cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Fertilizer Use and Maize Production in Sub-Saharan Africa
Creators: name: Heisey, Paul W.
name: Mwangi, Wilfred
name: Heisey, Paul W.
name: Mwangi, Wilfred
Publisher: name: Unknown
Year: 1996
Subjects: Crop Production/Industries

description: In sub-Saharan Africa, greater use of mineral fertilizers is crucial to increasing food production and slowing the rate of environmental degradation. Regional growth rates in fertilizer consumption have never been particularly high, in part because the real price of fertilizer is higher in Africa than in many other developing regions. As subsidies have been removed and exchange-rate distortions corrected over the past decade or more, relative prices paid by farmers have risen to reflect more closely the economic cost of fertilizer. Consumption growth has thus slowed even more. Nonetheless, during the period of declining growth in consumption, fertilizer use on cereals, particularly maize, has become relatively more important than use on cash crops. Strategies for increasing fertilizer use should thus direct more attention to maize and other important staples. In higher potential areas, some fertilizer use on maize is often economically profitable even at higher relative prices of fertilizer. Additional research on the limiting nutrient under farmers' conditions or on the interactions between nutrients and other crop-management factors could help to increase profitability. Policy analysis for Africa's fertilizer sector has tended to focus on subsidies and to neglect other important issues, such as solving credit problems at many points in the marketing channel, supporting appropriate agricultural research, and developing and maintaining infrastructure. Agricultural sector strategies that give sufficient attention to these issues must be developed. Although subsidy removal must be one ultimate policy objective, we recommend gradual withdrawal in countries where fertilizer consumption levels are relatively high. Because many African governments require time and stability to develop policy capacity, detailed institutional analyses can help design second-best solutions to problems of fertilizer policy.
Star-in-a-box simulations of fully convective stars
Creators: name: Käpylä, Petri J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: (abridged) Context: Main-sequence late-type stars with masses less than $0.35 M_\odot$ are fully convective. Aims: The goal is to study convection, differential rotation, and dynamos as functions of rotation in fully convective stars. Methods: Three-dimensional hydrodynamic and magnetohydrodynamic numerical simulations with a star-in-a-box model, where a spherical star is immersed inside of a Cartesian cube, are used. The model corresponds to a $0.2M_\odot$ M5 dwarf. Rotation periods ($P_{\rm rot}$) between 4.3 and 430 days are explored. Results: The slowly rotating model with $P_{\rm rot}=430$ days produces anti-solar differential rotation with a slow equator and fast poles, along with predominantly axisymmetric quasi-steady large-scale magnetic fields. For intermediate rotation ($P_{\rm rot}=144$ and $43$ days) differential rotation is solar-like (fast equator, slow poles) and large-scale magnetic fields are mostly axisymmetric and either quasi-stationary or cyclic. The latter occurs in a similar parameter regime as in other numerical studies in spherical shells, and the cycle period is similar to observed cycles in fully convective stars with comparable $P_{\rm rot}$. In the rapid rotation regime the differential rotation is weak and the large-scale magnetic fields are increasingly non-axisymmetric with a dominating $m=1$ mode. This large-scale non-axisymmetric field also exhibits azimuthal dynamo waves. Conclusions: The results of the star-in-a-box models agree with simulations of partially convective late-type stars in spherical shells in that the transitions in differential rotation and dynamo regimes occur at similar rotational regimes in terms of the Coriolis (inverse Rossby) number. This similarity between partially and fully convective stars suggests that the processes generating differential rotation and large-scale magnetism are insensitive to the geometry of the star.
description: 17 pages, 11 figures, submitted to Astron. Astrophys, revised as per referee report
Degradation-cost-aware scheduling of electric vehicle charging and discharging
Creators: name: Riebesel, Lea
name: Xhonneux, André
name: Müller, Dirk
Publisher: name: Forschungzentrum Jülich
Year: 2023

description: Advanced Battery Power 2023, Aachen, Germany, 9 Apr 2023 - 11 Apr 2023
description: Degradation-cost-aware scheduling of electric vehicle charging and discharging Lithium-ion battery degradation is strongly dependent on operating conditions. Battery degradation imposes costs on electric vehicle owners. To ensure economically viable participation in vehicle-to-grid schemes, the cost of battery degradation due to battery cycling for this purpose has to be taken into account. Cycle depth is one crucial stress factor for battery operation according to tests. Therefore, an optimization model for a vehicle-to-grid-enabled electric vehicle is presented that schedules charging and discharging while modeling calendar degradation as a function of state of charge. To keep the model computationally tractable, a mixed-integer linear program is formulated. Battery degradation in terms of capacity loss is defined as a piecewise-linear function based on an empirical model. In the model, capacity loss due to calendar aging is dependent on state of charge and capacity loss due to cycle aging is dependent on number of full equivalent cycles. In a case study, we optimize the charging and discharging schedule of a vehicle-to-grid-enabled electric vehicle in a household for the prediction horizon of one day. Energy costs consist of an energy costs and a power costs. The energy cost is based on electricity cost per unit. The power price is based on grid fee costs per unit of the daily peak power use. The schedules aim to minimize both energy costs and battery degradation costs. The study compares state of charge levels for the described degradation-cost-aware model to a reference model without degradation cost model. By comparison to the reference model, the study shows that degradation-cost-aware scheduling is able to reduce the degradation.
A semi Markov model for mammographic detection of breast cancer
Creators: name: Chan, Keith James
Publisher: name: University of British Columbia
Year: 2009

