Detection of a closteroviruslike particle from a corky bark-affected grapevine cultivar

Closteroviruslike particles were mechanically transmitted from in vitro shoot tip cultures of a grapevine affected with corky bark disease to seedlings of Nicotiana benthamiana. Local necrotic lesions appeared 9-12 d and systemic symptoms 14-16 d post-inoculation. This virus had a normal length of 725 nm, striations with a pitch of 3.4 nm and was 10 nm wide. In ISEM tests, the virus was not decorated with antibodies prepared against GVA, NY-1, CA-4, GLRV-1, GLRV-3, ASGV, PVT or CLSV

Detection of capillovirus-like particles in a grapevine affected with rugose wood

Research Not

Mechanical sap transmission of a closterovirus from in vitro shoot tip cultures of a leafroll-affected grapevine to Nicotiana benthamiana

Transmission manuelle d'un clostérovirus au Nicotiana benthamiana à partir de cultures in vitro d'une vigne atteinte de l'enroulementDes cultures in vitro d'une vigne de Vitis vinifera Limberger atteinte de l'enroulement ont été broyées dans une solution tampon contenant de la nicotine. Les extraits ont été inoculés sur des feuilles de Nicotiana benthamiana et de 6 autres espèces de plantes herbacées. 3 semaines plus tard, seuls les plants de N. benthamiana ont démontré des symptômes. Ceux-ci consistaient d'un nanissement systémique accompagné d'un éclaircissement des nervures qui se transformait en chlorose interveinale. Les feuilles de ces N. benthamiana contenaient le virus A de la vigne (GVA), démontré par la méthode ISEM

Double-stranded RNA from rupestris stem pitting-affected grapevines

Nucleic acids were extracted from in vitro shoot tip cultures of 31 grapevine cultivars affected with rupestris stem pitting (RSP) disease and from cultures of 11 RSPfree cultivars, 4 of which were disease-free, 2 of which were fleck-affected and 5 of which were grapevine leafroll disease-affected. Analysis of the extracts by polyacrylamide slab gel electrophoresis showed that 21 of the 31 RSP-affected cultivars contained a previously unreported nucleic acid which was absent from the RSP-free controls. Nuclease digestions showed that the nucleic acid was double-stranded RNA (dsRNA). The apparent size of the dsRNA was inconsistent with that expected for either a viroid or a closterovirus. The observation that 10 of the 31 RSP-affected cultivars lacked this dsRNA is consistent with the view that there may be more than one 'RSP-like' disease. The dsRNA detected in this investigation may be associated with one of these diseases

Comparison of RNA extracts from in vitro shoot tip cultures of leafroll-affected and leafroll-free grapevine cultivars

The RNA content of in vitro shoot tip cultures from grapevine leafroll (GLR) disease-affected grapevines was analyzed and compared to that of similar cultures from GLR-free grapevines. A previously unreported low-molecular-weight single-stranded RNA (LMWssRNA) was detected in in vitro shoot tip cultures of 65 % (11 out of 17) of GLR-affected cultivars. This LMWssRNA was absent from disease-free cultivars and may be associated with a virus or a strain of a virus responsible for GLR. Numerous high-molecular-weight (HMW) dsRNA bands were also detected in GLR-affected grapevine cultivars. The intensities and mobilities (apparent molecular weights) of these dsRNA bands varied considerably from one GLR-affected cultivar to the next, but were reproducible for each cultivar. The detection of multiple distinctive RNA banding patterns is consistent with the possibility that more than one agent can cause grapevine leafroll disease

Grapevine virus C and grapevine leaf roll associated virus 2 are serologically related and appear to be the same virus

Protein extracted from grapevines infected with GLRaV-2 virus was subjected to electrophoresis, followed by Western blots. A protein band of about 23 kDa was detected in all infected plants. When GVC antibodies were used on blots obtained from the same infected plants, a similar protein band was detected in all infected plants. To address the possibility of the presence of another virus with the same molecular weight, the gene coding for the coat protein of GLRaV-2 was cloned and expressed in E. coli. The expressed protein reacted positively to both GLRaV- 2 and GVC antibodies. Using Immunosorbent Electron Microscopy (ISEM), polyclonal antibodies prepared against either GVC or GLRaV-2 trapped and decorated GLRaV-2 particles. The cDNA from GVC-infected grapevines and Nicotiana benthamiana were cloned and sequenced. All of the clones that were sequenced had the same sequence as GLRaV-2. Based on the data obtained, we concluded that GVC is the same virus as GLRaV-2. Keywords

