115 research outputs found
A Convex Framework for Optimal Investment on Disease Awareness in Social Networks
We consider the problem of controlling the propagation of an epidemic
outbreak in an arbitrary network of contacts by investing on disease awareness
throughout the network. We model the effect of agent awareness on the dynamics
of an epidemic using the SAIS epidemic model, an extension of the SIS epidemic
model that includes a state of "awareness". This model allows to derive a
condition to control the spread of an epidemic outbreak in terms of the
eigenvalues of a matrix that depends on the network structure and the
parameters of the model. We study the problem of finding the cost-optimal
investment on disease awareness throughout the network when the cost function
presents some realistic properties. We propose a convex framework to find
cost-optimal allocation of resources. We validate our results with numerical
simulations in a real online social network.Comment: IEEE GlobalSIP Symposium on Network Theor
Surface-plasmon-polariton wave propagation guided by a metal slab in a sculptured nematic thin film
Surface-plasmon-polariton~(SPP) wave propagation guided by a metal slab in a
periodically nonhomogeneous sculptured nematic thin film~(SNTF) was studied
theoretically. The morphologically significant planes of the SNTF on both sides
of the metal slab could either be aligned or twisted with respect to each
other. The canonical boundary-value problem was formulated, solved for SPP-wave
propagation, and examined to determine the effect of slab thickness on the
multiplicity and the spatial profiles of SPP waves. Decrease in slab thickness
was found to result in more intense coupling of two metal/SNTF interfaces. But
when the metal slab becomes thicker, the coupling between the two interfaces
reduces and SPP waves localize to one of the two interfaces. The greater the
coupling between the two metal/SNTF interfaces, the smaller is the phase speed.Comment: 17 page
Biologically Informed Individual-Based Network Model for Rift Valley Fever in the US and Evaluation of Mitigation Strategies
Citation: Scoglio, C. M., Bosca, C., Riad, M. H., Sahneh, F. D., Britch, S. C., Cohnstaedt, L. W., & Linthicum, K. J. (2016). Biologically Informed Individual-Based Network Model for Rift Valley Fever in the US and Evaluation of Mitigation Strategies. Plos One, 11(9), 26. doi:10.1371/journal.pone.0162759Rift Valley fever (RVF) is a zoonotic disease endemic in sub-Saharan Africa with periodic outbreaks in human and animal populations. Mosquitoes are the primary disease vectors; however, Rift Valley fever virus (RVFV) can also spread by direct contact with infected tissues. The transmission cycle is complex, involving humans, livestock, and multiple species of mosquitoes. The epidemiology of RVFV in endemic areas is strongly affected by climatic conditions and environmental variables. In this research, we adapt and use a network-based modeling framework to simulate the transmission of RVFV among hypothetical cattle operations in Kansas, US. Our model considers geo-located livestock populations at the individual level while incorporating the role of mosquito populations and the environment at a coarse resolution. Extensive simulations show the flexibility of our modeling framework when applied to specific scenarios to quantitatively evaluate the efficacy of mosquito control and livestock movement regulations in reducing the extent and intensity of RVF outbreaks in the United States
Computing ?-Stretch Paths in Drawings of Graphs
Let f be a drawing in the Euclidean plane of a graph G, which is understood to be a 1-dimensional simplicial complex. We assume that every edge of G is drawn by f as a curve of constant algebraic complexity, and the ratio of the length of the longest simple path to the the length of the shortest edge is poly(n). In the drawing f, a path P of G, or its image in the drawing ?=f(P), is ?-stretch if ? is a simple (non-self-intersecting) curve, and for every pair of distinct points p?P and q?P, the length of the sub-curve of ? connecting f(p) with f(q) is at most ?||f(p)-f(q)?, where ?.? denotes the Euclidean distance. We introduce and study the ?-stretch Path Problem (?SP for short), in which we are given a pair of vertices s and t of G, and we are to decide whether in the given drawing of G there exists a ?-stretch path P connecting s and t. The ?SP also asks that we output P if it exists.
The ?SP quantifies a notion of "near straightness" for paths in a graph G, motivated by gerrymandering regions in a map, where edges of G represent natural geographical/political boundaries that may be chosen to bound election districts. The notion of a ?-stretch path naturally extends to cycles, and the extension gives a measure of how gerrymandered a district is. Furthermore, we show that the extension is closely related to several studied measures of local fatness of geometric shapes.
We prove that ?SP is strongly NP-complete. We complement this result by giving a quasi-polynomial time algorithm, that for a given ?>0, ??O(poly(log |V(G)|)), and s,t?V(G), outputs a ?-stretch path between s and t, if a (1-?)?-stretch path between s and t exists in the drawing
Towards the Formalization of Fractional Calculus in Higher-Order Logic
Fractional calculus is a generalization of classical theories of integration
and differentiation to arbitrary order (i.e., real or complex numbers). In the
last two decades, this new mathematical modeling approach has been widely used
to analyze a wide class of physical systems in various fields of science and
engineering. In this paper, we describe an ongoing project which aims at
formalizing the basic theories of fractional calculus in the HOL Light theorem
prover. Mainly, we present the motivation and application of such formalization
efforts, a roadmap to achieve our goals, current status of the project and
future milestones.Comment: 9 page
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Time resolved spectroscopic investigation of SiD2 + D2: kinetic study
Silylenes (silanediyls) have made an important impact on organosilicon chemistry even if it is of more recent foundation than carbenes in organic chemistry and much less complete. These species are highly reactive intermediates. They play a central role in the chemical vapour deposition (CVD) of various silicon-containing thin films which have a technological importance in microelectronics as well as in the dry etching processes of silicon wafers. Spectroscopic methods have been developed to observe these species, a necessary pre-requisite to their direct monitoring. In this work, deuterated phenylsilane precursor, PhSiD3 was chosen for SiD2 because its analogue phenylsilane, PhSiH3 proved to be a good precursor for SiH2 and the high quality decay signals observed revealed that SiD2 be readily detected from PhSiD3 and that if other decomposition pathways (e.g. PhSiD + D2) are occurring, they do not effect measurements of the rate constants for SiD2. The absorption spectrum of SiD2 formed from the flash photolysis of a mixture of PhSiD3 and SF6 at 193nm were found in the region 17384-17391 cm-1 with strong band at 17387.07 cm-1. This single rotational line of pQ1 was chosen to monitor SiD2 removal. Time-resolved studies of SiD2 have been carried out to obtain rate constants for its bimolecular reactions with D2. The reactions were studied over the pressure range 5-100 Torr (in SF6 bath gas) at four temperatures in the range 298-498K. Single decay from 10 photolysis laser shots were averaged and found to give reasonable first-order kinetics fits. Second order kinetics were obtained by pressure dependence of the pseudo first order decay constants and substance D2 pressures within experimental error. The reaction was found to be weakly pressure dependent at all temperatures, consistent with a third-body mediated association process. In addition, SiH2+ H2 reaction is approximately ca. 60% faster than SiD2+D2 reaction. Theoretical extrapolations (using Lindemann-Hinshelwood model and Rice, Ramsperger, Kassel and Marcus (RRKM) theory) were also carried out and obtained data fitted the Arrhenius equations
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