Enhancement of second harmonic generation in a doubly resonant metamaterial

We investigate second harmonic (SH) generation in a doubly resonant metamaterial. We show that SH generation can be enhanced when the resonant condition is satisfied for the SH frequency as well as for the fundamental frequency. A unit cell of the doubly resonant metamaterial consists of two coupled resonators, one of which resonates at the fundamental frequency, whereas the other resonates around the SH frequency. We observe that the SH generation in the doubly resonant metamaterial is 4.6 times as large as that in a singly resonant metamaterial.Comment: 4 pages, 4 figure

Search for Lepton Flavor Violation in the Higgs Boson Decay at a Linear Collider

We discuss possibility of direct search for lepton flavor violation (LFV) in Yukawa interaction by measuring the branching ratio for the decay of the lightest Higgs boson ($h^0$) into a $\tau$-$\mu$ pair at a linear collider. We study the significance of the signal process, $e^+e^- \to Z^\ast \to Z h^0 \to Z \tau^\pm \mu^\mp$, against the backgrounds such as $e^{+}e^{-} \to Z \tau^{+}\tau^{-} \to Z \tau^{\pm}\mu^{\mp}+$ missings. After taking appropriate kinematic cuts, the number of the background event is considerably reduced, so that the signal can be visible when the branching ratio of $h^0 \to \tau^\pm \mu^\mp$ is larger than about $10^{-4}$. In a Minimal Supersymmetric Standard Model scenario, the effective coupling of $h^0 \tau^\pm \mu^\mp$ can be generated at loop level due to the slepton mixing. When supersymmetric mass parameters are larger than TeV scales, the branching ratio can be as large as several times $10^{-4}$. Therefore, the signal can be marginally visible at a LC. In the general two Higgs doublet model, the possible maximal value for the branching ratio of $h^0 \to \tau^\pm \mu^\mp$ can reach to a few times $10^{-3}$ within the available experimental bound, so that we can obtain larger significance.Comment: 14 pages 3 figures, REVTEX4, version accepted for publication in Physics Letters

Remarks on flavor-neutrino propagators and oscillation formulae

We examine the general structure of the formulae of neutrino oscillations proposed by Blasone and Vitiello(BV). Reconstructing their formulae with the retarded propagators of the flavor neutrino fields for the case of many flavors, we can get easily the formulae which satisfy the suitable boundary conditions and are independent of arbitrary mass parameters $\{\mu_{\rho}\}$, as is obtained by BV for the case of two flavors. In this two flavor case, our formulae reduce to those obtained by BV under $T$-invariance condition. Furthermore, the reconstructed probabilities are shown to coincide with those derived with recourse to the mass Hilbert space ${\cal H}_{m}$ which is unitarily inequivalent to the flavor Hilbert space ${\cal H}_{f}$. Such a situation is not found in the corresponding construction a la BV. Then the new factors in the BV's formulae, which modify the usual oscill ation formulae, are not the trace of the flavor Hilbert space construction, but come from Bogolyubov transformation among the operators of spin-1/2 ne utrino with different masses.Comment: revtex, 16 page

Clinical preferences for DME in Japan

Aims/Introduction: To determine the current clinical preferences of anti‐vascular endothelial growth factor (VEGF) treatment protocols for diabetic macular edema (DME) in Japan. Materials and Methods: This was a descriptive cross‐sectional study. Answers to a questionnaire consisting of 16 questions were obtained from 176 of 278 (63.3%) surveyed ophthalmologists. Results: The results showed that 81.2% preferred intravitreal injections of anti‐VEGF antibodies as the first‐line therapy. The most important indicators for beginning anti‐VEGF therapy were: the best‐corrected visual acuity in 44.3% and the retinal thickness in 30.7%. In the loading phase, 53.4% preferred a single injection, and in the maintenance phase, 75.0% preferred the pro re nata regimen. Financial limitation (85.8%) was reported as the most important difficulty in the treatment. For combination therapy with anti‐VEGF treatment, panretinal photocoagulation, focal photocoagulations and a sub‐Tenon steroid injection were preferred. The contraindications for anti‐VEGF therapy were: prior cerebral infarction (72.7%). Regarding the use of both approved anti‐VEGF agents in Japan, ranibizumab and aflibercept, 39.8% doctors used them appropriately. Conclusions: Our results present the current clinical preferences of anti‐VEGF treatment for DME in Japan. The best‐corrected visual acuity and the retinal thickness are important indicators to institute this therapy. The majority of the ophthalmologists use anti‐VEGF treatment as first‐line therapy and prefer the 1 + pro re nata regimen

Relationship between RBC Mercury Levels and Serum n3 Polyunsaturated Fatty Acid Concentrations among Japanese Men and Women

Aims. To evaluate potential health risk and benefits of fish consumption, the association of fish consumption with total mercury levels in red blood cells (RBCs) and serum eicosapentaenoic acid (EPA) concentrations was examined. Subjects and Methods. Study subjects were 269 Japanese (98 men and 171 women) living in a remote island of Kagoshima, and their blood was drawn in 1994. Results. Total mercury levels were related to weekly fish consumption among women (P = 0.035) but not among men (P = 0.643). However, serum EPA levels were not related to fish consumption in both women and men. In contrast, EPA levels in the high-density ipoprotein (HDL) fraction of the sera were significantly related to fish consumption (P values for men and women were 0.014 and 0.073, resp.). Interestingly, mercury levels were related to serum EPA levels and EPA in the HDL fraction of the sera (P = 0.001) among women (P = 0.005) but not among men. Sex differences in fish species consumed may be an explanation for the observed sex difference. Conclusion. Those findings suggest that the health benefit of fish consumption can be maximized by the careful selection of fish species consumed

The electronic state of vortices in YBa2Cu3Oy investigated by complex surface impedance measurement

The electromagnetic response to microwaves in the mixed state of YBa2Cu3Oy(YBCO) was measured in order to investigate the electronic state inside and outside the vortex core. The magnetic-field dependence of the complex surface impedance at low temperatures was in good agreement with a general vortex dynamics description assuming that the field-independent viscous damping force and the linear restoring force were acting on the vortices. In other words, both real and imaginary parts of the complex resistivity, \rho_1, and \rho_2, were linear in B. This is explained by theories for d-wave superconductors. Using analysis based on the Coffey-Clem description of the complex penetration depth, we estimated that the vortex viscosity \eta at 10 K was (4 \sim 5) \times 10^{-7} Ns/m^2. This value corresponds to \omega_0 \tau \sim 0.3 - 0.5, where \omega_0 and \tau are the minimal gap frequency and the quasiparticle lifetime in the vortex core, respectively. These results suggest that the vortex core in YBCO is in the moderately clean regime. Investigation of the moderately clean vortex core in high-temperature superconductors is significant because physically new effects may be expected due to d-wave characteristics and to the quantum nature of cuprate superconductors. The behavior of Z_s as a function of B across the first order transition (FOT) of the vortex lattice was also investigated. Unlike Bi2Sr2CaCu2Oy (BSCCO), no distinct anomaly was observed around the FOT in YBCO. Our results suggest that the rapid increase of X_s due to the change of superfluid density at the FOT would be observed only in highly anisotropic two-dimensional vortex systems like BSCCO. We discuss these results in terms of the difference of the interlayer coupling and the energy scale between the two materials.Comment: 10 pages, 6 figures, to be published in Phys. Rev. B, one reference adde