4,674 research outputs found
Insights of biosurfactant producing Serratia marcescens strain W2.3 isolated from diseased tilapia fish: a draft genome analysis
Background
Serratia marcescens is an opportunistic bacterial pathogen with broad range of host ranging from vertebrates, invertebrates and plants. S. marcescens strain W2.3 was isolated from a diseased tilapia fish and it was suspected to be the causal agent for the fish disease as virulence genes were found within its genome. In this study, for the first time, the genome sequences of S. marcescens strain W2.3 were sequenced using the Illumina MiSeq platform.
Result
Several virulent factors of S. marcescens such as serrawettin, a biosurfactant, has been reported to be regulated by N-acyl homoserine lactone (AHL)-based quorum sensing (QS). In our previous studies, an unusual AHL with long acyl side chain was detected from this isolate suggesting the possibility of novel virulence factors regulation. This evokes our interest in the genome of this bacterial strain and hereby we present the draft genome of S. marcescens W2.3, which carries the serrawettin production gene, swrA and the AHL-based QS transcriptional regulator gene, luxR which is an orphan luxR.
Conclusion
With the availability of the whole genome sequences of S. marcescens W2.3, this will pave the way for the study of the QS-mediated genes expression in this bacterium
Cost and Benefit Analysis of Line Arresters for a 69kV Transmission System in Taiwan
This paper presents a systematical evaluation experience on the performance and economic studies of line arresters for a 69 kV transmission system in Taiwan. The transient over-voltage phenomenon in high voltage transmission lines under lightning by using the Electro-Magnetic Transients Program (EMTP) package is well modeled and analyzed. The modeling for the simulated system including lightning, transmission line, transmission tower and line arrester are all considered to have more practical results. The cost and benefit evaluation for line arresters installation is then conducted to provide a reasonable suggestion for lightning protection. The performance of line arresters is evaluated by considering different installation schemes and lightning currents. Finally, a Taiwan’s experience is illustrated from both of the cost and benefit points of view
Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin
OBJECTIVE: The aim of this study was to evaluate the effect of multiple layers of an infection control barrier on the micro-hardness of a composite resin. MATERIAL AND METHODS: One, two, four, and eight layers of an infection control barrier were used to cover the light guides of a high-power light emitting diode (LeD) light curing unit (LCU) and a low-power halogen LCU. The composite specimens were photopolymerized with the LCUs and the barriers, and the micro-hardness of the upper and lower surfaces was measured (n=10). The hardness ratio was calculated by dividing the bottom surface hardness of the experimental groups by the irradiated surface hardness of the control groups. The data was analyzed by two-way ANOVA and Tukey's HSD test. RESULTS: The micro-hardness of the composite specimens photopolymerized with the LED LCU decreased significantly in the four- and eight-layer groups of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. The hardness ratio of the composite specimens wa
Learning Object-Centric Neural Scattering Functions for Free-viewpoint Relighting and Scene Composition
Photorealistic object appearance modeling from 2D images is a constant topic
in vision and graphics. While neural implicit methods (such as Neural Radiance
Fields) have shown high-fidelity view synthesis results, they cannot relight
the captured objects. More recent neural inverse rendering approaches have
enabled object relighting, but they represent surface properties as simple
BRDFs, and therefore cannot handle translucent objects. We propose
Object-Centric Neural Scattering Functions (OSFs) for learning to reconstruct
object appearance from only images. OSFs not only support free-viewpoint object
relighting, but also can model both opaque and translucent objects. While
accurately modeling subsurface light transport for translucent objects can be
highly complex and even intractable for neural methods, OSFs learn to
approximate the radiance transfer from a distant light to an outgoing direction
at any spatial location. This approximation avoids explicitly modeling complex
subsurface scattering, making learning a neural implicit model tractable.
