The efficacy and potential risks of controlling sprouting in Finnish birches (Betula spp.) with the fungal decomposer Chondrostereum purpureum

Sprouting of fast-growing broad-leaved trees causes problems in young coniferous stands, under power transmission lines and along roads and railways. Public opinion and the Finnish Forest Certification System oppose the use of chemical herbicides to control sprouting, which means that most areas with problems rely on mechanical cutting. However, cutting is a poor control method for many broad-leaved species because the removal of leaders can stimulate the sprouting of side branches and cut stumps quickly re-sprout. In order to be effective, cutting must be carried out frequently but each cut increases the costs, making this control method increasingly difficult and expensive once begun. As such, alternative methods for sprout control that are both effective and environmentally sound represent a continuing challenge to managers and research biologists. Using biological control agents to prevent sprouting has been given serious consideration recently. Dutch and Canadian researchers have demonstrated the potential of the white-rot fungus Chondrostereum purpureum (Pers. ex Fr.) Pouzar as a control agent of stump sprouting in many hardwoods. These findings have focused the attention of the Finnish forestry community on the utilization of C. purpureum for biocontrol purposes. Primarily, this study sought determines the efficacy of native C. purpureum as an inhibitor of birch stump sprouting in Finland and to clarify its mode of action. Additionally, genotypic variation in Finnish C. purpureum was examined and the environmental risks posed by a biocontrol program using this fungus were assessed. Experimental results of the study demonstrated that C. purpureum clearly affects the sprouting of birch: both the frequency of living stumps and the number of living sprouts per stump were effectively reduced by the treatment. However, the treatment had no effect on the maximum height of new sprouts. There were clear differences among fungal isolates in preventing sprouting and those that possessed high oxidative activities as measured in the laboratory inhibited sprouting most efficiently in the field. The most effective treatment time during the growing season was in early and mid summer (May July). Genetic diversity in Nordic and Baltic populations of C. purpureum was found to be high at the regional scale but locally homogeneous. This natural distribution of diversity means that using local genotypes in biocontrol programs would effectively prevent the introduction of novel genes or genotypes. While a biocontrol program using local strains of C. purpureum would be environmentally neutral, pruned birches that are close to the treatment site would have a high susceptibility to infect by the fungus during the early spring.

Strategic Information Acquisition: Applications to Herding and Auctions

The information that the economic agents have and regard relevant to their decision making is often assumed to be exogenous in economics. It is assumed that the agents either poses or can observe the payoff relevant information without having to exert any effort to acquire it. In this thesis we relax the assumption of ex-ante fixed information structure and study what happens to the equilibrium behavior when the agents must also decide what information to acquire and when to acquire it. This thesis addresses this question in the two essays on herding and two essays on auction theory. In the first two essays, that are joint work with Klaus Kultti, we study herding models where it is costly to acquire information on the actions that the preceding agents have taken. In our model the agents have to decide both the action that they take and additionally the information that they want to acquire by observing their predecessors. We characterize the equilibrium behavior when the decision to observe preceding agents' actions is endogenous and show how the equilibrium outcome may differ from the standard model, where all preceding agents actions are assumed to be observable. In the latter part of this thesis we study two dynamic auctions: the English and the Dutch auction. We consider a situation where bidder(s) are uninformed about their valuations for the object that is put up for sale and they may acquire this information for a small cost at any point during the auction. We study the case of independent private valuations. In the third essay of the thesis we characterize the equilibrium behavior in an English auction when there are informed and uninformed bidders. We show that the informed bidder may jump bid and signal to the uninformed that he has a high valuation, thus deterring the uninformed from acquiring information and staying in the auction. The uninformed optimally acquires information once the price has passed a particular threshold and the informed has not signalled that his valuation is high. In addition, we provide an example of an information structure where the informed bidder initially waits and then makes multiple jumps. In the fourth essay of this thesis we study the Dutch auction. We consider two cases where all bidders are all initially uninformed. In the first case the information acquisition cost is the same across all bidders and in the second also the cost of information acquisition is independently distributed and private information to the bidders. We characterize a mixed strategy equilibrium in the first and a pure strategy equilibrium in the second case. In addition we provide a conjecture of an equilibrium in an asymmetric situation where there is one informed and one uninformed bidder. We compare the revenues that the first price auction and the Dutch auction generate and we find that under some circumstances the Dutch auction outperforms the first price sealed bid auction. The usual first price sealed bid auction and the Dutch auction are strategically equivalent. However, this equivalence breaks down in case information is acquired during the auction.

