cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Secure Consensus Generation with Distributed DoH
Creators: name: Jeitner, Philipp
name: Shulman, Haya
name: Waidner, Michael
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cryptography and Security (cs.CR)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: Many applications and protocols depend on the ability to generate a pool of servers to conduct majority-based consensus mechanisms and often this is done by doing plain DNS queries. A recent off-path attack [1] against NTP and security enhanced NTP with Chronos [2] showed that relying on DNS for generating the pool of NTP servers introduces a weak link. In this work, we propose a secure, backward-compatible address pool generation method using distributed DNS-over-HTTPS (DoH) resolvers which is aimed to prevent such attacks against server pool generation.
Analytic aspects of the shuffle product
Creators: name: Mishna, Marni
name: Zabrocki, Mike
Publisher: name: arXiv
Year: 2008
Subjects: subject: Information Theory (cs.IT)
subject: Combinatorics (math.CO)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: There exist very lucid explanations of the combinatorial origins of rational and algebraic functions, in particular with respect to regular and context free languages. In the search to understand how to extend these natural correspondences, we find that the shuffle product models many key aspects of D-finite generating functions, a class which contains algebraic. We consider several different takes on the shuffle product, shuffle closure, and shuffle grammars, and give explicit generating function consequences. In the process, we define a grammar class that models D-finite generating functions.
An evolutionary channel for CO-rich and pulsating He-rich subdwarfs
Creators: name: Bertolami, Marcelo M. Miller
name: Battich, Tiara
name: Córsico, Alejandro H.
name: Althaus, Leandro G.
name: Wachlin, Felipe C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recently a new class of hot subluminous stars strongly enriched in C and O have been discovered (CO-sdOs). These stars show abundances very similar to those observed in PG1159 stars but at lower temperatures. Moreover, it has been recently suggested that C and O enrichment might be the key ingredient driving the pulsations in He-rich hot subdwarf stars (He-sdBVs). Here we argue that these two types of rare stars can be explained by a variant of one of the main channels forming hot subdwarf stars. The scenario involves the formation and merging of a He-core white dwarf and a less massive CO-core white dwarf. We have constructed a simple merger models and computed their subsequent evolution. The merger products are in agreement with the surface parameters and composition of CO-sdOs. In addition, we have performed simulations including the effects of element diffusion and the excitation of pulsations. These simulations show that less massive merger products can form stellar structures that have surface parameters, abundances, and pulsation periods similar to those displayed by He-sdBVs. We conclude that the proposed scenario, or some variant of it, offers a very plausible explanation for the formation of CO-sdOs, pulsating He-sdBs and low-luminosity PG1159 stars.
description: 6 Pages, 4Figures. Companion paper to "Discovery of hot subdwarfs with extremely high carbon and oxygen abundances" by Klaus Werner et alia
k-core (bootstrap) percolation on complex networks: Critical phenomena and nonlocal effects
Creators: name: Goltsev, A. V.
name: Dorogovtsev, S. N.
name: Mendes, J. F. F.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Networking and Internet Architecture (cs.NI)
subject: Mathematical Physics (math-ph)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: We develop the theory of the k-core (bootstrap) percolation on uncorrelated random networks with arbitrary degree distributions. We show that the k-core percolation is an unusual, hybrid phase transition with a jump emergence of the k-core as at a first order phase transition but also with a critical singularity as at a continuous transition. We describe the properties of the k-core, explain the meaning of the order parameter for the k-core percolation, and reveal the origin of the specific critical phenomena. We demonstrate that a so-called ``corona'' of the k-core plays a crucial role (corona is a subset of vertices in the k-core which have exactly k neighbors in the k-core). It turns out that the k-core percolation threshold is at the same time the percolation threshold of finite corona clusters. The mean separation of vertices in corona clusters plays the role of the correlation length and diverges at the critical point. We show that a random removal of even one vertex from the k-core may result in the collapse of a vast region of the k-core around the removed vertex. The mean size of this region diverges at the critical point. We find an exact mapping of the k-core percolation to a model of cooperative relaxation. This model undergoes critical relaxation with a divergent rate at some critical moment.
description: 11 pages, 8 figures
Uncertainties associated with the backward integration of dwarf satellites using simple parametric potentials
Creators: name: D'Souza, Richard
name: Bell, Eric F.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: In order to backward integrate the orbits of Milky Way (MW) dwarf galaxies, much effort has been invested in recent years to constrain their initial phase-space coordinates. Yet equally important are the assumptions on the potential that the dwarf galaxies experience over time, especially given the fact that the MW is currently accreting the Large Magellanic Cloud (LMC). In this work, using a dark matter-only zoom-in simulation, we test whether the use of common parametric forms of the potential is adequate to successfully backward integrate the orbits of the subhaloes from their present-day positions. We parametrise the recovered orbits and compare them with those from the simulations. We find that simple symmetric parametric forms of the potential fail to capture the complexities and the inhomogeneities of the true potential experienced by the subhaloes. More specifically, modelling a recent massive accretion like that of the LMC as a sum of two spherical parametric potentials leads to substantial errors in the recovered parameters of the orbits. These errors rival those caused due to a) a 30\% uncertainty in the virial mass of the MW and b) not modelling the potential of the recently accreted massive satellite. Our work suggests that i) the uncertainties in the parameters of the recovered orbits of some MW dwarfs may be under-estimated and that ii) researchers should characterise the uncertainties inherent to their choice of integration techniques and assumptions of the potential against cosmological zoom-in simulations of the MW, which include a recently-accreted LMC.
