The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
Robert H. Dott - One of the best experts on this subject based on the ideXlab platform.
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Episodic Event deposits versus stratigraphic sequences shall the twain never meet
Sedimentary Geology, 1996Co-Authors: Robert H. DottAbstract:Abstract In the early half of the 20th century, questions were raised about different rates of deposition reflected in the stratigraphic record and of small gaps or diastems. Even more discussion centered upon rhythms and cycles of deposition—at one extreme were glacial varves and at the other were Carboniferous cyclothems. After World War II, interest in stratigraphic cycles declined. Then the turbidity current revolution stimulated interest in Event deposits, which interest has surged again recently with a focus upon storm deposits. Meanwhile, the recent dramatic growth of sequence stratigraphy has rekindled interest in both cyclicity and eustasy. The two themes—Events and cycles—should be better integrated, for there is considerable confusion about the interpretation of high-frequency sequences. There is also a need to reconcile the current fad for Milankovitch-related sedimentary cycles versus more or less random Event deposits. The most familiar Event deposits are turbidites in deep-water and tempestites in shallow-water environments. More subtle are the diastems, which include non-depositional surfaces as well as scoured surfaces. Other processes that can produce Event deposits include avalanches and tsunamis. Potentially, any type of Event deposit could be mistaken for a sequence boundary. For example, submarine megabreccias could be formed either by a seismic Event unrelated to any sea level change, or by slope failure resulting from a eustatic fall associated with a sequence boundary. To surmount the intellectual barrier to alternate interpretations requires careful attention to processes, time resolution, and objective tests for periodicity.
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Episodic Event deposits versus stratigraphic sequences—shall the twain never meet?
Sedimentary Geology, 1996Co-Authors: Robert H. DottAbstract:Abstract In the early half of the 20th century, questions were raised about different rates of deposition reflected in the stratigraphic record and of small gaps or diastems. Even more discussion centered upon rhythms and cycles of deposition—at one extreme were glacial varves and at the other were Carboniferous cyclothems. After World War II, interest in stratigraphic cycles declined. Then the turbidity current revolution stimulated interest in Event deposits, which interest has surged again recently with a focus upon storm deposits. Meanwhile, the recent dramatic growth of sequence stratigraphy has rekindled interest in both cyclicity and eustasy. The two themes—Events and cycles—should be better integrated, for there is considerable confusion about the interpretation of high-frequency sequences. There is also a need to reconcile the current fad for Milankovitch-related sedimentary cycles versus more or less random Event deposits. The most familiar Event deposits are turbidites in deep-water and tempestites in shallow-water environments. More subtle are the diastems, which include non-depositional surfaces as well as scoured surfaces. Other processes that can produce Event deposits include avalanches and tsunamis. Potentially, any type of Event deposit could be mistaken for a sequence boundary. For example, submarine megabreccias could be formed either by a seismic Event unrelated to any sea level change, or by slope failure resulting from a eustatic fall associated with a sequence boundary. To surmount the intellectual barrier to alternate interpretations requires careful attention to processes, time resolution, and objective tests for periodicity.
D. P. Cyrus - One of the best experts on this subject based on the ideXlab platform.
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changes in the fish community of the st lucia estuarine system south africa following cyclone gamede an Episodic cyclonic Event
Estuarine Coastal and Shelf Science, 2020Co-Authors: Quintin Schutte, L Vivier, D. P. CyrusAbstract:Abstract Lake St Lucia, the largest estuarine lake system in Africa, has been closed since 2002 except for a five month period in 2007 when the mouth was breached by an Episodic Event, Cyclone Gamede. Mouth opening in 2007 was preceded by five years of low lake levels and hypersaline conditions, which changed the fish species composition and greatly reduced marine fish species diversity. Mouth opening in March 2007 caused the system to partially fill and marine salinities were restored, allowing recruitment of marine species. This study assessed changes in the fish community during the period 2008–2011 following mouth closure after the Cyclone Gamede breaching Event. A total of 19,726 fish representing 61 species were collected using seine netting at six sites across the system during biannual sampling between 2008 and 2011. After mouth closure in August 2007, salinities increased and North Lake became hypersaline during 2009–2010. Marine species initially dominated in terms of species number, but freshwater and estuarine species became progressively more abundant, notably Oreochromis mossambicus and Ambassis ambassis. The number of species decreased from 51 in 2008 to 37 in 2011, with 22 marine and two estuarine species being lost from the system. The abundance of marine species decreased by >75% as the system became progressively more saline and the closed mouth limited recruitment to infrequent overtopping Events. Changes in the fish community were largely driven by salinity changes across the three main regions of the system. Although management efforts to increase freshwater inflow from the Mfolozi estuary was successful, rapid siltation of the mouth area is a concern.
