cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Insight into the Distribution of High-pressure Shock Metamorphism in Rubble-pile Asteroids
Creators: name: Güldemeister, Nicole
name: Moreau, Juulia-Gabrielle
name: Kohout, Tomas
name: Luther, Robert
name: Wünnemann, Kai
Publisher: name: Freie Universität Berlin
Year: 2022
Subjects: subject: Main belt asteroids
subject: Computational methods
subject: Asteroid dynamics
subject: Chondrites
subject: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::550 Geowissenschaften

description: AbstractShock metamorphism in ordinary chondrites allows for reconstructing impact events between asteroids in the main asteroid belt. Shock-darkening of ordinary chondrites occurs at the onset of complete shock melting of the rock (>70 GPa) or injection of sulfide and metal melt into the cracks within solid silicates (∼50 GPa). Darkening of ordinary chondrites masks diagnostic silicate features observed in the reflectance spectrum of S-complex asteroids so they appear similar to C/X-complex asteroids. In this work, we investigate the shock pressure and associated metamorphism pattern in rubble-pile asteroids at impact velocities of 4–10 km s−1. We use the iSALE shock physics code and implement two-dimensional models with simplified properties in order to quantify the influence of the following parameters on shock-darkening efficiency: impact velocity, porosity within the asteroid, impactor size, and ejection efficiency. We observe that, in rubble-pile asteroids, the velocity and size of the impactor are the constraining parameters in recording high-grade shock metamorphism. Yet, the recorded fraction of higher shock stages remains low (<0.2). Varying the porosity of the boulders from 10% to 30% does not significantly affect the distribution of pressure and fraction of shock-darkened material. The pressure distribution in rubble-pile asteroids is very similar to that of monolithic asteroids with the same porosity. Thus, producing significant volumes of high-degree shocked ordinary chondrites requires strong collision events (impact velocities above 8 km s−1 and/or large sizes of impactors). A large amount of asteroid material escapes during an impact event (up to 90%); however, only a small portion of the escaping material is shock-darkened (6%).
Machine learning technique for signal-background separation of nuclear interaction vertices in the CMS detector
Creators: name: Kropivnitskaya, Anna
Publisher: name: Zenodo
Year: 2020

description: The CMS inner tracking system is a fully silicon-based high precision detector. Accurate knowledge of the positions of active and inactive elements is important for simulating the detector, planning detector upgrades, and reconstructing charged particle tracks. Nuclear interactions of hadrons with the detector material create secondary vertices whose positions map the material with a sub-millimeter precision in situ, while the detector is collecting data from LHC collisions. A neural network (NN) with two hidden layers was used to separate secondary vertices due to combinatorial background from those arising from nuclear interactions with material. The NN was trained and tested on data from proton-proton collisions at a center-of-mass energy of 13 TeV, recorded in 2018 at the LHC. Supervised NN training is performed using Keras and Matplotlib in a Jupyter notebook. Secondary vertices in the training data are classified as signal or background, based on their geometrical position. Even though the variables used in training show only small differences between background and signal, the NN has impressive separation power. Tomographies of the CMS inner tracker detector before and after background cleaning are presented. Notebooks of the presentation.
Holographic Cusped Wilson loops in $q$-deformed $AdS_5\times S^5$ Spacetime
Creators: name: Bai, Nan
name: Chen, Hui-Huang
name: Wu, Jun-Bao
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper, minimal surface in $q$-deformed $AdS_5\times S^5$ with boundary a cusp is studied in detail. This minimal surface is dual to cusped Wilson loop in the dual field theory. We found that the area of the minimal surface has both logarithmic squared divergence and logarithmic divergence. The logarithmic squared divergence can not be removed by either Legendre transformation or the usual geometric substraction. We further make analytic continuation to the Minkowski signature %for the case without the jump and take the limit such that the two edges of the cusp become light-like and extract anomalous dimension from the coefficient of the logarithmic divergence. This anomalous dimension goes back smoothly to the results in the undeformed case when we take the limit that the deformation parameter goes to zero.
description: 18 pages, no figures
Pre-birth acquisition of personhood: Incremental accrual of attributes as the framework for individualization by serial and concurrently acting developmental factors
Creators: name: Hughes, Gavin C.
name: Hughes, Claude L.
Publisher: name: Frontiers Media S.A.
Year: 2023

