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A Toxicological Basis to Derive a Generic Interspecies Uncertainty Factor.
A new method is proposed to derive the size of the interspecies uncertainty factor (UF) that is toxicologically and statistically based. The method involves quantifying interspecies variation in susceptibility to numerous toxic substances via the use of binary interspecies comparisons that are converted to a 95% UF. This interspecies UF represents an estimate of the upper 95% of the population of 95% prediction intervals (PI) for binary interspecies comparisons within four categories of phylogenetic relatedness (species within genus, genera within family, families within order, orders within class). The 95% interspecies UFs range from a low of 10 for species within genus up to 65 for orders within class. Most mammalian toxicology studies involving mice, rats, cats, dogs, gerbils, and rabbits are orders-within- class categories for human risk assessment and would be provided a 65-fold UF. Larger or smaller interspecies UF values could be selected on the level of protection desired
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Cone Spacing Correlates With Retinal Thickness and Microperimetry in Patients With Inherited Retinal Degenerations.
PurposeTo determine whether high-resolution retinal imaging measures of macular structure correlate with visual function over 36 months in retinal degeneration (RD) patients and normal subjects.MethodsTwenty-six eyes of 16 RD patients and 16 eyes of 8 normal subjects were studied at baseline; 15 eyes (14 RD) and 11 eyes (6 normal) were studied 36 months later. Adaptive Optics Scanning Laser Ophthalmoscopy (AOSLO) was used to identify regions of interest (ROIs) with unambiguous cones at baseline to measure cone spacing. AOSLO images were aligned with spectral-domain optical coherence tomography (SD-OCT) and fundus-guided microperimetry results to correlate structure and function at the ROIs. SD-OCT images were segmented to measure inner segment (IS) and outer segment (OS) thickness. Correlations between cone spacing, IS and OS thickness and sensitivity were assessed using Spearman correlation coefficient ρ with bootstrap analyses clustered by person.ResultsCone spacing (ρ = 0.57, P < 0.001) and macular sensitivity (ρ = 0.19, P = 0.14) were significantly correlated with eccentricity in patients. Controlling for eccentricity, cone spacing Z-scores were inversely correlated with IS (ρ = -0.29, P = 0.002) and OS thickness (ρ = -0.39, P < 0.001) in RD patients only, and with sensitivity in normal subjects (ρ = -0.22, P < 0.001) and RD patients (ρ = -0.38, P < 0.001). After 36 months, cone spacing increased (P < 0.001) and macular sensitivity decreased (P = 0.007) compared to baseline in RD patients.ConclusionsCone spacing increased and macular sensitivity declined significantly in RD patients over 36 months. High resolution images of cone structure correlated with retinal sensitivity, and may be appropriate outcome measures for clinical trials in RD
Adult attachment style across individuals and role-relationships: Avoidance is relationship-specific, but anxiety shows greater generalizability
A generalisability study examined the hypotheses that avoidant attachment, reflecting the representation of others, should be more relationship-specific (vary across relationships more than across individuals), while attachment anxiety, reflecting self-representation, should be more generalisable across a person’s relationships. College students responded to 6-item questionnaire measures of these variables for 5 relationships (mother, father, best same-gender friend, romantic partner or best opposite-gender friend, other close person), on 3 (N = 120) or 2 (N = 77) occasions separated by a few weeks. Results supported the hypotheses, with the person variance component being larger than the relationship-specific component for anxiety, and the opposite happening for avoidance. Anxiety therefore seems not to be as relationship-specific as previous research suggested. Possible reasons for discrepancies between the current and previous studies are discussed
On the Iwasawa-Taniguchi effect of radio-quiet AGN
The existence of an anti-correlation between the Equivalent Width (EW) of the
neutral narrow core of the iron Kalpha emission line and the 2-10 keV
luminosity (the so-called `X-ray Baldwin' or `Iwasawa-Taniguchi' effect) has
been debated in the last years. We aim at testing this claim on the largest
catalogue of radio quiet AGN high-quality X-ray spectra ever published. The
final sample comprises 157 objects. We search for a relation of the iron line
EW not only with the X-ray luminosity, but also with the Black Hole mass, the
Eddington ratio and the cosmological distance. The data presented here were
analyzed homogeneously, all spectra are from the same instrument and with high
Signal-to-Noise Ratio. A linear censored fit on the EW versus 2-10 keV
luminosity is highly significant and yields , where is the EW of the neutral iron
