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Notizen: The unsteady (oscillatory) Stokes resistance is numerically computed for finite-length, circular cylinders using a first-kind, boundary integral formulation for low and moderate dimensionless frequencies. Translational oscillations parallel and perpendicular to the cylinder axis (axial and transverse oscillations) are considered. For arbitrarily oriented cylinders with length-to-width ratios in the range: 1/10≤a/b≤10, a simple, previously proposed, expression accurately (±5%) describes the oscillatory Stokes resistance at all frequencies in terms of steady Stokes and inviscid flow resistance parameters. Numerical calculations for spheroids agree with previous results; the results for cylinders and transverse oscillations of oblate spheroids are new.

Notizen: A theoretical analysis is developed for diffusion-controlled, heterogeneous reaction in a material with a bimodal poresize distribution. A configurational averaging procedure is used to describe a sparse, random network of macropore capillaries contained in a reactive, otherwise homogeneous matrix. The analysis is valid for a wide range of reactivities, and is particularly suited for conditions where reactant concentration varies on a length scale comparable to the diameter of, or the spacing between the macropores. The results depend on the reactivity on the matrix, the void volume of the macropore network, and the macropore to matrix diffusivity ratio. A local effectiveness parameter, which depends on the reactivity and macropore void volume, characterizes the reaction behavior in the material. An exact numerical solution is obtained that depends analytically on the parameters of the problem, and an accurate analytical representation is derived that depends very simply on the local effectiveness, the macropore void volume, and the diffusivity ratio; typical results are presented. The solution reduces to simplified models of the heterogeneous reaction in the low- and high-reactivity limits, where reactant concentration varies on a length scale that is large compared to the macropore spacing or small compared to the macropore diameter.

Notizen: The oscillatory motion of a finite-length, circular cylinder perpendicular to its symmetry axis in an incompressible, viscous fluid is described by the unsteady Stokes equations. Numerical calculations are performed using a first-kind, boundary-integral formulation for particle oscillation periods comparable to the viscous relaxation time. For high-frequency oscillations, a two-term, boundary layer solution is implemented that involves two, sequentially solved, second-kind integral equations. Good agreement is obtained between the boundary layer solution and fully numerical solutions at moderate oscillation frequencies. At the edges, where the base joins the side of the cylinder, the pressure and both components of tangential stress exhibit distinct, singular behaviors that are characteristic of steady, two-dimensional, viscous flow. Numerical calculations accurately capture the theoretically predicted singular behavior. The unsteady flow reversal process is initiated by a complex near-field flow reversal process that is inferred from the tangential stress distribution. A qualitative picture is constructed that involves the formation of three viscous eddies during the decelerating portion of the oscillation cycle: two attached to the ends of a finite-length cylinder, and a third that wraps around the cylinder centerline; the picture is similar to the results for axisymmetric flow. As deceleration proceeds, the eddies grow and coalesce at the cylinder edges to form a single eddy that encloses the entire particle. The remainder of the oscillatory flow cycle is insensitive to particle geometry and orientation. The macroscopic effect of the sharp edges is illustrated by considering ultrasonic, viscous dissipation in a dilute suspension. For a fixed particle-to-fluid density ratio, four different frequency regimes are identified. Four distinct viscous dissipation spectra are shown for different particle-to-fluid density ratios. The results indicate that particle geometry is important only for particles considerably less dense than the suspending fluid. The effect of edges is most apparent for disk- and rod-shaped particles.

Notizen: The Stokes resistance, added mass, and Basset force are numerically computed for finite-length, circular cross-section cylinders using a boundary integral formulation. Numerical results are presented for cylinders translating parallel and perpendicular to their symmetry axes with length-to-width ratios in the range: 0.01≤a/b≤100. There is good agreement with the limited experimental and numerical results of previous studies and slender-body theory. Simple, analytical formulas for the Stokes force, added mass, and Basset force of spheroids are contrasted with the numerical results for cylinders of the same aspect ratio. For some of these parameters, significant differences persist for disk- and rod-shaped particles.

Notizen: Karl Renner's political life encompasses the history of Austria's empire and her two twentieth-century republics, making him the foremost leader of Austrian democratic politics. Renner was also the most innovative theoretician on the nationalities question which plagued the Habsburg monarchy and the twentieth-century world. He was chancellor of Austria's first republic, leader of the right-wing Social Democrats, and president of the post-World War II Second Republic. A study of his life and politics offers a perspective on the origins of the moderate, adaptive, political personality and on the tension between ideology and accommodation to the point where it is difficult to determine what core of principle remained.

