1,172 research outputs found
Solar power satellite rectenna design study: Directional receiving elements and parallel-series combining analysis
Rectenna conversion efficiencies (RF to dc) approximating 85 percent were demonstrated on a small scale, clearly indicating the feasibility and potential of efficiency of microwave power to dc. The overall cost estimates of the solar power satellite indicate that the baseline rectenna subsystem will be between 25 to 40 percent of the system cost. The directional receiving elements and element extensions were studied, along with power combining evaluation and evaluation extensions
Extending Qualitative Spatial Theories with Emergent Spatial Concepts: An Automated Reasoning Approach
Qualitative Spatial Reasoning is an exciting research field of the
Knowledge Representation and Reasoning paradigm whose application often requires
the extension, refinement or combination of existent theories (as well as
the associated calculus). This paper addresses the issue of the sound spatial interpretation
of formal extensions of such theories; particularly the interpretation
of the extension and the desired representational features. The paper shows how
to interpret certain kinds of extensions of Region Connection Calculus (RCC)
theory. We also show how to rebuild the qualitative calculus of these extensions.Junta de Andalucía TIC-606
Comparative performance of diffused junction indium phosphide solar cells
A comparison is made between indium phosphide solar cells whose p-n junctions were processed by open tube capped diffusion, and closed tube uncapped diffusion, of sulfur into Czochralski grown p-type substrates. Air mass zero, total area, efficiencies ranged from 10 to 14.2 percent, the latter value attributed to cells processed by capped diffusion. The radiation resistance of these latter cells was slightly better, under 1 MeV electron irradiation. However, rather than being process dependent, the difference in radiation resistance could be attributed to the effects of increased base dopant concentration. In agreement with previous results, both cells exhibited radiation resistance superior to that of gallium arsenide. The lowest temperature dependency of maximum power was exhibited by the cells prepared by open tube capped diffusion. Contrary to previous results, no correlation was found between open circuit voltage and the temperature dependency of Pmax. It was concluded that additional process optimization was necessary before concluding that one process was better than another
Air quality modelling as a tool for sustainable urban traffic management
This work intends to assess the impact of road traffic management on urban air quality at the street level. At the core of the applied methodology is the numerical modelling of wind flow and air pollutants dispersion in a typical European urban environment. Through the application of a Computational Fluid Dynamics (CFD) model, the synergies between the 3D configuration of the street-canyon, in addition to the impacts on the dispersion of CO and PM10 emitted by vehicles, were evaluated. Air quality simulations were performed for a study domain of approximately 2501000 m2 in the downtown of a medium sized Portuguese town, with average daily traffic of 21,400 vehicles. Different traffic scenarios were analysed based on the modification of the number and location of traffic lanes for typical meteorological boundary conditions. Complex dispersion patterns were obtained due to the effect of buildings and trees on the wind flow. Moreover, simulations for the different scenarios have shown distinct behaviours of the air pollutants due to the prevailing wind direction and road positioning. It was concluded that, for typical conditions, the closure of the two traffic lanes located on the south side of the main avenue and the two adjacent streets is the best solution for air quality improvement. This scenario leads to a 31% reduction in CO and PM10 concentrations on the North sidewalk and 81% on the South sidewalk when comparing to present conditions. The other alternative leads to a reduction of, respectively, 70% and 20%. The first scenario also leads to maximum decreases of 57% and 59%, respectively, in the CO and PM10 peak concentrations. These conclusions stress the importance of integrating the knowledge provided by the application of CFD models in urban planning and road traffic management with the goal of promoting urban sustainability.publishe
Revisiting the genus Photobacterium: taxonomy, ecology and pathogenesis
