W.M. Keck Science Center

Abstract We present constraints on the physical properties (including stellar mass, age, and star formation rate) of 207 6 ≲ z ≲ 8 galaxy candidates from the Reionization Lensing Cluster Survey (RELICS) and Spitzer-RELICS surveys. We measure photometry using T-PHOT and perform spectral energy distribution fitting using EAzY and BAGPIPES. Of the 207 candidates for which we could successfully measure (or place limits on) Spitzer fluxes, 23 were demoted to likely z < 4. Among the high-z candidates, we find intrinsic stellar masses between 1 × 106 M ⊙ and 4 × 109 M ⊙, and rest-frame UV absolute magnitudes between −22.6 and −14.5 mag. While our sample is mostly comprised of L m UV / L m UV * < 1 galaxies, it extends to L m UV / L m UV * ∼ 2 . Our sample spans ∼4 orders of magnitude in stellar mass and star formation rates, and exhibits ages that range from maximally young to maximally old. We highlight 11 z ≥ 6.5 galaxies with detections in Spitzer/IRAC imaging, several of which show evidence for some combination of evolved stellar populations, large contributions of nebular emission lines, and/or dust. Among these is PLCKG287+32-2013, one of the brightest z ∼ 7 candidates known (AB mag 24.9 at 1.6 μm) with a Spitzer 3.6 μm flux excess suggesting strong [O iii] + H-β emission (∼1000 Å rest-frame equivalent width). We discuss the possible uses and limits of our sample and present a public catalog of Hubble + Spitzer photometry along with physical property estimates for all objects in the sample. Because of their apparent brightnesses, high redshifts, and variety of stellar populations, these objects are excellent targets for follow-up with the James Webb Space Telescope.

Recently, researchers have found time cells in the hippocampus that appear to contain information about the timing of past events. Some researchers have argued that time cells are taking a Laplace transform of their input in order to reconstruct the past stimulus. We argue that stimulus prediction, not stimulus reconstruction or redundancy reduction, is in better agreement with observed responses of time cells. In the process, we introduce new analyses of nonlinear, continuous-time reservoirs that model these time cells.

As the ortholog of human SR protein kinase 1 in fission yeast Schizosaccharomyces pombe, Dsk1 specifically phosphorylates SR proteins (serine/arginine-rich proteins) and promotes splicing of nonconsensus introns. The SRPK (SR protein-specific kinase) family performs highly conserved functions in eukaryotic cells including cell proliferation, differentiation, development, and apoptosis. Although Dsk1 was originally identified as a mitotic regulator, its specific targets involved in cell cycle have yet been unexplored. In this study, using a phosphoproteomics approach, we examined differential protein phosphorylation between wild-type cells and dsk1-deletion mutants. We found reduced phosphorylation of 149 peptides corresponding to 133 proteins in the dsk1-null cells. These proteins are involved in various cellular processes, including cytoskeleton organization and signal transduction, and specifically enriched in multiple steps of cell cycle control. Further, targeted MS analyses and in vitro biochemical assays established Cdr2 protein kinase and kinesin motor Klp9 as novel substrates of Dsk1, which function in cell size control for mitotic entry and in chromosome segregation for mitotic exit, respectively. The phosphoprotein networks mediated by Dsk1 reveal, for the first time, the molecular links connecting Dsk1 to mitotic phase transition, sister-chromatid segregation, and cytokinesis, providing further evidence of Dsk1's diverse influence on cell cycle progression and regulation.

Abstract Here we present new red sequence overdensity measurements for 77 fields in the high-z Clusters Occupied by Bent Radio AGN (COBRA) survey, based on r- and i-band imaging taken with the Lowell Observatory’s Discovery Channel Telescope. We observe 38 COBRA fields in the r-band and 90 COBRA fields in the i-band. By combining the r- and i-band photometry with our 3.6 and 4.5 μm Spitzer IRAC observations, we identify 39 red sequence cluster candidates that host a strong overdensity of galaxies when measuring the excess of red sequence galaxies relative to a background field. We initially treat the radio host as the cluster center and then determine a new cluster center based on the surface density of red sequence sources. Using our color selection, we identify which COBRA cluster candidates have strong red sequence populations. By removing foreground and background contaminants, we more securely determine which fields include cluster candidates with a higher significance than our single-band observations. Additionally, of the 77 fields we analyze with a redshift estimate, 26 include newly estimated photometric redshifts.

Faszination Forschung: Die Suche nach Leben Auf der Erde existieren Lebewesen, oder zumindest ihre chemischen Spuren, an allen erdenklichen Orten – selbst in den tiefsten Zonen der Meere, in Gesteinen, im Inneren von Vulkanen, im Polareis und in hoheren Luftschichten. Den Ursprung des Lebens zu finden ist allerdings keine leichte Aufgabe, da einfach gebaute und bereits fruh in der Erdgeschichte existierende Organismen (bis auf wenige Ausnahmen) keine Fossilien hinterliesen. Auf dem Mars, so hoffen Wissenschaftler, konnte das anders sein. Seit Jahrtausenden fasziniert der Rote Planet die Menschen, seit Erfindung des Teleskops insbesondere Wissenschaftler und Science-Fiction-Autoren. Der Mars ist ein kalter Planet, dessen Geologie sich uber mehrere Milliarden Jahre hinweg kaum verandert hat, wodurch mogliche Hinweise auf Leben erhalten geblieben sein konnten. Im spaten 19. Jahrhundert waren auch bedeutende Astronomen der festen Uberzeugung, dass es auf dem Mars Leben gibt. Sie beriefen sich dabei auf Beobachtungen, die sie mithilfe von Teleskopen gemacht hatten – sich mit den Jahreszeiten verandernde Eiskappen an den Polen, dunkle Regionen, von denen man vermutete, es handele sich um Wasser, sowie lineare Strukturen, die man fur Kanale hielt.

Faszination Forschung: Auf den Spuren eines Dinosauriers „Man ist, was man isst – und das gilt auch fur die Zahne“ ist eine Abwandlung einer gelaufigen Redewendung zu den in unserem Korper ablaufenden chemischen Prozessen. Eines der bedeutendsten Elemente in Organismen ist Sauerstoff (O), der unter anderem ein Bestandteil des Wassermolekuls (\(\mathrm{H_{2}O}\)) ist. Sauerstoff kommt in der Natur in zwei naturlichen Varianten vor, die man als Isotope bezeichnet. Isotope besitzen zwar weitgehend dieselben chemischen Eigenschaften, sie unterscheiden sich jedoch in ihrer Masse, da ihre Atomkerne eine unterschiedliche Zahl an Neutronen enthalten. Beide Sauerstoffisotope werden Bestandteile der Korper von Tieren, wenn diese Wasser trinken oder es mit der Nahrung aufnehmen.