Modelação sintética quantitativa de vários anos de atividade: qual é a relação entre significado na situação e complexidade longitudinal?

Um problema recorrente na investigação longitudinal sobre a atividade humana é a falta de articulação entre modelos analíticos qualitativos e modelos sintéticos quantitativos de evolução dinâmica. Esta ausência cria dificuldades na justificação das escolhas de análise e síntese e impede uma abordagem dedutiva das dinâmicas longitudinais. No âmbito de uma investigação empírica e tecnológica longitudinal de 3 anos sobre apropriação, este artigo discute as condições de produção e a utilidade de um modelo sintético quantitativo da complexidade longitudinal da atividade individual, em articulação com um método analítico qualitativo. Mais do que a mobilização de um modelo único de dados prévios, o trabalho de modelação envolve uma articulação ativa entre modelos-métodos analíticos (clássicos na análise de atividade) e modelos-métodos sintéticos. Discutimos as contribuições e limites deste trabalho no que diz respeito à análise da atividade na ergonomia de língua francesa e as ciências da complexidade mais frequentemente mobilizadas em fatores humanos.Un problema recurrente en la investigación longitudinal sobre la actividad humana es la falta de articulación entre los modelos analíticos cualitativos y los modelos sintéticos cuantitativos de la evolución dinámica. Esta ausencia crea dificultades para justificar las opciones de análisis y síntesis e impide un enfoque deductivo de la dinámica longitudinal. En el marco de una investigación empírica y tecnológica longitudinal de tres años sobre la apropiación, este artículo analiza las condiciones de producción y la utilidad de un modelo sintético cuantitativo de la complejidad longitudinal de la actividad individual, junto con un método analítico cualitativo. Más que la movilización de un único modelo de datos previo, la labor de modelización supone una articulación activa entre los métodos de modelos analíticos (clásicos en el análisis de actividades) y los métodos de modelos sintéticos. Discutimos las contribuciones y los límites del presente trabajo con respecto al análisis de la actividad efectuado por la ergonomía de lengua francesa y a las ciencias de la complejidad que se movilizan más a menudo en los factores humanos.Un problème récurrent des recherches longitudinales sur l’activité humaine est leur absence d’articulation entre modèle analytique qualitatif et modèle synthétique quantitatif d’évolution dynamique. Cette absence engendre des difficultés dans la justification des choix d’analyse et de synthèse et empêche d’aboutir à une démarche déductive sur les dynamiques longitudinales. Dans le cadre d’une recherche empirique et technologique longitudinale de 3 ans sur l’appropriation, cet article discute des conditions de production et de l’utilité d’une modélisation synthétique quantitative de la complexité longitudinale de l’activité individuelle, en articulation avec une méthode analytique qualitative. Plus que la mobilisation d’un modèle seul et pré-donné, le travail de modélisation relève d’une articulation active entre méthodes-modèles analytiques (classiques en analyse d’activité) et méthodes-modèles synthétiques. Nous discutons des apports et limites de ce travail vis-à-vis de l’analyse de l’activité en ergonomie de langue française et des sciences de la complexité plus souvent mobilisées dans les facteurs humains.A recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence creates difficulties in justifying the choices of analysis and synthesis and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this paper discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modeling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. We discuss the contributions and limits of this work with respect to activity analysis in French-language ergonomics and the complexity sciences more often mobilized in human factors

Modélisation synthétique quantitative de plusieurs années d’activité. Quelle articulation entre signification en situation et complexité longitudinale ?

