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Allopolyploidy involves hybridization and duplication of divergent parental genomes and provides new avenues for gene expression. The expression levels of duplicated genes in polyploids can show deviation from parental additivity (the arithmetic average of the parental expression levels). Nonadditive expression has been widely observed in diverse polyploids and comprises at least three possible scenarios: (a) The total gene expression level in a polyploid is similar to that of one of its parents (expression-level dominance); (b) total gene expression is lower or higher than in both parents (transgressive expression); and (c) the relative contribution of the parental copies (homeologs) to the total gene expression is unequal (homeolog expression bias). Several factors may result in expression nonadditivity in polyploids, including maternal-paternal influence, gene dosage balance, cis- and/or transregulatory networks, and epigenetic regulation. As our understanding of nonadditive gene expression in polyploids remains limited, a new generation of investigators should explore additional phenomena (i.e., alternative splicing) and use odier high-throughput "omics" technologies to measure the impact of nonadditive expression on phenotype, proteome, and metabolome. [ABSTRACT FROM AUTHOR]

Nearly four decades ago, Roose & Gottlieb (Roose & Gottlieb 1976 Evolution 30, 818-830. (doi:10.2307/2407821)) showed that the recently derived allotetraploids Tragopogon mirus and T. miscellus combined the allozyme profiles of their diploid parents (T. dubius and T. porrifolius,a n d T. dubius and T. pratensis, respectively). This classic paper addressed the link between genotype and biochemical phenotype and documented enzyme additivity in allopolyploids. Perhaps more important than their model of additivity, however, was their demonstration of novelty at the biochemical level. Enzyme multiplicity--the production of novel enzyme forms in the allopolyploids--can provide an extensive array of polymorphism for a polyploid individual and may explain, for example, the expanded ranges of polyploids relative to their diploid progenitors. In this paper, we extend the concept of evolutionary novelty in allopolyploids to a range of genetic and ecological features. We observe that the dynamic nature of polyploid genomes--with alterations in gene content, gene number, gene arrangement, gene expression and transposon activity--may generate sufficient novelty that every individual in a polyploid population or species may be unique. Whereas certain combinations of these features will undoubtedly be maladaptive, some unique combinations of newly generated variation may provide tremendous evolutionary potential and adaptive capabilities. [ABSTRACT FROM AUTHOR]

The effect of the size of the B powder and the Mg powder on MgB2 phase formation has been studied by the technique of in situ high-temperature resistivity (HT-r(T)) measurement. Two characteristic temperatures indicating the phase formation, the onset point, Tonset, and the completion point, TPF, were directly determined during the continuous heating process. These two temperatures of the samples synthesized using nanometer-size B powder (Nano-B) and micrometer-size B powder (Micro-B) with nanometer-size Mg (Nano-Mg) are almost the same, i.e. Tonset = 713 K and TPF[?]763 K, respectively, indicating that the phase formation temperature of MgB2 does not primarily depend on the particle size of the B powder. A similar process was then carried out on Mg powders with the same B powder. An exponential relationship between the onset phase formation temperature and the Mg powder size is clearly shown, which can be fully fitted by a modulated diffusion equation and which gives Q = 421 kJ mol[?]1 describing the grain boundary activation energy of Mg diffusing into B. We also find that the MgB2 crystallites along the [101] direction have the lowest formation energy, revealed by x-ray diffraction (XRD) analysis on raw Mg powders, and the corresponding MgB2 crystallites aligned along [101] will be formed preferentially in the sintering process. This result is useful for the understanding of MgB2 phase formation in the solid reaction process. [ABSTRACT FROM AUTHOR]

Background: There have been considerable changes in breastfeeding practices in China over the past forty years. However China is a very large country, and breastfeeding rates in different parts of China vary considerably. The objective of this paper is to identify and compare breastfeeding types and rates between 1994-1996 and 2003-2004 in Shihezi, Xinjiang Uygur Autonomous Region, PR China. Methods: In 1994-1996, a study of breastfeeding (n = 2197) was undertaken in Shihezi, Xinjiang, PR China. A decade later in 2003-2004, a longitudinal study (n = 545) of infant feeding practices was undertaken in the same area. Results: The 'any breastfeeding' rates at 1, 4 and 6 months were 94%, 82% and 78% respectively in the early 1990s. A decade later, breastfeeding at 1 month was lower, but rates at 4 and 6 months remained the same. In 2004 the 'full breastfeeding' rate at one month was significantly higher (57%) than a decade earlier (38%), but after 3 months there was a rapid decline. This reflected a shift in the way complementary foods are introduced: the initial introduction was later, but by a higher proportion of mothers. Conclusion: The rate of breastfeeding at one month is significantly lower in 2003-2004 when compared to 1994-1996. The 'full breastfeeding' rates were initially higher, but after 3 months were then lower. The Chinese national breastfeeding targets were not reached in either period of the study. These studies show the need to further promote full or exclusive breastfeeding and further longitudinal studies are necessary to provide the detailed knowledge about risk factors required for health promotion programs. [ABSTRACT FROM AUTHOR]

In this paper, ground-signal-ground type through-silicon vias (TSVs) exploiting air gaps as insulation layers are designed, analyzed and simulated for applications in millimeter wave. The compact wideband equivalent-circuit model and passive elements (RLGC) parameters based on the physical parameters are presented with the frequency up to 100 GHz. The parasitic capacitance of TSVs can be approximated as the dielectric capacitance of air gaps when the thickness of air gaps is greater than 0.75 μm. Therefore, the applied voltage of TSVs only needs to achieve the flatband voltage, and there is no need to indicate the threshold voltage. This is due to the small permittivity of air gaps. The proposed model shows good agreement with the simulation results of ADS and Ansoft’s HFSS over a wide frequency range. [ABSTRACT FROM AUTHOR]

We demonstrate coherent control of population transfer between vibrational states in an optical lattice by using interference between a one-phonon transition at 2ω and a two-phonon transition at ω. The co and 2ω transitions are driven by phase- and amplitude-modulation of the lattice laser beams, respectively. By varying the relative phase of these two pathways, we control the branching ratio between transitions to the first excited state and those to the higher states. Our best result shows a branching ratio of 17 ± 2, which is the highest among coherent control experiments using analogous schemes. Such quantum control techniques may find broad application in suppressing leakage errors in a variety of quantum information architectures. [ABSTRACT FROM AUTHOR]