Systematic Errors in Future Weak Lensing Surveys: Requirements and Prospects for Self-Calibration

We study the impact of systematic errors on planned weak lensing surveys and compute the requirements on their contributions so that they are not a dominant source of the cosmological parameter error budget. The generic types of error we consider are multiplicative and additive errors in measurements of shear, as well as photometric redshift errors. In general, more powerful surveys have stronger systematic requirements. For example, for a SNAP-type survey the multiplicative error in shear needs to be smaller than 1%(fsky/0.025)^{-1/2} of the mean shear in any given redshift bin, while the centroids of photometric redshift bins need to be known to better than 0.003(fsky/0.025)^{-1/2}. With about a factor of two degradation in cosmological parameter errors, future surveys can enter a self-calibration regime, where the mean systematic biases are self-consistently determined from the survey and only higher-order moments of the systematics contribute. Interestingly, once the power spectrum measurements are combined with the bispectrum, the self-calibration regime in the variation of the equation of state of dark energy w_a is attained with only a 20-30% error degradation.Comment: 20 pages, 9 figures, to be submitted to MNRAS. Comments are welcom

The biochemical, physiological, and metabolic evaluation of human subjects in a life support systems evaluator and on a liquid food diet Final report, 12 Jun. 1964 - 23 Feb. 1965

Biochemical, physiological, and metabolic analysis of subjects in life support system on liquid food diets during space environment simulatio

Spontaneously Localized Photonic Modes Due to Disorder in the Dielectric Constant

We present the first experimental evidence for the existence of strongly localized photonic modes due to random two dimensional fluctuations in the dielectric constant. In one direction, the modes are trapped by ordered Bragg reflecting mirrors of a planar, one wavelength long, microcavity. In the cavity plane, they are localized by disorder, which is due to randomness in the position, composition and sizes of quantum dots located in the anti-node of the cavity. We extend the theory of disorder induced strong localization of electron states to optical modes and obtain quantitative agreement with the main experimental observations.Comment: 6 page

Galaxy Selection and Clustering and Lyman alpha Absorber Identification

The effects of galaxy selection on our ability to constrain the nature of weak Ly\alpha absorbers at low redshift are explored. Current observations indicate the existence of a population of gas-rich, low surface brightness (LSB) galaxies, and these galaxies may have large cross sections for Ly\alpha absorption. Absorption arising in LSB galaxies may be attributed to HSB galaxies at larger impact parameters from quasar lines of sight, so that the observed absorption cross sections of galaxies may seem unreasonably large. Thus it is not possible to rule out scenarios where LSB galaxies make substantial contributions to Ly\alpha absorption using direct observations. Less direct tests, where observational selection effects are taken into account using simulations, should make it possible to determine the nature of Ly\alpha absorbers by observing a sample of ~100 galaxies around quasar lines of sight with well-defined selection criteria. Such tests, which involve comparing simulated and observed plots of the unidentified absorber fractions and absorbing galaxy fractions versus impact parameter, can distinguish between scenarios where absorbers arise in particular galaxies and those where absorbers arise in gas tracing the large scale galaxy distribution. Care must be taken to minimize selection effects even when using these tests. Results from such tests are likely to depend upon the limiting neutral hydrogen column density. While not enough data are currently available to make a strong conclusion about the nature of moderately weak absorbers, evidence is seen that such absorbers arise in gas that is around or between galaxies that are often not detected in surveys.Comment: 15 pages, 10 figures, accepted to the Astrophysical Journa

Effect of in-plane magnetic field on the photoluminescence spectrum of modulation-doped quantum wells and heterojunctions

The photoluminescence (PL) spectrum of modulation-doped GaAs/AlGaAs quantum wells (MDQW) and heterojunctions (HJ) is studied under a magnetic field ($B_{\|}$) applied parallel to the two-dimensional electron gas (2DEG) layer. The effect of $B_{\|}$ strongly depends on the electron-hole separation ($d_{eh}$), and we revealed remarkable $B_{\|}$-induced modifications of the PL spectra in both types of heterostructures. A model considering the direct optical transitions between the conduction and valence subband that are shifted in k-space under $B_{\|}$, accounts qualitatively for the observed spectral modifications. In the HJs, the PL intensity of the bulk excitons is strongly reduced relatively to that of the 2DEG with increasing $B_{\|}$. This means that the distance between the photoholes and the 2DEG decreases with increased $B_{\|}$, and that free holes are responsible for the hole-2DEG PL.Comment: 6pages, 5figure

