cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Phase boundary and finite temperature crossovers of the quantum Ising model in two dimensions
Creators: name: Strack, P.
name: Jakubczyk, P.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We revisit the two-dimensional quantum Ising model by computing renormalization group flows close to its quantum critical point. The low but finite temperature regime in the vicinity of the quantum critical point is squashed between two distinct non-Gaussian fixed points: the classical fixed point dominated by thermal fluctuations and the quantum critical fixed point dominated by zero-point quantum fluctuations. Truncating an exact flow equation for the effective action we derive a set of renormalization group equations and analyze how the interplay of quantum and thermal fluctuations, both non-Gaussian in nature, influences the shape of the phase boundary and the region in the phase diagram where critical fluctuations occur. The solution of the flow equations makes this interplay transparent: we detect finite temperature crossovers by computing critical exponents and we confirm that the power law describing the finite temperature phase boundary as a function of control parameter is given by the correlation length exponent at zero temperature as predicted in an epsilon-expansion with epsilon=1 by Sachdev, Phys. Rev. B 55, 142 (1997).
description: submitted to Phys. Rev. B Rapid Communications
Using social annotation and web log to enhance search engine
Creators: name: Nguyen, Vu Thanh
Publisher: name: arXiv
Year: 2009
Subjects: subject: Information Retrieval (cs.IR)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences

description: Search services have been developed rapidly in social Internet. It can help web users easily to find their documents. So that, finding a best method search is always an imagine. This paper would like introduce hybrid method of LPageRank algorithm and Social Sim Rank algorithm. LPageRank is the method using link structure to rank priority of page. It doesn't care content of page and content of query. Therefore, we want to use benefit of social annotations to create the latent semantic association between queries and annotations. This model, we use algorithm SocialPageRank and LPageRank to enhance accuracy of search system. To experiment and evaluate the proposed of the new model, we have used this model for Music Machine Website with their web logs.
description: International Journal of Computer Science Issues, IJCSI Volume 6, Issue 2, pp1-6, November 2009
title: The Scale and Scope of Online Retail
Creators: name: Chernoff, Alex
Publisher: name: Bank of Canada
Year: 2018

description: This paper studies the growth of online retail over the period 1999–2012, using confidential firm-product-level data for Canada. The revenue of online retailers is decomposed into the contributions of product scope (the number of product categories) and product scale (average revenue per product category). During this period of rapid online sales growth, product scope dropped dramatically from an average of 59 product categories per firm in 1999 to 5 product categories per firm in 2012. Using data on Amazon.ca's expansion, I find suggestive evidence that this reduction in product scope may have been driven by increased competition in the online retail sector.
description: L’étude examine l’évolution du commerce de détail en ligne sur la période de 1999 à 2012 à l’aide de données confidentielles d’entreprises canadiennes ventilées par produits. Le chiffre d’affaires des détaillants en ligne est décomposé en deux éléments : la gamme, soit le nombre de catégories de produits, et l’ampleur, soit le chiffre d’affaires moyen par catégorie de produits. Sur cette période de croissance rapide des ventes en ligne, la gamme est passée, en moyenne, de 59 à 5 catégories de produits par entreprise. L’analyse de données sur l’expansion d’Amazon.ca donne à penser qu’une concurrence accrue dans le secteur du commerce de détail en ligne pourrait expliquer cette contraction de la gamme de produits.
Violation of the fluctuation-dissipation theorem in time-dependent mesoscopic heat transport
Creators: name: Averin, Dmitri V.
name: Pekola, Jukka P.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We have analyzed the spectral density of fluctuations of the energy flux through a mesoscopic constriction between two equilibrium reservoirs. It is shown that at finite frequencies, the fluctuating energy flux is not related to the thermal conductance of the constriction by the standard fluctuation-dissipation theorem, but contains additional noise. The main physical consequence of this extra noise is that the fluctuations do not vanish at zero temperature together with the vanishing thermal conductance.
description: 5 pages, 1 figure
Interplay of shear and bulk viscosity in generating flow in heavy-ion collisions
Creators: name: Song, Huichao
name: Heinz, Ulrich W
Publisher: name: arXiv
Year: 2009
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We perform viscous hydrodynamic calculations in 2+1 dimensions to investigate the influence of bulk viscosity on the viscous suppression of elliptic flow in non-central heavy-ion collisions at RHIC energies. Bulk and shear viscous effects on the evolution of radial and elliptic flow are studied with different model assumptions for the transport coefficients. We find that the temperature dependence of the relaxation time for the bulk viscous pressure, especially its critical slowing down near the quark-hadron phase transition at T_c, partially offsets effects from the strong growth of the bulk viscosity itself near T_c, and that even small values of the specific shear viscosity eta/s of the fireball matter can be extracted without large uncertainties from poorly controlled bulk viscous effects.
