cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Pre-main Sequence stars \\ In an eccentric orbit \\ Clues to formation?
Creators: name: Walter, Frederick M
name: Hebb, Leslie
Publisher: name: Zenodo
Year: 2021
Subjects: pre-main-sequence stars

description: RX J1901.1-3648 (2MASS J19010971-3647528) was discovered in a ROSAT HRI observation of the Corona Australis star forming region. Initial optical spectroscopic followups showed it to be an SB2 system of two similar mid-K PMS stars. Over 4 nights the two spectra closed in velocity by 7 km/s. Twenty five years later we got around to investigating the orbit. It is a high-eccentricity system with asynchronous rotators. The Gaia parallax (6.55 mas) and proper motion confirm its membership in the CrA SFR.
Noncommutative vector bundles over fuzzy CP^N and their covariant derivatives
Creators: name: Dolan, Brian P.
name: Huet, Idrish
name: Murray, Sean
name: O'Connor, Denjoe
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We generalise the construction of fuzzy CP^N in a manner that allows us to access all noncommutative equivariant complex vector bundles over this space. We give a simplified construction of polarization tensors on S^2 that generalizes to complex projective space, identify Laplacians and natural noncommutative covariant derivative operators that map between the modules that describe noncommuative sections. In the process we find a natural generalization of the Schwinger-Jordan construction to su(n) and identify composite oscillators that obey a Heisenberg algebra on an appropriate Fock space.
description: 34 pages, v2 contains minor corrections to the published version
Optical theorem and indefinite metric in $λϕ^4$ delta-theory
Creators: name: Avila, Ricardo
name: Reyes, Carlos M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A class of effective field theory called delta-theory, which improves ultraviolet divergences in quantum field theory, is considered. We focus on a scalar model with a quartic self-interaction term and construct the delta theory by applying the so-called delta prescription. We quantize the theory using field variables that diagonalize the Lagrangian, which include a standard scalar field and a ghost or negative norm state. As well known, the indefinite metric may lead to the loss of unitary of the $S$-matrix. We study the optical theorem and check the validity of the cutting equations for three processes at one-loop order, and found suppressed violations of unitarity in the delta coupling parameter of the order of $ξ^4$.
description: 7 pages, 4 figures
Polarization puts a New Spin on Physics
Creators: name: Ellis, John
Publisher: name: arXiv
Year: 2007
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Polarization and spin effects are useful for probing the Standard Model, in both the electroweak sector and the strong sector, where the spin decomposition of the nucleon is still a hot topic, with important new data on the net polarizations of the gluon and the strange quarks. Spin phenomena are also useful in searches for new physics, for example via measurements of the anomalous magnetic moment of the muon and searches for electric dipole moments. The cross sections for the direct detection of dark matter may also have an important spin-dependent component, related to the spin decomposition of the nucleon, that could be an important diagnostic tool. Polarization effects are also important diagnostic aids for high-energy experiments at electron-proton, proton-proton and electron-positron colliders.
description: 14 pages, 7 figures, Plenary Talk at the 17th International Spin Physics Symposium, SPIN2006, held in Kyoto, Japan, from October 2 to 7, 2006
Preliminary mass loss results from a survey of stellar winds for young, Sun-like stars
Creators: name: Evensberget, Dag
name: Carter, Brad
name: Marsden, Stephen
name: Brookshaw, Leigh
Publisher: name: Zenodo
Year: 2021
Subjects: Cool Stars on the main sequence

description: We present current results from a project aiming to clarify how stellar winds evolve during the first billion years of the main sequence evolution of solar-type stars, and the implications for early solar evolution. This project is based on the extensive TOUPIES survey of stellar magnetic fields, with surface radial field maps used to model stellar winds via Space Weather Modelling Framework codes. We also explore numerical methods for producing wind models verifiable through direct comparisons with observations of the modern-day Sun. We find that a modelling approach used with solar magnetograms can be efficiently extended to survey a range of young solar-type stars with magnetic field strengths up to two orders of magnitude greater, but with some caveats regarding the assumptions needed and the interpretations gained from solar as well as stellar models. In our preliminary models wind mass loss does not exceed 1010 kg/s.
description: {"references": ["Folsom C. P., et al., 2016, MNRAS, 457, 580", "Folsom C. P., et al., 2018, MNRAS, 474, 4956"]}
The distance to the Orion Nebula Cluster
Creators: name: Jeffries, R. D.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The distance to the Orion Nebula Cluster (ONC) is estimated using the rotational properties of its low-mass pre main-sequence (PMS) stars. Rotation periods, projected equatorial velocities and distance-dependent radius estimates are used to form an observational sin i distribution (where i is the axial inclination), which is modelled to obtain the distance estimate. A distance of 440+/-34 pc is found from a sample of 74 PMS stars with spectral types between G6 and M2, but this falls to 392+/-32 pc when PMS stars with accretion discs are excluded on the basis of their near-infrared excess. Since the radii of accreting stars are more uncertain and probably systematically underestimated, then this closer distance is preferred. The quoted uncertainties include statistical errors and uncertainties due to a number of systematic effects including binarity and inclination bias. This method is geometric and independent of stellar evolution models, though does rely on the assumption of random axial orientations and the Cohen & Kuhi (1979) effective temperature scale for PMS stars. The new distance is consistent with, although lower and more precise, than most previous ONC distance estimates. A closer ONC distance implies smaller luminosities and an increased age based on the positions of PMS stars in the Hertzsprung-Russell diagram.
