cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A Supersymmetric SYK-like Tensor Model
Creators: name: Peng, Cheng
name: Spradlin, Marcus
name: Volovich, Anastasia
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We consider a supersymmetric SYK-like model without quenched disorder that is built by coupling two kinds of fermionic N=1 tensor-valued superfields, "quarks" and "mesons". We prove that the model has a well-defined large-N limit in which the (s)quark 2-point functions are dominated by mesonic "melon" diagrams. We sum these diagrams to obtain the Schwinger-Dyson equations and show that in the IR, the solution agrees with that of the supersymmetric SYK model.
description: 29 pages, 19 figures. v2: 3 references and more details of the computation in section 3.1 are added
The Feyn-Structure of Yangian Symmetry
Creators: name: Loebbert, Florian
name: Mathur, Harshad
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Yangian-type differential operators are shown to constrain Feynman integrals beyond the restriction to integrable graphs. In particular, we prove that all position-space Feynman diagrams at tree level feature a Yangian level-one momentum symmetry as long as their external coordinates are distinct. This symmetry is traced back to a set of more elementary bilocal operators, which annihilate the integrals. In dual momentum space, the considered Feynman graphs represent multi-loop integrals without `loops of loops', generalizing for instance the family of so-called train track or train track network diagrams. The extension of these results to integrals with massive propagators on the boundary of the Feynman graph is established. When specializing to the dual conformal case, where propagator powers sum up to the spacetime dimension at each position-space vertex, the symmetry extends to the full dual conformal Yangian. Hence, our findings represent a generalization of the statements on the Yangian symmetry of Feynman integrals beyond integrability and reveal its origin lying in a set of more elementary bilocal annihilators. Previous applications of the Yangian suggest to employ the resulting differential equations for bootstrapping multi-loop integrals beyond the dual conformal case. The considered bilocal constraints on Feynman integrals resemble the definition of conformal partial waves via Casimir operators, but are based on a different algebraic structure.
description: 34 pages, v2: references added, typo corrected
An Erdös-Révész type law of the iterated logarithm for reflected fractional Brownian motion
Creators: name: Dębicki, K.
name: Kosiński, K. M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60F15, 60G70 (Primary), 60G22 (Secondary)

description: Let $B_H=\{B_H(t):t\in\mathbb R\}$ be a fractional Brownian motion with Hurst parameter $H\in(0,1)$. For the stationary storage process $Q_{B_H}(t)=\sup_{-\infty f(t)\, \text{ i.o.})$ equals 0 or 1. Using this criterion we find that, for a family of functions $f_p(t)$, such that $z_p(t)=\mathbb P(\sup_{s\in[0,f_p(t)]}Q_{B_H}(s)>f_p(t))/f_p(t)=\mathscr C(t\log^{1-p} t)^{-1}$, for some $\mathscr C>0$, $\mathbb P(Q_{B_H}(t) > f_p(t)\, \text{ i.o.})= 1_{\{p\ge 0\}}$. Consequently, with $ξ_p (t) = \sup\{s:0\le s\le t, Q_{B_H}(s)\ge f_p(s)\}$, for $p\ge 0$, $\lim_{t\to\infty}ξ_p(t)=\infty$ and $\limsup_{t\to\infty}(ξ_p(t)-t)=0$ a.s. Complementary, we prove an Erdös--Révész type law of the iterated logarithm lower bound on $ξ_p(t)$, i.e., $\liminf_{t\to\infty}(ξ_p(t)-t)/h_p(t) = -1$ a.s., $p>1$; $\liminf_{t\to\infty}\log(ξ_p(t)/t)/(h_p(t)/t) = -1$ a.s., $p\in(0,1]$, where $h_p(t)=(1/z_p(t))p\log\log t$.
description: arXiv admin note: text overlap with arXiv:1606.01502
Chirp Excitation
Creators: name: Khaneja, Navin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The paper describes the design of broadband chirp excitation pulses in NMR. We first develop a three stage model for understanding chirp excitation in NMR. We then show how a chirp $π$ pulse can be used to refocus the phase of the chirp excitation pulse. The resulting magnetization still has some phase dispersion in it. We show how a combination of two chirp $π$ pulses instead of one can be used to eliminate this dispersion, leaving behind a small residual phase dispersion. The excitation pulse sequence presented here allow exciting arbitrary large bandwidths without increasing the peak rf-amplitude. Although methods presented in this paper have appeared elsewhere, we present complete analytical treatment that elucidates the working of these methods.
Chiral Vortical Effect for Bosons
Creators: name: Avkhadiev, Artur
name: Sadofyev, Andrey V.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The thermal contribution to the chiral vortical effect is believed to be related to the axial anomaly in external gravitational fields. We use the universality of the spin-gravity interaction to extend this idea to a wider set of phenomena. We consider the Kubo formula at weak coupling for the spin current of a vector field and derive a novel anomalous effect caused by the medium rotation: the chiral vortical effect for bosons. The effect consists in a spin current of vector bosons along the angular velocity of the medium. We argue that it has the same anomalous nature as in the fermionic case and show that this effect provides a mechanism for helicity transfer, from flow helicity to magnetic helicity.
description: 6 pages, 1 figure, version accepted in PRD
Structures of Nichols (braided) Lie algebras of diagonal type
Creators: name: Wu, Weicai
name: Wang, Jing
name: Zhang, Shouchuan
name: Zhang, Yao-Zhong
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics
subject: 16W30, 22E60, 05L25

