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  • 1
    Publication Date: 2024-04-05
    Description: In the last decade, sleep spindles have attracted steadily increasing attention. This interest is motivated by the many intriguing relationships between spindles and various diseases (e.g., schizophrenia, Parkinson, Alzheimer, autism, mental retardation), recovery processes (e.g., post brain stroke), and cognitive faculties (e.g., memory consolidation, intelligence, dream recall, sleep preservation). Nonetheless, a methodological wall has impeded the study of sleep spindles. Their investigation rests heavily on our ability to reliably and consistently identify spindle patterns from background EEG activity, a task involving many obstacles, including: a fuzzy definition of spindles, low inter-expert agreement on their scoring, lack of consensus on standard techniques for their automated detection, low reproducibility of observed characteristics and correlates, unavailability of large, standardized, high-quality databases, and inconsistencies in the methods used to evaluate the performance of automated detectors. The primary aims of this research topic were to bring together world-class researchers on a project designed to facilitate exchanges on methodological difficulties encountered in assessing sleep spindles and to promote standardized spindle-related resources. In preparing their contributions, authors were encouraged to use existing – or to propose new – publicly available resources for assessing sleep spindles. To allow fair and accurate comparison of reported results, the authors were also encouraged to validate their tools on a common benchmark. A database containing expert spindle scoring (i.e., the Montreal Archive of Sleep Studies) was made publicly available for that purpose.
    Keywords: RC321-571 ; Q1-390 ; Neural oscillations ; Electroencephalography (EEG) ; Sleep ; Sleep Spindles ; Memory ; IQ ; sigma waves ; automatic detection ; biomarker ; Open access ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Language: English
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  • 2
    Publication Date: 2024-04-05
    Description: In the study of sensorimotor systems, an important research goal has been to understand the way neural networks in the spinal cord and brain interact to control voluntary movement. Computational modeling has provided insight into the interaction between centrally generated commands, proprioceptive feedback signals and the biomechanical responses of the moving body. Research in this field is also driven by the need to improve and optimize rehabilitation after nervous system injury and to devise biomimetic methods of control in robotic devices. This research topic is focused on efforts dedicated to identify and model the neuromechanical control of movement. Neural networks in the brain and spinal cord are known to generate patterned activity that mediates coordinated activation of multiple muscles in both rhythmic and discrete movements, e.g. locomotion and reaching. Commands descending from the higher centres in the CNS modulate the activity of spinal networks, which control movement on the basis of sensory feedback of various types, including that from proprioceptive afferents. The computational models will continue to shed light on the central strategies and mechanisms of sensorimotor control and learning. This research topic demonstrated that computational modeling is playing a more and more prominent role in the studies of postural and movement control. With increasing ability to gather data from all levels of the neuromechanical sensorimotor systems, there is a compelling need for novel, creative modeling of new and existing data sets, because the more systematic means to extract knowledge and insights about neural computations of sensorimotor systems from these data is through computational modeling. While models should be based on experimental data and validated with experimental evidence, they should also be flexible to provide a conceptual framework for unifying diverse data sets, to generate new insights of neural mechanisms, to integrate new data sets into the general framework, to validate or refute hypotheses and to suggest new testable hypotheses for future experimental investigation. It is thus expected that neural and computational modeling of the sensorimotor system should create new opportunities for experimentalists and modelers to collaborate in a joint endeavor to advance our understanding of the neural mechanisms for postural and movement control. The editors would like to thank Professor Arthur Prochazka, who helped initially to set up this research topic, and all authors who contributed their articles to this research topic. Our appreciation also goes to the reviewers, who volunteered their time and effort to help achieve the goal of this research topic. We would also like to thank the staff members of editorial office of Frontiers in Computational Neuroscience for their expertise