A new construction of Lagrangians in the complex Euclidean plane in terms of planar curves

We introduce a new method to construct a large family of Lagrangian surfaces in complex Euclidean plane by means of two planar curves making use of their usual product as complex functions and integrating the Hermitian product of their position and tangent vectors. Among this family, we characterize minimal, constant mean curvature, Hamiltonian stationary, solitons for mean curvature flow and Willmore surfaces in terms of simple properties of the curvatures of the generating curves. As an application, we provide explicitly conformal parametrizations of known and new examples of these classes of Lagrangians in complex Euclidean plane.Comment: 15 pages, 5 figure

Effect of thermal shock and ruminal incubation on seed germination in Helianthemum apenninum L. Mill (Cistaceae)

Effect of thermal shock and ruminal incubation on seed germination in Helianthemum apenninum (L.) Mill. (Cistaceae). Here, we analyse the effect of different treatments on seed germination in Helianthemum apenninum (L.) Mill. (Cistaceae), considering scarification with sandpaper, thermal shock simulating the heat from fire, and incubation in the rumen of sheep and goat simulating passage through the gut of ruminants. Mechanical scarification boosted the germination (95% vs. 6% of control treatment), indicating that the seeds have a potentially high germination rate if the coat is eroded. Thermal shock did not improve germination. Incubation in rumen increased seed germination, up to a 32% after 48h in ruminal liquid versus 12% for control seeds in the case of sheep. The results suggest that germination in H. apenninum, while not enhanced by heat from fires, may be enhanced by herbivore ingestion

Constraints to the magnetospheric properties of T Tauri stars. I. The C II], Fe II] and Si II] ultraviolet features

The C II] feature at ~2325 Angstrom is very prominent in the spectra of T Tauri stars (TTSs). This feature is a quintuplet of semiforbidden transitions excited at electron temperatures around 10,000 K that, together with the nearby Si II] and Fe II] features, provides a reliable optically thin tracer for accurate measurement of the plasma properties in the magnetospheres of TTSs. The spectra of 20 (out of 27) TTSs observed with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST) have good enough signal to noise ratio (S/N) at the C II] wavelength. For these stars we have determined electron densities (ne) and temperatures (Te) in the line emission region as well as the profile broadening (sigma). For most of the stars in the sample (17) we obtain 10^{4.1} < Te < 10^{4.5} K and 10^{8} < ne < 10^{12} cm^{-3}. These stars have suprathermal line broadening (35 < sigma < 165 km s^{-1}), except TW Hya and CY Tau with thermal line broadening. Both C II] line luminosity and broadening are found to correlate with the accretion rate. Line emission seems to be produced in the magnetospheric accretion flow, close to the disk. There are three exceptions: DG Tau, RY Tau and FU Ori. The line centroids are blueshifted indicating that the line emission in these three stars is dominated by the outflow.Comment: 13 pages, 15 figures, published in MNRAS minor change

A data base of synthetic photometry in the GALEX ultraviolet bands for the stellar sources observed with the International Ultraviolet Explorer

The Galaxy Evolution Explorer (GALEX) has produced the largest photometric catalogue of ultraviolet (UV) sources. As such, it has defined the new standard bands for UV photometry: the near UV band (NUV) and the far UV band (FUV). However, due to brightness limits, the GALEX mission has avoided the Galactic plane which is crucial for astrophysical research and future space missions. The International Ultraviolet Explorer (IUE) satellite obtained 63,755 spectra in the low dispersion mode during its 18 years lifetime. We have derived the photometry in the GALEX bands for the stellar sources in the IUE Archive to extend the GALEX data base with observations including the Galactic plane.Good quality spectra have been selected for all IUE classes of stellar sources. The GALEX FUV and NUV magnitudes have been computed using the GALEX transmission curves, as well as the conversion equations between flux and magnitudes provided by the mission (galexgi.gsfc.nasa.gov). Consistency between GALEX and IUE synthetic photometries has been tested using White Dwarfs (WD) contained in both samples. The non-linear response performance of GALEX inferred from this data agrees with the results from GALEX calibration. The photometric data base is made available to the community through the services of the Centre de Donn\'ees Stellaires at Strasbourg (CDS). The catalogue contains FUV magnitudes for 1,631 sources, ranging from FUV=1.81 to FUV=18.65 mag. In the NUV band, the catalogue includes observations for 1,005 stars ranging from NUV = 3.08 to NUV= 17.74 mag . UV photometry for 1,493 not included in the GALEX AIS GR5 catalogue is provided; most of them are hot (O-A spectral type) stars. The sources in the catalogue are distributed over the full sky, including the Galactic plane.Comment: Submitted to Astronomy & Astrophysic

Constraints to the magnetospheric properties of T Tauri stars - II. The Mg II ultraviolet feature

The atmospheric structure of T Tauri Stars (TTSs) and its connection with the large scale outflow is poorly known. Neither the effect of the magnetically mediated inter- action between the star and the disc in the stellar atmosphere is well understood. The Mg II multiplet is a fundamental tracer of TTSs atmospheres and outflows, and is the strongest feature in the near-ultraviolet spectrum of TTSs. The International Ultraviolet Explorer and Hubble Space Telescope data archives provide a unique set to study the main physical compounds contributing to the line profile and to derive the properties of the line formation region. The Mg II profiles of 44 TTSs with resolution 13,000 to 30,000 are available in these archives. In this work, we use this data set to measure the main observables: flux, broadening, asymmetry, terminal velocity of the outflow, and the velocity of the Discrete Absorption Components. For some few sources repeated observations are available and variability has been studied. There is a warm wind that at sub-AU scales absorbs the blue wing of the Mg II profiles. The main result found in this work is the correlation between the line broadening, Mg II flux, terminal velocity of the flow and accretion rate. Both outflow and magnetospheric plasma contribute to the Mg II flux. The flux-flux correlation between Mg II and C IV or He II is confirmed; however, no correlation is found between the Mg II flux and the ultraviolet continuum or the H2 emission.Comment: 21 pages, 20 figure

Marginalized narratives

This issue of CITAR (Journal of Arts Science and Technology) is especially devoted to what we designated as Marginalized Narratives. It is a special issue that collects studies published upon the 5th Colloquium on Narrative, Medium and Cognition, held at the University of Algarve in November 2018, and which was focused on that topic. In line with what the colloquium proposed, the works now published share a broad understanding of the concept of narrative.info:eu-repo/semantics/publishedVersio