cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Fluidization of granular media wetted by liquid $^4$He
Creators: name: Huang, K.
name: Sohaili, M.
name: Schröter, M.
name: Herminghaus, S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We explore experimentally the fluidization of vertically agitated PMMA spheres wetted by liquid $^4$He. By controlling the temperature around the $λ$ point we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization ($Γ_c$) shows a steep increase close to the saturation of the vapor pressure in the sample cell. For helium II wetting, $Γ_c$ starts to increase at about 75% saturation, indicating that capillary bridges are enhanced by the superflow of unsaturated helium film. Above saturation, $Γ_c$ enters a plateau regime where the capillary force between particles is independent of the bridge volume. The plateau value is found to vary with temperature and shows a peak at 2.1 K, which we attribute to the influence of the specific heat of liquid helium.
description: 4 pages, 3 figures, Accepted by Phys. Rev. E as a rapid communication
Stories from Bones: 3D Printing bones for Public Engagement and Making Educational Resources
Creators: name: Hampshire Cultural Trust
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Ferromagnetism in armchair graphene nanoribbon heterostructures
Creators: name: Almeida, P. A.
name: Sousa, L. S.
name: Schmidt, Tome M.
name: Martins, G. B.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We study the properties of flat-bands that appear in a heterostructure composed of strands of different widths of graphene armchair nanoribbons. One of the flat-bands is reminiscent of the one that appears in pristine armchair nanoribbons and has its origin in a quantum mechanical destructive interference effect, dubbed `Wannier orbital states' by Lin et al. in Phys. Rev. B 79, 035405 (2009). The additional flat-bands found in these heterostructures, some reasonably closer to the Fermi level, seem to be generated by a similar interference process. After doing a thorough tight-binding analysis of the band structures of the different kinds of heterostructures, focusing in the properties of the flat-bands, we use Density Functional Theory to study the possibility of magnetic ground states when placing, through doping, the Fermi energy close to the different flat-bands. Our DFT results confirmed the expectation that these heterostructures, after being appropriately hole-doped, develop a ferromagnetic ground state that seems to require, as in the case of pristine armchair nanoribbons, the presence of a dispersive band crossing the flat-band. In addition, we found a remarkable agreement between the tight-binding and DFT results for the charge density distribution of the so-called Wannier orbital states.
description: 13 pages, 18 figures
Post ex and festivals
Creators: name: Grace, Nancy
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Lewis and Berry phases for a gravitational wave interacting with a quantum harmonic oscillator
Creators: name: Sen, Soham
name: Dutta, Manjari
name: Gangopadhyay, Sunandan
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this work, we consider a gravitational wave interacting with a quantum harmonic oscillator in the transverse-traceless gauge. We take the gravitational wave to be carrying the signatures of both plus and cross polarization at first. We then try to obtain a suitable form of the Lewis invariant using the most general form possible while considering only quadratic order contributions from both position and momentum variables. In order to progress further, we then drop the cross terms obtaining a separable Hamiltonian in terms of the first and the second spatial coordinates. We then obtain two Lewis invariants corresponding to each separable parts of the entire Hamiltonian of the system. Using both Lewis invariants, one can obtain two Ermakov-Pinney equations, from which we finally obtain the corresponding Lewis phase and eventually the Berry phase for the entire system. Finally, we obtain some explicit expressions of the Berry phase for a plane polarized gravitational wave with different choices of the harmonic oscillator frequency.
description: About to appear in Physica Scripta (16 pages LATEX)
Forma Urbis: where archaeology meets people
Creators: name: Caporicci, Irene
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
The globular cluster AM 4: yet another young globular associated with the Sgr Dwarf Spheroidal galaxy?