description: 13 pages, 7 figures, 1 table. Submitted to Physical Review C. v2: corrected typos in several entries in Table I
Document Searching System based on Natural Language Query Processing for Vietnam Open Courseware Library
Creators: name: Nguyen, Dang Tuan
name: Luong, Ha Quy-Tinh
Publisher: name: arXiv
Year: 2009
Subjects: subject: Information Retrieval (cs.IR)
subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: The necessary of buiding the searching system being able to support users expressing their searching by natural language queries is very important and opens the researching direction with many potential. It combines the traditional methods of information retrieval and the researching of Question Answering (QA). In this paper, we introduce a searching system built by us for searching courses on the Vietnam OpenCourseWare Program (VOCW). It can be considered as the first tool to be able to perform the user's Vietnamese questions. The experiment results are rather good when we evaluate this system on the precision
description: International Journal of Computer Science Issues, IJCSI Volume 6, Issue 2, pp7-13, November 2009
title: Monograph Reduced Box Price: Managing Human–Deer Conflicts
Creators: name: :none
Publisher: name: Utah State University
Year: 2022

description: Order form for HWI monograph, Methods for Managing Human–Deer Conflicts in Urban, Suburban, and Exurban Areas. This monograph identifies challenges and benefits associated with many human–deer conflict mitigation actions as well as methods to monitor the response of deer populations to management actions. Deer exploit urban, suburban, and exurban areas where human populations provide anthropogenic attractants, either intentionally or inadvertently, which often leads to human–deer conflicts. Mitigating actions have varying degrees of efficacy and may not be effective or accepted in every situation. Wildlife and municipal managers must work together to seek methods to reduce attractants, mitigate conflicts, and perpetuate the conservation of wildlife species that adds to the appreciation of nature in our lives.
Formation of Epitaxial MnBi Layers on (Ga,Mn)As
Creators: name: Adell, J.
name: Adell, M.
name: Ulfat, I.
name: Ilver, L.
name: Sadowski, J.
name: Kanski, J.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The initial growth of MnBi on MnAs terminated (GaMn)As is studied by means of synchrotron based photoelectron spectroscopy. From analysis of surface core level shifts we conclude that a continued epitaxial MnBi layer is formed, in which the MnAs/MnBi interface occurs between As and Bi atomic planes. The well defined 1x2 surface reconstruction of the MnAs surface in preserved for up to 2 ML of MnBi before clear surface degradation occurs.
description: 18 pages, 5 figures
Topological excitations at time vortices in periodically driven systems
Creators: name: Kishony, Gilad
name: Grossman, Ori
name: Lindner, Netanel
name: Rudner, Mark
name: Berg, Erez
Publisher: name: arXiv
Year: 2024
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We consider two-dimensional periodically driven systems of fermions with particle-hole symmetry. Such systems support non-trivial topological phases, including ones that cannot be realized in equilibrium. We show that a space-time defect in the driving Hamiltonian, dubbed a ``time vortex,'' can bind $π$ Majorana modes. A time vortex is a point in space around which the phase lag of the Hamiltonian changes by a multiple of $2π$. We demonstrate this behavior on a periodically driven version of Kitaev's honeycomb spin model, where $\mathbb{Z}_2$ fluxes and time vortices can realize any combination of $0$ and $π$ Majorana modes. We show that a time vortex can be created using Clifford gates, simplifying its realization in near-term quantum simulators.
description: This version matches the published version in npj Quantum Materials. DOI: https://doi.org/10.1038/s41535-025-00745-8
title: Interest Rate and Renewal Risk for Mortgages
Creators: name: Bilyk, Olga
name: Peterson, Brian
name: MacDonald, Cameron
Publisher: name: Bank of Canada
Year: 2018

description: In this note, we explore two types of risk faced by holders of mortgages and home equity lines of credit (HELOCs) in the context of rising interest rates: interest rate risk and renewal risk. We estimate that roughly 53 per cent of outstanding mortgages and HELOCs will face interest rate risk in 2018. However, only about 26 per cent of outstanding mortgages will be renewed in 2018.
description: Dans cette note, nous explorons deux types de risques qui pèsent sur les personnes ayant contracté un prêt hypothécaire ou une ligne de crédit garantie par l’avoir propre foncier dans le contexte actuel marqué par la hausse des taux d’intérêt : le risque de taux d’intérêt et le risque de renouvellement. Nous estimons qu’environ 53 % de l’encours des prêts hypothécaires et des lignes de crédit garanties par l’avoir propre foncier sera exposé au risque de taux d’intérêt en 2018. Cependant, seulement quelque 26 % des prêts hypothécaires seront renouvelés en 2018.