Aidan J. Horner - One of the best experts on this subject based on the ideXlab platform.
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United we fall: all-or-none forgetting of complex Episodic Events
Journal of experimental psychology. General, 2019Co-Authors: Bardur Hofgaard Joensen, M. Gareth Gaskell, Aidan J. HornerAbstract:Do complex Event representations fragment over time, or are they instead forgotten in an all-or-none manner? For example, if we met a friend in a cafe and they gave us a present, do we forget the constituent elements of this Event (location, person, and object) independently, or would the whole Event be forgotten? Research suggests that item-based memories are forgotten in a fragmented manner. However, we do not know how more complex Episodic, Event-based memories are forgotten. We assessed both retrieval accuracy and dependency-the statistical association between the retrieval successes of different elements from the same Event-for complex Events. Across 4 experiments, we show that retrieval dependency is found both immediately after learning and following a 12-hr and 1-week delay. Further, the amount of retrieval dependency after a delay is greater than that predicted by a model of independent forgetting. This dependency was only seen for coherent "closed-loops," where all pairwise associations between locations, people, and objects were encoded. When "open-loops" were learned, where only 2 out of the 3 possible associations were encoded, no dependency was seen immediately after learning or after a delay. Finally, we also provide evidence for higher retention rates for closed-loops than for open-loops. Therefore, closed-loops do not fragment as a function of forgetting and are retained for longer than are open-loops. Our findings suggest that coherent Episodic Events are not only retrieved, but also forgotten, in an all-or-none manner. (PsycINFO Database Record (c) 2020 APA, all rights reserved).
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United we fall: All-or-none forgetting of complex Episodic Events
2018Co-Authors: Bardur Hofgaard Joensen, M. Gareth Gaskell, Aidan J. HornerAbstract:Do complex Event representations fragment over time or are they, instead, forgotten in an all-or-none manner? For example, if we met a friend in a café and they gave us a present, do we forget the constituent elements of this Event (location, person and object) independently, or would the whole Event be forgotten as one? Research suggests that item-based memories are forgotten in a fragmented manner. However, we do not know how more complex Episodic, ‘Event-based’ memories are forgotten. We assessed both retrieval accuracy and dependency – the statistical association between the retrieval successes of different elements from the same Event – for complex Events. Across 4 experiments, we show that retrieval dependency is found both immediately after learning and following a 12-hour and 1-week delay. Further, the amount of retrieval dependency after a delay is greater than that predicted by a model of independent forgetting. This dependency was only seen for coherent ‘closed-loops’, where all pairwise associations between locations, people and objects were encoded. When ‘open-loops’ were learnt, where only two out of the three possible associations were encoded, no dependency was seen immediately after learning nor after a delay. Finally, we also provide evidence for higher retention rates for closed-loops than open-loops. Therefore, closed-loops do not fragment as a function of forgetting, and are retained for longer than open-loops. Our findings suggest that coherent Episodic Events are not only retrieved, but also forgotten, in an all-or-none manner.
Dorthe Berntsen - One of the best experts on this subject based on the ideXlab platform.
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Deficits in remembering the past and imagining the future in patients with prefrontal lesions.
Journal of Neuropsychology, 2016Co-Authors: Katrine W. Rasmussen, Dorthe BerntsenAbstract:Objective Neuroimaging studies suggest that remembering the past and imagining the future engage a common brain network including several areas of the prefrontal cortex. Although patients with prefrontal damage often are described as blind to the future consequences of their decisions, and inclined to ‘live in the here and now’, little is known as to how the prefrontal cortex mediates past and future mental time travel. Method Nine patients with prefrontal lesions and nine healthy controls generated past and future Events in response to different time periods. Event transcriptions were scored using the Autobiographical Interview protocol (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002), which provides a reliable system for categorizing internal (Episodic) and external (semantic) information. For each Event, participants answered a series of questions to assess self-reported phenomenal characteristics. Results Patients with prefrontal lesions exhibited deficits in both remembering past Events and imagining future Events by generating fewer internal details than controls. This effect of group was larger in the past condition than in the future condition. In contrast, no group differences were seen in the number of external details, which were at the same level for patients and controls for both temporal conditions. There were no group differences in ratings of phenomenal characteristics. Conclusion Our findings suggest that damage to prefrontal structures adversely affects the retrieval of past and the construction of future Events. In particular, prefrontal structures are critical for the production of Episodic Event-specific details when engaging in past and future mental time travel.
