cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Fubini Theorem for pseudo-Riemannian metrics
Creators: name: Bolsinov, Alexey V.
name: Kiosak, Volodymyr
name: Matveev, Vladimir S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Differential Geometry (math.DG)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 53A20, 53B21, 53C22, 53C50, 53D25, 70G45, 70H06, 70H33, 58J60

description: We generalize the following classical result of Fubini for pseudo-Riemannian metrics: if three essentially different metrics on $M^{n\ge 3}$ share the same unparametrized geodesics, and two of them (say, $g$ and $\bar g$) are strictly nonproportional (i.e., the minimal polynomial of $g^{iα} \bar g_{αj}$ coincides with the characteristic polynomial) at least at one point, then they have constant curvature.
GM 2019 - High Renewable Penetration: Grid Stability Challenges and Grid-Forming Advances
Creators: S. Kynev
J. Sneath
S. Williams
Publisher: name: IEEE
Year: 2019

Technical Session
Several large manufacturers offers grid forming converter for renewable energy power converters. The applications of this type of inverter will gain more attentions as the level of penetration renewables increases in the next decades. The role of these inverters will be even more important when the microgrids structure will be dominant in the future power systems.
GM 2019 - Flexible Energy Supply Beyond Conventional Borders
Creators: J. Jaeger
P. Komarnicki
S. Rupp
P. Meyer
S. Henninger
Publisher: name: IEEE
Year: 2019

Technical Session
The session is addressing European developments in the field of flexibilization and digitalization of electrical energy supply as well as their implementation in power systems. The transition from conventional power plants to a high amount of fluctuating renewables challenges the power grid considerably and requires a continuous development of new grid operation methods and technologies. Two approaches to comply with the increasing complexity are flexibilization and digitalization. By means of that, the energy supply can be developed beyond conventional borders keeping future grids stable and economic.
The panel comprises contributions regarding flexibilization and digitalization of power grids as follows:
� Modelling of Electrical Infrastructure � Digital Twin
� Control Center: Dynamic Power System Control
� Digital Substation: Switchgear, Transducer and Communication
� Energy Routing in Power Grid
� High Flexible Power Hub Control
� Modularisation of Energy Supply with Energy Packets
The Schubert calculus
Creators: name: Higham, David Paul
Publisher: name: University of British Columbia
Year: 2010

description: An enumerative problem asks the following type of question; how many figures (lines, planes, conies, cubics, etc.) meet transversely (or are tangent to) a certain number of other figures in general position? The last century saw the development of a calculus for solving this problem and a large number of examples were worked out by Schubert, after whom the calculus is named. The calculus, however, was not rigorously justified, most especially its main principle whose modern interpretation is that when conditions of an enumerative problem are varied continuously then the number of solutions in the general case is the same as the number of solutions in the special case counted with multiplicities. Schubert called it the principle of conservation of number. To date the principle has been validated in the case where the figures are linear spaces in complex projective space, but only isolated cases have been solved where the figures are curved. Hilbert considered the Schubert calculus of sufficient importance to request its justification in his fifteenth problem. We trace the first foundation of the calculus due primarily to Lefschetz, van der Waerden and Ehresmann. The introduction is historical, being a summary of Kleiman's expository article on Hilbert's fifteenth problem. We describe the Grassmannian and its Schubert subvarieties more formally and describe explicitly the homology of the Grassmannian which gives a foundation for the calculus in terms of algebraic cycles. Finally we compute two examples and briefly mention some more recent developments.
Effective exchange interaction for terahertz spin waves in iron layers
Creators: name: Brandt, Liane
name: Ritzmann, Ulrike
name: Liebing, Niklas
name: Ribow, Mirko
name: Razdolski, Ilya
name: Brouwer, Piet
name: Melnikov, Alexey
name: Woltersdorf, Georg
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The exchange stiffness is a central material parameter of all ferromagnetic materials. Its value controls the Curie temperature as well as the dynamic properties of spin waves to a large extend. Using ultrashort spin current pulses we excite perpendicular standing spin waves (PSSW) in ultrathin epitaxial iron layers at frequencies of up to 2.4 THz. Our analysis shows that for the PSSWs the observed exchange stiffness of iron is about 20% smaller compared to the established iron bulk value. In addition, we find an interface-related reduction of the effective exchange stiffness for layers with the thickness below 10 nm. To understand and discuss the possible mechanisms of the exchange stiffness reduction we develop an analytical 1D-model. In doing so we find that the interface induced reduction of the exchange stiffness is mode-dependent.
Topological Field Theories induced by twisted R-Poisson structure in any dimension
Creators: name: Chatzistavrakidis, Athanasios
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We construct a class of topological field theories with Wess-Zumino term in spacetime dimensions $\ge 2$ whose target space has a geometrical structure that suitably generalizes Poisson or twisted Poisson manifolds. Assuming a field content comprising a set of scalar fields accompanied by gauge fields of degree $(1,p-1,p)$ we determine a generic Wess-Zumino topological field theory in $p+1$ dimensions with background data consisting of a Poisson 2-vector, a $(p+1)$-vector $R$ and a $(p+2)$-form $H$ satisfying a specific geometrical condition that defines a $H$-twisted $R$-Poisson structure of order $p+1$. For this class of theories we demonstrate how a target space covariant formulation can be found by means of an auxiliary connection without torsion. Furthermore, we study admissible deformations of the generic class in special spacetime dimensions and find that they exist in dimensions 2, 3 and 4. The two-dimensional deformed field theory includes the twisted Poisson sigma model, whereas in three dimensions we find a more general structure that we call bi-twisted $R$-Poisson. This extends the twisted $R$-Poisson structure of order 3 by a non-closed 3-form and gives rise to a topological field theory whose covariant formulation requires a connection with torsion and includes a twisted Poisson sigma model in three dimensions as a special case. The relation of the corresponding structures to differential graded Q-manifolds based on the degree shifted cotangent bundle $T^{\ast}[p]T^{\ast}[1]M$ is discussed, as well as the obstruction to them being QP-manifolds due to the Wess-Zumino term.
description: 40 pages
Cyber Security in Cloud: Risk Assessment Models
Creators: name: Bendicho, Carlos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences
subject: C.2.0; C.2.1; C.2.3; C.2.6; C.2.m

