The ultracool dwarf DENIS-P J104814.7-395606. Chromospheres and coronae at the low-mass end of the main-sequence

We have obtained an XMM-Newton observation and a broad-band spectrum from the ultraviolet to the near infrared with X-Shooter for one of the nearest M9 dwarfs, DENIS-P J1048-3956 (4pc). We integrate these data by a compilation of activity parameters for ultracool dwarfs from the literature with the aim to advance our understanding of these objects by comparing them to early-M type dwarf stars and the Sun. Our deep XMM-Newton observation has led to the first X-ray detection of DENIS-P J1048-3956 (log Lx = 25.1) as well as the first measurement of its V band brightness (V = 17.35mag). Flux-flux relations between X-ray and chromospheric activity indicators are here for the first time extended into the regime of the ultracool dwarfs. The approximate agreement of DENIS-P J1048-3956 and other ultracool dwarfs with flux-flux relations for early-M dwarfs suggests that the same heating mechanisms work in the atmospheres of ultracool dwarfs, albeit weaker as judged from their lower fluxes. The observed Balmer decrements of DENIS-P J1048-3956 are compatible with optically thick plasma in LTE at low, nearly photospheric temperature or optically thin LTE plasma at 20000K. Describing the decrements with CaseB recombination requires different emitting regions for Halpha and the higher Balmer lines. The high observed Halpha/Hbeta flux ratio is also poorly fitted by the optically thin models. We derive a similarly high value for the Halpha/Hbeta ratio of vB10 and LHS2065 and conclude that this may be a characteristic of ultracool dwarfs. We add DENIS-P J1048-3956 to the list of ultracool dwarfs detected in both the radio and the X-ray band. The Benz-Guedel relation between radio and X-ray luminosity of late-type stars is well-known to be violated by ultracool dwarfs. We speculate on the presence of two types of ultracool dwarfs with distinct radio and X-ray behavior.Comment: accepted for publication in Astronomy & Astrophysic

Classification of Leukocytes Using Meta-Learning and Color Constancy Methods

In the human healthcare area, leukocytes are very important blood cells for the diagnosis of different pathologies, like leukemia. Recent technology and image-processing methods have contributed to the image classification of leukocytes. Especially, machine learning paradigms have been used for the classification of leukocyte images. However, reported models do not leverage the knowledge produced by the classification of leukocytes to solve similar tasks. For example, the knowledge can be reused to classify images collected with different types of microscopes and image-processing techniques. Therefore, we propose a meta-learning methodology for the classification of leukocyte images using different color constancy methods involving previous knowledge. Our methodology is trained with a specific task at the meta-level, and the knowledge produced is used to solve a different task at the base-level. For the meta-level, we implemented meta-models based on Xception, and for the base-level, we used support vector machine classifiers. Besides, we analyzed the Shades of Gray color constancy method commonly used in skin lesion diagnosis and now implemented for leukocyte images. Our methodology, at the meta-level, achieved 89.28% for precision, 95.65% for sensitivity, 91.78% for F1-score, and 94.40% for accuracy. These scores are competitive regarding the reported state-of-the-art models, especially the sensitivity which is very important for imbalanced datasets, and our meta-model outperforms previous works by +2.25%. Additionally, for the basophil images that were acquired from a chronic myeloid leukemia-positive sample, our meta-model obtained 100% for sensitivity. Moreover, we present an algorithm that generates a new conditioned output at the base-level obtaining highly competitive scores of 91.56% for sensitivity and F1 scores, 95.61% for precision, and 96.47% for accuracy. The findings indicate that our proposed meta-learning methodology can be applied to other medical image classification tasks and achieve high performances by reusing knowledge and reducing the training time for new similar tasks

Assessing Code Authorship: The Case of the Linux Kernel

Code authorship is a key information in large-scale open source systems. Among others, it allows maintainers to assess division of work and identify key collaborators. Interestingly, open-source communities lack guidelines on how to manage authorship. This could be mitigated by setting to build an empirical body of knowledge on how authorship-related measures evolve in successful open-source communities. Towards that direction, we perform a case study on the Linux kernel. Our results show that: (a) only a small portion of developers (26 %) makes significant contributions to the code base; (b) the distribution of the number of files per author is highly skewed --- a small group of top authors (3 %) is responsible for hundreds of files, while most authors (75 %) are responsible for at most 11 files; (c) most authors (62 %) have a specialist profile; (d) authors with a high number of co-authorship connections tend to collaborate with others with less connections.Comment: Accepted at 13th International Conference on Open Source Systems (OSS). 12 page

