961 resultados para Reasons
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Hall thrusters, such as Stationary Plasma Thruster (SPT), have been widely used on board modern satellites placed in geo-synchronows orbits for reasons such as orbit maintenance, repositioning and attitude control. In order to study the performance of the stationary plasma thruster, the thrust produced by it has been measured, using a thrust balance with strain gauge sensors under vacuum conditions, by activating the thruster. This activation of thruster has been carried out by switching ON and switching OFF of the necessary power supplies and control of other feed system such as the propellant flow in a particular sequence. Hitherto, these operations were done manually in the required sequence. This paper reports the attempt made to automate the sequential operation of the power supplies and the necessary control valves of the feed system using Intel 8051 microcontroller. This automation has made thrust measurements easier and more sophisticated.
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In this thesis I examine the U.S. foreign policy discussion that followed the war between Russia and Georgia in August 2008. In the politically charged setting that preceded the presidential elections, the subject of the debate was not only Washington's response to the crisis in the Caucasus but, more generally, the direction of U.S. foreign policy after the presidency of George W. Bush. As of November 2010, the reasons for and consequences of the Russia-Georgia war continue to be contested. My thesis demonstrates that there were already a number of different stories about the conflict immediately after the outbreak of hostilities. I want to argue that among these stories one can discern a “neoconservative narrative” that described the war as a confrontation between the East and the West and considered it as a test for Washington’s global leadership. I draw on the theory of securitization, particularly on a framework introduced by Holger Stritzel. Accordingly, I consider statements about the conflict as “threat texts” and analyze these based on the existing discursive context, the performative force of the threat texts and the positional power of the actors presenting them. My thesis suggests that a notion of narrativity can complement Stritzel’s securitization framework and take it further. Threat texts are established as narratives by attaching causal connections, meaning and actorship to the discourse. By focusing on this process I want to shed light on the relationship between the text and the context, capture the time dimension of a speech act articulation and help to explain how some interpretations of the conflict are privileged and others marginalized. I develop the theoretical discussion through an empirical analysis of the neoconservative narrative. Drawing on Stritzel’s framework, I argue that the internal logic of the narrative which was presented as self-evident can be analyzed in its historicity. Asking what was perceived to be at stake in the conflict, how the narrative was formed and what purposes it served also reveals the possibility for alternative explanations. My main source material consists of transcripts of think tank seminars organized in Washington, D.C. in August 2008. In addition, I resort to the foreign policy discussion in the mainstream media.
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The evacuation of Finnish children to Sweden during WW II has often been called a small migration . Historical research on this subject is scarce, considering the great number of children involved. The present research has applied, apart from the traditional archive research, the framework of history-culture developed by Rüsen in order to have an all-inclusive approach to the impact of this historical event. The framework has three dimensions: political, aesthetic and cognitive. The collective memory of war children has also been discussed. The research looks for political factors involved in the evacuations during the Winter War and the Continuation War and the post-war period. The approach is wider than a purely humanitarian one. Political factors have had an impact in both Finland and Sweden, beginning from the decision-making process and ending with the discussion of the unexpected consequences of the evacuations in the Finnish Parliament in 1950. The Winter War (30.11.1939 13.3.1940) witnessed the first child transports. These were also the model for future decision making. The transports were begun on the initiative of Swedes Maja Sandler, the wife of the resigned minister of foreign affairs Rickard Sandler, and Hanna Rydh-Munck af Rosenschöld , but this activity was soon accepted by the Swedish government because the humanitarian help in the form of child transports lightened the political burden of Prime Minister Hansson, who was not willing to help Finland militarily. It was help that Finland never asked for and it was rejected at the beginning. The negative response of Minister Juho Koivisto was not taken very seriously. The political forces in Finland supporting child transports were stronger than those rejecting them. The major politicians in support belonged to Finland´s Swedish minority. In addition, close to 1 000 Finnish children remained in Sweden