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21.
Harmful algal blooms (HABs), more specifically red tides, are among the most critical environmental factors affecting mussel cultivation in Galicia (NW Spain), and they often have been blamed for economic losses for producers. This statement is based on the correlation between days of closure of the production areas and unsold product. The present article shows that such a statement is not always correct, at least in the case of Galician mussel farming, because red tides only cause losses to producers under specific circumstances that arise from the impossibility of placing their product in the market. In addition, this article reveals the importance of finding organizational solutions within the framework of the production sector to counteract the impact of this type of phenomenon. 相似文献
22.
23.
Luiz Francisco Fontana João Graciano Mendonça Filho 《Marine pollution bulletin》2010,60(10):1674-1681
The aim of this work was to quantify the biopolymers associated to esterase enzymes and identify bacterial respiratory activity in four cores collected in Suruí Mangrove, Guanabara Bay - RJ. Biopolymer concentration was 1000 times lower than previously reported in the literature, indicating the need for creating and establishing eutrophication indicative rates and records compatible with tropical coastal systems. The biochemical representative relationships in the cores were equivalent to those from studies on coastal marine environments made in the Northern Hemisphere. The esterase enzymes in the sediment proved efficient in the mineralization of biopolymers, even with preferentially anaerobic metabolic physiology. Despite the lack of incipient geomicrobiological studies, the results highlighted the possible application of microbiology to a better understanding of geological processes. 相似文献
24.
Prey diversity of Homo sapiens in north Iberia exhibited shifts associated with climate warming after the Last Glacial Maximum, as deduced from animal remains obtained from Upper Palaeolithic caves in Asturias (northern Spain). Significant association of prey diversity and river proximity was found during adverse climate conditions, indicating opportunistic predation. A high increase of prey diversity was found when small animals (including fish) were taken into account in archaeological records, highlighting the importance of this type of prey in Palaeolithic diets. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
25.
An analysis was carried out of the secular period variation of four WU Ma type stars (AW UMa, AP Leo, AG Vir and AH Vir) using
some newly determined times of minima as well as others reported in the literature. It was found that two stars show period
increases, one a period decrease and the remaining shows no variation in period.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
26.
Jonathan Irwin Suzanne Aigrain Simon Hodgkin Keivan G. Stassun Leslie Hebb Mike Irwin Estelle Moraux Jerome Bouvier Aude Alapini Richard Alexander D. M. Bramich Jon Holtzman Eduardo L. Martín Mark J. McCaughrean Frédéric Pont P. E. Verrier María Rosa Zapatero Osorio 《Monthly notices of the Royal Astronomical Society》2007,380(2):541-550
We present a general recipe for constructing N -body realizations of galaxies comprising near spherical and disc components. First, an exact spherical distribution function for the spheroids (halo and bulge) is determined, such that it is in equilibrium with the gravitational monopole of the disc components. Second, an N -body realization of this model is adapted to the full disc potential by growing the latter adiabatically from its monopole. Finally, the disc is sampled with particles drawn from an appropriate distribution function, avoiding local-Maxwellian approximations. We performed test simulations and find that the halo and bulge radial density profile very closely match their target model, while they become slightly oblate due to the added disc gravity. Our findings suggest that vertical thickening of the initially thin disc is caused predominantly by spiral and bar instabilities, which also result in a radial re-distribution of matter, rather than scattering off interloping massive halo particles. 相似文献
27.
Luis Floría 《Celestial Mechanics and Dynamical Astronomy》1997,68(1):75-85
We study the possibilities and limitations of the application of generalized Delaunay-like transformations (in the 6-dimensional
phase space) and TR-like mappings (in the 8-dimensional, extended phase space) to perturbed two-body problems with a time-varying
Keplerian parameter μ(t), that is, to Gylden-type systems. For the sake of theoretical completeness, both negative- and positive-energy
motion (with nonstationary coupling parameter) are, in principle, considered. Our developments are intended to introduce canonical
variables parallelling the classical ones of Delaunay and the Delaunay-Similar variables of Scheifele.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
28.
