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We illustrate the potential of PDE-based traffic flow control in cardiovascular flow analysis, monitoring, and control, presenting a PDE-based control-oriented formulation, for 1-D blood flow dynamics in the presence of stenosis. This is achieved adopting an approach for modeling and analysis that relies on the potential correspondence of 1-D blood flow dynamics in the presence of stenosis, with 1-D traffic flow dynamics in the presence of bottleneck. We reveal such correspondence in relation to the respective (for the two flow types), speed dynamics and a (consistent with them) fundamental diagram-based reduction; bottleneck dynamic effects description and resulting boundary conditions; and free-flow/congested regimes characterization., Comment: Submitted to IEEE Transactions on Automatic Control on October 22, 2021

In this paper, we study a tumor growth model with nutrients. The model presents dynamic patch solutions due to the incompressibility of the tumor cells. We show that when the nutrients do not diffuse and the cells do not die, the tumor density exhibits regularizing dynamics thanks to an unexpected comparison principle. Using the comparison principle, we provide quantitative L 1 L^1 -contraction estimates and establish the C 1 , α C^{1,\alpha } -boundary regularity of the tumor patch. Furthermore, whenever the initial nutrient n 0 n_0 either lies entirely above or entirely below the critical value n 0 = 1 n_0=1 , we are able to give a complete characterization of the long-time behavior of the system. When n 0 n_0 is constant, we can even describe the dynamics of the full system in terms of some simpler nutrient-free and parameter-free model problems. These results are in sharp contrast to the observed behavior of the models either with nutrient diffusion or with death rate in tumor cells.

Melanoma is a fatal skin cancer that is curable and has dramatically increasing survival rate when diagnosed at early stages. Learning-based methods hold significant promise for the detection of melanoma from dermoscopic images. However, since melanoma is a rare disease, existing databases of skin lesions predominantly contain highly imbalanced numbers of benign versus malignant samples. In turn, this imbalance introduces substantial bias in classification models due to the statistical dominance of the majority class. To address this issue, we introduce a deep clustering approach based on the latent-space embedding of dermoscopic images. Clustering is achieved using a novel center-oriented margin-free triplet loss (COM-Triplet) enforced on image embeddings from a convolutional neural network backbone. The proposed method aims to form maximally-separated cluster centers as opposed to minimizing classification error, so it is less sensitive to class imbalance. To avoid the need for labeled data, we further propose to implement COM-Triplet based on pseudo-labels generated by a Gaussian mixture model. Comprehensive experiments show that deep clustering with COM-Triplet loss outperforms clustering with triplet loss, and competing classifiers in both supervised and unsupervised settings., Comment: 12 pages, 4 figures

Building on Pierre Simon's notion of distality, we introduce distality rank as a property of first-order theories and give examples for each rank $m$ such that $1\leq m \leq \omega$. For NIP theories, we show that distality rank is invariant under base change. We also define a generalization of type orthogonality called $m$-determinacy and show that theories of distality rank $m$ require certain products to be $m$-determined. Furthermore, for NIP theories, this behavior characterizes $m$-distality. If we narrow the scope to stable theories, we observe that $m$-distality can be characterized by the maximum cycle size found in the forking "geometry," so it coincides with $(m-1)$-triviality. On a broader scale, we see that $m$-distality is a strengthening of Saharon Shelah's notion of $m$-dependence., Comment: 32 pages

Magnetic resonance imaging (MRI) is increasingly used by the orbital surgeon to aid in the diagnosis, surgical planning, and monitoring of orbital disease. MRI provides superior soft tissue detail compared with computed tomography or ultrasound, and advancing techniques enhance its ability to highlight abnormal orbital pathology. Diffusion-weighted imaging is a specialized technique that uses water molecule diffusion patterns in tissue to generate contrast signals and can help distinguish malignant from benign lesions. Steady-state free precession sequences such as Constructive Interference in Steady-State (CISS) and Fast Imaging Employing Steady-state Acquisition (FIESTA) generate highly detailed, 3-dimensional reconstructed images and are particularly useful in distinguishing structures adjacent to cerebral spinal fluid. Magnetic resonance angiography can be used to characterize vascular lesions within the orbit. New developments in magnetic field strength as well as the use of orbital surface coils achieve increasingly improved imaging resolution.

We generalize a result of Lindenstrauss on the interplay between measurable and topological dynamics which shows that every separable ergodic measurably distal dynamical system has a minimal distal model. We show that such a model can, in fact, be chosen completely canonically. The construction is performed by going through the Furstenberg–Zimmer tower of a measurably distal system and showing that at each step there is a simple and canonical distal minimal model. This hinges on a new characterization of isometric extensions in topological dynamics.

