cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Bulk locality from modular flow
Creators: name: Faulkner, Thomas
name: Lewkowycz, Aitor
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the reconstruction of bulk operators in the entanglement wedge in terms of low energy operators localized in the respective boundary region. To leading order in $N$, the dual boundary operators are constructed from the modular flow of single trace operators in the boundary subregion. The appearance of modular evolved boundary operators can be understood due to the equality between bulk and boundary modular flows and explicit formulas for bulk operators can be found with a complete understanding of the action of bulk modular flow, a difficult but in principle solvable task. We also obtain an expression when the bulk operator is located on the Ryu-Takayanagi surface which only depends on the bulk to boundary correlator and does not require the explicit use of bulk modular flow. This expression generalizes the geodesic operator/OPE block dictionary to general states and boundary regions.
description: 36 pages, 2 figures
Universal many-body response of heavy impurities coupled to a Fermi sea
Creators: name: Schmidt, Richard
name: Knap, Michael
name: Ivanov, Dmitri A.
name: You, Jhih-Shih
name: Cetina, Marko
name: Demler, Eugene
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this work we discuss the dynamical response of heavy quantum impurities immersed in a Fermi gas at zero and at finite temperature. Studying both the frequency and the time domain allows one to identify interaction regimes that are characterized by distinct many-body dynamics. From this theoretical study a picture emerges in which impurity dynamics is universal on essentially all time scales, and where the high-frequency few-body response is related to the long-time dynamics of the Anderson orthogonality catastrophe by Tan relations. Our theoretical description relies on different and complementary approaches: functional determinants give an exact numerical solution for time- and frequency-resolved responses, bosonization provides analytical expressions at low temperatures, and the theory of Toeplitz determinants allows one to analytically predict response up to high temperatures. Using these approaches we predict the thermal decoherence rate and prove that within the considered model the fastest rate of long-time decoherence is given by $γ=πk_BT/4$. We show that Feshbach resonances in cold atomic systems give access to new interaction regimes where quantum effects prevail even in the thermal regime of many-body dynamics. The key signature of this phenomenon is a crossover between exponential decay rates of the real-time Ramsey signal. It is shown that the physics of the orthogonality catastrophe is experimentally observable up to temperatures $T/T_F\lesssim 0.2$ where it leaves its fingerprint in a power-law temperature dependence of thermal spectral weight and we review how this phenomenon is related to the physics of heavy ions in liquid $^3$He and the formation of Fermi polarons. The presented results are in excellent agreement with recent experiments on LiK mixtures, and we predict several phenomena that can be tested using currently available experimental technology.
description: 27+16 pages, 21 figures; final version
Finite-size corrections to quantized particle transport in topological charge pumps
Creators: name: Li, Rui
name: Fleischhauer, Michael
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the quantization of adiabatic charge transport in the insulating ground state of finite systems. Topological charge pumps are used in experiments as an indicator of topological order. In the thermodynamic limit the transport can be related to a topological Berry phase and is thus strictly quantized. This is no longer true for finite systems. We derive finite-size corrections to the transport both for non-interacting and interacting systems and relate them to analytic properties of the single- and many-body Berry curvature. We find that they depend on the details of experimental realizations of the pumps. While they can be non-negligible even in large systems, a proper choice of the pumping protocol can suppress these corrections.
Extreme-Scale Block-Structured Adaptive Mesh Refinement
Creators: name: Schornbaum, Florian
name: Rüde, Ulrich
Publisher: name: arXiv
Year: 2017
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: FOS: Computer and information sciences
subject: 68W10, 68W15, 68U20, 65Y05, 65Y20, 76P05

description: In this article, we present a novel approach for block-structured adaptive mesh refinement (AMR) that is suitable for extreme-scale parallelism. All data structures are designed such that the size of the meta data in each distributed processor memory remains bounded independent of the processor number. In all stages of the AMR process, we use only distributed algorithms. No central resources such as a master process or replicated data are employed, so that an unlimited scalability can be achieved. For the dynamic load balancing in particular, we propose to exploit the hierarchical nature of the block-structured domain partitioning by creating a lightweight, temporary copy of the core data structure. This copy acts as a local and fully distributed proxy data structure. It does not contain simulation data, but only provides topological information about the domain partitioning into blocks. Ultimately, this approach enables an inexpensive, local, diffusion-based dynamic load balancing scheme. We demonstrate the excellent performance and the full scalability of our new AMR implementation for two architecturally different petascale supercomputers. Benchmarks on an IBM Blue Gene/Q system with a mesh containing 3.7 trillion unknowns distributed to 458,752 processes confirm the applicability for future extreme-scale parallel machines. The algorithms proposed in this article operate on blocks that result from the domain partitioning. This concept and its realization support the storage of arbitrary data. In consequence, the software framework can be used for different simulation methods, including mesh based and meshless methods. In this article, we demonstrate fluid simulations based on the lattice Boltzmann method.
