Statistics, distillation, and ordering emergence in a two-dimensional stochastic model of particles in counterflowing streams

In this paper, we proposed a stochastic model which describes two species of particles moving in counterflow. The model generalizes the theoretical framework describing the transport in random systems since particles can work as mobile obstacles, whereas particles of one species move in opposite direction to the particles of the other species, or they can work as fixed obstacles remaining in their places during the time evolution. We conducted a detailed study about the statistics concerning the crossing time of particles, as well as the effects of the lateral transitions on the time required to the system reaches a state of complete geographic separation of species. The spatial effects of jamming were also studied by looking into the deformation of the concentration of particles in the two-dimensional corridor. Finally, we observed in our study the formation of patterns of lanes which reach the steady state regardless the initial conditions used for the evolution. A similar result is also observed in real experiments involving charged colloids motion and simulations of pedestrian dynamics based on Langevin equations, when periodic boundary conditions are considered (particles counterflow in a ring symmetry). The results obtained through Monte Carlo numerical simulations and numerical integrations are in good agreement with each other. However, differently from previous studies, the dynamics considered in this work is not Newton-based, and therefore, even artificial situations of self-propelled objects should be studied in this first-principle modeling.Comment: 27 pages, 13 figure

Towards an Achievable Performance for the Loop Nests

Numerous code optimization techniques, including loop nest optimizations, have been developed over the last four decades. Loop optimization techniques transform loop nests to improve the performance of the code on a target architecture, including exposing parallelism. Finding and evaluating an optimal, semantic-preserving sequence of transformations is a complex problem. The sequence is guided using heuristics and/or analytical models and there is no way of knowing how close it gets to optimal performance or if there is any headroom for improvement. This paper makes two contributions. First, it uses a comparative analysis of loop optimizations/transformations across multiple compilers to determine how much headroom may exist for each compiler. And second, it presents an approach to characterize the loop nests based on their hardware performance counter values and a Machine Learning approach that predicts which compiler will generate the fastest code for a loop nest. The prediction is made for both auto-vectorized, serial compilation and for auto-parallelization. The results show that the headroom for state-of-the-art compilers ranges from 1.10x to 1.42x for the serial code and from 1.30x to 1.71x for the auto-parallelized code. These results are based on the Machine Learning predictions.Comment: Accepted at the 31st International Workshop on Languages and Compilers for Parallel Computing (LCPC 2018

Indigenous demosponge spicules in a Late Devonian stromatoporoid basal skeleton from the Frasnian of Belgium

This paper records the first example of a demosponge spicule framework in a single specimen of a Devonian stromatoporoid from the Frasnian of southern Belgium. The small sample (2.5 × 2 cm) is a component in a brecciated carbonate from a carbonate mound in La Boverie Quarry 30 km east of Dinant. Because of the small size of the sample, generic identification is not confirmed, but the stromatoporoid basal skeleton is similar to the genus Stromatopora. The spicules are arranged in the calcified skeleton, but not in the gallery space, and are recrystallized as multi-crystalline calcite. The spicules fall into two size ranges: 10-20 μm diameter and 500-2000 μm long for the large ones and between 5-15 μm diameter and 50-100 μm length for the small ones. In tangential section, the spicules are circular, they have a simple structure, and no axial canal has been preserved. The large spicules are always monaxons, straight or slightly curved styles or strongyles. The spicules most closely resemble halichondrid/axinellid demosponge spicules and are important rare evidence of the existence of spicules in Palaeozoic stromatoporoids, reinforcing the interpretation that stromatoporoids were sponges. The basal skeleton may have had an aragonitic spherulitic mineralogy. Furthermore, the spicules indicate that this stromatoporoid sample is a demosponge. © 2014 Lethaia Foundation. Published by John Wiley & Sons Ltd

Enhanced Synthesis of Metal-Organic Frameworks on the Surface of Electrospun Cellulose Nanofibers

This study reports the in situ crystal growth of HKUST-1 on electrospun cellulose nanofibers. Two different methods for introducing carboxyl groups on the nanofiber surface were used; HKUST-1 was then synthesized on the cellulose nanofiber surface using a layer-by-layer approach. The distribution of HKUST-1 on the nanofiber surface was highly dependent on the type of anionic pretreatment. The loading of HKUST-1 on the nanofiber surface could be controlled by the layer-by-layer synthesis and the BET surface area could be increased by a factor of 44 to 440 m2 g-1

Expression of Distal-less, dachshund, and optomotor blind in Neanthes arenaceodentata (Annelida, Nereididae) does not support homology of appendage-forming mechanisms across the Bilateria

