RNA’s Thermodynamically Favored Position on Ice

Previous molecular dynamics (MD) work simulated an 8-nucleotide RNA strand on ice, speculatively concluding RNA is stabilized by hydrogen-bonding with the ice’s crystal lattice. That conclusion is investigated by studying a simpler RNA dinucleotide, simulated using GROMACS MD computer simulations. Umbrella sampling results indicate that the most thermodynamically stable position for the RNA to bond is to the uppermost layer of the ice crystal’s basal plane

The temporal structure of oceanic motion off the Oregon coast, northeastern Pacific, 1969

Current measurements collected from an array of moored buoy stations off the coast of Oregon from April through November 1969 have been used to study the spatial and temporal structure of oceanic currents over the continental slope in the northeastern part of the Pacific...

Statistics Of Arctic Cloud Downwelling Infrared Emissivity

Time series of optical depth of Arctic stratus clouds are investigated for scaling properties and biases with respect to a plane-parallel model. The study is based on 3 years of infrared spectrometer and microwave radiometer measurements made at the Atmospheric Radiation Measurement North Slope of Alaska site. Power spectra of radiance and radiance emissivity are found to indicate scaling with a spectral coefficient on the order of 5/3 over 0.5-10 hours, consistent with the Kolmogorov-Obukhov prediction [Kolmogorov, 1941] for three-dimensional turbulence. Irradiance emissivities inferred from the data set, using an independent column approximation and 6-hour time intervals, are further analyzed to find reduction factors for the same mean optical depth in a plane-parallel representation. These factors are estimated to average 0.82 in March and 0.48 in September but with a high degree of variability: The most inhomogeneous quarters of these data sets exhibit reduction factors of 0.57 (March) and 0.20 (September). Observed reduction factors for radiance and irradiance are found to depend primarily on the ratio of mean optical depth to variance, a result consistent with exact results for a gamma distribution of cloud thickness

Unlocking Passion and Setting Students Free: The Impact of Culturally Relevant Writing Instruction in a Middle School English I Classroom

Culturally relevant writing instruction has the potential to validate the voices of students often not heard. Documented disparities in student writing proficiency in grades K-12 indicate a pressing need to employ more effective approaches in facilitating writing instruction. This paper presents the findings of a mixed methods research study that explored eighth grade English I students’ middle school reading and writing preferences, writing experiences, and the impact of culturally relevant writing instruction. Data were gathered from 63 students via reflective journals, writing interest forms, learning logs, and writing artifacts collected throughout a 3-week writing unit. Our findings reveal that writing instruction that leverages students’ interests, experiences, and cultural background has the potential to increase learning outcomes for students

A responsitivity-based criterion for accurate calibration of FTIR spectra: theoretical development and bandwidth estimation

An analytical expression for the variance of the radiance measured by Fourier-transform infrared (FTIR) emission spectrometers exists only in the limit of low noise. Outside this limit, the variance needs to be calculated numerically. In addition, a criterion for low noise is needed to identify properly calibrated radiances and optimize the instrument bandwidth. In this work, the variance and the magnitude of a noise-dependent spectral bias are calculated as a function of the system responsivity (r) and the noise level in its estimate (? r ). The criterion ? r /

A master\u27s recital in flute

Natalie Neshyba presented a graduate flute recital on Friday, March 6th, 2015 at 6:00 pm in Davis Hall of the Gallagher‐Bluedorn Performing Arts Center at the University of Northern Iowa. This recital was given in partial fulfillment of the requirements for a Master of Music degree in flute performance. Dr. Polina Khatsko, pianist, performed alongside Ms. Neshyba on two selections. The program began with an unaccompanied work, Les Folies d’Espagne, by Marin Marais. Next on the program was Claude Debussy’s Sonata in G minor L140 for flute and piano, which was recently transcribed from the original violin version by Dr. Claudia Anderson and SoYoung Lee. The second half of the recital opened with two movements of André Jolivet’s powerful solo flute work Cinq Incantations. To close the recital, Ms. Neshyba and Dr. Khatsko performed the two‐movement Sonata for Flute and Piano Op. 23, composed by Lowell Liebermann, offering a dynamic and dramatic finish. This program showcased a variety of challenging repertoire requiring solid technical facility, contrasting tone color, and knowledge of appropriate style representative of a graduate level recital

Scanning electron microscopy and molecular dynamics of surfaces of growing and ablating hexagonal ice crystals

