159,192 results match your criteria 10288 nm noise


An experimental method to correct low-frequency concentric artifacts in photon counting CT.

Phys Med Biol 2021 Jul 27. Epub 2021 Jul 27.

Department of Medical Physics and Department of Radiology, University of Wisconsin-Madison, 1111 Highland Ave. Rm 1005, Madison, Wisconsin, 53705, UNITED STATES.

Large-area photon counting detectors (PCDs) are usually built by tiling multiple semiconductor panels that often have slightly different spectral responses to input x-rays. As a result of this spectral inconsistency, experimental PCD-CT images of large, human-sized objects may show high-frequency ring artifacts and low-frequency band artifacts. Due to the much larger width of the bands compared with the rings, the concentric artifact problem in PCD-CT images of human-sized objects cannot be adequately addressed by conventional CT ring correction methods. Read More

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Automated three-dimensional vessel reconstruction based on deep segmentation and bi-plane angiographic projections.

Comput Med Imaging Graph 2021 Jul 21;92:101956. Epub 2021 Jul 21.

Korea Institute of Medical Microrobotics, Gwangju, 61011, South Korea; School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea. Electronic address:

Automated three-dimensional (3D) blood vessel reconstruction to improve vascular diagnosis and therapeutics is a challenging task in which the real-time implementation of automatic segmentation and specific vessel tracking for matching artery sequences is essential. Recently, a deep learning-based segmentation technique has been proposed; however, existing state-of-the-art deep architectures exhibit reduced performance when they are employed using real in-vivo imaging because of serious issues such as low contrast and noise contamination of the X-ray images. To overcome these limitations, we propose a novel methodology composed of the de-haze image enhancement technique as pre-processing and multi-level thresholding as post-processing to be applied to the lightweight multi-resolution U-shaped architecture. Read More

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The effect of interpolating low amplitude leads on the inverse reconstruction of cardiac electrical activity.

Comput Biol Med 2021 Jul 21;136:104666. Epub 2021 Jul 21.

School of Engineering, Ulster University, Northern Ireland, UK.

Electrocardiographic imaging is an imaging modality that has been introduced recently to help in visualizing the electrical activity of the heart and consequently guide the ablation therapy for ventricular arrhythmias. One of the main challenges of this modality is that the electrocardiographic signals recorded at the torso surface are contaminated with noise from different sources. Low amplitude leads are more affected by noise due to their low peak-to-peak amplitude. Read More

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Optimal attention tuning in a neuro-computational model of the visual cortex-basal ganglia-prefrontal cortex loop.

Neural Netw 2021 Jul 14;142:534-547. Epub 2021 Jul 14.

Chemnitz University of Technology, Department of Computer Science, 09107 Chemnitz, Germany. Electronic address:

Visual attention is widely considered a vital factor in the perception and analysis of a visual scene. Several studies explored the effects and mechanisms of top-down attention, but the mechanisms that determine the attentional signal are less explored. By developing a neuro-computational model of visual attention including the visual cortex-basal ganglia loop, we demonstrate how attentional alignment can evolve based on dopaminergic reward during a visual search task. Read More

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Multi-geometric parameters Gaussian fitting algorithm for rotated elliptical beam profiling using pixel ion-chamber.

Med Phys 2021 Jul 27. Epub 2021 Jul 27.

State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China.

Purpose: A high-precision rotated elliptical beam profiling method based on pixel ion-chamber is proposed in this paper. This method aims to improve the accuracy by modelling the transverse profile of rotated beam as an ellipse with additional correlation coefficient and eliminating the fitting error due to the volume averaging effect of pixel ion-chamber.

Methods: In pencil beam scanning (PBS) proton therapy systems, the transverse beam profile model is generally represented as a standard Gaussian distribution. Read More

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Assessment of the global noise algorithm for automatic noise measurement in head CT examinations.

Med Phys 2021 Jul 27. Epub 2021 Jul 27.

Rice University, Houston, TX, USA.