description: Accepted for publication in MNRAS (12 pages) Table 1 available from the author
Ultracold atom interferometry in space
Creators: name: Lachmann, Maike D.
name: Ahlers, Holger
name: Becker, Dennis
name: Dinkelaker, Aline N.
name: Grosse, Jens
name: Hellmig, Ortwin
name: Müntinga, Hauke
name: Schkolnik, Vladimir
name: Seidel, Stephan T.
name: Wendrich, Thijs
name: Wenzlawski, André
name: Weps, Benjamin
name: Gaaloul, Naceur
name: Lüdtke, Daniel
name: Braxmaier, Claus
name: Ertmer, Wolfgang
name: Krutzik, Markus
name: Lämmerzahl, Claus
name: Peters, Achim
name: Schleich, Wolfgang P.
name: Sengstock, Klaus
name: Wicht, Andreas
name: Windpassinger, Patrick
name: Rasel, Ernst M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne matter-wave interferometry. Indeed, BECs enjoy a slowly expanding wave function, display a large spatial coherence and can be engineered and probed by optical techniques. On a sounding rocket, we explore matter-wave fringes of multiple spinor components of a BEC released in free fall employing light-pulses to drive Bragg processes and induce phase imprinting. The prevailing microgravity played a crucial role in the observation of these interferences which not only reveal the spatial coherence of the condensates but also allow us to measure differential forces. Our work establishes matter-wave interferometry in space with future applications in fundamental physics, navigation and Earth observation.
description: 7 pages, 3 figures
A simple conceptual model of abrupt glacial climate events
Creators: name: Braun, H.
name: Ganopolski, A.
name: Christl, M.
name: Chialvo, D. R.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Geophysics (physics.geo-ph)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: Here we use a very simple conceptual model in an attempt to reduce essential parts of the complex nonlinearity of abrupt glacial climate changes (the so-called Dansgaard-Oeschger events) to a few simple principles, namely (i) a threshold process, (ii) an overshooting in the stability of the system and (iii) a millennial-scale relaxation. By comparison with a so-called Earth system model of intermediate complexity (CLIMBER-2), in which the events represent oscillations between two climate states corresponding to two fundamentally different modes of deep-water formation in the North Atlantic, we demonstrate that the conceptual model captures fundamental aspects of the nonlinearity of the events in that model. We use the conceptual model in order to reproduce and reanalyse nonlinear resonance mechanisms that were already suggested in order to explain the characteristic time scale of Dansgaard-Oeschger events. In doing so we identify a new form of stochastic resonance (i.e. an overshooting stochastic resonance) and provide the first explicitly reported manifestation of ghost resonance in a geosystem, i.e. of a mechanism which could be relevant for other systems with thresholds and with multiple states of operation. Our work enables us to explicitly simulate realistic probability measures of Dansgaard-Oeschger events (e.g. waiting time distributions, which are a prerequisite for statistical analyses on the regularity of the events by means of Monte-Carlo simulations). We thus think that our study is an important advance in order to develop more adequate methods to test the statistical significance and the origin of the proposed glacial 1470-year climate cycle.
Αφηγήσεις γυναικών από την κοινότητα των Ρομά γύρω από ζητήματα γλώσσας, ταυτότητας, ένταξης.
Creators: name: Παναγιωτίδου, Χρυσάνθη Ιωάννη
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: Ρόμισσα
έμφυλη ταυτότητα
φυλετική ταυτότητα
γλώσσα
ένταξη- αποκλεισμός
Roma woman
gendered identity
racial identity
language
inclusion- exclusion

description: Το παρόν πόνημα πραγματεύεται τα γυναικεία ατομικά πεπρωμένα και τον τρόπο με τον οποίο ξετυλίγονται στο λόγο, εκκινώντας από την κοινή βάση έμφυλων και «φυλετικών» επιταγών. Ειδικότερα, κεντρικό ζητούμενο αποτέλεσε η διερεύνηση των αφηγήσεων γυναικών από την κοινότητα των Ρομά γύρω από ζητήματα γλώσσας, ταυτότητας και ένταξης. Γύρω από τις αφηγήσεις της Ρόμισσας, ανιχνεύονται οι λόγοι μέσα από τους οποίους συγκροτεί την υποκειμενικότητά της, οι τρόποι με τους οποίους κατασκευάζει τις πολλαπλές της ταυτότητες και τις διαχειρίζεται κατά τις διαδράσεις. Ανιχνεύονται οι τρόποι με τους οποίους υπερασπίζεται ή αποκρύπτει αυτές τις ταυτότητες κινούμενη σε δύο κόσμους στην κοινότητα της Ρομικής ομάδας και στο κυρίαρχο κοινωνικό πλαίσιο των “Μπαλαμών”. Η επιλογή της βιογραφικής προσέγγισης στην παρούσα εργασία δίνει το λόγο στα υποκείμενα, θέτοντας τον «εαυτό» ως υποκείμενο και αντικείμενο της έρευνας, ενώ αφηγήτριες και ερευνήτρια συν- κατασκευάζουν συνεχώς το νόημα της αφήγησης.
