Particles at oil–air surfaces : powdered oil, liquid oil marbles, and oil foam

The type of material stabilized by four kinds of fluorinated particles (sericite and bentonite platelet clays and spherical zinc oxide) in air–oil mixtures has been investigated. It depends on the particle wettability and the degree of shear. Upon vigorous agitation, oil dispersions are formed in all the oils containing relatively large bentonite particles and in oils of relatively low surface tension (γla < 26 mN m⁻¹) like dodecane, 20 cS silicone, and cyclomethicone containing the other fluorinated particles. Particle-stabilized oil foams were obtained in oils having γla > 26 mN m⁻¹ where the advancing air–oil–solid contact angle θ lies between ca. 90° and 120°. Gentle shaking, however, gives oil-in-air liquid marbles with all the oil–particle systems except for cases where θ is <60°. For oils of tension >24 mN m⁻¹ with omniphobic zinc oxide and sericite particles for which advancing θ ≥ 90°, dry oil powders consisting of oil drops in air which do not leak oil could be made upon gentle agitation up to a critical oil:particle ratio (COPR). Above the COPR, catastrophic phase inversion of the dry oil powders to air-in-oil foams was observed. When sheared on a substrate, the dry oil powders containing at least 60 wt % of oil release the encapsulated oil, making these materials attractive formulations in the cosmetic and food industries

Impact of the structural integrity of the three-way junction of adenovirus VAI RNA on PKR inhibition

Sherpa Romeo green journal. Open access article. Creative Commons Attribution License applies.Highly structured RNA derived from viral genomes is a key cellular indicator of viral infection. In response, cells produce the interferon inducible RNA-dependent protein kinase (PKR) that, when bound to viral dsRNA, phosphorylates eukaryotic initiation factor 2αand attenuates viral protein translation. Adenovirus can evade this line of defence through transcription of a non-coding RNA, VAI, an inhibitor of PKR. VAI consists of three base-paired regions that meet at a three-way junction; an apical stem responsible for the interaction with PKR, a central stem required for inhibition, and a terminal stem. Recent studies have highlighted the potential importance of the tertiary structure of the three-way junction to PKR inhibition by enabling interaction between regions of the central and terminal stems. To further investigate the role of the three-way junction, we characterized the binding affinity and inhibitory potential of central stem mutants designed to introduce subtle alterations. These results were then correlated with small-angle X-ray scattering solution studies and computational tertiary structural models. Our results demonstrate that while mutations to the central stem have no observable effect on binding affinity to PKR, mutations that appear to disrupt the structure of the three-way junction prevent inhibition of PKR. Therefore, we propose that instead of simply sequestering PKR, a specific structural conformation of the PKR-VAI complex may be required for inhibition

Activation of 2′ 5′-oligoadenylate synthetase by stem loops at the 5′-end of the West Nile virus genome

West Nile virus (WNV) has a positive sense RNA genome with conserved structural elements in the 5′ and 3′ -untranslated regions required for polyprotein production. Antiviral immunity to WNV is partially mediated through the production of a cluster of proteins known as the interferon stimulated genes (ISGs). The 2′ 5′-oligoadenylate synthetases (OAS) are key ISGs that help to amplify the innate immune response. Upon interaction with viral double stranded RNA, OAS enzymes become activated and enable the host cell to restrict viral propagation. Studies have linked mutations in the OAS1 gene to increased susceptibility to WNV infection, highlighting the importance of OAS1 enzyme. Here we report that the region at the 5′-end of the WNV genome comprising both the 5′-UTR and initial coding region is capable of OAS1 activation in vitro. This region contains three RNA stem loops (SLI, SLII, and SLIII) whose relative contribution to OAS1 binding affinity and activation were investigated using electrophoretic mobility shift assays and enzyme kinetics experiments. Stem loop I, comprising nucleotides 1-73, is dispensable for maximum OAS1 activation, as a construct containing only SLII and SLIII was capable of enzymatic activation. Mutations to the RNA binding site of OAS1 confirmed the specificity of the interaction. The purity, monodispersity and homogeneity of the 5′-end (SLI/II/III) and OAS1 were evaluated using dynamic light scattering and analytical ultra-centrifugation. Solution conformations of both the 5′-end RNA of WNV and OAS1 were then elucidated using small-angle x-ray scattering. In the context of purified components in vitro, these data demonstrate the recognition of conserved secondary structural elements of the WNV genome by a member of the interferon-mediated innate immune response

