γ-Y2Si2O7, a machinable silicate ceramic: Mechanical properties and machinability

In this paper, the mechanical properties of bulk single-phase γ-Y2Si2O7 ceramic are reported. γ-Y2Si2O7 exhibits low shear modulus, excellent damage tolerance, and thus has a good machinability ready for metal working tools. To understand the underlying mechanism of machinability, drilling test, Hertzian contact test, and density functional theory (DFT) calculation are employed. Hertzian contact test demonstrates that γ-Y2Si2O7 is a "quasi-plastic" ceramic and the intrinsically weak interfaces contribute to its machinability. Crystal structure characteristics and DFT calculations of γ-Y2Si2O7 suggest that some weakly bonded planes, which involve Y-O bonds that can be easily broken, are the sources of the low shear deformation resistance and good machinability.

A note on the Hadwiger number of circular arc graphs

The intention of this note is to motivate the researchers to study Hadwiger's conjecture for circular arc graphs. Let η(G) denote the largest clique minor of a graph G, and let χ(G) denote its chromatic number. Hadwiger's conjecture states that η(G)greater-or-equal, slantedχ(G) and is one of the most important and difficult open problems in graph theory. From the point of view of researchers who are sceptical of the validity of the conjecture, it is interesting to study the conjecture for graph classes where η(G) is guaranteed not to grow too fast with respect to χ(G), since such classes of graphs are indeed a reasonable place to look for possible counterexamples. We show that in any circular arc graph G, η(G)less-than-or-equals, slant2χ(G)−1, and there is a family with equality. So, it makes sense to study Hadwiger's conjecture for this family.

DMT of Multi-hop Cooperative Networks-Part I: K-Parallel-Path Networks

We consider single-source, single-sink multi-hop relay networks, with slow-fading Rayleigh fading links and single-antenna relay nodes operating under the half-duplex constraint. While two hop relay networks have been studied in great detail in terms of the diversity-multiplexing tradeoff (DMT), few results are available for more general networks. In this two-part paper, we identify two families of networks that are multi-hop generalizations of the two hop network: K-Parallel-Path (KPP) networks and Layered networks. In the first part, we initially consider KPP networks, which can be viewed as the union of K node-disjoint parallel paths, each of length > 1. The results are then generalized to KPP(I) networks, which permit interference between paths and to KPP(D) networks, which possess a direct link from source to sink. We characterize the optimal DMT of KPP(D) networks with K >= 4, and KPP(I) networks with K >= 3. Along the way, we derive lower bounds for the DMT of triangular channel matrices, which are useful in DMT computation of various protocols. As a special case, the DMT of two-hop relay network without direct link is obtained. Two key implications of the results in the two-part paper are that the half-duplex constraint does not necessarily entail rate loss by a factor of two, as previously believed and that, simple AF protocols are often sufficient to attain the best possible DMT.

Heritability of the network architecture of intrinsic brain functional connectivity

The brain's functional network exhibits many features facilitating functional specialization, integration, and robustness to attack. Using graph theory to characterize brain networks, studies demonstrate their small-world, modular, and "rich-club" properties, with deviations reported in many common neuropathological conditions. Here we estimate the heritability of five widely used graph theoretical metrics (mean clustering coefficient (γ), modularity (Q), rich-club coefficient (ϕnorm), global efficiency (λ), small-worldness (σ)) over a range of connection densities (k=5-25%) in a large cohort of twins (N=592, 84 MZ and 89 DZ twin pairs, 246 single twins, age 23±2.5). We also considered the effects of global signal regression (GSR). We found that the graph metrics were moderately influenced by genetic factors h2 (γ=47-59%, Q=38-59%, ϕnorm=0-29%, λ=52-64%, σ=51-59%) at lower connection densities (≤15%), and when global signal regression was implemented, heritability estimates decreased substantially h2 (γ=0-26%, Q=0-28%, ϕnorm=0%, λ=23-30%, σ=0-27%). Distinct network features were phenotypically correlated (|r|=0.15-0.81), and γ, Q, and λ were found to be influenced by overlapping genetic factors. Our findings suggest that these metrics may be potential endophenotypes for psychiatric disease and suitable for genetic association studies, but that genetic effects must be interpreted with respect to methodological choices.

