Sediment resuspension as a water quality regulator in lakes

Sediment resuspension, the return of the bottom material into the water column, is an important process that can have various effects on a lake ecosystem. Resuspension caused by wind-induced wave disturbance, currents, turbulent fluctuations and bioturbation affects water quality characteristics such as turbidity, light conditions, and concentrations of suspended solids (SS) and nutrients. Resuspension-mediated increase in turbidity may favour the dominance of phytoplankton over macrophytes. The predator-prey interactions contributing to the trophic state of a lake may also be influenced by increasing turbidity. Directly, the trophic state of a lake can be influenced by the effect of sediment resuspension on nutrient cycling. Resuspension enhances especially the cycling of phosphorus by bringing the sedimentary nutrients back into the water column and may thereby induce switches between phosphorus and nitrogen limitation. The contribution of sediment resuspension to gross sedimentation, turbidity, and concentration of SS and nutrients was studied in a small, deep lake as well as in a multibasin lake with deep and shallow areas. The effect of ice cover on sediment resuspension and thereby on phosphorus concentrations was also studied. The rates of gross sedimentation and resuspen¬sion were estimated with sediment traps and the associations between SS and nutrients were considered. Sediment resuspension, caused by wind activity, comprised most of the gross sedimenta¬tion and strongly contributed to the concentration of SS and turbidity in the lakes studied. Additionally, via the influence on SS, resuspension affected the concentration of total phosphorus (TP) and soluble reactive phosphorus (SRP), as well as the total nitrogen to total phosphorus (TN:TP) ratio. Although contrasting results concerning the dependence between the SS and SRP concentrations were observed, it could be concluded that sediment resuspension during strong algal blooms (pH > 9) led to aerobic release of P. The main findings of this thesis were that in the course of the growing season, sediment resuspension coupled with phytoplankton succession led to liberation of P from resuspended particles, which in turn resulted in high TP concentrations and low TN:TP ratios. This development was likely a cause of strong cyanobacterial blooms in midsummer.

Depression and Cognition in Type 2 Diabetes from a Life Course Perspective

Background: Type 2 diabetes is linked to several complications which add to both physical and mental distress. Depression is a common co-morbidity of diabetes which can occur both as a cause and a consequence of type 2 diabetes. Depression has been shown to correlate with glucose regulation and treating depression might prove beneficial for glucose regulation as well as for mental well being. Another complication which might affect diabetes management is cognitive decline. Several risk factors and complications of diabetes might modify the risk for developing cognitive impairment, which is increased 1.5 times among subjects with type 2 diabetes. Type 2 diabetes, depression and impaired cognitive performance have all been linked to low birth weight. This thesis aimed to explore the effects and interactions of birth weight, depression and cognitive ability in relation to type 2 diabetes from a life course perspective. Subjects and methods: Studies I, II and V were part of the Helsinki Birth Cohort Study. 2003 subjects participated in an extensive clinical examination at an average age of 61 years. A standard glucose tolerance test (OGTT) was performed and depressive symptoms were assessed using the Beck Depression Inventory (BDI). In addition data was obtained from child welfare clinics and national registers. A subset of the cohort (n=1247) also performed a test on cognitive performance (CogState ®) at the average age of 64. Studies III and IV were randomised clinical trials where mildly depressed diabetic subjects were treated with paroxetine or placebo and the effect on metabolic parameters and quality of life was assessed. The first trial included 14 women and lasted 10 weeks, while the second trial included 43 subjects, both men and women, and lasted 6 months. Results: Type 2 diabetes was positively associated with the occurrence of depressive symptoms. Among diabetic subjects 23.6% had depressive symptoms, compared to 16.7% of subjects with normal glucose tolerance (OR = 1.77, p<0.001). Formal mediation analysis revealed that cardiovascular disease (CVD) is likely to act as a mediator in the association. Furthermore, low birth weight was found to modify the association between type 2 diabetes, CVD and depression. The association between BDI score and having type 2 diabetes or CVD was twice as strong in the subgroup with low birth weight (≤ 2500g) compared with the group with birth weight > 2500g (p for interaction 0.058). In the six months long randomised clinical trial (study IV) paroxetine had a transient beneficial effect on glycosylated haemoglobin A1c (GHbA1c) and quality of life when compared to placebo after three months of treatment. In study V we found that subjects with known diabetes had a consistently poorer level of cognitive performance than subjects with normal glucose tolerance in most of the tested cognitive domains. This effect was further amplified among those born with a small birth weight (p for interaction 0.002). Conclusions: Type 2 diabetes is associated with a higher occurrence of depressive symptoms compared to subjects with normal glucose tolerance. This association is especially strong among subjects with CVD and those born with a low birth weight. Treating depressed diabetic subjects with paroxetine has no long term effect on glucose regulation. Physicians should be aware of depression as an important co-morbidity of type 2 diabetes. Both depression and the cognitive decline often seen among diabetic subjects are increased if the subject is born with a low birth weight. Physicians should recognise low birth weight as an additional risk factor and modifier of diabetic complications.