description: 38 pages, 17 figures, 11 tables
Non-Perturbative Renormalization Group for the Diffusive Epidemic Process
Creators: name: Tarpin, Malo
name: Benitez, Federico
name: Canet, Léonie
name: Wschebor, Nicolás
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We consider the Diffusive Epidemic Process (DEP), a two-species reaction-diffusion process originally proposed to model disease spread within a population. This model exhibits a phase transition from an active epidemic to an absorbing state without sick individuals. Field-theoretic analyses suggest that this transition belongs to the universality class of Directed Percolation with a Conserved quantity (DP-C). However, some exact predictions derived from the symmetries of DP-C seem to be in contradiction with lattice simulations. Here we revisit the field theory of both DP-C and DEP. We discuss in detail the symmetries present in the various formulations of both models, some of which had not been identified previously. We then investigate the DP-C model using the derivative expansion of the non-perturbative renormalization group formalism. We recover previous results for DP-C near its upper critical dimension $d_c=4$, but show how the corresponding fixed point seems to no longer exist below $d \lesssim 3$. Consequences for the DEP universality class are considered.
description: 12 pages, 2 figures, some corrections
Effective equilibrium states in the colored-noise model for active matter I. Pairwise forces in the Fox and unified colored noise approximations
Creators: name: Wittmann, René
name: Maggi, Claudio
name: Sharma, Abhinav
name: Scacchi, Alberto
name: Brader, Joseph M.
name: Marconi, Umberto Marini Bettolo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The equations of motion of active systems can be modeled in terms of Ornstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should be approximated to yield a Markovian picture for the dynamics and a simplified steady-state condition. We perform a comparative study of the Unified Colored Noise Approximation (UCNA) and the approximation scheme by Fox recently employed within this context. We review the approximations necessary to define effective interaction potentials in the low-density limit and study the conditions for which these represent the behavior observed in two-body simulations for the OUPs model and Active Brownian particles. The demonstrated limitations of the theory for potentials with a negative slope or curvature can be qualitatively corrected by a new empirical modification. In general, we find that in the presence of translational white noise the Fox approach is more accurate. Finally, we examine an alternative way to define a force-balance condition in the limit of small activity.
Contextuality in Canonical Systems of Random Variables
Creators: name: Dzhafarov, Ehtibar N.
name: Cervantes, Víctor H.
name: Kujala, Janne V.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 81P13, 81Q99, 60A99

description: Random variables representing measurements, broadly understood to include any responses to any inputs, form a system in which each of them is uniquely identified by its content (that which it measures) and its context (the conditions under which it is recorded). Two random variables are jointly distributed if and only if they share a context. In a canonical representation of a system, all random variables are binary, and every content-sharing pair of random variables has a unique maximal coupling (the joint distribution imposed on them so that they coincide with maximal possible probability). The system is contextual if these maximal couplings are incompatible with the joint distributions of the context-sharing random variables. We propose to represent any system of measurements in a canonical form and to consider the system contextual if and only if its canonical representation is contextual. As an illustration, we establish a criterion for contextuality of the canonical system consisting of all dichotomizations of a single pair of content-sharing categorical random variables.
description: 12 pages of main text + 8 pages of supplementary text with proofs (version 4 is a minor revision). To be published in Philosophical Transactions of the Royal Society A
Support Theorems and an Injectivity Result for Integral Moments of a Symmetric m-Tensor Field
Creators: name: Abhishek, Anuj
name: Mishra, Rohit Kumar
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: In this work, we show an injectivity result and support theorems for integral moments of a m-tensor field on a simple, real analytic, Riemannian manifold. Integral moments of m-tensor field were first introduced by Sharafutdinov. At first we generalize a Helgason type support theorem proven by Krishnan and Stefanov in "A support theorem for the geodesic ray transform of symmetric tensor fields", Inverse Problems and Imaging, 3(3):453-464,2009. We use this extended result along with the first m+1-integral moments of a m-tensor field to prove the aforementioned results.
