Smartphone-based particle tracking velocimetry for the in vitro assessment of coronary flows.

The present study adopts a smartphone-based approach for the experimental characterization of coronary flows. Technically, Particle Tracking Velocimetry (PTV) measurements were performed using a smartphone camera and a low-power continuous wave laser in realistic healthy and stenosed phantoms of left anterior descending artery with inflow Reynolds numbers approximately ranging from 20 to 200. A Lagrangian-Eulerian mapping was performed to convert Lagrangian PTV velocity data to a Eulerian grid. Eulerian velocity and vorticity data obtained from smartphone-based PTV measurements were compared with Particle Image Velocimetry (PIV) measurements performed with a smartphone-based setup and with a conventional setup based on a high-power double-pulsed laser and a CMOS camera. Smartphone-based PTV and PIV velocity flow fields substantially agreed with conventional PIV measurements, with the former characterized by lower average percentage differences than the latter. Discrepancies emerged at high flow regimes, especially at the stenosis throat, due to particle image blur generated by smartphone camera shutter speed and image acquisition frequency. In conclusion, the present findings demonstrate the feasibility of PTV measurements using a smartphone camera and a low-power light source for the in vitro characterization of cardiovascular flows for research, industrial and educational purposes, with advantages in terms of costs, safety and usability.

Acoustic resolution photoacoustic Doppler flowmetry for assessment of patient rectal cancer blood perfusion.

Significance: Photoacoustic Doppler flowmetry offers quantitative blood perfusion information in addition to photoacoustic vascular contrast for rectal cancer assessment. Aim: We aim to develop and validate a correlational Doppler flowmetry utilizing an acoustic resolution photoacoustic microscopy (AR-PAM) system for blood perfusion analysis. Approach: To extract blood perfusion information, we implemented AR-PAM Doppler flowmetry consisting of signal filtering and conditioning, A-line correlation, and angle compensation. We developed flow phantoms and contrast agent to systemically investigate the flowmetry's efficacy in a series of phantom studies. The developed correlational Doppler flowmetry was applied to images collected during in vivo AR-PAM for post-treatment rectal cancer evaluation. Results: The linearity and accuracy of the Doppler flow measurement system were validated in phantom studies. Imaging rectal cancer patients treated with chemoradiation demonstrated the feasibility of using correlational Doppler flowmetry to assess treatment response and distinguish residual cancer from cancer-free tumor bed tissue and normal rectal tissue. Conclusions: A new correlational Doppler flowmetry was developed and validated through systematic phantom evaluations. The results of its application to in vivo patients suggest it could be a useful addition to photoacoustic endoscopy for post-treatment rectal cancer assessment.

Contrast Agent-Free Assessment of Blood Flow and Wall Shear Stress in the Rabbit Aorta using Ultrasound Image Velocimetry.

Blood flow velocity and wall shear stress (WSS) influence and are influenced by vascular disease. Their measurement is consequently useful in the laboratory and clinic. Contrast-enhanced ultrasound image velocimetry (UIV) can estimate them accurately but the need to inject contrast agents limits utility. Singular value decomposition and high-frame-rate imaging may render contrast agents dispensable. Here we determined whether contrast agent-free UIV can measure flow and WSS. In simulation, accurate measurements were achieved with a signal-to-noise ratio of 13.5 dB or higher. Signal intensity in the rabbit aorta increased monotonically with mechanical index; it was lowest during stagnant flow and uneven across the vessel. In vivo measurements with contrast-free and contrast-enhanced UIV differed by 4.4% and 1.9% for velocity magnitude and angle and by 9.47% for WSS. Bland-Altman analysis of waveforms revealed good agreement between contrast-free and contrast-enhanced UIV. In five rabbits, the root-mean-square errors were as low as 0.022 m/s (0.81%) and 0.11 Pa (1.7%). This study indicates that with an optimised protocol, UIV can assess flow and WSS without contrast agents. Unlike contrast-enhanced UIV, contrast-free UIV could be routinely employed.

Aging characteristics of asphalt binders modified with waste tire and plastic pyrolytic chars.

