Showing papers by "University of Trento published in 2004"

Classification of hyperspectral remote sensing images with support vector machines

Abstract: This paper addresses the problem of the classification of hyperspectral remote sensing images by support vector machines (SVMs) First, we propose a theoretical discussion and experimental analysis aimed at understanding and assessing the potentialities of SVM classifiers in hyperdimensional feature spaces Then, we assess the effectiveness of SVMs with respect to conventional feature-reduction-based approaches and their performances in hypersubspaces of various dimensionalities To sustain such an analysis, the performances of SVMs are compared with those of two other nonparametric classifiers (ie, radial basis function neural networks and the K-nearest neighbor classifier) Finally, we study the potentially critical issue of applying binary SVMs to multiclass problems in hyperspectral data In particular, four different multiclass strategies are analyzed and compared: the one-against-all, the one-against-one, and two hierarchical tree-based strategies Different performance indicators have been used to support our experimental studies in a detailed and accurate way, ie, the classification accuracy, the computational time, the stability to parameter setting, and the complexity of the multiclass architecture The results obtained on a real Airborne Visible/Infrared Imaging Spectroradiometer hyperspectral dataset allow to conclude that, whatever the multiclass strategy adopted, SVMs are a valid and effective alternative to conventional pattern recognition approaches (feature-reduction procedures combined with a classification method) for the classification of hyperspectral remote sensing data

Tropos: An Agent-Oriented Software Development Methodology

Abstract: Our goal in this paper is to introduce and motivate a methodology, called Tropos,1 for building agent oriented software systems. Tropos is based on two key ideas. First, the notion of agent and all related mentalistic notions (for instance goals and plans) are used in all phases of software development, from early analysis down to the actual implementation. Second, Tropos covers also the very early phases of requirements analysis, thus allowing for a deeper understanding of the environment where the software must operate, and of the kind of interactions that should occur between software and human agents. The methodology is illustrated with the help of a case study. The Tropos language for conceptual modeling is formalized in a metamodel described with a set of UML class diagrams.

Doing Gender, Doing Entrepreneurship: An Ethnographic Account of Intertwined Practices

Abstract: Traditional literature and research on entrepreneurship relies on a model of economic rationality alleged to be universal and agendered. This article presents a description of the processes that position people as ‘men’ and ‘women’ within entrepreneurial practices and as ‘entrepreneurs’ within gender practices, relying on an ethnographic study carried out in small enterprises in Italy. Our analysis shows how gender and entrepreneurship are enacted as situated practices and how the codes of a gendered identity are kept, changed and transgressed by constantly sliding between different symbolic spaces. In particular we highlight five processes of the symbolic construction of gender and entrepreneurship: managing the dual presence, doing ceremonial and remedial work, boundary-keeping, footing and gender commodification. We then propose a final metaphor which conveys a summary image of these processes. In concluding, we link our analysis to the original purpose of our investigation, highlighting not only how entrepreneurship is equated with the masculine, but also how alternative and possible forms of entrepreneurship exist, in the same way as different forms of gender.

Entrepreneur‐mentality, gender and the study of women entrepreneurs

Abstract: Uses the neologism “entrepreneur mentality” – paying implicit homage to Foucault's govermentality – to highlight how an entrepreneurial discourse is mobilized as a system of thinking about women entrepreneurs which is able to make some form of that activity thinkable and practicable, namely: who can be an entrepreneur, what entrepreneurship is, what or who is managed by that form of governance of economic relations? Discourses on women entrepreneurs are linguistic practices that create truth effects. Argues that social studies of women entrepreneurs tend to reproduce an androcentric entrepreneur mentality that makes hegemonic masculinity invisible. They portray women's organizations as “the other”, and sustain social expectations of their difference, thereby implicitly reproducing male experience as a preferred normative value. Taking a deconstructive gaze on how an entrepreneur‐mentality discourse is gendered, reveals the gender sub‐text underpinning the practices of the scientific community that study women entrepreneurs and, in so doing, open a space to question them.

