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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.
41

Quality and Thermophysical Properties of Pressure Treated Foods

Nguyen, Loc Thai January 2009 (has links)
No description available.
42

Factors Influencing the Post-Earthquake Shear Strength

Ajmera, Beena Danny 28 August 2015 (has links)
Although clays are generally considered stable materials under seismic conditions, recent failures initiated in clay layers after earthquakes have emphasized the need to study the cyclic and post-cyclic behavior of these materials. Moreover, if strength loss as a result of cyclic loading were to occur in the material comprising the dam and/or dam foundation, the consequences of failure could be substantial. The objective of this study is to evaluate the effect of plasticity characteristics, mineralogical composition, and accumulated energy on the cyclic behavior, post-cyclic shear strength and the degradation in shear strength due to cyclic loading in normally consolidated clays. Seventeen soil samples prepared in the laboratory from kaolinite, montmorillonite, and quartz were tested using static and cyclic simple shear apparatuses. In addition, the results of cyclic simple shear tests on twelve natural samples were provided by Fugro Consultants, Inc. in Houston, TX. Using the results, cyclic strength curves were developed to represent 2.5%, 5% and 10% double amplitude shear strains. These curves were used to examine the influences of mineralogical composition, plasticity characteristics and shear strain on the cyclic resistance of soil samples. A power function was used to represent the cyclic strength curves. The samples were found to become increasingly resistant to cyclic loading as the plasticity index increased. Moreover, the soils with montmorillonite as the clay mineral were noted to have consistently higher cyclic resistances than the soils with kaolinite as the clay mineral. By examining the power functions, it was found that the cyclic strength curve approaches linearity as the plasticity index increases in soils having kaolinite as the clay mineral. However, the opposite trend is observed in soils having montmorillonite as the clay mineral. The study shows that the post-cyclic shear strength increases with increasing plasticity index. Moreover, the post-cyclic shear strengths of soils with montmorillonite as the clay mineral were significantly higher than the post-cyclic shear strengths of soils with kaolinite as the clay mineral. The degradation in shear strength due to cyclic loading appeared unaffected by mineralogy, but a greater reduction in strength was noted with decreasing plasticity index. The post-cyclic shear strength was also found to reduce as the number of cycles required to cause 10% double amplitude shear strain increased. The energy approach considering the accumulated energy per unit volume in the soil mass as a result of cyclic loading was also utilized in this study. The results from the energy approach were independent of the cyclic wave form, but were still dependent on the amplitude of the cyclic load used during the testing. An increase in the amplitude of the cyclic loading function results in a decrease in the accumulated energy per unit volume. Furthermore, an increase in the liquid limit and/or plasticity index of the soils containing kaolinite as the clay mineral shows an increase in the accumulated energy, whereas an increase in plasticity of the soils containing montmorillonite as the clay mineral results in a decrease in the amount of accumulated energy. In both types of materials, the amount of accumulated energy per unit volume is found to increase with increasing double amplitude shear strain. Relationship between the ratio of post-cyclic undrained shear strength to the baseline undrained shear strength and the accumulated energy is also determined. / Ph. D.
43

La transmission d’entreprise : recherches sur les spécificités de l’entreprise de bâtiment / Business transfer : a research on the specificities of the building trade

