MODELING THE EFFECT OF SPATIAL EXTERNALITIES ON INVASIVE SPECIES MANAGEMENT

Changes in production conditions associated with biological invasions can be complex. As a result, modeling invasive species management decisions can be difficult. Modeling these decisions is further compounded by externalities associated with spatial relationships among growers. In order to calculate optimal management decisions, an accurate bioeconomic model of the feedback between grower decisions and the new biological interactions created by an invasive species population is needed. In this paper, a bioeconomic model is used to explicitly analyze how externalities caused by spatial relationships among agricultural producers affect optimal invasive species management decisions. The example of the coordinated greenhouse whitefly management in the Oxnard, CA, area is discussed. This is an interesting example because of the complex cycle of host crops used by the whitefly and the effect this cycle has on the optimal whitefly management decisions for strawberry growers. Three research objectives achieved in this paper include first, using the model to assess how the spatial relationship among growers affects incentives for regional invasive pest management. Second, analyze whether current policies could be adjusted to substitute for coordination among growers. Third, the use of the bioeconomic model to identify factors for this specific case that affect whether or not growers may voluntarily coordinate their management decisions. We find that spatial relationships among growers affect the need for coordination in the strawberry/whitefly case. Whitefly migrations across host crop fields require growers to manage the whitefly on a regional basis in order to maximize strawberry producer welfare. The results also indicate that the amount of effort needed to achieve coordination required is limited; the only requirement is that information related to field management be shared among growers of whitefly host crops. The results from the bioeconomic model describe the biological and economic feedback of the grower's decision which allows policymakers to identify the willingness of producers to coordinate at various times of year. In the Oxnard strawberry/whitefly case, for example, growers will not find it optimal to adjust their application timing for a second immigration of adult greenhouse whiteflies when they occur near the end of the season, such as in May or June, but will for earlier points in the season. Three policy implications of the results from the strawberry/whitefly case are also discussed in the paper. First, adjustments to current policies regulating whitefly management do not remove the need for coordination among growers to them. Also, it was found that current policies do not, by themselves, generate the need for coordination. Finally, the results show it is not always necessary to create a central agency for regional invasive species management.Invasive species, strawberry, greenhouse whitefly, externality, optimal management, Research Methods/ Statistical Methods,

IMPACTS OF PESTICIDE REGULATION ON THE CALIFORNIA STRAWBERRY INDUSTRY

Environmental regulation of agriculture is becoming increasingly important, and growers are increasingly concerned about the effects of regulations on their profitability. Regulations governing the use of a pesticide affect its economic value. Further, growers often face a choice among pesticide alternatives, each with its own set of regulatory restrictions. In this environment, the introduction of a new regulation can have complex effects on growers' profit-maximizing pesticide choices. Buffer zones and regional emissions caps mean that pesticide choices can have important spatial components. Our paper presents an optimization model that incorporates spatial considerations at the field and regional level. We apply our model to fumigant choice by California strawberry growers. The industry is facing an impending ban on the use of methyl bromide, which in conjunction with chloropicrin was the standard fumigant for over forty years. In addition to the forthcoming ban, the state government has imposed regulations governing methyl bromide application, including buffer zones, etc. These extreme use restrictions provide us with an interesting environment for modeling the effects of pesticide regulations. There are currently two legally available fumigants that may substitute for methyl bromide in strawberries: 1,3-D and chloropicrin. 1, 3-D is subject to township caps and other restrictions. Township caps limit total application in an area. The California Department of Pesticide Regulation is currently undertaking air monitoring and other activities to determine whether or not buffer zones and other restrictions should be applied to chloropicrin. We evaluate the effects of current and proposed regulations on field-level decisions and industry costs and returns. Methodology To the best of our knowledge, no study has examined the role of pesticide use regulations in determining growers' profit-maximizing pesticide choices at the field level. We do so by combining three datasets with a field-level spatial model of the profit-maximizing fumigation decision. The first dataset includes detailed field-level information regarding the costs and yields associated with alternative fumigants obtained from a multi-disciplinary research project. The second includes chemical-specific California use regulations regarding treatment rates, buffer zones, and other restrictions. The third includes information on the shapes and sizes of strawberry fields in California. Using these data, the optimization model computes the profit-maximizing treatment for each field including pattern of treatment and number of acres treated per day, etc. Field-level results are aggregated to evaluate the impact of regional pesticide regulations, and then to estimate the industry-level effects of current and proposed pesticide use regulations. We model the effects of the entire regulatory system on the fumigation decisions made by farmers. The restrictions on fumigants are integrated into a field-level programming model of a grower's fumigant decision choice. The program calculates the optimal fumigation plan for a field, given the field's size and shape, and use regulations, and per-acre costs and returns associated with each fumigant. The resulting field-level choices are aggregated in order to check for consistency with township caps. If caps are exceeded, the model is rerun using a number of allocation rules. All choices for all fields are aggregated in order to obtain industry-level results. We perform this procedure for the current set of restrictions and for several alternative sets, assessing the profitability of each alternative. For example, we remove the existing township caps on 1,3-D and evaluate how much the results change. We include varying buffer zone restrictions on chloropicrin, and evaluate whether growers' fumigant choices are sensitive to the size of the buffer zone. Relevance Environmental regulation of agriculture is becoming increasingly important. By explicitly analyzing the effect of regulations affecting methyl bromide alternatives in a model that includes both the spatial dimensions of some regulations and the costs and yields associated with each alternative, we will obtain a more detailed and accurate assessment of the costs of these regulations than is currently available. Our results will provide a greater understanding of the effects of these regulations on industry profitability, and how these regulations interact. Our model can be applied to other cases of pesticide regulations. Given the increasing importance of environmental regulation in agriculture, it is important to aid policymakers in understanding how regulations interact with each other, possibly in unexpected ways.Environmental Economics and Policy,

