1,025 research outputs found
Alternative model for the administration and analysis of research-based assessments
Research-based assessments represent a valuable tool for both instructors and
researchers interested in improving undergraduate physics education. However,
the historical model for disseminating and propagating conceptual and
attitudinal assessments developed by the physics education research (PER)
community has not resulted in widespread adoption of these assessments within
the broader community of physics instructors. Within this historical model,
assessment developers create high quality, validated assessments, make them
available for a wide range of instructors to use, and provide minimal (if any)
support to assist with administration or analysis of the results. Here, we
present and discuss an alternative model for assessment dissemination, which is
characterized by centralized data collection and analysis. This model provides
a greater degree of support for both researchers and instructors in order to
more explicitly support adoption of research-based assessments. Specifically,
we describe our experiences developing a centralized, automated system for an
attitudinal assessment we previously created to examine students'
epistemologies and expectations about experimental physics. This system
provides a proof-of-concept that we use to discuss the advantages associated
with centralized administration and data collection for research-based
assessments in PER. We also discuss the challenges that we encountered while
developing, maintaining, and automating this system. Ultimately, we argue that
centralized administration and data collection for standardized assessments is
a viable and potentially advantageous alternative to the default model
characterized by decentralized administration and analysis. Moreover, with the
help of online administration and automation, this model can support the
long-term sustainability of centralized assessment systems.Comment: 7 pages, 1 figure, accepted in Phys. Rev. PE
The OH-F substitution in synthetic pargasite at 1.5 kbar, 850 °C.
Amphiboles were synthesized at 1.5 kbar PH2O and 850 °C along the join pargasite-fluoropargasite. Structural variations in the amphibole as a function of F have been characterized by a combination of SEM-EDS, X-ray powder diffraction, and infrared spectroscopy. SEM-EDS analyses show that, for increasing F in the system, there is a decrease in Altot in the amphibole and a significant decrease of F incorporation in the structure. In agreement with the EDS data, the variation in cell parameters and IR spectra show that incorporation of F in pargasite is restricted to about 1.0 atoms per formula unit (apfu). The OH-stretching spectra show fine structure caused by F replacing OH at the O3 anion site, and are consistent with two-mode behavior typical of A-site-filled amphiboles. The agreement between calculated and observed relative band intensities suggests complete short-range disorder of OH and F at the O3 anion site
FIRE Cirrus on October 28, 1986: LANDSAT; ER-2; King Air; theory
A simultaneous examination was conducted of cirrus clouds in the FIRE Cirrus IFO-I on 10/28/86 using a multitude of remote sensing and in-situ measurements. The focus is cirrus cloud radiative properties and their relationship to cloud microphysics. A key element is the comparison of radiative transfer model calculations and varying measured cirrus radiative properties (emissivity, reflectance vs. wavelength, reflectance vs. viewing angle). As the number of simultaneously measured cloud radiative properties and physical properties increases, more sharply focused tests of theoretical models are possible
Site occupancies in synthetic monoclinic amphiboles: Rietveld structure refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite.
Amphiboles were synthesized at 750 8C, 1 kbar (H2O) on the binary joins (nickel, magnesium)-richterite and (magnesium, cobalt)-richterite. Structural variations and site occupancies were characterized by Rietveld structure refinement, with final RBragg indices in the range 4–9%, and by powder infrared spectroscopy in the principal OH-stretching region. Site-occupancy refinement of Ni-Mg and Mg-Co distributions give the partition coefficients over M1,3 and M2 where KM21 5 (M21/Mg)M1,3/(M21/Mg)M2, and M21 5 Ni21 or Co21, K 5 2.98 6 0.37 and K 5 1.34 6 0.31. Both Kd Ni Co values are greater than 1.0, d d whereas [6]r(Ni21 ) , [6]r(Mg) , [6]r(Co21 ); this indicates that cation size is not the primary factor affecting the ordering of Ni-Mg and Mg-Co over the octahedral sites. The infrared spectra of intermediate binary compositions show fine structure caused by ordering of Ni- Mg or Mg-Co over the M1,3 sites and by ordering of Na and M (vacancy) at the A site; thus intermediate compositions show an eight-band spectrum in the principal OHstretching region. Precise band intensities were derived by nonlinear least-squares fitting of Gaussian band shapes to the observed spectra. The relative observed intensities of the combinations of bands 3IA1 2IB1 IC and IB 1 2IC 1 3ID are in accord with the equations o o o o o o of Burns and Strens (1966), indicating that there is no significant variation in molar absorptivity with frequency (energy) for individual bands within a single sample (spectrum). Combined with the results of Skogby and Rossman (1991) on polarized single-crystal infrared spectra of amphiboles, this result suggests that different local configurations of M1,3 cations in amphiboles couple such that the transition probabilities of the associated OH groups are equal
A 2-pyridone-amide inhibitor targets the glucose metabolism pathway of Chlamydia trachomatis.
