Dimerized ground states in spin-S frustrated systems

We study a family of frustrated anti-ferromagnetic spin-$S$ systems with a fully dimerized ground state. This state can be exactly obtained without the need to include any additional three-body interaction in the model. The simplest members of the family can be used as a building block to generate more complex geometries like spin tubes with a fully dimerized ground state. After present some numerical results about the phase diagram of these systems, we show that the ground state is robust against the inclusion of weak disorder in the couplings as well as several kinds of perturbations, allowing to study some other interesting models as a perturbative expansion of the exact one. A discussion on how to determine the dimerization region in terms of quantum information estimators is also presented. Finally, we explore the relation of these results with a the case of the a 4-leg spin tube which recently was proposed as the model for the description of the compound Cu$_2$Cl$_4$D$_8$C$_4$SO$_2$, delimiting the region of the parameter space where this model presents dimerization in its ground state.Comment: 10 pages, 9 figure

Phase diagram study of a dimerized spin-S zig-zag ladder

The phase diagram of a frustrated spin-$S$ zig-zag ladder is studied through different numerical and analytical methods. We show that for arbitrary $S$, there is a family of Hamiltonians for which a fully-dimerized state is an exact ground state, being the Majumdar-Ghosh point a particular member of the family. We show that the system presents a transition between a dimerized phase to a N\'eel-like phase for $S=1/2$, and spiral phases can appear for large $S$. The phase diagram is characterized by means of a generalization of the usual Mean Field Approximation (MFA). The novelty in the present implementation is to consider the strongest coupled sites as the unit cell. The gap and the excitation spectrum is analyzed through the Random Phase Approximation (RPA). Also, a perturbative treatment to obtain the critical points is discussed. Comparisons of the results with numerical methods like DMRG are also presented.Comment: 14 pages, 6 figures. Some typos were corrected, and notation was clarifie

Isospin fluctuations in spinodal decomposition

We study the isospin dynamics in fragment formation within the framework of an analytical model based on the spinodal decomposition scenario. We calculate the probability to obtain fragments with given charge and neutron number, focussing on the derivation of the width of the isotopic distributions. Within our approach this is determined by the dispersion of N/Z among the leading unstable modes, due to the competition between Coulomb and symmetry energy effects, and by isovector-like fluctuations present in the matter that undergoes the spinodal decomposition. Hence the widths exhibit a clear dependence on the properties of the Equation of State. By comparing two systems with different values of the charge asymmetry we find that the isotopic distributions reproduce an isoscaling relationship.Comment: 18 RevTex4 pages, 6 eps figure

Relativistic Approach to Superfluidity in Nuclear Matter

Pairing correlations in symmetric nuclear matter are studied within a relativistic mean-field approximation based on a field theory of nucleons coupled to neutral ($\sigma$ and $\omega$) and to charged ($\varrho$) mesons. The Hartree-Fock and the pairing fields are calculated in a self-consistent way. The energy gap is the result of a strong cancellation between the scalar and vector components of the pairing field. We find that the pair amplitude vanishes beyond a certain value of momentum of the paired nucleons. This fact determines an effective cutoff in the gap equation. The value of this cutoff gives an energy gap in agreement with the estimates of non relativistic calculations.Comment: 21 pages, REVTEX, 8 ps-figures, to appear in Phys.Rev.C. e-mail: [email protected]

Orthorexia and anorexia nervosa: Two distinct phenomena? A cross-cultural comparison of orthorexic behaviours in clinical and non-clinical samples

BACKGROUND: Orthorexia nervosa (ON) is defined as pathological healthful eating. The aim of this study was to investigate whether there is any difference in orthorexic behaviours between clinical and non-clinical groups, and in different cultural contexts. . METHODS: Recruitment involved both female patients with anorexia nervosa (AN) and healthy controls (HC) from Italy and Poland (N = 23 and N = 35 AN patients; and N = 39 and N = 39 HCs, in Italy and Poland, respectively). Assessment of orthorexic behaviours was performed with the ORTO-15 test. RESULTS: Statistically significant differences were found between Italian women in the AN and HC group, whereas no difference between Polish women in the AN and HC group was found. Both Italian groups scored significantly higher than the Polish ones on the ORTO-15. CONCLUSIONS: Differences have been found between the Italian and Polish samples, both in the percentage of individuals with orthorexic behaviours as suggested by an ORTO 15 score below the cutoff, and in the mean ORTO 15 scores in the AN and HC groups, suggesting cross-cultural differences in orthorexic behaviours, whose meaning is currently difficult to understand

Energy Independence of a Small Office Community Powered by Photovoltaic-Wind Hybrid Systems in Widely Different Climates

Hybrid renewable energy systems are an optimal solution for small energy communities’ energy supply. One of the critical issues is the strong correlation of these systems with outdoor climatic conditions. The goal is to make local communities increasingly energy independent. To this end, an in-depth analysis of the behaviour of hybrid photovoltaic (PV)–wind systems powering small office communities in 48 locations around the world characterized by widely varying climates was conducted. System sizes, assumed to be stand-alone or grid-connected, were varied, for a total of 343 system power configurations. Highest satisfied load fraction (SLF) values are obtained with a significant predominance of PV over wind; the trend is more pronounced in dry and continental climates (zones B and D according to the Köppen climate classification). The utilization factor (UF) values of 1 are rarely reached and never in the wind-only or PV-only configurations. In all climates, the grid energy interaction factor (GEIF) values of zero are never reached but come very close. The benefit-cost ratio (BCR) of grid-connected systems is significantly higher than stand-alone systems

