74 resultados para 1455
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In the thesis I study various quantum coherence phenomena and create some of the foundations for a systematic coherence theory. So far, the approach to quantum coherence in science has been purely phenomenological. In my thesis I try to answer the question what quantum coherence is and how it should be approached within the framework of physics, the metatheory of physics and the terminology related to them. It is worth noticing that quantum coherence is a conserved quantity that can be exactly defined. I propose a way to define quantum coherence mathematically from the density matrix of the system. Degenerate quantum gases, i.e., Bose condensates and ultracold Fermi systems, form a good laboratory to study coherence, since their entropy is small and coherence is large, and thus they possess strong coherence phenomena. Concerning coherence phenomena in degenerate quantum gases, I concentrate in my thesis mainly on collective association from atoms to molecules, Rabi oscillations and decoherence. It appears that collective association and oscillations do not depend on the spin-statistics of particles. Moreover, I study the logical features of decoherence in closed systems via a simple spin-model. I argue that decoherence is a valid concept also in systems with a possibility to experience recoherence, i.e., Poincaré recurrences. Metatheoretically this is a remarkable result, since it justifies quantum cosmology: to study the whole universe (i.e., physical reality) purely quantum physically is meaningful and valid science, in which decoherence explains why the quantum physical universe appears to cosmologists and other scientists very classical-like. The study of the logical structure of closed systems also reveals that complex enough closed (physical) systems obey a principle that is similar to Gödel's incompleteness theorem of logic. According to the theorem it is impossible to describe completely a closed system within the system, and the inside and outside descriptions of the system can be remarkably different. Via understanding this feature it may be possible to comprehend coarse-graining better and to define uniquely the mutual entanglement of quantum systems.
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Superfluidity is perhaps one of the most remarkable observed macroscopic quantum effect. Superfluidity appears when a macroscopic number of particles occupies a single quantum state. Using modern experimental techniques one dark solitons) and vortices. There is a large literature on theoretical work studying the properties of such solitons using semiclassical methods. This thesis describes an alternative method for the study of superfluid solitons. The method used here is a holographic duality between a class of quantum field theories and gravitational theories. The classical limit of the gravitational system maps into a strong coupling limit of the quantum field theory. We use a holographic model of superfluidity to study solitons in these systems. One particularly appealing feature of this technique is that it allows us to take into account finite temperature effects in a large range of temperatures.
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Modern elementary particle physics is based on quantum field theories. Currently, our understanding is that, on the one hand, the smallest structures of matter and, on the other hand, the composition of the universe are based on quantum field theories which present the observable phenomena by describing particles as vibrations of the fields. The Standard Model of particle physics is a quantum field theory describing the electromagnetic, weak, and strong interactions in terms of a gauge field theory. However, it is believed that the Standard Model describes physics properly only up to a certain energy scale. This scale cannot be much larger than the so-called electroweak scale, i.e., the masses of the gauge fields W^+- and Z^0. Beyond this scale, the Standard Model has to be modified. In this dissertation, supersymmetric theories are used to tackle the problems of the Standard Model. For example, the quadratic divergences, which plague the Higgs boson mass in the Standard model, cancel in supersymmetric theories. Experimental facts concerning the neutrino sector indicate that the lepton number is violated in Nature. On the other hand, the lepton number violating Majorana neutrino masses can induce sneutrino-antisneutrino oscillations in any supersymmetric model. In this dissertation, I present some viable signals for detecting the sneutrino-antisneutrino oscillation at colliders. At the e-gamma collider (at the International Linear Collider), the numbers of the electron-sneutrino-antisneutrino oscillation signal events are quite high, and the backgrounds are quite small. A similar study for the LHC shows that, even though there are several backrounds, the sneutrino-antisneutrino oscillations can be detected. A useful asymmetry observable is introduced and studied. Usually, the oscillation probability formula where the sneutrinos are produced at rest is used. However, here, we study a general oscillation probability. The Lorentz factor and the distance at which the measurement is made inside the detector can have effects, especially when the sneutrino decay width is very small. These effects are demonstrated for a certain scenario at the LHC.