description: Let $V$ be a braided vector space of diagonal type. Let $\mathfrak B(V)$, $\mathfrak L^-(V)$ and $\mathfrak L(V)$ be the Nichols algebra, Nichols Lie algebra and Nichols braided Lie algebra over $V$, respectively. We show that a monomial belongs to $\mathfrak L(V)$ if and only if that this monomial is connected. We obtain the basis for $\mathfrak L(V)$ of arithmetic root systems and the dimension for $\mathfrak L(V)$ of finite Cartan type. We give the sufficient and necessary conditions for $\mathfrak B(V) = F\oplus \mathfrak L^-(V)$ and $\mathfrak L^-(V)= \mathfrak L(V)$. We obtain an explicit basis of $\mathfrak L^ - (V)$ over quantum linear space $V$ with $\dim V=2$.
description: 23 pages. Version to appear in Journal of Lie Theory
Anisotropic Compacts Stars on Paraboloidal Spacetime with Linear Equation of State
Creators: name: Thomas, V. O.
name: Pandya, D. M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: New exact solutions of Einstein's field equations (EFEs) by assuming linear equation of state, $ p_r = α(ρ- ρ_R) $ where $ p_r $ is the radial pressure and $ ρ_R $ is the surface density, are obtained on the background of a paraboloidal spacetime. By assuming estimated mass and radius of strange star candidate 4U 1820-30, various physical and energy conditions are used for estimating the range of parameter $ α$. The suitability of the model for describing pulsars like PSR J1903+327, Vela X-1, Her X-1 and SAX J1804.3658 has been explored and respective ranges of $ α$, for which all physical and energy conditions are satisfied throughout the distribution, are obtained.
description: 10 pages, 12 figures, 1 table
Vortex-core structure in a mixture of Bose and Fermi superfluids
Creators: name: Pan, Jian-Song
name: Zhang, Wei
name: Yi, Wei
name: Guo, Guang-Can
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study a single quantized vortex in the fermionic component of a mixture of Fermi superfluid and Bose-Einstein condensate. As the density ratio between the boson and the fermion components is tuned, we identify a transition in the vortex-core structure, across which fermions in the vortex core become completely depleted even in the weak-coupling Bardeen-Cooper-Schrieffer regime. This is accompanied by changes in key properties of the vortex state, as well as by the localization of the Bose-Einstein condensate in the vortex core. The transition in the vortex-core structure can be experimentally probed in Bose-Fermi superfluid mixtures by detecting the size and visibility of the vortices.
description: 7 pages + 6 figures
A Mass Transference Principle for systems of linear forms and its applications
Creators: name: Allen, Demi
name: Beresnevich, Victor
Publisher: name: arXiv
Year: 2017
Subjects: subject: Number Theory (math.NT)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics
subject: 11J83, 28A78, 11J13, 11K60

description: In this paper we establish a general form of the Mass Transference Principle for systems of linear forms conjectured in [1]. We also present a number of applications of this result to problems in Diophantine approximation. These include a general transference of Lebesgue measure Khintchine-Groshev type theorems to Hausdorff measure statements. The statements we obtain are applicable in both the homogeneous and inhomogeneous settings as well as allowing transference under any additional constraints on approximating integer points. In particular, we establish Hausdorff measure counterparts of some Khintchine-Groshev type theorems with primitivity constraints recently proved by Dani, Laurent and Nogueira [8].
description: 35 pages, some typos from the previous version have been corrected and the proofs of Corollary 1 and Lemma 4 have been updated
Tunable Half-metallic Magnetism in Atom-thin Holey Two-dimensional C$_2$N Monolayer
Creators: name: Gong, Sai
name: Wan, Wenhui
name: Guan, Shan
name: Tai, Bo
name: Liu, Chang
name: Fu, Botao
name: Yang, Shengyuan A.
name: Yao, Yugui
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Exploring two-dimensional (2D) materials with magnetic ordering is a focus of current research. It remains a challenge to achieve tunable magnetism in a material of one-atom-thickness without introducing extrinsic magnetic atoms or defects. Here, based on first-principles calculations, we propose that tunable ferromagnetism can be realized in the recently synthesized holey 2D C$_2$N ($h$2D-C$_2$N) monolayer via purely electron doping that can be readily achieved by gating. We show that owing to the prominent van Hove singularity in the band structure, the material exhibits ferromagnetism even at a small doping level. Remarkably, over a wide doping range of 4$\times$10$^{13}$/cm$^2$ to 8$\times$10$^{13}$/cm$^2$, the system becomes half-metallic, with carriers fully spin-polarized. The estimated Curie temperature can be up to 320 K. Besides gating, we find that the magnetism can also be effectively tuned by lattice strain. Our result identifies $h$2D-C$_2$N as the first material with single-atom-thickness that can host gate-tunable room-temperature half-metallic magnetism, suggesting it as a promising platform to explore nanoscale magnetism and flexible spintronic devices.
description: 12 pages, 5 figures
An architecture for efficient gravitational wave parameter estimation with multimodal linear surrogate models
Creators: name: O'Shaughnessy, Richard
name: Blackman, Jonathan
name: Field, Scott E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The recent direct observation of gravitational waves has further emphasized the desire for fast, low-cost, and accurate methods to infer the parameters of gravitational wave sources. Due to expense in waveform generation and data handling, the cost of evaluating the likelihood function limits the computational performance of these calculations. Building on recently developed surrogate models and a novel parameter estimation pipeline, we show how to quickly generate the likelihood function as an analytic, closed-form expression. Using a straightforward variant of a production-scale parameter estimation code, we demonstrate our method using surrogate models of effective-one-body and numerical relativity waveforms. Our study is the first time these models have been used for parameter estimation and one of the first ever parameter estimation calculations with multi-modal numerical relativity waveforms, which include all l <= 4 modes. Our grid-free method enables rapid parameter estimation for any waveform with a suitable reduced-order model. The methods described in this paper may also find use in other data analysis studies, such as vetting coincident events or the computation of the coalescing-compact-binary detection statistic.
description: 10 pages, 3 figures, and 1 table
Ray and Ray and Liz
Creators: name: Billingham, Richard
Publisher: name: Middlesex University
Year: 2015

