cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Exploratory Control with Tsallis Entropy for Latent Factor Models
Creators: name: Donnelly, Ryan
name: Jaimungal, Sebastian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Finance (q-fin.MF)
subject: FOS: Economics and business

description: We study optimal control in models with latent factors where the agent controls the distribution over actions, rather than actions themselves, in both discrete and continuous time. To encourage exploration of the state space, we reward exploration with Tsallis Entropy and derive the optimal distribution over states - which we prove is $q$-Gaussian distributed with location characterized through the solution of an FBS$Δ$E and FBSDE in discrete and continuous time, respectively. We discuss the relation between the solutions of the optimal exploration problems and the standard dynamic optimal control solution. Finally, we develop the optimal policy in a model-agnostic setting along the lines of soft $Q$-learning. The approach may be applied in, e.g., developing more robust statistical arbitrage trading strategies.
Revisited cold gas content with atomic carbon [C I] in z=2.5 protocluster galaxies
Creators: name: Lee, Minju M.
name: Tanaka, Ichi
name: Iono, Daisuke
name: Kawabe, Ryohei
name: Kodama, Tadayuki
name: Kohno, Kotaro
name: Saito, Toshiki
name: Tamura, Yoichi
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We revisit the cold gas contents of galaxies in a protocluster at z=2.49 using the lowest neutral atomic carbon transition [CI]$^3$P$_1$-$^3$P$_0$ from Atacama Large Millimeter/submillimeter Array observations. We aim to test if the same gas mass calibration applied in field galaxies can be applied to protocluster galaxies. Five galaxies out of sixteen targeted galaxies are detected in the [CI] line, and these are all previously detected in CO(3-2) and CO(4-3) and three in 1.1 mm dust continuum. We investigate the line luminosity relations between CO and [CI] in the protocluster and compare them with other previous studies. We then compare the gas mass based on three gas tracers of [CI], CO(3-2), and dust if at least one of the last two tracers are available. Using the calibration adopted for field main-sequence galaxies, the [CI]-based gas measurements are lower than or comparable to the CO-based gas measurements by -0.35 dex at the lowest with the mean deviation of -0.14 dex. The differences between [CI]- and the dust- based measurements are relatively mild by up to 0.16 dex with the mean difference of 0.02 dex. Taking these all together with calibration uncertainties, with the [CI] line, we reconfirm our previous findings that the mean gas fraction is comparable to field galaxies for a stellar-mass range of $\log(M_{\rm star}/M_\odot = [10.6, 11.3]$. However, at least for these secure five detections, the depletion time scale decreases more rapidly with stellar mass than field galaxies that might be related to earlier quenching in dense environments.
description: accepted for publication in ApJ
A novel analytic atmospheric $T(τ)$ relation for stellar models
Creators: name: Ball, Warrick H.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Stellar models often use relations between the temperature $T$ and optical depth $τ$ to evaluate the structure of their optically-thin outer layers. We fit a novel analytic function to the Hopf function $q(τ)$ of a radiation-coupled hydrodynamics simulation of near-surface convection with solar parameters by Trampedach et al. (2014). The fit is accurate to within 0.82 per cent for the solar simulation and to within 13 per cent for all the simulations that are not on either the low-temperature or low-gravity edges of the grid of simulations.
description: 3 pages, 1 figure
On the Twisted q-Euler numbers and polynomials associated with basic q-l-functions
Creators: name: Kim, T.
name: Rim, S. H.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11B68

description: One purpose of this paper is to construct twisted q-Euler numbers by using p-adic invariant integral on Zp in the sense of fermionic. Finally, we consider twisted Euler q-zeta function and q-l-series which interpolate twisted q-Euler numbers and polynomials.
description: 8 pages
Autonomous Assessment of Demonstration Sufficiency via Bayesian Inverse Reinforcement Learning
Creators: name: Trinh, Tu
name: Chen, Haoyu
name: Brown, Daniel S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: We examine the problem of determining demonstration sufficiency: how can a robot self-assess whether it has received enough demonstrations from an expert to ensure a desired level of performance? To address this problem, we propose a novel self-assessment approach based on Bayesian inverse reinforcement learning and value-at-risk, enabling learning-from-demonstration ("LfD") robots to compute high-confidence bounds on their performance and use these bounds to determine when they have a sufficient number of demonstrations. We propose and evaluate two definitions of sufficiency: (1) normalized expected value difference, which measures regret with respect to the human's unobserved reward function, and (2) percent improvement over a baseline policy. We demonstrate how to formulate high-confidence bounds on both of these metrics. We evaluate our approach in simulation for both discrete and continuous state-space domains and illustrate the feasibility of developing a robotic system that can accurately evaluate demonstration sufficiency. We also show that the robot can utilize active learning in asking for demonstrations from specific states which results in fewer demos needed for the robot to still maintain high confidence in its policy. Finally, via a user study, we show that our approach successfully enables robots to perform at users' desired performance levels, without needing too many or perfectly optimal demonstrations.
