The geometry of L^p-spaces over atomless measure spaces and the Daugavet property

We show that $L^p$-spaces over atomless measure spaces can be characterized in terms of a $p$-concavity type geometric property that is related with the Daugavet property

Spin budget of the proton at NNLO and beyond

We revisit the scale evolution of the quark and gluon spin contributions to the proton spin, 1 2 ΔΣ and ΔG, using the three-loop results for the spin-dependent evolution kernels available in the literature. We argue that the evolution of the quark spin contribution may actually be extended to the four-loop order, and that to all orders a single anomalous dimension governs the evolution of both ΔΣ and ΔG. We present analytical solutions of the evolution equations for ΔΣ and ΔG and investigate their scale dependence both to large and down to lower “hadronic” scales. We find that the solutions remain perturbatively stable even to low scales, where they come closer to simple quark model expectations. We discuss a curious scenario for the proton spin, in which even the gluon spin contribution is essentially scale independent and has a finite asymptotic value as the scale becomes large. We finally also show that perturbative three-loop evolution leads to a larger spin contribution of strange antiquarks than of strange quarks.Fil: de Florian, Daniel Enrique. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vogelsang, Werner. Tübingen University. Institute for Theoretical Physics; Alemani

THE DAUGAVET EQUATION FOR BOUNDED VECTOR-VALUED FUNCTIONS

[EN] Requirements under which the Daugavet equation and the alternative Daugavet equation hold for pairs of nonlinear maps between Banach spaces are analyzed. A geometric description is given in terms of nonlinear slices. Some local versions of these properties are also introduced and studied, as well as tests for checking whether the required conditions are satisfied in relevant cases.The authors were supported by the Ministerio de Economia y Competitividad (Spain), research project No. MTM2012-36740-C02-02.Brach, S.; Sánchez Pérez, EA.; Werner, D. (2017). THE DAUGAVET EQUATION FOR BOUNDED VECTOR-VALUED FUNCTIONS. Rocky Mountain Journal of Mathematics. 47(6):1765-1801. doi:10.1216/RMJ-2017-47-6-1765S1765180147

Threshold resummation at N LL 3 accuracy and approximate N3LO corrections to semi-inclusive DIS

We advance the threshold resummation formalism for semi-inclusive deep-inelastic scattering (SIDIS) to next-to-next-to-next-to-leading logarithmic (NLL3) order, including the three-loop hard factor. We expand the results in the strong coupling to obtain approximate next-to-next-to-next-to-leading order (N3LO) corrections for the SIDIS cross section. In Mellin moment space, these corrections include all terms that are logarithmically enhanced at threshold, or that are constant. We also consider a set of corrections that are suppressed near threshold. Our numerical estimates show modest changes of the cross section by the approximate N3LO terms, suggesting a very good perturbative stability of the SIDIS process.Fil: Abele, Maurizio. Eberhard Karls Universität Tübingen; AlemaniaFil: de Florian, Daniel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Físicas. - Universidad Nacional de San Martín. Instituto de Ciencias Físicas; ArgentinaFil: Vogelsang, Werner. Eberhard Karls Universität Tübingen; Alemani

Approximate NNLO QCD corrections to semi-inclusive DIS

We determine approximate next-to-next-to-leading order (NNLO) corrections to unpolarized and polarized semi-inclusive deep-inelastic scattering. They are derived using the threshold resummation formalism, which we fully develop to next-to-next-to-leading logarithmic accuracy, including the two-loop hard factor. The approximate NNLO terms are obtained by expansion of the resummed expression. They include all terms in Mellin space that are logarithmically enhanced at threshold, or that are constant. In terms of the customary semi-inclusive deep-inelastic scattering variables x and zthey include all double distributions (that is, ?plus? distributions and δ functions) in the partonic variables. We also investigate corrections that are suppressed at threshold and we determine the dominant terms among these. Our numerical estimates suggest much significance of the approximate NNLO terms, along with a reduction in scale dependence.Fil: Abele, Maurizio. Eberhard Karls Universität Tübingen; AlemaniaFil: de Florian, Daniel Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; ArgentinaFil: Vogelsang, Werner. Eberhard Karls Universität Tübingen; Alemani

The pp-Daugavet property for function spaces

A natural extension of the Daugavet property for $p$-convex Banach function spaces and related classes is analysed. As an application, we extend the arguments given in the setting of the Daugavet property to show that no reflexive space falls into this class

Approximation of integration maps of vector measures and limit representations of Banach function spaces

[EN] We study whether or not the integration maps of vector measures can be computed as pointwise limits of their finite rank Radon¿Nikodým derivatives. The positive cases are obtained by using the circle of ideas related to the approximation property for Banach spaces. The negative ones are given by means of an appropriate use of the Daugavet property. As an application, we analyse when the norm in a space L 1 (m) of integrable functions can be computed as a limit of the norms of the spaces of integrable functions with respect to the Radon¿Nikodým derivatives of m.E. Jiménez Fernández was supported by Junta de Andalucía and FEDER (grant no. P09-FQM-4911 (Spain)) and by Ministerio de Economía, Industria y Competitividad (grant no. MTM2012-36740-C02- 02 (Spain)). E. A. Sánchez Pérez was supported by Ministerio de Economía, Industria y Competitividad (grant no. MTM2016-77054-C2-1-P (Spain)).Jiménez Fernández, E.; Sánchez Pérez, EA.; Werner, D. (2017). Approximation of integration maps of vector measures and limit representations of Banach function spaces. Annales Polonici Mathematici. 120(1):63-81. https://doi.org/10.4064/ap170407-21-9S6381120

