2,746 research outputs found
Resolving 3D Disk Orientation using High-Resolution Images: New Constraints on Circumgalactic Gas Inflows
We constrain gas inflow speeds in star-forming galaxies with color gradients
consistent with inside-out disk growth. Our method combines new measurements of
disk orientation with previously described circumgalactic absorption in
background quasar spectra. Two quantities, a position angle and an axis ratio,
describe the projected shape of each galactic disk on the sky, leaving an
ambiguity about which side of the minor axis is tipped toward the observer.
This degeneracy regarding the 3D orientation of disks has compromised previous
efforts to measure gas inflow speeds. We present HST and Keck/LGSAO imaging
that resolves the spiral structure in five galaxies at redshift .
We determine the sign of the disk inclination for four galaxies, under the
assumption that spiral arms trail the rotation. We project models for both
radial infall in the disk plane and circular orbits onto each quasar sightline.
We compare the resulting line-of-sight velocities to the observed velocity
range of Mg II absorption in spectra of background quasars, which intersect the
disk plane at radii between 69 and 115 kpc. For two sightlines, we constrain
the maximum radial inflow speeds as 30-40 km s. We also rule out a
velocity component from radial inflow in one sightline, suggesting that the
structures feeding gas to these growing disks do not have unity covering
factor. We recommend appropriate selection criteria for building larger samples
of galaxy--quasar pairs that produce orientations sensitive to constraining
inflow properties.Comment: 15 pages with 8 figures and 2 tables; accepted for publication in Ap
Kinematics of Circumgalactic Gas: Feeding Galaxies and Feedback
We present observations of 50 pairs of redshift z ~ 0.2 star-forming galaxies
and background quasars. These sightlines probe the circumgalactic medium (CGM)
out to half the virial radius, and we describe the circumgalactic gas
kinematics relative to the reference frame defined by the galactic disks. We
detect halo gas in MgII absorption, measure the equivalent-width-weighted
Doppler shifts relative to each galaxy, and find that the CGM has a component
of angular momentum that is aligned with the galactic disk. No net
counter-rotation of the CGM is detected within 45 degrees of the major axis at
any impact parameter. The velocity offset of the circumgalactic gas correlates
with the projected rotation speed in the disk plane out to disk radii of
roughly 70 kpc. We confirm previous claims that the MgII absorption becomes
stronger near the galactic minor axis and show that the equivalent width
correlates with the velocity range of the absorption. We cannot directly
measure the location of any absorber along the sightline, but we explore the
hypothesis that individual velocity components can be associated with gas
orbiting in the disk plane or flowing radially outward in a conical outflow. We
conclude that centrifugal forces partially support the low-ionization gas and
galactic outflows kinematically disturb the CGM producing excess absorption.
Our results firmly rule out schema for the inner CGM that lack rotation and
suggest that angular momentum as well as galactic winds should be included in
any viable model for the low-redshift CGM.Comment: Accepted for publication in the Astrophysical Journa
Morphological and Rotation Structures of Circumgalactic Mg II Gas in the EAGLE Simulation and the Dependence on Galaxy Properties
Low-ionization-state Mg II gas has been extensively studied in quasar
sightline observations to understand the cool, K gas in the
circumgalactic medium. Motivated by recent observations showing that the Mg II
gas around low-redshift galaxies has significant angular momentum, we use the
high-resolution EAGLE cosmological simulation to analyze the morphological and
rotation structures of the circumgalactic Mg II gas and examine
how they change with the host galaxy properties. Around star-forming galaxies,
we find that the Mg II gas has an axisymmetric instead of a spherical
distribution, and the axis of symmetry aligns with that of the Mg II gas
rotation. A similar rotating structure is less commonly found in the small
sample of simulated quiescent galaxies. We also examine how often Mg II gas
around galaxies selected using a line-of-sight velocity cut includes gas
physically outside of the virial radius (). For example, we
show that at an impact parameter of 100 pkpc, a km s velocity
cut around galaxies with stellar masses of -
(-) selects Mg II gas beyond the virial
radius 80% (6%) of the time. Because observers typically select Mg II gas
around target galaxies using such a velocity cut, we discuss how this issue
affects the study of circumgalactic Mg II gas properties, including the
detection of corotation. While the corotating Mg II gas generally extends
beyond , the Mg II gas outside of the virial radius
contaminates the corotation signal and makes observers less likely to conclude
that gas at large impact parameters (e.g., ) is
corotating.Comment: 26 pages with 18 figures and 3 tables; accepted for publication in
Ap
How Gas Accretion Feeds Galactic Disks
Numerous observations indicate that galaxies need a continuous gas supply to
fuel star formation and explain the star formation history. However, direct
observational evidence of gas accretion remains rare. Using the EAGLE
cosmological hydrodynamic simulation suite, we study cold gas accretion onto
galaxies and the observational signatures of the cold gas kinematics. For EAGLE
galaxies at z=0.27, we find that cold gas accretes onto galaxies
anisotropically with typical inflow speeds between 20 km s and 60 km
s. Most of these galaxies have comparable mass inflow rates and star
formation rates, implying that the cold inflowing gas plausibly accounts for
sustaining the star-forming activities of the galaxies. As motivation for
future work to compare the cold gas kinematics with measurements from quasar
sightline observations, we select an EAGLE galaxy with an extended cold gas
disk, and we probe the cold gas using mock quasar sightlines. We demonstrate
that by viewing the disk edge-on, sightlines at azimuthal angles below
10 and impact parameters out to 60 pkpc can detect cold gas that
corotates with the galaxy disk. This example suggests cold gas disks that
