arXiv subjects

Masako Bando

Publications and source records attributed to Masako Bando.

At least 19 recordsLinked to original sources

arXiv2015

Dose and dose-rate dependence of mutation frequency under long-term exposure - A new look at DDREF from WAM model -

We investigate the dose and dose-rate dependence of the mutation frequency caused by artificial radiations with Whack-A-Mole (WAM) model which we have recently proposed. In particular, we pay special attention to the case of long-term and low dose-rate exposure. The results indicate that the dose-rate dependence is successfully described with WAM model and it may replace the so-called DDREF, the concept of which has long been adopted to take account of the difference between the high dose-rate data and the low dose-rate ones. Basic properties of WAM model are discussed emphasizing the dose-rate dependence to demonstrate how the explicit dose-rate dependence built in the model plays a key role. By adopting the parameters that are determined to fit the mega mouse experiments, biological effects of long-term exposure to extremely low dose-rate radiation are discussed. In WAM model, the effects of the long-term exposure show a saturation property, which makes a clear distinction from the LNT hypothesis which predicts a linear increase of the effects with time.

physics.bio-ph↗

arXiv2014

Whack-A-Mole Model: Towards unified description of biological effect caused by radiation-exposure

We present a novel model to estimate biological effects caused by artificial radiation exposure, Whack-a-mole (WAM) model. It is important to take account of the recovery effects during the time course of the cellular reactions. The inclusion of the dose-rate dependence is essential in the risk estimation of low dose radiation, while nearly all the existing theoretical models relies on the total dose dependence only. By analyzing the experimental data of the relation between the radiation dose and the induced mutation frequency of 5 organisms, mouse, drosophila, chrysanthemum, maize and tradescantia, we found that all the data can be reproduced by WAM model. Most remarkably, a scaling function, which is derived from WAM model, consistently accounts for the observed mutation frequencies of 5 organisms. This is the first rationale to account for the dose rate dependence as well as to give a unified understanding of a general feature of organisms.

physics.bio-ph↗

arXiv2014

Reaction Rate Theory of Radiation Exposure and Scaling Hypothesis in Mutation Frequency

We develop a kinetic reaction model for cells having irradiated DNA molecules due to ionizing radiation exposure. Our theory simultaneously accounts for the time-dependent reactions of the DNA damage, the DNA mutation, the DNA repair, and the proliferation and apoptosis of cells in a tissue with a minimal set of model parameters. In contrast to existing theories for radiation exposition, we do not assume the relationships between the total dose and the induced mutation frequency. Our theory provides a universal scaling function that reasonably explains the mega-mouse experiments in Ref.[W. L. Russell and E. M. Kelly, Proc. Natl. Acad. Sci. USA. {\bf 79} (1982) 542.] with different dose rates. Furthermore, we have estimated the effective dose rate, which is biologically equivalent to the ionizing effects other than those caused by artificial irradiation. This value is $ 1.11 \times 10^{-3} ~\rm{[Gy/hr]}$, which is significantly larger than the effect caused by natural background radiation.

physics.bio-ph↗

arXiv2013

The Legacy of Hideki Yukawa, Sin-itiro Tomonaga, and Shoichi Sakata: Some Aspects from their Archives

Hideki Yukawa, Sin-itiro Tomonaga and Shoichi Sakata pioneered nuclear and particle physics and left enduring legacies. Their friendly collaboration and severe competition laid the foundation to bring up the active postwar generation of nuclear and particle physicists in Japan. In this presentation we illustrate milestones of nuclear and particle physics in Japan from 1930's to mid-1940's which have been clarified in Yukawa Hall Archival Library, Tomonaga Memorial Room and Sakata Memorial Archival Library.

physics.hist-ph↗

arXiv2013

Radiation Exposure Theory Comparison of data on Mutation Frequencies of Mice

We propose Radiation Exposure Theory (RET), a mathematical framework to estimate biological damage caused by irradiation. This is an extension of LDM model which was proposed in the paper [Y. Manabe et al.: J. Phys. Soc. Jpn. 81, 104004(2012)]. The theory is based on physical protocol, 'a stimulus and its response'. It takes account of considerable response including mutation, cell death caused by outer stimulus, as well as biological functions such as proliferation, apoptosis and repair. By taking account of biological issues, namely a variety of preventable effects, which is characteristic feature of living object. RET can explain various data which simple LNT does not reproduce. As one of the characteristic features of RET, we propose a scaling law, namely all the data point with different dose rate irradiation are predicted to lie on the universal line if the variables, the biological damage function as a function of time development after artificial irradiation starts are converted to renormalized ones. The above scaling law can be compared with experimental data. We adopt the accumulated experiments performed by so-called mega mouse projects. It is found that their data points are converted into a universal scaling function and are in reasonably agreement with the prediction of RET.

physics.bio-ph↗

arXiv2013

Comparison of data on Mutation Frequencies of Mice Caused by Radiation - Low Dose Model -

