Leveling transparency via situated intermediary learning objectives (SILOs)

When designers set out to create a mathematics learning activity, they have a fair sense of its objectives: students will understand a concept and master relevant procedural skills. In reform-oriented activities, students first engage in concrete situations, wherein they achieve situated, intermediary learning objectives (SILOs), and only then they rearticulate their solutions formally. We define SILOs as heuristics learners devise to accommodate contingencies in an evolving problem space, e.g., monitoring and repairing manipulable structures so that they model with fidelity a source situation. Students achieve SILOs through problem-solving with media, instructors orient toward SILOs via discursive solicitation, and designers articulate SILOs via analyzing implementation data. We describe the emergence of three SILOs in developing the activity Giant Steps for Algebra. Whereas the notion of SILOs emerged spontaneously as a framework to organize a system of practice, i.e. our collaborative design, it aligns with phenomenological theory of knowledge as instrumented action

Apollo experience report: The AN/ARD-17 direction finding system

This report contains a statement of the operational philosophy and requirements leading to the development of the AN/ARD-17 direction-finding system. The technical problems encountered and the solutions devised in the AN/ARD-17 development are discussed. An evaluation of the system under actual operational conditions is included

IRS Scan-mapping of the Wasp-waist Nebula (IRAS 16253–2429). I. Derivation of Shock Conditions from H_2 Emission and Discovery of 11.3 μm PAH Absorption

The outflow driven by the Class 0 protostar, IRAS 16253–2429, is associated with bipolar cavities visible in scattered mid-infrared light, which we refer to as the Wasp-Waist Nebula. InfraRed Spectometer (IRS) scan mapping with the Spitzer Space Telescope of a ~1' × 2' area centered on the protostar was carried out. The outflow is imaged in six pure rotational (0-0 S(2) through 0-0 S(7)) H_2 lines, revealing a distinct, S-shaped morphology in all maps. A source map in the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature is presented in which the protostellar envelope appears in absorption. This is the first detection of absorption in the 11.3 μm PAH feature. Spatially resolved excitation analysis of positions in the blue- and redshifted outflow lobes, with extinction-corrections determined from archival Spitzer 8 μm imaging, shows remarkably constant temperatures of ~1000 K in the shocked gas. The radiated luminosity in the observed H_2 transitions is found to be 1.94 ± 0.05 × 10^(–5) L_⊙ in the redshifted lobe and 1.86 ± 0.04 × 10^(–5) L_⊙ in the blueshifted lobe. These values are comparable to the mechanical luminosity of the flow. By contrast, the mass of hot (T ~ 1000 K) H_2 gas is 7.95 ± 0.19 × 10^(–7) M_⊙ in the redshifted lobe and 5.78 ± 0.17 × 10^(–7) M_⊙ in the blueshifted lobe. This is just a tiny fraction, of order 10^(–3), of the gas in the cold (30 K), swept-up gas mass derived from millimeter CO observations. The H_2 ortho/para ratio of 3:1 found at all mapped points in this flow suggests previous passages of shocks through the gas. Comparison of the H_2 data with detailed shock models of Wilgenbus et al. shows the emitting gas is passing through Jump (J-type) shocks. Pre-shock densities of 10^4 cm^(–3)≤ n _H ≤ 10^5 cm^(–3) are inferred for the redshifted lobe and n _H ≤ 10^3 cm^(–3) for the blueshifted lobe. Shock velocities are 5 km s^(–1) ≤ v_s ≤ 10 km s^(–1) for the redshifted gas and v_s = 10 km s^(–1) for the blueshifted gas. Initial transverse (to the shock) magnetic field strengths for the redshifted lobe are in the range 10-32 μG, and just 3 μG for the blueshifted lobe. A cookbook for using the CUBISM contributed software for IRS spectral mapping data is presented in the Appendix

Automated land-use mapping from spacecraft data

The author has identified the following significant results. In response to the need for a faster, more economical means of producing land use maps, this study evaluated the suitability of using ERTS-1 computer compatible tape (CCT) data as a basis for automatic mapping. Significant findings are: (1) automatic classification accuracy greater than 90% is achieved on categories of deep and shallow water, tended grass, rangeland, extractive (bare earth), urban, forest land, and nonforested wet lands; (2) computer-generated printouts by target class provide a quantitative measure of land use; and (3) the generation of map overlays showing land use from ERTS-1 CCTs offers a significant breakthrough in the rate at which land use maps are generated. Rather than uncorrected classified imagery or computer line printer outputs, the processing results in geometrically-corrected computer-driven pen drawing of land categories, drawn on a transparent material at a scale specified by the operator. These map overlays are economically produced and provide an efficient means of rapidly updating maps showing land use

Group Theory in Chemistry

This MQP examines the teaching practices concerning group theory in chemistry and chemistry in group theory at WPI as well as other colleges. The influence and importance of the interaction of the two subjects on each other is exemplified by its prevalence in academic texts as well as a recent research article in the mathematical sciences with applications in chemistry and a recent chemistry experiment, whose analysis used group theory as a tool

Molecular Graph Theory

Graph Theory is a branch of mathematics that has a wealth of applications to other science and engineering disciplines, specifically Chemistry. The primary application of graphs to Chemistry is related to understanding of structure and symmetry at the molecular level. By projecting a molecule to the plane and examining it as a graph, a lot can be learned about the underlying molecular structure of a given compound. Using concepts of Graph Theory this masters project examines the underlying structures of two specific families of compounds, fullerenes and zeolites, from a chemical and mathematical perspective