Papers by Giovanni Feverati
Journal of High Energy Physics, May 26, 2006
Non-linear integral equations derived from Bethe Ansatz are used to evaluate finite size correcti... more Non-linear integral equations derived from Bethe Ansatz are used to evaluate finite size corrections to the highest (i.e. anti-ferromagnetic) and immediately lower anomalous dimensions of scalar operators in N = 4 SYM. In specific, multiloop corrections are computed in the SU (2) operator subspace, whereas in the general SO(6) case only one loop calculations have been finalised. In these cases, the leading finite size corrections are given by means of explicit formulae and compared with the exact numerical evaluation. In addition, the method here proposed is quite general and especially suitable for numerical evaluations.
Nuclear Physics B, Feb 1, 1999
Lecture notes in networks and systems, 2023
PLOS ONE, 2013
a<p>Number of intermolecular donor-acceptor pairs within 5 Å in the crystal structure of th... more a<p>Number of intermolecular donor-acceptor pairs within 5 Å in the crystal structure of the complex. The number of independent donor-acceptor pairs is given in parentheses.</p>b<p>Relative translational diffusion coefficient.</p>c<p>Rotational diffusion coefficient of protein 1.</p>d<p>Rotational diffusion coefficient of protein 2.</p
Physical Chemistry Chemical Physics, 2016
Nuclear Physics B, Mar 1, 2000
Perceptual Marketing Segmentation, 2023
Perceptual Marketing Segmentation based on ADSA Multi Viewpoint ( ADSA ranking and ADSA clusterin... more Perceptual Marketing Segmentation based on ADSA Multi Viewpoint ( ADSA ranking and ADSA clustering) for better results.
Nuclear Physics B
We consider the tricritical Ising model on a strip or cylinder under the integrable perturbation ... more We consider the tricritical Ising model on a strip or cylinder under the integrable perturbation by the thermal $\phi_{1,3}$ boundary field. This perturbation induces five distinct renormalization group (RG) flows between Cardy type boundary conditions labelled by the Kac labels $(r,s)$. We study these boundary RG flows in detail for all excitations. Exact Thermodynamic Bethe Ansatz (TBA) equations are derived using the lattice approach by considering the continuum scaling limit of the $A_4$ lattice model with integrable boundary conditions. Fixing the bulk weights to their critical values, the integrable boundary weights admit a thermodynamic boundary field $\xi$ which induces the flow and, in the continuum scaling limit, plays the role of the perturbing boundary field $\phi_{1,3}$. The excitations are completely classified, in terms of string content, by $(m,n)$ systems and quantum numbers but the string content changes by either two or three well-defined mechanisms along the flow...
As the Hubbard energy at half filling is believed to reproduce at strong coupling (part of) the a... more As the Hubbard energy at half filling is believed to reproduce at strong coupling (part of) the all loop expansion of the dimensions in the SU(2) sector of the planar N=4 SYM, we compute an exact non-perturbative expression for it. For this aim, we use the effective and well-known idea in 2D statistical field theory to convert the Bethe Ansatz equations into two coupled non-linear integral equations (NLIEs). We focus our attention on the highest anomalous dimension for fixed bare dimension or length, L, analysing the many advantages of this method for extracting exact behaviours varying the length and the 't Hooft coupling, λ. For instance, we will show that the large L (asymptotic) expansion is exactly reproduced by its analogue in the BDS Bethe Ansatz, though the exact expression clearly differs from the BDS one (by non-analytic terms). Performing the limits on L and λ in different orders is also under strict control. Eventually, the precision of numerical integration of the N...