Ollier, Hubert 03 June 2014 (has links)
Le contexte démographique, social et économique fait apparaitre un taux de disparition important des entreprises de bâtiment lors de leur transmission. Transmission naturelle, liée à l'âge du dirigeant, ou provoquée lorsqu'il s'agit d'un souhait de ce dernier, le constat est le même : la survivance de l'entreprise au départ du cédant est très limitée. Tenant au secteur d'activité, les justifications des difficultés attachées aux transmissions d'entreprise classiquement avancées ne sont pas pleinement satisfaisantes. Abordé sous l'angle des spécificités de l'entreprise de bâtiment, notre étude entend donc souligner qu'une préparation, une anticipation à la transmission est nécessaire avant de réaliser l'opération. La mise en avant de solutions quant au maintien des connaissances techniques et savoir-faire de l'entreprise ainsi que l'amélioration de son environnement juridique sont caractéristiques du secteur. Ils apparaissent comme des atouts pour attirer, séduire et fidéliser un cessionnaire. Ce n'est qu'après cette étape, qu'il sera fait appel à des techniques, quelques fois inédites, pour favoriser la reprise de l'entreprise. Si la holding de rachat a connu, ces dernières années, un succès sans précédent, l'accès au financement, parfois difficile dans le contexte de crise économique qui touche le secteur, doit également être abordé. Les montages de reprise se complexifient transformant les praticiens en véritables ingénieurs de la stratégie patrimoniale dans laquelle la fiscalité tient une place de choix. / The demographic, social and economic context underlines the high rate of disappearance of the building companies when transferring. Either the natural transfer linked to the owner age or the wish to retire from business expressed by the company manager, the result looks the same: the survival of the company is very limited when leaving. Linked to the sector of activities, the reasons of the difficulties connected to the transfer of companies usually suggested are not fully satisfactory.Viewed in terms of the specificities of the building trade, our study therefore aims to emphasize the need for some preparation, some anticipation of the transfer before carrying out the project. Putting forward solutions to preserve technical knowledge, expertise of the company and legally environmental improvement as well are typical of the sector. They seem to be real assets to attract, appeal and create the transferee loyalty. It is only after this stage that technical means, sometimes innovating in some ways will be applied to improve the business revival. However unprecedented successful the holding company of repurchase got during the last years, access to financing , sometimes difficult in the context of economic crisis which affects the sector must be broached as well. The financial package of acquisition is getting more and more complex, transforming experts into true engineers of the patrimonial strategy in which taxation holds a place of choice.
44

運輸與存貨問題的可行性分析與研究 / Analysis on Transportation and Inventory Problems

林志漢, Lin, Chih - Han Unknown Date (has links)
在本篇論文裡, 我們提出一個"油輪排程規畫"的方法。處理在計畫期間中, 有關原油供應商的供給, 油輪的運輸與需求地儲油庫存貨管理的問題。藉由一些性質的探討來分析運輸排程與存貨管理。由供應油商契約量中供應量的情形, 提出最大累積可提運量表, 並藉由該表來輔助我們做排程; 由分油的概念與訂貨週期的制定, 分析運輸工具的排程狀況與儲油庫油量存貨的關係; 由運輸與儲油庫油料之間的互動關係, 提出管理的方案; 最後再藉由理想存貨量的關念來確立租用臨時運輸工具的可行性。並藉由所提出的性質來處理租用運輸工具的排程。在各個階段的處理過程中, 包括分析限制條件是否滿足的情形等, 總共提出了四個演算法, 找出滿足整個問題限制條件的可行排程。最後, 引用實務上的例子, 來說明油輪排程規畫的方法。 / In this paper, we consider an inventory problem of which the lead time depends on vehicles chosen from a restricted set. The inventory itself hasother constraints that must satisfy the demand and capacity limitation. Inspecific, a problem that considers scheduling oil tankers for transportingcrude oils from supplies to a refinery is represented. With the help of some properties discovered while analyzing the problem of oil tanker scheduling with inventory management, such as largest accumulated supplies from oil suppliers, demand intervals and reorder intervals, and an ideal inventory level, we develope an oil tanker scheduling model to determine each vehicle's schedule and satisfy all constraints. The model consists of four heuristic algorithms which are described step by step asthe solution procedure. A realworld example from an oil company is used to illustrate the four algorithms and suggest a feasible schedule for transporting crude oils. In short, we not only give 1 overall viewpoint of inventory and transportation problems but also provide a heuristic procedurefor solving it.
45

Avaliação de métodos de restauração florestal de Mata Atlântica de Tabuleiros / Evaluation of methods forest restoration of Tableland Atlantic Forest

