Area usage estimation and spatiotemporal variability in distribution patterns of southern right whales,Eubalaena australis,of southern Brazil          下载免费PDF全文

Eduardo Pires Renault‐Braga  Karina Rejane Groch  Paulo A. de Carvalho Flores  Eduardo R. Secchi  Luciano Dalla‐Rosa 《Marine Ecology》2018,39(3)

Southern right whales—Eubalaena australis (Desmoulins, 1822)—migrate seasonally from high‐latitude feeding grounds to coastal breeding and calving grounds at lower latitudes such as the southern coast of Brazil. Understanding how these whales are distributed along the coast is important for monitoring their postwhaling recovery and defining management strategies. In this study, we applied Kernel density estimators to aerial survey data to determine main occurrence and concentration areas of right whales in southern Brazil and investigate inter‐ and intra‐annual distribution patterns between 2003 and 2012. Our results show considerable variation in area usage within and among years, and changes in the general distribution pattern of right whales in the last years of the study. Intra‐annually, higher concentration area tended to expand from July to September and decrease in November. Some areas stood out as high‐density areas for right whales: Ribanceira/Ibiraquera, Itapirubá Sul/Sol, and from Arroio to Gaivota. Some evidences also suggest preferential areas for mother–calf pairs. The higher concentration area of right whales in southern Brazil was estimated at 52,541 km² and the occurrence area was 682.69 km², which is the whole study area. As right whale distribution in the region is likely expanding due to this population's current recovery, our study provides essential information for management plan of the Right Whale Environmental Protection Area.  相似文献   

Is primordial ⁴He truly from the Big Bang?     

R. Salvaterra  A. Ferrara 《Monthly notices of the Royal Astronomical Society》2003,340(3):L17-L20

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Detecting the first objects in the mid-infrared with the Next Generation Space Telescope     

Benedetta Ciardi †  rea Ferrara 《Monthly notices of the Royal Astronomical Society》2001,324(3):648-652

We calculate the expected mid-infrared (MIR) molecular hydrogen line emission from the first objects in the Universe. As a result of their low masses, the stellar feedback from massive stars is able to blow away their gas content and collect it into a cooling shell where H₂ rapidly forms and IR roto-vibrational (as for example the rest-frame 2.12 μm) lines carry away a large fraction (up to 10 per cent) of the explosion energy. The fluxes from these sources are in the range 10⁻²¹–10⁻¹⁷ erg s⁻¹ cm⁻² . The highest number counts are expected in the 20-μm band, where about 10⁵ sources deg⁻² are predicted at the limiting flux of 3×10⁻¹⁸ erg s⁻¹ cm⁻². Among the planned observational facilities, we find that the best detection perspectives are offered by the Next Generation Space Telescope ( NGST ), which should be able to reveal about 200 first objects in one hour observation time at its limiting flux in the above band. Therefore, mid-IR instruments appear to represent perfect tools to trace star formation and stellar feedback in the high ( z ≳5) redshift Universe.  相似文献   

Molecular hydrogen in damped Lyα systems: spatial distribution     

H. Hirashita  †  A. Ferrara  K. Wada  P. Richter 《Monthly notices of the Royal Astronomical Society》2003,341(3):L18-L22

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Remote estimation of surficial seafloor properties through the application Angular Range Analysis to multibeam sonar data   总被引：2，自引：2，他引：2  

Luciano Fonseca  Larry Mayer 《Marine Geophysical Researches》2007,28(2):119-126

The variation of the backscatter strength with the angle of incidence is an intrinsic property of the seafloor, which can be used in methods for acoustic seafloor characterization. Although multibeam sonars acquire backscatter over a wide range of incidence angles, the angular information is normally neglected during standard backscatter processing and mosaicking. An approach called Angular Range Analysis has been developed to preserve the backscatter angular information, and use it for remote estimation of seafloor properties. Angular Range Analysis starts with the beam-by-beam time-series of acoustic backscatter provided by the multibeam sonar and then corrects the backscatter for seafloor slope, beam pattern, time varying and angle varying gains, and area of insonification. Subsequently a series of parameters are calculated from the stacking of consecutive time series over a spatial scale that approximates half of the swath width. Based on these calculated parameters and the inversion of an acoustic backscatter model, we estimate the acoustic impedance and the roughness of the insonified area on the seafloor. In the process of this inversion, the behavior of the model parameters is constrained by established inter-property relationships. The approach has been tested using a 300 kHz Simrad EM3000 multibeam sonar in Little Bay, NH. Impedance estimates are compared to in situ measurements of sound speed. The comparison shows a very good correlation, indicating the potential of this approach for robust seafloor characterization.  相似文献   

A wave model for the Great Barrier Reef   总被引：1，自引：0，他引：1  

Thomas A. Hardy  Luciano B. Mason  Jason D. McConochie 《Ocean Engineering》2001,28(1):1869

