663 research outputs found

    Impact of super absorbent polymers on early age behavior of ultra-high performance concrete walls

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    Early age cracking, a common problem for Ultra-High Performance Concrete (UHPC), is caused by Autogenous Shrinkage (AS) and self-desiccation arising from the chemical shrinkage during the cement hydration reactions when the deformation is restrained. However, to avoid the crack development initiated by AS, several solutions can be adopted; one example is the addition of a promising material, considered as an internal curing agent, the Super Absorbent Polymers (SAP) which limits the capillary depressions that can enhance the formation of the crack. In this study the main goal is to mitigate the shrinkage using SAPs in infrastructure under severe conditions. Therefore, a demonstrator wall was built simulating a typical case with high risk of cracking. With the help of fiber optic SOFO sensors embedded in the wall, real-time deformations are recorded and compared the demountable mechanical strain gauges (DEMEC) measurements to further investigate the behavior of SAPs in real scale infrastructure. The amount of extra water (in SAP) needed to mitigate shrinkage was determined by performing chemical shrinkage tests on different cement paste combinations. Tests of autogenous shrinkage were performed on mortars using corrugated tubes and showed that SAPs reduce to some extent the AS. Under restrained conditions via ring tests, SAP specimens did not crack. Therefore, SAPs were found promising towards mitigating the shrinkage and enhancing the early age behavior of concrete for a better durability

    Hvorfor øve?

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    Master`s thesis in Risk Management and Societal SafetySammendrag Kravet om kontinuerlig og systematisk læring og forbedring i virksomheter kom med Internkontrollforskriften i 1996. Kravet gjelder alle virksomheter, både private og offentlige, og omfatter også sikkerhet og sikkerhetsforståelse i samfunnet generelt og for den enkelte virksomhet. Utarbeidelse av risiko- og sårbarhetsanalyser skal gjenspeile den aktuelle virksomhets eller samfunnets satsingsområder. For et brannvesen vil en slik analyse være grunnleggende for å kunne si noe om hvor innsatsen skal prioriteres også når det gjelder forberedende aktiviteter som øvelser. Brannvesenet er pålagt en viss øvelsesfrekvens på enkelte fagområder, men øver i tillegg på områder og hendelser som erfaringsvis er definert som aktuelle risikoområder lokalt. Utgangspunktet for oppgaven var å se på hvordan øvelsene førte til endringer i praksis og erfaringsoverføring mellom de ulike vaktlagene. Rogaland brann og redning IKS (Interkommunale samarbeid) er et av landets største brannvesen. Forventningen var at virksomheten med sin strukturerte øvelsesplan ville ha fokus på evaluering av hver enkelt øvelse som så ble lagt til grunn for en kontinuerlig læringsprosess og videre prioritering av øvelsesområder. Med utgangspunkt i ulike teoretiske perspektiv ble det gjennomført semistrukturerte intervjuer med personer med ulike funksjoner i Rogaland brann og redning IKS, i tillegg til å få være observatør under en øvelse. Intervjuene viste at brannvesenet har gode systemer for planlegging og gjennomføring av øvelser. Etterarbeidet med evaluering og implementering av ny læring forgår både formelt og uformelt, men empiriske funn viser også at virksomheten har et forbedringspotensial på dette området. Dette gjelder særlig fokus på implementering av ny erfaring etter øvelsene. Ønsket fra ledelsen er at læringen kan være mer styrt enn i dag. Det vil si at virksomheten skal ha mulighet til større kontroll over læringen, slik at den kan føre til en felles økt kompetanse. Slik øvelse foregår i dag, øker læringen for det enkelte vaktlag, men det blir mer tilfeldig om denne læringen kommer videre i organisasjonen og om den fører til endringer. Noe erfaringsoverføring skjer, det er innarbeidet nye rutiner for å styrke slik læring. Funnene viser at øvelsene som er lagt inn i årshjulet i stor grad gjennomføres for å vedlikeholde kompetanse, for å forbedre det som blir gjort og også for å lære om nye tema. Erfaringene fra hvert enkelt vaktlag etter øvelsene, blir i mindre grad videreført til andre vaktlag eller andre brigader