We propose LD(Low Dose) model, the extension of LDM model which was proposed in the previous paper [Y. Manabe et al.: J. Phys. Soc. Jpn. 81 (2012) 104004] to estimate biological damage caused by irradiation. LD model takes account of all the considerable effects including cell death effect as well as proliferation, apoptosis, repair. As a typical example of estimation, we apply LD model to the experiment of mutation frequency on the responses induced by the exposure to low levels of ionizing radiation. The most famous and extensive experiments are those summarized by Russell and Kelly [Russell, W. L. & Kelly, E. M: Proc. Natl Acad. Sci. USA 79 (1982) 539-541], which are known as 'Mega-mouse project'. This provides us with important information of the frequencies of transmitted specific-locus mutations induced in mouse spermatogonia stem-cells. It is found that the numerical results of the mutation frequency of mice are in reasonable agreement with the experimental data: the LD model reproduces the total dose and dose rate dependence of data reasonably. In order to see such dose-rate dependence more explicitly, we introduce the dose-rate effectiveness factor (DREF). This represents a sort of preventable effects such as repair, apoptosis and death of broken cells, which are to be competitive with proliferation effect of broken cells induced by irradiation.

physics.bio-ph↗

arXiv2012

A Mathematical Model for Estimating Biological Damage Caused by Radiation

We propose a mathematical model for estimating biological damage caused by low-dose irradiation. We understand that the Linear Non Threshold (LNT) hypothesis is realized only in the case of no recovery effects. In order to treat the realistic living objects, our model takes into account various types of recovery as well as proliferation mechanism, which may change the resultant damage, especially for the case of lower dose rate irradiation. It turns out that the lower the radiation dose rate, the safer the irradiated system of living object (which is called symbolically "tissue" hereafter) can have chances to survive, which can reproduce the so-called dose and dose-rate effectiveness factor (DDREF).

physics.bio-ph↗

arXiv2008

Business Cycle and Conserved Quantity in Economics

We propose a dynamical model for business cycle based on an optimal DI model. In the model there exists a conserved quantity, which corresponds to the total energy in a dynamical system. We found that the business cycle with the period 6 or 7 years is nicely reproduced, since the model predicts a periodic motion in the conservative system.

q-fin.GN↗

arXiv2007

An Exotic Approach to Hadron Physics

An exotic approach to hadrons is discussed. It is based on the recently developed open-closed string duality explicitly conjectured as the AdS/CFT correspondence. Mesons as well as pentaquarks are studied in this approach. Spins are introduced as distribution functions over the string, and a second quantization method of string theory is examined and used to estimate the mass and decay width of various hadrons. This approach provides a way to understand the structure of flavor by a configuration of probe branes.

hep-ph↗

arXiv2006

Can symmetric texture reproduce unitarity triangle and $m_b/m_τ$ ?

We study the SUSY SO(10) GUT with the symmetric two-zero textures of quark/lepton mass matrix which realize the Georgei-Jarlskog relations in down-type quark and charged lepton masses. We show that the important constraints to such framework come from the bottom-tau unification and the observed value of $\sin2β$, one of the angles in the CKM unitarity triangle. We investigate the symmetric two-zero textures assumed at the GUT scale by solving the MSSM renormalization group equations with right-handed neutrino threshold effects. As a result, the value of $\tan\tildeβ$ is constrained to be large enough and the representation of Higgs field which couples to the third generation of left- and right-handed neutrinos is restricted by the bottom-tau unification condition. The textures with vanishing 1-2 (and 2-1) element for up-type quarks and vanishing 1-3 (and 3-1) element for down-type quarks are favored by the observation of $\sin2β$.

hep-ph↗

arXiv2006

Meson Strings and Flavor Branes

In a QCD-like string model based on D6 flavor branes in the presence of D4 color branes wrapping one of the compactified dimension on an $S^1$, the shape of meson strings in the five dimensional curved space as well as the potential between quark and anti-quark are investigated. The flavor branes on which both ends of a meson string live are assumed to be separated in this five dimensional space, depending on the values of the constituent quark masses. It is shown in this picture that the meson string with different flavors on both ends changes its shape at a critical distance. There is, however, no critical distance for the meson with the same flavors. At this critical distance the potential between quark and anti-quark with different flavors gives a point of reflection and changes its shape around this point. Accordingly, the attractive force between quark and anti-quark seems to become stronger when the distance of flavor branes connecting meson strings becomes larger. This indicates quark systems with different flavors can form high-density states.

hep-ph↗

arXiv2004

Symmetric Mass Matrix with Two Zeros in SUSY SO(10) GUT, Lepton Flavor Violations and Leptogenesis

We study the symmetric 2-zero texture of the neutrino mass matrix, which is obtained from the symmetric Dirac neutrino mass matrix with 2-zeros and right-handed Majorana neutrino mass matrix with the general form via the see-saw mechanism, for the SUSY SO(10) GUT model including the Pati-Salam symmetry. We show that the only one texture in our model, having degenerate mass spectrum for the 1st and 2nd generation of right-handed Majorana neutrino, can simultaneously explain the current neutrino experimental data, lepton flavor violating processes and baryon asymmetry of the Universe. Within such a framework, the predicted values of the light and heavy Majorana neutrino masses, together with $|U_{e3}|$, $J_{\rm CP}$ and $|< M_{ee} >|$, are almost uniquely determined.

