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Viewing investment projects in new technologies as real options, this paper studies the effects ofendogenous competition and asymmetric information on the strategic exercise of real options. We firstdevelop a multi-period, game-theoretic model and show how competition leads to early exercise andaggressive investment behaviors and how competition erodes option values. We then relax the typicalfull-information assumption found in the literature and allow information asymmetry to exist acrossfirms. Our model shows, in contrast to the literature that payoff is independent of the ordering ofexercise, that the sequential exercise of real options may generate both informational and payoffexternalities. We also find some surpising but interesting results such as having more information isnot necessarily better. 相似文献
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Speliotes EK Willer CJ Berndt SI Monda KL Thorleifsson G Jackson AU Lango Allen H Lindgren CM Luan J Mägi R Randall JC Vedantam S Winkler TW Qi L Workalemahu T Heid IM Steinthorsdottir V Stringham HM Weedon MN Wheeler E Wood AR Ferreira T Weyant RJ Segrè AV Estrada K Liang L Nemesh J Park JH Gustafsson S Kilpeläinen TO Yang J Bouatia-Naji N Esko T Feitosa MF Kutalik Z Mangino M Raychaudhuri S Scherag A Smith AV Welch R Zhao JH Aben KK Absher DM Amin N Dixon AL Fisher E Glazer NL Goddard ME 《Nature genetics》2010,42(11):937-948
Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ~ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10??), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation. 相似文献
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Hundreds of variants clustered in genomic loci and biological pathways affect human height 总被引:2,自引:0,他引:2
Lango Allen H Estrada K Lettre G Berndt SI Weedon MN Rivadeneira F Willer CJ Jackson AU Vedantam S Raychaudhuri S Ferreira T Wood AR Weyant RJ Segrè AV Speliotes EK Wheeler E Soranzo N Park JH Yang J Gudbjartsson D Heard-Costa NL Randall JC Qi L Vernon Smith A Mägi R Pastinen T Liang L Heid IM Luan J Thorleifsson G Winkler TW Goddard ME Sin Lo K Palmer C Workalemahu T Aulchenko YS Johansson A Zillikens MC Feitosa MF Esko T Johnson T Ketkar S Kraft P Mangino M Prokopenko I Absher D Albrecht E 《Nature》2010,467(7317):832-838
Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P?0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways. 相似文献
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