cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Phantom Dark Energy Models with Negative Kinetic Term
Creators: name: Kujat, Jens
name: Scherrer, Robert J.
name: Sen, A. A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We examine phantom dark energy models derived from a scalar field with a negative kinetic term for which V(phi) approaches infinity asymptotically. All such models can be divided into three classes, corresponding to an equation of state parameter w with asymptotic behavior w -> -1, w -> w_0 < -1, and w -> infinity. We derive the conditions on the potential V(phi) which lead to each of these three types of behavior. For models with w -> -1, we derive the conditions on V(phi) which determine whether or not such models produce a future big rip. Observational constraints are derived on two classes of these models: power-law potentials with V(phi) = lambda phi^alpha (with alpha positive or negative) and exponential potentials of the form V(phi) = beta e^{lambda phi^alpha}. It is shown that these models spend more time in a state with Omega_m ~ Omega_phi than do corresponding models with a constant value of w, thus providing a more satisfactory solution to the coincidence problem.
description: 9 pages, 11 figures, minor clarifications added, to appear in Phys. Rev. D
Copycat CNN: Are Random Non-Labeled Data Enough to Steal Knowledge from Black-box Models?
Creators: name: Correia-Silva, Jacson Rodrigues
name: Berriel, Rodrigo F.
name: Badue, Claudine
name: De Souza, Alberto F.
name: Oliveira-Santos, Thiago
Publisher: name: arXiv
Year: 2021
Subjects: subject: Cryptography and Security (cs.CR)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Convolutional neural networks have been successful lately enabling companies to develop neural-based products, which demand an expensive process, involving data acquisition and annotation; and model generation, usually requiring experts. With all these costs, companies are concerned about the security of their models against copies and deliver them as black-boxes accessed by APIs. Nonetheless, we argue that even black-box models still have some vulnerabilities. In a preliminary work, we presented a simple, yet powerful, method to copy black-box models by querying them with natural random images. In this work, we consolidate and extend the copycat method: (i) some constraints are waived; (ii) an extensive evaluation with several problems is performed; (iii) models are copied between different architectures; and, (iv) a deeper analysis is performed by looking at the copycat behavior. Results show that natural random images are effective to generate copycats for several problems.
description: The code is available at https://github.com/jeiks/Stealing_DL_Models
Meta-stability of the Gierer Meinhardt equations
Creators: name: Iron, David
Publisher: name: University of British Columbia
Year: 2009

description: A well-known system of partial differential equations, known as the Gierer Meinhardt system, has been used to model cellular differentiation and morphogenesis. The system is of reaction-diffusion type and involves the determination of an activator and an inhibitor concentration field. Long-lived isolated spike solutions for the activator model the localized concentration profile that is responsible for cellular differentiation. In a biological context, the Gierer Meinhardt system has been used to model such events as head determination in the hydra and heart formation in axolotl. This thesis involves a careful numerical and asymptotic analysis of this system in one dimension for a specific parameter set and a limited analysis of this system in a multidimensional setting. Numerical analysis has revealed that once the spikes form they continue to move on an extremely slow time scale. This type of phenomenon is a general indicator of meta-stable behaviour. By perturbing off of an isolated spike solution an exponentially small eigenvalue of the linearized operator was found. This small eigenvalue accounted for the extremely slow motion found numerically and thus was used to obtain an equation of motion for the location of the spike. The Gierer Meinhardt system is analyzed in the limit of small activator diffusivity for both a finite inhibitor diffusivity and for an asymptotically large inhibitor diffusivity. In this thesis, the mathematical techniques used include the method of matched asymptotic expansions, spectral theory and numerical computations.
Approximate Bayesian Neural Doppler Imaging
Creators: name: Ramos, A. Asensio
name: Baso, C. Diaz
name: Kochukhov, O.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: The non-uniform surface temperature distribution of rotating active stars is routinely mapped with the Doppler Imaging technique. Inhomogeneities in the surface produce features in high-resolution spectroscopic observations that shift in wavelength depending on their position on the visible hemisphere. The inversion problem has been systematically solved using maximum a-posteriori regularized methods assuming smoothness or maximum entropy. Our aim in this work is to solve the full Bayesian inference problem, by providing access to the posterior distribution of the surface temperature in the star. We use amortized neural posterior estimation to produce a model that approximates the high-dimensional posterior distribution for spectroscopic observations of selected spectral ranges sampled at arbitrary rotation phases. The posterior distribution is approximated with conditional normalizing flows, which are flexible, tractable and easy to sample approximations to arbitrary distributions. When conditioned on the spectroscopic observations, they provide a very efficient way of obtaining samples from the posterior distribution. The conditioning on observations is obtained through the use of Transformer encoders, which can deal with arbitrary wavelength sampling and rotation phases. Our model can produce thousands of posterior samples per second. Our validation of the model for very high signal-to-noise observations shows that it correctly approximates the posterior, although with some overestimation of the broadening. We apply the model to the moderately fast rotator II Peg, producing the first Bayesian map of its temperature inhomogenities. We conclude that conditional normalizing flows are a very promising tool to carry out approximate Bayesian inference in more complex problems in stellar physics, like constraining the magnetic properties.