title: Impact of pre-OP independence in patients with limited brain metastases on long-term survival
Creators: name: Bleckmann, Annalen
name: Kirchner, Benjamin
name: Nietert, Manuel Manfred
name: Peeck, Micha
name: Balkenhol, Marko
name: Egert, Daniela
name: Rohde, T. Veit
name: Beissbarth, Tim
name: Pukrop, Tobias
Publisher: name: University of Muenster, Institutional Repository MIAMI
Year: 2023
Subjects: subject: 610 Medicine and health

description: Background: Brain metastasis represents a major complication with a significantly shorter overall survival of many oncological diseases, in particular of lung cancer, breast cancer and malignant melanoma patients. However, despite the poor prognosis, sometimes clinical decision-making, between on the one hand not to harm the patient and on the other hand not withholding a potential therapeutic option, is very challenging. Thus the aim of this retrospective study was to compare various scores, including scores for activities of daily living (ADL) before resection of brain metastases and to analyse their impact on survival. Methods: Our single institution retrospective patient cohort (N = 100) with a median age of 63.6 years, which had all undergone resection of one or more brain metastases, was categorized using the original patient files. The cohort includes 52 patients with lung cancer, 27 patients with breast cancer, 8 patients with colorectal carcinoma and 13 patients with kidney cancer. To categorize, we used different score systems which were capable to evaluate the patient in relation to self-sufficiency, activity and self-determination as part of ADL. The retrospective analysis includes the ECOG-Status, Karnofsky-Index, Barthel-Index, ASA-Classification and Katz-Index. Pre-processing and the analysis of the data was implemented using KNIME, where we used the R-plugin nodes to perform the final statistical tests with R. Results: Our analysis reveals that most of the ADL scores we tested are able to give a reliable prediction on overall survival after brain metastasis surgery. The survival rates decrease significantly with a lower score in all tested score systems, with the exception of the ASA-Risk score. In particular, the Katz Index < 6 was identified to have a significant correlation with a lower cancer specific survival (CSS) (HR 3.33, 95%-CI [2.17–5.00]; p-Value = 9.6*10^− 9), which is easy to use and has reproducible measurements. Conclusions: Pre-operative independence assessment by indices of ADL represents a predictor for overall survival after resection of brain metastases. Especially the easily, objectively and rapidly applicable Katz-Score is a very helpful tool to assess the pre-operative status, which could be additionally included in clinical decision making in daily practice.
description: Finanziert über die DEAL-Vereinbarung mit Wiley 2019-2022.
Dimensional Crossover of Charge-Density Wave Correlations in the Cuprates
Creators: name: Caplan, Yosef
name: Orgad, Dror
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Short-range charge-density wave correlations are ubiquitous in underdoped cuprates. They are largely confined to the copper-oxygen planes and typically oscillate out of phase from one unit cell to the next in the c-direction. Recently, it was found that a considerably longer-range charge-density wave order develops in YBCO above a sharply defined crossover magnetic field. This order is more three-dimensional and is in-phase along the c-axis. Here, we show that such behavior is a consequence of the conflicting ordering tendencies induced by the disorder potential and the Coulomb interaction, where the magnetic field acts to tip the scales from the former to the latter. We base our conclusion on analytic large-N analysis and Monte-Carlo simulations of a non-linear sigma model of competing superconducting and charge-density wave orders. Our results are in agreement with the observed phenomenology in the cuprates, and we discuss their implications to other members of this family, which have not been measured yet at high magnetic fields.
description: Published version, including supplementary material
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Gravity test from the combination of redshift-space distortions and galaxy-galaxy lensing at $0.5 < z < 1.2$
Creators: name: de la Torre, S.
name: Jullo, E.
name: Giocoli, C.
name: Pezzotta, A.
name: Bel, J.
name: Granett, B. R.
name: Guzzo, L.
name: Garilli, B.
name: Scodeggio, M.
name: Bolzonella, M.
name: Abbas, U.
name: Adami, C.
name: Bottini, D.
name: Cappi, A.
name: Cucciati, O.
name: Davidzon, I.
name: Franzetti, P.
name: Fritz, A.
name: Iovino, A.
name: Krywult, J.
name: Brun, V. Le
name: Fèvre, O. Le
name: Maccagni, D.
name: Małek, K.
name: Marulli, F.
name: Polletta, M.
name: Pollo, A.
name: Tasca, L. A. M.
name: Tojeiro, R.
name: Vergani, D.
name: Zanichelli, A.
name: Arnouts, S.
name: Branchini, E.
name: Coupon, J.
name: De Lucia, G.
name: Ilbert, O.
name: Moutard, T.
name: Moscardini, L.
name: Peacock, J. A.
name: Metcalf, R. B.
name: Prada, F.
