291 research outputs found
Conjecturing-Based Computational Discovery of Patterns in Data
Modern machine learning methods are designed to exploit complex patterns in
data regardless of their form, while not necessarily revealing them to the
investigator. Here we demonstrate situations where modern machine learning
methods are ill-equipped to reveal feature interaction effects and other
nonlinear relationships. We propose the use of a conjecturing machine that
generates feature relationships in the form of bounds for numerical features
and boolean expressions for nominal features that are ignored by machine
learning algorithms. The proposed framework is demonstrated for a
classification problem with an interaction effect and a nonlinear regression
problem. In both settings, true underlying relationships are revealed and
generalization performance improves. The framework is then applied to
patient-level data regarding COVID-19 outcomes to suggest possible risk
factors.Comment: 25 pages, 6 figure
Nitrogen Management in a Maize-Groundnut Crop Rotation of Humid Tropics: Effect on N2O Emission
Development of appropriate land management
techniques to attain sustainability and increase
the N use efficiency of crops in the tropics has
been gaining momentum. The nitrous oxides
(N2Os) affect global climate change and its contribution
from N and C management systems is
of great significance. Thus, N transformations and
N2O emission during maize-groundnut crop rotation
managed with various N sources were studied.
Accumulation of nitrate (NO3
–) and its disappearance
happened immediately after addition of
various N sources, showing liming effect. The mineral
N retained for 2–4 weeks depending on the
type and amount of N application. The chicken
manure showed rapid nitrification in the first week
after application during the fallow period, leading
to a maximum N2O flux of 9889 μg N2O-N m–2 day–
1. The same plots showed a residual effect by
emitting the highest N2O (4053 μg N2O-N m–2 day–
1) during maize cultivation supplied with a halfrate
of N fertilizer. Application of N fertilizer only
or in combination with crop residues exhibited
either lowered fluxes or caused a sink during the
groundnut and fallow periods due to small availability
of substrates and/or low water-filled pore
space (<40%). The annual N2O emission ranged
from 1.41 to 3.94 kg N2O-N ha–1; the highest was estimated from the chicken manure plus crop residues
and half-rate of inorganic N-amended plots.
Results indicates a greater influence of chicken
manure on the N transformations and thereby N2O
emission
Community shifts and carbon translocation within metabolically-active rhizosphere microorganisms in grasslands under elevated CO<sub>2</sub>
International audienceThe aim of this study was to identify the microbial communities that are actively involved in the assimilation of rhizosphere-C and are most sensitive in their activity to elevated atmospheric CO2 in a temperate semi-natural low-input grassland ecosystem. For this, we analyzed 13C signatures in microbial biomarker phospholipid fatty acids (PLFA) from an in-situ 13CO2 pulse-labeling experiment in the Giessen Free Air Carbon dioxide Enrichment grasslands (GiFACE, Germany) exposed to ambient and elevated (i.e. 50% above ambient) CO2 concentrations. Short-term 13C PLFA measurements at 3 h and 10 h after the pulse-labeling revealed very little to no 13C enrichment after 3 h in biomarker PLFAs and a much greater incorporation of new plant-C into fungal compared to bacterial PLFAs after 10 h. After a period of 11 months following the pulse-labeling experiment, the 13C enrichment of fungal PLFAs was still largely present but had decreased, while bacterial PLFAs were much more enriched in 13C compared to a few hours after the pulse-labeling. These results imply that new rhizodeposit-C is rapidly processed by fungal communities and only much later by the bacterial communities, which we attributed to either a fungal-mediated translocation of rhizosphere-C from the fungal to bacterial biomass or a preferential bacterial use of dead root or fungal necromass materials as C source over the direct utilization of fresh root-exudate C in these N-limited grassland ecosystems. Elevated CO2 caused an increase in the proportional 13C enrichment (relative to the universal biomarker 16:0) of the arbuscular mycorrhizal fungal biomarker PLFA 16:1?5 and one gram-positive bacterial biomarker PLFA i16:0, but a decrease in the proportional 13C enrichment of 18:1?9c, a commonly used though questionable fungal biomarker PLFA. This suggests enhanced fungal rhizodeposit-C assimilation only by arbuscular mycorrhizal fungal species under elevated CO2
Breath analysis by gas chromatography-mass spectrometry and electronic nose to screen for pleural mesothelioma : a cross-sectional case-control study
Rationale: Malignant pleural mesothelioma (MPM) is mainly caused by previous exposure to asbestos fibers and has a poor prognosis. Due to a long latency period between exposure and diagnosis, MPM incidence is expected to peak between 2020-2025. Screening of asbestos-exposed individuals is believed to improve early detection and hence, MPM management. Recent developments focus on breath analysis for screening since breath contains volatile organic compounds (VOCs) which reflect the cell’s metabolism.
