BU Open Access Articleshttps://hdl.handle.net/2144/168442021-08-04T10:45:55Z2021-08-04T10:45:55ZComplex inferiorities: the poetics of the weaker voice in Latin literatureUden, Jameshttps://hdl.handle.net/2144/428312021-08-04T04:04:46Z2020-01-01T00:00:00ZComplex inferiorities: the poetics of the weaker voice in Latin literature
Uden, James
2020-01-01T00:00:00ZDesign, food and human connection: a research project with the intent of understanding the parallels between chefs and designersRock, Nicholashttps://hdl.handle.net/2144/428302021-08-04T04:04:45ZDesign, food and human connection: a research project with the intent of understanding the parallels between chefs and designers
Rock, Nicholas
Mapping the garden of forking paths: the case of social & financial performanceKing, AndrewBerchicci, Lucahttps://hdl.handle.net/2144/428292021-08-04T04:04:44ZMapping the garden of forking paths: the case of social & financial performance
King, Andrew; Berchicci, Luca
Many scholars lament the difficulty of learning from individual research reports. Replication is often prescribed as a salve, but few replications are conducted and even fewer allow the formation of a coherent understanding. In this article, we propose a complement to replication that emphasizes the mapping of epistemic uncertainties. We demonstrate our approach by exploring the results of six related studies on the link between social and financial performance. We show that our method allows synthesis of seemingly conflicting findings, and we propose that it should be used proactively, prior to replication, to speed the growth of knowledge.
On dynamical systems perturbed by a null-recurrent fast motion: the continuous coefficient case with independent driving noisesPajor-Gyulai, ZsoltSalins, Michaelhttps://hdl.handle.net/2144/428282021-08-04T04:04:42Z2016-09-01T00:00:00ZOn dynamical systems perturbed by a null-recurrent fast motion: the continuous coefficient case with independent driving noises
Pajor-Gyulai, Zsolt; Salins, Michael
An ordinary differential equation perturbed by a null-recurrent diffusion will be considered in the case where the averaging type perturbation is strong only when a fast motion is close to the origin. The normal deviations of these solutions from the averaged motion are studied, and a central limit type theorem is proved. The limit process satisfies a linear equation driven by a Brownian motion time changed by the local time of the fast motion.
2016-09-01T00:00:00ZAn improved uniqueness result for a system of stochastic differential equations related to the stochastic wave equationMueller, C.Neuman, E.Salins, M.Truong, G.https://hdl.handle.net/2144/428272021-08-04T04:04:41Z2019-01-01T00:00:00ZAn improved uniqueness result for a system of stochastic differential equations related to the stochastic wave equation
Mueller, C.; Neuman, E.; Salins, M.; Truong, G.
We improve on the strong uniqueness results of [GLM+17], which deal with the following system of SDE. dX_t = Y_t dt dY_t = |X_t|^𝛂 dB_t and X_0 = x_0, Y_0 = y_0. For (x_0, y_0) ≠ (0, 0), we show that short-time uniqueness holds for 𝛂 > -1/2.
2019-01-01T00:00:00ZExistence and uniqueness for the mild solution of the stochastic heat equation with non-Lipschitz drift on an unbounded spatial domainSalins, M.https://hdl.handle.net/2144/428262021-08-04T04:04:30Z2020-01-01T00:00:00ZExistence and uniqueness for the mild solution of the stochastic heat equation with non-Lipschitz drift on an unbounded spatial domain
Salins, M.
We prove the existence and uniqueness of the mild solution for a nonlinear stochastic heat equation defined on an unbounded spatial domain. The nonlinearity is not assumed to be globally, or even locally, Lipschitz continuous. Instead the nonlinearity is assumed to satisfy a one-sided Lipschitz condition. First, a strengthened version of the Kolmogorov continuity theorem is introduced to prove that the stochastic convolutions of the fundamental solution of the heat equation and a spatially homogeneous noise grow no faster than polynomially. Second, a deterministic mapping that maps the stochastic convolution to the solution of the stochastic heat equation is proven to be Lipschitz continuous on polynomially weighted spaces of continuous functions. These two ingredients enable the formulation of a Picard iteration scheme to prove the existence and uniqueness of the mild solution.
