Les glaces du milieu interstellaire sont invoquées comme l'une des origines de la formation de molécules organiques complexes dans l'espace. En effet, elles constituent un support catalytique pour des réactions chimiques et pourraient ainsi expliquer la formation de molécules d'intérêt prébiotique. Toutefois, en raison de la faible température des milieux considérés, la vitesse de la réaction est contrainte par le déplacement des différentes réactifs l'un vers l'autre. L'objectif de cette thèse est donc de traiter la réactivité et la diffusion de molécules simples dans les glaces interstellaires. Je présente dans cette thèse les résultats de l'étude de la réaction entre le dioxyde de carbone et l'ammoniac dans les glaces interstellaires. Cette étude a été effectuée au Laboratoire Univers et Particules de Montpellier ; elle combine différentes méthodes de la chimie théorique et confronte les résultats avec ceux issus d'expériences que j'ai réalisées au Laboratoire de Physique des interactions Ioniques et Moléculaires de l'Université d'Aix-Marseille. Dans une première partie, des simulations de dynamique moléculaire classiques sont employées pour simuler un modèle de glace amorphe basse densité. Ce modèle est utilisé pour simuler la trajectoire de petites molécules (NH3, CO, CO2, H2CO) dans cette glace et en déduire des coefficients de diffusion à différentes températures. Ces résultats sont comparés à des résultats expérimentaux de diffusion du dioxyde de carbone ce qui valide la méthode théorique utilisée et permet de suggérer un mécanisme pour ce processus de diffusion. Dans une deuxième partie, la réaction entre le dioxyde de carbone et l'ammoniac est traitée dans le cadre de la théorie de la fonctionnelle densité par une approche « super-molécule ». Dans cette approche, le profil d'énergie et le mécanisme de la réaction dans des complexes moléculaires xNH3:CO2:yH2O sont étudiés. Deux produits de la réaction sont localisés : le carbamate d'ammonium et l'acide carbamique. La barrière d'énergie de la réaction obtenue est similaire à celle obtenue expérimentalement, et le carbamate d'ammonium est confirmé comme produit majoritaire de la réaction. Le profil d'énergie obtenu par cette approche « super-molécule » est ensuite étudié par dynamique moléculaire ab initio contrainte et le profil d'énergie libre est calculé par la méthode d'Intégration Thermodynamique. Cette approche confirme la forme générale du profil d'énergie et met en évidence un fort effet entropique du réseau d'eau. Je dresse finalement des conclusions sur les plans méthodologiques et astrochimiques permettant d'inscrire ma thèse dans des perspectives futures, notamment en incluant les barrières d'énergie de diffusion et de réaction, dans des modèles astrochimiques prenant en compte directement les réactions chimiques dans les glaces interstellaires. / It is postulated nowadays that complex organic molecules in space form on the surface and in the volume of interstellar ices. These ices can catalyse chemical reactions what could explain the formation of prebiotic molecules. However, because of the low temperatures, the diffusion of the reactants one towards another is slow, limiting their reactivity. The objectif of this thesis is to treat the reactivity and the diffusion of simple molecules in interstellar ices. I present in this thesis the results of the study of the chemical reaction between carbon dioxide and ammonia in interstellar ices. This study was conducted in the Laboratoire Univers et Particules de Montpellier : it combines various theoretical chemistry methods and confront the results to experimental ones I participated in at the Laboratoire de Physique des Interactions Ioniques etMoléculaires of the Aix-Marseille university. In a first part, classical molecular dynamic simulations are used to simulate a low-density amorphous ice model and to calculate the diffusion coefficients at various temperatures of a series of small molecules (NH3, CO, CO2, H2CO). These results are compared to the experimental diffusion coeficients of the carbon dioxide validating the theoretical approach used and allowing to porpose a mechanism for the diffusion process. In a second part, the reaction between carbon dioxide and ammonia is studied in the frame of Density-Functional Theory using a « super-molecular » approach. In this approach, the reaction energy profile for the molecular complexes xNH3:CO2:yH2O, is studied. Two reaction products are localised : the ammonium carbamate and the carbamic acid. The reaction energy barrier obtained by these calculations is similar to the one obtained experimentally, and the ammonium carbamate is confirmed as the major reaction product. The obtained energy profile is therfore investigated by constrained ab initio molecular dynamics and the free energy profile is computed with the Thermodynamics Integration method. These calculations confirme the general form of the previous energy profile and enlight the strong entropic effect of the water network. Finally, conclusions are drawn, and perspectives on methodological as well as on astrochemical aspects, as the inclusion of the reaction and diffusion energy barriers I calculated in astrochemical models, are given.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references. Also available on the Internet.

