This book contains short biographies of Galileo, Newton, Herschel, Huggins, Hale, Eddington, Shapley and Hubble - eight astronomers who broke with traditions and defined the cosmos as we know it now.
This is the first comprehensive biography of one of the greatest and most careful observational astronomers of all time. He mapped the southern sky and named many of the constellations. In addition, ...he contributed to geodesy, navigation, and celestial mechanics.
This is a comprehensive biography of a great observational astronomer, Nicolas-Louis de La Caille (1713–62). Though educated for the priesthood, La Caille refused to be ordained and turned instead to ...astronomy. Early on he was made Professor of Mathematics at the Collège Mazarin, where he propagated Newtonian ideas. He also built an observatory from which he conducted his lifelong programme of improving the positions of the bright stars and determining the orbits of the Moon and planets. At the Cape of Good Hope (1751–53) he made the first systematic telescopic sky survey and mapped the southern heavens. He defined and named many of the constellations. Making measurements simultaneously with colleagues in Europe, he determined the distances of the Sun, the Moon and the planets Venus and Mars. The information he gathered was critical to the development of the theory of planetary perturbations. He measured the radius of the earth and came to the conclusion that it is pear-shaped. He also made extensive notes on the Cape environment as well as on the colonists and slaves. In some ways rather fierce, La Caille had a serious demeanour and abhorred frivolity and dishonesty. Nevertheless, he had a small number of close friends with whom he could relax and unbend. His colleagues and former pupils loved and respected him in spite of his forbidding manner.
We report 580 sets of JHKL observations of 63 long-period Mira-like variables in the Sgr I clear field located in the Bulge of our Galaxy at 3° from the Centre. These include 8 IRAS sources whose ...periods are given for the first time. No variable shows a period in excess of 700 d. The sample appears to be close to complete and it is demonstrated that the apparent period distribution from a given survey is highly dependent on the wavelength used. The colours and other properties of the Sgr I Miras are compared with those in the LMC and the solar neighbourhood. Although the J-K colours of the shorter-period Sgr I Miras are similar to those of their counterparts in the LMC, showing that they have similar temperatures at a given period, differences exist in their J-H and H-K colours. At longer periods, the Sgr I Miras appear redder in all colour indices than the LMC relations and their extrapolations. The apparent K-log P and mbol-log P relations for Miras in the Sgr I field are derived. The scatter about these relations is higher in Sgr I than for the LMC because of the significant depth of the Bulge in the line of sight. In conjunction with a simple model of the Bulge, the K-log P and Mbol-log P relations for LMC Miras are used to discuss the distance of the Sgr I field, the best value of which is found to be 8.7 ± 0.7 kpc (taking the distance modulus of the LMC to be 18.55 with s.e. 0.1 - 0.15). The value of R0, the distance to the Galactic Centre, is 0.2 kpc greater if the Sgr I field is part of a bar lying in the Galactic Plane and inclined at 45° to the line of sight.
The apparent size of stars is a crucial benchmark for fundamental stellar properties such as effective temperatures, radii and surface gravities. While interferometric measurements of stellar angular ...diameters are the most direct method to gauge these, they are still limited to relatively nearby and bright stars, which are saturated in most of the modern photometric surveys. This dichotomy prevents us from safely extending well-calibrated relations to the faint stars targeted in large spectroscopic and photometric surveys. Here, we alleviate this obstacle by presenting South African Astronomical Observatory near-infrared JHK observations of 55 stars: 16 of them have interferometric angular diameters and the rest are in common with the 2 Micron All Sky Survey (2MASS, unsaturated) data set, allowing us to tie the effective temperatures and angular diameters derived via the infrared flux method to the interferometric scale. We extend the test to recent interferometric measurements of unsaturated 2MASS stars, including giants, and the metal-poor benchmark target HD122563. With a critical evaluation of the systematics involved, we conclude that a 1 per cent accuracy in fundamental stellar parameters is usually within reach. Caution, however, must be used when indirectly testing a T
eff scale via colour relations as well as when assessing the reliability of interferometric measurements, especially at submilliarcsec level. As a result, rather different effective temperature scales can be compatible with a given subset of interferometric data. We highlight some caveats to be aware of in such a quest and suggest a simple method to check against systematics in fundamental measurements. A new diagnostic combination seismic radii with astrometric distances is also presented.
