391 research outputs found
Filtered deterministic waves and analysis of the fractal dimension of the components of the wind velocity
The difficulty in developing models for waves in turbulent flows is a key problem in the analysis of the complexity of turbulence. We present a method to find and filter perturbations that are generated by the flow of deterministic waves from the power spectrum in the atmospheric boundary layer (ABL). The perturbation model proposed assumes that the amplitude and frequency of such waves decay with time exponentially. For illustrative purposes, we apply the technique to three time series of wind velocities obtained with a sonic anemometer. This analytical procedure allows us to filter waves of the proposed structure with a 99% significance level in the power spectrum. We have applied the same method to 540 such wind series, all painting similar results. We then compare the fractal dimension of the original series to those from which the waves have been removed. We find that the fractal dimension of the filtered waves is slightly less than that of the original series. Finally, we consider the fractal dimension of the studied series as a function of the
length-scales and dissipation rate of kinetic energy per unit mass. Our results suggest an increase of fractal dimension with both length-scale and dissipation rate of kinetic energy
Use of Annual Phosphorus Loss Estimator (APLE) Model to Evaluate a Phosphorus Index
The Phosphorus (P) Index was developed to provide a relative ranking of agricultural fields according to their potential for P loss to surface water. Recent efforts have focused on updating and evaluating P Indices against measured or modeled P loss data to ensure agreement in magnitude and direction. Following a recently published method, we modified the Maryland P Site Index (MD-PSI) from a multiplicative to a component index structure and evaluated the MD-PSI outputs against P loss data estimated by the Annual P Loss Estimator (APLE) model, a validated, field-scale, annual P loss model. We created a theoretical dataset of fields to represent Maryland conditions and scenarios and created an empirical dataset of soil samples and management characteristics from across the state. Through the evaluation process, we modified a number of variables within the MD-PSI and calculated weighting coefficients for each P loss component. We have demonstrated that our methods can be used to modify a P Index and increase correlation between P Index output and modeled P loss data. The methods presented here can be easily applied in other states where there is motivation to update an existing P Index
A double-blind, placebo-controlled, phase II, randomized study of lovastatin therapy in the treatment of mildly active rheumatoid arthritis
© 2019 The Author(s) 2019. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. 3-hydroxy-3-methylglutaryl coenzyme-A (HMG Co-A) reductase inhibitors (statins) are standard treatment for hyperlipidaemia. In addition to lipid-lowering abilities, statins exhibit multiple anti-inflammatory effects. The objectives of this study were to determine whether treatment of patients with RA with lovastatin decreased CRP or reduced disease activity. Methods: We conducted a randomized double-blind placebo-controlled 12 week trial of lovastatin vs placebo in 64 RA patients with mild clinical disease activity but an elevated CRP. The primary efficacy end point was the reduction in mean log CRP. Secondary end points included disease activity, RF and anti-CCP antibody titres. Mechanistic end points included levels of serum cytokines. Safety was assessed; hepatic and muscle toxicities were of particular interest. Results: Baseline features were similar between groups. No significant difference in mean log CRP reduction between the two groups was observed, and disease activity did not change from baseline in either treatment group. Mechanistic analyses did not reveal significant changes in any biomarkers. A post hoc analysis of subjects not using biologic therapy demonstrated a significantly greater proportion achieving ≥20% reduction in CRP from baseline in the lovastatin group compared with placebo (P-value = 0.007). No difference was observed in subjects receiving biologics. Lovastatin was well tolerated with no serious safety concerns. Conclusion: This study showed no anti-inflammatory or clinical effects on RA disease activity after 12 weeks of treatment with lovastatin. Lovastatin had a modest effect on CRP in subjects not using biologics, suggesting statins may be anti-inflammatory in selected patients. Trial registration: ClinicalTrials.gov, http://clinicaltrials.gov, NCT00302952
Measuring wearing time of knee-ankle-foot orthoses in children with cerebral palsy: comparison of parent-report and objective measurement
Purpose State Orthotic wearing time may be an important confounder in efficacy studies of treatment in children with spastic cerebral palsy (SCP). Most studies measure parent-reported wearing time with questionnaires, but it is questionable whether this yields valid results. This study aims to compare parent-reported wearing time (WTparent) with objectively measured wearing time (WTobj) in children
with SCP receiving orthotic treatment.
