1,721,019 research outputs found
New perspectives for the application of bioplastic materials in the biocontrol of Aspergillus flavus in corn
No full textMycotoxins are secondary metabolites produced by certain filamentous fungi that can contaminate a large variety of agricultural commodities before and after harvest. Among different mycotoxins, aflatoxins and especially aflatoxin B1 are of particular concern because they are potent natural carcinogens. Aflatoxin-producing fungi, mainly Aspergillus flavus and A. parasiticus, are ubiquitous, being commonly isolated from agricultural soil and crop debris. Although many aspects of the ecology of aflatoxin-producing fungi have been elucidated, control of aflatoxin contamination of agricultural crops remains a difficult task. Agronomical practices promoting general plant health have shown variable and more frequently limited success in preharvest control of aflatoxin contamination. Competitive replacement of indigenous toxigenic soil isolates is considered a more promising and effective approach. This biocontrol strategy is based on field application of a large number of propagules of nontoxigenic strains of A. flavus. Biocontrol strains are typically formulated as inoculated or spore-coated grain seeds. More recently, efforts to explore new approaches and technologies have resulted in the development of other practical solutions, including a bioplastic-based formulation. This formulation originally developed in 2008, consists of bioplastic granules entrapping spores of the nontoxigenic biocontrol strain, A. flavus NRRL 30797. Laboratory and field studies that have been conducted until now have clearly shown that granules of the starch-based bioplastic Mater-Bi® are effective in delivering this biocontrol strain. In addition to having a satisfactory shelf life, the granules are easy to prepare, handle, and apply to agricultural fields. More importantly, this novel bioplastic formulation is capable of efficiently reducing aflatoxin contamination of corn. The bioplastic Mater-Bi® can also have other applications. For instance, rods or granules prepared using a slightly modified Mater-Bi® bioplastic matrix can be used to selectively isolate A. flavus from soil and corn kernels. © 2011 Informa Healthcare USA, Inc
Coverage-based rewriting for data preparation
No full textThe development of technological solutions satisfying non discriminating requirements is currently one of the main challenges for data processing. Concepts like fairness, i.e., lack of bias, and diversity, i.e., the degree to which different kinds of objects are represented in a dataset, have been recently taken into account in designing non-discriminating set selection, ranking, and OLAP approaches. Information extraction is however also at the basis of back-end data processing, for preparing, e.g., extracting and transforming data, usually based on SQL queries, before loading them inside a data warehouse for further front-end processing. The impact of an unfair data preparation process might have a relevant impact on front-end analysis. As an example, an underrepresented category in the warehouse might lead to an underrepresentation of that category in most of the following processes. This kind of guarantee is known as coverage. In this paper, we start from this consideration and we propose an approach for automatically rewriting back-end queries, whose results do not guarantee some coverage constraints, into the "closest" queries satisfying those constraints. Through rewriting, coverage-based modifications of data preparation steps are traced for further processing. We also present some preliminary experimental results and we identify some directions for future works
Coverage-based Queries: Nondiscrimination Awareness in Data Transformation
No full textWhen people-related data are used in automated decision making processes, social inequities can be amplified. Thus, the development of technological solutions satisfying nondiscrimination requirements, in terms of, e.g., fairness, diversity, and coverage, is currently one of the main challenges for the data management and data analytics communities. In particular, coverage constraints guarantee that a dataset includes enough items for each (protected) category of interest, thus increasing diversity with the aim of limiting the introduction of bias during the next analytical steps. While coverage constraints have been mainly used for designing data repair solutions, in our study we investigate their effects on data processing pipelines, with a special reference to data transformation. To this aim, we first introduce coverage-based queries as a means for ensuring coverage constraint satisfaction on a selection-based query result, through rewriting. We then present two approximate algorithms for coverage-based query processing: the first, covRew, initially introduced in [3], relies on data discretization and sampling; the second, covKnn is a novel contribution and relies on a nearest neighbour approach for coverage-based query processing. The algorithms are experimentally compared with respect to efficiency and effectiveness, on a real dataset
