Low-distortion slow light using two absorption resonances

We consider group delay and broadening using two strongly absorbing and widely spaced resonances. We derive relations which show that very large pulse bandwidths coupled with large group delays and small broadening can be achieved. Unlike single resonance systems, the dispersive broadening dominates the absorptive broadening which leads to a dramatic increase in the possible group delay. We show that the double resonance systems are excellent candidates for realizing all-optical delay lines. We report on an experiment which achieved up to 50 pulse delays with 40% broadening.Comment: 4 pages 4 figure

Hands-On Universe: A Global Program for Education and Public Outreach in Astronomy

Hands-On Universe (HOU) is an educational program that enables students to investigate the Universe while applying tools and concepts from science, math, and technology. Using the Internet, HOU participants around the world request observations from an automated telescope, download images from a large image archive, and analyze them with the aid of user-friendly image processing software. This program is developing now in many countries, including the USA, France, Germany, Sweden, Japan, Australia, and others. A network of telescopes has been established among these countries, many of them remotely operated, as shown in the accompanying demo. Using this feature, students in the classroom are able to make night observations during the day, using a telescope placed in another country. An archive of images taken on large telescopes is also accessible, as well as resources for teachers. Students are also dealing with real research projects, e.g. the search for asteroids, which resulted in the discovery of a Kuiper Belt object by high-school students. Not only Hands-On Universe gives the general public an access to professional astronomy, but it is also a more general tool to demonstrate the use of a complex automated system, the techniques of data processing and automation. Last but not least, through the use of telescopes located in many countries over the globe, a form of powerful and genuine cooperation between teachers and children from various countries is promoted, with a clear educational goal.Comment: 4 pages, 1 figure, to appear in the proceedings of the ADASS X conference, Boston, October 2000, ASP conf. pro

Time-dependent wave-packet approach for fusion reactions of halo nuclei

The fusion reaction of a halo nucleus 11Be on 208Pb is described by a three-body direct reaction model. A time-dependent wave packet approach is applied to a three-body reaction problem. The wave packet approach enables us to obtain scattering solutions without considering the three-body scattering boundary conditions. The time evolution of the wave packet also helps us to obtain intuitive understanding of the reaction dynamics. The calculations indicate a decrease of the fusion probability by the presence of the halo neutron.Comment: 7 pages, 3 figures, use espcrc1.sty, Talk at the International Symposium on "Physics of Unstable Nuclei (ISPUN02)", Halong Bay, Vietnam, November 20-25, 200

Kinematic Orbits and the Structure of the Internal Space for Systems of Five or More Bodies

The internal space for a molecule, atom, or other n-body system can be conveniently parameterised by 3n-9 kinematic angles and three kinematic invariants. For a fixed set of kinematic invariants, the kinematic angles parameterise a subspace, called a kinematic orbit, of the n-body internal space. Building on an earlier analysis of the three- and four-body problems, we derive the form of these kinematic orbits (that is, their topology) for the general n-body problem. The case n=5 is studied in detail, along with the previously studied cases n=3,4.Comment: 38 pages, submitted to J. Phys.

Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor

We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns (group index of approximately 200) with little pulse distortion. The delay is made tunable with a fast reconfiguration time (hundreds of ns) by optically pumping out of the atomic ground states.Comment: 4 pages, 6 figure

GEM Operation in Negative Ion Drift Gas Mixtures

The first operation of GEM gas gain elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single-stage GEMs in carbon disulfide vapor at low pressure, and in mixtures of carbon disulfide with Argon and Helium, some near 1 bar total pressure.Comment: 7 pages, 3 figure

Fusion reaction of halo nuclei: A real-time wave-packet method for three-body tunneling dynamics

We investigate fusion cross section of a nucleus with a valence neutron, using the time-dependent wave-packet method. For a stable projectile, in which the valence neutron is tightly bound (e_n < -3 MeV), the neutron could enhance the fusion probability when the matching condition of orbital energies are satisfied. In contrast, for a halo nucleus, in which the binding energy of the neutron is very small (e_n>-1 MeV), the fusion probability is hindered by the presence of the weakly bound neutron.Comment: Talk at Internaitonal Conference on "Reaction Mechanisms and Nuclear Structure at the Coulomb Barrier" (FUSION06), Venice, Italy, March 19-23, 200

Characteristics of a New Carbonaceous Chondrite, Metal-Rich-Lithology Found in the Carbonaceous Chondrite Breccia Aguas Zarcas

The Aguas Zarcas meteorite fell in Costa Rica on 23 April 2019 at 21:07 local time, with a total mass of about 27 kg. Hundreds of fusion-crusted stones ranging from 0.1 to 1868 g were recovered (The Meteoritical Bulletin). The meteorite was classified as a CM chondrite, but some lithlogies show a different texture to that of CM. In this study, we investigated the petrography, mineral-ogy, chemistry, and isotopic composition of an unusual Metal-rich-lithology from this fresh fall

Measuring Health Care Costs of Individuals with Employer-Sponsored Health Insurance in the U.S.: A Comparison of Survey and Claims Data

As the core nationally representative health expenditure survey in the United States, the Medical Expenditure Panel Survey (MEPS) is increasingly being used by statistical agencies to track expenditures by disease. However, while MEPS provides a wealth of data, its small sample size precludes examination of spending on all but the most prevalent health conditions. To overcome this issue, statistical agencies have turned to other public data sources, such as Medicare and Medicaid claims data, when available. No comparable publicly available data exist for those with employer-sponsored insurance. While large proprietary claims databases may be an option, the relative accuracy of their spending estimates is not known. This study compared MEPS and MarketScan estimates of annual per person health care spending on individuals with employer-sponsored insurance coverage. Both total spending and the distribution of annual per person spending differed across the two data sources, with MEPS estimates 10 percent lower on average than estimates from MarketScan. These differences appeared to be a function of both underrepresentation of high expenditure cases and underestimation across the remaining distribution of spending.

Forward Flux Sampling for rare event simulations

Rare events are ubiquitous in many different fields, yet they are notoriously difficult to simulate because few, if any, events are observed in a conventiona l simulation run. Over the past several decades, specialised simulation methods have been developed to overcome this problem. We review one recently-developed class of such methods, known as Forward Flux Sampling. Forward Flux Sampling uses a series of interfaces between the initial and final states to calculate rate constants and generate transition paths, for rare events in equilibrium or nonequilibrium systems with stochastic dynamics. This review draws together a number of recent advances, summarizes several applications of the method and highlights challenges that remain to be overcome.Comment: minor typos in the manuscript. J.Phys.:Condensed Matter (accepted for publication