description: This study discusses the female individual destinies and the way which they unfold originating from the common basis of gendered and “racial” demands. In particular the study aims to research the narratives of women of the Roma community regarding to issues of language, identity and inclusion. Through the narratives of Roma women, the reasons establishing their subjectivity, as well as the ways in which their multiple identities are constructed and being managed through their interactions, are being detected. Τhe ways Roma women use to defend or conceal these identities while moving in two worlds in the community of Roma’s group and the dominant social context of “Balamos" are being detected. The choice of the biographical approach at the present paper gives voice to the subjects, putting the "self" as the subject and the object of research, while narrators and researcher continually co- construct the meaning of the narrative.
Probing cosmological parameters with the CMB: Forecasts from full Monte Carlo simulations
Creators: name: Perotto, Laurence
name: Lesgourgues, Julien
name: Hannestad, Steen
name: Tu, Huitzu
name: Wong, Yvonne Y. Y.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The Fisher matrix formalism has in recent times become the standard method for predicting the precision with which various cosmological parameters can be extracted from future data. This approach is fast, and generally returns accurate estimates for the parameter errors when the individual parameter likelihoods approximate a Gaussian distribution. However, where Gaussianity is not respected (due, for instance, to strong parameter degeneracies), the Fisher matrix formalism loses its reliability. In this paper, we compare the results of the Fisher matrix approach with those from Monte Carlo simulations. The latter method is based on the publicly available CosmoMC code, but uses synthetic realisations of data sets anticipated for future experiments. We focus on prospective cosmic microwave background (CMB) data from the Planck satellite, with or without CMB lensing information, and its implications for a minimal cosmological scenario with eight parameters and an extended model with eleven parameters. We show that in many cases, the projected sensitivities from the Fisher matrix and the Monte Carlo methods differ significantly, particularly in models with many parameters. Sensitivities to the neutrino mass and the dark matter fraction are especially susceptible to change.
description: 19 pages, 6 figures, our codes are available at http://lappweb.in2p3.fr/~perotto/FUTURCMB/home.html
The sum of the Betti numbers of smooth Hilbert schemes
Creators: name: Donato, Joseph
name: Lewis, Monica
name: Ryan, Tim
name: Udrenas, Faustas
name: Zhang, Zijian
Publisher: name: arXiv
Year: 2020
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14C05 (Primary), 14F25 (Secondary)

description: In this paper, we compute the sum of the Betti numbers for 6 of the 7 families of smooth Hilbert schemes over projective space.
description: 15 pages, 1 figure, Comments or suggestions welcome!
Αντιδράσεις 1,3-διπολικής κυκλοπροσθήκης του νιτριλοξειδίου της (6-πιπεριδιν-1-υλ-9Η-υλ)ακεταλδεΰδης με ακόρεστες αλκοόλες και ακόρεστους φωσφορικούς εστέρες και μελέτη της βιολογικής δράσης των προϊό
Creators: name: Μπαλαλάς, Θωμάς Δημητρίου
Publisher: name: Aristotle University of Thessaloniki
Year: 2014
Subjects: 1,3-διπολική κυκλοπροσθήκη
ισοξαζολίνη-ισοξαζόλιο
τροποποιημένος ομονουκλεοζίτης)
1,3-dipolar cycloaddition
isoxazoline-isoxazole
modified homonucleoside

description: Στην παρούσα εργασία, μελετήθηκε η σύνθεση τροποποιημένων ομο-Ν-νουκλεοζιτικών και νουκλεοτιδικών παραγώγων της πουρίνης, με 2-ισοξαζολίνες και ισοξαζόλια στην θέση του σακχάρου, μέσω της 1,3-διπολικής κυκλοπροσθήκης του νιτριλοξειδίου της (6-πιπεριδιν-1-υλ-9Η-πουριν-9-υλ)ακεταλδεΰδης με ακόρεστες αλκοόλες και ακόρεστους φωσφορικούς αιθυλεστέρες. Ο σχηματισμός του νιτριλοξειδίου πραγματοποιήθηκε in situ, είτε με την χρήση του Ν-χλώρο σουκινιμιδίου (NCS), είτε, σχεδόν ποσοτικά, με την χρήση υπερσθενών αντιδραστηρίων του ιωδίου (PIDA, PIFA). Εν συνεχεία, πραγματοποιήθηκε μία προκαταρτική in vitro βιολογική μελέτη της δράσης αυτών των ενώσεων στην αλληλεπίδραση με την ελεύθερη σταθερή ρίζα DPPH, στην αναστολή του ενζύμου λιποξυγονάση από σόγια και στην αναστολή της λιπιδικής υπεροξείδωσης που επάγεται από το AAPH.
description: In this study, we synthesized modified homo-N-nucleosides and nucleotides of purine, with 2-isoxazolines and isoxazoles in place of the sugar moiety. This procedure occurred through 1,3-dipolar cycloaddition reaction of the nitriloxide of the (6-piperidin-1-yl-9H-purin-9-yl)acetaldehyde with unsaturated alcohols and unsaturated phosphates. The nitriloxide formation was held in situ through the usage of N-cloro-succinimide (NCS) and, in almost quantitative yield, through the usage of hypervalent iodine reagents (PIDA, PIFA). Thereafter we held a preliminary in vitro study, of those derivatives, for their interaction with the stable free radical DPPH, inhibition of the enzyme lipoxygenase from soybean and inhibition of lipid peroxidation induced by AAPH.
