604 research outputs found
A note on uniform power connectivity in the SINR model
In this paper we study the connectivity problem for wireless networks under
the Signal to Interference plus Noise Ratio (SINR) model. Given a set of radio
transmitters distributed in some area, we seek to build a directed strongly
connected communication graph, and compute an edge coloring of this graph such
that the transmitter-receiver pairs in each color class can communicate
simultaneously. Depending on the interference model, more or less colors,
corresponding to the number of frequencies or time slots, are necessary. We
consider the SINR model that compares the received power of a signal at a
receiver to the sum of the strength of other signals plus ambient noise . The
strength of a signal is assumed to fade polynomially with the distance from the
sender, depending on the so-called path-loss exponent .
We show that, when all transmitters use the same power, the number of colors
needed is constant in one-dimensional grids if as well as in
two-dimensional grids if . For smaller path-loss exponents and
two-dimensional grids we prove upper and lower bounds in the order of
and for and
for respectively. If nodes are distributed
uniformly at random on the interval , a \emph{regular} coloring of
colors guarantees connectivity, while colors are required for any coloring.Comment: 13 page
Artificial inoculation on plants and banana leaf pieces with Mycosphaerella spp., responsible for Sigatoka leaf spot diseases
Ce protocole vise (i) à analyser la nature des interactions hÎtes-parasites (résistance ou sensibilité), (ii) à étudier la variabilité de la pathogénicité de différentes populations pathogÚnes (intra/interspécifiques) quant à leur virulence et leur agressivité mesurées à partir d''inoculation artificielle avec Mycosphaerella fijiensis ou Mycosphaerella musicola sur des plants et des morceaux de feuille de bananier. Le principe, les principaux avantages, le matériel végétal de départ et le temps nécessaire de la méthode sont présentés. Matériel et méthodes. Le matériel de laboratoire nécessaire et le détail des seize étapes de réalisation du protocole (préparation de l'inoculum conidial, inoculation artificielle sur des plants de bananier, et inoculation artificielle sur des morceaux de feuille de bananier) sont décrits. Des problÚmes potentiels sont évoqués. Résultats. Des symptÎmes-types de la maladie sont obtenus aprÚs inoculation artificielle (Résumé d'auteur
Growth, Structure and Properties of Epitaxial Thin Films of First Principles Predicted Multiferroic Bi2FeCrO6
We report the structural and physical properties of epitaxial Bi2FeCrO6 thin
films on epitaxial SrRuO3 grown on (100)-oriented SrTiO3 substrates by pulsed
laser ablation. The 300 nm thick films exhibit both ferroelectricity and
magnetism at room temperature with a maximum dielectric polarization of 2.8
microC/cm2 at Emax = 82 kV/cm and a saturated magnetization of 20 emu/cc
(corresponding to ~ 0.26 Bohr magneton per rhombohedral unit cell), with
coercive fields below 100 Oe. Our results confirm the predictions made using
ab-initio calculations about the existence of multiferroic properties in
Bi2FeCrO6.Comment: Manuscript accepted for publication in Applied Physics Letters (in
press). The paper consists of 1619 words, 13 references and 3 figure
Dual Stimuli Response Frequency and Stimulus Choice of the African Clawed Frog, Xenopus laevis, when presented with two stimuli
This preliminary study examines responses of African Clawed Frogs to simultaneous presentation of two stimuli. Frogs were tested in a round arena with water 4 cm deep. Four stimulus rods driven via computer-controlled stepper motors were concealed in a screen suspended above the water. These rods could present a lateral line stimulus, a visual stimulus, or a combination of both. Overall, reactions and no reactions were evenly distributed--51.1% and 48.9%, respectively. Frogs responded more frequently to rostral than caudal stimuli (chi-squared 20.8, df=11, p \u3c 0.04). Frogs reacted more to stimuli between -90° and 90°. Turn angle depended linearly on stimulus angle (e.g., Turn angle = 0.44 + 0.64 x Stimulus angle; pslope \u3c 0.0001; R2adj = 69.5%). (The distributions of stimulus angles appear slightly skewed as often the same stimulus rod was retested after the frog responded and partially oriented towards it, prompting a second test with smaller angles.) Two stimuli did not elicit more responses than one stimuli (P=0.25). The frogsâ choice of stimulus depended primarily on stimulus proximity and angle, not stimulus type. When presented with two stimuli, the frog chose the nearer stimulus and the more rostral stimulus (p \u3c 0.0001). The largest factor in predicting the frogâs choice of stimuli seems to be the linear distance from the stimuli to the frog.https://engagedscholarship.csuohio.edu/u_poster_2015/1009/thumbnail.jp
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