Nunca mais voltas ao Cais? Percepções sociais e políticas sobre os Cais da Ria de Aveiro

As comunidades existentes em torno da Ria de Aveiro sempre mantiveram com esta uma forte afinidade. Este ecossistema foi sempre utilizado como fonte de recursos, sendo que as populações mais ribeirinhas viviam em função do que a “Ria” lhes concedia – o sal, o moliço, a pesca, o transporte lagunar e mesmo a agricultura. Por esta razão, foram construídos vários cais de acostagem que serviam de suporte às diversas actividades que aí se desenvolviam. Com o desaparecimento/desvalorização de determinadas actividades, muitos destes cais foram perdendo a sua vitalidade, encontrando-se de momento em forte estado de degradação e contribuindo para o continuado abandono destas áreas que, por sua vez, tem implicações quer na estrutura socioeconómica das comunidades locais quer no próprio ecossistema. No sentido de recuperar e revalorizar os cais de acostagem, o programa Polis Litoral Ria de Aveiro, promoveu o Estudo de Caracterização para o Reordenamento e Valorização dos Núcleos Piscatórios Lagunares, focalizado sobre 22 cais dos municípios de Ovar, Estarreja, Murtosa, Aveiro, Ílhavo e Mira. Neste contexto foram analisados, a área de influência de cada cais, as actividades económicas e sociais presentes, bem como as potencialidades de desenvolvimento das actividades existentes

Caracterización de cepas de Bacillus thuringiensis berliner y actividad biológica hacia Spodoptera frugiperda (J. E. Smith) (Lepidoptera: noctuidae) y Anticarsia gemmatalis hübner (Lepidoptera: noctuidae).

RESUMEN: Se realizó la caracterización de nueve cepas cubanas de Bacillus thuringiensis según la morfología del cristal, la determinación del patrón de proteínas Cry y la actividad biológica frente a los insectos lepidópteros Spodoptera frugiperda y Anticarsia gemmatalis. Se observó la típica morfología bipiramidal en todas las cepas, y además la presencia de inclusiones cúbicas. El patrón de proteínas Cry obtenido correspondió con el de la cepa estándar internacional de B. thuringiensis var. kurstaki cepa HD1, en el que se observan dos bandas bien definidas correspondientes a la proteína Cry 1 (130 kDa) y Cry 2 (70 kDa). En la evaluación de la actividad biológica las cepas LBT 4 y LBT 7 causaron el 100% de mortalidad frente a S. frugiperda, mientras que las LBT 4, LBT 7, LBT 13 y LBT 47 provocaron el 100% de mortalidad para A. gemmatalis. abstract: This study describes the characterization of nine Cuban Bacillus thuringiensis strains based on crystal morphology, SDS polyacrylamide electrophoresis (PAGE) and insecticidal activity against Spodoptera frugiperda and Anticarsia gemmatalis. Ultrastructural analysis of parasporal bodies of the nine strains showed the typical bipyramidal crystal and cubic inclusion partially embedded in the middle of the bipyramidal crystal. The PAGE analysis showed two bands of 130 kDa and 70 kDa belongs to Cry 1 and Cry 2 protein present to HD1 standard strains B. thuringiensis var. kurstaki. The strains LBT 4 and LBT 7 analyzed in this report showed potential as biological insecticide against S. frugiperda and LBT 4, LBT 7, LBT13 and LBT47 strains showed 100% of mortality to Anticarsia gemmatalis

Testing a prediction of the merger origin of early-type galaxies: a correlation between stellar populations and asymmetry

One of the key predictions of the merger hypothesis for the origin of early-type (elliptical and lenticular) galaxies is that tidally-induced asymmetric structure should correlate with signatures of a relatively young stellar population. Such a signature was found by Schweizer and Seitzer (1992; AJ, 104, 1039) at roughly 4sigma confidence. In this paper, we revisit this issue with a nearly ten-fold larger sample of 0.01<z<0.03 galaxies selected from the Two Micron All-Sky Survey and the Sloan Digital Sky Survey. We parameterize tidal structure using a repeatable algorithmic measure of asymmetry, and correlate this with color offset from the early-type galaxy color-magnitude relation. We recover the color offset-asymmetry correlation; furthermore, we demonstrate observationally for the first time that this effect is driven by a highly-significant trend towards younger ages at higher asymmetry values. We present a simple model for the evolution of early-type galaxies through gas-rich major and minor mergers that reproduces their observed build-up from z=1 to the present day and the distribution of present-day colors and ages. We show using this model that if both stellar populations and asymmetry were ideal `clocks' measuring the time since last major or minor gas-rich interaction, then we would expect a rather tight correlation between age and asymmetry. We suggest that the source of extra scatter is natural diversity in progenitor star formation history, gas content, and merger mass ratio, but quantitative confirmation of this conjecture will require sophisticated modeling. We conclude that the asymmetry-age correlation is in basic accord with the merger hypothesis, and indicates that an important fraction of the early-type galaxy population is affected by major or minor mergers at cosmologically-recent times.Comment: Astrophysical Journal, in press. 20 pages, 18 figure

