183 research outputs found
The influence of gibberellic acid and paclobutrazol on induction of somatic embryogenesis in wild type and hairy root cultures of Centaurium erythraea Gillib.
The effects of exogenous gibberellic acid (GA3) and paclobutrazol on induction of somatic embryos in wild type and hairy root culture of Centaurium erythraea Gillib. were investigated. Both compoundswere incorperated into 1/2 MS medium at 6 concentrations (0.01, 0.03, 0.1, 0.3, 1.0 and 3.0 ìM). Wild type root and hairy root explants cultured in the presence of GA3 at all tested concentrations under 16-h photoperiod or in the darkness decreased the number of somatic embryos that were produced. Paclobutrazol (0.3 mM) induced the largest number (19.7, 16.5) of somatic embryos in wild type and hairy root cultures, respectively. Rooting of plants derived from somatic embryos as achieved on ½MSmedium. These results indicate that paclobutrazol is beneficial for somatic embryo induction and formation in wild type and hairy root culture
Reaction and proton-removal cross sections of Li, Be, B, C, ^{12N, O and Ne on Si at 15 to 53 MeV/nucleon
Excitation functions for total reaction cross sections, , were
measured for the light, mainly proton-rich nuclei Li, Be, B,
C, N, O, and Ne incident on a Si telescope
at energies between 15 and 53 MeV/nucleon. The telescope served as target,
energy degrader and detector. Proton-removal cross sections, for
Ne and for most of the other projectiles, were also measured.
The strong absorption model reproduces the -dependence of , but
not the detailed structure. Glauber multiple scattering theory and the JLM
folding model provided improved descriptions of the measured values.
radii, extracted from the measured using the optical limit of
Glauber theory, are in good agreement with those obtained from high energy
data. One-proton removal reactions are described using an extended Glauber
model, incorporating second order noneikonal corrections, realistic single
particle densities, and spectroscopic factors from shell model calculations.Comment: 16 pages, 6 figure
Search for the Production of Element 112 in the 48Ca + 238U Reaction
We have searched for the production of element 112 in the reaction of 231 MeV
48Ca with 238U. We have not observed any events with a "one event" upper limit
cross section of 1.6 pb for EVR-fission events and 1.8 pb for EVR-alpha events.Comment: 6 pages, 3 figures, submitted to Phys. Rev.
Positron and positronium annihilation patterns in zeolites and bulk ceramics
Positron lifetime (LT) measurements have revealed that in porous media the annihilation pattern is probably dominated by a near-saturation level trapping both for the positron and the positronium as well, which masks the contribution from the ldquofree annihilationrdquo, i.e., annihilation from delocalised positrons. In this work we compare positron lifetime spectra of crystalline zeolites with bulk ceramic materials fabricated by sintering from the same constituents as the zeolites and analyse common features and differences between them. For the dense ceramic samples the contribution from long-living components to the annihilation pattern is substantially lower than that for the zeolites. The results are analysed with the aim to extract new knowledge for the zeolites and for the sensitivity limits for free volume studies in ceramics. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Integrated system for traction and battery charging of electric vehicles with universal interface to the power grid
This paper proposes an integrated system for traction and battery charging of electric vehicles (EVs) with universal interface to the power grid. In the proposed system, the power electronics converters comprising the traction drive system are also used for the battery charging system, reducing the required hardware, meaning the integrated characteristic of the system. Besides, this interface is universal, since it can be performed with the three main types of power grids, namely: (1) Single-phase AC power grids; (2) Three-phase AC power grids; (3) DC power grids. In these three types of interfaces with the power grid, as well as in the traction drive operation mode, bidirectional operation is possible, framing the integration of this system into an EV in the context of smart grids. Moreover, the proposed system endows an EV with an on-board fast battery charger, whose operation allows either fast or slow battery charging. The main contributes of the proposed system are detailed in the paper, and simulation results are presented in order to attain the feasibility of the proposed system.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT -Fundacao para a Ciencia e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work has been supported by FCT within the Project Scope DAIPESEV - Development of Advanced Integrated Power Electronic Systems for Electric Vehicles: PTDC/EEI-EEE/30382/2017. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency. This work is part of the FCT project 0302836 NORTE-01-0145-FEDER-030283
Design of a UMTS/GPRS Assisted Mesh Network (UAMN)
Wireless Mesh or multi-hop networks (WMNs) are well known thanks to its simplicity on deployment and the lack of infrastructure. These two advantages come with some drawbacks. WMNs have limitations with the support of Quality of Service (QoS), they do not assure coverage or even connectivity, and security, management and monitoring are not considered key requirements. In order to benefit of mesh networks and use them as an operator graded network, it is necessary to either improve mesh networks to fulfill all these requirements or use an alternative network that offers full availability, connectivity and security to assist the mesh network. Considering the two options, the second is the one selected making use of GPRS/UMTS as an assistant network.
