cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Asymmetric reproductive character displacement in male aggregation behaviour
Creators: name: Stewart, A. B.
name: Pfennig, K. S.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: Reproductive character displacement—the evolution of traits that minimize reproductive interactions between species—can promote striking divergence in male signals or female mate preferences between populations that do and do not occur with heterospecifics. However, reproductive character displacement can affect other aspects of mating behaviour. Indeed, avoidance of heterospecific interactions might contribute to spatial (or temporal) aggregation of conspecifics. We examined this possibility in two species of hybridizing spadefoot toad (genus Spea). We found that in Spea bombifrons sympatric males were more likely than allopatric males to associate with calling males. Moreover, contrary to allopatric males, sympatric S. bombifrons males preferentially associated with conspecific male calls. By contrast, Spea multiplicata showed no differences between sympatry and allopatry in likelihood to associate with calling males. Further, sympatric and allopatric males did not differ in preference for conspecifics. However, allopatric S. multiplicata were more variable than sympatric males in their responses. Thus, in S. multiplicata, character displacement may have refined pre-existing aggregation behaviour. Our results suggest that heterospecific interactions can foster aggregative behaviour that might ultimately contribute to clustering of conspecifics. Such clustering can generate spatial or temporal segregation of reproductive activities among species and ultimately promote reproductive isolation.
Host plant quality, selection history and trade-offs shape the immune responses of Manduca sexta
Creators: name: Kingsolver, J. G.
name: Diamond, S. E.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: Immune defences are an important component of fitness. Yet susceptibility to pathogens is common, suggesting the presence of ecological and evolutionary limitations on immune defences. Here, we use structural equation modelling to quantify the direct effects of resource quality and selection history, and their indirect effects mediated via body condition prior to an immune challenge on encapsulation and melanization immune defences in the tobacco hornworm, Manduca sexta. We also investigate allocation trade-offs among immune defences and growth rate following an immune challenge. We found considerable variation in the magnitude and direction of the direct effects of resource quality and selection history on immune defences and their indirect effects mediated via body condition and allocation trade-offs. Greater resource quality and evolutionary exposure to pathogens had positive direct effects on encapsulation and melanization. The indirect effect of resource quality on encapsulation mediated via body condition was substantial, whereas indirect effects on melanization were negligible. Individuals in better condition prior to the immune challenge had greater encapsulation; however, following the immune challenge, greater encapsulation traded off with slower growth rate. Our study demonstrates the importance of experimentally and analytically disentangling the relative contributions of direct and indirect effects to understand variation in immune defences.
Developing a model for neutron star oscillations following starquakes
Creators: name: Keer, L.
name: Jones, D. I.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Glitches -- sudden increases in spin rate -- are observed in many pulsars. One mechanism advanced to explain glitches in the youngest pulsars is that they are caused by a starquake, a sudden rearrangement of the crust of the neutron star. Starquakes have the potential to excite some of the oscillation modes of the neutron star, which means that they are of interest as a source of gravitational waves. These oscillations could also have an impact on radio emission. In this paper we make upper estimates of the amplitude of the oscillations produced by a starquake, and the corresponding gravitational wave emission. We then develop a more detailed framework for calculating the oscillations excited by the starquake, using a toy model of a solid, incompressible star where all strain is lost instantaneously from the star at the glitch. For this toy model, we give plots of the amplitudes of the modes excited, as the shear modulus and rotation rate of the star are varied. We find that for our specific model, the largest excitation is generally of a mode similar to the $f$-mode of an incompressible fluid star, but that other modes of the star are excited to a significant degree over small parameter ranges of the rotation rate.
description: 30 pages, 13 figures. Updated in response to referee's comments (additional explanation inserted, and some material moved to an Appendix). To appear in MNRAS
The role of developmental plasticity in evolutionary innovation
Creators: name: Abouheif, E.
name: Moczek, A. P.
name: Pfennig, D. W.
name: Nijhout, H. F.
name: Ledon-Rettig, C.
name: Sultan, S.
name: Foster, S.
name: Dworkin, I.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2011

