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Hopea on kiiltävä metalli, jota käytetään paljon koruissa, aterimissa ja erilaisissa elektroniikan laitteissa. Hopea reagoi helposti ilmassa olevien rikkiyhdisteiden kanssa, mistä johtuu hopeaesineiden tummuminen ajan kuluessa. Hopean pääkorroosiotuote on hopeasulfidi, mutta myös hopeakloridi on yleinen varsinkin meri-ilmastossa. Tummumisen estämiseksi hopeaa on seostettu muilla alkuaineilla. Korroosionkestävistä metalliseoksista tutkituimpia ovat hopean ja palladiumin seokset, joita on käytetty erityisesti hammaslääketieteessä. Hopea voidaan myös suojata erilaisilla pinnoitteilla, jotka estävät hopean reaktion eri yhdisteiden kanssa. Hopean suojaamiseksi on käytetty perinteisesti orgaanisia lakkoja, kuten selluloosanitraattia. Hopeaa on pinnoitettu myös muilla orgaanisilla pinnoitteilla, kuten polymeereillä ja tioleilla. Tiolit muodostavat itsejärjestyviä monokerroksia hopean pinnalle. Näiden kalvojen suoja perustuu vahvaan Ag-S-sidokseen ja pitkään hydrofobiseen hiilivetyketjuun. Hopeaa on pinnoitettu myös ohuilla metallioksidi- tai nitridikalvoilla. Metallipinnan esikäsittelyn on havaittu parantavan kalvojen passivoitumisominaisuuksia. Tutkielman kirjallisessa osuudessa käsitellään hopean tummumiseen vaikuttavia tekijöitä sekä esitellään hopean passivoinnissa käytettyjä menetelmiä. Kokeellisessa osuudessa tutkitaan hopean passivointia näkymättömillä ALD-menetelmällä valmistetuilla pinnoitteilla. Höyrystetyille hopeapeileille kasvatettiin ALD-menetelmällä erilaisia pinnoitteita alumiinioksidista, tantaalioksidista ja titaanioksidista. Pinnoitetuille hopeapeileille tehtiin EN ISO 4538-standardin mukainen tioasetamidikorroosiokoe, jossa hopeat altistuivat rikkivedylle. Hopeapeilit valokuvattiin ja niiden heijastus mitattiin ennen altistusta ja säännöllisin aikavälein altistuskokeen aikana. Paras suoja saavutettiin alumiinioksidin ja tantaalioksidin nanolaminaattirakenteisella pinnoitteella, jonka paksuus oli noin 60 nm.

Although hot particles can be released to the environment via many pathways (nuclear accidents, warfare, industry), the understanding of their behavior in the human body, as well as their consequent health impacts. This study aims to understand how uranium particles (UO2 particles) and particles derived from nuclear accidents (Cesium-rich Micro-Particles, CsMPs) behave chemically after inhalation and how they impact human lungs. Specifically, the study aims to ascertain the duration of particle persistence within tissues post-inhalation, investigate the likelihood of translocation or chemical modifications, and evaluate both the chemical and possible radiobiological risks posed to organisms. To achieve this objective, the physicochemical alterations of UO2 particles and CsMPs after exposure to simulated lung fluids and their resulting cytotoxicity in cell models are studied. Dissolution studies are conducted, first using simulated lung fluid (SLF), that represents the interstitial lung fluid in the lung alveolar, followed by artificial lysosomal fluid (ALF), which mimics the conditions particles encounter after internalization by alveolar macrophages. Particle solubility is assessed using chemical analytical techniques (ICP-MS). Thus, the potential dissolution of these particles or their ability to persist as intact point sources of radiation over extended periods is explored. Particles after dissolution are examined using SEM-EDX analysis to study changes in the surface morphology and chemical composition. Additionally, the initial uptake and cytotoxic effects of these particles is investigated using murine lung fibroblast and macrophage cell lines, aiming to establish a detailed understanding of their radio- and chemical toxicity. UO2 particles presented minimal dissolution in SLF(< 2% of U dissolved) during 60 days of dissolution and a formation of a secondary phase on the surface of the particle was observed (mineral of uranyl associated with phosphates, most likely autunite). After exposure to ALF for 30 days, UO2 particles dissolved extensively ( ̴ 90% of U dissolved). From the single-particle dissolution for the CsMPs generated from the Fukushima-Daiichi accident, preliminary data has shown that within 30 days, a range of 10-25% of Cs-137 was leached into the SLF solution. Modified UO2 (after dissolution in SLF for 10 days, 180 days or ALF for 30 days) shown similar cell cytotoxicity profile as unmodified UO2 particles (20-40% cell viability after 24 hours).