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Human activities extract and displace different substances and materials from the earth s crust, thus causing various environmental problems, such as climate change, acidification and eutrophication. As problems have become more complicated, more holistic measures that consider the origins and sources of pollutants have been called for. Industrial ecology is a field of science that forms a comprehensive framework for studying the interactions between the modern technological society and the environment. Industrial ecology considers humans and their technologies to be part of the natural environment, not separate from it. Industrial operations form natural systems that must also function as such within the constraints set by the biosphere. Industrial symbiosis (IS) is a central concept of industrial ecology. Industrial symbiosis studies look at the physical flows of materials and energy in local industrial systems. In an ideal IS, waste material and energy are exchanged by the actors of the system, thereby reducing the consumption of virgin material and energy inputs and the generation of waste and emissions. Companies are seen as part of the chains of suppliers and consumers that resemble those of natural ecosystems. The aim of this study was to analyse the environmental performance of an industrial symbiosis based on pulp and paper production, taking into account life cycle impacts as well. Life Cycle Assessment (LCA) is a tool for quantitatively and systematically evaluating the environmental aspects of a product, technology or service throughout its whole life cycle. Moreover, the Natural Step Sustainability Principles formed a conceptual framework for assessing the environmental performance of the case study symbiosis (Paper I). The environmental performance of the case study symbiosis was compared to four counterfactual reference scenarios in which the actors of the symbiosis operated on their own. The research methods used were process-based life cycle assessment (LCA) (Papers II and III) and hybrid LCA, which combines both process and input-output LCA (Paper IV). The results showed that the environmental impacts caused by the extraction and processing of the materials and the energy used by the symbiosis were considerable. If only the direct emissions and resource use of the symbiosis had been considered, less than half of the total environmental impacts of the system would have been taken into account. When the results were compared with the counterfactual reference scenarios, the net environmental impacts of the symbiosis were smaller than those of the reference scenarios. The reduction in environmental impacts was mainly due to changes in the way energy was produced. However, the results are sensitive to the way the reference scenarios are defined. LCA is a useful tool for assessing the overall environmental performance of industrial symbioses. It is recommended that in addition to the direct effects, the upstream impacts should be taken into account as well when assessing the environmental performance of industrial symbioses. Industrial symbiosis should be seen as part of the process of improving the environmental performance of a system. In some cases, it may be more efficient, from an environmental point of view, to focus on supply chain management instead.
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Määräaikaisiin työsuhteisiin liittyvä epävarmuus on useiden tutkimusten mukaan yhteydessä stressiin ja vähentää psyykkistä hyvinvointia. Suomessa määräaikaiset työsuhteet ovat hieman yleisempiä kuin EU:ssa keskimäärin. Erityistä Suomen tilanteelle on se, että suomalaiset määräaikaiset palkansaajat ovat varsin koulutettuja eurooppalaisiin vertaisiinsa verrattuna. Yliopistoissa poikkeuksellisen suuri osa tekee työtä määräaikaisessa työsuhteessa. TUULI-kehittämishanke (2008–2011) toteutettiin Kuntoutussäätiön Malminkartanon kuntoutuskeskuksessa (syksystä 2010 Avire-Kuntoutus Oy), ja se oli tarkoitettu Helsingin yliopistossa määräaikaisissa palvelussuhteissa tai apurahalla työskenteleville henkilöille. Hankkeen rahoittivat Kela ja Työsuojelurahasto. Hankkeen arviointi toteutettiin Kuntoutussäätiön tutkimus- ja kehittämisyksikössä, ja arvioinnin rahoitti Kela. Hanke liittyi laajempaan Kelan toteuttamaan työhönkuntoutuksen kehittämishankkeeseen. Kuntoutusmalli TUULIn kohderyhmänä olivat Helsingin yliopiston akateemisesti koulutetut henkilöt, jotka ovat määräaikaisissa ja usein projektiluonteisissa työtehtävissä. Tämän kohderyhmän kuntoutustarvetta ei arvioida systemaattisesti työterveyshuollossa eikä työvoimatoimistossa. Osa kohderyhmään kuuluvista henkilöistä ei ole oikeutettu käyttämään työterveyshuollon palveluja, ja määräaikaisten työsuhteiden vuoksi he eivät myöskään valikoidu varhaiskuntoutukseen. Kuntoutusmalli TUULIn tavoitteena oli löytää kohderyhmälle soveltuvia kuntoutustarpeen arviointikeinoja (hyvinvointianalyysi). Tavoitteena oli myös kehittää kohderyhmälle soveltuva varhaiskuntoutusmuoto, johon määräaikaisissa työsuhteissa olevien on käytännössä mahdollista osallistua. Arvioinnissa keskeistä oli kehittävä arviointi, toisin sanoen tavoitteena oli myös tukea hankkeen toimintaa sen tavoitteiden toteuttamisessa ja kuntoutusmallin kehittämisessä. Arviointitutkimuksen tavoitteena oli tuottaa kokonaisarviointi TUULI-kuntoutusmallista. Hankkeen aluksi koottiin perustiedot sekä varsinaiseen interventioon osallistuvilta että ainoastaan hyvinvointianalyysiin osallistuneilta asiakkailta. Myös hankkeen päättyessä koottiin seurantatiedot molemmilta ryhmiltä. Jokainen kuntoutusryhmä on lisäksi haastateltu viimeisen seitsemän vuorokauden intensiivijaksoon kuuluvan päivän aikana. Arvioinnin aikana tehtiin osallistavaa yhteistyötä erityisesti hankkeen toteuttajien, ohjausryhmän ja rahoittajatahojen kanssa. Hyvinvointianalyysiin ja kuntoutusinterventioon saatiin rekrytoitua tavoiteltu määrä osallistujia. He kokivat määräaikaisuuteen liittyvän epätietoisuuden haittaavan työssä jaksamista. Hieman vajaa kolmasosa koki tämän haittaavan paljon. Selvä enemmistö raportoi työn henkisen kuormituksen ongelmista. Hyvinvointianalyysin ohjelma koostui sydämen sykevariaatioanalyysistä, psykologisista testeistä, lääkärin tutkimuksesta ja palautekeskustelusta. Hyvinvointianalyysi koettiin osallistujien keskuudessa varsin hyödylliseksi toimenpiteeksi. Koettu hyöty näyttäisi olevan samalla tasolla myös yhdeksän kuukautta hyvinvointianalyysin päättymisestä. Hyvinvointianalyysi toimi kuntoutustarpeen arviointivälineenä ja itsenäisenä mini-interventiona. Kuntoutusinterventiossa keskeisiä osa-alueita olivat stressin hallinnan ja rentoutumisen opetteleminen, oman työn kuormitustekijöiden tunnistaminen sekä psyykkisen hyvinvoinnin ja omien voimavarojen vahvistaminen. Myös kuntoutusintervention jälkeen osallistujien kokemukset olivat enimmäkseen positiivisia: he kokivat intervention kohentavan kykyään huolehtia omasta hyvinvoinnistaan sekä vahvistavan psyykkisiä ja sosiaalisia voimavarojaan ja stressin hallintaa. Myös työkyvyn koettiin kohentuneen. Sen sijaan osallistujat eivät kokeneet toiminnan ja työn tehokkuuden taitojen kohenneen. Toteuttajat arvioivat hankkeen saavuttaneen keskeisimmät tavoitteensa. Pätkätyöläisen ammatillisen identiteetin hahmottaminen ja työstäminen koettiin ongelmalliseksi; kehittämishankkeen aikana ei löydetty varteenotettavaa lähestymistapaa aiheeseen. Kuntoutusjärjestelmää tulee kehittää huomioiden työn ja työelämän muutokset. TUULI-hanke oli hyvä avaus tällä saralla, mutta hanke oli suunnattu vain pienelle osalle epätyypillistä työtä tekevien joukkoa. Koska määräaikainen työ on vakiintunut osaksi työmarkkinoita ja pätkistä koostuvaan työuraan liittyy työttömyysjaksoja, tulisi myös työttömyyskaudella olevat saada kuntoutusjärjestelmän piiriin. Arvioinnin kehittämissuositukset huomioiva TUULI-kuntoutusmalli tulisi toteuttaa ainakin kertaalleen Suomen yliopistoissa.
