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

MAO-A and the EEG Recognition Memory Signal in Left Parietal Cortex

A key part of episodic memory, or memory for the events of our lives, is recognition memory. Recognition memory is the ability to remember previously encountered stimuli. Studies have linked recognition memory to the old/new effect, an EEG indicator of stimulus familiarity. Monoamine oxidase A (MAO-A) is an enzyme that catalyzes monoamines, leading to the depletion of norepinephrine, epinephrine, serotonin, and dopamine. MAO-A is more efficiently transcribed in individuals with a 4 repeating sequence variation (4R) of the MAO-A gene leading to less monoamine availability. As many of these monoamines have been linked to episodic memory, we hypothesized that individuals homozygous for the 4R MAO-A polymorphism would show differences in mean EEG signal amplitudes during recognition memory. EEG data was recorded as participants viewed both new words and words that had been previously presented. Our results show that mean peak amplitudes over the left parietal cortex 500-800 ms post-stimulus presentation for hits were greater than those for correct rejections, indicating the old/new effect. Critically, our results revealed an interaction between mean hit and correct rejection amplitude over the left parietal cortex and MAO-A group. Individuals homozygous for the 4R variation (the High MAO-A group) do not show an old/new effect due to increased correct rejection amplitudes. These results suggest that less monoamine availability leads to new stimuli being identified as old by the left parietal cortex

The productivity of Western Australia\u27s wheat and sheep industry

A popular economic lament is that Australian industries and workers are not as productive as they should be. Politicians and economic commentators preach the need for productivity improvement and workplace reform, and criticise inefficiency and lack of endeavour. Can such criticism be fairly levelled at farmers and agricultural scientists? What is productivity and how is it measured? What is the productivity of Western Australia\u27s main agricultural industry — wheat and sheep farming? This article addresses these questions and shows that our wheat-sheep industry can be moderately proud of its productivity recor

Faculty Senate Structure: A Proposal Including Budgets

It has become increasingly difficult for the Faculty Senate, the FS President and the Operations Committee (OPS) to adequately meet all the legitimate needs and time demands of their respective roles. It is also increasingly difficult for the Faculty Senate to respond to new initiatives and weigh in proactively on strategic directives coming from the Administration, the Regents, and our wider organizational environment. If shared governance within the University is to really work well, and lead UNM in the best strategic pursuit of its academic mission in the future, we believe we simply have to havea structure that both embodies democratic practice andis capable of responding in an efficient way which is less centralized in the person of the FS President

Project Hydra: Designing & Building a Reusable Framework for Multipurpose, Multifunction, Multi-institutional Repository-Powered Solutions

4th International Conference on Open RepositoriesThis presentation was part of the session : Fedora User Group PresentationsDate: 2009-05-20 03:30 PM – 05:00 PMThere is a clear business need in higher education for a flexible, reusable application framework that can support the rapid development of multiple systems tailored to distinct needs, but powered by a common underlying repository. Recognizing this common need, Stanford University, the University of Hull and the University of Virginia are collaborating on "Project Hydra", a three-year effort to create an application and middleware framework that, in combination with an underlying Fedora repository, will create a reusable environment for running multifunction, multipurpose repository-powered solutions. This paper details the collaborators' functional and technical design for such a framework, and will demonstrate the progress made to date on the initiative.JIS

Ancestral physical stress and later immune gene family expansions shaped bivalve mollusc evolution

Bivalve molluscs comprise 20,000 species occupying a wide diversity of marine habitats. As filter feeders and detritivores they act as ecosystem engineers clarifying water, creating reefs, and protecting coastlines. The global decline of natural oyster reefs has led to increased restoration efforts in recent years. Bivalves also play an important role in global food security contributing to >20% of worldwide aquaculture production. Despite this importance, relatively little is known about bivalve evolutionary adaptation strategies. Difficulties previously associated with highly heterozygous and repetitive regions of bivalve genomes have been overcome by long-read sequencing, enabling the generation of accurate bivalve assemblies. With these resources we have analyzed the genomes of 32 species representing each molluscan class, including 15 bivalve species, to identify gene families that have undergone expansion during bivalve evolution. Gene family expansions across bivalve genomes occur at the point of evolutionary pressures. We uncovered two key factors that shape bivalve evolutionary history: expansion of bivalvia into environmental niches with high stress followed by later exposure to specific pathogenic pressures. The conserved expansion of protein recycling gene families we found across bivalvia is mirrored by adaptations to a sedentary lifestyle seen in plants. These results reflect the ability of bivalves to tolerate high levels of environmental stress and constant exposure to pathogens as filter feeders. The increasing availability of accurate genome assemblies will provide greater resolution to these analyses allowing further points of evolutionary pressure to become clear in other understudied taxa and potentially different populations of a single species