cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Quantum amplification of spin currents in cavity magnonics by a parametric drive induced long-lived mode
Creators: name: Mukhopadhyay, Debsuvra
name: Nair, Jayakrishnan M. P.
name: Agarwal, G. S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Cavity-mediated magnon-magnon coupling can lead to a transfer of spin-wave excitations between two spatially separated magnetic samples. We enunciate how the application of a two-photon parametric drive to the cavity can lead to stark amplification in this transfer efficiency. The recurrent multiphoton absorption by the cavity opens up an infinite ladder of accessible energy levels, which can induce higher-order transitions within the magnon Fock space. This is reflected in a heightened spin-current response from one of the magnetic samples when the neighboring sample is coherently pumped. The enhancement induced by the parametric drive can be considerably high within the stable dynamical region. Specifically, near the periphery of the stability boundary, the spin current is amplified by several orders of magnitude. Such striking enhancement factors are attributed to the emergence of parametrically induced strong coherences precipitated by a long-lived mode. While contextualized in magnonics, the generality of the principle would allow applications to energy transfer between systems contained in parametric cavities.
Spectral cube extraction for the VLT/SPHERE IFS: Open-source pipeline with full forward modeling and improved sensitivity
Creators: name: Samland, Matthias
name: Brandt, Timothy
name: Milli, Julien
name: Delorme, Philippe
name: Vigan, Arthur
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present a new open-source data-reduction pipeline to reconstruct spectral data cubes from raw SPHERE integral-field spectrograph (IFS) data. The pipeline is written in Python and based on the pipeline that was developed for the CHARIS IFS. It introduces several improvements to SPHERE data analysis that ultimately produce significant improvements in postprocessing sensitivity. We first used new data to measure SPHERE lenslet point spread functions (PSFs) at the four laser calibration wavelengths. These lenslet PSFs enabled us to forward-model SPHERE data, to extract spectra using a least-squares fit, and to remove spectral crosstalk using the measured lenslet PSFs. Our approach also reduces the number of required interpolations, both spectral and spatial, and can preserve the original hexagonal lenslet geometry in the SPHERE IFS. In the case of least-squares extraction, no interpolation of the data is performed. We demonstrate this new pipeline on the directly imaged exoplanet 51 Eri b and on observations of the hot white dwarf companion to HD 2133. The extracted spectrum of HD 2133B matches theoretical models, demonstrating spectrophotometric calibration that is good to a few percent. Postprocessing on two 51 Eri b data sets demonstrates a median improvement in sensitivity of 80% and 30% for the 2015 and 2017 data, respectively, compared to the use of cubes reconstructed by the SPHERE Data Center. The largest improvements are seen for poorer observing conditions. The new SPHERE pipeline takes less than three minutes to produce a data cube on a modern laptop, making it practical to reprocess all SPHERE IFS data.
description: 17 pages, 11 figures. Software available at: https://github.com/PrincetonUniversity/charis-dep
title: Adjoint Navier-Stokes methods for hydrodynamic shape optimisation
title: Adjungierte Navier-Stokes-Methode für hydrodynamische Zielfunktionsableitungen
titleType: AlternativeTitle
Creators: name: Stück, Arthur
Publisher: name: TUHH Universitätsbibliothek
Year: 2012
Subjects: subject: adjungierte Navier-Stokes-Methode
subject: Druckkorrekturverfahren
subject: Finite-Volumen-Methode
subject: inkompressible Strömung
subject: Formoptimierung
subject: Adjoint Navier-Stokes method
subject: sensitivity analysis
subject: pressure-correction method
subject: finite-volume method
subject: incompressible flow
subject: shape optimisation
classificationCode: 50.33
subject: Technische Strömungsmechanik
subject: Navier-Stokes-Gleichung
subject: Finite-Volumen-Methode
subject: inkompressible Strömung
subject: Gestaltoptimierung

description: Zur effizienten Berechnung hydrodynamischer Zielfunktionsableitungen nach der Form wurden die adjungierten Navier-Stokes Gleichungen analytisch hergeleitet. Auf Basis der primalen Finite-Volumen-Diskretisierung wurden konsistente adjungierte Diskretisierungsschemata entwickelt und im Rahmen eines Druckkorrekturalgorithmus für unstrukturierte Gitter implementiert. Das Verfahren wurde gegen analytische Lösungen validiert und numerisch verifiziert. Es wurde eine adjungierte Sensitivitätsanalyse hinsichtlich der Nachstromqualität eines Schiffsrumpfes durchgeführt, um eine manuelle Formmodifikation des Rumpfes zu unterstützen. Außerdem wurden automatisierte Formoptimierungen zur Reduktion der Energiedissipation in Innenströmungen durchgeführt.
description: To efficiently calculate the sensitivity derivative of hydrodynamic objective functionals with respect to the shape, the adjoint Navier-Stokes equations were derived analytically. Consistent adjoint discretisation schemes were developed term-wise from the primal finite-volume discretisation. The adjoint method, implemented in the framework of a general-purpose pressure-correction based RANS code for unstructured grids, was validated against analytical solutions and verified by means of the direct-differentiation method. The adjoint-based sensitivity derivative was computed to guide a manual re-design of a ship hull to improve the wake field. Moreover, automatic shape-optimisation runs were carried out to reduce the power loss for ducted flows.
