Self-financing Roads

Mohring and Harwitz (1962) showed that, under certain conditions, an optimally designed and priced road would generate user toll revenues just sufficient to cover its capital costs. Several scholars subsequently explored the robustness of that finding. This paper briefly summarizes further research on the relationship between congestion-toll revenues and road costs. Despite its transparency, the self-financing theorem can lead to erroneous interpretations. The paper’s second part discusses three such possible fallacies. It uses a simple numerical model to investigate them. The model shows that the naïve interpretation of the Mohring-Harwitz rule may lead to substantial welfare losses. These losses are particularly prominent when the difference between capital and investment cost is confused and when balanced-budget constraints are imposed under second-best network conditions. In contrast, losses from imposing a balanced-budget constraint when economies or diseconomies of scale exist are surprisingly small

Influence of Sheep and Goats on the Natural Succession

A study was conducted to examine the effect of extensively-grazed pasture on the botanical composition. The trails were carried out in the year 1992 to 1995. For the study different breeds of sheep with the stocking rate of 30 sheep with their lambs / 2.6 ha were used. For the mixed-grazing a ratio of 20 sheep and 10 goats with their lambs / 2.6 ha were used. It is not possible to control all problem species with the help of sheepgrazing only. In contrast to that, it was concluded that goats grazed off all problem species quite effectively. Botanical composition has changed, resulting in an remarkable increase of herbs and legumes

Multiplicative Noise: Applications in Cosmology and Field Theory

Physical situations involving multiplicative noise arise generically in cosmology and field theory. In this paper, the focus is first on exact nonlinear Langevin equations, appropriate in a cosmologica setting, for a system with one degree of freedom. The Langevin equations are derived using an appropriate time-dependent generalization of a model due to Zwanzig. These models are then extended to field theories and the generation of multiplicative noise in such a context is discussed. Important issues in both the cosmological and field theoretic cases are the fluctuation-dissipation relations and the relaxation time scale. Of some importance in cosmology is the fact that multiplicative noise can substantially reduce the relaxation time. In the field theoretic context such a noise can lead to a significant enhancement in the nucleation rate of topological defects.Comment: 21 pages, LaTex, LA-UR-93-210

Influence of Different Breeds of Pigs to the Natural Succession

The aim of this study was to find out the effect of pigs on the natural succession. We used 4 different breeds of pigs for our investigations. Because of the grazing behaviour and their rooting activity the total number of plants increased up to 30%. But the vegetation quickly returned to conditions prior to rooting, if the rooting activity fails to happen. Rooting activity of pigs on floodplain soil and following grazing in the next spring after rooting permits seeds of different species of plants to germinate and develop in the plant free areas. These plants often have little chance to develop in closed grasslands. Especially small and light-loving plants get a chance to develop. Particularly the change of increasing rooting activity in autumn and intensive grazing in spring is realized by Duroc breed

Strangeness Enhancement in p+Ap+A and S+AS+A Interactions at SPS Energies

The systematics of strangeness enhancement is calculated using the HIJING and VENUS models and compared to recent data on $\,pp\,$, $\,pA\,$ and $\,AA\,$ collisions at CERN/SPS energies ($200A\,\, GeV\,$). The HIJING model is used to perform a {\em linear} extrapolation from $pp$ to $AA$. VENUS is used to estimate the effects of final state cascading and possible non-conventional production mechanisms. This comparison shows that the large enhancement of strangeness observed in $S+Au$ collisions, interpreted previously as possible evidence for quark-gluon plasma formation, has its origins in non-equilibrium dynamics of few nucleon systems. % Strangeness enhancement %is therefore traced back to the change in the production dynamics %from $pp$ to minimum bias $pS$ and central $SS$ collisions. A factor of two enhancement of $\Lambda^{0}$ at mid-rapidity is indicated by recent $pS$ data, where on the average {\em one} projectile nucleon interacts with only {\em two} target nucleons. There appears to be another factor of two enhancement in the light ion reaction $SS$ relative to $pS$, when on the average only two projectile nucleons interact with two target ones.Comment: 29 pages, 8 figures in uuencoded postscript fil

A New Elimination Rule for the Calculus of Inductive Constructions

Published in the post-proceedings of TYPES but actually not presented orally to the conferenceInternational audienceIn Type Theory, definition by dependently-typed case analysis can be expressed by means of a set of equations — the semantic approach — or by an explicit pattern-matching construction — the syntactic approach. We aim at putting together the best of both approaches by extending the pattern-matching construction found in the Coq proof assistant in order to obtain the expressivity and flexibility of equation-based case analysis while remaining in a syntax-based setting, thus making dependently-typed programming more tractable in the Coq system. We provide a new rule that permits the omission of impossible cases, handles the propagation of inversion constraints, and allows to derive Streicher's K axiom. We show that subject reduction holds, and sketch a proof of relative consistency

Measurement induced quantum-classical transition

A model of an electrical point contact coupled to a mechanical system (oscillator) is studied to simulate the dephasing effect of measurement on a quantum system. The problem is solved at zero temperature under conditions of strong non-equilibrium in the measurement apparatus. For linear coupling between the oscillator and tunneling electrons, it is found that the oscillator dynamics becomes damped, with the effective temperature determined by the voltage drop across the junction. It is demonstrated that both the quantum heating and the quantum damping of the oscillator manifest themselves in the current-voltage characteristic of the point contact.Comment: in RevTex, 1 figure, corrected notatio