Highlights • A review of technical aspects of transcranial electrical stimulation (tES) techniques. • Recommendations for safe and replicable application of tDCS and other tES methods. • Discussion ...of state-of-the-art methodology and design considerations in tES.
An overview is provided of the geomagnetic storms and impacts on electric power grids associated with the violent Sun‐Earth events of October 2003. During the period from 29 to 31 October 2003, two ...large geomagnetic storms were observed, as measured by periods of high Kp, Ap, and Dst indices. In fact, these storms had Ap rankings of 6th and 16th all time. This ranking would suggest that the October 2003 storms would be significant with regard to geomagnetically induced currents (GIC) in power grids. However, the resulting geomagnetic storms were much lower in delta B and dB/dt intensity than other historically large geomagnetic storms. A variety of geomagnetic storm processes drove observed GIC. For example, ground observations indicated the presence of large dB/dt pulsations and GIC at North American midlatitude locations on 29 October 2003 that may be due to unusually intense Kelvin‐Helmholtz shearing. Sustained disturbance conditions at low‐latitude and equatorial latitude locations that are likely linked to ring current intensifications may be the source of sustained GIC at these locations and the cause of large power transformer failures. Comparative evaluations will be provided for the 29–31 October 2003 storms and other important and contemporary storms, such as those observed on 13–14 March 1989, 13–14 July 1982, and 15–16 July 2001. Rather than an index‐based evaluation method, the comparative evaluations presented in this paper are based on comparisons of storm morphology. This approach provides a more meaningful comparison of geomagnetic field disturbance dynamics that are important to characterize large GIC threats to power grid infrastructures.
The National Grid Company plc (NGC) is the owner and operator of one of the world's largest privatised high-voltage electric power transmission systems in England and Wales at 400 and
275
kV
. As ...owner operator it is responsible for the secure and reliable delivery of electrical energy to all the 25 million electricity supply customers in England and Wales. The transmission and distribution systems in UK have experienced significant effects during past geomagnetic storm events especially during solar cycles 21 and 22. These effects included generator reactive power output swings, voltage dips, negative sequence alarms and transformer failures. Geomagnetically induced current (GIC) monitoring was installed in 1989 and operational procedures were put in place based on global solar weather forecasts. These measures were not capable of delivering reliable information and thus gave many false operational alarms. Their only real use was for post event forensic purposes.
Since the cycle 22 solar peak activity the UK transmission system has developed to become more meshed, heavily loaded and dependent on the availability of reactive compensation equipment for voltage control. NGC carried out GIC impact risk assessment in 1998. This reviewed available options for managing this risk including investigation of blocking measures, a reliable local GIC forecast, GIC monitoring, a review of transmission equipment capabilities to withstand GIC conditions and operational procedures to manage the risk.
As a result of the risk assessment NGC completed installation of a Metatech Spacecast/Powercast space weather forecasting system in May 1999. EPRI Sunburst 2000 based transformer monitoring systems were fully integrated in January 2000 in time for peak solar storm activity in solar cycle 23. This paper will describe the risk analysis undertaken, the risk management processes put in place and the performance of the forecasting and monitoring systems, respectively.
A perspective is provided on design decisions in the electric power grid infrastructure and the formative role this has had in greatly increasing the vulnerability of this critical infrastructure to ...space weather disturbances.
Today's sprawling, high‐voltage power grids are more susceptible to space weather impacts than ever before.
Neuropsychiatric disorders are a leading source of disability and require novel treatments that target mechanisms of disease. As such disorders are thought to result from aberrant neuronal circuit ...activity, neuromodulation approaches are of increasing interest given their potential for manipulating circuits directly. Low intensity transcranial electrical stimulation (tES) with direct currents (transcranial direct current stimulation, tDCS) or alternating currents (transcranial alternating current stimulation, tACS) represent novel, safe, well-tolerated, and relatively inexpensive putative treatment modalities.
This report seeks to promote the science, technology and effective clinical applications of these modalities, identify research challenges, and suggest approaches for addressing these needs in order to achieve rigorous, reproducible findings that can advance clinical treatment.
The National Institute of Mental Health (NIMH) convened a workshop in September 2016 that brought together experts in basic and human neuroscience, electrical stimulation biophysics and devices, and clinical trial methods to examine the physiological mechanisms underlying tDCS/tACS, technologies and technical strategies for optimizing stimulation protocols, and the state of the science with respect to therapeutic applications and trial designs.
Advances in understanding mechanisms, methodological and technological improvements (e.g., electronics, computational models to facilitate proper dosing), and improved clinical trial designs are poised to advance rigorous, reproducible therapeutic applications of these techniques. A number of challenges were identified and meeting participants made recommendations made to address them.
These recommendations align with requirements in NIMH funding opportunity announcements to, among other needs, define dosimetry, demonstrate dose/response relationships, implement rigorous blinded trial designs, employ computational modeling, and demonstrate target engagement when testing stimulation-based interventions for the treatment of mental disorders.
