3,429 research outputs found
Enhancing single-parameter quantum charge pumping in carbon-based devices
We present a theoretical study of quantum charge pumping with a single ac
gate applied to graphene nanoribbons and carbon nanotubes operating with low
resistance contacts. By combining Floquet theory with Green's function
formalism, we show that the pumped current can be tuned and enhanced by up to
two orders of magnitude by an appropriate choice of device length, gate voltage
intensity and driving frequency and amplitude. These results offer a promising
alternative for enhancing the pumped currents in these carbon-based devices.Comment: 3.5 pages, 2 figure
Floquet bound states around defects and adatoms in graphene
Recent studies have focused on laser-induced gaps in graphene which have been
shown to have a topological origin, thereby hosting robust states at the sample
edges. While the focus has remained mainly on these topological chiral edge
states, the Floquet bound states around defects lack a detailed study. In this
paper we present such a study covering large defects of different shape and
also vacancy-like defects and adatoms at the dynamical gap at
( being the photon energy). Our results, based on analytical
calculations as well as numerics for full tight-binding models, show that the
bound states are chiral and appear in a number which grows with the defect
size. Furthermore, while the bound states exist regardless the type of the
defect's edge termination (zigzag, armchair, mixed), the spectrum is strongly
dependent on it. In the case of top adatoms, the bound states quasi-energies
depend on the adatoms energy. The appearance of such bound states might open
the door to the presence of topological effects on the bulk transport
properties of dirty graphene.Comment: 16 pages, 14 figure
Floquet interface states in illuminated three-dimensional topological insulators
Recent experiments showed that the surface of a three dimensional topological
insulator develops gaps in the Floquet-Bloch band spectrum when illuminated
with a circularly polarized laser. These Floquet-Bloch bands are characterized
by non-trivial Chern numbers which only depend on the helicity of the
polarization of the radiation field. Here we propose a setup consisting of a
pair of counter-rotating lasers, and show that one-dimensional chiral states
emerge at the interface between the two lasers. These interface states turn out
to be spin-polarized and may trigger interesting applications in the field of
optoelectronics and spintronics.Comment: 5 pages with 3 figures + supplemental materia
Imaging of biliary involvement in sarcoidosis: Computed tomography, magnetic resonance cholangiopancreatography, and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging findings
Sarcoidosis is a multisystem disease usually affecting the chest, hilar lymph nodes, and lungs, but can potentially involve any organ; therefore, its clinical presentation may vary. Hepato-biliary involvement is rare, and typically asymptomatic; however, it can lead to cirrhosis, and may require liver transplantation. In this report, we present a rare case of a patient affected by sarcoidosis with hepatobiliary involvement. He presented to our hospital complaining of dyspnea triggered by moderate efforts and oppressive thoracic discomfort. Chest X-ray showed multiple bilateral nodular opacities and enlargement of both hilar regions, confirmed by a subsequent total-body computed tomography scan and positron emission tomography, which also revealed cardiac, splenic, and hepatic involvement. Liver function was studied via gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging, and magnetic resonance cholangiopancreatography (MRCP) was also performed. The diagnosis of sarcoidosis was finally achieved via liver biopsy, revealing non-necrotizing granulomas in the periportal space. The patient was treated with prednisone per os, with regression of all lesions at all levels. Although other cases of biliary sarcoidosis have been described, this report provides a complete image set of Gd-EOB-DTPA-enhanced magnetic resonance and MRCP images that is lacking in the English literature, and which may be useful for diagnosis
Co-targeting of Bcl-2 and mTOR pathway triggers synergistic apoptosis in BH3 mimetics resistant acute lymphoblastic leukemia
Several chemo-resistance mechanisms including the Bcl-2 protein family overexpression and constitutive activation of the PI3K/Akt/mTOR signaling have been documented in acute lymphoblastic leukemia (ALL), encouraging targeted approaches to circumvent this clinical problem. Here we analyzed the activity of the BH3 mimetic ABT-737 in ALL, exploring the synergistic effects with the mTOR inhibitor CCI-779 on ABT-737 resistant cells. We showed that a low Mcl-1/Bcl-2 plus Bcl-xL protein ratio determined ABT-737 responsiveness. ABT-737 exposure further decreased Mcl-1, inducing apoptosis on sensitive models and primary samples, while not affecting resistant cells. Co-inhibition of Bcl-2 and the mTOR pathway resulted cytotoxic on ABT-737 resistant models, by downregulating mTORC1 activity and Mcl-1 in a proteasome-independent manner. Although Mcl-1 seemed to be critical, ectopic modulation did not correlate with apoptosis changes. Importantly, dual targeting proved effective on ABT-737 resistant samples, showing additive/synergistic effects. Together, our results show the efficacy of BH3 mimetics as single agent in the majority of the ALL samples and demonstrate that resistance to ABT-737 mostly correlated with Mcl-1 overexpression. Co-targeting of the Bcl-2 protein family and mTOR pathway enhanced drug-induced cytotoxicity by suppressing Mcl-1, providing a novel therapeutic approach to overcome BH3 mimetics resistance in ALL
Multiterminal conductance of a floquet topological insulator