The Adventures of the Rocketeer: Accelerated Motion Under the Influence of Expanding Space
Creators: name: Kwan, Juliana
name: Lewis, Geraint F.
name: James, J. Berian
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It is well known that interstellar travel is bounded by the finite speed of light, but on very large scales any rocketeer would also need to consider the influence of cosmological expansion on their journey. This paper examines accelerated journeys within the framework of Friedmann- Lemaitre-Robertson-Walker universes, illustrating how the duration of a fixed acceleration sharply divides exploration over interstellar and intergalactic distances. Furthermore, we show how the universal expansion increases the difficulty of intergalactic navigation, with small uncertainties in cosmological parameters resulting in significantly large deviations. This paper also shows that, contrary to simplistic ideas, the motion of any rocketeer is indistinguishable from Newtonian gravity if the acceleration is kept small.
description: 9 pages, 7 figures, accepted for publication in PASA
ANALYSIS OF DEEP LEARNING-BASED SUPER-RESOLUTION ON THE CLOUD
Creators: name: Nguyen, Michael
Publisher: name: Zenodo
Year: 2023
Subjects: artificial neural networks
cloud computing
computer vision
deep learning
image quality
super-resolution

description: Digital image processing involves using algorithms to manipulate images for tasks such as image compression, restoration, resizing, filtering, and more. Single-Image Super-Resolution (SISR) is an image processing and computer vision topic that focuses on enhancing an image’s quality by reconstructing a high-resolution (HR) image from its low-resolution (LR) counterpart. Newer Super-Resolution (SR) techniques utilize artificial intelligence (AI) and deep learning, a subset of machine learning. Specifically, they employ large artificial neural networks trained on image degradations, such as those affected by noise and blur, to predict the enhanced image. Neural network architectures, such as convolutional neural networks (CNN), provide an alternative way to interpolate and extract a wide range of image features, including edges, lines, colors, textures, shapes, and patterns for supervised, semi-supervised, and unsupervised SR tasks. Most research evaluates the perceptual quality of an image using traditional image quality metrics, Peak Signal-to-Noise Ratio (PSNR), and Structural Similarity (SSIM). This paper also incorporates three learning-based perceptual metrics, the Blind/Referenceless Image Spatial Quality Evaluator (BRISQUE), Naturalness Image Quality Evaluator (NIQE), and the Learned Perceptual Image Patch Similarity (LPIPS), which take into consideration how images are perceived based on human perception. When considering traditional metrics, the predicted image may not always retain the qualities and details of the original image. However, newer metrics show that deep learning techniques provide visually appealing results and better perceptual quality. A comparative analysis was performed on two deep learning models for SISR: Real-ESRGAN and SwinIR. Both traditional and newer perceptual metrics were considered to determine the model feasibility, in addition to the associated costs of serving the model inference as a cloud application.
Instability of the ACW model, and problems with massive vectors during inflation
Creators: name: Himmetoglu, Burak
name: Contaldi, Carlo R.
name: Peloso, Marco
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We prove that the anisotropic inflationary background of the Ackerman-Carroll-Wise model, characterized by a fixed-norm vector field, is unstable. We found the instability by explicitly solving the linearized equations for the most general set of perturbations around this background, and by noticing that the solutions diverge close to horizon crossing. This happens because one perturbation becomes a ghost at that moment. A simplified computation, with only the perturbations of the vector field included, shows the same instability, clarifying the origin of the problem. We then discuss several other models, with a particular emphasis on the case of a nonminimal coupling to the curvature, in which vector fields are used either to support an anisotropic expansion, or to generate cosmological perturbations on an isotropic background. In many cases, the mass term of the vector needs to have the ``wrong'' sign; we show that, as a consequence, the longitudinal vector mode is a ghost (a field with negative kinetic term, and negative energy; not simply a tachyon). We comment on problems that arise at the quantum level. In particular, the presence of a ghost can be a serious difficulty for the UV completion that such models require in the sub-horizon regime.
description: 22 pages, 4 figures
Gesture Recognition with a Focus on Important Actions by Using a Path Searching Method in Weighted Graph
Creators: name: Tanaka, Kazumoto
Publisher: name: arXiv
Year: 2009
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: This paper proposes a method of gesture recognition with a focus on important actions for distinguishing similar gestures. The method generates a partial action sequence by using optical flow images, expresses the sequence in the eigenspace, and checks the feature vector sequence by applying an optimum path-searching method of weighted graph to focus the important actions. Also presented are the results of an experiment on the recognition of similar sign language words.
description: International Journal of Computer Science Issues, IJCSI Volume 6, Issue 2, pp14-19, November 2009
Multi-hadron states in Lattice QCD spectroscopy
Creators: name: Foley, J.
name: Bulava, J.
name: Juge, K. J.
name: Morningstar, C.
name: Peardon, M.