description: Ray and Ray & Liz - A multiple component output comprising of:
(1) Ray (2015) 
A gallery installation exhibited internationally
(2) Ray & Liz (2018)
A multi-award winning and critically acclaimed feature film created for global theatrical release and mass market digital platforms
Both works were written and directed by Richard Billingham and produced by Jacqui Davies. The Director of Photography for both works was Daniel Landin.
Asymptotic safety in three-dimensional SU(2) Group Field Theory: evidence in the local potential approximation
Creators: name: Carrozza, Sylvain
name: Lahoche, Vincent
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the functional renormalization group of a three-dimensional tensorial Group Field Theory (GFT) with gauge group SU(2). This model generates (generalized) lattice gauge theory amplitudes, and is known to be perturbatively renormalizable up to order 6 melonic interactions. We consider a series of truncations of the exact Wetterich--Morris equation, which retain increasingly many perturbatively irrelevant melonic interactions. This tensorial analogue of the ordinary local potential approximation allows to investigate the existence of non-perturbative fixed points of the renormalization group flow. Our main finding is a candidate ultraviolet fixed point, whose qualitative features are reproduced in all the truncations we have checked (with up to order 12 interactions). This may be taken as evidence for an ultraviolet completion of this GFT in the sense of asymptotic safety. Moreover, this fixed point has a single relevant direction, which suggests the presence of two distinct infrared phases. Our results generally support the existence of GFT phases of the condensate type, which have recently been conjectured and applied to quantum cosmology and black holes.
description: 43 pages, many figures; v2: minor corrections
Teacher Quality and the Implementation of STEM Curricular for Modern Society.pdf
Creators: name: Inyang, Mary  Imo
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 399999
subject: Other education not elsewhere classified

description: The effective implementation of Science, Technology, Engineering and Mathematics (STEM) curricular largely depends on the STEM teachers. In this paper, teacher quality is examined as it affects effective implementation of the STEM curricular. Features that enhance teacher quality are discussed under teacher qualification, teacher characteristics and teacher practices. The deficiencies observed in STEM teacher continuous professional development, access to new technologies, infrastructural development, poor quality of enrolment in teacher education, low numbers of graduates and poor education funding was discussed under major areas of concern. Finally the paper examines essential tips like increased education funding by government, improved quality of prospective teachers for admission and continuous professional development as steps that can improve teacher quality and help enhance STEM curricular implementation.
Féeton ($B-L$ Gauge Boson) Dark Matter Testable in Future Direct Detection Experiments
Creators: name: Cheng, Yu
name: Sheng, Jie
name: Yanagida, Tsutomu T.
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this paper, we revisit the féeton (gauge boson of $U(1)_{B-L}$ symmetry) dark matter scenario, and first point out the $U(1)$ gauge symmetry can be a linear combination of the $B-L$ and the SM hypercharge gauge symmetries. With the redefinition of $B-L$ charge of fermions, the coupling between electron and féeton can be enhanced. After showing the parameter space required from the DM stability and cosmic production, we discuss the potential for verifying them in dark matter direct detection experiments. The results show that future experiments, such as SuperCDMS, have a sensitivity to reach the féeton DM region consistent with its cosmic production.
description: 13 pages, 2 figures
Mettre des IdRef dans votre SI : s'orienter dans l'offre de service de l'Abes
Creators: name: Mistral, François
name: Vathaire, Jean-Baptise de
name: Dornbusch, Joachim
Publisher: name: Zenodo
Year: 2023
Subjects: identifiant
IdRef