Creators: name: Carraro, Giovanni
Publisher: name: arXiv
Year: 2009
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The complete census of globular clusters formerly belonging to the Sgr dSph and now deposited into the Galactic halo is an important contribution to our comprehension of the evolution and disruption of this dwarf galaxy. We investigate in this study the possibility that the poorly known "old" globular AM 4 might be associated with the Sagittarius dwarf galaxy, and at the same time provide more solid estimate of its basic parameters. New high quality BVI photometry is presented, from which an improved Color Ma gnitude Diagram is constructed, and estimates of age and distance are then derived. The distance and Galactic position are finally investigated in details. AM~4 is found to be a low luminosity (M$_V$=-1.82) cluster undergoing strong tidal stress by the Milky Way and on the verge to be dissolved. Besides, and at odds with previous suggestions, we provide evidences that AM 4 is indeed young, with an age around 9 Gyrs (as Terzan~7), but somewhat more metal poor ([Fe/H=-0.97]). AM~4 is located at 33$_{-4}^{+3}$ kpc from the Sun, in a direction and at distance not totally incompatible with the Sgr dSph stream. Although we significantly improved our knowledge of AM 4, further studies are encouraged to obtain radial velocity and metallicity to d emonstrate more firmly (or deny) the association to Sgr
description: 23 pages, 8 eps figures, in press in the Astronomical Journal
Green Book IPAI
Creators: name: Keudell, Felix Von
name: Suttrup, Francisca
name: Funder, Fiona
name: Ower, Stephan
name: :Unav
Publisher: name: Fraunhofer-Gesellschaft
Year: 2021
Subjects: Nachhaltigkeit
Künstliche Intelligenz
Nachhaltiges Bauen
Nachhaltige Architektur
Nachhaltige Bauwirtschaft
Baden-Württemberg
Innovationspark KI

description: Mit dem Innovation Park Artificial Intelligence (IPAI) entsteht am Standort Heilbronn auf einer Gesamtfläche von ca. 23 Hektar ein europaweit führendes Innovationsökosystem aus Wirtschaft, Wissenschaft und intermediären Akteuren, welches das internationale Vertrauen in KI-Produkte »Made in Baden-Württemberg« nachhaltig stärken soll. Dabei soll ein bedeutendes Technologiezentrum sowie ein gigantisches Reallabor realisiert werden, das neue Maßstäbe setzt - sowohl im Hinblick auf die anwendungsorientierte KI-Entwicklung als auch auf den nachhaltigen Umgang mit Daten durch alle involvierten Akteure. Das Thema Nachhaltigkeit hat dabei viele Facetten. Das Spektrum reicht von Fragen der ethischen Verantwortung bei der Entwicklung künstlicher Intelligenz über den Einsatz von KI-Verfahren zur Lösung von Nachhaltigkeitsproblemen bis hin zum ökologisch nachhaltigen Betrieb von Gebäuden und Rechenzentren. Das Fraunhofer-Institut für Arbeitswirtschaft und Organisation IAO hat das Green Book IPAI als Nachhaltigkeitskonzept erstellt. Gemeinsam mit dem Kooperationspartner bicg haben die Forschenden mit Expertinnen und Experten gesprochen, Impulse gesammelt und systematisch erfasst, welche Nachhaltigkeitsschwerpunkte vergleichbare Großprojekte gegenwärtig setzen oder bislang gesetzt haben. Das hier vorliegende Green Book IPAI fasst die Erkenntnisse der Gespräche als Ideen und Anregungen zusammen und richtet sich an ein breites Publikum.
The Generalized Uncertainty Principle and Quantum Gravity Phenomenology
Creators: name: Ali, Ahmed Farag
name: Das, Saurya
name: Vagenas, Elias C.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this article we examine a Generalized Uncertainty Principle which differs from the Heisenberg Uncertainty Principle by terms linear and quadratic in particle momenta, as proposed by the authors in an earlier paper. We show that this affects all Hamiltonians, and in particular those which describe low energy experiments. We discuss possible observational consequences. Further, we also show that this indicates that space may be discrete at the fundamental level.
