Effective mapping of spin-1 chains onto integrable fermionic models. A study of string and Neel correlation functions

We derive the dominant contribution to the large-distance decay of correlation functions for a spin chain model that exhibits both Haldane and Neel phases in its ground state phase diagram. The analytic results are obtained by means of an approximate mapping between a spin-1 anisotropic Hamiltonian onto a fermionic model of noninteracting Bogolioubov quasiparticles related in turn to the XY spin-1/2 chain in a transverse field. This approach allows us to express the spin-1 string operators in terms of fermionic operators so that the dominant contribution to the string correlators at large distances can be computed using the technique of Toeplitz determinants. As expected, we find long-range string order both in the longitudinal and in the transverse channel in the Haldane phase, while in the Neel phase only the longitudinal order survives. In this way, the long-range string order can be explicitly related to the components of the magnetization of the XY model. Moreover, apart from the critical line, where the decay is algebraic, we find that in the gapped phases the decay is governed by an exponential tail multiplied by algebraic factors. As regards the usual two points correlation functions, we show that the longitudinal one behaves in a 'dual' fashion with respect to the transverse string correlator, namely both the asymptotic values and the decay laws exchange when the transition line is crossed. For the transverse spin-spin correlator, we find a finite characteristic length which is an unexpected feature at the critical point. We also comment briefly the entanglement features of the original system versus those of the effective model. The goodness of the approximation and the analytical predictions are checked versus density-matrix renormalization group calculations.Comment: 28 pages, plain LaTeX, 2 EPS figure

A Model of DC-DC Converter with Switched-Capacitor Structure for Electric Vehicle Applications

In this paper, a DC-DC converter with an innovative topology for automotive applications is proposed. The goal of the presented power converter is the electrical storage system management of an electric vehicle (EV). The presented converter is specifically compliant with a 400 V battery, which represents the high-voltage primary source of the system. This topology is also able to act as a bidirectional power converter, so that in this case, the output section is an active stage, which is able to provide power as, for example, in the case of a low-voltage battery or a supercapacitor. The proposed topology can behave either in step-down or in step-up mode, presenting in both cases a high gain between the input and output voltage. Simulation results concerning the proposed converter, demonstrating the early feasibility of the system, were obtained in a PowerSIM environment and are described in this paper

Neural Correlates of Direct Access Trading in a Real Stock Market: An fMRI Investigation

Background: While financial decision making has been barely explored, no study has previously investigated the neural correlates of individual decisions made by professional traders involved in real stock market negotiations, using their own financial resources. Aim: We sought to detect how different brain areas are modulated by factors like age, expertise, psychological profile (speculative risk seeking or aversion) and, eventually, size and type (Buy/Sell) of stock negotiations, made through Direct Access Trading (DAT) platforms. Subjects and methods: Twenty male traders underwent fMRI while negotiating in the Italian stock market using their own preferred trading platform. Results: At least 20 decision events were collected during each fMRI session. Risk averse traders performed a lower number of financial transactions with respect to risk seekers, with a lower average economic value, but with a higher rate of filled proposals. Activations were observed in cortical and subcortical areas traditionally involved in decision processes, including the ventrolateral and dorsolateral prefrontal cortex (vlPFC, dlPFC), the posterior parietal cortex (PPC), the nucleus accumbens (NAcc), and dorsal striatum. Regression analysis indicated an important role of age in modulating activation of left NAcc, while traders' expertise was negatively related to activation of vlPFC. High value transactions were associated with a stronger activation of the right PPC when subjects' buy rather than sell. The success of the trading activity, based on a large number of filled transactions, was related with higher activation of vlPFC and dlPFC. Independent of chronological and professional age, traders differed in their attitude to DAT, with distinct brain activity profiles being detectable during fMRI sessions. Those subjects who described themselves as very self-confident, showed a lower or absent activation of both the caudate nucleus and the dlPFC, while more reflexive traders showed greater activation of areas involved in strategic decision making. Discussion: The neural correlates in DAT are similar to those observed in other decision making contexts. Trading is handled as a well-learned automatic behavior by expert traders; for those who mostly rely on heuristics, cognitive effort decreases, and transaction speed increases, but decision efficiency lowers following a poor involvement of the dlPFC

The Effect of Simple Melodic Lines on Aesthetic Experience: Brain Response to Structural Manipulations

