Editorial

No abstract available

A Test of the Particle Paradigm in N-Body Simulations

We present results of tests of the evolution of small ``fluid elements'' in cosmological N--body simulations, to examine the validity of their treatment as particles. We find that even very small elements typically collapse along one axis while expanding along another, often to twice or more their initial comoving diameter. This represents a possible problem for high--resolution uses of such simulations.Comment: Uses aasms4.sty; accepted for publication in ApJ Letters. Files available also at ftp://kusmos.phsx.ukans.edu/preprints/ates

Editorial

No abstract available

Sulfur isotopes of hydrothermal vent fossils and insights into microbial sulfur cycling within a lower Paleozoic (Ordovician‐early Silurian) vent community

This study was supported by a UK Natural Environment Research Council grant (NERC; number NE/R000670/1 to AG). MG is also grateful for support from an Ifremer Postdoctoral Fellowship. Alvinella samples were collected with the help of a NERC Small Grant (number NE/C000714/1 to CTSL). S isotopic analyses were undertaken under NERC Facility awards IP-1755-1117 and IMF672/1118.Symbioses between metazoans and microbes involved in sulfur cycling are integral to the ability of animals to thrive within deep‐sea hydrothermal vent environments; the development of such interactions is regarded as a key adaptation in enabling animals to successfully colonize vents. Microbes often colonize the surfaces of vent animals and, remarkably, these associations can also be observed intricately preserved by pyrite in the fossil record of vent environments, stretching back to the lower Paleozoic (Ordovician‐early Silurian). In non‐vent environments, sulfur isotopes are often employed to investigate the metabolic strategies of both modern and fossil organisms, as certain metabolic pathways of microbes, notably sulfate reduction, can produce large sulfur isotope fractionations. However, the sulfur isotopes of vent fossils, both ancient and recently mineralized, have seldom been explored, and it is not known if the pyrite‐preserved vent organisms might also preserve potential signatures of their metabolisms. Here, we use high‐resolution secondary ion mass spectrometry (SIMS) to investigate the sulfur isotopes of pyrites from recently mineralized and Ordovician‐early Silurian tubeworm fossils with associated microbial fossils. Our results demonstrate that pyrites containing microbial fossils consistently have significantly more negative δ34S values compared with nearby non‐fossiliferous pyrites, and thus represent the first indication that the presence of microbial sulfur‐cycling communities active at the time of pyrite formation influenced the sulfur isotope signatures of pyrite at hydrothermal vents. The observed depletions in δ34S are generally small in magnitude and are perhaps best explained by sulfur isotope fractionation through a combination of sulfur‐cycling processes carried out by vent microbes. These results highlight the potential for using sulfur isotopes to explore biological functional relationships within fossil vent communities, and to enhance understanding of how microbial and animal life has co‐evolved to colonize vents throughout geological time.Publisher PDFPeer reviewe

The effectiveness and cost-effectiveness of of community diagnostic centres: a rapid review

Objectives: To examine the effectiveness of community diagnostic centres as a potential solution to increasing capacity and reducing pressure on secondary care in the UK.Methods: A comprehensive search for relevant primary studies was conducted in a range of electronic sources in August 2022. Screening and critical appraisal were undertaken by two independent reviewers. There were no geographical restrictions or limits to year of publication. A narrative synthesis approach was used to analyse data and present findings.Results: Twenty primary studies evaluating twelve individual diagnostic centres were included. Most studies were specific to cancer diagnosis and evaluated diagnostic centres located within hospitals. The evidence of effectiveness appeared mixed. There is evidence to suggest diagnostic centres can reduce various waiting times and reduce pressure on secondary care. However, cost-effectiveness may depend on whether the diagnostic centre is running at full capacity. Most included studies used weak methodologies that may be inadequate to infer effectiveness.Conclusion: Further well-designed, quality research is needed to better understand the effectiveness and cost-effectiveness of community diagnostic centres

