cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The ISM scaling relations using inner HI and an application of estimating dust mass
Creators: name: Li, Fujia
name: Wang, Jing
name: Xu, Fengwei
name: Kong, Xu
name: Chen, Xinkai
name: Lin, Zesen
name: Wang, Shun
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We select a disk-like galaxy sample with observations of the $HI$, $H_{2}$ and dust from Herschel Reference Survey (HRS), and derive inner HI masses within the optical radius. We find that the inner gas-to-dust ratio is almost independent of gas-phase metallicity, and confirm that the inner gas mass ($HI$+$H_{2}$) shows tighter relationship with dust mass and monochromatic 500 $μm$ luminosity than the integral gas mass. It supports that dust is more closely associated with co-spatial cold gas than the overall cold gas. Based on the newly calibrated relationship between inner gas mass and dust mass, we predict dust masses for disk-dominated galaxies from the xCOLD GASS sample. The predicted dust masses show scaling relations consistent with fiducial ones in the literature, supporting their robustness. Additionally, we find that at a given dust mass and star formation rate (SFR), the galactic WISE W3 luminosities show significant dependence on the [NII] luminosity and the stellar mass surface density. Such dependence highlights the caveat of using the W3 luminosity as integral SFR indicator, and is consistent with findings of studies which target star-forming regions in more nearby galaxies and accurately derive dust masses based on mapping-mode spectroscopy.
description: 21 pages, 8 figures, 3 tables. Accepted for Publication in ApJ
A perspective on the landscape problem
Creators: name: Smolin, Lee
Publisher: name: arXiv
Year: 2012
Subjects: subject: History and Philosophy of Physics (physics.hist-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: I discuss the historical roots of the landscape problem and propose criteria for its successful resolution. This provides a perspective to evaluate the possibility to solve it in several of the speculative cosmological scenarios under study including eternal inflation, cosmological natural selection and cyclic cosmologies.
description: Invited contribution for a special issue of Foundations of Physics titled: Forty Years Of String Theory: Reflecting On the Foundations. 31 pages, no figures
Ferromagnetism in graphene nanoribbons: split versus oxidative unzipped ribbons
Creators: name: Rao, S. S.
name: Jammalamadaka, S. Narayana
name: Stesmans, A.
name: Moshchalkov, V. V.
name: van Tol, J.
name: Kosynkin, D. V.
name: Higginbotham, A.
name: Tour, J. M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Two types of graphene nanoribbons: (a) potassium-split graphene nanoribbons (GNRs), and (b) oxidative unzipped and chemically converted graphene nanoribbons (CCGNRs) were investigated for their magnetic properties using the combination of static magnetization and electron spin resonance measurements. The two types of ribbons possess remarkably different magnetic properties. While the low temperature ferromagnet-like feature is observed in both types of ribbons, such room temperature feature persists only in potassium-split ribbons. The GNRs show negative exchange bias, but the CCGNRs exhibit a 'positive exchange bias'. Electron spin resonance measurements infer that the carbon related defects may responsible for the observed magnetic behaviour in both types of ribbons. Furthermore, proton hyperfine coupling strength has been obtained from hyperfine sublevel correlation experiments performed on the GNRs. Electron spin resonance provides no indications for the presence of potassium (cluster) related signals, emphasizing the intrinsic magnetic nature of the ribbons. Our combined experimental results may infer the coexistence of ferromagnetic clusters with anti-ferromagnetic regions leading to disordered magnetic phase. We discuss the origin of the observed contrast in the magnetic behaviours of these two types of ribbons.
The Physical Drivers and Observational Tracers of CO-to-H2 Conversion Factor Variations in Nearby Barred Galaxy Centers
Creators: name: Teng, Yu-Hsuan
name: Sandstrom, Karin M.
name: Sun, Jiayi
name: Gong, Munan
name: Bolatto, Alberto D.
name: Chiang, I-Da
name: Leroy, Adam K.
name: Usero, Antonio
name: Glover, Simon C. O.
name: Klessen, Ralf S.
name: Liu, Daizhong
name: Querejeta, Miguel
name: Schinnerer, Eva
name: Bigiel, Frank
name: Cao, Yixian
name: Chevance, Melanie
name: Eibensteiner, Cosima
name: Grasha, Kathryn
name: Israel, Frank P.
name: Murphy, Eric J.
name: Neumann, Lukas
name: Pan, Hsi-An
name: Pinna, Francesca
name: Sormani, Mattia C.
name: Smith, J. D. T.