Degradation and side effects of three sulfonylurea herbicides in soil
No full textSoil degradation and side effects of triasulfuron [3-(6-methoxy-4-methyl-1,3,5-triazin-2-yl)-1-(2-(2-chloroethoxy) phenylsulfonyl)-urea], primisulfuron methyl [2-(4,6-bis(difluoromethoxy)-pyrimidin-2-ylcarbamoylsulfamoyl)benzoic acid], and rimsulfuron [1-(4,6-dimethoxypyrimidin-2-yl)-3-(3-ethylsulfonyl-2-pyridylsulfonyl)- urea] were investigated under laboratory conditions in a pH 6.5 sandy loam soil. In microbially active and sterile soil, the degradation of the three sulfonylureas followed first-order kinetics and was independent of the herbicide soil concentration up to 5 mg a.i. kg-1 of soil. In microbially active soil the mean half-lives of triasulfuron (26.2 d), primisulfuron methyl (30.2 d) and rimsulfuron (7.5 d) were, respectively, 4.0, 3.7, and 1.9 times lower than those in sterile soil, thus confirming the decisive contribution of biological processes in soil degradation of the three sulfonylureas. At the concentrations of 0.2 and 5 mg a.i. kg-1 of soil, no detrimental effects of the three sulfonylureas on soil respiration and dehydrogenase activity were detected. Indeed, soil amended with the three sulfonylureas at 5 mg a.i. kg-1 of soil showed a transient increase of both respiration and dehydrogenase activity. Results showed that triasulfuron, primisulfuron methyl, and rimsulfuron have probably no effects on soil microbial activities at the concentrations used in agricultural practice, which are approximately 1/10 of the lowest concentration tested in the present study
Losses of atrazine, metolachlor, prosulfuron and triasulfuron in subsurface drain water. I. Field results
No full textThe objective of this experiment was to estimate field-scale losses of metolachlor, prosulfuron, triasulfuron, atrazine and two of its metabolites (deethylatrazine and deisopropylatrazine) in subsurface drain water of two experimental sites located in the Po Valley (Italy), from April 1996 to March 1999. Atrazine and metolachlor concentrations in drain water of the two experimental sites showed similar patterns. However, different concentrations were observed. In the Cadriano silty loam, concentration peaks of 20.6 and 18.2 μg·L-1, respectively, for atrazine and metolachlor, were observed. In the Carpi silty clay, higher concentrations were observed (atrazine: 127.0 μg·L-1, metolachlor: 180.0 μg·L-1). The results obtained suggest an involvement of preferential flow in the overall transport of the four herbicides in the soil. Estimated losses of atrazine, metolachlor, prosulfuron and triasulfuron in subsurface drain water were respectively 0.27, 0.61, 2.3 and 0.73% of the applied rate in Cadriano, and 2.14, 1.14, 10.6 and 0.07% of the applied rate in Carpi
Atrazine and metolachlor degradation in subsoils
No full textDegradation of atrazine [2-chloro-4-etylamino-6-isopropylamino-1,3,5-triazine] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] in sterile and non-sterile soil samples collected at two different soil depths (0-20 and 80-110 cm) and incubated under aerobic and anaerobic conditions was studied. Under aerobic conditions, the half-life of atrazine in non-sterile surface soil was 49 days. In non-sterile subsoil, the half-life of atrazine (119 days) was increased by 2.5 times compared in surface soils and was not statistically different from half-lives in sterile soils (115 and 110 days in surface soil and subsoil, respectively). Metolachlor degradation occurred only in non-sterile surface soil, with a half-life of 37 days. Under anaerobic conditions, atrazine degradation was markedly slower than under aerobic conditions, with a half-life of 124 and 407 days in non-sterile surface soil and non-sterile subsoil, respectively. No significant difference was found in atrazine degradation in both sterile surface soil (693 days) and subsoil (770 days). Under anaerobic conditions, degradation of metolachlor was observed only in non-sterile surface soil. Results suggest that atrazine degraded both chemically and biologically, while metolachlor degraded only biologically. In addition, observed Eh values of soil samples incubated under anaerobic conditions suggest a significant involvement of soil microorganisms in the overall degradation process of atrazine under anaerobic conditions
