cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Surface-Enhanced Raman Scattering from Au Nanorods, Nanotriangles, and Nanostars with Tuned Plasmon Resonances
Creators: name: Khlebtsov, Boris N.
name: Burov, Andrey M.
name: Zarkov, Sergey V.
name: Khlebtsov, Nikolai G.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Electromagnetic theory predicts that the optimal value of the localized plasmon resonance (LPR) wavelength for the maximal SERS enhancement factor (EF) is half the sum of the laser and Raman wavelengths. For small Raman shifts, the theoretical EF scales as the fourth power of the local field. However, experimental data often disagree with these theoretical conclusions, leaving the question of choosing the optimal plasmon resonance for the maximal SERS signal unresolved. Here, we present experimental data for gold nanorods (AuNRs), gold nanotriangles (AuNTs), and gold nanostars (AuNSTs). The LPR wavelengths were tuned by chemical etching within 550-1050 nm at constant number concentrations of the particles. The particles were functionalized with Cy7.5 and NBT, and the dependence of the intensity at 940 cm-1 (Cy7.5) and 1343 cm-1 (NBT) on the LPR wavelength was examined for laser wavelengths of 633 nm and 785 nm. The electromagnetic SERS EFs were calculated by averaging the product of the local field intensities at the laser and Raman wavelengths over the particle surface and their random orientations. The calculated SERS plasmonic profiles were redshifted compared to the laser wavelength. For 785-nm excitation, the calculated EFs were five to seven times higher than those for 633-nm excitation. With AuNR@Cy7.5 and AuNT@ Cy7.5, the experimental SERS was 35-fold stronger than it was with NBT-functionalized particles, but with AuNST@Cy7.5 and AuNST@NBT, the SERS responses were similar. With all nanoparticles tested, the SERS plasmonic profiles after 785 nm excitation were slightly blue-shifted, as compared with the laser wavelength, possibly owing to the inner filter effect. After 633-nm excitation, the SERS profiles were redshifted, in agreement with EM theory. In all cases, the plasmonic EF profiles were much broadened compared to the calculated ones and did not follow the four-power law.
description: 40 pages, 8 figures, 56 references. Supporting Information: 37 pages, 26 figures
Supplementary document for Extending Plasmonic Response to the Mid-Wave Infrared with All-Epitaxial Composites - 5617070.pdf
Creators: name: Muhowski, Aaron
name: Simmons, Evan
name: Li, Kun
name: Narimanov, Evgenii
name: Podolskiy, Viktor
name: Wasserman, Dan
Publisher: name: Optica Publishing Group
Year: 2022
Subjects: Uncategorized

description: Calculation method and details
Resonant Flavor Oscillations in Electroweak Baryogenesis
Creators: name: Cirigliano, Vincenzo
name: Lee, Christopher
name: Tulin, Sean
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Electroweak baryogenesis (EWBG) in extensions of the Standard Model will be tested quantitatively in upcoming nuclear and particle physics experiments, but only to the extent that theoretical computations are robust. Currently there exist orders-of-magnitude discrepancies between treatments of charge transport dynamics during EWBG performed by different groups, each relying on different sets of approximations. In this work, we introduce a consistent power counting scheme (in ratios of length scales) for treating systematically the dynamics of EWBG: CP-asymmetric flavor oscillations, collisions, and diffusion. Within the context of a simplified model of EWBG, we derive the relevant Boltzmann equations using non-equilibrium field theory, and solve them exactly without ansatz for the functional form of the density matrices. We demonstrate the existence of a resonant enhancement in charge production when the flavor oscillation length is comparable to the wall thickness. We compare our results with the existing treatment of EWBG by Konstandin, Prokopec, Schmidt, and Seco (KPSS) who previously identified the importance of flavor oscillations in EWBG. We conclude: (i) the power counting of KPSS breaks down in the resonant regime, and (ii) this leads to substantial underestimation of the charge generated in the unbroken phase, and potentially of the final baryon asymmetry.
description: 35 pages, 8 figures
Study of Io's sodium jets with the TRAPPIST telescopes
Creators: name: de Becker, Alexander
name: Head, Linus
name: Bonfond, Bertrand
name: Jehin, Emmanuël
name: Manfroid, Jean
name: Yao, Zhonghua
name: Zhang, Binzheng
name: Grodent, Denis
name: Schneider, Nicholas
name: Benkhaldoun, Zouhair
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Io is the most volcanically active body in the Solar System. This volcanic activity results in the ejection of material into Io's atmosphere, which may then escape from the atmosphere to form various structures in the jovian magnetosphere, including the plasma torus and clouds of neutral particles. The physical processes involved in the escape of particles - for example, how the volcanoes of Io provide material to the plasma torus - are not yet fully understood. In particular, it is not clear to what extent the sodium jet, one of the sodium neutral clouds related to Io, is a proxy of processes that populate the various reservoirs of plasma in Jupiter's magnetosphere. Here, we report on observations carried out over 17 nights in 2014-2015, 30 nights in 2021, and 23 nights in 2022-2023 with the TRAPPIST telescopes, in which particular attention was paid to the sodium jet and the quantification of their physical properties (length, brightness). It was found that these properties can vary greatly from one jet to another and independently of the position of Io in its orbit. No clear link was found between the presence of jets and global brightening of the plasma torus and extended sodium nebula, indicating that jets do not contribute straightforwardly to their population. This work also demonstrates the advantage of regular and long-term monitoring to understanding the variability of the sodium jet and presents a large corpus of jet detections against which work in related fields may compare.
