866 resultados para Expectation Maximization
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En aquest treball es descriu l'ús de les mesures de semblança molecular quàntica (MSMQ) per a caracteritzar propietats i activitats biològiques moleculars, i definir descriptors emprables per a construir models QSAR i QSPR. L'estudi que es presenta consisteix en la continuació d'un treball recent, on es descrivien relacions entre el paràmetre log P i MSMQ, donant així una alternativa a aquest parimetre hidrofòbic empíric. L'actual contribució presenta una nova mesura, capaç d'estendre l'ús de les MSMQ, que consisteix en l'energia de repulsió electró-electró (Vee). Aquest valor, disponible normalment a partir de programari de química quàntica, considera la molècula com una sola entitat, i no cal recórrer a l'ús decontribucions de fragments. La metodologia s'ha aplicat a cinc tipus diferents de compostos on diferents propietats moleculars i activitats biològiques s'han correlacionat amb Vee com a únic descriptor molecular. En tots els casos estudiats, s'han obtingut correlacions satisfactòries.
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Malgrat la rellevància estratègica i el paper desestabilitzador de Corea del Nord a la regió econòmicament més dinàmica del món, la UE no compta amb cap estratègia clara per involucrar-se amb aquest país. Combinant tècniques d’anàlisi qualitatives i quantitatives, aquest treball pretén descobrir possibles contradiccions internes que impedeixin la definició d'una política exterior europea coherent i efectiva amb respecte a Corea del Nord, així com discrepàncies entre les percepcions d’actors interns de la UE i les d’actors externs. S'han detectat importants diferències d’expectatives i mancances en termes de coherència, tant entre les visions expressades pels actors interns com entre les opinions d’aquests actors i les dels futurs líders sudcoreans enquestats – diferències que fins i tot afecten la promoció dels drets humans
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Institutional and organizational variety is increasingly characterizing advanced economic systems. While traditional economic theories have focused almost exclusively on profit-maximizing (i.e., for-profit) enterprises and on publicly-owned organizations, the increasing relevance of non-profit organizations, and especially of social enterprises, requires scientists to reflect on a new comprehensive economic approach for explaining this organizational variety. This paper examines the main limitations of the orthodox and institutional theories and asserts the need for creating and testing a new theoretical framework, which considers the way in which diverse enterprises pursue their goals, the diverse motivations driving actors and organizations, and the different learning patterns and routines within organizations. The new analytical framework proposed in the paper draws upon recent developments in the theories of the firm, mainly of an evolutionary and behavioral kind. The firm is interpreted as a coordination mechanism of economic activity, and one whose objectives need not coincide with profit maximization. On the other hand, economic agents driven by motivational complexity and intrinsic, non-monetary motivation play a crucial role in forming firm activity over and above purely monetary and financial objectives. The new framework is thought to be particularly suitable to correctly interpret the emergence and role of nontraditional organizational and ownership forms that are not driven by the profit motive (non-profit organizations), mainly recognized in the legal forms of cooperative firms, non-profit organizations and social enterprises. A continuum of organizational forms ranging from profit making activities to public benefit activities, and encompassing mutual benefit organizations as its core constituent, is envisaged and discussed.
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Gut microbiota has recently been proposed as a crucial environmental factor in the development of metabolic diseases such as obesity and type 2 diabetes, mainly due to its contribution in the modulation of several processes including host energy metabolism, gut epithelial permeability, gut peptide hormone secretion, and host inflammatory state. Since the symbiotic interaction between the gut microbiota and the host is essentially reflected in specific metabolic signatures, much expectation is placed on the application of metabolomic approaches to unveil the key mechanisms linking the gut microbiota composition and activity with disease development. The present review aims to summarize the gut microbial-host co-metabolites identified so far by targeted and untargeted metabolomic studies in humans, in association with impaired glucose homeostasis and/or obesity. An alteration of the co-metabolism of bile acids, branched fatty acids, choline, vitamins (i.e., niacin), purines, and phenolic compounds has been associated so far with the obese or diabese phenotype, in respect to healthy controls. Furthermore, anti-diabetic treatments such as metformin and sulfonylurea have been observed to modulate the gut microbiota or at least their metabolic profiles, thereby potentially affecting insulin resistance through indirect mechanisms still unknown. Despite the scarcity of the metabolomic studies currently available on the microbial-host crosstalk, the data-driven results largely confirmed findings independently obtained from in vitro and animal model studies, putting forward the mechanisms underlying the implication of a dysfunctional gut microbiota in the development of metabolic disorders.