name: Walter, Fabian
name: Williams, Thomas G.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The CO-to-H$_2$ conversion factor ($α_\rm{CO}$) is central to measuring the amount and properties of molecular gas. It is known to vary with environmental conditions, and previous studies have revealed lower $α_\rm{CO}$ in the centers of some barred galaxies on kpc scales. To unveil the physical drivers of such variations, we obtained ALMA Band 3, 6, and 7 observations toward the inner 2 kpc of NGC 3627 and NGC 4321 tracing $^{12}$CO, $^{13}$CO, and C$^{18}$O lines on 100 pc scales. Our multi-line modeling and Bayesian likelihood analysis of these datasets reveal variations of molecular gas density, temperature, optical depth, and velocity dispersion, which are among the key drivers of $α_\rm{CO}$. The central 300 pc nuclei in both galaxies show strong enhancement of temperature $T_\rm{k}>100$ K and density $n_\rm{H_2}>10^3$ cm$^{-3}$. Assuming a CO-to-H$_2$ abundance of $3\times10^{-4}$, we derive 4-15 times lower $α_\rm{CO}$ than the Galactic value across our maps, which agrees well with previous kpc-scale measurements. Combining the results with our previous work on NGC 3351, we find a strong correlation of $α_\rm{CO}$ with low-J $^{12}$CO optical depths ($τ_\rm{CO}$), as well as an anti-correlation with $T_\rm{k}$. The $τ_\rm{CO}$ correlation explains most of the $α_\rm{CO}$ variation in the three galaxy centers, whereas changes in $T_\rm{k}$ influence $α_\rm{CO}$ to second order. Overall, the observed line width and $^{12}$CO/$^{13}$CO 2-1 line ratio correlate with $τ_\rm{CO}$ variation in these centers, and thus they are useful observational indicators for $α_\rm{CO}$ variation. We also test current simulation-based $α_\rm{CO}$ prescriptions and find a systematic overprediction, which likely originates from the mismatch of gas conditions between our data and the simulations.
description: Accepted for publication in ApJ; 30 pages of main text + 3 appendices
Measurement of the magnetic penetration depth of a superconducting MgB$_{2}$ thin film with a large intraband diffusivity
Creators: name: Kim, Jeehoon
name: Haberkorn, N.
name: Lin, Shi-Zeng
name: Civale, L.
name: Nazaretski, E.
name: Moeckly, B. H.
name: Yung, C. S.
name: Thompson, J. D.
name: Movshovich, R.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We report the temperature dependent magnetic penetration depth $λ(T)$ and the superconducting critical field $H_{c2}(T)$ in a 500-nm MgB$_{2}$ film. Our analysis of the experimental results takes into account the two gap nature of the superconducting state and indicates larger intraband diffusivity in the three-dimensional (3D) $π$ band compared to that in the two-dimensional (2D) $σ$ band. Direct comparison of our results with those reported previously for single crystals indicates that larger intraband scattering in the 3D $π$ band leads to an increase of $λ$. We calculated $λ$ and the thermodynamic critical field $H_{c}\approx$2000 Oe employing the gap equations for two-band superconductors. Good agreement between the measured and calculated $λ$ value indicates the two independent measurements, such as magnetic force microscopy and transport, provide a venue for investigating superconducting properties in multi-band superconductors.
A method for filling gaps in solar irradiance and in solar proxy data
Creators: name: de Wit, T. Dudok
Publisher: name: arXiv
Year: 2011
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: Data gaps are ubiquitous in spectral irradiance data, and yet, little effort has been put into finding robust methods for filling them. We introduce a data-adaptive and nonparametric method that allows us to fill data gaps in multi-wavelength or in multichannel records. This method, which is based on the iterative singular value decomposition, uses the coherency between simultaneous measurements at different wavelengths (or between different proxies) to fill the missing data in a self-consistent way. The interpolation is improved by handling different time scales separately. Two major assets of this method are its simplicity, with few tuneable parameters, and its robustness. Two examples of missing data are given: one from solar EUV observations, and one from solar proxy data. The method is also appropriate for building a composite out of partly overlapping records.
description: to appear in Astronomy & Astrophysics (2011)
Shedding New Light on Weak Emission-Line Quasars in the C$_{\rm IV}$-H$β$ Parameter Space
Creators: name: Ha, Trung
name: Dix, Cooper
name: Matthews, Brandon M.
name: Shemmer, Ohad
name: Brotherton, Michael S.
name: Myers, Adam
name: Richards, Gordon T.
name: Maithil, Jaya
name: Anderson, Scott F.
name: Brandt, W. N.
name: Diamond-Stanic, Aleksandar M.
name: Fan, Xiaohui
name: Gallagher, Sarah C.
name: Green, Richard F.
name: Lira, Paulina
name: Luo, Bin
name: Netzer, Hagai
name: Plotkin, Richard
name: Runnoe, Jessie C.
name: Schneider, Donald P.
name: Strauss, Michael A.
name: Trakhtenbrot, Benny
name: Wu, Jianfeng
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Weak emission-line quasars (WLQs) are a subset of Type 1 quasars that exhibit extremely weak Ly$α+$N V $λ$1240 and/or C IV $λ$1549 emission lines. We investigate the relationship between emission-line properties and accretion rate for a sample of 230 `ordinary' Type 1 quasars and 18 WLQs at $z < 0.5$ and $1.5 < z < 3.5$ that have rest-frame ultraviolet and optical spectral measurements. We apply a correction to the H$β$-based black-hole mass ($M_{\rm BH}$) estimates of these quasars using the strength of the optical Fe II emission. We confirm previous findings that WLQs' $M_{\rm BH}$ values are overestimated by up to an order of magnitude using the traditional broad emission-line region size-luminosity relation. With this $M_{\rm BH}$ correction, we find a significant correlation between H$β$-based Eddington luminosity ratios and a combination of the rest-frame C IV equivalent width and C IV blueshift with respect to the systemic redshift. This correlation holds for both ordinary quasars and WLQs, which suggests that the two-dimensional C IV parameter space can serve as an indicator of accretion rate in all Type 1 quasars across a wide range of spectral properties.
