Engaging Diversity And Marginalization Through Participatory Action Research: A Model For Independent School Reform

Authored by a university researcher, school practitioner, and high school student, this article examines how independent schools can utilize participatory action research (PAR) to bolster diversity and inclusion efforts. A case study approach was taken to showcase a two-year PAR project at a progressive independent school that sought to: (a) enrich institutional knowledge of student diversity, (b) capture the present-day schooling experiences of historically marginalized students in independent school settings, and (c) develop a dynamic action plan to ameliorate school issues that emerged through the PAR inquiry process. Committed to institutional research that informs school policy and practice, we argue that PAR provides a rigorous, student-centered, and democratic model for independent school reform

Far-Field Scattering of a Non-Gaussian Off-Axis Axisymmetric Laser Beam by a Spherical Particle

Experimental laser beam profiles often deviate somewhat from the ideal Gaussian shape of the axisymmetric TEM(00) laser mode. To take these deviations into account when calculating light scattering of an off-axis beam by a spherical particle, we use our phase-modeling method to approximate the beam-shape coefficients in the partial wave expansion of an experimental laser beam. We then use these beam-shape coefficients to compute the near-forward direction scattering of the off-axis beam by the particle. Our results are compared with laboratory data, and we give a physical interpretation of the various features observed in the angular scattering patterns. (C) 1996 Optical Society of Americ

Far-Field Scattering of an Axisymmetric Laser Beam of Arbitrary Profile by an On-Axis Spherical Particle

Experimental laser beam profiles often deviate somewhat from the ideal Gaussian shape of the TEM(00) laser mode. In order to take these deviations into account when calculating light scattering, we propose a method for approximating the beam shape coefficients in the partial wave expansion of an experimental laser beam. We then compute scattering by a single dielectric spherical particle placed on the beam\u27s axis using this method and compare our results to laboratory data. Our model calculations fit the laboratory data well. (C) 1996 Optical Society of Americ

High accuracy CO2_2 line intensities determined from theory and experiment

Atmospheric CO$_2$ concentrations are being closely monitored by remote sensing experiments which rely on knowing line intensities with an uncertainty of 0.5\%\ or better. Most available laboratory measurements have uncertainties much larger than this. We report a joint experimental and theoretical study providing rotation-vibration line intensities with the required accuracy. The {\it ab initio} calculations are extendible to all atmospherically important bands of CO$_2$ and to its isotologues. As such they will form the basis for detailed CO$_2$ spectroscopic line lists for future studies.Comment: 5 pages, 2 figures, 1 tabl

SI-TRACEABLE SCALE FOR MEASUREMENTS OF RADIOCARBON CONCENTRATION

Radiocarbon ($^{14}$C) dating of organic materials is based on measuring the $^{14}$C/$^{12}$C atomic fraction relative to the nascent value that existed when the material was formed by photosynthetic conversion of carbon dioxide present in the atmosphere. This field of measurement has numerous applications including source apportionment of anthropogenic and biogenic fuels and combustion emissions, carbon cycle dynamics, archaeology, and forensics. _x000d_ _x000d_ Accelerator mass spectrometry (AMS) is the most widely used method for radiocarbon detection because it can measure extremely small amounts of radiocarbon (background of nominally 1.2 parts-per-trillion) with high relative precision (0.4 $\%$). AMS measurements of radiocarbon are typically calibrated by reference to standard oxalic-acid (C$_2$H$_2$O$_4$) samples of known radiocativity that are derived from plant matter. Specifically, the internationally accepted absolute dating reference for so-called "modern-equivalent" radiocarbon is 95 $\%$ of the specific radioactivity in AD 1950 of the National Bureau of Standards (NBS) oxalic acid standard reference material and normalized to $\delta^{13}$C$_{VPDB}$ = 19 per mil \footnote{M. Stuiver and H. A. Polach, \textit{Radiocarbon} \textbf{19}, (1977) 355}. With this definition, a "modern-equivalent" corresponds to 1.176(70) parts-per-trillion of $^{14}$C relative to total carbon content._x000d_ _x000d_ As an alternative radiocarbon scale, we propose an SI-traceable method to determine $^{14}$C absolute concentration which is based on linear Beer-Lambert-law absorption measurements of selected $^{14}$C$^{16}$O$_2$ $\nu_3$-band line areas. This approach is attractive because line intensities of chosen radiocarbon dioxide transitions can be determined by $\textit{ab initio}$ calculations with relative uncertainties below 0.5 $\%$. This assumption is justified by the excellent agreement between theoretical values of line intensities and measurements for stable isotopologues of CO$_2$ \footnote{O. L. Polyansky et al., \textit{Phys. Rev. Lett.} \textbf{114}, (2015) 243001}. In the case of cavity ring-down spectroscopy (CRDS) measurements of $^{14}$C$^{16}$O$_2$ peak areas, we show that absolute, SI-traceable concentrations of radiocarbon can be determined through measurements of time, frequency, pressure and temperature. Notably, this approach will not require knowledge of the radiocarbon half-life and is expected to provide a stable scale that does not require an artifact standard