description: Accepted for publication in MNRAS
Hydrodynamic self-similar cosmological models
Creators: name: Sanyal, Abhik Kumar
name: Banerjee, Asit
name: Ray, Dipankar
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Hydrodynamic self-similar solutions, as obtained by Chi [J. Math. Phys. 24, 2532 (1983)] have been generalized by introducing new variables in place of the old space and time variables. A systematic procedure of obtaining a complete set of solutions has been suggested. The Newtonian analogs of all homogeneous isotropic Friedmann dust universes with spatial curvature $k = 0, \pm 1$ have been given.
description: 14 pages, 0 figures
Do cavities matter? Hollow microgels resist crystallization
Creators: name: Scotti, Andrea
name: Denton, Alan. R.
name: Brugnoni, Monia
name: Schweins, Ralf
name: Richtering, Walter
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Solutions of microgels have been widely used as model systems to gain insight into atomic condensed matter and complex fluids. We explore the thermodynamic phase behavior of hollow microgels, which are distinguished from conventional colloids by possessing a central cavity. Small-angle neutron and X-ray scattering are used to probe hollow microgels in crowded environments. These measurements reveal an interplay between interpenetration and deswelling, and an unusual absence of crystals. Monte Carlo simulations of hollow microgel solutions confirm that, due to the cavity, they form a supercooled liquid more stable than in the case of microgels with a crosslinked core.
Quantum liquid of repulsively bound pairs of particles in a lattice
Creators: name: Petrosyan, David
name: Schmidt, Bernd
name: Anglin, James R.
name: Fleischhauer, Michael
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Repulsively interacting particles in a periodic potential can form bound composite objects, whose dissociation is suppressed by a band gap. Nearly pure samples of such repulsively bound pairs of cold atoms -- "dimers" -- have recently been prepared by Winkler et al. [Nature 441, 853 (2006)]. We here derive an effective Hamiltonian for a lattice loaded with dimers only and discuss its implications to the many-body dynamics of the system. We find that the dimer-dimer interaction includes strong on-site repulsion and nearest-neighbor attraction which always dominates over the dimer kinetic energy at low temperatures. The dimers then form incompressible, minimal-surface "droplets" of a quantum lattice liquid. For low lattice filling, the effective Hamiltonian can be mapped onto the spin-1/2 XXZ model with fixed total magnetization which exhibits a first-order phase transition from the "droplet" to a "gas" phase. This opens the door to studying first order phase transitions using highly controllable ultracold atoms.
description: Corrected dimer energy & references
Shortest Vertex-Disjoint Two-Face Paths in Planar Graphs
Creators: name: De Verdière, Eric Colin
name: Schrijver, Alexander
Publisher: name: arXiv
Year: 2008
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Combinatorics (math.CO)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Let $G$ be a directed planar graph of complexity $n$, each arc having a nonnegative length. Let $s$ and $t$ be two distinct faces of $G$; let $s_1,...,s_k$ be vertices incident with $s$; let $t_1,...,t_k$ be vertices incident with $t$. We give an algorithm to compute $k$ pairwise vertex-disjoint paths connecting the pairs $(s_i,t_i)$ in $G$, with minimal total length, in $O(kn\log n)$ time.
Search for R-parity violating supersymmetry via the LLE couplings lambda_{121}, lambda_{122} or lambda_{133} in ppbar collisions at sqrt(s)=1.96 TeV
Creators: name: D0 Collaboration
name: Abazov, V. M.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: A search for gaugino pair production with a trilepton signature in the framework of R-parity violating supersymmetry via the couplings lambda_121, lambda_122, or lambda_133 is presented. The data, corresponding to an integrated luminosity of L~360/pb, were collected from April 2002 to August 2004 with the D0 detector at the Fermilab Tevatron Collider, at a center-of-mass energy of sqrt(s)=1.96 TeV. This analysis considers final states with three charged leptons with the flavor combinations eel, mumul, and eetau (l=e or mu). No evidence for supersymmetry is found and limits at the 95% confidence level are set on the gaugino pair production cross section and lower bounds on the masses of the lightest neutralino and chargino are derived in two supersymmetric models.
