cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Resolving the Dust-to-Metals Ratio and CO-to-H$_2$ Conversion Factor in the Nearby Universe
Creators: name: Chiang, I-Da
name: Sandstrom, Karin M.
name: Chastenet, Jérémy
name: Herrera, Cinthya N.
name: Koch, Eric W.
name: Kreckel, Kathryn
name: Leroy, Adam K.
name: Pety, Jérôme
name: Schruba, Andreas
name: Utomo, Dyas
name: Williams, Thomas
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We investigate the relationship between the dust-to-metals ratio (D/M) and the local interstellar medium environment at ~2 kpc resolution in five nearby galaxies: IC342, M31, M33, M101, and NGC628. A modified blackbody model with a broken power-law emissivity is used to model the dust emission from 100 to 500 um observed by Herschel. We utilize the metallicity gradient derived from auroral line measurements in HII regions whenever possible. Both archival and new CO rotational line and HI 21 cm maps are adopted to calculate gas surface density, including new wide field CO and HI maps for IC342 from IRAM and the VLA, respectively. We experiment with several prescriptions of CO-to-H$_2$ conversion factor, and compare the resulting D/M-metallicity and D/M-density correlations, both of which are expected to be non-negative from depletion studies. The D/M is sensitive to the choice of the conversion factor. The conversion factor prescriptions based on metallicity only yield too much molecular gas in the center of IC342 to obtain the expected correlations. Among the prescriptions tested, the one that yields the expected correlations depends on both metallicity and surface density. The 1-$σ$ range of the derived D/M spans 0.40-0.58. Compared to chemical evolution models, our measurements suggest that the dust growth time scale is much shorter than the dust destruction time scale. The measured D/M is consistent with D/M in galaxy-integrated studies derived from infrared dust emission. Meanwhile, the measured D/M is systematically higher than the D/M derived from absorption, which likely indicates a systematic offset between the two methods.
description: 22 pages, 8 figures, 4 tables; accepted by ApJ
The impact of gateway distribution on the system capacity of CDMA mobile satellite systems
Creators: name: Liang, Hongyi
Publisher: name: University of British Columbia
Year: 2009

description: Recent research indicates that satellite diversity is a practical means of mitigating the effects of satellite fading for Mobile Satellite Systems (MSS) employing CDMA. However, the underlying assumption of such research is that satellite diversity is available all the time, which is not true in reality. We will investigate the impact of improper gateway distribution on the system capacity of MSS. We investigate the principle of distributing the gateways to ensure single and. double satellite service and present some strategies of searching for the optimal gateway distribution for single and double satellite service. To analyze the impact of gateway distributions on the system capacity of MSS, we classify the general mobile terminal environments into five states. By computing the required power margin of each state to reach the same average Bit-Error Rate (BER) and taking the occurrence probability of each state into account, the capacity of a Mobile Satellite System, expressed as the average number of mobile terminals per satellite over the area ranging from South 80° to North 80°, is analytically derived and thoroughly validated by means of computer simulations. After comparing the system capacity of a MSS with improper gateway distributions to that with the optimal gateway distribution, we show that the capacity of a MSS is decreased considerably due to improper gateway distributions. Moreover, the quantitative results indicate that a MSS in a propagation environment of light shadowing suffers more capacity loss due to improper gateway distribution than a MSS in an environment of heavy shadowing.
Spatial soundfield reproduction in complex environments
Creators: name: Wu, Yan Jennifer
Publisher: name: The Australian National University
Year: 2010
Subjects: subject: QC233.W8 2010
subject: Sound-waves Transmission
subject: Signal processing
subject: Spatial systems

description: Personalized sound environments are becoming increasingly important to the entertainment and audio industries. Using spatial multizone soundfield reproduction, an individual sound environment can be produced to each listener inside an enclosure without physical isolations or the use of headphones. Realization of such a multizone soundfield reproduction system is a conceptually challenging problem in acoustic signal processing, as currently most of the existing techniques concentrate on a single zone. This thesis considers the theory and design of a soundfield reproduction system using arrays of loudspeakers in given complex environments including multizone and reverberant environments. Cylindrical harmonic and spherical harmonic analysis are used to provide mathematical descriptions of spatial soundfields. A continuous loudspeaker concept is first developed to overcome the limitations of existing single-zone soundfield reproduction techniques. Three novel approaches to achieve spatial multizone soundfield reproduction are presented. In the first approach, a generalized framework on 2D (height-invariant) multizone soundfield reproduction using a single loudspeaker array is proposed. The reproduction is based on the derivation of an equivalent global soundfield consisting of a number of individual multizone soundfields. A multizone soundfield reproduction problem is then reduced to the reproduction over the entire region. In the second approach, a spatial region filtering technique is presented to suppress interzone interference in the regions of interests and pass the desired soundfields with no distortion. The third approach involves a design and analysis of a multizone soundfield reproduction system using multiple loudspeaker arrays. The performance of these multizone soundfield reproduction approaches have been verified through numerical simulations. The favorable results indicate that the re-production of multiple independent soundfields in separate zones is possible. In addition, this thesis reveals the fundamental limits on 2D multizone sound field reproduction and shows the extensions of multizone soundfield reproduction in reverberant environment. A car model is also proposed to demonstrate that implementing a simultaneous entertainment system in a car is feasible.
