934 research outputs found
On Hirschman and log-Sobolev inequalities in mu-deformed Segal-Bargmann analysis
We consider a deformation of Segal-Bargmann space and its transform. We study
L^p properties of this transform and obtain entropy-entropy inequalities
(Hirschman) and entropy-energy inequalities (log-Sobolev) that generalize the
corresponding known results in the undeformed theory.Comment: 42 pages, 3 figure
Shift-Symmetric Configurations in Two-Dimensional Cellular Automata: Irreversibility, Insolvability, and Enumeration
The search for symmetry as an unusual yet profoundly appealing phenomenon,
and the origin of regular, repeating configuration patterns have long been a
central focus of complexity science and physics. To better grasp and understand
symmetry of configurations in decentralized toroidal architectures, we employ
group-theoretic methods, which allow us to identify and enumerate these inputs,
and argue about irreversible system behaviors with undesired effects on many
computational problems. The concept of so-called configuration shift-symmetry
is applied to two-dimensional cellular automata as an ideal model of
computation. Regardless of the transition function, the results show the
universal insolvability of crucial distributed tasks, such as leader election,
pattern recognition, hashing, and encryption. By using compact enumeration
formulas and bounding the number of shift-symmetric configurations for a given
lattice size, we efficiently calculate the probability of a configuration being
shift-symmetric for a uniform or density-uniform distribution. Further, we
devise an algorithm detecting the presence of shift-symmetry in a
configuration.
Given the resource constraints, the enumeration and probability formulas can
directly help to lower the minimal expected error and provide recommendations
for system's size and initialization. Besides cellular automata, the
shift-symmetry analysis can be used to study the non-linear behavior in various
synchronous rule-based systems that include inference engines, Boolean
networks, neural networks, and systolic arrays.Comment: 22 pages, 9 figures, 2 appendice
Small-scale fisheries access to fishing opportunities in the European Union: is the common fisheries policy the right step to SDG14b?
The profile of small-scale fisheries has been raised through a dedicated target within the United Nations Sustainable Development Goals (SDG14b) that calls for the provision of âaccess of small-scale artisanal fishers to marine resources and marketsâ. By focusing on access to fisheries resources in the context of European Union, in this article we demonstrate that the potential for small-scale fishing sectors to benefit from fishing opportunities remains low due to different mechanisms at play including legislative gaps in the Common Fisheries Policy, and long-existing local structures somewhat favouring the status quo of distributive injustice. Consequently, those without access to capital and authority are faced by marginalizing allocation systems, impacting the overall resilience of fishing communities. Achieving SDG14b requires an overhaul in the promulgation of policies emanating from the present nested governance systems.info:eu-repo/semantics/publishedVersio
Persistent gender bias in marine science and conservation calls for action to achieve equity
The increasing consideration of gender balance in conservation science and practice has been reflected in the setting of global commitments. Yet, women remain under-represented in science and conservation decision-making. We compiled and analyzed data on the representation of women in hiring, publishing, funding, and leadership positions in European Union marine sciences and conservation. To explore scientists' perceptions of gender imbalance in marine sciences and conservation more broadly, we conducted a global survey and analyzed 764 questionnaires from 42 countries. Participants were also asked to identify measures that promote gender equity. We found a consistent pattern of women being under-representated across institutions and nations characterized by a relatively balanced representation of men and women in early career stages and a growing gap in later stages, with women occupying only 13% to 24% of senior positions. The same pattern was found in publishing, funding, and leadership of research institutes. Survey results demonstrate that most marine scientists are aware of the general and persistent gender bias, and perceive that it may compromise our ability to effectively solve conservation problems. Measures that increase fairness in evaluations (e.g. for hiring) and that support work-life balance ranked high, whereas gender-oriented measures, such as gender-specific scholarships, received less support. Our findings suggest that mechanisms promoting a fairer share of family responsibilities and transparent processes in hiring and evaluation are the most promising path to a more balanced participation of women in scientific leadership and conservation decision-making. Such measures may benefit not only women but diversity more generally
