cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Measures and amalgamation properties in ω-categorical structures
Creators: name: Marimon, Paolo
Publisher: name: Imperial College London
Year: 2023

description: This thesis explores the relationship between measures and amalgamation properties in simple ω-categorical structures. In particular, we prove that a stronger version of the independence theorem is satisfied by simple ω-categorical structures where a formula forks over ∅ if and only if it is assigned measure zero by every invariant Keisler measure. This will be used to show that certain classes of simple ω-categorical Hrushovski constructions have non-forking (over ∅) formulas which are assigned measure zero by every invariant Keisler measure. Until a recent article of Chernikov, Hrushovski, Kruckman, Krupinski, Moconja, Pillay and Ramsey, it was unknown whether there were any simple structures where forking and being universally measure zero disagreed. We give the first simple ω-categorical example of this phenomenon. We also study ω-categorical MS-measurable structures in the sense of Macpherson and Steinhorn. Our main results show that various classes of ω-categorical Hrushovski constructions and the generic tetrahedron-free 3-hypergraph fail to be MS-measurable in spite of being supersimple of finite rank. These examples answer negatively a question of Elwes and Macpherson on whether being supersimple ω-categorical of finite SU-rank implies being MS-measurable. Our results on ω-categorical Hrushovski constructions complement previous work of Evans who had given a counterexample to this question. Unlike Evans’ example, our Hrushovski constructions may satisfy independent n-amalgamation for all n over finite algebraically closed sets. We also develop tools to study the measures of higher amalgamations in MS-measurable structures. With these, we show that the generic tetrahedron-free 3-hypergraph is not MS-measurable giving the first one-based ω-categorical supersimple example of this phenomenon and showing that this structure cannot be elementarily equivalent to the ultraproduct of an asymptotic class of finite structures. Finally, we show that the universal homogeneous two-graph has a unique invariant Keisler measure not induced by any invariant type.
Software implementation of the SNOW 3G Generator on iOS and Android platforms
Creators: name: Molina-Gil, Jezabel
name: Caballero-Gil, Pino
name: Caballero-Gil, Cándido
name: Fúster-Sabater, Amparo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: The standard for wireless communication of high-speed data in mobile phones and data terminals, called LTE (Long-Term Evolution) and marketed as 4G/LTE, is quickly being adopted worldwide. The security of this type of communication is a crucial factor mainly due to its mobile and wireless nature. This work includes a practical analysis of the SNOW 3G generator used to protect the confidentiality and integrity in LTE communications. In particular, several techniques to perform multiplications and LFSR operations have been studied and implemented on both iOS and Android platforms. The evaluation of those implementations led to some conclusions that could be used to improve the efficiency of future implementations of the standard.
Beyond Special Relativity at second order
Creators: name: Carmona, J. M.
name: Cortes, J. L.
name: Relancio, J. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The study of generic, non-linear, deformations of Special Relativity parametrized by a high-energy scale $M$, which was carried out at first order in $M$ in Phys.Rev. D86, 084032 (2012), is extended to second order. This can be done systematically through a ('generalized') change of variables from momentum variables that transform linearly. We discuss the different perspectives on the meaning of the change of variables, obtain the coefficients of modified composition laws and Lorentz transformations at second order, and work out how $κ$-Poincaré, the most commonly used example in the literature, is reproduced as a particular case of the generic framework exposed here.
description: 19 pages
A plausible link between the asteroid 21 Lutetia and CH carbonaceous chondrites
Creators: name: Moyano-Cambero, Carles E.
name: Trigo-Rodríguez, Josep M.
name: Llorca, Jordi
name: Fornasier, Sonia
name: Barucci, Maria A.
name: Rimola, Albert
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: A crucial topic in planetology research is establishing links between primitive meteorites and their parent asteroids. In this study we investigate the feasibility of a connection between asteroids similar to 21 Lutetia, encountered by the Rosetta mission in July 2010, and the CH3 carbonaceous chondrite Pecora Escarpment 91467 (PCA 91467). Several spectra of this meteorite were acquired in the ultraviolet to near-infrared (0.3 to 2.2 μm) and in the mid-infrared to thermal infrared (2.5 to 30.0 μm or 4000 to ~333 cm^-1), and they are compared here to spectra from the asteroid 21 Lutetia. There are several similarities in absorption bands and overall spectral behavior between this CH3 meteorite and 21 Lutetia. Considering also that the bulk density of Lutetia is similar to that of CH chondrites, we suggest that this asteroid could be similar, or related to, the parent body of these meteorites, if not the parent body itself. However, the apparent surface diversity of Lutetia pointed out in previous studies indicates that it could simultaneously be related to other types of chondrites. Future discovery of additional unweathered CH chondrites could provide deeper insight in the possible connection between this family of metal-rich carbonaceous chondrites and 21 Lutetia or other featureless, possibly hydrated high-albedo asteroids.
