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Compressed sensing

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https://www.readbyqxmd.com/read/28718453/analysis-of-tcspc-data-a-comparative-evaluation-of-deterministic-and-probabilistic-approaches
#1
Darren Andrew Smith, Grant McKenzie, Anita C Jones, Trevor Smith
We review various methods for analysing time-resolved fluorescence data acquired using the time-correlated single photon counting (TCSPC) method in an attempt to evaluate their benefits and limitations. We have applied these methods to both experimental and simulated data. The relative merits of using deterministic approaches, such as the commonly used iterative reconvolution method, and probabilistic approaches, such as the smoothed exponential series method (SESM), the maximum entropy method (MEM) and recently proposed basis pursuit denoising (BPDN, compressed sensing) method are outlined...
July 18, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28717186/overstepping-the-upper-refractive-index-limit-to-form-ultra-narrow-photonic-nanojets
#2
Guoqiang Gu, Jun Song, Hongda Liang, Mengjie Zhao, Yue Chen, Junle Qu
In general, photonic nanojets (PNJs) occur only when the refractive index (Ri) difference between the microparticle and background media is less than 2. The minimum full width at half-maximum (FWHM) of the PNJ is ~130 nm (approximately one-third of the illumination wavelength λ = 400 nm) formed within the evanescent field region. This paper proposes and studies a method to overstep the Ri upper bound and generate ultra-narrow PNJs. Finite element method based numerical investigations and ray-optics theoretical analyses have realized ultra-narrow PNJs with FWHM as small as 114...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28715221/pressure-dependent-light-emission-of-charged-and-neutral-excitons-in-monolayer-mose2
#3
Xinpeng Fu, Fangfei Li, Jung-Fu Lin, Yuan-Bo Gong, Xiaoli Huang, Yanping Huang, Bo Han, Qiang Zhou, Tian Cui
Tailoring the excitonic properties in two-dimensional monolayer transition metal dichalcogenides (TMDs) through strain engineering is an effective means to explore their potential applications in optoelectronics and nanoelectronics. Here we report pressure-tuned photon emission of trions and excitons in monolayer MoSe2 via a diamond anvil cell (DAC) through photoluminescence measurements and theoretical calculations. Under quasi-hydrostatic compressive strain, our results show neutral (X0) and charged (X-) excitons emission of monolayer MoSe2 can be effectively tuned by alcohol mixture vs...
July 17, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28715017/multipodal-dynamic-coordination-involving-cation-%C3%AF-interactions-to-control-the-structure-of-helical-polymers
#4
Mohammad Alzubi, Sandra Arias, Iria Louzao, Emilio Quiñoá, Ricardo Riguera, Félix Freire
A precise tuning of the four possible states of a helix (P/M helical sense and stretched/compressed helical backbone) is attained by controlling the complexation between Li(+) and a poly(phenylacetylene) that bears amide, ester and phenyl ring functionalities at the pendant group. Depending on the MeOH ratio that is present as a cosolvent, different coordination sites are involved in interactions leading to complexes I-III, each one with a characteristic structure (tri-, bi-, and unipodal) and an associated helical state...
July 17, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28708178/multiple-view-diffuse-optical-tomography-system-based-on-time-domain-compressive-measurements
#5
Andrea Farina, Marta Betcke, Laura di Sieno, Andrea Bassi, Nicolas Ducros, Antonio Pifferi, Gianluca Valentini, Simon Arridge, Cosimo D'Andrea
Compressive sensing is a powerful tool to efficiently acquire and reconstruct an image even in diffuse optical tomography (DOT) applications. In this work, a time-resolved DOT system based on structured light illumination, compressive detection, and multiple view acquisition has been proposed and experimentally validated on a biological tissue-mimicking phantom. The experimental scheme is based on two digital micromirror devices for illumination and detection modulation, in combination with a time-resolved single element detector...
