591 research outputs found

    Hike Your Own Hike: Cosmopolitanism and Applied Behavior Analysis Explored Through SPN

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    Ever since I started working with animals, I felt an intrinsic motivation to develop relationships based on trust and mutual admiration. Working in the horse world, I became dismayed at the coercive methods used to assure progress and achieve competition goals. I moved to Burlington to pursue a career helping children. Working as a behavior interventionist I felt peace and satisfaction as I utilized my previous skills and knowledge learned from my work with animals and my undergraduate education. After about a year of work, I started to become frustrated and dismayed at the treatment of some of our children. This SPN thesis is an exploration of those challenges and who I wish to become as I move forward in my career

    Information-theoretic measures of superconductivity in a two-dimensional doped Mott insulator

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    A key open issue in condensed matter physics is how quantum and classical correlations emerge in an unconventional superconductor from the underlying normal state. We study this problem in a doped Mott insulator with information theory tools on the two-dimensional Hubbard model at finite temperature with cluster dynamical mean-field theory. We find that the local entropy detects the superconducting state and that the difference in the local entropy between the superconducting and normal states follows the same difference in the potential energy. We find that the thermodynamic entropy is suppressed in the superconducting state and monotonically decreases with decreasing doping. The maximum in entropy found in the normal state above the overdoped region of the superconducting dome is obliterated by superconductivity. The total mutual information, which quantifies quantum and classical correlations, is amplified in the superconducting state of the doped Mott insulator for all doping levels, and shows a broad peak versus doping, as a result of competing quantum and classical effects.Comment: 8 pages, 4 figures, and supplementary information; accepted versio

    Specific heat maximum as a signature of Mott physics in the two-dimensional Hubbard model

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    Recent experiments on cuprates show that as a function of doping, the normal-state specific heat sharply peaks at the doping δ∗\delta^*, where the pseudogap ends at low temperature. This finding is taken as the thermodynamic signature of a quantum critical point, whose nature has not yet been identified. Here we present calculations for the two-dimensional Hubbard model in the doped Mott insulator regime, which indicate that the specific heat anomaly can arise from the finite temperature critical endpoint of a first-order transition between a pseudogap phase with dominant singlet correlations and a metal. As a function of doping at the temperature of the endpoint, the specific heat diverges. Upon increasing temperature, the peak becomes broader. The diverging correlation length is associated with uniform density fluctuations. No broken symmetries are needed. These anomalies also occur at half-filling as a function of interaction strength, and are relevant for organic superconductors and ultracold atoms.Comment: 6 pages, 3 figures; published versio

    Critical opalescence across the doping driven Mott transition in optical lattices of ultracold atoms

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    Phase transitions and their associated crossovers are imprinted in the behavior of fluctuations. Motivated by recent experiments on ultracold atoms in optical lattices, we compute the thermodynamic density fluctuations δN2\delta N^2 of the two-dimensional fermionic Hubbard model with plaquette cellular dynamical mean-field theory. To understand the length scale of these fluctuations, we separate the local from the nonlocal contributions to δN2\delta N^2. We determine the effects of particle statistics, interaction strength UU, temperature TT and density nn. At high temperature, our theoretical framework reproduces the experimental observations in the doping-driven crossover regime between metal and Mott insulator. At low temperature, there is an increase of thermodynamic density fluctuations, analog to critical opalescence, accompanied by a surprising reduction of the absolute value of their nonlocal contributions. This is a precursory sign of an underlying phase transition between a pseudogap phase and a metallic phase in doped Mott insulators, which should play an important role in the cuprate high-temperature superconductors. Predictions for ultracold atom experiments are made.Comment: 10 pages, 4 figures; published versio

    An Experimental Field Study of Delayed Density Dependence in Natural Populations of Aedes albopictus

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    Aedes albopictus, a species known to transmit dengue and chikungunya viruses, is primarily a container-inhabiting mosquito. The potential for pathogen transmission by Ae. albopictus has increased our need to understand its ecology and population dynamics. Two parameters that we know little about are the impact of direct density-dependence and delayed density-dependence in the larval stage. The present study uses a manipulative experimental design, under field conditions, to understand the impact of delayed density dependence in a natural population of Ae. albopictus in Raleigh, North Carolina. Twenty liter buckets, divided in half prior to experimentation, placed in the field accumulated rainwater and detritus, providing oviposition and larval production sites for natural populations of Ae. albopictus. Two treatments, a larvae present and larvae absent treatment, were produced in each bucket. After five weeks all larvae were removed from both treatments and the buckets were covered with fine mesh cloth. Equal numbers of first instars were added to both treatments in every bucket. Pupae were collected daily and adults were frozen as they emerged. We found a significant impact of delayed density-dependence on larval survival, development time and adult body size in containers with high larval densities. Our results indicate that delayed density-dependence will have negative impacts on the mosquito population when larval densities are high enough to deplete accessible nutrients faster than the rate of natural food accumulation

    The Grizzly, February 18, 2010

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    Every Ending Starts with a Beginning • Record-Breaking Blizzard Evokes Varied Reactions • Could Watching the Super Bowl Damage Your Heart? • Snow Storm Photos • Senior Class Gift Drive • SPINTfest \u2710 Brings New Themes for Houses • UC Goes Red to Raise Awareness About the Risks of Heart Disease • Opinion: Teenage Pregnancy TV Shows are a Big Hit, But What\u27s the Effect? • Tragedy Strikes in Early Hours of Winter Olympics • Men\u27s Basketball Shuts Down McDanielhttps://digitalcommons.ursinus.edu/grizzlynews/1806/thumbnail.jp

    Local Entanglement Entropy and Mutual Information across the Mott Transition in the Two-Dimensional Hubbard Model

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    Entanglement and information are powerful lenses to probe phases transitions in many-body systems. Motivated by recent cold atom experiments, which are now able to measure the corresponding information-theoretic quantities, we study the Mott transition in the half-filled two-dimensional Hubbard model using cellular dynamical mean-field theory, and focus on two key measures of quantum correlations: entanglement entropy and mutual information. We show that they detect the first-order nature of the transition, the universality class of the endpoint, and the crossover emanating from the endpoint.Comment: 6 pages, 3 figure
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