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The layered sediments at Sinus Meridiani, Mars, ~ 1 km thick and covering 300,000 km2, have been probed by the rover Opportunity. Numerous observations on these rocks are reevaluated through the poorly-known model of the fluvial megafan. We conclude that at least some sections of the Meridiani stack are vestiges of large fluvial megafans. Our reasons include the following: the southern uplands of Mars are a feasible sediment source; sediment was likely delivered via rivers that cut the extensive valley network that drain the upland toward Meridiani; the units cover large areas commensurate with terrestrial megafan landscapes, and display the same very low slopes; megafan landscapes lie directly adjacent to upland sediment sources, as seen at Meridiani; megafans require neither closed basins nor waterbodies for sedimentation to occur; numerous examples of fluvial channels appear in some units; and morphologies of the widespread raised ridges of the ridge-forming unit (RFU) are suggestive of indurated channel networks seen on megafans in Oman. Features of vast aggradational landscapes as encapsulated in the novel megafan analogue thus provide answers to several key observations, whereas existing fluvial analyses usually apply the classic attributes of erosional landscapes, leading to significant difficulties in interpretation of the Meridiani units.
This study aims to understand the time-to-treatment initiation pre and post DAA access to inform strategies to improve HCV care. The data for our study were derived from the SuperMIX cohort study of people who inject drugs in Melbourne, Australia. Time-to-event analysis using Weibull accelerated failure time was performed for data collected between 2009 and 2021, among a cohort of HCV-positive participants. Among 223 participants who tested positive for active hepatitis C infection, 102 people (45.7%) reported treatment initiation, with a median time-to-treatment of 7 years. However, the median time-to-treatment reduced to 2.3 years for those tested positive after 2016. The study found that treatment with Opioid Agonist Therapy (TR 0.7, 95% CI 0.6–0.9), engagement with health or social services (TR 0.7, 95% CI 0.6–0.9), and having a first positive HCV RNA test after March 2016 (TR 0.3, 95% CI 0.2–0.3) were associated with a reduced time-to-treatment initiation. The study highlights the need for strategies to improve engagement with health services, including drug treatment services into routine HCV care to achieve timely treatment.
South Africa has embarked on major health policy reform to deliver universal health coverage through the establishment of National Health Insurance (NHI). The aim is to improve access, remove financial barriers to care, and enhance care quality. Health technology assessment (HTA) is explicitly identified in the proposed NHI legislation and will have a prominent role in informing decisions about adoption and access to health interventions and technologies. The specific arrangements and approach to HTA in support of this legislation are yet to be determined. Although there is currently no formal national HTA institution in South Africa, there are several processes in both the public and private healthcare sectors that use elements of HTA to varying extents to inform access and resource allocation decisions. Institutions performing HTAs or related activities in South Africa include the National and Provincial Departments of Health, National Treasury, National Health Laboratory Service, Council for Medical Schemes, medical scheme administrators, managed care organizations, academic or research institutions, clinical societies and associations, pharmaceutical and devices companies, private consultancies, and private sector hospital groups. Existing fragmented HTA processes should coordinate and conform to a standardized, fit-for-purpose process and structure that can usefully inform priority setting under NHI and for other decision makers. This transformation will require comprehensive and inclusive planning with dedicated funding and regulation, and provision of strong oversight mechanisms and leadership.
To achieve the elimination of the hepatitis C virus (HCV), sustained and sufficient levels of HCV testing is critical. The purpose of this study was to assess trends in testing and evaluate the effectiveness of strategies to diagnose people living with HCV. Data were from 12 primary care clinics in Victoria, Australia, that provide targeted services to people who inject drugs (PWID), alongside general health care. This ecological study spanned 2009–2019 and included analyses of trends in annual numbers of HCV antibody tests among individuals with no previous positive HCV antibody test recorded and annual test yield (positive HCV antibody tests/all HCV antibody tests). Generalised linear models estimated the association between count outcomes (HCV antibody tests and positive HCV antibody tests) and time, and χ2 test assessed the trend in test yield. A total of 44 889 HCV antibody tests were conducted 2009–2019; test numbers increased 6% annually on average [95% confidence interval (CI) 4–9]. Test yield declined from 2009 (21%) to 2019 (9%) (χ2P = <0.01). In more recent years (2013–2019) annual test yield remained relatively stable. Modest increases in HCV antibody testing and stable but high test yield within clinics delivering services to PWID highlights testing strategies are resulting in people are being diagnosed however further increases in the testing of people at risk of HCV or living with HCV may be needed to reach Australia's HCV elimination goals.