description: Alexander de Becker and Linus Head contributed equally to this work and share first authorship
Lasiurus varius
Creators: name: Málaga, Brian A.
name: Díaz, Darwin R.
name: Arias, Sandra
name: Medina, César E.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Chiroptera
Vespertilionidae
Lasiurus
Lasiurus varius

description: Lasiurus varius (n = 7). Argentina: Neuquén, Las Coloradas (MACN 13617 β, MACN 13621 β, MACN 13626 β), Isla Victoria (CML 2005 β); Río Negro, Bariloche (MVZ 158311 β), Beatriz (BMNH 9.1.1.1 β, BMNH 9.1.1.2 β).
description: Published as part of Málaga, Brian A., Díaz, Darwin R., Arias, Sandra & Medina, César E., 2020, Una especie nueva de Lasiurus (Chiroptera: Vespertilionidae) del suroeste de Perú, pp. 1-14 in Revista Mexicana de Biodiversidad 91 on page 12, DOI: 10.22201/ib.20078706e.2020.91.3096, http://zenodo.org/record/4447341
A Perron iteration for the solution of a quadratic vector equation arising in Markovian Binary Trees
Creators: name: Meini, Beatrice
name: Poloni, Federico
Publisher: name: arXiv
Year: 2010
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65C40, 60J80, 65F30, 15B48, 15A24

description: We propose a novel numerical method for solving a quadratic vector equation arising in Markovian Binary Trees. The numerical method consists in a fixed point iteration, expressed by means of the Perron vectors of a sequence of nonnegative matrices. A theoretical convergence analysis is performed. The proposed method outperforms the existing methods for close-to-critical problems.
Kinematic and energy properties of dynamical regular black holes
Creators: name: Murk, Sebastian
name: Soranidis, Ioannis
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Nonsingular black holes have received much attention in recent years as they provide an opportunity to avoid the singularities inherent to the mathematical black holes predicted by general relativity. Based on the assumption that semiclassical physics remains valid in the vicinity of their horizons, we derive kinematic properties of dynamically evolving spherically symmetric regular black holes. We review the Hawking--Ellis classification of their associated energy-momentum tensors and examine the status of the null energy condition in the vicinity of their horizons as well as their interior. In addition, we analyze the trajectory of a moving observer, find that the horizons can be crossed on an ingoing geodesic, and thus entering and exiting the supposedly trapped spacetime region is possible. We outline the ramifications of this result for the information loss problem and black hole thermodynamics. Throughout the article, we illustrate relevant features based on the dynamical generalization of the regular black hole model proposed in J. High Energy Phys. 09, 118 (2022) and elucidate connections to the only self-consistent dynamical physical black hole solutions in spherical symmetry.
description: 13 pages, 6 figures. Published version. Comments welcome!
Supplementary Material from A genetic glimpse of the Chinese straight-tusked elephants
Creators: name: Lin, Haifeng
name: Hu, Jiaming
name: Baleka, Sina
name: Yuan, Junxia
name: Chen, Xi
name: Xiao, Bo
name: Song, Shiwen
name: Du, Zhicheng
name: Lai, Xulong
name: Hofreiter, Michael
name: Sheng, Guilian
Publisher: name: The Royal Society
Year: 2023

description: Supplementary Material for A genetic glimpse of the Chinese straight-tusked elephants
Predicting Expressibility of Parameterized Quantum Circuits using Graph Neural Network
Creators: name: Aktar, Shamminuj
name: Bärtschi, Andreas
name: Badawy, Abdel-Hameed A.
name: Oyen, Diane
name: Eidenbenz, Stephan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Parameterized Quantum Circuits (PQCs) are essential to quantum machine learning and optimization algorithms. The expressibility of PQCs, which measures their ability to represent a wide range of quantum states, is a critical factor influencing their efficacy in solving quantum problems. However, the existing technique for computing expressibility relies on statistically estimating it through classical simulations, which requires many samples. In this work, we propose a novel method based on Graph Neural Networks (GNNs) for predicting the expressibility of PQCs. By leveraging the graph-based representation of PQCs, our GNN-based model captures intricate relationships between circuit parameters and their resulting expressibility. We train the GNN model on a comprehensive dataset of PQCs annotated with their expressibility values. Experimental evaluation on a four thousand random PQC dataset and IBM Qiskit's hardware efficient ansatz sets demonstrates the superior performance of our approach, achieving a root mean square error (RMSE) of 0.03 and 0.06, respectively.