Probing the superconducting condensate on a nanometer scale
Creators: name: Proslier, Th.
name: Kohen, A.
name: Noat, Y.
name: Cren, T.
name: Roditchev, D.
name: Sacks, W.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Superconductivity is a rare example of a quantum system in which the wavefunction has a macroscopic quantum effect, due to the unique condensate of electron pairs. The amplitude of the wavefunction is directly related to the pair density, but both amplitude and phase enter the Josephson current : the coherent tunneling of pairs between superconductors. Very sensitive devices exploit the superconducting state, however properties of the {\it condensate} on the {\it local scale} are largely unknown, for instance, in unconventional high-T$_c$ cuprate, multiple gap, and gapless superconductors. The technique of choice would be Josephson STS, based on Scanning Tunneling Spectroscopy (STS), where the condensate is {\it directly} probed by measuring the local Josephson current (JC) between a superconducting tip and sample. However, Josephson STS is an experimental challenge since it requires stable superconducting tips, and tunneling conditions close to atomic contact. We demonstrate how these difficulties can be overcome and present the first spatial mapping of the JC on the nanometer scale. The case of an MgB$_2$ film, subject to a normal magnetic field, is considered.
description: 7 pages, 6 figures
มุมมองของข้าราชการต่อการทำงานภายในหน่วยงานภายหลักการปฏิรูประบบราชการ
Creators: name: ณัฏฐพันธ์ เขจรนันทน์
Publisher: name: วารสารวิจัย มสด สาขามนุษยศาสตร์และสังคมศาสตร์
Year: 2551
Subjects: ข้าราชการ,การทำงาน,การปฏิรูประบบราชการ

description: 1, 4, วารสารวิจัย มสด สาขามนุษยศาสตร์และสังคมศาสตร์
Spectroscopic variations of the pulsating AP star γ equulei
Creators: name: Scott, Sandra L.
Publisher: name: University of British Columbia
Year: 2009

description: We investigated the radial velocity (RV) and light variations of the rapidly oscillating Ap (roAp) star γ Equ( HD 201601, HR 8097), with simultaneous (3.6m CFHT) spectroscopic and (UH 0.6m) photometric observations taken over 4 nights in August 1988. Despite lowamplitude detection limits on all nights, convincing RV and light oscillations were seen only on the last night, confirming amplitude modulation and/or mode evolutions noted by previous observers. The RV variations for the last night had a dominant frequency of 1.517 ± 0.01 mHz (P ~ 11.0 minutes) with an amplitude of 418 m s⁻¹, differing significantly from the 1.365 mHz (amplitude ~ 0.001 mag, P ~ 12.2 minutes) photometric frequency of the same night. We attribute the two frequencies to different modes observed almost equator on: the 1.5 mHz frequency to an (l=2, m=0) mode, and the 1.-4 mHz frequency to a dipole (l=1,m=0) mode. The former mode would have high RV amplitude but low photometric amplitude at this orientation, explaining the lack of photometric signal. This is the first time a non-dipole mode has been identified i n a roAp star. Based on our frequency data and those of other investigators plus the mode identifications above, we uniquely determine a fundamental p-mode spacing, Δv[sub o] ~ 60 μHz. Combined with stellar models, this value implies that γ Equ is near the main sequence, resolving an ambiguity about this star which has existed for almost a decade. Our results indicate it is critical that investigators use modes of the same degree l and orientation when determining the RV-to-light ratio (2K/Δm ) if it is to be used as a diagnostic of temperature and pulsational characteristics in roAp, stars.
Mixed Convective Heat Transfer Enhancement in a Ventilated Cavity by Flow Modulation via Rotating Plate
Creators: name: Islam, Aminul
name: Rony, Monoranjan Debnath
name: Islam, Mahmudul
name: Chowdhury, Emdadul Haque
name: Hasan, Mohammad Nasim
Publisher: name: arXiv
Year: 2020
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The present study numerically explores the mixed convection phenomena in a differentially heated ventilated square cavity with active flow modulation via a rotating plate. Forced convection flow in the cavity is attained by maintaining an external fluid flow through an opening at the bottom of the left cavity wall while leaving it through another opening at the right cavity wall. A counter-clockwise rotating plate at the center of the cavity acts as active flow modulator. Moving mesh approach is used for the rotation of the plate and the numerical solution is achieved using Arbitrary Lagrangian-Eulerian (ALE) finite element formulation with a quadrilateral discretization scheme. Transient parametric simulations have been performed for various frequency of the rotating plate for a fixed Reynolds number (Re) of 100 based on maximum inlet flow velocity while the Richardson number (Ri) is maintained at unity. Heat transfer performance has been evaluated in terms of spatially averaged Nusselt number and time-averaged Nusselt number along the heated wall. Power spectrum analysis in the frequency domain obtained from the fast Fourier transform (FFT) analysis indicates that thermal frequency and plate frequency start to deviate from each other at higher values of velocity ratio (> 4).
