1,593 research outputs found
Coded aperture compressive temporal imaging.
We use mechanical translation of a coded aperture for code division multiple access compression of video. We discuss the compressed video's temporal resolution and present experimental results for reconstructions of > 10 frames of temporal data per coded snapshot
Dealing with missing standard deviation and mean values in meta-analysis of continuous outcomes: a systematic review
Background: Rigorous, informative meta-analyses rely on availability of appropriate summary statistics or individual
participant data. For continuous outcomes, especially those with naturally skewed distributions, summary
information on the mean or variability often goes unreported. While full reporting of original trial data is the ideal,
we sought to identify methods for handling unreported mean or variability summary statistics in meta-analysis.
Methods: We undertook two systematic literature reviews to identify methodological approaches used to deal with
missing mean or variability summary statistics. Five electronic databases were searched, in addition to the Cochrane
Colloquium abstract books and the Cochrane Statistics Methods Group mailing list archive. We also conducted cited
reference searching and emailed topic experts to identify recent methodological developments. Details recorded
included the description of the method, the information required to implement the method, any underlying
assumptions and whether the method could be readily applied in standard statistical software. We provided a
summary description of the methods identified, illustrating selected methods in example meta-analysis scenarios.
Results: For missing standard deviations (SDs), following screening of 503 articles, fifteen methods were identified in
addition to those reported in a previous review. These included Bayesian hierarchical modelling at the meta-analysis
level; summary statistic level imputation based on observed SD values from other trials in the meta-analysis; a practical
approximation based on the range; and algebraic estimation of the SD based on other summary statistics. Following
screening of 1124 articles for methods estimating the mean, one approximate Bayesian computation approach and
three papers based on alternative summary statistics were identified. Illustrative meta-analyses showed that when
replacing a missing SD the approximation using the range minimised loss of precision and generally performed better
than omitting trials. When estimating missing means, a formula using the median, lower quartile and upper quartile
performed best in preserving the precision of the meta-analysis findings, although in some scenarios, omitting trials
gave superior results.
Conclusions: Methods based on summary statistics (minimum, maximum, lower quartile, upper quartile, median)
reported in the literature facilitate more comprehensive inclusion of randomised controlled trials with missing mean or
variability summary statistics within meta-analyses
Multiorgan impairment in low-risk individuals with post-COVID-19 syndrome: a prospective, community-based study
OBJECTIVE: To assess medium-term organ impairment in symptomatic individuals following recovery from acute SARS-CoV-2 infection. DESIGN: Baseline findings from a prospective, observational cohort study. SETTING: Community-based individuals from two UK centres between 1 April and 14 September 2020. PARTICIPANTS: Individuals â„18 years with persistent symptoms following recovery from acute SARS-CoV-2 infection and age-matched healthy controls. INTERVENTION: Assessment of symptoms by standardised questionnaires (EQ-5D-5L, Dyspnoea-12) and organ-specific metrics by biochemical assessment and quantitative MRI. MAIN OUTCOME MEASURES: Severe post-COVID-19 syndrome defined as ongoing respiratory symptoms and/or moderate functional impairment in activities of daily living; single-organ and multiorgan impairment (heart, lungs, kidneys, liver, pancreas, spleen) by consensus definitions at baseline investigation. RESULTS: 201 individuals (mean age 45, range 21-71 years, 71% female, 88% white, 32% healthcare workers) completed the baseline assessment (median of 141 days following SARS-CoV-2 infection, IQR 110-162). The study population was at low risk of COVID-19 mortality (obesity 20%, hypertension 7%, type 2 diabetes 2%, heart disease 5%), with only 19% hospitalised with COVID-19. 42% of individuals had 10 or more symptoms and 60% had severe post-COVID-19 syndrome. Fatigue (98%), muscle aches (87%), breathlessness (88%) and headaches (83%) were most frequently reported. Mild organ impairment was present in the heart (26%), lungs (11%), kidneys (4%), liver (28%), pancreas (40%) and spleen (4%), with single-organ and multiorgan impairment in 70% and 29%, respectively. Hospitalisation was associated with older age (p=0.001), non-white ethnicity (p=0.016), increased liver volume (p<0.0001), pancreatic inflammation (p<0.01), and fat accumulation in the liver (p<0.05) and pancreas (p<0.01). Severe post-COVID-19 syndrome was associated with radiological evidence of cardiac damage (myocarditis) (p<0.05). CONCLUSIONS: In individuals at low risk of COVID-19 mortality with ongoing symptoms, 70% have impairment in one or more organs 4âmonths after initial COVID-19 symptoms, with implications for healthcare and public health, which have assumed low risk in young people with no comorbidities. TRIAL REGISTRATION NUMBER: NCT04369807; Pre-results
Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes
Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei
A randomised, open label, active comparator trial assessing the effects of 26âweeks of liraglutide or sitagliptin on cardiovascular function in young obese adults with type 2 diabetes
Aim
To compare the effects of a glucagonâlike peptideâ1 receptor agonist and a dipeptidyl peptidaseâ4 inhibitor on magnetic resonance imagingâderived measures of cardiovascular function.