Context Prostate-specific membrane antigen (PSMA) positron emission tomography/magnetic resonance imaging (PET/MRI) is a novel imaging technique with several potential applications in the prostate cancer (PCa) setting. Objective To perform a systematic review of the current evidence regarding the diagnostic performance of PSMA PET/MRI in patients with primary and recurrent PCa. Evidence acquisition A comprehensive bibliographic search on the MEDLINE and Cochrane Library databases was performed in October 2020. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Studies were deemed eligible if they assessed patients with primary or recurrent PCa (P) undergoing PSMA PET/MRI (I) with or without comparison with other imaging techniques (C) in order to evaluate its diagnostic performance (O). Retrospective and prospective primary clinical studies were included. Results of previous meta-analyses were reported. Evidence synthesis A total of 23 original articles and three meta-analyses were included. Limited evidence on PSMA PET/MRI is available, especially in the setting of partial gland ablation. PET/MRI can be an effective imaging modality for detecting primary PCa, showing higher accuracy than multiparametric MRI alone. It provides accurate local staging of primary PCa; however, there are contradictory results in this context when its performance is compared with other imaging techniques. PET/MRI also shows high performance for restaging and detecting tumor recurrence, even at low prostate-specific antigen levels. Conclusions PSMA PET/MRI could represent a valuable tool in the management of patients with primary and recurrent PCa. No specific recommendations can be provided. Patient summary Encouraging data regarding the benefits of prostate-specific membrane antigen positron emission tomography/magnetic resonance imaging in patients with prostate cancer are emerging from the literature.

Many complications in physiology are associated with a deviation in flow in arteries due to a stenosis. The presence of stenosis may transition the flow to weak turbulence. The degree of stenosis as well as its configuration whether symmetric or non-symmetric to the parent artery influences whether the flow would stay laminar or transition to turbulence. Plenty of research efforts focus on investigating the role of varying degrees of stenosis in the onset of turbulence under steady and pulsatile flow conditions. None of the studies, however, have focused on investigating this under oscillatory flow conditions as flow reversal is a major occurrence in a number of physiologic flows, and is of particular relevance in cerebrospinal fluid flow research. Following up on the previous work in which a $$75\%$$ 75 % stenosis was studied, this contribution is a detailed investigation of the role of degrees of stenosis on transition in an oscillatory flow. A cylindrical pipe with $$25\%$$ 25 % , $$50\%$$ 50 % and $$60\%$$ 60 % reductions in area in axisymmetric and eccentric configurations is studied for transition with 3 different pulsation frequencies of a purely oscillatory flow. Cycle averaged Reynolds numbers between 1800 and 2100 in steps of 100 are studied for each configuration resulting in 72 simulations each conducted on 76,800 CPU cores of a modern supercomputer. It is found that a higher degree of stenosis and eccentricity causes earlier transition to turbulence in oscillatory flow. The results further demonstrate that a higher frequency of oscillation results in larger hydrodynamic instability in the flow, which is more prominent in smaller degrees of stenosis.

A geodesic flower is a finite collection of geodesic loops based at the same point 𝑝 that satisfy the following balancing condition: the sum of all unit tangent vectors to all geodesic arcs meeting at 𝑝 is equal to the zero vector. In particular, a geodesic flower is a stationary geodesic net. We prove that, in every complete non-compact manifold with locally convex ends, there exists a non-trivial geodesic flower.

A flow-spine of a 3-manifold is a spine admitting a flow that is transverse to the spine, where the flow in the complement of the spine is diffeomorphic to a constant flow in an open ball. We say that a contact structure on a closed, connected, oriented 3-manifold is supported by a flow-spine if it has a contact form whose Reeb flow is a flow of the flow-spine. It is known by Thurston and Winkelnkemper that any open book decomposition of a closed oriented 3-manifold supports a contact structure. In this paper, we introduce a notion of positivity for flow-spines and prove that any positive flow-spine of a closed, connected, oriented 3-manifold supports a contact structure uniquely up to isotopy. The positivity condition is critical to the existence of the unique, supported contact structure, which is also proved in the paper., Comments: 38 pages and 25 figures. To be published in Annali di Matematica Pura ed Applicata (1923 -). This paper covers until Section 7 of the previous version arXiv:1912.05774v3 [math.GT]. The contents of the remaining sections will be covered in a separate paper

Mathematical modeling of a cancer treatment and drug delivery at the macroscale requires evaluating the leakage of solute flux into the targeted tumor or healthy tissue. This study provides a 2D model for the blood and nanoparticle transport in a single vessel surrounded by a tumor. In the vessel, the blood flow is described by Navier-Stokes equations which are coupled to advection–diffusion equation and energy equation for the fluid and nanoparticle transport. Impacts of the Brownian motion and thermophores parameters together with a thermal radiation are examined. Constant vascular fluid velocity across the vessel walls are assumed, and two phase nanofluid model is considered to represent the nanoparticle concentration. The solution methodology is depending on the finite volume method and features of the blood velocity, temperature and nanoparticle concentration are presented graphically. The major outcomes reveal that the blood temperature within the vessel is enhanced as the nanoparticle extravasation coefficient is increasing, while the concentration of the nanoparticles around the tumor is reduced.

The Updated Lagrangian method for nonlinear elasticity with contact is presented. First, we describe the Total Lagrangian for a compressible Neo-Hookean material. Next, we introduce the Updated Lagrangian formulation for Neo-Hookean and Ogden compressible materials with contact. An advantage of this approach is that at each iteration only a linear system is solved. The linear problem to be solved is written in the updated domain. Numerical results are presented: compression of a Hertz half ball and of a hyperelastic ring against a flat rigid foundation, and contact of an elastic cube and a ball.

