Canonical Examples Research Articles

Pretransitional of behavior of electrooptic Kerr effect in liquid thymol

Melting/freezing are canonical examples of discontinuous phase transitions, for which no pretransitional effects in the liquid phase are expected. For the solid phase, weak premelting effects are evidenced. This report shows long-range, critical-like, pretransitional effects in liquid thymol detected in electrooptic Kerr effect (EKE) studies. Notably is the negative sign of EKE pretransitional anomaly. Studies are supplemented by the high-resolution dielectric constant temperature-related scan, which revealed a weak premelting effect in the solid phase. Both EKE and dielectric constant show a ‘crossover’ change in the liquid phase, ca, 10 K above the freezing temperature. It can be recognized as the hallmark of the challenging liquid–liquid transition phenomenon.Graphical abstract

An implicit conformation tensor decoupling approach for viscoelastic flow simulation within the monolithic projection framework

The highly nonlinear nature of the system governing equations makes it difficult to simulate viscoelastic flows efficiently. In this paper, an implicit decoupling approach is proposed for the viscoelastic flow simulation with a monolithic projection method. The decoupling approach can be derived from the approximate block factorization at the matrix level, which has been successfully applied into the Newtonian flow simulations. In our work, we extend this approach to decouple the pressure, conformation tensor and velocity from the viscoelastic flow system sequentially. Firstly, the pressure-conformation tensor-velocity decoupling is realized by a two-step approximate factorization. By combining the conformation tensor and velocity together at the first-step factorization, the original efficient pressure Poisson solver for the Newtonian flow simulation can be directly adopted in the present framework for non-Newtonian flow simulation. Secondly, the conformation tensor components are further decoupled from each other by the present component-decoupling approach. Then all quantities, including pressure, conformation tensor and velocity, can be resolved without iteration. Additionally, the accuracy corrector is proposed to access the prior scheme limiter-estimation problem introduced by the implicit high-resolution scheme. We numerically demonstrate that all quantities preserve the second-order accuracy in time and space as expected by the theoretical splitting errors. Finally, several different types of canonical benchmark flow examples are conducted to validate the present solver, including laminar flow, turbulent drag-reducing flow and the rotation of a spherical particle immersed in a sheared viscoelastic fluid.

Data-driven discovery of the governing equations of dynamical systems via moving horizon optimization

Discovering the governing laws underpinning physical and chemical phenomena entirely from data is a key step towards understanding and ultimately controlling systems in science and engineering. Noisy measurements and complex, highly nonlinear underlying dynamics hinder the identification of such governing laws. In this work, we introduce a machine learning framework rooted in moving horizon nonlinear optimization for identifying governing equations in the form of ordinary differential equations from noisy experimental data sets. Our approach evaluates sequential subsets of measurement data, and exploits statistical arguments to learn truly parsimonious governing equations from a large dictionary of basis functions. The proposed framework reduces gradient approximation errors by implicitly embedding an advanced numerical discretization scheme, which improves robustness to noise as well as to model stiffness. Canonical nonlinear dynamical system examples are used to demonstrate that our approach can accurately recover parsimonious governing laws under increasing levels of measurement noise, and outperform state of the art frameworks in the literature. Further, we consider a non-isothermal chemical reactor example to demonstrate that the proposed framework can cope with basis functions that have nonlinear (unknown) parameterizations.

Adiabatic soliton management: Controlling solitary wave motion while keeping the wave envelope unchanged

We describe how to control the motion – both speed and propagation direction – of a nonlinear traveling wave in real time via soliton management with time-varying dispersion/diffusion and loss/gain terms. When carried out subject to certain parameter constraints we derive, the approach allows for real-time manipulation of wave motion without compromising the structure or stability of the wave, maintaining strict adiabaticity in time. This makes our approach a promising tool for physical systems which admit a degree of control through adjustable dispersion and loss/gain terms, including problems arising in nonlinear optics, atomic physics, Bose-Einstein condensates, and thermally driven chemical reactions, where one is interested in modifying the position or speed of a wave while still maintaining adiabaticity. We illustrate both the utility and simplicity of the method through several canonical examples, demonstrating how the motion of KdV solitons, Fisher-KPP solitary wavefronts, BBM solitons, nonlinear Klein-Gordon equations, and interacting nonlinear waves in a vector NLS system can be controlled in real time.

