1,720,973 research outputs found
Is agglomeration really good for growth? Global efficiency, interregional equity and uneven growth
No full textAccording to NEG literature, spatial concentration of industrial activities increases growth at the regional and aggregate level without generating regional growth differentials. This view is not supported by the data. We extend the canonical model with an additional sector producing non-tradable goods which benefits from localized knowledge spillovers coming from the R&D performing industrial sector. This view, motivated by the evidence, generates both an anti-growth and a pro-growth effect of agglomeration for both the deindustrializing and the industrializing regions and leads to two novel results: 1) when agglomeration takes place, growth is lower in the periphery; 2) agglomeration may have a negative effect on the growth rate of real income, both at the regional and at the aggregate level. Our conclusions have relevant policy implications: contrary to the standard view, current EU and US regional policies favouring industrial dispersion might be welfare-improving both at the regional and the aggregate level and may reduce regional income disparities
Structural change and growth in a NEG model
No full textThis paper presents a New Economic Geography model of structural change, agglomeration and growth. By assuming the same non-homothetic preference structure as Murata (2008), we obtain similar results in that a progressive reduction of trade costs allows the economy to pass from a pre-industrialized to an industrialized stage and then, within the latter, from a dispersed to an urbanized regime. However, the introduction of capital accumulation and the dynamic setting of our model open the door to a richer set of implications. First, an additional stage is introduced as, for some intermediate values of trade costs, a multiple equilibria regime emerges with the symmetric and the core-periphery equilibria stable at the same time. Second, the in- troduction of non-homotheticity introduces a new channel through which growth is affected by trade costs and agglomeration. In particular, integration is always growth-enhancing while ag- glomeration is growth-detrimental
Effects of clipping on the nitrogen economy of four Triticum species grown in a Mediterranean environment
No full textDual-purpose utilization (herbage + grain) of ancient wheats and old durum wheat cultivars provides an interesting option for mixed farming systems in Mediterranean environments. Interest towards these species is partly due to their low nitrogen (N) requirements, but little information is available about their N economy, particularly under dual-purpose utilization. In this two-year field trial carried out in Sardinia (Italy), we assessed whether the morpho-physiological differences between emmer, einkorn, durum and Khorasan wheat translated into different N economies, and whether these economies were differentially impacted by dual-purpose utilization. At both clipping and anthesis, biomass accumulation played a key role in the genotypic variability in N uptake. At clipping, einkorn cultivars had produced the greatest amount of biomass and removed the greatest amount of N (74 kg ha−1) thanks to their late terminal spikelet; whereas Cappelli, Khorasan and Padre Pio showed the greatest biomass production and N uptake at anthesis (212 kg ha−1) owing to their tallness and morphology. The large genotypic variation observed in total N uptake at anthesis levelled off at maturity, mainly because of the N losses occurring at the canopy level after anthesis in cultivars Cappelli, Khorasan and Padre Pio. On average, clipped crops showed a lower (by about 46 kg ha−1) total N uptake at maturity compared with unclipped crops, but dual-purpose utilization did not negatively affect the N uptake if the N removed by clipping was taken into account. Clipping did not negatively affect N partitioning to the grain as the N harvest index increased after clipping as a consequence of the increased harvest index
Ancient wheat species are suitable to grain-only and grain plus herbage utilisations in marginal Mediterranean environments
Full text linkThanks to their low fertilization requirements and high consumer demand, ancient wheats and old durum wheat cultivars represent an attractive option for the marginal areas of Mediterranean environments no longer cultivated due to the low grain yields attainable using modern wheat cultivars. Dual-purpose utilization may increase their value in these cropping systems, but no information is available on the suitability of ancient wheat species to this type of utilization. To fill this gap, Khorasan, einkorn, and emmer wheats, clipped at the terminal spikelet stage or left unclipped, were compared in a two-year field trial. The grains were sown in the month of October, in Sardinia (41°N, 80 m asl), Italy, on low-fertility soils and with low-medium fertilization rates. Einkorn cultivars produced the highest biomass yield (2–3 t ha−1), reflecting the longer time to the onset of the terminal spikelet stage (119–138 days). After clipping, all species recovered their ability to intercept radiation to the levels of the unclipped crops, but clipping lowered their radiation use-efficiency. Grain yield was not penalized by clipping: the increase in the harvest index compensated for the decrease in biomass. Here we show for the first time that ancient wheat species are suitable for dual-purpose utilization (herbage plus grain in the same season) rendering them valuable for marginal areas; this was because the early sowing adopted for dual-purpose utilization allowed them to take full advantage of their lateness in terms of herbage yield, and to bring flowering forward (i.e. make it earlier) so that a satisfactory grain yield was obtained, even under severe water stress. Dual-purpose utilization of ancient wheats increases the sustainability of mixed cropping systems, by making herbage available to animals in a critical period, without decreasing the grain yield attainable after grazing in the same season
Triticale cultivar mixtures: Productivity, resource use and resource use efficiency in a Mediterranean environment
No full textCultural systems based on mixtures of varieties may be more successful in resource use and resource use efficiency than those based on single varieties. Two triticale cultivars of different phenology (Bienvenu, intermediate; and Oceania, spring) grown in pure stands were compared with mixtures of the two (25:75; 50:50 and 75:25). Field experiments were carried out in Sardinia (Italy) in five experiments created by combining seasons, sowing date and sites. At the terminal spikelet of Bienvenu, the best mixtures produced 38, 89 and 82 % more biomass than Bienvenu in pure stand, depending on the experiment, due to a higher crop growth rate associated with a higher RUE (r = 0.60*). In the case of dual purpose utilization, this means that the winter herbage production of triticale at the terminal spikelet stage of an intermediate or winter cultivar is improved when mixed with a spring cultivar, at least in the Mediterranean environment explored here. Complementarity and differences between mixtures and pure stands in biomass production by anthesis were the exception rather than the rule. By the anthesis of Oceania, mixtures only produced more biomass than the Oceania pure stand on three occasions (11.8 and 11.9 t ha−1 vs. 9.3 t ha−1 and 10.7 t ha−1 vs. 8.7 t ha−1). In these cases, the superiority of the mixtures was due to a higher intercepted PAR (also reflected in greater transpiration), attributable to the pattern of LAI development. Differences in grain yield were only expressed when a cold stress during anthesis compromised the grain set of the spring cultivar. Here, mixtures played a fundamental role in increasing the stability in grain yield, suggesting that differences in the developmental rate between mixture components reduced the mixture sensitivity to specific abiotic stresses
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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