description: Prior version appears in proceedings of AAAI FSS-22 Symposium "Lessons Learned for Autonomous Assessment of Machine Abilities (LLAAMA)". Current version appears in proceedings of HRI '24, March 11-14, 2024, Boulder, CO, USA
The Hierarchical Structure of Galactic Haloes: Classification and characterisation with Halo-OPTICS
Creators: name: Oliver, William H.
name: Elahi, Pascal J.
name: Lewis, Geraint F.
name: Power, Chris
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We build upon Ordering Points To Identify Clustering Structure (OPTICS), a hierarchical clustering algorithm well-known to be a robust data-miner, in order to produce Halo-OPTICS, an algorithm designed for the automatic detection and extraction of all meaningful clusters between any two arbitrary sizes. We then apply Halo-OPTICS to the 3D spatial positions of halo particles within four separate synthetic Milky Way type galaxies, classifying the stellar and dark matter structural hierarchies. Through visualisation of the Halo-OPTICS output, we compare its structure identification to the state-of-the-art galaxy/(sub)halo finder VELOCIraptor, finding excellent agreement even though Halo-OPTICS does not consider kinematic information in this current implementation. We conclude that Halo-OPTICS is a robust hierarchical halo finder, although its determination of lower spatial-density features such as the tails of streams could be improved with the inclusion of extra localised information such as particle kinematics and stellar metallicity into its distance metric.
description: 18 pages, 12 figures, 2 tables. Accepted by MNRAS
Quantum walks on quotient graphs
Creators: name: Krovi, Hari
name: Brun, Todd A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A discrete-time quantum walk on a graph is the repeated application of a unitary evolution operator to a Hilbert space corresponding to the graph. If this unitary evolution operator has an associated group of symmetries, then for certain initial states the walk will be confined to a subspace of the original Hilbert space. Symmetries of the original graph, given by its automorphism group, can be inherited by the evolution operator. We show that a quantum walk confined to the subspace corresponding to this symmetry group can be seen as a different quantum walk on a smaller quotient graph. We give an explicit construction of the quotient graph for any subgroup of the automorphism group and illustrate it with examples. The automorphisms of the quotient graph which are inherited from the original graph are the original automorphism group modulo the subgroup used to construct it. We then analyze the behavior of hitting times on quotient graphs. Hitting time is the average time it takes a walk to reach a given final vertex from a given initial vertex. It has been shown in earlier work [Phys. Rev. A {\bf 74}, 042334 (2006)] that the hitting time can be infinite. We give a condition which determines whether the quotient graph has infinite hitting times given that they exist in the original graph. We apply this condition for the examples discussed and determine which quotient graphs have infinite hitting times. All known examples of quantum walks with fast hitting times correspond to systems with quotient graphs much smaller than the original graph; we conjecture that the existence of a small quotient graph with finite hitting times is necessary for a walk to exhibit a quantum speed-up.
description: 18 pages, 7 figures in EPS format
Efficient Adversarial Input Generation via Neural Net Patching
Creators: name: Khan, Tooba
name: Madhukar, Kumar
name: Sharma, Subodh Vishnu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: The generation of adversarial inputs has become a crucial issue in establishing the robustness and trustworthiness of deep neural nets, especially when they are used in safety-critical application domains such as autonomous vehicles and precision medicine. However, the problem poses multiple practical challenges, including scalability issues owing to large-sized networks, and the generation of adversarial inputs that lack important qualities such as naturalness and output-impartiality. This problem shares its end goal with the task of patching neural nets where small changes in some of the network's weights need to be discovered so that upon applying these changes, the modified net produces the desirable output for a given set of inputs. We exploit this connection by proposing to obtain an adversarial input from a patch, with the underlying observation that the effect of changing the weights can also be brought about by changing the inputs instead. Thus, this paper presents a novel way to generate input perturbations that are adversarial for a given network by using an efficient network patching technique. We note that the proposed method is significantly more effective than the prior state-of-the-art techniques.
