A Peculiar Broad Line Radio Galaxy 1938-155： VLA Observation at 90 cm     

Tao An  Xiao-Yu Hong  Wen-Xia Feng  Jun-Hui Zhao Shanghai Astronomical Observatory  Chinese Academy of Sciences  Shanghai  National Astronomical Observatories  Chinese Academy of Sciences  Beijing Harvard-Smithsonian Center for Astrophysics  Garden Street  MS  Cambridge  MA 《中国天文和天体物理学报》2004,4(6):527-532

We observed 1938-155, a broad line radio galaxy (BLRG), with the Very Large Array (VLA) at 90cm with an angular resolution of 6.8" × 4.0". The source consists of two components separated by 4 arcsec (- 20kpc, for H0 = 65km s-1 Mpc-1, q0 = 0.5) along the SE-NW direction. Both components show steep-spectra with a similar spectral index α - 0.83 ± 0.07 (Sv ∝ v-α). The bright double components are surrounded by a low-brightness cocoon. The radio properties of the two bright components are consistent with the hot spots produced by twin jets. An upper limit of - 0.0008 for the core dominance parameter (R) is inferred, suggesting there is no prominent radio core in the source. Assuming a modest viewing angle 30f77, a jet velocity is estimated - 0.07 c, based on the jet to counter-jet brightness ratio (J). The lower limit in jet speed inferred is consistent with no Doppler beaming effect on the jet. The radio galaxy 1938-155 could be an exceptional BLRG with no prominent radio core or jet.  相似文献   

Quaternary turbidite systems on the northern margins of the Balearic Basin (Western Mediterranean): a synthesis   总被引：1，自引：1，他引：1  

L. Droz  A. T. dos Reis  M. Rabineau  S. Berné  G. Bellaiche 《Geo-Marine Letters》2006,26(6):347-359

The Balearic Basin is a young basin composed of thick Plio–Quaternary sediments, including active gravity sedimentation. During the Quaternary, gravity processes deposited (1) turbidite systems, either as symmetrical fans (Petit-Rhône and Valencia fans) or asymmetrical ridges (Marseille–Planier, Grand-Rhône and Pyreneo-Languedocian ridges) and (2) several mass-transport deposits, indicating recurrent sedimentary failures of the margin. This paper synthesizes previous works and proposes a chronological sedimentary evolution for the basin. Except for the last 20 ka, the chronostratigraphy remains poorly constrained but should soon be established for the last 500 ka, based on the PROMESS1 drillings on the outer shelf of the Gulf of Lions, and hopefully for the last 30 Ma, based on ultra-deep drilling in the deep basin from aboard the Chikyu research vessel (IODP proposal Pre699).  相似文献   

Stratigraphy and allogenic controls of the western Portugal Cretaceous: an updated synthesis     

J.L. Dinis  J. Rey  P.P. Cunha  P. Callapez  R. Pena dos Reis 《Cretaceous Research》2008,29(5-6):772

The stratigraphy of the western Portugal on-shore Cretaceous record (western Iberian margin, Lusitanian Basin) is described, including formal units and a selection of informal units prevailing in the geological literature. This paper is a synthesis based on a review of previous works, but with an innovative emphasis on the interpretation of eustatic and tectonic controls. The sedimentary record is dominated by siliciclastics and comprises fluvial and deltaic coastal marine siliciclastic systems, as well as extensive deposits of shallow marine carbonate platforms, both open and rimmed. Several regional unconformities and transgressive/regressive cycles are identified and the allogenic controls interpreted, namely the geodynamic events along the boundaries of the Iberian plate. Above the Berriasian deposits belonging to the Upper Jurassic cycle, the five main unconformity-bounded units are: (1) upper Berriasian–lower Barremian, (2) upper Barremian–lower Aptian, (3) upper Aptian–uppermost Cenomanian, (4) mid lower Turonian–lower Campanian and (5) middle Campanian–Maastrichtian. These units show transgressive peaks in the lower Hauterivian, lower Aptian, base of the upper Cenomanian and mid lower Turonian. The general trend of the Lower Cretaceous reflects the transition from late rifting to passive margin, with the last break-up unconformity dated as late Aptian. The Lusitanian Basin achieved full infill by the Cenomanian, when a large carbonate platform extended far inland. The later deposits were preserved only in the northern sector and the accompanying unconformities reflect transpressive intraplate stresses generated in boundaries of the plate with Africa and Eurasia. With very low accommodation being created throughout the Late Cretaceous, fluvial deposits were dominant, including a few marine levels related with eustatic rises in the early Turonian, the Coniacian, the early Campanian and the Maastrichtian.  相似文献   

