Missing at random, likelihood ignorability and model completeness

This paper provides further insight into the key concept of missing at random (MAR) in incomplete data analysis. Following the usual selection modelling approach we envisage two models with separable parameters: a model for the response of interest and a model for the missing data mechanism (MDM). If the response model is given by a complete density family, then frequentist inference from the likelihood function ignoring the MDM is valid if and only if the MDM is MAR. This necessary and sufficient condition also holds more generally for models for coarse data, such as censoring. Examples are given to show the necessity of the completeness of the underlying model for this equivalence to hold

Evidence Synthesis for Decision Making 4:Inconsistency in Networks of Evidence Based on Randomized Controlled Trials

Inconsistency can be thought of as a conflict between “direct” evidence on a comparison between treatments B and C and “indirect” evidence gained from AC and AB trials. Like heterogeneity, inconsistency is caused by effect modifiers and specifically by an imbalance in the distribution of effect modifiers in the direct and indirect evidence. Defining inconsistency as a property of loops of evidence, the relation between inconsistency and heterogeneity and the difficulties created by multiarm trials are described. We set out an approach to assessing consistency in 3-treatment triangular networks and in larger circuit structures, its extension to certain special structures in which independent tests for inconsistencies can be created, and describe methods suitable for more complex networks. Sample WinBUGS code is given in an appendix. Steps that can be taken to minimize the risk of drawing incorrect conclusions from indirect comparisons and network meta-analysis are the same steps that will minimize heterogeneity in pairwise meta-analysis. Empirical indicators that can provide reassurance and the question of how to respond to inconsistency are also discussed

Finding Trust Online: Tigergate to the Sichuan Earthquakes

On December 15, 2007, China Digital Times posted a story about last year’s “Tigergate incident.” Titled “The Truth is More Endangered than Tigers in China,” the story begins: The “South China Tiger” [华南虎］saga continues. Now known as “Tigergate” among Chinese netizens, this event will no doubt be one of the top media/internet stories of 2007. On December 2nd, NetEase (one of China’s leading news portals) published all 40 digital photos that farmer Zhou Zhenglong alleged he took of the tiger and also published six independent experts’ evaluations of the authenticity of these photos. These six independent third party evaluations include no less than American Chinese criminologist Henry Lee (李昌钰), the China Photographers Association (CPA)’s digital photo authentification center, and China’s top South China Tiger expert Hu Huijian (胡慧建). And all of their evaluations of the tiger photo reached the same conclusion: they’re fake

A Study on the Autonomous Learning Validity of Chinese EFL Students

In accordance with the autonomous learning theory, the present study mainly reports the validity of junior middle school students’ English autonomous learning and explores the strategies to improve students’ English level by the teaching experiment between two classes of Grade Eight in one of the key schools in Henan, China. The researcher selects 115 students as the research subjects who are from two classes of Grade Eight and the teaching experiment lasts for 18 weeks. In this research, the subjects are investigated with questionnaires and interviews. The research results show that students in class one who learn in autonomous ways have higher remarks than those in class two who learn in traditional ways. Students are quite interested in learning English and their ability of autonomous learning has been promoted with the teaching mode of autonomous learning. From the experiment results, it is shown that students’ learning ability can be improved with the training of the autonomous learning strategies. Based on the research results and the current learning situation, some suggestions on cultivating students’ ability of English learning is put forward in the end of this thesis

Swallowable Wireless Capsule Endoscopy: Progress and Technical Challenges

Wireless capsule endoscopy (WCE) offers a feasible noninvasive way to detect the whole gastrointestinal (GI) tract and revolutionizes the diagnosis technology. However, compared with wired endoscopies, the limited working time, the low frame rate, and the low image resolution limit the wider application. The progress of this new technology is reviewed in this paper, and the evolution tendencies are analyzed to be high image resolution, high frame rate, and long working time. Unfortunately, the power supply of capsule endoscope (CE) is the bottleneck. Wireless power transmission (WPT) is the promising solution to this problem, but is also the technical challenge. Active CE is another tendency and will be the next geneion of the WCE. Nevertheless, it will not come true shortly, unless the practical locomotion mechanism of the active CE in GI tract is achieved. The locomotion mechanism is the other technical challenge, besides the challenge of WPT. The progress about the WPT and the active capsule technology is reviewed

The Production-oriented Approach to Teaching English Writing in Chinese Junior High Schools

With the acceleration of globalization, English communicative competence has become a necessary ability in modern society. The teaching of English writing in junior high schools not only improves students’ comprehensive language ability, but also lays a favorable foundation for their future English learning. Writing classes should highlight the importance of writing. But in fact, students’ actual output is neglected. The writing classes exist in name only. Based on the above questions, this research attempts to apply the Production-Oriented Approach (POA) in junior high school English writing teaching which is proposed by Chinese scholar Wen Qiufang. This research aims to find the effectiveness of POA in English writing teaching of Chinese junior high schools. We adopt the experimental research approaches, using classroom observation, interviews and tests to collect research data. Taking a class of 50 students in Grade 8 of junior high school as the research subjects, the researcher carries out the production-oriented English teaching experiment for one semester. It has been found: (1) Compared with traditional English instructions, POA can improve the English writing quality and comprehensive language using ability of junior high school students. (2) Both teachers and students believe that POA can stimulate students’ positive emotional experience, and students have more opportunities to use language in class. Through “enabling”, the quality of students’ language output has been significantly improved

