1,721,150 research outputs found
Neuronal aspects and plasticity of inferior olivary complex and nucleus dentatus
No full textIn primary or physiological ageing, the brain undergoes a 10% weight reduction. This datum was confirmed in vivo by radiological investigation and post mortem by morphological research (Grandi and Coll. 1990, 1990, 1991, 1991), that underscores the same reduction in the medulla oblongata and in the cerebellum. Morphological and cytohistological aspects of primary ageing have been considered for the inferior olivary nucleus and for the dentate nucleus in 41 male subjects, 32 belonging to the decades 7th, 8th, 9th, and 9 to the decades from the 3rd to the 6th. From the two latter structures, separated along standard cut surfaces, serial histological slices were carried out, and histochemical reactions were accomplished, together with immunohistochemistry, for synaptophysin, NF-2F11, NSE, S-100, GFAP, chromogranin. As the weight progressively decreased from the 7th to the 9th decade, it was noted neuronal loss, both in the inferior olivary nucleus, and in the dentate nucleus. Furthermore, the loss appeared to be followed by substitutive astroglial proliferation. Immunocytochemical reaction for synaptophysin revealed peculiar aspects. A consistently regular result of such method concerned the two nuclei studied, in primary ageing, thus allowing the interpretation of the perfect structure of synaptic vesicles as an indirect argument for neuronal plasticity
E. Grandi, D. Paci (eds.), La politica degli esperti. Tecnici e tecnocrati in età contemporanea
No full textR. Ventresca, recensione a: E. Grandi, D. Paci (a cura di), La politica degli esperti. Tecnici e tecnocrati in età contemporanea, Milano, Unicopli, 201
Struttura ed aspetti stagionali della cistifellea di alcuni pipistrelli
No full textThe gallbladder of the insectivorous hibernating bats (Pipistrellus pipistrellus et Rhinolophus ferrumequinum) in fullness, shows a fundus, a corpus and a neck. Its wall is formed by three layers: mucous membrane, with simple columnar epithelium on a thin basal lamina, beneath which is a "lamina propria" of connective tissue with blood and lymphatic vessels; lamina muscularis, constituted by three of four parallel bundles of smooth muscle cells, arranged in circular pattern; serous membrane of loose connective tissue, with precollecting lymphatic vessels and covered by mesothelial cells. By SEM the luminal surface of mucous membrane shows more or less prominent folds delimiting irregular areas with hexa-pentagonal outlines of the apical region of epithelial cells. This latter present a convex dome aspect with numerous microvilli, not changed significantly, during the different year periods. In summer and autumn the epithelial cells are characterized by developed organelles in supranuclear cytoplasm. During the prehibernating period, chiefly the cytoplasm shows multivesicular and heterogeneous dense bodies. In summer, autumn and initial hibernating period, epithelial cell cytoplasm presents microvilli with prominent "antennulae microvilares", numerous light micropinocytosis vesicles, little rough vesicles in apical portion. The mitochondria, grouping in supranuclear and basal cytoplasm, in lethargy, are characterized by small matrix osmiophilic granules. The epithelial cells are held together near the apical surface by tight and gap junctions, and some rare desmosomes only in Rhinolophus f.e. The cell membranes are deep pleated or interdigitate with wide intercellular spaces during the prehibernating period and experimental arousing, while in lethargy and summer months these present linear outline with scanty invaginations. The Authors compared these morphological aspects of bat gallbladder with other micromammalia's one, underline particularly the functional role of dense bodies, wide intercellular spaces and apical micropinocytosis vesicles. The different seasonal ultrastructural characteristics of epithelial cells are considered in close relation to an absorbing function connecting with balance of different metabolisms
Well-posedness of an isothermal diffusive model for binary mixtures of incompressible fluids
No full textWe consider a model describing the behaviour of a mixture of two incompressible fluids with the same density under isothermal conditions. The model consists of three balance equations: a continuity equation, a Navier-Stokes equation for the mean velocity of the mixture and a diffusion equation (Cahn-Hilliard equation). We assume that the chemical potential depends on the velocity of the mixture in such a way that an increase in the velocity improves the miscibility of the mixture. We examine the thermodynamic consistence of the model which leads to the introduction of an additional constitutive force in the motion equation. Then, we prove the existence and uniqueness of the solution of the resulting differential problem
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A thermodynamic approach to isotropic-nematic phase transitions in liquid crystals
