Training Big Random Forests with Little Resources

Without access to large compute clusters, building random forests on large datasets is still a challenging problem. This is, in particular, the case if fully-grown trees are desired. We propose a simple yet effective framework that allows to efficiently construct ensembles of huge trees for hundreds of millions or even billions of training instances using a cheap desktop computer with commodity hardware. The basic idea is to consider a multi-level construction scheme, which builds top trees for small random subsets of the available data and which subsequently distributes all training instances to the top trees' leaves for further processing. While being conceptually simple, the overall efficiency crucially depends on the particular implementation of the different phases. The practical merits of our approach are demonstrated using dense datasets with hundreds of millions of training instances.Comment: 9 pages, 9 Figure

The lactation cycle of the fur seal

The fur seal is a mammal with an unusual ability to turn its milk production on and off without significantly altering the gross morphology of the mammary gland. This atypical lactation cycle is due to the fact that maternal foraging and infant nursing are spatially and temporally separate (Bonner, 1984). Maternal care involves the suckling of offspring over a period of at least 4 months, but lactation can extend to more than 12 months. Following a perinatal fast of approximately 1 week, females depart the breeding colony to forage at sea and, for the remainder of lactation, alternate between short periods ashore suckling their young with longer periods of up to 4 weeks foraging at sea. Whilst foraging at sea, milk production in the fur seal mammary gland either ceases or is reduced (Arnould &amp; Boyd, 1995b).<br /

Research partnerships across international contexts : a practice of unity or plurality?

This work was supported by Engineering and Physical Sciences Research Council [grant number EP/T025034/1].Partnership is not a benign practice; it is culturally and ethically loaded. The way in which partnerships are construed in international research determines its design, ethics and impacts. Despite this, and the growing assumption of partnership practice in our field, the concept has become increasingly abstract and the practice under-analysed. This article provides critical perspectives of current understandings of partnership in international development research from three angles: the motivations behind partnership working; an epistemological perspective in relation to epistemic justice and the agency of language; and finally, the systems that mediate partnerships, and the range of resources that guide them. Publisher PDFPeer reviewe

The Dependence of Brown Dwarf Radii on Atmospheric Metallicity and Clouds: Theory and Comparison with Observations

Employing realistic and consistent atmosphere boundary conditions, we have generated evolutionary models for brown dwarfs and very-low-mass stars (VLMs) for different metallicities ([Fe/H]), with and without clouds. We find that the spread in radius at a given mass and age can be as large as $\sim$10% to $\sim$25%, with higher-metallicity, higher-cloud-thickness atmospheres resulting quite naturally in larger radii. For each 0.1 dex increase in [Fe/H], radii increase by $\sim$1% to $\sim$2.5%, depending upon age and mass. We also find that, while for smaller masses and older ages brown dwarf radii decrease with increasing helium fraction ($Y$) (as expected), for more massive brown dwarfs and a wide range of ages they increase with helium fraction. The increase in radius in going from $Y=0.25$ to $Y=0.28$ can be as large as $\sim$0.025 \rj\ ($\sim$2.5%). Furthermore, we find that for VLMs an increase in atmospheric metallicity from 0.0 to 0.5 dex, increases radii by $\sim$4%, and from -0.5 to 0.5 dex by $\sim$10%. Therefore, we suggest that opacity due to higher metallicity might naturally account for the apparent radius anomalies in some eclipsing VLM systems. Ten to twenty-five percent variations in radius exceed errors stemming from uncertainities in the equation of state alone. This serves to emphasize that transit and eclipse measurements of brown dwarf radii constrain numerous effects collectively, importantly including the atmosphere and condensate cloud models, and not just the equation of state. At all times, one is testing a multi-parameter theory, and not a universal radius$-$mass relation.Comment: Accepted to the Astrophysical Journal, May 3, 201

Affinity Purification of Antibodies Specific for 1,4-Dihydropyridine Ca 2+ Channel Blockers

High-affinity antibodies specific for the 1,4-dihydropyridine Ca 2+ channel blockers have been produced in sheep and affinity purified using a dihydropyridine-Sepharose affinity column. Dihydropyridine-Sepharose affinity matrix was synthesized by reaction of aminohexyl-Sepharose with an affinity analogue of nifedipine, dimethyl l,4-dihydro-2,6-dimethyl-4-(2-isothiocyanatophenyl)-3,5-pyridinedicarboxylate. Residual amine groups were then blocked by carbodiimide-catalyzed acetylation. channels is important in mediation of contraction in cardiac and smooth muscle

Things can only get Stranger: theoretical and clinical reflections on Netflix’s Stranger Things

The popularity of Stranger Things lies in its ability to depict the unconscious aspects of personality and the psychological processes constellated during crucial years of development and maturation. First, Jung’s notions of the mother complex and dual mother archetype frame the metamorphoses experienced by Will Byers and El. Second, a psychoanalytic understanding of nostalgia, loss and mourning elucidates the associations audiences make between their own experiences and those of the show’s central characters. Ironically, it is through an exploration of the monstrous and the fantastic that the series draws us closer to what it means to be human; the stranger things get, the closer we come to reality and grasping the operations of the psyche

First year experience (FYE): International students’ experiences

International students confront a range of challenges during their transition to living and studying in Australia. Despite these challenges over 80% of international students reported high satisfaction with their life and study within Australia. This qualitative study reports on the experiences of 53 first year international students at ECU. Participants were students from across a range of study areas who responded to an online or face to face survey. Participants were required to respond to four questions which were analysed thematically to provide a summary of their experiences. Survey questions included their positive and negative experiences of being a first year student at ECU and changes that they suggested be considered by the university. Thematic analysis revealed a range of issues, most of which were reflected in previous research, however a range of ECU specific issues were also revealed, for example, resources and timetabling. This introductory research has provided initial data for developing future research. The cognitive nature of the survey may have limited the responses of participants. It is recommended that future research consider interviews with international students to review social and emotional issues