Euler Characteristic Tools For Topological Data Analysis

In this article, we study Euler characteristic techniques in topological data analysis. Pointwise computing the Euler characteristic of a family of simplicial complexes built from data gives rise to the so-called Euler characteristic profile. We show that this simple descriptor achieve state-of-the-art performance in supervised tasks at a very low computational cost. Inspired by signal analysis, we compute hybrid transforms of Euler characteristic profiles. These integral transforms mix Euler characteristic techniques with Lebesgue integration to provide highly efficient compressors of topological signals. As a consequence, they show remarkable performances in unsupervised settings. On the qualitative side, we provide numerous heuristics on the topological and geometric information captured by Euler profiles and their hybrid transforms. Finally, we prove stability results for these descriptors as well as asymptotic guarantees in random settings.Comment: 39 page

Hope For Syntactic Bootstrapping

We explore children’s use of syntactic distribution in the acquisition of attitude verbs, such as think, want, and hope. Because attitude verbs refer to concepts that are opaque to observation but have syntactic distributions predictive of semantic properties, we hypothesize that syntax may serve as an important cue to learning their meanings. Using a novel methodology, we replicate previous literature showing an asymmetry between acquisition of think and want, and we additionally demonstrate that interpretation of a less frequent attitude verb, hope, patterns with type of syntactic complement. This supports the view that children treat syntactic frame as informative about an attitude verb’s meaning

Finding the force: a novel word learning experiment with modals

This study investigates the semantic and pragmatic challenges of acquiring the force of English modals, which express possibility (e.g., might) and necessity (e.g., must). Children seem to struggle with modal force through at least age 4, over-accepting both possibility modals where adults would prefer necessity modals, and necessity modals in possibility situations. These difficulties are typically blamed on pragmatic or conceptual immaturity. In this study, we sidestep these immaturity issues by investigating the challenges of modal learning through a novel word learning experiment with adults, for different 'flavors' of modals: epistemic (knowledge-based) versus teleological (goal-based), and comparing novel modals with actual English modals. We find that when learning possibility modals, adult learners behave as expected: they accept novel modals in necessity situations, both in epistemic and teleological contexts, but less often after they've learned a pragmatically more appropriate necessity modal. However, when learning necessity modals, participants manage to learn the right force (i.e., reject them in possibility situations) for epistemic scenarios only; with teleological scenarios, they accept them in possibility situations. We propose that an overlap in modal flavor explains their behavior, specifically, the competition with an ability interpretation in teleological but not epistemic scenarios, which could also contribute to children's difficulty with necessity modals reported in the acquisition literature

Three-Year-Olds\u27 Understanding of Desire Reports Is Robust to Conflict

In this paper, we present two experiments with 3-year-olds, exploring their interpretation of sentences about desires. A mature concept of desire entails that desires may conflict with reality and that different people may have conflicting desires. While previous literature is suggestive, it remains unclear whether young children understand that (a) agents can have counterfactual desires about current states of affairs and (b) agents can have desires that conflict with one\u27s own desires or the desires of others. In this article, we test preschoolers\u27 interpretation of want sentences, in order to better understand their ability to represent conflicting desires, and to interpret sentences reporting these desires. In the first experiment, we use a truth-value judgment task (TVJT) to assess 3-year-olds\u27 understanding of want sentences when the subject of the sentence has a desire that conflicts with reality. In the second experiment, we use a game task to induce desires in the child that conflict with the desires of a competitor, and assess their understanding of sentences describing these desires. In both experiments, we find that 3-year-olds successfully interpret want sentences, suggesting that their ability to represent conflicting desires is adult-like at this age. Given that 3-year-olds generally display difficulty attributing beliefs to others that conflict with reality or with the child\u27s own beliefs, these findings may further cast some doubt on the view that children\u27s persistent difficulty with belief (think) is caused by these kinds of conflicts

