cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Highly Enantioselective Michael Additions of Indole to Benzylidene Malonate Using Simple Bis(oxazoline) Ligands: Importance of Metal/Ligand Ratio
Creators: name: Rasappan, Ramesh
name: Hager, Markus
name: Gissibl, Anja
name: Reiser, Oliver
Publisher: name: Universität Regensburg
Year: 2006
Subjects: subject: 540 Chemie

description: Simple bis(oxazoline) ligands, especially azabis(oxazolines), can catalyze the copper-catalyzed addition of indoles to benzylidene malonates in up to >99% ee, provided that excess of chiral ligand is avoided. The paradigm followed in many asymmetric catalyses that an excess of chiral ligand with respect to the metal should improve enantioselectivity because a background reaction by free metal is suppressed, is not applicable here, which might call for revisiting some of the many copper(II)-bis(oxazoline)-catalyzed processes known.
An Efficient NVM based Architecture for Intermittent Computing under Energy Constraints
Creators: name: Badri, SatyaJaswanth
name: Saini, Mukesh
name: Goel, Neeraj
Publisher: name: arXiv
Year: 2022
Subjects: subject: Hardware Architecture (cs.AR)
subject: FOS: Computer and information sciences

description: Battery-less technology evolved to replace battery technology. Non-volatile memory (NVM) based processors were explored to store the program state during a power failure. The energy stored in a capacitor is used for a backup during a power failure. Since the size of a capacitor is fixed and limited, the available energy in a capacitor is also limited and fixed. Thus, the capacitor energy is insufficient to store the entire program state during frequent power failures. This paper proposes an architecture that assures safe backup of volatile contents during a power failure under energy constraints. Using a proposed dirty block table (DBT) and writeback queue (WBQ), this work limits the number of dirty blocks in the L1 cache at any given time. We further conducted a set of experiments by varying the parameter sizes to help the user make appropriate design decisions concerning their energy requirements. The proposed architecture decreases energy consumption by 17.56%, the number of writes to NVM by 18.97% at LLC, and 10.66% at a main-memory level compared to baseline architecture.
Surgical Management of Teat Laceration of a Doe
Creators: name: Mohit Yadav1 Mallikarjun K Sarasambi1 Ankit Yadav1 Akarsh Sharma1 Sonu Jaiswal2
Publisher: name: The Science world a Monthly e magazine
Year: 2023

description: At the Veterinary Clinical Complex, ANDUAT, Kumarganj, Ayodhya, U.P., an adult doe, three years of age, was brought in with a history of teat injuries sustained while grazing on barbed wire. One observed a deep longitudinal teat laceration that was infected. The teat cannel, which had fibrosed, was still producing milk. After scarification, the injured area was sutured while under sedation and regional anesthesia.In order to keep the milk flowing and avoid adhesion while the wound healed, an infant feeding tube was placed into the teat canal. Mattress sutures were used to seal the muscle and skin, respectively. After the surgery, the animal healed without any problems after three weeks.
A class of energy based ensembles in Tsallis statistics
Creators: name: Chandrashekar, R.
name: Mohammed, S. S. Naina
Publisher: name: arXiv
Year: 2011
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A comprehensive investigation is carried out on the class of energy based ensembles. The eight ensembles are divided into two main classes. In the isothermal class of ensembles the individual members are at the same temperature. A unified framework is evolved to describe the four isothermal ensembles. Such a description is provided both in the second and the third constraint formalisms. The isothermal- isobaric, grandcanonical and the generalized ensembles are illustrated through a study of the classical nonrelativistic and the extreme relativistic ideal gas models. In the adiabatic class of ensembles the individual members of the ensemble have the same value of the heat function and a unified formulation to described all the four ensembles is given. The nonrelativistic and the extreme relativistic ideal gases are studied in the isoenthalpic-isobaric ensemble, the adiabatic ensemble with number fluctuations, and, the adiabatic ensemble with number and particle fluctuations.
Quantum effects in thermal conduction: Nonequilibrium quantum discord and entanglement
Creators: name: Wu, Lian-Ao
name: Segal, Dvira
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the process of heat transfer through an entangled pair of two-level system, demonstrating the role of quantum correlations in this nonequilibrium process. While quantum correlations generally degrade with increasing the temperature bias, introducing spatial asymmetry leads to an intricate behavior: Connecting the qubits unequally to the reservoirs one finds that quantum correlations persist and increase with the temperature bias when the system is more weakly linked to the hot reservoir. In the reversed case, linking the system more strongly to the hot bath, the opposite, more natural behavior is observed, with quantum correlations being strongly suppressed upon increasing the temperature bias.
Phonon assisted tunnel ionization of deep impurities in the electric field of far-infrared radiation
Creators: name: Ganichev, Sergey
name: Prettl, Wilhelm
name: Huggard, P. G.
Publisher: name: Universität Regensburg
Year: 1993
Subjects: subject: 530 Physik
subject: 79.70.+q
subject: 71.55.Jv
subject: 72.20.Ht
subject: 72.40.+w

