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91.
R. Rampazzo P. Mazzei A. Marino L. Bianchi H. Plana G. Trinchieri M. Uslenghi A. Wolter 《Astrophysics and Space Science》2018,363(4):80
The ultraviolet–optical colour magnitude diagram of rich galaxy groups is characterised by a well developed Red Sequence, a Blue Cloud and the so-called Green Valley. Loose, less evolved groups of galaxies which are probably not virialised yet may lack a well defined Red Sequence. This is actually explained in the framework of galaxy evolution. We are focussing on understanding galaxy migration towards the Red Sequence, checking for signatures of such a transition in their photometric and morphological properties. We report on the ultraviolet properties of a sample of early-type (ellipticals+S0s) galaxies inhabiting the Red Sequence. The analysis of their structures, as derived by fitting a Sérsic law to their ultraviolet luminosity profiles, suggests the presence of an underlying disk. This is the hallmark of dissipation processes that still must have a role to play in the evolution of this class of galaxies. Smooth particle hydrodynamic simulations with chemo-photometric implementations able to match the global properties of our targets are used to derive their evolutionary paths through ultraviolet–optical colour magnitude diagrams, providing some fundamental information such as the crossing time through the Green Valley, which depends on their luminosity. The transition from the Blue Cloud to the Red Sequence takes several Gyrs, being about 3–5 Gyr for the brightest galaxies and longer for fainter ones, if occurring.The photometric study of nearby galaxy structures in the ultraviolet is seriously hampered by either the limited field of view of the cameras (e.g., in Hubble Space Telescope) or by the low spatial resolution of the images (e.g., in the Galaxy Evolution Explorer). Current missions equipped with telescopes and cameras sensitive to ultraviolet wavelengths, such as Swift-UVOT and Astrosat-UVIT, provide a relatively large field of view and a better resolution than the Galaxy Evolution Explorer. More powerful ultraviolet instruments (size, resolution and field of view) are obviously bound to yield fundamental advances in the accuracy and depth of the surface photometry and in the characterisation of the galaxy environment. 相似文献
92.
Tiganadaba Lodoun Moussa Sanon Alessandra Giannini Pierre Sibiry Traoré Léopold Somé Jeanne Millogo Rasolodimby 《Theoretical and Applied Climatology》2014,117(3-4):485-494
In the Sahel region, seasonal predictions are crucial to alleviate the impacts of climate variability on populations' livelihoods. Agricultural planning (e.g., decisions about sowing date, fertilizer application date, and choice of crop or cultivar) is based on empirical predictive indices whose accuracy to date has not been scientifically proven. This paper attempts to statistically test whether the pattern of rainfall distribution over the May–July period contributes to predicting the real onset date and the nature (wet or dry) of the rainy season, as farmers believe. To that end, we considered historical records of daily rainfall from 51 stations spanning the period 1920–2008 and the different agro-climatic zones in Burkina Faso. We performed (1) principal component analysis to identify climatic zones, based on the patterns of intra-seasonal rainfall, (2) and linear discriminant analysis to find the best rainfall-based variables to distinguish between real and false onset dates of the rainy season, and between wet and dry seasons in each climatic zone. A total of nine climatic zones were identified in each of which, based on rainfall records from May to July, we derived linear discriminant functions to correctly predict the nature of a potential onset date of the rainy season (real or false) and that of the rainy season (dry or wet) in at least three cases out of five. These functions should contribute to alleviating the negative impacts of climate variability in the different climatic zones of Burkina Faso. 相似文献
93.
Anji Seth Sara A. Rauscher Maisa Rojas Alessandra Giannini Suzana J. Camargo 《Climatic change》2011,104(2):403-414
Twenty-first century climate model projections show an amplification of the annual cycle in tropical precipitation with increased
strength in both wet and dry seasons, but uncertainty is large and few studies have examined transition seasons. Here we analyze
coupled climate model projections of global land monsoons and show a redistribution of precipitation from spring to summer
in northern (North America, West Africa and Southeast Asia) and southern (South America, Southern Africa) regions. The annual
cycle changes are global in scale. Two mechanisms, remote (based on tropospheric stability) and local (based on low level
and surface moisture), are evaluated through the annual cycle. Increases in tropospheric stability persist from winter into
spring and are reinforced by a reduction in surface moisture conditions, suggesting that in spring both remote and local mechanisms
act to inhibit convection. This enhanced spring convective barrier leads to reduced early season rainfall; however, once sufficient
increases in moisture (by transport) are achieved, decreases in tropospheric stability result in increased precipitation during
the late rainy season. Further examination of this mechanism is needed in observations and models, as the projected changes
would have substantial implications for agriculture, water management, and disaster preparedness. 相似文献
94.
