946 research outputs found

    Embedded librarianship and problem-based learning in undergraduate mathematics courses

    Get PDF
    A pedagogical approach of problem-based learning with embedded librarianship in several undergraduate mathematics courses is implemented in this educational research. The students are assigned to work on several projects on various applications of mathematical topics in daily life and submit written reports. An embedded librarian collaborates together with the instructor and the students to improve the students' information literacy. Initial reaction and anecdotal evidence show that the students' information literacy and academic performance have improved throughout the semesters.Comment: 4 pages, 2 tables, International Congress of Women Mathematicians Presentation Book, Ewha Womans University, Seoul, South Korea, pp. 117-120, 201

    A Comparative Study of the Mechanics of Flying and Swimming in Some Common Brown Bats

    Get PDF
    Author Institution: Central State College, Wilberforce, Ohi

    The Landscape Ecology of Western Forest Fire Regimes

    Get PDF
    Fire has had a major role in shaping the forested landscapes of the American West. In recent decades, major efforts to quantify that role have been made, and characteristics of historic fire regimes have been defined: frequency, magnitude, variability, seasonality, synergism, and extent. Together, these characteristics also defined the historic landscape effects of fire in low-, moderate-, and high-severity fire regimes. Coarse-filter conservation strategies typically rely on knowledge of natural disturbance regimes to define appropriate forest structure goals, both at the stand and landscape scale, and these will differ by fire regime. Historic patch size increased across low- to high-severity spectrum, but edge was maximized in the moderate-severity fire regime. Fire exclusion in the 20th century has caused two major types of landscape change: loss of openings in once patchy landscapes, and imposition of high-severity landscape dynamics in areas where wildfire that escape suppression now burn. Effects of historical fire regimes may be in some cases either difficult to mimic or undesirable

    Northwest Africa 8159: An approximately 2.3 Billion Year Old Martian Olivine-Bearing Augite Basalt

    Get PDF
    Based on petrology, mineralogy, and bulk composition, the new NWA 8159 martian meteorite is distinct from all known samples from Mars. In particular, the augite compositional trends are unique, but most similar to those of nakhite intercumulus. Whether NWA 8159 represents a new lithology or is related to a known meteorite group remains to be determined. Sr and Nd isotopic analyses will allow comparison of source characteristics with SNC and other new ungrouped meteorites (e.g., NWA 7635). Here we report initial Rb-Sr and Sm-Nd isotopic results for NWA 8159 with the objective to determine its formation age and to potentially identify similarities and potential source affinities with other martian rocks

    Sm-Nd and Rb-Sr Isotopic Systematics of a Heavily Shocked Martian Meteorite Tissint and Petrogenesis of Depleted Shergottites

    Get PDF
    Tissint is a very fresh Martian meteorite that fell near the town of Tissint in Morocco on July 18, 2011. It contains abundant olivine megacrysts (~23%) in a fine-grained matrix of pyroxene (~55%), maskelynitized plagioclase (~15%), opaques (~4%) and melt pockets (~3%) and is petrographically similar to lithologies A and C of picritic shergottite EETA 79001 [1,2]. The presence of 2 types of shock-induced glasses and all 7 high-pressure mineral phases that were ever found in melt pockets of Martian meteorites suggests it underwent an intensive shock metamorphism of ~25 GPa and ~2000 C localized in melt pockets [2]. Mineral textures suggest that olivines, pyroxenes and plagioclases probably did not experience such hightemperature. Earlier determinations of its age yielded 596+/-23 Ma [3] and 616+/-67 Ma [4], respectively, for the Sm-Nd system and 583+/-86 Ma for the Lu-Hf system [4], in agreement with the 575+/-18 Ma age of the oldest olivine-phyric depleted shergottite Dho 019 [5]. However, the exposure ages of Tissint (~1 Ma [1, 6, 7]) and Dho 019 (~20 Ma [8]) are very different requiring two separate ejection events. These previously determined Sm-Nd and Lu-Hf ages are older than the Ar-Ar maskelynite plateau age of 524+/-15 Ma [9], reversing the pattern usually observed for Martian meteorites. In order to clarify these age issues and place models for Tissint's petrogenesis on a firm basis, we present new Rb-Sr and Sm- Nd isotopic results for Tissint, and discuss (a) the shock effects on them and the Ar-Ar chronometer, (b) correlation of the determined ages with those of other depleted shergottites, and (c) the petrogenesis of depleted shergottites. Since the meteorite is a recent fall, terrestrial contamination is expected to be minimal, but, the strong shock metamorphism might be expected to compromise the equilibrium of the isotopic systems

    Methods to Obtain the Occupant Perspective

    Get PDF
    This chapter summarizes the most important methods for actively engaging occupants in the processes of designing buildings. Each stage in the building life cycle places different demands on the professional-to-occupant relationship. Both objective and subjective data are important in this relationship and raises key epistemological questions about factors that cannot be directly observed—e.g., how do we know what we know about occupant behavior? The chapter guides the reader through this intellectually dangerous terrain by suggesting that the best way to find out what people think is to ask them. Some methods discussed here are familiar to practitioners, including interviews, surveys, focus groups, and direct observation. Others are just entering widespread practice, including virtual reality simulations, ubiquitous sensors and monitoring systems, and momentary ecological assessments. Each method has strengths, weaknesses, and appropriateness for use during certain stages of the building life cycle. The key takeaways from this chapter are that (1) building designers and operators can learn much value from occupants and (2) the new skills needed to engage successfully can be quickly learned. Occupant-centric design approaches that employ these methods improve the likelihood of successful building, interface design, and occupant outcomes

