1,721,196 research outputs found
Note di ricerca sugli insediamenti e sugli edifici di culto nel periodo medievale
Full text linkIl periodo che va dalla caduta dell'impero romano d'occidente all'anno Mille, per la carenza delle fonti letterarie e per la discontinuità delle testimonianze materiali, rimane uno dei più oscuri della nostra storia. Se le ricerche archeologiche attuate negli ultimi decenni
hanno permesso di individuare un numero sempre maggiore di siti e di strutture tardo antichi e alto medioevali permettendo di mettere in luce particolari aspetti di quelle culture, per il territorio di Sedilo mancano, invece, uguali testimonianze atte a suffragare eventuali ricostruzioni storico-topografiche.In particolare, per il periodo bizantino, le fonti sono talmente scarse che la sua ricostruzione è stata spesso vista e puntualizzata alla luce dell'organizzazione degli altri domini imperiali con un margine d'incertezza dato dal particolare contesto storico-sociale dell'isola.
Un dato di significativo interesse per i secoli VI-VIII d. C. è costituito dalla vicinanza al centro militare di Fordongianus che fu certamente di grande importanza per lo sviluppo economico e per l'assetto territoriale della media valle del Tirso
Photostability and solubility improvement of beta-cyclodextrin-included tretinoin
No full textIn this work, we investigated the influence of bcyclodextrin
on the photostability of tretinoin and compared
the photo-chemical stability of tretinoin, either in
methanol or complexed with b-cyclodextrin, when exposed
both to UV and fluorescent light. The physico-chemical
characterization of tretinoin-b-cyclodextrin complexes,
prepared by the freeze-drying process, using different
tretinoin:b-cyclodextrin molar ratios (1:1 and 1:3), was
carried out in solution by phase solubility studies, 1HNMR
spectroscopy, and in solid state by infrared spectroscopy
(FT-IR); these analyses confirmed the existence of
an inclusion compound. Solubility study results showed
that tretinoin solubility was enhanced by inclusion in
b-cyclodextrin as a function of increasing concentrations of
b-cyclodextrin in aqueous solution at different pH values
(i.e., 3.0, 5.5, and 7.0). Moreover, the complexation of the
tretinoin with b-cyclodextrin effectively protected the
photolabile drug and reduced the degradation of tretinoin
induced by UV and fluorescent light, improving its photochemical
stability in comparison with free drug in methanol.
Indeed, dissolved tretinoin in methanol degraded very
quickly and completely, while b-cyclodextrin-included
tretinoin decomposition was delayed and, after 30 days
under UV exposure, the percentage of remaining drug was
about 20–25% (depending on the tretinoin concentration).
The photodegradation of tretinoin in methanol under fluorescent
light was slower: after 5 days of irradiation it
reached a photostationary state and intact tretinoin remained
constant (6.6%). In conclusion, the b-cyclodextrin
complexation always led to a reduction of degradation,
depending on the tretinoin:b-cyclodextrin molar ratio and
on the drug concentration (0.2 mg/ml or 0.4 mg/
Aggregati vescicolari tridimensionali di fosfolipidi dispersi in miscele alcoliche a baso o nullo contenuto d'acqua, loro preparazione e loro uso in formulazioni per applicazione topica.
No full text
Seed germination requirements of Hypericum scruglii, an endangered medicinal plant species of Sardinia (Italy)
Full text linkHypericum scruglii is an endangered endemic plant of Sardinia and the phloroglucinol compounds identified in this species have been reported to inhibit Human Immunodeficiency Virus activity. Seed banks are a genetic repository that effectively preserve taxa of conservation interest and they hold knowledge about the biology and germination eco-physiology of the taxa they preserve. The main goals of this study were to investigate the germination requirements of H. scruglii, to evaluate the seed viability after eight years of long-term conservation and to suggest an efficient protocol for germination. Seeds stored at -25 °C in the seed bank were tested at temperatures from 5 to 30 °C and 25/10 °C. Base temperature (Tb) and thermal time (θ50) for germination were estimated. H. scruglii seeds germinated over a wide range of temperatures, responding positively to high temperatures and 25/10 °C. Tb was estimated at 4.92 °C, and θ50 was estimated at 198.27 degree days. The high viability detected in seeds of H. scruglii allows us to suggest the use of seeds stored in a seed bank when fresh material for plant propagation is scarce. Our results provide new and useful baseline information for implementing conservation and multiplication strategies for this endangered medicinal plant
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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