description: Mammography is used as a screening tool to detect breast cancer at an early stage. The process of breast cancer detection using mammography is modelled with a semi-Markov process composed of three states: cancer-free (0), preclinical cancer (1) and clinical cancer (2). It is assumed that screening provides the ability to detect disease while it is still in the preclinical state before it enters the clinical state, however screening measurement is subject to error. The sojourn time in the preclinical detectable phase is thus of particular interest and it plays an important role in the design and assessment of screening programmes. In previous work, the transition rate into the preclinical detectable phase has been modelled by an age-specific step function based on age at first screen. This does not lead to an increasing incidence of breast cancer with age but observations in several populations indicate that incidence increases at approximately the third power of age. This relationship is induced in the model by introducing a smooth age dependent transition rate into the preclinical detectable phase. The model is applied to data provided by The Screening Mammography Programme of British Columbia (SMPBC). A Quasi-Newton algorithm is used to minimize the negative log likelihood function to obtain maximum likelihood estimates of the model parameters. Comparisons will be made with other published results and the effect of various assumptions examined.
Quantum Dot in a Hybrid Structure with Dipolar Excitons
Creators: name: Mahmoodian, M. M.
name: Chaplik, A. V.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Electron states in a quantum dot (QD) located near a 2D system of dipolar excitons are perturbed by fluctuations of the exciton density caused by the electron-exciton interaction. This results in the frequency changes of electron transitions in a QD. The frequency depends on the exciton density, as well as on the exciton gas phase state. In the present work, the shifts of the two lowest QD energy levels are found both in the normal state of the exciton system and for the Bose-Einstein condensation (BEC) regime.
description: 5 pages, 5 figures
Derivatives of random matrix characteristic polynomials with applications to elliptic curves
Creators: name: Snaith, N. C.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Number Theory (math.NT)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: The value distribution of derivatives of characteristic polynomials of matrices from SO(N) is calculated at the point 1, the symmetry point on the unit circle of the eigenvalues of these matrices. We consider subsets of matrices from SO(N) that are constrained to have $n$ eigenvalues equal to 1, and investigate the first non-zero derivative of the characteristic polynomial at that point. The connection between the values of random matrix characteristic polynomials and values of $L$-functions in families has been well-established. The motivation for this work is the expectation that through this connection with $L$-functions derived from families of elliptic curves, and using the Birch and Swinnerton-Dyer conjecture to relate values of the $L$-functions to the rank of elliptic curves, random matrix theory will be useful in probing important questions concerning these ranks.
title: Κατασκευή εκπαιδευτικού μοντέλου εναλλάκτη θερμότητας
title: Construction of an educational model fοr a heat exchanger
Creators: name: Ζαλης Κωνσταντινος
Publisher: name: Technical University of Crete
Year: 2023

description: Στην παρούσα διπλωματική εργασία θα πραγματοποιηθεί ο σχεδιασμός και η κατασκευή ενός εναλλάκτη θερμότητας. Συγκεκριμένα, στην αρχή θα αναλυθεί η βασική θεωρία για την κατανόηση των εναλλακτών θερμότητας. Στη συνέχεια θα γίνει η σχεδίαση μοντέλου περιλαμβάνοντας τα πλήρη μηχανολογικά σχέδια όπου θα αποτελούνται από το συνοπτικό και τα κατασκευαστικά των επιμέρους εξαρτημάτων. Τέλος, ο εναλλάκτης θερμότητας θα κατασκευαστεί σε φυσική κλίμακα μέτρησης και το κάθε στάδιο κατασκευής του θα περιγράφεται αναλυτικά.
High Redshift Supernovae: Cosmological Implications
Creators: name: Panagia, Nino
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We review the findings for the values of the cosmological parameters as derived from high-redshift SNIa measurements. The most recent results confirm the picture of a non-empty inflationary Universe that is consistent with a cosmological constant Omega_Lambda~0.7. This implies that the expansion of the Universe is currently accelerated by the action of some mysterious dark energy. We also discuss the possibility and the consequences of the fact that SNIa may not be "perfect" standard candles, in the sense of having properties in the early Universe that are systematically different from those they have at the present times.
description: [14 pages, 4 figures] Invited review, to be published in the proceedings of the Vulcano Workshop 2004 "Frontier Objects in Astrophysics and Particle Physics", F. Giovannelli & G. Mannocchi (eds.), Italian Physical Society, Editrice Compositori, Bologna, Italy (in press)
Elicitation of questions and answers, vocabulary for modern things
Creators: name: Parker, Verdena
name: Chase, Sara
name: Lee-Wynant, Tyler
name: Spence, Justin
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2020
Subjects: subject: hup