    Synchronous reluctance machine with controlled capacitance injection

    Get PDF
    Abstract This paper describes a detailed analysis, verified by practical experimental results, of a synchronous reluctance machine with two similar stator windings and capacitance injection using a static switch. The steady state equivalent circuit is developed and used to investigate leading capacitance injection into the machine via a balanced three phase auxiliary winding that is only magnetically coupled to the main winding. The scheme was found to improve the torque and power factor performance of the machine as well as reduce harmonics in the line current. Two switching topologies were utilized for the static control in this arrangement, and both were found to present good and comparable results. Experimental results corroborate the simulations

    Influence of Fires, Fungi and Mountain Pine Beetles on Development of a Lodgepole Pine Forest in South-Central Oregon

    Get PDF
    Virtually pure lodgepole pine stands form an edaphic climax community over large areas of the infertile pumice plateau of south-central Oregon. During our ongoing studies on the dynamics of these forest we developed the scenario that periodic fires create fungal infection courts in damaged roots; in time, advanced decay develops in the butts and stems of these trees. The mountain pine beetle preferentially selects and kills these trees during the flight season. As these outbreaks develop, additional uninfected trees are attacked. In time, the stage is set for subsequent fires as needles drop, snags fall, and logs decay

    Reassessing the Formation of CK7 Northwest Africa (NWA) 8186

    Get PDF
    The classification of meteorites is commonly determined using isotopes, modal mineralogy, and bulk compositions [1]. Bulk rare earth elements (REEs) in meteorites are additionally utilized to understand parent body processes. Numerous authors have shown that chondritic groups exhibit REE patterns that may be attributable to their parent bodies [e.g. 2-4], and variations in abundances and concentrations of REEs may reflect early nebular processes, thermal metamorphism, and aqueous alteration on the parent body [5-6]

    Hydrogen Isotopic Composition of Apatite in Northwest Africa 7034: A Record of the "Intermediate" H-Isotopic Reservoir in the Martian Crust?

    Get PDF
    Northwest Africa (NWA) 7034 and its pairings comprise a regolith breccia with a basaltic bulk composition [1] that yields a better match than any other martian meteorite to visible-infrared reflectance spectra of the martian surface measured from orbit [2]. The composition of the fine-grained matrix within NWA 7034 bears a striking resemblance to the major element composition estimated for the martian crust, with several exceptions. The NWA 7034 matrix is depleted in Fe, Ti, and Cr and enriched in Al, Na, and P [3]. The differences in Al and Fe are the most substantial, but the Fe content of NWA 7034 matrix falls within the range reported for the southern highlands crust [6]. It was previously suggested by [4] that NWA 7034 was sourced from the southern highlands based on the ancient 4.4 Ga ages recorded in NWA 7034/7533 zircons [4, 5]. In addition, the NWA 7034 matrix material is enriched in incompatible trace elements by a factor of 1.2-1.5 [7] relative to estimates of the bulk martian crust. The La/Yb ratio of the bulk martian crust is estimated to be approximately 3 [7], and the La/Yb of the NWA 7034 matrix materials ranges from approximately 3.9 to 4.4 [3, 8], indicating a higher degree of LREE enrichment in the NWA 7034 matrix materials. This elevated La/Yb ratio and enrichment in incompatible lithophile trace elements is consistent with NWA 7034 representing a more geochemically enriched crustal terrain than is represented by the bulk martian crust, which would be expected if NWA 7034 represents the bulk crust from the southern highlands. Given the similarities between NWA 7034 and the martian crust, NWA 7034 may represent an important sample for constraining the composition of the martian crust, particularly the ancient highlands. In the present study, we seek to constrain the H isotopic composition of the martian crust using Cl-rich apatite in NWA 7034. Usui et al., [9] recently proposed that a H isotopic reservoir exists within the martian crust that has a H-isotopic composition that is intermediate (D of 1000-2000per mille) between an isotopically light mantle (Delta D is less than 275per mille [10]) and an isotopically heavy atmosphere (D of 2500-6100per mille [11, 12]). Apatites in NWA 7034 occur in a number of lithologic domains, however apatites across all lithologic domains have been affected by a Pb-loss event at about 1.5 Ga before present [5], so they are unlikely to have retained a primary composition and are more likely to have equilibrated with fluids within the martian crust that may or may not have exchanged with the martian atmosphere. Equilibration of apatite with crustal fluids is further supported by the chlorine-rich compositions exhibited by apatites in NWA 7034 in comparison to apatites from other martian meteorites (Figure 1; [13]). Cl is more hydrophilic than F, which promotes formation of Cl-rich apatite compositions in fluid-rich systems [e.g., 14, 15-17]
    corecore