name: Wong, C. H.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: The ability to reliably measure the energy of an excited hadron in Lattice QCD simulations hinges on the accurate determination of all lower-lying energies in the same symmetry channel. These include not only single-particle energies, but also the energies of multi-hadron states. This talk deals with the determination of multi-hadron energies in Lattice QCD. The group-theoretical derivation of lattice interpolating operators that couple optimally to multi-hadron states is described. We briefly discuss recent algorithmic developments which allow for the efficient implementation of these operators in software, and present numerical results from the Hadron Spectrum Collaboration.
description: 5 pages, 3 figures, talk given at Hadron 2009, Tallahassee, Florida, December 1, 2009
Magnetothermal transport in ultraclean single crystals of Kitaev magnet $α$-RuCl$_3$
Creators: name: Xing, Y.
name: Namba, R.
name: Imamura, K.
name: Ishihara, K.
name: Suetsugu, S.
name: Asaba, T.
name: Hashimoto, K.
name: Shibauchi, T.
name: Matsuda, Y.
name: Kasahara, Y.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The layered honeycomb magnet $α$-RuCl$_3$ has emerged as a promising candidate for realizing a Kitaev quantum spin liquid. Previous studies have reported oscillation-like anomalies in the longitudinal thermal conductivity and half-integer quantized thermal Hall conductivity above the antiferromagnetic critical field $H_c$, generating significant interest. However, the origins of these phenomena remain contentious due to strong sample dependence. Here we re-examine the magnetothermal transport properties using recently available ultra-pure $α$-RuCl$_3$ single crystals to further elucidate potential signatures of the spin liquid state. Our findings reveal that while anomalies in thermal conductivity above $H_c$ persist even in ultraclean crystals, their magnitude is significantly attenuated, contrary to the quantum oscillations hypothesis. This suggests that the anomalies are likely attributable to localized stacking faults inadvertently introduced during magnetothermal transport measurements. The thermal Hall conductivity exhibits a half-quantized plateau, albeit with a narrower width than previously reported. This width reduction can be understood through two distinct mechanisms: sample-dependent magnetic critical fields that influence the lower boundary of the plateau region, and the decoupling between chiral Majorana edge currents and phononic thermal transport that determines the upper boundary. These results indicate that structural imperfections exert a substantial influence on both the oscillation-like anomalies and quantization effects observed in magnetothermal transport measurements of $α$-RuCl$_3$.
description: 7 pages, 4 figures
“Higher” education : a mixed methods exploration of ADHD, cannabis use, and postsecondary academic success
Creators: name: Sharma, Ramona
Publisher: name: University of British Columbia
Year: 2024

description: Problem: Postsecondary students with ADHD are more likely to experience diminished academic self-concept (ASC) and achievement. Some adults with ADHD report using cannabis to alleviate ADHD-related challenges and allow for greater academic and psychosocial functioning. We thus conducted an exploratory, mixed methods study on the numerical and perceived relationships between ADHD, cannabis use, and academic success. Method: We collected data from 586 Canadian postsecondary students with and without ADHD and aged 19+ using an anonymous online survey on Reddit and Facebook. Participants answered questions surrounding their ASC, cumulative GPA (cGPA), major-specific GPA (mGPA), dropped and failed courses, and dropped and failed terms. We also asked a subsample of 180 cannabis users with ADHD open-ended questions about their cannabis use experiences with respect to their ADHD and postsecondary functioning. Quantitative Findings: Analysis of Variance and negative binomial regression procedures indicated cannabis use to be associated with enhanced academic success among ADHD students. Specifically, among non-ADHD students, cannabis users had significantly lower cGPA and mGPA, more dropped courses and more dropped and failed terms per year; however, among ADHD students, cannabis users had higher ASC, and no significant differences in cGPA, mGPA, dropped courses, or dropped or failed terms compared to non-users. Qualitative Findings: Qualitative themes were captured via content analysis. Many students had intentionally used cannabis to manage ADHD challenges and assist with schoolwork by enhancing ASC, creativity, executive functions such as focus, task initiation, and flexible thinking, as well as by reducing hyperactivity-impulsivity, coping with mental health, enhancing sleep and relaxation, enhancing interpersonal relations, and alleviating debilitating stimulant medication side effects. Some found undesirable effects, specifically interrelated forgetfulness, tiredness, and amotivation. Conclusions: The results of this study are cross-sectional and do not determine whether cannabis use or preexisting differences between ADHD cannabis users and non-users caused improved academic success. However, findings indicate many ADHD postsecondary students may perceive benefit from cannabis use. Our study thus highlights the need for further research, and warrants researchers, educators, and clinicians to consider cannabis’s emerging role in assisting with postsecondary success and functioning among ADHD students.
