A search for S stars in the IRC and AFGL Catalogues     

A. Borghesi  E. Bussoletti  L. Rossi  S. Uras 《Astrophysics and Space Science》1981,78(2):435-441

There is a clear relation between the amplitude of the visual light curve, the period and the luminosity of the low amplitude Scuti stars.  相似文献   

Effects of some representative petroleum refinery effluent compounds on photosynthesis and growth of natural marine phytoplankton assemblages: Part 1—cresols     

W.H Thomas  S.S Rossi  D.L.R Seibert 《Marine environmental research》1981,4(3):203-215

The effects of cresols on the photosynthesis and growth of natural marine phytoplankton assemblages from the Scripps Pier at La Jolla, California, USA were measured. In two experiments, in which dinoflagellates were the dominant algae, photosynthesis (measured by ¹⁴C uptake) was inhibited at concentrations > 100 μg litre^?1 and the concentration giving half-maximal photosynthesis was 10,000 μg litre^?1. In a third experiment, in which diatoms were dominant, photosynthesis was not inhibited until levels > 10,000 μg litre^?1 were reached and the half-maximal concentration was 20,000 μg litre^?1. These experiments suggested that dinoflagellates were more sensitive to cresols than diatoms. However, the reverse was true in an experiment using cultures. In a long-term growth experiment (natural assemblages from the Scripps Pier), only a level of 88,000 μg litre^?1 completely inhibited growth. There was a two-day lag in growth at 8500 μg litre^?1, but the algae recovered and grew as well as the controls which contained no cresols. This experiment was started with a mixed diatom-dinoflagellate-microflagellate population but only the diatoms grew. High concentrations of cresols (> 900 μg litre^?1) resulted in a decrease in the diatom Skeletonema costatum, compared with the controls. Otherwise there was no selection for resistant species. In these experiments, cresols were measured by extraction with methylene chloride from seawater followed by measurement by UV absorption. In all experiments cresol levels decreased with time. This was attributed to uptake by phytoplankton and bacterial degradation.  相似文献   

The infaunal community in experimentally seeded low and high density Manila clam (Tapes philippinarum) beds in a Po River Delta lagoon (Italy)     

Mantovani  S.; Castaldelli  G.; Rossi  R.; Fano  E.A. 《ICES Journal of Marine Science》2006,63(5):860-866

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Disturbance and Community Pattern of Polychaetes Inhabiting Valle Magnavacca (Valli di Comacchio,Northern Adriatic Sea,Italy)     

Michele Mistri  Elisa A. Fano  Francesco Ghion  Remigio Rossi 《Marine Ecology》2002,23(1):31-49

Abstract. Polychaete community structure in Valle Magnavacca, the largest basin of the Valli di Comacchio (Northern Adriatic Sea) lagoonal ecosystem, was analyzed in a three‐year study. Three shallow‐water stations were sampled at about 3‐month intervals. Univariate and multivariate analyses were utilized to investigate community structure changes in relation to natural and man‐induced disturbance. The polychaete community at station 3, in the central area of the lagoon, was the most disturbed, while that of station 2 was the most well structured. We hypothesize that polychaete community structure results from regular seasonal disturbances which lead to almost predictable fluctuations in species abundance. Superimposed on these regular cycles are acute disturbance events that further reduce species abundance or exclude species from the habitat.  相似文献   

Cadmium toxicity in spiked sediment to sea urchin embryos and sperm     

G. Pagano  M. Iaccarino  M. Guida  S. Manzo  G. Melluso  R. Oral  R. Romanell  M. Rossi 《Marine environmental research》1996,42(1-4)

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Natural frequencies of a vibrating repaired panel in an ocean structure     

D.H. FelixD.V. Bambill  C.A. RossitR.E. Rossi  P.A.A. Laura 《Ocean Engineering》2003,30(8):955-963

