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Avaliação do perfil oxidativo e da atividade de ectoenzimas em pacientes com neoplasia intra-epitelial cervical / Evaluation of oxidative stress profile and activity of ecto-enzymes in patients with cervical intraepithelial neoplasiaMaldonado, Paula Acosta 22 August 2008 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Uterine cancers are considered to be one of the most important malignant diseases of the female genital tract, preceded only by breast cancer. The tumor cells may produce oxidative disturbances as well as damage to the antioxidant system. Cancer may also induce alterations in blood coagulation, ranging anywhere from slight platelet activation to thrombus formation, which impair the quality of life of these patients. This study aimed to evaluate the influence of uterine cervix cancer and its treatments, such as conization and radiotherapy (RTX), on the possible development of thrombogenic processes, on the oxidative profile and on coagulation disorders. Variations in the oxidative profile were analyzed through the determination of parameters such as TBARS and protein carbonyl content and antioxidant defenses were determined from the activity of catalase and reduced glutathione (GSH). Thromboembolic disorders were evaluated by the activity of enzymes such as NTPDase, E-NPP and 5 -nucleotidase, since all of these are present in the platelet membrane, as well as the activity of ADA which has an important role in the degradation of adenosine, which in turn is known for possessing tumor promoting functions. The evaluation of oxidative and antioxidant parameters revealed that TBARS levels, protein carbonyl, GSH and the activity of catalase were enhanced in the non treated group when compared to the other groups. The increased levels of oxidants may reflect their enhanced production by tumor cells, since it is known that antioxidant levels are enhanced at the beginning of the neoplasic transformation in an attempt to neutralize the enhanced free radical production. As for the enzymes involved in the thrombogenic process, the results revealed a significant inhibition of NTPDase in groups treated for a long time ago by CNZ or RTX, when compared to the more recently treated groups and the control. The reduced ATP hydrolysis could be acting to prevent ADP formation, since this nucleotide is the main agent that promotes platelet aggregation. The reduced AMP hydrolysis in all the treated groups, may be a result of the reduced production of adenosine due to the effectiveness of the treatments. In the conization and RTX treated groups, E-NPP activity, both in serum and platelets, was reduced when compared to the control and non treated groups, which could be a reflection of reduced nucleotide degradation, due to the absence of tumor cells and, in turn, lower production of adenosine, which is a tumor promoting agent and is also the substrate for ADA. The probable absence of tumor cells due to the effectiveness of the treatments and the
reduced adenosine concentration may be responsible for the reduced ADA activity found in the same groups. The inhibition of enzymes such as E-NPP, 5 -nucleotidase and ADA in all the treated groups may suggest the role of these enzymes in sequentially controlling the concentrations of nucleotides in the extracellular environment. NTPDase appears to be more sensitive to changes caused by the passing of time after the end of the treatments. We may say that the surgery itself causes greater alterations in enzymes such as E-NPP, 5 -nucleotidase and ADA from platelets, because in the groups recently treated by CNZ these activities were enhanced as compared with the group recently treated by RTX, possibly as a result of platelet alteration, which would be responsible for the enzymatic alterations observed. NTPDase is more involved in the control of platelet aggregation and the enzymes 5`-nucleotidase, E-NPP and ADA are more involved in controlling adenosine concentrations. / Os carcinomas uterinos despontam como uma das doenças malignas mais importantes do trato genital feminino, precedido apenas pelo câncer de mama. As células tumorais podem originar distúrbios oxidativos, bem como prejuízo das defesas antioxidantes desses pacientes. O