description: 9 pages, 4 figures (fig2 includes 3 subfigures)
Algebraic approach to parafermionic conformal field theories
Creators: name: Noyvert, Boris
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Mathematical Physics (math-ph)
subject: Representation Theory (math.RT)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Parafermionic conformal field theories are considered on a purely algebraic basis. The generalized Jacobi type identity is presented. Systems of free fermions coupled to each other by nontrivial parafermionic type relations are studied in detail. A new parafermionic conformal algebra is introduced, it describes the sl(2|1)/u(1)^2 coset system.
description: 15 pages; v2: 22 pages, essential modifications, added sections and references; v3: published version, minor modifications, typos fixed
Die Reformierte Kirche der Ungarn in Siebenbürgen unmittelbar nach dem Ersten Weltkrieg
Creators: name: Lukács, Olga
Publisher: name: Ökumenische Rundschau
Year: 2025

description: Ökumenische Rundschau, Bd. 63 Nr. 3 (2014): Ökumenische Rundschau, Band 63, Heft 3
Identifying the origin of the non-monotonic thickness dependence of spin-orbit torques and interfacial Dzyaloshinskii-Moriya interaction in a ferrimagnetic insulator heterostructure
Creators: name: Ding, Shilei
name: Baldrati, Lorenzo
name: Ross, Andrew
name: Ren, Zengyao
name: Wu, Rui
name: Becker, Sven
name: Yang, Jinbo
name: Jakob, Gerhard
name: Brataas, Arne
name: Kläui, Mathias
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Electrical manipulation of magnetism via spin-orbit torques (SOTs) promises efficient spintronic devices. In systems comprising magnetic insulators and heavy metals, SOTs have started to be investigated only recently, especially in systems with interfacial Dzyaloshinskii-Moriya interaction (iDMI). Here, we quantitatively study the SOT efficiency and iDMI in a series of gadolinium gallium garnet (GGG) / thulium iron garnet (TmIG) / platinum (Pt) heterostructures with varying TmIG and Pt thicknesses. We find that the non-monotonic SOT efficiency as a function of the magnetic layer thickness is not consistent with the 1/thickness dependence expected from a simple interfacial SOT mechanism. Moreover, considering the insulating nature of TmIG, our results cannot be explained by the SOT mechanism established for metallic magnets where the transverse charge spin current can inject and dephase in the magnetic layers. Rather we can explain this non-monotonic behavior by a model based on the interfacial spin mixing conductance that is affected by the thickness-dependent exchange splitting energy by determining the phase difference of the reflected spin-up and spin-down electrons at the TmIG / Pt interface. By studying the Pt thickness dependence, we find that the effective DMI for GGG / TmIG / Pt does not depend on the Pt thickness, which indicates that the GGG / TmIG interface is the source of the iDMI in this system. Our work demonstrates that SOT and DMI can originate from two different interfaces, which enables independent optimization of DMI and SOT for advanced chiral spintronics with low damping magnetic insulators.
description: 18 pages, 4 figures
The BFKL Pomeron Calculus in zero transverse dimensions: diffractive processes and survival probability for central diffractive production
Creators: name: Kozlov, M.
name: Levin, E.
name: Khachatryan, V.
name: Miller, J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this paper we discuss the processes of diffractive production in the framework of the BFKL Pomeron calculus in zero transverse dimension. Considering the diffractive production of a bunch of particles with not very large masses, namely, $\ln\Lb M^2/m^2 \Rb \ll \frac{1}{\bas} \ln\Lb \frac{N^2_c}{\bas^2}\Rb$, we found explicit formulae for calculation of the cross sections for the single and double diffractive production as well as for the value of the survival probability for the diffractive central production. These formulae include the influence of the correlations due to so called Pomeron loops on the values of all discussed observables. The comparison with the other approaches on the market is given. The main conclusion of this comparison: the Mueller-Patel-Salam-Iancu approximation gives sufficiently good descriptions and close to the exact result for elastic and diffractive cross section but considerable overshoot the value of the survival probability.
description: 25 pages
Statistical mechanics of thermal fluctuations of nearly spherical membranes: the influence of bending and stretching elasticities
Creators: name: Tonchev, Nicholay S.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Theoretical studies of nearly spherical vesicles and microemulsion droplets, that present typical examples for thermally-excited systems that are subject to constraints, are reviewed. We consider the shape fluctuations of such systems constrained by fixed area $A$ and fixed volume $V$, whose geometry is presented in terms of scalar spherical harmonics. These constraints can be incorporated in the theory in different ways. After an introductory review of the two approaches: with an exactly fixed by delta-function membrane area $A$ [Seifert, Z. Phys. B, 97, 299, (1995)] or approximatively by means of a Lagrange multiplier $σ$ conjugated to $A$ [Milner and Safran, Phys. Rev. A, 36, 4371 (1987)], we discuss the determined role of the stretching effects, that has been announced in the framework of a model containing stretching energy term, expressed via the membrane vesicle tension [Bivas and Tonchev, Phys.Rev.E, 100, 022416 (2019)]. Since the fluctuation spectrum for the used Hamiltonian is not exactly solvable an approximating method based on the Bogoliubov inequalities for the free energy has been developed. The area constraint in the last approach appears as a self-consistent equation for the membrane tension. In the general case this equation is intractable analytically. However, much insight into the physics behind can be obtained either imposing some restrictions on the values of the model parameters, or studying limiting cases, in which the self-consistent equation is solved. Implications for the equivalence of ensembles have been discussed as well.
