ABSTRACT
Spatially resolved images of debris discs are necessary to determine disc morphological properties and the scattering phase function (SPF) thatantifies the brightness of scattered light as a ...function of phase angle. Current high-contrast imaging instruments have successfully resolved several dozens of debris discs around other stars, but few studies have investigated trends in the scattered-light, resolved population of debris discs in a uniform and consistent manner. We have combined Karhunen-Loeve Image Projection (KLIP) with radiative-transfer disc forward modelling in order to obtain the highest-quality image reductions and constrain disc morphological properties of eight debris discs imaged by the Gemini Planet Imager at H-band with a consistent and uniformly applied approach. In describing the scattering properties of our models, we assume a common SPF informed from solar system dust scattering measurements and apply it to all systems. We identify a diverse range of dust density properties among the sample, including critical radius, radial width, and vertical width. We also identify radially narrow and vertically extended discs that may have resulted from substellar companion perturbations, along with a tentative positive trend in disc eccentricity with relative disc width. We also find that using a common SPF can achieve reasonable model fits for discs that are axisymmetric and asymmetric when fitting models to each side of the disc independently, suggesting that scattering behaviour from debris discs may be similar to Solar system dust.
Chimeric antigen receptor (CAR) T cell therapy has yielded unprecedented outcomes in some patients with hematological malignancies; however, inhibition by the tumor microenvironment has prevented the ...broader success of CART cell therapy. We used chronic lymphocytic leukemia (CLL) as a model to investigate the interactions between the tumor microenvironment and CART cells. CLL is characterized by an immunosuppressive microenvironment, an abundance of systemic extracellular vesicles (EVs), and a relatively lower durable response rate to CART cell therapy. In this study, we characterized plasma EVs from untreated CLL patients and identified their leukemic cell origin. CLL-derived EVs were able to induce a state of CART cell dysfunction characterized by phenotypical, functional, and transcriptional changes of exhaustion. We demonstrate that, specifically, PD-L1+ CLL-derived EVs induce CART cell exhaustion. In conclusion, we identify an important mechanism of CART cell exhaustion induced by EVs from CLL patients.
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Broad application of chimeric antigen receptor (CAR) T cell therapy is limited by T cell dysfunction, development of T cell exhaustion, and inhibition by the tumor microenvironment. Cox et al. demonstrate that leukemic-derived extracellular vesicles (EVs) interact with CART cells and induce phenotypical, functional, and transcriptional changes of T cell exhaustion.
Surrounding SN 1987A is a three-ring nebula attributed to interacting stellar winds, yet no model has successfully reproduced this system. Fortunately, the progenitor's mass-loss history can be ...reconstructed using light echoes, in which scattered light from the supernova traces the three-dimensional morphology of its circumstellar dust. In this paper, we construct and analyze the most complete map to date of the progenitor's circumstellar environment, using ground- and space-based imaging from the past 16 years. PSF-matched difference-imaging analyses of data from 1988 through 1997 reveal material between 1 and 28 lt-yr from the SN. Previously known structures, such as an inner hourglass, Napoleon's Hat, and a contact discontinuity, are probed in greater spatial detail than before. Previously unknown features are also discovered, such as a southern counterpart to Napoleon's Hat. Careful analyses of these echoes allows the reconstruction of the probable circumstellar environment, revealing a richly structured bipolar nebula. An outer, double-lobed "Peanut," which is believed to be the contact discontinuity between red supergiant and main-sequence winds, is a prolate shell extending 28 lt-yr along the poles and 11 lt-yr near the equator. Napoleon's Hat, previously believed to be an independent structure, is the waist of this Peanut, which is pinched to a radius of 6 lt-yr. Interior to this is a cylindrical hourglass, 1 lt-yr in radius and 4 lt-yr long, which connects to the Peanut by a thick equatorial disk. The nebulae are inclined 41 south and 8 east of the line of sight, slightly elliptical in cross section, and marginally offset west of the SN. From the hourglass to the large, bipolar lobes, echo fluxes suggest that the gas density drops from 1-3 to 0.03 cm super(-3), while the maximum dust-grain size increases from 60.2 to 2 km, and the silicate:carbonaceous dust ratio decreases. The nebulae have a total mass of 61.7 M sub( ). The geometry of the three rings is studied, suggesting the northern and southern rings are located 1.3 and 1.0 lt-yr from the SN, while the equatorial ring is elliptical (b/a 0.98), and spatially offset in the same direction as the hourglass.
This article evaluates a trauma-informed, mental health-law enforcement intervention model called the Greensboro Child Response Initiative (CRI). CRI is a community-coordinated response to mitigate ...the development of traumatic stress symptoms in children exposed to violence, with the goals of decreasing mental health symptoms and other negative outcomes. Results from a quasi-experimental study indicated that caregivers appreciate the quick follow-up and support by CRI advocates and police reported seeing CRI as a critical component of their responses to calls for service related to families and children. Police line-ups and training provided by CRI increased levels of empathy and awareness of child trauma. Monthly stakeholder meetings promoted an informed victim response and increased communication and networking opportunities among community providers and law enforcement. Results suggest that CRI is a promising community-based early intervention, and implications and suggestions are provided for replicability.