The Liouville equation is of fundamental importance in the derivation of continuum models for physical systems which are approximated by interacting particles. However, when particles undergo instantaneous interactions such as collisions, the derivation of the Liouville equation must be adapted to exclude non-physical particle positions, and include the effect of instantaneous interactions. We present the weak formulation of the Liouville equation for interacting particles with general particle dynamics and interactions, and discuss the results using two examples.
Dinosaur body fossil material is rare in Scotland, previously known almost exclusively from the Great Estuarine Group on the Isle of Skye. We report the first unequivocal dinosaur fossil from the Isle of Eigg, belonging to a Bathonian (Middle Jurassic) taxon of uncertain affinity. The limb bone NMS G.2020.10.1 is incomplete, but through a combination of anatomical comparison and osteohistology, we determine it most likely represents a stegosaur fibula. The overall proportions and cross-sectional geometry are similar to the fibulae of thyreophorans. Examination of the bone microstructure reveals a high degree of remodelling and randomly distributed longitudinal canals in the remaining primary cortical bone. This contrasts with the histological signal expected of theropod or sauropod limb bones, but is consistent with previous studies of thyreophorans, specifically stegosaurs. Previous dinosaur material from Skye and broadly contemporaneous sites in England belongs to this group, including Loricatosaurus and Sarcolestes and a number of indeterminate stegosaur specimens. Theropods such as Megalosaurus and sauropods such as Cetiosaurus are also known from these localities. Although we find strong evidence for a stegosaur affinity, diagnostic features are not observed on NMS G.2020.10.1, preventing us from referring it to any known genera. The presence of this large-bodied stegosaur on Eigg adds a significant new datapoint for dinosaur distribution in the Middle Jurassic of Scotland.
Nucleation is much more important for clay minerals than for other authigenic cements as clay crystals are very small, so that a very large number of clay crystals must be nucleated. The role of this difficult kinetic step in the diagenesis of sandstones has not been considered adequately as a ratedetermining process. The relationship between pore-fluid supersaturation and the rate of nucleation of a mineral is very different from the relationship between supersaturation and the rate of crystal enlargement; thus the two processes will act at very different rates. A diagenetic model that predicts claymineral formation but omits the nucleation stage may make unreliable predictions. This may account partially for the discrepancy between numerical simulations of CO2 injection that predict high degrees of reaction between the CO2 and the host rock, and the results of studies of natural analogues that have much lower degrees of reaction.
Geochemical and related studies have been made of near-surface sediments from the River Clyde estuary and adjoining areas, extending from Glasgow to the N, and W as far as the Holy Loch on the W coast of Scotland, UK. Multibeam echosounder, sidescan sonar and shallow seismic data, taken with core information, indicate that a shallow layer of modern sediment, often less than a metre thick, rests on earlier glacial and post-glacial sediments. The offshore Quaternary history can be aligned with onshore sequences, with the recognition of buried drumlins, settlement of muds from quieter water, probably behind an ice dam, and later tidal delta deposits. The geochemistry of contaminants within the cores also indicates shallow contaminated sediments, often resting on pristine pre-industrial deposits at depths less than 1m. The distribution of different contaminants with depth in the sediment, such as Pb (and Pb isotopes), organics and radionuclides, allow chronologies of contamination from different sources to be suggested. Dating was also attempted using microfossils, radiocarbon and 210Pb, but with limited success. Some of the spatial distribution of contaminants in the surface sediments can be related to grain-size variations. Contaminants are highest, both in absolute terms and in enrichment relative to the natural background, in the urban and inner estuary and in the Holy Loch, reflecting the concentration of industrial activity.
To describe the effect of universal methicillin-resistant Staphylococcus aureus (MRSA) decolonization therapy in a large intensive care unit (ICU) on the rates of MRSA cases and acquisitions in a UK hospital.
University Hospitals Birmingham (UHB) NHS Foundation Trust is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year.
A break-point time series analysis and kernel regression models were used to detect significant changes in the cumulative monthly numbers of MRSA bacteremia cases and acquisitions from April 2013 to August 2016 across the UHB system.
Prior to 2014, all ICU patients at UHB received universal MRSA decolonization therapy. In August 2014, UHB discontinued the use of universal decolonization due to published reports in the United Kingdom detailing the limited usefulness and cost-effectiveness of such an intervention. Break-point time series analysis of MRSA acquisition and bacteremia data indicated that break points were associated with the discontinuation and subsequent reintroduction of universal decolonization. Kernel regression models indicated a significant increase (P<.001) in MRSA acquisitions and bacteremia cases across UHB during the period without universal decolonization.