Information overload, choice deferral, and moderating role of need for cognition: Empirical evidence
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ABSTRACT Choice deferral due to information overload is an undesirable result of competitive environments. The neoclassical maximization models predict that choice avoidance will not increase as more information is offered to consumers. The theories developed in the consumer behavior field predict that some properties of the environment may lead to behavioral effects and an increase in choice avoidance due to information overload. Based on stimuli generated experimentally and tested among 1,000 consumers, this empirical research provides evidence for the presence of behavioral effects due to information overload and reveals the different effects of increasing the number of options or the number of attributes. This study also finds that the need for cognition moderates these behavioral effects, and it proposes psychological processes that may trigger the effects observed.
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Individual-as-maximizing agent analogies result in a simple understanding of the functioning of the biological world. Identifying the conditions under which individuals can be regarded as fitness maximizing agents is thus of considerable interest to biologists. Here, we compare different concepts of fitness maximization, and discuss within a single framework the relationship between Hamilton's (J Theor Biol 7: 1-16, 1964) model of social interactions, Grafen's (J Evol Biol 20: 1243-1254, 2007a) formal Darwinism project, and the idea of evolutionary stable strategies. We distinguish cases where phenotypic effects are additive separable or not, the latter not being covered by Grafen's analysis. In both cases it is possible to define a maximand, in the form of an objective function phi(z), whose argument is the phenotype of an individual and whose derivative is proportional to Hamilton's inclusive fitness effect. However, this maximand can be identified with the expression for fecundity or fitness only in the case of additive separable phenotypic effects, making individual-as-maximizing agent analogies unattractive (although formally correct) under general situations of social interactions. We also feel that there is an inconsistency in Grafen's characterization of the solution of his maximization program by use of inclusive fitness arguments. His results are in conflict with those on evolutionary stable strategies obtained by applying inclusive fitness theory, and can be repaired only by changing the definition of the problem.
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Abstract The neo-liberal capitalist ideology has come under heavy fire with anecdotal evidence indicating a link between these same values and unethical behavior. Academic institutions reflect social values and act as socializing agents for the young. Can this explain the high and increasing rates of cheating that currently prevail in education? Our first chapter examines the question of whether self-enhancement values of power and açhievement, the individual level equivalent of neo-liberal capitalist values, predict positive attitudes towards cheating. Furthermore, we explore the mediating role of motivational factors. Results of four studies reveal that self-enhancement value endorsement predicts the adoption of performance-approach goals, a relationship mediated by introjected regulation, namely desire for social approval and that self-enhancement value endorsement also predicts the condoning of cheating, a relationship mediated by performance-approach goal adoption. However, self-transcendence values prescribed by a normatively salient source have the potential to reduce the link between self-enhancement value endorsément and attitudes towards cheating. Normative assessment constitutes a key tool used by academic institutions to socialize young people to accept the competitive, meritocratic nature of a sociéty driven by a neo-liberal capitalist ideology. As such, the manifest function of grades is to motivate students to work hard and to buy into the competing ethos. Does normative assessment fulfill these functions? Our second chapter explores the reward-intrinsic motivation question in the context of grading, arguably a high-stakes reward. In two experiments, the relative capacity of graded high performance as compared to the task autonomy experienced in an ungraded task to predict post-task intrinsic motivation is assessed. Results show that whilst the graded task performance predicts post-task appreciation, it fails to predict ongoing motivation. However, perceived autonomy experienced in non-graded condition, predicts both post-task appreciation and ongoing motivation. Our third chapter asks whether normative assessment inspires the spirit of competition in students. Results of three experimental studies reveal that expectation of a grade for a task, compared to no grade, induces greater adoption of performance-avoidance, but not performance-approach, goals. Experiment 3 provides an explanatory mechanism for this, showing that reduced autonomous motivation experienced in previous graded tasks mediates the relationship between grading and adoption of performance avoidance goals in a subsequent task. The above results, when combined, provide evidence as to the deleterious effects of self enhancement values and the associated practice of normative assessment in school on student motivation, goals and ethics. We conclude by using value and motivation theory to explore solutions to this problem.