description: 14 pages, 10 figures, submitted to A&A
Criticality of spreading dynamics in hierarchical cluster networks without inhibition
Creators: name: Kaiser, Marcus
name: Goerner, Matthias
name: Hilgetag, Claus C.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: Physics and Society (physics.soc-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: An essential requirement for the representation of functional patterns in complex neural networks, such as the mammalian cerebral cortex, is the existence of stable network activations within a limited critical range. In this range, the activity of neural populations in the network persists between the extremes of quickly dying out, or activating the whole network. The nerve fiber network of the mammalian cerebral cortex possesses a modular organization extending across several levels of organization. Using a basic spreading model without inhibition, we investigated how functional activations of nodes propagate through such a hierarchically clustered network. The simulations demonstrated that persistent and scalable activation could be produced in clustered networks, but not in random networks of the same size. Moreover, the parameter range yielding critical activations was substantially larger in hierarchical cluster networks than in small-world networks of the same size. These findings indicate that a hierarchical cluster architecture may provide the structural basis for the stable and diverse functional patterns observed in cortical networks.
Letter from G. Bryan Williams, Provincial Game Warden, to the Manager of Rainbow Ranche, November 21, 1910
Creators: name: Williams, G. Bryan
Publisher: name: The University of British Columbia
Year: 2017

description: Letter to the Manager of Rainbow Ranche from G. Bryan Williams, Provincial Game  Warden, dated November 21, 1910, regarding a complaint about prairie chicken damaging the Ranche's orchard.
Abrupt transition due to non-local cascade propagation in multiplex systems
Creators: name: Artime, Oriol
name: De Domenico, Manlio
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Multilayer systems are coupled networks characterized by different contexts (layers) of interaction and have gained much attention recently due to their suitability to describe a broad spectrum of empirical complex systems. They are very fragile to percolation and first-neighbor failure propagation, but little is known about how they respond to non-local disruptions, as it occurs in failures induced by flow redistribution, for example. Acknowledging that many socio-technical and biological systems sustain a flow of some physical quantity, such as energy or information, across the their components, it becomes crucial to understand when the flow redistribution can cause global cascades of failures in order to design robust systems,to increase their resilience or to learn how to efficiently dismantle them. In this paper we study the impact that different multiplex topological features have on the robustness of the system when subjected to non-local cascade propagation. We first numerically demonstrate that this dynamics has a critical value at which a small initial perturbation effectively dismantles the entire network, and that the transition appears abruptly. Then we identify that the excess of flow caused by a failure is, in general, more homogeneously distributed the networks in which the average distance between nodes is small.Using this information we find that aggregated versions of multiplex networks tend to overestimate robustness, even though to make the system more robust can be achieved by increasing the number of layers. Our predictions are confirmed by simulated cascading failures in areal multilayer system.
Stochastic effects on biodiversity in cyclic coevolutionary dynamics
Creators: name: Reichenbach, Tobias
name: Mobilia, Mauro
name: Frey, Erwin
Publisher: name: arXiv
Year: 2006
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Finite-size fluctuations arising in the dynamics of competing populations may have dramatic influence on their fate. As an example, in this article, we investigate a model of three species which dominate each other in a cyclic manner. Although the deterministic approach predicts (neutrally) stable coexistence of all species, for any finite population size, the intrinsic stochasticity unavoidably causes the eventual extinction of two of them.
description: 5 pages, 2 figures. Proceedings paper of the workshop "Stochastic models in biological sciences" (May 29 - June 2, 2006 in Warsaw) for the Banach Center Publications
Hubble Space Telescope Observations of NGC 253 Dwarf Satellites: Discovery of Three Ultra-faint Dwarf Galaxies
Creators: name: Mutlu-Pakdil, Burçin
name: Sand, David J.
name: Crnojević, Denija
name: Jones, Michael G.
name: Caldwell, Nelson
name: Guhathakurta, Puragra
name: Seth, Anil C.
name: Simon, Joshua D.
name: Spekkens, Kristine
name: Strader, Jay
name: Toloba, Elisa
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present deep Hubble Space Telescope imaging of five faint dwarf galaxies associated with the nearby spiral NGC 253 (D$\approx$3.5 Mpc). Three of these are newly discovered ultra-faint dwarf galaxies, while all five were found in the Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS), a Magellan$+$Megacam survey to identify faint dwarfs and other substructures in resolved stellar light around massive galaxies outside of the Local Group. Our HST data reach $\gtrsim$3 magnitudes below the tip of the red giant branch for each dwarf, allowing us to derive their distances, structural parameters, and luminosities. All five systems contain predominantly old, metal-poor stellar populations (age$\sim$12 Gyr, [M/H]$\lesssim$$-$1.5) and have sizes ($r_{h}$$\sim$110-3000 pc) and luminosities ($M_V$$\sim$$-7$ to $-12$ mag) largely consistent with Local Group dwarfs. The three new NGC 253 satellites are among the faintest systems discovered beyond the Local Group. We also use archival HI data to place limits on the gas content of our discoveries. Deep imaging surveys such as our program around NGC 253 promise to elucidate the faint end of the satellite luminosity function and its scatter across a range of galaxy masses, morphologies, and environments in the decade to come.
