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Bindang Xue, Yi Liu, Linyan Cui, Xiangzhi Bai, Xiaoguang Cao, Fugen Zhou
Video stabilization in atmosphere turbulent conditions is aimed at removing spatiotemporally varying distortions from video recordings. Conventional shaky video stabilization approaches do not perform effectively under turbulent circumstances due to the erratic motion common to those conditions. Using complex-valued image pyramids, we propose a method to mitigate this erratic motion in videos. First, each frame of a video is decomposed into different spatial frequencies using the Laplacian pyramid. Second, a Riesz transform is adopted to extract the local amplitude and the local phase of each sub-band...
November 28, 2016: Optics Express
Xiaole Sun, Ivan B Djordjevic, Mark A Neifeld
We investigate a multiple spatial modes based quantum key distribution (QKD) scheme that employs multiple independent parallel beams through a marine free-space optical channel over open ocean. This approach provides the potential to increase secret key rate (SKR) linearly with the number of channels. To improve the SKR performance, we describe a back-propagation mode (BPM) method to mitigate the atmospheric turbulence effects. Our simulation results indicate that the secret key rate can be improved significantly by employing the proposed BPM-based multi-channel QKD scheme...
November 28, 2016: Optics Express
Yun Zhu, Minyu Chen, Yixin Zhang, Ye Li
This study investigates the effect of the anisotropic non-Kolmogorov turbulence of the marine atmosphere on propagation of orbital angular momentum (OAM) modes carried by partially coherent modified Bessel-Gaussian (PCMBG) beams. The analytic formula of the probability density of OAM modes is derived and used to explore the evolution of the received power of the OAM mode. PCMBG beams with long wavelength, low quantum number of the OAM mode, and a high spectral degree of coherence of the source are robust for the OAM mode propagation in turbulence...
December 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Marko Jevsek, Charbel Mounayer, Tomaz Seruga
BACKGROUND: Intra-arterial treatment of aneurysms by redirecting blood flow is a newer method. The redirection is based on a significantly more densely braided wire stent. The stent wall keeps the blood in the lumen of the stent and slows down the turbulent flow in the aneurysms. Stagnation of blood in the aneurysm sac leads to the formation of thrombus and subsequent exclusion of the aneurysm from the circulation. The aim of the study was to evaluate flow diverter device Pipeline for broad neck and giant aneurysm treatment...
December 1, 2016: Radiology and Oncology
Amir Benmira, Antonia Perez-Martin, Iris Schuster, Florent Veye, Jean Triboulet, Nicolas Berron, Isabelle Aichoun, Sarah Coudray, Jérémy Laurent, Fethi Bereksi-Reguig, Michel Dauzat
AIMS: The aim of this study was to analyze the temporal relationships between pressure, flow, and Korotkoff sounds, providing clues for their comprehensive interpretation. MATERIALS AND METHODS: When measuring blood pressure in a group of 23 volunteers, we used duplex Doppler ultrasonography to assess, under the arm-cuff, the brachial artery flow, diameter changes, and local pulse wave velocity (PWV), while recording Korotkoff sounds 10 cm downstream together with cuff pressure and ECG...
November 29, 2016: Blood Pressure Monitoring
Michal P Spilak, Torben Sigsgaard, Hisamitsu Takai, Guoqiang Zhang
People spend approximately one third of their life sleeping. Exposure to pollutants in the sleep environment often leads to a variety of adverse health effects, such as development and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient air quality in the sleep environment might be a feasible method to alleviate these health symptoms. We performed full-scale laboratory measurements using a thermal manikin positioned on an experimental bed. Three ventilation settings were tested: with no filtration system operated, use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA) device...
2016: PloS One
Richard J Lozowy, David C S Kuhn, Annie A Ducas, April J Boyd
Direct numerical simulations were performed on four patient-specific abdominal aortic aneurysm (AAA) geometries and the resulting pulsatile blood flow dynamics were compared to aneurysm shape and correlated with intraluminal thrombus (ILT) deposition. For three of the cases, turbulent vortex structures impinged/sheared along the anterior wall and along the posterior wall a zone of recirculating blood formed. Within the impingement region the AAA wall was devoid of ILT and remote to this region there was an accumulation of ILT...