UnlabelledIn a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection.ImportanceChlamydia trachomatis is a bacterial pathogen of humans that causes a common sexually transmitted disease as well as eye infections. It grows only inside cells of its host organism, within a parasitophorous vacuole termed the inclusion. Little is known, however, about what bacterial components and processes are important for C. trachomatis cellular infectivity. Here, by using a visual screen for compounds that affect bacterial distribution within the chlamydial inclusion, we identified the inhibitor KSK120. As hypothesized, the altered bacterial distribution induced by KSK120 correlated with a block in C. trachomatis infectivity. Our data suggest that the compound targets the glucose-6-phosphate (G-6P) metabolism pathway of C. trachomatis, supporting previous indications that G-6P metabolism is critical for C. trachomatis infectivity. Thus, KSK120 may be a useful tool to study chlamydial glucose metabolism and has the potential to be used in the treatment of C. trachomatis infections
The 27-28 October 1986 FIRE IFO cirrus case study: Comparison of satellite and aircraft derived particle size
Theoretical calculations predict that cloud reflectance in near infrared windows such as those at 1.6 and 2.2 microns should give lower reflectances than at visible wavelengths. The reason for this difference is that ice and liquid water show significant absorption at those wavelengths, in contrast to the nearly conservative scattering at wavelengths shorter than 1 micron. In addition, because the amount of absorption scales with the path length of radiation through the particle, increasing cloud particle size should lead to decreasing reflectances at 1.6 and 2.2 microns. Measurements at these wavelengths to date, however, have often given unpredicted results. Twomey and Cocks found unexpectedly high absorption (factors of 3 to 5) in optically thick liquid water clouds. Curran and Wu found expectedly low absorption in optically thick high clouds, and postulated the existence of supercooled small water droplets in place of the expected large ice particles. The implications of the FIRE data for optically thin cirrus are examined
The 27-28 October 1986 FIRE IFO Cirrus case study: Comparison of radiative transfer theory with observations by satellite and aircraft
Observations of cirrus and altocumulus clouds during the First International Satellite Cloud Climatology Project Regional Experiment (FIRE) are compared to theoretical models of cloud radiative properties. Three tests are performed. First, LANDSAT radiances are used to compare the relationship between nadir reflectance ot 0.83 micron and beam emittance at 11.5 microns with that predicted for model calculations using spherical and nonspherical phase functions. Good agreement is found between observations and theory when water droplets dominate. Poor agreement is found when ice particles dominate, especially using scattering phase functions for spherical particles. Even when compared to a laboratory measured ice particle phase function, the observations show increased side scattered radiation relative to the theoretical calculations. Second, the anisotropy of conservatively scattered radiation is examined using simultaneous multiple angle views of the cirrus from LANDSAT and ER-2 aircraft radiometers. Observed anisotropy gives good agreement with theoretical calculations using the laboratory measured ice particle phase function and poor agreement with a spherical particle phase function. Third, Landsat radiances at 0.83, 1.65, and 2.21 microns are used to infer particle phase and particle size. For water droplets, good agreement is found with King Air FSSP particle probe measurements in the cloud. For ice particles, the LANDSAT radiance observations predict an effective radius of 60 microns versus aircraft observations of about 200 microns. It is suggested that this descrepancy may be explained by uncertainty in the imaginary index of ice and by inadequate measurements of small ice particles by microphysical probes
Subsidizing Religious Participation through Groups: A Model of the “Megachurch” Strategy for Growth
Either despite or because of their non-traditional approach, megachurches have grown significantly in the United States since 1980. This paper models religious participation as an imperfect public good which, absent intervention, yields suboptimal participation by members from the church’s perspective. Megachurches address this problem in part by employing secular-based group activities to subsidize religious participation that then translates into an increase in the attendees’ religious investment. This strategy not only allows megachurches to attract and retain new members when many traditional churches are losing members but also results in higher levels of an individual’s religious capital. As a result, the megachurch may raise expectations of members’ levels of commitment and faith practices. Data from the FACT2000 survey provide evidence that megachurches employ groups more extensively than other churches, and this approach is consistent with a strategy to use groups to help subsidize individuals’ religious investment. Religious capital rises among members of megachurches relative to members of non-megachurches as a result of this strategy
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