Introduction to the GiNaC Framework for Symbolic Computation within the C++ Programming Language

The traditional split-up into a low level language and a high level language in the design of computer algebra systems may become obsolete with the advent of more versatile computer languages. We describe GiNaC, a special-purpose system that deliberately denies the need for such a distinction. It is entirely written in C++ and the user can interact with it directly in that language. It was designed to provide efficient handling of multivariate polynomials, algebras and special functions that are needed for loop calculations in theoretical quantum field theory. It also bears some potential to become a more general purpose symbolic package

The Spectrum Characteristic of Hydrogen Bonds

It has been observed that in certain substances containing hydroxyl hydrogen the relatively narrow and intense absorption bands which ordinarily are characteristic of the O-H group appear to be absent. Since in these cases it appears very probable that the hydroxyl hydrogen is involved in the formation of the type of linkage known as the "hydrogen bond" it has been suggested that the absence of bands may be taken as a criterion for the presence of such bond (1). On the other hand the O-H fundamental band appears strongly in a number of substances containing hydroxyl groups in which the hydrogens are supposed to be engaged in linkages which Bernal and Megal prefer, in this case, to call "hydroxyl bonds" (2). These substances include ice and a number of minerals examined by Coblentz (3). These observations have left the situation somewhat unclear since they leave the question open as to whether the O-H absorption in the cases first mentioned has merely shifted to some new region where it has not been observed, or whether it has really disappeared. If the latter were true there would appear to be a considerable difference between the hydrogen linkages in the two cases

Natural flow wing

The invention is a natural flow wing and a method for constructing the same. The method comprises contouring a three-dimensional upper surface and a three-dimensional lower surface of the natural flow wing independently of one another into a prescribed shape. Experimental data and theoretical analysis show that flow and pressure-loading over an upper surface of a wing tend to be conical about an apex of the wing, producing favorable and unfavorable regions of performance based on drag. The method reduces these unfavorable regions by shaping the upper surface such that the maximum thickness near a tip of the natural flow wing moves aft, thereby, contouring the wing to coincide more closely with the conical nature of the flow on the upper surface. Nearly constant compressive loading characterizes the flow field over a lower surface of the conventional wing. Magnitude of these compressive pressures on the lower surface depends on angle of attack and on a streamwise curvature of the lower surface of the wing and not on a cross-sectional spanwise curvature. The method, thereby, shapes the lower surface to create an area as large as possible with negative slopes. Any type of swept wing may be used to obtain the final, shaped geometry of the upper and lower surfaces of the natural flow wing

The natural flow wing-design concept

A wing-design study was conducted on a 65 degree swept leading-edge delta wing in which the wing geometry was modified to take advantage of the naturally occurring flow that forms over a slender wing in a supersonic flow field. Three-dimensional nonlinear analysis methods were used in the study which was divided into three parts: preliminary design, initial design, and final design. In the preliminary design, the wing planform, the design conditions, and the near-conical wing-design concept were derived, and a baseline standard wing (conventional airfoil distribution) and a baseline near-conical wing were chosen. During the initial analysis, a full-potential flow solver was employed to determine the aerodynamic characteristics of the baseline standard delta wing and to investigate modifications to the airfoil thickness, leading-edge radius, airfoil maximum-thickness position, and wing upper to lower surface asymmetry on the baseline near-conical wing. The final design employed an Euler solver to analyze the best wing configurations found in the initial design and to extend the study of wing asymmetry to develop a more refined wing. Benefits resulting from each modification are discussed, and a final 'natural flow' wing geometry was designed that provides an improvement in aerodynamic performance compared with that of a baseline conventional uncambered wing, linear-theory cambered wing, and near-conical wing

Development of a glucose sensor based on competitive binding and laser-excited fluorescence

An optical glucose sensor has been developed using competitive binding in conjunction with energy transfer. Sensor response is based on competition between glucose and dextran for a limited number of binding sites on the protein concanavalin A (conA). The system is optically monitored using fluorescent donor-acceptor dye pairs labeled to concanavalin A and dextran. When the dyes are sufficiently close, on the order of 50 A, energy is transferred from the donor emission band to the overlapping excitation band of the acceptor. This nonradiative, singlet-singlet transfer of energy enhances the acceptor emission at the expense of donor emission. In absence of glucose, the conA and dextran are bound together and energy transfer takes place. Upon addition of glucose, the dextran is displaced, and energy transfer is disrupted. The ratio of the two emission intensities can be related to glucose concentration. Donor-acceptor systems investigated included energy transfer from fluorescein (FITC) to three different types of rhodamine, TRITC, XRITC, and Texas Red, and both coumarin and fluorescamine donating energy to FITC. The system that gave the largest change in intensity involved FITC labeled conA as the donor and TRITC labeled dextran as the donor. Fluorescence was measured with both conventional fluorescence instrumentation and a computer controlled, laser excited spectrometer. The laser instrument was developed specifically for the optical glucose sensor, but was designed to support a wide range of fiber optic sensors. Instrument components include a nitrogen pumped dye laser, fiber optic beam splitters, photomultiplier tubes fitted with interference filters for wavelength selection, and boxcar averagers. Instrument development included calibration of the dye laser, evaluation of different fiber optic beam splitter arrangements, reduction of stray light, and evaluation of the boxcar averagers. The spectrometer was interfaced to an Apple IIc computer which was programmed to collect the data, perform baseline corrections, ratio the two channels, and trigger the laser to initiate the next data point. The instrument\u27s detection level, using Rhodamine 6G standards, is 1.0 $\times$ 10\sp{-9}molar and is limited by stray light. Precision of the instrument is approximately 3% and is limited by drift of the boxcar averagers

Fin Flutter Analysis

This report summarizes the experimental process executed to study fin flutter characteristics. The experiment analyzed the influence of the relationship between structural dynamics and aerodynamics on flutter characteristics. Theoretical models were created in PATRAN/NASTRAN and FinSim for comparison to experimental results and to set the envelope of the physical experiments. The theoretical analysis predicted the occurrence of flutter near Mach 1 or Mach 5. The physical model was constructed of solid aluminum with machined holes for the inertial sensors. Two test runs were completed to collect data on the displacement of the fin in the supersonic wind tunnel. Additionally, the tests sought to identify any evidence of flutter as determined by the theorized model. The results showed evidence of both bending and twisting in the fin

The Mass-Richness Relation of MaxBCG Clusters from Quasar Lensing Magnification using Variability

Accurate measurement of galaxy cluster masses is an essential component not only in studies of cluster physics, but also for probes of cosmology. However, different mass measurement techniques frequently yield discrepant results. The SDSS MaxBCG catalog's mass-richness relation has previously been constrained using weak lensing shear, Sunyaev-Zeldovich (SZ), and X-ray measurements. The mass normalization of the clusters as measured by weak lensing shear is >~25% higher than that measured using SZ and X-ray methods, a difference much larger than the stated measurement errors in the analyses. We constrain the mass-richness relation of the MaxBCG galaxy cluster catalog by measuring the gravitational lensing magnification of type I quasars in the background of the clusters. The magnification is determined using the quasars' variability and the correlation between quasars' variability amplitude and intrinsic luminosity. The mass-richness relation determined through magnification is in agreement with that measured using shear, confirming that the lensing strength of the clusters implies a high mass normalization, and that the discrepancy with other methods is not due to a shear-related systematic measurement error. We study the dependence of the measured mass normalization on the cluster halo orientation. As expected, line-of-sight clusters yield a higher normalization; however, this minority of haloes does not significantly bias the average mass-richness relation of the catalog.Comment: 9 pages. Accepted for publication in Ap