description: Discrete events and processes influence development of individual humans. Attribution of personhood to any individual human being cannot be disconnected from the underlying biological events and processes of early human development. Nonetheless, the philosophical, sociological and legal components that are integral to the meaning of the term as commonly used cannot be deduced from biology alone. The challenge for biomedical scientists to inform discussion in this arena then rests on profiling the key biological events and processes that must be assessed when considering how one might objectively reason about the task of superimposing the concept of personhood onto the developing biological entity of a potential human being. Endogenous genetic and epigenetic events and exogenous developmental milieu processes diversify developmental trajectories of potential individual humans prior to livebirth. First, fertilization and epigenetic resetting of each individual's organismic clock to time zero (t = 0) at the gastrulation/primitive streak stage (day 15 of embryogenesis), are two discrete unseen biological events that impact a potential individual human's attributes. Second, those two discrete unseen biological events are immersed in the continuous developmental process spanning pre-fertilization and gestation, further driving individualization of diverse attributes of each future human before the third discrete and blatant biological event of parturition and livebirth. Exposures of the gravida to multiple diverse exogenous exposures means that morphogenesis and physiogenesis of every embryo/fetus has individualized attributes for its future human lifespan. Our proposed framework based on the biological discrete events and processes spanning pre-fertilization and prenatal development, implies that personhood should be incrementally attributed, and societal protections should be graduated and applied progressively across the pre-birth timespan.
A Survey on Technological Trends to Enhance Spectrum Efficiency in 6G Communications
Creators: name: Iyer, Sridhar
name: Patil, Anita
name: Bhairanatti, Shilpa
name: Halagatti, Soumya
name: Pandya, Rahul Jashvantbhai
Publisher: name: arXiv
Year: 2022
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Signal Processing (eess.SP)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: The research community has already identified that, by 2030, 5G networks will reach the capacity limits, and hence, will be inadequate to support next generation bandwidth-hungry, ubiquitous, intelligent services, and applications. Therefore, in view of sustaining the competitive edge of wireless technology and stratifying the next decade's communication requirements both, industry and research community have already begun conceptualizing the 6G technology. This article presents a detailed survey on the recent technological trends which address the capacity issues and enhance the spectrum-efficiency in 6G Communications. We present these trends in detail and then identify the challenges that need solutions before the practical deployment to realize 6G communications. Our survey article attempts to significantly contribute to initiating future research directions in the area of spectrum-efficiency in 6G communications.
Sweeteners Used by the Confectionery Industry: Their Competitive Position in the United States
Creators: name: Ballinger, Roy A.
name: Larkin, L. C.
name: Ballinger, Roy A.
name: Larkin, L. C.
Publisher: name: Unknown
Year: 1963
Subjects: Agricultural and Food Policy
Food Consumption/Nutrition/Food Safety
Industrial Organization

description: Excerpts from the report Summary: The confectionery industry--candy, candied fruits and other confectionery products, chewing gum, chocolate and cocoa products--uses a larger quantity of corn sirup, more than one-third of the total consumption, than any other food industry in the United States. It also uses nearly one-tenth of the sugar and more than one-twentieth of the dextrose consumed in the United States. The total quantity of sugar, corn sirup, and dextrose delivered to confectionery industry increased during the period 1952-61 at an average rate of about 25,000 tons a year, of which 20,000 tons were sugar, 5,000 corn sirup, and 360 dextrose. The increase in the use of these products was only slightly faster than the growth of population in the United States. Per capita use increased only about 6 percent from 1952 to 1961.
Multimodal cryoEM approaches enable reaching sub-nanometre resolutions in situ and modelling of known components in a high-torque flagellar motor
Creators: name: Drobnič, Tina
Publisher: name: Imperial College London
Year: 2023