Globally, the growing volume of waste tires and plastics has posed significant concerns about their sustainable and economical disposal. Pyrolysis provides a way for effective treatment and management of these wastes, enabling recovery of energy and produces solid pyrolytic char as a by-product. The use of pyrolytic chars in asphalt binder modification has recently gained significant interest among researchers. As asphalt binder aging influences the cracking, rutting, and moisture damage performance of asphalt binder and the mixtures, evaluation of aging characteristics of char modified asphalt binders is quite important. The main objective of this study is the investigation of the aging characteristics of asphalt binders modified with waste tire pyrolytic char (TPC) and waste plastic pyrolytic char (PPC) through rheological and spectroscopic evaluations. To imitate short-term and long-term aging conditions, the asphalt binders were first treated in a rolling thin film oven (RTFO) and then in a pressure aging vessel (PAV). The aging characteristics were determined using four rheological aging indices based on complex modulus (G*), phase angle (δ), zero shear viscosity (ZSV), and non-recoverable creep compliance (Jnr) from multiple stress creep and recovery (MSCR) test. The fatigue cracking potential was then measured through binder yield energy test (BYET). These parameters were measured through a dynamic shear rheometer. Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H-NMR) spectroscopy analyses were then used to investigate changes in chemical composition due to aging in the char modified binders. Both TPC and PPC improved the high-temperature deformation resistance properties of asphalt binder. The TPC-modified binder showed better aging resistance than the control and PPC-modified binders, based on the different rheological and spectroscopic indices. The pyrolytic char modified binders also demonstrated good fatigue performance.

Are all ulvans equal? A comparative assessment of the chemical and gelling properties of ulvan from blade and filamentous Ulva.

Green seaweeds of the genus Ulva are rich in the bioactive sulfated polysaccharide ulvan. Herein we characterise ulvan from Ulva species collected from the Bay of Plenty, Aotearoa New Zealand. Using standardised procedures, we quantified, characterised, and compared ulvans from blade (U. australis, U. rigida, U. sp. B, and Ulva sp.) and filamentous (U. flexuosa, U. compressa, U. prolifera, and U. ralfsii) Ulva species. There were distinct differences in composition and structure of ulvans between morphologies. Ulvan isolated from blade species had higher yields (14.0-19.3 %) and iduronic acid content (IdoA = 7-18 mol%), and lower molecular weight (Mw = 190-254 kDa) and storage moduli (G' = 0.1-6.6 Pa) than filamentous species (yield = 7.2-14.6 %; IdoA = 4-7 mol%; Mw = 260-406 kDa; G' = 22.7-74.2 Pa). These results highlight the variability of the physicochemical properties of ulvan from different Ulva sources, and identifies a morphology-based division within the genus Ulva.

Flow resistive forces index (QRF): Development and clinical applicability assessment of a novel measure of bladder outlet resistance, aiming to enhance the diagnostic performance of uroflowmetry.

BACKGROUND: Currently, the diagnostic ability of uroflowmetry, the most widely used urodynamic test available for initial assessment of patients with lower urinary tract symptoms (LUTS), is considered limited by its inability to accurately discriminate between the underlying mechanisms of this condition. To improve the diagnostic accuracy of uroflow, we developed a mathematical formula that calculates the flow resistive forces index (QRF), a novel measure of bladder outflow/urethral resistance, and assessed its clinical applicability compared to the maximum flow rate (Qmax ). MATERIALS AND METHODS: A cross-sectional observational study was conducted in a cohort of 61 adult men presenting with voiding dysfunction symptoms, who all underwent free uroflowmetry followed by pressure flow study. The development of the mathematical formula which contains five key uroflowmetry variables (voided volume, flow time, Qmax , average flow rate, and peak flow time) was based on the assumption that urine volume momentum changes during voiding, the concept of diphasic uroflow pattern (acceleration/deceleration), and the urethral resistance factor (URA) equation. Study subjects were classified either as obstructed or nonobstructed according to established urodynamic criteria (linearized passive urethral resistance relation, LinPURR; Abrams-Griffiths number, AGN [also called bladder outlet obstruction index, BOOI]; and URA). Univariate linear correlations, binary logistic regression model, and receiver operating characteristic (ROC) curve statistical analysis were employed (SPSS-22, MedCalc, GraphPad [P < .05]). RESULTS: Outflow obstruction was diagnosed in 50.8% (1 in 2) patients. Univariate analysis, and bivariate linear correlation, binary logistic regression, and ROC curve analyses showed that the QRF was a strong independent predictor of bladder outlet/outflow obstruction (BOO), significantly outperforming Qmax . CONCLUSIONS: QRF index accurately predicts BOO, significantly outperforming the currently widely used bladder outlet obstruction estimator Qmax . Despite potential study limitations (mainly small cohort size and lack of control group), we anticipate that with further study and proper clinical validation, QRF could become a valuable complement to uroflowmetry.