Kalpha line in eV and is the 2-10 keV X-ray luminosity in units of
erg s. The anti-correlation with the Eddington ratio is also
very significant, while no dependence of the iron EW on the BH mass is
apparent.Comment: 4 pages, 4 figures, accepted for publication in Astronomy and
Astrophysics Letter
Quasars as Cosmological Probes: The Ionizing Continuum, Gas Metallicity and the EW-L Relation
Using a realistic model for line emission from the broad emission line
regions of quasars, we are able to reproduce the previously observed
correlations of emission-line ratios with the shape of the spectral energy
distribution (SED). In agreement with previous studies, we find that the
primary driving force behind the Baldwin Effect (EW ~ L^beta, beta < 0) is a
global change in the SED with quasar luminosity, in that more luminous quasars
must have characteristically softer ionizing continua. This is completely
consistent with observations that show correlations between L_uv, alpha_ox,
alpha_uvx, line ratios and EWs. However, to explain the complete lack of a
correlation in the EW(NV)--L_uv diagram we propose that the more luminous
quasars have characteristically larger gas metallicities (Z). As a secondary
element, nitrogen's rapidly increasing abundance with increasing Z compensates
for the losses in EW(NV) emitted by gas illuminated by softer continua in
higher luminosity quasars. A characteristic relationship between Z and L has an
impact on the EW--L_uv relations for other lines as well. For a fixed SED, an
increasing gas metallicity reduces the EW of the stronger metal lines (the gas
cools) and that of Ly_alpha and especially HeII (because of the increasing
metal opacity), while the weaker lines (e.g., CIII] 1909) generally respond
positively. The interplay between the effects of a changing SED and Z with L
results in the observed luminosity dependent spectral variations. All of the
resulting dependences on L_uv are within the range of the observed slopes.Comment: 11 pages, 3 figures, AASTeX aas2pp4.sty, accepted for publication in
Ap
Can photo-ionization explain the decreasing fraction of X-ray obscured AGN with luminosity?
Chandra and XMM surveys show that the fraction of obscured AGN decreases
rapidly with increasing luminosity. Although this is usually explained by
assuming that the covering factor of the central engine is much smaller at
luminous QSOs, the exact origin of this effect remains unknown. We perform toy
simulations to test whether photo-ionisation of the obscuring screen in the
presence of a strong radiation field can reproduce this effect. In particular,
we create X-ray spectral simulations using a warm absorber model assuming a
range of input column densities and ionization parameters. We fit instead the
simulated spectra with a simple cold absorption power-law model that is the
standard practice in X-ray surveys. We find that the fraction of absorbed AGN
should fall with luminosity as in rough agreement with the
observations. Furthermore, this apparent decrease in the obscuring material is
consistent with the dependence of the FeK narrow-line equivalent width
on luminosity, ie. the X-ray Baldwin effect.Comment: 7 pages 4 figures A&A accepte
Microsporidia-nematode associations in methane seeps reveal basal fungal parasitism in the deep sea
The deep sea is Earth’s largest habitat but little is known about the nature of deep-sea parasitism. In contrast to a few characterized cases of bacterial and protistan parasites, the existence and biological significance of deep-sea parasitic fungi is yet to be understood. Here we report the discovery of a fungus-related parasitic microsporidium, Nematocenator marisprofundi n. gen. n. sp. that infects benthic nematodes at Pacific Ocean methane seeps on the Pacific Ocean floor. This infection is species-specific and has been temporally and spatially stable over two years of sampling, indicating an ecologically consistent host-parasite interaction. A high distribution of spores in the reproductive tracts of infected males and females and their absence from host nematodes’ intestines suggests a sexual transmission strategy in contrast to the fecal-oral transmission of most microsporidia. N. marisprofundi targets the host’s body wall muscles causing cell lysis, and in severe infection even muscle filament degradation. Phylogenetic analyses placed N. marisprofundi in a novel and basal clade not closely related to any described microsporidia clade, suggesting either that microsporidia-nematode parasitism occurred early in microsporidia evolution or that host specialization occurred late in an ancient deep-sea microsporidian lineage. Our findings reveal that methane seeps support complex ecosystems involving interkingdom interactions between bacteria, nematodes, and parasitic fungi and that microsporidia parasitism exists also in the deep sea biosphere
Elevated expression of the chemokine-scavenging receptor D6 is associated with impaired lesion development in psoriasis
