A Simple,Flexible Failure Model

A new failure model is introduced in the form of a four-parameter nonlinear differential equation, with failure probability as the dependent variable and failure time as the independent variable. The first parameter characterizes the location, the second the scale, and the other two the shape of the model. The type of the accompanying hazard function is immediately read off the shape parameters. The new model approximates the classical failure models with rather high precision, but also models cases where the failure density is skewed to the left. It can be used to analyze survival data objectively, based on the shape of the failure distribution. The computation of quantiles and moments is easy and fast. Nonlinear regression methods are used to estimate parameter values.     

Phylogenetic diversity is a better predictor of wetland community resistance to Alternanthera philoxeroides invasion than species richness

• Highly biodiversity communities have been shown to better resist plant invasions through complementarity effects. Species richness (SR) is a widely used biodiversity metric but lacks explanatory power when there are only a few species. Communities with low SR can have a wide variety of phylogenetic diversities (PD), which might allow for a better prediction of invasibility.
• We assessed the effect of diversity reduction of a wetland community assemblage typical of the Beijing area on biotic resistance to invasion of the exotic weed Alternanthera philoxeroides and compared the reduction in SR and PD in predicting community invasibility.
• The eight studied resident species performed similarly when grown alone and when grown in eight‐species communities together with the invasive A. philoxeroides. Variation partitioning showed that PD contributed more to variation in both A. philoxeroides traits and community indicators than SR. All A. philoxeroides traits and community indicators, except for evenness index, showed a linear relationship with PD. However, only stem length of A. philoxeroides differed between the one‐ and two‐species treatments, and the diversity index of the communities differed between the one‐ and two‐species treatments and between the one‐ and four‐species treatments.
• Our results showed that in natural or semi‐natural wetlands with relatively low SR, PD may be a better predictor of invasibility than SR. When designing management strategies for mitigating A. philoxeroides invasion, deliberately raising PD is expected to be more efficient than simply increasing species number.

     

Modification of donor lymphocyte infusion: how to improve the outcome?

<正>Even after allogeneic hematopoietic stem cell transplantation(HSCT), which has been acknowledged as a curative procedure, relapse of leukemia remains the leading cause of death following transplantation and is a disappointment to transplant physicians. Leukemic relapse occurs due to leukemia cell escape from immune-mediated killing (immune escape) by pre-transplantation conditioning and post-transplantation immune control. Immune exhaustion of donor T     

Statures in Han populations of China

<正>Dear Editor,Shortly after initiating the"Physical Anthropological Research on Han Chinese"research project,we applied uniform sampling methods as well as methods and instruments of measurement to obtain a complete set of measurements of physical anthropological indicators among Han populations across China.Among these measurements,body stature was a key indicator.Currently,there should be reliable