Search

Your search keyword '"Yamada, Tomohiro"' showing total 1,025 results
Start Over Author "Yamada, Tomohiro"
1,025 results on '"Yamada, Tomohiro"'

1. Determining all biunitary triperfect numbers of a certain form

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, 11A05, 11A25
Abstract

We shall show that $2160$ is the only biunitary triperfect number divisible by $27=3^3$., Comment: 11 pages. arXiv admin note: text overlap with arXiv:1705.00189

Published
2024

2. Beam dynamics study of the high-power electron beam irradiator using niobium-tin superconducting cavity

Author

Tanaka, Olga, Honda, Yosuke, Yamamoto, Masahiro, Yamada, Tomohiro, and Sakai, Hiroshi

Subjects
Physics - Accelerator Physics
Abstract

A compact accelerator design for irradiation purposes is being proposed at KEK. This design targets an energy of 10 MeV and a current of 50 mA. Current design includes a 100 kV thermionic DC electron gun with an RF grid, 1-cell normal-conducting buncher cavity, and Nb$_{3}$Sn superconducting cavities to accelerate the beam to the final energy of 10 MeV. The goal of the present beam dynamics study is the beam loss suppression (to the ppm level), since it results in a thermal load on the cavity. Then the beam performance at the accelerator exit should be confirmed. The main issue was to transport the beam without loss, since the initial electron energy (100 keV) is low, and the beam parameters are intricately correlated. In addition, the space charge effect is considerable. For this reason, simultaneous optimization of multiple parameters was necessary. Here we report optimization results and their effect on the design of the machine.

Published
2024

3. On Gauss-Kraitchik formula for cyclotomic polynomials via symmetric functions

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11B83, Secondary 05A19, 05E05, 11C08, 11R09, 11R18, 11T22, 12E05
Abstract

We give explicit upper bounds for coefficients of polynomials appearing in Gauss-Kra\"{i}tchik formula for cyclotomic polynomials. We use a certain relation between elementary symmetric polynomials and power sums polynomials., Comment: 10 pages, minor revisions (L^1-norm definition and (28))

Published
2024

4. On a theorem of Kanold on odd perfect numbers

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11A25, Secondary 11A05
Abstract

We shall prove that if $N=p^\alpha q_1^{2\beta_1} q_2^{2\beta_2} \cdots q_{r-1}^{2\beta_{r-1}}$ is an odd perfect number such that $p, q_1, \ldots, q_{r-1}$ are distinct primes, $p\equiv\alpha\equiv 1\mod{4}$ and $t$ divides $2\beta_i+1$ for all $i=1, 2, \ldots, r-1$, then $t^5$ divides $N$, improving an eighty-year old result of Kanold., Comment: 8 pages, the author's final version of the paper of the same title in Indian J. Pure Appl. Math, which is available at https://doi.org/10.1007/s13226-023-00530-y

Published
2023
Full Text
View/download PDF

5. Explicit improvements of the Brun-Titchmarsh theorem for arbitrary intervals

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11N36, Secondary 11B83, 11N05, 11N13
Abstract

We give an explicit version of Brun-Titchmarsh theorem applicable for arbitrary moduli and arbitrary intervals. For example, we show that $\pi(x+y; k, a)-\pi(x; k, a)<2y/(\varphi(k)(\log (y/k)+0.8601))$ for any relatively prime positive integers $k$ and $a$ and any positive real numbers $x$ and $y$ such that $y>k$., Comment: 14 pages

Published
2023

7. Impact of malnutrition on mortality and neurological recovery of older patients with spinal cord injury

Author

Tamai, Koji, Terai, Hidetomi, Nakamura, Hiroaki, Yokogawa, Noriaki, Sasagawa, Takeshi, Nakashima, Hiroaki, Segi, Naoki, Ito, Sadayuki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Watanabe, Kota, Yamane, Junichi, Takeda, Kazuki, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Kuroda, Akiyoshi, Inoue, Gen, Kakutani, Kenichiro, Kakiuchi, Yuji, Kiyasu, Katsuhito, Tominaga, Hiroyuki, Tokumoto, Hiroto, Iizuka, Yoichi, Takasawa, Eiji, Akeda, Koji, Takegami, Norihiko, Funao, Haruki, Oshima, Yasushi, Kaito, Takashi, Sakai, Daisuke, Yoshii, Toshitaka, Ohba, Tetsuro, Otsuki, Bungo, Seki, Shoji, Miyazaki, Masashi, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2024
Full Text
View/download PDF