Conformal Field Theory Methods for Variants of Schramm-Loewner Evolutions

This thesis consists of an introduction, four research articles and an appendix. The thesis studies relations between two different approaches to continuum limit of models of two dimensional statistical mechanics at criticality. The approach of conformal field theory (CFT) could be thought of as the algebraic classification of some basic objects in these models. It has been succesfully used by physicists since 1980's. The other approach, Schramm-Loewner evolutions (SLEs), is a recently introduced set of mathematical methods to study random curves or interfaces occurring in the continuum limit of the models. The first and second included articles argue on basis of statistical mechanics what would be a plausible relation between SLEs and conformal field theory. The first article studies multiple SLEs, several random curves simultaneously in a domain. The proposed definition is compatible with a natural commutation requirement suggested by Dubédat. The curves of multiple SLE may form different topological configurations, ``pure geometries''. We conjecture a relation between the topological configurations and CFT concepts of conformal blocks and operator product expansions. Example applications of multiple SLEs include crossing probabilities for percolation and Ising model. The second article studies SLE variants that represent models with boundary conditions implemented by primary fields. The most well known of these, SLE(kappa, rho), is shown to be simple in terms of the Coulomb gas formalism of CFT. In the third article the space of local martingales for variants of SLE is shown to carry a representation of Virasoro algebra. Finding this structure is guided by the relation of SLEs and CFTs in general, but the result is established in a straightforward fashion. This article, too, emphasizes multiple SLEs and proposes a possible way of treating pure geometries in terms of Coulomb gas. The fourth article states results of applications of the Virasoro structure to the open questions of SLE reversibility and duality. Proofs of the stated results are provided in the appendix. The objective is an indirect computation of certain polynomial expected values. Provided that these expected values exist, in generic cases they are shown to possess the desired properties, thus giving support for both reversibility and duality.

The Art of Adaptation : A study on the Europeanization of Finland's foreign and security policy

This study examines how Finnish foreign and security policy has been influenced by the European Union and its Common Foreign and Security Policy. It points to a growing interplay and misfit between the external expectations originating from the European level and the domestic expectations and traditional ways-of-doing-things. It is concluded that the deepening European integration in the sphere of foreign, security and defence policy has played a significant role in a number of transformations in the Finnish policies since 1995. New, more European, meanings have been attached to the key concepts of Finnish foreign and security policy. Neutrality and traditional peacekeeping have been replaced by a minimalist reading of military non-alignment and participation in crisis management operations and EU battle groups. Traditional small state identity has been recast more and more as small member stateness . At the same time Finland has entered an era of post-consensus in national foreign and security policy. A key theoretical argument in the background of the study is that collective understandings attached to European policies, when not resonating well with domestic understandings, cause adaptation pressures on domestic-level processes and may lead to changes in the way interests and identities are constructed. This means that Europeanization is principally seen as identity reconstruction. Consequently, the theoretical framework of the study builds on the Europeanization research literature and constructivist IR theory on state identity. Foreign and security policy is defined as the practice in which state identity is reproduced, and the key foreign and security policy concepts are seen as the vehicles of identity production. It is concluded that for Finland, participation in the EU s foreign, security and defence policies represents not only a tool for responding to the changes in the international security environment but also a new means of self-identification. Concerning the Finnish attempts of projecting national interests on the European security policy agenda, it is concluded that they mainly relate to the compatibility of the potential development of EU s defence dimension with the Finnish military non-alignment. Although neutrality was cast aside in the official security policy when Finland joined the EU, the analysis shows that its impact has continued in the domestic political debate and in the mind-set of the decision-makers. The primary research material includes official Finnish foreign and security policy documentation and the related parliamentary debates from 1994 to 2007. This study serves also as a comprehensive empirical overview on Finland s reactions and contributions to the EU Common Foreign and Security Policy.

