Elementary Science and Language Arts: Should We Blur the Boundaries?

Elementary school goals for instruction focus on developing literate readers and writers. It has been recommended that language arts strategies can help elementary teachers more effectively teach science. The terms “integrated, interdisciplinary, and thematic instruction” are defined and examples are given for using each in an elementary classroom. Definitions are provided comparing language arts and scientific literacy. Use of thematic instruction with an interdisciplinary focus is recommended to help meet both language arts and science goals and objectives as they relate to the National Science Education Standards and the National English Language Arts Standards. Recommendations are made for helping teachers effectively use language arts strategies to help develop science literacy, and science to provide purpose for reading and writing activities within thematic, interdisciplinary instruction often found in elementary schools.     

Geometry of the copositive and completely positive cones

The copositive cone, and its dual the completely positive cone, have useful applications in optimisation, however telling if a general matrix is in the copositive cone is a co-NP-complete problem. In this paper we analyse some of the geometry of these cones. We discuss a way of representing all the maximal faces of the copositive cone along with a simple equation for the dimension of each one. In doing this we show that the copositive cone has faces which are isomorphic to positive semidefinite cones. We also look at some maximal faces of the completely positive cone and find their dimensions. Additionally we consider extreme rays of the copositive and completely positive cones and show that every extreme ray of the completely positive cone is also an exposed ray, but the copositive cone has extreme rays which are not exposed rays.     

The flexural vibration of welded rectangular plates

A theoretical and experimental study of the effect of weld runs on the flexural vibrational characteristics of the common structural element, the rectangular plate, is described. A finite difference technique is utilized for the determination of the in-plane residual stress pattern due to the weld(s) and the Rayleigh-Ritz method, with beam characteristic functions, is used for the out-of-plane vibration analysis. The theoretical approach presented is applicable to rectangular plates of any practical aspect ratio, having any combination of out-of-plane boundary conditions for which beam functions may reasonably be used and subject to one or more weld runs parallel to any edge. Theoretical and experimental results for a number of specific plates are presented, demonstrating the effects of welding on the plate vibration and the capability and accuracy of the analytical approach in predicting these effects. Included is a study of the effect of using the full residual stress pattern as derived from the finite difference analysis, the effect of neglecting certain stress components and the effect of using simplified stress patterns developed primarily for the stress and buckling analysis of long plates.     

Critical adjustment of correlation filters for optical character recognition

As yet, optical correlation filters were not applied successfully in commercially available equipment since 1964. Since Vander Lugt¹ prepared the first correlation filter using a Mach Zender interferometer a considerable amount of effort both experimental and theoretical was devoted to them.

In this paper an attempt will be made to evaluate their usefulness in optical character recognition on the basis of our experimental work. No attempt will be made to survey other work in this field.

For the sake of completeness a brief outline of the theory will be given.     

Local compositional fluctuations in PPO/HIPSand PPO/SBS blends

Solid-state NMR relaxation has been used to explore the distribution of components in poly(phenylene oxide) (PPO) high impact polystyrene (HIPS) and PPO/poly(styrene-b-butadiene-b-styrene) (SBS) blends. The nuclear relaxation of PPO in the former system is single exponential for all compositions, but the relaxation of PS in the blend is simple exponential only when the PPO content is low but is otherwise nonexponential. The nuclear magnetization decay curves were analyzed in terms of statistical compositional fluctuation at the scale of spin diffusion distances of several nm. Distribution functions for nuclear relaxation and for blend composition have been derived. Extraction of low molecular weight occluded PS from HIPS resulted in blends having reduced homogeneity. Addition of low molecular weight PS enhanced homogeneity in both the PPO/HIPS and PPO/SBS blends. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of osmium(II) trispyrazolylborate complexes

