cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Discovery of a 0.02 Hz QPO feature in the Transient X-ray Pulsar KS 1947+300
Creators: name: James, Marykutty
name: Paul, Biswajit
name: Devasia, Jincy
name: Indulekha, Kavila
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report the discovery of Quasi Periodic Oscillations (QPO) at 0.02 Hz in a transient high mass X-ray binary pulsar KS 1947+300 using {\em RXTE}-PCA. The QPOs were detected during May-June 2001, at the end of a long outburst. This is the 9th transient accretion powered high magnetic field X-ray pulsar in which QPOs have been detected and the QPO frequency of this source is lowest in this class of sources. The unusual feature of this source is that though the outburst lasted for more than 100 days, the QPOs were detected only during the last few days of the outburst when the X-ray intensity had decayed to 1.6% of the peak intensity. The rms value of the QPO is large, $\sim15.4\pm1.0%$ with a slight positive correlation with energy. The detection of QPOs and strong pulsations at a low luminosity level suggests that the magnetic field strength of the neutron star is not as high as was predicted earlier on the basis of a correlation between the spin-up torque and the X-ray luminosity.
description: Accepted in MNRAS
Electric-field stabilization in a high-density surface superlattice
Creators: name: Feil, Thomas
name: Tranitz, Hans-Peter
name: Reinwald, Matthias
name: Wegscheider, Werner
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: semiconductor superlattices, carrier density
subject: 530 Physik
subject: 73.63.-b

description: By application of the cleaved-edge overgrowth technique, we realize a two-channel superlattice (SL) device. The structure combines the parallel transport through a low-density SL under almost homogeneous electric field conditions with that through a surface SL (SSL) with large carrier density, which is, without parallel transport, subject to pronounced field instabilities. Direct control of the SSL density allows a separation of both transport contributions. With parallel transport through the low-density SL, the current carried by the SSL is characteristic for a SL with homogeneous field distribution. In particular, it exhibits negative differential conductivity over a wide range of applied electric fields. In contrast, for current only through the SSL clear electric-field instabilities, typical for SLs at high densities are observed. Thus, by means of the parallel transport channel, field instabilities are avoided and transport in high-density SLs with a homogeneous field distribution becomes accessible.
Atom-mirror cooling and entanglement using cavity Electromagnetically Induced Transparency
Creators: name: Genes, Claudiu
name: Ritsch, Helmut
name: Drewsen, Michael
name: Dantan, Aurélien
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate a hybrid optomechanical system comprised of a mechanical oscillator and an atomic 3-level ensemble within an optical cavity. We show that a suitably tailored cavity field response via Electromagnetically Induced Transparency (EIT) in the atomic medium allows for strong coupling of the mechanical mirror oscillations to the collective atomic ground-state spin. This facilitates ground-state cooling of the mirror motion, quantum state mapping and robust atom-mirror entanglement even for cavity widths larger than the mechanical oscillator frequency.
Center-limb dependence of photospheric velocities in regions of emerging magnetic fields on the Sun
Creators: name: Khlystova, A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We investigate the ratio of the vertical and horizontal velocities of the photospheric plasma flows in the region of emerging magnetic fields on the Sun. We carried out a study of photospheric velocities during the first hours of the appearance of 83 active regions with magnetic flux more than 10^21 Mx with data acquired by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). The emerging magnetic fluxes under investigation were isolated from extended concentrations of existing magnetic fields; they have different spatial scales and are located at different distances from the solar disk center. We found that the values of maximum negative Doppler velocities that accompany the emergence of active region magnetic fields during the first 12 hours increase nonlinearly with the heliocentric angle. This result shows that the horizontal photospheric velocities of plasma outflows are higher than the vertical ones of the plasma upflows during the first hours of the emergence of active regions. The horizontal velocity component at the site of emerging active regions exceeds that of convective flows in the quiet Sun. A comparison between the velocities and the maximum value of the total magnetic flux has not revealed any relation.
description: 5 pages, 4 figures, accepted in A&A
Transverse-momentum parton densities: gauge links, divergences and soft factor
Creators: name: Cherednikov, I. O.
name: Stefanis, N. G.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We discuss the state-of-the-art of the theory of transverse-momentum dependent parton densities (TMD)s, paying special attention to their renormalization properties, the structure of the gauge links in the operator definition, and the role of the soft factor in the factorization formula within the TMD approach to the semi-inclusive processes. We argue that the use of the lightcone axial gauge offers certain advantages for a consistent definition of TMDs as compared to the off-the-light-cone gauges, or covariant gauges with off-the-lightcone gauge links.
description: 7 pages, no figures; needs ws-procs9x6.cls (supplied). Talk presented by the first author at Workshop on "Exclusive Reactions at High Momentum Transfer", 18-21 May 2010, Thomas Jefferson National Accelerator Facility (Newport News, VA, USA)
Tuning independently Fermi energy and spin splitting in Rashba systems: Ternary surface alloys on Ag(111)
Creators: name: Mirhosseini, H.
name: Ernst, A.
name: Ostanin, S.
name: Henk, J.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: By detailed first-principles calculations we show that the Fermi energy and the Rashba splitting in disordered ternary surface alloys (BiPbSb)/Ag(111) can be independently tuned by choosing the concentrations of Bi and Pb. The findings are explained by three fundamental mechanisms, namely the relaxation of the adatoms, the strength of the atomic spin-orbit coupling, and band filling. By mapping the Rashba characteristics,i.e.the splitting and the Rashba energy, and the Fermi energy of the surface states in the complete range of concentrations. Our results suggest to investigate experimentally effects which rely on the Rashba spin-orbit coupling in dependence on spin-orbit splitting and band filling.
description: 11 pages, 3 figures
Dynamic-mechanical thermoanalysis test: a rapid alternative for accelerated freeze-thaw stability evaluation of W/O emulsions
Creators: name: Cekic, Nebojsa D.
name: Savic, Sanela M.
name: Savic, Snezana D.
Publisher: name: Taylor & Francis
Year: 2019
Subjects: subject: Biophysics
subject: Medicine
subject: Neuroscience
subject: Physiology
subject: FOS: Biological sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Sociology
subject: FOS: Sociology

