Fast and one-step folding of closely and distantly related homologous proteins of a four-helix bundle family

Bovine acyl-coenzyme A binding protein is a four-helix bundle protein belonging to a group of homologous eukaryote proteins that binds medium and long-chain acyl-coenzyme A esters with a very high affinity. The three-dimensional structure of both the free and the ligated protein together with the folding kinetics have been described in detail for the bovine protein and with four new sequences reported here, a total of 16 closely related sequences ranging from yeasts and plants to human are known. The kinetics of folding and unfolding in different concentrations of guanidine hydrochloride together with equilibrium unfolding have been measured for bovine, rat and yeast acyl-coenzyme A binding protein. The bovine and rat sequences are closely related whereas the yeast is more distantly related to these. In addition to the three natural variants, kinetics of a bovine mutant protein, Tyr31 --> Asn, have been studied. Both the folding and unfolding rates in water of the yeast protein are 15 times faster than those of bovine. The folding rates in water of the two mammalian forms, rat and bovine, are similar, though still significantly different. A faster unfolding rate both for rat and the bovine mutant protein results from a lower stability of the native states of these. These hydrophobic regions, mini cores, have been identified in the three-dimensional structure of the bovine protein and found to be formed primarily by residues that have been conserved throughout the entire eukaryote evolution from yeasts to both plants and mammals as seen in the sample of 16 sequences. The conserved residues are found to stabilize helix-helix interactions and serve specific functional purposes for ligand binding. The fast one-step folding mechanism of ACBP has been shown to be a feature that seems to be maintained throughout evolution despite numerous differences in sequence and even dramatic differences in folding kinetics and protein stability. The protein study raises the question to what extent does the conserved hydrophobic residues provide a scaffold for an efficient one-step folding mechanism.     

基于矩阵分解双线性池化的多模态融合虚假新闻检测

现有的大多数虚假新闻检测方法将视觉和文本特征串联拼接,导致模态信息冗余并且忽略了不同模态信息之间的相关性。为了解决上述问题,提出一种基于矩阵分解双线性池化的多模态融合虚假新闻检测算法。首先,该算法将多模态特征提取器捕捉的文本和视觉特征利用矩阵分解双线性池化方法进行有效融合,然后与虚假新闻检测器合作鉴别虚假新闻;此外,在训练阶段加入了事件分类器来预测事件标签并去除事件相关的依赖。在Twitter和微博两个多模态谣言数据集上进行了对比实验,证明了该算法的有效性。实验结果表明提出的模型能够有效地融合多模态数据,缩小模态间的异质性差异,从而提高虚假新闻检测的准确性。     

Potential applications of three-way multidimensional scaling and related techniques to integrate knowledge from multiple experts

Theknowledge transfer problem in artificial intelligence consists of finding effective ways to elicit information from a human expert and represent it in a form suitable for use by an expert system. One approach to formalizing and guiding this knowledge transfer process for certain types of expert systems is to use psychometric scaling methods to analyze data on how the human expert compares or groups solutions. For example, Butler and Corter [1] obtained judgments of thesubstitutability of solutions from an expert, then analyzed the resulting data via techniques for fitting trees and extended trees [2]. The expert's interpretation of certain aspects of the solutions were directly encoded as production rules, allowing rapid prototyping. In this paper we consider the problem of combining information from multiple experts. We propose the use of three-way or individual differences multidimensional scaling, tree-fitting, and unfolding models to analyze two types of data obtainable from the multiple experts: judgments of the substitutability of pairs of solutions, and judgments of the appropriateness of specific solutions to specific problems. An application is described in which substitutability data were obtained from three experts and analyzed using the SINDSCAL program [3] for three-way multidimensional scaling [4].     

Synthesis and material and electronic properties of conjugated polymers

Conjugated polymers such as polyacetylene are semiconductors, and can be chemically doped to give very high values of conductivity (up to 150 000 S cm^–1). The semiconducting properties are due to delocalization of the electron system formed along the polymer chain, and this general class of materials shows many desirable semiconductor properties for electrical and optical applications. There are considerable challenges to find synthetic routes to allow processing of the polymer to the forms required for applications, and many of the recent important advances in the field are due to improvements in this area.     

