Stress Interference in Axisymmetric Torsion of a Transeversely Isotropic Body

An unbounded transversely isotropic body of revolution containing two spheroidal cavities is subjected to torsion about its axis of elastic symmetry, which coincides with its axis of revolution. At large' distances from the cavities the elastic field approaches the Saint-Venant solution for the torsion of a circular cylinder. The elasticity solution is obtained in series form and numerical results presented for the case of two spherical cavities. Of primary interest is the degree of stress interference between the. two perturbations, as a function of the spacing of the cavities and the values of the elastic constants.Air Force Office of Scientific Research Grant No. AFOSR 82-004

The Choice of Technology in Russian Agriculture: An Application of the Induced Innovation Hypothesis

Even after more then ten years after the beginning of the transition process, Russian agriculture shows only limited sign of a recovery. Production has not reached the level of the pre-transition period and investment is still on a very low level. In this paper we use the "Theory of Induced Innovation" in order to access the development of production structures in Russia and to identify the major obstacles for restructuring. We argue that due to multiple market failure (capital, labour) and inappropriate institutional arrangements inherited from Soviet times hinder the development of Russian agriculture. Both reasons causes that agricultural enterprises have difficulties with regard to an adjustment of factor input and production corresponding to the real scarcities of production factors. Agricultural policies based on subsidizing factor use or minimum prices will be an inefficient approach to solve the problems. A promising approach instead would be encouraging market transactions and fostering the integration of agricultural enterprises in the regional and domestic factor and product markets.technical change, efficiency, Russia, agriculture, induced innovation theory, Agribusiness, Q11, Q16,

Life Cycle and Cohort Productivity in Economic Research: The Case of Germany

We examine the research productivity of German academic economists over their life cycles. It turns out that the career-patterns of research productivity as measured by journal publications are characterized by marked cohort effects. Moreover, the life-cycles of younger German economists are hump-shaped and closely resemble the life cycles identified for U.S. economists, whereas the life-cycles of older German economists are much flatter. Finally, we find that not only productivity, but also research quality follows distinct life cycles. Our study employs econometric techniques that are likely to produce estimates that are more trustworthy than previous estimates.research productivity, life cycles, cohort effects

Evaluation of Researchers: A Life Cycle Analysis of German Academic Economists

In this paper we ague that any meaningful bibliometric evaluation of researchers needs to take into account that research productivity follows distinct life cycles. Using an encompassing data set portraying the research behavior of German academic economists, we first show that research productivity crucially depends on career age and vintage. Based on the identified effects, we develop a simple formula that shows how a researcher’s performance compares to that of his or her peers. This kind of information may serve as an input for performance-related remuneration and track-record based allocation of research grants. We then go on to investigate the persistence of individual productivity. The Persistence issue is of special importance in the academic labor market because of the irrevocable nature of tenure. Finally, we show how life cycle considerations can be used in evaluations of university departments in order to render the resulting rankings insensitive to the age structure of the evaluated faculties.research productivity, performance evaluation, life cycles, rankings

BIOMONITORING OF ECOLOGICAL STATE OF THE ENVIRONMENT IN THE ZONE OF INFLUENCE OF THE “CHERVONOGRADSKA” MINE OF THE LVIV-VOLYN COALFIELD

Coal mining has a very negative impact on the environment and it requires monitoring studies to assess the degree of environmental pollution

Deflection of a Viscoelastic Cantilever under a Uniform Surface Stress: Applications to Static-mode Microcantilever Sensors Undergoing Adsorption

