146 research outputs found
Valutazione del ciclo nasale di dieci giovani soggetti: indagine rinomanometrica
No full textObiettivi. Valutare tramite rinomanometria il ciclo nasale di giovani bambini ed evidenziare le caratteristiche e le implicazioni ortognatodontiche. Materiali e metodi. Sono stati analizzati dieci giovani soggetti con il rinomanometro Markos NR 4 che rileva la pressione dell’aria che scorre nelle cavità nasali e il flusso aereo. Si sono effettuate dieci registrazioni in cinque ore, a intervalli regolari di 30 minuti. Ogni registrazione è stata eseguita a tre valori di flusso costante equivalenti a 50, 100, 150cm3 /sec e alla pressione costante di 100 Pascal. Risultati. Le resistenze delle due narici si sono rilevate inversamente proporzionali, con andamento ricorrente nel tempo. Il tempo che intercorre tra due fasi omologhe non è stato chiarito. Si è riscontrata una grande variabilità interindividuale e intraindividuale nel tempo. Conclusioni e implicazioni cliniche. La valutazione rinomanometrica si è rivelata una indagine non invasiva e molto utile in fase diagnostica e terapeutica ortognatodontica. Inoltre, essa risulta spesso alterata a causa di discrepanze del diametro trasverso del mascellare superiore.bjectives. To evaluate the nasal cycle in young children by rhinomanometry and to point out its characteristics and orthodontic implications. Materials and methods. Air pressure and air flow in nasal cavities of 10 young patients have been analyzed by a Markos NR 4 equipment. Ten registrations in five hours were performed with an interval of 30minutes. Every registration was performed with three values of constant flux at 50,100,150cm3/sec and a pressure of 100 Pascal. Results. The resistance of nasal cavities was inversely proportional showing a recurrent trend through time. Time between two similar phases was not measured. A large interindividual and intraindividual variation was recorded. Conclusions. Rhinomanometric evaluation revealed to be a non invasive analysis very useful both for diagnosis and treatment. It is also often altered by transverse maxillary hypoplasia
A facile preparation of 2(Z),5(Z),8(Z)-tetradecatrien-1-ol, a key intermediate for eicosanoid synthesis
No full textDiisobutylaluminum hydride reduction of unsaturated silylcyanohydrins: a new entry to confertifolin
No full textA new entry to the drimane-related sesquiterpene Confertifolin is reported. The key step involves the conversion of a β-phenylthio-α,β-unsaturated ketone into the corresponding silylcyanohydrin followed by diisobutylaluminum hydride reduction to the homologous α,β-unsaturated aldehyde
Gli effetti del factoring sulle imprese italiane: alcune evidenze empiriche.
No full textThe empirical literature about factoring mainly focuses on the reasons why firms use factoring, suggesting the role of many factors such as the age of the firm, the size, the financial structure and the features of the product, of the distribution channels and of the trade relationships, without analyzing the potential effects that the use of factoring may generate on the firm both on the management and the financial structure. This work focus on two level of analysis: a qualitative survey about the insight of the firms with regard to the effect of factoring, that takes into account the answers given by the firms during a previous research, and a quantitative analysis of their balance sheets. This analysis provides interesting results which confirm some of the theories about the effect of the use of factoring on the firms: firms using factoring in a wide, systematic and long-lasting relationship are more able to identify well the benefits on the trade credit relationship and to correctly evaluate the suitability of factoring in respect to those who use it in a occasional or limited fashion. Moreover, results confirm also some of the theoretical previsions about the effect of a "correct" use of factoring on the balance sheet of the firm in terms of profitability, financial structure and, at the end of the day, a better overall performance
2-OXAZOLIDINONES AS REGIOSELECTIVE PROTECTION OF BETA-AMINO ALCOHOLS IN THE SYNTHESIS OF 2-AMINO-1-ARYL-3-FLUORO-1-PROPANOLS
No full textIndividual capture histories of breeding Cory's shearwaters at Pantaleu islet, with information on wintering areas
No full text[Description of methods used for collection/generation of data] Individual capture histories were built from long-term individual capture-recapture monitoring of adult Scopoli’s shearwater Calonectris diomedea breeding in Pantaleu islet. Some of these individuals were also equipped with geolocators, that when recovered, may provide information of wintering movements and individual wintering areas. All the information about the deployment of geolocators devices and wintering areas visited are encoded in the individual capture histories. The file includes 23 annual encounter occasions, which translate into 45 coded encounter occasions, with the ‘inter’ encounter occasions encoding information about presence in the colony and migratory decisions, and the ‘intra’ occasions encoding information about whether a geolocator had been deployed or not at the end of the season.Long-term individual capture-recapture monitoring of adult Scopoli’s shearwater Calonectris diomedea breeding in Pantaleu islet has been carried out by: M Genovart, JM Igual, A Sanz-Aguilar, G Tavecchia, A Rotger & D Oro. Information from geolocators on wintering movement and wintering areas were analysed by R Ramos, T Militão, D Vicente-Sastre, B Garcia-Urdangarin & J González-Solís.Este fichero contiene información de las historias de captura individuales de Pardela cenicienta criando en el islote de Pantaleu, Mallorca, durante el período 2000-2022. En estas historias de captura anuales se ha incluido información de la colocación de dispositivos geolocalizadores en algunos de estos individuos, y la información que se obtuvo de las zonas de invernada visitadas por estos individuos.Peer reviewe