Notizen: The isoenzyme patterns of individual Xanthium leaves at various stages of development were determined by acrylamid electrophoresis. The Leaf Plastochron Index was used to measure leaf and plant age. The nature of the changes occurring during leaf development differed from enzyme to enzyme and from gfrom isoenzyme to isoenzyme; for instance, one of the glucose-6-phosphate dehydrogenases was peculiar to very young leaves, another to rapidly expanding leaves, and yet another to still older ones. On the other hand, the number of amylase isoenzymes merely increased with leaf age. Many of the changes in the isoenzyme patterns coincide with the cessation of cell division in the leaf or with the completion of leaf growth. The particular isoenzyme patterns of a given leaf depended on both leaf and plant age. While the isoenzyme patterns of leaves from maximum aldolase activity per unit protein and at a later stage than the leaves from the vegetative plants.

Notizen: From March to October 1986, ten one-day fishing trips were carried out on board a commercial fishing trawler operating in the Cross River estuary, Nigeria. The catch from 38 hauls was divided according to species, then separately measured and weighed.The maximum catch per effort (C/f) was 198 kg/h. Monthly means C/f were highest in March with 53.3 kg/h, and showed a negative trend towards the rainy season.More than 23 species belonging to 18 families were caught. Three species (Chrysichthys nigrodigatus, Pseudotolithus elongatus and Cynoglossus senegalensis) contributed over 80 % of the total monthly catch by weight.The length frequency distributions show that in both C. nigrodigitatus and P elongatus, 94% of the catch were juveniles.The biomass of the estuary (193 nm2) was estimated at 12.7 t/nm2 in March and 2.5 t/nm2 in October.〈section xml:id="abs1-2"〉〈title type="main"〉ZusammenfassungSchleppnetzfischerei im Cross River ästuar, NigeriaWährend einer Untersuchung der Schleppnetzfischerei im Cross River Astuar, Nigeria, von Mai bis Oktober 1986 wurden 10 Tagesfischereien an Bord eines kommerziellen Kutters, der im Cross River ästuar fischt, durchgeführt.Der Fang von 38 Hols wurde nach Arten sortiert, gamessen und gewogen. Der maximale Fang pro Aufwandeinheit (C/f) lag bei 198 kg/h. Die Monatsmittel des C/f waren mit 53.3 kg/h im März am höchsten, und nahmen zur Regenzeit hin ab.Mehr als 23 Arten aus 18 Familien wurden gefangen. Drei Arten (Chrysichthys nigrodigitatus, Pseudotolithus elongatus, Cynoglossus senegalensis) tragen gewichtsmäßig mir über 80% zum monatli-chen Gesamtfang bei.Die Längenverteilungen zeigen, daß 94% des Fanges von C. nigrodigitatus und P elongatus aus juvenilen Tieren bestanden hat.Die Biomasse des ästuars (193 sm2) wurde mit 12,7 t/sm2 im März und 2,5 t/sm2 im Oktober berechnet.〈section xml:id="abs1-3"〉〈title type="main"〉RésuméInvestigations sur la pêche au chalut dans L'estuaire de Cross River, NigeriaDe mars a octobre 1986, dix campagnes d'un jour ont été effectuées i bord d'un chalut commercial qui operant dans l'estuaire de Cross River, Nigeria.Les prises maximales par unité d'effort (C/f itaient de l'ordre de 198 kg/h. Les moyennes men-suelles des C/f, enregistrant des prises maximales de 53, 3 kg/h en mars, ont révélé une tendance négative aux abords de la saison des pluies. Plus de 23 espéces appartenant sà 18 familles ont été prises lors de ces campagnes. Trois espées (Chrysichthys nigrodigitatus, Pseudotolithus elongatus, et Cynoglossus senegalensis) ont contribui plus de 80% du poids total des prises mensuelles.La distribution des fréquences de longueur a mis en évidence que les prise de C. nigrodigitatus et P. elongatusétaient constituées sà 94 % par des juvéniles.La biomasse de l'estuaire (193 milles marins2) a été estimée en mars h 12,7 t/mille marin2, et sà 2,5 t/mille marin2 en octobre

Notizen: Systems theorists introduced the concept of ‘support’ to permit explanations of political stability and instability. Yet most attempts to verify the existence of a relationship between support and stability empirically have dealt with wellestablished political systems, and have relied on data collected at one point in time. This paper reports an initial effort to examine the growth of support for a new political regime using a series of sample surveys providing data on changes in the level of support over time.