Seismic Tomography and Earthquake Mechanism Beneath the Central Fennoscandian Shield

The aim of this thesis was to study the seismic tomography structure of the earth s crust together with earthquake distribution and mechanism beneath the central Fennoscandian Shield, mainly in southern and central Finland. The earthquake foci and some fault plane solutions are correlated with 3-D images of the velocity tomography. The results are discussed in relation to the stress field of the Shield and with other geophysical, e.g. geomagnetic, gravimetric, tectonic, and anisotropy studies of the Shield. The earthquake data of the Fennoscandian Shield has been extracted from the Nordic earthquake parameter data base which was founded at the time of inception of the earthquake catalogue for northern Europe. Eight earlier earthquake source mechanisms are included in a pilot study on creating a novel technique for calculating an earthquake fault plane solution. Altogether, eleven source mechanisms of shallow, weak earthquakes are related in the 3-D tomography model to trace stresses of the crust in southern and central Finland. The earthquakes in the eastern part of the Fennoscandian Shield represent low-active, intraplate seismicity. Earthquake mechanisms with NW-SE oriented horizontal compression confirm that the dominant stress field originates from the ridge-push force in the North Atlantic Ocean. Earthquakes accumulate in coastal areas, in intersections of tectonic lineaments, in main fault zones or are bordered by fault lines. The majority of Fennoscandian earthquakes concentrate on the south-western Shield in southern Norway and Sweden. Onwards, epicentres spread via the ridge of the Shield along the west-coast of the Gulf of Bothnia northwards along the Tornio River - Finnmark fault system to the Barents Sea, and branch out north-eastwards via the Kuusamo region to the White Sea Kola Peninsula faults. The local seismic tomographic method was applied to find the terrane distribution within the central parts of the Shield the Svecofennian Orogen. From 300 local explosions a total of 19765 crustal Pg- and Sg-wave arrival times were inverted to create independent 3-D Vp and Vs tomographic models, from which the Vp/Vs ratio was calculated. The 3-D structure of the crust is presented as a P-wave and for the first time as an S-wave velocity model, and also as a Vp/Vs-ratio model of the SVEKALAPKO area that covers 700x800 km2 in southern and central Finland. Also, some P-wave Moho-reflection data was interpolated to image the relief of the crust-mantle boundary (i.e. Moho). In the tomography model, the seismic velocities vary smoothly. The lateral variations are larger for Vp (dVp =0.7 km/s) than for Vs (dVs =0.4 km/s). The Vp/Vs ratio varies spatially more distinctly than P- and S-wave velocities, usually from 1.70 to 1.74 in the upper crust and from 1.72 to 1.78 in the lower crust. Schist belts and their continuations at depth are associated with lower velocities and lower Vp/Vs ratios than in the granitoid areas. The tomography modelling suggests that the Svecofennian Orogen was accreted from crustal blocks ranging in size from 100x100 km2 to 200x200 km2 in cross-sectional area. The intervening sedimentary belts have ca. 0.2 km/s lower P- and S-wave velocities and ca. 0.04 lower Vp/Vs ratios. Thus, the tomographic model supports the concept that the thick Svecofennian crust was accreted from several crustal terranes, some hidden, and that the crust was later modified by intra- and underplating. In conclusion, as a novel approach the earthquake focal mechanism and focal depth distribution is discussed in relation to the 3-D tomography model. The schist belts and the transformation zones between the high- and low-velocity anomaly blocks are characterized by deeper earthquakes than the granitoid areas where shallow events dominate. Although only a few focal mechanisms were solved for southern Finland, there is a trend towards strike-slip and oblique strike-slip movements inside schist areas. The normal dip-slip type earthquakes are typical in the seismically active Kuusamo district in the NE edge of the SVEKALAPKO area, where the Archean crust is ca. 15-20 km thinner than the Proterozoic Svecofennian crust. Two near vertical dip-slip mechanism earthquakes occurred in the NE-SW junction between the Central Finland Granitoid Complex and the Vyborg rapakivi batholith, where high Vp/Vs-ratio deep-set intrusion splits the southern Finland schist belt into two parts in the tomography model.

