813 research outputs found

    Counterterms vs. Dualities

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    We investigate and clarify the mutual compatibility of the higher order corrections arising in supergravity and string theory effective actions and the non-linear duality symmetries of these theories. Starting from a conventional tree level action leading to duality invariant equations of motion, we show how to accommodate duality invariant counterterms given as functionals of both electric and magnetic fields in a perturbative expansion, and to deduce from them a non-polynomial bona fide action satisfying the Gaillard-Zumino constraint. There exists a corresponding consistency constraint in the non-covariant Henneaux-Teitelboim formalism which ensures that one can always restore diffeomorphism invariance by perturbatively solving this functional identity. We illustrate how this procedure works for the R^2 \nabla F \nabla F and F^4 counterterms in Maxwell theory.Comment: 15 page

    Food Recognition using Fusion of Classifiers based on CNNs

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    With the arrival of convolutional neural networks, the complex problem of food recognition has experienced an important improvement in recent years. The best results have been obtained using methods based on very deep convolutional neural networks, which show that the deeper the model,the better the classification accuracy will be obtain. However, very deep neural networks may suffer from the overfitting problem. In this paper, we propose a combination of multiple classifiers based on different convolutional models that complement each other and thus, achieve an improvement in performance. The evaluation of our approach is done on two public datasets: Food-101 as a dataset with a wide variety of fine-grained dishes, and Food-11 as a dataset of high-level food categories, where our approach outperforms the independent CNN models

    AN INITIAL ASSESSMENT OF EXOTIC AND INVASIVE PLANT SPECIES IN SRI LANKA's FLORA AND THEIR IMPACTS

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    Globally, exotic naturalized plants that behave invasively and occupy wildlands areresponsible for greater losses of biodiversity than any other factor except habitat loss anddirect exploitation of plant species by people. About I - 2% of naturalized exotic speciesbecome invasive in behavior, infesting and sometimes destroying parks, preserves andrefuges. This occurs because the invasive plant species: have no natural enemies ordiseases present; spread rapidly due to high reproductive and dispersal capabilities; and outcompete native species.Publications relating to the Sri Lankan flora, and Master's theses available in the library ofDept. of Forestry and Enviromental Science at the University of Sri Jayewardenepuraregarding various Sri Lankan biological communities, provide the opportunity for anexamination of Sri Lanka's exotic flora and an initial attempt to assess their impact on SriLanka's plant communities. Tallying herbs and woody species by life form, habitatpreference and origin (indigenous, endemic or exotic) revealed the following. Twenty-fivepercent of Sri Lanka's flora is exotic species (15.6% herbacious and 9.4% woody species)not including cultivated species not known to escape. Herbacious (34.6%) and liana's Ivines (19.5%) are the life forms with the highest percentage exotics. The largestproportion of the total number of exotic species is found in disturbed (22.6%) and wetforest (18.4%) habitats. Amongst herbacious species the proportion of exotics is also highin aquatic habitats (44.2%). Certain plant taxa contain species which readily naturalize inSri Lanka. Four plant families, Fabaceae, Verbeneaceae, Myrtaceae, and Rutaceae contain>55% of all woody exotics. The Poaceae, alone account for 28.6% of all exotic herbs.Species lists from Masters theses done on two wet zone forest reserves indicate seed bankscontain about 30% exotic species, while mature wet zone forests contain only 5 - 11%exotic species. If seed banks contain the seeds of exotic species underwhich the native ormature forest species can not germinate or survive, this would be cause for much concern.I! is certainly something that merits further research.Initial observations in the field were made of % cover by indigenous + endemic and exoticspecies along 7 randomly located transects in several different habitat types. Fieldmeasurements indicate Sri Lankan wetzone forests are highly resistant to exotics andinhibit potential invasive behavior. Except in young forest gaps (where up to 20% of covercan be exotic species) almost all cover is indigenous+endemic species. In disturbed lands,wet and low zone grasslands and aquatic habitat (fresh water pond) in Sri Lanka the casewas quite different. Greater than 80% of the cover was exotic species in random transectssampled in these three habitat typesThe total impact of the diverse assemblage of exotic species in Sri Lankan's should be ofsome concern. The exotics are competing with each other in some habitats which preventsanyone of them from taking over and forming a monospecific stand, but the indigenousspecies are forced out regardless. How widespread this is in other habitats in Sri Lankamerits further research so management recommendations can made.

