1 
研究論文（学術雑誌）

共著

Sudden spreading of infections in an epidemic model with a finite seed fraction

Takehisa Hasegawa, Koji Nemoto

The European Physical Journal B


91

2018/03/29


10.1140/epjb/e2018803433



2 

共著

Efficiency of prompt quarantine measures on a susceptibleinfectedremoved model in networks

Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society (APS)

96/ 2

2017/08/11

24700045

10.1103/PhysRevE.96.022311

URL


3 

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Local clustersize statistics in the critical phase of bond percolation on the Cayley tree

Tomoaki Nogawa, Takehisa Hasegawa, Koji Nemoto

Journal of Statistical Mechanics: Theory and Experiment



2016/05/11


10.1088/17425468/2016/05/053202



4 

共著

Outbreaks in susceptibleinfectedremoved epidemics with multiple seeds

Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society (APS)

93/ 3

2016/03/31

24700045

10.1103/PhysRevE.93.032324

URL

We study a susceptibleinfectedremoved (SIR) model with multiple seeds on a regular random graph. Many researchers have studied the epidemic threshold of epidemic models above which a global outbreak can occur, starting from an infinitesimal fraction of seeds. However, there have been few studies of epidemic models with finite fractions of seeds. The aim of this paper is to clarify what happens in phase transitions in such cases. The SIR model in networks exhibits two percolation transitions. We derive the percolation transition points for the SIR model with multiple seeds to show that as the infection rate increases epidemic clusters generated from each seed percolate before a single seed can induce a global outbreak.

5 

共著

Advantage or disadvantage of migration in a preypredator system

Kazunori Sato, Takehisa Hasegawa, Satoru Morita, Jin Yoshimura, Keiichi Tainaka

Far East Journal of Applied Mathematics



2015





6 

共著

Discontinuous transition of a multistage independent cascade model on networks

Takehisa Hasegawa, Koji Nemoto

Journal of Statistical Mechanics: Theory and Experiment



2014/11/14


10.1088/17425468/2014/11/P11024



7 

共著

Critical Phase in Complex Networks: a Numerical Study

Takehisa Hasegawa, Tomoaki Nogawa, Koji Nemoto

Discontinuity, Nonlinearity, and Complexity



2014/10/01


10.5890/DNC.2014.09.008



8 

共著

Suppressing epidemics on networks by exploiting observer nodes

Taro Takaguchi, Takehisa Hasegawa, Yuichi Yoshida

Physical Review E



2014/07/11


10.1103/PhysRevE.90.012807



9 

共著

Transitiontype change between an inverted BerezinskiiKosterlitzThouless transition and an abrupt transition in bond percolation on a random hierarchical smallworld network

Tomoaki Nogawa, Takehisa Hasegawa

Physical Review E



2014/04/07


10.1103/PhysRevE.89.042803



10 

共著

Hierarchical scalefree network is fragile against random failure

Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society

88/ 6, 6280710628075

2013/12/06

15393755

10.1103/PhysRevE.88.062807

URL

We investigate site percolation in a hierarchical scalefree network known as the DorogovtsevGoltsevMendes network. We use the generating function method to show that the percolation threshold is 1, i.e., the system is not in the percolating phase when the occupation probability is less than 1. The present result is contrasted to bond percolation in the same network of which the percolation threshold is zero. We also show that the percolation threshold of intentional attacks is 1. Our results suggest that this hierarchical scalefree network is very fragile against both random failure and intentional attacks. Such a structural defect is common in many hierarchical network models.

11 

共著

Profile and scaling of the fractal exponent of percolations in complex networks

Takehisa Hasegawa, Tomoaki Nogawa, Koji Nemoto

EPL



2013/11/06


10.1209/02955075/104/16006



12 

共著

Observability transitions in correlated networks

Takehisa Hasegawa, Taro Takaguchi, Naoki Masuda

Physical Review E



2013/10/14


10.1103/PhysRevE.88.042809



13 

共著

Absence of the nonpercolating phase for percolation on the nonplanar Hanoi network

Takehisa Hasegawa, Tomoaki Nogawa

Physical Review E



2013/03/18


10.1103/PhysRevE.87.032810



14 

共著

Criticality governed by the stable renormalization fixed point of the Ising model in the hierarchical smallworld network

Nogawa Tomoaki, Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society

86/ 3

2012/09

15393755

10.1103/PhysRevE.86.030102

URL

We study the Ising model in a hierarchical smallworld network by renormalization group analysis and find a phase transition between an ordered phase and a critical phase, which is driven by the coupling strength of the shortcut edges. Unlike ordinary phase transitions, which are related to unstable renormalization fixed points (FPs), the singularity in the ordered phase of the present model is governed by the FP that coincides with the stable FP of the ordered phase. The weak stability of the FP yields peculiar criticalities, including logarithmic behavior. On the other hand, the critical phase is related to a nontrivial FP, which depends on the coupling strength and is continuously connected to the ordered FP at the transition point. We show that this continuity indicates the existence of a finite correlationlengthlike quantity inside the critical phase, which diverges upon approaching the transition point.

15 

共著

Robustness of correlated networks against propagating attacks

Takehisa Hasegawa, Keita Konno, Koji Nemoto

The European Physical Journal B  Condensed Matter And Complex Systems



2012/07/30


10.1140/epjb/e2012302900



16 

共著

Generalized Scaling Theory for Critical Phenomena Including Essential Singularities and Infinite Dimensionality

Nogawa Tomoaki, Hasegawa Takehisa, Nemoto Koji

Physical Review Letters

American Physical Society

108/ 25

2012/06/22

00319007

10.1103/PhysRevLett.108.255703

URL

We propose a generic scaling theory for critical phenomena that includes powerlaw and essential singularities in finite and infinite dimensional systems. In addition, we clarify its validity by analyzing the Potts model in a simple hierarchical network, where a saddlenode bifurcation of the renormalizationgroup fixed point governs the essential singularity.