description: Objective: The aim of this study was to develop a new dynamic-mechanical thermoanalysis (DMTA) test and evaluate its performance as rapid rheological alternative to routinely used freeze-thaw test for accelerated stability testing of water-in-oil (W/O) emulsions. Significance: Due to inherent emulsion instability and versatilities of storage and use conditions, stability assessment of emulsion products still remains complex and challenging task. Recommended stability evaluation protocols are time-consuming, imposing need for alternate test procedures, especially in the early stage of product development, as well as in the quality assurance setting, including quality control. Methods: Five model W/O emulsions were prepared, comprehensively rheologically characterized (continual and oscillatory tests), and subjected to stability evaluation through freeze-thaw test in stability chamber and DMTA tests using an air-bearing rheometer. Results: Analyzed emulsions displayed desired shear-thinning flow behavior with yield point. The storage modulus dominated over the loss modulus in the linear viscoelastic regions of amplitude sweeps, as was the case in frequency sweeps over entire frequency range. Statistical comparison showed good agreement between freeze-thaw test, as a method available and used in daily routine work for accelerated evaluation of the physical stability, and DMTA test, as a rheological simulation of the said routine method. Duration of DMTA test was significantly shorter compared to routine but lengthy freeze-thaw test (3.5 h versus 12 days). Conclusions: According to our results, DMTA test could be a rapid alternative for accelerated freeze-thaw stability evaluation of W/O emulsions, thus enabling high formulating turnover and decision making in R&D and QC departments.
Fueling lobes of radio galaxies: statistical particle acceleration and the extragalactic gamma-ray background
Creators: name: Massaro, F.
name: Ajello, M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The recent discovery of the gamma-ray emission from the lobes of the closest radio galaxy Centaurus A by Fermi implies the presence of high-energy electrons at least up to gamma ~ 10^5 - 10^6. These high-energy electrons are required to interpret the observed gamma-ray radiation in terms of inverse Compton emission off the cosmic microwave background (IC/CMB); the widely accepted scenario to describe the X-ray emission of radio galaxy lobes. In this Letter, we consider the giant radio lobes of FR II radio galaxies showing that it is possible to maintain electrons at energies gamma ~ 10^5 - 10^6, assuming an acceleration scenario (driven by turbulent magnetic fields) that compensates the radiative losses. In addition, we consider the contribution to the diffuse extragalactic gamma-ray background due to the IC/CMB emission of FR IIs' lobes showing its relevance in the keV to MeV energy range.
description: 5 pages, 3 figures, ApJ Letter accepted
IGR J16547-1916/1RXS J165443.5-191620 -- a New Intermediate Polar from the INTEGRAL Galactic Survey
Creators: name: Lutovinov, A.
name: Burenin, R.
name: Revnivtsev, M.
name: Suleimanov, V.
name: Tkachenko, A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the results of our optical identification of the X-ray source IGR J16547-1916 detected by the INTEGRAL observatory during a deep all-sky survey. Analysis of the spectroscopic data from the SWIFT and INTEGRAL observatories in the X-ray energy band and from the BTA (Special Astrophysical Observatory) telescope in the optical band has shown that the source is most likely an intermediate polar -- an accreting white dwarf with the mass of M~0.85 M_Sun in a low-mass binary system. Subsequent studies of the object's rapid variability with the RTT-150 telescope have confirmed this conclusion by revealing periodic pulsations of its optical emission with a period of ~550 s.
description: 10 pages, 4 figures, will be published in Astronomy Letters, V.36, N12, PP.904-909, 2010
Adaptive model-predictive control and its applications in paper-making processes
Creators: name: Lu, Qiugang
Publisher: name: University of British Columbia
Year: 2018

