196,572 research outputs found
On the intrinsic AGN emission in the far-infrared/sub-mm
No full textFar-infrared (far-IR)/sub-mm emission linked to AGN-heated dust has been a topic of contention for many years. Results have been diverse and various views have been presented. The empirical AGN SED derived by Symeonidis et al. (2016, hereafter S16) has more far-IR/sub-mm emission than other SEDs in the literature, and thus it is contested by other works which argue that its luminosity in that part of the spectrum is overestimated. Here, I investigate this topic and the concerns raised over the S16 AGN SED. I also examine the differences between the S16 AGN SED and other commonly used empirical AGN SEDs. My findings show that the reasons proposed by other works as to why the S16 AGN SED is not a reasonable representation of AGN emission in the far-IR/sub-mm, do not hold
Turbulent drag reduction by traveling waves of spanwise forcing
No full textSeveral techniques based on spanwise focing were introduced in the last decade \cite{du-symeonidis-karniadakis-2002, quadrio-ricco-viotti-2009} in the form of traveling waves of spanwise forcing as generalization of the spanwise-wall oscillation technique to reduce skin-friction drag in a turbulent channel flow. Here we examine all their variants (including one that has never been considered before), by addressing the type of forcing (wall movement versus body force) as well as the traveling direction (streamwise versus spanwise) of the waves. We carry out a DNS-based study within an unified framework, to compare their capability to reduce skin-friction drag and, more importantly, net energy savings. The present results confirm the potential for drag reductions for every considered forcing. The best-performing spanwise traveling wave, in terms of either drag reduction or net energy saving, is found to be the one with infinite wavelength, i.e. still the spanwise wall oscillation. The streamwise-traveling waves consistently offer the best performance, especially in terms of net savings. The conditions under which body-force based control can be meaningfully compared to wall based control are discussed
Price Competition, Innovation and Profitability: Theory and UK Evidence
No full textThis paper examines the effect of price competition on innovation, market structure and profitability in R&D-intensive industries. The theoretical predictions are tested using UK data on the evolution of competition, concentration, innovation counts and profitability over 1952-1977. The econometric results suggest that the introduction of restrictive practices legislation in the UK had no significant effect on the number of innovations commercialised in previously cartelised R&D-intensive manufacturing industries, while it caused a significant rise in concentration in these industries. In the short run profitability decreased, but in the long run it was restored through the rise in concentration.
Photoionisation modelling of the X-ray emission line regions within the Seyfert 2 AGN NGC 1068
No full textAIMS: We investigate the photoionised X-ray emission line regions (ELRs) within the Seyfert 2 galaxy NGC 1068 to determine if there are any characteristic changes between observations taken 14 years apart. METHODS: We compared XMM-Newton observations collected in 2000 and 2014, simultaneously fitting the reflection grating spectrometer and EPIC-pn spectra of each epoch, for the first time, with the photoionisation model, PION, in SPEX. RESULTS We find that four PION components are required to fit the majority of the emission lines in the spectra of NGC 1068, with logζ = 1-4, log N_{H} > 26 m^{-2}, and v_{out} = -100 to -600 km s^{-1} for both epochs. Comparing the ionisation state of the components shows almost no difference between the two epochs, while there is an increase in the total equivalent column density. To estimate the locations of these plasma regions from the central black hole, we compare distance methods, excluding the variability arguments as there is no spectral change between observations. Although the methods are unable to constrain the distances for each plasma component, the locations are consistent with the narrow line region, with the possibility of the higher ionised component being part of the broad line region; we cannot conclude this for certain, but the photoionisation modelling does suggest this is possible. In addition, we find evidence for emission from collisionally ionised plasma, while previous analysis had suggested that collisional plasma emission was unlikely. However, although PION is unable to account for the Fe » XVII emission lines at 15 and 17 Å, we do not rule out that photoexcitation is a valid processes to produce these lines as well. CONCLUSIONS: NGC 1068 has not changed, both in terms of the observed spectra or from our modelling, within the 14 year time period between observations. This suggests that the ELRs are fairly static relative to the 14 year time frame between observations, or there is no dramatic change in the spectral energy distribution, resulting from a lack of black hole variability
Comparing Cournot and Bertrand Equilibria in a Differentiated Duopoly with Product R&D
No full textThis paper compares Bertrand and Cournot equilibria in a differentiated duopoly with substitute goods and product R&D. I find that R&D expenditure, prices and firms� net profits are always higher under quantity competition than under price competition. Furthermore, output, consumer surplus and total welfare are higher in the Bertrand equilibrium than in the Cournot equilibrium if either R&D spillovers are weak or products are sufficiently differentiated. If R&D spillovers are strong and products are not too differentiated, then output, consumer surplus and total welfare are lower in the Bertrand case than in the Cournot case. Thus a key finding of the paper is that there are circumstances where quantity competition can be more beneficial than price competition both for consumers and for firms.
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
The link between SCUBA and Spitzer: cold galaxies at z≲ 1
No full textWe show that the far-IR properties of distant Luminous and UltraLuminous InfraRed Galaxies (LIRGs and ULIRGs, respectively) are on average divergent from analogous sources in the local Universe. Our analysis is based on Spitzer Multiband Imaging Photometer (MIPS) and Infrared Array Camera (IRAC) data of LIR > 1010 L⊙, 70 μm selected objects in the 0.1 1 SubMillimetre Galaxies (SMGs) discovered in blank-field submillimetre surveys. The Herschel Space Observatory is well placed to fully characterize the nature of these objects, as its coverage extends over a major part of the far-IR/sub-mm SED for a wide redshift range
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