Ensuring thermal stability is an important aspect of an arrester design process. In this paper, the thermal stability of station class surge arresters is investigated using a coupled electrothermal numerical model. An ungraded 550-kV-station class arrester model is successfully validated against temperature measurements in power grid operation. The arrester cooling rate is introduced to determine the thermal stability threshold. Thermally stable and unstable scenarios are compared. The influence of selected arrester design parameters on the stability threshold is analyzed. It is shown that an improved heat transfer in the arrester air gap increases the thermal stability threshold significantly. Additionally, the nonlinear zinc oxide material characteristics influence the thermal stability threshold strongly. Furthermore, a thermal stability prediction approach based on few, computationally less expensive simulations is proposed. Finally, the results are confirmed for an arrester model that is equipped with a field-grading system. The paper shows that the presented field simulation approach can be reliably used to determine the stability threshold of an arrester, thus, reducing the need for costly laboratory tests.

Quantitative magnetic resonance imaging is one of the few available methods for noninvasive diagnosis of degenerative changes in articular cartilage. The clinical use of the imaging data is limited by the lack of a clear association between structural changes at the molecular level and the measured magnetic relaxation times. In anisotropic, collagen-containing tissues, such as articular cartilage, the orientation dependency of nuclear magnetic relaxation can obscure the content of the images. Conversely, if the molecular origin of the phenomenon would be better understood, it would provide opportunities for diagnostics as well as treatment planning of degenerative changes in these tissues. We study the magnitude and orientation dependence of the nuclear magnetic relaxation due to dipole–dipole coupling of water protons in anisotropic, collagenous structures. The water–collagen interactions are modeled with molecular dynamics simulations of a small collagen-like peptide dissolved in water. We find that in the vicinity of the collagen-like peptide, the dipolar relaxation of water hydrogen nuclei is anisotropic, which can result in orientation-dependent relaxation times if the water remains close to the peptide. However, the orientation-dependency of the relaxation is different from the commonly observed magic-angle phenomenon in articular cartilage MRI.

The present paper concerns the formulation and the evolution of the non symmetrical growth of an avascular cancerous cell colony in an analytical mathematical fashion. Although most of the existing research considers spherical tumours, here we work in the frame of a more general case of the prolate spheroidal geometry. The tumour lies inside a host spheroidal shell which provides vital nutrients, receives the debris of the dead cells and also transmittes to the tumour the pressure imposed by the surrounding on its exterior boundary. Under the aim of studying the evolution of the exterior tumour boundary, we focus on the exterior conditions under which such a geometrical structure can be sustained. To that purpose, the corresponding nutrient concentration, the inhibitor concentration and the pressure field are calculated analytically providing the necessary data for the evolution equation to be solvable. It turns out that an avascular tumour can exhibit a prolate spheroidal growth only if the external conditions for the nutrient supply and the transversally isotropic pressure field have a specific form, which is consistent with the tumour evolution. Additionally, our model exhibits a geometrical reduction to special cases and, mainly, to the spherical geometry in order to recover the existing results for the sphere.

In this paper, we study with the definition of B-algebras, commutative B-algebras and fuzzy ideal in B-algebras. We consider the terminology of multipolar intuitionistic fuzzy ideal. We propose about multipolar intuitionistic fuzzy ideal in B-algebras and some related properties. Then, we discuss about theorems and propositions which contain some conditions for a multipolar intuitionistic fuzzy set become a multipolar intuitionistic fuzzy ideal in B-algebras.

In sport and training, it is necessary to continue monitoring the physiological parameters of athletes to ensure that they can maintain a high level of competition. The previous monitoring physiological status methods mainly are contactable by sensors that are worn on the body. This paper adopts a non-contact physiological parameter monitoring method by using imaging photoplethysmography (iPPG). In order to eliminate the noises in iPPG signals, the correlation energy entropy threshold adaptive denoising and variance characterization series are introduced to resist the noises from external conditions. The noises are removed by a threshold which is estimated by noise energy entropy. The constructed signals after denoising are used to estimate physiological parameters, such as heart rate and respiratory rate. The experimental results demonstrate that it estimates the physiological parameters better by using iPPG-based physiological parameter monitoring method than previous methods.

In proton therapy, a highly conformal proton dose can be delivered to the tumor by means of the steep distal dose penumbra at the end of the beam range. The proton beam range, however, is highly sensitive to range uncertainty, which makes accurately locating the proton range in the patient difficult. In-vivo range verification is a method to manage range uncertainty, one of the promising techniques being prompt gamma imaging (PGI). In earlier studies, we proposed gamma electron vertex imaging (GEVI), and constructed a proof-of-principle system. The system successfully demonstrated the GEVI imaging principle for therapeutic proton pencil beams without scanning, but showed some limitations under clinical conditions, particularly for pencil beam scanning proton therapy. In the present study, we upgraded the GEVI system in several aspects and tested the performance improvements such as for range-shift verification in the context of line scanning proton treatment. Specifically, the system showed better performance in obtaining accurate prompt gamma (PG) distributions in the clinical environment. Furthermore, high shift-detection sensitivity and accuracy were shown under various range-shift conditions using line scanning proton beams.

