ABSTRACT In the first three years of operation, the Kepler mission found 3697 planet candidates (PCs) from a set of 18,406 transit-like features detected on more than 200,000 distinct stars. Vetting ...candidate signals manually by inspecting light curves and other diagnostic information is a labor intensive effort. Additionally, this classification methodology does not yield any information about the quality of PCs; all candidates are as credible as any other. The torrent of exoplanet discoveries will continue after Kepler, because a number of exoplanet surveys will have an even broader search area. This paper presents the application of machine-learning techniques to the classification of the exoplanet transit-like signals present in the Kepler light curve data. Transit-like detections are transformed into a uniform set of real-numbered attributes, the most important of which are described in this paper. Each of the known transit-like detections is assigned a class of PC; astrophysical false positive; or systematic, instrumental noise. We use a random forest algorithm to learn the mapping from attributes to classes on this training set. The random forest algorithm has been used previously to classify variable stars; this is the first time it has been used for exoplanet classification. We are able to achieve an overall error rate of 5.85% and an error rate for classifying exoplanets candidates of 2.81%.
Researchers need to focus on data collection, early-warning systems, flood protection and more. Deluges can trigger sudden and rapid torrents of run-off that flow down dry river beds and rocky ...channels. Because parched soils repel water rather than allowing it to soak in, flash floods can be more devastating in drylands than in wetter areas. To rectify this, the World Meteorological Organization is running a programme to provide weather forecasters and disaster-management agencies with real-time information around flash-flood threats (see go.nature.com/3xsw4fg). Promising projects include the World Bank's Global Program on NatureBased Solutions for Climate Resilience and the Sindh Resilience Project in Pakistan, as well as government-led water and soil conservation initiatives in the Loess Plateau in north-central China.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
Anatomic differences on the toe pad epithelial cells of torrent and tree frogs (elongated versus regular geometry) are believed to account for superior ability of torrent frogs to attach to surfaces ...in the presence of running water. Here, the friction properties of artificial hexagonal arrays of polydimethylsiloxane (PDMS) pillars (elongated and regular) in the presence of water are compared. Elongated pillar patterns show significantly higher friction in a direction perpendicular to the long axis. A low bending stiffness of the pillars and a high edge density of the pattern in the sliding direction are the key design criteria for the enhanced friction. The elongated patterns also favor orientation‐dependent friction. These findings have important implications for the development of new reversible adhesives for wet conditions.
The friction of artificial hexagonal arrays of polydimethylsiloxane pillars in the presence of water is studied. Arrays consisting of elongated pillars, resembling the structure of the toe pads of torrent frogs, are compared with arrays of hexagonal pillars as found in the toe pads of tree frogs. Elongated pillar patterns show significantly higher friction in a direction perpendicular to the long axis and favor orientation‐dependent friction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hepatitis C virus (HCV) infection is a leading cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma in humans and afflicts more than 58 million people worldwide. The HCV envelope ...E1 and E2 glycoproteins are essential for viral entry and comprise the primary antigenic target for neutralizing antibody responses. The molecular mechanisms of E1E2 assembly, as well as how the E1E2 heterodimer binds broadly neutralizing antibodies, remain elusive. Here, we present the cryo-electron microscopy structure of the membrane-extracted full-length E1E2 heterodimer in complex with three broadly neutralizing antibodies-AR4A, AT1209, and IGH505-at ~3.5-angstrom resolution. We resolve the interface between the E1 and E2 ectodomains and deliver a blueprint for the rational design of vaccine immunogens and antiviral drugs.
Abstract
The division and prediction of river basins provide important theoretical support for mountain torrents, flow direction control and governance. This paper takes Shuangliu District of Chengdu ...as the main research area. The experiment is supported by the elevation data of Fuhe River in Huanglongxi Town, Yong’an Town, Shuangliu District of Chengdu from 2020 to 2021. By constructing the model database, dividing the spatial unit of the basin and predicting the river trend, the arcswat model for the River Basin of Shuangliu District of Chengdu is established. The results show that the preliminary watershed area obtained by introducing elevation image analysis is the best. In the follow-up test, by combining the calculated results of hydrological system characteristics in the database with the weather data obtained from the world weather database, it better fitted the water conditions of Shuangliu area and showed excellent performance.
In the past decade, more than 300 people have died per year on average due to mountain torrents in China. Mountain torrents mostly occur in ungauged small and medium-sized catchments, so it is ...difficult to maintain high accuracy of flood prediction. In order to solve the problem of the low accuracy of flood simulation in the ungauged areas, this paper studies the influence of different methods on the parameter regionalization of distributed hydrological model parameters in hilly areas of Hunan Province. According to the terrain, landform, soil and land use characteristics of each catchment, we use Shortest Distance, Attribute Similarity, Support Vector Regression, Generative Adversarial Networks, Classification and Regression Tree and Random Forest methods to create parameter regionalization schemes. In total, 426 floods of 25 catchments are selected to calibrate the model parameters, and 136 floods of 8 catchments are used for verification. The results showed that the average values of the Nash–Sutcliffe coefficients of each scheme were 0.58, 0.64, 0.60, 0.66, 0.61 and 0.68, and the worst values were 0.27, 0.31, 0.25, 0.43, 0.35 and 0.59. The random forest model is the most stable solution and significantly outperforms other methods. Using the random forest model to regionalize parameters can improve the accuracy of flood simulation in ungauged areas, which is of great significance for flash flood forecasting and early warning.
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