Given and News : Media discourse and the construction of community on national days

National anniversaries such as independence days demand precise coordination in order to make citizens change their routines to forego work and spend the day at rest or at festivities that provide social focus and spectacle. The complex social construction of national days is taken for granted and operates as a given in the news media, which are the main agents responsible for coordinating these planned disruptions of normal routines. This study examines the language used in the news to construct the rather unnatural idea of national days and to align people in observing them. The data for the study consist of news stories about the Fourth of July in the New York Times, sampled over 150 years and are supplemented by material from other sources and other countries. The study is multidimensional, applying concepts from pragmatics (speech acts, politeness, information structure), systemic functional linguistics (the interpersonal metafunction and the Appraisal framework) and cognitive linguistics (frames, metaphor) as well as journalism and communications to arrive at an interdisciplinary understanding of how resources for meaning are used by writers and readers of the news stories. The analysis shows that on national anniversaries, nations tend to be metaphorized as persons having birthdays, to whom politeness should be shown. The face of the nation is to be respected in the sense of identifying the nation's interests as one's own (positive face) and speaking of citizen responsibilities rather than rights (negative face). Resources are available for both positive and negative evaluations of events and participants and the newspaper deftly changes footings (Goffman 1981) to demonstrate the required politeness while also heteroglossically allowing for a certain amount of disattention and even protest - within limits, for state holidays are almost never construed as Bakhtinian festivals, as they tend to reaffirm the hierarchy rather than invert it. Celebrations are evaluated mainly for impressiveness, and for the essentially contested quality of appropriateness, which covers norms of predictability, size, audience response, aesthetics, and explicit reference to the past. Events may also be negatively evaluated as dull ("banal") or inauthentic ("hoopla"). Audiences are evaluated chiefly in terms of their enthusiasm, or production of appropriate displays for emotional response, for national days are supposed to be occasions of flooding-out of nationalistic feeling. By making these evaluations, the newspaper reinforces its powerful position as an independent critic, while at the same time playing an active role in the construction and reproduction of emotional order embodied in "the nation's birthday." As an occasion for mobilization and demonstrations of power, national days may be seen to stand to war in the relation of play to fighting (Bateson 1955). Evidence from the newspaper's coverage of recent conflicts is adduced to support this analysis. In the course of the investigation, methods are developed for analyzing large collections of newspaper content, particularly topical soft news and feature materials that have hitherto been considered less influential and worthy of study than so-called hard news. In his work on evaluation in newspaper stories, White (1998) proposed that the classic hard news story is focused on an event that threatens the social order, but news of holidays and celebrations in general does not fit this pattern, in fact its central event is a reproduction of the social order. Thus in the system of news values (Galtung and Ruge 1965), national holiday news draws on "ground" news values such as continuity and predictability rather than "figure" news values such as negativity and surprise. It is argued that this ground helps form a necessary space for hard news to be seen as important, similar to the way in which the information structure of language is seen to rely on the regular alternation of given and new information (Chafe 1994).