description: Session proposée dans le cadre des Journées Abes 2023. Injecter des identifiants, notamment des IdRef, dans vos bases permet l’interopérabilité par rebonds et passerelles. Si les API de l’Abes sont une assurance de valeur ajoutée, encore faut-il se repérer au sein d’une offre foisonnante. Illustrée de réalisations récentes par deux partenaires (Cairn.info et Paris1), cette session vous fournira une boussole pour naviguer en toute aise et avec de l’inspiration! En tant que professionnel de l’informatique document
Cosmological Solutions with Charged Black Holes
Creators: name: Bibi, Rashida
name: Clifton, Timothy
name: Durk, Jessie
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We consider the problem of constructing cosmological solutions of the Einstein-Maxwell equations that contain multiple charged black holes. By considering the field equations as a set of constraint and evolution equations, we construct exact initial data for N charged black holes on a hypersphere. This corresponds to the maximum of expansion of a cosmological solution, and provides sufficient information for a unique evolution. We then consider the specific example of a universe that contains eight charged black holes, and show that the existence of non-zero electric charge reduces the scale of the cosmological region of the space. These solutions generalize the Majumdar-Papapetrou solutions away from the extremal limit of charged black holes, and provide what we believe to be some of the first relativistic calculations of the effects of electric charge on cosmological backreaction.
description: 14 pages, 2 figures
Boosting Asynchronous Decentralized Learning with Model Fragmentation
Creators: name: Biswas, Sayan
name: Kermarrec, Anne-Marie
name: Marouani, Alexis
name: Pires, Rafael
name: Sharma, Rishi
name: de Vos, Martijn
Publisher: name: arXiv
Year: 2024
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Decentralized learning (DL) is an emerging technique that allows nodes on the web to collaboratively train machine learning models without sharing raw data. Dealing with stragglers, i.e., nodes with slower compute or communication than others, is a key challenge in DL. We present DivShare, a novel asynchronous DL algorithm that achieves fast model convergence in the presence of communication stragglers. DivShare achieves this by having nodes fragment their models into parameter subsets and send, in parallel to computation, each subset to a random sample of other nodes instead of sequentially exchanging full models. The transfer of smaller fragments allows more efficient usage of the collective bandwidth and enables nodes with slow network links to quickly contribute with at least some of their model parameters. By theoretically proving the convergence of DivShare, we provide, to the best of our knowledge, the first formal proof of convergence for a DL algorithm that accounts for the effects of asynchronous communication with delays. We experimentally evaluate DivShare against two state-of-the-art DL baselines, AD-PSGD and Swift, and with two standard datasets, CIFAR-10 and MovieLens. We find that DivShare with communication stragglers lowers time-to-accuracy by up to 3.9x compared to AD-PSGD on the CIFAR-10 dataset. Compared to baselines, DivShare also achieves up to 19.4% better accuracy and 9.5% lower test loss on the CIFAR-10 and MovieLens datasets, respectively.
description: Accepted to appear in the Proceedings of the ACM Web Conference 2025 (WWW '25)
Laplace equations, Lefschetz properties and line arrangements
Creators: name: Di Gennaro, Roberta
name: Ilardi, Giovanna
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: In this note we generalize the main result in [DIV: R. Di Gennaro, G. Ilardi, J. Valles, Singular hypersurfaces characterizing the Lefschetz properties J. Lond. Math. Soc. (2) 89 (2014), no. 1, 194-212] on artinian ideals failing Lefschetz properties, varieties satisfying Laplace equations and existence of suitable singular hypersurfaces. Moreover we characterize the minimally generation of ideals generated by power of linear forms by the configuration of their dual points in the projective plane and we use this result to improve some propositions on line arrangments and Strong Lefschetz property (SLP) at range 2 in [DIV]. The starting point was an example in [CHMN: D. Cook II, B. Harbourne, J. Migliore, U. Nagel, Line arrangements and configurations of points with an unusual geometric property (2017), arXiv:1602.02300v2]. Finally we show the equivalence among failing SLP, Laplace equations and some unexpected curves in [CHMN].
description: Please cite this article in press as J. Pure Appl. Algebra (2017), https://doi.org/10.1016/j.jpaa.2017.10.013
Proof of Komlós's conjecture on Hamiltonian subsets
Creators: name: Kim, Jaehoon
name: Liu, Hong
name: Sharifzadeh, Maryam
name: Staden, Katherine
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: Komlós conjectured in 1981 that among all graphs with minimum degree at least $d$, the complete graph $K_{d+1}$ minimises the number of Hamiltonian subsets, where a subset of vertices is Hamiltonian if it contains a spanning cycle. We prove this conjecture when $d$ is sufficiently large. In fact we prove a stronger result: for large $d$, any graph $G$ with average degree at least $d$ contains almost twice as many Hamiltonian subsets as $K_{d+1}$, unless $G$ is isomorphic to $K_{d+1}$ or a certain other graph which we specify.
description: 33 pages, to appear in Proceedings of the London Mathematical Society
The concentration of potentially toxic elements (PTEs) in fruit juices: a global systematic review, meta-analysis and probabilistic health risk assessment
Creators: name: Khazaei, Salman
name: Ghane, Elaheh Talebi
name: Bashirian, Saeid
name: Mehri, Fereshteh
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Biochemistry
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 60506 Virology