Development and assessment of a stiffness display system for minimally invasive surgery based on smart magneto-rheological elastomers.

In the present study, a solution to address the clinical need for stiffness display during manual and robotic minimally invasive surgery was postulated, developed, and assessed. To this end, a magneto-rheological elastomer-based stiffness display, MiTouch, was designed, developed, and analyzed. The mechanical properties of the MRE and system parameters were identified experimentally, based on which the force-field-stiffness response surface of the smart MRE was characterized. Based on the response surface, a stiffness controller was designed and verified for a set of performance requirements. A heartbeat simulation experiment showed the capability of the system for replicating desired tactile forces through stiffness control. Also, the system successfully attained an arbitrarily selected stiffness (4 N/mm) and maintained it within a bounded range (4.07 ± 0.41 N/mm). A comparison of the system performance with current literature validated its applicability for the proposed medical application.

Assessment of the Flow Field in the HeartMate 3 Using Three-Dimensional Particle Tracking Velocimetry and Comparison to Computational Fluid Dynamics.

Flow fields in rotary blood pumps (RBPs) have a significant influence on hemocompatibility. Because flow characteristics vary with flow rate, different operating conditions play a role. Furthermore, turbulence is crucial in the evaluation of blood damage potential, but the level of turbulence in implantable RBPs is still unknown. In this study, we addressed both research aspects and for the first time measured turbulent flow fields in the HeartMate 3 (HM3) at different operating flows. The averaged, three-dimensional velocity field including fluctuating velocity components in a HM3 with a transparent lower housing was measured using three-dimensional particle tracking velocimetry (3D-PTV). In vitro results were compared with computational fluid dynamic (CFD) simulations for two flow cases, representing the lower and upper physiologic flow range (2.7 and 5.7 L/min), using two different turbulence models that account for fluctuating velocity fields: the k-ω shear stress transport and the Reynolds stress model (RSM). The measurements revealed higher mean and turbulent kinetic energies (TKEs) for the low-flow condition especially within the gap beneath the impeller. Computed mean fields agree well with 3D-PTV for both models, but the RSM predicts the TKE levels better than the k-ω model. Computational fluid dynamic results further show wall shear stresses higher than 150 Pa, a commonly used damage threshold, in the bottom gap for the lower flow condition. In conclusion, the low-flow condition was found to be more prone to blood damage. Furthermore, CFD predictions for turbulence must be carefully experimentally validated.

Advanced blood flow assessment in Zebrafish via experimental digital particle image velocimetry and computational fluid dynamics modeling.

Over the past few decades, Zebrafish has become a widely used vertebrate model for cardiovascular research. Easy genetic manipulation, low cost, high fecundity, embryonic transparency, and ability to survive in the early stages of development without active circulation are among the advantages of Zebrafish. Cardiac malformations can be induced through genetic manipulations for elucidating the influence of mechanobiological stimuli on the development and progress of the cardiovascular diseases. For this purpose, a reliable in vivo assessment of cardiac function and disturbed hemodynamics is required. Therefore, it is necessary to accurately determine the complex blood flow patterns and associated hemodynamic shear stresses within the developing heart and cardiovascular system. In the traditional approach, brightfield microscopy is used to track the motion of cells in two-dimensions (2D). However, with the development of advanced modalities such as light-sheet fluorescent microscopy, it is now possible to perform 4D (three-dimensional space + time) imaging of Zebrafish embryo and larvae. The integration of digital particle image velocimetry (DPIV) and computational fluid dynamics (CFD) provide an opportunity for detailed investigations using in vivo images. In this review, DPIV and CFD methods are explained for blood flow assessment, and recent relevant research findings from Zebrafish studies are summarized.

Uroflowmetry alterations in patients with autosomal dominant polycystic kidney disease.

