753 research outputs found
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Project-based industries and craft-like production: structure, location, and performance
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The impact of greyscale inversion for nodule detection in an anthropomorphic chest phantom: a free-response observer study
Objective: The aim of this work was to assess the impact of greyscale inversion on nodule detection on poster- oanterior chest X-ray images. Previous work has attemp- ted this, with no consensus opinion formed. We assessed the value of “fast-flicking” between standard and inverted display modes for nodule detection.
Methods: Six consultant radiologists (with 5–32 years’ reporting experience) completed an observer task under the free-response paradigm. An anthropomorphic chest phantom was loaded with 50 different configurations of simulated nodules (1–4 nodules per case) measuring 5, 8, 10 and 12mm in spherical diameter; each configuration represented a single case. In addition, 25 cases contained no nodules. Images were displayed in three modes: (i) standard, (ii) inverted and (iii) fast-flicking between standard and inverted display modes. Each observer completed the study in a different order of display (i, ii, iii) using a calibrated 5-megapixel monitor. Nodules were localized with mouse clicks and ratings assigned using a 1–10 discrete slider-bar confidence scale. Rjafroc (Pitts- burgh, PA) was used for data analysis; differences in nodule detection performance were considered significant at 0.05.
Results: The observer-averaged weighted jackknife alter- native free-response receiver-operating characteristic figures of merit were 0.715 (standard), 0.684 (inverted) and 0.717 (fast-flicking). Random-reader fixed-case anal- ysis revealed no statistically significant difference be- tween any treatment pair [F(2,8) 5 1.22; p 5 0.345].
Conclusion: No statistically significant difference in nodule detection was found for the three display conditions.
Advances in knowledge: We have investigated the impact of fast-flicking between standard and inverted display modes for the detection of nodules. We found no benefit
Changes in plant species abundance alter the multifunctionality and functional space of heathland ecosystems
Though it is well established that species composition affects ecosystem function, the way in which species combine to control overall ecosystem functioning is still debated. In experimental mesocosms, we planted three functionally distinct dry-heath species in varying proportions and measured multiple ecosystem properties related to nutrient cycling and carbon storage (hereafter functions). Overall ecosystem functioning was described as the main axes of variation in ecosystem functioning (functional space) and the proportion of ecosystem functions at high levels; for example, fast carbon and nutrient cycling (cluster-based multifunctionality). The first functional space axis, related to nitrogen availability, was driven by plant species abundance, particularly that of legumes, which strongly affected many individual functions. The second, related to total plant biomass and woodiness, was mostly driven by the abundance of dwarf shrubs. Similarly, cluster-based multifunctionality was related to the initial abundance of all species, but particularly the legume. Interactions between species also affected ecosystem multifunctionality, but these effects were smaller in magnitude. These results indicate that species interactions could play a secondary role to species abundance and identity in driving the overall ecosystem functioning of heathlands, but also that axes of variation in functional space are clearly linked to plant functional composition
Synchronous bilateral Wilm's tumor in the adolescent and adult
Bilateral Wilms' tumor in the adolescent and adult is extremely rare, with only four previous cases reported. Theories as to the etiology of this entity and a review of the demographics, diagnosis, staging, and treatment of Wilms' tumor with emphasis on bilateral disease and the older patient are presented. Current approaches to the patient with an atypical presentation of Wilms' tumor can result in excellent results similar to those seen with the more typical presentation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47158/1/383_2004_Article_BF00185144.pd
Agricultural productivity in past societies: toward an empirically informed model for testing cultural evolutionary hypotheses
