Apparatus for extraction and separation of a preferentially photo-dissociated molecular isotope into positive and negative ions by means of an electric field

Molecules of one and the same isotope were preferentially photodissociated by a laser and an ultraviolet source, or by multiphoton absorption of laser radiation. The resultant ions were confined with a magnetic field, moved in opposite directions by an electric field, extracted from the photodissociation region by means of screening and accelerating grids, and collected in ducts

Vertical shear instability in accretion disc models with radiation transport

The origin of turbulence in accretion discs is still not fully understood. While the magneto-rotational instability is considered to operate in sufficiently ionized discs, its role in the poorly ionized protoplanetary disc is questionable. Recently, the vertical shear instability (VSI) has been suggested as a possible alternative. Our goal is to study the characteristics of this instability and the efficiency of angular momentum transport, in extended discs, under the influence of radiative transport and irradiation from the central star. We use multi-dimensional hydrodynamic simulations to model a larger section of an accretion disc. First we study inviscid and weakly viscous discs using a fixed radial temperature profile in two and three spatial dimensions. The simulations are then extended to include radiative transport and irradiation from the central star. In agreement with previous studies we find for the isothermal disc a sustained unstable state with a weak positive angular momentum transport of the order of $\alpha \approx 10^{-4}$. Under the inclusion of radiative transport the disc cools off and the turbulence terminates. For discs irradiated from the central star we find again a persistent instability with a similar $\alpha$ value as for the isothermal case. We find that the VSI can indeed generate sustained turbulence in discs albeit at a relatively low level with $\alpha$ about few times $10^{-4}$Comment: 12 pages, 24 figures, accepted for publication in Astronomy & Astrophysic

Task Specific Uncertainty in Coordinate Measurement

Task specific uncertainty is the measurement uncertainty associated with the measurement of a specific feature using a specific measurement plan. This paper surveys techniques developed to model and estimate task specific uncertainty for coordinate measuring systems, primarily coordinate measuring machines using contacting probes. Sources of uncertainty are also reviewed

A note on couette flow of nematic crystals according to the Ericksen–Leslie theory

In order to model the flow of nematic crystals, the theoretical framework according to Ericksen and Leslie is applied. The essentials of the theory are compiled and then specialized to Couette flow. The profiles for linear velocity and orientation angle will be computed and, in particular, we shall also study the rise in temperature due to viscous dissipation, which is frequently ignored by mechanicians. Analytical and numerical solutions for the fields are derived for different boundary conditions and will subsequently be discussed.TU Berlin, Open-Access-Mittel - 201

Meson retardation in deuteron photodisintegration above pi-threshold

Photodisintegration of the deuteron above pi-threshold is studied in a coupled channel approach including N Delta- and pi d-channels with pion retardation in potentials and exchange currents. A much improved description of total and differential cross sections in the energy region between pi-threshold and 400-450 MeV is achieved.Comment: 12 pages revtex including 5 postscript figure

Changing regional images; are regional marketing campaigns successful?

An important element in the urban and regional development strategy of many local and regional governments is geographical marketing. The process of geographical marketing combines promotional, spatial and organisational activities, and can be aimed at various groups. In 1989 a marketing campaign was started by the province of Groningen, in the northern part of the Netherlands. This campaign, which is still being carried on, has used various means of communication: advertisements in newspapers and magazines, and radio and television commercials. It has been aimed at entrepreneurs and at the general public as well. An ex ante study of the public image of Groningen was carried out before the start of the campaign. For this purpose a random sample of the Dutch population was inquired by telephone. Since then similar inquiries were carried out every two years, in order to measure the effects of the campaign. In these inquiries the image of the provinces of Friesland and Noord-Brabant was measured along with that of Groningen, and used for reference. The availability of this kind of data for a period of twelve years, measured at regular intervals, provides an opportunity to study the development of regional images through time. In this paper the data of the inquiries will be analysed. One of the main questions to be answered in the paper relates to the pace and the nature of the changes in image, observed in all three provinces. The second question specifically deals with the influence of the marketing campaign on the image of Groningen.