Estimating evapotranspiration from processing tomato using the surface renewal technique     

Rafael Rosa  Uri Dicken  Josef Tanny 《Biosystems Engineering》2013,114(4):406-413

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Estimating olive leaf nitrogen concentration using visible and near-infrared spectral reflectance     

Nativ Rotbart  Zeev Schmilovitch  Yafit Cohen  Victor Alchanatis  Ran Erel  Timea Ignat  Clara Shenderey  Arnon Dag  Uri Yermiyahu 《Biosystems Engineering》2013,114(4):426-434

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Mitsuokella jalaludinii inhibits growth of Salmonella enterica serovar Typhimurium     

Levine UY  Bearson SM  Stanton TB 《Veterinary microbiology》2012,159(1-2):115-122

Salmonella continues to be a significant human health threat, and the objective of this study was to identify microorganisms with the potential to improve porcine food-safety through their antagonism of Salmonella. Anaerobic culture supernatants of 973 bacterial isolates from the gastrointestinal tract and feces of swine were screened for their capacity to inhibit the growth of Salmonella enterica serovar Typhimurium. Growth inhibition of 1000-fold or greater was observed from 16 isolates, and 16S rRNA sequencing identified the isolates as members of the genera Mitsuokella, Escherichia/Shigella, Anaerovibrio, Selenomonas, and Streptococcus. Four isolates were identified as Mitsuokella jalaludinii, and the mechanism of Salmonella Typhimurium growth inhibition by M. jalaludinii was further investigated. M. jalaludinii stationary phase culture supernatants were observed to significantly inhibit growth, and featured the production of lactic, succinic, and acetic acids. Aerobic and anaerobic S. Typhimurium growth was restored when the pH of the culture supernatants (pH 4.6) was increased to pH 6.8. However, S. Typhimurium growth in fermentation acid-free media was the same at pH 4.6 and pH 6.8 - indicating a synergistic effect between fermentation acid production and low pH as the cause of S. Typhimurium growth inhibition. Furthermore, exposure of S. Typhimurium to M. jalaludinii culture supernatants inhibited Salmonella invasion of HEp-2 cells by 10-fold. The results identify M. jalaludinii as a possible inhibitor of Salmonella growth and invasion in swine, and thus a potential probiotic capable of improving food safety.  相似文献   

A regret function for agricultural production systems     

Ilan Amir  Uri Shamir  Robert S. Broughton 《Agricultural Systems》1980,6(2):81-91

Decision-making under uncertainty is a difficult task, involving risks. Since losses are to be expected although not necessarily through the decision-maker's fault, a regret concept is adopted. A regret concept and a regret function, based on a linear programming model, are suggested, using analysis of the sensitivity of the optimal plan to changes in random prices and in the amounts of available resources and estimates of the probabilities that each of the random variables will drop below a critical value. The use of this regret function, as an aid in decision-making, to evaluate the plan at the planning stage is explained and clarified by examples and a case study.  相似文献   

Analysis and assessment of precipitation chemistry at Caribou,Maine     

R. S. Artz  Uri Dayan 《Water, air, and soil pollution》1986,30(3-4):845-855

Over the last 30 yr, Caribou, Maine has been the only U.S. collection site which has been a part of all four national precipitation chemistry networks. Due to its remote but strategically important location, the data from this site are very useful in evaluating transboundary transport of the major ions present in precipitation. This paper assesses the reliability of the Caribou data base and looks at the more recent data with the aid of the GAMBIT (Gridded Atmospheric Multilevel Backward Isobaric Trajectory) model. An examination of the historical data base indicates serious contamination problems in pre-1980 samples, particularly with S0₄ measurements. The trajectory climatology shows that the largest number of precipitation events track along the U.S. coast. Preliminary chemistry measurements indicate highest concentrations of H+ and S0₄ occur from events associated with trajectories passing through southern Canada.  相似文献   

Spatial distribution of water status in irrigated olive orchards by thermal imaging   总被引：1，自引：0，他引：1  