Materials and methods
In a prospective, randomized, openâlabel, blinded endpoint trial liraglutide (1.8 mg) and sitagliptin (100âmg) were compared in asymptomatic, nonâinsulin treated young (aged 18â50âyears) adults with obesity and type 2 diabetes. The primary outcome was difference in circumferential peak early diastolic strain rate change (PEDSR), a biomarker of cardiac diastolic dysfunction 26âweeks after randomization. Secondary outcomes included other indices of cardiac structure and function, HbA1c and body weight.
Results
Seventyâsix participants were randomized (54% female, meanâ±âSD age 44â± 6âyears, diabetes duration 4.4âyears, body mass index 35.3â±â6.1 kgâmâ2), of whom 65% had â„1 cardiovascular risk factor. Sixtyâone participants had primary outcome data available. There were no statistically significant betweenâgroup differences (intentionâtoâtreat; mean [95% confidence interval]) in PEDSR change (â0.01 [â0.07, +0.06] sâ1), left ventricular ejection fraction (â1.98 [â4.90, +0.94]%), left ventricular mass (+1.14 [â5.23, +7.50] g) or aortic distensibility (â0.35 [â0.98, +0.28] mmHgâ1âĂâ10â3) after 26âweeks. Reductions in HbA1c (â4.57 [â9.10, â0.37] mmolâmolâ1) and body weight (â3.88 [â5.74, â2.01] kg) were greater with liraglutide.
Conclusion
There were no differences in cardiovascular structure or function after shortâterm use of liraglutide and sitagliptin in younger adults with obesity and type 2 diabetes. Longer studies in patients with more severe cardiac dysfunction may be necessary before definitive conclusions can be made about putative pleiotropic properties of incretinâbased therapies
Poor glycaemic control and ectopic fat deposition mediates the increased risk of non-alcoholic steatohepatitis in high-risk populations with type 2 diabetes: Insights from Bayesian-network modelling.
