OBJECTIVES
This study aimed to determine whether the myocardial T2relaxation time, determined using a black-blood magnetic resonance imaging (MRI) sequence, could predict acute heart transplant ...rejection.
BACKGROUND
The use of black-blood MRI sequences allows suppression of the confusing influence of blood signal when myocardial T2is calculated to detect myocardial edema.
METHODS
A total of 123 investigations, including cardiac MRI and myocardial biopsy, were performed 8 ± 11 months after heart transplantation. Myocardial T2was determined using an original inversion-recovery/spin-echo sequence.
RESULTS
A higher than normal T2(≥56 ms) allowed an accurate detection of the moderate acute rejections evidenced at baseline biopsy (≥International Society for Heart and Lung Transplantation grade 2): sensitivity, 89% and specificity, 70% (p < 0.0001). T2was increased in grade 2 (n = 11) compared with grade 0 (n = 49, p < 0.05), grade 1A (n = 34, p < 0.05) and grade 1B (n = 21, p < 0.05); T2was further increased in grade 3 (n = 8) compared with grade 2 (p < 0.05). In addition, in patients without rejection equal to or greater than grade 2 at baseline, a T2higher than normal (≥56 ms) was correlated with the subsequent occurrence of equal or greater than grade 2 rejection within the next three months: sensitivity 63% (12/19) and specificity 78% (64/82) (p = 0.001).
CONCLUSIONS
Myocardial T2, determined using a black-blood MRI sequence, is sufficiently sensitive to identify most of the moderate acute rejections documented with biopsy at the same time, but is also a predictor of the subsequent occurrence of such biopsy-defined rejections.
The accuracy of global water balance estimates is limited by the lack of observations at large scale and the uncertainties of model simulations. Global retrievals of terrestrial water storage (TWS) ...change and soil moisture (SM) from satellites provide an opportunity to improve model estimates through data assimilation. However, combining these two data sets is challenging due to the disparity in temporal and spatial resolution at both vertical and horizontal scale. For the first time, TWS observations from the Gravity Recovery and Climate Experiment (GRACE) and near‐surface SM observations from the Soil Moisture and Ocean Salinity (SMOS) were jointly assimilated into a water balance model using the Ensemble Kalman Smoother from January 2010 to December 2013 for the Australian continent. The performance of joint assimilation was assessed against open‐loop model simulations and the assimilation of either GRACE TWS anomalies or SMOS SM alone. The SMOS‐only assimilation improved SM estimates but reduced the accuracy of groundwater and TWS estimates. The GRACE‐only assimilation improved groundwater estimates but did not always produce accurate estimates of SM. The joint assimilation typically led to more accurate water storage profile estimates with improved surface SM, root‐zone SM, and groundwater estimates against in situ observations. The assimilation successfully downscaled GRACE‐derived integrated water storage horizontally and vertically into individual water stores at the same spatial scale as the model and SMOS, and partitioned monthly averaged TWS into daily estimates. These results demonstrate that satellite TWS and SM measurements can be jointly assimilated to produce improved water balance component estimates.
Key Points
GRACE TWS and SMOS SM observations were jointly assimilated for the first time
Joint assimilation improved water balance component estimates, especially in SM profile and groundwater
Joint assimilation performs better than assimilation of GRACE or SMOS only
Achieving a uniform extraction of soluble material from a porous matrix is a generic problem in various separation and filtration operations, with applications in the food processing, chemical and ...pharmaceutical industries. This paper describes models of fluid flow and transport of soluble material within a packed granular bed in the context of coffee extraction. Coffee extraction is described by diffusion of soluble material from particles of one or more representative sizes into fluid flowing through the packed bed. One-dimensional flow models are compared to computational fluid dynamics (CFD) models. A fine and a coarse coffee grind are considered. Model results are compared to experimental data for a packed cylindrical coffee bed and the influence of a change in geometry to a truncated cone is considered. Non-uniform flow in the truncated cone causes significant variation in the local extraction level. Coffee extraction levels during brewing are analysed using extraction maps and the degree of variation is represented on the industry standard coffee brewing control chart. A high variation in extraction yield can be expected to impart bitter flavours into the brew and thus is an important variable to quantify.
Information on SARS-CoV-2 in representative community surveillance is limited, particularly cycle threshold (Ct) values (a proxy for viral load).
We included all positive nose and throat swabs 26 ...April 2020 to 13 March 2021 from the UK's national COVID-19 Infection Survey, tested by RT-PCR for the N, S, and ORF1ab genes. We investigated predictors of median Ct value using quantile regression.
Of 3,312,159 nose and throat swabs, 27,902 (0.83%) were RT-PCR-positive, 10,317 (37%), 11,012 (40%), and 6550 (23%) for 3, 2, or 1 of the N, S, and ORF1ab genes, respectively, with median Ct = 29.2 (~215 copies/ml; IQR Ct = 21.9-32.8, 14-56,400 copies/ml). Independent predictors of lower Cts (i.e. higher viral load) included self-reported symptoms and more genes detected, with at most small effects of sex, ethnicity, and age. Single-gene positives almost invariably had Ct > 30, but Cts varied widely in triple-gene positives, including without symptoms. Population-level Cts changed over time, with declining Ct preceding increasing SARS-CoV-2 positivity. Of 6189 participants with IgG S-antibody tests post-first RT-PCR-positive, 4808 (78%) were ever antibody-positive; Cts were significantly higher in those remaining antibody negative.
Marked variation in community SARS-CoV-2 Ct values suggests that they could be a useful epidemiological early-warning indicator.
