Marginal Time-Dependent Causal Effects in Mediation Analysis With Survival Data.

The main aim of mediation analysis is to study the direct and indirect effects of an exposure on an outcome. To date, the literature on mediation analysis with multiple mediators has mainly focused on continuous and dichotomous outcomes. However, the development of methods for multiple mediation analysis of survival outcomes is still limited. Here we extend to survival outcomes a method for multiple mediation analysis based on the computation of appropriate weights. The approach considered has the advantages of not requiring specific models for mediators, allowing nonindependent mediators of any nature, and not relying on the assumption of rare outcomes. Simulation studies show good performance of the proposed estimator in terms of bias and coverage probability. The method is further applied to an example from a published study on prostate cancer mortality aimed at understanding the extent to which the effect of DNA methyltransferase 3b (DNMT3b) genotype on mortality was explained by DNA methylation and tumor aggressiveness. This approach can be used to quantify the marginal time-dependent direct and indirect effects carried by multiple indirect pathways, and software code is provided to facilitate its application.

GNSS Code Multipath Mitigation by Cascading Measurement Monitoring Techniques.

Various measurement monitoring techniques are investigated to mitigate the effect of global navigation satellite systems (GNSS) code multipath through error correction, stochastic weighting of measurements and detection and exclusion (or de-weighting) of affected measurements. Following a comprehensive review of each approach, the paper focuses on detection/exclusion and detection/de-weighting techniques where several single and dual-frequency monitoring metrics are employed in a combination with time-averaging and the M of N detection strategy. A new Geometry-Free (GF) detection metric is proposed given its capability to be combined with a preceding Code-Minus-Carrier (CMC)-based error correction to reduce the number of excluded or de-weighted measurements and thus preserve the measurement geometry. Three geometry-based algorithms, namely measurement subset testing, consecutive exclusion and iterative change of measurement weights are investigated to address multipath scenarios with multiple simultaneously affected measurements. Experimental results are provided using GPS L1, L2C and L5 data collected in multipath environments for static and kinematic scenarios. For GPS L1, the proposed combined method shows more than 38% improvement over a conventional Carrier-to-Noise-density ratio (C/N0)-based Least-Squares (LS) solution in all but deep urban canyons. Lower performance was observed for L2C and L5 frequencies with a limited number of satellites in view.

Lobar size reduction in lung transplantation: A propensity score study.

OBJECTIVE: For small-sized recipients of lung transplantation, the time span for organ reception from standard donors is generally longer than for normal-sized patients. Despite its underuse, lobar reduction may be a concrete option for these patients. This study aims to assess early and long-term outcomes associated with lobar reduction in lung transplantation. METHODS: A retrospective study was performed on 608 consecutive lung transplantations at 2 centers between January 2005 and August 2019 (559 standard lung transplantations [standard transplantation] and 49 with lobar reduction [lung transplantation group]). A propensity-score weighting approach was used to account for potential confounding related to patients' nonrandom allocation to the 2 intervention groups. The effects of the intervention on postoperative outcomes were assessed with a weighted regression approach. RESULTS: The propensity score was estimated on 571 patients (522 in standard transplantation group and 49 in lung transplantation group). In terms of early outcomes, the lung transplantation group showed a higher percentage of severe primary graft dysfunction at 0 hours and reported longer intensive care unit stay than the standard transplantation group. No other differences in terms of morbidity, mortality, mechanical ventilation time, hospital stay, and anastomotic complications were observed. Although the lung transplantation group showed worse long-term pulmonary function, the 2 populations had comparable survival outcomes. CONCLUSIONS: The use of lobar reduction showed early and long-term results comparable to those after standard lung transplantation. Although a higher rate of early severe primary graft dysfunction and slightly reduced respiratory function were detected in the lobar group, these did not affect patients' morbidity and survival.

Evaluation of mining capacity of mines using the combination weighting approach: A case study in Shenmu Mining Area in Shaanxi Province, China.

Aiming at the low mining rate in mines, Xingelao, Dabianyao, and Dongliang Coal Mines in Shenmu Mining Area, Shaanxi Province, China were taken as research objects. Based on this, this study constructed an evaluation index system for the mining capacity of the mines from the perspectives of geological factors, mechanical equipment, humans, and mining design. Moreover, the factors influencing the mining capacity of the mines were evaluated using a combination weighting approach based on an improved analytic hierarchy process and an entropy weight method. A standard cloud was generated based on the mapping standards of each index and a comprehensive cloud was obtained according to comprehensive weight and a backward cloud algorithm. Finally, by combining the comprehensive cloud with local and overall scores of the mines, the mining capacities of the mines were evaluated. The research results demonstrate that the key factor restricting the mining capacity of the mines is the geological environment and five major third-grade indexes affecting mining capacity are igneous rock intrusion, collapse column, scouring zone of the ancient river bed, mechanization level and coal pillar width. In addition, the corresponding suggestions and measures were put forward according to the main factors influencing the mining rate of the mines. In accordance with the weights and scores of each index, the overall scores of the mines were calculated. Dongliang, Dabianyao, and Xingelao Coal Mines were ranked in order based on scores. The research results provide a theoretical basis for improving the mining capacity of the mines under similar geological conditions.