232 research outputs found
Becoming a Social Justice Educator: Emerging from the Pits of Whiteness into the Light of Love. A Response to Respect the Differences? Challenging the Common Guidelines in Social Justice Education
This paper addresses the limitations of social justice in institutional spaces and in rhetoric. I write in the form of a quest narrative to describe the lessons I learned from a brief sojourn in a temporary position in an urban teacher education program with a social justice focus and at a nonprofit organization with other social justice workers. My quest entails a retelling of encounters with Whiteness, the challenges of engaging social justice as a process that pushes beyond conversation, and the lessons I took away from my own sense-making of the contradictions in social justice work
Flared Disks and Silicate Emission in Young Brown Dwarfs
We present mid-infrared photometry of three very young brown dwarfs located
in the Ophiuchi star-forming region -- GY5, GY11 and GY310 --obtained
with the Subaru 8-meter telescope. All three sources were detected at 8.6 and
11.7m, confirming the presence of significant mid-infrared excess arising
from optically thick dusty disks. The spectral energy distributions of both
GY310 and GY11 exhibit strong evidence of flared disks; flat disks can be ruled
out for these two brown dwarfs. The data for GY5 show large scatter, and are
marginally consistent with both flared and flat configurations. Inner holes a
few substellar radii in size are indicated in all three cases (and especially
in GY11), in agreement with magnetospheric accretion models. Finally, our
9.7m flux for GY310 implies silicate emission from small grains on the
disk surface (though the data do not completely preclude larger grains with no
silicate feature). Our results demonstrate that disks around young substellar
objects are analogous to those girdling classical T Tauri stars, and exhibit a
similar range of disk geometries and dust properties.Comment: submitted to Astrophysical Journal Letter
Molecular line mapping of the giant molecular cloud associated with RCW 106 - III. Multi-molecular line mapping
We present multi-molecular line maps obtained with the Mopra Telescope
towards the southern giant molecular cloud (GMC) complex G333, associated with
the HII region RCW 106. We have characterised the GMC by decomposing the 3D
data cubes with GAUSSCLUMPS, and investigated spatial correlations among
different molecules with principal component analysis (PCA). We find no
correlation between clump size and line width, but a strong correlation between
emission luminosity and line width. PCA classifies molecules into high and low
density tracers, and reveals that HCO+ and N2H+ are anti-correlated.Comment: 24 pages, 21 figures accepted by MNRA
Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap
The disk around the Herbig Ae star HD\,169142 was imaged and resolved at 18.8
and 24.5\,m using Subaru/COMICS. We interpret the observations using a 2D
radiative transfer model and find evidence for the presence of a large gap. The
MIR images trace dust that emits at the onset of the strong rise in the
spectral energy distribution (SED) at 20\,m, therefore are very sensitive
to the location and characteristics of the inner wall of the outer disk and its
dust. We determine the location of the wall to be 23\,AU from the
star. An extra component of hot dust must exist close to the star. We find that
a hydrostatic optically thick inner disk does not produce enough flux in the
NIR and an optically thin geometrically thick component is our solution to fit
the SED. Considering the recent findings of gaps and holes in a number of
Herbig Ae/Be group I disks, we suggest that such disk structures may be common
in group I sources. Classification as group I should be considered a support
for classification as a transitional disk, though improved imaging surveys are
needed to support this speculation.Comment: 18 pages, 5 figures, accepted to Ap
Kilonova from post-merger ejecta as an optical and near-Infrared counterpart of GW170817
Recent detection of gravitational waves from a neutron star (NS) merger event GW170817 and identification of an electromagnetic counterpart provide a unique opportunity to study the physical processes in NS mergers. To derive properties of ejected material from the NS merger, we perform radiative transfer simulations of kilonova, optical and near-infrared emissions powered by radioactive decays of r-process nuclei synthesized in the merger. We find that the observed near-infrared emission lasting for >10 d is explained by 0.03 M⊙ of ejecta containing lanthanide elements. However, the blue optical component observed at the initial phases requires an ejecta component with a relatively high electron fraction (Ye). We show that both optical and near-infrared emissions are simultaneously reproduced by the ejecta with a medium Ye of ∼0.25. We suggest that a dominant component powering the emission is post-merger ejecta, which exhibits that the mass ejection after the first dynamical ejection is quite efficient. Our results indicate that NS mergers synthesize a wide range of r-process elements and strengthen the hypothesis that NS mergers are the origin of r-process elements in the Universe
Myosin Light Chain Kinase Mediates Intestinal Barrier Disruption following Burn Injury