description: Audio file VP-160816-06: elicitation of questions and answers for language learners, also some Hupa terms for phone number, email address, Facebook, texting, etc.
title: On efficiency of earth-abundant chalcogenide photovoltaic materials buffered with CdS: the limiting effect of band alignment
Creators: name: Ghorbani, Elaheh
Publisher: name: IOP Publishing
Year: 2024

description: Earth-abundant and environmentally-friendly Cu₂–II–IV–VI₄ (II = Sr, Ba; IV = Ge, Sn; VI = S,Se) are considered materials for the absorber layers in thin film solar cells. Attempts to understand and improve optoelectronic properties of these newly emerged absorbers resulted in an efficiency of 5.2% in less than two years. However, the energy band alignment at the buffer/absorber interface has not been studied yet; an information which is of crucial importance for designing high performance devices. Therefore, current study focuses on the band offsets between these materials and the CdS buffer. Using first-principles calculations, band discontinuities are calculated at the buffer/absorber interface. The results yield a type-II band alignment between all Cu₂–II–IV–VI₄ absorbers and CdS, hence a negative ΔEc. Adoption of a negative ΔEc (cliff-like conduction band offset) at the buffer/absorber interface, however, gives rise to low open circuit voltage and high interface-related recombinations. Therefore, it is necessary to search for an alternative buffer material that forms a type-I band alignment with these absorbers, where the conduction band minimum and the valence band maximum are both localized on the absorber side.
On the treatment of threshold effects in SUSY spectrum computations
Creators: name: Baer, H.
name: Ferrandis, J.
name: Kraml, S.
name: Porod, W.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We take a critical view of the treatment of threshold effects in SUSY spectrum computations from high-scale input. We discuss the two principal methods of (a) renormalization at a common SUSY scale versus (b) integrating out sparticles at their own mass scales. We point out problems in the implementations in public spectrum codes, together with suggestions for improvements. In concrete examples, we compare results of Isajet7.72 and Spheno2.2.3, and present the improvements done in Isajet7.73. We also comment on theoretical uncertainties. Last but not least, we outline how a consistent multiscale approach may be achieved.
description: 15 pages, 1 figure
The Walker Abel-Jacobi map descends
Creators: name: Achter, Jeff
name: Casalaina-Martin, Sebastian
name: Vial, Charles
Publisher: name: arXiv
Year: 2021
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: For a complex projective manifold, Walker has defined a regular homomorphism lifting Griffiths' Abel-Jacobi map on algebraically trivial cycle classes to a complex abelian variety, which admits a finite homomorphism to the Griffiths intermediate Jacobian. Recently Suzuki gave an alternate, Hodge-theoretic, construction of this Walker Abel-Jacobi map. We provide a third construction based on a general lifting property for surjective regular homomorphisms, and prove that the Walker Abel-Jacobi map descends canonically to any field of definition of the complex projective manifold. In addition, we determine the image of the l-adic Bloch map restricted to algebraically trivial cycle classes in terms of the coniveau filtration.
description: 17 pages
Relative humidity in droplet and airborne transmission of disease
Creators: name: Božič, Anže
name: Kanduč, Matej
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: A large number of infectious diseases is transmitted by respiratory droplets. How long these droplets persist in the air, how far they can travel, and how long the pathogens they might carry survive are all decisive factors for the spread of droplet-borne diseases. The subject is extremely multifaceted and its aspects range across different disciplines, yet most of them have only seldom been considered in the physics community. In this review, we discuss the physical principles that govern the fate of respiratory droplets and any viruses trapped inside them, with a focus on the role of relative humidity. Importantly, low relative humidity -- as encountered, for instance, indoors during winter and inside aircraft -- facilitates evaporation and keeps even initially large droplets suspended in air as aerosol for extended periods of time. What is more, relative humidity affects the stability of viruses in aerosol through several physical mechanisms such as efflorescence and inactivation at the air-water interface, whose role in virus inactivation nonetheless remains poorly understood. Elucidating the role of relative humidity in the droplet spread of disease would permit us to design preventive measures that could aid in reducing the chance of transmission, particularly in indoor environment.
description: 36 pages, 11 figures
Cramer's estimate for a reflected Levy process
Creators: name: Doney, R. A.
name: Maller, R. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60G51, 60G17. (Primary)