Bottom-up control of sardine and anchovy population cycles in the canary current: insights from an end-to-end model simulation

Sardine and anchovy can exhibit dramatic decadal-scale shifts in abundance in response to climate variability. Sharpe declines of these populations entail particularly serious commercial and ecological consequences in eastern boundary current ecosystems, where they sustain major world fisheries and provide the forage for a broad variety of predators. Understanding the mechanisms and environmental forcing that drive the observed fish variability remains a challenging problem. The modelling study presented here provides an approach that bridges a comprehensive database with an end-to-end modelling framework enabling the investigation of the sources of variability of sardine and anchovy in the Canary Current System. Different biological traits and behaviour prescribed for sardine and anchovy gave rise to different distribution and displacements of the populations, but to a rather synchronous variability in terms of abundance and biomass, in qualitative agreement with historical landing records. Analysis of years with anomalously high increase and decline of the adult population points to food availability (instead of temperature or other environmental drivers) as the main environmental factor determining recruitment for both sardine (via spawning and survival of feeding age-0 individuals) and anchovy (via survival of feeding age-0). Consistent with this, the two species thrive under enhanced upwelling-favourable winds, but only up to some threshold of the wind velocity beyond which larval drift mortality exceeds the positive effect of the extra food supply. Based on the analysis of the simulation, we found that anchovy larvae are particularly vulnerable to enhanced wind-driven advection, and as such do better with more moderate upwelling than sardines.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Population distribution and biomass variability of sardine and anchovy in the Canary current system as simulated by an end-to-end coupled model

Small pelagic fishes as sardine and anchovy account for as much as 20-25% of the world fisheries catch. They are particularly abundant in the four major eastern boundary upwelling ecosystems, where high levels of biological productivity are sustained by the supply of nutrient-rich water from beneath the photic zone. An intrinsic and puzzling feature of small pelagic fish is the large fluctuations of their population, typically occurring at decadal scales. The causes for such fluctuations have been extensively analyzed and discussed in the literature, yet our understanding of the mechanism involved is very limited. End-to-end models are emerging tools useful to test hypothesis for such fish population variability or to gain new insights into the problem. This comprehensive and complex model approach is now becoming possible largely thanks to the present-day computer power. This contribution focuses on the population dynamics of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Canary Current Upwelling Ecosystem. We describe and present the results of an end-to-end coupled model simulation including these two small pelagic species. The end-to-end application includes three model components: the ROMS circulation sub-model, the lower trophic ecosystem sub-model NEMURO, and a recently developed individual-based model for the fish (Rose et al. 2015; Fiechter et al. 2015). The computational grid for the three models covers NW Africa and the Western Iberian Peninsula at a spatial resolution of 12 km. This resolution is sufficient for certain eddy variability to occur in ROMS. Different biological traits were prescribed for anchovy and sardine: temperature optimum, diet preferences, and the onset and duration of the spawning season, among others. A hind-cast simulation of the period 1958-2007 was carried out. Model results reveal a fairly different behavior of sardine and anchovy. Anchovies gather off the northern part of Morocco and the Gulf of Cadiz, whereas sardines appear more scattered across the domain, further offshore, and further south, where upwelling favorable conditions take place year round. Both species exhibit decadal-scale fluctuations in both the location of the center of mass of the population and their biomass abundance; the latter being reasonably correlated with historical landing records.Universidad de Málaga. Campus de Excelencia Internacional del Mar CEIMAR. Campus de Excelencia Andalucía Tec

Dynamics of anchovy and sardine populations in the Canary Current off NW Africa: responses to environmental and climate forcing in a climate-to-fish ecosystem model.

Política de acceso abierto tomada de: https://v2.sherpa.ac.uk/id/publication/13942A 50-year-long (1958–2008) historical simulation of a climate-to-fish ecosystem model for anchovy (Eugralis encrasicolus) and sardine (Sardina pilchardus) populations in the upwelling ecosystem off NW Africa is revisited and analyzed. Anchovy and sardine annual adult abundances were correlated at interannual and decadal time scales in the historical run. A three-step analysis method applied unraveled the environmental and life stage-specific drivers underlying the bottom-up mechanisms responsible for the simulated variability in anchovy and sardine populations. Changes in anchovy adult abundance were primarily controlled by larval survival, prey availability, and local upwelling strength, whereas sardine adult abundance was controlled by age-1 growth affecting age-2 fecundity and egg production via prey availability. Despite different diet preferences, the common sensitivity of anchovy and sardine to prey availability had a synchronizing effect on the two populations, with both anchovy and sardine doing better during years of higher plankton biomass and colder ocean temperatures. Analysis of potential links with modes of climate variability showed that anchovy dynamics were more tightly connected to the AMO while sardine dynamics were correlated to the NAO. This difference stemmed from the vulnerability of the anchovy population to enhanced coastal upwelling causing increased larval drift mortality. Finally, based on an earlier, similar modeling study for the Californian anchovy and Pacific sardine, we argue that the relatively warmer habitat off NW Africa compared to the coastal region off central California is a key feature explaining synchronous populations in the Canary Current versus out-of-phase anchovy and sardine cycles in the California Current