description: 26 pages, 7 figures and 2 tables, Meteoritics and Planetary Science, manuscript #2225 (2016)
Tailoring Accelerating Beams in Phase Space
Creators: name: Wen, Yuanhui
name: Chen, Yujie
name: Zhang, Yanfeng
name: Chen, Hui
name: Yu, Siyuan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: An appropriate design of wavefront will enable light fields propagating along arbitrary trajectories thus forming accelerating beams in free space. Previous ways of designing such accelerating beams mainly rely on caustic methods, which start from diffraction integrals and only deal with two-dimensional fields. Here we introduce a new perspective to construct accelerating beams in phase space by designing the corresponding Wigner distribution function (WDF). We find such a WDF-based method is capable of providing both the initial field distribution and the angular spectrum in need by projecting the WDF into the real space and the Fourier space respectively. Moreover, this approach applies to the construction of both two- and three-dimensional fields, greatly generalizing previous caustic methods. It may therefore open up a new route to construct highly-tailored accelerating beams and facilitate applications ranging from particle manipulation and trapping to optical routing as well as material processing.
description: 8 pages, 6 figures
How to build vehicular ad-hoc networks on smartphones
Creators: name: Caballero-Gil, Pino
name: Caballero-Gil, Cándido
name: Molina-Gil, Jezabel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: Vehicular ad-hoc networks have been defined in the literature as communications networks that allow disseminating information among vehicles to help to reduce traffic accidents and congestions. The practical deployment of such networks has been delayed mainly due to economic and technical issues. This paper describes a new software application to detect traffic incidents and exchange information about them, using only smartphones, without any central authority or additional equipment. Both road safety and communication security have been taken into account in the application design. On the one hand, the interface has been designed to avoid distractions while driving because it operates automatically and independently of the driver, through voice prompts. On the other hand, communication security, which is essential in critical wireless networks, is provided through the protection of attributes such as authenticity, privacy, integrity and non-repudiation. All this is achieved without increasing the price of vehicles and without requiring the integration of new devices neither in vehicles nor on roads. The only prerequisite is to have a smartphone equipped with Wi-Fi connectivity and GPS location in each vehicle. The proposed application has been successfully validated both in large-scale NS-2 simulations and in small-scale real tests to detect traffic congestions and empty parking spaces.
Active particles, ratchets and their field theories
Creators: name: Zhen, Zigan
Publisher: name: Imperial College London
Year: 2023

description: This thesis aims to address problems in active matter by employing techniques in both stochastic processes and statistical field theories. It is mainly divided into two parts: first, applications of stochastic processes to find the entropy production of var- ious exactly solvable models and solve the dynamics of a Run-and-Tumble particle in a piecewise linear potential, and second, applications of field theories to find the optimal shape for maximising currents of a Run-and-Tumble particle perturbatively and probing the particle identities using different field theories. In Chapter 1, I de- rive various methods and results from stochastic processes that are used in the rest of the thesis. In Chapter 2, I present a self-contained review of entropy production and calculate it from first principles for various exactly solvable models. In Chap- ter 3, I solve the steady-state dynamics of a Run-and-Tumble particle in a piece- wise linear ratchet and calculate various other quantities such as particle current, entropy production and mean first passage time. In Chapter 4, I derive and present Doi-Peliti field theory and response field theory which are used in the rest of the the- sis. In Chapter 5, I present a method of solving the probability distribution perturba- tively and finding the optimal shape of the potential that maximises the probability current for a Run-and-Tumble particle using Doi-Peliti field theory. In Chapter 6, I identify the mechanism where particle entity is enforced in the context of the Doi- Peliti field theory of a diffusive particle and the response field theory that is derived from Dean’s equation.
Valuation of patents in emerging economies: a renewal model-based study of Indian patents
Creators: name: Danish, Mohd Shadab
name: Ranjan, Pritam
name: Sharma, Ruchi
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: This study uses patent renewal information to estimate private value of patents by technology and ownership status. Patent value refers to the economic reward that the inventor extracts from the patent by making, using or selling an invention. Thus, we measure the value of patent right (private value of patent) from the patentee perspective. Our empirical analysis comprises of 555 patents with application year during 1999 to 2002. The term of these patents either ended in 2018 or lapsed due to non-payment of renewal fee. We model renewal decision of patentee as ordered probit where patent renewal fee increases with the age of patent. Variables such as patent family size, technological scope, number of inventors and grant lag are used as explanatory variables in the corresponding regression. Hence, this paper combines the patentee renewal decision along with patents characteristics and renewal cost schedule to estimate the initial rent distribution. We find that a large number of patents expire at an early stage leaving few patents with high value corroborating the results of studies using European, American and Chinese data. As expected, certain technology class patents enjoy high valuation.