Effects of drought ? altered seasonality and low rainfall ? in net ecosystem carbon exchange of three contrasting Mediterranean ecosystems
International audienceDroughts cause reductions in gross primary production (GPP) and also in net ecosystem exchange (NEE), contributing to most of the inter-annual variability in terrestrial carbon sequestration. In seasonally dry climates (Mediterranean) droughts result from reductions in annual rainfall and from changes in rain seasonality. In western Iberia, the hydrological-year (i.e., from October to September) of 2004?2005 was extremely dry, with precipitation 50% below the long-term mean (691 mm in 1961?1990), but 2005?2006 was normal. We compared the carbon fluxes measured by the eddy covariance technique from three contrasting ecosystems in southern Portugal: an evergreen oak woodland (savannah-like) with ca. 21% tree cover; a Mediterranean C3/C4 grassland; and a coppiced eucalyptus plantation. During the dry hydrological-year of 2004?2005, NEE was lowest, the highest sink strength was in the eucalypt plantation (NEE = ?399 g C m ?2 year?1) as compared to the oak woodland (NEE = ?88 g C m ?2 year?1), and the grassland (NEE = +49 g C m ?2 year ?1). The latter was a source of carbon dioxide. The NEE values of the dry year were, however, much lower than those for wetter years, e.g. NEE = ?861 g C m?2 year ?1 in 2002?2003 in the eucalypt plantation. The NEE of the grassland and the oak savannah in the 2005?2006 hydrological-year, with annual precipitation above the long term mean, were ?190 and ?120 g C m ?2 year?1, respectively. All ecosystems studied increased their rain-use efficiency (GPP per unit of rain volume) increased in dry years. In the case of annual vegetation ? grassland and low tree density woodland, however &ndash, rain-use efficiency decreased with severe drought. However, this was more pronounced in the eucalypt plantation due to greater GPP and the use of deep soil water resources. Although both calendar years of 2004 and 2005 had equally low rainfall, the effect of drought on the eucalypt plantation was delayed until the second dry year. This suggests that the effects of water deficits on Mediterranean forests are exacerbated by prolonged droughts when long-term soil water reserves are depleted. The grassland, however, was more vulnerable and responded faster to water deficits. This effect of drought was less pronounced in the oak woodland due to the sparse tree cover
Investigation of the 6He cluster structures
The 4He+2n and t+t clustering of the 6He ground state were investigated by
means of the transfer reaction 6He(p,t)4He at 25 MeV/nucleon. The experiment
was performed in inverse kinematics at GANIL with the SPEG spectrometer coupled
to the MUST array. Experimental data for the transfer reaction were analyzed by
a DWBA calculation including the two neutrons and the triton transfer. The
couplings to the 6He --> 4He + 2n breakup channels were taken into account with
a polarization potential deduced from a coupled-discretized-continuum channels
analysis of the 6He+1H elastic scattering measured at the same time. The
influence on the calculations of the 4He+t exit potential and of the triton
sequential transfer is discussed. The final calculation gives a spectroscopic
factor close to one for the 4He+2n configuration as expected. The spectroscopic
factor obtained for the t+t configuration is much smaller than the theoretical
predictions.Comment: 10 pages, 11 figures, accepted in PR
Twelve recommendations for advancing marine conservation in European and contiguous seas
Like most ocean regions today, the European and contiguous seas experience cumulative impacts from local human activities and global pressures. They are largely in poor environmental condition with deteriorating trends. Despite several success stories, European policies for marine conservation fall short of being effective. Acknowledging the challenges for marine conservation, a 4-year multi-national network, MarCons, supported collaborative marine conservation efforts to bridge the gap between science, management and policy, aiming to contribute in reversing present negative trends. By consolidating a large network of more than 100 scientists from 26 countries, and conducting a series of workshops over 4 years (2016â2020), MarCons analyzed challenges, opportunities and obstacles for advancing marine conservation in the European and contiguous seas. Here, we synthesize the major issues that emerged from this analysis and make 12 key recommendations for policy makers, marine managers, and researchers. To increase the effectiveness of marine conservation planning, we recommend (1) designing coherent networks of marine protected areas (MPAs) in the framework of marine spatial planning (MSP) and applying systematic conservation