OBJECTIVE: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a heterogeneous inherited disease characterized by renal and extrarenal manifestations with progressive fluid-filled cyst development leading to end-stage renal disease. Our aim was to evaluate the prevalence of obstructive urological disease in ADPKD patients and possible associations with endothelial dysfunction, nutritional, metabolic and inflammatory markers. PATIENTS AND METHODS: The study included ADPKD patients and control group, who carried out uroflowmetry, an assessment of renal function, metabolic and nutritional parameters and an evaluation of endothelial dysfunction and atherosclerotic markers, such as Renal Resistive Index (RRI), Intima-Media Thickness (IMT) and Flow-Mediated Dilation (FMD). RESULTS: We enrolled 37 ADPKD patients (20 males with 51.0 ± 14.3 years) and 34 control group (18 males with 60.7 ± 14.4 years). We showed a significant reduction in Max Flow Rate (Qmax) (p ≤ 0.001), age (p = 0.006), FMD (p = 0.023) and Voiding Volume (p = 0.053), in addition to a significant increase in Voiding Time and Diastolic Blood Pressure (p ≤ 0.001, p = 0.049; respectively) in ADPKD patients with respect to control group. Moreover, we found a negative correlation between Qmax and creatinine (r= -0.44, p = 0.007), RRI (r= -0.49, p ≤0.001) and intact Parathyroid Hormone (r = -0.329, p = 0.046), while we found a positive correlation between Qmax and MDRD (r = 0.327, p = 0.048) and between Voiding Time and serum uric acid (r= 0.34, p = 0.039) in ADPKD patients with respect to control group. CONCLUSIONS: In our study, we showed an elevated prevalence of urological functional diseases in ADPKD patients; therefore, we suggest to include uroflowmetry in the assessment of these patients, considering the non-invasiveness, repeatability and low cost of the exam. An early intervention could slow down the progression of renal damage and an early screening of the main cardiovascular risk factors could reduce the high morbidity and mortality in ADPKD patients.

Roadmap to 3D-Printed Oral Pharmaceutical Dosage Forms: Feedstock Filament Properties and Characterization for Fused Deposition Modeling.

Application of additive manufacturing techniques (3D printing) for mass-customized products has boomed in the recent years. In pharmaceutical industry and research, the interest has grown particularly with the future scenario of more personalized medicinal products. Understanding a broad range of material properties and process behavior of the drug-excipient combinations is necessary for successful 3D printing of dosage forms. This commentary reviews recent 3D-printing studies by fused deposition modeling (FDM) technique in pharmaceutical sciences, extending into the fields of polymer processing and rapid prototyping, where more in-depth studies on the feedstock material properties, modeling, and simulation of the FDM process have been performed. A case study of a model oral dosage form from custom-prepared indomethacin-polycaprolactone feedstock filament was used as an example in the pharmaceutical context. The printability was assessed in the different process steps: preparation of customized filaments for FDM, filament feeding, deposition, and solidification. These were linked with the rheological, thermal, and mechanical properties and their characterization, relevant for understanding the printability of drug products by FDM.

Intraoperative Bypass Graft Flow Measurement With Transit Time Flowmetry: A Clinical Assessment.

BACKGROUND: Guidelines advocate transit time flowmetry (TTFM) for intraoperative graft patency verification during coronary artery bypass graft surgery (CABG), but studies on accuracy and precision of the TTFM technique are few. In an observational study of CABG patients, we analyzed covariation of left internal mammary artery (LIMA) blood flow with TTFM and free flow measurements. METHODS: Covariation of TTFM and free blood flows was evaluated in 60 patients undergoing CABG using the LIMA as one of the conduits. With LIMA flow measurements routinely performed before and after vasodilation, results are based on 120 paired intraoperative measurements. RESULTS: As demonstrated by a combined approach of regression and Bland-Altman analysis for the two flow situations, TTFM was higher than free flow in 64% of measurements, with an overestimation by TTFM of 7.1% ± 16.3% in the overall cohort (prevasodilation), statistically carried by measurements with 4-mm probes (overestimation by 13.3% ± 15.4%, both p < 0.01). In a multiregression analysis, oversizing of the TTFM probe (odds ratio 9.56, 95% confidence interval: 2.03 to 45.10, p = 0.004) and high flows (odds ratio 1.02, 95% confidence interval: 1.01 to 1.04, p < 0.001) were independent determinants of flow overestimation by TTFM, although in the Bland-Altman analysis no systematic overestimation was seen in the postvasodilation situation. In a receiver-operating characteristics analysis, optimal cutoff value as determined from Youden's index for assuming flow overestimation was 68 mL/min. CONCLUSIONS: Overall, with slight overall overestimation of 7.1%, TTFM is an accurate indicator of LIMA blood flow during CABG, with a clinically acceptable precision. Overestimation may be expected with flows greater than 68 mL/min, but most importantly, in situations with oversized TTFM probes.