Klippel, Valéria Hollunder 25 July 2011 (has links)
Made available in DSpace on 2016-12-23T13:51:52Z (GMT). No. of bitstreams: 1 Valeria Hollunder Klippel.pdf: 1679011 bytes, checksum: 81fc92fdc0af96774ee580cab6eba66b (MD5) Previous issue date: 2011-07-25 / This study aimed to evaluate different forest restoration methods of a Tableland Forest, by manipulating the floristic composition and silvicultural practices. With this foundation, it was installed in August of 2007, at the Reserva Natural Vale (RNV) in Linhares - ES, an experiment in randomized blocks with 4 treatments and 3 replications (a total of 12 plots): T1 (Control): Only leafcutter ants control; T2: Selective manual mowing, selective chemical weeding, control of ants and species tolerant to the herbicide; T3: Same as treatment 2, but with the planting of Atlantic Forest pioneer species in the spacing of 5 x 5 m, interspersed, in the same spacing, the seeding of Sesbania grandiflora in pits (10 seeds per pit); T4: Same as treatment 2, but with the planting of 54 Atlantic Forest species in the spacing close to 3 x 3 m. From the moment of installation (2007) until the third year of the study (2010) annual inventories were performed in all plots, to study the arboreal vegetation flora and growth. Moreover, at the third year after the experiment implementation, soil samples were also collected at four depths (0-5, 5-10, 10-20 and 20-40 cm) for later chemical analysis; accumulated litter, for studying biomass and nutrient content and level, and leaf area index (LAI). Regarding the soil chemical attributes, only statistic differences were found for the studied treatments in depths of 0-5 cm, where the highest values of Ca, sum of bases and CEC were observed for the treatment 4 and greater Na Saturation Index value to the treatment 1, and 10-20 cm, where the treatment 4 showed higher Ca value. There were no statistical differences in the accumulated litter biomass. The lower C/N was obtained by the treatment 3. This treatment also had the highest leaf area index. The elimination of weed competition acted positively on trees growth. The entrance of individuals and basal area was higher for treatments 3 and 4 / Esse estudo teve como objetivo avaliar diferentes métodos de restauração florestal de uma Floresta de Tabuleiro, pela manipulação da composição florística e práticas silviculturais. Com esta fundamentação foi instalado em agosto do ano de 2007, na Reserva Natural Vale (RNV) em Linhares ES, um experimento em blocos casualizados, com 4 tratamentos e 3 repetições (totalizando 12 parcelas): T1 (Controle): Somente o controle de formigas cortadeiras; T2: Roçada manual seletiva, capina química seletiva, controle de formigas e as espécies tolerantes ao herbicida; T3: Idêntico ao tratamento 2, mas com o plantio de espécies pioneiras da Mata Atlântica no espaçamento de 5 x 5 m, intercalado, no mesmo espaçamento, o semeio de Sesbania grandiflora em covas (10 sementes por cova); T4: Idêntico ao tratamento 2, mas com o plantio de 54 espécies da Mata Atlântica no espaçamento próximo de 3 x 3 m. Desde o momento de instalação (2007) até o terceiro ano de estudo (2010) foram realizados inventários anuais em todas a as parcelas, para estudo da florística e crescimento da vegetação arbórea. Além disso, no terceiro ano após a implantação do experimento, também foram coletadas amostras de solo em quatro profundidades (0 5; 5 10; 10 20 e 20 40 cm) para posterior análise química; serapilheira acumulada, para estudo da biomassa e do teor e conteúdo de nutrientes; e índice de área foliar (IAF). Em relação aos atributos químicos do solo, somente foram encontradas diferenças estatísticas para os tratamentos estudados nas profundidades de 0-5 cm, onde os maiores valores de Ca, soma de bases e CTC foram observados para o tratamento 4 e maior valor do ISNa para o tratamento 1, e de 10-20 cm, onde o tratamento 4 apresentou maior valor de Ca. Não foram observadas diferenças estatísticas para a biomassa da serapilheira acumulada. A menor C/N foi obtida pelo tratamento 3. Esse tratamento também apresentou o maior índice de área foliar. A eliminação da matocompetição atuou positivamente no crescimento da vegetação arbórea. O ingresso de número de indivíduos e de área basal foi superior para os tratamentos 3 e 4.
46

