Study on probabilistic model building genetic network programming

制度:新 ; 報告番号:甲3776号 ; 学位の種類:博士(工学) ; 授与年月日:2013/3/15 ; 早大学位記番号:新6149Waseda Universit

Peer Priming? A Large-Scale Field Experiment Studying the Impact of Popular Rankings on Demand in Mobile Retail

Consumers on mobile retail apps face significant search costs due to the small screen size of devices. One of the search aid features to improve the search convenience is to show consumers a small set of frequently used searches conducted by peer consumers on the platform as a prime cue. We refer to this feature as the popular ranking search aid (PRSA). Collaborating with Meituan, a leading services mobile app in China, we implement a large-scale field experiment to explore how PRSA affects consumer search activities and purchases. Our analyses generate three key findings. First, PRSA leads to an increase of 18.6% in page views and a 6.4% increase in purchases. Second, the change in shopping behavior emerges through a change in search behavior with more non-directed searches and fewer directed searches. Third, our mediation analysis supports that search behavior mediates the business outcomes. We offer theoretical and managerial implications

Cytoplasm affects grain weight and filled-grain ratio in indica rice

<p>Abstract</p> <p>Background</p> <p>Cytoplasmic effects on agronomic traits -involving cytoplasmic and nuclear genomes of either different species or different cultivars - are well documented in wheat but have seldom been demonstrated in rice (<it>Oryza sativa </it>L.). To detect cytoplasmic effects, we introgressed the nuclear genomes of three <it>indica </it>cultivars - Guichao 2, Jiangchengkugu, and Dianrui 449 - into the cytoplasms of six <it>indica </it>cultivars - Dijiaowujian, Shenglixian, Zhuzhan, Nantehao, Aizizhan, and Peta. These 18 nuclear substitution lines were evaluated during the winter season of 2005 in Sanya, Hainan, China, and during the summer season of 2006 in Kunming, Yunnan, China. The effects of 6 cytoplasm sources, 3 nucleus sources, 2 locations and their interactions were estimated for plant height, panicle length, panicle number per plant, spikelet number per panicle, grain weight, filled-grain ratio, and yield per plot.</p> <p>Results</p> <p>For five of the seven traits, analysis of variance showed that there were no significant cytoplasmic effects or interactions involving cytoplasmic effects. The effect of cytoplasm on 1000-grain weight was highly significant. Mean 1000-grain weight over the two locations in four of the six cytoplasms clustered close to the overall mean, whereas plants with Nantehao cytoplasm had a high, and those with Peta cytoplasm a low mean grain weight. There was a highly significant three-way interaction affecting filled-grain ratio. At Sanya, cytoplasms varied in very narrow ranges within nuclear backgrounds. Strong cytoplasmic effects were observed only at Kunming and in only two of the three nuclear backgrounds; in the Jianchenkugu nuclear background, there was no evidence of strong cytoplasmic effects at either location. In the Dianrui 449 and Guichao 2 nuclear background evaluated at Kunming, filled-grain ratios of the six cytoplasms showed striking rank shifts</p> <p>Conclusions</p> <p>We detected cytoplasmic variation for two agronomically important traits in <it>indica </it>rice. The cytoplasm source had a significant effect on grain weight across the two experimental locations. There was also a significant cytoplasmic effect on filled-grain ratio, but only in two of three nuclear background and at one of the two locations. The results extend our previous findings with <it>japonica </it>rice, suggesting that the selection of appropriate cytoplasmic germplasm is broadly important in rice breeding, and that cytoplasmic effects on some traits, such as filled-grain ratio, cannot be generalized; effects should be evaluated in the nuclear backgrounds of interest and at multiple locations.</p

How Urbanization Economies Impact TFP of R&amp;D Performers: Evidence from China

There have been extensive studies exploring the relationship between agglomeration economies and economic growth. However, far less attention is paid to the nonlinear relationship of urbanization economies–firm productivity nexus, especially in developing countries. This paper aims to explore how urbanization economies impact the total factor productivity (TFP) of research and development (R&amp;D) performers using a large sample of Chinese manufacturing firms. The generalized propensity score matching methodology is employed to not only address the selection-bias and endogenous issues, but also quantitatively investigate how firm TFP responds to urbanization economies at each urbanization level. Based on the full data sample, our results show that there exists an S-shaped relationship between urbanization economies and TFP of Chinese R&amp;D performers. Importantly, there is an optimal interval in which urbanization economies’ impact on firm TFP can be maximized. There is also a threshold value, only beyond which a further increase in urbanization economies improves firm TFP, and a saturation point, beyond which a further increase in urbanization economies does not increase and even decrease firm TFP. The relationship between urbanization economies and TFP of Chinese R&amp;D performers presents a consistent pattern for firms in high- and medium–low-technology industries, as well as in Eastern and North East China. However, for firms in Central and Western China, there is a much smaller and even no range of optimal interval of urbanization economies, respectively. Our research helps provide insights into policy makers to maximize urbanization economies’ positive impact on firm TFP

Improving bridge effect to overcome interspecific hybrid sterility by pyramiding hybrid sterile loci from Oryza glaberrima

Abstract In order to evaluate the genetic effect caused by hybrid sterile loci, NILs with O. glaberrima fragment at six hybrid sterile loci under O. sativa genetic background (single-locus-NILs) were developed; two lines harboring two hybrid sterile loci, one line harboring three hybrid sterile loci were further developed. A total of nine NILs were used to test cross with O. sativa recurrent parent, and O. glaberrima accessions respectively. The results showed that the sterility of pollen grains in F1 hybrids deepened with the increase of the number of hybrid sterile loci, when the nine lines test crossed with O. sativa recurrent parent. The F1 hybrids were almost completely sterile when three hybrid sterile loci were heterozygeous. On the other hand, the single-locus-NILs had limited bridge effect on improving pollen grain fertility of interspecific hybrids. Compared single-locus-NILs, the multiple-loci-NILs showed increasing effect on pollen fertility when test crossing with O. glaberrima accessions. Further backcrossing can improve the fertility of pollen grain and spikelet of interspecific hybrids. The optimal solution to improve the fertility of interspecific hybrid can be utilization of pyramiding bridge parent plus backcrossing. This report has potential for understanding the nature of interspecific hybrid sterility, and overcoming the interspecific hybrid F1 pollen grain sterility between O. sativa and O. glaberrima