cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Discrete surface growth process as a synchronization mechanism for scale free complex networks
Creators: name: Piontti, A. L. Pastore y
name: Macri, P. A.
name: Braunstein, L. A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We consider the discrete surface growth process with relaxation to the minimum [F. Family, J. Phys. A {\bf 19} L441, (1986).] as a possible synchronization mechanism on scale-free networks, characterized by a degree distribution $P(k) \sim k^{-λ}$, where $k$ is the degree of a node and $λ$ his broadness, and compare it with the usually applied Edward-Wilkinson process [S. F. Edwards and D. R. Wilkinson, Proc. R. Soc. London Ser. A {\bf 381},17 (1982) ]. In spite of both processes belong to the same universality class for Euclidean lattices, in this work we demonstrate that for scale-free networks with exponents $λ<3$ this is not true. Moreover, we show that for these ubiquitous cases the Edward-Wilkinson process enhances spontaneously the synchronization when the system size is increased, which is a non-physical result. Contrarily, the discrete surface growth process do not present this flaw and is applicable for every $λ$.
description: 8 pages, 4 figures
Visualization in syllogistic reasoning
Creators: name: Osana, Helena Patricia
Publisher: name: University of British Columbia
Year: 2010

description: The purpose of this study was to compare the effects of three different methods for teaching syllogistic reasoning. Two of the instructional methods contained visual constructs and the other consisted only of non-visual (verbal) explanations. The literature suggested that visual aids enhance performance in problem solving tasks. Of primary concern, therefore, were the effects of the visual methods compared to the non-visual approach. All methods were developed for the micro-computer. The visual approaches were modelled after two theories of syllogistic reasoning behaviour. Erickson (1974) provided the basis for the Venn diagram method and Johnson-Laird & Steedman (1978) developed the necessary details for the Sample Representation method. The findings of this study were: (1) The Venn diagram method resulted in significantly greater syllogistic reasoning than both the Sample Representation and the Non-visual methods. (2) Surprisingly, the Non-visual method resulted in significantly greater syllogistic reasoning than the Sample Representation method.
Revisiting Empirical Solar Energetic Particle Scaling Relations II. Coronal Mass Ejections
Creators: name: Papaioannou, Athanasios
name: Herbst, Konstantin
name: Ramm, Tobias
name: Lario, David
name: Veronig, Astrid M.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: Aims. The space radiation environment conditions and the maximum expected coronal mass ejection (CME) speed are being assessed through the investigation of scaling laws between the peak proton flux and fluence of Solar Energetic Particle (SEP) events with the speed of the CMEs. Methods. We utilize a complete catalog of SEP events, covering the last ~25 years of CME observations (i.e. 1997 to 2017). We calculate the peak proton fluxes and integrated event fluences for those events reaching an integral energy of up to E> 100 MeV, covering the period of the last ~25 years of CME observations. For a sample of 38 strong SEP events, we first investigate the statistical relations between the recorded peak proton fluxes (IP) and fluences (FP) at a set of integral energies of E >10 MeV, E>30 MeV, E>60 MeV, and E>100 MeV versus the projected CME speed near the Sun (VCME) obtained by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph (SOHO/LASCO). Based on the inferred relations, we further calculate the integrated energy dependence of both IP and FP, assuming that they follow an inverse power-law with respect to energy. By making use of simple physical assumptions, we combine our derived scaling laws to estimate the upper limits for VCME, IP, and FP focusing on two cases of known extreme SEP events that occurred on February 23, 1956 (GLE05) and in AD774/775, respectively. Given physical constraints and assumptions, several options for the upper limit VCME, associated with these events, are investigated. Results. A scaling law relating IP and FP to the CME speed as V^{5}CME for CMEs ranging between ~3400-5400 km/s is consistent with values of FP inferred for the cosmogenic nuclide event of AD774/775. At the same time, the upper CME speed that the current Sun can provide possibly falls within an upper limit of VCME <= 5500 km/s.
Electron-electron interaction and charging effects in graphene quantum dots
Creators: name: Wunsch, B.
name: Stauber, T.
name: Guinea, F.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We analyze charging effects in graphene quantum dots. Using a simple model, we show that, when the Fermi level is far from the neutrality point, charging effects lead to a shift in the electrostatic potential and the dot shows standard Coulomb blockade features. Near the neutrality point, surface states are partially occupied and the Coulomb interaction leads to a strongly correlated ground state which can be approximated by either a Wigner crystal or a Laughlin like wave function. The existence of strong correlations modify the transport properties which show non equilibrium effects, similar to those predicted for tunneling into other strongly correlated systems.
description: Extended version accepted for publication at Phys. Rev. B
Relativistic Iron K Emission and absorption in the Seyfert 1.9 galaxy MCG-5-23-16
Creators: name: Braito, V.
name: Reeves, J. N.
name: Dewangan, G. C.
name: George, I.
name: Griffiths, R. E.
name: Markowitz, A.
name: Nandra, K.
name: Porquet, D.
