1,666 research outputs found
Climatic and Biotic Events of the Paleogene
No full textThis special issue of Climate of the Past offers a venue for scientific papers focused on better understanding prominent changes in climate and evolution that occurred during one of the most dynamic intervals in Earth's history: the Paleogene. We aim to provide a collection of contributions that focus on current research, including but not limited to that presented at the international meeting "Climatic and Biotic Events of the Paleogene (CBEP 2014)", which was held on 1–6 July 2014 in Ferrara, Italy. We invite contributions resulting from both terrestrial and marine archives. http://www.clim-past.net/special_issue85.htm
Climatic and Biotic Events of the Paleogene 2014, CBEP 2014
No full textThis special issue include the scientific contributes, short notes and abstracts, presented at the International Meeting: Climatic and Biotic Events of the Paleogene, CBEP 2014, held in Ferrara, Italy, July, 1-6, 2014, 10 thematic sessions. More than 140 participants from 20 countries attended the meeting, included the most famous experts. the http://web.fe.infn.it/cbep2014
2. Genetic prothrombotic factors in children with otogenic lateral sinus thrombosis: five case reports
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Genetic prothrombotic factors in children with otogenic lateral sinus thrombosis: five case reports
Author(s): Zangari, P (Zangari, Paola)1; Messia, V (Messia, Virginia)1; Viccaro, M (Viccaro, Marika)2; Bottero, S (Bottero, Sergio)2; Randisi, F (Randisi, Francesco)3; Marsella, P (Marsella, Pasquale)2; Luciani, M (Luciani, Matteo)4; Locatelli, F (Locatelli, Franco)4
Source: BLOOD COAGULATION & FIBRINOLYSIS Volume: 23 Issue: 2 Pages: 158-163 DOI: 10.1097/MBC.0b013e328349cafb Published: MAR 2012
Times Cited: 0 (from Web of Science)
Cited References: 20 [ view related records ] Citation Map
Abstract: Lateral sinus thrombosis (LST) is an uncommon, but life-threatening complication of both acute and chronic otitis media. There is some evidence that acquired or hereditary prothrombotic disorders are risk factors for LST. The aim of this work was to evaluate the role of thrombotic screening, anticoagulant therapy or prophylaxis in patients with either acute or chronic otitis media and LST. The medical records of five children hospitalized at Pediatric Hospital Bambino Gesu of Rome because of acute or chronic otitis media complicated by mastoiditis and LST were reviewed. All children underwent laboratory workup for hypercoagulability. All the five children were found to be heterozygote for the C677T MTHFR mutation and a child presented also heterozygosity for factor V Leiden mutation. They have been successfully treated with anticoagulant therapy without sequels. Children with acute or chronic otitis media may have a prothrombotic tendency that becomes clinically evident because of the inflammatory state. Patients with a family and/or personal history of thrombosis and/or thrombophilic conditions need anticoagulant prophylaxis also in the absence of clear signs of LST. Treatment with low molecular weight is successful in patients with LST. Blood Coagul Fibrinolysis 23:158-163 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins
High-resolution planktonic foraminiferal analysis from the Cretaceous–Tertiary boundary at Ain Settara (Tunisia): evidence of an extended mass extinction
No full textThe Ain Settara section, located in the Kalaat-Senan area of north^central Tunisia, spans the Cretaceous/Tertiary (K/T) boundary which is characterized by a red layer and a thin non-bioturbated boundary clay. Sediment accumulation across the K^T boundary at Ain Settara was probably interrupted by three short hiatuses and/or condensed sedimentation. The first hiatus occurs at the top of the CF1 Zone; the second hiatus/condensation occurred just below the boundary clay and the third hiatus at the P0/P1a boundary, in the earliest Danian. These
hiatuses are marked by weak unconformities, bioturbation and sudden disappearances/appearances of species which are known to disappear/evolve sequentially in continuous sections. Quantitative high-resolution planktonic foraminiferal analysis across zones CF1(upper), P0 and P1a (1) reveals an extended and selective mass extinction.