This article presents a stability analysis of fractional-order tumor system that correlates tumor-immune with chemotherapy under Lyapunov's theory. More particularly, a finite-time stabilization of prescribed system with the consequence of quantized input and actuator fault is investigated. Further, the nonlinear tumor system is converted to Takagi-Sugeno(T-S) fuzzy model. Then based on the utilization of Gronwall's inequality, the necessary and sufficient conditions are derived with the assist of Lyapunov's candidates. To overcome the effect of external disturbances such as unwanted smoke, intake habits and tower radiations, the optimal level of performance which is reduced from the generalized performance extended dissipative is included. Finally, a numerical simulation is presented with graphical results to expound the superiority and validity of the prescribed controller.

The bidomain model is the standard model for cardiac electrophysiology. In this paper, we investigate the instability and asymptotic behavior of planar fronts and planar pulses of the bidomain Allen-Cahn equation and the bidomain FitzHugh-Nagumo equation in two spatial dimension. In previous work, it was shown that planar fronts of the bidomain Allen-Cahn equation can become unstable in contrast to the classical Allen-Cahn equation. We find that, after the planar front is destabilized, a rotating zigzag front develops whose shape can be explained by simple geometric arguments using a suitable Frank diagram. We also show that the Hopf bifurcation through which the front becomes unstable can be either supercritical or subcritical, by demonstrating a parameter regime in which a stable planar front and zigzag front can coexist. In our computational studies of the bidomain FitzHugh-Nagumo pulse solution, we show that the pulses can also become unstable much like the bidomain Allen-Cahn fronts. However, unlike the bidomain Allen-Cahn case, the destabilized pulse does not necessarily develop into a zigzag pulse. For certain choice of parameters, the destabilized pulse can disintegrate entirely. These studies are made possible by the development of a numerical scheme that allows for the accurate computation of the bidomain equation in a two dimensional strip domain of infinite extent., Comment: 29 pages

In this paper, the variation of axial velocity of blood plasma with arterial radius has been studied in the laminar flow of blood plasma through a non-deformed artery. Since blood plasma is a Newtonian fluid, the Hagen-Poiseuille flow was used to study this variation. The Hagen-Poiseuille model was obtained by transforming the Navier- Stokes equations from rectangular coordinates system to cylindrical coordinates system and then making some approximations to the transformed equations. Furthermore, the axial velocity of blood plasma was plotted against the radius of a sampled artery, results and conclusions were made between the relationships.

Arrhythmias are potentially fatal disruptions to the normal heart rhythm, but their underlying dynamics is still poorly understood. Theoretical modeling is an important tool to fill this gap. Typical studies often employ detailed multidimensional conductance-based models. We describe the cardiac muscle with a three-dimensional map-based membrane potential model in lattices. Although maps retain the biophysical behavior of cells and generate computationally efficient tissue models, few studies have used them to understand cardiac dynamics. Our study captures healthy and pathological behaviors with fewer parameters and simpler equations than conductance models. We successfully generalize results obtained previously with reaction-diffusion systems, showing how chaotic properties result in reentry, a pathological propagation of stimuli that evolves to arrhythmias with complex spatiotemporal features. The bifurcation diagram of the single cell is very similar to that obtained in a detailed conductance-based model. We find torsade de pointes, a clinical manifestation of some types of tachycardia in the electrocardiogram, using a generic sampling of the whole network during spiral waves. We also find a novel type of dynamical pattern, with wavefronts composed of synchronized cardiac plateaus and bursts. Our study provides the first in-depth look at the use of map-based models to simulate complex cardiac dynamics., 15 pages, 9 figures. Eur. Phys. J. Spec. Top. (2022)

The risk of cardiovascular diseases is determined by the deposition of plaque in the coronary arteries. The areas of plaque deposition are also controlled by the flow dynamics and, for this, the topology of the arterial bifurcations has shown to be crucial. We present a detailed analysis of different topologies at the bifurcation based on numerical simulations of a mathematical model. Different diameters of the involved vessels as well as angle between them are analyzed. Unexpectedly, the curvature of the walls connecting the vessels is observed to play an important role.

In this work we analyse a PDE-ODE problem modelling the evolution of a Glioblastoma, which includes chemotaxis term directed to vasculature. First, we obtain some a priori estimates for the (possible) solutions of the model. In particular, under some conditions on the parameters, we obtain that the system does not develop blow-up at finite time. In addition, we design a fully discrete finite element scheme for the model which preserves some pointwise estimates of the continuous problem. Later, we make an adimensional study in order to reduce the number of parameters. Finally, we detect the main parameters determining different width of the ring formed by proliferative and necrotic cells and different regular/irregular behaviour of the tumor surface., Comment: 25 pages, 20 figures

In this work, using quasiconvexity and rank-one convexity conditions in Cosserat elasticity theory, we derive the Maxwell–Eshelby relation for Cosserat bodies with a surface of discontinuity.