BackgroundAn estimated 55.5% and 37.3% of people globally with type 2 diabetes (T2D) will have concomitant non-alcoholic fatty liver disease (NAFLD) and the more severe fibroinflammatory stage, non-alcoholic steatohepatitis (NASH). NAFLD and NASH prevalence is projected to increase exponentially over the next 20 years. Bayesian Networks (BNs) offer a powerful tool for modelling uncertainty and visualising complex systems to provide important mechanistic insight.MethodsWe applied BN modelling and probabilistic reasoning to explore the probability of NASH in two extensively phenotyped clinical cohorts: 1) 211 participants with T2D pooled from the MODIFY study & UK Biobank (UKBB) online resource; and 2) 135 participants without T2D from the UKBB. MRI-derived measures of visceral (VAT), subcutaneous (SAT), skeletal muscle (SMI), liver fat (MRI-PDFF), liver fibroinflammatory change (liver cT1) and pancreatic fat (MRI-PDFF) were combined with plasma biomarkers for network construction. NASH was defined according to liver PDFF >5.6% and liver cT1 >800ms. Conditional probability queries were performed to estimate the probability of NASH after fixing the value of specific network variables.ResultsIn the T2D cohort we observed a stepwise increase in the probability of NASH with each obesity classification (normal weight: 13%, overweight: 23%, obese: 36%, severe obesity: 62%). In the T2D and non-T2D cohorts, elevated (vs. normal) VAT conferred a 20% and 1% increase in the probability of NASH, respectively, while elevated SAT caused a 7% increase in NASH risk within the T2D cohort only. In those with T2D, reducing HbA1c from the 'high' to 'low' value reduced the probability of NASH by 22%.ConclusionUsing BNs and probabilistic reasoning to study the probability of NASH, we highlighted the relative contribution of obesity, ectopic fat (VAT and liver) and glycaemic status to increased NASH risk, namely in people with T2D. Such modelling can provide insights into the efficacy and magnitude of public health and pharmacological interventions to reduce the societal burden of NASH
Effects of Low-Energy Diet or Exercise on Cardiovascular Function in Working-Age Adults With Type 2 Diabetes: A Prospective, Randomized, Open-Label, Blinded End Point Trial
OBJECTIVE To confirm the presence of subclinical cardiovascular dysfunction in working-age adults with type 2 diabetes (T2D) and determine whether this is improved by a low-energy meal replacement diet (MRP) or exercise training.
RESEARCH DESIGN AND METHODS This article reports on a prospective, randomized, open-label, blinded end point trial with nested case-control study. Asymptomatic younger adults with T2D were randomized 1:1:1 to a 12-week intervention of 1) routine care, 2) supervised aerobic exercise training, or 3) a low-energy (âŒ810 kcal/day) MRP. Participants underwent echocardiography, cardiopulmonary exercise testing, and cardiac magnetic resonance (CMR) at baseline and 12 weeks. The primary outcome was change in left ventricular (LV) peak early diastolic strain rate (PEDSR) as measured by CMR. Healthy volunteers were enrolled for baseline case-control comparison.
RESULTS Eighty-seven participants with T2D (age 51 ± 7 years, HbA1c 7.3 ± 1.1%) and 36 matched control participants were included. At baseline, those with T2D had evidence of diastolic dysfunction (PEDSR 1.01 ± 0.19 vs. 1.10 ± 0.16 sâ1, P = 0.02) compared with control participants. Seventy-six participants with T2D completed the trial (30 routine care, 22 exercise, and 24 MRP). The MRP arm lost 13 kg in weight and had improved blood pressure, glycemia, LV mass/volume, and aortic stiffness. The exercise arm had negligible weight loss but increased exercise capacity. PEDSR increased in the exercise arm versus routine care (ÎČ = 0.132, P = 0.002) but did not improve with the MRP (ÎČ = 0.016, P = 0.731).
CONCLUSIONS In asymptomatic working-age adults with T2D, exercise training improved diastolic function. Despite beneficial effects of weight loss on glycemic control, concentric LV remodeling, and aortic stiffness, a low-energy MRP did not improve diastolic function
Correlation between Fischer-Tropsch catalytic activity and composition of catalysts
This paper presents the synthesis and characterization of monometallic and bimetallic cobalt and iron nanoparticles supported on alumina. The catalysts were prepared by a wet impregnation method. Samples were characterized using temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), CO-chemisorption, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM-EDX) and N2-adsorption analysis. Fischer-Tropsch synthesis (FTS) was carried out in a fixed-bed microreactor at 543 K and 1 atm, with H2/CO = 2 v/v and space velocity, SV = 12L/g.h. The physicochemical properties and the FTS activity of the bimetallic catalysts were analyzed and compared with those of monometallic cobalt and iron catalysts at similar operating conditions
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