2020-01-01T00:00:00ZModerate deviations for systems of slow-fast stochastic reaction-diffusion equationsGasteratos, IoannisSalins, MichaelSpiliopoulos, Konstantinoshttps://hdl.handle.net/2144/428252021-08-03T04:00:15Z2020-01-01T00:00:00ZModerate deviations for systems of slow-fast stochastic reaction-diffusion equations
Gasteratos, Ioannis; Salins, Michael; Spiliopoulos, Konstantinos
The goal of this paper is to study the Moderate Deviation Principle (MDP) for a system of stochastic reaction-diffusion equations with a time-scale separation in slow and fast components and small noise in the slow component. Based on weak convergence methods in infinite dimensions and related stochastic control arguments, we obtain an exact form for the moderate deviations rate function in different regimes as the small noise and time-scale separation parameters vanish. Many issues that come up due to the infinite dimensionality of the problem are completely absent in their finite-dimensional counterpart. In comparison to corresponding Large Deviation Principles, the moderate deviation scaling necessitates a more delicate approach to establishing tightness and properly identifying the limiting behavior of the underlying controlled problem. The latter involves regularity properties of a solution of an associated elliptic Kolmogorov equation on Hilbert space along with a finite-dimensional approximation argument.
2020-01-01T00:00:00ZSystems of small-noise stochastic reaction-diffusion equations satisfy a large deviations principle that is uniform over all initial dataSalins, Michaelhttps://hdl.handle.net/2144/428242021-08-03T04:00:12ZSystems of small-noise stochastic reaction-diffusion equations satisfy a large deviations principle that is uniform over all initial data
Salins, Michael
This paper proves three uniform large deviations results for a system of stochastic reaction--diffusion equations exposed to small multiplicative noise. If the reaction term can be written as the sum of a decreasing function and a Lipschitz continuous function and the multiplicative noise term is Lipschitz continuous, then the system satisfies a large deviations principle that is uniform over bounded subsets of initial data. Under the stronger assumption that the multiplicative noise term is uniformly bounded, the large deviations principle is uniform over all initial data, not just bounded sets. Alternatively, if the reaction term features super-linear dissipativity, like odd-degree polynomials with negative leading terms do, and the multiplicative noise term is unbounded, but does not grow too quickly, then the large deviations principle is uniform over all initial data.
How we write plaguesUden, Jameshttps://hdl.handle.net/2144/428232021-08-03T04:00:11Z2020-01-01T00:00:00ZHow we write plagues
Uden, James
2020-01-01T00:00:00ZThe margins of satire: Suetonius, satura, and scholarly outsiders in ancient RomeUden, Jameshttps://hdl.handle.net/2144/428222021-08-03T04:00:10Z2020-01-01T00:00:00ZThe margins of satire: Suetonius, satura, and scholarly outsiders in ancient Rome
Uden, James
Scholars have long been interested in Suetonius' De Grammaticis et Rhetoribus for the evidence it preserves of the history of education and philology at Rome. This article focuses on a different aspect of the work: its repeated links with satire. Suetonius' grammatici are presented both as authors and targets of satirical attacks, and fragments of their work preserved in the De Grammaticis et Rhetoribus reveal a wider, sub-elite field of satirical writing occluded in the polished, literary genre of Roman satura. Through analysis of Suetonius' biographical vignettes and related passages in Juvenal's Satire 7, this article sheds light on a vision of grammatici as outsiders who critique Rome—and each other—from the social and literary margins.
2020-01-01T00:00:00ZThe contributions of crosslinguistic influence and individual differences to nonnative speech perceptionChang, CharlesKwon, Sungmihttps://hdl.handle.net/2144/428212021-08-03T04:00:09Z2020-10-31T00:00:00ZThe contributions of crosslinguistic influence and individual differences to nonnative speech perception
Chang, Charles; Kwon, Sungmi
Perception of a nonnative language (L2) is known to be affected by crosslinguistic transfer from a listener's native language (L1), but the relative importance of L1 transfer vis-a-vis individual learner differences remains unclear. This study explored the hypothesis that the nature of L1 transfer changes as learners gain experience with the L2, such that individual differences are more influential at earlier stages of learning and L1 transfer is more influential at later stages of learning. To test this hypothesis, novice L2 learners of Korean from diverse L1 backgrounds were examined in a pretest-posttest design with respect to their perceptual acquisition of novel L2 consonant contrasts (the three-way Korean laryngeal contrast among lenis, fortis, and aspirated plosives) and vowel contrasts (/o/-/ʌ/, /u/-/ɨ/). Whereas pretest performance showed little evidence of L1 effects, posttest performance showed significant L1 transfer. Furthermore, pretest performance did not predict posttest performance. These findings support the view that L1 knowledge influences L2 perception dynamically, according to the amount of L2 knowledge available to learners at that time. That is, both individual differences and L1 knowledge play a role in L2 perception, but to different degrees over the course of L2 development.