description: We poorly understand how molecular components of life evolve. In absence of a fossil record, we rely on comparisons between contemporary protein complexes to make inferences about molecular evolution. Bacterial flagellar motors are structurally diverse motility devices, well-suited to evolutionary study. Motors across different lineages evolved varied elaborations on top of a highly conserved mechanistic core. These additional scaffolds make for wider motors, increasing torque output for navigating high-viscosity environments. Variety in presence and composition of scaffolds allow comparison between species, to understand how novel proteins contribute to motility and modify existing complexes. Towards understanding how new components evolve, I studied flagellar structure and phylogenetics in pathogen Campylobacter jejuni. Its high-torque motor contains an outer membrane-associated basal disk and a periplasmic scaffold. I used cryo-electron tomography in situ imaging to expand the list of proteins that make up the basal disk and periplasmic scaffold. Next, I reconstructed a sub-nanometre resolution cryo-electron microscopy map of the C. jejuni motor. I combined homology and de novo protein modelling to assemble a near-complete atomic model of the motor, building on my previous results. I validated the model by in vitro protein interactions and in situ imaging of deletion mutants. My model revealed how additional motor components assemble to enable high torque, and how pre-existing parts changed to accommodate this. Structures revealed that various components are likely homologous to contemporary enzymes and other non-flagellar proteins. Finally, I conducted a bioinformatics analysis, showing most proteins of the C. jejuni scaffold are unique to species within its phylum, Campylobacterota. I found the major basal disk protein is additionally present in δ-proteobacteria, and described a new closely related protein family. Combining my analysis with published results from our lab, I implicate δ-proteobacteria as possibly descendant from an ancestral motor before their divergence from Campylobacterota.
A new Monte Carlo method for dynamical evolution of non-spherical stellar systems
Creators: name: Vasiliev, Eugene
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We have developed a novel Monte Carlo method for simulating the dynamical evolution of stellar systems in arbitrary geometry. The orbits of stars are followed in a smooth potential represented by a basis-set expansion and perturbed after each timestep using local velocity diffusion coefficients from the standard two-body relaxation theory. The potential and diffusion coefficients are updated after an interval of time that is a small fraction of the relaxation time, but may be longer than the dynamical time. Thus our approach is a bridge between the Spitzer's formulation of the Monte Carlo method and the temporally smoothed self-consistent field method. The primary advantages are the ability to follow the secular evolution of shape of the stellar system, and the possibility of scaling the amount of two-body relaxation to the necessary value, unrelated to the actual number of particles in the simulation. Possible future applications of this approach in galaxy dynamics include the problem of consumption of stars by a massive black hole in a non-spherical galactic nucleus, evolution of binary supermassive black holes, and the influence of chaos on the shape of galaxies, while for globular clusters it may be used for studying the influence of rotation.
description: 13 pages; matches published paper
A longitudinal study of olfactory dysfunction and parosmia in mild COVID-19 cases
Creators: name: Ebert, Charles S.
name: Wohl, David
name: Onuorah, Princess
name: Kimple, Adam J.
name: Murr, Alexander
name: Bacon, Daniel R.
name: Thorp, Brian D.
name: Monk, Aurelia S.
name: Senior, Brent A.
name: Oakes, Jonathan
name: Wiesen, Christopher A.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2022

description: Background: COVID-19-related olfactory dysfunction (OD) can persist long after patients recover from acute infection, yet few studies have investigated the long-term progression of this complication. Moreover, existing studies are focused on hyposmia/anosmia but parosmia is becoming an increasingly recognized long-term symptom. Methods: We completed a longitudinal study about OD in individuals with mild cases of COVID-19. Participants completed a questionnaire and Brief Smell Identification Test (BSIT) one week, one month and one year after diagnosis. At one-year, participants completed an additional survey about parosmia. Results: We obtained questionnaires and psychophysical olfactory testing information from participants at one week (n=45), one month (n=38), and one year (n=33) post COVID-19 diagnosis. At one-year, 15.2% of participants had persistent OD and 66.7% of participants reported experiencing parosmia at some point following COVID-19 diagnosis. The mean onset of parosmia was 1.3 weeks (SD: 1.9 weeks) after diagnosis, although two patients reported delayed onset (>4 weeks after diagnosis). Eight patients (24.2%) reported ongoing parosmia one year after diagnosis. Of the patients whose parosmia resolved, the mean duration of symptoms was 7.2 weeks (SD: 7.3 weeks). Conclusion: Decreased sense of smell associated with COVID-19 infection has received significant recognition in both the media and in the medical literature. Symptoms of OD and parosmia were common in our patients with COVID-19. Hyposmia, anosmia, and parosmia, all decrease quality of life, necessitating continued research to understand the pathogenesis, course of symptoms, and possible treatment for these complications.
Structure, Thermodynamics, and Raman Spectroscopy of Rhenium-Doped Bulk MoS$_2$ from First Principles
Creators: name: Guerrero, Enrique
name: Strubbe, David A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Doping MoS$_2$ with Re is known to alter the electronic, structural, and tribological properties. Re-doped MoS$_2$ has been previously mainly studied in monolayer or few-layer form, but can also be relevant for applications in many-layer or bulk form. In this work, we use density functional theory to explore the structure, phase stability, and Raman spectrum of bulk Re-doped MoS$_2$. We consider the possibility of the Re dopant existing at different locations and provide experimentally distinguishable characteristics of the most likely sites: Mo-substitution and tetrahedral (t-) intercalation. We demonstrate and benchmark a general approach to calculate Raman spectra of doped materials with metallic densities of states by using atomic Raman tensors from the pristine material. Applying this method to the metallic Re-doped structures, we find characteristic shifts in the Raman-active peaks depending on Re dopant position: redshifts in both A$_{\rm 1g}$ and E$_{\rm 2g}^1$ peaks in the t-intercalated case versus a redshift for A$_{\rm 1g}$ and blueshift (sometimes accompanied by a smaller redshifted peak) for E$_{\rm 2g}^1$ peaks in the Mo-substituted case, which can be used to identify the dopant sites in experimental samples. We analyze the interactions giving rise to these shifts.
description: 31 pages, 8 figures
On Kossakowski construction of positive maps in matrix algebras
Creators: name: Chruściński, Dariusz
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We provide a further analysis of the class of positive maps proposed ten years ago by Kossakowski. In particular we propose a new parametrization which reveals an elegant geometric structure and an interesting interplay between group theory and a certain class of positive maps.
description: Dedicated to Andrzej Kossakowski on his 75th birthday
Rates of capture of stars by supermassive black holes in non-spherical galactic nuclei
Creators: name: Vasiliev, Eugene
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We consider the problem of star consumption by supermassive black holes in non-spherical (axisymmetric, triaxial) galactic nuclei. We review the previous studies of the loss-cone problem and present a novel simulation method which allows to separate out the collisional (relaxation-related) and collisionless (related to non-conservation of angular momentum) processes and determine their relative importance for the capture rates in different geometries. We show that for black holes more massive than 10^7 Msun, the enhancement of capture rate in non-spherical galaxies is substantial, with even modest triaxiality being capable of keeping the capture rate at the level of few percent of black hole mass per Hubble time.
description: 21 pages; matches published paper
CMB Constraints On The Thermal WIMP Mass And Annihilation Cross Section
Creators: name: Steigman, Gary
Publisher: name: arXiv
Year: 2015
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A thermal relic, often referred to as a weakly interacting massive particle (WIMP), is a particle produced during the early evolution of the Universe whose present (relic) abundance depends only on its mass and its thermally averaged annihilation cross section (annihilation rate factor) sigma*v_ann. Late time WIMP annihilation has the potential to affect the cosmic microwave background (CMB) power spectrum. Current observational constraints on the absence of such effects provide bounds on the mass and the annihilation cross section of relic particles that may, but need not be dark matter candidates. For a WIMP that is a dark matter candidate, the CMB constraint sets an upper bound to the annihilation cross section, leading to a lower bound to its mass that depends on whether or not the WIMP is its own antiparticle. For a self-conjugate WIMP, m_min = 50f GeV, where f is an electromagnetic energy efficiency factor. For a non self-conjugate WIMP, the minimum mass is a factor of two larger. For a WIMP that is a subdominant component of the dark matter density there is no bound on its mass and the upper bound to its annihilation cross section imposed by the CMB transforms into a lower bound to its annihilation cross section. These results are outlined and quantified here using the latest CMB constraints for a stable, symmetric (equal number of particles and antiparticles), WIMP whose annihilation is s-wave dominated, and for particles that are, or are not, their own antiparticle.
description: 10 pages, 7 figures, added references
Ecosystem synergies, change and orchestration
Creators: name: Cao, Zhe (Selina)
Publisher: name: Imperial College London
Year: 2023

