Histórias de vida de mulheres idosas :um estudo sobre o bem-estar subjetivo na velhice

The elderly population growth in Brazil and in the world is an incontestable reality, arising from a significant declining rate in mortality and fertility, resulting from the remarkable improvements in the quality of life of the people. Associated with the introduction of new technologies in the medical area, these issues have been highly contributing for the increase of the population longevity. The numbers of the elderly in Brazil and in the world show female population predominance within the aging segment, a phenomenon known as the feminisation of the old-age . Aging, therefore, is nowadays one of the primary issues and that has been mobilizing the Brazilian s society, since the development raised from this new reality brought with it enormous challenges and complex social implications which are already felt in the daily lives of the societies. My work experience among some age groups has shown that aging is a much differentiated process which has instigated my interest in understanding why aging has to face an overwhelming and painful experience for some people and enriched and full of signification for others. Overviewing, this research aimed to understand the aging development through the analysis of the processes of signification and production of meaning that permeate the aging and the subjective well-being of three aged women participants of the Project Health and Citizenship on Third Age /CEFET-RN, that evidenced attitudes and behaviors concerning the integration and the activity toward the elderly population. The methodological strategy used was History of Life, starting from collecting data based on deep interviews. The analysis of data evidenced that the elderly well-being is a unique and distinct meaningful experience for each person, concerning each story of their lives within differentiated social, cultural, economic context, from this perspective one can demystify the concept of that aging occurs in a homogeneous way for everyone, everywhere and with the same rhythm. The narratives presented in this research showed the human development as being a dialectic, discursive and interactionist process which extends throughout the adult life and continues to the aging life. The guarantee that development and aging are a parallel phenomenon always in interdependence on the preceding phases of live, are corroborated within the studies. This present study confirms that the elderly population can be a phase of growth, personal realization and continued development, without disrespecting the heterogeneous and the subjectivity of the person who ages. Notifying those healthy and well-succeeded aging experiences, this issue has the intention to contribute to demystify the concept of aging as a social problem, illness needed to be treated, and the stereotypy of the elderly being dependent and unproductive

Pistas orgânicas: uma atividade lúdica para o ensino das funções orgânicas

Educational games can work as a complementary tool in teaching and learning chemistry, playing an important role in the development of the students cognitive structures, familiarizing them with certain conceptual content, which may arouse interest in the study of such content. In this work, we made an analysis of organic chemistry textbooks recommended by Programa Nacional do Livro Didático 2012, for high school students in order to verify the existence of methodological proposals using educational games. From this analysis, we proposed an educational game to be developed for students on 3º year of high medium and undergraduate chemistry, that are in 1º semester of the course, which is constituted of a tray and 48 letters, which work various concepts concerning organic functions, such as: structural characteristics, physical properties, chemical and properties diverse of the compounds used for the confection of the letters. The game was applied to a class degree in chemistry, period 2012.1 to a Federal Education of Rio Grande do Norte and a group of students of the 3rd year of the state schools of Rio Grande do Norte, in the period the months of April and May 2012. The analysis of the performance of the game proposed was made using visual observations, photographic records and testimonials of students who participated in the games. The instrument used for the data collection was the student questionnaire, which was similar for both groups, differing only in the amount of questions, because one of them had one more question. During application of the game it was observed that it constitutes a dynamic strategy in the teaching and learning of chemistry concepts, given that students actively participated in the classes as well, demonstrated more motivation in the construction of concepts, furthermore, it was possible to observe evidence of other possibilities of the game. This could be verified through visual observations and testimonials at the end of each game, by reading the answers to the questionnaires

Atividade biológica de células-tronco da polpa de dentes decíduos humanos submetidas à criopreservação