2- and 3-Loop Heavy Flavor Corrections to Transversity
Creators: name: Blümlein, J.
name: Klein, S.
name: Tödtli, B.
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We calculate the two- and three-loop massive operator matrix elements (OMEs) contributing to the heavy flavor Wilson coefficients of transversity. We obtain the complete result for the two-loop OMEs and compute the first thirteen Mellin moments at three-loop order. As a by-product of the calculation, the moments N=1 to 13 of the complete two-loop and the $T_F$-part of the three-loop transversity anomalous dimension are obtained.
description: 6 pages, 1 style file, Contr. to the Proc. of DIS 2009
Amicable pairs and aliquot cycles for elliptic curves
Creators: name: Stange, Katherine E.
name: Silverman, Joseph H.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Number Theory (math.NT)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 11G05 (Primary) 11B37, 11G20, 14G25 (Secondary)

description: An amicable pair for an elliptic curve E/Q is a pair of primes (p,q) of good reduction for E satisfying #E(F_p) = q and #E(F_q) = p. In this paper we study elliptic amicable pairs and analogously defined longer elliptic aliquot cycles. We show that there exist elliptic curves with arbitrarily long aliqout cycles, but that CM elliptic curves (with j not 0) have no aliqout cycles of length greater than two. We give conjectural formulas for the frequency of amicable pairs. For CM curves, the derivation of precise conjectural formulas involves a detailed analysis of the values of the Grossencharacter evaluated at a prime ideal P in End(E) having the property that #E(F_P) is prime. This is especially intricate for the family of curves with j = 0.
description: 53 pages
Petrov D vacuum spaces revisited: Identities and Invariant Classification
Creators: name: Edgar, S. Brian
name: Gómez-Lobo, Alfonso García-Parrado
name: Martín-García, José M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: For Petrov D vacuum spaces, two simple identities are rederived and some new identities are obtained, in a manageable form, by a systematic and transparent analysis using the GHP formalism. This gives a complete involutive set of tables for the four GHP derivatives on each of the four GHP spin coefficients and the one Weyl tensor component. It follows directly from these results that the theoretical upper bound on the order of covariant differentiation of the Riemann tensor required for a Karlhede classification of these spaces is reduced to two.
description: Proof about the Karlhede upper bound improved and discussion of case IIIA re-written. Acknowledgments section expanded. To appear in Classical and Quantum Gravity
Generating Primordial Black Holes Via Hilltop-Type Inflation Models
Creators: name: Alabidi, Laila
name: Kohri, Kazunori
Publisher: name: arXiv
Year: 2009
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: It has been shown that black holes would have formed in the early Universe if, on any given scale, the spectral amplitude of the Cosmic Microwave Background (CMB) exceeds 10^(-4). This value is within the bounds allowed by astrophysical phenomena for the small scale spectrum of the CMB, corresponding to scales which exit the horizon at the end of slow-roll inflation. Previous work by Kohri et. al. (2007) showed that for black holes to form from a single field model of inflation, the slope of the potential at the end of inflation must be flatter than it was at horizon exit. In this work we show that a phenomenological Hilltop model of inflation, satisfying the Kohri et. al. criteria, could lead to the production of black holes, if the power of the inflaton self-interaction is less than or equal to 3, with a reasonable number or e-folds. We extend our analysis to the running mass model, and confirm that this model results in the production of black holes, and by using the latest WMAP year 5 bounds on the running of the spectral index, and the black hole constraint we update the results of Leach et. al. (2000) excluding more of parameter space.
description: 8 pages, 7 figures, updated to match the version published in Phys. Rev. D
On the spectroscopy of quantum dots in microcavities
Creators: name: Laussy, F. P.
name: del Valle, E.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: At the occasion of the OECS conference in Madrid, we give a succinct account of some recent predictions in the spectroscopy of a quantum dot in a microcavity that remain to be observed experimentally, sometimes within the reach of the current state of the art.
description: OECS11 Conference proceedings, in editor style. 4 pages, 1 figure. Animations provided separately
Lexicographic Multi-objective Geometric Programming Problems
Creators: name: Ojha, Dr. A. K.
name: Biswal, K. K.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Computational Geometry (cs.CG)
subject: FOS: Computer and information sciences

description: A Geometric programming (GP) is a type of mathematical problem characterized by objective and constraint functions that have a special form. Many methods have been developed to solve large scale engineering design GP problems. In this paper GP technique has been used to solve multi-objective GP problem as a vector optimization problem. The duality theory for lexicographic geometric programming has been developed to solve the problems with posynomial in objectives and constraints.
