A Study of Extracting Related Documents for Essay Evaluation Modules

本研究では，小論文採点システムにおいて必要となる小論文に関連した文書を取得する方法を開発した．本研究プロジェクトの自動採点の評価軸の1 つに「妥当性」がある．妥当性の評価手法として，小論文の内容がWikipediaの文書の内容と，どの程度一致しているかを基準に妥当性スコアを算出する方法を考えている．しかし，Wikipediaの文書は多様であり，小論文で取り上げていない議題に関する文書も多く存在する．そこで本論文では小論文ごとに適切な文書を取得する方法を提案する．いくつかの手法を試した結果，単語ベクトルを使用した方法が，関連した文書を獲得することができたことを報告する．We are developing an automatic Japanese essay-scoring system that is composed of 4 evaluation criteria, comprehensiveness, logical consistency, validity, spelling and grammar. In this paper, we discuss the most powerful approach to extract documents of Wikipedia that relates to the reference texts of the target essay theme for validity evaluation. The reason for using Wikipedia documents for evaluating validity of students’essays is that we assume that validity can be evaluated by the expanded discussions in Wikipedia documents that relates to the essay theme. Experimental results show that the skip-gram based word vector is the best approach to extract relating documents to reference texts among several keyword-based evaluation approaches

Proposing an Unsupervised Approach to Evaluate Essays Using IDF on Reference Data

大学入試において2020 年から記述式問題が導入されることから記述式の問題を自動で採点する手法の開発が求められている．本論では，エッセイタイプの小論文課題を対象に，課題に関連する参照データとWikipedia 全文から作成したidf を利用した事前採点不要な自動採点手法を提案する．先行研究において，日本語小論文を対象とした自動採点では，多くの事前採点が必要となり，実際の数百人規模の試験では利用することが難しいと考えられる．そこで本研究では，事前採点が不要な小論文採点手法を提案する．また，小論文の模擬試験を実施して小論文データを構築する．構築した小論文データに対して採点手法を用い，実験を行い評価する．また小論文データの人手による採点に対しても評価を行う．評価実験の結果neologd 辞書を利用した形態素解析器を用いて， idf 値を利用した形態素の一致数が，人手の評価値と相関が高いことを示す．In this paper, we describe an on-going study of developing an automatic essay-scoring system in Japanese. Essay scoring systems have already been developed and used mainly in English, while not many previous studies have been done on Japanese essay evaluations. Most of the methods and systems of automatic essay evaluation need not small number of previously human-graded essays for calibrating the parameter of regression functions or parameter of machine learning. The previous studies show the high performance for essay evaluation task, however, it must be not easy to assume large graded essays in, for example, actual tests or entrance examinations. Thus, we take a approach to evaluate Japanese essays without previously human-graded essays but with assuming reference data related to essay questions. The proposed method is a simple one, that is, evaluating the essays with co-occurrences with the reference data in their words or morphemes. In the method technical terms would be given high scores using neologd dictionary and idf values. Experimental results show that the proposed method works well in our developing Japanese mock trial writing tests. Key words automatic scoring of essays, human annotation, supportin

Nascentome Analysis Uncovers Futile Protein Synthesis in Escherichia coli

Although co-translational biological processes attract much attention, no general and easy method has been available to detect cellular nascent polypeptide chains, which we propose to call collectively a “nascentome.” We developed a method to selectively detect polypeptide portions of cellular polypeptidyl-tRNAs and used it to study the generality of the quality control reactions that rescue dead-end translation complexes. To detect nascent polypeptides, having their growing ends covalently attached to a tRNA, cellular extracts are separated by SDS-PAGE in two dimensions, first with the peptidyl-tRNA ester bonds preserved and subsequently after their in-gel cleavage. Pulse-labeled nascent polypeptides of Escherichia coli form a characteristic line below the main diagonal line, because each of them had contained a tRNA of nearly uniform size in the first-dimension electrophoresis but not in the second-dimension. The detection of nascent polypeptides, separately from any translation-completed polypeptides or degradation products thereof, allows us to follow their fates to gain deeper insights into protein biogenesis and quality control pathways. It was revealed that polypeptidyl-tRNAs were significantly stabilized in E. coli upon dysfunction of the tmRNA-ArfA ribosome-rescuing system, whose function had only been studied previously using model constructs. Our results suggest that E. coli cells are intrinsically producing aberrant translation products, which are normally eliminated by the ribosome-rescuing mechanisms

