Browsing by Subject "verkostoteoria"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Dunkel, Elias (Helsingin yliopisto, 2019)
    Objective. Depression can affect the elderly just as it can affect people of working age. However, depression has been shown to manifest differently in the elderly compared to people of other ages, and diagnosing depression in elderly patients isn’t always as straightforward, as it might be for other populations. In addition, research on depression of the elderly lags behind that of others, which makes the structures and quality of depression in the elderly an important subject of study. Network theory provides a novel way of conceptualizing mental health problems. Mental disorders are no longer seen to be caused by a latent factor, such as a disease, but rather, mental disorders are conceptualized as causal relations of the symptoms of the disorder. Thus, network theory provides a basis for identifying relevant causal symptoms of different disorders in different populations as potential targets for interventions. So far, the structures of symptom networks of depression have been studied with clinical populations of working aged adults. This study aims to uncover, if there are initial structural differences in the depression networks of elderly patients whose depressive symptoms have persisted or remitted over a three-year follow-up. Methods. The sample of this study was part of the Survey of Health and Ageing and Retirement in Europe (SHARE) research project. The sample consisted of 14,084 over 50-year-old Europeans, whose score on the EURO-D depression scale was over the limit of observable depression on their first time filling the questionnaire. The sample was then split into two groups based on if their depression had either persisted (n = 7770) or remitted (n = 6314) over a three-year follow-up. Comparative network analysis was then performed on the networks of depressive symptoms from the first time the subjects filled the questionnaire. Results and conclusions. The symptom networks of people with persisting depression had stronger and structurally different connections between symptoms than those of people whose depression had remitted. This finding was in line with the network theory of mental disorders, as well as prior research findings. Contrary to prior findings, controlling for the severity of depression nullified the differences of strength between the symptom networks of the two groups. This finding may indicate, that contrary to clinically depressed populations of working ages, the depression networks of the elderly do not exhibit structures that would, despite of the severity of depression, predict the persistence of depression over a three-year follow-up.
  • Halinen, Henri (Helsingin yliopisto, 2015)
    Objectives of the study Depression is one of the greatest factors to decrease the quality of life. However, its etiology has no clear scientific base. It has been thought that depression is a latent variable, but this view has been questioned. According to the network approach stressful life events are directly linked to depressive symptoms without a latent variable. Body image dissatisfaction is a more long-lasting and stable depressive symptom than the other symptoms. In addition, body image dissatisfaction predicts depression, but depression does not predict body image dissatisfaction. It is probable that body image dissatisfaction is linked to appearance. In this study I examine if different adverse effects of unattractive appearance are associated with body image dissatisfaction, when the level of depression is controlled. If this is true it would indicate that body image dissatisfaction cannot be explained by one-dimensional depression. In this study the adverse effects of unattractive appearance were low income level and living alone, which are both linked to unattractive appearance according to previous studies. Methods In this study there were 1638–2969 participants depending on the analysis. The Cardiovascular Risk in Young Finns Study was used as the research material. Item response theory model and logistic regression were used to examine differential item functioning (DIF) in this study. DIF appears when an item of some latent variable has different scores in different groups even if the groups have the same score in the latent variable. Therefore I examined if equally depressed people do differ in body image dissatisfaction if they belong to the low income or living alone groups. Results and conclusions According to this study it is possible that depression is not a one-dimensional phenomenon. Low income level and living alone were inked to depressive symptoms and body image dissatisfaction. In addition, income level was associated differently to body image dissatisfaction than other depressive symptoms [χ² = 459.01, P < 0.001]. Living alone was not. Regardless, questioning the one-dimensionality of depression demands same kind of examination of other depressive symptoms in the future research.
  • Heikkilä, Lotta (Helsingfors universitet, 2016)
    Objective. Depression is a prevalent mental disorder with negative impact on health and well-being. After decades of research, there remains a need for a better understanding of its etiology and developing its treatment. Network theory views depression as a heterogeneous system, as opposed to a unidimensional, latent factor that causes its symptoms. In network theory, depressive symptoms are assumed to differ in their risk factors, such as personality traits. High neuroticism is a well-known risk factor for depression while extraversion and conscientiousness protect from it. However, only a few studies have examined personality traits as risk factors for individual depressive symptoms. The purpose of this study was to examine whether individual depressive symptoms are predicted by different personality traits. Depressive symptoms were assumed to vary in their risk and protective factors. The connections were assumed to remain when controlling for the latent depression factor. Methods. The data used was a part of the Wisconsin Longitudinal Study (WLS) (N = 4852). Depressive symptoms were measured with CES-D (The Center for Epidemiological Studies - Depression Scale), which consists of 20 symptoms. Personality was measured with an abbreviated version of BFI-54 (Big Five Inventory). Personality was assessed in 1993 and depressive symptoms in 2004. Associations between personality traits and individual depressive symptoms were examined with ordinal regression analyses. To test whether the connections were locally independent of latent depression, an ordinal regression procedure for detecting differential item functioning (DIF) was used. Results and conclusions. Depressive symptoms differed in their personality risk and protective factors. Connections between personality traits and depressive symptoms could not be explained by a latent depression factor. High neuroticism was a risk factor while extraversion and conscientiousness were protective factors for several central and common symptoms of depression. Also openness to experience and agreeableness mostly protected from some depressive symptoms. The results apply to less severe depressive symptoms in the general population and support earlier findings of depressive symptoms having qualitative differences. Deeper knowledge on the risk and protective factors of individual depressive symptoms can contribute to the development of more specific methods for preventing and treating depression.
  • Lehto, Juhani (2001)
    Tutkielman aiheena on taajuuslisenssien tehokas allokointi. Teorian sovelluksena käytetään ajankohtaista kolmannen sukupolven matkaviestinlisenssien eli niin sanottujen UMTS-lisenssien jakoa. Tarkastelu lähtee liikkeelle siten, että arvioidaan markkinoille tulevien yritysten optimaalista määrää. Verrataan markkinoiden tasapainon mukaista yritysten määrää sosiaalisesti optimaaliseen yritysten määrään. Tarkastelua varten muodostetaan malli, jota voidaan kuvata kaksivaiheisena pelinä. Ensimmäisessä vaiheessa yritykset päättävät haluavatko ne tulla markkinoille, jonne pääsystä niiden on maksettava kiinteä maksu. Jos yritykset päätyvät markkinoille, siis vaiheeseen kaksi, niin tällöin ne pelaavat jotakin markkinapeliä, jonka tässä tapauksessa oletetaan olevan Cournot-peli. Seuraavaksi tarkastellaan tämän pääsymaksun vaikutusta yritysten määrään. Tätä varten muodostetaan hyvin yksinkertainen malli, jonka perusteella johtopäätökset tehdään. Lisäksi arvioidaan myös kuluttajan käyttäytymistä. Koska lisenssien jakamisen tavoitteena on mm. taloudellinen tehokkuus, tarkastellaan tutkielmassa tämänkin tavoitteen parhaiten toteuttavaa lisenssien allokointimenetelmää, huutokauppaa. Huutokaupan menestys lisenssien ja yleensä niukkojen resurssien tehokkaassa kohdentamisessa perustuu sen kykyyn antaa lisenssit niiden käyttöön, jotka arvostavat niitä eniten ja pystyvät myös parhaiten niitä hyödyntämään. Lisäksi tutkielmassa kuvataan lyhyesti UMTS -teknologiaa ja Englannin toteuttamia UMTS -lisenssien huutokauppoja.