Feedback control of an interacting Bose-Einstein condensate using phase-contrast imaging
Creators: name: Szigeti, Stuart S.
name: Hush, Michael R.
name: Carvalho, Andre R. R.
name: Hope, Joseph J.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The linewidth of an atom laser is limited by density fluctuations in the Bose-Einstein condensate (BEC) from which the atom laser beam is outcoupled. In this paper we show that a stable spatial mode for an interacting BEC can be generated using a realistic control scheme that includes the effects of the measurement backaction. This model extends the feedback theory, based on a phase-contrast imaging setup, presented in \cite{Szigeti:2009}. In particular, it is applicable to a BEC with large interatomic interactions and solves the problem of inadequacy of the mean-field (coherent state) approximation by utilising a fixed number state approximation. Our numerical analysis shows the control to be more effective for a condensate with a large nonlinearity.
description: 12 pages, 5 figures
Exact Foldy-Wouthuysen transformation for a Dirac equation describing the interaction of spin-1/2 relativistic particles with an external electromagnetic field
Creators: name: Gonçalves, Bruno
name: Júnior, Mário M. Dias
name: Eleotério, Larissa F.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The Thomas-Bargmann-Michel-Telegdi (T-BMT) equation is derived using the Exact Foldy-Wouthuysen transformation. Extra new terms were found, and we discuss their possible physical applications. The main point of this work is to detail the procedure to get the general result. We explicitly present the choice of parametrization we used on the initial Hamiltonian and the motivations to take it. We emphasize that the final equations can depend on this choice, and it is possible to prevent the manipulations of the quadratic Hamiltonian become extremely cumbersome. More importantly, it is done in such a way that the transformed equations allow the direct separation into mass, kinetic, and interaction correction terms to the original T-BMT equation.
A new integrable structure associated to the Camassa-Holm peakons
Creators: name: Avan, J.
name: Frappat, L.
name: Ragoucy, E.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We provide a closed Poisson algebra involving the Ragnisco--Bruschi generalization of peakon dynamics in the Camassa--Holm shallow-water equation. This algebra is generated by three independent matrices. From this presentation, we propose a one-parameter integrable extension of their structure. It leads to a new $N$-body peakon solution to the Camassa--Holm shallow-water equation depending on two parameters.
 We present two explicit constructions of a (non-dynamical) $r$-matrix formulation for this new Poisson algebra. The first one relies on a tensorization of the $N$-dimensional auxiliary space by a 4-dimensional space. We identify a family of Poisson commuting quantities in this framework, including the original ones. This leads us to constructing a second formulation identified as a spectral parameter representation.
description: 13 pages, typos corrected
Numerical Simulations of Chromospheric Microflares
Creators: name: Jiang, R. L.
name: Fang, C.
name: Chen, P. F.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: With gravity, ionization, and radiation being considered, we perform 2.5D compressible resistive MHD simulations of chromospheric magnetic reconnection using the CIP-MOCCT scheme. The temperature distribution of the quiet-Sun atmospheric model VALC and the helium abundance (10%) are adopted. Our 2.5D MHD simulation reproduces qualitatively the temperature enhancement observed in chromospheric microflares. The temperature enhancement $ΔT$ is demonstrated to be sensitive to the background magnetic field, whereas the total evolution time $Δt$ is sensitive to the magnitude of the anomalous resistivity. Moveover, we found a scaling law, which is described as $ΔT/Δt \sim {n_H}^{-1.5} B^{2.1} {η_0}^{0.88}$. Our results also indicate that the velocity of the upward jet is much greater than that of the downward jet and the X-point may move up or down.
description: 31 pages; 9 figures; published in ApJ
Search of X-ray emission from roAp stars: The case of gamma Equulei
Creators: name: Stelzer, B.
name: Hummel, C. A.
name: Schöller, M.
name: Hubrig, S.
name: Cowley, C.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The detection of X-ray emission from Ap stars can be an indicator for the presence of magnetic activity and dynamo action, provided different origins for the emission, such as wind shocks and close late-type companions, can be excluded. Here we report on results for gamma Equu, the only roAp star for which an X-ray detection is reported in ROSAT catalogs. We use high resolution imaging in X-rays with Chandra and in the near-infrared with NACO/VLT that allow us to spatially resolve companions down to ~1" and ~0.06" separations, respectively. The bulk of the X-ray emission is associated with a companion of gamma Equu identified in our NACO image. Assuming coevality with the primary roAp star (~900 Myr), the available photometry for the companion points at a K-type star with ~0.6 M_sun. Its X-ray properties are in agreement with the predictions for its age and mass. An excess of photons with respect to the expected background and contribution from the nearby companion is observed near the optical position of gamma Equu. We estimate an X-ray luminosity of log L_x [erg/s] = 26.6 and log(L_x/L_bol) = -7.9 for this emission. A small offset between the optical and the X-ray image leaves some doubt on its association with the roAp star. The faint X-ray emission that we tentatively ascribe to the roAp star is difficult to explain as a solar-like stellar corona due to its very low L_x/L_bol level and the very long rotation period of gamma Equu. It could be produced in magnetically confined wind shocks implying a mass loss rate of ~10^(-14) M_sun/yr or from an additional unknown late-type companion at separation ~0.4". If confirmed by future deeper X-ray observations this emission could point at the origin for the presence of radioactive elements on some roAp stars.
