4,885 research outputs found
Declining interstitial transsudation in man
Results and methodology of experimentation dealing with declining interstitial transsudation are discussed. Concepts of the formation of interstitial fluids are in agreement with measurements of calf volume in normal young women, in horizontal recumbency or after horizontal immersion. The volume of the calf is reduced when the hydrostatic pressure of the blood column is diminished under the phlebostatic level and when the external pressure is increased by the hydrostatic pressure of a water bath
Finite size scaling of current fluctuations in the totally asymmetric exclusion process
We study the fluctuations of the current J(t) of the totally asymmetric
exclusion process with open boundaries. Using a density matrix renormalization
group approach, we calculate the cumulant generating function of the current.
This function can be interpreted as a free energy for an ensemble in which
histories are weighted by exp(-sJ(t)). We show that in this ensemble the model
has a first order space-time phase transition at s=0. We numerically determine
the finite size scaling of the cumulant generating function near this phase
transition, both in the non-equilibrium steady state and for large times.Comment: 18 pages, 11 figure
Commercial fire-retarded PET formulations - relationship between thermal degradation behaviour and fire-retardant action
Many types of fire-retardants are used in poly(ethylene terephthalate), PET, formulations, and two commercial fire retardants, Ukanol(TM) and Phosgard(TM), have been shown to improve significantly PET flame-retardancy when used as comonomers. Phosgard incorporates a phosphorus atom within the main chain whereas Ukanol incorporates a phosphorus atom as a pendent substituent. Despite their acknowledged effectiveness, the mode of action of these fire retardants remains unclear, and in this paper we present a comparison of the overall thermal degradation behaviour of PET and Ukanol and Phosgard fire retarded formulations. DSC and particularly TGA data show that both Ukanol and Phosgard have some stabilising influence on PET degradation, especially under oxidative conditions. TGA and pyrolysis experiments both clearly indicate that neither additive acts as a char promoter. Only the Phosgard formulation shows any release of volatile phosphorus species which could act in the gas phase. On the other hand, the most striking feature of the pyrolysis experiments is the macroscopic structure of the chars produced by the fire-retarded formulations, which hints at their fire-retardancy action - an open-cell charred foam was obtained upon charring at 400°C or 600°C. This foaming layer between the degrading melt and the flame would lower the amount of fuel available for combustion, and would also limit the feedback of heat to the condensed phase
Ab initio calculation of H + He charge transfer cross sections for plasma physics
The charge transfer in low energy (0.25 to 150 eV/amu) H() + He
collisions is investigated using a quasi-molecular approach for the as
well as the first two singlet states. The diabatic potential energy
curves of the HeH molecular ion are obtained from the adiabatic potential
energy curves and the non-adiabatic radial coupling matrix elements using a
two-by-two diabatization method, and a time-dependent wave-packet approach is
used to calculate the state-to-state cross sections. We find a strong
dependence of the charge transfer cross section in the principal and orbital
quantum numbers and of the initial or final state. We estimate the
effect of the non-adiabatic rotational couplings, which is found to be
important even at energies below 1 eV/amu. However, the effect is small on the
total cross sections at energies below 10 eV/amu. We observe that to calculate
charge transfer cross sections in a manifold, it is only necessary to
include states with , and we discuss the limitations of our
approach as the number of states increases.Comment: 14 pages, 10 figure
Critical parameters for the partial coalescence of a droplet
The partial coalescence of a droplet onto a planar liquid/liquid interface is
investigated experimentally by tuning the viscosities of both liquids. The
problem mainly depends on four dimensionless parameters: the Bond number
(gravity vs. surface tension), the Ohnesorge numbers (viscosity in both fluids
vs. surface tension), and the density relative difference. The ratio between
the daughter droplet size and the mother droplet size is investigated as a
function of these dimensionless numbers. Global quantities such as the
available surface energy of the droplet has been measured during the
coalescence. The capillary waves propagation and damping are studied in detail.
The relation between these waves and the partial coalescence is discussed.