câncer também pode induzir alterações na coagulação sangüínea que vão desde uma pequena ativação plaquetária até a formação de trombos na circulação, os quais prejudicam a qualidade de vida desses pacientes. Este trabalho teve como objetivo avaliar a influência do carcinoma cervical uterino e de tratamentos como a conização (CNZ) e a radioterapia (RTX) sobre o possível desenvolvimento de processos trombogênicos, sobre o perfil oxidativo e sobre os distúrbios da coagulação. As variações no perfil oxidativo foram analisadas pela determinação de parâmetros como o conteúdo de TBARS e de proteína carbonil, e as defesas antioxidantes através da atividade da enzima catalase e dos níveis de glutationa reduzida (GSH). As desordens tromboembólicas foram analisadas pela determinação da atividade de enzimas como a NTPDase, a E-NPP e a 5 -nucleotidase, enzimas presentes na membrana plaquetária, bem como através da atividade da enzima ADA a qual tem a importante função na degradação da adenosina, que reconhecidamente desempenha funções promotoras de tumor. A avaliação dos parâmetros oxidativos e antioxidantes revelou que os níveis de TBARS, de proteína carbonil, de GSH e a atividade da enzima catalase estavam aumentados no grupo de pacientes não tratados em relação aos demais grupos. O aumentado nível de oxidantes pode ser reflexo de um aumento na sua produção pela célula tumoral. Os antioxidantes podem estar aumentados possivelmente por estar no início da transformação neoplásica tumoral na tentativa de compensar o aumento da produção de espécies reativas. Com relação às enzimas envolvidas nos processos tromboembólicos, os resultados revelaram que ocorreu uma inibição significativa da enzima NTPDase nos grupos tratados há mais tempo tanto por CNZ quanto por RTX, em relação aos grupos tratados recentemente e em relação ao grupo controle. A reduzida hidrólise do ATP poderia estar atuando como forma de prevenção contra a formação do ADP, visto que este nucleotídeo é o principal agente promotor da agregação plaquetária. No caso da
enzima 5 -nucleotidase observamos uma reduzida hidrólise do AMP, em todos os grupos tratados, que pode ser o resultado da reduzida produção de adenosina pela efetividade dos tratamentos. Em todos os grupos tratados por CNZ e RTX a atividade da E-NPP, tanto em soro quanto em plaquetas, estava reduzida em relação ao grupo controle e ao grupo com neoplasia não-tratada, podendo ser o reflexo da reduzida degradação de nucleotídeos, pela ausência das células tumorais, formando menos adenosina, a qual é um agente promotor de tumor e também o substrato para a ADA. A ausência de células tumorais pela efetividade dos tratamentos e a reduzida concentração de adenosina, pode ser responsável pela reduzida atividade da ADA nos mesmos grupos. A inibição da atividade das enzimas E-NPP, 5 -nucleotidase e da ADA nos grupos tratados, pode sugerir o papel dessas enzimas no controle seqüencial das concentrações de nucleotídeos no meio extracelular. A enzima NTPDase parece ser um pouco mais sensível às mudanças provocadas pelo tempo transcorrido após o término dos tratamentos. Pode-se inferir também, que a cirurgia causa maiores alterações nas enzimas E-NPP, 5 -nucleotidase e ADA de plaquetas, pelo fato de que nos grupos tratados recentemente por CNZ estas atividades encontram-se aumentadas em relação grupo tratado recentemente por RTX. Sugere-se, com esses resultados, que há uma possível alteração nas plaquetas, causada pelo processo cirúrgico, o qual seria o responsável pelas modificações enzimáticas observadas e que os tratamentos foram efetivos em combater as células tumorais uma vez que, de uma maneira geral há uma inibição das atividades das enzimas em questão, e também devido ao fato de que os testes de coagulação, possíveis indicadores de trombose associada ao câncer, não demonstraram-se alterados. Corroborando estes achados os exames citopatológicos apresentaram alterações celulares compatíveis com a normalidade. A enzima NTPDase demonstra-se estar envolvida no controle da agregação plaquetária e as enzimas 5`-nucleotidase, E-NPP e ADA parecem estar mais envolvidas no controle dos níveis de adenosina. Palavras-chave: Câncer de útero, radioterapia, conização, estresse oxidativo, plaquetas, trombose, NTPDase, E-NPP, ADA.