$\mathcal{PT}$ symmetry-protected exceptional cones and analogue Hawking radiation
Creators: name: Stålhammar, Marcus
name: Larana-Aragon, Jorge
name: Rødland, Lukas
name: Kunst, Flore K.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Non-Hermitian Hamiltonians, which effectively describe dissipative systems, and analogue gravity models, which simulate properties of gravitational objects, comprise seemingly different areas of current research. Here, we investigate the interplay between the two by relating parity-time-symmetric dissipative Weyl-type Hamiltonians to analogue Schwarzschild black holes emitting Hawking radiation. We show that the exceptional points of these Hamiltonians form tilted cones mimicking the behavior of the light cone of a radially infalling observer approaching a black hole horizon. We further investigate the presence of tunneling processes, reminiscent of those happening in black holes, in a concrete example model. We interpret the non-trivial result as the purely thermal contribution to analogue Hawking radiation in a Schwarzschild black hole. Assuming that our particular Hamiltonian models a photonic crystal, we discuss the concrete nature of the analogue Hawking radiation in this particular setup.
description: Accepted in New Journal of Physics 12+3 pages, 2+1 figures
Graded index and randomly oriented core-shell silicon nanowires with broadband and wide angle antireflection for photovoltaic cell applications
Creators: name: Pignalosa, P.
name: Lee, H.
name: Qiao, L.
name: Tseng, M.
name: Yi, Yasha
Publisher: name: arXiv
Year: 2011
Subjects: subject: Optics (physics.optics)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm) and wide angle (from normal incidence to 60\degree) antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si) nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.
PVT v2: Improved Baselines with Pyramid Vision Transformer
Creators: name: Wang, Wenhai
name: Xie, Enze
name: Li, Xiang
name: Fan, Deng-Ping
name: Song, Kaitao
name: Liang, Ding
name: Lu, Tong
name: Luo, Ping
name: Shao, Ling
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Transformer recently has presented encouraging progress in computer vision. In this work, we present new baselines by improving the original Pyramid Vision Transformer (PVT v1) by adding three designs, including (1) linear complexity attention layer, (2) overlapping patch embedding, and (3) convolutional feed-forward network. With these modifications, PVT v2 reduces the computational complexity of PVT v1 to linear and achieves significant improvements on fundamental vision tasks such as classification, detection, and segmentation. Notably, the proposed PVT v2 achieves comparable or better performances than recent works such as Swin Transformer. We hope this work will facilitate state-of-the-art Transformer researches in computer vision. Code is available at https://github.com/whai362/PVT.
description: Accepted to CVMJ 2022
Translation Representations and Scattering By Two Intervals
Creators: name: Jorgensen, Palle
name: Pedersen, Steen
name: Tian, Feng
Publisher: name: arXiv
Year: 2012
Subjects: subject: Spectral Theory (math.SP)
subject: Quantum Physics (quant-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Studying unitary one-parameter groups in Hilbert space (U(t),H), we show that a model for obstacle scattering can be built, up to unitary equivalence, with the use of translation representations for L2-functions in the complement of two finite and disjoint intervals. The model encompasses a family of systems (U (t), H). For each, we obtain a detailed spectral representation, and we compute the scattering operator, and scattering matrix. We illustrate our results in the Lax-Phillips model where (U (t), H) represents an acoustic wave equation in an exterior domain; and in quantum tunneling for dynamics of quantum states.
Harvesting Planck radiation for free-space optical communications in the LWIR band
Creators: name: Weinstein, Haley A.
name: Cai, Zhi
name: Cronin, Stephen B.
name: Habif, Jonathan L.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: Signal Processing (eess.SP)
subject: Optics (physics.optics)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: We demonstrate a free-space optical communication link with an optical transmitter that harvests naturally occurring Planck radiation from a warm body and modulates the emitted intensity. The transmitter exploits an electro-thermo-optic effect in a multilayer graphene device that electrically controls the surface emissivity of the device resulting in control of the intensity of the emitted Planck radiation. We design an amplitude-modulated optical communication scheme and provide a link budget for communications data rate and range based on our experimental electro-optic characterization of the transmitter. Finally, we present an experimental demonstration achieving error-free communications at 100 bits per second over laboratory scales.
