207 research outputs found

    Periodically driven interacting electrons in 1D: a many-body Floquet approach

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    We propose a method to study the time evolution of correlated electrons driven by an harmonic perturbation. Combining Floquet formalism to include the time-dependent field and Cluster Perturbation Theory to solve the many-body problem in the presence of short-range correlations, we treat the electron double dressing - by photons and by e-e interaction - on the same footing. We apply the method to an extended Hubbard chain at half occupation and we show that in the regime of small field frequency and for given values of field strength the zero-mode Floquet band is no more gapped and the system recovers a metallic state. Our results are indicative of an omnipresent mechanism for insulator-to-metal transition in 1D systems

    Methodologies for self-organising systems:a SPEM approach

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    We define ’SPEM fragments’ of five methods for developing self-organising multi-agent systems. Self-organising traffic lights controllers provide an application scenario

    Lifestyle at Time of COVID-19: How Could Quarantine Affect Cardiovascular Risk

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    COVID-19 is causing a global pandemic with a high number of deaths and infected people. To contain the diffusion of COVID-19 virus, governments have enforced restrictions on outdoor activities or even collective quarantine on the population. Quarantine carries some long-term effects on cardiovascular disease, mainly related to unhealthy lifestyle and anxiety

    Time-evolution and dynamics of Floquet edge states in irradiated graphene nanoribbons

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    We study the solution of the time-dependent Schr¨odinger equation for systems driven out of equilibrium by a time-periodic laser field, using the Floquet equation as a mathematical tool to efficiently obtain the desired time-dependent observables. We calculate the velocity and charge of occupied states in a laserirradiated zig-zag graphene nanoribbon (zGNR), focusing on the role and properties of topologically protected edge states: their robustness against defects and disorder is tested, as well as their behavior when a bias voltage is applied across a section of the ribbon. Our results reveal the importance of the time-dependent approach to correctly calculate observables of laser-driven materials according to the occupation of states, suggesting how the properties of protected edge-states can be exploited to create flying-qubit architectures

    Quarantine and Isolation during COVID-19 outbreak: A case of online diagnosis of supraventricular arrhythmia through telemedicine

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    The present case report highlights the usefulness of telemedicine during quarantine and isolation. The patient developed a supraventricular arrhythmia, and the diagnosis and management of the arrhythmia was done online

    Expression of nuclear survivin in normal skin and squamous cell carcinoma: a possible role in tumor invasion

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    Background: Survivin is detected in few adult normal cells and it is highly expressed in cancer. Nuclear survivin facilitates cell cycle entry, while the mitochondrial pool protects cells from apoptosis. Survivin is overexpressed in keratinocyte stem cells (KSC) and protects them from apoptosis. Methods: As KSC are at the origin of squamous cell carcinoma (SCC), we evaluated survivin expression in normal and cancerous skin in vivo by immunohistochemistry and western blotting. HaCaT cells overexpressing survivin and wound-healing assay are used. Anova and Student-T tests are used for statistical analysis. Results: Survivin is localized both in the cytoplasm and in the nucleus of normal adult and young keratinocytes. Nuclear survivin is detected in one every 10/11 basal keratinocytes. When present in suprabasal cells, nuclear survivin is co-expressed with K10, but not with K15 or p75-neurotrophin-receptor (p75NTR), a transit amplifying cell marker. Nuclear, but not cytoplasmic survivin expression dramatically increases in actinic keratosis and in SCC in situ, as compared to normal epidermis, and it is highest in poorly differentiated SCC. In SCC tumors, nuclear survivin-positive cells are mainly K10/p75NTR-negative and K15-positive. In poorly differentiated tumors, survivin mostly localizes in the deep infiltrating areas. When overexpressed in keratinocytes, survivin increases cell migration. Conclusion: High survivin expression and the subcellular localization of survivin correlate with keratinocyte differentiation and are associated with undifferentiated and more invasive SCC phenotype

    Isolation and Characterization of Squamous Cell Carcinoma-Derived Stem-like Cells: Role in Tumor Formation

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    In human epidermis, keratinocyte stem cells (KSC) are characterized by high levels of β1-integrin, resulting in the rapid adhesion to type IV collagen. Since epithelial tumors originate from KSC, we evaluated the features of rapidly adhering (RAD) keratinocytes derived from primary human squamous cell carcinoma of the skin (cSCC). RAD cells expressed higher levels of survivin, a KSC marker, as compared to non-rapidly adhering (NRAD) cells. Moreover, RAD cells proliferated to a greater extent and were more efficient in forming colonies than NRAD cells. RAD cells also migrated significantly better than NRAD cells. When seeded in a silicone chamber and grafted onto the back skin of NOD SCID mice, RAD cells formed tumors 2–4 fold bigger than those derived from NRAD cells. In tumors derived from RAD cells, the mitotic index was significantly higher than in those derived from NRAD cells, while Ki-67 and survivin expression were more pronounced in RAD tumors. This study suggests that SCC RAD stem cells play a critical role in the formation and development of epithelial tumors
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