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VARIABILIDADE NA PRODUÇÃO PRIMÁRIA LÍQUIDA EM MODELOS DE SUPERFÍCIE PARA SÍTIOS SUL-AMERICANOS / VARIABILITY IN ESTIMATED NET PRIMARY PRODUCTION FROM LAND SURFACE MODELS FOR SOUTH AMERICAN SITESSilveira, Marcos Corrêa 14 March 2013 (has links)
Programa de Apoio aos Planos de Reestruturação e Expansão das Universidades Federais / This study analyzes simulations of Net Primary Production (NPP) from 15 different landsurface
models (LSMs) and biomass pools from 6 different LSMs using meteorological
conditions measured at 8 sites from Large-Scale Biosphere-Atmosphere Experiment in
Amazonia (LBA) project as drivers. The models were not calibrated for the sites. The sites are
divided into four biome types: Evergreen Broadleaf Forests (4 sites); Deciduous Broadleaf
Forest (1 site); Savanna (1 site); Pasture/Agriculture (2 sites). The mean daily cycles, monthly
and annual means of NPP were intercompared and evaluated. There were considerable
differences among the NPP simulations, and some of these differences reached up to two
orders of magnitude in nocturnal values. Seasonality in dry periods of the NPP could be
observed in some models for all biome types. The annual mean NPP simulations from two
Evergreen Broadleaf Forests (K34 and K67 sites) were compared with the observations. In
general, the simulations by most models do not represent very well the observations; however,
the mean value from all simulations is able to represent the observed data. In general, models
that represented the Dynamic Vegetation Carbon Fluxes and Nitrogen Cycling Models (DVN)
were those that better represented the observed values, suggesting that a more specific
description of the vegetation dynamics capture, even without calibration, the carbon
exchanges with enough accuracy. The simulated biomass is also divergent between the
models, although the distribution of that biomass follows the expected patterns for each biome
type. Therefore, we believe that a model calibration can improve the simulations results. / Este estudo analisa simulações de Produção Primária Líquida (NPP) de 15 diferentes modelos
de superfície (LSMs) e reservatórios de biomassa de 6 diferentes LSMs usando condições
meteorológicas medidas em 8 sítios do projeto Large-Scale Biosphere-Atmosphere
Experiment in Amazônia (LBA) como forçantes. Os modelos não foram calibrados para os
sítios. Os sítios foram divididos em quatro tipos de biomas: Florestas de Folhas Largas
Sempre-Verdes (4 sítios); Florestas de Folhas Largas Decídua (1 sítio); Savana (cerrado, 1
sítio); Pasto/Agricultura (2 sítios). Os ciclos de NPP médios diários, mensais e anuais foram
intercomparados e avaliados. Existem diferenças consideráveis entre as simulações de NPP, e
algumas destas diferenças alcançaram até duas ordens de magnitude em valores noturnos.
Pôde ser observada sazonalidade de NPP em alguns modelos para todos os tipos de bioma. O
NPP médio anual simulado em duas Florestas Sempre-Verdes (sítios K34 e K67) foi
comparado com as observações. Em geral, as simulações da maior parte dos modelos não
representam muito bem as observações; entretanto, o valor médio de todas as simulações
consegue representar os dados observados. Em geral, modelos que representam a vegetação
dinâmica, fluxos de carbono e ciclo do nitrogênio (DVN) foram aqueles que melhor
representaram os valores observados, sugerindo que uma descrição mais específica da
dinâmica da vegetação pode capturar, mesmo sem calibração, as trocas de carbono com
suficiente precisão. A biomassa simulada é também divergente entre os modelos, embora a
distribuição dessa biomassa segue os padrões esperados para cada tipo de bioma. Logo,
acreditamos que uma calibração do modelo pode melhorar os resultados das simulações.