Teknillisen korkeakoulun konetekniikan osaston opettajien ja opiskelijoiden kokemukset oppimisen arvioinnista ja palautteesta

Objectives. The purpose of this study was to examine perceptions of evaluation of learning and feedback among teachers and students of mechanical engineering at the Helsinki University of Technology. The differences and similarities between the perceptions of these two groups were also studied. Course feedback was examined, and a target was set to rationalize the collation and exploitation of the feedback data. The theoretical background for the evaluation of learning was based primarily on the theories of Brown (1997), Karjalainen (2001) and Rowntree (1977, 1988). The Biggs (2003) model on aligned teaching was used as an example of quality university education. Feedback practices were examined through the theory of Ramsden (1992) and many recent research articles. Methods. The qualitative study was executed by examining the evaluation of learning and feedback prac-tices of the courses in mechanical engineering at the Helsinki University of Technology. The data was gathered by interviewing the teachers responsible of basic and postgraduate studies, as well as students taking their basic studies. Four group interviews were arranged for both teachers and students, each with three participants. The data from these themed interviews were analyzed by means of content analysis. Result and conclusions. This study showed that teachers and students have similar perceptions of evalua-tion of learning and feedback excluding a few significant differences. The most essential difference in evaluation of learning was that students perceived the evaluation of the examinations to be inaccurate. Teachers on the other hand thought that the existing practice for the exam evaluation is working fine. Stu-dents also felt that they are not giving enough information on the opportunities to get feedback. Teachers instead expected students to actively ask for feedback. Students perceived the need for exploiting the course feedback for course development purposes more than before. Teachers saw foremost the challenges and problems in the exploitation of the feedback. In the future, more effort must be put on the research of the evaluation of learning and feedback, as the quality assurance and continuous improvement of the teaching calls for new data.

Routine Measurement of Health-Related Quality of Life in Assessing Cost-Effectiveness in Secondary Health Care