description: The present paper shows a proposal of the characteristics Cloud Risk Assessment Models should have and presents the review of the literature considering those characteristics in order to identify current gaps. This work shows a ranking of Cloud RA models and their degree of compliance with the theoretical reference Cloud Risk Assessment model. The review of literature shows that RA approaches leveraging CSA (Cloud Security Alliance) STAR Registry that have into account organizations security requirements present higher degree of compliance, but they still lack risk economic quantification. The myriad of conceptual models, methodologies and frameworks although based on current NIST SP 800:30, ISO 27001, ISO 27005, ISO 30001, ENISA standards could be enhanced by the use of techno-economic models like UTEM, created by the author, in order to conceive more simplified models for effective Risk Assessment and Mitigation closer to the theoretical reference model for Cloud Risk Assessment, available for all cloud models (IaaS, PaaS, SaaS) and easy to use for all stakeholders.
description: 12 pages, 5 figures, 2 tables
Testing Group Fairness via Optimal Transport Projections
Creators: name: Si, Nian
name: Murthy, Karthyek
name: Blanchet, Jose
name: Nguyen, Viet Anh
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (stat.ML)
subject: Computers and Society (cs.CY)
subject: Machine Learning (cs.LG)
subject: Statistics Theory (math.ST)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: We present a statistical testing framework to detect if a given machine learning classifier fails to satisfy a wide range of group fairness notions. The proposed test is a flexible, interpretable, and statistically rigorous tool for auditing whether exhibited biases are intrinsic to the algorithm or due to the randomness in the data. The statistical challenges, which may arise from multiple impact criteria that define group fairness and which are discontinuous on model parameters, are conveniently tackled by projecting the empirical measure onto the set of group-fair probability models using optimal transport. This statistic is efficiently computed using linear programming and its asymptotic distribution is explicitly obtained. The proposed framework can also be used to test for testing composite fairness hypotheses and fairness with multiple sensitive attributes. The optimal transport testing formulation improves interpretability by characterizing the minimal covariate perturbations that eliminate the bias observed in the audit.
Developing system of wireless sensor network and unmaned aerial vehicle for agriculture inspection
Creators: name: Son, Nguyen Truong
name: Hoang, Quach Cong
name: Giang, Dang Thi Huong
name: Trung, Vu Minh
name: Huy, Vuong Quang
name: Tuan, Mai Anh
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: Agricultural production using high technology is an inevitable trend in Vietnam. Especially for material crops which typically need large growing areas, wireless sensor networks has been clearly playing a significant role in increasing productivity, monitoring pests and diseases, mitigating the impact of climate change, and reducing the direct labor of cultivators. This paper constructs an experimental model of agricultural crop field monitoring using a combination of LoRa wireless sensor networks and unmanned aerial vehicles to collect data on conditions of weather and soil, plant health, which helps growers easily making right decisions on solutions for irrigation, pest treatment, and fertilization with the currently planted crops. The system has been developed and experimentized in the field to evaluate some basic features and justified the stability and reliability of the obtained data.
description: in Vietnamese language. https://tapchikhcn.haui.edu.vn/media/30/uffile-upload-no-title30450.pdf
Topology-Level Reactivity in Distributed Reactive Programs: Reactive Acquaintance Management using Flocks
Creators: name: Vonder, Sam Van den
name: Renaux, Thierry
name: De Meuter, Wolfgang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Programming Languages (cs.PL)
subject: FOS: Computer and information sciences

