Activity

.Low dose X-ray computed tomography (LDCT) is desirable for reduced patient dose. This work develops image reconstruction methods with deep learning (DL) regularization for LDCT. Our methods are based on unrolling of proximal forward-backward splitting (PFBS) framework with data-driven image regularization via deep neural networks. In contrast with PFBS-IR that utilizes standard data fidelity updates via iterative reconstruction (IR) method, PFBS-AIR involves preconditioned data fidelity updates that fuse analytical reconstruction (AR) method and IR in a synergistic way, i.e., fused analytical and iterative reconstruction (AIR). The results suggest that DL-regularized methods (PFBS-IR and PFBSAIR) provided better reconstruction quality from conventional wisdoms (AR or IR). UNC6852 concentration In addition, owing to AIR, PFBS-AIR noticeably outperformed PFBS-IR, and another DL-based postprocessing method FBPConvNet. © 2020 Institute of Physics and Engineering in Medicine.OBJECTIVE Computational current flow models of spinal cord stimulation (SCS) are widely used in device development, clinical trial design, and patient programming. Proprietary models of varied sophistication have been developed. An open-source model with state-of-the-art precision would serve as a standard for SCS simulation. APPROACH We developed a sophisticated SCS modeling platform, named Realistic Anatomically Detailed Open-Source Spinal Cord Stimulation (RADO-SCS) model. This platform consists of realistic and detailed spinal cord and ancillary tissues anatomy derived based on prior imaging and cadaveric studies. In our finite element model of the T9-T11 spine levels, we represented the following tissues vertebrae, intervertebral disc, epidural space, epidural space vasculature, dura mater, dural sac, intraforaminal tissue, cerebrospinal fluid (CSF), whitematter, spinal cord vasculature, Lissauer’s tract, gray matter, dorsal and ventral roots and rootlets, dorsal root ganglion (DRG), sympathetic chain (trunk and ganglion), thoracic aorta and its branching, peripheral vasculature, and soft tissues (thorax). As an exemplary application to illustrate the model workflow, we simulated a bipolar SCS montage and calculated the corresponding activation thresholds for individual axons populating the spinal cord. MAIN RESULTS RADO-SCS provides state-of-the-art precision across 19 tissue compartments. The resulting model calculations of the electric fields generated in the white-matter and gray matter, and the axonal activation thresholds are broadly consistent with prior simulations. SIGNIFICANCE The RADO-SCS can be used to simulate any SCS approach with both unprecedented resolution (precision) and transparency (reproducibility). Freely-available online, the RADO-SCS will be updated continuously with version control. © 2020 IOP Publishing Ltd.This work presents a study on the controlled growth of WO3nanowires via chemical vapor deposition without catalyst, and their potential applications in visible photodetectors. The influence of growth conditions on the morphology of WO3nanowires is studied in order to understand the growth mechanism of WO3nanowires, and ultra-long (60 μm, the longest one ever reported) WO3nanowires with a spindle shape are achieved by optimizing the growth conditions. It was found that the length of WO3nanowires increases from 15 μm to 60 μm with increasing the argon carrier gas flow rate from 30 sccm to 90 sccm, and then saturates with further increasing the argon carrier gas flow rate. However, the length of WO3nanowires reduces from 60 μm to 19 μm with increasing the tube inner pressure from 2.5 Torr to 3.5 Torr. The photoconductor detectors based on WO3single nanowires present excellent device performance with a responsivity as high as 19 A/W, a detectivity as high as 1.06 × 1011Jones, and a response (rising and decay) time as short as 8 ms under the illumination of a 404 nm laser. These results indicate the great potential of WO3nanowires for applications in fabricating high performance visible photodetectors. © 2020 IOP Publishing Ltd.Two-dimensional materials with a sheet structure have excellent optical, electrical and mechanical properties, and have attracted much attention in recent years, especially In2Se3 (the N-type semiconductor compound), which has a rapid development in the fields of materials science and optical communication. In this paper, the nonlinear saturation absorption characteristics of In2Se3 are studied. The In2Se3 nanosheet dispersion can be used in ultrafast photonics applications. The nonlinear absorption is measured by power correlation method, and the modulation depth and saturation intensity are 3.8 % and 246.6 MW/cm2, respectively. More importantly, In2Se3 is used as a saturable absorber (SA) in a passively mode-locked erbium-doped fiber laser. The proposed mode-locked fiber laser is demenstrated with a center wavelength of 1529.4 nm, a fundamental frequency of 5.9 MHz, a spectral width of 3.96 nm, a pulse width of 1.38 ps, and a signal-to-noise ratio of 55 dB. For the first time, harmonic mode-locking with a high-repetition rate of 431 MHz is achieved when the pump power is 360 mW corresponding to 73rd-order harmonic mode locking. It can be seen that In2Se3 is indeed a new excellent photonic material, which can be used in fiber optic communication, SAs photonics,, laser material processing and light modulators. © 2020 IOP Publishing Ltd.Topological insulators with novel surfaces or edge states are the topological nature sequel of bulk electronic wave functions of these materials. The observed signatures in the electronic structure of topological insulators can make them excellent candidates for thermoelectric materials. Low dimensional materials such as phosphorene and Bi2Te3 nanowire have been confirmed to be desirable for the design of devices with high thermoelectric performance. So in this work, the phonon modes, formation energy and cohesive energy of LaX (X  =  Sb, Bi) monolayers are first calculated and investigated. Then the band order of these monolayers is investigated by the band structure calculations and the topological phase of these monolayers is proved by using the calculation of Z 2 topological invariant. The energy band gap and the band inversion strength of these monolayers are evaluated under in-plane strains. Also, the effect of different temperatures and in-plane strains on the thermoelectric performance of LaX monolayers is studied.