1,721,015 research outputs found
Il sito mesolitico dell'INFS di Colunga (Ozzano Emilia - Bologna)
No full textLa stazione mesolitica individuata nel 1986 sui terreni dell'I.N.F.S. (Istituto Nazionale per la Fauna Selvatica) è ubicata a circa 41 m s.l.m., pochi chilometri a valle dai primi rilievi collinari appenninici. Venne frequentata, in maniera occasionale, durante la fase sauveterriana del Mesolitico, da popolazioni che dovevano muoversi sul territorio per ragioni legate all'attività venatoria. Il ritrovamento di una porzione della paleosuperficie, successivamente disturbata da un corso d'acqua a bassa energia, ha consentito di effettuare una serie di rimontaggi sui manufatti litici e di ricostruire le catene operative messe in atto
Modeling the paleogeography of north-western Palaeotethys across the Permian-Triassic boundary: constraints and possible solutions.
Full text linkWe simulated for the first time the palaeogeographic evolution of three thin depositional sequences of the shallow marine western Palaeotethys, deposited in the Southern Alps (SA, ftaly) during the devastating end-Per mia n extinction. The iimulation is calibrated by a rich set of published field data measured in the uppermost Bellerophon Formation-Iowermost Werfen Fm. Data and palaeogeographic maps are located in the palinspastically restored SA area. The employed software is a lpreliminary version of SIMSAFADIM-CLASTIC that simulates: I) the spatial distribution of terrigenous and clastic carbonate, b) rbe fossil cootent, c) the microbial content. The models (maps) "'ere realized as a back-analysis, by calibration with the 3D .architecture of real sedimentary sequences, particularly on the patial distribution of terrigenous-clastic carbonate ratios. The 'mulation covers a peri od of about 70 kyr, whereas each sedimentary sequeoce corresponds to a time-span of 15-20 kyr; dJe low-stand tract spans 5-6 kyr. Models that best match reality t("ere achieved by using a curve of sea level changes obtained empirically. The maximum sea level change is about a dozen lIletres; the study area underwent local short periods of emersion, represented by soil or intertidal carbonates, followed by shallow marine, foreshore facies. The sea level change curve is likely to represent the global reference. We interpret results of the model ~. the hypothesis that the curve of sea level change presented _ re could have been produced by alternating global warming d cooling of the oceans. This curve, obtained by an
• dependent method, would be utilized as an important ronstraint on the numerical global models of coupled tmosphere--ocean circulation. On the contrary, the . appearence of Permian-type tua (fusulinids, foraminifers, 'valves and algae) pre-dating tbe P-T bouodary does not match
e field data because tbe software lacks a few specific functions; ese biologie carbonate components seem to have beeen bstituted by a still-unknown environmental cause producing lites and carbonates of microbialitic origin
Environmental and biotic changes across the Permian–Triassic boundary in western Tethys: The Bulla parastratotype, Italy.
No full textThe sedimentary and biotic evolution of a 190 m interval of shallow marine and lagoonal facies in the Bellerophon and Werfen
formations in the Southern Alps has allowed comparison of western with eastern Tethys: Meishan D section (southern China), Salt
Range (Pakistan) and Abadeh (Iran). Results are as follows:
(1) The upper part of the Bellerophon Fm. (Changhsingian changxingensis–deflecta Zone) shows only modest biotic variation
connected with tectonically driven local variation and perhaps to more general climatic variation. The ?13C decrease starting
in the uppermost 30 m of the Bellerophon Fm. is correlated with decrease in global organic productivity starting about 1 m
below the PTB in Chinese sequences and 20 m below in the Abadeh section. This interval culminated in a regression truncated
by an unconformity–paraconformity (Unconformity 1).
(2) The uppermost Bellerophon Fm. is a ca. 1 m transgressive-regressive sedimentary cycle, the informally named Bulla Mbr
(Changhsingian: Early praeparvus Zone). The maximum flooding interval of this unit possibly had a slight increase in
biodiversity, mainly in foraminifers, algae and brachiopods. The high increase in biodiversity previously reported may, in
part, reflect abundance of biota and organic matter reworked into transgressive and regressive intervals. We suggest partial
correlation of the basal unconformity of the Bulla Mbr (Unconformity 1) with the regressive uppermost Bed 24e of the
Meishan D section marking the disappearance of foraminifers and algae in the eastern Tethys. We also suggest diachronous
disappearance of benthic taxa in Tethys, with the Southern Alps acting like a refugium.
(3) The main extinction (first extinction phase, mainly regarding foraminifers) in the Southern Alps occurred in a thin ca. 25 cm
interval including the uppermost regressive Bulla Mbr, Unconformity 2, and possibly, the basal transgressive bed of the
Tesero Mbr of the Werfen Fm. This interval is correlated in part with regressive Bed 26 of Meishan D section. The main
decrease in abundance and biodiversity in the Southern Alps coincides with appearance of small oolites with crystalline outer
cortex near the basal transgressive tract of the lower Tesero Mbr, a ca. 220 cm sedimentary cycle, that is followed by extension
of microbialitic layers alternating with veritable biostromes with brachiopods and byssate bivalves as salient components
among the algae. Vacated niches favored evolution of conodonts. Hindeodid conodont biodiversity increased with species
developing characteristics of Isarcicella. This interval has been referred to the Changhsingian Late praeparvus Zone and
correlated with Bed 27a–b of Meishan D section. The PTB has been identified in the Bulla section at 1.30 m from the base of
the Werfen Fm. – with the first appearance of Hindeodus parvus defining the base of the parvus Zone – in a microbialitic
layer correlated with Bed 27c of Meishan D section. Around the PTB the major part of the remaining Permian biota
disappeared. Gymnocodiacean algae were the last group to undergo extinction within the Triassic layers. (4) Biodiversity dropped severely in the succeeding bioturbated microbialitic interval from which conodonts are absent. More
humid climate is reflected in a more sandy marine substrate inhabited by Lingula, Unionites and Claraia. Conodonts recurred
in the schizohaline upper part. The succeeding entry of the biozonal markers Isarcicella lobata, Isarcicella staeschei and
Isarcicella isarcica allow discrimination of three conodont biozones. The layer with entry of I. staeschei has been aligned
with Bed 28 of Meishan D section.
The main extinction phase in the western Tethys seems to correspond to a gradual but swift transition from acid-bath to alkalinebath
according to the Deev Jahi model of Heydari and Hassanzadeh [Heydari, E. and Hassanzadeh, J., 2003. Deev Jahi model of
the Permian–Triassic boundary mass extinction: a case for gas..
Lithostratigraphie et evolution des industries du Paleolithique inferieur et moyen a l'Est de Bologne (Italie)
No full text--
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
- …
