17 research outputs found

    A genomic survey of the fish parasite Spironucleus salmonicida indicates genomic plasticity among diplomonads and significant lateral gene transfer in eukaryote genome evolution

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    BACKGROUND: Comparative genomic studies of the mitochondrion-lacking protist group Diplomonadida (diplomonads) has been lacking, although Giardia lamblia has been intensively studied. We have performed a sequence survey project resulting in 2341 expressed sequence tags (EST) corresponding to 853 unique clones, 5275 genome survey sequences (GSS), and eleven finished contigs from the diplomonad fish parasite Spironucleus salmonicida (previously described as S. barkhanus). RESULTS: The analyses revealed a compact genome with few, if any, introns and very short 3' untranslated regions. Strikingly different patterns of codon usage were observed in genes corresponding to frequently sampled ESTs versus genes poorly sampled, indicating that translational selection is influencing the codon usage of highly expressed genes. Rigorous phylogenomic analyses identified 84 genes – mostly encoding metabolic proteins – that have been acquired by diplomonads or their relatively close ancestors via lateral gene transfer (LGT). Although most acquisitions were from prokaryotes, more than a dozen represent likely transfers of genes between eukaryotic lineages. Many genes that provide novel insights into the genetic basis of the biology and pathogenicity of this parasitic protist were identified including 149 that putatively encode variant-surface cysteine-rich proteins which are candidate virulence factors. A number of genomic properties that distinguish S. salmonicida from its human parasitic relative G. lamblia were identified such as nineteen putative lineage-specific gene acquisitions, distinct mutational biases and codon usage and distinct polyadenylation signals. CONCLUSION: Our results highlight the power of comparative genomic studies to yield insights into the biology of parasitic protists and the evolution of their genomes, and suggest that genetic exchange between distantly-related protist lineages may be occurring at an appreciable rate in eukaryote genome evolution

    Continuous stand-alone controllable aerosol/cloud droplet dryer for atmospheric sampling

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    We describe a general-purpose dryer designed for continuous sampling of atmospheric aerosol, where a specified relative humidity (RH) of the sample flow (lower than the atmospheric humidity) is required. It is often prescribed to measure the properties of dried aerosol, for instance for monitoring networks. The specific purpose of our dryer is to dry cloud droplets (maximum diameter approximately 25 mu m, highly charged, up to 5x10(2) charges). One criterion is to minimise losses from the droplet size distribution entering the dryer as well as on the residual dry particle size distribution exiting the dryer. This is achieved by using a straight vertical downwards path from the aerosol inlet mounted above the dryer, and removing humidity to a dry, closed loop airflow on the other side of a semi-permeable GORE-TEX membrane (total area 0.134m(2)). The water vapour transfer coefficient, k, was measured to be 4.6x10(-7) kgm(-2) s(-1) % RH-1 in the laboratory (temperature 294 K) and is used for design purposes. A net water vapour transfer rate of up to 1.2x10(-6) kg s-1 was achieved in the field. This corresponds to drying a 5.7 L min(-1) (0.35m(3) h(-1)) aerosol sample flow from 100% RH to 27% RH at 293K (with a drying air total flow of 8.7 L min-1). The system was used outdoors from 9 May until 20 October 2010, on the mountain Brocken (51.80 degrees N, 10.67 degrees E, 1142ma.s.l.) in the Harz region in central Germany. Sample air relative humidity of less than 30% was obtained 72% of the time period. The total availability of the measurement system was > 94% during these five months

    Building performance based on measured data

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    With increasing liability for builders, the need for evaluation methods that focuses on the building’s performance and thus excludes the impact from residents’ behavior increases. This is not only of interest for new buildings but also when retrofitting existing buildings in order to reduce energy end-use. The investigation in this paper is based on extensive measurements on two fairly representative type of buildings, a single family building in Ekerö, Stockholm built 2000 and two apartment buildings in Umeå (1964) in order to extract key energy performance parameters such as the building’s heat loss coefficient, heat transfer via the ground and heat gained from the sun and used electricity. With access to pre-processed daily data from a 2-month periods, located close to the winter solstice, a robust estimate of the heat loss coefficient was obtained based on a regression analysis. For the single family building the variation was within 1% and for the two heavier apartment buildings an average variation of 2%, with a maximum of 4%, between different analyzed periods close to the winter solstice. The gained heating from the used electricity in terms of a gain factor could not be unambiguously extracted and therefore could only a range for the heat transfer via ground be estimated. The estimated range for the transfer via ground for the two apartment buildings were in very good agreement with those calculated according to EN ISO 13 370 and corresponded to almost 10% of the heating demand at the design temperature. For the single family building with an insulated slab and parts of the walls below ground level, the calculations gave slightly higher transfer than what was obtained from the regression analysis. For the estimated gained solar radiation no comparison has been possible to make, but the estimated gain exhibited an expected correlation with the global solar radiation data that was available for the two apartment buildings

    Development of an H-TDMA for long-term unattended measurement of the hygroscopic properties of atmospheric aerosol particles

