Pairing Cryptography Meets Isogeny: A New Framework of Isogenous Pairing Groups

We put forth a new mathematical framework called Isogenous Pairing Groups (IPG) and new intractable assumptions in the framework, the Isogenous DBDH (Isog-DBDH) assumption and its variants. Three operations, i.e., exponentiation, pairing and isogeny on elliptic curves are treated under a unified notion of trapdoor homomorphisms, and combinations of the operations have potential new cryptographic applications, in which the compatibility of pairing and isogeny is a main ingredient in IPG. As an example, we present constructions of (small and large universe) key-policy attribute-based encryption (KP-ABE) schemes secure against pre-challenge quantum adversaries in the quantum random oracle model (QROM). Note that our small universe KP-ABE has asymptotically the same efficiency as Goyal et al.\u27s small universe KP-ABE, which has only classical security. As a by-product, we also propose practical (hierarchical) identity-based encryption ((H)IBE) schemes secure against pre-challenge quantum adversaries in the QROM from isogenies, which are based on the Boneh-Franklin IBE and the Gentry-Silverberg HIBE, respectively

Phase shift spectra of a fiber-microsphere system at the single photon level

We succeeded in measuring phase shift spectra of a microsphere cavity coupled with a tapered fiber using a weak coherent probe light at the single photon level. We utilized a tapered fiber with almost no depolarization and constructed a very stable phase shift measurement scheme based on polarization analysis using photon counting. Using a very weak probe light (\bar{n} = 0:41), we succeeded in observing the transition in the phase shift spectrum between undercoupling and overcoupling (at gap distances of 500 and 100 nm, respectively).We also used quantum state tomography to obtain a 'purity spectrum'. Even in the overcoupling regime, the average purity was 0.982 \pm 0.024 (minimum purity: 0.892), suggesting that the coherence of the fiber-microsphere system was well preserved. Based on these results, we believe this system is applicable to quantum phase gates using single light emitters such as diamond nitrogen vacancy centers.Comment: 8 pages, 3 figure

接地電極のサージインピーダンスに関する研究

金沢大工学部1.接地インピーダンスの数値計算…‥地中電流の作る磁界の影響を考慮に入れた改良計算法を用いて、雷サージに対する接地インピーダンスの数値計算を行った。得られた知見を要約すると、(1)地中電流の作る磁界は、地表面と平行に埋設された電極(メッシュ電極、カウンターポイズ)には影響しない。(2)地表面と垂直に埋設された電極(垂直棒状電極,深埋電極)に対しては、地中電流の作る磁界は電極のインダクタンスをかなり増大させる。2.接地インピーダンスの実測…‥サージインピーダンステスタ(立上り1μ秒,0.4A)を用いて、実際の垂直棒状電極の接地インピーダンスを測定した。その結果、電極をある程度以上長くしても接地インピーダンスが減少しないこと、すなわみ、接地インピーダンスに関しては電極の有効長が存在することが判明した。この電極の有効長は電極のインダクタンス電圧降下に起因するものである。そして、(1)有効長は垂直埋設電極に対してはもちろんのこと、水平埋設電極に対しても存在すること、(2)理論的考察から、大地固有抵抗が変われば有効長も変わること、(3)例えば、大地固有抵抗が158〜190(Ωm)のときの垂直棒状電極の有効長は約20mであること、が判明した。3.今後の課題‥…計算値と実測値を比較したところ、電極が短い(2m程度)場合には計算誤差は小さいが、電極が長い(10m程度以上)場合の誤差はかなり大きくなった。この原因を検討したところ、前述の計算において伝播が無視されていたためであろうと推定された。したがって、伝播を考慮に入れた接地インピーダンス計算法を案出することが必要である。Surge impedances of grounding electrodes were studied in numerical calculations and in field measurements.(1) In the numerical calculations, the magnetic field induced by the ground current (current which was injected from the grounding electrode into the ground) was taken into account. It was found that this magnetic field considerably increased the inductance of the vertical electrode, but did not influence the inductance of the horizontal electrode.(2) In the field measurements, surge impedances of actual vertical linear electrodes were measured by the use of a surge-impedance tester (current of 0.4 A, building-up time of 1 sec). It was found that the grounding impedance of the vertical electrode did not much decrease even if the electrde was much lengthened, while the grounding resistance much decreased then. Namely there was an effective length of the electrode from the viewpoint of grounding impedance. For an example, the effective length of the vertical electrode was about 20 m, when the resistivity of the soil was 158-190 m. As to the effective length, there is an effective length also for a horizontal electrode, and the effective length for each electrode\u27s type is defferent when the resistivity of the soil is different.(3) In comparison between the calculated impedances and the measured ones, when the electrode was short (about 2 m), the calculated impedance nearly agreed with the measured one, but, when the electrode was long (10-200 m), the calculated one was much greater than the measured one. The reason for the error was sought and seemed that the effect of the attenuation in the propagation was not taken into account in the calculation. Thus a problem in the future is that an improved method of calculation needs to be proposed, where the attenuation is taken into account.研究課題/領域番号:60550199, 研究期間(年度):1985 – 1986出典：研究課題「接地電極のサージインピーダンスに関する研究」課題番号60550199（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-60550199/605501991986kenkyu_seika_hokoku_gaiyo/）を加工して作