Neutral-point balancing of neutral-point-clamped three-level inverter with a front end switched rectifier DC source for the full modulationn range

A switched rectifier DC voltage source three-level neutral-point-clamped (NPC) converter topology is proposed here to alleviate the inverter from capacitor voltage balancing in three-level drive systems. The proposed configuration requires only one DC link with a voltage of half of that needed in a conventional NPC inverter. To obtain a rated DC link voltage, the rectifier DC source is alternately connected in parallel to one of the two series capacitors using two switches and two diodes with device voltage ratings of half the total DC bus voltage. The frequency at which the voltage source is switched is independent of the inverter and will not affect its operation since the switched voltage source in this configuration balances the capacitors automatically. The proposed configuration can also be used as a conventional two-level inverter in the lower modulation index range, thereby increasing the reliability of the drivesystem. A space-vector-based PWM scheme is used to verify this proposed topology on a laboratory system.

Fertility in Namibia : Changes in fertility levels in North-Central Namibia 1960-2001, including an assessment of the impact of HIV

The aim of this study was to estimate the development of fertility in North-Central Namibia, former Ovamboland, from 1960 to 2001. Special attention was given to the onset of fertility decline and to the impact of the HIV epidemic on fertility. An additional aim was to introduce parish registers as a source of data for fertility research in Africa. Data used consisted of parish registers from Evangelical Lutheran congregations, the 1991 and 2001 Population and Housing Censuses, the 1992 and 2000 Namibia Demographic and Health Surveys, and the HIV sentinel surveillances of 1992-2004. Both period and cohort fertility were analysed. The P/F ratio method was used when analysing census data. The impact of HIV infection on fertility was estimated indirectly by comparing the fertility histories of women who died at an age of less than 50 years with the fertility of other women. The impact of the HIV epidemic on fertility was assessed both among infected women and in the general population. Fertility in the study population began to decline in 1980. The decline was rapid during the 1980s, levelled off in the early 1990s at the end of war of independence and then continued to decline until the end of the study period. According to parish registers, total fertility was 6.4 in the 1960s and 6.5 in the 1970s, and declined to 5.1 in the 1980s and 4.2 in the 1990s. Adjustment of these total fertility rates to correspond to levels of fertility based on data from the 1991 and 2001 censuses resulted in total fertility declining from 7.6 in 1960-79 to 6.0 in 1980-89, and to 4.9 in 1990-99. The decline was associated with increased age at first marriage, declining marital fertility and increasing premarital fertility. Fertility among adolescents increased, whereas the fertility of women in all other age groups declined. During the 1980s, the war of independence contributed to declining fertility through spousal separation and delayed marriages. Contraception has been employed in the study region since the 1980s, but in the early 1990s, use of contraceptives was still so limited that fertility was higher in North-Central Namibia than in other regions of the country. In the 1990s, fertility decline was largely a result of the increased prevalence of contraception. HIV prevalence among pregnant women increased from 4% in 1992 to 25% in 2001. In 2001, total fertility among HIV-infected women (3.7) was lower than that among other women (4.8), resulting in total fertility of 4.4 among the general population in 2001. The HIV epidemic explained more than a quarter of the decline in total fertility at population level during most of the 1990s. The HIV epidemic also reduced the number of children born by reducing the number of potential mothers. In the future, HIV will have an extensive influence on both the size and age structure of the Namibian population. Although HIV influences demographic development through both fertility and mortality, the effect through changes in fertility will be smaller than the effect through mortality. In the study region, as in some other regions of southern Africa, a new type of demographic transition is under way, one in which population growth stagnates or even reverses because of the combined effects of declining fertility and increasing mortality, both of which are consequences of the HIV pandemic.

