1,297 research outputs found

    Estimation of sparse generalized linear models: the dglars package

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    dglars is a public available R package that implements the method proposed in Augugliaro, Mineo and Wit (2013) developed to study the sparse structure of a generalized linear model. This method, called dgLARS, is based on a differential geometrical extension of the least angle regression method (LARS). The core of the dglars package consists of two algorithms implemented in Fortran 90 to efficiently compute the solution curve; specifically a predictor-corrector algorithm and a cyclic coordinate descent algorithm

    The crustacean fauna of Bayan Onjuul area (Tôv Province, Mongolia) (Crustacea: Branchiopoda, Copepoda, Ostracoda)

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    Due to the wide extension of the country and to the shortness of the ice-free season, the inlandwater crustacean fauna of Mongolia is, to date, incompletely known. However, based on the available literature, Mongolian inland waters appear to be characterised by a high biodiversity, including some taxa still waiting to be described. Novel data on the branchiopod, copepod, and ostracod crustaceans from central Mongolian steppe, from the “Tuul” and “Umard goviin guveet-Khalhiin” hydrographical basins, are presented herein. While large branchiopods, some anomopod families, and copepods are well-represented in the collected samples, ostracods are rare, and the anomopod family Chydoridae is apparently absent in the sampled water bodies. The anomopod Macrothrix dadayi and the cyclopoid Microcyclops afghanicus are here reported for the first time for the Mongolian fauna. Furthermore, two branchiopods (i.e. Moina sp. and Artemia sp.), three copepods (i.e. Diacyclops sp., Arctodiaptomus cf. alpinus, and Arctodiaptomus cf. wierzejskii), and one ostracod taxon (i.e. Heterocypris sp.), were not identified to species level and therefore deserve further study. The main ecological determinants of species distribution in the study area were examined using canonical multivariate analysis, which explained around 40% of total variation of the species similarity matrix; the main environmental drivers of crustacean assemblages in the study area were elevation, water turbidity, water temperature and electrical conductivity. The ecological preferences of crustacean species in the area are briefly discussed

    DgCox: a differential geometric approach for high-dimensional Cox proportional hazard models

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    Many clinical and epidemiological studies rely on survival modelling to detect clinically relevant factors that affect various event histories. With the introduction of high-throughput technologies in the clinical and even large-scale epidemiological studies, the need for inference tools that are able to deal with fat data-structures, i.e., relatively small number of observations compared to the number of features, is becoming more prominent. This paper will introduce a principled sparse inference methodology for proportional hazards modelling, based on differential geometrical analyses of the high-dimensional likelihood surface

    Fast, Autonomous Flight in GPS-Denied and Cluttered Environments

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    One of the most challenging tasks for a flying robot is to autonomously navigate between target locations quickly and reliably while avoiding obstacles in its path, and with little to no a-priori knowledge of the operating environment. This challenge is addressed in the present paper. We describe the system design and software architecture of our proposed solution, and showcase how all the distinct components can be integrated to enable smooth robot operation. We provide critical insight on hardware and software component selection and development, and present results from extensive experimental testing in real-world warehouse environments. Experimental testing reveals that our proposed solution can deliver fast and robust aerial robot autonomous navigation in cluttered, GPS-denied environments.Comment: Pre-peer reviewed version of the article accepted in Journal of Field Robotic

    The combination of heterogeneous photocatalysis with chemical and physical operations: a tool for improving the photoprocess performance

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    Heterogeneous photocatalysis is a process of great potential for pollutant abatement and waste treatment. In order to improve the overall performance of the photoprocess, heterogeneous photocatalysis is being combined with physical or chemical operations, which affect the chemical kinetics and/or the overall ef\ufb01ciency. This review addresses the various possibilities to couple heterogeneous photocatalysis with other technologies to photodegrade organic and inorganic pollutants dissolved in actual or synthetic aqueous ef\ufb02uents. These combinations increase the photoprocess ef\ufb01ciency by decreasing the reaction time in respect to the separated operations or they decrease the cost in respect of heterogeneous photocatalysis alone, generally in terms of light energy. Depending on the operation coupled with heterogeneous photocatalysis, two categories of combinations exist. When the coupling is with ultrasonic irradiation, photo-Fenton reaction, ozonation, or electrochemical treatment, the combination affects the photocatalytic mechanisms thus improving the ef\ufb01ciency of the photocatalytic process. When the coupling is with biological treatment, membrane reactor, membrane photoreactor, or physical adsorption, the combination does not affect the photocatalytic mechanisms but it improves the ef\ufb01ciency of the overall process. The choice of the coupling is related to the type of wastewater to be treated. A synergistic effect, giving rise to an improvement of the ef\ufb01ciency of the photocatalytic process, has been reported in the literature for many cases

    Enhancing selectivity in photocatalytic formation of p-anisaldehyde in aqueous suspension under solar light irradiation via TiO2 N-doping

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    The photocatalytic partial oxidation of 4-methoxybenzyl alcohol to the corresponding aldehyde (p-anisaldehyde) was performed under simulated solar irradiation by using home prepared N-doped TiO2 catalysts. The photocatalysts were prepared by a sol–gel method, using TiCl4 as TiO2 precursor and NH4Cl, urea or NH4OH as N-doping sources. A commercial TiO2 (Degussa P25) was also used for comparison aims. The prepared catalysts were characterized by BET specific surface area, XRD, ESEM and UV-vis spectroscopy. The reactivity results show that (i) the doped catalysts are predominantly amorphous, and they show selectivity values far higher than those of the corresponding undoped ones and of well crystallized catalysts – even if the last ones show a higher activity – and (ii) exploitation of solar light significantly increases the reaction selectivity. In addition, different light sources were also used in order to investigate the effect of radiation wavelength ranges on the reactivity and selectivity to aldehyde

    Regulating Internet Trade in CITES Species

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    Wild collection of species that are or may be endangered by collection from the wild for international commerce is regulated under the The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) for 176 member States. Internet commerce is a relatively a new route for such trade and is rarely included in CITES statistics. By comparing information from an international on-line auction system with official CITES records on international trade, we discovered that only around 10% of the specimens of cacti listed on CITES Appendix I traded in 2010 were even potentially legal. Clearly, such trade over the Internet easily bypasses CITES trade regulations and should be monitored in future to ensure the effective protection of CITES listed species
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