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    A new hygroscopic tandem differential mobility analyzer (H-TDMA) has been constructed at Lund University within the frameworks of the EU FP6 Infrastructure Project EUSAAR (www.eusaar.org). The aim of this coordinated H-TDMA development is to design and evaluate a new generation of H-TDMAs that are capable of conducting long term measurements of the hygroscopic growth and state of mixing of sub-micrometer atmospheric aerosol particles at the EUSAAR aerosol super-sites across Europe. The H-TDMA constructed for this project has been validated with respect to hygroscopic growth factor, stability of relative humidity (RH), temperature stability and its ability to operate unattended for longer periods of time. When measuring growth factors of ammonium sulphate, the new H-TDMA system was found to measure within a growth factor deviation of +/- 0.05 compared to previously recorded data by Tang et al. (1994). The long term RH of the system has been found stable at 90.0% with a standard deviation of +/- 0.23% and an average temperature variability of the second DMA less than +/- 0.1 K. Daily automated ammonium sulphate measurements have validated the ambient measurements. The instrument is operated at the EMEP/EUSAAR background station Vavihill in the southern part of Sweden

    Funktionskriterier för vägkonstruktioner : Förstudie

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    Det projekt som här rapporteras har som syfte att identifiera och beskriva de svårigheter och möjligheter som totalentreprenader medför, respektive erbjuder, för alla parter. Målet är att utveckla totalentreprenader på ett sådant sätt att branschens effektivitet ökas. Denna rapport är en förstudie där det studerats vilka krav som byggherren ska ställa på utföraren av en vägkonstruktion i en totalentreprenad med funktionsansvar och hur utföraren ska verifiera kraven. Arbetet har genomförts med medlemmar från olika aktörer i branschen och omfattat främst litteraturstudier och intervjuer. Kunskaper och erfarenheter har sammanställts och analyserats för att slutligen kondenseras ned till ett antal förslag till fortsatt arbete. Förstudien har pekat ut ett antal områden som viktiga för att påskynda framtida utveckling av totalentreprenader: Terminologi \u96 idag råder viss begreppsförvirring Analys av funktionella krav i tidigare projekt Trafikantkrav Miljökrav Utveckling av funktionella krav i samverkan Väghållarekonomi Regelbetingade begränsningar av funktionella krav Uppföljning och underlättande av erfarenhetsackumulering Implementering av nya mått och mätmetoderSBUF Projekt nr 1228

    An Approach for Realistic Simulation of Real Road Condition in a Moving Base Driving Simulator

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    With today's advanced measurement equipment for monitoring road condition, it is possible to measure road geometry at high precision within a large span of wavelengths. Detailed information about the roads' longitudinal and lateral profiles, including macro texture, would in theory be sufficient for a realistic reproduction of road induced vibration and noise in a driving simulator. Especially, it would be possible to create a direct connection between the visual information of the road condition and the ride experience, which would increase the level of realism in the simulation. VTI has, during three years, performed an internal project called SHAKE with the aim to develop and implement models in VTI driving simulator III that use measured road data for generating realistic vibrations and audible road noise connected to the visual impression presented on the projection screen. This has indeed resulted in a more realistic driving experience, and a validation study with test persons driving both in the simulator and in the field has been undertaken. The OpenDRIVE standard is used as a framework for describing the road properties (e.g., visual, vibrations, and noise). For this purpose, some augmentations to the OpenDRIVE standard had to be made. This paper describes the technical implementations in the driving simulator, along with results from test drives on the implemented road sections

    Improving the realism in the VTI driving simulators : Shake final report

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    Väg- och transportforskningsinstitutet (VTI) har tre avancerade körsimulatorer med rörelsesystem. Syftet med detta projekt var att utveckla och implementera nya modeller för grafik, vibrationer och buller, allt i syfte att öka realismen för föraren i simulatorn. Vidare skulle en valideringsstudie genomföras. Inom ramen för projektet uppnåddes följande: Utveckling av ett nytt grafiskt programpaket \u95Förbättring av modellerna för vibrationer på grund av däck/väg \u95Förbättring av rörelsesystemet genom förskjutning av rotationscentrum \u95Förbättring av modulen för buller, genom återskapande av däck- och vägbuller. \u95Synkronisering mellan vägytans grafiska presentation, buller och vibrationer . Modellernas validitet testades i VTI:s simulator III. Statistisk testning av skillnader mellan verklig bil och simulator indikerade absolut validitet för subjektiva bedömningar av vägytans jämnhet och tysthet och för det objektiva måttet hastighet, med undantag av områden där hastighetsgränsen ändrades. I dessa områden erhölls endast relativ validitet eftersom både accelerationer och retardationer var snabbare i simulatorn än i verklig bil. Relativ validitet indikerades också för det subjektiva måttet generell komfort. Resultaten från de olika valideringarna visar att förbättringarna har varit framgångsrika och föraren i simulatorn kan nu se, höra och känna ojämnheter i vägbanan exakt när hjulen träffar dessa. Fortfarande återstår dock många möjligheter till ytterligare förbättringar i simulatormodellerna.The Swedish Road and Transport Research Institute (VTI) has three advanced moving base driving simulators. The aim of this project was to develop and implement new models concerning vibration, noise and graphics in order to improve the realism in the simulators. Moreover, a validation study was to be conducted. Within the frame of the project the following were achieved: improvement of the tyre/road vibration models, \u95improvement of the motion system by changing the rotation centre, \u95improvement of the noise module facilitating reproduction of noise from tyre/road, \u95synchronization of the impressions from graphics, noise and vibrations caused by the road surface. The validity of the models was tested in the VTI Simulator III. Statistical testing of differences between the car and the simulator indicated absolute validity for the subjective ratings of evenness and noise level and the objective measure speed, with the exception of areas surrounding speed limit signs where only relative validity was found. Relative validity was also indicated for the variable overall comfort. The results from the different validations show that the improvements have been successful and the driver in the simulator can now see, hear and feel the sensation of any road surface irregularities exactly when the wheels hit that part of the road. However, several improvements in the simulator models can still be desired
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