Density-dependent parameters and demographic equilibrium in open populations
No full textInternational audienceG. Tavecchia ([email protected]), R. Pradel, M. Genovart and D. Oro, IMEDEA (UIB-CSIC), 21 M. Marques, ES-07190 Esporles, Spain. Populations near their equilibrium are expected to show density-dependence through a negative feedback on at least one demographic parameter, e.g. survival and/or productivity. Nevertheless, it is not always clear which vital rate is affected the most, and even less whether this dependence holds in open populations in which immigration and emigration are also important. We assessed the relative importance of population density in the variation of local survival, recruitment, proportion of transients (emigrants) and productivity through the analysis of detailed life-histories of 4286 seabirds from a colony that reached an apparent demographic equilibrium after a period of exponential increase. We provide evidence that the role of population density and resource availability changes according to the demographic parameter considered. Estimates indicated that transients increased from 5% to 20% over the study period, suggesting an average turnover of about 1400 individuals per year. The parameters most influenced by population density alone were local survival and probability of transience. Recruitment was negatively associated with population density during the increasing phase but unexpected high values were also recorded at high population levels. These high values were explained by a combination of population size and food availability. Mean productivity varied with food availability, independently from population variations. The population density alone explained up to a third of the yearly variation of the vital rates considered, suggesting that open populations are equally influenced by stochastic and density-independent events (such as environmental perturbations) than by intrinsic (i.e. density-dependent) factors
Habitat- and density-dependent demography of a colonial raptor in Mediterranean agro-ecosystems
No full textAgricultural intensification is considered the major cause of decline in farmland bird populations, especially in the Mediterranean region. Food shortage increased by the interaction between agricultural intensification and density-dependent mechanisms could influence the population dynamics of colonial birds.Weused demographic data on lesser kestrels (Falco naumanni), a key species of Mediterranean pseudo-steppes, to understand the importance of land-use changes and density-dependent mechanisms in the light of its fluctuating conservation status in the Western Palearctic. Our analysis indicated an important influence of land uses (artichokes, arable and grassland fields) and colony size on kestrel survival rates. The strong habitat effect revealed the unsuitability of intensive arable lands with respect to extensive grasslands for lesser kestrels. Notably, artichokes, a winterintensive crop, proved to be a high-quality habitat as they were associated with survival values equal to those of grassland. This is likely due to prey availability and reveals that non-traditional crops may provide suitable habitats for lesser kestrels. Information theory gave strong support to the negative influence of colony size on fecundity, albeit a small one, for its positive effect on survival probability. The estimated population growth rate was negative for all three habitats, indicating a decline over time and urging conservation actions in all of the areas studied. This decline was much higher in colonies surrounded by arable fields. In sensitivity analyses, ? indicated that adult survivalwas the parameterwith the greatest effect on population growth, followed by survival of fledglings and fecundity. Our study showed howthe costs and benefits of group living interact with agricultural intensification to drive species demography. In addition, we integrated significant information on one of the largest lesser kestrel populations to fine tune the most effective conservation strategy to prevent the collapse of the species in a relevant part of its range.Funding was provided by the Italian Ministry of Education, University and Research (PRIN 2010-2011, 20108 TZKHC)Peer Reviewe
Estimating the functional form for the density dependence from life history data
No full textTwo contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified; and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and individual-level processes to the dynamics of populations in stochastic environments.<br/
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