Methods of Smile: A Science Seminar Course in Deliberate Education

Oregon State University’s Science and Math Investigative Learning Experiences (SMILE) Program is an enrichment program for minority and underrepresented K-12 students. Through an eight-year iterative process, SMILE has developed and refined a science seminar course that allows undergraduate and master’s degree students to explore science enrichment for youth. Students enrolled in the course are engaged in teaching and learning as a community of learners with a focus on service learning. The intended audience for the course is those students who are interested in working in educational settings with youth—as classroom teachers, science/mathematics professionals engaged in precollege outreach, and the like. The actual audience, though quite broad, represents those students who want to be better prepared as effective science educators in their various career roles. This article provides the context for the course, defines and examines deliberate education as illustrated by the structure and activities of the Methods of SMILE seminar course, highlights the elements of an effective community of learners as demonstrated through it, details the specific strategies and activities of it, and summarizes the next steps in identifying its impact in transforming the participants’ college experiences

Droplet size and nozzle tip pressure from a pulse-width modulation sprayer

Pulse-width modulation (PWM) sprayers can improve application accuracy through flow control, turn compensation, and high-resolution overlap control by pulsing an electronically-actuated solenoid valve which controls the relative proportion of time each solenoid valve is open (duty cycle). The objective of this experiment was to identify the droplet size distribution and nozzle tip pressure when influenced by PWM duty cycle, nozzle technology, and gauge pressure to provide PWM guidelines. The experiment was conducted in a low-speed wind tunnel at the Pesticide Application Technology Laboratory using a SharpShooter® PWM system. In general, for non-venturi nozzles, as duty cycle decreased, droplet size slightly increased between 40 and 100% duty cycles. Conversely, venturi nozzles did not always follow this trend. The lowest duty cycle evaluated (20%) negatively impacted droplet size and caused inconsistencies for all nozzle by pressure combinations. The addition of a solenoid valve lowered nozzle tip pressure while gauge pressure remained constant indicating a restriction is present within the solenoid valve. Greater orifice sizes increased the pressure loss observed. Duty cycle minimally impacted nozzle tip pressure trends which were similar to the electrical square wave PWM signals. However, venturi nozzles deviated from this trend, specifically twin-fan, single pre-orifice venturi nozzles. In conclusion, venturi nozzles are not recommended for PWM systems as they may lead to inconsistent applications, specifically in regards to droplet size generation and nozzle tip pressures. Spray pressures of 276 kPa or greater and PWM duty cycles of 40% or greater are recommended to ensure proper PWM operation

Accounting for data heterogeneity in integrative analysis and prediction methods: An application to Chronic Obstructive Pulmonary Disease

Epidemiologic and genetic studies in chronic obstructive pulmonary disease (COPD) and many complex diseases suggest subgroup disparities (e.g., by sex). We consider this problem from the standpoint of integrative analysis where we combine information from different views (e.g., genomics, proteomics, clinical data). Existing integrative analysis methods ignore the heterogeneity in subgroups, and stacking the views and accounting for subgroup heterogeneity does not model the association among the views. To address analytical challenges in the problem of our interest, we propose a statistical approach for joint association and prediction that leverages the strengths in each view to identify molecular signatures that are shared by and specific to males and females and that contribute to the variation in COPD, measured by airway wall thickness. HIP (Heterogeneity in Integration and Prediction) accounts for subgroup heterogeneity, allows for sparsity in variable selection, is applicable to multi-class and to univariate or multivariate continuous outcomes, and incorporates covariate adjustment. We develop efficient algorithms in PyTorch. Our COPD findings have identified several proteins, genes, and pathways that are common and specific to males and females, some of which have been implicated in COPD, while others could lead to new insights into sex differences in COPD mechanisms

Coherent Dynamics of Vortex Formation in Trapped Bose-Einstein Condensates

Simulations of a rotationally stirred condensate show that a regime of simple behaviour occurs in which a single vortex cycles in and out of the condensate. We present a simple quantitative model of this behaviour, which accurately describes the full vortex dynamics, including a critical angular speed of stirring for vortex formation. A method for experimentally preparing a condensate in a central vortex state is suggested.Comment: 4 pages, 4 figures, REVTeX 3.1; Submitted to Physical Review Letters (5 February 1999); See http://www.physics.otago.ac.nz/research/bec/vortex for MPEG movies and further information; Accepted for Physical Review Letters (24 June 1999); Changes: updated Figs 1 and 2 (new style), minor typos fixed, more discussion at en

Effect of quantum group invariance on trapped Fermi gases

We study the properties of a thermodynamic system having the symmetry of a quantum group and interacting with a harmonic potential. We calculate the dependence of the chemical potential, heat capacity and spatial distribution of the gas on the quantum group parameter $q$ and the number of spatial dimensions $D$. In addition, we consider a fourth-order interaction in the quantum group fields $\Psi$, and calculate the ground state energy up to first order.Comment: LaTeX file, 20 pages, four figures, uses epsf.sty, packaged as a single tar.gz uuencoded fil