after the Winter War. No analysis was made of the reasons why these children did not return home. A committee set up to help Finland and Norway was established in Sweden in 1941. Its chairman was Torsten Nothin, an influential Swedish politician. In December 1941 he appealed to the Swedish government to provide help to Finnish children under the authority of The International Red Cross. This plea had no results. The delivery of great amounts of food to Finland, which was now at war with Great Britain, had automatically caused reactions among the allies against the Swedish imports through Gothenburg. This included the import of oil, which was essential for the Swedish navy and air force. Oil was later used successfully to force a reduction in commerce between Sweden and Finland. The contradiction between Sweden´s essential political interests and humanitarian help was solved in a way that did not harm the country´s vital political interests. Instead of delivering help to Finland, Finnish children were transported to Sweden through the organisations that had already been created. At the beginning of the Continuation War (25.6.1941 27.4.1945) negative opinion regarding child transports re-emerged in Finland. Karl-August Fagerholm implemented the transports in September 1941. In 1942, members of the conservative parties in the Finnish Parliament expressed their fear of losing the children to the Swedes. They suggested that Finland should withdraw from the inter-Nordic agreement, according to which the adoptions were approved by the court of the country where the child resided. This initiative failed. Paavo Virkkunen, an influential member of the conservative party Kokoomus in Finland, favoured the so-called good-father system, where help was delivered to Finland in the form of money and goods. Virkkunen was concerned about the consequences of a long stay in a Swedish family. The risk of losing the children was clear. The extreme conservative party (IKL, the Patriotic Movement of the Finnish People) wanted to alienate Finland from Sweden and bring Finland closer to Germany. Von Blücher, the German ambassador to Finland, had in his report to Berlin, mentioned the political consequences of the child transports. Among other things, they would bring Finland and Sweden closer to each other. He had also paid attention to the Nordic political orientation in Finland. He did not question or criticize the child transports. His main interest was to increase German political influence in Finland, and the Nordic political orientation was an obstacle. Fagerholm was politically ill-favoured by the Germans, because he had a strong Nordic political disposition and had criticised Germany´s activities in Norway. The criticism of child transports was at the same time criticism of Fagerholm. The official censorship organ of the Finnish government (VTL) denied the criticism of child transports in January 1942. The reasons were political. Statements made by members of the Finnish Parliament were also censored, because it was thought that they would offend the Swedes. In addition, the censorship organ used child transports as a means of active propaganda aimed at improving the relations between the two countries. The Finnish Parliament was informed in 1948 that about 15 000 Finnish children still remained in Sweden. These children would stay there permanently. In 1950 the members of the Agrarian Party in Finland stated that Finland should actively strive to get the children back. The party on the left (SKDL, the Democratic Movement of Finnish People) also focused on the unexpected consequences of the child transports. The Social Democrats, and largely Fagerholm, had been the main force in Finland behind the child transports. Members of the SKDL, controlled by Finland´s Communist Party, stated that the war time authorities were responsible for this war loss. Many of the Finnish parents could not get their children back despite repeated requests. The discussion of the problem became political, for example von Born, a member of the Swedish minority party RKP, related this problem to foreign policy by stating that the request to repatriate the Finnish children would have negative political consequences for the relations between Finland and Sweden. He emphasized expressing feelings of gratitude to the Swedes. After the war a new foreign policy was established by Prime Minister (1944 1946) and later President (1946 1956) Juho Kusti Paasikivi. The main cornerstone of this policy was to establish good relations with the Soviet Union. The other, often forgotten, cornerstone was to simultaneously establish good relations with other Nordic countries, especially Sweden, as a counterbalance. The unexpected results of the child evacuation, a Swedish initiative, had violated the good relations with Sweden. The motives of the Democratic Movement of Finnish People were much the same as those of the Patriotic Movement of Finnish People. Only the ideology was different. The Nordic political orientation was an obstacle to both parties. The position of the Democratic Movement of Finnish People was much better than that of the Patriotic Movement of Finnish People, because now one could clearly see the unexpected results, which included human tragedy for the many families who could not be re-united with their children