description: This thesis investigates ecosystem synergies, change, and orchestration. The research topics are motivated by my curiosity, a fragmented research landscape, theoretical gaps, and new phenomena that challenge extant theories. To address these motivators, I conduct literature reviews to organise existing studies and identify their limited assumptions in light of new phenomena. Empirically, I adopt a case study method with abductive reasoning for a longitudinal analysis of the Alibaba ecosystem from 1999 to 2020. My findings provide an integrated and updated conceptualisation of ecosystem synergies that comprises three distinctive but interrelated components: 1) stack and integrate generic resources for efficiency and optimisation, 2) empower generative changes for variety and evolvability, and 3) govern tensions for sustainable growth. Theoretically grounded and empirically refined, this new conceptualisation helps us better understand the unique synergies of ecosystems that differ from those of alternative collective organisations and explain the forces that drive voluntary participation for value co-creation. Regarding ecosystem change, I find a duality relationship between intentionality and emergence and develop a phasic model of ecosystem sustainable growth with internal and external drivers. This new understanding challenges and extends prior discussions on their dominant dualism view, focus on partial drivers, and taken-for-granted lifecycle model. I propose that ecosystem orchestration involves systematic coordination of technological, adoption, internal, and institutional activities and is driven by long-term visions and adjusted by re-visioning. My analysis reveals internal orchestration's important role (re-envisioning, piloting, and organisation architectural reconfiguring), the synergy and system principles in designing adoption activities, and the expanding arena of institutional activities. Finally, building on the above findings, I reconceptualise ecosystems and ecosystem sustainable growth to highlight multi-stakeholder value creation, inclusivity, long-term orientation and interpretative approach. The thesis ends with discussing the implications for practice, policy, and future research.
An Economic Appraisal of the 1961 Feed Grain Program
Creators: name: Vermeer, James
name: Vermeer, James
Publisher: name: Unknown
Year: 1963
Subjects: Agricultural and Food Policy
Crop Production/Industries
Environmental Economics and Policy
Land Economics/Use