name: Yepes, G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We carry out a joint analysis of redshift-space distortions and galaxy-galaxy lensing, with the aim of measuring the growth rate of structure; this is a key quantity for understanding the nature of gravity on cosmological scales and late-time cosmic acceleration. We make use of the final VIPERS redshift survey dataset, which maps a portion of the Universe at a redshift of $z \simeq 0.8$, and the lensing data from the CFHTLenS survey over the same area of the sky. We build a consistent theoretical model that combines non-linear galaxy biasing and redshift-space distortion models, and confront it with observations. The two probes are combined in a Bayesian maximum likelihood analysis to determine the growth rate of structure at two redshifts $z=0.6$ and $z=0.86$. We obtain measurements of $fσ_8(0.6) = 0.48 \pm 0.12$ and $fσ_8(0.86) = 0.48 \pm 0.10$. The additional galaxy-galaxylensing constraint alleviates galaxy bias and $σ_8$ degeneracies, providing direct measurements of $[f(0.6),σ_8(0.6)] = [0.93 \pm 0.22, 0.52 \pm 0.06]$ and $f(0.86),σ_8(0.86)] = [0.99 \pm 0.19, 0.48 \pm 0.04]$. These measurements are statistically consistent with a Universe where the gravitational interactions can be described by General Relativity, although they are not yet accurate enough to rule out some commonly considered alternatives. Finally, as a complementary test we measure the gravitational slip parameter, $E_G$ , for the first time at $z>0.6$. We find values of $\smash{\overline{E}_G}(0.6) = 0.16 \pm 0.09$ and $\smash{\overline{E}_G}(0.86) = 0.09 \pm 0.07$, when $E_G$ is averaged over scales above $3 h^{-1} \rm{Mpc}$. We find that our $E_G$ measurements exhibit slightly lower values than expected for standard relativistic gravity in a ΛCDM background, although the results are consistent within $1-2σ$.
description: 21 pages, 19 figures, accepted for publication in A&A (referee report received seven months after submission)
Инновационный способ переработки и закладки влажного фуражного зерна на хранение
Creators: name: Симонов Г.А.
name: Никифоров В.Е.
name: Маклахов А.В.
name: Хализова З.Н.
name: Симонов А.Г.
Publisher: name: Эффективное животноводство
Year: 2023
Subjects: способ
фуражное зерно
плющение
консервирование
пневмозагрузка
хранение
method
feed grain
flattening
canning
pneumatic loading
storage

description: В статье рассматривается способ заготовки влажного фуражного зерна с плющением, консервированием и пневмозагрузкой на хранение. Приведена линия с пневмозагрузкой в траншею обработанного консервантом влажного плющеного зерна, которая включает в себя: плющилку, зернометатель ПЗС-100, загрузчик бункерный ЗБ-100-1 РМ. Испытания показали, что производительность пневмотранспорта УПТ-6 на влажном плющеном зерне и соответственно всей технологической линии достигает 4 т/час.
description: The article discusses the method of harvesting wet feed grain with flattening, canning and pneumatic loading for storage. A line with pneumatic loading of wet feed grain treated with preservative into a trench is shown, which includes: a flattener, a CCD-100 grain thrower, a hopper loader ZB-100-1 RM. Tests have shown that the performance of the UPT-6 pneumatic transport on wet flattened grain and, accordingly, the entire production line reaches 4 tons / hour.
On the differentiability of hairs for Zorich maps
Creators: name: Comdühr, Patrick
Publisher: name: arXiv
Year: 2017
Subjects: subject: Dynamical Systems (math.DS)
subject: Complex Variables (math.CV)
subject: FOS: Mathematics
subject: 37F10, 30C65, 30D05

description: Devaney and Krych showed that for the exponential family $λe^z$, where $0
description: 20 pages
Laser Pulse Sharpening with Electromagnetically Induced Transparency in Plasma
Creators: name: Qu, Kenan
name: Fisch, Nathaniel J.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optics (physics.optics)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We propose a laser-controlled plasma shutter technique to generate sharp laser pulses using a process analogous to electromagnetically-induced transparency in atoms. The shutter is controlled by a laser with moderately strong intensity, which induces a transparency window below the cutoff frequency, and hence enables propagation of a low frequency laser pulse. Numerical simulations demonstrate it is possible to generate a sharp pulse wavefront (sub-ps) using two broad pulses in high density plasma. The technique can work in a regime that is not accessible by plasma mirrors when the pulse pedestals are stronger than the ionization intensity.