description: 17 pages (AASTeX 6.3.1), 5 figures, accepted for publication in ApJ
Simulated observations of star formation regions: infrared evolution of globally collapsing clouds
Creators: name: Jáquez-Domínguez, Jesús M.
name: Galván-Madrid, Roberto
name: Fritz, Jacopo
name: Zamora-Avilés, Manuel
name: Camps, Peter
name: Bruzual, Gustavo
name: Baes, Maarten
name: Lin, Yuxin
name: Vázquez-Semadeni, Enrique
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The direct comparison between hydrodynamical simulations and observations is needed to improve the physics included in the former and test biases in the latter. Post-processing radiative transfer and synthetic observations are now the standard way to do this. We report on the first application of the \texttt{SKIRT} radiative transfer code to simulations of a star-forming cloud. The synthetic observations are then analyzed following traditional observational workflows. We find that in the early stages of the simulation, stellar radiation is inefficient in heating dust to the temperatures observed in Galactic clouds, thus the addition of an interstellar radiation field is necessary. The spectral energy distribution of the cloud settles rather quickly after $\sim3$ Myr of evolution from the onset of star formation, but its morphology continues to evolve for $\sim8$ Myr due to the expansion of \textsc{Hii} regions and the respective creation of cavities, filaments, and ridges. Modeling synthetic \textit{Herschel} fluxes with 1- or 2-component modified black bodies underestimates total dust masses by a factor of $\sim2$. Spatially-resolved fitting recovers up to about $70\%$ of the intrinsic value. This ``missing mass'' is located in a very cold dust component with temperatures below $10$ K, which does not contribute appreciably to the far-infrared flux. This effect could bias real observations if such dust exists in large amounts. Finally, we tested observational calibrations of the SFR based on infrared fluxes and concluded that they are in agreement when compared to the intrinsic SFR of the simulation averaged over $\sim100$ Myr.
Future Constraints on Dark Matter with Gravitationally Lensed Fast Radio Bursts Detected by BURSTT
Creators: name: Ho, Simon C. -C.
name: Hashimoto, Tetsuya
name: Goto, Tomotsugu
name: Lin, Yu-Wei
name: Kim, Seong Jin
name: Uno, Yuri
name: Hsiao, Tiger Y. -Y.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Understanding dark matter is one of the most urgent questions in modern physics. A very interesting candidate is primordial black holes (PBHs; Carr2016). For the mass ranges of $< 10^{-16} M_{\odot}$ and $> 100 M_{\odot}$, PBHs have been ruled out. However, they are still poorly constrained in the mass ranges of $10^{-16} - 100 M_{\odot}$ (Belotsky et al. 2019). Fast radio bursts (FRBs) are millisecond flashes of radio light of unknown origin mostly from outside the Milky Way. Due to their short timescales, gravitationally lensed FRBs, which are yet to be detected, have been proposed as a useful probe for constraining the presence of PBHs in the mass window of $< 100M_{\odot}$ (Muñoz et al. 2016). Up to now, the most successful project in finding FRBs has been CHIME. Due to its large field of view (FoV), CHIME is detecting at least 600 FRBs since 2018. However, none of them is confirmed to be gravitationally lensed (Leung et al. 2022). Taiwan plans to build a new telescope, BURSTT dedicated to detecting FRBs. Its survey area will be 25 times greater than CHIME. BURSTT can localize all of these FRBs through very-long-baseline interferometry (VLBI). We estimate the probability to find gravitationally lensed FRBs, based on the scaled redshift distribution from the latest CHIME catalog and the lensing probability function from Muñoz et al. (2016). BURSTT-2048 can detect ~ 24 lensed FRBs out of ~ 1,700 FRBs per annum. With BURSTT's ability to detect nanosecond FRBs, we can constrain PBHs to form a part of dark matter down to $10^{-4}M_{\odot}$.
description: Accepted for publication in ApJ. A summary video is available at this https://youtu.be/yivrtvuMDHE
The Utility of Affine Variables and Affine Coherent States
Creators: name: Klauder, John R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Affine coherent states are generated by affine kinematical variables much like canonical coherent states are generated by canonical kinematical variables. Although all classical and quantum formalisms normally entail canonical variables, it is shown that affine variables can serve equally well for many classical and quantum studies. This general purpose analysis provides tools to discuss two major applications: (1) the completely successful quantization of a nonrenormalizable scalar quantum field theory by affine techniques, in complete contrast to canonical techniques which only offer triviality; and (2) a formulation of the kinematical portion of quantum gravity that favors affine kinematical variables over canonical kinematical variables, and which generates a framework in which a favorable analysis of the constrained dynamical issues can take place. All this is possible because of the close connection between the affine and the canonical stories, while the few distinctions can be used to advantage when appropriate.