description: Reactive programming is a popular paradigm to program event-driven applications, and it is often proposed as a paradigm to write distributed applications. One such type of application is *prosumer* applications, which are distributed applications that both produce and consume many events. We analyse the problems that occur when using a reactive programming language or framework to implement prosumer applications. We find that the assumption of an open network, which means prosumers of various types spontaneously join and leave the network, can cause a lot of code complexity or run-time inefficiency. At the basis of these issues lies *acquaintance management*: the ability to discover prosumers as they join and leave the network, and correctly maintaining this state throughout the reactive program. Most existing reactive programming languages and frameworks have limited support for managing acquaintances, resulting in accidental complexity of the code or inefficient computations. In this paper we present acquaintance management for reactive programs. First, we design an *acquaintance discovery* mechanism to create a *flock* that automatically discovers prosumers on the network. An important aspect of flocks is their integration with reactive programs, such that a reactive program can correctly and efficiently maintain its state. To this end we design an *acquaintance maintenance* mechanism: a new type of operator for functional reactive programming languages that we call `deploy-*`. The `deploy-*` operator enables correct and efficient reactions to time-varying collections of discovered prosumers. The proposed mechanisms are implemented in a reactive programming language called Stella, which serves as a linguistic vehicle to demonstrate the ideas of our approach. Our implementation of acquaintance management results in computationally efficient and idiomatic reactive code. We evaluate our approach quantitatively via benchmarks that show that our implementation is efficient: computations will efficiently update whenever a new prosumer is discovered, or a connected prosumer is dropped. To evaluate the distributed capabilities of our prototype implementation, we implement a use-case that simulates the bike-sharing infrastructure of Brussels, and we run it on a Raspberry Pi cluster computer. We consider our work to be an important step to use functional reactive programming to build distributed systems for open networks, in other words, distributed reactive programs that involve many prosumer devices and sensors that spontaneously join and leave the network.
GM 2019 - Interactions Between Transmission System Connected Converters
Creators: L. Xuan
M. Quester
T. Schyvens
F. Ceja-Gomez
H. Suriyaarachchi
A. Bayo Salas
R. Renner
D. Jovcic
Publisher: name: IEEE
Year: 2019

Technical Session
Power electronic converters are complex components interacting with the connected system through advanced control loops. With increasing participation of such converters to the energy supply, new problems are seen in practical energy systems, requiring advances in system modeling, problem identification and mitigation. This set of presentations will focus on practical systems and problems/solutions encountered in real systems.
An operator equality involving a continuous field of operators and its norm inequalities
Creators: name: Moslehian, Mohammad Sal
name: Zhang, Fuzhen
Publisher: name: arXiv
Year: 2008
Subjects: subject: Operator Algebras (math.OA)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 47A62 (Primary), 46C15, 47A30, 15A24 (Secondary)