description: Ionization of semiconductor deep impurity centers has been observed in the far infrared, where photon energies are several factors of 10 smaller than the binding energy of the impurities. It is shown that the ionization is caused by phonon assisted tunneling in the electric field of the high power radiation. This optical method allows the investigation of the tunneling process at electric bias fields well below the threshold of avalanche breakdown.
Water Masers Associated with Star Formation in the Antennae Galaxies
Creators: name: Brogan, Crystal
name: Johnson, Kelsey
name: Darling, Jeremy
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present Very Large Array observations with 80 milliarcsecond resolution (~9 pc) of the recently discovered Galactic-analog water masers in the Antennae interacting galaxies (NGC 4038/NGC 4039; Arp244). Three regions of water maser emission are detected: two in the ``interaction region'' (IAR) and the third ~5.6'' (> 600 pc) west of the NGC 4039 nucleus. The isotropic water maser luminosities range from 1.3 to 7.7 L_sun. All three maser regions are mostly obscured in the optical/near-infrared continuum, and are coincident with massive CO-identified molecular clouds. The water maser velocities are in excellent agreement with those of the molecular gas. We also present archival VLA 3.6 cm data with ~0.28" (~30 pc) and ~0.8" (~90 pc) resolution toward the maser locations. All three maser regions are coincident with compact 3.6 cm radio continuum emission, and two are dominated by thermal ionized gas, suggesting the presence of natal super star clusters containing the equivalent of a few thousand O stars. We also present detailed comparisons between the radio data and existing HST ACS (optical) and NICMOS (near-IR) data and find that both maser regions in the IAR are also associated with Paαemission and neither source is detected shortward of 2 microns. These results highlight the potential of using Galactic-analog water masers to pinpoint sites of young super star cluster formation with exquisite angular resolution.
description: Accepted to ApJ Letters: 14 pages, 2 figures
Soliton Formation and the Core-Halo Mass Relation: An Eigenstate Perspective
Creators: name: Zagorac, J. Luna
name: Kendall, Emily
name: Padmanabhan, Nikhil
name: Easther, Richard
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: UltraLight Dark Matter (ULDM) is an axion-like dark matter candidate with an extremely small particle mass. ULDM halos consist of a spherically symmetric solitonic core and an NFW-like skirt. We simulate halo creation via soliton mergers and use these results to explore the core-halo mass relation. We calculate the eigenstates of the merged halos and use these to isolate the solitonic core and calculate its relative contribution to the halo mass. We compare this approach to using a fitting function to isolate the core and find a difference in masses up to 30%. We analyze three families of simulations: equal-mass mergers, unequal-mass mergers, and halos with a two-step merger history. Setting the halo mass to the initial mass in the simulation does not yield a consistent core-halo relationship. Excluding material "ejected" by the collision yields a core-halo relationship with a slope of 1/3 for simultaneous mergers and roughly 0.4 for two-step mergers. Our findings suggest there is no universal core-halo mass relationship for ULDM and shed light on the differing results for the core-halo relationship previously reported in the literature.
description: 10 pages, 8 figures; published in PRD, updated with referee changes
Phonons of electronic crystals in two-dimensional semiconductor moiré patterns
Creators: name: Yu, Hongyi
name: Zhou, Jiyong
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We theoretically studied the phonon properties of the triangular-, stripe- and honeycomb-type electronic crystals recently found in two-dimensional semiconductor moiré patterns. By analyzing the phonon dispersions, we found the interaction induced lattice deformation in the zigzag-stripe crystal results in a much higher dynamical stability than in the linear-stripe crystal. Moreover, chiral phonons with finite magnetizations and large Berry curvatures can emerge in triangular and honeycomb crystals under time-reversal or inversion symmetry breaking. The small effective mass of the electrons allows the selective and efficient generation of chiral phonons from the optical activity of zone-center phonons combined with the anharmonicity, facilitating the realization of the phonon Hall effect. These findings point to an exciting new platform for exploring chiral phonons and the related topological phononic devices.
Spatial and length-based models for management of migratory transboundary species : application to Pacific hake (Merluccius productus)
Creators: name: Wor Lima, Catarina
Publisher: name: University of British Columbia
Year: 2018