9. Neurological recovery rate and predictive factors of incomplete AIS grade C spinal cord injury in the older aged population

Author

Tamai, Koji, Terai, Hidetomi, Nakamura, Hiroaki, Yokogawa, Noriaki, Sasagawa, Takeshi, Nakashima, Hiroaki, Segi, Naoki, Ito, Sadayuki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Watanabe, Kota, Yamane, Junichi, Takeda, Kazuki, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Kuroda, Akiyoshi, Inoue, Gen, Kakutani, Kenichiro, Kakiuchi, Yuji, Kiyasu, Katsuhito, Tominaga, Hiroyuki, Tokumoto, Hiroto, Iizuka, Yoichi, Takasawa, Eiji, Akeda, Koji, Takegami, Norihiko, Funao, Haruki, Oshima, Yasushi, Kaito, Takashi, Sakai, Daisuke, Yoshii, Toshitaka, Ohba, Tetsuro, Otsuki, Bungo, Seki, Shoji, Miyazaki, Masashi, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2024
Full Text
View/download PDF

10. On Lehmer's problem and related problems

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11A25, Secondary 11A05, 11N25
Abstract

We show that if $N\pm 1=M\varphi(N)$ with $N\neq 15, 255$ composite, then $M<15.76515\log\log\log N$ and $M<16.03235\log\log\omega(N)$, together with similar results for the unitary totient function, Dedekind function, and the sum of unitary divisors., Comment: 14 pages (Added arguments in cases $N$, $N_1$, or $\omega(N)$ is small. Our results make no sense when $N_1\leq 17$ or $\omega(N)\leq 2$. Moreover, our argument does not work when $N_1=21$ in Theorems 1 or $\omega(N)=3$ in Theorems 2 and 4. Indeed, $N=15, 255$ satisfy $N+1=2\varphi(N)$ but $\log\log\log 15$ and $\log\log\omega(15)$ are negative and $2>21\log\log\omega(255)$)

Published
2023

11. A laser interferometer accelerometer for vibration sensitive cryogenic experiments

Author

Bajpai, Rishabh, Tomaru, Takayuki, Yamamoto, Kazuhiro, Ushiba, Takafumi, Kimura, Nobuhiro, Suzuki, Toshikazu, Yamada, Tomohiro, and Honda, Tohru

Subjects
Physics - Instrumentation and Detectors
Abstract

Monitoring motion originating from ultra low-temperature cooling systems like cryocoolers is important for vibration sensitive cryogenic experiments like KAGRA. Since no commercial cryogenic accelerometers are available, we developed a compact self-calibrating accelerometer with a Michelson interferometer readout for cryogenic use. Change in calibration factor and drop in interferometer output originating from temperature drop were the main concerns which were tackled. Sensitivity of $3.38\times10^{-11}$ m/$\sqrt{\mathrm{Hz}}$ at 1 Hz was achieved at 300 K. The accelerometer was tested inside the KAGRA cryostat; showed stable operation down to 12 K in 0.1-100 Hz band with only 1% visibility drop. Our accelerometer can be employed in low vibration cryogenic environment for a multitude of applications.

Published
2022
Full Text
View/download PDF

16. Prognostic impact of respiratory dysfunction in elderly patients with cervical spinal cord injury and/or fractures: a multicenter survey

Author

Hirota, Ryosuke, Terashima, Yoshinori, Ohnishi, Hirofumi, Yamashita, Toshihiko, Yokogawa, Noriaki, Sasagawa, Takeshi, Nakashima, Hiroaki, Segi, Naoki, Ito, Sadayuki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Watanabe, Kota, Nori, Satoshi, Takeda, Kazuki, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Terai, Hidetomi, Tamai, Koji, Kuroda, Akiyoshi, Inoue, Gen, Kakutani, Kenichiro, Kakiuchi, Yuji, Kiyasu, Katsuhito, Tominaga, Hiroyuki, Tokumoto, Hiroto, Iizuka, Yoichi, Takasawa, Eiji, Akeda, Koji, Takegami, Norihiko, Funao, Haruki, Oshima, Yasushi, Kaito, Takashi, Sakai, Daisuke, Yoshii, Toshitaka, Ohba, Tetsuro, Otsuki, Bungo, Seki, Shoji, Miyazaki, Masashi, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2023
Full Text
View/download PDF

