47,776 research outputs found
Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction
No full textWe examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the representative XMM-Newton cluster structure survey (REXCESS), a sample in the temperature range 2-9 keV selected in X-ray luminosity only, with no bias toward any particular morphological type. The entropy profiles are robustly measured at least out to R1000 in all systems and out to R500 in thirteen systems. Compared to theoretical expectations from non-radiative cosmological simulations, the observed distributions show a radial and mass-dependent excess entropy, such that the excess is greater and extends to larger radii in lower mass systems. At R500, the mass dependence and entropy excess are both negligible within the large observational and theoretical uncertainties. Mirroring this behaviour, the scaling of gas entropy is shallower than self-similar in the inner regions, but steepens with radius, becoming consistent with self-similar at R500. There is a large dispersion in scaled entropy in the inner regions, apparently linked to the presence of cool cores and dynamical activity; at larger radii the dispersion decreases by approximately a factor of two to 30 per cent, and the dichotomy between subsamples disappears. There are two peaks in the distribution of both inner slope and, after parameterising the profiles with a power law plus constant model, in central entropy K0. However, we are unable to distinguish between a bimodal or a left-skewed distribution of K0 with the present data. The distribution of outer slopes is unimodal with a median value of 0.98, and there is a clear correlation of outer slope with temperature. Renormalising the dimensionless entropy profiles by the gas mass fraction profile fgas (<R), leads to a remarkable reduction in the scatter, implying that gas mass fraction variations with radius and mass are the cause of the observed entropy structural and scaling properties. The results are consistent with the picture of a cluster population in which entropy modification is centrally concentrated and extends to larger radii at lower mass, leading to both a radial and a mass-dependence in the gas mass fraction, but which is increasingly self-similar at large radius. The observed normalisation, however, would suggest entropy modification at least up to R1000, and even beyond, in all but the most massive systems. We discuss a tentative scenario to explain the observed behaviour of the entropy and gas mass fraction in the REXCESS sample, in which a combination of extra heating and merger mixing maintains an elevated central entropy level in the majority of the population, and a smaller fraction of systems is able to develop a cool core. <br/
Scratch resistant tough nanocomposite epoxy coatings based on hyperbranched polyesters
No full textAdvanced multifunctional coatings were prepared by UV curing of epoxy based formulations containing hyperbranched polymers (HBP) and an epoxy functionalized alkoxysilane additive. The addition of HBP to the UV curable epoxy resin induced an important flexibilization of the glassy epoxy network with an increase in toughness of the cured polymeric coatings. Adding the functionalized alkoxysilane into the UV curable formulations, as inorganic precursor of silica phase, an improvement on surface hardness was obtained without strongly affecting the flexibilization and the toughness achieved by the addition of the HBP additive. The increase on surface hardness was accompanied with an increase in scratch resistance and modulus. Advanced scratch resistant and tough nanocomposite epoxy coatings were obtained by properly selecting the components of the formulation
Testing the Limits of AGN Feedback and the Onset of Thermal Instability in the Most Rapidly Star-forming Brightest Cluster Galaxies
No full textWe present new, deep, narrow- and broadband Hubble Space Telescope observations of seven of the most star-forming brightest cluster galaxies (BCGs). Continuum-subtracted [OII] maps reveal the detailed, complex structure of warm (T ~ 104 K) ionized gas filaments in these BCGs, allowing us to measure spatially resolved star formation rates (SFRs) of ~60-600 M ⊙yr-1. We compare the SFRs in these systems and others from the literature to their intracluster medium cooling rates ( ), measured from archival Chandra X-ray data, finding a best-fit relation of + (-3.22 ± 0.38) with an intrinsic scatter of 0.39 ± 0.09 dex. This steeper-than-unity slope implies an increasingly efficient conversion of hot (T ~ 107 K) gas into young stars with increasing , or conversely a gradual decrease in the effectiveness of AGN feedback in the strongest cool cores. We also seek to understand the physical extent of these multiphase filaments that we observe in cluster cores. We show, for the first time, that the average extent of the multiphase gas is always smaller than the radii at which the cooling time reaches 1 Gyr, the t cool/t ff profile flattens, and that X-ray cavities are observed. This implies a close connection between the multiphase filaments, the thermodynamics of the cooling core, and the dynamics of X-ray bubbles. Interestingly, we find a one-to-one correlation between the average extent of cool multiphase filaments and the radius at which the cooling time reaches 0.5 Gyr, which may be indicative of a universal condensation timescale in cluster core
G. M. Hopkins
No full text[sound recording] / Brendan O'Grady. G. B. Shaw by Fran Frazer.; 1 sound cassette (60 minutes); Broadcast on CFCY Radio, Charlottetown, March 07 & 11, 1974.; G. B. ShawSource type: Electronic(1
Erratum to: Effect of moderate red wine intake on cardiac prognosis after recent acute myocardial infarction of subjects with Type 2 diabetes mellitus (Diabetic Medicine, (2006), 23, 9, (974-981), 10.1111/j.1464-5491.2006.01886.x)