A new wind wave generation model, WAMGBR, is presented that has been adapted from WAM especially for use in the complex geometry of the Great Barrier Reef. A technique (reef parameterization) has been presented that incorporates sub-grid scale dissipation caused by coral reefs. Three other improvements to WAM have been proposed. An explicit/implicit finite difference scheme has been implemented that allows for more efficient modelling (longer time steps) while maintaining diffusive characteristics that are at least as good as those of WAM. An offset in discrete angles creates more uniform diffusive characteristics. And, a transformed spherical coordinate system allows for more efficient grid sizes and smaller grid dependent refraction. Comparisons between modelling techniques and between model and measured data show that WAMGBR produces very good results in the difficult challenge of modelling both non-cyclonic and tropical cyclone waves in the geographically complex environment of the Great Barrier Reef.  相似文献   

Rb/Sr dating of the Upper Proterozoic basement of Zambesia,Mozambique     

Mario Costa  Giorgio Ferrara  Rosalino Sacchi  Sonia Tonarini 《International Journal of Earth Sciences》1992,81(2):487-500

The Proterozoic basement of the Province of Zambezia (Mozambique) is located near the southern end of the so called Mozambique Belt. Rb-Sr data derived from the analyses of 66 whole rocks and a few mineral samples bear witness of a magmatic and metamorphic episode referable to the Kibaran (ca. 1000 Ma) and helped to model the late-Proterozoic evolution as follows. At 1100–1050 Ma a pre-orogenic, calc-alkaline magmatism was responsible for the emplacement of now deformed granite and granodiorite. This phase was accompanied by rhyolitic volcanism. A subsequent peak of deformation and metamorphism occurred at 1000-950 Ma and was associated with a second generation of substantially post-tectonic granites. A thermal event resulting in the emplacement of a final generation of granites and pegmatites can be dated to around 500-450 Ma.The metamorphic basement has not preserved its protolith age, probably as a result of extensive isotopic homogeneization of Sr in Kibaran times. Its maximum time of differentiation from the mantle should be around 1600 Ma.The very low values of initial Sr isotopic ratios suggest the absence of Archean crustal precursors and support the rather young, yet pre-Pan-African evolution of the southernmost Mozambique Belt.

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Zusammenfassung Das proterozoische Grundgebirge der Provinz Zambesi (Mosambique) befindet sich in der Nähe des südlichen Endes des sogenannten Mozambique Belt. Rb/Sr Daten aus 66 Ganzgesteins- und einigen Mineralanalysen zeugen von einer magmatischen und metamorphen Episode die sich dem Kibaran (ca. 1000 Ma) zuordnen läßt, und wie sich im folgenden zeigt, hilfreich bei der Modellisierung der spätproterozoischen Entwicklung ist. Um 1100 bis 1050 Ma erfolgte ein präorogener kalkalkalischer Magmatismus, bestehend aus Graniten und Granodioriten, die heute deformiert vorliegen. Diese Phase wurde von rhyolithischem Vulkanismus begleitet. Von 1000 bis 950 Ma folgte der Höhepunkt der Deformation und Metamorphose, begleitet von einer bedeutenden 2. Generation posttektonischer Granite. Bedingt durch ein weiteres thermales Ereignis intrudierte die letzte Granit- und Pegmatitgeneration vor 500 bis 450 Ma.Im metamorphen Grundgebirge ist das Eduktalter vermutlich aufgrund der starken isotopischen Homogenisierung von Sr während der Kibara-Zeit nicht erhalten. Seine maximale Differentiationszeit vom Mantel muß vor 1600 Ma gewesen sein.Die sehr niedrigen Gehalte der initialen Sr-Isotopenverhältnisse lassen die Abwesenheit von archaischen Krustenvorläufern vermuten, und unterstützen die sehr junge, bis jetzt Prä-Pan-Afrikanische Entwicklung des südlichsten Mozambique Belts.

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Résumé Le socle protérozoïque de la province du Zambèze, au Mozambique, se trouve à proximité de l'extrémité sud du «Mozambique Belt». Des mesures Rb/Sr effectuées sur 66 roches totales et sur quelques minéraux témoignent d'un épisode magmatique et métamorphique attribuable au Kibarien (environ 1.000 Ma), ce qui permet de se représenter comme suit l'histoire de cette région au Protérozoïque supérieur. Il y a 1.100 à 1.050 Ma, la région a connu une phase de magmatisme calco-alcalin qui s'est traduite par la mise en place de granites et granodiorites, aujord'hui déformés. Cette phase s'est accompagnée d'un volcanisme rhyolitique. Elle a été suivie, entre 1.000 et 950 Ma, d'une activité tectono-métamorphique majeure, à laquelle est associée une deuxième et importante génération de granites, post-tectoniques. Ultérieurement, la région a connu encore un épisode thermique, daté à 500-450 Ma, responsable de la mise en place d'une dernière génération de granite et de pegmatite.Le socle métamorphique n'a pas gardé de témoins de l'âge de son protolithe, en raison probablement de la forte homogénisation isotopique du Sr à l'époque kibarienne. Lâge maximal de sa différenciation à partir du manteau doit se situer autour de 1.600 Ma.La valeur très basse des rapports isotopiques initiaux du Sr suggère l'absence de précurseurs crustaux archéens et incite à admettre une évolution relativement jeune — bien que pré-panafricaine — du «Mozambique Belt» méridional.