description: Let ${\mathfrak A}$ be a $C^*$-algebra, $T$ be a locally compact Hausdorff space equipped with a probability measure $P$ and let $(A_t)_{t\in T}$ be a continuous field of operators in ${\mathfrak A}$ such that the function $t \mapsto A_t$ is norm continuous on $T$ and the function $t \mapsto \|A_t\|$ is integrable. Then the following equality including Bouchner integrals holds \begin{eqnarray}\label{oi} \int_T|A_t - \int_TA_s{\rm d}P|^2 {\rm d}P=\int_T|A_t|^2{\rm d}P - |\int_TA_t{\rm d}P|^2 . \end{eqnarray} This equality is related both to the notion of variance in statistics and to a characterization of inner product spaces. With this operator equality, we present some uniform norm and Schatten $p$-norm inequalities.
description: 10 pages, to appear in Linear Algebra and its Applications
Kondo effects in a C_60 single-molecule transistor
Creators: name: Roch, N.
name: Winkelmann, C. B.
name: Florens, S.
name: Bouchiat, V.
name: Wernsdorfer, W.
name: Balestro, F.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We have used the electromigration technique to fabricate a $\rm{C_{60}}$ single-molecule transistor (SMT). We present a full experimental study as a function of temperature, down to 35 mK, and as a function of magnetic field up to 8 T in a SMT with odd number of electrons, where the usual spin-1/2 Kondo effect occurs, with good agreement with theory. In the case of even number of electrons, a low temperature magneto-transport study is provided, which demonstrates a Zeeman splitting of the zero-bias anomaly at energies well below the Kondo scale.
description: 4 pages, 3 figures
Backreaction from non-conformal quantum fields in de Sitter spacetime
Creators: name: Pérez-Nadal, Guillem
name: Roura, Albert
name: Verdaguer, Enric
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the backreaction on the mean field geometry due to a non-conformal quantum field in a Robertson-Walker background. In the regime of small mass and small deviation from conformal coupling, we compute perturbatively the expectation value of the stress tensor of the field for a variety of vacuum states, and use it to obtain explicitly the semiclassical gravity solutions for isotropic perturbations around de Sitter spacetime, which is found to be stable. Our results show clearly the crucial role of the non-local terms that appear in the effective action: they cancel the contribution from local terms proportional to the logarithm of the scale factor which would otherwise become dominant at late times and prevent the existence of a stable self-consistent de Sitter solution. Finally, the opposite regime of a strongly non-conformal field with a large mass is also considered.
description: 31 pages
Suppressing coherence effects in quantum-measurement based engines
Creators: name: Lin, Zhiyuan
name: Su, Shanhe
name: Chen, Jingyi
name: Chen, Jincan
name: Santos, Jonas F. G.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The recent advances in the study of thermodynamics of microscopic processes have driven the search for new developments in energy converters utilizing quantum effects. We here propose a universal framework to describe the thermodynamics of a quantum engine fueled by quantum projective measurements. Standard quantum thermal machines operating in a finite-time regime with a driven Hamiltonian that does not commute in different times have the performance decreased by the presence of coherence, which is associated with a larger entropy production and irreversibility degree. However, we show that replacing the standard hot thermal reservoir by a projective measurement operation with general basis in the Bloch sphere and controlling the basis angles suitably could improve the performance of the quantum engine as well as decrease the entropy change during the measurement process. Our results go in direction of a generalization of quantum thermal machine models where the fuel comes from general sources beyond the standard thermal reservoir.
Atom as a "Dressed" Nucleus
Creators: name: Kalitvianski, Vladimir
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: It is shown that the electrostatic potential of atomic nucleus "seen" by a fast charged projectile at short distances is smeared quantum mechanically due to nucleus motion around the atomic center of inertia. For example, the "positive charge cloud" size in the Hydrogen ground state is much larger than the proper proton size. It is even bigger for the target atoms in excited initial states. The elastic scattering at large angles is generally weaker than the Rutherford one since the effective potential at short distances is softer than the Colombian one due to a natural "cutoff". In addition, the large angle scattering leads to the target atom excitations due to pushing the nucleus (=> inelastic processes). The Rutherford cross section is in fact the inclusive rather than the elastic one. These results are analogous to the QED ones. The difference and the value of presented below non relativistic atomic calculations is in non perturbatively (exact) nucleus "dressing" that immediately leads to correct physical results and to significant technical simplifications. In these respects the nucleus bound in an atom is a simple but a rather realistic model of a "dressed" charge in the QFT. This idea is briefly demonstrated on the real electron model (electronium) that is made free from infinities.
description: 16 pages, 4 figures, original study results, corrected typos, improved text, revised chapter on electronium, minor improvements
Building an Ensemble of Classifiers via Randomized Models of Ensemble Members
Creators: name: Trajdos, Pawel
name: Kurzynski, Marek
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Many dynamic ensemble selection (DES) methods are known in the literature. A previously-developed by the authors, method consists in building a randomized classifier which is treated as a model of the base classifier. The model is equivalent to the base classifier in a certain probabilistic sense. Next, the probability of correct classification of randomized classifier is taken as the competence of the evaluated classifier. In this paper, a novel randomized model of base classifier is developed. In the proposed method, the random operation of the model results from a random selection of the learning set from the family of learning sets of a fixed size. The paper presents the mathematical foundations of this approach and shows how, for a practical application when learning and validation sets are given, one can determine the measure of competence and build a MC system with the DES scheme. The DES scheme with the proposed model of competence was experimentally evaluated on the collection of 67 benchmark datasets and compared in terms of eight quality criteria with two ensemble classifiers which use the previously-proposed concepts of randomized model. The proposed approach achieved the lowest ranks for almost all investigated quality criteria.
United Monoids: Finding Simplicial Sets and Labelled Algebraic Graphs in Trees
Creators: name: Mokhov, Andrey
Publisher: name: arXiv
Year: 2022
Subjects: subject: Programming Languages (cs.PL)
subject: FOS: Computer and information sciences

