920,842 research outputs found
James Scotton, 1985
No full textJames F. Scotton, 1985. Scotton was a member of the faculty at Marquette's College of Journalism and served as its dean from 1978-1984
James Scotton observes as a student types at a computer terminal, 1981
No full textJames Scotton, a professor in Marquette's College of Journalism, observes as a student types at a computer terminal, 1981
Wild Seed Harvesting at Mountainous Species-Rich Grassland in Calcareous Italian Alps
No full textWild harvesting is an efficient option for supplying seed to be used for restoring semi-natural grasslands. Several methods are currently used to implement wild harvesting, but few controlled experiments have investigated its efficiency regarding seed amount and number of species collected. A harvesting trial was conducted in a species-rich, low-productivity grassland of the calcareous Italian Alps (1030 m a.s.l.). Three mechanical methods were tested in three replications using a completely randomized block design: green hay (GH), dry hay (DH), and seed stripping (SS). The number of fertile shoots, mature seeds, and species collected was recorded and compared to the standing seed yield (SSY). GH, DH, and SS harvested approximately 84%, 70%, and 29% of SSY respectively. Forbs were harvested more efficiently than grasses in all methods but in most cases at very low seed amounts per m2 due to their low seed density for SSY. No significant difference among methods was found for the number of species collected as mature seeds, but SS, implemented on larger plots, tended to collect more forb species. Comparing the results with those of other experiments demonstrated that the relatively cool temperature of the seed maturation period at the mountain site favored stronger seed retention and therefore increased the GH and DH efficiency but decreased the SS efficiency. In cool mountain areas, wild harvesting from forb-rich grasslands should be more successful by SS implemented on wide areas and several times over the vegetative season. In less species-rich grassland, GH and DH can efficiently collect high seed amounts of the fewer species present, even if implemented over smaller areas
Seed production in grassland species: Morpho‐biological determinants in a species‐rich semi‐natural grassland
No full textStudying the seed production of herbaceous species can help to conserve grassland
habitats and re-create new high-value grassland surfaces. Studies on grassland seed
production have focused mainly on individual species and traits, without characterizing
their relative importance at the plant community level. The aim of this study
was to investigate the entire seed production process of the main species in a temperate
grassland. Fertile shoots (FS) of twenty-nine grasses and forbs were collected
over 4 years and analysed for sixteen traits that determine inflorescence size, seed
production and seed quality. The per cent viability played a predominant role in
determining the total production of viable seeds. Forbs showed a range of reproductive
strategies, including variable distribution of flowers among growth periods,
number of inflorescences per FS and relationship between seed size and FS density
in the grassland. The flower production for grasses was concentrated in the first
growth period, but this limitation was mitigated by a higher seed dormancy. The
number of viable seeds per FS and seed size were important components of the
reproductive strategy of forbs, with heavy-seeded species being characterised by
high individual densities in the community, but producing few seeds per FS.
Light-seeded species showed an opposite pattern. The results suggest that when
using seeds from semi-natural grasslands for ecological restoration, special attention
should be paid to the seed amount, germinability and viability of forbs, as they
seem to depend more on seed reproduction and have a lower ovule to seed
transformation efficiency
Variations on the Author
No full text“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
Establishing a semi-natural grassland: Effects of harvesting time and sowing density on species composition and structure of a restored Arrhenatherum elatius meadow
No full textSpecies-rich semi-natural grasslands play an essential role in the conservation of European biodiversity. To restore them, existing grasslands may be used as a seed source. A key factor for successful restoration is the transfer of all species of the plant community to the site being restored. This approach, however, often poses practical problems due to variations in species phenology, so that only time-staggered harvesting allows the seeds of many species to be collected. Poor harvesting methods may reduce the number of species transferred from the donor to recipient site. The effects of harvesting at various time points by various methods were evaluated here in a restoration experiment on an ex-arable field in Northern Italy. Propagation materials from the first or second regrowth (or both) of a meadow dominated by Arrhenatherum elatius were collected by four harvesting methods. The materials were spread at the sowing density between 830 and 14360 seeds m2. Species composition and structure of the vegetation were examined during 6 years. Untransferred species were almost exclusively those not present at harvesting as mature seed. Compared with materials from one regrowth period, materials from both regrowth periods significantly increased the number of transferred species per plot (26.5 vs. 28.5, respectively) and the absolute transfer rate (64% vs. 75%). Higher sowing density yielded a greater number of positive than negative effects. It favored stable establishment of donor site species and significantly reduced the presence of weeds. Nonetheless, due to the initial dominance of species with high sowing density, evenness of the restored plots was lower than that at the donor site but increased with time, at least under low- and medium-sowing-density conditions. Multiple harvesting at time points when several species with mature seed are present increases the species transfer rate. Medium
sowing density positively affects restoration development because it promotes the establishment of donor site species with lower sowing density, prevents species with the highest density from dominating the vegetation during the
first few years, and reduces weed cover
Dynamic photogrammetric survey of moving granular masses at laboratory scale.
