2,126 research outputs found
Three Oligochaeta, Glossoscolecidae from Amazonia
The animals were collected in the igapó of the Tarumâ MirÃm River (03° 02'S, 60° 17'W), near Manaus, Brazil. Diachaeta (D.) adisi, sp. n. and D. (Amazo) arawak, sp. n. are described. Tuiba tipema is interpreted as a synonym of T. dianae
High-energy neutrinos from FR0 radio-galaxies?
The sources responsible for the emission of high-energy ( 100 TeV)
neutrinos detected by IceCube are still unknown. Among the possible candidates,
active galactic nuclei with relativistic jets are often examined, since the
outflowing plasma seems to offer the ideal environment to accelerate the
required parent high-energy cosmic rays. The non-detection of single point
sources or -- almost equivalently -- the absence, in the IceCube events, of
multiplets originating from the same sky position, constrains the cosmic
density and the neutrino output of these sources, pointing to a numerous
population of faint sources. Here we explore the possibility that FR0
radiogalaxies, the population of compact sources recently identified in large
radio and optical surveys and representing the bulk of radio-loud AGN
population, can represent suitable candidates for neutrino emission. Modeling
the spectral energy distribution of a FR0 radiogalaxy recently associated to a
-ray source detected by the Large Area Telescope onboard Fermi, we
derive the physical parameters of its jet, in particular the power carried by
it. We consider the possible mechanisms of neutrino production, concluding that
reactions in the jet between protons and ambient radiation is too
inefficient to sustain the required output. We propose an alternative scenario,
in which protons, accelerated in the jet, escape from it and diffuse in the
host galaxy, producing neutrinos as a result of scattering with the
interstellar gas, in strict analogy with the processes taking place in
star-forming galaxies.Comment: 5 pages, 3 figures, accepted for publication in MNRA
Andiorrhinus (Amazonidrilus) motto n. sp. and Rhinodrilus appuni pavoni n. subsp. (Oligochaeta, Glossoscolecidae) frorn the Venezuelan Amazonia
The two species presented herein were collected in Venezuela, Amazonas State and studied by dissection and serial histological section. Andiorrhinus (Amazonidrilus) motto n. sp. is characterised by the size, male genital field and spermathecal apparatus. Rhinodrilusappunipavoni n. subsp. has two pairs of peculiar prostatoid glands united in a cushion on either side.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Amazonia, Anatomy, Taxonomy.The two species presented herein were collected in Venezuela, Amazonas State and studied by dissection and serial histological section. Andiorrhinus (Amazonidrilus) motto n. sp. is characterised by the size, male genital field and spermathecal apparatus. Rhinodrilusappunipavoni n. subsp. has two pairs of peculiar prostatoid glands united in a cushion on either side.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Amazonia, Anatomy, Taxonomy.The two species presented herein were collected in Venezuela, Amazonas State and studied by dissection and serial histological section. Andiorrhinus (Amazonidrilus) motto n. sp. is characterised by the size, male genital field and spermathecal apparatus. Rhinodrilusappunipavoni n. subsp. has two pairs of peculiar prostatoid glands united in a cushion on either side.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Amazonia, Anatomy, Taxonomy
Three new species and new records of Oligochaeta, Glossoscolecidae, from the Venezuelan Andes
Five species of Oligochaeta, Glossoscolecidae, from Venezuela, Merida State (1,500 to 4,350 m a.s.1.) were studied by dissection and serial microscopical sections. Andiorrhinus (Amazonidrilus) gavi n. sp. is characterized by the space aa wider in XX-XXIII and seven pairs of hearts in VII-XIII. A. (Meridrilus) rimeda, n. sp. is notable for the pair of puberal bands lateral do b in XX-XXIII flanked by two longitudinal cords. Rhinodrilus mucuba, n. sp. has a typical arrangement of the setae and spermathecae. New observations are reported for the previously known Onychochaeta windlei and A. (M.) kuika; the variability of the latter species is recorded.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Andes, Taxonomy.Five species of Oligochaeta, Glossoscolecidae, from Venezuela, Merida State (1,500 to 4,350 m a.s.1.) were studied by dissection and serial microscopical sections. Andiorrhinus (Amazonidrilus) gavi n. sp. is characterized by the space aa wider in XX-XXIII and seven pairs of hearts in VII-XIII. A. (Meridrilus) rimeda, n. sp. is notable for the pair of puberal bands lateral do b in XX-XXIII flanked by two longitudinal cords. Rhinodrilus mucuba, n. sp. has a typical arrangement of the setae and spermathecae. New observations are reported for the previously known Onychochaeta windlei and A. (M.) kuika; the variability of the latter species is recorded.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Andes, Taxonomy.Five species of Oligochaeta, Glossoscolecidae, from Venezuela, Merida State (1,500 to 4,350 m a.s.1.) were studied by dissection and serial microscopical sections. Andiorrhinus (Amazonidrilus) gavi n. sp. is characterized by the space aa wider in XX-XXIII and seven pairs of hearts in VII-XIII. A. (Meridrilus) rimeda, n. sp. is notable for the pair of puberal bands lateral do b in XX-XXIII flanked by two longitudinal cords. Rhinodrilus mucuba, n. sp. has a typical arrangement of the setae and spermathecae. New observations are reported for the previously known Onychochaeta windlei and A. (M.) kuika; the variability of the latter species is recorded.
