947 research outputs found
Ranges of operators and Derivatives
[EN] We show a unified method of proving the existence of C(1)-Frechet smooth and Lipschitz mappings which are surjective or whose range of the derivative contains the whole dual unit ball. As an application, under Martin's Maximum axiom, we obtain a complete result for those spaces with density character omega(1). (C) 2009 Elsevier Inc. All rights reserved.Research supported by Project MTM2008-05396 and the Universidad Politecnica de Valencia.
Research supported by the grants A100190502, IAA 100190801 and Inst. Research Plan AV0Z10190503.
Research supported by Project MTM2008-03211 and the Universidad Politecnica de Valencia.Guirao Sánchez, AJ.; Hájek, P.; Montesinos Santalucia, V. (2010). Ranges of operators and Derivatives. Journal of Mathematical Analysis and Applications. 367(1):29-33. https://doi.org/10.1016/j.jmaa.2009.12.010S2933367
Phase separating binary fluids under oscillatory shear
We apply lattice Boltzmann methods to study the segregation of binary fluid
mixtures under oscillatory shear flow in two dimensions. The algorithm allows
to simulate systems whose dynamics is described by the Navier-Stokes and the
convection-diffusion equations. The interplay between several time scales
produces a rich and complex phenomenology. We investigate the effects of
different oscillation frequencies and viscosities on the morphology of the
phase separating domains. We find that at high frequencies the evolution is
almost isotropic with growth exponents 2/3 and 1/3 in the inertial (low
viscosity) and diffusive (high viscosity) regimes, respectively. When the
period of the applied shear flow becomes of the same order of the relaxation
time of the shear velocity profile, anisotropic effects are clearly
observable. In correspondence with non-linear patterns for the velocity
profiles, we find configurations where lamellar order close to the walls
coexists with isotropic domains in the middle of the system. For particular
values of frequency and viscosity it can also happen that the convective
effects induced by the oscillations cause an interruption or a slowing of the
segregation process, as found in some experiments. Finally, at very low
frequencies, the morphology of domains is characterized by lamellar order
everywhere in the system resembling what happens in the case with steady shear.Comment: 1 table and 12 figures in .gif forma
Polynomial-Time Amoeba Neighborhood Membership and Faster Localized Solving
We derive efficient algorithms for coarse approximation of algebraic
hypersurfaces, useful for estimating the distance between an input polynomial
zero set and a given query point. Our methods work best on sparse polynomials
of high degree (in any number of variables) but are nevertheless completely
general. The underlying ideas, which we take the time to describe in an
elementary way, come from tropical geometry. We thus reduce a hard algebraic
problem to high-precision linear optimization, proving new upper and lower
complexity estimates along the way.Comment: 15 pages, 9 figures. Submitted to a conference proceeding
New light for time series: international collaboration in ship-based ecosystem monitoring.