Aims: The aims of this study were 1) to identify and describe health economic studies that have used quality-adjusted life years (QALYs) based on actual measurements of patients' health-related quality of life (HRQoL); 2) to test the feasibility of routine collection of health-related quality of life (HRQoL) data as an indicator of effectiveness of secondary health care; and 3) to establish and compare the cost-utility of three large-volume surgical procedures in a real-world setting in the Helsinki University Central Hospital, a large referral hospital providing secondary and tertiary health-care services for a population of approximately 1.4 million. Patients and methods: So as to identify studies that have used QALYs as an outcome measure, a systematic search of the literature was performed using the Medline, Embase, CINAHL, SCI and Cochrane Library electronic databases. Initial screening of the identified articles involved two reviewers independently reading the abstracts; the full-text articles were also evaluated independently by two reviewers, with a third reviewer used in cases where the two reviewers could not agree a consensus on which articles should be included. The feasibility of routinely evaluating the cost-effectiveness of secondary health care was tested by setting up a system for collecting HRQoL data on approximately 4 900 patients' HRQoL before and after operative treatments performed in the hospital. The HRQoL data used as an indicator of treatment effectiveness was combined with diagnostic and financial indicators routinely collected in the hospital. To compare the cost-effectiveness of three surgical interventions, 712 patients admitted for routine operative treatment completed the 15D HRQoL questionnaire before and also 3-12 months after the operation. QALYs were calculated using the obtained utility data and expected remaining life years of the patients. Direct hospital costs were obtained from the clinical patient administration database of the hospital and a cost-utility analysis was performed from the perspective of the provider of secondary health care services. Main results: The systematic review (Study I) showed that although QALYs gained are considered an important measure of the effectiveness of health care, the number of studies in which QALYs are based on actual measurements of patients' HRQoL is still fairly limited. Of the reviewed full-text articles, only 70 reported QALYs based on actual before after measurements using a valid HRQoL instrument. Collection of simple cost-effectiveness data in secondary health care is feasible and could easily be expanded and performed on a routine basis (Study II). It allows meaningful comparisons between various treatments and provides a means for allocating limited health care resources. The cost per QALY gained was 2 770 for cervical operations and 1 740 for lumbar operations. In cases where surgery was delayed the cost per QALY was doubled (Study III). The cost per QALY ranges between subgroups in cataract surgery (Study IV). The cost per QALY gained was 5 130 for patients having both eyes operated on and 8 210 for patients with only one eye operated on during the 6-month follow-up. In patients whose first eye had been operated on previous to the study period, the mean HRQoL deteriorated after surgery, thus precluding the establishment of the cost per QALY. In arthroplasty patients (Study V) the mean cost per QALY gained in a one-year period was 6 710 for primary hip replacement, 52 270 for revision hip replacement, and 14 000 for primary knee replacement. Conclusions: Although the importance of cost-utility analyses has during recent years been stressed, there are only a limited number of studies in which the evaluation is based on patients own assessment of the treatment effectiveness. Most of the cost-effectiveness and cost-utility analyses are based on modeling that employs expert opinion regarding the outcome of treatment, not on patient-derived assessments. Routine collection of effectiveness information from patients entering treatment in secondary health care turned out to be easy enough and did not, for instance, require additional personnel on the wards in which the study was executed. The mean patient response rate was more than 70 %, suggesting that patients were happy to participate and appreciated the fact that the hospital showed an interest in their well-being even after the actual treatment episode had ended. Spinal surgery leads to a statistically significant and clinically important improvement in HRQoL. The cost per QALY gained was reasonable, at less than half of that observed for instance for hip replacement surgery. However, prolonged waiting for an operation approximately doubled the cost per QALY gained from the surgical intervention. The mean utility gain following routine cataract surgery in a real world setting was relatively small and confined mostly to patients who had had both eyes operated on. The cost of cataract surgery per QALY gained was higher than previously reported and was associated with considerable degree of uncertainty. Hip and knee replacement both improve HRQoL. The cost per QALY gained from knee replacement is two-fold compared to hip replacement. Cost-utility results from the three studied specialties showed that there is great variation in the cost-utility of surgical interventions performed in a real-world setting even when only common, widely accepted interventions are considered. However, the cost per QALY of all the studied interventions, except for revision hip arthroplasty, was well below 50 000, this figure being sometimes cited in the literature as a threshold level for the cost-effectiveness of an intervention. Based on the present study it may be concluded that routine evaluation of the cost-utility of secondary health care is feasible and produces information essential for a rational and balanced allocation of scarce health care resources.