Dental pulp stem cells have been widely investigated because of their ability to differentiate into both dental and non-dental cells, with potential use in therapies involving tissue engineering. The technique of cell cryopreservation represents a viable alternative for the conservation of these cells, since it stops reversibly, in a controlled manner, all of cell biological functions in an ultra low temperature. The present study aimed to evaluate, using in vitro experiments, the influence of a cryopreservation protocol on the biologic acti vity of stem cells from human exfoliated deciduous teeth (SHED). Cells obtained from the pulp of three deciduous teeth on end-stage exfoliation or with indicated extraction were expanded in α-MEM culture medium supplemented with antibiotics and 15% fetal bovine serum. At second subculture (P2), a group of cells were submitted to cryopreservation for 30 days in 10% DMSO diluted in fetal bovine serum, at -80º C, while the remind cells continued under normal conditions of cell culture. Cell proliferation was evaluated in both groups (not cryopreserved or cryopreserved) by Trypan blue stain essay at intervals of 24, 48 and 72h after plating. Cell cycle analysis of SHEDs submitted or not to the cryopreservation protocol was performed in the same intervals. Events related to cell death were studied by Annexyn V and PI expression under flow cytometry at the intervals of 24 and 72h. The presence of nuclear morphological changes was evaluated by DAPI staining at 72h interval. It was observed that both groups exhibited an upward cell proliferation curve, without considerable changes in cell viability throughout the experiment. The distribution of cell in the cell cycle phasis was consistent with cell proliferation in both groups. There were no nuclear morphological damages in the end range of the experiment. therefore, it is concluded that the proposed cryopreservation protocol is efficient for storing the studied cell type, allowing its use in future experimental studies

A utilização da informação contábil na atividade pecuária do Estado do Rio Grande do Norte: um enfoque nos demonstrativos gerados para tomada de decisão

This work deals with the cattle raising activity in Brasil, it´s importance for the stete of Rio Grande do Norte. A conceptual review is done regarding accounting information and considering it as an essencial input for economical and finantial decision making, related to the state cattle rainsing environment. It also aims to expose visions related to the role and the importance of Accounting as system that colects, treats and supplies managerial information. A brief historic of Accounting is done, emphasizing the Accounting Demonstration Structure and its use in the decision making process, as well as the contribution it has node for the cattle raising activity in Brazil. The research´s results show that accounting information is used partially in the finantial decision making process, and it is pointed out that the Inventory was the most relevant tool with 95,% of the cases, followed by the Income and Outlay reports with 85.0%,Production with 82,0% and Cost reports with 80,0%, the Demonstrative of the Cash Flow (DFC) with 82.5%, the Patrimonial Balance (PB) with 22.5%, and the Demonstrative of the Exercise Result (DER) with 20.0% of use. The research concludes that Accounting information is not throughly used in the economic and finantial decision making of the managers of cattle raising in the Rio Grande do Norte State, although, 95% of the sample consider then important. This may imply that there are diffilculties in measurement of the managerial decisions as well as the business whole

Análise da atividade turística desenvolvida na área de proteção ambiental dos Recifes de Corais RN

The protected areas are created for conservation to nature. The way they associate with the communities and visitors are essential to its objectives are achieved. This study aims to analyze how tourism is developed in the. The Recifes dos Corais Protected Area (APARC) through the identification of the image that tourists and residents have with respect to Parracho of Maracajaú and knowledge of the factors that contribute to a satisfactory visit of tourists. For this was an exploratorydescriptive study with quali-quantitative approach, with 236 tourists and 70 residents of the district of Maracajaú, using questionnaires and interviews. Data analysis techniques were used and percentage of arithmetic, factor analysis and content analysis. The results showed that the importance and significance attributed by residents to Parracho related to economic gains. Information on the APARC and on their standards are not done efficiently and contribute to negatively impact the site. The profile of tourists is not the most appropriate for a protected area. The dimensions of satisfaction to the tourists demonstrated the need for actions to be undertaken by the administration of APARC. Conclude that the image that the residents and tourists have of APARC is not conducive to the image of a protected areas. The tourists are satisfied with the tour in APARC, however, the dimensions of satisfaction are not consistent with the conservation of the site

Doenças respiratórias associadas à atividade de mineração no município de Parelhas, região do seridó norte-riograndense

