Spatial antibunching of photons with parametric down-conversion

The theoretical framework behind a recent experiment by Nogueira et. al. [Phys. Rev. Lett. 86}, 4009 (2001)] of spatial antibunching in a two-photon state generated by collinear type II parametric down-conversion and a birefringent double-slit is presented. The fourth-order quantum correlation function is evaluated and shown to violate the classical Schwarz-type inequality, ensuring that the field does not have a classical analog. We expect these results to be useful in the rapidly growing fields of quantum imaging and quantum information.Comment: 5 pages, 3 figures. Minor changes made, accepted for publication in PR

Influence of production variables and starting material on charcoal stable isotopic and molecular characteristics

We present a systematic study on the effect of starting species, gas composition, temperature, particle size and duration of heating upon the molecular and stable isotope composition of high density (mangrove) and low density (pine) wood. In both pine and mangrove, charcoal was depleted in o13C relative to the starting wood by up to 1.6% and 0.8%, respectively. This is attributed predominantly to the progressive loss of isotopically heavier polysaccharides, and kinetic effects of aromatization during heating. However, the pattern of o13C change was dependant upon both starting species and atmosphere, with different structural changes associated with charcoal production from each wood type elucidated by Solid-State o13C Nuclear Magnetic Resonance Spectroscopy. These are particularly evident at lower temperatures, where variation in the oxygen content of the production atmosphere results in differences in the thermal degradation of cellulose and lignin. It is concluded that production of charcoal from separate species in identical conditions, or from a single sample exposed to different production variables, can result in significantly different o13C of the resulting material, relative to the initial wood. These results have implications for the use of charcoal isotope composition to infer past environmental change

HABs in coastal upwelling systems: Insights from an exceptional red tide of the toxigenic dinoflagellate Alexandrium minutum

Alexandrium minutum blooms generally occur in semi-enclosed sites such as estuaries, harbours and lagoons, where enhanced stratification, restricted circulation and accumulation of resting cysts in the sediment set suitable habitat conditions for the proliferation of this paralytic shellfish poisoning toxigenic species. In the Galician Rías Baixas (NW Iberian Peninsula), according to weekly time-series between 1994 and 2020, blooms of A. minutum were recurrent in small, shallow estuarine bays inside the Rías de Vigo and Pontevedra, but rarely detected, and if so at low concentrations, out of these environments. However, from May to July 2018 it developed as usual in the small inner bays but then spread over both Rías (Vigo and Pontevedra) causing discoloured waters during one month and prolonged harvesting closures. Meteorological conditions during that period (rains / runoff higher than climatological averages, sustained temperature increment and oscillating wind pattern –i.e., series of upwelling-relaxation cycles), fostered optimal circumstances for the development of that extensive and massive proliferation: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset and development inside a small inner bay; transport within the surface layer, from these sites towards the interior parts of the Ría; and dispersion all over the embayment. Seedbeds with high concentrations of resting cysts were detected several months after the bloom, which may have favoured flourishment of A. minutum in the following two years, markedly in 2020. The present work contributes to the general understanding of the dynamics of harmful algal blooms (HABs), from which surveillance indicators of the state of marine ecosystems and their evolution can be derived. We hypothesize that the intensity and frequency of A. minutum proliferations in the Galician Rías could increase under projected climate trends.Postprint2,69

Bloom dynamics of an exceptional red tide of the toxigenic dinoflagellate

The toxic dinoflagellate Alexandrium minutum generally proliferates in semi-enclosed sites such as estuaries, harbours and lagoons, where stratification, restricted circulation and accumulation of resting cysts set suitable conditions for its development. In the Galician Rías (NW Iberian Peninsula), its blooms follow also this pattern. They are recurrent in small, shallow estuarine bays inside the Rías, but rarely detected, and if so in minor amount, out of these areas. However, a massive proliferation of A. minutum from June to July 2018 in the Rías Baixas (Vigo and Pontevedra) changed this picture. The bloom initiated in semi-enclosed waters, as previously described for this species, but thereafter spread to the whole embayments where persisted more than one month. It generated a noticeable red tide with disperse patches that became heavily concentrated inside the port of Vigo. During that period shellfish harvesting closures and paralytic shellfish toxins in certain marine invertebrates and fish were reported for the first time in Spain. Meteorological conditions (higher than usual rains/runoff, sustained temperature increment and oscillating wind pattern promoting a series of upwelling-relaxation cycles) fostered optimal circumstances for the outbreak of A. minutum: strong vertical stratification and the alternation of retention and dispersion processes. Simulations from a particle tracking model portrayed the observed bloom development phases: onset, transport within the surface layer towards the interior parts of the Ría of Vigo, and dispersion all over the embayment. High concentrations of resting cysts were detected several months after the bloom, which may have favoured flourish of A. minutum in the following years, markedly in 2020

Análise da estrutura fatorial da versão em português da Escala de Auto-Silenciamento

