The legacy of nineteenth-century replicas for object cultural biographies : lessons in duplication from 1830s Fife

Peer reviewedPostprin

Oxygen Abundances in Two Metal-Poor Subgiants from the Analysis of the 6300 A Forbidden O I Line

Recent LTE analyses (Israelian et al. 1998 and Bosegaard et al. 1999) of the OH bands in the optical-ultraviolet spectra of nearby metal-poor subdwarfs indicate that oxygen abundances are generally higher than those previously determined. The difference increases with decreasing metallicity and reaches delta([O/Fe]) ~ +0.6 dex as [Fe/H] approaches -3.0. Employing high resolution (R = 50000), high S/N (~ 250) echelle spectra of the two stars found by Israelian et al. (1998) to have the highest [O/Fe]-ratios, viz, BD +23 3130 and BD +37 1458, we conducted abundance analyses based on about 60 Fe I and 7-9 Fe II lines. We determined from Kurucz LTE models the values of the stellar parameters, as well as abundances of Na, Ni, and the traditional alpha-elements, independent of the calibration of color vs $T_{eff}$ scales. We determined oxygen abundances from spectral synthesis of the stronger line (6300 A) of the [O I] doublet. The syntheses of the [O I] line lead to smaller values of [O/Fe], consistent with those found earlier among halo field and globular cluster giants. We obtain [O/Fe] = +0.35 +/- 0.2 for BD +23 3130 and +0.50 +/- 0.2 for BD +37 1458. In the former, the [O I] line is very weak (~ 1 mA), so that the quoted [O/Fe] value may in reality be an upper limit. Therefore in these two stars a discrepancy exists between the [O/Fe]- ratios derived from [O I] and the OH feature, and the origin of this difference remains unclear. Until the matter is clarified, we suggest it is premature to conclude that the ab initio oxygen abundances of old, metal-poor stars need to be revised drastically upward.Comment: 38 pages, 5 tables, 14 figures To appear in July 1999 AJ Updated April 16, 1999. Fixed typo

Differences in Tsimane Children’s Growth Outcomes and Associated Determinants as Estimated by WHO Standards vs. Within-Population References

Anthropometric measures are commonly converted to age stratified z-scores to examine variation in growth outcomes in mixed-age and sex samples. For many study populations, z-scores will differ if calculated from World Health Organization (WHO) growth standards or within-population references. The specific growth reference used may influence statistical estimates of growth outcomes and their determinants, with implications for biological inference. We examined factors associated with growth outcomes in a sample of 152 Tsimane children aged 0–36 months. The Tsimane are a subsistence-scale population in the Bolivian Amazon with high rates of infectious disease and growth faltering. To examine the influence of growth reference on statistical inferences, we constructed multiple plausible models from available infant, maternal, and household attributes. We then ran identical models for height-for-age (HAZ), weight-for-age (WAZ), and weight-for-height (WHZ), with z-scores alternately calculated from WHO and robust Tsimane Lambda-Mu-Sigma growth curves. The distribution of WHO relative to Tsimane HAZ scores was negatively skewed, reflecting age-related increases in lower HAZ. Standardized coefficients and significance levels generally agreed across WHO and Tsimane models, although the strength and significance of specific terms varied in some models. Age was strongly, negatively associated with HAZ and WAZ in nearly all WHO, but not Tsimane models, resulting in consistently higher R2 estimates. Age and weaning effects were confounded in WHO models. Biased estimates of determinants associated with WHO HAZ may be more extreme in small samples and for variables that are strongly age-patterned. Additional methodological considerations may be warranted when applying WHO standards to within-population studies, particularly for populations with growth patterns known to systematically deviate from those of the WHO reference sample

Validation of a finite element model of the cold roll forming process on the basis of 3D geometric accuracy

Cold roll forming is an incremental sheet metal forming process used to supply products to numerous industries such as automotive, architecture and construction, etc. In recent years there has been an increase in the demand by customers for high value products, through the forming of high strength materials, or complex profiles. Such demands increase the challenges faced by the tooling designer to bring a successful product through from design to manufacture, on time and within specification. Finite element (FE) simulations are increasingly applied in industry due to the desired advantage of reducing design iterations by allowing the designer to investigate the effects of parameter changes, without the risk of expensive tooling costs. Some successful validation of the numerical modelling of the cold roll forming process can be found in literature, in particular when analysing the strain distribution across the material or comparing the final rolled profile geometry. However, cold roll forming is a continuous process and no one has published work on the measurement of the profile on a pass to pass basis, in particular, the three dimensional geometry of the profile. Experimental trials were carried out to obtain a 3D point cloud model of the top surface of a roll formed section. This investigation aimed to quantify how accurate FE simulation may be in relation to physical data

Ionization balance of Ti in the photospheres of the Sun and four late-type stars

In this paper we investigate statistical equilibrium of Ti in the atmospheres of late-type stars. The Ti I/Ti II level populations are computed with available experimental atomic data, except for photoionization and collision induced transition rates, for which we have to rely on theoretical approximations. For the Sun, the NLTE line formation with adjusted H I inelastic collision rates and MAFAGS-OS model atmosphere solve the long-standing discrepancy between Ti I and Ti II lines. The NLTE abundances determined from both ionization stages agree within $0.01$ dex with each other and with the Ti abundance in C I meteorites. The Ti NLTE model does not perform similarly well for the metal-poor stars, overestimating NLTE effects in the atmospheres of dwarfs, but underestimating overionization for giants. Investigating different sources of errors, we find that only [Ti/Fe] ratios based on Ti II and Fe II lines can be safely used in studies of Galactic chemical evolution. To avoid spurious abundance trends with metallicity and dwarf/giant discrepancies, it is strongly recommended to disregard Ti I lines in abundance analyses, as well as in determination of surface gravities.Comment: 16 pages, accepted for publication in MNRA