Modal analysis of a spinning disk in a dense fluid as a model for high head hydraulic turbines

In high head Francis turbines and pump-turbines in particular, Rotor Stator Interaction (RSI) is an unavoidable source of excitation that needs to be predicted accurately. Precise knowledge of turbine dynamic characteristics, notably the variation of the rotor natural frequencies with rotation speed and added mass of the surrounding water, is essential to assess potential resonance and resulting amplification of vibrations. In these machines, the disk-like structures of the runner crown and band as well as the head cover and bottom ring give rise to the emergence of diametrical modes and a mode split phenomenon for which no efficient prediction method exists to date. Fully coupled Fluid-Structure Interaction (FSI) methods are too computationally expensive; hence, we seek a simplified modelling tool for the design and the expected-life prediction of these turbines. We present the development of both an analytical modal analysis based on the assumed mode approach and potential flow theory, and a modal force Computational Fluid Dynamics (CFD) approach for rotating disks in dense fluid. Both methods accurately predict the natural frequency split as well as the natural frequency drift within 7.9% of the values measured experimentally. The analytical model explains how mode split and drift are respectively caused by linear and quadratic dependence of the added mass with relative circumferential velocity between flexural waves and fluid rotation

ENABLING WARFARE AT THE SPEED OF LIGHT: A COMPARATIVE ANALYSIS OF MULTI-MISSION HIGH ENERGY LASER RADARS

This capstone report provides a cost effectiveness analysis of various radar systems capable of guiding the Multi-Mission High Energy Laser (MMHEL) from a Stryker platform. The Army's Rapid Capability and Critical Technologies Office (RCCTO) is developing the MMHEL to provide a Mobile Short-Range Air Defense (MSHORAD) capability to maneuver units. The MMHEL requires a radar to cue the fire control system for target engagement. Past efforts to employ high-energy lasers have relied on large, stationary radars for target acquisition. The reliance on such radars limits a unit's ability to maneuver and results in the laser being employed primarily from a defensive posture. To maximize maneuverability and enable the offensive employment of the MMHEL, the U.S. Army needs an on-platform radar that is compact and inexpensive enough to equip multiple Strykers within a Stryker Brigade Combat Team with the capability to engage targets from a mobile platform. The RCCTO is currently tasked with accelerating efforts to fill this need. The intent of this report is to assist the RCCTO in these efforts by generating a list of viable radar alternatives and conducting a cost effectiveness analysis to produce a recommendation of the most optimal solution. The results indicate that RADA's aCHR radar presents the best value in terms of cost and benefit to the warfighter.http://archive.org/details/enablingwarfarea1094564109Captain, United States ArmyCaptain, United States ArmyMajor, United States ArmyCaptain, United States ArmyCaptain, United States ArmyApproved for public release; distribution is unlimited

Critical behavior of a fluid in a disordered porous matrix: An Ornstein-Zernike approach

Using a liquid-state approach based on Ornstein-Zernike equations, we study the behavior of a fluid inside a porous disordered matrix near the liquid-gas critical point.The results obtained within various standard approximation schemes such as lowest-order $\gamma$-ordering and the mean-spherical approximation suggest that the critical behavior is closely related to that of the random-field Ising model (RFIM).Comment: 10 pages, revtex, to appear in Physical Review Letter

Avalanches in Breakdown and Fracture Processes

We investigate the breakdown of disordered networks under the action of an increasing external---mechanical or electrical---force. We perform a mean-field analysis and estimate scaling exponents for the approach to the instability. By simulating two-dimensional models of electric breakdown and fracture we observe that the breakdown is preceded by avalanche events. The avalanches can be described by scaling laws, and the estimated values of the exponents are consistent with those found in mean-field theory. The breakdown point is characterized by a discontinuity in the macroscopic properties of the material, such as conductivity or elasticity, indicative of a first order transition. The scaling laws suggest an analogy with the behavior expected in spinodal nucleation.Comment: 15 pages, 12 figures, submitted to Phys. Rev. E, corrected typo in authors name, no changes to the pape