Method Eight children with SCP participated in this observational study. For one year, they received knee-ankle-foot orthosis (KAFO) treatment. WTparent was measured using questionnaires. WTobj was measured using temperature sensor-data-loggers that were attached to the KAFOs. The 2.5th and 97.5th percentiles and median of differences between methods (per participant) were used to calculate limits
of agreement and systematic differences.
Results There was no systematic difference between WTparent and WTobj (0.1 hours per week), but high inter-individual variation of the difference was found, as reflected by large limits of agreement (lower limit/2.5th percentile: -1.7. hours/week; upper limit/97.5th percentile: 11.1 hours/week). Conclusions Parent-reported wearing time of a knee-ankle-foot orthosis differs largely from objectively measured wearing time using temperature sensors. Therefore, parent-reported wearing time of KAFOs should be interpreted with utmost care
Development and Validation of a Smartphone-based Contrast Sensitivity Test.
PURPOSE: Contrast sensitivity (CS) testing is an important measure of visual function reflecting variations in everyday visual experience in different conditions and helps to identify more subtle vision loss. However, it is only infrequently used. To make this more accessible, we have developed and validated a smartphone-based CS test. METHODS: A new tumbling-E smartphone-based CS test was developed, Peek Contrast Sensitivity (PeekCS). This was field tested and refined through several iterations. Reference standard was a tumbling-E Pelli-Robson CS test (PRCS). The validation study was conducted in community clinics in Ethiopia. Test-retest variability was measured for both PRCS and PeekCS. PRCS and PeekCS were then compared. Correlation coefficients and 95% confidence intervals (CIs) were calculated; 95% limits of agreement were calculated and displayed on Bland-Altman plots. RESULTS: PeekCS showed strong repeatability (correlation coefficient: 0.93; 95% CI: 0.91-0.95), which was comparable with PRCS (correlation coefficient: 0.96; 95% CI: 0.95-0.97). The 95% limit of agreement for test-retest variability of PRCS and PeekCS were -0.20 to 0.21 and -0.31 to 0.29, respectively. PRCS and PeekCS were highly correlated: 0.94 (95% CI: 0.93-0.95); 95% limits of agreement -0.27 to 0.29; and mean difference 0.010 (95% CI: -0.001 to 0.022). PeekCS had a faster testing time (44.6 seconds) than PRCS (48.6 seconds): mean difference -3.98 (95% CI: -5.38 to -2.58); P < 0.001. CONCLUSIONS: The smartphone-based PeekCS is a repeatable and rapid test, providing results that are highly comparable with the commonly used PRCS test. TRANSLATIONAL RELEVANCE: PeekCS provides an accessible and easy to perform alternative for CS testing, particularly in the community setting
Development and Validation of a Digital (Peek) Near Visual Acuity Test for Clinical Practice, Community-Based Survey, and Research
PURPOSE: Unaddressed near vision impairment (NVI) affects more than 500 million people. Testing near vision is necessary to identify those in need of services. To make such testing readily accessible, we have developed and validated a new smartphone-based near visual acuity (NVA) test: Peek Near Vision (PeekNV). METHODS: Two forms of the PeekNV test were developed: (1) quantitative measurement of NVA, and (2) binary screening test for presence or absence of NVI. The validity study was carried out with 483 participants in Sagarmatha Choudhary Eye Hospital, Lahan, Nepal, using a conventional Tumbling "E" Near Point Vision Chart as the reference standard. Bland-Altman limits of agreement (LoA) were used to evaluate test agreement and test-retest repeatability. NVI screening was assessed using Cohen's kappa coefficient, sensitivity, and specificity. RESULTS: The mean difference between PeekNV and chart NVA results was 0.008 logMAR units (95% confidence interval [CI], -0.005 to 0.021) in right eye data, and the 95% LoA between PeekNV and chart testing were within 0.235 and -0.218 logMAR. As a NVI screening tool, the overall agreement between tests was 92.9% (κ = 0.85). The positive predictive value of PeekNV was 93.2% (95% CI, 89.6% to 96.9%), and the negative predictive value 92.7% (95% CI, 88.9% to 96.4%). PeekNV had a faster NVI screening time (11.6 seconds; 95% CI, 10.5 to 12.6) than the chart (14.9 seconds; 95% CI, 13.5 to 16.2; P < 0.001). CONCLUSIONS: The PeekNV smartphone-based test produces rapid NVA test results, comparable to those of an accepted NV test. TRANSLATIONAL RELEVANCE: PeekNV is a validated, reliable option for NV testing for use with smartphones or digital devices
