1,858 research outputs found

    Clinical trials on medicinal products in Malta following EU accession

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    Following EU Accession, Malta has to adopt EU Directives as part of its own legislation. Three such directives concern the conduct of clinical trials in European countries ­ 2001/20/EC, 2003/94/EC and 2005/28/EC. These directives, and the respective guidelines explaining their implementation, have considerably changed the way clinical trials are conducted. While the participation of Malta in clinical trials is to be encouraged for various reasons, these have to be regulated according to the legislation set out by the European Union. In themselves, what these Directives strive to achieve are mainly the safety of the study subject and the protection of the investigators from serious consequences. This short article aims to give a brief overview of these changes to prospective investigators and hospital administrators.peer-reviewe

    Domains of analyticity of Lindstedt expansions of KAM tori in dissipative perturbations of Hamiltonian systems

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    Many problems in Physics are described by dynamical systems that are conformally symplectic (e.g., mechanical systems with a friction proportional to the velocity, variational problems with a small discount or thermostated systems). Conformally symplectic systems are characterized by the property that they transform a symplectic form into a multiple of itself. The limit of small dissipation, which is the object of the present study, is particularly interesting. We provide all details for maps, but we present also the modifications needed to obtain a direct proof for the case of differential equations. We consider a family of conformally symplectic maps fμ,ϵf_{\mu, \epsilon} defined on a 2d2d-dimensional symplectic manifold M\mathcal M with exact symplectic form Ω\Omega; we assume that fμ,ϵf_{\mu,\epsilon} satisfies fμ,ϵΩ=λ(ϵ)Ωf_{\mu,\epsilon}^*\Omega=\lambda(\epsilon) \Omega. We assume that the family depends on a dd-dimensional parameter μ\mu (called drift) and also on a small scalar parameter ϵ\epsilon. Furthermore, we assume that the conformal factor λ\lambda depends on ϵ\epsilon, in such a way that for ϵ=0\epsilon=0 we have λ(0)=1\lambda(0)=1 (the symplectic case). We study the domains of analyticity in ϵ\epsilon near ϵ=0\epsilon=0 of perturbative expansions (Lindstedt series) of the parameterization of the quasi--periodic orbits of frequency ω\omega (assumed to be Diophantine) and of the parameter μ\mu. Notice that this is a singular perturbation, since any friction (no matter how small) reduces the set of quasi-periodic solutions in the system. We prove that the Lindstedt series are analytic in a domain in the complex ϵ\epsilon plane, which is obtained by taking from a ball centered at zero a sequence of smaller balls with center along smooth lines going through the origin. The radii of the excluded balls decrease faster than any power of the distance of the center to the origin

    La "Oración de gracias" de Casimiro Gómez Ortega a la Real Academia de la Historia (5 de Octubre de 1770)

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    En la presente nota ofrecemos la transcripción y edición de la Oracidn de gracias que Casimiro Gómez Ortega leyó con motivo de su ingreso en la Real Academia de la Historia, el día 5 de octubre de 1770. Por su contenido podemos situar tal discurso en el contexto de la polémica acerca de la ciencia española. Dos de los científicos que intervinieron en dicha polémica durante el período ilustrado fueron José Quer (1695-1 764) y José Cavanilles (1 754-1804), los cuales presentan matices en sus escritos o en la elaboración de los mismos, que impiden una interpretación lineal.CAICYT y el CSi

    Connecting the dots for real-time LiDAR-based object detection with YOLO

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    © 2018 Australasian Robotics and Automation Association. All rights reserved. In this paper we introduce a generic method for people and vehicle detection using LiDAR data only, leveraging a pre-trained Convolutional Neural Network (CNN) from the RGB domain. Typically with machine learning algorithms, there is an inherent trade-off between the amount of training data available and the need for engineered features. The current state-of-the-art object detection and classification heavily rely on deep CNNs trained on enormous RGB image datasets. To take advantage of this inbuilt knowledge, we propose to fine-tune You only look once (YOLO) network transferring its understanding about object shapes to upsampled LiDAR images. Our method creates a dense depth/intensity map, which highlights object contours, from the 3D-point cloud of a LiDAR scan. The proposed method is hardware agnostic, hence can be used with any LiDAR data, independently on the number of channels or beams. Overall, the proposed pipeline exploits the notable similarity between upsampled LiDAR images and RGB images preventing the need to train a deep CNN from scratch. This transfer learning makes our method data efficient while avoiding the creation of heavily engineered features. Evaluation results show that our proposed LiDAR-only detection model has equivalent performance to its RGB-only counterpart

    3D Lidar-IMU Calibration Based on Upsampled Preintegrated Measurements for Motion Distortion Correction

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    © 2018 IEEE. In this paper, we present a probabilistic framework to recover the extrinsic calibration parameters of a lidar-IMU sensing system. Unlike global-shutter cameras, lidars do not take single snapshots of the environment. Instead, lidars collect a succession of 3D-points generally grouped in scans. If these points are assumed to be expressed in a common frame, this becomes an issue when the sensor moves rapidly in the environment causing motion distortion. The fundamental idea of our proposed framework is to use preintegration over interpolated inertial measurements to characterise the motion distortion in each lidar scan. Moreover, by using a set of planes as a calibration target, the proposed method makes use of lidar point-to-plane distances to jointly calibrate and localise the system using on-manifold optimisation. The calibration does not rely on a predefined target as arbitrary planes are detected and modelled in the first lidar scan. Simulated and real data are used to show the effectiveness of the proposed method

    Carrier and Light Trapping in Graded Quantum Well Laser Structures

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    We investigated the carrier and light trapping in GaInAs/AlGaAs single quantum well laser structures by means of time resolved photoluminescence and Raman spectroscopy. The influence of the shape and depth of the confinement potential and of the cavity geometry was studied by using different AlGaAs/GaAs short-period superlattices as barriers. Our results show that grading the optical cavity improves considerably both carrier and light trapping in the quantum well, and that the trapping efficiency is enhanced by increasing the graded confining potential.Comment: PDF-format, 15 pages (including 4 figures), Applied Physics Letters (June 2000

    Periodically rippled graphene: growth and spatially resolved electronic structure

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    We studied the growth of an epitaxial graphene monolayer on Ru(0001). The graphene monolayer covers uniformly the Ru substrate over lateral distances larger than several microns reproducing the structural defects of the Ru substrate. The graphene is rippled with a periodicity dictated by the difference in lattice parameter between C and Ru. The theoretical model predict inhomogeneities in the electronic structure. This is confirmed by measurements in real space by means of scanning tunnelling spectroscopy. We observe electron pockets at the higher parts of the ripples.Comment: 5 page
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