53 research outputs found
The role of the most luminous, obscured AGN in galaxy assembly at z~2
We present HST WFC3 F160W imaging and infrared spectral energy distributions
for twelve extremely luminous, obscured AGN at , selected via "Hot,
Dust Obscured" mid-infrared colors. Their infrared luminosities span
L, making them among the most luminous objects in
the Universe at . In all cases the infrared emission is consistent with
arising at least in most part from AGN activity. The AGN fractional
luminosities are higher than those in either sub-millimeter galaxies, or AGN
selected via other mid-infrared criteria. Adopting the , M and
morphological parameters, together with traditional classification boundaries,
infers that three quarters of the sample as mergers. Our sample do not,
however, show any correlation between the considered morphological parameters
and either infrared luminosity or AGN fractional luminosity. Moreover, their
asymmetries and effective radii are distributed identically to those of massive
galaxies at . We conclude that our sample is not preferentially
associated with mergers, though a significant merger fraction is still
plausible. Instead, we propose that our sample are examples of the massive
galaxy population at that harbor a briefly luminous, "flickering" AGN,
and in which the and M values have been perturbed, due to either the
AGN, and/or the earliest formation stages of a bulge in an inside-out manner.
Furthermore, we find that the mass assembly of the central black holes in our
sample leads the mass assembly of any bulge component. Finally, we speculate
that our sample represent a small fraction of the immediate antecedents of
compact star-forming galaxies at .Comment: ApJ, accepted. Updated to reflect the accepted versio
RamPantry: A Model for Sustainability
The VCU RamPantry: Sustainability project’s mission is to develop a comprehensive system to foster a sustainable food pantry model which will reduce food insecurity among VCU students. Food insecurity can affect anyone, whether they are an on-campus student who has run out of meal swipes or an off-campus student who is facing a financially challenging time. Food insecurity may cause anxiety, depression, poor judgement, and may lead to larger problems related to physical health due to lack of nutrition. All of these factors can negatively impact student retention. A sustainable food pantry can mitigate these risks by providing basic food items to students in need. There is a community need for such a program, but the need for this service is greater than what the current RamPantry structure can support. For this project, our team will present a 3-year proposed plan which will include: seeking to find a more permanent location for the organization; assisting with development of operations and procedural manuals; and creating development strategy to increase donations while bringing this need to the attention of the Richmond community. While there are many VCU students who can benefit from RamPantry, we also have many community members who can contribute in a number of ways including the use of Volunteer Service/Community Service leave and hosting departmental food drives
Optimisation and modelling of anaerobic digestion of whiskey distillery/brewery wastes after combined chemical and mechanical pre-treatment
Whiskey distillery waste streams consisting of pot ale (liquid residue) and spent grain (solid residue) are high strength organic wastes and suitable feedstock for anaerobic digestion (AD) from both economic and environmental stand points. Anaerobic digestion of pot ale and pot ale/spent grain mixtures (with mixing ratios of 1:1, 1:3, and 1:5 by wet weight) was performed after implementation of a novel hybrid pre-treatment (combined chemical and mechanical) in order to modify lignocellulosic structure and ultimately enhance digestion yield. Lignin, hemicellulose, and cellulose fractions were determined before and after chemical pre-treatment. Effects of different inoculum rates (10–30–50% on wet basis) and beating times (0–7.5–15 min) on anaerobic digestion of pot ale alone and of pot ale/spent grain mixtures were investigated in lab scale batch mode with a major focus of optimising biogas yield by using response surface methodology (RSM) in Design Expert Software. The highest biogas yields of 629 ± 8.5 mL/g vs. (51.3% CH4) and 360 ± 10 mL/g vs. (55.0 ± 0.4) with anaerobic digestion of pot ale alone and spent grain mix after 1M NaOH and 7.5 min beating pre-treatments with 50% inoculum ratio respectively. The optimum digestion conditions to maximise the biogas quality and quantity were predicted as 10 and 13 min beating times and 32 and 38 ◦C digestion temperatures for anaerobic digestion of pot ale alone and spent grain mix respectively
Young children, gender and the heterosexual matrix
In this paper I consider the adult focus of current mainstream gender theory. I relate this to how the concept of the heterosexual matrix originates in a social contract which excludes children from civil society. I argue that this exclusion is problematic both for theoretical reasons and from the perspective of children themselves. I start by discussing the nature of the heterosexual matrix and its foundations. I consider the implications for participation which arise from being named as a child, how that affects children’s attempts to claim participation in civil society, and how this is related to children’s naming of themselves as gendered. I then briefly consider the possibility that, because of their exclusion, children might also be considered to be exempt from the heterosexual matrix. However, I argue, there is considerable evidence that children are actively sexual beings who also work hard to claim inclusion in local practices of heterosexuality. I end by suggesting that there are three key reasons for this: that the discourses of normative sexuality provide children with a language to express sexual feelings; that self-insertion in the heterosexual matrix is a way for children to claim rights to participation; and that taking up heterosexual formations is a means whereby children can experience the power of naming themselves as part of the social world