Key words: Oligochaeta, Glossoscolecidae, Venezuela, Andes, Taxonomy
Ab Initio Calculation of the Adhesion and Ideal Shear Strength of Planar Diamond Interfaces with Different Atomic Structure and Hydrogen Coverage
n/
Belladrilus (Santomesia) auka n. sp. (Oligochaeta, Ocnerodrilidae) from Argentina
From Cordoba Province, Argentina the Ocnerodrilidae Belladrilus (Santomesia) auka n. sp. is described by dissections and serial histological sections. The species is well characterised by the tumid T-shaped male porophore in XVll with an anterior half-moon depression and a posterior cross thickening. The seminal grooves are convergent and thin in the anterior half, straight and wider in the posterior half.
Key words: Oligochaeta, Ocnerodrilidae, Cordoba, Argentina, Anatomy, Taxonomy.From Cordoba Province, Argentina the Ocnerodrilidae Belladrilus (Santomesia) auka n. sp. is described by dissections and serial histological sections. The species is well characterised by the tumid T-shaped male porophore in XVll with an anterior half-moon depression and a posterior cross thickening. The seminal grooves are convergent and thin in the anterior half, straight and wider in the posterior half.
Key words: Oligochaeta, Ocnerodrilidae, Cordoba, Argentina, Anatomy, Taxonomy.From Cordoba Province, Argentina the Ocnerodrilidae Belladrilus (Santomesia) auka n. sp. is described by dissections and serial histological sections. The species is well characterised by the tumid T-shaped male porophore in XVll with an anterior half-moon depression and a posterior cross thickening. The seminal grooves are convergent and thin in the anterior half, straight and wider in the posterior half.
Key words: Oligochaeta, Ocnerodrilidae, Cordoba, Argentina, Anatomy, Taxonomy
Singling out the effect of quenched disorder in the phase diagram of cuprates
We investigate the specific influence of structural disorder on the
suppression of antiferromagnetic order and on the emergence of cuprate
superconductivity. We single out pure disorder, by focusing on a series of
YEuBaCuO samples at fixed oxygen content
, in the range . The gradual Y/Eu isovalent substitution
smoothly drives the system through the Mott-insulator to superconductor
transition from a full antiferromagnet with N\'eel transition K at
to a bulk superconductor with superconducting critical temperature
K at , YBaCuO. The electronic properties are
finely tuned by gradual lattice deformations induced by the different cationic
radii of the two lanthanides, inducing a continuous change of the basal Cu(1)-O
chain length, as well as a controlled amount of disorder in the active
Cu(2)O bilayers. We check that internal charge transfer from the basal to
the active plane is entirely responsible for the doping of the latter and we
show that superconductivity emerges with orthorhombicity. By comparing
transition temperatures with those of the isoelectronic clean system we
deterime the influence of pure structural disorder connected with the Y/Eu
alloy.Comment: 10 pages 11 figures, submitted to Journal of Physics: Condensed
Matter, Special Issue in memory of Prof. Sandro Massid
Ab initio study on the surface chemistry and nanotribological properties of passivated diamond surfaces
Experimental findings indicate that the impressively low friction and wear of diamond in humid environments are determined by the surface passivation. In this paper, we investigate the relationship between the surface chemistry and the nanotribological properties of diamond surfaces. We consider the (2x1)-C(001) surface taking into account different terminations constituted of hydrogen, oxygen, and hydroxyl groups. We analyze the adsorbate geometry and the polarization of the surface bonds. We discuss the stability of the different surface terminations in different conditions, which account for the presence in the environment of H-2, O-2, and H2O molecules in different concentrations and we present the surface phase diagram. Finally, we report the calculated adhesion energy between the passivated surfaces and analyze its variation as a function both of the surface separation and of the surface relative lateral position. In this way, we provide information on the effect of the different adsorbates on the interaction between diamond surfaces and on the magnitude and anisotropy of friction forces
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