Showing papers by "University of Bologna published in 1977"

Brightness as an Indicator to Distance: Relative Brightness per Se or Contrast with the Background?

Abstract: A black and a white target are displayed, in five different conditions, on five grey backgrounds having different degrees of brightness (from very bright to very dark). The results show that the target having the higher contrast with its background is perceived as the nearer. With the off-white background, e.g., the black target appears as the nearer to the observer. This contradicts the well-known concept according to which the brighter target should in any case be perceived as the nearer (‘relative brightness’ cue). The conclusion is that the frame of reference must be taken into consideration: study of the indicators to distance in an empty space and per se is not sufficient.

An ab initio investigation into the SN2 reaction: Frontside attack versus backside attack in the reaction of F− with CH3F

Abstract: The energy hypersurface for the attack of fluoride ion on methyl fluoride has been explored with ab initio LCAO-SCF calculations at a split-valence basis set level. Transition states for frontside and backside attack have been located. In addition to transition states, two possible F−-CH3F clusters have been identified. The transition state for the substitution of fluoride with retention of configuration is found to be 56 kcal/mol higher than the transition state for inversion of configuration. The transition state for hydride displacement with inversion is 62 kcal/mol above the transition state for fluoride substitution with inversion.

Blue naevi of lymph node capsule.

Abstract: Blue naevi are reported for what is believed to be the first time in the capsule and fibrous trabeculae of lymph nodes. In one of the two cases that nodal blue naevus was accompanied by an ordinary blue naevus in the regional skin. These blue naevi are compared with the 'naevus-cell aggregates' in nodal capsule, the histogenesis of which is currently disputed. A developmental migratory arrest of melanocytes is thought to be the histogenetic mechanism involved in the production of these blue naevi in lymph nodes.

Propagation in graded-core fibres: a unified numerical description

Abstract: The well-known stepped-index representation for graded-core fibre analysis is extended to cover all aspects of fibre propagation on a rigorous electromagnetic basis. Calculations are implemented on a large digital computer system, and a new, very efficient formulation is used, so that the resulting program package turns out to be a very general and powerful tool for fibre description. It can be used to establish on a quantitative basis the merits and limitations of well-known approximate procedures (e.g., the WKBJ method) and, at the same time, to get considerably deeper insight into the exact mode pattern of the graded-core fibre than provided by existing approximations.

Morpho-functional differentiation in lobular carcinoma of the breast.

Abstract: Lobular carcinoma of the breast has been studied using histochemical methods for mucosubstances; immunocytochemical methods for casein and actin; the ruthenium red electronycytochemical method for acid glycoproteins and an immunoelectroncytochemical method for casein. Mucosubstances and casein showed a similar cytoplasmic localization, but casein production was much more intense and also showed a more diffuse cytoplasmic localization. Occasionally casein assumed the form of target-like 'inclusions' as seen characteristically with the mucosubstances. The neoplastic cells were not stained by antisera against actin. Ultrastructurally, some cells showed an intracytoplasmic lumen with microvilli and/or an irregular outline at one extremity which was covered by microvilli. An electron-dense 'fuzz' and casein coated the microvilli of cells exposed respectively to ruthenium red and an anticasein serum followed by peroxidase--anti-peroxidase complexes. It is concluded that lobular carcinoma shows evidence of epithelial rather than myoepithelial differentiation with the emphasis on epithelial secretory cells engaged in intensive milk protein production. All 10 tumours tested for oestrogen receptors were positive in contradistinction to ductal carcinoma with a lower incidence of positivity. It appears that, in addition to distinctive histological and histochemical features, lobular carcinoma has an almost constant endocrine pattern in respect of its oestrogen receptor content.

Inertial and frictional effects on rotating and stratified flow over topography

Abstract: The separate effects of fluid inertia and friction at the lower boundary on the flow of a rotating, stably stratified, incompressible fluid over a three-dimensional shallow isolated obstacle are investigated. Analytic solutions of the perturbation equations are obtained as a power series expansion in the Rossby number, and some examples are presented. Possible meteorological applications to the flow over the Alps are discussed.

530 nm-Laser Photolysis Studies of the Photo Reduction of Tris (2,2-bipyridine)-ruthenium(II) by Organic Donors

