Signatures of recent star formation in ring S0 galaxies     

A. Marino  L. Bianchi  R. Rampazzo  D. Thilker  F. Annibali  A. Bressan  L. M. Buson 《Astrophysics and Space Science》2011,335(1):243-248

We present a study of the stellar populations of ring and/or arm-like structures in a sample of S0 galaxies using GALEX far- and near-ultraviolet imaging and SDSS optical data. Such structures are prominent in the UV and reveal recent star formation. We quantitatively characterize these rejuvenation events, estimating the average age and stellar mass of the ring structures, as well as of the entire galaxy. The mass fraction of the UV-bright rings is a few percent of the total galaxy mass, although the UV ring luminosity reaches 70% of the galaxy luminosity. The integrated colors of these S0s locates them in the red sequence (NGC 2962) and in the so-called green valley. We suggest that the star formation episodes may be induced by different triggering mechanisms, such as the inner secular evolution driven by bars, and interaction episodes.  相似文献   

Design method and behavior factor for steel frames with buckling restrained braces     

Melina Bosco  Edoardo M. Marino 《地震工程与结构动力学》2013,42(8):1243-1263

Buckling restrained braces (BRBs) are very effective in dissipating energy through stable tension–compression hysteretic cycles and have been successfully experimented in the seismic protection of buildings. Their behavior has been studied extensively in the last decades and today the level of performance guaranteed by these devices and the technological constrains that have to be fulfilled to optimize their behavior are well known. Furthermore, several companies in the world have developed their own BRBs and are now producing them. In spite of this, many seismic codes (for instance, the EuroCode 8) do not stipulate provisions for the design and construction of earthquake‐resistant structures equipped with BRBs. This discourages the structural engineering community from using these devices and seriously limits their use in structural applications. In this paper a procedure for the seismic design of steel frames equipped with BRBs is proposed. Furthermore, the paper presents a numerical investigation aimed at validating this design procedure and proposing the value of the behavior factor q that should be used for this structural type. To this end, a set of frames with BRBs is first designed by means of several values of q. Then, the obtained frames are subjected to a set of accelerograms compatible with the elastic response spectrum considered in design. The seismic response of the frames is determined by nonlinear dynamic analysis and represented in terms of the ductility demand of BRBs and the internal force demand of nondissipative members (beams and columns). Finally, the largest value of q that leads to acceptable seismic performance of the analyzed frames is assumed as adequate. The value of q is given in the paper as a continuous function of the assumed ductility capacity of the BRBs. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Low Ozone Episodes at Amphitrite Point Marine Boundary Layer Observatory,British Columbia,Canada     

Ian McKendry  Eric Christensen  Corinne Schiller  Roxanne Vingarzan  Anne Marie Macdonald  Yimei Li 《大气与海洋》2014,52(3):271-280

At Amphitrite Point, ozone (O₃) mixing ratios are observed to drop steadily to 5–15?ppb over a period of 12 hours or less with a frequency approaching one event per week (with highest frequencies occurring in summer and fall). Analysis of 47 such O₃ depletion events reveals that low O₃ episodes are a predominantly nocturnal phenomenon associated with anticyclonic conditions characterized by light onshore or alongshore winds and an absence of fog and mist. Back-trajectories show air carried to the Amphitrite Point Observatory (APO) during depletion events remains in the marine boundary layer and is not brought to the surface from aloft. There is no strong correlation with other “criteria” pollutants (CO, NO_x, SO₂, PM_2.5) that might be indicative of a mechanism for O₃ destruction linked to human, terrestrial, or marine pollutant sources. However, CO₂ mixing ratios are observed to increase, coincident with O₃ depletion. Together, these results point to a natural marine boundary layer phenomenon in which O₃ destruction dominates O₃ production and/or replenishment by vertical mixing. While there are several candidate mechanisms, the conditions for O₃ depletion (and CO₂ buildup) to occur are set by meteorology and, in particular, development of a stable marine boundary layer in which vertical mixing is suppressed. Support for this interpretation is provided by simultaneous increases in CO₂ in the stable marine boundary that are indicative of an important role played by marine biogenic processes (respiration). Future research should be directed at elucidating the chemical mechanisms responsible for O₃ destruction in the coastal zone, which means that there would be a need for a much broader range of measurements at APO (including halogenated species) as well as offshore measurements of both chemical and marine boundary layer meteorological variables.  相似文献   

Mine subsidence damage from room and pillar mining in Illinois   总被引：1，自引：0，他引：1  

Gennaro G. Marino  William Gamble 《Geotechnical and Geological Engineering》1986,4(2):129-150

Summary Data is presented on case histories of subsidence damage occurring over abandoned room and pillar mines in Illinois. The major modes of behaviour and damage in houses from sag-subsidence are described and summarized. The houses rested on crawl-space and basement foundations built from concrete and masonry. The prevalent mode of failure of bearing walls was inward bending. Failure is analysed and conventional design procedures are used to evaluate foundation failure.  相似文献   

Earthquake Damage Scenarios of the Building Stock of Potenza (Southern Italy) Including Site Effects   总被引：3，自引：0，他引：3  

Mauro Dolce  Angelo Masi  Maria Marino  Marco Vona 《Bulletin of Earthquake Engineering》2003,1(1):115-140