description: Explaining the origins of novel traits is central to evolutionary biology. Longstanding theory suggests that developmental plasticity, the ability of an individual to modify its development in response to environmental conditions, might facilitate the evolution of novel traits. Yet whether and how such developmental flexibility promotes innovations that persist over evolutionary time remains unclear. Here, we examine three distinct ways by which developmental plasticity can promote evolutionary innovation. First, we show how the process of genetic accommodation provides a feasible and possibly common avenue by which environmentally induced phenotypes can become subject to heritable modification. Second, we posit that the developmental underpinnings of plasticity increase the degrees of freedom by which environmental and genetic factors influence ontogeny, thereby diversifying targets for evolutionary processes to act on and increasing opportunities for the construction of novel, functional and potentially adaptive phenotypes. Finally, we examine the developmental genetic architectures of environment-dependent trait expression, and highlight their specific implications for the evolutionary origin of novel traits. We critically review the empirical evidence supporting each of these processes, and propose future experiments and tests that would further illuminate the interplay between environmental factors, condition-dependent development, and the initiation and elaboration of novel phenotypes.
Dispersal, environmental niches and oceanic-scale turnover in deep-sea bivalves
Creators: name: Stegen, J. C.
name: McClain, C. R.
name: Hurlbert, A. H.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: Patterns of beta-diversity or distance decay at oceanic scales are completely unknown for deep-sea communities. Even when appropriate data exist, methodological problems have made it difficult to discern the relative roles of environmental filtering and dispersal limitation for generating faunal turnover patterns. Here, we combine a spatially extensive dataset on deep-sea bivalves with a model incorporating ecological dynamics and shared evolutionary history to quantify the effects of environmental filtering and dispersal limitation. Both the model and empirical data are used to relate functional, taxonomic and phylogenetic similarity between communities to environmental and spatial distances separating them for 270 sites across the Atlantic Ocean. This study represents the first ocean-wide analysis examining distance decay as a function of a broad suite of explanatory variables. We find that both strong environmental filtering and dispersal limitation drive turnover in taxonomic, functional and phylogenetic composition in deep-sea bivalves, explaining 26 per cent, 34 per cent and 9 per cent of the variation, respectively. This contrasts with previous suggestions that dispersal is not limiting in broad-scale biogeographic and biodiversity patterning in marine systems. However, rates of decay in similarity with environmental distance were eightfold to 44-fold steeper than with spatial distance. Energy availability is the most influential environmental variable evaluated, accounting for 3.9 per cent, 9.4 per cent and 22.3 per cent of the variation in functional, phylogenetic and taxonomic similarity, respectively. Comparing empirical patterns with process-based theoretical predictions provided quantitative estimates of dispersal limitation and niche breadth, indicating that 95 per cent of deep-sea bivalve propagules will be able to persist in environments that deviate from their optimum by up to 2.1 g m−2 yr−1 and typically disperse 749 km from their natal site.
A formalism to assess the accuracy of nuclear-structure weak interaction effects in precision $β$-decay studies
Creators: name: Glick-Magid, Ayala
name: Gazit, Doron
Publisher: name: arXiv
Year: 2021
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Multiple high precision $β$-decay measurements are being carried out these days on various nuclei, in search of beyond the Standard Model signatures. These measurements necessitate accurate standard model theoretical predictions to be compared with. Motivated by the experimental surge, we present a formalism for such a calculation of $β$-decay observables, with controlled accuracy, based on a perturbative analysis of the theoretical observables related to the phenomena, including high order nuclear recoil and shape corrections. The accuracy of the corrections is analyzed by identifying a hierarchy of small parameters, related to the low momentum transfer characterizing $β$-decays. Furthermore, we show that the sub-percent uncertainties, targeted by on-going and planned experiments, entail an accuracy of the order of 10\% for the solution of the nuclear many body problem, which is well within the reach of modern nuclear theory for light to medium mass nuclei.
Das westliche Verständnis des Körpers als globale Perspektive
Creators: name: Akashe-Böhme, Farideh
Publisher: name: Concilium
Year: 1970