Étude du phénomène d'électrisation par écoulement : impact d'un champ électrique externe sur la double couche électrique / Study of the flow electrification phenomenon : impact of an external electric field on the electrical double layer

Leblanc, Paul 01 December 2015 (has links)
A l'interface solide-liquide, des réactions physicochimiques conduisent à polariser l'interface et à former la double couche électrique (DCE). La circulation du liquide transporte une partie des charges électriques de la DCE et conduit au phénomène d'électrisation par écoulement. Dans les transformateurs de puissance, constitués, entre autres, d'huile minérale et de carton d'isolement, le phénomène d'électrisation est suspecté d'être à l'origine de certaines défaillances et accidents. Dans cette problématique de risque, de nombreuses études ont été menées et ont permis de mettre en évidence l'influence de paramètres significatifs : nature des matériaux, humidité des matériaux, géométrie et vitesse de l'écoulement, température. Peu d'études se sont concentrées sur l'influence du champ électrique, en particulier les champs continus (DC). Même si le champ électrique généré dans les équipements de puissance est principalement alternatif (AC), il n'en est pas moins vrai que des champs électriques continus (DC) résiduels peuvent être présents, en particulier dans les dispositifs H.V.D.C (High Voltage Direct Current). L'objet du travail s'inscrit dans ce contexte et a pour but, dans une approche à la fois expérimentale et numérique, d'apporter des éléments de réponse sur le développement et le transport des charges de la double couche électrique sous contrainte de champ électrique externe. / At the solid-liquid interface, physicochemical reactions lead to the polarization of the interface and to the formation of an electrical double layer (EDL). The process of flow electrification is due to the convection of part of the electrical charges located in the EDL. In power transformers within which mineral oil and pressboard are commonly used for cooling and electrical insulation, a flow electrification phenomenon is suspected to be responsible of failures. In this hazard assessment problematic, many studies have been made and allowed identifying the influence of significant parameters: nature of materials, moisture level of materials, flow geometry and velocity, temperature. Few studies have focused on the influence of the electric filed, particularly the continuous electric fields (DC). Even though the electric field generated within power transformers is mainly alternating (AC), it is nonetheless true that residual DC electric fields may be detected (e.g. High Voltage Direct Current appartus). This present work fits in this context and aims at providing, both through an experimental and numerical approach, some answers on the development and the transport of charges from the electrical double layer under external electric field stresses.
47

En eventstudie om abnormal avkastning på spelsläpp hos svenska spelutvecklarbolag

