Although the environment in which termites live is very heterogeneous, most experimental studies on the termite tunnel patterns have been conducted on homogeneous sand substrates. In order to explore how the heterogeneity affects tunnel patterns, I developed an agent-based model to simulate termite tunneling behavior at the individual level. In this model, grid space consists of easy and difficult areas for tunneling. Heterogeneity, H, was defined as the degree of the mixture of the two areas.

The matrix equation Xp+A？XA=Q has been studied to find the positive definite solution in several researches. In this paper, we consider fixed-point iteration and Newton's method for finding the matrix p-th root. From these two considerations, we will use the Newton-Schulz algorithm (N.S.A). We will show the residual relation and the local convergence of the fixed-point iteration. The local convergence guarantees the convergence of N.S.A. We also show numerical experiments and easily check that the N.S. algorithm reduce the CPU-time significantly.

The cellular dispersion and therapeutic control of glioblastoma, the most aggressive type of primary brain cancer, depends critically on the migration patterns after surgery and intracellular responses of the individual cancer cells in response to external biochemical cues in the microenvironment. Recent studies have shown that miR-451 regulates downstream molecules including AMPK/CAB39/MARK and mTOR to determine the balance between rapid proliferation and invasion in response to metabolic stress in the harsh tumor microenvironment.

In this paper, a mathematical model of contractile ring-driven cytokinesis is presented by using both phase-field and immersed-boundary methods in a three-dimensional domain. It is one of the powerful hypotheses that cytokinesis happens driven by the contractile ring; however, there are only few mathematical models following the hypothesis, to the author’s knowledge. I consider a hybrid method to model the phenomenon. First, a cell membrane is represented by a zero-contour of a phase-field implicitly because of its topological change. Otherwise, immersed-boundary particles represent a contractile ring explicitly based on the author’s previous work. Here, the multi-component (or vector-valued) phase-field equation is considered to avoid the emerging of each cell membrane right after their divisions. Using a convex splitting scheme, the governing equation of the phase-field method has unique solvability.

Ultrasound diagnosis is routinely used in obstetrics and gynecology for fetal biometry, and owing to its time-consuming process, there has been a great demand for automatic estimation. However, the automated analysis of ultrasound images is complicated because they are patient specific, operator dependent, andmachine specific.

Magnetic resonance electrical impedance tomography (MREIT) is a high-resolution conductivity imaging method utilizing measured magnetic flux density data induced by externally injected currents. Most MREIT image reconstructionmethods including the harmonic Bz algorithm adopt iterative schemes to handle the non-linear relation between conductivity and magnetic flux density. Iterative methods, however, may not guarantee a reliable conductivity reconstruction when the measured magnetic flux density data are contaminated with a significant amount of noise. In this paper, we propose a new image reconstruction method which alleviates the technical difficulties of the iterative harmonic Bz algorithm. It effectively reduces the number of iterations by two at most. To improve the image quality, it incorporates the influence of non-transversal current densities.

We study on the reconstruction of 3D left ventricle(LV) using only 2D echocardiography data and information on apical long-axis views. Especially, this paper focuses on determining the 3D position of LV contours extracted from 2D echocardiography images. First we mathematically model the relationship between LV contours on the apical views and their corresponding 3D positions. The relationship is expressed as a linear equation in which the right-hand side is the measured data consisting of all the LV contour points on each view and the coefficient matrix is an unknown matrix that transforms the unknown 3D positions into contour points on their related apical view, with distance and orthogonality conditions on the coefficient matrix and the 3D positions. Next we consider a non-convex constrained minimization problem to determine the coefficient matrix and the 3D positions.

To achieve source authentication, message integrity, and non-repudiation, a number of authen-tication protocols adopt several types of digital signatures: public-key signatures, identity-based signatures, and certicateless signatures. In this paper, we show that an anonymous remote authentication scheme for wireless body area network, an anonymous handover authentication scheme, an authentication scheme for emergency mobile cyber-physical system, and an authenticated key agreement protocol based on the three types of signatures schemes are insecure against various impersonation attacks due to insecurity of the underlying signature schemes. These results showthat using cryptographic primitives without security proofs causes serious security vulnerabilities on the security protocol itself. Our results give strong evidences that the security of adopted cryptographic primitives should be proved in appropriate formal security models as well as proof of the security protocol itself.

In this paper, we investigate the security of Rainbow and Unbalanced Oil-and-Vinegar (UOV) signature schemes based on multivariate quadratic equations, which is one of the most promising alternatives for post-quantum signature schemes, against side-channel attacks. We describe correlation power analysis (CPA) on the schemes that yield full secret key recoveries. First, we identify a secret leakage of secret affine maps S and T during matrix-vector products in signing when Rainbow is implemented with equivalent keys rather than random affine maps for optimal implementations. In this case, the simple structure of the equivalent keys leads to the retrieval of the entire secret affine map T. Next, we extend the full secret key recovery to the general case using random affine maps via a hybrid attack: after recovering S by performing CPA, we recover T by mounting algebraic key recovery attacks. We demonstrate how this leakage on Rainbow can be practically exploited on an 8-bit AVR microcont

The Unbalanced Oil and Vinegar signature scheme (UOV) is one of multivariate quadratic public key cryptosystems and remains unbroken. In Inscrypt 2015, Tan and Tang proposed variants of UOV, Matrix-based UOV, to reduce the size of the secret key and generate signature faster. We show that Matrix-based UOV is entirely broken by finding equivalent keys in polynomial-time. In practice, we can forge Matrix-based UOV signature at 80 and 100 security levels in less than 0.37 seconds and 0.53 seconds, respectively.