Scalable eventually consistent counters over unreliable networks

Counters are an important abstraction in distributed computing, and play a central role in large scale geo-replicated systems, counting events such as web page impressions or social network “likes”. Classic distributed counters, strongly consistent via linearisability or sequential consistency, cannot be made both available and partition-tolerant, due to the CAP Theorem, being unsuitable to large scale scenarios. This paper defines Eventually Consistent Distributed Counters (ECDCs) and presents an implementation of the concept, Handoff Counters, that is scalable and works over unreliable networks. By giving up the total operation ordering in classic distributed counters, ECDC implementations can be made AP in the CAP design space, while retaining the essence of counting. Handoff Counters are the first Conflict-free Replicated Data Type (CRDT) based mechanism that overcomes the identity explosion problem in naive CRDTs, such as G-Counters (where state size is linear in the number of independent actors that ever incremented the counter), by managing identities towards avoiding global propagation and garbage collecting temporary entries. The approach used in Handoff Counters is not restricted to counters, being more generally applicable to other data types with associative and commutative operations.This work was partially supported by SMILES within project “TEC4Growth Pervasive Intelligence, Enhancers and Proofs of Concept with Industrial Impact/NORTE-01- 0145-FEDER-000020” financed by the North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, and through the European Regional Development Fund (ERDF); EU FP7 SyncFree project (609551), and EU H2020 LightKone project (732505).info:eu-repo/semantics/publishedVersio

Important Teacher Qualities for Integrating Blended Learning in Higher Education

Blended learning is widely accepted in Peruvian higher education for a number of reasons, including the fact that it allows students more leeway to accommodate their own unique schedule and learning needs. The present qualitative research investigates the qualities of effective teachers that are crucial to the successful implementation of blended learning from the vantage point of experts, who can gain valuable insight into the causes of organizational problems and the best strategies for resolving them. There are seven positive characteristics of blended learning teachers, such as the ability to recognize the need for pedagogical change or the confidence to incorporate technology into learning processes, and four negative characteristics, such as a lack of familiarity with blended learning or anxiety about students use of technology. Blended learning in higher education is investigated here to identify the factors that influence it

Improvement in Water Stability and Other Related Functional Properties of Thin Cast Kafirin Protein Films

Improvement in the water stability and other related functional properties of thin (<50 µm) karirin protein films was investigated. Thin conventional kafirin films and kafirin microparticle films were prepared by casting in acetic acid solution. Thin kafirin films cast from microparticles were more stable in water than conventional cast kafirin films. Treatment of kafirin microparticles with heat and transglutaminase resulted in slightly thicker films with reduced tensile strength. In contrast, glutaraldehyde treatment resulted in up to a 43% increase in film tensile strength. The films prepared from microparticles treated with glutaraldehyde treatment were quite stable in ambient temperature water, despite the loss of plasticizer. This was probably due to the formation of convalent crosslinking between free amino groups if the kafirin polypeptides and carbonyl groups of the aldehyde. Thus, such thin glutaraldehyde-treated kafirin microparticle films appear to have good potential for use as biomaterials in aqueous applications.J.O.A. acknowledges a University of Pretoria Postgraduate Research Support Bursary.http://pubs.acs.org/JAF