Major shifts at the range edge of marine forests: the combined effects of climate changes and limited dispersal

Global climate change is likely to constrain low latitude range edges across many taxa and habitats. Such is the case for NE Atlantic marine macroalgal forests, important ecosystems whose main structuring species is the annual kelp Saccorhiza polyschides. We coupled ecological niche modelling with simulations of potential dispersal and delayed development stages to infer the major forces shaping range edges and to predict their dynamics. Models indicated that the southern limit is set by high winter temperatures above the physiological tolerance of overwintering microscopic stages and reduced upwelling during recruitment. The best range predictions were achieved assuming low spatial dispersal (5 km) and delayed stages up to two years (temporal dispersal). Reconstructing distributions through time indicated losses of similar to 30% from 1986 to 2014, restricting S. polyschides to upwelling regions at the southern edge. Future predictions further restrict populations to a unique refugium in northwestern Iberia. Losses were dependent on the emissions scenario, with the most drastic one shifting similar to 38% of the current distribution by 2100. Such distributional changes might not be rescued by dispersal in space or time (as shown for the recent past) and are expected to drive major biodiversity loss and changes in ecosystem functioning.Electricity of Portugal (Fundo EDP para a Biodiversidade); FCT - Portuguese Science Foundation [PTDC/MAR-EST/6053/2014, EXTANT-EXCL/AAG-GLO/0661/2012, SFRH/BPD/111003/2015

Optical-force laws for guided light in linear media

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORThe mechanical response of transparent materials to optical forces is a topic that concerns a wide range of fields, from the manipulation of biological material by optical tweezers to the design of nano-optomechanical systems. However, the fundamental aspects of such forces have always been surrounded by controversies, and several different formulations have been proposed. In this paper, we propose a general stress tensor formalism to put all optical forces in a consistent presentation that allows us to study how different predictions emerge, and use the specific case of light propagating as a superposition of guided modes in lossless dielectric waveguides as a physical example. We use this formalism to calculate optical forces for straight and curved waveguide sections and all possible excitation configurations for a given set of coupled eigenmodes, and then compare the results for each of the known proposed optical-force laws in a framework that permits distinguishing where there will be differences between the force laws proposed. The general formalism also allows us to show that proper use of the divergence theorem is crucial to account for all force terms, many of which vanish if the procedure most commonly used is applied for situations other than eigenmodes in straight waveguides in vacuum. Finally, it is known that discrepancies in the predicted forces arise from the incompleteness of each stress tensor with respect to the total-energy-momentum tensor of the system. A better understanding of how different stress tensors predict very different forces for certain waveguide geometries should open a pathway to identifying how to properly assemble the full tensor, as well as for experimental tests to confirm the predictions.100117CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORSem informaçãoSem informaçãoSem informaçã

Optical force laws for guided light in linear media

The mechanical response of transparent materials to optical forces is a topic that concerns a wide range of fields, from the manipulation of biological material by optical tweezers to the design of nano-optomechanical systems (NOMS). However, the fundamental aspects of such forces have always been surrounded by controversies, and several different formulations have been proposed. In this work, we focus on the specific case of light propagating as a superposition of guided modes in lossless dielectric waveguides as a physical example upon which to build a general stress tensor. We use this formalism to calculate optical forces for straight and curved waveguide sections and all possible excitation configurations for a given set of coupled eigenmodes, and then compare the results for each of the known proposed optical force laws as well as a novel one derived from this general stress tensor. We show that proper use of the divergence theorem is crucial to account for all force terms, many of which vanish if the procedure most commonly used is applied for situations other than eigenmodes in straight waveguides. A better understanding of how different stress tensors predict very different forces for certain waveguide geometries opens a pathway for new experimental tests of each formulation.Comment: 14 pages, 3 figure

Genetic improvement of forest tree species.

Brazilian forestry sector is considered one of the most developed in the world, being the base for important industrial segments which use wood as raw material. Tree breeding has played an important role on improving the competitiveness of Brazilian forestry-based companies, especially for its positive reflexes on increasing adaptation, forestry productivity and wood quality. In spite of the importance of other forest trees for the economy, such as Schizolobium, Araucaria, Populus and Hevea, the main genera under genetic improvement in the country are Eucalyptus, Pinus, Acacia and Tectona. They are used by industries like pulp and paper, siderurgy, tannin, chips for exportation and lumber, constituting an important source of revenues for the Brazilian?s economy, besides their positive social and environmental impacts. This paper presents a generic approach to genetic improvement aspects of these four major genera currently undergoing breeding in Brazil.Especial issue

Seleção recorrente recíproca entre populações sintéticas multi-espécies (SRR-PSME) de eucalipto.

Propõe-se estratégia de melhoramento para o eucalipto, que visa contemplar, em um mesmo indivíduo, características desejáveis presentes em diferentes espécies e, simultaneamente, capitalizar heterose para crescimento, advinda de vários pares de espécies, cujas combinações são sabidamente heteróticas. Baseia-se na obtenção de duas populações sintéticas multi-espécies e posterior seleção recorrente recíproca (SRR) entre essas. É denominada seleção recorrente recíproca entre populações sintéticas multi-espécies (SRR-PSME) e melhora os caracteres resistência à seca e às doenças, volume, densidade, rendimento e teor de lignina. São apresentadas opções para composição das populações sintéticas. A SRR-PSME é favorável também à aplicação da seleção genômica.Nota Científica

Experimental Observation of Quantum Correlations in Modular Variables

We experimentally detect entanglement in modular position and momentum variables of photon pairs which have passed through $D$-slit apertures. We first employ an entanglement criteria recently proposed in [Phys. Rev. Lett. {\bf 106}, 210501 (2011)], using variances of the modular variables. We then propose an entanglement witness for modular variables based on the Shannon entropy, and test it experimentally. Finally, we derive criteria for Einstein-Podolsky-Rosen-Steering correlations using variances and entropy functions. In both cases, the entropic criteria are more successful at identifying quantum correlations in our data.Comment: 7 pages, 4 figures, comments welcom