Axman Lundbom, Fredric, Nguyen, Edward January 2021 (has links)
This essay examines the impact of game releases on the Swedish stock market. As previous research has examined product launches and news releases, this thesis intends to investigate game releases by game developer companies such as developers of computer, console or mobile games. Previous research has been based on a business perspective and business valuation, the authors of this thesis intend to examine the individual investor's perspective. The theoretical framework consists of information asymmetry, the signaling model, the effective market hypothesis, random walk hypothesis and market reaction to new products. The study has chosen a deductive quantitative research approach with the event study method. The sample consists of 14 game developer companies in computer, console and mobile games during theperiod 2017–2021 that are listed on the Swedish market, which were observed during a period of 180 days before the event day and 40 days after. The results showed that there is a statistically significant relationship before, after and during the event day for game releases.The period during and after the event day can also be generalized where 9/14 respective 10/14 game developer companies showed statistically significant within the accumulated abnormal return. / Denna uppsats undersöker påverkan av spelsläpp på den svenska aktiemarknaden. Då tidigare forskning har undersökt produktlanseringar och nyhetssläpp ämnar denna uppsats att undersöka spelsläpp av spelutvecklarebolag som utvecklar PC-, konsol eller mobilspel. Tidigare forskning har utgått från ett företagsperspektiv och företagsvärdering, författarna för denna uppsats ämnar undersöka den individuella investerarens perspektiv. Det teoretiska ramverket består av informationsasymmetri, signaleringsmodellen, den effektiva marknadshypotesen, random walk hypothesis och marknadsreaktion till nya produkter. Studien har en deduktiv kvantitativa forskningsansats med eventstudie metoden. Urvalet består av 14 spelutvecklarebolag inom dator-, konsol- och mobilspel under tidsperioden 2017–2021 som är börsnoterade på den svenska marknaden. Dessa bolag observerades under en tidsperiod 180 dagar innan eventdagen och 40 dagar efter. Resultatet visade på att det finns ett statistiskt signifikant samband innan, efter och under eventdagen för spelsläpp. Perioden under och efter eventdagen kan även generaliseras där 9/14 respektive 10/14 spelutvecklarbolag visade på statistisk signifikant inom den ackumulerade abnormala avkastning.
48

新財務會計準則第十號公報對企業之影響

廖翊帆 Unknown Date (has links)
隨著國際化的發展,企業為降低財務報表重編的相關成本,採用全球統一的財務會計準則已成趨勢。近年來,我國之財務會計準則委員會陸續修訂了若干公報,其中之一為第十號公報。該公報修訂至生效時期,正值全球金融風暴。因此,政府對實施該公報的時機決策反覆,而企業界、會計界及媒體皆對該公報相當關注。 本研究旨在探討新十號公報對整體市場、各產業及不同特性公司之影響。本研究採用事件研究法,以似乎不相關迴歸模式,分析我國公司在該公報修訂期間及政府實施決策期間之股票累積平均異常報酬率。 研究結果指出,在新十號公報修訂期間,市場對該公報的反應較為負面;在政府政策反覆期間,市場反應則有正有負。各產業部份,電子業於該公報修訂初期受影響較大,推論原因為電子業固定成本高、毛利較低之緣故;而在該公報政府實施決策階段則受影響較小,推論原因為大部分電子業公司均做好因應措施。公司特性部分,大公司對該公報愈持正面態度;老公司則較排斥該公報;前三年度虧損的公司,受該公報影響較小;而成長機會較多之公司,在該公報制定初期受影響較大,但於政府實施決策階段反而受影響較小。 / To pursue globalization, it has been a trend for firms to gradually adopt the International Accounting Standards; that would help reduce the costs related to cross-border restatement of financial reports. To converge with the International Accounting Standards, the Financial Accounting Standards of Taiwan has been revised in recent years. One of the revised standards is the new SFAS No. 10. That revision took place amid the financial crisis. Before the new standard became effective, the government in Taiwan swung on the timing issue of formal adoption. As a result, firms, practitioners, and the media all paid close attention to the new SFAS No. 10. This study aims to examine the revision and adoption decision effects of the new SFAS No. 10 on the stock market, industries, and firms. Firm characteristics that could be factors of the reaction were also examined. This research is an event study using seemingly unrelated regression to analyze the accumulated average abnormal returns of stocks of listed companies in Taiwan. The empirical results are as follows. First, the whole market mostly reacted negatively in the standard revision period and in either way during the standard adoption decision period. Next, in the standard revision period, the electronic industry also reacted negatively, as it would be more affected because of its higher fixed cost and lower gross profit. Yet, in the adoption decision period, the electronic industry was less affected likely because most electronics firms were ready for adoption. Thirdly, as to firm characteristics, bigger firms were willing to adopt the new standard, but older firms were not so. In addition, firms that had losses in the previous three years were less affected by the new standard. Finally, firms that had greater growth opportunities were more affected in the early period of standard revision but became less affected in the adoption decision period.
49

Efeitos da atividade física em marcadores biológicos da carcinogênese química do cólon de ratos Wistar / Physical activity effects on chemical colon carcinogenesis biomarkers in rats.