description: 11 pages, 4 figures, 1 table; submitted to ApJL; comments welcome
A Study of the Time Variability and Line Profile Variations of kappa Dra
Creators: name: Saad, S. M.
name: Nouh, M. I.
name: Shokry, A.
name: Zead, I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: In this study, we present a spectroscopic analysis of the bright Be star kappa Dra. Two independent sets of radial velocity velocities (RV) measurements were obtained by direct measurement and using a line profile disentangling technique. Using a combination of the solutions found by the codes FOTEL and KOREL, we revisited the binary nature of kappa Dra and derived improved orbital elements. From the RVs of the Balmer lines and also from some strong metallic lines we found that all RVs variations are phase-locked with the orbital period. V/R variations were obtained for H_alpha, H_beta, H_gamma and some other photospheric lines and they are found to be phase-locked with the orbital motion. A moving absorption bump superimposed over the H_alpha and H_beta emission line profiles was detected. The orbital solutions for kappa Dra were derived assuming a circular orbit with a period 61.5549 day and K = 6.81 km/s . The question of the line profile variability was discussed. We attempted to search for absorption or emission lines of the unresolved secondary component, we failed to find them.
Dolichogenidea credne
Creators: name: Fernandez-Triana, Jose
name: Sakagami, Kota
name: Shimizu, So
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Braconidae
Dolichogenidea
Dolichogenidea credne

description: D. credne (Nixon, 1973): Antenna short, with flagellomeres 14 and 15 cubic; pterostigma brown; propodeum mostly polished and without areola (only small rugae above nucha); T1 narrowing towards posterior margin; T2 subtriangular (trapezoidal).
description: Published as part of Fernandez-Triana, Jose, Sakagami, Kota & Shimizu, So, 2018, Dolichogenidea maetoi sp. nov. (Hymenoptera: Braconidae) from Japan, the first parasitoid wasp recorded from Hyblaea fortissima (Lepidoptera), pp. 167-175 in Acta Entomologica Musei Nationalis Pragae 58 (1) on page 171, DOI: 10.2478/aemnp-2018-0014, http://zenodo.org/record/3699178
Helium-like ions in $d$-dimensions: analyticity and generalized ground state Majorana solutions
Creators: name: Escobar-Ruiz, Adrian M.
name: Olivares-Pilón, Horacio
name: Aquino, Norberto
name: Cruz, Salvador A.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Non-relativistic Helium-like ions $(-e,-e,Ze)$ with static nucleus in a $d-$dimensional space $\mathbb{R}^d$ ($d>1$) are considered. Assuming $r^{-1}$ Coulomb interactions, a 2-parametric correlated Hylleraas-type trial function is used to calculate the ground state energy of the system in the domain $Z \leq 10$. For odd $d=3,5$, the variational energy is given by a rational algebraic function of the variational parameters whilst for even $d=2,4$ it is shown for the first time that it corresponds to a more complicated non-algebraic expression. This twofold analyticity will hold for any $d$. It allows us to construct reasonably accurate approximate solutions for the ground state energy $E_0(Z,d)$ in the form of compact analytical expressions. We call them generalized Majorana solutions. They reproduce the first leading terms in the celebrated $\frac{1}{Z}$ expansion, and serve as generating functions for certain correlation-dependent properties. The (first) critical charge $Z_{\rm c}$ vs $d$ and the Shannon entropy $S_{r}^{(d)}$ vs $Z$ are also calculated within the present variational approach. In the light of these results, for the physically important case $d=3$ a more general 3-parametric correlated Hylleraas-type trial is used to compute the finite mass effects in the Majorana solution for a three-body Coulomb system with arbitrary charges and masses. It admits a straightforward generalization to any $d$ as well. Concrete results for the systems $e^-\,e^-\,e^+$, $H_2^+$ and $H^-$ are indicated explicitly. Our variational analytical results are in excellent agreement with the exact numerical values reported in the literature.
description: 30 pages, 6 figures
The signature of 44Ti in Cassiopeia A revealed by IBIS/ISGRI on INTEGRAL
Creators: name: Renaud, M.
name: Vink, J.
name: Decourchelle, A.
name: Lebrun, F.
name: Hartog, P. R. den
name: Terrier, R.
name: Couvreur, C.
name: Knodlseder, J.
name: Martin, P.
name: Prantzos, N.
name: Bykov, A. M.