description: International Journal of Computer Science Issues, IJCSI Volume 6, Issue 2, pp20-24, November 2009
Art, address, and correspondence : variations on pedagogical presence
Creators: name: Baldus, Angela Inez
Publisher: name: University of British Columbia
Year: 2024

description: This dissertation considers pedagogical presence through material and conceptual variations on correspondence. Presented as artistic research the work aims to address the question what happens in art and correspondence that enables pedagogical presence? Permissions are taken (Lucero, 2023) from scholars and artists working in the arts-based methodologies of a/r/tography (Irwin, 2013) and research-creation (Loveless, 2019) and the autobiographical, educational, practices required to do currere (Pinar, 1974) and feminist reflexivity (Wilkinson, 1988). Together their influence permits the use of correspondence as an experimental and conceptual art practice, and a way of doing research in education. The work acknowledges variations on lived experiences, and the descriptions of experiences (Ellison, 1955), that make correspondence art and a pedagogical object to study. The first chapter the author responds to the work of different artists, poets, writers, and activists who have influenced their understanding of pedagogy. The second chapter features letters between the author and eight participants who joined the author in a correspondence art exchange. The third chapter pushes conceptual and abstract ways of thinking about correspondence and shows how the concept of correspondence travels as it is oriented towards different lines of thought (Bal, 2002). Preluding chapter three the author claims that art is indefinite. Sharing this belief before expanding the notion of correspondence suggests that what comes before and after this part of the dissertation is aware of and interested in its artistic engagements and qualities. The last chapter presents conversations held with participants during a Twitch livestream as evidence of how correspondence might be sustained through different materials. The paper concludes with final thoughts about where this work can go, how, and why it should continue. Pedagogical presence emerges through many variations on correspondence. The dissertation acknowledges the tension between individual experience and collective thinking that happens across different kinds of distance – created through time and difference. The author suggests that correspondences can help enable pedagogical presence which in many ways encourages reflection on our experiences alone and in community. These practices might be considered a kind of study rooted in a desire to live more ethically responsive and curious.
Time limits as potential source of gender bias
Creators: name: Stoevenbelt, Andrea
name: Schwabe, Inga
name: Wicherts, Jelte
Publisher: name: Open Science Framework
Year: 2022
Subjects: subject: Social and Behavioral Sciences

description: This preregistration contains details on the data and models that we employ to investigate whether 1) the relationship between missingness propensity and mathematics ability; 2) whether women perform worse than men do under time limits; and 3) whether women are at a double disadvantage on speeded tests under stereotype threat conditions.
Intrinsic and dislocation induced elastic behavior of solid helium
Creators: name: Day, James
name: Syshchenko, Oleksandr
name: Beamish, John
Publisher: name: arXiv
Year: 2009
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Recent experiments showed that the shear modulus of solid 4He stiffens in the same temperature range (below 200 mK) where mass decoupling and supersolidity have been inferred from torsional oscillator measurements. The two phenomena are clearly related and crystal defects, particularly dislocations, appear to be involved in both. We have studied the effects of annealing and the effects of applying large stresses on the elastic properties of solid 4He, using both acoustic resonances and direct low-frequency and low-amplitude measurements of the shear modulus. Both annealing and stressing affect the shear modulus, as expected if dislocations are responsible. However, it is the high temperature modulus which is affected; the low temperature behavior is unchanged and appears to reflect the intrinsic modulus of solid helium. We interpret this behavior in terms of dislocations which are pinned by isotopic 3He impurities at low temperatures and so have no effect on the shear modulus. At higher temperatures they become mobile and weaken the solid. Stressing the crystal at low temperatures appears to introduce new defects or additional pinning sites for the dislocation network but these effects can be reversed by heating the crystal above 500 mK. This is in contrast to dislocations produced during crystal growth, which are only annealed at temperatures close to melting.
Amoeba: An AGN Model of Optical Emissions Beyond steady-state Accretion discs
Creators: name: Best, Henry
name: O'Dowd, Matthew
name: Fagin, Joshua
name: Chan, James H. H.
name: Ierace, Bridget
Publisher: name: arXiv
Year: 2024
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Active Galactic Nuclei (AGN) are objects located in the heart of galaxies which emit powerful and complex radiation across the electromagnetic spectrum. Understanding AGN has become a topic of interest due to their importance in galactic evolution and their ability to act as a probe to the distant Universe. Within the next few years, wide-field surveys such as the Legacy Survey of Space and Time (LSST) at the Rubin Vera Observatory are expected to increase the number of known AGN to $\mathcal{O} (10^{7})$ and the number of strongly lensed AGN to $\mathcal{O} (10^{4})$. In this paper we introduce \texttt{Amoeba}: an AGN Model of Optical Emission Beyond steady-state Accretion discs. The goal of \texttt{Amoeba} is to provide a modular and flexible modelling environment for AGN, in which all components can interact with each other. Through this work we describe the framework for major AGN components to vary self-consistently and keep flux distributions to connect these components to spatial dependent processes. We model properties beyond traditional single-component models, such as the reverberation of the corona's bending power law power spectrum through the accretion disc and broad line region (BLR). We simulate obscuration by the dusty torus and differential magnification of the disc and BLR due to microlensing. These features are joined together to create some of the most realistic light curve simulations to date. \texttt{Amoeba} takes a step forward in AGN modelling by joining the accretion disc, BLR, torus, intrinsic signal, and microlensing into a coherent model.
