Peripheral bronchial obstruction evaluation in patients with asthma by lung sound analysis and impulse oscillometry

Background

Computer-aided lung sound analysis (LSA) has been reported to be useful for evaluating airway inflammation and obstruction in asthma patients. We investigated the relation between LSA and impulse oscillometry with the evaluation of peripheral airway obstruction.

Early functional improvement after stroke correlates with cardiovascular fitness

Cardiovascular fitness exerts directly beneficial effects on functional and cognitive outcomes in patients of chronic stroke. However, the effect of early rehabilitation on cardiovascular function has not yet been thoroughly examined. We tested whether complementary rehabilitation program could influence cardiovascular fitness in an early stage of stroke patients. The associations for post-acute stroke functional recovery with cardiovascular fitness were explored. Thirty-seven patients with mean poststroke interval of 8.6 ± 3.8 days underwent inpatient rehabilitation of 22.8 ± 3.8 days. Functional outcomes of 15.3 points (17.2%) in functional independence measure improved after rehabilitation program. The therapeutic cardiovascular fitness was determined in ramp exercise test on a cycling ergometer. Peak oxygen uptake ($\dot{V}$O_2peak) significantly increased by 24.8% after early stroke rehabilitation. Multivariate regression analysis was performed to assess for associations of functional improvement with respect to change in $\dot{V}$O_2peak and extremities motor impairment. $\dot{V}$O_2peak gain accounted for more functional recovery than extremities motor improvement (R² = 0.42). In conclusion, these results suggest that cardiovascular fitness appears to increase after complementary program in early stroke rehabilitation, and better cardiovascular fitness may be associated with greater functional improvement.     

Exercise Capacity and Ventilatory Efficiency in Patients With Pulmonary Embolism After Short Duration of Anticoagulation Therapy

BackgroundAlthough anticoagulation therapy can reduce the risk for pulmonary embolism (PE) recurrence, symptoms such as exertional dyspnea or pain can persist for several months to years. Therefore, we aimed to assess the improvement of ventilatory efficiency and exercise capacity during cardiopulmonary exercise test in PE patients after short duration of anticoagulant therapy.Materials and MethodsPulmonary function testing, arterial blood gas analysis and cardiopulmonary exercise test were performed in 30 PE patients after anticoagulant therapy of 4 weeks (early phase) and after 6 months (late phase). In addition, another 30 healthy volunteers underwent the same tests.ResultsPercentage of forced vital capacity (FVC %pred) improvement was evident in the PE group (P < 0.01) after 6 months of treatment. Peak Load, peak Load %pred, peak oxygen uptake ($\stackrel{\circ }{\mathrm{V}}{\mathrm{O}}_2$), peak $\stackrel{\circ }{\mathrm{V}}{\mathrm{O}}_2$%pred increased significantly after treatment for 6 months (P < 0.01), while lowest minute ventilation in relation to carbon dioxide production ($\stackrel{\circ }{\mathrm{V}}\mathrm{E}$ / $\stackrel{\circ }{\mathrm{V}}\mathrm{C}{\mathrm{O}}_2$) and lowest $\stackrel{\circ }{\mathrm{V}}\mathrm{E}$ / $\stackrel{\circ }{\mathrm{V}}\mathrm{C}{\mathrm{O}}_2$ %pred decreased significantly (P = 0.001). In PE group, the increment of peak $\stackrel{\circ }{\mathrm{V}}{\mathrm{O}}_2$ %pred from 4 weeks to 6 months correlated with the decrease of lowest $\stackrel{\circ }{\mathrm{V}}\mathrm{E}$ / $\stackrel{\circ }{\mathrm{V}}\mathrm{C}{\mathrm{O}}_2$ %pred (r = 0.639, P < 0.001) but not the increment of FVC %pred (r = 0.058, P = 0.769).ConclusionsExercise capacity improved significantly and there was a gradual improvement in ventilatory efficiency after 6 months of anticoagulation therapy.     

