1,528 research outputs found
Predicting the extinction of Ebola spreading in Liberia due to mitigation strategies
The Ebola virus is spreading throughout West Africa and is causing thousands of deaths. In order to quantify the effectiveness of different strategies for controlling the spread, we develop a mathematical model in which the propagation of the Ebola virus through Liberia is caused by travel between counties. For the initial months in which the Ebola virus spreads, we find that the arrival times of the disease into the counties predicted by our model are compatible with World Health Organization data, but we also find that reducing mobility is insufficient to contain the epidemic because it delays the arrival of Ebola virus in each county by only a few weeks. We study the effect of a strategy in which safe burials are increased and effective hospitalisation instituted under two scenarios: (i) one implemented in mid-July 2014 and (ii) one in mid-August—which was the actual time that strong interventions began in Liberia. We find that if scenario (i) had been pursued the lifetime of the epidemic would have been three months shorter and the total number of infected individuals 80% less than in scenario (ii). Our projection under scenario (ii) is that the spreading will stop by mid-spring 2015.H.E.S. thanks the NSF (grants CMMI 1125290 and CHE-1213217) and the Keck Foundation for financial support. L.D.V. and L.A.B. wish to thank to UNMdP and FONCyT (Pict 0429/2013) for financial support. (CMMI 1125290 - NSF; CHE-1213217 - NSF; Keck Foundation; UNMdP; Pict 0429/2013 - FONCyT)Published versio
Role of bridge nodes in epidemic spreading: Different regimes and crossovers
Power-law behaviors are common in many disciplines, especially in network
science. Real-world networks, like disease spreading among people, are more
likely to be interconnected communities, and show richer power-law behaviors
than isolated networks. In this paper, we look at the system of two communities
which are connected by bridge links between a fraction of bridge nodes, and
study the effect of bridge nodes to the final state of the
Susceptible-Infected-Recovered model, by mapping it to link percolation. By
keeping a fixed average connectivity, but allowing different transmissibilities
along internal and bridge links, we theoretically derive different power-law
asymptotic behaviors of the total fraction of the recovered in the final
state as goes to zero, for different combinations of internal and bridge
link transmissibilities. We also find crossover points where follows
different power-law behaviors with on both sides when the internal
transmissibility is below but close to its critical value, for different bridge
link transmissibilities. All of these power-law behaviors can be explained
through different mechanisms of how finite clusters in each community are
connected into the giant component of the whole system, and enable us to pick
effective epidemic strategies and to better predict their impacts
Structural crossover of polymers in disordered media
We present a unified scaling theory for the structural behavior of polymers
embedded in a disordered energy substrate. An optimal polymer configuration is
defined as the polymer configuration that minimizes the sum of interacting
energies between the monomers and the substrate. The fractal dimension of the
optimal polymer in the limit of strong disorder (SD) was found earlier to be
larger than the fractal dimension in weak disorder (WD). We introduce a scaling
theory for the crossover between the WD and SD limits. For polymers of various
sizes in the same disordered substrate we show that polymers with a small
number of monomers, N << N*, will behave as in SD, while large polymers with
length N >> N* will behave as in WD. This implies that small polymers will be
relatively more compact compared to large polymers even in the same substrate.
The crossover length N* is a function of \nu and a, where \nu is the
percolation correlation length exponent and a is the parameter which controls
the broadness of the disorder. Furthermore, our results show that the crossover
between the strong and weak disorder limits can be seen even within the same
polymer configuration. If one focuses on a segment of size n << N* within a
long polymer (N >> N*) that segment will have a higher fractal dimension
compared to a segment of size n >> N*
Pengujian Koalisi Likuiditas, Solvabilitas dan Profitabilitas terhadap Harga Saham (Perusahaan Sektor Pertanian Terdaftar di ISSI)
This research was aimed to find out the coalition liquidity, solvency, and profitability testing of stock prices. The population in this research was agricultural companies listed in the ISSI registered in the period 2013-2016 as many as 14 companies. The sample used in this research were only six companies by using sampling technique based on purposive sampling. The results showed that the variables CR, and DAR partially had no significant effect on stock prices. For ROE variable partially had a significant positive effect on stock price. While the simultaneous variables CR, DAR, and ROE had significant influences on stock prices. And based on test results, determination coefficient showed that Adjusted R2 value in regression model of 47% while the remaining 53% was influenced by other factors not included in the regression model
Effect of Disorder Strength on Optimal Paths in Complex Networks
We study the transition between the strong and weak disorder regimes in the
scaling properties of the average optimal path in a disordered
Erd\H{o}s-R\'enyi (ER) random network and scale-free (SF) network. Each link
is associated with a weight , where is a
random number taken from a uniform distribution between 0 and 1 and the
parameter controls the strength of the disorder. We find that for any
finite , there is a crossover network size at which the transition
occurs. For the scaling behavior of is in the
strong disorder regime, with for ER networks and
for SF networks with , and for SF networks with . For the scaling behavior is in the weak disorder regime, with for ER networks and SF networks with . In order to
study the transition we propose a measure which indicates how close or far the
disordered network is from the limit of strong disorder. We propose a scaling
ansatz for this measure and demonstrate its validity. We proceed to derive the
scaling relation between and . We find that for ER
networks and for SF networks with , and for SF networks with .Comment: 6 pages, 6 figures. submitted to Phys. Rev.
Radiative Corrections to Neutrino Deep Inelastic Scattering Revisited
Radiative corrections to neutrino deep inelastic scattering are revisited.
One-loop electroweak corrections are re-calculated within the automatic SANC
system. Terms with mass singularities are treated including higher order
leading logarithmic corrections. Scheme dependence of corrections due to weak
interactions is investigated. The results are implemented into the data
analysis of the NOMAD experiment. The present theoretical accuracy in
description of the process is discussed.Comment: 19 pages, two figures are added, discussion of theoretical
uncertainties is extende
The polyphenols resveratrol and epigallocatechin-3-gallate restore the severe impairment of mitochondria in hippocampal progenitor cells from a Down syndrome mouse model.
Mitochondrial dysfunctions critically impair nervous system development and are potentially involved in the pathogenesis of various neurodevelopmental disorders, including Down syndrome (DS), the most common genetic cause of intellectual disability. Previous studies from our group demonstrated impaired mitochondrial activity in peripheral cells from DS subjects and the efficacy of epigallocatechin-3-gallate (EGCG) - a natural polyphenol major component of green tea - to counteract the mitochondrial energy deficit. In this study, to gain insight into the possible role of mitochondria in DS intellectual disability, mitochondrial functions were analyzed in neural progenitor cells (NPCs) isolated from the hippocampus of Ts65Dn mice, a widely used model of DS which recapitulates many major brain structural and functional phenotypes of the syndrome, including impaired hippocampal neurogenesis. We found that, during NPC proliferation, mitochondrial bioenergetics and mitochondrial biogenic program were strongly compromised in Ts65Dn cells, but not associated with free radical accumulation. These data point to a central role of mitochondrial dysfunction as an inherent feature of DS and not as a consequence of cell oxidative stress. Further, we disclose that, besides EGCG, also the natural polyphenol resveratrol, which displays a neuroprotective action in various human diseases but never tested in DS, restores oxidative phosphorylation efficiency and mitochondrial biogenesis, and improves proliferation of NPCs. These effects were associated with the activation of PGC-1α/Sirt1/AMPK axis by both polyphenols. This research paves the way for using nutraceuticals as a potential therapeutic tool in preventing or managing some energy deficit-associated DS clinical manifestations
- …