in the process of manuscript handling, publishing, and in bringing this ebook to the readers. The support from the Editor-in-Chief, Dr. Misha Tsodyks and Dr. Si Wu is crucial for this research topic to come to a successful conclusion. We are indebted to Dr. Si Li and Ms. Ting Xu, whose assistant is important for this ebook to become a reality. Finally, this work is supported in part by grants to Dr. Ning Lan from the Ministry of Science and Technology of China (2011CB013304), the Natural Science Foundation of China (No. 81271684, No. 61361160415, No. 81630050), and the Interdisciplinary Research Grant cross Engineering and Medicine by Shanghai Jiao Tong University (YG20148D09). Dr. Vincent Cheung is supported by startup funds from the Faculty of Medicine of The Chinese University of Hong Kong. Guest Associate Editors Ning Lan, Vincent Cheung, and Simon Gandevia
    Keywords: RC321-571 ; Q1-390 ; Postures ; neural circuits ; Sensorimotor control ; movements ; computational modeling ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Language: English
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  • 3
    Publication Date: 2023-12-18
    Description: Core samples recovered from the Transkei Basin (Hole U1581B), offshore South Africa, during IODP Expedition 392 include an expansive record of organic-rich sediments from the Campanian to Paleocene (~74-63 Ma). Investigation of the biomarker composition of this sequence revealed significant amounts of polycyclic aromatic hydrocarbons (PAH) reflecting terrestrial sources of organic matter (OM) coupled with evidence for wildfires. Perylene, derived from diagenetic alteration of terrestrial OM, is the dominant PAH in the Campanian sediments. Other prominent PAH components are tetrahydrochysenes and tetrahydropicenes, which are formed by early-stage diagenetic aromatization, with or without loss of the functionalized A-ring, of triterpenoid lipids. The co-occurrence of their precursor alkenes and ketones afforded further evidence for inputs of angiosperm-derived terrigenous OM, whereas the absence of diterpenoids suggests minimal contributions of terrestrial OM from gymnosperms. The dominance of OM originating from angiosperms throughout this interval suggests that these plants were well-established as the principal vegetation in southern Africa following their expansion during the Late Cretaceous. The presence of coronene in the sedimentary succession indicates that the sources of terrestrial OM also include pyrogenic material because this compound is formed during intense combustion and therefore serves as a sedimentary marker for wildfires. Coronene occurs as a minor PAH component in Campanian samples, but it is a prominent PAH component of the Paleocene samples. It is dominant in the basal Paleocene sample consistent with inputs from global wildfires at the K/Pg boundary, confirming their prevalence at high southern latitudes, whereas the lower proportion of perylene in this interval may reflect a diminished supply of unburnt lignin precursors. Coronene remains a substantive component in later Paleocene samples suggesting the protracted occurrence of wildfires. In addition, PAH generated during the K-Pg boundary event may provide a sustained detrital influx derived from erosion and weathering of burnt biomass, which is consistent with evidence that larger PAH are primarily transported by clastic detritus rather than airborne particulates.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 4
    Publication Date: 2023-12-18
    Description: Campanian to Paleocene organic-rich sediments (~74-60 Ma) recovered from the Transkei Basin (Hole U1581B), offshore South Africa, during IODP Expedition 392 contain suites of C37-C40 alkenones derived from haptophyte algae that extend the temporal continuity of their occurrences and expand their paleogeographic range to high southern latitudes (~58°S) during this time interval. Alkenone profiles are broadly similar throughout the stratigraphic section with the similarity between Maastrichtian and Danian samples indicating a conformity in biosynthetic pathways across the K/Pg boundary. Thus, the source haptophytes for alkenones survived and subsequently recovered after the extinction event, consistent with temporal trends for assemblages of calcareous nannoplankton from the southern hemisphere. The lineages of specific alkenones record evolutionary developments in their biosynthetic pathways. The occurrence of a methyl C39:2 alkenone in the Paleocene and both methyl and ethyl C38 and C39 alkenones in the Campanian extends the range of occurrence of alkenone with carbonyl groups at multiple positions, and the required duality in their biosynthetic pathways. The dominance of the C40 alkadien-3-one in several samples contrasts with its scarcity in Neogene marine sediments and presence among extant haptophytes. C40 alkenones are prevalent constituents of coastal and lacustrine species in phylogenic Group II, notably Isochrysis, but have only once been reported in