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Laser frequency noise suppression is a critical requirement for the Laser Interferometer Space Antenna (LISA) mission to detect gravitational waves. The baseline laser stabilization is achieved using cavity pre-stabilization and a post-processing technique called Time-Delay-Interferometry (TDI). To enhance the margins for TDI, alternate laser locking schemes should be investigated. A novel stabilisation blending the excellent stability of the arm with the existing cavity reference has been shown theoretically to meet the first-generation TDI margins. This locking system was designed to be implemented as a firmware change and have minimal or no changes to the LISA hardware. This paper experimentally verifies the hybrid laser locking technique by utilizing two references - an optical cavity, and an interferometer with delay imparted using 10 km of optical fiber. The results indicate the viability of the combination of arm-cavity locking system for LISA. They show the key benefits envisioned by this technique; suppression of the cavity fluctuations by the arm sensor (by 21 dB in this demonstration) and reduction of Doppler pulling of the laser frequency, a key technical challenge for arm locking., Comment: 11 pages, 13 figures

Plane-wave electrons undergo momentum transfer as they scatter off a target in overlapping spherical waves. The transferred momentum leads to target structural information to be encoded in angle and energy differential scattering. For symmetric, periodic or structured targets this can engender diffraction in the electron intensity both in real (angular) and in momentum space. With the example of elastic scattering from C60 we show this simultaneous manifestation of diffraction signatures. The simulated angle-momentum diffractograms can be imaged in experiments with a two-dimensional detector and an energy-tunable electron gun. The result may inspire invention of technology to extend scopes of electron diffraction from molecules and nanostructures, open a direction of electron crystallography using the momentum-differential diffraction, and motivate an approach to control the time delay between the pump laser-pulse and the probe electron-pulse by tuning the electron impact-speed in ultrafast electron diffraction experiments., Comment: 6 pages, 5 figures

Time delay in a projectile-target scattering is a fundamental tool in understanding their interactions by probing the temporal domain. The present study focuses on computing and analyzing the Eisenbud-Wigner-Smith (EWS) time delay in low energy elastic e C60 scattering. The investigation is carried out in the framework of a non-relativistic partial wave analysis (PWA) technique. The projectile-target interaction is described in (1) Density Functional Theory (DFT) and (2) Annular Square Well (ASW) static model, and their final results are compared in details. The impact of polarization on resonant and non-resonant time delay is also investigated.

We compute the heavy quarkonium complex potential in an arbitrary magnetic field strength generated in the relativistic heavy-ion collision. First, the one-loop gluon polarization tensor is obtained in the presence of an external, constant, and homogeneous magnetic field using the Schwinger proper time formalism in Euclidean space. The gluon propagator is computed from the gluon polarization tensor, and it is used to calculate the dielectric permittivity in the presence of the magnetic field in the static limit. The modified dielectric permittivity is then used to compute the heavy quarkonium complex potential. We find that the heavy quarkonium complex potential is anisotropic in nature, which depends on the angle between the quark-antiquark ($Q\bar{Q}$) dipole axis and the direction of the magnetic field. We discuss the effect of the magnetic field strength and the angular orientation of the dipole on the heavy quarkonium potential. We discuss how the magnetic field influences the thermal widths of quarkonium states. Further, we also discuss the limitation of the strong-field approximation as done in literature in the light of heavy-ion observables, as the effect of the magnetic field is very nominal to the quarkonium potential., Comment: 13 pages, 6 figures, Published version

We investigate the nature of the complex retarded potential of a heavy quarkonium moving in a hot and dense static deconfined nuclear medium. The well-known concept of the retarded potential in electrodynamics is extended to the context of the heavy-quark by modifying the static vacuum Cornell potential through Lorentz transformation to the static frame of the medium. The resulting potential in the vacuum is further corrected to incorporate the screening effect offered by the thermal medium. To do so, the retarded Cornell potential is modified by the dielectric function of the static quark-gluon plasma (QGP) medium. We present the numerical results for the real and imaginary parts of the potential along with the analytical expression of the potential approximated by a small velocity limit. Finally, we present the thermal width of quarkonia in the QGP medium derived using the imaginary part of the potential and study its dependence on velocity and temperature., Comment: 10 pages, 7 figures

Scientific models hold the key to better understanding and predicting the behavior of complex systems. The most comprehensive manifestation of a scientific model, including crucial assumptions and parameters that underpin its usability, is usually embedded in associated source code and documentation, which may employ a variety of (potentially outdated) programming practices and languages. Domain experts cannot gain a complete understanding of the implementation of a scientific model if they are not familiar with the code. Furthermore, rapid research and development iterations make it challenging to keep up with constantly evolving scientific model codebases. To address these challenges, we develop a system for the automated creation and human-assisted curation of a knowledge graph of computable scientific models that analyzes a model's code in the context of any associated inline comments and external documentation. Our system uses knowledge-driven as well as data-driven approaches to identify and extract relevant concepts from code and equations from textual documents to semantically annotate models using domain terminology. These models are converted into executable Python functions and then can further be composed into complex workflows to answer different forms of domain-driven questions. We present experimental results obtained using a dataset of code and associated text derived from NASA's Hypersonic Aerodynamics website.

