Understanding the Heavy Tailed Dynamics in Human Behavior

The recent availability of electronic datasets containing large volumes of communication data has made it possible to study human behavior on a larger scale than ever before. From this, it has been discovered that across a diverse range of data sets, the inter-event times between consecutive communication events obey heavy tailed power law dynamics. Explaining this has proved controversial, and two distinct hypotheses have emerged. The first holds that these power laws are fundamental, and arise from the mechanisms such as priority queuing that humans use to schedule tasks. The second holds that they are a statistical artifact which only occur in aggregated data when features such as circadian rhythms and burstiness are ignored. We use a large social media data set to test these hypotheses, and find that although models that incorporate circadian rhythms and burstiness do explain part of the observed heavy tails, there is residual unexplained heavy tail behavior which suggests a more fundamental cause. Based on this, we develop a new quantitative model of human behavior which improves on existing approaches, and gives insight into the mechanisms underlying human interactions.Comment: 9 pages in Physical Review E, 201

Human evaluation of Kea, an automatic keyphrasing system.

This paper describes an evaluation of the Kea automatic keyphrase extraction algorithm. Tools that automatically identify keyphrases are desirable because document keyphrases have numerous applications in digital library systems, but are costly and time consuming to manually assign. Keyphrase extraction algorithms are usually evaluated by comparison to author-specified keywords, but this methodology has several well-known shortcomings. The results presented in this paper are based on subjective evaluations of the quality and appropriateness of keyphrases by human assessors, and make a number of contributions. First, they validate previous evaluations of Kea that rely on author keywords. Second, they show Kea's performance is comparable to that of similar systems that have been evaluated by human assessors. Finally, they justify the use of author keyphrases as a performance metric by showing that authors generally choose good keywords

Alcohol warning labels: are they effective?

Australia does not currently require warning labels on alcohol products, putting Australia out of step with many other countries. Given the potential persuasive power of labels, as well as the rising social costs of alcoholism in the United States (US), government - mandated warning labels were enforced and have appeared on all alcoholic beverage containers manufactured in the US since 1989. The commencement of this warning label system reportedly brought about increased awareness of the risks of excessive alcohol use among consumers in the US. As a result, other countries have followed this lead with at least 20 other countries introducing some kind of mandated warning label, including Brazil, France, India, Portugal, South Africa, Korea, Thailand, and Zimbabwe. There are several other countries considering their introduction (e.g. United Kingdom), or with voluntary labeling in place (e.g. Japan). While Australia does not currently require warning labels on alcohol products, both public health advocates and the alcohol industry are pushing for labels, although it is likely they have different motivations. Medical and advocacy organisations have been campaigning for mandatory (and government regulated) warning labels on alcohol for over a decade. Key advocacy groups include the Foundation for Alcohol Research and Education (FARE), Australian Medical Associa tion (AMA), Salvation Army, and national and state Cancer Councils. These groups are consistent in their calls for strong, specific and mandatory messages on warning labels such as ‘Alcohol can cause brain damage’ (Salvation Army)

ATCA HI Observations of the NGC 6845 Galaxy Group

We present the results of ATCA HI line and 20-cm radio continuum observations of the galaxy Quartet NGC 6845. The HI emission extends over all four galaxies but can only be associated clearly with the two spiral galaxies, NGC 6845A and B, which show signs of strong tidal interaction. We derive a total HI mass of at least 1.8 x 10^10 Msun, most of which is associated with NGC 6845A, the largest galaxy of the group. We investigate the tidal interaction between NGC 6845A and B by studying the kinematics of distinct HI components and their relation to the known HII regions. No HI emission is detected from the two lenticular galaxies, NGC 6845C and D. A previously uncatalogued dwarf galaxy, ATCA J2001-4659, was detected 4.4' NE from NGC 6845B and has an HI mass of about 5 x 10^8 Msun. No HI bridge is visible between the group and its newly detected companion. Extended 20-cm radio continuum emission is detected in NGC 6845A and B as well as in the tidal bridge between the two galaxies. We derive star formation rates of 15 to 40 Msun/yr.Comment: accepted, to be published in MNRAS, for more details and the full ps-file see http://www.atnf.csiro.au/people/bkoribal/ngc684

Consequence for Wavefunction Collapse Model of the Sudbury Neutrino Observatory Experiment

It is shown that data on the dissociation rate of deuterium obtained in an experiment at the Sudbury Neutrino Observatory provides evidence that the Continuous Spontaneous Localization wavefunction collapse model should have mass--proportional coupling to be viable.Comment: 8 page

Interactive document summarisation.

This paper describes the Interactive Document Summariser (IDS), a dynamic document summarisation system, which can help users of digital libraries to access on-line documents more effectively. IDS provides dynamic control over summary characteristics, such as length and topic focus, so that changes made by the user are instantly reflected in an on-screen summary. A range of 'summary-in-context' views support seamless transitions between summaries and their source documents. IDS creates summaries by extracting keyphrases from a document with the Kea system, scoring sentences according to the keyphrases that they contain, and then extracting the highest scoring sentences. We report an evaluation of IDS summaries, in which human assessors identified suitable summary sentences in source documents, against which IDS summaries were judged. We found that IDS summaries were better than baseline summaries, and identify the characteristics of Kea keyphrases that lead to the best summaries

Prior in vitro exposure to voriconazole confers resistance to amphotericin B in aspergillus fumigatus biofilms

Triazoles are the mainstay of treatment for aspergillosis, although resistance to these antifungal agents may be associated with treatment failure. Refractory infections often necessitate a switch to other antifungal agents, including amphotericin B (AmB), although these infections may not resolve. The aim of this study was to investigate the effect of prior azole exposure on AmB sensitivity in Aspergillus fumigatus biofilms. It was hypothesised that sequential antifungal therapy has the potential to impact adaptive resistance mechanisms. Antifungal sensitivity was determined for each isolate against AmB ± voriconazole (VRZ) exposure by a broth microdilution method and an XTT metabolic assay. To analyse the role of extracellular DNA (eDNA) and Hsp90 activation, sensitivity to AmB ± DNA-digesting enzyme (DNase) or Hsp90 inhibitor [geldanamycin (GDA)] was also tested. Finally, scanning electron microscopy was performed to assess phenotypic changes. The in vitro data revealed that A. fumigatus sensitivity to AmB was decreased when it was tested in combination with VRZ. In addition, a two- to four-fold decreased sensitivity to AmB was recorded against VRZ-exposed germlings compared with controls. It was also shown that depletion of eDNA by DNase treatment enhanced AmB activity against VRZ-exposed cells by eight-fold, which visually could be explained by destabilisation of the biofilm when examined microscopically. Pharmacological inhibition of Hsp90 by GDA significantly improved biofilm susceptibility to AmB by four- to eight-fold. In conclusion, A. fumigatus pre-exposure to VRZ concomitantly induces eDNA release and activates the stress response, which collectively confers AmB resistance in vitro

Shape memory alloy actuators for active disassembly using ‘smart’ materials of consumer electronic products

This paper reports the preliminary to current development of Shape Memory Alloy (SMA) actuators within their application in ‘Active Disassembly using Smart Materials’ (ADSM). This non-destructive self-dismantling process is to aid recycling of consumer electronic products. Actuators were placed in single and multi-stage hierarchical temperature regimes after being embedded into macro and sub-assemblies of electronic product assemblies. Findings include active disassembly and a hierarchical dismantling regime for product dismantling using developed SMA actuators embedded into candidate products