On some amphicorina (polychaeta, sabellidae) species from the mediterranean coast, with the description of A. grahamensis

Species belonging to the genus Amphicorina are reported from some areas of the Mediterranean Sea, with the description of the new species A. grahamensis. The description of another species, Amphicorina sp., close to an Australian taxon, together with the redescriptions of A. pectinata, A. persinosa, and A. armandi are also given; the variability of this last taxon, probably deriving from misidentiflcations, is also considered. Examined specimens were prevalently from the Italian coast, and in particular from the Adriatic Sea. © 1999 Taylor & Francis Group, LLC

Sperm ultrastructure and spermiogenesis in two Exogone species (Polychaeta, Syllidae, Exogoninae)

The spermatozoa of Exogone naidina and E. dispar are characterized by a prominent bell-shaped acrosome, a spheroidal nucleus, and a conventional flagellum. During spermiogenesis, the acrosomal vesicle undergoes conspicuous modifications leading to its final bell shape with a posterior opening. The subacrosomal material initially shows radiating filaments but in mature sperms it appears as a meshwork of electron-opaque material. The acrosomal axis is oblique with respect to the main longitudinal sperm axis. The chromatin is arranged in electronopaque strands in the early spermatids, then becomes amorphous, and is finally organized in filaments in mature sperms. Centrioles are orthogonally arranged beneath the nucleus and fibers radiate from the distal centriole to contact the plasma membrane and the single mitochondrion. The latter is located eccentrically on the side of the nucleus opposite the acrosome. A disk-shaped structure is evident beneath the distal centriole. The flagellar axoneme has a 9+2 microtubule pattern. A conspicuous glycocalyx surrounds the flagellar plasma membrane, and an electron-lucent space is present between these two structures at the distal tip of the flagellum. We compare the sperm morphology of these two species of Exogone with that described in other members of the subfamily Exogoninae. The fine structure of these two species supports the occurrence of an ent-aquasperm type within Exogoninae, in accordance with the brood strategy present within this subfamily. The mode of reproduction is of taxonomic importance for defining subfamilies within Syllidae, and is likely also of phylogenetic significance. Because epitoky is probably plesiomorphic, the ent-aquasperm type found in Exogoninae can be considered a derived feature within Syllidae

J Vis Exp

The last decades have witnessed the explosion of scientific interest around gene expression control mechanisms at the RNA level. This branch of molecular biology has been greatly fueled by the discovery of noncoding RNAs as major players in post-transcriptional regulation. Such a revolutionary perspective has been accompanied and triggered by the development of powerful technologies for profiling short RNAs expression, both at the high-throughput level (genome-wide identification) or as single-candidate analysis (steady state accumulation of specific species). Although several state-of-art strategies are currently available for dosing or visualizing such fleeing molecules, Northern Blot assay remains the eligible approach in molecular biology for immediate and accurate evaluation of RNA expression. It represents a first step toward the application of more sophisticated, costly technologies and, in many cases, remains a preferential method to easily gain insights into RNA biology. Here we overview an efficient protocol (Enhanced Northern Blot) for detecting weakly expressed microRNAs (or other small regulatory RNA species) from Drosophila melanogaster whole embryos, manually dissected larval/adult tissues or in vitro cultured cells. A very limited amount of RNA is required and the use of material from flow cytometry-isolated cells can be also envisaged

Evaluation of strand-to-strand capacitance and dissipation factor in thermally aged enamelled coils for low-voltage electrical machines

© The Institution of Engineering and Technology 2019. The dissipation factor (i.e. tanδ) and insulation capacitance (IC) measurements are conventional monitoring methods for assessing the aging level of insulation systems. These quantities provide an invaluable indication of the dielectric losses within the insulating materials. However, how these values are affected by the aging processes due to thermal stresses have until today never been investigated fully. Thus, this study exhibits the influence of thermal aging on tanδ and IC of windings for electrical machines (EMs). The work is performed for class 200, round enamelled magnet wire specimens. The study aims at improving the design process of EMs for short duty cycle applications; hence, its outcome might be included at the design stage for enhancing reliability and lifetime. Random wound coils are chosen in the performed study, because they are the most common winding arrangement for low-voltage EMs, which are employed in a wide range of applications (e.g. from home appliances to aerospace motors). Based on the collected data, considerations regarding the impact of relative humidity on both the dissipation factor and IC are presented. Finally, the correlation between the partial discharge inception voltage and the diagnostic measurements is experimentally verified

Іконографічні особливості образу Богородиці в східній християнській традиції: релігієзнавчий аспект

Стаття присвячена аналізу іконографічних особливостей образу Богородиці в православній традиції. Розглянуто особливості іконографічного зображення, його відмінність від зображення у творі мистецтва. Проаналізовано чотири основні іконографічні типи й варіанти ікон Богородиці. Показано, що характерною рисою всіх типів ікон Богородиці є їхня христоцентричність та самостійність як духовного атрибута богоспілкування.In the article is analyzed the iconographic features of the Virgin in the Orthodox tradition. The author argues that Christocentric is the main characteristic of the icons of the Virgin

External gestation of Exogone naidina Öersted, 1845 (Polychaeta, Syllidae): Ventral attachment of eggs and embryos

The external gestation of sexually ripe females of the species Exogone naidina (Polychaeta, Syllidae) is described by means of SEM and TEM analysis. The eggs, embryos and juveniles are attached in close vicinity of each parapodial complex in a position immediately below each ventral cirrus and are connected to the female by a cup like structure. The formation of this adhesive disk is linked to secretory cells scattered between dermal cells of ripe female. This adhesive disk is present only in sexually mature animals and is considered as epitokous structure. The evolutive significance of ventral and dorsal attachment found within the Exogoninae is also discussed. © 2003 Elsevier Ltd. All rights reserved

Design and testing of disconnection actuators for enhancing safety and preventing failure escalation

The growing demand for reliability has led to an increased interest in developing effective disconnection systems for enhancing the safety of and preventing failure escalation in engineering systems. Considering this prospect, the design optimization of two disconnection actuators composed of a coaxial magnetic coupling linked to an electromagnetic device is presented and discussed. The disconnection actuator delivers a contactless torque transmission through the coaxial magnetic coupling, whereas the torque transfer is interrupted by the electromagnetic device in case a failure is detected via a dedicated algorithm. The performed design procedure relies on 2D finite element analysis, and trade-off studies are carried out to achieve an optimized geometry of an electromagnetic device. Finally, two disconnection actuators, for high-speed and high-torque applications, are prototyped and tested, with the aim of evaluating their disconnection capability. For both disconnection actuators, the developed force and voltage–current characteristics are measured along with the disconnection time