No full textIn an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola.In an article by Marfella et al, the author name C. Saron is incorrect and should be listed as C. Sardu. Therefore the correct author list is: R. Marfella, F. Cacciapuoti, M. Siniscalchi, F. C. Sasso, F. Marchese, F. Cinone, E. Musacchio, M. A. Marfella, L. Ruggiero, G. Chiorazzo, D. Liberti, G. Chiorazzo, G. F. Nicoletti, C. Sardu, F. D'Andrea, C. Ammendola, M. Verza and L. Coppola
The M&G Drive
No full textabstract: The M&G Drive is a proposed venture project lead by Barrett seniors, Elijah Smith and Jenna Fitzgerald. This project aims to educate Arizona State University (ASU) students on the issues of food insecurity around the Phoenix valley and facilitate their involvement in helping alleviate this pressing social matter. Scientific research has shown significant inverse relationships between food insecurity and the following: mental and physical health, social skills, and academic achievement. As the largest public university in the nation, Arizona State holds a self-ascribed responsibility for the health of its communities. In order to address this issue on behalf of Arizona State and from the standpoint of college students, this proposed venture will encourage the ASU student population to reallocate their unused M&G Dollars (ASU’s on-campus currency) to go toward this cause. Rather than being absorbed back by the university system, unused M&G Dollars can instead be used to purchase non-perishables that will then be donated to the local Phoenix community in order to help fight against food insecurity
Lah–Ribarič type inequalities for (h, g; m)-convex functions
No full textRecently introduced new class of (h, g; m)-convex functions unifies a certain range of convexity, thus allowing the generalizations of know results. In this paper we prove Lah–Ribarič type inequalities for (h, g; m)-convex functions from which we obtain inequalities of Hermite–Hadamard, Fejér, Giaccardi, Popoviciu and Petrović. © 2021, The Author(s) under exclusive licence to The Royal Academy of Sciences, Madrid
Representative Bureaucracy and the Willingness to Coproduce: An Experimental Study
No full textRelying on the theory of representative bureaucracy—specifically, the notion of symbolic representation—this article examines whether varying the number of female public officials overseeing a local recycling program influences citizens’ (especially women's) willingness to cooperate with the government by recycling, thus coproducing important policy outcomes. Using a survey experiment in which the first names of public officials are manipulated, the authors find a clear pattern of increasing willingness on the part of women to coproduce when female names are more represented in the agency responsible for recycling, particularly with respect to the more difficult task of composting food waste. Overall, men in the experiment were less willing to coproduce across all measures and less responsive to the gender balance of names. These findings have important implications for the theory of representative bureaucracy and for efforts to promote the coproduction of public services.This is the peer reviewed version of the following article: Riccucci, Norma M., Van Ryzin, Gregg G. & Li, Huafang. (2015). Representative Bureaucracy and the Willingness to Coproduce: An Experimental Study. Public Administration Review, which has been published in final form at http://dx.doi.org/10.1111/puar.12401. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Peer reviewe
Do True Metabolic Pathway Models Exist?
No full textMetabolic systems are among of the oldest applications of mathematical modeling. Spanning a time period of over one hundred years, the repertoire of options for structuring metabolic models and for formulating reactions has been growing constantly, and yet, it is still unclear whether or to what degree some models are better than others and how the modeler is to choose among them. This situation begs the question whether there are representations of metabolic processes that are true over reasonably wide ranges, yet mathematically tractable. A glimpse into such representations is provided by Dynamic Flux Estimation which, under ideal conditions, reveals the actual shapes of functions representing metabolic processes, although not their mathematical formats. While intriguing, DFE is only directly applicable if a pathway system contains as many dependent variables as fluxes. Because most actual systems contain more fluxes than metabolite pools, this requirement is seldom satisfied. Some auxiliary methods have been proposed to alleviate this issue, but they were quite ad hoc. Here I demonstrate a generic strategy that renders DFE applicable to moderately underdetermined pathway systems. A second challenge with DFE is the need to identify explicit functional formats that have shapes as close as possible to those inferred. Clearly, even if this inference is feasible, the result is necessarily biased. As an alternative, I demonstrate that good time series data allow us to circumvent this step and to develop nonlinear dynamic models in an entirely nonparametric fashion. The resulting nonparametric models offer a surprisingly wide range of analytic tools, including stability and sensitivity analyses. I will finish with some comments on dynamical model reduction, using power-law models.
Goel, G., I-C. Chou, and E.O. Voit: System estimation from metabolic time series data. Bioinformatics 24, 2505-2511, 2008.
Dolatshahi, S., and E.O. Voit: Identification of metabolic pathway systems. Frontiers in Genetics 7:6, 2016.
Faraji, M. and E.O. Voit: Nonparametric dynamic modeling. Math. Biosc. 287, 130-146, 2017.
Faraji, M. and E.O. Voit: Stepwise inference of likely dynamic flux distributions from metabolic time series data. Bioinformatics, 33 (14): 2165-2172; 2017.
Voit, E.O.: The best models of metabolism. WIREs Systems Biology and Medicine. (in press)Non UBCUnreviewedAuthor affiliation: Georgia Institute TechnologyFacult
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