A Success Story or a Failure? : Representing the European Integration in the Curricula and Textbooks of Five Countries

The economic, political and social face of Europe has been changing rapidly in the past decades. These changes are unique in the history of Europe, but not without challenges for the nation states. The support for the European integration varies among the countries. In order to understand why certain developments or changes are perceived as threatening or as desired by different member countries, we must consider the social representations of the European integration on the national level: how the EU is represented to its citizens in media and in educational systems, particularly in the curricula and textbooks. The current study is concerned with the social representations of the European integration in the curricula and school textbooks in five European countries: France, Britain, Germany, Finland and Sweden. Besides that, the first volume of the common Franco-German history textbook was analyzed, since it has been seen as a model for a common European history textbook. As the collective representations, values and identities are dominantly mediated and imposed through media and educational systems, the national curricula and textbooks make an interesting starting point for the study of the European integration and of national and European identities. The social representations theory provides a comprehensive framework for the study of the European integration. By analyzing the curricula and history and civics textbooks of major educational publishers, the study aimed to demonstrate what is written on the European integration and how it is portrayed how the European integration is understood, made familiar and concretized in the educational context in the five European countries. To grasp the phenomenon of the European integration in the textbooks in its entirety, it was investigated from various perspectives. The two analysis methods of content analysis, the automatic analysis with ALCESTE and a more qualitative theory-driven content analysis, were carried out to give a more vivid and multifaceted picture of the object of the research. The analysis of the text was complemented with the analysis of visual material. Drawing on quantitative and qualitative methods, the contents, processes, visual images, transformations and structures of the social representations of European integration, as well as the communicative styles of the textbooks were examined. This study showed the divergent social representations of the European integration, anchored in the nation states, in the five member countries of the European Union. The social representations were constructed around different central core elements: French Europe in the French textbooks, Ambivalent Europe in the British textbooks, Influential and Unifying EU in the German textbooks, Enabling and Threatening EU in the Finnish textbooks, Sceptical EU in the Swedish textbooks and EU as a World Model in the Franco-German textbook. Some elements of the representations were shared by all countries such as peace and economic aspects of the European cooperation, whereas other elements of representations were found more frequently in some countries than in others, such as ideological, threatening or social components of the phenomenon European integration. The study also demonstrated the linkage between social representations of the EU and national and European identities. The findings of this study are applicable to the study of the European integration, to the study of education, as well as to the social representation theory.

Kansallisen konsensuskulttuurin jäljillä : Globalisaatioajan Suomi Helsingin Sanomissa

The dissertation analyzes Finnish consensual culture in public discussion and journalism in Helsingin Sanomat (HS). The consensual Finnish political culture has evolved and persisted over a long period of time and it has been affected by historical circumstances as well as the dynamics of political and journalistic structures and actors. A historical chronology is drawn in the study regarding the nature and development of consensus culture in 20th century Finland. This political culture is traced by looking at public discussion on globalization at the turn of the millennium. Globalization as a concept has been contested and various societal actors have given different meanings to it. This research looks at how the globalization discussion in HS during the years 1992-2004 constructs consensus. Helsingin Sanomat (and its predecessor Päivälehti) has been an important actor in Finnish journalism and the public sphere almost since its founding 120 years ago. The history of the paper is tightly connected to Finland s general political history and history of the public sphere. Moreover, the paper s connections to the societal elite have always been close. The central question in this research was to see how the globalization discussion in HS evolved in relation to consensus as well as legitimate controversies. As a result it is stated that the globalization question has clearly divided the Finnish societal actors. The most powerful societal elites (government, most civil servants, corporate sector) had a profile of being pro globalization. They communicated their globalization strategy as a national, unified way of thinking. Other elites which have been losing their influence (the president, labor union, part of members of parliament), as well as civil society actors tried to bring forward conflicting views in relation to globalization. The paper did give some room to these elements, but on the other hand it also tried to keep up the consensual discussion culture especially in the editorial section. In line with its traditions Helsingin Sanomat strived to create national unity. At the same time it did not give adequate attention to the changes brought about by globalization to the positions and roles of various elites and civil society actors. In this discussion HS seemed more like a medium of the state than as a critical and independent actor. Journalism has an important role in upholding and also reviving the Finnish political culture and public discussion. From this point of view it is problematic if the area of so called legitimate controversy in broad societal questions like globalization becomes very limited. As the Finnish elites are small and there is no considerable competition between them, journalism should actively bring up controversial issues. This task becomes complicated, however, if the elite circles are closed up and no initiatives come from their ranks. Political decision making as well as democracy can suffer, if issues are not brought to the public agenda.