Root finding algorithms and persistence of Jordan centrality in growing random trees

We consider models of growing random trees {Tf(n):n≥1} with model dynamics driven by an attachment function f:Z+→R+. At each stage a new vertex enters the system and connects to a vertex v in the current tree with probability proportional to f(degree(v)). The main goal of this study is to understand the performance of root finding algorithms. A large body of work (e.g., Random Structures Algorithms 50 (2017) 158–172; IEEE Trans. Netw. Sci. Eng. 4 (2017) 1–12; Random Structures Algorithms 52 (2018) 136–157) has emerged in the last few years in using techniques based on the Jordan centrality measure (J. Reine Angew. Math. 70 (1869) 185–190) and its variants to develop root finding algorithms. Given an unlabeled unrooted tree, one computes the Jordan centrality for each vertex in the tree and for a fixed budget K outputs the optimal K vertices (as measured by Jordan centrality). Under general conditions on the attachment function f, we derive necessary and sufficient bounds on the budget K(ε) in order to recover the root with probability at least 1−ε. For canonical examples such as linear preferential attachment and uniform attachment, these general results give matching upper and lower bounds for the budget. We also prove persistence of the optimal K Jordan centers for any K, that is, the existence of an almost surely finite random time n∗ such that for n≥n∗ the identity of the K-optimal Jordan centers in {Tf(n):n≥n∗} does not change, thus describing robustness properties of this measure. Key technical ingredients in the proofs of independent interest include sufficient conditions for the existence of exponential moments for limits of (appropriately normalized) continuous time branching processes within which the models {Tf(n):n≥1} can be embedded, as well as rates of convergence results to these limits.

A Fantastic Woman (2017) by Sebastián Lelio: A Transnational Portrait of Transgender Experience

A Fantastic Woman (2017) by Sebastián Lelio: A Transnational Portrait of Transgender Experience Sandra Ortiz-València “Cuando te veo, no sé, no sé lo que veo. Una quimera, eso” (Lelio). This is one of the multiple verbal and physical assaults that Marina, as a trans woman, has to endure while she grieves the recent death of her lover, Orlando. After spending a romantic night together, both rush to the hospital because he has had a heart attack. Unfortunately, he passes away that night. In the days after his sudden death, Marina is forced to confront his family’s objection to their relationship. Before dating Marina, Orlando was married and had a family, and she is seen as a disruptive presence —not just for dating Orlando, but also because she is trans. She is aggressively harassed by Bruno, Orlando’s youngest brother, prevented from attending the funeral, and questioned by the police. No one can comprehend, much less condone, Marina’s existence in Orlando’s life: the fact that she is trans presents challenges to the heteronormative, cis-gendered Chilean society. In rejecting the relationship between Marina and Orlando, society is attempting to deny her the right to grieve the loss of her lover. However, Marina is undeterred. She fights back against the collective rejection in order to reclaim that right. A Fantastic Woman (2017) adds the complexities of transgender experience to a story of loss and grief. The director, Sebastián Lelio —undoubtedly influenced by masters of the classical melodrama, such a Nicolas Ray and Douglas Sirk— constructs a dazzlingly beautiful piece on Marina’s journey that exposes the experiences and struggles transgender individuals encounter on a daily basis. In fact, A Fantastic Woman is part of a trans-national trend in popular culture that has voiced the concerns that affect transgender people and other members of the LGTBIQ+ community. This phenomenon is particularly striking in Latin America, whose cultural production presents a long-lasting literary and cinematic tradition in the representation of non-normative subjects. Two of the most canonical examples would be: El beso de la mujer araña (1976), written by Manuel Puig and adapted to the screen in 1985 by Hector Babencho, and El lugar sin límites (1966) by José Donoso and adapted by Arturo Ripstein in 1978. Of late, Latin American [End Page 33] cultural production has been characterized by an increase in works revolving around LGTBIQ+ issues, as the filmography of Lucía Puenzo, Marco Berger, Diego Lerman, or Lorenzo Vigas illustrates. A Fantastic Woman is a new addition to this cultural trend, one that reached an extraordinary international success, especially after being recognized as the Best Foreign Language Film at the 90th Academy Awards. As Patricia Gherovici puts it: “the word transgender has experienced a ‘meteoric rise’ and [. . .] has become an everyday term” (1). Pieces such as Lelio’s film that deal with transgender issues may seem odd or perverse to some mainstream audiences, given that these works aim to negotiate their conceptualizations of sex, gender, and sexuality within a heterosexual visual framework (Fuchs and Holmlund 4). They row against the tide, but they “unravel identity as a construction,” forcing viewers “to reconsider how we think about other forms of difference” (Ghrerovici 3). Transgender experience pushes forward fluidity as an essential element in identity and “highlight[s] the plasticity, contingency, and arbitrariness of categories like race or gender” (Ghrerovici 5). This is precisely what Lelio’s film does: dismantle traditional heterosexist ideological determinations and pave the way to transform society into a more inclusive and accepting place. By proving that gender identity is a construction, the film lays bare the multiple possibilities for categorizations of sex, gender and sexuality, and calls for an immediate change in social values to protect and respect the multifaceted nature of individual identity. Despite this increasing visibility and presence in the public arena, transgender individuals have little control over their representation, which tends to be instrumentalized and rendered through a voyeuristic lens, rather than one focused on the genuine experiences of these individuals (Gherovici 16). Interestingly, A Fantastic Woman subverts this trend by presenting a story that effectively equates transgender and cisgender heterosexual experiences...