description: The natural analogue for a Levy process of Cramer's estimate for a reflected random walk is a statement about the exponential rate of decay of the tail of the characteristic measure of the height of an excursion above the minimum. We establish this estimate for any Levy process with finite negative mean which satisfies Cramer's condition, and give an explicit formula for the limiting constant. Just as in the random walk case, this leads to a Poisson limit theorem for the number of ``high excursions.''
description: Published at http://dx.doi.org/10.1214/105051605000000016 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Real Hypercomputation and Continuity
Creators: name: Ziegler, Martin
Publisher: name: arXiv
Year: 2005
Subjects: subject: Logic in Computer Science (cs.LO)
subject: Computational Complexity (cs.CC)
subject: FOS: Computer and information sciences
subject: F.1.1; F.1.2; F.4.1

description: By the sometimes so-called 'Main Theorem' of Recursive Analysis, every computable real function is necessarily continuous. We wonder whether and which kinds of HYPERcomputation allow for the effective evaluation of also discontinuous f:R->R. More precisely the present work considers the following three super-Turing notions of real function computability: * relativized computation; specifically given oracle access to the Halting Problem 0' or its jump 0''; * encoding real input x and/or output y=f(x) in weaker ways also related to the Arithmetic Hierarchy; * non-deterministic computation. It turns out that any f:R->R computable in the first or second sense is still necessarily continuous whereas the third type of hypercomputation does provide the required power to evaluate for instance the discontinuous sign function.
description: previous version (extended abstract) has appeared in pp.562-571 of "Proc. 1st Conference on Computability in Europe" (CiE'05), Springer LNCS vol.3526
Elicitation of miscellaneous vocabulary
Creators: name: Parker, Verdena
name: Chase, Sara
name: Lee-Wynant, Tyler
name: Spence, Justin
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2020
Subjects: subject: hup

description: Audio file VP-160816-05: brief elicitation of miscellaneous vocabulary (includes plant names and uses, some phrases).
Online sharing and support among users of an MND forum
Creators: name: Ellis, Julie
name: Lovatt, Melanie
name: Bath, Peter
Publisher: name: F1000Research
Year: 2016

description: Background
There are increasing opportunities for individuals with Motor Neurone Disease (MND) and their carers to seek information and share knowledge, experiences and emotions online. Although studies have examined the use of web forums within healthcare and some attention has been paid to information exchange and provision of advice, few studies have focused on the processes of sharing of information and experiences. The role of trust and empathy in mediating illness-based online sharing is also under-researched.

This poster will report work in progress from a research project that is examining information posted to the MND Association online forum. The study is part of a large-scale project entitled 'A Shared Space and a Space for Sharing' which is investigating how people in extreme circumstances share information online and how acts of sharing impact on the development of trust and empathy.

Objectives
This project will investigate the processes (e.g., emotional, practical, relational) involved in sharing in the MND Association forum, and will establish what the potential benefits are, if any, of developing trusting and empathic relationships in online environments for those living with MND.

Findings
The poster will report on initial themes emerging from the analysis.

Outcomes
The findings will provide understanding about how trust and empathy can be facilitated in online environments. They will also highlight factors that contribute to under-sharing, poor sharing and loss of trust between individuals interacting in online spaces. This will be of interest and practical use for charitable and health organisations (including the MND Association) seeking to explore innovative ways of using, designing and facilitating digital environments to deliver and/or enhance support services.

Acknowledgements

Thanks to the MND Association for their support with this work.

This project is part of the 'A Shared Space and a Space for Sharing', funded through the following cross-council programmes:
Partnership for Conflict, Crime and Security Research (lead: Economic and Social Research Council (ESRC)),
Connected Communities (lead: Arts & Humanities Research Council (AHRC)),
Digital Economy (lead: Engineering and Physical Sciences Research Council (EPSRC)) in partnership with:
Defence Science and Technology Laboratory (Dstl),
Centre for the Protection of National Infrastructure (CPNI)
Utilizing relativistic time dilation for time-resolved studies
Creators: name: Daoud, Hazem
name: Miller, R. J. Dwayne
Publisher: name: arXiv
Year: 2020
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Time-resolved studies have so far relied on rapidly triggering a photo-induced dynamic in chemical or biological ions or molecules and subsequently probing them with a beam of fast moving photons or electrons that crosses the studied samples in a short period of time. Hence, the time resolution of the signal is mainly set by the pulse duration of the pump and probe pulses. In this paper we propose a different approach to this problem that has the potential to consistently achieve orders of magnitude higher time resolutions than what is possible with laser technology or electron beam compression methods. Our proposed approach relies on accelerating the sample to a high speed to achieve relativistic time dilation. Probing the time-dilated sample would open up previously inaccessible time resolution domains.
Entropy production in Gaussian thermostats
Creators: name: Dairbekov, N. S.
name: Paternain, G. P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Dynamical Systems (math.DS)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We show that an arbitrary Anosov Gaussian thermostat on a surface is dissipative unless the external field has a global potential.
Inversion of adjunction on log canonicity
Creators: name: Kawakita, Masayuki
Publisher: name: arXiv
Year: 2005
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14E30; 14N30