17 

共著

Phase transition without global ordering in a hierarchical scalefree network

Hasegawa Takehisa, Sato Masataka, Nemoto Koji

Physical Review E

American Physical Society

85/ 1

2012/01

15393755

10.1103/PhysRevE.85.017101

URL

We study the sitebond percolation on a hierarchical scalefree network, namely, the decorated (2,2)flower, by using the renormalization group technique. The phase diagram essentially depends on the fraction of occupied sites. Surprisingly, when each site is unoccupied even with a small probability, the system permits neither the percolating phase nor the nonpercolating phase, but rather only critical phases. Although the order parameter always remains zero, a transition still exists between the critical phases that is characterized by the value of the fractal exponent, which measures the degree of criticality; the system changes from one critical state to another with the jump of the fractal exponent at the transition point. The phase boundary depends on the fraction of occupied sites. When the fraction of unoccupied sites exceeds a certain value, the transition line between the critical phases disappears, and a unique critical phase remains.

18 

単著

An Introduction to Complex Networks

HASEGAWA Takehisa

Interdisciplinary Information Sciences

The Editorial Committee of the Interdisciplinary Information Sciences

17/ 3, 175195

2011

13409050

10.4036/iis.2011.175

URL

GSIS SELECTED LECTURES: Exploring Collaborative Mathematics

19 

共著

Robustness of networks against propagating attacks under vaccination strategies

Takehisa Hasegawa, Naoki Masuda

Journal of Statistical Mechanics: Theory and Experiment



2011/09/20


10.1088/17425468/2011/09/P09014



20 

共著

Numerical study of a threestate hostparasite system on the square lattice

Takehisa Hasegawa, Norio Konno, Naoki Masuda

Physical Review E



2011/04/06


10.1103/PhysRevE.83.046102



21 

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Generatingfunction approach for bond percolations in hierarchical networks

Takehisa Hasegawa, Masataka Sato, Koji Nemoto

Physical Review E



2010/10/01


10.1103/PhysRevE.82.046101



22 

共著

Critical phase of bond percolation on growing networks

Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society

81/ 5

2010/05

15393755

10.1103/PhysRevE.81.051105

URL

The critical phase of bond percolation on the random growing tree is examined. It is shown that the root cluster grows with the system size N as Nψ and the mean number of clusters with size s per node follows a power function ns ∝ s(τ) in the whole range of open bond probability p. The exponent τ and the fractal exponent ψ are also derived as a function of p and the degree exponent γ and are found to satisfy the scaling relation τ=1 + ψ^[1]. Numerical results with several network sizes are quite well fitted by a finitesize scaling for a wide range of p and γ, which gives a clear evidence for the existence of a critical phase.

23 

共著

Reply to the comment on 'Monte Carlo simulation study of the twostage percolation transition in enhanced binary trees'

Tomoaki Nogawa, Takehisa Hasegawa

Journal of Physics A: Mathematical and Theoretical



2009/11/04


10.1088/17518113/42/47/478002



24 

共著

Ferromagnetic Ising spin systems on the growing random tree

Hasegawa Takehisa, Nemoto Koji

Physical Review E

American Physical Society

80/ 2

2009/08

15393755

10.1103/PhysRevE.80.026126

URL

We analyze the ferromagnetic Ising model on a scalefree tree; the growing random tree model with the linear attachment kernel A_k=k+α. We derive an estimate of the divergent temperature T_s below which the zerofield susceptibility of the system diverges. Our result shows that T_s is related to α as tanh(J/T_s)=α/[2(α+1)], where J is the ferromagnetic interaction. An analysis of exactly solvable limit for the model and numerical calculation supports the validity of this estimate.

25 

共著

MonteCarlo simulation study of the twostage percolation transition in enhanced binary tree

Tomoaki Nogawa, Takehisa Hasegawa

Journal of Physics A: Mathematical and Theoretical



2009/03/16


10.1088/17518113/42/14/145001



26 

共著

Susceptibility of the Ising model on the scale free network with a Cayley treelike structure

Takehisa Hasegawa, Koji Nemoto

Physica A: Statistical mechanics and its applications



2007/10/22


10.1016/j.physa.2007.10.041



27 

共著

Ising model on the scalefree network with a Cayleytreelike structure

Takehisa Hasegawa, Koji Nemoto

Physical Review E



2007/02/21


10.1103/PhysRevE.75.026105



28 

共著

Real Space Renormalization Group Analysis with the Replica Method for the Two Dimensional Ising Edwards–Anderson Model

Hasegawa Takehisa, Nemoto Koji

Journal of the Physical Society of Japan

THE PHYSICAL SOCIETY OF JAPAN

75/ 7

2006/06/26

00319015

10.1143/JPSJ.75.074701

URL

We apply the real space renormalization group (RG) to the replica Hamiltonian of the two dimensional Ising Edwards–Anderson model to discuss the existence of the spin glass (SG) phase. We derive the RG equations under the replica symmetric (RS) ansatz and the resulting flow diagram indicates the existence of the SG phase. The critical exponent for the SG transition has a plausible value while that of the multicritical point (MCP) is a complex number. We consider that this failure at the MCP is due to not taking the RS breaking into account. Indeed we find that the RS breaking parameter is relevant both at the SG critical point and the MCP, indicating the nontriviality of the SG phase of this model.
