Exotic Rickettsiae in Ixodes ricinus: fact or artifact?

Several pathogenic Rickettsia species can be transmitted via Ixodes ricinus ticks to humans and animals. Surveys of I. ricinus for the presence of Rickettsiae using part of its 16S rRNA gene yield a plethora of new and different Rickettsia sequences. Interpreting these data is sometimes difficult and presenting these findings as new or potentially pathogenic Rickettsiae should be done with caution: a recent report suggested presence of a known human pathogen, R. australis, in questing I. ricinus ticks in Europe. A refined analysis of these results revealed that R. helvetica was most likely to be misinterpreted as R. australis. Evidence in the literature is accumulating that rickettsial DNA sequences found in tick lysates can also be derived from other sources than viable, pathogenic Rickettsiae. For example, from endosymbionts, environmental contamination or even horizontal gene transfer

The Transnational Political Economy of Corporate Governance Regulation: A Research Outline

Corporate governance has become a buzzword of the global business community and is now receiving even wider attention given the repercussions of the Enron collapse. Although there is a burgeoning literature on this topic, the bulk of it is either highly normative or focused on corporate governance practices at the level of the firm. In contrast, our aim is to explain the current transformations of corporate governance regulation. Whereas this regulation used to be a distinctly national affair, it is now increasingly an area subject to both public and private (self-) regulation in multiple arenas, of which three are outstandingly important as well as closely interrelated and, therefore, form the empirical focus of the programme:- Europeanisation in the area of corporate governance regulation affects national regimes of corporate governance with a particular historical diversity, without entirely replacing them.- The EU, furthermore, does not operate in a vacuum but in a transatlantic and global context where it has to negotiate its choices with both state (mainly the US) and non-state actors. At the global level, private bodies such as the International Accounting Standards Board set many corporate governance standards, and international organisations like the OECD disseminate norms for good corporate governance.- Central and East European countries (CEEC) are exposed to the multiple (and partially conflicting) demands by global institutions and the EU when developing their corporat

Where the linearized Poisson-Boltzmann cell model fails: (I) spurious phase separation in charged colloidal suspensions

We perform a linearization of the Poisson-Boltzmann (PB) density functional for spherical Wigner-Seitz cells that yields Debye-H\"uckel-like equations agreeing asymptotically with the PB results in the weak-coupling (high-temperature) limit. Both the canonical (fixed number of microions) as well as the semi-grand-canonical (in contact with an infinite salt reservoir) cases are considered and discussed in a unified linearized framework. In the canonical case, for sufficiently large colloidal charges the linearized theory predicts the occurrence of a thermodynamical instability with an associated phase separation of the homogeneous suspension into dilute (gas) and dense (liquid) phases. In the semi-grand-canonical case it is predicted that the isothermal compressibility and the osmotic-pressure difference between the colloidal suspension and the salt reservoir become negative in the low-temperature, high-surface charge or infinite-dilution (of polyions) limits. As already pointed out in the literature for the latter case, these features are in disagreement with the exact nonlinear PB solution inside a Wigner-Seitz cell and are thus artifacts of the linearization. By using explicitly gauge-invariant forms of the electrostatic potential we show that these artifacts, although thermodynamically consistent with quadratic expansions of the nonlinear functional and osmotic pressure, may be traced back to the non-fulfillment of the underlying assumptions of the linearization.Comment: 32 pages, 3 PostScript figures, submitted to J. Chem. Phy

Parenting in times of war: A meta-analysis and qualitative synthesis of war-exposure, parenting, and child adjustment

This mixed-methods systematic review and meta-analysis sheds more light on the role parenting practices play in children’s adjustment after war exposure. Specifically, we quantitatively examined how war exposure shapes parenting behavior, and whether parenting behavior explains some of the well-known associations between war exposure and children’s adjustment. In addition, we meta-synthesized the qualitative evidence answering when and why parenting practices might change for war-affected families. We searched nine electronic databases and contacted experts in the field for relevant studies published until March 2018, identifying 4,147 unique publications that were further screened by title and abstract, resulting in 158 publications being fully screened. By running a meta-analytic structural equation model (MASEM) with 38 quantitative studies (N = 54,372, Mage = 12.00, SDage = 3.54), we found that war-exposed parents showed less warmth and more harshness towards their children, which partly mediated the association between war exposure and child adjustment, i.e., more post-traumatic stress symptoms, depression and anxiety, social problems, externalizing behavior, and lower positive outcomes. War exposure was not associated with parents’ exercise of behavioral control. Through meta-synthesizing ten qualitative studies (N = 1,042, age range = 0-18), we found that the nature of war-related trauma affected parenting differently. That is, parents showed harshness, hostility, inconsistency and less warmth in highly dangerous settings, and more warmth and overprotection when only living under threat. We conclude that it is not only how much but also what families have seen that shape parenting in times of war

Many-body interactions and melting of colloidal crystals

We study the melting behavior of charged colloidal crystals, using a simulation technique that combines a continuous mean-field Poisson-Boltzmann description for the microscopic electrolyte ions with a Brownian-dynamics simulation for the mesoscopic colloids. This technique ensures that many-body interactions between the colloids are fully taken into account, and thus allows us to investigate how many-body interactions affect the solid-liquid phase behavior of charged colloids. Using the Lindemann criterion, we determine the melting line in a phase-diagram spanned by the colloidal charge and the salt concentration. We compare our results to predictions based on the established description of colloidal suspensions in terms of pairwise additive Yukawa potentials, and find good agreement at high-salt, but not at low-salt concentration. Analyzing the effective pair-interaction between two colloids in a crystalline environment, we demonstrate that the difference in the melting behavior observed at low salt is due to many-body interactions