Women at work in NASA

Photographs and brief descriptions summarize the diversity of the female work force at NASA. Jobs are classified as: (1) technical support positions; (2) clerical and nonprofessional administrative; (3) professional administrative; and (4) professional scientific and engineering

Bosonic Operator Methods for the Quark Model

Quark model matrix elements can be computed using bosonic operators and the holomorphic representation for the harmonic oscillator. The technique is illustrated for normal and exotic baryons for an arbitrary number of colors. The computations are much simpler than those using conventional quark model wavefunctions

Simultaneous measurement of circular dichroism and Faraday rotation at terahertz frequencies using heterodyne detection

A far-infrared system measures the full complex Faraday angle, rotation as well as ellipticity, with an unprecedented accuracy of 10\,$\mu$rad/T. The system operates on several far-infrared laser lines in the spectral range from 0.3 to 6 THz and produces results as a continuous function of temperature from 10 to 310K and applied fields between $\pm$ 8\,T. Materials successfully measured include GaAs 2-DEG heterostructures, various high temperature superconductors including Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$, Pr$_{2 - x}$Ce$_{x}$CuO$_4$, and La$_{2-x}$Sr$_x$CuO$_4$, and single crystals of the topological insulator Bi$_2$Se$_3$.Comment: Submitted to Review of Scientific Instruments (RSI

Lidar measurements of thermal structure

Rayleigh backscatter observations at 532 nm and 355 nm of relative atmospheric density above Aberystwyth on a total of 93 nights between Dec. 1982 and Feb. 1985 were used to derive the height variation of temperature in the upper stratosphere and mesosphere. Preliminary results for height up to about 25 km were also obtained from observations of Raman backscattering from nitrogen molecules. Comparisons were carried out for stratospheric heights with satellite borne measurements; good agreement was found between equivalent black body temperatures derived from the lidar observations and those obtained from nadir measurements in three channels of the stratosphere sounder units on NOAA satellites; the lidar based atmospheric temperatures have shown general agreement with but a greater degree of structure than the limb sounding measurements obtained using the SAMS experiment on the NOAA-7 satellite. In summer, stratospheric and mesospheric temperatures showed a smooth height variation similar to that of the CIRA model atmosphere. In contrast, the winter data showed a great variability with height, and marked temperature changes both from night to night and within a given night

Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The $\Omega^-$ magnetic moment is found to be in good agreement with experiment: $\mu_{\Omega^-}$ is predicted to be $-1.97 \mu_N$ compared to the experimental result of ($-$2.02 $\pm$ 0.05) $\mu_N$.Comment: 19 pages, 2 figure

The Dynamics of Child Poverty: Britain and Germany Compared

We compare patterns of movements into and out of poverty by children in Britain and Germany using data from the British Household Panel Survey and the German Socio- Economic Panel for the period 1992-7. Compared to Germany, in Britain poverty persistence is greater, and poverty exit rates in particular are lower. In both countries poverty is particularly persistent among children in lone parent households and households with a nonworking head. Events such as family formation and dissolution, and changes in household labour market attachment are associated with child poverty transitions in the direction expected, and in both countries. However a large fraction of the observed poverty transitions are not accounted for by these events.

The reported use and effectiveness of Hypericum (St John’s wort) on affective symptoms in a depression self-help group

A recent meta-analysis suggested that Hypericum perforatum (St John’s wort) is an effective treatment for mild to moderate depression and may have a superior side-effect profile to some antidepressant drugs. The aim of this study was to assess the use of herbal remedies in treating depressive and anxiety symptoms, as reported by members of the UK self-help organization Depression Alliance using self-completed questionnaires. More than 50% of the 452 respondents reported using Hypericum, onequarter of whom also reported concurrent use of traditional antidepressants. Most of the sample reported sufficient symptoms for warranting a diagnosis of major depression, with the majority also describing symptoms suggestive of co-morbid psychiatric conditions. One-half of the Hypericum users experienced symptom improvement, which for most occurred within the first 4 weeks of use. Response was better for those with mild as compared to severe symptoms and poorer for those taking Hypericum alongside other antidepressants. The responders were generally older than non-responders. Adverse effects were reported by one-quarter of users and were mostly psychological in nature. This retrospective survey indicated that use of herbal remedies was common in this population. Although often helpful in relieving symptoms, particularly in those with mild depression, there is a risk of adverse events and drug interaction

Critical Analysis of Baryon Masses and Sigma-Terms in Heavy Baryon Chiral Perturbation Theory

We present an analysis of the octet baryon masses and the $\pi N$ and $KN$ $\sigma$--terms in the framework of heavy baryon chiral perturbation theory. At next-to-leading order, ${\cal O}(q^3)$, knowledge of the baryon masses and $\sigma_{\pi N}(0)$ allows to determine the three corresponding finite low--energy constants and to predict the the two $KN$ $\sigma$--terms $\sigma^{(1,2)}_{KN} (0)$. We also include the spin-3/2 decuplet in the effective theory. The presence of the non--vanishing energy scale due to the octet--decuplet splitting shifts the average octet baryon mass by an infinite amount and leads to infinite renormalizations of the low--energy constants. The first observable effect of the decuplet intermediate states to the baryon masses starts out at order $q^4$. We argue that it is not sufficient to retain only these but no other higher order terms to achieve a consistent description of the three--flavor scalar sector of baryon CHPT. In addition, we critically discuss an SU(2) result which allows to explain the large shift of $\sigma_{\pi N}(2M_\pi^2) - \sigma_{\pi N}(0)$ via intermediate $\Delta (1232)$ states.Comment: 18 pp, TeX, BUTP-93/05 and CRN-93-0

Understanding physical changes and strength loss of E-glass fibres following exposure to elevated temperatures

The strength loss of glass fibres (GF) following exposure to elevated temperatures is a long-established phenomenon, yet the mechanism or mechanisms responsible for the strength decrease are not fully understood, aside from acknowledgement that surface flaws must become more severe by some means. As disposal of GF based composite materials by landfill has become untenable in many regions, interest in composite recyclability has increased. Separation of GFs from thermosetting polymers generally requires the use of high temperatures, which produces very weak fibres with minimal commercial value. In this context an understanding of the strength loss mechanisms is of importance in terms of efforts to mitigate fibre damage or to recover the strength of previously heated fibres. In addition to fibre strength loss, numerous other physical and chemical changes to heat treated (HT) or recycled GF have been described in the literature