description: Concilium, Bd. 38 Nr. 2 (2002): Concilium: Internationale Zeitschrift für Theologie, Band 38, Heft 2
On diagrammatic technique for nonlinear dynamical systems
Creators: name: Semenyakin, Mykola
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Classical Analysis and ODEs (math.CA)
subject: Dynamical Systems (math.DS)
subject: Rings and Algebras (math.RA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: In this paper we investigate phase flows over $\mathbb{C}^n$ and $\mathbb{R}^n$ generated by vector fields $V=\sum P^{i}\partial_i$ where $P^{i}$ are finite degree polynomials. With the convenient diagrammatic technique we get expressions for evolution operators $ev\{V|t\}: x(0)\mapsto x(t)$ through the series in powers of $x(0)$ and $t$, represented as sum over all trees of particular type. Estimates are made for the radius of convergence in some particular cases. The phase flows behavior in the neighborhood of vector field fixed points are examined. Resonance cases are considered separately.
description: 5 figures
Strong bulk spin-orbit torques quantified in the van der Waals ferromagnet Fe3GeTe2
Creators: name: Martin, Franziska
name: Lee, Kyujoon
name: Schmitt, Maurice
name: Liedtke, Anna
name: Shahee, Aga
name: Simensen, Haakon Thømt
name: Scholz, Tanja
name: Saunderson, Tom G.
name: Go, Dongwook
name: Gradhand, Martin
name: Mokrousov, Yuriy
name: Denneulin, Thibaud
name: Kovács, András
name: Lotsch, Bettina
name: Brataas, Arne
name: Kläui, Mathias
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The recent emergence of magnetic van der Waals materials allows for the investigation of current induced magnetization manipulation in two dimensional materials. Uniquely, Fe3GeTe2 has a crystalline structure that allows for the presence of bulk spin-orbit torques (SOTs), that we quantify in a Fe3GeTe2 flake. From the symmetry of the measured torques, we identify the current induced effective fields using harmonic analysis and find dominant bulk SOTs, which arise from the symmetry in the crystal structure. Our results show that Fe3GeTe2 uniquely can exhibit bulk SOTs in addition to the conventional interfacial SOTs enabling magnetization manipulation even in thick single layers without the need for complex multilayer engineering.
description: 19 pages 4 figures
Evolving ecological networks and the emergence of biodiversity patterns across temperature gradients
Creators: name: Stegen, J. C.
name: Enquist, B. J.
name: Ferriere, R.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: In ectothermic organisms, it is hypothesized that metabolic rates mediate influences of temperature on the ecological and evolutionary processes governing biodiversity. However, it is unclear how and to what extent the influence of temperature on metabolism scales up to shape large-scale diversity patterns. In order to clarify the roles of temperature and metabolism, new theory is needed. Here, we establish such theory and model eco-evolutionary dynamics of trophic networks along a broad temperature gradient. In the model temperature can influence, via metabolism, resource supply, consumers' vital rates and mutation rate. Mutation causes heritable variation in consumer body size, which diversifies and governs consumer function in the ecological network. The model predicts diversity to increase with temperature if resource supply is temperature-dependent, whereas temperature-dependent consumer vital rates cause diversity to decrease with increasing temperature. When combining both thermal dependencies, a unimodal temperature–diversity pattern evolves, which is reinforced by temperature-dependent mutation rate. Studying coexistence criteria for two consumers showed that these outcomes are owing to temperature effects on mutual invasibility and facilitation. Our theory shows how and why metabolism can influence diversity, generates predictions useful for understanding biodiversity gradients and represents an extendable framework that could include factors such as colonization history and niche conservatism.
Διαφήμιση στο διαδίκτυο : προστασία του καταναλωτή
Creators: name: Κωνσταντακοπούλου, Δήμητρα
Publisher: name: Πανεπιστήμιο Πειραιώς
Year: 2023
Subjects: subject: Ανάγκες
subject: Αγαθά
subject: Μάρκετινγκ
subject: Επιχείρηση
subject: Κέρδος
subject: Brand name
subject: Πωλήσεις
subject: Αγορά
subject: Προϊόν
subject: Τιμή
subject: Ψηφιακό μάρκετινγκ
subject: Διαδίκτυο
subject: Εξυπηρέτηση πελατών
subject: Αρχή της αλήθειας
subject: Μέσα κοινωνικής δικτύωσης
subject: Ηλεκτρονικό εμπόριο

description: Στο πλαίσιο του Διατμηματικού Προγράμματος Μεταπτυχιακών Σπουδών «Δίκαιο και Οικονομία» του Πανεπιστημίου Πειραιώς, εκπονήθηκε η παρούσα διπλωματική εργασία με θέμα «Διαφήμιση στο Διαδίκτυο: Προστασία του Καταναλωτή». Περιλαμβάνει πέντε κεφάλαια προκειμένου να γίνει κατανοητή η αλληλουχία που υπάρχει στις έννοιες του μάρκετινγκ, της διαφήμισης, του ηλεκτρονικού εμπορίου και της προστασίας του καταναλωτή. Γίνεται αναφορά στο νομικό πλαίσιο της διαδικτυακής διαφήμισης, στις μορφές διαφημιστικής προβολής στο διαδίκτυο, στον τρόπο προβολής της στα μέσα κοινωνικής δικτύωσης, στα πλεονεκτήματα και μειονεκτήματά της. Εξετάζεται η έννοια του ηλεκτρονικού εμπορίου, το νομοθετικό του πλαίσιο καθώς και η κορύφωσή του μετά στην πανδημία, ενώ παρατίθενται τα πλεονεκτήματα και μειονεκτήματά του και εξετάζεται η μελλοντική του προοπτική. Η έννοια του καταναλωτή περιγράφεται αναλυτικά στο τέταρτο κεφάλαιο της παρούσας εργασίας, αναφέρεται το πρότυπο του «μέσου καταναλωτή» που προστατεύεται από το δίκαιο και περιγράφονται λεπτομερώς οι περιπτώσεις εκείνες για τις οποίες χρήζει προστασίας. Ειδική αναφορά γίνεται στις ρυθμίσεις του ΠΔ 131/2003 για τη μη ζητηθείσα εμπορική επικοινωνία και προβάλλονται τα νομικά εφόδια. Εξετάζονται επίσης, το Δίκτυο Συνεργασίας για την Προστασία των καταναλωτών για τις διασυνοριακές αγορές με τον επικαιροποιημένο κανονισμό (ΕΕ) 2017/2394 του Ευρωπαϊκού Κοινοβουλίου και του Συμβουλίου, ενώ ιδιαίτερη αναφορά γίνεται στην προστασία των ανήλικων καταναλωτών. Το τελευταίο κεφάλαιο ασχολείται με την Οδηγία 2019/2161/ΕΕ, που είναι γνωστή ως «Νέα Συμφωνία για τους Καταναλωτές» ("New Deal for Consumers"), η οποία αποσκοπεί στην κάλυψη κενών, που διαπιστώθηκαν μετά την αξιολόγηση του θεσμικού πλαισίου με την ψηφιακή αγορά και εξετάζεται αναλυτικά ο Ν. 4933 ΦΕΚ Α 99/20.5.2022, με τον οποίο έγινε η προσαρμογή της στην ελληνική νομοθεσία και οι τροποποιήσεις που επέφερε. Σκοπός της Οδηγίας αυτής είναι η αύξηση της προστασίας και της εμπιστοσύνης των καταναλωτών στην Ένωση, ως το πιο ευάλωτο μέρος σε μία συναλλαγή και στην πίστη ότι όλοι οι καταναλωτές-πολίτες της Ένωσης, έχουν τα ίδια δικαιώματα και αντιμετωπίζονται κοινά στην κοινή ευρωπαϊκή αγορά.
Morphological and kinematic basis of the hummingbird flight stroke: scaling of flight muscle transmission ratio
Creators: name: Hedrick, T. L.
name: Tobalske, B. W.
name: Biewener, A. A.
name: Ros, I. G.
name: Warrick, D. R.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2012