In many Sub-Saharan countries, including Tanzania, people living in rural areas have difficult access to clean water and adequate sanitation. In these areas, traditionally women are responsible for the collecting of water and domestic activities, but at the same time they are not involved in the public decision making. Therefore, a focus on gender has become relevant in development aid practices, including project evaluation. Evaluation helps assessing relevance, efficiency, effectiveness, impact and sustainability of the implemented actions, compared with the proposed outcomes. Furthermore evaluation procedures of water and sanitation development projects should not ignore spatial factors, which are intertwined with societal factors in the operational environment of development projects. This requires acknowledging that interaction between gendered subjectivities and spatial and societal factors produces and reproduces gendered spaces. More particularly, this thesis considers a case study of a rural development project based in Kishapu District, northern Tanzania, implemented by Tanganyika Christian Refugee Service (TCRS). An evaluation framework is formed and used for unofficial evaluation of the project component in household water supply and sanitation. The framework has its emphasis in the beneficiaries of the development project and in gender equality, which are central for social sustainability. Emphasising social sustainability also furthers realisation of environmental sustainability. This research applies mixed methods, using both qualitative and quantitative analysis. The main data consists of semi structured stakeholder interviews, analysed using content analysis. The data includes also field observations, discussions, and GPS coordinated (geotagged) photographs of the main water sources. Development project documents are used as supporting material for the evaluation. An evaluative approach can be used as a scientific method in development geography, providing a critical viewpoint to the research and helping to connect research results with practical solutions. Evaluation shows the importance of exploring the views and knowledge of the beneficiaries. Through evaluation one can discover the positive effects, possible failures and possible future improvements and the sustainability of a development project. The household water and sanitation sector is a combined field revealing different gender needs that are rarely addressed in any development project, such as the use of toilets, or issues related to menstrual hygiene. There is a need to analyse how space is gendered and what kind of changes the development initiatives cause. For example, in the case study area of this thesis, there was clearly an attempt for public space to be more open to women, but the traditional division of public space being masculine and private space feminine was still dominant in practice. There is a need for change, because this division limits the participation of women and their ability to bring out their needs. The gendered division of space also limits the participation of men in training programs and activities relating to private space, which includes trainings related to household water, sanitation and hygiene.

A significant number of people have problems with the batteries of their mobile devices. There are several energy saving applications available to tackle those problems. Most of them increase battery life mostly by automatically closing applications or operations. The user is for the most part unaware of what the energy saving application actually does. Therefore, even though the battery might last somewhat longer, the user may continue using behavioral patterns that drain the battery. There is little evidence to support the assumption that battery awareness applications lead to behavioral changes. Therefore, we decided to conduct a research on how a mobile awareness application called Carat is used, and how the behavior of its users changes over time. The study was carried out in two phases. In the first part of the study, we conducted a user survey, and studied the Carat log data of the devices represented in the survey. We found out that the behavior changes over time; there were significant differences between new Carat users, and the more experienced ones. The more experienced users had reduced their use of problematic applications more, were interested in different features of Carat, and opened it less often. In the second part of the study, we studied how new Carat users used Carat and what they thought of using it. They were interviewed twice, and they also wrote in a web diary about their experiences. We found out that the main difference in their thinking was the increase in overall awareness about applications as something that affects battery life. We also found out that inadequate, uninteresting and unclear information causes confusion and frustration, and decreases the likelihood of users sticking with Carat.

Online social networks have brought along much convenience to our daily lives. On the other hand, they also provide platforms for the rapid propagation of unsafe content. Providing easy-to-use ways for ordinary users to avoid unsafe content online is an open issue. In this thesis, we mainly study two schemes that are based on social navigation to identify unsafe content. The first one is crowdsourcing, which has two main drawbacks: (a) a time lag before unsafe content is flagged as such, and (b) the difficulty of dealing with subjective perceptions of 'inappropriateness''. We propose a machine learning approach to address the time lag problem and get a promising result. This approach could be used to complement crowdsourcing. We also study the notion of 'groupsourcing'': taking advantage of information from people in a user's social circles about potentially unsafe content. Groupsourcing can both address the time lag problem and identify inappropriate content. To test its effectiveness, we have implemented FAR, which allows savvy Facebook users to warn their friends about potentially unsafe content, and conducted a controlled laboratory study. The results show that groupsourced signals can complement other types of signals and compensate for their weaknesses by countering viral spreading of unsafe content in a more timely fashion. The current version of FAR, consisting of a Facebook application and a Firefox browser extension is publicly available for use.

