Mercury anomalies associated with three extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) in NW Pangea

Copyright © Cambridge University Press 2015. Strata of Permian - Early Triassic age that include a record of three major extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) were examined at the Festningen section, Spitsbergen. Over the c. 12 Ma record examined, mercury in the sediments shows relatively constant background values of 0.005-0.010 μg g -1 . However, there are notable spikes in Hg concentration over an order of magnitude above background associated with the three extinctions. The Hg/total organic carbon (TOC) ratio shows similar large spikes, indicating that they represent a true increase in Hg loading to the environment. We argue that these represent Hg loading events associated with enhanced Hg emissions from large igneous province (LIP) events that are synchronous with the extinctions. The Hg anomalies are consistent across the NW margin of Pangea, indicating that widespread mercury loading occurred. While this provides utility as a chemostratigraphic marker the Hg spikes may also indicate loading of toxic metals to the environment, a contributing cause to the mass extinction events

Univariate and Multivariate Generalized Multiscale Entropy to Characterise EEG Signals in Alzheimer’s Disease

Alzheimer’s disease (AD) is a degenerative brain disorder leading to memory loss and changes in other cognitive abilities. The complexity of electroencephalogram (EEG) signals may help to characterise AD. To this end, we propose an extension of multiscale entropy based on variance (MSEσ2) to multichannel signals, termed multivariate MSEσ2 (mvMSEσ2), to take into account both the spatial and time domains of time series. Then, we investigate the mvMSEσ2 of EEGs at different frequency bands, including the broadband signals filtered between 1 and 40Hz, θ, α, and β bands, and compare it with the previously proposed multiscale entropy based on mean (MSEµ), multivariate MSEµ (mvMSEµ), and MSEσ2, to distinguish different kinds of dynamical properties of spread and mean in the signals. Results from 11 AD patients and 11 age-matched controls suggest that the presence of broadband activity of EEGs is required for a proper evaluation of complexity. MSEσ2 and mvMSEσ2 results, showing a loss of complexity in AD signals, led to smaller p-values in comparison with MSEµ and mvMSEµ ones, suggesting that the variance-based MSE and mvMSE can characterise changes in EEGs as a result of AD in a more detailed way. The p-values for the slope values of mvMSE curves were smaller than for MSE at large scale factors, also showing the possible usefulness of multivariate techniques

A possible phytosaurian (Archosauria, pseudosuchia) coprolite from the late triassic fleming fjord group of jameson land, central east Greenland

Funding Information: This project is part of a combined sedimentological, palaeontological and magnetostratigraphical investigation of the Late Triassic vertebrate-bearing continental deposits in central East Greenland supported by the Independent Research Fund Denmark. We thank Dennis V. Kent for productive discussions on Late Triassic stratigraphy. We are grateful to Karen Dybkjær, GEUS, for help with palynological examination of the coprolite. We thank Bo Markussen, Department of Mathematical Sciences at the University of Copenhagen, for guidance about statistical analyses. We gratefully acknowledge support from Dronning Margrethes og Prins Henriks Fond, Arbejdsmarkedets Feriefond, Oticon Fonden, Knud Højgaards Fond, Louis Petersens Legat, Det Obelske Familiefond, Ernst og Vibeke Husmans Fond, the Carlsberg Foundation and Geocenter Møns Klint. GEUS provided valuable logistical support. We thank Adrian Hunt and an anonymous referee for constructive reviews.A large, well-preserved vertebrate coprolite was found in a lacustrine sediment in the Malmros Klint Formation of the Late Triassic Fleming Fjord Group in the Jameson Land Basin, central East Greenland. The size and internal and external morphology of the coprolite is consistent with that of crocodilian coprolites and one end of the coprolite exhibits evidence of post-egestion trampling. As the associated vertebrate fauna of the Fleming Fjord Group contains abundant remains of pseudosuchian phytosaurs, the coprolite is interpreted as being from a large phytosaur.publishersversionpublishe

A Time-Frequency approach for EEG signal segmentation

The record of human brain neural activities, namely electroencephalogram (EEG), is generally known as a non-stationary and nonlinear signal. In many applications, it is useful to divide the EEGs into segments within which the signals can be considered stationary. Combination of empirical mode decomposition (EMD) and Hilbert transform, called Hilbert-Huang transform (HHT), is a new and powerful tool in signal processing. Unlike traditional time-frequency approaches, HHT exploits the nonlinearity of the medium and non-stationarity of the EEG signals. In addition, we use singular spectrum analysis (SSA) in the pre-processing step as an effective noise removal approach. By using synthetic and real EEG signals, the proposed method is compared with wavelet generalized likelihood ratio (WGLR) as a well-known signal segmentation method. The simulation results indicate the performance superiority of the proposed method

Diagnosis Performance of Cerebral Venous Thrombosis with Magnetic Resonance Imaging and Magnetic Resonance Venography in Zahedan (Southeast of Iran): A Series of 57 Patients