The document describes a set of requirements and the design of the functionalities needed to build an operator graded network using the cellular GPRS/UMTS. The aspects covered in the design are: security, quality of service, mobility, self configuration and optimization. The last point, optimization, is not directly involved with mesh networking, but it is an improvement easy to achieve when using a gateway node to access the Internet through a GPRS/UMTS connection. The design of the solution not only considers functionality, but also feasibility employing of the shelve elements. The mesh nodes and gateways are built on top of Linux operating system with the aim to reuse previous results and open source software. The final objective of the project is to build a usable system to be used as a proof of concept.Peer Reviewe
Environmental governance in a contested state:the influence of European Union and other external actors on energy sector regulation in Kosovo
This article examines environmental governance in Kosovo, with a particular focus on the energy sector. The article considers the degree to which the emerging model of environmental governance is characterised by hierarchical and non-hierarchical modes of coordination. We examine the roles of a number of domestic institutions and actors – ministries, agencies, and regulatory bodies– and the influence of external actors, including the EU, the US, and Serbia. The EU is building Kosovo’s own hierarchical governance capacity by strengthening domestic institutions, whilst the US focuses primarily on market liberalization, whilst simultaneously supporting EU efforts. Moreover, environmental policy change is not wholly or predominantly driven by domestic actors, which can partly be attributed to Kosovo’s limited domestic sovereignty. We conclude that the emerging model of environmental governance in Kosovo is characterized by a weak hierarchy, partly as a result of external actor involvement, which disincentivises the government from responding to domestic non-state actor pressure
Neutron-rich fragments produced by in-flight fission of U-238
The production cross sections of neutron-rich fission residues in reactions induced by U-238 projectiles at 950A MeV impinging on Pb and Be targets are investigated at the Fragment Separator at GSI. These two targets allow us to investigate fission processes induced by two reaction mechanisms, Coulomb and nuclear excitations, and to study the role of these mechanisms in the neutron excess of the final fragments.Peer reviewe
Avoiding obscure topics and generalising findings produces higher impact research
Much academic research is never cited and may be rarely read, indicating wasted effort from the authors, referees and publishers. One reason that an article could be ignored is that its topic is, or appears to be, too obscure to be of wide interest, even if excellent scholarship produced it. This paper reports a word frequency analysis of 874,411 English article titles from 18 different Scopus natural, formal, life and health sciences categories 2009-2015 to assess the likelihood that research on obscure (rarely researched) topics is less cited. In all categories examined, unusual words in article titles associate with below average citation impact research. Thus, researchers considering obscure topics may wish to reconsider, generalise their study, or to choose a title that reflects the wider lessons that can be drawn. Authors should also consider including multiple concepts and purposes within their titles in order to attract a wider audience
European Respiratory Society guidelines for the management of adult bronchiectasis
Bronchiectasis in adults is a chronic disorder associated with poor quality of life and frequent exacerbations in many patients. There have been no previous international guidelines.The European Respiratory Society guidelines for the management of adult bronchiectasis describe the appropriate investigation and treatment strategies determined by a systematic review of the literature.A multidisciplinary group representing respiratory medicine, microbiology, physiotherapy, thoracic surgery, primary care, methodology and patients considered the most relevant clinical questions (for both clinicians and patients) related to management of bronchiectasis. Nine key clinical questions were generated and a systematic review was conducted to identify published systematic reviews, randomised clinical trials and observational studies that answered these questions. We used the GRADE approach to define the quality of the evidence and the level of recommendations. The resulting guideline addresses the investigation of underlying causes of bronchiectasis, treatment of exacerbations, pathogen eradication, long term antibiotic treatment, anti-inflammatories, mucoactive drugs, bronchodilators, surgical treatment and respiratory physiotherapy.These recommendations can be used to benchmark quality of care for people with bronchiectasis across Europe and to improve outcomes
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