321 research outputs found
Perturbations of isometries between Banach spaces
We prove a very general theorem concerning the estimation of the expression
for different kinds of maps
satisfying some general perurbated isometry condition. It can be seen as a
quantitative generalization of the classical Mazur-Ulam theorem. The estimates
improve the existing ones for bi-Lipschitz maps. As a consequence we also
obtain a very simple proof of the result of Gevirtz which answers the
Hyers-Ulam problem and we prove a non-linear generalization of the Banach-Stone
theorem which improves the results of Jarosz and more recent results of
Dutrieux and Kalton
Rigorous Multicomponent Reactive Separations Modelling : Complete Consideration of Reaction-Diffusion Phenomena
This paper gives the first step of the development of a rigorous multicomponent reactive separation model. Such a model is highly essential to further the optimization of acid gases removal plants (CO2 capture, gas treating, etc.) in terms of size and energy consumption, since chemical solvents are conventionally used.Firstly, two main modelling approaches are presented: the equilibrium-based and the rate-based approaches. Secondly, an extended rate-based model with rigorous modelling methodology for diffusion-reaction phenomena is proposed. The film theory and the generalized Maxwell-Stefan equations are used in order to characterize multicomponent interactions. The complete chain of chemical reactions is taken into account. The reactions can be kinetically controlled or at chemical equilibrium, and they are considered for both liquid film and liquid bulk. Thirdly, the method of numerical resolution is described. Coupling the generalized Maxwell-Stefan equations with chemical equilibrium equations leads to a highly non-linear Differential-Algebraic Equations system known as DAE index 3. The set of equations is discretized with finite-differences as its integration by Gear method is complex. The resulting algebraic system is resolved by the Newton- Raphson method. Finally, the present model and the associated methods of numerical resolution are validated for the example of esterification of methanol. This archetype non-electrolytic system permits an interesting analysis of reaction impact on mass transfer, especially near the phase interface. The numerical resolution of the model by Newton-Raphson method gives good results in terms of calculation time and convergence. The simulations show that the impact of reactions at chemical equilibrium and that of kinetically controlled reactions with high kinetics on mass transfer is relatively similar. Moreover, the Fick’s law is less adapted for multicomponent mixtures where some abnormalities such as counter-diffusion take place
I-70 Over SR 121 Bridge Slide
This presentation details the accelerated construction of the I-70 over Indiana SR 121 bridges and includes a brief history of the funding roles of INDOT and FHWA and the designer contract documents. The construction engineering methodology and step-by-step construction sequence will be detailed, with construction decisions for the slide, bridge demolition, bridge slide operations, and project completion
Les coopérations transfrontalières à l’épreuve de l’UE. Une comparaison Europe centrale-Turquie
Dans le cadre des politiques européennes de développement régional, les coopérations transfrontalières représentent un élément de toute première importance, pour trois raisons : elles renforcent les partenariats entre, d’une part, les acteurs centraux, régionaux et locaux, d’autre part, les acteurs publics privés et associatifs ; elles s’adossent à l’architecture décentralisée des Etats en assignant à chaque niveau d’intervention son propre rôle en matière de développement ; enfin, elles favorisent l’initiative locale. Elles deviennent ainsi les vecteurs de la « gouvernance à niveaux multiples » qu’entend promouvoir l’Union européenne (UE), en liant l’organisation de l’action publique, les coopérations entre acteurs et l’ancrage dans les territoires. Pour un Etat très centralisé comme la Turquie il s’agit d’un défi et d’une chance : défi, parce que la régionalisation concerne directement la structure unitaire de l’Etat. Chance, parce que l’UE n’oblige à aucune décentralisation forcée. Au contraire, elle laisse aux acteurs nationaux le soin d’aménager leur propre architecture territoriale en fonction de leur trajectoire historique et de la négociation entre centre et périphérie. Cette Etude le démontre en insistant sur deux aspects des transformations turques : la décentralisation n’est nullement un préalable à l’adhésion ; des coopérations différentiées existent aux frontières avec la Bulgarie et avec la Syrie, preuve de la dynamique d’européanisation des administrations turques.Cross-border cooperation in the EU policy of regional development is crucial for three reasons: it reinforces partnerships between, on the one hand, central, regional and local agents, and on the other hand, public, private, and associative actors; it rests on the decentralized structure of states, assigning to each level of intervention a unique role in the development process. Finally, it supports local initiative. Cross-border cooperation becomes a vehicle for the “multi-level governance” that the EU intends to promote, by linking organization of regionalized action, cooperation between actors, and solid territorial establishment. For Turkey the task represents a challenge and an opportunity. A challenge, because regionalization directly affects the unitary structure of the state. An opportunity, because the EU does not impose any model of decentralization. On the contrary, the EU gives national actors the chance to create their own public structures in function of their historical path and the negotiation between the centre and the periphery. This is what this study ultimately attempts to show, stressing two aspects of Turkish transformations: decentralization is not a precondition for membership and that different forms of cooperation exist at the borders with Bulgaria and Syria, as a proof of the Europeanization of the Turkish public administrations
Persistence of the immune response induced by BCG vaccination.
