Robustness: a New Form of Heredity Motivated by Dynamic Networks

We investigate a special case of hereditary property in graphs, referred to as {\em robustness}. A property (or structure) is called robust in a graph $G$ if it is inherited by all the connected spanning subgraphs of $G$. We motivate this definition using two different settings of dynamic networks. The first corresponds to networks of low dynamicity, where some links may be permanently removed so long as the network remains connected. The second corresponds to highly-dynamic networks, where communication links appear and disappear arbitrarily often, subject only to the requirement that the entities are temporally connected in a recurrent fashion ({\it i.e.} they can always reach each other through temporal paths). Each context induces a different interpretation of the notion of robustness. We start by motivating the definition and discussing the two interpretations, after what we consider the notion independently from its interpretation, taking as our focus the robustness of {\em maximal independent sets} (MIS). A graph may or may not admit a robust MIS. We characterize the set of graphs \forallMIS in which {\em all} MISs are robust. Then, we turn our attention to the graphs that {\em admit} a robust MIS (\existsMIS). This class has a more complex structure; we give a partial characterization in terms of elementary graph properties, then a complete characterization by means of a (polynomial time) decision algorithm that accepts if and only if a robust MIS exists. This algorithm can be adapted to construct such a solution if one exists

A new methodology for learning design

This paper describes the development of a new methodology for learning design. Our approach is predicated on the view that no one, simple, view of design is appropriate, because of the inherently messy and creative nature of design. Instead we are adopting an interactive and multi-faceted approach which consists of a series of cycles of user consultation, focus groups and workshops alongside the development of learning design tools and resources. In particular we will describe how we have adapted an existing mind mapping and argumentation tool, Compendium, so that it can be used as a means of guiding designers through the learning design decision making process in the creation of learning activities. We will describe the initial evaluations of the use of this tool, along with our findings to date on a series of fact finding exercises to better understand individual and team approaches to design

Quantifying the Evidential Value of Celebrity Endorsement: A p-Curve Analysis

Celebrity endorsements have long been used as a promotional tool in marketing communication. However, literature has documented inconsistent findings on the effects of celebrity endorsements compared to no endorsement or noncelebrity endorsements, suggesting a close examination about the reliability and robustness of celebrity endorsements is needed. This study conducted a p-curve analysis among two sets of published studies based on different comparison groups (celebrity endorsements vs. no celebrity endorsement; celebrity endorsements vs. noncelebrity endorsements) to investigate if both sets of studies contain an evidential value. The significantly right-skewed p curve suggests that both sets of published studies have some integrity. However, the studies that compared celebrity endorsements with no celebrity endorsements showed low statistical power. Theoretical and methodological implications for celebrity endorsement research were discussed

Genetic isolation by distance and landscape connectivity in the American marten ( Martes americana )

Empirical studies of landscape connectivity are limited by the difficulty of directly measuring animal movement. ‘Indirect' approaches involving genetic analyses provide a complementary tool to ‘direct' methods such as capture-recapture or radio-tracking. Here the effect of landscape on dispersal was investigated in a forest-dwelling species, the American marten (Martes americana) using the genetic model of isolation by distance (IBD). This model assumes isotropic dispersal in a homogeneous environment and is characterized by increasing genetic differentiation among individuals separated by increasing geographic distances. The effect of landscape features on this genetic pattern was used to test for a departure from spatially homogeneous dispersal. This study was conducted on two populations in homogeneous vs. heterogeneous habitat in a harvested boreal forest in Ontario (Canada). A pattern of IBD was evidenced in the homogeneous landscape whereas no such pattern was found in the near-by harvested forest. To test whether landscape structure may be accountable for this difference, we used effective distances that take into account the effect of landscape features on marten movement instead of Euclidean distances in the model of isolation by distance. Effective distances computed using least-cost modeling were better correlated to genetic distances in both landscapes, thereby showing that the interaction between landscape features and dispersal in Martes americana may be detected through individual-based analyses of spatial genetic structure. However, the simplifying assumptions of genetic models and the low proportions in genetic differentiation explained by these models may limit their utility in quantifying the effect of landscape structur

Mixing and transport of metals by gravitational instability-driven turbulence in galactic discs