Demarzo, Marcelo Marcos Piva 04 May 2005 (has links)
Estudos epidemiológicos vêm demonstrando que quantidades apropriadas de atividade física regular estão associadas a significativa redução do risco para o desenvolvimento de câncer de cólon em até 40% entre os indivíduos mais fisicamente ativos. Por outro lado, tem sido observado que o exercício físico exaustivo aumenta a produção sistêmica de radicais livres, com concomitante aumento dos danos oxidativos ao DNA, além de deprimir a função imune global, eventos relacionados ao aumento do risco para o desenvolvimento de câncer. Relativamente, poucos estudos experimentais exploram essas relações, principalmente no que concerne ao exercício exaustivo e o câncer. A taxa de proliferação celular epitelial, os focos de criptas aberrantes (FCAs) e as criptas com acúmulo de beta-catenina (CABC) têm sido marcadores biológicos (biomarcadores) usados para a identificação precoce de fatores que poderiam influenciar a carcinogênese colônica em ratos. Através da aplicação do carcinógeno químico 1,2dimetilhidrazina (DMH), logo após os protocolos de exercício, foram estudados quatro grupos principais de ratos previamente sedentários (grupo-controle, e três grupos submetidos, respectivamente, ao treinamento crônico de natação, à natação até a exaustão, e à natação até a exaustão após treinamento crônico), sendo sacrificados quinze dias após a injeção da DMH. Após análise histológica e imunohistoquímica, os biomarcadores estudados mostraram resultados coerentes nas diferentes situações experimentais aferidas. Foi observada uma diminuição estatisticamente significante da resposta hiperproliferativa, do número de FCAs e de CABC no grupo que realizou o treinamento crônico, enquanto o grupo submetido ao exercício exaustivo apresentou aumento estatisticamente significante dos parâmetros citados, quando comparados ao grupo-controle. No grupo submetido à associação dos dois protocolos de exercício, quando comparado ao grupo-controle, não houve alterações significantes nos biomarcadores de transformação neoplásica estudados. Nesse estudo experimental, o treinamento físico crônico teve efeito protetor contra o desenvolvimento dos biomarcadores precoces de transformação neoplásica do cólon, enquanto o exercício físico exaustivo aumentou a prevalência destes em ratos sedentários. O treinamento físico crônico, quando associado ao exercício físico exaustivo, não alterou a prevalência dos biomarcadores estudados. Desse achado, acrescido do que se pode encontrar na literatura científica atual, levanta-se a hipótese de que, de maneira similar à relação entre exercício físico e infecções, também o exercício poderia ou proteger contra o desenvolvimento, ou aumentar o risco para o câncer, dependendo do tipo, intensidade e duração da atividade desenvolvida. / Ephitelial cell proliferation, aberrant crypt foci (ACF) and â-catenin-accumulated crypts (BCAC) have been used for early detection of factors that influence colorectal carcinogenesis in rats. It has been observed that moderate and regular physical activity may prevent colon cancer up to 40% in humans. However, exhaustive exercise increases free radical DNA oxidative damage and depresses immune function, events also related to the increased risk for cancer development. Fifteen days after either a single exhaustive swimming bout or a swimming physical training for 8 weeks, or both, in untrained rats treated with a colon carcinogen, we observed a statistically significant decreased number of those biomarkers in rats under training protocol, and a statistically significant increased number of them in rats under exhaustive protocol, when compared to the non-exercised group. For the rats under exhaustive protocol after being trained, data was not evident. Thus, we concluded that training protected against the biomakers development and exhaustive exercise improved colorectal carcinogenesis biomarkers development in sedentary rats. From our finding and literature data, we hypothesize that, similarly to the suggested relationship between exercise and infections, exercise could be protective against cancer or it could increase the risk for this disease depending on its type, dose and duration.
50

Efeitos da atividade física em marcadores biológicos da carcinogênese química do cólon de ratos Wistar / Physical activity effects on chemical colon carcinogenesis biomarkers in rats.