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We previously reported that nuclear grade assignment of prostate carcinomas is subject to a cognitive bias induced by the tumor architecture. Here, we asked whether this bias is mediated by the non-conscious selection of nuclei that "match the expectation" induced by the inadvertent glance at the tumor architecture. 20 pathologists were asked to grade nuclei in high power fields of 20 prostate carcinomas displayed on a computer screen. Unknown to the pathologists, each carcinoma was shown twice, once before a background of a low grade, tubule-rich carcinoma and once before the background of a high grade, solid carcinoma. Eye tracking allowed to identify which nuclei the pathologists fixated during the 8 second projection period. For all 20 pathologists, nuclear grade assignment was significantly biased by tumor architecture. Pathologists tended to fixate on bigger, darker, and more irregular nuclei when those were projected before kigh grade, solid carcinomas than before low grade, tubule-rich carcinomas (and vice versa). However, the morphometric differences of the selected nuclei accounted for only 11% of the architecture-induced bias, suggesting that it can only to a small part be explained by the unconscious fixation on nuclei that "match the expectation". In conclusion, selection of « matching nuclei » represents an unconscious effort to vindicate the gravitation of nuclear grades towards the tumor architecture.
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Introduction: Indications for arthrodesis of the first metatarsophalangeal joint (MTP1) are commonly arthrosis (hallux rigidus), rheumatoid arthritis, failed hallux valgus surgery, severe hallux valgus, infectious arthritis, fractures and neuroarthropathies. Many reports focus on technical and radiological issues but few studies emphasize the functional outcome considering daily activities, sports and expectation of the patient. Method: We retrospectively reviewed the patients who underwent MTP1-arthrodesis from 2002 to 2005 in our institution. Clinical and radiological results were assessed but we specially focussed on the functional outcome. Scoring systems used were the SF-12, EQ-5D, PASI, FFI and AOFAS (10 points given to MTP1 mobility) scales. Results: 61 of 64 consecutive patients were evaluated. Female to male ratio was 49:15, mean age at surgery was 67 years, the average follow up was 29 month. Even if radiological consolidation was incomplete in 18 patients, all patients had a clinically stable and rigid arthrodesis. Mean AOFAS score was 87 (24-100) points at follow up. The FFI was 5.91% (0-66%). Patient satisfaction was excellent in 37 patients (60%), good in 18 (30%), fair in 5(8%) and poor in1 (2%). EQ- 5D was 0.7 (0.4-1).40 patients (66%) estimated their cosmetic result as excellent, 15 (25%) as good, 4(6%) as fair and 2 (3%)as poor. 10 patients (16%) had no shoe wear limitation , 48 (79%) had to wear comfortable shoes and 3 (5%) needed orthopaedic wearing. Professionally 34 patients (56%) had better performances, 18 (26%) had no change and 9 (18%) had aggravation of their capacities but this was due to other health reasons. In sports, 16 patients (26%) had better performances, 35 patients (57%) no change and 10 (17%) were worse as consequence of other health problems for 7. Finally, 56 patients (92%) would recommend the operation and 5 (8%) would not. Conclusion: Experience of clinical practice suggests that the idea of fusing the first MTP joint is initially frequently disregarded by the patients because they fear to be limited by a rigid forefoot. Our results show, in fact, that this procedure can be proposed for numerous pathological situations with the perspective of good to excellent outcome in terms of function and quality of life in the majority of cases.
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Proactive career behaviors become increasingly important in today's career environment, but little is known about how and when motivational patterns affect individual differences. In a six-month longitudinal study among German university students (Study 1; N = 289) it was demonstrated that motivation in terms of "can do" (self-efficacy and context beliefs), "reason to" (autonomous career goals), and "energized to" (positive affect) significantly predicted career behaviors. Contrary to expectation, negative context beliefs had a positive effect when combined with other motivational states. Study 2 replicated and extended those results by investigating whether "can do" motivation mediates the effect of proactive personality and whether those effects are conditional upon the degree of career choice decidedness. We tested a moderated multiple mediation model with a unique sample of 134 German students, assessed three times, each interval being 6 weeks apart. The results showed that effects of proactivity were partially carried through higher self-efficacy beliefs but not context beliefs. Supporting a moderation model, indirect effects through self-efficacy beliefs were not present for students with very low decidedness.
