arXiv subjects

Takahiro Miura

Publications and source records attributed to Takahiro Miura.

18 recordsLinked to original sources

arXiv2024

WhisperMask: A Noise Suppressive Mask-Type Microphone for Whisper Speech

Whispering is a common privacy-preserving technique in voice-based interactions, but its effectiveness is limited in noisy environments. In conventional hardware- and software-based noise reduction approaches, isolating whispered speech from ambient noise and other speech sounds remains a challenge. We thus propose WhisperMask, a mask-type microphone featuring a large diaphragm with low sensitivity, making the wearer's voice significantly louder than the background noise. We evaluated WhisperMask using three key metrics: signal-to-noise ratio, quality of recorded voices, and speech recognition rate. Across all metrics, WhisperMask consistently outperformed traditional noise-suppressing microphones and software-based solutions. Notably, WhisperMask showed a 30% higher recognition accuracy for whispered speech recorded in an environment with 80 dB background noise compared with the pin microphone and earbuds. Furthermore, while a denoiser decreased the whispered speech recognition rate of these two microphones by approximately 20% at 30-60 dB noise, WhisperMask maintained a high performance even without denoising, surpassing the other microphones' performances by a significant margin.WhisperMask's design renders the wearer's voice as the dominant input and effectively suppresses background noise without relying on signal processing. This device allows for reliable voice interactions, such as phone calls and voice commands, in a wide range of noisy real-world scenarios while preserving user privacy.

cs.HC↗

arXiv2024

Mid-career pitfall of consecutive success in science

The creativity of scientists often manifests as localized hot streaks of significant success. Understanding the underlying mechanisms of these influential phases can enhance the effectiveness of support systems and funding allocation, fostering groundbreaking discoveries worthy of accolades. Historically, analyses have suggested that hot streaks occur randomly over time. However, our research, through meticulous examination, reveals that these phases are not flatly distributed but are more frequent at the early and late stages of scientists' careers. Notably, both early and late hot streaks are marked by dense tie collaborations, with the former typically involving close partnerships with particular authors and the latter being characterized by involvement in large-scale projects compared with single-top or ordinary papers. This pattern indicates that mid-career researchers lack both intimate relations and resources to keep big projects, leading to``mid-career pitfal'' of consecutive success. This insight holds profound implications for the development of policies and initiatives aimed at bolstering innovative research and discovery.

cs.SI↗

arXiv2022

Simulation of Lindblad equations for quarkonium in the quark-gluon plasma

We study the properties of the Lindbladian quantum mechanical evolution of quarkonia with non-Abelian charges (color-singlet and octet) in the quark-gluon plasma. We confirm that heavy quark recoils in the Lindblad equation correctly thermalize quarkonium colorful states within statistical errors from the simulation method. We also demonstrate that the Lindblad equation in the dipole limit can provide an efficient alternative method, which is applicable to a finite time evolution before thermalization and dramatically reduces the numerical cost. Our findings will serve as a foundation for large-scale simulation of quarkonium dynamics in the relativistic heavy-ion collisions.

nucl-th↗

arXiv2022

Storyteller: The papers co-citing Sleeping Beauty and Prince before awakening

In the Cumulative Advantage(CA) model, which is one of the most fundamental approaches to understand the mechanism of citation dynamics, papers receive citations depending on how much they have been already cited. On the other hand, a substantial effect not included in CA is that some surprising discoveries suddenly acquire citations after a long time from publishing. This phenomenon is known as Sleeping Beauty(SB). Since disrupting discoveries need long-time discussion by the research community to accept, SBs can capture innovative findings and reveal the nature of disruptive scientific knowledge production. To research SBs citation burst mechanism, bibliometricians consider the existence of the Prince(PR) for each SBs, which can be the trigger of SBs awakeness. For example, the discovery of Green Fluorescent Protein(GFP), which got Nobel prize in chemistry, had been overlooked for 30 years until Chalfie and Tsien, who also received the prize, developed a method to use GFP as a marker protein in genetic engineering. However, how does Chalfies and Tsiens research relight the hidden knowledge in the research community? If we can clarify such a mechanism rediscovering from nearly nothing, it can be helpful in science support and policy decision-making. This study proposes a Storyteller that focuses on the connection between SB and PR before SB gets citation burst by co-citation. PR is found to be the paper awakening SB in retrospect, but it is not easy to detect it as the trigger of SBs awakeness at the time of PR submission. We named the papers which co-cites SB and PR before the citation burst of SB as Storyteller(ST) and analyze (1) how ST contributes to broadening the novelty of SB&PR connections and (2) how much ST leads the citation burst after awakening.

cs.DL↗

arXiv2021

Nonequilibrium evolution of quarkonium in medium

We review recent progress in open quantum system approach to the description of quarkonium in the quark-gluon plasma. A particular emphasis is put on the Lindblad equations for quarkonium and its numerical simulations.