description: Excerpts from the report Summary: Following a 9-year buildup in feed grain stocks, the 1961 Feed Grain Program was enacted by Congress to enable farmers to maintain their incomes while reducing production of corn and grain sorghums. The program offered farmers incentive payments to divert at least 20 percent of their corn and grain sorghum acreage to conservation uses. It also offered them support prices on their normal yield on the reduced acreage at a national average price of $1.20 a bushel for corn and $1.93 a hundredweight for grain sorghum. About 1,200 farmers in 8 areas were selected for study. The sample in each area included about 75 participants in the 1961 Feed Grain Program and 75 nonparticipants selected at random from the records in the county offices of Agricultural Stabilization and Conservation Service. In personal interviews with these farmers, information was obtained on size of farms, acreages of cropland and land in corn and grain sorghum, productivity of the land, personal characteristics of the operators and their families, and other factors that were presumed to have some bearing on participation in the program.
Boundary Corrected Multi-scale Fusion Network for Real-time Semantic Segmentation
Creators: name: Jiang, Tianjiao
name: Jin, Yi
name: Liang, Tengfei
name: Wang, Xu
name: Li, Yidong
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences
subject: I.4.6

description: Image semantic segmentation aims at the pixel-level classification of images, which has requirements for both accuracy and speed in practical application. Existing semantic segmentation methods mainly rely on the high-resolution input to achieve high accuracy and do not meet the requirements of inference time. Although some methods focus on high-speed scene parsing with lightweight architectures, they can not fully mine semantic features under low computation with relatively low performance. To realize the real-time and high-precision segmentation, we propose a new method named Boundary Corrected Multi-scale Fusion Network, which uses the designed Low-resolution Multi-scale Fusion Module to extract semantic information. Moreover, to deal with boundary errors caused by low-resolution feature map fusion, we further design an additional Boundary Corrected Loss to constrain overly smooth features. Extensive experiments show that our method achieves a state-of-the-art balance of accuracy and speed for the real-time semantic segmentation.
description: 5 pages, 3 figures
Efficient Two-Stage Analysis for Complex Trait Association with Arbitrary Depth Sequencing Data
Creators: name: Yuan, Shuai
name: Wu, Cong
name: Guo, Zifang
name: Xu, Zheng
name: Yan, Song
name: Chen, Sixia
name: Li, Yun
Publisher: name: MDPI
Year: 2023

description: Sequencing-based genetic association analysis is typically performed by first generating genotype calls from sequence data and then performing association tests on the called genotypes. Standard approaches require accurate genotype calling (GC), which can be achieved either with high sequencing depth (typically available in a small number of individuals) or via computationally intensive multi-sample linkage disequilibrium (LD)-aware methods. We propose a computationally efficient two-stage combination approach for association analysis, in which single-nucleotide polymorphisms (SNPs) are screened in the first stage via a rapid maximum likelihood (ML)-based method on sequence data directly (without first calling genotypes), and then the selected SNPs are evaluated in the second stage by performing association tests on genotypes from multi-sample LD-aware calling. Extensive simulation- and real data-based studies show that the proposed two-stage approaches can save 80% of the computational costs and still obtain more than 90% of the power of the classical method to genotype all markers at various depths d≥2.
AEON January 2022 Research Cruise Report
Creators: name: Warren, Joseph
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 370801
subject: Biological oceanography
classificationCode: 370802
subject: Chemical oceanography
classificationCode: 370803
subject: Physical oceanography

description: The AEON network concentrates all observation assets in the Gulf of Maine and totals 5 observation nodes. Node locations are determined based on an in-depth analysis of current regional assets and collaborations, bathymetry and associated sound propagation models, location historical and predicted oceanographic features, and ecosystem relevance. Four cruises are planned; an initial deployment cruise, 6-month maintenance cruise, and two 12-month maintenance/recovery cruises. Ancillary data is collected during each cruise to adequately address the question of temporal and spatial data correlation for both the active and passive datasets.See: https://eos.unh.edu/aeon
Evolution of binary supermassive black holes and the final-parsec problem
Creators: name: Vasiliev, Eugene
Publisher: name: arXiv
Year: 2014
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: I review the evolution of binary supermassive black holes and focus on the stellar-dynamical mechanisms that may help to overcome the final-parsec problem - the possible stalling of the binary at a separation much larger than is required for an efficient gravitational wave emission. Recent N-body simulations have suggested that a departure from spherical symmetry in the nucleus of the galaxy may keep the rate of interaction of stars with the binary at a high enough level so that the binary continues to shrink rather rapidly. However, a major problem of all these simulations is that they do not probe the regime where collisionless effects are dominant - in other words, the number of particles in the simulation is still not sufficient to reach the asymptotic behaviour of the system. I present a novel Monte Carlo method for simulating both collisional and collisionless evolution of non-spherical stellar systems, and apply it for the problem of binary supermassive black hole evolution. I show that in triaxial galaxies the final-parsec problem is largely non-existent, while in the axisymmetric case it seems to still exist in the limit of purely collisionless regime relevant for real galaxies, but disappears in the N-body simulations where the feasible values of N are still too low to get rid of collisional effects.
description: 8 pages; proceedings of IAU symposium #312, "Star clusters and black holes in galaxies across cosmic time" (refs updated)
Constraining Higher Derivative Supergravity with Scattering Amplitudes
Creators: name: Wang, Yifan
name: Yin, Xi
Publisher: name: arXiv
Year: 2015
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study supersymmetry constraints on higher derivative deformations of type IIB supergravity by consideration of superamplitudes. Combining constraints of on-shell supervertices and basic results from string perturbation theory, we give a simple argument for the non-renormalization theorem of Green and Sethi, and some of its generalizations.
description: 9 pages, 2 figures; references add
January 2022 Research Cruise Report
Creators: name: Warren, Joseph
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 370801
subject: Biological oceanography
classificationCode: 370802
subject: Chemical oceanography
classificationCode: 370803
subject: Physical oceanography