The Size and Shape of Voids in Three-Dimensional Galaxy Surveys

The sizes and shapes of voids in a galaxy survey depend not only on the physics of structure formation, but also on the sampling density of the survey and on the algorithm used to define voids. Using an N-body simulation with a CDM power spectrum, we study the properties of voids in samples with different number densities of galaxies, both in redshift space and in real space. When voids are defined as regions totally empty of galaxies, their characteristic volume is strongly dependent on sampling density; when they are defined as regions whose density is 0.2 times the mean galaxy density, the dependence is less strong. We compare two void-finding algorithms, one in which voids are nonoverlapping spheres, and one, based on the algorithm of Aikio and Mahonen, which does not predefine the shape of a void. Regardless of the algorithm chosen, the characteristic void size is larger in redshift space than in real space, and is larger for low sampling densities than for high sampling densities. We define an elongation statistic Q which measures the tendency of voids to be stretched or squashed along the line of sight. Using this statistic, we find that at sufficiently high sampling densities (comparable to the number densities of galaxies brighter than L_*), large voids tend to be slightly elongated along the line of sight in redshift space.Comment: LaTex, 21 pages (including 7 figures), ApJ, submitte

Evaluating oribi translocations for conservation : the importance of translocation guidelines

At a global scale, anthropogenically-mediated disturbances have resulted in the extirpation of species and declines in both population and range size. Furthermore, land transformation and habitat fragmentation have limited the ability of species to disperse naturally throughout their ranges. To compensate for both this defaunation and disruption of animal movement patterns, rewilding and restoration are becoming increasingly important approaches to conserve and promote biodiversity. Central to both of these concepts, as well as wildlife management and conservation in general, is the translocation of species.The National Research Foundation (90783), the Endangered Wildlife Trust, and a Gay Langmuir bursary from the University of KwaZulu-Natal.https://sawma.co.za/african-journal-of-wildlife-researcham2022Mammal Research InstituteZoology and Entomolog

Cross-validation of the Work Organization Assessment Questionnaire across genders: a study in the Australian health care sector

Objectives The main aim of this study was to examine the measurement invariance of the Work Organisation Assessment Questionnaire (WOAQ) across genders in a group of healthcare employees, using bifactor modelling. There is a very limited research that uses invariance testing of bifactor models, despite their usefulness. Establishing validity of the WOAQ in this way is important for demonstrating its relevance for both males and females. Methods A bifactor modelling procedure was used here to examine the validity of the WOAQ with a sample of 946 paramedics employed in a large Australian organization in the healthcare sector. Results The results of this study show that the WOAQ has good psychometric properties across genders in healthcare settings. In addition, there were significant mean differences between males and females in their perceptions of ‘quality of relationships with colleagues’, and ‘reward and recognition’. There were no differences between males and females on the remaining factors: ‘quality of relationships with the management’, ‘quality of relationships with colleagues’, and ‘quality of the physical environment’. Conclusions The use of bifactor modelling to establish the cross-validity of the WOAQ across male and female paramedics adds to evidence for the measure’s good psychometric properties. The findings add to those of previous research that has used higher order Confirmatory Factor Analysis (CFA). Moreover, mean differences between males and females were found to be significant in two of the five WOAQ subscales. These findings have practical implications for healthcare organizations, in terms of assessing work characteristics and developing activities to support the health and well-being of their employees

Microbial-tubeworm associations in a 440 million year old hydrothermal vent community

Microorganisms are the chief primary producers within present-day deep-sea hydrothermal vent ecosystems, and play a fundamental role in shaping the ecology of these environments. However, very little is known about the microbes that occurred within, and structured, ancient vent communities. The evolutionary history, diversity and the nature of interactions between ancient vent microorganisms and hydrothermal vent animals are largely undetermined. The oldest known hydrothermal vent community that includes metazoans is preserved within the Ordovician to early Silurian Yaman Kasy massive sulfide deposit, Ural Mountains, Russia. This deposit contains two types of tube fossil attributed to annelid worms. A re-examination of these fossils using a range of microscopy, chemical analysis and nano-tomography techniques reveals the preservation of filamentous microorganisms intimately associated with the tubes. The microfossils bear a strong resemblance to modern hydrothermal vent microbial filaments, including those preserved within the mineralized tubes of the extant vent polychaete genus Alvinella. The Yaman Kasy fossil filaments represent the oldest animal–microbial associations preserved within an ancient hydrothermal vent environment. They allude to a diverse microbial community, and also demonstrate that remarkable fine-scale microbial preservation can also be observed in ancient vent deposits, suggesting the possible existence of similar exceptionally preserved microfossils in even older vent environments