Nurit Agam  Eran Segal  Aviva Peeters  Asher Levi  Arnon Dag  Uri Yermiyahu  Alon Ben-Gal 《Precision Agriculture》2014,15(3):346-359

Information regarding tree water status in irrigated olive orchards is essential for managing growth to optimize yields and olive oil quality. One management practice option is to monitor or sample individual trees and use this information for orchard-scale management. This study assessed the ability of thermal imaging to provide the spatial distribution and variability of tree water status in a commercial irrigated olive orchard, and described strategies and a procedure for choosing which individual trees best represent the orchard. The study employed gradual upscaling from individual trees grown in lysimeters, through a controlled experimental field plot, to a commercial orchard. Thermal imaging of olive trees grown in lysimeters attested the sensitivity of the technique to identify mild-level water stress by correlating crown temperatures to stem water potential. Knowledgeable choice of five or ten representative trees in the experimental plot, based on the histogram distribution obtained for the entire experimental orchard, lead to successful reconstruction of the spatial distribution of canopy temperature, and thus of water status. Positively skewed distributions of crown temperatures found in both the field plot and commercial orchard suggested distinct patterns, where the canopy temperature of the majority of the trees was lower than the average, and a relatively small number of trees had significantly higher temperatures and suggest commercial practicality of the proposed methodology. Thermal imaging can therefore serve as a useful tool for determining representative trees that, if frequently monitored, or instrumented with continuous water status sensors, can provide important information for orchard water management.  相似文献   

Fine-root rhizosphere and morphological adaptations to site conditions in interaction with tree mineral nutrition in young silver birch (<Emphasis Type="Italic">Betula pendula</Emphasis> Roth.) stands     

Katrin Rosenvald  Ivika Ostonen  Marika Truu  Jaak Truu  Veiko Uri  Aivo Vares  Krista Lõhmus 《European Journal of Forest Research》2011,130(6):1055-1066

Limited nutrient acquisition from soil is a key process limiting productivity in boreal forest. We investigated short-root morphological adaptations and rhizosphere effect in relation to site conditions in interaction with tree mineral nutrition. We studied seven young (8- to 14-year-old) silver birch (Betula pendula Roth.) stands on abandoned agricultural land in Estonia. Soil pH varied from 3.8 to 7.0, and soil N % from 0.07 to 0.26%. Tree nutrient (NPK) status was expressed by leaf nutrient concentrations. Leaf N correlated negatively with short-root specific length and area. Summed activity (SA) and metabolic diversity of bacteria (by BIOLOG Ecoplate™), bacterial community diversity (by DGGE) and pH_KCl were determined for rhizosphere (R) and bulk soil (S) to reveal the extent of the rhizosphere effect. Bacterial activity in rhizosphere was 1.4–4.7 times higher than in bulk soil. Ratio SA_R/SA_S indicating root support to the rhizosphere bacterial communities decreased with increasing bulk soil pH; however, when bulk soil pH was ≥5, the decrease in SA_R/SA_S was insignificant, i.e. the rhizosphere effect stayed at a stable level. Diversity of bacterial community was 6% higher in bulk soil than in rhizosphere. Rhizosphere acidification occurred in studied stands when bulk soil pH_KCl ≥ 5. Short-root N % correlated positively with SA_R/SA_S. We concluded that tree N-nutritional status was related to short-root morphological parameters but not to studied microbiological characteristics in the soil of young silver birch stands.  相似文献   

Fluidity of bound hydration layers     

Raviv U  Klein J 《Science (New York, N.Y.)》2002,297(5586):1540-1543

We have measured the shear forces between solid surfaces sliding past each other across aqueous salt solutions, at pressures and concentrations typical of naturally occurring systems. In such systems the surface-attached hydration layers keep the compressed surfaces apart as a result of strongly repulsive hydration forces. We find, however, that the bound water molecules retain a shear fluidity characteristic of the bulk liquid, even when compressed down to films 1.0 +/- 0.3 nanometer thick. We attribute this to the ready exchange (as opposed to loss) of water molecules within the hydration layers as they rub past each other under strong compression.  相似文献