Ruprecht 55: an OB association at the edge of our Galaxy     

Guillermo Bosch  †‡  Rodolfo Barbá  ‡§  Nidia Morrell  †‡§  Virpi Niemela  †‡¶  Pablo Ostrov  ‡  Marcelo Arnal  §  Cristina Cappa  §  Ricardo Morras §  Guillermo Giménez de Castro 《Monthly notices of the Royal Astronomical Society》2003,341(1):169-178

We present new spectroscopy in the optical range and 21-cm H  i data covering the Ruprecht 55 (Ru 55) field in the Puppis window where several authors have proposed the existence of one (or two) clusters.
We have determined new MK spectral types for about 50 stars in the region, finding 43 OB-type stars among them. LS 985 was found to be an O9 V + O9.5 III binary and it is the earliest type of star in our observed sample.
We have identified a stellar OB association (Ru 55), which is most likely related to a depletion detected in our H  i data, as: (i) they are located at the same distance (6 kpc), within observational errors; (ii) both have similar radial velocities (∼67 km s⁻¹); (iii) current OB stars could have provided the energy needed to blow the cavity; (iv) the dynamical time-scale for the hole buildup matches the age estimated for the earliest OB stars; and (v) LS 985 might be responsible for ionizing the H  i cavity inner walls close to it.  相似文献   

Indenter-tectonics in the Philippines: Example from the Palawan Microcontinental Block - Philippine Mobile Belt Collision     

Graciano P. Yumul  Jr  Carla B. Dimalanta  Rodolfo A. Tamayo  Jr 《Resource Geology》2005,55(3):189-198

Abstract. The aseismic Palawan microcontinental block is an oceanic bathymetric high that has collided with the seismically-ac-tive Philippine Mobile Belt since the Early Miocene. Consequently, tectonic microblocks immediately north (Luzon) and south (Western Visayas Block) of the collision front rotated in opposite senses. The rotation led the microblocks to onramp adjacent strike-slip faults, and converted these to subduction zones, namely, the current Manila and Negros Trenches. In addition, the collision also initiated the southward propagation of a major left-lateral strike slip fault, the Philippine Fault Zone, and the Philippine Trench, which bounds the Philippine archipelago along its eastern boundary. Based on onshore and offshore data, the Philippine Fault Zone and the East Luzon Trough - Philippine Trench appears to also propagate northward. Furthermore, the opposite direction of propagation is also noted for the Manila and Negros Trenches from the locus of the collision in the Central Philippines to their northern and southern extensions, respectively. The ages of initiation of the Manila Trench (Early Miocene), Philippine Fault Zone (Middle Miocene) and Philippine Trench (Pliocene) as encountered along a west to east transect in the Central Philippines are consistent with the collision and subsequent indentation of Palawan with the rest of the Philippine Mobile Belt.  相似文献   

Biomonitoring of Trace Metals by Different species of Lichens (Parmelia) in North-West Italy     

Vincenzo Minganti  Renzo Capelli  Giuliana Drava  Rodolfo De Pellegrini  Giorgio Brunialti  Paolo Giordani  Paolo Modenesi 《Journal of Atmospheric Chemistry》2003,45(3):219-229

The concentrations of Cd, Cu, Mn, Ni, Pb, V, and Zn were measured in four different species of lichens (Parmelia caperata, P. pastillifera, P. saxatilis, P. sulcata) sampled in North-West Italy, in order to obtain maps showing metal distribution and the degree of deviation from background (natural) conditions. Significant differences among the species were found for Zn, Mn, Pb and V, suggesting that the combined use of mixed species in biomonitoring surveys can affect the interpretation of results. Results obtained for Parmelia caperata samples have been compared with background (natural) levels, and maps showing the distribution of each metal expressed as deviation from background levels have been obtained. Overall such maps show a medium to high alteration degree in the study area.  相似文献   

Collision, subduction and accretion events in the Philippines: A synthesis   总被引：7，自引：0，他引：7  

Graciano P. Yumul Jr  Carla B. Dimalanta  Rodolfo A. Tamayo Jr    Rene C. Maury 《Island Arc》2003,12(2):77-91

