98 research outputs found
Image reconstruction through a multimode fiber with a simple neural network architecture
Multimode fibers (MMFs) have the potential to carry complex images for
endoscopy and related applications, but decoding the complex speckle patterns
produced by mode-mixing and modal dispersion in MMFs is a serious challenge.
Several groups have recently shown that convolutional neural networks (CNNs)
can be trained to perform high-fidelity MMF image reconstruction. We find that
a considerably simpler neural network architecture, the single hidden layer
dense neural network, performs at least as well as previously-used CNNs in
terms of image reconstruction fidelity, and is superior in terms of training
time and computing resources required. The trained networks can accurately
reconstruct MMF images collected over a week after the cessation of the
training set, with the dense network performing as well as the CNN over the
entire period.Comment: 17 pages, 10 figure
Influence of surface properties on the electrical conductivity of silicon nanomembranes
Because of the large surface-to-volume ratio, the conductivity of semiconductor nanostructures is very sensitive to surface chemical and structural conditions. Two surface modifications, vacuum hydrogenation (VH) and hydrofluoric acid (HF) cleaning, of silicon nanomembranes (SiNMs) that nominally have the same effect, the hydrogen termination of the surface, are compared. The sheet resistance of the SiNMs, measured by the van der Pauw method, shows that HF etching produces at least an order of magnitude larger drop in sheet resistance than that caused by VH treatment, relative to the very high sheet resistance of samples terminated with native oxide. Re-oxidation rates after these treatments also differ. X-ray photoelectron spectroscopy measurements are consistent with the electrical-conductivity results. We pinpoint the likely cause of the differences
Three-dimensional electron ptychography of organic-inorganic hybrid nanostructures
Three dimensional scaffolded DNA origami with inorganic nanoparticles has been used to create tailored multidimensional nanostructures. However, the image contrast of DNA is poorer than those of the heavy nanoparticles in conventional transmission electron microscopy at high defocus so that the biological and non-biological components in 3D scaffolds cannot be simultaneously resolved using tomography of samples in a native state. We demonstrate the use of electron ptychography to recover high contrast phase information from all components in a DNA origami scaffold without staining. We further quantitatively evaluate the enhancement of contrast in comparison with conventional transmission electron microscopy. In addition, We show that for ptychography post-reconstruction focusing simplifies the workflow and reduces electron dose and beam damage
Comparative Genomics, Whole-Genome Re-sequencing and Expression Profile Analysis of Nucleobase:Cation Symporter 2 (NCS2) Genes in Maize
Nucleobase:cation symporter 2 (NCS2) proteins are important for the transport of free nucleobases, participating in diverse plant growth and developmental processes, as well as response to abiotic stress. To date, a comprehensive analysis of the NCS2 gene family has not been performed in maize. In this study, we conducted a comparative genomics analysis of NCS2 genes in 28 plant species, ranging from aquatic algae to land plants, concentrating mainly on maize. Gene duplication events contributed to the expansion of NCS2 genes from lower aquatic plants to higher angiosperms, and whole-genome/segmental and single-gene duplication events were responsible for the expansion of the maize NCS2 gene family. Phylogenetic construction showed three NCS2 subfamilies, I, II, and III. According to homology-based relationships, members of subfamily I are NCS2/AzgA-like genes, whereas those in subfamilies II and III are NCS2/NATs. Moreover, subfamily I exhibited ancient origins. A motif compositional analysis showed that one symbolic motif (motif 4) of the NCS2/NAT genes was absent in subfamily I. In maize, three NCS2/AzgA-like and 21 NCS2/NAT genes were identified, and purifying selection influenced the duplication of maize NCS2 genes. Additionally, a population genetic analysis of NCS2 genes revealed that ZmNCS2â21 showed the greatest diversity between the 78 inbred and 22 wild surveyed maize populations. An expression profile analysis using transcriptome data and quantitative real-time PCR revealed that NCS2 genes in maize are involved in diverse developmental processes and responses to abiotic stresses, including abscisic acid, salt (NaCl), polyethylene glycol, and low (4°C) and high (42°C) temperatures. ZmNCS2 genes with relatively close relationships had similar expression patterns, strongly indicating functional redundancy. Finally, ZmNCS2â16 and ZmNCS2â23 localize in the plasma membrane, which confirmed their predicted membrane structures. These results provide a foundation for future studies regarding the functions of ZmNCS2 proteins, particularly those with potentially important roles in plant responses to abiotic stresses
Three-dimensional electron ptychography of organicâinorganic hybrid nanostructures
Three dimensional scaffolded DNA origami with inorganic nanoparticles has been used to create tailored multidimensional nanostructures. However, the image contrast of DNA is poorer than those of the heavy nanoparticles in conventional transmission electron microscopy at high defocus so that the biological and non-biological components in 3D scaffolds cannot be simultaneously resolved using tomography of samples in a native state. We demonstrate the use of electron ptychography to recover high contrast phase information from all components in a DNA origami scaffold without staining. We further quantitatively evaluate the enhancement of contrast in comparison with conventional transmission electron microscopy. In addition, We show that for ptychography post-reconstruction focusing simplifies the workflow and reduces electron dose and beam damage
Determination of optimal parameters for dual-layer cathode of polymer electrolyte fuel cell using computational intelligence-aided design.
