Optimal transport for Latent variable models

Generative models are probabilistic models which aim at approximating the process by which a given dataset is generated. They are well suited to the unsupervised learning setup and constitute intuitive and powerful models providing an interpretable representation of the data. However, learning even simple generative models can be challenging in the traditional Maximum Likelihood framework, due to the inflexibility of the training objective used. Motivated by its topological properties, we will show in this thesis how methods based on Optimal Transport can overcome these difficulties and offer competitive alternatives. Firstly, we show that training generative models that combine both discrete and continuous latent variables can be significantly more effective when using Optimal Transport methods. Such intuitive models are highly motivated by the structure of many real-world datasets but remain hard to train with the most common likelihood-based method, often resulting in the collapse of the discrete latent variables. Secondly, we propose a novel approach based on Optimal Transport to training models with fully Markovian deep-latent hierarchies. Probabilistic models with deep latent-variable structures have powerful modelling capacity, but common approaches often fail to leverage deep-latent hierarchies without complex inference and optimisation schemes. Our method successfully leverages the whole hierarchy of the models and shows competitive generative performance while learning smooth latent manifolds through every layers of the latent hierarchy. Finally, we introduce a new training objective to improve the learning of interpretable and disentangled representation of the data. Our method achieves competitive disentanglement relative to state-of-the-art techniques whilst improving the reconstruction and generation performances of the models

Learning Disentangled Representations with the Wasserstein Autoencoder

Disentangled representation learning has undoubtedly benefited from objective function surgery. However, a delicate balancing act of tuning is still required in order to trade off reconstruction fidelity versus disentanglement. Building on previous successes of penalizing the total correlation in the latent variables, we propose TCWAE (Total Correlation Wasserstein Autoencoder). Working in the WAE paradigm naturally enables the separation of the total-correlation term, thus providing disentanglement control over the learned representation, while offering more flexibility in the choice of reconstruction cost. We propose two variants using different KL estimators and analyse in turn the impact of having different ground cost functions and latent regularization terms. Extensive quantitative comparisons on data sets with known generative factors shows that our methods present competitive results relative to state-of-the-art techniques. We further study the trade off between disentanglement and reconstruction on more-difficult data sets with unknown generative factors, where the flexibility of the WAE paradigm leads to improved reconstructions

Improving Gaussian mixture latent variable model convergence with Optimal Transport

Generative models with both discrete and continuous latent variables are highly motivated by the structure of many real-world data sets. They present, however, subtleties in training often manifesting in the discrete latent variable not being leveraged. In this paper, we show why such models struggle to train using traditional log-likelihood maximization, and that they are amenable to training using the Optimal Transport framework of Wasserstein Autoencoders. We find our discrete latent variable to be fully leveraged by the model when trained, without any modifications to the objective function or significant fine tuning. Our model generates comparable samples to other approaches while using relatively simple neural networks, since the discrete latent variable carries much of the descriptive burden. Furthermore, the discrete latent provides significant control over generation

Milestone – a selective herbicide for the control of important grasses and broadleaved weeds in winter oilseed rape