name: Bloemen, H.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We report the detection of both the 67.9 and 78.4 keV 44Sc gamma-ray lines in Cassiopeia A with the INTEGRAL IBIS/ISGRI instrument. Besides the robustness provided by spectro-imaging observations, the main improvements compared to previous measurements are a clear separation of the two 44Sc lines together with an improved significance of the detection of the hard X-ray continuum up to 100 keV. These allow us to refine the determination of the 44Ti yield and to constrain the nature of the nonthermal continuum emission. By combining COMPTEL, BeppoSAX/PDS and ISGRI measurements, we find a line flux of (2.5 +/- 0.3)*10(-5) cm(-2) s(-1) leading to a synthesized 44Ti mass of 1.6 (+0.6-0.3)*10(-4) solar mass. This high value suggests that Cas A is peculiar in comparison to other young supernova remnants, from which so far no line emission from 44Ti decay has been unambiguously detected.
description: 5 pages, 4 figures, Accepted for publication in ApJL
Further excavations at Fin Cop and stable isotope analysis of the skeletons
Creators: name: Waddington, Clive
name: Montgomery, Janet
Publisher: name: Archaeology Data Service
Year: 2021

description: The Derbyshire Archaeological Journal, 137, 22-65
description: The main results and discussion of the Fin Cop investigations has been published elsewhere (Waddington 2012). This paper presents the results from a further excavation trench (Trench 9) cut across the southeast corner of the rampart during the summers of 2012 and 2014 by Archaeological Research Services Ltd with the help of local volunteers and, for the 2012 season only, with the assistance of Cranfi eld University as part of their student fi eldwork training. The trench was extended by 2m in a southerly direction during the 2014 season. The excavation followed directly on from the investigations undertaken by Archaeological Research Services Ltd and the Longstone Local History Group during 2009 and 2010. The partial remains of at least 6 human individuals comprising two adults, one perinate and three neonates were identifi ed in the rampart destruction deposit within the fi ll of the hillfort ditch in Trench 9. Small fragments of animal bone were also found in the hillfort ditch and within the stone wall core comprising remains of cattle, sheep/goat, rabbit/hare and a possible rat. Botanical macrofossils and charred wood were also present, together with a few small pottery fragments and a small assemblage of residual chipped stone tools resulting from Stone Age activity on the site. Strontium, oxygen, carbon and nitrogen isotope analysis was undertaken on teeth and bone from four adults, a juvenile, two infants and fi ve peri/neonates that were retrieved from the various excavation campaigns. The carbon and nitrogen isotopes of the adults indicate a mixed diet of terrestrial C3 plants and animal protein which is in line with contemporaneous Iron Age populations in Britain. More variation was observed in the sub-adults which may be related to breastfeeding or prenatal stress. Strontium and oxygen isotopes of fi ve of the individuals indicate that only one adult was consistent with origins on the limestone of the White Peak and three individuals were consistent with sedimentary regions within 20 miles. One adult female has an unusually high strontium isotope ratio which is indicative of origins in a granitic terrain.
Electro-optically controlled divided-pulse amplification
Creators: name: Stark, Henning
name: Müller, Michael
name: Kienel, Marco
name: Klenke, Arno
name: Limpert, Jens
name: Tünnermann, Andreas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A novel technique for divided-pulse amplification is presented in a proof-of-principle experiment. A pulse burst, cut out of the pulse train of a mode-locked oscillator, is amplified and temporally combined into a single pulse. High combination efficiency and excellent pulse contrast are demonstrated. The system is mostly fiber-coupled, enabling a high interferometric stability. This approach provides access to the amplitude and phase of the individual pulses in the burst to be amplified, potentially allowing the compensation of gain saturation and nonlinear phase mismatches within the burst. Therefore, this technique enables the scaling of the peak power and pulse energy of pulsed laser systems beyond currently prevailing limitations.
Optical Surface Brightness Fluctuations of shell galaxies towards 100 Mpc
Creators: name: Biscardi, I.
name: Raimondo, G.
name: Cantiello, M.
name: Brocato, E.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We measure F814W Surface Brightness Fluctuations (SBF) for a sample of distant shell galaxies with radial velocities ranging from 4000 to 8000 km/s. The distance at galaxies is then evaluated by using the SBF method. For this purpose, theoretical SBF magnitudes for the ACS@HST filters are computed for single burst stellar populations covering a wide range of ages (t=1.5-14 Gyr) and metallicities (Z=0.008-0.04). Using these stellar population models we provide the first $\bar{M}_{F814W}$ versus $(F475W-F814W)_0$ calibration and we extend the previous I-band versus $(B-I)_0$ color relation to colors $(B-I)_{0}\leq 2.0$ mag. Coupling our SBF measurements with the theoretical calibration we derive distances with a statistical uncertainty of $\sim 8%$, and systematic error of $\sim 6 %$. The procedure developed to analyze data ensures that the indetermination due to possible unmasked residual shells is well below $\sim 12 %$. The results suggest that \emph{optical} SBFs can be measured at $d \geq 100 Mpc$ with ACS@HST imaging. SBF-based distances coupled with recession velocities corrected for peculiar motion, allow us obtain $H_{0} = 76 \pm 6$ (statistical) $\pm 5$ (systematic) km/s/Mpc.