description: Model-based controllers such as model-predictive control (MPC) have become dominated control strategies for various industrial applications including sheet and film processes such as the machine-directional (MD) and cross-directional (CD) processes of paper machines. However, many industrial processes may have varying dynamics over time and consequently model-based controllers may experience significant performance loss under such circumstances, due to the presence of model-plant mismatch (MPM). We propose an adaptive control scheme for sheet and film processes, consisting of performance assessment, MPM detection, optimal input design, closed-loop identification and controller adaptive tuning. In this work, four problems are addressed for the above adaptive control strategy. First, we extend conventional performance assessment techniques based on minimum-variance control (MVC) to the CD process, accounting for both spatial and temporal performance limitations. A computationally efficient algorithm is provided for large-scale CD processes. Second, we propose a novel closed-loop identification algorithm for the MD process and then extend it to the CD process. This identification algorithm can give consistent parameter estimates asymptotically even when true noise model structure is not known. Third, we propose a novel MPM detection method for MD processes and then further extend it to the CD process. This approach is based on routine closed-loop identifications with moving windows and process model classifications. A one-class support vector machine (SVM) is used to characterize normal process models from training data and detect the MPM by predicting the classification of models from test data. Fourth, an optimal closed-loop input design is proposed for the CD process based on noncausal modeling to address the complexity from high-dimensional inputs and outputs. Causal-equivalent models can be obtained for the CD noncausal models and thus closed-loop optimal input design can be performed based on the causal-equivalent models. The effectiveness of the proposed algorithms are verified by industrial examples from paper machines. It is shown that the developed adaptive controllers can automatically tune controller parameters to account for process dynamic changes, without the interventions from users or recommissioning the process. Therefore, the proposed methodology can greatly reduce the costs on the controller maintenance in the process industry.
Scaling and anisotropy of magnetohydrodynamic turbulence in a strong mean magnetic field
Creators: name: Grappin, Roland
name: Müller, Wolf-Christian
Publisher: name: arXiv
Year: 2010
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: We present a new analysis of the anisotropic spectral energy distribution in incompressible magnetohydrodynamic (MHD) turbulence permeated by a strong mean magnetic field. The turbulent flow is generated by high-resolution pseudo-spectral direct numerical simulations with large-scale isotropic forcing. Examining the radial energy distribution for various angles $θ$ with respect to $\mathbf{B}_0$ reveals a specific structure which remains hidden when not taking axial symmetry with respect to $B_0$ into account. For each direction, starting at the forced large-scales, the spectrum first exhibits an amplitude drop around a wavenumber $k_0$ which marks the start of a scaling range and goes on up to a dissipative wavenumber $k_d(θ)$. The 3D spectrum for $k \ge k_0$ is described by a single $θ$-independent functional form $F(k/k_d)$, the scaling law being the same in every direction. The previous properties still hold when increasing the mean field from $B_0=5$ up to $B_0=10 \ b_{rms}$, as well as when passing from resistive to ideal flows. We conjecture that at fixed $B_0$ the direction-independent scaling regime is reached when increasing the Reynolds number above a threshold which raises with increasing $B_0$. Below that threshold critically balanced turbulence is expected.
description: Submitted to PRE
The effect of implementing a Modified Early Warning Score on patient outcomes in an inpatient cardiology ward
Creators: name: Grespan, Patricia
Publisher: name: University of British Columbia
Year: 2018

