1,721,128 research outputs found
Cultivating urban landscapes: horticulture
No full textFor a long time urban horticulture has represented a marginal activity generally for the elderly, after their retirement or as a part-time activity, as opposed to a main economic activity. However, in the context of post-modern society, horticulture is becoming more popular and more visible, as an activity with educational or rehabilitation purposes or as a hobby for highly motivated gardeners, individual or groups, with no previous experience but keen to experiment with cultivating practices. The interest in urban gardening has grown considerably, assuming many forms and characteristics in different contexts both at global and local levels. The phenomenon seems to be a response to a wide range of needs that goes well beyond the production of food, as it often contributes to promote social inclusion, as well as protection and restoration of urban green areas. For many people taking care of a vegetable patch or a garden is a great way to rediscover their bond with nature, to let off steam and get away from the hustle and bustle of daily life. At the same time allotment gardens become a meeting place for the elderly or turn into an outdoor classroom where children can discover nature's way of teaching. Even more important perhaps is when vegetable gardens are located in healthcare facilities and used for their therapeutic function, thus providing support and motivation during treatment or rehabilitation. And so it seems as though garden plots are becoming a bottom-up strategy to combat the limitations and paradoxes of the current economic model
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
Statistical model and performance analysis of a novel multilevel polarization modulation in local "twisted" fibers
No full textTransmission demand continues to grow and higher capacity optical communication systems are required to economically meet this ever-increasing need for communication services. This article expands and deepens the study of a novel optical communication system for high-capacity Local Area Networks (LANs), based on twisted optical fibers. The complete statistical behavior of this system is shown, designed for more efficient use of the fiber single-channel capacity by adopting an unconventional multilevel polarization modulation (called bands of polarization). Starting from simulative results, a possible reference mathematical model is proposed. Finally, the system performance is analyzed in the presence of shot-noise (coherent detection) or thermal noise (direct detection)
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
Evaluating SOA nonlinearity effects by high-order susceptibility on constant envelope signals in WDM systems
Full text linkNonlinearity effects, arising within a semiconductor
optical amplifier, have been deeply investigated with particular
interest for exploiting them in wavelength conversion. This application
shrinks the research area to a precise scenario: a strong
pump signal travels through the active medium simultaneously
with a modulated signal to be converted. In this case it is possible
to neglect the spectral distribution of the optical power and phase
relationship between propagating signals. SOAs have been also
studied as line amplifiers for WDM phase modulated signals.
Aim of this paper is to extend the propagation model in a SOA,
in order to simulate nonlinearities occurring in the amplification
of a WDM comb signal evaluating FWM on constant envelope
modulation schemes (DPSK). This can be carried out thanks
to an enanched analytical model based on the optical field and
medium interaction, overcoming the wide-used Rate Equation
approach, which is based on the overall photons density
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