Demographic fluctuations in a population of anomalously diffusing individuals

The phenomenon of spatial clustering induced by death and reproduction in a population of anomalously diffusing individuals is studied analytically. The possibility of social behaviors affecting the migration strategies has been taken into exam, in the case anomalous diffusion is produced by means of a continuous time random walk (CTRW). In the case of independently diffusing individuals, the dynamics appears to coincide with that of (dying and reproducing) Brownian walkers. In the strongly social case, the dynamics coincides with that of non-migrating individuals. In both limits, the growth rate of the fluctuations becomes independent of the Hurst exponent of the CTRW. The social behaviors that arise when transport in a population is induced by a spatial distribution of random traps, have been analyzed.Comment: 10 pages, 6 figure

Fourier's law on a one-dimensional optical random lattice

We study the transport properties of a one-dimensional hard-core bosonic lattice gas coupled to two particle reservoirs at different chemical potentials which generate a current flow through the system. In particular, the influence of random fluctuations of the underlying lattice on the stationary-state properties is investigated. We show analytically that the steady-state density presents a linear profile. The local steady-state current obeys the Fourier law $j=-\kappa(\tau)\nabla n$ where $\tau$ is a typical timescale of the lattice fluctuations and $\nabla n$ the density gradient imposed by the reservoirs.Comment: 9 pages, 2 figure

Cognitive barriers during monitoring-based commissioning of buildings

Monitoring-based commissioning (MBCx) is a continuous building energy management process used to optimize energy performance in buildings. Although monitoring-based commissioning (MBCx) can reduce energy waste by up to 20%, many buildings still underperform due to issues such as unnoticed system faults and inefficient operational procedures. While there are technical barriers that impede the MBCx process, such as data quality, the focuses of this paper are the non-technical, behavioral and organizational, barriers that contribute to issues initiating and implementing MBCx. In particular, this paper discusses cognitive biases, which can lead to suboptimal outcomes in energy efficiency decisions, resulting in missed opportunities for energy savings. This paper provides evidence of cognitive biases in decisions during the MBCx process using qualitative data from over 40 public and private sector organizations. The results describe barriers resulting from cognitive biases, listed in descending order of occurrence, including: risk aversion, social norms, choice overload, status quo bias, information overload, professional bias, and temporal discounting. Building practitioners can use these results to better understand potential cognitive biases, in turn allowing them to establish best practices and make more informed decisions. Researchers can use these results to empirically test specific decision interventions and facilitate more energy efficient decisions

On the Anomalous Temperature Distribution of the Intergalactic Medium in the NGC 3411 Group of Galaxies

We present XMM, Chandra and VLA observations of the USGC S152 group and its central elliptical NGC 3411. Imaging of the group X-ray halo suggests it is relaxed with little apparent structure. We investigate the temperature and metal abundance structure of the group halo, and find that while the abundance distribution is fairly typical, the temperature profile is highly unusual, showing a hot inner core surrounded by a cool shell of gas with a radius of \~20-40 kpc, at the center of the larger group halo. Spectral mapping confirms an irregular ring of gas ~0.15 keV cooler than its surroundings. We estimate the total mass, entropy and cooling time profiles within ~200 kpc, and find that the cool shell contains ~9x10^9 Msun of gas. VLA observations at 1.4, 5 and 8 GHz reveal a relatively weak nuclear radio source, with a core radio luminosity L_R=2.7x10^38 erg/s, and a diffuse component extended on scales of a few arcseconds (or more). A lack of evidence for activity at optical or X-ray wavelengths supports the conclusion that the central black hole is currently in a quiescent state. We discuss possible mechanisms for the formation of temperature features observed in the halo, including a previous period of AGN activity, and settling of material stripped from the halo of one of the other group member galaxies.Comment: 15 pages, 8 postscript figures, accepted for publication in ApJ version with high resolution figures available at http://hea-www.harvard.edu/~ejos/files/N3411_hires.pd

Cathodoluminescence of nanocrystalline Y2O3:Eu3+ with various Eu3+ concentrations

© The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Herein a study on the preparation and cathodoluminescence of monosized spherical nanoparticles of Y2O3:Eu3+ having a Eu3+ concentration that varies between 0.01 and 10% is described. The luminous efficiency and decay time have been determined at low a current density, whereas cathodoluminescence-microscopy has been carried out at high current density, the latter led to substantial saturation of certain spectral transitions. A novel theory is presented to evaluate the critical distance for energy transfer from Eu3+ ions in S6 to Eu3+ ions in C2 sites. It was found that Y2O3:Eu3+ with 1–2% Eu3+ has the highest luminous efficiency of 16lm/w at 15keV electron energy. Decay times of the emission from 5D0 (C2) and 5D1 (C2) and 5D0 (S6) levels were determined. The difference in decay time from the 5D0 (C2) and 5D1 (C2) levels largely explained the observed phenomena in the cathodoluminescence-micrographs recorded with our field emission scanning electron microscope

Dusty plasma cavities: probe-induced and natural

A comprehensive exploration of regional dust evacuation in complex plasma crystals is presented. Voids created in 3D crystals on the International Space Station have provided a rich foundation for experiments, but cavities in dust crystals formed in ground-based experiments have not received as much attention. Inside a modified GEC RF cell, a powered vertical probe was used to clear the central area of a dust crystal, producing a cavity with high cylindrical symmetry. Cavities generated by three mechanisms are examined. First, repulsion of micrometer-sized particles by a negatively charged probe is investigated. A model of this effect developed for a DC plasma is modified and applied to explain new experimental data in RF plasma. Second, the formation of natural cavities is surveyed; a radial ion drag proposed to occur due to a curved sheath is considered in conjunction with thermophoresis and a flattened confinement potential above the center of the electrode. Finally, cavity formation unexpectedly occurs upon increasing the probe potential above the plasma floating potential. The cavities produced by these methods appear similar, but each are shown to be facilitated by fundamentally different processes.Comment: 10 pages, 12 figure