Dans ma thèse, j’étudie les représentations mentales et les processus cognitifs qui sous-tendent le calcul mental sur le marché. Cette thèse contribue à la recherche de prix psychologique en décrivant de nouveaux facteurs qui influencent les jugements de prix des consommateurs. En particulier, je découvre facteurs qui rendent les consommateurs plus ou moins susceptibles d’arrondir les prix vers le bas (Essai 1) et les facteurs qui déterminent leur tendance à se fixer sur les différences de pourcentage (Essai 3). En outre, cette recherche fournit de nouvelles perspectives à la littérature de budgétisation mentale en identifiant des stratégies de calcul mental qui conduisent à des estimations panier de prix plus précis (Essay 2). Dans l'ensemble, ma recherche va contribuer à notre compréhension des jugements de prix des consommateurs et proposer des contextes et des stratégies conduisant à des évaluations de prix plus précis. / In my dissertation I look at mental representations and cognitive processes that underlie mental arithmetic in the marketplace. This research contributes to behavioral pricing literature by outlining novel factors that influence consumers’ price difference judgments. Particularly, I uncover factors that make consumers more or less likely to fall prey to the left-digit anchoring bias (Essay 1) and factors that determine their tendency to rely on relative thinking in price difference evaluations (Essay 3). Further, this research provides new insights to the mental budgeting literature by identifying mental computation strategies that lead to more accurate basket price estimates (Essay 2). Overall, I expect my research to contribute to our understanding of consumers’ price judgments and suggest contexts and strategies leading to more accurate price evaluations.

Working memory training improves performance on trained and untrained working memory tasks, but there is little consistent evidence that these gains benefit everyday tasks that rely on working memory. Evidence has shown that transcranial electrical stimulation (tES) may be an effective tool for enhancing cognitive training and promoting transfer. In the first study, participants completed Cogmed working memory training with either active or sham transcranial random noise stimulation (tRNS). Training was associated with substantial gains on the training activities and on transfer measures of working memory with common processing and storage demands to the training tasks. tRNS did not enhance gains on trained or untrained activities. The second study systematically investigated the boundary conditions to training transfer by testing whether gains following backward digit recall (BDR) training transferred within- and across-paradigm to untrained backward recall and n-back tasks with varying degrees of overlap with the training activity. A further aim was to test whether transcranial direct current stimulation (tDCS) enhanced training and transfer. Participants were allocated to one of three conditions: (i) BDR training with active tDCS, (ii) BDR training with sham tDCS, or (iii) visual search control training with sham tDCS. The results indicated that training transfer is constrained by paradigm, but not by stimuli domain or stimuli materials. There was no evidence that tDCS enhanced performance on the training or transfer tasks. The results of Study 1 and Study 2 provide no evidence that tES enhances the benefits of working memory training. The absence of transfer between backward recall training and n-back in Study 2 suggested the tasks might tap into distinct aspects of working memory. Consequently, the final study used a latent variable approach to explore the degree of overlap between different forms of backward recall and n-back tasks containing digits, letters, or spatial locations as stimuli. The best-fitting factor model included two distinct but related (r = .68) constructs corresponding to backward recall and n-back. Both categories of task were linked to a separate fluid reasoning construct, providing evidence that both are valid measures of higher-order complex cognition. Overall, the experiments in this thesis suggest that working memory tasks tap into separate processes and that training may be targeting and improving these distinct processes, explaining the absence of cross-paradigm transfer.