Atomic level micromagnetic model of recording media switching at elevated temperatures
Creators: name: Mercer, J. I.
name: Plumer, M. L.
name: Whitehead, J. P.
name: van Ek, anf J.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: An atomic level micromagnetic model of granular recording media is developed and applied to examine external field-induced grain switching at elevated temperatures which captures non-uniform reversal modes. The results are compared with traditional methods which employ the Landau-Lifshitz-Gilbert equations based on uniformly magnetized grains with assigned intrinsic temperature profiles for $M(T)$ and $K(T)$. Using nominal parameters corresponding to high-anisotropy FePt-type media envisioned for Energy Assisted Magnetic Recording, our results demonstrate that atomic-level reversal slightly reduces the field required to switch grains at elevated temperatures, but results in larger fluctuations, when compared to a uniformly magnetized grain model.
description: 4 pages, 5 figures
Ultra-tuning of nonlinear drumhead MEMS resonators by electro-thermoelastic buckling
Creators: name: Kanj, Ali
name: Ferrari, Paolo F.
name: van der Zande, Arend M.
name: Vakakis, Alexander F.
name: Tawfick, Sameh
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: Systems and Control (eess.SY)
subject: FOS: Physical sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Nonlinear micro-electro-mechanical systems (MEMS) resonators open new opportunities in sensing and signal manipulation compared to their linear counterparts by enabling frequency tuning and increased bandwidth. Here, we design, fabricate and study drumhead resonators exhibiting strongly nonlinear dynamics and develop a reduced order model (ROM) to capture their response accurately. The resonators undergo electrostatically-mediated thermoelastic buckling which tunes their natural frequency from 4.7 to 11.3 MHz, a factor of 2.4x tunability. Moreover, the imposed buckling switches the nonlinearity of the resonators between purely stiffening, purely softening, and even softening-to-stiffening. Accessing these exotic dynamics requires precise control of the temperature and the DC electrostatic forces near the resonator's critical-buckling point. To explain the observed tunability, we develop a one-dimensional physics-based ROM that predicts the linear and nonlinear response of the fundamental bending mode of these drumhead resonators. The ROM captures the dynamic effects of the internal stresses resulting from three sources: The residual stresses from the fabrication process, the mismatch in thermal expansion between the constituent layers, and lastly, the applied electrostatic forces. The ROM replicates the observed tunability of linear (within 5.5% error) and nonlinear responses even near the states of critical buckling. These remarkable nonlinear and large tunability of the natural frequency are valuable features for on-chip acoustic devices in broad applications such as signal manipulation, filtering, and MEMS waveguides.
Joint Majorization-Minimization for Nonnegative Matrix Factorization with the $β$-divergence
Creators: name: Marmin, Arthur
name: Goulart, José Henrique de Morais
name: Févotte, Cédric
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: This article proposes new multiplicative updates for nonnegative matrix factorization (NMF) with the $β$-divergence objective function. Our new updates are derived from a joint majorization-minimization (MM) scheme, in which an auxiliary function (a tight upper bound of the objective function) is built for the two factors jointly and minimized at each iteration. This is in contrast with the classic approach in which a majorizer is derived for each factor separately. Like that classic approach, our joint MM algorithm also results in multiplicative updates that are simple to implement. They however yield a significant drop of computation time (for equally good solutions), in particular for some $β$-divergences of important applicative interest, such as the squared Euclidean distance and the Kullback-Leibler or Itakura-Saito divergences. We report experimental results using diverse datasets: face images, an audio spectrogram, hyperspectral data and song play counts. Depending on the value of $β$ and on the dataset, our joint MM approach can yield CPU time reductions from about $13\%$ to $78\%$ in comparison to the classic alternating scheme.
What is the market potential for on-demand services as a train station access mode?
Creators: name: Geržinič, N.
name: Cats, O.
name: van Oort, N.
name: Hoogendoorn-Lanser, S.
name: Hoogendoorn, S.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: On-demand mobility services (FLEX) are often proposed as a solution for the first/last mile problem. We study the potential of using FLEX to improve train station access by means of a three-step sequential stated preference survey. We compare FLEX with the bicycle, car and public transport for accessing two alternative train stations. We estimate a joint access mode and train station choice model. Estimating a latent class choice model with different nesting structures, we uncover four distinct segments in the population. Two segments (~50%) with a lower Willingness-to-Pay seem to be more likely to take-up FLEX. Ex-urban car drivers seem to be the most likely segment to adopt FLEX, showing great, since members of this segment are currently frequent users of the private car. Our case study also shows that while FLEX competes primarily with public transport when accessing local stations, it competes primarily with car for reaching distant stations.
