Neurophysiological control of swimming behaviour,attachment and metamorphosis in black-footed abalone (Haliotis iris) larvae     

AC Alfaro  T Young  K Bowden 《新西兰海洋与淡水研究杂志》2014,48(3):314-334

Experiments were conducted to test the effect of a range of chemicals on larval responses in swimming behaviour, attachment and metamorphosis of the black-footed abalone (Haliotis iris). The effect of antibiotics on larval survival was first tested within negative (filtered seawater) and positive (GABA at 10^?5, 10^?4 and 10^?3 mol L^?1) control assays over 3 days. This experiment corroborated the effectiveness of using antibiotics to improve survival of larvae without obvious synergistic interactions with the GABA inducer or confounding effects of potential bacterial interactions. Chemical treatments (acetylcholine, potassium chloride, dopamine and glutamine) were then tested at various concentrations for their ability to modulate swimming behaviour and induce larval attachment and metamorphosis over 14 days. Generally, larval state shifted from swimming to attached, and from attached to metamorphosed, in the control and treatments over time. However, the peak percentage of attached and metamorphosed larvae varied in time among chemicals and concentrations. While overall percent metamorphosis was minimally enhanced after 14 days of exposure to some chemical treatments at certain concentrations, all treatments displayed significant capacities to down-regulate larval swimming and induce early attachment and metamorphosis. Mortality was recorded throughout the duration of the experiment, and was generally low (<20%) across controls and most treatments for exposures of less than 12 days. Interpretations of specific results from this study are used to elucidate neurophysiological control of larval activities for this abalone species. Comparisons with other marine invertebrates highlight the specificities of chemical cues and endogenous regulatory mechanisms across relatively closely related taxa.  相似文献   

Energetic Particles Measured in and out of the Ecliptic Plane During the Last Gnevyshev Gap     

Rodríguez-Pacheco  J.  Blanco  J. J.  Heber  B.  Gómez-Herrero  R. 《Solar physics》2012,281(1):491-499

Solar Physics - We analyzed the temporal variation of energetic particles measured by the Low Energy Telescope (LET), the Kiel Electron Telescope (KET), and the High Energy Telescope (HET)...  相似文献   

CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories     

D. Gandolfi  M. Cigna  C. Blanco 《Planetary and Space Science》2009,57(1):1-1507

We present the results of observational campaigns of asteroids performed at Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro Station of Catania Astrophysical Observatory, as part of the large research programme on Solar System minor bodies undertaken since 1979 at the Physics and Astronomy Department of Catania University. Photometric observations of six Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and 984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199 Nefertiti and 2004 UE) are reported. The first determination of the synodic rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the derived synodic period of 80.23±0.08 and , respectively, represents a significant improvement on the previously published values. For 182 Elsa the first determination of the H-G magnitude relation is also presented.  相似文献   

Predation and competition effects on the size diversity of aquatic communities     

Xavier D. Quintana  Matías Arim  Anna Badosa  José María Blanco  Dani Boix  Sandra Brucet  Jordi Compte  Juan J. Egozcue  Elvira de Eyto  Ursula Gaedke  Stéphanie Gascón  Luis Gil de Solá  Kenneth Irvine  Erik Jeppesen  Torben L. Lauridsen  Rocío López-Flores  Thomas Mehner  Susana Romo  Martin Søndergaard 《Aquatic Sciences - Research Across Boundaries》2015,77(1):45-57

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Study of terrestrial fossils in phyllosilicate-rich soils: Implication in the search for biosignatures on Mars     

V. Orofino  A. Blanco  D. Licchelli  G.A. Marzo 《Icarus》2010,208(1):202-206

The search for biosignatures in the soil of Mars is a major objective of the planet exploration, but the detection of such structures is not straightforward due to the degradation of the organic material. In a previous work our group has analyzed the spectral reaction to thermal processing of biomineral carbonate samples including fresh and fossil shells. We found that two terrestrial fossil shells collected from clay deposits preserve their biomineral characteristics much better than coeval fossils not embedded in clay layers.In the present paper we extend our analysis to a set of fossils found in three different terrestrial clay deposits. Our results confirm that the level of degradation may be much lower than the standard values if fossils are surrounded by clay minerals. As a result these fossils have a spectroscopic response to thermal treatment which make them much more distinguishable from their abiotic counterparts than coeval fossils not collected from clay deposits. This result implies that the phyllosilicates regions recently discovered on Mars may represent very interesting environments that can provide conditions favorable to preserve evidence of biomarkers, and hence can be regarded as good candidate locations for their detection.  相似文献   

