Do capital buffers mitigate volatility of bank lending? A simulation study

Critics claim that capital requirements can exacerbate credit cycles by restricting lending in an economic downturn. The introduction of Basel 2, in particular, has led to concerns that risksensitive capital charges are highly correlated with the business cycle. The Basel Committee is contemplating a revision of the Basel Accord by introducing counter-cyclical capital buffers. Others claim that capital buffers are already large enough to absorb fluctuations in credit risk. We address the question of the pro-cyclical effects of capital requirements in a general framework which takes into account banks' potential adjustment strategies. We develop a dynamic model of bank lending behavior and simulate different regulatory frameworks and macroeconomic scenarios. In particular, we address two related questions in our simulation study: How do business fluctuations affect capital requirements and bank lending? To what extent does the capital buffer absorb fluctuations in the level of mimimum required capital? --Minimum capital requirements,regulatory capital,capital buffer,cyclical lending,pro-cyclicality

Nutrient cycle on organic farms: stall balance of a suckler herd and beef bulls

In organic agriculture, the internal farm nutrient cycle must be quantified to ensure high system productivity along with environmentally sound production processes. In contrast to common farmgate and field balances, budgeting at the stable level is seldom undertaken. When budgeting mixed farming systems, a substantial lack of nutrients can be detected in the nutrient flow chain "forage and straw input - stable - manure output". Therefore, stable balances focus on a central component of whole farm nutrient budgets for developing efficient nutrient management strategies. At the experimental farm for organic agriculture Wiesengut in Hennef, Germany, all solid mass flows for a suckler herd and a herd of beef bulls were measured. Relative balance values obtained for dry matter and C (45 to 56%), N (16 to 36%), P (-7 to 22.5%), K (0 to 13%) and ash (-4 to 7%) showed a wide range. Balances are very sensitive to variations in mass flow and nutrient content for components with high nutrient contents and/or a large contribution to total mass flow (e.g. manure, silage). In developing strategies to minimize N losses, by reducing N surplus in the ration, it has to be considered, that in contrast to dairy farms, a suckler herd for beef production integrated in an organic farm has to adapt to crop production demands. from: HAAS, G., B. CASPARI, U. KÖPKE 2002: Nutrient cycle on organic farms: stall balance of a suckler herd and beef bulls. Nutrient Cycling in Agroecosystems 64, 225-230

Controlled nonuniformity in macroporous silicon pore growth

Photoelectrochemical etching of uniform prestructured silicon wafers in hydrofluoric acid containing solutions yields periodic structures that can be applied to two- and three-dimensional photonic crystals or microfluidics. Here we demonstrate experimentally macroporous silicon etching initiated by a nonuniform predefined lattice. For conveniently chosen parameters we observe a stable growth of pores whose geometrical appearance depends strongly on the spatially different nucleation conditions. Moreover, we show preliminary results on three-dimensionally shaped pores. This material can be used to realize hybrid photonic crystal structures and incorporate waveguides in three-dimensional photonic crystals

Epistemological Perspectives on Simulation

This special section includes papers originally presented at a workshop on \'Epistemological Perspectives on Simulation\' in July 2004 at the University of Koblenz, in which some thirty colleagues participated. It had been our impression that there was (and still is) a small, but growing number of researchers who are interested in investigating the preconditions of successfully deploying simulation as a research tool. We were convinced that discussing the epistemological status of simulation in a cross-disciplinary setting could contribute to a deeper understanding of relevant issues and so it proved.Simulation, Epistemology, Methodology

Full PIC simulation of a first ACHIP experiment @ SINBAD

In laser illuminated dielectric accelerators (DLA) high acceleration gradients can be achieved due to high damage thresholds of the materials at optical frequencies. This is a necessity for developing more compact particle accelerator technologies. The Accelerator on a CHip International Program (ACHIP) funded by the Gordon and Betty Moore Foundation is researching such devices. DESY Hamburg is part of the collaboration. The dedicated accelerator research facility SINBAD is particularly well suited for DLA experiments at relativistic electron energies. High quality beams and short bunch lengths are anticipated from the ARES linac which is currently under construction at SINBAD. The aim of the experiment is the injection of a short electron bunch from the ARES linac into a DLA. In this study the results of one of the first possible experiments at the facility are estimated via a combination of particle-in-cell (PIC) and tracking simulations. ASTRA is used to simulate an electron bunch from the ARES linac at a suitable working point. The dielectric part of the setup will be simulated using the PIC code from CST Particle Studio incorporating the retrieved bunch from the ASTRA simulation. The energy spectra of the electron bunches are calculated as would be measured from a spectrometer dipole with and without the laser fields