Locating a weak change using diffuse waves (LOCADIFF) : theoretical approach and inversion procedure

We describe a time-resolved monitoring technique for heterogeneous media. Our approach is based on the spatial variations of the cross-coherence of coda waveforms acquired at fixed positions but at different dates. To locate and characterize a weak change that occurred between successive acquisitions, we use a maximum likelihood approach combined with a diffusive propagation model. We illustrate this technique, called LOCADIFF, with numerical simulations. In several illustrative examples, we show that the change can be located with a precision of a few wavelengths and its effective scattering cross-section can be retrieved. The precision of the method depending on the number of source receiver pairs, time window in the coda, and errors in the propagation model is investigated. Limits of applications of the technique to real-world experiments are discussed.Comment: 11 pages, 14 figures, 1 tabl

REVISITING HUMANITY’S ROOTS: ESTABLISHING AFRICANA PHILOSOPHY’S METAEPISTEMOLOGICAL AND METAPHILOSOPHICAL FOUNDATIONS

This essay underscores the epistemological import of Lewis R. Gordon’s groundbreaking text, An Introduction to Africana Philosophy. The author utilizes a transdisciplinary/creolized method of inquiry to highlight the centrality of Africana philosophy to world history, philosophy, the social sciences, and the history of ideas

Conceptualisation sociologique de la construction sociale du TDAH : médicalisation et pharmaceuticalisation des difficultés scolaires dans un système scolaire potentiellement anomique

Ce mémoire de maitrise constitue une proposition théorique dans le cadre de laquelle je propose une conceptualisation de la construction sociale du trouble déficitaire de l’attention (TDAH) et son traitement par médication psychostimulante, en s’intéressant au processus diagnostique et aux interactions qu’il implique entre les membres de l’écologie scolaire (enseignants, professionnels, élèves, parents, gestionnaires, formateurs), mais aussi entre ces derniers et ceux du domaine médical (médecin généraliste, pédopsychiatre ou psychiatre, pédiatre, psychologue, neurologue). En brossant un portrait exhaustif des connaissances sociales et scientifiques sur ce qu’on nomme communément le TDAH, je présente comment il y a eu redéfinition sociale d’un trouble scolaire en trouble médical, c’est-à-dire comment il y a eu une médicalisation des difficultés scolaires. Cette médicalisation ayant socialement cheminé vers une pharmaceuticalisation de cette non-conformité aux normes scolaires, alors que le traitement par médication psychostimulante est devenu une solution de plus en plus légitime pour plusieurs élèves d’ordre primaire au cours des dernières décennies. Cependant, même si mémoire ne vise pas à nier l’existence d’un tel trouble neurologique, de nombreux facteurs permettent d’observer que des processus sociaux peuvent influencer les taux diagnostiques et les taux de traitement par médication, alors qu’il y a raisons de croire que le Québec est en situation de surdiagnostics et de surprescriptions, principalement chez la population des élèves d’ordre primaire. Suivant cette perspective, ce mémoire propose une conceptualisation sociologique inédite qui pourrait permettre de mieux comprendre comment ces deux phénomènes sont le résultat d’une construction sociale par des processus sociaux. Une conceptualisation qui propose autant d’aborder et d’analyser le TDAH d’un point de vue macrosocial que d’un point de vue microsocial.This master's thesis constitutes a theoretical proposal in which I propose a conceptualization to understand the social construction of ADHD and its treatment with psychostimulant medication, focusing on the diagnostic process and the interactions it involves between members of the school ecology (teachers, professionals, students, parents, managers, trainers), but also between those and those of the medical field (general practitioner, child psychiatrist or psychiatrist, pediatrician, psychologist, neurologist). By providing a comprehensive picture of social and scientific knowledge of what is commonly referred to as ADHD, I present how a school disorder has been socially redefined in a medical disorder, i.e. how academic difficulties have been medicalized. This medicalization has made a social path to pharmaceuticalizing this non-compliance with school standards, while psychostimulant medication treatment has become an increasingly legitimate solution for many primary students in recent decades. However, while memory is not intended to deny the existence of such a neurological disorder, there are many factors that can be observed by social processes that can influence diagnostic rates and rates of medication treatment, while there is reason to believe that Quebec is in a situation of overdiagnosis and overprescription, mainly among the primary student population. From this perspective, this dissertation proposes a new sociological conceptualization that could allow us to better understand how these two phenomena are the result of social construction from social processes. A conceptualization that proposes as much to address and analyze ADHD from a macrosocial point of view as from a microsocial point of view

Algebraic Properties of Valued Constraint Satisfaction Problem

The paper presents an algebraic framework for optimization problems expressible as Valued Constraint Satisfaction Problems. Our results generalize the algebraic framework for the decision version (CSPs) provided by Bulatov et al. [SICOMP 2005]. We introduce the notions of weighted algebras and varieties and use the Galois connection due to Cohen et al. [SICOMP 2013] to link VCSP languages to weighted algebras. We show that the difficulty of VCSP depends only on the weighted variety generated by the associated weighted algebra. Paralleling the results for CSPs we exhibit a reduction to cores and rigid cores which allows us to focus on idempotent weighted varieties. Further, we propose an analogue of the Algebraic CSP Dichotomy Conjecture; prove the hardness direction and verify that it agrees with known results for VCSPs on two-element sets [Cohen et al. 2006], finite-valued VCSPs [Thapper and Zivny 2013] and conservative VCSPs [Kolmogorov and Zivny 2013].Comment: arXiv admin note: text overlap with arXiv:1207.6692 by other author

A combinatorial approach to knot recognition

This is a report on our ongoing research on a combinatorial approach to knot recognition, using coloring of knots by certain algebraic objects called quandles. The aim of the paper is to summarize the mathematical theory of knot coloring in a compact, accessible manner, and to show how to use it for computational purposes. In particular, we address how to determine colorability of a knot, and propose to use SAT solving to search for colorings. The computational complexity of the problem, both in theory and in our implementation, is discussed. In the last part, we explain how coloring can be utilized in knot recognition

Fundamental and realized feeding niche breadths of sexual and asexual stick insects.

