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Noise reduction

Dayna A Johnson, Jana A Hirsch, Kari A Moore, Susan Redline, Ana V Diez Roux
Although dense neighborhood built environments support increased physical activity and lower obesity, these features may also disturb sleep. Therefore, we sought to understand the association between the built environment and objectively measured sleep. From 2010 to 2013, we analyzed data from examination 5 of the Multi-Ethnic Study of Atherosclerosis, a diverse population from 6 US cities. We fit multilevel models that assessed the association between the built environment (Street Smart Walk Score, social engagement destinations, street intersections, and population density) and sleep duration or efficiency from 1-week wrist actigraphy in 1,889 individuals...
March 14, 2018: American Journal of Epidemiology
Neil E O'Connell, Louise Marston, Sally Spencer, Lorraine H DeSouza, Benedict M Wand
BACKGROUND: This is an updated version of the original Cochrane Review published in 2010, Issue 9, and last updated in 2014, Issue 4. Non-invasive brain stimulation techniques aim to induce an electrical stimulation of the brain in an attempt to reduce chronic pain by directly altering brain activity. They include repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES), transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS) and reduced impedance non-invasive cortical electrostimulation (RINCE)...
March 16, 2018: Cochrane Database of Systematic Reviews
Margarita Braunagel, Florian Ortner, Ulf Schönermarck, Antje Habicht, Andreas Schindler, Manfred Stangl, Frederik F Strobl, Maximilian Reiser, Dirk A Clevert, Christoph Trumm, Andreas Helck
RATIONALE AND OBJECTIVE: The objective of this study was to assess an optimized renal multiphase computed tomography angiography (MP-CTA) protocol regarding reduction of contrast volume. MATERIALS AND METHODS: Thirty patients underwent MP-CTA (12 phases, every 3.5 seconds, 80 kV/120 mAs) using 30 mL of contrast medium. The quality of MP-CTA was assessed quantitatively measuring vessel attenuation, image noise, and contrast-to-noise ratio. MP-CTA was evaluated qualitatively regarding depiction of vessels, cortex differentiation, and motion artifacts (grades 1-4, 1 = best)...
March 12, 2018: Academic Radiology
Junhao Liang, Anwarud Din, Tianshou Zhou
While many physical or chemical systems can be modeled by nonlinear Langevin equations (LEs), dynamical analysis of these systems is challenging in the cases of moderate and strong noise. Here we develop a linear approximation scheme, which can transform an often intractable LE into a linear set of binomial moment equations (BMEs). This scheme provides a feasible way to capture nonlinear behaviors in the sense of probability distribution and is effective even when the noise is moderate or big. Based on BMEs, we further develop a noise reduction technique, which can effectively handle tough cases where traditional small-noise theories are inapplicable...
March 14, 2018: Journal of Chemical Physics
John W Garrett, Yinsheng Li, Ke Li, Guang-Hong Chen
PURPOSE: Digital breast tomosynthesis (DBT) has been shown to somewhat alleviate the breast tissue overlapping issues of two dimensional (2D) mammography.However, the improvement in current DBT systems over mammography is still limited.Statistical image reconstruction (SIR) methods have the potential to reduce through-plane artifacts in DBT, and thus may be used to further reduce anatomical clutter. The purpose of this work was to study the impact of SIR on anatomical clutter in the reconstructed DBT image volumes...
March 15, 2018: Medical Physics
Zaineb Al-Qazwini, Zhen Yu Gordon Ko, Kalpesh Mehta, Nanguang Chen
We report an ultrahigh-speed and high-resolution line-scan spectral-domain optical coherence tomography (SD-OCT) system that integrates a number of mechanisms for improving image quality. The illumination uniformity is significantly improved by the use of a Powell lens; Phase stepping and differential reconstruction are combined to suppress autocorrelation artifacts; Nonlocal means (NLM) is employed to enhance the signal to noise ratio while minimizing motion artifacts. The system is capable of acquiring cross-sectional images at more than 3,500 B-scans per second with sensitivities between 70dB and 90dB...
March 1, 2018: Biomedical Optics Express
Yingxuan Chen, Fang-Fang Yin, Yawei Zhang, You Zhang, Lei Ren
Compressed sensing reconstruction using total variation (TV) tends to over-smooth the edge information by uniformly penalizing the image gradient. The goal of this study is to develop a novel prior contour based TV (PCTV) method to enhance the edge information in compressed sensing reconstruction for CBCT. 
