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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Bountiful mind : memory, cognition and knowledge acquisition in Plato's Meno

Beaugrand, Selina January 2016 (has links)
The Meno has traditionally been viewed as "one of Plato's earliest and most noteworthy forays into epistemology." In this dialogue, and in the course of a discussion between Socrates and his young interlocutor, Meno, about the nature of virtue and whether it can be taught, “Meno raises an epistemological question unprecedented in the Socratic dialogues.” This question - or rather, dilemma - has come to be known in the philosophical literature as Meno’s Paradox of Inquiry, due its apparently containing an easy-to-detect equivocation of the word ‘know’. Immediately after the paradox, and in an apparent response to it, Socrates recounts a myth: a story told by priests and priestesses about the pre-natal existence and immortality of the soul. From this this myth, Socrates concocts the infamous theory of recollection – a theory according to which the soul has acquired knowledge of everything before it was born, while in a disincarnate state. According to the traditional reading of Meno’s paradox, this theory constitutes Plato’s response to it. The traditional reading has come under fire in recent years by advocates of the epistemological reading (ERM), who argue that the theory of recollection is not Plato’s intended response to the paradox. Instead, they suggest, Plato’s distinction between true belief and knowledge – which appears towards the end of the dialogue – is sufficient for solving the paradox; and as such, it ought to be read as Plato’s response to it. In this thesis, I argue against ERM’s claim that a mere epistemological distinction is all it takes to solve the paradox. To do so, I explore the metaphysics of change in Plato’s ontology. From this, I appeal to our everyday notion of ‘memory’ in order to show that Meno’s paradox, in fact, contains a hidden-premise, which when laid bare, reveals two distinct challenges contained within the argument: a superficial one, and a deeper one. I argue that although it appears at first blush as though the former could easily be dismissed as an equivocation, to which the epistemological distinction between belief and knowledge could provide an answer, the latter cannot. This is because the deeper challenge threatens the very preconditions of knowledge itself – that is to say, it renders cognition impossible – and, as such, it cancels out any effort to provide an epistemological response to the superficial challenge. Hence, unless the deeper-level challenge is satisfactorily disarmed, both challenges remain unanswered. I argue that although the major motivation for the theory of recollection in the Meno is indeed to provide an answer to scepticism about knowledge, nevertheless, it ought to be understood, first, as a theory of cognition – i.e. as a theory about the preconditions and atomic building blocks of knowledge – and not a theory of knowledge per se. This answer comes in the form of a radical theory of the mind and cognition – one that stands in stark opposition to our common-sense views about the mind: a view from which, Plato believed, the paradox arises. Drawing on recent debates between Nativists and Empiricists in the Cognitive Sciences, I argue that it was a great achievement of Plato’s to grasp that our common-sense view about the mind, and its concomitant process of learning, language acquisition and knowledge acquisition, might in fact be at the very root of scepticism about our ability to engage in meaningful philosophical practice, and our ability to acquire objective knowledge – especially, objective moral knowledge. The Meno’s paradox, then – so I contend - is not a puzzle whose solution rests upon merely pointing to an epistemological distinction between true belief and knowledge, as advocates of ERM have suggested. Rather, it is a puzzle about cognition. More precisely, it is a puzzle that targets the rudimentary cognitive stages of initial cognition and truth-recognition - one whose solution entails offering an account of the mind that would make these elementary cognitive processes possible. Accordingly, Plato’s theory of recollection in the Meno ought to be read as an attempt to map the structure of the mind, and as such, to provide an account of cognition. In doing so, he intended to put forward a view about the preconditions of knowledge – the sort of preconditions without which language acquisition and knowledge acquisition would simply not be possible. With this theory, Plato has the beginnings of an argument against the kind of relativism and scepticism prevalent at his time. As such, a correct interpretation of the so-called paradox of inquiry (and Plato’s proposed solution to it via the theory of recollection) should approach it as a puzzle about mind and cognition – and not solely as an epistemological one, as it has previously been treated.
122