Made available in DSpace on 2014-07-29T15:07:47Z (GMT). No. of bitstreams: 1 Dissertacao_Ingrid_Lima2.pdf: 1990693 bytes, checksum: 94c6742e78564bd3d1e8df861cc1c96c (MD5) Previous issue date: 2009-04-07 / Radiographic evaluation has been done lately as important diagnosis recourse for bovine locomotor injuries. However the scarcity of study in this area has made difficult the veterinary s performance. The aim of the study was to use radiographic exams to help in the characterization of the most important bone injuries that compromise bovine digit, metacarpophalangeal and metatarsophalangeal joint as well as relate radiographic findings to lameness sings and the presence of feet injuries. Participate in this study fifty male bovines (Zebu x European), confined, carrying locomotor alterations, with or without digital alteration, from the state of Goiás. All the animals were evaluated about the locomotion score the moment they arrived, and 112 days latter at the end of the confinement. After the slaughter, the four member distal extremities were collected (n=200) and evaluated about clinic and radiographic alterations. Claudication was found out in 86% of the animals. The locomotion scores were distributed as fallowing: 14% had score 1, 20% score 2, 52% score 3 and 14% score 4. The comparison between two moments, arrival and end of the confinement, demonstrated the aggravation of the locomotion score during the period the animals were confined. Only 29,5% from the extremities evaluated presented digital injuries. From these, 40,7% were classified as mixture, 32,2% septic pododermatitis, 11,9% interdigital dermatitis, 8,5% horn erosion and 68% as digital dermatitis. According to the radiographic evaluation 25,5% of the extremities presented some kind of digital alteration. The main injuries were distributed in joint degenerative disease (27,5%), osteitis (19,6%), periostitis (15,7%), septic arthritis in distal interphalangeal joint (11,8%), calcification off deep flexor tendon (7,8), calcification of the extensor tendon (5,9%), fracture in chip, ankylosis of joint and calcification of the proximal insertions of the cruciate ligaments (3,9% each one). The results showed relation between the presence of lameness and digital injuries with the radiographic alterations observed in the digits, however this relation was not found in the radiographic alterations of the fisis from metacarpophalangeal and metatarsophalangeal joints. We concluded that the locomotion score, associated to characterization of the podal injuries and the radiographic examination, helped in the diagnosis of lameness and that there is a relation among lameness, pedal injuries and radiographic alterations. It also showed that the confinement may be a determinating factor to the development of fiseal dysplasia in bovines, however, for better comprehension of the illness more radiographic studies that go along with the animal growth must be carried out / A avaliação radiográfica vem sendo aplicada, nos últimos anos, como importante meio de diagnóstico das desordens locomotoras de bovinos. Entretanto a escassez de estudos nessa área tem dificultado a atuação dos profissionais buiatras. Esse trabalho teve como objetivo utilizar o exame radiográfico para auxiliar a caracterização das principais lesões ósseas que comprometem os dígitos e as articulações metacarpo e metatarso-falangeana de bovinos, assim como relacionar os achados radiográficos aos sinais clínicos de claudicação e à presença de lesões podais. Foram utilizados 50 bovinos machos, cruzados manejados em sistema semi intensivo, portadores de alterações locomotoras, com ou sem lesões digitais, provenientes do Estado de Goiás. Todos os animais foram avaliados, quanto ao escore de locomoção no momento de chegada, e 112 dias depois no momento de saída do confinamento Após o abate foram colhidas as quatro extremidades distais (n=200), as mesmas foram avaliadas quanto a alterações clínicas e radiográficas. Quanto à avaliação de claudicação verificou-se que esteve presente em 86% dos animais, sendo os escores de locomoção assim distribuídos: 14% apresentavam escore 1, 20% escore 2, 52% escore 3 e 14% escore 4. A comparação entre o dois momentos, chegada e saída do confinamento, demonstrou que houve piora (p = 0,003) no escore de locomoção dos animais, durante o período em que permaneceram confinados. Em relação às 200 extremidades avaliadas apenas 29,5% apresentaram lesões digitais. Destas, 40,7%, foram classificadas como mistas, 32,2% pododermatite séptica, 11,9% dermatite interdigital, 8,5% erosão de talão e 6,8% classificadas como dermatite digital. Na avaliação radiográfica 25,5% das extremidades avaliadas apresentaram algum tipo de alteração nos dígitos. As principais lesões foram distribuídas entre doença degenerativa articular (27,5%), osteíte (19,6%), periostite (15,7%), artrite séptica da articulação interfalangeana distal (11,8%), calcificação do tendão flexor profundo (7,8%), calcificação do tendão extensor (5,9%), fratura em chip, artrite anquilosante e calcificação do ligamento cruzado proximal (3,9% cada uma). Os resultados demonstraram que houve relação entre a presença de claudicação e de lesões digitais com as alterações radiográficas observadas nos dígitos, entretanto essa mesma relação não esteve presente nas alterações radiográficas observadas nas fises das articulações metacarpo e metatarso-falangeanas. Conclui-se que o escore de locomoção, associado à caracterização das lesões podais e ao exame radiográfico auxiliou no diagnostico de claudicação e que existe relação entre, claudicação, lesões podais e alterações radiográficas e que o confinamento pode ser um fator determinante para o desenvolvimento das lesões de displasia fiseal em bovinos, entretanto para a melhor compreensão dessa enfermidade é necessário a realização de estudos radiográficos que acompanhem o animal durante seu crescimento

