Biotic and abiotic factors influencing infestation levels of the arundo leafminer, Lasioptera donacis, in its native range in Mediterranean Europe

Lasioptera donacis is a biological control agent of Arundo donax, which is an invasive weed in the riparian hab-itats of the Rio Grande Basin of Texas and Northern Mexico. Field research was conducted in the native range of L. donacis in Mediterranean Europe to evaluate the biotic and abiotic factors that influence its local infestation levels. Lasioptera donacis feeding damage was documented on 40.4 and 67.8 % of dead and decaying leaf sheaths respectively across all sites. Lasioptera donacis was active in all locations including highly disturbed sites, but showed a slight preference for sites near running freshwater sources and lower infestation levels adjacent to salt water sources. The environmental preferences of L. donacis in Europe are similar to conditions in the Rio Grande Basin and Southwestern U.S. where A. donax is invasive

Triggering Active Galactic Nuclei in galaxy clusters

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We model the triggering of active galactic nuclei (AGN) in galaxy clusters using the semianalytic galaxy formation model SAGE. We prescribe triggering methods based on the ram pressure galaxies experience as they move throughout the intracluster medium, which is hypothesized to trigger star formation and AGN activity. The clustercentric radius and velocity distribution of the simulated active galaxies produced by thesemodels are compared with those of AGN and galaxies with intense star formation from a sample of low-redshift relaxed clusters from the Sloan Digital Sky Survey. The ram pressure triggering model that best explains the clustercentric radius and velocity distribution of these observed galaxies has AGN and star formation triggered if 2.5 × 10 -14 Pa 2P internal; this is consistent with expectations from hydrodynamical simulations of ram-pressure-induced star formation. Our results show that ram pressure is likely to be an important mechanism for triggering star formation and AGN activity in clusters.Peer reviewe

The host galaxies of z=7 quasars: predictions from the BlueTides simulation

We examine the properties of the host galaxies of $z=7$ quasars using the large volume, cosmological hydrodynamical simulation BlueTides. We find that the 10 most massive black holes and the 191 quasars in the simulation (with $M_{\textrm{UV,AGN}}<M_{\textrm{UV,host}}$) are hosted by massive galaxies with stellar masses $\log(M_\ast/M_\odot)=10.8\pm0.2$, and $10.2\pm0.4$, which have large star formation rates, of $513\substack{+1225 \\ -351}M_\odot/\rm{yr}$ and $191\substack{+288 \\ -120}M_\odot/\rm{yr}$, respectively. The hosts of the most massive black holes and quasars in BlueTides are generally bulge-dominated, with bulge-to-total mass ratio $B/T\simeq0.85\pm0.1$, however their morphologies are not biased relative to the overall $z=7$ galaxy sample. We find that the hosts of the most massive black holes and quasars are significantly more compact, with half-mass radii $R_{0.5}=0.41\substack{+0.18 \\ -0.14}$ kpc and $0.40\substack{+0.11 \\ -0.09}$ kpc respectively; galaxies with similar masses and luminosities have a wider range of sizes with a larger median value, $R_{0.5}=0.71\substack{+0.28 \\ -0.25}$ kpc. We make mock James Webb Space Telescope (JWST) images of these quasars and their host galaxies. We find that distinguishing the host from the quasar emission will be possible but still challenging with JWST, due to the small sizes of quasar hosts. We find that quasar samples are biased tracers of the intrinsic black hole--stellar mass relation, following a relation that is 0.2 dex higher than that of the full galaxy sample. Finally, we find that the most massive black holes and quasars are more likely to be found in denser environments than the typical $M_{\textrm{BH}}>10^{6.5}M_\odot$ black hole, indicating that minor mergers play at least some role in growing black holes in the early Universe.Comment: 19 pages, 20 figures. Accepted for publication in MNRA

First Light And Reionisation Epoch Simulations (FLARES) : IV. The size evolution of galaxies at z ≥ 5