despite their repeated requests. The Swedes questioned the figure given to the Finnish Parliament regarding the number of children permanently remaining in Sweden. This research agrees with the Swedes. In a calculation based on Swedish population registers, the number of these children is about 7 100. The reliability of this figure is increased by the fact that the child allowance programme began in Sweden in 1948. The prerequisite to have this allowance was that the child be in the Swedish population register. It was not necessary for the child to have Swedish nationality. The Finnish Parliament had false information about the number of Finnish children who remained in Sweden in 1942 and in 1950. There was no parliamentary control in Finland regarding child transports, because the decision was made by one cabinet member and speeches by MPs in the Finnish Parliament were censored, like all criticism regarding child transports to Sweden. In Great Britain parliamentary control worked better throughout the whole war, because the speeches regarding evacuation were not censored. At the beginning of the war certain members of the British Labour Party and the Welsh Nationalists were particularly outspoken about the scheme. Fagerholm does not discuss to any great extent the child transports in his memoirs. He does not evaluate the process and results as a whole. This research provides some possibilities for an evaluation of this sort. The Swedish medical reports give a clear picture of the physical condition of the Finnish children when arriving in Sweden. The transports actually revealed how bad the situation of the poorest children was. According to Titmuss, similar observations were made in Great Britain during the British evacuations. The child transports saved the lives of approximately 2 900 children. Most of these children were removed to Sweden to receive treatment for illnesses, but many among the healthy children were undernourished and some suffered from the effects of tuberculosis. The medical inspection in Finland was not thorough. If you compare the figure of 2 900 children saved and returned with the figure of about 7 100 children who remained permanently in Sweden, you may draw the conclusion that Finland as a country failed to benefit from the child transports, and that the whole operation was a political mistake with far-reaching consequenses. The basic goal of the operation was to save lives and have all the children return to Finland after the war. The difficulties with the repatriation of the children were mainly psychological. The level of child psychology in Finland at that time was low. One may question the report by Professor Martti Kaila regarding the adaptation of children to their families back in Finland. Anna Freud´s warnings concerning the difficulties that arise when child evacuees return are also valid in Finland. Freud viewed the emotional life of children in a way different from Kaila: the physical survival of a small child forces her to create strong emotional ties to the person who is looking after her. This, a characteristic of all small children, occurred with the Finnish children too, and it was something the political decision makers in Finland could not see during and after the war. It is a characteristic of all little children. Yet, such experiences were already evident during the Winter War. The best possible solution had been to limit the child transports only to children in need of medical treatment. Children from large and poor families had been helped by organising meals and by buying food from Denmark with Swedish money. Assisting Finland by all possible means should have been the basic goal of Fagerholm in September 1941, when the offer of child transports came from Sweden. Fagerholm felt gratitude towards the Swedes. The risks became clear to him only in 1943. The war children are today a rather scattered and diffuse group of people. Emotionally, part of these children remained in Sweden after the war. There is no clear collective memory, only individual memories; the collective memory of the war children has partly been shaped later through the activities of the war child associations. The main difference between the children evacuated in Finland (for example from Karelia to safer areas with their families) and the war children, who were sent abroad, is that the war children lack a shared story and experience with their families. They were outsiders . The whole matter is sensitive to many of such mothers and discussing the subject has often been avoided in families. The war-time censorship has continued in families through silence and avoidance and Finnish politicians and Finnish families had to face each other on this issue after the war. The lack of all-inclusive historical research has also prevented the formation of a collective awareness among war children returned to Finland or those remaining permanently abroad.. Knowledge of historical facts will help war-children by providing an opportunity to create an all-inclusive approach to the past. Personal experiences should be regarded as part of a large historical entity shadowed by war and where many political factors were at work in both Finland and Sweden. This means strengthening of the cognitive dimension discussed in Rüsen´s all-inclusive historical approach.