Today, it has become a natural part of life for many people to share personal information and turn to search engines and social media as they search and seek information on the internet. This study aims to investigate how individuals are affected by Big Data in their interactions with social media and to understand how individuals relate to personalization of Big Data, digital identity, agency and how they share their own personal data. This has been researched through a case study involving qualitative interviews and experiments. The result of the research shows that personalization of Big Data on social media has an impact on individuals in their ever yday lives. The research from this case study shows a certain negative attitude towards personalization on social media and that there is so me awareness of the companies agency on the internet, this does not affect individuals in taking any actions. This leads to the conclusion that personalization is to some extent a desired function. / Idag har det blivit en självklarhet för många att dela med sig av personlig information på internet och vända sig till sökmotorer och sociala medier när de letar och söker information. Studien syftar till att undersöka hur individer påverkas av Big Data i sin interaktion med sociala medier och att förstå hur individer förhåller sig till personalisering av Big data, digital identitet, aktörers makt och hur de tänker kring delning av personlig data. Detta studeras genom en fallstudie där kvalitativa intervjuer och experiment. Resultatet från studien visar att personalisering av Big Data på sociala medier påverkar individer och deras digitala användning i vardagen. Studien visar en viss negativ inställning till personalisering på sociala medier och på viss medvetenhet kring aktörernas makt på internet, detta påverkar inte individerna att göra aktiva handlingar. Detta leder till slutsatsen att personalisering av Big Data i viss mån är en accepterad funktion, även om det innebär en förlorad makt över sin digitala användning.

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There is a well-documented bidirectional relationship between pain and cognitive dysfunction, especially working memory. Despite this extensive body of research, the pain–working memory relationship is poorly understood. Pain catastrophizing – exaggerated negative cognitive and emotional responses towards pain – may contribute to working memory deficits by occupying finite, shared cognitive resources, but this has yet to be investigated. The present study sought to clarify the role of pain catastrophizing (assessed as both a trait-level disposition and state-level process) in working memory dysfunction. Healthy undergraduate participants were randomized to an ischemic pain or control task, during which they completed verbal and non-verbal working memory tests. They also completed measures of state- and trait-level pain catastrophizing. Mediation analyses indicated that state-level pain catastrophizing mediated the relationships of pain group to both verbal and non-verbal working memory, such that participants in the pain group (vs. the control group) catastrophized more about their pain, which then resulted in worse verbal and non-verbal working memory performance. In moderated mediation analyses, trait-level pain catastrophizing moderated this mediation effect for both verbal and non-verbal working memory. Those participants in the pain group who reported greater tendency to catastrophize about pain in general exhibited greater catastrophizing in-the-moment during the pain task, thereby leading to worse verbal and non-verbal working memory performance. These results provide evidence for pain catastrophizing as a putative mechanism and moderating factor of working memory dysfunction in pain. Future research should replicate these results in chronic pain samples, investigate other potential mechanisms (e.g., sleep), and develop interventions to ameliorate cognitive dysfunction by targeting pain catastrophizing.