Department of Health and Social Care, National Institutes of Health Research, Huo Family Foundation, Medical Research Council UK; Wellcome Trust.
HIV posttreatment controllers are rare individuals who start antiretroviral therapy (ART), but maintain HIV suppression after treatment interruption. The frequency of posttreatment control and ...posttreatment interruption viral dynamics have not been well characterized.
Posttreatment controllers were identified from 14 studies and defined as individuals who underwent treatment interruption with viral loads ≤400 copies/mL at two-thirds or more of time points for ≥24 weeks. Viral load and CD4+ cell dynamics were compared between posttreatment controllers and noncontrollers.
Of the 67 posttreatment controllers identified, 38 initiated ART during early HIV infection. Posttreatment controllers were more frequently identified in those treated during early versus chronic infection (13% vs 4%, P < .001). In posttreatment controllers with weekly viral load monitoring, 45% had a peak posttreatment interruption viral load of ≥1000 copies/mL and 33% had a peak viral load ≥10000 copies/mL. Of posttreatment controllers, 55% maintained HIV control for 2 years, with approximately 20% maintaining control for ≥5 years.
Posttreatment control was more commonly identified amongst early treated individuals, frequently characterized by early transient viral rebound and heterogeneous durability of HIV remission. These results may provide mechanistic insights and have implications for the design of trials aimed at achieving HIV remission.
Designing Interfaces Using CWA Jenkins, Daniel P.; Stanton, Neville A.; Salmon, Paul M. ...
Cognitive Work Analysis: Coping with Complexity,
2009, 2008
Book Chapter
This chapter aims to investigate how well the cognitive work analysis framework can support the design and development of a military decisions support tool. The effects based approach has recently ...received a lot of attention within military and political circles. The approach advocates a move away from a sole focus on militaristic issues, to a consideration of the diplomatic, information, militaristic and economic effects of a decision at all levels of the command chain. In order to establish design recommendations a series of interfaces were developed. These developed interfaces were then evaluated via a set of controlled experiments were constructed in two phases. The first of these phases required participants to make decisions based upon the information displayed in previously generated interfaces. The second phase of experimentation, required participants to use a dynamic interface to make a decision based on a simple route selection paradigm.
This chapter describes an exercise intended to validate and extract key requirements for the Cognitive Work Analysis (CWA) software tool. The first phase of CWA, the Abstraction Hierarchy (AH), is ...used to describe the domain in event independent terms. Here the physical units and their capabilities are captured. The tool also has clear advantages over drafting software packages such as Microsoft Visio; the ability to pass information forward within the phases was extremely valuable in the process of expediting the documentation. The functions for the CAT were imported directly from the AH; the AH and the CAT products were reused in the Social Organisation and Cooperation Analysis phase. The process was successful in its main aim; the software tool was able to support the development of the required documentation and some clear recommendations for incremental changes were made for the tool improvement.
Interaction Design Jenkins, Daniel P.; Stanton, Neville A.; Salmon, Paul M. ...
Cognitive Work Analysis: Coping with Complexity,
2009, 2008
Book Chapter
This chapter introduces some of the basic principles behind the 'art' of interaction design and, more specifically, interface design. The process of designing a display can often be informed by ...considering the optimal representation for the different data sets. The interface design of a product has the ability to influence how it is interpreted and used, as either a functional or physical interface. Iconic forms are metaphoric representations of the data; they contain a semantic link to the source of their representation. Metaphoric references can be used to assist users in their development of mental models. Accurate mental models can have a significant impact on the time taken to learn how to use the product; requirements for formalised training; user satisfaction; and error rates. One common method of incorporating metaphoric references into a product is to design in a graphical representation of the previous, real world, situations that work in similar, predictable ways.
Applications of CWA in a Complex World Jenkins, Daniel P.; Stanton, Neville A.; Salmon, Paul M. ...
Cognitive Work Analysis: Coping with Complexity,
2009, 2008
Book Chapter
This chapter addresses how Cognitive Work Analysis (CWA) can be used for the purposes of analysis, informing design, and evaluation. The approach has been applied to two examples, a Helicopter ...Mission Planning System, and a battlefield command and control system. The first case study identifies opportunities for design improvements, the detailed look at the social organisation and cooperation analysis (SOCA) phase of the analysis also encourages the analyst and the designer to consider how the implications of; location, time and actor can influence the design of the system. The SOCA phase raises questions about the correct mix of cooperation and collaboration as well the suitability of distributed working practices. The second case study provides further description of the Work Domain Analysis phase in a new domain. The chapter also introduces the concept of using the Abstraction Hierarchy to generate measures of performance; these measures can be used in a survey of subject matter experts.
Application of CWA in Familiar Domains Jenkins, Daniel P.; Stanton, Neville A.; Salmon, Paul M. ...
Cognitive Work Analysis: Coping with Complexity,
2009, 2008
Book Chapter
This chapter discusses the application of Cognitive Work Analysis (CWA) in a simplistic, familiar domain. The case study uses the first three phases of CWA to explore the constraints governing the ...use of the Apple iPod. The analysis describes the constraints governing how activity is conducted in an actor independent way. The Work Domain Analysis describes the relationship between what the physical objects in the system can perform, and what the system is required to perform. The Control Task Analysis (ConTA) describes situations in which the iPod is constrained in its functionality, such as charging the battery on the move and uploading music whilst away from a computer. Strategies Analysis is used to look in more detail at known recurring activities. This stage of the analysis considers the tasks analysed in the ConTA phase and considers the strategies that are likely to be used to complete them.
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