Rotating Bose gas with hard-core repulsion in a quasi-2D harmonic trap: vortices in BEC

We consider a gas of N(=6, 10, 15) Bose particles with hard-core repulsion, contained in a quasi-2D harmonic trap and subjected to an overall angular velocity $\Omega$ about the z-axis. Exact diagonalization of the $n\times n$ many-body Hamiltonian matrix in given subspaces of the total (quantized) angular momentum L$_{z}$, with $n\sim 10^{5}$(e.g. for L$_{z}$=N=15, n =240782) was carried out using Davidson's algorithm. The many-body variational ground state wavefunction, as also the corresponding energy and the reduced one-particle density-matrix were calculated. With the usual identification of $\Omega$ as the Lagrange multiplier associated with L$_{z}$ for a rotating system, the $L_{z}-\Omega$ phase diagram (or the stability line) was determined that gave a number of critical angular velocities $\Omega_{{\bf c}i}, i=1,2,3,... ,$ at which the ground state angular momentum and the associated condensate fraction undergo abrupt jumps. A number of (total) angular momentum states were found to be stable at successively higher critical angular velocities $\Omega_{{\bf c}i}, \ i=1,2,3,...$for a given N. For$L_{z}>N$, the condensate was strongly depleted. The critical$\Omega_{{\bf c}i}$values, however, decreased with increasing interaction strength as well as the particle number, and were systematically greater than the non-variational Yrast-state values for the single vortex state with L$_{z}$=N. We have also observed that the condensate fraction for the single vortex state (as also for the higher vortex states) did not change significantly even as the 2-body interaction strength was varied over several$(\sim 4)$ orders of magnitude in the moderately to the weakly interacting regime.Comment: Revtex, 11 pages, 1 table as ps file, 4 figures as ps file

Fermi-Bose quantum degenerate ^40 K - ^87 Rb mixture with attractive interaction

We report on the achievement of simultaneous quantum degeneracy in a mixed gas of fermionic ^40 K and bosonic ^87 Rb. Potassium is cooled to 0.3 times the Fermi temperature by means of an efficient thermalization with evaporatively cooled rubidium. Direct measurement of the collisional cross-section confirms a large interspecies attraction. This interaction is shown to affect the expansion of the Bose-Einstein condensate released form the magnetic trap, where it is immersed in the Fermi sea.Comment: 5 pages, 4 figures, replaced one figure plus some change

Splitting of a doubly quantized vortex through intertwining in Bose-Einstein condensates

The stability of doubly quantized vortices in dilute Bose-Einstein condensates of 23Na is examined at zero temperature. The eigenmode spectrum of the Bogoliubov equations for a harmonically trapped cigar-shaped condensate is computed and it is found that the doubly quantized vortex is spectrally unstable towards dissection into two singly quantized vortices. By numerically solving the full three-dimensional time-dependent Gross-Pitaevskii equation, it is found that the two singly quantized vortices intertwine before decaying. This work provides an interpretation of recent experiments [A. E. Leanhardt et al. Phys. Rev. Lett. 89, 190403 (2002)].Comment: 4 pages, 3 figures (to be published in PRA

Phase diagram of quantized vortices in a trapped Bose-Einstein condensed gas

We investigate the thermodynamic stability of quantized vortices in a dilute Bose gas confined by a rotating harmonic trap at finite temperature. Interatomic forces play a crucial role in characterizing the resulting phase diagram, especially in the large $N$ Thomas-Fermi regime. We show that the critical temperature for the creation of stable vortices exhibits a maximum as a function of the frequency of the rotating trap and that the corresponding transition is associated with a discontinuity in the number of atoms in the condensate. Possible strategies for approaching the vortical region are discussed.Comment: Revtex, 4 pages, 2 figure

Activity driven modeling of time varying networks

Network modeling plays a critical role in identifying statistical regularities and structural principles common to many systems. The large majority of recent modeling approaches are connectivity driven. The structural patterns of the network are at the basis of the mechanisms ruling the network formation. Connectivity driven models necessarily provide a time-aggregated representation that may fail to describe the instantaneous and fluctuating dynamics of many networks. We address this challenge by defining the activity potential, a time invariant function characterizing the agents' interactions and constructing an activity driven model capable of encoding the instantaneous time description of the network dynamics. The model provides an explanation of structural features such as the presence of hubs, which simply originate from the heterogeneous activity of agents. Within this framework, highly dynamical networks can be described analytically, allowing a quantitative discussion of the biases induced by the time-aggregated representations in the analysis of dynamical processes.Comment: 10 pages, 4 figure