Difference Plots Research Articles

Comparative Study of Arterial Compliance Using Invasive and Noninvasive Blood Pressure Waveform

Most of the epidemiological studies have shown a good relationship between blood pressure and manifestation of cardiovascular diseases (CVD). CVD has become a very common health condition that exhibits significant changes in distensibilility, compliance, and elastic modulus of the arterial vascular system. The main causes of this disease are the spreading of fats and cholesterols which initiate the damaging of endothelium, decreasing wall buffering capacity, and hardening of the arteries eventually leading to severe narrowing. We compared data from invasive and non-invasive blood pressure wave form. Using the Windkessel model, to estimate the arterial compliance as vascular index, we used data after the aortic valve closed to the end-diastolic point of blood pressure waveforms, utilized Bland-Altman difference plot, T-test, box whisker plot and scatter diagram. We analyzed physiological real data and investigated the correlation between the non-invasive and invasive blood pressure wave form. Non-invasive compressive pulse waveforms can be used to assess the total compliance of the arterial blood pressure waveforms of the invasive aorta that indicates the buffering of muscle and adipose tissue.

CarbonXS GUI: a graphical front-end for CarbonXS

The crystallographic structure of disordered carbons impacts their performance in components for fuel cells, batteries and catalyst supports. Obtaining parameters such as lattice constants and crystal domain size requires an appropriate model for these carbons, a task accomplished with the Fortran program CarbonXS published in 1993. CarbonXS GUI contains an updated version of CarbonXS and a graphical user interface wrapper. This new version provides a graphical method of configuring and operating CarbonXS, a calculation mode to simulate diffraction patterns, and immediate feedback in the form of fit–source and difference plots. CarbonXS GUI is available for free on Windows, Linux and Mac OSX at http://github.com/lktsui/carbon_xs_gui.

Agreement between manual relaxometry and semi-automated scanner-based multi-echo Dixon technique for measuring liver T2* in a pediatric and young adult population.

Commercially available 3D multi-echo Dixon (mDixon) sequences provide parametric maps of liver T2*, obviating manual curve fitting that is often required with conventional gradient recalled echo (GRE)-based multi-echo relaxometry, potentially simplifying clinical work flow. The purpose of our study was to compare T2* values generated by a 3D mDixon sequence to values generated by GRE-based T2* relaxometry with manual curve fitting in a pediatric and young adult population. We reviewed clinical MRI exams performed at 1.5T for liver iron content estimation between February 2015 and June 2016 that included both mDixon and multi-echo GRE pulse sequences. We obtained mean T2* measurements based on each sequence by drawing regions of interest on each of four axial slices through the mid-liver. We compared mDixon-based and GRE-based T2* measurements using paired t-tests and assessed agreement using single-measure intra-class correlation coefficients and Bland-Altman difference plots. One hundred nine patients met inclusion criteria (site 1=82; site 2=27). Mean age was 12.4±5.8years, and 42 subjects (39%) were female. There was no statistically significant difference in mean T2* values for the two sequences (pooled means: 11.7±11.0 [GRE] vs. 11.7±10.9ms [mDixon]; P=0.93). There was excellent absolute agreement between sequences (intraclass correlation coefficient [ICC]=0.98 for patients at both sites, confidence interval [CI]: 0.97-0.98 with mean bias of 0.0ms [-4.2ms to +4.2ms]). 3D mDixon is accurate for measuring liver T2* and can likely replace 2D GRE-based relaxometry.

Validation of multi-frequency bioelectrical impedance analysis versus dual-energy X-ray absorptiometry to measure body fat percentage in overweight/obese Colombian adults.