架空線上の進行波現象におよぼす積雪の影響

金沢大学工学部研究課題/領域番号:X42440-----53175, 研究期間(年度):1967出典：研究課題「架空線上の進行波現象におよぼす積雪の影響」課題番号X42440-----53175（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-X42440-----53175/）を加工して作

MeV protons in the inner belt and slot region observed by HEP onboard the Arase satellite

The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. /Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Evaluation of single silicon vacancy centers in nanodiamonds created by ion implantation at cryogenic temperatures

Silicon vacancy (SiV) centers in diamonds have attracted much attention because of their stability and narrow emission linewidth, and are promising for applications in quantum information technology. SiV-center-encapsulated nanodiamonds have also attracted much attention because of their potential to be coupled to various photonic devices. One efficient way to fabricate nanodiamonds that contain SiV centers is Si ion implantation into nanodiamonds. However, the evaluation of a single SiV center in a nanodiamond produced by this method at low temperatures has not been performed. In this study, we report on the optical properties of a single SiV center in a nanodiamond produced by ion implantation at cryogenic temperatures. The emission spectrum from a single SiV center (g²(0) = 0.19) was observed with four distinct fine splittings of the zero-phonon line (ZPL) at 4 K. At an excitation power of 50µW, the full width at half maximum of the ZPL reached the spectrometer resolution limit (0.09 nm). The temperature dependence of the emission peak is consistent with that of the emission coming from an SiV center under high strain. The results obtained in this work suggest that nanodiamonds containing single SiV centers formed using this method will be an important building block for the realization of quantum information applications

Postoperative Urinary Retention in Japanese Elderly Males with a Femoral Neck or Trochanteric Fracture

We assessed risk factors for postoperative urinary retention (UR) in elderly males with femoral bone fractures: 169 Japanese males (mean age 81.95 ± 1.19 years) who had undergone hip surgery at a municipal hospital (Toyama, Japan). A multiple logistic regression analysis was used to test possible risk factors for UR: age, body mass index, serum albumin, cognitive impairment, activities of daily living (ADL), and history of diabetes mellitus (DM). UR occurred in 24 (14.2%) of the 169 patients. A multivariate logistic regression analysis with age adjustment showed that ADL (odds ratio [OR] 3.88; 95% confidence interval [CI]: 1.2-12.5, p=0.023) was significantly associated with the development of UR, and a history of DM showed marginal significance for UR occurrence (OR 0.36, 95%CI: 0.11-10, p=0.064). These results suggests that ADL is a risk factor for UR development in elderly males who have undergone surgery for femoral neck or trochanter fractures

Adipose-derived regenerative cells exert beneficial effects on systemic responses following myocardial ischemia/reperfusion

