A new design method of an ultra-wideband circularly-polarized planar multiple-input-multiple-output (MIMO) antenna is presented in this paper. The proposed MIMO antenna consists of four unit cell antennas, being comprised of a microstrip feed line and a square slotted ground plane. In the proposed unit cell design, a circular stub is protruded from the ground plane strip for achieving circular polarization. The unit cell of the MIMO antenna is optimized by adjusting design parameters. The compact four-port MIMO antenna prototype is designed on the FR4 substrate with the overall dimensions of 45 × 45 × 1.6 mm3. The proposed four-port MIMO antenna design provides an impedance bandwidth (S11 < −10 dB) of 112% (3.1–11 GHz) and a 3 dB axial ratio bandwidth of 36% (4.8–6.9 GHz). The performance of the fabricated MIMO antenna shows good agreement between the EM simulation and measurement results.

Among domesticated traits, pre-harvest sprouting (PHS) caused by the early breakage of dormancy leads to severe economic losses. Therefore, regulating PHS is important for cereal crop improvement against changes in climate. In this study, we surveyed naturally occurring variations in seed germination in diverse rice germplasm for the available resources of this trait, and investigated the changes of abscisic acid (ABA) levels during grain development by the distinguished PHS-resistant groups. We discovered wide variations in germination among the 205 rice accessions examined and found that 90 accessions are resistant (germination <20%) to PHS. Tropical and subtropical accessions, which are subjected to long wet periods, are more resistant to PHS than the other accessions. We detected an increase in germination of detached seeds from the panicle compared with intact seeds in panicle at harvesting time. This might be attributed to a weakening of the mechanical barrier that prevents water imbibition and radical emergence. ABA levels were maximal at 10 d after flowering and decreased thereafter. Interestingly, PHS-susceptible accessions maintained higher or similar ABA levels compared with PHS-resistant accessions, suggesting that the key factors for seed dormancy and its breakage are ABA perception and signal transduction rather than total ABA content. The diversity of germination ability detected in this study could be sustainably used for crop improvement and to help unveil the genetic and physiological basis of this quantitative trait.

A CoCrFeNiMn high-entropy alloy (HEA), in the form of a face-centered cubic (fcc) solid solution, was processed by high-pressure torsion (HPT) to produce a nanocrystalline (nc) HEA. Significant grain refinement was achieved from the very early stage of HPT through 1/4 turn and an nc structure with an average grain size of ∼40 nm was successfully attained after 2 turns. The feasibility of significant microstructural changes was attributed to the occurrence of accelerated atomic diffusivity under the torsional stress during HPT. Nanoindentation experiments showed that the hardness increased significantly in the nc HEA during HPT processing and this was associated with additional grain refinement. The estimated values of the strain-rate sensitivity were maintained reasonably constant from the as-cast condition to the nc alloy after HPT through 2 turns, thereby demonstrating a preservation of plasticity in the HEA. In addition, a calculation of the activation volume suggested that the grain boundaries play an important role in the plastic deformation of the nc HEA where the flow mechanism is consistent with other nc metals. Transmission electron microscopy showed that, unlike conventional fcc nc metals, the nc HEA exhibits excellent microstructural stability under severe stress conditions.

In this study, we obtain true stress–strain (SS) curves for a sheet specimen under consideration of local necking and material anisotropy. We first extract the SS curve up to the diffuse necking point from the tensile test load–displacement data. The curve's part after the onset of diffuse necking is extrapolated by the weighted-average method proposed by Ling [Y. Ling, AMP J. Technol. 5, 37–48 (1996)]. Initiation of local necking is predicted by means of the minor-to-major strain ratio in the specimen's center. We propose a criterion to determine the strain ratio at the onset of local necking and the major strain corresponding to the strain ratio at local necking. We complete the true SS curve by cutting off the SS curve at the major strains corresponding to the local necking or apparent fracture point. Finally, the effects of material anisotropy on SS curves are discussed.

