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

Nanoscopic processes of Current Induced Switching in thin tunnel junctions

In magnetic nanostructures one usually uses a magnetic field to commute between two resistance (R) states. A less common but technologically more interesting alternative to achieve R-switching is to use an electrical current, preferably of low intensity. Such Current Induced Switching (CIS) was recently observed in thin magnetic tunnel junctions, and attributed to electromigration of atoms into/out of the insulator. Here we study the Current Induced Switching, electrical resistance, and magnetoresistance of thin MnIr/CoFe/AlO$_x$/CoFe tunnel junctions. The CIS effect at room temperature amounts to 6.9% R-change between the high and low states and is attributed to nanostructural rearrangements of metallic ions in the electrode/barrier interfaces. After switching to the low R-state some electro-migrated ions return to their initial sites through two different energy channels. A low (high) energy barrier of $\sim$0.13 eV ($\sim$0.85 eV) was estimated. Ionic electromigration then occurs through two microscopic processes associated with different types of ions sites/defects. Measurements under an external magnetic field showed an additional intermediate R-state due to the simultaneous conjugation of the MR (magnetic) and CIS (structural) effects.Comment: 6 pages, 4 figure

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

Comparison between the Torquato-Rintoul theory of the interface effect in composite media and elementary results

We show that the interface effect on the properties of composite media recently proposed by Torquato and Rintoul (TR) [Phys. Rev. Lett. 75, 4067 (1995)] is in fact elementary, and follows directly from taking the limit in the dipolar polarizability of a coated sphere: the TR ``critical values'' are simply those that make the dipolar polarizability vanish. Furthermore, the new bounds developed by TR either coincide with the Clausius-Mossotti (CM) relation or provide poor estimates. Finally, we show that the new bounds of TR do not agree particularly well with the original experimental data that they quote.Comment: 13 pages, Revtex, 8 Postscript figure

Refined Simulations of the Reaction Front for Diffusion-Limited Two-Species Annihilation in One Dimension

Extensive simulations are performed of the diffusion-limited reaction A$+$B$\to 0$ in one dimension, with initially separated reagents. The reaction rate profile, and the probability distributions of the separation and midpoint of the nearest-neighbour pair of A and B particles, are all shown to exhibit dynamic scaling, independently of the presence of fluctuations in the initial state and of an exclusion principle in the model. The data is consistent with all lengthscales behaving as $t^{1/4}$ as $t\to\infty$. Evidence of multiscaling, found by other authors, is discussed in the light of these findings.Comment: Resubmitted as TeX rather than Postscript file. RevTeX version 3.0, 10 pages with 16 Encapsulated Postscript figures (need epsf). University of Geneva preprint UGVA/DPT 1994/10-85

Cohomological characterizations of projective spaces and hyperquadrics

We confirm Beauville's conjecture that claims that if the p-th exterior power of the tangent bundle of a smooth projective variety contains the p-th power of an ample line bundle, then the variety is either the projective space or the p-dimensional quadric hypersurface.Comment: Added Lemma 2.8 and slightly changed proof of Lemma 6.2 to make them apply for torsion-free sheaves and not only to vector bundle

The Efroimsky formalism adapted to high-frequency perturbations

The Efroimsky perturbation scheme for consistent treatment of gravitational waves and their influence on the background is summarized and compared with classical Isaacson's high-frequency approach. We demonstrate that the Efroimsky method in its present form is not compatible with the Isaacson limit of high-frequency gravitational waves, and we propose its natural generalization to resolve this drawback.Comment: 7 pages, to appear in Class. Quantum Gra

Research note: The influence of micro-oxygenation on the long-term ageing ability of Pinot noir wine

In this study, Pinot noir wines were bottle aged for 12 and 18 months after micro-oxygenation (MOX) applied before or after malolactic fermentation (MLF) at two doses (10.8 and 52.4 mg/L/month). After ageing, a greater decrease in the total SO₂ concentration was found in wines with the higher MOX dosage, demonstrating a long-term impact of higher oxygen exposure on wines’ SO₂ requirement. Meanwhile, a negative impact of MOX on wine colour development occurred over time, resulting in a large loss of colour measures (i.e., 420 nm for brown hues, 520 nm for red colour, SO₂ resistant pigments, and colour intensity), which was greater with the early oxygen exposure. This was linked to a significantly lower content of large polymeric pigments in MOX treatments. Tannin concentration was, in the end, not affected by the MOX treatments. However, regarding tannin composition, considerably higher (-)-epicatechin extension units but much lower (-)-epicatechin terminal units were found with MOX treatments. In addition, a significant reduction of tannin trihydroxylation (%Tri-OH) but a higher galloylation (%Galloyl) and mean degree of tannin polymerisation (mDP) remained in wines with MOX, indicating a long-term negative influence on astringency intensity

Phase locking dynamics of dipolarly coupled vortex-based spin transfer oscillators

Phase locking dynamics of dipolarly coupled vortices excited by spin-polarized current in two identical nanopillars is studied as a function of the interpillar distance L. Numerical study and analytical model have proved the remarkable efficiency of magneto-static interaction to achieve phase locking. Investigating the dynamics in the transient regime towards phase locking, we extract the evolution of the locking time \tau, the coupling strength {\mu} and the interaction energy W. Finally, we compare this coupling energy with the one obtained by simple model.Comment: 4 pages, 4 figure