Experiments on real and synthetic data show that OSFs accurately reconstruct
appearances for both opaque and translucent objects, allowing faithful
free-viewpoint relighting as well as scene composition. Project website:
https://kovenyu.com/osf/Comment: Project website: https://kovenyu.com/osf/ Journal extension of
arXiv:2012.08503. The first two authors contributed equally to this wor
Self-Isolated Dual-Mode High-Pass Birdcage RF Coil for Proton and Sodium MR Imaging at 7 T MRI
This study presents the feasibility of a dual-mode high-pass birdcage RF coil to acquire MR images at both 1H and 23Na frequencies at ultra-high-field MR scanner, 7 T. A dual-mode circuit (DMC) in the dual-mode birdcage (DMBC) RF coil operates at two frequencies, addressing the limitations of sensitivity reduction and isolation between two frequencies as in traditional dual-tuned RF coil. Finite-difference time-domain (FDTD) based electromagnetic (EM) simulations were performed to verify the RF coil at each frequency on the three-dimensional human head model. The DMBC RF coil resonated at proton (1H) and sodium (23Na) frequencies, and also single-tuned high-pass birdcage RF coils were constructed for both 1H and 23Na frequencies. The bench test performance of the RF coils was evaluated using network analysis parameters, including the measurement of scattering parameters (S-parameters) and quality factors (Q-factors). Q-factor of the DMBC coil at 1H port was 10.2% lower than that of 1H single-tuned birdcage (STBC) coil, with a modest SNR reduction of 6.5%. Similarly, the Q-factor for the DMBC coil at 23Na port was 12.3% less than that of 23Na STBC coil, and the SNR showed a minimal reduction of 5.4%. Utilizing the DMBC coil, promising 1H and 23Na MR images were acquired compared to those by using STBC coils. In conclusion, deploying a DMBC 1H/23Na coil has been demonstrated to overcome traditional constraints associated with dual-tuned RF coils, achieving this with only nominal signal attenuation across both nuclei operational frequencies
In-situ strain tuning of the Dirac surface states in Bi2Se3 films
Elastic strain has the potential for a controlled manipulation of the band
gap and spin-polarized Dirac states of topological materials, which can lead to
pseudo-magnetic-field effects, helical flat bands and topological phase
transitions. However, practical realization of these exotic phenomena is
challenging and yet to be achieved. Here, we show that the Dirac surface states
of the topological insulator Bi2Se3 can be reversibly tuned by an externally
applied elastic strain. Performing in-situ x-ray diffraction and in-situ
angle-resolved photoemission spectroscopy measurements during tensile testing
of epitaxial Bi2Se3 films bonded onto a flexible substrate, we demonstrate
elastic strains of up to 2.1% and quantify the resulting reversible changes in
the topological surface state. Our study establishes the functional
relationship between the lattice and electronic structures of Bi2Se3 and, more
generally, demonstrates a new route toward momentum-resolved mapping of
strain-induced band structure changes
Viewpoint switching in multiview videos using SP-frames
The distinguishing feature of multiview video lies in the interactivity, which allows users to select their favourite viewpoint. It switches bitstream at a particular view when necessary instead of transmitting all the views. The new SP-frame in H.264 is originally developed for multiple bit-rate streaming with the support of seamless switching. The SP-frame can also be directly employed in the viewpoint switching of multiview videos. Notwithstanding the guarantee of seamless switching using SP-frames, the cost is the bulky size of secondary SP-frames. This induces a significant amount of additional space or bandwidth for storage or transmission, especially for the multiview scenario. For this reason, a new motion estimation and compensation technique operating in the quantized transform (QDCT) domain is designed for coding secondary SP-frame in this paper. Our proposed work aims at keeping the secondary SP-frames as small as possible without affecting the size of primary SP-frames by incorporating QDCT-domain motion estimation and compensation in the secondary SP-frame coding. Simulation results show that the size of secondary SP-frames can be reduced remarkably in viewpoint switching. Index Terms — Multiview, viewpoint switching, SP-frame, QDCT-domain, motion estimatio
- …