Steam power revolutionized shipping in the beginning of the 19th century. At the local level, the new technology enabled faster water transport connections operated by predetermined time schedules and routes. The aim of this Master's thesis is to provide an overview of the beginning, development and end of the local steamboat traffic in Helsinki. The industrial breakthrough, which started during the second half of the 19th century, was followed by a rapid population growth and urbanization process which shaped the city and society in many different ways. The development of the steamboat traffic is viewed as part of this urbanization process. In the actual study section of the thesis, I have examined the settlement development along the steamboat networks from the 1890s to the 1930s. The subject of the study can be classified as historical geography, transport geography and urban geography. The study is descriptive. A model designating the relationship between urban transport systems and the spatial form and organization of the city is adopted as the theoretical framework of the study. The research material consists of literature, historical maps and timetables. Maps produced based on historical spatial information illustrates the changes in the urban structure of the city. The study shows that local steamboats primarily served as a transportation mode related to different leisure activities for the urban residents. The regular water transport connections created conditions for the expansion of the summer villa settlement and later the steamboats also maintained transportation to a number of people`s parks established in the1920s and 1930s. Local steamboat transportation networks, along with other urban transportation modes contributed to the urban development and expansion of Helsinki, though their role has been marginal compared to other modes of transport. Still today, many of the villas built in the turn of the 19th and the 20th centuries are part of the maritime landscape of Helsinki. Several of the remaining villa areas are classified as nationally significant built cultural environment, which therefore also affects the land use in the future. Many of the people`s parks established in the early 20th century are still in recreational use. The transportation connections to the recreational islands is today maintained by motorized water-buses. Steamboat traffic has thus, at least indirectly, affected the landscape of the coastal areas and islands of the Helsinki archipelago.

We determine the leading thermal contributions to various self-energies in finite-temperature and -density quantum chromodynamics (QCD). The so-called hard thermal loop (HTL) self-energies are calculated for the quark and gluon fields at one-loop order and for the photon field at two-loop order using the real-time formulation of thermal field theory. In-medium screening effects arising at long wavelengths necessitate the reorganization of perturbative series of thermodynamic quantities. Our results may be directly applied in a reorganization called the HTL resummation, which applies an effective theory for the long-wavelength modes in the medium. The photonic result provides a partial next-to-leading order correction to the current leading-order result and can be later extended to pure QCD with the techniques we develop. The thesis is organized as follows. First, by considering a complex scalar field, we review the main aspects of the equilibrium real-time formalism to build a solid foundation for our thermal field theoretic calculations. Then, these concepts are generalized to QCD, and the properties of the QCD self-energies are thoroughly studied. We discuss the long-wavelength collective behavior of thermal QCD and introduce the HTL theory, outlining also the main motivations for our calculations. The explicit computations of self-energies are presented in extensive detail to highlight the computational techniques we employ.

We begin by discussing the essential concepts within the standard cosmology where the dark matter is "cold" and collisionless. We consider the structure formation in the dark matter component and present problems faced by the standard cosmology as well as some prospects for the solutions to those. The main problem considered in this work is the tension in the value of the Hubble constant measured with different procedures. We present the theories behind the procedures, and conclude the study of the tension by considering the most notable interpretations for the reason behind it. We then set up a proposal for an alternative model describing the dark sector. It is a hidden copy of the visible sector electromagnetism, allowing for a radiative cooling in virializing structures. By assuming first an asymmetric particle content, we study which scales of the dark matter halos are eligible to collapse into dense structure. Acquiring a mass function then allows to conclude how much from the total dark matter component is expected to collapse. If instead the dark matter particle content is taken to be symmetric, the collapsed fraction is assumed to annihilate into dark radiation. With certain modifications to the freely available Boltzmann code CAMB, we construct to the code a representation of the cosmology defined by our model. Lastly we use the modified cosmology to create a fit to the data defining the Hubble constant, and see for the relief of the tension. We find that our model provides a reasonable history for the energy content of the universe, and a notable relief to the Hubble tension, although the improvement is only a minor one compared to some more modest modifications to the cosmology.

