376 research outputs found
The lion in Ghana: its historical and current status
El león en Ghana: su situación pasada y presenteHistóricamente, la población de león (Panthera leo) en Ghana ha sido poco estudiada y su situación actual está poco documentada. Tras los últimos intentos infructuosos de encontrar indicios de la presencia de la especie, son numerosos los autores que opinan que la población de león en Ghana está prácticamente extinguida. En un intento por recabar más datos, desde 2005 hemos venido realizando estudios sobre esta especie en los parques más importantes de Ghana y otras zonas protegidas del país, que se han centrado principalmente en el Parque Nacional de Mole (MNP). Asimismo, hemos examinado los datos publicados con el fin de reconstruir la historia de la presencia del león en el país. Si bien nuestra investigación no aportó datos inequívocos, se recabó información circunstancial que sugiere que aún podría existir una pequeña población de león en el MNP y sus zonas circundantes.Historically, the lion (Panthera leo) population in Ghana has been little studied and its status is poorly documented. Currently, after recent unsuccessful attempts to find signs of the presence of the species, many authors believe that the Ghanaian lion population is most likely extinct. In an attempt to gather more data, since 2005 we have been carrying out lion surveys in the most important parks and other protected areas of Ghana, mainly focusing on Mole National Park (MNP). We have also been extensively reviewing the literature in an attempt to reconstruct the history of the presence of the lion in the country. Although our research has not provided unequivocal evidence of the presence of the lion, we have collected circumstantial evidence that suggests that a small lion population might still be present in MNP and its surrounding areas.El león en Ghana: su situación pasada y presenteHistóricamente, la población de león (Panthera leo) en Ghana ha sido poco estudiada y su situación actual está poco documentada. Tras los últimos intentos infructuosos de encontrar indicios de la presencia de la especie, son numerosos los autores que opinan que la población de león en Ghana está prácticamente extinguida. En un intento por recabar más datos, desde 2005 hemos venido realizando estudios sobre esta especie en los parques más importantes de Ghana y otras zonas protegidas del país, que se han centrado principalmente en el Parque Nacional de Mole (MNP). Asimismo, hemos examinado los datos publicados con el fin de reconstruir la historia de la presencia del león en el país. Si bien nuestra investigación no aportó datos inequívocos, se recabó información circunstancial que sugiere que aún podría existir una pequeña población de león en el MNP y sus zonas circundantes
Has the common genet (Genetta genetta) spread into south-eastern France and Italy ?
The common genet (Genetta genetta) is a small carnivoran that was probably introduced from Maghreb into south-western Europe. We reassessed its easternmost European distribution from 110-mostly new-data collected in south-eastern France and Italy, and tested for potential habitat selection, to finally re-evaluate the role of the Rhone as a geographic barrier against eastward migrations. The species was more frequent in river valleys, wetlands and low-mountainous areas (south-eastern France), but also occurred in high-mountainous zones at the French-Italian border. Our results evidenced a significant increase of records (13-fold the number of occurrences previously known) and an apparent absence of habitat selection by the common genet, suggesting a recent, natural spread from the right bank of the Rhne through a zone of 30km with artificial bridges. We finally provide a synthetic, re-assessed distribution map of the common genet in France and Italy, combining 4317 occurrences from French national databases and the 110 records collected herein
La vita in una goccia d'acqua: spunti per un'azione didattico-educativa.
Il progetto \ue8 stato presentato dal Consiglio Direttivo della SIP (Societ\ue0 Itlaiana di Protistologia ONLUS). L\u2019obiettivo principale di questo progetto \ue8 quello di costituire ed organizzare un\u2019iniziativa didatticoformativapresso gli insegnanti di scienze della scuola secondaria di primo grado, come educatori
della classe dei giovani in et\ue0 scolare, volta a sviluppare le cognizioni scientifico-applicative
sull\u2019importanza dei microorganismi unicellulari eucariotici, comunemente definiti "protisti", in
ambito sanitario e ambientale.
Molto spesso dei protisti, i principali artefici del pi\uf9 grande salto evolutivo nella storia dei viventi,
non esiste il bench\ue9 minimo accenno. La principale ragione di tale incompletezza sta nella non
facile presentazione di tali organismi. I protisti, infatti, hanno dimensioni microscopiche e quindi
non sono visibili ad occhio nudo. Eppure, questi organismi, oltre ad avere un elevata importanza
evolutiva, sono indicatori di qualit\ue0 dell\u2019ambiente oltre ad essere di imponente interesse sanitario. I
protisti di tipo parassitologico sono gli agenti infettanti di malattie molto gravi, quali la malaria, la
toxoplasmosi e la leishmaniosi, tra le pi\uf9 note, e rivestono, oggi, grande importanza nei progetti
d\u2019interesse prioritario per gli interventi istituzionali di sanit\ue0 pubblica in Italia e nel resto del
mondo, ma di essi e delle loro infezioni ben poco sanno gli operatori e gli utenti della scuola
secondaria dove, invece, il messaggio educazionale pu\uf2 essere molto efficiente anche in termini di
prevenzione. Per tutto questo \ue8 molto importante promuovere la conoscenza di tale \u201cmondo
sommerso\u201d nel quale esistono organismi sia da evitare in quanto patogeni (prevenzione primaria)
che da promuovere in ambienti naturali (monitoraggio ambientale e controllo dell\u2019inquinamento).
