4,205 research outputs found
Particles adsorbed at various non-aqueous liquid-liquid interfaces
Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces. Nanocomposites of non-aqueous immiscible polymer blends containing inorganic particles at the interface are of great interest industrially and consequently more work has been devoted to them. By contrast, the behaviour of particles adsorbed at oil-oil interfaces in which both oils are immiscible and of low dielectric constant (ε < 3) is scarcely studied. Hydrophobic particles are required to stabilise these oil-oil emulsions due to their irreversible adsorption, high interfacial activity and elastic shell behaviour
Symmetry and quaternionic integrable systems
Given a hyperkahler manifold M, the hyperkahler structure defines a triple of
symplectic structures on M; with these, a triple of Hamiltonians defines a so
called hyperhamiltonian dynamical system on M. These systems are integrable
when can be mapped to a system of quaternionic oscillators. We discuss the
symmetry of integrable hyperhamiltonian systems, i.e. quaternionic oscillators;
and conversely how these symmetries characterize, at least in the Euclidean
case, integrable hyperhamiltonian systems.Comment: 26 page
Innovation and jobs: evidence from manufacturing firms
This paper is aimed at structurally assessing the employment effects of the innovative activities of firms. We estimate firm level displacement and compensation effects in a model in which the stock of knowledge capital raises firm relative efficiency through process innovations and firm demand through product innovations. Displacement is estimated from the elasticity of employment with respect to innovation in the (conditional or Hicksian) demand for labour. Compensation effects are estimated from a firm-specific demand relationship. We also assess the enlargement and weakening of these effects due to firm agents’ behaviour aimed at appropriating innovation rents. We find that the potential employment compensation effect of process innovations surpasses the displacement effect, both in the short and long run (when competitors react), and that product innovation doubles the expanding impact by unit of expenditure, but also that agents’ behaviour can seriously reduce these effects. The actual elasticity of employment to knowledge capital is estimated, however, not far from unity, while “passive” productivity growth is suggested to have null or negative employment effects.
Immigrants' Assimilation Process in a Segmented Labor Market
While much of the literature on immigrants' assimilation has focused on countries with a large tradition of receiving immigrants and with flexible labor markets, very little is known on how immigrants adjust to other types of host economies. With its severe dual labor market, and an unprecedented immigration boom, Spain presents a perfect natural experiment to analyze immigrations' assimilation process. Using data from the 2000 to 2008 Spanish Labor Force Survey, we find that immigrants are more occupationally mobile than natives, and that much of this greater flexibility is explained by immigrants' assimilation process soon after arrival. However, we find little evidence of convergence, especially among women and high skilled immigrants. This suggests that instead of integrating, immigrants are occupationally segregating, implying that there is both imperfect substitutability and underutilization of immigrants' human capital.immigrants' assimilation effects, cohort effects, occupational distributions and mobility, segmented labor markets
Commutative Toeplitz algebras and Gelfand theory
In this thesis we construct and study commutative Banach and C*-algebras
generated by Toeplitz operators on several function spaces.
We begin by introducing Banach algebras generated by Toeplitz operators with
quasi-radial and (II)-pseudo-homogeneous symbols (also called generalized pseudo-homogeneous symbols) acting on the weighted Bergman space over the unit ball of Cn. We characterize their maximal ideal space and Gelfand transform.
As an application we study the spectral invariance and semi-simplicity of these
algebras, and we provide an explicit description of their radical. Subsequently, we
present non-trivial examples of these results.
Afterwards, we carry over this construction to the Hardy space over the unit sphere of Cn and the Fock space with infinitely many variables defined over a separable Hilbert space H. In both cases we introduce analogous Banach algebras generated by Toeplitz operators with quasi-radial and (II)-pseudo-homogeneous symbols and characterize their maximal ideal space and Gelfand transform.
Moreover, we study C*-algebras generated by Toeplitz operators acting on the
Fock space on Cn whose symbols are invariant under the action by translations of
Lagrangian subgroups of Cn. We apply methods from Quantum Harmonic Analy-
sis to deduce the existence and commutativity of these algebras and subsequently
we describe their maximal ideal space and Gelfand transform.
Finally, we develop a framework on the Fock space with infinitely many
variables to perform Quantum Harmonic Analysis on it. We characterize the space
of Berezin transforms of trace-class operators and establish an L1 − T1 version of
the Correspondence Theorem inspired by the works of R. Fulsche and R. Werner
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