Screening of specific diagnostic peptides of swine hepatitis E virus

© 2009 Zhao et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Complete sequences of KPC-2-encoding plasmid p628-KPC and CTX-M-55-encoding p628-CTXM coexisted in Klebsiella pneumoniae

A carbapenem-resistant Klebsiella pneumoniae strain 628 was isolated from a human case of intracranial infection in a Chinese teaching hospital. Strain 628 produces KPC-2 and CTX-M-55 encoded by two different conjugative plasmids, i.e., the IncFIIK plasmid p628-KPC and the IncI1 plasmid p628-CTXM, respectively. blaKPC-2 is captured by a Tn1721-based unit transposon with a linear structure ΔTn3-ISKpn27-blaKPC-2-ΔISKpn6-ΔTn1721, and this transposon together with a mercury resistance (mer) gene locus constitutes a 34 kb acquired drug-resistance region. blaKPC-2 has two transcription starts (nucleotides G and C located at 39 and 250 bp upstream of its coding region, respectively), which correspond to two promoters, i.e., the intrinsic P1 and the upstream ISKpn27/Tn3-provided P2 with the core -35/-10 elements TAATCC/TTACAT and TTGACA/AATAAT, respectively. blaCTX-M-55 is mobilized in an ISEcp1-blaCTX-M-55-Δorf477 transposition unit and appears to be the sole drug-resistant determinant in p628-CTXM. blaCTX-M-55 possesses a single transcription start (nucleotides G located at 116 bp upstream of its coding region), corresponding to the ISEcp1-provided P1 promoter with the core -35/-10 element TTGAAA/TACAAT. All the above detected promoters display a characteristic of constitutive expression. Coexistence of blaKPC and blaCTX-M in K. pneumoniae has been reported many times, but this is the first report to gain deep insights into genetic platforms, promoters, and expression of the two coexisted bla genes with determination of entire nucleotide sequences of the two corresponding plasmids

Specific, simple and rapid detection of porcine circovirus type 2 using the loop-mediated isothermal amplification method

<p>Abstract</p> <p>Background</p> <p>Porcine circovirus type 2 (PCV2) is the causative agent of postweaning multisystemic wasting syndrome (PMWS), and porcine dermatitis and nephropathy syndrome (PDNS). It has caused heavy losses in global agriculture in recent decades. Rapid detection of PCV2 is very important for the effective prophylaxis and treatment of PMWS.</p> <p>Results</p> <p>A loop-mediated isothermal amplification (LAMP) assay was used to detect PCV2 in this study. Three pairs of primers were specially designed for recognizing eight distinct sequences of the ORF2 gene. This gene lies in the PCV2 virus genome sequence, and encodes the Rep protein that is involved in virus replication. Time and temperature conditions for amplification of PCV2 genes were optimized to be 55 min at 59°C. The analysis of clinical samples indicated that the LAMP method was highly sensitive. The detection limit for PCV2 by the LAMP assay was 10 copies, whereas the limit by conventional PCR was 1000 copies. The assay did not cross-react with PCV1, porcine reproductive and respiratory syndrome virus, porcine epidemic diarrhea virus, transmissible gastroenteritis of pigs virus or rotavirus. When 110 samples were tested using the established LAMP system, 95 were detected as positive.</p> <p>Conclusion</p> <p>The newly developed LAMP detection method for PCV2 was more specific, sensitive, rapid and simple than before. It complements and extends previous methods for PCV2 detection and provides an alternative approach for detection of PCV2.</p

IDF: an Inconsistency Detection Framework – Performance Modeling and Guide to Its Design

With the increased popularity of replica-based services in distributed systems such as the Grid, consistency control among replicas becomes more and more important. To this end, IDF (Inconsistency Detection Framework), a two-layered overlay-based architecture, has been proposed as a new way to solve this problem—instead of enforcing a predefined protocol, IDF detects inconsistency in a timely manner when it occurs and resolves it based on applications’ semantics. This paper presents a comprehensive analytical study of IDF to assess its performance and provide insight into its design. More specifically, it develops an analytical model to characterize IDF. Based on this model, we evaluate the successful rate of inconsistency detection within the top layer, which directly impacts the performance of IDF. In addition, this model helps derive a unified formula to characterize a wide range of applications, providing practitioners and protocol designers with quantitative insights into the IDF design that can be potentially optimized to specific applications