Expert views - and disagreements - about the potential of energy technology R&D     

Laura Diaz Anadon  Erin Baker  Valentina Bosetti  Lara Aleluia Reis 《Climatic change》2016,136(3-4):677-691

Mitigating climate change will require innovation in energy technologies. Policy makers are faced with the question of how to promote this innovation, and whether to focus on a few technologies or to spread their bets. We present results on the extent to which public R&D might shape the future cost of energy technologies by 2030. We bring together three major expert elicitation efforts carried out by researchers at UMass Amherst, Harvard, and FEEM, covering nuclear, solar, Carbon Capture and Storage (CCS), bioelectricity, and biofuels. The results show experts believe that there will be cost reductions resulting from R&D and report median cost reductions around 20 % for most of the technologies at the R&D budgets considered. Although the improvements associated to solar and CCS R&D show some promise, the lack of consensus across studies, and the larger magnitude of the R&D investment involved in these technologies, calls for caution when defining what technologies would benefit the most from additional public R&D. In order to make R&D funding decisions to meet particular goals, such as mitigating climate change or improving energy security, or to estimate the social returns to R&D, policy makers need to combine the information provided in this study on cost reduction potentials with an analysis of the macroeconomic implications of these technological changes. We conclude with recommendations for future directions on energy expert elicitations.  相似文献   

Development of a drought vulnerability index using MCDM and GIS: study case in São Paulo and Ceará, Brazil     

de Azevedo Reis  Gabriela  de Souza Filho  Francisco Assis  Nelson  Donald Robert  Rocha  Renan Vieira  da Silva  Samiria Maria Oliveira 《Natural Hazards》2020,104(2):1781-1799

Natural Hazards - Although climate change vulnerability research in general has increased over the last decade, Latin American countries have more directed more limited efforts toward vulnerability...  相似文献   

Observation of Conditions Preceding Peak Indoor Air Volatile Organic Compound Concentrations in Vapor Intrusion Studies     

Chris Lutes  Chase Holton  Brian Schumacher  John Zimmerman  Andrew Kondash  Robert Truesdale MS  AB. 《Ground Water Monitoring & Remediation》2021,41(2):99-111

Temporal and spatial variability of indoor air volatile organic compound (VOC) concentrations can complicate vapor intrusion (VI) assessment and decision-making. Indicators and tracers (I&T) of VI, such as differential temperature, differential pressure, and indoor radon concentration, are low-cost lines of evidence to support sampling scheduling and interpretation of indoor air VOC sampling results. This study compares peak indoor air chlorinated VOC concentrations and I&T conditions before and during those peak events at five VI sites. The sites differ geographically and in their VI conceptual site models (CSM). Relative to site-specific baseline values, the results show that cold or falling outdoor temperatures, rising cross slab differential pressures, and increasing indoor radon concentrations can predict peak VOC concentrations. However, cold outdoor air temperature was not useful at one site where elevated shallow soil temperature was a better predictor. Correlations of peak VOC concentrations to elevated or rising barometric pressure and low wind speed were also observed with some exceptions. This study shows how the independent variables that control or predict peak indoor air VOC concentrations are specific to building types, climates, and VI CSMs. More I&T measurements at VI sites are needed to identify scenario-specific baseline and peak related I&T conditions to improve decision-making.  相似文献   