description: Hummingbirds (Trochilidae) are widely known for their insect-like flight strokes characterized by high wing beat frequency, small muscle strains and a highly supinated wing orientation during upstroke that allows for lift production in both halves of the stroke cycle. Here, we show that hummingbirds achieve these functional traits within the limits imposed by a vertebrate endoskeleton and muscle physiology by accentuating a wing inversion mechanism found in other birds and using long-axis rotational movement of the humerus. In hummingbirds, long-axis rotation of the humerus creates additional wing translational movement, supplementing that produced by the humeral elevation and depression movements of a typical avian flight stroke. This adaptation increases the wing-to-muscle-transmission ratio, and is emblematic of a widespread scaling trend among flying animals whereby wing-to-muscle-transmission ratio varies inversely with mass, allowing animals of vastly different sizes to accommodate aerodynamic, biomechanical and physiological constraints on muscle-powered flapping flight.
title: Synthesis, Structure and Reactivity of Cyclopenta-annulated 1,2,3,4-Tetrazines
Creators: name: Mackert, Peter J.
name: Hafner, Klaus
name: Nimmerfroh, Norbert
name: Banert, Klaus
Publisher: name: Wiley
Year: 2023

description: The 2-aryl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3a-n are formed by coupling of the diazocyclopentadienes 1a and 1b with arenediazonium salts and subsequent reversible electrocyclization of the primary coupling products 2a-n. From the solutions of the equilibrium mixtures of 2a ⇌ 3a - 2n ⇌ 3n the tetrazines 3a-d, h-k and the arylazo-diazocyclopentadienes 2e-g and 21-n crystallize. The 2-methyl-2H-cyclopenta[e]-1,2,3,4-tetrazines 3o and 3p are obtained by addition of methyllithium to 1a and 1b followed by a diazo transfer reaction and cyclization. In solutions of 3o and 3p the ring-opened isomers 2o and 2p could not be detected. X-ray analyses of 3h and 3p prove their bicyclic planar geometry in the solid state. ¹⁵N-NMR and temperature-dependent ¹H-NMR spectroscopy have enabled a detailed study of the reversible ring closure reaction in the case of 2d ⇌ 3d. Reaction of 2-phenyl-2H-cyclopenta[e]-1,2,3,4-tetrazine (3b) with tetrafluoroboric acid results in the formation of the protonated monocyclic salt 4. Furthermore 3b undergoes electrophilic substitution reactions preferably at C-7, as demonstrated by bromination, formylation, and trifluoroacetylation. Photolysis of solutions of 2i/3i, 2k/3k, and 21/31 leads to the ketene imines 11a-c. The structure of 11c has been determined by X-ray crystallography.
On the motion of hairpin filaments in the atmospheric boundary layer
Creators: name: Harikrishnan, Abhishek
name: Rodal, Marie
name: Klein, Rupert
name: Margerit, Daniel
name: Vercauteren, Nikki
Publisher: name: Freie Universität Berlin
Year: 2023
Subjects: subject: atmospheric boundary layer
subject: hairpin filaments
subject: motion
subject: 500 Naturwissenschaften und Mathematik::530 Physik::530 Physik

description: A recent work of Harikrishnan et al. [“Geometry and organization of coherent structures in stably stratified atmospheric boundary layers,” arXiv:2110.02253 (2021)] has revealed an abundance of hairpin-like vortex structures, oriented in a similar direction, in the turbulent patches of a stably stratified Ekman flow. In this study, hairpin-like structures are investigated by treating them as slender vortex filaments, i.e., a vortex filament whose diameter d is small when compared to its radius of curvature R. The corrected thin-tube model of Klein and Knio [“Asymptotic vorticity structure and numerical simulation of slender vortex filaments,” J. Fluid Mech. 284, 275 (1995)] is used to compute the motion of these filaments with the atmospheric boundary layer as a background flow. Our results suggest that the orientation of the hairpin filament in the spanwise direction is linked to its initial starting height under stable stratification, whereas no such dependency can be observed with the neutrally stratified background flow. An improved feature tracking scheme based on spatial overlap for tracking Q-criterion vortex structures on the direct numerical simulation data is also developed. It overcomes the limitation of using a constant threshold in time by dynamically adjusting the thresholds to accommodate the growth or deterioration of a feature. A comparison between the feature tracking and the filament simulation reveals qualitatively similar temporal developments. Finally, an extension of the asymptotic analysis of Callegari and Ting [“Motion of a curved vortex filament with decaying vortical core and axial velocity,” J. Appl. Math. 35, 148–175 (1978)] is carried out to include the effect of gravity. The results show that, in the regime considered here, a contribution from the gravity term occurs only when the tail of an infinitely long filament is tilted at an angle relative to the wall.
Resource-Efficient Gigawatt Water Electrolysis in Germany—A Circular Economy Potential Analysis
Creators: name: Matz, Levin
name: Bensmann, Boris
name: Hanke-Rauschenbach, Richard
name: Minke, Christine
Publisher: name: [Cham] : Springer International Publishing
Year: 2024
Subjects: subject: 3 R’s
subject: Alkaline water electrolysis
subject: Circular economy
subject: Hydrogen economy
subject: Proton exchange membrane water electrolysis
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::330 | Wirtschaft

