597 research outputs found
Finite size corrections to disordered Ising models on Random Regular Graphs
We derive the analytical expression for the first finite size correction to
the average free energy of disordered Ising models on random regular graphs.
The formula can be physically interpreted as a weighted sum over all non
self-intersecting loops in the graph, the weight being the free-energy shift
due to the addition of the loop to an infinite tree
Loop expansion around the Bethe approximation through the -layer construction
For every physical model defined on a generic graph or factor graph, the
Bethe -layer construction allows building a different model for which the
Bethe approximation is exact in the large limit and it coincides with the
original model for . The perturbative series is then expressed by a
diagrammatic loop expansion in terms of so-called fat-diagrams. Our motivation
is to study some important second-order phase transitions that do exist on the
Bethe lattice but are either qualitatively different or absent in the
corresponding fully connected case. In this case the standard approach based on
a perturbative expansion around the naive mean field theory (essentially a
fully connected model) fails. On physical grounds, we expect that when the
construction is applied to a lattice in finite dimension there is a small
region of the external parameters close to the Bethe critical point where
strong deviations from mean-field behavior will be observed. In this region,
the expansion for the corrections diverges and it can be the starting
point for determining the correct non-mean-field critical exponents using
renormalization group arguments. In the end, we will show that the critical
series for the generic observable can be expressed as a sum of Feynman diagrams
with the same numerical prefactors of field theories. However, the contribution
of a given diagram is not evaluated associating Gaussian propagators to its
lines as in field theories: one has to consider the graph as a portion of the
original lattice, replacing the internal lines with appropriate one-dimensional
chains, and attaching to the internal points the appropriate number of
infinite-size Bethe trees to restore the correct local connectivity of the
original model
Linked Data approach for selection process automation in Systematic Reviews
Background: a systematic review identifies, evaluates and synthesizes the available literature on a given topic using scientific and repeatable methodologies. The significant workload required and the subjectivity bias could affect results. Aim: semi-automate the selection process to reduce the amount of manual work needed and the consequent subjectivity bias. Method: extend and enrich the selection of primary studies using the existing technologies in the field of Linked Data and text mining. We define formally the selection process and we also develop a prototype that implements it. Finally, we conduct a case study that simulates the selection process of a systematic literature published in literature. Results: the process presented in this paper could reduce the work load of 20% with respect to the work load needed in the fully manually selection, with a recall of 100%. Conclusions: the extraction of knowledge from scientific studies through Linked Data and text mining techniques could be used in the selection phase of the systematic review process to reduce the work load and subjectivity bia
Interacting dark energy from the joint analysis of the power spectrum and bispectrum multipoles with the EFTofLSS
Interacting dark energy models have been suggested as alternatives to the
standard cosmological model, CDM. We focus on a phenomenologically
interesting class of dark scattering models that is characterised by pure
momentum exchange between dark energy and dark matter. This model extends the
parameter space with respect to CDM by two parameters, and ,
which define the dark energy equation of state and the strength of the coupling
between dark energy and dark matter, respectively. In order to test
non-standard cosmologies with Stage-IV galaxy clustering surveys, it is crucial
to model mildly nonlinear scales and perform precision vs accuracy tests. We
use the Effective Field Theory of Large-Scale Structure, and we perform
validation tests by means of an MCMC analysis using a large set of N-body
simulations. We find that adding the bispectrum monopole to the power spectrum
multipoles improves the constraints on the dark energy parameters by for Mpc without introducing
biases in the parameter estimation. We also find that the same improvement can
be achieved with more moderate scale cuts and the use of bias relations, or
with the addition of the bispectrum quadrupole. Finally, we study degeneracies
between the dark energy parameters and the scalar amplitude and
discuss the corresponding projection effects, as well as degeneracies with
other cosmological parameters.Comment: 22 pages, 13 figures; V2: Matches version accepted for publication in
MNRAS, includes a new analysis of degeneracies with cosmological parameter
Male breast cancer.
Male breast cancer (MaleBC) is a rare disease, accounting for <1% of all male tumors. During the last few years, there has been an increase in the incidence of this disease, along with the increase in female breast cancer (FBC). Little is known about the etiology of MaleBC: hormonal, environmental and genetic factors have been reported to be involved in its pathogenesis. Major risk factors include clinical disorders carrying hormonal imbalances, radiation exposure and, in particular, a positive family history (FH) for BC, the latter suggestive of genetic susceptibility. Rare mutations in high-penetrance genes (BRCA1 and BRCA2) confer a high risk of BC development; low-penetrance gene mutations (i.e. CHEK-2) are more common but involve a lower risk increase. About 90% of all male breast tumors have proved to be invasive ductal carcinomas, expressing high levels of hormone receptors with evident therapeutic returns. The most common clinical sign of BC onset in men is a painless palpable retroareolar lump, which should be evaluated by means of mammography, ultrasonography and core biopsy or fine needle aspiration (FNA). To date, there are no published data from prospective randomized trials supporting a specific therapeutic approach in MaleBC. Tumor size together with the number of axillary nodes involved are the main prognostic factors and should guide the treatment choice. Locoregional approaches include surgery and radiotherapy (RT), depending upon the initial clinical presentation. When systemic treatment (adjuvant, neoadjuvant and metastatic) is delivered, the choice between hormonal and or chemotherapy (CT) should depend upon the clinical and biological features, according to the FBC management guidelines. However great caution is required because of high rates of age-related comorbidities
A very fast inference algorithm for finite-dimensional spin glasses: Belief Propagation on the dual lattice
Starting from a Cluster Variational Method, and inspired by the correctness
of the paramagnetic Ansatz (at high temperatures in general, and at any
temperature in the 2D Edwards-Anderson model) we propose a novel message
passing algorithm --- the Dual algorithm --- to estimate the marginal
probabilities of spin glasses on finite dimensional lattices. We show that in a
wide range of temperatures our algorithm compares very well with Monte Carlo
simulations, with the Double Loop algorithm and with exact calculation of the
ground state of 2D systems with bimodal and Gaussian interactions. Moreover it
is usually 100 times faster than other provably convergent methods, as the
Double Loop algorithm.Comment: 23 pages, 12 figures. v2: improved introductio
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