Black Holes, Information Loss and the Measurement Problem
Creators: name: Okon, Elias
name: Sudarsky, Daniel
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The information loss paradox is often presented as an unavoidable consequence of well-established physics. However, in order for a genuine paradox to ensue, not-trivial assumptions about, e.g., quantum effects on spacetime, are necessary. In this work we will be explicit about these additional, speculative assumptions required. We will also sketch a map of the available routes to tackle the issue, highlighting the, often overlooked, commitments demanded of each alternative. In particular, we will display the strong link between black holes, the issue of information loss and the measurement problem.
description: 14 pages, 3 figures
Characterizing the structure of protein-protein interaction networks
Creators: name: Zea, Allan A.
name: Rueda-Toicen, Antonio
Publisher: name: arXiv
Year: 2016
Subjects: subject: Molecular Networks (q-bio.MN)
subject: FOS: Biological sciences

description: Network theorists have developed methods to characterize the complex interactions in natural phenomena. The structure of the network of interactions between proteins is important in the field of proteomics, and has been subject to intensive research in recent years, as scientists have become increasingly capable and interested in describing the underlying structure of interactions in both normal and pathological biological processes. In this paper, we survey the graph-theoretic characterization of protein-protein interaction networks (PINs) in terms of structural features, and discuss its possible applications in biomedical research. We also perform a brief revision of network theory's classical literature and discuss modern statistical and computational techniques to describe the structure of PINs
description: 10 pages, 3 figures. Conference: CIMENICS XIII at Caracas, Venezuela, 2016
Revisiting Chaplygin gas cosmologies with the recent observations of high-redshfit quasars
Creators: name: Zheng, Jie
name: Cao, Shuo
name: Lian, Yujie
name: Liu, Tonghua
name: Liu, Yuting
name: Zhu, Zong-Hong
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In this paper, we use the latest observations of quasars covering the redshift range of $0.04
description: 17 pages, 9 figures
Preferential concentration of inertial sub-kolmogorov particles. The roles of mass loading of particles, Stokes and Reynolds numbers
Creators: name: Sumbekova, Sholpan
name: Cartellier, Alain
name: Aliseda, Alberto
name: Bourgoin, Mickael
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Turbulent flows laden with inertial particles present multiple open questions and are a subject of great interest in current research. Due to their higher density compared to the carrier fluid, inertial particles tend to form high concentration regions, i.e. clusters, and low concentration regions, i.e. voids, due to the interaction with the turbulence. In this work, we present an experimental investigation of the clustering phenomenon of heavy sub-Kolmogorov particles in homogeneous isotropic turbulent flows. Three control parameters have been varied over significant ranges: $Re_λ \in [170 - 450]$, $St\in [0.1 - 5]$ and volume fraction $ϕ_v\in [2\times 10^{-6} - 2\times 10^{-5}]$. The scaling of clustering characteristics, such as the distribution of Voronoï areas and the dimensions of cluster and void regions, with the three parameters are discussed. In particular, for the polydispersed size distributions considered here, clustering is found to be enhanced strongly (quasi-linearly) by $Re_λ$ and noticeably (with a square-root dependency) with $ϕ_v$, while the cluster and void sizes, scaled with the Kolmogorov lengthscale $η$, are driven primarily by $Re_λ$. Cluster length $\sqrt{\langle A_c \rangle}$ scales up to $\approx 100 η$, measured at the highest $Re_λ$, while void length $\sqrt{\langle A_v \rangle}$ scaled also with $η$ is typically two times larger ($\approx 200 η$). The lack of sensitivity of the above characteristics to the Stokes number lends support to the "sweep-stick" particle accumulation scenario. The non-negligible influence of the volume fraction, however, is not considered by that model and can be connected with collective effects.
A Measurement Test Set for ALMA Band 9 Amplifiers
Creators: name: López-Fernández, Isaac
name: Gallego, Juan Daniel
name: Diez, Carmen
Publisher: name: Zenodo
Year: 2009
Subjects: Low Noise amplifier, Cryogenic noise measurements, cold attenuator method, ALMA

description: A description of the test set used for the measurements of ALMA band 9 4-12 GHz cryogenic amplifiers is presented. Special attention is given to the error sources in the cryogenic noise measurements following the cold attenuator method.
