Evaluation of a Geonics EM31-3RT probe to delineate hydrologic regimes in a tile-drained field     

H. Dadfar  R. J. Heck  G. W. Parkin  K. Barfoot-Kinsie 《Precision Agriculture》2011,12(5):623-638

A world-wide need to use water resources efficiently necessitates more effective approaches to study water and contaminant transport in soil. This study examined the effectiveness of a multi-receiver electromagnetic induction probe (Geonics EM31-3RT) and modeling software (EMIGMA) to delineate hydrological regimes at field scale. The site consisted of 20 (15 m × 15 m) tile-drained plots in Southern Ontario, Canada. Measurements of apparent soil electrical conductivity (EC_a) and magnetic susceptibility were obtained using the EM31-3RT in each plot at four distances (0, 2.25, 4.5 and 7.5 m) from the tile drain, and on three occasions (August 22, 26 and 29) in 2003. The EMIGMA was used to simulate a depth profile of electrical conductivity (EC_s) from EM31-3RT readings. The near-surface soil showed significantly (p < 0.01) smaller EC_a values than at greater depth. The EC_a measurements made directly over the tile drains were smaller than those observed further away due to the presence of the drains. Cluster analysis indicated that the largest EC_a values were at the lower elevations of the site related to the redistribution of moisture from higher elevations. The effect of tile drains and rainfall events on EC_a was simulated well by EMIGMA, with smaller EC_s values above the drains compared to further away, and showing an increase in EC_s in the near-surface soil after rain. This study suggests that EM31-3RT measurements combined with EMIGMA simulation of electrical conductivity can provide valuable information on depth profiles of EC_a and water dynamics in soil.  相似文献   

DNA- and RNA-derived assessments of fungal community composition in soil amended with sewage sludge rich in cadmium, copper and zinc   总被引：2，自引：0，他引：2  

Ian C. Anderson  Pamela I. Parkin  Colin D. Campbell 《Soil biology & biochemistry》2008,40(9):2358

Current UK legislation permits the application of sewage sludge to agricultural land provided concentrations of heavy metals in soil do not increase above maximum permissible limits. However, even within the defined limits, we do not know how an increase in soil heavy metal concentrations is likely to affect biological diversity and activity. Here we report on the effects of sewage sludge addition, including sludge rich in the metals cadmium, copper and zinc, on soil fungal community composition using both an rDNA and rRNA DGGE approach. Sewage sludge addition altered fungal ITS-DGGE banding patterns, however, there were no additional effects of an increase in soil heavy metal concentrations. Similar results were obtained for the full range of copper rich sludge treatments even when copper concentrations were well above the maximum permissible limits. Our data therefore demonstrate that although an increase in soil organic matter content alters soil fungal community diversity and composition, increasing soil concentrations of cadmium, copper and zinc up to current legislative limits had little additional effect regardless of whether rRNA or rDNA was analysed. This suggests that current UK limits for these three heavy metals are within a concentration range that the dominant soil fungi at this field site can tolerate.  相似文献   

The magnetic stability of spin-dependent tunneling devices     

S Gider  B Runge  AC Marley  SSP Parkin 《Science (New York, N.Y.)》1998,281(5378):797-799

The tunneling resistance between two ferromagnetic metal layers that are separated by a thin insulator depends on the relative orientation of the magnetization M of each layer. In a memory device, independent switching of the magnetically soft layer is achieved by making the other layer either exchange-biased or magnetically hard. The repeated reversal of M of the soft layer by field cycling can demagnetize the other magnetically hard layer and thus erase the tunnel junction's memory. The M of exchange-biased structures was stable at least to 10(7) cycles, whereas in hard structures, M generally decayed logarithmically with the number of field cycles. The decay was very sensitive to the thickness of the hard layer and the composition of the soft layer. However, no decay was observed when the moment reversal was accomplished by coherent rotation, establishing that demagnetization results from the formation and motion of domain walls in the soft layer during field cycling.  相似文献   

Ribotype analysis of Corynebacterium pseudotuberculosis isolates from sheep and goats     

SS SUTHERLAND  RA HART  NB BULLER 《Australian veterinary journal》1993,70(12):454-456

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Comparison of tiletamine-zolazepam-ketamine and tiletamine-zolazepam-ketamine-xylazine anaesthesia in sheep     

HC LIN  SS WALLACE  JW TYLER†  RL ROBBINS  JC THURMON‡  DF WOLFE 《Australian veterinary journal》1994,71(8):239-242

Summary The anaesthetic effects of intravenous tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg (TK) and tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg-xylazine 0.11 mg/kg (TKX) were evaluated in six wethers. Heart rate, respiration rate, arterial blood pressure, and the electrocardiogram were monitored during anaesthesia. Analgesia was tested by electrical stimulation in the left flank. Atropine (0.03 mg/kg) was given intramuscularly before induction, but after recording of baseline heart rate and respiratory rate. The duration of analgesia was 28.7 ± 6.9 min with TK and 82.8 ± 26.6 min with TKX. Heart rate increased significantly within 5 min after TK or TKX administration. Respiratory rate remained unchanged after TK administration, but increased significantly from 5 to 45 min after TKX administration. Arterial blood pressure decreased significantly at 15 min with TK and 30 min with TKX. Sheep remained recumbent for 201 min with TK and 166 min with TKX. All recovered uneventfully. We conclude that either TK or TKX may be used for anaesthetising sheep.  相似文献   

The use of race winnings, ratings and a performance index to assess the effect of thermocautery of the soft palate for treatment of horses with suspected intermittent dorsal displacement. A case-control study in 110 racing Thoroughbreds     

