A first order phase transition with non-constant density

AbstractWe introduce a new model for first order phase transitions accounting for non-constant densities of the phases during the process. The resulting initial and boundary value problem for a PDE system is recovered by thermodynamical principles. The resulting system presents some singularities and strong nonlinearities accounting for internal constraints, ensuring in particular the positivity of the pressure and the temperature. Physical consistency for the order parameter comes from a maximum principle argument. Existence of a weak solution is proved by a regularization-passage to the limit procedure

Thermoelectric energy recovery at ionic-liquid/electrode interface

A Thermally Chargeable Capacitor containing a binary solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile is electrically charged by applying a tempera- ture gradient to two ideally polarisable electrodes. The corresponding thermoelectric coefficient is -1.7 mV/K for platinum foil electrodes and -0.3 mV/K for nanoporous carbon electrodes. Stored electrical energy is extracted by discharging the capacitor through a resistor. The measured capacitance of the electrode/ionic- liquid interface is 5 micro $\mu$F for each platinum electrode while it becomes four orders of magnitude larger $\approx 36$ mF for a single nanoporous carbon electrode. Reproducibility of the effect through repeated charging-discharging cycles under a steady-state temperature gradient demonstrates the robustness of the electrical charging pro- cess at the liquid/electrode interface. The acceleration of the charging by convective flows is also observed. This offers the possibility to convert waste-heat into electric energy without exchanging electrons between ions and electrodes, in contrast to what occurs in most thermogalvanic cells.Comment: 8 pages, 11 figure

Démarches de développement: la participation des habitants

Cet article vise à expliciter la conception et l’organisation des processus de participation des habitants que nous avons expérimenté dans le cadre de différentes opérations de réhabilitation ou de réaménagement urbain de quartiers d’habitat social. La maîtrise d’ouvrage de ces opérations était assurée par des organismes de logement social ou des collectivités locales. Après avoir précisé les différentes formes de participation que l’on peut mettre en oeuvre, nous présentons les principes qui doivent sous-tendre selon nous la mise en place des processus de participation. Nous développons ensuite la conception de ces processus qui nous paraît la plus pertinente et la plus efficace, et à l’issue de cet exposé méthodologique nous illustrons nos propos par un exemple concret de processus de participation que nous avons contribué à mettre en oeuvre à la demande de l’OPAC de Paris, dans le cadre d’une opération de réaménagement de l’espace urbain d’un quartier de 700 logements.FCT - Fundação para a Ciência e a TecnologiaMinistério da CulturaInstituto Português do Livro e das Biblioteca

Pyruvate dehydrogenase fuels a critical citrate pool that is essential for Th17 cell effector functions

Pyruvate dehydrogenase (PDH) is the central enzyme connecting glycolysis and the tricarboxylic acid (TCA) cycle. The importance of PDH function in T helper 17 (Th17) cells still remains to be studied. Here, we show that PDH is essential for the generation of a glucose-derived citrate pool needed for Th17 cell proliferation, survival, and effector function. In vivo, mice harboring a T cell-specific deletion of PDH are less susceptible to developing experimental autoimmune encephalomyelitis. Mechanistically, the absence of PDH in Th17 cells increases glutaminolysis, glycolysis, and lipid uptake in a mammalian target of rapamycin (mTOR)-dependent manner. However, cellular citrate remains critically low in mutant Th17 cells, which interferes with oxidative phosphorylation (OXPHOS), lipid synthesis, and histone acetylation, crucial for transcription of Th17 signature genes. Increasing cellular citrate in PDH-deficient Th17 cells restores their metabolism and function, identifying a metabolic feedback loop within the central carbon metabolism that may offer possibilities for therapeutically targeting Th17 cell-driven autoimmunity

Timing of initiation of oral anticoagulants in patients with acute ischemic stroke and atrial fibrillation comparing posterior and anterior circulation strokes

Background: The aim of this study in patients with acute posterior ischemic stroke (PS) and atrial fibrillation (AF) were to evaluate the risks of recurrent ischemic event and severe bleeding and these risks in relation with oral anticoagulant therapy (OAT) and its timing. Methods: Patients with PS were prospectively included; the outcome events of these patients were compared with those of patients with anterior stroke (AS) which were taken from previous registries. The primary outcome was the composite of: stroke recurrence, TIA, symptomatic systemic embolism, symptomatic cerebral bleeding and major extracranial bleeding occurring within 90 days from acute stroke. Results: A total of 2,470 patients were available for the analysis: 473 (19.1%) with PS and 1,997 (80.9%) AS. Over 90 days, 213 (8.6%) primary outcome events were recorded: 175 (8.7%) in patients with AS and 38 (8.0%) in those with PS. In patients who initiated OAT within 2 days, the primary outcome occurred in 5 out of 95 patients (5.3%) with PS compared to 21 out of 373 patients (4.3%) with AS (OR 1.07; 95% CI 0.39-2.94). In patients who initiated OAT between days 3 and 7, the primary outcome occurred in 3 out of 103 patients (2.9%) with PS compared to 26 out of 490 patients (5.3%) with AS (OR 0.54; 95% CI 0.16-1.80). Conclusions: Patients with posterior or anterior stroke and AF appear to have similar risks of ischemic or hemorrhagic events at 90 days with no difference concerning the timing of initiation of OAT