BACKGROUND: Although BCG vaccination is recommended in most countries of the world, little is known of the persistence of BCG-induced immune responses. As novel TB vaccines may be given to boost the immunity induced by neonatal BCG vaccination, evidence concerning the persistence of the BCG vaccine-induced response would help inform decisions about when such boosting would be most effective. METHODS: A randomised control study of UK adolescents was carried out to investigate persistence of BCG immune responses. Adolescents were tested for interferon-gamma (IFN-gamma) response to Mycobacterium tuberculosis purified protein derivative (M.tb PPD) in a whole blood assay before, 3 months, 12 months (n = 148) and 3 years (n = 19) after receiving teenage BCG vaccination or 14 years after receiving infant BCG vaccination (n = 16). RESULTS: A gradual reduction in magnitude of response was evident from 3 months to 1 year and from 1 year to 3 years following teenage vaccination, but responses 3 years after vaccination were still on average 6 times higher than before vaccination among vaccinees. Some individuals (11/86; 13%) failed to make a detectable antigen-specific response three months after vaccination, or lost the response after 1 (11/86; 13%) or 3 (3/19; 16%) years. IFN-gamma response to Ag85 was measured in a subgroup of adolescents and appeared to be better maintained with no decline from 3 to 12 months. A smaller group of adolescents were tested 14 years after receiving infant BCG vaccination and 13/16 (81%) made a detectable IFN-gamma response to M.tb PPD 14 years after infant vaccination as compared to 6/16 (38%) matched unvaccinated controls (p = 0.012); teenagers vaccinated in infancy were 19 times more likely to make an IFN-gamma response of > 500 pg/ml than unvaccinated teenagers. CONCLUSION: BCG vaccination in infancy and adolescence induces immunological memory to mycobacterial antigens that is still present and measurable for at least 14 years in the majority of vaccinees, although the magnitude of the peripheral blood response wanes from 3 months to 12 months and from 12 months to 3 years post vaccination. The data presented here suggest that because of such waning in the response there may be scope for boosting anti-tuberculous immunity in BCG vaccinated children anytime from 3 months post-vaccination. This supports the prime boost strategies being employed for some new TB vaccines currently under development
Engraftment Syndrome after Nonmyeloablative Allogeneic Hematopoietic Stem Cell Transplantation: Incidence and Effects on Survival
AbstractEngraftment syndrome (ES) encompasses a constellation of symptoms that occur during neutrophil recovery after both autologous and allogeneic hematopoietic stem cell transplantation (HCT). Although it is well characterized after conventional myeloablative procedures, limited data exist on this complication after nonmyeloablative allogeneic HCT. The clinical manifestations, incidence, and risk factors associated with ES were investigated in a consecutive series of patients undergoing cyclophosphamide/fludarabine-based nonmyeloablative allogeneic HCT from a related HLA-compatible donor. Fifteen (10%) of 149 patients (median age, 53 years; range, 27–66 years) developed ES; the onset of symptoms occurred at a median of 10 days (range, 3–14 days), and they consisted of fever (100%), cough (53%), diffuse pulmonary infiltrates (100%), rash (13%), and room air hypoxia (87%). ES was more likely to develop in patients who received empiric amphotericin formulations after transplant conditioning (Fisher exact test; P = .007). In a multivariate analysis, older patient age, female sex, and treatment with amphotericin were predictors for the development of ES. Intravenous methylprednisolone led to the rapid resolution of ES; however, transplant-related mortality was significantly higher (cumulative incidence, 49% versus 16%; P = .0005), and median survival was significantly shorter (168 versus 418 days; P = .005) in patients with ES compared with non-ES patients. In conclusion, ES occurs commonly after cyclophosphamide/fludarabine-based nonmyeloablative transplantation and responds rapidly to corticosteroid treatment, but it is associated with a higher risk of nonrelapse mortality and with shorter overall survival
A role for tumor necrosis factor-alpha in remodeling the splenic marginal zone during Leishmania donovani infection.