“You don’t know nothin’ bout no Earth, Wind, and Fire”: Reexamining negative concord and definiteness in African American English

AAE is described as exhibiting negative concord, similar to other varieties of English, in which negation licenses c-commanded n-words as well as Negative Polarity Items (NPIs). Crucially, these are thought to be licensed only when the noun phrase they modify is indefinite. Here, our object of study is an under-described phenomenon in AAE: under certain discourse conditions, AAE licenses no before a definite noun phrase (as in “You don't know nothin’ bout no Kendrick Lamar”). We argue that this phenomenon should not be situated in the syntax (as a previously unattested definite n-word), but rather in pragmatics, as speakers “demote” definite NPs to indefinite as part of a discourse strategy of signaling disagreement with, and rejection of, listener assumptions. This has implications for existing analyses of AAE negation, and for cross-dialect comprehension, camouflage constructions, and linguistic ideologies and discrimination. We also revisit existing canonical examples of AAE negation in light of this new analysis (eg., “it ain't no cat can't get in no coop” in Labov 1972).

Ion Channel Partnerships: Odd and Not-So-Odd Couples Controlling Neuronal Ion Channel Function.

The concerted function of the large number of ion channels expressed in excitable cells, including brain neurons, shapes diverse signaling events by controlling the electrical properties of membranes. It has long been recognized that specific groups of ion channels are functionally coupled in mediating ionic fluxes that impact membrane potential, and that these changes in membrane potential impact ion channel gating. Recent studies have identified distinct sets of ion channels that can also physically and functionally associate to regulate the function of either ion channel partner beyond that afforded by changes in membrane potential alone. Here, we review canonical examples of such ion channel partnerships, in which a Ca2+ channel is partnered with a Ca2+-activated K+ channel to provide a dedicated route for efficient coupling of Ca2+ influx to K+ channel activation. We also highlight examples of non-canonical ion channel partnerships between Ca2+ channels and voltage-gated K+ channels that are not intrinsically Ca2+ sensitive, but whose partnership nonetheless yields enhanced regulation of one or the other ion channel partner. We also discuss how these ion channel partnerships can be shaped by the subcellular compartments in which they are found and provide perspectives on how recent advances in techniques to identify proteins in close proximity to one another in native cells may lead to an expanded knowledge of other ion channel partnerships.