description: Accepted for publication in Astronomy & Astrophysics (5 pages)
Analysis of full-disc H alpha observations: Carrington maps and filament properties in 1909-2022
Creators: name: Chatzistergos, Theodosios
name: Ermolli, Ilaria
name: Banerjee, Dipankar
name: Barata, Teresa
name: Chouinavas, Ioannis
name: Falco, Mariachiara
name: Gafeira, Ricardo
name: Giorgi, Fabrizio
name: Hanaoka, Yoichiro
name: Krivova, Natalie A.
name: Korokhin, Viktor V.
name: Lourenço, Ana
name: Marchenko, Gennady P.
name: Malherbe, Jean-Marie
name: Peixinho, Nuno
name: Romano, Paolo
name: Sakurai, Takashi
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Full disc observations of the Sun in the H$α$ line provide information about the solar chromosphere and in particular about the filaments, which are dark and elongated features that lie along magnetic field polarity inversion lines. This makes them important for studies of solar magnetism. Since full disc H$α$ observations have been performed at various sites since 1800s, with regular photographic data having started in the beginning of the 20th century, they are an invaluable source of information on past solar magnetism. In this work we aimed at deriving accurate information about filaments from historical and modern full disc H$α$ observations. We have consistently processed observations from 15 H$α$ archives spanning 1909-2022. Our data processing includes photometric calibration of the data stored on photographic plates. We have constructed also Carrington maps from the calibrated H$α$ images. We find that filament areas are affected by the bandwidth of the observation. Thus, cross-calibration of the filament areas derived from different archives is needed. We have produced a composite of filament areas from individual archives by scaling all of them to the Meudon series. Our composite butterfly diagram shows very distinctly the common features of filament evolution, that is the poleward migration as well as a decrease in the mean latitude of filaments as the cycle progresses. We also find that during activity maxima, filaments on average cover about 1% of the solar surface. We see only a weak change in the amplitude of cycles in filament areas, in contrast to sunspot and plage areas. Analysis of H$α$ data for archives with contemporaneous Ca II K observations allowed us to identify and verify archive inconsistencies, which will also have implications for reconstructions of past solar magnetism and irradiance from Ca II K data.
description: 21 pages, 14 figures, accepted for publication in A&A
Constraints on the magnetic field in the inter-cluster bridge A399-A401
Creators: name: Balboni, M.
name: Bonafede, A.
name: Bernardi, G.
name: Wittor, D.
name: Vazza, F.
name: Botteon, A.
name: Carretti, E.
name: Shimwell, T.
name: Vacca, V.
name: van Weeren, R. J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Galaxy cluster mergers are natural consequences of the structure formation in the Universe. Such events involve a large amount of energy ($\sim 10^{63}$ erg) dissipated during the process. Part of this energy can be channelled in particle acceleration and magnetic field amplification, enhancing non-thermal emission of the intra- and inter-cluster environment. Recently, low-frequency observations have detected a bridge of diffuse synchrotron emission connecting two merging galaxy clusters, Abell 399 and Abell 401. Such a result provides clear observational evidence of relativistic particles and magnetic fields in-between clusters. In this work, we have used LOw Frequency ARray (LOFAR) observations at 144 MHz to study for the first time the polarized emission in the A399-A401 bridge region. No polarized emission was detected from the bridge region. Assuming a model where polarization is generated by multiple shocks, depolarization can be due to Faraday dispersion in the foreground medium with respect to the shocks. We constrained its Faraday dispersion to be greater than 0.10 rad m$^{-2}$ at 95% confidence level, which corresponds to an average magnetic field of the bridge region greater than 0.46 nG (or 0.41 nG if we include regions of the Faraday spectrum that are contaminated by Galactic emission). This result is largely consistent with the predictions from numerical simulations for Mpc regions where the gas density is $\sim 300$ times larger than the mean gas density.
description: 12 pages, 13 figures; accepted in A&A
Thermal suppression of surface barrier in ultrasmall superconducting structures
Creators: name: Pogosov, W. V.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: In the recent experiment by Cren \textit{et al.} [Phys. Rev. Lett. \textbf{102}, 127005 (2009)], no hysteresis for vortex penetration and expulsion from the nano-island of Pb was observed. In the present paper, we argue that this effect can be associated with the thermoactivated surmounting of the surface barrier by a vortex. The typical entrance (exit) time is found analytically from the Fokker-Planck equation, written in the form suitable for the extreme vortex confinement. We show that this time is several orders of magnitude smaller than 1 second under the conditions of the experiment considered. Our results thus demonstrate a possibility for the thermal suppression of the surface barrier in nanosized low-$T_{c}$ superconductors. We also briefly discuss other recent experiments on vortices in related structures.
