Searching for Exoplanets Using Artificial Intelligence

In the last decade, over a million stars were monitored to detect transiting planets. Manual interpretation of potential exoplanet candidates is labor intensive and subject to human error, the results of which are difficult to quantify. Here we present a new method of detecting exoplanet candidates in large planetary search projects which, unlike current methods uses a neural network. Neural networks, also called "deep learning" or "deep nets" are designed to give a computer perception into a specific problem by training it to recognize patterns. Unlike past transit detection algorithms deep nets learn to recognize planet features instead of relying on hand-coded metrics that humans perceive as the most representative. Our convolutional neural network is capable of detecting Earth-like exoplanets in noisy time-series data with a greater accuracy than a least-squares method. Deep nets are highly generalizable allowing data to be evaluated from different time series after interpolation without compromising performance. As validated by our deep net analysis of Kepler light curves, we detect periodic transits consistent with the true period without any model fitting. Our study indicates that machine learning will facilitate the characterization of exoplanets in future analysis of large astronomy data sets.Comment: Accepted, 16 Pages, 14 Figures, https://github.com/pearsonkyle/Exoplanet-Artificial-Intelligenc

Spatial patterns of habitat use by white clawed crayfish (Austropotamobius pallipes) on the River Wansbeck

The white clawed crayfish (Austropotamobius pallipes) is a freshwater crustacean at imminent risk of extinction, largely due to the introduction of American signal crayfish (Pacifastacus leniusculus) to Britain. With the purpose of determining how white clawed crayfish respond to habitat and spatial variables, this study correlated white clawed crayfish distribution over a 35 km length of the River Wansbeck, Northumberland, to physical variables at three-spatial scales. White clawed crayfish were present throughout the study area at an average density of 5.3 individuals per square metre. The realised niche of white clawed crayfish was very broad; the only available areas crayfish could not make use of were those with microhabitat scale D50 smaller than 8 mm. Within their wide realised niche, crayfish showed significant responses to habitat. The strongest response was to grain size, with crayfish preferentially selecting cobbles as refuges. Distance downstream and lateral distance did not influence distribution or density of white clawed crayfish but crayfish were more abundant in the upstream half of the study area, reflecting the higher availability of favourable habitat in low order streams. Patchiness in distribution was only evident at the sub-metre scale, suggesting crayfish are only directly responding to microhabitat scale heterogeneity. Habitat based conservation actions should be conducted at this scale. However, habitat variables operating at the kilometre section and site scale (100 m) influenced the suitability of microhabitats. The abundant, dense population of white clawed crayfish on the River Wansbeck makes it a site of international importance. It is therefore recommended for designation as a Special Area of Conservation

Effects of agricultural intensification on the ecology of upland stream invertebrate communities

Agricultural land use is a leading cause of habitat degradation and biodiversity loss in streams. Understanding the mechanisms by which land use change affects stream ecosystems is essential for their effective management. Despite this, the consequences of agricultural intensification for community composition and ecosystem functioning in streams remain poorly resolved. Using national-scale monitoring data and new field data from upland streams in South Wales, this study investigated the effects of pastoral intensification on the community composition, functional diversity and feeding interactions of stream macroinvertebrates. A combination of analytical tools were used, including propensity modelling, ecological traits, stable isotopes and Next Generation DNA sequencing to quantify diet. Taxonomic and functional diversity had non-linear relationships with pastoral intensity, declining beyond a threshold of 4 mg L-1 nitrate and 8% fine sediment cover. This decline occurred as a non-random loss of species possessing specific traits, including large body size and lack of resistance forms. Although monitoring data showed that at a UK-wide scale pastoral agriculture (cf. other land uses) had a positive effect on richness and sensitive species representation, the threshold intensity at which effects become negative is exceeded in many locations within the U.K. and globally. Invertebrates that feed by grazing algae were particularly vulnerable to agricultural stressors. Combined with changes in the availability and quality of basal resources with pastoral intensification, this decline in grazer representation resulted in invertebrate communities becoming increasingly reliant on detrital resources. Further, there was indication that methane-derived carbon contributed to the food web in high intensity sites, which has not previously been observed in upland streams. Although only relatively minor changes were observed in predator-prey interactions across the intensity gradient, there was a suggestion of simplification of the food web in high intensity sites. Together these changes could radically alter ecosystem properties such as secondary production, nutrient processing and resilience. Overall, the results highlight the management priorities of reducing fine sediment and nutrient inputs to agricultural streams. The identification of a threshold at which agricultural effects become deleterious will assist in guiding mitigation efforts. Further work is required to determine the generality of this threshold across stream ecosystems

Alejandro Sánchez Alvarado: Bootstrapping flatworms into the molecular age

Sánchez Alvarado studies tissue regeneration in planarians

XO-2b: a hot Jupiter with a variable host star that potentially affects its measured transit depth