Abstract The Philippines preserves evidence of the superimposition of tectonic processes in ancient and present‐day collision and subduction zone complexes. The Baguio District in northern Luzon, the Palawan–Central Philippine region and the Mati–Pujada area in southeastern Mindanao resulted from events related to subduction polarity reversal leading to trench initiation, continent‐arc collision and autochthonous oceanic lithosphere emplacement, respectively. Geological data on the Baguio District in Northern Luzon reveal an Early Miocene trench initiation for the east‐dipping Manila Trench. This followed the Late Oligocene cessation of subduction along the west‐dipping proto‐East Luzon Trough. The Manila Trench initiation, which is modeled as a consequence of the counter‐clockwise rotation of Luzon, is attributed to the collision of the Palawan microcontinental block with the Philippine Mobile Belt. In the course of rotation, Luzon onramped the South China Sea crust, effectively converting the shear zone that bounded them into a subduction zone. Several collision‐related accretionary complexes (e.g. Romblon, Mindoro) are present in the Palawan–Central Philippine region. The easternmost collision zone boundary is located east of the Romblon group of islands. The Early Miocene southwestward shift of the collision boundary from Romblon to Mindoro started to end by the Pliocene. Continuous interaction between the Palawan microcontinental block and the Philippine Mobile Belt is presently taken up again along the collisional boundary east of the Romblon group of islands. The Mati–Pujada Peninsula area, on the other hand, is underlain by the Upper Cretaceous Pujada Ophiolite. This supra‐subduction zone ophiolite is capped by chert and pelagic limestones which suggests its derivation from a relatively deep marginal basin. The Pujada Ophiolite could be a part of a proto‐Molucca Sea plate. The re‐interpretation of the geology and tectonic settings of the three areas reaffirm the complex geodynamic evolution of the Philippine archipelago and addresses some of its perceived geological enigmas.  相似文献   

Correlation between ground failure and soil conditions in Adapazari, Turkey   总被引：4，自引：0，他引：4  

R. B. Sancio  J. D. Bray  J. P. Stewart  T. L. Youd  H. T. Durguno lu  Ak&#x;n nalp  R. B. Seed  C. Christensen  M. B. Baturay  T. Karaday&#x;lar 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1093-1102

Ground failure in Adapazari, Turkey during the 1999 Kocaeli earthquake (M_w=7.4) was severe. In four central downtown districts, where more than 1200 buildings collapsed or were heavily damaged, hundreds of structures tilted and penetrated into the ground due in part to liquefaction and ground softening. Based on a multi-institutional subsurface investigation program, soil conditions along four lines in which ground failure was surveyed after the earthquake are classified into four generalized subsurface site categories. This classification is primarily based on the presence or absence of shallow and intermediate depth liquefiable soils. Observations of ground failure are found to correlate well with site categories that are susceptible to liquefaction according to current state-of-the-art methods without strict adherence to the Chinese criteria. Soils that liquefied were found to meet the liquid limit and liquidity index conditions of the Chinese criteria. However, soils that liquefied did not typically meet the clay-size condition for liquefiable soils by the Chinese criteria.  相似文献   

CARBON EMISSIONS FROM MEXICAN FORESTS: CURRENT SITUATION AND LONG-TERM SCENARIOS   总被引：5，自引：0，他引：5  

Omar R. Masera  MARÍA J. ORDÓÑEZ  Rodolfo Dirzo 《Climatic change》1997,35(3):265-295

Estimates of carbon emissions from the forest sector in Mexico are derived for the year 1985 and for two contrasting scenarios in 2025. The analysis covers both tropical and temperate closed forests. In the mid-1980s, approximately 804,000 ha/year of closed forests suffered major perturbations, of which 668,000 ha was deforestation. Seventy-five percent of total deforestation is concentrated in tropical forests. The resulting annual carbon balance from land-use change is estimated at 67.0 × 10⁶ tons/year, which lead to net emissions of 52.3 × 10⁶ tons/year accounting for the carbon uptake in restoration plantations and degraded forest lands. This last figure represents approximately 40% of the country's estimated annual total carbon emissions for 1985–1987. The annual carbon balance from the forest sector in 2025 is expected to decline to 28.0 × 10⁶ t in the reference scenario and to become negative (i.e., a carbon sink), 62.0 × 10⁶ t in the policy scenario. A number of policy changes are identified that would help achieve the carbon sequestration potential identified in this last scenario.  相似文献   

Sea surface temperature 1871-2099 in 38 cells in the Caribbean region   总被引：1，自引：0，他引：1  

Sheppard C  Rioja-Nieto R 《Marine environmental research》2005,60(3):389-396

Sea surface temperature (SST) data with monthly resolution are provided for 38 cells in the Caribbean Sea and Bahamas region, plus Bermuda. These series are derived from the HadISST1 data set for historical time (1871-1999) and from the HadCM3 coupled climate model for predicted SST (1950-2099). Statistical scaling of the forecast data sets are performed to produce confluent SST series according to a now established method. These SST series are available for download. High water temperatures in 1998 killed enormous amounts of corals in tropical seas, though in the Caribbean region the effects at that time appeared less marked than in the Indo-Pacific. However, SSTs are rising in accordance with world-wide trends and it has been predicted that temperature will become increasingly important in this region in the near future. Patterns of SST rise within the Caribbean region are shown, and the importance of sub-regional patterns within this biologically highly interconnected area are noted.  相似文献   

