786 research outputs found

    Effective-Hamiltonian parameters for \emph{ab initio} energy-level calculations of SrCl2_{2}:Yb2+^{2+} and CsCaBr3_{3}:Yb2+^{2+}

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    Calculated energy levels from recent \emph{ab initio} studies of the electronic structure of SrCl2_{2}:Yb2+^{2+} and CsCaBr3_{3}:Yb2+^{2+} are fitted with a semi-empirical "crystal-field" Hamiltonian, which acts within the model space 4f14+4f135d+4f136s4f^{14} + 4f^{13}5d + 4f^{13}6s. Parameters are obtained for the minima of the potential-energy curves for each energy level and also for a range of anion-cation separations. The parameters are compared with published results parameters fitted to experimental data and to atomic calculations. The states with significant 4f136s4f^{13}6s character give a good approximation of the impurity-trapped exciton states that appear in the \emph{ab initio} calculations.Comment: Minor revisio

    The Nekton Maldives taxonomic workshop: exploring the biodiversity of shallow, mesophotic and deep-sea communities in Maldives

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    The Nekton Maldives Taxonomic Workshop took place at the Maniyafushi Research Station in the Maldives between 12 and 23 February 2023. This workshop had two primary objectives. Firstly, it aimed to identify species from biological samples and underwater imagery collected during the Nekton Maldives Mission in 2022. Secondly, it sought to facilitate training and knowledge exchange sessions between early career researchers from the Maldives and international taxonomists. These sessions were designed to share knowledge and introduce fundamental taxonomy concepts and enhance practical identification skills for common reef benthic groups and major zooplankton taxonomic groups. A total of 24 people from 10 different countries were directly or indirectly involved with the workshop comprising nine taxonomic experts, eleven trainees and four organisers. Collectively, we identified 278 biological specimens including potentially undescribed species of hydroids, black corals, sponges and octocorals, 318 morphotypes for underwater footage and zooplankton composition congruent with previous reports from the Indian Ocean Region. Next steps will involve depositing the specimens into a more a permanent facility to facilitate the process of specimen description and knowledge transfer

    Firewood and timber exploitation during the 3rd and 2nd millennia BC in the Western façade of the Iberian Northwest: wooden resources, territories and chaîne opératoire

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    As sociedades humanas estabelecem toda uma série de estratégias produtivas destinadas a obter os meios materiais necessários para a sua existência, entre elas, o aprovisionamento de lenha e de madeira. Estas estratégias, além de estarem condicionadas pela oferta ambiental, são igualmente resultantes das características culturais e das capacidades técnicas. Os dados arqueobotânicos que se apresentam procedem de vários lugares de habitação do Calcolítico e da Idade do Bronze da fachada ocidental do Noroeste peninsular com cronologias que abarcam o III e parte do II milénios AC (Martin em preparação; Martín et al. no prelo; Figueiral e Bettencourt 2007). Os resultados obtidos permitiram identificar uma exploração diversificada dos recursos lenhosos que combinava a recolha de lenha e de madeira das áreas da floresta climácica com a proveniente das áreas de mato. As formaçãos arbóreas situadas nas margems dos cursos de água também constituíram fonte de aprovisionamento de combustíveis e, provavelmente, de madeira. A caracterização dos recursos usados em cada um dos casos de estudo permitiu-nos, igualmente, colocar hipóteses sobre o território de vivência, de circulação e de exploração de cada comunidade. A análise dendrológica das amostras registando o grau de curvatura dos anéis de crescimento anual, o diâmetro mínimo dos ramos ou troncos consumidos, a presença de tiloses e de depósitos de resina, a presença de madeira de reação, a conservação do floema e ou da casca, a presença ou a ausência de cicatrizes ou de anéis sinuosos, as mudanças no ritmo de crescimento, entre outras características, em inter-relação com determinados contextos arqueológicos (dimensões dos buracos de poste, por exemplo), proporcionaram, também, hipóteses relacionadas com a cadeia técnica-operativa dos recursos florestais. Ou seja, sobre a sucessão de operações realizadas pelas comunidades humanas desde a extração da matéria até à sua utilização final.This research was developed under the projects: A xestión do bosque e do monte dende a Idade do Ferro a época romana no noroeste da península Ibérica: consumo de combustibles e produción de manufacturas en madeira / Forest and scrubland management from Iron Age to roman period in the Northwest of the Iberian peninsula: firewood consumption and wooden manufacture production, IDEPatri-Deseño e desenvolvemento dun modelo de datos para unha IDE arqueolóxica da Idade do Ferro en Galicia /IDEPatri- Design and development of a data model for an archaeological SPI during the Galician Iron Age: (IDEPatri) 09SEC002CT. Xunta de Galicia, Paisagens da Idade do Bronze no ocidente peninsular / Bronze Age Landscapes in the West of Iberian Peninsula - SFRH/BSAB/986/10 e Geoindicators of natural and anthropogenic palaeoenvironmental evolution in the Portuguese NW, during de Holocene – 2010_CGUP/CCT/UM