Appealing to intuitions

Langkau, Julia January 2013 (has links)
This thesis is concerned with the ontology, epistemology, and methodology of intuitions in philosophy. It consists of an introduction, Chapter 1, and three main parts. In the first part, Chapter 2, I defend an account of intuitions as appearance states according to which intuitions cannot be reduced to beliefs or belief-like states. I argue that an account of intuitions as appearance states can explain some crucial phenomena with respect to intuitions better than popular accounts in the current debate over the ontology of intuitions. The second part, Chapters 3 to 5, is a reply to Timothy Williamson's (2004, 2007) view on the epistemology and methodology of intuitions. The practice of appealing to the fact that we have an intuition as evidence from thought experiments has recently been criticised by experimental philosophers. Williamson argues that since thought experiments reliably lead to knowledge of the content of our intuition, we can avoid this criticism and the resulting sceptical threat by appealing to the content of the intuition. I agree that thought experiments usually lead to knowledge of the content of our intuition. However, I show that appealing to the fact that we have an intuition is a common and useful practice. I defend the view that for methodological reasons, we ought to appeal to the fact that we have an intuition as initial evidence from thought experiments. The third part, Chapter 6, is devoted to a paradigm method involving intuitions: the method of reflective equilibrium. Some philosophers have recently claimed that it is trivial and could even accommodate scepticism about the reliability of intuitions. I argue that reflective equilibrium is not compatible with such scepticism. While it is compatible with the view I defend in the second part of the thesis, more specific methodological claims have to be made.
123

Maximising expected value under axiological uncertainty : an axiomatic approach

Riedener, Stefan January 2015 (has links)
The topic of this thesis is axiological uncertainty - the question of how you should evaluate your options if you are uncertain about which axiology is true. As an answer, I defend Expected Value Maximisation (EVM), the view that one option is better than another if and only if it has the greater expected value across axiologies. More precisely, I explore the axiomatic foundations of this view. I employ results from state-dependent utility theory, extend them in various ways and interpret them accordingly, and thus provide axiomatisations of EVM as a theory of axiological uncertainty. Chapter 1 defends the importance of the problem of axiological uncertainty. Chapter 2 introduces the most basic theorem of this thesis, the Expected Value Theorem. This theorem says that EVM is true if the betterness relation under axiological uncertainty satisfies the von Neumann-Morgenstern axioms and a Pareto condition. I argue that, given certain simplifications and modulo the problem of intertheoretic comparisons, this theorem presents a powerful means to formulate and defend EVM. Chapter 3 then examines the problem of intertheoretic comparisons. I argue that intertheoretic comparisons are generally possible, but that some plausible axiologies may not be comparable in a precise way. The Expected Value Theorem presupposes that all axiologies are comparable in a precise way. So this motivates extending the Expected Value Theorem to make it cover less than fully comparable axiologies. Chapter 4 then examines the concept of a probability distribution over axiologies. In the Expected Value Theorem, this concept figures as a primitive. I argue that we need an account of what it means, and outline and defend an explication for it. Chapter 5 starts to bring together the upshots from the previous three chapters. It extends the Expected Value Theorem by allowing for less than fully comparable axiologies and by dropping the presupposition of probabilities as given primitives. Chapter 6 provides formal appendices.
124

