8,642 research outputs found
Merger Efficiency and Managerial Incentives
We consider a two-stage principal-agent model with limited liability in which a CEO is employed as agent to gather information about suitable merger targets and to manage the merged corporation in case of an acquisition. Our results show that the CEO systematically recommends targets with low synergies—even when targets with high synergies are available—to obtain high-powered incentives and, hence, a high personal income at the merger-management stage. We derive conditions under which shareholders prefer a self-commitment policy or a rent-reduction policy to deter the CEO from opportunistic recommendations
Anisotropic particles near surfaces: Self-propulsion and friction
We theoretically study the phenomenon of self-propulsion through Casimir
forces in thermal non-equilibrium. Using fluctuational electrodynamics, we
derive a formula for the self-propulsion force for an arbitrary small object in
two scenarios, i) for the object being isolated, and ii) for the object being
close to a planar surface. In the latter case, the self-propulsion force (i.e.,
the force parallel to the surface) increases with decreasing distance, i.e., it
couples to the near-field. We numerically calculate the lateral force acting on
a hot spheroid near a surface and show that it can be as large as the
gravitational force, thus being potentially measurable in fly-by experiments.
We close by linking our results to well-known relations of linear response
theory in fluctuational electrodynamics: Looking at the friction of the
anisotropic object for constant velocity, we identify a correction term that is
additional to the typically used approach.Comment: 13 pages, 8 figures (v2: References updated
Confined structures of least bending energy
In this paper we study a constrained minimization problem for the Willmore
functional. For prescribed surface area we consider smooth embeddings of the
sphere into the unit ball. We evaluate the dependence of the the minimal
Willmore energy of such surfaces on the prescribed surface area and prove
corresponding upper and lower bounds. Interesting features arise when the
prescribed surface area just exceeds the surface area of the unit sphere. We
show that (almost) minimizing surfaces cannot be a -small perturbation of
the sphere. Indeed they have to be nonconvex and there is a sharp increase in
Willmore energy with a square root rate with respect to the increase in surface
area.Comment: 27 pages, 3 figure
Government Debt in Europe
Haushaltsdefizit; Öffentliche Schulden; Europa
Heat radiation and transfer for point particles in arbitrary geometries
We study heat radiation and heat transfer for pointlike particles in a system
of other objects. Starting from exact many-body expressions found from
scattering theory and fluctuational electrodynamics, we find that transfer and
radiation for point particles are given in terms of the Green's function of the
system in the absence of the point particles. These general expressions contain
no approximation for the surrounding objects. As an application, we compute the
heat transfer between two point particles in the presence of a sphere of
arbitrary size and show that the transfer is enhanced by several orders of
magnitude through the presence of the sphere, depending on the materials.
Furthermore, we compute the heat emission of a point particle in front of a
planar mirror. Finally, we show that a particle placed inside a spherical
mirror cavity does not radiate energy.Comment: 14 pages, 9 figures (v2: Sec. IIIE was added; explanation of Eq. (29)
was added; sentence in Acknowledgments was added; Ref. [69] was added; minor
changes in text
Controlled nonuniformity in macroporous silicon pore growth
Photoelectrochemical etching of uniform prestructured silicon wafers in hydrofluoric acid containing solutions yields periodic structures that can be applied to two- and three-dimensional photonic crystals or microfluidics. Here we demonstrate experimentally macroporous silicon etching initiated by a nonuniform predefined lattice. For conveniently chosen parameters we observe a stable growth of pores whose geometrical appearance depends strongly on the spatially different nucleation conditions. Moreover, we show preliminary results on three-dimensionally shaped pores. This material can be used to realize hybrid photonic crystal structures and incorporate waveguides in three-dimensional photonic crystals
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