Large-scale structures from infrared surveys

To use the AKARI All-Sky Survey Point Source Catalogue as a validation sample for future missions such as Planck and to study large-scale structure, we first investigate the AKARI point source detection limit at 90 μm and the nature of bright spurious sources. Due to the degradation of the sensitivity of the AKARI All-Sky Survey and formidable difficulties in filtering out excessive noise, we return to the IRAS Faint Source Catalog to construct a redshift catalogue of over 60,000 galaxies selected at 60 μm, the Imperial IRAS-FSC Redshift Catalogue (IIFSCz). Around 50% of the sources in the IIFSCz have spectroscopic redshifts and a further 20% have photometric redshifts. The luminosity and selection functions are obtained for the IIFSCz flux-limited at 0.36 Jy at 60 μm. The dependence of galaxy clustering on spectral type and luminosity is studied using correlation statistics. A possible detection of the baryon acoustic oscillations in the power spectrum of the flux-limited sample of the IIFSCz is discussed. Finally, we present future research directions which include the FIR-radio correlation, ultraluminous and hyperluminous infrared galaxies, galaxy bias in the SWIRE Photometric Redshift Catalogue and convergence of the cosmological dipole

Conditions implying regularity of the three dimensional Navier-Stokes equation

We obtain logarithmic improvements for conditions for regularity of the Navier-Stokes equation, similar to those of Prodi-Serrin or Beale-Kato-Majda. Some of the proofs make use of a stochastic approach involving Feynman-Kac like inequalities. As part of the our methods, we give a different approach to a priori estimates of Foias, Guillope and Temam.Comment: Also available at http://www.math.missouri.edu/~stephen/preprints/ (Changes: this is a substantial rewrite of the previous version.

On the blow up criterion for the 2-D compressible Navier-Stokes equations

summary:Motivated by [10], we prove that the upper bound of the density function $\rho$ controls the finite time blow up of the classical solutions to the 2-D compressible isentropic Navier-Stokes equations. This result generalizes the corresponding result in [3] concerning the regularities to the weak solutions of the 2-D compressible Navier-Stokes equations in the periodic domain

Novel Forms of Rewriting Aristophanes’ Comedies: Comic Book Adaptations and Their Translations

Prikaz knjige: Asimakoulas, Dimitris. Rewriting Humour in Comic Books: Cultural Transfer and Translation of Aristophanic Adaptations. Palgrave Macmillan, 2019, pp. 189

Principal Component Analysis and Radiative Transfer modelling of Spitzer IRS Spectra of Ultra Luminous Infrared Galaxies

The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterise the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilise the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. We further investigate the principal components (PCs) of ULIRGs derived in Wang et al.(2011). We quantitatively show that five PCs is optimal for describing the IRS spectra. These five components (PC1-PC5) and the mean spectrum provide a template basis set that reproduces spectra of all z<0.35 ULIRGs within the noise. For comparison, the spectra are also modelled with a combination of radiative transfer models of both starbursts and the dusty torus surrounding active galactic nuclei. The five PCs typically provide better fits than the models. We argue that the radiative transfer models require a colder dust component and have difficulty in modelling strong PAH features. Aided by the models we also interpret the physical processes that the principal components represent. The third principal component is shown to indicate the nature of the dominant power source, while PC1 is related to the inclination of the AGN torus. Finally, we use the 5 PCs to define a new classification scheme using 5D Gaussian mixtures modelling and trained on widely used optical classifications. The five PCs, average spectra for the four classifications and the code to classify objects are made available at: http://www.phys.susx.ac.uk/~pdh21/PCA/Comment: 11 pages, 12 figures, accepted for publication in MNRA

Renewable Energy Stocks\u27 Performance and Climate Risk: An Empirical Analysis

This article studies the relationship between renewable energy stocks’ performance and climate risk. It shows that publicly held renewable energy stocks underperform as a reaction to climate policy information releases, modeled by feed-in tariff (FIT) legislation announcements. The study examined stock price behaviors 2 days before and 30 days after FIT policy announcements. The stock sample used in the study has 3702 firm-day combinations, which included 180 cleantech firms and 32 events from 2007 to 2017. Based on the residual analysis of the sample’s abnormal return, it indicated that the FIT announcements are associated with significant declines in returns. The cumulative abnormal return until Day 18 was a significant −0.83%, while the average abnormal return on the day was −0.16% at normal levels. The study partially excluded the likelihood of a transitory result by varying the measurement horizon. It also adopted both the market model and the Fama–French three-factor models to rule out model misspecification when estimating abnormal returns and thus increased the robustness. In fact, the results were stable to changes in estimating the model’s specifications. In addition, the study compared the portfolio’s performance with mimicking portfolios in terms of size, book-to-market equity (BE/ME), and the firms’ geographic location. It demonstrated that the documented anomaly of the portfolio of renewable energy companies is robust