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Kolbalanser i boreal skog : Hur skog ska skötas för störst klimatnytta samt missuppfattningar hos elever gällande kolets kretslopp. / Carbon balance in boreal forests : Forest management for minimising climate impact and school pupils' misconceptions of the carbon cycle.Ulfsparre, Cecilia January 2020 (has links)
Koldioxidhalterna stiger i världen, vilket bidrar till global uppvärmning. Skogen har en viktig roll i klimatarbetet då stora mängder kol finns lagrad i skog och mark. Speciellt mycket kol finns i boreal skog, som bland annat finns i norra Sverige. Idag pågår en debatt huruvida det är mer fördelaktigt att behålla gammal skog som kolsänka, eller avverka den för att ge plats åt yngre träd. Syftet med litteraturstudien var att ge en klargörande bild över hur åldern på boreal skog påverkar ekosystemets kolbalans, genom att undersöka skogens kolupptagningshastighet samt möjlighet till kollagring. Studien visade att äldre skog har ett större totalt kollager, att medelåldrig skog har högst tillväxthastighet (nettoekosystemproduktion, NEP och nettoprimärproduktion, NPP) samt att NEP är negativ de första 10 åren. Studien visade på osäkerhet kring kolupptag i gamla skogar. Flera variabler, såsom substitution, störningar och biologisk mångfald är inte undersökta i studien och behövs tas i beaktning vid beslutsfattande. Trots detta, antyder litteraturstudien att det är fördelaktigt att låta gammal skog stå kvar som kolsänka, eftersom koldioxidutsläppen behöver minska snarast. Ytterligare ett syfte med studien var att kartlägga de missuppfattningar elever, i senare delen av skolan, har gällande kolets kretslopp. Studien visade på missuppfattningar gällande fotosyntes och respiration hos växter, nedbrytarnas roll samt sammanblandning av begrepp. För att åtgärda problemet kan uppgifter göras där atomer följs över olika nivåer, för att sätta processerna i sitt sammanhang. Stort fokus gällande missuppfattningarna ligger på fotosyntes och respiration och inga artiklar hittades gällande exempelvis det snabba, respektive långsamma, kretsloppet. Få studier är gjorda på svenska elever och då svensk kursplan lägger fokus på samband mellan olika nivåer kan missuppfattningarna vara i annorlunda i Sverige. Hur missuppfattningarna ser ut i svensk skola är föremål för vidare forskning. / The amount of carbon dioxide is rising in the atmosphere, which contributes, to global warming. Since large amounts of carbon are stored in forests, forests play an important part the efforts to improve the environment. Boreal forests, found in e.g. the northern part of Sweden, store especially large amounts of carbon. Today it is being debated whether it is more beneficial for the environment to keep old forests as a carbon sink, or to cut them down in order to make room for younger trees. The purpose of this literature study was to clarify how the age of the forest affects the carbon balance of the ecosystem, by examining the forest’s rate of carbon sequestration and capability of carbon storage. The literature study concluded that older forests, in total, store larger amounts of carbon, while middle-aged forests have he highest growth rate (net ecosystem production, NEP, and gross primary production, GPP) and that NEP is negative in the first ten years. The study showed some uncertainty concerning carbon uptake in old forests. Several variables, such as the effects of substitution, disturbances and biodiversity were not examined in this study and need to be further considered before making decisions. However, the literature study suggests that it is more beneficial to leave old forests as a carbon sink, since emissions of carbon dioxide urgently need to be reduced. Another purpose of the study was to examine the misconceptions that students, in the later school years, have regarding the carbon cycle. This study found misconceptions concerning photosynthesis and respiration in plants, the role of decomposers, as well as getting concepts mixed up with one another. To solve this problem, assignments could be designed where atoms are traced between different levels, in order to put the processes in context. A large part of the focus regarding these misconceptions has been on photosynthesis and respiration and no articles were found regarding e.g. the fast; and the slow; carbon cycle. Few studies of Swedish students have been made and since the Swedish curriculum focuses on the relationship between different levels, the misconceptions might be different in Sweden; what these misconceptions could be in Swedish schools is yet to be investigated.
