Contributors:Yale Tung-Chen, Miguel Ángel Roig-Osca
Caseous calcification of the mitral annulus is an underdiagnosed disease, which can be associated with aging and cardiovascular risk factors: hypertension, diabetes, dyslipidemia or end-stage renal disease. This disease should be considered in the differential diagnosis in order to avoid unnecessary tests or even surgery.
Contributors:Christian T. Herbst, Jakob Unger, Hanspeter Herzel, Jan G. Švec, Jörg Lohscheller
In a recent publication, the phasegram, a bifurcation diagram over time, has been introduced as an intuitive visualization tool for assessing the vibratory states of oscillating systems. Here, this nonlinear dynamics approach is augmented with quantitative analysis parameters, and it is applied to clinical laryngeal high-speed video (HSV) endoscopic recordings of healthy and pathological phonations.
Contributors:Wei Lu, Huanjun Li, Bo Huo, Zihui Meng, Min Xue, Lili Qiu, Shaopeng Ma, Zequn Yan, Chunmei Piao, Xiaoqin Ma
A label free and easy-to-prepare optical sensor with high mechanical strength for the fast and visible response to tension and pH variables was reported. An elastic nanocomposite hydrogel was successfully fabricated by in situ free-radical co-polymerization of N,N-dimethylacrylamide (DMAA), acrylic acid (AA) and aluminum oxide nanoparticles (Al2O3 NPs). DMAA and AA could form effective cross-linkage with Al2O3 NPs via hydrogen binding, electrostatic interaction and bidentate bridging. By encapsulating polymethyl methacrylate (PMMA) colloidal arrays into the hydrogels, the optical nanocomposite hydrogels (ONHs) can be easily obtained. This three-dimensionally ordered array exhibits a stop band, and the optical hydrogels can tune the bright color from blue to cyan, green, yellow green, yellow, orange and then finally red by mechanical stimulation of uniaxial tension within 50% strain following Bragg law. The mechanical and optical properties can be adjusted via changing the fraction of AA and polymerization time. Meanwhile, the mechanical and optical responses were reversible for more than 10 times without deterioration. Besides, this material has rapid response to the changing of pH and the full-color change was observed. Owing to the high biocompatibility of nanocomposite hydrogel (NC gel) system and the excellent mechanical strength and water-stability of these ONHs, this optical sensor have high potential to be applied in biomedical field as tension or pH sensor for the intraocular pressure measurement and tonometry and blood gas analysis.
Contributors:Peng Chen, Xiaojun Feng, Dongjuan Chen, Chao Liu, Wei Du, Bi-Feng Liu
In this paper, a new microfluidic approach, termed as gated pinched-flow (GPF), was developed for investigating cell-to-cell signaling dynamics coupling with optical imaging. It takes both advantages of conventional hydrodynamic gating and focusing, enabling precise on-chip chemical stimulation or perfusion upon targeted single cells among cells populations with high temporal (<50ms) and spatial resolution. Theoretical model for GPF was first established and further validated by both numerical simulations and experiments. Stimulation of single HeLa cells was investigated to demonstrate the capability of the GPF for localized chemical stimulations of target single cells without interfering with adjacent cells. Guided by GPF, ATP-activated propagation of intercellular calcium waves (ICWs) among the seeded NIH-3T3 cells in the microchannel was then imaged with high repeatability. Inhibition investigations verified that those cell-to-cell calcium signals depended upon direct cytosolic transfer of molecules via gap junctions. The developed microfluidic method opens up a new avenue for cell-to-cell signaling studies and drug screening.
Electrochemical techniques have been widely utilized for evaluation of oxygen consumption of cells. For high throughput cell analysis and imaging, several electrode-array devices have been developed. However, it is difficult to incorporate many sensors into a small area using a simple arrangement. In the present study, we developed a novel molecular electrochemical switching element for the incorporation of many sensors for detection of oxygen consumption of cells. The switching element is based on the competition of molecular consumption at an electrode pair. The switching elements are incorporated into an electrochemical imaging device, so that n2 electrochemical sensors are prepared with only 2n connector pads. The device was then applied to evaluate the respiratory activity of cell aggregates. The detection system is a useful tool for the electrochemical imaging of cell respiratory activity without any damage to samples.