The present work arose from the need of repairing steel plates badly damaged by corrosion in a portion of the structural element of the naval vehicle. The possibility of removing the portion and replacing it by a patch of a composite material was considered. Its dynamic behavior is altered by the introduction of the patch and the prediction of its new behavior is of great interest in many situations. This condition would appear in other real-life situations like as a localized orthotropic effect caused in the panel by a welding procedure or a metallurgical process. The first four natural frequency coefficients of the composite repaired panel with different types of boundary conditions are determined by means of a variational approach. The displacement function is approximated making use of complete sets of beam functions. The eigenvalues have been computed from (225×225) secular determinants. An independent solution is obtained using the finite element method and a reasonably good agreement with the analytical solution is encountered.  相似文献   

Cartography of the <Emphasis Type="Italic">b</Emphasis>-plane of a close encounter I: semimajor axes of post-encounter orbits     

G. B. Valsecchi  E. M. Alessi  A. Rossi 《Celestial Mechanics and Dynamical Astronomy》2018,130(2):8

Close planetary encounters play an important role in the evolution of the orbits of small Solar system bodies and are usually studied with the help of numerical integrations. Here we study close encounters in the framework of an analytic theory, focusing on the so-called b-plane, which is the plane centred on the planet and perpendicular to the planetocentric velocity at infinity of the small body. As shown in previous papers, it is possible to identify the initial conditions on the b-plane that lead to post-encounter orbits of given semimajor axis. In this paper we exploit analytical relationships between b-plane coordinates and pre-encounter orbital elements and compute the probability of transition to these post-encounter states, and numerically check the validity of the analytic approach.  相似文献   

CCD cameras and Spacewire interfaces for HERSCHEL/SCORE suborbital mission     

A. Gherardi  M. Romoli  E. Pace  M. Pancrazzi  G. Rossi  D. Paganini  M. Focardi 《Astrophysics and Space Science》2009,320(1-3):239-241

The HERSCHEL/SCORE is a suborbital mission which will observe the solar corona in UV and in visible light for measurements of solar corona. The coronagraph for such observation is an Italian instrument and, in particular, the CCD camera detectors are developed at the XUVLab of the Department of Astronomy and Space Science of Florence University. Such detectors communicate with the onboard computer by means the IEEE1355 Spacewire standard interface (developed in our laboratories) and implement a lot of smart and custom procedures for imaging. The main innovation of SCORE coronagraph is the first use in space of a variable retarder plate based on liquid crystals and the optical design capable of simultaneous observation in UV and Visible light.  相似文献   

Innovative methods of correlation and orbit determination for space debris     

Davide Farnocchia  Giacomo Tommei  Andrea Milani  Alessandro Rossi 《Celestial Mechanics and Dynamical Astronomy》2010,107(1-2):169-185

We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for a given observation for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the J ₂ effect.  相似文献   

New data for the kinematic interpretation of the Alps–Apennines junction (Northwestern Italy)     

Pietro Mosca  Riccardo Polino  Sergio Rogledi  Massimo Rossi 《International Journal of Earth Sciences》2010,99(4):833-849

Alps and Apennines are juxtaposed within an approximately 100 km-wide area covered by the Upper Eocene to Miocene successions of the Tertiary Piedmont Basin. The Upper Eocene–Oligocene evolution of this area was characterized to the north and west by the propagation of the SE-verging Southalpine thrust-fold belt that can be traced from the Po Plain subsurface until the Torino Hill-Saluzzese area, and to the south by a high-angle, broadly E–W oriented megashear zone that led to the juxtaposition of different crustal levels and controlled the development of a mosaic of partly independent sub-basins. Since the latest Oligocene the N-verging Apenninic tectonics prevailed in the collisional system and the Tertiary Piedmont Basin evolved as a wide thrust-top basin, bounded to the north by the N-verging Monferrato arc and characterized by a tectono-sedimentary evolution recording changes of subsidence and shift of depocentres in relation to crustal structures.  相似文献