Consumption of bacteria by larvae of a deep-sea polychaete     

Adele J. Pile  & Craig M. Young 《Marine Ecology》2006,27(1):15-19

We investigated whether trochophore larvae of the polychaete Hesiocaeca methanicola, which lives on exposed ice‐like methane hydrates between 500 and 600 m, could consume near‐bottom picoplankton. In laboratory trials larvae significantly reduced the growth rates of all types of picoplankton, including heterotrophic bacteria, Prochlorococcus sp., Synechococcus‐type cyanobacteria and phototrophic eucaryotes <3 μm. Our findings suggest that these types of plankton may be important food sources for deep‐sea planktotrophic larvae.  相似文献   

Multispecies dendroclimatic reconstructions of summer temperature in the European Alps enhanced by trees highly sensitive to temperature     

Giovanni Leonelli  Anna Coppola  Carlo Baroni  Maria Cristina Salvatore  Maurizio Maugeri  Michele Brunetti  Manuela Pelfini 《Climatic change》2016,137(1-2):275-291

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Equilibrium temperatures of interstellar iron grains     

Ronald G. Tabak  Adele K. Straitiff 《Astrophysics and Space Science》1983,93(1):199-206

Because of the relatively low number densities found in typical interstellar clouds, molecules observed there must be produced by a combination of both two-body gas-phase reactions and surface reactions. The latter type includes various catalytic reactions, such as the formation of H₂ on transition metal grains. These reactions are very temperature dependent, the grain temperature appearing in the exponential of the rate equations. Because of the small heat capacities of the grains due to their small sizes, they may be subject to considerable fluctuations in temperature. This problem is examined for iron grains and found to be minimal for sizes greater than 100 Å. Steady-state equilibrium temperatures are then calculated for a size distribution of iron particles ranging from 10³ to 10⁹ atoms per grain by a refined method of an earlier work by one of us (RGT). The results are that iron grain temperatures are significantly greater than those of dielectric grains of comparable size in the same radiation field.  相似文献   

Compressible turbulence in galaxy clusters: physics and stochastic particle re-acceleration     

G. Brunetti  A. Lazarian 《Monthly notices of the Royal Astronomical Society》2007,378(1):245-275

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Spatial variability of maximum and minimum monthly temperature in Spain during 1981–2010 evaluated by correlation decay distance (CDD)     

D. Pena-Angulo  N. Cortesi  M. Brunetti  J. C. González-Hidalgo 《Theoretical and Applied Climatology》2015,122(1-2):35-45

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Massive and refined: A sample of large galaxy clusters simulated at high resolution. I: Thermal gas and properties of shock waves     

F. Vazza  G. Brunetti  C. Gheller  R. Brunino 《New Astronomy》2010,15(8):695-711

We present a sample of 20 massive galaxy clusters with total virial masses in the range of 6 × 10¹⁴ M_⊙ ? M_vir ? 2 × 10¹⁵ M_⊙, re-simulated with a customized version of the 1.5. ENZO code employing adaptive mesh refinement. This technique allowed us to obtain unprecedented high spatial resolution (≈25 kpc/h) up to the distance of ～3 virial radii from the clusters center, and makes it possible to focus with the same level of detail on the physical properties of the innermost and of the outermost cluster regions, providing new clues on the role of shock waves and turbulent motions in the ICM, across a wide range of scales.In this paper, a first exploratory study of this data set is presented. We report on the thermal properties of galaxy clusters at z = 0. Integrated and morphological properties of gas density, gas temperature, gas entropy and baryon fraction distributions are discussed, and compared with existing outcomes both from the observational and from the numerical literature. Our cluster sample shows an overall good consistency with the results obtained adopting other numerical techniques (e.g. Smoothed Particles Hydrodynamics), yet it provides a more accurate representation of the accretion patterns far outside the cluster cores. We also reconstruct the properties of shock waves within the sample by means of a velocity-based approach, and we study Mach numbers and energy distributions for the various dynamical states in clusters, giving estimates for the injection of Cosmic Rays particles at shocks. The present sample is rather unique in the panorama of cosmological simulations of massive galaxy clusters, due to its dynamical range, statistics of objects and number of time outputs. For this reason, we deploy a public repository of the available data, accessible via web portal at http://data.cineca.it.  相似文献   