Un problème récurrent des recherches longitudinales sur l’activité humaine est leur absence d’articulation entre modèle analytique qualitatif et modèle synthétique quantitatif d’évolution dynamique. Cette absence engendre des difficultés dans la justification des choix d’analyse et de synthèse et empêche d’aboutir à une démarche déductive sur les dynamiques longitudinales. Dans le cadre d’une recherche empirique et technologique longitudinale de 3 ans sur l’appropriation, cet article discute des conditions de production et de l’utilité d’une modélisation synthétique quantitative de la complexité longitudinale de l’activité individuelle, en articulation avec une méthode analytique qualitative. Plus que la mobilisation d’un modèle seul et pré-donné, le travail de modélisation relève d’une articulation active entre méthodes-modèles analytiques (classiques en analyse d’activité) et méthodes-modèles synthétiques. Cette articulation offre des perspectives d’amélioration des études longitudinales centrées sur l’activité humaine et fournit des supports visuels utiles en projet de conception. Nous discutons des apports et limites de ce travail vis-à-vis de l’analyse de l’activité en ergonomie de langue française et des sciences de la complexité plus souvent mobilisées dans les facteurs humains.One recurring problem in longitudinal research on human activity is the lack of articulation between qualitative analytical models and quantitative synthetic models of the dynamic evolution. This absence makes it difficult to justify analysis and synthesis choices and prevents a deductive approach to longitudinal dynamics. Within the framework of a 3-year longitudinal empirical and technological research on appropriation, this article discusses the conditions of production and the usefulness of a quantitative synthetic model of the longitudinal complexity of individual activity, in conjunction with a qualitative analytical method. More than the mobilization of a single, pre-data model, the modelling work involves an active articulation between analytical model-methods (classical in activity analysis) and synthetic model-methods. This linkage offers prospects for improving longitudinal studies centred on human activity and provides useful visual support for design projects. We discuss the contributions and limits of this work with respect to activity analysis in French-language ergonomics and the complexity sciences most often mobilized in human factors

Development and hormonal functions of the human placenta.

The human placenta is characterized by the intensity of the trophoblast invasion into the uterus wall and the specificity of its hormonal functions. Placental hormones are required for the establishment and maintenance of pregnancy, adaptation of the maternal organism to pregnancy and fetal growth. In the early placenta at the maternofetal interface, the human trophoblast differentiates along two pathways: 1/ the villous trophoblast pathway including the cytotrophoblastic cells which differentiate by fusion to form the syncytiotrophoblast that covers the entire surface of the villi; 2/ the extravillous trophoblast pathway. The cytotrophoblastic cells of the anchoring villi in contact with the uterus wall proliferate and then migrate into the decidua and the myometrium but also participate to the remodeling of the spiral arteries. During the first trimester of pregnancy the spiral arteries are plugged by trophoblastic cells, allowing the development of the fetoplacental unit in low oxygen environment. At this stage of pregnancy the extravillous trophoblast secretes a large amount of hormones such as particular hyperglycosylated forms of hCG directly involved in the quality of the placentation. At 10-12 weeks of pregnancy, the trophoblastic plugs are progressively dislocated and the syncytiotrophoblast starts to bath in maternal blood. It secretes the major part of its polypeptide hormones in maternal circulation taking over the maternal metabolism in order to increase the energetic flux to the fetus. As example the placental GH (growth hormone) secreted continuously by the syncytiotrophoblast is directly involved in the insulino-resistance of pregnancy. Capturing the cholesterol from the maternal lipoproteins, the syncytiotrophoblast synthesizes also large amount of progesterone essential for the uterine quiescence. Deprived of cytochrome P450 17alpha-hydroxylase-17:20 lyase, it uses the maternal and fetal adrenal androgens to synthesize estrogens. The differentiation and hormonal functions of the human trophoblast are regulated by the environmental O2 and reflect mammalian evolution

Development and hormonal functions of the human placenta.

The human placenta is characterized by the intensity of the trophoblast invasion into the uterus wall and the specificity of its hormonal functions. Placental hormones are required for the establishment and maintenance of pregnancy, adaptation of the maternal organism to pregnancy and fetal growth. In the early placenta at the maternofetal interface, the human trophoblast differentiates along two pathways: 1/ the villous trophoblast pathway including the cytotrophoblastic cells which differentiate by fusion to form the syncytiotrophoblast that covers the entire surface of the villi; 2/ the extravillous trophoblast pathway. The cytotrophoblastic cells of the anchoring villi in contact with the uterus wall proliferate and then migrate into the decidua and the myometrium but also participate to the remodeling of the spiral arteries. During the first trimester of pregnancy the spiral arteries are plugged by trophoblastic cells, allowing the development of the fetoplacental unit in low oxygen environment. At this stage of pregnancy the extravillous trophoblast secretes a large amount of hormones such as particular hyperglycosylated forms of hCG directly involved in the quality of the placentation. At 10-12 weeks of pregnancy, the trophoblastic plugs are progressively dislocated and the syncytiotrophoblast starts to bath in maternal blood. It secretes the major part of its polypeptide hormones in maternal circulation taking over the maternal metabolism in order to increase the energetic flux to the fetus. As example the placental GH (growth hormone) secreted continuously by the syncytiotrophoblast is directly involved in the insulino-resistance of pregnancy. Capturing the cholesterol from the maternal lipoproteins, the syncytiotrophoblast synthesizes also large amount of progesterone essential for the uterine quiescence. Deprived of cytochrome P450 17alpha-hydroxylase-17:20 lyase, it uses the maternal and fetal adrenal androgens to synthesize estrogens. The differentiation and hormonal functions of the human trophoblast are regulated by the environmental O2 and reflect mammalian evolution

