Validating EEG, MEG and Combined MEG and EEG Beamforming for an Estimation of the Epileptogenic Zone in Focal Cortical Dysplasia

MEG and EEG source analysis is frequently used for the presurgical evaluation of pharmacoresistant epilepsy patients. The source localization of the epileptogenic zone depends, among other aspects, on the selected inverse and forward approaches and their respective parameter choices. In this validation study, we compare the standard dipole scanning method with two beamformer approaches for the inverse problem, and we investigate the influence of the covariance estimation method and the strength of regularization on the localization performance for EEG, MEG, and combined EEG and MEG. For forward modelling, we investigate the difference between calibrated six-compartment and standard three-compartment head modelling. In a retrospective study, two patients with focal epilepsy due to focal cortical dysplasia type IIb and seizure freedom following lesionectomy or radiofrequency-guided thermocoagulation (RFTC) used the distance of the localization of interictal epileptic spikes to the resection cavity resp. RFTC lesion as reference for good localization. We found that beamformer localization can be sensitive to the choice of the regularization parameter, which has to be individually optimized. Estimation of the covariance matrix with averaged spike data yielded more robust results across the modalities. MEG was the dominant modality and provided a good localization in one case, while it was EEG for the other. When combining the modalities, the good results of the dominant modality were mostly not spoiled by the weaker modality. For appropriate regularization parameter choices, the beamformer localized better than the standard dipole scan. Compared to the importance of an appropriate regularization, the sensitivity of the localization to the head modelling was smaller, due to similar skull conductivity modelling and the fixed source space without orientation constraint.

Open-Source Analysis of Submerged Aquatic Vegetation Cover in Complex Waters Using High-Resolution Satellite Remote Sensing: An Adaptable Framework

Despite being recognized as a key component of shallow-water ecosystems, submerged aquatic vegetation (SAV) remains difficult to monitor over large spatial scales. Because of SAV’s structuring capabilities, high-resolution monitoring of submerged landscapes could generate highly valuable ecological data. Until now, high-resolution remote sensing of SAV has been largely limited to applications within costly image analysis software. In this paper, we propose an example of an adaptable open-sourced object-based image analysis (OBIA) workflow to generate SAV cover maps in complex aquatic environments. Using the R software, QGIS and Orfeo Toolbox, we apply radiometric calibration, atmospheric correction, a de-striping correction, and a hierarchical iterative OBIA random forest classification to generate SAV cover maps based on raw DigitalGlobe multispectral imagery. The workflow is applied to images taken over two spatially complex fluvial lakes in Quebec, Canada, using Quickbird-02 and Worldview-03 satellites. Classification performance based on training sets reveals conservative SAV cover estimates with less than 10% error across all classes except for lower SAV growth forms in the most turbid waters. In light of these results, we conclude that it is possible to monitor SAV distribution using high-resolution remote sensing within an open-sourced environment with a flexible and functional workflow.

Source apportionment and health risk assessment of indoor volatile organic compounds

In extremely cold areas with long winter months and exceptionally cold weather, classrooms are inadequately ventilated, resulting in the continuous accumulation of indoor air pollutants that may endanger human health. This article uses adsorption tube sampling-thermal desorption-gas chromatography mass spectrometry to analyze the type and concentration of volatile organic compounds (VOCs) in the classroom. The source analysis and health risk assessment were performed, and the real-time concentration of total volatile organic compounds (TVOC) was computed using the multifunctional ventilation. The result shows that the air in the classroom contains 25 kinds of VOCs. Among them, the carcinogenic risk value of seven kinds of VOCs (3.40 × 10-5) exceeds the acceptable risk value (1 × 10-6) given by the U.S. Environmental Protection Agency (US EPA). There are 17 kinds of VOCs that pose a certain non-carcinogenic risk to the human body. After quantitative analysis by the principal component analysis (PCA) and the characteristic quantity concentration ratio method, human activities, furnishings, outdoor penetration, etc., were found to be main sources of VOCs in the classroom. In addition, TVOC concentration is directly proportional to class time. In winter, classrooms in severely cold areas must take necessary measures to reduce the concentration of VOCs and ensure students' health.

Simulation of the Multi-Timescale Stratospheric Intrusion Processes in a Typical Cut-Off Low over Northeast Asia

This study used the FLEXPART-WRF trajectory model to perform forward and backward simulations of a cut-off low (COL) event over northeast Asia. The analysis reveals the detailed trajectories and sources of air masses within the COL. Their trajectories illustrate the multi-timescale deep intrusion processes in the upper troposphere and lower stratosphere (UTLS) caused by the COL. The processes of air intrusion from the lower stratosphere to the middle troposphere can be divided into three stages: a slow descent stage, a rapid intrusion stage and a relatively slow intrusion stage. A source analysis of targeted air masses at 300 hPa and 500 hPa shows that the ozone-rich air in the COL primarily originated from an extratropical cyclone over central Siberia and from the extratropical jet stream. The sources of air masses in different parts of the COL show some differences. These results can help explain the ozone distribution characteristics in the main body of a COL at 300 hPa and at 500 hPa that were revealed in a previous study.

Pathogenesis and methods of diagnosis of chronic kidney disease in cats: retrospective analysis (1981–2007)

The aim: to conduct a retrospective analysis of literature sources on the pathogenesis and methods of diagnosis of chronic kidney disease in cats. Materials and methods. The research was conducted by the method of scientific literature open-source analysis: PubMed, Elsevier, electronic resources of the National Library named after V.I. Vernadsky (1981–2007). Results. Chronic kidney disease is a common reason for cat owners to go to veterinary clinics. The term “chronic kidney disease” has a broader meaning than the more limited and not very specific name – chronic renal failure; it is also used to indicate the preazotemic stage of the disease. Chronic kidney disease is characterized by a gradual deterioration of the clinical condition of animals due to progressive decline in renal function. An idea of the pathogenesis and methods of diagnosis of chronic kidney disease in the period from 1981 to 2007 is presented. Conclusions. According to the results of retrospective analysis of literature sources for the period from 1981 to 2007, the basis was identified aspects of the pathogenesis of chronic kidney disease in domestic cats, which have not lost relevance today. The main link during chronic kidney disease in cats is the development of hyperazotemia and, as a consequence, endogenous intoxication of the body, which develops gradually and leads to the death of the animal. The morphological basis of chronic kidney disease in cats is the development of diffuse nephrosclerosis, which is reflected in the results of clinical, biochemical and instrumental studies. According to biochemical analysis of blood, in cats recorded an increase in urea and creatinine, the results of clinical studies of urine showed a decrease in its relative density, as well as the development of proteinuria, the appearance of erythrocytes and cylinders. According to the results of hematological research, anemic syndrome develops due to decreased erythropoietin synthesis. With age in cats, ultrasound examination of the kidneys reveals a decrease in their volume due to uniform sclerosis of the parenchyma: it is determined by its thinning and increased echogenicity due to the accumulation of connective tissue components, which is a sign of nephrosclerosis. Although kidney biopsy is the most informative method of diagnosing chronic kidney disease, it has many contraindications, which does not allow its use in the routine diagnosis of nephropathy in domestic cats. its thinning and increase in echogenicity due to the accumulation of connective tissue components, which is a sign of nephrosclerosis, is determined. Although kidney biopsy is the most informative method of diagnosing chronic kidney disease, it has many contraindications, which does not allow its use in the routine diagnosis of nephropathy in domestic cats. Its thinning and increase in echogenicity due to the accumulation of connective tissue components, which is a sign of nephrosclerosis, is determined