The genus Photobacterium, one of the eight genera included in the family Vibrionaceae, contains 27 species with valid names and it has received attention because of the bioluminescence and pathogenesis mechanisms that some of its species exhibit. However, the taxonomy and phylogeny of this genus are not completely elucidated; for example, P. logei and P. fischeri are now considered members of the genus Aliivibrio, and previously were included in the genus Vibrio. In addition, P. damselae subsp. piscicida was formed as a new combination for former Vibrio damsela and Pasteurella piscicida. Moreover, P. damselae subsp. damselae is an earlier heterotypic synonym of P. histaminum. To avoid these incovenences draft and complete genomic sequences of members of Photobacterium are increasingly becoming available and their use is now routine for many research laboratories to address diverse goals: species delineation with overall genomic indexes, phylogenetic analyses, comparative genomics, and phenotypic inference. The habitats and isolation source of the Photobacterium species include seawater, sea sediments, saline lake waters, and a variety of marine organisms with which the photobacteria establish different relationships, from symbiosis to pathogenic interactions. Several species of this genus contain bioluminescent strains in symbiosis with marine fish and cephalopods; in addition, other species enhance its growth at pressures above 1 atmosphere, by means of several high-pressure adaptation mechanisms and for this, they may be considered as piezophilic (former barophilic) bacteria. Until now, only P. jeanii, P. rosenbergii, P. sanctipauli, and the two subspecies of P. damselae have been reported as responsible agents of several pathologies on animal hosts, such as corals, sponges, fish and homeothermic animals. In this review we have revised and updated the taxonomy, ecology and pathogenicity of several members of this genus. [Int Microbiol 20(1): 1-10 (2017)]Keywords: Photobacterium · taxonomy · symbiosis · pathogenesis · virulence factor
Combined use of a new SNP-based assay and multilocus SSR markers to assess genetic diversity of Xylella fastidiosa subsp. pauca infecting citrus and coffee plants
Two haplotypes of Xylella fastidiosa subsp. pauca (Xfp) that correlated with their host of origin were identified in a collection of 90 isolates infecting citrus and coffee plants in Brazil, based on a single-nucleotide polymorphism in the gyrB sequence. A new single-nucleotide primer extension (SNuPE) protocol was designed for rapid identification of Xfp according to the host source. The protocol proved to be robust for the prediction of the Xfp host source in blind tests using DNA from cultures of the bacterium, infected plants, and insect vectors allowed to feed on Xfp-infected citrus plants. AMOVA and STRUCTURE analyses of microsatellite data separated most Xfp populations on the basis of their host source, indicating that they were genetically distinct. The combined use of the SNaPshot protocol and three previously developed multilocus SSR markers showed that two haplotypes and distinct isolates of Xfp infect citrus and coffee in Brazil and that multiple, genetically different isolates can be present in a single orchard or infect a single tree. This combined approach will be very useful in studies of the epidemiology of Xfp-induced diseases, host specificity of bacterial genotypes, the occurrence of Xfp host jumping, vector feeding habits, etc., in economically important cultivated plants or weed host reservoirs of Xfp in Brazil and elsewhere [Int Microbiol 2015; 18(1):13-24]Keywords: Citrus variegated chlorosis · coffee leaf scorch · vector transmission· xylem-limited bacteria · haplotype characterization · host-plant associatio
In silico scrutiny of genes revealing phylogenetic congruence with clinical prevalence or tropism properties of Chlamydia trachomatis strains
Microbes possess a multiplicity of virulence factors that confer them the ability to specifically
infect distinct biological niches. Contrary to what is known for other bacteria, for the obligate intracellular
human pathogen Chlamydia trachomatis, the knowledge of the molecular basis underlying serovars’ tissue
specificity is scarce. We examined all ~900 genes to evaluate the association between individual phylogenies
and cell-appetence or ecological success of C. trachomatis strains. Only ~1% of the genes presented a tree
topology showing the segregation of all three disease groups (ocular, urogenital, and lymphatic) into three wellsupported
clades. Approximately 28% of the genes, which include the majority of the genes encoding putative
type III secretion system effectors and Inc proteins, present a phylogenetic tree where only lymphogranuloma
venereum strains form a clade. Similarly, an exclusive phylogenetic segregation of the most prevalent genital