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NPR Borečský vrch jako exkurzní cíl výuky botaniky na SŠ / NPR Borečský vrch as a Excursion DestinationBarcalová, Milada January 2013 (has links)
The aim of the present paper is to analyze the curricula for secondary schools in terms of mosses and subsequently prepare a botanical excursion to the NNL Borečský Hill with appropriate didactic materials. Textbooks were compared according to several criteria - the frequency of species of mosses, visual aid, information on the ecology and significance of mosses to ecosystem and human well-being, ideas on field trips and work activities. Topics relating to the planned excursion were selected from the Framework Education Programme. At first, the paper summarizes information about the selected location NNL Borečský Hill which I visited in August 2012 and February 2013. Then an exploration and evaluation of botanical sites follow. There are eight designated sites where the students would perform set tasks. The Chapter: Excursion Proposal contains educational materials created for the excursion - characteristics of selected plant species, characteristic species of bryophytes listed in the field guide, the field guide to bryophytes used on location as well as during laboratory work, route guide for teachers, student worksheets. The materials were tested by students in laboratory work in March 2013 and during the postponed excursion (due to bad weather) in April 2013. The results of the verification are...
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Ecofisiologia e produtividade de Bambusa, Eucalyptus e Salix em sistemas florestais de curta rotação / Ecofisiological and productivity of Bambusa, Eucalyptus and Salix in short rotation woody cropsVergara, Gabriela Carolina Villamagua 04 June 2018 (has links)
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Previous issue date: 2018-06-04 / Outra / Com a necessidade de buscar espécies florestais mais eficientes na utilização dos recursos naturais como luz, água e nutrientes, o que pode possibilitar um incremento da biomassa da parte aérea, o objetivo do presente trabalho foi o de quantificar as taxas de crescimento, eficiência da utilização da luz, água e nutrientes de florestas energéticas sob mesmas condições de solo, altitude e manejo. Foram utilizados plantios adensados de Bambusa vulgaris, híbrido espontâneo de Eucalyptus urophylla – clone AEC-144, híbrido interespecífico de Eucalyptus grandis × Eucalyptus urophylla - clone LW07 e Salix nigra. A determinação da produtividade primária líquida do tronco (PPLT), eficiência do uso da luz (EUL), eficiência do uso da água (EUA) foram obtidas através de acompanhamentos mensais e individuais em 15 plantas por espécie, no período de 12 meses. Foi obtido dados de: diâmetro e altura total das plantas, e posteriormente, taxa fotossintética (A), taxa transpiratória (E) e condutância estomática (gs). Foi realizada ainda a determinação do índice de vegetação e a coleta de amostras para determinação de macro e micronutrientes em laboratório. A espécie B. vulgaris apresentou o maior valor de biomassa por planta e, consequentemente, os maiores incrementos em matéria seca por planta (8,07 kg pl-1 e 1,56 kg pl-1 ano-1, respectivamente), no entanto, observou-se que clone de E. urophylla AEC-144 obteve maior eficiência no uso da luz por área (1,80 g MJ-1) e maior eficiência intrínseca no uso da água (68,09 μmol CO2 mol H2O-1). Em relação à eficiência do uso da água, o clone E. grandis × E. urophylla - LW07 apresentou o maior valor (4,93 μmol CO2 mol H2O-1). Nota-se que houve diferença em relação ao acúmulo de nutrientes entre as espécies estudadas, sendo que os maiores valores obtidos foi observado em B. vulgaris. / In the search for forest species more efficient in the use of resources (light, water and nutrients) to increase aerial biomass, this study aimed to quantify the growth, light, water and nutrients use efficiency of short rotation plantations under the same conditions of soil altitude and management of Bambusa vulgaris, the spontaneous hybrid of Eucalyptus urophylla - clone AEC-144, interspecific hybrid of Eucalyptus grandis × Eucalyptus urophylla - clone LW07 and Salix nigra. To determine truck net primary productivity trunk (TNPP), light use efficiency (LUE) and water use efficiency (WUE), 15 plants per treatment were monitored monthly for 12 months. Plants diameter and total height were collected, as well as photosynthetic rate (A), transpiration rate (E) and stomatal conductance (gs), using infrared gas analyzer (IRGA) (LI-COR 6400). Vegetation index was also obtained using AccuPAR (LP-80) ceptometer and were collected samples for determination of macro and micronutrients in the laboratory. Bambusa vulgaris was the species that obtained the highest biomass per plant ratio and consequently higher net primary productivity (8.07 kg pl-1 and 1.56 kg pl-1 year-1, respectively), however, clone AEC-144 showed higher light use efficiency per area (1.80 g MJ-1) and higher intrinsic water use efficiency (68.09 μmol CO2 mol H2O-1). Clone LW07 obtained the highest value (4.93 μmol CO2 mol H2O-1) of instantaneous water use efficiency, when compared to other species. There was a difference in nutrient accumulation between species, and the highest values were observed in Bambusa vulgaris.