Suitability of a point-contact SAW-based stiffness transducer for biomedical applications

Methods of diagnosis in Biomedical applications can be broadly divided into contact and non-contact based methods. So far, ultrasound based methods have been found to be most favorable for non-contact, non-invasive diagnosis, especially in the case of tissue stiffness analysis. We report here, the fabrication and characterization details of a new contact based transducer system for qualitative determination of the stiffnesses of non-piezoelectric substrates using the phenomenon of Surface Acoustic Waves (SAW). Preliminary trials to study the functionality of this system were carried out on various metallic and non-metallic substrates, and the results were found to be satisfactory. To confirm the suitability of this system for biomedical applications, similar trials have been conducted on tissue mimicking phantoms with varying degrees of stiffness.

Unsteady mixed convection on the stagnation-point flow adjacent to a vertical plate with a magnetic field

An analysis is performed to study the unsteady combined forced and free convection flow (mixed convection flow) of a viscous incompressible electrically conducting fluid in the vicinity of an axisymmetric stagnation point adjacent to a heated vertical surface. The unsteadiness in the flow and temperature fields is due to the free stream velocity, which varies arbitrarily with time. Both constant wall temperature and constant heat flux conditions are considered in this analysis. By using suitable transformations, the Navier-Stokes and energy equations with four independent variables (x, y, z, t) are reduced to a system of partial differential equations with two independent variables (eta, tau). These transformations also uncouple the momentum and energy equations resulting in a primary axisymmetric flow, in an energy equation dependent on the primary flow and in a buoyancy-induced secondary flow dependent on both primary flow and energy. The resulting system of partial differential equations has been solved numerically by using both implicit finite-difference scheme and differential-difference method. An interesting result is that for a decelerating free stream velocity, flow reversal occurs in the primary flow after certain instant of time and the magnetic field delays or prevents the flow reversal. The surface heat transfer and the surface shear stress in the primary flow increase with the magnetic field, but the surface shear stress in the buoyancy-induced secondary flow decreases. Further the heat transfer increases with the Prandtl number, but the surface shear stress in the secondary flow decreases.

Social Networks and Everyday Practices in Russia

My doctoral dissertation in sociology and Russian studies, Social Networks and Everyday Practices in Russia, employs a "micro" or "grassroots" perspective on the transition. The study is a collection of articles detailing social networks in five different contexts. The first article examines Russian birthdays from a network perspective. The second takes a look at health care to see whether networks have become obsolete in a sector that is still overwhelmingly public, but increasingly being monetarised. The third article investigates neighbourhood relations. The fourth details relationships at work, particularly from the vantage point of internal migration. The fifth explores housing and the role of networks and money both in the Soviet and post-Soviet era. The study is based on qualitative social network and interview data gathered among three groups, teachers, doctors and factory workers, in St. Petersburg during 1993-2000. Methodologically it builds on a qualitative social network approach. The study adds a critical element to the discussion on networks in post-socialism. A considerable consensus exists that social networks were vital in state socialist societies and were used to bypass various difficulties caused by endemic shortages and bureaucratic rigidities, but a more debated issue has been their role in post-socialism. Some scholars have argued that the importance of networks has been dramatically reduced in the new market economy, whereas others have stressed their continuing importance. If a common denominator in both has been a focus on networks in relation to the past, a more overlooked aspect has been the question of inequality. To what extent is access to networks unequally distributed? What are the limits and consequences of networks, for those who have access, those outside networks or society at large? My study provides some evidence about inequalities. It shows that some groups are privileged over others, for instance, middle-class people in informal access to health care. Moreover, analysing the formation of networks sheds additional light on inequalities, as it highlights the importance of migration as a mechanism of inequality, for example. The five articles focus on how networks are actually used in everyday life. The article on health care, for instance, shows that personal connections are still important and popular in post-Soviet Russia, despite the growing importance of money and the emergence of "fee for service" medicine. Fifteen of twenty teachers were involved in informal medical exchange during a two-week study period, so that they used their networks to bypass the formal market mechanisms or official procedures. Medicines were obtained through personal connections because some were unavailable at local pharmacies or because these connections could provide medicines for a cheaper price or even for free. The article on neighbours shows that "mutual help" was the central feature of neighbouring, so that the exchange of goods, services and information covered almost half the contacts with neighbours reported. Neighbours did not provide merely small-scale help but were often exchange partners because they possessed important professional qualities, had access to workplace resources, or knew somebody useful. The article on the Russian work collective details workplace-related relationships in a tractor factory and shows that interaction with and assistance from one's co-workers remains important. The most interesting finding was that co-workers were even more important to those who had migrated to the city than to those who were born there, which is explained by the specifics of Soviet migration. As a result, the workplace heavily influenced or absorbed contexts for the worker migrants to establish relationships whereas many meeting-places commonly available in Western countries were largely absent or at least did not function as trusted public meeting places to initiate relationships. More results are to be found from my dissertation: Anna-Maria Salmi: Social Networks and Everyday Practices in Russia, Kikimora Publications, 2006, see www.kikimora-publications.com.