Abstract: The reduction of the excited charge-transfer state of tris(2,2'-bipyridine)-ruthenium(II), Ru(bipy)32+ by organic donors (D) in methanol was studied by laser photolysis technique. The reduction follows the general schema: The rate of reduction is diffusion controlled for all donors except diphenylamine for which a rate constant of 2.5 · 107 M−1 s−1 was obtained. The reduction potential of *Ru(bipy)32+ was determined experimentally to lie close to the thermodynamic limit of 0.85 V. - Reaction (1) and subsequent dark reactions were examined in detail for D = phenothiazine (PTH). For this donor the efficiency of electron transfer was found to be 0.6 ± 0.2. The spectrum of Ru(bipy)3+ obtained from these studies shows a maximum at λ = 510 nm with an extinction coefficient of 1.8 · 104 M−1 cm−1. Ru(bipy)3+ was found to decay exponentially with a time constant of 1.1 · 105 s−1. At higher PTH concentrations, this reaction competes with electron transfer from Ru(bipy)3+ to PTH for which a rate constant of 3.4 · 107 M−1 s−1 was obtained. Die Reduktion des angeregten charge-transfer-Zustandes von Tris(2,2′-bipyridine)-ruthenium(II), Ru(bipy)3 durch organische Donormolekule wurde in methanolischer Losung mit Hilfe der Laserphotolyse untersucht. Die Reduktion folgt dem Schema: Die Reduktionsgeschwindigkeit ist diffusionskontrolliert fur alle Donoren, ausgenommen Diphenylamin, fur welches eine Geschwindigkeitskonstante von 2,5 · 107 M−1 s−1 erhalten wurde. Das experimentell bestimmte Reduktionspotential von *Ru(bipy)32+ ist fast identisch mit dem thermodynamischen Grenzwert von +0.85 V. - Fur das System D = Phenothiazin wurde eine detaillierte Analyse von Reaktion (1) sowie nachfolgenden Dunkelreaktionen der Produktionen durchgefuhrt. Fur diesen Donor betragt die Effizienz von Reaktion (1) 0.6 ± 0.2. Das Absorptionsspektrum von Ru(bipy)3+ wurde bestimmt. Es zeigt ein Maximum bei λ = 510 nm mit einem Extinktionskoeffizienten von 1.8 · 104 M−1 cm−1. Ru(bipy)3+ verschwindet nach exponentiellem Zeitgesetz mit einer Zeitkonstanten von 1.1 · 105 s−1. Bei hoherer Phenothiazinkonzentration kompetiert diese Abreaktion mit Elektronentransfer von Ru(bipy)3+ zu Phenothiazin, wofur eine Geschwindigkeitskonstante k = 3.4 · 107 M−1 s−1 erhalten wurde.

The behavior of 9-aminoacridine as an indicator of transmembrane pH difference in liposomes of natural bacterial phospholipids.

Abstract: The behavior of 9-aminoacridine as an indicator of pH differences artificially set across a membrane has been reexamined in liposomes prepared from bacterial phospholipids extracted from chromatophores ofRhodopseudomonas capsulata grown photoheterotrophically. The dye behaves as an ideal indicator for pH differences lower than about three units; at higher pH's the expected linear dependence of Q/(100-Q) vs. pH is no longer strictly observed. Similarly a linear dependence upon the volume of the liposomes added has been verified. The amine ceases to respond to pH changes when the pH of the external medium exceeds the value of 10, corresponding to the pKa of 9-aminoacridine. The apparent volume of the inner phase of liposomes, as calculated from fluorescence quenching, but not the slope of dependence of fluorescence on pH, appears to be affected by several factors, including the ionic composition, the osmolarity of the external medium, and the microscopic structure of the liposomes. Millimolar concentrations of earth-alkaline cations diminish the apparent internal volume of liposomes, in agreement with the complexing effect of these ions on phospholipid bilayers. The osmotic response of the apparent inner volume has also been verified; this parameter decreases linearly with the reciprocal of the external osmolarity, as expected from the van't Hoff relation; an osmolarity exceeding 0.3 M is, however, necessary in order to observe this effect.

Chemical and physical methods in dating human skeletal remains.

Abstract: Chemical and physical methods for dating skeletal remains were examined. Benzidine reaction, ultra-violet fluorescence, specific gravity and supersonic conductivity were carried out on 71 dated skeletal findings distributed over the span of the last 3,500 years. Results given by benzidine reaction and ultra-violet fluorescence basically coincide, and positive readings were obtained up to about 200–350 years. Values measured in specific gravity and supersonic conductivity testing show a parallel trend, pointing out a clear difference between samples of the three first centuries and the ones belonging to more ancient periods examined.

Calorimetric investigation of some elastin‐solvent systems

Abstract: The interaction of ox ligamentum nuchae elastin (native, purified, and soluble) with different solvents (water, ethylene glycol, methanol, and 2,2,2-trifluoroethanol) was investigated by means of differential scanning calorimetry. The unfreezable solvent content and the corresponding solvent to elastin residue molar ratio were determined from the melting endotherms of the freezable solvent present in these systems. The molar ratio obtained in the case of water and ethylene glycol agrees with hypothesis of a direct solvation of the main chain peptide group and is interpreted according to a model previously proposed for polyamides. Quite different molar ratios are obtained in the case of the two monofunctional solvents and no model can be proposed at present to explain their interaction with the protein.

Acute promyelocytic leukemia: results of therapy and analysis of 13 cases.