description: We prove inversion of adjunction on log canonicity.
description: 4 pages; minor typos in the proof of Lemma 3 corrected
Zstress: A zebrafish high throughput phenotypic screen and validation in the Sod1 G93a mouse model
Creators: name: McGown, Alexander
name: Binny, Chris
name: Grierson, Andrew
name: Mead, Richard
name: Shaw, Pamela
name: Tennore Ramesh
Publisher: name: F1000Research
Year: 2016

description: Background: Amyotrophic lateral sclerosis/ Motor Neurone Disease (ALS/MND) is a devastating neurodegenerative disease.  Mutations in the SOD1 gene are one of the major causes of familial ALS.  Sod1 misfolding is also strongly implicated in sporadic ALS; thus drugs that impact sod1 mediated pathogenesis have huge potential in treating ALS.  Phenotypic screens have re-emerged as an important methodology in drug discovery.  Mutant sod1 zebrafish developed in our lab show all the hallmark features of ALS.  By the use of a novel fluorescent reporter of mutant sod1 mediated neuronal stress, we developed a high throughput phenotypic screen and identified a novel neuroprotective compound.

Discussion and conclusions:  Use of mutant sod1 zebrafish model of ALS is amenable for highthroughput drug screening and serves as an excellent platform for bringing lead compounds for testing in pre-clinical mouse models of ALS.
Collective effects in spin-crossover chains with exchange interaction
Creators: name: Timm, Carsten
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The collective properties of spin-crossover chains are studied. Spin-crossover compounds contain ions with a low-spin ground state and low lying high-spin excited states and are of interest for molecular memory applications. Some of them naturally form one-dimensional chains. Elastic interaction and Ising exchange interaction are taken into account. The transfer-matrix approach is used to calculate the partition function, the fraction of ions in the high-spin state, the magnetization, susceptibility, etc., exactly. The high-spin-low-spin degree of freedom leads to collective effects not present in simple spin chains. The ground-state phase diagram is mapped out and compared to the case with Heisenberg exchange interaction. The various phases give rise to characteristic behavior at nonzero temperatures, including sharp crossovers between low- and high-temperature regimes. A Curie-Weiss law for the susceptibility is derived and the paramagnetic Curie temperature is calculated. Possible experiments to determine the exchange coupling are discussed.
description: 9 pages, 13 color figures, published version
Cooperative success in epithelial public goods games
Creators: name: Renton, Jessie
name: Page, Karen M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: FOS: Biological sciences

