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frequency compression

Olga N Milekhina, Dmitry I Nechaev, Alexander Ya Supin
The goal of the study was to assess cochlear compression when rippled-spectrum signals are perceived in noise assuming that the noise might produce both masking and confounding effects. In normal listeners, discrimination between rippled signals with and without ripple phase reversals was assessed in background noise. The signals were band-limited (0.5 oct at a - 6-dB level) rippled noise centered at 2 kHz, with a ripple density of 3.5 oct-1 . The noise (masker) was band-limited nonrippled noise centered at either 2 kHz (on-frequency masker) or 1 kHz (low-frequency masker)...
May 21, 2018: Journal of the Association for Research in Otolaryngology: JARO
Pavlo I Yatsenko, Oleg V Rybalov, Oleg I Yatsenko, Vadym M Novikov, Dmytro M Kоrol, Dmytro D Kindiy, Victor D Kindiy
OBJECTIVE: Introduction: The main causes of dysfunctional conditions of the temporomandibular joints (TMJ), are occlusal, neurogenic, orthodontic disorders. The muscular component of TMJ is determines the dynamic anatomical and functional state of the mandible Therefore, in the diagnosis of dysfunctions and understanding of their pathogenesis belongs to the electromyographic method of investigation. The aim of the work was a comparative assessment of the bioelectrical activity of the actual chewing and temporal muscles in patients with musculo-articular compressiondislocation dysfunction of the TMJ of various severity...
2018: Wiadomości Lekarskie: Organ Polskiego Towarzystwa Lekarskiego
Jantien L Vroegop, Nienke C Homans, Marc P van der Schroeff, André Goedegebure
OBJECTIVES: To investigate the possible advantage of the use of a dedicated bimodal hearing aid fitting formula, the Adaptive Phonak Digital Bimodal (APDB), compared with a frequently used standard hearing aid fitting formula, the NAL-NL2. We evaluated the effects of bimodal hearing aid fitting on provided hearing aid gain and on bimodal auditory functioning in a group of experienced bimodal cochlear implant (CI) users. A second aim of our study was to determine the effect of broadband loudness balancing on the prescribed gain of those two fitting formulas...
May 16, 2018: Ear and Hearing
Ido Barth, Nathaniel J Fisch
In its usual implementation, the Raman amplifier features only one pump carrier frequency. However, pulses with well-separated frequencies can also be Raman amplified while compressed in time. Amplification with frequency-separated pumps is shown to hold even in the highly nonlinear, pump-depletion regime, as derived through a fluid model, and demonstrated via particle-in-cell simulations. The resulting efficiency is similar to single-frequency amplifiers, but, due to the beat-wave waveform of both the pump lasers and the amplified seed pulses, these amplifiers feature higher seed intensities with a shorter spike duration...
March 2018: Physical Review. E
Amalia Maria Paschou, Maria Katsikini, Dimitrios Christofilos, John Arvanitidis, Sotirios Ves
The high pressure response of type-I collagen from bovine Achilles tendon is investigated with micro-Raman spectroscopy. Fluorinert™ and methanol-ethanol mixtures were used as pressure transmitting media (PTM) in a diamond anvil cell. The Raman spectrum of collagen is dominated by three bands centred at approximately 1450, 1660 and 2930 cm-1 , attributed to C-H deformation, C=O stretching of the peptide bond (amide-I band) and C-H stretching modes, respectively. Upon pressure increase, using Fluorinert™ as PTM, a shift towards higher frequencies of the C-H stretching and deformation peaks is observed...
May 18, 2018: FEBS Journal
Juan Carlos Bermúdez Ordoñez, Rosa María Arnaldo Valdés, Fernando Gómez Comendador
A significant challenge in global navigation satellite system (GNSS) signal processing is a requirement for a very high sampling rate. The recently-emerging compressed sensing (CS) theory makes processing GNSS signals at a low sampling rate possible if the signal has a sparse representation in a certain space. Based on CS and SVD theories, an algorithm for sampling GNSS signals at a rate much lower than the Nyquist rate and reconstructing the compressed signal is proposed in this research, which is validated after the output from that process still performs signal detection using the standard fast Fourier transform (FFT) parallel frequency space search acquisition...