description: 12 pages, 2 figures
Transient and asymmetric dust structures in the TeV-bright nova RS Oph revealed by spectropolarimetry
Creators: name: Nikolov, Y.
name: Luna, G. J. M.
name: Stoyanov, K. A.
name: Borisov, G.
name: Mukai, K.
name: Sokoloski, J. L.
name: Avramova-Boncheva, A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: A long-standing question related to nova eruptions is how these eruptions can lead to the formation of dust despite the ostensibly inhospitable environment for dust within the hot, irradiated ejecta. Novae in systems such as the symbiotic binary RS Oph offers a articularly clear view of some nova shocks and any associated dust production. Here we use spectropolarimetric monitoring of the RS Oph starting two days after its eruption in 2021 Aug. to show that: dust was present in the RS Oph system as early as two days into the 2021 eruption; the spatial distribution of this early dust was asymmetric, with components both aligned with and perpendicular to the orbital plane of the binary; between two and nine days after the start of the eruption, this early dust was gradually destroyed; and dust was again created, aligned roughly with the orbital plane of the binary, more than 80 days after the start of the outburst, most likely as a result of shocks that arose as the ejecta interacted with circumbinary material concentrated in the orbital plane. Modelling of X-rays and very-high energy GeV and TeV emission from RS Oph days to months into the 2021 eruption suggests that collisions between the ejecta and the circumbinary material may have led to shock formation in two regions: the polar - perpendicular to the orbital plane where collimated outflows have been observed after prior eruptions, and a circumbinary torus in the orbital plane. The observations described here indicate that dust formed in approximately the same two regions, supporting the connection between shocks and dust in novae and revealing a very early onset of asymmetry. The spectropolarimetric signatures of RS Oph in the first week into the 2021 outburst indicate: polarized flux across the Hα emission line and position angle orientation relative to the radio axis are similar to the spectropolarimetric signatures of AGNs.
description: 9 pages, 10 figures, 1 table, resubmitted to the Astronomy & Astrophysics after the first reviewer's report
Robust reinsurance contracts with risk constraint
Creators: name: Wang, Ning
Publisher: name: Macquarie University
Year: 2022
Subjects: classificationCode: 399999
subject: Other education not elsewhere classified

description: This thesis investigates a class of optimal reinsurance contract problems in continuous time. We use the principal-agent framework to incorporate the bargaining between the insurer and the reinsurer. To this end, we extend the reinsurer's relative safety loading factor which is usually a pre-specified constant in the traditional expected value principle to be time-varying and to represent the reinsurance premium.
 Since the insurance companies should satisfy the regulators' capital requirements and the computation of capital requirements is based on Value-at-Risk (VaR) under Solvency II regime, we introduce the dynamic version of VaR andimpose a dynamic VaR constraint on the insurer. As for the reinsurer, we assumethat she is ambiguity-averse and aims to maximize the expected utility of herterminal wealth under the worst-case scenario of the alternative measures. The dynamic programming technique is applied to derive the principal's Hamilton-Jacobi-Bellman-Isaacs (HJBI) equation and the agent's Hamilton-Jacobi-Bellman(HJB) equation. Additionally, Karush-Kuhn-Tucker (KKT) conditions are utilized to settle the constrained optimization problem of the agent. Explicit expressions for the optimal retained proportional of the claims, the optimal reinsurance premium and the corresponding value functions of the insurer and the reinsurer are derived.
 Finally, we analyze several numerical examples to illustrate economic intuition. Our results show that the reinsurer's ambiguity aversion and the insurer's risk constraint increase the optimal reinsurance premium, which decreases the optimal reinsurance demand of the insurer.
ROSI (Reference Implementation for Open Scientometric Indicators)
Creators: name: Fraumann, Grischa
name: Lilienthal, Svantje
Publisher: name: Zenodo
Year: 2019
Subjects: scientometrics
open science

description: Presentation about ROSI (Reference Implementation for Open Scientometric Indicators) project at Workshop on Open Scientometric Data Infrastructures, Centre for Science and Technology Studies (CWTS), Leiden University, Leiden, 1 March 2019
Linear and parallel learning of Markov random fields
Creators: name: Dror Mizrahi, Yariv
Publisher: name: University of British Columbia
Year: 2014

description: In this thesis, we introduce a new class of embarrassingly parallel parameter learning algorithms for Markov random fields (MRFs) with untied parameters, which are efficient for a large class of practical models. The algorithms parallelize naturally over cliques and, for graphs of bounded degree, have complexity that is linear in the number of cliques. We refer to these algorithms with the acronym LAP, which stands for Linear And Parallel. Unlike their competitors, the marginal versions of the proposed algorithms are fully parallel and for log-linear models they are also data efficient, requiring only the local sufficient statistics of the data to estimate parameters. LAP algorithms are ideal for parameter learning in big graphs and big data applications. The correctness of the newly proposed algorithms relies heavily on the existence and uniqueness of the normalized potential representation of an MRF. We capitalize on this theoretical result to develop a new theory of correctness and consistency of LAP estimators corresponding to different local graph neighbourhoods. This theory also establishes a general condition on composite likelihood decompositions of MRFs that guarantees the global consistency of distributed estimators, provided the local estimators are consistent. We introduce a conditional variant of LAP that enables us to attack parameter estimation of fully-observed models of arbitrary connectivity, including fully connected Boltzmann distributions. Once again, we show consistency for this distributed estimator, and relate it to distributed pseudo-likelihood estimators. Finally, for linear and non-linear inverse problems with a sparse forward operator, we present a new algorithm, named iLAP, which decomposes the inverse problem into a set of smaller dimensional inverse problems that can be solved independently. This parallel estimation strategy is also memory efficient.