To verify the validity of multi-frequency bioelectrical impedance analysis (mBCA) for predicting body fat percentage (BF%) in overweight/obese adults using dual-energy X-ray absorptiometry (DXA) as the reference method. Forty-eight adults participated (54% women, mean age = 41.0 ± 7.3 years old). The Pearson's correlation coefficient was used to evaluate the correlation between BIA and BF% assessed by DXA. The concordance between BF% measured by both methods was obtained with Lin's concordance correlation coefficient and Bland-Altman difference plots. Measures of BF% were estimated as 39.0 (SD = 6.1) and 38.3 (SD = 6.5) using DXA and mBCA, respectively. The Pearson's correlation coefficient reflected a strong correlation (r =.921, P = .001). The paired t-test showed a significant mean difference between these methods for obese men BF% of -0.6 [(SD 1.95; 95% CI = -4.0 to 3.0), P =.037]. Overall, the bias of the mBCA was -0.6 [(SD 2.2; 95% CI = -5.0 to 3.7), P =.041], which indicated that the mBCA method significantly underestimated BF% in comparison to the reference method. Finally, in both genders, Lin's concordance correlation coefficient showed a strong agreement. More specifically the DXA value was ρc = 0.943 (95% CI = 0.775 to 0.950) and the mBCA value was ρc = 0.948 (95% CI = 0.778 to 0.978). Our analysis showed a strong agreement between the two methods as reflected in the range of BF%. These results show that mBCA and DXA are comparable methods for measuring body composition with higher body fat percentages. However, due to broad limits of agreement, we can only recommend mBCA for groups of populations.

LB.01.08] VALIDATION OF THE SUNTECH® CT40™ BLOOD PRESSURE MEASUREMENT DEVICE BY THE BHS PROTOCOL AND THE AAMI/ISO 8160-2

Objective: To perform a simultaneous, independent validation of the oscillometric CT40 device for BP measurement, produced by SunTech®, according to the 1993 protocol of the British Hypertension Society (BHS) and the standard of the Association for the Advancement of Medical Instrumentation (AAMI)/the International Organization for Standardization (ISO) 8160-2:2013.Design and method: Study participants were aged > 18 years old and written informed consent was obtained from each subject. The study was approved by the institutional review board. Subjects recruitment conditions (sex, arm circumference, BP readings) as long as procedures and data analysis fulfilled the requirements stated by BHS protocol and AAMI/ISO8160-2:2013 standard. Results: A total of 94 participants were included, 52 females (55.3%), mean age (years ± SD) 63.1 ± 18.0, mean arm circumference (cm ± SD) 35.0 ± 9.0. The average of observers entry BPs were 146.9 ± 37.2 mmHg for systolic (SBP) and 82.2 ± 22.1 mmHg for diastolic BP (DBP), Table 1. As for the BHS protocol, differences between standard measurement and test device within 5, 10, and 15 mmHg, for the better observer (A), were 79.4, 95.4 and 100.0%, respectively for SBP, and 82.6, 97.2 and 100.0% for DBP, Table 2. Figures in the low, medium and high pressure ranges are shown in Table 3. Scatter plots of differences between the test device and the better observer (A) against the average of the device and observer pressure values are shown for SBP (Figure 1) and DBP (Figure 2). The mean difference between the readings obtained by using the test device and those obtained by the observers (AAMI/ISO8160-2:2013 standard criteria 1) were 0.3 ± 5.0 mmHg (SBP) and −0.8 ± 4.3 mmHg (DBP), and the mean differences between the average of three readings of the test device and the average of the observers, for each participant (criteria 2), were 0.3 ± 3.9 and −0.8 ± 3.5 mmHg for SBP and DBP, respectively. Conclusions: The CT 40 blood pressure device achieved A/A grade of the BHS protocol and fulfilled the requirements (criteria 1 and 2) of the AAMI/ISO standard. CT 40 can be recommended for BP measurement in adults.

Structural phase transition, electronic and superconducting properties of ScBi and YBi

The structural, electronic, lattice dynamic and superconducting properties of ScBi and YBi compounds are investigated using density functional theory. The calculated values of structural phase transition pressure from NaCl-type (B1) to CsCl-type (B2) phase and ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B׳) are compared with the available theoretical data. The electronic and bonding properties are discussed in terms of band structure, density of states and charge density difference plots. The phonon dispersion curves and phonon density of states are also discussed for both the compounds and calculated for the first time for ScBi compound. The phonon frequencies are positive at ambient and high pressure throughout the Brillouin zone in rock-salt structure revealing the stability in that phase. Eliashberg spectral function, electron-phonon coupling constant and superconducting transition temperature of ScBi and YBi are discussed in detail. The values of Tc are 0.97K for ScBi and 1.29K for YBi at ambient pressure.

