Evaluating tag-based information access in image collections

The availability of social tags has greatly enhanced access to information. Tag clouds have emerged as a new "social" way to find and visualize information, providing both one-click access to information and a snapshot of the "aboutness" of a tagged collection. A range of research projects explored and compared different tag artifacts for information access ranging from regular tag clouds to tag hierarchies. At the same time, there is a lack of user studies that compare the effectiveness of different types of tag-based browsing interfaces from the users point of view. This paper contributes to the research on tag-based information access by presenting a controlled user study that compared three types of tag-based interfaces on two recognized types of search tasks - lookup and exploratory search. Our results demonstrate that tag-based browsing interfaces significantly outperform traditional search interfaces in both performance and user satisfaction. At the same time, the differences between the two types of tag-based browsing interfaces explored in our study are not as clear. Copyright 2012 ACM

Genealogy of behaviourist peace research

This paper presents the behaviourist “non-normative” Peace Research (PR) tradition with two objectives. One objective is to locate this field in relation to closely related fields of research. PR specificity is: the dependent variable of peace and conflict when compared with Political Science and International Relations; the normative concern with the causes of war when compared with Strategic Studies; and the rejection of the “practicality” of research and a restraint on normativity when compared with Peace Studies (defined as peace research, peace teaching and peace action) and Conflict Resolution. Also, PR is considered here as one of the sub-fields of International Security Studies. The second objective of the paper is to present the history of PR. Since its creation in the 1950s, with a focus on inter-state conflict as an alternative to Strategic Studies, PR had two defining periods: one in the late 1960s labelled as the “socialist revolution”, with the conceptualisation of peace as more than the absence of war (positive peace) and a challenge for normativity in research; and a second period in the 1980s that brought the broadening of the referent object to intra-state conflict and liberal peace, and the emergence of other social sciences dedicated to the study of issues in, or close to, PR, broadly defined as security with some of them adopting a normative stance in research. The epistemological community of PR kept its behaviourist approach in spite of these two normative challenges, and its distinctiveness and unity is much due to its method

The context of conflict resolution : international relations and the study of peace and conflict

This paper provides a brief review of almost one century of academic research within the discipline of International Relations with a focus on the thinking about Peace and Conflict and its links to approaches in Conflict Resolution. The framework of analysis is based on the definition of science, what is studied and how it is studied, which delimits the analysis into the four debates in IR: between 1919 and the 1940s, the idealist versus realist debate; in the 1950s and 1960s, the traditionalist versus behaviourist debate; in the 1970s and 1980s, the inter-paradigm debate, and, since the 1990s, the rationalist versus reflectivist debate. This paper identifies how the classical conception of security centred on the state, the military and external threats was broadened by different approaches to include other actors (individuals, groups, societies, civilizations), other sectors (economic, political, social, environmental) and internal threats. In tandem, it maps the epistemological and sometimes ontological challenges to positivism and rationalism found in (Neo) Realism, (Neo) Liberalism and Marxism, by a set of post-positivist and reflective theories or approaches, such as the cases of Human Security, Feminism, Post-structuralism, Constructivism, Post-Colonialism, Critical Studies, and the Copenhagen School. The emergence and development of all these theories and approaches are historically contextualized alongside developments of Conflict Resolution approaches.info:eu-repo/semantics/publishedVersio

Magnetization pinning in modulated nanowires: from topological protection to the "corkscrew" mechanism

Diameter-modulated nanowires offer an important paradigm to design the magnetization response of 3D magnetic nanostructures by engineering the domain wall pinning. With the aim to understand its nature and to control the process, we analyze the magnetization response in FeCo modulated polycrystalline two-segment nanowires varying the minor diameter. Our modelling indicates a very complex behavior with a strong dependence on the disorder distribution and an important role of topologically non-trivial magnetization structures. We demonstrate that modulated nanowires with a small diameter difference are characterized by an increased coercive field in comparison to the straight ones which is explained by a formation of topologically protected walls formed by two 3D skyrmions with opposite chiralities. For a large diameter difference we report the occurrence of a novel pinning type called here the "corkscrew": the magnetization of the large diameter segment forms a skyrmion tube with a core position in a helical modulation along the nanowire. This structure is pinned at the constriction and in order to penetrate the narrow segments the vortex/skyrmion core size should be reduced