Quantum Deformations of the One-Dimensional Hubbard Model
Creators: name: Beisert, Niklas
name: Koroteev, Peter
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Algebra (math.QA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: The centrally extended superalgebra psu(2|2)xR^3 was shown to play an important role for the integrable structures of the one-dimensional Hubbard model and of the planar AdS/CFT correspondence. Here we consider its quantum deformation U_q(psu(2|2)xR^3) and derive the fundamental R-matrix. From the latter we deduce an integrable spin chain Hamiltonian with three independent parameters and the corresponding Bethe equations to describe the spectrum on periodic chains. We relate our Hamiltonian to a two-parametric Hamiltonian proposed by Alcaraz and Bariev which can be considered a quantum deformation of the one-dimensional Hubbard model.
description: 58 pages, v2: comments on Alcaraz-Bariev cases A+- extended, references added, v3: addresses corrected
Regularization of the Covariant Derivative on Curved Space by Finite Matrices
Creators: name: Hanada, Masanori
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In a previous paper [M.~Hanada, H.~Kawai and Y.~Kimura, Prog. Theor. Phys. 114 (2005), 1295] it is shown that a covariant derivative on any n-dimensional Riemannian manifold can be expressed in terms of a set of n matrices, and a new interpretation of IIB matrix model, in which the diffeomorphism, the local Lorentz symmetry and their higher spin analogues are embedded in the unitary symmetry, is proposed. In this article we investigate several coset manifolds in this formulation and show that on these backgrounds, it is possible to carry out calculations at the level of finite matrices by using the properties of the Lie algebras. We show how the local fields and the symmetries are embedded as components of matrices and how to extract the physical degrees of freedom satisfying the constraint proposed in the previous paper.
description: 21pages, no figure, to appear in Prog. Theor. Phys
CryptoCredit: Securely Training Fair Models
Creators: name: de Castro, Leo
name: Chen, Jiahao
name: Polychroniadou, Antigoni
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: Cryptography and Security (cs.CR)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: E.3; I.2.0; J.4
subject: 62J02, 68P25, 94A60

description: When developing models for regulated decision making, sensitive features like age, race and gender cannot be used and must be obscured from model developers to prevent bias. However, the remaining features still need to be tested for correlation with sensitive features, which can only be done with the knowledge of those features. We resolve this dilemma using a fully homomorphic encryption scheme, allowing model developers to train linear regression and logistic regression models and test them for possible bias without ever revealing the sensitive features in the clear. We demonstrate how it can be applied to leave-one-out regression testing, and show using the adult income data set that our method is practical to run.
description: 8 pages
SPIDERS: An Overview of The Largest Catalogue of Spectroscopically Confirmed X-ray Galaxy Clusters
Creators: name: Kirkpatrick, C. C.
name: Clerc, N.
name: Finoguenov, A.
name: Damsted, S.
name: Chitham, J. Ider
name: Kukkola, A. E.
name: Gueguen, A.
name: Furnell, K.
name: Rykoff, E.
name: Comparat, J.
name: Saro, A.
name: Capasso, R.
name: Padilla, N.
name: Erfanianfar, G.
name: Mamon, G. A.
name: Collins, C.
name: Merloni, A.
name: Brownstein, J. R.
name: Schneider, D. P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: SPIDERS is the spectroscopic follow-up effort of the Sloan Digital Sky Survey IV (SDSS-IV) project for the identification of X-ray selected galaxy clusters. We present our catalogue of 2740 visually inspected galaxy clusters as a part of the SDSS Data Release 16 (DR16). Here we detail the target selection, our methods for validation of the candidate clusters, performance of the survey, the construction of the final sample, and a full description of what is found in the catalogue. Of the sample, the median number of members per cluster is approximately 10, with 818 having 15 or greater. We find that we are capable of validating over 99% of clusters when 5 redshifts are obtained below $z<0.3$ and when 9 redshifts are obtained above $z>0.3$. We discuss the improvements of this catalogue's identification of cluster using 33,340 redshifts, with $Δz_{\rm{phot}} / Δz_{\rm{spec}} \sim 100$, over other photometric and spectroscopic surveys, as well as present an update to previous ($σ- L_{X}$) and ($σ- λ$) relations. Finally, we present our cosmological constraints derived using the velocity dispersion function.
description: 16 pages, 14 figures, Accepted for publication in MNRAS
Hardware Implementation of Spiking Neural Networks Using Time-To-First-Spike Encoding
Creators: name: Oh, Seongbin
name: Kwon, Dongseok
name: Yeom, Gyuho
name: Kang, Won-Mook
name: Lee, Soochang
name: Woo, Sung Yun
name: Kim, Jang Saeng
name: Park, Min Kyu
name: Lee, Jong-Ho
Publisher: name: arXiv
Year: 2020
Subjects: subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: Hardware-based spiking neural networks (SNNs) are regarded as promising candidates for the cognitive computing system due to low power consumption and highly parallel operation. In this work, we train the SNN in which the firing time carries information using temporal backpropagation. The temporally encoded SNN with 512 hidden neurons showed an accuracy of 96.90% for the MNIST test set. Furthermore, the effect of the device variation on the accuracy in temporally encoded SNN is investigated and compared with that of the rate-encoded network. In a hardware configuration of our SNN, NOR-type analog memory having an asymmetric floating gate is used as a synaptic device. In addition, we propose a neuron circuit including a refractory period generator for temporally encoded SNN. The performance of the 2-layer neural network consisting of synapses and proposed neurons is evaluated through circuit simulation using SPICE. The network with 128 hidden neurons showed an accuracy of 94.9%, a 0.1% reduction compared to that of the system simulation of the MNIST dataset. Finally, the latency and power consumption of each block constituting the temporal network is analyzed and compared with those of the rate-encoded network depending on the total time step. Assuming that the total time step number of the network is 256, the temporal network consumes 15.12 times lower power than the rate-encoded network and can make decisions 5.68 times faster.
