38 research outputs found

    Partial ownership arrangements in the Japanese automobile industry; 1990-2000

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    The end of the 1990’s saw a number of foreign automobile manufacturers become the largest shareholders in several Japanese automobile manufacturers. It seems logical to conclude that a firm only enters into a partial ownership arrangement (POA) if it is profit maximizing. However, research to date has treated POAs as if exogenous to the model. This paper develops a model that assumes POAs are determined endogenously. Data for the Japanese automobile industry are then used to investigate the factors that determine whether a firm enters into a POA, and the effects a POA has on the price-cost margin. The findings of this paper suggest that while both foreign and domestic firms take an interest in product mix when exploring POAs in the Japanese market, they have differing profit incentives. Furthermore, the level of ownership has a positive effect on POAs.partial ownership arrangements, price-cost margin, technology transfers

    Topological isomers of human uroguanylin: interconversion between biologically active and inactive isomers

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    AbstractThe solution structures of the two compounds of human uroguanylin (I and II), which were generated during disulfide bond forming reaction, were found to be topological isomers by 1H-nuclear magnetic resonance spectroscopy. These isomers are interconvertible in aqueous media at rates which vary with the pH and temperature of the solution. Because compound I is active in the cGMP producing assay, but compound II is not, this interconversion may be useful for evaluating the activity of human uroguanylin both in vivo and in vitro

    Detections of [C II] 158 μ\mum and [O III] 88 μ\mum in a Local Lyman Continuum Emitter, Mrk 54, and its Implications to High-redshift ALMA Studies

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    We present integral field, far-infrared (FIR) spectroscopy of Mrk 54, a local Lyman Continuum Emitter (LCE), obtained with FIFI-LS on the Stratospheric Observatory for Infrared Astronomy. This is only the second time, after Haro 11, that [C II] 158 μ\mum and [O III] 88 μ\mum spectroscopy of the known LCEs have been obtained. We find that Mrk 54 has a strong [C II] emission that accounts for 1\sim1% of the total FIR luminosity, whereas it has only moderate [O III] emission, resulting in the low [O III]/[C II] luminosity ratio of 0.22±0.060.22\pm0.06. In order to investigate whether [O III]/[C II] is a useful tracer of fescf_{\rm esc} (LyC escape fraction), we examine the correlations of [O III]/[C II] and (i) the optical line ratio of O32\rm O_{32} \equiv [O III] 5007 \AA/[O II] 3727 \AA, (ii) specific star formation rate, (iii) [O III] 88 μ\mum/[O I] 63 μ\mum ratio, (iv) gas phase metallicity, and (v) dust temperature based on a combined sample of Mrk 54 and the literature data from the Herschel Dwarf Galaxy Survey and the LITTLE THINGS Survey. We find that galaxies with high [O III]/[C II] luminosity ratios could be the result of high ionization (traced by O32\rm O_{32}), bursty star formation, high ionized-to-neutral gas volume filling factors (traced by [O III] 88 μ\mum/[O I] 63 μ\mum), and low gas-phase metallicities, which is in agreement with theoretical predictions. We present an empirical relation between the [O III]/[C II] ratio and fescf_{\rm esc} based on the combination of the [O III]/[C II] and O32\rm O_{32} correlation, and the known relation between O32\rm O_{32} and fescf_{\rm esc}. The relation implies that high-redshift galaxies with high [O III]/[C II] ratios revealed by ALMA may have fesc0.1f_{\rm esc}\gtrsim0.1, significantly contributing to the cosmic reionization.Comment: 14 pages, 5 figures, Accepted for publication in Ap

    Paleoclimatic and paleoceanographic records through Marine Isotope Stage 19 at the Chiba composite section, central Japan: A key reference for the EarlyeMiddle Pleistocene Subseries boundary

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    Marine Isotope Stage (MIS) 19 is an important analogue for the present interglacial because of its similar orbital configuration, especially the phasing of the obliquity maximum to precession minimum. However, sedimentary records suitable for capturing both terrestrial and marine environmental changes are limited, and thus the climatic forcing mechanisms for MIS 19 are still largely unknown. The Chiba composite section, east-central Japanese archipelago, is a continuous and expanded marine sedimentary succession well suited to capture terrestrial and marine environmental changes through MIS 19. In this study, a detailed oxygen isotope chronology is established from late MIS 20 to early MIS 18, supported by a U-Pb zircon age and the presence of the Matuyama–Brunhes boundary. New pollen, marine microfossil, and planktonic foraminiferal δ18O and Mg/Ca paleotemperature records reveal the complex interplay of climatic influences. Our pollen data suggest that the duration of full interglacial conditions during MIS 19 extends from 785.0 to 775.1 ka (9.9 kyr), which offers an important natural baseline in predicting the duration of the present interglacial. A Younger Dryas-type cooling event is present during Termination IX, suggesting that such events are linked to this orbital configuration. Millennial- to multi-millennial-scale variations in our δ18O and Mg/Ca records imply that the Subarctic Front fluctuated in the northwestern Pacific Ocean during late MIS 19, probably in response to East Asian winter monsoon variability. The climatic setting at this time appears to be related to less severe summer insolation minima at 65˚N and/or high winter insolation at 50˚N. Our records do not support a recently hypothesized direct coupling between variations in the geomagnetic field intensity and global/regional climate change. Our highly resolved paleoclimatic and paleoceanographic records, coupled with a well-defined Matuyama–Brunhes boundary (772.9 ka; duration 1.9 kyr), establish the Chiba composite section as an exceptional climatic and chronological reference section for the Early–Middle Pleistocene boundary.ArticleQuaternary Science Reviews 191: 406-430(2018)journal articl