No full textWe propose a dynamical model for (non-isothermal) phase transitions in liquid crystals. Macroscopic motions of the liquid crystal (LC) are neglected, while the coupling with the electromagnetic field is considered. The LC is described in terms of the classical order tensor Q, which is split as Q=s N, where N is a normalized tensor; two independent evolution laws are given for s and N. The model includes an evolutive equation for the temperature field obtained from an appropriate form of the energy balance, in which the internal powers associated to the equations for s and N are accounted for. The thermodynamic restrictions in the constitutive relations which ensure the Clausius-Duhem inequality have been pointed out
The peripheral absorbing lymphatic vessels of the diaphragm
No full textThe aim of our study was to examine the lymphatic vascularization of the diaphragm in hibernating bats (Pipistrellus pipistrellus, Rhinolophus ferrumequinum) and the ultrastructural characteristics of the absorbing peripheral lymphatic vessels of the pleural and peritoneal surface, and also to determine how far and with which mechanisms these vessels participate in the mobilization of liquids and particles (China ink and polystyrene latex sferules) from the abdominal cavity. Deep lymphatic vessels forming networks and superficial lymphatic vessels were observed draining at the diaphragm's peripheral margin into valved pre-lymph node precollectors and collectors; the ventral precollectors principally terminate into the sternal lymph nodes or into the anterior mediastinal lymph nodes, while the dorsal precollectors terminate into the interrenal or para-aortic lymph nodes. The superficial lymphatic vessel undergoes significant seasonal changes, and as in other organs, has peculiar absorbing properties characterized by the membrane diffusioon phenomena, the 'vesicular pathway', and the 'intraendothelial channel pathway'. We demonstrated and discussed the ultrastructural aspects of the mesothelial stoma and the lower mesothelial connective channel, which are important components of the drainage unit. The peritoneal or abdominal contents drain indiscriminately first into the lymphatic vessel lumen and then into the valved precollectors by means of the intraendothelial channel, a dynamic entity organized by and according to the requirements of the endothelial wall. The valves block back flow during the rhythmic contractions of the diaphragm. Three-dimensional models and serialized thin slices of the lymphatic vessels and drainage unit components, have not confirmed the 'lymphatic stomata' hypothesis or direct continuity between the abdominal cavity and the lumen of the lymphatic vessels
Struttura ed immunoistochimica dell'ipofisi di Alosa fallax nilotica durante il ciclo migratorio per la riproduzione
No full textThe Pituitary of the Alosa fallax nilotica consists of a pars distalis, a pars intermedia and a pars nervosa. The pars distalis is divided into rostral and proximal. The pars nervosa extends also into proximal pars distalis. The rostral pars distalis, on the contrary in primitive Teleostei, has organized into cellular cords defining cavities or intercommunicating follicles. These latter finish into the oral adenohypophysial duct, which don't open in pharyngeal cavity. The cords contain three cell types: the columnar cells LTH, TSH cells and basal cells not yet functionally determined. The cord cells are separated from follicle cavity by an one layer of flat degranulated cells. The LTH cell, the chief cell type, together the TSH and basal cells shows evident cytologic differences in organelles of synthesis and secretion during the various stages of the reproductive migration. Besides globular and baton-shape projections are underlined in the apical cytoplasm of LTH cells. These structure, extending into follicle cavity, seem to dispatch sensory function probably. The proximal pars distalis consists of compact cords of gonadotropic cells (particularly active during the stage of migration from rivers to the sea) with inserted orangiophilic cells (probably STH) and phloxine cells: these latter cells are chiefly arranged at the periphery and immunocytochemical positive for the antibodies against ACTH. The pars intermedia contains cord of ACTH cells, particularly manifest during the periods of transit from sea water to fresh water and on the contrary, they are characterized by positive-ACTH dense granules. On the ground of ultrastructural aspects of vesicles, the pars nervosa shows three types of nervous fibers which correlate with neurosecretory hypothalamus and catecholaminergic dopaminergic fibers. The Authors think of underlining particularly that the all cells of rostral pars distalis and chiefly the LTH cells are involved significantly in the regulation of reproduction and hydro-mineral metabolic equilibrium
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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