Overexpression of copper zinc superoxide dismutase impairs human trophoblast cell fusion and differentiation.: SOD-1 and Human Trophoblast Differentiation

The syncytiotrophoblast is the major component of the human placenta, involved in feto-maternal exchanges and secretion of pregnancy-specific hormones. Multinucleated syncytiotrophoblast arises from fusion of mononuclear cytotrophoblast cells. In trisomy 21-affected placentas, we recently have shown that there is a defect in syncytiotrophoblast formation and a decrease in the production of pregnancy-specific hormones. Due to the role of oxygen free radicals in trophoblast cell differentiation, we investigated the role of the key antioxidant enzyme, copper/zinc superoxide dismutase, encoded by chromosome 21 in in vitro trophoblast differentiation. We first observed that overexpression of superoxide dismutase in normal cytotrophoblasts impaired syncytiotrophoblast formation. This was associated with a significant decrease in mRNA transcript levels and secretion of hCG and other hormonal markers of syncytiotrophoblast. We confirmed abnormal cell fusion by overexpression of green fluorescence protein-tagged superoxide dismutase in cytotrophoblasts. In addition, a significant decrease in syncytin transcript levels was observed in superoxide dismutase-transfected cells. We then examined superoxide dismutase expression and activity in isolated trophoblast cells from trisomy 21-affected placentas. Superoxide dismutase mRNA expression (P < 0.05), protein levels (P < 0.01), and activity (P < 0.05) were significantly higher in trophoblast cells isolated from trisomy 21-affected placentas than in those from normal placentas. These results suggest that superoxide dismutase overexpression may directly impair trophoblast cell differentiation and fusion, and superoxide dismutase overexpression in Down's syndrome may be responsible at least in part for the failure of syncytiotrophoblast formation observed in trisomy 21-affected placentas

Biochemical characterization and modulation of LH/CG-receptor during human trophoblast differentiation.: LH/CG-R in human trophoblast differentiation.

Due to the key role of the human chorionic gonadotropin hormone (hCG) in placental development, the aim of this study was to characterize the human trophoblastic luteinizing hormone/chorionic gonadotropin receptor (LH/CG-R) and to investigate its expression using the in vitro model of human cytotrophoblast differentiation into syncytiotrophoblast. We confirmed by in situ immunochemistry and in cultured cells, that LH/CG-R is expressed in both villous cytotrophoblasts and syncytiotrophoblasts. However, LH/CG-R expression decreased during trophoblast fusion and differentiation, while the expression of hCG and hPL (specific markers of syncytiotrophoblast formation) increased. A decrease in LH/CG-R mRNA during trophoblast differentiation was observed by means of semi-quantitative RT-PCR with two sets of primers. A corresponding decrease ( approximately 60%) in LH/CG-R protein content was shown by Western-blot and immunoprecipitation experiments. The amount of the mature form of LH/CG-R, detected as a 90-kDa band specifically binding (125)I-hCG, was lower in syncytiotrophoblasts than in cytotrophoblasts. This was confirmed by Scatchard analysis of binding data on cultured cells. Maximum binding at the cell surface decreased from 3,511 to about 929 molecules/seeded cells with a kDa of 0.4-0.5 nM. Moreover, on stimulation by recombinant hCG, the syncytiotrophoblast produced less cyclic AMP than cytotrophoblasts, indicating that LH/CG-R expression is regulated during human villous trophoblast differentiation. J. Cell. Physiol. 212: 26-35, 2007. (c) 2007 Wiley-Liss, Inc

Outbreak of Serogroup W135 Meningococcal Disease after the Hajj Pilgrimage, Europe, 2000

