1,721,182 research outputs found
Charge transport models for amorphous chalcogenides
No full textThe chapter addresses the issue of transport models applied to the
amorphous chalcogenides which, in the last decades, have acquired
importance in the design and manufacture of solid-state memories. After
an introductory part where the main properties of the materials are
outlined, ab initio atomistic, and semiclassical computational approaches
for the study of the atomic structure and the features of electronic states
of chalcogenides are briefly illustrated. This part is concluded by a
description of the resistance-drift phenomenon and of how the simulation
approaches contributed to the comprehension of the underlying physics.
The successive section summarizes a variety of physical models
and numerical methods useful for describing charge transport in the
materials. The issue is developed in the two subsequent sections,
dealing with microscopic and macroscopic models, respectively. The
first section of the pair addresses the trap-limited transport model in the
hydrodynamic form and discusses a 3D network of randomly placed
traps. Specific issues, like detrapping due to electron-electron interaction
and the probability of inter-trap transitions, are addressed here. Finally,
ab initio quantum models for ultrascaled devices are illustrated
Nomenclatural Acts: homonymy in the Ascidiacea (Tunicata) and proposed nomina nova
No full textBrunetti, R. (2007): Nomenclatural Acts: homonymy in the Ascidiacea (Tunicata) and proposed nomina nova. Zootaxa 1613 (1): 67-68, DOI: 10.11646/zootaxa.1613.1.5, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.1613.1.
Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea
No full textBrunetti, R., Mastrototaro, F. (2012): Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea. Zootaxa 3258 (1): 28-36, DOI: 10.11646/zootaxa.3258.1.2, URL: https://biotaxa.org/Zootaxa/article/view/zootaxa.3258.1.
FIGURE 6. Botrylloides pizoni n in Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea
No full textFIGURE 6. Botrylloides pizoni n. sp. a, cross section of a "mammillated" colony; b, enlarged detail from fig a: oa = oral apertures of zooids, cc = cloacal canal. Scale bars: a, 6 mm; b, 500 µm.Published as part of Brunetti, R. & Mastrototaro, F., 2012, Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea, pp. 28-36 in Zootaxa 3258 (1) on page 35, DOI: 10.11646/zootaxa.3258.1.2, http://zenodo.org/record/524926
FIGURE 4. Botrylloides pizoni n in Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea
No full textFIGURE 4. Botrylloides pizoni n. sp. a1, and a2, parietal and mesial sides of intestine; b, swimming larva. Scale bars: a1 and a2, 300 µm; b: 600 µm.Published as part of Brunetti, R. & Mastrototaro, F., 2012, Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea, pp. 28-36 in Zootaxa 3258 (1) on page 33, DOI: 10.11646/zootaxa.3258.1.2, http://zenodo.org/record/524926
The non-indigenous ascidian Distaplia bermudensis in the Mediterranean: comparison with the native species Distaplia magnilarva and Distaplia lucillae sp. Nov
No full textThree species of Distaplia from the Mediterranean are described: D. bermudensis is a species introduced
from the western Atlantic Ocean, which principally di¡ers from the native D. magnilarva in having
hermaphroditic zooids. The new species D. lucillae di¡ers from the preceding ones in the structure of its
stomach wall which is regularly plicated both externally and internally. Distaplia lucillae has colonies with
hermaphroditic, but only male ripe, zooids and exclusively female colonies; this is a condition closely
related to D. magnilarva though di¡erent. A key to European Distaplia is provided
Botrylloides pizoni, a new species of Botryllinae (Ascidiacea) from the Mediterranean Sea
No full textA new ascidian species belonging to the Botryllinae was discovered in the Gulf of Taranto (South Italy). This new species was collected in different seasons over a period of several years, which allowed information about its biology to be obtained. The new species presents large zooids arranged in ladder systems. The zooids have several rows of stigmata, the second one complete, ovary posterior to testis, one larva per side developing in an incubatory pouch, and a peculiar arrangement of the gut loop. The new species is named Botrylloides pizoni after the great French zoologist Antoine Pizon (1860-1942). Copyright © 2012 Magnolia Press
Phallusia ingeria Trausdedt, 1883: morphology and development (Ascidiacea, Tunicata)
No full textAbundant populations of the phlebobranch ascidian Phallusia ingeria Traustedt, 1883 previously only sporadically reported in the Mediterranean Sea, have been found in the Lagoon of Venice, allowing a description of its macroscopic and microscopic morphology and in vivo observation of its development from hatching to maturation. The body may be up to 4 cm high. The test shows pointed papillae in which the terminal ampullae of the test vascular system formed of characteristic paired vessels end. The prebranchial and epibranchial areas are densely papillated. The dorsal tubercle is small, and several openings of the neural duct are found in the atrial cavity. The branchial sac of the larger animals shows intermediate papillae and parastigmatic vessels. The dorsal lamina is ribbed on both sides and toothed at the edge. In large animals, it has papillae on right side. The stomach is irregularly plicated. The anus is posterior to the pole of the gut loop. Microscopic morphology was studied on serial sections (7 m). Development was studied in animals obtained by artificial fertilisation, reared in the laboratory. At 18°C, maturity
is reached in 180 days, when the animals are about 10 mm height
The non-indigenous stolidobrach ascidian Polyandrocarpa zorritensis in the Mediterranean: description, larval morphology and pattern of vascular budding
No full textThe stolidobranch ascidian Polyandrocarpa zorritensis was detected, for the third time in the Mediterranean,
in the harbour of Taranto (South Italy). Colonies develop vigorously on all hard substrata
in shallow water and now represent one of the most important elements of the local fouling
community. In this article specimens of the Mediterranean populations of the species are described.
The morphology of the larva, which differs from that of other Polyzoinae, and a vascular budding
mechanism of replication, similar to that known to occur in the Botryllinae, were both observed for
the first time
The Semiconductor Model Solved by the Numerov Process over a Non-Uniform Grid
No full textThe Numerov Process (NP) provides the solution of some classes of ODEs with an accuracy much superior to that of the standard finite-difference or box-integration methods. The original formulation of NP requires a uniform grid, which is a drawback for applications to, e.g., the semiconductor-device equations. Purpose of this work is showing how a method for extending NP to a non-uniform grid is applied to the solution of the drift-diffusion model. The method keeps the fifth-order accuracy of the original NP. In the multi-dimensional case, the variable transformation illustrated in the paper is found beneficial also when standard solution schemes are used; in fact, it makes the current-density vector well defined within each grid element
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