A Fast Approximate Approach to Microlensing Survey Analysis

Microlensing can be used to discover exoplanets of a wide range of masses with orbits beyond ~ 1 AU, and even free-floating planets. The WFIRST mission will use microlensing to discover approximately 1600 planets by monitoring ~100 million stars to find ~50000 microlensing events. Modelling each microlensing event, especially the ones involving two or more lenses, is typically complicated and time-consuming, and analyzing thousands of WFIRST microlensing events is possibly infeasible using current methods. Here, we present an algorithm that is able to rapidly evaluate thousands of simulated WFIRST binary-lens microlensing light curves, returning an estimate for the physical parameters of the lens systems. We find that this algorithm can recover projected separations between the planet and the star very well for low-mass-ratio events, and can also estimate mass ratios within an order of magnitude for events with wide and close caustic topologies.Comment: 18 pages, 14 figures, Submitted to AAS journal

Robot-assisted measurement for hydrologic understanding in data sparse regions

This article describes the field application of small, low-cost robots for remote surface data collection and an automated workflow to support water balance computations and hydrologic understanding where water availability data is sparse. Current elevation measurement approaches, such as manual surveying and LiDAR, are costly and infrequent, leading to potential inefficiencies for quantifying the dynamic hydrologic storage capacity of the land surface over large areas. Experiments to evaluate a team of two different robots, including an unmanned aerial vehicle (UAV) and an unmanned surface vehicle (USV), to collect hydrologic surface data utilizing sonar and visual sensors were conducted at three different field sites within the Arkavathy Basin river network located near Bangalore in Karnataka, South India. Visual sensors were used on the UAV to capture high resolution imagery for topographic characterization, and sonar sensors were deployed on the USV to capture bathymetric readings; the data streams were fused in an automated workflow to determine the storage capacity of agricultural reservoirs (also known as “tanks”) at the three field sites. This study suggests: (i) this robot-assisted methodology is low-cost and suitable for novice users, and (ii) storage capacity data collected at previously unmapped locations revealed strong power-type relationships between surface area, stage, and storage volume, which can be incorporated into modeling of landscape-scale hydrology. This methodology is of importance to water researchers and practitioners because it produces local, high-resolution representations of bathymetry and topography and enables water balance computations at small-watershed scales, which offer insight into the present-day dynamics of a strongly human impacted watershed

Classifying High-cadence Microlensing Light Curves I; Defining Features

Microlensing is a powerful tool for discovering cold exoplanets, and the The Roman Space Telescope microlensing survey will discover over 1000 such planets. Rapid, automated classification of Roman's microlensing events can be used to prioritize follow-up observations of the most interesting events. Machine learning is now often used for classification problems in astronomy, but the success of such algorithms can rely on the definition of appropriate features that capture essential elements of the observations that can map to parameters of interest. In this paper, we introduce tools that we have developed to capture features in simulated Roman light curves of different types of microlensing events, and evaluate their effectiveness in classifying microlensing light curves. These features are quantified as parameters that can be used to decide the likelihood that a given light curve is due to a specific type of microlensing event. This method leaves us with a list of parameters that describe features like the smoothness of the peak, symmetry, the number of peaks, and width and height of small deviations from the main peak. This will allow us to quickly analyze a set of microlensing light curves and later use the resulting parameters as input to machine learning algorithms to classify the events.Comment: 29 Pages, 30 Figures, 3 Tables, Accepted to the Astronomical Journa

Successes and Failures of Hospital Ethics Committees: A National Survey of Ethics Committee Chairs

In 1992, the Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) passed a mandate that all its approved hospitals put in place a means for addressing ethical concerns. Although the particular process the hospital uses to address such concerns—ethics consultant, ethics forum, ethics committee—may vary, the hospital or healthcare ethics committee (HEC) is used most often. In a companion study to that reported here, we found that in 1998 over 90% of U.S. hospitals had ethics committees, compared to just 1% in 1983, and that many have some and a few have sweeping clinical powers in hospitals

A process‐based approach to attribution of historical streamflow decline in a data‐scarce and human‐dominated watershed

Human activities have resulted in rapid hydrological change around the world, in many cases producing shifts in the dominant hydrological processes, confounding predictions, and complicating effective management and planning. Identifying and characterizing such changes in hydrological processes is therefore a globally relevant problem, one that is particularly challenging in sparsely monitored environments. We develop a novel, process‐based approach for attribution of hydrological change in such scenarios, and apply the approach to the TG Halli watershed outside Bangalore, India, where streamflow has declined considerably over the last 50 years. The approach consists of (1) employing a range of field instrumentation and experiments to identify contemporary streamflow generation mechanisms, (2) using these observations to constrain our understanding and generate hypotheses pertaining to historical changes, and (3) evaluating these hypotheses with a range of evidence including proxies for historical hydrological processes. The body of evidence in the TG Halli watershed indicates the historical presence and subsequent loss of a shallow groundwater table that previously discharged to the stream, meaning that groundwater depletion is the most likely driver of streamflow decline. These findings present a viable path towards improved predictions of future water resources and sustainable water management within the watershed. Our process‐based approach to attribution has the potential to improve understanding of human‐driven hydrologic change in regions with poor monitoring of hydrologic systems