name: Ptak, A.
name: Turner, T. J.
name: Yaqoob, T.
name: Weaver, K.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the results of the simultaneous deep XMM and Chandra observations of the bright Seyfert 1.9 galaxy MCG-5-23-16, which is thought to have one of the best known examples of a relativistically broadened iron K-alpha line. The time averaged spectral analysis shows that the iron K-shell complex is best modeled with an unresolved narrow emission component (FWHM < 5000 km/s, EW ~ 60 eV) plus a broad component. This latter component has FWHM ~ 44000 km/s and EW ~ 50 eV. Its profile is well described by an emission line originating from an accretion disk viewed with an inclination angle ~ 40^\circ and with the emission arising from within a few tens of gravitational radii of the central black hole. The time-resolved spectral analysis of the XMM EPIC-pn spectrum shows that both the narrow and broad components of the Fe K emission line appear to be constant in time within the errors. We detected a narrow sporadic absorption line at 7.7 keV which appears to be variable on a time-scale of 20 ksec. If associated with Fe XXVI Ly-alpha this absorption is indicative of a possibly variable, high ionization, high velocity outflow. The variability of this absorption feature appears to rule out a local (z=0) origin. The analysis of the XMM RGS spectrum reveals that the soft X-ray emission of MCG-5-23-16 is likely dominated by several emission lines superimposed on an unabsorbed scattered power-law continuum. The lack of strong Fe L shell emission together with the detection of a strong forbidden line in the O VII triplet is consistent with a scenario where the soft X-ray emission lines are produced in a plasma photoionized by the nuclear emission.
description: 45 pages, 12 figures, 4 tables, accepted for publication in ApJ
The observed mass distribution of Galactic black hole LMXBs is biased against massive black holes
Creators: name: Jonker, Peter G.
name: Kaur, Karamveer
name: Stone, Nicholas
name: Torres, Manuel A. P.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The discovery of gravitational wave radiation from merging black holes (BHs) also uncovered BHs with masses in the range of ~20-160 Msun. In contrast, the most massive Galactic stellar-mass BH currently known has a mass ~21 Msun. While low-mass X-ray binaries (LMXBs) will never independently evolve into a binary BH system, and binary evolution effects can play an important role explaining the different BH masses found through studies of X-ray binaries and gravitational wave events, (electromagnetic) selection effects may also play a role in this discrepancy. Assuming BH LMXBs originate in the Galactic Plane, we show that the spatial distribution of the current sample of confirmed and candidate BH LMXBs are both biased to sources that lie at a large distance from the Plane. Specifically, most of the confirmed and candidate BH LMXBs are found at a Galactic height larger than 3 times the scale height for massive star formation. In addition, the confirmed BH LMXBs are found at larger distances to the Galactic Center than the candidate BH LMXBs. Interstellar absorption makes candidate BH LMXBs in the Plane and those in the Bulge too faint for a dynamical mass measurement using current instrumentation. Given the observed and theoretical evidence for BH natal and/or Blaauw kicks, their relation with BH mass and binary orbital period, and the relation between outburst recurrence time and BH mass, the observational selection effects imply that the current sample of confirmed BH LMXBs is biased against the most massive BHs.
description: 17 pages, 3 figures, 2 tables, accepted for publication in ApJ
Spectacular Shells in the Host Galaxy of the QSO MC2 1635+119
Creators: name: Canalizo, Gabriela
name: Bennert, Nicola
name: Jungwiert, Bruno
name: Stockton, Alan
name: Schweizer, Francois
name: Lacy, Mark
name: Peng, Chien
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present deep HST/ACS images and Keck spectroscopy of MC2 1635+119, a QSO hosted by a galaxy previously classified as an undisturbed elliptical. Our new images reveal dramatic shell structure indicative of a merger event in the relatively recent past. The brightest shells in the central regions of the host are distributed alternately in radius, with at least two distinct shells on one side of the nucleus and three on the other, out to a distance of ~13 kpc. The light within the five shells comprises ~6% of the total galaxy light. Lower surface brightness ripples or tails and other debris extend out to a distance of ~65 kpc. A simple N-body model for a merger reproduces the inner shell structure and gives an estimate for the age of the merger between ~30 Myr and ~1.7 Gyr, depending on a range of reasonable assumptions. While the inner shell structure is suggestive of a minor merger, the total light contribution from the shells and extended structures are more indicative of a major merger. The spectrum of the host galaxy is dominated by a population of intermediate age (~1.4 Gyr), indicating a strong starburst episode that may have occurred at the time of the merger event. We speculate that the current QSO activity may have been triggered in the recent past by either a minor merger, or by debris from an older (~Gyr) major merger that is currently ``raining'' back into the central regions of the merger remnant.
description: 14 pages, 5 figures. Accepted for publication in the Astrophysical Journal
Two-dimensional simulations of disks in close binaries: Simulating outburst cycles in cataclysmic variables
Creators: name: Jordan, Lucas M.