MilestoneTM herbicide contains the active substance propyzamide (500 g/L) and aminopyralid (5.3 g a.e./L) and is formulated as a suspension concentrate (SC). Registration for Milestone for the use in winter oilseed rape was granted in Germany in July 2014.The active substance propyzamide is well known from the product KerbTM FLO (containing 500 g/L propyzamide, suspension concentrate, SC) which is widely used in winter oilseed rape (WITTROCK et al., 2008). Aminopyralid is formulated in the commercial product Runway (clopyralid + picloram + aminopyralid). Milestone is applied with a use rate of 1.5 L/ha as a post-emergence herbicide from growth stage BBCH 14 of the crop at the beginning of November until February. Kerb FLO is applied with a use rate of 1.875 L/ha at the same timing.The efficacy of Milestone and Kerb FLO was tested in randomised and replicated plot trials in Germany, France and the United Kingdom. Milestone and Kerb FLO showed comparable and very high control levels against monocotyledonous species such as Alopecurus myosuroides, Apera spica-venti, Bromus species and volunteer cereals. Milestone shows a broader spectrum of activity vs. Kerb FLO against dicotyledonous weeds such as Matricaria chamomilla, Papaver rhoeas and Centaurea cyanus. The use of Milestone in dense crops (as the situation was in autumn 2014 for many areas in Germany) shows very high efficacy levels as well. The comparison of various application timings between end of October until beginning of December confirms the application date early November for best results.Milestone controls herbicide-resistant weed populations and can be considered an important part of a resistance management program not only in winter oilseed rape but as a component of an integrated weed management strategy in cropping systems. Milestone – ein selektives Herbizid zur Bekämpfung wichtiger Ungräser und Unkräuter in WinterrapsMilestoneTM enthält die beiden herbiziden Wirkstoffe Propyzamid (500 g/l) und Aminopyralid (5,3 g a.e./l) und ist als Suspensionskonzentrat (SC) formuliert. Die Zulassung in Deutschland für die Anwendung von Milestone in Winterraps wurde im Juli 2014 erteilt. Der Wirkstoff Propyzamid ist aus dem Produkt Kerb FLOTM1 (400 g/l Propyzamid, Suspensionskonzentrat, SC) im Winterraps bekannt (WITTROCK et al., 2008). Aminopyralid ist in dem Produkt Runway (Clopyralid + Picloram + Aminopyralid) enthalten.Mit einer Aufwandmenge von 1,5 l/ha erfolgt die Anwendung von Milestone im Nachauflauf in Winterraps ab Entwicklungsstadium BBCH 14 der Kultur von Anfang November bis Februar. Kerb FLO wird mit 1,875 l/ha ebenfalls zu diesem Termin eingesetzt.Die Wirkung von Milestone und Kerb FLO wurde in Parzellenversuchen in Deutschland, Frankreich und Großbritannien geprüft. Milestone und Kerb FLO zeigten in den Versuchen vergleichbare und sehr gute Wirkungsgrade gegen monokotyle Arten wie Alopecurus myosuroides, Apera spica-venti, Bromus-Arten oder Ausfallgetreide. Im Vergleich zu Kerb FLO weist Milestone jedoch ein wesentlich breiteres Wirkungsspektrum gegen dikotyle Unkräuter wie etwa Kamille-Arten, Klatschmohn oder Kornblume auf. Auch eine Anwendung des Produktes in überwachsenen Rapsbeständen (wie im Herbst 2014 häufig zu beobachten) zeigt sehr hohe und sichere Wirkungsgrade. Ein Vergleich unterschiedlicher Applikationstermine zwischen Ende Oktober und Anfang Dezember bestätigt den optimalen Anwendungstermin Anfang November. Milestone erfasst auch resistente Unkrautpopulationen auf Problemstandorten und ist damit ein wichtiger Baustein für ein erfolgreiches Anti-Resistenzmanagement, nicht nur im Raps, sondern im Rahmen der gesamten ackerbaulichen Fruchtfolge

Estudo prospectivo do trauma dento-alveolar no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo

PURPOSE: This prospective study evaluated the profile of patients with dentoalveolar trauma assisted at the emergency room of the Oral and Maxillofacial Trauma and Surgery Service at the Hospital das Clínicas, São Paulo University Medical School (Brazil). METHODS: A prospective study by a questionnaire applied during the first attendance of those patients, in a period of eight months. RESULTS: The collected data were statistically analyzed. It was observed that 4.7% of the patients that sought treatment at the Service had sustained dentoalveolar trauma and among these 74% were male. The most affected individuals were children aged 0 to 5 years and fall was the most prevalent etiologic factor. Avulsion and coronal/crown-root fractures were the most common types of dentoalveolar traumatic injures. As the age increases, the most common etiologic factors are traffic accidents and physical assault. CONCLUSION: The incidence of dentoalveolar trauma decreased with age and the main etiologic factors in adult patients were traffic accidents and physical assault.PROPOSIÇÃO: Avaliar o perfil dos pacientes, com traumatismo dento-alveolar, atendidos no Pronto-Socorro do Serviço de Cirurgia e Traumatologia Buco-Maxilo-Facial do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (Brasil). MÉTODOS: Foi realizado um estudo prospectivo, através de um questionário aplicado, durante o primeiro atendimento desses pacientes, em um período de oito meses. RESULTADOS: Os dados obtidos foram analisados estatisticamente e verificou-se que dos pacientes atendidos 4,7% apresentavam traumatismo dento-alveolar, e destes, 74% eram do gênero masculino; as crianças de 0 a 5 anos eram as mais acometidas, a etiologia mais comum foi a queda; e o tipos de traumas mais freqüentes foram a avulsão e fratura dental. A medida que a idade avança os fatores etiológicos mais comuns são os acidentes de trânsito e as agressões físicas. CONCLUSÃO: A incidência de trauma de dentoalveolar diminuiu com a idade e o principal fator etiologico nos pacientes adulto foi acidentes de tráfico e agressão física

