Distribution of asteroid genera (Echinodermata) off South Shetland Islands and the Antarctic Peninsula

Se analizan la frecuencia y distribución de los géneros de Asteroidea en la zona de las islas Shetland del Sur a partir en los datos obtenidos en 24 arrastres con Agassiz efectuados durante la campaña Bentart 95. Las estrellas fueron recogidas en más del 90 % de las estaciones, sobre todo tipo de fondos, con riqueza que osciló entre 0-10 géneros. Los asteroideos encontrados pertenecieron a 27 géneros y 12 familias, siendo Astropectinidae, Goniasteridae y, sobre todo, Asteriidae, las familas con el número más elevado de representantes (3 y 7 géneros, respectivamente). Odontaster Verrill, 1880 y Labidiaster Lütken, 1872, seguidos por Psilaster Sladen, 1885 y Diplasterias Perrier, 1888 presentaron la más amplia distribución y la frecuencia más elevada. Odontaster fue más frecuente hasta 100 m de profundidad y Labidiaster entre 200-300 m. Los géneros más raros fueron Notioceramus Fisher, 1940 y Chitonaster Sladen, 1889, endémicos de aguas antárticas. Las estaciones que mostraron una riqueza más alta (10 géneros) fueron las localizadas cerca de la península antártica y el norte de la isla Livingston. La pobreza de asteroideos fue notable en el interior de la isla Decepción, donde se encontraron sólo tres géneros.Frequency and distribution of asteroid genera in the South Shetlands zone are analysed, based on data from 24 Agassiz trawls carried out during the Bentart 95 Survey. Asteroids were collected at more than 90 % of the stations, on all types of bottoms, with richness per station ranging from 0-10 genera. The specimens belonged to 27 genera and 12 families, with Astropectinidae, Goniasteridae and, above all, Asteriidae having the highest number of representatives (3 and 7 genera, respectively). Odontaster Verrill, 1880 and Labidiaster Lütken, 1872, followed by Psilaster Sladen, 1885 and Diplasterias Perrier, 1888, were found to have the widest distribution and highest occurrence. Odontaster was more frequent to a depth of 100 m, and Labidiaster between 200 and 300 m. The rarest genera were Notioceramus Fisher, 1940 and Chitonaster Sladen, 1889, endemic to Antarctic waters.Stations showing the highest richness (10 genera) were those located near the Antarctic Peninsula and north of Livingston Island. Asteroid poverty was noticeable inside Deception Island, where a mere 3 genera were recorded. As shown by similarity and grouping analysis based on presence-absence data, stations are mainly grouped in relation to genera richness when double absence is considered. These results show the distintiveness of the stations around Deception Island, probably due to its special geological characteristics.Instituto Español de Oceanografí

X-boson Cumulant Approach To The Topological Kondo Insulators

In this work we present a generalization of our previous work of the X-boson approach to the periodic Anderson model (PAM), adequate to study a novel class of intermetallic 4f and 5f orbitals materials: the topological Kondo insulators, whose paradigmatic material is the compound SmB6. For simplicity, we consider a version of the PAM on a 2D square lattice, adequate to describe Ce-based compounds in two dimensions. The starting point of the model is the 4f - Ce ions orbitals, with J 5/2 multiplet, in the presence of spin-orbit coupling. Our technique works well for all of the parameters of the model and avoids the unwanted phase transitions of the slave boson mean field theory. We present a critical comparison of our results with those of the usual slave boson method, that has been intensively used to describe this class of materials. We also obtain a new valence first order transition which we attribute to the dependence of the hybridization.568DIB; Dirección de Investigación, Universidad Nacional de ColombiaColeman, P., (1984) Phys. Rev., 29 (6), p. 3035Dzero, M., Sun, K., Galitski, V., Coleman, P., (2010) Phys. Rev. Lett., 104 (10), p. 106408Dzero, M., Sun, K., Coleman, P., Galitski, V., (2012) Phys. Rev., 85 (4), p. 045130Alexandrov, V., Dzero, M., Coleman, P., (2013) Phys. Rev. Lett., 111 (22), p. 226403Tran, M.T., Takimoto, T., Kim, K.S., (2012) Phys. Rev., 85 (12), p. 125128Legner, M., Rueg, A., Sigrist, M., Phys. Rev., 89, p. 085110Werner, J., Assaad, F.F., (2013) Phys. Rev., 88 (3), p. 035113Franco, R., Figueira, M.S., Foglio, M.E., (2003) Phys. Rev., 66 (4), p. 045112Steglich, F., Geibel, C., Gloss, K., Olesch, G., Schank, C., Wassilew, C., Loidl, A., Stewart, G.F., (1994) J. Low Temperature Phys., 95 (1-2), p. 3Derr, J., Knebel, G., Lapertot, G., Salce, B., Measson, M.-A., Flouquet, J., (2006) J. Phys.: Condens. Matter, 18 (6), p. 2089Natoli, V.D., Cohen, H.M., Fornberg, B., (1996) J. Computacional Phys., 126 (1), p. 9

Distribución y ecología de Ophionotus victoriae Bell, 1902 (Ophiuroidea, Echinodermata) en el área de las islas Shetland del Sur (Antártida)

