This paper explores Wittgenstein＇s early work as it relates to emerging philosophical problems in ecological modeling. Here I use his thought to structure a logical framework from which to discuss ecological simulati...This paper explores Wittgenstein＇s early work as it relates to emerging philosophical problems in ecological modeling. Here I use his thought to structure a logical framework from which to discuss ecological simulation models in a way that captures how these dynamic representations describe a world from which we can draw logical inferences about real-world ecological processes. I argue that Wittgenstein＇s Tractatus Logico-Philosophicus provides a way of reading problems that arise in using simulation as a way to make inferences about the world. Conversely, ecological simulation provides an illustration of a Tractarian system, because the digital world it creates completely describes and is defined by the programing language. This reading is a novel, but productive, way that notes that the language used in modeling requires a hermeneutical approach to make inferences about modeling/real-world relationships.展开更多
Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils o...Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils of Pakistan with low soil organic carbon(SOC).Lysimeter and field studies were conducted with and without manure application at two irrigation levels in a wheat-fallowmaize rotation in Faisalabad,Punjab,Pakistan.Isoproturon was applied to wheat 55 d after sowing at 1 kg active ingredient(a.i.)ha^(-1),while atrazine was sprayed on maize 30 d after sowing at 0.774 kg a.i.ha^(-1).Soil was sampled from three depths(0-35,35-70,and 70-110 cm) for the field study and four depths(0-35,35-70,70-115,and 115-160 cm) for the lysimeter study,280 and 65 d after application of isoproturon and atrazine,respectively.The soil-water partition coefficients(K_d) of isoproturon and atrazine ranged from 0.3 to 1.2 and 0.4 to 1.5 L kg^(-1),respectively,and increased linearly with increase in SOC contents.The organic carbon-normalized soil-water partition coefficient(K_(oc)) of isoproturon and atrazine averaged 246.1 and 184.9 L kg^(-1),respectively,being higher with low spiking concentration.Isoproturon residues measured 280 d after application ranged from 2.1% to 3.6% of the applied mass in the lysimeter study and from 1.5% to 3.1% under field conditions.Atrazine residues 65 d after application ranged from only 0.62% to 0.78% and from 0.88% to 0.82% in the lysimeter and field studies,respectively.The lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure-amended soil.A pesticide leaching risk screening tool,the ground water ubiquity score(GUS),indicated that in the absence of manure under both irrigation levels,isoproturon has a leaching potential(GUS = 2.8),while with the application of manure it has a very low leaching risk.Atrazine GUS ranged from 1.7 to 1.9,indicating a very low risk of leaching.展开更多
文摘This paper explores Wittgenstein＇s early work as it relates to emerging philosophical problems in ecological modeling. Here I use his thought to structure a logical framework from which to discuss ecological simulation models in a way that captures how these dynamic representations describe a world from which we can draw logical inferences about real-world ecological processes. I argue that Wittgenstein＇s Tractatus Logico-Philosophicus provides a way of reading problems that arise in using simulation as a way to make inferences about the world. Conversely, ecological simulation provides an illustration of a Tractarian system, because the digital world it creates completely describes and is defined by the programing language. This reading is a novel, but productive, way that notes that the language used in modeling requires a hermeneutical approach to make inferences about modeling/real-world relationships.
基金funded by the Higher Education Commission of Pakistan under Indigenous 5000-Fellowship Program(PIN,No.063171189Av3-077)International Research Support Initiative Program(IRSIP,No.1-8/HEC/HRD/2009/671),University of Minnesota,USA
文摘Pesticide leaching is a great threat in low organic carbon soils when subjected to improper irrigation scheduling.Limited data are available on the sorption and leaching potential of pesticides in agricultural soils of Pakistan with low soil organic carbon(SOC).Lysimeter and field studies were conducted with and without manure application at two irrigation levels in a wheat-fallowmaize rotation in Faisalabad,Punjab,Pakistan.Isoproturon was applied to wheat 55 d after sowing at 1 kg active ingredient(a.i.)ha^(-1),while atrazine was sprayed on maize 30 d after sowing at 0.774 kg a.i.ha^(-1).Soil was sampled from three depths(0-35,35-70,and 70-110 cm) for the field study and four depths(0-35,35-70,70-115,and 115-160 cm) for the lysimeter study,280 and 65 d after application of isoproturon and atrazine,respectively.The soil-water partition coefficients(K_d) of isoproturon and atrazine ranged from 0.3 to 1.2 and 0.4 to 1.5 L kg^(-1),respectively,and increased linearly with increase in SOC contents.The organic carbon-normalized soil-water partition coefficient(K_(oc)) of isoproturon and atrazine averaged 246.1 and 184.9 L kg^(-1),respectively,being higher with low spiking concentration.Isoproturon residues measured 280 d after application ranged from 2.1% to 3.6% of the applied mass in the lysimeter study and from 1.5% to 3.1% under field conditions.Atrazine residues 65 d after application ranged from only 0.62% to 0.78% and from 0.88% to 0.82% in the lysimeter and field studies,respectively.The lowest levels of residues for both pesticides were observed with frequent irrigation applied to manure-amended soil.A pesticide leaching risk screening tool,the ground water ubiquity score(GUS),indicated that in the absence of manure under both irrigation levels,isoproturon has a leaching potential(GUS = 2.8),while with the application of manure it has a very low leaching risk.Atrazine GUS ranged from 1.7 to 1.9,indicating a very low risk of leaching.
