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Molecular Approaches to Photochemical Solar Energy Conversion : Towards Synthetic Catalysts for Water Oxidation and Proton ReductionEilers, Gerriet January 2007 (has links)
A molecular system capable of photoinduced water splitting is an attractive approach to solar energy conversion. This thesis deals with the functional characterization of molecular building blocks for the three principal functions of such a molecular system: Photoinduced accumulative charge separation, catalytic water oxidation, and catalytic proton reduction. Systems combining a ruthenium-trisbipyridine photosensitizer with multi-electron donors in form of dinuclear ruthenium or manganese complexes were investigated in view of the rate constants of electron transfer and excited state quenching. The kinetics were studied in the different oxidation states of the donor unit by combination of electrochemistry and time resolved spectroscopy. The rapid excited state quenching by the multi-electron donors points to the importance of redox intermediates for efficient accumulative photooxidation of the terminal donor. The redox behavior of manganese complexes as mimics of the water oxidizing catalyst in the natural photosynthetic reaction center was studied by electrochemical and spectroscopic methods. For a dinuclear manganese complex ligand exchange reactions were studied in view of their importance for the accumulative oxidation of the complex and its reactivity towards water. With the binding of substrate water, multiple oxidation in a narrow potential range and concomitant deprotonation of the bound water it was demonstrated that the manganese complex is capable of mimicking multiple aspects of photosynthetic water oxidation. A dinuclear iron complex was investigated as biomimetic proton reduction catalyst. The complex structurally mimics the active site of the iron-only hydrogenase enzyme and was designed to hold a proton on the bridging ligand and a hydride on the iron centers. Thermodynamics and kinetics of the protonation reactions and the electrochemical behavior of the different protonation states were studied in view of their potential catalytic performance.
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Seleno-diamminoacidi Redox con attività GPx nello studio del danno ossidativo indotto da Aflatossine / Redox, GPx mimic seleno-diamino acids in the study of oxidative damage induced by aflatoxins.NUCCI, ADA 23 February 2012 (has links)
La contaminazione da micotossine può coinvolgere tutti i comparti della filiera agroalimentare e rappresenta a tutti gli effetti un potenziale di perdita economica.
Il settore zootecnico è particolarmente esposto alle ricadute della contaminazione, in termini di costi sanitari per gli effetti cronici sulla salute animale conseguenti all’esposizione alle micotossine.
La prevenzione in campo mediata da appropriate tecniche agronomiche rappresenta, per quanto ovvio, la più importante strategia per ridurre la contaminazione dei mangimi. Un approccio completamente differente è quello che si basa sulla possibilità di ridurre gli effetti delle tossine sull’animale, modificando la sua alimentazione attraverso l’integrazione nutrizionale di opportuni agenti chemiopreventivi.
Numerose sono le specie chimiche, di origine naturale o sintetica, che hanno dimostrato una efficacia chemiopreventiva del danno ossidativo indotto da micotossine ed emergono per la loro efficacia il selenio e i suoi composti organici ed inorganici.
L’azione antineoplastica del selenio è nota da molto tempo e ha trovato conferme in numerosi studi epidemiologici che indicano una relazione inversa tra assunzione di selenio con la dieta e rischio di sviluppo di una patologia neoplastica.
Questa tesi di dottorato ha avuto come obiettivo la progettazione, la sintesi e lo studio di composti diamminoacidici contenenti un atomo di calcogeno (selenio o zolfo), mimici dalla glutatione perossidasi (GPx) e auspicabilmente attivi nel contrasto del danno ossidativo indotto dall’aflatossina B1 (AFB1).
Le specie diamminoacidiche sintetizzate appartengono alla classe dei Sec-derivati, ovvero sono costitute da un residuo di L-selenocisteina (o L-cisteina) a cui è legato attraverso l’atomo di calcogeno un altro L-amminoacido. Alla porzione calcogenica, che rappresenta il sito redox, sono stati infatti ancorati rispettivamente un residuo di L-prolina modificata e un residuo di L-leucina.