description: Graphs and various graph-like combinatorial structures, such as preorders and hypergraphs, are ubiquitous in programming. This paper focuses on representing graphs in a purely functional programming language like Haskell. There are several existing approaches; one of the most recently developed ones is the "algebraic graphs" approach (2017). It uses an algebraic data type to represent graphs and has attracted users, including from industry, due to its emphasis on equational reasoning and making a common class of bugs impossible by eliminating internal invariants. The previous formulation of algebraic graphs did not support edge labels, which was a serious practical limitation. In this paper, we redesign the main algebraic data type and remove this limitation. We follow a fairly standard approach of parameterising a data structure with a semiring of edge labels. The new formulation is both more general and simpler: the two operations for composing graphs used in the previous work can now be obtained from a single operation by fixing the semiring parameter to zero and one, respectively. By instantiating the new data type with different semirings, and working out laws for interpreting the resulting expression trees, we discover an unusual algebraic structure, which we call "united monoids", that is, a pair of monoids whose unit elements coincide. We believe that it is worth studying united monoids in their full generality, going beyond the graphs which prompted their discovery. To that end, we characterise united monoids with a minimal set of axioms, prove a few basic theorems, and discuss several notable examples. We validate the presented approach by implementing it in the open-source *algebraic-graphs* library. Our theoretical contributions are supported by proofs that are included in the paper and have also been machine-checked in Agda. By extending algebraic graphs with support for edge labels, we make them suitable for a much larger class of possible applications. By studying united monoids, we provide a theoretical foundation for further research in this area.
The structure of molecular clouds and the universality of the clump mass function
Creators: name: Smith, Rowan J.
name: Clark, Paul C.
name: Bonnell, Ian A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Using an SPH simulation of a star-forming region in a molecular cloud, we show that the emergence of a clump mass function (CMF) resembling the stellar initial mass function (IMF) is a ubiquitous feature of molecular cloud structure, but caution against its over-interpretation. We employ three different techniques to extract the clumps in this study. In the first two, we interpolate the SPH particle data to 2 and 3 dimensional grids before performing the clump-find, using position-position (PP) and position-position-velocity (PPV) information respectively. In the last technique, the clump-finding is performed on the SPH data directly, making use of the full 3 dimensional position information. Although the CMF is typically similar to that observed in regions of nearby star formation, the individual clumps and their masses are found to be unreliable since they depend strongly on the parameters and the method of the clump-finding. In particular we find that the resolution and orientation of the data make a significant difference to the resulting properties of the identified clumps in the PP and PPV cases. We conclude that making comparisons between a CMF and the stellar IMF should be done with caution, since the definition of a clump boundary, and hence the number of clumps and their properties, are arbitrary in the extraction method. This is especially true if molecular clouds are truly scale free.
description: 11 pages, 10 figures, accepted for publication in MNRAS
VerSaChI: Finding Statistically Significant Subgraph Matches using Chebyshev's Inequality
Creators: name: Agarwal, Shubhangi
name: Dutta, Sourav
name: Bhattacharya, Arnab
Publisher: name: arXiv
Year: 2021
Subjects: subject: Databases (cs.DB)
subject: FOS: Computer and information sciences

description: Approximate subgraph matching, which is an important primitive for many applications like question answering, community detection, and motif discovery, often involves large labeled graphs such as knowledge graphs, social networks, and protein sequences. Effective methods for extracting matching subgraphs, in terms of label and structural similarities to a query, should depict accuracy, computational efficiency, and robustness to noise. In this paper, we propose VerSaChI for finding the top-k most similar subgraphs based on 2-hop label and structural overlap similarity with the query. The similarity is characterized using Chebyshev's inequality to compute the chi-square statistical significance for measuring the degree of matching of the subgraphs. Experiments on real-life graph datasets showcase significant improvements in terms of accuracy compared to state-of-the-art methods, as well as robustness to noise.
Plasma Properties, Switchback Patches and Low $α$-Particle Abundance in Slow Alfvénic Coronal Hole Wind at 0.13 au
Creators: name: Woolley, Thomas
name: Matteini, Lorenzo
name: McManus, Michael D.
name: Berčič, Laura
name: Badman, Samuel T.
name: Woodham, Lloyd D.
name: Horbury, Timothy S.
name: Bale, Stuart D.
name: Laker, Ronan
name: Stawarz, Julia E.
name: Larson, Davin E.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The Parker Solar Probe (PSP) mission presents a unique opportunity to study the near-Sun solar wind closer than any previous spacecraft. During its fourth and fifth solar encounters, PSP had the same orbital trajectory, meaning that solar wind was measured at the same latitudes and radial distances. We identify two streams measured at the same heliocentric distance ($\sim$0.13au) and latitude ($\sim$-3.5$^{\circ}$) across these encounters to reduce spatial evolution effects. By comparing the plasma of each stream, we confirm that they are not dominated by variable transient events, despite PSP's proximity to the heliospheric current sheet. Both streams are consistent with a previous slow Alfvénic solar wind study once radial effects are considered, and appear to originate at the Southern polar coronal hole boundary. We also show that the switchback properties are not distinctly different between these two streams. Low $α$-particle abundance ($\sim$ 0.6 %) is observed in the encounter 5 stream, suggesting that some physical mechanism must act on coronal hole boundary wind to cause $α$-particle depletion. Possible explanations for our observations are discussed, but it remains unclear whether the depletion occurs during the release or the acceleration of the wind. Using a flux tube argument, we note that an $α$-particle abundance of $\sim$ 0.6 % in this low velocity wind could correspond to an abundance of $\sim$ 0.9 % at 1 au. Finally, as the two streams roughly correspond to the spatial extent of a switchback patch, we suggest that patches are distinct features of coronal hole wind.
description: 9 pages, 5 figures
GM 2019 - Thinking Outside the “Black Box” — Analytical Foundations of Power System Research
Creators: F. Milano
I. Hiskens
D. Hill
Publisher: name: IEEE
Year: 2019