Trust and Collectives

"Trust and Collectives" is a compilation of articles: (I) "On Rational Trust" (in Meggle, G. (ed.) Social Facts & Collective Intentionality, Dr. Hänsel-Hohenhausen AG (currently Ontos), 2002), (II) "Simulating Rational Social Normative Trust, Predictive Trust, and Predictive Reliance Between Agents" (M.Tuomela and S. Hofmann, Ethics and Information Technology 5, 2003), (III) "A Collective's Trust in a Collective's action" (Protosociology, 18-19, 2003), and (IV) "Cooperation and Trust in Group Contexts" (R. Tuomela and M.Tuomela, Mind and Society 4/1, 2005 ). The articles are tied together by an introduction that dwells deeply on the topic of trust. (I) presents a somewhat general version of (RSNTR) and some basic arguments. (II) offers an application of (RSNTR) for a computer simulation of trust.(III) applies (RSNTR) to Raimo Tuomela's "we-mode"collectives (i.e. The Philosophy of Social Practices, Cambridge University Press, 2002). (IV) analyzes cooperation and trust in the context of acting as a member of a collective. Thus, (IV) elaborates on the topic of collective agency in (III) and puts the trust account (RSNTR) to work in a framework of cooperation. The central aim of this work is to construct a well-argued conceptual and theoretical account of rational trust, viz. a person's subjectively rational trust in another person vis-à-vis his performance of an action, seen from a first-person point of view. The main method is conceptual and theoretical analysis understood along the lines of reflective equilibrium. The account of rational social normative trust (RSNTR), which is argued and defended against other views, is the result of the quest. The introduction stands on its own legs as an argued presentation of an analysis of the concept of rational trust and an analysis of trust itself (RSNTR). It is claimed that (RSNTR) is "genuine" trust and embedded in a relationship of mutual respect for the rights of the other party. This relationship is the growing site for trust, a causal and conceptual ground, but it is not taken as a reason for trusting (viz. predictive "trust"). Relevant themes such as risk, decision, rationality, control, and cooperation are discussed and the topics of the articles are briefly presented. In this work it is argued that genuine trust is to be kept apart from predictive "trust." When we trust a person vis-à-vis his future action that concerns ourselves on the basis of his personal traits and/or features of the specific situation we have a prediction-like attitude. Genuine trust develops in a relationship of mutual respect for the mutual rights of the other party. Such a relationship is formed through interaction where the parties gradually find harmony concerning "the rules of the game." The trust account stands as a contribution to philosophical research on central social notions and it could be used as a theoretical model in social psychology, economical and political science where interaction between persons and groups are in focus. The analysis could also serve as a model for a trust component in computer simulation of human action. In the context of everyday life the account clarifies the difference between predictive "trust" and genuine trust. There are no fast shortcuts to trust. Experiences of mutual respect for mutual rights cannot be had unless there is respect.

