Interpretation of temporal features in an unusual X-ray and microwave burst     

A. L. Mackinnon  J. E. R. Costa  P. Kaufmann  B. R. Dennis 《Solar physics》1986,104(1):191-198

Observations are briefly discussed of an event in which microwave and hard X-ray emissions were not correlated in the accepted way. Two impulsive peaks of roughly equal intensity were observed at three different microwave frequencies. The hard X-ray peaks accompanying these, however, differ in intensity by almost two orders of magnitude. Various possible interpretations of this burst are discussed, in the context of familiar models of these emissions. The most likely explanation is that the electron spectrum in the first burst has a break at about 350 keV. General implications for interpretation of X-rays and microwaves are discussed.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985.  相似文献   

Conservation Priority Index for Estuarine Fish (COPIEF)     

Paulo Branco  Jos Lino Costa  Pedro Raposo de Almeida 《Estuarine, Coastal and Shelf Science》2008,80(4):581-588

Public awareness regarding environmental issues has increased in recent decades. The increasing number of impact assessment studies, management and conservation plans, as well as ecological monitoring studies, demand new and more efficient techniques. Indices are an important tool to aid biologists in these studies and should allow an easier comprehension of the data by managers, decision-makers and the general public. This study presents the first multi-metrical index able to establish a hierarchical ordination of the conservation priority of the estuarine fish species using 72 species from 16 estuarine systems (W and S coasts of Portugal). The index is composed of 10 metrics, comprising species life traits, distribution and population trends. The information needed to score each metric was gathered from the published literature and the index validation was done by external means. This methodology allowed the definition of those fish species most in need of conservation planning, and those less prone to extinction in Portuguese estuarine systems. The proposed index fills a gap in our knowledge and provides a useful tool to the scientific community and to the decision-makers, being a breakthrough in the field of conservation planning of estuarine fish species.  相似文献   

The ignored but common nemertine Psammamphiporus elongatus from the Galician beaches (Spain), affected by the Prestige oil spill     

Alfonso Herrera-Bachiller  Pedro García-Corrales  Carmen Roldán  & Juan Junoy 《Marine Ecology》2008,29(S1):43-50

Nemerteans have been recorded in several studies of the sandy beaches, but usually these specimens have been only regarded as members of the Phylum, with no attempt at identification at any taxonomic level. This lack of identification is partly because of the sampling procedures used to collect beach macroinfauna. Nemerteans are fragile and need special care. They must be isolated and observed in vivo before using histological procedures, which must be employed for the taxonomical studies. This study deals with a sandy beach hoplonemertean, Psammamphiporus elongatus ( Stephenson 1911 ), only known for seven specimens from the Firth of Clyde (UK). This species is recorded for the first time from the Galician sandy beaches (NW Spain) where it reaches its maximum abundance. The species is described and illustrated and new data on its morphology and ecology are provided. The species was apparently affected by the 'Prestige' oil spill, and would be a good indicator of beach quality.  相似文献   

The trade of live crustaceans in Portugal: space for technological improvements     

Barrento  Sara; Marques  Antonio; Pedro  Sonia; Vaz-Pires  Paulo; Nunes  Maria Leonor 《ICES Journal of Marine Science》2008,65(4):551-559

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Dynamics of arrays of floating point-absorber wave energy converters with inter-body and bottom slack-mooring connections     

Pedro C. Vicente  António F. de O. Falcão  Luís M.C. Gato  Paulo A.P. Justino 《Applied Ocean Research》2009,31(4):267-281