We report on simulations of the dc conductance and quantum Hall response of a Floquet topological insulator using Floquet scattering theory. Our results reveal that laser-induced edge states lead to quantum Hall plateaus once imperfect matching with the nonilluminated leads is lessened. The magnitude of the Hall plateaus, however, is not directly related to the number and chirality of all the edge states at a given energy, as usual. Instead, the plateaus are dominated by those edge states adding to the time-averaged density of states. Therefore, the dc quantum Hall conductance of a Floquet topological insulator is not directly linked to topological invariants of the full Floquet bands.publishedVersionFil: Foa Torres, Luis Eduardo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Foa Torres, Luis Eduardo Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Pérez Piskunow, Pablo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Pérez Piskunow, Pablo Matías. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Balseiro, Carlos A. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina.Fil: Balseiro, Carlos A. Comisión Nacional de Energía Atómica. Instituto Balseiro; Argentina.Fil: Balseiro, Carlos A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Usaj, Gonzalo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina.Fil: Usaj, Gonzalo. Comisión Nacional de Energía Atómica. Instituto Balseiro; Argentina.Fil: Usaj, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Física de los Materiales Condensado
Subacute pericardial abscess after aortic valve replacement: a case report
BACKGROUND: Purulent pericarditis is an infectious disease, frequently caused by gram-positive bacteria, that is rarely observed in healthy individuals, and is often associated with predisposing conditions. CASE PRESENTATION: Here, we present the case of an Escherichia coli post-surgical localized purulent pericarditis complicated by transient constrictive pericarditis and its diagnostic and therapeutic management. CONCLUSIONS: Our case report focuses on the importance of imaging-guided treatment of purulent pericardial diseases, in particular on the emerging role of 18\u2009F-labelled 2-fluoro-2-deoxy-D-glucose Positron Emission Tomography/Computed Tomography in pericardial diseases and on the management of transient constrictive pericarditis, often seen after thoracic surgery
Modeling graphene-based nanoelectromechanical devices
We report on a theoretical study of charge transport properties of graphene nanoribbons under external mechanical stress. The influence of mechanical forces on the ribbon conductance is shown to be strongly dependent on the ribbon edge symmetry, i.e., zigzag versus armchair. In contrast to zigzag-edge nanoribbons which remain robust against high strain deformations, a stretching-induced metal-semiconductor transition is obtained for armchair-edge configurations. Our results point out that armchair edge ribbons are consequently much better suited for electromechanical applications.Fil: Poetschke, M.. Technische Universität Dresden; AlemaniaFil: Rocha, C. G.. Technische Universität Dresden; AlemaniaFil: Foa Torres, Luis Eduardo Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Roche, Serge. Technische Universität Dresden; Alemania. Universite Grenoble Alpes. Institut Nanosciences et Cryogenie - Commissariat a L´Energie Atomique et Aux Energies Alternatives. Institut Nanosciences et Cryogenie; Francia. Centro de Investigación en Nanociencia y Nanotecnología (CIN2); EspañaFil: Cuniberti, G.. Technische Universität Dresden; Alemani
The feasibility of prolonged exposure therapy for PTSD in low-and middle-income countries: a review
There is a need in the global south to evaluate and implement empirically supported psychological interventions to ameliorate symptoms of posttraumatic stress disorder (PTSD). Empirically supported treatments (ESTs) have increasingly been developed and implemented, yet the majority people in the global south do not have access to these treatments for mental disorders such as PTSD. Prolonged exposure therapy has accrued substantial empirical evidence to show it as an effective treatment for PTSD. Research on the effectiveness and acceptability of prolonged exposure in a low- and middle-income countries (LMICs) are sparse. This brief report presents a review of prolonged exposure (PE) therapy and its feasibility as a trauma therapy for PTSD in LMICs. First, we present a brief overview of PE as a first-line treatment for PTSD. Second, using South Africa as a case example, we present a brief overview of traumatic stress in South Africa and how mental healthcare has developed since the abolishment of apartheid in 1994. Lastly, we discuss the challenges pertaining to the dissemination and implementation of PE in LMICs and propose future perspectives regarding the implementation of ESTs such as PE in LMICs
Tendências, boas-práticas e inovação para o ensino do empreendedorismo no jornalismo e nas indústrias criativas
O presente artigo apresenta os resultados preliminares de uma análise acerca dos modelos de ensino de empreendedorismo e inovação no campo das indústrias criativas e do jornalismo atualmente em vigor ao nível global, acrescentando como caso de estudo empírico as primeiras aplicações práticas do projeto Crebiz.eu, a nível do projeto-piloto de ensino implementado em Portugal, a sua avaliação e as reflexões conclusivas sobre as práticas implementadas e a aprendizagem realizadas na ótica da continuação do projeto. O enquadramento teórico é alicerçado pela análise de 60 exemplos de modelos de ensino do empreendedorismo aplicado a diferentes áreas científicas, retirados do panorama internacional e selecionados como boas-praticas para a contextualização do cenário atual e identificação de tendências, tendo sido identificados como base contributiva para o desenvolvimento do Business Development Laboratory Study Module.info:eu-repo/semantics/publishedVersio
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