Intermediate-mass Black Holes from High Massive-star Binary Fractions in Young Star Clusters
Creators: name: González, Elena
name: Kremer, Kyle
name: Chatterjee, Sourav
name: Fragione, Giacomo
name: Rodriguez, Carl L.
name: Weatherford, Newlin C.
name: Ye, Claire S.
name: Rasio, Frederic A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Black holes formed in dense star clusters, where dynamical interactions are frequent, may have fundamentally different properties than those formed through isolated stellar evolution. Theoretical models for single star evolution predict a gap in the black hole mass spectrum from roughly $40-120\,M_{\odot}$ caused by (pulsational) pair-instability supernovae. Motivated by the recent LIGO/Virgo event GW190521, we investigate whether black holes with masses within or in excess of this "upper-mass gap" can be formed dynamically in young star clusters through strong interactions of massive stars in binaries. We perform a set of $N$-body simulations using the CMC cluster-dynamics code to study the effects of the high-mass binary fraction on the formation and collision histories of the most massive stars and their remnants. We find that typical young star clusters with low metallicities and high binary fractions in massive stars can form several black holes in the upper-mass gap and often form at least one intermediate-mass black hole. These results provide strong evidence that dynamical interactions in young star clusters naturally lead to the formation of more massive black hole remnants.
description: 10 pages, 2 figures, 1 table. Accepted for publication in ApJ Letters. Comments welcome
A note on dual gravitational charges
Creators: name: Oliveri, Roberto
name: Speziale, Simone
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Dual gravitational charges have been recently computed from the Holst term in tetrad variables using covariant phase space methods. We highlight that they originate from an exact 3-form in the tetrad symplectic potential that has no analogue in metric variables. Hence there exists a choice of the tetrad symplectic potential that sets the dual charges to zero. This observation relies on the ambiguity of the covariant phase space methods. To shed more light on the dual contributions, we use the Kosmann variation to compute (quasi-local) Hamiltonian charges for arbitrary diffeomorphisms. We obtain a formula that illustrates comprehensively why the dual contribution to the Hamiltonian charges: (i) vanishes for exact isometries and asymptotic symmetries at spatial infinity; (ii) persists for asymptotic symmetries at future null infinity, in addition to the usual BMS contribution. Finally, we point out that dual gravitational charges can be equally derived using the Barnich-Brandt prescription based on cohomological methods, and that the same considerations on asymptotic symmetries apply.
description: 18 pages; v2: improved version, refs added, matches version accepted for publication
QRnet: optimal regulator design with LQR-augmented neural networks
Creators: name: Nakamura-Zimmerer, Tenavi
name: Gong, Qi
name: Kang, Wei
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optimization and Control (math.OC)
subject: Machine Learning (cs.LG)
subject: Systems and Control (eess.SY)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: In this paper we propose a new computational method for designing optimal regulators for high-dimensional nonlinear systems. The proposed approach leverages physics-informed machine learning to solve high-dimensional Hamilton-Jacobi-Bellman equations arising in optimal feedback control. Concretely, we augment linear quadratic regulators with neural networks to handle nonlinearities. We train the augmented models on data generated without discretizing the state space, enabling application to high-dimensional problems. We use the proposed method to design a candidate optimal regulator for an unstable Burgers' equation, and through this example, demonstrate improved robustness and accuracy compared to existing neural network formulations.