HIV outbreak among injecting drug users in Finland

An HIV outbreak among Finnish injecting drug users (IDUs) occurred in 1998. By the end of 2005, 282 IDUs were in-fected, most of them by recombinant virus CRF01_AE of HIV. After a rapid spread, the outbreak subsided, and the prevalence of HIV among IDUs remained low (<2%). The purpose of the study was to describe the outbreak in order to recognise factors that have influenced the spread and restriction of the outbreak, and thus to find tools for HIV preven-tion. Data on Finnish IDUs newly diagnosed HIV-positive between 1998 and 2005 was collected through interviews and patient documents. Study I compared markers of disease progression between 93 Finnish IDUs and 63 Dutch IDUs. In study II, geographical spread of the HIV outbreak was examined and compared with the spatial distribution of employed males. In study III, risk behaviour data from interviews of 89 HIV-positive and 207 HIV-negative IDUs was linked, and prevalence and risk factors for unprotected sex were evaluated. In study IV, data on 238 newly diagnosed IDUs was combined with data on 675 sexually transmitted HIV cases, and risk factors for late HIV diagnosis (CD4 cell count <200/µL, or AIDS at HIV diagnosis) were analysed. Finnish IDUs infected with CRF01_AE exhibited higher viral loads than did Amsterdam IDUs infected with subtype B, but there was no difference in CD4 development. The Finnish IDU outbreak spread and was restricted socially in a marginalised IDU population and geographically in areas characterised by low proportions of employed males. Up to 40% of the cases in the two clusters outside the city centre had no contact with the centre, where needle exchange services were available since 1997. Up to 63% of HIV-positive and 80% of HIV-negative sexually active IDUs reported inconsistent condom use, which was associated with steady relationships and recent inpatient addiction care. Com-pared to other transmission groups, HIV-positive IDUs were diagnosed earlier in their infection. The proportion of late diagnosed HIV cases in all transmission groups was 23%, but was only 6% among IDUs diagnosed during the first four years of the epidemic. The high viral load in early HIV infection may have contributed to the rapid spread of recombinant virus in the Finnish outbreak. The outbreak was restricted to a marginalised IDU population, and limited spatially to local pockets of pov-erty. To prevent HIV among IDUs, these pockets should be recognised and reached early through outreach work and the distribution of needle exchange and other prevention activities. To prevent the sexual transmission of HIV among IDUs, prevention programmes should be combined with addiction care services and targeted at every IDU. The early detection of the outbreak and early implementation of needle exchange programmes likely played a crucial role in re-versing the IDU outbreak.

Modeling of Surface UV Radiation Using Satellite Data

Solar UV radiation is harmful for life on planet Earth, but fortunately the atmospheric oxygen and ozone absorb almost entirely the most energetic UVC radiation photons. However, part of the UVB radiation and much of the UVA radiation reaches the surface of the Earth, and affect human health, environment, materials and drive atmospheric and aquatic photochemical processes. In order to quantify these effects and processes there is a need for ground-based UV measurements and radiative transfer modeling to estimate the amounts of UV radiation reaching the biosphere. Satellite measurements with their near-global spatial coverage and long-term data conti-nuity offer an attractive option for estimation of the surface UV radiation. This work focuses on radiative transfer theory based methods used for estimation of the UV radiation reaching the surface of the Earth. The objectives of the thesis were to implement the surface UV algorithm originally developed at NASA Goddard Space Flight Center for estimation of the surface UV irradiance from the meas-urements of the Dutch-Finnish built Ozone Monitoring Instrument (OMI), to improve the original surface UV algorithm especially in relation with snow cover, to validate the OMI-derived daily surface UV doses against ground-based measurements, and to demonstrate how the satellite-derived surface UV data can be used to study the effects of the UV radiation. The thesis consists of seven original papers and a summary. The summary includes an introduction of the OMI instrument, a review of the methods used for modeling of the surface UV using satellite data as well as the con-clusions of the main results of the original papers. The first two papers describe the algorithm used for estimation of the surface UV amounts from the OMI measurements as well as the unique Very Fast Delivery processing system developed for processing of the OMI data received at the Sodankylä satellite data centre. The third and the fourth papers present algorithm improvements related to the surface UV albedo of the snow-covered land. Fifth paper presents the results of the comparison of the OMI-derived daily erythemal doses with those calculated from the ground-based measurement data. It gives an estimate of the expected accuracy of the OMI-derived sur-face UV doses for various atmospheric and other conditions, and discusses the causes of the differences between the satellite-derived and ground-based data. The last two papers demonstrate the use of the satellite-derived sur-face UV data. Sixth paper presents an assessment of the photochemical decomposition rates in aquatic environment. Seventh paper presents use of satellite-derived daily surface UV doses for planning of the outdoor material weathering tests.