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Festuca amethystina jako reliktní druh jihomoravských pařezin - základní aspekty biologie druhu a variability morfologických znakůFedorová, Barbora January 2014 (has links)
The aim of this thesis was to obtain initial data about the biology and variability of morphological characters of Festuca amethystina. The first part contains a literature outline while the second part is practical. The terrain work was carried out in the forest of Hodonínská Doubrava, in the southeast part of Moravia and involved finding and surveying microlocations of F. amethystina. The collected data focused on the size of micropopulations and demographic and morphometric characteristics of the species, i.e. the diameter and number of clumps, leave length, height and number of stems, panicle size, number of spikelets and number of caryopsis. The outcomes of this work contain tabular and graphical summaries of the measured data, maps and photographs.
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Avaliação da atividade de ectonucleotidases no córtex cerebral e plaquetas de ratos expostos à fumaça de cigarroThomé, Gustavo Roberto 31 March 2009 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Inflammatory and degenerative pathophysiological processes within the central nervous system (CNS) and platelets are important causes of human disease promoted by cigarette smoke. The objective of the present study was to evaluate
activity of the enzymes that hydrolyze nucleotides and nucleosides in synaptosomes of cerebral cortex and platelets from rats exposed to aged and sidestream diluted
smoke of commercial cigarettes. The animals were randomly divided into two groups (ten rats in each group): control (not exposed to cigarette smoke) and smoke (exposed to cigarette smoke). The smoke group was exposed via inhalation through the nose only 15 minutes per day inside a cigarette smoke exposure chamber during 3 weeks. The results demonstrated that E-NTPDase (with ATP and ADP as
substrate) activity was significantly higher in the smoke group (p<0.05), while the 5'- nucleotidase with AMP as substrate demonstrated decreased activity in the smoke group (p<0.05). However, in platelets activities demonstrated that E-NPP and ENTPDase with ATP as substrate and 5´-nucleotidase with AMP as substrate were
significantly higher in the smoke group (p<0.05) as compared to the control group, while E-NTPDase with ADP as substrate demonstrated decreased activity in the
smoke group (p<0.05). A decrease of adenosine, a neuroprotective nucleoside, was observed in brain, which could lead to damage of the brain tissue. However, in
platelets, there was an increase of adenosine, which may reflect adaptative changes. These alterations caused by cigarette smoke on ectonucleotidase activities may
assist in verifying pathophysiological effects in biological systems. / Os processos patofisiológicos inflamatórios e degenerativos no sistema nervoso central (SNC) e plaquetas são importantes causas de doenças humanas promovidas pela fumaça de cigarro. O objetivo do presente estudo foi avaliar a atividade das enzimas que hidrolisam nucleotídeos e nucleosídeos em sinaptossomas de córtex cerebral e plaquetas de ratos expostos à fumaça envelhecida e diluída inalada por
via secundária de cigarros comerciais. Os animais foram aleatoriamente divididos em dois grupos (10 ratos por grupo): controle (não exposto a fumaça de cigarro) e fumo (exposto a fumaça de cigarro). O grupo fumo foi exposto à fumaça de cigarro 15 minutos por dia no interior de uma câmara de exposição durante 3 semanas. Em relação ao sinaptossoma de córtex cerebral os resultados demonstraram que a
atividade da E-NTPDase (ATP e ADP como substrato) aumentou significativamente no grupo exposto à fumaça de cigarro (p<0.05) e a atividade da 5'-nucleotidase
(AMP com substrato) diminuiu neste grupo (p<0.05), comparado ao grupo controle. Nas plaquetas foi demonstrado um aumento na atividade das enzimas E-NPP e ENTPDase
(ATP como substrato) e 5 -nucleotidase (AMP como substrato) no grupo exposto à fumaça de cigarro (p<0.05) quando comparado ao grupo controle. Já a ENTPDase
(ADP como substrato) demonstrou uma diminuição de sua atividade no grupo exposto à fumaça de cigarro (p<0.05). Pode-se sugerir que a provável diminuição da adenosina, uma molécula neuroprotetora, pode levar ao dano no
tecido do encéfalo. Entretanto, em plaquetas, houve um aumento da adenosina, a qual pode refletir mudanças adaptativas. As alterações na atividade das ectonucleotidases em animais submetidos à exposição de fumaça de cigarro podem contribuir na elucidação de seus efeitos patológicos em sistemas biológicos.
