1,255 research outputs found
Structure determination of new algal toxins using NMR methods
Shellfish are considered a delicacy by many consumers. In NZ, as in many overseas countries, there is a now thriv¬ing shellfish industry servicing both domestic and inter-national markets. Periodically shellfish accumulate harm¬ful levels of a variety of algal toxins, including domoic acid, yessotoxins, pectenotoxins and brevetoxins. When this occurs, regulatory authorities may impose harvesting closures which have a consequential economic impact on both farmers and staff employed to harvest and market shellfish products
furor illa et movit Erinys: The Presentation and Agency of Tisiphone in Statius' Thebaid
The purpose of this paper is to provide new insight into the Fury Tisiphone, who prominently appears in Statius’ Thebaid. I examine the development of the Erinys from its earliest origins in Homer to, as I argue, its literary zenith in Statius. Such an approach demonstrates how Tisiphone’s depiction by Statius was informed by his epic predecessors, yet how her role in the Thebaid was unique and more comprehensive than other characterizations of the Furies in Greek or Latin literature. My intent is for scholars to gain a new appreciation for the power of Tisiphone, a vital character of the Thebaid, her role in the poem, and how that role compares with other accounts from ancient literature
Recalibrating the cosmic star formation history
The calibrations linking observed luminosities to the star formation rate
depend on the assumed stellar population synthesis model, initial mass
function, star formation and metal enrichment history, and whether reprocessing
by dust and gas is included. Consequently the shape and normalisation of the
inferred cosmic star formation history is sensitive to these assumptions. Using
v2.2.1 of the Binary Population and Spectral Synthesis (\bpass) model we
determine a new set of calibration coefficients for the ultraviolet,
thermal-infrared, and, hydrogen recombination lines. These ultraviolet and
thermal infrared coefficients are 0.15-0.2 dex higher than those widely
utilised in the literature while the H coefficient is dex
larger. These differences arise in part due to the inclusion binary evolution
pathways but predominantly reflect an extension in the IMF to 300
and a change in the choice of reference metallicity. We use these new
coefficients to recalibrate the cosmic star formation history, and find
improved agreement between the integrated cosmic star formation history and the
in-situ measured stellar mass density as a function of redshift. However, these
coefficients produce new tension between star formation rate densities inferred
from the ultraviolet and thermal-infrared and those from H.Comment: 7 pages, 8 figures, accepted for publication in MNRA
Nebular Line Emission During the Epoch of Reionization
Nebular emission lines associated with galactic HII regions carry information
about both physical properties of the ionised gas and the source of ionising
photons as well as providing the opportunity of measuring accurate redshifts
and thus distances once a cosmological model is assumed. While nebular line
emission has been extensively studied at lower redshift there are currently
only few constraints within the epoch of reionisation (EoR, ), chiefly due
to the lack of sensitive near-IR spectrographs. However, this will soon change
with the arrival of the Webb Telescope providing sensitive near-IR spectroscopy
covering the rest-frame UV and optical emission of galaxies in the EoR. In
anticipation of Webb we combine the large cosmological hydrodynamical
simulation Bluetides with photoionisation modelling to predict the nebular
emission line properties of galaxies at . We find good agreement
with the, albeit limited, existing direct and indirect observational
constraints on equivalent widths though poorer agreement with luminosity
function constraints.Comment: 17 pages, accepted to MNRAS, significant modification from v1.0 data
available at https://stephenmwilkins.github.io/BluetidesEmissionLines_Public
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Applications of Conditional Topic Models to Species Distribution Prediction
The topic of species distribution modelling has been on of increasing interest in
recent years. As climate change is becoming of even more interest to researchers,
more tools are needed to better analyze and predict various climate change scenarios.
One particular area of interest is that of species distribution modeling. Species
distribution modelling addresses the problem of determining either the fundamental
or the realized niche of a species, either at the current time or projecting into
the past or future. Species distribution models (SDMs) are seen as a potentially
powerful tool both for applied policy decisions like reservation design and theorectical
understanding, discovering what factors are most important in determining
the fundamental niche of a species, as well as the extent to which various factors
determine how much of that niche is realized.
Currently, almost all SDMs focus on a single species at a time. For any given
species, a model is developed and trained for that particular species. An advantage
of this approach is that is keep computational costs down relative to a broader
model. There is, however, potential in the idea that by modeling multiple species
at once, mutual information between species can be leveraged to provide more accurate
modeling while offering insights into the nature of the relationships between
specific species. This paper examines the attempt to use one such model for doing species distribution modeling on several species at once
Acute exposure to ultraviolet radiation targets proteins involved in collagen fibrillogenesis
Introduction: Exposure to chronic, low-dose UV irradiation (UVR) can lead to premature ageing of the skin. Understanding which proteins are affected by acute UVR and photo-dynamically produced reactive oxygen species (ROS) could help to inform strategies to delay photoageing. Conventional biochemical analyses can be used to characterize UVR/ROS-induced damage on a protein-by-protein basis and we have previously shown using SDS-PAGE that collagen I and plasma fibronectin are respectively resistant and susceptible to physiological doses of UVR. The aim of this study was to screen a complex proteome for UVR-affected proteins.Methods: This study employed a sensitive mass spectrometry technique (peptide location fingerprinting: PLF) which can identify structure associated differences following trypsin digestion to characterize the impact of UVR exposure on purified collagen I and tissue fibronectin and to identify UVR-susceptible proteins in an ECM-enriched proteome.Results: Using LC/MS-MS and PLF we show that purified mature type-I collagen is resistant to UVR, whereas purified tissue fibronectin is susceptible. UV irradiation of a human dermal fibroblast-deposited ECM-enriched proteome in vitro, followed by LC/MS-MS and PLF analysis revealed two protein cluster groups of UV susceptible proteins involved in i) matrix collagen fibril assembly and ii) protein translation and motor activity. Furthermore, PLF highlighted UV susceptible domains within targeted matrix proteins, suggesting that UV damage of matrix proteins is localized.Discussion: Here we show that PLF can be used to identify protein targets of UVR and that collagen accessory proteins may be key targets in UVR exposed tissues
Gawad Kalinga Enchanted Farm, Philippines
Poster created by students in the 2016 IWU Freeman Asia Internship Program
Characterising and identifying galaxy protoclusters
We study the characteristics of galaxy protoclusters using the latest L-GALAXIES semi-analytic model. Searching for protoclusters on a scale of ∼10 cMpc gives an excellent compromise between the completeness and purity of their galaxy populations, leads to high distinction from the field in overdensity space, and allows accurate determination of the descendant cluster mass. This scale is valid over a range of redshifts and selection criteria. We present a procedure for estimating, given a measured galaxy overdensity, the protocluster probability and its descendant cluster mass for a range of modelling assumptions, particularly taking into account the shape of the measurement aperture. This procedure produces lower protocluster probabilities compared to previous estimates using fixed size apertures. The relationship between active galactic nucleus (AGN) and protoclusters is also investigated and shows significant evolution with redshift; at z ∼ 2, the fraction of protoclusters traced by AGN is high, but the fraction of all AGNs in protoclusters is low, whereas atz ≥ 5 the fraction of protoclusters containing AGN is low, but most AGNs are in protoclusters. We also find indirect evidence for the emergence of a passive sequence in protoclusters at z ∼ 2, and note that a significant fraction of all galaxies reside in protoclusters at z ≥ 2, particularly the most massive
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