Effects of Vision on Dynamic Stability Against Backward Loss of Balance in Young and Elderly Subjects

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Simultaneous Den Use by Arctic Foxes and Wolves at a Den Site in Nunavut, Canada

Arctic foxes (Alopex lagopus) and wolves (Canis lupus) often use similar den sites. Interspecific interactions and competition for den sites are therefore possible among these species. At the Kangowan River in Nunavut, Canada, we observed arctic foxes and wolves simultaneously using a den site for pup-rearing during a two-day period in the summer of 2000. We also found evidence that both species had used the den site in May that year. Interspecific interactions in summer included avoidance, tolerance, and aggression. Foxes and wolves used separate entrances and did not appear to share a common space. Our observations of arctic foxes and wolves occupying a den site concurrently suggest that avoidance and interspecific tolerance may have facilitated coexistence at this den site.Les renards arctiques (Alopex lagopus) et les loups (Canis lupus) s’installent souvent dans des tanières du même genre. Par conséquent, il est possible que chez ces espèces, il y ait des interactions inter-espèces et une certaine concurrence pour l’obtention des tanières. À la rivière Kangowan, dans le Nunavut, au Canada, on a observé des renards arctiques et des loups qui se servaient simultanément d’une tanière pour élever leurs petits pendant une période de deux jours à l’été 2000. On a également trouvé des preuves que ces deux espèces s’étaient servies de la tanière au mois de mai de cette même année. L’été, les interactions inter-espèces prenaient la forme de l’évitement, de la tolérance et de l’agression. Les renards et les loups empruntaient des entrées différentes et ne donnaient pas l’impression de partager des lieux communs. Par ailleurs, nos observations des renards arctiques et des loups qui occupent une même tanière en même temps laissent croire que l’évitement et la tolérance inter-espèces pourraient avoir joué un rôle dans la coexistence à cette tanière

Foraging Behaviours of Wolverines at a Large Arctic Goose Colony

At the large Ross's goose and lesser snow goose colony at Karrak Lake, Nunavut, Canada, we saw wolverines kill two geese, take 13 eggs from 12 goose nests, and take three goose carcasses from two fox dens. Wolverines also made unsuccessful attempts to capture geese and frequently ignored eggs from nests where geese had fled the approaching wolverine. Most foods (all geese killed by wolverines and 80% of the eggs) were cached for later use, whereas few foods were eaten immediately (20% of the eggs and part of a goose taken from a fox den, which was later lost) or lost (all geese taken from fox dens). Wolverines spent little time caching foods (e.g., some foods were never covered), which suggests that recovery of these foods was not crucial to wolverines. When taking foods from fox dens, wolverines were mobbed by foxes; as a result, only one wolverine managed to consume part of a goose carcass taken from a fox den. These observations illustrate the opportunistic nature of wolverines and suggest that their scavenging success may be influenced by how well foods are defended.À l'importante colonie d'oies de Ross et de petites oies des neiges située à Karrak Lake au Nunavut (Canada), on a vu des carcajous tuer deux oies, prendre 13 oeufs dans 12 nids d'oies, et prendre trois carcasses d'oies dans deux terriers de renards. Les carcajous ont aussi essayé, sans succès, de capturer des oies et ils ignoraient souvent les oeufs des nids que les oies avaient fuis à leur approche. La plupart des aliments (toutes les oies tuées par les carcajous et 80 p. cent des oeufs) étaient dissimulés pour utilisation ultérieure, tandis que peu d'aliments étaient consommés tout de suite (20 p. cent des oeufs et une partie d'une oie prélevée dans un terrier de renard, qui a été perdue par la suite) ou perdus (toutes les oies prises dans les terriers de renards). Les carcajous passaient peu de temps à dissimuler les aliments (p. ex., certains n'étaient jamais recouverts), ce qui suggère qu'il n'est pas crucial pour eux de les retrouver. Quand les carcajous prenaient des aliments dans les terriers de renards, ils étaient assaillis par les occupants; en conséquence, un seul carcajou est parvenu à consommer une partie d'une carcasse d'oie prise dans un terrier de renard. Ces observations illustrent la nature opportuniste des carcajous et suggèrent que leur succès de récupération pourrait être influencé par la façon dont les aliments sont défendus