description: 29 pages, 7 figures, 5 tables. Accepted for Publication in ApJ
Degradation of phonons in disordered moiré superlattices
Creators: name: Ochoa, Héctor
name: Fernandes, Rafael M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The elastic collective modes of a moiré superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called phasons, are not protected by any conservation law. Here, we show that disorder in the relative orientation between the layers and thermal fluctuations associated with their sliding motion degrade the propagation of sound in the moiré superlattice. Specifically, the phason modes become overdamped at low energies and acquire a finite gap, which displays a universal dependence on the twist-angle variance. Thus, twist-angle inhomogeneity is manifested not only in the non-interacting electronic structure of moiré systems, but also in their phonon-like modes. More broadly, our results have important implications for the electronic properties of twisted moiré systems that are sensitive to the electron-phonon coupling.
description: 5 pages, 2 figures + Supplemental Material
Cosmic Ray Scattering in Compressible Turbulence
Creators: name: Lazarian, Alex
name: Beresnyak, Andrey
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We study the scattering of low-energy Cosmic Rays (CRs) in a turbulent, compressive MHD fluid. We show that compressible MHD modes -- fast or slow waves with wave lengths smaller than CR mean free paths induce cyclotron instability in CRs. The instability feeds the new small-scale Alfvenic wave component with wave vectors mostly along magnetic field, which is not a part of the MHD turbulence cascade. This new component gives feedback on the instability through decreasing the CR mean free path. We show that the ambient turbulence fully suppresses the instability at large scales, while wave steepening constrains the amplitude of the waves at small scales. We provide the energy spectrum of the plane-parallel Alfvenic component and calculate mean free paths of CRs as a function of their energy. We find that for the typical parameters of turbulence in the interstellar medium and in the intercluster medium the new Alfvenic component provides the scattering of the low energy CRs that exceeds the direct resonance scattering by MHD modes. This solves the problem of insufficient scattering of low-energy CRs in the turbulent interstellar or intracluster medium that was reported in the literature.
description: 9 pages, 2 figures, a new section, accepted to MNRAS
Noncommutative Classical and Quantum Mechanics for Quadratic Lagrangians (Hamiltonians)
Creators: name: Dragovich, Branko
name: Rakic, Zoran
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider classical and quantum mechanics for an extended Heisenberg algebra with additional canonical commutation relations for position and momentum coordinates. In our approach this additional noncommutativity is removed from the algebra by linear transformation of coordinates and transmitted to the Hamiltonian (Lagrangian). Since linear transformations do not change the quadratic form of Hamiltonian (Lagrangian), and Feynman's path integral has well-known exact expression for quadratic models, we restricted our analysis to this class of physical systems. The compact general formalism presented here can be easily realized in any particular quadratic case. As an important example of phenomenological interest, we explored model of a charged particle in the noncommutative plane with perpendicular magnetic field. We also introduced an effective Planck constant $\hbar_{eff}$ which depends on noncommutativity.
description: 16 pages
Some consequences of a Higgs triplet
Creators: name: Dey, Paramita
name: Kundu, Anirban
name: Mukhopadhyaya, Biswarup
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider an extension of the scalar sector of the Standard Model with a single complex Higgs triplet $X$. Such extensions are the most economic, model-independent way of generating neutrino masses through triplet interactions. We show that a term like $\azeroΦΦX^†$ must be included in the most general potential of such a scenario, in order to avoid a massless neutral physical scalar. We also demonstrate that $\azero$ must be real, thus ruling out any additional source of CP-violation. We then examine the implications of this term in the mass matrices of the singly-and doubly-charged scalar, neutral scalar and pseudoscalar fields. We find that, for small values of $\azero/\vtwo$, where $\vtwo$ is the triplet vev, the spectrum allows the decay of heavier scalars into lighter ones via gauge interactions. For large $\azero/\vtwo$, the doubly-charged, singly-charged and neutral pseudoscalar bosons become practically degenerate, while the even-parity neutral scalars remain considerably lighter, thus emphasizing the possibility of decay of the singly-charged or neutral pseudoscalar states into the neutral scalars. Constraints from the $ρ$-parameter are used to find nontrivial limits on the charged Higgs mass depending on $\azero$. We also study the couplings of the various physical states in this scenario. For small values of $|\azero|/\vtwo$, we find the lightest neutral scalar field to be triplet-dominated, and thus having extremely suppressed interactions with fermion as well as gauge boson pairs.
description: Revised version, 25 pages, 4 figures
Mobility edge of Stark many-body localization
Creators: name: Zhang, Li
name: Ke, Yongguan
name: Liu, Wenjie
name: Lee, Chaohong
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate many-body localization of interacting spinless fermions in a one-dimensional disordered and tilted lattice. The fermions undergo energy-dependent transitions from ergodic to Stark many-body localization driven by the tilted potential, which are manifested by the appearance of mobility edges between delocalized states and Stark many-body localized states even when the disorder is weak. We can concretely diagnose these transitions rather than crossovers by finite-size scaling of energy-level statistics. Moreover, in the Stark many-body localization, the entanglement entropy obeys the area law scaling, in analogy to that in the conventional many-body localization.