description: 3 pages. Talk given by SD at the 12th Marcel Grossmann conference (Paris, July, 2009)
Diving into the Past: Public Archaeology and SCUBA Stewardship
Creators: name: Grinnan, Nicole
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Dipolar field effect on microwave oscillation in a domain wall spin-valve
Creators: name: Matsushita, Katsuyoshi
name: Sato, Jun
name: Imamura, Hiroshi
Publisher: name: arXiv
Year: 2009
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We examined dipolar field effects on the microwave generation in the domain wall spin-valve by solving simultaneously the Landau-Lifshitz-Gilbert and Zhang-Levy-Fert diffusion equations. By numerically analyzing dipolar field dependence, we showed that the microwave generation needs the dipole-dipole interaction for a 180$^\circ$ domain wall and the amplitude of the microwave voltage signal depends strongly on the exchange length. In order to design a microwave generator using the domain wall spin-valve with high efficiency, we propose that the materials with short exchange length are preferred.
description: 4 pages, 4 figures
Energy Beamforming for RF Wireless Power Transfer with Dynamic Metasurface Antennas
Creators: name: Azarbahram, Amirhossein
name: Lopez, Onel L. A.
name: Souza, Richard D.
name: Zhang, Rui
name: Latva-Aho, Matti
Publisher: name: arXiv
Year: 2023
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Radio frequency (RF) wireless power transfer (WPT) is a promising technology for charging the Internet of Things. Practical RF-WPT systems usually require energy beamforming (EB), which can compensate for the severe propagation loss by directing beams toward the devices. The EB flexibility depends on the transmitter architecture, existing a trade-off between cost/complexity and degrees of freedom. Thus, simpler architectures such as dynamic metasurface antennas (DMAs) are gaining attention. Herein, we consider an RF-WPT system with a transmit DMA for meeting the energy harvesting requirements of multiple devices and formulate an optimization problem for the minimum-power design. First, we provide a mathematical model to capture the frequency-dependant signal propagation effect in the DMA architecture. Next, we propose a solution based on semi-definite programming and alternating optimization. Results show that a DMA-based structure can outperform a fully-digital implementation and that the required transmit power decreases with the antenna array size, while it increases and remains almost constant with frequency in DMA and FD, respectively.
description: Accepted for publication in IEEE Wireless Communications Letters
Multiple Parton Interactions, top--antitop and W+4j production at the LHC
Creators: name: Maina, Ezio
Publisher: name: arXiv
Year: 2009
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The expected rate for Multiple Parton Interactions (MPI) at the LHC is large. This requires an estimate of their impact on all measurement foreseen at the LHC while opening unprecendented opportunities for a detailed study of these phenomena. In this paper we examine the MPI background to top-antitop production, in the semileptonic channel, in the early phase of data taking when the full power of $b$--tagging will not be available. The MPI background turns out to be small but non negligible, of the order of 20% of the background provided by W+4j production through a Single Parton Interaction. We then analyze the possibility of studying Multiple Parton Interactions in the W+4j channel, a far more complicated setting than the reactions examined at lower energies. The MPI contribution turns out to be dominated by final states with two energetic jets which balance in transverse momentum, and it appears possible, thanks to the good angular resolution of ATLAS and CMS, to separate the Multiple Parton Interactions contribution from Single Parton Interaction processes. The large cross section for two jet production suggests that also Triple Parton Interactions (TPI) could provide a non negligible contribution. Our preliminary analysis suggests that it might be indeed possible to investigate TPI at the LHC.
description: Typos fixed. Published in JHEP
Scaling relations for globular cluster systems in early-type galaxies. II. Is there an environmental dependence?
Creators: name: De Bortoli, Bruno J.
name: Caso, Juan P.
name: Ennis, Ana I.
name: Bassino, Lilia P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The current properties of globular cluster systems (GCSs) are the result of the evolution experienced by their host galaxies, which shape the richness of the GCS as well as its spatial distribution, among other features. We carry out an analysis of the projected radial distribution of globular clusters for a sample of almost 30 early-type galaxies (ETGs) of intermediate and low luminosity, located in cluster environments (Virgo, Fornax and Coma). We also include in the study six ETGs, for which the parameters of their GCS radial profiles are publicly available. The final analysis is performed on an enlarged sample (~ 100 GCSs), by adding the GCSs of ETGs from our previous paper (Paper I). Scaling relations involving different parameters of the GCSs are obtained for the whole sample and complement those obtained in Paper I. Several of such relations point to a second-order dependence on the environmental density. Finally, the results are analysed in the literature context.
