| 1. |
- Li, Jing-Rebecca, et al.
(författare)
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SpinDoctor : a Matlab toolbox for diffusion MRI simulation
- 2019
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- The complex transverse water proton magnetization subject to diffusion-encoding magnetic field gradient pulses in a heterogeneous medium can be modeled by the multiple compartment Bloch-Torrey partial differential equation (BTPDE). A mathematical model for the time-dependent apparent diffusion coefficient (ADC), called the H-ADC model, was obtained recently using homogenization techniques on the BTPDE. Under the assumption of negligible water exchange between compartments, the H-ADC model produces the ADC of a diffusion medium from the solution of a diffusion equation (DE) subject to a time-dependent Neumann boundary condition. This paper describes a publicly available Matlab toolbox called SpinDoctor that can be used 1) to solve the BTPDE to obtain the dMRI signal (the toolbox provides a way of robustly fitting the dMRI signal to obtain the fitted ADC); 2) to solve the DE of the H-ADC model to obtain the ADC; 3) a short-time approximation formula for the ADC is also included in the toolbox for comparison with the simulated ADC. The PDEs are solved by P 1 finite elements combined with built-in Matlab routines for solving ordinary differential equations. The finite element mesh generation is performed using an external package called Tetgen that is included in the toolbox. SpinDoctor provides built-in options of including 1) spherical cells with a nucleus; 2) cylindrical cells with a myelin layer; 3) an extra-cellular space (ECS) enclosed either a) in a box or b) in a tight wrapping around the cells; 4) deformation of canonical cells by bending and twisting. 5) permeable membranes for the BT-PDE (the H-ADC assumes negligible permeability). Built-in diffusion-encoding pulse sequences include the Pulsed Gradient Spin Echo and the Oscillating Gradient Spin Echo.
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| 2. |
- Nguyen, C. T., et al.
(författare)
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A Comprehensive Survey of Enabling and Emerging Technologies for Social Distancing : Part I Fundamentals and Enabling Technologies
- 2020
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 8, s. 153479-153507
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Tidskriftsartikel (refereegranskat)abstract
- Social distancing plays a pivotal role in preventing the spread of viral diseases illnesses such as COVID-19. By minimizing the close physical contact among people, we can reduce the chances of catching the virus and spreading it across the community. This two-part paper aims to provide a comprehensive survey on how emerging technologies, e.g., wireless and networking, artificial intelligence (AI) can enable, encourage, and even enforce social distancing practice. In this Part I, we provide a comprehensive background of social distancing including basic concepts, measurements, models, and propose various practical social distancing scenarios. We then discuss enabling wireless technologies which are especially effect- in social distancing, e.g., symptom prediction, detection and monitoring quarantined people, and contact tracing. The companion paper Part II surveys other emerging and related technologies, such as machine learning, computer vision, thermal, ultrasound, etc., and discusses open issues and challenges (e.g., privacy-preserving, scheduling, and incentive mechanisms) in implementing social distancing in practice.
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| 3. |
- Nguyen, C. T., et al.
(författare)
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A Comprehensive Survey of Enabling and Emerging Technologies for Social Distancing - Part II : Emerging Technologies and Open Issues
- 2020
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 8, s. 154209-154236
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Tidskriftsartikel (refereegranskat)abstract
- This two-part paper aims to provide a comprehensive survey on how emerging technologies, e.g., wireless and networking, artificial intelligence (AI) can enable, encourage, and even enforce social distancing practice. In Part I, an extensive background of social distancing is provided, and enabling wireless technologies are thoroughly surveyed. In this Part II, emerging technologies such as machine learning, computer vision, thermal, ultrasound, etc., are introduced. These technologies open many new solutions and directions to deal with problems in social distancing, e.g., symptom prediction, detection and monitoring quarantined people, and contact tracing. Finally, we discuss open issues and challenges (e.g., privacy-preserving, scheduling, and incentive mechanisms) in implementing social distancing in practice. As an example, instead of reacting with ad-hoc responses to COVID-19-like pandemics in the future, smart infrastructures (e.g., next-generation wireless systems like 6G, smart home/building, smart city, intelligent transportation systems) should incorporate a pandemic mode in their standard architectures/designs.
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| 4. |
- Thai, Quan Ke, et al.