Renormalizable Extension of the Abelian Higgs-Kibble Model with a Dim.6 Derivative Operator
Creators: name: Binosi, Daniele
name: Quadri, Andrea
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We present a new approach to the consistent subtraction of a non power-counting renormalizable extension of the Abelian Higgs-Kibble (HK) model supplemented by a dim.6 derivative-dependent operator controlled by the parameter $z$. A field-theoretic representation of the physical Higgs scalar by a gauge-invariant variable is used in order to formulate the theory by exploiting a novel differential equation, controlling the dependence of the quantized theory on $z$. These results pave the way to the consistent subtraction by a finite number of physical parameters of some non-power-counting renormalizable models possibly of direct relevance to the study of the Higgs potential at the LHC.
description: 9 pages. Minor changes and some comments added. Submitted to the proceedings of GROUP34 - The 34th International Colloquium on Group Theoretical Methods in Physics, 18-22 July 2022, Strasbourg, France
Tailed frogs (Ascaphus truei, Stejneger) in natural and managed coastal temperate rainforests of southwestern British Columbia, Canada
Creators: name: Wahbe, Tanya Rhoda
Publisher: name: University of British Columbia
Year: 2009

description: Ten headwater creeks were surveyed for tailed frog tadpoles in the summers of 1994 and 1995 to assess possible effects of timber harvest on their population density and structure. Three watersheds were selected to replicate three treatments: old-growth (250+yrs), mature second growth (60-80yrs) and young clearcut (~5yrs). One buffered clearcut creek was located and sampled but not replicated. Creek and site characteristics modified the response forest harvest had on tailed frog tadpole populations. Effects on tailed frog tadpoles associated with forest harvest depended on elevation, creek size, percent sand cover and percent riffle cover. Higher tadpole biomass per unit area and density were associated with high elevation sites, small creeks and low percent cover of riffles. Both average tadpole mass and snout-vent length were found to increase with increasing percent sand cover. Tadpoles appear to select microhabitats of pool, run or riffle depending on their body size or stage of development. Higher tadpole densities are also associated with lower creek temperatures. Old-growth and buffered clearcut creeks showed highest biomass per unit area and density of tailed frog tadpoles. Old-growth creeks also exhibited more tadpole cohorts (5 'year-classes'), higher tadpole biomass per unit area but lower average mass than clearcuts. Low (3 m maximum) tadpole movements were detected in clearcut creeks, while longer distance (65m maximum) movements were detected within old-growth creeks. Harvesting history appears to be an indirect measure of the factors influencing the population dynamics of tailed frogs, whereas aspects of microhabitat, which can vary in parallel with forest age, are probably the true limiting factors. Structural features of old-growth forests are also influenced by gradient, elevation and disturbance history. In my study, more than 85% of the variation in tadpole biomass per unit area and tadpole density was associated with creek and site characteristics. History of forest disturbance only had a major impact under specific conditions. When managing for tailed frogs, the variability of creek and site characteristics must be considered prior to making harvesting decisions.
Sample-Efficient Safety Assurances using Conformal Prediction
Creators: name: Luo, Rachel
name: Zhao, Shengjia
name: Kuck, Jonathan
name: Ivanovic, Boris
name: Savarese, Silvio
name: Schmerling, Edward
name: Pavone, Marco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: When deploying machine learning models in high-stakes robotics applications, the ability to detect unsafe situations is crucial. Early warning systems can provide alerts when an unsafe situation is imminent (in the absence of corrective action). To reliably improve safety, these warning systems should have a provable false negative rate; i.e. of the situations that are unsafe, fewer than $ε$ will occur without an alert. In this work, we present a framework that combines a statistical inference technique known as conformal prediction with a simulator of robot/environment dynamics, in order to tune warning systems to provably achieve an $ε$ false negative rate using as few as $1/ε$ data points. We apply our framework to a driver warning system and a robotic grasping application, and empirically demonstrate guaranteed false negative rate while also observing low false detection (positive) rate.