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This study examines the diaconia work of the Finnish Evangelical Lutheran Church from the standpoint of clients. The role of diaconia work has grown since the early 1990s recession, and since it established itself as one of the actors along with other social organizations. Previous studies have described the changing role of diaconal work, especially from the standpoint of diaconia workers and co-operators. This research goes back to examine, beyond the activities of the diaconia work of everyday practices, its relations of ruling which are determining practices. The theoretical and methodological framework rises from the thinking of Dorothy E. Smith, the creator of institutional ethnography. Its origins are in feminism, Marxism, phenomenology, etnomethodology, and symbolic interactionism. However, it does not represent any school. Unlike the objectivity-based traditional sociology, institutional ethnography has its starting point in everyday life, and people s subjective experience of it. Everyday life is just a starting point, and is used to examine everyday life s experiences of hidden relations of ruling, linking people and organizations. The level of generalization is just on the relations of ruling. The research task is to examine those meanings of diaconia work which are embedded in its clients experiences. The research task is investigated with two questions: how diaconia work among its clients takes shape and what kinds of relations of ruling exist in diaconia work. The meanings of diaconia work come through an examination of the relations of ruling, which create new forms of diaconal work compared with previous studies. For the study, two kinds of data were collected: a questionnaire and ethnographic fieldwork. The first data set was collected from diaconal workers using the questionnaire. It gives background information of the diaconia work process from the standpoint of the clients. In the ethnographic study there were two phases. The first ethnographic material was collected from one local parish by observing, interviewing clients and diaconal workers and gathering documents. The number of observations was 36 customer appointments, and 29 interviews. The second ethnographic material was included as a part of the analysis, in which ruling relations in people s experiences were collected from the transcribed data. Close reading and narrative analysis are used as analysing methods. The analysis has three phases. First, the experiences are identified with close reading; the following step is to select some of the institutional processes that are shaping those experiences and are relevant for the research. At the third stage, those processes are investigated in order to describe analytically how they determine people s experience. The analysis produces another narrative about diaconia work, which provides tools for examining the diaconal work from a new perspective. Through the analysis it is possible to see diaconia as an exchange ratio, in which the exchange takes place between a client and a diaconia worker, but also more broadly with other actors, such as social workers, shop clerks, or with other parishioners. The exchange ratio is examined from the perspective of power which is embedded in the client s experiences. The analysis reveals that the most important relations of ruling are humiliation and randomness in the exchange ratio of diaconia work; valuating spirituality above the bodily being; and replacing official social work. The results give a map about the relations of ruling of diaconia work which gives tools to look at diaconia work s meanings to the clients. The hidden element of humiliation in the exchange ratio breaks the current picture of diaconia work. The ethos of the holistic encounters and empathic practices are shown to be of another kind when spirituality is preferred to the bodily being. Nevertheless, diaconia appears to be a place for a respectful encounter, especially in situations where the public sector s actors are retreating on liability or clients are in a life crisis. The collapse of the welfare state structures imposes on diaconia work tasks that have not previously belonged to it. At the local level, clients receive partners from diaconia workers in order to advocate them in the welfare system. Actions to influence the wider societal structures are not reached because of lacking resources. An awareness of the oppressive practices of diaconia work and their critical reviewing are the keys to the development of diaconia work, since there are such practices even in holistic and respectful diaconia work. While the research raises new information for the development of diaconia work, it also opens up new aspects for developing other kinds of social work by emphasizing the importance of taking people s experiences seriously. Keywords: diaconia work, institutional ethnography, Dorothy E. Smith, experience, customer, relations of ruling.
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This thesis critically examines the patterns and processes of ethnic residential segregation in the Helsinki Metropolitan Area (HMA). These phenomena are examined in two main ways: a) between the native and immigrant populations and b) the extent to which different immigrant groups are sharing the same neighbourhoods. The main aim of the study is to test the extent to which the theoretical claims of the selective migration processes can explain the development of ethnic residential segregation in HMA. The data is mixed: it consists of neighbourhood-level statistics related to the migration, demography and housing stock. The selective migration flows are analysed within and between neighbourhood-types, defined on the basis of the percentages of foreign-language-speakers. For contextual purposes, the study also includes fifteen expert interviews who work within the housing sector. Firstly, the results show that, from the early 2000s the patterns of ethnic residential segregation have strengthened while the differences between neighbourhoods have grown. On a more general level the HMA can be divided into two main areas: some eastern and north-eastern neighbourhoods that have experienced the rise of immigrant concentrations and; the northern, north-western and southern parts of the HMA, where the number and percentages of immigrants have remained relatively low. However, within the eastern and north-eastern neighbourhoods there are also discernable internal differences that reflect the income levels of the inhabitants and the type of housing stock. The results also show that, the existing immigrant concentrations are ethnically and culturally mixed and thus qualitatively different from China town and Little-Italy enclaves of single groups of immigrants. Secondly, the results show that there are clear signs of the selective migration processes of the native and immigrant populations which have resulted in the discernable development of ethnic residential segregation. Migration flows of the native population have gravitated towards neighbourhoods, where the percentage of immigrants is below the HMA average. This has resulted in significant migration losses for neighbourhoods with established and developing concentrations of immigrants. Meanwhile, migration of immigrants has been drawn to neighbourhoods where their percentages are above the HMA average. However, the results also point to clear differences in the migration and spatial patterns of different immigrant groups. The spatial selectivity of migration is, thus, more prominent amongst the native population than when compared with immigrants. Overall, the results indicate that the reproduction of the selective migration flows of the native and immigrant populations will largely determine HMA s future development of ethnic residential segregation.
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