A subsystem-independent generalization of entanglement

We introduce a generalization of entanglement based on the idea that entanglement is relative to a distinguished subspace of observables rather than a distinguished subsystem decomposition. A pure quantum state is entangled relative to such a subspace if its expectations are a proper mixture of those of other states. Many information-theoretic aspects of entanglement can be extended to the general setting, suggesting new ways of measuring and classifying entanglement in multipartite systems. By going beyond the distinguishable-subsystem framework, generalized entanglement also provides novel tools for probing quantum correlations in interacting many-body systems.Comment: 5 pages, 1 encapsulated color figure, REVTeX4 styl

The 't Hooft Model As A Hologram

We consider the 3d dual of 1+1 dimensional large-N_c QCD with quarks in the fundamental representation, also known as the 't Hooft model. 't Hooft solved this model by deriving a Schroedinger equation for the wavefunction of a parton inside the meson. In the scale-invariant limit, we show how this equation is related by a transform to the equation of motion for a scalar field in AdS_3. We thus find an explicit map between the `parton-x' variable and the radial coordinate of AdS_3. This direct map allows us to check the AdS/CFT prescription from the 2d side. We describe various features of the dual in the conformal limit and to the leading order in conformal symmetry breaking, and make some comments on the 3d theory in the fully non-conformal regime.Comment: Introduction expanded. References rearranged. The version published in JHE

Tensors Mesons in AdS/QCD

We explore tensor mesons in AdS/QCD focusing on f2 (1270), the lightest spin-two resonance in QCD. We find that the f2 mass and the partial width for f2 -> gamma gamma are in very good agreement with data. In fact, the dimensionless ratio of these two quantities comes out within the current experimental bound. The result for this ratio depends only on Nc and Nf, and the quark and glueball content of the operator responsible for the f2; more importantly, it does not depend on chiral symmetry breaking and so is both independent of much of the arbitrariness of AdS/QCD and completely out of reach of chiral perturbation theory. For comparison, we also explore f2 -> pi pi, which because of its sensitivity to the UV corrections has much more uncertainty. We also calculate the masses of the higher spin resonances on the Regge trajectory of the f2, and find they compare favorably with experiment.Comment: 21 pages, 1 figure; Li's correcte

A Non-Renormalization Theorem for the d=1, N=8 Vector Multiplet

Sigma models describing low energy effective actions on D0-brane probes with N=8 supercharges are studied in detail using a manifestly d=1, N=4 super-space formalism. Two 0+1 dimensional N=4 multiplets together with their general actions are constructed. We derive the condition for these actions to be N=8 supersymmetric and apply these techniques to various D-brane configurations. We find that if in addition to N=8 supersymmetry the action must also have Spin(5) invariance, the form of the sigma model metric is uniquely determined by the one-loop result and is not renormalized perturbatively or non-perturbatively.Comment: Uses harvmac, 16 pages. We correct an error pointed out by E. Witte

UN Ocean Conference needs transparent and science-based leadership on ocean conservation

The United Nations Ocean conference convened in June 2022. Heads of state, businesses, and civil society organizations met in Lisbon to discuss how to scale up ocean action to achieve SDG 14 goals. In the face of the existential challenges of the climate emergency and species extinction crisis, bold and decisive action on ocean conservation through a shift in the protection paradigm is needed now. Recognizing existing barriers (e.g., political, organizational, social, economic) that operate at various scales (e.g., international, regional and national) and that are precluding achieving a healthy ocean is key and has to be addressed with strong leadership and sound commitments. A roadmap with clear steps and achievements including metrics assessing protection levels, stages of establishment, management effectiveness and equity is now needed to guarantee the success of marine conservation goals. Portugal can and should help lead the way by adopting such a roadmap and approach, but post-2020 decisions need to incorporate, beyond area goals, both the quality and effectiveness of ocean protection through metrics and standards such as those provided by the MPA Guide, Green List and Blue Parks.Fundação para a Ciência e a Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio

A regulation-based classification system for marine protected areas: A response to Dudley et al. [9]

