Preparing Red-Green-Blue (RGB) Images from CCD Data

We present a new, and we believe arguably correct, algorithm for producing Red-Green-Blue (RBG) composites from 3-band astronomical images. Our method ensures that an object with a specified astronomical color (e.g. g-r and r-i) has a unique color in the RGB image, as opposed to the burnt-out white stars to which we are accustomed. A natural consequence of this is that we can use the same colors to code color-magnitude diagrams, providing a natural `index' to our images. We also introduce the use of an asinh stretch, which allows us to show faint objects while simultaneously preserving the structure of brighter objects in the field, such as the spiral arms of large galaxies. We believe that, in addition to their aesthetic value, our images convey far more information than do the traditional ones, and provide examples from Sloan Digital Sky Survey (SDSS) imaging, the Hubble Deep Field (HDF), and Chandra to support our claims. More examples are available at http://www.astro.princeton.edu/~rhl/PrettyPicture

The transcription factor BATF operates as an essential differentiation checkpoint in early effector CD8+ T cells

The transcription factor BATF is required for interleukin 17 (IL-17)-producing helper T cell (TH17) and follicular helper T cell (TFH) differentiation. Here, we show that BATF also has a fundamental role in regulating effector CD8+ T cell differentiation. BATF-deficient CD8+ T cells show profound defects in effector expansion and undergo proliferative and metabolic catastrophe early after antigen encounter. BATF, together with IRF4 and Jun proteins, binds to and promotes early expression of genes encoding lineage-specific transcription-factors (T-bet and Blimp-1) and cytokine receptors, while paradoxically repressing genes encoding effector molecules (IFN-γ and granzyme B). Thus, BATF amplifies TCR-dependent transcription factor expression and augments inflammatory signal propagation but restrains effector gene expression. This checkpoint prevents irreversible commitment to an effector fate until a critical threshold of downstream transcriptional activity has been achieved

Anomalously low PAH emission from low-luminosity galaxies

The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC) near and mid-infrared imaging data partially overlaps the Sloan Digital Sky Survey (SDSS), with 313 visually selected (r<17.6 mag) SDSS Main Sample galaxies in the overlap region. The 3.5 and 7.8 um properties of the galaxies are investigated in the context of their visual properties, where the IRAC [3.5] magnitude primarily measures starlight, and the [7.8] magnitude primarily measures PAH emission from the interstellar medium. As expected, we find a strong inverse correlation between [3.5]-[7.8] and visual color; galaxies red in visual colors (`red galaxies') tend to show very little dust and molecular emission (low `PAH-to-star' ratios), and galaxies blue in visual colors (`blue galaxies,' ie, star-forming galaxies) tend to show large PAH-to-star ratios. Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by dust lanes. Simple, visually inferred attenuation corrections bring the visual colors of these galaxies in line with those of face-on disks; ie, PAH emission is closely related to attenuation-corrected, optically inferred star-formation rates. Blue galaxies with anomalously low PAH-to-star ratios are all low-luminosity star-forming galaxies. There is some weak evidence in this sample that the deficiency in PAH emission for these low-luminosity galaxies may be related to emission-line metallicity.Comment: submitted to ApJ. Because of some obscure arXiv bug, the RGB figure may appear correctly only in the PDF versio

Human neutrophil clearance of bacterial pathogens triggers anti-microbial gamma delta T cell responses in early infection