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Phase transition and landscape statistics of the number partitioning problemStadler, Peter F., Hordijk, Wim, Fontanari, Jose F. 17 October 2018 (has links)
The phase transition in the number partitioning problem (NPP), i.e., the transition from a region in the space of control parameters in which almost all instances have many solutions to a region in which almost all instances have no solution, is investigated by examining the energy landscape of this classic optimization problem. This is achieved by coding the information about the minimum energy paths connecting pairs of minima into a tree structure, termed a barrier tree, the leaves and internal nodes of which represent, respectively, the minima and the lowest energy saddles connecting those minima. Here we apply several measures of shape (balance and symmetry) as well as of branch lengths (barrier heights) to the barrier trees that result from the landscape of the NPP, aiming at identifying traces of the easy-hard transition. We find that it is not possible to tell the easy regime from the hard one by visual inspection of the trees or by measuring the barrier heights. Only the difficulty measure, given by the maximum value of the ratio between the barrier height and the energy surplus of local minima, succeeded in detecting traces of the phase transition in the tree. In addition, we show that the barrier trees associated with the NPP are very similar to random trees, contrasting dramatically with trees associated with the p spin-glass and random energy models. We also examine critically a recent conjecture on the equivalence between the NPP and a truncated random energy model.
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Contribution l'étude des convertisseurs multiniveaux destinés aux applications moteurs rapides / Contribution to the study of multilevel inverters for high speed motors applicationsGuennegues, Virginie 07 December 2009 (has links)
Cette thèse traite des convertisseurs multiniveaux destinés aux applications moteurs rapides, utilisés notamment dans le domaine de l'Oil \& Gas. L'objectif est l'étude d'une structure qui permette de réduire les pertes par commutation, en comparaison avec la topologie conventionnelle NPC (Neutral Point Clamped) 3 niveaux, actuellement utilisée. De plus, la structure de convertisseur doit permettre de fournir des grandeurs d'entrée au moteur ayant un faible taux de distorsion harmonique, de manière à ne pas créer des échauffements supplémentaires dans le moteur.Après avoir effectué une étude des différentes structures existantes, la structure NPP (Neutral Point Piloted) 3 niveaux est finalement retenue au vu de ses différentes qualités. En effet, grâce à la mise en série de composants semi-conducteurs, les pertes par commutation de ces derniers sont divisées par deux par rapport aux composants homologues de la topologie NPC. Après avoir comparé les topologies NPC et NPP en termes de forme d'onde et de répartition des pertes dans les composants, l'auteur s'intéresse à la validation expérimentale de cette structure. Les performances atteintes par le convertisseur NPP sont intéressantes puisqu'elles permettent de commuter à des fréquences deux fois plus élevées que la topologie NPC pour un courant donné ou de commuter un courant plus important pour une fréquence de commutation donnée.Les schémas de commutation des différents composants du bras NPP sont étudiés afin de comprendre le gain non négligeable obtenu sur cette structure.Malgré le fait que la structure NPP permette de commuter à des fréquences deux fois plus élevées que la structure NPC, on ne peut pas s'affranchir du filtre sinus en sortie de l'onduleur de manière à respecter les contraintes harmoniques au niveau du moteur. Ainsi, une topologie de filtre sinus à inductances couplées a été introduite / This PhD thesis deals with multilevel inverters dedicated to high speed motors applications, used in Oil \& Gas applications. The main objective is to study a topology which enables reducing switching losses, in comparison with the conventional 3-level NPC (Neutral Point Clamped) topology. Moreover, the inverter has to provide motor input signals with a low harmonic distortion level, not to create undesired additional heating in the motor. After a study of the existing topologies, the 