If point absorbers are employed in the extensive exploitation of the offshore wave energy resource, they should be deployed in arrays, the distance between the elements in the array being possibly tens of meters. In such cases, it may be more convenient that the array is spread moored to the sea bottom through only some of its elements, located in the periphery, while the other array elements are prevented from drifting and colliding with each other by connections to adjacent elements. An array of identical floating point absorbers located at the grid points of an equilateral triangular grid is considered in the paper. A spread set of slack-mooring lines connect the peripheric floaters to the bottom. A weight is located at the centre of each triangle whose function is to pull the three floaters towards each other and keep the inter-body mooring lines under tension. The power take-off system (PTO) is a linear damper activated by the buoy heaving motion. The whole system–buoys, moorings and power take-off systems–is assumed linear, so that a frequency domain analysis may be employed. Hydrodynamic interference between the oscillating buoys in array is accounted for. Equations are presented for a set of three identical point absorbers. This is then extended to more complex equilateral triangular grid arrays. Results from numerical simulations, with regular and irregular waves, are presented for the motions and power absorption of hemispherical converters in arrays of three and seven elements and for different mooring parameters and wave incidence angles. Comparisons are given with the unmoored and independently-moored buoy situations.  相似文献   

Small-scale distribution of Solea solea and Solea senegalensis juveniles in the Tagus estuary (Portugal)     

C. Vinagre  A. Maia  P. Reis-Santos  M.J. Costa  H.N. Cabral 《Estuarine, Coastal and Shelf Science》2009,81(3):296-300

The distribution of Solea solea and Solea senegalensis in the Tagus estuary was studied following a small-scale approach. Preliminary sampling revealed that sole concentrated in two areas within their nursery grounds, the main subtidal channel and a large intertidal mudflat. Beam trawls were conducted intensively in the two areas in July 2006. Depth, salinity and water temperature were measured. Substrate samples were collected for sediment type determination and macrobenthos identification and quantification. Generalized linear models were applied in order to explain the occurrence and variability of soles' densities, using depth, salinity, water temperature and abundance of polychaetes, oligochaetes, amphipods, isopods and bivalves as explanatory variables. While S. solea was more abundant in the main subtidal channel, a deeper, warmer and lower salinity area, S. senegalensis abundance was highest at the intertidal mudflat area. Presence of both species in the two areas was associated with abundance of polychaetes (generally with another variable associated), and for S. senegalensis in the subtidal channel it was associated with amphipods and depth. Abundance of S. solea in the main subtidal channel was associated mainly with polychaetes abundance, while that of S. senegalensis was associated with amphipods density. In the intertidal mudflat, bivalves and polychaetes presented significant relationships with both species densities. Some of the factors that had been reported to be important for the distribution of these species in previous studies also do so at a finer scale; however, this small-scale approach provided an in-depth knowledge on habitat selection and spatial segregation of these species within this nursery area.  相似文献   

Concurrent imaging of chlorophyll fluorescence,Chlorophyll a content and green fluorescent proteins‐like proteins of symbiotic cnidarians          下载免费PDF全文

Miguel Costa Leal  Bruno Jesus  João Ezequiel  Ricardo Calado  Rui Jorge Miranda Rocha  Paulo Cartaxana  João Serôdio 《Marine Ecology》2015,36(3):572-584

Research on photosynthetic cnidarians has been mainly focused on the symbiosis established between the cnidarian host and its dinoflagellates endosymbionts from genus Symbiodinium. Despite the potential of imaging techniques for assessing the spatial distribution of key parameters of cnidarian photobiology, such as photochemical activity, chlorophyll a content or green fluorescent proteins (GFPs), to our best knowledge, no study has ever attempted to simultaneous map these three features. In this study, we developed a modified imaging pulse amplitude fluorometer by applying excitation light of different wavelengths and selectively detecting short spectral bands through bandpass filters. The imaging system was used to sequentially excite and quantify chlorophyll variable fluorescence (maximum quantum yield of photosystem II, F_v/F_m), Chl a content (normalized difference vegetation index) and relative content of GFPs. The spatial distribution of these photophysiological parameters was mapped both horizontally, across the surface of the soft corals Sarcophyton cf. glaucum and Sinularia flexibilis and the zoanthid Protopalythoa sp., and vertically, throughout a vertical section of S. cf. glaucum. Results showed bleached areas within each individual coral colony and registered photophysiological changes with S. cf. glaucum tissue depth. Analysis of Protopalythoa sp. polyps’ expansion revealed differential surface patterns of NDVI and GFP concentration, and a negative relation between these latter parameters within each polyp. This novel non‐invasive approach allowed a high‐resolution characterization of the spatial relationship between these key parameters through the analysis of image information on a pixel‐by‐pixel basis, which has great potential for investigating the physiological state of symbiotic associations.  相似文献   