D6 is a scavenging-receptor for inflammatory CC chemokines that are essential for resolution of inflammatory responses in mice. Here, we demonstrate that D6 plays a central role in controlling cutaneous inflammation, and that D6 deficiency is associated with development of a psoriasis-like pathology in response to varied inflammatory stimuli in mice. Examination of D6 expression in human psoriatic skin revealed markedly elevated expression in both the epidermis and lymphatic endothelium in "uninvolved" psoriatic skin (ie, skin that was more than 8 cm distant from psoriatic plaques). Notably, this increased D6 expression is associated with elevated inflammatory chemokine expression, but an absence of plaque development, in uninvolved skin. Along with our previous observations of the ability of epidermally expressed transgenic D6 to impair cutaneous inflammatory responses, our data support a role for elevated D6 levels in suppressing inflammatory chemokine action and lesion development in uninvolved psoriatic skin. D6 expression consistently dropped in perilesional and lesional skin, coincident with development of psoriatic plaques. D6 expression in uninvolved skin also was reduced after trauma, indicative of a role for trauma-mediated reduction in D6 expression in triggering lesion development. Importantly, D6 is also elevated in peripheral blood leukocytes in psoriatic patients, indicating that upregulation may be a general protective response to inflammation. Together our data demonstrate a novel role for D6 as a regulator of the transition from uninvolved to lesional skin in psoriasis
The Fundamental Planes of E+A galaxies and GALEX UV-excess early-type galaxies: Revealing their intimate connection
Strong Balmer absorption lines and the lack of Ha and [OII] emission lines
signify that E+As are post-starburst systems. Recent studies suggest that E+As
may undergo the transition from the `blue cloud' to the `red sequence' and
eventually migrate to red sequence ETGs. An observational validation of this
scenario is to identify the intervening galaxy population between E+As and the
red-sequence. Motivated by recent findings with GALEX that a large fraction of
ETGs exhibit UV-excess as a sign of RSF, we investigate the possible connection
of the UV-excess galaxies to E+As. In particular, we examine the FP scaling
relations of the largest sample of ~1,000 E+As selected from the SDSS and
~20,000 morphologically-selected SDSS ETGs with GALEX UV data. The FP
parameters, combined with stellar population indicators, reveal a certain group
of UV-excess ETGs that bridges between E+As and quiescent red galaxies. The
newly identified galaxies are the post-starburst systems characterized by
UV-excess but no Ha emission. This is a conceptual generalisation of "E+A", in
that the Balmer absorption line in the "E+A" definition is replaced with
UV-optical colours that are far more sensitive to RSF than the Balmer lines. We
refer to these UV-excess galaxies as "E+a" galaxies, which stands for
elliptical ("E") galaxies with a minority of A-type ("a") young stars. The
species are either (1) galaxies that experienced starbursts weaker than those
observed in E+As (1~10% of E+As, "mild E+As") or (2) the products of passively
evolved E+As after quenching star formation quite a while ago (~1 Gyr, "old
E+As"). We suggest that the latter type of E+a galaxies represents the most
recent arrival to the red sequence in the final phase of the "E+A" to "red
early-type" transition. (Abridged)Comment: 15 pages, 15 figures, Accepted for publication in MNRA
Broad-line Balmer Decrements in Blue Active Galactic Nuclei
We have investigated the broad-line Balmer decrements (Halpha/Hbeta) for a
large, homogeneous sample of Seyfert 1 galaxies and QSOs using spectroscopic
data obtained in the Sloan Digital Sky Survey. The sample, drawn from the
Fourth Data Release, comprises 446 low redshift (z < 0.35) active galactic
nuclei (AGN) that have blue optical continua as indicated by the spectral
slopes in order to minimize the effect of dust extinction. We find that (i) the
distribution of the intrinsic broad-line Halpha/Hbeta ratio can be well
described by log-Gaussian, with a peak at Halpha/Hbeta=3.06 and a standard
deviation of about 0.03 dex only; (ii) the Balmer decrement does not correlate
with AGN properties such as luminosity, accretion rate, and continuum slope,
etc.; (iii) on average, the Balmer decrements are found to be only slightly
larger in radio-loud sources (3.37) and sources having double-peaked
emission-line profiles (3.27) compared to the rest of the sample. We therefore
suggest that the broad-line Halpha/Hbeta ratio can be used as a good indicator
for dust extinction in the AGN broad-line region; this is especially true for
radio-quiet AGN with regular emission-line profiles, which constitute the vast
majority of the AGN population.Comment: To appear in MNRAS. The data and the fitted parameters for the
decomposed spectral components (continuum, FeII and other emission lines) of
the 446 blue AGNs are available at
http://staff.ustc.edu.cn/~xbdong/Data_Release/blueAGN_DR4
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