May 16, 2018: Sensors
Yibo Gan, Bing Tu, Pei Li, Jixing Ye, Chen Zhao, Lei Luo, Chengmin Zhang, Zetong Zhang, Linyong Zhu, Qiang Zhou
Mesenchymal stem cell- (MSC-) based therapy is regarded as a promising tissue engineering strategy to achieve nucleus pulposus (NP) regeneration for the treatment of intervertebral disc degeneration (IDD). However, it is still a challenge to promote the biosynthesis of MSC to meet the requirement of NP regeneration. The purpose of this study was to optimize the compressive magnitude to enhance the extracellular matrix (ECM) deposition towards discogenesis of MSCs. Thus, we constructed a 3D culture model for MSCs to bear different magnitudes of compression for 7 days (5%, 10%, and 20% at the frequency of 1...
2018: Stem Cells International
Dabing Wang, Xiaonan Feng, Yujuan Han
OBJECTIVE: To study the impact of interposed abdominal pulling-pressing cardiopulmonary resuscitation (IAPP-CPR) for patients with cardiac arrest (CA). METHODS: A prospective study was conducted. A total of 122 CA patients admitted to Department of Emergency of Shandong Provincial Mining Industry Group Company Central Hospital from July 2013 to December 2017 were enrolled. They were divided into standard cardiopulmonary resuscitation (S-CPR) group (n = 62) and IAPP-CPR group (n = 60) according to order of admission...
May 2018: Zhonghua Wei Zhong Bing Ji Jiu Yi Xue
Paul Edwards, Patricia-Ann Therriault, Ira Katz
Introduction: Medical air (MA) is widely used in hospitals, often manufactured onsite by compressing external ambient air and supplied through a local network piping system. Onsite production gives rise to a risk of impurities that are governed by the same pharmacopoeia purity standards applicable to commercially produced MA. The question to be addressed in this paper is how to assess if a lack of purity poses a medical problem? Methods: The MA produced onsite at a major Canadian hospital was monitored for carbon dioxide (CO2 ) and other impurity gases at high frequency (one per minute) over a two-month period...
2018: Multidisciplinary Respiratory Medicine
Ricardo Luiz Cordioli, Laurent Brochard, Laurent Suppan, Aissam Lyazidi, François Templier, Abdo Khoury, Stephane Delisle, Dominique Savary, Jean-Christophe Richard
BACKGROUND: Recommendations regarding ventilation during cardiopulmonary resuscitation (CPR) are based on a low level of scientific evidence. We hypothesized that practices about ventilation during CPR might be heterogeneous and may differ worldwide. To address this question, we surveyed physicians from several countries on their practices during CPR. METHODS: We used a Web-based opinion survey. Links to the survey were sent by e-mail newsletters and displayed on the Web sites of medical societies involved in CPR practice from December 2013 to March 2014...
May 8, 2018: Respiratory Care
Zichuan Fan, Wentao Jiang, William M D Wright
This paper describes a completely non-contact ultrasonic method of gas flow metering using air-coupled leaky Lamb waves. To show proof of principle, a simplified representation of gas flow in a duct, comprising two separated thin isotropic plates with a gas flowing between them, has been modelled and investigated experimentally. An airborne compression wave emitted from an air-coupled capacitive ultrasonic transducer excited a leaky Lamb wave in the first plate in a non-contact manner. The leakage of this Lamb wave crossed the gas flow at an angle between the two plates as a compression wave, and excited a leaky Lamb wave in the second plate...
April 23, 2018: Ultrasonics
Hideyuki Nomura, Hideo Adachi, Tomoo Kamakura
When using high-frequency (HF) ultrasound in sonography, attenuation due to the viscosity of the medium limits the available imaging depth, and strong reflection and scattering from hard tissue, such as bone, render biological diagnosis very difficult. In order to resolve these problems, the feasibility of low-frequency (LF) parametric ultrasound imaging with high directivity was explored in the present study. A pulse compression technique was applied to chirp-modulated parametric ultrasound waves in the frequency band of 100-500 kHz generated from modulated primary ultrasound waves with a center frequency of 2...
April 23, 2018: Ultrasonics
Zhiliang Bai, Shili Chen, Lecheng Jia, Zhoumo Zeng
Embracing the fact that one can recover certain signals and images from far fewer measurements than traditional methods use, compressive sensing (CS) provides solutions to huge amounts of data collection in phased array-based material characterization. This article describes how a CS framework can be utilized to effectively compress ultrasonic phased array images in time and frequency domains. By projecting the image onto its Discrete Cosine transform domain, a novel scheme was implemented to verify the potentiality of CS for data reduction, as well as to explore its reconstruction accuracy...
