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This paper investigates the potential of a lever-type pitch trimmer to cause an overstress in light and microlight aeroplanes. It concludes that this potential exists and could potentially cause a catastrophic structural failure – with the evidence from one reported fatal accident suggesting that this may have already happened. However, it is shown that this need not be the case, with restricted nose-up control authority, high manoeuvre stability and the use of a trim wheel (as opposed to a lever) with a restrictive rate of control input shown as three methods, most likely in combination, by which this potential can be removed. Suggestions are made for airworthiness standard wording which might be used to ensure adequate safety of future aircraft designs.
RR Lyrae stars both in the field and in clusters can be used to derive the metal abundance of the regions and systems where they are found.
(1) New data have been collected on a sample of field ab-type RR Lyraes with the aim of studying the composition of the halo and the disk of the galaxy, (Clementini et al. 1992a, in preparation), using the relation found by Clementini et al. (1991), (hereafter CTM91), between [Fe/H] and the equivalent width of the Ca II K-line W‘(K). (2) A quantitative chemical abundance analysis of the ab type RR Lyrae (V29) in the globular cluster M4 has been performed using high resolution, high S/N spectroscopy. We obtain [Fe/H]=–1.3 ± 0.2 and the α– elements (Mg and Ti) are overabundant by 0.6 dex. These results are in good agreement with determinations from high resolution spectra of giants and blue horizontal branch stars (Clementini et al. 1992b, in preparation).
This article addresses the origins of the immigration restriction movement in the late 19th century United States, a movement that realized its aims in the early 20th. It critiques the dominant scholarly interpretation, which holds that the movement sprang from a racism that viewed the new immigrants of this period as biologically inferior. It argues first that activists did not have at hand a biological theory sufficient to this characterization and did not employ one. It argues second that the movement arose as an adroit political response to labor market competition. The Republican Party recognized the discontent of resident workers (including those of older immigrant origin) with competition from new immigrants. The Party discerned ethnic differences among new and old immigrants and capitalized on these conditions in order to win elections. Ethnocentrism and middle-class anxiety over mass immigrant added to a movement that depended on bringing working class voters into the Party.
A remotely sensed method of assessing radiative-transfer processes which considers distinctive zones in the mountain-glacier drainage basin, increases the potential for comprehensive radiative-exchange analysis. By investigating terrain-reflected and terrain-emitted radiation using Landsat-5 Thematic Mapper images and digital elevation data, the objective of this study is to demonstrate the importance of local exchange in the computation of net shortwave and longwave radiation. The results show that terrain-reflected radiation estimates are required to calculate the total shortwave spectral irradiance in all parts of the basin This is necessary to compute accurate surface-cover reflectance and albedo values from the satellite imagery. Furthermore, the assessment of the terrain-emitted radiation explains why, especially on a clear day, the snow and ice covers in many parts of the basin have a very small longwave radiation deficit.
We think that it is possible to find the correct scale of abundance for metal-rich globular clusters thanks to the new generation of spectrographs, equipped with CCD cameras. We analyzed giants in ten globular clusters and Arcturus using high dispersion spectra acquired through the CASPEC spectrograph at the 3.6 m telescope at La Silla. The detector was an RCA CCD. Stars cooler than 4150 K were avoided since their absorption spectrum is too strong. By a comparison with standard Arcturus spectra, we found a small trend to overestimate equivalent widths. This systematic error affects the derived abundances only marginally. However, too large equivalent widths must produce too large metal abundances. Abundances were derived following a standard procedure.
The following report, which has been drawn up partly on the basis of the reports of the members of the Commission, touches briefly and without any attempt at completeness a few points of the recent developments in certain important fields falling within the domain of the Commission.
We present new results on a sample of RR Lyrae variables in the bar of the Large Magellanic Cloud (LMC), and report on the first detection of RR Lyrae in the dwarf spheroidal galaxy Leo I. Emphasis is given to the discussion of the distances to these galaxies as derived from their RR Lyrae populations, and of the impact on the “short” and “long” distance scale dichotomy.
High dispersion spectra of the high velocity star HD 39853 show that it is a slightly metal-poor ([Fe/H]=−0.5±0.1) giant of the old disk population, with exceptionally strong lithium lines. The abundance of Li, derived by synthetic spectra of the 6103.6 and 8126.4 Å lines, is log N(Li)=2.8±0.2. Abundances for the other observed elements are typical for mildly metal-poor giants: oxygen is slightly overabundant ([O/Fe]=+0.25±0.15); the C/N ratio is large (10±2); the 12C/13C ratio is small (6.6±1.2); and light elements (Na, Mg, Al, Si, Ca and Ti) are enhanced with respect to Fe by about a factor of 2.5. Observed s-elements (Zr and La) are not overabundant. Finally, no variation in the radial velocity of the star were detected at a level of 1 Km s-1.