Belief, rationality, and truth

Ziska, Jens Dam January 2015 (has links)
Modern philosophy is often said to privilege rationality over received wisdom, but to some extent this is an ideal which we pursue under a measure of uncertainty. It is not always obvious what rationality requires. Nor is it clear how rationality is to be traded against other ideals. This dissertation seeks to clarify both questions as they pertain to the rationality of belief. The choice of topic is apposite, since many argue that the case of belief illustrates that what is rational and what there is most reason to do is one and the same thing. In particular, so-called evidentialists often argue that to believe what the evidence indicates is both to believe rationally and to believe what one has most reason to believe, since (i) rationality consists in responding to reasons, and (ii) only evidence that p can be a reason to believe that p. My first objective is to challenge this thesis. I do so by arguing that the class of reasons that rationalise a belief does not coincide with the class of reasons there are to have the belief all things considered. To equate the two classes would be to conflate the psychological issue of how we respond to reasons with the ontological issue of what reasons there are. My case against evidentialism does not depend on pragmatism being true, however. Even if Pascal was wrong to claim that the expected benefit of believing can be a reason to believe, it does not follow that evidentialism is true. Some non-pragmatic form of anti-evidentialism may still be true. The latter half of the dissertation explores this possibility in greater detail. There I argue that there is at least one class of beliefs which is not subject to common evidentiary strictures. When we use practical reasoning to form intentions about what to do in the future, we typically also form beliefs about what we will do. Yet, those beliefs are not based on evidence about what we will do, I argue. Typically, we do not predict what we do based on what we intend to do. Nor should we. When it is up to us whether we will perform an action, our intentions do to not carry enough weight as evidence that we must use them to predict what we will do. In the last part of the dissertation, I use this point to elucidate how we acquire self-knowledge and how belief relates to truth.
125

Achieving the standard for the analytical scope and sensitivity of forensic toxicology urine testing in drug facilitated crime investigations via laminar flow tandem mass spectrometry

McManus, Kelsey Lynn 23 November 2021 (has links)
Drug-facilitated sexual assaults are a public health and safety concern. Liquid chromatography paired with tandem mass spectrometry is theoretically capable of detecting the scope of drugs commonly encountered in these types of cases. An analytical method was developed for the quantitative analysis of 40 drugs designated by Academy Standards Board 121 “Standard for the Analytical Scope and Sensitivity for Forensic Toxicological Testing of Urine in Drug Facilitated Crime” (ASB 121). The targeted analytes spanned a range of drug classes including antidepressants, antihistamines, barbiturates, benzodiazepines, cannabinoids, stimulants, and opioids. The final method utilized supported liquid extraction, followed by liquid chromatography tandem mass spectrometry with electrospray ionization in simultaneous positive and negative mode. Multiple reaction monitoring allowed quantification of analytes along with stable isotope internal standards. Validation parameters assessed included linearity, bias, precision, limit of detection, lower limit of quantitation, interference, and ion suppression or enhancement. The utilized sample preparation method was able to extract 36 of the 40 target analytes and the developed analytical method was able to detect and quantify all analytes to the sensitivities required by ASB 121.
126

Multiple Binding Sites for [<sup>125</sup>I]RTI-121 and Other Cocaine Analogs in Rat Frontal Cerebral Cortex

Boja, J. W., Carroll, F. I., Vaughan, R. A., Kopajtic, T., Kuhar, M. J. 01 September 1998 (has links)
In an effort to identify novel binding sites for cocaine and its analogs, we carried out binding studies with the high-affinity and selective ligand [125I]RTI-121 in rat frontal cortical tissue. Very low densities of binding sites were found. Saturation analysis revealed that the binding was to both high- and low-affinity sites. Pharmacological competition studies were carried out with inhibitors of the dopamine, norepinephrine, and serotonin transporters. The various transporter inhibitors inhibited the. binding of 15 pM [125I]RTI-121 in a biphasic fashion following a two-site binding model. The resultant data were complex and did not suggest a simple association with any single transporter. Correlational analysis supported the following hypothesis: [125I] RTI-121 binds to known transporters and not to novel sites; these include dopamine, norepinephrine, and serotonin transporters. Immunoprecipitation of transporters photoaffinity labeled with [125]RTI-82 and subsequent analysis of SDS-page gels revealed the presence of authentic dopamine transporters in these samples; displacement of the photoaffinity label occurred with a typical dopamine transporter pharmacology. These data are compatible with the binding properties of RTI- 121 and the presence of several known transporters in the tissue studied.
127

L'entrepreneuriat forestier autochtone : le cas de la communauté ilnu de Mashteuiatsh