description: Background: The Modified Early Warning System (MEWS) was implemented on an in-patient cardiology unit with the aim of improving patient safety, increasing efficiency of transfer of unstable patients to critical care, more timely physician interventions, decreasing code blue calls, and improved communication between nurses and physicians. Objective: To investigate the association between the implementation of a Modified Early Warning System (MEWS) on a cardiology unit with patient outcomes: proportion of code blue calls and in-hospital mortality and mean lengths of hospital stay. Method: This study used a quasi-experimental design. Data sources included: discharge separation files and archived cardiac arrest data. Interrupted time series analysis was used to compare trends before and after MEWS implementation. Results: Results from the generalized least-squares model reveal that there was an increase of 1.04 in the code blue rate following the implementation of the MEWS; however, this was not statistically significant (95% CI -0.0158-2.0991, p = 0.0671). There was a sustained significant increase in the trend of 0.33 of code blues called per month (95% CI 0.1932-0.4658, p = 0.0001). There was a decrease of 0.05 (95% CI -1.2328-1.3328, p = 0.94) of in-hospital mortality and a decrease of the in-hospital mortality trend of 0.16 per month (95% CI -0.0207-0.3374, p = 0.098) following the implementation of the MEWS, however, neither were statistically significant. A decrease of 0.07 in the mean length of stay (95% CI -1.6784-1.5322, p = 0.93) and a decrease in the trend of about 0.18 per month in the mean length of stay (95% CI -0.0429-0.4052, p = 0.13) following the implementation of the MEWS was found, but neither was statistically significant. Conclusion: This study provides evidence that the use of a MEWS may not be associated with patient outcomes. Recommendations for future research and implications to nursing practice are addressed. Interrupted time series analysis was a strong study design for examining the use of the MEWS and patient outcomes; It is a method that should be utilized in nursing research.
Synthesis of high payload nanohydrogels for the ecapsulation of hydrophilic molecules via inverse miniemulsion polymerization: caffeine as a case study
Creators: name: Artusio, Fiora
name: Ferri, Ada
name: Gigante, Valeria
name: Massella, Daniele
name: Mazzarino, Italo
name: Sangermano, Marco
name: Barresi, Antonello
name: Pisano, Roberto
Publisher: name: Taylor & Francis
Year: 2019
Subjects: subject: Biophysics
subject: Biochemistry
subject: Space Science
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences

description: The association of an active principle with a nanocarrier is known to improve its stability and protect it from external factors. Nevertheless, loading of nanoparticles with highly hydrophilic substances like caffeine remains a tricky issue. In the present study, inverse miniemulsion systems were successfully coupled to UV radiation to synthesize polymeric nanohydrogels for drug delivery. The proper choice of the continuous and dispersed phase chemical composition led to the entrapment of active principle into the miniemulsion droplets. Our confinement-based strategy enabled unprecedented caffeine encapsulation efficiency inside 100-nm particles. Dimensional, thermal, and spectroscopic characterizations were carried out to investigate both unloaded and loaded nanohydrogels. Furthermore, in vitro release studies evaluated caffeine release kinetics from nanohydrogels by means of dialysis tests. It was demonstrated that controlled and sustained release occurred within the first 50 hours. Experimental data were found to fit the Higuchi model suggesting that the active principle release is diffusion controlled.
r-modes in low temperature colour-flavour-locked superconducting quark star
Creators: name: Andersson, N.
name: Haskell, B.
name: Comer, G. L.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present the first multi-fluid analysis of a dense neutron star core with a deconfined colour-flavour-locked superconducting quark component. Accounting only for the condensate and (finite temperature) phonons, we make progress by taking over results for superfluid $^4$He. The resultant two-fluid model accounts for a number of additional viscosity coefficients (compared to the Navier-Stokes equations) and we show how they enter the dissipation analysis for an oscillating star. We provide simple estimates for the gravitational-wave driven r-mode instability, demonstrating that the various phonon processes that we consider are not effective damping agents. Even though the results are likely of little direct astrophysical importance (since we consider an overly simplistic stellar model) our analysis represents significant technical progress, laying the foundation for more detailed numerical studies and preparing the ground for the inclusion of additional aspects (in particular associated with kaons) of the problem.
description: revtex, 1 eps figure
Experimental investigation of the edge states structure at fractional filling factors
Creators: name: Deviatov, E. V.
name: Dolgopolov, V. T.
name: Lorke, Axel
name: Wegscheider, Werner
name: Wieck, A. D.
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik
subject: 71.30.+h - 73.40.Qv

description: We experimentally study the electron transport between edge states in the fractional quantum Hall effect regime. We find an anomalous increase of the transport across the 2/3 incompressible fractional stripe in comparison with the theoretical predictions for the smooth edge potential profile. We interpret our results as a first experimental demonstration of the intrinsic structure of the incompressible stripes arising at the sample edge in the fractional quantum Hall effect regime.
Near-infrared polarimetry as a tool for testing properties of accreting super-massive black holes
Creators: name: Zamaninasab, M.
name: Eckart, A.
name: Dovciak, M.
name: Karas, V.
name: Schoedel, R.
name: Witzel, G.
name: Sabha, N.
name: Garcia-Marin, M.
name: Kunneriath, D.
name: Muzic, K.
name: Straubmeier, C.
name: Valencia-S, M.
name: Zensus, J. A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Several massive black holes exhibit flux variability on time scales that correspond to source sizes of the order of few Schwarzschild radii. We survey the potential of near-infrared and X-ray polarimetry to constrain physical properties of such black hole systems, namely their spin and inclination. We have focused on a model where an orbiting hot spot is embedded in an accretion disk. A new method of searching for the time-lag between orthogonal polarization channels is developed and applied to an ensemble of hot spot models that samples a wide range of parameter space. We found that the hot spot model predicts signatures in polarized light which are in the range to be measured directly in the near future. However, our estimations are predicted upon the assumption of a Keplerian velocity distribution inside the flow where the dominant part of the magnetic field is toroidal. We also found that if the right model of the accretion flow can be chosen for each source (e.g. on the basis of magnetohydrodynamics simulations) then the black hole spin and inclination can be constrained to a small two-dimensional area in the spin-inclination space. The results of the application of the method to the available near-infrared polarimetric data of Sagittarius A* (Sgr A*) is presented. It is shown that even with the currently available data the spin and inclination of Sgr A* can be constrained. Next generations of near-infrared and X-ray polarimeters should be able to exploit this tool.
description: 12 pages, 13 figures, accepted for publication in MNRAS
Haptic cues in bimanual cooperative transport of large objects
Creators: name: Shim, Jaehyun
Publisher: name: University of British Columbia
Year: 2018