This fMRI study investigates the effect of melody on aesthetic experience in listeners na\uefve to formal musical knowledge. Using simple melodic lines, whose syntactic structure was manipulated, we created systematic acoustic dissonance. Two stimulus categories were created: canonical (syntactically \u201ccorrect,\u201d in the Western culture) and modified (made of an altered version of the canonical melodies). The stimuli were presented under two tasks: listening and aesthetic judgment. Data were analyzed as a function of stimulus structure (canonical and modified) and stimulus aesthetics, as appraised by each participant during scanning. The critical contrast modified versus canonical stimuli produced enhanced activation of deep temporal regions, including the parahippocampus, suggesting that melody manipulation induced feelings of unpleasantness in the listeners. This was supported by our behavioral data indicating decreased aesthetic preference for the modified melodies. Medial temporal activation could also have been evoked by stimulus structural novelty determining increased memory load for the modified stimuli. The analysis of melodies judged as beautiful revealed that aesthetic judgment of simple melodies relied on a fine-structural analysis of the stimuli subserved by a left frontal activation and, possibly, on meaning attribution at the charge of right superior temporal sulcus for increasingly pleasurable stimuli

Effects of Probiotics Supplementation on Risk and Severity of Infections in Athletes: A Systematic Review

The aim of this review was to appraise the literature on the effects of probiotics supplementation on gastrointestinal (GI) and upper respiratory tract infection (URTI) risk and prognosis in athletes. The search was conducted using the following electronic databases: MEDLINE (PubMed); Web of Science; Scopus; and SPORTDiscus (EBSCO). According to the PRISMA guidelines, randomized controlled studies performed on healthy athletes with a note dose of probiotics supplementation were considered. From the 2304 articles found, after eliminating reviews and studies on animals and unhealthy subjects and after screening of titles and abstracts, 403 studies were considered eligible. From these, in accordance with the inclusion and exclusion criteria, 16 studies were selected, ten of which concerned endurance athletes. The majority of the studies reported beneficial effects of probiotics in reducing the risk of developing the examined infections or the severity of related symptoms. However, due to the differences in formulations used and populations analyzed in the available studies, further research is needed in this field to achieve stronger and more specific evidence

Discrepancies between explicit and implicit evaluation of aesthetic perception ability in individuals with autism: A potential way to improve social functioning

Background: The capacity to evaluate beauty plays a crucial role in social behaviour and social relationships. It is known that some characteristics of beauty are important social cues that can induce stereotypes or promote different behavioural expectations. Another crucial capacity for success in social interactions is empathy, i.e. the ability to understand and share others' mental and emotional states. Individuals with Autism Spectrum Disorder (ASD) have an impairment of empathic ability. We showed in a previous study that empathy and aesthetic perception abilities closely related. Indeed, beauty can affect different aspects of empathic behaviour, and empathy can mediate the aesthetic perception in typically developing (TD) individuals. Thus, this study evaluates the ability of aesthetic perception in ASD individuals compared to TD individuals, using the Golden Beauty behavioural task adapted for eye-tracking in order to acquire both explicit and implicit evidences. In both groups, the relationship between empathic and aesthetic perception abilities was also evaluated. Methods: Ten ASD individuals (age ± SD:20.7 ± 4.64) and ten TD individuals (age ± SD:20.17 ± 0.98) participated in the study. Participants underwent empathy tasks and then the Golden Beauty task. To assess differences in the participants' performance, we carried out a repeated measures general linear model. Results: At the explicit level, our behavioural results show an impairment in aesthetic perception ability in ASD individuals. This inability could have relevance for their ability to experience pleasure during social interactions. However, at the implicit level (eye-tracking results), ASD individuals conserved a good ability to feel aesthetic pleasure during the Golden Beauty task, thus indicating a discrepancy between the explicit and implicit evaluation of the beauty task. Finally, beauty perception appears to be linked to empathy when neither of these capacities is compromised, as demonstrated in the TD group. In contrast, this link is missed in ASD individuals. Conclusion: Overall, our results clearly show that individuals with autism are not completely blind to aesthetic pleasure: in fact, they retain an implicit ability to experience beauty. These findings could pave the way for the development of new protocols to rehabilitate ASD social functioning, exploiting their conserved implicit aesthetic perception

Vitality forms processing in the insula during action observation: a multivoxel pattern analysis