Digging and Discovering ... on Campus
Creators: name: MSU Campus Archaeology
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Urban Gardening in Medieval Cities. In a Modern Library.
Creators: name: Goodson, Caroline
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Economical (k,m)-threshold controlled quantum teleportation
Creators: name: SaiToh, Akira
name: Rahimi, Robabeh
name: Nakahara, Mikio
Publisher: name: arXiv
Year: 2009
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study a (k,m)-threshold controlling scheme for controlled quantum teleportation. A standard polynomial coding over GF(p) with prime p > m-1 needs to distribute a d-dimensional qudit with d >= p to each controller for this purpose. We propose a scheme using m qubits (two-dimensional qudits) for the controllers' portion, following a discussion on the benefit of a quantum control in comparison to a classical control of a quantum teleportation.
description: 11 pages, 2 figures, v2: minor revision, discussions improved, an equation corrected in procedure (A) of section 4.3, v3: major revision, protocols extended, citations added, v4: minor grammatical revision, v5: minor revision, discussions extended
The many researchers of the GeoSatReSeArch Lab: high tech archaeology!
Creators: name: Armstrong, Kayt
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
NANOGrav spectral index $γ=3$ from melting domain walls
Creators: name: Babichev, E.
name: Gorbunov, D.
name: Ramazanov, S.
name: Samanta, R.
name: Vikman, A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We discuss cosmic domain walls described by a tension red-shifting with the expansion of the Universe. These melting domain walls emit gravitational waves with the low-frequency spectral shape $Ω_{gw}\propto f^{2}$ corresponding to the spectral index $γ=3$ favoured by the recent NANOGrav 15 yrs data. We discuss a concrete high-energy physics scenario leading to such a melting domain wall network in the early Universe. This scenario involves a feebly coupled scalar field, which can serve as a promising dark matter candidate. We identify parameters of the model matching the gravitational wave characteristics observed in the NANOGrav data. The dark matter mass is pushed to the ultra-light range below $10^{-11}-10^{-12}\,\text{eV}$ which is accessible through planned observations thanks to the effects of superradiance of rotating black holes.
description: 7 revtex pages, 1 figure; added references and appendix with the calculation of gravitational wave spectrum; matches version accepted in PRD
On the nature of the Schmid transition in a resistively shunted Josephson junction
Creators: name: Daviet, Romain
name: Dupuis, Nicolas
Publisher: name: arXiv
Year: 2023
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study the phase diagram of a resistively shunted Josephson junction (RSJJ) in the framework of the boundary sine-Gordon model. Using the non-perturbative functional renormalization group (FRG) we find that the transition is not controlled by a single fixed point but by a line of fixed points, and compute the continuously varying critical exponent $ν$. We argue that the conductance also varies continuously along the transition line. In contrast to the traditional phase diagram of the RSJJ -- an insulating ground state when the shunt resistance $R$ is larger than $R_q=h/(2e)^2$ and a superconducting one when $R
description: 15 pages, 15 figures ; v2 closer to published version
Archival Research in Historical Archaeology
Creators: name: Krause, Grace
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
An anti-Schwarzshild solution: wormholes and scalar-tensor solutions
Creators: name: Mimoso, José P.
name: Lobo, Francisco S. N.
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We investigate a static solution with an hyperbolic nature, characterised by a pseudo-spherical foliation of space. This space-time metric can be perceived as an anti-Schwarzschild solution, and exhibits repulsive features. It belongs to the class of static vacuum solutions termed "a degenerate static solution of class A". In the present work we review its fundamental features, discuss the existence of generalised wormholes, and derive its extension to scalar-tensor gravity theories in general.
description: 3 pages, contribution to the proceedings of the Spanish Relativity Meeting-ERE2009
The Metal-Silicate Partitioning of Carbon During Earth's Accretion and its Distribution in the Early Solar System
Creators: name: Blanchard, I.
name: Rubie, D. C.
name: Jennings, E. S.
name: Franchi, I. A.
name: Zhao, X.
name: Petitgirard, S.
name: Miyajima, N.
name: Jacobson, S. A.