Thomas S. Bianchi Laura A. Wysocki Kathryn M. Schreiner Timothy R. Filley D. Reide Corbett Alexander S. Kolker 《Aquatic Geochemistry》2011,17(4-5):431-456
High sedimentation rates along river-dominated margins make these systems important repositories for organic carbon derived from both allochthonous and autochthonous sources. Using elemental carbon/nitrogen ratios, molecular biomarker (lignin phenol), and stable carbon isotopic (bulk and compound-specific) analyses, this study examined the sources of organic carbon to the Louisiana shelf within one of the primary dispersive pathways of the Mississippi River. Surface sediment samples were collected from stations across the inner, mid, and outer Louisiana shelf, within the Mississippi River plume region, during two cruises in the spring and fall of 2000. Lignin biomarker data showed spatial patterns in terrestrial source plant materials within the river plume, such that sediments near the mouth of the Mississippi River were comparatively less degraded and richer in C4 plant carbon than those found at mid-depth regions of the shelf. A molecular and stable isotope-based mixing model defining riverine, marsh, and marine organic carbon suggested that the highest organic carbon inputs to the shelf in spring were from marine sources (55?C61% marine organic carbon), while riverine organic carbon was the highest (63%) in fall, likely due to lower inputs of marine organic carbon at this time compared with the spring season. This model also indicated that marsh inputs, ranging from 19 to 34% and 3?C15% of the organic carbon in spring and fall, respectively, were significantly more important sources of organic carbon on the inner Louisiana shelf than previously suggested. Finally, we propose that the decomposition of terrestrial-derived organic carbon (from the river and local wetlands sources) in mobile muds may serve as a largely unexplored additional source of oxygen-consuming organic carbon in hypoxic bottom waters of the Louisiana shelf. 相似文献
95.
Shuiwang Duan Rainer Amon Thomas S. Bianchi Peter H. Santschi 《Estuaries and Coasts》2011,34(1):78-89
Soluble reactive phosphorus (SRP) has recently been shown to be one of the limiting nutrients for the growth of phytoplankton
in the northern Gulf of Mexico. We show here that during the past decade, SRP concentrations in the lower reaches of North
America's largest river, the Mississippi River, were highest in summer and lowest in winter and positively correlated with
water temperature. Upstream data showed this coupling to increase in a downstream trend in the Mississippi main stem. Water
quality data analysis and phosphorus mass balances were conducted to examine the controls of this relationship. The results
showed that the positive SRP–temperature correlation in the Mississippi River system was largely a result of gradual dilution
of SRP-enriched upper Mississippi River waters, which contributed most to the Mississippi River during summer, by SRP-depleted
waters from the Ohio and other tributaries. Particle buffering and organic matter mineralization might play a role in the
observed SRP–temperature relationship, but their importance relative to tributary effects is not quantified. Future work on
the seasonal dynamics of SRP in large river systems needs to consider the effects of both tributary dilution and in situ processes. 相似文献
96.