Performance evaluation of AR5-CMIP5 models for the representation of seasonal and multi-annual variability of precipitation in Brazilian hydropower sector basins under RCP8.5 scenario     

Cleiton Da Silva Silveira  Francisco Das Chagas Vasconcelos Junior  Francisco De Assis De Souza Filho  Sullyandro Oliveira Guimarães  Antonio Duarte Marcos Junior  Giullian Nicola Lima Dos Reis 《水文科学杂志》2013,58(11):1279-1296

ABSTRACT

Representations of precipitation from CMIP5 models over the 1950–1999 period in hydrographic basins that are relevant to the Brazilian electricity sector are evaluated in this study. The majority of ensemble members adequately represented seasonal variability, although they differed about the patterns of high-frequency interannual variation. The models did not adequately represent seasonal-scale precipitation in the southern region of Brazil. Relative to other models, the CNRM_CM5 and HadGEM2-ES models demonstrated good seasonal and interannual representation over most basins, while the global CanESM2, GFDL-ESM2M and IPSL_CM5A-LR models demonstrated relatively poor performance. The models concur on the impact of the RCP8.5 scenario in the Southeast/Midwest and South sectors over the period 2015–2044, suggesting that precipitation will decrease up to 15% in the basin supplying the Furnas hydropower plant and by 12% in the basin supplying the Itaipú plant, which represents 25% of the hydroelectric production in Brazil.  相似文献   

The use of multivariate statistical analysis of geochemical data for assessing the spatial distribution of soil contamination by potentially toxic elements in the Aljustrel mining area (Iberian Pyrite Belt,Portugal)   总被引：1，自引：1，他引：0  

C. Candeias  E. Ferreira da Silva  A. R. Salgueiro  H. G. Pereira  A. P. Reis  C. Patinha  J. X. Matos  P. H. Ávila 《Environmental Earth Sciences》2011,62(7):1461-1479

Aljustrel mine is located in SW Portugal, in the western sector of the Iberian Pyrite Belt. The Aljustrel village was developed around the exploitations of massive polymetallic sulphides that occur in the area (4 orebodies mined, 2 in exploration phase). The pyrite ore was extensively exploited from 1850 to 1993, when production was discontinued. A mining restart occurred in 2008, only during a few months. The objectives of the study were to assess the levels of soil contamination, to determine associations between the different chemical elements and their spatial distribution, as well as to identify possible sources of contamination that can explain the spatial patterns of soil pollution in the area. Principal component analysis combined with spatial interpretation successfully grouped the elements according to their sources and provided evidence about their geogenic or anthropogenic origin. From this study, it is possible to conclude that soils around Algares/Feitais tailing deposits, Estéreis and Águas Claras mine dams and S. João mine show severe contamination. The highest concentrations of As (up to 3,936 mg kg^?1) and certain heavy metals (up to 321.7 mg kg^?1 for Bi, 5,414 mg kg^?1 for Cu, 20,000 mg kg^?1 for Pb, 980.6 mg kg^?1 for Sb, and 22 mg kg^?1 Cd) were obtained near Algares area while the highest concentration of Cd (up to 61.6 mg kg^?1) and Zn (up to 20,000 mg kg^?1) were registered in samples collected in the S. João area. The highest pollution load index (>4.0) was recorded at the Algares area where the metal concentrations exceed typical soil background levels by as much as two orders of magnitude.  相似文献   

Fatty acid profiles indicate the habitat of mud snails Hydrobia ulvae within the same estuary: Mudflats vs. seagrass meadows     

Helena Coelho  Teresa Lopes da Silva  Alberto Reis  Henrique Queiroga  João Serôdio  Ricardo Calado 《Estuarine, Coastal and Shelf Science》2011