Metal production in galaxies traces star formation, and is highly concentrated towards the centres of galactic discs. This suggests that galaxies should have inhomogeneous metal distributions with strong radial gradients, but observations of present-day galaxies show only shallow gradients with little azimuthal variation, implying the existence of a redistribution mechanism. We study the role of gravitational instability-driven turbulence as a mixing mechanism by simulating an isolated galactic disc at high resolution, including metal fields treated as passive scalars. Since any cylindrical field can be decomposed into a sum of Fourier–Bessel basis functions, we set up initial metal fields characterized by these functions and study how different modes mix. We find both shear and turbulence contribute to mixing, but the mixing strongly depends on the symmetries of the mode. Non-axisymmetric modes have decay times smaller than the galactic orbital period because shear winds them up to small spatial scales, where they are erased by turbulence. The decay time-scales for axisymmetric modes are much greater, though for all but the largest scale inhomogeneities the mixing time-scale is still short enough to erase chemical inhomogeneities over cosmological times. These different time-scales provide an explanation for why galaxies retain metallicity gradients while there is almost no variation at a fixed radius. Moreover, the comparatively long time-scales required for mixing axisymmetric modes may explain the greater diversity of metallicity gradients observed in high redshift galaxies as compared to local ones: these systems have not yet reached equilibrium between metal production and diffusion

Navigation in Curved Space-Time

A covariant and invariant theory of navigation in curved space-time with respect to electromagnetic beacons is written in terms of J. L. Synge's two-point invariant world function. Explicit equations are given for navigation in space-time in the vicinity of the Earth in Schwarzschild coordinates and in rotating coordinates. The restricted problem of determining an observer's coordinate time when their spatial position is known is also considered

No sólo Merecimiento, aun al Sentenciar

En No Sólo Merecimiento: Una Teoría Republicana de la Justicia Penal, tratamos de establecer qué visión general del sistema de justicia penal sería apoyado por una filosofía republicana. Exploramos la forma que adoptaría un sistema de justicia penal si estuviera organizado para promover el objetivo de la libertad republicana. Definimos este objetivo como el de gozar de dominio. Argumentamos que es necesario pensar exhaustivamente sobre la forma que debería adoptar un sistema de justicia penal y que, en esta empresa, la aproximación republicana resulta de utilidad. En particular, argumentamos que este enfoque puede servirnos más que cualquier otro orientado por fines, como el utilitarismo, y también más que otro construido alrededor del límite de sólo asegurar merecimiento: aplicar un castigo proporcional a la gravedad de la ofensa y la culpabilidad del delincuente

Colloquium: Comparison of Astrophysical and Terrestrial Frequency Standards

We have re-analyzed the stability of pulse arrival times from pulsars and white dwarfs using several analysis tools for measuring the noise characteristics of sampled time and frequency data. We show that the best terrestrial artificial clocks substantially exceed the performance of astronomical sources as time-keepers in terms of accuracy (as defined by cesium primary frequency standards) and stability. This superiority in stability can be directly demonstrated over time periods up to two years, where there is high quality data for both. Beyond 2 years there is a deficiency of data for clock/clock comparisons and both terrestrial and astronomical clocks show equal performance being equally limited by the quality of the reference timescales used to make the comparisons. Nonetheless, we show that detailed accuracy evaluations of modern terrestrial clocks imply that these new clocks are likely to have a stability better than any astronomical source up to comparison times of at least hundreds of years. This article is intended to provide a correct appreciation of the relative merits of natural and artificial clocks. The use of natural clocks as tests of physics under the most extreme conditions is entirely appropriate; however, the contention that these natural clocks, particularly white dwarfs, can compete as timekeepers against devices constructed by mankind is shown to be doubtful.Comment: 9 pages, 2 figures; presented at the International Frequency Control Symposium, Newport Beach, Calif., June, 2010; presented at Pulsar Conference 2010, October 12th, Sardinia; accepted 13th September 2010 for publication in Reviews of Modern Physic

Lm-LLO-Based Immunotherapies and HPV-Associated Disease

HPV infection is a direct cause of neoplasia and malignancy. Cellular immunologic activity against cells expressing HPV E6 and E7 is sufficient to eliminate the presence of dysplastic or neoplastic tissue driven by HPV infection. Live attenuated Listeria monocytogenes- (Lm-) based immunotherapy (ADXS11-001) has been developed for the treatment of HPV-associated diseases. ADXS11-001 secretes an antigen-adjuvant fusion (Lm-LLO) protein consisting of a truncated fragment of the Lm protein listeriolysin O (LLO) fused to HPV-16 E7. In preclinical models, this construct has been found to stimulate immune responses and affect therapeutic outcome. ADXS11-001 is currently being evaluated in Phase 2 clinical trials for cervical intraepithelial neoplasia, cervical cancer, and HPV-positive head and neck cancer. The use of a live attenuated bacterium is a more complex and complete method of cancer immunotherapy, as over millennia Lm has evolved to infect humans and humans have evolved to prevent and reject this infection over millennia. This evolution has resulted in profound pathogen-associated immune mechanisms which are genetically conserved, highly efficacious, resistant to tolerance, and can be uniquely invoked using this novel platform technology