Beaudoin, Jean-Michel 16 April 2018 (has links)
La participation des communautés autochtones à la foresterie est un enjeu important au Québec. Pour les communautés autochtones, le développement forestier représente des retombées économiques importantes qui peuvent permettre de réduire l’écart entre les conditions socioéconomiques de leur population et celles de la population non-autochtone. Conséquemment, la participation des autochtones à la foresterie a sensiblement augmenté au cours des dernières décennies. Le manque d’information actuellement disponible nuit toutefois aux efforts déployés pour soutenir et encourager les initiatives autochtones en foresterie. Afin de mettre en exergue certains facteurs qui facilitent ou qui limitent les initiatives entrepreneuriales autochtones en foresterie, cette étude explore le développement de l’entrepreneuriat forestier dans la communauté ilnu de Mashteuiatsh. Cette communauté est située dans la région du Saguenay-Lac-Saint-Jean. Le premier chapitre situe le projet dans le contexte forestier québécois. Le deuxième chapitre présente le portrait des entrepreneurs forestiers autochtones de cette communauté. Finalement, le troisième chapitre compare ces entrepreneurs autochtones à des entrepreneurs forestiers non-autochtones de la même région. Les résultats de notre étude montrent l’importance pour l’entrepreneur forestier autochtone du réseau social au sein de la communauté de Mashteuiatsh. Cette situation permet d’expliquer en partie les différences constatées lors de la comparaison des profils, des perceptions et des motivations des entrepreneurs forestiers de la communauté de Mashteuiatsh et d’un groupe d’entrepreneurs forestiers non-autochtones. Les entrepreneurs autochtones, contrairement à leurs homologues non-autochtones, semblent très optimistes quand à l’évaluation de leur sort actuel et avenir. / The participation of the First Nations in forestry is a fundamental issue in the province of Québec. For their part, First Nations are considering forestry as a lever to improve the socioeconomic conditions in their communities. Over the last decades, there has been an increasing participation of First Nations in the forestry sector. Unfortunately, little information is currently available on aboriginal community initiatives in regards to business creation. The main objective of this research is to identify key factors that favor or limit aboriginal business creation in forestry. This study first presents the development of forest entrepreneurship within the Ilnu community of Mashteuiatsh, located in the region of Saguenay-Lac-Saint-Jean. The first chapter situates this project in the broader context of Québec forestry. The second chapter draws a portrait of forestry entrepreneurs within this community. The third chapter compares these aboriginal forestry entrepreneurs to non-aboriginal forestry entrepreneurs from the same area. Ours results demonstrate the importance for the aboriginal forest entrepreneur of the social network of the Mashteuiatsh Ilnu community. This network contributes to the differences observed when comparing the portrait, the perceptions and motivations of forestry entrepreneurs within the Ilnu community of Mashteuiatsh to those of non-aboriginal forestry entrepreneurs. In addition, Aboriginal forest entrepreneurs seem more optimist than non-aboriginal entrepreneurs when evaluating they actual situation and future.
128

Spatial and temporal complexities in forest productivity-climate relationships within northern temperate and boreal forests of eastern Canada