Purpose: The global noise (GN) algorithm has been previously introduced as a method for automatic noise measurement in clinical CT images. Accuracy of the GN algorithm has been assessed in abdomen CT exams, but not in any other body part until now. This work assesses the GN algorithm accuracy in automatic noise measurement in head CT exams. Read More

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Evaluation of a Novel Speech-in-Noise Test for Hearing Screening: Classification Performance and Transducers Characteristics.

IEEE J Biomed Health Inform 2021 Jul 27;PP. Epub 2021 Jul 27.

One of the current gaps in teleaudiology is the lack of methods for adult hearing screening viable for use in individuals of unknown language and in varying environments. We have developed a novel automated speech-in-noise test that uses stimuli viable for use in non-native listeners. The test reliability has been demonstrated in laboratory settings and in uncontrolled environmental noise settings in previous studies. Read More

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Use of a Smartphone App for Cochlear Implant Patients With Tinnitus.

Am J Audiol 2021 Jul 27:1-12. Epub 2021 Jul 27.

Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City.

Purpose Smartphone apps for tinnitus relief are now emerging; however, research supporting their use and effectiveness is lacking. Research has shown that Tinnitus Therapy sounds intended for individuals with acoustic hearing provide relief to some patients using cochlear implants (CIs) with tinnitus. Here, we evaluated the use and acceptability of a smartphone app to help CI patients with tinnitus. Read More

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Speech Understanding in Modulated Noise and Speech Maskers as a Function of Cognitive Status in Older Adults.

Am J Audiol 2021 Jul 27:1-13. Epub 2021 Jul 27.

Department of Communication Disorders, University of Massachusetts Amherst.

Objectives The purpose of this study was to investigate the impact of different types of maskers on speech understanding as a function of cognitive status in older adults. The hypothesis tested was that individuals with a diagnosis of mild cognitive impairment (MCI) or mild dementia would perform like their age- and hearing status-matched control counterparts in modulated noise but would perform more poorly in the presence of competing speech. Design Participants ( = 39; age range: 55-77 years old) performed a speech-in-noise task and completed two cognitive screening tests and a measure of working memory. Read More

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An atlas of classifiers-a machine learning paradigm for brain MRI segmentation.

Med Biol Eng Comput 2021 Jul 27. Epub 2021 Jul 27.

The School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

We present the Atlas of Classifiers (AoC)-a conceptually novel framework for brain MRI segmentation. The AoC is a spatial map of voxel-wise multinomial logistic regression (LR) functions learned from the labeled data. Upon convergence, the resulting fixed LR weights, a few for each voxel, represent the training dataset. Read More

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Age, minimum alveolar concentration and choice of depth of sedation monitor: examining the paradox of age when using the Narcotrend monitor: A secondary analysis of an observational study.

Eur J Anaesthesiol 2021 Jul 26. Epub 2021 Jul 26.

From the Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern (DH, CS, MH, FS, HAK) and Department of General Internal Medicine, Canton Hospital Frauenfeld, Frauenfeld, Switzerland (CS).

Background: With an ageing global population, it is important to individualise titration of anaesthetics according to age and by measuring their effect on the brain. A recent study reported that during general surgery, the given concentration of volatile anaesthetics, expressed as a fraction of the minimum alveolar concentration (MAC fraction), decreases by around only 3% per age-decade, which is less than the 6% expected from age-adjusted MAC. Paradoxically, despite the excessive dosing, Bispectral index (BIS) values also increased. Read More

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The Utility of Real-Time Remote Auscultation Using a Bluetooth-Connected Electronic Stethoscope: Open-Label Randomized Controlled Pilot Trial.

JMIR Mhealth Uhealth 2021 Jul 27;9(7):e23109. Epub 2021 Jul 27.

Department of Diagnostic and Generalist Medicine, Dokkyo Medical University, Tochigi, Japan.