description: International Journal of Robotics Research, 2023
PANSATZ: Pulse-based Ansatz for Variational Quantum Algorithms
Creators: name: Meirom, Dekel
name: Frankel, Steven H.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We develop and implement a novel pulse-based ansatz, which we call PANSATZ, for more efficient and accurate implementations of variational quantum algorithms (VQAs) on today's noisy intermediate-scale quantum (NISQ) computers. Our approach is applied to quantum chemistry. Specifically, finding the ground-state energy associated with the electron configuration problem, using the variational quantum eigensolver (VQE) algorithm for several molecules. We manage to achieve chemical accuracy both in simulation for several molecules and on one of IBM's NISQ devices for the $H_2$ molecule in the STO-3G basis. Our results are compared to a gate-based ansatz and show significant latency reduction - up to $7\times$ shorter ansatz schedules. We also show that this ansatz has structured adaptivity to the entanglement level required by the problem.
An investigation of flare emissions at multiple wavelengths
Creators: name: Li, Dong
name: Warmuth, Alexander
name: Lu, Lei
name: Ning, Zongjun
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability Experiment and Geostationary Orbiting Environmental Satellites. Then their locations and geometries are identified from the full-disk images measured by the Atmospheric Imaging Assembly (AIA), and the time delays among the light curves in different channels are identified. The electron number densities are estimated using the Differential Emission Measure method. We find that three of four flares show strong emissions in SXR channels and high temperature (>6 MK) EUV wavelengths during the impulsive phase, i.e., AIA 131 A and 94 A, and then they emit peak radiation subsequently in the middle temperature (~0.6-3 MK) EUV channels. Moreover, they last for a long time and have smaller electron densities, which are probably driven by the interaction of hot diffuse flare loops. Only one flare emits radiation at almost the same time in all the observed wavelengths, lasts for a relatively short time, and has a larger electron density. It is also accompanied by a type III radio burst. The bright emission at the EUV channel could be corresponding to the associated erupting filament.
description: 16 pages, 9 figures, accepted for publication in RAA
GBT Observations of IC 443: the Nature of OH(1720 MHz) Masers and OH Absorption
Creators: name: Hewitt, John W.
name: Yusef-Zadeh, Farhad
name: Wardle, Mark
name: Roberts, Douglas A.
name: Kassim, Namir E.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present results of spectral line observations of the ground state transitions of hydroxyl(OH) toward supernova remnant IC 443 carried out with the Green Bank Telescope. At a spatial resolution of 7.2 arcminutes we detect weak, extended OH(1720 MHz) maser emission with OH(1667/5,1612 MHz) absorption along the southern extent of the remnant, where no bright compact maser sources have been observed previously. These newly detected SNR-type masers are coincident with known molecular clumps and a ridge of shocked molecular hydrogen indicative of the SNR shock front interacting with the adjacent molecular cloud. Simultaneous observation of all four ground-state transitions of OH permits us to fit physical conditions of the shocked gas at the interaction site. A simple two-component model for the line profiles yields the physical parameters for detected regions of maser emission including excitation temperature, OH column density and filling factor. Observed line profiles suggest the shock is largely propagating toward the line-of-sight in the region of these newly identified weak masers. The implications of shock geometry and physical parameters in producing extended OH maser emission in SNRs are explored. We also present VLA radio continuum observations at 330 MHz for comparison with OH line observations of the remnant.
description: 20 pages, 4 figures, 3 tables, submitted to ApJ
Productivity, costs, and optimal spacing of skyline corridors of two cable yarding systems in partial cutting of second-growth forests of coastal British Columbia
Creators: name: Rutherford, Dag
Publisher: name: University of British Columbia
Year: 2009

description: Public pressure to end clearcut logging, and changing forest management needs have increased opportunities for partial cutting in British Columbia's second-growth coastal forests. Production economics and engineering design of cable harvesting systems for partial cutting in second-growth forests of British Columbia (BC) are largely unknown. Scientific research and working experience in partial cutting forest harvesting operations in coastal areas of the Pacific Northwest of North America is from the United States or from selection harvesting of old growth forests in coastal BC prior to 1935. Time and motion studies were conducted in fall of the 1992 and spring of 1993 on two cable yarders in second growth coastal forests (on Vancouver Island) of BC. The goals of the studies were to design a forest engineering system for field layout of cable harvesting systems in partial cutting, develop production and cost models for the two yarders , compare the productivity and costs of partial cutting and clearcutting, and develop models for optimal spacing of skyline yarding corridors. Results showed that forest engineering of partial cutting with cable yarders was dependent upon corridor spacing and tailspar tree location, size and species. Production and cost analyses showed that wider corridors and larger crew sizes were more efficient, but also that productivity gains from larger crew sizes did not result in lower operating costs. Clearcutting in all instances was shown to be more efficient and cost effective than partial cutting. The coastal stumpage appraisal system was shown to vastly under-estimate the added costs of partial cutting in relation to clearcutting. Optimal skyline corridor analysis and comparisons demonstrated that lower variable yarding costs resulted from wider corridor spacing, both contractors spaced yarding corridors narrower than optimal, and costs could be reduced by optimal spacing of corridors. The quantity of timber harvested with partial cutting is increasing annually, and knowledge and experience in these harvesting systems is necessary and will be an asset.