Overrating Bruins, Underrating Badgers: Media, Bias, and College Basketball

Why are some teams perennial darlings of sports journalists while other talented squads get overlooked? Each week during the NCAA basketball season, the Associated Press releases a ranked poll of the top 25 teams. By comparing the preseason and postseason rankings, we construct a measure of how much sports journalists who respond to the poll overrate (or underrate) college teams relative to their actual performance. Using this metric for the 115 NCAA schools that have appeared at least once in the opening or final AP poll in the last 25 years, we examine a range of institutional characteristics that may predict overrating or underrating by members of the sports media. A multilevel analysis reveals that recent performance in the NCAA tournament and the perceived quality of the most recent recruiting class are the strongest predictors of being consistently overrated. While no institutional characteristics had direct effects, the effect of tournament performance on overrating is greater for teams that have historically had fewer coaches and compete in a “power” conference, and for national research institutions with larger student bodies. Our findings have implications for understanding how complex decisions are made within a conservative social institution (the media) and suggest that some schools may receive advantages in media exposure and financial opportunity

Influence of Early Stress on Social Abilities and Serotonergic Functions across Generations in Mice

Exposure to adverse environments during early development is a known risk factor for several psychiatric conditions including antisocial behavior and personality disorders. Here, we induced social anxiety and altered social recognition memory in adult mice using unpredictable maternal separation and maternal stress during early postnatal life. We show that these social defects are not only pronounced in the animals directly subjected to stress, but are also transmitted to their offspring across two generations. The defects are associated with impaired serotonergic signaling, in particular, reduced 5HT1A receptor expression in the dorsal raphe nucleus, and increased serotonin level in a dorsal raphe projection area. These findings underscore the susceptibility of social behaviors and serotonergic pathways to early stress, and the persistence of their perturbation across generations

The Ingram Vessel 38CT204: Intensive Survey & Excavation of an Upland Rivercraft at Cheraw, South Carolina

In 1993 and 1994 the Underwater Archaeology Division of the South Carolina Institute of Archaeology and Anthropology conducted an intensive survey of the remains of a small, wooden hulled craft in the Great Pee Dee River near Cheraw, South Carolina. The project was sponsored in part by the Cheraw Historical Society and partially funded by a grant from the South Carolina Humanities Council. The Ingram Vessel (38CT204), named after its discoverer Miller Ingram, lay overturned and largely buried beneath the river sediments and protected by a large mushroom-shaped rock just upstream of the site. The site was partially excavated and the hull remains mapped in situ. The investigation revealed a shallow draught, keeled vessel, built entirely of Southern Yellow Pine. The site is tentatively dated to the late 18th-early 19th century. Overall dimensions are estimated to have been approximately 15.5m (50ft, l0 in) in length, with a maximum beam of 4.6m (15ft, lin). This report details the research on the site and places the vessel within a regional maritime historical context. The vessel is, to date, the only ship-built hull excavated in an uplands context near the head of navigation of a South Carolina river.https://scholarcommons.sc.edu/archanth_books/1198/thumbnail.jp

A search for rapidly pulsating hot subdwarf stars in the GALEX survey

NASA's Galaxy Evolution Explorer (GALEX) provided near- and far-UV observations for approximately 77 percent of the sky over a ten-year period; however, the data reduction pipeline initially only released single NUV and FUV images to the community. The recently released Python module gPhoton changes this, allowing calibrated time-series aperture photometry to be extracted easily from the raw GALEX data set. Here we use gPhoton to generate light curves for all hot subdwarf B (sdB) stars that were observed by GALEX, with the intention of identifying short-period, p-mode pulsations. We find that the spacecraft's short visit durations, uneven gaps between visits, and dither pattern make the detection of hot subdwarf pulsations difficult. Nonetheless, we detect UV variations in four previously known pulsating targets and report their UV pulsation amplitudes and frequencies. Additionally, we find that several other sdB targets not previously known to vary show promising signals in their periodograms. Using optical follow-up photometry with the Skynet Robotic Telescope Network, we confirm p-mode pulsations in one of these targets, LAMOST J082517.99+113106.3, and report it as the most recent addition to the sdBVr class of variable stars.Comment: 11 Pages, 8 Figures, Accepted for publication in the Astrophysical Journa