Hybrid rice is the dominant form of rice planted in China, and its use has extended worldwide since the 1970s. It offers great yield advantages and has contributed greatly to the world’s food security. However, the molecular mechanisms underlying heterosis have remained a mystery. In this study we integrated genetics and omics analyses to determine the candidate genes for yield heterosis in a model two-line rice hybrid system, Liang-you-pei 9 (LYP9) and its parents. Phenomics study revealed that the better parent heterosis (BPH) of yield in hybrid is not ascribed to BPH of all the yield components but is specific to the BPH of spikelet number per panicle (SPP) and paternal parent heterosis (PPH) of effective panicle number (EPN). Genetic analyses then identified multiple quantitative trait loci (QTLs) for these two components. Moreover, a number of differentially expressed genes and alleles in the hybrid were mapped by transcriptome profiling to the QTL regions as possible candidate genes. In parallel, a major QTL for yield heterosis, rice heterosis 8 (RH8), was found to be the DTH8/Ghd8/LHD1 gene. Based on the shared allelic heterozygosity of RH8 in many hybrid rice cultivars, a common mechanism for yield heterosis in the present commercial hybrid rice is proposed.

Abstract-A compact hyper-band (> 10:1 impedance bandwidth) printed antenna design is investigated numerically and experimentally. It is based on an elliptical-slot antenna augmented with a parasitic oval patch and driven with a specially engineered microstrip-line-fed elliptical tuning fork element. The parasitic and driven elements are adjusted along with the elliptical slot to create additional resonance modes; adjust the coupling strengths among all of the design components; facilitate the overlap of adjacent resonance modes; and fine tune the input impedance. The total size of the final optimized antenna is only 30 × 40 mm 2 . It exhibits a 10-dB impedance bandwidth from 2.26 to 22.18 GHz. Desirable radiation performance characteristics, including relatively stable and omni-directional radiation patterns, are obtained over this range. A prototype was fabricated and tested. The experimental results confirm the predicted input impedance bandwidth and radiation characteristics. While the hyper-band performance could be used for high fidelity short pulse applications, the antenna could also be used for multi-band operations from 3.110.6 GHz since it covers that entire ultra-wideband (UWB) spectral range. Index Terms-Compact antennas, hyper-band, parasitic elements, printed slot antennas, ultra-wideband antenna

A compact planar ultra-wideband (UWB) antenna with continuously tunable, independent band-notches for cognitive radio applications is presented. The antenna is fabricated using a copper cladded substrate. A radiating patch with an inverted rectangular T-slot is etched on the top side of the substrate. A straight rectangular strip with a complete gap is embedded into the T-slot. By placing a single varactor diode across this gap, a frequency-agile band-notch function below 5 GHz is realized. On the bottom side of substrate, a U-shaped parasitic element having an interdigitated-structure is placed beneath the radiating patch. The second narrow band-notch is created by inserting a second varactor diode into the gap on one leg of the parasitic element. It has a frequency agile performance above 5 GHz. The presence of the interdigitated structure suppresses higher-order resonant modes and enhances the tunability of the notched bandwidth. Because these antenna structures naturally block DC, a very small number of lumped elements are required. The experimental results, which are in good agreement with their simulated values, demonstrate that both band-notches can be independently controlled and the entire frequency-agile fractional bandwidth is as high as 74.5 %, demonstrating a very wide notched frequency-agile coverage. Index Terms-Band-notch filters, frequency agile, frequency tunable, planar antennas, UWB antennas I. INTRODUCTION ltra-wideband (UWB) technology has been widely applied in wireless sensor networks, biomedical and healthcare wireless systems, and some other in-house devices in radar detecting, locating, and communications [1]. These applications benefit from the unique features of low-power spectral density and consumption associated with UWB

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