Bar Brook mills: the transition from smelt mill to slag mill
Creators: name: Goodinson, Andrea
Publisher: name: Archaeology Data Service
Year: 2021

description: The Derbyshire Archaeological Journal, 137, 175-197
description: This report summarises a central component of research undertaken for a recent master's thesis. The research examines the 17th-19th century Bar Brook lead mills near Baslow, Derbyshire. Using existing survey plans, measured survey, archival research and published sources a clearer insight into function and chronology of the mills materialised. The results demonstrate current scheduling complexity, signifi cant earthworks and structures while highlighting signifi cant survey work by the late L. H. Butcher. The chronology presents a smelt mill (Site 1), followed by a slag mill (Site 2) with a related cupola; a corn mill and pumping station later adopting the area of Site 1, following the slag mill transition downstream. The study recommends that scheduling is clarifi ed and extended to include Site 1, and the work of L. H. Butcher is digitised fully to aid future research. Further research is also recommended to support the chronology and determine the environmental and landscape impacts.
Statistics of relativistically broadened Fe K-alpha lines in AGN
Creators: name: Guainazzi, M.
name: Bianchi, S.
name: Dovciak, M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present preliminary results on the properties of relativistically broadened Fe K-alpha lines in a collection of more then 100 Active Galactic Nuclei (AGN) observed by the XMM-Newton EPIC-pn camera. Our main conclusions can be summarized as follows: a) we detect broad lines in about 25% of the sample objects. This fraction increases to 42+/-13% if we consider only objects with more than 10000 counts in the hard (2-10 keV) band, and to 50+/-32% for the small sub-sample (6 objects) of type~1 Piccinotti AGN with optimal XMM-Newton exposure (at least 200000 counts in the hard band); b) we find no significant difference in the detection rate of broad lines between obscured and unobscured AGN; c) the strongest relativistic profiles are measured in low-luminosity (< 10^43 erg/s) AGN; d) Equivalent Widths (EWs) associated with relativistic profiles in stacked spectra are ~150 eV for all luminosity classes; e) models of relativistically broadened iron line profiles ("kyrline", Dovciak et al. 2005), which include full relativistic treatment of the accretion disk emission around a Kerr black hole in the strong gravity regime, yield an average disk inclination angle ~30 degrees, and a radial dependence of the disk emissivity profile ~-3. The distribution of EW is very broad, with =2.4. We estimate that an investment of about 1 Ms of XMM-Newton time would be required to put these results on a sound statistical basis.
description: 4 pages, 9 figures, to appear in Astronomische Nachrichten, Proceedings of the ESAC Workshop "Variable and broad lines around black holes"
Dynamical magneto-electric coupling in helical magnets
Creators: name: Katsura, Hosho
name: Balatsky, Alexander V.
name: Nagaosa, Naoto
Publisher: name: arXiv
Year: 2006
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Collective mode dynamics of the helical magnets coupled to electric polarization via spin-orbit interaction is studied theoretically. The soft modes associated with the ferroelectricity are not the transverse optical phonons, as expected from the Lyddane-Sachs-Teller relation, but are the spin waves hybridized with the electric polarization. This leads to the Drude-like dielectric function $ε(ω)$ in the limit of zero magnetic anisotropy. There are two more low-lying modes; phason of the spiral and rotation of helical plane along the polarization axis. The roles of these soft modes in the neutron scattering and antiferromagnetic resonance are revealed, and a novel experiment to detect the dynamical magneto-electric coupling is proposed.
description: 5 pages, 1 figure
Cryptocurrency portfolio optimization with multivariate normal tempered stable processes and Foster-Hart risk
Creators: name: Kurosaki, Tetsuo
name: Kim, Young Shin
Publisher: name: arXiv
Year: 2020
Subjects: subject: Portfolio Management (q-fin.PM)
subject: FOS: Economics and business

description: We study portfolio optimization of four major cryptocurrencies. Our time series model is a generalized autoregressive conditional heteroscedasticity (GARCH) model with multivariate normal tempered stable (MNTS) distributed residuals used to capture the non-Gaussian cryptocurrency return dynamics. Based on the time series model, we optimize the portfolio in terms of Foster-Hart risk. Those sophisticated techniques are not yet documented in the context of cryptocurrency. Statistical tests suggest that the MNTS distributed GARCH model fits better with cryptocurrency returns than the competing GARCH-type models. We find that Foster-Hart optimization yields a more profitable portfolio with better risk-return balance than the prevailing approach.
