Universidade Federal do ABC is a Brazilian institution of higher learning based in Santo André, with operations scheduled for several municipalities in the ABC region, all in the state of São Paulo. The chairman of the committee that formulated the proposal of the university, Luiz Bevilacqua, who turned out to be its second rector, claimed that it will allow its students to be creative and daring. The UFABC is the only federal university in Brazil with 100% of Ph. Wikipedia.
Vieira S.,King's College London |
Pinaya W.H.L.,Federal University of ABC |
Mechelli A.,King's College London
Neuroscience and Biobehavioral Reviews | Year: 2017
Deep learning (DL) is a family of machine learning methods that has gained considerable attention in the scientific community, breaking benchmark records in areas such as speech and visual recognition. DL differs from conventional machine learning methods by virtue of its ability to learn the optimal representation from the raw data through consecutive nonlinear transformations, achieving increasingly higher levels of abstraction and complexity. Given its ability to detect abstract and complex patterns, DL has been applied in neuroimaging studies of psychiatric and neurological disorders, which are characterised by subtle and diffuse alterations. Here we introduce the underlying concepts of DL and review studies that have used this approach to classify brain-based disorders. The results of these studies indicate that DL could be a powerful tool in the current search for biomarkers of psychiatric and neurologic disease. We conclude our review by discussing the main promises and challenges of using DL to elucidate brain-based disorders, as well as possible directions for future research. © 2017 The Authors
Bernardini A.E.,Federal University of São Carlos |
da Rocha R.,Federal University of ABC
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2016
The Shannon based conditional entropy that underlies five-dimensional Einstein–Hilbert gravity coupled to a dilaton field is investigated in the context of dynamical holographic AdS/QCD models. Considering the UV and IR dominance limits of such AdS/QCD models, the conditional entropy is shown to shed some light onto the meson classification schemes, which corroborate with the existence of light-flavor mesons of lower spins in Nature. Our analysis is supported by a correspondence between statistical mechanics and information entropy which establishes the physical grounds to the Shannon information entropy, also in the context of statistical mechanics, and provides some specificities for accurately extending the entropic discussion to continuous modes of physical systems. From entropic informational grounds, the conditional entropy allows one to identify the lower experimental/phenomenological occurrence of higher spin mesons in Nature. Moreover, it introduces a quantitative theoretical apparatus for studying the instability of high spin light-flavor mesons. © 2016 The Author(s)
Capelle K.,Federal University of ABC |
Campo Jr. V.L.,Federal University of São Carlos
Physics Reports | Year: 2013
Density-functional theory (DFT) and model Hamiltonians are conceptually distinct approaches to the many-particle problem, which can be developed and applied independently. In practice, however, there are multiple connections between the two. This review focuses on these connections. After some background and introductory material on DFT and on model Hamiltonians, we describe four distinct, but complementary, connections between the two approaches: (i) the use of DFT as input for model Hamiltonians, in order to calculate model parameters such as the Hubbard U and the Heisenberg J. (ii) The use of model Hamiltonians as input for DFT, as in the LDA+U functional. (iii) The use of model Hamiltonians as theoretical laboratories to study aspects of DFT. (iv) The use of special formulations of DFT as computational tools for studying spatially inhomogeneous model Hamiltonians. We mostly focus on this fourth combination, model DFT, and illustrate it for the Hubbard model and the Heisenberg model. Other models that have been treated with DFT, such as the PPP model, the Gaudin-Yang δ-gas model, the XXZ chain, variations of the Anderson and Kondo models and Hooke's atom are also briefly considered. Representative applications of model DFT to electrons in crystal lattices, atoms in optical lattices, entanglement measures, dynamics and transport are described. © 2013 Elsevier B.V.
Konoplya R.A.,Kyoto University |
Konoplya R.A.,University of Tübingen |
Zhidenko A.,University of Sao Paulo |
Zhidenko A.,Federal University of ABC
Reviews of Modern Physics | Year: 2011
Perturbations of black holes, initially considered in the context of possible observations of astrophysical effects, have been studied for the past 10 years in string theory, brane-world models, and quantum gravity. Through the famous gauge/gravity duality, proper oscillations of perturbed black holes, called quasinormal modes, allow for the description of the hydrodynamic regime in the dual finite temperature field theory at strong coupling, which can be used to predict the behavior of quark-gluon plasmas in the nonperturbative regime. On the other hand, the brane-world scenarios assume the existence of extra dimensions in nature, so that multidimensional black holes can be formed in a laboratory experiment. All this stimulated active research in the field of perturbations of higher-dimensional black holes and branes during recent years. In this review recent achievements on various aspects of black hole perturbations are discussed such as decoupling of variables in the perturbation equations, quasinormal modes (with special emphasis on various numerical and analytical methods of calculations), late-time tails, gravitational stability, anti-de Sitter/conformal field theory interpretation of quasinormal modes, and holographic superconductors. We also touch on state-of-the-art observational possibilities for detecting quasinormal modes of black holes. © 2011 American Physical Society.
