4,013 research outputs found

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

    Get PDF
    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

    Dialectical polyptych: an interactive movie

    Get PDF
    Most of the known video games developed by big software companies usually establish an approach to the cinematic language in an attempt to create a perfect combination of narrative, visual technique and interaction. Unlike most video games, interactive film narratives normally involve an interruption in time whenever the spectator has to make choices. “Dialectical Polyptych” is an interactive movie included in a project called “Characters looking for a spect-actor”, which aims to give the spectator on-the-fly control over film editing, thus exploiting the role of the spectator as an active subject in the presented narrative. This paper presents a system based on a 3D sensor for tracking the spectator's movements and positions, which allows seamless real-timeinteractivity with the movie. Different positions of the body prompt a change in the angle or shot within each narrative, and hand swipes allow the spectator to alternate between the two parallel narratives, both producing a complementary narrative.info:eu-repo/semantics/publishedVersio

    Mass-degenerate Higgs bosons at 125 GeV in the Two-Higgs-Doublet Model

    Get PDF
    The analysis of the Higgs boson data by the ATLAS and CMS Collaborations appears to exhibit an excess of h --> gamma\gamma events above the Standard Model (SM) expectations; whereas no significant excess is observed in h --> ZZ* --> {four lepton} events, albeit with large statistical uncertainty due to the small data sample. These results (assuming they persist with further data) could be explained by a pair of nearly mass-degenerate scalars, one of which is a SM-like Higgs boson and the other is a scalar with suppressed couplings to W+W- and ZZ. In the two Higgs doublet model, the observed \gamma\gamma and ZZ* --> {four lepton} data can be reproduced by an approximately degenerate CP-even (h) and CP-odd (A) Higgs boson for values of \sin(\beta-\alpha) near unity and 0.7 < \tan\beta < 1. An enhanced \gamma\gamma signal can also arise in cases where m_h ~ m_H, m_H ~ m_A, or m_h ~ m_H ~ m_A. Since the ZZ* --> {four lepton} signal derives primarily from a SM-like Higgs boson whereas the \gamma\gamma signal receives contributions from two (or more) nearly mass-degenerate states, one would expect a slightly different invariant mass peak in the ZZ* --> {four lepton} and \gamma\gamma channels. The phenomenological consequences of such models can be tested with additional Higgs data that will be collected at the LHC in the near future.Comment: 18 pages, 19 pdf figures, v2: references added, v3&v4: added refs and explanation

    All-optical valley switch and clock of electronic dephasing

    Full text link
    2D materials with broken inversion symmetry posses an extra degree of freedom, the valley pseudospin, that labels in which of the two energy-degenerate crystal momenta, KK or KK', the conducting carriers are located. It has been shown that shining circularly-polarized light allows to achieve close to 100% of valley polarization, opening the way to valley-based transistors. Yet, switching of the valley polarization is still a key challenge for the practical implementation of such devices due to the short coherence lifetimes. Recent progress in ultrashort laser technology now allows to produce trains of attosecond pulses with controlled phase and polarization between the pulses. Taking advantage of such technology, we introduce a coherent control protocol to turn on, off and switch the valley polarization at faster timescales than electronic and valley decoherence, that is, an ultrafast optical valley switch. We theoretically demonstrate the protocol for hBN and MoS2_2 monolayers calculated from first principles. Additionally, using two time-delayed linearly-polarized pulses with perpendicular polarization, we show that we can extract the electronic dephasing time T2T_2 from the valley Hall conductivity.Comment: 19 pages; 4 figure

    Reconstruction of attosecond beating by interference of two-photon transitions in bulk solids

    Full text link
    The reconstruction of attosecond beating by interference of two-photon transitions (RABBIT) is one of the most widely used techniques for resolving ultrafast electronic dynamics in atomic and molecular systems. As it relies on the interference of photo-electrons in vacuum, similar interference has never been contemplated in the bulk of crystals. Here we show that the interference of two-photon transitions can be recorded directly in the bulk of solids and read out with standard angle-resolved photo-emission spectroscopy. The phase of the RABBIT beating in the photoelectron spectra coming from the bulk of solids is sensitive to the relative phase of the Berry connection between bands and it experiences a shift of π\pi as one of the quantum paths crosses a band. For resonant interband transitions, the amplitude of the RABBIT oscillation decays as the pump and probe pulses are separated in time due to electronic decoherence, providing a simple interferometric method to extract dephasing times

    Assessment of lot shape in business park design

    Get PDF
    Planning and developing a business park is a complex task, whichdemands integration across various fields of design and knowledge. The first choice to be made in the design process is relate to the zoning process and the definition of the lot layout and landscape. These first decisions will constrain all subsequent decisions concerning utilities, facilities and amenities. For this reason, the assessment of those issues is crucial for the perception of the overall quality of the business park design. The main goal of this work is to present a simple indicator which can assess the lot shape in order to optimize the building form and costs, the use of its open areas, the layout and the economic spacing of roads and the service routes. The indicator lot shape evaluatesthe performance of the lot design solutions according to the concept of compactness

    Urban air dispersion model of a mid-sized city. Validation methodology

    Get PDF
    Viana do Castelo is a mid-sized city located on the northwest Portuguese seaside, which undertook the challenge of developing an environmental program leading to the integration in the Healthy Cities European Network. Within this program includes prediction of pollutant concentration for NO2, CO, PM10, O3 and C6H6. This paper presents the methodology developed to validate the modelled results. Predicted concentrations were compared against measured concentrations of a chosen pollutant: Carbon Monoxide, CO. The methodology adopted was based in BOOT statistical approach. Five comparison statistics were calculated for three test points in order to find out the quality of the modelled results. Additionally, a hourly profile of predicted versus measured concentrations was developed.(undefined

    Os inventários de recursos hídricos subterrâneos como ferramenta de suporte à gestão dos recursos hídricos à escala local

    Get PDF
    Nos últimos anos a União Europeia produziu diversa legislação relativa aos recursos hídricos subterrâneos, tendo por base a sua preservação, conservação e gestão eficiente. Portugal transpôs e implementou estas orientações, incorporando assim a questão da proteção das águas subterrâneas no planeamento, nomeadamente à escala municipal.Este trabalho pretende evidenciar a utilidade dos inventários de emergências, bem como a sua relação com a análise de vulnerabilidade preconizada na Lei Portuguesa, constituindo assim, metodologias importantes de suporte à gestão destes importantes recursos, tanto a nível municipal como local.Deste modo, apresentam-se os resultados de um inventário de recursos hídricos subterrâneos realizado na pequena bacia hidrográfica da Ribeira de Sá, localizada no concelho de Castelo de Paiva, em Portugal.Os resultados obtidos nesta área reforçam claramente a importância do conhecimento inicial dos recursos existentes, nomeadamente através da inventariação, para que se definam medidas proteção e gestão adequada

    Validation study of urban air dispersion model of Viana do Castelo

    Get PDF
    The City of Viana do Castelo in Portugal has developed an air quality program, which includes prediction of pollutant concentration for NO2, CO, PM10, O3 and C6H6. A range of numerical models were used to produce the concentration maps: the ADMS-Urban model for the pollutants dispersion; the Hills model to calculate air flow and turbulence over complex terrain, including the effects of variable surface roughness; the CORINAIR v.5 to estimate traffic emissions. This paper presents the methodology developed to validate the modelled results. Predicted concentrations were compared against measured concentrations of a chosen pollutant: Carbon Monoxide, CO. Five comparison statistics were calculated for three test points in order to find out the quality of the modelled results. Additionally, a hourly profile of predicted versus measured concentrations was developed
    corecore