282 research outputs found
Historical trends of PBDEs and HBCDs in sediment cores from Sydney estuary, Australia
This paper presents the first historical data on the occurrence of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDs) in estuarine sediment from Australia. Sediment cores and surficial sediment samples were collected from four locations within Sydney estuary, Australia. Large increases in concentrations were observed for all compounds between 1980 and 2014, especially for BDE-209 (representative usage of Deca-BDE commercial mixture), which was found in surficial sediment at an average concentration of 42 ng/g thy wt (21-65 ng/g dry wt). PBDE congeners representative of both the Penta- and Octa-BDE commercial mixtures (Sigma 6PBDEs) were also found in their highest concentrations in surficial sediments (average: 1.3 ng/g dry wt; range: 0.65-2.5 ng/g dry wt). PBDE concentrations in surficial sediments were relatively high when compared with those presented in the available literature. This suggests that their input into the Sydney estuary has not decreased since their bans almost a decade earlier. After a sharp increase in the 1990s, HBCD concentrations peaked at an average of 3.5 ng/g dry wt (1.8-53 ng/g dry wt) in surficial samples. With global legislation on HBCDs allowing its usage for the next 10 years, it is expected that its input into the estuary is likely to continue. (C) 2015 Elsevier B.V. All rights reserved
A pitfall in the reconstruction of fibre ODFs using spherical deconvolution of diffusion MRI data
Diffusion weighted ( DW ) MRI facilitates non-invasive quantification of tissue microstructure and, in combination with appropriate signal processing, three-dimensional estimates of fibrous orientation. In recent years, attention has shifted from the diffusion tensor model, which assumes a unimodal Gaussian diffusion displacement profile to recover fibre orientation ( with various well-documented limitations ), towards more complex high angular resolution diffusion imaging ( HARDI ) analysis techniques. Spherical deconvolution ( SD ) approaches assume that the fibre orientation density function ( fODF ) within a voxel can be obtained by deconvolving a ‘common’ single fibre response function from the observed set of DW signals. In practice, this common response function is not known a priori and thus an estimated fibre response must be used. Here the establishment of this single-fibre response function is referred to as ‘calibration’. This work examines the vulnerability of two different SD approaches to inappropriate response function calibration: ( 1 ) constrained spherical harmonic deconvolution ( CSHD )—a technique that exploits spherical harmonic basis sets and ( 2 ) damped Richardson–Lucy ( dRL ) deconvolution—a technique based on the standard Richardson–Lucy deconvolution. Through simulations, the impact of a discrepancy between the calibrated diffusion profiles and the observed ( ‘Target’ ) DW-signals in both single and crossing-fibre configurations was investigated. The results show that CSHD produces spurious fODF peaks ( consistent with well known ringing artefacts ) as the discrepancy between calibration and target response increases, while dRL demonstrates a lower over-all sensitivity to miscalibration ( with a calibration response function for a highly anisotropic fibre being optimal ). However, dRL demonstrates a reduced ability to resolve low anisotropy crossing-fibres compared to CSHD. It is concluded that the range and spatial-distribution of expected single-fibre anisotropies within an image must be carefully considered to ensure selection of the appropriate algorithm, parameters and calibration. Failure to choose the calibration response function carefully may severely impact the quality of any resultant tractography
Identification, surveillance and management of Aedes vexans in a flooded river valley in Nottinghamshire, United Kingdom
Mapping spatial dimensions of Wilderness recreation outcomes: a study of overnight users
Grand Teton National Park (GRTE) is a popular mountain recreation destination which, like many National Park Service (NPS) units, has experienced a significant increase in visitation in recent years, with total visits increasing by 27% between 2014 and 2017 (NPS 2020). Particularly popular within GRTE is the String and Leigh Lakes (SLL) area, which is a favoured alpine destination for numerous day-use recreation activities and also an important starting point for backcountry and overnight recreational users within GRTE’s Recommended Wilderness. To better understand the visitor experience of overnight backcountry recreationists in the SLL area, data were collected using novel public participatory geographic information systems (PPGIS) during the summer of 2018. PPGIS data were used to identify the locations in which overnight recreationists experienced positive and negative recreation outcomes. Results indicate that they experience more positive outcomes within the Recommended Wilderness, away from high-density, trailhead-proximate areas outside the Recommended Wilderness. Findings also indicate that overnight users experience crowding and conflict more outside of the Recommended Wilderness than elsewhere on their backcountry trip. While this may seem intuitive, these are some of the first empirical results spatially contextualizing backcountry visitor outcomes in a popular national park. The findings thus provide managers with a visitor experience baseline that can be monitored and adaptively managed in the future
Perspectives on local government’s place in federal systems and central–local relations
To expand on the themes identified by Tomas Hachard’s paper 'Capacity, voice and opportunity: advancing municipal engagement in Canadian federal relations', the Journal commissioned six personal ‘perspectives’ from a diverse group of other Commonwealth countries – Australia, India, New Zealand, Nigeria, South Africa and the United Kingdom. This replicated the model adopted in Issue 26 for Zack Taylor’s paper on 'Regionalism from above: intergovernmental relations in Canadian metropolitan governance'. Similarly, the purpose was to establish a broader picture of issues and trends across the Commonwealth, rather than ‘review’ Hachard’s work
Author Correction: Possible role of L-form switching in recurrent urinary tract infection.