Because of the demands for sustainable and renewable energy, fuel cells have become increasingly popular, particularly the polymer electrolyte fuel cell (PEFC). Among the various components, the cathode plays a key role in the operation of a PEFC. In this study, a quantitative dual-layer cathode model was proposed for determining the optimal parameters that minimize the over-potential difference η and improve the efficiency using a newly developed bat swarm algorithm with a variable population embedded in the computational intelligence-aided design. The simulation results were in agreement with previously reported results, suggesting that the proposed technique has potential applications for automating and optimizing the design of PEFCs
Evolution of Tourism Risk Communication: A Bibliometric Analysis and Meta-Analysis of the Antecedents of Communicating Risk to Tourists
As tourism risk communication has transitioned from an emerging theme to a growing field of research, it is essential to review existing studies to identify developments in it. Nevertheless, there is a lack of extensive research employing both bibliometric and meta-analysis of tourism risk communication, specifically on communicating risk to tourists. To fill this gap, first, we applied bibliometric analysis techniques to identify emerging research clusters by collecting 236 articles from 1985.1.1 to 2023.6.1. Second, to implement the meta-analysis, we selected the empirical results from the collected articles. Then, five studies were used as a series of different structures required for implementing meta-analysis. Through our research, the main results show that (1) emerging research clusters mainly focus on: (i) ârisk communicationâ, âcrisis communicationâ, and âtourism crisisâ, (ii) ârisk perceptionâ, (iii) âhealth serviceâ, âhealth educationâ, âhealth behaviorâ, âenvironmental healthâ, and âpublic healthâ. (2) Papers aiming at data analysis or modeling are of great value to advance research in the field of tourism risk communication. (3) Tourism risk communication assessments reported by different public agencies are sensitive to factors such as gender, nationality, the experiences of tourists, local tourism boards, local governments, organizational resource allocation, and report evaluation. Based on this, we contribute to knowledge on tourism risk management by discussing the challenges of the present studies and, more significantly, by identifying seven antecedents and future research directions of risk communication strategy. Finally, this paper draws implications for theory development, acknowledges the limitations of this research, and indicates further research directions
A Review of the High-Power All-Solid-State Single-Frequency Continuous-Wave Laser
High-power all-solid-state single-frequency continuous-wave (CW) lasers have been applied in basic research such as atomic physics, precision measurement, radar and laser guidance, as well as defense and military fields owing to their intrinsic advantages of high beam quality, low noise, narrow linewidth, and high coherence. With the rapid developments of sciences and technologies, the traditional single-frequency lasers cannot meet the development needs of emerging science and technology such as quantum technology, quantum measurement and quantum optics. After long-term efforts and technical research, a novel theory and technology was proposed and developed for improving the whole performance of high-power all-solid-state single-frequency CW lasers, which was implemented by actively introducing a nonlinear optical loss and controlling the stimulated emission rate (SER) in the laser resonator. As a result, the output power, power and frequency stabilities, tuning range and intensity noise of the single-frequency lasers were effectively enhanced
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