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As a precursor to various reactive nitrogen species formed in biological systems, nitric oxide (•NO) participates in numerous processes, including enhancing DNA radiosensitivity in ionizing radiation-based radiotherapy. Forming guanine radical cations is another common DNA lesion resulting from ionization and oxidation damage. As such, the interaction of •NO with guanine radical cations (G•+) may contribute to the radiosensitization of •NO. An intriguing aspect of this process is the participation of multiple spin configurations in the reaction, including open-shell singlet 1,OS[G•+(↑)⋯(↓)•NO], closed-shell singlet 1,CS[G(↑↓)⋯NO+], and triplet 3[G•+(↑)⋯(↑)•NO]. In this study, the reactions of •NO with both unsubstituted guanine radical cations (in the 9HG•+ conformation) and 9-methylguanine radical cations (9MG•+, a guanosine-mimicking model compound) were investigated in the absence and presence of monohydration of radical cations. Kinetic-energy dependent reaction product ions and cross sections were measured using an electrospray ionization guided-ion beam tandem mass spectrometer. The reaction mechanisms, kinetics, and dynamics were comprehended by interpreting the reaction potential energy surface using spin-projected density functional theory, coupled cluster theory, and multiconfiguration complete active space second-order perturbation theory, followed by RRKM kinetics modeling. The combined experimental and computational findings revealed closed-shell singlet 1,CS[7-NO-9MG]+ as the major, exothermic product and triplet 3[8-NO-9MG]+ as the minor, endothermic product. Singlet biradical products were not detected due to high reaction endothermicities, activation barriers, and inherent instability. [ABSTRACT FROM AUTHOR]

Over 60 years of studying morphological stability under fundamental ideas of William Wilson Mullins and Robert Floyd Sekerka [J. Appl. Phys. 34, 323 (1963) and J. Appl. Phys. 35, 444 (1964)] it has become possible to explain the origin and selection of surface structures from planar to cellular, dendritic, and fractal patterns. The Mullins–Sekerka (MS) morphological instability theory provides a condition for stability or reconstruction of interfaces, which separates the phases during phase transformation. The MS-theory has come a long way in the conceptual understanding of the incipience of morphological instability and the formation of structures, although today, certain aspects of this theory continue to be discussed at the fundamental and quantitative level of its interpretation. In the sixtieth anniversary of this theory, we re-examine the MS-analysis under boundary conditions satisfying the smooth existence of temperature and its gradients in directional crystallization of a binary melt. These boundary conditions are dependent on the finite distance from the solidification front for providing directional solidification that quantitatively affects the amplification rate of perturbations in the solid–liquid front morphology. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine the reliability and agreement of manual and automated morphological measurements, and agreement in morphological diagnoses. METHODS: Thirty pelvic radiographs were randomly selected from the World COACH consortium. Manual and automated measurements of acetabular depth-width ratio (ADR), modified acetabular index (mAI), alpha angle (AA), Wiberg center edge angle (WCEA), lateral center edge angle (LCEA), extrusion index (EI), neck-shaft angle (NSA), and triangular index ratio (TIR) were performed. Bland-Altman plots and intraclass correlation coefficients (ICCs) were used to test reliability. Agreement in diagnosing acetabular dysplasia, pincer and cam morphology by manual and automated measurements was assessed using percentage agreement. Visualizations of all measurements were scored by a radiologist. RESULTS: The Bland-Altman plots showed no to small mean differences between automated and manual measurements for all measurements except for ADR. Intraobserver ICCs of manual measurements ranged from 0.26 (95%-CI 0-0.57) for TIR to 0.95 (95%-CI 0.87-0.98) for LCEA. Interobserver ICCs of manual measurements ranged from 0.43 (95%-CI 0.10-0.68) for AA to 0.95 (95%-CI 0.86-0.98) for LCEA. Intermethod ICCs ranged from 0.46 (95%-CI 0.12-0.70) for AA to 0.89 (95%-CI 0.78-0.94) for LCEA. Radiographic diagnostic agreement ranged from 47% to 100% for the manual observers and 63%-96% for the automated method as assessed by the radiologist. CONCLUSION: The automated algorithm performed equally well compared to manual measurement by trained observers, attesting to its reliability and efficiency in rapidly computing morphological measurements. This validated method can aid clinical practice and accelerate hip osteoarthritis research.

