870 micron Imaging of a Transitional Disk in Upper Scorpius: Holdover from the Era of Giant Planet Formation?

We present 880 micron images of the transition disk around the star [PZ99] J160421.7-213028, a solar-mass star in the nearby Upper Scorpius association. With a resolution down to 0.34 arcsec, we resolve the inner hole in this disk, and via model fitting to the visibilities and spectral energy distribution we determine both the structure of the outer region and the presence of sparse dust within the cavity. The disk contains about 0.1 Jupiter masses of mm-emitting grains, with an inner disk edge of about 70 AU. The inner cavity contains a small amount of dust with a depleted surface density in a region extending from about 20-70 AU. Taking into account prior observations indicating little to no stellar accretion, the lack of a binary companion, and the presence of dust near 0.1 AU, we determine that the most likely mechanism for the formation of this inner hole is the presence of one or more giant planets.Comment: 12 pages, 7 figures. To appear in the Astrophysical Journa

Magnification as a Tool in Weak Lensing

Weak lensing surveys exploit measurements of galaxy ellipticities. These measurements are subject to errors which degrade the cosmological information that can be extracted from the surveys. Here we propose a way of using the galaxy data themselves to calibrate the measurement errors. In particular, the cosmic shear field, which causes the galaxies to appear elliptical, also changes their sizes and fluxes. Information about the sizes and fluxes of the galaxies can be added to the shape information to obtain more robust information about the cosmic shear field. The net result will be tighter constraints on cosmological parameters such as those which describe dark energy.Comment: 4 pages, 2 figure

A Herschel PACS survey of the dust and gas in Upper Scorpius disks

We present results of far-infrared photometric observations with Herschel PACS of a sample of Upper Scorpius stars, with a detection rate of previously known disk-bearing K and M stars at 70, 100, and 160 micron of 71%, 56%, and 50%, respectively. We fit power-law disk models to the spectral energy distributions of K & M stars with infrared excesses, and have found that while many disks extend in to the sublimation radius, the dust has settled to lower scale heights than in disks of the less evolved Taurus-Auriga population, and have much reduced dust masses. We also conducted Herschel PACS observations for far-infrared line emission and JCMT observations for millimeter CO lines. Among B and A stars, 0 of 5 debris disk hosts exhibit gas line emission, and among K and M stars, only 2 of 14 dusty disk hosts are detected. The OI 63 micron and CII 157 micron lines are detected toward [PZ99] J160421.7-213028 and [PBB2002] J161420.3-190648, which were found in millimeter photometry to host two of the most massive dust disks remaining in the region. Comparison of the OI line emission and 63 micron continuum to that of Taurus sources suggests the emission in the former source is dominated by the disk, while in the other there is a significant contribution from a jet. The low dust masses found by disk modeling and low number of gas line detections suggest that few stars in Upper Scorpius retain sufficient quantities of material for giant planet formation. By the age of Upper Scorpius, giant planet formation is essentially complete.Comment: 48 pages, 14 figures, accepted A&

Burden tests can be used to map causal genes for a simple metabolic trait in an exome-sequenced polyploid mutant population

Forward genetic screens are an excellent tool to assign gene function, but it is often necessary to employ map-based cloning to identify the causal genes. This can be laborious and represents a bottleneck in plant fundamental and applied research. With advances in DNA technology, it is becoming increasingly affordable to sequence large populations. Krasileva et al. (2017) exome sequenced tetraploid and hexaploid wheat ethyl methanesulfonate (EMS) mutagenized populations, primarily to facilitate reverse genetic screens. Gene redundancy allows a very high mutant load of 35–40 mutations per kilobase, and the populations of ~1500 and ~1200 lines each harbour ~22–23 missense or truncation mutations per gene. Here, we show that burden tests, a simple form of rare-variant association analysis developed for human disease genetics (Lee et al., 2014), can be used to identify causal genes in the hexaploid wheat (Triticum aestivum) cv. Cadenza mutant population, without the need for map-based cloning

Microlensing of Circumstellar Disks

We investigate the microlensing effects on a source star surrounded by a circumstellar disk, as a function of wavelength. The microlensing light curve of the system encodes the geometry and surface brightness profile of the disk. In the mid- and far-infrared, the emission of the system is dominated by the thermal emission from the cold dusty disk. For a system located at the Galactic center, we find typical magnifications to be of order 10-20% or higher, depending on the disk surface brightness profile, and the event lasts over one year. At around 20 microns, where the emission for the star and the disk are comparable, the difference in the emission areas results in a chromatic microlensing event. Finally, in the near-infrared and visible, where the emission of the star dominates, the fraction of star light directly reflected by the disk slightly modifies the light curve of the system which is no longer that of a point source. In each case, the corresponding light curve can be used to probe some of the disk properties. A fraction of 0.1% to 1% optical microlensing events are expected to be associated with circumstellar disk systems. We show that the lensing signal of the disk can be detected with sparse follow-up observations of the next generation space telescopes. While direct imaging studies of circumstellar disks are limited to the solar neighborhood, this microlensing technique can probe very distant disk systems living in various environments and has the potential to reveal a larger diversity of circumstellar disks.Comment: 9 pages, 7 figures. Accepted for publication in Ap

Academics' Experiences of a Respite From Work: Effects of Self-Critical Perfectionism and Perseverative Cognition on Postrespite Well-Being

This longitudinal study examined relations between personality and cognitive vulnerabilities and the outcomes of a respite from work. A sample of 77 academic employees responded to week-level measures of affective well-being before, during, and on 2 occasions after an Easter respite. When academics were classified as being either high or low in a self-critical form of perfectionism (doubts about actions), a divergent pattern of respite to postrespite effects was revealed. Specifically, during the respite, the 2 groups of academics experienced similar levels of well-being. However, during postrespite working weeks, the more perfectionistic academics reported significantly higher levels of fatigue, emotional exhaustion, and anxiety. The greater deterioration in well-being experienced by perfectionist academics when first returning to work was mediated by their tendency for perseverative cognition (i.e., worry and rumination) about work during the respite itself. These findings support the view that the self-critical perfectionist vulnerability is activated by direct exposure to achievement-related stressors and manifested through perseverative modes of thinking