Treatment of H2OsBr6 with excess 1,5-cyclooctadiene (cod) in boiling tert-butyl alcohol affords the polymer [OsBr2(cod)]x (1), which reacts with acetonitrile to form the mononuclear adduct OsBr2(cod)(CH3CN)2 (2). Polymer 1 reacts with potassium trispyrazolylborate (KTp) in ethanol to afford the hydride TpOs(cod)H (3) and the bromide complex TpOs(cod)Br (4). Bromide complex 4 reacts with sodium methoxide in methanol to afford TpOs(cod)OMe (5), which has been structurally characterized. Treatment of hydride 3 with methyl trifluoromethanesulfonate (MeOTf) in diethyl ether results in loss of methane and formation of the triflate complex TpOs(cod)OTf (6), which reacts with MgMe2 to give the methyl complex TpOs(cod)Me (7). The addition of bis(dimethylphosphino)methane (dmpm) to the known compound TpOs(PPh3)2Cl yields a mixture of the substitution products TpOs(eta1-dmpm)(PPh3)Cl (8) and TpOs(eta2-dmpm)Cl (9); the latter reacts with methyllithium to generate the methyl compound TpOs(dmpm)Me (10). NMR and IR data for these new compounds are reported. Crystal data for 5.MeOH at -80 degrees C are as follows: monoclinic, P2(1)/n, a = 10.728(1) A, b = 14.004(2) A, c = 13.906(2) A, beta = 102.42(6) degrees , V = 2040.3(5) A3, Z = 4, R(F) = 0.0247 for I > or = 2sigma(I), and R(wF2) = 0.0539 for all data.     

A new approximation for atom-diatom rotational-relaxation cross sections

A semiclassical approximation to the S matrix of the infinite-order-sudden approximation is introduced. This is employed to yield for the energy-transfer effective cross section a purely classical approximation, analogous to the Mason-Monchick approximation [J. Chem. Phys. 36, 1622 (1962)] for traditional collision integrals. Constraints on energy and on angular momentum transfer are included. Numerical evaluation of this new approximation can readily be performed alongside that for traditional collision integrals. The new result is tested against full classical trajectory calculations for six potential energy surfaces for the collision systems H-N(2), He-N(2), He-CO, and Ar-CO(2). Differences of no more than 15% from the classical trajectory calculations have been obtained.     

Stabilization of carbon dioxide-in-water emulsions by proteins

At CO2 pressures between 40 and 100 bar, we have succeeded in creating very stable carbon dioxide-in-water emulsions using a relatively inexpensive and innocuous protein (principally beta-lactoglobulin) as the sole emulsifying agent.     

Synthesis, characterization, and X-ray crystal structure of the octabromodiosmate(III) salt [(C5Me4H)2OsBr]2[Os2Br8] and its conversion to [(C5Me4H)2OsBr][Os2HBr4(cod)2]

Treatment of hexabromoosmic acid, H₂OsBr₆, with 4 equiv. of tetramethylcyclopentadiene (C₅Me₄H₂) in tert-butanol at reflux for 8 h affords the unusual salt [(C₅Me₄H)₂OsBr]₂[Os₂Br₈], 1, which is the bis(tetramethylcyclopentadienyl)bromoosmocinium(IV) salt of the octabromodiosmate(III) dianion. The brown color of the salt suggests that the anion adopts an eclipsed conformation (D_4h symmetry) and this conclusion has been confirmed by a single-crystal X-ray diffraction experiment. The X-ray crystal structure indicates that the osmium atoms in the anion are disordered over two sites. The bromine atoms show no evidence of disorder and are disposed in a quasi-cubic arrangement; the two Os-Os vectors are almost exactly orthogonal to each other and each vector points toward a different pair of opposite square faces of the Br₈ cube. The Os-Os bond distances are 2.219(5) and 2.229(1) Å; the average Os-Br distance in the anion is 2.417(2) Å. Treatment of [(C₅Me₄H)₂OsBr]₂[Os₂Br₈] with excess 1,5-cyclooctadiene in ethanol at gentle reflux for 3 h affords [(C₅Me₄H)₂OsBr][Os₂HBr₄(cod)₂], 2. An X-ray crystallographic study was carried out on a sample in which the cation was a mixture of [(C₅Me₄H)₂OsBr⁺] and [(C₅Me₄H)₂OsH⁺]. The results demonstrate that the anion adopts a confacial bioctahedral structure in which the hydride ligand and two bromides bridge between the two osmium centers. The CC bonds of the cod ligands are trans to the bridging bromide groups. The Os-Os bond distance in the anion is 2.874(1) Å. The average Os-Br distance is 2.596(2) Å for the bridging bromides and 2.565(2) Å for the terminal bromides. Compound 2 is the first example of an anionic diosmium complex containing a bridging hydride. The reaction of 1 with cod also results in the formation of bis(tetramethylcyclopentadienyl)osmocene, (C₅Me₄H)₂Os, 3, which has been isolated and characterized. Treatment of (C₅Me₄H)₂Os with 1.0 equiv. of HBF₄ · Et₂O affords the osmocinium salt [(C₅Me₄H)₂OsH][BF₄].