From One Segment to a Segment of One - The Evolution of Market Segmentation Theory

The purpose of this study was to deepen the understanding of market segmentation theory by studying the evolution of the concept and by identifying the antecedents and consequences of the theory. The research method was influenced by content analysis and meta-analysis. The evolution of market segmentation theory was studied as a reflection of evolution of marketing theory. According to this study, the theory of market segmentation has its roots in microeconomics and it has been influenced by different disciplines, such as motivation research and buyer behaviour theory. Furthermore, this study suggests that the evolution of market segmentation theory can be divided into four major eras: the era of foundations, development and blossoming, stillness and stagnation, and the era of re-emergence. Market segmentation theory emerged in the mid-1950’s and flourished during the period between mid-1950’s and the late 1970’s. During the 1980’s the theory lost its interest in the scientific community and no significant contributions were made. Now, towards the dawn of the new millennium, new approaches have emerged and market segmentation has gained new attention.

Phase space methods and the Hamilton-Jacobi form of dynamics

A general analysis of the Hamilton-Jacobi form of dynamics motivated by phase space methods and classical transformation theory is presented. The connection between constants of motion, symmetries, and the Hamilton-Jacobi equation is described.

Microfoundations of HRM effects: Individual and Collective Attitudes and Performance

Previous research on Human Resource Management (HRM) has focused extensively on the potential relationships between the use of HRM practices and organizational performance. Extant research in HRM has been based on the underlying assumption that HRM practices can enhance organizational performance through their impact on positive employee attitudes and performance, that is, employee reactions to HRM. At the current state of research however, it remains unclear how employees come to perceive and react to HRM practices and to what extent employees in organizations, units and teams react to such practices in similar or widely different ways. In fact, recent HRM studies indicate that employee reactions to HRM may be far less homogeneous than assumed. This raises the question of whether or not the linkage between HRM and organizational outcomes can be explained by employee reactions in terms of attitudes and performance, if these reactions are largely idiosyncratic. Accordingly, this thesis aims to shed light on the processes that shape individuals’ reactions to HRM practices and how these processes may influence the variance or sharedness in such reactions among employees in organizations, units and teams. By theoretically developing and empirically examining the effects of employee perceptions of HRM practices from the perspective of ‘HRM as signaling’ and psychological contract theory, the main contributions of this thesis focus on the following research questions: i) How employee perceptions of the HRM practices relate to individual and collective employee attitudes and performance. ii) How employee perceptions of HRM practices relates to variance in employee attitudes and performance. iii) How collective employee performance mediates the relationship between employee perceptions of HRM practices and organizational performance. Regarding the first research questions the findings indicate that individuals do respond positively to HRM practices by adjusting their felt obligations towards the employer. This finding is in line with the idea of HRM as a signaling device where each HRM practice, implicitly or explicitly, sends signals to employees about promised rewards (inducements) and behaviors (obligations) expected in return. The relationship was also confirmed at the group level of analysis. What is more, variance was found to play an important role in that employee groups with more similar perceptions about the HRM system displayed a stronger relationship between HRM and employee obligations. Concerning the second question the findings were somewhat contradictory in that a strong HRM system was found negatively related to variance in employee performance but not employee obligations. Regarding the third question, the findings confirmed linkages between the HRM system and organizational performance at the group level and the HRM system and employee performance at the individual level. Also, the entire chain of links from the HRM system through variance in employee performance, and further through the level of employee performance to organizational performance was significant.