Al termine delle fasi di sintesi e caratterizzazione chimico-fisica dei calco-diamminoacidi è stata intrapresa una serie di indagini biochimiche in collaborazione con due distinti laboratori in Germania. I risultati ottenuti hanno permesso di dimostrare che alcuni Sec-derivati sono in grado di ridurre i perossidi attraverso un meccanismo catalitico che mima l’attività della GPx. Essi sembrano inoltre evidenziare che il “meccanismo antiossidante” sia mediato sostanzialmente dall’attività GPx mentre non sono particolarmente attivi meccanismi di radical scavenging né di puro trasferimento elettronico.
Alcuni dei Sec-derivati sintetizzati sono stati oggetto di un’indagine cellulare preliminare volta a verificare una eventuale effettiva azione protettiva dei calco-diamminoacidi verso il danno cellulare indotto da AFB1. Le indagini sono state effettuate adoperando una linea cellulare HepG2.
I dati ottenuti, nel loro insieme, hanno mostrato che i calco-diamminoacidi esaminati sono di per sé caratterizzati da una notevole attività biologica. In particolare, alla concentrazione più elevata utilizzata (100 µM), alcuni di essi hanno mostrato interessanti proprietà citoprotettive contro il danno indotto da AFB1. L’efficacia è paragonabile, e in qualche caso superiore, a quella riscontrabile per il composto di riferimento, la Se-metil-selenocisteina, principale forma di selenio organico che è naturalmente presente in specie vegetali quali Allium Sativum e Brassica juncea. / Mycotoxin contamination may involve all fields of the food agricultural chain and might potentially determine economic losses. In particular, the livestock sector is at risk of health costs, as a consequence of chronic diseases induced by mycotoxin exposure.
It is obvious, although actual, that the mycotoxin contamination should be controlled on the field by a series of suitable agriculture practices in order to minimize the mycotoxin formation in feeds.
Recently, dietary strategies (antioxidant compounds, medicinal herbs, plant extracts) to counteract the effects of mycotoxins have attracted considerable attention.
Chemoprevention refers to the use of naturally occuring and/or synthetic chemicals to inhibit the development of mycotoxin induced chronic diseases. Selenium and its organic and inorganic compounds, have emerged as outstanding chemoprevention agents.
Selenium antineoplastic properties have been well documented through the last decades, being supported by several epidemiological evidences on the association between selenium intake and the risk for some kinds of human/animal cancers.
This PhD thesis was focussed on design, synthesis and study of a family of chalcogenic diamino acids (containing either selenium or sulfur), GPx mimics and potentially active to reduce the oxidative damage induced by aflatoxin B1 (AFB1).
The diamino acids synthesized belong to the family of Sec-derivatives and consist of L-selenocysteine (or L-cysteine) linked through the calchogen atom to either a L-proline or a L-leucine moiety.
The GPx-like catalytic activity of the various compounds was confirmed using both thiophenol and GPx assays. Their possible radical-scavenging activity, and electron-donor reducing character as well, could be ruled out by suitable assays.
The cytoprotective capacity exhibited by several of the compounds synthesized was investigated in HepG2 cells by MTS assays. The results indicated that all the chalcogenic diamino acids tested had a strong biological activity.
In particular, the pre-treatment of the test cells with two Sec-derivatives, employed at higher doses (100 µM), led to a protective effect on cell toxicity, lowering the AFB1-induced cell mortality, and this efficacy is comparable with that of the reference Se-metil-selenocysteine, main source of organic selenium in plants such as Allium Sativum and Brassica juncea.
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Problem decomposition by mutual information and force-based clusteringOtero, Richard Edward 28 March 2012 (has links)
The scale of engineering problems has sharply increased over the last twenty years. Larger coupled systems, increasing complexity, and limited resources create a need for methods that automatically decompose problems into manageable sub-problems by discovering and leveraging problem structure. The ability to learn the coupling (inter-dependence) structure and reorganize the original problem could lead to large reductions in the time to analyze complex problems. Such decomposition methods could also provide engineering insight on the fundamental physics driving problem solution.