description: As the interest in, and demand for, personal and service robots increase, research studies in human-robot interaction, especially involving physical contact between robots and humans, have become increasingly important. As an example of physical human-robot interaction (pHRI) research, cooperative object transport has been substantially investigated by many researchers. However, there is a gap in studies on bimanual cooperative object transport, a carrying mode essential for transport of large objects. This research investigated human-human haptic interaction during cooperative bimanual transport of a large object. Eight pairs of human subjects, leader and follower dyads, were instructed to carry a large object with both hands and move cooperatively in the anteroposterior direction. The study focused on two haptic cues, the average rate of change of force (ARCF), and the interaction duration ($t_{interaction}$) employed by leaders and followers during the initiation phase of object transports. A custom-designed frame mounted with a load cell and an accelerometer was built to measure haptic interaction and transport movement in the anteroposterior direction. The experimental data showed that the leaders employed a repetitive ARCF during the initiation phase across trials. The other haptic cue $t_{interaction}$ for followers to respond to the leader’s initiation was also found to be repetitive. Modeling of the above-mentioned findings was conducted. The impedance model of a human arm during the initiation phase of bimanual cooperative transport was computed from the experimental data. Next, the expected interaction duration ($\hat{t}_{interaction}$) computed by inputting the average rate of change of force to the impedance model was compared to the average value of the actual interaction duration ($\bar{t}_{interaction}$) collected through the human-human study. The comparison showed that $\hat{t}_{interaction}$ was larger than $\bar{t}_{interaction}$ but in a comparable range. The findings of the human-human bimanual cooperative object transport study and subsequent modeling provide a basis for future development of a controller for human-robot cooperative transport of a large object.
Local strain and potential distribution induced by single dislocations in GaN
Creators: name: Gmeinwieser, Nikolaus
name: Gottfriedsen, P.
name: Schwarz, Ulrich
name: Wegscheider, Werner
name: Clos, R.
name: Krtschil, A.
name: Krost, A.
name: Weimar, Andreas
name: Brüderl, G.
name: Lell, Alfred
name: Härle, Volker
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: gallium compounds, III-V semiconductors, edge dislocations, photoluminescence, elastic deformation, microscopy
subject: 530 Physik
subject: 61.72.Ff; 78.55.Cr; 78.68.+m; 81.40.Jj; 81.40.Lm; 62.20.Dc; 62.20.Fe

description: The presence of a threading edge dislocation terminated at the surface of GaN bulk substrates causes a dipole-like strain state ranging over a several micrometer square area. The local strain state is derived from microphotoluminescence mappings of the near-band-edge spectrum and is quantitatively reproduced by a three-dimensional elastic deformation model approach. These results are compared with the local electrical potential distortion due to the core charge and attracted defects as analyzed by scanning surface-potential microscopy. In contrast to the local strain, the potential profile does not show a dipole-like behavior and decreases laterally faster.
On Signatures of Twisted Magnetic Flux Tube Emergence
Creators: name: Dominguez, Santiago Vargas
name: MacTaggart, David
name: Green, Lucie
name: van Driel-Gesztelyi, Lidia
name: Hood, Alan
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recent studies of NOAA active region 10953, by Okamoto {\it et al.} ({\it Astrophys. J. Lett.} {\bf 673}, 215, 2008; {\it Astrophys. J.} {\bf 697}, 913, 2009), have interpreted photospheric observations of changing widths of the polarities and reversal of the horizontal magnetic field component as signatures of the emergence of a twisted flux tube within the active region and along its internal polarity inversion line (PIL). A filament is observed along the PIL and the active region is assumed to have an arcade structure. To investigate this scenario, MacTaggart and Hood ({\it Astrophys. J. Lett.} {\bf 716}, 219, 2010) constructed a dynamic flux emergence model of a twisted cylinder emerging into an overlying arcade. The photospheric signatures observed by Okamoto {\it et al.} (2008, 2009) are present in the model although their underlying physical mechanisms differ. The model also produces two additional signatures that can be verified by the observations. The first is an increase in the unsigned magnetic flux in the photosphere at either side of the PIL. The second is the behaviour of characteristic photospheric flow profiles associated with twisted flux tube emergence. We look for these two signatures in AR 10953 and find negative results for the emergence of a twisted flux tube along the PIL. Instead, we interpret the photospheric behaviour along the PIL to be indicative of photospheric magnetic cancellation driven by flows from the dominant sunspot. Although we argue against flux emergence within this particular region, the work demonstrates the important relationship between theory and observations for the successful discovery and interpretation of signatures of flux emergence.
description: 14 pages, 8 figures, accepted for publication in Solar Physics
Noninvasive detection of charge rearrangement in a quantum dot in high magnetic fields
Creators: name: Fricke, C.
name: Rogge, M. C.
name: Harke, B.
name: Reinwald, Matthias
name: Wegscheider, Werner
name: Hohls, F.
name: Haug, R. J.
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik
subject: 73.63.Kv, 72.20.My, 73.23.Hk

