21 research outputs found
Bursts of vertex activation and epidemics in evolving networks
The dynamic nature of contact patterns creates diverse temporal structures. In particular, empirical studies have shown that contact patterns follow heterogeneous inter-event time intervals, meaning that periods of high activity are followed by long periods of inactivity. To investigate the impact of these heterogeneities in the spread of infection from a theoretical perspective, we propose a stochastic model to generate temporal networks where vertices make instantaneous contacts following heterogeneous inter-event intervals, and may leave and enter the system. We study how these properties affect the prevalence of an infection and estimate , the number of secondary infections of an infectious individual in a completely susceptible population, by modeling simulated infections (SI and SIR) that co-evolve with the network structure. We find that heterogeneous contact patterns cause earlier and larger epidemics in the SIR model in comparison to homogeneous scenarios for a vast range of parameter values, while smaller epidemics may happen in some combinations of parameters. In the case of SI and heterogeneous patterns, the epidemics develop faster in the earlier stages followed by a slowdown in the asymptotic limit. For increasing vertex turnover rates, heterogeneous patterns generally cause higher prevalence in comparison to homogeneous scenarios with the same average inter-event interval. We find that is generally higher for heterogeneous patterns, except for sufficiently large infection duration and transmission probability
The rank reversal problem in multi-criteria decision making : a literature review
Despite the importance of multicriteria decision-making (MCDM) techniques for constructing effective decision models, there are many criticisms due to the occurrence of a problem called rank reversal. Nevertheless, there is a lack of a systematic literature review on this important subject which involves different methods. This study reviews the pertinent literature on rank reversal, based on 130 related articles published from 1980 to 2015 in international journals, which were gathered and analyzed according to the following perspectives: multicriteria technique, year and journal in which the papers were published, co-authorship network, rank reversal types, and research goal. Thus our survey provides recommendations for future research, besides useful information and knowledge regarding rank reversal in the MCDM field
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Searches for rare B-s(0) and B-0 decays into four muons
Searches for rare and decays into four muons are performed
using proton-proton collision data recorded by the LHCb experiment,
corresponding to an integrated luminosity of 9 . Direct decays
and decays via light scalar and resonances are considered. No evidence
for the six decays searched for is found and upper limits at the 95% confidence
level on their branching fractions ranging between and
are set
First measurement of the ZâÎŒ+ÎŒâ angular coefficients in the forward region of pp collisions at âs = 13 TeV
The first study of the angular distribution of
Ό
+
Ό
â
pairs produced in the forward rapidity region via the Drell-Yan reaction
p
p
â
Îł
â
/
Z
+
X
â
â
+
â
â
+
X
is presented, using data collected with the LHCb detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of
5.1
â
â
fb
â
1
. The coefficients of the five leading terms in the angular distribution are determined as a function of the dimuon transverse momentum and rapidity. The results are compared to various theoretical predictions of the
Z
-boson production mechanism and can also be used to probe transverse-momentum-dependent parton distributions within the proton