description: This dissertation develops new modeling tools to provide new scientific perspectives on migratory transboundary fish populations. I particularly focus on two main issues: (1) the interaction between age/size based migratory movement, spatial availability, and fisheries exploitation rates, and (2) time-varying fisheries selectivity caused by size based migration and cohort targeting. I use Pacific hake (Merluccius productus) as a case study. Pacific hake occurs off the Pacific coast of the U.S.A. and Canada and is characterized by ontogenetic migratory movement (older fish migrate further north), strong recruitment events, and time-varying selectivity due to targeting of strong cohorts. In this dissertation, I present two new modeling approaches, and explore the effects of spatial structure on management outcomes using a closed-loop evaluation. First, I use a Lagrangian approach to develop a migration model that describes the Pacific hake dynamics including seasonal migrations, fisheries dynamics, and cohort targeting. Second, I introduce a new stock assessment method that bypasses the requirement of estimating selectivity by using catch at length and growth parameters to produce estimates of exploitation rate at age. This method produces mixed results because of low precision in selectivity estimates. Third, I evaluate the impacts of harvest control rules on the outcomes experienced by Canada and the U.S.A while sharing the Pacific hake resource. I use the migration model described above in a closed-loop simulation to evaluate the long-term impact of 61 harvest control rules. The results indicate that there are differences in performance of harvest control rules between the two nations when maximizing potential long-term yield and log yields. This is a result of the reduced availability of the resource in Canadian waters as the overall harvest rate increases. Caps on allowable catch may help to avoid reduced availability issues. I believe that the results and conclusions presented in this dissertation can inform the future management and modeling of Pacific hake. In addition, the methods presented here could be used for management of other resources subject to time-varying selectivity and other transboundary stocks managed under agreements that do not consider spatial management explicitly.
Higher Regularity of the Free Boundary in a Semilinear System
Creators: name: Fotouhi, Morteza
name: Koch, Herbert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: In this paper we are concerned with higher regularity properties of the elliptic system \[ Δ\mathbf{u}= |\mathbf{u}|^{q-1}\mathbf{u}χ_{\{|\mathbf{u}|>0\}},\qquad\mathbf{u}=(u^1,\dots,u^m) \] for $0\leq q<1$. We show analyticity of the regular part of the free boundary $\partial\{|\mathbf{u}|>0\}$, analyticity of $|\mathbf{u}|^{\frac{1-q}2} $ and $ \frac{\mathbf{u}}{|\mathbf{u}|}$ up to the regular part of the free boundary. Applying a variant of the partial hodograph-Legendre transformation and the implicit function theorem, we arrive at a degenerate equation, which introduces substantial challenges to be dealt with. Along the lines of our study, we also establish a Cauchy-Kowalevski type statement to show the local existence of solution when the free boundary and the restriction of $ \frac{\mathbf{u}}{|\mathbf{u}|} $ from both sides to the free boundary are given as analytic data.
The orbital and superhump periods of the dwarf nova HS 0417+7445 in Camelopardalis
Creators: name: Shears, J. H.
name: Gaensicke, B. T.
name: Brady, S.
name: Dubovsky, P.
name: Miller, I.
name: Staels, B.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present the 2005-2010 outburst history of the SUUMa-type dwarf HS 0417+7445,along with a detailed analysis of extensive time-series photometry obtained in March 2008 during the second recorded superoutburst of the system. The mean outburst interval is 197 \pm 59 d, with a median of 193 d. The March 2008 superoutburst was preceeded by a precursor outburst, had an amplitude of 4.2 magnitudes, and the whole event lasted about 16 days. No superhumps were detected during the decline from the precursor outburst, and our data suggests instead that orbital humps were present during that phase. Early superhumps detected during the rise to the superoutburst maximum exhibited an unusually large fractional period excess of epsilon = 0.137 (Psh = 0.0856(88) d). Following the maximum, a linear decline in brightness followed, lasting at least 6 days. During this decline, a stable superhump period of Psh = 0.07824(2) d was measured. Superimposed on the superhumps were orbital humps, which allowed us to accurately measure the orbital period of HS 0417+7445, Porb = 0.07531(8) d, which was previously only poorly estimated. The fractional superhump period excess during the main phase of the outburst was epsilon = 0.037, which is typical for SU UMa dwarf novae with similar orbital period. Our observations are consistent with the predictions of the thermal-tidal instability model for the onset of superoutbursts,but a larger number of superoutbursts with extensive time-series photometry during the early phases of the outburst would be needed to reach a definite conclusion on the cause of superoutbursts.
description: 18 pages, 4 figures, accepted for publication in New Astronomy
Assessment of Gap and Charging Voltage Influence on Mechanical Behaviour of Joints Obtained by Magnetic Pulse Welding
Creators: name: Buiron, N.
name: Dos Santos, B.
name: Franz, G.
name: Habak, M.
name: Haye, D.
name: Jouaffre, D.
name: Morel, M.
name: Rachik, M.
name: Raoelison, R.
Publisher: name: TU Dortmund
Year: 2012
Subjects: subject: cold welding
subject: condition
subject: damage
subject: 620
subject: 670