This work aims to characterize the workers in mineral activities exposed to lung injuries in Parelhas Municipality, Rio Grande do Norte State, seeking to relate respiratory diseases to the mining activity. The studied area (Parelhas City), with about 19,700 inhabitants, is located in the Serido region, approximately 232 km far from Natal City. The number of people involved in informal mining activity (garimpo) in the Seridó region reaches about 5,000. These workers generally do not use any kind of individual protection equipments and develop, at early ages of greater productivity, severe forms of diseases, which end up disabling them to professional activities, family and social life. Deceases by respiratory problems (e.g. silicosis) have been reported in very young adults. A descriptive observational study was conducted based on information from the records found in Dr. José Augusto Dantas Hospital, between the years 1996- 2006. The occupational and socio-economic features of the population, which was selected by using the hospital records, were achieved through individually answered forms. The purpose was to link the occupational activities with the respiratory diseases. The next stage of the research was an observational case-control study, in the 1:1 proportion. The achieved data allowed confirming the central hypothesis of the research, which states that the pneumoconiosis cases are due to the mineral-based activities in the studied area. The final step of the investigation tried to assess the knowledge of relatives of students in public and private elementary and high schools from Parelhas City, regarding silicosis. About 15.4% of urban schools were analyzed through application of a structured questionnaire. The results show distinct socio-economic levels and a difference in the perception of the relatives of students in public and private schools, concerning silicosis. It was possible to identify the characteristics of the population economically involved with mineral-based activities and to define the group that deserves preferential attention in preventive actions. The work indicates some environmental problems caused by inadequate mining operations in the region

Influencia do turismo sobre a atividade pesqueira do município de Tibal do Sul-RN

A área da pesquisa localiza-se no município de Tibau do Sul, situado na costa leste do Estado do Rio Grande do Norte, a 80 km ao Sul da capital Natal. O turismo, a pesca esportiva e instalação de empreendimentos vêm aumentando nessa área litorânea, disputando espaços com pescadores artesanais. A dissertação teve como objetivo identificar e analisar os conflitos socioeconômicos e ambientais entre a atividade pesqueira e a atividade turística no Município de Tibau do Sul, para subsidiar órgãos governamentais e entidades ligadas ao setor pesqueiro, com futuras políticas de incentivo e desenvolvimento sustentável local. O presente trabalho está dividido em introdução e dois capítulos. A introdução apresenta proposta e justificativa da pesquisa, com fundamentação teórica, em seguida são apresentados os procedimentos metodológicos. O primeiro capítulo apresenta a caracterização da pesca artesanal e o perfil socioeconômico dos pescadores de Tibau do Sul, identificando os conflitos entre a atividade pesqueira e o turismo. Para alcançar esse propósito, foram realizados levantamentos qualitativos e quantitativos, através da efetivação de 100 entrevistas com questionários semiestruturados, os quais foram aplicados a quatro comunidades pesqueiras. Os resultados constataram a real situação da pesca artesanal local e foram identificados vários conflitos, dentre eles: a falta de investimento no setor, baixo desenvolvimento tecnológico e de infraestrutura, além da ocupação desordenada em área de desembarque da produção. Todos esses fatores têm contribuído para o declínio da atividade pesqueira nesse município. O segundo capítulo apresenta uma análise territorial a partir da elaboração do mapa de ocupação do solo utilizando a metodologia de geoprocessamento. Constatou-se que a ocupação desordenada ocorreu principalmente depois da chegada dos turistas em Tibau do Sul e está concentrada principalmente na praia de Pipa, observou-se também que os empreendimentos construídos na área de estudo interferem no acesso público as praias e área de desembarque da produção dos pescadores. Espera-se que este estudo contribua para elaboração do plano de manejo nas comunidades pesqueiras e possa subsidiar os gestores na implementação de políticas públicas voltadas para o desenvolvimento sustentável local

O desenvolvimento da indústria da reciclagem dos materiais no Brasil: motivação econômica ou benefício ambiental conseguido com a atividade?

A indústria de reciclagem vem se desenvolvendo no Brasil desde o começo dos anos noventa, o que resulta em elevados índices de reciclagem e tecnologia de ponta na reciclagem de alguns materiais. Requisitada como estratégia para a gestão dos resíduos no destino final, a reciclagem possui a particularidade de ser uma atividade econômica bastante rentável. Este artigo analisa os índices da indústria de reciclagem dos materiais no Brasil. Com base nos resultados obtidos através da consulta bibliográfica e dados estatísticos oriundos de fontes primárias e secundárias, conclui-se que a atividade da reciclagem dos materiais no Brasil se presta a satisfazer exclusivamente às demandas econômicas do setor. Neste sentido, a contribuição ambiental da reciclagem perde relevância visto que o crescimento da atividade está condicionado às demandas da cadeia produtiva industrial