Agathe Roubertie - One of the best experts on this subject based on the ideXlab platform.
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Cognitive impairment in children with CACNA 1A mutations
Developmental Medicine and Child Neurology, 2020Co-Authors: Veronique Humbertclaude, Benjamin Krams, Nicolas Nagot, Florence Riant, Agathe Roubertie, Valérie Zimmermann, Daniel Annequin, Bernard Echenne, Elisabeth Tournier-lasserve, Chrystelle BonnemainsAbstract:Aim: To describe the clinico‐radiological phenotype of children with a CACNA 1A mutation and to precisely evaluate their learning ability and cognitive status. Method: Children between the ages of 3 and 18 years harboring a pathogenic CACNA 1A mutation associated with Episodic ataxia, hemiplegic migraine, benign paroxysmal torticollis, benign paroxysmal vertigo, or benign paroxysmal tonic upgaze, were enrolled in this cross‐sectional study. Data concerning psychomotor development, academic performance, educational management, clinical examination at inclusion, and brain imaging were collected. Cognitive assessment was performed using age‐standardized scales. Results: Eighteen patients (nine males, nine females; mean age at inclusion: 11y 7mo [SD 4y 5mo; range 3y–17y 11mo]) from 14 families were enrolled. Eleven patients displayed the coexistence or consecutive occurrence of more than one type of Episodic Event. Nine patients exhibited abnormal neurological examination at inclusion. Brain magnetic resonance imaging (MRI ) showed cerebellar atrophy in five patients. Psychomotor development was delayed in nine patients and academic difficulties were reported by the parents in 15 patients; nine patients were in special education. Impairment of intellectual function was assessed in six of the 12 patients with interpretable Full‐scale IQ scores and was more frequent when cerebellar atrophy was present on MRI . Interpretation: Cognitive impairment is commonly associated with CACNA 1A mutations. We suggest that CACNA 1A ‐associated phenotype should be considered a neurodevelopmental disorder.
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Cognitive impairment in children with CACNA1A mutations
Developmental medicine and child neurology, 2019Co-Authors: Veronique Humbertclaude, Benjamin Krams, Nicolas Nagot, Florence Riant, Valérie Zimmermann, Daniel Annequin, Bernard Echenne, Elisabeth Tournier-lasserve, Agathe RoubertieAbstract:Aim To describe the clinico-radiological phenotype of children with a CACNA1A mutation and to precisely evaluate their learning ability and cognitive status. Method Children between the ages of 3 and 18 years harboring a pathogenic CACNA1A mutation associated with Episodic ataxia, hemiplegic migraine, benign paroxysmal torticollis, benign paroxysmal vertigo, or benign paroxysmal tonic upgaze, were enrolled in this cross-sectional study. Data concerning psychomotor development, academic performance, educational management, clinical examination at inclusion, and brain imaging were collected. Cognitive assessment was performed using age-standardized scales. Results Eighteen patients (nine males, nine females; mean age at inclusion: 11y 7mo [SD 4y 5mo; range 3y-17y 11mo]) from 14 families were enrolled. Eleven patients displayed the coexistence or consecutive occurrence of more than one type of Episodic Event. Nine patients exhibited abnormal neurological examination at inclusion. Brain magnetic resonance imaging (MRI) showed cerebellar atrophy in five patients. Psychomotor development was delayed in nine patients and academic difficulties were reported by the parents in 15 patients; nine patients were in special education. Impairment of intellectual function was assessed in six of the 12 patients with interpretable Full-scale IQ scores and was more frequent when cerebellar atrophy was present on MRI. Interpretation Cognitive impairment is commonly associated with CACNA1A mutations. We suggest that CACNA1A-associated phenotype should be considered a neurodevelopmental disorder. What this paper adds Cognitive disabilities and academic difficulties are common in children with CACNA1A mutations associated with Episodic syndromes. Cognitive function ranges from normal to moderate intellectual disorder in wheelchair-dependent children. Patients with vermian atrophy are at a higher risk of cognitive impairment.