Objectives: The goal of this cross-sectional, case-control study is to identify VOCs in exhaled breath of MPM patients with gas chromatography-mass spectrometry (GC-MS) and to assess breath analysis to screen for MPM using an electronic nose (eNose).
Methods: Breath and background samples were taken from 64 subjects: 16 healthy controls (HC), 19 asymptomatic former asbestos-exposed (AEx) individuals, 15 patients with benign asbestos-related diseases (ARD) and 14 MPM patients. Samples were analyzed with both GC-MS and eNose.
Results: Using GC-MS, AEx individuals were discriminated from MPM patients with 97% accuracy, with diethyl ether, limonene, nonanal, methylcyclopentane and cyclohexane as important VOCs. This was validated by eNose analysis. MPM patients were discriminated from AEx+ARD participants by GC-MS and eNose with 94% and 74% accuracy, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 91%, 82%, 100% for GC-MS and 82%, 55%, 82%, 55% for eNose, respectively.
Conclusion: This study shows accurate discrimination of patients with MPM from asymptomatic asbestos-exposed persons at risk by GC-MS and eNose analysis of exhaled VOCs and provides proof-of-principle of breath analysis for MPM screening
Automated conjecturing II : chomp and reasoned game play
We demonstrate the use of a program that generates conjectures about positions of the combinatorial game Chomp—explanations of why certain moves are bad. These could be used in the design of a Chomp-playing program that gives reasons for its moves. We prove one of these Chomp conjectures—demonstrating that our conjecturing program can produce genuine Chomp knowledge.
The conjectures are generated by a general purpose conjecturing program that was previously and successfully used to generate mathematical conjectures. Our program is initialized with Chomp invariants and example game boards—the conjectures take the form of invariant-relation statements interpreted to be true for all board positions of a certain kind. The conjectures describe a theory of Chomp positions.
The program uses limited, natural input and suggests how theories generated on-the-fly might be used in a variety of situations where decisions—based on reasons—are required
Impact of critical illness and withholding of early parenteral nutrition in the pediatric intensive care unit on long-term physical performance of children:a 4-year follow-up of the PEPaNIC randomized controlled trial
Background: Many critically ill children face long-term developmental impairments. The PEPaNIC trial attributed part of the problems at the level of neurocognitive and emotional/behavioral development to early use of parenteral nutrition (early-PN) in the PICU, as compared with withholding it for 1 week (late-PN). Insight in long-term daily life physical functional capacity after critical illness is limited. Also, whether timing of initiating PN affects long-term physical function of these children remained unknown. Methods: This preplanned follow-up study of the multicenter PEPaNIC randomized controlled trial subjected 521 former critically ill children (253 early-PN, 268 late-PN) to quantitative physical function tests 4 years after PICU admission in Leuven or Rotterdam, in comparison with 346 age- and sex-matched healthy children. Tests included handgrip strength measurement, timed up-and-go test, 6-min walk test, and evaluation of everyday overall physical activity with an accelerometer. We compared these functional measures for the former critically ill and healthy children and for former critically ill children randomized to late-PN versus early-PN, with multivariable linear or logistic regression analyses adjusting for risk factors. Results: As compared with healthy children, former critically ill children showed less handgrip strength (p < 0.0001), completed the timed up-and-go test more slowly (p < 0.0001), walked a shorter distance in 6 min (p < 0.0001) during which they experienced a larger drop in peripheral oxygen saturation (p ≤ 0.026), showed a lower energy expenditure (p ≤ 0.024), performed more light and less moderate physical activity (p ≤ 0.047), and walked fewer steps per day (p = 0.0074). Late-PN as compared with early-PN did not significantly affect these outcomes. Conclusions: Four years after PICU admission, former critically ill children showed worse physical performance as compared with healthy children, without impact of timing of supplemental PN in the PICU. This study provides further support for de-implementing the early use of PN in the PICU. Trial registration ClinicalTrials.gov, NCT01536275; registered on February 22, 2012.</p
Purification and Characterization of a [beta]-D-Xylosidase and an Endo-Xylanase from Wheat Flour
Can community-based peer support promote health literacy and reduce inequalities? A realist review.
Background
Community-based peer support (CBPS) has been proposed as a potentially promising approach to improve health literacy (HL) and reduce health inequalities. Peer support, however, is described as a public health intervention in search of a theory, and as yet there are no systematic reviews exploring why or how peer support works to improve HL.
