3,987 research outputs found

    Temporal patterns in acoustic presence and foraging activity of oceanic dolphins at seamounts in the Azores

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    © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cascao, I., Lammers, M. O., Prieto, R., Santos, R. S., & Silva, M. A. Temporal patterns in acoustic presence and foraging activity of oceanic dolphins at seamounts in the Azores. Scientific Reports, 10(1), (2020): 3610, doi:10.1038/s41598-020-60441-4.Several seamounts have been identified as hotspots of marine life in the Azores, acting as feeding stations for top predators, including cetaceans. Passive acoustic monitoring is an efficient tool to study temporal variations in the occurrence and behaviour of vocalizing cetacean species. We deployed bottom-moored Ecological Acoustic Recorders (EARs) to investigate the temporal patterns in acoustic presence and foraging activity of oceanic dolphins at two seamounts (Condor and Gigante) in the Azores. Data were collected in March–May 2008 and April 2010–February 2011. Dolphins were present year round and nearly every day at both seamounts. Foraging signals (buzzes and bray calls) were recorded in >87% of the days dolphin were present. There was a strong diel pattern in dolphin acoustic occurrence and behaviour, with higher detections of foraging and echolocation vocalizations during the night and of social signals during daylight hours. Acoustic data demonstrate that small dolphins consistently use Condor and Gigante seamounts to forage at night. These results suggest that these seamounts likely are important feeding areas for dolphins. This study contributes to a better understanding of the feeding ecology of oceanic dolphins and provides new insights into the role of seamount habitats for top predators.This research was supported by the Fundação para a Ciência e a Tecnologia (FCT), Azores 2020 Operational Programme and the Fundo Regional da Ciência e Tecnologia (FRCT), through research projects TRACE (PTDC/MAR/74071/2006), MAPCET (M2.1.2/F/012/2011), FCT-Exploratory (IF/00943/2013/CP1199/CT0001), WATCH IT (Acores-01-0145-FEDER-000057) and MISTIC SEAS II (GA11.0661/2017/750679/SUB/ENV.C2), co-funded by FEDER, COMPETE, QREN, POPH, European Social Fund (ESF), the Portuguese Ministry for Science and Education, and EU-DG/ENV. The Azores 2020 Operational Programme is funded by the community structural funds ERDF and ESF. Funds were also provided by FCT to MARE, through the strategic project UID/MAR/04292/2013. MAS was supported through a FCT Investigator contract funded by POPH, QREN, ESF and the Portuguese Ministry for Science and Education (IF/00943/2013). IC was supported by a FCT doctoral grant (SFRH/BD/41192/2007) and RP by a FCT postdoctoral grant (SFRH/BPD/108007/2015). We thank the field and crew teams for assisting with the many deployments and recoveries of the EARs. Special thanks to Norberto Serpa for helping with mooring design, Ken Sexton and Michael Richlen for their roles in manufacturing the EARs, Sergio Gomes for building the battery packs, and Lisa Munger for adapting Triton for EAR data analysis

    Mathematical model of brain tumour with glia-neuron interactions and chemotherapy treatment

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    Acknowledgements This study was possible by partial financial support from the following Brazilian government agencies: Fundação Araucária, EPSRC-EP/I032606/1 and CNPq, CAPES and Science Without Borders Program Process nos. 17656125, 99999.010583/2013-00 and 245377/2012-3.Peer reviewedPreprin