Electromagnetic Modeling of Lossy Materials With a Potential-Based Boundary Element Method

The boundary element method (BEM) enables solving three-dimensional electromagnetic problems using a two-dimensional surface mesh, making it appealing for applications ranging from electrical interconnect analysis to the design of metasurfaces. The BEM typically involves the electric and magnetic fields as unknown quantities. Formulations based on electromagnetic potentials rather than fields have garnered interest recently, for two main reasons: (a) they are inherently stable at low frequencies, unlike many field-based approaches, and (b) potentials provide a more direct interface to quantum physical phenomena. Existing potential-based formulations for electromagnetic scattering have been proposed primarily for perfect conductors. We develop a potential-based BEM formulation which can capture both dielectric and conductive losses, and accurately models the skin effect over broad ranges of frequency. The accuracy of the proposed formulation is validated through canonical and realistic numerical examples.

Sonnet and Epic Poems as Forms of Contemporary Slovenian Poetry

In the article on the example of the works by outstanding poets Milan Jesih and Boris A. Novak, are considered the current trends and artistic phenomena of contemporary Slovenian versification. Both authors remain faithful to the traditional genre types and forms of the classical poetic paradigm are the sonnet and the epic poems. The sonnet is Jesih’s calling card (the collections “Soneti”, 1989, and “Soneti drugi”, 1993); Novak’s work has recently been associated with the epic (the trilogy “Vrata nepovrata: epos”, 2015–2017). Slovenian poets are distinguished not only by their adherence to the canonical examples of world literature, but also by their innovative attitude towards them, the desire for their transformation and renewal, as well as the active promotion of this approach.

Exact Solutions of Interacting Dissipative Systems via Weak Symmetries.

We demonstrate how the presence of continuous weak symmetry can be used to analytically diagonalize the Liouvillian of a class of Markovian dissipative systems with strong interactions or nonlinearity. This enables an exact description of the full dynamics and dissipative spectrum. Our method can be viewed as implementing an exact, sector-dependent mean-field decoupling, or alternatively, as a kind of quantum-to-classical mapping. We focus on two canonical examples: a nonlinear bosonic mode subject to incoherent loss and pumping, and an inhomogeneous quantum Ising model with arbitrary connectivity and local dissipation. In both cases, we calculate and analyze the full dissipation spectrum. Our method is applicable to a variety of other systems, and could provide a powerful new tool for the study of complex driven-dissipative quantum systems.

A comprehensive review on Bi2Te3‐based thin films: Thermoelectrics and beyond

AbstractBi2Te3‐based materials are not only the most important and widely used room temperature thermoelectric (TE) materials but are also canonical examples of topological insulators in which the topological surface states are protected by the time‐reversal symmetry. High‐performance thin films based on Bi2Te3 have attracted worldwide attention during the past two decades due primarily to their outstanding TE performance as highly efficient TE coolers and as miniature and flexible TE power generators for a variety of electronic devices. Moreover, intriguing topological phenomena, such as the quantum anomalous Hall effect and topological superconductivity discovered in Bi2Te3‐based thin films and heterostructures, have shaped research directions in the field of condensed matter physics. In Bi2Te3‐based films and heterostructures, delicate control of the carrier transport, film composition, and microstructure are prerequisites for successful device operations as well as for experimental verification of exotic topological phenomena. This review summarizes the recent progress made in atomic defect engineering, carrier tuning, and band engineering down to a nanoscale regime and how it relates to the growth and fabrication of high‐quality Bi2Te3‐based films. The review also briefly discusses the physical insight into the exciting field of topological phenomena that were so dramatically realized in Bi2Te3‐ and Bi2Se3‐based structures. It is expected that Bi2Te3‐based thin films and heterostructures will play an ever more prominent role as flexible TE devices collecting and converting low‐level (body) heat into electricity for numerous electronic applications. It is also likely that such films will continue to be a remarkable platform for the realization of novel topological phenomena.

Invariant Differential Forms on Complexes of Graphs and Feynman Integrals

We study differential forms on an algebraic compactification of a moduli space of metric graphs. Canonical examples of such forms are obtained by pulling back invariant differentials along a tropical Torelli map. The invariant differential forms in question generate the stable real cohomology of the general linear group, as shown by Borel. By integrating such invariant forms over the space of metrics on a graph, we define canonical period integrals associated to graphs, which we prove are always finite and take the form of generalised Feynman integrals. Furthermore, canonical integrals can be used to detect the non-vanishing of homology classes in the commutative graph complex. This theory leads to insights about the structure of the cohomology of the commutative graph complex, and new connections between graph complexes, motivic Galois groups and quantum field theory.

Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs

Abstract The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of “simple stellar populations” into the so-called “multiple stellar populations” (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence of MPs is determined by cluster age. In this article, we use deep photometry from the Hubble Space Telescope to investigate whether the FG-type dwarfs in the ∼1.7 Gyr old cluster NGC 1846, have helium spread. By comparing the observation with the synthetic stellar populations, we estimate a helium spread of ΔY ∼ 0.01 ± 0.01 among the main-sequence stars in NGC 1846. The maximum helium spread would not exceed ΔY ∼ 0.02, depending on the adopted fraction of helium-enriched stars. To mask the color variation caused by such a helium enrichment, a nitrogen enrichment of at least Δ[N/Fe] = 0.8 dex is required, which is excluded by previous analyses of the red-giant branch in this cluster. We find that our result is consistent with the ΔY–mass relationship for Galactic globular clusters. To examine whether or not NGC 1846 harbors MPs, higher photometric accuracy is required. We conclude that under the adopted photometric quality, there is no extreme helium variation among NGC 1846 dwarfs.

Fairness Under Feature Exemptions: Counterfactual and Observational Measures

With the growing use of machine learning algorithms in highly consequential domains, the quantification and removal of disparity in decision making with respect to protected attributes, such as gender, race, etc., is becoming increasingly important. While quantifying disparity is essential, sometimes the needs of a business (e.g., hiring) may require the use of certain features that are critical in a way that any disparity that can be explained by them might need to be exempted. For instance, in hiring a software engineer for a safety-critical application, a coding-test score may be a critical feature that is weighed strongly in the decision even if it introduces disparity, whereas other features, such as name, zip code, or reference letters may be used to improve decision-making, but only to the extent that they do not add disparity. In this work, we propose a novel information-theoretic decomposition of the total disparity (a quantification inspired from counterfactual fairness) into two components: a non-exempt component which quantifies the part of the disparity that cannot be accounted for by the critical features, and an exempt component which quantifies the remaining disparity. This decomposition is important: it allows one to check if the disparity arose purely due to the critical features (inspired from the business necessity defense of disparate impact law) and also enables selective removal of the non-exempt component of disparity if desired. We arrive at this decomposition through canonical examples that lead to a set of desirable properties (axioms) that any measure of non-exempt disparity should satisfy. We then demonstrate that our proposed counterfactual measure of non-exempt disparity satisfies all of them. Our quantification bridges ideas of causality, Simpson's paradox, and a body of work from information theory called Partial Information Decomposition (PID). We also obtain an impossibility result showing that no observational measure of non-exempt disparity can satisfy all of the desired properties, which leads us to relax our goals and examine alternative observational measures that satisfy only some of these properties. We perform case studies to show how one can audit existing models as well as train new models while reducing non-exempt disparity.

Equation-free patch scheme for efficient computational homogenisation via self-adjoint coupling

Equation-free macroscale modelling is a systematic and rigorous computational methodology for efficiently predicting the dynamics of a microscale complex system at a desired macroscale system level. In this scheme, a given microscale model is computed in small patches spread across the space-time domain, with patch coupling conditions bridging the unsimulated space. For accurate predictions, care must be taken in designing the patch coupling conditions. Here we construct novel coupling conditions which preserve self-adjoint symmetry, thus guaranteeing that the macroscale model maintains some important conservation laws of the original microscale model. Consistency of the patch scheme’s macroscale dynamics with the original microscale model is proved for systems in 1D and 2D space, and these proofs immediately extend to higher dimensions. Expanding from a system with a single configuration to an ensemble of configurations establishes that the proven consistency also holds for cases where the microscale periodicity does not integrally fill the patches. This new self-adjoint patch scheme provides an efficient, flexible, and accurate computational homogenisation, as demonstrated here with canonical examples in 1D and 2D space based on heterogenous diffusion, and is applicable to a wide range of multiscale scenarios of interest to scientists and engineers.