All 41% of the species which disappeared at or below the K/T boundary are rare to very rare and primarily ecologically specialized keeled deeper-dwelling tropical^subtropical forms (Globotruncana, Globotruncanita, Gublerina, Planoglobulina, Rosita (Contusotruncana), Racemiguembelina). Their combined relative abundance varies between 10% and 15% of the total population at the end of the Maastrichtian. The K/T crisis thus appears more catastrophic when viewed in tropical^subtropical assemblages and based on analysis of larger species (s200 Wm) which preferentially includes the more specialized forms, though, in fact, the K^T mass extinction actually involved a relatively small part of the foraminiferal population in terms of relative abundance. The pattern of extinction and changes in dominant population at Ain Settara appear to be very similar to the planktonic foraminiferal turnover of the other north-central Tunisian sections (El Kef, Elles). The selective mass extinction pattern suggests that the catastrophic effects of
the bolide impact superimposed those related to long-term environmental changes, such as variations in temperature, sea-level and associated water-mass changes
Prefazione a V. Kornaros, Erotokritos, romanzo d'amore e cortesie, a cura di C. Luciani
No full textIntroduzione al contesto storico letterario dell'isola di Creta durante i secoli della dominazione letteraria e in particolare del periodo durante il quale fu prodotto il romanzo di V. Kornaros (fine XVI inizi del XVII secolo)
Planktonic foraminifera and environmental changes across the Bonarelli Event (OAE2, latest Cenomanian) in its type area: a high-resolution study from the Tethyan reference Bottaccione section (Gubbio, central Italy).
No full textThe worldwide latest Cenomanian Oceanic Anoxic Event 2 (OAE2) was investigated for the planktonic foraminiferal assemblages in the type area of its sedimentare expression, the Corg–rich Bonarelli Level (Gubbio,
central Italy). The 313 kyr preceding the onset of OAE2 and the 153 kyr following the end of this event were analyzed in the deep-water setting of the Bottaccione section (Umbria-Marche Basin). For the first time, a highresolution approach and quantitative methods were applied.Several events and biotic changes, including the acme and crisis of different genera, were recognized. They provide evidence of a progressive and rapid deterioration of paleoenvironmental conditions, reaching a climax coincident with the Bonarelli Event, and of the subsequent, gradual (although not complete) recovery. Although no major mass extinction in planktonic foraminifera occurred across the Bonarelli Event, the extinction of the most specialized forms, i.e., the rotaliporids, and Globigerinelloides bentonensis, is recorded just bifore its onset. The observed pattern of marked changes in planktonic foraminiferal assemblages indicates five discrete phases of different degrees of environmental perturbation within the marine ecosystem. Phase I (313–55 kyr prior to the onset of OAE2) is characterized by a high planktonic foraminiferal abundance and diversity that imply a relatively stable environment, with different ecological niches occupied and stratified water column. On the other hand, relatively high percentages of hedbergellids and heterohelicids indicate a general meso-eutrophic environment and a well-developed oxygen minimum zone. Episodes of increased eutrophic conditions are indicated by pulses in abundance of radiolarians. A well-developed oxygen minimum zone may be related to a long-term change that precedes the onset of OAE2 (mid-Cenomanian Event). The most dramatic changes took place during Phase II and encompassed the last 55 kyr precedine deposition of the Bonarelli Level. The onset of a highstress environment is clearly shown by the shift to a distinctly unstable planktonic foraminiferal structure, characterized by low species diversity and marked foraminiferal changes and events. Some of these took place at the same time (the rotaliporid crisis, the heterohelicid decline, the Hedbergella-Schackoina shift, the onset of the ‘large form eclipse’ when larger 150 micron forms temporarily
disappeared) followed by other sequential events (onset of dwarfism, schackoinid acme, and hedbergellid acme). The 150 micron forms temporarily disappeared) followed by other sequential events (onset of dwarfism, schackoinid acme, and hedbergellid acme). The above-mentioned changes and events indicate for Phase II an increased surface productivity, enhanced oxygen minimum zone, and marked rapid changes of ecological parameters (e.g., temperature, salinity, trace metals). These marked foraminiferal changes culminate at the base of the Bonarelli Level with the temporary disappearance of all planktonic foraminifera. Phase III (100–900 kyr) coincides with the Bonarelli Level deposition and is characterized by highly eutrophic conditions, as indicated by radiolarian proliferation. Phase IV (35 kyr), similar to phase II except for the absence of rotaliporids, is characterized by the proliferation of the opportunistic hedbergellids and schackoinids, indicating that the environment remained ecologically unstable. The end of ‘large form eclipse’ marks the base of Phase V. During Phase V (118 kyr), planktonic