July 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28706270/comprehensive-multi-dimensional-mri-for-the-simultaneous-assessment-of-cardiopulmonary-anatomy-and-physiology
#6
Joseph Y Cheng, Tao Zhang, Marcus T Alley, Martin Uecker, Michael Lustig, John M Pauly, Shreyas S Vasanawala
Diagnostic testing often assesses the cardiovascular or respiratory systems in isolation, ignoring the major pathophysiologic interactions between the systems in many diseases. When both systems are assessed currently, multiple modalities are utilized in costly fashion with burdensome logistics and decreased accessibility. Thus, we have developed a new acquisition and reconstruction paradigm using the flexibility of MRI to enable a comprehensive exam from a single 5-15 min scan. We constructed a compressive-sensing approach to pseudo-randomly acquire highly subsampled, multi-dimensionally-encoded and time-stamped data from which we reconstruct volumetric cardiac and respiratory motion phases, contrast-agent dynamics, and blood flow velocity fields...
July 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28697576/sparse-view-image-reconstruction-via-total-absolute-curvature-combining-total-variation-for-x-ray-computed-tomography
#7
Zhizhong Zheng, Ailong Cai, Lei Li, Bin Yan, Fulong Le, Linyuan Wang, Guoen Hu
Sparse-view imaging is a promising scanning approach which has fast scanning rate and low-radiation dose in X-ray computed tomography (CT). Conventional L1-norm based total variation (TV) has been widely used in image reconstruction since the advent of compressive sensing theory. However, with only the first order information of the image used, the TV often generates dissatisfactory image for some applications. As is widely known, image curvature is among the most important second order features of images and can potentially be applied in image reconstruction for quality improvement...
July 7, 2017: Journal of X-ray Science and Technology
https://www.readbyqxmd.com/read/28692977/low-rank-matrix-completion-to-reconstruct-incomplete-rendering-images
#8
Ping Liu, John P Lewis, Taehyun Rhee
Path tracing provides photo-realistic rendering in many applications but intermediate previsualization often suffers from distracting noise. Since the fundamental underlying problem is insufficient samples, we exploit the coherence of the visual signal to reconstruct missing samples, using a low-rank matrix completion framework. We present novel methods to construct low rank matrices for incomplete images including missing pixel, missing sub-pixel, and multi-frame scenarios. A convolutional neural network provides fast pre-completion for initialising missing values, and subsequent weighted nuclear norm minimisation (WNNM) with a parameter adjustment strategy (PAWNNM) efficiently recovers missing values even in high frequency details...
July 3, 2017: IEEE Transactions on Visualization and Computer Graphics
https://www.readbyqxmd.com/read/28688951/non-contrast-enhanced-3d-mr-portography-within-a-breath-hold-using-compressed-sensing-acceleration-a-prospective-noninferiority-study
#9
Ayako Ono, Shigeki Arizono, Koji Fujimoto, Thai Akasaka, Rikiya Yamashita, Akihiro Furuta, Hiroyoshi Isoda, Kaori Togashi
PURPOSE: To evaluate images of non-contrast-enhanced 3D MR portography within a breath-hold (BH) using compressed sensing (CS) compared to standard respiratory-triggered (RT) sequences. MATERIALS AND METHODS: Fifty-nine healthy volunteers underwent MR portography using two sequences of balanced steady-state free-precession (bSSFP) with time-spatial labeling inversion pulses (Time-SLIP): BH bSSFP-CS and RT bSSFP. Two radiologists independently scored the diagnostic acceptability to delineate the portal branches (MPV: main portal vein; RPV: right portal vein; LPV: left portal vein; RPPV: right posterior portal vein; and P4 and P8: portal branch of segment 4 and segment 8, respectively) and the overall image quality on a four-point scale...