Analyse des phases oxydees dans les aciers par decomposition thermique

SIGLEINIST T 75451;Non accessible / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Estudos sobre o psicoativo N,N-dimetiltriptamina (DMT) em Mimosa tenuiflora (Willd.) Poiret e em bebidas consumidas em contexto religioso

183 f.N,N-dimetiltriptamina ou DMT é um alcaloide indólico com acentuada ação psicoativa, presente em bebidas vegetais de origem indígena, como o vinho da jurema e a ayahuasca. Esses preparos vegetais são consumidos em rituais religiosos sincréticos criados no Brasil no início do século 20, hoje dispersos e em contínua expansão por todo o mundo. As bebidas são também utilizadas como droga de abuso, no contexto recreativo, principalmente, graças à fácil disponibilidade das fontes vegetais utilizadas nos seus preparos, oferecida pelo comércio virtual. Neste trabalho, foi proposto um estudo de caracterização do DMT, isolado e purificado a partir das cascas da M. tenuiflora (jurema-preta), envolvendo metodologias instrumentais de análise como ressonância magnética nuclear de hidrogênio e carbono (RMN de 1H e 13C), espectroscopia na região do infravermelho (IR) e espectrometria de massas (MS). O nível de pureza do padrão foi determinado por absorção no ultravioleta (UV), utilizando um padrão de triptamina. Na execução dos trabalhos iniciais, percebeu-se a possibilidade de existência de polimorfismo para o DMT, fato comprovado através de técnicas de análise calorimétrica (DSC) e difração de Raios X. A partir do padrão analítico desenvolvido, foram propostos dois métodos para a determinação de DMT em matrizes vegetais e nas bebidas utilizadas, como sacramento, em rituais religiosos de origem brasileira, ambos otimizados por meio de técnicas multivariadas. O método MSPD/GC-MS desenvolvido para a quantificação de DMT nas cascas de M. tenuiflora foi devidamente validado, apresentando excelentes figuras de mérito. Apresentou boa linearidade (r = 0,9962) e repetibilidade (CV < 7,4%), com limite de detecção de 0,12 mg g-1. Foram analisadas 24 amostras de cascas, nas quais se verificou a presença de DMT, em níveis de concentração entre 1,26 e 9,35 mg g-1. O segundo método, descreve os procedimentos para a determinação de DMT nas bebidas rituais, por HS-SPME/GC- MS. Foi realizado amplo estudo de validação. Boa precisão (CV < 8,6%) e excelente exatidão, com recuperações entre 71–109%. Os limites de detecção e quantificação foram 0,78 e 9,5 mg L-1, respectivamente, além de boa linearidade (1,56–300 mg L-1, r2 = 0,9975). A análise do efeito na resposta analítica, causado por pequenas variações nos parâmetros otimizados, revelou excelente robustez. O método validado foi aplicado na análise de amostras reais de ayahuasca (7) e vinho da jurema (5). Todas as amostras foram diluídas para análise. Verificou-se grande variabilidade entre as concentrações de DMT nas bebidas. Nas amostras de vinho da jurema, os níveis de DMT estiveram entre 0,1 e 1,81 g L-1. Nas amostras de ayahuasca, concentrações entre 0,17 e 1,14 g L-1. A análise de outras cinco amostras de vinho da jurema, preparadas em laboratório por diferentes procedimentos, e diluídas para os ensaios, revelou que o aquecimento não tem grande significância na quantidade de DMT extraído da planta, sendo mais importantes o baixo pH do líquido extrativo e a presença de etanol