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  • 1
    Language: English
    In: Science (New York, N.Y.), 24 October 2014, Vol.346(6208), pp.423-4
    Description: Unlike animals, plants have two alternating generations: a diploid sporophyte and a haploid gametophyte. Through meiosis, the sporophyte produces haploid spores, which then give rise to gametophytes, a multicellular haploid structure that produces gametes for sexual reproduction. All seed plants and some non-seed plants are heterosporous, producing spores of different sizes: large female spores and small male spores. Most ferns, on the other hand, are homosporous; they produce a single type of spore. After germination, each fern spore has the potential to develop into a male, female, or hermaphrodite gametophyte. The developmental decision that determines the sex of a particular gametophyte depends on an interplant communication system mediated by chemical signals, termed antheridiogens ( 1 , 2 ). On page 469 of this issue, Tanaka et al. ( 3 ) show that an antheridiogen in the Japanese climbing fern ( Lygodium japonicum ) functions as more than a simple chemical signal. Covalent modification of the antheridiogen is required to trigger the fern's response to form male gametophytes. Temporal and spatial separation of the biosynthetic pathway between the early- and late-maturing gametophytes ensures the production of the antheridiogen, and the active male-inducing chemically modified form, at just the right time and place.
    Keywords: Gametogenesis, Plant ; Ferns -- Cytology ; Gibberellins -- Biosynthesis ; Pheromones -- Physiology
    ISSN: 00368075
    E-ISSN: 1095-9203
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  • 2
    Language: English
    In: Journal of Applied Psychology, 2014, Vol.99(2), pp.351-359
    Description: This study extends the stress literature by exploring the relationship between family incivility and job performance. We examine whether psychological distress mediates the link between family incivility and job performance. We also investigate how core self-evaluation might moderate this mediated relationship. Data from a 2-wave study indicate that psychological distress mediates the relationship between family incivility and job performance. In addition, core self-evaluation moderates the relationship between family incivility and psychological distress but not the relationship between psychological distress and job performance. The results hold while controlling for general job stress, family-to-work conflict, and work-to-family conflict. The findings suggest that family incivility is linked to poor performance at work, and psychological distress and core self-evaluation are key mechanisms in the relationship.
    Keywords: Core Self-Evaluation ; Incivility ; Performance ; Psychological Well-Being ; Work–Family Conflict
    ISSN: 0021-9010
    E-ISSN: 1939-1854
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  • 3
    Language: English
    In: Archives of internal medicine, 11 June 2012, Vol.172(11), pp.845-6
    Keywords: Mortality, Premature ; Smoking Cessation ; Smoking -- Mortality
    ISSN: 00039926
    E-ISSN: 1538-3679
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  • 4
    Language: English
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, 01 January 2011, Vol.299(1-2), pp.197-199
    Description: The body mass of extinct animals have never been estimated from footprints, despite its potential utility. To redeem this situation, the relationship between body mass and the areas of footprints was derived from 17 species of modern tetrapods. Body mass of seven ichnospecies of pterosaur tracks were estimated, because pterosaur body weight is an intriguing topic with reference to their flying ability. Estimated body weights of pterosaurs range from 110 g to 145 kg. The result provides evidence that large pterosaurs are about 10 times heavier than the heaviest modern bird.
    Keywords: Body Weight ; Footprints ; Pterosaurs ; Geology
    ISSN: 0031-0182
    E-ISSN: 1872-616X
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  • 5
    Language: English
    In: Journal of the American Chemical Society, 01 February 2012, Vol.134(4), pp.2399-406
    Description: Pyrophosphate ion (PP(i)) release after nucleotide incorporation is a necessary step for RNA polymerase II (pol II) to enter the next nucleotide addition cycle during transcription elongation. However, the role of pol II residues in PP(i) release and the mechanistic relationship between PP(i) release and the conformational change of the trigger loop remain unclear. In this study, we constructed a Markov state model (MSM) from extensive all-atom molecular dynamics (MD) simulations in the explicit solvent to simulate the PP(i) release process along the pol II secondary channel. Our results show that the trigger loop has significantly larger intrinsic motion after catalysis and formation of PP(i), which in turn aids PP(i) release mainly through the hydrogen bonding between the trigger loop residue H1085 and the (Mg-PP(i))(2-) group. Once PP(i) leaves the active site, it adopts a hopping model through several highly conserved positively charged residues such as K752 and K619 to release from the pol II pore region of the secondary channel. These positive hopping sites form favorable interactions with PP(i) and generate four kinetically metastable states as identified by our MSM. Furthermore, our single-mutant simulations suggest that H1085 and K752 aid PP(i) exit from the active site after catalysis, whereas K619 facilitates its passage through the secondary channel. Finally, we suggest that PP(i) release could help the opening motion of the trigger loop, even though PP(i) release precedes full opening of the trigger loop due to faster PP(i) dynamics. Our simulations provide predictions to guide future experimental tests.
