LFTK: Handcrafted Features in Computational Linguistics

Past research has identified a rich set of handcrafted linguistic features that can potentially assist various tasks. However, their extensive number makes it difficult to effectively select and utilize existing handcrafted features. Coupled with the problem of inconsistent implementation across research works, there has been no categorization scheme or generally-accepted feature names. This creates unwanted confusion. Also, most existing handcrafted feature extraction libraries are not open-source or not actively maintained. As a result, a researcher often has to build such an extraction system from the ground up. We collect and categorize more than 220 popular handcrafted features grounded on past literature. Then, we conduct a correlation analysis study on several task-specific datasets and report the potential use cases of each feature. Lastly, we devise a multilingual handcrafted linguistic feature extraction system in a systematically expandable manner. We open-source our system for public access to a rich set of pre-implemented handcrafted features. Our system is coined LFTK and is the largest of its kind. Find it at github.com/brucewlee/lftk.Comment: BEA @ ACL 202

Operationalizing Goal Directedness: An Empirical Route to Advancing a Philosophical Discussion

Goal directedness is one of the most commonly observed behavior patterns in biology, exemplified by systems ranging in complexity from cellular migration to human motivations. Philosophers have long tried to understand goal directedness in terms of necessary and sufficient conditions, but no consensus has been reached. Here we take an entirely novel approach to goal directedness, postponing the search for necessary and sufficient conditions, and instead trying to advance understanding by an empirical route. In particular, we introduce quantitative measures of goal directedness, applicable to systems that are generally agreed to be goal directed. The measures allow one to assess two signature properties of goal-directed systems, persistence and plasticity. Persistence is the tendency for an entity that is on a trajectory toward a goal to return to that trajectory following perturbations. Plasticity we understand as the tendency for an entity to find a trajectory toward a goal from a variety of different starting distances. We demonstrate the metrics by applying them to goal-directed behavior in two biological systems, bacteria moving up a chemoattractant gradient and a human following a heat gradient. Our approach reveals goal directedness to be an empirically tractable notion, one that makes possible a variety of comparative studies in biology, including comparing degree of goal directedness in different species, or in one species under different conditions, as well as studying evolutionary trends. More generally, the metrics make it possible to investigate the correlates and causes of goal-directed behavior. Finally, our approach challenges the conventional view of goal directedness as a discrete and unitary property, by showing that it can be treated as continuous, as a matter of degree, and that it can be broken down into at least two, and possibly more, partly independent components

Dependence of quantum-Hall conductance on the edge-state equilibration position in a bipolar graphene sheet

By using four-terminal configurations, we investigated the dependence of longitudinal and diagonal resistances of a graphene p-n interface on the quantum-Hall edge-state equilibration position. The resistance of a p-n device in our four-terminal scheme is asymmetric with respect to the zero point where the filling factor ($\nu$) of the entire graphene vanishes. This resistance asymmetry is caused by the chiral-direction-dependent change of the equilibration position and leads to a deeper insight into the equilibration process of the quantum-Hall edge states in a bipolar graphene system.Comment: 5 pages, 4 figures, will be published in PR

A Side-by-side Comparison of Transformers for English Implicit Discourse Relation Classification

Though discourse parsing can help multiple NLP fields, there has been no wide language model search done on implicit discourse relation classification. This hinders researchers from fully utilizing public-available models in discourse analysis. This work is a straightforward, fine-tuned discourse performance comparison of seven pre-trained language models. We use PDTB-3, a popular discourse relation annotated dataset. Through our model search, we raise SOTA to 0.671 ACC and obtain novel observations. Some are contrary to what has been reported before (Shi and Demberg, 2019b), that sentence-level pre-training objectives (NSP, SBO, SOP) generally fail to produce the best performing model for implicit discourse relation classification. Counterintuitively, similar-sized PLMs with MLM and full attention led to better performance.Comment: TrustNLP @ ACL 202

Functional analysis of the fructooligosaccharide utilization operon in \u3ci\u3eLactobacillus paracasei\u3c/i\u3e 1195