No full textThe experimental research is aimed at the description, with photogrammetric techniques, of the evolution of the surface of a moving granular mass, in order to contribute to the understanding of the rheology and to the calibration of physical-mathematical-numerical models. The experimental apparatus is constituted by two planes with adjustable inclination: an upstream plane, placed at the inclination of 27.5 °, and a downstream plane at the inclination of 6.5 °. Both planes are square-
shaped with side length of 1.5 m. A fixed volume of dry granular material is released on the upstream plane and followed up to its stop on the downstream plane. two different types of granular material have been used, characterized by different size and form factor. The article describes the degree of automation achieved in the methodological approach and manual work still needed with the hardware and software techniques adopted. Finally, the experimental results are presented for some significant tests as well as the achieved metric quality
Anti-erosion rehabilitation: Effects of revegetation method and site traits on introduced and native plant cover and richness
No full textIn mountainous areas, bare slopes represent often dangerous forms of land degradation that need to be rehabilitated. However, revegetation is usually performed with non-native plants, negatively impacting the natural landscape value. Comprehensive studies, especially on poorly investigated long-term revegetation effects, are therefore essential for the improvement of rehabilitation practices. In this study, four landslides or disused quarries surrounded by well-preserved (semi-) natural vegetation that were revegetated between 1988 and 2002 with non-native only herbaceous or both herbaceous and woody plants were studied 1–9 and 16–31 years after rehabilitation. A total of 111 sampling areas were surveyed for introduced and volunteer species and other important ground cover soil and topography traits. Climatic traits and species' ecological indicators were retrieved from the available databases. The time patterns and ecological spectra of the plant covers were analysed and correlated to the site traits. In the first decade, introduced plants were initially abundant but decreased rapidly. In the long-term, the more stress-tolerant among them still had a considerable cover, especially in fine-textured soils. Native species were established slowly but, due to their higher stress tolerance, dominated in the long-term, especially at more stressful sites. In areas with predominantly herbaceous cover, soil factors, such as gravel content, were more related to the plant cover. In areas with predominantly woody plant cover, the high plant cover was dependent on microclimatic factors, especially aspect. At sites like those studied here, woody species should be always used, but in the form of native plants, as they tend to persist. If herbaceous species are unavailable in native forms, their introduction should be avoided in areas not exposed to erosion, whereas poorly stress-tolerant non-native plants should be used in steep areas as they create a fast but short-lasting cover compensated in the long term by the establishment of native species
Efficiency of mechanical seed harvesting for grassland restoration
No full textMaintaining and re-creating species-rich semi-natural grasslands are important issues in current agricultural
policy in Europe. The seed that is required for their establishment can be obtained through direct harvesting
from semi-natural herbaceous vegetation. To test the efficiency of mechanical seed harvesting on donor
Arrhenatherion elatioris grasslands, experiments were performed in northern Italy and eastern Czech Republic.
Trials were organized with a randomized block design and involved harvesting as green hay (grass mowing and
immediate collection), dry hay (grass mowing and collection after drying on the field), direct combining (grass
cutting and threshing at the same combine passage) and seed stripping with pull-type equipment (seed removal
without grass cutting with a brush harvester pulled by a tractor). Harvesting was carried out at the time of
maximum ripe standing seed yield (SSY) in the first and second regrowth. The harvested materials were analysed
for seed number and weight and compared with the SSY. The species composition and phenology were also
surveyed. In all methods, the seed mixture obtained contained the species present as seed at harvest time and
was correlated with SSY. However, with regard to the seed number collected, the harvesting efficiency changed
in relation to species group (grasses or forbs), individual species, seed maturation and regrowth. The most
efficient method was harvesting as green hay (efficiency of approximately 71% of SSY and seed mixture composition
that was very highly correlated with SSY). The least efficient methods were direct combining (30% of
SSY and negative selectivity against light or difficult to detach seeds, producing the highest mean 1000-seeds
weight) and harvesting as dry hay (39% of SSY and a high sensitivity to seed maturation level). Seed stripping,
operated with downward brush rotation at the leading edge, resulted in an intermediate efficiency (60% of SSY
and a seed mixture composition highly correlated with SSY). The harvesting efficiency for seed number was
higher at the first regrowth than the second one for both species groups and, especially at the second regrowth,
higher for forbs than for grasses. Especially forb harvesting presented a problem with regard to the species
number collected. The problem was, not due to harvesting inefficiency but rather for phenological reasons, as
several forbs did not produce fertile stems at the first or second regrowth and some other early flowering species
had already shed the seed at the harvesting time. These results improve our understanding of factors affecting
the efficiency of mechanical harvesting and will help in the preparation of efficient harvesting programs
Recursive operability analysis as a tool for ATEX classification in plants managing explosive dusts
No full textSafety and prevention in workplaces are important issues, especially regards to risks with serious consequences for health and infrastructures, such as dust explosions, which have caused several industrial accidents during the last centuries and, actually, represent a critical issue in the industrial framework. The current European legislation, referred to as ATEX directive, identifies ATEX zones as parts of the plant where explosive atmospheres can be generated. In this work, a modified version of the classic Recursive Operability Analysis method, specifically tailored to define with an automatic procedure the ATEX zones related to flammable dust clouds, is proposed. The method is fast and effective, allowing for an automatic generation of fault trees from which the probability of occurrence defining the specific ATEX zone type can be estimated. This technique was successfully implemented in a chemical plant dedicated to the mixing of inert powders with a stearate powder, a hazardous dust classified as strongly explosible. The extent of all the ATEX zones identified within the plant was simulated with the ALOHA software, treating the dispersed dust cloud of stearate as a dense gas cloud. From the results, it was possible to identify not only type and extension of all the ATEX zones but also either the most critical parts of the plant or the most dangerous activities (e.g. human errors in the use of the forklift was found to account for about 97.7% to explosion probability in this type of plant)
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