Agricultural productivity, and its variation in space and time, plays a fundamental role in many theories of human social evolution. However, we often lack systematic information about the productivity of past agricultural systems on a scale large enough to test these theories properly. The effect of climate on crop yields has received a great deal of attention resulting in a range of empirical and process-based models, yet the focus has primarily been on current or future conditions. In this paper, we argue for a “bottom-up” approach that estimates potential productivity based on information about the agricultural practices and technologies used in past societies. Of key theoretical interest is using this information to estimate the carrying high quality historical and archaeological information about past societies in order to infer the temporal and geographic patterns of change in agricultural productivity and potential. We discuss information we need to collect about past agricultural techniques and practices, and introduce a new databank initiative that we have developed for collating the best available historical and archaeological evidence. A key benefit of our approach lies in making explicit the steps in the estimation of past productivities and carrying capacities, and in being able to assess the effects of different modelling assumptions. This is undoubtedly an ambitious task, yet promises to provide important insights into fundamental aspects of past societies, enabling us to test more rigorously key hypotheses about human socio-cultural evolution
Managing Big Sagebrush in a Changing Climate
This publication identifies areas where big sagebrush populations are most and least vulnerable to climate change and demonstrates where continued investment in sagebrush conservation and restoration could have the most impact
Methods for automating the analysis of live-cell single-molecule FRET data
Single-molecule FRET (smFRET) is a powerful imaging platform capable of revealing dynamic changes in the conformation and proximity of biological molecules. The expansion of smFRET imaging into living cells creates both numerous new research opportunities and new challenges. Automating dataset curation processes is critical to providing consistent, repeatable analysis in an efficient manner, freeing experimentalists to advance the technical boundaries and throughput of what is possible in imaging living cells. Here, we devise an automated solution to the problem of multiple particles entering a region of interest, an otherwise labor-intensive and subjective process that had been performed manually in our previous work. The resolution of these two issues increases the quantity of FRET data and improves the accuracy with which FRET distributions are generated, increasing knowledge about the biological functions of the molecules under study. Our automated approach is straightforward, interpretable, and requires only localization and intensity values for donor and acceptor channel signals, which we compute through our previously published smCellFRET pipeline. The development of our automated approach is informed by the insights of expert experimentalists with extensive experience inspecting smFRET trajectories (displacement and intensity traces) from live cells. We test our automated approach against our recently published research on the metabotropic glutamate receptor 2 (mGluR2) and reveal substantial similarities, as well as potential shortcomings in the manual curation process that are addressable using the algorithms we developed here
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Accuracy and reproducibility of four T1 mapping sequences: a head-to-head comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE
Cardiovascular Magnetic Resonance Characterization of Mitral Valve Prolapse
ObjectivesThis study sought to develop cardiovascular magnetic resonance (CMR) diagnostic criteria for mitral valve prolapse (MVP) using echocardiography as the gold standard and to characterize MVP using cine CMR and late gadolinium enhancement (LGE)-CMR.BackgroundMitral valve prolapse is a common valvular heart disease with significant complications. Cardiovascular magnetic resonance is a valuable imaging tool for assessing ventricular function, quantifying regurgitant lesions, and identifying fibrosis, but its potential role in evaluating MVP has not been defined.MethodsTo develop CMR diagnostic criteria for MVP, characterize mitral valve morphology, we analyzed transthoracic echocardiography and cine CMR images from 25 MVP patients and 25 control subjects. Leaflet thickness, length, mitral annular diameters, and prolapsed distance were measured. Two- and three-dimensional LGE-CMR images were obtained in 16 MVP and 10 control patients to identify myocardial regions of fibrosis in MVP.ResultsWe found that a 2-mm threshold for leaflet excursion into the left atrium in the left ventricular outflow tract long-axis view yielded 100% sensitivity and 100% specificity for CMR using transthoracic echocardiography as the clinical gold standard. Compared with control subjects, CMR identified MVP patients as having thicker (3.2 ± 0.1 mm vs. 2.3 ± 0.1 mm) and longer (10.5 ± 0.5 mm/m2 vs. 7.1 ± 0.3 mm/m2) indexed posterior leaflets and larger indexed mitral annular diameters (27.8 ± 0.7 mm/m2 vs. 21.5 ± 0.5 mm/m2 for long axis and 22.9 ±0.7 mm/m2 vs. 17.8 ± 0.6 mm/m2 for short axis). In addition, we identified focal regions of LGE in the papillary muscles suggestive of fibrosis in 10 (63%) of 16 MVP patients and in 0 of 10 control subjects. Papillary muscle LGE was associated with the presence of complex ventricular arrhythmias in MVP patients.ConclusionsCardiovascular magnetic resonance image can identify MVP by the same echocardiographic criteria and can identify myocardial fibrosis involving the papillary muscle in MVP patients. Hyperenhancement of papillary muscles on LGE is often present in a subgroup of patients with complex ventricular arrhythmias
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