The equation governing the curvature of a viscoelastic microcantilever beam loaded with a uniform surface stress is derived. The present model is applicable to static-mode microcantilever sensors made with a rigid polymer, such as SU-8. An analytical solution to the differential equation governing the curvature is given for a specific surface stress representing adsorption of analyte onto the viscoelastic beam’s surface. The solution for the bending of the microcantilever shows that, in many cases, the use of Stoney’s equation to analyze stress-induced deflection of viscoelastic microcantilevers (in the present case due to surface analyte adsorption) can lead to poor predictions of the beam’s response. It is shown that using a viscoelastic substrate can greatly increase sensitivity (due to a lower modulus), but at the cost of a longer response time due to viscoelasticcreep in the microcantilever. In addition, the effects of a coating on the cantilever are considered. By defining effective moduli for the coated-beam case, the analytical solution for the uncoated case can still be used. It is found that, unlike the case of a silicon microcantilever, the stress in the coating due to bending of a polymer cantilever can be significant, especially for metalcoatings. The theoretical results presented here can also be used to extract time-domain viscoelasticproperties of the polymermaterial from beam response data

Desarrollo y ambivalencias de la teoría económica de Marx

With the deep economic crisis we face since 2008 also the interest in Marxian theories increased worldwide. This was not really surprising: while in Marx’s economic theory crises play an important role, they are nearly neglected in mainstream economics. They appear there as mere accidents, which could be prohibited by flexible markets (this is the belief of neoclassical economists) or by an appropriate economic policy (the belief of the Keynesians). But talking about Marxian economic theory, we should always have in mind, that there is a certain development in Marx’s thinking as well as there are certain ambivalences in basic theoretical concepts. In traditional Marxism, which mostly tried to present Marxian theory as a complete and perfect building, especially such ambivalences were often negIected or even denied. In the following I will give a short overview about the main stages of Marx’s theoretical development, and then I will focus on the ambivalences of Marx’s mature theoretical work.Con la profunda crisis económica a la que nos enfrentamos desde 2008 ha aumentado también el interés por la teoría marxiana en todo el mundo. Pero esto verdaderamente no es algo que deba sorprender: mientras que en la teoría económica de Marx las crisis desempeñan un papel importante, en la economía convencional son prácticamente ignoradas. en ésta aparecen como meros accidentes, que podrían ser evitados por medio de mercados flexibles (ésa es la creencia de los economistas neoclásicos) o por medio de una política económica adecuada (la creencia de los keynesianos). Pero al hablar de la teoría económica marxiana deberíamos tener siempre en cuenta que hay un cierto desarrollo en el pensamiento de Marx, así como hay ciertas ambivalencias en conceptos teóricos básicos. en el marxismo tradicional, que en su mayoría ha intentado presentar la teoría marxiana como un edificio completo y perfecto, esas ambivalencias eran a menudo obviadas o incluso negadas. A continuación voy a dar una breve descripción de las principales etapas del desarrollo teórico de Marx, y después me centraré en las ambivalencias de su obra teórica de madurez

Surface-confined 2D polymerization of a brominated copper-tetraphenylporphyrin on Au(111)

A coupling-limited approach for the Ullmann reaction-like on-surface synthesis of a two-dimensional covalent organic network starting from a halogenated metallo-porphyrin is demonstrated. Copper-octabromo-tetraphenylporphyrin molecules can diffuse and self-assemble when adsorbed on the inert Au(111) surface. Splitting-off of bromine atoms bonded at the macrocyclic core of the porphyrin starts at room temperature after the deposition and is monitored by X-ray photoelectron spectroscopy for different annealing steps. Direct coupling between the reactive carbon sites of the molecules is, however, hindered by the molecular shape. This leads initially to an ordered non-covalently interconnected supramolecular structure. Further heating to 300{\deg}C and an additional hydrogen dissociation step is required to link the molecular macrocycles via a phenyl group and form large ordered polymeric networks. This approach leads to a close-packed covalently bonded network of overall good quality. The structures are characterized using scanning tunneling microscopy. Different kinds of lattice defects and, furthermore, the impact of polymerization on the HOMO-LUMO gap are discussed. Density functional theory calculations corroborate the interpretations and give further insight into the adsorption of the debrominated molecule on the surface and the geometry and coupling reaction of the polymeric structure.Comment: 9 pages, 6 figure