861 research outputs found
Sectors and Strategies of Global Communications Regulation
As the global communication network matures, the systems and procedures for regulating the growing network and its use are being challenged. The general proliferation of services or the specific demand for electronic transactions require guidance and control which the market alone cannot supply. Meanwhile, traditional regulatory regimes remain far from global or coherent. This article distinguishes between coordination and regulation to clarify areas where government intervention is unnecessary and where indispensable. It explores the current patchwork of regulatory approaches, reviews different regulatory areas and strategies, identifies trends, and highlights problem areas particular to electronic commerce and third party protection
Exact Self-consistent Particle-like Solutions to the Equations of Nonlinear Scalar Electrodynamics in General Relativity
Exact self-consistent particle-like solutions with spherical and/or
cylindrical symmetry to the equations governing the interacting system of
scalar, electromagnetic and gravitational fields have been obtained. As a
particular case it is shown that the equations of motion admit a special kind
of solutions with sharp boundary known as droplets. For these solutions, the
physical fields vanish and the space-time is flat outside of the critical
sphere or cylinder. Therefore, the mass and the electric charge of these
configurations are zero.Comment: 17 pages, Submitted to the International Journal of Theoretical
Physic
Age- and Gender-Specific Normative Data of Grip and Pinch Strength in a Healthy Adult Swiss Population
Assessment of hand strength is used in a wide range of clinical settings especially during treatment of diseases affecting the function of the hand. This investigation aimed to determine age- and gender-specific reference values for grip and pinch strength in a normal Swiss population with special regard to old and very old subjects as well as to different levels of occupational demand. Hand strength data were collected using a Jamar dynamometer and a pinch gauge with standard testing position, protocol and instructions. Analysis of the data from 1023 tested subjects between 18 and 96 years revealed a curvilinear relationship of grip and pinch strength to age, a correlation to height, weight and significant differences between occupational groups. Hand strength values differed significantly from those of other populations, confirming the thesis that applying normative data internationally is questionable. Age- and gender-specific reference values for grip and pinch strength are presented
The morphological transformation of ram pressure stripped galaxies: a pathway from late to early galaxy types
We investigate how the ageing of stellar populations can drive a
morphological transformation in galaxies whose star formation (SF) activity has
been quenched on short timescales, like in cluster galaxies subject to ram
pressure stripping from the intracluster medium. For this purpose, we use a
sample of 91 galaxies with MUSE data from the GASP program and of their
spatially resolved SF history derived with the spectral modelling software
SINOPSIS. We simulate the future continuation of the SF activities by exploring
two quenching scenarios: an instantaneous truncation of the SF across the whole
disc, and an outside-in quenching with typical stripping timescales of 0.5 Gyr
and 1 Gyr. For each scenario we produce mock MUSE spectroscopic datacubes and
optical images for our galaxies during their evolution, and classify their
morphology using a new diagnostic tool, calibrated on cluster galaxies from the
OmegaWINGS Survey. We find that, in all scenarios considered, the initial
galaxy population dominated by blue-cloud spirals (90%) evolves into a mixed
population mostly composed by red-sequence spirals (50-55%) and lenticulars
(~40%). The morphology transformation is completed after just 1.5-3.5 Gyr,
proceeding faster in more efficient quenching scenarios. Our results indicate
that, even without accounting for dynamical processes, SF quenching caused by
the harsh environment of a cluster can significantly affect the morphology of
the infalling galaxy population on timescales of a few Gyr.Comment: 19 pages, 11 figures, accepted for publication in MNRA
Movement of Xylosandrus germanus (Coleoptera: Curculionidae) in Ornamental Nurseries and Surrounding Habitats
Some exotic ambrosia beetles are damaging pests in ornamental nurseries. Xylosandrus germanus (Blandford) is the most problematic ambrosia beetle in Ohio nurseries. Movement of X. germanus in nurseries has not been characterized, and knowledge is lacking on whether infestations originate from within nurseries or surrounding habitats. Flight activity of X. germanus was monitored in nurseries and adjacent wooded areas to determine the source of beetles infesting nurseries, and characterize their movement within nurseries. Ethanol-baited bottle traps were positioned within wooded areas adjacent to commercial nurseries and within nurseries at various distances from the nursery woodlot interface. Flight activity of overwintered X. germanus occurred in wooded areas adjacent to nurseries before occurrence within nurseries. There was a direct relationship between degree-days and the distance from woodlots when X. germanus were first found in traps in spring, with earlier captures closest to wooded areas and latest ones furthest away into the nursery. X. germanus appeared to move into nurseries from adjacent wooded areas, with numbers trapped within nurseries decreasing with distance away from wooded areas. Trees in the interior of nurseries would appear to be subjected to less attack pressure than trees near the nursery border. Intercepting beetles as they move into nurseries might be an effective strategy to reduce attack pressure on valuable trees
Slow-light enhanced light-matter interactions with applications to gas sensing
Optical gas detection in microsystems is limited by the short micron scale
optical path length available. Recently, the concept of slow-light enhanced
absorption has been proposed as a route to compensate for the short path length
in miniaturized absorption cells. We extend the previous perturbation theory to
the case of a Bragg stack infiltrated by a spectrally strongly dispersive gas
with a narrow and distinct absorption peak. We show that considerable signal
enhancement is possible. As an example, we consider a Bragg stack consisting of
PMMA infiltrated by O2. Here, the required optical path length for visible to
near-infrared detection (~760 nm) can be reduced by at least a factor of 10^2,
making a path length of 1 mm feasible. By using this technique, optical gas
detection can potentially be made possible in microsystems
CP-Violation in Bosonic Sector of SM with two Higgs Doublets
We investigate CP-violation effects in the bosonic sector of the Standard
Model (SM) with two Higgs doublets. First we calculate the mass eigenstates of
the physical neutral Higgses for small but nonzero CP-violation parameter
, and then a ``forward-backward'' asymmetry for the
decay that would be a signal of CP-violation. Although the
effects are in general small (), turns out to be a rather clean signal of
CP-violation, since neither the CP-conserving final state interactions nor the
direct production background events contribute to . The process is
a counterexample to the widespread belief that CP-violation processes must
involve fermions. The CKM-type CP-violation effects that could in principle
also contribute to are negligible. The nonzero
could possibly be detected at some later stage in future colliders such as LHC
or SSC.Comment: 11 pages (standard LaTeX), 3 figures (available from the author),
DO-TH 93-1
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