21. Characteristics of the cervical spine and cervical cord injuries in older adults with cervical ossification of the posterior longitudinal ligament

Author

Okuwaki, Shun, Funayama, Toru, Koda, Masao, Eto, Fumihiko, Yamaji, Akihiro, Yokogawa, Noriaki, Sasagawa, Takeshi, Ando, Kei, Nakashima, Hiroaki, Segi, Naoki, Watanabe, Kota, Nori, Satoshi, Takeda, Kazuki, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Terai, Hidetomi, Tamai, Koji, Shirasawa, Eiki, Inoue, Gen, Kakutani, Kenichiro, Kakiuchi, Yuji, Kiyasu, Katsuhito, Tominaga, Hiroyuki, Tokumoto, Hiroto, Iizuka, Yoichi, Takasawa, Eiji, Akeda, Koji, Takegami, Norihiko, Funao, Haruki, Oshima, Yasushi, Kaito, Takashi, Sakai, Daisuke, Yoshii, Toshitaka, Ohba, Tetsuro, Otsuki, Bungo, Seki, Shoji, Miyazaki, Masashi, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2023
Full Text
View/download PDF

25. Influence of the timing of surgery for cervical spinal cord injury without bone injury in the elderly: A retrospective multicenter study

Author

Nori, Satoshi, Watanabe, Kota, Takeda, Kazuki, Yamane, Junichi, Kono, Hitoshi, Yokogawa, Noriaki, Sasagawa, Takeshi, Ando, Kei, Nakashima, Hiroaki, Segi, Naoki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Terai, Hidetomi, Tamai, Koji, Shirasawa, Eiki, Inoue, Gen, Kiyasu, Katsuhito, Iizuka, Yoichi, Takasawa, Eiji, Funao, Haruki, Kaito, Takashi, Yoshii, Toshitaka, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2024
Full Text
View/download PDF

26. Explicit sieve estimates and nonexistence of odd multiperfect numbers of a certain form

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11A25, secondary 11A05, 11N25, 11N36
Abstract

We prove explicit asymptotic formulae for some functions used in sieve methods and show that there exists no odd multiperfect number of abundancy four whose squared part is cubefree., Comment: 17 pages (The proof of Lemma 2.3 is refined and Theorem 3.1 is improved, freeing us from checking exceptional primes), the author's final version. Appeared in International J. Number Theory (Online Ready)

Published
2021
Full Text
View/download PDF

30. Cryogenic suspension design for a kilometer-scale gravitational-wave detector

Author

Ushiba, Takafumi, Akutsu, Tomotada, Aso, Yoichi, Araki, Sakae, Bajpai, Rishabh, Chen, Dan, Craig, Kieran, Creus, William, Enomoto, Yutaro, Fujii, Yoshinori, Fukunaga, Masashi, Hagiwara, Ayako, Haino, Sadakazu, Hasegawa, Kunihiko, Inoue, Yuki, Izumi, Kiwamu, Kimura, Nobuhiro, Kokeyama, Keiko, Kumar, Rahul, Majorana, Ettore, Michimura, Yuta, Miyamoto, Takahiro, Miyoki, Shinji, Murakami, Iwao, Namai, Yoshikazu, Nakano, Masayuki, Ochi, Toshiro, Ohashi, Masatake, Okutomi, Koki, Saito, Yoshio, Shishido, Takaharu, Shoda, Ayaka, Somiya, Kentaro, Suzuki, Toshikazu, Takada, Suguru, Takahashi, Masahiro, Takahashi, Ryutaro, Tanaka, Hiroki, Terashima, Shinichi, Tomaru, Takayuki, Travasso, Flavio, Ueda, Ayako, Vocca, Helios, Yamada, Tomohiro, Yamamoto, Kazuhiro, and Zeidler, Simon