description: Green hydrogen will play a key role in the future energy system. For the production of green hydrogen, an installation of alkaline (AWE) and proton exchange membrane water electrolysis (PEMWE) of several gigawatts per year is projected in the upcoming decades. The development of the hydrogen economy is associated with a great demand for scarce and expensive resources. To reduce resource demand and avoid supply bottlenecks, actions toward a circular economy are required. In the present study, three circular economy actions (repair, reuse, and recycling) are analyzed with regard to AWE and PEMWE installation taking Germany as an example. It is found that, so far, only recycling is a viable strategy for a circular economy. For further analysis, a model is developed to assess the impact of recycling on resource demand for AWE and PEMWE scale-up. Mass flows from end-of-life recycling are intergrated into the model, and their economic value is estimated. The results imply that closed-loop recycling can reduce the cumulated primary resource demand by up to 50% in the long run. However, recycling will first be relevant after 2040, while water electrolysis capacities installed before still depend on primary materials. The outlook on the economic value of the recycling materials indicates a volume of up to 2.15 B € per decade for PEMWE and 0.98 B € per decade for AWE recycling. To realize the potential, a recycling industry specialized for those technolgies considering the whole value chain covering dismantling, collection, and recycling must be introduced.
Evolution of displays within the pair bond
Creators: name: Price, T. D.
name: Servedio, M. R.
name: Lande, R.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2013

description: Although sexual selection is an important cause of display evolution, in socially monogamous species (e.g. many birds), displays continue after formation of the pair bond. Here, we consider that these displays evolve because they stimulate the partner to increase investment in offspring. Our study is motivated by elaborate mutual displays in species that are largely monomorphic and have long-term pair bonds (e.g. the great crested grebe, Podiceps cristatus) and by many empirical results evidencing that display manipulation affects parental investment. Using population genetic models, we show that a necessary condition for the permanent establishment of mutual displays in the pair bond is that the benefit of investment by the pair is more than twice that resulting from investment by a single individual. Pre-existing biases to respond to displays by increased investment are a necessary component of display evolution. We also consider examples where one sex (e.g. males) stimulates increased investment in offspring by the other sex. Here, display and additional investment cannot evolve permanently, but can increase and linger at high frequency for a long time before loss. We discuss how such transient effects may lead to the evolution of permanent displays as a result of evolution at additional loci.
Effect of geometric disorder on chaotic viscoelastic porous media flows
Creators: name: Chauhan, A.
name: Gupta, S.
name: Sasmal, C.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: The flow of viscoelastic fluids in porous media is encountered in many practical applications, such as in the enhanced oil recovery process or in the groundwater remediation. Once the flow rate exceeds a critical value in such flows, an elastic instability with fluctuating flow field is observed, which ultimately transits to a more chaotic and turbulence-like flow structure as the flow rate further increases. In a recent study, it has been experimentally shown that this chaotic flow behaviour of viscoelastic fluids can be suppressed by increasing the geometric disorder in a model porous media consisting of a microchannel with several micropillars placed in it. However, the present numerical study demonstrates that this is not always true. We show that it depends on the initial arrangement of the micropillars for mimicking the porous media. In particular, we find that for an initial ordered and aligned configuration of the micropillars, the introduction of geometric order actually increases the chaotic flow dynamics as opposed to that seen for an initial ordered and staggered configuration of the micropillars. We suggest that this chaotic flow behaviour actually depends on the number of the stagnation points revealed to the flow field where maximum stretching of the viscoelastic microstructure happens. Our findings and explanation are perfectly in line with that observed and provided in a more recent experimental study.
Intraspecific morphological and genetic variation of common species predicts ranges of threatened ones
Creators: name: Mila, B.
name: Saatchi, S.
name: Fuller, T. L.
name: Peralvo, M.
name: Mason, E.
name: Schweizer, R. M.
name: Wayne, R. K.
name: Devitt, S. E. C.
name: Schneider, C. J.
name: Wang, O.
name: Kieswetter, C. M.
name: Thomassen, H. A.
name: Chan, J.
name: Pollinger, J. P.
name: Buermann, W.
name: Smith, T. B.
name: Jarrin-V, P.
name: Schlunegger, J.
name: Graham, C. H.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2013