Modification of triaxial deformation and change of spectrum in $^{25}_{\ Λ}$Mg caused by $Λ$ hyperon
Creators: name: Isaka, Masahiro
name: Homma, Hiroaki
name: Kimura, Masaaki
name: Doté, Akinobu
name: Ohnishi, Akira
Publisher: name: arXiv
Year: 2011
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The positive-parity states of $^{25}_{\ Λ}$Mg with a $Λ$ hyperon in $s$ orbit were studied with the antisymmetrized molecular dynamics for hypernuclei. We discuss two bands of $^{25}_{\ Λ}$Mg corresponding to the $K^π=0^+$ and $2^+$ bands of $^{24}$Mg. It is found that the energy of the $K^π= 2^+ \otimes Λ_s$ band is shifted up by about 200 keV compared to $^{24}$Mg. This is because the $Λ$ hyperon in $s$ orbit reduces the quadrupole deformation of the $K^π= 0^+ \otimes Λ_s$ band, while it does not change the deformation of the $K^π= 2^+ \otimes Λ_s$ band significantly.
description: 19 pages, 3 figures
The NGC7771+NGC7770 Minor Merger: Harassing the Little One?
Creators: name: Alonso-Herrero, Almudena
name: Ortega, F. Fabian Rosales
name: Sanchez, Sebastian F.
name: Kennicutt, Robert C.
name: Pereira-Santaella, Miguel
name: Diaz, Angeles I.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Numerical simulations of minor mergers, typically having mass ratios greater than 3:1, predict little enhancement in the global star formation activity. However, these models also predict that the satellite galaxy is more susceptible to the effects of the interaction than the primary. We use optical integral field spectroscopy and deep optical imaging to study the NGC7771+NGC7770 interacting system (~10:1 stellar mass ratio) to test these predictions. We find that the satellite galaxy NGC7770 is currently experiencing a galaxy-wide starburst with most of the optical light being from young and post-starburst stellar populations(<1Gyr). This galaxy lies off of the local star-forming sequence for composite galaxies with an enhanced integrated specific star formation rate. We also detect in the outskirts of NGC7770 Halpha emitting gas filaments. This gas appears to have been stripped from one of the two galaxies and is being excited by shocks. All these results are consistent with a minor-merger induced episode(s) of star formation in NGC7770 after the first close passage. Such effects are not observed on the primary galaxy NGC7771.
description: Accepted for publication in MNRAS Letters
On the Optimal Configuration of a Square Array Group Testing Algorithm
Creators: name: Čižikovienė, Ugnė
name: Skorniakov, Viktor
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistics Theory (math.ST)
subject: FOS: Mathematics

description: Up to date, only lower and upper bounds for the optimal configuration of a Square Array (A2) Group Testing (GT) algorithm are known. We establish exact analytical formulae and provide a couple of applications of our result. First, we compare the A2 GT scheme to several other classical GT schemes in terms of the gain per specimen attained at optimal configuration. Second, operating under objective Bayesian framework with the loss designed to attain minimum at optimal GT configuration, we suggest the preferred choice of the group size under natural minimal assumptions: the prior information regarding the prevalence suggests that grouping and application of A2 is better than individual testing. The same suggestion is provided for the Minimax strategy.
Riesz transform for a flow Laplacian on homogeneous trees
Creators: name: Levi, Matteo
name: Martini, Alessio
name: Santagati, Federico
name: Tabacco, Anita
name: Vallarino, Maria
Publisher: name: arXiv
Year: 2021
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 05C05, 05C21, 42B20, 43A99

description: We prove the $L^p$-boundedness, for $p \in (1,\infty)$, of the first order Riesz transform associated to the flow Laplacian on a homogeneous tree with the canonical flow measure. This result was previously proved to hold for $p \in (1,2]$ by Hebisch and Steger, but their approach does not extend to $p>2$ as we make clear by proving a negative endpoint result for $p = \infty$ for such operator. We also consider a class of ``horizontal Riesz transforms'' corresponding to differentiation along horocycles, which inherit all the boundedness properties of the Riesz transform associated to the flow Laplacian, but for which we are also able to prove a weak type $(1,1)$ bound for the adjoint operators, in the spirit of the work by Gaudry and Sjögren in the continuous setting. The homogeneous tree with the canonical flow measure is a model case of a measure-metric space which is nondoubling, of exponential growth, does not satisfy the Cheeger isoperimetric inequality, and where the Laplacian does not have spectral gap.
