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Search Results: 1 - 10 of 209137 matches for " L. Rasmussen "
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Proceedings of a symposium on lions and leopards as game ranch animals, J. van Heerden (ed.) : book review
L. Rasmussen
Journal of the South African Veterinary Association , 2012, DOI: 10.4102/jsava.v69i1.812
Abstract:
Exercise-Induced Asthma Symptoms and Nighttime Asthma: Are They Similar to AHR?
V. Backer,L. M. Rasmussen
Journal of Allergy , 2009, DOI: 10.1155/2009/378245
Abstract: Background. Asthma experienced during exercise and during the night is based on the presence of airway hyperresponsiveness (AHR). The aim of the present study was to examine whether AHR is a predictor of exercise-induced asthma (EIA) and nighttime symptoms. Material. We included 793 asthmatics subjects with symptoms and a positive asthma test. Results. Mean (SD) FEV1 was 93% (15), 71% had rhinitis, and 62% had atopy. Both EIA and nighttime symptoms were associated with AHR; however, when including other factors of importance in a multivariate analysis, logRDR was eliminated, whereas FEV1% pred (<.001), smoking (<.05), atopy (<.001), sex (<.001), and treatment (<.01) were associated with having EIA while dyspnoea (<.001), cough (<.001), and eosinophils (<.01) were associated with frequent night symptoms. The risk of having nighttime awakenings due to asthma was more than twofold higher among those with EIA symptoms than among those without symptoms (OR (CI95%) 2.77 (2.0–3.8) (<.001)). In Conclusion. EIA and night symptoms are associated with AHR, but other factors of importance eliminated this close association. Night asthma is more closely associated with airway inflammation than AHR.
Technical Note: A comparison of model and empirical measures of catchment scale effective energy and mass transfer
C. Rasmussen,E. L. Gallo
Hydrology and Earth System Sciences Discussions , 2013, DOI: 10.5194/hessd-10-3027-2013
Abstract: Recent work suggests that a coupled energy and mass transfer term (EEMT), that includes the energy associated with effective precipitation and primary production, may serve as a robust prediction parameter of critical zone structure and function. However, the models used to estimate EEMT have been solely based on long term climatological data with little validation using point to catchment scale empirical data. Here we compare catchment scale EEMT estimates generated using two distinct approaches: (1) EEMT modelled using the established methodology based on estimates of monthly effective precipitation and net primary production derived from climatological data, and (2) empirical catchment scale EEMT estimated using data from 86 catchments of the Model Parameterization Experiment (MOPEX) and MOD17A3 annual net primary production (NPP) product derived from Moderate Resolution Imaging Spectroradiometer (MODIS). Results indicated positive and significant linear correspondence between model and empirical measures but with modelled EEMT values consistently greater than empirical measures of EEMT. Empirical catchment estimates of the energy associated with effective precipitation (EPPT) were calculated using a mass balance approach and base flow that accounts for water losses to quick surface runoff not accounted for in the climatologically modelled EPPT. Similarly, local controls on primary production such as solar radiation and nutrient limitation were not explicitly included in the climatologically based estimates of energy associated with primary production (EBIO) whereas these were captured in the remotely sensed MODIS NPP data. There was significant positive correlation between catchment aridity and the fraction of total energy partitioned into EBIO, where the EBIO increases as the average percentage catchment woody plant cover decreases. In summary, the data indicated strong correspondence between model and empirical measures of EEMT that agree well with catchment energy and water partitioning and plant cover.
Collapsing dynamics of attractive Bose-Einstein condensates
L. Berge,J. Juul Rasmussen
Physics , 2000, DOI: 10.1016/S0375-9601(02)01385-3
Abstract: The self-similar collapse of 3D and quasi-2D atom condensates with negative scattering length is examined. 3D condensates are shown to blow up following the scenario of {\it weak collapse}: The inner core of the condensate diverges with an almost zero particle number, while its tail distribution spreads out to large distances with a constant density profile. For this case, the 3-body recombination arrests the collapse, but it weakly dissipates the atoms. The confining trap then reforms the condensate at later times. In contrast, 2D condensates undergo a {\it strong collapse}: The atoms stay mainly located at center and recombination sequentially absorbs a significant amount of particles.
Responses of Macroinvertebrate Community Metrics to a Wastewater Discharge in the Upper Blue River of Kansas and Missouri, USA  [PDF]
Barry C. Poulton, Jennifer L. Graham, Teresa J. Rasmussen, Mandy L. Stone, Mandy L. Stone
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.715098
Abstract: The Blue River Main wastewater treatment facility (WWTF) discharges into the upper Blue River (725 km2), and is recently upgraded to implement biological nutrient removal. We measured biotic condition upstream and downstream of the discharge utilizing the macroinvertebrate protocol developed for Kansas streams. We examined responses of 34 metrics to determine the best indicators for discriminating site differences and for predicting biological condition. Significant differences between sites upstream and downstream of the discharge were identified for 15 metrics in April and 12 metrics in August. Upstream biotic condition scores were significantly greater than scores at both downstream sites in April (p = 0.02), and in August the most downstream site was classified as non-biologically supporting. Thirteen EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) considered intolerant of degraded stream quality were absent at one or both downstream sites. Increases in tolerance metrics and filtering macroinvertebrates, and a decline in ratio of scrapers to filterers all indicated effects of increased nutrient enrichment. Stepwise regressions identified several significant models containing a suite of metrics with low redundancy (R2 = 0.90 - 0.99). Based on the rapid decline in biological condition downstream of the discharge, the level of nutrient removal resulting from the facility upgrade (10% - 20%) was not enough to mitigate negative effects on macroinvertebrate communities.
