One-dimensional broadband phononic crystal filter with unit cells made of two non-uniform impedance-mirrored elements

A one-dimensional finite-sized phononic crystal(PC) made of a specially-configured unit cell is proposed to realize broad bandpass, high-performance filtering. The unit cell is specially-configured with two elements having mirrored impedance distributions of each other. One element has a non-uniform impedance distribution that is so engineered as to maximize wave transmission in the pass band and to minimize transmission in the adjacent stop band while the other, exactly the mirrored distribution. The mirroring approach naturally yields the overall impedance contrast within the resulting unit cell, necessary to form stop bands in a PC of the unit cells. More importantly, the good transmission performance of the orginally-engineered element can be preserved by the approach because no additional impedance mismatch is introduced along the interface of the two impedance-mirrored elements. Extraordinary performance of the PC filter made of the proposed unit cell, such as high transmission, large bandwidth and sharp roll-off, is demonstrated by using one-dimensional longitudinal elastic wave problems. Copyright 2013 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [http://dx.doi.org/10.1063/1.4790638ope

The relationship of ovarian endometrioma and its size to the preoperative serum anti-Mullerian hormone level

Objectives: The aim of this study is to evaluate the impact of ovarian endometrioma according to its size on the serumanti-Mullerian hormone (AMH) levels compared to that of other benign ovarian cysts.Material and methods: The current study retrospectively evaluated preoperative serum AMH level and its association to presentingovarian cyst size which were measured in clinical setting. Women with surgically diagnosed endometrioma or other benignovarian cysts were included. All patients underwent transvaginal or transrectal ultrasonography to determine the size of theovarian cysts. Preoperative serum AMH level was checked and evaluated according to histologic type of the cyst, which wereendometrioma or other benign ovarian cysts, respectively. Both groups were classified into ≤ 4 cm, > 4 cm and ≤ 8 cm, > 8 cmand ≤ 12 cm, > 12 cm according to the diameter of cyst and analyzed the difference of mean AMH levels in both groups.Results: There was no significant difference in preoperative serum AMH level between the two groups (3.36 ± 2.3 versus3.76 ± 2.64, p = 0.331). The difference of preoperative AMH levels according to categorized cyst size also was not statisticallysignificant in both groups.Conclusions: Preoperative serum AMH levels were not statistically different between endometrioma and other benignovarian cyst groups and were not related to the size of endometrioma

Influence of the waist diameters on transmission characteristics and strain sensitivity of microtapered long-period fiber gratings

Transmission characteristics of microtapered long-period fiber gratings (MTLPGs) and their strain and temperature sensitivities with variations in the waist diameters are investigated theoretically and experimentally. Transmission characteristics of MTLPGs strongly depend on the waist diameter of the tapered optical fiber (TOF) because of the modification of the effective index difference between the core and the cladding modes. Based on the photoelastic effect, the resonant wavelengths of MTLPGs with variations in strain shift to shorter wavelengths. The strain sensitivity of the MTLPG with a waist diameter of 25 μm is improved by a factor of 20 compared with that of a 125 μm long-period fiber grating. The temperature sensitivities of MTLPGs are also enhanced by reducing the waist diameter of the TOF

Two distinct red giant branch populations in the globular cluster NGC 2419 as tracers of a merger event in the Milky Way

Recent spectroscopic observations of the outer halo globular cluster (GC) NGC 2419 show that it is unique among GCs, in terms of chemical abundance patterns, and some suggest that it was originated in the nucleus of a dwarf galaxy. Here we show, from the Subaru narrow-band photometry employing a calcium filter, that the red giant-branch (RGB) of this GC is split into two distinct subpopulations. Comparison with spectroscopy has confirmed that the redder RGB stars in the $hk$[=(Ca$-b)-(b-y)$] index are enhanced in [Ca/H] by $\sim$0.2 dex compared to the bluer RGB stars. Our population model further indicates that the calcium-rich second generation stars are also enhanced in helium abundance by a large amount ($\Delta$Y = 0.19). Our photometry, together with the results for other massive GCs (e.g., $\omega$ Cen, M22, and NGC 1851), suggests that the discrete distribution of RGB stars in the $hk$ index might be a universal characteristic of this growing group of peculiar GCs. The planned narrow-band calcium photometry for the Local Group dwarf galaxies would help to establish an empirical connection between these GCs and the primordial building blocks in the hierarchical merging paradigm of galaxy formation.Comment: 4 pages, 4 figures, 1 table, accepted for the publication in ApJ