Subjects
Physics - Instrumentation and Detectors
Abstract

We report the mirror suspension design for Large-scale Cryogenic Gravitational wave Telescope, KAGRA, during bKAGRA Phase 1. Mirror thermal noise is one of the fundamental noises for room-temperature gravitational-wave detectors such as Advanced LIGO and Advanced Virgo. Thus, reduction of thermal noise is required for further improvement of their sensitivity. One effective approach for reducing thermal noise is to cool the mirrors. There are many technical challenges that must be overcome to cool the mirrors, such as cryocooler induced vibrations, thermal drift in suspensions, and reduction in duty cycling due to the increased number of potential failure mechanisms. Our mirror suspension has a black coating that makes radiative cooling more efficient. For conduction cooling, we developed ultra high purity aluminum heat links, which yield high thermal conductivity while keeping the spring constant sufficiently small. A unique inclination adjustment system, called moving mass, is used for aligning the mirror orientation in pitch. Photo-reflective displacement sensors, which have a large range, are installed for damping control on marionette recoil mass and intermediate recoil mass. Samarium cobalt magnets are used for coil-magnet actuators to prevent significant change of magnetism between room temperature and cryogenic temperature. In this paper, the design of our first cryogenic payload and its performance during bKAGRA Phase 1 are discussed., Comment: 18 pages, 9 figures

Published
2020
Full Text
View/download PDF

31. Prospects for improving the sensitivity of the cryogenic gravitational wave detector KAGRA

Author

Michimura, Yuta, Komori, Kentaro, Enomoto, Yutaro, Nagano, Koji, Nishizawa, Atsushi, Hirose, Eiichi, Leonardi, Matteo, Capocasa, Eleonora, Aritomi, Naoki, Zhao, Yuhang, Flaminio, Raffaele, Ushiba, Takafumi, Yamada, Tomohiro, Wei, Li-Wei, Takeda, Hiroki, Tanioka, Satoshi, Ando, Masaki, Yamamoto, Kazuhiro, Hayama, Kazuhiro, Haino, Sadakazu, and Somiya, Kentaro

Subjects
General Relativity and Quantum Cosmology, Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

Upgrades to improve the sensitivity of gravitational wave detectors enable more frequent detections and more precise source parameter estimation. Unlike other advanced interferometric detectors such as Advanced LIGO and Advanced Virgo, KAGRA requires different approach for the upgrade since it is the only detector which employs cryogenic cooling of the test masses. In this paper, we describe possible KAGRA upgrades with technologies focusing on different detector bands, and compare the impacts on the detection of compact binary coalescences. We show that either fivefold improvement in the $100 M_{\odot}$--$100 M_{\odot}$ binary black hole range, a factor of 1.3 improvement in the binary neutron star range, or a factor of 1.7 improvement in the sky localization of binary neutron stars is well feasible with upgrades that do not require changes in the existing cryogenic or vacuum infrastructure. We also show that twofold broadband sensitivity improvement is possible by applying multiple upgrades to the detector., Comment: 10 pages, 2 figures

Published
2020
Full Text
View/download PDF

32. High Performance Heat Conductor with Small Spring Constant for Cryogenic Applications

Author

Yamada, Tomohiro, Tomaru, Takayuki, Suzuki, Toshikazu, Ushiba, Takafumi, Kimura, Nobuhiro, Takada, Suguru, Inoue, Yuki, and Kajita, Takaaki

Subjects
Physics - Instrumentation and Detectors
Abstract

We developed a soft and high thermal conductive heat link for cryogenic applications. The measured maximum thermal conductivity was approximately 18500 W/m/K at 10 K. This spring constant was 1/43 of that of a single thick wire with the same cross-sectional area at room temperature. We realized these performances by utilizing high purity aluminum (99.9999 %, 6N) and by stranding many thin wires that are 0.15 mm in diameter. The electrical Residual Resistivity Ratio (RRR) was also measured and used to estimate the thermal conductivity by Wiedemann-Franz law. We observed the size effect on the electrical conductivity, and evaluated the effect of mechanical deformation to the RRR. These evaluations allow us to design a pragmatic heat link for cryogenic application., Comment: 13 pages, 6 figures

Published
2020
Full Text
View/download PDF

33. Necessary conditions for binomial collisions

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11B65, Secondary 11A05, 11D61, 11D72
Abstract

We shall give some necessary conditions for the equation $\binom{x}{a}=\binom{y}{b}$ to hold: if $\binom{2n+\delta}{n-m}=\binom{2n+l}{n-k}$ with $\delta=0$ or $1$, $0(cn/\log n)^{40/21}$ for some constant $c$., Comment: 14 pages

Published
2020

36. On Sinha's note on perfect numbers

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, 11A05, 11A25
Abstract

We shall show that there is no odd perfect number of the form $2^n+1$ or $n^n+1$., Comment: 7 pages, title changed, too long for a note, some revisions to contents