extend beyond the optical disks possibly explain the sightline observations
that detect corotating cold gas near galaxy major axes.Comment: 24 pages, 16 figures; accepted by Ap
Empathy and stress related neural responses in maternal decision making
Mothers need to make caregiving decisions to meet the needs of children, which may or may not result in positive child feedback. Variations in caregivers' emotional reactivity to unpleasant child-feedback may be partially explained by their dispositional empathy levels. Furthermore, empathic response to the child's unpleasant feedback likely helps mothers to regulate their own stress. We investigated the relationship between maternal dispositional empathy, stress reactivity, and neural correlates of child feedback to caregiving decisions. In Part 1 of the study, 33 female participants were recruited to undergo a lab-based mild stressor, the Social Evaluation Test (SET), and then in Part 2 of the study, a subset of the participants, 14 mothers, performed a Parenting Decision Making Task (PDMT) in an fMRI setting. Four dimensions of dispositional empathy based on the Interpersonal Reactivity Index were measured in all participants-Personal Distress, Empathic Concern, Perspective Taking, and Fantasy. Overall, we found that the Personal Distress and Perspective Taking were associated with greater and lesser cortisol reactivity, respectively. The four types of empathy were distinctly associated with the negative (vs. positive) child feedback activation in the brain. Personal Distress was associated with amygdala and hypothalamus activation, Empathic Concern with the left ventral striatum, ventrolateral prefrontal cortex (VLPFC), and supplemental motor area (SMA) activation, and Fantasy with the septal area, right SMA and VLPFC activation. Interestingly, hypothalamus-septal coupling during the negative feedback condition was associated with less PDMT-related cortisol reactivity. The roles of distinct forms of dispositional empathy in neural and stress responses are discussed
Multimodal Imaging Reveals Bilateral Idiopathic Multiple Retinal Pigment Epithelial Detachments: A Case Report
Background: Retinal pigment epithelial detachment (RPED) is a nonspecific finding that is common in several ocular diseases; however, cases of bilateral idiopathic multiple RPEDs are rare. Less than 50 cases have been reported to date. Bilateral multiple RPEDs are usually idiopathic and benign in nature but can infrequently be associated with various ocular and systemic diseases, including central serous chorioretinopathy (CSC). The potential role of genetic factors in this condition remains elusive. We present a case where multimodal imaging assisted in revealing the diagnosis as well as discuss the potential implications of some of the genetic findings for this patient.
Case report: A 30-year-old male presented with a chief complaint of mild, bilateral central blur of one-year duration. Health history was positive for type 2 diabetes mellitus.
Conclusion: Multimodal ophthalmic imaging is useful in ruling out various differential diagnoses in posterior segment care, as well as monitoring for progressive changes such as sensory retinal detachment and choroidal neovascularization. Bilateral idiopathic multiple RPED is a rare condition that may represent an atypical form of CSC. There is currently no preferred treatment, besides observation, as visual prognosis is typically good
Parenting and Beyond: Common Neurocircuits Underlying Parental and Altruistic Caregiving
Interpersonal relationships constitute the foundation on which human society is based. The infant–caregiver bond is the earliest and most influential of these relationships. Driven by evolutionary pressure for survival, parents feel compelled to provide care to their biological offspring. However, compassion for non-kin is also ubiquitous in human societies, motivating individuals to suppress their own self-interests to promote the well-being of non-kin members of the society. We argue that the process of early kinship-selective parental care provides the foundation for non-exclusive altruism via the activation of a general Caregiving System that regulates compassion in any of its forms. We propose a tripartite structure of this system that includes (1) the perception of need in another, (2) a caring motivational or feeling state, and (3) the delivery of a helping response to the individual in need. Findings from human and animal research point to specific neurobiological mechanisms including activation of the insula and the secretion of oxytocin that support the adaptive functioning of this Caregiving System
Heterosubtype Neutralizing Responses to Influenza A (H5N1) Viruses Are Mediated by Antibodies to Virus Haemagglutinin
Background: It is increasingly clear that influenza A infection induces cross-subtype neutralizing antibodies that may potentially confer protection against zoonotic infections. It is unclear whether this is mediated by antibodies to the neuraminidase (NA) or haemagglutinin (HA). We use pseudoviral particles (H5pp) coated with H5 haemagglutinin but not N1 neuraminidase to address this question. In this study, we investigate whether cross-neutralizing antibodies in persons unexposed to H5N1 is reactive to the H5 haemagglutinin. Methodology/Principal Findings: We measured H5-neutralization antibody titers pre- and post-vaccination using the H5N1 micro-neutralization test (MN) and H5pp tests in subjects given seasonal vaccines and in selected sera from European elderly volunteers in a H5N1 vaccine trial who had detectable pre-vaccination H5N1 MN antibody titers. We found detectable (titer ≥20) H5N1 neutralizing antibodies in a minority of pre-seasonal vaccine sera and evidence of a serological response to H5N1 in others after seasonal influenza vaccination. There was excellent correlation in the antibody titers between the H5N1 MN and H5pp tests. Similar correlations were found between MN and H5pp in the pre-vaccine sera from the cohort of H5N1 vaccine trial recipients. Conclusions/Significance: Heterosubtype neutralizing antibody to H5N1 in healthy volunteers unexposed to H5N1 is mediated by cross-reaction to the H5 haemagglutinin. Copyright: © 2009 Garcia et al.published_or_final_versio
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