Dean flow focusing and separation of small microspheres within a narrow size range.

Copyright The Author(s) 2014. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedRapid, selective particle separation and concentration within the bacterial size range (1–3 μm) in clinical or environmental samples promises significant improvements in detection of pathogenic microorganisms in areas including diagnostics and bio-defence. It has been proposed that microfluidic Dean flow-based separation might offer simple, efficient sample clean-up: separation of larger, bioassay contaminants to prepare bioassay targets including spores, viruses and proteins. However, reports are limited to focusing spherical particles with diameters of 5 μm or above. To evaluate Dean flow separation for (1–3 μm) range samples, we employ a 20 μm width and depth, spiral microchannel. We demonstrate focusing, separation and concentration of particles with closely spaced diameters of 2.1 and 3.2 μm, significantly smaller than previously reported as separated in Dean flow devices. The smallest target, represented by 1.0 μm particles, is not focused due to the high pressures associated with focussing particles of this size; however, it is cleaned of 93 % of 3.2 μm and 87 % of 2.1 μm microparticles. Concentration increases approaching 3.5 times, close to the maximum, were obtained for 3.2 μm particles at a flow rate of 10 μl min−1. Increasing concentration degraded separation, commencing at significantly lower concentrations than previously predicted, particularly for particles on the limit of being focused. It was demonstrated that flow separation specificity can be fine-tuned by adjustment of output pressure differentials, improving separation of closely spaced particle sizes. We conclude that Dean flow separation techniques can be effectively applied to sample clean-up within this significant microorganism size range.Peer reviewedFinal Published versio

For Sale: Analysis of exclusion of people from land in Melanesia and directions forward

A two-day “publication workshop” was convened by SSGM/ANU and Oxfam Australia as part of the Australian Association for Pacific Studies (AAPS) biennial conference held at Sydney University. The workshop brought together policymakers, academics, NGOs and activists with a shared interest in contemporary land issues in post-colonial Melanesia. It was chaired by Mr Ralph Regenvanu, Vanuatu Minister for Lands and Natural Resources, and involved a number of other distinguished guest participants including Mr Charles Lepani, High Commissioner for Papua New Guinea, Dr James Weiner (ANU) and professors George Curry (Curtin University), John Connell (University of Sydney) and Margaret Jolly (ANU). Highlights The eleven papers and one interview that were presented at the workshop were empirically and theoretically rich, and, though diverse in terms of topics and approaches, there were a number of theoretical and thematic threads that wove them together into an intellectually coherent set (see below). Collectively the papers presented provide a unique set of perspectives on land issues in Melanesia, including from Melanesian researchers and a significant number of women researchers. Many of the authors had not previously written about land and offered their unique „voices‟ as part of the larger international debate. Some of the empirics that were presented were especially striking, for example that the region‟s urban settlements are growing at an average rate of 7 per cent per annum and that 12 per cent of PNG‟s land area has come under Special Agricultural and Business Leases (SABLs) since 1995. The stories told of the recent “ministerial land grab” in Vanuatu, PNG‟s SABL saga, and the contemporary political economy of land allocation in Honiara were particularly sobering. However, these were tempered by more positive stories, for example, the recent passage of a major land reform programme in Vanuatu, that gave cause for optimism. The diverse array of actors that animated these stories was also striking: from the cleaners and drivers in the Vanuatu Lands Department who had been gifted land titles by the previous Minister, to shady “Asian businessmen” and globalised oil palm corporations. Collectively the workshop participants were challenged, by Minister Regenvanu and other participants from the region, to ensure that the research findings are communicated effectively and made available to those who have the most potential to be empowered by them. Charles Lepani also pointed to the importance of developing collaborative research partnerships between foreign researchers and Pacific Islander researchers and policy-makers. One highlight of the first day was Charles Lepani‟s reading aloud of a text message from the Prime Minister of PNG, Peter O‟Neill, which announced publically for the first time that SABL‟s “that have been abused for forestry” will be cancelled or suspended and that cabinet approval will be required for leases over “large parcels of land” (reported by Radio Australia here).AusAI

Methods for Generating Complex Networks with Selected Structural Properties for Simulations: A Review and Tutorial for Neuroscientists

Many simulations of networks in computational neuroscience assume completely homogenous random networks of the Erdös–Rényi type, or regular networks, despite it being recognized for some time that anatomical brain networks are more complex in their connectivity and can, for example, exhibit the “scale-free” and “small-world” properties. We review the most well known algorithms for constructing networks with given non-homogeneous statistical properties and provide simple pseudo-code for reproducing such networks in software simulations. We also review some useful mathematical results and approximations associated with the statistics that describe these network models, including degree distribution, average path length, and clustering coefficient. We demonstrate how such results can be used as partial verification and validation of implementations. Finally, we discuss a sometimes overlooked modeling choice that can be crucially important for the properties of simulated networks: that of network directedness. The most well known network algorithms produce undirected networks, and we emphasize this point by highlighting how simple adaptations can instead produce directed networks