Radiation from an off-centred rotating dipole in vacuum
Creators: name: Pétri, J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: When a neutron star forms, after the collapse of its progenitor, a strong magnetic field survives in its interior. This magnetic topology is usually assumed to be well approximated by a dipole located right at the centre of the star. However, there is no particular reason why this dipole should be attached to this very special point. A slight shift from the stellar centre could have strong implications for the surrounding electromagnetic field configuration leading to clear observational signatures. We study the effect of the most general off-centred dipole anchored in the neutron star interior. Exact analytical solutions are given in vacuum outside the star to any order of accuracy in the small parameter $ε= d/R$, where $d$ is the displacement of the dipole from the stellar centre and $R$ the neutron star radius. As a simple diagnostic of this decentred dipole, the spin-down luminosity and the torque exerted on its crust are computed to the lowest leading order in~$ε$. Results are compared to earlier works and a discussion on repercussions on pulsar braking index and multi-wavelength light curves is proposed.
description: Accepted for publication in MNRAS
Estimation of Uncertainty in Noise Measurements Using Monte Carlo Analysis
Creators: name: J. D. Gallego
name: J. L. Cano
Publisher: name: Zenodo
Year: 2009
Subjects: Monte Carlo method, Cryogenic noise measurements, Low Noise Amplifier

description: Analysis of uncertainties and calibration errors in room and cryogenic temperature noise measurements of low noise amplifiers. The Monte Carlo Method is followed and applied to several practical examples. MathCAD and Mathlab software to perform the calculations was developed and is available.
In-situ real-space imaging of crystal surface reconstruction dynamics via electron microscopy
Creators: name: Xu, Weizong
name: Bowes, Preston C.
name: Grimley, Everett D.
name: Irving, Douglas L.
name: LeBeau, James M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Crystal surfaces are sensitive to the surrounding environment, where atoms left with broken bonds reconstruct to minimize surface energy. In many cases, the surface can exhibit chemical properties unique from the bulk. These differences are important as they control reactions and mediate thin film growth. This is particularly true for complex oxides where certain terminating crystal planes are polar and have a net dipole moment. For polar terminations, reconstruction of atoms on the surface is the central mechanism to avoid the so called polar catastrophe. This adds to the complexity of the reconstruction where charge polarization and stoichiometry govern the final surface in addition to standard thermodynamic parameters such as temperature and partial pressure. Here we present direct, in-situ determination of polar SrTiO3 (110) surfaces at temperatures up to 900 C using cross-sectional aberration corrected scanning transmission electron microscopy (STEM). Under these conditions, we observe the coexistence of various surface structures that change as a function of temperature. As the specimen temperature is lowered, the reconstructed surface evolves due to thermal mismatch with the substrate. Periodic defects, similar to dislocations, are found in these surface structures and act to relieve stress due to mismatch. Combining STEM observations and electron spectroscopy with density functional theory, we find a combination of lattice misfit and charge compensation for stabilization. Beyond the characterization of these complex reconstructions, we have developed a general framework that opens a new pathway to simultaneously investigate the surface and near surface regions of single crystals as a function of environment.
Performance of Interoperator Fixed-Mobile Network Sharing
Creators: name: Szcześniak, Ireneusz
name: Pach, Andrzej R.
name: Woźna-Szcześniak, Bożena
Publisher: name: arXiv
Year: 2016
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: We evaluate the downstream performance of our novel interoperator fixed-mobile network sharing, in which operators exchange data in their access networks. We propose a performance evaluation algorithm, and report credible performance evaluation results obtained for 204600 randomly-generated passive optical networks. We show that with the proposed sharing, operators can increase their access network performance even twofold with software-defined upgrades, and with no or minimal new hardware required.
description: submitted to a conference
Thermodynamics of polarized relativistic matter
Creators: name: Kovtun, Pavel
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We give the free energy of equilibrium relativistic matter subject to external gravitational and electromagnetic fields, to one-derivative order in the gradients of the external fields. The free energy allows for a straightforward derivation of bound currents and bound momenta in equilibrium. At leading order, the energy-momentum tensor admits a simple expression in terms of the polarization tensor. Beyond the leading order, electric and magnetic polarization vectors are intrinsically ambiguous. The physical effects of polarization, such as the correlation between the magneto-vortically induced surface charge and the electro-vortically induced surface current, are not ambiguous.
description: 26 pages
Solvability of a class of mean-field BSDEs with quadratic growth
Creators: name: Hao, Tao
name: Wen, Jiaqiang
name: Xiong, Jie
Publisher: name: arXiv
Year: 2022
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60H10, 60H30

description: In this paper, we study the multi-dimensional mean-field backward stochastic differential equations (BSDEs, for short) with quadratic growth. Under small terminal value, the existence and uniqueness are proved for the multi-dimensional situation when the generator f(t,Y,E[Y],Z,E[Z]) is of quadratic growth with respect to the last four items, using some new methods. Besides, a kind of comparison theorem is obtained.
description: 15 pages. arXiv admin note: text overlap with arXiv:1909.10846
Prospects for PWNe and SNRs science with the ASTRI mini-array of pre-production small-sized telescopes of the Cherenkov Telescope Array
Creators: name: Burtovoi, A.