Tensile testing of steel specimens under 'soft' and 'hard' loading conditions with simultaneous measurement of the self-magnetic field of the specimens using the metal magnetic memory (MMM) method is performed. By comparing the obtained tensile diagrams with magnetograms of the self-magnetic field variation, the relationship between the magnetic and mechanical characteristics at different stages of loading is determined. It is found that the self-magnetic field variation magnetograms of the specimens closely correspond to the true tensile diagrams. The ratios between the magnetic and mechanical characteristics, obtained during tensile testing of the specimens, allow for the determination of the limiting state of the metal at the time of crack formation using the measured magnetic parameters in stress concentration zones when performing practical diagnostics of equipment.

This paper proposes a novel differential kinematics of elastic tendons for tendon-driven manipulators where tendons transmit actuator force/torque to remote links via a train of pulleys. The local variability of tension and longitudinal speed in each tendon is carefully investigated in terms of the rest lengths of the virtually partitioned tendon segments along the tendon. A significant attention is paid to building a proper friction-tension mechanic model between the pulleys and tendons to identify the no-slip points that are important to be used as kinematic constraints. The kinematic relations of tendon are obtained for two possible types of tendon-pulley transmission, i.e., free-free ended and fixed-free ended types, and then a complete kinematics of tendon is formulated by augmenting all the kinematic relations existing in the entire system. Simulation and experimental results are provided to validate the proposed kinematics of tendon by comparing with a previous simple spring model where the tension was determined by the relative positions of consecutive pulleys.

A Nystrom method for linear second kind Volterra integral equations on unbounded intervals, with sufficiently smooth kernels, is described. The procedure is based on the use of a truncated Lagrange interpolation process and of a truncated Gaussian quadrature formula. The stability and the convergence of the method in suitable weighted spaces of functions are studied and some numerical examples showing its reliability are presented. In particular, the proposed method has been tested for the numerical resolution of some Volterra integral equations arising from the reformulation of differential models describing metastatic tumor growth whose unknown solutions represent biological observables as the metastatic mass or the number of metastases.

The growth and remodelling of soft tissues plays a significant role in many physiological applications, particularly in understanding and managing many diseases. A commonly used approach for soft tissue growth and remodelling is volumetric growth theory, introduced in the framework of finite elasticity. In such an approach, the total deformation gradient tensor is decomposed so that the elastic and growth tensors can be studied separately. A critical element in this approach is to determine the growth tensor and its evolution with time. Most existing volumetric growth theories define the growth tensor in the reference (natural) configuration, which does not reflect the continuous adaptation processes of soft tissues under the current configuration. In a few studies where growth from a loaded configuration was considered, simplifying assumptions, such as compatible deformation or geometric symmetries, were introduced. In this work, we propose a new volumetric growth law that depends on fields evaluated in the current configuration, which is residually stressed and loaded, without any geometrical restrictions. We illustrate our idea using a simplified left ventricle model, which admits inhomogeneous growth in the current configuration. We compare the residual stress distribution of our approach with the traditional volumetric growth theory, that assumes growth occurring from the natural reference configuration. We show that the proposed framework leads to qualitative agreements with experimental measurements. Furthermore, using a cylindrical model, we find an incompatibility index that explains the differences between the two approaches in more depth. We also demonstrate that results from both approaches reach the same steady solution published previously at the limit of a saturated growth. Although we used a left ventricle model as an example, our theory is applicable in modelling the volumetric growth of general soft tissues.

The red blood cell particle is important in the research studies of blood flow and drug delivery. The biconcave shape makes the motions of the red blood cell particle in fluids more complex than sphere or ellipsoid. Sedimentation behaviors of a red blood cell particle in long circular tubes are investigated by using the lattice Boltzmann method with the Galilean-invariant momentum exchange method. Different blockage ratios and the particle to fluid density ratios are considered. One periodic and two steady sedimentation modes are discovered. When the blockage ratio rises, the motion mode of particles changed from horizontal mode to inclined mode. With the increase of the particle to fluid density ratio, the sedimentation mode changed from the inclined mode to the horizontal mode, and the time of the particles reaching the stable state is obviously distinct in different sedimentation modes. Surprisingly, the oscillatory mode is observed in the larger blockage ratio and lower density ratio of particle to fluid. These works may be able to make active promotions to the research studies of blood circulation of humans.