An agent for effective negotiation dialogues

Dialogue Systems: Interaction Adaptation and styles of Management workshop at the 10th Conference of the European Chapter of the Association of Computational Linguistics (EACL03), Budapest, Hungary, April 12-17, 2003A design is presented for a negotiating agent that can construct coherent joint plans with human or artificial agents. In negotiation there is always a trade-off between plan quality and dialogue length. In dynamic conditions and with human partners, length becomes critical. The approach to efficient negotiation is to use an acquaintance model that predicts which plans will be acceptable. The negotiation dialogue then consists of exchanges to construct the acquaintance model and exchanges of plan proposals.kpw12/7/1

Machine Learning for Adaptive Spoken Control in PDA Applications

Artificial Intelligence in Mobile Systems 2003 Workshop (AIMS 2003), 12th October, 2003, Seattle, USA, in conjunction with 5th International Conference on Ubiquitous ComputingA machine learning approach to interpreting utterances in spoken interfaces is described, where evidence from the utterance and from the dialogue context is combined to estimate a probability distribution over interpretations. The algorithm for the utterance evidence uses nearest-neighbour classification on a set of training examples, while the contextual evidence is provided by dialogue act n-grams derived from dialogue corpora. Each algorithm can adapt by recording data from the user at hand. Experimental results for the utterance interpreter show that adaptation to a particular user’s training utterances significantly improves recognition accuracy over training on utterances from the general population.8.7.2013 S

Efficient Dialogue Using a Probabilistic Nested User Model

The 4th IJACI Workshop on Knowledge and Reasoning in Practical Dialogue Systems, Edinburgh, Scotland, August 1, 2005We describe a set of dialogue simulation experiments, in which a probabilistic nested user model is employed in deciding between speech acts for a collaborative planning task, finding that a gain in utility can be obtained by using a probabilistic rather than a logical model. Given a set of ordinary dialogue plan rules, our system generates a gametree representation of the dialogue, using chance nodes to represent uncertain preconditions in the plan. Then, the game-tree is evaluated with respect to a given user model state.SB. 30.7.201

A planner for plan construction plans for multi-agent plans

The 15th Irish Conference on Artificial Intelligence and Cognitive Science (AICS'04), September 8th - 10th 2004, Castlebar, IrelandA natural language dialogue planner is described that chooses dialogue moves to revise the beliefs of an agent. In particular those beliefs that refer to the mental state of another agent are revised. In a planning problem of repeated decisions, the future decision of the other agent is better predicted, and therefore the immediate plan decision of the first agent is a better one1/8/1

Planning to replan in a multi-agent environment

The 23rd Workshop of the UK Planning and Scheduling Special Interest Group, December 20th - 21st 2004, Cork, IrelandA multi-agent planner is described that accounts for the replanning occurring when one agent’s action is observed by another. A nested belief model is used to generate an expectation of the other agent’s response. Using the planner’s output, a dialogue system is being developed which decides whether uncertainties in the belief model should be resolved through dialogue before execution of the domain level plankpw1/8/1

Dynamic choice of robust strategies in dialogue management

ROBUST 2004 Research Workshop on Robustness Issues in Conversational Interaction, University of East Anglia, Norwich, UK, August 30-31, 2004An important tradeoff in error-prone dialogue is between the cost of using more robust dialogue strategies and the cost of recovering from failed understanding without using them. A strategy has to be quantitatively planned for each dialogue state, since too robust a strategy might not have a worthwhile effect on the failure rate. A dialogue manager is described which chooses between strategies that have differing levels of robustness with a view to maximising the efficiency of the dialoguekpw1/8/1