name: Zampieri, L.
name: Giuliani, A.
name: Bigongiari, C.
name: Di Pierro, F.
name: Stamerra, A.
name: Collaboration, the ASTRI
name: Consortium, the CTA
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The development and construction of the Cherenkov Telescope Array (CTA) opens up new opportunities for the study of very high energy (VHE, E>100 GeV) sources. As a part of CTA, the ASTRI project, led by INAF, has one of the main goals to develop one of the mini-arrays of CTA pre-production telescopes, proposed to be installed at the CTA southern site. Thanks to the innovative dual-mirror optical design of its small-sized telescopes, the ASTRI mini-array will be characterized by a large field of view, an excellent angular resolutioerrorn and a good sensitivity up to energies of several tens of TeV. Pulsar wind nebulae, along with Supernova Remnants, are among the most abundant sources that will be identified and investigated, with the ultimate goal to move significantly closer to an understanding of the origin of cosmic rays (CR). As part of the ongoing effort to investigate the scientific capabilities for both CTA as a whole and the ASTRI mini-array, we performed simulations of the Vela X region. We simulated its extended VHE gamma-ray emission using the results of the detailed H.E.S.S. analysis of this source. We estimated the resolving capabilities of the diffuse emission and the detection significance of the pulsar with both CTA as a whole and the ASTRI mini-array. Moreover with these instruments it will be possible to observe the high-energy end of SNRs spectrum, searching for particles with energies near the cosmic-rays "knee" (E~10^15 eV). We simulated a set of ASTRI mini-array observations for one young and an evolved SNRs in order to test the capabilities of this instrument to discover and study PeVatrons on the Galactic plane.
description: 6 pages, 4 figures, 1 table. In Proceedings of the 2016 Heidelberg Symposium on High Energy Gamma-Ray Astronomy
Explaining unusual line profiles of SN 2006gy
Creators: name: Chugai, Nikolai
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Origin of enigmatic line profiles of extremely luminous type IIn supernova SN~2006gy on day 96 is explored. Among conceivable possibilities the most preferred is the model that suggests holes in the optically thick cool dense shell (CDS). The line radiation emitted at the inner side of the opaque CDS escapes through the holes thus producing unusual line profile with the emission shifted redward. The holes could emerge as a result of a vigorous Rayleigh-Taylor instability leading to the CDS fragmentation. The model light curve with the CDS fragmentation is shown to be consistent with the SN~2006gy bolometric light curve.
description: MNRAS, accepted
Parallel QR Factorization of Block Low-Rank Matrices
Creators: name: Apriansyah, M. Ridwan
name: Yokota, Rio
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: Mathematical Software (cs.MS)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: G.1.3; G.1.2; G.4; D.1.3

description: We present two new algorithms for Householder QR factorization of Block Low-Rank (BLR) matrices: one that performs block-column-wise QR, and another that is based on tiled QR. We show how the block-column-wise algorithm exploits BLR structure to achieve arithmetic complexity of $\mathcal{O}(mn)$, while the tiled BLR-QR exhibits $\mathcal{O}(mn^{1.5})$ complexity. However, the tiled BLR-QR has finer task granularity that allows parallel task-based execution on shared memory systems. We compare the block-column-wise BLR-QR using fork-join parallelism with tiled BLR-QR using task-based parallelism. We also compare these two implementations of Householder BLR-QR with a block-column-wise Modified Gram-Schmidt (MGS) BLR-QR using fork-join parallelism, and a state-of-the-art vendor-optimized dense Householder QR in Intel MKL. For a matrix of size 131k $\times$ 65k, all BLR methods are more than an order of magnitude faster than the dense QR in MKL. Our methods are also robust to ill-conditioning and produce better orthogonal factors than the existing MGS-based method. On a CPU with 64 cores, our parallel tiled Householder and block-column-wise Householder algorithms show a speedup of 50 and 37 times, respectively.
description: 23 pages, 12 figures
Magnetic avalanches in granular ferromagnets: Thermal activated collective behavior
Creators: name: Chern, Gia-Wei
Publisher: name: arXiv
Year: 2016
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We present a numerical study on the thermal activated avalanche dynamics in granular materials composed of ferromagnetic clusters embedded in a non-magnetic matrix. A microscopic dynamical simulation based on the reaction-diffusion process is developed to modeling the magnetization process of such systems. The large-scale simulations presented here explicitly demonstrate inter-granular collective behavior induced by thermal activation of spin tunneling. In particular, we observe an intriguing criticality controlled by the rate of energy dissipation. We show that thermal activated avalanches can be understood in the framework of continuum percolation and the emergent dissipation induced criticality is in the universality class of three-dimensional percolation transition. Implications of these results to the phase-separated states of colossal magnetoresistance materials and other artificial granular magnetic systems are also~discussed.