We show that finitely generated Cox rings are Gorenstein. This leads to a refined characterization of varieties of Fano type: they are exactly those projective varieties with Gorenstein canonical quasicone Cox ring. We then show that for varieties of Fano type and Kawamata log terminal quasicones, iteration of Cox rings is finite with factorial master Cox ring. Moreover, we prove a relative version of Cox ring iteration for almost principal solvable $G$-bundles., 16 pages, minor changes, Corollary 1 added

In this study, 65 kinds of wood samples were classified by using artificial neural networks based on the measured value of wood thermal physical parameters. First, the thermal conductivities and the thermal diffusion coefficients of the wood samples were measured. The transient temperature rise curve of wood samples during the test process was recorded, and the characteristic values of the transient temperature rise curve were extracted by logarithmic curve fitting. The emissivity spectrum representing the thermal physical properties of wood surface was measured, and the characteristic spectral data were selected according to the principal component analysis. An artificial neural network model was established based on the extracted feature values and characteristic spectral data to classify the wood species. The experimental results showed that the comprehensive correct classification rate of the proposed wood classification method was 99.85%. In addition, the proposed wood classification method was compared with a wood classification method based on laser induced breakdown spectrum and near infrared spectrum, which indicates the feasibility of wood classification based on the values of wood thermal physical properties.

Cancer is the leading cause of death globally, with 90% of deaths being caused by cancer metastasis. Circulating tumor cells (CTCs) play an important role in early diagnosis of cancer metastasis and in monitoring of therapeutic response. Therefore, reliable methods to isolate, collect and culture CTCs are required to obtain information on metastasis status and therapeutic treatment. In this work, we present a CTC-processing system: acoustic bubble for spheroid trapping, rotation, and culture: a tumor-on-a-chip platform (ABSTRACT). The platform consists of a main channel, several parallel sub-microchannels with microcavities and culture chambers. The microcavity is designed to trap a bubble with desired shape at the entrance of the sub-microchannel. Under the acoustic actuation, the trapped bubble oscillates and creates a secondary radiation force to trap and rotate CTCs at a desired location. By controlling the acoustic bubble, CTCs can be continuously trapped from the blood flow, rotated to form a spheroid, and released to the microchamber for culture. We systematically investigated the effects of device geometry, flow parameters, and input voltage on trapping of CTCs to optimize the performance. Additionally, the successful on-chip spheroid culture demonstrates the biocompatibility and the simplicity of this platform. Besides simplifying conventional complex CTC processing procedures, this ABSTRACT platform also shows great potential for downstream analysis of tumor cells, such as monitoring the progression of metastasis and personalized drug testing.

Using optical coherence tomography, the scattering coefficients of collagen bundles are estimated at different levels of tissue hydration. We test the validity of a simple theoretical model of dehydration changes in the optical characteristics of a collagen bundle, which is considered as a system of parallel cylinders that model the collagen fibrils forming the bundle. The characteristics of scattering by individual scatterers are calculated using the Mie theory. To take into account the cooperative effects caused by the close packing of the scatterers, use is made of the standard packing function for a system of identical cylinders. The theoretical model also relies on a certain empirical law of changes in the hydration level of fibrils with a change in the water content in the tissue, which predetermines changes in the diameter and refractive index of fibrils during dehydration and rehydration of the tissue. It is shown that the theoretical estimates obtained using this model are in good agreement with the experimental data, which makes it possible to consider this model as reliable.

This article reviews 3D porous biomass-derived carbon materials as microwave absorbers, including their biomass sources, the transformation from biomass to porous carbon, and their corresponding microwave absorption applications and mechanism.

Flow spinning is an advantageous technology in forming thin-walled cylindrical parts, but for cylindrical parts with inner ribs,the height of the inner ribs that can be formed is limited. Aimed at the problem that the inner ribs are difficult to fill in such components, a numerical simulation model of staggered spinning of thin-walled cylindrical parts with cross inner ribs is established based on Abaqus, and the influence of the number of rollers on the filling of inner ribs is analyzed. The process test of the cylinder part with orthogonal inner ribs is conducted. The results show that in the staggered spinning process, increasing the number of rollers will reduce the diameter expansion of the aluminum alloy cylindrical part with inner ribs, and inhibit the axial flow of materials, leading to a higher geometric accuracy of the inner ribs. The comparison of the simulation results and the test results shows that the average error of the inner rib filling fullness of simulation result is 11.3%, and the simulation model has a good reliability.

Cylindrical specimens are commonly used in Split Hopkinson pressure bar (SHPB) tests to study the uniaxial dynamic properties of concrete-like materials. In recent years, true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact loads. For such tests, cubic specimens are needed. It is well understood that static material strength obtained from cylinder and cube specimens are different. Conversion factors are obtained and adopted in some guidelines to convert the material strength obtained from the two types of specimens. Previous uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ones. However, the mechanical background of these findings is unclear. As an extension of the previous laboratory study, this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical model. The stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical specimens. The detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain rates. For cubic specimen, the corners are more severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical specimens. These results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate dependent. Based on the simulation results, an empirical formula of conversion factor as a function of strain rate is proposed, which supplements the traditional conversion factor for quasi-static material strength. It can be used for transforming the dynamic compressive strength from cylinders to cubes obtained from impact tests at different strain rates.