description: This is a review based on a lecture at the Conference in memory of Vyatcheslav Borisovich Priezzhev held in the Bogoliubov Laboratory of Theoretical Physics (JINR-Dubna, 10 September 2019), 26 pages
Geodesic Fréchet Distance Inside a Simple Polygon
Creators: name: Cook, Atlas F.
name: Wenk, Carola
Publisher: name: arXiv
Year: 2008
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Computational Geometry (cs.CG)
subject: FOS: Computer and information sciences

description: We unveil an alluring alternative to parametric search that applies to both the non-geodesic and geodesic Fréchet optimization problems. This randomized approach is based on a variant of red-blue intersections and is appealing due to its elegance and practical efficiency when compared to parametric search. We present the first algorithm for the geodesic Fréchet distance between two polygonal curves $A$ and $B$ inside a simple bounding polygon $P$. The geodesic Fréchet decision problem is solved almost as fast as its non-geodesic sibling and requires $O(N^{2\log k)$ time and $O(k+N)$ space after $O(k)$ preprocessing, where $N$ is the larger of the complexities of $A$ and $B$ and $k$ is the complexity of $P$. The geodesic Fréchet optimization problem is solved by a randomized approach in $O(k+N^{2\log kN\log N)$ expected time and $O(k+N^{2)$ space. This runtime is only a logarithmic factor larger than the standard non-geodesic Fréchet algorithm (Alt and Godau 1995). Results are also presented for the geodesic Fréchet distance in a polygonal domain with obstacles and the geodesic Hausdorff distance for sets of points or sets of line segments inside a simple polygon $P$.
Dynamics of femtosecond synthesized coronary profile laser beams filamentation in air
Creators: name: Geints, Yu. E.
name: Zemlyanov, A. A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Multiple filamentation in air of high-power ultrashort laser radiation with transverse intensity profile resembling a "corona" composed by incoherent combining of several annularly distributed independent top-hat sub-beams is theoretically studied. Through the numerical solution of time-averaged nonlinear Schrodinger equation, we study the spatio-angular dynamics of synthesized near-infrared "corona-beam" (CB) along the optical path by varying the number and power of the beamlets (corona-spikes). For the first time to our knowledge, the evident advances in the multiple filamentation region manipulating of synthesized CB are demonstrated. Particularly, by adjusting the number and aperture of the constituting sub-beams it makes possible to significantly delay the CB filamentation onset distance and increase the filamentation length in air. In addition, at the post-filamentation stage of femtosecond pulse propagation under certain conditions the synthesized corona-beams exhibit significantly lower angular divergence of its most intense part (post-filamentation light channel) compared to the beams with regular uni-modal intensity profiles (Gaussian, plateau-like) that provides enhancing of laser power delivered to the receiver over the atmospheric links.
description: 24 pages, 9 figures
Letter from J.E. McAllister to the Manager of the Royal Bank in Vernon, March 19, 1912
Creators: name: McAllister, John Edgar
Publisher: name: The University of British Columbia
Year: 2017

description: Letter to the manager of the Royal Bank in Vernon from J.E. McAllister, dated March 19, 1912, regarding the transfer of credit from his Coteau account to the Rainbow Ranche and Bellevue Ranche accounts.
Unique photoluminescence response of MoS2 quantum dots over wide range of As (III) in aqueous media
Creators: name: Ansari, Jamilur R.
name: Naseh, Md. Farhan
name: Singh, Neelam
name: Sarkar, Tapan
name: Datta, Anindya
Publisher: name: arXiv
Year: 2020
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Solvothermal synthesis of MoS2 based quantum dots (QDs) and the performance evaluation of bare QDs for the detection of aqueous As (III) oxidative state at room temperature and neutral pH over an extremely wide range (0.1 ppb to 1000 ppb) is reported here. Concentration-dependent photoluminescence (PL) of the QDs was found to be enhanced up to 50 ppb and then suppressed till 1000 ppb, showing two distinctive slopes for enhancement and suppression. Passivation of trap states or defects of QDs may be the possible reason for enhancement, and the formation of extremely small glassy As2S3 particles on the QD surface may be the possible reason for suppression. The pattern of optical absorption of QDs is featureless but shows an enhanced absorbance in the near UV range below 300 nm, which increases with As (III) concentration up to 50 ppb and then decreases following the PL pattern. The MoS2 QDs were characterized by transmission electron microscopy (TEM), Xray diffraction (XRD), UV-Vis, and PL spectroscopy. The enhancement and suppression results can be fitted excellently with the modified Stern-Volmer equation, and the detection of arsenic is possible using these linear fit equations as calibration curves.
