541 research outputs found
Non-systemic transmission of tick-borne diseases: a network approach
Tick-Borne diseases can be transmitted via non-systemic (NS) transmission.
This occurs when tick gets the infection by co-feeding with infected ticks on
the same host resulting in a direct pathogen transmission between the vectors,
without infecting the host. This transmission is peculiar, as it does not
require any systemic infection of the host. The NS transmission is the main
efficient transmission for the persistence of the Tick-Borne Encephalitis virus
in nature. By describing the heterogeneous ticks aggregation on hosts through a
\hyphenation{dynamical} bipartite graphs representation, we are able to
mathematically define the NS transmission and to depict the epidemiological
conditions for the pathogen persistence. Despite the fact that the underlying
network is largely fragmented, analytical and computational results show that
the larger is the variability of the aggregation, and the easier is for the
pathogen to persist in the population.Comment: 15 pages, 4 figures, to be published in Communications in Nonlinear
Science and Numerical Simulatio
Firsthand Opiates Abuse on Social Media: Monitoring Geospatial Patterns of Interest Through a Digital Cohort
In the last decade drug overdose deaths reached staggering proportions in the
US. Besides the raw yearly deaths count that is worrisome per se, an alarming
picture comes from the steep acceleration of such rate that increased by 21%
from 2015 to 2016. While traditional public health surveillance suffers from
its own biases and limitations, digital epidemiology offers a new lens to
extract signals from Web and Social Media that might be complementary to
official statistics. In this paper we present a computational approach to
identify a digital cohort that might provide an updated and complementary view
on the opioid crisis. We introduce an information retrieval algorithm suitable
to identify relevant subspaces of discussion on social media, for mining data
from users showing explicit interest in discussions about opioid consumption in
Reddit. Moreover, despite the pseudonymous nature of the user base, almost 1.5
million users were geolocated at the US state level, resembling the census
population distribution with a good agreement. A measure of prevalence of
interest in opiate consumption has been estimated at the state level, producing
a novel indicator with information that is not entirely encoded in the standard
surveillance. Finally, we further provide a domain specific vocabulary
containing informal lexicon and street nomenclature extracted by user-generated
content that can be used by researchers and practitioners to implement novel
digital public health surveillance methodologies for supporting policy makers
in fighting the opioid epidemic.Comment: Proceedings of the 2019 World Wide Web Conference (WWW '19
Optimizing surveillance for livestock disease spreading through animal movements
The spatial propagation of many livestock infectious diseases critically
depends on the animal movements among premises; so the knowledge of movement
data may help us to detect, manage and control an outbreak. The identification
of robust spreading features of the system is however hampered by the temporal
dimension characterizing population interactions through movements. Traditional
centrality measures do not provide relevant information as results strongly
fluctuate in time and outbreak properties heavily depend on geotemporal initial
conditions. By focusing on the case study of cattle displacements in Italy, we
aim at characterizing livestock epidemics in terms of robust features useful
for planning and control, to deal with temporal fluctuations, sensitivity to
initial conditions and missing information during an outbreak. Through spatial
disease simulations, we detect spreading paths that are stable across different
initial conditions, allowing the clustering of the seeds and reducing the
epidemic variability. Paths also allow us to identify premises, called
sentinels, having a large probability of being infected and providing critical
information on the outbreak origin, as encoded in the clusters. This novel
procedure provides a general framework that can be applied to specific
diseases, for aiding risk assessment analysis and informing the design of
optimal surveillance systems.Comment: Supplementary Information at
https://sites.google.com/site/paolobajardi/Home/archive/optimizing_surveillance_ESM_l.pdf?attredirects=
The Topological Invariant Approach: From Cosmology to Complex Biological Systems
This thesis addresses applications of topological invariants in the context of gravity, electromagnetism and complex systems. Specifically, in Chapters 3-8, different theories of gravity involving the Gauss–Bonnet term are discussed, as well as f(G) gravity, scalar-tensor theories and non-local theories. In all cases, after selecting viable models by symmetry considerations, field equation solutions are provided in cosmological and spherically symmetric backgrounds. In Chapter 9, basic foundations of Chern-Simons theory are reviewed, as in Chapters 10-13 the theory is then applied to the gravitational interaction, electromagnetism and complex biological systems. This latter application mainly aims to predict the effect of the induced mutations occurring in DNA/RNA sequences
Interplay of network dynamics and ties heterogeneity on spreading dynamics
The structure of a network dramatically affects the spreading phenomena
unfolding upon it. The contact distribution of the nodes has long been
recognized as the key ingredient in influencing the outbreak events. However,