Atrial structure and function in middle‐aged,physically‐active males and females: A cardiac magnetic resonance study

Recent studies have reported on an association between endurance sport, atrial enlargement and the development of lone atrial fibrillation in younger, male cohorts. The atrial morphology and function of middle‐aged, physically‐active males and females have not been well studied. We hypothesized that middle‐aged males would demonstrate larger left atrium (LA) and right atrium (RA) volumes compared to females, but atrial function would not differ. LA and RA volume and function were evaluated at rest in healthy adults, using a standardized 3.0Tesla cardiac magnetic resonance protocol. Physical activity, medical history, and maximal oxygen consumption (V˙O2peak) were also assessed. Physically‐active, middle‐aged men (n = 60; 54 ± 5 years old) and women (n = 30; 54 ± 5 years old) completed this study. Males had a higher body mass index, systolic blood pressure, and V˙O2peak than females (p < .05 for all), despite similar reported physical activity levels. Absolute and BSA and height‐indexed LA and RA maximum volumes were higher in males relative to females, despite no differences in ejection fractions (p < .05 for all). In multivariable regression, male sex p < .001) and V˙O2peak (p = .004) were predictors of LA volume (model R ² = 0.252), whereas V˙O2peak (p < .001), male sex (p = .03), and RV EF (p < .05) were predictors of RA volume (model R ² = 0.377). While middle‐aged males exhibited larger atrial volumes relative to females, larger, prospective studies are needed to explore the magnitude of physiologic atrial remodeling and functional adaptations in relation to phenotypic factors.     

Dissolution of Portlandite in Pure Water: Part 2 Atomistic Kinetic Monte Carlo (KMC) Approach

Portlandite, as a most soluble cement hydration reaction product, affects mechanical and durability properties of cementitious materials. In the present work, an atomistic kinetic Monte Carlo (KMC) upscaling approach is implemented in MATLAB code in order to investigate the dissolution time and morphology changes of a hexagonal platelet portlandite crystal. First, the atomistic rate constants of individual Ca dissolution events are computed by a transition state theory equation based on inputs of the computed activation energies (ΔG*) obtained through the metadynamics computational method (Part 1 of paper). Four different facets (100 or 1¯00, 010 or 01¯0, 1¯10 or 11¯0, and 001 or 001¯) are considered, resulting in a total of 16 different atomistic event scenarios. Results of the upscaled KMC simulations demonstrate that dissolution process initially takes place from edges, sides, and facets of 010 or 01¯0 of the crystal morphology. The steady-state dissolution rate for the most reactive facets (010 or 01¯0) was computed to be 1.0443 mol/(s cm²); however, 0.0032 mol/(s cm²) for 1¯10 or 11¯0, 2.672 × 10⁻⁷ mol/(s cm²) for 001 or 001¯, and 0.31 × 10⁻¹⁶ mol/(s cm²) for 100 or 1¯00 were represented in a decreasing order for less reactive facets. Obtained upscaled dissolution rates between each facet resulted in a huge (16 orders of magnitude) difference, reflecting the importance of crystallographic orientation of the exposed facets.     

Crystallographic Calculations and First-Principles Calculations of Heterogeneous Nucleation Potency of γ-Fe on La2O2S Particles

Rare earth (RE) inclusions with high melting points as heterogeneous nucleation in liquid steel have stimulated many recent studies. Evaluating the potency of RE inclusions as heterogeneous nucleation sites of the primary phase is still a challenge. In this work, the edge-to-edge matching (E2EM) model was employed to calculate the atomic matching mismatch and predict the orientation relationship between La₂O₂S and γ-Fe from a crystallographic point of view. A rough orientation relationship (OR) was predicted with the minimum values of fr=9.43% and fd=20.72% as follows: [21¯1¯0]La2O2S∥[100]γ-Fe and (0003¯)La2O2S∥(002¯)γ-Fe. The interface energy and bonding characteristics between La₂O₂S and γ-Fe were calculated on the atomic scale based on a crystallographic study using the first-principles calculation method. The calculations of the interface energy showed that the S-terminated and La(S)-terminated interface structures were more stable. The results of difference charge density, electron localization function (ELF), the Bader charges and the partial density of states (PDOS) study indicated that the La(S)-terminated interface possessed metallic bonds and ionic bonds, and the S-terminated interface exhibited metallic bond and covalent bond characteristics. This work addressed the stability and the characteristics of the La₂O₂S/γ-Fe interface structure from the standpoint of crystallography and energetics, which provides an effective theoretical support to the study the heterogeneous nucleation mechanism. As a result, La₂O₂S particles are not an effective heterogeneous nucleation site for the γ-Fe matrix from crystallography and energetics points of view.     