We present the first clearly resolved observations of surfaces of growing and ablating hexagonal ice crystals using variable-pressure scanning electron microscopy. The ice surface develops trans-prismatic strands, separated from one another by distances of 5–10 ?m. The strands are present at a wide range of supersaturations, but are most pronounced at temperatures near the frost point. Pyramidal facets consistent with Miller-Bravais indices of 1011, and possibly also 2021, are associated with ice growth under these conditions. A molecular-dynamics model of a free-standing ice Ih nanocolumn containing 8400 water molecules does not develop trans-prismatic strands, suggesting these features originate at larger spatial or temporal scales. The possible relevance of these surface features to cirrus ice is discussed

Representation Of A Nonspherical Ice Particle By A Collection Of Independent Spheres For Scattering And Absorption Of Radiation: 2. Hexagonal Columns And Plates

[1] A cloud of nonspherical ice particles may be represented in radiation models by a collection of spheres, in which the model cloud contains the same total volume of ice and the same total surface area as the real cloud but not the same number of particles. The spheres then have the same volume-to-area (V/A) ratio as the nonspherical particle. In previous work this approach was shown to work well to represent randomly oriented infinitely long circular cylinders for computation of hemispherical reflectance, transmittance, and absorptance. In this paper the results have been extended to hexagonal columns and plates using a geometric optics technique for large particles and finite-difference-time-domain theory (FDTD) for small particles. The extinction efficiency and single-scattering coalbedo for these prisms are closely approximated by the values for equal-V/A spheres across the ultraviolet, visible, and infrared from 0.2 to 25 mum wavelength. Errors in the asymmetry factor can be significant where ice absorptance is weak, at visible wavelengths for example. These errors are greatest for prisms with aspect ratios close to 1. Errors in hemispheric reflectance, absorptance, and transmittance are calculated for horizontally homogeneous clouds with ice water paths from 0.4 to 200,000 g m(-2) and crystal thicknesses of 1 to 400 mum, to cover the range of crystal sizes and optical depths from polar stratospheric clouds (PSCs) through cirrus clouds to surface snow. The errors are less than 0.05 over most of these ranges at all wavelengths but can be larger at visible wavelengths because of the ideal shapes of the prisms. The method was not tested for, and is not expected to be accurate for, angle-dependent radiances

Responsivity-based Criterion For Accurate Calibration Of Ftir Emission Spectra: Theoretical Development And Bandwidth Estimation

An analytical expression for the variance of the radiance measured by Fourier-transform infrared (FTIR) emission spectrometers exists only in the limit of low noise. Outside this limit, the variance needs to be calculated numerically. In addition, a criterion for low noise is needed to identify properly calibrated radiances and optimize the instrument bandwidth. In this work, the variance and the magnitude of a noise-dependent spectral bias are calculated as a function of the system responsivity (r) and the noise level in its estimate (sigma(r)). The criterion sigma(r)/r \u3c 0.3, applied to downwelling and upwelling FTIR emission spectra, shows that the instrument bandwidth is specified properly for one instrument but needs to be restricted for another

Representation Of A Nonspherical Ice Particle By A Collection Of Independent Spheres For Scattering And Absorption Of Radiation: 3. Hollow Columns And Plates

The ability of an assembly of spheres to represent scattering and absorption by a nonspherical ice crystal of the same volume-to-area (V/A) ratio was previously evaluated for convex shapes (circular cylinders and hexagonal prisms). Here we extend the comparison to indented and hollow prisms, which are common in ice clouds. In the equivalent-sphere representation, the crystal mass and surface area are both conserved. Internal surfaces as well as external surfaces contribute to the total surface area; in the model representation both become external surfaces of spheres. The optical depth tau of the model cloud is thus greater than that of the real cloud by the ratio A/4P, where A is the total area of the nonspherical particle and P is the orientation-averaged projected area. This ratio, which we call fluffiness,\u27\u27 is unity for convex shapes but may exceed 2 for clusters of hollow bullets. In effect, the scattering at interior surfaces of a hollow crystal becomes classified as multiple scattering in the model of ice spheres. Therefore, rather than directly comparing the asymmetry factor (g) and single-scattering albedo (omega(o)) of the hollow crystal to those of the equal-V/A sphere, it is more appropriate to compare the product tau(1 - g)omega(o), because this quantity largely determines the bulk radiative properties of the cloud. Errors in albedo, absorptance, and transmittance of ice clouds, caused by the equal-V/A representation, are presented for a range of aspect ratios, indentation depths, and ice-water paths at visible and near-infrared wavelengths