Atividade antiinflamatória de uma heterofucana da alga marrom Padina gymnospora

Fucans, sulfated polysaccharides extracted from brown algae and some echinoderms, have been extensively studied for its diverse biological activities and because of its interference with molecular mechanisms of cell to cell recognition, including leukocyte trafficking from blood vessels into sites of inflammation mediated by selectin, a family of adhesion molecules. In the present study, we examined structural features of a heterofucan extracted from brown algae Padina gymnospora and its effect on the leukocyte migration to the peritoneum. The sulfated polysaccharides were extracted from the brown seaweed by proteolysis with the proteolytic enzyme maxatase. The presence of protein and uronic acid contamination was detected in the crude polysaccharide extract. Fractionation of the crude extract with growing concentrations of acetone produced five fractions with different concentrations of fucose, xylose, uronic acid, galactose, glucose and sulfate. The fraction precipitated with 1.5 volumes of acetone was characterized by infrared and nuclear magnetic resonance, through which can be observed the presence of sulfate groups in the C4 of -L-fucose. The anti-inflammatory action of this composite was assessed by a sodium thioglycollate-induced peritonitis assay and through nitric oxide production by the peritoneal macrophages using Griess reagent. Fraction F1.5 was efficient in reducing leukocyte influx into the peritoneal cavity when 10 mg/kg and 25mg/kg were used, resulting in a decrease of 56 and 39%, respectively. A decrease of nitric oxide production occurred when high concentrations of fucana were used. The cytotoxicity of the composite was also assessed using the reduction of 3-(4,5 dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT). Fraction F1.5 had no cytotoxicity when 500 μg/mL of the fraction was used. This study suggests the use of fraction F1.5 (heterofucan) as an anti-inflammatory

Atividade cromosférica induzida por planetas extrasolares gigantes

In the present work, we have analyzed the behavior of the chromospheric activity of stars with planets, as a function of different planetary parameters, searching for possible effects of planets on the chromosphere of the hosting star. For this study we have selected a sample of 73 main sequence stars with planets, of spectral types F, G and K. Our analysis shows that among stars with planets presenting semi-major axis smaller than 0.15 AU, a few ones present enhanced CaII emission flux, paralleling recent results found in the literature for coronal X-ray flux. Nevertheless, in contrast to Kashyap et al. (2008), who claim that enhanced X-ray flux in stars with planets is associated to massive close-in planetary companions, we suggest that such an aspect, at least in the context of CaII emission flux, is rather an effect of stellar sample selection. We have also studied the behavior of the CaII emission as a function of orbital parameters such as orbital period and eccentricity, and no clear trend was found, reinforcing our present suggestion that enhanced chromospheric activity in stars with planets is an intrinsic stellar phenomenon

Efeitos da laserterapia na atividade biológica de células de carcinoma epidermóide de língua humano

The low level laser therapy (LLLT) has shown to be effective in promoting the proliferation of different cells in vitro, including keratinocytes, osteoblasts, endothelial cells and stem cells. It has been speculated that the biostimulatory effect of LLLT could cause undesirable enhancement of tumor growth in neoplastic diseases, since the malignant cells are more susceptible to proliferative stimuli. Within this context, this study evaluated the effect of LLLT on epidermoid carcinoma of the tongue cell line (SCC25) proliferation and invasion. Cultured cells were irradiated with an InGaAIP diode laser, 660nm, 30mW using two energy densities (0.5J/cm2 and 1.0J/cm2). Proliferative activity was assessed through trypan blue staining method and through cell cycle analysis using flow cytometry. The invasive potential was measured through cell invasion assay using matrigel. Cyclin D1, E-cadherin, -catenin and MMP-9 expressions were analyzed by immunofluorescence and flow cytometry and related to the investigated biological activities. Proliferation curve demonstrated that SCC25 irradiated with 1.0J/cm2 had the highest proliferative rate when compared to the control group and the group irradiated with 0.5J/cm2 (p<0.05). LLLT affected cell cycle distribution and energy density of 1.0 J/cm2 promoted a higher percentage of cells in S/G2/M phases, with statistically significant differences at 24h interval (p<0.05). LLLT, mainly with 1.0J/cm2, revealed significantly higher potential for invasion and influenced the expression of cyclin D1, E-cadherin, -catenin and MMP-9, promoting the malignant phenotype. In conclusion, our results indicate that LLLT has an important stimulatory effect on proliferation and invasion of SCC25 cells, likely due to altered expression of proteins associated with these processes

