Visualizing superdiversity and “seeing” urban socio-economic complexity.

Recent migration has made traditional destination cities so diversethat many conventional social science concepts and methods havebecome inadequate to the task of understanding complex diversity,or what is now often termed superdiversity. Here, we address theneed for new methods of "seeing" urban superdiversity in twoways. First, we highlight the need to understand urban contextsby examining new combinations and intersections of multiplesocial variables. Second, we demonstrate a suite of newinteractive tools. We attempt to enable users to picture, perceiveand apprehend complex analyses of multidimensional data onurban diversity in new, more intuitive ways. This visualizationdraws on multivariate geo-spatial data on different kinds ofdiversity, across three major destination cities: Sydney, Vancouver,and Auckland. We believe this approach contributes to thetheoretical and methodological refinements needed to studycontemporary superdiversity in urban settings, and to contributeto better public understanding and policies regarding theprocesses of urban diversificatio

Time-resolved ferromagnetic resonance in epitaxial Fe1-xCox films

Magnetodynamics in epitaxial Fe1-xCox films on GaAs (100) are studied using time-resolved ferromagnetic resonance, in which the free precession of the magnetization after an impulsive excitation is measured using the polar Kerr effect. The sample is rotated with respect to the static and pulsed field directions, providing a complete mapping of the free energy surface and characteristic relaxation times. The magnetic response can be simulated with a simple coherent rotation model except in the immediate vicinity of switching fields. Bulk and surface anisotropies are identified, and unusual dynamics associated with the coexistence of cubic and uniaxial anisotropies are observed.Comment: PDF - 4 figure

Network mechanisms of intentional learning.

The ability to learn new tasks rapidly is a prominent characteristic of human behaviour. This ability relies on flexible cognitive systems that adapt in order to encode temporary programs for processing non-automated tasks. Previous functional imaging studies have revealed distinct roles for the lateral frontal cortices (LFCs) and the ventral striatum in intentional learning processes. However, the human LFCs are complex; they house multiple distinct sub-regions, each of which co-activates with a different functional network. It remains unclear how these LFC networks differ in their functions and how they coordinate with each other, and the ventral striatum, to support intentional learning. Here, we apply a suite of fMRI connectivity methods to determine how LFC networks activate and interact at different stages of two novel tasks, in which arbitrary stimulus-response rules are learnt either from explicit instruction or by trial-and-error. We report that the networks activate en masse and in synchrony when novel rules are being learnt from instruction. However, these networks are not homogeneous in their functions; instead, the directed connectivities between them vary asymmetrically across the learning timecourse and they disengage from the task sequentially along a rostro-caudal axis. Furthermore, when negative feedback indicates the need to switch to alternative stimulus-response rules, there is additional input to the LFC networks from the ventral striatum. These results support the hypotheses that LFC networks interact as a hierarchical system during intentional learning and that signals from the ventral striatum have a driving influence on this system when the internal program for processing the task is updated.This work was supported by Medical Research Council Grant (U1055.01.002.00001.01) and a European Research GrantPCIG13-GA-2013-618351 to AH. JBR is supported by the Wellcome Trust (103838). The authors report no conflicts of interest.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroimage.2015.11.06

Operational Comparison of Three Electrofishing Systems

Three different electrofishing systems were compared to determine their relative efficiency with respect to species and numbers of fish collected. These results indicated that modifications or changes in electrofishing gear during a monitoring program should not be made unless it can be demonstrated that collecting efficiency is not altered

Observation of Magnetic Supercooling of the Transition to the Vortex State

We demonstrate that the transition from the high-field state to the vortex state in a nanomagnetic disk shows the magnetic equivalent of supercooling. This is evidence that this magnetic transition can be described in terms of a modified Landau first-order phase transition. To accomplish this we have measured the bulk magnetization of single magnetic disks using nanomechanical torsional resonator torque magnetometry. This allows observation of single vortex creation events without averaging over an array of disks or over multiple runs.Comment: 11 pages preprint, 4 figures, accepted to New Journal of Physic

The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array

The influence of nonmagnetic central node defect on dynamical properties of regular square-shaped 5 x 5 segment of magnetic dot array under the thermal activation is investigated via computer simulations. Using stochastic Landau-Lifshitz-Gilbert equation we simulate hysteresis and relaxation processes. The remarkable quantitative and qualitative differences between magnetic dot arrays with nonmagnetic central node defect and magnetic dot arrays without defects have been found.Comment: 4 pages,5 figures, submitted to J. Magn. Magn. Matte

Imaging of Spin Dynamics in Closure Domain and Vortex Structures

Time-resolved Kerr microscopy is used to study the excitations of individual micron- scale ferromagnetic thin film elements in their remnant state. Thin (18 nm) square elements with edge dimensions between 1 and 10 $\mu$m form closure domain structures with 90 degree Neel walls between domains. We identify two classes of excitations in these systems. The first corresponds to precession of the magnetization about the local demagnetizing field in each quadrant, while the second excitation is localized in the domain walls. Two modes are also identified in ferromagnetic disks with thicknesses of 60 nm and diameters from 2 $\mu$m down to 500 nm. The equilibrium state of each disk is a vortex with a singularity at the center. As in the squares, the higher frequency mode is due to precession about the internal field, but in this case the lower frequency mode corresponds to gyrotropic motion of the entire vortex. These results demonstrate clearly the existence of well-defined excitations in inhomogeneously magnetized microstructures.Comment: PDF File (Figures at reduced resolution

Fitness Correlates Of Song Repertoire Size In Free-Living Song Sparrows (Melospiza Melodia)

Models of sexual selection propose that exaggerated secondary sexual ornaments indicate a male\u27s own fitness and the fitness of his offspring. These hypotheses have rarely been thoroughly tested in free-living individuals because overall fitness, as opposed to fitness components, is difficult to measure. We used 20 years of data from song sparrows ( Melospiza melodia) inhabiting Mandarte Island, British Columbia, Canada, to test whether a male\u27s song repertoire size, a secondary sexual trait, predicted overall measures of male or offspring fitness. Males with larger song repertoires contributed more independent and recruited offspring, and independent and recruited grandoffspring, to Mandarte\u27s population. This was because these males lived longer and reared a greater proportion of hatched chicks to independence from parental care, not because females mated to males with larger repertoires laid or hatched more eggs. Furthermore, independent offspring of males with larger repertoires were more likely to recruit and then to leave more grandoffspring than were offspring of males with small repertoires. Although we cannot distinguish whether observed fitness variation reflected genetic or environmental effects on males or their offspring, these data suggest that female song sparrows would gain immediate and intergenerational fitness benefits by pairing with males with large song repertoires

Imaging the dephasing of spin wave modes in a square thin film magnetic element

Copyright © 2004 The American Physical SocietyWe have used time-resolved scanning Kerr effect microscopy to study dephasing of spin wave modes in a square Ni81Fe19 element of 10 μm width and 150 nm thickness. When a static magnetic field H was applied parallel to an edge of the square, demagnetized regions appeared at the edges orthogonal to the field. When H was applied along a diagonal, a demagnetized region appeared along the opposite diagonal. Time-resolved images of the out-of-plane magnetization component showed stripes that lie perpendicular to H and indicate the presence of spin wave modes with wave vector parallel to the static magnetization. The transient Kerr rotation was measured at different positions along an axis parallel to H, and the power spectra revealed a number of different modes. Micromagnetic simulations reproduce both the observed images and the mode frequencies. This study allows us to understand an anisotropic damping observed at the center of the square element in terms of dephasing of the resonant mode spectrum