Time Domain Studies of X-ray Shot Noise in Cygnus X-1

We investigate the variability of Cygnus X-1 in the context of shot moise models, and employ a peak detection algorithm to select individual shots. For a long observation of the low, hard state, the distribution of time intervals between shots is found to be consistent with a purely random process, contrary to previous claims in the literature. The detected shots are fit to several model templates and found to have a broad range of shapes. The fitted shots have a distribution of timescales from below 10 milliseconds to above 1 second. The coherence of the cross spectrum of light curves of these data in different energy bands is also studied. The observed high coherence implies that the transfer function between low and high energy variability is uniform. The uniformity of the tranfer function implies that the observed distribution of shot widths cannot have been acquired through Compton scattering. Our results in combination with other results in the literature suggest that shot luminosities are correlated with one another. We discuss how our experimental methodology relates to non-linear models of variability.Comment: Accepted for publication in Astrophysical Journal on July 16, 200

Philanthropy and the Regeneration of Community Democracy

The underlying assumption among foundations of all kinds has been that productive change comes from technical intervention through programs and services. However, various pressures, including frustration with results that all too often seem superficial and disappointing, have led to growing interest in something beyond traditional approaches. This different approach -- variously described as community or civic capacity building, community-based problem solving, democratic institution building, comprehensive community change, and so on -- is sometimes met with skepticism. This report is intended to give greater assurance that this "other" course for communities with support from philanthropy is indeed possible

The Focke Helicopter

This report presents some of the problems concerning tests of helicopters, such as forced landings, controllability and stability, general safety, piloting maneuvers, performance, servicing, and the production of lift of a propeller. Test flights are described including a 67.67 mph flight by Hanna Reitsch

Rapid Profiling of Marine Notches Using a Handheld Laser Distance Meter

A rapid, single-user profiling method for rocky shores is described. The Leica Disto D8 handheld laser distance meter measures distance up to 100 m and inclination in 360 degrees. It automatically calculates horizontal distance and vertical elevation. Memory storage accommodates data for 30 measurement points, allowing easy plotting of shore profiles. This technique allows even inaccessible, dangerous, and overhanging cliff faces to be evaluated faithfully and within minutes. It is a major improvement over standard methods that often involve risky coasteering and climbing. Examples are given from marine notches in Thailand

BoGSy:ein Informationssystem für Botanische Gärten

Botanische Gärten bieten den Botanischen Instituten die Grundlage für deren Forschungen und Besuchern einen Einblick in die Pflanzenwelt. Die mit dem Wissenschaftszweig der Botanik entstanden Universitätsgärten haben ihren Mittelpunkt in der Botanischen Forschung und Lehre, vor allem in den Bereichen Taxonomie und Ökologie. Die Grundlagen und der Inhalt der Botanischen Arbeit sind demnach insbesondere Sammlungen. Darüber hinaus erfordert die Teilnahme im IPEN (International Plant Exchange Network) seit einigen Jahren die Einhaltung strenger Kriterien der CBD (Convention on Biological Diversity) beim Austausch von Samen und Pflanzenmaterial. Die Entwicklung eines Datenbank gestützten Informationssystems für Botanische Gärten wird durch eine Reihe von Beobachtungen motiviert und muss diverse Randbedingungen beachten. Dies wird im Folgenden genauer erläutert. Sodann werden der Entwurf und eine erste Realisierung des Informationssystems BoGSy beschrieben, welches an der Universität Münster entwickelt wird und diesen Bedingungen genügt.<br/

Relativistic Effects on Interchannel Coupling in Atomic Photoionization: The Photoelectron Angular Distribution of Xe

Measurements of the photoelectron angular-distribution asymmetry parameter β for Xe 5s photoionization have been performed in the 80–200 eV photon-energy region. The results show a substantial deviation from the nonrelativistic value of β=2 and provide a clear signature of significant relativistic effects in interchannel coupling

Validity of the Independent-Particle Approximation in X-Ray Photoemission: The Exception, Not the Rule

A combined experimental and theoretical study of argon valence photoionization illustrates the discovery of the broad lack of validity of the independent-particle approximation (IPA) for x-ray photoemission. In addition to previously known breakdowns of the IPA, which are limited to high photon energies and regions very near threshold, the observed breakdown in photoionization at intermediate energies demonstrates generally that the IPA is valid only in very restricted domains. These restrictions are expected to be relevant throughout the periodic table, with consequences for a wide variety of applications

Beyond the Dipole Approximation: Angular-Distribution Effects in the 1s Photoemission from Small Molecules

Over the past two decades, the dipole approximation has facilitated a basic understanding of the photoionization process in atoms and molecules. Recent experiments on the 1s inner shells of small molecules at relatively low photon energies (⩽ 1000 eV) show strong nondipole effects. They are significant and measurable at energies close to threshold, in conflict with a common assumption that the dipole approximation is valid for photon energies below 1 keV

Large Nondipole Effects in the Angular Distributions of K-Shell Photoelectrons from Molecular Nitrogen

Measurements of angular distributions of K-shell electrons photoejected from molecular nitrogen are reported which reveal large deviations at relatively low photon energies ( ħω≤500eV) from emission patterns anticipated from the dipole approximation to interactions between radiation and matter. A concomitant theoretical analysis incorporating the effects of electromagnetic retardation attributes the observed large nondipole behaviors in N2 to bond-length-dependent terms in the E1⊗(E2,M1) photoelectron emission amplitudes which are indicative of a potentially universal nondipole behavior in molecular photoionization