Singularities of Euler flow? Not out of the blue!

Does three-dimensional incompressible Euler flow with smooth initial conditions develop a singularity with infinite vorticity after a finite time? This blowup problem is still open. After briefly reviewing what is known and pointing out some of the difficulties, we propose to tackle this issue for the class of flows having analytic initial data for which hypothetical real singularities are preceded by singularities at complex locations. We present some results concerning the nature of complex space singularities in two dimensions and propose a new strategy for the numerical investigation of blowup.(A version of the paper with higher-quality figures is available at http://www.obs-nice.fr/etc7/complex.pdf)Comment: RevTeX4, 10 pages, 9 figures. J.Stat.Phys. in press (updated version

Exploring the formation of spheroidal galaxies out to z ∼ 1.5 in GOODS

The formation of massive spheroidal galaxies is studied on a visually classified sample extracted from the Advanced Camera for Surveys/Hubble Space Telescope (ACS/HST) images of the Great Observatories Origins Deep Survey north and south fields, covering a total area of 360 arcmin . The sample size (910 galaxies brighter than i = 24) allows us to explore in detail the evolution over a wide range of redshifts (0.4 10 M galaxies by a factor of 2 between z = 1 and 0, in contrast with a factor of ∼50 for lower mass galaxies (10 <M / M <10 ). One-quarter of the whole sample of early types are photometrically classified as blue galaxies. On a volume-limited sample out to z <0.7, the average stellar mass of the blue ellipticals is 5 × 10 M compared to 4 × 10 M for red ellipticals. On a volume-limited subsample out to z = 1.4 probing the brightest galaxies (M <-21), we find the median redshift of blue and red early types: 1.10 and 0.85, respectively. Blue early types only amount to 4 per cent of this sample (compared to 26 per cent in the full sample). The intrinsic colour distribution correlates overall bluer colours with blue cores (positive radial gradients of colour), suggesting an inside-out process of formation. The redshift evolution of the observed colour gradients is incompatible with a significant variation in stellar age within each galaxy. The slope of the Kormendy relation in the subsample of massive galaxies does not change over 0.4 <z <1.4 and is compatible with z = 0 values. The 'zero-point' of the Kormendy relation (i.e. the surface brightness at a fixed half-light radius) is 1 mag fainter (in the B band) for the subsample of low-mass (M <3.5 × 10 M ) early types.Peer reviewe

How events can influence in the customer experience at Out of the Blue Hostel: an internship storytelling

The growth of tourism is not an exception to Azores Islands that saw a big increase of tourists after the low cost airlines started flying to the islands in 2015. The whole market is in a process of adaptation and hostels is a new concept to the island and very appreciated to the ones who visit it. Out of the Blue hostel's concept is to turn each stay into a unique experience. So me and the owners of the hostel were brainstorming ideas how to improve the concept and together we decided to create Out Of The Blue Family Dinners, where every evening we prepare homemade dinners and take guests out on night tours, creating moments of sharing cultures, ideas, dreams and time on the island between the guest and the staff of the hostel. In this storytelling I am presenting how I started doing events at the hostel and the process of adaptation to the tourism trends, guest and management needs in order to create a high quality experience. In the end I will present the reviews left by the guests of the hostel on various booking platforms. After 6 months the impact of the events is very visible through the guest reviews and feedbacks, team satisfaction and sales revenue.O turismo em crescimento e não é uma exceção nas Ilhas dos Açores que viu este fenomeno acontecer após as low coast começarem a voar para as ilhas em 2015. Todo o mercado está a adaptar-se e os hostels é um novo conceito na ilha e muito apreciado para o aqueles que as visitam. O conceito Out of the Blue é transformar cada estadia em uma experiência única. Então, juntos começamos a fazer um brainstorm como melhorar o conceito. Juntos, decidimos começar a fazer eventos todas as noites que inclui jantares e passeios nocturos, criando momentos de partilha de cultura, ideias, sonhos e tempo na ilha. Esta storytelling que vos apresento consiste em começar a fazer eventos no hostel e todo o processo de adaptação às tendências de turismo, hospedes e necessidades de gestão para criar uma experiência de alta qualidade. No final, irei apresentar os resultados de inquenritos realizados no hostel. Depois de 6 meses os impactos dos eventos são muito visíveis nas avaliações e comentários dos hospedes, assim como na satisfação da equipe e nos lucros das vendas