name: Wehner, Dennis
name: Kuiper, Rolf
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Previous simulations of cataclysmic variables studied either the quiescence, or the outburst state in multiple dimensions or they simulated complete outburst cycles in one dimension using simplified models for the gravitational torques. We self-consistently simulate complete outburst cycles of normal and superoutbursts in cataclysmic variable systems in two dimensions. We study the effect of different $α$ viscosity parameters, mass transfer rates, and binary mass ratios on the disk luminosities, outburst occurrence rates, and superhumps. We simulate non-isothermal, viscous accretion disks in cataclysmic variable systems using a modified version of the FARGO code with an updated equation of state and a cooling function designed to reproduce s-curve behavior. Our simulations can model complete outburst cycles using the thermal tidal instability model. We find higher superhump amplitudes and stronger gravitational torques than previous studies, resulting in better agreement with observations.
description: Accepted in A&A. 21 pages, 27 figures
Quantitative insights into the phase behaviour and miscibility of organic photovoltaic active layers from the perspective of neutron spectroscopy
Creators: name: Zbiri, Mohamed
name: Finn, Peter A.
name: Nielsen, Christian B.
name: Guilbert, Anne A. Y.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We present a neutron spectroscopy based method to study quantitatively the partial miscibility and phase behaviour of an organic photovoltaic active layer made of conjugated polymer:small molecule blends, presently illustrated with the regio-random poly(3-hexylthiophene-2,5-diyl) and fullerene [6,6]-Phenyl C$_{61}$ butyric acid methyl ester (RRa-P3HT:PCBM) system. We perform both inelastic neutron scattering and quasi-elastic neutron scattering measurements to study the structural dynamics of blends of different compositions enabling us to resolve the phase behaviour. The difference of neutron cross sections between RRa-P3HT and PCBM, and the use of deuteration technique, offer a unique opportunity to probe the miscibility limit of fullerene in the amorphous polymer-rich phase and to tune the contrast between the polymer and the fullerene phases, respectively. Therefore, the proposed approach should be universal and relevant to study new non-fullerene acceptors that are closely related - in terms of chemical structures - to the polymer, where other conventional imaging and spectroscopic techniques present a poor contrast between the blend components.
The dispersion measure and rotation measure from fast radio burst host galaxies based on the IllustrisTNG50 simulation
Creators: name: Kovacs, Timea Orsolya
name: Mao, Sui Ann
name: Basu, Aritra
name: Ma, Yik Ki
name: Spitler, Laura G.
name: Walker, Charles R. H.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Fast radio bursts (FRB) will become important cosmological tools, as the number of observed FRBs is increasing rapidly with more surveys being carried out. A large sample of FRBs with dispersion measures (DM) and rotation measures (RM) can be used to study the intergalactic magnetic field. However, the observed DM and RM of FRBs have multiple contributors which must be quantified to obtain the intergalactic medium's (IGM) DM and RM. In this paper, we estimate one such contribution to DM and RM: that of FRB host galaxies. We show how it changes with redshift, galaxy type, and the stellar mass of the galaxies, inclination, and FRB's projected offset. Using the IllustrisTNG50 simulations, we selected 16500 galaxies at redshifts of 0<=z<=2, with stellar masses in the range 9<=log(M*/Msun)<=12. In each galaxy, we calculate the DM and RM contributions of 1000 sightlines, and construct DM and RM probability density functions. We find that the rest frame DM distributions of all galaxies at a given redshift can be fitted by a lognormal function, and the rest frame RM distribution is symmetric around 0 rad m$^{-2}$, and can be fitted by the combination of a Lorentzian and two Gaussian functions. The parameters of these functions change for different subsets of galaxies with different redshift, stellar mass, inclination, and FRB offset. These changes are due to an increasing $n_e$ with redshift, SFR, and stellar mass, and we find a more ordered B field at lower z compared to higher z, suggested by more galaxies with B field reversals and B fields dominated by random B field at higher z. We estimate the FRB host DM and RM contributions, which can be used in the future to isolate the IGM's contribution from the observed DM and RM of FRBs. We predict that to constrain an $σ_{\rm RM,IGM}$ of 2 rad m$^{-2}$ to 95% confidence level we need to observe 95000 FRBs at z=0.5, but only 9500 FRBs at z=2.
description: 24 pages, 15 figures Accepted for publication in A&A
Irradiation effect and binary radio pulsars with giant companions
Creators: name: Lan, Shunyi
name: Meng, Xiangcun
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Pulsars are neutron stars that rotate rapidly. Most of the pulsars in binary systems tend to spin faster than those in isolation. According to binary evolution theory, radio pulsars in binary systems can have various types of companion stars. However, binary radio pulsars with giant stars, helium stars, and black holes as companions are lacking so far. We aim to investigate the possible parameter space of binary radio pulsars with giant companions. We used the MESA stellar evolution code to consider the effect of irradiation in binary evolution and evolved a series of binary models. We present the potential physical properties of binary radio pulsars with giant star companions in the framework of the classical recycling scenario and the irradiation model. We found that the parameter space of binary radio pulsars with giant companions can be greatly expanded by the effect of irradiation. Moreover, when irradiation is strong enough, submillisecond pulsars might be accompanied by giant companion stars. We also demonstrate a correlation between the timescale of the binary system as a low-mass X-ray binary and the irradiation efficiency. The birthrate problem between millisecond pulsars and low-mass X-ray binaries might not be resolved by the irradiation effect. A more detailed binary population synthesis is necessary. Our findings may offer guidance for observers that wish to locate binary radio pulsars with giant companions or submillisecond pulsars.