    Elimination of the numerical Cerenkov instability for spectral EM-PIC codes

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    When using an electromagnetic particle-in-cell (EM-PIC) code to simulate a relativistically drifting plasma, a violent numerical instability known as the numerical Cerenkov instability (NCI) occurs. The NCI is due to the unphysical coupling of electromagnetic waves on a grid to wave-particle resonances, including aliased resonances, i.e., ω+2πμ/Δt=(k1+2πν1/Δx1)v0\omega + 2\pi\mu/\Delta t=(k_1+ 2\pi\nu_1/\Delta x_1)v_0, where μ\mu and ν1\nu_1 refer to the time and space aliases and the plasma is drifting relativistically at velocity v0v_0 in the 1^\hat{1}-direction. Recent studies have shown that an EM-PIC code which uses a spectral field solver and a low pass filter can eliminate the fastest growing modes of the NCI. Based on these studies a new spectral PIC code for studying laser wakefield acceleration (LWFA) in the Lorentz boosted frame was developed. However, we show that for parameters of relevance for LWFA simulations in the boosted frame, a relativistically drifting plasma is susceptible to a host of additional unstable modes with lower growth rates, and that these modes appear when the fastest growing unstable modes are filtered out. We show that these modes are most easily identified as the coupling between modes which are purely transverse (EM) and purely longitudinal (Langmuir) in the rest frame of the plasma for specific time and space aliases. We rewrite the dispersion relation of the drifting plasma for a general field solver and obtain analytic expressions for the location and growth rate for each unstable mode, i.e, for each time and space aliased resonances. We show for the spectral solver that when the fastest growing mode is eliminated a new mode at the fundamental resonance (μ=ν1=0\mu=\nu_1=0) can be seen. (Please check the whole abstract in the paper).Comment: 36 pages, 12 figure

    Metal reduction in wine using PVI-PVP copolymer and its effects on chemical and sensory characters

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    We studied the influence of an adsorbent PVI-PVP resin (a copolymer of vinylimidazole and vinylpyrrolidone), on the removal of heavy metals in wines, mainly copper (Cu), iron (Fe), lead (Pb), cadmium (Cd) and aluminium (Al). The study also investigated the influence of PVI-PVP on the physical-chemical and sensory characteristics of white and red wines, comparing its effect when applied in the must and in the wine. The removal of metals was more effective when PVI-PVP was applied to the wine than to the must. The removal of Fe and Pb was more effective in white wines than in red wines, while the removal of Cu and Al was higher in red wines. In general, the higher the PVI-PVP dose, the greater the quantity of metallic elements (copper, iron, lead and aluminium) that are removed. PVI-PVP had a minor effect on phenolic composition. The wines showed some decrease in total acidity and an increase in pH with PVI-PVP. The application of PVI-PVP at the dose rates employed here did not affect the wine’s sensory characteristics significantly

    Nutritional quality of Vidal grass (Bothriochloa saccharoides) under dry tropical conditions

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    P?ginas 51-55Recurso Electr?nicoEste articulo contiene informaci?n acerca del pasto Vidal (Botriochloa saccharoides), gram?nea poco estudiada y que posee grandes cualidades a nivel nutricional y productivo tanto en monocultivo como en asociaci?n con especies arb?reas. Durante el desarrollo de esta investigaci?n se evaluaron las caracter?sticas de calidad nutricional del pasto Vidal durante sus diferentes etapas fenol?gicas (germinaci?n, vegetativa, reproductiva y senescencia). Para ello se estableci? una parcela en la granja ?CURDN? (Centro Universitario Regional del Norte del Tolima) ubicada en el municipio de Armero Guayabal. El ensayo fue desarrollado con el objetivo de determinar las caracter?sticas nutricionales m?s relevantes durante el desarrollo del ciclo del pasto Vidal. Seg?n los resultados obtenidos el pasto Botriochloa saccharoides present? un ciclo fenol?gico de 137 d?as, tiempo en el cual se observaron las fases de germinaci?n, prefloraci?n, floraci?n y senescencia a los 37, 91, 114 y 128 d?as respectivamente. El tiempo ideal para el primer pastoreo es aproximadamente a los 91 d?as etapa en la cual el pasto est? en estado de prefloraci?n con una PC de 5,24%; DIVMS 54,21%; 45,8% de FDA y 8,3% de lignina.ABSTRACT. This article contains information about Vidal grass (Botriochloa saccharoides) , which has been little studied although it has good nutritional and productive qualities as much in single-crop farming as in association with arboreal species. Throughout this project, the Characteristics of nutritional quality of Vidal grass were evaluated during their different stages of development (germination, vegetative, reproductive and senescence,). Then, an experimental plot was sown in the ?CURDN? farm (Centro Universitario Regional del Norte del Tolima), located in the municipality of Armero - Guayabal. According to the results obtained, the Botriochloa saccharoides grass presented a cycle of 137 days. The germination, vegetative, reproductive and senescence phases could be observed at the 37th , 91st , 114th and 128th days, respectively. The ideal time for the first harvest is immediately after the first stage is over (91 days), stage in which the grass has a CP of 5,24%; DMIVD 54,21%; 72,1% of ADF and 8,3% lignin
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