description: This work investigates the study of the experimental weldability in magnetic pulse welding process of a one material assembly (aluminium AA6060T6) and a dissimilar metal couple (aluminium6060T6/copper). The weld quality is defined using a destructive process allowing measuring the weld dimension. A diagram charging voltage-air gap is used to establish the variance of weldability. With the criterion of width of the weld, this representation is able to determine the operational weldability window. The lower boundary is defined by the case of bad weld, i.e. an insufficient bonding, and the upper boundary by defective welds, i.e. a weld susceptible to crack. The weld is able to undergo a plastic deformation prior to failure. A large weld is more potentially ductile. A numerical modelling of a mechanical destructive push out test could be helpful to characterise the weld in a quantitative manner. Finally, the material dissymmetry as considered in this study notably reduces the weldability window because of intermetallic phase at the welded interface. For this case, the weld is found to have a rather brittle behaviour.
Effects of long-term methylphenidate use on growth and blood pressure: results of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)
Creators: name: McCarthy, Suzanne
name: Neubert, Antje
name: Man, Kenneth K. C.
name: Banaschewski, Tobias
name: Buitelaar, Jan
name: Carucci, Sara
name: Coghill, David
name: Danckaerts, Marina
name: Falissard, Bruno
name: Garas, Peter
name: Häge, Alexander
name: Hollis, Chris
name: Inglis, Sarah
name: Kovshoff, Hanna
name: Liddle, Elizabeth
name: Mechler, Konstantin
name: Nagy, Peter
name: Rosenthal, Eric
name: Schlack, Robert
name: Sonuga-Barke, Edmund
name: Zuddas, Alessandro
name: Wong, Ian C. K.
Publisher: name: Robert Koch-Institut
Year: 2018
Subjects: subject: ADHD
subject: Methylphenidate
subject: Safety
subject: Growth
subject: BMI
subject: Blood pressure
subject: 610 Medizin und Gesundheit

description: Background Concerns have been raised over the safety of methylphenidate (MPH), with regard to adverse effects on growth and blood pressure. Our study investigates whether, and to what extent, methylphenidate use in boys with ADHD is associated with having low body mass index (BMI), having low height, and increased systolic and diastolic blood pressure. Methods Data used for this study stem from the German KiGGS dataset. Three different groups of boys aged 6–15 years were included in the analysis: ADHD patients who used MPH for less than 12 months; ADHD patients who used MPH for 12 months or more; and ADHD patients without current MPH treatment. Each of these three groups was compared to a non-ADHD control group regarding low weight (BMI ≤ 3rd percentile), low height (≤3rd percentile) and raised systolic and diastolic blood pressure. For growth outcomes, boys were categorized according to age (
Oblique launching of optical surface waves by a subwavelength slit
Creators: name: Nikitin, A. Yu.
name: Garcia-Vidal, F. J.
name: Martin-Moreno, L.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: The electromagnetic field on the metal surface launched by a subwavelength slit is analytically studied, for the case when the fundamental mode inside the slit has a wavevector component along the slit axis (conical mount). Both near-field and far-field regions are discussed, and the role of surface plasmon-polaritons and Norton waves is revealed. It is shown that the distance from the slit at which NW are more intense than surface plasmons decrease with parallel wavevector, which could help experimental studies on Norton waves. Additionally, it is found that the s-polarization component, while present for any non-zero parallel wavevector, only weakly contributes to the NWs.
description: 8 pages, 5 figures
Planetary nebulae in the elliptical galaxy NGC 4649 (M 60): kinematics and distance redetermination
Creators: name: Teodorescu, A. M.
name: Mendez, R. H.
name: Bernardi, F.
name: Thomas, J.
name: Das, P.
name: Gerhard, O.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Using a slitless spectroscopy method with (a) the 8.2 m Subaru telescope and its FOCAS Cassegrain spectrograph, and (b) the ESO Very Large Telescope (VLT) unit 1 (Antu) and its FORS2 Cassegrain spectrograph, we have detected 326 planetary nebulae (PNs) in the giant Virgo elliptical galaxy NGC 4649 (M 60), and we have measured their radial velocities. After rejecting some PNs more likely to belong to the companion galaxy NGC 4647, we have built a catalog with kinematic information for 298 PNs in M 60. Using these radial velocities we have concluded that they support the presence of a dark matter halo around M 60. Based on an isotropic, two-component Hernquist model, we estimate the dark matter halo mass within 3$R_{\rm e}$ to be 4$\times10^{11} M_{\odot}$, which is almost one half of the total mass of about $10^{12} M_{\odot}$ within 3$R_{\rm e}$. This total mass is similar to that estimated from globular cluster, XMM-Newton and Chandra observations. The dark matter becomes dominant outside. More detailed dynamical modeling of the PN data is being published in a companion paper. We have also measured the $m$(5007) magnitudes of many of these PNs, and built a statistically complete sample of 218 PNs. The resulting PN luminosity function (PNLF) was used to estimate a distance modulus of 30.7$\pm$0.2 mag, equivalent to 14$\pm$1 Mpc. This confirms an earlier PNLF distance measurement, based on a much smaller sample. The PNLF distance modulus remains smaller than the surface brightness fluctuation (SBF) distance modulus by 0.4 mag.
description: Accepted for publication in ApJ; 14 figures
Poole-Frenkel Effect in Terahertz Electromagnetic Fields
Creators: name: Ganichev, Sergey
name: Diener, J.
name: Yassievich, Irina
name: Prettl, Wilhelm
Publisher: name: Universität Regensburg
Year: 1995
Subjects: subject: 530 Physik
subject: 71.55.-i
subject: 72.20.Ht
subject: 72.40.+w