PLoS ONE, 2012
Protein oligomers are formed either permanently, transiently or even by default. The protein chai... more Protein oligomers are formed either permanently, transiently or even by default. The protein chains are associated through intermolecular interactions constituting the protein interface. The protein interfaces of 40 soluble protein oligomers of stoechiometries above two are investigated using a quantitative and qualitative methodology, which analyzes the x-ray structures of the protein oligomers and considers their interfaces as interaction networks. The protein oligomers of the dataset share the same geometry of interface, made by the association of two individual b-strands (b-interfaces), but are otherwise unrelated. The results show that the b-interfaces are made of two interdigitated interaction networks. One of them involves interactions between main chain atoms (backbone network) while the other involves interactions between side chain and backbone atoms or between only side chain atoms (side chain network). Each one has its own characteristics which can be associated to a distinct role. The secondary structure of the b-interfaces is implemented through the backbone networks which are enriched with the hydrophobic amino acids favored in intramolecular b-sheets (MCWIV). The intermolecular specificity is provided by the side chain networks via positioning different types of charged residues at the extremities (arginine) and in the middle (glutamic acid and histidine) of the interface. Such charge distribution helps discriminating between sequences of intermolecular b-strands, of intramolecular b-strands and of b-strands forming bamyloid fibers. This might open new venues for drug designs and predictive tool developments. Moreover, the b-strands of the cholera toxin B subunit interface, when produced individually as synthetic peptides, are capable of inhibiting the assembly of the toxin into pentamers. Thus, their sequences contain the features necessary for a b-interface formation. Such b-strands could be considered as 'assemblons', independent associating units, by homology to the foldons (independent folding unit). Such property would be extremely valuable in term of assembly inhibitory drug development.
PLoS ONE, 2010
The cholera toxin B pentamer (CtxB 5), which belongs to the AB 5 toxin family, is used as a model... more The cholera toxin B pentamer (CtxB 5), which belongs to the AB 5 toxin family, is used as a model study for protein assembly. The effect of the pH on the reassembly of the toxin was investigated using immunochemical, electrophoretic and spectroscopic methods. Three pH-dependent steps were identified during the toxin reassembly: (i) acquisition of a fully assembly-competent fold by the CtxB monomer, (ii) association of CtxB monomer into oligomers, (iii) acquisition of the native fold by the CtxB pentamer. The results show that CtxB 5 and the related heat labile enterotoxin LTB 5 have distinct mechanisms of assembly despite sharing high sequence identity (84%) and almost identical atomic structures. The difference can be pinpointed to four histidines which are spread along the protein sequence and may act together. Thus, most of the toxin B amino acids appear negligible for the assembly, raising the possibility that assembly is driven by a small network of amino acids instead of involving all of them.
Biosystems, 2012
We investigate the mutation-selection dynamics for an evolutionary computation model based on Tur... more We investigate the mutation-selection dynamics for an evolutionary computation model based on Turing Machines that we introduced in a previous article [1]. The use of Turing Machines allows for very simple mechanisms of code growth and code activation/inactivation through point mutations. To any value of the point mutation probability corresponds a maximum amount of active code that can be maintained by selection and the Turing machines that reach it are said to be at the error threshold. Simulations with our model show that the Turing machines population evolve towards the error threshold. Mathematical descriptions of the model point out that this behaviour is due more to the mutationselection dynamics than to the intrinsic nature of the Turing machines. This indicates that this result is much more general than the model considered here and could play a role also in biological evolution.
International Journal of Modern Physics A, 2010
In this paper, we review the basic concepts regarding quantum integrability. Special emphasis is ... more In this paper, we review the basic concepts regarding quantum integrability. Special emphasis is given on the algebraic content of integrable models. The associated algebras are essentially described by the Yang–Baxter and boundary Yang–Baxter equations depending on the choice of boundary conditions. The relation between the aforementioned equations and the braid group is briefly discussed. A short review on quantum groups as well as the quantum inverse scattering method (algebraic Bethe ansatz) is also presented.
Physical Review E, 2008
The development of a large non-coding fraction in eukaryotic DNA and the phenomenon of the code-b... more The development of a large non-coding fraction in eukaryotic DNA and the phenomenon of the code-bloat in the field of evolutionary computations show a striking similarity. This seems to suggest that (in the presence of mechanisms of code growth) the evolution of a complex code can't be attained without maintaining a large inactive fraction. To test this hypothesis we performed computer simulations of an evolutionary toy model for Turing machines, studying the relations among fitness and coding/non-coding ratio while varying mutation and code growth rates. The results suggest that, in our model, having a large reservoir of non-coding states constitutes a great (long term) evolutionary advantage.
