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frequency compression

Erik Rössler, Carlos Mattea, Simo Saarakkala, Petri Lehenkari, Mikko Finnilä, Lassi Rieppo, Sakari Karhula, Miika T Nieminen, Siegfried Stapf
NMR experiments carried out at magnetic fields below 1 T provide new relaxation parameters unavailable with conventional clinical scanners. Contrast of T1 generally becomes larger towards low fields, as slow molecular reorientation processes dominate relaxation at the corresponding Larmor frequencies. This advantage has to be considered in the context of lower sensitivity and frequently reduced spatial resolution. The layered structure of cartilage is one example where a particularly strong variation of T1 across the tissue occurs, being affected by degenerative diseases such as osteoarthritis (OA)...
May 24, 2017: NMR in Biomedicine
Hanna Schröder, Alexandra Henke, Lina Stieger, Stefan Beckers, Henning Biermann, Rolf Rossaint, Saša Sopka
BACKGROUND: Learning and training basic life support (BLS)-especially external chest compressions (ECC) within the BLS-algorithm-are essential resuscitation training for laypersons as well as for health care professionals. The objective of this study was to evaluate the influence of learning styles on the performance of BLS and to identify whether all types of learners are sufficiently addressed by Peyton's four-step approach for BLS training. METHODS: A study group of first-year medical students (n = 334) without previous medical knowledge was categorized according to learning styles using the German Lernstilinventar questionnaire based on Kolb's Learning Styles Inventory...
2017: PloS One
Yazhou Wang, Guangsheng Li, Keith D K Luk, Yong Hu
This study aims to determine whether the time-frequency components (TFCs) of somatosensory evoked potentials (SEPs) can be used to identify the specific location of a compressive spinal cord injury using a classification technique. Waveforms of SEPs after compressive injuries at various locations (C4, C5 and C6) in rat spinal cords were decomposed into a series of TFCs using a high-resolution time-frequency analysis method. A classification method based on support vector machine (SVM) was applied to the distributions of these TFCs among different pathological locations...
May 24, 2017: Scientific Reports
Alessandro Piras, Giorgio Gatta
Piras, A and Gatta, G. Evaluation of the effectiveness of compression garments on autonomic nervous system recovery after exercise. J Strength Cond Res 31(6): 1636-1643, 2017-The aim of this investigation was to evaluate the recovery pattern of a whole-body compression garment on hemodynamic parameters and on autonomic nervous system (ANS) activity after a swimming performance. Ten young male athletes were recruited and tested in 2 different days, with and without wearing the garment during the recovery phase...
June 2017: Journal of Strength and Conditioning Research
Ai-Xia Zhang, Jiang-Tao Liu, San-Dong Guo, Hui-Chao Li
Strain engineering is a very effective method to continuously tune the electronic, topological, optical and thermoelectric properties of materials. In this work, strain-dependent phonon transport of recently-fabricated antimonene (Sb monolayers) under biaxial strain is investigated using a combination of first-principles calculations and the linearized phonon Boltzmann equation within the single-mode relaxation time approximation (RTA). It is found that the ZA dispersion of antimonene with strain less than -1% gives imaginary frequencies, which suggests that compressive strain can induce structural instability...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
Ke Li, Liang Xia, Ning Fei Liu, Fabio Nicoli, Joannis Constantinides, Christopher D'Ambrosia, Davide Lazzeri, Mathias Tremp, Ju Fang Zhang, Yi Xin Zhang
BACKGROUND: The incidence of breast cancer related lymphedema is approximately 5%. Far infrared ray (FIR) treatment can potentially reduce fluid volume and extremity circumference as well as the frequency of dermato-lymphangitis (DLA). However, there is no published data on the oncological safety of FIR and the potential for activation of any residual breast cancer cells. The aim of this study is to investigate the safety of far infrared ray (FIR) treatment of postmastectomy lymphedema, clinically and in vitro...
May 11, 2017: Journal of Photochemistry and Photobiology. B, Biology
Wei Fan, Li-Xin Guo
Very few studies have quantitatively analyzed influence of the loading frequency on time-domain vibration response of the whole lumbar spine in the presence of a physiologic compressive preload. In this study, a three-dimensional non-linear finite element model of ligamentous L1-S1 segment was developed to predict time-domain dynamic response of the whole lumbar spine to axial cyclic loading with different frequencies. A compressive follower preload of 400 N was applied to the model to simulate the physiologic compressive load...