When a massive star explodes as a supernova, substantial amounts of radioactive elements-primarily Ni-56, Ni-57 and Ti-44 are produced. After the initial from shock heating, the light emitted by the ...supernova is due to the decay of these elements. However, after decades, the energy powering a supernova remnant comes from the shock interaction between the ejecta and the surrounding medium. The transition to this phase has hitherto not been observed: supernovae occur too infrequently in the Milky Way to provide a young example, and extragalactic supernovae are generally too faint and too small. Here we report observations that show this transition in the supernova SN 1987A in the Large Magellan Cloud. From 1994 to 200l, the ejecta faded owing to radioactive decay of Ti-44 as predicted. Then the flux started to increase, more than doubling by the end of 2009. We show that this increase is the result of heat deposited by X-rays produced as the ejecta interacts with the surrounding material. In time, the X-rays will penetrate farther into the ejects, enabling us to analyse the structure and chemistry of the vanished star.
We present new (2004 July) G750L and G140L Space Telescope Imaging Spectrograph (STIS) data of the Ha and Lya emission from supernova remnant (SNR) 1987A. With the aid of earlier data, from 1997 ...October to 2002 October, we track the local evolution of Lya emission and both the local and global evolution of Ha emission. The most recent observations allow us to directly compare the Ha and Lya emission from the same slit position and at the same epoch. Consequently, we find clear evidence that, unlike Ha, Lya is reflected from the debris by resonant scattering. In addition to emission that we can clearly attribute to the surface of the reverse shock, we also measure comparable emission, in both Ha and Lya, that appears to emerge from supernova debris interior to the surface. New observations taken through slits positioned slightly eastward and westward of a central slit show a departure from cylindrical symmetry in the Ha surface emission. Using a combination of old and new observations, we construct a light curve of the total Ha flux, F, from the reverse shock, which has increased by a factor of 64 over about 8 yr. However, due to large systematic uncertainties, we are unable to discern between the two limiting behaviors of the flux: F 8t (self-similar expansion) and F 8t super(5) (halting of the reverse shock). Such a determination is important for constraining the rate of hydrogen atoms crossing the shock, which is relevant to the question of whether the reverse shock emission will vanish in 7 yr. Future deep, low- or moderate-resolution spectra are essential for accomplishing this task.
We present results of a microlensing survey toward the Andromeda Galaxy (M 31) carried out during four observing seasons at the Isaac Newton Telescope (INT). This survey is part of the larger ...microlensing survey toward M 31 performed by the Microlensing Exploration of the Galaxy and Andromeda (MEGA) collaboration. Using a fully automated search algorithm, we identify 14 candidate microlensing events, three of which are reported here for the first time. Observations obtained at the Mayall telescope are combined with the INT data to produce composite lightcurves for these candidates. The results from the survey are compared with theoretical predictions for the number and distribution of events. These predictions are based on a Monte Carlo calculation of the detection efficiency and disk-bulge-halo models for M 31. The models provide the full phase-space distribution functions (DFs) for the lens and source populations and are motivated by dynamical and observational considerations. They include differential extinction and span a wide range of parameter space characterised primarily by the mass-to-light ratios for the disk and bulge. For most models, the observed event rate is consistent with the rate predicted for self-lensing - a MACHO halo fraction of 30% or higher can be ruled at the 95% confidence level. The event distribution does show a large near-far asymmetry hinting at a halo contribution to the microlensing signal Two candidate events are located at particularly large projected radii on the far side of the disk. These events are difficult to explain by self lensing and only somewhat easier to explain by MACHO lensing. A possibility is that one of these is due to a lens in a giant stellar stream.
We present the first M 31 candidate microlensing events from the Microlensing Exploration of the Galaxy and Andromeda (MEGA) survey. MEGA uses several telescopes to detect microlensing towards the ...nearby Andromeda galaxy, M 31, in order to establish whether massive compact objects are a significant contribution to the mass budget of the dark halo of M 31. The results presented here are based on observations with the Isaac Newton Telescope on La Palma, during the 1999/00 and 2000/01 observing seasons. In this data set, 14 variable sources consistent with microlensing have been detected, 12 of which are new and 2 have been reported previously by the POINT-AGAPE group. A preliminary analysis of the spatial and timescale distributions of the candidate events support their microlensing nature. We compare the spatial distributions of the candidate events and of long-period variable stars, assuming the chances of finding a long-period variable and a microlensing event are comparable. The spatial distribution of our candidate microlensing events is more far/near side asymmetric than expected from the detected long-period variable distribution. The current analysis is preliminary and the asymmetry not highly significant, but the spatial distribution of candidate microlenses is suggestive of the presence of a microlensing halo.
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