The main purpose of this paper is to examine what kind of information the smooth Riemannian map defined between two Riemannian manifolds provides about the character of the Riemannian map when a horizontal hyperelastic curve on the total manifold is carried to a hyperelastic curve on the base manifold. For the solution of the mentioned problem, firstly, the behavior of an arbitrary horizontal curve on the total manifold under a Riemannian map is investigated and the equations related to pullback connection are obtained. The necessary conditions are given for the Riemannian map to be h-isotropic or totally umbilical when a horizontal Frenet curve in the total manifold transforms to a hyperelastic curve on the base manifold. Then, the concept of the h-hyperelastic Riemannian map is defined and using these findings, the Riemannian map along horizontal hyperelastic curves is characterized., Scientific and Technological Research Council of Turkey (TUBITAK) [119F025], This paper is supported by the Scientific and Technological Research Council of Turkey (TUBITAK) with the number 119F025.

We have calculated the radiological parameters such as computerized tomography (CT) numbers effective atomic number (Zeff) and electron density (Nel) of newborn tissue and adult tissue of lung, kidney, heart and brain. Effective atomic number is computed by calculating the molecular, atomic and electronic cross section in the wide energy range of 1 keV–100 keV using WinXCOM. The new born tissue and adult tissue a very similar, but their atomic number, CT number and electron densities differs. This fact helps in the radiography and radiotherapy.

According to the Warburg effect, there are some significant differences between metabolisms, products and process of respirations of cancer cells and normal cells. For example, normal cells absorb oxygen and glucose and give water molecules, carbon dioxide, ATP molecules and some number of spinors; while cancer cells take glucose and give lactate, less number of ATP molecules and different number of spinors. Using this property, we can design a system from two graphene sheets that are connected by pairing the fourth free electrons of carbons. Then, we can break some pairs and produce some holes. The number of these holes should be equal to the number of radiated spinors by normal cells. Near a normal cell, all holes are filled and the graphene system doesn't emit any electrical current or wave. However, near a cancer cell, some extra holes or spinors remain that their motions produce some electrical currents. These currents force on cancer cell membranes and destroy them and consequently, cause the cell death. Also, these currents emit some electromagnetic waves which detectors could take them out of the human's body and consequently, they could play the main role in imaging.

This paper introduces a novel concept of the pulsed neutron facility (PNF) for maximizing the production of the thermal neutrons and its application to medical use based on prompt gamma neutron activation analysis (PGNAA) using Monte Carlo simulations. The PNF consists of a compact D-T neutron generator, a graphite pile, and a detection system using Cadmium telluride (CdTe) detector arrays. The configuration of fuel pins in the graphite monolith and the design and materials for the moderating layer were studied to optimize the thermal neutron yields. Biological samples – normal and cancerous breast tissues – including chlorine, a trace element, were used to investigate the sensitivity of the characteristic γ-rays by neutron-trace material interactions and the detector responses of multiple particles. Around 90 % of neutrons emitted from a deuterium-tritium (D-T) neutron generator thermalized as they passed through the graphite stockpile. The thermal neutrons captured the chlorines in the samples, then the characteristic γ-rays with specific energy levels of 6.12, 7.80 and 8.58 MeV were emitted. Since the concentration of chlorine in the cancerous tissue is twice that in the normal tissue, the count ratio of the characteristic γ-rays of the cancerous tissue over the normal tissue is approximately 2.

A tumor-immune system with diffusion and delays is proposed in this paper. First, we investigate the impact of delay on the stability of nonnegative equilibrium for the model with a single delay, and the system undergoes Hopf bifurcation when delay passes through some critical values. We obtain the normal form of Hopf bifurcation by applying the multiple time scales method for determining the stability and direction of bifurcating periodic solutions. Then, we study the tumor-immune model with two delays, and show the conditions under which the nontrivial equilibria are locally asymptotically stable. Thus, we can restrain the diffusion of tumor cells by controlling the time delay associated with the time of tumor cell proliferation and the time of immune cells recognizing tumor cells. Finally, numerical simulations are presented to illustrate our analytic results.

Based on the impact damper, a dynamic model of a non-fixed constrained collision system was established. The coefficient of restitution is used as the main control parameter to analyze the system’s periodic movement and its bifurcation region. The chattering movement characteristics of the system were revealed. The interval of restitution coefficient for the chattering of collision system under various mass ratio and frequency ratio was obtained. The results show that the chattering phenomenon occurs in the collision system when the coefficient of restitution is greater than 0.5; as the mass ratio decreases, the interval of restitution coefficient for chattering continues to expand; as the frequency increases, the interval of restitution coefficient for chattering narrows.

Oral inhalation of aerosolized drugs has be widely applied in healing the affected body organs including lesions of the throat and lungs and it is more efficient than those conventional therapies, such as intravenous drip, intramuscular injection and external topical administration in the aspects of the dosage reduction and side effects of drugs. Nevertheless, the traditional atomization devices always exhibit many drawbacks. For example, non-uniformed atomization particle distribution, the instability of transient atomization quantity and difficulties in precise energy control would seriously restrict an extensive use of atomization inhalation therapy. In this study, the principle of intra-hole fluctuation phenomenon occurred in the hole is fully explained, and the produced volume change is also estimated. Additionally, the mathematical expression of the atomization rate of the atomizing device is well established. The mechanism of the micro-pump is further clarified, and the influence of the vibration characteristics of the atomizing film on the atomization behavior is analyzed theoretically. The curves of sweep frequency against the velocity and amplitude of the piezoelectric vibrator are obtained by the Doppler laser vibrometer, and the corresponding mode shapes of the resonance point are achieved. The influence of vibration characteristics on atomization rate, atomization height and atomization particle size are also verified by experiments, respectively. Both the experimental results and theoretical calculation are expected to provide a guidance for the design of this kind of atomization device in the future.