description: Accepted for publication in Astronomy & Astrophysics
A low-energy limit of Yang-Mills theory on de Sitter space
Creators: name: Cork, Josh
name: Kutluk, Emine Şeyma
name: Lechtenfeld, Olaf
name: Popov, Alexander D.
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We consider Yang--Mills theory with a compact structure group $G$ on four-dimensional de Sitter space dS$_4$. Using conformal invariance, we transform the theory from dS$_4$ to the finite cylinder ${\cal I}\times S^3$, where ${\cal I}=(-π/2, π/2)$ and $S^3$ is the round three-sphere. By considering only bundles $P\to{\cal I}\times S^3$ which are framed over the temporal boundary $\partial{\cal I}\times S^3$, we introduce additional degrees of freedom which restrict gauge transformations to be identity on $\partial{\cal I}\times S^3$. We study the consequences of the framing on the variation of the action, and on the Yang--Mills equations. This allows for an infinite-dimensional moduli space of Yang--Mills vacua on dS$_4$. We show that, in the low-energy limit, when momentum along ${\cal I}$ is much smaller than along $S^3$, the Yang--Mills dynamics in dS$_4$ is approximated by geodesic motion in the infinite-dimensional space ${\cal M}_{\rm vac}$ of gauge-inequivalent Yang--Mills vacua on $S^3$. Since ${\cal M}_{\rm vac}\cong C^\infty (S^3, G)/G$ is a group manifold, the dynamics is expected to be integrable.
description: 1+23 pages. v2: introduction extended, theory modifications clarified, references updated
Assessing Non-Nested Configurations of Multifidelity Machine Learning for Quantum-Chemical Properties
Creators: name: Vinod, Vivin
name: Zaspel, Peter
Publisher: name: arXiv
Year: 2024
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Machine Learning (cs.LG)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Multifidelity machine learning (MFML) for quantum chemical (QC) properties has seen strong development in the recent years. The method has been shown to reduce the cost of generating training data for high-accuracy low-cost ML models. In such a set-up, the ML models are trained on molecular geometries and some property of interest computed at various computational chemistry accuracies, or fidelities. These are then combined in training the MFML models. In some multifidelity models, the training data is required to be nested, that is the same molecular geometries are included to calculate the property across all the fidelities. In these multifidelity models, the requirement of a nested configuration restricts the kind of sampling that can be performed while selection training samples at different fidelities.
 This work assesses the use of non-nested training data for two of these multifidelity methods, namely MFML and optimized MFML (o-MFML). The assessment is carried out for the prediction of ground state energies and first vertical excitation energies of a diverse collection of molecules of the CheMFi dataset. Results indicate that the MFML method still requires a nested structure of training data across the fidelities. However, the o-MFML method shows promising results for non-nested multifidelity training data with model errors comparable to the nested configurations.
Goldstone boson decays and chiral anomalies
Creators: name: Pokorski, Stefan
name: Sakurai, Kazuki
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Martinus Veltman was the first to point out the inconsistency of the experimental value for the decay rate of $π^0\rightarrowγγ$ and its calculation by J. Steinberger with the very successful concept of the pion as the (pseudo)Nambu-Goldstone boson of the spontaneously broken global axial symmetry of strong interactions. That inconsistency has been resolved by J. Bell and R. Jackiw in their famous paper on the chiral anomalies. We review the connection between the decay amplitudes of an axion into two gauge bosons in Abelian vector-like and chiral gauge theories. The axion is the Nambu-Goldstone boson of a spontaneously broken axial global symmetry of the theory. Similarly as for the vector-like gauge theory, also in the chiral one the axion decay amplitude is determined by the anomaly of the current of the axial symmetry in its non-linear realization. Certain subtlety in the calculation of the anomaly in chiral gauge theories is emphasised.
description: 12 pages, Contribution to the special volume of Acta Physica Polonica B commemorating Martinus Veltman
Simplified Chain Inflation
Creators: name: Huang, Qing-Guo
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We propose a simplified chain inflation model and calculate the primordial power spectra of the scalar and tensor fluctuations. The spectral index and the tensor-scalar ratio are respectively 0.972 and 0.089 which are consistent with present cosmological observations.