Contributors:Mark J. Ablowitz, Ali Demirci, Yi-Ping Ma
Dispersive shock waves (DSWs) in the Kadomtsev–Petviashvili (KP) equation and two dimensional Benjamin–Ono (2DBO) equation are considered using step like initial data along a parabolic front. Employing a parabolic similarity reduction exactly reduces the study of such DSWs in two space one time (2+1) dimensions to finding DSW solutions of (1+1) dimensional equations. With this ansatz, the KP and 2DBO equations can be exactly reduced to the cylindrical Korteweg–de Vries (cKdV) and cylindrical Benjamin–Ono (cBO) equations, respectively. Whitham modulation equations which describe DSW evolution in the cKdV and cBO equations are derived and Riemann type variables are introduced. DSWs obtained from the numerical solutions of the corresponding Whitham systems and direct numerical simulations of the cKdV and cBO equations are compared with very good agreement obtained. In turn, DSWs obtained from direct numerical simulations of the KP and 2DBO equations are compared with the cKdV and cBO equations, again with good agreement. It is concluded that the (2+1) DSW behavior along self similar parabolic fronts can be effectively described by the DSW solutions of the reduced (1+1) dimensional equations.
Contributors:Omid Ahmadi, Hemin Koyi, Christopher Juhlin, Klaus Gessner
The Murchison domain forms the northwest part of the Youanmi Terrane, a tectonic unit within the Neoarchean Yilgarn Craton in Western Australia. In the Cue-Weld Range area the Murchison domain has experienced a complex magmatic and deformation history that resulted in a transposed array of greenstone belts that host significant iron, gold, and base metal deposits. In this study, we interpret the upper 2s (about 6km) of a deep crustal seismic profile 10GA–YU1, near the town of Cue, and correlate rock units and structures in outcrop with corresponding reflections. We performed 3D constant velocity ray-tracing and calculate the corresponding travel times for the reflections for time domain pre-stack and post-stack seismic data. This allows us to link shallow reflections with mafic volcanic rocks of the Glen Group and basaltic rocks of the Polelle Group in outcrop. Based on our interpretation and published geological maps and data, we propose a model in which the local stratigraphy represents a refolded thrust system. To test our hypothesis, we applied 2D acoustic finite difference forward modeling. The corresponding synthetic data were processed in the same way as the acquired data. Comparisons between the acquired and the synthetic data show that the model is consistent with observations. We propose a new model for the subsurface of the Cue-Weld Range area and argue that some of the lithologies in the area are repeated structurally at different levels. Our approach highlights the benefit of imaging and modeling of deep seismic transects to resolve local structural complexity in Archean granite-greenstone terrains.
This work develops the theory of the blow-up phenomena for one Sobolev initial–boundary value problem that arises in the theory of ion sound waves. This problem is considered with classical Neumann and nonclassical nonlocal boundary conditions. In both cases global unsolvability by using the method of test functions and local solvability by using the contracting mapping method are proved. The estimate of solvability time for classical solution is obtained. These estimations are used in numerical algorithm which allows us to specify the process of the solution's blow-up by using Richardson extrapolation. Some numerical experiments are presented in order to demonstrate the effectiveness of the proposed methods. The MATLAB code that realizes these numerical experiments is available.
Contributors:Juan Rodríguez-González, Magali I. Billen, Ana M. Negredo, Laurent G.J. Montesi
Subduction dynamics can be understood as the result of the balance between driving and resisting forces. Previous work has traditionally regarded gravitational slab pull and viscous mantle drag as the main driving and resistive forces for plate motion respectively. However, this paradigm fails to explain many of the observations in subduction zones. For example, subducting plate velocity varies significantly along-strike in many subduction zones and this variation is not correlated to the age of subducting lithosphere. Here we present three-dimensional and time-dependent numerical models of subduction. We show that along-strike variations of the overriding plate thermal structure can lead to along-strike variations in subducting plate velocity. In turn, velocity variations lead to significant migration of the Euler pole over time. Our results show that the subducting plate is slower beneath the colder portion of the overriding plate due to two related mechanisms. First, the mantle wedge beneath the colder portion of the overriding plate is more viscous, which increases mantle drag. Second, where the mantle wedge is more viscous, hydrodynamic suction increases, leading to a lower slab dip. Both factors contribute to decreasing subducting plate velocity in the region; therefore, if the overriding plate is not uniform, the resulting velocity varies significantly along-strike, which causes the Euler pole to migrate closer to the subducting plate. We present a new mechanism to explain observations of subducting plate velocity in the Cocos and Nazca plates. These results shed new light on the balance of forces that control subduction dynamics and prove that future studies should take into consideration the three-dimensional structure of the overriding plate.
Contributors:Csaba Jenei, Gábor Závodszky, György Paál, Balázs Tar, Zsolt Kőszegi
A retrospective modeling was performed in a case with restenosis after 6 months of a DES implantation to investigate the effect of the step-down at the distal edge of the stent on the wall shear stress (WSS) using 3D coronary angiography reconstruction and the intracoronary pressure traces during a cardiac cycle. The kinetics of the WSS was calculated through the cardiac cycle along the reconstructed vessel by fluid dynamic analysis. Contrary to the previous reports the greatest amplitude and average of the arterial WSS was detected where the restenosis developed later at the site of the step-down.