E-commerce and tourism

Abstract: Travel and tourism are illustrating how e-commerce can change the structure of an industry---and in the process create new business opportunities.

Principles of a brain-computer interface (BCI) based on real-time functional magnetic resonance imaging (fMRI)

Abstract: A brain-computer interface (BCI) based on functional magnetic resonance imaging (fMRI) records noninvasively activity of the entire brain with a high spatial resolution. We present a fMRI-based BCI which performs data processing and feedback of the hemodynamic brain activity within 1.3 s. Using this technique, differential feedback and self-regulation is feasible as exemplified by the supplementary motor area (SMA) and parahippocampal place area (PPA). Technical and experimental aspects are discussed with respect to neurofeedback. The methodology now allows for studying behavioral effects and strategies of local self-regulation in healthy and diseased subjects.

S-Match: An algorithm and an implementation of semantic matching

Abstract: We think of Match as an operator which takes two graph-like structures (e.g., conceptual hierarchies or ontologies) and produces a mapping between those nodes of the two graphs that correspond semantically to each other. Semantic matching is a novel approach where semantic correspondences are discovered by computing, and returning as a result, the semantic information implicitly or explicitly codified in the labels of nodes and arcs. In this paper we present an algorithm implementing semantic matching, and we discuss its implementation within the S-Match system. We also test S-Match against three state of the art matching systems. The results, though preliminary, look promising, in particular for what concerns precision and recall.

Equation of State of a Fermi Gas in the BEC-BCS Crossover: A Quantum Monte Carlo Study

Abstract: We calculate the equation of state of a two-component Fermi gas with attractive short-range interspecies interactions using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value $a$ of the $s$-wave scattering length of the two-body potential. For $ag0$ and $a$ smaller than the inverse Fermi wave vector our results show a molecular regime with repulsive interactions well described by the dimer-dimer scattering length ${a}_{m}=0.6a$. The pair correlation functions of parallel and opposite spins are also discussed as a function of the interaction strength.

Automated composition of semantic web services into executable processes

Abstract: Different planning techniques have been applied to the problem of automated composition of web services. However, in realistic cases, this planning problem is far from trivial: the planner needs to deal with the nondeterministic behavior of web services, the partial observability of their internal status, and with complex goals expressing temporal conditions and preference requirements. We propose a planning technique for the automated composition of web services described in OWLS process models, which can deal effectively with nondeterminism, partial observability, and complex goals. The technique allows for the synthesis of plans that encode compositions of web services with the usual programming constructs, like conditionals and iterations. The generated plans can thus be translated into executable processes, e.g., BPEL4WS programs. We implement our solution in a planner and do some preliminary experimental evaluations that show the potentialities of our approach, and the gain in performance of automating the composition at the semantic level w.r.t. the automated composition at the level of executable processes.

Line broadening analysis using integral breadth methods: a critical review

Abstract: Integral breadth methods for line profile analysis are reviewed, including modifications of the Williamson–Hall method recently proposed for the specific case of dislocation strain broadening. Two cases of study, supported by the results of a TEM investigation, are considered in detail: nanocrystalline ceria crystallized from amorphous precursors and highly deformed nickel powder produced by extensive ball milling. A further application concerns a series of Fe–Mo powder specimens that were ball milled for increasing time. Traditional and modified Williamson–Hall methods confirm their merits for a rapid overview of the line broadening effects and possible understanding of the main causes. However, quantitative results are generally not reliable. Limits in the applicability of integral breadth methods and reliability of the results are discussed in detail.

Using Trust in Recommender Systems: An Experimental Analysis

Abstract: Recommender systems (RS) have been used for suggesting items (movies, books, songs, etc.) that users might like. RSs compute a user similarity between users and use it as a weight for the users’ ratings. However they have many weaknesses, such as sparseness, cold start and vulnerability to attacks. We assert that these weaknesses can be alleviated using a Trust-aware system that takes into account the “web of trust” provided by every user.

Expert and public perception of risk from biotechnology.