July 5, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28687472/development-of-an-instrumented-spinal-cord-surrogate-using-optical-fibers-a-feasibility-study
#10
Yann Facchinello, Éric Wagnac, Bora Ung, Yvan Petit, Prabin Pradhan, Louis-Marie Peyrache, Jean-Marc Mac-Thiong
In vitro replication of traumatic spinal cord injury is necessary to understand its biomechanics and to improve animal models. During a traumatic spinal cord injury, the spinal cord withstands an impaction at high velocity. In order to fully assess the impaction, the use of spinal canal occlusion sensor is necessary. A physical spinal cord surrogate is also often used to simulate the presence of the spinal cord and its surrounding structures. In this study, an instrumented physical spinal cord surrogate is presented and validated...
July 4, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28686800/accelerated-three-dimensional-multispectral-mri-with-robust-principal-component-analysis-for-separation-of-on-and-off-resonance-signals
#11
Evan Levine, Kathryn Stevens, Christopher Beaulieu, Brian Hargreaves
PURPOSE: To enable highly accelerated distortion-free MRI near metal by separating on- and off-resonance to exploit the redundancy of slice-phase encoding for the dominant on-resonance component. METHODS: Multispectral MRI techniques resolve off-resonance distortions by a combination of limited excitation bins and additional encoding. Inspired by robust principal component analysis, a novel compact representation of multispectral images as a sum of rank-one and sparse matrices corresponding to on- and off-resonance respectively is described...
July 7, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28682270/secure-fusion-estimation-for-bandwidth-constrained-cyber-physical-systems-under-replay-attacks
#12
Bo Chen, Daniel W C Ho, Guoqiang Hu, Li Yu
State estimation plays an essential role in the monitoring and supervision of cyber-physical systems (CPSs), and its importance has made the security and estimation performance a major concern. In this case, multisensor information fusion estimation (MIFE) provides an attractive alternative to study secure estimation problems because MIFE can potentially improve estimation accuracy and enhance reliability and robustness against attacks. From the perspective of the defender, the secure distributed Kalman fusion estimation problem is investigated in this paper for a class of CPSs under replay attacks, where each local estimate obtained by the sink node is transmitted to a remote fusion center through bandwidth constrained communication channels...
July 3, 2017: IEEE Transactions on Cybernetics
https://www.readbyqxmd.com/read/28682242/low-rank-enhanced-matrix-recovery-of-hybrid-time-and-frequency-data-in-fast-magnetic-resonance-spectroscopy
#13
Hengfa Lu, Xinlin Zhang, Tianyu Qiu, Jian Yang, Jiaxi Ying, Di Guo, Zhong Chen, Xiaobo Qu
GOAL: The two dimensional magnetic resonance spectroscopy (MRS) possesses many important applications in bio-engineering but suffers from long acquisition duration. Nonuniform sampling has been applied to the spatiotemporally encoded ultrafast MRS, but results in missing data in the hybrid time and frequency plane. An approach is proposed to recover this missing signal, of which enables high quality spectrum reconstruction. METHODS: The natural exponential characteristic of MRS is exploited to recover the hybrid time and frequency signal...
June 29, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28680910/compressed-sensing-magnetic-resonance-imaging-based-on-shearlet-sparsity-and-nonlocal-total-variation
#14
Ali Pour Yazdanpanah, Emma E Regentova
Compressed sensing (CS) has been utilized for acceleration of data acquisition in magnetic resonance imaging (MRI). MR images can then be reconstructed with an undersampling rate significantly lower than that required by the Nyquist sampling criterion. However, the CS usually produces images with artifacts, especially at high reduction rates. We propose a CS MRI method called shearlet sparsity and nonlocal total variation (SS-NLTV) that exploits SS-NLTV regularization. The shearlet transform is an optimal sparsifying transform with excellent directional sensitivity compared with that by wavelet transform...