Oscillations in the Flaring Active Region NOAA 11272     

S. M. Conde Cuellar  J. E. R. Costa  C. E. Cedeño Montaña 《Solar physics》2016,291(11):3289-3302

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On using a generalized linear model to downscale daily precipitation for the center of Portugal: an analysis of trends and extremes     

Mário Pulquério  Pedro Garrett  Filipe Duarte Santos  Maria João Cruz 《Theoretical and Applied Climatology》2015,120(1-2):147-158

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POLARIX: a pathfinder mission of X-ray polarimetry     

Enrico Costa  Ronaldo Bellazzini  Gianpiero Tagliaferri  Giorgio Matt  Andrea Argan  Primo Attinà  Luca Baldini  Stefano Basso  Alessandro Brez  Oberto Citterio  Sergio Di Cosimo  Vincenzo Cotroneo  Sergio Fabiani  Marco Feroci  Antonella Ferri  Luca Latronico  Francesco Lazzarotto  Massimo Minuti  Ennio Morelli  Fabio Muleri  Lucio Nicolini  Giovanni Pareschi  Giuseppe Di Persio  Michele Pinchera  Massimiliano Razzano  Luigia Reboa  Alda Rubini  Antonio Maria Salonico  Carmelo Sgro’  Paolo Soffitta  Gloria Spandre  Daniele Spiga  Alessio Trois 《Experimental Astronomy》2010,28(2-3):137-183

Since the birth of X-ray astronomy, spectral, spatial and timing observation improved dramatically, procuring a wealth of information on the majority of the classes of the celestial sources. Polarimetry, instead, remained basically unprobed. X-ray polarimetry promises to provide additional information procuring two new observable quantities, the degree and the angle of polarization. Polarization from celestial X-ray sources may derive from emission mechanisms themselves such as cyclotron, synchrotron and non-thermal bremsstrahlung, from scattering in aspheric accreting plasmas, such as disks, blobs and columns and from the presence of extreme magnetic field by means of vacuum polarization and birefringence. Matter in strong gravity fields and Quantum Gravity effects can be studied by X-ray polarimetry, too. POLARIX is a mission dedicated to X-ray polarimetry. It exploits the polarimetric response of a Gas Pixel Detector, combined with position sensitivity, that, at the focus of a telescope, results in a huge increase of sensitivity. The heart of the detector is an Application-Specific Integrated Circuit (ASIC) chip with 105,600 pixels each one containing a full complete electronic chain to image the track produced by the photoelectron. Three Gas Pixel Detectors are coupled with three X-ray optics which are the heritage of JET-X mission. A filter wheel hosting calibration sources unpolarized and polarized is dedicated to each detector for periodic on-ground and in-flight calibration. POLARIX will measure time resolved X-ray polarization with an angular resolution of about 20 arcsec in a field of view of 15 × 15 arcmin and with an energy resolution of 20% at 6 keV. The Minimum Detectable Polarization is 12% for a source having a flux of 1 mCrab and 10⁵ s of observing time. The satellite will be placed in an equatorial orbit of 505 km of altitude by a Vega launcher. The telemetry down-link station will be Malindi. The pointing of POLARIX satellite will be gyroless and it will perform a double pointing during the earth occultation of one source, so maximizing the scientific return. POLARIX data are for 75% open to the community while 25% + SVP (Science Verification Phase, 1 month of operation) is dedicated to a core program activity open to the contribution of associated scientists. The planned duration of the mission is one year plus three months of commissioning and SVP, suitable to perform most of the basic science within the reach of this instrument. A nice to have idea is to use the same existing mandrels to build two additional telescopes of iridium with carbon coating plus two more detectors. The effective area in this case would be almost doubled.  相似文献