In Vitro Studies Reveal that Pseudomonas, from Odontotermes obesus Colonies, can Function as a Defensive Mutualist as it Prevents the Weedy Fungus While Keeping the Crop Fungus Unaffected.

Insects that farm monocultures of fungi are canonical examples of nutritional symbiosis as well as independent evolution of agriculture in non-human animals. But just like in human agriculture, these fungal crops face constant threat of invasion by weeds which, if unchecked, take over the crop fungus. In fungus-growing termites, the crop fungus (Termitomyces) faces such challenges from the weedy fungusPseudoxylaria.The mechanism by whichPseudoxylariais suppressed is not known. However, evidence suggests that some bacterial secondary symbionts can serve as defensive mutualists by preventing the growth ofPseudoxylaria.However, such secondary symbionts must possess the dual, yet contrasting, capabilities of suppressing the weedy fungus while keeping the growth of the crop fungus unaffected. This study describes the isolation, identification, and culture-dependent estimation of the roles of several such putative defensive mutualists from the colonies of the wide-spread fungus-growing termitefrom India,Odontotermesobesus. From the 38 bacterial cultures tested, a strain of Pseudomonas showed significantly greater suppression of the weedy fungus than the crop fungus. Moreover, a 16SrRNApan-microbiome survey, using the Nanopore platform, revealedPseudomonasto be a part of the core microbiota ofO. obesus. A meta-analysis of microbiota composition across different species of Odontotermesalso confirms the widespread prevalence ofPseudomonaswithin this termite. These lines of evidence indicate that Pseudomonascould be playing the role of defensive mutualist withinOdontotermes.

Flat-band solutions in D -dimensional decorated diamond and pyrochlore lattices: Reduction to molecular problem

Flat-band models have been of particular interest from both fundamental aspects and realization in materials. Beyond the canonical examples such as Lieb lattices and line graphs, a variety of tight-binding models are found to possess flat bands. However, analytical treatment of dispersion relations is limited, especially when there are multiple flat bands with different energies. In this paper, we present how to determine flat-band energies and wave functions in tight-binding models on decorated diamond and pyrochlore lattices in generic dimensions $D \geq 2$. For two and three dimensions, such lattice structures are relevant to various organic and inorganic materials, and thus our method will be useful to analyze the band structures of these materials.

Ancient Latin grammarians on suppletion

Abstract The term “suppletion”, introduced by Osthoff (1899. Vom Suppletivwesen der indogermanischen Sprachen. Heidelberg: Universitätsbuchdruckerei Hörning), was traditionally used to refer to an inflectional paradigm containing forms based on two or more etymologically different stems. In the last decades, however, it has been argued that etymology does not contribute to our understanding of the phenomenon, and it should be strictly defined on synchronic terms: simply as the peak point on the formal irregularity scale, regardless of the actual origin of the irregularity. Under this approach, all forms reported by speakers as two potentially different lexical items are considered to be suppletive. To be able to determine what users of a living language consider to be a case of suppletion, it is possible to analyze data collected from speakers. The situation is considerably more difficult for dead languages, which however have played an important role in the debate and provided many of the canonical examples. As a closest equivalent to eliciting the required information from a native speaker, the informed but from the present-day perspective naïve expressions of linguistic introspection in the works of Late Latin Grammarians, namely their use of specific terms (defectivum, anomalum, inaequale) to refer to different degrees and lexical examples of irregularity, are highly valuable, as it also may reflect the difficulties confronted by non-native learners.

Genre analysis of movies using a topic model of plot summaries

AbstractGenre plays an important role in the description, navigation, and discovery of movies, but it is rarely studied at large scale using quantitative methods. This allows an analysis of how genre labels are applied, how genres are composed and how these ingredients change, and how genres compare. We apply unsupervised topic modeling to a large collection of textual movie summaries and then use the model's topic proportions to investigate key questions in genre, including recognizability, mapping, canonicity, and change over time. We find that many genres can be quite easily predicted by their lexical signatures and this defines their position on the genre landscape. We find significant genre composition changes between periods for westerns, science fiction and road movies, reflecting changes in production and consumption values. We show that in terms of canonicity, canonical examples are often at the high end of the topic distribution profile for the genre rather than central as might be predicted by categorization theory.