Technical Session
The session will analyze the differences (and interactions) between "black box" approaches to power system research, whereby researchers apply standard software tools (such as e.g. time-domain simulation packages) without much thinking, and rigorous mathematics-based analytical approaches. Both simulation and mathematical analysis draw conclusions based on a mathematical representation of a power system, however the latter focuses on inferring structural properties through derivation of rigorous mathematical results whereas simulation makes quantitative predictions based on specific situations (with simulations usually modelling in greater detail). One of the most exciting developments in power systems analysis in the last ten years has been the revival of engagement by researchers from the optimization and control communities, who naturally take the analytical point of view, along with continued advances by members of the existing power systems community with similar philosophies. The presentations will be from established experts who will illustrate benefits of the analytical approach and also of simulation.
Evolutionary game dynamics in phenotype space
Creators: name: Antal, Tibor
name: Ohtsuki, Hisashi
name: Wakeley, John
name: Taylor, Peter D.
name: Nowak, Martin A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: FOS: Biological sciences

description: Evolutionary dynamics can be studied in well-mixed or structured populations. Population structure typically arises from the heterogeneous distribution of individuals in physical space or on social networks. Here we introduce a new type of space to evolutionary game dynamics: phenotype space. The population is well-mixed in the sense that everyone is equally likely to interact with everyone else, but the behavioral strategies depend on distance in phenotype space. Individuals might behave differently towards those who look similar or dissimilar. Individuals mutate to nearby phenotypes. We study the `phenotypic space walk' of populations. We present analytic calculations that bring together ideas from coalescence theory and evolutionary game dynamics. As a particular example, we investigate the evolution of cooperation in phenotype space. We obtain a precise condition for natural selection to favor cooperators over defectors: for a one-dimensional phenotype space and large population size the critical benefit-to-cost ratio is given by b/c=1+2/sqrt{3}. We derive the fundamental condition for any evolutionary game and explore higher dimensional phenotype spaces.
description: version 2: minor changes; equivalent to final published version
GM 2019 - Variable and Distributed Energy Integration and Provision: Part 2 – Bulk Power System Planning
Creators: D. Lew
H. Mackenzie
Publisher: name: IEEE
Year: 2019

Technical Session
Ensuring sufficient operational flexibility is a necessary part of planning in systems with high penetrations of variable generation. This and the previous panel are two parts of a joint effort between three groups to bring together experiences and insights from operations and planning in systems tackling the flexibility issue in two linked panels. This panel, focused on planning, will cover topics including: the role of flexible generation; accessing flexibility through transmission; flexibility from energy storage, EVs and demand management. The session will draw on experience from around the world in real world and academic settings, and will conclude with a panel discussion with presenters from the panel.
Restricted uniform rational approximations
Creators: name: Borwein, Peter B.
Publisher: name: University of British Columbia
Year: 2010