Discovery of strongly blue shifted mid-infrared [NeIII] and [NeV] emission in ULIRGs

We report the discovery of blue shifted (delta(V) > 200 km/s) mid-infrared [NeIII] and/or [NeV] emission in 25 out of 82 ULIRGs (30% of our sample). The incidence of blue shifted [NeV] emission is even higher (59%) among the sources with a [NeV] detection -- the tell-tale signature of an active galactic nucleus (AGN). Sixteen ULIRGs in our sample, eleven of which are optically classified as AGN, have [NeIII] blue shifts above 200 km/s. A comparison of the line profiles of their 12.81um [NeII], 15.56um [NeIII] and 14.32um [NeV] lines reveals the ionization of the blue shifted gas to increase with blue shift, implying decelerating outflows in a stratified medium, photo-ionized by the AGN. The strong correlation of the line width of the [NeIII] line with the radio luminosity indicates that interaction of expanding radio jets with the dense ISM surrounding the AGN may explain the observed neon line kinematics for the strongest radio sources in this sample.Comment: Accepted for publication by ApJ Letters. 15 pages, 4 figure

Bimodal AGNs in Bimodal Galaxies

By their star content, the galaxies split out into a red and a blue population; their color index peaked around u-r=2.5 or u-r=1, respectively, quantifies the ratio of the blue stars newly formed from cold galactic gas, to the redder ones left over by past generations. On the other hand, upon accreting substantial gas amounts the central massive black holes energize active galactic nuclei (AGNs); here we investigate whether these show a similar, and possibly related, bimodal partition as for current accretion activity relative to the past. To this aim we use an updated semianalytic model; based on Monte Carlo simulations, this follows with a large statistics the galaxy assemblage, the star generations and the black hole accretions in the cosmological framework over the redshift span from z=10 to z=0. We test our simulations for yielding in close detail the observed split of galaxies into a red, early and a blue, late population. We find that the black hole accretion activities likewise give rise to two source populations: early, bright quasars and later, dimmer AGNs. We predict for their Eddington parameter $\lambda_E$ -- the ratio of the current to the past black hole accretions -- a bimodal distribution; the two branches sit now under $\lambda_E \approx 0.01$ (mainly contributed by low-luminosity AGNs) and around $\lambda_E \approx 0.3-1$. These not only mark out the two populations of AGNs, but also will turn out to correlate strongly with the red or blue color of their host galaxies.Comment: 7 pages, accepted for publication in the Astrophysical Journa

Molecular line profiles as diagnostics of protostellar collapse: modelling the `blue asymmetry' in inside-out infall

The evolution of star-forming core analogues undergoing inside-out collapse is studied with a multi-point chemodynamical model which self-consistently computes the abundance distribution of chemical species in the core. For several collapse periods the output chemistry of infall tracer species such as HCO+, CS, and N2H+, is then coupled to an accelerated Lambda-iteration radiative transfer code, which predicts the emerging molecular line profiles using two different input gas/dust temperature distributions. We investigate the sensitivity of the predicted spectral line profiles and line asymmetry ratios to the core temperature distribution, the time-dependent model chemistry, as well as to ad hoc abundance distributions. The line asymmetry is found to be strongly dependent on the adopted chemical abundance distribution. In general, models with a warm central region show higher values of blue asymmetry in optically thick HCO+ and CS lines than models with a starless core temperature profile. We find that in the formal context of Shu-type inside-out infall, and in the absence of rotation or outflows, the relative blue asymmetry of certain HCO+ and CS transitions is a function of time and, subject to the foregoing caveats, can act as a collapse chronometer. The sensitivity of simulated HCO+ line profiles to linear radial variations, subsonic or supersonic, of the internal turbulence field is investigated in the separate case of static cores.Comment: Accepted to MNRAS; 20 pages, 13 fig

Effects of dislocation density on injection and temperature sensitivity of InGaN LED emission spectra: a combined experimental and simulation approach

The aim of this paper is to describe a combined simulation and characterization activity carried out on blue LEDs grown on templates with different threading dislocation densities (TDDs)