description: The AEON network concentrates all observation assets in the Gulf of Maine and totals 5 observation nodes. Node locations are determined based on an in-depth analysis of current regional assets and collaborations, bathymetry and associated sound propagation models, location historical and predicted oceanographic features, and ecosystem relevance. Four cruises are planned; an initial deployment cruise, 6-month maintenance cruise, and two 12-month maintenance/recovery cruises. Ancillary data is collected during each cruise to adequately address the question of temporal and spatial data correlation for both the active and passive datasets.See: https://eos.unh.edu/aeon
Ferromagnetic resonance and Andreev spectroscopy on exotic superconducting states
Creators: name: Chan, Alex Kevin Kar Tsung
Publisher: name: Imperial College London
Year: 2023

description: This thesis examines two aspects of superconducting phenomena by employing two different experimental techniques. The first phenomenon is two-gap superconductivity, and the second phenomenon is long-range proximity induced spin-triplet (LRPST) superconductivity. Using point contact Andreev reflection (PCAR) spectroscopy, evidence for two-gap superconductivity was investigated in Mo1-xRex alloys. Recent specific heat capacity measurements claim the existence of two-gap superconductivity in these alloys. PCAR spectroscopy can identify superconducting energy gaps, and was used here to see if two-gap superconductivity could be confirmed. Direct observation of two distinct energy gaps in spectra measured at 4.2 K and 2 K was not found. However, comparing the temperature dependent PCAR parameters extracted from a single-gap fit with a two-gap fit to the spectra offered some interesting insight. PCAR spectroscopy was also used to investigate the second phenomenon. In superconductor/ferromagnet (S/F) structures, it is possible to create LRPST with long-range penetration in F by having a spatially inhomogeneous magnetic layer at the interface. This interface is known as a ‘spin-active’ interface, where spin-mixing and spin-rotation processes can occur. Stimulated by claims that a paramagnetic Meissner effect, carried by spin-triplets, can be observed in Nb/Ho/Au multilayers, PCAR was used here to see if signatures of proximity induced spin-triplets could be observed. Theoretical calculations have predicted that spin-mixing at the spin-active interface can lead to Andreev bound states that appear as sub-gap features in electrical conductance spectra. Furthermore, LRPST may also give rise to a peak in the density of states at zero energy. Finally, a ferromagnetic resonance (FMR) technique was used to see if LRPST could be detected in a non-equilibrium system. Nb/Cr/Fe/Cr/Nb multilayers were studied, where it was found that the key signature of a spin-triplet channel was observed only when the correct conditions were satisfied in the presence of an externally applied field.
Machine learning algorithms for fluid mechanics
Creators: name: Özbay, Ali Girayhan
Publisher: name: Imperial College London
Year: 2023

description: Neural networks have become increasingly popular in the field of fluid dynamics due to their ability to model complex, high-dimensional flow phenomena. Their flexibility in approximating continuous functions without any preconceived notion of functional form makes them a suitable tool for studying fluid dynamics. The main uses of neural networks in fluid dynamics include turbulence modelling, flow control, prediction of flow fields, and accelerating high-fidelity simulations. This thesis focuses on the latter two applications of neural networks. First, the application of a convolutional neural network (CNN) to accelerate the solution of the Poisson equation step in the pressure projection method for incompressible fluid flows is investigated. The CNN learns to approximate the Poisson equation solution at a lower computational cost than traditional iterative solvers, enabling faster simulations of fluid flows. Results show that the CNN approach is accurate and efficient, achieving significant speedup in the Taylor-Green Vortex problem. Next, predicting flow fields past arbitrarily-shaped bluff bodies from point sensor and plane velocity measurements using neural networks is focused on. A novel conformal-mapping-aided method is devised to embed geometry invariance for the outputs of the neural networks, which is shown to be critical for achieving good performance for flow datasets incorporating a diverse range of geometries. Results show that the proposed methods can accurately predict the flow field, demonstrating excellent agreement with simulation data. Moreover, the flow field predictions can be used to accurately predict lift and drag coefficients, making these methods useful for optimizing the shape of bluff bodies for specific applications.
Component periods of non-principal-axis rotation and their manifestations in the lightcurves of asteroids and bare cometary nuclei
Creators: name: Samarasinha, Nalin H.
name: Mueller, Beatrice E. A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Lightcurve observations of asteroids and bare cometary nuclei are the most widely used observational tool to derive the rotational parameters. Therefore, an in-depth understanding of how component periods of dynamically excited non-principal axis (NPA) rotators manifest in lightcurves is a crucial step in this process. We investigated this with the help of numerically generated lightcurves of NPA rotators with component periods known a priori. The component periods of NPA rotation were defined in terms of two widely used yet complementary conventions. We derive the relationships correlating the component rotation periods in the two conventions. These relationships were then used to interpret the periodicity signatures present in the simulated lightcurves and rationalize them in either convention.
description: 31 pages, 7 figure, 2 tables. This version replaces the earlier version and typos are corrected. The conclusions are unchanged
A CLT for weighted time-dependent uniform empirical processes
Creators: name: Yang, Yuping
Publisher: name: arXiv
Year: 2014
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60F05 (primary), 60F17 (secondary)