November 28, 2016: Cardiovascular Engineering and Technology
F Candelier, J Einarsson, B Mehlig
We compute the angular dynamics of a neutrally buoyant nearly spherical particle immersed in an unsteady fluid. We assume that the particle is small, that its translational slip velocity is negligible, and that unsteady and convective inertia are small perturbations. We derive an approximation for the torque on the particle that determines the first inertial corrections to Jeffery's equation. These corrections arise as a consequence of local vortex stretching and can be substantial in turbulence, where local vortex stretching is strong and closely linked to the irreversibility of turbulence...
November 11, 2016: Physical Review Letters
Marcello Disertori, Michela Masè, Marta Rigoni, Giandomenico Nollo, Flavia Ravelli
BACKGROUND: Heart rate turbulence (HRT) has been proposed as a candidate marker of altered autonomic tone, and some studies showed its prognostic value for both cardiac death (CD) and sudden death. Nevertheless, HRT is not currently used in the clinical practice. METHODS AND RESULTS: We performed a systematic review and meta-analysis of the predictive value of HRT for the end points of total mortality, CD, and fatal and nonfatal ventricular arrhythmias in postacute myocardial infarction and heart failure patients...
December 2016: Circulation. Arrhythmia and Electrophysiology
Zheming Tong, Bo Yang, Philip K Hopke, K Max Zhang
Initiatives to displace petroleum and climate change mitigation have driven a recent increase in space heating with biomass combustion. However, there is ample evidence that biomass combustion emits significant quantities of health damaging pollutants. We investigated the near-source micro-environmental air quality impact of a biomass-fueled combined heat and power system equipped with an electrostatic precipitator (ESP) in Syracuse, NY. Two rooftop sampling stations with PM2.5 and CO2 analyzers were established in such that one could capture the plume while the other one served as the background for comparison depending on the wind direction...
November 18, 2016: Environmental Pollution
D P Biswas, P A Tran, C Tallon, A J O'Connor
In this paper, a novel foaming methodology consisting of turbulent mixing and thermally induced phase separation (TIPS) was used to generate scaffolds for tissue engineering. Air bubbles were mechanically introduced into a chitosan solution which forms the continuous polymer/liquid phase in the foam created. The air bubbles entrained in the foam act as a template for the macroporous architecture of the final scaffolds. Wet foams were crosslinked via glutaraldehyde and frozen at -20 °C to induce TIPS in order to limit film drainage, bubble coalescence and Ostwald ripening...
November 30, 2016: Journal of Biomaterials Science. Polymer Edition
Rebecca D Blanchard, Deborah L Engle, Lisa D Howley, Shari A Whicker, Alisa Nagler
The advancement of knowledge and development of policy in the field of medical education require critical academic discourse among the most intelligent medical educators; and critical academic discourse requires coffee. In this essay, we reflect on the state of professional development conferences in the field of medical education and the rituals that surround their success. Having begun in ancient Greece, symposia were ripe with debauchery. Today, sedated by the light brown walls of hotel conference centres, symposia are more serious endeavours, engaging men and women in the sometimes turbulent waters of epistemological debate...
December 2016: Medical Education
Yahya Baykal, Yujuan Luo, Xiaoling Ji
The scintillation index of higher order laser beams is examined when such beams propagate in anisotropic atmospheric turbulence. Anisotropy is introduced through non-Kolmogorov atmospheric turbulence. The scintillation index results are obtained by employing the Rytov method solution; thus the results are valid for weak anisotropic atmospheric turbulence and for horizontal links. Variations in the scintillations are shown for various higher order laser modes against the changes in the optical source size, power law exponent of anisotropic non-Kolmogorov spectrum, anisotropic factors, and link length...