On N=1 gauge models from geometric engineering in M-theory
A. Belhaj,L. B. Drissi,J. Rasmussen
Physics , 2003, DOI: 10.1088/0264-9381/20/23/002
Abstract: We study geometric engineering of four-dimensional N=1 gauge models from M-theory on a seven-dimensional manifold with G_2 holonomy. The manifold is constructed as a K3 fibration over a three-dimensional base space with ADE geometry. The resulting gauge theory is discussed in the realm of (p,q) webs. We discuss how the anomaly cancellation condition translates into a condition on the associated affine ADE Lie algebras.
Conformal Blocks for admissible representations in SL(2) current algebra
J. L. Petersen,J. Rasmussen,M. Yu
Physics , 1995, DOI: 10.1016/0550-3213(95)00499-8
Abstract: We show how to deal with screening charges involving fractional powers of free fields. This enables us to use the free field Wakimoto construction to obtain complete expressions for integral representations of conformal blocks for N-point functions on the sphere, also in the case of non-integrable representations, in particular for admissible representations. We verify several formal properties including the Knizhnik-Zamolodchikov equations. We discuss the fusion rules which result from our treatment, and compare with the literature.
Free field realization of SL(2) correlators for admissible representations, and hamiltonian reduction for correlators
J. L. Petersen,J. Rasmussen,M. Yu
Physics , 1995, DOI: 10.1016/0920-5632(96)00312-X
Abstract: Talk presented by J.L. Petersen at the 29th Symposium Ahrenshop, Buckow August 29-September 2, 1995. A presentation is given of the free field realization relevant to SL(2) WZW theories with a Hilbert space based on admissible representations. It is known that this implies the presence of two screening charges, one involving a fractional power of a free field. We develop the use of fractional calculus for treating in general such cases. We derive explicit integral representations of $N$-point conformal blocks. We show that they satisfy the Knizhnik-Zamolodchikov equations and we prove how they are related to minimal conformal blocks via a formulation of hamiltonian reduction advocated by Furlan, Ganchev, Paunov and Petkova.
Hamiltonian Reduction of $SL(2)$-theories at the Level of Correlators
J. L. Petersen,J. Rasmussen,M. Yu
Physics , 1995, DOI: 10.1016/0550-3213(95)00503-X
Abstract: Since the work of Bershadsky and Ooguri and Feigin and Frenkel it is well known that correlators of $SL(2)$ current algebra for admissible representations should reduce to correlators for conformal minimal models. A precise proposal for this relation has been given at the level of correlators: When $SL(2)$ primary fields are expressed as $\phi_j(z_n,x_n)$ with $x_n$ being a variable to keep track of the $SL(2)$ representation multiplet (possibly infinitely dimensional for admissible representations), then the minimal model correlator is supposed to be obtained simply by putting all $x_n=z_n$. Although strong support for this has been presented, to the best of our understanding a direct, simple proof seems to be missing so in this paper we present one based on the free field Wakimoto construction and our previous study of that in the present context. We further verify that the explicit $SL(2)$ correlators we have published in a recent preprint reduce in the above way, up to a constant which we also calculate. We further discuss the relation to more standard formulations of hamiltonian reduction.
Fusion, Crossing and Monodromy in Conformal Field Theory Based on $SL(2)$ Current Algebra with Fractional Level
J. L. Petersen,J. Rasmussen,M. Yu
Physics , 1996, DOI: 10.1016/S0550-3213(96)00506-8
Abstract: Based on our earlier work on free field realizations of conformal blocks for conformal field theories with $SL(2)$ current algebra and with fractional level and spins, we discuss in some detail the fusion rules which arise. By a careful analysis of the 4-point functions, we find that both the fusion rules previously found in the literature are realized in our formulation. Since this is somewhat contrary to our expectations in our first work based on 3-point functions, we reanalyse the 3-point functions and come to the same conclusion. We compare our results on 4-point conformal blocks in particular with a different realization of these found by O. Andreev, and we argue for the equivalence. We describe in detail how integration contours have to be chosen to obtain convenient bases for conformal blocks, both in his and in our own formulation. We then carry out the rather lengthy calculation to obtain the crossing matrix between s- and t-channel blocks, and we use that to determine the monodromy invariant 4-point greens functions. We use the monodromy coefficients to obtain the operator algebra coefficients for theories based on admissible representations.
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