SI-FID: Only One Objective Indicator for Evaluating Stitched Images

Image quality evaluation accurately is vital in developing image stitching algorithms as it directly reflects the algorithms progress. However, commonly used objective indicators always produce inconsistent and even conflicting results with subjective indicators. To enhance the consistency between objective and subjective evaluations, this paper introduces a novel indicator the Frechet Distance for Stitched Images (SI-FID). To be specific, our training network employs the contrastive learning architecture overall. We employ data augmentation approaches that serve as noise to distort images in the training set. Both the initial and distorted training sets are then input into the pre-training model for fine-tuning. We then evaluate the altered FID after introducing interference to the test set and examine if the noise can improve the consistency between objective and subjective evaluation results. The rank correlation coefficient is utilized to measure the consistency. SI-FID is an altered FID that generates the highest rank correlation coefficient under the effect of a certain noise. The experimental results demonstrate that the rank correlation coefficient obtained by SI-FID is at least 25% higher than other objective indicators, which means achieving evaluation results closer to human subjective evaluation.Comment: 17 pages, 9 figure

Periodic boundary value problems for impulsive neutral differential equations with multi-deviation arguments

We develop the impulsive inequality and the classical lower and upper solutions, and establish the comparison principles. By using these results and the monotone iterative technique, we obtain the existence of solutions of periodic boundary value problems for a class of impulsive neutral differential equations with multi-deviation arguments. An example is given to demonstrate our main results. Mathematical subject classification: Primary: 34A37; Secondary: 34k10

COMPUTATIONAL STUDY OF LIQUID-SOLID INTERFACE

The solid interface is of fundamental importance to numerous scientific and technological fields, such as heterogeneous catalysis, water splitting, electrochemistry, corrosion, drug delivery, tribology, and wetting. However, there is still limited knowledge of the structures and properties of the first adsorbed monolayer at distinct solid interfaces. We perform theoretical calculations to study the interactions between the solid surfaces and the first adsorbed monolayer at the interface, to understand from the electronic/atomic levels how the properties of solid surface influence the adsorption of the first monolayer at the solid interfaces. In Chapter 3, we developed the force field parameter for the thiolate/defective Au(111) interface. A molecular-level understanding of the interplay between self-assembled monolayers (SAMs) of thiolates and gold surface is of great importance to a wide range of applications in surface science and nanotechnology. Despite theoretical research progress of the past decade, an atomistic model, capable of describing key features of SAMs at reconstructed gold surfaces, is still missing. We carried out the periodic ab initio density functional theory (DFT) calculations to develop a new atomistic force field model for alkanethiolate SAMs on a reconstructed Au(111) surface. Based on the newly-developed force field parameters, the molecular dynamics (MD) simulations showed that the geometrical features of the investigated Au−S interface models and structural properties of the C10S SAMs are in good agreement with the ab initio MD studies. In Chapter 4, we investigate the wettability transition of the first adsorbed water layer (FAWL) on metal surfaces under a compressive lattice strain. A molecular-level description of a near-surface water structure and a handy manipulation of its properties are relevant to a broad range of scientific and technological phenomena. Through a series of MD simulations, we report the observation and characterization of a low-mobility FAWL and its tunable wetting transition at three metal surface models. The results reveal that (i) there is a formation of the FAWL, resulting from competitive water−water hydrogen bonding and water−solid interactions, which in turn dictates the wettability at water−metal interfaces, (ii) applying compressive lattice strain to metal substrates can induce interfacial wettability transition, and (iii) by adjusting the lattice strains, the bimetallic junction can host a switchable wettability transition. In Chapter 5, we study the structures and dynamics of the FAWL at distinct titanium dioxide (TiO2) surfaces. The behavior of the FAWL at TiO2 surfaces is critical to the fundamental understanding of TiO2-based applications. Using classical MD simulations, we study the properties of FAWL at four TiO2 surfaces, including the density profile, the angular orientation distribution, the HB structural and dynamic properties, and the vibrational spectra of water molecules in the FAWL. The calculation results demonstrate that the water molecules show distinct adsorption structures and HB properties at the studied TiO2 surfaces, leading to completely different vibrational signatures for the OH groups. In Chapter 6, we explore the role of interfacial potassium on the surface-enhanced Raman spectroscopy for single-crystal TiO2 nanowhisker by combining experiments and theoretical calculations. For TiO2-based surface-enhanced Raman spectroscopy (SERS) substrates, maintaining a good crystallinity is critical to achieving excellent Raman scattering. we report the successful synthesis of TiO2 nanowhiskers with excellent SERS properties. The enhancement factor, an index of SERS performance, is 4.96×106 for methylene blue molecule detecting, with a detection sensitivity around 10−7 mol·L−1. The DFT calculations reveal that interfacial potassium can form a monolayer structure on the TiO2 surface, resulting in a negatively charged TiO2 nanowhisker surface. Such structures would promote the adsorption of methylene blue molecules and thereby significantly improves SERS performance via the electrostatic adsorption effect. In Chapter 7, we investigate the friction of ionic liquid (IL)–glycol ether mixtures by combining AFM experiments and nonequilibrium MD (NEMD) simulations. We have measured the negative “friction–load dependence” of IL/oil mixtures at Ti interfaces. Such a negative phenomenon was also confirmed by our NEMD simulations, in which the friction force declines as the normal load increases. NEMD simulations revealed a structural reorientation of the studied IL as the normal load increases, i.e., the cation alkyl chains of ILs change the orientation to preferentially stay parallel to the tip scanning path, similar to the “blooming lotus leaf.” This reoriented IL structures produce a new sliding interface and reduce the friction force