Avian Survey Methods for Use at Airports

Adverse effects and damage caused by interactions between humans and wildlife are increasing (DeStephana and DeGraaf 2003). To manage wildlife effectively- whether to mitigate damage. to enhance safety, or to reach conservation goals-wildlife biologists must identify hazards posed by or to members of a particular species (i.e., a population) or guild, and then prioritize management goals and specific actions. We examine the special problem of managing birds to reduce hazards to aviation, particularly those species known to cause structural damage to aircraft when struck and that ·pose problems to airport facilities (Dolbeer et al. 2000, Cleary and Dolbeer 2005, DeVault et al. 2011). Effective management of hazardous species at airports requires knowledge of species abundance and how abundance varies over time. In this context, the quality of the sampling methodology used will influence a biologist\u27s ability to accurately quantify avian hazards and to understand the ecological interactions of populations or guilds using airport environments

Avian Survey Methods for Use on Airports

Management of wildlife, whether to mitigate damage, enhance safety, or effect conservation goals, requires identification of hazards posed by or to members of a particular species population or guild, and prioritization of management goals. We examined the special problem of managing birds to reduce hazards to aviation, particularly those species known to cause structural damage to aircraft when struck, as well as posing problems to airport facilities. Our objectives were to synthesize sampling theory and methods to provide airport biologists with 1) means to design and implement an avian survey on an airport that will maximize accuracy in quantifying avian hazards; 2) an understanding of bias and precision, and their influences on quantification of avian hazards; 3) suggestions on how to quantify avian hazards and use these data to estimate relative risk posed to aviation safety by a particular species or guild by time period and habitat type; and 4) knowledge of how data can be used to prioritize management goals. Our recommendations are intended to compliment U.S. Federal Aviation Administration procedures for Wildlife Hazard Assessments and subsequent management on airports. We stress the need for survey data to be ecologically relevant and accurate, such that management guidelines are defensible. However, we recognize that “real world” issues, such as regulatory, labor, and financial constraints, as well as the dynamics of airport environments, inevitably influence survey methods. Though we do not advocate use of naive count data in estimating relative abundance or habitat use, we recognize that animal observations obtained by airport biologists outside of a standardized sampling protocol are critical for identifying potential hazards to aviation safety. We recommend field testing of our suggestions and development of training materials for airport biologists that distill the information that we will present in light of constraints affecting survey design and conduct

Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars

Branching fraction measurements from Fourier transform spectra in conjunction with published radiative lifetimes are used to determine transition probabilities for 263 lines of neutral chromium. These laboratory values are employed to derive a new photospheric abundance for the Sun: log $\epsilon$(Cr I)$_{\odot}$ = 5.64$\pm$0.01 ($\sigma = 0.07$). These Cr I solar abundances do not exhibit any trends with line strength nor with excitation energy and there were no obvious indications of departures from LTE. In addition, oscillator strengths for singly-ionized chromium recently reported by the FERRUM Project are used to determine: log $\epsilon$(Cr II)$_{\odot}$ = 5.77$\pm$0.03 ($\sigma = 0.13$). Transition probability data are also applied to the spectra of three stars: HD 75732 (metal-rich dwarf), HD 140283 (metal-poor subgiant), and CS 22892-052 (metal-poor giant). In all of the selected stars, Cr I is found to be underabundant with respect to Cr II. The possible causes for this abundance discrepancy and apparent ionization imbalance are discussed.Comment: 44 pages, 6 figure

Chemical stratification in the atmosphere of Ap star HD 133792. Regularized solution of the vertical inversion problem

High spectral resolution studies of cool Ap stars reveal conspicuous anomalies of the shape and strength of many absorption lines. This is a signature of large atmospheric chemical gradients produced by the selective radiative levitation and gravitational settling of chemical species. Here we present a new approach to mapping the vertical chemical structures in stellar atmospheres. We have developed a regularized chemical inversion procedure that uses all information available in high-resolution stellar spectra. The new technique for the first time allowed us to recover chemical profiles without making a priori assumptions about the shape of chemical distributions. We have derived average abundances and applied the vertical inversion procedure to the high-resolution VLT UVES spectra of the weakly magnetic, cool Ap star HD 133792. Our analysis yielded improved estimates of the atmospheric parameters of HD 133792. We show that this star has negligible vsini and the mean magnetic field modulus =1.1+/-0.1 kG. We have derived average abundances for 43 ions and obtained vertical distributions of Ca, Si, Mg, Fe, Cr, and Sr. All these elements except Mg show high overabundance in the deep layers and solar or sub-solar composition in the upper atmosphere of HD 133792. In contrast, the Mg abundance increases with height. We find that transition from the metal-enhanced to metal-depleted zones typically occurs in a rather narrow range of depths in the atmosphere of HD 133792. Based on the derived photospheric abundances, we conclude that HD 133792 belongs to the rare group of evolved cool Ap stars, which possesses very large Fe-peak enhancement, but lacks a prominent overabundance of the rare-earth elements.Comment: Accepted by A&A; 12 pages, 9 figure