Chlorpyrifos (CPF) is a popular organophosphorus insecticide that is heavily used in the agriculture industry as a means of pest control. Chlorpyrifos is known for its toxic effect to inhibit the enzyme acetylcholinesterase (ACHE) in humans and is widely used in areas of California where the site of application is close to occupied areas, such that exposures to residents and bystanders can occur due to secondary drift. Secondary drift refers to the volatilization of a pesticide from the surface to which it was applied (e.g. soil or plant foliage) and subsequent off-site movement in ambient air. Secondary drift is different from spray drift, which occurs during and very shortly after application. The goal of this thesis is to evaluate existing measurements of secondary drift from ambient air measurements of CPF available from California’s Air Monitoring Network (AMN), in comparison to predictions using a state-of-the-art dispersion model. Pesticide use data were obtained from the California Department of Pesticide Regulation (CDPR) website and was compiled to form scenarios to be modeled and compared against measurements taken throughout the year. Probability distributions for the measured and predicted CPF concentrations resulted in correlations ranging from 3% to 91% depending on the year and modeled scenario. Overall the model overpredicted air concentrations for the modeled scenarios, providing conservative values for risk assessment purposes.

Agrichemical spray drift is an issue of concern for the orcharding industry. Shelterbelts surrounding orchard blocks can significantly reduce spray drift by intercepting droplets from the airflow. At present, there is little information available with which to predict drift deposits downwind, particularly in the case of a fully-sheltered orchard block. In this thesis, we develop a simple mathematical model for the transport of airborne drifting spray droplets, including the effects of droplet evaporation and interception by a shelterbelt. The object is for the model to capture the major features of the droplet transport, yet be simple enough to determine an analytic solution, so that the deposit on the ground may be easily calculated and the effect of parameter variations observed. We model the droplet transport using an advection-dispersion equation, with a trapping term added to represent the shelterbelt. In order to proceed analytically, we discretise the shelterbelt by dividing it into a three-dimensional array of blocks, with the trapping in each block concentrated to the point at its centre. First, we consider the more straightforward case where the droplets do not evaporate; solutions are presented in one, two and three dimensions, along with explicit expressions for the total amount trapped and the deposit on the ground. With evaporation, the model is more difficult to solve analytically, and the solutions obtained are nestled in integral equations which are evaluated numerically. In both cases, examples are presented to show the deposition profile on the ground downwind of the shelterbelt, and the corresponding reduction in deposit from the same scenario without the shelterbelt.

<p>This thesis is a part of a project where a new method, the base descriptor approach, is studied. The purpose of this method is to reduce drift and extract vital information from electronic tongue measurements. Reference solutions, called descriptors, are measured and the measurements are used to find base descriptors. A base descriptor is, in this thesis, a regression vector for prediction of the property that the descriptor represent. The property is in this case the concentration of a chemical substance in the descriptor solution. Measurements from test samples, in this case fruit juices, are projected onto the base descriptors to extract vital and drift-stable information from the test samples. </p><p>The base descriptors are used to determine the concentrations of the descriptors'chemical substances in the juices and thereby also to classify the different juices. It is assumed that the measurements of samples of juices and descriptors drift the same way. This assumption has to be true in order for the base descriptor approach to work. The base descriptors are calculated by multivariate regression methods like partial least squares regression (PLSR) and principal component regression (PCR). </p><p>Only two of the descriptors tested in this thesis worked as basis for base descriptors. The base descriptors'predictions of the concentrations of chemical substances in the juices are hard to evaluate since the true concentrations are unknown. Comparing the projections of juice measurements onto the base descriptors with a classification model on the juice measurements performed by principal component analysis (PCA), there is no significant difference in drift of the juice measurements in the results of the two methods. The base descriptors, however, separates the juices for classification somewhat better than the classification of juices performed by PCA.</p>

<p>The effect of water temperature prey capture success and foraging behavior of drift-feeding juvenile brown trout (<em>Salmo trutta</em>) was examined in a laboratory stream. Water temperature treatments were 5.7, 6.7, 8.0, 10, 12 and 14°C. Five wild brown trout, age 1+ and collected by electrofishing from a stream in Western Sweden, were used in the experiments. There was a significant effect of water temperature on both prey capture probability and the percentage of time spent resting on the substrate while drift-feeding. At low water temperatures the fish suffered a reduced prey capture capability and spent more time resting on the substrate in between the excursions to capture drifting prey. Temperature did not significantly affect the amount of time fish spent foraging holding a station in the current versus active searching. Significant positive correlations were found between holding a station and prey capture probability at four out of the six different water temperature treatments.</p><p> </p>

Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2008.

