Chinese is written without using spaces or other word delimiters. Although a text may be thought of as a corresponding sequence of words, there is considerable ambiguity in the placement of boundaries. Interpreting a text as a sequence of words is beneficial for some information retrieval and storage tasks: for example, full-text search, word-based compression, and keyphrase extraction. We describe a scheme that infers appropriate positions for word boundaries using an adaptive language model that is standard in text compression. It is trained on a corpus of presegmented text, and when applied to new text, interpolates word boundaries so as to maximize the compression obtained. This simple and general method performs well with respect to specialized schemes for Chinese language segmentation.

Background Myopia is a good model for understanding the interaction between genetics and environmental stimuli. Here we dissect the biological processes affecting myopia progression. Methods Human Genetic Analyses: (1) gene set analysis (GSA) of new genome wide association study (GWAS) data for 593 individuals with high myopia (refraction ≤ -6 diopters [D]); (2) over-representation analysis (ORA) of 196 genes with de novo mutations, identified by whole genome sequencing of 45 high-myopia trio families, and (3) ORA of 284 previously reported myopia risk genes. Contributions of the enriched signaling pathways in mediating the genetic and environmental interactions during myopia development were investigated in vivo and in vitro . Results All three genetic analyses showed significant enrichment of four KEGG signaling pathways, including amphetamine addiction, extracellular matrix (ECM) receptor interaction, neuroactive ligand-receptor interaction, and regulation of actin cytoskeleton pathways. In individuals with extremely high myopia (refraction ≤ -10 D), the GSA of GWAS data revealed significant enrichment of the HIF-1α signaling pathway. Using human scleral fibroblasts, silencing the key nodal genes within protein-protein interaction networks for the enriched pathways antagonized the hypoxia-induced increase in myofibroblast transdifferentiation. In mice, scleral HIF-1α downregulation led to hyperopia, whereas upregulation resulted in myopia. In human subjects, near work, a risk factor for myopia, significantly decreased choroidal blood perfusion, which might cause scleral hypoxia. Interpretation Our study implicated the HIF-1α signaling pathway in promoting human myopia through mediating interactions between genetic and environmental factors. Funding National Natural Science Foundation of China grants; Natural Science Foundation of Zhejiang Province.

Myopia is a serious sight-compromising condition in which decreases in scleral biomechanical strength are associated with protease up-regulation resulting in thinning of its collagenous framework and changes in the extracellular matrix composition. Matrix metallopeptidase (MMP)-2 is one of the known proteases mediating these alterations. To determine whether MMP-2 up-regulation precedes myopia development, the direct effects of gain and loss in Mmp2 gene function were evaluated on refractive development and form deprivation myopia in mice. Four weeks after injecting an adeno-associated virus serotype 8 packaged Mmp2 overexpression vector (AAV8-Mmp2), scleral MMP-2 up-regulation was accompanied by significant myopia in a normal visual environment. In contrast, AAV8 packaging with shRNA targeting Mmp2 inhibited rises in MMP-2 expression induced by form deprivation by 54% and reduced myopia development by 23% compared with eyes injected with an irrelevant scrambled sequence. Because opposing changes in MMP-2 protein expression levels had corresponding effects on myopia progression, up-regulation of this protease contributes to inducing this condition. This notion of a cause-and-effect relationship between MMP-2 up-regulation and myopia development is supported by showing that form-deprived myopia development was attenuated by 27% in fibroblast-specific Mmp2 deletion (S100a4Mmp2) mice relative to Cre-negative littermates (Mmp2). Therefore, MMP-2 is a potential drug target for inhibiting myopia progression.