The Majority of Compact Massive Galaxies at z~2 are Disk Dominated

We investigate the stellar structure of massive, quiescent galaxies at z~2, based on Hubble Space Telescope/WFC3 imaging from the Early Release Science program. Our sample of 14 galaxies has stellar masses of M* > 10^{10.8} Msol and photometric redshifts of 1.5 < z < 2.5. In agreement with previous work, their half-light radii are <2 kpc, much smaller than equally massive galaxies in the present-day universe. A significant subset of the sample appears highly flattened in projection, which implies, considering viewing angle statistics, that a significant fraction of the galaxies in our sample have pronounced disks. This is corroborated by two-dimensional surface brightness profile fits. We estimate that 65% +/- 15% of the population of massive, quiescent z~2 galaxies are disk-dominated. The median disk scale length is 1.5 kpc, substantially smaller than the disks of equally massive galaxies in the present-day universe. Our results provide strong observational evidence that the much-discussed ultra-dense high-redshift galaxies should generally be thought of as disk-like stellar systems with the majority of stars formed from gas that had time to settle into a disk.Comment: published versio

Obscured star formation in intermediate-density environments:A Spitzer study of the Abell 901/902 supercluster

We explore the amount of obscured star formation as a function of environment in the Abell 901/902 (A901/902) supercluster at z = 0.165 in conjunction with a field sample drawn from the A901 and CDFS fields, imaged with the Hubble Space Telescope as part of the Space Telescope A901/902 Galaxy Evolution Survey and Galaxy Evolution from Morphology and Spectral Energy Distributions (SEDs) Survey. We combine the combo-17 near-UV/optical SED with Spitzer 24 mu m photometry to estimate both the unobscured and obscured star formation in galaxies with M-* > 10(10) M-circle dot. We find that the star formation activity in massive galaxies is suppressed in dense environments, in agreement with previous studies. Yet, nearly 40% of the star-forming (SF) galaxies have red optical colors at intermediate and high densities. These red systems are not starbursting; they have star formation rates (SFRs) per unit stellar mass similar to or lower than blue SF galaxies. More than half of the red SF galaxies have low infrared-to-ultraviolet (IR-to-UV) luminosity ratios, relatively high Sersicindices, and they are equally abundant at all densities. They might be gradually quenching their star formation, possibly but not necessarily under the influence of gas-removing environmental processes. The other greater than or similar to 40% of the red SF galaxies have high IR-to-UV luminosity ratios, indicative of high dust obscuration. They have relatively high specific SFRs and are more abundant at intermediate densities. Our results indicate that while there is an overall suppression in the SF galaxy fraction with density, the small amount of star formation surviving the cluster environment is to a large extent obscured, suggesting that environmental interactions trigger a phase of obscured star formation, before complete quenching

Dust-Obscured Star-Formation in Intermediate Redshift Galaxy Clusters

We present Spitzer MIPS 24-micron observations of 16 0.4<z<0.8 galaxy clusters drawn from the ESO Distant Cluster Survey (EDisCS). This is the first large 24-micron survey of clusters at intermediate redshift. The depth of our imaging corresponds to a total IR luminosity of 8x10^10 Lsun, just below the luminosity of luminous infrared galaxies (LIRGs), and 6^{+1}_{-1}% of M_V < -19 cluster members show 24-micron emission at or above this level. We compare with a large sample of coeval field galaxies and find that while the fraction of cluster LIRGs lies significantly below that of the field, the IR luminosities of the field and cluster galaxies are consistent. However, the stellar masses of the EDisCS LIRGs are systematically higher than those of the field LIRGs. A comparison with optical data reveals that ~80% of cluster LIRGs are blue and the remaining 20% lie on the red sequence. Of LIRGs with optical spectra, 88^{+4}_{-5}% show [O II] emission with EW([O II])>5A, and ~75% exhibit optical signatures of dusty starbursts. On average, the fraction of cluster LIRGs increases with projected cluster-centric radius but remains systematically lower than the field fraction over the area probed (< 1.5xR200). The amount of obscured star formation declines significantly over the 2.4 Gyr interval spanned by the EDisCS sample, and the rate of decline is the same for the cluster and field populations. Our results are consistent with an exponentially declining LIRG fraction, with the decline in the field delayed by ~1 Gyr relative to the clusters.Comment: 15 pages, 9 figure

What turns galaxies off? The different morphologies of star-forming and quiescent galaxies since z~2 from CANDELS

We use HST/WFC3 imaging from the CANDELS Multicycle Treasury Survey, in conjunction with the Sloan Digital Sky Survey, to explore the evolution of galactic structure for galaxies with stellar masses >3e10M_sun from z=2.2 to the present epoch, a time span of 10Gyr. We explore the relationship between rest-frame optical color, stellar mass, star formation activity and galaxy structure. We confirm the dramatic increase from z=2.2 to the present day in the number density of non-star-forming galaxies above 3e10M_sun reported by others. We further find that the vast majority of these quiescent systems have concentrated light profiles, as parametrized by the Sersic index, and the population of concentrated galaxies grows similarly rapidly. We examine the joint distribution of star formation activity, Sersic index, stellar mass, inferred velocity dispersion, and stellar surface density. Quiescence correlates poorly with stellar mass at all z<2.2. Quiescence correlates well with Sersic index at all redshifts. Quiescence correlates well with `velocity dispersion' and stellar surface density at z>1.3, and somewhat less well at lower redshifts. Yet, there is significant scatter between quiescence and galaxy structure: while the vast majority of quiescent galaxies have prominent bulges, many of them have significant disks, and a number of bulge-dominated galaxies have significant star formation. Noting the rarity of quiescent galaxies without prominent bulges, we argue that a prominent bulge (and perhaps, by association, a supermassive black hole) is an important condition for quenching star formation on galactic scales over the last 10Gyr, in qualitative agreement with the AGN feedback paradigm.Comment: The Astrophysical Journal, in press; 20 pages with 13 figure