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Shear wave splitting changes associated with the 2001 volcanic eruption on Mt Etna     

Francesca Bianco  Luciano Scarf&#;  Edoardo Del Pezzo  Domenico Patanè 《Geophysical Journal International》2006,167(2):959-967

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Melt/biotite B/B isotopic fractionation and the boron local environment in the structure of volcanic glasses     

Sonia Tonarini  Claudia Forte  Giorgio Ferrara 《Geochimica et cosmochimica acta》2003,67(10):1863-1873

This paper is focused on the role of boron coordination in determining the ¹¹B/¹⁰B isotopic fractionation between melt/glass and biotite at magmatic temperatures. For this purpose, three evolved volcanic rocks from Roccastrada, Mt. Amiata, and Mt. Cimini belonging to the Neogene-Quaternary magmatism of central Italy were studied. In these samples, the measured boron biotite-glass partition coefficient ranges between 0.004 and 0.011, indicating that boron behaves as an incompatible element during biotite crystallization. The ¹¹B magic-angle spinning nuclear magnetic resonance (NMR) spectra reveal the presence of trigonal BO_3/2 units, tetrahedral BO_4/2⁻ sites, and three-coordinated BO_2/2O⁻ species containing one nonbridging oxygen. The relative contributions of these different boron sites were estimated by spectral deconvolution, and it was observed that the fraction of trigonally coordinated boron decreases with increasing K₂O concentration in the glass. The ¹¹B/¹⁰B isotopic fractionation between biotite and melt/glass was observed to be large even at magmatic temperatures and was found to be 1.0066 (Roccastrada sample), 1.00535 (Mt. Amiata sample), and 1.00279 (Mt. Cimini sample). Fractionation is mostly related to the relative amount of trigonal and tetrahedral boron sites in the glass network rather than to other processes, including the speciation of hydrous species in the glass structure. The measured α values are significantly higher than the calculated ones obtained using the reduced partition function ratios (RPFRs) for B(OH)₃ and B(OH)₄⁻ as reported by Kakihana et al. (1977) and the abundance of trigonal and tetrahedral boron obtained by ¹¹B NMR spectra. Furthermore, a nonlinear relationship is observed between the percentage of BO₄ in the glass structure and the measured 1000lnα, suggesting that the approximation of monomeric B(OH)₃ and B(OH)₄⁻ species contributions through ideal mixing in calculating the RPFRs in polyanions (Oi et al., 1989) probably does not apply to silicate glasses.The large B isotopic fractionation measured between glass and biotite and its dependence on the boron coordination in the glass are a limitation to the use of δ¹¹B in the mineral to characterize magmas. Nonetheless, the high incompatible behavior of boron in the most common magmatic minerals rules out that fractional crystallization significantly modified the B isotopic composition of the melt.  相似文献   

Landslide hazard in the Nebrodi Mountains (Northeastern Sicily)   总被引：1，自引：1，他引：1  

A. Cubito  V. Ferrara  G. Pappalardo 《Geomorphology》2005,66(1-4):359

The eastern sector of the Nebrodi Mountains (NE Sicily), a part of the Apenninic-Maghrebian orogenic chain, is characterized by an high landslide hazard. The village of S. Domenica Vittoria, which lies in the area, has been particularly affected by various landslide phenomena, with resulting damage to buildings and infrastructure.The rocks outcropping in the area belong to the Cretaceous Monte Soro Flysch; they consist of an alternation of argillaceous and calcareous beds at the base and argillaceous and quartzarenitic beds at the top. The lithotechnical characteristics of the formation and the steepness of the slopes in the area lead to an elevated instability, as testified by the widespread occurrence of sub-vertical arcuate cliffs (landslide scarps) and sub-horizontal areas (landslide terraces), typical of a landslide-controlled morphology. From a kinematics point of view, the observed phenomena can be referred to multiple rotational slides, flows, and complex landslides, often with a retrogressive development and enlargement. Triggering causes lie principally in the intense rainfalls that determine the decay of the geomechanical properties of the terrain and supply discontinuos groundwater circulation that is evident in seasonal springs. Human activity, such as the construction of roads and buildings on steep slopes and dispersal of water from supply systems and sewers has a significant impact as well.Due to the instability of the area, expansion of the village, which is already limited by the morphological conditions, is made difficult by the high hazard level, especially in the areas at higher elevations, where the principal landslide scarps are located, and even more on the rims of the scarps. Considering the high hazard level, S. Domenica Vittoria has been inserted by the National Geological Service among the sites in Sicily to be monitored by means of a GPS network. The survey carried out along the entire slope hosting the village has furnished the base for geological and geomorphological knowledge needed for the planning of the network, to identify the areas at landslide risk, where parts of the village lie, including the areas of expansion of the village, the main roads, and a portion of the Favoscuro river bed.  相似文献