An amendment to this paper has been published and can be accessed via a link at the top of the paper
The impact of time to death in donors after circulatory death on recipient outcome in simultaneous pancreas-kidney transplantation
\ua9 2024 The AuthorsThe time to arrest donors after circulatory death is unpredictable and can vary. This leads to variable periods of warm ischemic damage prior to pancreas transplantation. There is little evidence supporting procurement team stand-down times based on donor time to death (TTD). We examined what impact TTD had on pancreas graft outcomes following donors after circulatory death (DCD) simultaneous pancreas-kidney transplantation. Data were extracted from the UK transplant registry from 2014 to 2022. Predictors of graft loss were evaluated using a Cox proportional hazards model. Adjusted restricted cubic spline models were generated to further delineate the relationship between TTD and outcome. Three-hundred-and-seventy-five DCD simultaneous kidney-pancreas transplant recipients were included. Increasing TTD was not associated with graft survival (adjusted hazard ratio HR 0.98, 95% confidence interval 0.68-1.41, P = .901). Increasing asystolic time worsened graft survival (adjusted hazard ratio 2.51, 95% confidence interval 1.16-5.43, P = .020). Restricted cubic spline modeling revealed a nonlinear relationship between asystolic time and graft survival and no relationship between TTD and graft survival. We found no evidence that TTD impacts pancreas graft survival after DCD simultaneous pancreas-kidney transplantation; however, increasing asystolic time was a significant predictor of graft loss. Procurement teams should attempt to minimize asystolic time to optimize pancreas graft survival rather than focus on the duration of TTD
Detailing patient specific modelling to aid clinical decision-making
The anatomy of the craniofacial skeleton has been described through the aid of dissection identifying hard and soft tissue structures. Although the macro and microscopic investigation of internal facial tissues have provided invaluable information on constitution of the tissues it is important to inspect and model facial tissues in the living individual. Detailing the form and function of facial tissues will be invaluable in clinical diagnoses and planned corrective surgical interventions such as management of facial palsies and craniofacial disharmony/anomalies.
Recent advances in lower-cost, non-invasive imaging and computing power (surface scanning, Cone Beam Computerized Tomography (CBCT) and Magnetic Resonance (MRI)) has enabled the ability to capture and process surface and internal structures to a high resolution. The three-dimensional surface facial capture has enabled characterization of facial features all of which will influence subtleties in facial movement and surgical planning.
This chapter will describe the factors that influence facial morphology in terms of gender and age differences, facial movement—surface and underlying structures, modeling based on average structures, orientation of facial muscle fibers, biomechanics of movement—proof of principle and surgical intervention
Selective strategy for solid sorbent replacement in CCS
An innovative method for sorbent replacement in the looping of a generic solid sorbent for post-combustion carbon capture and sequestration (CCS) is introduced. First, the standard replacement method is revisited with some original results presented. A new strategy is then modeled, aimed at selectively replacing the material as it degrades. This method exploits the density difference, after adsorption, between relatively fresh, CO2-laden sorbent and relatively degraded material, with small residual adsorption capacity. The model is then applied to values of degradation rate within the experimental range available in scientific literature for silica-supported amines (SSA). The selective removal strategy ideally allows a saving of 37% of the sorbent with respect to the standard, undifferentiated replacement considered in first place, while keeping the same adsorptive capacity of the system
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