Discovery of the actinium, thorium, protactinium, and uranium isotopes
Creators: name: Fry, C.
name: Thoennessen, M.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Currently, 31 actinium, 31 thorium, 28 protactinium, and 23 uranium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
description: Accepted for publication in Atomic Data Nuclear Data Tables
Design and Construction of Absorption Cells for Precision Radial Velocities in the K Band using Methane Isotopologues
Creators: name: Anglada-Escudé, Guillem
name: Plavchan, Peter
name: Mills, Sean
name: Gao, Peter
name: García-Berríos, Edgardo
name: Lewis, Nathan S.
name: Sung, Keeyoon
name: Ciardi, David R.
name: Beichman, Chas A.
name: Brinkworth, Carolyn
name: Johnson, John A.
name: Davison, Cassy
name: White, Russel J.
name: Prato, Lisa A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We present a method to optimize absorption cells for precise wavelength calibration in the near-infrared. We apply it to design and optimize methane isotopologue cells for precision radial velocity measurements in the K band. We also describe the construction and installation of two such cells for the CSHELL spectrograph at NASA's IRTF. We have obtained their high-resolution laboratory spectra, which we can then use in precision radial velocity measurements and which can also have other applications. In terms of obtainable RV precision methane should out-perform other proposed cells, such as the ammonia cell ($^{14}$NH$_{3}$) recently demonstrated on CRIRES/VLT. The laboratory spectra of Ammonia and the Methane cells show strong absorption features in the H band that could also be exploited for precision Doppler measurements. We present spectra and preliminary radial velocity measurements obtained during our first-light run. These initial results show that a precision down to 20-30 m s$^{-1}$ can be obtained using a wavelength interval of only 5 nm in the K band and S/N$\sim$150. This supports the prediction that a precision down to a few m s$^{-1}$ can be achieved on late M dwarfs using the new generation of NIR spectrographs, thus enabling the detection of terrestrial planets in their habitable zones. Doppler measurements in the NIR can also be used to mitigate the radial velocity jitter due to stellar activity enabling more efficient surveys on young active stars.
description: accepted PASP, Apr 2012 (in press). Preprint version with 36 pages, 9 Figures, 2 Tables
Schwinger-Dyson truncations in the all-soft limit: a case study
Creators: name: Aguilar, A. C.
name: Ferreira, M. N.
name: Oliveira, B. M.
name: Papavassiliou, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We study a special Schwinger-Dyson equation in the context of a pure SU(3) Yang-Mills theory, formulated in the background field method. Specifically, we consider the corresponding equation for the vertex that governs the interaction of two background gluons with a ghost-antighost pair. By virtue of the background gauge invariance, this vertex satisfies a naive Slavnov-Taylor identity, which is not deformed by the ghost sector of the theory. In the all-soft limit, where all momenta vanish, the form of this vertex may be obtained exactly from the corresponding Ward identity. This special result is subsequently reproduced at the level of the Schwinger-Dyson equation, by making extensive use of Taylor's theorem and exploiting a plethora of key relations, particular to the background field method. This information permits the determination of the error associated with two distinct truncation schemes, where the potential advantage from employing lattice data for the ghost dressing function is quantitatively assessed.
description: 29 pages, 9 figures
Analysis of CKM-Favored Quasi-Two-Body $B \to D (R\to) K π$ Decays in PQCD Approach
Creators: name: Zou, Zhi-Tian
name: Fang, Wen-Sheng
name: Liu, Xin
name: Li, Ying
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: LHCb Collaboration studied the resonant structure of $B_s\to \overline{D}^0K^-π^+$ decays using the Dalitz plot analysis technique, based on a data sample corresponding to an integrated luminosity of $3.0{\rm fb}^{-1}$ of $pp$ collision. The $K^-π^+$ components have been analyzed in the amplitude model, where the decay amplitude is modeled to be the resonant contributions with respect to the intermediate resonances $K^*(892)$, $K_0^*(1430)$ and $K_2^*(1430)$. Motivated by the experimental results, we investigate the color-favored quasi-two-body $B \to \overline{D}^0Kπ$ decays in the framework of the perturbative QCD (PQCD) approach. We calculate the the branching fractions by introducing the appropriate wave functions of $Kπ$ pair. Our results are in agreement well the available data, and others can be tested in LHCb and Belle-II experiments. Using the narrow-width-approximation, we also extract the branching fractions of the corresponding two-body $B\to \overline D R$ decays, which agree to the previous theoretical calculations and the experimental data within the errors. There are no $CP$ asymmetries in these decays in the standard model, because these decays are all governed by only the tree operators.
description: 18 pages, 1 figures
Differential-Critic GAN: Generating What You Want by a Cue of Preferences
Creators: name: Yao, Yinghua
name: Pan, Yuangang
name: Tsang, Ivor W.