The psychopathology of body image in orthorexia nervosa

The human body has a complex meaning and role in everybody\u2019s life and experience. Body image has two main components: body percept (the internal visual image of body shape and size) and body concept (the level of satisfaction with one\u2019s body), whose specific alterations may lead to different conditions, such as overestimation of one\u2019s own body dimensions, negative feelings and thoughts towards the body, body avoidance and body checking behavior. Moreover, body dissatisfaction can be associated with a variety of other mental health and psychosocial conditions, but only a few studies have explored the body image construct in orthorexia nervosa (ON). ON is a condition characterized by concern and fixation about healthy eating, with mixed results available in the literature about the presence of body image disorders. The aim of this manuscript is to present the main findings from the literature about the psychopathology of body image in ON. Summarizing, while theoretically the presence of body image disturbances should help clinicians to differentiate ON from eating disorders, further research is needed to confirm this finding. It is not clear whether the body image disorder in ON depends on an altered body percept or body concept, and the relationship between the disordered eating behavior and body image disorder still needs to be disentangled. Further studies regarding the relationship between ON and body image could be helpful to better understand the relevance of body image as a transdiagnostic factor and its potential value as target for treatment intervention

Quality-aware mashup composition: issues, techniques and tools

Web mashups are a new generation of applications based on the composition of ready-to-use, heterogeneous components. In different contexts, ranging from the consumer Web to Enterprise systems, the potential of this new technology is to make users evolve from passive receivers of applications to actors actively involved in the creation of their artifacts, thus accommodating the inherent variability of the users’ needs. Current advances in mashup technologies are good candidates to satisfy this requirement. However, some issues are still largely unexplored. In particular, quality issues specific for this class of applications, and the way they can guide the users in the identification of adequate components and composition patterns, are neglected. This paper discusses quality dimensions that can capture the intrinsic quality of mashup components, as well as the components’ capacity to maximize the quality and the userperceived value of the overall composition. It also proposes an assisted composition process in which quality becomes the driver for recommending to the users how to complete mashups, based on the integration of quality assessment and recommendation techniques within a tool for mashup development

Novel Bifunctional Compounds Targeting Nicotine and Dopamine Receptor Subtypes: Synthesis and Pharmacological Investigation

Future therapies for diseases associated with altered dopaminergic signaling, including Parkinson\u2019s disease, schizophrenia and drug addiction or drug dependence, may be substantially built on the existence of intramembrane receptor-receptor interactions within receptor mosaics where it is believed that the D2 receptor may operate as the \u201chub receptor\u201d [1]. In particular, it has been proposed that striatal dopaminergic neurotransmission could be under the control of receptor heteromers containing D2 autoreceptors and non-alpha7 nicotinic acetylcholine heteroreceptors [2]. In an attempt to investigate the biochemical and functional interactions between dopaminergic autoreceptors and nAChRs containing the beta2 subunit, we designed and prepared a group of potential bifunctional derivatives incorporating a D2/D3 agonist moiety and a nicotinic alpha4beta2 antagonist fragment, linked by polymethylene spacers of different length. The new compounds have been biologically characterized for their affinity/specificity/functional profile at the target nACh and D2 receptor subtypes. The synthesis of the designed derivatives and the results of their pharmacological investigation will be presented and discussed. [1] K.Fuxe, D.Marcellino, A.Rivera, Z.Diaz-Cabiale, M.Filip, B.Gago, D.C.S.Roberts, U.Langel, S.Genedani, L.Ferraro, A.de la Calle, J.Narvaez, S.Tanganelli, A.Woods, L.F.Agnati, Brain Res.Rev., 58, 2008, 415-452. [2] D.Quarta, F.Ciruela, K.Patkar, J.Borycz, M.Solinas, C.Lluis, R.Franco, R.A.Wise, S.R.Goldberg, B.T.Hope, A.Woods, S.Ferr\ue9, Neuropsychopharmacol., 32, 2007, 35-42

SMN - A chaperone for nuclear RNP social occasions?

Survival Motor Neuron (SMN) protein localizes to both the nucleus and the cytoplasm. Cytoplasmic SMN is diffusely localized in large oligomeric complexes with core member proteins, called Gemins. Biochemical and cell biological studies have demonstrated that the SMN complex is required for the cytoplasmic assembly and nuclear transport of Sm-class ribonucleoproteins (RNPs). Nuclear SMN accumulates with spliceosomal small nuclear (sn)RNPs in Cajal bodies, sub-domains involved in multiple facets of snRNP maturation. Thus, the SMN complex forms stable associations with both nuclear and cytoplasmic snRNPs, and plays a critical role in their biogenesis. In this review, we focus on potential functions of the nuclear SMN complex, with particular emphasis on its role within the Cajal body