description: We consider the approximation of continuous functions from various restricted classes of rational functions. More precisely, for a function f continuous on [0,1] we consider [Mathematical Equation] where || || [0,1] is the uniform norm on [0,1] and A[sub n] is some restricted subset of the real rational functions of degree n . We are primarily concerned with the following three restrictions: monotone denominators, denominators having positive coefficients and both numerators and denominators having positive coefficients. We compare the order of approximation (the asymptotic behaviour of ε[sub n] ) from restricted rationals to the orders of approximation by polynomials and unrestricted rationals. We show, for functions that are exactly k-times differentiable on [0,1], that restricted rational approximation cannot be spectacularly more efficient than polynomial approximation. For example, if A[sub n] is the class of rational functions of degree n with monotone denominators and for some f the corresponding [Mathematical Equation] then f is k-times continuously differentiable on (0,1] . The situation is more complicated for analytic functions. In this case restricted rational approximations vary from being no more efficient than polynomials to being arbitrarily faster. For functions of the form ∑a[sub n]x[sup n], where a[sub n] ↓ 0, we show that the order of approximation by rationals with denominators having positive coefficients is the same as the polynomial order. Finally, we develop approximation theorems for rational functions with positive coefficients. (This class does not contain the polynomials so we cannot a priori assert denseness.) We show that it is possible to approximate positive functions fairly efficiently from this class. For instance, if f is analytic and positive on [0,1] then the order of approximation by rational functions of degree n with positive coefficients is at least as rapid as [Mathematical Equation], where ρ > 1 .
A theoretical model of Surtseyan bomb fragmentation
Creators: name: Greenbank, Emma
name: McGuinness, Mark J.
name: Schipper, C. Ian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: Surtseyan eruptions are an important class of mostly basaltic volcanic eruptions first identified in the 1960s, where erupting magma at an air-water interface interacts with large quantities of slurry, a mixture of previously ejected tephra that re-enters the crater together with water. During a Surtseyan eruption, hot magma bombs are ejected that initially contain pockets of slurry. Despite the formation of steam and anticipated subsequent high pressures inside these bombs, many survive to land without exploding. We seek to explain this by building and solving a simplified spherical mathematical model that describes the coupled evolution of pressure and temperature due to the flashing of liquid to vapour within a Surtseyan bomb while it is in flight. Analysis of the model provides a criterion for fragmentation of the bomb due to steam pressure buildup, and predicts that if diffusive steam flow through the porous bomb is sufficiently rapid, the bomb will survive the flight intact. This criterion explicitly relates fragmentation to bomb properties, and describes how a Surtseyan bomb can survive in flight despite containing flashing liquid water, contributing to an ongoing discussion in volcanology about the origins of the inclusions found inside bombs.
description: 22 pages, 7 figures. Accepted Proc Roy Soc Lond A, Aug 2021
GM 2019 - Improving Grid Resilience Using HVDC
Creators: N. Kirby
A. Valdes
K. Walker
D. Kell
Publisher: name: IEEE
Year: 2019

Technical Session
This panel will review positive and negative impacts of HVDC transmission on system resilience including cybersecurity issues related to SCADA, WAMPAC (wide area measurement protection and control), power systems controls, operator errors due to lack of situational awareness, misconfiguration or other settings errors. Potential vulnerabilities that HVDC and FACTS systems inherit from the bulk power system through SCADA and other communication systems will be reviewed with an emphasis on how communications for HVDC protection and control differ from those for conventional ac systems. HVDC and FACTS systems also have the ability to improve the resilience of the bulk power system. LCC systems, VSC based systems, and multiterminal DC grids will be compared in terms of their abilities to impact system resilience. Potential detection and mitigation ideas will be presented.
Breakdown of the Hund's Rule in CuFeAs
Creators: name: Song, Ze-Yi
name: Jiang, Xiu-Cai
name: Ouyang, Xiao-Fang
name: Zhang, Yu-Zhong
Publisher: name: arXiv
Year: 2021
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The ground-state properties of CuFeAs were investigated by applying density functional theory calculations within generalized gradient approximation (GGA) and GGA+U. We find that the bicollinear antiferromagnetic state with antiparallel orbital magnetic moments on each iron which violates the Hund's rule is favored by the on-site Coulomb interaction, which is further stabilized by Cu vacancy. The magnetic ground state can be used to understand weak antiferromagnetism in CuFeAs observed experimentally. We argue that breakdown of the Hund's rule may be the possible origin for reduced magnetism in iron pnictides, rather than magnetic fluctuations induced by electronic correlations.
description: 8 pages, 5 figures
EMOTION BIAS AND GENDER
Creators: name: Motoyoshi, Rachel
Publisher: name: Zenodo
Year: 2021
Subjects: natural resting face
emotional valence
gender
female
neutral
positive

description: The pop culture phenomenon of resting bitch face has been discussed frequently through anecdotal and observational evidence. However, it has not been formally studied as a perceptual bias. In this study, we hypothesized that gender would affect perception of emotion and that participants would rate women’s neutral resting faces more negatively than men’s neutral resting faces. To test this hypothesis, we analyzed data from 90 participants who completed an online survey containing 156 trials of face stimuli. These faces included happiness, disgust, and neutral facial emotions. The data collected in this study revealed that the main effects of the variables sex of face and emotion were significant. The interaction between sex of face and emotion was also statistically significant. Planned contrasts revealed that women’s neutral resting faces were rated more negatively than men’s neutral resting faces, women’s disgust faces were also rated more negatively than men’s disgust faces, and female happy expressions were judged as slightly more positive than male’s happy expressions. We also found an effect of gender of the participants for the disgust emotion, as women rated the emotion of disgust more negative compared to men. Therefore, we conclude that there is a significant difference between how expressions of emotion are rated based on gender, and the gender of the participant may also have small effect on perception. Thus, the pop culture phenomenon of resting bitch face can be defined as a perceptual bias related to gender, and there are other gender-based biases that should be studied more extensively. Understanding perceptual biases are key to creating awareness of how implicit judgements impact daily behavior and treatment of specific populations.
Cognition in context: Evidence on affordances and verbal language
Creators: name: Flumini, Andrea <1978>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: M-PSI/01 Psicologia generale