Dudley et al. [9] commented on our paper [11], arguing that the current IUCN objective-based categorization of protected areas, which is also used in marine protected areas (MPAs), should not be abandoned and replaced by the new regulation-based classification system [11]. Here we clarify that we do not advocate replacing the current IUCN categories, but highlight the benefits of using both the objective-based IUCN categories and the new regulation-based classification when applied to MPAs. With an increasing number of MPA types being implemented, most of them multiple-use areas zoned for various purposes, assessing ecological and socio-economic benefits is key for advancing conservation targets and policy objectives. Although the IUCN categories can be used both in terrestrial and marine systems, they were not designed to follow a gradient of impacts and there is often a mismatch between stated objectives and implemented regulations. The new regulation-based classification system addresses these problems by linking impacts of activities in marine systems with MPA and zone classes in a simple and globally applicable way. Applying both the IUCN categories and the regulation based classes will increase transparency when assessing marine conservation goals.ERA-Net BiodivERsA project "BUFFER Partially protected areas as buffers to increase the linked social ecological resilience"; national funders ANR (France); FCT (Portugal); FOR-MAS (Sweden); SEPA (Sweden); RCN (Norway); project BUFFER; Fernand Braudel IFER fellowship (Fondation Maison des Sciences de l'Homme); Fundacao para a Ciencia e a Tecnologia (FCT) [UID/MAR/04292/2013

Decadal-Scale Vegetation Change Driven by Salinity at Leading Edge of Rising Sea Level

As sea levels rise, low-lying coastal forests increasingly are subject to stressors such as inundation and saltwater exposure. At long timescales (for example, centuries), the extent of inundation and saltwater exposure will increase; however, on a decadal timescale, the role of these drivers may differ in both magnitude and direction. To investigate the drivers of decadal-scale vegetation change, we measured the changes in five metrics of vegetation composition and structure between 2003/2004 and 2016/ 2017 at 98 plots distributed across a vegetation gradient from coastal forest to brackish marshes (< 0.518 ppt). We used elevation as a proxy of inundation vulnerability and soil sodium concentration as a proxy of saltwater exposure, and we investigated relationships between these two variables and the change in vegetation conditions between the two sampling periods. Soil sodium concentration was a significant predictor of vegetation change for all five vegetation metrics, whereas the effect of elevation was not significant for any of the metrics. The one site that was affected by wildfire twice during the duration of the study shifted almost completely from forest to marsh with limited regeneration ofwoody vegetation observed in 2016/ 2017. Our results show that salinization in our system is a more important driver of vegetation change than inundation potential. Furthermore, the effects of drought-induced salinization could be amplified by the elevated risk of wildfire during droughts. Forecasting the response of coastal wetlands to rising sea levels will require a better understanding of the individual and combined effects of salinity, droughts, and wildfires on vegetation

An analysis of long-term relationships among count statistics and metrics of synthetic tropical cyclones downscaled from CMIP5 models

In a changing climate, the impact of tropical cyclones on the United States Atlantic and Gulf Coasts will be affected both by how intense and how frequent these storms become. The observational record of tropical cyclones in the Atlantic Basin is too short (A.D. 1851 to present) to allow for accurate assessment of low-frequency variability in storm activity. In order to overcome the limitations of the short observational record, we downscale four Coupled Model Intercomparison Project Phase 5 models to generate synthetic tropical cyclone data sets for the Atlantic Basin that span the interval of A.D. 850–2005. Using these long-term synthetic tropical cyclone data sets, we investigate the relationship between power dissipation and ocean temperature metrics, as well as the relationship between basin-wide and landfalling tropical cyclone count statistics over the past millennium. Contrary to previous studies, we find only a very weak relationship between power dissipation and main development region sea surface temperature in the Atlantic Basin. Consistent with previous studies, we find that basin-wide and landfalling tropical cyclone counts are significantly correlated with one another, lending further support for the use of paleohurricane landfall records to infer long-term basin-wide tropical cyclone trends.United States. National Oceanic and Atmospheric Administration (grant 424-18 45GZ

Vector sensor geoacoustic estimation with standard arrays

Vector Sensor Arrays (hereafter VSAs) are progressively becoming more and more attractive among the underwater acoustics community due to the advantages of VSAs over standard arrays of acoustic hydrophones. While the later record only acoustic pressure, VSAs record also particle velocity; such technical feature increases by a factor of four the amount of information that can be used for the processing ofacoustic data, leading to a substantial increase in performance. Since VSA sensor technology is relatively recent, and thus not yet fully available, one can consider the usage of closely located pairs of standard hydrophones, which can be used to estimate the vertical component of particle velocity as a difference of acoustic pressure, measured at each pair of hydrophones. The present discussion introduces a theoretical review of particle velocity calculations using different acoustic models, and tests the performance of estimators for geoacoustic inversion using acoustic pressure, particle velocity components and direct and approximated values of the vertical component only.This work was funded by National Funds through FCT - Foundation for Science and Technology under project SENSOCEAN (PTDC/EEA-ELC/104561/2008)