The 2000 Hajj (March 15–18) was followed by an outbreak of Neisseria meningitidis W135 2a: P1.2,5 in Europe. From March 18 to July 31, 2000, some 90 cases of meningococcal infection were reported from nine countries, mostly the United Kingdom (UK) and France; 14 cases were fatal. Although most early cases were in pilgrims, the outbreak spread to their contacts and then to those with no known pilgrim contact. In France and the UK, the outbreak case-fatality rate was compared with the rate reported from national surveillance. The risk of dying during this outbreak was higher in France and the UK, although the difference was not statistically significant. Prophylaxis for all pilgrims and their household contacts was offered in France; in the UK and other European countries, prophylaxis was recommended only for close contacts. No difference in transmission rates following intervention was detected between France and the UK

High-amplitude water-level fluctuations at the end of the Mediterranean Messinian Salinity Crisis: Implications for gypsum formation, connectivity and global climate

The formation and dissolution of salt giants impacts ocean chemistry on thousand-million year timescales. Gypsum precipitation and weathering changes the oceanic calcium concentration with implications for the carbon cycle and global temperatures. However, the connectivity of salt giants with the global ocean is necessarily restricted, making the timing of Ca2+ extraction and return more uncertain. Here we reconstruct the final phase of gypsum precipitation of the Late Miocene Mediterranean Salt Giant using micropaleontology, sedimentology and 87Sr/86Sr analyses on the most complete record preserved at Eraclea Minoa on Sicily and explore its implications for global climate. Precessional gypsum-marl couplets (Upper Gypsum) characterize the last 200 kyrs (Stage 3) of the Messinian Salinity Crisis (MSC; 5.97–5.332 Ma) in both intermediate (500–1000 m) and deep (>1000 m) Mediterranean basins. The interbedded selenitic gypsum layers contain well-preserved calcareous nannofossil assemblages dominated by Reticulofenestra minuta, a marine species which tolerates stressful conditions. Marine water is also required to explain the gypsum 87Sr/86Sr data, which describe a small range of ratios (0.708704–0.708813) lower than coeval ocean water. Mass-balance calculations indicate that during gypsum precipitation, the Atlantic made up ≤20% of a Mediterranean (“Lago-Mare”) water mass dominated by low salinity discharge from large river systems and Eastern Paratethys. This suggests episodic extraction of calcium and sulfate ions from the ocean throughout MSC Stage 3. The marls commonly contain shallow (30–100 m) brackish-water ostracods of Paratethyan (Black Sea) origin. Marls with Paratethyan ostracods are also found in both marginal (<500 m) and deep Mediterranean settings. This indicates that marl-deposition was not synchronous across the basin, but that it occurred in intermediate and deep basins during base-level lowstands at insolation minima and on the shallow Mediterranean margins during insolation maxima-driven highstands. These high-amplitude base-level fluctuations exposed the evaporites to weathering, but ponded the products in the Mediterranean basin until reconnection occurred at the beginning of the Pliocene

Freshening of the Mediterranean Salt Giant: controversies and certainties around the terminal (Upper Gypsum and Lago-Mare) phases of the Messinian Salinity Crisis

The late Miocene evolution of the Mediterranean Basin is characterized by major changes in connectivity, climate and tectonic activity resulting in unprecedented environmental and ecological disruptions. During the Messinian Salinity Crisis (MSC, 5.97-5.33 Ma) this culminated in most scenarios first in the precipitation of gypsum around the Mediterranean margins (Stage 1, 5.97-5.60 Ma) and subsequently &gt; 2 km of halite on the basin floor, which formed the so-called Mediterranean Salt Giant (Stage 2, 5.60-5.55 Ma). The final MSC Stage 3, however, was characterized by a "low-salinity crisis", when a second calcium-sulfate unit (Upper Gypsum; substage 3.1, 5.55-5.42 Ma) showing (bio)geochemical evidence of substantial brine dilution and brackish biota-bearing terrigenous sediments (substage 3.2 or Lago-Mare phase, 5.42-5.33 Ma) deposited in a Mediterranean that received relatively large amounts of riverine and Paratethys-derived low-salinity waters. The transition from hypersaline evaporitic (halite) to brackish facies implies a major change in the Mediterranean’s hydrological regime. However, even after nearly 50 years of research, causes and modalities are poorly understood and the original scientific debate between a largely isolated and (partly) desiccated Mediterranean or a fully connected and filled basin is still vibrant. Here we present a comprehensive overview that brings together (chrono)stratigraphic, sedimentological, paleontological, geochemical and seismic data from all over the Mediterranean. We summarize the paleoenvironmental, paleohydrological and paleoconnectivity scenarios that arose from this cross-disciplinary dataset and we discuss arguments in favour of and against each scenario