We present the intrinsic and observed sizes of galaxies at z >= 5 in the First Light And Reionisation Epoch Simulations (flares). We employ the large effective volume of flares to produce a sizeable sample of high-redshift galaxies with intrinsic and observed luminosities and half-light radii in a range of rest-frame ultraviolet (UV) and visual photometric bands. This sample contains a significant number of intrinsically ultracompact galaxies in the far-UV (1500 angstrom), leading to a negative intrinsic far-UV size-luminosity relation. However, after the inclusion of the effects of dust these same compact galaxies exhibit observed sizes that are as much as 50 times larger than those measured from the intrinsic emission, and broadly agree with a range of observational samples. This increase in size is driven by the concentration of dust in the core of galaxies, heavily attenuating the intrinsically brightest regions. At fixed luminosity we find a galaxy size redshift evolution with a slope of m = 1.21-1.87 depending on the luminosity sample in question, and we demonstrate the wavelength dependence of the size-luminosity relation that will soon be probed by the James Webb Space Telescope.Peer reviewe

THP-1 macrophage cholesterol efflux is impaired by palmitoleate through Akt activation.

Lipoprotein lipase (LPL) is upregulated in atherosclerotic lesions and it may promote the progression of atherosclerosis, but the mechanisms behind this process are not completely understood. We previously showed that the phosphorylation of Akt within THP-1 macrophages is increased in response to the lipid hydrolysis products generated by LPL from total lipoproteins. Notably, the free fatty acid (FFA) component was responsible for this effect. In the present study, we aimed to reveal more detail as to how the FFA component may affect Akt signalling. We show that the phosphorylation of Akt within THP-1 macrophages increases with total FFA concentration and that phosphorylation is elevated up to 18 hours. We further show that specifically the palmitoleate component of the total FFA affects Akt phosphorylation. This is tied with changes to the levels of select molecular species of phosphoinositides. We further show that the total FFA component, and specifically palmitoleate, reduces apolipoprotein A-I-mediated cholesterol efflux, and that the reduction can be reversed in the presence of the Akt inhibitor MK-2206. Overall, our data support a negative role for the FFA component of lipoprotein hydrolysis products generated by LPL, by impairing macrophage cholesterol efflux via Akt activation

Observing the host galaxies of high-redshift quasars with JWST: predictions from the BLUETIDES simulation

The bright emission from high-redshift quasars completely conceals their host galaxies in the rest-frame ultraviolet/optical, with detection of the hosts in these wavelengths eluding even the Hubble Space Telescope (HST) using detailed point spread function (PSF) modelling techniques. In this study, we produce mock images of a sample of z = 7 quasars extracted from the BLUETIDES simulation, and apply Markov chain Monte Carlo-based PSF modelling to determine the detectability of their host galaxies with the James Webb Space Telescope (JWST). While no statistically significant detections are made with HST, we predict that at the same wavelengths and exposure times JWST NIRCam imaging will detect ∼ 50 per cent of quasar host galaxies. We investigate various observational strategies, and find that NIRCam wide-band imaging in the long-wavelength filters results in the highest fraction of successful quasar host detections, detecting > 80 per cent of the hosts of bright quasars in exposure times of 5 ks. Exposure times of > 5 ks are required to detect the majority of host galaxies in the NIRCam wide-band filters, however, even 10 ks exposures with MIRI result in < 30 per cent successful host detections. We find no significant trends between galaxy properties and their detectability. The PSF modelling can accurately recover the host magnitudes, radii, and spatial distribution of the larger scale emission, when accounting for the central core being contaminated by residual quasar flux. Care should be made when interpreting the host properties measured using PSF modelling

The JWST Hubble Sequence: The Rest-frame Optical Evolution of Galaxy Structure at 1.5 < z < 6.5

© 2023. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/We present results on the morphological and structural evolution of a total of 3956 galaxies observed with JWST at 1.5 109 M ⊙ at z > 3 are not dominated by irregular and peculiar structures, either visually or quantitatively, as previously thought. We find a strong dominance of morphologically selected disk galaxies up to z = 6 in this mass range. We also find that the stellar mass and star formation rate densities are dominated by disk galaxies up to z ∼ 6, demonstrating that most stars in the Universe were likely formed in a disk galaxy. We compare our results to theory to show that the fraction of types we find is predicted by cosmological simulations, and that the Hubble Sequence was already in place as early as one billion years after the Big Bang. Additionally, we make our visual classifications public for the community.Peer reviewe