1,519 research outputs found
Understanding Geopolitics from a Historical Perspective: The Burkina Faso Revolution, 1983-1987
No abstract provided
Photoluminescence from nanocrystalline graphite monofluoride
We synthesize and study the structural and optical properties of
nanocrystalline graphene monofluoride and graphite monofluoride, which are
carbon-based wide bandgap materials. Using laser excitations 2.41 - 5.08 eV, we
identify six emission modes of graphite monofluoride, spanning the visible
spectrum from red to violet. The energy and linewidth of the modes point to
defect-induced midgap states as the source of the photoemission. We discuss
possible candidates. Our findings open the window to electro-optical
applications of graphene fluoride.Comment: 11 pages including supporting information, 2 figure
Coding Teichmuller flow using veering triangulations
We develop the theory of veering triangulations on oriented surfaces adapted to
moduli spaces of half-translation surfaces. We use veering triangulations to give a coding of
the Teichmüller flow on connected components of strata of quadratic differentials. We prove
that this coding, given by a countable shift, has an approximate product structure and a
roof function with exponential tails. This makes it conducive to the study of the dynamics
of Teichmüller flow
Movie Editing and Cognitive Event Segmentation in Virtual Reality Video
Traditional cinematography has relied for over a century on a
well-established set of editing rules, called continuity editing, to create a
sense of situational continuity. Despite massive changes in visual content
across cuts, viewers in general experience no trouble perceiving the
discontinuous flow of information as a coherent set of events. However, Virtual
Reality (VR) movies are intrinsically different from traditional movies in that
the viewer controls the camera orientation at all times. As a consequence,
common editing techniques that rely on camera orientations, zooms, etc., cannot
be used. In this paper we investigate key relevant questions to understand how
well traditional movie editing carries over to VR. To do so, we rely on recent
cognition studies and the event segmentation theory, which states that our
brains segment continuous actions into a series of discrete, meaningful events.
We first replicate one of these studies to assess whether the predictions of
such theory can be applied to VR. We next gather gaze data from viewers
watching VR videos containing different edits with varying parameters, and
provide the first systematic analysis of viewers' behavior and the perception
of continuity in VR. From this analysis we make a series of relevant findings;
for instance, our data suggests that predictions from the cognitive event
segmentation theory are useful guides for VR editing; that different types of
edits are equally well understood in terms of continuity; and that spatial
misalignments between regions of interest at the edit boundaries favor a more
exploratory behavior even after viewers have fixated on a new region of
interest. In addition, we propose a number of metrics to describe viewers'
attentional behavior in VR. We believe the insights derived from our work can
be useful as guidelines for VR content creation
Spoligotype database of Mycobacterium tuberculosis: biogeographic distribution of shared types and epidemiologic and phylogenetic perspectives.
We give an update on the worldwide spoligotype database, which now contains 3,319 spoligotype patterns of Mycobacterium tuberculosis in 47 countries, with 259 shared types, i.e., identical spoligotypes shared by two or more patient isolates. The 259 shared types contained a total of 2,779 (84%) of all the isolates. Seven major genetic groups represented 37% of all clustered isolates. Two types (119 and 137) were found almost exclusively in the USA and accounted for 9% of clustered isolates. The remaining 1,517 isolates were scattered into 252 different spoligotypes. This database constitutes a tool for pattern comparison of M. tuberculosis clinical isolates for global epidemiologic studies and phylogenetic purposes
Influence of Xpand Nitric Oxide Reactor, L-Arginine Alpha-Ketoglutarate, and Caffeine Supplementation on Calf Muscle Re-Oxygenation During and after Acute Resistance Exercise
Xpand Nitric Oxide Reactor is a "cocktail" supplement proposed to improve skeletal muscle blood flow via arginine's effect on nitric oxide synthesis and vasodilation. Two other major ingredients, caffeine and creatine, cause vasoconstriction, which could potentially counteract the proposed hemodynamic effects of arginine. The purpose of this study was to examine the influence of Xpand Nitric Oxide Reactor on muscle re-oxygenation after resistance exercise compared to supplementation with constituent ingredients L-arginine alpha-ketoglutarate and caffeine. Nine recreationally active men (21±1y) performed 3 sets of 20 repetitions of seated single-leg calf raise at 60% 1-RM with 3 min rests. The same calf raise exercise was performed following 4 separate supplementation conditions: L-arginine alpha-ketoglutarate (AAKG), caffeine (CAFF), Xpand Nitric Oxide Reactor (XPAND), and placebo (PLAC). Soleus muscle re-oxygenation time was measured before, during, and immediately after exercise using near infrared spectroscopy. Supplementation with XPAND (0.43±0.03), AAKG (0.34±0.02), and CAFF (0.45±0.05) did not significantly affect muscle re-oxygenation halftime (minutes) compared to placebo (0.35±0.04). An arginine containing "cocktail" supplement did not affect skeletal muscle re-oxygenation after resistance exercise, possibly due to a wash-out effect caused by the multiple ingredients
NAMA3DS1-COSPAD1: Subjective video quality assessment database on coding conditions introducing freely available high quality 3D stereoscopic sequences
Research in stereoscopic 3D coding, transmission and subjective assessment methodology depends largely on the availability of source content that can be used in cross-lab evaluations. While several studies have already been presented using proprietary content, comparisons between the studies are difficult since discrepant contents are used. Therefore in this paper, a freely available dataset of high quality Full-HD stereoscopic sequences shot with a semiprofessional 3D camera is introduced in detail. The content was designed to be suited for usage in a wide variety of applications, including high quality studies. A set of depth maps was calculated from the stereoscopic pair. As an application example, a subjective assessment has been performed using coding and spatial degradations. The Absolute Category Rating with Hidden Reference method was used. The observers were instructed to vote on video quality only. Results of this experiment are also freely available and will be presented in this paper as a first step towards objective video quality measurement for 3DTV
Ancient Origin and Gene Mosaicism of the Progenitor of Mycobacterium tuberculosis
The highly successful human pathogen Mycobacterium tuberculosis has an extremely low level of genetic variation, which suggests that the entire population resulted from clonal expansion following an evolutionary bottleneck around 35,000 y ago. Here, we show that this population constitutes just the visible tip of a much broader progenitor species, whose extant representatives are human isolates of tubercle bacilli from East Africa. In these isolates, we detected incongruence among gene phylogenies as well as mosaic gene sequences, whose individual elements are retrieved in classical M. tuberculosis. Therefore, despite its apparent homogeneity, the M. tuberculosis genome appears to be a composite assembly resulting from horizontal gene transfer events predating clonal expansion. The amount of synonymous nucleotide variation in housekeeping genes suggests that tubercle bacilli were contemporaneous with early hominids in East Africa, and have thus been coevolving with their human host much longer than previously thought. These results open novel perspectives for unraveling the molecular bases of M. tuberculosis evolutionary success
An Exploratory Factor Analysis of Climate Friendly Purchasing Choices
Climate change is negatively affecting the environment and all its inhabitants. People\u27s increased awareness have made them more willing to adopt more climate friendly purchasing choices. The Climate Change Action Inventory measures how often individuals take actions that can reduce climate change. We focused on the Climate Friendly Purchasing Choices Domain. We conducted an exploratory factor analysis of the Climate Friendly Purchasing Domain to help us examine the factor structure.https://digitalscholarship.unlv.edu/durep_posters/1122/thumbnail.jp
- …