957 research outputs found

    Topological aspects in the photonic crystal analog of single-particle transport in quantum Hall systems

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    We present a perturbative approach to derive the semiclassical equations of motion for the two-dimensional electron dynamics under the simultaneous presence of static electric and magnetic fields, where the quantized Hall conductance is known to be directly related to the topological properties of translationally invariant magnetic Bloch bands. In close analogy to this approach, we develop a perturbative theory of two-dimensional photonic transport in gyrotropic photonic crystals to mimic the physics of quantum Hall systems. We show that a suitable permittivity grading of a gyrotropic photonic crystal is able to simulate the simultaneous presence of analog electric and magnetic field forces for photons, and we rigorously derive the topology-related term in the equation for the electromagnetic energy velocity that is formally equivalent to the electronic case. A possible experimental configuration is proposed to observe a bulk photonic analog to the quantum Hall physics in graded gyromagnetic photonic crystals.Comment: to be published in Phys Rev

    Groups with restriction on non-normal subgroups

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    This thesis contains a study of groups with restrictions on non-normal subgroups and of groups whose subgroups not satisfying a property X have finitely many normalizers

    On The Weak-Coupling Limit for Bosons and Fermions

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    In this paper we consider a large system of Bosons or Fermions. We start with an initial datum which is compatible with the Bose-Einstein, respectively Fermi-Dirac, statistics. We let the system of interacting particles evolve in a weak-coupling regime. We show that, in the limit, and up to the second order in the potential, the perturbative expansion expressing the value of the one-particle Wigner function at time tt, agrees with the analogous expansion for the solution to the Uehling-Uhlenbeck equation. This paper follows in spirit the companion work [\rcite{BCEP}], where the authors investigated the weak-coupling limit for particles obeying the Maxwell-Boltzmann statistics: here, they proved a (much stronger) convergence result towards the solution of the Boltzmann equation

    Macroscopic Forces driven by Resonant Neutrino Conversion

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    We show that neutrino oscillations in matter are always accompanied by collective forces on the medium. This effect may produce interesting consequences for the background and the neutrino oscillations themselves. The force is maximal in the case of resonant neutrino conversion in the adiabatic regime. We study here the forces driven by νe−νμ,τ\nu_e-\nu_{\mu,\tau} and νe−νs\nu_e-\nu_s MSW conversion and shortly discuss their possible relevance for the dynamics of a type II supernova.Comment: 9 LaTeX pages, 1 ps figure file. Format changed. One formula corrected. Some comments added to the text. Accepted for publication on Phys. Lett.

    Sexual Minority Status, Anxiety–Depression, and Academic Outcomes: The Role of Campus Climate Perceptions among Italian Higher Education Students

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    Students from sexual minorities generally describe Higher Education contexts as unwelcoming and chilly environments. Based on the Minority Stress theory, these disparities in climate perceptions may lead sexual minority students to negative health and academic outcomes. To date, research documenting the experience of sexual minority students within European Higher Education Institutions is limited. Framed within campus climate literature, the current study aimed to expand on previous knowledge by investigating the associations between sexual minority status, students’ perceptions of campus climate and psychological (i.e., anxiety–depression), and academic outcomes (i.e., intellectual and academic success and considering leaving the university) using a self-selected sample of 868 Italian university students (17.9% sexual minority students). The results showed that sexual minority status was associated with negative perceptions of campus climate, which, in turn, were associated with higher levels of anxiety–depression symptoms, lowered academic success, and a high probability of considering leaving university. Further research is needed to investigate the experience of sexual minority students within European Higher Education contexts and to explore possible actions that could contribute to fostering a greater sense of belonging to the campus community for all students, and particularly for students from sexual minority groups

    Recognition of Daily Gestures with Wearable Inertial Rings and Bracelets

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    Recognition of activities of daily living plays an important role in monitoring elderly people and helping caregivers in controlling and detecting changes in daily behaviors. Thanks to the miniaturization and low cost of Microelectromechanical systems (MEMs), in particular of Inertial Measurement Units, in recent years body-worn activity recognition has gained popularity. In this context, the proposed work aims to recognize nine different gestures involved in daily activities using hand and wrist wearable sensors. Additionally, the analysis was carried out also considering different combinations of wearable sensors, in order to find the best combination in terms of unobtrusiveness and recognition accuracy. In order to achieve the proposed goals, an extensive experimentation was performed in a realistic environment. Twenty users were asked to perform the selected gestures and then the data were off-line analyzed to extract significant features. In order to corroborate the analysis, the classification problem was treated using two different and commonly used supervised machine learning techniques, namely Decision Tree and Support Vector Machine, analyzing both personal model and Leave-One-Subject-Out cross validation. The results obtained from this analysis show that the proposed system is able to recognize the proposed gestures with an accuracy of 89.01% in the Leave-One-Subject-Out cross validation and are therefore promising for further investigation in real life scenarios

    Mediterranean diet, endothelial function and vascular inflammatory markers.