name: Yao, Xin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: This paper proposes Differential-Critic Generative Adversarial Network (DiCGAN) to learn the distribution of user-desired data when only partial instead of the entire dataset possesses the desired property. DiCGAN generates desired data that meets the user's expectations and can assist in designing biological products with desired properties. Existing approaches select the desired samples first and train regular GANs on the selected samples to derive the user-desired data distribution. However, the selection of the desired data relies on global knowledge and supervision over the entire dataset. DiCGAN introduces a differential critic that learns from pairwise preferences, which are local knowledge and can be defined on a part of training data. The critic is built by defining an additional ranking loss over the Wasserstein GAN's critic. It endows the difference of critic values between each pair of samples with the user preference and guides the generation of the desired data instead of the whole data. For a more efficient solution to ensure data quality, we further reformulate DiCGAN as a constrained optimization problem, based on which we theoretically prove the convergence of our DiCGAN. Extensive experiments on a diverse set of datasets with various applications demonstrate that our DiCGAN achieves state-of-the-art performance in learning the user-desired data distributions, especially in the cases of insufficient desired data and limited supervision.
Representation for alphanumeric data type based on space and speed case study: Student ID of X university
Creators: name: Pratondo, Agus
Publisher: name: arXiv
Year: 2011
Subjects: subject: Databases (cs.DB)
subject: FOS: Computer and information sciences

description: ID is derived from the word identity, derived from the first two characters in the word. ID is used to distinguish between an entity to another entity. Student ID (SID) is the key differentiator between a student with other students. On the concept of database, the differentiator is unique. SID can be numbers, letters, or a combination of both (alphanumeric). Viewed from the daily context, it is not important to determine which a SID belongs to the type of data. However, when reviewed on database design, determining the type of data, including SID in this case, is important. Problems arise because there is a contradiction between the data type viewed from the data characteristic and practical needs. Type of data for SID is a string, if it is evaluated from the basic concepts and its characteristic. It is acceptable because SID consists of a set of numbers which will not be meaningful if applied arithmetic operations like addition, subtraction, multiplication and division. But in terms of computer organization, data representation type will determine how much data space requirements, speed of access, and speed of operation. By considering the constraints of space and speed on the experiments conducted, SID is better expressed as an integer rather than a set of characters. KEYWORDS aphanumeric,representation, string, integer, space, speed
On the geometry of electrovacuum spaces in higher dimensions
Creators: name: Andrade, Maria
name: Leandro, Benedito
name: Lousa, Róbson
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Differential Geometry (math.DG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: A classical question in general relativity is about the classification of regular static black hole solutions of the static Einstein-Maxwell equations (or electrovacuum system). In this paper, we prove some classification results for an electrovacuum system such that the electric potential is a smooth function of the lapse function. In particular, we show that an n-dimensional locally conformally flat extremal electrovacuum space must be in the Majumdar-Papapetrou class. Also, we prove that any three or four dimensional extremal electrovacuum space must be locally conformally flat. Moreover, we prove that an n-dimensional subextremal electrovacuum space with fourth-order divergence free Weyl tensor and zero radial Weyl curvature such that the electric potential is in the Reissner-Nordström class is locally a warped product manifold with (n-1)-dimensional Einstein fibers. Finally, a three dimensional subextremal electrovacuum space with third-order divergence free Cotton tensor was also classified.
CO($J$=1-0) mapping survey of 64 galaxies in the Fornax cluster with the ALMA Morita array
Creators: name: Morokuma-Matsui, Kana
name: Bekki, Kenji
name: Wang, Jing
name: Serra, Paolo
name: Koyama, Yusei
name: Morokuma, Tomoki
name: Egusa, Fumi
name: For, Bi-Qing
name: Nakanishi, Kouichiro
name: Koribalski, Bäbel S.
name: Okamoto, Takashi
name: Kodama, Tadayuki
name: Lee, Bumhyun
name: Maccagni, Filippo M.
name: Miura, Rie E.
name: Espada, Daniel
name: Takeuchi, Tsutomu T.
name: Yang, Dong
name: Lee, Minju M.
name: Ueda, Masaki
name: Matsushita, Kyoko
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We conduct a $^{12}$C$^{16}$O($J$=1-0) (hereafter CO) mapping survey of 64 galaxies in the Fornax cluster using the ALMA Morita array in cycle 5. CO emission is detected from 23 out of the 64 galaxies. Our sample includes dwarf, spiral and elliptical galaxies with stellar masses of $M_{\rm star}\sim10^{6.3-11.6}$~M$_\odot$. The achieved beam size and sensitivity are $15''\times8''$ and $\sim12$~mJy~beam$^{-1}$ at the velocity resolution of $\sim10$~km~s$^{-1}$, respectively. We study the cold-gas (molecular- and atomic-gas) properties of 38 subsamples with $M_{\rm star}>10^9$~M$_\odot$ combined with literature HI data. We find that: (1) the low star-formation (SF) activity in the Fornax galaxies is caused by the decrease in the cold-gas mass fraction with respect to stellar mass (hereafter, gas fraction) rather than the decrease of the SF efficiency from the cold gas; (2) the atomic-gas fraction is more heavily reduced than the molecular-gas fraction of such galaxies with low SF activity. A comparison between the cold-gas properties of the Fornax galaxies and their environmental properties suggests that the atomic gas is stripped tidally and by the ram pressure, which leads to the molecular gas depletion with an aid of the strangulation and consequently SF quenching. Pre-processes in the group environment would also play a role in reducing cold-gas reservoirs in some Fornax galaxies.