Background: Acute coronary syndrome leads to systemic responses, including activation of the sympathetic nervous system, inflammation of atherosclerotic lesions, changes in metabolism and gene expressions of remote organs such as the spleen, bone marrow, and liver. Clinical trials and experimental studies have demonstrated that therapy with adipose-derived regenerative cells (ADRCs) attenuates myocardial ischemia/reperfusion (I/R) injury. The aim of this study is to investigate the role of ADRCs in regulating systemic reactions following I/R.Methods: Isolated ADRCs were obtained from green fluorescent protein transgenic male mice. Flow cytometry revealed that freshly isolated ADRCs expressed stem cell markers CD90 and Sca-1, and mesenchymal lineage marker. These cells exhibited multilineage differentiation into adipogenic, osteogenic, and chondrogenic lineages. Wild-type mice were subjected to 30 min of left ascending coronary ischemia and 24 h reperfusion. Freshly isolated ADRCs (105 cells) or vehicle (VEH), were administered intravenously through the tail at the time of reperfusion.Results: Compared to VEH, administration of ADRCs significantly reduced circulating troponin levels 24 h after I/R. Using quantitative real-time polymerase chain reaction analysis, the present study confirms that I/R-induced increase of factor X mRNA expression in the liver and was significantly inhibited by ADRCs compared to VEH. Administration of ADRCs significantly reduced the I/R-induced increase in serum levels of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-18 seen in mice receiving VEH.Conclusions: These results suggest that administration of ADRCs could have an important role in reducing myocardial injury and regulating the hepatic gene expression profile following I/R

Creation of silicon vacancy color centers with a narrow emission line in nanodiamonds by ion implantation

Nanodiamonds containing silicon-vacancy (SiV) centers with high brightness, high photo-stability, and a narrow zero phonon line (ZPL) have attracted attention for bioimaging, nanoscale thermometry, and quantum technologies. One method to create such nanodiamonds is the milling of diamond films synthesized by chemical vapor deposition (CVD). However, this requires post-processing such as acid treatment and centrifugation after the milling process. Therefore, the number of SiV center-containing nanodiamonds made from an initial CVD diamond is small. An alternative method without these problems is the implantation of Si ions into preselected nanodiamonds. This method, however, has an issue regarding the ZPL linewidths, which are more than twice as broad as those in nanodiamonds synthesized by CVD. In order to reduce the linewidth, we employed annealing treatment at high temperatures (up to 1100°C) and high vacuum after the implantation. For an ion fluence of 1013 ions/cm2, a ZPL with a linewidth of about 7 nm at room temperature was observed for a nanodiamond with a median size of 29.9 ± 16.0 nm. This was close to the linewidth for nanodiamonds created by CVD

Comparative study of the inial spikes of SGR giant flares in 1998 and 2004 observed with GEOTAIL: Do magnetospheric instabilities trigger large scale fracturing of magnetar's crust?

We present the unsaturated peak profile of SGR 1900+14 giant flare on 1998 August 27. This was obtained by particle counters of the Low Energy Particle instrument onboard the GEOTAIL spacecraft. The observed peak profile revealed four characteristic structures: initial steep rise, intermediate rise to the peak, exponential decay and small hump in the decay phase. From this light curve, we found that the isotropic peak luminosity was $2.3\times10^{46}$ erg s$^{-1}$ and the total energy was $4.3 \times 10^{44}$ erg s$^{-1}$ ($E\gtrsim$ 50 keV), assuming that the distance to SGR 1900+14 is 15 kpc and that the spectrum is optically thin thermal bremsstrahlung with $kT =$ 240 keV. These are consistent with the previously reported lower limits derived from Ulysses and Konus-Wind observations. A comparative study of the initial spikes of SGR 1900+14 giant flare in 1998 and SGR 1806-20 in 2004 is also presented. The timescale of the initial steep rise shows the magnetospheric origin, while the timescale of the intermediate rise to the peak indicates that it originates from the crustal fracturing. Finally, we argue that the four structures and their corresponding timescales provide a clue to identify extragalactic SGR giant flares among short GRBs.Comment: 12 pages, 3 figures, accepted by ApJ