description: 8 pages, 1 figure; refs added
The retention of secondary school metalworking knowledge and skills following three months of no training
Creators: name: Neufeld, Leslie John
Publisher: name: University of British Columbia
Year: 2010

description: An underlying assumption of an educational system is that the learning which takes place will be of present and future use to the learner. When this learning is not retained well, this underlying assumption is called into question. In no subject area is the use of learning a greater priority than in Industrial Education. Here the value of knowledge and skills is largely dependent on usefulness to the learner. For the present study the researcher developed two measuring instruments. One was a multiple choice instrument that measured knowledge that was needed in the development of psycho-motor skills, and knowledge that was not so needed. Both of these types of learning were separated into mastery level learning and non-mastery level learning. The other instrument measured level of achievement of a continuous psycho-motor skill, namely arc welding. Tests were administered in June to a class of Metal work 11 students, then administered again in September to the same students as they entered Metalwork 12. Multivariate analysis of variance tests were conducted to determine any differences in retention rates. The results indicated that knowledge used in the development of psycho-motor skills was retained well, as was the psycho-motor skill itself. Mastery level learning suffered significant losses unless it was used in the development of skills. Knowledge not used in the development of skills suffered significant losses. Several variables were investigated to determine their effects on retention of these types of knowledge. This study is of use to administrators and Industrial Education teachers as they decide on appropriate methods of implementing Industrial Education curricula.
An International Ultraviolet Explorer Archival Study of Dwarf Novae in Outburst
Creators: name: Hamilton, Ryan T.
name: Urban, Joel A.
name: Sion, Edward M.
name: Riedel, Adric R.
name: Voyer, Elysse N.
name: Marcy, John T.
name: Lakatos, Sarah L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a synthetic spectral analysis of nearly the entire far ultraviolet International Ultraviolet Explorer (IUE) archive of spectra of dwarf novae in or near outburst. The study includes 46 systems of all dwarf nova subtypes both above and below the period gap. The spectra were uniformly analyzed using synthetic spectral codes for optically thick accretion disks and stellar photospheres along with the best-available distance measurements or estimates. We present newly estimated accretion rates and discuss the implications of our study for disk accretion physics and CV evolution.
description: Accepted for publication in the ApJ, Part 1
Thermodynamics and the quantum speed limit in the non-Markovian regime
Creators: name: Das, Arpan
name: Bera, Anindita
name: Chakraborty, Sagnik
name: Chruściński, Dariusz
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum speed limit (QSL) for open quantum systems in the non-Markovian regime is analyzed. We provide a the lower bound for the time required to transform an initial state to a final state in terms of thermodynamic quantities such as the energy fluctuation, entropy production rate and dynamical activity. Such bound was already analyzed for Markovian evolution satisfying detailed balance condition. Here we generalize this approach to deal with arbitrary evolution governed by time-local generator. Our analysis is illustrated by three paradigmatic examples of qubit evolution: amplitude damping, pure dephasing, and the eternally non-Markovian evolution.
description: 10 pages, 4 figures. Close to published version
Multiwavelength Monitoring of the Unusual Ultraluminous Supernova SN 1978K in NGC 1313 and the Search for an Associated Gamma-Ray Burst
Creators: name: Smith, I. A.
name: Ryder, S. D.
name: Boettcher, M.
name: Tingay, S. J.
name: Stacy, A.
name: Pakull, M.
name: Liang, E. P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We discuss our radio (Australia Telescope Compact Array and Australian Long Baseline Array) and X-ray (XMM-Newton) monitoring observations of the unusual ultraluminous supernova SN 1978K in NGC 1313 at ~25 years after the explosion. SN 1978K is a rare example of a Type IIn supernova that has remained bright enough to have long-term X-ray and radio observations. The observations probe the dense medium that was ejected by the progenitor star prior to its explosion; the star might have been a Luminous Blue Variable. The radio imaging shows that the source remains compact, but it may be marginally resolved. The radio monitoring shows deviations from a smooth decay suggesting that inhomogeneities are present in the radio emitting region. It appears that a major change occurred in the mass-loss rate of the progenitor star shortly before the supernova event. The X-ray emission between 2000 and 2006 is consistent with the radiation coming from two shocks. All the X-ray data can be fit using the same model (with no systematic evolution or short-term variability) but this has a surprising requirement: the X-ray emitting regions have a very large abundance of helium. This would be consistent with the X-ray emitting shocks being located in a helium-rich layer that was ejected by the progenitor star, or helium-rich material was ejected in the supernova explosion. The unusual properties of the supernova motivated a search for an associated gamma-ray burst (GRB). We show that SN 1978K was inside the ~4 sigma error box of GRB 771029. If this association is correct, the GRB was exceptionally underluminous. However, the quality of the gamma-ray burst locations at that time was poor, and this is likely just a chance alignment.
description: 23 pages, 3 tables, 4 figures (2 color). Astrophysical Journal, in press (scheduled for November 10, 2007)
Simultaneous Operations in a Two-Dimensional Array of Singlet-Triplet Qubits
Creators: name: Fedele, Federico
name: Chatterjee, Anasua
name: Fallahi, Saeed
name: Gardner, Geoffrey C.
name: Manfra, Michael J.