    Geology of Smoke Hollow Area 8 Miles Southeast of Deerlodge, Powell County, Montana

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    This investigation was undertaken primarily as a problem in geologic mapping. The stratigraphy was studied as to the character, age, and sequence of the geologic formations that are exposed. The conclusions were based principally on the field relationships and lithology because no fossils were found

    Deep sea spy: a collaborative annotation tool

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    Since 2010, remote hydrothermal ecosystems are continuously being monitored using video cameras deployed on instrumented platforms. The acquisition of high-frequency video data from deep-sea observatories like EMSOAzores or Ocean Networks Canada provide information on species behaviour, feeding habits, growth, reproduction and organisms’ response to changes in environmental conditions. Video cameras acquire hourly data representing thousands of hours and Tera Bytes of footage but their manual processing is time-consuming and highly labour-intensive, and cannot be comprehensively undertaken by individual researchers. In order to help preliminary manual assessment of this huge imagery archive, a free online annotation tool was developed to gather contributions from a wider community. The Deep Sea Spy system offers a fun and engaging web interface to members of the public to help perform initial footage annotations. The platform now hosts 623 active annotators who contributed 179,663 annotations to 19,541 images. Preliminary analyses highlight a high variability among participants but show promising results to detect trends in species abundance variation over time. Ultimately, the information gathered via this approach can help improving the algorithms necessary to produce accurate automated detection in imagery using a machine learning approach

    Exploring Food Detection using CNNs

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    One of the most common critical factors directly related to the cause of a chronic disease is unhealthy diet consumption. In this sense, building an automatic system for food analysis could allow a better understanding of the nutritional information with respect to the food eaten and thus it could help in taking corrective actions in order to consume a better diet. The Computer Vision community has focused its efforts on several areas involved in the visual food analysis such as: food detection, food recognition, food localization, portion estimation, among others. For food detection, the best results evidenced in the state of the art were obtained using Convolutional Neural Network. However, the results of all these different approaches were gotten on different datasets and therefore are not directly comparable. This article proposes an overview of the last advances on food detection and an optimal model based on GoogLeNet Convolutional Neural Network method, principal component analysis, and a support vector machine that outperforms the state of the art on two public food/non-food datasets

    E{7(7)} Symmetry and Finiteness of N=8 Supergravity

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    We study N=8 supergravity deformed by the presence of the candidate counterterms. We show that even though they are invariant under undeformed E{7(7)}, all of the candidate counterterms violate the deformed E{7(7)} current conservation. The same conclusion follows from the uniqueness of the Lorentz and SU(8) covariant, E{7(7)} invariant unitarity constraint expressing the 56-dimensional E{7(7)} doublet via 28 independent vectors. Therefore E{7(7)} duality predicts the all-loop UV finiteness of perturbative N=8 supergravity.Comment: 18 page

    Performance of two formal tests based on martingales residuals to check the proportional hazard assumption and the functional form of the prognostic factors in flexible parametric excess hazard models.

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    : Net survival, the one that would be observed if the disease under study was the only cause of death, is an important, useful, and increasingly used indicator in public health, especially in population-based studies. Estimates of net survival and effects of prognostic factor can be obtained by excess hazard regression modeling. Whereas various diagnostic tools were developed for overall survival analysis, few methods are available to check the assumptions of excess hazard models. We propose here two formal tests to check the proportional hazard assumption and the validity of the functional form of the covariate effects in the context of flexible parametric excess hazard modeling. These tests were adapted from martingale residual-based tests for parametric modeling of overall survival to allow adding to the model a necessary element for net survival analysis: the population mortality hazard. We studied the size and the power of these tests through an extensive simulation study based on complex but realistic data. The new tests showed sizes close to the nominal values and satisfactory powers. The power of the proportionality test was similar or greater than that of other tests already available in the field of net survival. We illustrate the use of these tests with real data from French cancer registries.<br/

    String cosmology from Poisson-Lie T-dual sigma models on supermanifolds

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    We generalize the formulation of Poisson-Lie T-dual sigma models on manifolds to supermanifolds. In this respect, we formulate 1+1 dimensional string cosmological models on the Lie supergroup C^3 and its dual (A_1,1 + 2A)^0_(1,0,0), which are coupled to two fermionic fields. Then, we solve the equations of motion of the models and show that there is a essential singularity for the metric of the original model and its dual.Comment: 17 pages, Appendix and three references have adde

    Ectoplasm with an Edge

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    The construction of supersymmetric invariant actions on a spacetime manifold with a boundary is carried out using the "ectoplasm" formalism for the construction of closed forms in superspace. Non-trivial actions are obtained from the pull-backs to the bosonic bodies of closed but non-exact forms in superspace; finding supersymmetric invariants thus becomes a cohomology problem. For a spacetime with a boundary, the appropriate mathematical language changes to relative cohomology, which we use to give a general formulation of off-shell supersymmetric invariants in the presence of boundaries. We also relate this construction to the superembedding formalism for the construction of brane actions, and we give examples with bulk spacetimes of dimension 3, 4 and 5. The closed superform in the 5D example needs to be constructed as a Chern-Simons type of invariant, obtained from a closed 6-form displaying Weil triviality.Comment: 25 page
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