Published
2019

37. On a problem of De Koninck

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Mathematics - Combinatorics, 05C20, 11A05, 11A25, 11A41
Abstract

Let $\sigma(n)$ and $\gamma(n)$ denote the sum of divisors and the product of distinct prime divisors of $n$ respectively. We shall show that, if $n\neq 1, 1782$ and $\sigma(n)=(\gamma(n))^2$, then there exist odd (not necessarily distinct) primes $p, p^\prime$ and (not necessarily odd) distinct primes $q_i (i=1, 2, \ldots, k)$ such that $p, p^\prime\mid\mid n$, $q_i^2\mid\mid n (i=1, 2, \ldots, k)$ and $q_1\mid \sigma(p^2), q_{i+1}\mid\sigma(q_i^2) (1\leq i\leq k-1), p^\prime \mid\sigma(q_k^2)$., Comment: 15 pages, the author's final version, address changed due to the location change of the Minoh Campus of Osaka University, to appear in Moscow J. Combin. Number Theory

Published
2019
Full Text
View/download PDF

40. Does surgery improve neurological outcomes in older individuals with cervical spinal cord injury without bone injury? A multicenter study

Author

Nori, Satoshi, Watanabe, Kota, Takeda, Kazuki, Yamane, Junichi, Kono, Hitoshi, Yokogawa, Noriaki, Sasagawa, Takeshi, Ando, Kei, Nakashima, Hiroaki, Segi, Naoki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Terai, Hidetomi, Tamai, Koji, Shirasawa, Eiki, Inoue, Gen, Kiyasu, Katsuhito, Iizuka, Yoichi, Takasawa, Eiji, Funao, Haruki, Kaito, Takashi, Yoshii, Toshitaka, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2022
Full Text
View/download PDF

42. Three-term Machin-type formulae

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, 11D61, 11Y60, 33B10
Abstract

We shall show that there exist only finitely many nondegenerate three-term Machin-type formulae and give explicit upper bounds for the sizes of variables., Comment: 22 pages, some errors corrected, calcuation based on another preprint arXiv:1906.00419, see https://tyamada1093.web.fc2.com/math/files/deq0014revision.txt

Published
2018

43. An analog of perfect numbers involving the unitary totient function

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11A05, 11N36, Secondary 11A25, 11A51
Abstract

We shall give some results for an integer divisible by its unitary totient., Comment: 22 pages, the author's final version, published in J. Number Theory (online), some results have been omitted since more stronger results have been shown

Published
2018
Full Text
View/download PDF

44. An exponential diophantine equation related to odd perfect numbers

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11D45, 11D61, Secondary 11A05, 11A25, 11A51, 11J68
Abstract

We shall show that, for any given primes $\ell\geq 17$ and $p, q\equiv 1\pmod{\ell}$, the diophantine equation $(x^\ell-1)/(x-1)=p^m q$ has at most four positive integral solutions $(x, m)$ and give its application to odd perfect number problem., Comment: 11 pages, filled some gaps and constants changed due to correction of our old paper in Colloq. Math. 156 (2019), 15--23. (see ibid. 162 (2019), 311--313)

Published
2018

45. A generalization of the Ramanujan-Nagell equation

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, 11D61 (Primary), 11D45 (Secondary)
Abstract

We shall show that, for any positive integer $D>0$ and any primes $p_1, p_2$ not dividing $D$, the diophantine equation $x^2+D=2^s p_1^k p_2^l$ has at most $63$ integer solutions $(x, k, l, s)$ with $x, k, l\geq 0$ and $s\in \{0, 2\}$., Comment: 12 pages

Published
2017

47. Differences in clinical characteristics of cervical spine injuries in older adults by external causes: a multicenter study of 1512 cases