description: Added IEEE accepted manuscript with copyright notice
DVD: A Diagnostic Dataset for Multi-step Reasoning in Video Grounded Dialogue
Creators: name: Le, Hung
name: Sankar, Chinnadhurai
name: Moon, Seungwhan
name: Beirami, Ahmad
name: Geramifard, Alborz
name: Kottur, Satwik
Publisher: name: arXiv
Year: 2021
Subjects: subject: Artificial Intelligence (cs.AI)
subject: Computation and Language (cs.CL)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: A video-grounded dialogue system is required to understand both dialogue, which contains semantic dependencies from turn to turn, and video, which contains visual cues of spatial and temporal scene variations. Building such dialogue systems is a challenging problem, involving various reasoning types on both visual and language inputs. Existing benchmarks do not have enough annotations to thoroughly analyze dialogue systems and understand their capabilities and limitations in isolation. These benchmarks are also not explicitly designed to minimise biases that models can exploit without actual reasoning. To address these limitations, in this paper, we present DVD, a Diagnostic Dataset for Video-grounded Dialogues. The dataset is designed to contain minimal biases and has detailed annotations for the different types of reasoning over the spatio-temporal space of video. Dialogues are synthesized over multiple question turns, each of which is injected with a set of cross-turn semantic relationships. We use DVD to analyze existing approaches, providing interesting insights into their abilities and limitations. In total, DVD is built from $11k$ CATER synthetic videos and contains $10$ instances of $10$-round dialogues for each video, resulting in more than $100k$ dialogues and $1M$ question-answer pairs. Our code and dataset are publicly available at https://github.com/facebookresearch/DVDialogues.
description: 20 pages, 14 figures, 8 tables
(2 + 1) noncommutative gravity and conical spacetimes
Creators: name: Valtancoli, Paolo
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We solve (2+1) noncommutative gravity coupled to point-like sources. We find continuity with Einstein gravity since we recover the classical gravitational field in the $θ\to 0$ limit or at large distance from the source. It appears a limitation on the mass which is twice than expected. Since the distance is not gauge invariant, the measure of the deficit angle near the source is intrinsically ambiguous, with the gauge group playing the role of statistical ensemble. Einstein determinism can be recovered only at large distance from the source, compared with the scale of the noncommutative parameter $\sqrtθ$.
description: 19 pages, LaTeX, no figures
Likelihood-free inference with neural compression of DES SV weak lensing map statistics
Creators: name: Jeffrey, Niall
name: Alsing, Justin
name: Lanusse, François
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: In many cosmological inference problems, the likelihood (the probability of the observed data as a function of the unknown parameters) is unknown or intractable. This necessitates approximations and assumptions, which can lead to incorrect inference of cosmological parameters, including the nature of dark matter and dark energy, or create artificial model tensions. Likelihood-free inference covers a novel family of methods to rigorously estimate posterior distributions of parameters using forward modelling of mock data. We present likelihood-free cosmological parameter inference using weak lensing maps from the Dark Energy Survey (DES) SV data, using neural data compression of weak lensing map summary statistics. We explore combinations of the power spectra, peak counts, and neural compressed summaries of the lensing mass map using deep convolution neural networks. We demonstrate methods to validate the inference process, for both the data modelling and the probability density estimation steps. Likelihood-free inference provides a robust and scalable alternative for rigorous large-scale cosmological inference with galaxy survey data (for DES, Euclid and LSST). We have made our simulated lensing maps publicly available.
description: Accepted MNRAS, 18 pages, 10 figures, submitted MNRAS
Pushing boundaries—selective cooling crystallization as tool for selectivity compensation and product purification using a recyclable Pd/Xantphos catalyst in the methoxycarbonylation of methyl 10-undecenoate
Creators: name: Vondran, Johanna
name: Moeschke, Rebecca
name: Deysenroth, Tabea
name: Seidensticker, Thomas
Publisher: name: TU Dortmund
Year: 2022
Subjects: subject: 1,2-DTBPMB
subject: Carbonylation
subject: Hydroesterification
subject: Methyl 10-undecenoate
subject: 660

description: The homogeneously catalyzed methoxycarbonylation of methyl 10-undecenoate allows for the synthesis of dimethyl 1,12-dodecandioate as an interesting bio-based drop-in alternative for 1,12-dodecandioic acid as polymer building block. Although the benchmark catalyst system of Pd/1,2-bis((di-tert-butylphosphino)methyl)benzene and methane sulfonic acid is very active and selective, long-term stability over a potential catalyst recycling is limited. In this work, modifications of this catalyst system in terms of protonation of the ligand and its replenishment during recycling are first investigated, proving that the reaction system is tolerant against minor changes. Finally, the commercially available ligand Xantphos, featuring higher stability but comes with a rather low l:b selectivity of 70:30, is applied. However, through the application of cooling crystallization, 58 g product (52% isolated yield) with an overall purity of 94% is obtained from the crude reaction solution without further treatment and a ∑TON of 4000 after ten reaction runs, while catalyst loss into the product is low. Practical Applications: Selective syntheses on the basis of renewable resources are a powerful tool for the production of value products in terms of green chemistry. Thereby, homogeneous transition metal catalysts are beneficial regarding selectivity. However, their separation and recycling are challenging due to their limited stability. The combination of a stable, commercially available catalyst with a selective purification method allows for isolation and purification from a crude reaction mixture without the need for any auxiliary or further purification steps. In this work, cooling crystallization is applied for subsequent purification of the linear diester dimethyl 1,12-dodecandioate. Thereby, a lower selectivity from the methoxycarbonylation reaction using the stable Xantphos ligand is compensated and combined with recycling of the homogeneous catalyst. Thus, the development of an integrated process covering a stable catalyst system in the reaction, and high selectivity in the purification is the key toward an efficient homogeneous catalyst recycling.