Estudo da atividade sísmica em São Caetano-PE em 2007

In this dissertation we studied the seismic activity in the São Caetano county, Pernambuco State, Northeastern Brazil, located near the Pernambuco Lineament. The Pernambuco Lineament is a one of Neoproterozoic continental-scale shear zones that deforms the Borborema province. The seismicity estudied occurred in a NE trending branch of Pernambuco Lineament. The seismic activity in São Caetano started in 2006 and in May 20th, 2006 a 4,0 mb earthquake hit there. This was the largest earthquake ever reported in Pernambuco State. This dissertation is the result of a campaign done in the period from Februay 1th 2007 to July 31 th 2007. In this campaign up to nine three-component digital seismographic stations were deployed and the collected data was used to determine hypocenters and focal mechanism. A total of 214 earthquakes, recorded at least by three stations, were analyzed. To determine hypocenters and time origin the HYPO71 program was used assuming a half-space model with parameters : VP (P-wave velocity) equal to 5.90 km/s and the ratio VP/VS 1.70, where VS is the S-wave velocity. The earthquakes hypocentral distribution was approximately 4 km long and agrees with the NE-SW direction of the Pernambuco Lineamento branch. Hypocentres depth range from 2 to 8 km. The composed focal mechanism was made from a group of 14 selected earthquakes. We try firstly to find the fault plane solution matching the polarity distribution at stations, using the FPFIT program. The result was 43 deg ± 15 deg for strike, 59 deg ± 9 deg for dip and -142 deg ± 15 deg for rake. We also fitted a plane using the hypocentral distribution to obtain the dip and azimuth of the hypocentral distribution. The results obtained by this fit were 58 deg for the azimuth, 55 deg for the dip and -155 deg for rake. This result shows a mechanism of a strike-slip dextral fault with a normal component. This dissertation shows, once more, that there is a good correlation between the seismic activity and geological features in the region near the Pernambuco Lineament and its NE branches

A erosão costeira e sua influência sobre a atividade petrolífera: alternativas sustentáveis na mitigação de impactos ambientais

The study area consist in high sensitivity environments located on the northern coast of Rio Grande do Norte, Northeast Brazil. The barrier island are the main geomorphological features on the coastal landscape, being naturally instable and surrounded by industrial activities like oil fields, salt industry, shrimp farms and urban areas sometimes installed parallel to the coast, combined with coast engineering interventions. High energy hydrodynamic process are responsible for the morphological instability of the coast. The study was based on remote sensing data obtained between 1954 and 2007 which consist in orbital images from Landsat, CBERS and Ikonos satellites and aerial photos. With all data integrated on GIS environment it was possible to update thematic maps of geology, geomorphology, vegetation, soil and landuse and development of multitemporal maps pointing areas with erosion and depositions of sediments, defining the critical erosion process on this region. The bigger morphological changes are related to changes on wind patterns during the year, terrestrial and sea breezes during the day, with spits and barrier island migration, opening and closing of channels like the one parallel to the coast on the area of Serra and Macau oil fields. These factors combined with the significant reduction on sediment budgets due to the loss of natural spaces to sediment reworking contribute to the low resilience which tends to be growing on the area of Serra and Macau oil fields. In front of such scenery a detailed monitoring was done in order to find technological possibilities for coastal restoration. A pilot area was defined to start the project of mangrove restore together with beach nourishment in order to minimize the effect of the erosion caused by the channel parallel to the coast, contributing to stabilize the northeast channel as the main one. It s expected that such methodology will aid the coastal environments restoration and the balance between industrial activities and coastal erosion

Das farinhadas à produção para o mercado: a dinâmica da atividade mandioqueira no agreste potiguar.