A new jadeitite jade locality (Sierra del Convento, Cuba): first report and some petrological and archeological implications   总被引：1，自引：1，他引：0  

Antonio García-Casco  A. Rodríguez Vega  J. Cárdenas Párraga  M. A. Iturralde-Vinent  C. Lázaro  I. Blanco Quintero  Y. Rojas Agramonte  A. Kröner  K. Núñez Cambra  G. Millán  R. L. Torres-Roldán  S. Carrasquilla 《Contributions to Mineralogy and Petrology》2009,158(1):1-16

A new jadeitite jade locality has been discovered in the serpentinite-matrix subduction mélange of the Sierra del Convento (eastern Cuba) in a context associated with tectonic blocks of garnet-epidote amphibolite, tonalitic–trondhjemitic epidote gneiss, and blueschist. The mineral assemblages of jadeitite jade and jadeite rocks are varied and include combinations of jadeite, omphacite, albite, paragonite, analcime, clinozoisite-epidote, apatite, phlogopite, phengite, chlorite, glaucophane, titanite, rutile, zircon, and quartz formed during various stages in their P–T evolution. Field relationships are obscure, but some samples made almost exclusively of jadeite show evidence of crystallization from fluid in veins. In one of these samples studied in detail jadeite shows complex textural and chemical characteristics (including oscillatory zoning) that denote growth in a changing chemical medium. It is proposed that interaction of an Al–Na rich fluid with ultramafic rocks produced Al–Na–Mg–Ca fluids of varying composition. Episodic infiltration of these fluids, as a result of episodic opening of the veins, developed oscillatory zoning by direct precipitation from fluid and after reaction of fluid with pre-existing jadeite. The latest infiltrating fluids were richer in Mg–Ca, favouring the formation of omphacite and Mg–Ca rich jadeite in open voids and the replacement of earlier jadeite by fine-grained omphacite + jadeite at 550–560°C. This new occurrence of jadeite in Cuba opens important perspectives for archeological studies of pre-Columbian jade artifacts in the Caribbean region.  相似文献   

Long-wave radiative analysis of cloudy scattering atmospheres using a net exchange formulation     

V. Eymet  J. L. Dufresne  P. Ricchiazzi  R. Fournier  S. Blanco 《Atmospheric Research》2004,72(1-4):239

The Net Exchange Formulation (NEF) is an alternative to the usual radiative transfer equation. It was proposed in 1967 by Green [Q. J. R. Meteorol. Soc. 93 (1967) 371] for atmospheric sciences and by Hottel [H.C. Hottel, A.F. Sarofim. Radiative Transfer McGraw Hill, New York, 1967] for engineering sciences. Until now, the NEF has been used only in a very few cases for atmospheric studies. Recently we have developed a long-wave radiative code based on this formulation for a GCM of the Mars planet. Here, we will present results for the Earth atmosphere, obtained with a Monte Carlo Method based on the NEF. In this method, fluxes are not addressed any more. The basic variables are the net exchange rates (NER) between each pair of atmospheric layer (i, j), i.e. the radiative power emitted by i and absorbed by j minus the radiative power emitted by j and absorbed by i. The graphical representation of the NER matrix highlights the radiative exchanges that dominate the radiative budget of the atmosphere and allows one to have a very good insight of the radiative exchanges. Results will be presented for clear sky atmospheres with Mid-Latitude Summer and Sub-Arctic Winter temperature profiles, and for the same atmospheres with three different types of clouds. The effect of scattering on long-wave radiative exchanges will also be analysed.  相似文献   

Volcanic hazards zonation of the Nevado de Toluca Volcano,Central Mexico     

José Fernando Aceves Quesada  Ana Lillian Martin Del Pozzo  Jorge López Blanco 《Natural Hazards》2007,41(1):159-180