Il secondo obiettivo \ue8 quello di mettere al servizio di questa iniziativa le conoscenze scientifiche
che vengono dalla ricerca, la pi\uf9 specializzata, come quella perseguita dai ricercatori che nel
progetto svolgono le docenze.
Contestualmente, il terzo obiettivo \ue8 quello di sopperire alla mancanza di informazioni sui protisti,
rendendo evidente, attraverso l\u2019allestimento di una sala didattico-espositiva presso il Museo del
Mare che ha sede nell\u2019Area Marina Protetta (AMP) Torre del Cerrano, l\u2019immagine di questo
microcosmo, che svela i principali fenomeni che regolano la vita sulla Terra e che svolge un
importante ruolo per la conservazione della biodiversit\ue0 sul nostro pianeta. Quest\u2019ultimo obiettivo \ue8
raggiunto anche dagli insegnanti e dai loro studenti, mettendo in uso le conoscenze ottenute nel
corso del progetto, tramite l\u2019utilizzo della sala didattico-espositiva come un laboratorio di ricerca.
In base a quanto sopra esposto possiamo dire che i risultati attesi da questo progetto sono:
1. Accrescimento delle cognizioni tecnico-scientifiche da parte degli insegnanti di scienze della
scuola secondaria arruolati nel progetto nel settore della Protistologia, con particolare riguardo
all\u2019importanza evolutiva e applicativa nel settore ambientale e sanitario dei protisti.
2. Ricaduta di queste cognizioni sugli studenti delle classi coinvolte, come risultato
dell\u2019adempimento didattico dei suddetti insegnanti e rafforzamento delle stesse tramite
l\u2019utilizzazione della sala didattico-espositiva come laboratorio applicativo di lavori di gruppo sul
tema dei protisti e del loro coinvolgimento nella qualit\ue0 dell\u2019ambiente e della salute.
3. Ottenimento della collaborazione tra ricerca universitaria, scuola e aree marine protette in
maniera sinergica
Wakefields due to surface waves in a beam pipe with a periodic rough surface
The problem of the wakefields generated by an ultrarelativistic particle traveling in a long beam tube with a periodic rough surface has been revisited by means of a standard theory based on the hybrid modes excited in a periodically corrugated rectangular waveguide. Slow surface waves synchronous with the particle can be excited in the structure, producing wakefields whose frequency and amplitude depend on the depth of the corrugation. We apply our results to the case of the CERN Large Hadron Collider beam screen and the Linac Coherent Light Source undulator. (19 refs)
Polyvinylpyridine-supported palladium nanoparticles: An efficient catalyst for Suzuki–Miyaura coupling reactions
Palladium nanoparticles (Pd NPs) synthesized by the metal vapor synthesis technique were supported on poly(4-vinylpyridine) 2% cross-linked with divinylbenzene (Pd/PVPy). Transmission electron microscopy revealed the presence of small metal nanoparticles (dm = 2.9 nm) highly dispersed on the PVPy. The Pd/PVPy system showed high catalytic efficiency in Suzuki-Miyaura carbon–carbon coupling reactions of both non-activated and deactivated aromatic iodides and bromides with aryl boronic acids, carried out under an air atmosphere. The high turnover of the catalyst and the ability of the PVPy resin to retain active Pd species are highlighted. By comparing the catalytic performances of Pd/PVPy with those observed by using commercially available Pd-based supported catalysts, the reported system showed higher selectivity and lower Pd leaching
Life-history and diet of two populations of Natrix maura (Reptilia, Colubridae) from contrasted habitats in Sardinia
Aspects of general ecology and population biology of two populations of freeliving viperine snakes (Natrix maura) were studied in Mediterranean localities of the island of Sardinia
(Thyrrenian Sea, Italy). The apparent adult sex-ratio was not significantly different from equality, but males were slightly more numerous than females. The diet consisted mainly of arnphibians, both adults and tadpoles (area A) or fish (area B). Females were significantly longer than males. Reproduction was yearly, and clutch size and female total length were positively correlated. A hundred and seven live
offsprings were obtained from 135 eggs (79.2% of successful incubation rates). The proportion of unsuccessful incubation was not significantly correlated with either female total length or clutch size. There was no evidence of a trade-off between clutch size and offspring size, as hatchlings were no smaller in clutches that were unusually large in relation to maternal body size. Oviposition date was correlated with neither maternal length nor clutch size. lncubation period was significantly correlated with mean hatchling size, but not with either clutch size or maternal length. No female died after
oviposition, thus suggesting a very low incidence of mortality rates dueto starvation and reproductive costs. A case of long-term sperm storage deriving from autumnal mating is described. Population size estimates are provided for both study areas.