planning principles, including re-evaluation of existing management zones, (2) designing MPA networks within a broader transboundary planning framework, and (3) implementing integrated land-freshwater-sea approaches. To address inadequate or poorly informed management, we recommend (4) developing and implementing adaptive management plans in all sites of the Natura 2000 European conservation network and revising the Natura 2000 framework, (5) embedding and implementing cumulative effects assessments into a risk management process and making them operational, and (6) promoting actions to reach âgood environmental statusâ in all European waters. To account for global change in conservation planning and management, we further recommend (7) developing conservation strategies to address the impacts of global change, for example identifying climate-change refugia as high priority conservation areas, and (8) incorporating biological invasions in conservation plans and prioritizing management actions to control invasive species. Finally, to improve current practices that may compromise the effectiveness of conservation actions, we recommend (9) reinforcing the collection of high-quality open-access data, (10) improving mechanisms for public participation in MPA planning and management, (11) prioritizing conservation goals in full collaboration with stakeholders, and (12) addressing gender inequality in marine sciences and conservation
Net ecosystem carbon exchange in three contrasting Mediterranean ecosystems ? the effect of drought
International audienceDroughts reduce gross primary production (GPP) and ecosystem respiration (Reco), contributing to most of the inter-annual variability in terrestrial carbon sequestration. In seasonally dry climates (Mediterranean), droughts result from reductions in annual rainfall and changes in rain seasonality. We compared carbon fluxes measured by the eddy covariance technique in three contrasting ecosystems in southern Portugal: an evergreen oak woodland (savannah-like) with ca.~21% tree crown cover, a grassland dominated by herbaceous annuals and a coppiced short-rotation eucalyptus plantation. During the experimental period (2003?2006) the eucalyptus plantation was always the strongest sink for carbon: net ecosystem exchange rate (NEE) between ?861 and ?399 g C m?2 year?1. The oak woodland and the grassland were much weaker sinks for carbon: NEE varied in the oak woodland between ?140 and ?28 g C m?2 year?1 and in the grassland between ?190 and +49 g C m?2 year?1. The eucalyptus stand had higher GPP and a lower proportion of GPP spent in respiration than the other systems. The higher GPP resulted from high leaf area duration (LAD), as a surrogate for the photosynthetic photon flux density absorbed by the canopy. The eucalyptus had also higher rain use efficiency (GPP per unit of rain volume) and light use efficiency (the daily GPP per unit incident photosynthetic photon flux density) than the other two ecosystems. The effects of a severe drought could be evaluated during the hydrological-year (i.e., from October to September) of 2004?2005. Between October 2004 and June 2005 the precipitation was only 40% of the long-term average. In 2004?2005 all ecosystems had GPP lower than in wetter years and carbon sequestration was strongly restricted (less negative NEE). The grassland was a net source of carbon dioxide (+49 g C m?2 year?1). In the oak woodland a large proportion of GPP resulted from carbon assimilated by its annual vegetation component, which was strongly affected by the shortage of rain in winter. Overall, severe drought affected more GPP than Reco leading to the deterioration of NEE. Although the rain-use efficiency of the eucalyptus plantation increased in the dry year, this was not the case of evergreen oak woodland, which rain-use efficiency was not influenced by drought. Recovery after drought alleviation, i.e., beginning with heavy rain in October 2005, was fully accomplished in 2006 in the oak woodland and grassland, but slow in the eucalyptus plantation
Progress in Monte Carlo design and optimization of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) will be an instrument covering a wide
energy range in very-high-energy (VHE) gamma rays. CTA will include several
types of telescopes, in order to optimize the performance over the whole energy
range. Both large-scale Monte Carlo (MC) simulations of CTA super-sets
(including many different possible CTA layouts as sub-sets) and smaller-scale
simulations dedicated to individual aspects were carried out and are on-going.
We summarize results of the prior round of large-scale simulations, show where
the design has now evolved beyond the conservative assumptions of the prior
round and present first results from the on-going new round of MC simulations.Comment: 4 pages, 5 figures. In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at
arXiv:1307.223
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