description: 25 pages, contribution to special J. Phys. A issue on coherent states
Characterizing quasi-steady states of fast neutrino-flavor conversion by stability and conservation laws
Creators: name: Zaizen, Masamichi
name: Nagakura, Hiroki
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The question of what ingredients characterize the quasi-steady state of fast neutrino-flavor conversion (FFC) is one of the long-standing riddles in neutrino oscillation. Addressing this issue is necessary for accurate modeling of neutrino transport in core-collapse supernova and binary neutron star merger. Recent numerical simulations of FFC have shown, however, that the quasi-steady state is sensitively dependent on boundary conditions in space, and the physical reason for the dependence is not clear at present. In this study, we provide a physical interpretation of this issue based on arguments with stability and conservation laws. The stability can be determined by the disappearance of ELN(electron neutrino-lepton number)-XLN(heavy-leptonic one) angular crossings, and we also highlight two conserved quantities characterizing the quasi-steady state of FFC: (1) lepton number conservation along each neutrino trajectory and (2) conservation law associated with angular moments, depending on boundary conditions, for each flavor of neutrinos. We present an analytic prescription that matches the results of the nonlinear simulations presented in this work. This study represents a major step forward a unified picture determining asymptotic states of FFCs.
description: 10 pages, 5 figures. Accepted in PRD
Thermal Shadows and Compositional Structure in Comet Nuclei
Creators: name: Guilbert-Lepoutre, A.
name: Jewitt, D.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We use a fully 3-dimensional thermal evolution model to examine the effects of a non-uniform surface albedo on the subsurface thermal structure of comets. Surface albedo markings cast "thermal shadows", with strong lateral thermal gradients. Corresponding compositional gradients can be strong, especially if the crystallization of amorphous water ice is triggered in the hottest regions. We show that the spatial extent of the structure depends mainly on the obliquity, ther- mal conductivity and heliocentric distance. In some circumstances, subsurface structure caused by the thermal shadows of surface features can be maintained for more than 10 Myr, the median transport time from the Kuiper Belt to the inner solar system. Non-uniform compositional structure can be an evolutionary product and does not necessarily imply that comets consist of building blocks accumulated in different regions of the protoplanetary disk.
description: Accepted in ApJ
Unveiling Pseudo-Crucial Events in Noise-Induced Phase Transitions
Creators: name: Baxley, Jacob D.
name: Lambert, David R.
name: Bologna, Mauro
name: West, Bruce J.
name: Grigolini, Paolo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Chaotic Dynamics (nlin.CD)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: Noise-induced phase transitions are common in various complex systems, from physics to biology. In this article, we investigate the emergence of crucial events in noise-induced phase transition processes and their potential significance for understanding complexity in such systems. We utilize the first-passage time technique and coordinate transformations to study the dynamics of the system and identify crucial events. Furthermore, we employ Diffusion Entropy Analysis, a powerful statistical tool, to characterize the complexity of the system and quantify the information content of the identified events. Our results show that the emergence of crucial events is closely related to the complexity of the system and can provide insight into its behavior. This approach may have applications in diverse fields, such as climate modeling, financial markets, and biological systems, where understanding the emergence of crucial events is of great importance.
Photometric and Kinematic study of the open cluster NGC 1027
Creators: name: Tripathi, Apara
name: Panwar, Neelam
name: Sharma, Saurabh
name: Kumar, Brijesh
name: Rastogi, Shantanu
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present photometric and kinematic analysis of an intermediate age open cluster NGC 1027 using $UBV(RI)_c$ and Gaia Early Data Release 3 (EDR3) data. Structural and fundamental parameters such as cluster center, cluster extent, reddening, age and distance are estimated in this study. Cluster center is found about 2 arcmin away from the center reported earlier. Radius has been estimated to be about 8.00 arcmin(2.65pc). Using proper motion Gaia EDR3 data, membership probabilities has been derived for the stars in the region of cluster radius. We find mean proper motion of the cluster to be $\sim$(-0.84, 2.04) mas yr$^{-1}$ in (RA, DEC). We find 217 most probable (P$_μ>$ 70\%) cluster members with mean parallax 0.892 $\pm$ 0.088 mas. Out of these, 160 members have counterparts in our optical observations. Few stars having P$_μ>$ 70\% are found out of the cluster radius showing imprints of dynamical evolution. The color-color and color-magnitude diagrams for the cluster members found within 8.00 arcmin have been constructed using $UBV(RI)_c$ photometry and Gaia EDR3 data. This yields a reddening E($B$-$V$) $\sim$ 0.36 mag, age $\sim$ 130 Myr and distance $\sim$ 1.14 kpc. The mass function slope in the cluster region is $Γ$ $\sim$ -1.46 $\pm$ 0.15, which is similar to other Galactic open clusters. The dynamical study shows lack of faint stars in its inner region leading to mass segregation effect. A comparison of dynamical age with cluster age indicates that NGC 1027 is a dynamically relaxed cluster suggesting that mass segregation may be imprint of its dynamical relaxation.