Slide presentations are an effective and efficient tool used by the teaching community for classroom communication. However, this teaching model can be challenging for blind and visually impaired (VI) students. The VI student required personal human assistance for understand the presented slide. This shortcoming motivates us to design a Classroom Slide Narration System (CSNS) that generates audio descriptions corresponding to the slide content. This problem poses as an image-to-markup language generation task. The initial step is to extract logical regions such as title, text, equation, figure, and table from the slide image. In the classroom slide images, the logical regions are distributed based on the location of the image. To utilize the location of the logical regions for slide image segmentation, we propose the architecture, Classroom Slide Segmentation Network (CSSN). The unique attributes of this architecture differs from most other semantic segmentation networks. Publicly available benchmark datasets such as WiSe and SPaSe are used to validate the performance of our segmentation architecture. We obtained 9.54 segmentation accuracy improvement in WiSe dataset. We extract content (information) from the slide using four well-established modules such as optical character recognition (OCR), figure classification, equation description, and table structure recognizer. With this information, we build a Classroom Slide Narration System (CSNS) to help VI students understand the slide content. The users have given better feedback on the quality output of the proposed CSNS in comparison to existing systems like Facebooks Automatic Alt-Text (AAT) and Tesseract.

Recent AI governance research has focused heavily on the analysis of strategy papers and ethics guidelines for AI published by national governments and international bodies. Meanwhile, subnational institutions have also published documents on Artificial Intelligence, yet these have been largely absent from policy analyses. This is surprising because AI is connected to many policy areas, such as economic or research policy, where the competences are already distributed between the national and subnational level. To better understand the current dynamics of AI governance, it is essential to consider the context of policy making beyond the federal government. Although AI may be considered a new policy field, it is created, contested and ultimately shaped within existing political structures and dynamics. We therefore argue that more attention should be dedicated to subnational efforts to shape AI and present initial findings from our case study of Germany. Analyzing AI as a policy field on different levels of government will contribute to a better understanding of the developments and implementations of AI strategies in different national contexts., Comment: Working paper

This paper presents a novel method for laser frequency stabilisation in the Laser Interferometer Space Antenna (LISA) mission by locking a laser to two stable length references - the arms of the interferometer and an on-board optical cavity. The two references are digitally fused using carefully designed control systems, attempting minimal or no changes to the baseline LISA mission hardware. The interferometer arm(s) provides the most stable reference available in the LISA science band (0.1 mHz - 1 Hz), while the cavity sensor's wide-band and linear readout enables additional control system gain below and above the LISA band. The main technical issue with this dual sensor approach is the undesirable slow laser frequency pulling which couples into the control system with the imperfect knowledge of the Doppler shift of the light due to relative spacecraft motion along the LISA arm. This paper outlines requirements on the Doppler shift knowledge to maintain the cavity well within the resonance when activating the fused control system. Two Doppler shift estimation methods are presented that use the already on-board measurements, the inter-spacecraft interferometer link (the main science measurement), and the absolute inter-spacecraft laser ranging system. Both methods reach the required precision after a few thousand seconds of measurement integration. The paper demonstrates an approach to initialise and engage the proposed laser stabilization system, starting from free-running laser and ending with the dual sensor frequency control system. The results show that the technique lowers the residual laser frequency noise in the LISA science band by over 3 orders of magnitude, potentially allowing the requirements on Time-Delay-Interferometry (TDI) to be relaxed - possibly to the point where first-generation TDI may be sufficient., Comment: 17 pages, 15 figures

In meteor physics the luminous efficiency ${\tau}$ is used to convert the meteor's magnitude to the corresponding meteoroid's mass. However, lack of sufficiently accurate verification methods or adequate laboratory tests leave this parameter to be controversially discussed. In this work meteor/fireball data obtained by the Fireball Recovery and InterPlanetary Observation Network (FRIPON) was used to calculate the masses of the pre-atmospheric meteoroids which could in turn be compared to the meteor brightnesses to assess their luminous efficiencies. For that, deceleration-based formulas for the mass computation were used. We have found ${\tau}$-values, as well as the shape change coefficients, of 294 fireballs with determined masses in the range of $10^{-6}$ kg - $100$ kg. The derived ${\tau}$-values have a median of ${\tau}_{median}$ = 2.17 %. Most of them are on the order of 0.1 % - 10 %. We present how our values were obtained, compare them with data reported in the literature, and discuss several methods. A dependence of ${\tau}$ on the pre-atmospheric velocity of the meteor, $v_e$, is noticeable with a relation of ${\tau}=0.0023 \cdot v_e^{2.3}$. The higher luminous efficiency of fast meteors could be explained by the higher energy released. Fast meteoroids produce additional emission lines that radiate more efficiently in specific wavelengths due to the appearance of the so-called second component of higher temperature. Furthermore, a dependence of ${\tau}$ on the initial meteoroid mass, $M_e$, was found, with negative linear behaviour in log-log space: ${\tau}=0.48 \cdot M_e^{-0.47}$. This implies that the radiation of smaller meteoroids is more efficient.

Our chapter presents a scoping review of published scientific studies or case studies of scientific studies that utilise both citizen scientists and Internet of Things devices. Specifically, we selected studies where the authors had included at least a short discussion of the ethical issues encountered during the research process. Having conducted a search of five databases (IEEE Xplore, Scopus, Web of Science, ProQuest, and PubMed), we identified 631 potential results. Following abstract and title screening, and then full text eligibility assessment, we identified 34 published articles that matched our criteria. We then analysed the full text for these articles inductively and deductively, coding ethical issues into three main categories. These categories were autonomy and data privacy, data quality, and intellectual property. We also analysed the full text of these articles to see what strategies researchers took to resolve these ethical issues, as well as any legal implications raised. Following this analysis, our discussion provides recommendations for researchers who wish to integrate citizen scientists and Internet of Things devices into their research. First, all citizen science projects should integrate a data privacy protocol to protect the confidentiality of participants. Secondly, scientific researchers should consider any potential issues of data quality, including whether compromises might be required, before establishing a project. Finally, all intellectual property issues should be clarified both at the start of the project and during its lifecycle. Researchers should also consider any ethical issues that might flow from the use of commercially available Internet of Things devices for research., Comment: Authors' version; 17 pages, 4 tables