marine species from phylogenic Group III. The sporadic prominence of C40 alkenones prior to the early Eocene seems to reflect a broader suite of active biosynthetic pathways than those expressed by extant marine haptophytes. Thus, Cretaceous through Paleocene marine sediments may reflect alkenone contributions from both Isochrysidaceae (Group II) and Noelaerhabdaceae (Group III) following their divergence in the Early Cretaceous. The accompanying C40:3 alkenone contrasts with the absence of other alkatrienones prior to the appearance of C37 and C38 components in the Paleocene. These data refute the hypothesis that alkatrienones represent a response in haptophyte producers to ocean cooling after the early Eocene Climatic Optimum (EECO) and suggest this biosynthetic innovation may have originated at high southern latitudes.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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  • 5
    Publication Date: 2023-01-04
    Description: Northern peatlands store 300–600 Pg C, of which approximately half are underlain by permafrost. Climate warming and, in some regions, soil drying from enhanced evaporation are progressively threatening this large carbon stock. Here, we assess future CO2 and CH4 fluxes from northern peatlands using five land surface models that explicitly include representation of peatland processes. Under Representative Concentration Pathways (RCP) 2.6, northern peatlands are projected to remain a net sink of CO2 and climate neutral for the next three centuries. A shift to a net CO2 source and a substantial increase in CH4 emissions are projected under RCP8.5, which could exacerbate global warming by 0.21°C (range, 0.09–0.49°C) by the year 2300. The true warming impact of peatlands might be higher owing to processes not simulated by the models and direct anthropogenic disturbance. Our study highlights the importance of understanding how future warming might trigger high carbon losses from northern peatlands.
    Type: Article , PeerReviewed
    Format: text
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  • 6
    Publication Date: 2021-08-25
    Description: Seismic wave propagation is intrinsically a process in time and space. Although seismometers make point measurements only, dense, large-aperture seismic networks allow the full observation and analysis of wave propagation. We present a new visual representation of teleseismic phases by combining time-dependent ground-motion visualizations with array analyses to connect the time-domain motion with phase information retrieved from the frequency–wavenumber (f-k) domain. This serves as an educational tool, but also for efficient identification of off-angle arrivals, dispersion, and anomalous seismic phases. The processing is applied to events with Mw≥7 observed at the AlpArray Seismic Network in Europe and two example teleseismic events are discussed in detail.
    Print ISSN: 0895-0695
    Electronic ISSN: 1938-2057
    Topics: Geosciences
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  • 7
    Publication Date: 2021-10-29
    Description: Understanding the spatial distribution of metals within galaxies allows us to study the processes of chemical enrichment and mixing in the interstellar medium (ISM). In this work, we map the two-dimensional distribution of metals using a Gaussian Process Regression (GPR) for 19 star-forming galaxies observed with the Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT–MUSE) as part of the PHANGS–MUSE survey. We find that 12 of our 19 galaxies show significant two-dimensional metallicity variation. Those without significant variations typically have fewer metallicity measurements, indicating this is due to the dearth of H ii regions in these galaxies, rather than a lack of higher-order variation. After subtracting a linear radial gradient, we see no enrichment in the spiral arms versus the disc. We measure the 50 per cent correlation scale from the two-point correlation function of these radially-subtracted maps, finding it to typically be an order of magnitude smaller than the fitted GPR kernel scale length. We study the dependence of the two-point correlation scale length with a number of global galaxy properties. We find no relationship between the 50 per cent correlation scale and the overall gas turbulence, in tension with existing theoretical models. We also find more actively star forming galaxies, and earlier type galaxies have a larger 50 per cent correlation scale. The size and stellar mass surface density do not appear to correlate with the 50 per cent correlation scale, indicating that perhaps the evolutionary state of the galaxy and its current star formation activity is the strongest indicator of the homogeneity of the metal distribution.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 8
    Publication Date: 2021-10-13
    Print ISSN: 1530-6984
    Electronic ISSN: 1530-6992
    Topics: Chemistry and Pharmacology , Physics
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