description: European journal of lipid science and technology;125(5)
Quantum Computing with Spin Qubits Interacting Through Delocalized Excitons: Overcoming Hole Mixing
Creators: name: Lovett, Brendon W.
name: Nazir, Ahsan
name: Pazy, Ehoud
name: Barrett, Sean D.
name: Spiller, Tim P.
name: Briggs, G. Andrew D.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: As a candidate scheme for controllably coupled qubits, we consider two quantum dots, each doped with a single electron. The spin of the electron defines our qubit basis and trion states can be created by using polarized light; we show that the form of the excited trion depends on the state of the qubit. By using the Luttinger-Kohn Hamiltonian we calculate the form of these trion states in the presence of light-heavy hole mixing, and show that they can interact through both the Förster transfer and static dipole-dipole interactions. Finally, we demonstrate that by using chirped laser pulses, it is possible to perform a two-qubit gate in this system by adiabatically following the eigenstates as a function of laser detuning. These gates are robust in that they operate with any realistic degree of hole mixing, and for either type of trion-trion coupling.
description: Updated with published version, references updated
Digital gravity? Firm birth and relocation patterns of young digital firms in Germany
Creators: name: Hellwig, Vanessa
Publisher: name: TU Dortmund
Year: 2022
Subjects: subject: Digital
subject: Firm relocation
subject: Gravity model
subject: ICT
subject: Location choices
subject: Mobility
subject: Start-ups
subject: 330

description: This paper analyses the spatial patterns of young (<10 years) digital firms in Germany between 2008 and 2017 on county level. Determinants of firm birth locations as well as relocations are considered jointly to understand differences in location choices within firms' life cycles. I match commercial register data of 107,321 firms with county-level administrative data to capture local characteristics. Using an OLS model with fixed effects, I find that the local knowledge base—that is, universities, research institutes, and colocated incumbents—are significant key determinants of digital firm birth when controlling for a host of local characteristics. My results indicate that for five firms per 1000 inhabitants, there is around one firm birth. Second, using a fixed effects gravity model for the analysis of relocations, I find that the most dominant explanatory factor for firm relocation across specifications is distance, that is, relocation costs. Relocation flows are more than twice as high to neighboring counties relative to other locations which shows that digital firms are not as footloose as their business model may suggest. Jointly, my results reflect economic activity's regional persistence, particularly for new firms. My paper provides evidence for policies targeting homogenous digital clusters based on strong colocation and that digital economic activity is not shifted over long distances, but the regional entrepreneurship capital is crucial for local growth.
description: Journal of regional science;63(2)
Improved near optimal angular quadratures for polarised radiative transfer in 3D MHD models
Creators: name: Bestard, Jaume Jaume
name: Štěpán, Jiří
name: Bueno, Javier Trujillo
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Accurate angular quadratures are crucial for the numerical solution of three-dimensional (3D) radiative transfer problems, especially when the spectral line polarisation produced by the scattering of anisotropic radiation is included. There are two requirements for obtaining an optimal quadrature and they are difficult to satisfy simultaneously: high accuracy and short computing time. By imposing certain symmetries, we were recently able to derive a set of near optimal angular quadratures. Here, we extend our previous investigation by considering other symmetries. Moreover, we test the performance of our new quadratures by numerically solving a radiative transfer problem of resonance line polarisation in a 3D model of the solar atmosphere resulting from a magneto-hydrodynamical simulation. The new angular quadratures derived here outperform the previous ones in terms of the number of rays needed to achieve any given accuracy.