description: 10 pages, 7 figures, special issue of J. Phys. Condens. Matter
Weak antilocalization effect and triply degenerate state in Cu-doped CaAuAs
Creators: name: Malick, Sudip
name: Ghosh, Arup
name: Barman, Chanchal K.
name: Alam, Aftab
name: Hossain, Z.
name: Mandal, Prabhat
name: Nayak, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The effect of 50\% Cu doping at the Au site in the topological Dirac semimetal CaAuAs is investigated through electronic band structure calculations, electrical resistivity, and magnetotransport measurements. Electronic structure calculations a suggest broken-symmetry-driven topological phase transition from the Dirac to triple-point state in CaAuAs via alloy engineering. The electrical resistivity of both the CaAuAs and CaAu$_{0.5}$Cu$_{0.5}$As compounds shows metallic behavior. Nonsaturating quasilinear magnetoresistance (MR) behavior is observed in CaAuAs. On the other hand, MR of the doped compound shows a pronounced cusplike feature in the low-field regime. Such behavior of MR in CaAu$_{0.5}$Cu$_{0.5}$As is attributed to the weak antilocalization (WAL) effect. The WAL effect is analyzed using different theoretical models, including the semiclassical $\sim\sqrt{B}$ one which accounts for the three-dimensional WAL and modified Hikami-Larkin-Nagaoka model. Strong WAL effect is also observed in the longitudinal MR, which is well described by the generalized Altshuler-Aronov model. Our study suggests that the WAL effect originates from weak disorder and the spin-orbit coupled bulk state. Interestingly, we have also observed the signature of chiral anomaly in longitudinal MR, when both current and field are applied along the $c$ axis. The Hall resistivity measurements indicate that the charge conduction mechanism in these compounds is dominated by the holes with a concentration $\sim$10$^{20}$ cm$^{-3}$ and mobility $\sim 10^2$ cm$^2$ V$^{-1}$ S$^{-1}$.
Axiomatic nonextensive statistics at NICA energies
Creators: name: Tawfik, Abdel Nasser
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We discuss the possibility of implementing axiomatic nonextensive statistics, where it is conjectured that the phase-space volume determines the (non)extensive entropy, on the particle production at NICA energies. Both Boltzmann-Gibbs and Tsallis statistics are very special cases of this generic (non)extensivity. We conclude that the lattice thermodynamics is {\it ab initio} extensive and additive and thus the nonextensive approaches including Tsallis statistics categorically are not matching with them, while the particle production, for instance the particle ratios at various center-of-mass energies, is likely a nonextensive process but certainly not of Tsallis type. The resulting freezeout parameters, the temperature and the chemical potentials, are approximately compatible with the ones deduced from Boltzmann-Gibbs statistics.
description: 6 pages, 2 figures, accepted for publication in EPJA Topical Issue "NICA White Paper" (17th Feb. 2016)
Proceedings of the 2016 Workshop on Semantic Spaces at the Intersection of NLP, Physics and Cognitive Science
Creators: name: Kartsaklis, Dimitrios
name: Lewis, Martha
name: Rimell, Laura
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computation and Language (cs.CL)
subject: Artificial Intelligence (cs.AI)
subject: Category Theory (math.CT)
subject: Quantum Physics (quant-ph)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: This volume contains the Proceedings of the 2016 Workshop on Semantic Spaces at the Intersection of NLP, Physics and Cognitive Science (SLPCS 2016), which was held on the 11th of June at the University of Strathclyde, Glasgow, and was co-located with Quantum Physics and Logic (QPL 2016). Exploiting the common ground provided by the concept of a vector space, the workshop brought together researchers working at the intersection of Natural Language Processing (NLP), cognitive science, and physics, offering them an appropriate forum for presenting their uniquely motivated work and ideas. The interplay between these three disciplines inspired theoretically motivated approaches to the understanding of how word meanings interact with each other in sentences and discourse, how diagrammatic reasoning depicts and simplifies this interaction, how language models are determined by input from the world, and how word and sentence meanings interact logically. This first edition of the workshop consisted of three invited talks from distinguished speakers (Hans Briegel, Peter Gärdenfors, Dominic Widdows) and eight presentations of selected contributed papers. Each submission was refereed by at least three members of the Programme Committee, who delivered detailed and insightful comments and suggestions.
