Computing the Stochastic Complexity of Simple Probabilistic Graphical Models

Minimum Description Length (MDL) is an information-theoretic principle that can be used for model selection and other statistical inference tasks. There are various ways to use the principle in practice. One theoretically valid way is to use the normalized maximum likelihood (NML) criterion. Due to computational difficulties, this approach has not been used very often. This thesis presents efficient floating-point algorithms that make it possible to compute the NML for multinomial, Naive Bayes and Bayesian forest models. None of the presented algorithms rely on asymptotic analysis and with the first two model classes we also discuss how to compute exact rational number solutions.

Accumulation of point mutations and reassortment of genomic RNA segments are involved in the microevolution of Puumala hantavirus in a bank vole (Myodes glareolus) population

"The genetic diversity of Puumala hantavirus (PUUV) was studied in a local population of its natural host, the bank vole (Myodes glareolus). The trapping area (2.5x2.5 km) at Konnevesi, Central Finland, included 14 trapping sites, at least 500 m apart; altogether, 147 voles were captured during May and October 2005. Partial sequences of the S, M and L viral genome segments were recovered from 40 animals. Seven, 12 and 17 variants were detected for the S, M and L sequences, respectively; these represent new wild-type PUUV strains that belong to the Finnish genetic lineage. The genetic diversity of PUUV strains from Konnevesi was 0.2-4.9% for the S segment, 0.2-4.8% for the M segment and 0.2-9.7% for the L segment. Most nucleotide substitutions were synonymous and most deduced amino acid substitutions were conservative, probably due to strong stabilizing selection operating at the protein level. Based on both sequence markers and phylogenetic clustering, the S, M and L sequences could be assigned to two groups, 'A' and 'B'. Notably, not all bank voles carried S, M and L sequences belonging to the same group, i.e. SAMALA or SBMBLB.. A substantial proportion (8/40, 20%) of the newly characterized PUUV strains possessed reassortant genomes such as SBMALA, SAMBLB or SBMALB. These results suggest that at least some of the PUUV reassortants are viable and can survive in the presence of their parental strains."

Grönlannin mannerjäätikön tulevaisuus: merenpinnan nousu maailmanlaajuisesti ja Itämerellä

Sea level rise is among the most worrying consequences of climate change, and the biggest uncertainty of sea level predictions lies in the future behaviour of the ice sheets of Greenland and Antarctica. In this work, a literature review is made concerning the future of the Greenland ice sheet and the effect of its melting on Baltic Sea level. The relation between sea level and ice sheets is also considered more generally from a theoretical and historical point of view. Lately, surprisingly rapid changes in the amount of ice discharging into the sea have been observed along the coastal areas of the ice sheets, and the mass deficit of Greenland and West Antarctic ice sheets which are considered vulnerable to warming has been increasing from the 1990s. The changes are probably related to atmospheric or oceanic temperature variations which affect the flow speed of ice either via meltwater penetrating to the bottom of the ice sheet or via changes in the flow resistance generated by the floating parts of an ice stream. These phenomena are assumed to increase the mass deficit of the ice sheets in the warming climate; however, there is no comprehensive theory to explain and model them. Thus, it is not yet possible to make reliable predictions of the ice sheet contribution to sea level rise. On the grounds of the historical evidence it appears that sea level can rise rather rapidly, 1 2 metres per century, even during warm climate periods. Sea level rise projections of similar magnitude have been made with so-called semiempirical methods that are based on modelling the link between sea level and global mean temperature. Such a rapid rise would require considerable acceleration of the ice sheet flow. Stronger rise appears rather unlikely, among other things because the mountainous coastline restricts ice discharge from Greenland. The upper limit of sea level rise from Greenland alone has been estimated at half a metre by the end of this century. Due to changes in the Earth s gravity field, the sea level rise caused by melting ice is not spatially uniform. Near the melting ice sheet the sea level rise is considerably smaller than the global average, whereas farther away it is slightly greater than the average. Because of this phenomenon, the effect of the Greenland ice sheet on Baltic Sea level will probably be rather small during this century, 15 cm at most. Melting of the Antarctic ice sheet is clearly more dangerous for the Baltic Sea, but also very uncertain. It is likely that the sea level predictions will become more accurate in the near future as the ice sheet models develop.