Exploring the jamming transition over a wide range of critical densities
Creators: name: Ozawa, Misaki
name: Berthier, Ludovic
name: Coslovich, Daniele
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We numerically study the jamming transition of frictionless polydisperse spheres in three dimensions. We use an efficient thermalisation algorithm for the equilibrium hard sphere fluid and generate amorphous jammed packings over a range of critical jamming densities that is about three times broader than in previous studies. This allows us to reexamine a wide range of structural properties characterizing the jamming transition. Both isostaticity and the critical behavior of the pair correlation function hold over the entire range of jamming densities. At intermediate length scales, we find a weak, smooth increase of bond orientational order. By contrast, distorted icosahedral structures grow rapidly with increasing the volume fraction in both fluid and jammed states. Surprisingly, at large scale we observe that denser jammed states show stronger deviations from hyperuniformity, suggesting that the enhanced amorphous ordering inherited from the equilibrium fluid competes with, rather than enhances, hyperuniformity. Finally, finite size fluctuations of the critical jamming density are considerably suppressed in the denser jammed states, indicating an important change in the topography of the potential energy landscape. By considerably stretching the amplitude of the critical "J-line", our work disentangles physical properties at the contact scale that are associated with jamming criticality, from those occurring at larger length scales, which have a different nature.
description: 19 pages, 11 figures, resubmission to SciPost
Converting multilevel nonclassicality into genuine multipartite entanglement
Creators: name: Regula, Bartosz
name: Piani, Marco
name: Cianciaruso, Marco
name: Bromley, Thomas R.
name: Streltsov, Alexander
name: Adesso, Gerardo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Characterizing genuine quantum resources and determining operational rules for their manipulation are crucial steps to appraise possibilities and limitations of quantum technologies. Two such key resources are nonclassicality, manifested as quantum superposition between reference states of a single system, and entanglement, capturing quantum correlations among two or more subsystems. Here we present a general formalism for the conversion of nonclassicality into multipartite entanglement, showing that a faithful reversible transformation between the two resources is always possible within a precise resource-theoretic framework. Specializing to quantum coherence between the levels of a quantum system as an instance of nonclassicality, we introduce explicit protocols for such a mapping. We further show that the conversion relates multilevel coherence and multipartite entanglement not only qualitatively, but also quantitatively, restricting the amount of entanglement achievable in the process and in particular yielding an equality between the two resources when quantified by fidelity-based geometric measures.
description: 10 pages, 1 figure
Generalized Sinkhorn iterations for regularizing inverse problems using optimal mass transport
Creators: name: Karlsson, Johan
name: Ringh, Axel
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 49N45, 90C25, 94A08

description: The optimal mass transport problem gives a geometric framework for optimal allocation, and has recently gained significant interest in application areas such as signal processing, image processing, and computer vision. Even though it can be formulated as a linear programming problem, it is in many cases intractable for large problems due to the vast number of variables. A recent development to address this builds on an approximation with an entropic barrier term and solves the resulting optimization problem using Sinkhorn iterations. In this work we extend this methodology to a class of inverse problems. In particular we show that Sinkhorn-type iterations can be used to compute the proximal operator of the transport problem for large problems. A splitting framework is then used to solve inverse problems where the optimal mass transport cost is used for incorporating a priori information. We illustrate the method on problems in computerized tomography. In particular we consider a limited-angle computerized tomography problem, where a priori information is used to compensate for missing measurements.
description: 25 pages (single column)
Automatic segmentation of trees in dynamic outdoor environments
Creators: name: Tabb, Amy
name: Medeiros, Henry
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Segmentation in dynamic outdoor environments can be difficult when the illumination levels and other aspects of the scene cannot be controlled. Specifically in orchard and vineyard automation contexts, a background material is often used to shield a camera's field of view from other rows of crops. In this paper, we describe a method that uses superpixels to determine low texture regions of the image that correspond to the background material, and then show how this information can be integrated with the color distribution of the image to compute optimal segmentation parameters to segment objects of interest. Quantitative and qualitative experiments demonstrate the suitability of this approach for dynamic outdoor environments, specifically for tree reconstruction and apple flower detection applications.
description: 14 pages
COLA with scale-dependent growth: applications to screened modified gravity models
Creators: name: Winther, Hans A.
name: Koyama, Kazuya
name: Manera, Marc
name: Wright, Bill S.
name: Zhao, Gong-Bo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We present a general parallelized and easy-to-use code to perform numerical simulations of structure formation using the COLA (COmoving Lagrangian Acceleration) method for cosmological models that exhibit scale-dependent growth at the level of first and second order Lagrangian perturbation theory. For modified gravity theories we also include screening using a fast approximate method that covers all the main examples of screening mechanisms in the literature. We test the code by comparing it to full simulations of two popular modified gravity models, namely $f(R)$ gravity and nDGP, and find good agreement in the modified gravity boost-factors relative to $Λ$CDM even when using a fairly small number of COLA time steps.
