Wendy Keeney-Kennicutt

Effectiveness of virtual reality-based instruction on students' learning outcomes in K-12 and higher education: A meta-analysis

The purpose of this meta-analysis is to examine overall effect as well as the impact of selected instructional design principles in the context of virtual reality technology-based instruction (i.e. games, simulation, virtual worlds) in K-12 or higher education settings. A total of 13 studies (N?=?3081) in the category of games, 29 studies (N?=?2553) in the category of games, and 27 studies (N?=?2798) in the category of virtual worlds were meta-analyzed. The key inclusion criteria were that the study came from K-12 or higher education settings, used experimental or quasi-experimental research designs, and used a learning outcome measure to evaluate the effects of the virtual reality-based instruction.Results suggest games (FEM?=?0.77; REM?=?0.51), simulations (FEM?=?0.38; REM?=?0.41), and virtual worlds (FEM?=?0.36; REM?=?0.41) were effective in improving learning outcome gains. The homogeneity analysis of the effect sizes was statistically significant, indicating that the studies were different from each other. Therefore, we conducted moderator analysis using 13 variables used to code the studies. Key findings included that: games show higher learning gains than simulations and virtual worlds. For simulation studies, elaborate explanation type feedback is more suitable for declarative tasks whereas knowledge of correct response is more appropriate for procedural tasks. Students performance is enhanced when they conduct the game play individually than in a group. In addition, we found an inverse relationship between number of treatment sessions learning gains for games.With regards to the virtual world, we found that if students were repeatedly measured it deteriorates their learning outcome gains. We discuss results to highlight the importance of considering instructional design principles when designing virtual reality-based instruction. A comprehensive review of virtual reality-based instruction research.Analysis of the moderation effects of design features in a virtual environment.Using an advance statistical technique of meta-analysis to study the effects.Virtual reality environment is effective for teaching in K-12 and higher education.Results can be used by instructional designers to design the virtual environments.

The redox chemistry of Pu(V)O2+ interaction with common mineral surfaces in dilute solutions and seawater

Abstract It has long been recognized that the Pu 4+ ion can be readily adsorbed on solid surfaces, but it has been assumed that the generally more abundant Pu(V)O 2 + ion should have little affinity for surfaces. Our results indicate that Pu(V)O 2 + can be adsorbed from dilute solutions and seawater on goethite, aragonite, calcite, and δ-MnO 2 . Adsorption on δ-MnO 2 is severely depressed in seawater, probably as a result of site competition with seawater cations. The sorption behavior of PuO 2 + is influenced by oxidation-reduction reactions occurring on the mineral surfaces. Adsorption on δ-MnO 2 results in oxidation of adsorbed Pu(IV) and Pu(V) to Pu(VI). However, adsorption on goethite results in a reaction in which Pu(IV) and Pu(VI) are formed on the mineral surface. The Pu(VI) is slowly reduced to Pu(IV), leaving Pu(IV) as the dominant surface Pu species. This reaction can be photochemically catalyzed. PuO 2 + adsorbed on carbonate minerals behaves similarly to Np(V)O 2 + and undergoes little change in oxidation state after adsorption.

Distribution and Chemistry of Manganese, Iron, and Suspended Particulates in Orca Basin

The intense halocline and redoxcline in the Orca Basin, northwest Gulf of Mexico, induce dramatic water column profiles for manganese, iron, and suspended particulates. Within a 17 m interval, the salinity of the basin water increases from 66 to ≈260 & permil and dissolved oxygen decreases to zero. Midway through this transition zone, concentrations of suspended matter peak at ≈900 μg/liter. Dissolved iron and manganese concentrations in the anoxic brine increase from oceanic values to maxima of 1.6 and 22 mg/liter, respectively. Upward migration of dissolved manganese from the brine leads to production of manganese-rich particles in the slightly oxygenated overlying water.