Mapping the Discrete Logarithm
Creators: name: Cloutier, Daniel R.
name: Holden, Joshua
Publisher: name: arXiv
Year: 2006
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11A07 (Primary) 11N45, 94A60, 05C05, 11A07, 11-04, 68R10 (Secondary)

description: The discrete logarithm is a problem that surfaces frequently in the field of cryptography as a result of using the transformation g^a mod n. This paper focuses on a prime modulus, p, for which it is shown that the basic structure of the functional graph is largely dependent on an interaction between g and p-1. In fact, there are precisely as many different functional graph structures as there are divisors of p-1. This paper extracts two of these structures, permutations and binary functional graphs. Estimates exist for the shape of a random permutation, but similar estimates must be created for the binary functional graphs. Experimental data suggests that both the permutations and binary functional graphs correspond well to the theoretical data which provides motivation to extend this to larger divisors of p-1 and study the impact this forced structure has on the many cryptographic algorithms that rely on the discrete logarithm for their security. This is especially applicable to those algorithms that require a "safe" prime (p=2q+1, where q is prime) modulus since all non-trivial functional graphs generated using a safe prime modulus can be analyzed by the framework presented here.
description: 13 pages, 4 tables, AMS-LaTeX
Femtosecond Diffractive Imaging with a Soft-X-ray Free-Electron Laser
Creators: name: Chapman, Henry N.
name: Barty, Anton
name: Bogan, Michael J.
name: Boutet, Sebastien
name: Frank, Matthias
name: Hau-Riege, Stefan P.
name: Marchesini, Stefano
name: Woods, Bruce W.
name: Bajt, Sasa
name: Benner, W. Henry
name: London, Richard A.
name: Plonjes, Elke
name: Kuhlmann, Marion
name: Treusch, Rolf
name: Dusterer, Stefan
name: Tschentscher, Thomas
name: Schneider, Jochen R.
name: Spiller, Eberhard
name: Moller, Thomas
name: Bostedt, Christoph
name: Hoener, Matthias
name: Shapiro, David A.
name: Hodgson, Keith O.
name: van der Spoel, David
name: Burmeister, Florian
name: Bergh, Magnus
name: Caleman, Carl
name: Huldt, Gosta
name: Seibert, M. Marvin
name: Maia, Filipe R. N. C.
name: Lee, Richard W.
name: Szoke, Abraham
name: Timneanu, Nicusor
name: Hajdu, Janos
Publisher: name: arXiv
Year: 2006
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 10^13 W/cm^2 pulse, containing 10^12 photons at 32 nm wavelength, produced a coherent diffraction pattern from a nano-structured non-periodic object, before destroying it at 60,000 K. A novel X-ray camera assured single photon detection sensitivity by filtering out parasitic scattering and plasma radiation. The reconstructed image, obtained directly from the coherent pattern by phase retrieval through oversampling, shows no measurable damage, and extends to diffraction-limited resolution. A three-dimensional data set may be assembled from such images when copies of a reproducible sample are exposed to the beam one by one.
description: revtex, 6 pages, 4 figures
INDEXAR repositórios e revistas | Cultura e Ciência num Diretório
Creators: name: Meireles, Paula
name: Seguro de Carvalho, Paula
name: Lopes, Paulo
name: Mendes Moreira, João
Publisher: name: Zenodo
Year: 2024

description: Apresentação realizada na sessão Pecha Kucha III, da 15ª Conferência Lusófona de Ciência Aberta, na Escola Superior de Enfermagem do Porto (ESEP), de 01 a 04 de outubro de 2024.
A Study of Continuous Vector Representationsfor Theorem Proving
Creators: name: Purgał, Stanisław
name: Parsert, Julian
name: Kaliszyk, Cezary
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Applying machine learning to mathematical terms and formulas requires a suitable representation of formulas that is adequate for AI methods. In this paper, we develop an encoding that allows for logical properties to be preserved and is additionally reversible. This means that the tree shape of a formula including all symbols can be reconstructed from the dense vector representation. We do that by training two decoders: one that extracts the top symbol of the tree and one that extracts embedding vectors of subtrees. The syntactic and semantic logical properties that we aim to reserve include both structural formula properties, applicability of natural deduction steps, and even more complex operations like unifiability. We propose datasets that can be used to train these syntactic and semantic properties. We evaluate the viability of the developed encoding across the proposed datasets as well as for the practical theorem proving problem of premise selection in the Mizar corpus.