QCD phase structure in strong magnetic fields
Creators: name: Ding, H. -T.
name: Li, S. -T.
name: Shi, Q.
name: Tomiya, A.
name: Wang, X. -D.
name: Zhang, Y.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: In this proceedings we discuss the natural connection between the reduction of neutral pion mass in the vacuum, and the magnetic catalysis as well as the reduction of transition temperature in the external magnetic field. We also present the first results on fluctuations of and correlations among conserved charges in strong magnetic fields from lattice QCD computations.
description: 12 pages, 7 figures, Invited talk in the online Workshop on Criticality in QCD and Hadron Resonance Gas, July 29-31, 2020, Wroclaw, Poland, to be published in the proceedings
Variational approach to fluid-structure interaction via GENERIC
Creators: name: Peschka, Dirk
name: Zafferi, Andrea
name: Heltai, Luca
name: Thomas, Marita
Publisher: name: Weierstrass Institute
Year: 2021
Subjects: subject: Fluid-structure interaction
subject: damped Hamiltonian system
subject: transformations
subject: 74F10
subject: 70H33
subject: 35A15
subject: 65M60

description: We present a framework to systematically derive variational formulations for fluid-structure interaction problems based on thermodynamical driving functionals and geometric structures in different coordinate systems by suitable transformations within this formulation. Our approach provides a promising basis to construct structure-preserving discretization strategies.
Experimental single-impulse magnetic focusing of launched cold atoms
Creators: name: Smith, David A.
name: Arnold, Aidan S.
name: Pritchard, Matthew J.
name: Hughes, Ifan G.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Single-impulse three-dimensional magnetic focusing of vertically launched cold atoms has been observed. Four different configurations of the lens were used to vary the relative radial and axial focusing properties. Compact focused clouds of 85Rb were seen for all four configurations. It is shown that an atom-optical ray matrix approach for describing the lensing action is insufficient. Numerical simulation using a full approximation to the lens's magnetic field shows very good agreement with the radial focusing properties of the lens. However, the axial (vertical direction) focusing properties are less well described and the reasons for this are discussed.
description: Revised to incorporate referee suggestions, final version
BLAST: A Wafer-scale Transfer Process for Heterogeneous Integration of Optics and Electronics
Creators: name: Ji, Yanxin
name: Cortese, Alejandro J.
name: Smart, Conrad L.
name: Molnar, Alyosha C.
name: McEuen, Paul L.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: We present a general transfer method for the heterogeneous integration of different photonic and electronic materials systems and devices onto a single substrate. Called BLAST, for Bond, Lift, Align, and Slide Transfer, the process works at wafer scale and offers precision alignment, high yield, varying topographies, and suitability for subsequent lithographic processing. We demonstrate BLAST's capabilities by integrating both GaAs and GaN microLEDs with silicon photovoltaics to fabricate optical wireless integrated circuits that up-convert photons from the red to the blue. We also show that BLAST can be applied to a variety of other devices and substrates, including CMOS electronics, vertical cavity surface emitting lasers (VCSELs), and 2D materials. BLAST further enables the modularization of optoelectronic microsystems, where optical devices fabricated on one material substrate can be lithographically integrated with electronic devices on a different substrate in a scalable process.
From the Kubo formula to variable range hopping
Creators: name: Cohen, Doron
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Consider a multichannel closed ring with disorder. In the semiclassical treatment its conductance is given by the Drude formula. Quantum mechanics challenge this result both in the limit of strong disorder (eigenstates are not quantum-ergodic in real space) and in the limit of weak disorder (eigenstates are not quantum-ergodic in momentum space). Consequently the analysis of conductance requires going beyond linear response theory, leading to a resistor network picture of transitions between energy levels. We demonstrate that our semi-linear response theory provides a firm unified framework from which the "hopping" phenomenology of Mott can be derived.
