An introduction to regular splines and their application for initial value problems of ordinary differential equations

This report describes an application of the general method of integrating initial value problems by means of regular splines for equations with movable singularities. By defining the families of functions that make up the regular splines such that they closely resemble the behaviour of the solutions of the differential equation, it is possible to trace the location of the singularities very precisely. To demonstrate this we treat Riccati differential equations. These are known to possess solutions with poles, usually of the first order. This type of differential equation or system arises in describing chemical or biological processes or more general control processes. To make the report self contained it starts with an introduction to regular splines and develops the algebraic tools for the manipulation of rational splines. After the description of the integration procedure, the asymptotic behaviour of the systematic error is investigated. An example exhibits the results obtained from the program given in Appendix A. Then Riccati equations are introduced and methods for the determination of the singularities are developed. These methods are tested numerically with several examples. The results are given in Appendix B

Double Checking the Doctor’s Credentials: The New Medical Expert Qualification Statute of MCARE

The problem of rapidly escalating premiums paid by doctors for medical malpractice insurance has plagued Pennsylvania in the last decade. These rates have uprooted Pennsylvania doctors from their local practices and hospitals in favor of out-of-state locations with lower rates. Furthermore, some Pennsylvania doctors and hospitals specializing in high-risk procedures have refused to perform high-risk surgeries or have limited their practice to more routine procedures

Quark-Gluon-Plasma Formation at SPS Energies?

By colliding ultrarelativistic ions, one achieves presently energy densities close to the critical value, concerning the formation of a quark-gluon-plasma. This indicates the importance of fluctuations and the necessity to go beyond the investigation of average events. Therefore, we introduce a percolation approach to model the final stage ($\tau > 1$ fm/c) of ion-ion collisions, the initial stage being treated by well-established methods, based on strings and Pomerons. The percolation approach amounts to finding high density domains, and treating them as quark-matter droplets. In this way, we have a {\bf realistic, microscopic, and Monte--Carlo based model which allows for the formation of quark matter.} We find that even at SPS energies large quark-matter droplets are formed -- at a low rate though. In other words: large quark-matter droplets are formed due to geometrical fluctuation, but not in the average event.Comment: 7 Pages, HD-TVP-94-6 (1 uuencoded figure

Thermalization of a pump-excited Mott insulator

We use nonequilibrium dynamical mean-field theory in combination with a recently implemented strong-coupling impurity solver to investigate the relaxation of a Mott insulator after a laser excitation with frequency comparable to the Hubbard gap. The time evolution of the double occupancy exhibits a crossover from a strongly damped transient at short times towards an exponential thermalization at long times. In the limit of strong interactions, the thermalization time is consistent with the exponentially small decay rate for artificially created doublons, which was measured in ultracold atomic gases. When the interaction is comparable to the bandwidth, on the other hand, the double occupancy thermalizes within a few times the inverse bandwidth along a rapid thermalization path in which the exponential tail is absent. Similar behavior can be observed in time-resolved photoemission spectroscopy. Our results show that a simple quasi-equilibrium description of the electronic state breaks down for pump-excited Mott insulators characterized by strong interactions.Comment: 8 pages, 4 figure

Rapid identification and differentiation of the vaccine strain Rac H from EHV 1 field isolates using a non-radioactive DNA probe

A method for rapid differentiation between the EHV 1 live vaccine strain Rac H and field isolates is described. Total DNA was isolated from virus-infected small scale cell cultures. DNA fragments digested with restriction endonuclease BamHI were separated, transfered and immobilized on filter membranes. A Digoxigenin-labeled probe derived from EHV 1 was used for hybridization. This probe hybridized specifically to sequences of the inverted terminal repeat region which in case of Rac H include a deletion of 0.8 kb. By comparing the different migration patterns after blot hybridization it could be shown that in 65 isolates from cases of abortion the live vaccine strain Rac H was not involve

Photo-induced states in a Mott insulator

We investigate the properties of the metallic state obtained by photo-doping carriers into a Mott insulator. In a strongly interacting system, these carriers have a long life-time, so that they can dissipate their kinetic energy to a phonon bath. In the relaxed state, the scattering rate saturates at a non-zero temperature-independent value, and the momentum-resolved spectral function features broad bands which differ from the well-defined quasi-particle bands of a chemically doped system. Our results indicate that a photo-doped Mott insulator behaves as a bad metal, in which strong scattering between doublons and holes inhibits Fermi-liquid behavior down to low temperature.Comment: 5 page

Expansion of the economic frontier : Paraguayan growth in the 1970's / 999

Includes bibliographical references (p. 18-20)