The struggle for protection of environmental refugees: who's responsibility? Discourses from the United Nations and Non-governmental organizations

This thesis identifies, examines and problematizes some of the discourses that have so far come to light on the issue of protection for environmental refugees. By analyzing the discourses produced by the United Nations Office of the High Commissioner for Refugees (UNHCR) and two non-governmental organizations - the Environmental Justice Foundation (EJF) and Equity and Justice Working Group Bangladesh (EquityBD), I examine the struggling discourses that have emerged about how protection for environmental refugees has been interpreted. To do this, I rely on Ernesto Laclau and Chantal Mouffe's theory and method of discourse analysis. The results show that responsibilization is the main point of struggle in the discussions on the protection of environmental refugees. As a floating signifier, it was utilized by the discourses produced by the UNCHR and the selected NGOs in contingent ways and with different political objectives. The UNHCR discourse responsibilized both the environmental refugees for their own protection and the individual states. The EJF and EquityBD, by contrast, allocated responsibility for the protection of environmental refugees to the international community. These contingent understandings of responsibilization necessitated different justifications. While the EJF discourse relied on humanitarianism for the assistance of environmental refugees, the EquityBD discourse constructed a rights based, more permanent solution. The humanitarian based discourse of the EJF was found to be inextricably linked with the neoliberal discourse produced by the UNHCR. Both these discourses encouraged environmental refugees to stay in their homelands, undermining the politics of protection. Another way in which protection was undermined was by UNHCR's discourse on securitization. In this context, climate change induced displacement became threat to developed countries, the global economy and transnational classes. The struggling discourses about who/what has been allocated responsibility for the protection of environmental refugees also meant that identities of the displaced be constructed in specific ways. While the UNHCR discourse constructed as voluntary migrants and predators, the EJF and EquityBD discourses portrayed them as victims. However, even though the EJF discourse constructed them as victims, their reliance on humanitarianism could also be interpreted as a way of giving the environmental refugee a predator like identity. These discourses on responsibilization and identity formation clashed with each other in the aim of achieving a hegemonic position in discussions and debates about the protection of environmental refugees.

The struggle for protection of environmental refugees: who's responsibility? Discourses from the United Nations and Non-governmental organizations

This thesis identifies, examines and problematizes some of the discourses that have so far come to light on the issue of protection for environmental refugees. By analyzing the discourses produced by the United Nations Office of the High Commissioner for Refugees (UNHCR) and two non-governmental organizations - the Environmental Justice Foundation (EJF) and Equity and Justice Working Group Bangladesh (EquityBD), I examine the struggling discourses that have emerged about how protection for environmental refugees has been interpreted. To do this, I rely on Ernesto Laclau and Chantal Mouffe's theory and method of discourse analysis. The results show that responsibilization is the main point of struggle in the discussions on the protection of environmental refugees. As a floating signifier, it was utilized by the discourses produced by the UNCHR and the selected NGOs in contingent ways and with different political objectives. The UNHCR discourse responsibilized both the environmental refugees for their own protection and the individual states. The EJF and EquityBD, by contrast, allocated responsibility for the protection of environmental refugees to the international community. These contingent understandings of responsibilization necessitated different justifications. While the EJF discourse relied on humanitarianism for the assistance of environmental refugees, the EquityBD discourse constructed a rights based, more permanent solution. The humanitarian based discourse of the EJF was found to be inextricably linked with the neoliberal discourse produced by the UNHCR. Both these discourses encouraged environmental refugees to stay in their homelands, undermining the politics of protection. Another way in which protection was undermined was by UNHCR's discourse on securitization. In this context, climate change induced displacement became threat to developed countries, the global economy and transnational classes. The struggling discourses about who/what has been allocated responsibility for the protection of environmental refugees also meant that identities of the displaced be constructed in specific ways. While the UNHCR discourse constructed as voluntary migrants and predators, the EJF and EquityBD discourses portrayed them as victims. However, even though the EJF discourse constructed them as victims, their reliance on humanitarianism could also be interpreted as a way of giving the environmental refugee a predator like identity. These discourses on responsibilization and identity formation clashed with each other in the aim of achieving a hegemonic position in discussions and debates about the protection of environmental refugees.