serovars was observed for 61 proteins. Curiously, these serovars are phylogenetically cosegregated with the
lymphogranuloma venereum serovars for ~20% of the genes. Some clade-specific pseudogenes were identified
(novel findings include the conserved hypothetical protein CT037 and the predicted a-hemolysin CT473),
suggesting their putative expendability for the infection of particular niches. Approximately 3.5% of the genes
revealed a significant overrepresentation of nonsynonymous mutations, and the majority encode proteins that
directly interact with the host. Overall, this in silico scrutiny of genes whose phylogeny is congruent with clinical
prevalence or tissue specificity of C. trachomatis strains may constitute an important database of putative targets
for future functional studies to evaluate their biological role in chlamydial infections.This work was supported by a grant, ERA-PTG/0004/2010, from
Fundação para a Ciência e a Tecnologia (FCT) (to J.P.G.), in the frame
of ERA-NET PathoGenoMics. A.N. is recipient of a FCT post-doctoral
fellowship (SFRH/BPD/75295/2010), V.B. and R.F. are recipients of
Ph.D. fellowships (SFRH/BD/68527/2010 and SFRH/BD/68532/2010,
respectively) from FCT, and V.D. is a recipient of fellowship on behalf
of the grant ERA-PTG/0004/2010
Development process and cognitive testing of CARATkids - Control of Allergic Rhinitis and Asthma Test for children
Funding Information: The authors would like to thank the children and caregivers and the physicians that participated in the study and the Sociedade Portuguesa de Alerglogia e Imunologia Clínica and Associação Portuguesa de Asmáticos e Alérgicos for the help and support the CARAT project. The consensus meetings had logistic and unrestricted financial support from MSD Portugal.Background: Allergic rhinitis and asthma (ARA) are chronic inflammatory diseases of the airways that often coexist in children. The only tool to assess the ARA control, the Control of Allergic Rhinitis and Asthma Test (CARAT) is to be used by adults. We aimed to develop the Pediatric version of Control of Allergic Rhinitis and Asthma Test (CARATkids) and to test its comprehensibility in children with 4 to 12 years of age.Methods: The questionnaire development included a literature review of pediatric questionnaires on asthma and/or rhinitis control and two consensus meetings of a multidisciplinary group. Cognitive testing was carried out in a cross-sectional qualitative study using cognitive interviews.Results: Four questionnaires to assess asthma and none to assess rhinitis control in children were identified. The multidisciplinary group produced a questionnaire version for children with 17 questions with illustrations and dichotomous (yes/no) response format. The version for caregivers had 4-points and dichotomous scales. Twenty-nine children, 4 to 12 years old, and their caregivers were interviewed. Only children over 6 years old could adequately answer the questionnaire. A few words/expressions were not fully understood by children of 6 to 8 years old. The drawings illustrating the questions were considered helpful by children and caregivers. Caregivers considered the questionnaire complete and clear and preferred dichotomous over the 4-points scales. The proportion of agreement between children and their caregivers was 61%. The words/expressions that were difficult to understand were amended.Conclusion: CARATkids, the first questionnaire to assess a child's asthma and rhinitis control was developed and its content validity was assured. Cognitive testing showed that CARATKids is well-understood by children 6 to 12 years old. The questionnaire's measurement properties can now be assessed in a validation study.publishersversionpublishe
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RF/Microwave Non-Destructive Measurements of Electrical Properties of Semiconductor Wafers for Thermophotovoltaic Applications
A radio-frequency/microwave measurement system has been designed for non-contacting determination of sheet resistance and excess carrier lifetime of low-bandgap materials and junctions, specifically GaSb-based alloys for thermophotovoltaic (TPV) applications. The design incorporates RF circuitry in the 100--500 MHz frequency range and utilizes a Q-switched YAG laser at 1.32 microns to photo-generate electron-hole pairs and conductivity modulate the material and/or junction under test. Supplementary measurements with a GaAs pulsed diode laser at 904 nm provides a faster transient response with near-surface photogeneration. Initial measurements on GaSb substrates, Zn-diffused materials and epitaxially grown layers are presented and discussed
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