using 50% as the stenosis cutoff...
2017: Contrast Media & Molecular Imaging
https://www.readbyqxmd.com/read/29111643/kiwifruit-like-persistent-luminescent-nanoparticles-with-high-performance-and-in-situ-activable-near-infrared-persistent-luminescence-for-long-term-in-vivo-bioimaging
#16
Xia-Hui Lin, Liang Song, Shan Chen, Xiao-Feng Chen, Jing-Jing Wei, Jingying Li, Guoming Huang, Huang-Hao Yang
Persistent luminescence nanoparticles (PLNPs) have great potential for bioimaging because they can eliminate the tissue autofluorescence and improve the signal-to-noise ratio significantly. High-temperature calcination is a necessary process for the PLNPs to achieve high luminescence intensity and long afterglow time. However, high-temperature calcination usually results in uncontrollable morphology and poor homogeneity of PLNPs, which greatly limit their applications. Therefore, there is still a high demand to find a suitable method for synthesizing PLNPs with high luminescence intensity and long afterglow time while maintaining their monodispersed morphology...
November 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29111022/association-of-freezing-of-gait-with-nigral-iron-accumulation-in-patients-with-parkinson-s-disease
#17
Rajini M Naduthota, Arush Arun Honnedevasthana, Abhishek Lenka, Jitender Saini, Sairam Geethanath, Rose Dawn Bharath, Rita Christopher, Ravi Yadav, Arun Kumar Gupta, Pramod Kumar Pal
BACKGROUND AND PURPOSE: The objective of this work was to investigate whether patients with and without freezing of gait (FOG) in Parkinson's disease (PD) have differences in iron accumulation in substantia nigra using R2* relaxometry. MATERIALS AND METHODS: This study included seventeen PD patients with FOG [FOG (+)], equal number of age and gender matched patients without FOG [FOG (-)] and 34 healthy controls (HC). T2* images were obtained from a 3-Tesla MRI system using multi-echo sequence...
November 15, 2017: Journal of the Neurological Sciences
https://www.readbyqxmd.com/read/29110717/bayesian-intravoxel-incoherent-motion-parameter-mapping-in-the-human-heart
#18
Georg R Spinner, Constantin von Deuster, Kerem C Tezcan, Christian T Stoeck, Sebastian Kozerke
BACKGROUND: Intravoxel incoherent motion (IVIM) imaging of diffusion and perfusion in the heart suffers from high parameter estimation error. The purpose of this work is to improve cardiac IVIM parameter mapping using Bayesian inference. METHODS: A second-order motion-compensated diffusion weighted spin-echo sequence with navigator-based slice tracking was implemented to collect cardiac IVIM data in early systole in eight healthy subjects on a clinical 1.5 T CMR system...
November 6, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/29110240/manipulating-transmit-and-receive-sensitivities-of-radiofrequency-surface-coils-using-shielded-and-unshielded-high-permittivity-materials
#19
Manushka V Vaidya, Cem M Deniz, Christopher M Collins, Daniel K Sodickson, Riccardo Lattanzi
OBJECTIVE: To use high-permittivity materials (HPM) positioned near radiofrequency (RF) surface coils to manipulate transmit/receive field patterns. MATERIALS AND METHODS: A large HPM pad was placed below the RF coil to extend the field of view (FOV). The resulting signal-to-noise ratio (SNR) was compared with that of other coil configurations covering the same FOV in simulations and experiments at 7 T. Transmit/receive efficiency was evaluated when HPM discs with or without a partial shield were positioned at a distance from the coil...
November 6, 2017: Magma
https://www.readbyqxmd.com/read/29110049/diagnostic-accuracy-of-low-dose-versus-ultra-low-dose-ct-for-lumbar-disc-disease-and-facet-joint-osteoarthritis-in-patients-with-low-back-pain-with-mri-correlation
#20
Sun Hwa Lee, Seong Jong Yun, Hyeon Hwan Jo, Dong Hyeon Kim, Jae Gwang Song, Yong Sung Park
OBJECTIVE: To compare the image quality, radiation dose, and diagnostic performance between low-dose (LD) and ultra-low-dose (ULD) lumbar-spine (L-spine) CT with iterative reconstruction (IR) for patients with chronic low back pain (LBP). METHODS: In total, 260 patients with chronic LBP who underwent L-spine CT between November 2015 and September 2016 were prospectively enrolled. Of these, 143 underwent LD-CT with IR and 117 underwent ULD-CT with IR. The patients were divided according to their body mass index (BMI) into BMI1 (<22...
November 6, 2017: Skeletal Radiology
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