A high-resolution grain size analysis was carried out on a 2,5 meter long marine core series from Isvika Bay, Nordauslandet, Svalbard. Grain size analysis was performed with a Malvern Mastersizer 2000 laser grain size analysator. The analysis of the results was determined by the relative proportions of sand (greater than 63 microns), silt (8-63 microns) and clay (less than 8 microns). Clay, silt and sand proportions were made in to a triangle diagram. On certain depths a model diagram was taken and its curves were examined. The material was determined by the following standard deviations (d₁₀, d₂₅, d₃₀, d₅₀, d₆₀, d₇₅ ja d₉₀), which were calculated to parameters: the coefficient of uniformity (Cu), the coefficient of curvature (Cc), standard deviation (So), skewness (Sk), and kurtosis (K). The modes were obtained directly from the Malvern software results. In addition, graphs of interpenetration rates dd₅₀ and d₉₀ were made. The grain size of the marine sediment core gave a comprehensive picture of the sedimentation of the last 11700 years in Isvika Bay. IRD-material of over 500 microns accumulates almost the entire time series. IRD's minimum sections describe a momentarily colder period in the climate, which lead to the freezing of the sea and the perennial sea ice. These colder periods prevented sea ice and icebergs importing IRD-material to Isvika Bay. These cold 25-80 years lasting periods have been 10300, 8300, 6700, 5700, 2000, 1200, 500, 300 and 200 cal. years BP. The intervals of cold phases have been on an average of 1150 years. Based to grain size distribution 11700 – 9400 cal. years BP, stable sedimentation environment and cold climate prevailed. 9500 cal. years BP there has been strong warming. 9500 – 7500 cal. years BP, there has been a warm climate, which led to an intensive glacier melting. 7500 – 4500 cal. years BP, the climate got colder for several thousands of years. 4500-4000 cal. years BP the climate got warmer for a period of about 500 years. The climate cooled down gradually between 4000 – 500 cal. years BP toward the present time. The last 500 years the climate has been warmer than the previous, but very variable. During this time, the presence of the multi-annual sea ice has declined.

Urban greenery is vital to the people in our increasingly urbanizing societies. It is diverse in nature and provides numerous life improving qualities. Traditionally urban greenery has been assessed with a top-down view through the sensors of aerial vehicles and satellites. This does not equate on what is experienced down at the human level. An alternative viewpoint has emerged, with the introduction of a more human-scale viewpoint. To quantify this human-scale greenery, novel and disparate approaches have been developed. However, there is little knowledge on how these modelling methods and indices manage to capture the greenery we truly experience on the ground level. This thesis is an undertaking to better understand what the greenery experienced by people on the ground level, termed humanscale greenery (HSG), means. The goal was to grasp how the various modelling methods, indices and datasets can be best used to capture this phenomenon. Simultaneously, the study tries to better comprehend how different people experience greenery. To achieve this, human-scale greenery values were collected via interviews at randomly selected study sites across Helsinki. These values were then compared to modelled values at the same sites. The methods and indices tested include modern approaches developed specifically for HSG and traditional greenery assessment methods. Along the greenery values, sociodemographic variables were collected in the interviews and compared to each other in relation to HSG values. The modelled values were on average smaller than HSG values. All methods indicated very strong or strong linear relationships with human-scale greenery. NDVI and semantic segmentation Green View Index (GVI) had the strongest relationships and least deviation. Land use (LU) and color based GVI had the highest error deviations from HSG. The sociodemographic assessment showed hints that age might affect the amount of experienced greenery, but this is uncertain. With a random sampling of interviewees, 25–34-year-olds and less nature visiting people were more common at sites with low HSG. Based on the results obtained here, many different types of novel methods are suitable for modelling HSG with strong linear relationships. However, also traditional greenery assessment methods performed well. It is difficult to curtail the experience of greenery into a single approach. A solution could possibly be obtained via the combination of methods. The results also advocate the usage of machine learning methods for greenery image segmentation. These cannot be applied everywhere due to data coverage problems, but alternative methods can also be used to fill in gaps. The significance of age on the experience of greenery needs further research. Because urban greenery’s benefits are known, attention should also be given onto how different kinds of people are able to experience it. In the future we should also discuss the meaningfulness of assessing absolute greenery in comparison to the types and parts of greenery.