206 research outputs found
Empowerment zones and the housing market in paris inner city
We test for the impact of local enterprise zones on house prices in inner Paris. In 1997, a new urban policy program was launched in France which created three kinds of Enterprise Zones (ZUS, ZRU and ZFU). Notably, 9 first tier EZs (ZUS) were created in Paris. We use this natural experiment and compare the evolution of flat prices in these areas to that in a control group of neighboring areas (that could also have been converted into ZUS). We develop a new semi-parametric spatial matching methodology. Each sale observed be-fore the reform is matched with a similar post-reform counterfactual. This matching procedure is done for housing units within the EZ, as well as for units in the vicinity of the EZ. In contrast to what have been evidenced in other ad-ministrative districts of the Paris Region and for other kinds of EZs (i.e., ZFUs), we detect no significant effect of this expensive EZ program implementation on housing values
Stanislas Meunier (1843-1925) et la controverse sur le creusement des « puits naturels du calcaire ». L’apport de la géologie expérimentale
À la fin du XIXe siècle, Stanislas Meunier (1843-1925), professeur au muséum d’Histoire Naturelle, développe la géologie expérimentale. Il est sans doute le seul à tester les processus érosifs et s’intéresse notamment au creusement des cavernes et des puits naturels du calcaire. Sa théorie est basée sur l’expérimentation. Par un jet acide, ascendant ou descendant, il cherche à reproduire les phénomènes de la nature et génère ainsi des formes de dissolution sur des maquettes calcaires de dimensions modestes (une dizaine de centimètres). Les formes coniques obtenues, en entonnoir (jet descendant) ou en éteignoir (jet ascendant), lui permettent d’ébaucher des lois sur le rôle des fluides (d’origine météorique ou d’origine profonde) dans le creusement des puits naturels du calcaire. Edouard-Alfred Martel (1859-1938) est à ce moment-là un jeune explorateur des mondes souterrains. Son approche est naturaliste. Il observe des puits naturels et les topographies. Il réfute les assertions de Meunier. Une controverse, étalée sur une vingtaine d’années, nourrira une bibliographie analysée ici. Au début du XXe siècle chacun des protagonistes reconnaît la qualité du travail de l’autre et ils se citent de manière croisée. A travers cet exemple, on mesure combien ces approches naturalistes d’un côté, expérimentale de l’autre, ont nourri des réflexions fécondes sur les processus morphogéniques en œuvre dans la karstification.At the end of the 19th century, Stanislas Meunier (1843-1925), professor at the Museum of Natural History in Paris, developed experimental Geology. He is probably the only one to test the erosive processes. He is particularly interested in digging caverns and limestone natural wells. His theory is based on experimentation. With an acid jet, ascending or descending, he tries to reproduce the natural phenomena and thus generates forms of dissolution on limestone models (small dimensions, about ten centimeters). The conical shapes obtained, as a funnel (downward jet) or as a snuffer (upward jet), allow him to propose laws on the fluids effect (meteoric or deep origin) in the digging of natural limestone wells. At this time, Edouard-Alfred Martel (1859-1938) is a young speleologist. His approach is naturalistic. He observes natural wells and surveys the caves. He refutes Meunier’s assertions. A controversy, spread over twenty years, gives us a bibliography analyzed here. At the beginning of the 20th century, each of the protagonists recognized the quality of the work of the other by cross-referencing. Through this example, we measure how these naturalistic and experimental approaches, fed fertile reflections on the morphogenic processes for the karstification
Uloga enzima u metabolizmu ugljikohidrata pri diferencijaciji staničnih linija šećerne repe