    Complex Epistasis for Dobzhansky–Muller Hybrid Incompatibility in Solanum

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    We examined the prevalence of interactions between pairs of short chromosomal regions from one species (Solanum habrochaites) co-introgressed into a heterospecific genetic background (Solanum lycopersicum). Of 105 double introgression line (DIL) families generated from a complete diallele combination of 15 chromosomal segments, 39 (∼38%) showed evidence for complex epistasis in the form of genotypic and/or allelic marker transmission distortion in DIL F2 populations

    Comparative Genetics of Hybrid Incompatibility: Sterility in Two Solanum Species Crosses

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    The genetic basis of hybrid sterility can provide insight into the genetic and evolutionary origins of species barriers. We examine the genetics of hybrid incompatibility between two diploid plant species in the plant clade Solanum sect. Lycopersicon. Using a set of near-isogenic lines (NILs) representing the wild species Solanum pennellii (formerly Lycopersicon pennellii) in the genetic background of the cultivated tomato S. lycopersicum (formerly L. esculentum), we found that hybrid pollen and seed infertility are each based on a modest number of loci, male (pollen) and other (seed) incompatibility factors are roughly comparable in number, and seed-infertility QTL act additively or recessively. These findings are remarkably consistent with our previous analysis in a different species pair, S. lycopersicum × S. habrochaites. Data from both studies contrast strongly with data from Drosophila. Finally, QTL for pollen and seed sterility from the two Solanum studies were chromosomally colocalized, indicating a shared evolutionary history for these QTL, a nonrandom genomic distribution of loci causing sterility, and/or a proclivity of certain genes to be involved in hybrid sterility. We show that comparative mapping data can delimit the probable timing of evolution of detected QTL and discern which sterility loci likely evolved earliest among species

    A comparative study of ribosomal proteins: Linkage between amino acid distribution and ribosomal assembly

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    Background: Assembly of the ribosome from its protein and RNA constituents must occur quickly and efficiently in order to synthesize the proteins necessary for all cellular activity. Since the early 1960\u27s, certain characteristics of possible assembly pathways have been elucidated, yet the mechanisms that govern the precise recognition events remain unclear. We utilize a comparative analysis to investigate the amino acid composition of ribosomal proteins (r-proteins) with respect to their role in the assembly process. We compared small subunit (30S) r-protein sequences to those of other housekeeping proteins from 560 bacterial species and searched for correlations between r-protein amino acid content and factors such as assembly binding order, environmental growth temperature, protein size, and contact with ribosomal RNA (rRNA) in the 30S complex. Results: We find r-proteins have a significantly high percent of positive residues, which are highly represented at rRNA contact sites. An inverse correlation between the percent of positive residues and r-protein size was identified and is mainly due to the content of Lysine residues, rather than Arginine. Nearly all r-proteins carry a net positive charge, but no statistical correlation between the net charge and the binding order was detected. Thermophilic (high-temperature) r-proteins contain increased Arginine, Isoleucine, and Tyrosine, and decreased Serine and Threonine compared to mesophilic (lower-temperature), reflecting a known distinction between thermophiles and mesophiles, possibly to account for protein thermostability. However, this difference in amino acid content does not extend to rRNA contact sites, as the proportions of thermophilic and mesophilic contact residues are not significantly different. Conclusions: Given the significantly higher level of positively charged residues in r-proteins and at contact sites, we conclude that ribosome assembly relies heavily on an electrostatic component of interaction. However, the binding order of r-proteins in assembly does not appear to depend on these electrostatics interactions. Additionally, because thermophiles and mesophiles exhibit significantly different amino acid compositions in their sequences but not in the identities of contact sites, we conclude that this electrostatic component of interaction is insensitive to temperature and is not the determining factor differentiating the temperature sensitivity of ribosome assembly

    Ecological and geographic modes of species divergence in wild tomatoes

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    Understanding the role of geography and ecology in species divergence is central to the study of evolutionary diversification. We used climatic, geographic, and biological data from nine wild Andean tomato species to describe each species' ecological niche and to evaluate the likely ecological and geographical modes of speciation in this clade. Using data from > 1000 wild accessions and publicly available data derived from geographic information systems for various environmental variables, we found most species pairs were significantly differentiated for one or more environmental variables. By comparing species' predicted niches generated by species distribution modeling (SDM), we found significant niche differentiation among three of four sister- species pairs, suggesting ecological divergence is consistently associated with recent divergence. In comparison, based on age- range correlation (ARC) analysis, there was no evidence for a predominant geographical (allopatric vs. sympatric) context for speciation in this group. Overall, our results suggest an important role for environmentally mediated differentiation, rather than simply geographical isolation, in species divergence.14 page(s
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