2020-10-31T00:00:00ZToward an understanding of heritage prosodyChang, CharlesYao, Yaohttps://hdl.handle.net/2144/428202021-08-03T04:00:06ZToward an understanding of heritage prosody
Chang, Charles; Yao, Yao
In previous work examining heritage language phonology, heritage speakers have often patterned differently from native speakers and late-onset second language (L2) learners with respect to overall accent and segmentals. The current study extended this line of inquiry to suprasegmentals, comparing the properties of lexical tones produced by heritage, native, and L2 speakers of Mandarin living in the U.S. We hypothesized that heritage speakers would approximate native norms for Mandarin tones more closely than L2 speakers, yet diverge from these norms in one or more ways. We further hypothesized that, due to their unique linguistic experience, heritage speakers would sound the most ambiguous in terms of demographic background. Acoustic data showed that heritage speakers approximated native-like production more closely than L2 speakers with respect to the pitch contour of Tone 3, durational shortening in connected speech, and rates of Tone 3 reduction in non-phrase-final contexts, while showing the highest levels of tonal variability among all groups. Perceptual data indicated that heritage speakers’ tones differed from native and L2 speakers’ in terms of both intelligibility and perceived goodness. Consistent with the variability results, heritage speakers were the most difficult group to classify demographically. Taken together, these findings suggest that, with respect to tone, early heritage language experience can, but does not necessarily, result in a phonological advantage over L2 learners. Further, they add support to the view that heritage speakers are language users distinct from both native and L2 speakers.
Inference on conditional quantile processes in partially linear models with applications to the impact of unemployment benefitsQu, ZhongjunYoon, JungmoPerron, Pierrehttps://hdl.handle.net/2144/428192021-08-03T03:59:53Z2021-01-01T00:00:00ZInference on conditional quantile processes in partially linear models with applications to the impact of unemployment benefits
Qu, Zhongjun; Yoon, Jungmo; Perron, Pierre
We propose methods to estimate and conduct inference on conditional quantile processes for models with nonparametric and linear components. The estimation procedure uses local linear or quadratic regressions, with the bandwidth allowed to vary across quantiles to adapt to data sparsity. We establish a Bahadur representation that holds uniformly in the covariate value and the quantile index. Then,we show that the proposed estimator converges weakly to a Gaussian process and develop methods for constructing uniform confidence bands and hypothesis testing. Our results also cover locally partially linear models with boundary points, thereby allowing for Sharp Regression Discontinuity Designs (SRD). This allows us to study the effects of unemployment insurance (UI) benefits extensions using the dataset of Nekoei and Weber (2017) who found a statistically significant effect, though of minor economic importance using an SRD focusing on the average effect. Our model allows heterogeneity with respect to both the covariate and the quantile. We find economically strong significant effects in the tail of the distribution,say the 10% quantile of the outcome variable (e.g., the wage change distribution). Under a rank invariance assumption, this implies that individuals who benefited the most are those who would have experienced substantial wage cuts if there were no benefit extension. Since our setup allows for discrete covariates, we also find positive and statistically significant effects for white-collar and female workers and those with a college education, but not for blue-collar male workers without higher education. Hence, while UI benefits reduce the within-group inequality for some subgroups by covariates, they can be viewed as regressive and enhancing between-group inequality, although they also help to bridge the gender gap.
