9,523 research outputs found
The Escape-Infringement Effect of Blocking Patents on Innovation and Economic Growth
This study develops a Schumpeterian growth model to analyze the effects of different patent instruments on innovation. We first analyze patent breadth that captures the traditional positive effect of patent rights on innovation. Then, we consider a profit-division rule between entrants and incumbents. Given the division of profit, increasing the share of profit assigned to incumbents reduces entrants' incentives for innovation. This aspect of blocking patents captures the recently proposed negative effect of patent rights on innovation. Finally, blocking patents generate a non-monotonic effect on innovation when the step size of innovation is endogenous due to a novel escape-infringement effect. Calibrating the model to aggregate data, we find that a marginal increase in the blocking effect of patent protection is likely to raise economic growth.economic growth; innovation; intellectual property rights
Magnification relations of quad lenses and applications on Einstein crosses
In this work, we mainly study the magnification relations of quad lens models
for cusp, fold and cross configurations. By dividing and ray-tracing in
different image regions, we numerically derive the positions and magnifications
of the four images for a point source lying inside of the astroid caustic.
Then, based on the magnifications, we calculate the signed cusp and fold
relations for the singular isothermal elliptical lenses. The signed fold
relation map has positive and negative regions, and the positive region is
usually larger than the negative region as has been confirmed before. It can
also explain that for many observed fold image pairs, the fluxes of the Fermat
minimum images are apt to be larger than those of the saddle images. We define
a new quantity cross relation which describes the magnification discrepancy
between two minimum images and two saddle images. Distance ratio is also
defined as the ratio of the distance of two saddle images to that of two
minimum images. We calculate the cross relations and distance ratios for nine
observed Einstein crosses. In theory, for most of the quad lens models, the
cross relations decrease as the distance ratios increase. In observation, the
cross relations of the nine samples do not agree with the quad lens models very
well, nevertheless, the cross relations of the nine samples do not give obvious
evidence for anomalous flux ratio as the cusp and fold types do. Then, we
discuss several reasons for the disagreement, and expect good consistencies for
more precise observations and better lens models in the future.Comment: 12 pages, 11 figures, accepted for publication in MNRA
Photoemission Spectroscopy of Magnetic and Non-magnetic Impurities on the Surface of the BiSe Topological Insulator
Dirac-like surface states on surfaces of topological insulators have a chiral
spin structure that suppresses back-scattering and protects the coherence of
these states in the presence of non-magnetic scatterers. In contrast, magnetic
scatterers should open the back- scattering channel via the spin-flip processes
and degrade the state's coherence. We present angle-resolved photoemission
spectroscopy studies of the electronic structure and the scattering rates upon
adsorption of various magnetic and non-magnetic impurities on the surface of
BiSe, a model topological insulator. We reveal a remarkable
insensitivity of the topological surface state to both non-magnetic and
magnetic impurities in the low impurity concentration regime. Scattering
channels open up with the emergence of hexagonal warping in the high-doping
regime, irrespective of the impurity's magnetic moment.Comment: 5 pages, 4 figure
Order batching and picking in a synchronized zone order picking system
Order picking has been considered as one of the most critical operations in warehouse. In this study, we propose an analytical approximation model based on probability and queueing network theory to analyze order batching and picking area zoning on the mean order throughput time in a synchronized zone picker-to-part order picking system. The resulting model can be easily applied in the design and selection process of order picking systems. © 2011 IEEE.published_or_final_versionThe IEEE International Conference on Industrial Engineering and Engineering Management (IEEM 2011), Singapore, 6-9 December 2011. In Proceedings of the IEEE IEEM, 2011, p. 156-16
Raman and IR spectra of water under graphene nanoconfinement at ambient and extreme pressure-temperature conditions: a first-principles study
The nanoconfinement of water can result in dramatic differences in its
physical and chemical properties compared to bulk water. However, a detailed
molecular-level understanding of these properties is still lacking. Vibrational
spectroscopy, such as Raman and infrared, is a popular experimental tool for
studying the structure and dynamics of water, and is often complemented by
atomistic simulations to interpret experimental spectra, but there have been
few theoretical spectroscopy studies of nanoconfined water using
first-principles methods at ambient conditions, let alone under extreme
pressure-temperature conditions. Here, we computed the Raman and IR spectra of
water nanoconfined by graphene at ambient and extreme pressure-temperature
conditions using ab intio simulations. Our results revealed alterations in the
Raman stretching and low-frequency bands due to the graphene confinement. We
also found spectroscopic evidence indicating that nanoconfinement considerably
changes the tetrahedral hydrogen bond network, which is typically found in bulk
water. Furthermore, we observed an unusual bending band in the Raman spectrum
at ~10 GPa and 1000 K, which is attributed to the unique molecular structure of
confined ionic water. Additionally, we found that at ~20 GPa and 1000 K,
confined water transformed into a superionic fluid, making it challenging to
identify the IR stretching band. Finally, we computed the ionic conductivity of
confined water in the ionic and superionic phases. Our results highlight the
efficacy of Raman and IR spectroscopy in studying the structure and dynamics of
nanoconfined water in a large pressure-temperature range. Our predicted Raman
and IR spectra can serve as a valuable guide for future experiments
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