Ribosome rescue activity of an Arabidopsis thaliana ArfB homolog

A homolog of the bacterial ribosome rescue factor ArfB was identified in Arabidopsis thaliana. The factor, named AtArfB for Arabidopsis thaliana ArfB, showed ribosome rescue activity in both in vivo and in vitro assays based on the bacterial translation system. As has been shown for ArfB, the ribosome rescue activity of AtArfB was dependent on the GGQ motif, the crucial motif for the function of class I release factors and ArfB. The C-terminal region of AtArfB was also important for its function. The N-terminal region of AtArfB, which is absent in bacterial ArfB, functioned as a transit peptide for chloroplast targeting in tobacco cells. These results strongly suggest that AtArfB is a ribosome rescue factor that functions in chloroplasts

Two DNA Invertases Contribute to Flagellar Phase Variation in Salmonella enterica Serovar Typhimurium Strain LT2

Salmonella enterica serovar Typhimurium strain LT2 possesses two nonallelic structural genes, fliC and fljB, for flagellin, the component protein of flagellar filaments. Flagellar phase variation occurs by alternative expression of these two genes. This is controlled by the inversion of a DNA segment, called the H segment, containing the fljB promoter. H inversion occurs by site-specific recombination between inverted repetitious sequences flanking the H segment. This recombination has been shown in vivo and in vitro to be mediated by a DNA invertase, Hin, whose gene is located within the H segment. However, a search of the complete genomic sequence revealed that LT2 possesses another DNA invertase gene that is located adjacent to another invertible DNA segment within a resident prophage, Fels-2. Here, we named this gene fin. We constructed hin and fin disruption mutants from LT2 and examined their phase variation abilities. The hin disruption mutant could still undergo flagellar phase variation, indicating that Hin is not the sole DNA invertase responsible for phase variation. Although the fin disruption mutant could undergo phase variation, fin hin double mutants could not. These results clearly indicate that both Hin and Fin contribute to flagellar phase variation in LT2. We further showed that a phase-stable serovar, serovar Abortusequi, which is known to possess a naturally occurring hin mutation, lacks Fels-2, which ensures the phase stability in this serovar

EAL Domain Protein YdiV Acts as an Anti-FlhD4C2 Factor Responsible for Nutritional Control of the Flagellar Regulon in Salmonella enterica Serovar Typhimurium▿

Flagellar operons are divided into three classes with respect to their transcriptional hierarchy in Salmonella enterica serovar Typhimurium. The class 1 gene products FlhD and FlhC act together in an FlhD4C2 heterohexamer, which binds upstream of the class 2 promoters to facilitate binding of RNA polymerase. In this study, we showed that flagellar expression was much reduced in the cells grown in poor medium compared to those grown in rich medium. This nutritional control was shown to be executed at a step after class 1 transcription. We isolated five Tn5 insertion mutants in which the class 2 expression was derepressed in poor medium. These insertions were located in the ydiV (cdgR) gene or a gene just upstream of ydiV. The ydiV gene is known to encode an EAL domain protein and to act as a negative regulator of flagellar expression. Gene disruption and complementation analyses revealed that the ydiV gene is responsible for nutritional control. Expression analysis of the ydiV gene showed that its translation, but not transcription, was enhanced by growth in poor medium. The ydiV mutation did not have a significant effect on either the steady-state level of flhDC mRNA or that of FlhC protein. Purified YdiV protein was shown in vitro to bind to FlhD4C2 through interaction with FlhD subunit and to inhibit its binding to the class 2 promoter, resulting in inhibition of FlhD4C2-dependent transcription. Taking these data together, we conclude that YdiV is a novel anti-FlhD4C2 factor responsible for nutritional control of the flagellar regulon