description: 36 pages, 14 figures
การกรองรูปภาพโดยใช้เทคนิคเรสโครไซต์เบอร์
Creators: name: ทรงพล นคเรศเรืองศักดิ์
Publisher: name: วารสารวิจัย มสด สาขาวิทยาศาสตร์และเทคโนโลยี
Year: 2557
Subjects: การกรองสัญญาณภาพ,เรสโครไซต์เบอร์,เรสโครไซต์มาร์ส

description: 2, 7, วารสารวิจัย มสด สาขาวิทยาศาสตร์และเทคโนโลยี
Hybrid quantum-classical algorithms and quantum error mitigation
Creators: name: Endo, Suguru
name: Cai, Zhenyu
name: Benjamin, Simon C.
name: Yuan, Xiao
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum computers can exploit a Hilbert space whose dimension increases exponentially with the number of qubits. In experiment, quantum supremacy has recently been achieved by the Google team by using a noisy intermediate-scale quantum (NISQ) device with over 50 qubits. However, the question of what can be implemented on NISQ devices is still not fully explored, and discovering useful tasks for such devices is a topic of considerable interest. Hybrid quantum-classical algorithms are regarded as well-suited for execution on NISQ devices by combining quantum computers with classical computers, and are expected to be the first useful applications for quantum computing. Meanwhile, mitigation of errors on quantum processors is also crucial to obtain reliable results. In this article, we review the basic results for hybrid quantum-classical algorithms and quantum error mitigation techniques. Since quantum computing with NISQ devices is an actively developing field, we expect this review to be a useful basis for future studies.
Scaling laws for the photo-ionisation cross section of two-electron atoms
Creators: name: Byun, Chang Woo
name: Choi, Nark Nyul
name: Lee, Min-Ho
name: Tanner, Gregor
Publisher: name: arXiv
Year: 2007
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: The cross sections for single-electron photo-ionisation in two-electron atoms show fluctuations which decrease in amplitude when approaching the double-ionisation threshold. Based on semiclassical closed orbit theory, we show that the algebraic decay of the fluctuations can be characterised in terms of a threshold law $σ\propto |E|^μ$ as $E \to 0_-$ with exponent $μ$ obtained as a combination of stability exponents of the triple-collision singularity. It differs from Wannier's exponent dominating double ionisation processes. The details of the fluctuations are linked to a set of infinitely unstable classical orbits starting and ending in the non-regularisable triple collision. The findings are compared with quantum calculations for a model system, namely collinear helium.
description: 4 pages, 1 figure
Current spinon-holon description of the one-dimensional charge-transfer insulator SrCuO2: Angle-resolved photoemission measurements
Creators: name: Koitzsch, A.
name: Borisenko, S. V.
name: Geck, J.
name: Zabolotnyy, V. B.
name: Knupfer, M.
name: Fink, J.
name: Ribeiro, P.
name: Buechner, B.
name: Follath, R.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We have investigated the low-energy electronic structure of the strongly correlated one-dimensional copper oxide chain compound SrCuO2 by angle resolved photoemission as a function of excitation energy. In addition to the prominent spinon-holon continuum we observe a peaklike and dispersive feature at the zone boundary. By fine-tuning the experimental parameters we are able to monitor the full holon branch and to directly measure the electronic hopping parameter with unprecedented accuracy.
description: 18 pages, 3 Figures
An Interferometric Imaging Survey of Red Supergiant Stars
Creators: name: Norris, Ryan
Publisher: name: Zenodo
Year: 2021
Subjects: Post main sequence cool stars
Interferometry
High Resolution Imaging
Red Supergiant Stars

description: Red supergiant stars (RSGs) are an end stage of massive star evolution. Among the notable behaviors of stars during this stage are their irregular and semi-regular variability and mass-loss. In order to better understand the sources of these phenomena, we collected high resolution optical interferometric observations of 17 RSGs using the Center for High Angular Resolution Astronomy (CHARA) Array at Mount Wilson between 2015 and 2016. Here, we present stellar diameters derived from these data. We comment on evidence of surface asymmetries on those stars for which we were able to obtain closure phases and present an example image for one of these objects. In addition, we have obtained near-contemporaneous spectroscopy of these stars using SpeX on the NASA InfraRed Telescope Facility (IRTF). We have developed libraries of synthetic spectra derived from spherical MARCS, PHOENIX, and SATLAS stellar atmospheres, and are currently working to derive fundamental stellar parameters with these data.
description: {"references": ["Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M.,Mantelet, G., & Andrae, R. 2018, AJ, 156, 58", "Keenan P. C., McNeil R. C., 1989,ApJS, 71, 245 (KM89)", "Levesque, E. M., Massey, P., Olsen, K. A. G., et al. 2005,ApJ,628, 973 (L05)", "Messineo, M., & Brown, A. G. A. 2019,AJ,158, 20 (M19)"]}
Chern-number spin Hamiltonians for magnetic nano-clusters by DFT methods
Creators: name: Strandberg, T. O.
name: Canali, C. M.