Anyomi, Kenneth Agbesi 19 April 2018 (has links)
La productivité est influencée par des facteurs climatiques et non-climatiques temporaires ou permanents. Leurs effets varient dans le temps et dans l’espace et le fait d’assumer une sensibilité homogène de la productivité alors qu’elle est en fait hétérogène a des conséquences sur la capacité de prévision de la productivité forestière. Il existe des preuves des changements globaux, régionaux et locaux et la réponse en terme de croissance à ces variations dans la forêt boréale est diversifiée et dans certains cas contrastées. Il est donc nécessaire de surveiller constamment la croissance et la productivité et des études régionales sont donc nécessaires pour étudier les alternatives des procédures d'estimation de la productivité. Cette thèse a donc pour but de déterminer dans quelle mesure les changements dans le climat et les régimes de perturbations affecter la productivité du site dans les forêts boréales et tempérées septentrionales situées dans la province de Québec. Des données d’analyse de tiges ont été obtenues pour 32 peuplements dominés par le tremble dans un transect nord-sud couvrant 5 degrés de latitude, représentant un large gradient climatique avec différent dépôts du surface. La croissance en hauteur en temps réel y a été étudiée à l’aide du modèle de productivité de Plonski. Plus de 4000 placettes échantillons temporaires ont été obtenues dans des peuplements d'âges, de structures et de compositions différentes pour mesurer les effets rétroactifs de la végétation sur la productivité, qui résultent indirectement du climat et du sol. Le modèle de Pothier et Savard a ensuite été utilisé pour estimer l'indice de qualité de station du tremble dans des peuplements mélangés. Enfin, le dernier chapitre a utilisé le modèle aspécifique hauteur dominante-âge de Pothier et Auger. Les résultats du premier chapitre montrent que, dans les peuplements dominés par le tremble, la croissance en hauteur est surtout influencée par la somme annuelle des degrés-jours, avec un pouvoir prévisionnel aussi bon que celui obtenu avec des variables basées sur les processus. Un modèle qui suppose que certaines populations ont des réponses différentes au climat est meilleur, ce qui démontre que la sensibilité du tremble au climat n'est pas identique sur toute son aire de dispersion. Dans les peuplements mélangés, la structure du peuplement et la composition en espèces sont les principaux facteurs expliquant la productivité du tremble. Une interaction entre les facteurs du paysage et de la placette influence la productivité à l’échelle des placettes, suggérant qu'une approche de modélisation hiérarchique est plus appropriée. Enfin, puisque les changements de structure et de composition reflètent la dynamique de succession, il est déduit que les changements successionnels dominent la variabilité de la productivité dans les peuplements mélangés. Nos résultats semblent concorder avec l’idée fondamentale de l’existence d’une hétérogénéité (dans la productivité forestière) due aux interactions intra- et inter-specifiques qui produisent des structures capables de s’adapter dans le temps, comme le suggère le concept des systèmes adaptatifs complexes. / Forest productivity is driven by direct climatic and non-climatic factors which are transient or permanent in nature. Their effects vary through time and along spatial scales, thus assuming equal sensitivities across time and space where heterogeneous growth responses exist has consequences for the prediction of forest productivity. There is growing evidence of global changes, associated by rather diverse and in some cases contrasting changes in growth. It is necessary to constantly monitor growth and productivity and regional studies are therefore necessary to consider alternative productivity estimation procedures. This thesis was therefore aimed at determining to what extent global, regional and local changes in climate and disturbance regimes affect forest site productivity within eastern Canadian boreal and northern temperate forests located within the province of Québec. Stem analysis data was first obtained from 32 aspen dominated stands that spanned a 5-degree of latitude-wide transect representing a large climate gradient with different surficial deposit types in order to study real-time height growth. Plonki’s site index model calibrated from stem analysis data was used in estimating a height growth index for these 32 stands. Over 4000 temporary sample plots were also obtained from stands of varying age, structure and species compositional gradients in order to determine feedback effects of vegetation on productivity, which are indirect effects of climate and soil. A site index model calibrated from temporary sample plots (and currently used in Québec for growth and yield estimation) was used in estimating site index for mixed aspen stands. Finally, the last chapter of this thesis used an aspecific height-age relationship. Results of the first chapter show that within aspen dominated stands, height growth is mainly driven by the annual cumulative sum of growing degree days with an explanatory capacity as good as that of more complex processed-based variables. Also, aspen productivity in pure stands is better explained with a model that assumes that specific populations have different response functions to climate, demonstrating that climate sensitivity is not stable across a species’ geographic range. Within mixed species stands, stand structure and species composition are the major drivers of aspen productivity. Variability in productivity is better explained at the level of landscapes than stand-level. An interaction between landscape- and stand-level drivers influence stand-level productivity, suggesting that a hierarchical modelling approach is more appropriate than a single-level model. Since stand structural and compositional changes are dynamics that characterize stand succession, it is inferred that successional changes and not climate drive productivity in mixed stands, when measured with site index. Our results seem to concur with the fundamental idea of the existence of heterogeneity (in forest productivity) due to intra- and inter-specific interactions in a way that produces structures capable of adapting through time, as suggested by the concept of complex adaptive systems.
129