Polar wander on Mars: Evidence in the geoid     

Kenneth F. Sprenke  Leslie L. Baker  Adele F. Williams 《Icarus》2005,174(2):486-489

The geoid of Mars is dominated by its equilibrium figure and by the effect of the Tharsis rise. To investigate the rotational stability of Mars prior to the rise of Tharsis, we produced a residual non-hydrostatic geoid without Tharsis. First the hydrostatic component of the present-day flattening was removed. This procedure was performed using a 6% non-hydrostatic component of flattening, a value set by the spin axis precession rate of Mars. Then zonal spherical harmonics up to degree 6 centered on Tharsis were removed. Finally, the resultant residual geoid was evaluated for rotational stability by comparing polar and equatorial moments at 4050 trial pole positions. If the spin axis of ancient Mars was secularly stable, our analysis indicates that substantial polar wander has occurred with the rise of Tharsis. Stable spin axis positions on the non-hydrostatic residual figure of Mars are 15° to 90° from the present-day poles. This result is consistent with previously proposed paleopoles based on magnetic anomalies, geomorphology, and grazing impacts.  相似文献   

A Moon orbiting observatory for the measurement of the elemental and isotopic composition in the primary cosmic radiation     

A. Codino  M. T. Brunetti  A. Coradini  C. Federico  C. Grimani  T. Macchiaiolo  M. Menichelli  G. Minelli  M. Miozza  F. Plouin 《Astrophysics and Space Science》1994,220(1):131-147

We describe a project for the measurement of elemental composition of the primary cosmic radiation to be performed by a space observatory orbiting around the Moon. The absence of atmosphere and the low intrinsic magnetic field of the Moon give access to the very low energy component of the cosmic radiation, allowing the search for rare events.The quest for antinuclei, the determination of the lunar lepton albedo and the abundance measurement of galactic radioactive clocks (Be¹⁰, C¹⁴, Al²⁶) are the major tasks of the ANTARES apparatus (ANTimatter Assessment RESearch).We report details of the instrument design, the expected performance for single detectors, their capability to accomplish the proposed measurements and the characteristics of the space mission.  相似文献   

In-situ particle acceleration in extragalactic radio hot spots: observations meet expectations   总被引：1，自引：0，他引：1  

G. Brunetti  K.-H. Mack  M. A. Prieto  S. Varano 《Monthly notices of the Royal Astronomical Society》2003,345(3):L40-L44

We discuss, in terms of particle acceleration, the results from optical VLT observations of hot spots associated with radio galaxies. On the basis of observational and theoretical grounds, the following is shown. (i) Relatively low radio-radio power hot spots are the optimum candidates for being detected at optical waves. This is supported by an unprecedented optical detection rate of 70 per cent out of a sample of low radio power hot spots. (ii) The shape of the synchrotron spectrum of hot spots is mainly determined by the strength of the magnetic field in the region. In particular, the break frequency, related to the age of the oldest electrons in the hot spots, is found to increase with decreasing synchrotron power and magnetic field strength. Both observational results are in agreement with an in-situ particle acceleration scenario.  相似文献   

Coronal rotation dependence on the solar cycle phase     

Ester Antonucci  Maria Adele Dodero 《Solar physics》1977,53(1):179-188

A study of the green corona rotation rate, during the period 1970–1974, confirms that the differential rotation degree varies systematically through a solar cycle and that the corona rotates in an almost rigid manner before sunspot minimum. During the first two years, 1970–1971, the differential rotation degree, characteristic of high solar activity periods is detected. While during the years of declining activity, 1972–1974, a drastic decrease of the differential rotation degree occurs and the green corona rotates almost rigidly, as the coronal holes observed in the same period. These conclusions are valid only for the rotation of coronal features with lifetime of at least one solar rotation.  相似文献