An interactive website for analytical method comparison and bias estimation

ObjectivesRegulatory standards mandate laboratories to perform studies to ensure accuracy and reliability of their test results. Method comparison and bias estimation are important components of these studies. Design & methodsWe developed an interactive website for evaluating the relative performance of two analytical methods using R programming language tools. The website can be accessed at https://bahar.shinyapps.io/method_compare/. ResultsThe site has an easy-to-use interface that allows both copy-pasting and manual entry of data. It also allows selection of a regression model and creation of regression and difference plots. Available regression models include Ordinary Least Squares, Weighted-Ordinary Least Squares, Deming, Weighted-Deming, Passing-Bablok and Passing-Bablok for large datasets. The server processes the data and generates downloadable reports in PDF or HTML format. ConclusionsOur website provides clinical laboratories a practical way to assess the relative performance of two analytical methods.

Accuracy and consistency of anti‐Xa activity measurement for determination of rivaroxaban plasma levels

Background Determining the plasma level of direct oral anticoagulants reliably is important in the work-up of complex clinical situations. Objectives To study the accuracy and consistency of anti-Xa assays for rivaroxaban plasma concentration in a prospective, multicenter evaluation study employing different reagents and analytical platforms. Methods Rivaroxaban 20mg was administered once daily to 20 healthy volunteers and blood samples were taken at peak and trough levels (clinicaltrials.gov NCT01710267). Anti-Xa activity was determined in 10 major laboratories using different reagents and analyzers; corresponding rivaroxaban plasma concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). Findings Overall Pearson's correlation coefficient of anti-Xa levels and HPLC-MS results was 0.99 for Biophen® Heparin (95% CI, 0.99, 0.99), Biophen® DiXaI (95% CI, 0.99, 0.99) and STA® anti-Xa liquid (95% CI, 0.99, 1.00). Correlation was lower in rivaroxaban concentrations below 50μgL-1 and above 200μgL-1 . The overall bias of the Bland-Altman difference plot was 14.7μgL-1 for Biophen Heparin, 17.9μgL-1 for Biophen DiXal and 19.0μgL-1 for STA anti-Xa liquid. Agreement between laboratories was high at peak level but limited at trough level. Conclusions Anti-Xa activity correlated well with rivaroxaban plasma concentrations, especially in a range between 50 and 200μgL-1 . However, anti-Xa assays systematically overestimated rivaroxaban concentration as compared with HPLC-MS, particularly at higher concentrations. This overestimation, coupled with an apparent interindividual variation, might affect the interpretation of results in some situations.

Insight into π-hole interactions containing the inorganic heterocyclic compounds S2N2/SN2P2.

Similar to σ-hole interactions, the π-hole interaction has attracted much attention in recent years. According to the positive electrostatic potentials above and below the surface of inorganic heterocyclic compounds S2N2 and three SN2P2 isomers (heterocyclic compounds 1-4), and the negative electrostatic potential outside the X atom of XH3 (X=N, P, As), S2N2/SN2P2⋯XH3 (X=N, P, As) complexes were constructed and optimized at the MP2/aug-cc-pVTZ level. The X atom of XH3 (X=N, P, As) is almost perpendicular to the ring of the heterocyclic compounds. The π-hole interaction energy becomes greater as the trend goes from 1⋯XH3 to 4⋯XH3. These π-hole interactions are weak and belong to "closed-shell" noncovalent interactions. According to the energy decomposition analysis, of the three attractive terms, the dispersion energy contributes more than the electrostatic energy. The polarization effect also plays an important role in the formation of π-hole complexes, with the contrasting phenomena of decreasing electronic density in the π-hole region and increasing electric density outside the X atom of XH3 (X=N, P, As). Graphical abstract Computed density difference plots for the complexes 3⋯NH 3 (a 1), 3⋯PH 3 (b 1), 3⋯AsH 3 (c 1) and electron density shifts for the complexes 3⋯NH 3 (a 2), 3⋯PH 3 (b 2),3⋯AsH 3 (c 2) on the 0.001 a.u. contour.