description: Predicting where threatened species occur is useful for making informed conservation decisions. However, because they are usually rare, surveying threatened species is often expensive and time intensive. Here, we show how regions where common species exhibit high genetic and morphological divergence among populations can be used to predict the occurrence of species of conservation concern. Intraspecific variation of common species of birds, bats and frogs from Ecuador were found to be a significantly better predictor for the occurrence of threatened species than suites of environmental variables or the occurrence of amphibians and birds. Fully 93 per cent of the threatened species analysed had their range adequately represented by the geographical distribution of the morphological and genetic variation found in seven common species. Both higher numbers of threatened species and greater genetic and morphological variation of common species occurred along elevation gradients. Higher levels of intraspecific divergence may be the result of disruptive selection and/or introgression along gradients. We suggest that collecting data on genetic and morphological variation in common species can be a cost effective tool for conservation planning, and that future biodiversity inventories include surveying genetic and morphological data of common species whenever feasible.
Supplementary document for Soft-X-ray nanobeams formed by aberration-reduced elliptical mirrors with large numerical aperture - 6673493.pdf
Creators: name: Shimamura, Takenori
name: Takeo, Yoko
name: Kimura, Takashi
name: Senba, Yasunori
name: Kishimoto, Hikaru
name: Ohashi, Haruhiko
name: Mimura, Hidekazu
Publisher: name: Optica Publishing Group
Year: 2023
Subjects: Uncategorized

description: Supplemental fabrication details
Spatiotemporal modelling of PM 2.5 concentrations in Lombardy (Italy): a comparative study
Creators: name: Otto, Philipp
name: Fusta Moro, Alessandro
name: Rodeschini, Jacopo
name: Shaboviq, Qendrim
name: Ignaccolo, Rosaria
name: Golini, Natalia
name: Cameletti, Michela
name: Maranzano, Paolo
name: Finazzi, Francesco
name: Fassò, Alessandro
Publisher: name: Dordrecht [u.a.] : Springer Science + Business Media B.V
Year: 2024
Subjects: subject: Air pollution
subject: Generalised additive mixed model
subject: Geostatistics
subject: Hidden dynamic geostatistical model
subject: Machine learning
subject: Random forest spatiotemporal kriging
subject: Spatiotemporal process
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::310 | Statistik

description: This study presents a comparative analysis of three predictive models with an increasing degree of flexibility: hidden dynamic geostatistical models (HDGM), generalised additive mixed models (GAMM), and the random forest spatiotemporal kriging models (RFSTK). These models are evaluated for their effectiveness in predicting PM 2.5 concentrations in Lombardy (North Italy) from 2016 to 2020. Despite differing methodologies, all models demonstrate proficient capture of spatiotemporal patterns within air pollution data with similar out-of-sample performance. Furthermore, the study delves into station-specific analyses, revealing variable model performance contingent on localised conditions. Model interpretation, facilitated by parametric coefficient analysis and partial dependence plots, unveils consistent associations between predictor variables and PM 2.5 concentrations. Despite nuanced variations in modelling spatiotemporal correlations, all models effectively accounted for the underlying dependence. In summary, this study underscores the efficacy of conventional techniques in modelling correlated spatiotemporal data, concurrently highlighting the complementary potential of Machine Learning and classical statistical approaches.
A novel process chain for the automated repair of leading edges in aircraft engines
Creators: name: Kenneweg, Robert
name: Heide, Klaas Maximilian
name: Böß, Volker
name: Denkena, Berend
name: Westermann, Hans-Henrik
Publisher: name: Berlin ; Heidelberg : Springer
Year: 2024
Subjects: subject: Adaptive manufacturing
subject: Automation
subject: In-process measurement
subject: Maintenance
subject: Manufacturing system
subject: Sensor
subject: Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau

description: Due to impacts and constant stress, the leading edges of aircraft engine blades often lose their shape, while the other parts of the blade are still functional. This results in unnecessary performance losses. Currently, there is no method for a fast and effective repair process as the initial shape of the blade cannot be restored. This paper presents an automated re-contouring process chain for leading edges without prior material application. Thus, it is a sustainable approach to extend the lifespan until an energy-consuming welding process can be performed. It consists of an in-machine scanning process to obtain information about the worn shape, a subsequent target model generation based on the worn shape, and an automated process planning. The process chain is evaluated using a universal, leading edge workpiece. The results show that the target requirements for shape and smoothness are fulfilled.
Lorentzian 2d CFT from the pAQFT perspective
Creators: name: Crawford, Sam
name: Rejzner, Kasia
name: Vicedo, Benoit
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We provide a detailed construction of the quantum theory of the massless scalar field on 2-dimensional, globally-hyperbolic (in particular, Lorentzian) manifolds using the framework of perturbative algebraic quantum field theory. From this we subalgebras of observables isomorphic to the Heisenberg and Virasoro algebras on the Einstein cylinder. We also show how the conformal version of general covariance, as first introduced by Pinamonti as an extension of the construction due to Brunetti, Fredenhagen and Verch, may be applied to the concept of natural Lagrangians in order to obtain a simple condition for the conformal covariance of classical dynamics, which is then shown to quantise in the case of a quadratic Lagrangian. We then compare the covariance condition for the stress-energy tensor in the classical and quantum theory in Minkowksi space, obtaining a transformation law dependent on the Schwarzian derivative of the transformed coordinate, in accordance with a well-known result in the Euclidean literature.
Testing magnetic tracers as indicators of sediment transport in a wave flume experiment
Creators: name: Romão, Soraia
name: Cascalho, João
name: Ferreira, Caroline C.
name: Font, Eric
name: Taborda, Rui
name: Silva, Paulo A.
name: Duarte, João F.
name: Staudt, Franziska
Publisher: name: Oxford : Wiley-Blackwell
Year: 2024
Subjects: subject: Flume experiment
subject: isothermal remanent magnetization
subject: magnetic susceptibility
subject: magnetic tracers
subject: sediment tracking
subject: sediment transport
subject: Dewey Decimal Classification::500 | Naturwissenschaften::550 | Geowissenschaften