Plant development is influenced by changes in the levels and types of sugars produced metabolically. The normal (N), habituated organogenic (HO) and habituated nonorganogenic (HNO) sugar beet cell lines originate from the same mother plant but exhibit distinct levels of morphogenesis and differentiation, and contain different levels of simple carbohydrates. We aim to elucidate whether differences in the abundance and activity of enzymes involved in carbohydrate metabolism and sugar sensing/signalling help explain the different carbohydrate profiles and differentiation states of the cell lines. Using 13C NMR spectroscopy to analyze cultures of the cell lines over 28 days, we found that N cells accumulated sucrose; HO cells sucrose, glucose and fructose; and HNO cells glucose and fructose. Of three invertase isoforms, the activity of cell wall invertase (CWI) was highest in all the cell lines, and CWI activity was greatest in HNO line. The specific accumulation of intracellular carbohydrates during subculture correlated strongly with CWI activity but less so with the vacuolar and cytoplasmic invertase isoforms, or with sucrose synthase activity. Cell lines showed differences in how sugars regulated invertase and sucrose synthase activity. The role of sugar sensing in the regulation of CWI activity was investigated in the cell lines using glucose and sucrose, as well as carbohydrate analogues such as mannitol, 2-O-deoxyglucose and 3-O-methylglucose. Differences in the regulation of CWI activity by carbohydrates across the three cell lines suggest that CWI can be fine-tuned according to the specific carbohydrate requirements of each line during growth. Differences in sugar signalling pathways across the cell lines were explored using glucose and sucrose in the presence of inhibitors of protein kinases or phosphatases. Taken together, our findings suggest that specific regulation of CWI activity plays an important role in determining the intracellular carbohydrate levels of sugar beet cell lines, and possibly their differentiation state as well.Na razvoj biljke utječu promjene razine i tipa proizvedenog šećera. Iako sve stanične linije šećerne repe, i to normalna, prilagođena organogena i prilagođena neorganogena potječu od iste biljke, na različitim su stupnjevima diferencijacije i morfogeneze te sadrže različitu količinu jednostavnih ugljikohidrata. Svrha je rada bila utvrditi može li se razlikama u količini i aktivnosti enzima, koji sudjeluju u metabolizmu šećera te onih u detekciji i prijenosu signala šećera, objasniti razlika u stupnju diferencijacije staničnih linija te u udjelu ugljikohidrata u njima. Primjenom 13C NMR spektroskopije analizirane su stanične linije tijekom 28 dana kultivacije i ustanovljeno je da normalne stanične linije akumuliraju saharozu, prilagođena organogena stanična linija saharozu, glukozu i fruktozu, a prilagođena neorganogena stanična linija šećerne repe glukozu i fruktozu. Od 3 izoformna oblika invertaze najveća je aktivnost invertaze stanične stijenke u sve 3 stanične linije, osobito u prilagođenih neorganogenih stanica. Specifičnost akumulacije ugljikohidrata u stanici tijekom kultivacije uvelike je ovisila o aktivnosti invertaze stanične stijenke, a manje o onoj vakuolarne i citoplazmatske invertaze te saharoza sintetaze. Šećeri su različito regulirali aktivnost invertaze stanične stijenke i saharoza sintetaze, ovisno o tipu stanične linije. Njihova je uloga istražena pomoću glukoze i saharoze te njihovih analoga, kao što su manitol, 2-O-deoksiglukoza i 3-O-metilglukoza. Utvrđeno je da se aktivnost invertaze stanične stijenke može fino regulirati pomoću ugljikohidrata, ovisno o potrebi staničnih linija za izvorom šećera tijekom rasta. Razlike u putovima prijenosa signala šećera u staničnih linija istražene su pomoću glukoze i saharoze u prisutnosti inhibitora protein kinaza i fosfataza. Na kraju, rezultati autora potvrđuju da specifična regulacija aktivnosti invertaze stanične stijenke ima važnu ulogu u određivanju razine ugljikohidrata u staničnim linijama šećerne repe, a možda i stupnju diferencijacije stanica
Ivy : un bus logiciel au service du développement de prototypes de systèmes interactifs
Ce document présente l'expérience acquise au cours du développement et de l'utilisation du bus logiciel Ivy, dans un cadre de prototypage de systèmes interactifs pour le contrôle du trafic aérien. Après une description du principe de fonctionnement de ce système, nous verrons comment cet outil a pu influer sur notre approche de problématiques IHM spécifiques comme la multimodalité, l'interaction répartie ou la mobilité. L'accent est porté sur les services rendus par ce bus pour le développement rapide de systèmes interactifs " légers ", facilement intégrables dans un banc de démonstration et basés sur la logique des langages de script. En présentant cet outil que nous utilisons depuis maintenant cinq ans, nous espérons partager ici une expérience utile pour la conception de futures architectures de systèmes interactifs à des fins de recherche prospective
A lipoxygenase with dual positional specificity is expressed in olives (Olea europaea L.) during ripening.