BACKGROUND: Cerebral venous sinus thrombosis (CVST) is a scarce disease with poor prognosis and its diagnosis often challenges physicians due to nonspecific symptoms and widespread clinical manifestations. AIM: To investigate the findings of magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) of patients with CVST diagnosis in Ali Ebne Abitaleb Hospital in Zahedan during 2013–2016 and to evaluate imaging pitfalls involving in late diagnosis, complications, and even death. METHODS: This retrospective descriptive study was done on 57 patients with confirmed CVST during 2013–2016 in Ali Ebne Abitaleb Hospital in Southeast of Iran (Zahedan). The MRI and MRV findings and related diagnostic pitfalls were evaluated. Twenty-one patients are pediatrics and 33 patients are adults. RESULTS: Of 57 patients, evidences of cerebral edema were found in 33 patients, among whom 2 patients showed parenchymal edema (cerebral edema) without infarction, and 31 patients exhibited parenchymal edema with infarction. The frequency of involvement in descending order was as followed; transverse sinus (96.49%), sigmoid sinus (49.12%), superior sagittal sinus (29.82%), jugular vein (19.29%), internal cerebral veins (7.01%), straight sinus (5.2%), and cortical veins (5.2%). Diagnostic pitfalls were also found in 8 patients. Seven patients exhibited acute and subacute thrombosis mimicked normal sinus flow void in T2-weighted images. No filling defect was seen on gadolinium-enhanced T1-weighted image in the other patient due to the sub-acute phase of thrombosis. CONCLUSION: The delayed diagnosis of CVST originating from nonspecific clinical features and diagnostic imaging pitfalls can result in poor outcomes in patients. To prevent the diagnostic pitfalls, the clinician should give a brief history and clinical data and radiologist(s) should interpret the findings in addition to the use of advanced MR sequences

Triassic-Jurassic vegetation response to carbon cycle perturbations and climate change

Disturbances in terrestrial vegetation across the end-Triassic mass-extinction (ETME) and earliest Jurassic (∼201.5–201.3 Ma) have previously been linked to carbon cycle perturbations induced by the Central Atlantic Magmatic Province. Large-scale volcanic degassing has been proposed to have affected the terrestrial realm through various mechanisms. However, the effects of long-term “super greenhouse” climate variability on vegetation dynamics following the mass-extinction remain poorly understood. Based on a 10-million-year long multi-proxy record of northern Germany (Schandelah-1, Germany, paleolatitude of ∼41°N) spanning the late Rhaetian to the Sinemurian (∼201.5–190.8 Ma), we aim to assess mechanistic links between carbon cycle perturbations, climate change, and vegetation dynamics. Based on a high-resolution palynofloral record a two-phased extinction emerges, confirming extinction patterns seen in other studies. The first phase is associated with a decline in arborescent conifers, coinciding with a negative carbon isotope excursion and an influx of aquatic palynomorphs. Following this decline, we find a stepwise rise of ferns at the cost of trees during the latest Rhaetian, culminating with the extinction of tree taxa at the Triassic-Jurassic boundary. The rise in ferns is accompanied by an increase in reworked organic matter and charcoal, suggestive of erosion and wildfires. Furthermore, the Hettangian (201.3–199.3 Ma) vegetation in NW Europe shows evidence of long-term disturbance reflected by the periodic resurgence of fern taxa, similarly accompanied by increases in reworking and charcoal. This periodicity is linked to the 405-kyr eccentricity cycle indicating a biome that responded to astronomically induced variability in hydrology. A transition into an apparently more stable biome starts during the early Sinemurian, where palynofloral assemblages become dominated by bisaccate pollen taxa, mainly derived from conifers. The ETME was clearly forced by the effects of volcanogenic emissions, such as SO2, CO2 and other pollutants, acting on both short (0.1–10 kyrs) and long timescales (10–100 kyrs). In contrast, charcoal and detrital input indicators show that the disturbances during the Hettangian were driven by periodic shifts in the regional hydrological regime. This was forced by the effects of orbital insolation variation and potentially exacerbated by increased atmospheric pCO2. The cyclic progression of ecosystem disturbance was similar to that of the ETME and only recovered during the early Sinemurian. Atmospheric pCO2 remained elevated after CAMP-activity had subsided due to a collapse of terrestrial biomass and carbonate producers. This inability to store carbon on long timescales could therefore have impeded global recovery

Predicting the valence of a scene from observers’ eye movements

Multimedia analysis benefits from understanding the emotional content of a scene in a variety of tasks such as video genre classification and content-based image retrieval. Recently, there has been an increasing interest in applying human bio-signals, particularly eye movements, to recognize the emotional gist of a scene such as its valence. In order to determine the emotional category of images using eye movements, the existing methods often learn a classifier using several features that are extracted from eye movements. Although it has been shown that eye movement is potentially useful for recognition of scene valence, the contribution of each feature is not well-studied. To address the issue, we study the contribution of features extracted from eye movements in the classification of images into pleasant, neutral, and unpleasant categories. We assess ten features and their fusion. The features are histogram of saccade orientation, histogram of saccade slope, histogram of saccade length, histogram of saccade duration, histogram of saccade velocity, histogram of fixation duration, fixation histogram, top-ten salient coordinates, and saliency map. We utilize machine learning approach to analyze the performance of features by learning a support vector machine and exploiting various feature fusion schemes. The experiments reveal that ‘saliency map’, ‘fixation histogram’, ‘histogram of fixation duration’, and ‘histogram of saccade slope’ are the most contributing features. The selected features signify the influence of fixation information and angular behavior of eye movements in the recognition of the valence of images