Process of burnout: structure, antecedents, and consequences

The major changes that have been witnessed in today's workplaces are challenging the mental well-being of employed people. Stress and burnout are considered to be modern epidemics, and their importance to physical health and work ability has been acknowledged world-wide. The aim of the thesis was to study the concept of burnout as a process proceeding from its antecedents, through the development of the syndrome, and to its outcomes. Several work-related factors considered antecedents of burnout were studied in different occupational groups. The syndrome of burnout is seen as consisting of three dimensions - exhaustion, cynicism and lack of professional efficacy - and different alternatives for the sequential development of these dimensions were tested. Furthermore, several indicators of the severely detrimental health and work ability outcomes of burnout were investigated in a longitudinal study design. The research questions were as follows. 1) Is burnout, as measured with the Maslach Burnout Inventory - General Survey (MBI-GS), a three-dimensional construct and how invariant is the factorial structure across occupations (Finnish) and national samples (Finnish, Swedish and Dutch)? How persistent is exhaustion over time? 2) What is the sequential process of burnout? Is it similar across occupations? How do work stressors relate to the process? 3) How does burnout relate to severe health consequences as well as temporary and chronic work disability according to hospitalization periods, sick-leave episodes and receiving disability pensions? The data were collected between 1986 and 2005. The population of the study consisted of respondents to a company-wide questionnaire survey carried out in 1996-1997 (N=9705, response rate 63%). The participants comprised 6025 blue-collar workers and 3680 white-collar workers. The majority were men (N=7494) and the average age was 43.7 years. In addition, a sample from the population had responded to a questionnaire survey in 1988, which was combined with the 1996 data to form panel data on 713 respondents. The register-based data were collected between 1986 and 2005 from 1) the company's occupational health services' records for a sample of respondents from the 1996 questionnaire survey (sick-leave data), 2) hospitalization records from the Hospital discharge register, and 3) disability pension records from the Finnish Centre for Pensions. These data were combined person by person with the 1996 questionnaire survey data with the help of personal identification numbers which were saved with the study numbers by the researchers. The results showed that burnout consists of three separate but correlating symptoms: exhaustion, cynicism and lack of professional efficacy. As a syndrome, burnout was strongly related to job stressors at work, and seemed to develop from exhaustion through cynicism to lack of professional efficacy in a similar manner among white-collar and blue-collar employees. The results also showed that exhaustion persisted even after eight years of follow-up but did not predict cynicism or lack of professional efficacy after that amount of time. Nor were job stressors longitudinally related to burnout. Longitudinal results were obtained for the severe health-related consequences of burnout. The investigated outcomes represented different phases of health deterioration ranging from sick-leaves and hospitalization periods to receiving work disability pensions. The results showed that burnout syndrome, and its elements of exhaustion and cynicism, were related to future mental and cardiovascular disorders as indicated by hospitalization periods. Burnout was also related to future sick-leave periods due to mental, cardiovascular and musculoskeletal disorders. Of the separate elements, exhaustion was related to the same three categories of disorder, cynicism to mental, musculoskeletal and digestive disorders, and lack of professional efficacy to mental and musculoskeletal disorders. Burnout also predicted receiving disability pensions due to mental and musculoskeletal disorders among initially healthy subjects. Exhaustion was related to receiving disability pensions even when self-reported chronic illness was taken into account. The results suggest that burnout is a multidimensional, chronic, work-related syndrome, which may have serious consequences for health and work ability.