Kinematic Simulation and Analysis of Globoidal Indexing Cam

As an important mechanism with intermittent motion, the globoidal indexing cam is always a research hot in the mechanical fields. The working profile of globoidal indexing cam is extremely complicated and undevelopable, which make it quite difficult to be protracted by the conventional drafting method. Aiming at this problem, the working curvilinear equation of the intermittent motion of an indexing cam is derived based on the RPY (Roll-Pitch-Yaw) coordinate transformation method. The 3D model based on the curvilinear equation is built by the Creo2.0 modeling software. The virtual prototype is established based on the ADAMS software, while the kinematics simulation is implemented. The success of virtual simulation verifies the correctness of curvilinear equation. The numerical results, presented and discussed in the paper, indicate that the proposed model is feasible to foresee the kinematic behaviour of an actual system

Airborne Downward Looking Sparse Linear Array 3-D SAR Heterogeneous Parallel Simulation

The airborne downward looking sparse linear array three dimensional synthetic aperture radar (DLSLA 3-D SAR) operates nadir observation with the along-track synthetic aperture formulated by platform movement and the cross-track synthetic aperture formulated by physical sparse linear array. Considering the lack of DLSLA 3-D SAR data in the current preliminary study stage, it is very important and essential to develop DLSLA 3-D SAR simulation (echo generation simulation and image reconstruction simulation, including point targets simulation and 3-D distributed scene simulation). In this paper, DLSLA 3-D SAR imaging geometry, the echo signal model and the heterogeneous parallel technique are discussed first. Then, heterogeneous parallel echo generation simulation with time domain correlation and the frequency domain correlation method is described. In the following, heterogeneous parallel image reconstruction simulation with two imaging algorithms, e.g., 3-D polar format algorithm, polar formatting and L1 regularization algorithm is discussed. Finally, the point targets and the 3-D distributed scene simulation are demonstrated to validate the effectiveness and performance of our proposed heterogeneous parallel simulation technique. The 3-D distributed scene employs airborne X-band DEM and P-band Circular SAR image of the same area as simulation scene input

Autonomous Navigation Airborne Forward-Looking SAR High Precision Imaging with Combination of Pseudo-Polar Formatting and Overlapped Sub-Aperture Algorithm

Autonomous navigation airborne forward-looking synthetic aperture radar (SAR) observes the anterior inferior wide area with a short cross-track dimensional linear array as azimuth aperture. This is an application scenario that is drastically different from that of side-looking space-borne or air-borne SAR systems, which acquires azimuth synthetic aperture with along-track dimension platform movement. High precision imaging with a combination of pseudo-polar formatting and overlapped sub-aperture algorithm for autonomous navigation airborne forward-looking SAR imaging is presented. With the suggested imaging method, range dimensional imaging is operated with wide band signal compression. Then, 2D pseudo-polar formatting is operated. In the following, azimuth synthetic aperture is divided into several overlapped sub-apertures. Intra sub-aperture IFFT (Inverse Fast Fourier Transform), wave front curvature phase error compensation, and inter sub-aperture IFFT are operated sequentially to finish azimuth high precision imaging. The main advantage of the proposed algorithm is its extremely high precision and low memory cost. The effectiveness and performance of the proposed algorithm are demonstrated with outdoor GBSAR (Ground Based Synthetic Aperture Radar) experiments, which possesses the same imaging geometry as the airborne forward-looking SAR (short azimuth aperture, wide azimuth swath). The profile response of the trihedral angle reflectors, placed in the imaging scene, reconstructed with the proposed imaging algorithm and back projection algorithm are compared and analyzed

Kinematic Simulation and Analysis of Globoidal Indexing Cam

As an important mechanism with intermittent motion, the globoidal indexing cam is always a research hot in the mechanical fields. The working profile of globoidal indexing cam is extremely complicated and undevelopable, which make it quite difficult to be protracted by the conventional drafting method. Aiming at this problem, the working curvilinear equation of the intermittent motion of an indexing cam is derived based on the RPY (Roll-Pitch-Yaw) coordinate transformation method. The 3D model based on the curvilinear equation is built by the Creo2.0 modeling software. The virtual prototype is established based on the ADAMS software, while the kinematics simulation is implemented. The success of virtual simulation verifies the correctness of curvilinear equation. The numerical results, presented and discussed in the paper, indicate that the proposed model is feasible to foresee the kinematic behaviour of an actual system