description: For a uniform process $\{ X_t: t\in E\}$ (by which $X_t $ is uniformly distributed on $(0,1)$ for $t\in E$) and a function $w(x)>0$ on $(0,1)$, we give a sufficient condition for the weak convergence of the empirical process based on $\{ w(x)(\mathbb{1}_{X_t\leq x} -x): t\in E, x\in [0,1]\}$ in $\ell^\infty(E\times [0,1])$. When specializing to $w(x)\equiv 1$ and assuming strict monotonicity on the marginal distribution functions of the input process, we recover a result of Kuelbs, Kurtz, and Zinn (2013). In the last section, we give an example of the main theorem.
Age-Grade School Progress of Farm and Nonfarm Youth: 1960
Creators: name: Cowhig, James D.
name: Cowhig, James D.
Publisher: name: Unknown
Year: 1963
Subjects: Labor and Human Capital
Research Methods/ Statistical Methods

description: Excerpt from the report Highlights: Results of the 1950 and 1960 Censuses are used to compare the school progress of farm and nonfarm children in 1960 and to describe the changes that occurred over the decade. The basis of comparison is the enrollment of children of specific ages in specific grades. For children at each single age between 8 and 17, there is a two-grade span which includes the grades in which most children of a given age are enrolled. These two grades are referred to as the ones “expected" for a given age. Children enrolled in grades below those expected for their age are said to be “retarded" scholastically; those in grades above the expected are said to be "accelerated" scholastically.
Attractive Hubbard model with disorder and the generalized Anderson theorem
Creators: name: Kuchinskii, E. Z.
name: Kuleeva, N. A.
name: Sadovskii, M. V.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Using the generalized DMFT+Sigma approach we have studied disorder influence on single-particle properties of the normal phase and superconducting transition temperature in attractive Hubbard model. The wide range of attractive potentials U was studied - from the weak coupling region, where both the instability of the normal phase and superconductivity are well described by BCS model, towards the strong coupling region, where superconducting transition is due to Bose-Einstein condensation (BEC) of compact Cooper pairs, formed at temperatures much higher than the temperature of superconducting transition. We have studied two typical models of conduction band with semi-elliptic and flat densities of states, appropriate for three-dimensional and two-dimensional systems respectively. For semi-elliptic density of states disorder influence on all single-particle properties (e.g. density of states) is universal for arbitrary strength of electronic correlations and disorder and is due only to the general disorder widening of conduction band. In the case of flat density of states universality is absent in general case, but still the disorder influence is due mainly to band widening and universal behavior is restored for large enough disorder. Using the combination of DMFT+Sigma and Nozieres - Schmitt-Rink approximations we have studied disorder influence upon superconducting transition temperature T_c for the range of characteristic values of U and disorder, including the BCS-BEC crossover region and the limit of strong coupling. Disorder can either suppress T_c (in the weak coupling region) or significantly increase T_c (in strong coupling region). However in all cases the generalized Anderson theorem is valid and all changes of superconducting critical temperature are essentially due only to the general disorder widening of the conduction band.
description: 9 pages, 4 figures, accepted by JETP
Theory for planetary exospheres: I. Radiation pressure effect on dynamical trajectories
Creators: name: Beth, Arnaud
name: Garnier, Philippe
name: Toublanc, Dominique
name: Dandouras, Iannis
name: Mazelle, Christian
Publisher: name: arXiv
Year: 2015
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The planetary exospheres are poorly known in their outer parts, since the neutral densities are low compared with the instruments detection capabilities. The exospheric models are thus often the main source of information at such high altitudes. We present a new way to take into account analytically the additional effect of the radiation pressure on planetary exospheres. In a series of papers, we present with an Hamiltonian approach the effect of the radiation pressure on dynamical trajectories, density profiles and escaping thermal flux. Our work is a generalization of the study by Bishop and Chamberlain (1989). In this first paper, we present the complete exact solutions of particles trajectories, which are not conics, under the influence of the solar radiation pressure. This problem was recently partly solved by Lantoine and Russell (2011) and completely by Biscani and Izzo (2014). We give here the full set of solutions, including solutions not previously derived, as well as simpler formulations for previously known cases and comparisons with recent works. The solutions given may also be applied to the classical Stark problem (Stark,1914): we thus provide here for the first time the complete set of solutions for this well-known effect in term of Jacobi elliptic functions.
5G Network Slice Isolation
Creators: name: Wong, Stan
name: Han, Bin
name: Schotten, Hans D.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cryptography and Security (cs.CR)
subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: This article reveals an adequate comprehension of basic defense, security challenges, 2 and attack vectors in deploying multi-network slicing. Network slicing is a revolutionary concept 3 of providing mobile network on-demand and expanding mobile networking business and services 4 to a new era. The new business paradigm and service opportunities are encouraging vertical 5 industries to join and develop their own mobile network capabilities for enhanced performances 6 that are coherent with their applications. However, a number of security concerns are also raised 7 in this new era. In this article, we focus on the deployment of multi-network slicing with multi8 tenancy. We identify the security concerns, and discuss about the defense approaches such as 9 network slice isolation and insulation in a multi-layer network slicing security model. Also, we 10 identify the importance to appropriately select the network slice isolation points, and propose 11 a generic framework to optimize the isolation policy regarding the implementation cost while 12 guaranteeing the security and performance requirements.
description: Accepted by MDPI Network on 03.03.2022 for publication
Performance and degradation studies of IrOx for polymer electrolyte membrane water electrolyser applications
Creators: name: Murawski, James
Publisher: name: Imperial College London
Year: 2023

