3,477 research outputs found
An Assessment on the Use of Stationary Vehicles as a Support to Cooperative Positioning
In this paper, we consider the use of stationary vehicles as tools to enhance
the localisation capabilities of moving vehicles in a VANET. We examine the
idea in terms of its potential benefits, technical requirements, algorithmic
design and experimental evaluation. Simulation results are given to illustrate
the efficacy of the technique.Comment: This version of the paper is an updated version of the initial
submission, where some initial comments of reviewers have been taken into
accoun
A Distributed and Privacy-Aware Speed Advisory System for Optimising Conventional and Electric Vehicles Networks
One of the key ideas to make Intelligent Transportation Systems (ITS) work
effectively is to deploy advanced communication and cooperative control
technologies among the vehicles and road infrastructures. In this spirit, we
propose a consensus-based distributed speed advisory system that optimally
determines a recommended common speed for a given area in order that the group
emissions, or group battery consumptions, are minimised. Our algorithms achieve
this in a privacy-aware manner; namely, individual vehicles do not reveal
in-vehicle information to other vehicles or to infrastructure. A mobility
simulator is used to illustrate the efficacy of the algorithm, and
hardware-in-the-loop tests involving a real vehicle are given to illustrate
user acceptability and ease of the deployment.Comment: This is a journal paper based on the conference paper "Highway speed
limits, optimised consensus, and intelligent speed advisory systems"
presented at the 3rd International Conference on Connected Vehicles and Expo
(ICCVE 2014) in November 2014. This is the revised version of the paper
recently submitted to the IEEE Transactions on Intelligent Transportation
Systems for publicatio
Nuevos modelos genéticos murinos para el estudio del endotelio vascular sanguÃneo: análisis de la relevancia de c-Met durante la neovascularización en el ratón
Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de BiologÃa Molecular. Fecha de lectura: 23-07-201
Novel transition metal-catalysed reactions of allenes and bisallenes
The research in this thesis is focused on new intermolecular additions of diverse nucleophiles to allenic and bisallenic motifs catalysed by transition metals. In the first project we developed a new Au-catalysed azidation of allenes for the synthesis of functionalised allylic azides, which are important precursors to many functional groups. A cationic Au(I)-catalyst was found as a suitable activator for the allenic π-system favouring the attack of challenging azides as nucleophiles and giving access to the desired allylic azides. Deuterium-labelling experiments revealed that the reaction goes via a vinyl gold intermediate, which allowed an orthogonal functionalisation of the allenes, using as electrophile iodine to break the Au-C giving valuable iodo-alkenyl azides. Besides, preliminary mechanistic studies by NMR disclosed a possible inner-sphere mechanism with the formation of Au-N3 complexes with a continuous exchange of counterions involved in the reaction.
The second part of the present thesis was aimed to develop a novel platinum-catalysed carbo- and heterocyclization of 1,5-bisallenes to obtain 6- or 7-membered rings with and extra oxygen functional group incorporated in the skeleton of the molecule. These cyclic compounds are interesting building blocks encountered into the core of several natural products, especially in terpene and sesquiterpene family. Cationic Pt(II)-catalysts with electron-withdrawing ligands were found appropriate to lead the ring closing of these 1,5-bisallenes. The reaction seems to be triggered by the attack of oxygen nucleophiles to the activated terminal π-system of the bisallene showing different coordination modes, which give access to isomeric 6- or 7-membered rings. Deuterium labelling and preliminary mechanistic experiments revealed, that the formation of the products goes via a vinyl platinum intermediate in the different cyclization modes. Besides, the reaction has been monitored by 1H NMR in order to study the decomposition level of the bisallenes under catalytic conditions and the possible interconversion between the isomeric cyclic products
Nucleophile dependent formation of 6- and 7-membered N-heterocycles by platinum-catalysed cyclisation of 1,5-bisallenes
An unprecedented Pt-catalysed cyclisation of N-tethered 1,5-bisallenes in the presence of oxygen nucleophiles is reported, where formation of 6- or 7-membered rings is driven by the choice of nucleophile and the mechanism dictated by the nucleophile and the electronic properties of the bisallene. The reaction in the presence of alcohols gives preferentially vinyltetrahydropyridines with an extra alkoxy group and Pt-H as the active species in the catalytic cycle, while formation of di- and tetrahydroazepines with an extra hydroxyl group is favoured when water is used as nucleophile, via nucleophilic attack/carbocyclization as the favoured pathway. The products obtained are frequently found in the core of natural products with important biological activities, so understanding this complex mechanistic behaviour and exploiting this new methodology will have a big impact in organic synthesis and organometallic chemistry
Investigating the role of CNAG_05113 in the carnitine biosynthesis pathway in \u3ci\u3eCryptococcus neoformans.\u3c/i\u3e
Cryptococcus neoformans, the leading cause of fungal meningitis, is a fungal pathogen that causes severe infection of the central nervous system in patients with compromised immune systems, typically caused by HIV/AIDS. C. neoformans infections are present in developed countries including the United States, but most fatalities occur in sub-Saharan Africa where antiretroviral therapy, the treatment for HIV/AIDS, is less accessible. Current treatments for severe cryptococcal infections are extensive and outdated. There is a critical need for an improved understanding of the fungus and new targeted therapies. Our goal is to identify metabolic pathways important to the survival of C. neoformans in the human host that can then be targeted for the development of new antifungal reagents. Lung alveolar macrophages, which present a first line of host defense against C. neoformans infection, provide a glucose- and amino acid-poor environment, and nonpreferred carbon sources such as lactate and acetate are likely important early in establishment of a pulmonary infection. Utilizing a genetic screen performed by a graduated PhD student in my lab to identify genes necessary for growth on acetate, we have discovered that the last step of carnitine biosynthesis is required. Our goal was to identify other steps of the carnitine biosynthetic pathway. Using the amino acid sequence of the fungal Candida albicans 4-trimethylaminobutyraldehyde dehydrogenase (TMABADH), the third enzyme of the carnitine biosynthesis pathway which converts 4-trimethylaminobutyraldehyde (TMABA) to gamma-butyrobetaine (γBB), we identified CNAG_05113 as the encoding gene in C. neoformans. Using a strain in which the CNAG_05113 gene was deleted, the mutant was tested for growth and virulence deficiencies. CNAG_05113 cells have inhibited growth in conditions with acetate as the sole carbon source. When reintroduced to carnitine and carnitine pathway intermediates, growth of mutant cells was restored. These results indicate that CNAG_05113 encodes the third step in carnitine biosynthesis. Future research is to identify the genes encoding other steps of the carnitine biosynthesis pathway and to biochemically characterize the encoded enzymes
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