Symplectic duality of Symmetric Spaces

We show that between symmetric spaces of different types there exists a bi-symplectic map. We compute the duality map explicitely by using the theory of Jordan Algebra

Digital transformation of higher education in Australia: Understanding affordance dynamics in E-Textbook engagement and use

This paper addresses digital transformation in higher education by exploring the engagement and use of e-textbooks through an affordance theory lens. Drawing on the insights from in-depth interviews (n = 18), focus group discussions (n = 15), a pilot survey (n = 83) and the main survey (n = 344) in Australia, we developed and validated an affordance actualisation model for the engagement and use of e-textbooks. The partial least squares (PLS) technique was used to validate the dimensions of affordance actualisation and its relationship with e-textbooks engagement and affordance effect. The findings indicate the efficacy of the two affordance constructs, as well as the significant mediating effect of engagement. An important lesson for the e-textbook industry is that firms need to consider affordance actualisation dimensions (i.e., portability, accessibility, searchability, highlighting, copying, browsing, hedonic and utilitarian value) when enhancing digital engagement and use of e-textbooks

Slow Diffeomorphisms of a Manifold with Two Dimensions Torus Action

The uniform norm of the differential of the n-th iteration of a diffeomorphism is called the growth sequence of the diffeomorphism. In this paper we show that there is no lower universal growth bound for volume preserving diffeomorphisms on manifolds with an effective two dimensions torus action by constructing a set of volume-preserving diffeomorphisms with arbitrarily slow growth.Comment: 12 p

Timing chirurgico nell’adenoma epatico sanguinante: case report

La diagnosi di adenoma epatico, la cui eziopatogenesi è spesso un rapporto con l’assunzione prolungata di estroprogestinici (il 90% degli adenomi si osserva in donne che hanno preso la ‘pillola’ per più di 5 anni), impone sempre una indicazione chirurgica resettiva. La ragione è data dalle caratteristiche peculiari della neoplasia, che sono la degenerazione maligna (4%) e l’elevato rischio di sanguinamento (30- 50%), intratumorale e/o intraaddominale, che aumenta in gravidanza e in puerperio. La regressione dopo sospensione della terapia ormonale, infatti, è poco frequente e non elimina il rischio di degenerazione e/o emorragia. La resezione epatica dovrebbe essere condotta in combinazione con appropriate procedure di embolizzazione endovascolare selettiva, considerato che la chirurgia in emergenza potrebbe imporre un sacrificio epatico maggiore, esponendo il paziente a morbilità e mortalità più elevate. I tempi di attesa dall’embolizzazione all’intervento elettivo non sono standardizzati e sono pertanto indicati dall’esperienza personale e soprattutto da un attento e seriato follow-up del paziente. Gli Autori riportano la propria esperienza nella strategia terapeutica e nel timing chirurgico di un caso di adenoma epatico sanguinante