Background: Severe burn injury results in the loss of intestinal barrier function, however, the underlying mechanism remains unclear. Myosin light chain (MLC) phosphorylation mediated by MLC kinase (MLCK) is critical to the pathophysiological regulation of intestinal barrier function. We hypothesized that the MLCK-dependent MLC phosphorylation mediates the regulation of intestinal barrier function following burn injury, and that MLCK inhibition attenuates the burn-induced intestinal barrier disfunction. Methodology/Principal Findings: Male balb/c mice were assigned randomly to either sham burn (control) or 30 % total body surface area (TBSA) full thickness burn without or with intraperitoneal injection of ML-9 (2 mg/kg), an MLCK inhibitor. In vivo intestinal permeability to fluorescein isothiocyanate (FITC)-dextran was measured. Intestinal mucosa injury was assessed histologically. Tight junction proteins ZO-1, occludin and claudin-1 was analyzed by immunofluorescent assay. Expression of MLCK and phosphorylated MLC in ileal mucosa was assessed by Western blot. Intestinal permeability was increased significantly after burn injury, which was accompanied by mucosa injury, tight junction protein alterations, and increase of both MLCK and MLC phosphorylation. Treatment with ML-9 attenuated the burn-caused increase of intestinal permeability, mucosa injury, tight junction protein alterations, and decreased MLC phosphorylation, but not MLCK expression
Blockade of interleukin-6 signaling inhibits the classic pathway and promotes an alternative pathway of macrophage activation after spinal cord injury in mice
Background Recent in vivo and in vitro studies in non-neuronal and neuronal tissues have shown that different pathways of macrophage activation result in cells with different properties. Interleukin (IL)-6 triggers the classically activated inflammatory macrophages (M1 phenotype), whereas the alternatively activated macrophages (M2 phenotype) are anti-inflammatory. The objective of this study was to clarify the effects of a temporal blockade of IL-6/IL-6 receptor (IL-6R) engagement, using an anti-mouse IL-6R monoclonal antibody (MR16-1), on macrophage activation and the inflammatory response in the acute phase after spinal cord injury (SCI) in mice. Methods MR16-1 antibodies versus isotype control antibodies or saline alone were administered immediately after thoracic SCI in mice. SC tissue repair was compared between the two groups by Luxol fast blue (LFB) staining for myelination and immunoreactivity for the neuronal markers growth-associated protein (GAP)-43 and neurofilament heavy 200 kDa (NF-H) and for locomotor function. The expression of T helper (Th)1 cytokines (interferon (IFN)-? and tumor necrosis factor-a) and Th2 cytokines (IL-4, IL-13) was determined by immunoblot analysis. The presence of M1 (inducible nitric oxide synthase (iNOS)-positive, CD16/32-positive) and M2 (arginase 1-positive, CD206-positive) macrophages was determined by immunohistology. Using flow cytometry, we also quantified IFN-? and IL-4 levels in neutrophils, microglia, and macrophages, and Mac-2 (macrophage antigen-2) and Mac-3 in M2 macrophages and microglia. Results LFB-positive spared myelin was increased in the MR16-1-treated group compared with the controls, and this increase correlated with enhanced positivity for GAP-43 or NF-H, and improved locomotor Basso Mouse Scale scores. Immunoblot analysis of the MR16-1-treated samples identified downregulation of Th1 and upregulation of Th2 cytokines. Whereas iNOS-positive, CD16/32-positive M1 macrophages were the predominant phenotype in the injured SC of non-treated control mice, MR16-1 treatment promoted arginase 1-positive, CD206-positive M2 macrophages, with preferential localization of these cells at the injury site. MR16-1 treatment suppressed the number of IFN-?-positive neutrophils, and increased the number of microglia present and their positivity for IL-4. Among the arginase 1-positive M2 macrophages, MR16-1 treatment increased positivity for Mac-2 and Mac-3, suggestive of increased phagocytic behavior. Conclusion The results suggest that temporal blockade of IL-6 signaling after SCI abrogates damaging inflammatory activity and promotes functional recovery by promoting the formation of alternatively activated M2 macrophages
CHIMPS2: Survey description and <sup>12</sup>CO emission in the Galactic Centre
Abstract The latest generation of Galactic-plane surveys is enhancing our ability to study the effects of galactic environment upon the process of star formation. We present the first data from CO Heterodyne Inner Milky Way Plane Survey 2 (CHIMPS2). CHIMPS2 is a survey that will observe the Inner Galaxy, the Central Molecular Zone (CMZ), and a section of the Outer Galaxy in 12CO, 13CO, and C18O (J = 3 → 2) emission with the Heterodyne Array Receiver Program on the James Clerk Maxwell Telescope (JCMT). The first CHIMPS2 data presented here are a first look towards the CMZ in 12CO J = 3→2 and cover −3○ ≤ ℓ ≤ 5○ and ∣∣ ≤ 05 with angular resolution of 15 arcsec, velocity resolution of 1 km s−1, and rms 0.58 K at these resolutions. Such high-resolution observations of the CMZ will be a valuable data set for future studies, whilst complementing the existing Galactic Plane surveys, such as SEDIGISM, the infrared Galactic Plane Survey, and ATLASGAL. In this paper, we discuss the survey plan, the current observations and data, as well as presenting position-position maps of the region. The position-velocity maps detect foreground spiral arms in both absorption and emission
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
- …