1,721,399 research outputs found
Bee and beekeeping research in a rapidly changing world: Advancements and challenges
Full text linkPopulations of pollinating insects are in concrete decline globally. Many wild bees are now considered at risk of extinction, disappearing from many habitats. In the last decade, high attention has been paid to the rarefaction of the populations of Apis mellifera, the common honeybee. Populations of this species have suffered significant numerical losses since 2006–2007 in the USA, when the phenomenon of colony collapse disorder (CCD) was first described by B. Oldroyd [3]. The great interest in the decline of this species is justified by the fact that honeybees, in addition to providing important foods and products such as honey, pollen, propolis, royal jelly and venom [4,5,6,7,8], have long been employed for the pollination service [9,10]. Therefore, their decline poses a serious threat to the production of important crops for human consumption globally, with major repercussions on yields.
To face this worrying scenario, we should focus on the complexity of the trophic networks in which the honeybee participates, acting as a reliable indicator of the level of environmental sustainability of a given habita
Bayesian multiscale mixture of Gaussian kernels for density estimation
No full textIn this paper we discuss some preliminary results related to a novel
Bayesian nonparametric method for multiscale density estimation. Specifically, we
extend the model by [1]—originally developed for compact sample spaces—to deal
with data taking values in the whole real line R. By means of an infinitely-deep
binary tree of kernels, we are able to construct a multiscale mixture model able to
approximate densities with varying degrees of smoothness and local features. Sampling
from the posterior distribution is available with a Markov Chain Monte Carlo
method
"Vittorio D." (M. Canale, A. Morri, 2010)
No full textRecensione del film documentario "Vittorio D." (M. Canale, A. Morri, 2010
Bactrocera oleae-induced olive VOCs routing mate searching in Psyttalia concolor males: Impact of associative learning
No full textOlfaction is a key sense routing foraging behaviour in parasitoids. Preferences for food, mate and host stimuli can be innate in parasitic wasps. Alternatively, learning-mediated mechanisms play a crucial role. Females of the braconid parasitoid Psyttalia concolor exploit olfactory cues arising from tephritid hosts and related microhabitats. However, little is known on the olfactory stimuli routing males searching for mates. In this study, we focused on the attractiveness of Bactrocera oleae-induced olive volatiles towards P. concolor males. Furthermore, we evaluated learning occurrence in virgin males, when trained for selected unattractive volatile organic compounds (VOCs) associated with mate rewards. (E)-β-Ocimene, α-pinene and limonene attracted virgin males in Y-tube bioassays. Unattractive VOCs evoked positive chemotaxis after associative learning training. P. concolor males exposed to VOCs during a successful or unsuccessful mating, showed short-term preference for these VOCs (<1 h). However, memory consolidation was strictly dependent on reward value. Indeed, males experiencing a successful mating showed a fast consolidation into protein dependent long-term memory, appearing after 24 h. On the other hand, males experiencing a less valuable training experience (i.e. unsuccessful courtship), did not show consolidated memory after 24 h. Overall, our findings suggest that P. concolor virgin males may exploit VOCs from the host microhabitat to boost their mate searching activity, thus their reproductive success. However, since learning is a costly process, P. concolor males retained durable memories just in presence of a valuable reward, thus avoiding maladaptive behaviours
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
Historical and Archaeological Data for the Ancient Road Network in Western Sicily from the Roman Period to the Norman Age
No full textIn this paper, the authors examine a district of the north-central Sicily, from the Madonie Mountains to the mountains going SW towards Vicari and Castronovo, where targeted archaeological surveys have been carried out during the last forty years. The aim is to understand the development of the road network system from the Roman Period to the Norman Age and, through this, to understand the population dynamics of these internal areas of Sicily. The focus are a sector of the Palermo-Termini-Taormina route (known as the via Messina per le montagne), between Polizzi Generosa, Petralia and Gangi, and a district connecting this route with the area of Vicari and Castronovo. Common to the two districts is the presence of properties, attested by sources, belonging to the Teutonic Knights of the Magione (Palermo); in the both districts, also, the road network could be connected to the vie Francigene system
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
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