    Chemical profile from the head of Vespa velutina and V. crabro

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    Vespa velutina and V. crabro are eusocial insects in which chemical communication is decisive for social interactions. V. velutina was accidentally introduced in 2004 in France and subsequently in northern Spain in 2010. It is an invasive species that severely affects the beekeeping sector. The hornet autochthonous V. crabro with a similar ecological niche is captured in bait traps used to control V. velutina populations. Insect cuticle and head structures had an important role in chemical communication so that this research approaches for the first time chemical compounds extracted from the heads of V. velutina and V. crabro. Chemical compounds were profiled using GC/MS. The main compounds identified were carbohydrates, fatty acids, and hydrocarbons. The chemical profile of both species was compared and also an intrinsic differentiation was made between queens and workers in V. velutina. Chemometric techniques (PCA and LSD) were used to achieve this goal.This work was supported by the co-financing of Xunta de Galicia Postdoctoral Financial Aids (Department of Culture, Education and University Organization) together with the University of Vigo [reference number ED481B-2018/059]. The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UIDB/00690/2020). Falcão, S. I. thanks National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

    Description of the volatile fraction of Erica honey from the northwest of the Iberian Peninsula

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    Heather honey is highly appreciated by consumers for its sensorial profile, which varies depending on the flora used by the honeybees. Volatile compounds contribute to these qualities. Characterisation of the volatile profile related to the botanical origin is of great interest for the standardization of unifloral honey. For this reason, 33 heather honey samples from northwest of the Iberian Peninsula were analysed by headspace solid-phase microextraction (HS-SPME) to identify the key volatile compounds in this type of honey. The aim of this research was to provide a descriptive analysis of these compounds, and to find whether there is any relationship with the main Erica species. A total of 58 volatile organic compounds were found, with hotrienol, phenylacetaldehyde, and cis-linalool being the most abundant. A principal component analysis and Spearman's rank correlation showed the homogeneity of the volatile profile in the samples, and their close relationship with the main pollen types.The authors would like to thank the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020). S. I. Falcão thanks for the national funding provided by FCT-Foundation for Science and Technology, through the institutional scientific employment program contract.info:eu-repo/semantics/publishedVersio

    Cytogenetic evidences on the evolutionary relationships between the tetraploids of the section Rhizomatosae and related diploid species (Arachis, Leguminosae).

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    Made available in DSpace on 2018-08-10T00:41:31Z (GMT). No. of bitstreams: 1 Ortiz2017ArticleCytogeneticEvidencesOnTheEvolu.pdf: 1816719 bytes, checksum: fbb7f89bca811a5e4ba5a2d9061e1341 (MD5) Previous issue date: 2017-07-27bitstream/item/181202/1/Ortiz2017-Article-CytogeneticEvidencesOnTheEvolu.pd

    Improvisation in times of pandemic, a reason for reflection

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    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been one of the most significant health crises worldwide in the last decades. This new pandemic has brought to light the strengths and weaknesses of current health care systems worldwide, even in countries that pride themselves on being at the forefront in terms of clinical, scientific, and technological capacity and development. Crises such as these are also opportunities to reflect and learn. Coronavirus disease 2019 (COVID-19) has provided us with several valuable lessons that involve the whole spectrum of medical practice: human, scientific, technical, and social
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