description: 31 pages, 11 figures. The code can be found at https://github.com/HAWinther/MG-PICOLA-PUBLIC
Steady state of isolated systems versus microcanonical ensemble in cell model of particle creation and annihilation
Creators: name: Gazdzicki, M.
name: Gorenstein, M. I.
name: Fronczak, A.
name: Fronczak, P.
name: Mackowiak-Pawlowska, M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A simple model of particle creation and annihilation in an isolated assembly of particles with conserved energy and fixed volume, the Cell Model, is formulated. With increasing time, particle number distribution, obtained by averaging over many systems, approaches a time-independent, steady state distribution. Dependence of the steady state distribution on creation and annihilation conditional reaction probabilities is studied. The results obtained for the steady state are compared with predictions of statistical mechanics within the microcanonical ensemble. In general, the predictions of both models are different. They agree only if the creation and annihilation conditional probabilities are equal. This condition also results in the detailed balance in the steady state.
description: 25 pages, 5 figures, replaced by the published version
Lorentz invariance violation and simultaneous emission of electromagnetic and gravitational waves
Creators: name: Passos, E.
name: Anacleto, M. A.
name: Brito, F. A.
name: Holanda, O.
name: Souza, G. B.
name: Zarro, C. A. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this work, we compute some phenomenological bounds for the electromagnetic and massive gravitational high-derivative extensions supposing that it is possible to have an astrophysical process that generates simultaneously gravitational and electromagnetic waves. We present Lorentz invariance violating (LIV) higher-order derivative models, following the Myers-Pospelov approach, to electrodynamics and massive gravitational waves. We compute the corrected equation of motion of these models, their dispersion relations and the velocities. The LIV parameters for the gravitational and electromagnetic sectors, $ξ_{g}$ and $ξ_γ$, respectively, were also obtained for three different approaches: luminal photons, time delay of flight and the difference of graviton and photon velocities. These LIV parameters depend on the mass scales where the LIV-terms become relevant, $M$ for the electromagnetic sector and $M_{1}$ for the gravitational one. We obtain, using the values for $M$ and $M_{1}$ found in the literature, that $ξ_{g}\sim10^{-2}$, which is expected to be phenomenologically relevant and $ξ_γ\sim10^{3}$, which cannot be suitable for an effective LIV theory. However, we show that $ξ_γ$ can be interesting in a phenomenological point of view if $M\gg M_{1}$. Finally the relation between the variation of the velocities of the photon and the graviton in relation to the speed of light was calculated and resulted in $Δv_{g}/Δv_γ\lesssim1.82\times 10^{-3}$.
description: Latex, 10 pages, no figures. Version published in PLB
Thickening of viscoelastic flow in a model porous medium
Creators: name: Hemingway, E. J.
name: Clarke, A.
name: Pearson, J. R. A.
name: Fielding, S. M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We study numerically two-dimensional creeping viscoelastic flow past a biperiodic square array of cylinders within the Oldroyd B, FENE-CR and FENE-P constitutive models of dilute polymer solutions. Our results capture the initial mild decrease then dramatic upturn ('thickening') seen experimentally in the drag coefficient as a function of increasing Weissenberg number. By systematically varying the porosity of the flow geometry, we demonstrate two qualitatively different mechanisms underpinning this thickening effect: one that operates in the highly porous case of widely spaced obstacles, and another for more densely packed obstacles, with a crossover between these two mechanisms at intermediate porosities. We also briefly consider 2D creeping viscoelastic flow past a linear array of cylinders confined to a channel, where we find that the flow is steady for all Weissenberg numbers explored.
description: 17 pages, 18 figures; v2 updated to post-referee version: contains two new figures
Fast and scalable Gaussian process modeling with applications to astronomical time series
Creators: name: Foreman-Mackey, Daniel
name: Agol, Eric
name: Ambikasaran, Sivaram
name: Angus, Ruth
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Applications (stat.AP)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: The growing field of large-scale time domain astronomy requires methods for probabilistic data analysis that are computationally tractable, even with large datasets. Gaussian Processes are a popular class of models used for this purpose but, since the computational cost scales, in general, as the cube of the number of data points, their application has been limited to small datasets. In this paper, we present a novel method for Gaussian Process modeling in one-dimension where the computational requirements scale linearly with the size of the dataset. We demonstrate the method by applying it to simulated and real astronomical time series datasets. These demonstrations are examples of probabilistic inference of stellar rotation periods, asteroseismic oscillation spectra, and transiting planet parameters. The method exploits structure in the problem when the covariance function is expressed as a mixture of complex exponentials, without requiring evenly spaced observations or uniform noise. This form of covariance arises naturally when the process is a mixture of stochastically-driven damped harmonic oscillators -- providing a physical motivation for and interpretation of this choice -- but we also demonstrate that it can be a useful effective model in some other cases. We present a mathematical description of the method and compare it to existing scalable Gaussian Process methods. The method is fast and interpretable, with a range of potential applications within astronomical data analysis and beyond. We provide well-tested and documented open-source implementations of this method in C++, Python, and Julia.