May 10, 2017: Computers in Biology and Medicine
Mateusz Urbańczyk, Michał Nowakowski, Wiktor Koźmiński, Krzysztof Kazimierczuk
NMR relaxometry plays crucial role in studies of protein dynamics. The measurement of longitudinal and transverse relaxation rates of [Formula: see text]N is the main source of information on backbone motions. However, even the most basic approach exploiting a series of [Formula: see text]N HSQC spectra can require several hours of measurement time. Standard non-uniform sampling (NUS), i.e. random under-sampling of indirect time domain, typically cannot reduce this by more than 2-4[Formula: see text] due to relatively low "compressibility" of these spectra...
May 15, 2017: Journal of Biomolecular NMR
Anurupa Shaw, Damien Teyssieux, Vincent Laude
The measurement of the displacements caused by the propagation of a short pulse of surface acoustic waves on a solid substrate is investigated. A stabilized time-domain differential interferometer is proposed, with the surface acoustic wave (SAW) sample placed outside the interferometer. Experiments are conducted with surface acoustic waves excited by a chirped interdigital transducer on a piezoelectric lithium niobate substrate having an operational bandwidth covering the 200-400MHz frequency range and producing 10-ns pulses with 36nm maximum out-of-plane displacement...
May 10, 2017: Ultrasonics
Nicky Cullum, Zhenmi Liu
BACKGROUND: Venous leg ulcers are a type of chronic, recurring, complex wound that is more common in people aged over 65 years. Venous ulcers pose a significant burden to patients and healthcare systems. While compression therapy (such as bandages or stockings) is an effective first-line treatment, ultrasound may have a role to play in healing venous ulcers. OBJECTIVES: To determine whether venous leg ulcers treated with ultrasound heal more quickly than those not treated with ultrasound...
May 15, 2017: Cochrane Database of Systematic Reviews
Dan Z Reinstein, Glenn I Carp, Timothy J Archer, Tim Buick, Marine Gobbe, Elizabeth L Rowe, Mario Jukic, Emma Brandon, Johnny Moore, Tara Moore
PURPOSE: To evaluate outcomes of high hyperopic LASIK using the MEL 80 excimer laser (Carl Zeiss Meditec, Jena, Germany). METHODS: Retrospective analysis of 830 consecutive high hyperopic LASIK procedures using the MEL 80 excimer laser and either the VisuMax femtosecond laser (Carl Zeiss Meditec) or zero compression Hansatome microkeratome (Bausch & Lomb, Rochester, NY). Inclusion criteria were attempted hyperopic correction of +4.00 diopters [D] or higher in one axis and corrected distance visual acuity (CDVA) of 20/20 or better...
May 1, 2017: Journal of Refractive Surgery
Muhammad Arif, Muhammad Asim Ali, Muhammad Mujtaba Shaikh, Steven Freear
Non-linear frequency-modulated (NLFM) chirp coding was investigated to improve the pulse compression of the second harmonic chirp signal by reducing the range side lobe level. The problem of spectral overlap between the fundamental component and second harmonic component (SHC) was also investigated. Therefore, two methods were proposed: method I for the non-overlap condition and method II with the pulse inversion technique for the overlap harmonic condition. In both methods, the performance of the NLFM chirp was compared with that of the reference LFM chirp signals...
May 5, 2017: Ultrasound in Medicine & Biology
Caipin Li, Mingyi He
Geosynchronous Orbit Synthetic Aperture Radar (GEO SAR) has recently received increasing attention due to its ability of performing staring observations of ground targets. However, GEO SAR staring observation has an ultra-long integration time that conventional frequency domain algorithms cannot handle because of the inaccurately assumed slant range model and existing azimuth aliasing. To overcome this problem, this paper proposes an improved chirp-scaling algorithm that uses a fifth-order slant range model where considering the impact of the "stop and go" assumption to overcome the inaccuracy of the conventional slant model and a two-step processing method to remove azimuth aliasing...