This work forwards the current state of the art in engineering decomposition through the application of techniques originally developed within computer science and information theory. The work describes the current state of automatic problem decomposition in engineering and utilizes several promising ideas to advance the state of the practice.
Mutual information is a novel metric for data dependence and works on both continuous and discrete data. Mutual information can measure both the linear and non-linear dependence between variables without the limitations of linear dependence measured through covariance. Mutual information is also able to handle data that does not have derivative information, unlike other metrics that require it. The value of mutual information to engineering design work is demonstrated on a planetary entry problem. This study utilizes a novel tool developed in this work for planetary entry system synthesis.
A graphical method, force-based clustering, is used to discover related sub-graph structure as a function of problem structure and links ranked by their mutual information. This method does not require the stochastic use of neural networks and could be used with any link ranking method currently utilized in the field. Application of this method is demonstrated on a large, coupled low-thrust trajectory problem.
Mutual information also serves as the basis for an alternative global optimizer, called MIMIC, which is unrelated to Genetic Algorithms. Advancement to the current practice demonstrates the use of MIMIC as a global method that explicitly models problem structure with mutual information, providing an alternate method for globally searching multi-modal domains. By leveraging discovered problem inter-dependencies, MIMIC may be appropriate for highly coupled problems or those with large function evaluation cost. This work introduces a useful addition to the MIMIC algorithm that enables its use on continuous input variables. By leveraging automatic decision tree generation methods from Machine Learning and a set of randomly generated test problems, decision trees for which method to apply are also created, quantifying decomposition performance over a large region of the design space.
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Zahalená tvář / Covered faceČERNÁ, Pavlína January 2018 (has links)
The diploma thesis focuses on human emotions and monitors their effects on the individual from the psychological and physiognomic point of view. It focuses on the development of ancient theatre and the function of masks. It consists of two parts - theoretical and practical. The practical part presents a set of latex masks that interpret the work of Erving Goffman The Presentation of Self in Everyday Life.
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Replicando estratégias de trading sintéticas utilizando redes neuraisFonseca, Raul do Vale 20 August 2018 (has links)
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Previous issue date: 2018-08-20 / Este trabalho constrói estratégias de trading sistemáticas e sintéticas com o objetivo de procurar ferramentas para replicá-las. São testados três modelos de regressão: regressão linear, regressão logística e um tipo de redes neurais artificiais, o multilayer perceptron (MLP). Para comparar a performance das regressões foram usadas três métricas de desvio do valor verdadeiro: diferenças absolutas, diferenças absolutas discretizadas e acurácia. A MLP é mais bem sucedida que as regressões logística e linear ao replicar uma estratégia trend following que usa como parâmetros médias móveis simples. Tentou-se replicar estratégias mean reversion que usam como parâmetros desvios padrão e preços máximos e mínimos num período. Nesses casos não houve clara distinção entre qual regressão foi mais bem sucedida. A acurácia dos modelos ao tentar replicar as estratégias foi maior que o sorteio aleatório em todos os casos. / In this text, systematic trading strategies are manufactured with the goal of finding tools to replicate it. Three regression models are tested: linear regression, logistic regression and one type of artificial neural networks, the multilayer perceptron (MLP). Three measures of the true value deviation were used to compare the performance of the regressions: absolute differences, discretized absolute differences and accuracy. The MLP is best between the three models to replicate one type of trend following strategy that uses simple moving average as parameter. It was attempted to replicate mean reversion strategies that uses standard deviation, maximum and minimum prices of a period as parameters. In this cases, there was no outperforming model to replicate the strategies. The accuracy of the models were better than the random guess in every test.