Ultracold molecules from ultracold atoms: a case study with the KRb molecule
Creators: name: Julienne, Paul S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Ultracold collisions of cold atoms or molecules make the bound states of the collision complex formed from the two colliding species accessible for control and manipulation of the cold species or the complex. Such resonances are best treated by a resonant scattering theory, which in the ultracold domain can take advantage of the properties of the long-range potential and the methods of multichannel quantum defect theory. Coupled channels calculations on the threshold scattering states and bound states of the 40K87Rb molecule illustrate the ideas and methodology of quantum defect theory using the long-range potential and also demonstrate the spin properties of the bound states throughout the spectrum.
description: Paper for the Discussions of the Faraday Society, Number 142: Cold and Ultracold Molecules, April 15-17, 2009, Durham University, UK;Version 2 is accepted for publication with some typographical corrections and minor text and figure revisions for clarification
Massive Protoplanetary Disks in Orion Beyond the Trapezium Cluster
Creators: name: Mann, Rita K.
name: Williams, Jonathan P.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We present Submillimeter Array observations of the 880 micron continuum emission from three circumstellar disks around young stars in Orion that lie several arcminutes (> 1-pc) north of the Trapezium cluster. Two of the three disks are in the binary system 253-1536. Silhouette disks 216-0939 and 253-1536a are found to be more massive than any previously observed Orion disks, with dust masses derived from their submillimeter emission of 0.045 Msun and 0.066 Msun, respectively. The existence of these massive disks reveals the disk mass distribution in Orion does extend to high masses, and that the truncation observed in the central Trapezium cluster is a result of photoevaporation due to the proximity of O-stars. 253-1536b has a disk mass of 0.018 Msun, making the 253-1536 system the first optical binary in which each protoplanetary disk is massive enough to potentially form Solar systems.
description: ApJL in press
The Geometry of Concepts: Sparse Autoencoder Feature Structure
Creators: name: Li, Yuxiao
name: Michaud, Eric J.
name: Baek, David D.
name: Engels, Joshua
name: Sun, Xiaoqing
name: Tegmark, Max
Publisher: name: arXiv
Year: 2024
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Biological sciences
subject: FOS: Computer and information sciences

description: Sparse autoencoders have recently produced dictionaries of high-dimensional vectors corresponding to the universe of concepts represented by large language models. We find that this concept universe has interesting structure at three levels: 1) The "atomic" small-scale structure contains "crystals" whose faces are parallelograms or trapezoids, generalizing well-known examples such as (man-woman-king-queen). We find that the quality of such parallelograms and associated function vectors improves greatly when projecting out global distractor directions such as word length, which is efficiently done with linear discriminant analysis. 2) The "brain" intermediate-scale structure has significant spatial modularity; for example, math and code features form a "lobe" akin to functional lobes seen in neural fMRI images. We quantify the spatial locality of these lobes with multiple metrics and find that clusters of co-occurring features, at coarse enough scale, also cluster together spatially far more than one would expect if feature geometry were random. 3) The "galaxy" scale large-scale structure of the feature point cloud is not isotropic, but instead has a power law of eigenvalues with steepest slope in middle layers. We also quantify how the clustering entropy depends on the layer.
description: 16 pages, 12 figures
The relation between the most-massive star and its parental star cluster mass
Creators: name: Weidner, C.
name: Kroupa, P.
name: Bonnell, I.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present a thorough literature study of the most-massive star, m_max, in several young star clusters in order to assess whether or not star clusters are populated from the stellar initial mass function (IMF) by random sampling over the mass range 0.01 < m < 150 M_sol without being constrained by the cluster mass, M_ecl. The data reveal a partition of the sample into lowest mass objects (M_ecl < 10^2 M_sol), moderate mass clusters (10^2 M_sol < M_ecl < 10^3 M_sol) and rich clusters above 10^3 M_sol. Additionally, there is a plateau of a constant maximal star mass (m_max ~ 25 M_sol) for clusters with masses between 10^3 M_sol and 4 10^3 M_sol. Statistical tests of this data set reveal that the hypothesis of random sampling from the IMF between 0.01 and 150 M_sol is highly unlikely for star clusters more massive than 10^2 M_sol with a probability of p ~ 2 10^-7 for the objects with M_ecl between 10^2 M_sol and 10^3 M_sol and p ~ 3 10^-9 for the more massive star clusters. Also, the spread of m_max values at a given M_ecl is smaller than expected from random sampling. We suggest that the basic physical process able to explain this dependence of stellar inventory of a star cluster on its mass may be the interplay between stellar feedback and the binding energy of the cluster-forming molecular cloud core. Given these results, it would follow that an integrated galactic initial mass function (IGIMF) sampled from such clusters would automatically be steeper in comparison to the IMF within individual star clusters.