Cordeiro R.M.,Federal University of ABC
Biochimica et Biophysica Acta - Biomembranes | Year: 2014
Reactive oxygen species (ROS) are involved in biochemical processes such as redox signaling, aging, carcinogenesis and neurodegeneration. Although biomembranes are targets for reactive oxygen species attack, little is known about the role of their specific interactions. Here, molecular dynamics simulations were employed to determine the distribution, mobility and residence times of various reactive oxygen species at the membrane-water interface. Simulations showed that molecular oxygen (O2) accumulated at the membrane interior. The applicability of this result to singlet oxygen ( 1O2) was discussed. Conversely, superoxide (O 2-) radicals and hydrogen peroxide (H2O 2) remained at the aqueous phase. Both hydroxyl (HO) and hydroperoxyl (HO2) radicals were able to penetrate deep into the lipid headgroups region. Due to membrane fluidity and disorder, these radicals had access to potential peroxidation sites along the lipid hydrocarbon chains, without having to overcome the permeation free energy barrier. Strikingly, HO2 radicals were an order of magnitude more concentrated in the headgroups region than in water, implying a large shift in the acid-base equilibrium between HO2 and O2-. In comparison with O2, both HO and HO2 radicals had lower lateral mobility at the membrane. Simulations revealed that there were intermittent interruptions in the H-bond network around the HO radicals at the headgroups region. This effect is expected to be unfavorable for the H-transfer mechanism involved in HO diffusion. The implications for lipid peroxidation and for the effectiveness of membrane antioxidants were evaluated. © 2013 Elsevier B.V.
Nishi C.C.,Federal University of ABC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
We classify explicitly all the possible generalized CP symmetries that are definable in Δ(27) flavor models. In total, only 12 transformations are possible. We also show interesting consequences of considering some of them as residual symmetries of the neutrino sector. © 2013 American Physical Society.
Kupriyanov V.G.,Federal University of ABC
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014
In this paper we discuss classical aspects of spinor field theory on the coordinate dependent noncommutative space-time. The noncommutative Dirac equation describing spinning particle in an external vector field and the corresponding action principle are proposed. The specific choice of a star product allows us to derive a conserved noncommutative probability current and to obtain the energy-momentum tensor for free noncommutative spinor field. Finally, we consider a free noncommutative Dirac fermion and show that if the Poisson structure is Lorentz-covariant, the standard energy-momentum dispersion relation remains valid. © 2014 The Authors.
Shchesnovich V.S.,Federal University of ABC
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014
The boson sampler proposed by Aaronson and Arkhipov is a nonuniversal quantum computer, which can serve as evidence against the extended Church-Turing thesis. It samples the probability distribution at the output of a linear unitary optical network with indistinguishable single photons at the input. Four experimental groups have already tested their small-scale prototypes with up to four photons. A boson sampler with a few dozens of single photons is believed to be hard to simulate on a classical computer. For scalability of a realistic boson sampler with current technology it is necessary to know the effect of the photon mode mismatch on its operation. Here a nondeterministic model of the boson sampler is analyzed, which employs partially indistinguishable single photons emitted by identical sources. A sufficient condition on the average mutual fidelity 〈F〉 of the single photons is found, which guarantees that the realistic boson sampler outperforms the classical computer. Moreover, the boson-sampler computer with partially indistinguishable single photons is scalable and has more power than classical computers when the single-photon mode mismatch 1-〈F〉 scales as O(N-3/2) with the total number of photons N. © 2014 American Physical Society.
Shchesnovich V.S.,Federal University of ABC
Physical Review Letters | Year: 2016
It is found that identical bosons (fermions) show a generalized bunching (antibunching) property in linear networks: the absolute maximum (minimum) of the probability that all N input particles are detected in a subset of K output modes of any nontrivial linear M-mode network is attained only by completely indistinguishable bosons (fermions). For fermions K is arbitrary; for bosons it is either (i) arbitrary for only classically correlated bosons or (ii) satisfies K≥N (or K=1) for arbitrary input states of N particles. The generalized bunching allows us to certify in a polynomial in N number of runs that a physical device realizing boson sampling with an arbitrary network operates in the regime of full quantum coherence compatible only with completely indistinguishable bosons. The protocol needs only polynomial classical computations for the standard boson sampling, whereas an analytic formula is available for the scattershot version. © 2016 American Physical Society.
Shchesnovich V.S.,Federal University of ABC
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015
We generalize an approach for description of multiphoton experiments with multiport unitary linear optical devices, started in Phys. Rev. A 89, 022333 (2014)PLRAAN1050-294710.1103/PhysRevA.89.022333 with single photons in mixed spectral states, to arbitrary (multiphoton) input and arbitrary photon detectors. We show that output probabilities are always given in terms of the matrix permanents of the Hadamard product of a matrix built from the network matrix and matrices built from the spectral state of photons and spectral sensitivities of detectors. Moreover, in the case of input with up to one photon per mode, the output probabilities are given by a sum (or integral) with each term being the absolute value squared of such a matrix permanent. We conjecture that, for an arbitrary multiphoton input, zero output probability of an output configuration is always the result of an exact cancellation of quantum transition amplitudes of completely indistinguishable photons (a subset of all input photons) and, moreover, is independent of coherence between only partially indistinguishable photons. The conjecture is supported by examples. Furthermore, we propose a measure of partial indistinguishability of photons which generalizes Mandel's observation, and find the law of degradation of quantum coherence in a realistic boson-sampling device with increase of the total number of photons and/or their "classicality parameter." © 2015 American Physical Society.