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Reconhecimento de movimentos humanos para imitação e controle de um robô humanoide / Recognition of human motions for imitation and control of a humanoid robotFernando Zuher Mohamad Said Cavalcante 24 August 2012 (has links)
Em interações humano-robô ainda existem muitas limitações a serem superadas referentes à provisão de uma comunicação natural quanto aos sentidos humanos. A capacidade de interagir com os seres humanos de maneira natural em contextos sociais (pelo uso da fala, gestos, expressões faciais, movimentos do corpo) é um ponto fundamental para garantir a aceitação de robôs em uma sociedade de pessoas não especialistas em manipulação de engenhos robóticos. Outrossim, a maioria dos robôs existentes possui habilidades limitadas de percepção, cognição e comportamento em comparação com seres humanos. Nesse contexto, este projeto de pesquisa investigou o potencial da arquitetura robótica do humanoide NAO, no tocante à capacidade de realizar interações com seres humanos através de imitação de movimentos do corpo de uma pessoa e pelo controle do robô. Quanto a sensores, foi utilizado um sensor câmera não-intrusivo de profundidade incorporado no dispositivo Kinect. Quanto às técnicas, alguns conceitos matemáticos foram abordados para abstração das configurações espaciais de algumas junções/membros do corpo humano essas configurações foram capturadas por meio da utilização da biblioteca OpenNI. Os experimentos realizados versaram sobre a imitação e o controle do robô por meio da avaliação de vários usuários. Os resultados desses experimentos revelaram um desempenho satisfatório quanto ao sistema desenvolvido / In human-robot interactions there are still many restrictions to overcome regarding the provision of a communication as natural to the human senses. The ability to interact with humans in a natural way in social contexts (the use of speech, gestures, facial expressions, body movements) is a key point to ensure the acceptance of robots in a society of people not specialized in manipulation of robotic devices. Moreover, most existing robots have limited abilities of perception, cognition and behavior in comparison with humans. In this context, this research project investigated the potential of the robotic architecture of the NAO humanoid robot, in terms of ability to perform interactions with humans through imitation of body movements of a person and the robot control. As for sensors, we used a non-intrusive sensor depth-camera built into the device Kinect. As to techniques, some mathematical concepts were discussed for abstraction of the spatial configurations of some joints/members of the human body these configurations were captured through the use of the OpenNI library. The performed experiments were about imitation and the control of the robot through the evaluation of various users. The results of these experiments showed a satisfactory performance for the developed system
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The Development of an Optimized System of Narcotic and Explosive Contraband Mimics for Calibration and Training of Biological DetectorsMacias, Michael S 27 May 2009 (has links)
Current commercially available mimics contain varying amounts of either the actual explosive/drug or the chemical compound of suspected interest by biological detectors. As a result, there is significant interest in determining the dominant chemical odor signatures of the mimics, often referred to as pseudos, particularly when compared to the genuine contraband material. This dissertation discusses results obtained from the analysis of drug and explosive headspace related to the odor profiles as recognized by trained detection canines. Analysis was performed through the use of headspace solid phase microextraction in conjunction with gas chromatography mass spectrometry (HS-SPME-GC-MS). Upon determination of specific odors, field trials were held using a combination of the target odors with COMPS. Piperonal was shown to be a dominant odor compound in the headspace of some ecstasy samples and a recognizable odor mimic by trained detection canines. It was also shown that detection canines could be imprinted on piperonal COMPS and correctly identify ecstasy samples at a threshold level of approximately 100ng/s. Isosafrole and/or MDP-2-POH show potential as training aid mimics for non-piperonal based MDMA. Acetic acid was shown to be dominant in the headspace of heroin samples and verified as a dominant odor in commercial vinegar samples; however, no common, secondary compound was detected in the headspace of either. Because of the similarities detected within respective explosive classes, several compounds were chosen for explosive mimics. A single based smokeless powder with a detectable level of 2,4-dinitrotoluene, a double based smokeless powder with a detectable level of nitroglycerine, 2-ethyl-1-hexanol, DMNB, ethyl centralite and diphenylamine were shown to be accurate mimics for TNT-based explosives, NG-based explosives, plastic explosives, tagged explosives, and smokeless powders, respectively. The combination of these six odors represents a comprehensive explosive odor kit with positive results for imprint on detection canines. As a proof of concept, the chemical compound PFTBA showed promise as a possible universal, non-target odor compound for comparison and calibration of detection canines and instrumentation. In a comparison study of shape versus vibration odor theory, the detection of d-methyl benzoate and methyl benzoate was explored using canine detectors. While results did not overwhelmingly substantiate either theory, shape odor theory provides a better explanation of the canine and human subject responses.
