Flow Characteristics in a Crowded Transport Model

The aim of this paper is to discuss the appropriate modelling of in- and outflow boundary conditions for nonlinear drift-diffusion models for the transport of particles including size exclusion and their effect on the behaviour of solutions. We use a derivation from a microscopic asymmetric exclusion process and its extension to particles entering or leaving on the boundaries. This leads to specific Robin-type boundary conditions for inflow and outflow, respectively. For the stationary equation we prove the existence of solutions in a suitable setup. Moreover, we investigate the flow characteristics for small diffusion, which yields the occurence of a maximal current phase in addition to well-known one-sided boundary layer effects for linear drift-diffusion problems. In a one-dimensional setup we provide rigorous estimates in terms of $\epsilon$, which confirm three different phases. Finally, we derive a numerical approach to solve the problem also in multiple dimensions. This provides further insight and allows for the investigation of more complicated geometric setups

A PDE model for bleb formation and interaction with linker proteins

The aim of this paper is to further develop mathematical models for bleb formation in cells, including cell-membrane interactions with linker proteins. This leads to nonlinear reaction-diffusion equations on a surface coupled to fluid dynamics in the bulk. We provide a detailed mathematical analysis and investigate some singular limits of the model, connecting it to previous literature. Moreover, we provide numerical simulations in different scenarios, confirming that the model can reproduce experimental results on bleb initation

Do Tenure Differences Influence the Improvement of Quality of Rented Land? Empirical Evidence from Rural Ghana

The implications of migrant agricultural production for the environment have interested policy makers in sub-Saharan Africa of late. The impacts in the region of migrant destination may be short-term including initial felling of trees, intensive land use, and application of techniques. In the longer term, tenants are expected to adjust their techniques to that of the indigenous landowners. This paper explains how migrant tenants manage the quality of rented plots in the absence of clearly defined property rights with a survey data from rural area in Ghana. An empirical model explaining the probability to invest in land improvements is formulated. The empirical results indicate that tenure differences and income levels of migrants and indigenous landowners play a critical role in investments in land improvements.Land Economics/Use,

Novel microstructures and technologies applied in chemical analysis techniques

Novel glass and silicon microstructures and their application in chemical analysis are presented. The micro technologies comprise (deep) dry etching, thin layer growth and anodic bonding. With this combination it is possible to create high resolution electrically isolating silicon dioxide structures with aspect ratio's similar to those possible in silicon. Main applications are chemical separation methods such as high performance liquid chromatography (HPLC) or electrophoresis (HPCE). Beside these channel structures, a capillary connector with very low dead and mixing volume has been designed and fabricated for use in (correlation) electrophoresis, and tested by means of precision of consecutive single injection

Thermally assisted ion beam etching of polytetrafluoroethylene, a new technique for high aspect ratio etching of MEMS

In micromechanics, the etching of high aspect ratio structures in polymers is a prime technology. Normally, oxygen-based reactive ion etching or the LIGA technique are used to achieve this goal. This paper reintroduces a different idea to create deep trenches at high etch speed: the ion beam etching of Teflon. Because of its extraordinary properties the etch selectivity with respect to most other materials is over 1000. A model is proposed to explain the high etch rate and selectivity. Generally, the etching ions are highly energetic and material from different sources is sputtered on top of the sample. The high selectivity, high anisotropy, and sputtering of material are thought to be responsible for the forming of micrograss during etching a sample. Ways are given to decrease or increase this grass. The high potential of this technique will be discussed and applications will be shown. Especially, the use of etched Teflon for direct moulding is believed to become the main use of this techniqu

Miniaturised friction force measuring system for tribological research on magnetic storage devices

In this paper a silicon head slider suspension with integrated piezoresistive friction force sensors is presented. This device can be used for tribological research on magnetic rigid disk storage devices. Both the tangential and radial friction forces between the slider and disk, as well as a friction induced moment, can be measured simultaneously. Furthermore the normal load on the head slider can be measured. The paper focusses on design considerations and the realisation process of the suspension. Friction measurements are included to illustrate the feasibility of the system