Amplitude and frequency variations in PG~0101+039 from K2 photometry -- A pulsating hot B subdwarf star in an unsynchronized binary system
Creators: name: Ma, Xiao-Yu
name: Zong, Weikai
name: Fu, Jian-Ning
name: Charpinet, Stéphane
name: Wang, Jiaxin
name: Xing, Keyu
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: K2 photometry is suitable for the exploitation of mode variability on short timescales in hot B subdwarf stars, which is important to constrain nonlinear quantities addressed by the stellar theory of high-order perturbation in the future. We analyze the $\sim80$~d high-quality K2 data collected on PG~0101+039 and extract the frequency content of oscillation. We then determine its rotational and orbital properties, as well as characterize the dynamics of amplitude and frequency. The frequencies are extracted from light curves via a standard prewhitening technique. The binary information is obtained from variations both in brightness and radial velocities. Amplitude and frequency modulation of oscillation modes are measured by piece-wise light curves and characterized by EMCMC method. We have extracted 137 independent frequencies in PG~0101+039 and derived period spacing of ~252s and 144s for the dipole and quadruple modes, respectively. We derive a rotation rate of 8.81+-0.06d and ~8.60+-0.16d based on g- and p-mode multiplets, implying a marginally differential rotation with a probability of ~ 60%. We find that the rotation period is much shorter than the orbital period of ~0.57d, indicating that this system is not synchronized. Amplitude and frequency modulation are measurable for 44 frequencies with high enough amplitude, including 12 rotational components. We characterize their modulating patterns and find a clear correlation between amplitude and frequency variation, which is linked to nonlinear resonant couplings. In general, the modulating scale and timescale are on an order of a few dozen of nano hertz and a few tens of days, respectively, whose values are important constraints to future calculations of nonlinear amplitude equations.
description: 16 pages, 9 figures, accepted
Electric Dipole Moments and Polarizability in the Quark-Diquark Model of the Neutron
Creators: name: Srivastava, Y. N.
name: Widom, A.
name: Swain, J.
name: Panella, O.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: For a bound state internal wave function respecting parity symmetry, it can be rigorously argued that the mean electric dipole moment must be strictly zero. Thus, both the neutron, viewed as a bound state of three quarks, and the water molecule, viewed as a bound state of ten electrons two protons and an oxygen nucleus, both have zero mean electric dipole moments. Yet, the water molecule is said to have a nonzero dipole moment strength $d=eΛ$ with $Λ_{H_2O} \approx 0.385\ \dot{A}$. The neutron may also be said to have an electric dipole moment strength with $Λ_{neutron} \approx 0.612\ fm$. The neutron analysis can be made experimentally consistent, if one employs a quark-diquark model of neutron structure.
description: four pages, two figures
Selection of powerful radio galaxies with machine learning
Creators: name: Carvajal, R.
name: Matute, I.
name: Afonso, J.
name: Norris, R. P.
name: Luken, K. J.
name: Sánchez-Sáez, P.
name: Cunha, P. A. C.
name: Humphrey, A.
name: Messias, H.
name: Amarantidis, S.
name: Barbosa, D.
name: Cruz, H. A.
name: Miranda, H.
name: Paulino-Afonso, A.
name: Pappalardo, C.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: We developed and trained a pipeline of three machine learning (ML) models than can predict which sources are more likely to be an AGN and to be detected in specific radio surveys. Also, it can estimate redshift values for predicted radio-detectable AGNs. These models, which combine predictions from tree-based and gradient-boosting algorithms, have been trained with multi-wavelength data from near-infrared-selected sources in the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) Spring field. Training, testing, calibration, and validation were carried out in the HETDEX field. Further validation was performed on near-infrared-selected sources in the Stripe 82 field. In the HETDEX validation subset, our pipeline recovers 96% of the initially labelled AGNs and, from AGNs candidates, we recover 50% of previously detected radio sources. For Stripe 82, these numbers are 94% and 55%. Compared to random selection, these rates are two and four times better for HETDEX, and 1.2 and 12 times better for Stripe 82. The pipeline can also recover the redshift distribution of these sources with $σ_{\mathrm{NMAD}}$ = 0.07 for HETDEX ($σ_{\mathrm{NMAD}}$ = 0.09 for Stripe 82) and an outlier fraction of 19% (25% for Stripe 82), compatible with previous results based on broad-band photometry. Feature importance analysis stresses the relevance of near- and mid-infrared colours to select AGNs and identify their radio and redshift nature. Combining different algorithms in ML models shows an improvement in the prediction power of our pipeline over a random selection of sources. Tree-based ML models (in contrast to deep learning techniques) facilitate the analysis of the impact that features have on the predictions. This prediction can give insight into the potential physical interplay between the properties of radio AGNs (e.g. mass of black hole and accretion rate).