description: The ionisation of deep impurity centres in germanium has been observed with radiation in the terahertz range where the photon energy is much less than the binding energy of the impurities. It is shown that for not too high radiation intensities the ionisation is caused by the Poole-Frenkel effect. As in the well-known case of d.c. fields, the electric field of the high-frequency radiation lowers the Coulomb potential barrier and enhances the thermal emission of carriers.
Light from Porous Silicon by Multiphoton Vibronic Excitation
Creators: name: Diener, J.
name: Ben-Chorin, M.
name: Kovalev, D.
name: Ganichev, Sergey
name: Koch, F.
Publisher: name: Universität Regensburg
Year: 1995
Subjects: subject: 530 Physik
subject: 33.80.Wz
subject: 42.65.Vh
subject: 68.35.Ja
subject: 78.66.Db

description: We study the emission of photons from porous Si after high-level vibrational excitation in the Si-O absorption band using a pulsed CO2 laser. Narrow resonances in the efficiency of light generation are discovered at 1030 and 1084 cm-1. Time-resolved experiments on the luminescence and the ir-induced changes in optical transparency show that the two excitation modes are characterized by different temporal responses. Additionally, their spectral distributions differ substantially. For excitation at 1030 cm-1 the familiar photoluminescence band of porous Si appears. We suggest microscopic processes responsible for the light emissions.
Sensitivity of synchrotron radiation to the superthermal electron population in mildly relativistic plasma
Creators: name: Mlodik, M. E.
name: Munirov, V. R.
name: Rubin, T.
name: Fisch, N. J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: Synchrotron radiation has markedly different behavior in $\sim 10~\textrm{keV}$ and in $\sim 100~\textrm{keV}$ plasma. We show that high-energy electrons which occupy the tail of velocity distribution function have disproportionate impact on power loss of $\sim 100~\textrm{keV}$ plasma. If electrons with energy more than a cutoff energy are redistributed while keeping the Maxwellian distribution function below cutoff energy intact, both emission and absorption of synchrotron radiation act to decrease the lost power. These novel radiation transport effects in non-equilibrium plasma suggest large utility in the deconfinement of high-energy electrons to reduce synchrotron radiation in applications where the radiation is deleterious.
description: 6 pages, 5 figures, published in PoP
Combined simulation of quasi-static deep drawing and electromagnetic forming by means of a coupled damage–viscoplasticity model at finite strains
Creators: name: Brosius, A.
name: Demir, O. K.
name: Kiliclar, Y.
name: Kwiatkowski, L.
name: Reese, S.
name: Tekkaya, A. E.
name: Vladimirov, N.
Publisher: name: TU Dortmund
Year: 2012
Subjects: subject: damage
subject: deep drawing
subject: modelling
subject: 620
subject: 670

description: The combination of quasi-static and electromagnetic pulse forming increases the formability of sheet metal forming processes. A cooperation between the institute of Applied Mechanics (IFAM) of the RWTH Aachen and the Institute of Forming Technology and Lightweight Construction (IUL) of the TU Dortmund is investigating these processes both experimentally and by simulation for the deep-drawing process of a cross-shaped cup. Aim of the work is to show and prove that with this forming strategy we obtain a more sharpened radius of the cup edges.The combined deformation process is simulated by means of finite elements using a material model developed in [1,2]. A recently proposed finite strain anisotropic viscoplastic model, taking combined nonlinear kinematic and isotropic hardening into account, is coupled with ductile damage in the context of continuum damage mechanics. For the simulation, the evolution equations for the internal variables of the constitutive model are numerically integrated in an explicit manner and the model is then implemented as a user material subroutine in the commercial finite element package LS-Dyna.
The magnetic structure of Gd_2Ti_2O_7
Creators: name: Brammall, M. I.
name: Briffa, A. K. R.
name: Long, M. W.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We attempt to solve the magnetic structure of the gadolinium analogue of `spin-ice', using a mixture of experimental and theoretical assumptions. The eventual predictions are essentially consistent with both the Mossbauer and neutron measurements but are unrelated to previous proposals. We find two possible distinct states, one of which is coplanar and the other is fully three-dimensional. We predict that close to the initial transition the preferred state is coplanar but that at the lowest temperature the ground-state becomes fully three-dimensional. Unfortunately the energetics are consequently complicated. There is a dominant nearest-neighbour Heisenberg interaction but then a compromise solution for lifting the final degeneracy resulting from a competition between longer-range Heisenberg interactions and direct dipolar interactions on similar energy scales.
description: 12 pages, 15 figures
Direct correlation between strengthening mechanisms and electrical noise in strained copper wires
Creators: name: Bellido, Natalia
name: Pautrat, Alain
name: Keller, Clement
name: Hug, Eric
Publisher: name: arXiv
Year: 2011
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We have measured the resistance noise of copper metallic wires during a tensile stress. The time variation of the main resistance is continuous up to the wire breakdown, but its fluctuations reveal the intermittent and heterogeneous character of plastic flow. We show in particular direct correlations between strengthening mechanisms and noise spectra characteristics.
description: accepted in Phys Rev B
Nonlinear far-infrared absorption in InSb at light impact ionization
Creators: name: Ganichev, Sergey
name: Diener, J.
name: Prettl, Wilhelm
Publisher: name: Universität Regensburg
Year: 1994
Subjects: subject: 530 Physik