description: 5 pages, published version with an extended concluding paragraph
Error-Mitigated Quantum Simulation of Interacting Fermions with Trapped Ions
Creators: name: Chen, Wentao
name: Zhang, Shuaining
name: Zhang, Jialiang
name: Su, Xiaolu
name: Lu, Yao
name: Zhang, Kuan
name: Qiao, Mu
name: Li, Ying
name: Zhang, Jing-Ning
name: Kim, Kihwan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Quantum error mitigation has been extensively explored to increase the accuracy of the quantum circuits in noisy-intermediate-scale-quantum (NISQ) computation, where quantum error correction requiring additional quantum resources is not adopted. Among various error-mitigation schemes, probabilistic error cancellation (PEC) has been proposed as a general and systematic protocol that can be applied to numerous hardware platforms and quantum algorithms. However, PEC has only been tested in two-qubit systems and a superconducting multi-qubit system by learning a sparse error model. Here, we benchmark PEC using up to four trapped-ion qubits. For the benchmark, we simulate the dynamics of interacting fermions with or without spins by applying multiple Trotter steps. By tomographically reconstructing the error model and incorporating other mitigation methods such as positive probability and symmetry constraints, we are able to increase the fidelity of simulation and faithfully observe the dynamics of the Fermi-Hubbard model, including the different behavior of charge and spin of fermions. Our demonstrations can be an essential step for further extending systematic error-mitigation schemes toward practical quantum advantages.
description: 15 pages, 11 figures
Sustained magneto-shear instabilities in the solar tachocline
Creators: name: Miesch, Mark S.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present nonlinear three-dimensional simulations of the stably-stratified portion of the solar tachocline in which the rotational shear is maintained by mechanical forcing. When a broad toroidal field profile is specified as an initial condition, a clam-shell instability ensues which is similar to the freely-evolving cases studied previously. After the initial nonlinear saturation, the residual mean fields are apparently too weak to sustain the instability indefinitely. However, when a mean poloidal field is imposed in addition to the rotational shear, a statistically-steady state is achieved in which the clam-shell instability is operating continually. This state is characterized by a quasi-periodic exchange of energy between the mean toroidal field and the instability mode with a longitudinal wavenumber m=1. This quasi-periodic behavior has a timescale of several years and may have implications for tachocline dynamics and field emergence patterns throughout the solar activity cycle.
description: 5 pages, 3 figures (eps format). Fig. 3 also in jpg format. Submitted to Astrophysical Journal Letters
Maximization and Minimization of Interfacial Thermal Conductance by Modulating the Mass Distribution of Interlayer
Creators: name: Yang, Lina
name: Wan, Xiao
name: Ma, Dengke
name: Jiang, Yi
name: Yang, Nuo
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Tuning interfacial thermal conductance has been a key task for the thermal management of nanoelectronic devices. Here, it is studied how the interfacial thermal conductance is great influenced by modulating the mass distribution of the interlayer of one-dimensional atomic chain. By nonequilibrium Green's function and machine learning algorithm, the maximum/minimum value of thermal conductance and its corresponding mass distribution are calculated. Interestingly, the mass distribution corresponding to the maximum thermal conductance is not a simple function, such as linear and exponential distribution predicted in previous works, it is similar to a sinusoidal curve around linear distribution for larger thickness interlayer. Further, the mechanism of the abnormal results is explained by analyzing the phonon transmission spectra and density of states. The work provides deep insight into optimizing and designing interfacial thermal conductance by modulating mass distribution of interlayer atoms.
Nonlinear bias toward complex contagion in uncertain transmission settings
Creators: name: St-Onge, Guillaume
name: Hébert-Dufresne, Laurent
name: Allard, Antoine
Publisher: name: arXiv
Year: 2023
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Current epidemics in the biological and social domains are challenging the standard assumptions of mathematical contagion models. Chief among them are the complex patterns of transmission caused by heterogeneous group sizes and infection risk varying by orders of magnitude in different settings, like indoor versus outdoor gatherings in the COVID-19 pandemic or different moderation practices in social media communities. However, quantifying these heterogeneous levels of risk is difficult and most models typically ignore them. Here, we include these novel features in an epidemic model on weighted hypergraphs to capture group-specific transmission rates. We study analytically the consequences of ignoring the heterogeneous transmissibility and find an induced superlinear infection rate during the emergence of a new outbreak, even though the underlying mechanism is a simple, linear contagion. The dynamics produced at the individual and group levels are therefore more similar to complex, nonlinear contagions, thus blurring the line between simple and complex contagions in realistic settings. We support this claim by introducing a Bayesian inference framework to quantify the nonlinearity of contagion processes. We show that simple contagions on real weighted hypergraphs are systematically biased toward the superlinear regime if the heterogeneity of the weights is ignored, greatly increasing the risk of erroneous classification as complex contagions. Our results provide an important cautionary tale for the challenging task of inferring transmission mechanisms from incidence data. Yet, it also paves the way for effective models that capture complex features of epidemics through nonlinear infection rates.
description: 19 pages, 5 figures
Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides
Creators: name: Lengers, F.
name: Kuhn, T.