name: Kuemmeth, Ferdinand
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In many physical approaches to quantum computation, error-correction schemes assume the ability to form two-dimensional qubit arrays with nearest-neighbor couplings and parallel operations at multiple qubit sites. While semiconductor spin qubits exhibit long coherence times relative to their operation speed and single-qubit fidelities above error correction thresholds, multiqubit operations in two-dimensional arrays have been limited by fabrication, operation, and readout challenges. We present a two-by-two array of four singlet-triplet qubits in gallium arsenide and show simultaneous coherent operations and four-qubit measurements via exchange oscillations and frequency-multiplexed single-shot measurements. A larger multielectron quantum dot is fabricated in the center of the array as a tunable interqubit link, which we utilize to demonstrate coherent spin exchange with selected qubits. Our techniques are extensible to other materials, indicating a path towards quantum processors with gate-controlled spin qubits.
description: Revised version after peer review, with additional supporting data. 13 pages, 9 figures (including 4-page 4-figure supplement)
Interaction of vector light beams with atoms exposed to a time-dependent magnetic field
Creators: name: Ramakrishna, Shreyas
name: Schmidt, Riaan P.
name: Peshkov, Anton A.
name: Franke-Arnold, Sonja
name: Surzhykov, Andrey
name: Fritzsche, Stephan
Publisher: name: arXiv
Year: 2024
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: During recent years interest has been rising for applications of vector light beams towards magnetic field sensing. In particular, a series of experiments were performed to extract information about properties of static magnetic fields from absorption profiles of light passing through an atomic gas target. In the present work, we propose an extension to this method for oscillating magnetic fields. To investigate this scenario, we carried out theoretical analysis based on the time-dependent density matrix theory. We found that absorption profiles, even when averaged over typical observation times, are indeed sensitive to both strength and frequency of the time-dependent field, thus opening the prospect for a powerful diagnostic technique. To illustrate this sensitivity, we performed detailed calculations for the $5s \;\, {}^2S_{1/2}$ ($F=1$) $-$ $5p \;\, {}^2 P_{3/2}$ ($F=0$) transition in rubidium atoms, subject to a superposition of an oscillating (test) and a static (reference) magnetic field.
description: 10 pages, 9 figures
ALMA-IMF XV: The core mass function in the high-mass star-formation regime
Creators: name: Louvet, F.
name: Sanhueza, P.
name: Stutz, A.
name: Men'shchikov, A.
name: Motte, F.
name: Galván-Madrid, R.
name: Bontemps, S.
name: Pouteau, Y.
name: Ginsburg, A.
name: Csengeri, T.
name: Di Francesco, J.
name: Dell'Ova, P.
name: González, M.
name: Didelon, P.
name: Braine, J.
name: Cunningham, N.
name: Thomasson, B.
name: Lesaffre, P.
name: Hennebelle, P.
name: Bonfand, M.
name: Gusdorf, A.
name: Álverez-Gutiérrez, R. H.
name: Nony, T.
name: Busquet, G.
name: Olguin, F.
name: Bronfman, L.
name: Salinas, J.
name: Fernandez-Lopez, M.
name: Moraux, E.
name: Liu, H. L.
name: Lu, X.
name: Huei-Ru, V.
name: Towner, A.
name: Valeille-Manet, M.
name: Brouillet, N.
name: Herpin, F.
name: Lefloch, B.
name: Baug, T.
name: Maud, L.
name: Lopez-Sepulcre, A.
name: Svodoba, B.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The stellar initial mass function (IMF) is critical to our understanding of star formation and the effects of young stars on their environment. On large scales, it enables us to use tracers such as UV or Halpha emission to estimate the star formation rate of a system and interpret unresolved star clusters across the universe. So far, there is little firm evidence of large-scale variations of the IMF, which is thus generally considered universal. Stars form from cores and it is now possible to estimate core masses and compare the core mass function (CMF) with the IMF, which it presumably produces. The goal of the ALMA-IMF large program is to measure the core mass function at high linear resolution (2700 au) in 15 typical Milky Way protoclusters spanning a mass range of 2500 to 32700 Msun. In this work, we used two different core extraction algorithms to extract about 680 gravitationally bound cores from these 15 protoclusters. We adopt per core temperature using the temperature estimate from the PPMAP Bayesian method. A power-law fit to the CMF of the sub-sample of cores above the 1.64 Msun completeness limit, 330 cores, through the maximum likelihood estimate technique yields a slope of 1.97 +/- 0.06, significantly flatter than the 2.35 Salpeter slope. Assuming a self-similar mapping between the CMF and the IMF, this result implies that these 15 high-mass protoclusters will generate atypical IMFs. This sample is the largest to date produced and analysed self-consistently, derived at matched physical resolution, with per-core temperature estimates and cores as massive as 150 Msun. We provide the raw source extraction catalogues and the source derived size, temperature, mass, and spectral indices in the 15 protoclusters.