Background: Studying insider trading is difficult due to its sensitive and delicate nature. Therefore it is hard to gauge the extent of such activities. This problem has resulted in a fierce debate whether it should be prohibited or not. Using a method where the effect on monopolistic information usage can be isolated insider trading can be monitored. Such an event is a profit warning. Purpose: This paper examines whether insider trading exist for companies making a profit warning between year 2003 and 2007 on the Stockholm Stock Exchange. Furthermore the aim with the study is to contribute to the debate on the insider trading legislation. Method: The study’s purpose is achieved through an event study studying the cumulative abnormal return as well as average daily returns during the thirty days preceding the warning for a sample of thirty companies. Since profit warnings should be completely random and as such almost impossible for the market to know in advance, a significant abnormal return can only be explained with insider trading. The abnormal returns were calculated using the Capital Asset Pricing Model since it is the most widely used model. Conclusion: For the chosen time frame, when testing on a 95% significance level, the study found a significant abnormal return during the last 10 days of the event window but not for the entire period of thirty days. The daily average return for the thirty companies were significant for six of the thirty days within the event window. Two of them were included in the last ten day period with a confirmed significant abnormal return which might suggest that on average insider trading tend to occur during these days. The other four was discarded due to sample issues. Since the study was limited to a period of four years extending the results to a period other than tested should be made with great care since conditions may differ over time. Concerning the current debate on the insider legislation, the findings can be used by both sides. Either to argue for a strengthening of the law or to question its existence.

Background: Studying insider trading is difficult due to its sensitive and delicate nature. Therefore it is hard to gauge the extent of such activities. This problem has resulted in a fierce debate whether it should be prohibited or not. Using a method where the effect on monopolistic information usage can be isolated insider trading can be monitored. Such an event is a profit warning. Purpose: This paper examines whether insider trading exist for companies making a profit warning between year 2003 and 2007 on the Stockholm Stock Exchange. Furthermore the aim with the study is to contribute to the debate on the insider trading legislation. Method: The study’s purpose is achieved through an event study studying the cumulative abnormal return as well as average daily returns during the thirty days preceding the warning for a sample of thirty companies. Since profit warnings should be completely random and as such almost impossible for the market to know in advance, a significant abnormal return can only be explained with insider trading. The abnormal returns were calculated using the Capital Asset Pricing Model since it is the most widely used model. Conclusion: For the chosen time frame, when testing on a 95% significance level, the study found a significant abnormal return during the last 10 days of the event window but not for the entire period of thirty days. The daily average return for the thirty companies were significant for six of the thirty days within the event window. Two of them were included in the last ten day period with a confirmed significant abnormal return which might suggest that on average insider trading tend to occur during these days. The other four was discarded due to sample issues. Since the study was limited to a period of four years extending the results to a period other than tested should be made with great care since conditions may differ over time. Concerning the current debate on the insider legislation, the findings can be used by both sides. Either to argue for a strengthening of the law or to question its existence.

