25,647 research outputs found
Optimal life cycle portfolio choice with housing market cycles
During the last decades households in the U.S. have experienced that residential house prices move in a persistent manner, i.e. that returns are positively serially correlated. Since an owner-occupied home is usually the largest investment of a household it is important to understand how households act when they base their consumption and investment decisions on this experience. We show in a setting with housing market cycles and households who can decide whether they rent or own the home, that - besides the consumption and the precautionary savings motive - serial correlation in house prices generates a new speculative motive for homeownership. In particular, we show how good and bad housing market cycles affect homeownership rates, leverage, stock investments and consumption and can explain empirically observed household behavior during housing market boom and bust periods. Keywords: Asset Allocation , Portfolio Choice , Housing Market Cycles , Real Estate JEL Classification: G11, D9
Teaching Leadership from a Communication Perspective
Interest in leadership has intensified during the past decade. This heightened interest in leadership appears to be encouraging communication departments to offer leadership coursework. This article provides a model for a communication-based course in leadership. A sample syllabus, information on preferred teaching methods, and instructional resources are presented
Above-threshold ionization with highly-charged ions in super-strong laser fields: I. Coulomb-corrected strong field approximation
Aiming at the investigation of above-threshold ionization in super-strong
laser fields with highly charged ions, we develop a Coulomb-corrected strong
field approximation (SFA). The influence of the Coulomb potential of the atomic
core on the ionized electron dynamics in the continuum is taken into account
via the eikonal approximation, treating the Coulomb potential perturbatively in
the phase of the quasi-classical wave function of the continuum electron. In
this paper the formalism of the Coulomb-corrected SFA for the nonrelativistic
regime is discussed employing velocity and length gauge. Direct ionization of a
hydrogen-like system in a strong linearly polarized laser field is considered.
The relation of the results in the different gauges to the
Perelomov-Popov-Terent'ev imaginary-time method is discussed.Comment: 8 pages, 3 figure
Above-threshold ionization with highly-charged ions in super-strong laser fields: II. Relativistic Coulomb-corrected strong field approximation
We develop a relativistic Coulomb-corrected strong field approximation (SFA)
for the investigation of spin effects at above-threshold ionization in
relativistically strong laser fields with highly charged hydrogen-like ions.
The Coulomb-corrected SFA is based on the relativistic eikonal-Volkov wave
function describing the ionized electron laser-driven continuum dynamics
disturbed by the Coulomb field of the ionic core. The SFA in different
partitions of the total Hamiltonian is considered. The formalism is applied for
direct ionization of a hydrogen-like system in a strong linearly polarized
laser field. The differential and total ionization rates are calculated
analytically. The relativistic analogue of the Perelomov-Popov-Terent'ev
ionization rate is retrieved within the SFA technique. The physical relevance
of the SFA in different partitions is discussed.Comment: 11 pages, 4 figure
Ranking News-Quality Multimedia
News editors need to find the photos that best illustrate a news piece and
fulfill news-media quality standards, while being pressed to also find the most
recent photos of live events. Recently, it became common to use social-media
content in the context of news media for its unique value in terms of immediacy
and quality. Consequently, the amount of images to be considered and filtered
through is now too much to be handled by a person. To aid the news editor in
this process, we propose a framework designed to deliver high-quality,
news-press type photos to the user. The framework, composed of two parts, is
based on a ranking algorithm tuned to rank professional media highly and a
visual SPAM detection module designed to filter-out low-quality media. The core
ranking algorithm is leveraged by aesthetic, social and deep-learning semantic
features. Evaluation showed that the proposed framework is effective at finding
high-quality photos (true-positive rate) achieving a retrieval MAP of 64.5% and
a classification precision of 70%.Comment: To appear in ICMR'1
The Wigner time delay for laser induced tunnel-ionization via the electron propagator
Recent attoclock experiments using the attsecond angular streaking technique
enabled the measurement of the tunneling time delay during laser induced strong
field ionization. Theoretically the tunneling time delay is commonly modelled
by the Wigner time delay concept which is derived from the derivative of the
electron wave function phase with respect to energy. Here, we present an
alternative method for the calculation of the Wigner time delay by using the
fixed energy propagator. The developed formalism is applied to the
nonrelativistic as well as to the relativistic regime of the tunnel-ionization
process from a zero-range potential, where in the latter regime the propagator
can be given by means of the proper-time method.Comment: 5 pages, 4 figure
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