Moduli of Stable Parabolic Connections, Riemann-Hilbert Correspondence and Geometry of Painlevé Equation of Type VI, Part II
Creators: name: Inaba, Michi-aki
name: Iwasaki, Katsunori
name: Saito, Masa-Hiko
Publisher: name: arXiv
Year: 2006
Subjects: subject: Algebraic Geometry (math.AG)
subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 34M55, 14D20, 32G34, 34G34, 58F05

description: In this paper, we show that the family of moduli spaces of $\balpha'$-stable $(\bt, \blambda)$-parabolic $ϕ$-connections of rank 2 over $\BP^1$ with 4-regular singular points and the fixed determinant bundle of degree -1 is isomorphic to the family of Okamoto--Painlevé pairs introduced by Okamoto \cite{O1} and \cite{STT02}. We also discuss about the generalization of our theory to the case where the rank of the connections and genus of the base curve are arbitrary. Defining isomonodromic flows on the family of moduli space of stable parabolic connections via the Riemann-Hilbert correspondences, we will show that a property of the Riemann-Hilbert correspondences implies the Painlevé property of isomonodromic flows.
description: 29 pages, 1 figures, Adv. Stud. Pure Math., 45, 2006, Proceedings of Moduli spaces and Arithmetic Geometry (Kyoto, 2004)
Hard X-ray luminosity functions of cataclysmic variables: Joint Swift/BAT and Gaia data
Creators: name: Suleimanov, Valery F.
name: Doroshenko, Victor
name: Werner, Klaus
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Cataclysmic variables (CVs) are the most numerous population among the Galactic objects emitting in hard X-rays. Most probably, they are responsible for the extended hard X-ray emission of the Galactic ridge and the central Galactic regions. Here we consider the sample of CVs detected in the all-sky hard X-ray Swift/BAT survey which were also detected by Gaia and thus have reliable distance estimates. Using these data, we derive accurate estimates for local number density per solar mass (ρ_M = 1.37^{+0.3}_{-0.16} x 10^{-5} M_sun^{-1}) and luminosity density per solar mass (ρ_L = 8.95^{+0.15}_{-0.1} x 10^{26} erg s^{-1} M_sun^{-1}) for objects in the sample. These values appear to be in good agreement with the integrated Galactic ridge X-ray emission and Nuclear Stellar Cluster luminosities. Analysis of the differential luminosity functions dρ_M/d(\log_{10} L_x) and dρ_L/d(\log_{10} L_x) confirms that there are two populations of hard X-ray emitting CVs. Intermediate polars dominate at luminosities L > 10^{33} erg s^{-1}, whereas non-magnetic CVs and polars are much more numerous but have lower luminosities on average. As a consequence, the contribution of these populations to the observed hard X-ray luminosity is almost equivalent.
description: 10 pages, 4 figures, 4 tables. Accepted for publication in MNRAS
On Dynamic Breadth-First Search in External-Memory
Creators: name: Meyer, Ulrich
Publisher: name: arXiv
Year: 2008
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences

description: We provide the first non-trivial result on dynamic breadth-first search (BFS) in external-memory: For general sparse undirected graphs of initially $n$ nodes and O(n) edges and monotone update sequences of either $Θ(n)$ edge insertions or $Θ(n)$ edge deletions, we prove an amortized high-probability bound of $O(n/B^{2/3}+\sort(n)\cdot \log B)$ I/Os per update. In contrast, the currently best approach for static BFS on sparse undirected graphs requires $Ω(n/B^{1/2}+\sort(n))$ I/Os.
Cosmic Kite: Auto-encoding the Cosmic Microwave Background
Creators: name: Rios, Martín Emilio de los
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: In this work we present the results of the study of the cosmic microwave background TT power spectrum through auto-encoders in which the latent variables are the cosmological parameters. This method was trained and calibrated using a data-set composed by 80000 power spectra from random cosmologies computed numerically with the CAMB code. Due to the specific architecture of the auto-encoder, the encoder part is a model that estimates the maximum-likelihood parameters from a given power spectrum. On the other hand, the decoder part is a model that computes the power spectrum from the cosmological parameters and can be used as a forward model in a fully Bayesian analysis. We show that the encoder is able to estimate the true cosmological parameters with a precision varying from $\approx 0.004\% $ to $\approx 0.2\% $ (depending on the cosmological parameter), while the decoder computes the power spectra with a mean percentage error of $\approx 0.0018\% $ for all the multipole range. We also demonstrate that the decoder recovers the expected trends when varying the cosmological parameters one by one, and that it does not introduce any significant bias on the estimation of cosmological parameters through a Bayesian analysis. These studies gave place to the Cosmic Kite python software that is publicly available and can be downloaded and installed from https://github.com/Martindelosrios/cosmic-kite. Although this algorithm does not improve the precision of the measurements compared with the traditional methods, it reduces significantly the computation time and represents the first attempt towards forcing the latent variables to have a physical interpretation.
description: Accepted for its publication in MNRAS
A FORTRAN code for $γγ\to Z Z $ in SM and MSSM
Creators: name: Diakonidis, Th.
