102,035 research outputs found
Diisobutylaluminum 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
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
Home-range and habitat use of long-eared owls in open farmland (Po Plain, Northern Italy) in relation to prey availability
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Woodpigeon nesting in association with hobby falcons: advantages and choice rules
No full textMany bird species nest in close association with other bolder and more aggressive birds which provide protection against nest predators. The woodpigeons, Columba palumbus, that nest in poplar plantations in Northern Italy are found almost exclusively clumped around hobby, Falco Subbuteo, nests. Woodpigeons settle in the area and build their nests after the hobby has started nesting. We carried out experiments with dummy nests and observations on woodpigeon nests. Dummy woodpigeon nests placed near a hobby's nest suffered less depredation by hooded crows, Corvus corone cornix, than those placed far from it. A logistic regression analysis showed that three variables, hobby nesting stage, distance from the hobby's nest and the hobby's aggressiveness, influenced the probability of nest predation. The degree of protection varied during the hobby's nesting period and was highest when chicks were in the nest. The hobby's aggressiveness against intruders varied both between and within individuals during different nesting phases. The predation rate of dummy nests associated with the falcon was negatively correlated with the aggressiveness score of the hobby during the 6 days of dummy nest exposure. Observations on real nests showed that woodpigeons selected hobbies that had a high fledging success, and a more vigorous defensive behaviour. Clues that would allow woodpigeons to choose the best protector may be early nesting by the hobby and its aggressiveness. Hobbies preyed on adult woodpigeons, but the risk incurred by the woodpigeons was low compared with the very high risk of nest predation in this area
Parental defence in Long-eared Owls Asio otus: effects of breeding stage, parent sex and human persecution.
No full textThe responses of male and female Long-eared Owls to a human approaching the nest were examined. Each nest was only tested once. Nest defence increased significantly throughout the breeding season because older chicks were defended more strongly than younger chicks and eggs. No correlations were however found between defence intensity and laying date, clutch- or brood-size. These results generally do not support either the renesting-potential hypothesis or the positive reinforcement hypothesis but are in accordance with both the age-investment hypothesis and the vulnerability hypothesis, females defended nestlings more often and more vigorously than did males. Given division of labour between sexes and the related reversed sexual dimorphism in size, female Long-eared Owls may be more willing to engage in nest defence simply because they are always nearer eggs and chicks during all breeding stages and are larger/heavier than males; consequently they may allocate more time and energy to this activity. Finally, owls experiencing higher levels of human persecution took smaller risks when defending nests than owls breeding in an undisturbed area
Long living and infrequent breeding in the fat dormouse: a life history adapted to cope with an unpredictable food source
No full textAbstract: We studied the reproductive strategy of a population of fat dormice (Myoxus glis) breeding in nest boxes in a beech forest on the southern Alps, Italy. In eight years of data collection (1991-1998), we observed births only in 1991, 1992, and 1995. We did not observe young during the autumn dispersal in the remaining five years. Reproduction was not correlated with high rainfall, low temperature in summer, or with population density. Reproduction was only observed in years of beech mast seeding. Body condition of adults when they emerged from hibernation did not differ between years with and without reproduction, suggesting that the adults may avoid breeding when the young have a low probability of surviving their first winter. A capture-recapture analysis on individually marked adult fat dormice identified a very high yearly survival rate (0.86-0.92), close to that of large herbivorous mammals and much higher than that typical of other rodent species with similar body size. No influence of sex on survival or recapture probability was detected. The long life span expectancy of an adult dormouse (averaging nine years) is the prerequisite for the infrequent breeding strategy adopted by this rodent species to cope with an unpredictable food source. A high survival rate despite the small body size may have been possible because of the long hibernation time (>6 months). Long life span and intermittent breeding make the life history of fat dormice unique among rodents
Effects of breeding stage, parent sex and human persecution on nest defence behaviour by Long eared owls Asio otus
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