description: Accepted for publication in A&A, 24 pages and 21 figures. Updated to include information on retrieval of data and models, which can be obtained from https://zenodo.org/doi/10.5281/zenodo.10220008
Numerical studies on the link between radioisotopic signatures on Earth and the formation of the Local Bubble. II. Advanced modeling of interstellar 26Al, 53Mn, 60Fe, and 244Pu influxes as traces of past supernovae in the solar neighborhood
Creators: name: Schulreich, Michael Mathias
name: Feige, Jenny
name: Breitschwerdt, Dieter
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Measurements of long-lived radioisotopes provide a means, completely independent of other observational channels, to draw conclusions about near-Earth supernovae (SNe) and thus the origin of the Local Bubble (LB). First and foremost in this context is 60Fe, which has already been detected across the Earth and on the Moon. Using Gaia EDR3, we identified 14 SN explosions, with 13 occurring in UCL/LCC, and one in V1062 Sco, all being subgroups of the Sco-Cen OB association. The timing of these explosions was obtained by us through interpolation of rotating stellar evolution tracks via the initial masses of the already exploded massive stars. We further developed a new Monte Carlo-type approach for deriving the trajectories of the SN progenitors. We then performed 3D hydrodynamic simulations based on these initial conditions to explore the evolution of the LB in an inhomogeneous local interstellar medium and the transport of radioisotopes to Earth. The simulations include the stellar winds from the SN progenitors and additional radioisotopes (26Al, 53Mn, and 244Pu) besides 60Fe. We find that (i) our simulations are consistent with measurements of 60Fe, in particular, a peak 2-3 Myr before present, as well as 26Al, 53Mn, and 244Pu data, (ii) stellar winds contribute to the distribution of radioisotopes and also to the dynamics of the LB, (iii) the solar system (SS) entered the LB about 4.6 Myr ago, and (iv) the measured recent influx of 60Fe can be naturally explained by turbulent radioisotopic transport. Our simulations not only support the recent hypothesis that the LB triggered star formation in the solar vicinity through its expansion, but also suggest that the second, separate 60Fe peak measured at 6-9 Myr ago was generated by the passage of the SS through a neighboring superbubble (SB), possibly the Orion-Eridanus SB, prior to its current residence in the LB.
description: 30 pages, 13 figures, accepted for publication in A&A
The Initial-Boundary Value Problem in General Relativity
Creators: name: Reula, Oscar
name: Sarbach, Olivier
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this article we summarize what is known about the initial-boundary value problem for general relativity and discuss present problems related to it.
description: 11 pages, 2 figures. Contribution to a special volume for Mario Castagnino's seventy fifth birthday
An Effective Clustering Approach to Web Query Log Anonymization
Creators: name: Fard, Amin Milani
name: Wang, Ke
Publisher: name: arXiv
Year: 2010
Subjects: subject: Databases (cs.DB)
subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: Web query log data contain information useful to research; however, release of such data can re-identify the search engine users issuing the queries. These privacy concerns go far beyond removing explicitly identifying information such as name and address, since non-identifying personal data can be combined with publicly available information to pinpoint to an individual. In this work we model web query logs as unstructured transaction data and present a novel transaction anonymization technique based on clustering and generalization techniques to achieve the k-anonymity privacy. We conduct extensive experiments on the AOL query log data. Our results show that this method results in a higher data utility compared to the state of-the-art transaction anonymization methods.