Aspects of the biology of Hunterella nodulosa Mackiewicz and McCrae, 1962 (Cestoidea: Caryophylidea)
Creators: name: Mudry, Dwight Robert
Publisher: name: University of Calgary
Year: 1972
Subjects: subject: QL 391 C4 M83 1972
subject: Cestoda

description: Bibliography: p. 128-138.
Opto-Mechanical Pattern Formation in Cold Atoms
Creators: name: Tesio, E.
name: Robb, G. R. M.
name: Ackemann, T.
name: Firth, W. J.
name: Oppo, G. -L.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: Transverse pattern formation in an optical cavity containing a cloud of cold two-level atoms is discussed. We show that density modulation becomes the dominant mechanism as the atomic temperature is reduced. Indeed, for low but achievable temperatures the internal degrees of freedom of the atoms can be neglected, and the system is well described by treating them as mobile dielectric particles. A linear stability analysis predicts the instability threshold and the spatial scale of the emergent pattern. Numerical simulations in one and two transverse dimensions confirm the instability and predict honeycomb and hexagonal density structures, respectively, for the blue and red detuned cases.
description: submitted to Physical Review Letters
Higher-order modulation instability and multi-Akhmediev breathers of Manakov equations: Frequency jumps over the stable gaps between the instability bands
Creators: name: Chen, Shao-Chun
name: Liu, Chong
name: Akhmediev, Nail
Publisher: name: arXiv
Year: 2023
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We study higher-order modulation instability phenomena in the frame of Manakov equations. Evolution that starts with a single pair of sidebands expands over several higher harmonics. The choice of initial pair of sidebands influences the structure of unstable frequency components and changes drastically the wave evolution leading, in some cases, to jumps across spectral components within the discrete spectrum. This complex dynamics includes several growth-decay cycles of evolution. We show this using numerical simulations of the MI process and confirm the results using the exact multi-Akhmediev breather solutions. Detailed explanation of the observed phenomena are given.
description: 9 pages, 6 figures
A New Stability Result for the Feedback Interconnection of Negative Imaginary Systems with a Pole at the Origin
Creators: name: Mabrok, Mohamed A.
name: Kallapur, Abhijit G.
name: Petersen, Ian R.
name: Lanzon, Alexander
Publisher: name: arXiv
Year: 2011
Subjects: subject: Optimization and Control (math.OC)
subject: Systems and Control (eess.SY)
subject: FOS: Mathematics
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This paper is concerned with stability conditions for the positive feedback interconnection of negative imaginary systems. A generalization of the negative imaginary lemma is derived, which remains true even if the transfer function has poles on the imaginary axis including the origin. A sufficient condition for the internal stability of a feedback interconnection for NI systems including a pole at the origin is given and an illustrative example is presented to support the result.
description: 50th IEEE Conference on Decision and Control and European Control Conference
Finding AGN remnant candidates based on radio morphology with machine learning
Creators: name: Mostert, Rafael I. J.
name: Morganti, Raffaella
name: Brienza, Marisa
name: Duncan, Kenneth J.
name: Oei, Martijn S. S. L.
name: Rottgering, Huub J. A.
name: Alegre, Lara
name: Hardcastle, Martin J.
name: Jurlin, Nika
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Remnant radio galaxies represent the dying phase of radio-loud active galactic nuclei (AGN). Large samples of remnant radio galaxies are important for quantifying the radio galaxy life cycle. The remnants of radio-loud AGN can be identified in radio sky surveys based on their spectral index, or, complementary, through visual inspection based on their radio morphology. However, this is extremely time-consuming when applied to the new large and sensitive radio surveys. Here we aim to reduce the amount of visual inspection required to find AGN remnants based on their morphology, through supervised machine learning trained on an existing sample of remnant candidates. For a dataset of 4107 radio sources, with angular sizes larger than 60 arcsec, from the LOw Frequency ARray (LOFAR) Two-Metre Sky Survey second data release (LoTSS-DR2), we started with 151 radio sources that were visually classified as 'AGN remnant candidate'. We derived a wide range of morphological features for all radio sources from their corresponding Stokes-I images: from simple source catalogue-derived properties, to clustered Haralick-features, and self-organising map (SOM) derived morphological features. We trained a random forest classifier to separate the 'AGN remnant candidates' from the not yet inspected sources. The SOM-derived features and the total to peak flux ratio of a source are shown to be most salient to the classifier. We estimate that $31\pm5\%$ of sources with positive predictions from our classifier will be labelled 'AGN remnant candidates' upon visual inspection, while we estimate the upper bound of the $95\%$ confidence interval for 'AGN remnant candidates' in the negative predictions at $8\%$. Visual inspection of just the positive predictions reduces the number of radio sources requiring visual inspection by $73\%$.