Marcelo Marcos Piva Demarzo 04 May 2005 (has links)
Estudos epidemiológicos vêm demonstrando que quantidades apropriadas de atividade física regular estão associadas a significativa redução do risco para o desenvolvimento de câncer de cólon em até 40% entre os indivíduos mais fisicamente ativos. Por outro lado, tem sido observado que o exercício físico exaustivo aumenta a produção sistêmica de radicais livres, com concomitante aumento dos danos oxidativos ao DNA, além de deprimir a função imune global, eventos relacionados ao aumento do risco para o desenvolvimento de câncer. Relativamente, poucos estudos experimentais exploram essas relações, principalmente no que concerne ao exercício exaustivo e o câncer. A taxa de proliferação celular epitelial, os focos de criptas aberrantes (FCAs) e as criptas com acúmulo de beta-catenina (CABC) têm sido marcadores biológicos (biomarcadores) usados para a identificação precoce de fatores que poderiam influenciar a carcinogênese colônica em ratos. Através da aplicação do carcinógeno químico 1,2dimetilhidrazina (DMH), logo após os protocolos de exercício, foram estudados quatro grupos principais de ratos previamente sedentários (grupo-controle, e três grupos submetidos, respectivamente, ao treinamento crônico de natação, à natação até a exaustão, e à natação até a exaustão após treinamento crônico), sendo sacrificados quinze dias após a injeção da DMH. Após análise histológica e imunohistoquímica, os biomarcadores estudados mostraram resultados coerentes nas diferentes situações experimentais aferidas. Foi observada uma diminuição estatisticamente significante da resposta hiperproliferativa, do número de FCAs e de CABC no grupo que realizou o treinamento crônico, enquanto o grupo submetido ao exercício exaustivo apresentou aumento estatisticamente significante dos parâmetros citados, quando comparados ao grupo-controle. No grupo submetido à associação dos dois protocolos de exercício, quando comparado ao grupo-controle, não houve alterações significantes nos biomarcadores de transformação neoplásica estudados. Nesse estudo experimental, o treinamento físico crônico teve efeito protetor contra o desenvolvimento dos biomarcadores precoces de transformação neoplásica do cólon, enquanto o exercício físico exaustivo aumentou a prevalência destes em ratos sedentários. O treinamento físico crônico, quando associado ao exercício físico exaustivo, não alterou a prevalência dos biomarcadores estudados. Desse achado, acrescido do que se pode encontrar na literatura científica atual, levanta-se a hipótese de que, de maneira similar à relação entre exercício físico e infecções, também o exercício poderia ou proteger contra o desenvolvimento, ou aumentar o risco para o câncer, dependendo do tipo, intensidade e duração da atividade desenvolvida. / Ephitelial cell proliferation, aberrant crypt foci (ACF) and â-catenin-accumulated crypts (BCAC) have been used for early detection of factors that influence colorectal carcinogenesis in rats. It has been observed that moderate and regular physical activity may prevent colon cancer up to 40% in humans. However, exhaustive exercise increases free radical DNA oxidative damage and depresses immune function, events also related to the increased risk for cancer development. Fifteen days after either a single exhaustive swimming bout or a swimming physical training for 8 weeks, or both, in untrained rats treated with a colon carcinogen, we observed a statistically significant decreased number of those biomarkers in rats under training protocol, and a statistically significant increased number of them in rats under exhaustive protocol, when compared to the non-exercised group. For the rats under exhaustive protocol after being trained, data was not evident. Thus, we concluded that training protected against the biomakers development and exhaustive exercise improved colorectal carcinogenesis biomarkers development in sedentary rats. From our finding and literature data, we hypothesize that, similarly to the suggested relationship between exercise and infections, exercise could be protective against cancer or it could increase the risk for this disease depending on its type, dose and duration.

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