description: We demonstrate electron redistribution caused by magnetic field on a single quantum dot measured by means of a quantum point contact as noninvasive detector. Our device, which is fabricated by local anodic oxidation, allows us to control independently the quantum point contact and all tunneling barriers of the quantum dot. Thus we are able to measure both the change of the quantum dot charge and also changes of the electron configuration at constant number of electrons on the quantum dot. We use these features to exploit the quantum dot in a high magnetic field where transport through the quantum dot displays the effects of Landau shells and spin blockade. We confirm the internal rearrangement of electrons as function of the magnetic field for a fixed number of electrons on the quantum dot.
Density wave patterns for fermionic dipolar molecules on a square optical lattice: Mean-field-theory analysis
Creators: name: Mikelsons, K.
name: Freericks, J. K.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We model a system of ultracold fermionic dipolar molecules on a two-dimensional square lattice. Assuming that the molecules are in their nondegenerate hyperfine ground state, and that the dipole moment is polarized perpendicular to the plane (as in the recent experiments on 40K-87Rb molecules), we approximate these molecules as spinless fermions with long range repulsive dipolar interactions. We use mean field theory to obtain the restricted phase diagram as a function of the filling, the strength of interaction and the temperature. We find a number of ordered density wave phases in the system, as well as phase separation between these phases. A Monte Carlo analysis shows that the higher-period phases are usually suppressed in the exact solution.
description: 8 pages, 7 figures
From the Equations of Motion to the Canonical Commutation Relations
Creators: name: Ercolessi, Elisa
name: Marmo, Giuseppe
name: Morandi, Giuseppe
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The problem of whether or not the equations of motion of a quantum system determine the commutation relations was posed by E.P.Wigner in 1950. A similar problem (known as "The Inverse Problem in the Calculus of Variations") was posed in a classical setting as back as in 1887 by H.Helmoltz and has received great attention also in recent times. The aim of this paper is to discuss how these two apparently unrelated problems can actually be discussed in a somewhat unified framework. After reviewing briefly the Inverse Problem and the existence of alternative structures for classical systems, we discuss the geometric structures that are intrinsically present in Quantum Mechanics, starting from finite-level systems and then moving to a more general setting by using the Weyl-Wigner approach, showing how this approach can accomodate in an almost natural way the existence of alternative structures in Quantum Mechanics as well.
description: 199 pages; to be published in "La Rivista del Nuovo Cimento" (www.sif.it/SIF/en/portal/journals)
Control and Detection of Singlet-Triplet Mixing in a Random Nuclear Field
Creators: name: Koppens, F. H. L.
name: Folk, J. A.
name: Elzermann, J. M.
name: Hanson, R.
name: Beveren, L. H. Willems van
name: Vink, I. T.
name: Tranitz, Hans-Peter
name: Wegscheider, Werner
name: Kouwenhoven, Leo P.
name: Vandersypen, L. M. K.
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: 530 Physik

description: We observed mixing between two-electron singlet and triplet states in a double quantum dot, caused by interactions with nuclear spins in the host semiconductor. This mixing was suppressed when we applied a small magnetic field or increased the interdot tunnel coupling and thereby the singlet-triplet splitting. Electron transport involving transitions between triplets and singlets in turn polarized the nuclei, resulting in marked bistabilities. We extract from the fluctuating nuclear field a limitation on the time-averaged spin coherence time T of 25 nanoseconds. Control of the electron-nuclear interaction will therefore be crucial for the coherent manipulation of individual electron spins.
Local fuse to improve the behavior of concentric braces
Creators: name: Kachooee, Ali
name: Kafi, Mohammad Ali
name: Gerami, Mohsen
Publisher: name: Санкт-Петербургский политехнический университет Петра Великого
Year: 2018
Subjects: subject: local fuse
subject: concentric brace
subject: ductility
subject: energy dissipation capacity
subject: load bearing capacity
subject: steel structure.
subject: местный предохранитель
subject: концентрический раскос
subject: податливость
subject: способность к рассеиванию энергии
subject: грузоподъемность
subject: стальная конструкция