description: 15 pages, 5 tables, 1 figure
title: Deep Learning bei Nutzerbewertungen von Spielen
title: Vorhersage der Bewertung auf Basis des Texts einer Benutzerbewertung
titleType: Subtitle
Creators: name: Hofer, Julian
Publisher: name: FH CAMPUS 02 (CAMPUS 02 Fachhochschule der Wirtschaft)
Year: 2025
Subjects: subject: 006 Spezielle Computerverfahren

description: Diese Arbeit beschäftigt sich damit wie Deep Neural Networks (DNN) genutzt werden können, um Videospielbewertungen auf Basis eines von Benutzer*innen geschriebenen Textes, einen Score zuzuweisen. Da es sich hierbei um von Endbenutzer*innen verfasste Bewertungen handelt, müssen für diese Arbeit einerseits Maßnahmen auf Basis von schlechter Rechtschreibung und Grammatik getroffen werden, andererseits auch derzeitige Trends wie das Review Bombing berücksichtigt werden. Um dies zu bewerkstelligen, wurde CRISP-DM als Vorgehensmodell gewählt, um die Texte mit den jeweiligen Scores zu analysieren. Ein Webcrawler wurde verwendet um Nutzerwertungen mit Text und Score von der Seite metacritic.com zu extrahieren. Diese Daten wurden dann basierend auf mehreren Faktoren gefiltert und in Trainings-, Validierungs- und Testdatensatz aufgeteilt. Alles in allem wurden insgesamt 420.000 Bewertungen für das Trainieren, Validieren und Testen der Modelle verwendet. Zwei unterschiedliche Arten von neuronalen Netzen wurden trainiert: Long-Short-Term-Memory (LSTM) und Transformer. Beide Netzwerke wurden mit leicht unterschiedlichen Testdatensätzen auf verschiedenste Parameter verglichen. Die Ergebnisse zeigen, dass Transformer LSTMs in verschiedensten Metriken entweder leicht oder sogar mit großer Signifikanz übertreffen. Weiters sind Transformer sehr viel einfacher Hardware-optimal zu trainieren, da sie für Parallelisierung konzipiert sind, was sich in den Trainingszeiten widerspiegelt.
description: This thesis explores the ways in which deep neural networks (DNN) can be used to assign video game reviews a score based on the written text provided by the user. Since this involves user-written video game reviews, additional challenges must also be addressed, such as bad writing and grammar, as well as issues with proper categorization due to the recent trends such as review bombing. To accomplish this, I first use CRISP-DM to analyze the data given in video game reviews with a score. A crawler was used to scrape user reviews from metacritic.com that have a text and a score attached to them. This data was then filtered for several factors to have a clean training, validation and test set for model training. In total, about 420,000 written reviews were used for training, validation or testing. Two different types of DNN were then trained and compared: Long- Short- Term Memory Networks (LSTM) and Transformers. These networks were then compared to each other with different test data sets based. The results show that Transformers outperform LSTMs in different parameters by slight to significant margins. Furthermore, Transformers were the easiest model to train and offer the option for fast iteration in training.
Analysis and computation of immersed boundaries, with application to pulp fibres
Creators: name: Stockie, John Michael
Publisher: name: University of British Columbia
Year: 2009

description: Immersed fibres are a very useful tool for modeling moving, elastic interfaces that interact with a surrounding fluid. The Immersed Boundary Method is a computational tool based on the immersed fibre model which has been used successfully to study a wide range of applications including blood flow in the heart and arteries and motion of suspended particles. This work centres around a linear analysis of an isolated fibre in two dimensions, which pinpoints a discrete set of solution modes associated solely with the fibre. We investigate the stability and stiffness characteristics of the fibre modes and then relate the results to the severe time step restrictions experienced in explicit and semi-implicit immersed boundary computations. A subset of the modes corresponding to tangential oscillations of the fibre are the main source of stiffness, which intensifies when the fibre force is increased or fluid viscosity is decreased — this explains why computations are limited to unrealistically small Reynolds numbers. We also investigate the effects of smoothing the fibre over a given thickness, which corresponds to the delta function approximation that is central to the discrete scheme. The results can be applied to explore the accuracy of various interpolation methods in an idealised setting. The analysis is next extended to predict time step restrictions and convergence rates for various explicit and semi-implicit discretisations. The results are verified in numerical experiments. Finally, we introduce a novel application of the Immersed Boundary Method to the motion of pulp fibres in a two-dimensional shear flow. The method is shown to reproduce both theoretical results and experimentally observed behaviour over a wide range of parameter values.
