Electron heat flux and propagating fronts in plasma thermal quench via ambipolar transport

The thermal collapse of a nearly collisionless plasma interacting with a cooling spot, in which the electron parallel heat flux plays an essential role, is investigated both theoretically and numerically. We show that such thermal collapse, which is known as thermal quench in tokamaks, comes about in the form of propagating fronts, originating from the cooling spot, along the magnetic field lines. The slow fronts, propagating with local ion sound speed, limit the aggressive cooling of plasma, which is accompanied by a plasma cooling flow toward the cooling spot. The extraordinary physics underlying such a cooling flow is that the fundamental constraint of ambipolar transport along the field line limits the spatial gradient of electron thermal conduction flux to the much weaker convective scaling, as opposed to the free-streaming scaling, so that a large electron temperature and hence pressure gradient can be sustained. The last ion front for a radiative cooling spot is a shock front where cold but flowing ions meet the hot ions

Optomechatronics in retroreflective grating metrology for 3D surface measurement.

With an explosion of technology occurring, optomechatronics is proposed as a general engineering area for the coming century. Optomechatronics is the integration of optical, mechanical, electrical, and other traditional engineering disciplines with microelectronics in order to unify machine and information technology. An optomechatronic product is a machine with knowledge and intelligence, which can process information and take action in response to human needs, other machines and the environment. Future trends in optomechatronic products will see smaller, swifter, and smarter systems. Optomechatronics provides a vision for engineers to meet the challenge of intellectural broadness in technology. Retroreflective gratin metrology is viewed as an example to illustrate optomechatronics. Retroreflective grating metrology is a new optical technique for measuring the derivative and contour of quasi flat and reflective surfaces. It is based on a retroreflective process in which the retroreflective screw is very efficient in returning light to the light source. Uniform gratings can be produced in the optical process by attachment painting, projection, moire methods, etc. The gratings are modulated in phase by the surface under test. A efficient-and simple mathematical model can relate the phase information in the deformed gratings to the derivative of the surface at each point A variety of DFT (Discrete Fourier Transform) and PST (Phase shifting Technology) algorithms can be used to extract the phase information in the deformed gratings. The contour of the surface is found by integration. Experiments show that the method can detect slope related defects smaller than 10 microns, very efficiently. The retroreflective grating metrology has been used to measure the 3D surface waviness on calibrated artifacts. In order to eliminate the effect of the illumination angle, a nonlinear equation was developed explicitly to calculate the slope from the phase information. The optical configuration for projection gratings technique was used for the measurement The three-step PST algorithm was applied to analyze the grating image Three calibrated artifacts with different wave amplitude were tested. The experiments show that the retroreflective metrology can recover the contour and amplitude of the 3D surface waviness on the standard artifacts successfully. Retroreflective grating metrology is one of the most precise among the existing optical methods. This represents a new optical technique for surface measurement, which is efficient, practical and cost-effective compared to other existing optical methods such as grids, Moire fringes, optical triangulation, and so on. This technology can be developed for machine vision and industrial application in Nondestructive Testing and Evaluation (NDTE).Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2000 .Z53. Source: Dissertation Abstracts International, Volume: 61-09, Section: B, page: 4951. Adviser: W. P. T. North. Thesis (Ph.D.)--University of Windsor (Canada), 2000

Intracerebral Administration of Recombinant Rabies Virus Expressing GM-CSF Prevents the Development of Rabies after Infection with Street Virus

Recently it was found that prior immunization with recombinant rabies virus (RABV) expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) (LBNSE-GM-CSF) resulted in high innate/adaptive immune responses and protection against challenge with virulent RABV (Wen et al., JVI, 2011). In this study, the ability of LBNSE-GM-CSF to prevent animals from developing rabies was investigated in mice after infection with lethal doses of street RABV. It was found that intracerebral administration of LBNSE-GM-CSF protected more mice from developing rabies than sham-treated mice as late as day 5 after infection with street RABV. Intracerebral administration of LBNSE-GM-CSF resulted in significantly higher levels of chemokine/cytokine expression and more infiltration of inflammatory and immune cells into the central nervous system (CNS) than sham-administration or administration with UV-inactivated LBNSE-GM-CSF. Enhancement of blood-brain barrier (BBB) permeability and increases in virus neutralizing antibodies (VNA) were also observed in mice treated with LBNSE-GM-CSF. On the other hand, intracerebral administration with UV-inactivated LBNSE-GM-CSF did not increase protection despite the fact that VNA were induced in the periphery. However, intracerebral administration with chemoattractant protein-1 (MCP-1, also termed CCL2) increased significantly the protective efficacy of UV-inactivated LBNSE-GM-CSF. Together these studies confirm that direct administration of LBNSE-GM-CSF can enhance the innate and adaptive immunity as well as the BBB permeability, thus allowing infiltration of inflammatory cells and other immune effectors enter into the CNS to clear the virus and prevent the development of rabies

Poly[bis­(2,2′-bipyridine-κ2 N,N′)deca-μ-oxido-dioxidodicopper(II)tetra­vanadium(V)]