The interaction of Np(V)O2+ with common mineral surfaces in dilute aqueous solutions and seawater

The extent and kinetics of Np(V)O2+ adsorption from dilute aqueous solutions and seawater onto a variety of synthetic and natural solids were determined at 25°C and 1 atm total pressure. Extensive and complex adsorption reactions were found, contrary to speculations in the literature that NpO2+ should behave as a simple monovalent ion with a low affinity for surfaces. When normalized to adsorption per unit solid surface area, the ranking for the synthetic solids was aragonite ⩾ calcite > goethite ⪢ MnO2 ≈ clays. Natural materials generally followed the same behavior patterns as their synthetic counterparts. The dissolved/adsorbed ratio was found to be constant over a wide range (10−13–10−7M) of NpO2+ concentrations. At higher concentrations the extent of adsorption decreased until a solubility limit was reached at approximately 10−5 M. Solution composition had the most significant influence for NpO2+ adsorption on goethite, where much more extensive adsorption occurs in dilute solutions than in seawater. When seawater is added to a dilute solution, extensive desorption of NpO2+ from goethite occurs. Tests conducted on NpO2+ adsorbed on carbonates indicated that it remained in the V oxidation state. There is a growing consensus that Pu dissolved in natural waters also occurs dominantly in the V oxidation state as PuO2+ ion. Consequently, these results for NpO2+ may serve as a guide for Pu behavior when also in the V oxidation state. The fact that most adsorbed Pu is found in the III or IV oxidation states indicates that reduction of Pu may occur subsequent to adsorption in the V oxidation state.

The stable isotopic composition of photosynthetic pigments and related biochemicals

The stable carbon and nitrogen isotopic composition of bulk organic matter, lipids, chlorophylla, chlorophyllb and β,β-carotene were determined for selected photosynthetic plants. Lipids are depleted in13C (∼ − 6‰) compared to bulk organic matter. C4- and C3-type biosynthesis can be differentiated at the compound class and individual compound level by their stable carbon isotope ratios. The stable carbon isotopic ratios of chlorophylls isolated from C3 and C4 plants differ by ∼ 10ℵ.. The stable nitrogen isotope ratios of lipids vary over an ∼ 15‰ range, excluding one very positive sample. Various sources of carbon and nitrogen, differing assimilation mechanisms, and nutrient limitation contribute to the observed isotopic compositions. The stable isotopic composition of chlorophyllf and bulk organic matter are linearly correlated. Based on this relationship it is possible to resolve the assimilation of carbon and nitrogen by algae within complex mixture of detritus, bacteria and phytoplankton. The isotopic record of photosynthetic fixation of carbon and nitogren in chlorophylls suggests that geoporphyrins do retain information on paleo-productivity. The stable isotopic composition of chlorophylla, chlorophyllb and β,β-carotene, and their breakdown products provide unique insight into a wide range of biogeochemical processes.

The geochemistry of trace metals in the Brazos River estuary

Abstract A seasonal study of trace metal behavior and transport in the Brazos River estuary was conducted in the winter, spring and fall of 1981. Surface water was analyzed for total dissolved Pb, Cu, Mn and Fe, and particulate Cd, Pb, Cu, Mn and Fe. Ancillary data included river discharge, total suspended matter, pH, major ions, nutrients, dissolved and particulate organic carbon and humic acid. The major ions were generally conservative across the river water-seawater mixing zone; however, a significant input of alkalinity and Ca was measured in the spring, attributable to cation exchange on clays and sediment diagenetic processes. Distinct concentration maxima were found in the 3–10‰ chlorinity range for dissolved Pb (0·06–0·9 n m ), Cu (6–42 n m ), Mn (2–290 n m ) and Fe (5–80 n m ). Particulate metal concentrations showed significant seasonal and spatial variations: Cd, 0·09–0·57 ppm; Pb, 15–43 ppm; Cu, 12–32 ppm; Mn, 250–1990 ppm and Fe 0·5–5·4%. Reducing conditions leading to diagenetic remobilization in estuarine sediments are proposed to be an important source of dissolved metals for estuarine water. Calculations of dissolved riverine metal transport to the ocean that include estuarine metal input are as much as 40 times greater than when estuarine processes are ignored.

Exploring 3-D Virtual Reality Technology for Spatial Ability and Chemistry Achievement.

We investigated the potential of Second Life® (SL), a three-dimensional (3-D) virtual world, to enhance undergraduate students’ learning of a vital chemistry concept. A quasi-experimental pre-posttest control group design was used to conduct the study. A total of 387 participants completed three assignment activities either in SL or using two-dimensional (2-D) images. Students were administered an 11-question chemistry achievement test and two measures of spatial ability (Purdue Visualization of Rotations Test, Card Rotations Test). Although analyses of covariance revealed no statistically significant differences between the two groups as a whole for any of the outcome measures, a subgroup analyses was conducted to decompose the relative impact of 3-D virtual reality instruction within SL. We found that students classified as having poor spatial ability showed significantly greater improvement in understanding the 3-D nature of molecules if they did relevant activities in a 3-D virtual world than those students who only worked with 2-D images.