Damage scenarios relevant to the building stock of the town of Potenza, Southern Italy, are presented. A procedure for the preparation of scenarios has been purposely set up. In the first step, the inventory of the building stock has been made. Location and characteristics of buildings have been obtained from a survey carried out after the 1990 Potenza earthquake and further updated in 1999. In the second step, the absolute vulnerability of the buildings has been evaluated. A hybrid technique has been used, where typological analyses and expert judgement are combined together. Beyond the classes of vulnerability A, B and C of the MSK scale, the class D of EMS98 scale, for the less vulnerable buildings, has been considered. The third step has been the selection of the reference earthquakes by including also local amplification effects. Two events with 50 and 475 years return periods have been chosen as representative, respectively, of a damaging and of a destructive seismic event expected in Potenza. The sites that may exhibit important amplification effects have been identified using the first level method of the TC4 Manual. Damage scenarios of dwelling buildings have been prepared in the fourth step and reported in a GIS. They are relevant to the selected reference earthquakes, taking into account or not site effects. The generally low vulnerability of buildings results in a limited number of damaged buildings for the lower intensity earthquake, and of collapsed buildings, for the higher intensity earthquake. The influence of site effects on the damage distribution is significant. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Multi-objective assessment of conservation measures for the European eel (Anguilla anguilla): an application to the Camargue lagoons     

Bevacqua  Daniele; Melia  Paco; Crivelli  Alain J.; Gatto  Marino; De Leo  Giulio A. 《ICES Journal of Marine Science》2007,64(7):1483-1490

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Estimating Daily Egg Production of European Anchovy in the Adriatic Sea: A Critical Appraisal     

Paco Melià  Nicola Casavola  Marino Gatto 《Marine Ecology》2002,23(S1):272-279

Abstract. We discuss the critical problem of estimating daily egg production in the Daily Egg Production Method (DEPM), a widely used technique for the stock assessment of multiple spawning pelagic fishes. Data collected in 1999 for the stock of European anchovy ( Engraulis encrasicolus ) in the Southern Adriatic Sea are used to study the effects of different calibration techniques. We analyze the performances of the mortality model from which daily egg production is estimated. All these calibrations are based on the Bootstrap method. Nonlinear fitting (vs. linear regression on log-transformed data) is shown to guarantee more reliable parameter estimation. We show that specifying the function assigning age to staged eggs is crucial.  相似文献   

Nitrogen Retention in Salt Marsh Systems Across Nutrient-Enrichment,Elevation, and Precipitation Regimes: a Multiple-Stressor Experiment     

Autumn Oczkowski  Cathleen Wigand  Alana Hanson  Erin Markham  Kenneth M. Miller  Roxanne Johnson 《Estuaries and Coasts》2016,39(1):68-81

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The inverse problem and ground water management     

H. A. Loaiciga  M. A. Marino 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(3):161-168

The response of groundwater basins to natural and anthropogenic inputs depends on many interrelated factors such as the values of groundwater flow and mass transport parameters. This work presents a theoretical analysis of the impact of parameter uncertainty on groundwater management decisions. It is shown that under classical, Bayesian, and deterministic assumptions about the parameter structure, the resulting management decisions could be very different. This underscores the importance of adopting the proper parameter structure and the need for using consistent methods to solve the inverse problem.  相似文献   

Atmospheric oxygen exchange in the Hudson River: Dome measurements and comparison with other natural waters     

Roxanne Marino  Robert W. Howarth 《Estuaries and Coasts》1993,16(3):433-445

The measurement of metabolism using diel free-water oxygen techniques requires the estimation of atmospheric oxygen exchanges. We measured such exchange on nine different occasions in the freshwater, tidally-influenced Hudson River estuary using a floating dome technique. We also analyzed previously published data on the exchange of a variety of gases measured in lakes, estuaries, and open ocean waters using a wide variety of techniques. Data were expressed as a “transfer velocity” and normalized to an exchange of oxygen at 20°C. Considered together, these data indicate a significant predictive relationship when the natural log of transfer velocity is regressed with measured wind speed (r² = 0.55; p = 0.0001). The influence of wind was particularly pronounced in estuaries and in lakes. Data from open-ocean waters showed much less influence of wind, probably because surface turbulence in these deeper waters can be temporally and spatially decoupled from wind. Our Hudson data agreed well with data collected in other systems. In general, data from estuaries—including the Hudson—indicated slightly higher transfer velocities at any given wind speed than do data from lakes (although this difference was less pronounced for our Hudson data than for other estuaries). The difference may result from some interaction of wind and tidal currents, or it may reflect a bias in the dome method of measurements; all of the estuarine data were collected using the dome approach, while the majority of the lake data were determined using an added tracer. If the dome method actually gives a biased, high estimate of oxygen flux, this is in contradiction to previous criticisms of this method that domes may underestimate fluxes by blocking wind at the water surface. We have used the regression of the natural log of transfer velocity versus wind speed developed here to estimate respiration in the Hudson estuary from diel changes in dissolved oxygen. To allow for possible biases in technique and for measurement error, we estimated 95% confidence limits around the regression. Estimates of respiration in the Hudson determined using the upper and lower 95% confidence limits are 30% higher and 12% lower than that determined when using the best-fit regression. An independently-constrained carbon budget for the tidally-influenced, freshwater Hudson River estuary indicates that respiration rates cannot be much higher than our mean estimate as calculated using the linear regression of the gas transfer and wind data to correct for air-water oxygen exchange. Gas transfer in natural systems is difficult to measure and is controlled by many interrelated physical factors. In the absence of extensive, system-specific field studies, the regression presented here should be useful in estimating atmospheric oxygen exchange in other estuarine or riverine ecosystems which are relatively deep and wide.  相似文献