This report follows a series of seven first-level Heavy Vehicle Simulator (HVS) testing reports, two laboratory reports on shear and fatigue testing, a forensic investigation report, and a report on ...the backcalculation of deflection measurements, all of which document an investigation undertaken to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete. It presents the findings from a detailed analysis of the laboratory fatigue and shear results, and a series of simulations using CalME mechanistic-empirical design software and continuum damage mechanics implemented using a finite element method. The work was conducted by the University of California Pavement Research Center (UCPRC) as part of Partnered Pavement Research Center Strategic Plan Item 4.10: âeurooeDevelopment of Improved Rehabilitation Designs for Reflective Cracking.âeuro This work was originally requested by the Caltrans/Industry Rubber Asphalt Concrete Task Group (RACTG) to compare the performance of one set of examples of thin overlays of cracked asphalt pavement containing different types of binders modified with recycled tire rubber. This work, included as Appendix H of the Rubber Modified Binder Pilot Projects Review prepared by the RACTG is part of a more comprehensive work plan prepared by the Task Group that included evaluation of pilot projects and construction and monitoring of field test sections (undertaken by Caltrans). The objective of this UCPRC project will be met after completion of the following four tasks: 1. Develop improved mechanistic models of reflective cracking in California, 2. Calibrate and verify these models using laboratory and HVS testing, 3. Evaluate the most effective strategies for reflective cracking, and 4. Provide recommendations for reflective cracking strategies. This report addresses all the tasks and consists of six main chapters. Chapter 2 provides an overview of the HVS testing program for the study. Chapter 3 summarizes a second-level analysis of the laboratory fatigue and shear test results. Chapter 4 discusses mechanistic-empirical modeling and simulations of the HVS results using CalME software, which is currently being developed for Caltrans by the UCPRC. Chapter 5 discusses modeling and simulations using continuum damage mechanics implemented using finite-element models. Chapter 6 lists key findings of the study, and provides recommendations for implementation.
This report contains a summary of the laboratory fatigue tests on mixes used as overlays on the Reflective Cracking Study Test Track at the Richmond Field Station. Evaluation of the results of the ...laboratory study on fatigue response of the overlay mixes reported herein included the effects of mix temperatures, air-void content, aging, mixing and compaction conditions, aggregate gradation, and time of loading. Five binders were assessed, namely AR4000, asphalt rubber (Type G), and three modified binders, termed MB4, MB15, and MAC15. A full factorial considering all the variables required a total of 1,440 tests. This was reduced to 172 tests to accommodate time and fund constraints. Based on the fatigue test results for the mixes used in the overlay experiment, mix rankings for initial stiffness and fatigue life are, from highest to lowest, as follows: Initial stiffness Fatigue life AR4000-D MB4-G RAC-G MB15-G and MAC15-G MAC15-G RAC-G MB4-G and MB15-G AR4000-D Until a range of pavement types and environments are evaluated in the 2nd Level Analysis, only a general indication of the relative performance of the modified binders can be deduced. It would appear that the MB4, MB15, and MAC15 binders used in gap-graded mixes as overlays on existing cracked asphalt concrete pavements should provide comparable lives (at least) to RAC-G mixes when used in comparable thicknesses in thin layers (less than about 60 mm). Recommendations for the use of MB4, MB15 and MAC15 binders in thicker layers and as densegraded mixes await the results of the shear test results and pavement performance analyses.
Throughout the social, medical and other sciences the importance of understanding complex hierarchical data structures is well understood. Multilevel modelling is now the accepted statistical ...technique for handling such data and is widely available in computer software packages. A thorough understanding of these techniques is therefore important for all those working in these areas. This new edition of Multilevel Statistical Models brings these techniques together, starting from basic ideas and illustrating how more complex models are derived. Bayesian methodology using MCMC has been extended along with new material on smoothing models, multivariate responses, missing data, latent normal transformations for discrete responses, structural equation modeling and survival models.Key Features:Provides a clear introduction and a comprehensive account of multilevel models.New methodological developments and applications are explored.Written by a leading expert in the field of multilevel methodology.Illustrated throughout with real-life examples, explaining theoretical concepts.This book is suitable as a comprehensive text for postgraduate courses, as well as a general reference guide. Applied statisticians in the social sciences, economics, biological and medical disciplines will find this book beneficial.
Background
Acute pulmonary embolism (APE) is a major cause of acute morbidity and mortality. APE results in long‐term morbidity in up to 50% of survivors, known as post‐pulmonary embolism (post‐PE) ...syndrome.
APE can be classified according to the short‐term (30‐day) risk of mortality, based on a variety of clinical, imaging and laboratory findings. Most mortality and morbidity is concentrated in high‐risk (massive) and intermediate‐risk (submassive) APE. The first‐line treatment for APE is systemic anticoagulation.
High‐risk (massive) APE accounts for less than 10% of APE cases and is a life‐threatening medical emergency, requiring immediate reperfusion treatment to prevent death. Systemic thrombolysis is the recommended treatment for high‐risk (massive) APE. However, only a minority of the people affected receive systemic thrombolysis, due to comorbidities or the 10% risk of major haemorrhagic side effects. Of those who do receive systemic thrombolysis, 8% do not respond in a timely manner. Surgical pulmonary embolectomy is an alternative reperfusion treatment, but is not widely available.