description: Cancer cells obtain mutations which rely on the production of diffusible growth factors to confer a fitness benefit. These mutations can be considered cooperative, and studied as public goods games within the framework of evolutionary game theory. The population structure, benefit function and update rule all influence the evolutionary success of cooperators. We model the evolution of cooperation in epithelial cells using the Voronoi tessellation model. Unlike traditional evolutionary graph theory, this allows us to implement global updating, for which birth and death events are spatially decoupled. We compare, for a sigmoid benefit function, the conditions for cooperation to be favoured and/or beneficial for well mixed and structured populations. We find that when population structure is combined with global updating, cooperation is more successful than if there were local updating or the population were well-mixed. Interestingly, the qualitative behaviour for the well-mixed population and the Voronoi tessellation model is remarkably similar, but the latter case requires significantly lower incentives to ensure cooperation.
description: 40 Pages, 15 Figures. Accepted version
Entanglement Hamiltonian of Interacting Systems: Local Temperature Approximation and Beyond
Creators: name: Pourjafarabadi, Mahdieh
name: Najafzadeh, Hanieh
name: Vaezi, Mohammad-Sadegh
name: Vaezi, Abolhassan
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Physics (physics.comp-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the second quantization form of the entanglement Hamiltonian (EH) of various subregions for the ground-state of several interacting lattice fermions and spin models. The relation between the EH and the model Hamiltonian itself is an unsolved problem for the ground-state of generic local Hamiltonians. In this letter, we demonstrate that the EH is practically local and its dominant components are related to the terms present in the model Hamiltonian up to a smooth spatially varying temperature even for (a) discrete lattice systems, (b) systems with no emergent conformal or Lorentz symmetry, and (c) for subsystems with non-flat boundaries, up to relatively strong interactions. We show that the mentioned local temperature at a given point decays inversely proportional to its distance from the boundary between the subsystem and the environment. We find the subdominant terms in the EH as well and show that they are severely suppressed away from the boundaries of subsystem and are relatively small near them.
Inhomogeneity induced shortcut to adiabaticity in Ising chains with long-range interactions
Creators: name: Sinha, Aritra
name: Sadhukhan, Debasis
name: Rams, Marek M.
name: Dziarmaga, Jacek
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Driving a homogeneous system across a quantum phase transition in a quench-time $τ_Q$ generates excitations on wavelengths longer than the Kibble-Zurek (KZ) length $\hatξ\proptoτ_Q^{ν/(1+zν)}$ within the KZ time window $\hat t\proptoτ_Q^{zν/(1+zν)}$, where $z$ and $ν$ are the critical exponents. Quenches designed with local time-dependent inhomogeneity can introduce a gap in the spectrum. For a variety of setups with short-range interactions, they have been shown to suppress excitations if the spatial velocity of the inhomogenous front is below the characteristic KZ velocity $\hat v \propto \hatξ/\hat t$. Ising-like models with long-range interactions can have no sonic horizon, spreading information instantaneously across the system. Usually, this should imply that inhomogenous transitions will render the dynamics adiabatic regardless of the front velocity. However, we show that we get an adiabatic transition with no defects only when the inhomogeneous front moves slower than a characteristic crossover velocity $\tilde v \propto θ^{(z-1)ν/(1+ν)}$, where $θ$ is the slope of the inhomogeneous front at the critical point. The existence of this crossover velocity and adiabaticity of the model is a consequence of the energy gap in the quasiparticle spectrum that is opened by the inhomogeneity. This effect can be employed for efficient adiabatic quantum state preparation in systems with long-range interactions.
description: 12 pages, 10 figures (closed to published version)
Molecular Impurities as a Realization of Anyons on the Two-Sphere
Creators: name: Brooks, Morris
name: Lemeshko, Mikhail
name: Lundholm, Douglas
name: Yakaboylu, Enderalp
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Studies on experimental realization of two-dimensional anyons in terms of quasiparticles have been restricted, so far, to only anyons on the plane. It is known, however, that the geometry and topology of space can have significant effects on quantum statistics for particles moving on it. Here, we have undertaken the first step towards realizing the emerging fractional statistics for particles restricted to move on the sphere, instead of on the plane. We show that such a model arises naturally in the context of quantum impurity problems. In particular, we demonstrate a setup in which the lowest-energy spectrum of two linear bosonic/fermionic molecules immersed in a quantum many-particle environment can coincide with the anyonic spectrum on the sphere. This paves the way towards experimental realization of anyons on the sphere using molecular impurities. Furthermore, since a change in the alignment of the molecules corresponds to the exchange of the particles on the sphere, such a realization reveals a novel type of exclusion principle for molecular impurities, which could also be of use as a powerful technique to measure the statistics parameter. Finally, our approach opens up a new numerical route to investigate the spectra of many anyons on the sphere. Accordingly, we present the spectrum of two anyons on the sphere in the presence of a Dirac monopole field.
description: 6 pages, 3 figures with a Supplemental Material
Spectroscopically Confirmed Large-Scale Structures Associated to a z=0.83 Cluster
Creators: name: Tanaka, Masayuki
name: Kodama, Tadayuki
name: Arimoto, Nobuo
name: Tanaka, Ichi
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: (Abridged) We present a discovery of definitive large-scale structures around RXJ0152.7--1352 at z=0.83 based on spectroscopic redshifts. In our previous papers, we reported a photometric identification of the large-scale structures at z~0.8. A spectroscopic follow-up observation was carried out on 8 selected regions covering the most prominent structures to confirm their association to the main cluster. In six out of the eight fields, a well isolated peak is identified in the distribution of spectroscopic redshifts at or near the cluster redshift. This is strong evidence for the presence of large-scale structures associated to the main cluster at z=0.83. We then investigate stellar populations of galaxies in the structures. The composite spectra are constructed from a number of red member galaxies on the colour-magnitude sequence. We consider three representative environments -- cluster, group, and field. The ``cluster'' red galaxies do not show any sign of on-going or recent star formation activities and the passive evolution can naturally link them to the present-day red sequence galaxies in the Sloan Digital Sky Survey. In contrast, the red galaxies in ``groups'' and in the ``field'' tend to show signs of remaining and/or recent star formation activities characterized by weak [OII] emissions and/or strong H delta absorptions. Our current data seem to favour a scenario that star formation is truncated in a short time scale (<1Gyr). This would imply that galaxy-galaxy interactions are responsible for the truncation of star formation.
description: 14 pages, 9 figures, accepted for publication in MNRAS
Modelling excitonic Mott transitions in two-dimensional semiconductors
Creators: name: Kudlis, A.
