Biaxial nematic phases in fluids of hard board-like particles

We use density-functional theory, of the fundamental-measure type, to study the relative stability of the biaxial nematic phase, with respect to non-uniform phases such as smectic and columnar, in fluids made of hard board-like particles with sizes $\sigma_1>\sigma_2>\sigma_3$. A restricted-orientation (Zwanzig) approximation is adopted. Varying the ratio $\kappa_1=\sigma_1/\sigma_2$ while keeping $\kappa_2=\sigma_2/\sigma_3$, we predict phase diagrams for various values of $\kappa_2$ which include all the uniform phases: isotropic, uniaxial rod- and plate-like nematics, and biaxial nematic. In addition, spinodal instabilities of the uniform phases with respect to fluctuations of the smectic, columnar and plastic-solid type, are obtained. In agreement with recent experiments, we find that the biaxial nematic phase begins to be stable for $\kappa_2\simeq 2.5$. Also, as predicted by previous theories and simulations on biaxial hard particles, we obtain a region of biaxility centred on $\kappa_1\approx\kappa_2$ which widens as $\kappa_2$ increases. For \kappa_2\agt 5 the region $\kappa_2\approx\kappa_1$ of the packing-fraction vs. $\kappa_1$ phase diagrams exhibits interesting topologies which change qualitatively with $\kappa_2$. We have found that an increasing biaxial shape anisotropy favours the formation of the biaxial nematic phase. Our study is the first to apply FMT theory to biaxial particles and, therefore, it goes beyond the second-order virial approximation. Our prediction that the phase diagram must be asymmetric is a genuine result of the present approach, which is not accounted for by previous studies based on second-order theories.Comment: Preprint format. 18 pages, 5 figure

Optimising grass supply, labour, economy and mind-set to create added value from grazing

Grazing provides multiple benefits to farmers and to the wider society. While the ecosystem services provided to society are certainly appreciated, they are thus far hardly rewarded. This paper discusses topics related to creating added value from grazing by optimising grass supply, labour, economy and mind-set. New promising business models are presented, in which farmers are financially rewarded for their added value contributions. An example of a grazing system that is easy to implement is given, the "New Dutch Grazing", which optimises labour and grass utilisation. Finally, the importance of the mind-set of the farmer is discussed. Farmers are key actors when it comes to maintaining and improving grazing systems since they decide on the day-to-day management on the farm. When developing stimulating initiatives, this should be taken into account. Special attention should be paid to young farmers since they represent the next generation of farming

Social revitalisation of urban regions

This paper aims to analyse how social revitalisation can contribute to an (economically) attractive urban region and how such policies can be made more effective and efficient. To stimulate re-urbanisation and attract new economic activities and residents, much attention is paid to the concept of ''the attractive city''. Cities are observed to switch their focus from hardware (tangible services) to software (image, quality of life) and orgware (organising capacity). To enhance the effectiveness of social policy is in that context often considered a spearhead for cities. In practice, social policy does not always seem to be carried out effectively. Much money may be spent on solving a problem without effective progress being accomplished. Moreover, the results of social policy are often hard to measure, so that a lack of purpose may not be easy to detect. The paper is based on a comparative research of eight European urban regions.

Neuropeptide Transmission in Brain Circuits

Neuropeptides are found in many mammalian CNS neurons where they play key roles in modulating neuronal activity. In contrast to amino acid transmitter release at the synapse, neuropeptide release is not restricted to the synaptic specialization, and after release, a neuropeptide may diffuse some distance to exert its action through a G protein-coupled receptor. Some neuropeptides such as hypocretin/orexin are synthesized only in single regions of the brain, and the neurons releasing these peptides probably have similar functional roles. Other peptides such as neuropeptide Y (NPY) are synthesized throughout the brain, and neurons that synthesize the peptide in one region have no anatomical or functional connection with NPY neurons in other brain regions. Here, I review converging data revealing a complex interaction between slow-acting neuromodulator peptides and fast-acting amino acid transmitters in the control of energy homeostasis, drug addiction, mood and motivation, sleep-wake states, and neuroendocrine regulation

Scaling-up vaccine production: implementation aspects of a biomass growth observer and controller

Abstract This study considers two aspects of the implementation of a biomass growth observer and specific growth rate controller in scale-up from small- to pilot-scale bioreactors towards a feasible bulk production process for whole-cell vaccine against whooping cough. The first is the calculation of the oxygen uptake rate, the starting point for online monitoring and control of biomass growth, taking into account the dynamics in the gas-phase. Mixing effects and delays are caused by amongst others the headspace and tubing to the analyzer. These gas phase dynamics are modelled using knowledge of the system in order to reconstruct oxygen consumption. The second aspect is to evaluate performance of the monitoring and control system with the required modifications of the oxygen consumption calculation on pilot-scale. In pilot-scale fed-batch cultivation good monitoring and control performance is obtained enabling a doubled concentration of bulk vaccine compared to standard batch productio