(författare)
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HV1 mtDNA Reveals the High Genetic Diversity and the Ancient Origin of Vietnamese Dogs
- 2023
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Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 13:6, s. 1036-
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary This study evaluated the genetic diversity and investigated the origin of Vietnamese domestic dogs on the basis of genetic data. A total of 56 haplotypes (group of genes inherited together from a single parent), including 14 indigenous ones (two of them have not been previously reported) were observed, with some of them implying that Australian dingo and Polynesian dogs originated from Southeast Asian ones, reinforcing the theory of domestication of dogs to the south of the Yangtze River. In this study, samples from 429 dog individuals across three main regions of Vietnam (Southern Vietnam (SVN), Central Vietnam (CVN), and Northern Vietnam (NVN)) were collected to analyze the 582 bp region mtDNA HVI, so as to study the genetic diversity and to screen the rare haplotype E in the Vietnamese village dog population. Nine new haplotypes A, two new haplotypes B, and three haplotypes C were unique to Vietnam dogs, in which the new haplotypes An3, An7, Cn1, and Cn3 concerned mutations at new polymorphism sites (15,517, 15,505, 15,479, and 15,933, respectively) which have not been previously reported. The detection of haplotypes A9 and A29, and the appearance of haplotype A200 in the two individual dogs sampled support that the Southeast Asian dog is the ancestor of today's Australian dingo and Polynesian dog. The two rare haplotypes E (E1 and E4) were reconfirmed in Vietnamese dogs and discussed. This study also contributes to strengthening the theory of domestication of dogs to the south of the Yangtze River and the Southeast Asian origin of the dingo.
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| 5. |
- Vu, T. X., et al.
(författare)
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Machine Learning-Enabled Joint Antenna Selection and Precoding Design : From Offline Complexity to Online Performance
- 2021
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248.
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the performance of multi-user multiple-antenna downlink systems in which a base station (BS) serves multiple users via a shared wireless medium. In order to fully exploit the spatial diversity while minimizing the passive energy consumed by radio frequency (RF) components, the BS is equipped with M RF chains and N antennas, where M < N. Upon receiving pilot sequences to obtain the channel state information (CSI), the BS determines the best subset of M antennas for serving the users. We propose a joint antenna selection and precoding design (JASPD) algorithm to maximize the system sum rate subject to a transmit power constraint and quality of service (QoS) requirements. The JASPD overcomes the non-convexity of the formulated problem via a doubly iterative algorithm, in which an inner loop successively optimizes the precoding vectors, followed by an outer loop that tries all valid antenna subsets. Although approaching the (near) global optimality, the JASPD suffers from a combinatorial complexity, which may limit its application in real-time network operations. To overcome this limitation, we propose a learning-based antenna selection and precoding design algorithm (L-ASPA), which employs a deep neural network (DNN) to establish underlaying relations between the key system parameters and the selected antennas. The proposed L-ASPD is robust against the number of users and their locations, BS’s transmit power, as well as the small-scale channel fading. With a well-trained learning model, it is shown that the L-ASPD significantly outperforms baseline schemes based on the block diagonalization [5] and a learning-assisted solution for broadcasting systems [29] and achieves higher effective sum rate than that of the JASPA under limited processing time. In addition, we observed that the proposed L-ASPD can reduce the computation complexity by 95% while retaining more than 95% of the optimal performance.
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| 6. |
- Innocenti, Nicolas, 1986-, et al.
(författare)
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An observation of circular RNAs in bacterial RNA-seq data.
- 2015
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Circular RNAs (circRNAs) are a class of RNA with an important role in micro RNA (miRNA) regulation recently discovered in Human and various other eukaryotes as well as in archaea. Here, we have analyzed RNA-seq data obtained from Enterococcus faecalis and Escherichia coli in a way similar to previous studies performed on eukaryotes. We report observations of circRNAs in RNA-seq data that are reproducible across multiple experiments performed with different protocols or growth conditions.
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| 7. |
- Nguyen, Hoang D. T., et al.
(författare)
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On Transmission Efficiency for Wireless Broadcast Using Network Coding and Fountain Codes
- 2011
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Ingår i: IEEE COMMUNICATIONS LETTERS. - 1089-7798. ; 15:5, s. 569-571
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the benefits of applying fountain codes (FCs) in improving the transmission efficiency in broadcasting systems. Particularly, an exact expression of the transmission efficiency for wireless broadcast using FCs is derived. This derivation allows us to compare the transmission efficiency of the fountain code approach (FCA) and network coding approach (NCA) in wireless broadcast. The numerical results demonstrate that FCA achieves better performance than NCA when the number of users is large and vice versa when the number of users is small.