Intermediate‐risk (submassive) APE represents 45% to 65% of APE cases, with a short‐term mortality rate of around 3%. Systemic thrombolysis is not recommended for this group, as major haemorrhagic complications outweigh the benefit. However, the people at higher risk within this group have a short‐term mortality of around 12%, suggesting that anticoagulation alone is not an adequate treatment. Identification and more aggressive treatment of people at intermediate to high risk, who have a more favourable risk profile for reperfusion treatments, could reduce short‐term mortality and potentially reduce post‐PE syndrome.
Catheter‐directed treatments (catheter‐directed thrombolysis and catheter embolectomy) are minimally invasive reperfusion treatments for high‐ and intermediate‐risk APE. Catheter‐directed treatments can be used either as the primary treatment or as salvage treatment after failure of systemic thrombolysis. Catheter‐directed thrombolysis administers 10% to 20% of the systemic thrombolysis dose directly into the thrombus in the lungs, potentially reducing the risks of haemorrhagic side effects. Catheter embolectomy mechanically removes the thrombus without the need for thrombolysis, and may be useful for people with contraindications for thrombolysis.
Currently, the benefits of catheter‐based APE treatments compared with existing medical and surgical treatment are unclear despite increasing adoption of catheter treatments by PE response teams. This review examines the evidence for the use of catheter‐directed treatments in high‐ and intermediate‐risk APE. This evidence could help guide the optimal treatment strategy for people affected by this common and life‐threatening condition.
Objectives
To assess the effects of catheter‐directed therapies versus alternative treatments for high‐risk (massive) and intermediate‐risk (submassive) APE.
Search methods
We used standard, extensive Cochrane search methods. The latest search was 15 March 2022.
Selection criteria
We included randomised controlled trials (RCTs) of catheter‐directed therapies for the treatment of high‐risk (massive) and intermediate‐risk (submassive) APE. We excluded catheter‐directed treatments for non‐PE. We applied no restrictions on participant age or on the date, language or publication status of RCTs.
Data collection and analysis
We used standard Cochrane methods. The main outcomes were all‐cause mortality, treatment‐associated major and minor haemorrhage rates based on two established clinical definitions, recurrent APE requiring retreatment or change to a different APE treatment, length of hospital stay, and quality of life. We used GRADE to assess certainty of evidence for each outcome.
Main results
We identified one RCT (59 participants) of (ultrasound‐augmented) catheter‐directed thrombolysis for intermediate‐risk (submassive) APE.
We found no trials of any catheter‐directed treatments (thrombectomy or thrombolysis) in people with high‐risk (massive) APE or of catheter‐based embolectomy in people with intermediate‐risk (submassive) APE.
The included trial compared ultrasound‐augmented catheter‐directed thrombolysis with alteplase and systemic heparinisation versus systemic heparinisation alone. In the treatment group, each participant received an infusion of alteplase 10 mg or 20 mg over 15 hours. We identified a high risk of selection and performance bias, low risk of detection and reporting bias, and unclear risk of attrition and other bias. Certainty of evidence was very low because of risk of bias and imprecision.
By 90 days, there was no clear difference in all‐cause mortality between the treatment group and control group. A single death occurred in the control group at 20 days after randomisation, but it was unrelated to the treatment or to APE (odds ratio (OR) 0.31, 95% confidence interval (CI) 0.01 to 7.96; 59 participants).
By 90 days, there were no episodes of treatment‐associated major haemorrhage in either the treatment or control group. There was no clear difference in treatment‐associated minor haemorrhage between the treatment and control group by 90 days (OR 3.11, 95% CI 0.30 to 31.79; 59 participants).
By 90 days, there were no episodes of recurrent APE requiring retreatment or change to a different APE treatment in the treatment or control group.
There was no clear difference in the length of mean total hospital stay between the treatment and control groups. Mean stay was 8.9 (standard deviation (SD) 3.4) days in the treatment group versus 8.6 (SD 3.9) days in the control group (mean difference 0.30, 95% CI −1.57 to 2.17; 59 participants).
The included trial did not investigate quality of life measures.
Authors' conclusions
There is a lack of evidence to support widespread adoption of catheter‐based interventional therapies for APE. We identified one small trial showing no clear differences between ultrasound‐augmented catheter‐directed thrombolysis with alteplase plus systemic heparinisation versus systemic heparinisation alone in all‐cause mortality, major and minor haemorrhage rates, recurrent APE and length of hospital stay. Quality of life was not assessed.
Multiple small retrospective case series, prospective patient registries and single‐arm studies suggest potential benefits of catheter‐based treatments, but they provide insufficient evidence to recommend this approach over other evidence‐based treatments.
Researchers should consider clinically relevant primary outcomes (e.g. mortality and exercise tolerance), rather than surrogate markers (e.g. right ventricular to left ventricular (RV:LV) ratio or thrombus burden), which have limited clinical utility. Trials must include a control group to determine if the effects are specific to the treatment.
Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been ...developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability.
Social eating initiatives are a mode of food provisioning and eating that have become increasingly popular in the UK. These organisations provide a menu of low-cost meals prepared using food ...surpluses and deliberately serve food communally to improve social inclusion. Although these community initiatives have grown rapidly in popularity, research into their value from the perspective of participants is currently limited. This article presents data from a concurrent multi-method study conducted across multiple sites of the Nottingham Social Eating Network to explain the emergence of these novel social configurations. The results show this form of commensality, or group eating practice, is not simply a consequence of reducing food waste or food insecurity. Instead these initiatives are enacted through a series of intersecting social practices, which include: the restructuration of the shared mealtime; alimentary contribution; and performances of care. The findings provide important insights into the values expressed in these emergent initiatives and are therefore useful for framing social eating in public policy.
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