abstract: In this thesis I model the thermal and structural evolution of Kuiper Belt Objects (KBOs) and explore their ability to retain undifferentiated crusts of rock and ice over geologic timescales. Previous calculations by Desch et al. (2009) predicted that initially homogenous KBOs comparable in size to Charon (R ~ 600 km) have surfaces too cold to permit the separation of rock and ice, and should always retain thick (~ 85 km) crusts, despite the partial differentiation of rock and ice inside the body. The retention of a thermally insulating, undifferentiated crust is favorable to the maintenance of subsurface liquid and potentially cryovolcanism on the KBO surface. A potential objection to these models is that the dense crust of rock and ice overlying an ice mantle represents a gravitationally unstable configuration that should overturn by Rayleigh-Taylor (RT) instabilities. I have calculated the growth rate of RT instabilities at the ice-crust interface, including the effect of rock on the viscosity. I have identified a critical ice viscosity for the instability to grow significantly over the age of the solar system. I have calculated the viscosity as a function of temperature for conditions relevant to marginal instability. I find that RT instabilities on a Charon-sized KBO require temperatures T > 143 K. Including this effect in thermal evolution models of KBOs, I find that the undifferentiated crust on KBOs is thinner than previously calculated, only ~ 50 km. While thinner, this crustal thickness is still significant, representing ~ 25% of the KBO mass, and helps to maintain subsurface liquid throughout most of the KBO's history. / Dissertation/Thesis / M.S. Astrophysics 2013

Orientador: Helena Maria Andre Bolini Cardello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T19:15:52Z (GMT). No. of bitstreams: 1 Silva_Karla_M.pdf: 2005223 bytes, checksum: cdd75d59efe54c8d3d07fe38f86b7b39 (MD5) Previous issue date: 2004 / Resumo: O soro de leite bovino é um subproduto da manufatura de queijo ou caseína caracterizado por sua funcionalidade e valor biológico. O soro ácido, obtido da coagulação ácida do leite, apesar do seu valor funcional ainda é considerado um rejeito industrial. Neste contexto, foi proposta a adição de produto do soro ácido de leite (SAP), em cinco diferentes níveis de substituição do leite em pó, na formulação de sorvete. A avaliação do efeito provocado, pela introdução do SAP no sorvete, foi feita por teste sensorial. Considerando ainda os fabricantes de sorvete que, reconhecendo a importância funcional e nutricional dos produtos de soro de leite, gostariam de aumentar os níveis de substituição por estes produtos em suas formulações, efetuou-se aplicação de leite em pó desnatado e diferentes substituintes deste (SAP, soro desmineralizado e concentrado protéico de soro 35%), comparando-se os resultados. A primeira etapa do trabalho identificou uma boa aceitação dos provadores para o produto contendo 30% de SAP, sendo este nível selecionado para continuidade do trabalho. Na segunda etapa as misturas foram caracterizadas (proteína, gordura, minerais, açúcar, sólidos totais, pH, acidez titulável, viscosidade, temperatura de congelamento e frações protéicas) e os produtos aerados e congelados submetidos a avaliações físicas (potencial de aeração, firmeza e resistência ao derretimento), aspectos ultra-estruturais e testes sensoriais. Os resultados demonstraram que a introdução do SAP aumentou a viscosidade da mistura, manteve o potencial de aeração, estabilizou a firmeza e melhorou a estrutura microscópica do sorvete comparativamente com a formulação padrão (sem substituição do leite). Houve boa aceitação dos provadores para as formulações com substituição do leite desnatado por 30% de SAP, 100% de desmineralizado e 100% de concentrado protéico de soro / Abstract: Whey protein is a by product of cheese or casein production, which is characterized by a high functionality and biological value. Acid whey protein is obtained by acid coagulation of milk, has been viewed as dairy wastes so represent a critical environmental pollution. In this context, we proposed the acid whey addition in ice cream formulations, as a dry skim milk total or parcial substitute, ascertaining by sensory evaluation the panelists acceptance for five different substitutions levels. Ice cream manufacturers interesting in increasing the percentual of this product in ice cream formulations showed the importance of the comparative application of dry skim milk and others different replacers (acid whey product, demineralized whey and whey protein concentrate) in ice cream formulations. At the first stage of this work a good panellists acceptance for 30% acid whey product content product was obtained then this level was selected to the followed experiments. In the second level mixtures were characterized (protein, fat, minerals, sugar, total solids, pH, titratable acidity, viscosity, freezing temperature and proteins fractions) and whippened and freezing products were submitted to physical evaluations (whipping potential, firmness and melting resistance), structural electron microscopy aspects and sensory evaluations. Results showed that acid whey addition in ice cream formulations increased the viscosity of mix, maintained the whipping ability, stabilized the firmness and improved the microscopic structure, as the standard product comparison (formulation without milk substitutions). There was good sensory panel acceptance for all milk substituted formulations (30% acid whey product, 100% demineralized whey and 100% whey protein concentrate) / Mestrado / Mestre em Alimentos e Nutrição