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The search engine log files have been used to gather direct user feedback on the relevancy of the documents presented in the results page. Typically the relative position of the clicks gathered from the log files is used a proxy for the direct user feedback. In this paper we identify reasons for the incompleteness of the relative position of clicks for deciphering the user preferences. Hence, we propose the use of time spent by the user in reading through the document as indicative of user preference for a document with respect to a query. Also, we identify the issues involved in using the time measure and propose means to address them.
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This thesis explores migration and the attractiveness of urban living in the Greater Helsinki region. The aim of the thesis is to explore the attractiveness of the city of Helsinki in terms of regional migration and to identify what characterizes migration to Helsinki. The study focuses in particular on housing, which is a key factor influencing migration decisions in the region. Other central themes in the study are housing policy and regional competition among municipalities. This study focuses solely on households moving within Finnish borders excluding international migration. Migration is examined by comparing in- and out-migration in Helsinki, as well as studying migration to the city s inner and outer areas. The primary research material in the study is a questionnaire data collected by the National Consumer Research Centre. In this thesis the data is used for studying migrants aged 25 45. The main research method is analyzing the data statistically using the SPSS software. Methods include frequency analysis, cross tabulation, factor analysis and descriptive analysis. Additionally, statistical data is used to complement the questionnaire data. The research results indicate that Helsinki s in- and out-migration differs both in terms of the type of households that migrate as well as in the reasons why they migrate. Furthermore, differences can also be detected between migration to the inner and outer parts of Helsinki. According to the research results, a household s current phase of life is crucial in determining where and why they move within the Greater Helsinki region. A household s set of values on the other hand, seems to have a lesser impact on migration within the region, even though households moving to Helsinki seem to value a somewhat more urban lifestyle than the ones moving out of the city. The research also shows a direct correlation between the values of migrants and their current phase of life. Decisions of migrating are heavily influenced by wider societal issues. In the Greater Helsinki region the labor and housing market appear to have a great influence on the direction of migration streams. According to the results, households move to and from Helsinki for different reasons. The primary reasons for moving to Helsinki are related to the city s diverse labor market and to the working careers of households. Issues related to urban living and an urban lifestyle seem to be relevant although not the main reason why people move to Helsinki. The research material indicates that Helsinki s urban environment is both a pull and a push factor affecting the decisions of migrants. The city attracts those seeking urban living, but on the contrary does not appeal to households seeking more space and wishing to live closer to nature. According to the research, Helsinki with its densely built urban environment mainly attracts singles and childless couples, whereas the city region s other municipalities are more attractive for families with children. Housing policy is one of the main reasons determining where people move within the Helsinki region. As for the city of Helsinki, improving the city s attractiveness seems to be closely linked to how well the city manages to execute its future housing policies and how well alternative living preferences can be taken into account in planning.
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Benzimidazole is toxic to silkworms due to its antagonistic action to purines. Cobalt and copper possess the capacity to reverse its toxicity because of their ability to form complexes with benzimidazole. For reasons unknown cobalt exerts a favourable effect in its free form rather than in the vitamin form on the insect growth.
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A study has been made of the stereochemistry of three of the four possible configurational isomers of trimethyl 1-methylcyclohexane-1,2,3-tricarboxylate. Two of the isomers undergo highly stereoselective methylation at the 3-position; the third cannot be methylated under similar conditions. Conformations have been suggested for these three isomers on the basis of n.m.r. results. It is thought that axial ester groups at the 1-position in the first two solvate the axial protons at the 3-position and facilitate their removal by trityl anion, while in the third, which has an axial methyl at the 1-position, the effect is not possible and the anion is not formed. The role of A(1.3) strain in causing the high stereoselectivity and position-specificity in the two cases where alkylation does take place and the reasons for slow inversion at the anion centre at position 3 in one of them are discussed.