International audiencePlant lipoxygenases (LOXs) are a class of widespread dioxygenases catalysing the hydroperoxidation of polyunsaturated fatty acids. Although multiple isoforms of LOX have been detected in a wide range of plants, their physiological roles remain to be clarified. With the aim to clarify the occurrence of LOXs in olives and their contribution to the elaboration of the olive oil aroma, we cloned and characterized the first cDNA of the LOX isoform which is expressed during olive development. The open reading frame encodes a polypeptide of 864 amino acids. This olive LOX is a type-1 LOX which shows a high degree of identity at the peptide level towards hazelnut (77.3%), tobacco (76.3%) and almond (75.5%) LOXs. The recombinant enzyme shows a dual positional specificity, as it forms both 9- and 13-hydroperoxide of linoleic acid in a 2:1 ratio, and would be defined as 9/13-LOX. Although a LOX activity was detected throughout the olive development, the 9/13-LOX is mainly expressed at late developmental stages. Our data suggest that there are at least two Lox genes expressed in black olives, and that the 9/13-LOX is associated with the ripening and senescence processes. However, due to its dual positional specificity and its expression pattern, its contribution to the elaboration of the olive oil aroma might be considered
Excited state absorption : a key phenomenon for the improvement of biphotonic based optical limiting at telecommunication wavelengths
International audienceSpectroscopic properties, two-photon absorption (TPA) and excited state absorption (ESA), of two organic cyanine dyes and of a ruthenium based organometallic cyanine are compared in order to rationalize their similar ns-optical power limiting (OPL) efficiency in the telecommunication wavelength range. The TPA contribution to the ns-OPL behavior is higher for both organic cyanines, while the main process is a TPA-induced ESA in the case of the organometallic system, in which the ruthenium induces a broadening of the NIR-ESA band and resulting in a strong spectral overlap between TPA and ESA spectra
The Chemokine CCL2 Protects Against Methylmercury Neurotoxicity
Industrial pollution due to heavy metals such as mercury is a major concern for the environment and public health. Mercury, in particular methylmercury (MeHg), primarily affects brain development and neuronal activity, resulting in neurotoxic effects. Because chemokines can modulate brain functions and are involved in neuroinflammatory and neurodegenerative diseases, we tested the possibility that the neurotoxic effect of MeHg may interfere with the chemokine CCL2. We have used an original protocol in young mice using a MeHg-contaminated fish-based diet for 3 months relevant to human MeHg contamination. We observed that MeHg induced in the mice cortex a decrease in CCL2 concentrations, neuronal cell death, and microglial activation. Knock-out (KO) CCL2 mice fed with a vegetal control food already presented a decrease in cortical neuronal cell density in comparison with wild-type animals under similar diet conditions, suggesting that the presence of CCL2 is required for normal neuronal survival. Moreover, KO CCL2 mice showed a pronounced neuronal cell death in response to MeHg. Using in vitro experiments on pure rat cortical neurons in culture, we observed by blockade of the CCL2/CCR2 neurotransmission an increased neuronal cell death in response to MeHg neurotoxicity. Furthermore, we showed that sod genes are upregulated in brain of wild-type mice fed with MeHg in contrast to KO CCL2 mice and that CCL2 can blunt in vitro the decrease in glutathione levels induced by MeHg. These original findings demonstrate that CCL2 may act as a neuroprotective alarm system in brain deficits due to MeHg intoxicatio
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