Knowledge through Discussion : An Interpretation of Epistemology in Plato's Meno

According to Meno s paradox we cannot inquire into what we do not know because we do not know what we are inquiring into. There are many ways to interpret the paradox but the central issue about our ability to reach truth is a profound one. In the dialogue Meno, Plato presents the paradox and an outline of a solution which enables us to reach knowledge (epistēmē) through philosophical discussion. During the last century Meno has often been considered transitional between Socratic thinking and Plato s own philosophy, and thus the dialogue has not been adequately interpreted as an integrated whole. Therefore the distinctive epistemology of the dialogue has not gained due notice. In this thesis the dialogue is analysed as an integrated whole and the philosophical interpretation also takes into account its dramatic features. The thesis emphasises the role of language and definitions in acquiring knowledge. Among the results concerning these subjects is a new interpretation of Socrates s defintion of shape (schēma). The theory of anamnēsis all learning is recollection in the Meno is argued to answer the paradox philosophically although Plato s presentation also contains playful and ironic elements. The background of the way Plato presents his case is that he appreciated the fact that no argument can plausibly demonstrate that argumentation is able to reach truth. In the Meno, Plato makes the earliest explicit distinction between knowledge and true belief in the history of Western philosophy. He also gives a definition of knowledge which is the basis of the so called classical definition of knowledge as justified true belief. In the Meno, true beliefs become knowledge when someone ties them down by reasoning about the explanation. The analysis of the epistemology of the dialogue from this perspective gives an interpretation which integrates the central concepts of the epistemology in the dialogue elenchos, anamnēsis and hypothetical inquiry into a unified whole which contains a plausible argument according to which the ignorant can reach knowledge through discussion. The conception that emerges by such an analysis is interesting both from the point of view of current interests and that of the history of philosophy. The method of knowledge acquisition in the Meno can, for example, be seen as a predecessor of modern scientific methods. The Meno is the earliest Greek mathematical text that has survived in its original form. The analysis presented in the thesis of the geometric passages in the dialogue provides new results both concerning Socrates s geometry lesson with the slave and the example presenting the hypothetical method. Concerning the latter, a new interpretation is presented. Keywords: anamnēsis, epistēmē, knowledge, Meno s paradox, Plato

Diffraction and Total Cross-Section at the Tevatron and the LHC

At the Tevatron, the total p_bar-p cross-section has been measured by CDF at 546 GeV and 1.8 TeV, and by E710/E811 at 1.8 TeV. The two results at 1.8 TeV disagree by 2.6 standard deviations, introducing big uncertainties into extrapolations to higher energies. At the LHC, the TOTEM collaboration is preparing to resolve the ambiguity by measuring the total p-p cross-section with a precision of about 1 %. Like at the Tevatron experiments, the luminosity-independent method based on the Optical Theorem will be used. The Tevatron experiments have also performed a vast range of studies about soft and hard diffractive events, partly with antiproton tagging by Roman Pots, partly with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will carry out their diffractive programme with an unprecedented rapidity coverage and Roman Pot spectrometers on both sides of the interaction point. The physics menu comprises detailed studies of soft diffractive differential cross-sections, diffractive structure functions, rapidity gap survival and exclusive central production by Double Pomeron Exchange.

Alppihiihdon alkutaival : Pujottelu- ja tunturihiihto Suomessa 1920-luvulta 1960-luvulle