foraminiferal abundance and diversity return to values comparable to those of Phase I, showing the gradual recovery of the ecosystem. However, high numbers of hedbergellids and heterohelicids suggest that the environmental perturbation related to the Bonarelli Event did not end during this phase, but continued well beyond deposition of the organic-rich layers. Our analysis shows that, in deep-water settings, the severe paleoenvironmental perturbation induced by the Bonarelli Event led to assemblages dominated by the small-sized, opportunistic hedbergellids and schackoinids. At the same time, the small-sized and presumably low-oxygen-tolerant, opportunistic heterohelicids underwent a marked decline. This scenario may be related to the exceptionally high-nutrient and low oxygen content of the seawater, but also to variation of other ecological parameters. The perforate, elongated chambers and tubulospines of schackoinids may represent the best survivorship tool to have achieved better oxygen and nutrient uptake. We infer that schackoinids are useful indicatore for extremely stressed environments in low- to middlelatitude, open-marine, deep-water settings during the Late Cretaceous
Biotic and geochemical evidences of the main Pleistocene oceanographic and climate events in the East New Zeland Pacific Ocean (IMAGES site MD97-2114, Chatham Rise)
No full textEcological and evolutionary response of Tethyan planktonic foraminifera to the middle Eocene climatic optimum (MECO) from the Alano section (NE Italy)
No full textThe enigmatic middle Eocene climatic optimum (MECO) is a transient (~500kyr) warming event that significantly interrupted at ~40 Ma the long-term cooling through the middle and late Eocene, eventually resulting in establishment of permanent Antarctic ice-sheet. This event is still poorly known and data on the biotic response are so far scarce. Here we present a detailed planktonic foraminiferal analysis of the MECO interval from a marginal basin of the central-western Tethys (Alano section, northeastern Italy). The expanded and continuous Alano section provides an excellent record of this event and offers an appealing opportunity to better understand the role of climate upon calcareous plankton evolution. A sapropel-like interval, characterized by excursions in both the carbon and oxygen bulk-carbonate isotope records, represents the lithological expression of the post-MECO event in the study area and follows the δ18O negative shift, interpreted as representing the MECO warming.High-resolution quantitative analysis performed on both >38 μm and >63 μm fractions reveals pronounced and complex changes in planktonic foraminiferal assemblages indicating a strong environmental perturbation that parallels the variations of the stable isotope curves corresponding to the MECO and post-MECO intervals. These changes consist primarily in a marked increase in abundance of the relatively eutrophic subbotinids and of the small, low-oxygen tolerant Streptochilus, Chiloguembelina and Pseudohas-tigerina. At the same time, the arrival of the abundant opportunist eutrophic Jenkinsina and Pseudoglobigerinella bolivariana, typical species of very high-productivity areas, also occurs. The pronounced shift from oligotrophic to more eutrophic, opportunist, low-oxygen tolerant planktonic foraminiferal assemblages suggests increased nutrient input and surface ocean productivity in response to the environmental perturbation associated with the MECO. Particularly critical environmental conditions have been reached during the deposition of the sapropel-like beds as testified by the presence of common giant and/or odd morphotypes. This is interpreted as evidence of transient alteration in the ocean chemistry.The enhanced surface water productivity inferred by planktonic foraminiferal assemblages at the onset of the event should have resulted in heavier δ13C values. The recorded lightening of the carbon stable isotope preceding the maximum warmth therefore represents a robust indication that it derives principally by a conspicuous increase of pCO2. The increased productivity of surface waters, also supported by geochemical data, may have acted as mechanism for pCO2 reduction and returned the climate system to the general Eocene cooling trend. The oxygen-depleted deep waters and the organic carbon burial following the peak of the MECO event represent the local response to the MECO warming and suggest that high sequestration of organic matter, if representing a widespread response to this event, might have contributed to the decrease of pCO2 as well. Though the true mechanisms are still obscure, several lines of evidence indicate a potential pressure on planktonic foraminiferal evolution during the MECO event including permanent changes besides transient and ecologically controlled variations
Biotic response to anoxic events:the case history of the cenomanian-Turonian Antruiles section (Dolomites, northern Italy).
No full textNannofossili calcarei e foraminiferi planctonici nei livelli anossici, pelagiti ritmiche e torbiditi del cenomaniano-Turoniano nelle dolomiti Ampezzane.
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