 Methods: The edge information is extracted from prior planning-CT via edge detection. Prior CT is first registered with on-board CBCT reconstructed with TV method through rigid or deformable registration...
March 14, 2018: Physics in Medicine and Biology
L Alejo, E Corredoira, F Sánchez-Muñoz, C Huerga, Z Aza, R Plaza-Núñez, A Serrada, M Bret-Zurita, M Parrón, C Prieto-Areyano, G Garzón-Moll, R Madero, E Guibelalde
Objective: The new 2013/59 EURATOM Directive (ED) demands dosimetric optimisation procedures without undue delay. The aim of this study was to optimise paediatric conventional radiology exams applying the ED without compromising the clinical diagnosis. METHODS: Automatic dose management software (ADMS) was used to analyse 2678 studies of children from birth to 5 years of age, obtaining local diagnostic reference levels (DRLs) in terms of entrance surface air kerma. Given local DRL for infants and chest exams exceeded the European Commission (EC) DRL, an optimisation was performed decreasing the kVp and applying the automatic control exposure...
March 14, 2018: British Journal of Radiology
Amir Pourmorteza, Noemie Keller, Richard Chen, Albert Lardo, Henry Halperin, Marcus Y Chen, Elliot McVeigh
Resting regional wall motion abnormality (RWMA) has significant prognostic value beyond the findings of computed tomography (CT) coronary angiography. Stretch quantification of endocardial engraved zones (SQUEEZ) has been proposed as a measure of regional cardiac function. The purpose of the work reported here was to determine the effect of lowering the radiation dose on the precision of automatic SQUEEZ assessments of RWMA. Chronic myocardial infarction was created by a 2-h occlusion of the left anterior descending coronary artery in 10 swine (heart rates 80-100, ejection fraction 25-57%)...
March 13, 2018: International Journal of Cardiovascular Imaging
Leila Ibrahimi Ghavamabadi, Behzad Fouladi Dehaghi, Morteza Hesampour, Kambiz Ahmadi Angali
BACKGROUND: Use of hearing protection devices (HPDs) has become necessary when other control measures cannot reduce noise to a safe and standard level. In most countries, more effective hearing protection devices are in demand. OBJECTIVE: The aim of this study was to examine the effects of titanium dioxide (TiO2 ) nanoparticles on noise reduction efficiency in a polyvinyl chloride (PVC) earplug. METHODS: An S-60 type PVC polymer as main matrix and TiO2 with 30 nm size were used...
March 13, 2018: International Journal of Occupational Safety and Ergonomics: JOSE
Mahan Azadpour, Colette M McKay, Mario A Svirsky
Stimulation pulse rate affects current amplitude discrimination by cochlear implant (CI) users, indicated by the evidence that the JND (just noticeable difference) in current amplitude delivered by a CI electrode becomes larger at higher pulse rates. However, it is not clearly understood whether pulse rate would affect discrimination of speech intensities presented acoustically to CI processors, or what the size of this effect might be. Intensity discrimination depends on two factors: the growth of loudness with increasing sound intensity and the loudness JND (or the just noticeable loudness increment)...
March 12, 2018: Journal of the Association for Research in Otolaryngology: JARO
Morteza Modarresi Asem, Iman Sheikh Oveisi, Mona Janbozorgi
Retinal blood vessels indicate some serious health ramifications, such as cardiovascular disease and stroke. Thanks to modern imaging technology, high-resolution images provide detailed information to help analyze retinal vascular features before symptoms associated with such conditions fully develop. Additionally, these retinal images can be used by ophthalmologists to facilitate diagnosis and the procedures of eye surgery. A fuzzy noise reduction algorithm was employed to enhance color images corrupted by Gaussian noise...
July 2018: Journal of Medical Imaging
Jani Mäkinen, Erdem Sahin, Atanas Gotchev
We propose a speckle noise reduction method for generation of coherent holographic stereograms. The method employs densely sampled light field (DSLF) of the scene together with depth information acquired for each ray in the captured DSLF. Speckle reduction is achieved based on the ray separation technique where the scene is first described as a superposition of sparse sets of point sources corresponding to separated sets of rays and then the holographic reconstructions corresponding to these sparse sets of point sources are added incoherently (intensity-wise) to obtain the final reconstruction...