description: The concentrically braced system is one of the most common lateral load bearing systems among steel structures. These systems have remarkable lateral stiffness and strength, but their compressive buckling prevents them from being ductile and absorbing optimal energy. In this study to solve this problem, by using numerical and experimental studies, a heuristic method is presented. In this method, a local fuse is used along the rectangular hollow section brace. This fuse is mounted by internal and external auxiliary elements to prevent its local buckling under compressive load. This makes the brace behave in a similar manner in both tensile and compressive cyclic loads, resulting in ductile behavior and high-energy absorption. Also in this study, by using numerical results, an investigation is done for the proper position of the fuse along the braces and its optimal shape.
Growth of (Ga,Mn)As on GaAs(0 0 1) and (3 1 1)A in a high-mobility MBE system
Creators: name: Reinwald, Matthias
name: Wurstbauer, Ursula
name: Döppe, Matthias
name: Kipferl, Wolfgang
name: Wagenhuber, K.
name: Tranitz, Hans-Peter
name: Weiss, Dieter
name: Wegscheider, Werner
Publisher: name: Universität Regensburg
Year: 2005
Subjects: subject: A3. Molecular beam epitaxy; B1. GaMnAs; B2. Magnetic materials; B2. Semiconducting materials
subject: 530 Physik
subject: 75.50.Pp; 61.82.Fk; 71.20.Nr

description: We demonstrate the possibility to produce both GaAs/AlGaAs heterostructures with high electron mobilities and (Ga,Mn)As by molecular beam epitaxy (MBE) in the same growth chamber. The (Ga,Mn)As samples have been grown on (0 0 1) and (3 1 1)A GaAs substrates and show state of the art quality. Immediately after (Ga,Mn)As growth, two-dimensional electron systems have been produced which show electron mobilities of up to View the MathML source. Photoluminescence measurements reveal that no manganese has been incorporated into these samples. Magnetotransport measurements on (Ga,Mn)As samples show an anomalous Hall effect if the magnetic field is oriented perpendicular to the sample surface and a giant planar Hall effect if the field is parallel to the surface. By rotating the sample in the field, the magnetic anisotropy of the samples can be analyzed. The high quality GaAs/AlGaAs heterostructures that can be produced in the same MBE system provide an excellent basis for future experiments combining high-mobility heterostructures with ferromagnetic semiconductors.
Treatment of wastewater resulting from iron ore beneficiation
Creators: name: Budykina, Tatyana
Publisher: name: Санкт-Петербургский политехнический университет Петра Великого
Year: 2018
Subjects: subject: wastewater
subject: iron ore
subject: beneficiation
subject: magnetic separation
subject: suspended solids
subject: hydraulic size
subject: sedimentation
subject: coagulants
subject: flocculants
subject: сточные воды
subject: железная руда
subject: обогащение
subject: магнитная сепарация
subject: взвешенные вещества
subject: гидравлическая крупность
subject: отстаивание
subject: коагулянты
subject: флокулянты

description: The overall objective of this article is to study the potential of the reagent treatment of wastewater resulting from the iron ore beneficiation process, as well as preventing the discharge of the wastewater into the open waters. The wastewater at the Mikhailovskii iron ore beneficiation plant (Kursk Region, Russia) discharged into a tailings pond has become an object of the research. This article looks at the sedimentation kinetics of the wastewater resulting from the wet magnetic separation of iron ores. The results of the kinetic studies allow one to predict the efficiency of water clarification and the necessary duration of sedimentation of the recycled water of the iron ore processing plant in sedimentation facilities. It has been experimentally shown that the wastewater resulting from iron ore beneficiation plants contains kinetically stable suspended substances with a hydraulic size of less than 0.013 mm/s. The efficiency and time of wastewater clarification through the reagentless sedimentation depends on the hydraulic size of the suspended solids and the depth of the settling zone. The analysis proves the efficiency of an advanced wastewater treatment, which entails reagent sedimentation with the use of aluminum polyoxychloride Aqua-Aurat 18 and flocculant Praestol 853. This approach helps to obtain the required quality of water for discharge into open reservoirs and to reduce the concentration of suspended solids by 99.6 % and total dissolved solids by 30 %. The preferable reagents dose, their ratio, as well as the method of the advanced wastewater treatment are determined.
Finite element models in stresses for bending plates
Creators: name: Tyukalov, Yury
Publisher: name: Санкт-Петербургский политехнический университет Петра Великого
Year: 2018
Subjects: subject: finite element method
subject: moments approximation
subject: bending plates
subject: buildings
subject: constructions
subject: метод конечных элементов
subject: аппроксимация моментов
subject: изгибаемые пластины
subject: здания
subject: конструкции