description: This study was conducted to estimate the containation of potentially toxic elements (PTEs) in fruit juice, e.g. apple, grape, mango, orange, peach, and pineapple. The related studies regarding the concentration of PTEs in fruit juice which have been published in recommended databases including PubMed, Embase, Web of Science and Scopus from 7 January 1969 to 20 February 2020 were analysed. Also, the health risk assessment for consumers due to PTEs ingestion via consuming various fruit juices was evaluated using target hazard quotient (THQ). Among 701 retrieved citations in the identification step, 44 articles were included in this conducted meta-analysis. In this context, the overall rank order of PTEs mean concentrations in the fruit juices were as follows: iron (Fe) >zinc (Zn)> copper (Cu)> lead (Pb) >nickel (Ni)> cadmium (Cd)> in apple and orange, Cu> Zn> Pb in grape, Fe> Zn>Cu>Ni>Cd>Pb in mango, Fe>Zn>Cu>Ni >Pb>Cd in peach and Cu>Zn>Cd>Ni>As in pineapple. Our results showed that the highest concentration of Pb and Cd were 0.075 and 0.204 mg/kg in orange and pineapple, respectively. The concentration of As in apple and orange juices was similar (0.003 mg/kg). Regarding Ni, Cu, Zn and Fe, the highest concentrations were 0.188, 0.508, 0.562 and 16.712 mg/kg in peach, mango and pineapple, respectively. The assessment of non-carcinogenic risk indicated that risk pattern was different in various countries. In addition, fruit juice consumers did not have a significant risk because of the ingestion of PTEs.
Development of a sustainable ternary magnetic nanocomposite GCNI for efficient and synergistic photodegradation of Rhodamine B under solar irradiation: kinetic and mechanistic studies
Creators: name: Thakur, Monika
name: Singh, Harminder
name: Rajput, Jaspreet Kaur
name: Kumar, Rupesh
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Biophysics
subject: Space Science
subject: 29999 Physical Sciences not elsewhere classified
subject: FOS: Physical sciences
subject: Medicine
subject: Molecular Biology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences

description: In this study, a novel sunlight-active ternary magnetic nano-photocatalyst GCNI (Nanozero valent Iron @ Graphene oxide and Chitosan support) was fabricated. This easily retrievable magnetic nanocomposite was prepared by depositing NZVI (Nano Zero Valent Iron, Fe0) over binary GO-CS in seven different compositions for its best optimisation in the solar-light-promoted degradation of RhB. NC (Nano Composite) was characterised by SEM demonstrating their surface morphology. Further characterisation and properties of NC were also studied using XRD, FT-IR, VSM and BET and EDS techniques. The efficacy of the NC was investigated for the removal of RhB in comparison to binary GO-CS and bare NZVI. GCNI 1:1:3 was found to be the best suitable photocatalyst showing synergistic effect in the photodegradation of RhB under given conditions of pH, concentration and time. The mechanism of dye removal and degradation was further discovered by UV-VIS and mass spectroscopy techniques. FT-IR and XRD results of fresh and treated GCNI successively corroborated the mechanism. The sorption kinetics of RhB on to GCNI was found to be described by the pseudo-second-order kinetic equation. The parameters such as dye concentration, pH and the reaction time are varied to understand the effective removal of RhB in wastewater. The outcomes exhibited the highly efficient; up to 99.4% of dye removal, easy magnetic separation of photocatalyst, excellent reusability up-to 87.5% till six consecutive cycles, synergistic effect in adsorption and photo-degradation of dye.
Bridging the gap between algorithmic and learned index structures
Creators: name: Hadian, Ali
Publisher: name: Imperial College London
Year: 2022