description: 6 pages, 4 figures; published version in A&A
Analyzing the early structural build-up of accelerated cement pastes
Creators: name: Dorn, Tobias
name: Hirsch, Tamino
name: Stephan, Dietmar
Publisher: name: Technische Universität Berlin
Year: 2021
Subjects: subject: 540 Chemie und zugeordnete Wissenschaften
subject: cement hydration
subject: acceleration
subject: calcium nitrate
subject: Triethanolamine
subject: OPC
subject: in-situ X-ray diffraction

description: Extrusion-based additive manufacturing imposes high requirements on the material stability right after the extrusion. Therefore, a thorough understanding of the chemical reactions that determine the early reduction in processability is necessary. Accelerators are especially considered here, which have a major influence on the early reaction. This study contributes to these issues by analyzing the influence of 0.1 wt% TEA (triethanolamine) and 2.0 wt% Ca(NO3)2 on the hydration of two CEM I 52.5 R. The hydration was analyzed by isothermal heat flow calorimetry and in-situ X-ray diffraction. Vicat needle penetration, a penetrometer of own design, and ultrasonic P-wave velocity development were used to monitor the early change in workability. The obtained results indicate that ettringite formation is the main factor influencing workability during the first 60 min of hydration. Afterwards, the influence of ettringite is exceeded by the formation of C–S–H. Ca(NO3)2 was shown to enhance C–S–H formation and had no significant effect on the workability during the first 60 min of hydration while rapidly decreasing workability during the induction period. TEA was shown to increase brownmillerite dissolution and ettringite formation and, consequently, promote the workability loss during the initial hydration period. The time of initial and final setting determined by the Vicat needle test depended mainly on the formation of C–S–H phases.
The MUSE-Faint survey. II. The dark matter-density profile of the ultra-faint dwarf galaxy Eridanus 2
Creators: name: Zoutendijk, Sebastiaan L.
name: Brinchmann, Jarle
name: Bouché, Nicolas F.
name: Brok, Mark den
name: Krajnović, Davor
name: Kuijken, Konrad
name: Maseda, Michael V.
name: Schaye, Joop
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Aims. We use stellar line-of-sight velocities to constrain the dark matter-density profile of Eridanus 2, an ultra-faint dwarf galaxy ($M_\mathrm{V} = -7.1$, $M_* \approx 9 \times 10^4\,M_\odot$). We furthermore derive constraints on fundamental properties of self-interacting and fuzzy dark matter scenarios. Methods. We present new observations of Eridanus 2 from MUSE-Faint, a survey of ultra-faint dwarf galaxies with MUSE on the Very Large Telescope, and determine line-of-sight velocities for stars inside the half-light radius. Combined with literature data, we have 92 stellar tracers out to twice the half-light radius. We constrain models of cold dark matter, self-interacting dark matter, and fuzzy dark matter with these tracers, using CJAM and pyGravSphere for the dynamical analysis. Results. We find substantial evidence for cold dark matter over self-interacting dark matter and weak evidence for fuzzy dark matter over cold dark matter. We find a virial mass $M_{200} \sim 10^8\,M_\odot$ and astrophysical factors $J(α_\mathrm{c}^J) \sim 10^{11}\,M_\odot^2\,\mathrm{kpc}^{-5}$ and $D(α_\mathrm{c}^D) \sim 10^2$-$10^{2.5}\,M_\odot\,\mathrm{kpc}^{-2}$. We do not resolve a core ($r_\mathrm{c} < 47\,\mathrm{pc}$, 68-% level) or soliton ($r_\mathrm{sol} < 7.2\,\mathrm{pc}$, 68-% level). These limits are equivalent to an effective self-interaction coefficient $fΓ< 2.2 \times 10^{-29}\,\mathrm{cm}^3\,\mathrm{s}^{-1}\,\mathrm{eV}^{-1}\,c^2$ and a fuzzy-dark-matter particle mass $m_\mathrm{a} > 4.0 \times 10^{-20}\,\mathrm{eV}\,c^{-2}$. The constraint on self-interaction is complementary to those from gamma-ray searches. The constraint on fuzzy-dark-matter particle mass is inconsistent with those obtained for larger dwarf galaxies, suggesting that the flattened density profiles of those galaxies are not caused by fuzzy dark matter. (Abridged)
description: 24 pages, 14 figures, 8 tables. Minor changes, electronic table moved to appendix. Version as accepted on 2021-04-24 for publication in A&A
Odd-spin glueballs, AdS/QCD and information entropy
Creators: name: Rodrigues, D. Marinho
name: da Rocha, R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Odd-spin glueballs in the dynamical AdS/QCD model are scrutinized, in the paradigm of the configurational entropy (CE). Configurational-entropic Regge trajectories, that relate the CE underlying odd-spin glueballs to their mass spectra and spin, are then engendered. They predict the mass spectra of odd-spin glueballs, besides pointing towards the configurational stability of odd-spin glueball resonances. The exponential modified dilaton with logarithmic anomalous dimensions comprises the most suitable choice to derive the mass spectra of odd-spin glueballs, compatible to lattice QCD. It is then used in a hybrid paradigm that takes both lattice QCD and the AdS/QCD correspondence into account.