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Havupuiden erikoismuotoja on käytetty koristekasveina jo vuosisatoja ympäri maailmaa. Niitä on lisätty pääsääntöisesti pistokkaista ja varttamalla. Suomessa kotimaisten metsäpuidemme erikois-muotoja on kartoitettu ja kerätty kokoelmiin järjestelmällisemmin 1960-luvulta alkaen. Taimisto-viljelijät, puutarhasuunnittelijat ja kotipuutarhurit ovat olleet enenevässä määrin kiinnostuneita näistä kotimaisista kestävistä havukasveista. Yli 90 prosenttia markkinoillamme olevista havukas-veista tuodaan ulkomailta, joten on selvää, että niiden talvenkestävyydessä on ongelmia. Tämän tutkimuksen tavoitteena oli selvittää kotimaisille erikoismuodoille sopivia lisäysmene-telmiä ja siten edistää kotimaisen havukasvituotannon mahdollisuuksia. Aineistona kokeissa oli kotimaisia erikoismuotoja metsäkuusesta (Picea abies (L.) Karsten) ja kotikatajasta (Juniperus communis L.), tavallisia metsäkuusia sekä kahdeksan ulkomaista havupuutaksonia. Lisäysmene-telmistä tutkittiin varttamista ja pistokaslisäystä ja kokeet suoritettiin Metsäntutkimuslaitoksen toimipaikoissa Lopen Haapastensyrjässä sekä Punkaharjulla. Varttamiskokeessa vertailtiin koti-maisen kuusen erikoismuotokloonien varttamisen onnistumista. Pistokaskokeissa tutkittiin geno-tyypin, emopuun iän, pistokasoksan sijainnin sekä hormonikäsittelyn vaikutusta havukasvien pis-tokkaiden juurtumiseen. Tavalliset metsäkuuset toimivat kontrolleina. Tutkimus osoitti, että varttaminen onnistui erinomaisesti kaikilla erikoismuotoklooneilla. Ovat-ko vartteet esteettisesti katsottuna koristekäyttöön sopivia, jää vielä seurattavaksi. Pistokaskokeis-sa havaittiin, että juveniilisuus vaikutti pistokkaiden juurtumiseen, mutta iäkkäistäkin puista lisää-minen onnistuu, kunhan genotyyppi on sopiva. Keskimäärin alaoksat juurtuivat paremmin kuin latvuksen yläosista otetut pistokasoksat, mutta vain yhdellä kloonilla ero oli tilastollisesti merkit-sevä. Hormonikäsittely heikensi selvästi kotimaisen kuusen ja katajan pistokkaiden juurtumista, mutta ulkomaisiin havupuulajeihin käsittelyllä ei ollut vaikutusta. Kotimaisen havukasvituotannon pohjaksi pitäisi tehdä kloonivalintaa, jossa koristearvon lisäksi otettaisiin huomioon myös kloonin lisättävyys. Taimien tuottaminen pistokkaista on selvästi edul-lisempaa kuin vartteiden tuottaminen, joskin varte kasvaa myyntikuntoon nopeammin kuin pisto-kastaimi. Pistokastaimi on kuitenkin omajuurinen ja stabiilimpi kasvutavaltaan kuin varte. Tämä korostuu etenkin kääpiömuotoja tuotettaessa.
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The method of preparation and physicochemical properties of peroxy titanium malonate, TiO2(OOC)2CH2·3H2O are given. The reasons for the poor complexing tendency of malonic acid are discussed. The nature of the bonds between titanium and the peroxy as well as malonate groups is assigned from spectrophotometric and infra-red absorption studies.