Sesame (Sesamum indicum L.) is one of the oldest oil crops and is widely cultivated in Asia and Africa. The aim of this study was to assess the genetic diversity, phylogenetic relationships and population structure of 277 sesame core collection accessions collected from 15 countries in four different continents. A total of 158 alleles were detected among the sesame accessions, with the number varying from 3 to 25 alleles per locus and an average of 11.3. Polymorphism information content values ranged from 0.34 to 0.84, with an average of 0.568. These values indicated a high genetic diversity at 14 loci both among and within the populations. Of these, 44 genotype-specific alleles were identified in 12 of the 14 polymorphic simple sequence repeat markers. The core collection preserved a much higher level of genetic variation. Therefore, 10.1% was selected as the best sampling percentage from the whole collection when constructing the core collection. The 277 core collection accessions formed four robust clusters in the unweighted pair group method and the arithmetic averages (UPGMA) dendrogram, although the clustering did not indicate any clear division among the sesame accessions based on their geographical locations. Similar patterns were obtained using model-based structure analysis and country-based dendrograms, as some accessions situated geographically far apart were grouped together in the same cluster. The results of these analyses will increase our understanding of the genotype-specific alleles, genetic diversity and population structure of core collections, and the information can be used for the development of a future breeding strategy to improve sesame yield.

Using stellar population synthesis techniques, we explore the photometric signatures of white dwarf progenitor dominated galactic halos, in order to constrain the fraction of halo mass that may be locked up in white dwarf stellar remnants. We first construct a 109 M⊙ stellar halo using the canonical Salpeter initial stellar mass distribution, and then allow for an additional component of low- and intermediate-mass stars, which ultimately give rise to white dwarf remnants. Microlensing observations towards the Large Magellanic Cloud, coupled with several ground-based proper motion surveys, have led to claims that in excess of 20% of the dynamical mass of the halo (1012 M⊙) might be found in white dwarfs. Our results indicate that (1) even if only 1% of the dynamical mass of the dark halo today could be attributed to white dwarfs, their main sequence progenitors at high redshift (z ≈ 3) would have resulted in halos more than 100 times more luminous than those expected from conventional initial mass functions alone, and (2) any putative halo white dwarf progenitor dominated initial mass function component, regardless of its dynamical importance, would be virtually impossible to detect at the present day, due to its extremely faint surface brightness.

The primary present-day observables upon which theories of galaxy evolution are based are a system’s morphology, dynamics, colour, and chemistry. Individually, each provides an important constraint to any given model; in concert, the four represent a fundamental (intractable) boundary condition for chemodynamical simulations. We review the current state-of-the-art semi-analytical and chemodynamical models for the Milky Way, emphasising the strengths and weaknesses of both approaches.

We present the results of near-infrared (NIR) imaging and spectroscopic observations of the Galactic supernova remnant Cassiopeia A (Cas A). Applying the method of Principal Component Analysis to our broadband NIR spectra, we identify a total of 61 NIR emission knots of Cas A and classify them into three groups of distinct spectral characteristics: Helium-rich, Sulfur-rich, and Iron-rich groups. The first and second groups are of the circumstellar and supernova ejecta origin, respectively. The third group, which has enhanced iron emission, is of particular interests since it shows intermediate characteristics between the former two groups. We suggest that the Iron-rich group is knots of swept-up circumstellar medium around the contact discontinuity in Cas A and/or supernova ejecta from deep layers of its progenitor star which have recently encountered a reverse shock in the remnant.

We report the preliminary results for the detection of H2 and [Fe II] line features around the Galactic supernova remnants (SNRs) from the UWISH2 and UWIFE surveys that cover the first galactic quadrant of 7°<l<65° and |b|<1.3°. By this time, we have found a total of 17 H2-emitting and 14 [Fe II]-emitting SNRs in the coverage, and more than a half of them are detected in both H2 and [Fe II] emissions, which implies that the environment of these SNRs might be complex and composed of multi-phase medium. In this paper, we present our identification strategy and some preliminary results including H2 and [Fe II] luminosity distributions.

The surface brightness fluctuation (SBF) method at near-infrared (NIR) wavelengths is a powerful tool for estimating distances to unresolved stellar systems with high precision. The IR channel of the Wide Field Camera 3 (WFC3), installed on board the Hubble Space Telescope (HST) in 2009, has a greater sensitivity and a wider field of view than the previous generation of HST IR instruments, making it much more efficient for measuring distances to early-type galaxies in the Local Volume. To take full advantage of its capabilities, we need to empirically calibrate the SBF distance method for WFC3's NIR passbands. We present the SBF measurements for the WFC3/IR F160W bandpass filter using observations of 16 early-type galaxies in the Fornax and Virgo Clusters. These have been combined with existing (g475–z850) color measurements from the Advanced Camera for Surveys Virgo and Fornax Cluster Surveys to derive a space-based H160-band SBF relation as a function of color. We have also compared the absolute SBF magnitudes to those predicted by evolutionary population synthesis models in order to study stellar population properties in the target galaxies.