description: Index structures such as B-trees and bloom filters are the well-established petrol engines of database systems. However, these structures do not fully exploit patterns in data distribution. To address this, researchers have suggested using machine learning models as electric engines that can entirely replace index structures. Such a paradigm shift in data system design, however, opens many unsolved design challenges. More research is needed to understand the theoretical guarantees and design efficient support for insertion and deletion. In this thesis, we adopt a different position: index algorithms are good enough, and instead of going back to the drawing board to fit data systems with learned models, we should develop lightweight hybrid engines that build on the benefits of both algorithmic and learned index structures. The indexes that we suggest provide the theoretical performance guarantees and updatability of algorithmic indexes while using position prediction models to leverage the data distributions and thereby improve the performance of the index structure. We investigate the potential for minimal modifications to algorithmic indexes such that they can leverage data distribution similar to how learned indexes work. In this regard, we propose and explore the use of helping models that boost classical index performance using techniques from machine learning. Our suggested approach inherits performance guarantees from its algorithmic baseline index, but at the same time it considers the data distribution to improve performance considerably. We study single-dimensional range indexes, spatial indexes, and stream indexing, and show that the suggested approach results in range indexes that outperform the algorithmic indexes and have comparable performance to the read-only, fully learned indexes and hence can be reliably used as a default index structure in a database engine. Besides, we consider the updatability of the indexes and suggest solutions for updating the index, notably when the data distribution drastically changes over time (e.g., for indexing data streams). In particular, we propose a specific learning-augmented index for indexing a sliding window with timestamps in a data stream. Additionally, we highlight the limitations of learned indexes for low-latency lookup on real- world data distributions. To tackle this issue, we suggest adding an algorithmic enhancement layer to a learned model to correct the prediction error with a small memory latency. This approach enables efficient modelling of the data distribution and resolves the local biases of a learned model at the cost of roughly one memory lookup.
Model Independent Constraints on Charges of New Particles
Creators: name: Chway, Dongjin
name: Dermisek, Radovan
name: Jung, Tae Hyun
name: Kim, Hyung Do
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Any particle that is charged under $SU(3)_C$ and $U(1)_{EM}$ can mediate the $gg \rightarrow γγ$ process through loops. Near the threshold for the new particle pair production, gauge boson exchanges necessitate the resummation of ladder diagrams. We discuss the leading log order matching of the one-loop result with non-relativistic effective theory resummed result. We show how the diphoton invariant mass spectrum varies depending on decay width, color representation and electric charge of the new particle. The exclusion limits on the product of $SU(3)_C$ and $U(1)_{EM}$ charges of the new scalar or fermion particle are obtained from current LHC data.
description: 34 pages, 21 figures, Appendix A and B added. More discussion on exclusion limit added
Finite-time quantum entanglement in propagating squeezed microwaves
Creators: name: Fedorov, Kirill G.
name: Pogorzalek, S.
name: Heras, U. Las
name: Sanz, M.
name: Yard, P.
name: Eder, P.
name: Fischer, M.
name: Goetz, J.
name: Xie, E.
name: Inomata, K.
name: Nakamura, Y.
name: Di Candia, R.
name: Solano, E.
name: Marx, A.
name: Deppe, F.
name: Gross, R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Two-mode squeezing is a fascinating example of quantum entanglement manifested in cross-correlations of incompatible observables between two subsystems. At the same time, these subsystems themselves may contain no quantum signatures in their self-correlations. These properties make two-mode squeezed (TMS) states an ideal resource for applications in quantum communication. Here, we generate propagating microwave TMS states by a beam splitter distributing single mode squeezing emitted from distinct Josephson parametric amplifiers along two output paths. We experimentally study the fundamental dephasing process of quantum cross-correlations in continuous-variable propagating TMS microwave states and accurately describe it with a theory model. In this way, we gain the insight into finite-time entanglement limits and predict high fidelities for benchmark quantum communication protocols such as remote state preparation and quantum teleportation.
title: Photovoltaic Project Development in Montenegro: a case study
Creators: name: Strigl, Anna
Publisher: name: TU Wien
Year: 2023
Subjects: subject: climate change
subject: montenegro
subject: solar power
subject: photovoltaic
subject: case study
subject: pv project

description: Due to climate change and unreliable natural gas supplies, renewable energy has become increasingly important. The current share of electricity generated by solar power in Montenegro is negligible. However, the country has a high solar potential which is suitable for developing PV projects. Consequently, this thesis will elab- orate on the following research questions: (1)”What are the main steps involved in developing a feasible PV project in Montenegro, and what external factors need to be considered during the process?”, (2)”What is the outcome of a cost-benefit ana- lysis for developing a PV project in Montenegro?” and (3)”What are the challenges and opportunities for the PV sector in Montenegro?” The first part of the thesis gives a fundamental background about PV technology and the project development framework. After basic knowledge has been given, a case study was conducted on how a PV project can be developed in Montenegro. An analysis of the most im- portant political, economic, social, technical, environmental, and legal settings has been made. In addition to this, a stakeholder analysis and cost-benefit analysis were carried out. In order to get local insights, insightful interviews with specialists from Montenegro were done. The result is a guideline for a project developer coming to Montenegro with the aim of developing a PV project. Further interpretation shows that the project is financially feasible but the external factors have a crucial impact on the outcome of the project. Political instabilities, missing legislative and support- ing incentives, a lack of best-practices, corruption, and informal market structures outweigh the favorable environmental and financial conditions. A first-mover ad- vantage can be seized by experienced developers but should be closely managed with good insurance and risk management. Nevertheless, if the country manages to get back on track with a clear political direction and takes action regarding the promotion of renewable energy systems, it could turn Montenegro into a favorable environment for project developers and transform the country into an innovative renewable energy hub on its path to become an EU member state.
Understanding the impact of an expanded neutral current pion production model on long-baseline oscillation analyses at T2K
Creators: name: Naseby, Charles
Publisher: name: Imperial College London
Year: 2022