Long-term (up to 10 000 d) monitoring has been undertaken for 41 Seyferts in the near-infrared (1.25–3.45 μm). All but two showed variability, with amplitudes at K in the range <0.1 to >1.1 mag. The ...time-scale for detectable change is from about one week to a few years. Where contemporary observations of variability in X-rays, ultraviolet (UV) or visible light exist, it is found that the near-infrared varies in a similar way, though in some cases the shorter-wavelength infrared (IR) bands are diluted by underlying galaxy radiation. A simple cross-correlation study indicates that there is evidence for delays of up to several hundred d between the variations seen at the shortest wavelengths (U or J) and the longest (L) in many galaxies. In particular, the data for Fairall 9 now extend to twice the interval covered in earlier publications and the delay between its UV and IR outputs is seen to persist. An analysis of the fluxes shows that, for any given galaxy, the colours of the variable component of its nucleus are usually independent of the level of activity. The state of activity of the galaxy can be parameterized. Taken over the whole sample, the colours of the variable components fall within moderately narrow ranges. In particular, the H−K colour is appropriate to a blackbody of temperature 1600 K. The H−K excess for a heavily reddened nucleus can be determined and used to find EB−V, which can be compared to the values found from the visible region broad line ratios. Using flux–flux diagrams, the flux within the aperture from the underlying galaxies can often be determined without the need for model surface brightness profiles. In many galaxies it is apparent that there must be an additional constant contribution from warm dust.
Summary
Background
Antepartum anti‐viral therapy (AVT) is often administered to prevent perinatal transmission of hepatitis B virus (HBV) infection. Little is known about the effect of AVT on ...post‐partum flare rates and severity.
Aim
To examine whether extending AVT beyond birth influences the post‐partum course.
Methods
One hundred and one pregnancies in 91 women with HBV DNA levels ≥log 7 IU/mL were included. AVT (initially lamivudine, later tenofovir disoproxil fumarate) was commenced from 32 weeks gestation and stopped soon after birth and at 12 weeks post‐partum. Outcomes according to post‐partum treatment duration were examined: Group 1 = AVT ≤4 weeks (n = 44), Group 2 = AVT >4 weeks (n = 43), Group 3 = no AVT (n = 14).
Results
The majority of women were HBeAg+ (97%), median age 29 years, baseline HBV DNA log 8.0 IU/mL and follow‐up 48 weeks post‐partum. Post‐partum treatment duration was 2 weeks for Group 1 and 12 weeks for Group 2, P < 0.01. Flare rates were not significantly different: Group 1 = 22/44 (50%), Group 2 = 17/43 (40%) and Group 3 = 4/14 (29%), P = 0.32. Onset of flare was similar at 8/10/9 weeks post‐partum for Groups 1/2/3 respectively, P = 0.34. The majority of flares spontaneously resolved. HBeAg seroconversion (n = 1/5/1 in Groups 1/2/3, P = 0.27) was not associated with treatment duration or the occurrence of a post‐partum flare.
Conclusions
Post‐partum flares are common and usually arise early after delivery. They are often mild in severity and most spontaneously resolve. Extending anti‐viral therapy does not protect against post‐partum flares or affect HBeAg seroconversion rates.
Period–luminosity sequences have been shown to exist among the semiregular variables (SRVs) in the Magellanic Clouds, the bulge of the Milky Way galaxy and elsewhere. Using modern-period and revised ...Hipparcos parallax data, this paper demonstrates that they also appear among the M giant SRVs of the solar neighbourhood. Their distribution in the K, log P diagram resembles that of Bulge stars more closely than those in the Magellanic Clouds. The prevalence of mass-loss among local M-type SRVs and its dependence on period and spectral subtype are also discussed. K−12, a measure of circumstellar dust emission, increases clearly with V amplitude, M giant subtype and log P.
Objective
The aims of the study were: (1) to clarify the definitions of “migrant” used in occupational health research; (2) to summarize migrant workers’ industry sectors, occupations and employment ...conditions; (3) to identify the occupational health and safety services available to migrant workers; (4) to summarize work-related health problems found among migrant workers; (5) to identify the methodological challenges to research into occupational health of migrant workers; and (6) to recommend improvements in migrant occupational health research.
Methods
This position paper was prepared by researchers from several European countries and Australia, working within the EU COST Action OMEGA-NET. The paper drew on two recent systematic reviews on the occupational health of international migrant workers and other literature, and also identified uncertainties and gaps in the research literature. Migrants may, for example, be temporary or permanent, moving for specific jobs migrants or other reasons. Their ethnicity and language capabilities will affect their work opportunities.
Results
The occupational health literature seldom adequately identifies the heterogeneity or characteristics of the migrant group being studied. Migrants tend to work in more physically and mentally demanding environments with higher exposures than native workers. Migrants tend to have an increased risk of physical and mental ill health, but less access to health care services. This has been demonstrated recently by high rates of COVID-19 and less access to health care. There have been a number of cross-sectional studies of migrant health but few long-term cohort studies were identified. Other study designs, such as registry-based studies, surveys and qualitative studies may complement cross-sectional studies. Mixed-methodology studies would be valuable in research on migrants’ occupational health. Language and lack of trust are barriers to migrant research participation.
Conclusion
Targeted research, especially longitudinal, identifying how these economically important but often-vulnerable workers can be best assisted is needed. Researchers should identify the characteristics of the migrant workers that they are studying including visa/migration circumstances (temporary, permanent, undocumented), racial and ethnic characteristics, existing skills and language abilities.
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