The risk of stroke recurrence in patients with atrial fibrillation and reduced ejection fraction

Abstract Background: Atrial fibrillation (AF) and congestive heart failure often coexist due to their shared risk factors leading to potential worse outcome, particularly cerebrovascular events. The aims of this study were to calculate the rates of ischemic and severe bleeding events in ischemic stroke patients having both AF and reduced ejection fraction (rEF) (⩽40%), compared to ischemic stroke patients with AF but without rEF. Methods: We performed a retrospective analysis that drew data from prospective studies. The primary outcome was the composite of either ischemic (stroke or systemic embolism), or hemorrhagic events (symptomatic intracranial bleeding and severe extracranial bleeding). Results: The cohort for this analysis comprised 3477 patients with ischemic stroke and AF, of which, 643 (18.3%) had also rEF. After a mean follow-up of 7.5 ± 9.1 months, 375 (10.8%) patients had 382 recorded outcome events, for an annual rate of 18.0%. While the number of primary outcome events in patients with rEF was 86 (13.4%), compared to 289 (10.2%) for the patients without rEF; on multivariable analysis rEF was not associated with the primary outcome (OR 1.25; 95% CI 0.84–1.88). At the end of follow-up, 321 (49.9%) patients with rEF were deceased or disabled (mRS ⩾3), compared with 1145 (40.4%) of those without rEF; on multivariable analysis, rEF was correlated with mortality or disability (OR 1.35; 95% CI 1.03–1.77). Conclusions: In patients with ischemic stroke and AF, the presence of rEF was not associated with the composite outcome of ischemic or hemorrhagic events over short-term follow-up but was associated with increased mortality or disability

Les risques de dérive dans la transformation des grands ensembles : Analyse d'une vingtaine de projets de renouvellement urbain

When Transforming Large Social Housing Estates Risks Going Wrong : An Analysis of Some Twenty Urban Regeneration Projects Views differ as to whether urban regeneration is a matter of heightening the existing urban character of large social housing estates, of seeking to improve them patiently over time or, yet again, of simply demolishing them. The more radical solutions meet with unexpected results, especially when the issues of day-to-day maintenance and the inhabitants' own views are not sufficiently taken into account. A practical sociology attentive to the ways in which social housing estates vary in respect of history and site tends to call into question the most one-dimensional large-scale projects.Accroître l'urbanité des grands ensembles, les démolir tout simplement ou chercher à les améliorer patiemment, les conceptions du renouvellement urbain divergent. Les solutions les plus radicales rencontrent des effets imprévus, surtout lorsque les questions d'entretien quotidien et d'opinion des habitants sont sous-estimées. Une sociologie pratique attentive à la diversité des histoires et des lieux de l'habitat social tend à remettre en question les grands projets les plus unidimensionnels.Bonetti Michel. Les risques de dérive dans la transformation des grands ensembles : Analyse d'une vingtaine de projets de renouvellement urbain. In: Les Annales de la recherche urbaine, N°97, 2004. Renouvellements urbains. pp. 34-42

Les réseaux de communication et la recomposition de l'espace urbain

L’objet de cette communication est de dégager différents processus par lesquels les réseaux et les services de communication peuvent infléchir le développement urbain et contribuer à une recomposition de l’espace. Après avoir rappelé que les grands urbanistes du 19e siècle (Haussmann à Paris, Cerda à Barcelone, Wagner à Vienne) ont repensé l’organisation urbaine en fonction du développement technologique nous essaierons de montrer comment les réseaux de communication s’insèrent dans des espaces urbains pré-structurés et peuvent modifier leur organisation interne et l’utilisation économique et sociale de l’espace. L’influence des réseaux de communications sur le développement urbain dépend donc des modes de structuration de l’espace, des dynamiques urbaines mais aussi des stratégies des acteurs qui orientent ce développement (industriels de la communication, responsables politiques, acteurs économiques, etc ...). Ces stratégies peuvent viser l’extension des frontières, la valorisation différentielle des espaces, l’articulation d’espaces disjoints, la concentration des services dans certaines zones, etc ... L’influence des réseaux de communication sur l’espace est de ce fait multiforme et on ne peut conclure mécaniquement comme le fait Virilio (Cf. L’espace critique) à une dissolution des formes urbaines. Cette problématique s’appuiera sur les évolutions qui émergent dans plusieurs villes françaises qui développement des stratégies différentes.Bonetti Michel. Les réseaux de communication et la recomposition de l'espace urbain. In: NETCOM : Réseaux, communication et territoires / Networks and Communication Studies, vol. 4 n°2, juin 1990. pp. 336-358