catena-Poly[[bis­(4-methyl­benzene­thiol­ato)cadium(II)]-μ-1,3-di-4-pyridylpropane]

In the title compound, [Cd(C7H7S)2(C13H14N2)]n, the unique CdII ion, located on a twofold rotation axis, is coordinated by two S atoms and two N atoms in a slightly distorted tetra­hedral environment. Symmetry-related CdII ions are linked via bridging 1,3-di-4-pyridylpropane ligands, forming a zig-zag chain-structure parallel to [001]. In the crystal structure, there are weak intra­chain π–π stacking inter­actions between benzene rings, with a centroid–centroid distance of 3.825 (7) Å, and pairs of chains are inter­digitated with respect to the 4-methyl­benzene­thiol­ate groups

Refinement and Validation of a Real-time Airborne System for Remotely Sensing Ocean Surface using Communication Satellite Signals

The ability to remotely sense ocean wave heights and wind speed by measuring the reflected Radio Frequency (RF) signals from the ocean’s surface has been demonstrated in previous research projects. The recording systems for these research projects collected and stored unmodified RF signals and then analyzed the data through post-processing. Several disadvantages to this approach include large requirements for data storage and lengthy post-processing time. To assist in the creation of a suitable platform for an airplane-based application, a new system was designed which features real-time processing of the RF signals. This system captures two RF signals in the 2.4 GHz regions (direct and reflected), calculates the cross-correlation between the two signals and then outputs the result to a PC. Due to the time-consuming nature of the cross-correlation algorithm, a FPGA based implementation of the system was chosen to conform to the real-time constraints of the system. In this project, previously created Verilog source code for the system was debugged, improved and verified. This project also developed a method to test the system by using several 110-foot sections of RG6 Coaxial Cables. These cables induced a physical delay in the reflected channel, simulating the application’s conditions, in order to cause a shift in the correlation peak. The results are discussed as well as suggestions for future improvements

Ocean Wind Speed Measurement Using Wideband GNSS-R Signals

The use of Global Navigation Satellite System-Reflectometry (GNSS-R) for remote sensing of ocean wind speeds has been explored for nearly two decades and has become an important passive remote sensing technique for verification of hurricane formation models. To obtain wind speed measurements, reflected GNSS signals are first cross-correlated with locally generated copies to construct delay-doppler maps (DDMs). Through statistical models, DDMs can provide information about the mean-square slope (MSS) of the ocean surface, which is related to wind speed. Previous studies have focused on legacy signals such as GPS L1. However, it is expected that the MSS relationship with ocean wind field can be better understood by using similar methods with wider bandwidth signals, such as the GPS L5 or Galileo E5 signals. For this research purpose, a prototype data collection system was developed to handle the necessary data sampling speeds for the L5 and E5 signals. This system used a Universal Software Radio Peripheral X300 device configured to sample at 100 MHz. A receiver was designed to generate DDMs with the L5 signal through zero-padded FFT techniques for cross-correlations. Lab tests showed that the resulting DDMs have the proper sinc function behavior with respect to doppler frequency and triangle function behavior to time delay. For future field experiments, data will be obtained by mounting the prototype system to the National Oceanic and Atmospheric Administration (NOAA) Hurricane Hunter aircraft during the 2017 hurricane season, and wind speed retrieval will be performed by analyzing the DDMs generated by the receiver

A transgenic system for generation of transposon Ac/Ds-induced chromosome rearrangements in rice

The maize Activator (Ac)/Dissociation (Ds) transposable element system has been used in a variety of plants for insertional mutagenesis. Ac/Ds elements can also generate genome rearrangements via alternative transposition reactions which involve the termini of closely linked transposons. Here, we introduced a transgene containing reverse-oriented Ac/Ds termini together with an Ac transposase gene into rice (Oryza sativa ssp. japonica cv. Nipponbare). Among the transgenic progeny, we identified and characterized 25 independent genome rearrangements at three different chromosomal loci. The rearrangements include chromosomal deletions and inversions and one translocation. Most of the deletions occurred within the T-DNA region, but two cases showed the loss of 72 kilobase pairs (kb) and 79 kb of rice genomic DNA flanking the transgene. In addition to deletions, we obtained chromosomal inversions ranging in size from less than 10 kb (within the transgene DNA) to over 1 million base pairs (Mb). For 11 inversions, we cloned and sequenced both inversion breakpoints; in all 11 cases, the inversion junctions contained the typical 8 base pairs (bp) Ac/Ds target site duplications, confirming their origin as transposition products. Together, our results indicate that alternative Ac/Ds transposition can be an efficient tool for functional genomics and chromosomal manipulation in rice

Midwest Crop Farmers’ Perceptions of the U.S.-China Trade War

The trade dispute between the United States and China that began in 2018 quickly reached an unprecedented level. As of June 2019, several rounds of talks failed to prevent the United States from imposing tariffs on more than $250 billion worth of Chinese products

Convergent sequence evolution between echolocating bats and dolphins

SummaryCases of convergent evolution — where different lineages have evolved similar traits independently — are common and have proven central to our understanding of selection. Yet convincing examples of adaptive convergence at the sequence level are exceptionally rare [1]. The motor protein Prestin is expressed in mammalian outer hair cells (OHCs) and is thought to confer high frequency sensitivity and selectivity in the mammalian auditory system [2]. We previously reported that the Prestin gene has undergone sequence convergence among unrelated lineages of echolocating bat [3]. Here we report that this gene has also undergone convergent amino acid substitutions in echolocating dolphins, which group with echolocating bats in a phylogenetic tree of Prestin. Furthermore, we find evidence that these changes were driven by natural selection