description: 9 pages
Investigating the neural basis of spontaneous thought with fMRI and mindfulness meditation
Creators: name: Ellamil, Melissa Marie
Publisher: name: University of British Columbia
Year: 2014

description: One of the most intriguing yet least understood aspects of the human mind is its tendency to give rise to spontaneous, undirected mental processes – thoughts that occur and proceed without our deliberate effort or control. The present dissertation examined the neural basis of spontaneous thought by integrating first-person reports from individuals with extensive introspective training (i.e., mindfulness meditators) with third-person neural measures from fMRI experience sampling procedures. In Experiment 1, time courses of brain activation during self-caught spontaneous thought events revealed that the medial temporal lobe (MTL) was recruited first, suggesting it may be central to the initial generation of spontaneous thoughts. The medial prefrontal cortex (MPFC) showed recruitment next, suggesting it may be important for the subsequent affective elaboration of spontaneous thoughts. The lateral prefrontal cortex (LPFC) showed recruitment last, suggesting it may contribute to further metacognitive evaluation and monitoring of spontaneous thoughts. In Experiment 2, spontaneous thought elaboration events (i.e., when a second thought followed an initial thought) showed increased MPFC activation and decreased MTL activation. Spontaneous thought elaboration may thus engage affective evaluation processes while suppressing associative generation processes. In Experiment 3, spontaneous thoughts reported during high MTL activity (as determined by real-time fMRI software) were associated with meaning-making content such as remembering, planning, and linking concepts. In contrast, spontaneous thoughts reported during low MTL activity were associated with present-centered content such as body sensations, emotions, awareness, and concentration. The level of MTL activation may thus reflect different qualities, but not necessarily different quantities, of spontaneous thought. First-person, introspective information about the timing, sequence, and content of spontaneous thoughts collected in the present experiments helps to refine current accounts of how brain regions consistently implicated in spontaneous thought specifically contribute to its component processes. The present dissertation reflects a step toward expanding the role of first-person, introspective reports in neuroscience in order to enhance our understanding of the full spectrum of human thought.
Global-in-time solutions for the isothermal Matovich-Pearson equations
Creators: name: Feireisl, Eduard
name: Laurencot, Philippe
name: Mikelic, Andro
Publisher: name: arXiv
Year: 2010
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: In this paper we study the Matovich-Pearson equations describing the process of glass fiber drawing. These equations may be viewed as a 1D-reduction of the incompressible Navier-Stokes equations including free boundary, valid for the drawing of a long and thin glass fiber. We concentrate on the isothermal case without surface tension. Then the Matovich-Pearson equations represent a nonlinearly coupled system of an elliptic equation for the axial velocity and a hyperbolic transport equation for the fluid cross-sectional area. We first prove existence of a local solution, and, after constructing appropriate barrier functions, we deduce that the fluid radius is always strictly positive and that the local solution remains in the same regularity class. To the best of our knowledge, this is the first global existence and uniqueness result for this important system of equations.
Leuctra alabama James 1974
Creators: name: Harrison, Audrey B.
name: Stark, Bill P.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Plecoptera
Leuctridae
Leuctra
Leuctra alabama

description: Leuctra alabama James (Figs. 35-37) Leuctra alabama James, 1974:964. Holotype ♂ (INHS), Hwy. 65, 8.3 mi N Hwy 146 jct, Jackson Co., Alabama Material examined. Alabama: Jackson Co., tributary Larkin Fork, Hwy 65, ~ 8 mi N Hwy 146 jct, 18 May 2009, B. Stark, 1♂ (BPS). Madison Co., Cold Spring, Fearn Street, Huntsville, 25 May 2006, B. Stark, I. Sivec, 21♂, 29♀ (BPS). Comments. The Jackson County site listed above is near the type locality for this species, and the Cold Spring site is in an adjacent county. The similarity of the paraprocts of these specimens to those we determine to be L. rickeri suggests the need to examine the types and additional topotype specimens to determine if both species should be considered valid. Types of these species are on loan to a colleague and unavailable for our study (DeWalt pers. com.).
description: Published as part of Harrison, Audrey B. & Stark, Bill P., 2010, Two New Species Of Stoneflies In The Leuctra Ferruginea Group (Plecoptera: Leuctridae), With Notes On The Leuctra Species Known For Mississippi And Alabama, U. S. A., pp. 16-33 in Illiesia 6 (3) on page 26, DOI: 10.5281/zenodo.4759571
description: {"references": ["James, A. M. 1974. Four new species of stoneflies in North America (Plecoptera). Annals of the Entomological Society of America, 67: 964 - 966."]}
Expansion and ongoing cosmic ray acceleration in HESS J1731-347
Creators: name: Doroshenko, Victor
name: Pühlhofer, Gerd
name: Santangelo, Andrea
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Diffusive shock acceleration in supernova remnants (SNRs) is considered one of the prime mechanisms for Galactic Cosmic Ray (GCR) acceleration. It is still unclear, however, whether SNRs can contribute to GCR spectrum up to the ``knee'' (1\,PeV) band as acceleration to such energies requires an efficient magnetic field amplification process around the shocks. The presence of such a process is challenging to test observationally. Here we report on the detection of fast variability of the X-ray synchrotron emission from the forward shock in the supernova remnant HESS J1731-347, which implies the presence of a strong ($\sim$0.2\,mG) field exceeding background values and thus of effective field amplification. We also report a direct measurement of the high forward shock expansion velocity of 4000-5500\,km/s confirming that the SNR is expanding in a tenuous wind bubble blown by the SNR progenitor, is significantly younger (2.4-9\,kyr) than previously assumed by some authors, and only recently started interaction with the dense material outside the bubble. We finally conclude that there is strong evidence for ongoing hadronic CR acceleration in this SNR.
description: 6 pages 3 figures, accepted in A&A