Matching material and cellular timescales maximizes cell spreading on viscoelastic substrates.

Recent evidence has shown that, in addition to rigidity, the viscous response of the extracellular matrix (ECM) significantly affects the behavior and function of cells. However, the mechanism behind such mechanosensitivity toward viscoelasticity remains unclear. In this study, we systematically examined the dynamics of motor clutches (i.e., focal adhesions) formed between the cell and a viscoelastic substrate using analytical methods and direct Monte Carlo simulation. Interestingly, we observe that, for low ECM rigidity, maximum cell spreading is achieved at an optimal level of viscosity in which the substrate relaxation time falls between the timescale for clutch binding and its characteristic binding lifetime. That is, viscosity serves to stiffen soft substrates on a timescale faster than the clutch off-rate, which enhances cell-ECM adhesion and cell spreading. On the other hand, for substrates that are stiff, our model predicts that viscosity will not influence cell spreading, since the bound clutches are saturated by the elevated stiffness. The model was tested and validated using experimental measurements on three different material systems and explained the different observed effects of viscosity on each substrate. By capturing the mechanism by which substrate viscoelasticity affects cell spreading across a wide range of material parameters, our analytical model provides a useful tool for designing biomaterials that optimize cellular adhesion and mechanosensing.

Formulation and evaluation of diclofenac controlled release matrix tablets made of HPMC and Poloxamer 188 polymer: An assessment on mechanism of drug release.

In this study, hydrophilic hydroxypropyl methylcellulose matrices with various concentrations of Poloxamer 188 were used in the development of oral controlled release tablets containing diclofenac sodium. Four formulations of hydrophilic matrix tablets containing 16.7% w/w HPMC and 0, 6.7, 16.7 and 25.0% w/w Poloxamer 188, respectively, were developed. Tablets were prepared by direct compression and characterized for diameter, hardness, thickness, weight and uniformity of content. The influence of various blends of hydroxypropyl methylcellulose and Poloxamer 188 on the in vitro dissolution profile and mechanism of drug release of was investigated. In the four formulations, the rate of drug release decreased with increasing the concentration of Poloxamer 188 at the initial dissolution stages due to the increase in the apparent viscosity of the gel diffusion layer. However, in the late dissolution stages, the rate of drug release increased with increasing Poloxamer 188 concentration due to the increase in wettability and dissolution of the matrix. The kinetic of drug release from the tablets followed non-Fickian mechanism, as predicted by Korsmeyer-Peppas model, which involves diffusion through the gel layer and erosion of the matrix system.

Identification of the State of Maximal Hyperemia in the Assessment of Coronary Fractional Flow Reserve Using Non-Invasive Electrical Velocimetry.

Previous research revealed that, in patients with coronary pressure-derived fractional flow reserve (FFR) in the 'grey zone' (0.75-0.85), repeated FFR assessments sometimes yield conflicting results. One of the causes of the fluctuations in FFR values around the grey zone may be imprecise identification of the point where maximal hyperemia is achieved. Identification of the state of maximal hyperemia during assessment of FFR can be challenging. This study aimed to determine whether non-invasive electrical velocimetry (EV) can be used to identify the state of maximal hyperemia.Stroke volume (SV), SV variation (SVV), and systemic vascular resistance index (SVRI) were determined by EV in 15 patients who underwent FFR assessment. Time intervals from initiation of adenosine infusion to achieving maximal hyperemia (timemFRR), as well as to achieving maximal cardiac output (CO), SV, SVV, and SVRI (timemCO, timemSV, timemSVV, and timemSVRI, respectively), were determined. TimemCO and timemSVV were closer to timemFRR than other values (timemSVV/timemFRR versus timemSVRI/timemFRR = 1.03 ± 0.2 versus 1.36 ± 0.4, P < 0.05). The maximum of SV was difficult to determine owing to considerable variations, but the maximum of SVV was clearly recognized. TimemCO and timemSVV were significantly correlated with timemFFR, with timemSVV showing a stronger correlation than timemSV (timemSVV: r = 0.92, P < 0.01; timemCO: r = 0.80, P < 0.01).Maximal SVV is reached close to maximal hyperemia. Monitoring of SVV with non-invasive EV during FFR assessment can help identify the state of maximal hyperemia.