description: 53 pages, 41 figures, accepted for publication in ApJS
Prescribing net demand for two-stage electricity generation scheduling
Creators: name: Morales, Juan M.
name: Muñoz, Miguel Á.
name: Pineda, Salvador
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Machine Learning (stat.ML)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: We consider a two-stage generation scheduling problem comprising a forward dispatch and a real-time re-dispatch. The former must be conducted facing an uncertain net demand that includes non-dispatchable electricity consumption and renewable power generation. The latter copes with the plausible deviations with respect to the forward schedule by making use of balancing power during the actual operation of the system. Standard industry practice deals with the uncertain net demand in the forward stage by replacing it with a good estimate of its conditional expectation (usually referred to as a point forecast), so as to minimize the need for balancing power in real time. However, it is well known that the cost structure of a power system is highly asymmetric and dependent on its operating point, with the result that minimizing the amount of power imbalances is not necessarily aligned with minimizing operating costs. In this paper, we propose a bilevel program to construct, from the available historical data, a prescription of the net demand that does account for the power system's cost asymmetry. Furthermore, to accommodate the strong dependence of this cost on the power system's operating point, we use clustering to tailor the proposed prescription to the foreseen net-demand regime. By way of an illustrative example and a more realistic case study based on the European power system, we show that our approach leads to substantial cost savings compared to the customary way of doing.
The correspondence between a scalar field and an effective perfect fluid
Creators: name: Faraoni, Valerio
Publisher: name: arXiv
Year: 2012
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It is widely acknowledged that, for formal purposes, a minimally coupled scalar field is equivalent to an effective perfect fluid with equation of state determined by the scalar potential. This correspondence is not complete because the Lagrangian densities P and -rho, which are equivalent for a perfect fluid, are not equivalent for a minimally coupled scalar field. The exchange between these two Lagrangian densities amounts to exchanging a canonical scalar field with a phantom scalar field.
description: 5 pages, no figures, to appear in Phys. Rev. D
MCP: Self-supervised Pre-training for Personalized Chatbots with Multi-level Contrastive Sampling
Creators: name: Huang, Zhaoheng
name: Dou, Zhicheng
name: Zhu, Yutao
name: Ma, Zhengyi
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computation and Language (cs.CL)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Personalized chatbots focus on endowing the chatbots with a consistent personality to behave like real users and further act as personal assistants. Previous studies have explored generating implicit user profiles from the user's dialogue history for building personalized chatbots. However, these studies only use the response generation loss to train the entire model, thus it is prone to suffer from the problem of data sparsity. Besides, they overemphasize the final generated response's quality while ignoring the correlations and fusions between the user's dialogue history, leading to rough data representations and performance degradation. To tackle these problems, we propose a self-supervised learning framework MCP for capturing better representations from users' dialogue history for personalized chatbots. Specifically, we apply contrastive sampling methods to leverage the supervised signals hidden in user dialog history, and generate the pre-training samples for enhancing the model. We design three pre-training tasks based on three types of contrastive pairs from user dialogue history, namely response pairs, sequence augmentation pairs, and user pairs. We pre-train the utterance encoder and the history encoder towards the contrastive objectives and use these pre-trained encoders for generating user profiles while personalized response generation. Experimental results on two real-world datasets show a significant improvement in our proposed model MCP compared with the existing methods.
The strength of diversity: mathematical proof that collections of variable individuals are robust in the face of challenges
Creators: name: Rowlett, Julie
name: Karlsson, Carl-Joar
name: Nursultanov, Medet
Publisher: name: arXiv
Year: 2021
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Can one demonstrate quantitative effects of diversity within a system comprised of distinct individuals on the performance of the system as a whole? Assuming that individuals can be different, we develop a model to interpolate between individual-level interactions and collective-level ramifications. Rooted in theoretical mathematics, the model is not constrained to any specific context. Potential applications include research, education, sports, politics, ecology, agriculture, algorithms, and finance. Our first main contribution is a game theoretic framework for further analysis of the internal composition of an ensemble of individuals and the repercussions for the ensemble as a whole in competition with others. The second main contribution is the rigorous identification of all equilibrium points and strategies. These equilibria suggest a mechanistic underpinning for biological and physical systems to tend towards increasing complexity and entropy, because diversity imparts strength to a system in competition with others.