The title compound, [Cu2V4O12(C10H8N2)2]n, shows a two-dimensional copper–vanadate layer composed of eight-membered rings, each containing four corner-sharing VO4 tetra­hedra; these are linked through six penta­coordinated CuII atoms with the 2,2′-bipyridine ligands attached and pointing above and below the plane of the layer. The Cu atom is coordinated by two N donors from the 2,2′-bipyridine ligand and three O atoms from three adjacent VO4 units to form a distorted tetragonal pyramid. These layers are further connected by π–π inter­actions between inter­leaving bipyridine ligands of adjacent layers [centroid–centroid distances = 3.63 (1) and 3.68 (1) Å] into a three-dimensional supra­molecular structure

Characterization of monoclonal antibodies that specifically differentiate field isolates from vaccine strains of classical swine fever virus

Classical swine fever virus (CSFV) is a major animal pathogen threatening the global pork industry. To date, numerous anti-CSFV monoclonal antibodies (mAbs) and their recognizing epitopes have been reported. However, few mAbs were systematically characterized for the capacity to differentiate field CSFV isolates from CSF vaccine strains, and the molecular basis associated with antigenic differences between vaccines and field isolates is still largely unknown. In the present study, recombinant CSFV structural glycoproteins E2 of both virulent and vaccine strains and Erns of vaccine strain were expressed using eukaryotic cells and murine mAbs generated against E2 and Erns. After serial screening and cloning of the hybridomas, the viral spectra of mAbs were respectively determined by indirect fluorescent antibody assay (IFA) using 108 CSFVs, followed by Western blot analysis using expressed glycoproteins of all CSFV sub-genotypes including vaccine strains. The antigenic structures recognized by these mAbs were characterized by epitope mapping using truncated, chimeric, and site-directed mutated E2 and Erns proteins. We have identified two vaccine-specific, one field isolate-specific, and two universal CSFV-specific mAbs and five novel conformational epitopes with critical amino acid (aa) motifs that are associated with these five mAbs: 213EPD215, 271RXGP274, and 37LXLNDG42 on E2 and 38CKGVP42, W81, and D100/V107 on Erns. Particularly, E213 of E2 is field isolate-specific, while N40 of E2 and D100/V107 of Erns are vaccine strain-specific. Results from our study further indicate that N40D of E2 mutation in field strains was likely produced under positive selection associated with long-term mass vaccination, leading to CSFV evasion of host immune response. Taking together, this study provides new insights into the antigenic structure of CSFV E2 and Erns and the differentiating mAbs will contribute to the development of a diagnostic strategy to differentiate C-strain vaccination from natural infection (DIVA) of CSFV in terms of elimination of CSF in China

Identification of Amino Acids in HA and PB2 Critical for the Transmission of H5N1 Avian Influenza Viruses in a Mammalian Host

Since 2003, H5N1 influenza viruses have caused over 400 known cases of human infection with a mortality rate greater than 60%. Most of these cases resulted from direct contact with virus-contaminated poultry or poultry products. Although only limited human-to-human transmission has been reported to date, it is feared that efficient human-to-human transmission of H5N1 viruses has the potential to cause a pandemic of disastrous proportions. The genetic basis for H5N1 viral transmission among humans is largely unknown. In this study, we used guinea pigs as a mammalian model to study the transmission of six different H5N1 avian influenza viruses. We found that two viruses, A/duck/Guangxi/35/2001 (DKGX/35) and A/bar-headed goose/Qinghai/3/2005(BHGQH/05), were transmitted from inoculated animals to naïve contact animals. Our mutagenesis analysis revealed that the amino acid asparagine (Asn) at position 701 in the PB2 protein was a prerequisite for DKGX/35 transmission in guinea pigs. In addition, an amino acid change in the hemagglutinin (HA) protein (Thr160Ala), resulting in the loss of glycosylation at 158–160, was responsible for HA binding to sialylated glycans and was critical for H5N1 virus transmission in guinea pigs. These amino acids changes in PB2 and HA could serve as important molecular markers for assessing the pandemic potential of H5N1 field isolates

A fully discrete finite element method for a constrained transport model of the incompressible MHD equations

In this paper, we propose and analyze a fully discrete finite element method for a constrained transport (CT) model of the incompressible magnetohydrodynamic (MHD) equations. The spatial discretization is based on mixed finite elements, where the hydrodynamic unknowns are approximated by stable finite element pairs, the magnetic field and magnetic vector potential are discretized by H(curl)-conforming edge element. The time marching is combining a backward Euler scheme and some subtle implicit-explicit treatments for nonlinear and coupling terms. With these treatments, the fully discrete scheme is linear in the implementation and the computation of the magnetic vector potential is decoupled from the whole coupled system. The most attractive feature of this scheme that it can yield the exactly divergence-free magnetic field and current density on the discrete level. The unique solvability and unconditional stability of the scheme are also proved rigorously. By utilizing the energy argument, error estimates for the velocity, magnetic field and magnetic vector potential are further demonstrated under the low regularity hypothesis for the exact solutions. Numerical results are provided to verify the theoretical analysis and to show the effectiveness of the proposed scheme

Particle-in-cell simulation study of a 0.42 THz second-harmonic gyrotron oscillator

In this paper, a gyrotron oscillator operating at 0.42 THz is studied by Particle-in-cell simulation. Under the condition of a beam voltage of 12 kV, beam current of 160 mA and magnetic field of 7.665 T, the gyrotron can operate stably in the TE06 mode at the second-harmonic. Its output power of continuous wave (CW) is up to 82 W corresponding to an efficiency rate of 4.1