The Thiol-Rich Interlayer in the Shell/Core Architecture of Mussel Byssal Threads.

The mussel byssus thread is an extremely tough core-shelled fiber that dissipates substantial amounts of energy during tensile loading. The mechanical performance of the shell is critically reliant on 3,4-dihydroxyphenylalanine's (Dopa) ability to form reversible iron-catecholate complexes at pH 8. However, the formation of these coordinate cross-links is undercut by Dopa's oxidation to Dopa-quinone, a spontaneous process at seawater conditions. The large mechanical mismatch between the cuticle and the core lends itself to further complications. Despite these challenges, the mussel byssus thread performs its tethering function over long periods of time. Here, we address these two major questions: (1) how does the mussel slow/prevent oxidation in the cuticle, and (2) how is the mechanical mismatch at the core/shell interface mitigated? By combining a number of microscopy and spectroscopy techniques we have discerned a previously undescribed layer. Our results indicate this interlayer is thiol rich and thus will be called the thiol-rich interlayer (TRL). We propose the TRL serves as a long-lasting redox reservoir as well as a mechanical barrier

The settlers of Portuguese Africa under the colonial regime and their displacement to Brazil in the post-independence period

Thousands of Portuguese rural workers came to establish themselves in Brazil leaving Africa after the destruction of the Portuguese Empire in 1975. Also came to this country white people, born in Africa as well and called "old colonists" because they were associated with the Portuguese colonizers by the anti-colonizers, although they mostly considered themselves as Africans. In fact, most of them were articulated with the interests of Portugal, though many others were more connected to black and mestizos nationalists. These ones were defined also as the African category of "sons of earth", oriented to the cause of independence of the colonies. This paper analyses the fundamental political, ideological and identity tensions - individual and collective tensions - that emerged among "old colonists" and "new comers" since their life during colonial situation until their arrival in this country of adoption, Brazil.Milhares foram os colonos portugueses que passaram pela África e vieram viver no Brasil após a derrocada do império português, em 1975. Também vieram viver neste país os brancos nascidos no continente africano, chamados de "velhos colonos", associados pelos anti-colonialistas aos portugueses, embora em grande parte se considerassem africanos. Muitos deles de fato se articularam com os interesses da metrópole, apesar de muitos outros se associassem aos nacionalistas negros e mestiços, definindo-se também com a categoria africana de "filhos da terra", orientados para a causa das independências das colônias. Este artigo aborda as tensões político-ideológicas e identitárias individuais e coletivas fundamentais que se processaram entre os "velhos colonos" e os "recém-chegados" desde sua vivência no âmbito da situação colonial até a sua chegada a este país de acolhimento, o Brasil

A comparison of US and Scotland youth soccer coaches' legal consciousness regarding concussion safety regulations

Due to the severe health consequences of sport related concussion (SRC), governments and sport governing bodies around the world have enacted numerous measures including changes to legislation and rules of the game, and increased emphasis on coach education. This study compared the legal consciousness of girls’ youth soccer coaches regarding concussion management under a statutory legal regime in the U.S. and a non-statutory regime in Scotland. The present study collected qualitative data through ten interviews of girls’ youth soccer coaches in Scotland and another ten interviews of girls’ high school soccer coaches in the U.S. Utilizing the socio-legal theory of legal consciousness, the findings support the idea that people make connections from their past experiences to shape their understanding of the law. We observed variance between U.S. and Scottish coaches’ legal consciousness. Overall, all coaches exhibited a version of conformity to and engagement with SRC management guidance and little resistance. Florida coaches displayed more conformity, likely due to the SRC educated mandated by law. Scottish coaches who had coached in the U.S. previously demonstrated the strongest resistance. The findings suggest a need for continued improvement in the implementation of SRC laws and guidelines including updated training and better dissemination of educational materials

Deadline-aware fair scheduling for multi-tenant crowd-powered systems

Crowdsourcing has become an integral part of many systems and services that deliver high-quality results for complex tasks such as data linkage, schema matching, and content annotation. A standard function of such crowd-powered systems is to publish a batch of tasks on a crowdsourcing platform automatically and to collect the results once the workers complete them. Currently, these systems provide limited guarantees over the execution time, which is problematic for many applications. Timely completion may even be impossible to guarantee due to factors specific to the crowdsourcing platform, such as the availability of workers and concurrent tasks. In our previous work, we presented the architecture of a crowd-powered system that reshapes the interaction mechanism with the crowd. Specifically, we studied a push-crowdsourcing model whereby the workers receive tasks instead of selecting them from a portal. Based on this interaction model, we employed scheduling techniques similar to those found in distributed computing infrastructures to automate the task assignment process. In this work, we first devise a generic scheduling strategy that supports both fairness and deadline-awareness. Second, to complement the proof-of-concept experiments previously performed with the crowd, we present an extensive set of simulations meant to analyze the properties of the proposed scheduling algorithms in an environment with thousands of workers and tasks. Our experimental results show that, by accounting for human factors, micro-task scheduling can achieve fairness for best-effort batches and boosts production batches

Changes in reflectin protein phosphorylation are associated with dynamic iridescence in squid

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of The Royal Society for personal use, not for redistribution. The definitive version was published in Journal of The Royal Society Interface 6 (2010): 549-560, doi:10.1098/rsif.2009.0299.Many cephalopods exhibit remarkable dermal iridescence, a component of their complex, dynamic camouflage and communication. In the species Euprymna scolopes, the light-organ iridescence is static and is due to reflectin protein-based platelets assembled into lamellar thin-film reflectors called iridosomes, contained within iridescent cells called iridocytes. Squid in the family Loliginidae appear to be unique in that the dermis possesses a dynamic iridescent component, with reflective, colored structures that are assembled and disassembled under the control of the muscarinic cholinergic system and the associated neurotransmitter acetylcholine (Mathger et al. 2004). Here we present the sequences and characterization of three new members of the reflectin family associated with the dynamically changeable iridescence in Loligo and not found in static Euprymna iridophores. In addition, we show that application of genistein, a protein tyrosine kinase inhibitor, suppresses acetylcholine- and calcium-induced iridescence in Loligo. We further demonstrate that two of these novel reflectins are extensively phosphorylated in concert with the activation of iridescence by exogenous acetylcholine. This phosphorylation and the correlated iridescence can be blocked with genistein. Our results suggest that tyrosine phosphorylation of reflectin proteins is involved in the regulation of dynamic iridescence in Loligo.We gratefully acknowledge support from Anteon contract F33615-03-D-5408 to the Marine Biological Laboratory, Woods Hole, MA and grant # W911NF-06-1-0285 from the Army Research Office to D.E.M