description: 23 pages; accepted for publication in A&A
Friedel Oscillation about a Friedel-Anderson Impurity
Creators: name: Tao, Yaqi
name: Bergmann, Gerd
Publisher: name: arXiv
Year: 2011
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The Friedel oscillations in the vicinity of a Friedel-Anderson (FA) impurity are investigated numerically. For an FA impurity in the local moment limit the normalized amplitude A(ξ) is S-shaped, approximately zero at short distances, approaching two at large distances and crossing the value one at the characteristic length ξ_{1/2}. Surprisingly, the Friedel oscillations of a simple non-interacting Friedel impurity with a narrow resonance at the Fermi level show a very similar behavior of their amplitude A(ξ). A comparison correlates the resonance width and the Kondo energy of the FA impurity with the characteristic length ξ_{1/2} of the Friedel oscillations.
Hydrogen-free Wolf-Rayet stars: Helium stars with envelope-inflation structure and rotation
Creators: name: Lu, Xizhen
name: Zhu, Chunhua
name: Liu, Helei
name: Guo, Sufen
name: Yu, Jinlong
name: Lü, Guoliang
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Observations have shown that the effective temperature of hydrogen-free Wolf-Rayet (WR) stars is considerably lower than that of the standard model, which means that the radius of the observed H-free WR stars is several times larger than that estimated by the standard model. The envelope inflation structure (EIS) caused by the radiation luminosity being close to the Eddington luminosity in the iron opacity peak region of H-free WR stars may be the key to resolve the radius problem of H-free WR stars. We try to explain the H-free WR stars observed in the Milk Way (MW) and the Large Magellanic Cloud (LMC) by the He stars. Using the Modules for Experiments in Stellar Astrophysics code, we compute the evolution of He stars with and without MLT++ prescriptions and discuss their effects on the EIS. We have calculated the evolution of He stars using a new mass-loss rate formula and three different relative rotational velocity and compared our results with observations on Hertzsprung-Russell diagrams. The low luminosity (log$(L/L_{\odot})\leq5.2$) H-free WR stars in the MW and the LMC can be explained by the helium giant phase in low-mass He stars, the high $X_{C}$ and $X_{O}$ in WC stars can only evolve through low-mass He stars with a rapid rotation. High-mass He stars with the EIS can explain H-free WR stars with a luminosity exceeding $10^{5.7} L_{\odot}$ and an effective temperature above $10^{4.7}$ K in the MW. They can also explain H-free WR stars on the right-hand side of the He zero-age main sequence in the LMC. High-mass stars with the EIS evolve into WO stars at the final evolution stage, and the shorter lifetime fraction is consistent with the small number of observed WO stars.
description: 9 pages, 7 figures 1 tables, Accepted to A&A
Three-player quantum Kolkata restaurant problem under decoherence
Creators: name: Ramzan, M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Effect of quantum decoherence in a three-player quantum Kolkata restaurant problem is investigated using tripartite entangled qutrit states. Amplitude damping, depolarizing, phase damping, trit-phase flip and phase flip channels are considered to analyze the behaviour of players payoffs. It is seen that Alice's payoff is heavily influenced by the amplitude damping channel as compared to the depolarizing and flipping channels. However, for higher level of decoherence, Alice's payoff is strongly affected by depolarizing noise. Whereas the behaviour of phase damping channel is symmetrical around 50 % decoherence. It is also seen that for maximum decoherence (p=1), the influence of amplitude damping channel dominates over depolarizing and flipping channels. Whereas, phase damping channel has no effect on the Alice's payoff. Therefore, the problem becomes noiseless one at maximum decoherence in case of phase damping channel. Furthermore, the Nash equilibrium of the problem does not change under decoherence.
description: 11 pages, 4 .eps figures
State revenues and democratic development : oil rents, taxation, and the need for consent
Creators: name: Wong, Judith Anne
Publisher: name: University of British Columbia
Year: 2009

description: Why do some of the world’s countries with the most abundant natural resources, in particular oil wealth, have some of the poorest records in democracy and human development? A prominent argument in the literature on this “resource curse” is that resource rents supplant tax revenues as the fiscal foundation for the state. This rentier hypothesis suggests a relationship between rent revenues, a lack of taxation and lack of democracy, but this relationship is not clearly established or explained. In this paper I develop a model of the state in which tax revenues have a positive impact on democracy because states require widespread voluntary consent in order to effectively collect tax revenues, consent which can be achieved through democratization. I argue that rents negatively affect democracy because they substitute for tax revenues, and so eliminate the necessity of securing this consent. I use time series cross sectional quantitative analysis to examine broad patterns across states and time periods. I present evidence that a substitution effect exists, with oil rents correlated with lower tax revenues, particularly in authoritarian regimes. I examine evidence that rents require lower levels of consent than tax revenues, by testing two patterns in addition to democracy. Taxation is not only more positively correlated with democracy than are rents, but also more positively correlated with higher levels of government spending and coercion.