The factors contributing to the maintenance of sex over asexuality in natural populations remain unclear. Ecological divergences between sexual and asexual lineages could help to maintain reproductive polymorphisms, at least transiently, but the consequences of asexuality for the evolution of ecological niches are unknown. Here, we investigated how niche breadths change in transitions from sexual reproduction to asexuality. We used host plant ranges as a proxy to compare the realized feeding niche breadths of five independently derived asexual Timema stick insect species and their sexual relatives at both the species and population levels. Asexual species had systematically narrower realized niches than sexual species, though this pattern was not apparent at the population level. To investigate how the narrower realized niches of asexual species arise, we performed feeding experiments to estimate fundamental niche breadths but found no systematic differences between reproductive modes. The narrow realized niches found in asexual species are therefore probably a consequence of biotic interactions such as predation or competition, that constrain realized niche size in asexuals more strongly than in sexuals

The STAR MAPS-based PiXeL detector

The PiXeL detector (PXL) for the Heavy Flavor Tracker (HFT) of the STAR experiment at RHIC is the first application of the state-of-the-art thin Monolithic Active Pixel Sensors (MAPS) technology in a collider environment. Custom built pixel sensors, their readout electronics and the detector mechanical structure are described in detail. Selected detector design aspects and production steps are presented. The detector operations during the three years of data taking (2014-2016) and the overall performance exceeding the design specifications are discussed in the conclusive sections of this paper

Experiences of At-Risk Women in Accessing Breastfeeding Social Support During the Covid-19 Pandemic

Background: With strict public health measures implemented in March 2020 due to the COVID-19 pandemic, many breastfeeding parents, who are within an at-risk population, have experienced limited formal and/or informal breastfeeding social support. In the Canadian context, the experiences of these women is unknown. Research Aim: To explore the experiences of at-risk postpartum breastfeeding women in accessing formal and informal breastfeeding social support during the COVID-19 pandemic. Methods: This was a prospective, longitudinal interpretive description study using mixed methods. Data were gathered using an online survey and one 52–112-min semi-structured interview at 12-weeks postpartum. At-risk breastfeeding participants were those who lack social support and had at least one of the following: age \u3c 25 years; experiencing or had experienced intimate partner violence; or of low income. We sought participants’ experiences of accessing breastfeeding social support during the first few months of the COVID-19 pandemic/lockdown. Seven participants completed the survey and the interview. Results: Participants identified that the COVID-19 pandemic created barriers to accessing formal and informal breastfeeding social support, which stemmed from public health restrictions and difficulties communicating online with families and healthcare providers. Additionally, participants identified that the COVID-19 pandemic/lockdowns facilitated feelings of connectedness, protection, and resiliency. Conclusion: We provide preliminary insight into the experiences of trying to access breastfeeding social support during the COVID-19 pandemic. Future researchers should seek to prioritize improved communication and resources in supporting breastfeeding during COVID-19 and future pandemics/lockdowns

Quantum-assisted quantum compiling

Compiling quantum algorithms for near-term quantum computers (accounting for connectivity and native gate alphabets) is a major challenge that has received significant attention both by industry and academia. Avoiding the exponential overhead of classical simulation of quantum dynamics will allow compilation of larger algorithms, and a strategy for this is to evaluate an algorithm's cost on a quantum computer. To this end, we propose a variational hybrid quantum-classical algorithm called quantum-assisted quantum compiling (QAQC). In QAQC, we use the overlap between a target unitary $U$ and a trainable unitary $V$ as the cost function to be evaluated on the quantum computer. More precisely, to ensure that QAQC scales well with problem size, our cost involves not only the global overlap ${\rm Tr} (V^\dagger U)$ but also the local overlaps with respect to individual qubits. We introduce novel short-depth quantum circuits to quantify the terms in our cost function, and we prove that our cost cannot be efficiently approximated with a classical algorithm under reasonable complexity assumptions. We present both gradient-free and gradient-based approaches to minimizing this cost. As a demonstration of QAQC, we compile various one-qubit gates on IBM's and Rigetti's quantum computers into their respective native gate alphabets. Furthermore, we successfully simulate QAQC up to a problem size of 9 qubits, and these simulations highlight both the scalability of our cost function as well as the noise resilience of QAQC. Future applications of QAQC include algorithm depth compression, black-box compiling, noise mitigation, and benchmarking.Comment: 19 + 10 pages, 14 figures. Added larger scale implementations and proof that cost function is DQC1-har

Effect of Tuned Parameters on a LSA MCQ Answering Model

This paper presents the current state of a work in progress, whose objective is to better understand the effects of factors that significantly influence the performance of Latent Semantic Analysis (LSA). A difficult task, which consists in answering (French) biology Multiple Choice Questions, is used to test the semantic properties of the truncated singular space and to study the relative influence of main parameters. A dedicated software has been designed to fine tune the LSA semantic space for the Multiple Choice Questions task. With optimal parameters, the performances of our simple model are quite surprisingly equal or superior to those of 7th and 8th grades students. This indicates that semantic spaces were quite good despite their low dimensions and the small sizes of training data sets. Besides, we present an original entropy global weighting of answers' terms of each question of the Multiple Choice Questions which was necessary to achieve the model's success.Comment: 9 page