description: Finite element models for plate bending problems are constructed on the basis of approximations of moments fields. The bending and twisting moments are approximated in the finite element area by piecewise constant functions. The solution is based on the functional of the additional energy. Algebraic equations of equilibrium of nodes of grid of finite elements are formed using the principle of possible displacements and are included in the functional with the help of Lagrange multipliers. The necessary expressions for rectangular and triangular finite elements are obtained. Calculations of square clamped and hinged-supported plates on the action of uniformly distributed load are performed. Comparison of the obtained results with the results by the finite element method calculations in displacements is presented. It is shown that the presented method of calculating bent plates by the finite element method in stresses has the property of convergence from above. The displacements obtained by this method converge to the exact values from above, while the values of the moments is determined with reserve. When the grid of finite elements is crushed, the difference of the two solutions, in stresses and in displacements, decreases monotonically and the accuracy of the obtained results can be estimated from the value of this difference.
Massive young disks around Herbig Ae stars
Creators: name: Boissier, Jeremie
name: Alonso-Albi, Tomas
name: Fuente, Asuncion
name: Berne, Olivier
name: Bachiller, Rafael
name: Neri, Roberto
name: Ginard, David
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Herbig Ae stars (HAe) are the precursors of Vega-type systems and, therefore, crucial objects in planet formation studies. Thus far, only a few disks associated with HAe stars have been studied using millimetre interferometers. Our aim is to determine the dust evolution and the lifetime of the disks associated with Herbig Ae stars. We imaged the continuum emission at 3 mm and 1.3 mm of the Herbig Ae/Be stars BD+61154, RR Tau, VY Mon and LkHa 198 using the Plateau de Bure Interferometer (PdBI). These stars are in the upper end of the stellar mass range of the Herbig Ae stars (stellar mass greater than 3 solar masses). Our measurements were used to complete the Spectral Energy Distribution (SED). The modelling of the SED, in particular the FIR-mm part, allow us to determine the masses and dust properties of these disks. We detected the disks associated with BD+61154, RR Tau and VY Mon with disk masses of 0.35 Msun, 0.05 Msun and 0.40 Msun respectively. The disk around LkHa 198 was not detected with an upper limit to the disk mass of 0.004 Msun. We detected, however, the disks associated with the younger stellar objects LkHa 198--IR and LkHa 198-mm that are located in the vicinity of LkHa 198. The fitting of the mm part of the SED reveal that the grains in the mid-plane of the disks around BD+61154, RR Tau and VY Mon have sizes of 1--1000 microns. Therefore, grains have not grown to centimetre sizes in these disks yet. These massive (M>3 Msun) and young (about 1 Myr) HAe stars are surrounded by massive (>0.04 Msun) disks with grains of micron-millimetre sizes. Although grain growth is proceeding in these disks, their evolutionary stage is prior to the formation of planetesimals. These disks are less evolved than those detected around T Tauri and Herbig Be stars.
Efficiency of activation of mineral binders in vortex-layer devices
Creators: name: Ibragimov, Ruslan
name: Korolev, Evgeny
name: Kayumov, Rashit
name: Deberdeev, Timur
name: Leksin, Vladimir
name: Sprince, Andina
Publisher: name: Санкт-Петербургский политехнический университет Петра Великого
Year: 2018
Subjects: subject: device
subject: vortex layer
subject: activation
subject: impact
subject: energy
subject: аппарат
subject: вихревой слой
subject: активация
subject: удар
subject: энергия

description: Improving the efficiency of construction composites is a relevant problem for modern-day material science. One of the ways to solve the problem consists in activating the binders by means of vortex-layer devices. Mathematical transformations produced a formula for calculating the dependency of the number of ferromagnetic-particle collision on the number and velocity of such particles, as well as on the device chamber fill factor. The results obtained by applying the proposed formula differ from D.D. Logvinenko's model by 10 % at max. We calculated the impact force, the impulse of the grinding body in the vortex-layer device, as well as the amount of applied energy per unit of mass of the ground material. It was found out that the impact force and the impulse of force were maximized in the test device. At the same time, energy applied over the grinding time necessary to even out the binder dispersion in the vortex-layer device was 2 to 4.8 times greater compared to conventional devices.
Providing Data Group Anonymity Using Concentration Differences
Creators: name: Chertov, Oleg
name: Tavrov, Dan
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: Public access to digital data can turn out to be a cause of undesirable information disclosure. That's why it is vital to somehow protect the data before publishing. There exist two main subclasses of such a task, namely, providing individual and group anonymity. In the paper, we introduce a novel method of protecting group data patterns. Also, we provide a comprehensive illustrative example.
description: 10 pages, 2 figures, 2 tables. Published in "Mathematical Machines and Systems" (http://www.immsp.kiev.ua/publications/eng/2010_3/)