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We show, for sufficiently high temperatures and sufficiently weak majority-carrier binding energies, that the dominant radiative transition at an isoelectronic acceptor (donor) in p-type (n-type) material consists of the recombination of singly trapped minority carriers (bound by central-cell forces) with free majority carriers attracted by a Coulomb interaction. There are two reasons why the radiative recombination rate of the free-to-bound process is greater than the bound exciton process, which dominates at lower temperatures: (i) The population of free majority-carrier states greatly exceeds that of exciton states at higher temperatures, and (ii) the oscillator strength of the free-to-bound transition is greatly enhanced by the Coulomb attraction between the free carrier and the charged isoelectronic impurity. This enhancement is important for isoelectronic centers and is easily calculable from existing exciton models. We show that the free carrier attracted by a Coulomb interaction can be viewed as a continuum excited state of the bound exciton. When we apply the results of our calculations to the GaP(Zn, O) system, we find that the major part of the room-temperature luminescence from nearest-neighbor isoelectronic Zn-O complexes results from free-to-bound recombination and not exciton recombination as has been thought previously. Recent experiments on impulse excitation of luminescence in GaP(Zn, O) are reevaluated in the light of our calculations and are shown to be consistent with a strong free-to-bound transition. For deep isoelectronic centers with weakly bound majority carriers, we predict an overwhelming dominance of the free-to-bound process at 300°K.
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The method of preparation and physicochemical properties of peroxy titanium malonate, TiO2(OOC)2CH2·3H2O are given. The reasons for the poor complexing tendency of malonic acid are discussed. The nature of the bonds between titanium and the peroxy as well as malonate groups is assigned from spectrophotometric and infra-red absorption studies.
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This study addresses the issue of multilingualism in EU law. More specifically, it explores the implications of multilingualism for conceptualising legal certainty, a central principle of law both in domestic and EU legal systems. The main question addressed is how multilingualism and legal certainty may be reconciled in the EU legal system. The study begins with a discussion on the role of translation in drafting EU legislation and its implications for interpreting EU law at the European Court of Justice (ECJ). Uncertainty regarding the meaning of multilingual EU law and the interrelationship between multilingualism and ECJ methods of interpretation are explored. This analysis leads to questioning the importance of linguistic-semantic methods of interpretation, especially the role of comparing language versions for clarifying meaning and the ordinary meaning thesis, and to placing emphasis on other, especially the teleological, purpose-oriented method of interpretation. As regards the principle of legal certainty, the starting-point is a two-dimensional concept consisting of both formal and substantive elements; of predictability and acceptability. Formal legal certainty implies that laws and adjudication, in particular, must be predictable. Substantive legal certainty is related to rational acceptability of judicial decision-making placing emphasis on its acceptability to the legal community in question. Contrary to predictability that one might intuitively relate to linguistic-semantic methods of interpretation, the study suggests a new conception of legal certainty where purpose, telos, and other dynamic methods of interpretation are of particular significance for meaning construction in multilingual EU law. Accordingly, the importance of purposive, teleological interpretation as the standard doctrine of interpretation in a multilingual legal system is highlighted. The focus on rational, substantive acceptability results in emphasising discourse among legal actors among the EU legal community and stressing the need to give reasons in favour of proposed meaning in accordance with dynamic methods of interpretation including considerations related to purposes, aims, objectives and consequences. In this context, the role of ideal discourse situations and communicative action taking the form of interaction among the EU legal community in an ongoing dialogue especially in the preliminary ruling procedure is brought into focus. In order for this dialogue to function, it requires that the ECJ gives persuasive, convincing and acceptable reasons in justifying its decisions. This necessitates transparency, sincerity, and dialogue with the relevant audience.