Objective
To undertake a participatory realist synthesis to develop a better understanding of the potential for CBPS to promote better HL and reduce health inequalities.
Data sources
Qualitative evidence syntheses, conceptual reviews and primary studies evaluating peer-support programmes; related studies that informed theoretical or contextual elements of the studies of interest were included. We conducted searches covering 1975 to October 2011 across Scopus, Global Health (including MEDLINE), ProQuest Dissertations & Theses database (PQDT) [including the Education Resources Information Center (ERIC) and Social Work Abstracts], The King’s Fund Database and Web of Knowledge, and the Institute of Development Studies supplementary strategies were used for the identification of grey literature. We developed a new approach to searching called ‘cluster searching’, which uses a variety of search techniques to identify papers or other research outputs that relate to a single study.
Study eligibility criteria
Studies written in English describing CBPS research/evaluation, and related papers describing theory, were included.
Study appraisal and synthesis methods
Studies were selected on the basis of relevance in the first instance. We first analysed within-programme articulation of theory and appraised for coherence. Cross-programme analysis was used to configure relationships among context, mechanisms and outcomes. Patterns were then identified and compared with theories relevant to HL and health inequalities to produce a middle-range theory.
Results
The synthesis indicated that organisations, researchers and health professionals that adopt an authoritarian design for peer-support programmes risk limiting the ability of peer supporters (PSs) to exercise autonomy and use their experiential knowledge to deliver culturally tailored support. Conversely, when organisations take a negotiated approach to codesigning programmes, PSs are enabled to establish meaningful relationships with people in socially vulnerable groups. CBPS is facilitated when organisations prioritise the importance of assessing community needs; investigate root causes of poor health and well-being; allow adequate time for development of relationships and connections; value experiential cultural knowledge; and share power and control during all stages of design and implementation. The theory now needs to be empirically tested via further primary research.
Limitations
Analysis and synthesis were challenged by a lack of explicit links between peer support for marginalised groups and health inequalities; explicitly stated programme theory; inconsistent reporting of context and mechanism; poor reporting of intermediate process outcomes; and the use of theories aimed at individual-level behaviour change for community-based interventions.
Conclusions
Peer-support programmes have the potential to improve HL and reduce health inequalities but potential is dependent upon the surrounding equity context. More explicit empirical research is needed, which establishes clearer links between peer-supported HL and health inequalities
Community engagement to enhance trust between Gypsy/Travellers, and maternity, early years’ and child dental health services: protocol for a multimethod exploratory study
Gypsy/Travellers have poor health and experience discrimination alongside structural and cultural barriers when accessing health services and consequently may mistrust those services. Our study aims to investigate which approaches to community engagement are most likely to be effective at enhancing trust between Gypsy/Travellers and mainstream health services.
Methods
This multi-method 30-month study, commenced in June 2015, and comprises four stages.
1.
Three related reviews: a) systematic review of Gypsy/Travellers’ access to health services; b) systematic review of reviews of how trust has been conceptualised within healthcare; c) realist synthesis of community engagement approaches to enhance trust and increase Gypsy/Travellers’ participation in health services. The reviews will consider any economic literature;
2.
Online consultation with health and social care practitioners, and civil society organisations on existing engagement activities, including perceptions of barriers and good practice;
3.
Four in-depth case studies of different Gypsy/Traveller communities, focusing on maternity, early years and child dental health services. The case studies include the views of 32–48 mothers of pre-school children, 32–40 healthcare providers and 8–12 informants from third sector organisations.
4.
Two stakeholder workshops exploring whether policy options are realistic, sustainable and replicable.
Case study data will be analysed thematically informed by the evaluative framework derived from the realist synthesis in stage one.
The main outputs will be: a) an evaluative framework of Gypsy/Travellers’ engagement with health services; b) recommendations for policy and practice; c) evidence on which to base future implementation strategies including estimation of costs.
Discussion
Our novel multi-method study seeks to provide recommendations for policy and practice that have potential to improve uptake and delivery of health services, and to reduce lifetime health inequalities for Gypsy/Travellers. The findings may have wider resonance for other marginalised populations. Strengths and limitations of the study are discussed
Atypical vessels as an early sign of intracardiac myxoma?
We report on a woman with previously unknown left atrial myxoma, who underwent percutaneous coronary intervention. 45 months after the initial coronary angiography, echocardiography demonstrated a large atrial myxoma, which was not seen echocardiographically before. The retrospective analysis of the pre-intervention coronary angiography revealed atypical vessels in the atrial septum, which are interpreted as early signs of myxoma
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