A prehistoric pit with possible burial at Hollins Cross, Hope Valley
Creators: name: Hall, Ann
name: Waddington, Clive
name: Wilson, Arthur
Publisher: name: Archaeology Data Service
Year: 2021

description: The Derbyshire Archaeological Journal, 138, 1-13
description: The chance discovery of a burnt discoidal scraper by the path at Hollins Cross led to a small archaeological investigation of the immediately surrounding area of ground. The fl int was on the surface of a small, heavily truncated pit which was later excavated and found to be fi lled almost entirely with burnt organic material. Three other chipped stone tools along with two very rare, fi red clay disc beads, one grain of wheat, burnt hazelnut shells, four tiny fragments of bone and 163 very small fl akes of fl int were also present. Radiocarbon dating of two hazelnut shell fragments has dated the fi ll of the pit to around the 20th century cal BC. Isolated pits dating from this period are rare and this pit was situated within an eroded and much reduced earthen mound the remnants of which can still be seen on the site. The presence of tiny burnt bone fragments and perforated clay beads suggests the pit is the basal remains of a heavily truncated secondary grave pit inserted into the mound, and possibly that of a woman.
A discrete version of Liouville’s theorem on conformal maps
Creators: name: Pinkall, Ulrich
name: Springborn, Boris
Publisher: name: Technische Universität Berlin
Year: 2021
Subjects: subject: 510 Mathematik
subject: conformal flatness
subject: discrete conformal map
subject: Möbius transformation

description: Liouville’s theorem says that in dimension greater than two, all conformal maps are Möbius transformations. We prove an analogous statement about simplicial complexes, where two simplicial complexes are considered discretely conformally equivalent if they are combinatorially equivalent and the lengths of corresponding edges are related by scale factors associated with the vertices.
Ultra high energy neutrino-nucleon cross section from cosmic ray experiments and neutrino telescopes
Creators: name: Barger, V.
name: Huber, Patrick
name: Marfatia, Danny
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Astrophysics (astro-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We deduce the cosmogenic neutrino flux by jointly analysing ultra high energy cosmic ray data from HiRes-I and II, AGASA and the Pierre Auger Observatory. We make two determinations of the neutrino flux by using a model-dependent method and a model-independent method. The former is well-known, and involves the use of a power-law injection spectrum. The latter is a regularized unfolding procedure. We then use neutrino flux bounds obtained by the RICE experiment to constrain the neutrino-nucleon inelastic cross section at energies inaccessible at colliders. The cross section bounds obtained using the cosmogenic fluxes derived by unfolding are the most model-independent bounds to date.
description: 20 pages, 6 figures, 2 tables
Developmental time windows for spatial growth generate multiple-cluster small-world networks
Creators: name: Nisbach, Florian
name: Kaiser, Marcus
Publisher: name: arXiv
Year: 2008
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Neurons and Cognition (q-bio.NC)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Many networks extent in space, may it be metric (e.g. geographic) or non-metric (ordinal). Spatial network growth, which depends on the distance between nodes, can generate a wide range of topologies from small-world to linear scale-free networks. However, networks often lacked multiple clusters or communities. Multiple clusters can be generated, however, if there are time windows during development. Time windows ensure that regions of the network develop connections at different points in time. This novel approach could generate small-world but not scale-free networks. The resulting topology depended critically on the overlap of time windows as well as on the position of pioneer nodes.
Shallow Valence Band of Rutile GeO$_2$ and P-type Doping
Creators: name: Niedermeier, Christian A.
name: Ide, Keisuke
name: Katase, Takayoshi
name: Hosono, Hideo
name: Kamiya, Toshio
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: GeO$_2$ has an $α$-quartz-type crystal structure with a very wide fundamental band gap of 6.6 eV and is a good insulator. Here we find that the stable rutile-GeO$_2$ polymorph with a 4.6 eV band gap has a surprisingly low $\sim$6.8 eV ionization potential, as predicted from the band alignment using first-principles calculations. Because of the short O$-$O distances in the rutile structure containing cations of small effective ionic radii such as Ge$^{4+}$, the antibonding interaction between O 2p orbitals raises the valence band maximum energy level to an extent that hole doping appears feasible. Experimentally, we report the flux growth of $1.5 \times 1.0 \times 0.8$ mm$^3$ large rutile GeO$_2$ single crystals and confirm the thermal stability for temperatures up to $1021 \pm 10~^\circ$C. X-ray fluorescence spectroscopy shows the inclusion of unintentional Mo impurities from the Li$_2$O$-$MoO$_3$ flux, as well as the solubility of Ga in the r-GeO$_2$ lattice as a prospective acceptor dopant. The resistance of the Ga- and Mo-codoped r-GeO$_2$ single crystals is very high at room temperature, but it decreases by 2-3 orders of magnitude upon heating to 300 $^\circ$C, which is attributed to thermally-activated p-type conduction.
Multitype randomized Reed--Frost epidemics and epidemics upon random graphs
Creators: name: Neal, Peter
Publisher: name: arXiv
Year: 2006
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 92D30 (Primary) 05C80 (Secondary)

description: We consider a multitype epidemic model which is a natural extension of the randomized Reed--Frost epidemic model. The main result is the derivation of an asymptotic Gaussian limit theorem for the final size of the epidemic. The method of proof is simpler, and more direct, than is used for similar results elsewhere in the epidemics literature. In particular, the results are specialized to epidemics upon extensions of the Bernoulli random graph.
description: Published at http://dx.doi.org/10.1214/105051606000000123 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)