Construction of the Lyapunov spectrum in a chaotic system displaying phase synchronization

We consider a three-dimensional chaotic system consisting of the suspension of Arnold's cat map coupled with a clock via a weak dissipative interaction. We show that the coupled system displays a synchronization phenomenon, in the sense that the relative phase between the suspension flow and the clock locks to a special value, thus making the motion fall onto a lower dimensional attractor. More specifically, we construct the attractive invariant manifold, of dimension smaller than three, using a convergent perturbative expansion. Moreover, we compute via convergent series the Lyapunov exponents, including notably the central one. The result generalizes a previous construction of the attractive invariant manifold in a similar but simpler model. The main novelty of the current construction relies in the computation of the Lyapunov spectrum, which consists of non-trivial analytic exponents. Some conjectures about a possible smoothening transition of the attractor as the coupling is increased are also discussed.Comment: 24 pages, 10 figure

Hermeneutic single case efficacy design: A systematic review of published research and current standards

open4siThis article systematically reviews the methodological characteristics of Hermeneutic Single Case Efficacy Design (HSCED) studies published in peer-reviewed journals. HSCED provides researchers with a flexible and viable alternative to both between-groups and within-subject experimental designs. This article includes a description of the evolution of the methodology distinctive to HSCED; a discussion of results of HSCED studies considered within a framework of contemporary standards and guidelines for systematic case study research; a presentation of recommendations for key characteristics (e.g., diagnosis, hermeneutic analysis, adjudication procedure). Overall, the aim is provide researchers and reviewers with a resource for conducting and evaluating HSCED research. The results of a systematic review of 13 studies suggests that published HSCED research meets contemporary criteria for systematic case study research. Hermeneutic analysis and adjudication emerged as areas of HSCED practice characterized by a diversity of procedures. Although consensus exists along key dimensions of HSCED, there remains a need for further evaluation of adjudication procedures and reporting standards.openBenelli, Enrico; De Carlo, Alessandro; Biffi, Diana; Mcleod, JohnBenelli, Enrico; De Carlo, Alessandro; Biffi, Diana; Mcleod, Joh

Digital tourism gaze and mega events

Tourism and photography have been always strongly interlinked. With the rise of smartphones and social network travellers’ photography exit the boundaries of friends and family and is now available to a wider audience. This is challenging the tourism gaze theory, which postulate that tourists photography is industry-driven and socially constructed. This exploratory research studied a visual social network to understand travellers digital mediated gaze during a mega event. Particularly the study shades lights on iconic places/attractions portrayed and on the ideal self represented by the event goers highlighting the presence of iconic places and staged personal pictures

Reconfigurable photoinduced metamaterials in the microwave regime

We investigate optically reconfigurable dielectric metamaterials at gigahertz frequencies. More precisely, we study the microwave response of a subwavelength grating optically imprinted into a semiconductor slab. In the homogenized regime, we analytically evaluate the ordinary and extraordinary component of the effective permittivity tensor by taking into account the photo-carrier dynamics described by the ambipolar diffusion equation. We analyze the impact of semiconductor parameters on the gigahertz metamaterial response which turns out to be highly reconfigurable by varying the photogenerated grating and which can show a marked anisotropic behavior.Comment: 6 figures, 7 page

3D bioprinted human cortical neural constructs derived from induced pluripotent stem cells

Bioprinting techniques use bioinks made of biocompatible non-living materials and cells to build 3D constructs in a controlled manner and with micrometric resolution. 3D bioprinted structures representative of several human tissues have been recently produced using cells derived by differentiation of induced pluripotent stem cells (iPSCs). Human iPSCs can be differentiated in a wide range of neurons and glia, providing an ideal tool for modeling the human nervous system. Here we report a neural construct generated by 3D bioprinting of cortical neurons and glial precursors derived from human iPSCs. We show that the extrusion-based printing process does not impair cell viability in the short and long term. Bioprinted cells can be further differentiated within the construct and properly express neuronal and astrocytic markers. Functional analysis of 3D bioprinted cells highlights an early stage of maturation and the establishment of early network activity behaviors. This work lays the basis for generating more complex and faithful 3D models of the human nervous systems by bioprinting neural cells derived from iPSCs