<p>  </p> <p>A Cummins 6.7L natural gas engine enabled with VVA was installed in a research test cell at Purdue’s Ray Herrick Laboratories for experimental testing. The stock engine which was connected to an AC dynameter was mounted on a movable test bed outfitted with numerous sensors, a charge air cooler, and an external heat exchanger. In the engine control room, a few different systems were set up to run the dyno, collect data from the engine sensors, and monitor the safety apparatuses in the test cell. </p> <p>After the test cell setup was completed, an initial baseline testing was performed to compare the stock engine operation with the baseline engine data given in the Cummins fuel map. The testing was used to verify the engines stock functionality and troubleshoot some additional issues before setting the boundary conditions. Once the boundary conditions were set, a final stock engine testing was performed at rated to check for repeatability and verify stock engine operation following the engine modifications made to accommodate the VVA. </p> <p>Following the baseline testing, the VVA system was assembled on the standalone rig to verify its operation before mounting it on the engine. In order to run the natural gas valve profiles received from Cummins, the VVA controller gains were retuned and the LVDT sensors were calibrated so that the desired closing, opening and lift behaviors were achieved. After verifying the VVA’s functionality, the hardware was mounted on the engine for the VVA experimental testing. </p> <p>The initial VVA testing was focused on understanding the impacts of intake valve modulation on the gas exchange process. Based on previous simulation work, reductions in pumping work leading to better fuel economy is one expected outcome. Experimental testing data related to the engine performance and operation was used to compare each IVC case to the stock IVC timing. These results were also compared to the previous GT-Power work to identify any apparent trends.</p> <p>Future work includes using VVA to further improve efficiency in the part load region, and reduce knock at higher loads. Additionally, the incorporation of a laser based in-cylinder sensing system will help to optimize the capability of VVA.</p>

The European Commission manages fish stocks by applying a fishing mortality based on the maximum sustainable yield concept. So far most Baltic Sea fishing maximum sustainable yieldmodels have focused on one species at a time. The few existing multi-species models have assumed that a species’ maturity and growth is dependent on the availability of food. Our two-species models make it possible to investigate if there is a conflict between fishing maximum sustainable yield for cod and herring in the Baltic Sea. This two-species model of cod, as a predator and herring as prey, takes into account environmental drivers on cod and herring recruitment. Reproductive volume together with year-growth, (a year specific effect on growth of external variables like food availability) and predation by grey seals was included in the cod model. The herring model was dependent on cod spawning stock biomass and year-growth. The result shows that the reproductive volume is the main factor that affects the maximum sustainable yield for cod. The spawning stock biomass at maximum sustainable yield is more sensitive to reproductive volume than year-growth. When predation from seals is added in mortality and high environmental factors occurs the spawning stock biomass would be 50% compared to the spawning stock biomass at high environmental effects without seal predation. Four simulations of high cod spawning stock biomass were devastating for the herring population that was eradicated with high predation pressure. The herring maximum sustainable yield depends on the amount of cod spawning stack biomass i.e. the effect of high or low reproductive volume. Two analyses were made on a current environmental state for both species. The first analysis had a natural mortality of 0.2 for cod, which gave an fishing mortality of 0.20 and maximum sustainable yield of 410 000 tons. The herring had a fishing mortality of 0.03 and maximum sustainable yield of 11 000 tons. The second simulation included seal predation in cod mortality which decreased the cod maximum sustainable yield by 98% at a fishing mortality of 0.02, which gave a fishing mortality of 0.19 and maximum sustainable yield of 275 000 tons for herring. This gives a 25 times increase of herring maximum sustainable yield compared to the result without predation on cod. The cod population dynamics is vulnerable to environmental changes and to secure a healthy and productive cod population the target fishing mortality should be kept in phase with current reproductive volume. / Europeiska kommissionen förvaltar fiskbestånden genom att tillämpa fiskekvoter baserat på konceptet maximalt hållbart uttag. Hittills har de flesta maximalt hållbara fiske-fångst modeller för Östersjön fokuserat på en art i taget. De få befintliga fler-arts-modeller har antagit att en arts mognad och tillväxt är beroende av tillgången på föda. Vår två-arts-modell gör det möjligt att