Dislocation-Governed Plastic Deformation and Fracture Toughness of Nanotwinned Magnesium

In this work, the plastic deformation mechanisms responsible for mechanical properties and fracture toughness in {101¯2}<101¯1¯>nanotwinned (NT). magnesium is studied by molecular dynamics (MD) simulation. The influence of twin boundary (TBs) spacing and crack position on deformation behaviors are investigated. The microstructure evolution at the crack tip are not exactly the same for the left edge crack (LEC) and the right edge crack (REC) models according to calculations of the energy release rate for dislocation nucleation at the crack tip. The LEC growth initiates in a ductile pattern and then turns into a brittle cleavage. In the REC model, the atomic decohesion occurs at the crack tip to create a new free surface which directly induces a brittle cleavage. A ductile to brittle transition is observed which mainly depends on the competition between dislocation motion and crack growth. This competition mechanism is found to be correlated with the TB spacing. The critical values are 10 nm and 13.5 nm for this transition in LEC and REC models, respectively. Essentially, the dislocation densities affected by the TB spacing play a crucial role in the ductile to brittle transition.     

Évaluation à l’effort d’une nouvelle méthode de mesure du débit cardiaque basée sur l’analyse de l’onde de pouls (comparaison EsCCO® vs Physioflow®)

ObjectivesEsCCO is a novel non-invasive continuous cardiac output monitoring system based on pulse wave transit time already validated at rest. The aim of our study was to compare cardiac output measurements obtained simultaneously by EsCCO^® ($\dot{Q}cOP$) and impedance cardiography (Physioflow^® ; $\dot{Q}cIMP$), in healthy subjects.Patients and methodsEight healthy subjects (age: 31 ± 9 years, weight: 76 ± 10 kg, height: 179 ± 5 cm) realized two exercise tests: an incremental ergocycle test performed until exertion (P_max = 269 ± 48 W) and a constant load exercise (P = 163 ± 27 W). Comparison between measurements ($\dot{Q}cOP$ versus $\dot{Q}cIMP$) obtained during the first test allowed to evaluate the accuracy of the device. Reliability was determined on three repeated measures during the second test, realized at ventilatory threshold.ResultsCorrelation coefficient between both methods is 0.88 (P < 0.01). Mean difference is 0.04 ± 1.49 L/min (95 % limits of agreement: +2.94 to −3.00 L/min) and only 3/74 measures are not included between the limits of agreement. At high intensity and for cardiac output over than 15 L/min, $\dot{Q}cOP$ signal is lost in almost half the time. Concerning reliability, reproducibility coefficient is 0.87 (P < 0.05), only 1.8 % of this variability is due to the method.ConclusionEsCCO^® measurements are accurate, reliable and allow a good estimation of cardiac output on healthy subjects. The signal lost observed for high cardiac output levels (>15 L/min) can limit its utilization during very high intensity exercise.     

Unraveling the Phase Stability and Physical Property of Modulated Martensite in Ni2Mn1.5In0.5 Alloys by First-Principles Calculations

Large magnetic field-induced strains can be achieved in modulated martensite for Ni-Mn-In alloys; however, the metastability of the modulated martensite imposes serious constraints on the ability of these alloys to serve as promising sensor and actuator materials. The phase stability, magnetic properties, and electronic structure of the modulated martensite in the Ni₂Mn_1.5In_0.5 alloy are systematically investigated. Results show that the 6M and 5M martensites are metastable and will eventually transform to the NM martensite with the lowest total energy in the Ni₂Mn_1.5In_0.5 alloy. The physical properties of the incommensurate 7M modulated martensite (7M–IC) and nanotwinned 7M martensite (7M−(52¯)2) are also calculated. The austenite (A) and 7M−(52¯)2 phases are ferromagnetic (FM), whereas the 5M, 6M, and NM martensites are ferrimagnetic (FIM), and the FM coexists with the FIM state in the 7M–IC martensite. The calculated electronic structure demonstrates that the splitting of Jahn–Teller effect and the strong Ni–Mn bonding interaction lead to the enhancement of structural stability.     