Reardon RJ  Fraser BS  Heller J  Lischer C  Parkin T  Bladon BM 《Equine veterinary journal》2008,40(5):508-513

REASONS FOR PERFORMING THE STUDY: There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP). OBJECTIVE: To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study. HYPOTHESIS: Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related. METHODS: The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model. RESULTS: The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation. CONCLUSIONS: Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP. POTENTIAL RELEVANCE: Production of a reliable measure of racehorse performance may be possible.  相似文献   

Proportion of nonsteroidal anti-inflammatory drug prescription in equine practice     

M. Duz  J. F. Marshall  T. D. Parkin 《Equine veterinary journal》2019,51(2):147-153

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The Anti‐Müllerian Hormone Profile is Linked with the In Vitro Embryo Production Capacity and Embryo Viability after Transfer but Cannot Predict Pregnancy Outcome          下载免费PDF全文

N Ghanem  JI Jin  SS Kim  BH Choi  KL Lee  AN Ha  SH Song  IK Kong 《Reproduction in domestic animals》2016,51(2):301-310

The current study investigated the possibility of using the AMH concentration as a predictor of the ability of Korean Hanwoo cows to produce cumulus‐oocyte complexes, embryos that survive after transfer as well as the pregnancy outcome of surrogates. Eight sessions of ovum pick‐up (OPU) were performed with 19 donor cows at an interval of 3–4 days. Antral follicle count (AFC), oocyte quality and in vitro embryo development were recorded for each cow. Embryos produced from cows with different AMH profiles were transferred into recipients (n = 96). Cows in the high (≥0.25 ng/ml) and intermediate (0.1≥ to <0.25 ng/ml) AMH groups had a significantly higher AFC per OPU session (20.40 ± 1.36 and 16.91 ± 1.52, respectively; mean ± standard deviation) than cows in the low AMH group (<0.1 ng/ml; 12.19 ± 2.14). In addition, more cumulus‐oocyte complexes per donor were recovered in the high (11.46 ± 1.22) and intermediate (7.38 ± 0.83) AMH groups than in the low AMH group (4.77 ± 0.44). The percentage of oocytes reached blastocyst stage was significantly higher in the intermediate (47.0%) and high (38.5%) AMH groups than in the low AMH group (32.3%). The number of embryos produced per cow was higher in the high (3.9 ± 0.2) and intermediate (6.9 ± 0.6) AMH groups than in the low AMH group (2.2 ± 0.3). The percentage of embryos that gave birth to viable calves when transferred into recipients was higher for those derived from cows in the intermediate AMH group (50.7%) than for those derived from cows in the low (35.7%) and high (36.4%) AMH groups. In conclusion, a single measurement of AMH concentration predicted the in vitro embryo production potential of donor Korean native cows before OPU and is linked with embryo viability after transfer into recipients.  相似文献   

β-carboline derivatives and diphenols from soy sauce are in vitro quinone reductase (QR) inducers     

Li Y  Zhao M  Parkin KL 《Journal of agricultural and food chemistry》2011,59(6):2332-2340

A murine hepatoma (Hepa 1c1c7) cellular bioassay was used to guide the isolation of phase II enzyme inducers from fermented soy sauce, using quinone reductase (QR) as a biomarker. A crude ethyl acetate extract, accounting for 8.7% of nonsalt soluble solids of soy sauce, was found to double relative QR specific activity at 25 μg/mL (concentration required to double was defined as a "CD value"). Further silica gel column fractionation yielded 17 fractions, 16 of which exhibited CD values for QR induction of <100 μg/mL. The four most potent fractions were subfractionated by column and preparative thin layer chromatography, leading to the isolation and identification of two phenolic compounds (catechol and daidzein) and two β-carbolines (flazin and perlolyrin), with respective CD values of 8, 35, 42, and 2 μM. Western blots confirmed that the increases in QR activity corresponded to dose-dependent increases in cellular levels of NAD[P]H:quinone oxidoreductase 1 protein by these four QR inducers. To the authors' knowledge, this is the first report on the ability of β-carboline-derived alkaloids to induce phase II enzymes.  相似文献   

Gas chromatograph analysis on closed nitrous oxide and air atmospheres of recalcitrant Quercus alba seeds     

Valasia Iakovoglou  Timothy B. Parkin  Richard B. Hall  Manjit K. Misra 《Scandinavian Journal of Forest Research》2014,29(5):415-420

Storage of recalcitrant seeds remains an unsolved problem. The study of gaseous atmospheres could provide insights in understanding the metabolism of recalcitrant seeds and their potential in being used as means for storage. This study investigated the metabolism of the recalcitrant Quercus alba seeds when subjected under nitrous oxide (N₂O) and air atmospheres. Seeds were placed in sealed atmospheric flasks of 98/2% N₂O/O₂. Three experiments were conducted to determine N₂O uptake in relation to oxygen (O₂) and carbon dioxide (CO₂) levels. For the first experiment, “non-renewed” closed atmospheric systems with 98/2% N₂O/O₂ and air were used. Two more experiments were also conducted for the 98/2% N₂O/O₂ atmosphere to determine how rate of gas renewal (two and seven days) affects the N₂O, O₂, and CO₂ gases quantitatively. Cumulative results on non-renewed flasks with 98/2% N₂O/O₂ showed that as time progressed, N₂O uptake increased with variation in the magnitude of N₂O utilization throughout the 37 experimental days, while seeds ceased O₂ utilization by the 11th day. However, CO₂ levels did not decrease, suggesting a shift toward fermentation processes. Finally, the two experiments for the 98/2% N₂O/O₂ indicated that the O₂ levels did not deplete under a two-day gas renewal, suggesting a frequent gas renewal under low O₂ storage conditions.  相似文献