Abstract: Acute promyelocytic leukemia (APL) was diagnosed in 13 of 84 adult patients (15.4%) with acute myeloid leukemia (AML) first admitted between 1972 and 1976. All patients had clinical and/or laboratory

Photosensitized reactions in an annular continuous photoreactor

Abstract: The process of energy emission by a lamp of finite spatial dimensions is considered, and a general expression for the local volumetric rate of energy absorption (L.V.R.E.A.) is given under the assumptions of no reflection and of negligible scattering and emission phenomena in the absorbing medium. When a reaction is occurring in the absorbing medium, L.V.R.E.A. can be easily computed if the reaction is a photosensitized one. In this case profiles of L.V.R.E.A., computed in an annular photoreactor solving the equations which govern rigorously the phenomenon, can differ in a relevant way from those computed assuming a radial model for the emission by the same lamp, the difference being mainly dependent, for a given radial geometry, on the reactor length and on the value of the optical thickness of the absorbing medium. Photosensitized reactions of order 0 and 1 with respect to the reactant concentration were studied for different values of the optical thickness, of Damkoheler and Peclet numbers. In particular the effects of variations of Pe number on the conversion were taken into consideration and the results were explained on the basis of physical and mathematical arguments.

Epileptic Seizures Precipitated by Eating

Abstract: SUMMARY The case of a mentally retarded 18-year-old girl who for 2 years has experienced epileptic seizures exclusively during meals is discussed. Polygraphic recordings have defined the electrical and clinical features of these seizures. None of the possible precipitating factors considered in other cases in the literature (chewing, swallowing, conditioned reflex, etc.) seems to be involved in this case. We hypothesize that in our patient the precipitating factor is the complete act of eating a meal, which involves the satisfaction of a basic drive. RESUME On presente une frlle de 18 ans, retardee mentale, ayant eu pendant deux ans des crises dpileptiques exclusivement pendant les repas. Les enregistrements polygraphiques ont defini les aspects electriques et cliniques des crises. Les facteurs declanchants deja decrits en literature (marcher, avaler, reflex con-ditionne, etc.) ne semblaient pas pouvoir expliquer le cas en question. On pense que le facteur provocateur etait Facte de manger dans sa globalite qui met en jeu la satisfaction d'une necessite instinctive. RESUMEN Se discute el caso de una enferma de 18 anos, re-trasada mental, que ha experimentado, durante dos anos, ataques convulsivos exclusivamente durante las comidas. Registros poligraficos definen las caracteris-ticas elceAtricas y clinicas de los ataques. Ninguno de los posibles factores precipitantes considerados en otros casos de la literatura (masticacien, deglucien, reflejos condicionados, etc.) han participado en este caso. Se presenta la hipetesis de que, en nuestra paciente, el factor precipitante es el acto complete de comer que incluye la satisfaccien de un impulso basico. ZUSAMMENFASSUNG Diskussion der Krankengeschichte eines geistig re-tardierten 18-jahrigen Madchens, das wahrend 2er Jahre epileptische Krampfe ausschliebZlich wahrend der Mahlzeiten bekommen hat. Polygraphische Ab-leitungen lassen die elektrischen und klinischen Be-sonderheiten dieser Krampfe abgrenzen. In diesem Fall scheint keiner der moglichen auslosenden Fakto-ren, wie sie in anderen Fallen der Literatur bes-chrieben wurden (Kauen, Schlucken, bedingter Reflex usw.) eine Rolle zu spielen. Die Autoren vermuten, das in diesem Fall der auslosende Faktor der gesamte EBakt darstellt der auch die Befriedigung eines Grundbedurfnisses darstellt.

Mitochondrial and cytoplasmic ribosomes from mammalian tissues. Further characterization of ribosomal subunits and validity of buoyant-density methods for determination of the chemical composition and partial specific volume of ribonucleoprotein particles

Abstract: 1. At 0–4°C mitochondrial ribosomes (55S) dissociate into 39S and 29S subunits after exposure to 300mm-K+ in the presence of 3.0mm-Mg2+. When these subunits are placed in a medium containing a lower concentration of K+ ions (25mm), approx. 75% of the subparticles recombine giving 55S monomers. 2. After negative staining the large subunits (20.3nm width) usually show a roundish profile, whereas the small subunits (12nm width) show an elongated, often bipartite, profile. The dimensions of the 55S ribosomes are 25.5nm×20.0nm×21.0nm, indicating a volume ratio of mitochondrial to cytosol ribosomes of 1:1.5. 3. The 39S and 29S subunits obtained in high-salt media at 0–4°C have a buoyant density of 1.45g/cm3; from the rRNA content calculated from buoyant density and from the rRNA molecular weights it is confirmed that the two subparticles have weights of 2.0×106 daltons and 1.20×106 daltons; the weights of the two subunits of cytosol ribosomes are 2.67×106 and 1.30×106 daltons. 4. The validity of the isodensity-equilibrium-centrifugation methods used to calculate the chemical composition of ribosomes was reinvestigated; it is confirmed that (a) reaction of ribosomal subunits with 6.0% (v/v) formaldehyde at 0°C is sufficient to fix the particles, so that they remain essentially stable after exposure to dodecyl sulphate or centrifugation in CsCl, and (b) the partial specific volume of ribosomal subunits is a simple additive function of the partial specific volumes of RNA and protein. The RNA content is linearly related to buoyant density by the equation RNA (% by wt.)=349.5−(471.2×1/ρCsCl), where 1/ρCsCl=[unk]RNP (partial specific volume of ribonucleoprotein). 5. The nucleotide compositions of the two subunit rRNA species of mitochondrial ribosomes from rodents (42% and 43% G+C) are distinctly different from those of cytoplasmic ribosomes.