Low-Reynolds-number,biflagellated Quincke swimmers with multiple forms of motion

In the limit of zero Reynolds number (Re), swimmers propel themselves exploiting a series of nonreciprocal body motions. For an artificial swimmer, a proper selection of the power source is required to drive its motion, in cooperation with its geometric and mechanical properties. Although various external fields (magnetic, acoustic, optical, etc.) have been introduced, electric fields are rarely utilized to actuate such swimmers experimentally in unbounded space. Here we use uniform and static electric fields to demonstrate locomotion of a biflagellated sphere at low Re via Quincke rotation. These Quincke swimmers exhibit three different forms of motion, including a self-oscillatory state due to elastohydrodynamic–electrohydrodynamic interactions. Each form of motion follows a distinct trajectory in space. Our experiments and numerical results demonstrate a method to generate, and potentially control, the locomotion of artificial flagellated swimmers.

In a Newtonian fluid, locomotion of microswimmers requires nonreciprocal body motions (1–3). Bacteria or eukaryotic cells achieve this by beating or rotating their slender hair-like organelles, flagella (4, 5) or cilia (6), powered by molecular motors. Mimicking these organisms, artificial swimmers propelled by rotating helices (7, 8) or whipping filaments (9–12) have been fabricated. They are commonly driven by an external power source such as a magnetic field (7–9, 13, 14), sound (15), light (16, 17), and biological materials (12). However, there are very few electrically powered microswimmers (18–20), although electric fields have been exploited to drive other active systems (21–26) via a phenomenon called Quincke rotation (27).Quincke rotation originates from an electrohydrodynamic instability (28–30). Submerged in a liquid with permittivity εl and conductivity σl, a spherical particle with permittivity εs and electric conductivity σs is polarized under a uniform, steady electric field E→. When the particle is stationary, the induced dipole p→ due to the free charges is parallel or antiparallel to E→ (Fig. 1A): if the particle’s relaxation time τs=εs/σs is shorter than that of the ambient liquid, τl=εl/σl, p→ points in the same direction as E→; when τs>τl, p→ is opposite to E→, which generates an electric torque Γ→Q=p→×E→ that amplifies any angular perturbation. However, due to the resisting viscous torque Γ→μ, the system becomes unstable only when E=|E→| exceeds a threshold Ec. This instability causes the particle to rotate with a constant angular velocity ω:ω=1τEEc2−1,[1]where τ=εs+2εlσs+2σl is the relaxation time of the system (see SI Appendix, SI Text, or refs. 28, 29, 31 for derivation), and the rotational axis can be in any direction perpendicular to E→. During steady-state Quincke rotation, there is a constant angle between p→ and E→ (Fig. 1A), which results in a nonzero Γ→Q.Open in a separate windowFig. 1.Quincke rotation and the experimental setup. (A) Distribution of free charge and the corresponding dipole p→ on a sphere in a uniform, steady electric field E→. The sphere is (Left) stationary, (Middle) stationary, and (Right) rotating with a constant angular velocity ω. (B) A sketch of the biflagellated swimmer. Dashed lines show the roll axis (blue) and pitch axis (green). (C) A schematic illustration of the experimental setup.Recently, a flagellated swimmer in unbounded space driven by Quincke rotation has been proposed theoretically (32, 33). In light of the theory, we built a laboratory prototype, a biflagellated Quincke swimmer composed of a spherical particle and two attached elastic filaments, as shown in Fig. 1B, and systematically studied its behaviors at low Reynolds number (Re<0.3; Materials and Methods). Varying the electric field E→ and the angle between the two filaments, the Quincke swimmers exhibit three distinct forms of motion—two unidirectional rotations, which we call roll and pitch, and a self-oscillatory rotation, due to the balances between the electrical, elastic, and hydrodynamic torques, resulting in distinct trajectories in space. Surprisingly, it was recently reported (34) that spherical bacteria Magnetococcus marinus exhibit a similar pitch motion as our biflagellated artificial swimmers, which is rarely adopted by other microorganisms. Moreover, we found a threshold tail angle that separates the swimmers’ preferred forms of rotation, and within a small range close to this threshold angle, the three forms of motion coexist.