Nevado de Toluca Volcano (NTV), located in central Mexico, is a large stratovolcano, with an explosive history. The area is one of the most important developing centers (>2 millions) in Mexico and in the last 30 yrs large population growth and expansion have increased the potential risk in case of a reactivation of the volcano. As part of a study to assess volcanic risk, this paper presents the results of the volcanic hazard analysis for the NTV. A total of 150 stratigraphic sections were made in the field and three new ages were obtained. Eruptions from NTV produced a complex sequence of pyroclastic deposits that have affected the area at least 18 times during the last 100,000 yrs. Eight vulcanian, four plinian and one-ultraplinian eruptions as well as the destruction of at least three domes occurred in the last 42,000 yr BP as well as two sector collapses in the last 100,000 yrs. Isopach and isopleth maps for the main ulraplinian eruption were also made. The original cone height (5,080 m.a.s.l) was reconstructed through geomorphologic methods. The maximum distance calculated with the energy line for the block and ash flows was 41 km, 35 km for pumice flows and 45 km for debris avalanches. The dominant wind direction at altitudes of 20–30 km is to the east-northeast from November to March, west-northwest in April and west from May to October. Five hazards maps (block and ash flows, pumice flows, ash fall, debris avalanches, and lahars) were made for the NTV. The pyroclastic flows and lahars represent very high to medium hazard for Toluca, Villa Guerrero, Coatepec, Tianguistengo, Metepec, Tenango, Lerma and Zinacantepec. A new debris avalanche would probably affect the south and northeast because of active faulting (E–W and NW–SE) and existing topographic differences in height.  相似文献   

Depth-dependent overtides from internal tide reflection in a glacial fjord     

Arnoldo Valle-Levinson  José Luis Blanco  Maximo Frangópulos 《Estuaries and Coasts》2007,30(1):127-136

Observations of current velocity profiles and hydrography over and near a tall sill in a Chilean glacial fjord are used to illustrate the interactions between barotropic and baroclinic tides. The character of the barotropic tide in the glacial fjord is mixed with semidiurnal dominance. The ratio of sill height to water column depth at the study site is ca. 0.95. Water column stratification appeared only in the upper 5 m of the water column. Current velocity variations in the stratified surface layer were quite different to those underneath. Below the pycnocline, nonlinear interactions between semidiurnal M₂ and diurnal K₁ oscillations yielded a third-diurnal distortion MK₃. Most interesting, surface layer currents were distortedby the superposition of semidiurnal M₂ and sixthdiurnal M₆ oscillations. The oscillations with M₆ variability were identified, through wave superposition approaches, as reflected internal tides linked to M₂ tidal variations. This was confirmed by theoretical results of stratified barotropic tidal flows interacting with abrupt bathymetry. Under the predominantly tidally mixed regime of the study area, the distortion to surface currents caused by the reflected wave was nearly symmetric during the large tidal ranges of the diurnal cycle. Nearly symmetric distortions resulted as the phase lag between incident and reflected wave-inducted currents was small (reflected currents developing a few minutes after maximum tidal flows). During the small ranges of the diurnal cycle, distortions were asymmetrical because of the relatively larger phase lags of the reflected signal (reflected currents developing tens of minutes after maximum tidal flows).  相似文献   

Rock coast inheritance: an example from Galicia,northwestern Spain     

A. S. Trenhaile  A. Prez Alberti  A. Martínez Cortizas  M. Costa Casais  R. Blanco Chao 《地球表面变化过程与地形》1999,24(7):605-621

A shore platform on the western coast of Galicia in northwestern Spain has been inherited from interglacial stages when sea level was similar to today. The wide, gently sloping intertidal platform is backed in places by supratidal rock ledges, and in other places by a steeper and narrower supratidal ramp. The gradient of the intertidal platform is consistent with the relationship between platform gradient and tidal range, but the slope of the ramp is much too high. The abandoned and degraded sea cliff is grass-covered along most of this coast, and the ledges and the ramp, which extend up to several metres above the highest tides, are covered by lichen and, in places, by salt-tolerant plants. Radiocarbon-dated sediments in the cliff, which range up to 36 000 years in age, lie on top of an ancient beach deposit. The former beach, remnants of which are found in situ on the ramp and rock ledges, as well as two caves that are filled with the dated sediments, are probably last interglacial in age. The morphological and sedimentary evidence suggests that the supratidal ramp and ledges were also formed during the last interglacial stage, whereas the wider intertidal platform is probably the product of several older interglacials, when sea level was generally similar to today. A general model is proposed for the inheritance of shore platforms in macro- and microtidal environments. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献