description: 9 pages, 7 figs
Working mechanism of calcium nitrate as an accelerator for Portland cement hydration
Creators: name: Dorn, Tobias
name: Hirsch, Tamino
name: Stephan, Dietmar
Publisher: name: Technische Universität Berlin
Year: 2022
Subjects: subject: 660 Chemische Verfahrenstechnik
subject: acceleration
subject: additives
subject: hydration
subject: Portland cement
subject: thermodynamics

description: Precast concrete, cold weather concreting, and the emerging technique of concrete additive manufacturing are applications in which the acceleration of cement hydration plays a critical role. To allow precise control of early cement hydration in these applications, a thorough understanding of the working mechanisms of cement hydration accelerators is required. This study contributes to the understanding of the mechanism by which calcium nitrate (Ca(NO3)2) influences early cement hydration. The influence of Ca(NO3)2 on the hydration of an ordinary Portland cement has been followed by isothermal calorimetry, in situ X‐ray diffraction (XRD), quantitative XRD, compressive strength testing, and the analysis of the pore solution composition. Further, the initial pore solution, the initial phase composition, and the phase composition in the fully hydrated cement have been estimated by thermodynamic calculations to corroborate the experimentally obtained results. The results indicate that Ca(NO3)2, especially at the highest analyzed dosage of 5 wt.%, enhances the formation of ettringite and a nitrate‐containing AFm phase. Furthermore, Ca(NO3)2 accelerates alite hydration. Besides the increased Ca concentration in solution, it has been found that a reduction of the Al concentration in the initial pore solution by Ca(NO3)2 possibly contributes to the accelerating effect of Ca(NO3)2 on alite hydration.
Depth-Enhanced Feature Pyramid Network for Occlusion-Aware Verification of Buildings from Oblique Images
Creators: name: Zhu, Qing
name: Huang, Shengzhi
name: Hu, Han
name: Li, Haifeng
name: Chen, Min
name: Zhong, Ruofei
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Detecting the changes of buildings in urban environments is essential. Existing methods that use only nadir images suffer from severe problems of ambiguous features and occlusions between buildings and other regions. Furthermore, buildings in urban environments vary significantly in scale, which leads to performance issues when using single-scale features. To solve these issues, this paper proposes a fused feature pyramid network, which utilizes both color and depth data for the 3D verification of existing buildings 2D footprints from oblique images. First, the color data of oblique images are enriched with the depth information rendered from 3D mesh models. Second, multiscale features are fused in the feature pyramid network to convolve both the color and depth data. Finally, multi-view information from both the nadir and oblique images is used in a robust voting procedure to label changes in existing buildings. Experimental evaluations using both the ISPRS benchmark datasets and Shenzhen datasets reveal that the proposed method outperforms the ResNet and EfficientNet networks by 5\% and 2\%, respectively, in terms of recall rate and precision. We demonstrate that the proposed method can successfully detect all changed buildings; therefore, only those marked as changed need to be manually checked during the pipeline updating procedure; this significantly reduces the manual quality control requirements. Moreover, ablation studies indicate that using depth data, feature pyramid modules, and multi-view voting strategies can lead to clear and progressive improvements.
Nonconcave entropies from generalized canonical ensembles
Creators: name: Costeniuc, Marius
name: Ellis, Richard S.
name: Touchette, Hugo
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: It is well-known that the entropy of the microcanonical ensemble cannot be calculated as the Legendre transform of the canonical free energy when the entropy is nonconcave. To circumvent this problem, a generalization of the canonical ensemble which allows for the calculation of nonconcave entropies was recently proposed. Here, we study the mean-field Curie-Weiss-Potts spin model and show, by direct calculations, that the nonconcave entropy of this model can be obtained by using a specific instance of the generalized canonical ensemble known as the Gaussian ensemble.
description: 5 pages, RevTeX4, 3 figures (best viewed in ps)
Casimir interaction between normal or superfluid grains in the Fermi sea
Creators: name: Wirzba, Andreas
name: Bulgac, Aurel
name: Magierski, Piotr
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Chaotic Dynamics (nlin.CD)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We report on a new force that acts on cavities (literally empty regions of space) when they are immersed in a background of non-interacting fermionic matter fields. The interaction follows from the obstructions to the (quantum mechanical) motions of the fermions caused by the presence of bubbles or other (heavy) particles in the Fermi sea, as, for example, nuclei in the neutron sea in the inner crust of a neutron star or superfluid grains in a normal Fermi liquid. The effect resembles the traditional Casimir interaction between metallic mirrors in the vacuum. However, the fluctuating electromagnetic fields are replaced by fermionic matter fields. We show that the fermionic Casimir problem for a system of spherical cavities can be solved exactly, since the calculation can be mapped onto a quantum mechanical billiard problem of a point-particle scattered off a finite number of non-overlapping spheres or disks. Finally we generalize the map method to other Casimir systems, especially to the case of a fluctuating scalar field between two spheres or a sphere and a plate under Dirichlet boundary conditions.