An Emotion Recognition Approach based on Wavelet Transform and Second-Order Difference Plot of ECG

Emotion, as a psychophysiological state, plays an important role in human communications and daily life. Emotion studies related to the physiological signals are recently the subject of many researches. In This study a hybrid feature based approach was proposed to examine affective states. To this effect, Electrocardiogram (ECG) signals of 47 students were recorded using pictorial emotion elicitation paradigm. Affective pictures were selected from the International Affective Picture System and assigned into four different emotion classes. After extracting approximate and detail coefficients of Wavelet Transform (WT / Daubechies 4 at level 8), two measures of the second-order difference plot (CTM and D) were calculated for each wavelet coefficient. Subsequently, Least Squares Support Vector Machine (LS-SVM) was applied to discriminate between affective states and the rest. The statistical analysis indicated that the density of CTM in the rest is distinctive from the emotional categories. In addition, the second-order difference plot measurements at the last level of WT coefficients showed significant differences between the rest and emotion categories. Applying LS-SVM, the maximum classification rate of 80.24 % was reached for discrimination between rest and fear. The results of this study indicate the usefulness of the WT in combination with nonlinear technique in characterizing emotional states.

Ionization of pyridine: Interplay of orbital relaxation and electron correlation.

The valence shell ionization spectrum of pyridine was studied using the third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green's function and the outer-valence Green's function method. The results were used to interpret angle resolved photoelectron spectra recorded with synchrotron radiation in the photon energy range of 17-120 eV. The lowest four states of the pyridine radical cation, namely, 2A2(1a2-1), 2A1(7a1-1), 2B1(2b1-1), and 2B2(5b2-1), were studied in detail using various high-level electronic structure calculation methods. The vertical ionization energies were established using the equation-of-motion coupled-cluster approach with single, double, and triple excitations (EOM-IP-CCSDT) and the complete basis set extrapolation technique. Further interpretation of the electronic structure results was accomplished using Dyson orbitals, electron density difference plots, and a second-order perturbation theory treatment for the relaxation energy. Strong orbital relaxation and electron correlation effects were shown to accompany ionization of the 7a1 orbital, which formally represents the nonbonding σ-type nitrogen lone-pair (nσ) orbital. The theoretical work establishes the important roles of the π-system (π-π* excitations) in the screening of the nσ-hole and of the relaxation of the molecular orbitals in the formation of the 7a1(nσ)-1 state. Equilibrium geometric parameters were computed using the MP2 (second-order Møller-Plesset perturbation theory) and CCSD methods, and the harmonic vibrational frequencies were obtained at the MP2 level of theory for the lowest three cation states. The results were used to estimate the adiabatic 0-0 ionization energies, which were then compared to the available experimental and theoretical data. Photoelectron anisotropy parameters and photoionization partial cross sections, derived from the experimental spectra, were compared to predictions obtained with the continuum multiple scattering approach.

Comparison of a full-spectrum multi-analyte clinical analyser with six reference instruments using canine and feline blood samples

In this study, we report the characterisation of a novel centrifugation and spectrum-integrated veterinary clinical analyser, the AmiShield<sup>TM</sup>, which has been developed for the multiplex measurement of biochemical, electrolyte and immunoassay parameters in a point-of-care testing environment. The aims of this study were to evaluate the analytical performance of the AmiShield<sup>TM</sup> and to compare it with six reference instruments using clinical blood samples. Two hundred and four canine and 120 feline blood samples collected from veterinary teaching hospitals were analysed in parallel using the AmiShield and appropriate reference instruments. All results were evaluated separately for canine and feline specimens. The instrument’s analytical performance was evaluated initially for short- and long-term precision, bias, and observed total error using quality control material. This was followed by comparison of clinical specimens on the AmiShield analyser in parallel with the Vitros and Hitachi for biochemical parameters, VetScan and SNAPshot for total bile acids, and VetLyte and Biolyte for electrolytes. Overall, the AmiShield analyser’s performance met the standards of the American Society for Veterinary Clinical Pathology for total allowable error for most analytes, and can be considered suitable for use in veterinary clinical practices. Using canine samples, excellent correlation coefficients (r ≧ 0.92) were identified for 14 analytes of various categories including glucose, total protein, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, amylase, blood urea nitrogen, creatinine, phosphorus, Na<sup>+</sup>, K<sup>+</sup>, Cl<sup>–</sup> and total bile acid, while good correlations (0.91 ≧ r ≧ 0.80) were recorded for albumin (r = 0.91). Bland-Altman difference plots also showed agreement (greater than 95% within Limits of Agreement) for glucose, total protein, albumin, alanine aminotransferase, alkaline phosphatase, total bilirubin, amylase, blood urea nitrogen, creatinine, Na<sup>+</sup>, K<sup>+</sup>, Cl<sup>–</sup> and total bile acid between AmiShield and the reference instruments. However, aspartate aminotransferase and phosphorus exhibited higher outliers, implying potential problems associated with matrix interferences such as lipemic samples, which warrant further study. This study demonstrates that the AmiShield compares favourably with standard reference instruments, and the new device generated data of high quality for most analytes in clinical canine and feline samples. The capability of reliably measuring multi-category analytes in one device using minute amounts (170 μl) of whole blood and short turn-around times (< 15 min) underlines the high potential of the device as a good alternative in-house diagnostic application.