Observing how an action is done by others allows the observer to understand the cognitive and emotion state of the agent. This information, carried by the kinematics of the observed action, has been defined by Daniel Stern \u201cvitality forms\u201d. The expression and the capacity to understand the vitality forms is already present in infants, a finding indicating their importance for the development of social attunement. It has been proposed that, well before developing linguistic abilities, infants are actively engaged in non-verbal exchanges with their caregivers. This ability denotes a primordial way to relate to and understand others and presumably represents a constitutive element of interpersonal relations, namely intersubjectivity. In the present neuroimaging (fMRI) study we presented participants with videos showing hand actions performed with different velocities and asked them to judge their vitality form (gentle, neutral, rude) or their velocity (slow, medium, fast). Previous studies showed that the dorso-central insula is selectively active both during vitality form observation and execution. The aim of the present study was to assess, using multi-voxel pattern analysis (MVPA), whether in the insula there are voxels discriminating vitality form from velocity. Results showed that, consistently across subjects, in the dorso-central sector of the insula there are voxels selectively tuned to vitality forms. Supporting previous findings, these results confirm that the dorso-central insula is involved in processing the vitality forms of an action, both when carryied out in the first person and when observed in other individuals. This supports the idea that the understanding of others' behavior in terms of affective content is mediated by an automatic activation system that allows the recipient to tune in and respond to another individual's emotional state without necessarily having "formal" knowledge of what is being observed. As argued by Stern, this process would allow a synchronization with the behavior of others that underlies the first relational forms developing in early childhood

Toward A Brain-Based Theory of Beauty

We wanted to learn whether activity in the same area(s) of the brain correlate with the experience of beauty derived from different sources. 21 subjects took part in a brain-scanning experiment using functional magnetic resonance imaging. Prior to the experiment, they viewed pictures of paintings and listened to musical excerpts, both of which they rated on a scale of 1-9, with 9 being the most beautiful. This allowed us to select three sets of stimuli-beautiful, indifferent and ugly-which subjects viewed and heard in the scanner, and rated at the end of each presentation. The results of a conjunction analysis of brain activity showed that, of the several areas that were active with each type of stimulus, only one cortical area, located in the medial orbito-frontal cortex (mOFC), was active during the experience of musical and visual beauty, with the activity produced by the experience of beauty derived from either source overlapping almost completely within it. The strength of activation in this part of the mOFC was proportional to the strength of the declared intensity of the experience of beauty. We conclude that, as far as activity in the brain is concerned, there is a faculty of beauty that is not dependent on the modality through which it is conveyed but which can be activated by at least two sources-musical and visual-and probably by other sources as well. This has led us to formulate a brain-based theory of beauty

Moving Toward Emotions in the Aesthetic Experience

In this essay, we comment on our original review published in 2009 inCurrent Opinion in Neurobiologywhere, as we build a general theoretical framework that encompasses major empirical work in the field of neuroesthetics since then, we also emphasize the role of the motor system and emotions in building an aesthetic experience. Here we extend our previous view with further empirical evidence, including from clinical and developmental psychology, thus supporting the idea that our perception is not a mere "visual" copy of what is before our eyes, but the result of a complex construction, whose outcome depends on the contribution of our body and its motor potential, our senses and emotions, imagination and memories.While we offer some food for thought for future research, we conclude by introducing a fairly recent line of study that explores the role of embodiment in architecture

Analysis of meiotic segregation by triple-color fish on both total and motile sperm fractions in a t(1p;18) river buffalo bull

Chromosomal aberrations are relatively frequent pathologies in both humans and animals. Among them, translocations present a specific meiotic segregation pattern able to give a higher percentage of unbalanced gametes that can induce fertility problems. In this study, the meiotic segregation patterns of 1p, 1q and 18 Bubalus bubalis chromosomes were analyzed in both total sperm fraction and motile sperm fraction of a t(1p;18) carrier and a control bulls by triple-color FISH analysis with a pool of specific BAC probes. The frequencies of each total sperm fraction products in the carrier resulting from alternate, adjacent I, adjacent II and 3:1 segregation were 39%, 20%, 1% and 38%, respectively. On the other hand, the frequencies of each motile sperm fraction products in the carrier resulting from alternate, adjacent I, adjacent II and 3:1 segregation were 93%, 5%, 0% and 2%, respectively. The frequencies of normal sperms in the carrier were 27% and 69% in total sperm fraction and motile sperm fraction, respectively. The frequencies detected in motile sperm fraction were also validated by comparison with bull's progeny. To our knowledge, this is the first report on the meiotic segregation patterns in motile sperm fractions of B. bubalis bull carrying a chromosomal translocation. These data suggest that translocation has a very limited effect on aneuploidy in the gametes, and therefore, on the reproductive abilities of the bull