name: MacDonald, A. H.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Combining field-theoretical methods and ab-initio calculations, we construct an effective Hamiltonian with a single giant-spin degree of freedom, capable of the describing the low-energy spin dynamics of ferromagnetic metal nanoclusters consisting of up to a few tens of atoms. In our procedure, the magnetic moment direction of the Kohn-Sham SDFT wave-function is constrained by means of a penalty functional, allowing us to explore the entire parameter space of directions, and to extract the magnetic anisotropy energy and Berry curvature functionals. The average of the Berry curvature over all magnetization directions is a Chern number - a topological invariant that can only take on values equal to multiples of one half, representing the dimension of the Hilbert space of the effective spin system. The spin Hamiltonian is obtained by quantizing the classical anisotropy energy functional, after performing a change of variables to a constant Berry curvature space. The purpose of this article is to examine the impact of the topological effect from the Berry curvature on the low-energy total-spin-system dynamics. To this end, we study small transition metal clusters: Co$_{n}$ ($n=2,...,5$), Rh$_{2}$, Ni$_{2}$, Pd$_{2}$, Mn$_{x}$N$_{y}$, Co$_{3}$Fe$_{2}$.
description: 19 pages, 13 figures
An Alternative Approach to Holographic Dark Energy
Creators: name: Simpson, Fergus
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Here we consider a scenario in which dark energy is associated with the apparent area of a surface in the early universe. In order to resemble the cosmological constant at late times, this hypothetical reference scale should maintain an approximately constant physical size during an asymptotically de-Sitter expansion. This is found to arise when the particle horizon - anticipated to be significantly greater than the Hubble length - is approaching the antipode of a closed universe. Depending on the constant of proportionality, either the ensuing inflationary period prevents the particle horizon from vanishing, or it may lead to a sequence of "Big Rips".
description: 4 pages, 1 figure, revised version matches published version
Quasi-particle transitions in charge-phase qubits probed by rf oscillations
Creators: name: Könemann, J.
name: Zangerle, H.
name: Mackrodt, B.
name: Dolata, R.
name: Zorin, A. B.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We investigated transitions in Al charge-phase qubits of SQUID-configuration inductively coupled to an rf tank circuit that made it possible to read out the state by measuring the inductance of the qubit. Depending on the flux and charge bias and the amplitude of the rf oscillations we probed either the ground state or a dynamic change of the qubit states which we attributed to stochastic single quasi-particle tunneling onto and off the qubit island and exchange of energy with the qubit. Within this model, a selection rule for quasi-particle-induced transitions in the qubit is discussed.
description: 7 pages, 4 figures, major changes in the revised manuscript
The evolution of a circumplanetary disc with a dead zone
Creators: name: Chen, Cheng
name: Yang, Chao-Chin
name: Martin, Rebecca G.
name: Zhu, Zhaohuan
Publisher: name: arXiv
Year: 2020
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We investigate whether the regular Galilean satellites could have formed in the dead zone of a circumplanetary disc. A dead zone is a region of weak turbulence in which the magnetorotational instability (MRI) is suppressed, potentially an ideal environment for satellite formation. With the grid-based hydrodynamic code, FARGO3D, we examine the evolution of a circumplanetary disc model with a dead zone. Material accumulates in the dead zone of the disc leading to a higher total mass and but a similar temperature profile compared to a fully turbulent disc model. The tidal torque increases the rate of mass transport through the dead zone leading to a steady state disc with a dead zone that does not undergo accretion outbursts. We explore a range of disc, dead zone and mass inflow parameters and find that the maximum mass of the disc is around 0.001 MJ . Since the total solid mass of such a disc is much lower, we find that there is not sufficient material in the disc for in situ formation of the Galilean satellites and that external supplement is required.
description: 10 pages, 6 figures
On the relation of Thomas rotation and angular velocity of reference frames
Creators: name: Matolcsi, T.
name: Matolcsi, M.
name: Tasnádi, T.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In the extensive literature dealing with the relativistic phenomenon of Thomas rotation several methods have been developed for calculating the Thomas rotation angle of a gyroscope along a circular world line. One of the most appealing concepts, introduced in \cite{rindler}, is to consider a rotating reference frame co-moving with the gyroscope, and relate the precession of the gyroscope to the angular velocity of the reference frame. A recent paper \cite{herrera}, however, applies this principle to three different co-moving rotating reference frames and arrives at three different Thomas rotation angles. The reason for this apparent paradox is that the principle of \cite{rindler} is used for a situation to which it does not apply. In this paper we rigorously examine the theoretical background and limitations of applicability of the principle of \cite{rindler}. Along the way we also establish some general properties of {\it rotating reference frames}, which may be of independent interest.
description: 14 pages, 2 figures
Critical point symmetries in boson-fermion systems. The case of shape transition in odd nuclei in a multi-orbit model
Creators: name: Alonso, C. E.
name: Arias, J. M.
name: Vitturi, A.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We investigate phase transitions in boson-fermion systems. We propose an analytically solvable model (E(5/12)) to describe odd nuclei at the critical point in the transition from the spherical to $γ$-unstable behaviour. In the model, a boson core described within the Bohr Hamiltonian interacts with an unpaired particle assumed to be moving in the three single particle orbitals j=1/2,3/2,5/2. Energy spectra and electromagnetic transitions at the critical point compare well with the results obtained within the Interacting Boson Fermion Model, with a boson-fermion Hamiltonian that describes the same physical situation.