description: As long-baseline neutrino oscillation experiments continue to collect data, systematic uncertainties will play a more significant role in limiting measurement precision. The work presented here examines one such source of systematic uncertainty in the T2K (Tokai to Kamioka) experiment, neutral current neutrino interactions producing pions. The process of expanding the oscillation analysis with an expanded cross-section treatment is described, in conjunction with the addition of SK neutral current π0 control samples. The analysis makes use of a Markov Chain Monte Carlo method to investigate the impact of these additions on both the oscillation parameter measurement and other parameters of the fit. Finally, an investigation of future systematic uncertainties of relevance to the next-generation long-baseline neutrino experiment Hyper-Kamiokande is made. This focuses on the potential provided by a proposed new near-detector to constrain the leading systematic uncertainty in HK’s measurement of the neutrino CP violating phase δCP.
Measurements of the Quantum Yield of Silicon using Geiger-mode Avalanching Photodetectors
Creators: name: Lewis, Harry
name: Mahtab, Mahsa
name: Retiere, Fabrice
name: Croix, Austin De St.
name: Raymond, Kurtis
name: Henriksson-Ward, Maia
name: Morrison, Nicholas
name: Zhang, Aileen
name: Capra, Andrea
name: Underwood, Ryan
Publisher: name: arXiv
Year: 2024
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Accurate characterization of quantum yield is crucial to the reconstruction of energy depositions in silicon at the eV scale. This work presents a new method for experimentally calculating quantum yield using vacuum UV-sensitive silicon photomultipliers (SiPMs), which can be used to determine the probabilities that a UV photon absorbed in a silicon crystal will produce one, two, or three electron-hole pairs. Results are presented which fully constrain the distribution at photon energies up to 7.75eV. This method works by exploiting the saturation of photon detection efficiency which occurs when these devices are biased sufficiently high above their avalanche breakdown voltage. The measured quantum yield values are lower than those that have been previously reported by experimental data and modelling -- this is expected to impact the sensitivity of experiments searching for light dark matter through direct detection in semiconductors, and should also be taken into account when characterizing the performance of UV photodetectors with high quantum efficiency. Measurements have been taken using a Hamamatsu VUV4 and an FBK VUV-HD3 device, showing good agreements between devices, and at a range of temperatures from 163-233K. The validity of the method is assessed using supplementary measurements of absolute photon detection efficiency, and an additional novel method of measuring average quantum yield using DC current-voltage measurements of SiPMs is presented and used for corroboration.
description: 13 pages, 11 figures
Linear stability and numerical analysis of dipolar vortices and topographic flows
Creators: name: Davies, Jack
Publisher: name: Imperial College London
Year: 2023

description: The linear stability and numerical analysis of geophysical flow patterns is carried out on the beta-plane in a quasigeostrophic approximation. We consider initial steady state dipoles in a one-and-a-half-layer model that are capable of zonal drift in either direction. Despite previous numerical works suggesting that eastward propagating dipoles are stable, our high resolution simulations identify the spontaneous symmetry breaking of weak dipoles over time. The evolution is associated with a growing critical mode with even symmetry about the zonal axis. On carrying out a linear stability analysis, the critical modes obtained share consistency with the numerical fields. In addition, both methods of analysis show that the linear growth rate is inversely proportional to the dipole intensity. Furthermore, the partner separation becomes more pronounced after the linear growth stage, suggesting that nonlinear effects play a pivotal role in the underlying dynamics. Beyond this, the dynamics of initially tilted dipoles and dipole-rider solutions are considered, while stronger dipoles are further analysed using the method of distillation. Flows over sinusoidal bottom relief are considered in a two-layer model on the quasigeostrophic beta-plane. Fourier mode solutions are assumed for the layer-wise perturbation field in order to carry out a linear stability analysis, from which a coupled eigenproblem is derived between fluid columns for both zonal and meridional bottom irregularities. The presence of zonally oriented multiple ridges stabilises an otherwise unstable homogeneous zonal current with respect to increases in the number of ridges and ridge amplitude. Moreover, a bifurcation occurs in the unstable mode spectra and is dependent on the number of ridges. The critical eigenmodes in this case are found to be eddy chains of alternating sign, and these share remarkable resemblance with those obtained numerically. Meridionally oriented multiple ridges are also considered, but are found not to affect the maximum growth rate directly.
A U(1) non-universal anomaly-free model with three Higgs doublets and one singlet scalar field
Creators: name: Mantilla, S. F.
name: Martinez, R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The flavor problem, neutrino physics and the fermion mass hierarchy are important motivations to extend the Standard Model into the TeV scale. A new family non-universal extension is presented with three Higgs doublets, one Higgs singlet and one scalar dark matter candidate. Exotic fermions are included in order to cancel chiral anomalies and to allow family non-universal $\mathrm{U(1)}_{X}$ charges. By implementing an additional $\mathbb{Z}_{2}$ symmetry the Yukawa coupling terms are suited in such a way that the fermion mass hierarchy is obtained without fine-tuning. The neutrino sector include Majorana fermions to implement inverse see-saw mechanism. The effective mass matrix for SM neutrinos is fitted to current neutrino oscillation data to check the consistency of the model with experimental evidence, obtaining that the normal-ordering scheme is preferred over the inverse ones and the values of the neutrino Yukawa coupling constants are shown. Finally, the $h\rightarrow τμ$ lepton-flavor-violation process is addressed with the rotation matrices of the CP-even scalars, left- and right-handed charged leptons, yielding definite regions where the model is consistent with CMS reports of $\mathrm{BR}(h\rightarrow τμ)$. Keywords: Flavor Problem, Neutrino Physics, Extended Scalar Sectors, Beyond Standard Model, Fermion masses, Inverse See-Saw Mechanism, LFV.
description: 18 pages, 3 figures, 4 tables, added references
Categorically closed topological groups
Creators: name: Banakh, Taras
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Topology (math.GN)
subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 22A05, 22A15, 54E15