El Agreste Potiguar es el territorio de Rio Grande do Norte en que más se produce yuca. La formación de ese territorio asociase a la ganadería y al cultivo de algodón y de cultivos de autoconsumo, de entre los cuales, la yuca. En lo concerniente, específicamente al cultivo de la yuca, esa planta siempre ha sido sumamente importante para la subsistencia de los agrestinos , sobre todo, de los pobres. Hasta la década de 1980, la yuca era cultivada en pequeñas parcelas de tierra y era destinada a la fabricación de harina, que juntamente con el frijol, era la base de la alimentación de los trabajadores agrestinos. Además, era bastante útil para la producción de ración para el ganado. A partir de esa década, la actividad mandioquera (cultivo de la yuca con la transformación de ésta en harina y en otros derivados) desencadenada en el Agreste Potiguar empieza a pasar por un proceso de modernización, siendo implementadas transformaciones técnicas y en las relaciones de trabajo, bajo la lógica capitalista. Dentro de esa lógica, el cultivo de la yuca pasa a ser hecho con el uso de máquinas y de abonos químicos; la transformación en harina es actualmente realizada en manufacturas y en industrias de harina, que vienen siendo, cada vez más, marcadas por instrumentos técnicos movidos a electricidad, disminuyendo la necesidad de mano de obra; y la yuca no es más cultivada por los productores con el objetivo primordial de garantizar su subsistencia, pero sí con el de atender a la demanda por materia prima de las manufacturas y de las industrias de harina. De este modo, el objetivo del trabajo es comprender la dinámica de la actividad mandioquera en el Agreste Potiguar, considerando el uso pasado y actual del territorio, la modernización de esa actividad y su contribución al desarrollo del territorio en cuestión. Como procedimientos metodológicos, adoptamos la realización de investigaciones bibliográficas, empíricas (entrevistas y conversaciones) y el análisis de datos secundarios. Finalmente, sabiéndose que el proceso de modernización estudiado sigue la lógica capitalista, concluimos el trabajo afirmando que la modernización de la actividad mandioquera no viene contribuyendo al desarrollo territorial del Agreste Potiguar.

Circuitos espaciais de produção da atividade boneleira: o uso dos territórios de Caicó, Serra Negra do Norte e São José do Seridó

Cette étude a été fondée sur la reconaissance, la description et l'analyse du circuit spatial de la production de l activité des fabriques des casquettes dans la région du Seridó Potiguar. L activité des fabriques des casquettes est située dans les villes de Caicó, Serra Negra do Norte e São José do Seridó, qui forment le pôle de fabriques de casquettes, composé de soixante-quatre (64) unités de fabrication, le deuxième plus grand producteur de casquettes au Brésil. Dans la condition de base géographique, l'opérationnalisation du concept de circuits spatiales de la production a été essentielle à la compréhension de l'utilisation du territoire et de l'indivisibilité de l'espace, du fournisseur de matières premières au consommateur final, comprenant les étapes des matières premières, la main-d'oeuvre, le stockage, les transports, le commerce et la consommation dans la période actuelle, dans laquelle les instances de la production, la circulation, la distribution et de la consommation sont spatialement diffus. Sur la base de l'identification et de la localisation de ces étapes et des principaux acteurs impliqués dans la activité des fabriques de casquettes, une configuration de circuit spatial de la production a été élaborée, en s'interprétant l'utilisation des territoires par les instances productives. L'interprétation des étapes de production a identifié que les entreprises liées à l'Association Seridoense des Fabricants de Casquettes agissent plus efficacement sur le territoire que celles nonassociées, alors que toujours elles investissent dans des nouveaux équipements, en augmentant sa puissance technique pour se renforcer avant un marché si compétitif comme celui des casquettes. En examinant la contribution de la fabrication des casquettes à l'utilisation actuelle des territoires de la coupe, nous avons appris que les activités complémentaires et des matières premiéres nécessaires à sa réalisation se trouvent dans leur environnement géographique. Ainsi, la proximité spatiale entre les étapes de la fabrication des casquettes fait entrevoir la matérialité du territoire, conférée dans la coexistence des techniques passées et présentes, et l'ensemble des actions effectuées par un certain nombre de travailleurs sociaux qui collaborent à la création du circuit spatial de la production de l activité des fabriques des casquettes. Cette étude a confirmé que les fabriques des casquettes sont organisées sous la forme de cellules de production, continues ou discontinues, dont les équipements et les machines à coudre industrielles obéissent à la logique d'une production de plus en plus standardisée. Ce circuit spatial de la production contribue à l'utilisation actuelle des territoires de Caicó, Serra Negra do Norte et de São José do Seridó car il amplifie le mouvement du commerce et des relations entre les lieux, à travers la dynamique des flux des personnes, des biens et des produits, en constante circulation, guidées par la division du travail entre les étapes productives