Additional viscous mechanisms are proposed in order to explain the asymmetric
role played by both viscosities.Comment: 16 pages, 14 figures, submitted to Physical Review
A hermeneutic inquiry into user-created personas in different Namibian locales
Persona is a tool broadly used in technology design to support communicational interactions between designers and users. Different Persona types and methods have evolved mostly in the Global North, and been partially deployed in the Global South every so often in its original User-Centred Design methodology. We postulate persona conceptualizations are expected to differ across cultures. We demonstrate this with an exploratory-case study on user-created persona co-designed with four Namibian ethnic groups: ovaHerero, Ovambo, ovaHimba and Khoisan. We follow a hermeneutic inquiry approach to discern cultural nuances from diverse human conducts. Findings reveal diverse self-representations whereby for each ethnic group results emerge in unalike fashions, viewpoints, recounts and storylines. This paper ultimately argues User-Created Persona as a potentially valid approach for pursuing cross-cultural depictions of personas that communicate cultural features and user experiences paramount to designing acceptable and gratifying technologies in dissimilar locales
Studies on the infestation by Eutypa lata of grapevine spring wounds
Natural infestation and controlled inoculations of grapevine (mostly on the cultivar 'Cabernet Sauvignon'), were conducted in Bordeaux vineyards from 1998 to 2004 to evaluate the susceptibility to E. lata of spring wounds caused by the removal of either excess buds or excess suckers. Natural infestation was assessed across a range of sites to quantify and compare the relative risk of spring and winter pruning wounds to contamination by E. lata. Infestation caused by inoculation of wounds was examined in one site using either 100 (lower inoculum density) or 1000 (higher inoculum density) ascospores per wound. Wounds were allowed to incubate at the wound site for either two weeks or one year before isolations. For natural colonisation of wounds, a low level of infestation of spring wounds (average 2.1 %) was detected, less than those for winter pruning wounds (average 13 %). A similar trend was detected in trials involving inoculation of spring and winter pruning wounds despite infestation with identical levels of inoculum. No difference in recovery rates of E. lata was found between spring wounds caused by the removal of buds or suckers. A longer incubation period significantly increased the mean efficiency of recovery. We conclude that spring wounds may pose a significant risk to the colonisation of grapevine by the pathogen E. lata, albeit less than that of winter pruning wounds, suggesting a secondary role in the epidemiology of Eutypa dieback.
On sl(2)-equivariant quantizations
By computing certain cohomology of Vect(M) of smooth vector fields we prove
that on 1-dimensional manifolds M there is no quantization map intertwining the
action of non-projective embeddings of the Lie algebra sl(2) into the Lie
algebra Vect(M). Contrariwise, for projective embeddings sl(2)-equivariant
quantization exists.Comment: 09 pages, LaTeX2e, no figures; to appear in Journal of Nonlinear
Mathematical Physic
A numerical approach to large deviations in continuous-time
We present an algorithm to evaluate the large deviation functions associated
to history-dependent observables. Instead of relying on a time discretisation
procedure to approximate the dynamics, we provide a direct continuous-time
algorithm, valuable for systems with multiple time scales, thus extending the
work of Giardin\`a, Kurchan and Peliti (PRL 96, 120603 (2006)).
The procedure is supplemented with a thermodynamic-integration scheme, which
improves its efficiency. We also show how the method can be used to probe large
deviation functions in systems with a dynamical phase transition -- revealed in
our context through the appearance of a non-analyticity in the large deviation
functions.Comment: Submitted to J. Stat. Mec
First-order dynamical phase transition in models of glasses: an approach based on ensembles of histories
We investigate the dynamics of kinetically constrained models of glass
formers by analysing the statistics of trajectories of the dynamics, or
histories, using large deviation function methods. We show that, in general,
these models exhibit a first-order dynamical transition between active and
inactive dynamical phases. We argue that the dynamical heterogeneities
displayed by these systems are a manifestation of dynamical first-order phase
coexistence. In particular, we calculate dynamical large deviation functions,
both analytically and numerically, for the Fredrickson-Andersen model, the East
model, and constrained lattice gas models. We also show how large deviation
functions can be obtained from a Landau-like theory for dynamical fluctuations.
We discuss possibilities for similar dynamical phase-coexistence behaviour in
other systems with heterogeneous dynamics.Comment: 29 pages, 7 figs, final versio
- …