Lifted Multiplicity Codes and the Disjoint Repair Group Property

Lifted Reed Solomon Codes (Guo, Kopparty, Sudan 2013) were introduced in the context of locally correctable and testable codes. They are multivariate polynomials whose restriction to any line is a codeword of a Reed-Solomon code. We consider a generalization of their construction, which we call lifted multiplicity codes. These are multivariate polynomial codes whose restriction to any line is a codeword of a multiplicity code (Kopparty, Saraf, Yekhanin 2014). We show that lifted multiplicity codes have a better trade-off between redundancy and a notion of locality called the t-disjoint-repair-group property than previously known constructions. More precisely, we show that, for t <=sqrt{N}, lifted multiplicity codes with length N and redundancy O(t^{0.585} sqrt{N}) have the property that any symbol of a codeword can be reconstructed in t different ways, each using a disjoint subset of the other coordinates. This gives the best known trade-off for this problem for any super-constant t < sqrt{N}. We also give an alternative analysis of lifted Reed Solomon codes using dual codes, which may be of independent interest

Are workers close to cities paid higher non-agricultural wages in rural China?

In the present study, we investigate whether workers close to cities are paid higher non-agricultural wages than workers in outlying rural areas. We find that workers close to urban areas not only benefit from more opportunities to engage in non-agricultural activities, but also from better paid jobs. In addition, distance exhibits a strongly nonlinear impact. Distance always has a negative impact on wages but the effect is more detrimental, the closer the village is to the urban center. We also find evidence of urban hierarchy effects: workers living close to bigger cities are paid higher wages. Finally, we provide evidence on the transmission channels at work.Remoteness, regional labor market, China Codes, wages

The response of Liriope, Hosta, and Hedera to sunlight and fertilization

The purpose of this investigation was to study the response of three different species of ground covers, Liriope, Hosta, and Hedera to various degrees of shade and levels of nitrogen and potassium. The plants were grown in pots under three light conditions: full sunlight, half of full sunlight, and a quarter of full sunlight. Two levels of nitrogen and po-tassium, high and low, were applied at the beginning of this experiment. Data for this study included height, fresh and dry weights, number of leaves or shoots, chlorophyll and starch content. Height and number of leaves of these three ground covers were significantly affected by light and nitrogen treatment. In most cases, the reduction of light and a high nitrogen level produced better growth and better ap-pearing plants than were obtained under full sunlight and low nitrogen fertilization. Differences due to potassium levels were usually non-significant

Birth Weight as a Risk Factor for Breast Cancer: a Meta-Analysis of 18 Epidemiologic Studies

Background: Birth weight has been identified as a birth-related factor associated with the risk of breast cancer. However, the evidence is inconsistent. Methods: To investigate the association between birth weight and breast cancer, we conducted a meta-analysis of published studies between 1996 and 2008. Eighteen studies encompassing 16,424 breast cancer cases were included in the meta-analysis. Data were combined using a fixed-effect or random-effect model depending on the heterogeneity across studies. Results: Women with their own birth weight \u3e4000 g or 8.5 lb had a higher risk for developing breast cancer than those with birth weight(OR¼1.20, 95% CI 1.08, 1.34). Findings were also consistent with a dose-response pattern effect. The summary effect estimate for breast cancer risk per 1 kg increase in birth weight was statistically significant (random effects OR¼1.07, 95% CI 1.02, 1.12). Conclusions: Although these results provided no evidence indicating whether birth weight is more strongly related to early-onset than to later-onset breast cancer, our findings suggest an association between birth weight and breast cancer. The underlying biological mechanism relating to this phenomenon needs additional study