[Flowmetric assessment of coronary bypass grafts in the conditions of artificial circulation and on the beating heart].

Advantages and shortcomings of aortocoronary bypass grafting on the beating heart and in the conditions of artificial circulation (AC) have long been discussed. The data on patency of bypass grafts in the remote period are indicative of comparable results of operations with and without AC or advantages of using AC. In order to determine benefits of each method it is necessary to reveal intraoperative predictors of bypass grafts occlusion in the remote period. We analyzed the results of ultrasound flowmetry of the blood flow through the left internal thoracic artery during bypass grafting of the anterior descending artery with the use of AC and on the beating heart. A retrospective study included a total of 352 patients subdivided into 2 groups: Group One was composed of 120 patients undergoing surgery in the conditions of AC and Group Two comprised 232 patients subjected to similar operations on the beating heart. Blood flow was measured with the help of flowmeter VeryQ MediStim® after termination of AC and inactivation of heparin by protamine, with systolic pressure of 100-110 mm Hg. There were no statistically significant differences between the groups by the diameter and degree of stenosis of the anterior descending artery, diameter of the left internal thoracic artery. The mean volumetric blood flow velocity (Qmean) along the shunts in Group One was higher (p=0.01). No statistically significant differences by the pulsatility index (PI) between the groups were revealed (p=0.2). A conclusion was drawn that coronary bypass grafting of the anterior descending artery by the left internal thoracic artery in the conditions of artificial circulation made it possible to achieve higher volumetric velocity of blood flow through the conduit as compared with operations on the beating heart, with similar resistance index. The immediate results of the operations with the use of the both techniques did not differ.

Rheology and microstructure of binary mixed gel of rice bran protein-whey: effect of heating rate and whey addition.

BACKGROUND: Rice bran protein (RBP) is a valuable plant protein which has unique nutritional and hypoallergenic properties. Whey proteins have wide applications in the food industry, such as in dairy, meat and bakery products. RESULTS: Whey protein concentrate (WPC), RBP and their mixtures at different ratios (1:1, 1:2, 1:5 and 1:10 w/w) were heated from 20 to 90 °C at different heating rates (0.5, 1, 5 and 10 °C min(-1) ). The storage modulus (G') and gelling point (Tgel ) of WPC were higher than those of RBP, indicating the good ability of WPC to develop stiffer networks. By increasing the proportion of WPC in mixed systems, G' was increased and Tgel was reduced. Nevertheless, the elasticity of all binary mixtures was lower than that of WPC alone. Tgel and the final G' of RBP-WPC blends were increased by raising the heating rate. The RBP-WPC mixtures developed more elastic gels than RBP alone at different heating rates. RBP had a fibrillar and lentil-like structure whose fibril assembly had smaller structures than those of WPC. CONCLUSION: The gelling structure of the mixed gel of WPC-RBP was improved by adding WPC. Indeed, by adding WPC, gels tended to show syneresis and had lower water-holding capacity. Furthermore, the gel structure was produced by adding WPC to the non-gelling RBP, which is compatible with whey and can be applied as a functional food for infants and/or adults. © 2015 Society of Chemical Industry.

Error analysis and assessment of unsteady forces acting on a flapping wing micro air vehicle: free flight versus wind-tunnel experimental methods.

An accurate knowledge of the unsteady aerodynamic forces acting on a bio-inspired, flapping-wing micro air vehicle (FWMAV) is crucial in the design development and optimization cycle. Two different types of experimental approaches are often used: determination of forces from position data obtained from external optical tracking during free flight, or direct measurements of forces by attaching the FWMAV to a force transducer in a wind-tunnel. This study compares the quality of the forces obtained from both methods as applied to a 17.4 gram FWMAV capable of controlled flight. A comprehensive analysis of various error sources is performed. The effects of different factors, e.g., measurement errors, error propagation, numerical differentiation, filtering frequency selection, and structural eigenmode interference, are assessed. For the forces obtained from free flight experiments it is shown that a data acquisition frequency below 200 Hz and an accuracy in the position measurements lower than ± 0.2 mm may considerably hinder determination of the unsteady forces. In general, the force component parallel to the fuselage determined by the two methods compares well for identical flight conditions; however, a significant difference was observed for the forces along the stroke plane of the wings. This was found to originate from the restrictions applied by the clamp to the dynamic oscillations observed in free flight and from the structural resonance of the clamped FWMAV structure, which generates loads that cannot be distinguished from the external forces. Furthermore, the clamping position was found to have a pronounced influence on the eigenmodes of the structure, and this effect should be taken into account for accurate force measurements.