Abstract: Risk perceptions of a series of biotechnology applications were examined in a public (nonexpert) sample and an expert sample. Compared with the experts, the public perceived all biotechnology applications as more risky. Both groups perceived food-related applications to be riskier than medical applications. Compared with the public, experts perceived both food and medical applications as less harmful and more useful. Experts also judged the risks posed from medical biotechnology applications as more familiar and acknowledged by people and science. Lay estimates of the risk of food applications were predicted by potential harm, potential benefits, science knowledge, and familiarity; experts' estimates were predicted only by harm and benefits. Lay estimates of the risk of medical applications were predicted by potential harm; experts' estimates were predicted by potential benefits, number and type of people exposed, and science knowledge. We discuss the implications of the results for risk communication about and management of different types of biotechnologies.

Brain activity underlying emotional valence and arousal: A response-related fMRI study

Abstract: Emotional behavior is organized along two psychophysiologic dimensions: (1) valence, varying from negative to positive, and (2) arousal, varying from low to high. Behavioral responses along these dimensions are assumed to be mediated by different brain circuits. We recorded startle reflex modulation and skin conductance responses in healthy volunteers during functional magnetic resonance imaging (fMRI) while they viewed a set of emotional pictures and took verbal ratings of the emotional valence and arousal of each picture after scanning. Response-related multiple correlation analysis revealed differential brain activity in five brain regions. Startle reflex changes, associated with the valence of a stimulus, correlated with activity in the amygdala, while verbal reports of negative emotional valence varied with insular activity. Peripheral physiologic and verbal responses along the arousal dimension varied with thalamic and frontomedial activity. Peripheral physiologic responses along both dimensions correlated with activity in somatosensory association areas in the anterior parietal cortex. In the valence dimension, activity in the left anterior parietal cortex was associated with highly correlating peripheral physiologic and verbal responses, suggesting that verbal reports of emotional valence might depend partly on brain circuits representing peripheral physiologic changes. Our data provide direct evidence for a functional segregation of brain structures underlying peripheral physiologic responses and verbal ratings along the emotional dimensions of valence and arousal.

Dimensions of "uniquely" and "non-uniquely" human emotions.

Abstract: Emotion scientists often distinguish those emotions that are encountered universally, even among animals ("primary emotions"), from those experienced by human beings ("secondary emotions"). No attempt, however, has ever been made to capture the lay conception about this distinction and to find the criteria on which the distinction is based. The first study presented in this paper was conducted in three countries involving four languages, so as to allow for cross-cultural comparisons. Results showed a remarkable convergence. People from all samples not only differentiated between "uniquely human" and "non-uniquely human" emotions on a continuum, but they did so on the same basis as the one used by emotion scientists to distinguish between "primary" and "secondary" emotions. Study 2 focused on the implicit use of such a distinction. When confronted with a human (animal) context, participants reacted faster to secondary (vs primary) emotions. The implications of the human uniqueness of some emotions within the social and interpersonal contexts are discussed.

Self-regulation of local brain activity using real-time functional magnetic resonance imaging (fMRI).

Abstract: Functional magnetic resonance imaging (fMRI) measures the blood oxygen level-dependent (BOLD) signal related to neuronal activity. So far, this technique has been limited by time-consuming data analysis impeding on-line analysis. In particular, no brain-computer interface (BCI) was available which provided on-line feedback to learn physiological self-regulation of the BOLD signal. Recently, studies have shown that fMRI feedback is feasible and facilitates voluntary control of brain activity. Here we review these studies to make the fMRI feedback methodology accessible to a broader scientific community such as researchers concerned with functional brain imaging and the neurobiology of learning. Methodological and conceptual limitations were substantially reduced by artefact control, sensitivity improvements, real-time algorithms, and adapted experimental designs. Physiological self-regulation of the local BOLD response is a new paradigm for cognitive neuroscience to study brain plasticity and the functional relevance of regulated brain areas by modification of behaviour. Voluntary control of abnormal activity in circumscribed brain areas may even be applied as psychophysiological treatment.