Mud snails Hydrobia ulvae occupy different habitats in complex estuarine ecosystems. In order to determine if fatty acid profiles displayed by mud snails can be used to identify the habitat that they occupy within the same estuary, fatty acids of H. ulvae from one mudflat and one seagrass meadow in the Ria de Aveiro (Portugal) were analyzed and compared to those displayed by microphytobenthos (MPB), the green leaves (epiphyte-free) of Zostera noltii, as well as those exhibited by the epiphytic community colonizing this seagrass. MPB and epiphytic diatom-dominated samples displayed characteristic fatty acids, such as 16:1n-7 and 20:5n-3, while 18:2n-6 and 18:3n-3 were the dominant fatty acids in the green leaves of Z. noltii. Significant differences between the fatty acid profiles of H. ulvae specimens sampled in the mudflat and the seagrass meadow could be identified, with those from the mudflat displaying higher levels of fatty acids known to be characteristic of MPB. This result points towards the well known existence of grazing activity on MPB by mud snails. The fatty acid profiles displayed by H. ulvae inhabiting the seagrass meadows show no evidence of direct bioaccumulation of the two most abundant polyunsaturated fatty acids of Z. noltii (18:2n-6 and 18:3n-3) in the mud snails, which probably indicates that either these compounds can be metabolized to produce energy, used as precursors for the synthesis of essential fatty acids, or that the snails do not consume seagrass leaves at all. Moreover, the fatty acid profiles of mud snails inhabiting the seagrass meadows revealed the existence of substantial inputs from microalgae, suggesting that the epiphytic community colonizing the leaves of Z. noltii displays an important role on the diet of these organisms. This assumption is supported by the high levels of 20:5n-3 and 22:6n-3 recorded in mud snails sampled from seagrass meadows. In conclusion, fatty acid analyses of H. ulvae can be successfully used to identify the habitat occupied by these organisms within the same estuary (e.g. mudflats and seagrass meadows) and reveal the existence of contrasting dietary regimes.  相似文献   

Barnacles as biomonitors of metal contamination in coastal waters     

Pedro A. Reis  Maria Antónia Salgado  Vitor Vasconcelos 《Estuarine, Coastal and Shelf Science》2011

The use of barnacles as biomonitors of metal contamination in coastal waters worldwide is reviewed as a critique compilation of the reported studies and presents resume-tables of available data for future reference. The barnacle body reflects both short and long-term metal level environmental variations and the metal bioaccumulation occurs mainly in their granules (relatively inactive pools). The barnacle body is considered as good biomonitoring material and different barnacle species could bioaccumulate metal concentration ranges of 40–153,000 μg/g of Zn, 20–22,230 μg/g de Fe, 1.5–21,800 μg/g of Cu, 5.9–4742 μg/g of Mn, 0.1–1000 μg/g of Pb, 0.7–330 μg/g of Cd, 0.4–99 μg/g of Ni and 0.2–49 μg/g of Cr. However, as the plates (‘shells’) of barnacle exoskeletons can be affected by metal levels in coastal waters, mainly in their composition and morphology, they are not considered good biomonitoring material. Despite this, the use of a specific barnacle species or group of species in a specific region must firstly be carefully validated and the interpretation of the contaminant bioaccumulation levels should involve specific environmental variations of the region, physiological parameters of the barnacle species and the relationship between the potential toxicity of the contaminant for the environment and their significance for the barnacle species. Barnacles, particularly a widespread cosmopolitan species such as Amphibalanus amphitrite, have a great potential as biomonitors of anthropogenic contamination in coastal waters and have been used worldwide, including Europe (United Kingdom, Turkey, Poland, Croatia, Spain and Portugal), Asia (India and China), Oceania (Australia), North America (Florida, Massachusetts and Mexico) and South America (Brazil). The use of barnacle species as biomonitors of metal contamination in coastal waters is considered an important and valuable tool to evaluate and predict the ecological quality of an ecosystem.  相似文献