limited knowledge is currently available on the role of the weight of the edges
on the persistence of a pathogen. At the same time, recent works showed a
strong influence of temporal network dynamics on disease spreading. In this
work we provide an analytical understanding, corroborated by numerical
simulations, about the conditions for infected stable state in weighted
networks. In particular, we reveal the role of heterogeneity of edge weights
and of the dynamic assignment of weights on the ties in the network in driving
the spread of the epidemic. In this context we show that when weights are
dynamically assigned to ties in the network an heterogeneous distribution is
able to hamper the diffusion of the disease, contrary to what happens when
weights are fixed in time.Comment: 10 pages, 10 figure
Equivalence of non-minimally coupled cosmologies by Noether symmetries
We discuss non-minimally coupled cosmologies involving different geometric
invariants. Specifically, actions containing a non-minimally coupled scalar
field to gravity described, in turn, by curvature, torsion and Gauss--Bonnet
scalars are considered. We show that couplings, potentials and kinetic terms
are determined by the existence of Noether symmetries which, moreover, allows
to reduce and solve dynamics. The main finding of the paper is that different
non-minimally coupled theories, presenting the same Noether symmetries, are
dynamically equivalent. In other words, Noether symmetries are a selection
criterion to compare different theories of gravity.Comment: 16 pages. Accepted for publication in "International Journal of
Modern Physics D
Late-time constraints on modified Gauss-Bonnet cosmology
In this paper, we consider a gravitational action containing a combination of
the Ricci scalar, , and the topological Gauss--Bonnet term, .
Specifically, we study the cosmological features of a particular class of
modified gravity theories selected by symmetry considerations, namely the
model. In the context of a spatially flat, homogeneous
and isotropic background, we show that the currently observed acceleration of
the Universe can be addressed through geometry, hence avoiding \emph{de facto}
the shortcomings of the cosmological constant. We thus present a strategy to
numerically solve the Friedmann equations in presence of pressureless matter
and obtain the redshift behavior of the Hubble expansion rate. Then, to check
the viability of the model, we place constraints on the free parameters of the
theory by means of a Bayesian Monte Carlo method applied to late-time cosmic
observations. Our results show that the model is capable of mimicking
the low-redshift behavior of the standard CDM model, though
substantial differences emerge when going toward high redshifts, leading to the
absence of a standard matter-dominated epoch. Finally, we investigate the
energy conditions and show that, under suitable choices for the values of the
cosmographic parameters, they are all violated when considering the mean value
of obtained from our analysis, as occurs in the case of a dark fluid.Comment: 10 pages, 3 figures, 1 tabl
Noether Symmetries and Quantum Cosmology in Extended Teleparallel Gravity
We apply the Noether Symmetry Approach to point-like teleparallel Lagrangians
in view to derive minisuperspaces suitable for Quantum Cosmology. Adopting the
Arnowitt-Deser-Misner formalism, we find out related Wave Functions of the
Universe. Specifically, by means of appropriate changes of variables suggested
by the existence of Noether symmetries, it is possible to obtain the
cosmological Hamiltonians whose solutions are classical trajectories
interpretable as observable universes.Comment: 15 Pages, 1 figur
Minisuperspace quantum cosmology in gravity
symmetric-teleparallel gravity is considered in view of Quantum
Cosmology. Specifically, we derive cosmological equations for models and
then investigate the related energy conditions. In the minisuperspace
formalism, the point-like Hamiltonian is taken into account. In this
framework, we obtain and solve the Wheeler-De Witt equation, thus finding the
Wave Function of the Universe in different cases. We show that the Hartle
Criterion can be applied and classical observable universes occur.Comment: 17 pages, 2 Figures. Accepted for publication in EPJ
Contribuciones de la educación artística a la construcción de la identidad profesional docente: competencias básicas y comunicativas.
This article deals with theprofessional identityof teachersand howthe artscancontributetoits development.We analyze theprofessional competencesof teachersand the importance of communication, emphasizing therelevance ofreflective practice andsignificant learningina collaborative environmentthat take into accountsocial interactionand negotiationofknowledge.The arts disciplines promote social tools that allow people to build their identities, such as verbal and nonverbal communication, critical thinking and the exchange of experiences.Este artículo trata la identidad profesional docente y como las disciplinas artísticas contribuyena su desarrollo. Se analizan las competencias profesionales y la importancia de la comunicación, enfatizando la relevancia de la práctica reflexiva y del aprendizaje significativo en un entorno colaborativo que pone en valor las interacciones sociales y la negociación de los conocimientos. Las disciplinas artísticas favorecenherramientas sociales que permiten al individuo construir su propia identidad, como la comunicación verbal y no verbal, el espíritu crítico y el intercambio de experiencias
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