November 20, 2016: Applied Optics
Zina Abu-Almaalie, Zabih Ghassemlooy, Manav R Bhatnagar, Hoa Le-Minh, Nauman Aslam, Shien-Kuei Liaw, It Ee Lee
Physical layer network coding (PNC) improves the throughput in wireless networks by enabling two nodes to exchange information using a minimum number of time slots. The PNC technique is proposed for two-way relay channel free space optical (TWR-FSO) communications with the aim of maximizing the utilization of network resources. The multipair TWR-FSO is considered in this paper, where a single antenna on each pair seeks to communicate via a common receiver aperture at the relay. Therefore, chip interleaving is adopted as a technique to separate the different transmitted signals at the relay node to perform PNC mapping...
November 20, 2016: Applied Optics
Zheming Li, Joakim Rosell, Marcus Aldén, Mattias Richter
Spatially and temporally resolved measurements are of great importance in turbulent premixed flame studies, especially when investigating rapid processes such as when flame local extinction, re-ignition, or flashback occur in a reacting flow. Here, an experimental approach for simultaneously probing two different species at high frame rates (50 kHz) is presented by employing a multi-YAG laser system. The laser radiation at 355 nm generated by a multi-YAG laser system was split into two beam paths: one beam for exciting formaldehyde and the other for pumping an optical parametric oscillator (OPO)...
November 18, 2016: Applied Spectroscopy
Kartik Jain, Geir Ringstad, Per-Kristian Eide, Kent-André Mardal
Obstruction to the cerebrospinal fluid (CSF) outflow caused by the herniation of cerebellar tonsils as a result of Chiari malformation type I leads to altered CSF hydrodynamics. This contribution explores the minutest characteristics of the CSF hydrodynamics in cervical subarachnoid spaces (SAS) of a healthy subject and two Chiari patients by performing highly resolved direct numerical simulation. The Lattice Boltzmann method is used for the simulations due to its scalability on modern supercomputers that allow us to simulate up to  ∼ 10(9) cells while resolving the Kolmogorov microscales...
November 10, 2016: International Journal for Numerical Methods in Biomedical Engineering
Guilherme Lopes, Eduardo Bock, Luben Gómez
Scientific and technological advances in blood pump developments have been driven by their importance in cardiac patient treatments and in the expansion of life quality in assisted people. To improve and optimize the design and development, numerical tools were incorporated into the analyses of these mechanisms and have become indispensable in their advances. This study analyzes the flow behavior with low impeller Reynolds number, for which there is no consensus on the full development of turbulence in ventricular assist devices (VAD)...
November 8, 2016: Artificial Organs
Patrick Vrancken, Martin Wirth, Gerhard Ehret, Hervé Barny, Philippe Rondeau, Henk Veerman
A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture, it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuation measurement and is thus independent of backscatter from hydrometeors and aerosol particles...
November 10, 2016: Applied Optics
Fei Liu, Xiaopeng Shao, Jie Xu, Pingli Han
We present the design of a circular polarization imager for imaging in rainy conditions, which is free from image calibration and correction before obtaining the orthogonal-state contrast image. The system employed a quarter wave plate in front of two Wollaston Prisms (WPs) to capture circularly polarized information and to acquire two orthogonally polarized images simultaneously on the charge coupled device (CCD). Along with the WPs, a reimaging part with multiaperture structure composed of two separate specialized reimaging modules, were implemented to make sure the two orthogonally polarized intensity images are exactly indicating the same scene...
November 10, 2016: Applied Optics
Yalin Zhang, Donglin Ma, Xiuhua Yuan, Zeyu Zhou
In this paper, the aperture averaged scintillation, mean signal-to-noise ratio (SNR), and average bit error rate (BER) for both flat-topped vortex hollow beams and Bessel beams propagating in a turbulent atmosphere are evaluated. Investigations are also made illustrating the variation of aperture averaged scintillation, mean SNR, and average BER against the beam type, propagation distance, and size of the receiver aperture. Compared with the flat-topped vortex hollow beams, the Bessel beams have a smaller aperture averaged scintillation, higher mean SNR, and lower average BER when the receiver aperture is relatively small under the same conditions...
November 10, 2016: Applied Optics
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