The numerical approach of Lee et al. [Trans. Korean Soc. Mech. Eng., A28, 816–825 (2004)] to spherical indentation technique for property evaluation of hyperelastic rubber is enhanced. The Yeoh model is adopted as the constitutive form of rubber material because it can express well large deformation and cover various deformation modes with a simple form. We first determine the friction coefficient between a rubber specimen and a spherical indenter in a practical viewpoint and perform finite element simulations for a deeper indentation depth than that selected by Lee et al. [Trans. Korean Soc. Mech. Eng., A28, 816–825 (2004)]. An optimal data acquisition spot is selected, which features sufficiently large strain energy density and negligible frictional effect. We improve then two normalized functions mapping an indentation load–displacement curve onto a strain energy density–invariant curve, the latter of which gives the Yeoh model constants. The enhanced spherical indentation approach successfully produces the rubber material properties with an average error of less than 5%. The validity of our developed approach is verified by experimental evaluation of material properties with three kinds of rubber materials.

The purpose of this study was to investigate whether there is any association between preeclampsia and eNOS, DDAH, and VEGF gene polymorphisms, and also to search for a possible association between haplotypes in eNOS, DDHA, and VEGF genes and the risk for preeclampsia. DNA was extracted from whole blood of 223 preeclampsia patients and 237 healthy pregnant women. The genotypes were analyzed by a single base primer extension assay using a SNaPShot assay kit. Results were analyzed with the Student's t-test, Chi-square test, and Logistic regression analysis. Haplotype analyses were performed using Haploview 3.2 version. There were no significant differences in genotype or allele frequencies of eNOS, DDAH, and VEGF gene polymorphisms between preeclampsia patients and controls. No increase in the risk of preeclampsia for those genes was observed under any model of inheritance and there were no statistically significant associations between any haplotypes and preeclampsia risk. Polymorphisms in eNOS, DDAH, and VEGF gene do not seem to be risk factors for preeclampsia.

We performed this study to investigate the effect of histone deacetylase inhibition during extended culture of in vitro matured mouse oocytes. In vitro matured mouse (BDF1) oocytes were cultured in vitro for 6, 12, and 24 h, respectively, and then inseminated. During in vitro culture for 6 and 12 h, two doses of trichostatin A (TSA), a histone deacetylase inhibitor, were added (100 nM and 500 nM) to the culture medium and the oocytes were then inseminated. During the 24-h in vitro culture, two doses of TSA were added (100 nM and 500 nM) to the medium and the oocytes were activated with 10 mM SrCl2. After the 6-h culture, the fertilization rate was similar to that of the control group, but the blastocyst formation rate was significantly decreased. After the 12-h culture, both the fertilization and blastocyst formation rates were significantly decreased. After the 24-h culture, total fertilization failure occurred. In the oocytes cultured for 6 and 12 h, the fertilization and blastocyst formation rates did not differ between the TSA-supplemented and control groups. Although extended culture of the mouse oocytes significantly affected their fertilization and embryo development, TSA supplementation did not overcome their decreased developmental potential.

Stream restoration is an important process affecting the ecological health of stream ecosystems. There have been numerous cases of restoration, dealing with either structural or biological changes. In Korea, most restoration projects have merely dealt with improving hydrological characteristics or water quality; however, in recent years the improvement of ecological characteristics has been an increasing focus for restoration projects. In this study, we utilized data collected from 5675 stream sites in May 2007 to discover general patterns of anthropogenic modification in Korean streams. The survey results after application of the stream modification index (SMI; presence or absence type; high scores indicate more disturbed) provided a general distribution of disturbed/undisturbed streams or rivers in the watershed. We then compared the level of modification with the socio-geographical patterns (population, land coverage, elevation, and slope) for the watershed. The results show that streams in highly populated areas suffered from human modification compared with other well-preserved stream sites. In metropolitan cities, urbanized areas had positive relationship as identified by a high SMI. On the other hand, agricultural land cover identified an SMI increase for lowland river area. In general, mountainous streams possessed a better status in stream morphology due to different land-cover patterns (i.e., mainly forested area); however, some mountainous areas were impacted by concentrated summer rainfall. We could distinguish the forcing variables (i.e., land use pattern) for the disturbed streams through a comparison between the SMI and geographical information; the SMI application was able to identify areas of high necessity for restoration.