Unemployment and the Immigration Surplus

Within a small open economy fair wage model with unemployment of unskilled workers, we show that exogenous unskilled immigration increases the welfare of natives if the elasticity of the inverse labour demands exceeds a positive finite threshold. This threshold depends positively on the displacement ratio of native workers by immigrants and negatively on the share of immigrants in the unskilled workforce.Immigration, Unemployment, Fair Wages

Dynamics and efficiency of a self-propelled, diffusiophoretic swimmer

Active diffusiophoresis - swimming through interaction with a self-generated, neutral, solute gradient - is a paradigm for autonomous motion at the micrometer scale. We study this propulsion mechanism within a linear response theory. Firstly, we consider several aspects relating to the dynamics of the swimming particle. We extend established analytical formulae to describe small swimmers, which interact with their environment on a finite lengthscale. Solute convection is also taken into account. Modeling of the chemical reaction reveals a coupling between the angular distribution of reactivity on the swimmer and the concentration field. This effect, which we term "reaction induced concentration distortion", strongly influences the particle speed. Building on these insights, we employ irreversible, linear thermodynamics to formulate an energy balance. This approach highlights the importance of solute convection for a consistent treatment of the energetics. The efficiency of swimming is calculated numerically and approximated analytically. Finally, we define an efficiency of transport for swimmers which are moving in random directions. It is shown that this efficiency scales as the inverse of the macroscopic distance over which transport is to occur.Comment: 16 pages, 11 figure

Non-monotonic fluctuation spectra of membranes pinned or tethered discretely to a substrate

The thermal fluctuation spectrum of a fluid membrane coupled harmonically to a solid support by an array of tethers is calculated. For strong tethers, this spectrum exhibits non-monotonic, anisotropic behavior with a relative maximum at a wavelength about twice the tether distance. The root mean square displacement is evaluated to estimate typical membrane displacements. Possible applications cover pillar-supported or polymer-tethered membranes.Comment: 4 pages, 5 figure

I feel good! Gender differences and reporting heterogeneity in self-assessed health

For empirical analysis and policy-oriented recommendation, the precise measurement of individual health or well-being is essential. The problem with variables based on questionnaires such as self-assessed health is that the answer may depend on individual reporting behaviour. Moreover, if individual‟s health perception varies with certain attitudes of the respondent reporting heterogenei-ty may lead to index or cut-point shifts of the health distribution, causing estimation problems. We analyse the reporting behaviour of individuals on their self-assessed health status, a five-point categorical variable. We explore observed heterogeneity in categorical variables and include unob-served individual heterogeneity using German panel data. Estimation results show different im-pacts of socioeconomic and health related variables on the five subscales of self-assessed health. Moreover, the answering behaviour varies between female and male respondents, pointing to gen-der specific perception and assessment of diseases. Reporting behaviour on self-assessed health questions in surveys is problematic due to a possible heterogeneity. Hence, in case of reporting heterogeneity, using self-assessed measures in empirical studies may be misleading or at least ambiguous.reporting heterogeneity, generalized ordered probit, self-assessed health

Payout Policy in the 21st Century

We survey 384 CFOs and Treasurers, and conduct in-depth interviews with an additional two dozen, to determine the key factors that drive dividend and share repurchase policies. We find that managers are very reluctant to cut dividends, that dividends are smoothed through time, and that dividend increases are tied to long-run sustainable earnings but much less so than in the past. Rather than increasing dividends, many firms now use repurchases as an alternative. Paying out with repurchases is viewed by managers as being more flexible than using dividends, permitting a better opportunity to optimize investment. Managers like to repurchase shares when they feel their stock is undervalued and in an effort to affect EPS. Dividend increases and the level of share repurchases are generally paid out of residual cash flow, after investment and liquidity needs are met. Financial executives believe that retail investors have a strong preference for dividends, in spite of the tax disadvantage relative to repurchases. In contrast, executives believe that institutional investors as a class have no strong preference between dividends and repurchases. In general, management views provide at most moderate support for agency, signaling, and clientele hypotheses of payout policy. Tax considerations play only a secondary role. By highlighting where the theory and practice of corporate payout policy are consistent and where they are not, we attempt to shed new light on important unresolved issues related to payout policy in the 21st century.

On the attractors of two-dimensional Rayleigh oscillators including noise

We study sustained oscillations in two-dimensional oscillator systems driven by Rayleigh-type negative friction. In particular we investigate the influence of mismatch of the two frequencies. Further we study the influence of external noise and nonlinearity of the conservative forces. Our consideration is restricted to the case that the driving is rather weak and that the forces show only weak deviations from radial symmetry. For this case we provide results for the attractors and the bifurcations of the system. We show that for rational relations of the frequencies the system develops several rotational excitations with right/left symmetry, corresponding to limit cycles in the four-dimensional phase space. The corresponding noisy distributions have the form of hoops or tires in the four-dimensional space. For irrational frequency relations, as well as for increasing strength of driving or noise the periodic excitations are replaced by chaotic oscillations.Comment: 9 pages, 5 figure

Some Behavioural Responses Of Limicolaria aurora Exposed To Gramoxone

The effects of 0.5, 1.0, 1.5 and 2.0 % of combined oral and dermal single-application of 0.1 M concentration of gramoxone (contact herbicide, paraquat chloride) on Limicolaria aurora were determined and compared with control using Amaranthus sp. as bait. Responses were measured through normal feeding and crawling, head retraction into the shell, swelling, excessive mucus secretion, lack of response to mechanical stimuli (mortality). Results showed no effects on controls. Snails exposed to gramoxone fed less as contamination increased. Gramoxone is molluscicidal, it can also result in behaviour–modifying observations in snails which are non-target organisms in the ecosystem. Key words: African giant land snail, gramoxone, ecotoxicology. Nigerian Journal of Physiological Sciences Vol.19(1&2) 2004: 82-8

Noise-Induced Transition from Translational to Rotational Motion of Swarms

We consider a model of active Brownian agents interacting via a harmonic attractive potential in a two-dimensional system in the presence of noise. By numerical simulations, we show that this model possesses a noise-induced transition characterized by the breakdown of translational motion and the onset of swarm rotation as the noise intensity is increased. Statistical properties of swarm dynamics in the weak noise limit are further analytically investigated.Comment: 7 pages, 7 figure