Genetic Basis of Pituitary Adenoma Predisposition

Much of the global cancer research is focused on the most prevalent tumors; yet, less common tumor types warrant investigation, since A rare disorder is not necessarily an unimportant one . The present work discusses a rare tumor type, the benign adenomas of the pituitary gland, and presents the advances which, during the course of this thesis work, contributed to the elucidation of a fraction of their genetic background. Pituitary adenomas are benign neoplasms of the anterior pituitary lobe, accounting for approximately 15% of all intracranial tumors. Pituitary adenoma cells hypersecrete the hormones normally produced by the anterior pituitary tissue, such as growth hormone (GH) and prolactin (PRL). Despite their non-metastasizing nature, these adenomas can cause significant morbidity and have to be adequately treated; otherwise, they can compromise the patient s quality of life, due to conditions provoked by hormonal hypersecretion, such as acromegaly in the case of GH-secreting adenomas, or due to compressive effects to surrounding tissues. The vast majority of pituitary adenomas arise sporadically, whereas a small subset occur as component of familial endocrine-related tumor syndromes, such as Multiple Endocrine Neoplasia type 1 (MEN1) and Carney complex (CNC). MEN1 is caused by germline mutations in the MEN1 tumor suppressor gene (11q13), whereas the majority of CNC cases carry germline mutations in the PRKAR1A gene (17q24). Pituitary adenomas are also encountered in familial settings outside the context of MEN1 and CNC, but unlike in the latter syndromes, their genetic background until recently remained elusive. Evidence in previous literature supported the notion that a tumor suppressor gene on 11q13, residing very close to but still distinct from MEN1, causes genetic susceptibility to pituitary tumors. The aim of the study was to identify the genetic cause of a low penetrance form of Pituitary Adenoma Predisposition (PAP) in families from Northern Finland. The present work describes the methodological approach that led to the identification of aryl hydrocarbon receptor interacting protein (AIP) as the gene causing PAP. Combining chip-based technologies (SNP and gene expression arrays) with traditional gene mapping methods and genealogy data, we showed that germline AIP mutations cause PAP in familial and sporadic settings. PAP patients were diagnosed with mostly adenomas of the GH/PRL-secreting cell lineage. In Finland, two AIP mutations accounted for 16% of all patients diagnosed with GH-secreting adenomas, and for 40% of patients being younger than 35 years of age at diagnosis. AIP is suggested to act as a tumor suppressor gene, a notion supported by the nature of the identified mutations (most are truncating) and the biallelic inactivation of AIP in the tumors studied. AIP has been best characterized as a cytoplasmic interaction partner of aryl hydrocarbon receptor (AHR), also known as dioxin receptor, but it has other partners as well. The mechanisms that underlie AIP-mediated pituitary tumorigenesis are to date largely unknown and warrant further investigation. Because AIP was identified in the genetically homogeneous Finnish population, it was relevant to examine its contribution to PAP in other, more heterogeneous, populations. Analysis of pituitary adenoma patient series of various ethnic origins and differing clinical settings revealed germline AIP mutations in all cohorts studied, albeit with low frequencies (range 0.8-7.4%). Overall, PAP patients were typically diagnosed at a young age (range 8-41 years), mainly with GH-secreting adenomas, without strong family history of endocrine disease. Because many PAP patients did not display family history of pituitary adenomas, detection of the condition appeared challenging. AIP immunohistochemistry was tested as a molecular pre-screening tool on mutation-positive versus mutation-negative tumors, and proved to be a potentially useful predictor of PAP. Mutation screening of a large cohort of colorectal, breast, and prostate tumors did not reveal somatic AIP mutations. These tumors, apart from being the most prevalent among men and women worldwide, have been associated with acromegaly, particularly colorectal neoplasia. In this material, AIP did not appear to contribute to the pathogenesis of these common tumor types and other genes seem likely to play a role in such tumorigenesis. Finally, the contribution of AIP in pediatric onset pituitary adenomas was examined in a unique population-based cohort of sporadic pituitary adenoma patients from Italy. Germline AIP mutations may account for a subset of pediatric onset GH-secreting adenomas (in this study one of seven GH-secreting adenoma cases or 14.3%), and appear to be enriched among young (≤25 years old) patients. In summary, this work reveals a novel tumor susceptibility gene, namely AIP, which causes genetic predisposition to pituitary adenomas, in particular GH-secreting adenomas. Moreover, it provides molecular tools for identification of individuals predisposed for PAP. Further elaborate studies addressing the functional role of AIP in normal and tumor cells will hopefully expand our knowledge on endocrine neoplasia and reveal novel cellular mechanisms of pituitary tumorigenesis, including potential drug targets.

Quality Assessment of a Forest Inventory Based on Airborne Laser Scanning

In this study, a quality assessment method based on sampling of primary laser inventory units (microsegments) was analysed. The accuracy of a laser inventory carried out in Kuhmo was analysed as a case study. Field sample plots were measured on the sampled microsegments in the Kuhmo inventory area. Two main questions were considered. Did the ALS based inventory meet the accuracy requirements set for the provider and how should a reliable, cost-efficient and independent quality assessment be undertaken. The agreement between control measurement and ALS based inventory was analysed in four ways: 1) The root mean squared errors (RMSEs) and bias were calculated. 2) Scatter plots with 95% confidence intervals were plotted and the placing of identity lines was checked. 3) Bland-Altman plots were drawn so that the mean difference of attributes between the control method and ALS-method was calculated and plotted against average value of attributes. 4) The tolerance limits were defined and combined with Bland-Altman plots. The RMSE values were compared to a reference study from which the accuracy requirements had been set to the service provider. The accuracy requirements in Kuhmo were achieved, however comparison of RMSE values proved to be difficult. Field control measurements are costly and time-consuming, but they are considered to be robust. However, control measurements might include errors, which are difficult to take into account. Using the Bland-Altman plots none of the compared methods are considered to be completely exact, so this offers a fair way to interpret results of assessment. The tolerance limits to be set on order combined with Bland-Altman plots were suggested to be taken in practise. In addition, bias should be calculated for total area. Some other approaches for quality control were briefly examined. No method was found to fulfil all the required demands of statistical reliability, cost-efficiency, time efficiency, simplicity and speed of implementation. Some benefits and shortcomings of the studied methods were discussed.