The similarity in the genetic regulation of arthropod and vertebrate appendage formation has been interpreted as the product of a plesiomorphic gene network that was primitively involved in bilaterian appendage development and co-opted to build appendages (in modern phyla) that are not historically related as structures. Data from lophotrochozoans are needed to clarify the pervasiveness of plesiomorphic appendage forming mechanisms. We assayed the expression of three arthropod and vertebrate limb gene orthologs, Distal-less (Dll), dachshund (dac), and optomotor blind (omb), in direct-developing juveniles of the polychaete Neanthes arenaceodentata. Parapodial Dll expression marks premorphogenetic notopodia and neuropodia, becoming restricted to the bases of notopodial cirri and to ventral portions of neuropodia. In outgrowing cephalic appendages, Dll activity is primarily restricted to proximal domains. Dll expression is also prominent in the brain. dac expression occurs in the brain, nerve cord ganglia, a pair of pharyngeal ganglia, presumed interneurons linking a pair of segmental nerves, and in newly differentiating mesoderm. Domains of omb expression include the brain, nerve cord ganglia, one pair of anterior cirri, presumed precursors of dorsal musculature, and the same pharyngeal ganglia and presumed interneurons that express dac. Contrary to their roles in outgrowing arthropod and vertebrate appendages, Dll, dac, and omb lack comparable expression in Neanthes appendages, implying independent evolution of annelid appendage development. We infer that parapodia and arthropodia are not structurally or mechanistically homologous (but their primordia might be), that Dll’s ancestral bilaterian function was in sensory and central nervous system differentiation, and that locomotory appendages possibly evolved from sensory outgrowths

Lattice Gas model to describe a nightclub dynamics

In this work, we propose a simple stochastic agent-based model to describe the revenue dynamics of a nightclub venue based on the relationship between profit and spatial occupation. The system consists of an underlying square lattice (nightclub's dance floor) where every attendee (agent) is allowed to move to its first neighboring cells. Each guess has a characteristic delayed time between drinks, denoted as $\tau$, after which it will show an urge to drink. At this moment, the attendee will tend to move towards the bar where a drink will be bought. After it has left the bar zone, $\tau$ time steps should pass so it shows once again the need to drink. Our model among other points show that it is no use filling the bar to obtain profit, and optimization should be analyzed. This can be done in a more secure way taking into consideration the ratio between income and ticket cost.Comment: 13 pages, 6 figure

Mobile-to-clogging transition in a Fermi-like model of counterflowing particles

In this paper we propose a generalized model for the motion of a two-species self-driven objects ranging from a scenario of a completely random environment of particles of negligible excluded volume to a more deterministic regime of rigid objects in an environment. Each cell of the system has a maximum occupation level called σ max . Both species move in opposite directions. The probability of any given particle to move to a neighboring cell depends on the occupation of this cell according to a Fermi-Dirac-like distribution, considering a parameter α that controls the system randomness. We show that for a certain α = α c the system abruptly transits from a mobile scenario to a clogged state, which is characterized by condensates. We numerically describe the details of this transition by coupled partial differential equations (PDE) and Monte Carlo (MC) simulations that are in good agreement

User emotional interaction processor: a tool to support the development of GUIs through physiological user monitoring

Ever since computers have entered humans' daily lives, the activity between the human and the digital ecosystems has increased. This increase encourages the development of smarter and more user-friendly human-computer interfaces. However, to test these interfaces, the means of interaction have been limited, for the most part restricted to the conventional interface, the "manual" interface, where physical input is required, where participants who test these interfaces use a keyboard, mouse, or a touch screen, and where communication between participants and designers is required. There is another method, which will be applied in this dissertation, which does not require physical input from the participants, which is called Affective Computing. This dissertation presents the development of a tool to support the development of graphical interfaces, based on the monitoring of psychological and physiological aspects of the user (emotions and attention), aiming to improve the experience of the end user, with the ultimate goal of improving the interface design. The development of this tool will be described. The results, provided by designers from an IT company, suggest that the tool is useful but that the optimized interface generated by it still has some flaws. These flaws are mainly related to the lack of consideration of a general context in the interface generation process.Desde que os computadores entraram na vida diária dos humanos, a atividade entre o ecossistema humano e o digital tem aumentado. Este aumento estimula o desenvolvimento de interfaces humano-computador mais inteligentes e apelativas ao utilizador. No entanto, para testar estas interfaces, os meios de interação têm sido limitados, em grande parte restritos à interface convencional, a interface "manual", onde é preciso "input" físico, onde os participantes que testam estas interface, usam um teclado, um rato ou um "touch screen", e onde a comunicação dos participantes com os designers é necessária. Existe outro método, que será aplicado nesta dissertação, que não necessita de "input" físico dos participantes, que se denomina de "Affective Computing". Esta dissertação apresenta o desenvolvimento de uma ferramenta de suporte ao desenvolvimento de interfaces gráficas, baseada na monitorização de aspetos psicológicos e fisiológicos do utilizador (emoções e atenção), visando melhorar a experiência do utilizador final, com o objetivo último de melhorar o design da interface. O desenvolvimento desta ferramenta será descrito. Os resultados, dados por designers de uma empresa de IT, sugerem que esta é útil, mas que a interface otimizada gerada pela mesma tem ainda algumas falhas. Estas falhas estão, principalmente, relacionadas com a ausência de consideração de um contexto geral no processo de geração da interface