The development of secondary lymphoid organs is a highly regulated process, mediated by tumor necrosis factor (TNF) family cytokines. In contrast, the mechanisms controlling changes in lymphoid architecture that occur during infectious disease are poorly understood. Here we demonstrate that during infection with Leishmania donovani, the marginal zone of mice undergoes extensive remodeling, similar in extent to developmental abnormalities in mice lacking some TNF family cytokines. This process is selective, comprising a dramatic and rapid loss of marginal zone macrophages (MZMs). As a functional consequence, lymphocyte traffic into the white pulp is impaired during chronic leishmaniasis. Significantly, MZMs were preserved in L. donovani-infected B6.TNF-alpha(-/-) mice or mice that received anti-TNF-alpha antibodies, whereas studies in CD8(+) T-cell-deficient mice and in mice lacking functional CD95L, excluded a direct role for either cytotoxic T lymphocyte activity or CD95-mediated apoptosis in this process. Loss of MZMs was independent of parasite burden, yet could be partially prevented by chemotherapy, which in turn reduced endogenous TNF-alpha levels. This is the first report of an infectious agent causing selective and long-lasting changes to the marginal zone via TNF-alpha-mediated mechanisms, and illustrates that those cytokines involved in establishing lymphoid architecture during development, may also play a role in infection-induced lymphoid tissue remodeling
Mycobacterium tuberculosis PPD-induced immune biomarkers measurable in vitro following BCG vaccination of UK adolescents by multiplex bead array and intracellular cytokine staining
BACKGROUND: The vaccine efficacy reported following Mycobacterium bovis Bacillus Calmette Guerin (BCG) administration to UK adolescents is 77% and defining the cellular immune response in this group can inform us as to the nature of effective immunity against tuberculosis. The aim of this study was to identify which cytokines and lymphocyte populations characterise the peripheral blood cellular immune response following BCG vaccination. RESULTS: Diluted blood from before and after vaccination was stimulated with Mycobacterium tuberculosis purified protein derivative for 6 days, after which soluble biomarkers in supernatants were assayed by multiplex bead array. Ten out of twenty biomarkers measured were significantly increased (p < 0.0025) 1 month after BCG vaccination when compared to paired samples (n = 12) taken prior to vaccination (IFNgamma, TNFalpha, IL-1alpha, IL-2, IL-6, IL-10, IL-17, GM-CSF, MIP1alpha, IP-10). All of these remained detectable by multiplex bead array in samples taken 12 months after BCG vaccination of a partially overlapping adolescent group (n = 12). Intracellular cytokine staining after 24 hour Mycobacterium tuberculosis purified protein derivative stimulation of PBMC samples from the 12 month group revealed that IFNgamma expression was detectable in CD4 and CD8 T-cells and natural killer cells. Polyfunctional flow cytometry analysis demonstrated that cells expressing IFNgamma alone formed the majority in each subpopulation of cells. Only in CD4 T-cells and NK cells were there a notable proportion of responding cells of a different phenotype and these were single positive, TNFalpha producers. No significant expression of the cytokines IL-2, IL-17 or IL-10 was seen in any population of cells. CONCLUSIONS: The broad array of biomarker responses detected by multiplex bead array suggests that BCG vaccination is capable, in this setting, of inducing a complex immune phenotype. Although polyfunctional T-cells have been proposed to play a role in protective immunity, they were not present in vaccinated adolescents who, based on earlier epidemiological studies, should have developed protection against pulmonary tuberculosis. This may be due to the later sampling time point available for testing or on the kinetics of the assays used
Differences between naive and memory T cell phenotype in Malawian and UK adolescents: a role for Cytomegalovirus?
Background: Differences in degree of environmental exposure to antigens in early life have been hypothesized to lead to differences in immune status in individuals from different populations, which may have implications for immune responses in later years.Methods: Venous blood from HIV-negative adolescents and blood from the umbilical cords of babies, born to HIV-negative women, post-delivery was collected and analysed using flow cytometry. T cell phenotype was determined from peripheral blood lymphocytes and cytomegalovirus (CMV) seropositivity was assessed by ELISA in adolescents.Results: HIV-negative Malawian adolescents were shown to have a lower percentage of naive T cells (CD45RO-CD62L(hi)CD11a(lo)), a higher proportion of memory T cells and a higher percentage of CD28(-) memory (CD28(-)CD45RO(+)) T cells compared to age-matched UK adolescents. Malawian adolescents also had a lower percentage of central memory (CD45RA(-)CCR7(+)) T cells and a higher percentage of stable memory (CD45RA(+)CCR7(-)) T cells than UK adolescents. All of the adolescents tested in Malawi were seropositive for CMV (59/59), compared to 21/58 (36%) of UK adolescents. CMV seropositivity in the UK was associated with a reduced percentage of naive T cells and an increased percentage of CD28- memory T cells in the periphery. No differences in the proportions of naive and memory T cell populations were observed in cord blood samples from the two sites.Conclusion: It is likely that these differences between Malawian and UK adolescents reflect a greater natural exposure to various infections, including CMV, in the African environment and may imply differences in the ability of these populations to induce and maintain immunological memory to vaccines and natural infections
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