Short-time effects of pure and formulated herbicides on soil microbial activity and biomass
No full textThe short-time of six pure herbicides (atrazine, terbuthylazine, rimsulfuron, primisulfuron-methyl, glyphosate and gluphosinate-ammonium) with respect to the corresponding commercial formulations on microbial activity and biomass of sandy loam soil were investigated. Application rates were: agricultural rate, 20 and 200 μg a.i. g-1 soil. Application at normal agricultural rates did not lead to significant effects on soil microbial activity, whereas soil microbial activity was markedly stimulated when pure and commercial formulations of the six herbicides were applied at 20 μg a.i. g-1 soil. The addition of 200 μg a.i. g-1 soil of four pure herbicides (atrazine, terbuthylazine, rimsulfuron, primisulfuron-methjyl) led to a significant decrease of soil microbial activity. Commercial formulations characterized by a higher relative a.i. concentration (atrazine and primisulfuron-methyl) approximately determined the same decreasing effect of the pure compound, whereas herbicide formulations with a lower relative a.i. concentration (terbuthylazine and rimsulfuron) produced a significant increase in soil microbial activity
covRew: A python toolkit for pre-processing pipeline rewriting ensuring coverage constraint satisfaction
No full textThis demo presents covRew, a Python toolkit for rewriting slicing operations in pre-processing pipelines (i.e., pipelines to be executed before further tasks, such as data analytics and machine learning) so that the pipeline execution ensures that protected groups are adequately represented (i.e., covered) in the result. The toolkit includes: (i) an analyzer, which identifies candidate operations for rewriting; (ii) a rewriter, which transforms operations for ensuring coverage satisfaction with respect to user specified constraints; (iii) an impact evaluator, allowing the user to assess the impact of the rewriting on the obtained results
Comparison of the persistence of atrazine and metolachlor under field and laboratory conditions
No full textA study was carried out in a loamy soil to evaluate the degradation of atrazine and metolachlor under laboratory-controlled and field-variable conditions as a function of temperature and soil moisture content. In laboratory trials, metolachlor showed fast degradation, with half-lives from 100 to 5.7 days in a temperature range from 5 to 35 °C at 100% of field capacity, whereas in the same conditions the degradation rate of atrazine was relatively slow, with half-lives from 407 to 23 days. Modeling of laboratory degradation data to predict field persistence was carried out. Field persistence of atrazine and metolachlor was measured in the same soil during the corn growing seasons in 1993, 1994, and 1996. In the three years the mean half-dissipation times for atrazine and metolachlor were 36 and 21 days, respectively. Calculations from model equations gave acceptable prediction of field dissipation of both herbicides. Limitations and perspectives of employed modelization procedure are discussed
friends in the data science era
No full textThe data science era is characterized by data-driven automated decision systems (ADS) enabling, through data analytics and machine learning, automated decisions in many contexts, deeply impacting our lives. As such, their downsides and potential risks are becoming more and more evident: technical solutions, alone, are not sufficient and an interdisciplinary approach is needed. Consequently, ADS should evolve into data-informed ADS, which take humans in the loop in all the data processing steps. Data-informed ADS should deal with data responsibly, guaranteeing nondiscrimination with respect to protected groups of individuals. Nondiscrimination can be characterized in terms of different types of properties, like fairness and diversity. While fairness, i.e., absence of bias against minorities, has been widely investigated in machine learning, only more recently this issue has been tackled by considering all the steps of data processing pipelines at the basis of ADS, from data acquisition to analysis. Additionally, fairness is just one point of view of nondiscrimination to be considered for guaranteeing equity: other issues, like diversity, are raising interest from the scientific community due to their relevance in society. This paper aims at critically surveying how nondiscrimination has been investigated in the context of complex data science pipelines at the basis of data-informed ADS, by focusing on the specific data processing tasks for which nondiscrimination solutions have been proposed
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