    Keywords: Molecular Dynamics Simulation ; Diphosphates -- Chemistry ; RNA Polymerase II -- Chemistry
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 6
    Language: English
    In: Current Biology, 10 May 2011, Vol.21(9), pp.R338-R345
    Description: Bioactive gibberellins (GAs) are diterpene phytohormones that modulate growth and development throughout the whole life cycle of the flowering plant. Impressive advances have been made in elucidating the GA pathway with the cloning and characterization of genes encoding most GA biosynthesis and catabolism enzymes, GA receptors (GIBBERELLIN INSENSITIVE DWARF1, GID1) and early GA signaling components. Recent biochemical, genetic and structural analyses demonstrate that GA de-represses its signaling pathway by GID1-induced degradation of DELLA proteins, which are master growth repressors, via a ubiquitin–proteasome pathway. Multiple endogenous signals and environmental cues also interact with the GA–GID1–DELLA regulatory module by affecting the expression of GA metabolism genes, and hence GA content and DELLA levels. Importantly, DELLA integrates different signaling activities by direct protein–protein interaction with multiple key regulatory proteins from other pathways. Comparative studies suggest that the functional GA–GID1–DELLA module is highly conserved among vascular plants, but not in the bryophytes. Interestingly, differentiation of the moss is regulated by as yet unidentified -kaurene-derived diterpenes, which are distinct from the common active GAs in vascular plants.
    Keywords: Biology
    ISSN: 0960-9822
    E-ISSN: 1879-0445
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  • 7
    Language: English
    In: Urban Studies, May 2013, Vol.50(6), pp.1148-1164
    Description: This paper focuses on a relatively overlooked aspect of social polarisation in Singapore, Hong Kong and Taipei: its gender implications. The transformation of these cities, from industrial to post-industrial cities, has been accompanied by a transition from Chinese patriarchal society to modern society. A dual gendered structure is emerging—a regime of labour intimacy (RLI) under state regulations and a technomuscular capitalism (TMC), presenting itself as a competitive labour market. Migrant workers are introduced to compensate for the loss of household labour, but the wage gap between them and their local counterparts may be controlled. The occupational segmentation and income disparity between men and women are improving because of the upgrade of women’s status. The model of bound RLIs and open TMCs emphasises a more contextually situated construction in which state migration policies and changing gender status play an intermediate role in the division of labour between work and home.
    Keywords: Sociology & Social History
    ISSN: 0042-0980
    E-ISSN: 1360-063X
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  • 8
    Language: English
    In: Journal of Substance Abuse Treatment, July 2012, Vol.43(1), pp.12-19
    Description: For reasons of safety and effectiveness, many forces in health care, especially the Affordable Care Act of 2010, are pressing for improved identification and management of substance use disorders within mainstream health care. Thus, standard information about patient substance use will have to be collected and used by providers within electronic health record systems (EHRS). Although there are many important technical, legal, and patient confidentiality issues that must be dealt with to achieve integration, this article focuses upon efforts by the National Institute on Drug Abuse and other federal agencies to develop a common set of core questions to screen, diagnose, and initiate treatment for substance use disorders as part of national EHRS. This article discusses the background and rationale for these efforts and presents the work to date to identify the questions and to promote information sharing among health care providers.
    Keywords: Substance Abuse ; Health Information ; Electronic Health Record System ; Patient Confidentiality ; Patient Safety ; Social Welfare & Social Work
    ISSN: 0740-5472
    E-ISSN: 1873-6483
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  • 9
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 08 July 2014, Vol.111(27), pp.E2778
    Description: Author contributions: H.-C.T. wrote the paper.
    Keywords: Sciences (General);
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 10
    Language: English
    In: Economic Journal, Sept, 2012, Vol.122, p.903(30)
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/j.1468-0297.2012.02518.x/abstract Byline: Wen-Tai Hsu(1) This article proposes a theory of city size distribution via a hierarchy approach rather than the popular random growth process. It does so by formalising central place theory using an equilibrium entry model and specifying the conditions under which city size distribution follows a power law. The force driving the city size differences in this model is the heterogeneity in economies of scale across goods. The city size distribution under a central place hierarchy exhibits a power law if the distribution of scale economies is regularly varying, which is a general class that encompasses many well-known, commonly used distributions. Author Affiliation: (1)National University of Singapore Article Note: (*) Corresponding author: Wen-Tai Hsu, Department of Economics, National University of Singapore, Faculty of Arts & Social Sciences, AS2 Level 6, 1 Arts Link, Singapore 117570. Email: wentai@nus.edu.sg. ([dagger]) This article was previously circulated under the title 'Central Place Theory and Zipf's Law'. I am grateful to Tom Holmes, Sam Kortum and Erzo G. J. Luttmer for their advice and continuous support. For their helpful comments, I thank Marcus Berliant, V.V. Chari, Jiahua Che, Gilles Duranton, Jan Eeckhout, Masa Fujita, Xavier Gabaix, Luis Garicano, Yannis Ioannides, Patrick Kehoe, James Mirrlees, Tomoya Mori, Roger Myerson, Derek Neal, Shi Qi, Esteban Rossi-Hansberg, Maryam Saeedi, Robert Shimer, Tony E. Smith, Takatoshi Tabuchi, Matthew Turner, Harald Uhlig, Ping Wang, William Wheaton, two anonymous referees, and the seminar participants at University of Minnesota, Federal Reserve Bank of Minneapolis, University of Chicago, University of Toronto, Kyoto University, National Graduate Institute for Policy Studies, City University of Hong Kong, Chinese University of Hong Kong, Fudan University, the 2008 Annual Meeting of the American Real Estate and Urban Economics Association, the EITSS conference of Nagoya University, and the 2009 Meeting of the Urban Economics Association. All errors are mine. Submitted: 6 January 2011 Accepted: 12 November 2011
    Keywords: Universities And Colleges -- Analysis
    ISSN: 0013-0133
    Source: Cengage Learning, Inc.
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