Multiphase Gas Nature in the Sub-parsec Region of the Active Galactic Nuclei I: Dynamical Structures of Dusty and Dust-free Outflow
Creators: name: Kudoh, Yuki
name: Wada, Keiichi
name: Kawakatu, Nozomu
name: Nomura, Mariko
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We investigated dusty and dust-free gas dynamics for a radiation-driven sub-pc scale outflow in an active galactic nucleus (AGN) associated with a supermassive black hole $10^7 M_\odot$ and bolometric luminosity $10^{44}$ erg s$^{-1}$ based on the two-dimensional radiation-hydrodynamic simulations. A radiation-driven ``lotus-like'' multi-shell outflow is launched from the inner part ($r \lesssim 0.04$ pc) of the geometrically thin disk, and it repeatedly and steadily produces shocks as mass accretion continues through the disk to the center. The shape of the dust sublimation radius is not spherical and depends on the angle ($θ$) from the disk plane, reflecting the non-spherical radiation field and nonuniform dust-free gas. Moreover, we found that the sublimation radius of $θ\sim 20$-$60$ deg varies on a timescale of several years. The ``inflow-induced outflow" contributes the obscuration of the nucleus in the sub-parsec region. The column density of the dust-free gas is $N_{\rm H} \gtrsim 10^{22}$ cm$^{-2}$ for $r \lesssim 0.04$ pc. Gases near the disk plane ($θ\lesssim 30$ degree) can be the origin of the Compton-thick component, which was suggested by the recent X-ray observations of AGNs. The dusty outflow from the sub-parsec region can be also a source of material for the radiation-driven fountain for a larger scale.
description: 13 pages, 9 figures, accepted for publication in ApJ
Gap Opening in Protoplanetary Disks: Gas Dynamics from Global Non-ideal MHD Simulations with Consistent Thermochemistry
Creators: name: Hu, Xiao
name: Li, Zhi-Yun
name: Wang, Lile
name: Zhu, Zhaohuan
name: Bae, Jaehan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recent high angular resolution ALMA observations have revealed numerous gaps in protoplanetary disks. A popular interpretation has been that planets open them. Most previous investigations of planet gap-opening have concentrated on viscous disks. Here, we carry out 2D (axisymmetric) global simulations of gap opening by a planet in a wind-launching non-ideal MHD disk with consistent thermochemistry. We find a strong concentration of poloidal magnetic flux in the planet-opened gap, where the gas dynamics are magnetically dominated. The magnetic field also drives a fast (nearly sonic) meridional gas circulation in the denser disk regions near the inner and outer edges of the gap, which may be observable through high-resolution molecular line observations. The gap is more ionized than its denser surrounding regions, with a better magnetic field-matter coupling. In particular, it has a much higher abundance of molecular ion HCO$^+$, consistent with ALMA observations of the well-studied AS 209 protoplanetary disk that has prominent gaps and fast meridional motions reaching the local sound speed. Finally, we provide fitting formulae for the ambipolar and Ohmic diffusivities as a function of the disk local density, which can be used for future 3D simulations of planet gap-opening in non-ideal MHD disks where thermochemistry is too computationally expensive to evolve self-consistently with the magneto-hydrodynamics.
description: 12 pages, 13 figures, and 4 tables, accepted by MNRAS. For animated figures, see: https://www.youtube.com/watch?v=GvVPT-SOP6s&list=PLPqbg5l-CV-t-TUePtpv7VtqPL1PHP1U5&ab_channel=FloridaKeys
The Origin of Parsec-Scale Gaseous and Stellar Disks in the Galactic Center and AGNs
Creators: name: Yusef-Zadeh, F.
name: Wardle, M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The Galactic center stellar disk and the circumnuclear ring provide a unique opportunity to study in detail the dynamics and physical conditions of distant molecular disks in the nuclei of galaxies. One of the key questions is how these disks form so close to their host black holes and under what condition they form stars in a tidally stressed environment. We argue that disk formation around a massive black hole is due to partial accretion of extended molecular clouds that temporarily pass through the central region of the Galaxy. The cancellation of angular momentum of the gravitationally focused gas naturally creates a compact gaseous disk. The disk can potentially become gravitationally unstable and form stars. We apply these ideas to explain the origin of sub-parsec megamaser disks found in the nuclei of Seyfert 2 galaxies. We show that an empirical scaling relation between the mass of the black hole and the size of the disk can be understood in the context of the cloud capture scenario. We conclude that the stellar and gas disks found in our Galactic center act as a bridge to further our understanding of more distant mega-maser disks in the nuclei of Seyfert 2 galaxies.
description: 6 pages, 2 figures, to appear in "The Central Kiloparsec in Galactic Nuclei: Astronomy at High Angular Resolution 2011", open access Journal of Physics: Conference Series (JPCS), published by IOP Publishing
Aretakis Hair for Extreme Kerr Black Holes with Axisymmetric Scalar Perturbations
Creators: name: Burko, Lior M.