Child Work: Attitudes and Policies of Consumption among a Group of Italian Youngsters

Thesis statement Little research has been carried out on the beliefs and attitudes of young people living in the industrialised countries about child work. This research relates to attitudes, perceptions, evaluations of young Italians, in relation to child work, as well as to the consequent adoption of preventative consumption policies. Methodology The research was conducted through the use of an ad-hoc questionnaire, administrated to a group of 1,250 high school students, aged 14-18. The data were analyzed using SPSS 17. Principal Component Analyses (PCA) was performed and Cronbach's alfa were computed. Results Among key findings: participants show a limited knowledge of child work; negative attitudes towards child work are closely associated to mental representation of poverty and exploitation, but more positive attitude if work is pleasant and freely chosen by the child; the majority of the participants affirms the importance of adopting concrete preventive measures to counteract child work but, at the same time, past behaviour in consumption shows a discrepancy. Conclusions and Implications - A negative attitude towards child work does not seem to be linked to the willingness to adopt policies of consumption aimed at preventing and repressing child exploitation. DOI: 10.5901/mjss.2014.v5n23p239

External validity of randomized controlled trials on Alzheimer's disease: the biases of frailty and biological aging

To date, the external validity of randomized controlled trials (RCTs) on Alzheimer's disease (AD) has been assessed only considering monodimensional variables. Nevertheless, looking at isolated and single characteristics cannot guarantee a sufficient level of appreciation of the AD patients' complexity. The only way to understand whether the two worlds (i.e., research and clinics) deal with the same type of patients is to adopt multidimensional approaches more holistically reflecting the biological age of the individual. In the present study, we compared measures of frailty/biological aging [assessed by a Frailty Index (FI)] of a sample of patients with AD resulted eligible and subsequently included in phase III RCTs compared to patients referring to the same clinical service, but not considered for inclusion. The "RCT sample" and the "real world sample" were found to be statistically similar for all the considered sociodemographic and clinical variables. Nevertheless, the "real world sample" was found to be significantly frailer compared to the "RCT sample," as indicated by higher FI scores [0.28 (SD 0.1) vs. 0.17 (SD 0.1);p < 0.001, respectively]. Moreover, when assessing the relationship between FI and age, we found that the correlation was almost null in the "RCT sample" (Spearman'sr = 0.01;p = 0.98), while it was statistically significant in the "real world sample" (r = 0.49;p = 0.02). The application of too rigid designs may result in the poor representativeness of RCT samples. It may even imply the study of a condition biologically different from that observed in the "real world." The adoption of multidimensional measures capable to capture the individual's biological age may facilitate evaluating the external validity of clinical studies, implicitly improving the interpretation of the results and their translation in the clinical arena

A comparison of CMB Angular Power Spectrum Estimators at Large Scales: the TT case

In the context of cosmic microwave background (CMB) data analysis, we compare the efficiency at large scale of two angular power spectrum algorithms, implementing, respectively, the quadratic maximum likelihood (QML) estimator and the pseudo spectrum (pseudo-Cl) estimator. By exploiting 1000 realistic Monte Carlo (MC) simulations, we find that the QML approach is markedly superior in the range l=[2-100]. At the largest angular scales, e.g. l < 10, the variance of the QML is almost 1/3 (1/2) that of the pseudo-Cl, when we consider the WMAP kq85 (kq85 enlarged by 8 degrees) mask, making the pseudo spectrum estimator a very poor option. Even at multipoles l=[20-60], where pseudo-Cl methods are traditionally used to feed the CMB likelihood algorithms, we find an efficiency loss of about 20%, when we considered the WMAP kq85 mask, and of about 15% for the kq85 mask enlarged by 8 degrees. This should be taken into account when claiming accurate results based on pseudo-Cl methods. Some examples concerning typical large scale estimators are provided.Comment: 9 pages, 7 figures. Accepted for publication in MNRA