Challenges Using Extrapolated Family-level Macroinvertebrate Metrics in Moderately Disturbed Tropical Streams: a Case-study From Belize
Family-level biotic metrics were originally designed to rapidly assess gross organic pollution effects, but came to be regarded as general measures of stream degradation. Improvements in water quality in developed countries have reignited debate about the limitations of family-level taxonomy to detect subtle change, and is resulting in a shift back towards generic and species-level analysis to assess smaller effects. Although the scale of pollution characterizing past condition of streams in developed countries persists in many developing regions, some areas are still considered to be only moderately disturbed. We sampled streams in Belize to investigate the ability of family-level macroinvertebrate metrics to detect change in stream catchments where less than 30% of forest had been cleared. Where disturbance did not co-vary with natural gradients of change, and in areas characterized by low intensity activities, none of the metrics tested detected significant change, despite evidence of environmental impacts. We highlight the need for further research to clarify the response of metrics to disturbance over a broader study area that allows replication for confounding sources of natural variation. We also recommend research to develop more detailed understanding of the taxonomy and ecology of Neotropical macroinvertebrates to improve the robustness of metric use
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Uracil recognition by replicative DNA polymerases is limited to the archaea, not occurring with bacteria and eukarya
Family B DNA polymerases from archaea such as Pyrococcus furiosus, which live at temperatures ∼100°C, specifically recognize uracil in DNA templates and stall replication in response to this base. Here it is demonstrated that interaction with uracil is not restricted to hyperthermophilic archaea and that the polymerase from mesophilic Methanosarcina acetivorans shows identical behaviour. The family B DNA polymerases replicate the genomes of archaea, one of the three fundamental domains of life. This publication further shows that the DNA replicating polymerases from the other two domains, bacteria (polymerase III) and eukaryotes (polymerases δ and ε for nuclear DNA and polymerase γ for mitochondrial) are also unable to recognize uracil. Uracil occurs in DNA as a result of deamination of cytosine, either in G:C base-pairs or, more rapidly, in single stranded regions produced, for example, during replication. The resulting G:U mis-pairs/single stranded uracils are promutagenic and, unless repaired, give rise to G:C to A:T transitions in 50% of the progeny. The confinement of uracil recognition to polymerases of the archaeal domain is discussed in terms of the DNA repair pathways necessary for the elimination of uracil
An Indo-Pacifc coral spawning database
The discovery of multi-species synchronous spawning of scleractinian corals on the Great Barrier Reef in the 1980s stimulated an extraordinary effort to document spawning times in other parts of the globe. Unfortunately, most of these data remain unpublished which limits our understanding of regional and global reproductive patterns. The Coral Spawning Database (CSD) collates much of these disparate data into a single place. The CSD includes 6178 observations (3085 of which were unpublished) of the time or day of spawning for over 300 scleractinian species in 61 genera from 101 sites in the Indo-Pacific. The goal of the CSD is to provide open access to coral spawning data to accelerate our understanding of coral reproductive biology and to provide a baseline against which to evaluate any future changes in reproductive phenology
Deep Convective Microphysics Experiment (DCMEX) coordinated aircraft and ground observations: microphysics, aerosol, and dynamics during cumulonimbus development
Cloud feedbacks associated with deep convective anvils remain highly uncertain. In part, this uncertainty arises from a lack of understanding of how microphysical processes influence the cloud radiative effect. In particular, climate models have a poor representation of microphysics processes, thereby encouraging the collection and study of observation data to enable better representation of these processes in models. As such, the Deep Convective Microphysics Experiment (DCMEX) undertook an in situ aircraft and ground-based measurement campaign of New Mexico deep convective clouds during July–August 2022. The campaign coordinated a broad range of instrumentation measuring aerosol, cloud physics, radar, thermodynamics, dynamics, electric fields, and weather. This paper introduces the potential data user to DCMEX observational campaign characteristics, relevant instrument details, and references to more detailed instrument descriptions. Also included is information on the structure and important files in the dataset in order to aid the accessibility of the dataset to new users. Our overview of the campaign cases illustrates the complementary operational observations available and demonstrates the breadth of the campaign cases observed. During the campaign, a wide selection of environmental conditions occurred, ranging from dry, northerly air masses with low wind shear to moist, southerly air masses with high wind shear. This provided a wide range of different convective growth situations. Of 19 flight days, only 2 d lacked the formation of convective cloud. The dataset presented (https://doi.org/10.5285/B1211AD185E24B488D41DD98F957506C; Facility for Airborne Atmospheric Measurements et al., 2024) will help establish a new understanding of processes on the smallest cloud- and aerosol-particle scales and, once combined with operational satellite observations and modelling, can support efforts to reduce the uncertainty of anvil cloud radiative impacts on climate scales
The Role of Inflammatory Mediators in the Pathogenesis of Otitis Media and Sequelae
This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K+ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued
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