Computability of the causal boundary by using isocausality

Recently, a new viewpoint on the classical c-boundary in Mathematical Relativity has been developed, the relations of this boundary with the conformal one and other classical boundaries have been analyzed, and its computation in some classes of spacetimes, as the standard stationary ones, has been carried out. In the present paper, we consider the notion of isocausality given by Garc\'ia-Parrado and Senovilla, and introduce a framework to carry out isocausal comparisons with standard stationary spacetimes. As a consequence, the qualitative behavior of the c-boundary (at the three levels: point set, chronology and topology) of a wide class of spacetimes, is obtained.Comment: 44 pages, 5 Figures, latex. Version with minor changes and the inclusion of Figure

Quantum mechanical analysis of the elastic propagation of electrons in the Au/Si system: application to Ballistic Electron Emission Microscopy

We present a Green's function approach based on a LCAO scheme to compute the elastic propagation of electrons injected from a STM tip into a metallic film. The obtained 2D current distribution in real and reciprocal space furnish a good representation of the elastic component of Ballistic Electron Emission Microscopy (BEEM) currents. Since this component accurately approximates the total current in the near threshold region, this procedure allows --in contrast to prior analyses-- to take into account effects of the metal band structure in the modeling of these experiments. The Au band structure, and in particular its gaps appearing in the [111] and [100] directions provides a good explanation for the previously irreconcilable results of nanometric resolution and similarity of BEEM spectra on both Au/Si(111) and Au/Si(100).Comment: 12 pages, 9 postscript figures, revte

TRUMPS SOCIAL MEDIA – THE FIRST 100 DAYS OF HIS PRESIDENCY: A CONTENT ANALYSIS

More than any time in history technology allows politicians to directly reach large audiences to increase interaction. Modern social media permits information to be more accessible, direct, and permanent. Politicians can address audiences more frequently and directly through mobile devices - a tactic which creates a perception of immediacy unseen in past political climates. Specifically, Twitter grants unfiltered communication with users, while bypassing established mainstream media. The use of Twitter politically was first revolutionized by Barak Obama. Donald Trump’s use of Twitter has elevated this social media platform to an unheard-of level. A content analysis was conducted on President Donald Trump’s Tweets from his first 100 days in office. The results indicate that the majority of these Tweets can be separated into the Burkeian categories of Identity and Division. A discussion of the substance of these Tweets, the political use of social media, and specifically President Trump’s embracing of Twitter ensues

Hot electron transport in Ballistic Electron Emission Spectroscopy: band structure effects and k-space currents

Using a Green's function approach, we investigate band structure effects in the BEEM current distribution in reciprocal space. In the elastic limit, this formalism provides a 'parameter free' solution to the BEEM problem. At low temperatures, and for thin metallic layers, the elastic approximation is enough to explain the experimental I(V) curves at low voltages. At higher voltages inelastic effects are approximately taken into account by introducing an effective RPA-electron lifetime, much in similarity with LEED theory. For thick films, however, additional damping mechanisms are required to obtain agreement with experiment.Comment: 4 pages, 3 postscript figures, revte

A metagenomic assessment of the bacteria associated with Lucilia sericata and Lucilia cuprina (Diptera: Calliphoridae)