SARS-CoV-2: Disease Prevalence, Severity, Associated Risk Factors and Predictors in the Accra Metropolis
Creators: name: Aboagye, Frank Twum
name: Acquah, Maame Ekua
name: Ashong, Yvonne
name: Owusu-Frimpong, Isaac
name: Egyam, Bill Clinton
name: Annison, Lawrence
Publisher: name: Zenodo
Year: 2023
Subjects: SARS-CoV-2
RT-PCR
COVID-19
Allplex
Diagnosis
Viruses
Post-Lockdown
Risk factors

description: Post-lockdown studies on the epidemiological profile of SARS-CoV-2 in Ghana have been limited. More so, adherence to preventive measures has significantly reduced and this presents for the resurgence of the disease as has been observed in several sub-Sahara African countries. This study determined the prevalence and severity of SARS-CoV-2 infection and its associated risk factors and predictors within the Accra Metropolis. This was a prospective cross-sectional study conducted between June and August 2022. Nasopharyngeal samples were collected from 268 consenting participants and were subjected to nucleic acid extraction and followed by real-time polymerase chain reaction for the detection and quantification of SARS-CoV-2 RNA. The prevalence of SARS-CoV-2 detected within the Accra Metropolis was 30.2% (CI95: 24.7 – 35.8). Majority of the SARS-CoV-2 infection was diagnosed in females, participants aged 41 – 50 years, and symptomatic participants. Participants aged 10 years and below and females recorded the highest viral load with the highest number of infections recorded in participants aged 41-50 years. Furthermore, there was a significant inverse relationship between the Ct-values of the E-gene, N-gene, and RdRP gene and their corresponding viral load. Predictors of SARS-CoV-2 infection identified were chills, cough, headache, body weakness, sore throat, and dyspnoea in order of decreasing association with SARS-CoV-2 infection. There was a strong association between symptom status, gender, and age and SARS-CoV-2 infection. The findings of the study denote a high prevalence of SARS-CoV-2 within the Accra Metropolis Persons presenting with symptoms related to SARS-CoV-2 infection are most likely to be diagnosed with COVID-19. Attention should be paid to persons presenting with symptoms to help contain the virus as most preventive measures have currently been relaxed. Education on preventive measures and vaccination should thus be intensified.
description: {"references": ["Owusu, M. et al. (2020) 'Epidemiological profile of SARS-CoV-2 among selected regions in Ghana: A cross-sectional retrospective study', PLOS ONE. Edited by F. Di Gennaro, 15(12), p. e0243711. Available at: https://doi.org/10.1371/journal.pone.0243711.", "Corman, V. et al. (2020) 'Diagnostic detection of 2019-nCoV by real-time RT-PCR', World Health Organization, 17, pp. 1\u201313.", "Yang, X. et al. (2020) 'Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study', The Lancet Respiratory Medicine, 8(5), pp. 475\u2013481. Available at: https://doi.org/10.1016/S2213-2600(20)30079-5."]}
Learning GAN-based Foveated Reconstruction to Recover Perceptually Important Image Features
Creators: name: Surace, Luca
name: Wernikowski, Marek
name: Tursun, Cara
name: Myszkowski, Karol
name: Mantiuk, Radosław
name: Didyk, Piotr
Publisher: name: arXiv
Year: 2021
Subjects: subject: Graphics (cs.GR)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: A foveated image can be entirely reconstructed from a sparse set of samples distributed according to the retinal sensitivity of the human visual system, which rapidly decreases with increasing eccentricity. The use of Generative Adversarial Networks has recently been shown to be a promising solution for such a task, as they can successfully hallucinate missing image information. As in the case of other supervised learning approaches, the definition of the loss function and the training strategy heavily influence the quality of the output. In this work,we consider the problem of efficiently guiding the training of foveated reconstruction techniques such that they are more aware of the capabilities and limitations of the human visual system, and thus can reconstruct visually important image features. Our primary goal is to make the training procedure less sensitive to distortions that humans cannot detect and focus on penalizing perceptually important artifacts. Given the nature of GAN-based solutions, we focus on the sensitivity of human vision to hallucination in case of input samples with different densities. We propose psychophysical experiments, a dataset, and a procedure for training foveated image reconstruction. The proposed strategy renders the generator network flexible by penalizing only perceptually important deviations in the output. As a result, the method emphasized the recovery of perceptually important image features. We evaluated our strategy and compared it with alternative solutions by using a newly trained objective metric, a recent foveated video quality metric, and user experiments. Our evaluations revealed significant improvements in the perceived image reconstruction quality compared with the standard GAN-based training approach.