Reef response to sea-level and environmental changes during the last deglaciation: Integrated Ocean Drilling Program Expedition 310, Tahiti Sea Level

The last deglaciation is characterized by a rapid sea-level rise and coeval abrupt environmental changes. The Barbados coral reef record suggests that this period has been punctuated by two brief intervals of accelerated melting (meltwater pulses, MWP), occurring at 14.08-13.61 ka and 11.4-11.1 ka (calendar years before present), that are superimposed on a smooth and continuous rise of sea level. Although their timing, magnitude, and even existence have been debated, those catastrophic sea-level rises are thought to have induced distinct reef drowning events. The reef response to sea-level and environmental changes during the last deglacial sea-level rise at Tahiti is reconstructed based on a chronological, sedimentological, and paleobiological study of cores drilled through the relict reef features on the modern forereef slopes during the Integrated Ocean Drilling Program Expedition 310, complemented by results on previous cores drilled through the Papeete reef. Reefs accreted continuously between 16 and 10 ka, mostly through aggradational processes, at growth rates averaging 10 mm yr-1. No cessation of reef growth, even temporary, has been evidenced during this period at Tahiti. Changes in the composition of coralgal assemblages coincide with abrupt variations in reef growth rates and characterize the response of the upward-growing reef pile to nonmonotonous sea-level rise and coeval environmental changes. The sea-level jump during MWP 1A, 16 ± 2 m of magnitude in ~350 yr, induced the retrogradation of shallow-water coral assemblages, gradual deepening, and incipient reef drowning. The Tahiti reef record does not support the occurrence of an abrupt reef drowning event coinciding with a sea-level pulse of ~15 m, and implies an apparent rise of 40 mm yr-1 during the time interval corresponding to MWP 1B at Barbados. © 2012 Geological Society of America

Weak Galactic Halo--Fornax dSph Connection from RR Lyrae Stars

For the first time accurate pulsation properties of the ancient variable stars of the Fornax dwarf spheroidal galaxy (dSph) are discussed in the broad context of galaxy formation and evolution. Homogeneous multi-band $BVI$ optical photometry of spanning {\it twenty} years has allowed us to identify and characterize more than 1400 RR Lyrae stars (RRLs) in this galaxy. Roughly 70\% are new discoveries. We investigate the period-amplitude distribution and find that Fornax shows a lack of High Amplitude (A_V\gsim0.75 mag) Short Period fundamental-mode RRLs (P\lsim0.48 d, HASPs). These objects occur in stellar populations more metal-rich than [Fe/H]$\sim$-1.5 and they are common in the Galactic halo (Halo) and in globulars. This evidence suggests that old (age older than 10 Gyr) Fornax stars are relatively metal-poor. A detailed statistical analysis of the role of the present-day Fornax dSph in reproducing the Halo period distribution shows that it can account for only a few to 20\% of the Halo when combined with RRLs in massive dwarf galaxies (Sagittarius dSph, Large Magellanic Cloud). This finding indicates that Fornax-like systems played a minor role in building up the Halo when compared with massive dwarfs. We also discuss the occurrence of HASPs in connection with the luminosity and the early chemical composition of nearby dwarf galaxies. We find that, independently of their individual star formation histories, bright (M_V\lsim-13.5 mag) galaxies have HASPs, whereas faint ones (M_V\gsim-11 mag) do not. Interestingly enough, Fornax belongs to a luminosity range (--11$<$M$_V<$--13.5 mag) in which the occurrence of HASPs appears to be correlated with the early star formation and chemical enrichment of the host galaxy.Comment: 7 pages, 5 figures, A&A, accepte

Influência de lâminas de irrigação na concentração da maturação de frutos de tomateiro.

O objetivo deste trabalho foi avaliar a influência de lâminas de irrigação sob o tamanho de frutos, na cultura do tomateiro para processamento industrial no municipio de Morrinhos-GO.Trabalho 26

Factors controlling spatio-temporal variation in carbon dioxide efflux from surface litter, roots, and soil organic matter at four rain forest sites in the eastern Amazon

[1] This study explored biotic and abiotic causes for spatio-temporal variation in soil respiration from surface litter, roots, and soil organic matter over one year at four rain forest sites with different vegetation structures and soil types in the eastern Amazon, Brazil. Estimated mean annual soil respiration varied between 13-17 t C ha(-1) yr(-1), which was partitioned into 0-2 t C ha(-1) yr(-1) from litter, 6-9 t C ha(-1) yr(-1) from roots, and 5-6 t C ha(-1) yr(-1) from soil organic matter. Litter contribution showed no clear seasonal change, though experimental precipitation exclusion over a one-hectare area was associated with a ten-fold reduction in litter respiration relative to unmodified sites. The estimated mean contribution of soil organic matter respiration fell from 49% during the wet season to 32% in the dry season, while root respiration contribution increased from 42% in the wet season to 61% during the dry season. Spatial variation in respiration from soil, litter, roots, and soil organic matter was not explained by volumetric soil moisture or temperature. Instead, spatial heterogeneity in litter and root mass accounted for 44% of observed spatial variation in soil respiration (p < 0.001). In particular, variation in litter respiration per unit mass and root mass accounted for much of the observed variation in respiration from litter and roots, respectively, and hence total soil respiration. This information about patterns of, and underlying controls on, respiration from different soil components should assist attempts to accurately model soil carbon dioxide fluxes over space and time

Impact of distance determinations on Galactic structure. II. Old tracers

Here we review the efforts of a number of recent results that use old tracers to understand the build up of the Galaxy. Details that lead directly to using these old tracers to measure distances are discussed. We concentrate on the following: (1) the structure and evolution of the Galactic bulge and inner Galaxy constrained from the dynamics of individual stars residing therein; (2) the spatial structure of the old Galactic bulge through photometric observations of RR Lyrae-type stars; (3) the three\--dimensional structure, stellar density, mass, chemical composition, and age of the Milky Way bulge as traced by its old stellar populations; (4) an overview of RR Lyrae stars known in the ultra-faint dwarfs and their relation to the Galactic halo; and (5) different approaches for estimating absolute and relative cluster ages.Comment: Review article, 80 pages (25 figures); Space Science Reviews, in press (chapter of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

Nilpotent Symmetries For Matter Fields In Non-Abelian Gauge Theory: Augmented Superfield Formalism

In the framework of superfield approach to Becchi-Rouet-Stora-Tyutin (BRST) formalism, the derivation of the (anti-)BRST nilpotent symmetries for the matter fields, present in any arbitrary interacting gauge theory, has been a long-standing problem. In our present investigation, the local, covariant, continuous and off-shell nilpotent (anti-)BRST symmetry transformations for the Dirac fields $(\psi, \bar\psi)$ are derived in the framework of the augmented superfield formulation where the four $(3 + 1)$-dimensional (4D) interacting non-Abelian gauge theory is considered on the six $(4 + 2)$-dimensional supermanifold parametrized by the four even spacetime coordinates $x^\mu$ and a couple of odd elements ($\theta$ and $\bar\theta$) of the Grassmann algebra. The requirement of the invariance of the matter (super)currents and the horizontality condition on the (super)manifolds leads to the derivation of the nilpotent symmetries for the matter fields as well as the gauge- and the (anti-)ghost fields of the theory in the general scheme of the augmented superfield formalism.Comment: LaTeX file, 16 pages, printing mistakes in the second paragraph of `Introduction' corrected, a footnote added, these modifications submitted as ``erratum'' to IJMPA in the final for