The transiting hot Jupiter XO-2b is an ideal target for multi-object photometry and spectroscopy as it has a relatively bright ($V$-mag = 11.25) K0V host star (XO-2N) and a large planet-to-star contrast ratio (R$_{p}$/R$_{s}\approx0.015$). It also has a nearby (31.21") binary stellar companion (XO-2S) of nearly the same brightness ($V$-mag = 11.20) and spectral type (G9V), allowing for the characterization and removal of shared systematic errors (e.g., airmass brightness variations). We have therefore conducted a multiyear (2012--2015) study of XO-2b with the University of Arizona's 61" (1.55~m) Kuiper Telescope and Mont4k CCD in the Bessel U and Harris B photometric passbands to measure its Rayleigh scattering slope to place upper limits on the pressure-dependent radius at, e.g., 10~bar. Such measurements are needed to constrain its derived molecular abundances from primary transit observations. We have also been monitoring XO-2N since the 2013--2014 winter season with Tennessee State University's Celestron-14 (0.36~m) automated imaging telescope to investigate stellar variability, which could affect XO-2b's transit depth. Our observations indicate that XO-2N is variable, potentially due to {cool star} spots, {with a peak-to-peak amplitude of $0.0049 \pm 0.0007$~R-mag and a period of $29.89 \pm 0.16$~days for the 2013--2014 observing season and a peak-to-peak amplitude of $0.0035 \pm 0.0007$~R-mag and $27.34 \pm 0.21$~day period for the 2014--2015 observing season. Because of} the likely influence of XO-2N's variability on the derivation of XO-2b's transit depth, we cannot bin multiple nights of data to decrease our uncertainties, preventing us from constraining its gas abundances. This study demonstrates that long-term monitoring programs of exoplanet host stars are crucial for understanding host star variability.Comment: published in ApJ, 9 pages, 11 figures, 3 tables; updated figures with more ground-based monitoring, added more citations to previous work

Identification of a critical sulfation in chondroitin that inhibits axonal regeneration.

The failure of mammalian CNS neurons to regenerate their axons derives from a combination of intrinsic deficits and extrinsic factors. Following injury, chondroitin sulfate proteoglycans (CSPGs) within the glial scar inhibit axonal regeneration, an action mediated by the sulfated glycosaminoglycan (GAG) chains of CSPGs, especially those with 4-sulfated (4S) sugars. Arylsulfatase B (ARSB) selectively cleaves 4S groups from the non-reducing ends of GAG chains without disrupting other, growth-permissive motifs. We demonstrate that ARSB is effective in reducing the inhibitory actions of CSPGs both in in vitro models of the glial scar and after optic nerve crush (ONC) in adult mice. ARSB is clinically approved for replacement therapy in patients with mucopolysaccharidosis VI and therefore represents an attractive candidate for translation to the human CNS

Safety of dietary camelina oil supplementation in healthy, adult dogs

This study aimed to determine whether camelina oil is safe for use in canine diets, using canola oil and flax oil as controls, as they are similar and generally regarded as safe (GRAS) for canine diets. A total of thirty privately-owned adult dogs of various breeds (17 females; 13 males), with an average age of 7.2 ± 3.1 years (mean ± SD) and a body weight (BW) of 27.4 ± 14.0 kg were used. After a 4-week wash-in period using sunflower oil and kibble, the dogs were blocked by breed, age, and size and were randomly allocated to one of three treatment oils (camelina (CAM), flax (FLX), or canola (OLA)) at a level of 8.2 g oil/100 g total dietary intake. Body condition score (BCS), BW, food intake (FI), and hematological and select biochemical parameters were measured at various timepoints over a 16-week feeding period. All of the data were analyzed with ANOVA using the PROC GLIMMIX of SAS. No biologically significant differences were seen between the treatment groups in terms of BW, BCS, FI, and hematological and biochemical results. Statistically significant differences noted among some serum biochemical results were considered small and were due to normal biological variation. These results support the conclusion that camelina oil is safe for use in canine nutrition

Resolving large-scale pressures on species and ecosystems: propensity modelling identifies agricultural effects on streams

1. Although agriculture is amongst the world's most widespread land uses, studies of its effects on stream ecosystems are often limited in spatial extent. National monitoring data could extend spatial coverage and increase statistical power, but present analytical challenges where covarying environmental variables confound relationships of interest. 2. Propensity modelling is used widely outside ecology to control for confounding variables in observational data. Here, monitoring data from over 3000 English and Welsh river reaches are used to assess the effects of intensive agricultural land cover (arable and pastoral) on stream habitat, water chemistry and invertebrates, using propensity scores to control for potential confounding factors (e.g. climate, geology). Propensity scoring effectively reduced the collinearity between land cover and potential confounding variables, reducing the potential for covariate bias in estimated treatment–response relationships compared to conventional multiple regression. 3. Macroinvertebrate richness was significantly greater at sites with a higher proportion of improved pasture in their catchment or riparian zone, with these effects probably mediated by increased algal production from mild nutrient enrichment. In contrast, macroinvertebrate richness did not change with arable land cover, although sensitive species representation was lower under higher proportions of arable land cover, probably due to greatly elevated nutrient concentrations. 4. Synthesis and applications. Propensity modelling has great potential to address questions about pressures on ecosystems and organisms at the large spatial extents relevant to land‐use policy, where experimental approaches are not feasible and broad environmental changes often covary. Applied to the effects of agricultural land cover on stream systems, this approach identified reduced nutrient loading from arable farms as a priority for land management. On this specific issue, our data and analysis support the use of riparian or catchment‐scale measures to reduce nutrient delivery to sensitive water bodies

A World Wide View of Browsing the World Wide Web

In this paper, we perform the first large-scale study of how people spend time on the web. Our study is based on anonymous, aggregate telemetry data from several hundred million Google Chrome users who have explicitly enabled sharing URLs with Google and who have usage statistic reporting enabled. We analyze the distribution of web traffic, the types of websites that people visit and spend the most time on, the differences between desktop and mobile browsing behavior, the geographical differences in web usage, and the most popular websites in regions worldwide. Our study sheds light on online user behavior and how the research community can more accurately analyze the web in the future