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The purpose of this research was to study the bilingual class students attitudes toward schoolwork, studying in English and their attitudes toward ethnic diversity. Bilingualism has been shown to promote a person s cultural knowledge and to increase one s cultural tolerance. Also, it has been proven that young people are among the most receptive toward ethnic diversity. Students in bilingual classes have often lived abroad, travelled extensively, or have had contacts with different cultures through their parents work. This thesis seeks to clarify whether bilingualism has an effect on lower and upper graders intercultural competence. Also, it seeks to determine what the students think about their English language skills and what their abilities are to tolerate cultural differences. The research was carried out in one of Espoo Finland schools grades 4 to 9 in December 2008. One hundred fourteen (114) students participated in the research. Students answered the questions on a form where they were asked to submit their background information and answer which language they prefer in studying the school subjects. Students were also asked to choose from 18 pictures with ethnically different persons, telling which ones could be their friends and which ones they wished not to meet, as well as stating the reasons why. Also, the students answered to Likert-scale questions concerning their English studies and interculturalism. The data has been processed with qualitative and quantitative methods. The results show that the study language is not significant. Most of the students experienced studying in a bilingual class as a positive thing, and thought highly about their English skills. The students positive attitudes toward ethnic diversity and intercultural sensitivity were present in their answers. Tolerance and intercultural competence was especially noticeable in the written explanations by the older students.
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Mass spectrometry (MS) became a standard tool for identifying metabolites in biological tissues, and metabolomics is slowly acknowledged as a legitimate research discipline for characterizing biological conditions. The computational analyses of metabolomics, however, lag behind compared with the rapid advances in analytical aspects for two reasons. First is the lack of standardized data repository for mass spectra: each research institution is flooded with gigabytes of mass-spectral data from its own analytical groups and cannot host a world-class repository for mass spectra. The second reason is the lack of informatics experts that are fully experienced with spectral analyses. The two barriers must be overcome to establish a publicly free data server for MS analysis in metabolomics as does GenBank in genomics and UniProt in proteomics. The workshop brought together bioinformaticians working on mass spectral analyses in Finland and Japan with the goal to establish a consortium to freely exchange and publicize mass spectra of metabolites measured on various platforms computational tools to analyze spectra spectral knowledge that are computationally predicted from standardized data. This book contains the abstracts of the presentations given in the workshop. The programme of the workshop consisted of oral presentations from Japan and Finland, invited lectures from Steffen Neumann (Leibniz Institute of Plant Biochemistry), Matej Oresic (VTT), Merja Penttila (VTT) and Nicola Zamboni (ETH Zurich) as well as free form discussion among the participants. The event was funded by Academy of Finland (grants 139203 and 118653), Japan Society for the Promotion of Science (JSPS Japan-Finland Bilateral Semi- nar Program 2010) and Department of Computer Science University of Helsinki. We would like to thank all the people contributing to the technical pro- gramme and the sponsors for making the workshop possible. Helsinki, October 2010 Masanori Arita, Markus Heinonen and Juho Rousu
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The question at issue in this dissertation is the epistemic role played by ecological generalizations and models. I investigate and analyze such properties of generalizations as lawlikeness, invariance, and stability, and I ask which of these properties are relevant in the context of scientific explanations. I will claim that there are generalizable and reliable causal explanations in ecology by generalizations, which are invariant and stable. An invariant generalization continues to hold or be valid under a special change called an intervention that changes the value of its variables. Whether a generalization remains invariant during its interventions is the criterion that determines whether it is explanatory. A generalization can be invariant and explanatory regardless of its lawlike status. Stability deals with a generality that has to do with holding of a generalization in possible background conditions. The more stable a generalization, the less dependent it is on background conditions to remain true. Although it is invariance rather than stability of generalizations that furnishes us with explanatory generalizations, there is an important function that stability has in this context of explanations, namely, stability furnishes us with extrapolability and reliability of scientific explanations. I also discuss non-empirical investigations of models that I call robustness and sensitivity analyses. I call sensitivity analyses investigations in which one model is studied with regard to its stability conditions by making changes and variations to the values of the model s parameters. As a general definition of robustness analyses I propose investigations of variations in modeling assumptions of different models of the same phenomenon in which the focus is on whether they produce similar or convergent results or not. Robustness and sensitivity analyses are powerful tools for studying the conditions and assumptions where models break down and they are especially powerful in pointing out reasons as to why they do this. They show which conditions or assumptions the results of models depend on. Key words: ecology, generalizations, invariance, lawlikeness, philosophy of science, robustness, explanation, models, stability