A precisely controlled, low range humidity system

Development of environmental control system for determining effects of relative humidity and dry heat on inactivation of microorganism

Quantum phase transitions in the quasi-periodic kicked rotor

We present a microscopic theory of transport in quasi-periodically driven environments (`kicked rotors'), as realized in recent atom optic experiments. We find that the behavior of these systems depends sensitively on the value of Planck's constant $\tilde h$: for irrational values of $\tilde h/(4\pi)$ they fall into the universality class of disordered electronic systems and we derive the microscopic theory of the ensuing localization phenomena. In contrast, for rational values the rotor-Anderson insulator acquires an infinite (static) conductivity and turns into a `super-metal'. Signatures of the corresponding metal/super-metal transition are discussed.Comment: 4 pages, 1 figure, 1 tabl

Design requirements for laminar airflow clean rooms and devices

Laminar airflow and airborne contamination control concepts with clean room specifications and laminar flow facility design

Residential summer camp: a new venue for nutrition education and physical activity promotion

Background Millions of children attend residential summer camps each year. However, few studies have examined the potential of camps for obesity prevention efforts. Research in the domain of positive youth development has shown that camp programs as short as one week have both short- and long-term positive effects on self-esteem, self-efficacy and other youth outcomes. The objective of the present study was to highlight the potential of resident camps as promising venues for the promotion of healthy eating and physical activity behaviors in the children who attend. Methods Data for this study came from the American Camp Association 2007 Emerging Issues Survey. This survey assessed camp professionals’ perspectives on a diverse array of issues, including the healthy eating and physical activity of children. Data analysis focused on responses from 247 camp professionals whose camps offered resident camp programs. Results Descriptive and Chi-square statistics were calculated. Ninety-two percent of camp professionals reported that the healthy eating and physical activity of campers was an “important” or “very important” issue for camps. The majority of camps reported offering vegetarian options, healthy snacks and salad bars, and allergen-free options. Additionally, 86% of camp professionals indicated that they had implemented one or more strategies to address concerns related to the unhealthy eating behaviors of children, with top strategies including increasing the availability of fruits and vegetables, increasing the availability of healthy drink options, and improving the nutritional quality of menus. Fewer camp professionals (50%) indicated they had implemented strategies to increase children’s physical activity levels, but many professionals indicated that their camp programs were inherently active and additional strategies to promote physical activity were not necessary. Associations were found between camp affiliation and food options available to campers. Conclusions The majority of camp professionals believe the healthy eating and physical activity of children are important issues for camps and have implemented strategies to address these issues. An important question for future research is to examine whether these strategies are effective in promoting healthy eating and physical activity behaviors in children, as well as ways that camp programs could be improved

The development of two closely controlled humidity systems

Development of two closely controlled humidity systems for microbiolog

Neon Lights Up a Controversy: the Solar Ne/O Abundance

The standard solar model was so reliable that it could predict the existence of the massive neutrino. Helioseismology measurements were so precise that they could determine the depth of the convection zone. This agreement between theory and observation was the envy of all astrophysics -- until recently when sophisticated three-dimensional hydrodynamic calculations of the solar atmosphere reduced the metal content by a factor of almost two. Antia & Basu (2005) suggested that a higher value of the solar neon abundance, Ne/O = 0.52, would resolve this controversy. Drake & Testa (2005) presented strong evidence in favor of this idea from a sample of 21 Chandra stars with enhanced values of the neon abundance, Ne/O = 0.41. In this paper, we have analyzed solar active region spectra from the archive of the Flat Crystal Spectrometer on Solar Maximum Mission, a NASA mission from the 1980s, as well as full-Sun spectra from the pioneering days of X-ray astronomy in the 1960s. These data seem consistent with the standard neon-to-oxygen abundance value, Ne/O = 0.15 (Grevesse & Sauval 1998). If these results prove to be correct, than the enhanced-neon hypothesis will not resolve the current controversy.Comment: submitted to ApJ Letter

Benchmarking Professional Development Practices Across Youth-Serving Organizations: Implications for Extension

Examining traditional and contemporary professional development practices of youth-serving organizations can inform practices across Extension, particularly in light of the barriers that have been noted for effectively developing the professional competencies of Extension educators. With professional development systems changing quickly, particularly through online education and blended learning opportunities, benchmarks need to guide new research around best practices in professional development. Although many program providers have not established benchmarks for professional development, a few cases exist. This article examines the current state of professional development practices of youth-serving organizations and offers recommendations for improving Extension professional development practices

Emergent Lorentz symmetry with vanishing velocity in a critical two-subband quantum wire

We consider a quantum wire with two subbands of spin-polarized electrons in the presence of strong interactions. We focus on the quantum phase transition when the second subband starts to get filled as a function of gate voltage. Performing a one-loop renormalization group (RG) analysis of the effective Hamiltonian, we identify the critical fixed-point theory as a conformal field theory having an enhanced SU(2) symmetry and central charge 3/2. While the fixed point is Lorentz invariant, the effective 'speed of light' nevertheless vanishes at low energies due to marginally irrelevant operators leading to a diverging critical specific heat coefficient.Comment: 4 pages, 3 figures, minor changes, published versio

Local dynamics of topological magnetic defects in the itinerant helimagnet FeGe

Chiral magnetic interactions induce complex spin textures including helical and conical spin waves, as well as particle-like objects such as magnetic skyrmions and merons. These spin textures are the basis for innovative device paradigms and give rise to exotic topological phenomena, thus being of interest for both applied and fundamental sciences. Present key questions address the dynamics of the spin system and emergent topological defects. Here we analyze the micromagnetic dynamics in the helimagnetic phase of FeGe. By combining magnetic force microscopy, single-spin magnetometry, and Landau-Lifschitz-Gilbert simulations we show that the nanoscale dynamics are governed by the depinning and subsequent motion of magnetic edge dislocations. The motion of these topologically stable objects triggers perturbations that can propagate over mesoscopic length scales. The observation of stochastic instabilities in the micromagnetic structure provides new insight to the spatio-temporal dynamics of itinerant helimagnets and topological defects, and discloses novel challenges regarding their technological usage