Reconstruction tridimensionnelle de scènes sous-marines à partir de séquences d’images acquises par des caméras acoustiques

Brahim, Naouraz 20 April 2018 (has links)
Depuis que les études des impacts des changements climatiques ont montré que le milieu marin pourrait être énormément fragilisé par la disparition de certaines espèces de sa faune et de sa flore, ainsi que par le vieillissement rapide de son infrastructure sous-marine, la recherche de systèmes d’observation robustes et continus est classée parmi les sujets de recherche les plus prioritaires des scientifiques. Généralement, l’observation de l’environnement et l’inspection des infrastructures sous-marines se font au moyen des capteurs imageurs tels que les capteurs optiques ou les systèmes acoustiques. Toutefois, ces outils souffrent de certaines limitations lors de leur utilisation. Les caméras optiques fournissent des données caractérisées par une bonne résolution permettant une interprétation facile des scènes observées mais aussi par des problèmes techniques lors de l’acquisition liés aux conditions du milieu marin (e.g. manque de visibilité) empêchant une observation continue du milieu. Les sonars traditionnels produisent aussi des images mais ils n’offrent pas de séquences d’images de haute cadence tels que les capteurs optiques, et leur utilisation est parfois contrainte dans les milieux portuaires et de faible profondeur. C’est pour pallier ces problèmes que les caméras acoustiques ont été conçues. Elles ont la capacité d’acquérir des séquences d’images multi-vues avec une haute cadence et de fonctionner dans des milieux très turbides. Néanmoins, ces caméras ne produisent que des images en 2D où l’élévation de la scène observée est inconnue. Or, une représentation 2D de l’environnement ne peut présenter qu’une partie des informations, elle n’est pas en mesure de représenter "fidèlement" le milieu où le phénomène est observé. Ceci n’est possible qu’à travers une représentation 3D. L’objectif de cette thèse est donc de développer une approche de reconstruction 3D de scènes sous-marines à partir de séquences d’images acquises par des caméras acoustiques. Pour ce faire, nous nous sommes inspirés du principe de la stéréovision pour une reconstruction 3D à partir de points saillants. Néanmoins, la géométrie et la nature bruitée des images acoustiques ne permettent pas une application directe du principe de la stéréovision. Ainsi nous proposons dans cette thèse, une méthodologie de reconstruction 3D qui répond aux problématiques posées par les images des caméras acoustiques. Elle se base, en première partie, sur la conception d'un processus d’extraction de points saillants pertinents sur lesquels, en deuxième partie, va pouvoir s'appuyer la reconstruction 3D de la scène observée. Pour la reconstruction 3D, nous proposons deux approches différentes : une approche curviligne et une approche volumique. Dans ces deux approches, l’algorithme d’optimisation SE-AMC issu de la famille des stratégies d’évolution intervient dans le calcul du mouvement de la caméra entre les images, la détermination de ce mouvement permettant par la suite, l'estimation des informations 3D. La performance de l’approche d’extraction de primitives ainsi que celle des approches de reconstruction 3D ont été évaluées: la première au travers de critères de bonne détection, de répétabilité et de bonne localisation et la deuxième au travers de la comparaison du mouvement et des informations 3D estimés avec des données réelles. / According to recent studies, climate change is having a significant impact on our marine environment inducing temperature increases, chemistry changes, ocean circulation influencing both population dynamics and underwater structure stability. Environmental change is thus a growing scientific concern requiring a regular monitoring of the evolution of underwater ecosystems with appropriate studies combined with accurate and relevant detailed information extraction and preservation. Tracking and modeling such changes in a marine environment is one of the current challenges for underwater exploration. The most common technique used to observe underwater environment, relies on vision-based systems either acoustical or optical. Optical cameras are widely used for acquiring images of the seafloor/underwater structures as they can provide information about the physical properties of the image that will enable the description of the observed scene (color, reflection, geometry). However, the range limitation and non-ideal underwater conditions (dark and turbid waters) make acoustic imaging the most reliable means of sight inside the underwater environment. Traditional sonar systems cannot provide an acoustic image sequences like optical cameras. To overcome those drawbacks, acoustic camera was built. They can produce real time high resolution underwater image sequences, with high refresh rate. Moreover, compared to optical devices, they can acquire acoustic images in turbid, deep and dark water making acoustic camera imaging a reliable means for observing underwater environment. However, although acoustic cameras can provide 2-D resolution of the order of centimeters, they do not resolve the altitude of observed scene. Thus they offer a 2D environment representation which provides incomplete information about the underwater environment. Hence, it would be very interesting to have a system which can provide height information as well as a high resolution. This is the purpose of this thesis where we developed a methodology that enables 3D reconstruction of underwater scenes using sequences of acoustic images. The proposed methodology is inspired from stereovision techniques that allow 3D information computation from image sequences. It consists of two main steps. In the first step, we propose an approach that enables the extraction of relevant salient points from several images. In the second step, two different methods have been proposed (curvilinear approach and volumetric approach) in order to reconstruct the observed scene using images acquired from different viewpoints. The Covariance Matrix Adaptation Evolution Strategy algorithm (SE-AMC) has been used to compute camera movement between images. This movement has been then used to retrieve 3D information. The methodology performances have been evaluated: feature extraction approach has been assessed using criteria of good detection, repeatability and good localization and 3D reconstruction approach has been assessed by comparison between estimated camera movement and 3D information with real data.
130