2021-01-01T00:00:00ZNMR relaxation in the spin-1 Heisenberg chainCapponi, SylvainDupont, MaximeSandvik, Anders W.Sengupta, Pinakihttps://hdl.handle.net/2144/428182021-08-02T04:13:11Z2019-09-09T00:00:00ZNMR relaxation in the spin-1 Heisenberg chain
Capponi, Sylvain; Dupont, Maxime; Sandvik, Anders W.; Sengupta, Pinaki
We consider the isotropic S=1 Heisenberg chain with a finite Haldane gap Δ and use state-of-the-art numerical techniques to investigate its dynamical properties at finite temperature, focusing on the nuclear spin-lattice relaxation rate 1/T1 measured in nuclear magnetic resonance (NMR) experiments, for instance. In particular, we analyze the contributions from modes with momenta close to q≈0 and q≈π as a function of temperature. At high-temperature we observe spin diffusion, while at low-temperature we argue that a simple activated behavior 1/T1∝exp(−Δ/T) can be observed only at temperatures much smaller than the gap Δ.
2019-09-09T00:00:00ZHilbert space fragmentation and Ashkin-Teller criticality in fluctuation coupled Ising modelsPatil, PranaySandvik, Anders W.https://hdl.handle.net/2144/428172021-08-02T04:13:09Z2020-01-31T00:00:00ZHilbert space fragmentation and Ashkin-Teller criticality in fluctuation coupled Ising models
Patil, Pranay; Sandvik, Anders W.
We discuss the effects of exponential fragmentation of the Hilbert space on phase transitions in the context of coupled ferromagnetic Ising models in arbitrary dimension with special emphasis on the one-dimensional case. We show that the dynamics generated by quantum fluctuations is bounded within spatial partitions of the system and weak mixing of these partitions caused by global transverse fields leads to a zero temperature phase with ordering in the local product of both Ising copies but no long-range order in either species. This leads to a natural connection with the Ashkin-Teller universality class for general lattices. We confirm this for the periodic chain using quantum Monte Carlo simulations. We also point out that our treatment provides an explanation for pseudo-first-order behavior seen in the Binder cumulants of the classical frustrated J1−J2 Ising model and the q=4 Potts model in two dimensions.
2020-01-31T00:00:00ZMonte Carlo renormalization flows in the space of relevant and irrelevant operators: application to three-dimensional clock modelsShao, HuiGuo, WenanSandvik, Anders W.https://hdl.handle.net/2144/428162021-08-02T04:13:09Z2020-02-28T00:00:00ZMonte Carlo renormalization flows in the space of relevant and irrelevant operators: application to three-dimensional clock models
Shao, Hui; Guo, Wenan; Sandvik, Anders W.
We study renormalization group flows in a space of observables computed by Monte Carlo simulations. As an example, we consider three-dimensional clock models, i.e., the XY spin model perturbed by a Z_{q} symmetric anisotropy field. For q=4, 5, 6, a scaling function with two relevant arguments describes all stages of the complex renormalization flow at the critical point and in the ordered phase, including the crossover from the U(1) Nambu-Goldstone fixed point to the ultimate Z_{q} symmetry-breaking fixed point. We expect our method to be useful in the context of quantum-critical points with inherent dangerously irrelevant operators that cannot be tuned away microscopically but whose renormalization flows can be analyzed as we do here for the clock models.
2020-02-28T00:00:00ZBose-Einstein condensation of deconfined spinons in two dimensionsIaizzi, AdamScammell, Harley D.Sushkov, Oleg P.Sandvik, Anders W.https://hdl.handle.net/2144/428152021-08-02T04:13:08Z2020-03-11T00:00:00ZBose-Einstein condensation of deconfined spinons in two dimensions
Iaizzi, Adam; Scammell, Harley D.; Sushkov, Oleg P.; Sandvik, Anders W.
The transition between the Néel antiferromagnet and the valence-bond solid state in two dimensions has become a paradigmatic example of deconfined quantum criticality, a non-Landau transition characterized by fractionalized excitations (spinons). We consider an extension of this scenario whereby the deconfined spinons are subject to a magnetic field. The primary purpose is to identify the exotic scenario of a Bose-Einstein condensate of spinons. We employ quantum Monte Carlo simulations of the J−Q model with a magnetic field, and we perform a quantum field theoretic analysis of the magnetic field and temperature dependence of thermodynamic quantities. The combined analysis provides evidence for Bose-Einstein condensation of spinons and also demonstrates an extended temperature regime in which the system is best described as a gas of spinons interacting with an emergent gauge field.