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For single-user MIMO communication with uncoded and coded QAM signals, we propose bit and power loading schemes that rely only on channel distribution information at the transmitter. To that end, we develop the relationship between the average bit error probability at the output of a ZF linear receiver and the bit rates and powers allocated at the transmitter. This relationship, and the fact that a ZF receiver decouples the MIMO parallel channels, allow leveraging bit loading algorithms already existing in the literature. We solve dual bit rate maximization and power minimization problems and present performance resultsthat illustrate the gains of the proposed scheme with respect toa non-optimized transmission.
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Le travail d'un(e) expert(e) en science forensique exige que ce dernier (cette dernière) prenne une série de décisions. Ces décisions sont difficiles parce qu'elles doivent être prises dans l'inévitable présence d'incertitude, dans le contexte unique des circonstances qui entourent la décision, et, parfois, parce qu'elles sont complexes suite à de nombreuse variables aléatoires et dépendantes les unes des autres. Etant donné que ces décisions peuvent aboutir à des conséquences sérieuses dans l'administration de la justice, la prise de décisions en science forensique devrait être soutenue par un cadre robuste qui fait des inférences en présence d'incertitudes et des décisions sur la base de ces inférences. L'objectif de cette thèse est de répondre à ce besoin en présentant un cadre théorique pour faire des choix rationnels dans des problèmes de décisions rencontrés par les experts dans un laboratoire de science forensique. L'inférence et la théorie de la décision bayésienne satisfont les conditions nécessaires pour un tel cadre théorique. Pour atteindre son objectif, cette thèse consiste de trois propositions, recommandant l'utilisation (1) de la théorie de la décision, (2) des réseaux bayésiens, et (3) des réseaux bayésiens de décision pour gérer des problèmes d'inférence et de décision forensiques. Les résultats présentent un cadre uniforme et cohérent pour faire des inférences et des décisions en science forensique qui utilise les concepts théoriques ci-dessus. Ils décrivent comment organiser chaque type de problème en le décomposant dans ses différents éléments, et comment trouver le meilleur plan d'action en faisant la distinction entre des problèmes de décision en une étape et des problèmes de décision en deux étapes et en y appliquant le principe de la maximisation de l'utilité espérée. Pour illustrer l'application de ce cadre à des problèmes rencontrés par les experts dans un laboratoire de science forensique, des études de cas théoriques appliquent la théorie de la décision, les réseaux bayésiens et les réseaux bayésiens de décision à une sélection de différents types de problèmes d'inférence et de décision impliquant différentes catégories de traces. Deux études du problème des deux traces illustrent comment la construction de réseaux bayésiens permet de gérer des problèmes d'inférence complexes, et ainsi surmonter l'obstacle de la complexité qui peut être présent dans des problèmes de décision. Trois études-une sur ce qu'il faut conclure d'une recherche dans une banque de données qui fournit exactement une correspondance, une sur quel génotype il faut rechercher dans une banque de données sur la base des observations faites sur des résultats de profilage d'ADN, et une sur s'il faut soumettre une trace digitale à un processus qui compare la trace avec des empreintes de sources potentielles-expliquent l'application de la théorie de la décision et des réseaux bayésiens de décision à chacune de ces décisions. Les résultats des études des cas théoriques soutiennent les trois propositions avancées dans cette thèse. Ainsi, cette thèse présente un cadre uniforme pour organiser et trouver le plan d'action le plus rationnel dans des problèmes de décisions rencontrés par les experts dans un laboratoire de science forensique. Le cadre proposé est un outil interactif et exploratoire qui permet de mieux comprendre un problème de décision afin que cette compréhension puisse aboutir à des choix qui sont mieux informés. - Forensic science casework involves making a sériés of choices. The difficulty in making these choices lies in the inévitable presence of uncertainty, the unique context of circumstances surrounding each décision and, in some cases, the complexity due to numerous, interrelated random variables. Given that these décisions can lead to serious conséquences in the admin-istration of justice, forensic décision making should be supported by a robust framework that makes inferences under uncertainty and décisions based on these inferences. The objective of this thesis is to respond to this need by presenting a framework for making rational choices in décision problems encountered by scientists in forensic science laboratories. Bayesian inference and décision theory meets the requirements for such a framework. To attain its objective, this thesis consists of three propositions, advocating the use of (1) décision theory, (2) Bayesian networks, and (3) influence diagrams for handling forensic inference and décision problems. The results present a uniform and coherent framework for making inferences and décisions in forensic science using the above theoretical concepts. They describe how to organize each type of problem by breaking it down into its différent elements, and how to find the most rational course of action by distinguishing between one-stage and two-stage décision problems and applying the principle of expected utility maximization. To illustrate the framework's application to the problems encountered by scientists in forensic science laboratories, theoretical case studies apply décision theory, Bayesian net-works and influence diagrams to a selection of différent types of inference and décision problems dealing with différent catégories of trace evidence. Two studies of the two-trace problem illustrate how the construction of Bayesian networks can handle complex inference problems, and thus overcome the hurdle of complexity that can be present in décision prob-lems. Three studies-one on what to conclude when a database search provides exactly one hit, one on what genotype to search for in a database based on the observations made on DNA typing results, and one on whether to submit a fingermark to the process of comparing it with prints of its potential sources-explain the application of décision theory and influ¬ence diagrams to each of these décisions. The results of the theoretical case studies support the thesis's three propositions. Hence, this thesis présents a uniform framework for organizing and finding the most rational course of action in décision problems encountered by scientists in forensic science laboratories. The proposed framework is an interactive and exploratory tool for better understanding a décision problem so that this understanding may lead to better informed choices.
