1,721,092 research outputs found
Early to late Holocene vegetation and fire dynamics at the treeline in the Maritime Alps
Full text linkWe used pollen, plant macrofossil, and charcoal records to investigate local long-term timberline shifts and changes in vegetation composition in relation to fire activity at the modern upper forest limit (ca. 2,000 m a.s.l.) in the Mont Bégo area, Maritime Alps of France and Italy. The area is an important place for Alpine archaeology because it has thousands rock-art carvings whose age cannot be directly assessed. Our new record confirms the occurrence of distinct land use phases (7,450–7,150, 6,200–4,900, and 4,250–3,700 cal bp), as suggested by earlier studies of rock art typology. Moreover, the vegetation reconstruction from macrofossils, with co-dominance of Pinus and Betula, suggests that early Holocene conditions were moister than in drier inner Alpine valleys, where Larix decidua played a more important role, both in the past as well as in modern timberline forests. After 8,000 cal bp, the timberline shifted upwards and mixed Abies alba and Pinus cembra stands established around the study site. These fire sensitive trees were finally replaced during the Bronze Age (around 4,000 cal bp) by L. decidua, which still dominates the subalpine woodlands in the area today. Our study supports the notion that while the range of A. alba has been reduced at the colder end of its natural distribution, that of L. decidua has been widened by land use changes and fire disturbances to create high alpine wood pastures
An introduction to the submerged prehistoric pile-dwelling in Zambratija Bay on the Croatian Adriatic coast
No full text
Contrasting patterns of precipitation seasonality during the Holocene in the south- and north-central Mediterranean
No full textPollen-based quantitative estimates of seasonal precipitation from Lake Pergusa and lake-level data from
Lake Preola in Sicily (southern Italy) allow three successive periods to be distinguished within the Holocene: an early
Holocene period before ca. 9800 cal a BP with rather dry climate conditions in winter and summer, a mid-Holocene
period between ca. 9800 and 4500 cal a BPwithmaximumwinter and summerwetness, and a lateHolocene period after
4500 cal a BP with declining winter and summer wetness. This evolution observed in the south-central Mediterranean
shows strong similarities to that recognized in the eastern Mediterranean. But, it contrasts with that reconstructed in
north-central Italy, where the mid-Holocene appears to be characterized by a winter (summer) precipitation maximum
(minimum), while the late Holocene coincided with a decrease (increase) in winter (summer) precipitation. Maximum
precipitation at ca. 10 000–4500 cal a BP may have resulted from (i) increased local convection in response to a
Holocene insolation maximum at 10 000 cal a BP and then (ii) the gradual weakening of the Hadley cell activity, which
allowed the winter rainy westerlies to reach the Mediterranean area more frequently. After 4500 cal a BP, changes in
precipitation seasonality may reflect non-linear responses to orbitally driven insolation decrease in addition to seasonal
and inter-hemispheric changes of insolatio
The past distribution of Abies nebrodensis (Lojac.) Mattei: results of a multidisciplinary study
No full textThe present study provides a critical review of the available historical data on the distribution of Abies nebrodensis, a fir tree endemic to Sicily. The only (somewhat ambiguous) references to its occurrence on Mount Etna date back to the 1st century bc and refer back to the 3rd century bc. Although the botanical and forestry literature and the very few surviving herbarium specimens do not prove that A. nebrodensis grew outside the Madonie mountain range, several indications suggest its past occurrence on other Sicilian mountain ranges such as the Erei, Nebrodi, and probably also Sicani mountains. The results of the most recent pollen investigations (still ongoing) point to the disappearance of Abies from most of Sicily by the 1st century bc, and at least since the Middle Ages A. nebrodensis had become extremely rare even on the Madonie mountains. Publications focused on the wooden artefacts from archaeological excavations and the restoration of architectural heritage have provided some information on the past use of fir wood in Sicily, but the species identity of the firs being used remain unresolved. The present review of the past occurrence and distribution of A. nebrodensis suggests that it may have previously occupied a wider ecological niche
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
- …