name: Khanna, Gaurav
name: Sabharwal, Subir
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the evolution of axially-symmetric scalar field perturbations on an extreme Kerr spacetime for initial data with multipole moments $\ell^{\prime}$ higher than the least radiative mode, and we measure modes $\ell$ -- and for the first time also horizon charges -- that are excited by mode coupling interactions. We then find the Ori-Sela prefactors, a certain quantity that can be evaluated at finite distances and the Aretakis constant along the event horizon of the extreme Kerr black hole for a sequence of initial data preparations that differ only by their distance from the event horizon. We find that for initial data in the near field there is a linear relationship of the Aretakis constant and the Ori-Sela prefactor. For initial data farther than these the linear relationship is not universal, and we propose that stronger numerical simulations would be needed to regain linearity. The linear relationship suggests that the Aretakis charge along the event horizon can be measured at a finite distance, thereby extending this type of violation of the no-hair theorems from the least radiative axisymmetric mode also to situations that involve mode coupling.
description: 8 pages, 7 figures, 5 tables
Ubiquitous equatorial accretion disc winds in black hole soft states
Creators: name: Ponti, G.
name: Fender, R. P.
name: Begelman, M. C.
name: Dunn, R. J. H.
name: Neilsen, J.
name: Coriat, M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: High resolution spectra of Galactic Black Holes (GBH) reveal the presence of highly ionised absorbers. In one GBH, accreting close to the Eddington limit for more than a decade, a powerful accretion disc wind is observed to be present in softer X-ray states and it has been suggested that it can carry away enough mass and energy to quench the radio jet. Here we report that these winds, which may have mass outflow rates of the order of the inner accretion rate or higher, are an ubiquitous component of the jet-free soft states of all GBH. We furthermore demonstrate that these winds have an equatorial geometry with opening angles of few tens of degrees, and so are only observed in sources in which the disc is inclined at a large angle to the line of sight. The decrease in Fe XXV / Fe XXVI line ratio with Compton temperature, observed in the soft state, suggests a link between higher wind ionisation and harder spectral shapes. Although the physical interaction between the wind, accretion flow and jet is still not fully understood, the mass flux and power of these winds, and their presence ubiquitously during the soft X-ray states suggests they are fundamental components of the accretion phenomenon.
description: Accepted for publication in MNRAS Letters
Comparative studies on the host-parasite interaction of Hymenolepis SPP with the hamster
Creators: name: Walder, Gordon Leroy
Publisher: name: University of Calgary
Year: 1978
Subjects: subject: QL 391 P7 W34 1978 Microfiche
subject: Cestoda
subject: Worms, Intestinal and parasitic
subject: Hamsters

description: Bibliography: p. 89-94
Quasinormal resonances of a massive scalar field in a near-extremal Kerr black hole spacetime
Creators: name: Hod, Shahar
Publisher: name: arXiv
Year: 2011
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The fundamental resonances of near-extremal Kerr black holes due to massive scalar perturbations are derived {\it analytically}. We show that there exists a critical mass parameter, $μ_c$, below which increasing the mass $μ$ of the field increases the oscillation frequency $\Re(ω)$ of the resonance. On the other hand, above the critical field mass increasing the mass $μ$ increases the damping rate $\Im(ω)$ of the mode. We confirm our analytical results by numerical computations.
description: 6 pages
High efficiency wireless power transmission at low frequency using permanent magnet coupling
Creators: name: Li, Weilai
Publisher: name: University of British Columbia
Year: 2009

description: A new method of electrical wireless power transfer has been parameterized and experimentally verified for a variety of size-scales and applications. The main distinction between this and previous methods of wireless power transfer is the nature of the coupling mechanism, which is a magnetic interaction between synchronized, rotating, permanent magnets. Its main components can be viewed as equivalent to an electric motor, a magnetic gear, and an electric generator. Its performance parameters such as power, range and efficiency are within the same order of magnitude as previously known resonant inductive power transfer devices. However, it has the distinct benefit of operating at much lower operating frequencies. A theoretical model of the new system has been developed with sufficient detail to characterize and predict experimental behavior of various sizes. The theoretical treatment has been divided into three main interactions: the motor, the generator and the magnetic gear. The mechanism for operation, as well as a model for efficiency and losses have been developed for each interaction. The viability of this new method of wireless power transfer was experimentally verified for two size-scales. The larger size-scale achieved 1.6 kW of power transfer with 15 cm separation. The main target applications of this size-scale are for wireless charging of electric vehicles and industrial applications. The smaller size-scale achieved 60 W of power transfer with 10 cm separation. The main target applications of this size-scale are for powering medical implants and consumer electronics. Both size-scales achieved efficiencies in the range of 81%, and the operating frequency did not exceed 150 Hz. The design and construction of the devices are outlined for both size-scales. Misalignment tolerance between the transmitting device and the receiver device was experimentally investigated, and related control schemes for managing the power transfer were implemented and tested. Additionally, the potential risk to human health from the time-varying magnetic field produced by this system was evaluated using exposure limits set within two widely adopted standards. For short-term exposure to the larger-scale device, the fields met the standards at a distance beyond 6 cm, and for long-term exposure, beyond 1 meter.