P.J. Arango A. Devia A.F. Rojas C.A. Peña J.A. Ortiz E. Restrepo 《Astrophysics and Space Science》1997,256(1-2):517-521
We have been studying direct current glow discharges aiming at the production of different paint of coatings on steel substrates. In a set of preliminary experiments, long lasting (hours) discharges performed in a Nitrogen atmosphere between a stell anode (holding the substrates) and a titanium cathode separated by a small gap (few mm) produced very thin coatings of the substrates whose colour depend on the parameter of (interelectrodes gap, gas pressure, discharge current and time duration). In some conditions, the coatings showed a golden colour, typical of the Nti compound. A discussion of the results is given. 相似文献
29.
Bernardo Cesare Daniela Rubatto María Teresa Gómez-Pugnaire 《Contributions to Mineralogy and Petrology》2009,157(2):267-279
The high-K calc-alkaline volcanic rocks along the Neogene Volcanic Province of SE Spain represent crustal anatectic melts mixed with mantle components during the opening of the Alborán Sea. Partially melted metapelitic enclaves, along with the geochemical signature, provide evidence of their crustal source. U–Pb SHRIMP geochronology on monazite and zircon from enclaves and their hosting lavas in the localities of El Hoyazo, Mazarrón and Mar Menor reveals variable delays between the melting at depth and the eruption of the volcanics. These data indicate that: (1) the most important event of anatexis in the Neogene spanned at least the 3 m.y. interval between 12 and 9 Ma; (2) there is no trend in age of crustal melting; and (3) the delay between magma generation and extrusion varies from more than 3 m.y. at El Hoyazo to ~0.5 m.y. and possibly 2.5 m.y. at Mar Menor, with no significant delay measurable at Mazarrón. The variable time delay between anatexis and lava extrusion indicates that radiometric ages of volcanics may provide misleading information on the timing of magma genesis occurring at depth. This highlights the pitfall of basing detailed geodynamic models on volcanic extrusion ages alone. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
30.
Francisco González-Sánchez Antoni Camprubí Eduardo González-Partida Rafael Puente-Solís Carles Canet Elena Centeno-García Viorel Atudorei 《Mineralium Deposita》2009,44(3):343-361
Northeastern Mexico hosts numerous epigenetic stratabound carbonate-hosted low-temperature hydrothermal deposits of celestine, fluorite, barite and zinc-lead, which formed by replacement of Mesozoic evaporites or carbonate rocks. Such deposits can be permissively catalogued as Mississippi Valley-type (MVT) deposits. The deposits studied in the state of Coahuila are associated with granitic and metasedimentary basement highs (horsts) marginal or central to the Mesozoic Sabinas Basin. These horsts controlled the stratigraphy of the Mesozoic basins and subsequently influenced the Laramide structural pattern. The Sabinas Basin consists of ~6,000-m-thick Jurassic to Cretaceous siliciclastic, carbonate and evaporitic series. The MVT deposits are mostly in Barremian and in Aptian-Albian to Cenomanian formations and likely formed from basinal brines that were mobilized during the Laramide orogeny, although earlier diagenetic replacement of evaporite layers (barite and celestine deposits) and lining of paleokarstic cavities in reef carbonates (Zn–Pb deposits) is observed. Fluid inclusion microthermometry and isotopic studies suggest ore formation due to mixing of basinal brines and meteoric water. Homogenization temperatures of fluid inclusions range from 45°C to 210°C; salinities range from 0 to 26 wt.% NaCl equiv., and some inclusions contain hydrocarbons or bitumen. Sulfur isotope data suggest that most of the sulfur in barite and celestine is derived from Barremian to Cenomanian evaporites. Regional geology and a compilation of metallogenic features define the new MVT province of northeastern Mexico, which comprises most of the state of Coahuila and portions of the neighboring states of Nuevo León, Durango and, perhaps extends into Zacatecas and southern Texas. This province exhibits a regional metal zonation, with celestine deposits to the south, fluorite deposits to the north and barite and Zn–Pb deposits mostly in the central part. 相似文献