undersöka om det finns en konflikt mellan maximal hållbar fiske-fångst på torsk och sill i Östersjön. Denna två-arts-modell med torsk som ett rovdjur och sill som byte, tar hänsyn till miljön som drivkraft på deras rekrytering. I torskmodellen ingick reproduktiv volym tillsammans med årlig tillväxt (ett års specifika effekt på tillväxten beroende av externa variabler som tillgången till föda) och predation av gråsäl. Sill-modellen var beroende av årlig tillväxt och lekbeståndets biomassa hos torsk. Resultaten visar att den viktigaste faktorn som påverkar maximalt hållbart uttag för torsk är reproduktiv volym. Lekbeståndets biomassa vid maximalt hållbart uttag är mer känsligt för förändringar i reproduktiv volym än årlig tillväxt. När predation från säl tillsätts och höga gynnsamma miljöfaktorer råder är lekbeståndets biomassa 50 % jämfört med lekbeståndets biomassa vid höga gynnsamma miljöeffekter utan säl predation. Fyra simuleringar gav hög lekbestånds biomassa för torsk vilket var förödande för sillpopulationen som utrotades pga. högt predationstryck. Sillens maximala hållbara uttag beror på mängden lekbestånds biomassa hos torsk, d.v.s. effekten av hög eller låg reproduktiv volym. Två analyser gjordes på nuvarande miljömässiga nivåer för båda arterna. Den första analysen hade en naturlig dödlighet på 0,2 för torsk, vilket gav en fiske-mortalitet på 0,20 och maximalt hållbart uttag på 410 000 ton. Sillen hade en fiske-mortalitet på 0,03 och maximalt hållbart uttag på 11 000 ton. I den andra simuleringen ingår sälpredation på torsk vilket minskade torskens maximala hållbara uttag med 98 % vid en fiske-mortalitet på 0,02, vilket gav en fiske-mortalitet på 0,19 och maximalt hållbart uttag på 275 000 ton för sill. Detta ger en ökning av maximalt hållbart uttag för sill 25 gånger jämfört med resultatet utan predation på torsk. Torskens populationsdynamik är sårbar för miljöförändringar och för att säkra ett sunt och produktivt torskbestånd bör fiskemortaliteten hållas i fas med nuvarande reproduktiva volym.

Empresas de diferentes ramos e portes estão sentindo os efeitos da globalização e para sua manutenção no mercado com vantagens competitivas, precisam buscar condições mais favoráveis que suas concorrentes para desempenhar suas atividades e oferecer produtos com menor preço e melhor qualidade. Além disso, essa competitividade exige níveis de qualidade elevados, bem como comprometimento com a melhoria de seus produtos, serviços, processos e com os colaboradores. Várias são as ferramentas da qualidade utilizadas para o controle na produção de alimentos, porém poucas são aplicadas ou descritas para a produção de gelados comestíveis. Assim, o objetivo desta dissertação é propor a melhoria dos indicadores de desempenho da empresa através das ferramentas da qualidade no processo produtivo de gelados comestíveis. A pesquisa foi realizada em uma unidade regional de fabricação de gelados comestíveis, onde primeiramente foram identificados os possíveis pontos de contaminação no processo produtivo, através de observações in loco e preenchimento de check-list. Em seguida foram coletadas 48 amostras das três caldas bases, branca, morango e chocolate em três pontos do processo produtivo, sendo: resfriamento, pasteurização e saborização, bem como do produto pronto. Essas amostras foram submetidas à avaliação microbiológica para a identificação de possíveis contaminações. A partir desses resultados foram implementadas as ferramentas de qualidade e repetidas as avaliações microbiológicas para a verificação da eficiência das ações empregadas por meio ferramentas de qualidade. A partir da implementação dessas ferramentas, pode ser observada melhoria durante o processo produtivo, eliminando ou diminuindo o risco de falhas durante o processo, bem como do produto final. / Companies in different industries and sizes are feeling the effects of globalization and its maintenance in the market with competitive advantages need to seek more favorable terms than their competitors to perform their activities and offer products with lower price and better quality. Furthermore, this competitiveness requires high levels of quality and commitment to the improvement of its products, services, processes and collaborators. There are several tools used for quality control in food production, but few are implemented or described for the production of ices. The objective of this dissertation is to propose the improvement of the performance indicators of the company through quality tools in the production process of ices. The survey was conducted in a regional manufacturing unit ices, where first the possible points of contamination were identified in the productive process, through on-site observations and completing checklist. Then 48 samples of the three bases tails, white, strawberry and chocolate were collected at three points of the production process, as follows: cooling, pasteurization and saborização as well as the finished product. These samples were subjected to microbiological evaluation to identify possible contamination. From these results have been implemented quality tools and repeated microbiological evaluations to verify the efficiency of the actions employed by quality tools. From the implementation of these tools, improvement can be observed during the production process by eliminating or reducing the risk of failure during the process as well as the final product.