Развитие творческих способностей учащихся на учебных занятиях по трудовому обучению и на занятиях дополнительного образования

Секция 1. Технический труд и техническое творчеств

Costs of 2001 methyl bromide rules estimated for California strawberry industry

The California Department of Pesticide Regulation (DPR) restricts pesticide use to reduce negative impacts on human health and the environment. The DPR implemented methyl bromide use regulations in 2001. Our study demonstrates that the estimated 2001 costs of these regulations for the California strawberry industry were quite substantial (more than $26 million total), equivalent to roughly 25% of estimated industry returns over total cash costs in 2001. These impacts were unevenly distributed across growers. Growers with small fields in urban areas had higher peracre costs than growers with large fields in agricultural areas

PRICE DETERMINATION IN THE STRAWBERRY MARKET: A REGIONAL ANALYSIS

We estimate five regional price determination models, four for regions in California, and one for Florida. We compare our regional California estimation results to those of an aggregate, state-level model. We use our estimation results to address three questions of interest to the strawberry industry which require a disaggregated analysis.Marketing,

Graphene formation on SiC substrates

Graphene layers were created on both C and Si faces of semi-insulating, on-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum (<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method for H2 etching the on-axis sub-strates was developed to produce surface steps with heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each polytype. A process was developed to form graphene on the substrates immediately after H2 etching and Raman spectroscopy of these samples confirmed the formation of graphene. The morphology of the graphene is described. For both faces, the underlying substrate morphology was significantly modified during graphene formation; sur-face steps were up to 15 nm high and the uniform step morphology was sometimes lost. Mo-bilities and sheet carrier concentrations derived from Hall Effect measurements on large area (16 mm square) and small area (2 and 10 um square) samples are presented and shown to compare favorably to recent reports.Comment: European Conference on Silicon Carbide and Related Materials 2008 (ECSCRM '08), 4 pages, 4 figure

Joint modelling rationale for chained equations.

BACKGROUND: Chained equations imputation is widely used in medical research. It uses a set of conditional models, so is more flexible than joint modelling imputation for the imputation of different types of variables (e.g. binary, ordinal or unordered categorical). However, chained equations imputation does not correspond to drawing from a joint distribution when the conditional models are incompatible. Concurrently with our work, other authors have shown the equivalence of the two imputation methods in finite samples. METHODS: Taking a different approach, we prove, in finite samples, sufficient conditions for chained equations and joint modelling to yield imputations from the same predictive distribution. Further, we apply this proof in four specific cases and conduct a simulation study which explores the consequences when the conditional models are compatible but the conditions otherwise are not satisfied. RESULTS: We provide an additional "non-informative margins" condition which, together with compatibility, is sufficient. We show that the non-informative margins condition is not satisfied, despite compatible conditional models, in a situation as simple as two continuous variables and one binary variable. Our simulation study demonstrates that as a consequence of this violation order effects can occur; that is, systematic differences depending upon the ordering of the variables in the chained equations algorithm. However, the order effects appear to be small, especially when associations between variables are weak. CONCLUSIONS: Since chained equations is typically used in medical research for datasets with different types of variables, researchers must be aware that order effects are likely to be ubiquitous, but our results suggest they may be small enough to be negligible