Severe PATCHED1 deficiency in cancer-prone Gorlin patient cells results in intrinsic radiosensitivity

PURPOSE: Gorlin syndrome (or basal-cell nevus syndrome) is a cancer-prone genetic disease in which hypersusceptibility to secondary cancer and tissue reaction after radiation therapy is debated, as is increased radiosensitivity at cellular level. Gorlin syndrome results from heterozygous mutations in the PTCH1 gene for 60% of patients, and we therefore aimed to highlight correlations between intrinsic radiosensitivity and PTCH1 gene expression in fibroblasts from adult patients with Gorlin syndrome. METHODS AND MATERIALS: The radiosensitivity of fibroblasts from 6 patients with Gorlin syndrome was determined by cell-survival assay after high (0.5-3.5 Gy) and low (50-250 mGy) γ-ray doses. PTCH1 and DNA damage response gene expression was characterized by real-time polymerase chain reaction and Western blotting. DNA damage and repair were investigated by γH2AX and 53BP1 foci assay. PTCH1 knockdown was performed in cells from healthy donors by using stable RNA interference. Gorlin cells were genotyped by 2 complementary sequencing methods. RESULTS: Only cells from patients with Gorlin syndrome who presented severe deficiency in PATCHED1 protein exhibited a significant increase in cellular radiosensitivity, affecting cell responses to both high and low radiation doses. For 2 of the radiosensitive cell strains, heterozygous mutations in the 5' end of PTCH1 gene explain PATCHED1 protein deficiency. In all sensitive cells, DNA damage response pathways (ATM, CHK2, and P53 levels and activation by phosphorylation) were deregulated after irradiation, whereas DSB repair recognition was unimpaired. Furthermore, normal cells with RNA interference-mediated PTCH1 deficiency showed reduced survival after irradiation, directly linking this gene to high- and low-dose radiosensitivity. CONCLUSIONS: In the present study, we show an inverse correlation between PTCH1 expression level and cellular radiosensitivity, suggesting an explanation for the conflicting results previously reported for Gorlin syndrome and possibly providing a basis for prognostic screens for radiosensitive patients with Gorlin syndrome and PTCH1 mutations

Spatial-Temporal Modeling of Neighborhood Sociodemographic Characteristics and Food Stores

The literature on food stores, neighborhood poverty, and race/ethnicity is mixed and lacks methods of accounting for complex spatial and temporal clustering of food resources. We used quarterly data on supermarket and convenience store locations from Nielsen TDLinx (Nielsen Holdings N.V., New York, New York) spanning 7 years (2006–2012) and census tract-based neighborhood sociodemographic data from the American Community Survey (2006–2010) to assess associations between neighborhood sociodemographic characteristics and food store distributions in the Metropolitan Statistical Areas (MSAs) of 4 US cities (Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and San Francisco, California). We fitted a space-time Poisson regression model that accounted for the complex spatial-temporal correlation structure of store locations by introducing space-time random effects in an intrinsic conditionally autoregressive model within a Bayesian framework. After accounting for census tract–level area, population, their interaction, and spatial and temporal variability, census tract poverty was significantly and positively associated with increasing expected numbers of supermarkets among tracts in all 4 MSAs. A similar positive association was observed for convenience stores in Birmingham, Minneapolis, and San Francisco; in Chicago, a positive association was observed only for predominantly white and predominantly black tracts. Our findings suggest a positive association between greater numbers of food stores and higher neighborhood poverty, with implications for policy approaches related to food store access by neighborhood poverty

Transiting Exoplanet Yields for the Roman Galactic Bulge Time Domain Survey Predicted from Pixel-Level Simulations

The Nancy Grace Roman Space Telescope (Roman) is NASA's next astrophysics flagship mission, expected to launch in late 2026. As one of Roman's core community science surveys, the Galactic Bulge Time Domain Survey (GBTDS) will collect photometric and astrometric data for over 100 million stars in the Galactic bulge to search for microlensing planets. To assess the potential with which Roman can detect exoplanets via transit, we developed and conducted pixel-level simulations of transiting planets in the GBTDS. From these simulations, we predict that Roman will find between $\sim$60,000 and $\sim$200,000 transiting planets, over an order of magnitude more planets than are currently known. While the majority of these planets will be giants ($R_p>4R_\oplus$) on close-in orbits ($a<0.3$ au), the yield also includes between $\sim$7,000 and $\sim$12,000 small planets ($R_p<4 R_\oplus$). The yield for small planets depends sensitively on the observing cadence and season duration, with variations on the order of $\sim$10-20% for modest changes in either parameter, but is generally insensitive to the trade between surveyed area and cadence given constant slew/settle times. These predictions depend sensitively on the Milky Way's metallicity distribution function, highlighting an opportunity to significantly advance our understanding of exoplanet demographics, particularly across stellar populations and Galactic environments.Comment: Accepted to ApJS; 64 pages, 18 figure