1,720,971 research outputs found
Espressione in cellule umane del gene della glicoproteina B del virus dell'herpes simplex inserito in un vettore eucariotico
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Abitudini e conoscenze sul fumo in un campione di giovani di scuola media inferiore del delta del Po
No full textIndagine finalizzata a valutare la prevalenza dell’abitudine al fumo tra gli adolescenti che frequentano la scuola media inferiore in una zona del ferrarese ad elevata mortalità per tumore polmonare. Nel periodo febbraio-giugno 2004 è stato somministrato un questionario anonimo a 172 studenti di scuola media inferiore (84 maschi e 88 femmine) di 3 scuole della bassa ferrarese allo scopo di valutare, a seguito delle numerose campagne antifumo ministeriali e sui mass-media, sia le conoscenze che le attuali abitudini dei giovani nei confronti di questo problema.
Nella fascia di età tra gli 11 e 15 anni (età media 12,5 anni), il 64% dei ragazzi non ha mai fatto uso di sigarette. Quasi la metà degli intervistati ha iniziato a fumare prima dei 12 anni (49%) e comunque il 98% ha cominciato a fumare prima dei 14 anni. Addirittura il 70% dei maschi ha iniziato a fumare prima dei 12 anni, contro il 25% delle femmine. Il 36% dei ragazzi si è avvicinato per la prima volta al fumo perché lo facevano gli amici che frequentavano ed il 59% per curiosità per provare emozioni nuove. Il 36% ha dichiarato di fumare al momento della rilevazione da 6 a 10 sigarette al giorno, il 28% ne fuma da 1 a 5.
La maggioranza (59%) ha tentato almeno una volta senza successo ed il 18% non ha mai provato a smettere di fumare.
Nelle famiglie di studenti che fumano il 70% dei familiari fa uso di sigarette, mentre solo il 31% dei componenti familiari di studenti non fumatori al momento dell’indagine fuma. Solo il 26% però fuma liberamente in presenza dei familiari, mentre il 74% fuma di nascosto senza il permesso dei genitori.
La maggioranza degli studenti (87%) è consapevole che il fumo è molto dannoso alla salute, solo il 6% è convinto che non lo sia per nulla o comunque molto meno di quanto venga fatto credere. Quindi malgrado la diffusione delle informazioni sulle conseguenze nocive del fumo per la salute, il ricorso soprattutto al fumo di sigaretta è sempre più presente tra i giovani. I risultati di questa indagine suggeriscono la necessità di non abbassare la guardia nei confronti del fumo tra gli adolescenti e di continuare con campagne educative che tengano in forte considerazione l’ambiente socioeconomico in cui i giovani vivono.
The present study, conducted from February ti June 2004, was carried out by means of a questionnaire distribuited to 172 middle-school students in some towns of the Po Delta. The questionnaire aimed to asses the knowledge and attitudes about smoking among 11-15 year old students. The data analysis lead us to the followuing conclusions: ---
The results of this study suggest the need for more frequent anti-smoking campaigns targetting yong people, taking into consideration the influence of their social environment
Growth response of sphagnum capillifolium to nighttime temperature and nutrient level: Mechanisms and implications for global change
No full textIndividuals of Sphagnum capillifolium were cultured for 2 mo under six different combinations of nighttime temperature and nutrients. Low nighttime temperature caused a five-fold reduction of growth. Growth was also reduced when the plants were cultured without any addition of nutrient in the growing medium, but only when nutrient deficiency was coupled with high nighttime temperature. Growth reduction was associated with decreased rates of net photosynthesis, but was not accompanied by a degradation of photosynthetic pigments and/or variations in the pigment ratios, nor was the ultrastructure of chloroplasts significantly altered. The decline in the net photosynthetic rate may be due to a limitation in the enzymatic reactions at unfavorable temperatures. Nitrogen and, especially, phosphorus appeared to limit growth of Sphagnum capillifolium at optimal temperatures. A nighttime temperature of 5°C was above the lower threshold triggering the synthesis of red wall-pigments, known to be promoted by nighttime chilling. Climate warming is expected to increase the growth rates of Sphagnum, but the consequences on the carbon balance of peatlands cannot be predicted because temperature rise may also enhance breakdown of peat
Carotenoid and ultrastructure variations in plastids of Arum italicum miller fruit during maturation and ripening
No full textThe changes in the pigment pattern and composition occurring in the Arum italicum berry during the various steps of maturation (ivory to deep-green stages) and ripening (yellow and red-orange stages) were studied and correlated to the ultrastructural modifications of plastids. Transmission electron microscopy showed that each stage was characterized by a specific plastidial type following the unusual sequence amyloplastchloroplastchromoplast. Plastidial transitions were accompanied by profound modifications in the pigmental composition, in particular, in the pattern of carotenoids and their precursors. The HPLC analysis of the carotenoids showed that, besides the two usual all-trans metabolic pathways leading to lutein through alfa-carotene and to auroxanthin through ß-carotene, an additional cis-isomeric biosynthetic pathway leading to cis-neoxanthin through cis-ß-carotene exists. During the pre-ripening stages, the three pathways were present even if with qualitative and quantitative variations. When complete ripening was reached, a block occurred at the cyclization level causing the accumulation of both all-trans (i.e. gamma-carotene and neurosporene) and cis-isomer (i.e. lycopene and zeta-carotene) carotene precursors. Because of the occurrence of unusual pigments and the presence of the three main plastidial types, the fruit of A. italicum may constitute a most instructive model for the study of carotenogenesis
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
CO<sub>2</sub> exchange, photosynthetic pigment composition, and cell ultrastructure of <i>Sphagnum</i> mosses during dehydration and subsequent rehydration
No full text Sphagnum mosses of three different species (S. capillifolium, S. magellanicum, and S. fallax) were allowed to dry in a controlled environment. The three species lost water at different rates, but after 11 days of exposure to drying atmosphere all were dry and unable to photosynthesize. The chlorophyllose cells of all three species showed signs of alteration, mainly membrane shrinkage. Upon rehydration, concentrations of photosynthetic pigments (chlorophyll a to a greater extent than chlorophyll b) declined in tissues of S. magellanicum and especially in S. fallax. Sphagnum capillifolium and S. magellanicum resumed photosynthesis, although slowly, whereas S. fallax did not achieve a net carbon gain (most of its chlorophyllose cells were irreversibly damaged) after 7 days of rewetting. In the field, prolonged drought may alter the interspecific equilibria among coexisting Sphagnum species possessing different degrees of desiccation-tolerance and especially different water-holding abilities. Keywords: Sphagnum, photosynthesis, ultrastructure, photosynthetic pigments, dehydration, rehydration. </jats:p
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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