We suggest that routine decolonization for MRSA in a large ICU setting is an effective strategy to reduce the spread and incidence of MRSA across the whole hospital.
Employing a participatory arts-based research approach, we examined an innovative program from rural Ontario, Canada, designed to address social isolation among older people. Older socially isolated adults were matched to trained volunteers, where in dyads, the eight pairs created expressive art in their home setting over the course of 10 home visits. With thematic and narrative inquiry, we analysed the experiences and perceptions of the program leader, older participants, and older volunteers via their artistic creations, weekly logs, evaluations, and field notes. The findings reveal a successful intervention that positively influenced the well-being of older adult participants and older volunteers, especially in regards to relationships, personal development, and creating meaning as well as extending the intervention’s impact beyond the program’s duration. We also discuss opportunities for similar programs to inform policy and enable positive community-based health and social service responses to rural social isolation.
One of the most extensively studied aspects of phylogenetic tree shape is balance, which is the extent to which nodes divide a tree into clades of equal size. Several authors have stressed the importance of tree balance for understanding patterns of evolution. It has been remarked that paleontological studies commonly produce very unbalanced trees (also called pectinate cladograms or “Hennigian combs”). This claim is tested here by comparing the balance of 50 paleontological trees and 50 neontological trees, all taken from the recent literature. Each tree was reanalyzed from the published data matrix to ensure its accuracy. The results confirm that paleontological trees tend to be more imbalanced than neontological trees.
That paleontological trees are more imbalanced has been represented as a shortcoming of fossil data sets, but here it is argued that this is the expected result. Even under a simple Markovian model in which all speciations and extinctions occur randomly and with equal probability in all parts of the tree, trees based on taxa from a single time period (e.g., the present day) are generally more balanced than trees based on all taxa that ever existed within the clade. Computer simulation is used to calculate the expected balance and standard deviation of trees for up to 40 terminal taxa over the entire history of a model clade. The balance is measured using Colless's index, Ic, and the expected balance conforms well with published paleontological trees. The study underlines the difficulty of applying neontological tree statistics in paleontology.
Systematic collecting through the upper Wenlock (upper Homerian) and lower Ludlow (Gorstian and lowermost Ludfordian) Silurian rock succession of the Long Mountain, Powys, Wales, identifies some 48 chitinozoan species that distinguish four biozones, two subzones and an interregnum. Consideration of the chitinozoan biozones together with those of the graptolites enables a local three-fold subdivision of the late Homerian lundgreni graptolite Biozone, and the distinction of lower and upper intervals for the Gorstian incipiens graptolite Biozone. The base of the Ludlow Series in the Long Mountain more or less equates to the base of the Cingulochitina acme chitinozoan Biozone, although no key chitinozoan first or last appearance datums are associated with the series boundary itself. The new graptolite–chitinozoan biozonation allows enhanced correlation between upper Wenlock and lower Ludlow sedimentary deposits of the Lower Palaeozoic Welsh depositional basin and those of the palaeo-shelf in the stratotype Wenlock and Ludlow areas of Shropshire. Chitinozoans seem affected by the phenomena that caused the late Wenlock ‘Mulde extinction’ in graptolites but, with the final disappearance of 9 species and re-appearance of 11 species following an interval of overall low diversity, they seem to have suffered less severely than their macro-zooplanktonic contemporaries.
The seemingly inexorable expansion of global human population size, significant increases in the use of biofuel crops and the growing pressures of multifunctional land-use have intensified the need to improve crop productivity. The widespread cultivation of high-yielding genetically
modified (GM) crops could help to address these problems, although in doing so, steps must also be taken to ensure that any gene flow from these crops to wild or weedy recipients does not cause significant ecological harm. It is partly for this reason that new GM cultivars are invariably subjected to strict regulatory evaluation in order to assess the risks that each may pose to the environment. Regulatory bodies vary in their approach to decision-making, although all require access to large quantities of detailed information. Such an exhaustive case-by-case approach has been made tractable by the comparative simplicity of the portfolio of GM crops currently on the market, with four crops and two classes of traits accounting for almost all of the area under cultivation of GM crops. This simplified situation will change shortly, and will seriously complicate and potentially slow the evaluation process. Nowhere will the increased diversity of GM crops cause more difficulty to regulators than in those cases where there is a need to assess whether the transgene(s) will enhance fitness in a non-transgenic relative and thereafter cause ecological harm. Current practice to test this risk hypothesis focuses on attempting to detect increased fitness in the recipient. In this paper we explore the merits and shortcomings of this strategy, and investigate the scope for developing new approaches to streamline decision-making processes for transgenes that could cause unwanted ecological change.