2020-03-11T00:00:00ZScaling and diabatic effects in quantum annealing with a D-Wave deviceWeinberg, PhillipTylutki, MarekRönkkö, Jami M.Westerholm, JanÅström, Jan A.Manninen, PekkaTörmä, PäiviSandvik, Anders W.https://hdl.handle.net/2144/428142021-08-02T04:13:07Z2020-03-06T00:00:00ZScaling and diabatic effects in quantum annealing with a D-Wave device
Weinberg, Phillip; Tylutki, Marek; Rönkkö, Jami M.; Westerholm, Jan; Åström, Jan A.; Manninen, Pekka; Törmä, Päivi; Sandvik, Anders W.
We discuss quantum annealing of the two-dimensional transverse-field Ising model on a D-Wave device, encoded on L×L lattices with L≤32. Analyzing the residual energy and deviation from maximal magnetization in the final classical state, we find an optimal L dependent annealing rate v for which the two quantities are minimized. The results are well described by a phenomenological model with two powers of v and L-dependent prefactors to describe the competing effects of reduced quantum fluctuations (for which we see evidence of the Kibble-Zurek mechanism) and increasing noise impact when v is lowered. The same scaling form also describes results of numerical solutions of a transverse-field Ising model with the spins coupled to noise sources. We explain why the optimal annealing time is much longer than the coherence time of the individual qubits.
2020-03-06T00:00:00ZComment on “Gapless spin liquid ground state of the spin- 12 J1−J2 Heisenberg model on square lattices”Zhao, BowenTakahashi, JunSandvik, Anders W.https://hdl.handle.net/2144/428132021-08-02T04:13:06Z2020-04-09T00:00:00ZComment on “Gapless spin liquid ground state of the spin- 12 J1−J2 Heisenberg model on square lattices”
Zhao, Bowen; Takahashi, Jun; Sandvik, Anders W.
Liu et al. [Phys. Rev. B 98, 241109 (2018)] used Monte Carlo sampling of the physical degrees of freedom of a projected entangled pair state type wave function for the S=1/2 frustrated J1−J2 Heisenberg model on the square lattice and found a nonmagnetic state argued to be a gapless spin liquid when the coupling ratio g=J2/J1 is in the range g∈[0.42,0.6]. Here we show that their definition of the order parameter for another candidate ground state within this coupling window—a spontaneously dimerized state—is problematic. The order parameter as defined will not detect dimer order when lattice symmeties are broken due to open boundaries or asymmetries originating from the calculation itself. Thus, a dimerized phase for some range of g cannot be excluded (and is likely based on several other recent works).
2020-04-09T00:00:00ZExistence of a spectral gap in the Affleck-Kennedy-Lieb-Tasaki model on the hexagonal latticeLemm, MariusSandvik, Anders W.Wang, Linghttps://hdl.handle.net/2144/428122021-08-02T04:13:04Z2020-05-01T00:00:00ZExistence of a spectral gap in the Affleck-Kennedy-Lieb-Tasaki model on the hexagonal lattice
Lemm, Marius; Sandvik, Anders W.; Wang, Ling
The S=1 Affleck-Kennedy-Lieb-Tasaki (AKLT) quantum spin chain was the first rigorous example of an isotropic spin system in the Haldane phase. The conjecture that the S=3/2 AKLT model on the hexagonal lattice is also in a gapped phase has remained open, despite being a fundamental problem of ongoing relevance to condensed-matter physics and quantum information theory. Here we confirm this conjecture by demonstrating the size-independent lower bound Δ>0.006 on the spectral gap of the hexagonal model with periodic boundary conditions in the thermodynamic limit. Our approach consists of two steps combining mathematical physics and high-precision computational physics. We first prove a mathematical finite-size criterion which gives an analytical, size-independent bound on the spectral gap if the gap of a particular cut-out subsystem of 36 spins exceeds a certain threshold value. Then we verify the finite-size criterion numerically by performing state-of-the-art DMRG calculations on the subsystem.
2020-05-01T00:00:00Z