Empresas de diferentes ramos e portes estão sentindo os efeitos da globalização e para sua manutenção no mercado com vantagens competitivas, precisam buscar condições mais favoráveis que suas concorrentes para desempenhar suas atividades e oferecer produtos com menor preço e melhor qualidade. Além disso, essa competitividade exige níveis de qualidade elevados, bem como comprometimento com a melhoria de seus produtos, serviços, processos e com os colaboradores. Várias são as ferramentas da qualidade utilizadas para o controle na produção de alimentos, porém poucas são aplicadas ou descritas para a produção de gelados comestíveis. Assim, o objetivo desta dissertação é propor a melhoria dos indicadores de desempenho da empresa através das ferramentas da qualidade no processo produtivo de gelados comestíveis. A pesquisa foi realizada em uma unidade regional de fabricação de gelados comestíveis, onde primeiramente foram identificados os possíveis pontos de contaminação no processo produtivo, através de observações in loco e preenchimento de check-list. Em seguida foram coletadas 48 amostras das três caldas bases, branca, morango e chocolate em três pontos do processo produtivo, sendo: resfriamento, pasteurização e saborização, bem como do produto pronto. Essas amostras foram submetidas à avaliação microbiológica para a identificação de possíveis contaminações. A partir desses resultados foram implementadas as ferramentas de qualidade e repetidas as avaliações microbiológicas para a verificação da eficiência das ações empregadas por meio ferramentas de qualidade. A partir da implementação dessas ferramentas, pode ser observada melhoria durante o processo produtivo, eliminando ou diminuindo o risco de falhas durante o processo, bem como do produto final. / Companies in different industries and sizes are feeling the effects of globalization and its maintenance in the market with competitive advantages need to seek more favorable terms than their competitors to perform their activities and offer products with lower price and better quality. Furthermore, this competitiveness requires high levels of quality and commitment to the improvement of its products, services, processes and collaborators. There are several tools used for quality control in food production, but few are implemented or described for the production of ices. The objective of this dissertation is to propose the improvement of the performance indicators of the company through quality tools in the production process of ices. The survey was conducted in a regional manufacturing unit ices, where first the possible points of contamination were identified in the productive process, through on-site observations and completing checklist. Then 48 samples of the three bases tails, white, strawberry and chocolate were collected at three points of the production process, as follows: cooling, pasteurization and saborização as well as the finished product. These samples were subjected to microbiological evaluation to identify possible contamination. From these results have been implemented quality tools and repeated microbiological evaluations to verify the efficiency of the actions employed by quality tools. From the implementation of these tools, improvement can be observed during the production process by eliminating or reducing the risk of failure during the process as well as the final product.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2017-04-13T20:27:12Z No. of bitstreams: 1 Tese - Janaina Cristina de Jesus - 2016.pdf: 3122516 bytes, checksum: 167623af01b412fcc58bcdcb6c1cc311 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-17T11:12:51Z (GMT) No. of bitstreams: 1 Tese - Janaina Cristina de Jesus - 2016.pdf: 3122516 bytes, checksum: 167623af01b412fcc58bcdcb6c1cc311 (MD5) / Made available in DSpace on 2017-04-17T11:12:51Z (GMT). No. of bitstreams: 1 Tese - Janaina Cristina de Jesus - 2016.pdf: 3122516 bytes, checksum: 167623af01b412fcc58bcdcb6c1cc311 (MD5) Previous issue date: 2016-11-30 / This study is linked to the research line State, Policies and History of Education and has as its object the extension in Catholic Community Universities. Its general objective was to analyze the multiple determinations that have influenced the conceptions of extension in Catholic Universities that, since the approval of Federal Law 12.881, on November 12th in 2013, are now part of a specific group in the scope of higher education: Community Institutions of Higher Education - ICES. The following questions guided the investigation: what determines the conceptions of extension of the Catholic Community Universities? In what way has university extension contributed, over time, for the ICES to maintain their differentiated identity before the State? The studies revealed that: i) there is not only a conception of extension in force in Brazilian