description: Accepted by A&A
Performance of Non-Parametric Reconstruction Techniques in the Late-Time Universe
Creators: name: Escamilla-Rivera, Celia
name: Said, Jackson Levi
name: Mifsud, Jurgen
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In the context of a Hubble tension problem that is growing in its statistical significance, we reconsider the effectiveness of non-parametric reconstruction techniques which are independent of prescriptive cosmological models. By taking cosmic chronometers, Type Ia Supernovae and baryonic acoustic oscillation data, we compare and contrast two important reconstruction approaches, namely Gaussian processes (GP) and the \textbf{Lo}cally w\textbf{e}ighted \textbf{S}catterplot \textbf{S}moothing together with \textbf{Sim}ulation and \textbf{ex}trapolation method (LOESS-Simex or LS). In the context of these methods, besides not requiring a cosmological model, they also do not require physical parameters in their approach to their reconstruction of data (but they do depend on statistical hyperparameters). We firstly show how both GP and LOESS-Simex can be used to successively reconstruct various data sets to a high level of precision. We then directly compare both approaches in a quantitative manner by considering several factors, such as how well the reconstructions approximate the data sets themselves to how their respective uncertainties evolve. In light of the puzzling Hubble tension, it is important to consider how the uncertain regions evolve over redshift and the methods compare for estimating cosmological parameters at current times. For cosmic chronometers and baryonic acoustic oscillation compiled data sets, we find that GP generically produce smaller variances for the reconstructed data with a minimum value of $σ_{\rm GP-min} = 1.1$, while the situation for LS is totally different with a minimum of $σ_{\rm LS-min} = 50.8$. Moreover, some of these characteristics can be alleviate at low $z$, where LS presents less underestimation in comparison to GP.
description: 22 pages, 5 figures, 3 tables. Version accepted in JCAP
Clump Lifetimes and the Initial Mass Function
Creators: name: Clark, Paul C.
name: Klessen, Ralf S.
name: Bonnell, Ian A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recent studies of dense clumps/cores in a number of regions of low-mass star formation have shown that the mass distribution of these clumps closely resembles the initial mass function (IMF) of field stars. One possible interpretation of these observations is that we are witnessing the fragmentation of the clouds into the IMF, and the observed clumps are bound pre-stellar cores. In this paper, we highlight a potential difficulty in this interpretation, namely that clumps of varying mass are likely to have systematically varying lifetimes. This timescale problem can effectively destroy the similarity bewteen the clump and stellar mass functions, such that a stellar-like clump mass function (CMF) results in a much steeper stellar IMF. We also discuss some ways in which this problem may be avoided.
description: 7 pages, 3 figures, accepted to MNRAS
Dimensional reduction and adaptation-development-evolution relation in evolved biological systems
Creators: name: Kaneko, Kunihiko
Publisher: name: arXiv
Year: 2024
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Life systems are complex and hierarchical, with diverse components at different scales, yet they sustain themselves, grow, and evolve over time. How can a theory of such complex biological states be developed? Here we note that for a hierarchical biological system to be robust, it must achieve consistency between micro-scale (e.g. molecular) and macro-scale (e.g. cellular) phenomena. This allows for a universal theory of adaptive change in cells based on biological robustness and consistency between cellular growth and molecular replication. Here, we show how adaptive changes in high-dimensional phenotypes (biological states) are constrained to low-dimensional space, leading to the derivation of a macroscopic law for cellular states. The theory is then extended to evolution, leading to proportionality between evolutionary and environmental responses, as well as proportionality between phenotypic variances due to noise and due to genetic changes. The universality of the results across several models and experiments is demonstrated. Then, by further extending the theory of evolutionary dimensional reduction to multicellular systems, the relationship between multicellular development and evolution, in particular the developmental hourglass, is demonstrated. Finally, the possibility of collapse of dimensional reduction under nutrient limitation is discussed.
description: Review as a proceeding paper for IUPAB conference
Topological Magnus responses in two and three dimensional systems
Creators: name: Das, Sanjib Kumar
name: Nag, Tanay
name: Nandy, Snehasish
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Recently, time-reversal symmetric but inversion broken systems with non-trivial Berry curvature in the presence of a built-in electric field have been proposed to exhibit a new type of linear Hall effect in ballistic regime, namely, the Magnus Hall effect. The transverse current here is caused by the Magnus velocity that is proportional to the built-in electric field allowing us to examine the Magnus Hall conductivity and Magnus Nernst conductivity with chemical potential. Starting with two-dimensional (2D) topological systems, we find that warping induced asymmetry in both the Fermi surface and Berry curvature can in general enhance the Magnus Hall response for monolayer graphene and surface states of topological insulator. Interestingly, strain can change the Fermi surface character substantially that further results in distinct behavior of Magnus transport coefficients as we observe in bilayer graphene. Going beyond 2D systems, we also investigate the Magnus Hall and Nernst responses in three-dimensional multi-Weyl semimetals (mWSMs). Remarkably, Magnus responses can only survive for the tilted WSMs, and therefore can be measured as a tool to distinguish between the untilted and tilted WSMs in experiments. In addition, we find that the Magnus Hall responses get suppressed with increasing the non-linearity associated with the band touching around multi-Weyl node.