description: Let $\mathcal C$ be a subcategory of the category of topologized semigroups and their partial continuous homomorphisms. An object $X$ of the category ${\mathcal C}$ is called ${\mathcal C}$-closed if for each morphism $f:X\to Y$ of the category ${\mathcal C}$ the image $f(X)$ is closed in $Y$. In the paper we detect topological groups which are $\mathcal C$-closed for the categories $\mathcal C$ whose objects are Hausdorff topological (semi)groups and whose morphisms are isomorphic topological embeddings, injective continuous homomorphisms, continuous homomorphisms, or partial continuous homomorphisms with closed domain.
description: 26 pages
Discrete functional inequalities on lattice graphs
Creators: name: Gupta, Shubham
Publisher: name: Imperial College London
Year: 2023

description: In this thesis, we study problems at the interface of analysis and discrete mathematics. We discuss analogues of well known Hardy-type inequalities and Rearrangement inequalities on the lattice graphs Z^d, with a particular focus on behaviour of sharp constants and optimizers. In the first half of the thesis, we analyse Hardy inequalities on Z^d, first for d=1 and then for d >= 3. We prove a sharp weighted Hardy inequality on integers with power weights of the form n^\alpha. This is done via two different methods, namely 'super-solution' and 'Fourier method'. We also use Fourier method to prove a weighted Hardy type inequality for higher order operators. After discussing the one dimensional case, we study the Hardy inequality in higher dimensions (d >= 3). In particular, we compute the asymptotic behaviour of the sharp constant in the discrete Hardy inequality, as d \rightarrow \infty. This is done by converting the inequality into a continuous Hardy-type inequality on a torus for functions having zero average. These continuous inequalities are new and interesting in themselves. In the second half, we focus our attention on analogues of Rearrangement inequalities on lattice graphs. We begin by analysing the situation in dimension one. We define various notions of rearrangements and prove the corresponding Polya-Szego inequality. These inequalities are also applied to prove some weighted Hardy inequalities on integers. Finally, we study Rearrangement inequalities (Polya-Szego) on general graphs, with a particular focus on lattice graphs Z^d, for d >=2. We develop a framework to study these inequalities, using which we derive concrete results in dimension two. In particular, these results develop connections between Polya-Szego inequality and various isoperimetric inequalities on graphs.
Nonclassical distance in multimode bosonic systems
Creators: name: Nair, Ranjith
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We revisit the notion of nonclassical distance of states of bosonic quantum systems introduced in [M. Hillery, Phys. Rev. A 35, 725 (1987)] in a general multimode setting. After reviewing its definition, we establish some of its general properties. We obtain new upper and lower bounds on the nonclassical distance in terms of the supremum of the Husimi function of the state. Considering several examples, we elucidate the cases for which our lower bound is tight, which include the multimode number states and a class of multimode N00N states. The latter provide examples of states of definite photon number $n \geq 2$ whose nonclassical distance can be made arbitrarily close to the upper limit of $1$ by increasing the number of modes. We show that the nonclassical distance of the even and odd Schrödinger cat states is bounded away from unity regardless of how macroscopic the superpositions are, and that the nonclassical distance is not necessarily monotonically increasing with respect to macroscopicity.
description: 11 pages, 3 figures; Improved presentation and added references; added material on odd coherent states in Section V.D; approximates published version
Computational modelling of the effect of side chain chemistry on the micro-structure and electrolyte interactions of mixed transport polymers
Creators: name: Siemons, Nicholas
Publisher: name: Imperial College London
Year: 2023

description: As we scale up our use of energy storage facilities to meet the demands of the future, the prob- lems associated with current energy storage technologies will grow to unacceptable levels. In this work I explore how we can develop high performing polymers for use as cathode materials in energy storage devices operating with aqueous electrolytes. Energy storage devices using these materials have the potential for low cost production and safe operation. Through a combination of atomistic simulation methods, this thesis relates aspects of the polymer chemistry to their microstructural properties, and subsequently to their ability to operate successfully as electrodes.