May 6, 2017: Sensors
Mitchell L Wyffels, Paul J Orchard, Ryan M Shanley, Weston P Miller, Ann E Van Heest
PURPOSE: Children with Hurler syndrome (HS) develop carpal tunnel syndrome (CTS) owing to glycosaminoglycan deposition secondary to enzyme deficiency. Advancement in the treatment of the underlying enzyme deficiency now commonly includes peritransplant intravenous enzyme replacement therapy (ERT). The primary objective of this study was to determine if the use of limited ERT in addition to hematopoietic stem cell transplantation (HCT) for the treatment of children with HS reduces the incidence of surgical intervention for CTS compared with a cohort of historical controls treated with HCT alone...
May 4, 2017: Journal of Hand Surgery
Bo-Hai Wu, Xiao-Xing Kou, Ci Zhang, Yi-Mei Zhang, Zhen Cui, Xue-Dong Wang, Yan Liu, Da-Wei Liu, Yan-Heng Zhou
Mechanical tension is widely applied on the suture to modulate the growth of craniofacial bones. Deeply understanding the features of bone formation in expanding sutures could help us to improve the outcomes of clinical treatment and avoid some side effects. Although there are reports that have uncovered some biological characteristics, the regular pattern of sutural bone formation in response to expansion forces is still unknown. Our study was to investigate the shape, arrangement and orientation of new bone formation in expanding sutures and explore related clinical implications...
2017: PloS One
Weisong Liu, Zhitao Huang, Xiang Wang, Weichao Sun
In a cognitive radio sensor network (CRSN), wideband spectrum sensing devices which aims to effectively exploit temporarily vacant spectrum intervals as soon as possible are of great importance. However, the challenge of increasingly high signal frequency and wide bandwidth requires an extremely high sampling rate which may exceed today's best analog-to-digital converters (ADCs) front-end bandwidth. Recently, the newly proposed architecture called modulated wideband converter (MWC), is an attractive analog compressed sensing technique that can highly reduce the sampling rate...
May 4, 2017: Sensors
Marcus Seidel, Jonathan Brons, Gunnar Arisholm, Kilian Fritsch, Vladimir Pervak, Oleg Pronin
Peak and average power scalability is the key feature of advancing femtosecond laser technology. Today, near-infrared light sources are capable of providing hundreds of Watts of average power. These sources, however, scarcely deliver pulses shorter than 100 fs which are, for instance, highly beneficial for frequency conversion to the extreme ultraviolet or to the mid- infrared. Therefore, the development of power scalable pulse compression schemes is still an ongoing quest. This article presents the compression of 90 W average power, 190 fs pulses to 70 W, 30 fs...
May 3, 2017: Scientific Reports
Shuai Wang, Xinyu Fan, Bin Wang, Guangyao Yang, Zuyuan He
Pulse compression technique is a particularly competitive method that enables both high spatial resolution and dynamic range in coherent radar and distributed fiber sensing systems. Up to now, the frequency bandwidths of most pulse compression techniques are restricted to tens of GHz. In this paper, we propose an all-optic sub-THz-range linearly chirped optical source and a large-bandwidth detection system to characterize it. Taking advantage of the chromatic dispersion effect, ultrashort optical pulses are stretched to be ~10 ns linearly chirped pulses with sub-THz range, which yields a large time-bandwidth product of 4500, a high compression ratio of 4167 and a chirp rate of 45 GHz/ns...
May 1, 2017: Optics Express
Jan Rennies, Jakob Drefs, David Hülsmeier, Henning Schepker, Simon Doclo
In many applications in which speech is played back via a sound reinforcement system such as public address systems and mobile phones, speech intelligibility is degraded by additive environmental noise. A possible solution to maintain high intelligibility in noise is to pre-process the speech signal based on the estimated noise power at the position of the listener. The previously proposed AdaptDRC algorithm [Schepker, Rennies, and Doclo (2015). J. Acoust. Soc. Am. 138, 2692-2706] applies both frequency shaping and dynamic range compression under an equal-power constraint, where the processing is adaptively controlled by short-term estimates of the speech intelligibility index...
April 2017: Journal of the Acoustical Society of America
Jason W Stafford, Bradley D Duncan, David J Rabb
Simultaneous range compression and aperture synthesis is experimentally demonstrated with a stepped linear frequency modulated waveform and holographic aperture ladar. The resultant three-dimensional (3D) data has high resolution in the aperture synthesis dimension and is recorded using a conventional low bandwidth focal plane array. Individual cross-range field segments are coherently combined using data driven registration and phase correction methods allowing range compression to be performed without the benefit of a coherent waveform...
May 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
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