description: Updated in response to referee. Submitted to the AAS Journals. Comments (still) welcome. Code available: https://github.com/dfm/celerite
Supplying Dark Energy from Scalar Field Dark Matter
Creators: name: Gogberashvili, Merab
name: Sakharov, Alexander S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.
description: 11 pages, version accepted for publication in the International Journal of Modern Physics D
A Short Introduction to Topological Quantum Computation
Creators: name: Lahtinen, Ville
name: Pachos, Jiannis K.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: This review presents an entry-level introduction to topological quantum computation -- quantum computing with anyons. We introduce anyons at the system-independent level of anyon models and discuss the key concepts of protected fusion spaces and statistical quantum evolutions for encoding and processing quantum information. Both the encoding and the processing are inherently resilient against errors due to their topological nature, thus promising to overcome one of the main obstacles for the realisation of quantum computers. We outline the general steps of topological quantum computation, as well as discuss various challenges faced by it. We also review the literature on condensed matter systems where anyons can emerge. Finally, the appearance of anyons and employing them for quantum computation is demonstrated in the context of a simple microscopic model -- the topological superconducting nanowire -- that describes the low-energy physics of several experimentally relevant settings. This model supports localised Majorana zero modes that are the simplest and the experimentally most tractable types of anyons that are needed to perform topological quantum computation.
description: v4: typos corrected, published version
Galaxy And Mass Assembly (GAMA): 'No Smoking' zone for giant elliptical galaxies?
Creators: name: Khosroshahi, Habib G.
name: Raouf, Mojtaba
name: Miraghaei, Halime
name: Brough, Sarah
name: Croton, Darren J.
name: Driver, Simon
name: Graham, Alister
name: Baldry, Ivan
name: Brown, Michael
name: Prescott, Matt
name: Wang, Lingyu
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study the radio emission of the most massive galaxies in a sample of dynamically relaxed and un-relaxed galaxy groups from Galaxy and Mass Assembly (GAMA). The dynamical state of the group is defined by the stellar dominance of the brightest group galaxy, e.g. the luminosity gap between the two most luminous members, and the offset between the position of the brightest group galaxy and the luminosity centroid of the group. We find that the radio luminosity of the most massive galaxy in the group strongly depends on its environment, such that the brightest group galaxies in dynamically young (evolving) groups are an order of magnitude more luminous in the radio than those with a similar stellar mass but residing in dynamically old (relaxed) groups. This observation has been successfully reproduced by a newly developed semi-analytic model which allows us to explore the various causes of these findings. We find that the fraction of radio loud brightest group galaxies in the observed dynamically young groups is ~2 times that in the dynamically old groups. We discuss the implications of this observational constraint on the central galaxy properties in the context of galaxy mergers and the super-massive blackhole accretion rate.
description: 10 pages, 8 figures. Accepted for publication in ApJ; added references
Probing Surface Quantum Flows in Deformed Pygmy Dipole Modes
Creators: name: Wang, Kai
name: Kortelainen, M.
name: Pei, J. C.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In order to explore the nature of collective modes in weakly bound nuclei, we have investigated deformation effects and surface flow patterns of isovector dipole modes in a shape-coexisting nucleus $^{40}$Mg. The calculations were done in a fully self-consistent continuum finite-amplitude Quasiparticle Random Phase Approximation (QRPA) in a large deformed spatial mesh. An unexpected result of pygmy and giant dipole modes having disproportionate deformation splittings in strength functions was obtained. Furthermore, the transition current densities demonstrate that the long-sought core-halo oscillation in pygmy resonances is collective and compressional, corresponding to the lowest excitation energy and the simplest quantum flow topology. Our calculations show that surface flow patterns become more complicated as excitation energies increase.
description: 5 pages, 4 figures, accepted for Phys.Rev.C (Rapid Comm.)
