Leveraging Auxiliary Information on Marginal Distributions in Nonignorable Models for Item and Unit Nonresponse

Often, government agencies and survey organizations know the population counts or percentages for some of the variables in a survey. These may be available from auxiliary sources, for example, administrative databases or other high quality surveys. We present and illustrate a model-based framework for leveraging such auxiliary marginal information when handling unit and item nonresponse. We show how one can use the margins to specify different missingness mechanisms for each type of nonresponse. We use the framework to impute missing values in voter turnout in a subset of data from the U.S. Current Population Survey (CPS). In doing so, we examine the sensitivity of results to different assumptions about the unit and item nonresponse.

Surgical Adjuncts to Rhinoplasty: An Algorithmic Approach

BACKGROUND

Nasal aesthetics can be significantly affected by the interdependence of the surrounding bone and soft tissues of the face. These include the maxilla, septum, frontal bone, mandible, and the soft tissues and cartilage surrounding the nose. Therefore, it is pertinent to analyze and address these critical relationships of the nose in order to achieve a successful rhinoplasty. This work seeks to describe the battery of adjunct procedures available to supplement a rhinoplasty. Furthermore, each preoperative finding or indication for the adjunct is described in an algorithmic fashion.

METHODS

A literature search using PubMed, Google Scholar, and a university library database was performed to locate papers describing adjunctive procedures to rhinoplasty. Indications and preoperative analysis were extracted from each paper. If the indication or finding was unclear, supplementary literature describing rhinoplasty and adjunctive analysis were sought in order to supplement our findings.

RESULTS

Sixteen papers in total described adjunctive procedures for rhinoplasty. Each work highlighted a procedure or set of procedures on a surrounding facial feature including the forehead, brow, cheeks, lips, and chin, and neck. In total, 13 adjunct procedures for rhinoplasty are described with their respective indications. Additional literature and techniques were researched to clarify indicated procedures.

CONCLUSION

The ability to correctly understand the critical relationships of the nose can help the surgeon correctly recognize the indication for a rhinoplasty adjunct procedure, leading to better aesthetic balance and surgical outcomes.

LEVEL OF EVIDENCE II

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Facile Semisynthesis of Ubiquitylated Peptides with the Ligation Auxiliary 2-Aminooxyethanethiol

The posttranslational modification of cellular proteins by ubiquitin (Ub), called ubiquitylation, is indispensable for the normal growth and development of eukaryotic organisms. In order to conduct studies that elucidate the precise mechanistic roles for Ub, access to site-specifically and homogenously ubiquitylated proteins and peptides is critical. However, the low abundance, heterogeneity, and dynamic nature of protein ubiquitylation are significant limitations toward such studies. Here we provide a facile expressed protein ligation method that does not require specialized apparatus and permits the rapid semisynthesis of ubiquitylated peptides by using the atom-efficient ligation auxiliary 2-aminooxyethanethiol.

Scope of practice and supervision of orthodontic therapists in the United Kingdom: Part 1: a national cross-sectional survey of orthodontists

OBJECTIVE

Since the introduction of orthodontic therapists (OTs), there has been little research on the scope of practice and the level of supervision they receive. This study investigates how OTs are being utilised and supervised, and how this compares with current recommendations.

METHODS AND PARTICIPANTS

A postal cross-sectional survey was mailed to all UK General Dental Council (GDC) registered specialist orthodontists.

RESULTS

A 59.7% response rate (747) was achieved. 52% of the respondents reported they worked with/employed an OT. The majority of orthodontists worked with an OT in primary care (67%) seeing predominantly NHS (56%) patients and performed a wide range of duties. Orthodontists reported a perceived increase in clinical output (74%) and time available for treatment planning (61%). The majority (85%) of orthodontists indicated they provide a written prescription for the OT. Forty-two per cent reported the prescription did not contain the required information as stipulated by the GDC.

CONCLUSIONS

OTs are valued members of the orthodontic team, improving productivity and allowing orthodontists more time for treatment planning. The majority of orthodontists appeared to be working to the BOS and GDC recommendations, with greater awareness needed regarding the provision of a written treatment prescription.