description: 26 pages, 13 figures, 3 tables, accepted for publication in MNRAS
Formation of Random Dark Envelope Solitons from Incoherent Waves
Creators: name: Tong, Wei
name: Wu, Mingzhong
name: Carr, Lincoln D.
name: Kalinikos, Boris A.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: This letter reports experimental results on a new type of soliton: the random temporal dark soliton. One excites an incoherent large-amplitude propagating spin-wave packet in a ferromagnetic film strip with a repulsive, instantaneous nonlinearity. One then observes the random formation of dark solitons from this wave packet. The solitons appear randomly in time and in position relative to the entire wave packet. They can be gray or black. For wide and/or very strong spin-wave packets, one also observes multiple dark solitons. In spite of the randomness of the initial wave packets and the random formation processes, the solitons show signatures that are found for conventional coherent dark solitons.
description: 10 pages, 4 figures, double-spaced preprint format
Superconductivity and Field-Induced Magnetism in SrFe_1.75Co_0.25As_2
Creators: name: Khasanov, R.
name: Maisuradze, A.
name: Maeter, H.
name: Kwadrin, A.
name: Luetkens, H.
name: Amato, A.
name: Schnelle, W.
name: Rosner, H.
name: Leithe-Jasper, A.
name: Klauss, H. -H.
Publisher: name: arXiv
Year: 2009
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Using muon-spin rotation, we studied the in-plane (λ_ab) and the out of plane (λ_c) magnetic field penetration depth in SrFe_1.75Co_0.25As_2 (T_c=13.3 K). Both λ_ab(T) and λ_c(T) are consistent with the presence of two superconducting gaps with the gap to T_c ratios 2Δ/k_BT_c=7.2 and 2.7. The penetration depth anisotropy γ_λ=λ_c/λ_ab increases from γ_λ=2.1 at T_c to 2.7 at 1.6 K. The mean internal field in the superconducting state increases with decreasing temperature, just opposite to the diamagnetic response seen in magnetization experiments. This unusual behavior suggests that the external field induces a magnetic order which is maintained throughout the whole sample volume.
description: 4 pages, 3 figures
Investigating evolutionary conservation and population specificity of DNA methylation
Creators: name: Dong, Zheng
Publisher: name: University of British Columbia
Year: 2024

description: Evolutionary processes shape molecular and phenotypic variation and preserve functionally important DNA sequences. Although genomic divergence and conservation have been investigated extensively, epigenomic divergence and conservation remain largely unclear. Particularly, there have been no systematic studies regarding evolutionarily conserved DNA methylation (DNAm), and the population specificity of DNAm has been examined for only ~3.0% of genomic CpGs. To systematically characterize evolutionarily conserved DNAm, I identified methylation-conserved CpGs (MCCs) across great apes and examined their genetic basis, quantitative nature, and potential functional relevance using 202 DNAm array data sets as well as 6 matched genotype and 13 matched transcription data sets. Specifically, I identified 11,500 MCCs genome-wide and separately demonstrated positive relations of CpG methylation conservation with sequence conservation of CpG and DNAm quantitative trait loci. I also determined stable DNAm patterns of MCCs across human individuals and across demographic and environmental factors, tissue types, and noncancer diseases; nonetheless, they varied significantly in multiple cancers. Functional enrichment analysis showed that genes whose expression was associated with MCCs were enriched for cell development and canonical cancer pathways. Furthermore, to obtain a comprehensive picture of population-specific DNAm, I quantified DNAm using whole-genome bisulfite sequencing data from 65 lymphoblastoid B-cell line samples, and analyzed these data together with matched genotype data. Specifically, 101 population-specific co-methylated regions were identified between individuals of European and African ancestry, which were located in genes related to metabolism and infection. Of these, 91 were uniquely identified here compared to previous array-based studies. I also showed that genetic variation played an important role in the population specificity of DNAm and provided a genetic basis for its expansion to East Asian populations and other blood-based samples. Finally, I investigated the impact of the new complete telomere-to-telomere human genome assembly, T2T-CHM13, on genome-wide DNAm analysis, and suggested that it has significant benefits for analyses by including previously unobserved CpGs in short-read sequencing data and by reducing the potential impact of probe cross-reactivity and mismatch for DNAm arrays. Overall, these analyses contributed to the identification and characterization of epigenomic divergence and conservation, especially in terms of their genetic basis and potential functional relevance.