Apiotrichum terrigenum sp. nov., a novel soil-associated yeast found in both the UK and mainland Europe

Five arthroconidium-producing yeast strains representing a novel Trichosporon-like species were independently isolated from the UK, Hungary and Norway. Two strains (Bio4(T) and Bio21) were isolated from biogas reactors used for processing grass silage, with a third strain (S8) was isolated from soil collected at the same UK site. Two additional strains were isolated in mainland Europe, one from soil in Norway (NCAIM Y.02175) and the other from sewage in Hungary (NCAIM Y.02176). Sequence analyses of the D1/D2 domains of the LSU rRNA gene and internal transcribed spacer (ITS) region indicated that the novel species belongs to the recently reinstated genus Apiotrichum and is most closely related to Apiotrichum scarabaeorum, a beetle-associated species first found in South Africa. Despite having similar physiological characteristics, the two species can be readily distinguished from one another by ITS sequencing. The species name Apiotrichum terrigenum sp. nov. is proposed to accommodate these strains, with Bio4(T) (=CBS 11373(T)=NCYC 3540(T)) designated as the type strain. The Mycobank deposit number is MB817431

Proteomic analyses of Urine Exosomes reveal New Biomarkers of Diabetes in Pregnancy.

ObjectiveTo evaluate 24 hour urine exosome protein content changes among pregnant US subjects with diabetes and obesity during early pregnancy.MethodsThe exosome proteome content from 24 hour urine samples of pregnant subjects with gestational diabetes mellitus (GDM, N=8) and pre-gestational Type 2 diabetes (PGD, N = 10) were compared with control samples (CTRL, N = 10) obtained at week 20 of pregnancy. Differences in exosome protein load between groups was identified by liquid chromatography/mass spectrometry, analyzed by linear regression in negative binomial distribution, visualized in MetaboAnalyst (version 3.0), and validated by western immunoblotting.ResultsAt the 20th week of pregnancy, we identified 646, 734 and 856 proteins in exosomes from 24 hour urine samples of patients from the CTRL, GDM and PGD groups, respectively. S100 calcium binding protein A9, damage associated molecular pattern (DAMP) signal, was found to be significantly increased in both GDM and PGD subjects. In GDM subjects the peptide counts for S100A9 protein independently correlated with maternal obesity and macrosomia of the newborn infants. Early to late pregnancy developmental changes in the GDM group were shown to utilize pathways and protein expression levels differently from those in PGD or CTRL groups.ConclusionsUrinary exosome proteomic analysis non-invasively provides insights into maternal changes during diabetic pregnancy. Exosome biomarkers early in pregnancy can be potentially used to better understand pathophysiologic mechanisms of diabetes at a cellular level, and to distinguish between gestational and pre-gestational diabetes at the pathway level. This information can aid intervention efforts to improve pregnancy outcomes in women with diabetes

Distinct regulation of dopamine D2S and D2L autoreceptor signaling by calcium

D2 autoreceptors regulate dopamine release throughout the brain. Two isoforms of the D2 receptor, D2S and D2L, are expressed in midbrain dopamine neurons. Differential roles of these isoforms as autoreceptors are poorly understood. By virally expressing the isoforms in dopamine neurons of D2 receptor knockout mice, this study assessed the calcium-dependence and drug-induced plasticity of D2S and D2L receptor-dependent G protein-coupled inwardly rectifying potassium (GIRK) currents. The results reveal that D2S, but not D2L receptors, exhibited calcium-dependent desensitization similar to that exhibited by endogenous autoreceptors. Two pathways of calcium signaling that regulated D2 autoreceptor-dependent GIRK signaling were identified, which distinctly affected desensitization and the magnitude of D2S and D2L receptor-dependent GIRK currents. Previous in vivo cocaine exposure removed calcium-dependent D2 autoreceptor desensitization in wild type, but not D2S-only mice. Thus, expression of D2S as the exclusive autoreceptor was insufficient for cocaine-induced plasticity, implying a functional role for the co-expression of D2S and D2L autoreceptors