Human blood Vc9/Vd2 T cells, monocytes and neutrophils share a responsiveness toward inflammatory chemokines and are rapidly recruited to sites of infection. Studying their interaction in vitro and relating these findings to in vivo observations in patients may therefore provide crucial insight into inflammatory events. Our present data demonstrate that Vc9/Vd2 T cells provide potent survival signals resulting in neutrophil activation and the release of the neutrophil chemoattractant CXCL8 (IL-8). In turn, Vc9/Vd2 T cells readily respond to neutrophils harboring phagocytosed bacteria, as evidenced by expression of CD69, interferon (IFN)-c and tumor necrosis factor (TNF)-a. This response is dependent on the ability of these bacteria to produce the microbial metabolite (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), requires cell-cell contact of Vc9/Vd2 T cells with accessory monocytes through lymphocyte function-associated antigen-1 (LFA-1), and results in a TNF-a dependent proliferation of Vc9/Vd2 T cells. The antibiotic fosmidomycin, which targets the HMB-PP biosynthesis pathway, not only has a direct antibacterial effect on most HMB-PP producing bacteria but also possesses rapid anti-inflammatory properties by inhibiting cd T cell responses in vitro. Patients with acute peritoneal-dialysis (PD)-associated bacterial peritonitis – characterized by an excessive influx of neutrophils and monocytes into the peritoneal cavity – show a selective activation of local Vc9/Vd2 T cells by HMB-PP producing but not by HMB-PP deficient bacterial pathogens. The cd T celldriven perpetuation of inflammatory responses during acute peritonitis is associated with elevated peritoneal levels of cd T cells and TNF-a and detrimental clinical outcomes in infections caused by HMB-PP positive microorganisms. Taken together, our findings indicate a direct link between invading pathogens, neutrophils, monocytes and microbe-responsive cd T cells in early infection and suggest novel diagnostic and therapeutic approaches.Martin S. Davey, Chan-Yu Lin, Gareth W. Roberts, Sinéad Heuston, Amanda C. Brown, James A. Chess, Mark A. Toleman, Cormac G.M. Gahan, Colin Hill, Tanya Parish, John D. Williams, Simon J. Davies, David W. Johnson, Nicholas Topley, Bernhard Moser and Matthias Eber

The epigenetic landscape of T cell exhaustion.

Exhausted T cells in cancer and chronic viral infection express distinctive patterns of genes, including sustained expression of programmed cell death protein 1 (PD-1). However, the regulation of gene expression in exhausted T cells is poorly understood. Here, we define the accessible chromatin landscape in exhausted CD8+ T cells and show that it is distinct from functional memory CD8+ T cells. Exhausted CD8+ T cells in humans and a mouse model of chronic viral infection acquire a state-specific epigenetic landscape organized into functional modules of enhancers. Genome editing shows that PD-1 expression is regulated in part by an exhaustion-specific enhancer that contains essential RAR, T-bet, and Sox3 motifs. Functional enhancer maps may offer targets for genome editing that alter gene expression preferentially in exhausted CD8+ T cells

Mid‐Infrared and Visible Photometry of Galaxies: Anomalously Low Polycyclic Aromatic Hydrocarbon Emission from Low‐Luminosity Galaxies

The Spitzer Space Telescope First Look Survey Infrared Array Camera (IRAC) near- and mid-infrared imaging data partially overlap the Sloan Digital Sky Survey (SDSS), with 313 visible-selected (r < 17.6 mag) SDSS main sample galaxies in the overlap region. The 3.5 and 7.8 μm properties of the galaxies are investigated in the context of their visible properties, where the IRAC [3.5] magnitude primarily measures starlight and the [7.8] magnitude primarily measures polycyclic aromatic hydrocarbon (PAH) emission from the interstellar medium. As expected, we find a strong inverse correlation between [3.5]-[7.8] and visible color; galaxies red in visible colors ("red galaxies") tend to show very little dust and molecular emission (low PAH-to-star ratios), and galaxies blue in visible colors ("blue galaxies," i.e., star-forming galaxies) tend to show large PAH-to-star ratios. Red galaxies with high PAH-to-star ratios tend to be edge-on disks reddened by dust lanes. Simple attenuation corrections inferred in the visible bring the visible colors of these galaxies in line with those of face-on disks; i.e., PAH emission is closely related to attenuation-corrected star formation rates inferred in the visible. Blue galaxies with anomalously low PAH-to-star ratios are all low-luminosity star-forming galaxies. There is some weak evidence in this sample that the deficiency in PAH emission for these low-luminosity galaxies may be related to emission-line metallicity.Astronom

How Did We Get a COVID-19 Vaccine in Less Than 1 Year?

The successful development of COVID-19 vaccines within an unprecedented short time needs to be followed by rapid vaccine uptake, in particular, in high-risk populations such as patients with cancer. It is important for the scientific research community and cancer physicians to convey the knowledge behind the COVID-19 vaccine development and contribute to build the required trust on their use