Las estructuras centrales de la Galaxia Seyfert NGC 7582

La ponencia fue originalmente presentada en la Reunión Anual de la Asociación Argentina de Astonomía : San Juan : 2016. Y publicada en el Boletín de la Asociación Argentina de Astronomía, vol 59, en el año 2017.Fil: Celiz, Denise. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Gaspar, Gaia. Universidad Nacional de Córdoba. Observatorio Astronómico Córdoba; Argentina.Fil: Díaz, Rubén J. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Díaz, Rubén J. Gemini Observatory; ChileFil: D'Ambra, Ary. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Presentamos la primera fase del estudio de la galaxia Seyfert NGC 7582 mediante imágenes NIR de alta resolución espacial tomadas con el instrumento Flamingos-2 de Gemini Sur. NGC 7582 posee un núcleo de tipo Seyfert 2 que en el año 1998 experimentó un cambio inusual en su espectro de emisión óptico, permaneciendo como un núcleo Seyfert 1 por algunos meses. Además, variaciones en su espectro en el rango de los rayos X han sido interpretadas como evidencia de la naturaleza grumosa del material absorbedor circumnuclear, entendido como un toroide en el marco del Modelo Unificado. Estas peculiaridades y el hecho de que la galaxia se encuentre muy inclinada con respecto al plano del cielo, la convierten en candidata apta para la exploración profunda en el rango espectral infrarrojo. En éste trabajo presentamos imágenes de alta resolución de la galaxia, a partir de las cuales caracterizamos las regiones más centrales, en especial el anillo circumnuclear y una estructura tipo ”boxy”poco estudiada hasta la fecha. Realizamos fotometrı́a de apertura del núcleo para diferentes radios. Encontramos que las magnitudes medidas son consistentes con las reportadas en la literatura para épocas anteriores, indicando que el núcleo no ha sufrido variaciones dramáticas durante la época observada.We present the first stage of the study of the Seyfert Galaxy NGC 7582 through high spatial resolution NIR images obtained with the instrument Flamingos-2 of Gemini South. NGC 7582 harbours a Seyfert 2 nucleus that in 1998 experienced an unusual change in its optical emission line spectrum, remaining as a Seyfert 1 nucleus for some months. Moreover, variations in its X-ray spectrum have been interpreted as evidence of the clumpy nature of the circumnuclear absorbing material, conseived as a torus in the Unified Model. These peculiarities plus the high inclination of the galaxy make it a suitable candidate for deep infrared observations. In this work we present high resolution images of the galaxy, from wich we caracterized the most central regions, specially the circumnuclear ring and a ”box-type” structure, little studied to date. We performed aperture photometry of the nucleus for different radii. We find that the measured magnitudes are consistent with those reported in the literature for previous epochs, indicating that the nucleus has not suffered dramatic variations during this observation epoch.Fil: Celiz, Denise. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Fil: Gaspar, Gaia. Universidad Nacional de Córdoba. Observatorio Astronómico Córdoba; Argentina.Fil: Díaz, Rubén J. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Astronómicas, de la Tierra y del Espacio; ArgentinaFil: Díaz, Rubén J. Gemini Observatory; ChileFil: D'Ambra, Ary. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Astronomía (incluye Astrofísica y Ciencias del Espacio

Tackling the jelly web: Trophic ecology of gelatinous zooplankton in oceanic food webs of the eastern tropical Atlantic assessed by stable isotope analysis

Gelatinous zooplankton can be present in high biomass and taxonomic diversity in planktonic oceanic food webs, yet the trophic structuring and importance of this “jelly web” remain incompletely understood. To address this knowledge gap, we provide a holistic trophic characterization of a jelly web in the eastern tropical Atlantic, based on δ13C and δ15N stable isotope analysis of a unique gelatinous zooplankton sample set. The jelly web covered most of the isotopic niche space of the entire planktonic oceanic food web, spanning > 3 trophic levels, ranging from herbivores (e.g., pyrosomes) to higher predators (e.g., ctenophores), highlighting the diverse functional roles and broad possible food web relevance of gelatinous zooplankton. Among gelatinous zooplankton taxa, comparisons of isotopic niches pointed to the presence of differentiation and resource partitioning, but also highlighted the potential for competition, e.g., between hydromedusae and siphonophores. Significant differences in spatial (seamount vs. open ocean) and depth‐resolved patterns (0–400 m vs. 400–1000 m) pointed to additional complexity, and raise questions about the extent of connectivity between locations and differential patterns in vertical coupling between gelatinous zooplankton groups. Added complexity also resulted from inconsistent patterns in trophic ontogenetic shifts among groups. We conclude that the broad trophic niche covered by the jelly web, patterns in niche differentiation within this web, and substantial complexity at the spatial, depth, and taxon level call for a more careful consideration of gelatinous zooplankton in oceanic food web models. In light of climate change and fishing pressure, the data presented here also provide a valuable baseline against which to measure future trophic observations of gelatinous zooplankton communities in the eastern tropical Atlantic

Systematic changes of the Nb-Sn reaction with time, temperature and alloying in Restacked-Rod-Process (RRP) Nb3Sn strands

Reaction heat treatments spanning 605 to 750 C and 24 to {approx}400 hours were applied to several sets of RRP strands. Magnetization and transport measurements were used to track the changes of superconducting properties and the amounts of Nb{sub 3}Sn formed. The experiments showed that temperature increases of 15 C produced equivalent properties in half the time within the temperature range 620-680 C. This result was the same whether Ta or Ti was used to alloy the Nb{sub 3}Sn. The bulk pinning force Fp for Ta-alloyed wires displayed a significant drop for temperatures outside the range above, due to tin gradients at low temperatures and grain growth at high temperatures. The F{sub p} drop at high reaction temperatures prevents wire technology from taking advantage of significantly higher Kramer-plot intercept H{sub K} for high-temperature reactions. On the other hand, Ti alloying provides a quick and potent means to increase H{sub K} at reaction temperatures for which F{sub p} remains high