name: Morbidelli, A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: Carbon is an essential element for the existence and evolution of life on Earth. Its abundance in Earth's crust and mantle (the Bulk Silicate Earth, BSE) is surprisingly high given that carbon is strongly siderophile (metal-loving) at low pressures and temperatures, and hence should have segregated almost completely into Earth's core during accretion. Estimates of the concentration of carbon in the BSE lie in the range 100-260 ppm and are much higher than expected based on simple models of core-mantle differentiation. Here we show through experiments at the putative conditions of Earth's core formation (49-71 GPa and 3600-4000 K) that carbon is significantly less siderophile at these conditions than at the low pressures ($\leq$13 GPa) and temperatures ($\leq$2500 K) of previous large volume press studies, but at least an order of magnitude more siderophile than proposed recently based on an experimental approach that is similar to ours. Using our new data along with previously published results, we derive a new parameterization of the pressure-temperature dependence of the metal-silicate partitioning of carbon. We apply this parameterization in a model that combines planet formation and core-mantle differentiation that is based on astrophysical N-body accretion simulations. Because differentiated planetesimals were almost completely depleted in carbon due to sublimation at high temperatures, almost all carbon in the BSE was added by the accretion of fully-oxidized carbonaceous chondrite material from the outer solar system. Carbon is added to the mantle continuously throughout accretion and its concentration reaches values within the BSE range (e.g. 140$\pm$40 ppm) at the end of accretion. The corresponding final core and bulk Earth carbon concentrations are 1270$\pm$300 ppm and 495$\pm$125 ppm respectively.
description: Supplementary material included in pdf
A multigroup approach to delayed prion production
Creators: name: Adimy, Mostafa
name: Chekroun, Abdennasser
name: Pujo-Menjouet, Laurent
name: Sensi, Mattia
Publisher: name: arXiv
Year: 2023
Subjects: subject: Dynamical Systems (math.DS)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Mathematics
subject: FOS: Biological sciences
subject: 34K20, 37G99, 37N25, 92B05, 92C20

description: We generalize the model proposed in [Adimy, Babin, Pujo-Menjouet, \emph{SIAM Journal on Applied Dynamical Systems} (2022)] for prion infection to a network of neurons. We do so by applying a so-called \emph{multigroup approach} to the system of Delay Differential Equations (DDEs) proposed in the aforementioned paper. We derive the classical threshold quantity $\mathcal{R}_0$, \textit{i.e.} the basic reproduction number, exploiting the fact that the DDEs of our model qualitatively behave like Ordinary Differential Equations (ODEs) when evaluated at the Disease Free Equilibrium. We prove analytically that the disease naturally goes extinct when $\mathcal{R}_0<1$, whereas it persists when $\mathcal{R}_0>1$. We conclude with some selected numerical simulations of the system, to illustrate our analytical results.
description: 21 pages, 11 figures
Why I volunteered in archaeology
Creators: name: Archaeology, Allen
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Atlantic weather regimes and poleward heat transport by transient eddies
Creators: name: Ruggieri, Paolo
Publisher: name: Zenodo
Year: 2019

description: Transport of heat by transient atmospheric eddies is a key component of the heat budget of the Arctic and high latitude regions. While transport in the midlatitudes is known to be modulated by large scale low frequency flow regimes, little is known about the link between heat flux in the polar cap and midlatitude circulation regimes. Recent studies suggest that heat and moisture transport into the pole happens in “bursts” that are associated with atmospheric blocking. While the picture is evolving, a systematic assessment is still lacking.

In this study we investigate the relationship between the poleward heat transport by atmospheric transient eddies and North Atlantic weather regimes in reanalysis data.

Weather regimes are estimated via clustering methods, a jet latitude index and a blocking index. Heat transport is defined as advection of moist static energy and the transient component has been computed for selected frequency bands between the midlatitude baroclinic life cycle and the seasonal range.

Results show that transient eddy heat flux is substantially modulated by midlatitude weather regimes on a regional scale also in polar regions. On a zonal mean sense, the phases of the North Atlantic Oscillation do not change significantly the synoptic heat flux, whereas Scandinavian blocking and Atlantic Ridge are associated with an intensification.