description: A highly nonlinear far-infrared free-carrier absorption, rising with the radiation intensity, has been observed in InSb. It is shown that the nonlinearity arises from an increase in the number of free carriers caused by the generation of electron-hole pairs by light impact ionization in the radiation field of a powerful far-infrared laser. The observed nonlinearity permits the investigation of the process of impact ionization by a contactless optical method.
MPEC 2024-C67 : 2024 BD7
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2024
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2024 BD7

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Fracture mechanisms and structural fragility of human femoral cortical bone
Creators: name: Tang, Tengteng
Publisher: name: University of British Columbia
Year: 2018

description: Hip fracture has serious repercussions at both the societal and personal levels. For better fracture prevention, it is essential to understand the material changes of femoral cortical bone that contribute to hip fragility, and the deformation and fracture process during hip fractures. Therefore, the aim of this dissertation was to study the mechanisms of hip fracture from both structural and mechanical perspectives. Using quantitative backscattered electron (qBSE) imaging and polarized Raman microspectroscopy, periosteal hypermineralization in aged human proximal femur was found with significantly higher mineral content/mineral-to-matrix ratio than lamellar bone. Accompanying the increased mineralization was the “brittle” cracking behavior upon microindentation in the hypermineralized tissue. Small- and wide-angle X-ray scattering (SAXS/WAXS) measurement showed substantially thinner, shorter and more irregularly distributed mineral platelets in the hypermineralized region, indicating the material changes at the ultrastructural level. Combined second harmonic generation (SHG) and two photon excitation fluorescence (TPEF) techniques were used to study shear microcracking and its association with the organization of collagen fibrils in the femoral cortical bone. Unique arc-shaped shear microcracks, differing from either tensile or compressive microcracks, were identified at the peripheral zone of the osteons. These microcracks were further located within the “bright” lamellae where collagen fibrils are primarily oriented at the circumferential direction to the osteons’ long axes. Microcracking analysis on clinically retrieved femoral neck components identified shear, compressive and tensile microcracks associated with major fractures. The results pointed to the central role of the superior cortex in resisting a hip fracture, whereby higher density of microcracks and buckling failure were found in the superior cortical bone. BSE imaging at the fracture sites found the direct involvement of hypermineralization, which lacked crack deviation and had fewer microcracks than the tough lamellar bone. This dissertation answered fundamental questions regarding the role of femoral cortical bone in clinical hip fractures, and elucidated the underlying failure mechanisms due to microstructural changes and the complex stress states under external loading. The findings thus provided new insights into better identifying at-risk population of hip fracture.
Turkey in European Identity Politics: Key Drivers and Future Scenarios
Creators: name: Lindgaard, Jakob
name: Uyğur Wessel, Ayça
name: Stokholm Banke, Cecilie Felicia
Publisher: name: Zenodo
Year: 2018
Subjects: European Union; Turkey; EU-Turkey relations; Identity Politics; Key Drivers; Future Scenarios; Representation; Conflictual Cooperation; 1999-2017; 2023; Trends Survey; Conflictual Orientation