The genomic content and context of auxiliary metabolic genes in marine cyanomyoviruses

Viruses of marine cyanobacteria frequently contain auxiliary metabolic genes (AMGs) that augment host metabolism during infection, but little is known about their adaptive significance. We analyzed the distribution and genomic context of 33 AMGs across 60 cyanomyovirus genomes. Similarity in AMG content among cyanomyoviruses was only weakly correlated with phylogenetic relatedness; however, AMG content was generally conserved within the same operational taxonomic unit (OTU). A virus' AMG repertoire was also correlated with its isolation host and environment (coastal versus open ocean). A new analytical method based on shared co-linear blocks revealed that variation in the genomic location of an AMG was negatively correlated with its frequency across the genomes. We propose that rare AMGs are more frequently gained or lost as a result of fluctuating selection pressures, whereas common AMGs are associated with stable selection pressures. Finally, we describe a unique cyanomyovirus (S-CAM7) that lacks many AMGs including the photosynthesis gene psbA.

Clinical application of a self-made capsule endoscope pusher

AIM: To observe the clinical effects of a self-made capsule endoscope pusher, in order to solve the problem of gastric retention of capsule endoscope.

METHODS: Forty selective patients with gastric retention of capsule endoscope were divided into two groups (n = 20 for each): an observation group and a control group. In the observation group, the pusher was mounted to the duodenoscope front to push the capsule endoscope into the duodenum, and the capsule endoscopy was then released into the duodenum using biopsy forceps. In the control group, a snare trap was used to push the capsule endoscope into the duodenum for release.

RESULTS: In the observation group, all endoscopes were pushed through the pylorus into the duodenum, with a success rate of 100%. The success rate in the control group was 40%. In the observation group, the success rate and the compliance of patients were significantly higher than those in the control group (P < 0.01). The total operative time and the running time were not statistically significant between the two groups (P > 0.05).

CONCLUSION: The capsule endoscope pusher is simple and practical, with a higher success rate, less adverse reactions, and better compliance. It solves the problem of gastric retention of capsule endoscope; however, it has disadvantage of invasiveness, pain, and increased costs.

Semiparametric estimation in generalized linear mixed models with auxiliary covariates: a pairwise likelihood approach

Auxiliary covariates are often encountered in biomedical research settings where the primary exposure variable is measured only for a subgroup of study subjects. This article is concerned with generalized linear mixed models in the presence of auxiliary covariate information for clustered data. We propose a novel semiparametric estimation method based on a pairwise likelihood function and develop an estimating equation-based inference procedure by treating both the error structure and random effects as nuisance parameters. This method is robust against misspecification of either error structure or random-effects distribution and allows for dependence between random effects and covariates. We show that the resulting estimators are consistent and asymptotically normal. Extensive simulation studies evaluate the finite sample performance of the proposed estimators and demonstrate their advantage over the validation set based method and the existing method. We illustrate the method with two real data examples.

Test the reliability of doubly robust estimation with missing response data

In statistical inference, one has to make sure that the underlying regression model is correctly specified otherwise the resulting estimation may be biased. Model checking is an important method to detect any departure of the regression model from the true one. Missing data are a ubiquitous problem in social and medical studies. If the underlying regression model is correctly specified, recent researches show great popularity of the doubly robust (DR) estimates method for handling missing data because of its robustness to the misspecification of either the missing data model or the conditional mean model, that is, the model for the conditional expectation of true regression model conditioning on the observed quantities. However, little work has been devoted to the goodness of fit test for DR estimates method. In this article, we propose a testing method to assess the reliability of the estimator derived from the DR estimating equation with possibly missing response and always observed auxiliary variables. Numerical studies demonstrate that the proposed test can control type I errors well. Furthermore the proposed method can detect departures from model assumptions in the marginal mean model of interest powerfully. A real dementia data set is used to illustrate the method for the diagnosis of model misspecification in the problem of missing response with an always observed auxiliary variable for cross-sectional data.