We propose a general framework that leads to one-dimensional XX and Hubbard models in full genera... more We propose a general framework that leads to one-dimensional XX and Hubbard models in full generality, based on the decomposition of an arbitrary vector space (possibly infinite dimensional) into a direct sum of two subspaces, the two corresponding orthogonal projectors allowing one to define a R-matrix of a universal XX model, and then of a Hubbard model using a Shastry type construction. The QISM approach ensures integrability of the models, the properties of the obtained R-matrices leading to local Hubbard-like Hamiltonians. In all cases, the energies, the symmetry algebras and the scattering matrices are explicitly determined. The computation of the Bethe Ansatz equations for some subsectors of the universal Hubbard theories are determined, while they are fully computed in the XX case. A perturbative calculation in the large coupling regime is also done for the universal Hubbard models.
Non-linear integral equations derived from Bethe Ansatz are used to evaluate finite size correcti... more Non-linear integral equations derived from Bethe Ansatz are used to evaluate finite size corrections to the highest (i.e. anti-ferromagnetic) and immediately lower anomalous dimensions of scalar operators in N=4 SYM. In specific, multi-loop corrections are computed in the SU(2) operator subspace, whereas in the general SO(6) case only one loop calculations have been finalised. In these cases, the leading finite size corrections are given by means of explicit formulæ and compared with the exact numerical evaluation. In addition, the method here proposed is quite general and especially suitable for numerical evaluations.
We consider sℓ(2) minimal conformal field theories on a cylinder from a lattice perspective. To e... more We consider sℓ(2) minimal conformal field theories on a cylinder from a lattice perspective. To each allowed one-dimensional configuration path of the AL Restricted Solidon-Solid (RSOS) models we associate a physical state and a monomial in a finite fermionic algebra. The orthonormal states produced by the action of these monomials on the primary states |h 〉 generate finite Virasoro modules with dimensions given by the finitized Virasoro characters χ (N) h (q). These finitized characters are the generating functions for the double row transfer matrix spectra of the critical RSOS models. We argue that a general energy-preserving bijection exists between the one-dimensional configuration paths and the eigenstates of these transfer matrices and exhibit this bijection for the critical and tricritical Ising models in the vacuum sector. Our results extend to ZL−1 parafermion models by duality. 1
We consider the tricritical Ising model on a strip or cylinder under the integrable perturbation ... more We consider the tricritical Ising model on a strip or cylinder under the integrable perturbation by the thermal ϕ 1,3 boundary field. This perturbation induces five distinct renormalization group (RG) flows between Cardy type boundary conditions labelled by the Kac labels (r, s). We study these boundary RG flows in detail for all excitations. Exact Thermodynamic Bethe Ansatz (TBA) equations are derived using the lattice approach by considering the continuum scaling limit of the A 4 lattice model with integrable boundary conditions. Fixing the bulk weights to their critical values, the integrable boundary weights admit a thermodynamic boundary field ξ which induces the flow and, in the continuum scaling limit, plays the role of the perturbing boundary field ϕ 1,3. The excitations are completely classified, in terms of string content, by (m, n) systems and quantum numbers but the string content changes by either two or three well-defined mechanisms along the flow. We identify these mechanisms and obtain the induced maps between the relevant finitized Virasoro characters. We also solve the TBA equations numerically to determine the boundary flows for the leading excitations.
arXiv: High Energy Physics - Theory, 2007
We construct the XX and Hubbard-like models based on unitary superalgebras gl(N |M) generalizing ... more We construct the XX and Hubbard-like models based on unitary superalgebras gl(N |M) generalizing Shastry's and Maassarani's approach. We introduce the R-matrix of the gl(N |M) XX-type model; the one of the Hubbard-like model is defined by "coupling" two independent XX models. In both cases, we show that the R-matrices satisfy the Yang-Baxter equation. We derive the corresponding local Hamiltonian in the transfer matrix formalism and we determine its symmetries. A perturbative calculation "`a la Klein and Seitz" is performed. Some explicit examples are worked out. We give a description of the two-particle scattering.
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Papers by Giovanni Feverati