Evaluating Amazon\u27s Mechanical Turk as a Tool for Experimental Behavioral Research

Amazon Mechanical Turk (AMT) is an online crowdsourcing service where anonymous online workers complete web-based tasks for small sums of money. The service has attracted attention from experimental psychologists interested in gathering human subject data more efficiently. However, relative to traditional laboratory studies, many aspects of the testing environment are not under the experimenter\u27s control. In this paper, we attempt to empirically evaluate the fidelity of the AMT system for use in cognitive behavioral experiments. These types of experiment differ from simple surveys in that they require multiple trials, sustained attention from participants, comprehension of complex instructions, and millisecond accuracy for response recording and stimulus presentation. We replicate a diverse body of tasks from experimental psychology including the Stroop, Switching, Flanker, Simon, Posner Cuing, attentional blink, subliminal priming, and category learning tasks using participants recruited using AMT. While most of replications were qualitatively successful and validated the approach of collecting data anonymously online using a web-browser, others revealed disparity between laboratory results and online results. A number of important lessons were encountered in the process of conducting these replications that should be of value to other researchers

Evaluation ofthe Middle East and North Africa Land Data Assimilation System

The Middle East and North Africa (MENA) region is dominated by dry, warm deserts, areas of dense population, and inefficient use of fresh water resources. Due to the scarcity, high intensity, and short duration of rainfall in the MENA, the region is prone to hydro climatic extremes that are realized by devastating floods and times of drought. However, given its widespread water stress and the considerable demand for water, the MENA remains relatively poorly monitored. This is due in part to the shortage of meteorological observations and the lack of data sharing between nations. As a result, the accurate monitoring of the dynamics of the water cycle in the MENA is difficult. The Land Data Assimilation System for the MENA region (MENA LDAS) has been developed to provide regional, gridded fields of hydrological states and fluxes relevant for water resources assessments. As an extension of the Global Land Data Assimilation System (GLDAS), the MENA LDAS was designed to aid in the identification and evaluation of regional hydrological anomalies by synergistically combining the physically-based Catchment Land Surface Model (CLSM) with observations from several independent data products including soil-water storage variations from the Gravity Recovery and Climate Experiment (GRACE) and irrigation intensity derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). In this fashion, we estimate the mean and seasonal cycle of the water budget components across the MENA

Towards a transformative understanding of the ocean’s biological pump: Priorities for future research - Report on the NSF Biology of the Biological Pump Workshop

NSF Biology of the Biological Pump Workshop, February 19–20, 2016 (Hyatt Place New Orleans, New Orleans, LA)The net transfer of organic matter from the surface to the deep ocean is a key function of ocean food webs. The combination of biological, physical, and chemical processes that contribute to and control this export is collectively known as the “biological pump”, and current estimates of the global magnitude of this export range from 5 – 12 Pg C yr-1. This material can be exported in dissolved or particulate form, and many of the biological processes that regulate the composition, quantity, timing, and distribution of this export are poorly understood or constrained. Export of organic material is of fundamental importance to the biological and chemical functioning of the ocean, supporting deep ocean food webs and controlling the vertical and horizontal segregation of elements throughout the ocean. Remineralization of exported organic matter in the upper mesopelagic zone provides nutrients for surface production, while material exported to depths of 1000 m or more is generally considered to be sequestered — i.e. out of contact with the atmosphere for centuries or longer. The ability to accurately model a system is a reflection of the degree to which the system is understood. In the case of export, semi-empirical and simple mechanistic models show a wide range of predictive skill. This is, in part, due to the sparseness of available data, which impedes our inability to accurately represent, or even include, all relevant processes (sometimes for legitimate computational reasons). Predictions will remain uncertain without improved understanding and parameterization of key biological processes affecting export.Funding for this workshop was provided by the National Science Foundation (NSF). Coordination and logistical support for this workshop was provided by the Ocean Carbon and Biogeochemistry (OCB) Program (www.us-ocb.org

Duchamp: a 3D source finder for spectral-line data

This paper describes the Duchamp source finder, a piece of software designed to find and describe sources in 3-dimensional, spectral-line data cubes. Duchamp has been developed with HI (neutral hydrogen) observations in mind, but is widely applicable to many types of astronomical images. It features efficient source detection and handling methods, noise suppression via smoothing or multi-resolution wavelet reconstruction, and a range of graphical and text-based outputs to allow the user to understand the detections. This paper details some of the key algorithms used, and illustrates the effectiveness of the finder on different data sets.Comment: MNRAS, in press. 17 pages, 8 figure