Multicenter verification of the Sysmex XN-Series.

Verification of hemocytometry equipment deviates significantly from that of clinical chemistry equipment due to the absence of appropriate control material and the need for fresh material. In practice, verification is limited to comparison with the previously used equipment and determination of reproducibilities. Particularly in multicenter settings, harmonization of results is necessary. If the same equipment is used in several laboratory departments, calibration and uniformity are important issues. In this study, seven Sysmex XN hematology modules distributed over three laboratories were evaluated with the same set of samples (n=160). Results of each Sysmex XN hematology module were compared with the results of the Sysmex XE-2100 hematology analyzer using linear regression. Although excellent correlation coefficients were obtained, in many cases the criteria for slope and/or intercept were not met. Therefore, the same data were analyzed with Bland-Altman difference plots with three times the specified CV% of the parameter as limits of agreement. At least 90% of the determinations per parameter and per module must comply with those limits of agreement. Almost all parameters on each module fulfilled these criteria, and only RBC and Ht from respectively two and four XN modules had to be recalibrated. Reproducibility of each parameter was determined 10 times in patient samples with low, normal, and high levels. Reproducibility of all parameters was within the specifications of the manufacturer and the biological variability. With this straightforward method, all seven Sysmex XN hematology modules demonstrated uniform results, which were identical to those of the previously used Sysmex XE-2100 hematology analyzer, the performance of which was well known.

Abstract 502: Effect of Intensive Versus Standard Blood Pressure Control on Stroke and Serious Adverse Event: A Bivariate Analysis on the Net Clinical Benefit

Background: Intensive blood pressure (BP) control is associated with a reduced risk of stroke but a greater risk of serious adverse event (SAE), thereby offsetting the benefit-to-risk ratio of this strategy. Methods: Using a previously described method of bivariate analysis, efficacy and safety outcomes were collectively analyzed as net clinical benefit (NCB) based on data from three randomized controlled trials comparing intensive versus standard BP control among 17,115 patients (ACCORD, SPS3, and SPRINT trials). Bivariate risk difference was assessed by the minimum distance from NCB curve to 95% CI of risk difference in all-cause stroke and SAE. Results: Compared to standard BP target, intensive strategies reduced all-cause stroke by 0.70% (95% CI: 0.19% to 1.21%; P = 0.007) and increased SAE by 1.85% (95% CI: 1.35% to 2.34%; P < 0.0001). With a non-inferiority margin of 25%, standard strategy was preferable with respect to NCB in diabetics (bivariate risk difference: 1.29% [0.40% to 2.31%]) and in patients without diabetes or prior stroke (1.55% [0.76% to 2.37%]). Among patients with stroke history, intensive strategy failed to achieve non-inferiority in NCB (-0.18% [-1.01% to 0.83%]). Conclusions: Bivariate analysis is a novel method that allows simultaneous display and assessment of efficacy and safety outcomes. Among patients with cardiovascular risk factors, intensive BP control failed to demonstrate a favorable risk-benefit profile against standard BP control with respect to the tradeoff between stroke and SAE. Figure 1. Net clinical benefit of intensive vs standard BP control Figure 2. Forest plot of bivariate risk difference in stroke and SAE

Depth of anaesthesia assessment using interval second‐order difference plot and permutation entropy techniques