    Assessment of parameters describing representativeness of air quality in-situ measurement sites

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    The atmospheric layer closest to the ground is strongly influenced by variable surface fluxes (emissions, surface deposition) and can therefore be very heterogeneous. In order to perform air quality measurements that are representative of a larger domain or a certain degree of pollution, observatories are placed away from population centres or within areas of specific population density. Sites are often categorised based on subjective criteria that are not uniformly applied by the atmospheric community within different administrative domains yielding an inconsistent global air quality picture. A novel approach for the assessment of parameters reflecting site representativeness is presented here, taking emissions, deposition and transport towards 34 sites covering Western and Central Europe into account. These parameters are directly inter-comparable among the sites and can be used to select sites that are, on average, more or less suitable for data assimilation and comparison with satellite and model data. Advection towards these sites was simulated by backward Lagrangian Particle Dispersion Modelling (LPDM) to determine the sites' average catchment areas for the year 2005 and advection times of 12, 24 and 48 h. Only variations caused by emissions and transport during these periods were considered assuming that these dominate the short-term variability of most but especially short lived trace gases. The derived parameters describing representativeness were compared between sites and a novel, uniform and observation-independent categorisation of the sites based on a clustering approach was established. Six groups of European background sites were identified ranging from <i>generally remote</i> to more polluted <i>agglomeration</i> sites. These six categories explained 50 to 80% of the inter-site variability of median mixing ratios and their standard deviation for NO<sub>2</sub> and O<sub>3</sub>, while differences between group means of the longer-lived trace gas CO were insignificant. The derived annual catchment areas strongly depended on the applied LPDM and input wind fields, the catchment settings and the year of analysis. Nevertheless, the parameters describing representativeness showed considerably less variability than the catchment geometry, supporting the applicability of the derived station categorisation

    The association of microalbuminuria with mortality in patients with acute myocardial infarction. A ten-year follow-up study

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    Our study evaluates the long-term effect of microalbuminuria on mortality among patients with acute myocardial infarction. We followed 151 patients from 1996 to 2007 to investigate if microalbuminuria is a risk factor in coronary heart disease. All patients admitted with acute myocardial infarction in 1996 were included. At baseline, we recorded urinary albumin/creatinine concentration ratio, body mass index, blood pressure, left ventricle ejection fraction by echocardiography, smoking status, medication, diabetes, age, and gender. Deaths were traced in 2007 by means of the Danish Personal Identification Register. Microalbuminuria, defined as a urinary albumin/creatinine concentration ratio above 0.65 mg/mmoL, occurred in 50% of the patients and was associated with increased all-cause mortality. Thus, 68% of the patients with microalbuminuria versus 48% of the patients without microalbuminuria had died during the 10 years of follow-up (P=0.04). The crude hazard ratio for death associated with microalbuminuria was 1.78 (CI: 1.18–2.68) (P=0.006), whereas the gender- and age-adjusted hazard ratio was 1.71 (CI: 1.03–2.83) (P=0.04). We concluded that microalbuminuria in hospitalized patients with acute myocardial infarction is prognostic for increased long-term mortality. We recommend measurement of microalbuminuria to be included as a baseline risk factor in patients with acute myocardial infarction and in future trials in patients with coronary heart disease

    Formation of atomic tritium clusters and condensates

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    We present an extensive study of the static and dynamic properties of systems of spin-polarized tritium atoms. In particular, we calculate the two-body |F,m_F>=|0,0> s-wave scattering length and show that it can be manipulated via a Feshbach resonance at a field strength of about 870G. Such a resonance might be exploited to make and control a Bose-Einstein condensate of tritium in the |0,0> state. It is further shown that the quartet tritium trimer is the only bound hydrogen isotope and that its single vibrational bound state is a Borromean state. The ground state properties of larger spin-polarized tritium clusters are also presented and compared with those of helium clusters.Comment: 5 pages, 3 figure