name: Iorsh, I.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We analyze the many-particle correlations that affect the optical properties of two-dimensional semiconductors. These correlations manifest themselves through the specific optical resonances such as excitons, trions, etc. Starting from the generic electron-hole Hamiltonian and employing the microscopic Heisenberg equation of motion the infinite hierarchy of differential equations can be obtained. In order to decouple the system we address the cluster expansion technique which provides a regular procedure of consistent accounting of many-particle correlation contributions into the interband polarization dynamics. In particular, the partially taken into account three-particle correlations modify the behavior of absorption spectra with the emergence of a trion-like peak additional to excitonic ones. In contrast to many other approaches, the proposed one allows us to model the optical response of 2d semiconductors in the regime when the Fermi energies are of the order of the exciton and trion binding energies, thus allowing us to rigorously model the onset of the excitonic Mott transition, the regime being recently studied in various 2d semiconductors, such as transition metal dichalcogenides.
Inversion of statistics and thermalization in the Unruh effect
Creators: name: Arrechea, Julio
name: Barceló, Carlos
name: Garay, Luis J.
name: García-Moreno, Gerardo
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We derive a master equation for the reduced density matrix of a uniformly accelerating quantum detector in arbitrary dimensions, generically coupled to a field initially in its vacuum state, and analyze its late time regime. We find that such density matrix asymptotically reaches a Gibbs state. The particularities of its evolution towards this state are encoded in the response function, which depends on the dimension, the properties of the fields, and the specific coupling to them. We also compare this situation with the thermalization of a static detector immersed in a thermal field state, pinpointing the differences between both scenarios. In particular, we analyze the role of the response function and its effect on the evolution of the detector towards equilibrium. Furthermore, we explore the consequences of the well-known statistics inversion of the response function of an Unruh-DeWitt detector linearly coupled to a free scalar field in odd spacetime dimensions. This allows us to specify in which sense accelerated detectors in Minkowski vacuum behave as static detectors in a thermal bath and in which sense they do not.
description: 9 pages, no figures; v2: Minor changes introduced in the text to match the published version
Magnetic ground-state of the one-dimensional ferromagnetic chain compounds $M$(NCS)$_2$(thiourea)$_2$; $M$ = Ni, Co
Creators: name: Curley, Samuel P. M.
name: Scatena, Rebecca
name: Williams, Robert C.
name: Goddard, Paul A.
name: Macchi, Piero
name: Hicken, Thomas J.
name: Lancaster, Tom
name: Xiao, Fan
name: Blundell, Stephen J.
name: Zapf, Vivien
name: Eckert, James C.
name: Krenkel, Elizabeth H.
name: Villa, Jacqueline A.
name: Rhodehouse, Melissa L.
name: Manson, Jamie L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The magnetic properties of the two isostructural molecule-based magnets, Ni(NCS)$_{2}$(thiourea)$_{2}$, $S$ = 1, [thiourea = SC(NH$_2$)$_2$] and Co(NCS)$_{2}$(thiourea)$_{2}$, $S$ = 3/2, are characterised using several techniques in order to rationalise their relationship with structural parameters and ascertain magnetic changes caused by substitution of the spin. Zero-field heat capacity and muon-spin relaxation measurements reveal low-temperature long-range ordering in both compounds, in addition to Ising-like ($D < 0$) single-ion anisotropy ($D_{\rm{Co}} \sim$ -100 K, $D_{\rm{Ni}} \sim$ -10 K). Crystal and electronic structure, combined with DC-field magnetometry, affirm highly quasi-one-dimensional behaviour, with ferromagnetic intrachain exchange interactions $J_{\rm{Co}}\approx+4$ K and $J_{\rm{Ni}}\sim+100$ K and weak antiferromagnetic interchain exchange, on the order of $J'$ $\sim-0.1$ K. Electron charge and spin-density mapping reveals through-space exchange as a mechanism to explain the large discrepancy in $J$-values despite, from a structural perspective, the highly similar exchange pathways in both materials. Both species can be compared to the similar compounds $M$Cl$_2$(thiourea)$_4$, $M$ = Ni(II) (DTN) and Co(II) (DTC), where DTN is know to harbour two magnetic field-induced quantum critical points. Direct comparison of DTN and DTC with the compounds studied here shows that substituting the halide Cl$^-$ ion, for the NCS$^-$ ion, results in a dramatic change in both the structural and magnetic properties.
description: Main text: 13 pages - 11 figures, 2 tables. Supplemental information: 6 pages - 2 figures, 6 tables
Optical Manipulation of Domains in Chiral Topological Superconductors
Creators: name: Yu, Tao
name: Claassen, Martin
name: Kennes, Dante M.
name: Sentef, Michael A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Optical control of chirality in chiral superconductors bears potential for future topological quantum computing applications. When a chiral domain is written and erased by a laser spot, the Majorana modes around the domain can be manipulated on ultrafast time scales. Here we study topological superconductors with two chiral order parameters coupled via light fields by a time-dependent real-space Ginzburg-Landau approach. Continuous optical driving, or the application of supercurrent, hybridizes the two chiral order parameters, allowing one to induce and control the superconducting state beyond what is possible in equilibrium. We show that superconductivity can even be enhanced if the mutual coupling between two order parameters is sufficiently strong. Furthermore, we demonstrate that short optical pulses with spot size larger than a critical one can overcome a counteracting diffusion effect and write, erase, or move chiral domains. Surprisingly, these domains are found to be stable, which might enable optically programmable quantum computers in the future.
description: 6 pages, 3 figures; updated version with discussion of substrate/phonon effects
External Enrichment of Minihalos by the First Supernovae
Creators: name: Hicks, William
name: Wells, Azton
name: Norman, Michael L.
name: Wise, John H.
name: Smith, Britton D.
name: O'Shea, Brian W.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Recent high-resolution simulations of early structure formation have shown that externally enriched halos may form some of the first metal enriched stars. This study utilizes a 1 comoving Mpc$^3$ high-resolution simulation to study the enrichment process of metal-enriched halos down to $z=9.3$. Our simulation uniquely tracks the metals ejected from Population III stars, and we use this information to identify the origin of metals within metal-enriched halos. These halos show a wide range of metallicities, but we find that the source of metals for $\gtrsim$ 50\% of metal-enriched halos is supernova explosions of Population III stars occuring outside their virial radii. The results presented here indicate that external enrichment by metal-free stars dominates the enrichment process of halos with virial mass below $10^{6}\,M_\odot$ down to $z=9.3$. Despite the prevalence of external enrichment in low mass halos, Pop II stars forming due to external enrichment are rare because of the small contribution of low-mass halos to the global star formation rate combined with low metallicities towards the center of these halos resulting from metal ejecta from external sources mixing from the outside-in. The enriched stars that do form through this process have absolute metallicities below $10^{-3}\,Z_\odot$. We also find that the fraction of externally enriched halos increases with time, $\sim 90\%$ of halos that are externally enriched have $M_\mathrm{vir} < 10^6\,M_\odot$, and that pair-instability supernovae contribute the most to the enrichment of the IGM as a whole and are thus are the predominant supernova type contributing to the external enrichment of halos.
description: 15 pages, 12 figures, Accepted for publication in ApJ
title: High-order simulation scheme for active particles driven by stress boundary conditions
Creators: name: Deußen, B.
name: Jayaram, A.
name: Kummer, F.
name: Wang, Y.
name: Speck, T.
name: Oberlack, M.
Publisher: name: IOP Publishing
Year: 2024

