6,909 research outputs found
Viscous fingering in miscible, immiscible and reactive fluids
With the Lattice Boltzmann method (using the BGK approximation) we
investigate the dynamics of Hele-Shaw flow under conditions corresponding to
various experimental systems. We discuss the onset of the instability
(dispersion relation), the static properties (characterization of the
interface) and the dynamic properties (growth of the mixing zone) of simulated
Hele-Shaw systems. We examine the role of reactive processes (between the two
fluids) and we show that they have a sharpening effect on the interface similar
to the effect of surface tension.Comment: 6 pages with 2 figure, to be published in J.Mod.Phys
Nonextensive diffusion as nonlinear response
The porous media equation has been proposed as a phenomenological
``non-extensive'' generalization of classical diffusion. Here, we show that a
very similar equation can be derived, in a systematic manner, for a classical
fluid by assuming nonlinear response, i.e. that the diffusive flux depends on
gradients of a power of the concentration. The present equation distinguishes
from the porous media equation in that it describes \emph{% generalized
classical} diffusion, i.e. with scaling, but with a generalized
Einstein relation, and with power-law probability distributions typical of
nonextensive statistical mechanics
Subglacial drainage processes at a High Arctic polythermal valley glacier
Peer reviewedPublisher PD
An Econometric Analysis of the NW/KLM Corporate Alliance
This thesis investigates whether a corporate alliance between international air carriers is beneficial, considering the changes in the global air transport system. Dividing the research method into three phases, the author first lists and identifies the recent changes in world air transport trends. Then, the author defines the different types of alliances and studies the advantages and disadvantages of these corporate alliances. Finally, a multiple regression analysis is performed using the KLM/Northwest Airlines alliance as a case analysis
Bacterial exchange in household washing machines
Household washing machines (WMs) launder soiled clothes and textiles, but do not sterilize them. We investigated the microbial exchange occurring in five household WMs. Samples from a new cotton T-shirt were laundered together with a normal laundry load. Analyses were performed on the influent water and the ingoing cotton samples, as well as the greywater and the washed cotton samples. The number of living bacteria was generally not lower in the WM effluent water as compared to the influent water. The laundering process caused a microbial exchange of influent water bacteria, skin-, and clothes related bacteria and biofilm-related bacteria in the WM. A variety of biofilm-producing bacteria were enriched in the effluent after laundering, although their presence in the cotton sample was low. Nearly all bacterial genera detected on the initial cotton sample were still present in the washed cotton samples. A selection for typical skin- and clothes related microbial species occurred in the cotton samples after laundering. Accordingly, malodour-causing microbial species might be further distributed to other clothes. The bacteria on the ingoing textiles contributed for a large part to the microbiome found in the textiles after laundering
Screening of heterogeneous surfaces: charge renormalization of Janus particles
Nonlinear ionic screening theory for heterogeneously charged spheres is
developed in terms of a mode-decomposition of the surface charge. A far-field
analysis of the resulting electrostatic potential leads to a natural
generalization of charge renormalization from purely monopolar to dipolar,
quadropolar, etc., including mode-couplings. Our novel scheme is generally
applicable to large classes of surface heterogeneities, and is explicitly
applied here to Janus spheres with differently charged upper and lower
hemispheres, revealing strong renormalization effects for all multipoles.Comment: 2 figure
Association Between Smoking and Tuberculosis Infection: A Population Survey in a High Tuberculosis Incidence Area
Associations between smoking and tuberculosis disease including death from tuberculosis have been reported, but there are few reports on the influence of smoking on the risk of developing Mycobacterium tuberculosis infection. The aim of this study was to determine the association between smoking and M tuberculosis infection. In a cross sectional population survey, data on smoking and tuberculin skin test (TST) results of 2401 adults aged >15 years were compared. A total of 1832 (76%) subjects had a positive TST (>10 mm induration). Of 1309 current smokers or ex-smokers, 1070 (82%) had a positive TST. This was significantly higher than for never smokers (unadjusted OR 1.99, 95% confidence interval (CI) 1.62 to 2.45). A positive relationship with pack-years was observed, with those smoking more than 15 pack-years having the highest risk (adjusted OR 1.90,95% CI 1.28 to 2.81). Smoking may increase the risk of M tuberculosis infection.\u
De Natuurschoonwet: Borger van Nederlands natuurschoon?
De Natuurschoonwet (NSW) biedt voor landgoederen in Nederland diverse fiscale voordelen. De NSW stelt geen eisen aan de kwaliteit van het natuurschoon, wel aan de omvang van het landgoed (namelijk minstens 5 ha groot). Wat is de invloed van deze wet op landgoederen. Dat is nagegaan in een studentenonderzoek (Schuurman) door drie landgoederen onder de loep te nemen en tevens bij 23 landgoederen de toekomstmogelijkheden na te gaan, en wel in Overijssel en Gelderlan
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