hep-ph↗

arXiv2020

Trace preserving quantum dynamics using a novel reparametrization-neutral summation-by-parts difference operator

We develop a novel numerical scheme for the simulation of dissipative quantum dynamics following from two-body Lindblad master equations. All defining continuum properties of the Lindblad dynamics, hermiticity, positivity and in particular trace conservation of the evolved density matrix are preserved. The central ingredient is a new spatial difference operator, which not only fulfils the summation by parts (SBP) property but also implements a continuum reparametrization property. Using the time evolution of a heavy-quark anti-quark bound state in a hot thermal medium as an explicit example, we show how the reparametrization neutral summation-by-parts (RN-SBP) operator preserves the continuum properties of the theory.

physics.comp-ph↗

arXiv2019

Quantum Brownian motion of a heavy quark pair in the quark-gluon plasma

In this paper we study the real-time evolution of heavy quarkonium in the quark-gluon plasma (QGP) on the basis of the open quantum systems approach. In particular, we shed light on how quantum dissipation affects the dynamics of the relative motion of the quarkonium state over time. To this end we present a novel non-equilibrium master equation for the relative motion of quarkonium in a medium, starting from Lindblad operators derived systematically from quantum field theory. In order to implement the corresponding dynamics, we deploy the well established quantum state diffusion method. In turn we reveal how the full quantum evolution can be cast in the form of a stochastic non-linear Schrödinger equation. This for the first time provides a direct link from quantum chromodynamics (QCD) to phenomenological models based on non-linear Schrödinger equations. Proof of principle simulations in one-dimension show that dissipative effects indeed allow the relative motion of the constituent quarks in a quarkonium at rest to thermalize. Dissipation turns out to be relevant already at early times well within the QGP lifetime in relativistic heavy ion collisions.

nucl-th↗

arXiv2003

The renormalization group effect to the bi-maximal mixing

We discuss whether the bi-maximal mixing given at GUT is consistent with the solar mixing at the normal side at the low energy. We consider the radiative corrections due to the tau-Yukawa, the neutrino-Yukawa and the slepton threshold corrections and discuss in what situation the maximal solar angle rotates towards the normal side. In this scheme, the |V_{13}| and the Dirac CP phase delta are induced radiatively and we estimate these values.

hep-ph↗

arXiv2002

Prediction of |V_{13}| and the Dirac phase in the Neutrino Mixing Matrix

We considered a model where |V_{13}|=0 so that delta=0 at M_R and analyzed mixing angles and CP violation angles at the low energy scale by using the renormalization group in the MSSM model. In this model, parameters at M_R scale are two mixing angles (theta_{12} and theta_{23}), three neutrino masses, and two Majorana phases. We found that (1) sin^2 2 theta_{12} at the low energy scale must be less than that at $M_R$ scale, (2) the induced |V_{13}| can be as large as 0.05 if masses of neutrinos are around 0.05 eV.

hep-ph↗

arXiv2002

Effects of charged Higgs boson and QCD corrections in $\bar B \to D τ\barν_τ$

We study effects of charged Higgs boson exchange in $\bar B \to D τ\barν_τ$. The Yukawa couplings of Model II of two-Higgs-doublet model, which has the same Yukawa couplings as MSSM, is considered. We evaluate the decay rate including next-to-leading QCD corrections and estimate uncertainties in the theoretical calculation. Our analysis will contribute to probe an extended Higgs sector at B factory experiments.

hep-ph↗

arXiv2002

Exploring the neutrino mass matrix at M_R scale

We discuss the neutrino mass matrix which predicts zero or small values of |V_{13}| in MSSM and found the inequality, sin^2 2theta_{12} <= sin^2 2theta_sol, where sin^2 2theta_{12} is the mixing angle at M_R scale and sin^2 2theta_{sol} is the value determined by the solar neutrino oscillation. This constraint says that the model which predicts a larger value of tan^2 theta_{sol} at M_R than the experimental value is excluded. In particular, the bi-maximal mixing scheme at M_R scale is excluded, from the experimental value tan^2 theta_sol<1. In this model, |V_{13}| and a Dirac phase at m_Z are induced radiatively and turn out to be not small. The effective neutrino mass is expected to be of order 0.05 eV.

hep-ph↗

arXiv2001

The matter fluctuation effect to T violation at a neutrino factory

We derived an analytic formula for T violation by using the perturbation theory for small quantities, $Δm_{21}^2L/2E$ and $δa(x)L/2E$, where $δa(x)$ represents symmetric and asymmetric matter fluctuations, i.e., deviations from the average density. We analyzed the effect of matter fluctuations to T violation, by assuming PREM profile of earth matter density. We found that matter fluctuations do not give any viable contribution for $L<$6000km, while the fluctuation effect becomes large due to resonances for $L>$7000km. For 7000km$ $8000km, the contribution from matter fluctuations becomes large but contributes constructively.