We present a distribution analysis for Ophionotus victoriae Bell, 1902, based on abundance data obtained during the Bentart 95 Expedition, on a macrozoobenthos sampling transect from north of Livingston Island to the Antarctic Peninsula, with 24 Agassiz trawls carried out at depths of 40- 850 m. This ophiuroid seems characteristic of the macrobenthic assemblages south of Livingston Island and Deception, where the species represents 60-90% of numerical abundance and 40-80% of biomass for the total epifauna. Pearson and Spearman coefficients correlation showed interesting results which could explain the success of O. victoriae in this area. The highest O. victoriae abundances were related to acidic and carbonated sediments, as well as to mysid density; moreover, the presence of the largest specimens was apparently related to euphasids, and we also found a negative relationship with a filter- feeder biomass.Durante la Campaña Bentart 95 se muestreó el macrozoobentos en 24 estaciones con draga de arrastre Agassiz y a profundidades comprendidas entre 40 y 850 m, sobre un recorrido que cubrió desde el norte de la isla Livingston hasta la península Antártica. A partir de los datos de abundancia obtenidos se analiza la distribución de Ophionotus victoriae Bell, 1902. Esta ofiura parece caracterizar las comunidades macrobentónicas en las zonas al sur de Livingston y en la isla Decepción, donde constituye entre el 60 y el 90%, y del 40 al 80 % de la abundancia numérica y la biomasa, respectivamente, del total de la epifauna. La aplicación de las correlaciones de Pearson y Spearman arroja resultados interesantes que podrían explicar el éxito de O. victoriae en esta región. Las mayores abundancias de O. victoriae se relacionarían con los sedimentos acidificados y con la mayor concentración de carbonatos, así como con la densidad de misidáceos; mientras, se observa una relación negativa con la biomasa de filtradores, y la presencia de ejemplares de mayor tamaño parece relacionada directamente con la presencia de eufasiáceos.Instituto Español de Oceanografí

Helium mixtures in nanotube bundles

An analogue to Raoult's law is determined for the case of a 3He-4He mixture adsorbed in the interstitial channels of a bundle of carbon nanotubes. Unlike the case of He mixtures in other environments, the ratio of the partial pressures of the coexisting vapor is found to be a simple function of the ratio of concentrations within the nanotube bundle.Comment: 3 pages, no figures, submitted to Phys. Rev. Let

General dissipation coefficient in low-temperature warm inflation

In generic particle physics models, the inflaton field is coupled to other bosonic and fermionic fields that acquire large masses during inflation and may decay into light degrees of freedom. This leads to dissipative effects that modify the inflationary dynamics and may generate a nearly-thermal radiation bath, such that inflation occurs in a warm rather than supercooled environment. In this work, we perform a numerical computation and obtain expressions for the associated dissipation coefficient in supersymmetric models, focusing on the regime where the radiation temperature is below the heavy mass threshold. The dissipation coefficient receives contributions from the decay of both on-shell and off-shell degrees of freedom, which are dominant for small and large couplings, respectively, taking into account the light field multiplicities. In particular, we find that the contribution from on-shell decays, although Boltzmann-suppressed, can be much larger than that of virtual modes, which is bounded by the validity of a perturbative analysis. This result opens up new possibilities for realizations of warm inflation in supersymmetric field theories.Comment: 25 pages, 13 figures; revised version with new results added; published in JCA

Chiral drug analysis in forensic chemistry: An overview

Many substances of forensic interest are chiral and available either as racemates or pure enantiomers. Application of chiral analysis in biological samples can be useful for the determination of legal or illicit drugs consumption or interpretation of unexpected toxicological effects. Chiral substances can also be found in environmental samples and revealed to be useful for determination of community drug usage (sewage epidemiology), identification of illicit drug manufacturing locations, illegal discharge of sewage and in environmental risk assessment. Thus, the purpose of this paper is to provide an overview of the application of chiral analysis in biological and environmental samples and their relevance in the forensic field. Most frequently analytical methods used to quantify the enantiomers are liquid and gas chromatography using both indirect, with enantiomerically pure derivatizing reagents, and direct methods recurring to chiral stationary phases. © 2018 by the authors.Acknowledgments: This work was partially supported through national funds provided by FCT/MCTES- Foundation for Science and Technology from the Minister of Science, Technology and Higher Education (PIDDAC) and European Regional Development Fund (ERDF) through the COMPETE-Programa Operacional Factores de Competitividade (POFC) programme, under the Strategic Funding UID/Multi/04423/2013, the project PTDC/MAR-BIO/4694/2014 (reference POCI-01-0145-FEDER-016790; Project 3599-Promover a Producao Cientifica e Desenvolvimento Tecnologico e a Constituicao de Redes Tematicas (3599-PPCDT)) in the framework of the programme PT2020 as well as by the project INNOVMAR-Innovation and Sustainability in the Management and Exploitation of Marine Resources (reference NORTE-01-0145-FEDER-000035, within Research Line NOVELMAR), supported by North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and Chiral_Drugs_CESPU_2017

Opening the GATE : systems thinking from the global assistive technology alliance

Purpose: This paper describes international actions to collaborate in the assistive technology (AT) arena and provides an update of programmes supporting AT globally. Methods: The World Health Organisation (WHO) identifies the severe global uneven distribution of resources, expertise and extensive unmet need for AT, as well the optimistic substantial capability for innovations and developments in appropriate and sustainable AT design, development and delivery. Systems thinking and market shaping are identified as means to address these challenges and leverage the ingenuity and expertise of AT stakeholders. Results: This paper is a ‘call to action’, showcasing emerging AT networks as exemplars of a distributed, but integrated mechanism for addressing AT needs globally, and describing the Global Alliance of Assistive Technology Organisations (GAATO) as a vehicle to facilitate this global networking. Conclusion: Partners in this Global Alliance aim to advance the field of assistive technology by promoting shared research, policy advocacy, educating people and organisations within and outside the field, teaching, training and knowledge transfer by pulling together broad-based membership organisations