The fosABCDXE operon encodes components of a putative fructose/mannose phosphoenolpyruvate-dependent phosphotransferase system (PTS) and a β- fructosidase precursor (FosE) that are involved in the fructooligosaccharide (FOS) utilization pathway of Lactobacillus paracasei 1195. The presence of an N-terminal signal peptide sequence and a LPQAG cell wall anchor motif at the C-terminal region of the deduced FosE precursor amino acid sequence predicted that the enzyme is cell wall-associated, indicating that FOS may be hydrolyzed extracellularly. In this study, cell fractionation experiments demonstrated that the FOS hydrolysis activity was contained exclusively in the cell wall extract of L. paracasei previously grown on FOS. In contrast, no measurable FOS hydrolysis activity was detected in the cell wall extract from the isogenic fosE mutant. Induction of β-fructosidase activity was observed when cells were grown on FOS, inulin, sucrose, or fructose, but not glucose. A diauxic growth pattern was observed when cells were grown on FOS in the presence of limiting glucose (0.1%). Analysis of the culture supernatant revealed that glucose was consumed first, followed by the longer chain FOS species. Transcription analysis further showed that the fos operon was expressed only after glucose was depleted in the medium. Expression of fosE in a non-FOS-fermenting strain, Lactobacillus rhamnosus GG, enabled the recombinant strain to metabolize FOS, inulin, sucrose, and levan

Spin relaxation in mesoscopic superconducting Al wires

We studied the diffusion and the relaxation of the polarized quasiparticle spins in superconductors. To that end, quasiparticles of polarized spins were injected through an interface of a mesoscopic superconducting Al wire in proximity contact with an overlaid ferromagnetic Co wire in the single-domain state. The superconductivity was observed to be suppressed near the spin-injecting interface, as evidenced by the occurrence of a finite voltage for a bias current below the onset of the superconducting transition. The spin diffusion length, estimated from finite voltages over a certain length of Al wire near the interface, was almost temperature independent in the temperature range sufficiently below the superconducting transition but grew as the transition temperature was approached. This temperature dependence suggests that the relaxation of the spin polarization in the superconducting state is governed by the condensation of quasiparticles to the paired state. The spin relaxation in the superconducting state turned out to be more effective than in the normal state.Comment: 9 pages, 8 figure

Quantum Hall resistances of multiterminal top-gated graphene device

Four-terminal resistances, both longitudinal and diagonal, of a locally gated graphene device are measured in the quantum-Hall (QH) regime. In sharp distinction from previous two-terminal studies [J. R. Williams \textit{et al.}, Science {\bf 317}, 638 (2007); B. \"{O}zyilmaz \textit{et al.}, Phys. Rev. Lett. {\bf 99}, 166804 (2007)], asymmetric QH resistances are observed, which provide information on reflection as well as transmission of the QH edge states. Most quantized values of resistances are well analyzed by the assumption that all edge states are equally populated. Contrary to the expectation, however, a 5/2 transmission of the edge states is also found, which may be caused by incomplete mode mixing and/or by the presence of counter-propagating edge states. This four-terminal scheme can be conveniently used to study the edge-state equilibration in locally gated graphene devices as well as mono- and multi-layer graphene hybrid structures.Comment: 6 pages, 4 figures. Typos and equations (2-4) have been corrected. Phys. Rev. B 79, 195327 (2009

Insight into highly conserved H1 subtype-specific epitopes in influenza virus hemagglutinin

Influenza viruses continuously undergo antigenic changes with gradual accumulation of mutations in hemagglutinin (HA) that is a major determinant in subtype specificity. The identification of conserved epitopes within specific HA subtypes gives an important clue for developing new vaccines and diagnostics. We produced and characterized nine monoclonal antibodies that showed significant neutralizing activities against H1 subtype influenza viruses, and determined the complex structure of HA derived from a 2009 pandemic virus A/Korea/01/2009 (KR01) and the Fab fragment from H1-specific monoclonal antibody GC0587. The overall structure of the complex was essentially identical to the previously determined KR01 HA-Fab0757 complex structure. Both Fab0587 and Fab0757 recognize readily accessible head regions of HA, revealing broadly shared and conserved antigenic determinants among H1 subtypes. The beta-strands constituted by Ser110-Glu115 and Lys169-Lys170 form H1 epitopes with distinct conformations from those of H1 and H3 HA sites. In particular, Glu112, Glu115, Lys169, and Lys171 that are highly conserved among H1 subtype HAs have close contacts with HCDR3 and LCDR3. The differences between Fab0587 and Fab0757 complexes reside mainly in HCDR3 and LCDR3, providing distinct antigenic determinants specific for 1918 pdm influenza strain. Our results demonstrate a potential key neutralizing epitope important for H1 subtype specificity in influenza virus