Eleven years of radio monitoring of the Type IIn supernova SN 1995N

We present radio observations of the optically bright Type IIn supernova SN 1995N. We observed the SN at radio wavelengths with the Very Large Array (VLA) for 11 years. We also observed it at low radio frequencies with the Giant Metrewave Radio Telescope (GMRT) at various epochs within $6.5-10$ years since explosion. Although there are indications of an early optically thick phase, most of the data are in the optically thin regime so it is difficult to distinguish between synchrotron self absorption (SSA) and free-free absorption (FFA) mechanisms. However, the information from other wavelengths indicates that the FFA is the dominant absorption process. Model fits of radio emission with the FFA give reasonable physical parameters. Making use of X-ray and optical observations, we derive the physical conditions of the shocked ejecta and the shocked CSM.Comment: 22 pages, 2 tables, 13 figures, Accepted for publication in Astrophysical Journa

A computational framework to emulate the human perspective in flow cytometric data analysis

Background: In recent years, intense research efforts have focused on developing methods for automated flow cytometric data analysis. However, while designing such applications, little or no attention has been paid to the human perspective that is absolutely central to the manual gating process of identifying and characterizing cell populations. In particular, the assumption of many common techniques that cell populations could be modeled reliably with pre-specified distributions may not hold true in real-life samples, which can have populations of arbitrary shapes and considerable inter-sample variation. <p/>Results: To address this, we developed a new framework flowScape for emulating certain key aspects of the human perspective in analyzing flow data, which we implemented in multiple steps. First, flowScape begins with creating a mathematically rigorous map of the high-dimensional flow data landscape based on dense and sparse regions defined by relative concentrations of events around modes. In the second step, these modal clusters are connected with a global hierarchical structure. This representation allows flowScape to perform ridgeline analysis for both traversing the landscape and isolating cell populations at different levels of resolution. Finally, we extended manual gating with a new capacity for constructing templates that can identify target populations in terms of their relative parameters, as opposed to the more commonly used absolute or physical parameters. This allows flowScape to apply such templates in batch mode for detecting the corresponding populations in a flexible, sample-specific manner. We also demonstrated different applications of our framework to flow data analysis and show its superiority over other analytical methods. <p/>Conclusions: The human perspective, built on top of intuition and experience, is a very important component of flow cytometric data analysis. By emulating some of its approaches and extending these with automation and rigor, flowScape provides a flexible and robust framework for computational cytomics

Towards Molecular Simulations that are Transparent, Reproducible, Usable By Others, and Extensible (TRUE)

Systems composed of soft matter (e.g., liquids, polymers, foams, gels, colloids, and most biological materials) are ubiquitous in science and engineering, but molecular simulations of such systems pose particular computational challenges, requiring time and/or ensemble-averaged data to be collected over long simulation trajectories for property evaluation. Performing a molecular simulation of a soft matter system involves multiple steps, which have traditionally been performed by researchers in a "bespoke" fashion, resulting in many published soft matter simulations not being reproducible based on the information provided in the publications. To address the issue of reproducibility and to provide tools for computational screening, we have been developing the open-source Molecular Simulation and Design Framework (MoSDeF) software suite. In this paper, we propose a set of principles to create Transparent, Reproducible, Usable by others, and Extensible (TRUE) molecular simulations. MoSDeF facilitates the publication and dissemination of TRUE simulations by automating many of the critical steps in molecular simulation, thus enhancing their reproducibility. We provide several examples of TRUE molecular simulations: All of the steps involved in creating, running and extracting properties from the simulations are distributed on open-source platforms (within MoSDeF and on GitHub), thus meeting the definition of TRUE simulations

Pion-nucleus elastic scattering on 12C, 40Ca, 90Zr, and 208Pb at 400 and 500 MeV

Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at energies where second-order corrections to impulse approximation calculations should be small. The results are compared with other data sets at similar energies, and with four different first-order impulse approximation calculations. Significant disagreement exists between the calculations and the data from this experiment