Chiral hybrid lead halide perovskites show interesting chiral optoelectronic properties. The extent of chirality is often estimated by their circular dichroism (CD) response. Here, we show that the CD data depend strongly on film morphology. Four of the six chiral hybrid lead halide films prepared, 2D (R- and S-MBA)2PbI4 and 1D (R- and S-MBA)PbI3 (MBA: methylbenzylammonium), form homogenous non-textured films and show an isotropic CD signal. In contrast, the other two samples, 1D (R- and S-MBA)PbBr3, form textured films, showing uncorrelated CD signals from different parts of the film. Therefore, the role of film morphology needs to be verified before designing and comparing the chiroptic and chiral optoelectronic properties of hybrid perovskites. [ABSTRACT FROM AUTHOR]

The phase behavior of block copolymers (BCPs) at the water-oil interface is influenced by the segmental interaction parameter ( χ${\chi }$ ) and chain architecture. We synthesized a series of star block copolymers (s-BCPs) having polystyrene (PS) as core and poly(2-vinylpyridine) (P2VP) as corona. The interaction parameters of block-block ( χ${\chi }$ PS-P2VP ) and block-solvent ( χ${\chi }$ P2VP-solvent ) were varied by adjusting the pH of the aqueous solution. Lowering pH increased the fraction of quaternized-P2VP (Q-P2VP) with enhanced hydrophilicity. By transferring the equilibrated interfacial assemblies, morphologies ranging from bicontinuous films at pH of 7 and 3.1 to nanoporous and nanotubular structure at pH of 0.65 were observed. The nanoporous films formed hexagonally packed pores in s-BCP matrix, while nanotubes comprised Q-P2VP as corona and PS as core. Control over pore size, d-spacing between pores, and nanotube diameters was achieved by varying polymer concentration, molecular weight, volume fraction and arm number of s-BCPs. Large-scale nanoporous films were obtained by freeze-drying emulsions. Remarkably, the morphologies of linear BCPs were inverted, forming hexagonal-packed rigid spherical micelles with Q-P2VP as core and PS as corona in multilayer. This work provides insights of phase behaviors of BCP at fluids interface and offer a facile approach to prepare nanoporous film with well-controlled pore structure.

Strongyloides stercoralis, commonly known as the human threadworm, is a skin-penetrating gastrointestinal parasitic nematode that infects hundreds of millions of people worldwide. Like other Strongyloides species, S. stercoralis is capable of cycling through a single free-living generation. Although S. stercoralis and the free-living nematode Caenorhabditis elegans are evolutionarily distant, the free-living adults of S. stercoralis are similar enough in size and morphology to C. elegans adults that techniques for generating transgenics and knockouts in C. elegans have been successfully adapted for use in S. stercoralis. High-quality genomic and transcriptomic data are also available for S. stercoralis. Thus, one can use a burgeoning array of functional genomic tools in S. stercoralis to probe questions about parasitic nematode development, physiology, and behavior. Knowledge gained from S. stercoralis will inform studies of other parasitic nematodes such as hookworms that are not yet amenable to genetic manipulation. This review describes the basic anatomy of S. stercoralis.

This paper provides an overview of Pangkhua, a South Central Tibeto-Burman (Kuki-Chin) language of Bangladesh. Pangkhua is an underdocumented and a largely endangered language spoken by about 2000 people in Rangamati District, Chittagong Hill Tracts, Bangladesh. In this overview, first, I examine Pangkhua’s position in the internal subclassifications of the South Central subgroup and show that its position in the subgroup is not as obvious as has often been regarded. Then, I discuss some of Pangkhua’s basic and typologically important characteristics including phonology, morphology, and syntax. As a first account of Pangkhua, this overview will facilitate areal-typological as well as historical and comparative South Central Tibeto-Burman linguistics research.

English allows for both compounds (e.g., London-made) and phrasal paraphrases (e.g., made in London). While these constructions have roughly the same truth-conditional meaning, we hypothesize that the compound allows less freedom to express the nature of the semantic relationship between the participle and the pre-participle nominal. We thus predict that the pre-participle slot is more constrained than the equivalent position in the phrasal construction. We test this prediction in a large corpus by measuring the entropy of corresponding nominal slots, conditional on the participle used. That is, we compare the entropy of α in compound construction slots like “α-[V]ed” to the entropy of α in phrasal constructions like “[V]ed by α” for a given verb V. As predicted, there is significantly lower entropy in the compound construction than in the phrasal construction. We consider how these predictions follow from more general grammatical properties and processing factors.

Languages spoken in larger populations seem to be relatively simple. One possible explanation is that this is a consequence of the simplifying influence of non-native speakers: adult learners tend to reduce complexity during learning, and large languages tend to have a higher proportion of non-native speakers. This Linguistic Niche Hypothesis, that languages adapt to their social niche, receives some statistical support from typological studies which show negative correlations between population size or number of non-native speakers and morphological complexity. Here I report an experimental test of this hypothesis, using two artificial language learning experiments to explore the impact of simplifications made by non-native-like early learners on morphological complexity. These experiments show that the presence of non-native-like early learners in a population can lead to the simplification of that language's morphology as a result of inter-generational language transmission, providing experimental support for the Linguistic Niche Hypothesis.

This paper tests the similarity in neural responses across repeated words and morphosyntactic features both within and between two languages. Prior work using priming has revealed robust cross-linguistic lexical effects and effects for shared grammatical form, such as argument structure; these methods have been less successful when applied to morphosyntactic features. Combining machine-learning based neural decoding with EEG data collected from Korean-English bilinguals we, first, replicate prior work showing successful classification of lexical items from EEG signals. We then extend this to demonstrate successful classification of morphosyntactic features of number and tense. Finally, we find that EEG decoding in one language does not successfully generalize to another, even when temporal differences are considered. Taken together, these results point to stable EEG representations for lexical items and morphosyntactic features, but suggest that these representations are different between the two languages investigated here.

