Polymer adsorption on heterogeneous surfaces

The adsorption of a single ideal polymer chain on energetically heterogeneous and rough surfaces is investigated using a variational procedure introduced by Garel and Orland (Phys. Rev. B 55 (1997), 226). The mean polymer size is calculated perpendicular and parallel to the surface and is compared to the Gaussian conformation and to the results for polymers at flat and energetically homogeneous surfaces. The disorder-induced enhancement of adsorption is confirmed and is shown to be much more significant for a heterogeneous interaction strength than for spatial roughness. This difference also applies to the localization transition, where the polymer size becomes independent of the chain length. The localization criterion can be quantified, depending on an effective interaction strength and the length of the polymer chain.Comment: accepted in EPJB (the Journal formerly known as Journal de Physique

Forces between Colloidal Particles in Aqueous Solutions Containing Monovalent and Multivalent Ions

The present article provides an overview of the recent progress in the direct force measurements between individual pairs of colloidal particles in aqueous salt solutions. Results obtained by two different techniques are being highlighted, namely with the atomic force microscope (AFM) and optical tweezers. One finds that the classical theory of Derjaguin, Landau, Verwey, and Overbeek (DLVO) represents an accurate description of the force profiles even in the presence of multivalent ions, typically down to distances of few nanometers. However, the corresponding Hamaker constants and diffuse layer potentials must be extracted from the force profiles. At low salt concentrations, double layer forces remain repulsive and may become long ranged. At short distances, additional short range non-DLVO interactions may become important. Such an interaction is particularly relevant in the presence of multivalent counterions.Comment: Submitted on 30th of May 2016 as invited article to Curr. Opinion Colloid Interf. Sci. Edited by W. Ducker and P. Claesson. 15 Pages, 7 Figures 82 reference

Implementing US-style anti-fraud laws in the Australian pharmaceutical and health care industries

This article critically analyses the prospects for introducing United States anti-fraud (or anti-false claims) laws in the Australian health care setting. Australian governments spend billions of dollars each year on medicines and health care. A recent report estimates that the money lost to corporate fraud in Australia is growing at an annual rate of 7%, but that only a third of the losses are currently being detected. In the US, qui tam provisions - the component of anti-fraud or anti-false claims laws involving payments to whistleblowers - have been particularly successful in providing critical evidence allowing public prosecutors to recover damages for fraud and false claims made by corporations in relation to federal and state health care programs. The US continues to strengthen such anti-fraud measures and to successfully apply them to a widening range of areas involving large public investment. Australia still suffers from the absence of any comprehensive scheme that not only allows treble damages recovery for fraud on the public purse, but crucially supports such actions by providing financial encouragement for whistleblowing corporate insiders to expose evidence of fraud. Potential areas of application could include direct and indirect government expenditure on health care service provision, pharmaceuticals, medical devices, defence, carbon emissions compensation and tobacco-related illness. The creation in Australia of an equivalent to US anti-false claims legislation should be a policy priority, particularly in a period of financial stringency

The Bohm sheath criterion in strongly coupled complex plasmas

A modification of the classical Bohm sheath criterion is investigated in complex plasmas containing Boltzmann electrons, cold fluid ions and strongly coupled microparticles. Equilibrium is provided by an effective 'temperature' associated with electrostatic interactions between charged grains. Using the small-potential expansion approach of the Sagdeev potential, a significant reduction of the ion Bohm velocity is obtained for complex plasma parameters relevant for experiments. The result is of consequence for all problems involving ion drag on microparticles, including parametric instability, structure formation, wave propagation, etc

Robust Optimal Risk Sharing and Risk Premia in Expanding Pools

We consider the problem of optimal risk sharing in a pool of cooperative agents. We analyze the asymptotic behavior of the certainty equivalents and risk premia associated with the Pareto optimal risk sharing contract as the pool expands. We first study this problem under expected utility preferences with an objectively or subjectively given probabilistic model. Next, we develop a robust approach by explicitly taking uncertainty about the probabilistic model (ambiguity) into account. The resulting robust certainty equivalents and risk premia compound risk and ambiguity aversion. We provide explicit results on their limits and rates of convergence, induced by Pareto optimal risk sharing in expanding pools

Remarques sur le groupe de Carex muricata en Hesse

Als Ergebnis einer Herbarrevision kann die Verbreitung der Carexmuricata-Gruppe in Hessen wie folgt charakterisiert werden: Carex spicata ist in Säumen und Grünland der Ortsbereiche weit verbreitet. Carex muricata ist eine weitverbreitete Saumart in Wäldern auf basen-, insbesondere kalkreichen Böden. Carex polyphylla hat eine ähnliche Verbreitung, kommt aber auch in schwach gestörten, teilweise ruderalisierten Saumstandorten vor. Carex pairae scheint auf Saumstandorte in Wäldern basenarmer Standorte Südhessens beschränkt zu sein. Carex divulsa ist die seltenste Art. Bisher liegen Funde aus Südhessen und dem Odenwald und sehr isoliert aus dem Schwalm-Eder-Kreis vor. Literaturangaben zum Vorkommen der Carex-muricata-Gruppe in Hessen sind kaum brauchbar. Der Mehrzahl der Herbarbelege war falsch bestimmt.A revision of herbarium specimens was used to characterise the distribution of the Carex muricata group in Hesse. C. spicata is widespread in marginal and grassland habitats of populated areas. C. muricata and C. polyphylla are widespread in base-rich habitats of forest margins. The latter species is the more common of the two and also occurs in mildly disturbed margins of wasteland habitats. C. pairae appears to be restricted mainly to base-poor habitats of forest margins in southern Hesse. C. divulsa is the rarest species, with records from southern Hesse and the Odenwald region, and an isolated record from the Schwalm-Eder region. Literature records for all taxa are often erroneous. The majority of herbarium specimens had to be revised.D’après les conclusions tirées d’une révision des spécimens d’herbier, la répartition du groupe Carex muricata dans la Hesse peut être caractérisée ainsi : Carex spicata se trouve largement répandue en ourlets et sur les parties verdoyantes des sites. Carex muricata se trouve largement répandue en ourlets sur des sols basiques et surtout riches en calcaire. Carex polyphylla a une répartition semblable mais elle se trouve également en ourlets sur des sites peu perturbés et modérément ruderalisés. Carex pairae parait se limiter aux ourlets des forêts aux sols pauvres en bases du sud de la Hesse. Carex divulsa est l’espèce la plus rare. A ce jour n’ont été découverts des spécimens que dans le sud de la Hesse et dans l’Odenwald et quelques-uns, très isolés, dans le Schwalm-Eder-Kreis. Les références dans la littérature sur la présence de Carex muricata ne sont pas exploitables. La plupart des spécimens des herbiers étaient mal identifiés