Background: The urgent need for telemedicine has become clear in the COVID-19 pandemic. To facilitate telemedicine, the development and improvement of remote examination systems are required. A system combining an electronic stethoscope and Bluetooth connectivity is a promising option for remote auscultation in clinics and hospitals. Read More

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Unstable Phase Response Curves Shown by Spatiotemporal Patterns in the Plant Root Circadian Clock.

J Biol Rhythms 2021 Jul 27:7487304211028440. Epub 2021 Jul 27.

Graduate School of Engineering, Osaka Prefecture University, Osaka, Japan.

Phase response curves (PRCs) play important roles in the entrainment of periodic environmental cycles. Measuring the PRC is necessary to elucidate the relationship between environmental cues and the circadian clock. Conversely, the PRCs of plant circadian clocks are unstable due to multiple factors such as biotic/abiotic noise, individual differences, changes in amplitude, growth stage, and organ/tissue specificity. Read More

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An inverse technique to identify participant-specific bone adaptation from serial CT measurements.

Int J Numer Method Biomed Eng 2021 Jul 27:e3515. Epub 2021 Jul 27.

Department of Mechanical and Manufacturing Engineering, Schulich School of Engineering, University of Calgary, Calgary, Canada.

Simulated bone adaptation is framed as an interface evolution problem. The interface is extracted from a high-resolution computed tomography (CT) image of trabecular bone microarchitecture and modified by the level set equation. A model and its parameters determine the bone adaptation rate and thus the bone structure at any future time. Read More

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Impact of femtosecond laser-assisted in situ keratomileusis on retinal ganglion cell function.

Eur J Ophthalmol 2021 Jul 27:11206721211035633. Epub 2021 Jul 27.

Novovisión Clinic, Madrid, Spain.

Purpose: To analyse the effect of femtosecond laser-assisted in situ keratomileusis (FS-LASIK) on the electrical response of retinal ganglion cells using pattern electroretinography (pERG).

Methods: This was a longitudinal, prospective, observational pilot study. We included consecutive myopic patients who underwent FS-LASIK to correct up to 6 dioptres of myopia and up to 2 dioptres of astigmatism. Read More

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Structural Analysis of Nanoscale Network Materials Using Graph Theory.

ACS Nano 2021 Jul 27. Epub 2021 Jul 27.

Many materials with remarkable properties are structured as percolating nanoscale networks (PNNs). The design of this rapidly expanding family of composites and nanoporous materials requires a unifying approach for their structural description. However, their complex aperiodic architectures are difficult to describe using traditional methods that are tailored for crystals. Read More

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Impact of four kVp combinations available in a dual-source CT on the spectral performance of abdominal imaging: A task-based image quality assessment on phantom data.

J Appl Clin Med Phys 2021 Jul 26. Epub 2021 Jul 26.

Department of medical imaging, Nîmes Medical Imaging Group, CHU Nimes, Univ Montpellier, Nimes, France.

Purpose: To compare the spectral performance of four combinations of kVp available in a third generation dual-source CT (DSCT) on abdominal imaging.

Methods: An image-quality phantom was scanned with a DSCT using four kVp pairs (tube "A" voltage/tube "B" voltage): 100/Sn150 kVp, 90/Sn150 kVp, 80/Sn150 kVp, and 70/Sn150 kVp, classic parameters and dose level for abdomen examination (CTDI : 11 mGy). The noise power spectrum (NPS) and the task-based transfer function (TTF) of two inserts were computed on virtual monochromatic images (VMIs) at 40/50/60/70 keV and for mixed, low-, and high-kVp images. Read More

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Classification of glioblastoma versus primary central nervous system lymphoma using convolutional neural networks.

Sci Rep 2021 Jul 26;11(1):15219. Epub 2021 Jul 26.

Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.