Le thème de cette thèse est de comprendre la distribution des nombres premiers, qui est un sujet central de la théorie analytique des nombres. Plus précisément, nous allons prouver des théorèmes de type Bombieri-Vinogradov pour les nombres premiers avec un chiffre manquant dans leur développement b-adique pour un grand entier positif b. La preuve est basée sur la méthode du cercle, qui repose sur la structure de Fourier des entiers avec un chiffre manquant et les sommes exponentielles sur les nombres premiers dans les progressions arithmétiques. En combinant nos résultats avec le crible semi-linéaire, nous obtenons une borne supérieure et une borne inférieure avec le bon ordre de grandeur pour le nombre de nombres premiers de la forme p=1+m^2 + n^2 avec un chiffre manquant dans une grande base impaire b. / The theme of this thesis is to understand the distribution of prime numbers, which is a central topic in analytic number theory. More precisely, we prove Bombieri-Vinogradov type theorems for primes with a missing digit in their b-adic expansion for some large positive integer b. The proof is based on the circle method, which relies on the Fourier structure of the integers with a missing digit and the exponential sums over primes in arithmetic progressions. Combining our results with the semi-linear sieve, we obtain an upper bound and a lower bound of the correct order of magnitude for the number of primes of the form p=1+m^2+n^2 with a missing digit in a large odd base b.

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In many fields of science, engineering, and economics large amounts of data are stored and there is a need to analyze these data in order to extract information for various purposes. Data mining is a general concept involving different tools for performing this kind of analysis. The development of mathematical models and efficient algorithms is of key importance. In this thesis we discuss algorithms for the reduced rank regression problem and algorithms for the computation of the best multilinear rank approximation of tensors. The first two papers deal with the reduced rank regression problem, which is encountered in the field of state-space subspace system identification. More specifically the problem is \[ \min_{\rank(X) = k} \det (B - X A)(B - X A)\tp, \] where $A$ and $B$ are given matrices and we want to find $X$ under a certain rank condition that minimizes the determinant. This problem is not properly stated since it involves implicit assumptions on $A$ and $B$ so that $(B - X A)(B - X A)\tp$ is never singular. This deficiency of the determinant criterion is fixed by generalizing the minimization criterion to rank reduction and volume minimization of the objective matrix. The volume of a matrix is defined as the product of its nonzero singular values. We give an algorithm that solves the generalized problem and identify properties of the input and output signals causing a singular objective matrix. Classification problems occur in many applications. The task is to determine the label or class of an unknown object. The third paper concerns with classification of handwritten digits in the context of tensors or multidimensional data arrays. Tensor and multilinear algebra is an area that attracts more and more attention because of the multidimensional structure of the collected data in various applications. Two classification algorithms are given based on the higher order singular value decomposition (HOSVD). The main algorithm makes a data reduction using HOSVD of 98--99 \% prior the construction of the class models. The models are computed as a set of orthonormal bases spanning the dominant subspaces for the different classes. An unknown digit is expressed as a linear combination of the basis vectors. The resulting algorithm achieves 5\% in classification error with fairly low amount of computations. The remaining two papers discuss computational methods for the best multilinear rank approximation problem \[ \min_{\cB} \| \cA - \cB\| \] where $\cA$ is a given tensor and we seek the best low multilinear rank approximation tensor $\cB$. This is a generalization of the best low rank matrix approximation problem. It is well known that for matrices the solution is given by truncating the singular values in the singular value decomposition (SVD) of the matrix. But for tensors in general the truncated HOSVD does not give an optimal approximation. For example, a third order tensor $\cB \in \RR^{I \x J \x K}$ with rank$(\cB) = (r_1,r_2,r_3)$ can be written as the product \[ \cB = \tml{X,Y,Z}{\cC}, \qquad b_{ijk}=\sum_{\lambda,\mu,\nu} x_{i\lambda} y_{j\mu} z_{k\nu} c_{\lambda\mu\nu}, \] where $\cC \in \RR^{r_1 \x r_2 \x r_3}$ and $X \in \RR^{I \times r_1}$, $Y \in \RR^{J \times r_2}$, and $Z \in \RR^{K \times r_3}$ are matrices of full column rank. Since it is no restriction to assume that $X$, $Y$, and $Z$ have orthonormal columns and due to these constraints, the approximation problem can be considered as a nonlinear optimization problem defined on a product of Grassmann manifolds. We introduce novel techniques for multilinear algebraic manipulations enabling means for theoretical analysis and algorithmic implementation. These techniques are used to solve the approximation problem using Newton and Quasi-Newton methods specifically adapted to operate on products of Grassmann manifolds. The presented algorithms are suited for small, large and sparse problems and, when applied on difficult problems, they clearly outperform alternating least squares methods, which are standard in the field.

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