Market research for requirements analysis using linguistic tools

Abstract: Numerous studies in recent months have proposed the use of linguistic instruments to support requirements analysis. There are two main reasons for this: (i) the progress made in natural language processing and (ii) the need to provide the developers of software systems with support in the early phases of requirements definition and conceptual modelling. This paper presents the results of an online market research intended (a) to assess the economic advantages of developing a CASE (computer-aided software engineering) tool that integrates linguistic analysis techniques for documents written in natural language, and (b) to verify the existence of the potential demand for such a tool. The research included a study of the language – ranging from completely natural to highly restricted – used in documents available for requirements analysis, an important factor given that on a technological level there is a trade-off between the language used and the performance of the linguistic instruments. To determine the potential demand for such tool, some of the survey questions dealt with the adoption of development methodologies and consequently with models and support tools; other questions referred to activities deemed critical by the companies involved. Through statistical correspondence analysis of the responses, we were able to outline two “profiles” of companies that correspond to two potential market niches, which are characterised by their very different approach to software development.

Specifying and analyzing early requirements in Tropos

Abstract: We present a framework that supports the formal verification of early requirements specifications. The framework is based on Formal Tropos, a specification language that adopts primitive concepts for modeling early requirements (such as actor, goal, and strategic dependency), along with a rich temporal specification language. We show how existing formal analysis techniques, and in particular model checking, can be adapted for the automatic verification of Formal Tropos specifications. These techniques have been implemented in a tool, called the T-Tool, that maps Formal Tropos specifications into a language that can be handled by the NuSMV model checker. Finally, we evaluate our methodology on a course-exam management case study. Our experiments show that formal analysis reveals gaps and inconsistencies in early requirements specifications that are by no means trivial to discover without the help of formal analysis tools.

Beta binders for biological interactions

Abstract: This paper presents binders and operators, in the process calculi tradition, to reason about biological interactions. Special binders are added to wrap a process just as membranes enclose some living matter and hence to mimick biological interfaces. A few operators are then added to the pi-calculus kernel to describe the dynamics of those interfaces.

Spatial constraints on visual-tactile cross-modal distractor congruency effects.

Abstract: Across three experiments, participants made speeded elevation discrimination responses to vibrotactile targets presented to the thumb (held in a lower position) or the index finger (upper position) of either hand, while simultaneously trying to ignore visual distractors presented independently from either the same or a different elevation. Performance on the vibrotactile elevation discrimination task was slower and less accurate when the visual distractor was incongruent with the elevation of the vibrotactile target (e.g., a lower light during the presentation of an upper vibrotactile target to the index finger) than when they were congruent, showing that people cannot completely ignore vision when selectively attending to vibrotactile information. We investigated the attentional, temporal, and spatial modulation of these cross-modal congruency effects by manipulating the direction of endogenous tactile spatial attention, the stimulus onset asynchrony between target and distractor, and the spatial separation between the vibrotactile target, any visual distractors, and the participant’s two hands within and across hemifields. Our results provide new insights into the spatiotemporal modulation of crossmodal congruency effects and highlight the utility of this paradigm for investigating the contributions of visual, tactile, and proprioceptive inputs to the multisensory representation of peripersonal space.

Planning and Monitoring Web Service Composition

Abstract: The ability to automatically compose web services, and to monitor their execution, is an essential step to substantially decrease time and costs in the development, integration, and maintenance of complex services. In this paper, we exploit techniques based on the “Planning as Model Checking” approach to automatically compose web services and synthesize monitoring components. By relying on such a flexible technology, we are able to deal with the difficulties stemming from the unpredictability of external partner services, the opaqueness of their internal status, and the presence of complex behavioral requirements. We test our approach on a simple, yet realistic example; the results provide a witness to the potentiality of this approach.

Probing microcavity polariton superfluidity through resonant Rayleigh scattering

Abstract: We study the motion of a polariton fluid injected into a planar microcavity by a continuous wave laser. In the presence of static defects, the spectrum of the Bogoliubov-like excitations reflects onto the shape and intensity of the resonant Rayleigh scattering emission pattern in both momentum and real space. We find a superfluid regime in which the Rayleigh scattering ring in momentum space collapses as well as its normalized intensity. We show how collective excitation spectra having no analog in equilibrium systems can be observed by tuning the excitation angle and frequency.