description: FEUTURE Online Paper No. 19

This paper presents a trends survey of identity-related primarily European representations of Turkey (but also vice versa) in the 1999-2017 timeframe with a view to identifying the most salient, pertinent, and durable drivers likely to obtain and drive the relations between Turkey and the EU into 2023. It identifies four key drivers underpinning European representations of Turkey, three drivers underpinning Turkish representations of Europe and one shared driver that collectively reveal the underlying dynamics of identity-related representations of each other, a both pivotal and often controversial aspect of EU-Turkey relations. In conclusion, the paper unfolds the nature of the likely scenario of a ‘conflictual orientation’ in 2023, and adds some initial recommendations for decision makers and stakeholders to address this often both sensitive and elusive aspect of EU-Turkey relations.
description: This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 692976. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.
Spectral Element Method for Vector Radiative Transfer Equation
Creators: name: Zhao, J. M.
name: Liu, L. H.
name: Hsu, P. -f.
name: Tan, J. Y.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Computational Physics (physics.comp-ph)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: A spectral element method (SEM) is developed to solve polarized radiative transfer in multidimensional participating medium. The angular discretization is based on the discrete-ordinates approach, and the spatial discretization is conducted by spectral element approach. Chebyshev polynomial is used to build basis function on each element. Four various test problems are taken as examples to verify the performance of the SEM. The effectiveness of the SEM is demonstrated. The h and the p convergence characteristics of the SEM are studied. The convergence rate of p-refinement follows the exponential decay trend and is superior to that of h-refinement. The accuracy and efficiency of the higher order approximation in the SEM is well demonstrated for the solution of the VRTE. The predicted angular distribution of brightness temperature and Stokes vector by the SEM agree very well with the benchmark solutions in references. Numerical results show that the SEM is accurate, flexible and effective to solve multidimensional polarized radiative transfer problems.
description: The paper have bee published in JQSRT
Selection rules for ultrafast laser excitation and detection of spin correlations dynamics in a cubic antiferromagnet
Creators: name: Fedianin, Anatolii E.
name: Kalashnikova, Alexandra M.
name: Mentink, Johan H.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Exchange interactions determine the correlations between microscopic spins in magnetic materials. Probing the dynamics of these spin correlations on ultrashort length and time scales is, however rather challenging, since it requires simultaneously high spatial and high temporal resolution. Recent experimental demonstrations of laser-driven two-magnon modes - zone-edge excitations in antiferromagnets governed by exchange coupling - posed questions about the microscopic nature of the observed spin dynamics, the mechanism underlying its excitation, and their macroscopic manifestation enabling detection. Here, on the basis of a simple microscopic model, we derive the selection rules for cubic systems that describe the polarization of pump and probe pulses required to excite and detect dynamics of nearest-neighbor spin correlations, and can be employed to isolate such dynamics from other magnetic excitations and magneto-optical effects. We show that laser-driven spin correlations contribute to optical anisotropy of the antiferromagnet even in the absence of spin-orbit coupling. In addition, we highlight the role of subleading anisotropy in the spin system and demonstrate that the dynamics of the antiferromagnetic order parameter occurs only in next-to-leading order, determined by the smallness of the magnetic anisotropy as compared to the isotropic exchange interactions in the system. We expect that our results will stimulate and support further studies of magnetic correlations on the shortest length and time scale.
description: 17 pages, 5 figures
Heating of two-dimensional electron gas and LO-phonons in delta-doped GaAs by far-infrared radiation
Creators: name: Kotel'nikov, I.
name: Shul'man, A.
name: Ganichev, Sergey
name: Varvanin, N.
name: Mayerhofer, B.
name: Prettl, Wilhelm
Publisher: name: Universität Regensburg
Year: 1996
Subjects: subject: A. quantum wells; A. semiconductors; D. electron-phonon interaction; D. phonons; E. light absorption and reflection
subject: 530 Physik

description: A change in the conductivity of the two-dimensional electron gas in δ-doped GaAs samples due to pulsed far-infrared laser irradiation has been detected. It is shown that the observed positive photoconductivity is caused by heating of 2D electrons. The energy loss of hot electrons is accomplished by scattering with nonequilibrium longitudinal optical (LO) phonons. An expression for the effective emission frequency of LO phonons coupled with electrons and the thermal bath of acoustic phonons is derived and the dependence of the emission frequency on the lattice temperature is experimentally obtained in the range 77–300 K.
Frequency Stabilization of Megawatt-Class 140 GHz Gyrotrons at W7-X Using an Off-the-Shelf PLL System
Creators: name: Krier, Laurent
name: Avramidis, Konstantinos A.
name: Braune, Harald
name: Gantenbein, Gerd
name: Illy, Stefan
name: Ioannidis, Zisis
name: Jelonnek, John
name: Laqua, Heinrich P.
name: Marsen, Stefan
name: Moseev, Dmitry
name: Noke, Frank
name: Pagonakis, Ioannis Gr.
name: Ruess, Tobias
name: Rzesnicki, Tomasz
name: Stange, Torsten
name: Thumm, Manfred
name: Wolf, Robert C.
Publisher: name: Institute of Electrical and Electronics Engineers (IEEE)
Year: 2021

description: An off-the-shelf Phase-Locked Loop (PLL) system is used to stabilize the free-running oscillation frequencies of the 140 GHz, 1 MW CW gyrotrons of the companies Thales, France, and CPI, USA, that both operate at the ECRH system of the Wendelstein 7-X (W7-X) stellarator at IPP Greifswald, Germany. Both tubes are equipped with diode-type Magnetron Injection Guns (MIGs). Considering each of both type of gyrotrons as a Voltage Controlled Oscillator (VCO), each individual gyrotron is controlled by the variation of the body voltage. The results of the experiments demonstrate the capability of the developed and implemented inexpensive off-the-shelf PLL system. It is possible to stabilize the oscillation frequency within a full -20 dB bandwidth of < 100 kHz. Applications such as Collective Thomson Scattering (CTS) systems to accurately diagnose the ions in fusion plasmas could benefit from this development in future.
Space-and Time-like Electromagnetic Kaon Form Factors
Creators: name: Raha, Udit
name: Kohyama, Hiroaki
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A simultaneous investigation of the space- and time-like electromagnetic form factors of the charged kaon is presented within the framework of light-cone QCD, with perturbative $k_T$-factorization including Sudakov suppression. The effects of power suppressed sub-leading twists and the genuine ``soft'' QCD corrections turn out to be dominant at low- and moderate-energies/momentum transfers $Q^2$. Our predictions agree well with the available moderate-energy experimental data, including the recent results from the CLEO measurements and certain estimates based on the phenomenological analyses of $J/ψ$ decays.
description: 32 pages, 7 figures
title: The empty space in abstract photography: a psychoanalytical perspective
Creators: name: Kalpadaki, Evanthia
Publisher: name: University of Kent
Year: 2022