A RIGOROUS COMPARISON OF THEORETICAL AND MEASURED CARBON DIOXIDE LINE INTENSITIES

The ability to calculate molecular line intensities from first principles plays an increasingly important role in populating line-by-line spectroscopic databases because of its generality and extensibility to various isotopologues, spectral ranges and temperature conditions. Such calculations require a spectroscopically determined potential energy surface, and an accurate dipole moment surface that can be either fully $textit{ab initio}$ $footnote{E. Zak et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{177}, (2016) 31.} footnote{Huang et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{130}, (2013) 134.}$ or an effective quantity based on fits to measurements $footnote{Tashkun et al., textit{J. Quant. Spectrosc. Radiat. Transf.} textbf{152}, (2015) 45.}$. Following our recent work where we used high-precision measurements of intensities in the (30013 $rightarrow$00001) band of $^{12}$C$^{16}$O$_2$ to bound the uncertainty of calculated line lists $footnote{Polyansky et al., textit{Phys Rev. Lett.} textbf{114}, (2015) 243001.}$, here we carry out high-precision, frequency-stabilized cavity ring-down spectroscopy measurements in the R-branch of the $^{12}$C$^{16}$O$_2$ (20012 $rightarrow$00001) band from J = 16 to 52. Gas samples consisted of 50 $mu$mol mol$^{-1}$ or 100 $mu$mol mol$^{-1}$ of nitrogen-broadened carbon dioxide with gravimetrically determined SI-traceable molar composition. We demonstrate relative measurement precision (Type A) at the 0.15 $$ level and estimate systematic (Type B) uncertainty contributions in $$ of: isotopic abundance 0.01; sample density, 0.016; cavity free spectral rang,e 0.03; line shape, 0.05; line interferences, 0.05; and carbon dioxide molar fraction, 0.06. Combined in quadrature, these components yield a relative standard uncertainty in measured line intensity less than 0.2 $$ for most observed transitions. These intensities differ by more than 2 $$ from those measured by Fourier transform spectroscopy and archived in HITRAN 2012 but differ by less than 0.5 $$ with the calculations of Zak et al

Experimental Line Parameters of the b^(1)Σ^(+)_g ← X^(3)Σ^(-)_g Band of Oxygen Isotopologues at 760 nm Using Frequency-Stabilized Cavity Ring-Down Spectroscopy

Positions, intensities, self-broadened widths, and collisional narrowing coefficients of the oxygen isotopologues ^(16)O^(18)O, ^(16)O^(17)O, ^(17)O^(18)O, and ^(18)O^(18)O have been measured for the b^(1)Σg + ← X^(3)Σg − (0,0) band using frequency-stabilized cavity ring-down spectroscopy. Line positions of 156 P-branch transitions were referenced against the hyperfine components of the ^(39)K D_1 (4s ^(2)S_(1/2) → 4p ^(2)P_(1/2)) and D_2 (4s ^(2)S_(1/2) → 4p ^(2)P_(3/2)) transitions, yielding precisions of ~0.00005 cm^(−1) and absolute accuracies of 0.00030 cm^(−1) or better. New excited b^(1)Σg + state molecular constants are reported for all four isotopologues. The measured line intensities of the ^(16)O^(18)O isotopologue are within 2% of the values currently assumed in molecular databases. However, the line intensities of the ^(16)O^(17)O isotopologue show a systematic, J-dependent offset between our results and the databases. Self-broadening half-widths for the various isotopologues are internally consistent to within 2%. This is the first comprehensive study of the line intensities and shapes for the ^(17)O^(18)O or ^(18)O_2 isotopologues of the b^(1)Σg + ← X^(3)Σg − (0,0) band of O_2. The ^(16)O_2, ^(16)O^(18)O, and ^(16)O^(17)O line parameters for the oxygen A-band have been extensively revised in the HITRAN 2008 database using results from the present study