Understanding animal social structure: exponential random graph models in animal behaviour research

M.J.S. is funded by a NERC grant NE/M004546/1. D.N.F. is funded by the Natural Sciences and Engineering Research Council of Canada. We thank Jared Wilson-Aggarwal for helpful discussions and two anonymous referees for constructive comments that improved the article.Peer reviewedPublisher PD

Dynamic networks of fighting and mating in a wild cricket population

Acknowledgements We thank Paul Hopwood, Alex Thornton, Andrew Jackson and two anonymous referees for comments that improved this manuscript. We also thank Luke Meadows and Carlos Rodríguez del Valle for assistance with data collection. This work was supported by the Natural Environment Research Council (NERC, U.K.); studentship:NE/H02249X/1; standard grants: NE/E005403/1, NE/H02364X/1,NE/L003635/1, NE/R000328/1.Peer reviewedPublisher PD

Electron - nuclear recoil discrimination by pulse shape analysis

In the framework of the ``ULTIMA'' project, we use ultra cold superfluid 3He bolometers for the direct detection of single particle events, aimed for a future use as a dark matter detector. One parameter of the pulse shape observed after such an event is the thermalization time constant. Until now it was believed that this parameter only depends on geometrical factors and superfluid 3He properties, and that it is independent of the nature of the incident particles. In this report we show new results which demonstrate that a difference for muon- and neutron events, as well as events simulated by heater pulses exist. The possibility to use this difference for event discrimination in a future dark matter detector will be discussed.Comment: Proseedings of QFS 2007, Kazan, Russia; 8 pages, 4 figures. Submited to J. Low Temp. Phy

Observation of Crossover from Ballistic to Diffusion Regime for Excimer Molecules in Superfluid 4^4He

We have measured the temperature dependence of the time of flight of helium excimer molecules He2* in superfluid 4He and find that the molecules behave ballistically below 100mK and exhibit Brownian motion above 200 mK. In the intermediate temperature range the transport cannot be described by either of the models.Comment: 8 pages, 6 figures, submitted to the Proceedings of the International Conference on Quantum Fluids and Solids 201

Topological Defects in an Open Universe

(To appear in Nuclear Physics B Supplements Proceedings section) This talk will explore the evolution of topological defects in an open universe. The rapid expansion of the universe in an open model slows defects and suppresses the generation of CBR fluctuations at large angular scale as does the altered relationship between angle and length in an open universe. Defect models, when normalized to COBE in an open universe, predict a galaxy power spectrum consistent with the galaxy power spectrum inferred from the galaxy surveys and do not require an extreme bias. Neither defect models in a flat universe nor standard inflationary models can fit either the multipole spectrum or the power spectrum inferred from galaxy surveys.Comment: 11 pages and 4 figures, Elsevier Publisher's LaTeX, POP-54

BPA uptake in rat tissues after partial hepatectomy

In boron neutron capture therapy (BNCT), boron given as boronophenylalanine (BPA) accumulates transiently not only in tumors but also in normal tissues. Average boron concentrations in transplanted 9L gliosarcoma tumors of 20 rats were 2.5 to 3.7 times concentrations found in blood. Although boron levels in a variety of tissues were also higher than blood the concentrations were less than the lowest found in the tumor. Further note than although BPA is a structural analogue of phenylalanine (Phe), the pathway of BPA uptake into regenerating liver may not be linked to Phe uptake mechanisms

Effective Actions and Phase Fluctuations in d-wave Superconductors

We study effective actions for order parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the $c$-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum XY model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero temperature superfluid stiffness, but thermal effects are small for $T << T_c$.Comment: Some numerical estimates corrected and figures changed. to appear in PRB, Sept.1 (2000

Traveling wave fronts and the transition to saturation

We propose a general method to study the solutions to nonlinear QCD evolution equations, based on a deep analogy with the physics of traveling waves. In particular, we show that the transition to the saturation regime of high energy QCD is identical to the formation of the front of a traveling wave. Within this physical picture, we provide the expressions for the saturation scale and the gluon density profile as a function of the total rapidity and the transverse momentum. The application to the Balitsky-Kovchegov equation for both fixed and running coupling constants confirms the effectiveness of this method.Comment: 9 pages, 3 figures, references adde

Processes in model slopes made of mixtures of wettable and water repellent sand: Implications for the initiation of debris flows in dry slopes

Debris flows in slopes initially dry, such as post-wildfire debris flows, are initiated by surface runoff and sediment bulking due to reduced infiltration. Soil water repellency, extreme dry soils, and loose, cohesionless materials influence their initiation. The exact link between these features, the resulting infiltration processes and the initiation mechanism of a debris flow remains unclear. Here, we examine the relation between soil particle wettability and slope processes in physical models. Flume experiments were conducted in 10% increments of mass ratios of wettable to water repellent sand, subjected to artificial rainfall with monitoring of soil water content, pore water pressure, sediment and water discharge and failure mode. To date, wettability was considered only for the water repellent end, because it reduces infiltration, enhancing surface runoff. This study demonstrates that slight wettability changes, in the full wettable to water repellent range, impact a variety of slope processes. The two extremes, fully wettable and water repellent gave opposite responses, retrogressive slides for infiltration-initiated in wettable sand and erosion by surface runoff in water repellent sand. The transition was dominated by surface runoff and preferential flow, yielding a combination of erosion and slides. From the tests, a continuous capping effect generated by water repellency was a necessary condition for erosion and sand bulking i.e., the generation of runoff-initiated debris flows. The sensitivity of the model slope response to artificial rainfall was particularly acute at high ratios of wettable to water repellent sand. For mixtures above a critical ratio of wettable to water repellent sand, the measurements with an index test revealed a fully wettable material despite differences in the infiltration, saturation and pore water pressure built-up trends. Implications for post-wildfire debris flows and debris flows in slopes initially dry in general are discussed.postprin

The Five Factor Model of personality and evaluation of drug consumption risk

The problem of evaluating an individual's risk of drug consumption and misuse is highly important. An online survey methodology was employed to collect data including Big Five personality traits (NEO-FFI-R), impulsivity (BIS-11), sensation seeking (ImpSS), and demographic information. The data set contained information on the consumption of 18 central nervous system psychoactive drugs. Correlation analysis demonstrated the existence of groups of drugs with strongly correlated consumption patterns. Three correlation pleiades were identified, named by the central drug in the pleiade: ecstasy, heroin, and benzodiazepines pleiades. An exhaustive search was performed to select the most effective subset of input features and data mining methods to classify users and non-users for each drug and pleiad. A number of classification methods were employed (decision tree, random forest, $k$-nearest neighbors, linear discriminant analysis, Gaussian mixture, probability density function estimation, logistic regression and na{\"i}ve Bayes) and the most effective classifier was selected for each drug. The quality of classification was surprisingly high with sensitivity and specificity (evaluated by leave-one-out cross-validation) being greater than 70\% for almost all classification tasks. The best results with sensitivity and specificity being greater than 75\% were achieved for cannabis, crack, ecstasy, legal highs, LSD, and volatile substance abuse (VSA).Comment: Significantly extended report with 67 pages, 27 tables, 21 figure