May 8, 2018: Sensors
Adrian Radoń, Dariusz Łukowiec, Marek Kremzer, Jarosław Mikuła, Patryk Włodarczyk
On the basis of dielectric measurements performed in a wide temperature range (173⁻373 K), a comprehensive analysis of the dielectric and electrical properties of magnetite nanoparticles electrical conduction mechanism of compressed spherical shaped Fe₃O₄ nanoparticles was proposed. The electrical conductivity of Fe₃O₄ nanoparticles was related to two different mechanisms (correlated barrier hopping and non-overlapping small polaron tunneling mechanisms); the transition between them was smooth. Additionally, role of grains and grain boundaries with charge carrier mobility and with observed hopping mechanism was described in detail...
May 5, 2018: Materials
Ki Hwan Kim, Won-Joon Do, Sung-Hong Park
PURPOSE: The routine MRI scan protocol consists of multiple pulse sequences that acquire images of varying contrast. Since high frequency contents such as edges are not significantly affected by image contrast, down-sampled images in one contrast may be improved by high resolution (HR) images acquired in another contrast, reducing the total scan time. In this study, we propose a new deep learning framework that uses HR MR images in one contrast to generate HR MR images from highly down-sampled MR images in another contrast...
May 4, 2018: Medical Physics
Md Tauhidul Islam, Anuj Chaudhry, Songyuan Tang, Ennio Tasciotti, Raffaella Righetti
Ultrasound poroelastography aims at assessing the poroelastic behavior of biological tissues via estimation of the local temporal axial strains and effective Poisson's ratios (EPR). Currently, reliable estimation of EPR using ultrasound is a challenging task due to the limited quality of lateral strain estimation. In this paper, we propose a new two-step EPR estimation technique based on dynamic programming elastography (DPE) and Horn-Schunck (HS) optical flow estimation. In the proposed method, DPE is used to estimate the integer axial and lateral displacements while HS is used to obtain subsample axial and lateral displacements from the motion-compensated pre-compressed and post-compressed radio frequency data...
May 2018: IEEE Transactions on Medical Imaging
Aaron Belbasis, Franz Konstantin Fuss
Muscle activity and fatigue performance parameters were obtained and compared between both a smart compression garment and the gold-standard, a surface electromyography (EMG) system during high-speed cycling in seven participants. The smart compression garment, based on force myography (FMG), comprised of integrated pressure sensors that were sandwiched between skin and garment, located on five thigh muscles. The muscle activity was assessed by means of crank cycle diagrams (polar plots) that displayed the muscle activity relative to the crank cycle...
2018: Frontiers in Physiology
Enrique A Lopez-Poveda, Almudena Eustaquio-Martín
It has been recently shown that cochlear implant users could enjoy better speech reception in noise and enhanced spatial unmasking with binaural audio processing inspired by the inhibitory effects of the contralateral medial olivocochlear (MOC) reflex on compression [Lopez-Poveda, Eustaquio-Martin, Stohl, Wolford, Schatzer, and Wilson (2016). Ear Hear. 37, e138-e148]. The perceptual evidence supporting those benefits, however, is limited to a few target-interferer spatial configurations and to a particular implementation of contralateral MOC inhibition...
April 2018: Journal of the Acoustical Society of America
Saber Khalili, Miralam Mahdi
This research aims to investigate the effects of some parameters on the nonlinear dynamics of an encapsulated microbubble. In the present study, the radial behavior of an encapsulated microbubble with modified Rayleigh-Plesset equation presented by Marmottant, van der Meer, Emmer, Versluis, de Jong, Hilgenfeldt, and Lohse [J. Acoust. Soc. Am. 118(6), 3499-3505 (2005)] is solved with matlab programming software. Radial dynamics of an individual microbubble for a free and coated state and effects of the added shell are also investigated...
April 2018: Journal of the Acoustical Society of America
Jing Wang, Jingui Ma, Peng Yuan, Daolong Tang, Bingjie Zhou, Guoqiang Xie, Liejia Qian
Frequency-domain optical parametric amplification (FOPA) is a new scheme that enables extremely broadband amplification of ultraintense pulses. The spatiotemporal coupling property of signal pulses can make the coherent noise of FOPA sharply different from that of conventional OPCPA. This paper presents a first theoretical study on the coherent noise produced in a FOPA system. We reveal that the coherent noise acquires the spatiotemporal coupling, and thus distinguishes the compressed signal pulse not only in time but also in space, which allows the suppression of coherent noise via optical manipulations in the spatial domain...
April 16, 2018: Optics Express
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