Objective Assessment of the Rheological Muscle Property in the Treatment of Fibromyalgia.

Fibromyalgia (FM), clinical condition characterized by several signs and symptoms such as widespread pain, trigger point, morning stiffness and extreme tiredness for scarce hours of sleep, is linked to several changes in several brain neurotransmitters, particularly serotonin and norepinephrine. Consequently, the Neural Vegetative System works more and so it generates an exaggerated muscular contraction, sweating and constriction of blood vessels. The aim of our study was to treat a selected group of female patients suffering from FM with duloxetine with physiotherapy. We used two clinical scales (VAS and FIQ) and an objective evaluation such as myometric. The analysis of the data Myoton used during any inspection showed a statistically significant reduction in the values of muscle tone in each district analyzed. This finding was also confirmed by the patients themselves who have experienced a significant welfare and less muscle tension in different locations, as evidenced by data obtained from the clinical scales used by us. In addition, our patients were thought to be satisfied with the improvements not only subjective, but also with the objective witnessed myometry, making them a share of the study and feeling constantly monitored for treatment aimed at a real reduction in muscle stiffness. In conclusion, our study demonstrates combined treatment duloxetine- physiotherapy effectively reduces a symptom often disabling and particularly troublesome in patients with FM as the exaggerated muscle contraction.

Validation of stroke volume and cardiac output by electrical interrogation of the brachial artery in normals: assessment of strengths, limitations, and sources of error.

The goal of this study is to validate a new, continuous, noninvasive stroke volume (SV) method, known as transbrachial electrical bioimpedance velocimetry (TBEV). TBEV SV was compared to SV obtained by cardiac magnetic resonance imaging (cMRI) in normal humans devoid of clinically apparent heart disease. Thirty-two (32) volunteers were enrolled in the study. Each subject was evaluated by echocardiography to assure that no aortic or mitral valve disease was present. Subsequently, each subject underwent electrical interrogation of the brachial artery by means of a high frequency, low amplitude alternating current. A first TBEV SV estimate was obtained. Immediately after the initial TBEV study, subjects underwent cMRI, using steady-state precession imaging to obtain a volumetric estimate of SV. Following cMRI, the TBEV SV study was repeated. Comparing the cMRI-derived SV to that of TBEV, the two TBEV estimates were averaged and compared to the cMRI standard. CO was computed as the product of SV and heart rate. Statistical methods consisted of Bland-Altman and linear regression analysis. TBEV SV and CO estimates were obtained in 30 of the 32 subjects enrolled. Bland-Altman analysis of pre- and post-cMRI TBEV SV showed a mean bias of 2.87 % (2.05 mL), precision of 13.59% (11.99 mL) and 95% limits of agreement (LOA) of +29.51% (25.55 mL) and -23.77% (-21.45 mL). Regression analysis for pre- and post-cMRI TBEV SV values yielded y = 0.76x + 25.1 and r(2) = 0.71 (r = 0.84). Bland-Altman analysis comparing cMRI SV with averaged TBEV SV showed a mean bias of -1.56% (-1.53 mL), precision of 13.47% (12.84 mL), 95% LOA of +24.85% (+23.64 mL) and -27.97% (-26.7 mL) and percent error = 26.2 %. For correlation analysis, the regression equation was y = 0.82x + 19.1 and correlation coefficient r(2) = 0.61 (r = 0.78). Bland-Altman analysis of averaged pre- and post-cMRI TBEV CO versus cMRI CO yielded a mean bias of 5.01% (0.32 L min(-1)), precision of 12.85% (0.77 L min(-1)), 95% LOA of +30.20 % (+0.1.83 L min(-1)) and -20.7% (-1.19 L min(-1)) and percent error = 24.8%. Regression analysis yielded y = 0.92x + 0.78, correlation coefficient r(2) = 0.74 (r = 0.86). TBEV is a novel, noninvasive method, which provides satisfactory estimates of SV and CO in normal humans.