•This NIMH workshop report seeks to promote the science, technology and effective clinical applications of tDCS and tACS.•Knowledge of how tES induces behavioral change in humans is limited. Mechanistic studies aimed at this question are needed.•Improved reporting of protocols and use of computational models to relate dose to current flow in brain will be important.•Predictive biomarkers, target engagement measures, and rigorous study designs are critical for advancing clinical trials.•The above elements align with requirements in NIMH funding opportunity announcements and are important for reproducibility.
Geomagnetic disturbances (i.e., space storms) can impact the operational reliability of transmission systems. Solar Cycle 22 (the most recent solar cycle extending from 1986 to 1996) demonstrated to ...the power industry the need to take into consideration the potential impacts of geomagnetic storms. Experience gained from the unprecedented scale of these recent storm events provides compelling evidence of a general increase in electric power system susceptibility. Important infrastructure advances have recently been put in place that provide solar wind data. This new data source along with numeric model advances allows the capability for predictive forecasts of severe storm conditions, which can be used by impacted power system operators to better prepare for and manage storm impacts.
Contrary to early conceptualizations of emotional experience in schizophrenia (SZ), recent research indicates that patients do not self-report less in-the-moment pleasure than controls (CN). Rather, ...patients report experiencing elevated levels of negative emotionality in response to a range of evocative stimuli. In this study, we examined the possibility that elevations in negative emotionality in SZ may reflect an underlying emotion regulation abnormality. Event-related potentials (ERPs) were recorded from outpatients with SZ (n = 25) and demographically matched healthy controls (n = 21) during passive viewing of unpleasant and neutral photographs. Unpleasant images were preceded by an audio description that described the image as being either negative or neutral. Neutral images were preceded by neutral audio descriptions. The late positive potential (LPP), an ERP component sensitive to cognitive change strategies, was examined as an index of emotion regulation. Both CN and SZ showed an increased LPP to negatively described unpleasant images compared with neutral images. In addition, CN showed evidence of emotion regulation, as reflected by a smaller LPP for unpleasant images preceded by a neutral descriptor, relative to a negative descriptor. In contrast, SZ patients showed an inability to downregulate emotional response, as evidenced by no difference in the amplitude of the LPP for unpleasant images preceded by negative or neutral descriptors. Findings provide neurophysiological evidence for an emotion regulation abnormality in SZ and suggest that failures in cognitive change may underlie increased negative emotionality in SZ.
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by accumulation of amyloid plaques and neurofibrillary tangles in the brain. The major components of plaque, beta-amyloid ...peptides (Abetas), are produced from amyloid precursor protein (APP) by the activity of beta- and gamma-secretases. beta-secretase activity cleaves APP to define the N-terminus of the Abeta1-x peptides and, therefore, has been a long- sought therapeutic target for treatment of AD. The gene encoding a beta-secretase for beta-site APP cleaving enzyme (BACE) was identified recently. However, it was not known whether BACE was the primary beta-secretase in mammalian brain nor whether inhibition of beta-secretase might have effects in mammals that would preclude its utility as a therapeutic target. In the work described herein, we generated two lines of BACE knockout mice and characterized them for pathology, beta-secretase activity and Abeta production. These mice appeared to develop normally and showed no consistent phenotypic differences from their wild-type littermates, including overall normal tissue morphology and brain histochemistry, normal blood and urine chemistries, normal blood-cell composition, and no overt behavioral and neuromuscular effects. Brain and primary cortical cultures from BACE knockout mice showed no detectable beta-secretase activity, and primary cortical cultures from BACE knockout mice produced much less Abeta from APP. The findings that BACE is the primary beta-secretase activity in brain and that loss of beta-secretase activity produces no profound phenotypic defects with a concomitant reduction in beta-amyloid peptide clearly indicate that BACE is an excellent therapeutic target for treatment of AD.
Summary
The Pallid Sturgeon is listed as federally endangered under the Endangered Species Act in the United States. When the species was listed in 1990 it was considered extremely rare and was ...poorly understood. Habitat alteration, commercial harvest, environmental contaminants, and other factors were identified as threats. Today our scientific understanding of the species and its life history requirements have increased greatly as summarized below.
The design of a neutral blocking/bypass device which can be installed in power transformer neutral-ground connections to block the flow of geomagnetically induced currents (GICs) is described. The ...device consists of standard distribution capacitors which provide the GIC blocking function. The capacitors are rapidly bypassed by a combination of sparkgap and circuit breaker to solidly ground the neutral during power system disturbances. The sparkgap provides the fast operating response speed, while the circuit breaker provides a secure metallic bypass of the capacitor. Simulation indicates that the bypass device operation will occur rapidly (on the order of 1 ms or less) and will both prevent ferroresonant overvoltages and preserve proper relay and protective device operation.< >
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