description: Phys. Rev. Lett. (in press)
$α$-Decay Lifetime in Superheavy Nuclei With $A>282$
Creators: name: Bhattacharya, Madhubrata
name: Gangopadhyay, G.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Nuclei with $A>282$ have been studied in the Relativistic Mean Field approach using the force FSU Gold and a zero range pairing interaction. The Euler-Lagrange equations have been solved in the co-ordinate space. Alpha nucleus potential has been constructed with the DDM3Y1 interaction, which has an exponential density dependence, in the double folding model using the nucleon densities in the daughter nucleus and the $α$ particle. Half lives of $α$ decay have been calculated for tunneling of the $α$ particle through the potential barrier in the WKB approximation and assuming a constant preformation probability. The resulting values agree well with experimental measurements.
description: To appear in Physical Rev. C
Electron Scattering in Thin GaAs Quantum Wires
Creators: name: Pozdnyakov, Dmitry
name: Galenchik, Vadim
name: Borzdov, Andrei
Publisher: name: arXiv
Year: 2006
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In this paper the scattering rates of electrons in thin free standing GaAs quantum wires in the electric quantum limit are calculated self-consistently taking into account the collisional broadening caused by scattering processes. The following mechanisms of scattering are considered: one-dimensional acoustic and polar optical phonons, surface roughness and ionized impurities. The non-parabolicity of electron energy spectrum is also taken into account.
description: 4 pages, 2 figures
A Noncommutative Version of the Minimal Supersymmetric Standard Model
Creators: name: Arai, Masato
name: Saxell, Sami
name: Tureanu, Anca
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A minimal supersymmetric standard model on noncommutative space-time (NC MSSM) is proposed. The model fulfils the requirements of noncommutative gauge invariance and absence of anomaly. The existence of supersymmetry with a scale of its breaking lower than the noncommutative scale is crucial in order to achieve a consistent gauge symmetry breaking.
description: 23 pages, some discussions refined. Final version, to appear in European Physical Journal C
Modular Hamiltonians for the massless Dirac field in the presence of a defect
Creators: name: Mintchev, Mihail
name: Tonni, Erik
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We study the massless Dirac field on the line in the presence of a point-like defect characterised by a unitary scattering matrix, that allows both reflection and transmission. Considering this system in its ground state, we derive the modular Hamiltonians of the subregion given by the union of two disjoint equal intervals at the same distance from the defect. The absence of energy dissipation at the defect implies the existence of two phases, where either the vector or the axial symmetry is preserved. Besides a local term, the densities of the modular Hamiltonians contain also a sum of scattering dependent bi-local terms, which involve two conjugate points generated by the reflection and the transmission. The modular flows of each component of the Dirac field mix the trajectory passing through a given initial point with the ones passing through its reflected and transmitted conjugate points. We derive the two-point correlation functions along the modular flows in both phases and show that they satisfy the Kubo-Martin-Schwinger condition. The entanglement entropies are also computed, finding that they do not depend on the scattering matrix.
description: 31 pages, 4 figures
Nonlinear Quantum Gravity
Creators: name: Svetlichny, George
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Nonlinear quantum mechanics at the Planck scale can produce nonlocal effects contributing to resolution of singularities, to cosmic acceleration, and modified black-hole dynamics, while avoiding the usual causality issues.
description: Resumed version of a talk given at the XXIV Workshop On Geometric Methods In Physics, 2005, Bialowieza, Poland
Age-relations for low-mass stars
Creators: name: , Kiman
name: , Faherty
name: , Cruz
name: , Gagné
name: , Angus
name: , Schmidt
name: , Mann
name: Gagliuffi, Bardalez
name: , Rice
Publisher: name: Zenodo
Year: 2021
Subjects: Cool Stars on the main sequence
Young stars

description: Stellar age is a key fundamental property for understanding the history, evolution, and future of stellar populations, the Milky Way, and exoplanets. However, age is extremely difficult to measure for individual stars. Low-mass stars, or M dwarfs, are the most numerous stars in the Galaxy, they have lifetimes longer than the current age of the Universe, and are likely to host the majority of Earth-like exoplanets. For this reason, these main sequence stars are ideal for studying the Milky Way and exoplanets properties in a wide range of ages. Ages of M dwarfs are especially difficult to estimate because methods used for solar-type stars break down as lower mass objects become fully convective. Empirical and statistical methods are required to constrain the ages of M dwarfs. I want to build a robust Bayesian algorithm to infer ages of M dwarfs from three age indicators: 1) Position in the color–magnitude diagram; 2) Magnetic activity, as indicated by H𝛼 emission line strength; 3) Full kinematics, taking advantage of Gaia DR2. I will present the age-calibrations I did of these age indicators, including the age-activity relation for H𝛼. I will show the results we obtained from our calibration of the age-activity relation, which indicates that H𝛼 strength decrease with age. I will also explain how we are going to use this relation to obtain precise estimation of M dwarf ages.