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Generation of a replication-competent simian-human immunodeficiency virus, the neutralization sensitivity of which can be enhanced in the presence of a small-molecule CD4 mimic / 低分子CD4 mimic存在下で中和感受性が増強される性質を持つサルヒト免疫不全ウイルスの作製Otsuki, Hiroyuki 24 March 2014 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第18186号 / 医科博第51号 / 新制||医科||4(附属図書館) / 31044 / 京都大学大学院医学研究科医科学専攻 / (主査)教授 小柳 義夫, 教授 松岡 雅雄, 教授 朝長 啓造 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
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Predicting Chronic Kidney Disease using a multimodal Machine Learning approachMishra, Aakruti, Puthiyandi, Navaneeth January 2023 (has links)
Chronic Kidney Disease (CKD) is a common and dangerous health condition that requires early detection and treatment to be effective. Current diagnostic methods are time-consuming and expensive. In this research, we hope to construct a predictive model for CKD utilizing a combination of time series and static variables for early detection of CKD. In this study, we investigate the influence of multimodal approach by combining the predictions from multiple models that utilize different modalities. The ROCKET method is utilized for classification using time series features, whilst the Random Forest approach is employed for static data. XGBoost has been utilized to gain information about feature importance among labs and demographics-comorbidities data. In this study, we use the MIMIC-III database, adopting various strategies to handle data and class imbalance, such as stratification, balancing techniques, and backwards and forward fill for missing value imputation. The evaluation metrics for CKD and non-CKD class labels include precision, recall, F1, and accuracy. Our findings show that aggregating time series data produce contrasting results for labs compared to vitals data. We also addressed the significance of the different demographic, comorbidities and lab events features. The findings indicate that a multimodal approach did not show significant advantages over individual models when the individual models performed suboptimal. The study also found that Ethnicity is more significant than age and gender in predicting CKD. Furthermore, the study revealed some significant features from lab events and comorbidities. The study also provides some recommendations for future work to explore the potential of a multimodal approach further.
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An Automated Discharge Summary System Built for Multiple Clinical English Texts by Pre-trained DistilBART ModelAlaei, Sahel January 2023 (has links)
The discharge summary is an important document, summarizing a patient’s medical information during their hospital stay. It is crucial for communication between clinicians and primary care physicians. Creating a discharge sum- mary is a necessary task. However, it is time-consuming for physicians. Using technology to automatically generate discharge summaries can be helpful for physicians and assist them in concentrating more on the patients than writing clinical summarization notes and discharge summaries. This master’s thesis aims to contribute to the research of building a transformer-based model for an automated discharge summary with a pre-trained DistilBART language model. This study plans to answer this main research question: How e↵ective is the pre-trained DistilBART language model in predicting an automated discharge summary for multiple clinical texts? The research strategy used in this study is experimental. the dataset is MIMIC- III. To evaluate the e↵ectiveness of the model, ROUGE scores are selected. The result of this model is compared with the result of the baseline BART model, which is implemented on the same dataset in the other recent research. This study regards multiple document summarization as the process of combining multiple inputs into a single input, which is then summarized. The findings indicate an improvement in ROUGE-2 and ROUGE-Lsum in the DistilBART model in comparison with the baseline BART model. However, one important limitation was computational resource constraint. The study also provides eth- ical considerations and some recommendations for future works.
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