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AIMS/HYPOTHESIS: Epidemiological and experimental evidence suggests that uric acid has a role in the aetiology of type 2 diabetes. Using a Mendelian randomisation approach, we investigated whether there is evidence for a causal role of serum uric acid for development of type 2 diabetes. METHODS: We examined the associations of serum-uric-acid-raising alleles of eight common variants recently identified in genome-wide association studies and summarised this in a genetic score with type 2 diabetes in case-control studies including 7,504 diabetes patients and 8,560 non-diabetic controls. We compared the observed effect size to that expected based on: (1) the association between the genetic score and uric acid levels in non-diabetic controls; and (2) the meta-analysed uric acid level to diabetes association. RESULTS: The genetic score showed a linear association with uric acid levels, with a difference of 12.2 μmol/l (95% CI 9.3, 15.1) by score tertile. No significant associations were observed between the genetic score and potential confounders. No association was observed between the genetic score and type 2 diabetes with an OR of 0.99 (95% CI 0.94, 1.04) per score tertile, significantly different (p = 0.046) from that expected (1.04 [95% CI 1.03, 1.05]) based on the observed uric acid difference by score tertile and the uric acid to diabetes association of 1.21 (95% CI 1.14, 1.29) per 60 μmol/l. CONCLUSIONS/INTERPRETATION: Our results do not support a causal role of serum uric acid for the development of type 2 diabetes and limit the expectation that uric-acid-lowering drugs will be effective in the prevention of type 2 diabetes.
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This article challenges the notion of economic rationality as a criterion for explaining ethnic boundary maintenance. It offers an ethnographic analysis of inter-ethnic relations in the context of games (cockfights and game-fishing contests) in the island of Raiatea (French Polynesia). Although all players engage in the same basic gambling practices, money is differentially scaled and mobilized by the Tahitian and Chinese participants. Building on recent pragmatic approaches to rationality, it is shown that the players' rationalities differ not from the point of view of economic maximization, but only in so far as they participate in social relations at different scales.
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The purpose of this paper is to provide a translation into Spanish of a review articleabout genetically modified organisms (GMOs) entitled “Genetically ModifiedOrganisms (GMOs): Transgenic Crops and Recombinant DNA Technology” publishedby the well-known scientific journal Nature. In a world where English has become thelingua franca when it comes to transferring scientific knowledge and information, itmust be taken into account that not everyone—from scientist to the general public—hasa good enough command of English so that they can feel comfortable enough reading inthis language. Translators are consequently needed resulting from a great demand oftranslation activity into, for example, Spanish. This is the reason why the proposedSpanish translation is followed by a detailed analysis emphasizing the difficulties andproblems that characterize scientific—and also general—translation (i.e. terminology,syntax, semantics, pragmatics, and ideology), for which different approaches as how tosolve them are provided. On the basis of the analysis, it can be concluded thatexperience will be of much help to scientific translators, given that specificterminological knowledge and style requirements must always be born in mind whentranslating in this field. Moreover, this paper is intended to serve as a guide forTranslation students specializing in the field of science and the expectation is to helpthem make the right decisions when it comes to translating. However, it is clear that itcan only be thought of as an introduction that should be completed with further researchand documentation tasks in order to offer a complete reference tool: the ultimatehandbook of scientific translation.