Facteurs influençant le nourrissage des oisillons et son observation en forêt boréale

Hachey, Marie-Hélène 18 April 2018 (has links)
Pour bien évaluer les tendances populationnelles des oiseaux forestiers, ainsi que les effets des pratiques forestières sur ceux-ci, il est essentiel d’estimer leur succès de nidification. Les méthodes indirectes d’estimation basées sur l’activité parentale permettent d’analyser la productivité des oiseaux sur des territoires plus vastes que les approches traditionnelles de suivi de nids. Cependant, certains facteurs influencent l’activité parentale et son observation, ce qui peut donner un portrait incomplet ou faussé du succès de nidification. J’ai étudié les facteurs influençant la fréquence de nourrissage et la probabilité d’observer le transport de nourriture chez neuf espèces d’oiseaux chanteurs (17 nids) de la Forêt Montmorency (Québec), à l’été 2010. La fréquence des visites au nid augmentait avec l’âge des oisillons et diminuait avec les précipitations. Le transport de nourriture se manifestait de moins en moins avec l’avancement de la matinée et avec la distance au nid. La température ambiante n’avait pas d’effet observable sur la fréquence de nourrissage ou la probabilité d’observer le transport de nourriture. Il n’existait pas de corrélation entre la fréquence de nourrissage et la probabilité d’observer le transport de nourriture. Les résultats obtenus indiquent que les facteurs influençant ces deux phénomènes diffèrent, suggérant entre eux des liens d’une complexité plus grande qu’attendue. Mots clés : nourrissage des oisillons, transport de nourriture, activité parentale, comportements parentaux, succès de nidification, succès reproducteur, indices de reproduction, facteurs influençant le nourrissage. / Estimating the nesting success of forest birds is essential to understand their population dynamics and their response to forestry practices. Indirect methods based on parental activity allow estimation on a larger scale than traditional nest monitoring. However, a number of factors can influence parental activity and its observation. Here, we studied factors influencing nestling feeding frequency and the probability of observing food transport by parents at Forêt Montmorency, a boreal forest located in southern Québec. Seventeen nests of nine different species were monitored during summer of 2010. Feeding frequency increased with nestling age and decreased with precipitation. Probability of observing food transport decreased throughout the morning and with distance to nest. Frequency of visits to the nest and probability of observing food transport were not influenced by ambient temperature, and were not correlated. Our results indicate that biotic and abiotic factors can influence feeding frequency and observation of food transport. However, the same factors have a different effect on each phenomenon, which suggests a complexity greater than expected in the relationship between feeding frequency and observation of food transport. Keywords : nestling provisioning, food transport, parental activity, nesting success, reproductive success, reproductive index, factors influencing provisioning.

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