Evaluating FIML and multiple imputation in joint ordinal-continuous measurements models with missing data.

Missing data is a common occurrence in confirmatory factor analysis (CFA). Much work had evaluated the performance of different techniques when all observed variables were either continuous or ordinal. However, few have investigated these techniques when observed variables are a mix of continuous and ordinal variables. This study investigated the performance of four approaches to handling missing data in these models: a joint ordinal-continuous full information maximum likelihood (FIML) approach and three multiple imputation approaches (fully conditional specification, fully conditional specification with latent variable formulation, and expectation-maximization with bootstrapping) combined with the weighted least squares with mean and variance adjustment (WLSMV) estimator. In a Monte-Carlo simulation, the FIML approach produced unbiased estimations of factor loadings and standard errors in almost all conditions. Fully conditional specification combined with WLSMV was second best, producing accurate estimates when the sample size was large. However, FIML encountered slight non-convergence issues when certain ordinal categories have extremely low frequencies, which is typical of skewed data. If the sample is large, fully conditional specification combined with weighted least squares is recommended when the FIML approach is not feasible (e.g., non-convergence, impractical computation durations, and variables that predict missingness are not of interest to the analysis).

The data not collected on community forestry.

Conservation and development practitioners increasingly promote community forestry as a way to conserve ecosystem services, consolidate resource rights, and reduce poverty. However, outcomes of community forestry have been mixed; many initiatives failed to achieve intended objectives. There is a rich literature on institutional arrangements of community forestry, but there has been little effort to examine the role of socioeconomic, market, and biophysical factors in shaping both land-cover change dynamics and individual and collective livelihood outcomes. We systematically reviewed the peer-reviewed literature on community forestry to examine and quantify existing knowledge gaps in the community-forestry literature relative to these factors. In examining 697 cases of community forest management (CFM), extracted from 267 peer-reviewed publications, we found 3 key trends that limit understanding of community forestry. First, we found substantial data gaps linking population dynamics, market forces, and biophysical characteristics to both environmental and livelihood outcomes. Second, most studies focused on environmental outcomes, and the majority of studies that assessed socioeconomic outcomes relied on qualitative data, making comparisons across cases difficult. Finally, there was a heavy bias toward studies on South Asian forests, indicating that the literature on community forestry may not be representative of decentralization policies and CFM globally.

Antioxidant enzymes, free-radical damage, and response to paraquat in liver and kidney of long-living growth hormone receptor/binding protein gene-disrupted mice.

Numerous studies have shown that the lifespan can be extended by caloric restriction or by altering the growth hormone (GH)-insulin-like growth factor 1 signaling pathway. Both of these manipulations produce physiological alterations, such as increased insulin sensitivity, and reduced glucose levels and body size. However, it is difficult to evaluate whether these are merely correlates of delayed aging or whether they have a direct causal effect on lifespan. One parameter that has been demonstrated to have causal, positive effects on longevity in invertebrates is improved antioxidant defenses. We measured activities of antioxidant enzymes Cu/Zn superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) and quantified free-radical damage by lipid peroxidation (LP) and protein oxidation (PO) measurements in liver and kidney tissues, and evaluated the response to paraquat-induced oxygen toxicity in the long-living GH receptor/binding protein gene knockout (GHR-KO) mouse. We found that in the kidney, SOD was lower and GPx was higher in GHR-KO mice, and LP was higher in female GHR-KO mice only. In the liver, female GHR-KO mice had lower GPx, while male GHR-KO mice had lower CAT and higher LP. GHR-KO males were also more susceptible to paraquat toxicity compared to females or normal males. We conclude that in long-living GHR-KO mice, GH-resistance does not confer longevity by improved free-radical scavenging in the liver and kidney, suggesting that greater free-radical defenses in other tissues, or altered glucose metabolism may have a more central role in extending the lifespan of these animals.