Homophony (i.e, multiple meanings expressed by the same form) is ubiquitous across the world's languages. Despite its pervasiveness, not all instances of homophony are equally likely, which suggests that homophony is unlikely to be accidental. There is a growing body of literature which aims to thoroughly examine cross-linguistic regularities in patterns of homophony and explain these from constraints in language learning and use, both at the lexical and morphosyntactic levels. Here, we examine a specific case of homophony in pronominal paradigms, that is, the lack of a number distinction (singular vs plural) for a given person value (first, second and third), a phenomenon coined as horizontal homophony. Cysouw (2003) suggested that a lack of number distinction is more likely to be found in third person (i.e., 3SG=3PL) than in second (i.e., 2SG=2PL), and it is least frequently found in first person (i.e., 1SG=1PL). We refer to this generalisation as the Horizontal Homophony Hierarchy: 3 > 2 > 1 (where > represents frequency inequality). This generalisation was nevertheless only made via qualitative description and by raw counts, and merely described without motivated explanation. In this study we take a step back and present additional evidence supporting the Horizontal Homophony Hierarchy. First, we ascertain the robustness of this typological tendency through a statistical analysis using the largest cross-linguistic database of pronominal paradigms to date (926 languages from 229 different families). Next, we explore whether the Horizontal Homophony Hierarchy has a corresponding learning correlate, which would indicate that this asymmetry is at least partly rooted in a cognitive bias. Specifically, we examine asymmetries in how easily adult humans learn different types of horizontal homophony in an artificial language learning experiment. The results from our typological analysis corroborate a hierarchy of horizontal homophony 3 > 2 > 1 in the world's languages. However, our experimental results provide evidence against a learning bias underlying the hierarchy, thus suggesting that motivated explanations of the typology (if any) are more likely to be found in alternative pressures such as communicative need and efficiency.

In this study we investigated the role of interword spacing and its interaction with Arabic root frequencies by studying readers' eye movement patterns when they read Arabic sentences. Our eye-tracking experiment results did not show any significant evidence for the interword spacing effect on Arabic word processing, which concurred with the earlier work by Leung et al. (2021). On the other hand, we replicated an earlier experiment conducted by Hermena et al. (2020) on the effect of Arabic root frequencies on word processing. Contrary to their finding, our results showed that words which differed in root frequencies significantly modulated eye movement measures. This provided another support to the status of Arabic non-concatenative roots as a morphological unit.

Learning to understand and use agreement is an integral part of children's linguistic development. In Romance languages, this includes gender and number agreement between the controller and attributive or predicative adjectives or participles. We examine the development of this category in a case where children's task is complicated by syncretisms, multiple paradigms, and unequal input distributions. Romansh Tuatschin (Romance, Indo-European, Switzerland) presents children with two distinct paradigms for attributive (masculine and feminine only) and predicative (masculine, feminine, and neuter/unmarked) contexts of adjective and participle use. The masculine form in predicative use is the same as the neuter form in attributive usage. Thus the masculine form in these two paradigms differs. This could be challenging for the language learner. The distribution of these forms is heavily skewed towards the \emph{neuter} in predicative contexts but balanced in attributives. Examining production errors in children between 2;0 and 4;3, we evaluate the effects of frequency and syncretism and find that error-rate is affected by skewed distributions and less affected by syncretisms. This demonstrates the strong effect of input distributions on first language acquisition.

Most Chinese words are compounds formed through the combination of meaningful characters. Yet, due to compositional complexity, it is poorly understood how this combinatorial process affects the access to the whole-word meaning. In the present study, we turned to the recent development in compositional distributional semantics (Marelli et al., 2017), and employed a deep neural network to learn the less-than-systematic relationship between the constituent characters and the compound words. Based on the compositional representations derived from the computational model, we quantified compositionality as the degree of overlap between the compositional and the lexicalized representations as well as the degree of distinctness of the compositional representation. We observed that these two compositional attributes can affect compound recognition over and above the effects of constituent character features and compound features. Moreover, we found that this effect was increasingly stronger when holistic access to the compound meaning became more challenging. These findings therefore, from a computational perspective, provided new evidence for the combinatorial process involved in Chinese word recognition, which also shed light on the universal process of compound comprehension.

Animacy is prevalent in as a semantic basis for noun classification systems (i.e., grammatical gender, noun classes and classifiers), but colour is completely absent, despite its visual salience. The absence of colour in such systems is sometimes argued to suggest domain-specific constraints on what is grammatically encodable. Here, we investigate whether this tendency could instead be explained by the superior predictive power of animacy (i.e., the degree to which it predicts other features) compared to colour. In a series of experiments, we find that animacy-based noun classes are learned better than colour-based ones. However, when participants are encouraged, by manipulating predictive power, to sort images based on colour, they are worse at learning animacy-based noun classes. The results suggest the animacy bias in grammar may have its roots in domain-general categorisation principles. They further serve as evidence for the role of cognitive biases in constraining cross-linguistic variation.