Localized reconnection in the near jovian magnetotail     

CT Russell  KK Khurana  DE Huddleston  MG Kivelson 《Science (New York, N.Y.)》1998,280(5366):1061-1064

The oppositely directed magnetic field in the jovian magnetic tail is expected eventually to reconnect across the current sheet, allowing plasma produced deep inside the magnetosphere near Io's orbit to escape in the antisolar direction down the tail. The Galileo spacecraft found localized regions of strong northward and southward field components beyond about 50 jovian radii in the postmidnight, predawn sector of the jovian magnetosphere. These pockets of vertical magnetic fields can be stronger than the surrounding magnetotail and magnetodisk fields. They may result from episodic reconnection of patches of the near jovian magnetotail.  相似文献   

Structure‐activity relationship studies on naphthoquinone analogs. The search for new herbicides based on natural products     

Alexandra G Durn  Nuria Chinchilla  Jos MG Molinillo  Francisco A Macías 《Pest management science》2019,75(9):2517-2529

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Agricultural insect hybridization and implications for pest management     

Alberto S Corrêa  Erick MG Cordeiro  Celso Omoto 《Pest management science》2019,75(11):2857-2864

Biological invasions, the expansion of agricultural frontiers, and climate change favor encounters of divergent lineages of animals and plants, increasing the likelihood of hybridization. However, hybridization of insect species and its consequences for agroecosystems have not received sufficient attention. Gene exchange between distinct and distant genetic pools can improve the survival and reproduction of insect pests, and threaten beneficial insects in disturbed agricultural environments. Hybridization may be the underlying explanation for the recurrent pest outbreaks and control failures in putative hybrid zones, as suspected for bollworm, corn borer, whiteflies, and stink bugs. Reliable predictions of the types of changes that can be expected in pest insect genomes and fitness, and of their impacts on the fate of species and populations remain elusive. Typical steps in pest management, such as insect identification, pest monitoring, and control are likely affected by gene flow and adaptive introgression mediated by hybridization, and we do not have ways to respond to or mitigate the problem. To address the adverse effects of farming intensification and global trade, we must ensure that current integrated pest management programs incorporate up‐to‐date monitoring and diagnostic tools. The rapid identification of hybrids, quantification of levels of introgression, and in‐depth knowledge of what genes have been transferred may help to explain and predict insect population outbreaks and control failures in the future. © 2019 Society of Chemical Industry  相似文献   

A Magnetic Signature at Io: Initial Report from the Galileo Magnetometer   总被引：1，自引：0，他引：1  

MG Kivelson  KK Khurana  RJ Walker  CT Russell  JA Linker  DJ Southwood  C Polanskey 《Science (New York, N.Y.)》1996,273(5273):337-340

During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by Io. A field decrease, of nearly 40 percent of the background jovian field at closest approach to Io, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at Io would explain the observations. It seems plausible that Io, like Earth and Mercury, is a magnetized solid planet.  相似文献   

Hoof balance in equine lameness     

Gayle W. Trotter DVM  MS 《Journal of Equine Veterinary Science》2004,24(11):494-495

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Influence of cavity size, seedling growing density and fungicide applications on Keithia blight of western redcedar seedling growth and field performance     

H. H. Kope  J. Sutherland  D. Trotter 《New Forests》1996,11(2):137-147

To determine the influence of cavity size, seedling density and fungicide application on severity of Keithia blight caused by the fungus Didymascella thujina (Durand) Maire, western redcedar (Thuja plicata Donn) seedlings were grown in styroblocks of 3 cavity sizes, thinned to 3 growing densities and sprayed several times monthly with mancozeb fungicide. After two growing seasons cavity size, seedling growing density and number of fungicide applications all significantly (p0.05) affected blight severity. Blight severity was inversely related to the number of mancozeb fungicide applications. The only significant two-way interaction was for cavity size and seedling growing density.Eighteen seedlings from each of the nine cavity sizes and seedling densities combinations were assessed for shoot height, root collar diameter and blight severity, prior to planting at both Holt Creek and Salmon Creek on Vancouver Island, British Columbia in March 1994. Growth was reassessed during October 1994. Seedling height and root collar diameter increased significantly (p0.05) with certain cavity size and seedling density combinations. Blight severity increased significantly (p0.05) for all nine treatments at both sites, however, between sites blight severity increased significantly (p0.05) only at the wetter, Salmon Creek site.  相似文献   

Effects of polysulfated glycosaminoglycan on chemical and physical defects in equine articular cartilage   总被引：1，自引：0，他引：1  