description: The aim of the research that this thesis is based on is to explore the theoretical problems raised by the concept of photographic abstraction. These consist in the tension between the two aspects of the photographic sign, the indexical and iconic, and are examined in the context of the particular exploration of the empty space in abstract photography which I have pursued through my practice. The investigation draws mainly upon the psychoanalytic theory of transitional phenomena as proposed by Winnicott, as well as other art theories (Deleuze & Guattari, Ehrenzweig, Fer, Fuller, Greenberg, Joselit, Kuspit, Leider, Worringer) of abstraction. It explores the relationship of the abstract photographic image to notions of exteriority and interiority as these relate to the transition from the unconscious to conscious reality. The development of this research suggests the psychoanalytical concept of potential space as a contribution to an aesthetic model of abstraction. This concept is employed as a methodological tool in the development of the practical work and creates a framework for its interpretation. The concept of potential space is based on Winnicott's ideas around "playing with the real" in an intermediate area of experience between the internal and external reality, where creativity originates as a zone of fictive play that facilitates the subject's journey from "what is subjectively conceived of' to "what is objectively perceived. " The outcome of this investigation constitutes the production of a series of photographs describing an empty abstract space, one that is invested with a psychic dimension that produces the effect of ambiguity between its representational and abstract readings. It provides a redefinition of abstraction in a space of tension between the iconic and indexical aspects of the sign and opens up the space of abstraction in photography as one in which the relationship between inner and outer reality can be performed and can become a space of action and intervention.
Many-body collective neutrino oscillations: recent developments
Creators: name: Patwardhan, Amol V.
name: Cervia, Michael J.
name: Rrapaj, Ermal
name: Siwach, Pooja
name: Balantekin, A. B.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Nuclear Theory (nucl-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Neutrino flavor transformations in core-collapse supernovae and binary neutron star mergers represent a complex and unsolved problem that is integral to our understanding of the dynamics and nucleosynthesis in these environments. The high number densities of neutrinos present in these environments can engender various collective effects in neutrino flavor transformations, driven either by neutrino-neutrino coherent scattering, or in some cases, through collisional (incoherent) interactions. An ensemble of neutrinos undergoing coherent scattering among themselves is an interacting quantum many-body system -- as such, there is a tantalising prospect of quantum entanglement developing between the neutrinos, which can leave imprints on their flavor evolution histories. Here, we seek to summarize recent progress that has been made towards understanding this phenomenon.
description: 16 pages, 1 figure. Matches version to appear in Springer Handbook of Nuclear Physics (minus stylistic edits)
Neural Radiance Field Codebooks
Creators: name: Wallingford, Matthew
name: Kusupati, Aditya
name: Fang, Alex
name: Ramanujan, Vivek
name: Kembhavi, Aniruddha
name: Mottaghi, Roozbeh
name: Farhadi, Ali
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Compositional representations of the world are a promising step towards enabling high-level scene understanding and efficient transfer to downstream tasks. Learning such representations for complex scenes and tasks remains an open challenge. Towards this goal, we introduce Neural Radiance Field Codebooks (NRC), a scalable method for learning object-centric representations through novel view reconstruction. NRC learns to reconstruct scenes from novel views using a dictionary of object codes which are decoded through a volumetric renderer. This enables the discovery of reoccurring visual and geometric patterns across scenes which are transferable to downstream tasks. We show that NRC representations transfer well to object navigation in THOR, outperforming 2D and 3D representation learning methods by 3.1% success rate. We demonstrate that our approach is able to perform unsupervised segmentation for more complex synthetic (THOR) and real scenes (NYU Depth) better than prior methods (29% relative improvement). Finally, we show that NRC improves on the task of depth ordering by 5.5% accuracy in THOR.
description: 19 pages, 8 figures, 9 tables
Tunnelling ionization of autolocalized DX- centers in terahertz fields
Creators: name: Ganichev, Sergey
name: Diener, J.
name: Yassievich, Irina
name: Prettl, Wilhelm
name: Meyer, B.
name: Benz, K.
Publisher: name: Universität Regensburg
Year: 1995
Subjects: subject: 530 Physik
subject: 71.55.-i
subject: 72.20.Ht
subject: 72.40.+w

description: Tunneling ionization of DX- centers in AlxGa1-xSb has been observed in terahertz radiation fields. Tunneling times have been measured for autolocalized and on-site deep impurities. It is shown that in one case the tunneling time is smaller and in the other larger than the reciprocal temperature multiplied by a universal constant due to the different tunneling trajectories. This allows one to distinguish in a direct way between the two types of configuration potentials of impurities.