description: 8 pages, 2 figures, submitted to the Proceedings of QFEXT'05, Barcelona, Sept. 5-9, 2005
Decoherence at absolute zero
Creators: name: Sinha, Supurna
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We present an analytical study of the loss of quantum coherence at absolute zero. Our model consists of a harmonic oscillator coupled to an environment of harmonic oscillators at absolute zero. We find that for an Ohmic bath, the offdiagonal elements of the density matrix in the position representation decay as a power law in time at late times. This slow loss of coherence in the quantum domain is qualitatively different from the exponential decay observed in studies of high temperature environments.
description: Published in Physics Letters A
Gravitational Lensing of Pregalactic 21 cm Radiation
Creators: name: Metcalf, R. Benton
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Low-frequency radio observations of neutral hydrogen during and before the epoch of cosmic reionization will provide hundreds of quasi-independent source planes, each of precisely known redshift, if a resolution of ~ 1 arcminutes or better can be attained. These planes can be used to reconstruct the projected mass distribution of foreground material. A wide-area survey of 21 cm lensing would provide very sensitive constraints on cosmological parameters, in particular on dark energy. These are up to 20 times tighter than the constraints obtainable from comparably sized, very deep surveys of galaxy lensing although the best constraints come from combining data of the two types. Any radio telescope capable of mapping the 21cm brightness temperature with good frequency resolution (~ 0.05 MHz) over a band of width ~> 10 MHz should be able to make mass maps of high quality. If the reionization epoch is at z ~ 9 very large amounts of cosmological information will be accessible. The planned Square Kilometer Array (SKA) should be capable of mapping the mass with a resolution of a few arcminutes depending on the reionization history of the universe and how successfully foreground sources can be subtracted. The Low-Frequency Array (LOFAR) will be able to measure an accurate matter power spectrum if the same conditions are met.
description: prize wining contribution to proceedings of the Cosmology 2007 conference in Venice, 4 pages, one color figure
Optimising and comparing source extraction tools using objective segmentation quality criteria
Creators: name: Haigh, Caroline
name: Chamba, Nushkia
name: Venhola, Aku
name: Peletier, Reynier
name: Doorenbos, Lars
name: Watkins, Matthew
name: Wilkinson, Michael H. F.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: With the growth of the scale, depth, and resolution of astronomical imaging surveys, there is an increased need for highly accurate automated detection and extraction of astronomical sources from images. This also means there is a need for objective quality criteria, and automated methods to optimise parameter settings for these software tools. We present a comparison of several tools which have been developed to perform this task: namely SExtractor, ProFound, NoiseChisel, and MTObjects. In particular, we focus on evaluating performance in situations which present challenges for detection -- for example, faint and diffuse galaxies; extended structures, such as streams; and objects close to bright sources. Furthermore, we develop an automated method to optimise the parameters for the above tools. We present four different objective segmentation quality measures, based on precision, recall, and a new measure for the correctly identified area of sources. Bayesian optimisation is used to find optimal parameter settings for each of the four tools on simulated data, for which a ground truth is known. After training, the tools are tested on similar simulated data, to provide a performance baseline. We then qualitatively assess tool performance on real astronomical images from two different surveys. We determine that when area is disregarded, all four tools are capable of broadly similar levels of detection completeness, while only NoiseChisel and MTObjects are capable of locating the faint outskirts of objects. MTObjects produces the highest scores on all tests on all four quality measures, whilst SExtractor obtains the highest speeds. No tool has sufficient speed and accuracy to be well-suited to large-scale automated segmentation in its current form.
description: Accepted in Astronomy and Astrophysics. Second version 16 Nov 2020 with a change in the acknowledgements
On particle dynamics in AdS_{N+1} space-time
Creators: name: Dorn, Harald
name: Jorjadze, George
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We summarize part of a systematic study of particle dynamics on $AdS_{N+1}$ space-time based on Hamiltonian methods. New explicit UIR's of SO(2,N), defined on certain spaces of holomorphic functions, are constructed. The connection to some field theoretic results, including the construction of propagators, is discussed.