African Peace and Security Architecture (APSA) subsidiarity and the Horn of Africa: the Intergovernmental Authority on Development (IGAD)

The new African Peace and Security Architecture is based on the principle of subsidiarity governing the relationship between the United Nations, African Union and regional mechanisms. Nevertheless it is still unclear how subsidiarity will be implemented in the decision-making mechanism, division of labour and burden sharing. This paper analyses the challenges of subsidiarity in two IGAD processes: the renewal of the security mandate started at IGAD in 2005 and Ethiopian intervention in Somalia in 2006. It finds that regional rivalries and historical legacies prevent the development of IGAD’s security mandate and an intervention policy while international interests determine the projection of the Somalia case. It concludes that sub-regional inter-state institutional coordination and capacity-building are essential requirements for the implementation of subsidiarity.FCT - Fundação para a Ciência e a Tecnologi

Principais anomalias observadas em torres para radiocomunicações em Portugal

As torres são um dos principais suportes físicos para a instalação de equipamentos de rádio, utilizados para a emissão de ondas electromagnéticas que permitem serviços diver-sos, tais como rádio, televisão ou comunicações móveis. Em Portugal, na década de 90, houve uma enorme procura por este tipo de estruturas, sobretudo como resultado do enorme cresci-mento da cobertura para utilização em redes de comunicações móveis. Este trabalho pretende apresentar as principais anomalias observadas neste tipo de estruturas em Portugal

Acção do vento sobre torres: análises comparativas entre RSA e Eurocódigos

Neste trabalho indicam-se as principais diferenças que se podem observar ao nível da acção do vento, entre o Regulamento de Segurança e Acções (RSA) e Eurocódigos (EC), quando aplicáveis à análise e dimensionamento de torres. Para tal, procede-se à análise com-parativa de diversos parâmetros, colocando-se comentários gerais sobre cada um deles, para um melhor entendimento sobre a sua abordagem e filosofia. Finalmente, são apresentados, confrontados e discutidos os resultados obtidos de acordo com cada uma das normas mencio-nadas, tendo como base o caso de estudo de uma torre utilizada para radiocomunicações

Chain Homotopies for Object Topological Representations

This paper presents a set of tools to compute topological information of simplicial complexes, tools that are applicable to extract topological information from digital pictures. A simplicial complex is encoded in a (non-unique) algebraic-topological format called AM-model. An AM-model for a given object K is determined by a concrete chain homotopy and it provides, in particular, integer (co)homology generators of K and representative (co)cycles of these generators. An algorithm for computing an AM-model and the cohomological invariant HB1 (derived from the rank of the cohomology ring) with integer coefficients for a finite simplicial complex in any dimension is designed here. A concept of generators which are "nicely" representative cycles is also presented. Moreover, we extend the definition of AM-models to 3D binary digital images and we design algorithms to update the AM-model information after voxel set operations (union, intersection, difference and inverse)

The voter who wasn’t there : Referenda, representation and abstention

We analyze single binary-choice voting rules and identify the presence of the No-Show paradox in this simple setting, as a consequence of specific turnout or quorum conditions that are included in actual rules. Since these conditions are meant to ensure a representative outcome, we formalize this concern and reach our main result: no voting rule can ensure representation if abstention is possible, unless restrictive assumptions are made on the preference domain of abstainers. We then focus on the main referendum systems and show that appropriate restrictions do make them compatible with representation. The main purpose of our paper is, however, to provide a tool for referendum design: rather than imposing arbitrary restrictions on the preference domain of non-voters, we recommend instead that a conscious choice be made on how abstention is to be interpreted and that this choice be used to derive the corresponding referendum rule..info:eu-repo/semantics/publishedVersio