Geometry and design of origami bellows with tunable response
Creators: name: Reid, Austin
name: Lechenault, Frederic
name: Rica, Sergio
name: Adda-Bedia, Mokhtar
Publisher: name: arXiv
Year: 2016
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Origami folded cylinders (origami bellows) have found increasingly sophisticated applications in space flight and medicine. In spite of this interest, a general understanding of the mechanics of an origami folded cylinder has been elusive. With a newly developed set of geometrical tools, we have found an analytic solution for all possible cylindrical rigid-face states of both Miura-ori and triangular tessellations. Although an idealized bellows in both of these families may have two allowed rigid-face configurations over a well-defined region, the corresponding physical device, limited by nonzero material thickness and forced to balance hinge and plate-bending energy, often cannot stably maintain a stowed configuration. We have identified the parameters that control this emergent bistability, and have demonstrated the ability to design and fabricate bellows with tunable deployability.
description: 21 pages, 12 figures
Informational and Causal Architecture of Continuous-time Renewal and Hidden Semi-Markov Processes
Creators: name: Marzen, Sarah E.
name: Crutchfield, James P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Information Theory (cs.IT)
subject: Statistics Theory (math.ST)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: We introduce the minimal maximally predictive models (ε-machines) of processes generated by certain hidden semi-Markov models. Their causal states are either hybrid discrete-continuous or continuous random variables and causal-state transitions are described by partial differential equations. Closed-form expressions are given for statistical complexities, excess entropies, and differential information anatomy rates. We present a complete analysis of the ε-machines of continuous-time renewal processes and, then, extend this to processes generated by unifilar hidden semi-Markov models and semi-Markov models. Our information-theoretic analysis leads to new expressions for the entropy rate and the rates of related information measures for these very general continuous-time process classes.
description: 16 pages, 7 figures; http://csc.ucdavis.edu/~cmg/compmech/pubs/ctrp.htm
Innovation diffusion equations on correlated scale-free networks
Creators: name: Bertotti, M. L.
name: Brunner, J.
name: Modanese, G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Social and Information Networks (cs.SI)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: We introduce a heterogeneous network structure into the Bass diffusion model, in order to study the diffusion times of innovation or information in networks with a scale-free structure, typical of regions where diffusion is sensitive to geographic and logistic influences (like for instance Alpine regions). We consider both the diffusion peak times of the total population and of the link classes. In the familiar trickle-down processes the adoption curve of the hubs is found to anticipate the total adoption in a predictable way. In a major departure from the standard model, we model a trickle-up process by introducing heterogeneous publicity coefficients (which can also be negative for the hubs, thus turning them into stiflers) and a stochastic term which represents the erratic generation of innovation at the periphery of the network. The results confirm the robustness of the Bass model and expand considerably its range of applicability.
description: 13 pages, 5 figures
NGC 2440 : A morpho-kinematical model
Creators: name: Lago, Paulo J. A.
name: Costa, Roberto D. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: This work describes the modelling of the 3D structure and position-velocity (P-V) diagrams of NGC 2440, a well known planetary nebula, aiming to describe the morphology of this object, specially its core. We have used high resolution spectra and P-V diagrams to reproduce the 3D structure of the nebula using SHAPE, a software that allows 3D modelling. HST high angular resolution images were used as reference to the model. The observational data point to a segmented core, and the simulations confirm this assumption; the best model for the nebula is a torus segmented in three pieces. The simulated P-V diagrams agree with the observations. We suggest that the torus was torn apart by interaction with the surrounding medium, either as winds or the radiation field. For the two bipolar lobes, orientation angles to the plane of the sky of $27\pm$5 and $-5\pm3$ degrees, respectively for the bipolar components with PA of 85 and 35 degrees, were derived. No additional bipolar lobes were required to model the observed features of NGC 2440. A distance of $1.8 \pm 0.5$ kpc was derived for the nebula using our velocity field for the toroidal structure. These results are the first derived for NGC 2440 from modelling in a 3D environment.
description: 16 pages, 8 figures
Binding energies of molecular solids from fragment and periodic approaches
Creators: name: Hofierka, J.
name: Klimes, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We calculate binding energies of four molecular solids using the Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory (MP2). We obtain the energies within many-body expansion (MBE) as well as using periodic boundary conditions (PBC) to compare both approaches. The systems we study are methane, carbon dioxide, ammonia, and methanol. We use tight convergence settings to obtain the binding energies with a high precision, we estimate the uncertainties to be only few tenths of percent. We discuss several issues that affect the quality of the results and which need to be considered to reach high precision for both MBE and within PBC. For example, HF as well as MP2 energies within PBC benefited from the use of real-space Coulomb cut-off technique, the convergence of energies within MBE was improved by modifying the order of summation. Finally, numerical noise made the evaluation of some of the MBE contributions difficult and the effect was reduced by using smaller basis sets for the less critical terms.