Ship-based biogeochemical and ecological time series are one of the most valuable tools to
characterize and quantify ocean ecosystems. These programs continuously provided major
breakthroughs in understanding ecosystem variability, allow quantification of the ocean carbon cycle,
and help understand the processes that link biodiversity, food webs, and changes in services that
benefit human societies. A quantum jump in regional and global ocean ecosystem science can be
gained by aggregating observations from individual time series that are distributed across different
oceans and which are managed by different countries. The collective value of these data is greater
than that provided by each time series individually. However, maintaining time series requires a
commitment by the science community and sponsor agencies.. Based on the success of existing
initiatives, e.g. ICES and SCOR working groups, IOC-UNESCO launched the International Group for
Marine Ecological Time Series (IGMETS, http://igmets.net) to promote collaborations across different
individual projects, and jointly look at holistic changes within different ocean regions. The effort
explores the reasons and connections for changes in phytoplankton and zooplankton at a global level
and identifies locations where particularly large changes may be ocurring. This compilation will
facilitate better coordination, communication, and data intercomparability among time series.IEO (RADIALES) IOC-UNESC
Complete Break Up of Ortho Positronium (Ps)- Hydrogenic ion System
The dynamics of the complete breakup process in an Ortho Ps - He+ system
including electron loss to the continuum (ELC) is studied where both the
projectile and the target get ionized. The process is essentially a four body
problem and the present model takes account of the two centre effect on the
electron ejected from the Ps atom which is crucial for a proper description of
the ELC phenomena. The calculations are performed in the framework of Coulomb
Distorted Eikonal Approximation. The exchange effect between the target and the
projectile electron is taken into account in a consistent manner. The proper
asymptotic 3-body boundary condition for this ionization process is also
satisfied in the present model. A distinct broad ELC peak is noted in the fully
differential cross sections (5DCS) for the Ps electron corroborating
qualitatively the experiment for the Ps - He system. Both the dynamics of the
ELC from the Ps and the ejected electron from the target He+ in the FDCS are
studied using coplanar geometry. Interesting features are noted in the FDCS for
both the electrons belonging to the target and the projectile.Comment: 14 pages,7 figure
The interaction between people, information and innovation: information literacy to underpin innovative work behaviour in a Finnish organisation
Workplace learning and employee-led innovation are related. For example, mistakes made when learning may spur innovation. Investigated in this paper is the role of information literacy in the learning of innovative work behaviour in the workplace, and the associated information behaviours that allow for innovative work behaviour to develop. Thus interactions between people, information and innovation are a main focus. The findings derive from analysis of data generated in twelve semi-structured interviews conducted within a Finnish organisation. Employee perceptions on the role of information in the workplace, and its role in supporting the learning of innovative work behaviour, are explored. The analysis reveals that: (1) information literacy skills serve as a prerequisite for workplace learning; (2) information behaviours support the learning of innovative work be-haviour and; (3) a variety of information sources support employees as they learn to behave innovatively
Ordering of the lamellar phase under a shear flow
The dynamics of a system quenched into a state with lamellar order and
subject to an uniform shear flow is solved in the large-N limit. The
description is based on the Brazovskii free-energy and the evolution follows a
convection-diffusion equation. Lamellae order preferentially with the normal
along the vorticity direction. Typical lengths grow as (with
logarithmic corrections) in the flow direction and logarithmically in the shear
direction. Dynamical scaling holds in the two-dimensional case while it is
violated in D=3
The nature of slow dynamics in a minimal model of frustration-limited domains
We present simulation results for the dynamics of a schematic model based on
the frustration-limited domain picture of glass-forming liquids. These results
are compared with approximate theoretical predictions analogous to those
commonly used for supercooled liquid dynamics. Although model relaxation times
increase by several orders of magnitude in a non-Arrhenius manner as a
microphase separation transition is approached, the slow relaxation is in many
ways dissimilar to that of a liquid. In particular, structural relaxation is
nearly exponential in time at each wave vector, indicating that the mode
coupling effects dominating liquid relaxation are comparatively weak within
this model. Relaxation properties of the model are instead well reproduced by
the simplest dynamical extension of a static Hartree approximation. This
approach is qualitatively accurate even for temperatures at which the mode
coupling approximation predicts loss of ergodicity. These results suggest that
the thermodynamically disordered phase of such a minimal model poorly
caricatures the slow dynamics of a liquid near its glass transition
Computer simulation study of the nematic–vapour interface in the Gay–Berne model
We present computer simulations of the vapour–nematic interface of the Gay–Berne model. We considered situations which correspond to either prolate or oblate molecules. We determine the anchoring of the nematic phase and correlate it with the intermolecular potential parameters. On the other hand, we evaluate the surface tension associated to this interface. We find a corresponding states law for the surface tension dependence on the temperature, valid for both prolate and oblate molecules.FundaciĂłn Portuguesa para la Ciencia y la TecnologĂa EXCL / FIS-NAN / 0083/2012Ministerio de EconomĂa y Competitividad FIS2012-32455Junta de AndalucĂa P09-FQM-493
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