Supplementary materials for: Lost Loops: 19th century thermosiphon ventilation and its potential for heat recovery in buildings today
Creators: name: Halepaska, Anna
name: Adams, Annmarie
name: Craig, Salmaan
Publisher: name: Zenodo
Year: 2023
Subjects: ventilation
Energy efficiency
Buildings
History of Architecture and Construction

description: We investigate ventilation heat recovery with buoyancy flow, arranging interior spaces in an open thermal loop with heat exchange through partition walls. We draw inspiration from a Victorian-era thermosiphon scheme after finding it in Montreal's former Royal Victoria Hospital and tracing the concept back to the original Centre Block of Canada's Parliament Hill. We corroborate the archival evidence with analog models to visualize how the original hospital's ventilation system worked. We use saline baths to verify how the siphon functioned and digital Schlieren to confirm how the full flow cycle worked with heat recovery. Then, to generalize these observations, we develop a mathematical model showing how heat recovery with buoyancy ventilation can work in simple room arrangements. We define a criterion for stable, unidirectional flow and a heat recovery efficiency limit of 50%. Finally, we validate the mathematical model experimentally, demonstrating stable, one-way flow close to the heat recovery limit.
description: Funding provided by: Canada Foundation for Innovation
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100001805
Award Number: Innovation Fund 2020Funding provided by: Natural Sciences and Engineering Research Council of Canada
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100000038
Award Number: Discovery Grant RGPIN 2022 04490Funding provided by: McGill Sustainability Systems Initiative*
Crossref Funder Registry ID:
Award Number: Clean Tech FundFunding provided by: Summer Undergraduate Research in Engineering, McGill University*
Crossref Funder Registry ID:
Award Number: Funding provided by: Vanier Canada Graduate Scholarship*
Crossref Funder Registry ID:
Award Number: FRN 175756
A Plane of High Velocity Galaxies Across the Local Group
Creators: name: Banik, Indranil
name: Zhao, Hongsheng
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We recently showed that several Local Group (LG) galaxies have much higher radial velocities (RVs) than predicted by a 3D dynamical model of the standard cosmological paradigm. Here, we show that 6 of these 7 galaxies define a thin plane with root mean square thickness of only 101 kpc despite a widest extent of nearly 3 Mpc, much larger than the conventional virial radius of the Milky Way (MW) or M31. This plane passes within ${\sim 70}$ kpc of the MW-M31 barycentre and is oriented so the MW-M31 line is inclined by $16^\circ$ to it. We develop a toy model to constrain the scenario whereby a past MW-M31 flyby in Modified Newtonian Dynamics (MOND) forms tidal dwarf galaxies that settle into the recently discovered planes of satellites around the MW and M31. The scenario is viable only for a particular MW-M31 orbital plane. This roughly coincides with the plane of LG dwarfs with anomalously high RVs. Using a restricted $N$-body simulation of the LG in MOND, we show how the once fast-moving MW and M31 gravitationally slingshot test particles outwards at high speeds. The most distant such particles preferentially lie within the MW-M31 orbital plane, probably because the particles ending up with the highest RVs are those flung out almost parallel to the motion of the perturber. This suggests a dynamical reason for our finding of a similar trend in the real LG, something not easily explained as a chance alignment of galaxies with an isotropic or mildly flattened distribution (probability $= {0.0015}$).
description: 24 pages, 16 figures, 7 tables. Accepted for publication by the Monthly Notices of the Royal Astronomical Society in this form
Remarks on regular black holes
Creators: name: Nicolini, Piero
name: Smailagic, Anais
name: Spallucci, Euro
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Recently it has been claimed by Chinaglia and Zerbini that the curvature singularity is present even in the so-called regular black hole solutions of the Einstein equations. In this brief note we show that this criticism is devoid of any physical content.
description: v1: 8 pages; v2: 6 pages, title changed, version matching that in press on Int. J. Geom. Meth. Mod. Phys
Quantum state conversion in opto-electro-mechanical systems via shortcut to adiabaticity
Creators: name: Zhou, Xiao
name: Liu, Bao-Jie
name: Shao, L. -B.
name: Zhang, Xin-Ding
name: Xue, Zheng-Yuan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Adiabatic process has found many important applications in modern physics, the distinct merit of which is that it does not need accurate control over the timing of the process. However, it is a slow process, which limits the application in quantum computation, due to the limited coherent times of typical quantum systems. Here, we propose a scheme to implement quantum state conversion in opto-electro-mechanical systems via shortcut to adiabaticity, where the process can be greatly speeded up while the precise timing control is still not necessary. In our scheme, only by modifying the coupling strength, we can achieve fast quantum state conversion with high fidelity, where the adiabatic condition does not need to be met. In addition, the population of the unwanted intermediate state can be further suppressed. Therefore, our protocol presents an important step towards practical state conversion between optical and microwave photons, and thus may find many important applications in hybrid quantum information processing.
description: v2: Accepted version; v3: publishend version with typoes corrected