J V Yovich  G W Trotter  C W McIlwraith  R W Norrdin 《American journal of veterinary research》1987,48(9):1407-1414

The effect of intra-articular polysulfated glycosaminoglycan (PSG) on repair of chemical and physical articular cartilage injuries was evaluated in 8 horses. In each horse, a partial- and a full-thickness articular cartilage defect was made on the distal articular surface of the radial carpal bone. In the contralateral middle carpal joint, a chemical articular cartilage injury was induced by injecting 50 mg of Na monoiodoacetate (MIA). Four of the 8 horses were not treated (controls), and 4 horses were treated by intra-articular injection of 250 mg of PSG into both middle carpal joints once a week for 5 treatments starting 1 week after cartilage injury. Horses were maintained for 8 weeks. There was less joint circumference enlargement in PSG-treated horses in MIA-injected and physical defect carpi, compared with that in controls. In MIA-injected joints, there was less articular cartilage fibrillation and erosion, less chondrocyte death, and greater safranin-O staining for glycosaminoglycans in PSG-treated horses. Evaluation of joints in which physical defects were made revealed no differences between control and PSG-injected joints. None of the partial-thickness defects had healed. Full-thickness defects were repaired with fibrous tissue (which was more vascular and cellular in PSG-injected joints) and occasionally small amounts of fibrocartilage. Seemingly, PSG had chondroprotective properties in a model of chemically induced articular cartilage damage, whereas PSG had no obvious effect in a physical articular cartilage-defect model.  相似文献   

Modelling the potential impact of exotic diseases on regional Australia     

MG GARNER  MB LACK 《Australian veterinary journal》1995,72(3):81-87

SUMMARY: Recent international initiatives for disease control suggest that, in the future, the consequences for trade of an exotic disease outbreak may not be as severe as estimated in the past. If zoning were to be accepted by Australia's trading partners, then the major effects may be felt at the regional rather than the national level. A study, using an integrated epidemiological/economic model, was undertaken to compare the impacts of 3 important exotic diseases (foot-and-mouth disease, classical swine fever and sheep pox) in 3 different regions of Australia. The study demonstrated that there are significant differences between the size and effect of different disease outbreaks. Regional factors influence not only the way that the disease will spread and manifest itself, but also the effects on local communities. Foot-and-mouth disease caused more economic losses than sheep pox or classical swine fever. The major determinant of differences in the effects of the diseases between regions was the nature of the regional economies. The less diversified the economy, the greater the effect of an exotic disease outbreak in relation to the size of that economy.  相似文献   

Evaluating the risk of the establishment of screwworm fly in Australia     

MG ATZENI  DG MAYER  MA STUART 《Australian veterinary journal》1997,75(10):743-745

Objective To investigate probabilities of establishment of screwworm fly throughout the year, for several locations around Australias coastline.
Methods A simulation model that predicts the spread and economic impact of an established screwworm fly population was modified to include stochastic survival functions, to investigate the risks of the pest actually establishing in this country. The effects of time of year, climate, vegetation and the number of incoming flies or larvae were investigated for four locations around Australia.
Results Analysis of variance identified a dominant three-way interaction between site, time, and the number of introduced flies. These probabilities are graphed.
Discussion In southern areas, as exemplified by Fremantle, the cold winters limit survival. A high probability of establishment exists year round in tropical regions, except in areas around the Gulf of Carpentaria and in the Northern Territory where dry weather mid-year would limit survival. Despite these comparatively lower risks, there were no areas or times where reductions in quarantine efforts could be justified.  相似文献   

Effects of intra-articular administration of methylprednisolone acetate on normal equine articular cartilage     

G W Trotter  C W McIlwraith  J V Yovich  R W Norrdin  R H Wrigley  C H Lamar 《American journal of veterinary research》1991,52(1):83-87

The effects of the corticosteroid 6-alpha-methylprednisolone acetate on normal equine articular cartilage were evaluated, using the middle carpal joint in 4 clinically normal young horses. One middle carpal joint of each horse was injected 3 times with 100 mg of 6-alpha-methylprednisolone acetate, at 14-day intervals. The opposite middle carpal joint (control) was injected with 2.5 ml of lactated Ringer solution at the same intervals. Effects were studied until 8 weeks after the first injection. Evaluation included clinical and radiographic examination, and gross, microscopic, and biochemical evaluation of joint tissues. Horses remained clinically normal during the study, and significant radiographic changes were not observed. Safranin-0 matrix staining intensity and uronic acid content were significantly (P less than 0.05) lower and hydroxyproline content was significantly (P less than 0.05) higher in articular cartilage of corticosteroid-injected joints vs control joints.  相似文献