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| 8. |
- Nguyen, Van Dang, 1985-, et al.
(författare)
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Diffusion MRI simulation in thin-layer and thin-tube media using a discretization on manifolds
- 2019
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Ingår i: Journal of magnetic resonance. - : Academic Press. - 1090-7807 .- 1096-0856. ; 299, s. 176-187
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Tidskriftsartikel (refereegranskat)abstract
- The Bloch-Torrey partial differential equation can be used to describe the evolution of the transverse magnetization of the imaged sample under the influence of diffusion-encoding magnetic field gradients inside the MRI scanner. The integral of the magnetization inside a voxel gives the simulated diffusion MRI signal. This paper proposes a finite element discretization on manifolds in order to efficiently simulate the diffusion MRI signal in domains that have a thin layer or a thin tube geometrical structure. The variable thickness of the three-dimensional domains is included in the weak formulation established on the manifolds. We conducted a numerical study of the proposed approach by simulating the diffusion MRI signals from the extracellular space (a thin layer medium) and from neurons (a thin tube medium), comparing the results with the reference signals obtained using a standard three-dimensional finite element discretization. We show good agreements between the simulated signals using our proposed method and the reference signals for a wide range of diffusion MRI parameters. The approximation becomes better as the diffusion time increases. The method helps to significantly reduce the required simulation time, computational memory, and difficulties associated with mesh generation, thus opening the possibilities to simulating complicated structures at low cost for a better understanding of diffusion MRI in the brain.
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| 9. |
- Nour-Mohammadi, Farahnaz, et al.
(författare)
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An investigation of the photosubstitution reaction between N719-dyed nanocrystalline TiO2 particles and 4-tert-butylpyridine
- 2007
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Ingår i: Journal of Photochemistry and Photobiology A. - : Elsevier BV. - 1010-6030 .- 1873-2666. ; 187:03-feb, s. 348-355
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Tidskriftsartikel (refereegranskat)abstract
- The effect of high concentrations of the solar cell additive 4-tert-butylpyridine (4-TBP) on the stability and lifetime of the sensitizer [Ru(Hdcbpy)(2)(NCS)(2)](2-), 2(n-C4H9)(4)N+, (H(2)dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid), known as N719, has been evaluated based on kinetic data obtained from simple model experiments. In these experiments, colloidal solutions of N719-dyed nanocrystalline TiO2 particles in acetonitrile were irradiated with 532-nm laser light in the presence of 0-1 mol/l of 4-TBP. Five degradation products were identified using LC-ESIMS: the 4-tert-butylpyridine substitution product [Ru(H(2)dcbpy)(Hdcbpy)(NCS)(4-TBP)] (SP) and the products [Ru(H(2)dcbPY)(2)(NCS)(CN)], [Ru(H(2)dcbpy)(Hdcbpy)(NCS)(CH3CN)], [Ru(H(2)dcbpy)(Hdcbpy)(NCS)(H2O)] and [Ru(H(2)dcbpy)(2)(CN)(2)] (3-6). The sum of the quantum yields of the five products, Phi(deg) = (1.3 +/- 0.2) x 10(-4), was found to be independent of 4-TBP concentration. Based on this observation, a degradation mechanism was proposed, in which the reaction proceeds through the rate-determining formation of a common intermediate complex, I = [Ru-II(H(2)dcbpy)(2)(NCS)(NCS.)](+). An average degradation rate of k(deg) = 6 x 10(-3) s(-1) was obtained from the value Of Phi(deg) and the back electrontransfer rate, k(back) of the reaction TiO2 + e(-) vertical bar N719(+) -> TiO2 vertical bar N719, obtained by means of photo-induced absorption (PIA) measurements. The lifetime of the solar cell sensitizer N719 was estimated to be between 34 years, based on k(deg) and an average literature value of the regeneration rate, k(reg) = 2 x 10(6) M-1 s(-1), of the reaction between TiO2 vertical bar N719(+) and iodide. We conclude that the addition of 4-TBP to dye-sensitized solar cells (DSSC) does not decrease the lifetime of the N719 dye during normal solar cell operation at room temperature.
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