Author

Yokogawa, Noriaki, Kato, Satoshi, Sasagawa, Takeshi, Hayashi, Hiroyuki, Tsuchiya, Hiroyuki, Ando, Kei, Nakashima, Hiroaki, Segi, Naoki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Nori, Satoshi, Yamane, Junichi, Furuya, Takeo, Yunde, Atsushi, Nakajima, Hideaki, Yamada, Tomohiro, Hasegawa, Tomohiko, Terashima, Yoshinori, Hirota, Ryosuke, Suzuki, Hidenori, Imajo, Yasuaki, Ikegami, Shota, Uehara, Masashi, Tonomura, Hitoshi, Sakata, Munehiro, Hashimoto, Ko, Onoda, Yoshito, Kawaguchi, Kenichi, Haruta, Yohei, Suzuki, Nobuyuki, Kato, Kenji, Uei, Hiroshi, Sawada, Hirokatsu, Nakanishi, Kazuo, Misaki, Kosuke, Terai, Hidetomi, Tamai, Koji, Shirasawa, Eiki, Inoue, Gen, Kakutani, Kenichiro, Kakiuchi, Yuji, Kiyasu, Katsuhito, Tominaga, Hiroyuki, Tokumoto, Hiroto, Iizuka, Yoichi, Takasawa, Eiji, Akeda, Koji, Takegami, Norihiko, Funao, Haruki, Oshima, Yasushi, Kaito, Takashi, Sakai, Daisuke, Yoshii, Toshitaka, Ohba, Tetsuro, Otsuki, Bungo, Seki, Shoji, Miyazaki, Masashi, Ishihara, Masayuki, Okada, Seiji, Imagama, Shiro, and Watanabe, Kota

Published
2022
Full Text
View/download PDF

48. A multicenter study of 1-year mortality and walking capacity after spinal fusion surgery for cervical fracture in elderly patients

Author

Sasagawa, Takeshi, Yokogawa, Noriaki, Hayashi, Hiroyuki, Tsuchiya, Hiroyuki, Ando, Kei, Nakashima, Hiroaki, Segi, Naoki, Watanabe, Kota, Nori, Satoshi, Takeda, Kazuki, Furuya, Takeo, Yunde, Atsushi, Ikegami, Shota, Uehara, Masashi, Suzuki, Hidenori, Imajo, Yasuaki, Funayama, Toru, Eto, Fumihiko, Yamaji, Akihiro, Hashimoto, Ko, Onoda, Yoshito, Kakutani, Kenichiro, Kakiuchi, Yuji, Suzuki, Nobuyuki, Kato, Kenji, Terashima, Yoshinori, Hirota, Ryosuke, Yamada, Tomohiro, Hasegawa, Tomohiko, Kawaguchi, Kenichi, Haruta, Yohei, Seki, Shoji, Tonomura, Hitoshi, Sakata, Munehiro, Uei, Hiroshi, Sawada, Hirokatsu, Tominaga, Hiroyuki, Tokumoto, Hiroto, Kaito, Takashi, Iizuka, Yoichi, Takasawa, Eiji, Oshima, Yasushi, Terai, Hidetomi, Tamai, Koji, Otsuki, Bungo, Miyazaki, Masashi, Nakajima, Hideaki, Nakanishi, Kazuo, Misaki, Kosuke, Inoue, Gen, Kiyasu, Katsuhito, Akeda, Koji, Takegami, Norihiko, Yoshii, Toshitaka, Ishihara, Masayuki, Okada, Seiji, Aoki, Yasuchika, Harimaya, Katsumi, Murakami, Hideki, Ishii, Ken, Ohtori, Seiji, Imagama, Shiro, and Kato, Satoshi

Published
2022
Full Text
View/download PDF

49. Development of a DNA aptamer that binds to the complementarity-determining region of therapeutic monoclonal antibody and affinity improvement induced by pH-change for sensitive detection

Author

Saito, Taro, Shimizu, Yutaka, Tsukakoshi, Kaori, Abe, Koichi, Lee, Jinhee, Ueno, Kinuko, Asano, Ryutaro, Jones, Brian V., Yamada, Tomohiro, Nakano, Tatsuki, Tong, Jiaxing, Hishiki, Asami, Hara, Kodai, Hashimoto, Hiroshi, Sode, Koji, Toyo’oka, Toshimasa, Todoroki, Kenichiro, and Ikebukuro, Kazunori

Published
2022
Full Text
View/download PDF

50. A new upper bound for odd perfect numbers of a special form

Author

Yamada, Tomohiro

Subjects
Mathematics - Number Theory, Primary 11A05, 11A25, Secondary 11D61, 11J86
Abstract

We shall given a new effectively computable upper bound of odd perfect numbers whose Euler factors are powers of fixed exponent, improving our old result in T. Yamada, Colloq. Math. 103 (2005), 303--307., Comment: 10 pages, the author's revised version; 3 pages, corrigendum to the previous (published in the journal) version

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results