SEM characterization of mm-long nanowires

The fabrication of optical fibre nanowires has recently attracted much attention [1-5]. Nanowires longer than 110mm [2] and with diameters smaller than 20 nm [5] have now been fabricated using a top-down approach. Because of the extraordinarily large ratio between length and diameter (>100000), the characterization of optical fibre nanowires requires instrumentation capable of measuring lengths over a range spanning more than five orders of magnitude. In our experiments dimensional characterization along the nanowire has been performed using an SEM and calibrated references. The samples are first attached to conductive carbon pads to avoid electrostatic build-up. Charging makes accurate metrology difficult because the electron beam can be deflected by the induced electric field on the sample. Fig. 1 illustrates a nanowire with a radius r=30nm wrapped around a microfibre with r=2µm. Variations in radius of another nanowire along its length are shown in fig. 2

New examples of Calabi-Yau threefolds and genus zero surfaces

We classify the subgroups of the automorphism group of the product of 4 projective lines admitting an invariant anticanonical smooth divisor on which the action is free. As a first application, we describe new examples of Calabi-Yau 3-folds with small Hodge numbers. In particular, the Picard number is 1 and the number of moduli is 5. Furthermore, the fundamental group is non-trivial. We also construct a new family of minimal surfaces of general type with geometric genus zero, K^2=3 and fundamental group of order 16. We show that this family dominates an irreducible component of dimension 4 of the moduli space of the surfaces of general type.Comment: 18 pages; v2: simplified some arguments in the last section, final version to appear on Communications in Contemporary Mathematic

Retinal biomarkers of Alzheimer’s disease: insights from transgenic mouse models

In this paper, we use the retina as a window into the central nervous system and in particular to assess changes in the retinal tissue associated with the Alzheimer’s disease. We imaged the retina of wild-type (WT) and transgenic mouse model (TMM) of Alzheimer’s disease with optical coherence tomography and classify retinas into the WT and TMM groups using support vector machines with the radial basis function kernel. Predictions reached an accuracy over 80% at the age of 4 months and over 90% at the age of 8 months. Texture analysis of computed fundus reference images suggests a more heterogeneous organization of the retina in transgenic mice at the age of 8 months in comparison to controls.This study was supported by the Neuroscience Mantero Belard Prize 2015 (Santa Casa da Misericórdia)(MB-1049-2015), by The Portuguese Foundation for Science and Technology (PEst-UID/NEU/04539/2013), by FEDER-COMPETE (POCI-01-0145-FEDER-007440) and Centro 2020 Regional Operational Programme (CENTRO-01-0145-FEDER-000008: BrainHealth 2020).info:eu-repo/semantics/publishedVersio

Plasma Waves in Anisotropic Superconducting Films Below and Above the Plasma Frequency

We consider wave propagation inside an anisotropic superconducting film sandwiched between two semi-infinite non-conducting bounding dieletric media such that along the c-axis, perpendicular to the surfaces, there is a plasma frequency $\omega_p$ below the superconducting gap. Propagation is assumed to be parallel to the surfaces in the dielectric medium, where amplitudes decay exponentially.Below $\omega_p$, the amplitude also evanesces inside the film, and we retrieve the experimentally measured lower dispersion relation branch, $\omega \propto \sqrt{\beta}$, and the recently proposed higher frequency branch, $\omega \propto 1/\sqrt{\beta}$.Above $\omega_p$, propagation is of the guided wave type, i.e., a dispersive plane wave confined inside the film that reflects into the dielectric interfaces,and the modes are approximately described by $\omega \approx \omega_p \sqrt{ 1+ (\beta/\beta_0)^2}$, where $\beta_0$ is discussed here.Comment: 26 pages,4 figures.Submitte

Simulations of viscous shape relaxation in shuffled foam clusters

We simulate the shape relaxation of foam clusters and compare them with the time exponential expected for Newtonian fluid. Using two-dimensional Potts Model simulations, we artificially create holes in a foam cluster and shuffle it by applying shear strain cycles. We reproduce the experimentally observed time exponential relaxation of cavity shapes in the foam as a function of the number of strain steps. The cavity rounding up results from local rearrangement of bubbles, due to the conjunction of both a large applied strain and local bubble wall fluctuations

Clinical characteristics, systemic complications, and in-hospital outcomes for patients with COVID-19 in Latin America. LIVEN-Covid-19 study : a prospective, multicenter, multinational, cohort study

Purpose: The COVID-19 pandemic has spread worldwide, and almost 396 million people have been infected around the globe. Latin American countries have been deeply affected, and there is a lack of data in this regard. This study aims to identify the clinical characteristics, in-hospital outcomes, and factors associated with ICU admission due to COVID-19. Furthermore, to describe the functional status of patients at hospital discharge after the acute episode of COVID-19. Material and methods: This was a prospective, multicenter, multinational observational cohort study of subjects admitted to 22 hospitals within Latin America. Data were collected prospectively. Descriptive statistics were used to characterize patients, and multivariate regression was carried out to identify factors associated with severe COVID-19. Results: A total of 3008 patients were included in the study. A total of 64.3% of patients had severe COVID-19 and were admitted to the ICU. Patients admitted to the ICU had a higher mean (SD) 4C score (10 [3] vs. 7 [3)], p<0.001). The risk factors independently associated with progression to ICU admission were age, shortness of breath, and obesity. In-hospital mortality was 24.1%, whereas the ICU mortality rate was 35.1%. Most patients had equal self-care ability at discharge 43.8%; however, ICU patients had worse self-care ability at hospital discharge (25.7% [497/1934] vs. 3.7% [40/1074], p<0.001). Conclusions: This study confirms that patients with SARS CoV-2 in the Latin American population had a lower mortality rate than previously reported. Systemic complications are frequent in patients admitted to the ICU due to COVID-19, as previously described in high-income countries