Knots are natural, inevitable structures in wood left by branches. Most of the negative mechanical effects of knots are caused by strain concentration effects and fiber variability. In this study, digital image correlation (DIC) was used to observe the global strain distribution around intergrown knots, encased knots, knotholes, and artificial holes in thin Japanese cedar (Cryptomeria japonica) tangential plates of different sizes subjected to tensile load. The results indicated that the strain around knots is more homogeneous than that around holes, and that the influence of wood anatomy is greater than that of the geometric factors of a hole. Knots have naturally optimized structures for branch junctions, altering wood properties, such as grain angle, microfibril angle, and branch collar, to disperse strain and prevent fractures. The fractures caused by four types of knots or holes differed. The specimens with artificial holes were the most consistent with strain concentration theory, but none of the specimens within the other three natural knots or holes exhibited fractures around knots. Although the strain peak of natural knots occurred at knot edges, this was unrelated to the fractures. Finally, the strain characteristics of the knot tissue revealed that the internal structure of intergrown knots was completely connected with surrounding tissues, meaning that they can deform synchronously with the specimen. By contrast, encased knots tissue exhibited an extremely low modulus in the transverse direction of the specimens (tangent axis of wood) because the strain was higher in the knot tissue than in the surrounding wood.

Dynamic polymer networks utilize weak bonding interactions to dissipate the stored energy and provide a source of self-healing for the material. Due to this, tracking the progression of damage in t...

Background: Today, the most common method for kidney stone therapy is extracorporeal shock wave lithotripsy. Current research is a numerical simulation of kidney stone fragmentation via ultrasonic shock waves. Most numerical studies in lithotripsy have been carried out using the elasticity or energy method and neglected the dissipation phenomenon. In the current study, it is solved by not only the linear acoustics equation, but also the Westervelt acoustics equation which nonlinearity and dissipation are involved. Objective: This study is to compare two methods for simulation of shock wave lithotripsy, clarifying the effect of shock wave profiles and stones’ material, and investigating side effects on surrounding tissues.Material and Methods: Computational study is done using COMSOL Multiphysics, commercial software based on the finite element method. Nonlinear governing equations of acoustics, elasticity and bioheat-transfer are coupled and solved. Results: A decrease in the rise time of shock wave leads to increase the produced acoustic pressure and enlarge focus region. The shock wave damages kidney tissues in both linear and nonlinear simulation but the damage due to high temperature is very negligible compared to the High Intensity Focused Ultrasound (HIFU). Conclusion: Disaffiliation of wave nonlinearity causes a high incompatibility with reality. Stone’s material is an important factor, affecting the fragmentation.

Organ and tissue growth result from an integration of biophysical communication across biological scales, both in time and space. In this review, we highlight new insight into the dynamic connections between control mechanisms operating at different length scales. First, we consider how the dynamics of chemical and electrical signaling in the shape of gradients or waves affect spatiotemporal signal interpretation. Then, we discuss the mechanics underlying dynamic cell behavior during oriented tissue growth, followed by the connections between signaling at the tissue and organismal levels.

Due to the irregular surface of zebrafish larvae and the difficulty of fixing the body, there are high requirements for its injection target point and posture control. By establishing a zebrafish data set containing key points and three-dimensional posture annotations, a network model for zebrafish key point recognition is designed using convolutional neural networks. The posture angle information is further calculated through three-dimensional coordinate transformation. Experiments demonstrate that this method can obtain a more accurate zebrafish posture angle under the condition of posture change. In response to this method, an operating platform that can fix zebrafish juveniles and precisely adjust their posture is designed to lay the foundation for subsequent experimental operations.

Tendon-driven soft wearable robots should be simple, compact, and safe because they are worn on the human body and interacts directly with the human. Here, unlike rigid robots, wire pretension should be removed at the end-effector due to the inherent characteristics of the soft robot. In this paper, for the stable and compact actuation system without pretension, a linear actuator named Slider-Tendon Linear Actuator is proposed. The proposed actuator is designed to make a linear motion using a tendon rather than other linear transmissions such as ball screw or lead screw transmission. By using the proposed design method that uses the tendon, the actuator size was reduced to 23.6% of the size of an actuator using a ball screw because the tendon can endure high tensile force with a small cross-section area. Furthermore, this paper proposes a robot design methodology to locate the robot mechanism in the actuator, rather than in the end-effector. The proposed actuator is designed to contain fast-connection and stroke amplified under-actuation mechanism. With this method, not only is the complexity and size of the worn part reduced but also its performance is improved. Finally, by applying this actuator to a specific wearable robot, this paper verifies that the proposed actuator sufficiently satisfies the wearable robot requirements.