name: Gounaris, G. J.
name: Layssac, J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Through the present paper, the code gamgamZZ is presented, which may be used to calculate all possible observables related to the process $γγ\to ZZ$, in either the Standard Model (SM), or the minimal sypersymmetric standard model (MSSM) with real parameters.
description: 13 pages, 7 figures Revised according to the EPJC Referee suggestions
Ex vivo estimation of cementless femoral stem stability using an instrumented hammer
Creators: name: Lomami, Hugues Albini
name: Damour, Camille
name: Rosi, Giuseppe
name: Poudrel, Anne-Sophie
name: Dubory, Arnaud
name: Flouzat-Lachaniette, Charles-Henri
name: Haiat, Guillaume
Publisher: name: arXiv
Year: 2020
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: Background 15 The success of cementless hip arthroplasty depends on the primary stability of the femoral stem. It remains difficult to assess the optimal number of impacts to guarantee the femoral stem stability while avoiding bone fracture. The aim of this study is to validate a method using a hammer instrumented with a force sensor to monitor the insertion of femoral stem in bovine femoral samples. Methods 20 Different cementless femoral stem were impacted into five bovine femur samples, leading to 99 configurations. Three methods were used to quantify the insertion endpoint: the impact hammer, video motion tracking and the surgeon proprioception. For each configuration, the number of impacts performed by the surgeon until he felt a correct insertion was noted Nsurg. The insertion depth E was measured through video motion tracking, and the impact number Nvid corresponding to the end of the insertion was estimated. Two indicators, noted I and D, 25 were determined from the analysis of the time variation of the force, and the impact number Nd corresponding to a threshold reached in D variation was estimated. Findings The pullout force of the femoral stem was significantly correlated with I (R${}^2$=0.81). The values of Nsurg, Nvid and Nd were similar for all configurations. 30 Interpretation The results validate the use of the impact hammer to assess the primary stability of the femoral stem and the moment when the surgeon should stop the impaction procedure for an optimal insertion, which could lead to the development of a decision support system. Abstract: 248 words. Main text: 4658 words
Quasiprobability distribution functions for periodic phase-spaces: I. Theoretical Aspects
Creators: name: Ruzzi, M.
name: Marchiolli, M. A.
name: Silva, E. C.
name: Galetti, D.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: An approach featuring $s$-parametrized quasiprobability distribution functions is developed for situations where a circular topology is observed. For such an approach, a suitable set of angle-angular momentum coherent states must be constructed in appropriate fashion.
description: 13 pages, 3 figures
The universal sl(2) cohomology via webs and foams
Creators: name: Caprau, Carmen
Publisher: name: arXiv
Year: 2008
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57M27, 57M25

description: We construct the universal sl(2)-tangle cohomology using an approach with webs and dotted foams. This theory depends on two parameters, and for the case of links it is a categorification of the unnormalized Jones polynomial of the link.
description: 27 pages, many figures; v2: changes following referee's suggestions, typos corrected
Interpretable Machine Learning -- A Brief History, State-of-the-Art and Challenges
Creators: name: Molnar, Christoph
name: Casalicchio, Giuseppe
name: Bischl, Bernd
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: We present a brief history of the field of interpretable machine learning (IML), give an overview of state-of-the-art interpretation methods, and discuss challenges. Research in IML has boomed in recent years. As young as the field is, it has over 200 years old roots in regression modeling and rule-based machine learning, starting in the 1960s. Recently, many new IML methods have been proposed, many of them model-agnostic, but also interpretation techniques specific to deep learning and tree-based ensembles. IML methods either directly analyze model components, study sensitivity to input perturbations, or analyze local or global surrogate approximations of the ML model. The field approaches a state of readiness and stability, with many methods not only proposed in research, but also implemented in open-source software. But many important challenges remain for IML, such as dealing with dependent features, causal interpretation, and uncertainty estimation, which need to be resolved for its successful application to scientific problems. A further challenge is a missing rigorous definition of interpretability, which is accepted by the community. To address the challenges and advance the field, we urge to recall our roots of interpretable, data-driven modeling in statistics and (rule-based) ML, but also to consider other areas such as sensitivity analysis, causal inference, and the social sciences.