Raulin Jean Pierre Makhmutov Vladimir S. Kaufmann Pierre Pacini Alessandra Abe Lüthi Thomas Hudson Hugh S. Gary Dale E. 《Solar physics》2004,223(1-2):181-199
We present a report on the strong X5.3 solar flare which occurred on 25 August 2001, producing high-level γ-ray activity, nuclear lines and a dramatic long-duration white-light continuum. The bulk of millimeter radio fluxes reached a peak of ∼100 000 solar flux units at 89.4 GHz, and a few thousands of solar flux units were detected in the submillimeter range during the impulsive phase. In this paper we focus on and discuss (i) the implications inferred from high frequency radio observations during the impulsive phase; (ii) the dynamics of the low corona active region during the impulsive phase. In particular we found that 4–5 × 1036 accelerated (>20 keV) electrons s−1 radiating in a 1000–1100 G region, are needed to explain the millimeter to submillimeter-wave emissions. We present evidence that the magnetic field in the active region was very dynamic, and that strong non-thermal processes were triggered by the appearance of new, compact, low-lying (few thousand kilometers) loop systems, suggesting the acceleration site(s) were also located in the low solar atmosphere. 相似文献
97.
98.
Angélica Goldoni Camila Golfeto Jane B. Teixeira Gislaine Blumm Camila M. Wilhelm Franko Telöken Eloisa Bianchi Jairo L. Schmitt Günther Gehlen Marco Antonio S. Rodrigues Luciano Basso da Silva 《Environmental Earth Sciences》2014,72(5):1503-1509
This study was conducted to evaluate the chemical parameters and the cytotoxic and genotoxic potential of raw domestic sewage and effluents from treatment with activated sludge and a floating emergent-macrophyte filter from a domestic wastewater treatment plant in the city of Novo Hamburgo, Rio Grande do Sul, Brazil. The physicochemical analysis revealed that both treatment systems achieved the legal emission pattern for biochemical oxygen demand, chemical oxygen demand, and suspended solids, but ammoniacal nitrogen and E. coli values were above the limits in the macrophyte treatment effluent. Phosphorous values were above the maximum permitted for both treatments. The results obtained from the Allium cepa test and the micronuclei test in fish did not demonstrate any significant differences in both cytotoxicity (mitotic index) and genotoxicity (chromosome aberration and micronucleus) endpoints between the negative control group and the exposed groups. However, the comet assay in fish revealed a DNA damage increase in animals exposed to the 30 % concentration of the macrophyte effluent and two concentrations of the activated sludge treatment effluent (10 and 75 %), which suggests that these two treatment systems may increase wastewater genotoxicity. 相似文献
99.
R. Rampazzo F. Annibali A. Marino L. Bianchi A. Bressan L. M. Buson M. Clemens P. Panuzzo W. W. Zeilinger 《Astrophysics and Space Science》2011,335(1):201-206
We detected recent star formation in nearby early-type galaxies located in low density environments, with GALEX Ultraviolet (UV) imaging. Signatures of star formation may be present in the nucleus and in outer rings/arm like structures.
Our study suggests that such star formation may be induced by different triggering mechanisms, such as the inner secular evolution
driven by bars, and minor accretion phenomena. We investigate the nature of the (FUV-NUV) color vs. Mg2 correlation, and suggest that it relates to “downsizing” in galaxy formation. 相似文献
100.
Thomas Monecke Sven Petersen Mark D. Hannington Marco Anzidei Alessandra Esposito Guido Giordano Dieter Garbe-Sch?nberg Nico Augustin Bernd Melchert Mike Hocking 《Bulletin of Volcanology》2012,74(9):1937-1944
Explosions of hot water, steam, and gas are common periodic events of subaerial geothermal systems. These highly destructive events may cause loss of life and substantial damage to infrastructure, especially in densely populated areas and where geothermal systems are actively exploited for energy. We report on the occurrence of a large number of explosion craters associated with the offshore venting of gas and thermal waters at the volcanic island of Panarea, Italy, demonstrating that violent explosions similar to those observed on land also are common in the shallow submarine environment. With diameters ranging from 5 to over 100?m, the observed circular seafloor depressions record a history of major gas explosions caused by frequent perturbation of the submarine geothermal system over the past 10,000?years. Estimates of the total gas flux indicate that the Panarea geothermal system released over 70?Mt of CO2 over this period of time, suggesting that CO2 venting at submerged arc volcanoes contributes significantly to the global atmospheric budget of this greenhouse gas. The findings at Panarea highlight that shallow submarine gas explosions represent a previously unrecognized volcanic hazard around populated volcanic islands that needs to be taken into account in the development of risk management strategies. 相似文献