Star forming activity in the H II regions associated with IRAS 17160-3707 complex
Creators: name: Nandakumar, G.
name: Veena, V. S.
name: Vig, S.
name: Tej, A.
name: Ghosh, S. K.
name: Ojha, D. K.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present a multiwavelength investigation of star formation activity towards the southern H II regions associated with IRAS 17160-3707, located at a distance of 6.2 kpc with a bolometric luminosity of 830000 Lsun.The ionised gas distribution and dust clumps in the parental molecular cloud are examined in detail using measurements at infrared, submillimeter and radio wavelengths.The radio continuum images at 1280 and 610 MHz obtained using Giant Metrewave Radio Telescope reveal the presence of multiple compact sources as well as nebulous emission.At submillimeter wavelengths, we identify seven dust clumps and estimate their physical properties like temperature: 24 - 30 K, mass: 300 - 4800 Msun and luminosity: 900 - 31700 Lsun using modified blackbody fits to the spectral energy distributions between 70 and 870 um.We find 24 young stellar objects in the mid-infrared, with few of them coincident with the compact radio sources.The spectral energy distributions of young stellar objects have been fitted by the Robitaille models and the results indicate that those having radio compact sources as counterparts host massive objects in early evolutionary stages with best fit age <= 0.2 Myr.We compare the relative evolutionary stages of clumps using various signposts such as masers, ionised gas, presence of young stellar objects and infrared nebulosity and find six massive star forming clumps and one quiescent clump.Of the former, five are in a relatively advanced stage and one in an earlier stage.
description: 54 pages, 23 figures, Accepted for publication in The Astronomical Journal
Explosive transitions in complex networks' structure and dynamics: percolation and synchronization
Creators: name: Boccaletti, S.
name: Almendral, J. A.
name: Guan, S.
name: Leyva, I.
name: Liu, Z.
name: Sendiña-Nadal, I.
name: Wang, Z.
name: Zou, Y.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: FOS: Physical sciences

description: Percolation and synchronization are two phase transitions that have been extensively studied since already long ago. A classic result is that, in the vast majority of cases, these transitions are of the second-order type, i.e. continuous and reversible. Recently, however, explosive phenomena have been reported in com- plex networks' structure and dynamics, which rather remind first-order (discontinuous and irreversible) transitions. Explosive percolation, which was discovered in 2009, corresponds to an abrupt change in the network's structure, and explosive synchronization (which is concerned, instead, with the abrupt emergence of a collective state in the networks' dynamics) was studied as early as the first models of globally coupled phase oscillators were taken into consideration. The two phenomena have stimulated investigations and de- bates, attracting attention in many relevant fields. So far, various substantial contributions and progresses (including experimental verifications) have been made, which have provided insights on what structural and dynamical properties are needed for inducing such abrupt transformations, as well as have greatly enhanced our understanding of phase transitions in networked systems. Our intention is to offer here a monographic review on the main-stream literature, with the twofold aim of summarizing the existing results and pointing out possible directions for future research.
Mutual authentication in self-organized VANETs
Creators: name: Caballero-Gil, Cándido
name: Caballero-Gil, Pino
name: Molina-Gil, Jezabel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: The practical deployment of vehicular networks is still a pending issue. In this paper we describe a new self-organized method of authentication for VANETs, which allows their widespread, fast and secure implementation. Our proposal does not involve any central certification authority because the nodes themselves certify the validity of public keys of the other nodes. On the one hand we propose an algorithm that each node must use to choose the public key certificates for its local store. On the other hand, we also describe a new node authentication method based on a cryptographic protocol including a zero-knowledge proof that each node must use to convince another node on the possession of certain secret without revealing anything about it, which allows non-encrypted communication during authentication. Thanks to the combination of the aforementioned tools, the cooperation among vehicles can be used for developing several practical applications of VANETs, such as detection and warning about abnormal traffic conditions. One of the most interesting aspects of our proposal is that it only requires existing devices such as smartphones, because the designed schemes are fully distributed and self-organized. In this work we include an analysis of both an NS-2 simulation and a real device implementation of the proposed algorithms, which enables us to extract promising conclusions and several possible improvements and open questions for further research.
Collective modes of trapped spinor Bose condensates
Creators: name: Trallero-Giner, C.
name: Santiago-Pérez, Darío G.
name: Romero-Rochin, V.
name: Marques, G. E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the richer structures of quasi-one-dimensional Bogoliubov-de Genes collective excitations of F = 1 spinor Bose-Einstein condensate in a harmonic trap potential loaded in an optical lattice. Employing a perturbative method we report general analytical expressions for the confined collective polar and ferromagnetic Goldstone modes. In both cases the excited eigenfrequencies are given as function of the 1D effective coupling constants, trap frequency and optical lattice parameters. It is shown that the main contribution of the optical lattice laser intensity is to shift the confined phonon frequencies. Moreover, for high intensities, the excitation spectrum becomes independent of the self-interaction parameters. We reveal some features of the evolution for the Goldstone modes as well as the condensate densities from the ferromagnetic to the polar phases.