För att erhålla en rättvisande redovisning måste utgångspunkten vara att ett företag skall fortleva. I en revisors uppgifter ingår att granska huruvida ett företag kan tillämpa principen om fortsatt drift enligt RS 570. Eftersom denna princip är väsentlig för redovisningens struktur medför detta vissa krav på att revisorn gör en korrekt bedömning av företagets fortlevnad. Att yttra sig om den fortsatta driften kan emellertid få svåra konsekvenser för företaget eftersom intressenterna baserar sina beslut på det som står i årsredovisningen och revisionsberättelsen. Vissa författare menar till och med att ett negativt yttrande om den fortsatta driften kan leda till en självuppfyllande profetia. Vi har således funnit det intressant att utreda huruvida revisorerna upplever några svårigheter i samband med bedömningen av ett företags fortsatta drift. Vidare ämnar vi ta reda på hur vanligt det är att revisorer anmärker på den fortsatta driften samt huruvida mer praxis och vägledning behövs i RS 570. Syftet med uppsatsen är att skapa en diskussion och en förståelse för de problem som kan omgärda bedömningen av fortsatt drift. Vår studie har föregåtts av både ett kvantitativt och ett kvalitativt angreppssätt, då vi utförde dels en webbenkät och dels personliga semi-strukturerade intervjuer. Efter genomförd empiri visar studien att de flesta revisorer som ingått i våra undersökningar upplever svårigheter vid bedömningen av fortsatt drift. Anledning till detta är att bedömningen involverar förutsägelser om framtiden samt att risken finns för att bedömningen i sig blir självuppfyllande. Vidare har vi konstaterat att åsikterna går isär huruvida mer praxis kring RS 570 är nödvändigt. De flesta anser emellertid att RS 570 innehåller tillräcklig vägledning vid bedömningen av fortsatt drift. Slutligen har vi kommit fram till att det är relativt ovanligt att revisorerna i vår undersökning anmärker på den fortsatta driften i revisionsberättelsen, troligen på grund av de svårigheter som omgärdar bedömningen.

This paper examines whether the phenomena of price drift around quarterly earnings re-leases exist among firms listed on the large cap. list at the Stockholm Stock Exchange for a time period ranging from the first quarter of 2003 to the second quarter of 2006. It fur-thermore examines the ability of the variables forecast error, relative to analyst’s estimates, and firms’ size to explain the variation in price drift among firms. A sample of some 30 firms were drawn in the first three quarters of each year between 2003 and 2005, for the year of 2006 only the fist two quarters were included in the study. For each quarter all firms were classified into three different portfolios on the basis of earnings deviations relative to mean analyst’s estimates (forecast error). The returns for each firm in all portfolios were investigated during 20 days post- and pre quarterly earnings release date, resulting in an event window totaling 41 days. In order to clear out effects from general market movements the Capital Asset Pricing Model, CAPM, was used in which betas were estimated for all firms each quarter. The findings from this study indicate that price drift, measured by cumulative abnormal re-turn, occur for firms with both negative forecast error as well as positive. For firms with positive error, statistically significant positive price drift was found for both the pre- and post period. As for the firms with earnings below analyst’s mean estimates, negative prean-nouncement drift was statistically supported. The ability of firms size and forecast error to explain the variation in price drift on a stock level was very weak, R2 measures of below 5% was reported. However, forecast error was a strongly significant independent variable in the context of the regressions run for both pre- and post-announcement drift. The firms below the lower market cap. quartile in the sample show, on average, lower pre-announcement drift than the firms belonging in the largest quartile. Concerning market efficiency among the large cap. firms the price drift found is an indica-tion of market inefficiency both it terms of the semi strong and the strong form. However, care should be taken before generalizing the results from this study but. Possible misspeci-fication of the equilibrium return model will skew the price drift measurement. Moreover, speculation is not explicitly controlled for in this test. Finally, this study is done within a li-mited time span; hence generalization over time is not possible

Post earnings announcement drift (PEAD) is defined as the drift that occurs in a company’s share priceafter their earnings announcement. A company that reports earnings above (below) the analysts’expectations should, according to previous studies of PEAD, continue to drift upwards (downwards)after the announcement. (Ball &amp; Brown, 1968) The thesis purpose is to investigate if PEAD existed onthe Swedish market between 2006-2010. We test PEAD’s existences through; (i) creating portfolios inwhich companies’ abnormal return (AR) we expect to decline or increase, (ii) doing a multiple regressionanalysis to test if the drift is statistically significant. From the results of our study, we can neither acceptnor reject the hypothesis that PEAD existed on the Swedish market, although the multiple regressionanalysis prove a statistically significant result for companies’ AR that we expect to decline have drifted3,11% in a negative direction compared to our total sample.