A note on nearshore wave features: Implications for wave generation     

Rodolfo Bolaos  Agustín Snchez-Arcilla 《Progress in Oceanography》2006,70(2-4):168

This paper analyses 10 years of wave data from the Mediterranean Spanish (Catalan) coast considering the mean wave climate and storm events from the standpoint of wind-wave momentum transfer and wave prediction. The data, registered by a buoy at about 12 km from the coastline, revealed two main groups of wave storms, with NW and E directions. NW storms correspond to a fetch-limited situation since the intense wind blows from land. Low-pressure centres located over the Mediterranean Sea produce easterly storms. Near the coast the eastern winds from the sea are replaced by NW winds coming from meteorological patterns over northern Spain and south-western France. Wave storms are classified and studied to obtain their main features (including spectral width, wave length, wave age and bimodality) and discussed in terms of wind-wave momentum transfer for operational wave predictions. Observations show a complex coastal wave climate. Fetch-limited storms presented smaller spectral widths while varying wind situations presented larger widths due to the presence of bimodal spectra. These wave features are highly relevant for wind–ocean momentum transfer and, thus, for current and wave predictions. The spectral width proved to be a good indicator of sea complexity and is thus applicable for improved wind drag estimations. A new drag coefficient formulation is proposed, based on existing wind dependent drag expressions, but including also spectral wave properties (a spectral width parameter) that highlights the characteristics of wind-wave generation under pre-existing swell. Such a formulation, once properly validated with field observations, is expected to improve wind-wave predictions.  相似文献   

Verification of a One-Dimensional Model of $$\hbox {CO}_{2}$$ Atmospheric Transport Inside and Above a Forest Canopy Using Observations at the Norunda Research Station     

Ivan Kovalets  Rodolfo Avila  Meelis Mölder  Sophia Kovalets  Anders Lindroth 《Boundary-Layer Meteorology》2018,168(1):103-126

A model of \(\hbox {CO}_{2}\) atmospheric transport in vegetated canopies is tested against measurements of the flow, as well as \(\hbox {CO}_{2}\) concentrations at the Norunda research station located inside a mixed pine–spruce forest. We present the results of simulations of wind-speed profiles and \(\hbox {CO}_{2}\) concentrations inside and above the forest canopy with a one-dimensional model of profiles of the turbulent diffusion coefficient above the canopy accounting for the influence of the roughness sub-layer on turbulent mixing according to Harman and Finnigan (Boundary-Layer Meteorol 129:323–351, 2008; hereafter HF08). Different modelling approaches are used to define the turbulent exchange coefficients for momentum and concentration inside the canopy: (1) the modified HF08 theory—numerical solution of the momentum and concentration equations with a non-constant distribution of leaf area per unit volume; (2) empirical parametrization of the turbulent diffusion coefficient using empirical data concerning the vertical profiles of the Lagrangian time scale and root-mean-square deviation of the vertical velocity component. For neutral, daytime conditions, the second-order turbulence model is also used. The flexibility of the empirical model enables the best fit of the simulated \(\hbox {CO}_{2}\) concentrations inside the canopy to the observations, with the results of simulations for daytime conditions inside the canopy layer only successful provided the respiration fluxes are properly considered. The application of the developed model for radiocarbon atmospheric transport released in the form of \(^{14}\hbox {CO}_{2}\) is presented and discussed.  相似文献   

Enrichment of redox-sensitive trace metals (U,V, Mo,As) associated with the late Hauterivian Faraoni oceanic anoxic event     

Stéphane Bodin  Alexis Godet  Virginie Matera  Philipp Steinmann  Jean Vermeulen  Silvia Gardin  Thierry Adatte  Rodolfo Coccioni  Karl B. Föllmi 《International Journal of Earth Sciences》2007,96(2):327-341

The Faraoni Level is a short-lived oxygen-deficient event that took place during the latest Hauterivian. In order to improve our understanding of the palaeoenvironmental conditions that occurred during this event, we have analysed the contents of several redox-sensitive trace elements (U, V, Mo, As, Co, Cd, Cu, Zn, Ni, Pb, Cr) from bulk limestone samples of late Hauterivian–early Barremian age from three reference sections. U, V, Mo and As show consistent and significant enrichments during the Faraoni event whereas the other redox-sensitive trace elements analysed here are not systematically enriched. In order to explain this discrepant behaviour, we propose that the Faraoni Level was deposited during a period of anoxic conditions near the sediment–water interface. The distinctive peaks in U, V, Mo and As contents are traceable throughout the three studied sections and represent a good correlation tool which helps to identify the Faraoni Level and its equivalents in the western Tethyan realm and outside of the Tethys. For example, a peak in U contents in upper Hauterivian sediments of the northwestern Pacific realm (ODP leg 185, site 1149) may well be an expression of the Faraoni event in this particular basin.  相似文献