The object of study in this thesis is Finnish skiing culture and Alpine skiing in particular from the point of view of ethnology. The objective is to clarify how, when, why and by what routes Alpine skiing found its way to Finland. What other phenomena did it bring forth? The objective is essentially linked to the diffusion of modern sports culture to Finland. The introduction of Alpine skiing to Finland took place at a time when skiing culture was changing: flat terrain skiing was abandoned in favour of cross-country skiing in the early decades of the 20th century, and new techniques and equipment made skiing a much more versatile sport. The time span of the study starts from the late 19th century and ends in the mid-20th century. The spatial focus is in Finland. People and communities formed through their actions are core elements in the study of sports and physical activity. Organizations tend to raise themselves into influential actors in the field of physical culture even if active individuals work in their background. Original archive documents and publications of sports organizations are central source material for this thesis, complemented by newspapers and sports magazines as well as photographs and films on early Alpine skiing in Finland. Ever since their beginning in the late 19th century skiing races in Finland had mostly taken place on flat terrain or sea ice. Skiing in broken cross-country terrain made its breakthrough in the 1920 s, at a time when modern skiing techniques were introduced in instruction manuals. In the late 1920 s the Finnish Women s Physical Education Association (SNLL) developed unconventional forms of pedagogical skiing instruction. They abandoned traditional Finnish flat terrain skiing and boldly looked for influences abroad, which caused friction between the leaders of the women s sports movement and the (male) leaders of the central skiing organization. SNLL was instrumental in launching winter tourism in Finnish Lapland in 1933. The Finnish Tourism Society, the State Railways and sports organizations worked in close co-operation to instigate a boom in tourism, which culminated in the inauguration of a tourist hotel at Pallastunturi hill in the winter of 1938. Following a Swedish model, fell-skiing was developed as a domestic counterpart to Alpine skiing as practiced in Central Europe. The first Finnish skiing resorts were built at sites of major cross-country skiing races. Inspired by the slope at Bad Grankulla health spa, the first slalom skiing races and fell-skiing, slalom enthusiasts began to look for purpose-built sites to practice turn technique. At first they would train in natural slopes but in the late 1930 s new slopes were cleared for slalom races and recreational skiing. The building of slopes and ski lifts and the emergence of organized slalom racing competitions gradually separated Alpine skiing from the old fell-skiing. After the Second World War fell-skiing was transformed into ski trekking on marked courses. At the same time Alpine skiing also parted ways with cross-country skiing to become a sport of its own. In the 1940 s and 1950 s Finnish Alpine skiing was almost exclusively a competitive sport. The specificity of Alpine skiing was enhanced by rapid development of equipment: the new skis, bindings and shoes could only be used going downhill.

Comparative analysis of thermophilic and mesophilic proteins using Protein Energy Networks

Background: Thermophilic proteins sustain themselves and function at higher temperatures. Despite their structural and functional similarities with their mesophilic homologues, they show enhanced stability. Various comparative studies at genomic, protein sequence and structure levels, and experimental works highlight the different factors and dominant interacting forces contributing to this increased stability. Methods: In this comparative structure based study, we have used interaction energies between amino acids, to generate structure networks called as Protein Energy Networks (PENs). These PENs are used to compute network, sub-graph, and node specific parameters. These parameters are then compared between the thermophile-mesophile homologues. Results: The results show an increased number of clusters and low energy cliques in thermophiles as the main contributing factors for their enhanced stability. Further more, we see an increase in the number of hubs in thermophiles. We also observe no community of electrostatic cliques forming in PENs. Conclusion: In this study we were able to take an energy based network approach, to identify the factors responsible for enhanced stability of thermophiles, by comparative analysis. We were able to point out that the sub-graph parameters are the prominent contributing factors. The thermophiles have a better-packed hydrophobic core. We have also discussed how thermophiles, although increasing stability through higher connectivity retains conformational flexibility, from a cliques and communities perspective.

Comparative analysis of thermophilic and mesophilic proteins using Protein Energy Networks

Background: Thermophilic proteins sustain themselves and function at higher temperatures. Despite their structural and functional similarities with their mesophilic homologues, they show enhanced stability. Various comparative studies at genomic, protein sequence and structure levels, and experimental works highlight the different factors and dominant interacting forces contributing to this increased stability. Methods: In this comparative structure based study, we have used interaction energies between amino acids, to generate structure networks called as Protein Energy Networks (PENs). These PENs are used to compute network, sub-graph, and node specific parameters. These parameters are then compared between the thermophile-mesophile homologues. Results: The results show an increased number of clusters and low energy cliques in thermophiles as the main contributing factors for their enhanced stability. Further more, we see an increase in the number of hubs in thermophiles. We also observe no community of electrostatic cliques forming in PENs. Conclusion: In this study we were able to take an energy based network approach, to identify the factors responsible for enhanced stability of thermophiles, by comparative analysis. We were able to point out that the sub-graph parameters are the prominent contributing factors. The thermophiles have a better-packed hydrophobic core. We have also discussed how thermophiles, although increasing stability through higher connectivity retains conformational flexibility, from a cliques and communities perspective.