Aspects of modality

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2006.Includes bibliographical references (p. 205-214).It is a cross-linguistically robust fact that the same modal auxiliaries come in different flavors: epistemic, deontic, ability, teleological... This fact is neatly captured in a system where each modal has a single lexical entry, where the difference in flavor comes from contextually-provided accessibility relations (cf. Lewis 1973, Kratzer 1981). Equally robust, however, are the phenomena that suggest that epistemics and a subset of deontics are interpreted higher than the remaining flavors (subsumed under the label 'root modals'). The goal of this dissertation is to show that a unified analysis of modal auxiliaries is maintainable, while still providing some principled explanation for the relative ordering of tense, aspect and the various modals in Cinque's (1999) hierarchy, based on evidence in French and Italian. To make sense of the relative scope of modals w.r.t. tense and aspect, I start with the empirical puzzle that aspect interacts differently with the various modal flavors. Perfective aspect on roots in French and Italian yields 'actuality entailments' (cf. Bhatt 1999), that is, an uncancelable inference that the proposition expressed by the complement holds in the actual world, and not merely in some possible world(s).(cont.) I propose that this inference obtains when aspect scopes above the modal, and must therefore take the actual world as its world argument. Because epistemics/deontics are interpreted above aspect, they are immune to the effect. To derive the height problem, I propose to relativize the accessibility relation of a modal to an event, instead of a world: the accessibility relation has a free event variable, which needs to be bound locally, either by aspect (i.e., a quantifier over events), the speech event, or an embedding attitude verb. Further selectional restrictions on the event type each accessibility relation requires limits the possible combinations of event binders and accessibility relations. The resulting binding possibilities reduce the systematic constraints on the range of a modal's interpretations to independently-motivated syntactic assumptions on locality and movement, and explain why the various flavors of the same modal auxiliaries are interpreted at different heights.by Valentine Hacquard.Ph.D

Clause types and speech acts in speech to children

The question of how and when children learn to associate clause type with its canonical function, or speech act, is currently unknown. It is widely observed that declaratives tend to result in assertions, interrogatives in questions, and imperatives in requests. Although such canonical links between clause type and speech acts are principled, they are known to be defeasible. In this corpus study, we investigate how parents talk to their children in the first years of life, and ask how their input might support this mapping, and to what extent it might pose difficulties. We find that the expected link between clause type and speech act is robust in the input, particularly between declaratives and assertions, both of which also occur most frequently. In addition, the non-canonical mappings that do occur are characterized formally, e.g., non-interrogative questions nearly always exhibit rising prosody, and non-imperative requests often contain a modal

Evidence for Altered Cytoskeleton Mobilization Pathway in Splenic Dendritic Cells (DC) from HLA-B27/human b2 microglobulin Transgenic Rats (B27-rats)

Background: Although the association of the MHC class I allele HLA-B27 with Spondyloarthropathy (SpA) has been known for almost 35 years different hypotheses on its relation to disease mechanism still exist in parallel. Several lines of rats transgenic for HLA-B27 and human β2-microglobulin develop an inflammatory disease that strikingly resembles human SpA. It is hypothesized that disease in HLA-B27-transgenic rats arises as a consequence of interaction between antigen-presenting cells expressing high levels of HLA-B27 and peripheral T lymphocytes, and may result from a rupture of tolerance towards gut bacteria. Methods: We used 2D PAGE and iTRAQ to compare the protein expression profile of HLA-B27 dendritic cells (DCs) to that of healthy HLA-B7 expressing and nontransgenic (NTG) rat DCs. MHC II surface expression and apoptotic sensitivity were quantified using flow cytometry. Results: Three protein sets from the proteome analysis were indicative for aberrant cellular processes. First, all proteins involved in protein processing and MHC I assembly were upregulated in B27 DCs, illustrating the higher pressure on the ER due to misfolding of the HLA-B27 heavy chain. Second, all proteins directly influencing actin-dynamics were downregulated. We showed earlier that this not only influences motility, but also plays an important role in deficient immunological synapse formation. Third, the key thiol protease Cathepsin S involved in MHC II synthesis was downregulated, which led us to quantify RT1-B and RT1-D surface expression. Downregulation concerned both CD4+ and CD4- OX62+ HLA-B27 DC subpopulations and maturation enlarged differences in both population bias and expression intensity. Deficient actin dynamics could also contribute to this lower MHC II surface expression. Study of sensitivity to MHC class II-mediated apoptosis by antibody stimulation showed that compared to NTG, both B7 and B27 CD4+ DC were more prone to apoptosis but did not mutually differ. In contrast, overnight culturing resulted in a higher cell death in B27 than in control CD4- DC, even without antibody stimulation. Interestingly, decreased actin dynamics could also be involved in DC apoptosis. Conclusions: We have demonstrated that DCs are a very vulnerable cell type in HLA-B27 rats. Deficient cytoskeletal dynamics could immobilize matured DC in the tissue or induce aberrant migration patterns upon activation. On top of that abnormal intracellular trafficking and membrane organization together with a reduced expression of MHC class II molecules makes them aberrant in T-cell communication by deficient immunological synapse formation. Especially the reduced motility and viability of the tolerigenic CD4- DC could play an important role in initiating a systemic auto-immune response