229 research outputs found
Transparent tiles of silica aerogels for high-energy physics
Silica aerogels are important to be used as photon radiators in Cherenkov
counters for high-energy-physics experiments because of their optical
transparency and intermediate refractive indices between those of gases and
liquids or solids. Cherenkov counters that employ silica aerogels as radiators
and photodetectors are often used to identify subatomic charged particles
(e.g., electrons, protons, and pions) with momenta on the order of sub-GeV/
to GeV/; they are also used to measure particle velocities in
accelerator-based particle- and nuclear-physics experiments and in space- and
balloon-borne experiments in the field of cosmic-ray physics. Recent studies
have demonstrated that it is important for the design of Cherenkov counters
that the transparent silica-aerogel tiles comprise solid material with recently
improved transparency and a refractive index that can be controlled between
1.003 and 1.26 by varying the bulk density in the range of 0.011.0 g/cm.
Additionally, a technique for fabricating large-area silica-aerogel tiles
without cracking has been developed. In this chapter, we describe advances in
the technologies for producing silica aerogels with high optical performances
to be used in scientific instruments. We further discuss the principles
underlying the operation of detectors based on the Cherenkov effect. We also
review applications of silica aerogels in specific high-energy-physics
experiments.Comment: Contributed chapter submitted to Springer Handbook of Aerogels (2nd
ed.
Parallel Imports, Drag Price Control and Pharmaceutical Innovation
This paper examines how parallel importation influences pharmaceutical innovation and the welfare of the economy, when crossnational drug price differentials occur not only because of demand elasticity based factors, but also governmental drug price control based factors. By explicitly considering the governmental drug price control baaed factors, this paper shows that parallel importation may enhance pharmaceutical innovation, when the bargaining power of a foreign government is strong and the price elasticity of demand in the foreign market is small. We also show that the increase in R&D induced by parallel imports may even increase the consumer surplus of a country with high demand elasticities and which could face relatively low drug prices, if parallel imports were not allowed.Parallel Imports, Pharmaceutical Innovation, Drug Price Control
Recent progress in silica aerogel Cherenkov radiator
In this paper, we present recent progress in the development of hydrophobic
silica aerogel as a Cherenkov radiator. In addition to the conventional method,
the recently developed pin-drying method for producing high-refractive-index
aerogels with high transparency was studied in detail. Optical qualities and
large tile handling for crack-free aerogels were investigated. Sufficient
photons were detected from high-performance aerogels in a beam test.Comment: Proceedings of 2nd International Conference on Technology and
Instrumentation in Particle Physics (TIPP 2011), to be published in Physics
Procedia, 8 pages, 7 figure
Larval cells become imaginal cells under the control of homothorax prior to metamorphosis in the Drosophila tracheal system
AbstractIn Drosophila melanogaster, one of the most derived species among holometabolous insects, undifferentiated imaginal cells that are set-aside during larval development are thought to proliferate and replace terminally differentiated larval cells to constitute adult structures. Essentially all tissues that undergo extensive proliferation and drastic morphological changes during metamorphosis are thought to derive from these imaginal cells and not from differentiated larval cells. The results of studies on metamorphosis of the Drosophila tracheal system suggested that large larval tracheal cells that are thought to be terminally differentiated may be eliminated via apoptosis and rapidly replaced by small imaginal cells that go on to form the adult tracheal system. However, the origin of the small imaginal tracheal cells has not been clear. Here, we show that large larval cells in tracheal metamere 2 (Tr2) divide and produce small imaginal cells prior to metamorphosis. In the absence of homothorax gene activity, larval cells in Tr2 become non-proliferative and small imaginal cells are not produced, indicating that homothorax is necessary for proliferation of Tr2 larval cells. These unexpected results suggest that larval cells can become imaginal cells and directly contribute to the adult tissue in the Drosophila tracheal system. During metamorphosis of less derived species of holometabolous insects, adult structures are known to be formed via cells constituting larval structures. Thus, the Drosophila tracheal system may utilize ancestral mode of metamorphosis
Licensing of complementary technologies and enforcement of intellectual property rights
In this paper, we examine the effect of enforcement of IPR on the equilibrium outcome and welfare through unilateral and cross licensing decisions between duopolistic firms with patents of two complementary technologies. We find the conditions on both the imitation cost of the infringer and probability of the accuser firm winning the lawsuit under that a unilateral licensing / a cross licensing may be contracted between them, and efficient social surplus of duopoly realizes
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