Nonparametric estimation of natural direct and indirect effects based on inverse probability weighting

Using a sequential conditional independence assumption, this paper discusses fully nonparametric estimation of natural direct and indirect causal effects in causal mediation analysis based on inverse probability weighting. We propose estimators of the average indirect effect of a binary treatment, which operates through intermediate variables (or mediators) on the causal path between the treatment and the outcome, as well as the unmediated direct effect. In a first step, treatment propensity scores given the mediator and observed covariates or given covariates alone are estimated by nonparametric series logit estimation. In a second step, they are used to reweigh observations in order to estimate the effects of interest. We establish root-n consistency and asymptotic normality of this approach as well as a weighted version thereof. The latter allows evaluating effects on specific subgroups like the treated, for which we derive the asymptotic properties under estimated propensity scores. We also provide a simulation study and an application to an information intervention about male circumcisions

Experimental Study on Hydraulic Jumps with and Without Sediment

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

On the Steady Standing Surface Wave Pattern of Flows in a Narrow Rectangular Straight Chute

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Practical Automatic Tuning of Lag-lead Compensators for Feedback Control Systems

This paper proposes a scheme for auto-tuning a lag-lead compensator to satisfy frequency-domain specifications of a feedback control system. Most previous studies proposed algorithms for tuning either lag or lead compensators. A study presented a self-tuning lag-lead compensator whose proportional gain, however, needs to be set manually. In contrast to previous studies, a fully automated tuning process for a lag-lead compensator is devised in this paper. In the proposed scheme, the plant's frequency responses at specific frequencies are first estimated, and an iterative algorithm adapts all controller parameters. To facilitate the estimation of high loop gain at a low frequency, a notch filter is introduced to the control loop while estimating this high low-frequency loop gain. Without this mechanism, a real-time data acquisition system of a wide dynamic range would be required. In addition to fulfilling the requirements for the low-frequency loop gain and phase margin, another feature of the proposed scheme is the satisfaction of the required gain-crossover frequency. However, the proposed method supposes that the frequency-domain specifications can be met for a plant using a lag-lead compensator, which is the plant's requirement for the proposed method. Experimental results for controlling a voice-coil motor are reported in this paper, showing that the proposed auto-tuner can practically provide a lag-lead compensated system satisfying frequency-domain performance requirements

Intra-abdominal abscess caused by toothpick injury

SummaryWe present the case of a 42-year-old female who presented to our emergency department (ED) complaining of epigastric pain for four days. She had been seen in the outpatient department and ED previously for evaluation, but continued to experience epigastric pain with fever. Emergency panendoscopy was performed and a toothpick was discovered impacted in the duodenal bulb. The gastroenterologist was unable to remove the toothpick endoscopically. Computed tomography of the abdomen revealed a long and straight hyperdense foreign body, and intra-abdominal abscess formation. An emergency laparotomy was performed. The patient recovered gradually and was discharged 11 days later. She could not remember when she swallowed the wooden toothpick, but guessed that it was while out drinking. There is an old wives’ tale in Taiwan that putting a toothpick in the cup while drinking beer reduces the likelihood of abdominal distention from the carbonation of the beer

The Effect of M&A on Wage: Evidence from Financial Institution in Taiwan, ROC

Abstract: Our empirical results provide evidence that department merge of firms will increase the profit through the reduction of labor cost and support why workers in horizontal mergers may share in any increases in the production surplus rather than those on vertical mergers (Horn and Wolinsky; 1988). On the other hand, the expansion of department in the firm will lead to a negative scale effect. The production cost will increase due to the higher labor cost. However, it only has significant effect on M&A within the same industry. It implies that horizontal mergers will have more chance to expansion of department in the firm because the market share of products will increase

The Effect of M&A on Wage: Evidence from Financial Institution in Taiwan ROC

Abstract: Our empirical results provide an evidence, department merge of firms will increase the profit through the reduction of labor cost, and support why workers in horizontal mergers may share in any increases in the production surplus rather than those on vertical merger

On character table of Clifford groups

Based on a presentation of $\mathcal{C}_n$ and the help of [GAP], we construct the character table of the Clifford group $\mathcal{C}_n$ for $n=1,2,3$. As an application, we can efficiently decompose the (higher power of) tensor product of the matrix representation in those cases. Our results recover some known results in [HWW, WF] and reveal some new phenomena. We prove that the trivial character is the only linear character for $\mathcal{C}_n$ and hence $\mathcal{C}_n$ equals to its commutator subgroup when $n\geq 3$. A few conjectures about $\mathcal{C}_n$ for general $n$ are proposed.Comment: 13 pages; comments and suggestions are welcom