This study focuses on the adaptation of the Portuguese version of the Escala de Autosilenciamiento [EAS, for its Portuguese acronym] (Neves, 2005) that has been designed to assess the use of cognitive schemas for self silencing in intimate relationships. Participants were 371 women with a mean age of 22.36 years (SD=2.69; Min=18; Max=31), who at that time were involved in affective relationships with an average duration of 39.65 months (SD=33.93; Min=10; Max=192).The exploratory factor analysis suggests a factor solution of three factors, where the first factor includes items from the silencing of the sef and divided self subscales. The second factor includes items from the care-giving subscale such as self-sacrifice. And the third factor includes items from the externalized self-perception subscale. Results of the confirmatory factor analysis show reliable global indices of fitness of the model, confirming the quality of the model in terms of adjustment to empirical data (X2/df=1.964, CFI=.862, GFI=.894, RMSEA=.051) compared to the original model. Implications for a further study of the construct validity of the scale are discussed.Este estudo se centra na adaptação da versão em português da Escala de Auto-silenciamento (EAS; Neves, 2005) que está desenhada para avaliar o uso de esquemas cognitivos de auto-silenciamento nas relações íntimas. Neste estudo participaram 371 mulheres, com uma idade média de 22,36 anos (DP = 2,69, mín. = 18, máx. = 31), que nessa época estavam envolvidas em relações afetivas com uma duração média de 39,65 meses. (DP = 33,93, mín. = 0,10; máx. = 192). Uma análise fatorial exploratória posterior sugere uma solução de três fatores, aonde o primeiro fator inclui os itens da sub-escala de silenciamento do self e do self dividido; o segundo inclui os itens da sub-escala de Provisão de cuidados como o auto sacrifício, e o terceiro inclui os itens da sub-escala de auto percepção externalizada. Os resultados da análise fatorial confirmatória mostram índices gerais de adequação confiáveis, o que confirma a qualidade do ajuste do modelo aos dados empíricos (X2/df = 1964, CFI = .862, GFI = 0,894, RMSEA = 0,051) em comparação com a teste original. Analisam-se as implicações para um estudo más profundo da validez de constructo da escala.Este estudio se centra en la adaptación de la versión en portugués de la Escala de Autosilenciamiento (EAS; Neves, 2005) que está diseñada para evaluar el uso de esquemas cognitivos de autosilenciamiento en las relaciones íntimas. En este estudio participaron 371 mujeres, con una edad media de 22,36 años (DP = 2,69, mín. = 18, máx. = 31), que en esa época estaban involucradas en relaciones afectivas con una duración promedio de 39,65 meses. (DP = 33,93, mín. = 0,10; máx. = 192). Un análisis factorial exploratorio posterior sugiere una solución de tres factores, donde el primer factor incluye los ítems de la subescala de silenciamiento del self y del self dividido; el segundo incluye los ítems de la subescala de Provisión de cuidados como el autosacrificio, y el tercero incluye los ítems de la subescala de autopercepción externalizada. Los resultados del análisis factorial confirmatorio muestran índices generales de adecuación fiables, lo que confirma la calidad del ajuste del modelo a los datos empíricos (X2/df = 1964, CFI = .862, GFI = 0,894, RMSEA = 0,051) en comparación con la prueba original. Se analizan las implicaciones para un estudio más profundo de la validez de constructo de la escala

Biochemical profile and in vitro neuroprotective properties of Carpobrotus edulis L., a medicinal and edible halophyte native to the coast of South Africa

This work reports the nutritional profile and in vitro neuroprotective properties of leaves of Carpobrotus edulis L, a medicinal and edible succulent species native to the coast of South Africa. Biomass was evaluated for proximate composition and for contents in carotenoids, liposoluble pigments and minerals. Hexane, dichloromethane, ethyl acetate and methanol extracts were prepared by Soxhlet extraction from dried biomass and evaluated for in vitro inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), capacity to attenuate hydrogen peroxide (H2O2)-induced injury in the human dopaminergic cell line SH-SY5Y and for anti-neuroinflammatory potential on lipopolysaccharide (LPS)-stimulated microglia cells. Extracts were evaluated for antioxidant activity by four complementary methods, total content of phenolics, tannins and flavonoids. Finally the profile of the main phenolic compounds was determined by high performance liquid chromatography with diode array detection (HPLC-DAD). C edulis has a high moisture content, high levels of crude protein, fibre, ash, carotenoids, calcium and iron and a low fat level. The extracts were able to efficiently scavenge the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), reduce iron and chelate copper and iron ions, and exhibited different levels of phenolic compounds in the order ethyl acetate > methanol > dichloromethane > hexane. The main compounds detected were gallic and salicylic acids and quercetin, all in the ethyl acetate extract. The extracts allowed a dual and potent inhibition of AChE and BuChE. The dichloromethane and methanol extracts had the strongest capacity to prevent cell death induced by H2O2, and the methanol extract had anti-neuronflammatory properties. All together our results suggest that consumption of leaves of C edulis can contribute for a balanced diet, and that they may add to the improvement of cognitive functions. It also suggests possible novel biotechnological applications of C. edulis such as source of molecules and/or products for the food and/or pharmaceutical industries. Studies aiming to the isolation and identification of the bioactive compounds are already in progress. (C) 2017 SAAB. Published by Elsevier B.V. All rights reserved.Portuguese National BudgetXtremeGourmet project [ALG-01-0247-FEDER-017676]FCT Investigator Programme [IF/00049/2012]info:eu-repo/semantics/publishedVersio