Avoiding or Reversing Hartmann’s Procedure Provides Improved Quality of Life After Perforated Diverticulitis
# 2010 The Author(s). This article is published with open access at Springerlink.com Introduction The existing literature regarding acute perforated diverticulitis only reports about short-term outcome; longterm following outcomes have not been assessed before. The aim of this study was to assess long-term quality of life (QOL) after emergency surgery for perforated diverticulitis. Patients and Methods Validated QOL questionnaires (EQ-VAS, EQ-5D index, QLQ-C30, and QLQ-CR38) were sent to all eligible patients who had undergone emergency surgery for perforated diverticulitis in five teaching hospitals between 199
Are Elevated Levels of IGF-1 Caused by Coronary Arteriesoclerosis?: Molecular and Clinical Analysis
The importance of insulin-like growth factor-1 (IGF-1) in coronary artery disease (CAD) due to wide range of its biological effects and its therapeutic potential, has already been described. Our aim was to evaluate possible influence of IGF-1 serum level changes on coronary atherosclerosis. In case of existence of such association our further aim was to verify and explain this phenomenon by examination of promoter P1 of IGF-1gene and receptor gene for IGF-1. The study was performed in 101 consecutive patients undergo for routine coronary angiography. Quantitative and qualitative assessment of coronary atherosclerosis was performed respectively by estimation of the number of culprit lesions in coronary arteries and by Gensini score calculation. IGF-1, IGFBP3 and plasma lipoproteins were measured in all patients. In addition, we evaluated DNA from 101 patients, isolated from blood cells, which was amplified by using PCR with sophisticated primers for P1 promoter of IGF-1 gene and IGF-1 receptor gene, then analyzed utilizing SSCP technique and automatically sequenced. We observed significant increase of serum IGF-1 levels in patients with “3 vessel disease” and with high score in Gensini scale when compared to those without any narrowing lesions in coronary arteries and 0 Gensini score (in group with 3 vessel disease 215.0 ± 71.3 versuss 176.7 ± 34.2 ng/ml p = 0.04 and with high Gensini score 231.4 ± 59.3 versus 181.0 ± 37.8 ng/ml p = 0.01).We found different genotypes for five P1 promoter polymorphisms of IGF-1 gene (RS35767, RS5742612, RS228837, RS11829693, RS17879774). There were no significant associations between the observed single nucleotide polymorphism (SNP) and coronary atherosclerosis nor with levels of circulating IGF-1. We found no structural polymorphism in receptor gene for IGF-1 nor in its extracellular domain(exon 2–4) nor in internal domain (exon 16–21). The effect of increased IGF-1 serum level in our study was probably independent from structural polymorphism in promoter P1 for IGF-1 or in receptor gene for IGF-1
Temporal Structures in Positron Spectra and Charge-Sign Effects in Galactic Cosmic Rays
We present the precision measurements of 11 years of daily cosmic positron fluxes in the rigidity range from 1.00 to 41.9 GV based on 3.4 ×106 positrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The positron fluxes show distinctly different time variations from the electron fluxes at short and long timescales. A hysteresis between the electron fluxes and the positron fluxes is observed with a significance greater than 5 σ at rigidities below 8.5 GV. On the contrary, the positron fluxes and the proton fluxes show similar time variation. Remarkably, we found that positron fluxes are modulated more than proton fluxes with a significance greater than 5 σ for rigidities below 7 GV. These continuous daily positron fluxes, together with AMS daily electron, proton, and helium fluxes over an 11-year solar cycle, provide unique input to the understanding of both the charge-sign and mass dependencies of cosmic rays in the heliosphere
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