description: 8 pages, to appear in the proceedings of the 37th Int. Symp. Ahrenshoop on the Theory of Elementary Particles, Aug. 23-27, 2004, Berlin-Schm\"ockwitz
Evolution of the density PDF in star forming clouds: the role of gravity
Creators: name: Jaupart, Etienne
name: Chabrier, Gilles
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We derive an analytical theory of the PDF of density fluctuations in supersonic turbulence in the presence of gravity in star-forming clouds. The theory is based on a rigorous derivation of a combination of the Navier-Stokes continuity equations for the fluid motions and the Poisson equation for the gravity. It extends upon previous approaches first by including gravity, second by considering the PDF as a dynamical system, not a stationary one. We derive the transport equations of the density PDF, characterize its evolution and determine the density threshold above which gravity strongly affects and eventually dominates the dynamics of turbulence. We demonstrate the occurence of {\it two} power law tails in the PDF, with two characteristic exponents, corresponding to two different stages in the balance between turbulence and gravity. Another important result of this study is to provide a procedure to relate the observed {\it column density} PDFs to the corresponding {\it volume density} PDFs. This allows to infer, from the observation of column-densities, various physical parameters characterizing molecular clouds, notably the virial parameter. Furthermore, the theory offers the possibility to date the clouds in units of ${t}_{\rm coll}$, the time since a statistically significant fraction of the cloud started to collapse. The theoretical results and diagnostics reproduce very well numerical simulations and observations of star-forming clouds. The theory provides a sound theoretical foundation and quantitative diagnostics to analyze observations or numerical simulations of star-forming regions and to characterize the evolution of the density PDF in various regions of molecular clouds.
description: Accepted for publications in APJ Letters
Aspects of Graviton Detection: Graviton Emission and Absorption by Atomic Hydrogen
Creators: name: Boughn, Stephen
name: Rothman, Tony
Publisher: name: arXiv
Year: 2006
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Graviton absorption cross sections and emission rates for hydrogen are calculated by both semi-classical and field theoretic methods. We point out several mistakes in the literature concerning spontaneous emission of gravitons and related phenomena, some of which are due to a subtle issue concerning gauge invariance of the linearized interaction Hamiltonian.
description: 19 pages, no figures
Open source microscope add-on for structured illumination microscopy
Creators: name: Hannebelle, Mélanie
name: Raeth, Esther
Publisher: name: Zenodo
Year: 2023

description: Super-resolution techniques expand the abilities of researchers who have the knowledge and resources to either build or purchase a system. This excludes the part of the research community without these capabilities. Here we introduce the openSIM add-on to upgrade existing optical microscopes to Structured Illumination super-resolution Microscopes (SIM). The openSIM is an open-hardware system, designed and documented to be easily duplicated by other laboratories, making super-resolution modality accessible to facilitate innovative research. The add-on approach gives a performance improvement for pre-existing lab equipment without the need to build a completely new system.
Here we provide example datasets of different samples (100nm beads, fixed tubulin, zebrafish-embryo) including the raw data, reconstructed data with corresponding image acquisition and image reconstruction parameters.
The Multi-Field, Rapid-Turn Inflationary Solution
Creators: name: Aragam, Vikas
name: Paban, Sonia
name: Rosati, Robert
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: There are well-known criteria on the potential and field-space geometry for determining if slow-roll, slow-turn, multi-field inflation is possible. However, even though it has been a topic of much recent interest, slow-roll, rapid-turn inflation only has such criteria in the restriction to two fields. In this work, we generalize the two-field, rapid-turn inflationary attractor to an arbitrary number of fields. We quantify a limit, which we dub extreme turning, in which rapid-turn solutions may be found efficiently and develop methods to do so. In particular, simple results arise when the covariant Hessian of the potential has an eigenvector in close alignment with the gradient -- a situation we find to be common and we prove generic in two-field hyperbolic geometries. We verify our methods on several known rapid-turn models and search two type-IIA constructions for rapid-turn trajectories. For the first time, we are able to efficiently search for these solutions and even exclude slow-roll, rapid-turn inflation from one potential.
description: 30 pages, 8 figures. v2: added missed references
Disordered and ordered states of exactly solvable Ising-Heisenberg planar models with a spatial anisotropy
Creators: name: Strecka, Jozef
name: Jascur, Michal
Publisher: name: arXiv
Year: 2005
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Ground-state and finite-temperature properties of a special class of exactly solvable Ising-Heisenberg planar models are examined using the generalized decoration-iteration and star-triangle mapping transformations. The investigated spin systems exhibit an interesting quantum behaviour manifested in a remarkable geometric spin frustration, which appears notwithstanding the purely ferromagnetic interactions of the considered model systems. This kind of spin frustration originates from an easy-plane anisotropy in the XXZ Heisenberg interaction between nearest-neighbouring spins that favours ferromagnetic ordering of their transverse components, whereas their longitudinal components are aligned antiferomagnetically.
description: 6 pages, 4 figures, Presented at 15-th Conference of Czech and Slovak Physicist, Kosice, Slovakia, September 5-8, 2005