Selenium and its effects on growth, yield and tuber quality in potato

Selenium (Se) has been demonstrated to be an essential trace element for maintenance of animal and human health. Although it has not been confirmed to be an essential micronutrient in higher plants, there is increasing evidence that Se functions as an antioxidant in plants. Selenium has been shown to exert a beneficial effect on crop growth and promotes stress tolerance at low concentrations. However, the specific physiological mechanisms that underlie the positive effects of Se in plants have not been clearly elucidated. The aims of this study were to determine the Se concentration in potato (Solanum tuberosum L.) and the effects of Se on the accumulation of carbohydrates, growth and yield in potato plants. An additional aim was to study the impact of Se on the total glycoalkaloid concentration in immature potato tubers. The distribution of Se in different biochemical Se fractions and the effect of storage on the Se concentration were studied in Se-enriched tubers. Furthermore, the effect of Se on raw darkening and translocation of Se from seed tubers to the next tuber generation was investigated. Due to the established anti-ageing properties of Se, it was of interest to study if Se affects physiological age and growth vigour of seed tubers. The Se concentrations in the upper leaves, roots, stolons and tubers of potato increased with increasing Se supplementation. The highest Se concentration was reached in young upper leaves, roots and stolons, indicating that added selenate was efficiently utilized and taken up at an early stage. During the growing period the Se concentration declined in the aerial parts, roots and stolons of potato plants whereas an intensive accumulation took place in immature and mature tubers. Selenium increased carbohydrate accumulation in the young upper leaves and in stolons, roots and tubers at maturity. This could not be explained by increased production of photoassimilates as net photosynthesis did not differ among Se treatments. The Se treated plants produced higher tuber yields than control plants, and at the highest Se concentration (0.3 mg kg-1) lower numbers of larger tubers were harvested. Increased yield of Se treated plants suggested that Se may enhance the allocation of photoassimilates for tuber growth, acting as a strong sink for both Se and for carbohydrates. Similarly as for other plant species, the positive impact of Se on the yield of potato plants could be related to its antioxidative effect in delaying senescence. The highest Se supplementation (0.9 mg kg-1) slightly decreased the glycoalkaloid concentration of immature tubers. However, at this level the Se concentration in tubers was about 20 µg g-1 DW. A 100 g consumption of potato would provide about 500 mg of Se, which exceeds the upper safe intake level of 400 µg per day for human dietary. The low Se applications (0.0035 and 0.1 mg kg-1) diminished and retarded the degree of raw darkening in tubers stored for one and eight months, which can be attributed to the antioxidative properties of Se. The storage for 1 to 12 months did not affect the Se concentrations of tubers. In the Se enriched tubers Se was allocated to the organic Se fraction, indicating that it was incorporated into organic compounds in tubers. Elevated Se concentration in the next-generation tubers produced by the Se enriched seed tubers indicated that Se could be translocated from the seed tubers to the progeny. In the seed tubers stored for 8 months, at high levels, Se had some positive effects on the growth vigour of sprouts, but Se had no consistent effect on the growth vigour of seed tubers of optimal physiological age. These results indicate that Se is a beneficial trace element in potato plants that exerts a positive effect on yield formation and improves the processing and storage quality of table potato tubers. These positive effects of Se are, however, dependent on the Se concentration and the age of the potato plant and tuber.