Implementing Student-Centered Learning Strategies for Multilingual Learners Through a Social Justice Lens

This project answers the question, How can we create an equitable student-centered environment through project and problem based learning? The research focuses on student centered learning, specifically project and problem based instruction, while creating an equitable learning environment, along with supporting learnings through differentiated instruction. The project creates a curriculum for a 7th grade Social Studies unit of study of the Foundations of Systems of Power in the United States from 1787 - 1800. Application of this curriculum is a tool that teachers can use to create a safe and equitable learning environment for all of their students

Chronic Effects of Lead Exposure on Atherinops Affinis (topsmelt): Influence of Salinity and Organism Age

Pb (lead) appears in the environment as a consequence of both natural and anthropogenic processes. Mining, smelting, coal burning, lead acid batteries, and cement manufacturing substantially release Pb into aquatic environments. The goal of this study was to determine the influence of salinity and organism age on chronic toxicity of Pb to Atherinops affinis (topsmelt) in support of development of a species sensitivity distribution (SSD). Species sensitivity distributions assist in ecological risk assessments and establishing quality criteria for contaminants. Three chronic exposure studies were conducted for 28 days in a water flow-through testing system. Survival, standard length, dry weight, and tissue Pb concentration were measured and lethal concentrations (LC), effective concentrations (EC), and bioconcentration factor (BCF) were calculated. In general, increasing salinity and organism age decreased Pb toxicity. The 28-day LC50 values for larval fish at 14 and 28 parts per thousand (ppt) salinity were 15.1 and 79.8 µg/L dissolved Pb, respectively, whereas the 28-d LC50 for juvenile fish was 167.6 µg/L dissolved Pb at 28 ppt salinity. Using standard length, the EC10 values for larval fish were 16.6 and 82.3 µg/L dissolved Pb at low and high salinity, respectively. The dry weight EC25 for low and high salinity were 15.6 and 46.9 µg/L dissolved Pb, respectively. The BCF was higher with the lower salinity study (2.00) in comparison to the higher salinity study (0.73). This is likely due to competition between salt ions and Pb at biotic ligand binding sites as well as lowered Pb speciation rates

Fracture of Laminated Bamboo and the Influence of Preservative Treatments

Treated bamboo can be made into large, durable structural elements which have the potential to become a transformative large-scale building material, but the fracture behaviour which determines their ultimate strength in various loading scenarios has not been studied. Laminated bamboo is a promising structural engineered bamboo material, and is generally made from bamboo treated to improve its durability. Studies into the structural behaviour of laminated bamboo indicate that different preservative treatments affect the structural properties of the composite differently, with conflicting evidence from tests in different load orientations. This study uses fracture mechanical testing and microscopy to develop an understanding of the fracture mechanics of engineered bamboo, and explains why the properties of the composite under tension, compression and bending may be affected differently by the treatment processes. Two types of treated Moso bamboo are studied alongside the same material with minimal processing. The treated material had gone through one of two commercial processes: bathing in a hydrogen peroxide bleach solution, or treatment by pressurised steam (described as caramelised). The results show that the critical strain energy release rate in the caramelised material is much lower than that in the bleached, and the fracture behaviour of the bleached material is closer to that of the raw bamboo. Fracture experiments included Mode I and Mode II fracture with cracks progressing parallel to the grain, and Mode I fracture with a crack progressing perpendicular to the grain. The results shed new light on the strength of structural-size elements

CARMA Survey Toward Infrared-bright Nearby Galaxies (STING): Molecular Gas Star Formation Law in NGC4254

This study explores the effects of different assumptions and systematics on the determination of the local, spatially resolved star formation law. Using four star formation rate (SFR) tracers (H\alpha with azimuthally averaged extinction correction, mid-infrared 24 micron, combined H\alpha and mid-infrared 24 micron, and combined far-ultraviolet and mid-infrared 24 micron), several fitting procedures, and different sampling strategies we probe the relation between SFR and molecular gas at various spatial resolutions and surface densities within the central 6.5 kpc in the disk of NGC4254. We find that in the high surface brightness regions of NGC4254 the form of the molecular gas star formation law is robustly determined and approximately linear and independent of the assumed fraction of diffuse emission and the SFR tracer employed. When the low surface brightness regions are included, the slope of the star formation law depends primarily on the assumed fraction of diffuse emission. In such case, results range from linear when the fraction of diffuse emission in the SFR tracer is ~30% or less (or when diffuse emission is removed in both the star formation and the molecular gas tracer), to super-linear when the diffuse fraction is ~50% and above. We find that the tightness of the correlation between gas and star formation varies with the choice of star formation tracer. The 24 micron SFR tracer by itself shows the tightest correlation with the molecular gas surface density, whereas the H\alpha corrected for extinction using an azimuthally-averaged correction shows the highest dispersion. We find that for R<0.5R_25 the local star formation efficiency is constant and similar to that observed in other large spirals, with a molecular gas depletion time ~2 Gyr.Comment: accepted for publication in ApJ, vol 729, March 10 2011 issue; 30 pages; 14 figures; revised version includes referee's comments; results unchange

Simultaneous radio and X-ray observations of Galactic Centre low mass X-ray binaries

We have performed simultaneous X-ray and radio observations of thirteen Galactic centre low-mass X-ray binaries in 1998 April using the Wide-Field Cameras onboard BeppoSAX and the Australia Telescope Compact Array, the latter simultaneously at 4.8 and 8.64 GHz. We detect two Z sources, GX 17+2 and GX 5-1, and the unusual `hybrid' source GX 13+1. Upper limits, which are significantly deeper than previous non-detections, are placed on the radio emission from two more Z sources and seven atoll sources. Hardness-Intensity diagrams constructed from the Wide-Field Camera data reveal GX 17+2 and GX 5-1 to have been on the lower part of the horizontal branch and/or the upper part of the normal branch, at the time of the observations, and the two non-detected Z sources, GX 340+0 and GX 349+2, to have been on the lower part of the normal branch. This is consistent with the previous empirically-determined relation between radio and X-ray emission from Z sources, in which radio emission is strongest on the Horizontal branch and weakest on the Flaring branch. For the first time we have information on the X-ray state of atoll sources, which are clearly radio-quiet relative to the Z sources, during periods of observed radio upper limits. We place limits on the linear polarisation from the three detected sources, and use accurate radio astrometry of GX 17+2 to confirm that it is probably not associated with the optical star NP Ser. Additionally we place strong upper limits on the radio emission from the X-ray binary 2S 0921-630, disagreeing with suggestions that it is a Z-source viewed edge-on.Comment: Accepted for publication in MNRA