A subset of primary central nervous system lymphomas (PCNSL) are difficult to distinguish from glioblastoma multiforme (GBM) on magnetic resonance imaging (MRI). We developed a convolutional neural network (CNN) to distinguish these tumors on contrast-enhanced T-weighted images. Preoperative brain tumor MRIs were retrospectively collected among 320 patients with either GBM (n = 160) and PCNSL (n = 160) from two academic institutions. Read More

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Scattering Matrix Determination in Crystalline Materials from 4D Scanning Transmission Electron Microscopy at a Single Defocus Value.

Microsc Microanal 2021 Jul 27:1-14. Epub 2021 Jul 27.

School of Physics, University of Melbourne, Parkville, VIC3010, Australia.

Recent work has revived interest in the scattering matrix formulation of electron scattering in transmission electron microscopy as a stepping stone toward atomic-resolution structure determination in the presence of multiple scattering. We discuss ways of visualizing the scattering matrix that make its properties clear. Through a simulation-based case study incorporating shot noise, we shown how regularizing on this continuity enables the scattering matrix to be reconstructed from 4D scanning transmission electron microscopy (STEM) measurements from a single defocus value. Read More

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Signal Extraction, Transformation, and Magnification for Ultrasensitive and Specific Detection of Nucleic Acids.

Anal Chem 2021 Jul 23. Epub 2021 Jul 23.

Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, China.

Nucleic acid noises caused by the background and nonspecificity amplifications can jeopardize accurate polymerization and detection of nucleic acids, especially when they are analyzed in low copies. We hypothesize to reduce the noises by designing a system for specific signal extraction, transformation, and magnification to improve the specificity and sensitivity. Herein, by developing an extractor-trigger complex (ET-Combo) for the system, we have established isothermal and hybridizing combined amplifications: a one-pot detection system with two-step amplification coupled by ET-Combo. Read More

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A comparison of automatic and manual compensation methods for the calculation of tube currents during off-centered patient positioning with a noise-based automatic exposure control system in computed tomography.

Phys Eng Sci Med 2021 Jul 23. Epub 2021 Jul 23.

Department of Radiological Technology, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8560, Japan.

Automatic exposure control (AEC) is used to optimize the X-ray tube output during computed tomography (CT) scans. However, calculation of the tube current by AEC can be affected when a patient is not aligned with the rotational center of the X-ray tube. An automatic couch height-positioning compensation mechanism provides a corrective function when the patient is off-center. Read More

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miRAnno-network-based functional microRNA annotation.

Bioinformatics 2021 Jul 23. Epub 2021 Jul 23.

Division of Orthopedic Surgery, Schroeder Arthritis and Krembil Research Institutes, University Health Network, Toronto, Ontario, Canada.

Motivation: Functional annotation is a common part of microRNA-related research, typically carried as pathway enrichment analysis of the selected microRNA targets. Here we propose miRAnno, a fast and easy-to-use web application for microRNA annotation.

Results: miRAnno uses comprehensive molecular interaction network and random walks with restart to measure the association between microRNAs and individual pathways. Read More

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Short-Term Repeatability of in Vivo Cardiac Intravoxel Incoherent Motion Tensor Imaging in Healthy Human Volunteers.

J Magn Reson Imaging 2021 Jul 23. Epub 2021 Jul 23.

Imaging Center, Harbin Medical University Cancer Hospital, Harbin, China.

Background: Intravoxel incoherent motion (IVIM) tensor imaging is a promising technique for diagnosis and monitoring of cardiovascular diseases. Knowledge about measurement repeatability, however, remains limited.

Purpose: To evaluate short-term repeatability of IVIM tensor imaging in normal in vivo human hearts. Read More

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Modeling Antimicrobial Prescriptions in Scotland: A Spatiotemporal Clustering Approach.

Risk Anal 2021 Jul 22. Epub 2021 Jul 22.

University of Edinburgh Business School, 29 Buccleuch Place, Edinburgh, EH8 9JS, UK.