description: We study the dynamics and interactions of elliptic active particles in a two dimensional solvent. The particles are self-propelled through prescribing a fluid stress at one half of the fluid-particle boundary. The fluid is treated explicitly solving the Stokes equation through a discontinuous Galerkin scheme, which allows to simulate strictly incompressible fluids. We present numerical results for a single particle and give an outlook on how to treat suspensions of interacting active particles.
Autonomous elastic microswimmer
Creators: name: Era, Katsutomo
name: Koyano, Yuki
name: Hosaka, Yuto
name: Yasuda, Kento
name: Kitahata, Hiroyuki
name: Komura, Shigeyuki
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: A model of an autonomous three-sphere microswimmer is proposed by implementing a coupling effect between the two natural lengths of an elastic microswimmer. Such a coupling mechanism is motivated by the previous models for synchronization phenomena in coupled oscillator systems. We numerically show that a microswimmer can acquire a nonzero steady state velocity and a finite phase difference between the oscillations in the natural lengths. These velocity and phase difference are almost independent of the initial phase difference. There is a finite range of the coupling parameter for which a microswimmer can have an autonomous directed motion. The stability of the phase difference is investigated both numerically and analytically in order to determine its bifurcation structure.
Transcription of story about Verdena meeting Otis
Creators: name: Parker, Verdena
name: Chase, Sara
name: Lee-Wynant, Tyler
name: Spence, Justin
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2020
Subjects: subject: hup

description: Audio files VP-160816-04a/c: Transcribing story about how Verdena met Otis, file VP-011011-10, from 6:36.
Pole-skipping and zero temperature
Creators: name: Natsuume, Makoto
name: Okamura, Takashi
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the pole-skipping phenomenon of the scalar retarded Green's function in the rotating BTZ black hole background. In the static case, the pole-skipping points are typically located at negative imaginary Matsubara frequencies $ω=-(2πT)ni$ with appropriate values of complex wave number $q$. But, in a $(1+1)$-dimensional CFT, one can introduce temperatures for left-moving and right-moving sectors independently. As a result, the pole-skipping points $ω$ depend both on left and right temperatures in the rotating background. In the extreme limit, the pole-skipping does not occur in general. But in a special case, the pole-skipping does occur even in the extreme limit, and the pole-skipping points are given by right Matsubara frequencies.
description: 16 pages, ReVTeX4.2; v2: several clarifications, published version