840 research outputs found
Evolution and Diversity of the Human Hepatitis D Virus Genome
Human hepatitis delta virus (HDV) is the smallest RNA virus in genome. HDV genome is divided into a viroid-like sequence and a protein-coding sequence which could have originated from different resources and the HDV genome was eventually constituted through RNA recombination. The genome subsequently diversified through accumulation of mutations selected by interactions between the mutated RNA and proteins with host factors to successfully form the infectious virions. Therefore, we propose that the conservation of HDV nucleotide sequence is highly related with its functionality. Genome analysis of known HDV isolates shows that the C-terminal coding sequences of large delta antigen (LDAg) are the highest diversity than other regions of protein-coding sequences but they still retain biological functionality to interact with the heavy chain of clathrin can be selected and maintained. Since viruses interact with many host factors, including escaping the host immune response, how to design a program to predict RNA genome evolution is a great challenging work
The Nucleolus of Caenorhabditis elegans
Nucleolar size and appearance correlate with ribosome biogenesis and cellular activity. The mechanisms underlying changes in nucleolar appearance and regulation of nucleolar size that occur during differentiation and cell cycle progression are not well understood. Caenorhabditis elegans provides a good model for studying these processes because of its small size and transparent body, well-characterized cell types and lineages, and because its cells display various sizes of nucleoli. This paper details the advantages of using C. elegans to investigate features of the nucleolus during the organism's development by following dynamic changes in fibrillarin (FIB-1) in the cells of early embryos and aged worms. This paper also illustrates the involvement of the ncl-1 gene and other possible candidate genes in nucleolar-size control. Lastly, we summarize the ribosomal proteins involved in life span and innate immunity, and those homologous genes that correspond to human disorders of ribosomopathy
A balanced homodyne detector for high-rate Gaussian-modulated coherent-state quantum key distribution
We discuss excess noise contributions of a practical balanced homodyne
detector in Gaussian-modulated coherent-state (GMCS) quantum key distribution
(QKD). We point out the key generated from the original realistic model of GMCS
QKD may not be secure. In our refined realistic model, we take into account
excess noise due to the finite bandwidth of the homodyne detector and the
fluctuation of the local oscillator. A high speed balanced homodyne detector
suitable for GMCS QKD in the telecommunication wavelength region is built and
experimentally tested. The 3dB bandwidth of the balanced homodyne detector is
found to be 104MHz and its electronic noise level is 13dB below the shot noise
at a local oscillator level of 8.5*10^8 photon per pulse. The secure key rate
of a GMCS QKD experiment with this homodyne detector is expected to reach
Mbits/s over a few kilometers.Comment: 22 pages, 11 figure
The C-terminal sequence of the large hepatitis delta antigen is variable but retains the ability to bind clathrin
A Novel Surgical Technique: Single-Incision Transumbilical Laparoscopic Roux-en-Y Gastric Bypass
Conventional laparoscopic Roux-en-Y gastric bypass (LRYGB) is a gold standard for bariatric surgery, but the procedure requires five to seven incisions for placement of multiple trocars and thus may produce less-than-ideal cosmetic results. We have developed a new approach, single-incision transumbilical LRYGB (SITU-LRYGB) to treat morbid obesity. We compared the surgical results and patient satisfaction in a study of five-port LRYGB and SITU-LRYGB. Fifty morbidly obese patients (14 males, 36 females) underwent either Roux-en-Y gastric bypass with five-port LRYGB or the SITU-LRYGB approach. During the operation, we used a novel intraoperative liver traction method with a “liver suspension tape” that we specifically designed for SITU-LRYGB. Compared to five-port surgery with SITU-LRYGB, there were no intraoperative complications, wound healing was excellent, and there was no abdominal scarring. SITU surgical time was longer than that with five-port LRYGB (99.8 vs. 67.6 min, P < 0.001). Patients treated with the five-port method were more obese than those in the SITU group (127.9 vs. 112.4 kg, P = 0.016). After the bariatric surgery, no difference in comorbidity was found in both groups. Patient satisfaction was greater with SITU than with the five-port method (4.48 vs. 3.96, P = 0.006). Roux-en-Y gastric bypass can be successfully achieved via a single umbilical incision, a method that provides a short operative time and good recovery and eliminates abdominal scarring
Extensive Reading with Guidance
A language learning mode called “word-focused extensive reading” has been proposed to facilitate word-usage learning. The user inputs a word in the computer program designed and implemented for reading to find its usage in the context of a sentence. The computer program then searches for the knowledge base for the word and provides guidance to show a summary of the salient features of word collocation. Sentences with the word in question are displayed one at a time. For each sentence the relevant collocating words are highlighted. In this way the reader sees the word collocation so as to recognize the salient features of the word and thus incrementally acquires the knowledge of word usage. The program works with large Chinese and English collections of texts. For Chinese the knowledge of word collocation was built on the basis of the Balanced Corpus of Academia Sinica. The English collocation features were collected from the British National Corpus. The program can also be useful for learning to differentiate near-synonyms
The 3D-tomography of the nano-clusters formed by Fe-coating and annealing of diamond films for enhancing their surface electron field emitters
[[abstract]]The Fe-coating and H2-annealed processes markedly increased the conductivity and enhanced the surface electron field emission (s-EFE) properties for the diamondfilms. The enhancement on the s-EFE properties for the diamondfilms is presumably owing to the formation of nano-graphite clusters on the surface of the films via the Fe-to-diamond interaction. However, the extent of enhancement varied with the granular structure of the diamondfilms. For the microcrystalline (MCD)films, the s-EFE process can be turned on at (E0)MCD = 1.9 V/μm, achieving a large s-EFE current density of (Je)MCD = 315 μA/cm2 at an applied field of 8.8 V/μm. These s-EFE properties are markedly better than those for Fe-coated/annealed ultrananocrystalline diamond(UNCD)films with (E0)UNCD = 2.0 V/μm and (Je)UNCD = 120 μA/cm2. The transmission electron microscopy showed that the nano-graphite clusters formed an interconnected network for MCDfilms that facilitated the electron transport more markedly, as compared with the isolated nano-graphitic clusters formed at the surface of the UNCDfilms. Therefore, the Fe-coating/annealing processes improved the s-EFE properties for the MCDfilms more markedly than that for the UNCDfilms. The understanding on the distribution of the nano-clusters is of critical importance in elucidating the authentic factor that influences the s-EFE properties of the diamondfilms. Such an understanding is possible only through the 3D-tomographic investigations.[[journaltype]]國外[[ispeerreviewed]]Y[[booktype]]電子版[[countrycodes]]US
Mitigating Routing Misbehavior Using Ant-Tabu-Based Routing Algorithm for Wireless Ad-Hoc
Summary Routing is a key factor in the design of modern communication networks, especially in wireless ad-hoc networks (WANs). In WANs, both selfish and malicious nodes are misbehaving nodes and cause severely routing and security problems. Selfish nodes may drop routing and data packets and malicious nodes may redirect the packets to another routing path or launch denial-of-service (DoS) attacks. In this paper, an efficient routing algorithm is proposed, Ant-Tabu-Based Routing Algorithm (ATBRA), to mitigate selfish problem and reduce routing overheads. In ATBRA, both the concepts of ant-based routing algorithm and Tabu search are applied. We compare the performance of the proposed scheme with that of DSR in terms of two performance metrics: successful delivery rate (SDR) and routing overhead (RO). By comparisons, we notice that the proposed algorithm outperforms DSR in all two categories. The simulation results also indicate that the proposed algorithm is more efficient than DSR
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