description: 16 pages, 10 figures
The interpretation of metaphor
Creators: name: Romaniw, Irene
Publisher: name: University of British Columbia
Year: 2010

description: This thesis attempts to explain exactly how it is that we interpret metaphor. A brief historical overview of the substitution, comparison and interaction methods is offered. Then the basic steps within these theories are aligned with current thoughts on the interpretation of metaphor from within semantic theory. Because of the self-imposed restrictions within semantic theory, a semantic interpretation of metaphor is an extremely limited one. The problems of definition of meaning, the allowance of deviant language and the nature of the relationship between syntax and semantics are considered before adapting Samuel Levin's Semantics of Metaphor. Levin offers a formula, based on semantic theory, whereby a good basic framework is provided to outline the steps involved in the understanding of metaphor. By extending Levin's theory and by testing this extended version against complex metaphor, a more comprehensive approach to the interpretation of metaphor is offered. Furthermore, application of the extended theory to increasingly complex metaphors reveals a consistent and predictable pattern traceable throughout the interpretation process which, in turn, can only be reflective of the organizational patterns of human thought.
Early Planet Formation in Embedded Disks (eDisk) XVI: An asymmetric dust disk driving a multi-component molecular outflow in the young Class 0 protostar GSS30 IRS3
Creators: name: Santamaria-Miranda, Alejandro
name: de Gregorio-Monsalvo, Itziar
name: Ohashi, Nagayoshi
name: Tobin, John J.
name: Sai, Jinshi
name: Jorgensen, Jes K.
name: Aso, Yusuke
name: Lin, Zhe-Yu Daniel
name: Flores, Christian
name: Kido, Miyu
name: Koch, Patrick M.
name: Kwon, Woojin
name: Lee, Chang Won
name: Li, Zhi-Yun
name: Looney, Leslie W.
name: Plunkett, Adele L.
name: Takakuwa, Shigehisa
name: Hoff, Merel L. R van t
name: Williams, Jonathan P.
name: Yen, Hsi-Wei
Publisher: name: arXiv
Year: 2024
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the results of the ALMA Large Program Early Planet Formation in Embedded disks observations of the Class 0 protostar GSS30 IRS3. Our observations included 1.3 mm continuum with a resolution of 0.''05 (7.8 au) and several molecular species including $^{12}$CO, $^{13}$CO, C$^{18}$O, H$_{2}$CO and c-C$_{3}$H$_{2}$. The dust continuum analysis unveiled a disk-shaped structure with a major axis size of $\sim$200 au. We observed an asymmetry in the minor axis of the continuum emission suggesting that the emission is optically thick and the disk is flared. On the other hand, we identified two prominent bumps along the major axis located at distances of 26 and 50 au from the central protostar. The origin of the bumps remains uncertain and might be due to an embedded substructure within the disk or the result of the temperature distribution instead of surface density due to optically thick continuum emission. The $^{12}$CO emission reveals a molecular outflow consisting of three distinct components: a collimated one, an intermediate velocity component exhibiting an hourglass shape, and a wider angle low-velocity component. We associate these components with the coexistence of a jet and a disk-wind. The C$^{18}$O emission traces both a Keplerian rotating circumstellar disk and the infall of the rotating envelope. We measured a stellar dynamical mass of 0.35$\pm$0.09 M$_{\odot}$.
description: 25 pages, 19 figures. Accepted for publication in A&A
On Randomness in Quantum Mechanics
Creators: name: de la Torre, Alberto C.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The quantum mechanical probability densities are compared with the probability densities treated by the theory of random variables. The relevance of their difference for the interpretation of quantum mechanics is commented.
Kirillov-Reshetikhin conjecture : the general case
Creators: name: Hernandez, David
Publisher: name: arXiv
Year: 2007
Subjects: subject: Quantum Algebra (math.QA)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: We prove the Kirillov-Reshetikhin (KR) conjecture in the general case : for all twisted quantum affine algebras we prove that the characters of KR modules solve the twisted Q-system and we get explicit formulas for the character of their tensor products (the untwisted simply-laced case was treated by Najakima, and the untwisted case by the author). The proof is uniform and provides several new developments for the representation theory of twisted quantum affine algebras, including twisted Frenkel-Reshetikhin q-characters (expected by Frenkel-Reshetikhin and Frenkel-Mukhin). We also prove the twisted T-system. As an application we get explicit formulas for the twisted q-characters of fundamental representations for all types, including the formulas for types D_4^{(3)}, E_6^{(2)} conjectured by Reshetikhin. We prove the formulas for KR modules in types A_n^{(2)} and D_4^{(3)} conjectured by Kuniba-Suzuki. Eventually our results imply the conjectural branching rules [HKOTT] to the quantum subalgebra of finite type.
description: 81 pages, 4 figures. The Drinfeld-Serre relations are not used in the proofs