In 2016, the British government acknowledged the importance of reducing antimicrobial prescriptions to avoid the long-term harmful effects of overprescription. Prescription needs are highly dependent on the factors that have a spatiotemporal component, such as bacterial outbreaks and urban densities. In this context, density-based clustering algorithms are flexible tools to analyze data by searching for group structures and therefore identifying peer groups of GPs with similar behavior. Read More

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The effects of despeckling filters on pore size measurements in collagen scaffold micro-CT data.

J Microsc 2021 Jul 22. Epub 2021 Jul 22.

Department of Materials Science and Metallurgy, University of Cambridge, U.K.

Micro-CT is often used to assess the characteristics of porous structures such as tissue engineering scaffolds and trabecular bone. Prior to analysis micro-CT images can be thresholded and filtered to remove noise. Scaffold pore size affects mechanical properties and biological cell behaviour and is a frequently assessed parameter. Read More

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Molecular Imaging of Arterial and Venous Thrombosis.

Br J Pharmacol 2021 Jul 23. Epub 2021 Jul 23.

Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute.

Thrombosis contributes to one in four deaths worldwide and is the cause of a large proportion of mortality and morbidity. A reliable and rapid diagnosis of thrombosis will allow for immediate therapy, thereby providing significant benefits to patients. Molecular imaging is a fast-growing and captivating area of research, in both preclinical and clinical applications. Read More

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Understanding the thermodynamic properties of insect swarms.

Authors:
Andy M Reynolds

Sci Rep 2021 Jul 22;11(1):14979. Epub 2021 Jul 22.

Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.

Sinhuber et al. (Sci Rep 11:3773, 2021) formulated an equation of state for laboratory swarms of the non-biting midge Chironomus riparius that holds true when the swarms are driven through thermodynamic cycles by the application external perturbations. The findings are significant because they demonstrate the surprising efficacy of classical equilibrium thermodynamics for quantitatively characterizing and predicting collective behaviour in biology. Read More

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Weighting of Prosodic and Lexical-Semantic Cues for Emotion Identification in Spectrally Degraded Speech and With Cochlear Implants.

Ear Hear 2021 Jul 21. Epub 2021 Jul 21.

Division of Speech and Hearing Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Center for Hearing Research, Boys Town National Research Hospital, Omaha, Nebraska, USA.

Objectives: Normally-hearing (NH) listeners rely more on prosodic cues than on lexical-semantic cues for emotion perception in speech. In everyday spoken communication, the ability to decipher conflicting information between prosodic and lexical-semantic cues to emotion can be important: for example, in identifying sarcasm or irony. Speech degradation in cochlear implants (CIs) can be sufficiently overcome to identify lexical-semantic cues, but the distortion of voice pitch cues makes it particularly challenging to hear prosody with CIs. Read More

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Robust control of a cable-driven rehabilitation robot for lower and upper limbs.

ISA Trans 2021 Jul 12. Epub 2021 Jul 12.

Department of Mechanical Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran. Electronic address:

In this research, a redundant cable-driven robust rehabilitation robot has been proposed for helping and automating the proper function of the patient's lower and upper limbs in the presence of uncertainties, disturbances, noise, and time delay using a new control algorithm to derive the best tracking with the least deviations. A new joint limit avoidance path-planning method is exerted while maintaining the bounds of upper and lower angles. Also, a new robust motion controller, namely computed-torque-like controller with a variable-structure compensator was applied to the system and compared with computed-torque controller outputs. Read More

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Auditory processing in schizophrenia: Behavioural evidence of abnormal spatial awareness.

Laterality 2021 Jul 22:1-15. Epub 2021 Jul 22.

Kerman Neuroscience Research center, Kerman University of Medical Sciences, Kerman, Iran.

Spatial processing deficits are the reason for many daily life problems of schizophrenia (SCZ) patients. In this study, we aimed to examine the possibility of abnormal bias to one hemifield, in form of hemispatial neglect and extinction, in auditory modality in SCZ. Twenty-five SCZ patients and 25 healthy individuals were compared on speech tasks to study the auditory neglect and extinction, as well as an auditory localization task for studying neglect. Read More

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