April 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28680232/a-symmetric-version-of-the-generalized-alternating-direction-method-of-multipliers-for-two-block-separable-convex-programming
#15
Jing Liu, Yongrui Duan, Min Sun
This paper introduces a symmetric version of the generalized alternating direction method of multipliers for two-block separable convex programming with linear equality constraints, which inherits the superiorities of the classical alternating direction method of multipliers (ADMM), and which extends the feasible set of the relaxation factor α of the generalized ADMM to the infinite interval [Formula: see text]. Under the conditions that the objective function is convex and the solution set is nonempty, we establish the convergence results of the proposed method, including the global convergence, the worst-case [Formula: see text] convergence rate in both the ergodic and the non-ergodic senses, where k denotes the iteration counter...
2017: Journal of Inequalities and Applications
https://www.readbyqxmd.com/read/28679250/preserving-spatial-perception-in-rooms-using-direct-sound-driven-dynamic-range-compression
#16
Henrik Gert Hassager, Tobias May, Alan Wiinberg, Torsten Dau
Fast-acting hearing-aid compression systems typically distort the auditory cues involved in the spatial perception of sounds in rooms by enhancing low-level reverberant energy portions of the sound relative to the direct sound. The present study investigated the benefit of a direct-sound driven compression system that adaptively selects appropriate time constants to preserve the listener's spatial impression. Specifically, fast-acting compression was maintained for time-frequency units dominated by the direct sound while the processing of the compressor was linearized for time-frequency units dominated by reverberation...
June 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28679237/compressive-time-delay-estimation-off-the-grid
#17
Yongsung Park, Woojae Seong, Youngmin Choo
This paper describes a time delay estimation (TDE) technique using compressive sensing (CS) off the grid, which estimates the channel impulse response in a continuous time domain. The TDE can be formulated into a sparse signal reconstruction problem where the CS technique can be applied. Previous works have used standard finite dimensional CS with evenly discretized grids. However, the actual time delays will not always lie on the discrete grid, and this mismatch between the actual and discretized time delays results in reconstruction degradation...
June 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28676860/combining-acceleration-techniques-for-low-dose-x-ray-cone-beam-computed-tomography-image-reconstruction
#18
Hsuan-Ming Huang, Ing-Tsung Hsiao
BACKGROUND AND OBJECTIVE: Over the past decade, image quality in low-dose computed tomography has been greatly improved by various compressive sensing- (CS-) based reconstruction methods. However, these methods have some disadvantages including high computational cost and slow convergence rate. Many different speed-up techniques for CS-based reconstruction algorithms have been developed. The purpose of this paper is to propose a fast reconstruction framework that combines a CS-based reconstruction algorithm with several speed-up techniques...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28676724/a-mie-resonant-antenna-with-high-sensitivity-for-force-and-strain-measurement
#19
Lingling Wu, Xiaoqing Xi, Bo Li, Ji Zhou
We demonstrate the experimental and simulated performances of a Mie resonant antenna for force sensing with high sensitivity for compressive force and strain measurements inside soft materials. The proposed sensor is compatible with biological specimens and has small dimensions. It comprises a pair of dielectric cubes and an elastic layer of silicone rubber. The applied force is determined by measuring the redshift of the operating frequency when a mechanical load applied. Both simulated and experimental results demonstrate that the relationship between the frequency shift of the sensor and the applied compressive load could be fitted well using a quadratic equation with a maximum fitting error less than 17%, which enables highly sensitive telemetric force measurements to be performed inside structures by observing the operating frequency shift...
July 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28673601/femoroacetabular-impingement-causes-osteoarthritis-of-the-hip-by-migration-and-micro-instability-of-the-femoral-head
#20
Henk Eijer, Tom Hogervorst
Femoroacetabular impingement is the condition whereby parts of the proximal femur mechanically collide with the acetabular rim leading to adjacent and contrecoup acetabular damage. Evidence is growing that at least for cam impingement, and perhaps less so for pincer impingement, there is a relation to the development of osteoarthritis. It has been demonstrated that surgery for impingement can improve function and decrease pain. Intuitively, it would then make sense that surgical intervention would prevent further degeneration...
July 2017: Medical Hypotheses
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