18,683 research outputs found

    Suppression of allergic airway inflammation by helminth-induced regulatory T cells

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    Allergic diseases mediated by T helper type (Th) 2 cell immune responses are rising dramatically in most developed countries. Exaggerated Th2 cell reactivity could result, for example, from diminished exposure to Th1 cell–inducing microbial infections. Epidemiological studies, however, indicate that Th2 cell–stimulating helminth parasites may also counteract allergies, possibly by generating regulatory T cells which suppress both Th1 and Th2 arms of immunity. We therefore tested the ability of the Th2 cell–inducing gastrointestinal nematode Heligmosomoides polygyrus to influence experimentally induced airway allergy to ovalbumin and the house dust mite allergen Der p 1. Inflammatory cell infiltrates in the lung were suppressed in infected mice compared with uninfected controls. Suppression was reversed in mice treated with antibodies to CD25. Most notably, suppression was transferable with mesenteric lymph node cells (MLNC) from infected animals to uninfected sensitized mice, demonstrating that the effector phase was targeted. MLNC from infected animals contained elevated numbers of CD4(+)CD25(+)Foxp3(+) T cells, higher TGF-β expression, and produced strong interleukin (IL)-10 responses to parasite antigen. However, MLNC from IL-10–deficient animals transferred suppression to sensitized hosts, indicating that IL-10 is not the primary modulator of the allergic response. Suppression was associated with CD4(+) T cells from MLNC, with the CD4(+)CD25(+) marker defining the most active population. These data support the contention that helminth infections elicit a regulatory T cell population able to down-regulate allergen induced lung pathology in vivo

    The Relationship between Innovation Influence and Customer Loyalty: An Empirical Study of an Experience Economy Industry

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    2014 dissertation for MSc in International Business Management. Selected by academic staff as a good example of a masters level dissertation. Good customer experience is a driver to increased customer satisfaction, leading to customer loyalty. This is prominent in the context of experience economy industries, an industry where the main purchase is an experience. Previous conflicting theory depicts innovation as a positive influencer and non-influencer of customer satisfaction. To add value, a new research is proposed by incorporating two new elements. 1 - Innovation in the forms of customer related, innovation a customer directly experiences, and cocustomer related, innovation a customer directly experiences and aides in the development process. 2 - The research uses two separate kinds of customers, loyal and non-loyal. This sets the stage for the research question: what is the relationship between innovation influence and different levels of customer loyalty? The hypotheses will test the correlation between the influences of the two innovation forms amongst loyal and non-loyal customers. The chosen industry is U.S. amusement parks and the sample population will be its customers. The research method will incorporate a normative questionnaire regarding participant opinions and behaviours towards certain elements. The data concluded that innovation plays little to no positive influence on customer opinion or behaviour. Conversely, the scientific testing discovered a significant positive correlation between the influences of the two innovation forms amongst loyal customers. Therefore, if your loyal customers are positively influenced by new products or services, they will be positively influenced by co-creating new products or services. Recommendations for a different industry context and a more varied description of customer loyalty are proposed for further research

    Surveying Gender Bias at One Midwestern Law School

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    Highly selective hydrogenation of furfural over supported Pt nanoparticles under mild conditions

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    The selective liquid phase hydrogenation of furfural to furfuryl alcohol over Pt nanoparticles supported on SiO₂, ZnO, γ-Al2O₃, CeO₂ is reported under extremely mild conditions. Ambient hydrogen pressure, and temperatures as low as 50 °C are shown sufficient to drive furfural hydrogenation with high conversion and >99% selectivity to furfuryl alcohol. Strong support and solvent dependencies are observed, with methanol and n-butanol proving excellent solvents for promoting high furfuryl alcohol yields over uniformly dispersed 4 nm Pt nanoparticles over MgO, CeO₂ and γ-Al₂O₃. In contrast, non-polar solvents conferred poor furfural conversion, while ethanol favored acetal by-product formation. Furfural selective hydrogenation can be tuned through controlling the oxide support, reaction solvent and temperature

    The Starburst in the Central Kiloparsec of Markarian 231

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    We present VLBA observations at 0.33 and 0.61 GHz, and VLA observations between 5 and 22 GHz, of subkiloparsec scale radio emission from Mrk 231. In addition to jet components clearly associated with the AGN, we also find a smooth extended component of size 100 - 1000 pc most probably related to the purported massive star forming disk in Mrk 231. The diffuse radio emission from the disk is found to have a steep spectrum at high frequencies, characteristic of optically thin synchrotron emission. The required relativistic particle density in the disk can be produced by a star formation rate of 220 Msolar/yr in the central kiloparsec. At low frequencies the disk is absorbed, most likely by ionized gas with an emission measure of 8 x 10^5 pc cm-6. We have also identified 4 candidate radio supernovae that, if confirmed, represent direct evidence for ongoing star formation in the central kiloparsec.Comment: in press at ApJ for v. 519 July 1999, 14 page LaTeX document includes 6 postscript figure

    Extracellular chloride is required for efficient activation of secondary signalling pathways during platelet aggregation

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    Anion channels perform a diverse range of functions and have been implicated in ATP release, volume regulation and phosphatidylserine exposure. Platelets have been shown to express several anion channels however their function is incompletely understood. Due to a paucity of specific pharmacological blockers, we investigated the global effect of extracellular chloride substitution on platelet activation using aggregometry and flow cytometry. In the absence of extracellular chloride we observed a modest effect on the maximum aggregation response to thrombin or collagen-related peptide. Although the rate of aggregation was substantially reduced in a manner that was dependent on the extracellular chloride concentration, aggregation in the absence of chloride was noticeably biphasic, indicative of impaired secondary signalling. This was further investigated by targeting secondary agonists with aspirin and apyrase or by blockade of the ADP receptor P2Y12. Under these conditions, the rates of aggregation were comparable to those recorded in the absence of extracellular chloride. Finally, we assessed platelet granule release by flow cytometry and report a chloride-dependent element of alpha, but not dense, granule secretion. Taken together these data support a role for anion channels in the efficient induction of platelet activation, likely via enhancement of secondary signalling pathways

    Do Jet-Driven Shocks ionize the Narrow Line Regions of Seyfert Galaxies?

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    We consider a model in which the narrow line regions (NLRs) of Seyfert galaxies are photoionized ``in situ'' by fast (300 -- 1,000 km/s), radiative shock waves driven into the interstellar medium of the galaxy by radio jets from the active nucleus. Such shocks are powerful sources of soft X-rays. We compute the expected ratio of the count rates in the ROSAT PSPC and Einstein IPC detectors to the [OIII] \lambda 5007 flux as a function of shock velocity, and compare these ratios with observations of type 2 Seyferts. If most of the observed soft X-ray emission from these galaxies originates in the NLR and the absorbing hydrogen column is similar to that inferred from the reddening of the NLR, a photoionizing shock model with shock velocity ≃\simeq 400 -- 500 km/s is compatible with the observed ratios. High angular resolution observations with AXAF are needed to isolate the X-ray emission of the NLR and measure its absorbing column, thus providing a more conclusive test. We also calculate the expected coronal iron line emission from the shocks. For most Seyfert 2s, the [Fe X] \lambda 6374/H \beta$ ratio is a factor of 2 -- 14 lower than the predictions of 300 -- 500 km/s shock models, suggesting that less hot gas is present than required by these models.Comment: Astrophys J. Letters 1999 March 10 issue, Vol. 51
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