hep-ph↗

arXiv2001

The matter effect to T-violation at a neutrino factory

We analyzed T-violation in neutrino oscillation by using perturbation methods with respect to $Δm_{21}^2L/2E$ and $δa(x)L/2E$, where $δa(x)$ represents the matter density fluctuation from its average value. We found that the matter contribution to T-violation arises from interferences between $Δm_{21}^2L/2E$ and $δa(x) L/2E$. In the 2nd order, the symmetric and asymmetric matter density fluctuations give effects to the $\sin δ$ (intrinsic) and the $\cos δ$ (fake) parts of T-violation. We give their analytic forms and analyze the matter contribution to the $\sin δ$ and $\cos δ$ terms. We found that, for L=3000km, both the symmetric and asymmetric matter density fluctuations give negligible contributions to T-violation, and that thus the constant (average) matter density gives a good approximation. On the other hand, we argue that, for L=7000km or longer length, T-violation turns out to become very small due to cancellation between the 1st and the 2nd order terms. This shows that the constant (average) matter approximation is not valid.

hep-ph↗

arXiv2000

Renormalization group effect and a democratic-type neutrino mass matrix

In our previous paper, we proposed the democratic-type neutrino mass matrix which gives interesting predictions, $θ_{23}=-\fracπ4$, $|\tan θ_{12}|=\sqrt{2-3\sin^2 θ_{13}}$ and $δ=\frac π2$, where $θ_{ij}$ is the mixing angle between mass eigenstates $ν_i$ and $ν_j$, and $δ$ is the CP violation angle in the standard parameterization of mixing matrix. In this paper, we examined how predictions behave at $m_Z$ by assuming that they are given at the right-handed neutrino mass scale, $M_R$.

hep-ph↗

arXiv2000

Quantum effects for the neutrino mixing matrix in the democratic-type model

We investigate the quantum effects for the democratic-type neutrino mass matrix given at the right-handed neutrino mass scale $m_R$ in order to see (i) whether $θ_{23}=-π/4$ predicted by the model is stable to explain the atmospheric neutrino anomaly, (ii) how $θ_{12}$ and $θ_{13}$ behave, and (iii) whether the predicted Dirac CP phase $δ$ keeps maximal size, at the weak scale $m_Z$. We find that, for the (inversely) hierarchical mass spectrum with $m_1\sim m_2$, $θ_{23}$ and $θ_{13}$ are stable, while $θ_{12}$ is not so, which leads to the possibility that the solar neutrino mixing angle can become large at $m_Z$ even if it is taken small at $m_R$. We also show that $δ$ keeps almost maximal for the above mass spectrum, and our model can give the large CP violation effect in the future neutrino oscillation experiments if the solar neutrino puzzle is explained by the large mixing angle MSW solution.

hep-ph↗

arXiv2000

Democratic-type neutrino mass matrix

We consider the democratic-type neutrino mass matrix and show that this matrix predicts the atmospheric neutrino mixing to be almost maximal, $\sin^2 2θ_{atm}>0.999$ as well as the large CP violation (the CP violation phase in the standard form is maximal $δ=π/2$). We construct the $Z_3$ symmetric dimension five effective Lagrangian with two up-type Higgs doublets and show that this Lagrangian leads to the democratic neutrino mass matrix. Furthermore, we consider the restricted model with one up-type Higgs doublet and obtain the prediction, $0.87<\sin^2 2θ_{sol}<8/9$.

hep-ph↗

arXiv2000

Large CP Violation, Large Mixings of Neutrinos and the $Z_3$ Symmetry

We present neutrino mass matrices which predict the atmospheric neutrino mixing to be almost maximal, $\sin^2 2θ_{atm}>0.999$, as well as the large solar neutrino mixing, $8/9>\sin^2 2θ_{sol}>0.87$, and the large CP violation (the CP violation phase in the standard form is maximal $δ=π/2$), based on the $Z_3$ symmetry.

hep-ph↗

arXiv1999

Large CP Violation, Large Mixings of Neutrinos and Democratic-type Neutrino Mass Matrix

We propose a democratic-type neutrino mass matrix based on $Z_3$ symmetry. This mass matrix predicts the CP violation phase, $δ=π/2$, and the mixing angle between the mass eigenstates $ν_2$ and $ν_3$, $\sin^2 θ_{23}= \cos^2 θ_{23}=1/2$ which is essential for the large atmospheric neutrino mixing, between $ν_μ$ and $ν_τ$. In this model, the large CP violation effect may be expected.

hep-ph↗