This study presents a new method to apply the interval second-order difference plot (ISODP) and interval permutation entropy (IPE) techniques to assess the depth of anaesthesia (DoA). First, the denoised electroencephalograph signals are decomposed into 13 different frequency bands. The second-order difference plot (SODP) and permutation entropy (PE) values of each frequency band are calculated. The SODP and PE values of high-frequency bands (21.5-47 Hz) show the highest linear relationship with the anaesthesia states, therefore they are selected to form the parameter set. Then the SODP and PE parameters are fine tuned using the interval feature technique. Finally, a new index is designed using the ISODP and IPE. The new index is evaluated and compared with measured bispectral (BIS). The results show that there is a very close correlation between the proposed index and the BIS during different anaesthetic states. The new index also shows an earlier time response (3.1–59.7 s) than BIS during the change of anaesthetic states. In addition, the proposed index is able to continuously assess the DoA of patients when the quality of signal is poor and the BIS does not have any valid outputs.

Weakly bound water structure, bond valence saturation and water dynamics at the goethite (100) surface/aqueous interface: ab initio dynamical simulations

BackgroundMany important geochemical and biogeochemical reactions occur in the mineral/formation water interface of the highly abundant mineral, goethite [α-Fe(OOH)]. Ab initio molecular dynamics (AIMD) simulations of the goethite α-FeOOH (100) surface and the structure, water bond formation and dynamics of water molecules in the mineral/aqueous interface are presented. Several exchange correlation functionals were employed (PBE96, PBE96 + Grimme, and PBE0) in the simulations of a (3 × 2) goethite surface with 65 absorbed water molecules in a 3D-periodic supercell (a = 30 Å, FeOOH slab ~12 Å thick, solvation layer ~18 Å thick).ResultsThe lowest energy goethite (100) surface termination model was determined to have an exposed surface Fe3+ that was loosely capped by a water molecule and a shared hydroxide with a neighboring surface Fe3+. The water molecules capping surface Fe3+ ions were found to be loosely bound at all DFT levels with and without Grimme corrections, indicative that each surface Fe3+ was coordinated with only five neighbors. These long bonds were supported by bond valence theory calculations, which showed that the bond valence of the surface Fe3+ was saturated and surface has a neutral charge. The polarization of the water layer adjacent to the surface was found to be small and affected only the nearest water. Analysis by density difference plots and localized Boys orbitals identified three types of water molecules: those loosely bound to the surface Fe3+, those hydrogen bonded to the surface hydroxyl, and bulk water with tetrahedral coordination. Boys orbital analysis showed that the spin down lone pair orbital of the weakly absorbed water interact more strongly with the spin up Fe3+ ion. These weakly bound surface water molecules were found to rapidly exchange with the second water layer (~0.025 exchanges/ps) using a dissociative mechanism.ConclusionsWater molecules adjacent to the surface were found to only weakly interact with the surface and as a result were readily able to exchange with the bulk water. To account for the large surface Fe–OH2 distances in the DFT calculations it was proposed that the surface Fe3+ atoms, which already have their bond valence fully satisfied with only five neighbors, are under-coordinated with respect to the bulk coordination.Graphical abstractAll first principle calculations, at all practically achievable levels, for the goethite 100 aqueous interface support a long bond and weak interaction between the exposed surface Fe3+ and water molecules capping the surface. This result is supported by bond valence theory calculations and is indicative that each surface Fe3+ is coordinated with only 5 neighbors.

DFT study of the intercalation of layered double hydroxides and layered hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate: Exfoliation and hydration properties

DFT calculations were performed for the simulation of the intercalations of Zn2Al-layered double hydroxide and Zn-layered hydroxide salts with dodecylsulfate and dodecylbenzene sulfonate. A structural and energetic analyses of the exfoliation processes were computed and compared with Perdew-Burke-Ernzerhof exchange-correlation (PBE) and Van der Waals-aware density (vdW-DF) functionals and with the semi-empirical approach DFT-D2. It could be concluded that the layers cell parameters were not affected by the applied approach. On the other hand, the basal spacing and the exfoliation energies presented variations with respect to the simulation. The influence of water molecules hydrating the polar heads of the anions intercalated in the interlayer region was also investigated. Furthermore, the interactions between the anions and the positive layers and the influence of hydration waters could be resolved by means of charge density difference plots and Bader charges. Projected density of states (PDOS) showed the possible acid and basic sites of these compounds for both dehydrated and hydrated structures.