Entropy and universality of Cardy-Verlinde formula in dark energy universe

Abstract: We study the entropy of a FRW universe filled with dark energy (cosmological constant, quintessence, or phantom). For the general or time-dependent equation of state $p=w\ensuremath{\rho}$ the entropy is expressed in terms of energy, Casimir energy, and w. The corresponding expression is reminiscent of the 2D conformal field theory (CFT) entropy only for conformal matter. At the same time, the cosmological Cardy-Verlinde formula relating three typical FRW universe entropies remains universal for any type of matter. The same conclusions hold in modified gravity, which represents the gravitational alternative for dark energy and which contains terms that increase at low curvature. It is interesting that black holes in modified gravity are more entropic than those in Einstein gravity. Finally, some hydrodynamical examples testing the new shear viscosity bound, which is expected to be the consequence of the holographic entropy bound, are presented for the early Universe in the plasma era and for the Kasner metric. It seems that the Kasner metric provides a counterexample to the new shear viscosity bound.

Observation of dynamical instability for a Bose-Einstein condensate in a moving 1D optical lattice.

Abstract: We have experimentally studied the unstable dynamics of a harmonically trapped Bose-Einstein condensate loaded into a 1D moving optical lattice. The lifetime of the condensate in such a potential exhibits a dramatic dependence on the quasimomentum state. This is unambiguously attributed to the onset of dynamical instability, after a comparison with the predictions of the Gross-Pitaevskii theory. Deeply in the unstable region we observe the rapid appearance of complex structures in the atomic density profile, as a consequence of the condensate phase uniformity breakdown.

Organizations, coalitions, and movements

Abstract: This article uses empirical evidence on networks of voluntary organizations mobilizing on ethnic minority, environmental, and social exclusion issues in two British cities, to differentiate between social movement processes and other, cognate collective action dynamics. Social movement processes are identified as the building and reproducing of dense informal networks between a multiplicity of actors, sharing a collective identity, and engaged in social and/or political conflict. They are contrasted to coalitional processes, where alliances to achieve specific goals are not backed by significant identity links, and organizational processes, where collective action takes place mostly in reference to specific organizations rather than broader, looser networks.

Motion of a heavy impurity through a Bose-Einstein condensate

Abstract: We study the motion of a pointlike impurity in a Bose-Einstein condensate at $T=0$. By solving the Gross-Pitaevskii (GP) equation in a perturbative manner we calculate the induced mass of the impurity and the drag force on the impurity in three-, two-, and one-dimensional (1D) cases. The relationship between the induced mass and the normal mass of fluid is found, and coincides with the result of the Bogoliubov theory. The drag force appears for the supersonic motion of the impurity. In 1D the drag force is investigated also on the basis of the exact Lieb-Liniger theory, using the dynamic form factor, which has been evaluated by the Haldane method of the calculation of correlation functions. In this theory the force appears for an arbitrarily small velocity of the impurity. The possibility of measuring the form factor in existing experiments is noted.

The solid surface free energy calculation. I. In defense of the multicomponent approach.

Abstract: The acid-base approach to the calculation of solid surface free energy and liquid-liquid interfacial tensions is a practical example of application of correlation analysis, and thus it is an approximate approach. In these limits, and provided that wide and well-obtained sets of contact angles or interfacial tension data are used for their computation, surface tension components can be considered as material properties. Although their numerical value depends on the characteristics of the chosen reference material, their chemical meaning is independent on the selected scale. Contact angles contain accessible information about intermolecular forces; using surface tension component (STC) acid-base theory, one can extract this information only making very careful use of the mathematical apparatus of correlation analysis. The specific mathematical methods used to obtain these results are illustrated by using as an example a base of data obtained by the supporters of the equation-of-state theory (EQS). The achievements are appreciably good and the agreement between STC and EQS is discussed.