description: This thesis investigated affordances and verbal language to demonstrate the flexibility of embodied simulation processes. Starting from the assumption that both object/action understanding and language comprehension are tied to the context in which they take place, six studies clarified the factors that modulate simulation. The studies in chapter 4 and 5 investigated affordance activation in complex scenes, revealing the strong influence of the visual context, which included either objects and actions, on compatibility effects. The study in chapter 6 compared the simulation triggered by visual objects and objects names, showing differences depending on the kind of materials processed. The study in chapter 7 tested the predictions of the WAT theory, confirming that the different contexts in which words are acquired lead to the difference typically observed in the literature between concrete and abstract words. The study in chapter 8 on the grounding of abstract concepts tested the mapping of temporal contents on the spatial frame of reference of the mental timeline, showing that metaphoric congruency effects are not automatic, but flexibly mediated by the context determined by the goals of different tasks. The study in chapter 9 investigated the role of iconicity in verbal language, showing sound-to-shape correspondences when every-day object figures, result that validated the reality of sound-symbolism in ecological contexts. On the whole, this evidence favors embodied views of cognition, and supports the hypothesis of a high flexibility of simulation processes. The reported conceptual effects confirm that the context plays a crucial role in affordances emergence, metaphoric mappings activation and language grounding. In conclusion, this thesis highlights that in an embodied perspective cognition is necessarily situated and anchored to a specific context, as it is sustained by the existence of a specific body immersed in a specific environment.
Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED
Creators: name: Werlang, T.
name: Guzman, R.
name: Prado, F. O.
name: Villas-Boas, C. J.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a way to engineer an effective anti-Jaynes-Cumming and a Jaynes-Cumming interaction between an atomic system and a single cavity mode and show how to employ it in reservoir engineering processes. To construct the effective Hamiltonian, we analyse considered the interaction of an atomic system in a \{Lambda} configuration, driven by classical fields, with a single cavity mode. With this interaction, we firstly show how to generate a decoherence-free displaced squeezed state for the cavity field. In our scheme, an atomic beam works as a reservoir for the radiation field trapped inside the cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401 (2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in high-Q resonators. In our scheme, all the atoms have to be prepared in the ground state and, as in the cited article, neither atomic detection nor precise interaction times between the atoms and the cavity mode are required. From this same interaction, we can also generate an ideal squeezed reservoir for atomic systems. For this purpose we have to assume, besides the engineered atom-field interaction, a strong decay of the cavity field (i.e., the cavity decay must be much stronger than the effective atom-field coupling). With this scheme, some interesting effects in the dynamics of an atom in a squeezed reservoir could be tested.
Study of novel natural compounds as potential drugs in the treatment of acute leukemias
Creators: name: Ferruzzi, Lorenzo <1985>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: BIO/14 Farmacologia

description: Introduction: Among all cancer types leukemia represents the leading cause of cancer death in man younger than 40 years. Single-target drug therapy has generally been highly ineffective in treating complex diseases such as cancer. A growing interest has been directed toward multi-target drugs able to hit multiple targets. In this context, plant products, based on their intrinsic complexity, could represent an interesting and promising approach. Aim of the research followed during my PhD was to indentify and study novel natural compounds for the treatment of acute leukemias. Two potential multi-target drugs were identified in Hemidesmus indicus and piperlongumine.
Methodology/Principal Findings: A variety of cellular assays and flow cytometry were performed on different cell lines. We demonstrated that Hemidesmus modulates many components of intracellular signaling pathways involved in cell viability and proliferation and alters gene and protein expression, eventually leading to tumor cell death, mediated by a loss of mitochondrial transmembrane potential, raise of [Ca2+]i, inhibition of Mcl-1, increasing Bax/Bcl-2 ratio, and ROS formation. Moreover, we proved that the decoction causes differentiation of HL-60 and regulates angiogenesis of HUVECs in hypoxia and normoxia, by the inhibition of new vessel formation and the processes of migration/invasion. Clinically relevant observations are that its cytotoxic activity was also recorded in primary cells from acute myeloid leukemia (AML) patients. Moreover, both Hemidesmus and piperlongumine showed a selective action toward leukemic stem cell (LSC).
Conclusions: Our results indicate the molecular basis of the anti-leukemic effects of Hemidesmus indicus and indentify the mitochondrial pathways, [Ca2+]i, cytodifferentiation and angiogenesis inhibition as crucial actors in its anticancer activity. The ability to selectively hit LSC showed by Hemidesmus and piperlongumine enriched the knowledge of their anti-leukemic activity. On these bases, we conclude that Hemidesmus and piperlongumine can represent a valuable strategy in the anticancer pharmacology.