The diving physiology of pinnipeds : an evolutionary enquiry
Creators: name: Mottishaw, Petra Deigh
Publisher: name: University of British Columbia
Year: 2009

description: During the last century, studies of diving physiology and biochemistry made great progress in mechanistically explaining the basic diving response of aquatic mammals and birds. Key components of the diving response (apnea, bradycardia, peripheral vasoconstriction, redistribution of cardiac output) were generally taken to be biological adaptations, but the evolution of the diving response has not been seriously examined. This study compares several key characters of the diving response in the pinnipeds using phylogenetically independent contrasts. As the traits examined are known to be functionally important for diving, I expected them to correlate positively with diving ability. Instead, some physiological/biochemical characters considered adaptive for diving do not correlate with diving ability. These traits are similar in phocids (true seals) and otariids (sea lions and fur seals) and include diving apnea and bradycardia (and probably also include tissue hypoperfusion, and hypometabolism of hypoperfused tissues). This finding contradicts the generally accepted theory that these traits are adaptations for extending dive time in pinnipeds. The key components of the diving response are more appropriately seen to be ancestral (plesiomorphic) characters. Another group of physiological/biochemical characters was more variable among the taxa examined. These included body weight, spleen weight, whole body hemoglobin content, and blood volume. Increases in these characters correlate with increased diving capacity (defined as maximum recorded diving duration). This correlation of characters, along with functional knowledge of current utility, leads to the conclusion that changes in two traits - spleen size and whole body oxygen carrying capacities - may have been driven by selection for increased diving duration in pinnipeds.
Martin boundary of a reflected random walk on a half-space
Creators: name: Ignatiouk-Robert, Irina
Publisher: name: arXiv
Year: 2006
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: The complete representation of the Martin compactification for reflected random walks on a half-space $\Z^d\times\N$ is obtained. It is shown that the full Martin compactification is in general not homeomorphic to the ``radial'' compactification obtained by Ney and Spitzer for the homogeneous random walks in $\Z^d$ : convergence of a sequence of points $z_n\in\Z^{d-1}\times\N$ to a point of on the Martin boundary does not imply convergence of the sequence $z_n/|z_n|$ on the unit sphere $S^d$. Our approach relies on the large deviation properties of the scaled processes and uses Pascal's method combined with the ratio limit theorem. The existence of non-radial limits is related to non-linear optimal large deviation trajectories.
description: 42 pages, preprint, CNRS UMR 8088
The Impact of DNS Insecurity on Time
Creators: name: Jeitner, Philipp
name: Shulman, Haya
name: Waidner, Michael
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cryptography and Security (cs.CR)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: We demonstrate the first practical off-path time shifting attacks against NTP as well as against Man-in-the-Middle (MitM) secure Chronos-enhanced NTP. Our attacks exploit the insecurity of DNS allowing us to redirect the NTP clients to attacker controlled servers. We perform large scale measurements of the attack surface in NTP clients and demonstrate the threats to NTP due to vulnerable DNS.
Topological nature of higher-order hinge states revealed by spin transport
Creators: name: Wang, An-Qi
name: Xiang, Peng-Zhan
name: Zhao, Tong-Yang
name: Liao, Zhi-Min
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: One-dimensional (1D) gapless hinge states are predicated in the three-dimensional (3D) higher-order topological insulators and topological semimetals, because of the higher-order bulk-boundary correspondence. Nevertheless, the topologically protected property of the hinge states is still not demonstrated so far, because it is not accessible by conventional methods, such as spectroscopy experiments and quantum oscillations. Here, we reveal the topological nature of hinge states in the higher-order topological semimetal Cd3As2 nanoplate through spin potentiometric measurements. The results of current induced spin polarization indicate that the spin-momentum locking of the higher-order hinge state is similar to that of the quantum spin Hall state, showing the helical characteristics. The spin-polarized hinge states are robust up to room temperature and can nonlocally diffuse a long distance larger than 5 μm, further indicating their immunity protected by topology. Our work deepens the understanding of transport properties of the higher-order topological materials and should be valuable for future electronic and spintronic applications.
Heat release in accreting neutron stars
Creators: name: Gusakov, Mikhail E.
name: Chugunov, Andrey I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Observed thermal emission from accreting neutron stars (NSs) in a quiescent state is believed to be powered by nonequilibrium nuclear reactions that heat the stellar crust (deep crustal heating paradigm). We derive a simple universal formula for the heating efficiency, assuming that an NS has a fully accreted crust. We further show that, within the recently proposed thermodynamically consistent approach to the accreted crust, the heat release can be parametrized by the only one parameter -- the pressure $P_{\rm oi}$ at the outer-inner crust interface (as we argue, this pressure should not necessarily coincide with the neutron-drip pressure). We discuss possible values of $P_{\rm oi}$ for a selection of nuclear models that account for shell effects, and determine the net heat release and its distribution in the crust as a function of $P_{\rm oi}$. We conclude that the heat release should be reduced by a factor of few in comparison to previous works.
description: 5 pages, 1 figure, 1 table + 5 pages supplemental material
Discrete solitons and nonlinear surface modes in semi-infinite waveguide arrays
Creators: name: Molina, M. I.
name: Vicencio, R. A.
name: Kivshar, Y. S.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We discuss the formation of self-trapped localized states near the edge of a semi-infinite array of nonlinear waveguides. We study a crossover from nonlinear surface states to discrete solitons by analyzing the families of odd and even modes centered at different distances from the surface, and reveal the physical mechanism of the nonlinearity-induced stabilization of surface modes.
description: 4 double-column pages, 5 figures, submitted to Optics Letters