From ‘Afflicted’ to Activists: Structural Violence and Climate Change Discourse in the States of Pernambuco and Paraíba in Northeast Brazil

This study approaches the problem of poverty in the hinterlands of Northeast Brazil through the concept of structural violence, linking the environmental threats posed by climate change, especially those related to droughts, to the broader social struggles in the region. When discussions about potentials and rights are incorporated into the problematic of poverty, a deeper insight is obtained regarding the various factors behind the phenomenon. It is generally believed that climate change is affecting the already marginalized and poor more than those of higher social standing, and will increasingly do so in the future. The data for this study was collected during a three month field work in the states of Pernambuco and Paraíba in Northeast Brazil. The main methods used were semi-structured interviews and participant observation, including attending seminars concerning climate change on the field. The focus of the work is to compare both layman and expert perceptions on what climate change is about, and question the assumptions about its effects in the future, mainly that of increased numbers of ‘climate refugees’ or people forced to migrate due to changes in climate. The focus on droughts, as opposed to other manifestations of climate change, arises from the fact that droughts are not only phenomena that develop over a longer time span than floods or hurricanes, but is also due to the historical persistence of droughts in the region, and both the institutional and cultural linkages that have evolved around it. The instances of structural violence that are highlighted in this study; the drought industry, land use, and the social and power relations present in the region, including those between the civil society, the state and the private agribusiness sector, all work against a backdrop of symbolic and moral realms of value production, where relations between the different actors are being negotiated anew with the rise of the climate change discourse. The main theoretical framework of the study consists of Johan Galtung’s and Paul Farmer’s theory of structural violence, Ulrich Beck’s theory of the risk society, and James Scott’s theory of everyday peasant resistance.

Paradox between democracy and security- case study on Pakistan

Pro gradu-tutkielma tutkii demokratian ja turvallisuuden paradoksia Pakistanissa esitellen kuusi tekijää, jotka vaikuttavat kyseiseen paradoksiin. Näitä tekijöitä ovat historiallinen kehitys; eliittihallinto; taloudellinen kehitys; Pakistanin poliittisten tekijöiden demokratian eri määritelmät; opetuksen puuttuminen; ja valtataistelu hallituksen, armeijan, tiedustelupalvelun, oikeusjärjestelmän, poliittisten puolueiden sekä eri heimojen, uskonnollisten ja etnisten ryhmien välillä. Tutkimus tarkastelee myös sitä miten nämä tekijät vaikuttavat demokratian kehitykseen Pakistanissa. Keskeinen argumentti on, että länsimainen demokratia ei esiinny eikä toimi Pakistanissa vallitsevissa oloissa, etenkin historiallisen kehityksen ja ulkoisen turvallisuuden takia. Pro gradu-tutkielma käyttää sekundäärisiä lähteitä, kuten kirjoja, artikkeleita, maaraportteja, kommentaareja sekä omiin kokemuksiin perustuvia havaintoja Pakistanin matkalta 2010-2011. Keskeiset teoriat gradussa ovat Guillermo O’ Donnelin delegaattidemokratia sekä Duncan McCargon eliittihallintoteoria, jotka yhdessä selittävät historiallista kehitystä ja eliittihallinnon dynamiikkaa, mitkä johtavat paradoksiin. Kautta historian armeija on hallinnut Pakistania, ja siviilihallinto on ainoastaan neljä kertaa onnistunut olemaan vallassa, mutta silloinkin siviilihallinto päättyi korruptioväitteisiin tai armeijan vallankaappaukseen. Armeijahallinnoille on luonteenomaista hyvät suhteet USA:n, positiivinen taloudellinen kehitys ja vakaus, kun taas siviilihallinnot ovat epävakaita ja korruptoituneita. Tämä kehitys on paradoksin tausta, joka rakentuu turvallisuuspoliittisen tilanteen pohjalle eli hallitusten ja muiden tekijöiden yritykseen löytää vastapaino Intian uhalle. Tämä on ollut keskeinen huoli kelle tahansa poliittiselle päättäjälle itsenäisyydestä lähtien. Loputon valtataistelu eri poliittisten tekijöiden kesken sekä eliittihallinto pitävät yllä paradoksia, koska eliitit ovat kiinnostuneempia oman valtansa säilyttämisestä kuin kansan tahdon huomioonottamisesta. Koska valtaosa ihmisistä ei ole koulutettuja, he ovat paljolti kiinnostuneita omasta selviytymisestään, ja tämän takia sekä kansa että eliitit suosivat armeijahallintoa, koska se tuo vakautta ja taloudellista kehitystä. Sen vuoksi vallitsevissa oloissa demokratian tulevaisuus Pakistanissa näyttää huonolta, koska liberaalidemokratian vaatimukset eivät täyty puoliksi vapaan oikeussysteemin, puoliksi vapaan lehdistön, valtavan korruption ja monien ihmisoikeusloukkauksien takia unohtamatta armeijan ja tiedustelupalvelun sekaantumista siviilihallintoon.

