Processing profile for quantifiers in verb phrase ellipsis: Evidence for grammatical economy

Quantifier Raising leaves no overt marking to indicate movement has occurred, making the task of identifying when raising has occurred extremely difficult for the parser. Beyond this challenge, evidence from interpretation and judgement studies suggests that raising causes difficulty in processing. These two aspects taken together have led some to suggest that human sentence processor employs a strategy in which the construction of raised structures is avoided, commonly called processing scope economy. This contrasts to the traditional notion of grammatical scope economy, where Quantifier Raising is restricted in the grammar. In this paper we discuss the properties of these two theories. We conclude that the two approaches make different predictions about when raising should occur online, with processing scope economy predicting that the parser avoids raising whenever possible and grammatical scope economy predicting that the parser raises regularly and sometimes produces ungrammatical structures in the process. We then present an experiment which examines complex scope structures in verb phrase ellipsis to observe when penalties related to Quantifier Raising are observed online. We find that penalties appear in configurations where Quantifier Raising would be ungrammatical under grammatical scope economy, suggesting the parser attempts Quantifier Raising in these configurations. This evidence indicates that the parser’s behavior matches the predictions of grammatical scope economy rather than those of processing scope economy

Constraints and Mechanisms in Long-Distance Dependency Formation

This thesis aims to reveal the mechanisms and constraints involving in long-distance dependency formation in the static knowledge of language and in real-time sentence processing. Special attention is paid to the grammar and processing of island constraints. Several experiments show that in a head-final language like Japanese global constraints like island constraints are applied long before decisive information such as verb heads and relative heads, are encountered. Based on this observation, the thesis argues that there is a powerful predictive mechanism at work behind real time sentence processing. A model of this predictive mechanism is proposed. This thesis examines the nature of several island constraints, specifically Complex NP Islands induced by relative clauses, and clausal adjunct islands. It is argued that in the majority of languages, both relative clauses and adjunct clauses are islands, but there is a small subset of languages (including Japanese, Korean and Malayalam) where extraction out of adjunct clauses seems to be allowed. Applying well-established syntactic tests to the necessary constructions in Japanese, it is established that dependencies crossing adjunct clauses are indeed created by movement operations, and still the extraction is allowed from adjuncts. Building on previous findings, the thesis turns to the investigation of the interaction between real time sentence processing and island constraints. Looking specifically at Japanese, a head-final language this thesis ask how the structure of sentences are built and what constraints are applied to the structure building process. A series of experiments shows that in Japanese, even before high-information bearing units such as verbs, relative heads or adjunct markers are encountered, the structural skeleton is built, and such pre-computed structures are highly articulated. It is shown that structural constraints on long-distance dependencies are imposed on the pre-built structure. It is further shown that this finding support the incrementality of sentence processing

Time course of grammatical encoding in agrammatism

Two on-line sentence production experiments explored the time course of grammatical encoding in normal and agrammatic speakers. Incremental models suggest grammatical encoding proceeds in a word-by-word manner, without advanced planning. Structural models suggest a hierarchical predicate structure (e.g., verb argument structure, VAS) is encoded prior to speech onset. Results showed that when agrammatic speakers produced sentences in a pre-defined order, they produced sentences incrementally, similar to controls. However, in a free sentence production task, both controls and agrammatic speakers encoded VAS prior to speech onset. Further, agrammatic speakers’ syntactic deficits resulted in a greater use of VAS than controls

Cataphora processing in agrammatic aphasia: Eye movement evidence for integration deficits

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Processing gapping: Parallelism and grammatical constraints

This study aims to test two hypotheses about the online processing of Gapping: whether the parser inserts an ellipsis site in an incremental fashion in certain coordinated structures (the Incremental Ellipsis Hypothesis), or whether ellipsis is a late and dispreferred option (the Ellipsis as a Last Resort Hypothesis). We employ two offline acceptability rating experiments and a sentence fragment completion experiment to investigate to what extent the distribution of Gapping is controlled by grammatical and extra-grammatical constraints. Furthermore, an eye-tracking while reading experiment demonstrated that the parser inserts an ellipsis site incrementally but only when grammatical and extra- grammatical constraints allow for the insertion of the ellipsis site. This study shows that incremental building of the Gapping structure follows from the parser’s general preference to keep the structure of the two conjuncts maximally parallel in a coordination structure as well as from grammatical restrictions on the distribution of Gapping such as the Coordination Constraint

pXBP1(U) encoded in XBP1 pre-mRNA negatively regulates unfolded protein response activator pXBP1(S) in mammalian ER stress response

Upon the accumulation of unfolded proteins in the mammalian endoplasmic reticulum (ER), X-box binding protein 1 (XBP1) premessenger RNA (premRNA) is converted to mature mRNA by unconventional splicing that is mediated by the endonuclease inositol-requiring enzyme 1. The transcription factor protein (p) XBP1 spliced (S), which is translated from mature XBP1 mRNA, contains the nuclear localization signal and the transcriptional activation domain and activates the transcription of target genes, including those encoding ER chaperones in the nucleus. We show that pXBP1 unspliced (U) encoded in XBP1 pre-mRNA was constitutively expressed and markedly accumulated at the recovery phase of ER stress. pXBP1(U) contained the nuclear exclusion signal instead of the transcriptional activation domain and shuttled between the nucleus and the cytoplasm. Interestingly, pXBP1(U) formed a complex with pXBP1(S), and the pXBP1(U)–pXBP1(S) complex was sequestered from the nucleus. Moreover, the complex was rapidly degraded by proteasomes because of the degradation motif contained in pXBP1(U). Thus, pXBP1(U) is a negative feedback regulator of pXBP1(S), which shuts off the transcription of target genes during the recovery phase of ER stress

Enhancement of protein thermostability by three consecutive mutations using loop-walking method and machine learning

We developed a method to improve protein thermostability, "loop-walking method". Three consecutive positions in 12 loops of Burkholderia cepacia lipase were subjected to random mutagenesis to make 12 libraries. Screening allowed us to identify L7 as a hot-spot loop having an impact on thermostability, and the P233G/L234E/V235M mutant was found from 214 variants in the L7 library. Although a more excellent mutant might be discovered by screening all the 8000 P233X/L234X/V235X mutants, it was difficult to assay all of them. We therefore employed machine learning. Using thermostability data of the 214 mutants, a computational discrimination model was constructed to predict thermostability potentials. Among 7786 combinations ranked in silico, 20 promising candidates were selected and assayed. The P233D/L234P/V235S mutant retained 66% activity after heat treatment at 60 degrees C for 30 min, which was higher than those of the wild-type enzyme (5%) and the P233G/L234E/V235M mutant (35%)