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    AbstractObjectivesTo discuss present knowledge about the relation between adipose tissue, inflammation and the Mediterranean-style diet.DesignReview of the literature and personal perspectives.Setting and resultsRecent studies indicate that adipose tissue is an endocrine organ producing numerous proteins, collectively referred to as adipokines, with broad biological activity, which play an important autocrine role in obesity-associated complications. Adipose tissue in general and visceral fat in particular are thought to be key regulators of inflammation which is heavily involved in the onset and development of atherothrombotic disease. Moreover, chronic inflammation may also represent a triggering factor in the origin of the metabolic syndrome and type 2 diabetes mellitus. An increased release of proinflammatory adipokines from the visceral adipose tissue, associated with a reduced secretion of anti-inflammatory adipokines and cytokines, could determine a low-grade chronic inflammatory state which might play a role in the future development of the metabolic syndrome, diabetes and atherosclerosis through both insulin resistance and endothelial dysfunction. Interventions aimed at decreasing weight loss and improving adherence to a Mediterranean-style diet in people with obesity or metabolic syndrome decrease the inflammatory milieu and ameliorate both insulin resistance and endothelial dysfunction.ConclusionsAppropriate dietary patterns, as those associated with the eating model of Mediterranean-type diets, represent therapeutic strategies to reduce inflammation and the associated metabolic and cardiovascular risk

    Sexual dysfunction and the Mediterranean diet.

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    AbstractObjectivesTo discuss present knowledge about the relation between sexual dysfunction, metabolic factors and the Mediterranean-style diet.DesignReview of the literature and personal perspectives.Setting and resultsSexual problems appear to be widespread in society, influenced by both health-related and psychosocial factors, and are associated with impaired quality of life. Epidemiological studies suggest that modifiable health behaviours, including physical activity and leanness, are associated with a reduced risk for erectile dysfunction (ED) among men. Data from other surveys also indicate a higher prevalence of impotence in obese men. Obesity and the metabolic syndrome may be a risk factor for ED. The high prevalence of ED in patients with cardiovascular risk factors suggests that abnormalities of the vasodilator system of penile arteries play an important role in the pathophysiology of ED. We have shown that one-third of obese men with ED can regain their sexual activity after 2 years of adopting health behaviours, including a Mediterranean-style diet associated with regular exercise.ConclusionsWestern societies actually spend a huge part of their health care costs on chronic disease treatment and interventions for risk factors. The adoption of healthy lifestyles can reduce the prevalence of obesity and the metabolic syndrome, and hopefully the burden of sexual dysfunction

    Ambient Assisted Living and Ageing: Preliminary Results of RITA Project

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    The ageing of population is a social phenomenon that most of worldwide countries are facing. They are, and will be even more in the future, indeed trying to find solutions for improving quality of life of their elderly citizens. The project RITA wants to demonstrate that an update of the current socio-medical services with an Ambient Assisted Living (AAL) approach could improve the service efficiency and the quality of life of both elderly and caregiver. This paper presents the preliminary results obtained in RITA

    L’USO DELL’ENDOMICROSCOPIA CONFOCALE NELLO STUDIO IN VIVO DELLA CARATTERISTICHE TUMORALI CON PARTICOLARE RIGUARDO ALLA NEO-ANGIOGENESI

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    AIM: Tumour neoangiogenesis is a key factor in tumour progression and metastatic spread and the possibility to assess tumour angiogenesis might provide prognostic information. The aim of this study was to establish the role of probe-based confocal laser endomicroscopy (p-CLE) in the identification of vascular architecture and specific morphological patterns in normal colorectal mucosa and malignant lesions during routine endoscopy. METHOD: Fourteen consecutive patients with colorectal cancer were included. The following features were identified and then compared between normal and neoplastic mucosa on p-CLE images: vessel shape (straight vs irregular) vessel diameter the 'branching patterns' vessel permeability (fluorescein leakage) and blood flow (normal vs defective flux). Immunohistochemistry was used to confirm the presence and to study the morphology of vascular structures (CD-34 staining) and 'neo-vessels' (WT-1 staining) on tumour and normal mucosal sections. RESULTS: Tumour vessels appeared as irregular, ectatic and with a highly variable calibre and branching patterns on p-CLE images. The mean diameter of tumour vessels was significantly larger than those in normal mucosa (weighted mean difference 3.38, 95% CI 2.65-4.11, P = 0.01). Similarly, 'vessel branching' (OR 2.74, 95% CI 1.23-6.14, P = 0.01), fluorescent dye 'extravasation' (OR 3.46, 95% CI 1.39-8.57, P = 0.01) were significantly more frequent in colorectal cancer than in normal colorectal mucosa. Immunohistochemistry corroborated the p-CLE findings, showing higher vascularity in tumour sections due to neoformed vessels, presenting irregular patterns. CONCLUSION: Probe-based confocal laser endomicroscopy provides a noninvasive characterization of the microvascular architecture of colonic mucosa. Different morphological patterns have been described, discriminating normal and malignant microvascular networks in colorectal mucosa
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