description: The in situ measurement of sediment transport in wave-dominated environments presents significant challenges and currently often relies upon the use of fluorescent sediment tracers. However, this method is constrained by challenges in conducting unbiased and representative sampling, as well as facing overall logistical complexities and labour-intensive procedures. Whilst other tracer techniques are available, such as using magnetic tracers, their performance in tracking sediment transport has not been quantified. The objective of this study is to assess the effectiveness of magnetic tracers in evaluating net transport rates and tracer dispersal patterns. Conducted in a controlled large wave flume, the experiments simultaneously employed fluorescent and magnetic tracers, allowing a comprehensive comparison of the tracers' dispersion patterns and the net transport rates. Results show that the dispersal of magnetic and fluorescent tracers displays a high degree of spatial coherence in both horizontal and vertical dimensions. Similarly, net transport rates are comparable (<16% difference), both showing net transport in the direction of the wave propagation (towards onshore) driven by non-linear and streaming effects. Magnetic tracer recovery rate (49%) was lower than for fluorescent tracers (73%) and is attributed to the loss of magnetic ink from particles; an aspect of the magnetic technique that requires improvement. This study therefore indicates that the use of magnetic tracers to quantify sediment transport is an effective method with the advantages of being significantly less labour-intensive than using the commonly applied fluorescent sediment tracer method.
Reinforcement generates reproductive isolation between neighbouring conspecific populations of spadefoot toads
Creators: name: Rice, A. M.
name: Pfennig, K. S.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2014

description: Reproductive character displacement is the adaptive evolution of traits that minimize deleterious reproductive interactions between species. When arising from selection to avoid hybridization, this process is referred to as reinforcement. Reproductive character displacement generates divergence not only between interacting species, but also between conspecific populations that are sympatric with heterospecifics versus those that are allopatric. Consequently, such conspecific populations can become reproductively isolated. We compared female mate preferences in, and evaluated gene flow between, neighbouring populations of spadefoot toads that did and did not occur with heterospecifics (mixed- and pure-species populations, respectively). We found that in mixed-species populations females significantly preferred conspecifics. Such females also tended to prefer a conspecific call character that was dissimilar from heterospecifics. By contrast, females from pure-species populations did not discriminate conspecific from heterospecific calls. They also preferred a more exaggerated conspecific call character that resembles heterospecific males. Moreover, gene flow was significantly reduced between mixed- and pure-species population types. Thus, character displacement (and, more specifically, reinforcement) may initiate reproductive isolation between conspecific populations that differ in interactions with heterospecifics.
Experimental Heat Transfer Coefficients for Zeotropic Mixture Condensation of Hexamethyldisiloxane/Octamethyltrisiloxane and Ethanol/Hexamethyldisiloxane
Creators: name: Zimmermann, Conrad
name: Lubos, Nico
name: Kabelac, Stephan
Publisher: name: Weinheim : Wiley-VCH Verl.
Year: 2024
Subjects: subject: Condensation
subject: Heat transfer
subject: Laminar film
subject: Mixture
subject: Siloxane
subject: Dewey Decimal Classification::500 | Naturwissenschaften::540 | Chemie
subject: Dewey Decimal Classification::600 | Technik::660 | Technische Chemie

description: Legal requirements for refrigerants necessitate a continuous development of these fluids, also focusing on mixtures. This article contributes three aspects to the ongoing research: (1) Experimental mean heat transfer coefficients were determined for the condensation of two novel zeotropic mixtures, hexamethyldisiloxane (MM)/octamethyltrisiloxane and ethanol/MM, gathered for filmwise condensation on a vertical tube. (2) Both mixtures were investigated with several compositions to provide a comprehensive understanding of the mixture effects. (3) The results were taken to develop a novel superposition approach to predict mixture condensation.
The geomagnetic environment in which sea turtle eggs incubate affects subsequent magnetic navigation behaviour of hatchlings
Creators: name: Davidoff, K. R.
name: Mangiamele, L. A.
name: Fuxjager, M. J.
name: Lohmann, K. J.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2014