Non-line-of-sight snapshots and background mapping with an active corner camera

The ability to form reconstructions beyond line-of-sight view could be transformative in a variety of fields, including search and rescue, autonomous vehicle navigation, and reconnaissance. Most existing active non-line-of-sight (NLOS) imaging methods use data collection steps in which a pulsed laser is directed at several points on a relay surface, one at a time. The prevailing approaches include raster scanning of a rectangular grid on a vertical wall opposite the volume of interest to generate a collection of confocal measurements. These and a recent method that uses a horizontal relay surface are inherently limited by the need for laser scanning. Methods that avoid laser scanning to operate in a snapshot mode are limited to treating the hidden scene of interest as one or two point targets. In this work, based on more complete optical response modeling yet still without multiple illumination positions, we demonstrate accurate reconstructions of foreground objects while also introducing the capability of mapping the stationary scenery behind moving objects. The ability to count, localize, and characterize the sizes of hidden objects, combined with mapping of the stationary hidden scene, could greatly improve indoor situational awareness in a variety of applications

Development and Characterization of Microsatellite Markers for the Cape Gooseberry Physalis peruviana

Physalis peruviana, commonly known as Cape gooseberry, is an Andean Solanaceae fruit with high nutritional value and interesting medicinal properties. In the present study we report the development and characterization of microsatellite loci from a P. peruviana commercial Colombian genotype. We identified 932 imperfect and 201 perfect Simple Sequence Repeats (SSR) loci in untranslated regions (UTRs) and 304 imperfect and 83 perfect SSR loci in coding regions from the assembled Physalis peruviana leaf transcriptome. The UTR SSR loci were used for the development of 162 primers for amplification. The efficiency of these primers was tested via PCR in a panel of seven P. peruviana accessions including Colombia, Kenya and Ecuador ecotypes and one closely related species Physalis floridana. We obtained an amplification rate of 83% and a polymorphic rate of 22%. Here we report the first P. peruviana specific microsatellite set, a valuable tool for a wide variety of applications, including functional diversity, conservation and improvement of the species

Convergence of the Magnus series

The Magnus series is an infinite series which arises in the study of linear ordinary differential equations. If the series converges, then the matrix exponential of the sum equals the fundamental solution of the differential equation. The question considered in this paper is: When does the series converge? The main result establishes a sufficient condition for convergence, which improves on several earlier results.Comment: 11 pages; v2: added justification for conjecture, minor clarifications and correction

Verkenning verwerkingsopties bedrijfsmatig gemengd kunststofverpakkingsafval

Within this project, an inventory has been made of the suitable processing options for processing plastic packaging waste of the Dutch state government. Hereby the technical feasibility of different options is analysed, but also readiness in the Netherlands (within the next 5 years), related cost and environmental impact. The separately collected plastic packaging waste of the Dutch state government has been studied during the last months of 2018. The composition was studied both with regard to the material composition and the types of packages and objects that are present. This material was sampled from five different locations in twofold. The separately collected material is composed of 60% plastics, small amounts of beverage cartons and metals (both 3%) and two non-targeted materials – paper & board and organic materials – in relatively large amounts (both approximately 17%). Currently, this material cannot be processed in conventional sorting facilities for post-consumer plastic packaging waste due to the relatively high concentrations of both contaminants. Ideally, the collection method is adapted in such a manner that the concentration of both contaminants is lowered below 15% or even better below 10%. This can potentially be achieved by information campaigns towards the users, a change in the waste collection system (the size of the opening of the waste collection bins, use of icons and the grouping of the waste bins for the various materials). Subsequently, the separately collected plastic waste can be treated at conventional sorting facilities for post-consumer lightweight packaging waste. An existing model for post-consumer plastic packaging waste was used to approximate the flows of the plastic packages through conventional sorting and recycling companies. The model predicts that roughly 58 tons of washed milled goods can be made from the separately collected plastic packaging waste. In case these recycled plastics are used in applications where virgin plastics are replaced then this will approximately result in a reduction of the greenhouse gases of 239 tons CO2 equivalents. The research of alternative methods shows that only the mechanical recovery of plastics from residual waste is ready in the Netherlands. This demands that the residual waste of the Dutch government will be processed in a central waste sorting facility and this is financially less attractive. Magnetic density separation is likely to develop within 5 years’ time to a robust alternative, but with currently unknown financial consequences. Other alternative processing options are not yet ready or are only a partial solution. Therefore the current system of separate collection, sorting and mechanical recycling is – based on our current knowledge – the most suitable processing option for the next 5 years