The relationship between extreme events of strong heat flux and circulation regimes is also assessed and the analysis indicates a fundamental role of blocking in the North Atlantic sector.

The implications of our findings for sub-seasonal predictability and systematic errors in coupled models are discussed. Applications of the proposed approach to seasonal forecast systems and multi-model frameworks are suggested.
The gauge technique
Creators: name: Zhang, Ruibin
Publisher: name: University Of Tasmania
Year: 2023

description: The gauge technique is a nonperturbative scheme for solving the field equations in gauge theories. This thesis is devoted towards understanding and extending the approximation procedures in the gauge technique. In the past the lowest order approximation consisted in only taking into account the longitudinal amplitudes; we have succeeded in generalizing it to incorporate transverse corrections for arbitrary covariant gauges in the context of electrodynamics. As a consequence the nonperturbative results are exact to order e 4 , and the gauge invariance of the vacuum polarization is correspondingly restored by the refined technique. Contrary to common belief, we have also found that the radiative corrections to the gluon propagator lie solely in the contributions of transverse vertices. Thus in principle the lowest order gauge technique is not readily applicable to the gluon sector of quantum chromodynamics. Finally we have shown that in two-dimensional electrodynamics (massless Schwinger model) the gauge technique produces exact results because one is able to solve the vector and axial Ward-Takahashi identities uniquely. In this way it is possible to obtain the complete solution for any linear gauge at any temperature.
High-order finite element method for atomic structure calculations
Creators: name: Čertík, Ondřej
name: Pask, John E.
name: Fernando, Isuru
name: Goswami, Rohit
name: Sukumar, N.
name: Collins, Lee A.
name: Manzini, Gianmarco
name: Vackář, Jiří
Publisher: name: arXiv
Year: 2023
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: We introduce \texttt{featom}, an open source code that implements a high-order finite element solver for the radial Schrödinger, Dirac, and Kohn-Sham equations. The formulation accommodates various mesh types, such as uniform or exponential, and the convergence can be systematically controlled by increasing the number and/or polynomial order of the finite element basis functions. The Dirac equation is solved using a squared Hamiltonian approach to eliminate spurious states. To address the slow convergence of the $κ=\pm1$ states due to divergent derivatives at the origin, we incorporate known asymptotic forms into the solutions. We achieve a high level of accuracy ($10^{-8}$ Hartree) for total energies and eigenvalues of heavy atoms such as uranium in both Schrödinger and Dirac Kohn-Sham solutions. We provide detailed convergence studies and computational parameters required to attain commonly required accuracies. Finally, we compare our results with known analytic results as well as the results of other methods. In particular, we calculate benchmark results for atomic numbers ($Z$) from 1 to 92, verifying current benchmarks. We demonstrate significant speedup compared to the state-of-the-art shooting solver \texttt{dftatom}. An efficient, modular Fortran 2008 implementation, is provided under an open source, permissive license, including examples and tests, wherein particular emphasis is placed on the independence (no global variables), reusability, and generality of the individual routines.
description: 30 pages, 3 tables, 6 figures, accepted in Elsevier's Computer Physics Communications
Heritage as Future Making Practice
Creators: name: May, Sarah
Publisher: name: Archaeology Data Service
Year: 2015

description: This resource is a single blog post created as part of the Day of Archaeology initiative. The Day of Archaeology project aimed to provide a window into the daily lives of archaeologists from all over the world. The project asked people working, studying or volunteering in the archaeological world to participate in a 'Day of Archaeology' each year by recording their day and sharing it through text, images or video on the Day of Archaeology blog.
The project asked anyone with a personal, professional or voluntary interest in archaeology to get involved, and help highlight the reasons why archaeology is vital to protect the past and inform our futures. The resulting Day of Archaeology project archive demonstrates the wide variety of work the archaeological profession undertakes day-to-day across the globe, and helps to raise public awareness of the relevance and importance of archaeology to the modern world.
The first ever Day of Archaeology was held in 2011 and, since then, the project had thousands of archaeologists take part in the event, from those working in the field through to specialists working in laboratories and behind computers. The last Day of Archaeology was on Friday 28th July 2017.