description: Loggerhead sea turtle hatchlings (Caretta caretta) use regional magnetic fields as open-ocean navigational markers during trans-oceanic migrations. Little is known, however, about the ontogeny of this behaviour. As a first step towards investigating whether the magnetic environment in which hatchlings develop affects subsequent magnetic orientation behaviour, eggs deposited by nesting female loggerheads were permitted to develop in situ either in the natural ambient magnetic field or in a magnetic field distorted by magnets placed around the nest. In orientation experiments, hatchlings that developed in the normal ambient field oriented approximately south when exposed to a field that exists near the northern coast of Portugal, a direction consistent with their migratory route in the northeastern Atlantic. By contrast, hatchlings that developed in a distorted magnetic field had orientation indistinguishable from random when tested in the same north Portugal field. No differences existed between the two groups in orientation assays involving responses to orbital movements of waves or sea-finding, neither of which involves magnetic field perception. These findings, to our knowledge, demonstrate for the first time that the magnetic environment present during early development can influence the magnetic orientation behaviour of a neonatal migratory animal.
Electron Beam Ion Sources
Creators: name: Zschornacka, G.
name: Schmidt, M.
name: Thorn, A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Accelerator Physics (physics.acc-ph)
subject: FOS: Physical sciences

description: Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.
description: 37 pages, contribution to the CAS-CERN Accelerator School: Ion Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Bailey
Electoral Campaigns and Parliamentary Practice: Do Parties Pursue the Issues They Campaigned On?
Creators: name: Gross, Martin
name: Nyhuis, Dominic
name: Block, Sebastian
name: Velimsky, Jan A.
Publisher: name: Hoboken, NJ [u.a.] : Wiley
Year: 2024
Subjects: subject: Electoral Campaigns
subject: Issue Attention
subject: Local Politics
subject: Parliaments
subject: Party Manifestos
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::320 | Politik

description: Well-functioning political representation presupposes that the substantive focus of parties‘ parliamentary efforts reflects the issues on which parties campaigned. Although the link between electoral campaigning and parliamentary practice is crucial for successful representation in modern democracies, we still have little evidence that the issues on which political actors campaigned are the ones they focus on in day-to-day politics. We investigate the link between electoral campaigning and parliamentary practice by examining the overlap between parties‘ issue attention in manifestos and parliamentary questions. Our results for parties‘ issue attention in local campaigns and in local councils in Germany between 2011 and 2020 show that parties follow up on the issues they campaign on: The more parties emphasise an issue in their campaign, the more they pay attention to it in their parliamentary activities.
The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming
Creators: name: Westfield, I. T.
name: Bruno, J. F.
name: Ries, J. B.
name: Castillo, K. D.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2014

description: Anthropogenic increases in atmospheric CO2 over this century are predicted to cause global average surface ocean pH to decline by 0.1–0.3 pH units and sea surface temperature to increase by 1–4°C. We conducted controlled laboratory experiments to investigate the impacts of CO2-induced ocean acidification (pCO2 = 324, 477, 604, 2553 µatm) and warming (25, 28, 32°C) on the calcification rate of the zooxanthellate scleractinian coral Siderastrea siderea, a widespread, abundant and keystone reef-builder in the Caribbean Sea. We show that both acidification and warming cause a parabolic response in the calcification rate within this coral species. Moderate increases in pCO2 and warming, relative to near-present-day values, enhanced coral calcification, with calcification rates declining under the highest pCO2 and thermal conditions. Equivalent responses to acidification and warming were exhibited by colonies across reef zones and the parabolic nature of the corals' response to these stressors was evident across all three of the experiment's 30-day observational intervals. Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate—suggesting that ocean warming poses a more immediate threat than acidification for this important coral species.
Network log-ARCH models for forecasting stock market volatility
Creators: name: Mattera, Raffaele
name: Otto, Philipp
Publisher: name: Amsterdam [u.a.] : Elsevier Science
Year: 2024
Subjects: subject: ARCH models
subject: Financial networks
subject: Network processes
subject: Risk prediction
subject: Spatial econometrics
subject: Stock market volatility
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie
subject: Dewey Decimal Classification::300 | Sozialwissenschaften, Soziologie, Anthropologie::330 | Wirtschaft
subject: Dewey Decimal Classification::600 | Technik::650 | Management

description: This paper presents a dynamic network autoregressive conditional heteroscedasticity (ARCH) model suitable for high-dimensional cases where multivariate ARCH models are typically no longer applicable. We adopt the theoretical foundations from spatiotemporal statistics and transfer the dynamic ARCH model processes to networks. The model integrates temporally lagged volatility and information from adjacent nodes, which may instantaneously spill across the entire network. The model is used to forecast volatility in the US stock market, and the edges are determined based on various distance and correlation measures between the time series. The performance of alternative network definitions is compared with independent univariate log-ARCH models in terms of out-of-sample prediction accuracy. The results indicate that more accurate forecasts are obtained with network-based models and that accuracy can be improved by combining the forecasts of different network definitions. We emphasise the significance for practitioners to integrate network structure information when developing volatility forecasts.