description: {"references": ["Bochanski et al. 2010, AJ, 139, 2679", "Dressing & Charbonneau 2015, ApJ, 807", "Gagn\u00e9 et al. 2018, ApJ, 856, 23"]}
Experimental investigation of vortex tube concepts
Creators: name: Camiré, Jean
Publisher: name: University of British Columbia
Year: 2009

description: The vortex tube is a very simple device which separates a compressed gas into a cold and a hot stream. The compressed gas is injected tangentially into the tube inlet by means of a nozzle. The gas develops a swirling motion in the tube. The gas leaving the tube near the wall will be warmer and that leaving the tube from the center will be cooler. Typically, with compressed air at 3 atm. and 290 K, it is possible to obtain a cold stream of T[sub]c = 260 K and a hot stream of T[sub]h = 330K. The general motivation of this thesis was to clarify the numerous assumptions on the vortex tube effect by the analysis of new measurements. Compared to previous studies, standard measurements of pressures and temperatures were improved by having the sensors very close to the tube. New measurements were obtained with the help of three novel techniques: i) Velocity profile measurements were done with a special pitot tube. ii) The vortex tube was tested at inlet pressures below atmospheric. iii) The spectrum of sound generated in the vortex tube was measured with the help of internally mounted microphones. The new data were compared to previous models, especially the two-streams model by Ahlborn et al. (1994), where the heating in the vortex tube is attributed to the conversion of kinetic energy into heat and the cooling to the reverse process. Due to the accuracy of the inlet pressure measurements, the new experiments showed unexpected high inlet velocities. In contradiction to Ahlborn's model, where the cold and hot streams have the same amount of energy, the vortex tube effect is explained in this work by an energy separation, in which the cold stream exits the tube with a lower energy than the hot stream.
title: Toward more holistic environmental governance of geothermal mineral extraction in Aotearoa New Zealand
Creators: name: Sajkowski, Lucjan
name: Bradshaw, Diane
name: Barr, A.
Publisher: name: GNS Science
Year: 2024

description: This report discusses environmental considerations and regulatory challenges associated with geothermal mineral extraction in New Zealand. It aims to initiate a dialogue on the potential impacts of mineral extraction from geothermal fluids and proposes a pathway for future research to measure and mitigate these impacts. The report acknowledges the significance of geothermal taonga (treasures) and haukainga (home and community) of Aotearoa New Zealand’s geothermal resources. The report highlights the geothermal systems in Aotearoa New Zealand, primarily located in the Taupo Volcanic Zone, as well as their historical and cultural importance to Maori people. It explores the past and present utilisation of geothermal resources for various purposes, including mineral extraction. The regulatory landscape surrounding geothermal mineral extraction is examined, with a focus on the Resource Management Act 1991 and the Crown Minerals Act 1991.Assessing the health of geothermal systems and associated taonga requires a holistic approach that considers factors such as water level, temperature, composition and aquifer pressure, as well as guardianship (kaitiakitanga) and spiritual (wairuatanga) values of Maori culture. The potential impacts of mineral extraction on geothermal systems are discussed, including changes in temperature and composition that can affect the appearance and biological characteristics of geothermal features. The need for monitoring and reporting to safeguard the environment is emphasised, along with the importance of involving local communities, including Maori, in the ongoing monitoring process. The report concludes by recommending the development of an environmental monitoring plan for geothermal mineral extraction that incorporates input from local communities, particularly Maori communities. It highlights the importance of collaboration, adaptive management, knowledge sharing, ethical considerations, robust policy and regulatory frameworks in ensuring the sustainable and responsible management of geothermal resources through sustainable resource use towards zero waste. (auths)
On vocabulary size of grammar-based codes
Creators: name: Debowski, Lukasz
Publisher: name: arXiv
Year: 2007
Subjects: subject: Information Theory (cs.IT)
subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences
subject: E.4

description: We discuss inequalities holding between the vocabulary size, i.e., the number of distinct nonterminal symbols in a grammar-based compression for a string, and the excess length of the respective universal code, i.e., the code-based analog of algorithmic mutual information. The aim is to strengthen inequalities which were discussed in a weaker form in linguistics but shed some light on redundancy of efficiently computable codes. The main contribution of the paper is a construction of universal grammar-based codes for which the excess lengths can be bounded easily.
description: 5 pages, accepted to ISIT 2007 and corrected
Evolution of Vocabulary on Scale-free and Random Networks
Creators: name: Kalampokis, Alkiviadis
name: Kosmidis, Kosmas
name: Argyrakis, Panos
Publisher: name: arXiv
Year: 2007
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: We examine the evolution of the vocabulary of a group of individuals (linguistic agents) on a scale-free network, using Monte Carlo simulations and assumptions from evolutionary game theory. It is known that when the agents are arranged in a two-dimensional lattice structure and interact by diffusion and encounter, then their final vocabulary size is the maximum possible. Knowing all available words is essential in order to increase the probability to ``survive'' by effective reproduction. On scale-free networks we find a different result. It is not necessary to learn the entire vocabulary available. Survival chances are increased by using the vocabulary of the ``hubs'' (nodes with high degree). The existence of the ``hubs'' in a scale-free network is the source of an additional important fitness generating mechanism.
description: 10 pages, 3 Figures, accepted in Physica A