Albion College

About: Albion College is a education organization based out in Albion, Michigan, United States. It is known for research contribution in the topics: Population & Higher education. The organization has 485 authors who have published 754 publications receiving 20907 citations.

Restricted distribution and lateralization of mutualistic Wolbachia in the Drosophila brain.

Abstract: Microbial symbionts are universal entities of all living organisms that can significantly affect host fitness traits in manifold ways but, even more fascinating, also their behaviour. Although better known from parasitic symbionts, we currently lack any cases where 'neurotrophic' symbionts have co-evolved mutualistic behavioural interactions from which both partners profit. By theory, most mutualistic associations have originated from ancestral parasitic ones during their long-term co-evolution towards a cost-benefit equilibrium. To manipulate host behaviour in a way where both partners benefit in a reciprocal manner, the symbiont has to target and remain restricted to defined host brain regions to minimize unnecessary fitness costs. By using the classic Drosophila paulistorum model system we demonstrate that (i) mutualistic Wolbachia are restricted to various Drosophila brain areas, (ii) form bacteriocyte-like structures within the brain, (iii) exhibit strictly lateral tropism, and (iv) finally propose that their selective neuronal infection affects host sexual behaviour adaptively.

On Predicting Nucleation of Microcracks Due to Slip-Twin Interactions at Grain Boundaries in Duplex Near γ-TiAl

Abstract: Simkin et al. (2003, "A Factor to Predict Microcrack Nucleation at Gamma-Gamma Grain Boundaries in TiAl," Scr. Mater., 49(2), 149-154) proposed a relationship for predicting crack initiation in γ-TiAl in a scenario where a mechanical twin interacts with a grain boundary. This correlation (quantified using a fracture initiation parameter or fip) was based only on the geometry of the Burgers vectors as they are related to slip transfer across the grain boundary and the Mode I type opening force experienced by the grain boundary. Generally, a fip is a mathematical combination of factors that allow weak boundaries to be probabilistically identified in the context of a state of stress. This paper further develops this approach by considering the inclusion of the mismatch between the slip planes in the grain boundary and a parameter that accounts for the different elastic properties in adjoining grains. Also, the significance of primary twin (slip) systems versus secondary slip systems is assessed. When compared to fips that can be constructed through a variety of other combinations of nine geometrical parameters that could affect grain boundary damage nucleation, the fip obtained by multiplying Simkin's original parameter by E min /E max , the ratio of Young's modulus in the stress direction in the two grains, is best able to distinguish between cracked and intact grain boundary populations. Cracked and intact boundaries are also characterized to assess tilt and twist character and whether they are low Σ (or coincident site lattice) boundaries (using a cubic criterion). It is also shown that fips based on Σ values or the tilt and twist character of the boundary lead to an unacceptably high probability of incorrectly distinguishing between cracked and intact grain boundaries, implying that these are not critical parameters affecting crack nucleation at the grain boundary in duplex near-y TiAl. The paper closes with a discussion on how combined microscopic and crystal plasticity finite element analyses provide insights on local stress-strain relationships that can be used to evaluate a fip in the context of heterogeneous deformation in multigrain ensembles.

The New Paternalism: An Analysis of Power, State Intervention, and Autonomy

Abstract: “New paternalist” welfare programs are premised on the idea that service users lack certain capacities and require “supervisory” programs to guide them toward self-sufficiency. The author argues th...

Dialogue : Shrimp aquaculture in Thailand : A response to Vandergeest, Flaherty, and Miller

Abstract: Les AA. apportent une reponse critique a un precedent article de Vandergeest, Flaherty et Miller concernant l'aquaculture de la crevette en Thailande. Ils contestent notamment le rapport etabli entre les fermes d'aquaculture et les complexes industriels agro-alimentaires, et s'interrogent sur la pertinence de l'approche de l'ecologie politique dans ce champ de recherche