Corruption under moral hazard

In this theoretical analysis, the"principal"can be the head of the tax collection agency (or"government"or even citizens), the"supervisor"can be the tax collector, and the"agent"can be the taxpayer. The principal, interested in controlling an agent's socially costly activity ("cheating"), hires the supervisor to save on monitoring costs. The agent may bribe the tax collector to suppress reporting, but bribery can be eliminated by the agency head if he institutes enough investigations and sets rewards high enough and penalties steep enough. When penalties and rewards are constrained, some corruption will exist even under a rational approach to pursuing the agency's objectives. Anti-corruption efforts will have higher costs than benefits unless they successfully address these constraints. The agency's implementation costs, and thus the scope for corruption, are defined by constraints on penalties and rewards relative to costs of monitoring and investigation. For example, if the agency head is extremely handicapped in his ability to detect bribery (by a high burden of proof and cost of investigation, and a civil service pay scale that is too flat and rigid), he cannot really reward good employees or make dishonest employees suffer. The analysis assumes that the principal can commit in advance to a certain likelihood of being caught engaging in bribery. Creating an independent anti-corruption commission (like those in Hong Kong and New South Wales) may be interpreted as a way of making such a commitment. In Hong Kong two-thirds of reports to the commission are made in full name, an indication that it has attained a reputation for independence and efficiency. The"whistleblower act"in the United states (promising rewards and protection for informants), as well as separation of powers and independent courts, also function as commitment. Corruption exists not only in poorly designed but also in sophisticated systems. It can profitably be reduced only by improving general incentives. Advances in courts, investigations, freedom of the press, and flow of information can allow more performance-based rewards and penalties.Environmental Economics&Policies,Economic Theory&Research,Corruption&Anitcorruption Law,Public Sector Corruption&Anticorruption Measures,Banks&Banking Reform

Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

The Taste for Variety: A Hedonic Analysis

Based on the model of consumers' variety-seeking behavior introduced by Anderson et al. (1992), this paper derives a hedonic price function for a households' consumption bundle. The price a consumer pays for her consumption bundle reflects the values of the underlying attributes of goods purchased but also accounts for any preference for variety that she might have. The empirical analysis is conducted for 3,240 German households and their expenditure on 182 different soft drinks over a six-month period. We find that consumers have a preference for variety in food consumption, ceteris paribus. Furthermore, the per-unit price is found to be significantly larger for higher income households, as well as households where the principal wage earner has a high level of education. Larger households tend to spend less on soft drinks per unit.consumer demand, taste for variety, food products, hedonic analysis, Germany, Food Consumption/Nutrition/Food Safety, C21, D12,

Modelling the evaporation of thin films of colloidal suspensions using Dynamical Density Functional Theory

Recent experiments have shown that various structures may be formed during the evaporative dewetting of thin films of colloidal suspensions. Nano-particle deposits of strongly branched `flower-like', labyrinthine and network structures are observed. They are caused by the different transport processes and the rich phase behaviour of the system. We develop a model for the system, based on a dynamical density functional theory, which reproduces these structures. The model is employed to determine the influences of the solvent evaporation and of the diffusion of the colloidal particles and of the liquid over the surface. Finally, we investigate the conditions needed for `liquid-particle' phase separation to occur and discuss its effect on the self-organised nano-structures

Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide

The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity of a solid-state co-planar waveguide is reported. Rydberg-Rydberg transitions, at frequencies between 25 GHz and 38 GHz, have been studied for states with principal quantum numbers in the range 30 - 35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used to reduce effects of blackbody radiation. Inhomogeneous, stray electric fields emanating from the surface of the waveguide have been characterized in frequency- and time-resolved measurements and coherence times of the Rydberg atoms on the order of 250 ns have been determined.Comment: 5 pages, 5 figure

Testing against changing correlation

A test for time-varying correlation is developed within the framework of a dynamic conditional score (DCS) model for both Gaussian and Student t-distributions. The test may be interpreted as a Lagrange multiplier test and modified to allow for the estimation of models for time-varying volatility in the individual series. Unlike standard moment-based tests, the score-based test statistic includes information on the level of correlation under the null hypothesis and local power arguments indicate the benefits of doing so. A simulation study shows that the performance of the score-based test is strong relative to existing tests across a range of data generating processes. An application to the Hong Kong and South Korean equity markets shows that the new test reveals changes in correlation that are not detected by the standard moment-based test.Some of the results in this paper were presented at the Time Series Workshop at the University of La Laguna, Tenerife, in January 2014 and at the Econometric Society Australasian meeting in Hobart in July, 2014. We would like to thank participants, particularly Yoosoon Chang, for helpful comments. Thanks also to Jukka Nyblom, our colleagues at Cambridge and two referees. We are grateful to the Keynes Fund for financial support. Simulations were run on the CamGrid cluster at the University of Cambridge

Bifurcation analysis of the behavior of partially wetting liquids on a rotating cylinder

We discuss the behavior of partially wetting liquids on a rotating cylinder using a model that takes into account the effects of gravity, viscosity, rotation, surface tension and wettability. Such a system can be considered as a prototype for many other systems where the interplay of spatial heterogeneity and a lateral driving force in the proximity of a first- or second-order phase transition results in intricate behavior. So does a partially wetting drop on a rotating cylinder undergo a depinning transition as the rotation speed is increased, whereas for ideally wetting liquids the behavior \bfuwe{only changes quantitatively. We analyze the bifurcations that occur when the rotation speed is increased for several values of the equilibrium contact angle of the partially wetting liquids. This allows us to discuss how the entire bifurcation structure and the flow behavior it encodes changes with changing wettability. We employ various numerical continuation techniques that allow us to track stable/unstable steady and time-periodic film and drop thickness profiles. We support our findings by time-dependent numerical simulations and asymptotic analyses of steady and time-periodic profiles for large rotation numbers

Experimental observation of nanoscale radiative heat flow due to surface plasmons in graphene and doped silicon

Owing to its two dimensional electronic structure, graphene exhibits many unique properties. One of them is a wave vector and temperature dependent plasmon in the infrared range. Theory predicts that due to these plasmons, graphene can be used as a universal material to enhance nanoscale radiative heat exchange for any dielectric substrate. Here we report on radiative heat transfer experiments between SiC and a SiO2 sphere which have non matching phonon polariton frequencies, and thus only weakly exchange heat in near field. We observed that the heat flux contribution of graphene epitaxially grown on SiC dominates at short distances. The influence of plasmons on radiative heat transfer is further supported with measurements for doped silicon. These results highlight graphenes strong potential in photonic nearfield and energy conversion devices.Comment: 4 pages, 3 figure