DMRG Simulation of the SU(3) AFM Heisenberg Model

We analyze the antiferromagnetic $\text{SU}(3)$ Heisenberg chain by means of the Density Matrix Renormalization Group (DMRG). The results confirm that the model is critical and the computation of its central charge and the scaling dimensions of the first excited states show that the underlying low energy conformal field theory is the $\text{SU}(3)_1$ Wess-Zumino-Novikov-Witten model.Comment: corrections and improvements adde

Two distance-regular graphs

We construct two families of distance-regular graphs, namely the subgraph of the dual polar graph of type B_3(q) induced on the vertices far from a fixed point, and the subgraph of the dual polar graph of type D_4(q) induced on the vertices far from a fixed edge. The latter is the extended bipartite double of the former

Scaling of excitations in dimerized and frustrated spin-1/2 chains

We study the finite-size behavior of the low-lying excitations of spin-1/2 Heisenberg chains with dimerization and next-to-nearest neighbors interaction, J_2. The numerical analysis, performed using density-matrix renormalization group, confirms previous exact diagonalization results, and shows that, for different values of the dimerization parameter \delta, the elementary triplet and singlet excitations present a clear scaling behavior in a wide range of \ell=L/\xi (where L is the length of the chain and \xi is the correlation length). At J_2=J_2c, where no logarithmic corrections are present, we compare the numerical results with finite-size predictions for the sine-Gordon model obtained using Luscher's theory. For small \delta we find a very good agreement for \ell > 4 or 7 depending on the excitation considered.Comment: 4 pages, 4 eps figures, RevTeX 4 class, same version as in PR

Hidden order in bosonic gases confined in one dimensional optical lattices

We analyze the effective Hamiltonian arising from a suitable power series expansion of the overlap integrals of Wannier functions for confined bosonic atoms in a 1d optical lattice. For certain constraints between the coupling constants, we construct an explicit relation between such an effective bosonic Hamiltonian and the integrable spin-$S$ anisotropic Heisenberg model. Therefore the former results to be integrable by construction. The field theory is governed by an anisotropic non linear $\sigma$-model with singlet and triplet massive excitations; such a result holds also in the generic non-integrable cases. The criticality of the bosonic system is investigated. The schematic phase diagram is drawn. Our study is shedding light on the hidden symmetry of the Haldane type for one dimensional bosons.Comment: 5 pages; 1 eps figure. Revised version, to be published in New. J. Phy

Overflow movements and white matter abnormalities in ADHD

Multiple motor abnormalities have been identified in some children with Attention Deficit/Hyperactivity Disorder (ADHD). These include persistence of overflow movements, impaired timing of motor responses and deficits in fine motor abilities. Motor overflow is defined as co-movement of body parts not specifically needed to efficiently complete a task. The presence of age-inappropriate overflow may reflect immaturity of the cortical systems involved in automatic motor inhibition. Theories on overflow movements consistently implicate impairments in white matter (WM) tracts, including the corpus callosum. WM connections might be altered selectively in brain networks and thus influence motor behaviours. We reviewed the scientific contributions on overflow movements and WM abnormalities in ADHD. They suggest that WM abnormalities in motor/premotor circuits, which are important for motor response inhibition, might be responsible for overflow movements in patients with ADHD

Malnutrition and Gut Flora dysbiosis: specific therapies for emerging comorbidities in heart failure

Chronic heart failure is a complicated multifactorial disease with wide-spread social-economic consequences. In spite of the recent development of new drugs and therapeutic strategies, CHF-related mortality and morbidity remain high. Recent evidence suggests that changes in organs such as skeletal muscle and gut flora may play an important and independent role in CHF prognosis. This paper illustrates these phenomena, proposing how to identify them and presenting current therapies which treat organs all too often underestimated but which have a fundamental role in worsening CHF

LA QUESTIONE DELLA POLITICA ESTERA NEL DIBATTITO INTERNO AL PARTITO SOCIALISTA UNIFICATO.DAL PROGETTO DI UNIFICAZIONE ALLA NUOVA SCISSIONE: 1964-1969.

The question of foreign policy within Socialist Unity Party 1966 - 1969 The research project aims to carry out an analysis of the different positions within the Socialist Unity Party, taking into consideration the years of its political activity, 1966 \u2013 1969. The research try to follow the political debate born in these years, from some of the most important international issues such as the Vietnam War, the Arab-Israeli question and the Prague Spring; the research also analyzes the relationships between the PSU and the Socialist International. The central theme of the project will, therefore, consist of a precise examination of the various interpretations developed within the party, divided in recent years in current well-defined and often contradict each other in relation to these important events in international politics. A careful reflection on these different judgments could also allow you to determine how much the lack of a precise and systematic program of international politics has helped to speed up the process of separation of the two souls of the party. The research aims, finally, to determine whether and how the socialist unification has put into question and crisis in the traditional guidelines of the socialist party's foreign policy, and to consider, therefore, the elements of continuity or rupture with respect to the ideological principles that the party had followed until then

Identification via numerical computation of transcriptional determinants of a cell phenotype decision making

Complex cellular processes, such as phenotype decision making, are exceedingly difficult to analyze experimentally, due to the multiple-layer regulation of gene expression and the intercellular variability referred to as biological noise. Moreover, the heterogeneous experimental approaches used to investigate distinct macromolecular species, and their intrinsic differential time-scale dynamics, add further intricacy to the general picture of the physiological phenomenon. In this respect, a computational representation of the cellular functions of interest can be used to extract relevant information, being able to highlight meaningful active markers within the plethora of actors forming an active molecular network. The multiscale power of such an approach can also provide meaningful descriptions for both population and single-cell level events. To validate this paradigm a Boolean and a Markov model were combined to identify, in an objective and user-independent manner, a signature of genes recapitulating epithelial to mesenchymal transition in-vitro. The predictions of the model are in agreement with experimental data and revealed how the expression of specific molecular markers is related to distinct cell behaviors. The presented method strengthens the evidence of a role for computational representation of active molecular networks to gain insight into cellular physiology and as a general approach for integrating in-silico/in-vitro study of complex cell population dynamics to identify their most relevant drivers

Computer simulations of nematic droplets with bipolar boundary conditions

We present Monte Carlo computer simulations of model nematic droplets that mimic polymer dispersed liquid crystals (PDLC's) with bipolar boundary conditions. We investigate the orientational order and the molecular organization in these systems for various anchoring strengths and for external applied fields of different magnitude both for positive and negative susceptivity anisotropy. We report a number of simulations for system sizes from 304 to 11752 particles and calculate powder deuterium NMR spectra and polarizing microscope textures for the various cases