Regional Differences in Information Privacy Concerns After the Facebook-Cambridge Analytica Data Scandal
Creators: name: González-Pizarro, Felipe
name: Figueroa, Andrea
name: López, Claudia
name: Aragon, Cecilia
Publisher: name: arXiv
Year: 2022
Subjects: subject: Social and Information Networks (cs.SI)
subject: Computation and Language (cs.CL)
subject: Computers and Society (cs.CY)
subject: FOS: Computer and information sciences
subject: K.4; I.2

description: While there is increasing global attention to data privacy, most of their current theoretical understanding is based on research conducted in a few countries. Prior work argues that people's cultural backgrounds might shape their privacy concerns; thus, we could expect people from different world regions to conceptualize them in diverse ways. We collected and analyzed a large-scale dataset of tweets about the #CambridgeAnalytica scandal in Spanish and English to start exploring this hypothesis. We employed word embeddings and qualitative analysis to identify which information privacy concerns are present and characterize language and regional differences in emphasis on these concerns. Our results suggest that related concepts, such as regulations, can be added to current information privacy frameworks. We also observe a greater emphasis on data collection in English than in Spanish. Additionally, data from North America exhibits a narrower focus on awareness compared to other regions under study. Our results call for more diverse sources of data and nuanced analysis of data privacy concerns around the globe.
Standing on the shoulders of giants: Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids
Creators: name: Lyra, W.
name: Johansen, A.
name: Klahr, H.
name: Piskunov, N.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Centimeter and meter sized solid particles in protoplanetary disks are trapped within long lived high pressure regions, creating opportunities for collapse into planetesimals and planetary embryos. We study the accumulations in the stable Lagrangian points of a giant planet, as well as in the Rossby vortices launched at the edges of the gap it carves. We employ the Pencil Code, tracing the solids with a large number of interacting Lagrangian particles, usually 100,000. For particles of 1 cm to 10 cm radii, gravitational collapse occurs in the Lagrangian points in less than 200 orbits. For 5 cm particles, a 2 Earth mass planet is formed. For 10 cm, the final maximum collapsed mass is around 3 Earth masses. The collapse of the 1 cm particles is indirect, following the timescale of depletion of gas from the tadpole orbits. In the edges of the gap vortices are excited, trapping preferentially particles of 30 cm radii. The rocky planet that is formed is as massive as 17 Earth masses, constituting a Super-Earth. By using multiple particle species, we find that gas drag modifies the streamlines in the tadpole region around the classical L4 and L5 points. As a result, particles of different radii have their stable points shifted to different locations. Collapse therefore takes longer and produces planets of lower mass. Three super-Earths are formed in the vortices, the most massive having 4.4 Earth masses. We conclude that a Jupiter mass planet can induce the formation of other planetary embryos in the outer edge of its gas gap. Trojan Earth mass planets are readily formed, and although not existing in the solar system, might be common in the exoplanetary zoo.
description: 18 pages, 10 figures. Accepted by A&A
Strong quantum nonlocality in $N$-partite systems
Creators: name: Shi, Fei
name: Ye, Zuo
name: Chen, Lin
name: Zhang, Xiande
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A set of multipartite orthogonal quantum states is strongly nonlocal if it is locally irreducible for every bipartition of the subsystems [Phys. Rev. Lett. 122, 040403 (2019)]. Although this property has been shown in three-, four- and five-partite systems, the existence of strongly nonlocal sets in $N$-partite systems remains unknown when $N\geq 6$. In this paper, we successfully show that a strongly nonlocal set of orthogonal entangled states exists in $(\mathbb{C}^d)^{\otimes N}$ for all $N\geq 3$ and $d\geq 2$, which for the first time reveals the strong quantum nonlocality in general $N$-partite systems. For $N=3$ or $4$ and $d\geq 3$, we present a strongly nonlocal set consisting of genuinely entangled states, which has a smaller size than any known strongly nonlocal orthogonal product set. Finally, we connect strong quantum nonlocality with local hiding of information as an application.