universities. Such conceptions are forged in the conceptions of a disputed university in society and are, in one way or another, also referred to the forms of understanding that one has of the relation of exteriority between university and society; ii) the ICES have a complex identity, marked by ambiguities insofar as they converge, in addition to the elements that make up their logos and ethos as a social institution and the particularities of the university in Brazil, the fact that they are nonprofit, mostly philanthropic, therefore in interface with the National Policy of Social Assistance. In addition, their recognition by the State as community IES because of their differentiated work, including through extension, have consolidated them as non-state public institutions - a field that is interposed between public IES and private IES in the strict sense; iii) in the case of Catholic ICES, the orientations emanating from the Catholic Church are added to this identity. From the studies carried out, it is understood that the conceptions of the extension of these Universities determine the tensions between elements of Science, Faith, State and, gradually, the Market, and these elements also conform the identity of these institutions. This calls into question the paradoxes, dilemmas and contradictions that historically demarcate it, and also make it a field of dispute for university conceptions and, at the most, society. As a methodological course, documentary analysis was used in a broad sense, mainly through bibliographical research, analysis of dissertations and theses, and the elaboration of an inventory based on information from the worldwide computer network to characterize ICES and, especially, Of Community Catholic Universities in Brazil and in the World. With the purpose of apprehending conceptions of extension in a Catholic community university, aspects of the extension of the Pontifical Catholic University of Goiás were taken by reference for analysis. / Este estudo vincula-se à linha de pesquisa Estado, Políticas e História da Educação e tem como objeto a extensão em Universidades Comunitárias Católicas. Seu objetivo geral foi analisar as múltiplas determinações que têm incidido nas concepções de extensão em Universidades Católicas que, a partir da aprovação da Lei federal no 12.881, de 12 de novembro de 2013, passam a compor um grupo específico no âmbito da educação superior: as Instituições Comunitárias de Educação Superior – ICES. As seguintes questões orientaram a investigação: o que determina as concepções de extensão das Universidades Comunitárias Católicas? De que modo a extensão universitária tem contribuído, ao longo do tempo, para que as ICES mantenham sua identidade diferenciada perante o Estado? Os estudos revelaram que: i) não há apenas uma concepção de extensão vigente nas universidades brasileiras. Tais concepções são forjadas nas concepções de universidade em disputa na sociedade e estão, de um modo ou outro, também referidas às formas de compreensão que se tem da relação de exterioridade entre universidade e sociedade; ii) as ICES possuem uma identidade complexa, marcada por ambiguidades na medida em que convergem, além dos elementos que compõem seu logos e etos como instituição social e as particularidades da universidade no Brasil, o fato de serem IES sem fins lucrativos, majoritariamente filantrópicas, portanto em interface com a Política Nacional de Assistência Social. Além disso, seu reconhecimento pelo Estado como IES comunitárias em razão do trabalho diferenciado que realizam, inclusive por meio da extensão, consolidaram-nas como instituições públicas não-estatais - campo que se interpõe entre as IES públicas e as IES privadas em sentido estrito; iii) no caso das ICES católicas acrescentam-se a essa identidade as orientações emanadas da Igreja Católica. Dos estudos realizados compreende-se que determinam as concepções de extensão dessas Universidades as tensões entre elementos da Ciência, da Fé do Estado e, gradativamente, do Mercado, sendo que esses elementos também conformam a identidade dessas instituições. Isso põe em questão os paradoxos, dilemas e contradições que a demarcam historicamente e fazem da extensão também um campo de disputa de concepções de universidade e, no limite, de sociedade. Como percurso metodológico utilizou-se a análise documental, em sentido lato, fundamentalmente por meio de pesquisa bibliográfica, análise de dissertações e teses e da elaboração de um inventário a partir de informações constantes da rede mundial de computadores para caracterização das ICES e, especialmente, das Universidades Comunitárias Católicas no Brasil e no Mundo. Com o fito de apreender concepções de extensão em uma universidade comunitária católica, tomou-se por referência para análise aspectos da extensão da Pontifícia Universidade Católica de Goiás.