name: Reiter, D. E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Localized excitons play a vital role in the optical response of monolayers of transition metal dichalcogenides and can be exploited as single photon sources for quantum information technology. While the optical properties of such localized excitons are vastly studied, the ultrafast capture process of delocalized excitons into localized potentials is largely unexplored. We perform quantum kinetic calculations of exciton capture via acoustic and optical phonons showing that efficient capture takes place on an ultrafast time scale. The polaron formation in the low-temperature limit leads to higher-energy excitons which can then be efficiently trapped. We demonstrate that the interplay of acoustic and optical phonons leads to an efficient broadening of energy-selection rules. Our studies provide a deep understanding of the carrier trapping from two-dimensional materials into zero-dimensional potentials.
Remaking e refashioning "A Midsummer Night’s Dream": cartoons, fumetti, manga e graphic novels
Creators: name: Cioni, Fernando
Publisher: name: LEA - Lingue e Letterature d'Oriente e d'Occidente
Year: 2021

description: I drammi di Shakespeare hanno subito trasformazioni radicali nei modi in cui sono stati messi in scena e recepiti nel corso dei secoli. Nel ventesimo e ventunesimo secolo, i drammi sono stati adattati, localizzati, appropriati attraverso media diversi: teatro, cinema, musica, fumetti e cartoni animati. Questo articolo si focalizzerà sull'appropriazione di A Midsummer Night's Dream in forma di cartone animato e fumetto, mettendo a confronto versioni diverse e media diversi, dalla versione con le marionette di Jiri Trnka agli animated tales, alla versione manga adattata da Richard Appignanesi e illustrata da Kate Brown, alla graphic novel di Neil Gaiman.
description: LEA - Lingue e Letterature d'Oriente e d'Occidente, Vol. 10 (2021)
Giant Molecular Cloud Catalogues for PHANGS-ALMA: Methods and Initial Results
Creators: name: Rosolowsky, Erik
name: Hughes, Annie
name: Leroy, Adam K.
name: Sun, Jiayi
name: Querejeta, Miguel
name: Schruba, Andreas
name: Usero, Antonio
name: Herrera, Cinthya N.
name: Liu, Daizhong
name: Pety, Jérôme
name: Saito, Toshiki
name: Bešlić, Ivana
name: Bigiel, Frank
name: Blanc, Guillermo
name: Chevance, Mélanie
name: Dale, Daniel A.
name: Deger, Sinan
name: Faesi, Christopher M.
name: Glover, Simon C. O.
name: Henshaw, Jonathan D.
name: Klessen, Ralf S.
name: Kruijssen, J. M. Diederik
name: Larson, Kirsten
name: Lee, Janice
name: Meidt, Sharon
name: Mok, Angus
name: Schinnerer, Eva
name: Thilker, David A.
name: Williams, Thomas G.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present improved methods for segmenting CO emission from galaxies into individual molecular clouds, providing an update to the CPROPS algorithms presented by Rosolowsky & Leroy (2006; arXiv:astro-ph/0601706 ). The new code enables both homogenization of the noise and spatial resolution among data, which allows for rigorous comparative analysis. The code also models the completeness of the data via false source injection and includes an updated segmentation approach to better deal with blended emission. These improved algorithms are implemented in a publicly available python package, PYCPROPS. We apply these methods to ten of the nearest galaxies in the PHANGS-ALMA survey, cataloguing CO emission at a common 90 pc resolution and a matched noise level. We measure the properties of 4986 individual clouds identified in these targets. We investigate the scaling relations among cloud properties and the cloud mass distributions in each galaxy. The physical properties of clouds vary among galaxies, both as a function of galactocentric radius and as a function of dynamical environment. Overall, the clouds in our target galaxies are well-described by approximate energy equipartition, although clouds in stellar bars and galaxy centres show elevated line widths and virial parameters. The mass distribution of clouds in spiral arms has a typical mass scale that is 2.5x larger than interarm clouds and spiral arms clouds show slightly lower median virial parameters compared to interarm clouds (1.2 versus 1.4).
description: Accepted to MNRAS. Catalogues, code, and atlas available at http://phangs.org/data
KonsortSWD
Creators: name: Miller, Bernhard
name: Zindler, Susanne
Publisher: name: Zenodo
Year: 2020
Subjects: FDM
Forschungsdatenmanagement
Hessische Forschungsdateninfrastrukturen
NFDI
Nationale Forschungsdateninfrastrukturen
KonsortSWD
Präsentation
HeFDI Plenary 2020

description: Poster über die Aufgaben und Ziele von KonsortSWD - Konsortium für die Sozial-, Verhaltens-, Bildungs- und Wirtschaftswissenschaften, präsentiert am HeFDI Plenary 2020.