Protected completions of first-order general logic programs

Minker and Perlis [15] have made the important observation that in certain circumstances, it might be desirable to prevent the inference of A when A is in the finite failure set of a logic program P. In this paper, we investigate the model-theoretic aspects of their proposal and develop a Fitting-style [5] declarative semantics for protected completions of general logic programs (containing function symbols). This extends the Minker-Perlis proposal which applies to function-free pure logic programs. In addition, an operational semantics is proposed and it is proven to be sound for existentially quantified positive queries and negative ground queries to general, canonical protected logic programs. Completeness issues are investigated and completeness is proved for positive existential queries and negative ground queries for the following classes of programs: (1) function-free general protected logic programs (the Minker-Perlis operational semantics apply to function-free pure protected logic programs), (2) pure protected logic programs (with function symbols) and (3) protected general logic programs that do not contain any internal variables (though they may contain function symbols).     

Investigation of long term drift of an intraocular pressure sensor

Microsystem Technologies - “Zero drift” behavior of an optical intraocular pressure sensor is studied using an analytical model based on the deflection of a circular membrane. Results...     

An evaluation of web-based voting usability and accessibility

Several countries are considering web-based voting as an alternative to, or a replacement of, traditional voting methods. It is argued that electronic voting could increase voter participation and help strengthen democracy, as e-voting would increase accessibility for large sections of the population, particularly with regard to groups that previously have experienced difficulties with the traditional voting setup. With a focus on usability and accessibility, this paper reports on a study evaluating several electronic voting prototypes in Norway, involving technical aspects as well as expert evaluation and user testing in the field, with users from a wide range of disabled user groups participating in the study. Technical testing regarding accessibility standard compliance, testing with the personas method and user testing revealed that many rather basic universal design principles were either not fully understood or not prioritized for implementation by the solution providers. However, despite various accessibility difficulties, the participants generally showed a positive attitude towards web-based elections. Through the findings of this study, the authors highlight factors that are important to consider in the development and testing of web-based voting systems.     

Positive state‐bounding observer for positive interval continuous‐time systems with time delay

This paper is concerned with the problem of positive observer synthesis for positive systems with both interval parameter uncertainties and time delay. Conventional observers may no longer be applicable for such kind of systems due to the positivity constraint on the observers, and they only provide an estimate of the system state in an asymptotic way. A pair of positive observers with state‐bounding feature is proposed to estimate the state of positive systems at all times in this paper. A necessary and sufficient condition for the existence of desired observers is first established, and the observer matrices can be obtained easily through the solutions of a set of linear matrix inequalities (LMIs). Then, to reduce the error signal between the system state and its estimates, an iterative LMI algorithm is developed to compute the optimized state‐bounding observer matrices. Finally, a numerical example is presented to show the effectiveness and applicability of the theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.     

A propositional probabilistic logic with discrete linear time for reasoning about evidence

The aim of the paper is to present a sound, strongly complete and decidable probabilistic temporal logic that can model reasoning about evidence. The formal system developed here is actually a solution of a problem proposed by Halpern and Pucella (J Artif Intell Res 26:1–34, 2006).     

Using column generation to solve parallel machine scheduling problems with minmax objective functions

In this paper we consider the parallel machine scheduling problem of minimizing an objective function of the minmax type, like maximum lateness, subject to release dates, deadlines, and/or generalized precedence constraints. We use a destructive strategy to compute a lower bound. Here we test the feasibility of a decision problem by applying column generation to compute a bound on the number of machines that we need to feasibly accommodate all jobs. After having derived the lower bound, we try to find a matching upper bound by identifying a feasible schedule with objective function value equal to this lower bound. Our computational results show that our lower bound is so strong that this is almost always possible. We are able to solve problems with up to 160 jobs and 10 machines in 10 minutes on average.