Network approach for capturing ligand-induced subtle global changes in protein structures

Ligand-induced conformational changes in proteins are of immense functional relevance. It is a major challenge to elucidate the network of amino acids that are responsible for the percolation of ligand-induced conformational changes to distal regions in the protein from a global perspective. Functionally important subtle conformational changes (at the level of side-chain noncovalent interactions) upon ligand binding or as a result of environmental variations are also elusive in conventional studies such as those using root-mean-square deviations (r.m.s.d.s). In this article, the network representation of protein structures and their analyses provides an efficient tool to capture these variations (both drastic and subtle) in atomistic detail in a global milieu. A generalized graph theoretical metric, using network parameters such as cliques and/or communities, is used to determine similarities or differences between structures in a rigorous manner. The ligand-induced global rewiring in the protein structures is also quantified in terms of network parameters. Thus, a judicious use of graph theory in the context of protein structures can provide meaningful insights into global structural reorganizations upon perturbation and can also be helpful for rigorous structural comparison. Data sets for the present study include high-resolution crystal structures of serine proteases from the S1A family and are probed to quantify the ligand-induced subtle structural variations.

Modified Kirchhoffs theory of plates including transverse shear deformations

A primary flexure problem defined by Kirchhoff theory of plates in bending is considered. Significance of auxiliary function introduced earlier in the in-plane displacements in resolving Poisson-Kirchhoffs boundary conditions paradox is reexamined with reference to reported sixth order shear deformation theories, in particular, Reissner's theory and Hencky's theory. Sixth order modified Kirchhoff's theory is extended here to include shear deformations in the analysis. (C) 2011 Elsevier Ltd. All rights reserved.

Impact of Energy Expenditure Rate Constraints on the performance of Multihop Wireless Mesh Networks

In this article we study the problem of joint congestion control, routing and MAC layer scheduling in multi-hop wireless mesh network, where the nodes in the network are subjected to maximum energy expenditure rates. We model link contention in the wireless network using the contention graph and we model energy expenditure rate constraint of nodes using the energy expenditure rate matrix. We formulate the problem as an aggregate utility maximization problem and apply duality theory in order to decompose the problem into two sub-problems namely, network layer routing and congestion control problem and MAC layer scheduling problem. The source adjusts its rate based on the cost of the least cost path to the destination where the cost of the path includes not only the prices of the links in it but also the prices associated with the nodes on the path. The MAC layer scheduling of the links is carried out based on the prices of the links. We study the e�ects of energy expenditure rate constraints of the nodes on the optimal throughput of the network.

Combinatorial Representations of Block Codes

We look at graphical descriptions of block codes known as trellises, which illustrate connections between algebra and graph theory, and can be used to develop powerful decoding algorithms. Trellis sizes for linear block codes are known to grow exponentially with the code parameters. Of considerable interest to coding theorists therefore, are more compact descriptions called tail-biting trellises which in some cases can be much smaller than any conventional trellis for the same code . We derive some interesting properties of tail-biting trellises and present a new decoding algorithm.