Which reference is appropriate for the scalp ERP and EEG studies? This unsettled problem still inspires unceasing debate. The ideal reference should be the one with zero or constant potential but ...unfortunately it is well known that no point on the body fulfills this condition. Consequently, more than ten references are used in the present EEG-ERP studies. This diversity seriously undermines the reproducibility and comparability of results across laboratories. A comprehensive review accompanied by a brief communication with rigorous derivations and notable properties (Hu et al. Brain Topogr,
2019
.
https://doi.org/10.1007/s10548-019-00706-y
) is thus necessary to provide application-oriented principled recommendations. In this paper current popular references are classified into two categories: (1) unipolar references that construct a neutral reference, including both online unipolar references and offline re-references. Examples of unipolar references are the reference electrode standardization technique (REST), average reference (AR), and linked-mastoids/ears reference (LM); (2) non-unipolar references that include the bipolar reference and the Laplacian reference. We show that each reference is derived with a different assumption and serves different aims. We also note from (Hu et al.
2019
) that there is a general form for the reference problem, the ‘no memory’ property of the unipolar references, and a unified estimator for the potentials at infinity termed as the regularized REST (rREST) which has more advantageous statistical evidence than AR. A thorough discussion of the advantages and limitations of references is provided with recommendations in the hope to clarify the role of each reference in the ERP and EEG practice.
Die Art und Weise, wie die Menschen über das alltägliche und zugleich so komplexe Wetter nachdenken, hat eine überraschende Geschichte. Bevor die Meteorologie um 1850 eine Physik der Atmosphäre ...wurde, gab es verschiedene Formen des Wetterwissens: eine, die nach Naturgesetzen forschte, aber auch eine, die Wetterzeichen sammelte und eine, die das Wetter als Teil eines natürlichen Organismus untersuchte. Diesen verschiedenen historischen Wissensformen und ihren Akteuren geht die vorliegende Studie auf den Grund. Untersucht wird, wie sich die moderne Meteorologie aus ihnen entwickelte – und auch, welches Wissen dabei verlorenging.
creativecommons.org/licenses/by-nc-nd/4.0/deed.de
A 1 nA current reference circuit is designed in semiconductor laboratory (SCL) 0.18 μm standard threshold voltage CMOS technology under 1.8 V power supply. The reference current is extremely immune ...to supply variation and shows a line sensitivity of 0.002%/V at post layout simulation level, over a wide range of supply variation from 0.5 V to 3.5 V. The line sensitivity is much smaller than any relevant data so far reported. In addition, it has a very low temperature coefficient of 214 ppm/°C over a temperature variation from −50°C to 50°C. The circuit consumes a total power of 588 nW. The reported results are also studied at various process corners and under variable process parameters like oxide thickness and threshold voltage of transistors. A satisfactory behaviour of the circuit is obtained in all cases. The accuracy of the simulation results is validated through quite close matching of the results with that obtained through rigorously developed theoretical models.
Background
Biological variation helps determine whether population‐based or subject‐based reference intervals are more appropriate to assess changes in serial analytical values. Previous studies have ...investigated the biological variation of biochemical analytes weekly or with variable frequency over 5‐14 weeks in cats, but none have considered biological variation at less frequent intervals over 1 year.
Objectives
We aimed to evaluate the long‐term biological variation of 19 biochemical analytes in clinically healthy cats.
Methods
A prospective, observational study in which 15 clinically healthy, client‐owned cats were sampled for serum biochemical analyses every 8 weeks for 1 year. Frozen serum samples were single‐batch analyzed. Restricted maximum likelihood estimation was used to determine the coefficients of variation (CV), describing variation within each cat, between cats, and the analytical variation. These CVs were used to determine the indices of individuality and reference change values (RCVs).
Results
Albumin, alkaline phosphatase, creatine kinase, and globulin had high indices of individuality, indicating that they are best evaluated by RCVs. Phosphorus, potassium, chloride, sodium, symmetric dimethylarginine, and total CO2 had low indices of individuality, indicating that population‐based reference intervals are appropriate. Alanine aminotransferase, aspartate aminotransferase, blood urea nitrogen, calcium, cholesterol, creatinine, glucose, total bilirubin, and total protein had intermediate indices of individuality, indicating that RCVs may provide additional insight into the interpretation of analyte measurements beyond the population‐based reference intervals.
Conclusions
For many analytes, the biological variation detected was similar to that reported in prior studies. Clinicians should consider the biological variation of analytes to best interpret clinically relevant changes in serial analyte measurements.
Chat reference has been a popular form of synchronous virtual reference used by academic libraries. Since the COVID-19 pandemic, many academic law libraries have also adopted this tool to provide ...reference services remotely. This article examines the current usage of chat reference among academic law libraries through a survey of law library websites of all ABA-Accredited law schools. The author discusses the advantages of using chat reference, the staffing issue, and possible solutions to that. The author suggests the usage of chatbot to extend reference hours and create a more interactive and welcoming atmosphere to library website users.
As the lipidomics field continues to advance, self-evaluation within the community is critical. Here, we performed an interlaboratory comparison exercise for lipidomics using Standard Reference ...Material (SRM) 1950–Metabolites in Frozen Human Plasma, a commercially available reference material. The interlaboratory study comprised 31 diverse laboratories, with each laboratory using a different lipidomics workflow. A total of 1,527 unique lipids were measured across all laboratories and consensus location estimates and associated uncertainties were determined for 339 of these lipids measured at the sum composition level by five or more participating laboratories. These evaluated lipids detected in SRM 1950 serve as community-wide benchmarks for intra- and interlaboratory quality control and method validation. These analyses were performed using nonstandardized laboratory-independent workflows. The consensus locations were also compared with a previous examination of SRM 1950 by the LIPID MAPS consortium. While the central theme of the interlaboratory study was to provide values to help harmonize lipids, lipid mediators, and precursor measurements across the community, it was also initiated to stimulate a discussion regarding areas in need of improvement.
Biological variation (BV) data have many applications in laboratory medicine. However, these depend on the availability of relevant and robust BV data fit for purpose. BV data can be obtained through ...different study designs, both by experimental studies and studies utilizing previously analysed routine results derived from laboratory databases. The different BV applications include using BV data for setting analytical performance specifications, to calculate reference change values, to define the index of individuality and to establish personalized reference intervals. In this review, major achievements in the area of BV from last decade will be presented and discussed. These range from new models and approaches to derive BV data, the delivery of high-quality BV data by the highly powered European Biological Variation Study (EuBIVAS), the Biological Variation Data Critical Appraisal Checklist (BIVAC) and other standards for deriving and reporting BV data, the EFLM Biological Variation Database and new applications of BV data including personalized reference intervals and measurement uncertainty.
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