March 5, 2018: Optics Express
Raphael Koning, Ian C Bruce, Sam Denys, Jan Wouters
State-of-the-art hearing aids (HAs) try to overcome the deficit of poor speech intelligibility (SI) in noisy listening environments using digital noise reduction (NR) techniques. The application of time-frequency masks to the noisy sound input is a common NR technique to increase SI. The binary mask with its binary weights and the Wiener filter with continuous weights are representatives of a hard- and a soft-decision approach for time-frequency masking. In normal-hearing listeners, the ideal Wiener filter (IWF) outperforms the ideal binary mask (IBM) in terms of SI and speech quality with perfect SI even at very low signal-to-noise ratios...
March 2018: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Grant Matthews
A need to gain more confidence in computer model predictions of coming climate change has resulted in greater analysis of the quality of orbital Earth radiation budget (ERB) measurements being used today to constrain, validate, and hence improve such simulations. These studies conclude from time series analysis that for around a quarter of a century, no existing satellite ERB climate data record is of a sufficient standard to partition changes to the Earth from those of un-tracked and changing artificial instrumentation effects...
March 1, 2018: Applied Optics
Kevin Audo, Mehdi Alouini
An absorption mechanism based on second-harmonic generation (SHG) is successfully implemented as a buffer reservoir in a solid-state Er,Yb:Glass laser emitting at the telecom wavelength. We show that a slight absorption mechanism based on SHG rate conversion of 0.016% using a beta barium borate crystal enables the canceling out of the excess intensity noise at the relaxation oscillation frequency, i.e., 35 dB reduction, as well as canceling the amplified spontaneous emission beating at the free spectral range resonances of the laser lying in the gigahertz range...
March 1, 2018: Applied Optics
Farshid Mashayekhy Rad, Caroline Leck, Leopold L Ilag, Ulrika Nilsson
RATIONALE: Fatty acids are enriched in the ocean surface microlayer (SML) and have as a consequence been detected worldwide in sea spray aerosols. In searching for a relationship between the properties of the atmospheric aerosol and its ability to form cloud condensation nuclei and to promote cloud droplet formation over remote marine areas, the role of surface active fatty acids sourced from the SML is of interest to be investigated. Here is presented a fast method for profiling of major fatty acids in SML samples collected in the high Arctic (89 °N, 1 °W) in the summer of 2001...
March 9, 2018: Rapid Communications in Mass Spectrometry: RCM
Elena Prieto, María José García-Velloso, Macarena Rodríguez-Fraile, Verónica Morán, Berta García-García, Fernando Guillén, María Isabel Morales, Lidia Sancho, Iván Peñuelas, José Ángel Richter, Josep María Martí-Climent
PURPOSE: To reduce the radiation dose to patients by optimizing oncological FDG PET/CT protocols. METHODS: The baseline PET/CT protocol in our institution for oncological PET/CT examinations consisted of the administration of 5.18 MBq/kg of FDG and a CT acquisition with a reference current-time product of 120 mAs. In 2016, FDG activity was reduced to 4.44 and 3.70 MBq/kg and reference CT current-time-product was reduced to 100 and 80 mAs. 322 patients scanned with different protocols were retrospectively evaluated...
February 2018: Physica Medica: PM
Mohammad Tariqul Islam, Sk Tanvir Ahmed, Ishmam Zabir, Celia Shahnaz, Shaikh Anowarul Fattah
Photoplethysmographic (PPG) signal is getting popularity for monitoring heart rate in wearable devices because of simplicity of construction and low cost of the sensor. The task becomes very difficult due to the presence of various motion artefacts. In this study, an algorithm based on cascade and parallel combination (CPC) of adaptive filters is proposed in order to reduce the effect of motion artefacts. First, preliminary noise reduction is performed by averaging two channel PPG signals. Next in order to reduce the effect of motion artefacts, a cascaded filter structure consisting of three cascaded adaptive filter blocks is developed where three-channel accelerometer signals are used as references to motion artefacts...
February 2018: Healthcare Technology Letters
Young-Hoon Cho, Min-Yeul Ryu, Kook Jin Lee, So Jeong Park, Jun Hee Choi, Byung Chul Lee, Wung-Yeon Kim, Gyu-Tae Kim
The practical applicability of electronic devices is largely determined by the reliability of field effect transistors (FETs), necessitating constant searches for new and better-performing semiconductors. We investigated the stress-induced degradation of MoS<sub>2</sub> multilayer FETs, revealing a steady decrease of drain current by 56% from the initial value after 30 min. The drain current is recovered to the initial state when the transistor is completely turned off, indicating the roles of soft-traps in the apparent degradation...
March 7, 2018: Nanotechnology
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