A cross-sectional study on sarcopenia using different methods: reference values for healthy Saudi young men

BackgroundThe aim of this study was to determine reference values for sarcopenia indices using different methods in healthy Saudi young men.MethodsParticipants included 232 Saudi men aged between 20 and 35 years. The study measured anthropometric indices, blood pressure, hand grip strength, and lean muscle mass using dual-energy X-ray absorptiometry (DXA), and bioelectrical impedance analysis (BIA) was performed using Inbody 770 and Tanita 980 devices.ResultsUsing DXA, the mean value of appendicular lean mass divided by the height squared (ALM/ht2) was found to be 8.97 ± 1.23 kg/m2; hand grip strength measured 42.8 ± 7.6 kg. While the differences between DXA and BIA (Tanita) were significant for all parameters, the differences between DXA and Inbody values were significant only for ALM parameters. Inbody sensitivity and specificity values were 73% and 95.9%, respectively. The kappa (P = 0.80) and p values (P < 0.001) showed good agreement between Inbody and DXA, whereas Tanita sensitivity and specificity values were 54.2% and 98.3%, respectively. Bland-Altman plots for differences in lean mass values between Tanita, Inbody, and DXA methods showed very high bias for Tanita and DXA, with significant differences (P < 0.001).ConclusionsThe cut-off values for sarcopenia indices for Saudi young men are different from those of other ethnicities. The use of tailored cut-off reference values instead of a general cut-off for BIA devices is recommended.

Density functional theory study of defects in unalloyed δ-Pu

Using density functional theory, we explore various classical point and complex defects within the face-centered cubic unalloyed δ-plutonium matrix that are potentially induced from self-irradiation. For plutonium only defects, the most energetically stable defect is a distorted split-interstitial. Gallium, the δ-phase stabilizer, is thermodynamically stable as a substitutional defect, but becomes unstable when participating in a complex defect configuration. Complex uranium defects may thermodynamically exist as uranium substitutional with neighboring plutonium interstitial and stabilization of uranium within the lattice is shown via partial density of states and charge density difference plots to be 5f hybridization between uranium and plutonium.

Comparison of 13 Commercially Available Cardiac Troponin Assays in a Multicenter North American Study.

We examined the concordance of 13 commercial cardiac troponin (cTn) assays [point-of-care, high-sensitivity (hs), and conventional] using samples distributed across a continuum of results. cTnI (11 assays) and cTnT (2 assays) were measured in 191 samples from 128 volunteers. cTn assays included Abbott (iSTAT, STAT, and hs), Alere (Cardio 3), Beckman (AccuTnI+3), Pathfast (cTnI-II), Ortho (Vitros), Siemens (LOCI, cTnI-Ultra, Xpand, Stratus CS), and Roche [4th Generation (Gen), hs]. Manufacturer-derived 99th percentile cutoffs were used to classify results as positive or negative. Alternative 99th percentile cutoffs were tested for some assays. Correlation was assessed using Passing-Bablok linear regression, bias was examined using Bland-Altman difference plots, and concordance/discordance of each method comparison was determined using the McNemar method. Regression slopes ranged from 0.63 to 1.87, y-intercepts from 0.00 to 0.03 ng/mL, and r values from 0.93 to 0.99. The cTnT methods had a slope of 0.93, y-intercept of 0.02 ng/mL, and r value of 0.99. For the cTnI assays, positive, negative, and overall concordance was 76.2%-100%, 66.0%-100%, and 82.9%-98.4%, respectively. Overall concordance between the 4th Gen cTnT and hsTnT assays was 88.9%. A total of 30 of the 78 method comparisons showed significant differences in classification of samples (P <0.001); the iSTAT showed 10, hsTnT showed 9, AccuTnI+3 showed 5, Xpand showed 5, and Stratus CS showed 1. Using alternative 99th percentile cutoffs to those listed by manufacturers lowered the method discordance by 6-fold, from 30 to 5 (all involved iSTAT). These data provide insight into characteristics of cTn methods and will assist the healthcare community in setting expectations for relationships among commercial cTn assays.