description: In order to enable the scale-up of the proton exchange membrane (PEM) electrolyser technology to the terawatt level, improvements in anode catalyst utilisation are necessary. State of the art PEM electrolysers typically use IrOx to catalyse the oxygen evolution at the anode; however, further improvements in iridium utilisation need to be made without compromising performance or device lifetime. The research community has only recently started to attempt systematic benchmarking of catalyst stability. Short term electrochemical methods alone are insufficient to predict catalyst degradation; they can both underestimate and overestimate catalyst durability. In this work, detailed methods to track trends in catalyst stability using conventional techniques such as rotating disk electrode studies are conducted and supported by complementary techniques. These complementary techniques include inductively coupled plasma – mass spectrometry to track performance and stability during accelerated stress testing. These methods were then assessed by testing a series of IrOx nanoparticles both commercially obtained and synthesized via a variant of the Adams Fusion method. Catalysts synthesized via Adams Fusion method demonstrated significant increases in stability with approximately an order of magnitude difference in dissolved Ir observed between those synthesized at 400 oC and 500 oC. This correlates with change between amorphous (400 oC) and crystalline (500 oC, 600 oC) structure with less significant improvements in stability being seen between 500 oC and 600 oC. Increasing annealing temperature also correlated with reduced surface area and reduced activity. The comparison of different lower potential limits during stability testing also demonstrated increased dissolution upon decreasing lower potential limit. Therefore, the observations indicate that electrochemical reduction plays a large role in the heightened dissolution observed from potential cycling. Several operando techniques are also demonstrated for investigation of the fundamental understanding of activity and stability of IrOx nanoparticle catalysts using electrochemistry mass spectrometry and optical absorption spectroscopy to probe gas phase products and reaction intermediates. The results of these studies show an optically observable species on the nanoparticle catalysts that begins to occur approximately 100 mV less positive than oxygen onset, defined as the initial potential at which evolved oxygen can be directly observed either electrochemically or via the use of in-situ techniques, and tracks into the oxygen evolving region. Additionally, the differences observed between oxygen onset observed from mass spectrometry between amorphous and crystalline catalysts track with results observed from optical signals.
Bulk photospin effect: Calculation of electric spin susceptibility to second order in an electric field
Creators: name: Fregoso, Benjamin M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We compute the electric spin susceptibility of Bloch electrons with spin-orbit coupling to second order. We find that it is possible to generate a nonequilibrium spin polarization in the bulk of non-magnetic inversion-symmetric materials using linearly polarized electric fields, but the process depends on interband coherence and produces heating. It may be possible to avoid heating with circular polarization in certain scenarios. The standard Edelstein effect and spin orientation effects are recovered in appropriate limits within the formalism. Finally, the electric spin susceptibility of metals has contributions proportional to spin multipole moments of the Fermi sea that dominate the low frequency spin response.
description: 12 pages, 1 figure, references updated, published version