The discrepancy between the long distance scale as derived, e.g., from Hipparcos-based distances to globular clusters via main sequence fitting to local subdwarfs, and the short distance scale as derived, e.g., from the absolute magnitude of field RR Lyrae stars via statistical parallaxes and the Baade–Wesselink method, could be accounted for if an intrinsic difference in luminosity of about 0.1−0.2 mag were found to exist between horizontal branch (HB) stars populating the sparse general field and the dense globular clusters.
We present an overview of our study of the short period variable stars in the Large Magellanic Cloud, and in the dwarf galaxies Fornax, Leo I, and NGC 6822. Light curves are presented for RR Lyrae stars, Anomalous Cepheids and, for the first time, for Dwarf Cepheids in the field and in the globular cluster #3 of the Fornax galaxy.
The Large Magellanic Cloud (LMC) is widely considered a corner-stone of the astronomical distance scale. However, a difference of 0.2−0.3 mag exists in its distance as predicted by the short and long distance scales. Distances to the LMC from Population II objects are founded on the RR Lyrae variables. We have undertaken an observational campaign devoted to the definition of the average apparent luminosity, and to the study of the mass–metallicity relation for RR Lyrae stars in the bar of the LMC. These are compared with analogous quantities for cluster RR Lyrae stars. The purpose is to see whether an intrinsic difference in luminosity, possibly due to a difference in mass, might exist between field and cluster RR Lyrae stars, which could be responsible for the well-known dichotomy between short and long distance scales. Preliminary results are presented on the V and B − V light curves, the average apparent visual magnitude, and the pulsational properties of 102 RR Lyrae stars in the bar of the LMC, observed at ESO in January 1999. The photometric data are accurately tied to the Johnson photometric system. Comparison is presented with the photometry of RR Lyrae stars in the bar of the LMC obtained by the MACHO collaboration (Alcock et al. 1996). Our sample includes 9 double-mode RR Lyrae stars selected from Alcock et al. (1997) for which an estimate of the metal abundance from the ΔS method is presented.
Despite the great progress which is being continuously made towards direct photoelectric recording, it is almost certain that for many years to come photographic plates will remain the most common means for detecting images of stars and stellar spectra, whether directly or through the intermediary of an image intensifier.
The photographic image of the spectrum of a star contains an enormous wealth of information whose utilization is one of the most important tasks of observational astrophysics. To achieve this task many difficult problems must be solved, the first being to express the information in a form which lends itself to further processing.
This is usually done by means of two different kinds of instruments.
In this contribution we give summaries of the oral and poster papers presented in Joint Discussion Session 4, Astrophysical Impact of Abundances in Globular Cluster Stars, at the XXVth IAU General Assembly. The full text of the papers can be found in Volume 75, issue 2, of the MEMORIE della Società Astronomica Italiana (Journal of the Italian Astronomical Society; see the web address: <sait.oat.ts.astro.it>).
The labor force behavior of older men has attracted the attention of economists, sociologists, and historians because it speaks to several concerns: the current crisis in Social Security, the origins and development of the welfare state, and the place of the aged in American history. The central issue is the decline in labor force participation among older men, a striking phenomenon of the twentieth century. In the nineteenth century, men past the age of 60 or 65 were quite likely to remain in the labor force. According to most historical accounts, their labor force participation declined monotonically from near 75% in 1890 to about 25% at present, a trend set in motion by cultural and economic changes which made the aged less valued by employers.
In his 1911 film What Shall We Do with Our Old? D.W. Griffith dramatized the belief that urban, industrial America had no place for the elderly. Fired for being too slow at his work, an impoverished old man cannot buy food or medicine for his wife, who languishes in their drab, one-room apartment. Justice Benjamin Cardozo told a similar tale in upholding the constitutionality of the Social Security Act (Helvering v. Davis, 301 U.S. 619 ): “The number of [aged] unable to take care of themselves is growing at a threatening pace. More and more our population is becoming urban and industrial instead of rural and agricultural.” Cardozo relied on studies by the U.S. Social Security Board (1937: 3), which found that “the major part of the industrial population . . . earns scarcely enough to provide for its existence. Savings are small and generally cover little more than the cost of burial insurance.” As a result, “industrial workers in [urban] areas . . . reach old age with few resources” (ibid.: 33).