Value of chlortetracycline and sulfamethazine for conditioning feeder cattle after transit   总被引：1，自引：0，他引：1  

T W Perry  W M Beeson  M T Mohler  R B Harrington 《Journal of animal science》1971,32(1):137-140

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Temporal and spatial dynamics of insecticide resistance in Myzus persicae (Hemiptera: Aphididae)     

Foster SP  Harrington R  Dewar AM  Denholm I  Devonshire AL 《Pest management science》2002,58(9):895-907

Advances in understanding insecticide resistance in the peach-potato aphid, Myzus persicae (Sulzer), at the genotypic, biochemical and molecular levels have led to rapid and precise methods for the detection of several resistance mechanisms (elevated carboxylesterase, modified acetylcholinesterase or MACE, and knockdown resistance or kdr) in individual insects, and for monitoring their frequencies over space and time. This paper summarises the results of two long-term surveys of resistance dynamics in M persicae in England, based on samples collected directly from field and glasshouse crops or from four 12.2-m suction traps. The study showed marked fluctuations in resistance frequencies that probably reflect the counteracting forces of selection imposed by insecticides for aphids possessing more copies of esterase resistance genes, and selection against these forms when insecticide use is relaxed. There is growing evidence that several different resistance mechanisms in M persicae have associated fitness costs. In the case of esterase and MACE, these costs are apparently strong enough to effect a decline in resistance frequency over winter, and a more prolonged decline over successive cropping seasons when aphid numbers are insufficient to trigger intensive chemical applications. Changes in the overall frequency of resistance genotypes may also be influenced by the predominance of year-round parthenogenesis in M persicae in the UK, leading to non-random associations between mechanisms and selection operating on clonal lineages rather than individual genotypes.  相似文献   

Influences of Cropping Practices on Verticillium dahliae Populations in Commercial Processing Tomato Fields in Ontario     

Harrington MA  Dobinson KF 《Phytopathology》2000,90(9):1011-1017

ABSTRACT The abundance of Verticillium dahliae in the soil and the incidence of V. dahliae-infected plants were determined for 12 commercial processing tomato fields in Kent County, Ontario. Comparison of the data with those from a previous survey of fields in adjacent Essex County showed that soil inoculum levels and incidence of infection were generally lower in Kent County fields and that race 2 V. dahliae was not common in Kent County. From the two counties, 128 isolates were characterized by restriction fragment length polymorphism (RFLP) analysis, using the subspecies-specific repetitive DNA sequence E18. A subset of these isolates was also characterized by vegetative compatibility and DNA hybridization analysis with a second subspecies-specific DNA sequence. Isolates with E18 RFLP profiles highly similar to those of isolates previously collected from potato fields in North America were prevalent in Essex County tomato fields but not common in Kent County fields. The data are consistent with the hypothesis that the group I isolates were introduced into southwestern Ontario with potato and that the different cultural practices in Essex County and Kent County have contributed to the differences in the accumulation of these isolates in the two regions.  相似文献   

Retrospective study of the prevalence of keratoconjunctivitis sicca in diabetic and nondiabetic dogs after phacoemulsification          下载免费PDF全文

Anne J. Gemensky‐Metzler  Jennifer E. Sheahan  Paivi J. Rajala‐Schultz  David A. Wilkie  Jay Harrington 《Veterinary ophthalmology》2015,18(6):472-480

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Variable-density thinning promotes differential recruitment and development of shade tolerant conifer species after 17 years     

Willis  John L.  Harrington  Constance A.  Brodie  Leslie C.  Roberts  Scott D. 《New Forests》2021,52(2):329-348

Promoting patchy recruitment of shade tolerant tree species into the midstory is an important step in developing structural diversity in second-growth stands. Variable-density thinning (VDT) has been proposed as a strategy for accelerating structural diversity, as its combination of within-stand treatments (harvest gaps, thinning, and non-harvested skips) should create variable overstory and understory conditions. Here we report on western hemlock (Tsuga heterophylla (Raf.) Sarg.) seedling and sapling densities in five mixed-conifer stands and Sitka spruce (Picea sitchensis (Bong.) Carr.) seedling and sapling densities in two stands in western Washington at 3,7, 10, and 16–17 years after VDT. Additionally, we report on western hemlock advance regeneration growth and survival in two stands over 14 years. Western hemlock seedling density was highest in the thinned treatment but only significantly so in Year 10. In contrast, the gaps contained significantly more western hemlock saplings in Years 7 and 10 and significantly greater growth of western hemlock advance regeneration through Year 10. Skips embedded within the VDT did not differ significantly from unharvested reserves in terms of seedling or sapling densities of either species. Sitka spruce seedling density was highest in the gap and thinned treatments, but saplings were uncommon in all treatments. Collectively, these results indicate that our variant of VDT promoted patchy, midstory recruitment of western hemlock but failed to recruit Sitka spruce saplings in either stand where it established. Consequently, more intensive variants of VDT may be required to promote midstory recruitment of species less tolerant of shade than western hemlock.