3-level NPP (Neutral Point Piloted) topology is chosen regarding all its benefits. Indeed, thanks to series connection of semi-conductor components, switching losses can be divided by two compared to homologous components on the NPC topology. After having compared NPC and NPP topologies in terms of waveforms and losses distribution in components, the author interest is the experimental validation of this topology. The performances reached by the NPP inverter are interesting because it enables to switch two times faster than for a NPC topology for a given current or to switch a higher current for a given switching frequency. The switching schemes of the NPP leg are studied to understand the gain obtained on this topology. In spite of the fact that switching frequency can be doubled on the NPP topology, the sinus filter can not be avoided in order to respect harmonic specification on the motor. A sinus filter with coupled inductances is introduced so that to responds the different sizing criteria
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Molns inverkan på satellitdetektion av vegetationsbränder i Sverige / The Impact of Clouds on VIIRS Active Fire Satellite Detection in SwedenLetalick, Marcus January 2022 (has links)
Results are presented from the 2021 test run of active fire detection using the Visual Infrared Imaging Radiometer Suite (VIIRS) instrument, that is currently onboard the polar satellites Suomi-NPP and NOAA-20. The test is performed by the Swedish Civil Contingencies Agency and the Swedish Meteorological and Hydrological Institute, in cooperation with local fire departments in Sweden. The aim of this report was to study the impact of clouds on the ability of active fire detection, as well as to identify objects that potentially can cause commission errors in the VIIRS 375 m active fire algorithm (false positive notifications). Also, the study aimed to investigate what may cause omission errors in the algorithm, and to show to what extent the detections can be used to represent the true time development of the wildfire front and burned area. Using a cloudmask and a cloudtype classification product from Nowcasting Satellite Application Facilities (NWC SAF), the impact of clouds was anlalyzed by comparing the cloud data with the obtained fire notifications from the satellites. Active fires and newly burned areas were also studied using Sentinel-2 imagery, specifically the False Color Urban and the Short Wave Infrared (SWIR) RGB composites, as well as images from the 842 nm band, making use of the relatively high spatial resolution as well as the spectral signatures of fire and newly burned vegetation. Detection of active fires occurred in both cloud free and completely cloud covered conditions. How-ever, roughly 70% of the detected vegetation fire pixels were obtained in conditions with 20% clouds or less. / I rapporten presenteras resultat från 2021 års test av satellitdetektering av skogs- och vegetationsbränder, ett test som genomförs av MSB och SMHI i samverkan med kommunala räddningstjänster. De två satelliter som ingår i testet (Suomi-NPP och NOAA-20) går i polära omloppsbanor och är utrustade med instrumentet Visible Infrared Imaging Radiometer Suite (VIIRS). Detta projekt syftade till att undersöka hur molnighet påverkar möjligheten till detektion med satellit, vilka objekt som potentiellt kan ge upphov till falska detektioner samt vad som kan orsaka uteblivna satellitdetektioner. Ytterligare ett mål med rapporten var att genom fallstudier av större bränder undersöka i vilken utsträckning satellitdetektionerna kan användas för att representera brandfrontens utveckling med tiden och brandens faktiska utbredning. Vid studierna av molnighet analyserades en molnmask och en molnklassificeringsprodukt från Nowcasting Satellite Application Facilities (NWC SAF). I utvärderingen användes även data från Sentinel-2 för att studera pågående bränder och avbränd yta, som syns tydligt i RGB-kompositerna False Color Urban och Short Wave Infrared (SWIR) och i 842 nm-bandet, tack vare den relativt höga bildupplösningen och den nyligen avbrända ytans spektralsignatur. Brand detekterades i både molnfria och helt molntäckta förhållanden. Drygt 70 % av detektionerna vid vegetationsbrand kom emellertid i förhållanden med 20 % moln eller mindre.
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