Lucilia Robineau-Desvoidy (Diptera: Calliphoridae) is a blow fly genus of forensic, medical, veterinary, and agricultural importance. This genus is also famous because of its beneficial uses in maggot debridement therapy (MDT). Although the genus is of considerable economic importance, our knowledge about microbes associated with these flies and how these bacteria are horizontally and trans-generationally transmitted is limited. In this study, we characterized bacteria associated with different life stages of Lucilia sericata (Meigen) and Lucilia cuprina(Wiedemann) and in the salivary gland of L. sericata by using 16S rDNA 454 pyrosequencing. Bacteria associated with the salivary gland of L. sericata were also characterized using light and transmission electron microscopy (TEM). Results from this study suggest that the majority of bacteria associated with these flies belong to phyla Proteobacteria, Firmicutes, andBacteroidetes, and most bacteria are maintained intragenerationally, with a considerable degree of turnover from generation to generation. In both species, second-generation eggs exhibited the highest bacterial phylum diversity (20 % genetic distance) than other life stages. The Lucilia sister species shared the majority of their classified genera. Of the shared bacterial genera, Providencia, Ignatzschineria, Lactobacillus, Lactococcus, Vagococcus, Morganella, and Myroides were present at relatively high abundances. Lactobacillus, Proteus,Diaphorobacter, and Morganella were the dominant bacterial genera associated with a survey of the salivary gland of L. sericata. TEM analysis showed a sparse distribution of both Gram-positive and Gram-negative bacteria in the salivary gland of L. sericata. There was more evidence for horizontal transmission of bacteria than there was for trans-generational inheritance. Several pathogenic genera were either amplified or reduced by the larval feeding on decomposing liver as a resource. Overall, this study provides information on bacterial communities associated with different life stages of Lucilia and their horizontal and trans-generational transmission, which may help in the development of better vector-borne disease management and MDT methods

On the completeness of impulsive gravitational wave space-times

We consider a class of impulsive gravitational wave space-times, which generalize impulsive pp-waves. They are of the form $M=N\times\mathbb{R}^2_1$, where $(N,h)$ is a Riemannian manifold of arbitrary dimension and $M$ carries the line element $ds^2=dh^2+ 2dudv+f(x)\delta(u)du^2$ with $dh^2$ the line element of $N$ and $\delta$ the Dirac measure. We prove a completeness result for such space-times $M$ with complete Riemannian part $N$.Comment: 13 pages, minor changes suggested by the referee

Pattern matching and pattern discovery algorithms for protein topologies

We describe algorithms for pattern matching and pattern learning in TOPS diagrams (formal descriptions of protein topologies). These problems can be reduced to checking for subgraph isomorphism and finding maximal common subgraphs in a restricted class of ordered graphs. We have developed a subgraph isomorphism algorithm for ordered graphs, which performs well on the given set of data. The maximal common subgraph problem then is solved by repeated subgraph extension and checking for isomorphisms. Despite the apparent inefficiency such approach gives an algorithm with time complexity proportional to the number of graphs in the input set and is still practical on the given set of data. As a result we obtain fast methods which can be used for building a database of protein topological motifs, and for the comparison of a given protein of known secondary structure against a motif database

Impact of Interprofessional Student Teams at a Remote Area Medical Event in Rural Appalachia

Introduction: Education in interprofessional collaboration is vital to expand healthcare access, especially in areas of higher disparity. To address this need, interprofessional faculty collaborators incorporated undergraduate and graduate health profession students into teams at an annual Remote Area Medical event in rural Appalachia between 2017 and 2020. Purpose: This article evaluates the impact of an interprofessional student teams model on both patient care experience and students’ interprofessional collaboration attitudes and behaviors. Methods: Student volunteers completed pre- and post-event surveys containing questions about demographics, open-ended questions, and questions from two instruments: the Student Perceptions of Interprofessional Clinical Education-Revised Instrument, Version 2 (SPICE-R2) and the Interprofessional Collaborative Competency Attainment Scale-Revised (ICCAS-R). Quantitative data were analyzed statistically; qualitative data thematically. Tally forms collected patient care interventions that were compared to regional health disparities. Two years of survey data and four years of intervention data were analyzed. Results: There was an increase (p \u3c 0.001) in the post-event survey SPICE-R2 factors (teamwork, healthcare outcomes, and roles and responsibilities) in 2020 but not in 2019. ICCAS-R mean post-event composite scores increased (p \u3c 0.05) in both 2019 and 2020. Qualitative coding of open-ended responses revealed interprofessional competency themes and provided event feedback. Over 5,900 health-disparity-focused interventions were completed between 2017 and 2020. Implications: Students participating in interprofessional teams demonstrate changes in attitudes towards the interprofessional approach to care, an improved ability to collaborate interprofessionally, and a positive impact on patient care interventions. The findings allow educators to understand how experiential interprofessional education influences students’ interprofessional attitudes and beliefs while benefitting patient care