    Deficits in Beam-Walking After Neonatal Motor Cortical Lesions are not Spared by Fetal Cortical Transplants in Rats

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    Adult rats that sustained unilateral motor cortical lesions at birth demonstrated deficits in traversing an elevated narrow beam. These deficits, manifested by hindlimb slips off the edge of the beam, were not spared in animals that received fetal cortical transplants into the lesion cavity immediately after lesion placement

    No influence of the polymorphisms CYP2C19 and CYP2D6 on the efficacy of cyclophosphamide, thalidomide, and bortezomib in patients with Multiple Myeloma

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    BACKGROUND: The response to treatment varies among patients with multiple myeloma and markers for prediction of treatment outcome are highly needed. Bioactivation of cyclophosphamide and thalidomide, and biodegradation of bortezomib, is dependent on cytochrome P450 metabolism. We explored the potential influence of different polymorphisms in the CYP enzymes on the outcome of treatment. METHODS: Data was analyzed from 348 patients undergoing high-dose treatment and stem cell support in Denmark in 1994 to 2004. Clinical information on relapse treatment in 243 individual patients was collected. The patients were genotyped for the non-functional alleles CYP2C19*2 and CYP2D6*3, *4, *5 (gene deletion), *6, and CYP2D6 gene duplication. RESULTS: In patients who were treated with bortezomib and were carriers of one or two defective CYP2D6 alleles there was a trend towards a better time-to-next treatment. We found no association between the number of functional CYP2C19 and CYP2D6 alleles and outcome of treatment with cyclophosphamide or thalidomide. Neither was the number of functional CYP2C19 and CYP2D6 alleles associated with neurological adverse reactions to thalidomide and bortezomib. CONCLUSION: There was no association between functional CYP2C19 and CYP2D6 alleles and treatment outcome in multiple myeloma patients treated with cyclophosphamide, thalidomide or bortezomib. A larger number of patients treated with bortezomib are needed to determine the role of CYP2D6 alleles in treatment outcome

    Evaluation of in situ measurements of atmospheric carbon monoxide at Mount Waliguan, China

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    Quasicontinuous measurements of carbon monoxide (CO) recorded over three years at Mount Waliguan (WLG), a global baseline station in remote western China, were examined using back trajectory analysis. The data include a revision to correct the working reference scale to the WMO2000 scale and corrections for drift in the reference gases. Between July 2004 and June 2007, CO exhibited large fluctuations and the 5 %, 50 % and 95 %-percentiles of relevant CO mixing ratios were 102 ppb, 126 ppb and 194 ppb. Approximately 50 % of all observed data were selected as CO background data using a mathematical procedure of robust local regression, with the remainder affected by regional-scale pollution. The monthly mean background CO mixing ratios showed a minimum in summer and a maximum in late winter, although all seasons were affected by short-term enhancements that exceeded background levels. The CO data were compared to values observed at the high alpine research station at Jungfraujoch, Switzerland. Smaller seasonal amplitudes were observed at WLG compared to the Jungfraujoch due to lower winter and spring CO levels, however, episodic enhancements of polluted air were greater at WLG. The air parcels arriving at WLG came predominately from the west, except in summer when advection from the east and southeast prevailed. Transport from the east or southeast typically brought polluted air to the site, having passed over populated urban areas upwind. A large number of elevated CO mixing ratios could also be associated with advection from the northwest of WLG via the central Xinjiang Uygur Autonomous Region (XUAR) and the Ge'ermu urban area where growing industrial activities as well as crops residue burning provide sources of CO. Air masses passing over northwestern Gansu were associated with relatively high CO values suggesting an anthropogenic influence, which was likely due to anthropogenic emissions from northwestern China (based on back-trajectory and potential source contribution analysis and on the INTEX-B: intercontinental Chemical Transport Experiment-Phase B). Background conditions were observed most frequently in air parcels from remote Tibet west of WLG. The probability that air parcels pass over regions of clean or polluted regions was further identified using potential source contribution function (PSCF) analysis
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