Prospective randomized study comparing the Teleflex Medical SaphLITE Retractor to the Ethicon CardioVations Clearglide Endoscopic System

BACKGROUND: Several minimally invasive saphenous vein harvesting techniques have been developed to reduce morbidities associated with coronary artery bypass grafting. This prospective, randomized study was designed to compare two commonly used minimally invasive saphenous vein harvesting techniques, the SaphLITE Retractor System (Teleflex Medical) and the Clearglide Endoscopic Vessel Harvesting System (Ethicon CardioVations, Inc.). METHODS: Between January 2003 and March 2004, a total of 200 patients scheduled for primary, nonemergent coronary artery bypass grafting, with or without concomitant procedures were randomized into two groups: SaphLITE (n = 100) and Clearglide (n = 100). Pre-, intra- and postoperative data was collected and subjected to statistical analysis. Randomization provided homogenous groups with respect to preoperative risk factors. RESULTS: Harvest location for the SaphLITE group was thigh (n = 40), lower leg (n = 5) and both lower leg and thigh (n = 55). The location of harvest for the Clearglide group was thigh (n = 3), lower leg (n = 16) and both lower leg and thigh (n = 81). The mean incision length was 3.6 cm (range, 2–6) in the SaphLITE group versus 2.1 cm (range, 1–4) in the Clearglide group (p < 0.05). The total incision length was 12.9 cm versus 8.9 (p < 0.05) in the SaphLITE and Clearglide groups. Conversion to the open technique occurred in 5 SaphLITE patients and 7 Clearglide patients. Intraoperative leg exploration for bleeding occurred in two of the Clearglide patients and none of the SaphLITE patients. Post-operative complications specifically related to minimally invasive harvesting technique, including a two-week post-discharge visit, were not statistically different between the groups. CONCLUSION: The saphenous vein can be safely harvested utilizing the SaphLITE and Clearglide systems. While the Clearglide system allows for fewer incisions (number and length) and less harvest time, these benefits may be outweighed by the increased cost of the Clearglide system compared to the SaphLITE retractor

Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry

INTRODUCTION: Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions. METHOD: With the present retrospective pilot study we describe a method to transfer MV geometric data to 3D Slicer 2 software, an open-source medical visualization and analysis software package. A newly developed software program (ROIExtract) allowed selection of a region-of-interest (ROI) from the TEE data and data transformation for use in 3D Slicer. FEM models for quantitative volumetric studies were generated. RESULTS: ROI selection permitted the visualization and calculations required to create a sequence of volume rendered models of the MV allowing time-based visualization of regional deformation. Quantitation of tissue volume, especially important in myxomatous degeneration can be carried out. Rendered volumes are shown in 3D as well as in time-resolved 4D animations. CONCLUSION: The visualization of the segmented MV may significantly enhance clinical interpretation. This method provides an infrastructure for the study of image guided assessment of clinical findings and surgical planning. For complete pre- and intraoperative 3D MV FEM analysis, three input elements are necessary: 1. time-gated, reality-based structural information, 2. continuous MV pressure and 3. instantaneous tissue elastance. The present process makes the first of these elements available. Volume defect analysis is essential to fully understand functional and geometrical dysfunction of but not limited to the valve. 3D Slicer was used for semi-automatic valve border detection and volume-rendering of clinical 3D echocardiographic data. FEM based models were also calculated. METHOD: A Philips/HP Sonos 5500 ultrasound device stores volume data as time-resolved 4D volume data sets. Data sets for three subjects were used. Since 3D Slicer does not process time-resolved data sets, we employed a standard movie maker to animate the individual time-based models and visualizations. Calculation time and model size were minimized. Pressures were also easily available. We speculate that calculation of instantaneous elastance may be possible using instantaneous pressure values and tissue deformation data derived from the animated FEM