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Malunion of an in utero open tibial fracture in an aborted equine fetus     

Diane Murdaugh DVM  PhD  Richard I. Miller BVSc  PhD  David R. Harrington DVM  Louis L. Martin DVM 《Journal of Equine Veterinary Science》1985,5(4):189-191

An in utero tibial fracture was examined at necropsy in a seven-month-old male aborted Thoroughbred fetus. Grossly the healed fracture had a smooth cortical surface. Histologically there was no callus formation or excessive osteoclastic or osteoblastic activity.  相似文献   

Soil carbon and nutrient pools in Douglas-fir plantations 5 years after manipulating biomass and competing vegetation in the Pacific Northwest     

Robert A. Slesak  Stephen H. SchoenholtzTimothy B. Harrington 《Forest Ecology and Management》2011,262(9):1722-1728

We assessed changes in mineral soil total carbon (C) and nutrient (exchangeable Ca, K, Mg, and total N) pools to 60 cm depth 5 years after manipulating biomass and competing vegetation at two contrasting Douglas-fir plantations (Matlock, WA, and Molalla, OR). Biomass treatments included whole-tree (WT) and bole-only (BO) harvest, and competing vegetation control (VC) treatments were applied as either initial or annual herbicide applications. There were main effects of biomass removal and VC on the absolute change in soil pools of some elements at both sites, but significant effects were more prevalent at the lower soil quality Matlock site than the Molalla site, and were generally confined to the top 15 cm of soil. In all cases, treatment effects were associated with increases in C and nutrients following BO and initial VC treatments combined with little change in soil pools following WT and annual VC treatments. At the Matlock site, total soil pools (0-60 cm) of C, N, and Ca significantly increased in the BO and initial VC treatments, and Mg increased and K decreased regardless of treatment. At the Molalla site, soil C and nutrient pools did not change in response to treatments, but total soil Mg increased in all treatments during the study period. Correlation analyses indicated little influence of soil nutrient pools on early growth at Matlock likely because soil water is more limiting than nutrient availability at that site, but vegetation growth was correlated to nutrient pools at Molalla indicating changes in pools associated with harvesting and treatment could influence crop development in the future. These early results indicate low potential for intensive management practices to reduce mineral soil pools of C and nutrients, but there is uncertainty on the long-term growth response because treatments may have influenced nutrient storage in pools other than mineral soil.  相似文献   

Outbreak of West Nile virus in North America     

Spielman A  Andreadis TG  Apperson CS  Cornel AJ  Day JF  Edman JD  Fish D  Harrington LC  Kiszewski AE  Lampman R  Lanzaro GC  Matuschka FR  Munstermann LE  Nasci RS  Norris DE  Novak RJ  Pollack RJ  Reisen WK  Reiter P  Savage HM  Tabachnick WJ  Wesson DM 《Science (New York, N.Y.)》2004,306(5701):1473-5; author reply 1473-5

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Brain blood flow: alteration by prior exposure to a learned task   总被引：1，自引：0，他引：1  

S C Bondy  M E Harrington 《Science (New York, N.Y.)》1978,199(4326):318-319

Chicks with the eyelids of one eye sutured were trained to discriminate between grains and pebbles. The learned experience was completely recognizable by the naive eye that had been occluded during training. When both eyes were opened after monocular training, the velocity of blood flow through paired left and right brain regions was identical. However, when chicks were reexposed to the discrimination situation, blood flow through the cerebral hemisphere associated with the naive eye was greater than that through the hemisphere associated with the trained eye.  相似文献   

VALUE OF CHARACTERS OF THE UNDEVELOPED SHOOT IN IDENTIFYING PLANTS     

Harrington HD 《Science (New York, N.Y.)》1939,90(2329):157-158

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