Key words: Natrix maura, Ecology, Mediterranean region, Sardinia.Aspects of general ecology and population biology of two populations of freeliving viperine snakes (Natrix maura) were studied in Mediterranean localities of the island of Sardinia
(Thyrrenian Sea, Italy). The apparent adult sex-ratio was not significantly different from equality, but males were slightly more numerous than females. The diet consisted mainly of arnphibians, both adults and tadpoles (area A) or fish (area B). Females were significantly longer than males. Reproduction was yearly, and clutch size and female total length were positively correlated. A hundred and seven live
offsprings were obtained from 135 eggs (79.2% of successful incubation rates). The proportion of unsuccessful incubation was not significantly correlated with either female total length or clutch size. There was no evidence of a trade-off between clutch size and offspring size, as hatchlings were no smaller in clutches that were unusually large in relation to maternal body size. Oviposition date was correlated with neither maternal length nor clutch size. lncubation period was significantly correlated with mean hatchling size, but not with either clutch size or maternal length. No female died after
oviposition, thus suggesting a very low incidence of mortality rates dueto starvation and reproductive costs. A case of long-term sperm storage deriving from autumnal mating is described. Population size estimates are provided for both study areas.
Key words: Natrix maura, Ecology, Mediterranean region, Sardinia.Aspects of general ecology and population biology of two populations of freeliving viperine snakes (Natrix maura) were studied in Mediterranean localities of the island of Sardinia
(Thyrrenian Sea, Italy). The apparent adult sex-ratio was not significantly different from equality, but males were slightly more numerous than females. The diet consisted mainly of arnphibians, both adults and tadpoles (area A) or fish (area B). Females were significantly longer than males. Reproduction was yearly, and clutch size and female total length were positively correlated. A hundred and seven live
offsprings were obtained from 135 eggs (79.2% of successful incubation rates). The proportion of unsuccessful incubation was not significantly correlated with either female total length or clutch size. There was no evidence of a trade-off between clutch size and offspring size, as hatchlings were no smaller in clutches that were unusually large in relation to maternal body size. Oviposition date was correlated with neither maternal length nor clutch size. lncubation period was significantly correlated with mean hatchling size, but not with either clutch size or maternal length. No female died after
oviposition, thus suggesting a very low incidence of mortality rates dueto starvation and reproductive costs. A case of long-term sperm storage deriving from autumnal mating is described. Population size estimates are provided for both study areas.
Key words: Natrix maura, Ecology, Mediterranean region, Sardinia
Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications
African manatees (<i>Trichechus senegalensis</i>) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles <i>Crocodylus suchus</i> and dwarf crocodile <i>Osteolaemus tetraspis</i>) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant
Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications
Abstract. African manatees (Trichechus senegalensis) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant
Total Synthesis of Asparenydiol by Two Sonogashira Cross-Coupling Reactions Promoted by Supported Pd and Cu Catalysts
Asparenydiol, which is an important natural compound with potential pharmacological activities, was synthesized through two Sonogashira cross-coupling reactions catalyzed by supported Pd and Cu catalysts and by a Mitsunobu etherification. The optimization of the Sonogashira couplings allowed the use of catalysts supported on different matrices with good results in terms of catalytic efficiency and yields
Compositional and microstructural characterization of Celtic silver coins from northern Italy using neutron diffraction analysis
Abstract The silver coinage of Celtic tribes settled in northern Italy (IV–I century B.C.) is a topic characterized by several issues, such as chronology, attributions and relationships between emissions produced in different periods. In order to provide numismatists with new data, several specimens, belonging to different typologies, have been analysed with neutron diffraction technique to overcome surface alteration and to provide bulky compositional and structural information of the coins. Measurements performed with the INES diffractometer at the ISIS facility provided essential data for numismatics research. A clear silver debasement occurring between the first and latter emissions has been traced, due to inflation processes which can be related with the increasing power of Roman Republic in the Cisalpine region. Moreover, compositional data enabled for the first time to identify internal evolutions inside typologies defined by numismatists. The silver loss has also been used to establish a relative chronology between different emissions. Other parameters such as texture index, residual strains and grain dimensions have been useful to understand technical aspects of minting procedures during Iron Age
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