hep-ph↗

arXiv2004

Pentaquark Baryons in String Theory

The recently observed pentaquark baryons $\Theta^{+}$ and $\Xi^{--}$ are studied in the dual gravity theory of QCD. By developing a general formulation useful for studying the branched string web in a curved space, simple mass formulae of the pentaquark baryons are derived in the Maldacena prototype model for supersymmetric QCD and a more realistic model for ordinary QCD. Even though the approximations adopted here in deriving these formulae are extremely naive, the predicted values of the masses do not differ significantly from their experimental values. We thus conclude that this approach is promising for the purpose of obtaining a description of the observed masses of pentaquarks and of their extremely narrow decay widths. With the aim of constructing more reliable mass formulae, a preliminary sketch is given of how spin, the hyperfine interaction and parity are considered in the string picture.

hep-ph↗

arXiv2003

Can Symmetric Texture reproduce Neutrino Bi-large Mixing?

We study the symmetric texture of geometric form with 2-zeros to see if it is consistent with the presently-known neutrino masses and mixings. In the neutrino mass matrix elements we obtain numerically the allowed region of the parameters including CP violating phases, which can reproduce the present neutrino experiment data. The result of this analysis dictates the narrow region for the GUT model including Pati-Salam symmetry with texture zeros to be consistent with the experimental data. The $|U_{e3}|$ and $J_{CP}$ are also predicted in such models.

hep-ph↗

arXiv2003

Implications of Bi-Large Neutrino Mixing on GUTs

Under the assumptions that 1) the quark/lepton mass matrices take Froggatt-Nielsen's factorized power form λ^{ψ_i+ψ_j} with anomalous U(1) charges ψ_i, and 2) the U(1) charges ψ_i respect the SU(5) GUT structure, we show that the quark mass data and the mass-squared difference ratio of solar and atmospheric neutrinos, as inputs, necessarily imply that both the 1-2 and 2-3 mixings in the MNS matrix U_{MNS} are large. This analysis also gives a prediction that U_{e3}\equiv (U_{MNS})_{13} is of order λ\sim (0.1 - 0.5). We also add an argument that E_6 GUT is favored.

hep-ph↗

arXiv2003

Neutrino Bi-Large Mixings and Family

After a brief review of quark-lepton relations in grand unified theories (GUT), we show that the Pati-Salam relation with only one type of Higgs field configuration with "four zero symmetric texture" can reproduce two large neutrino mixings as well as observed mass differences. This is quite in contrast to the case of SU(5) where bi-large mixings essentially come from the charged lepton sector with non-symmetric charged lepton mass matrix.

hep-ph↗

arXiv2003

Neutrino Mass Matrix in Terms of Up-Quark Masses

We demonstrate that under the "symmetric zero texture" with minimal Majorana mass matrix, neutrino masses and mixing angles are expressed in terms of up-quark masses, $m_t,m_c,m_u$. This provides interesting relations among neutrino mixing angles and up-type quark masses. Especially we predict $|U_{e3}| \leq 0.11$ even if we include the small mixing effects coming from charged lepton side. Also absolute masses of three neutrinos are predicted almost uniquely. This is quite in contrast to the case where bi-large mixings come from the charged lepton sector with non-symmetric charged lepton mass matrix.

hep-ph↗

arXiv2003

Neutrino Mass Matrix Predicted From Symmetric Texture

Within the framework of grand unified theories, we make full analysis of symmetric texture to see if such texture can reproduce large neutrino mixings, which have recently been confirmed by the observed solar and atmospheric neutrino oscillation experiments. It is found that so-called symmetric texture with anomalous U(1) family symmetry with Froggatt-Nielsen mechanism does not provide a natural explanation of two large mixing angles. On the contrary we should adopt "zero texture" which have been extensively studied by many authors and only this scenario can reproduce two large mixing angles naturally. Under such "zero texture" with minimal symmetric Majorana matrix, all the neutrino masses and mixing angles, 6 quantities, are expressed in terms of up-quark masses, $m_t,m_c,m_u$ with two adjustable parameters. This provides interesting relations among neutrio mixing angles, $\tan^2 2θ_{12} \simeq \frac{144m_c}{m_t} \tan^2 2θ_{23} \cos^2 θ_{23}, \quad \sin^2 θ_{13} \simeq \frac{4m_c}{m_t}\sin^2 θ_{23} \cos^2 θ_{12}$. Thus $|U_{e3}|$ is predicted to lie within the range $0.01-0.06$. Also absolute masses of three neutrinos are predicted almost uniquely. This is quite in contrast to the case where bi-large mixings come from the charged lepton sector with non-symmetric mass matrix, which does not provide the information of neutrino masses.

hep-ph↗