Free-boundary plasma equilibria with toroidal plasma flows

Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and the scrape-off layer are developed for the 'divertor-type' and 'limiter-type' free boundaries in the tokamak cylindrical coordinator. With a toroidal plasma flow, the flux functions are considerably different under the isentropic and isothermal assumptions. The effects of the toroidal flow on the magnetic axis shift are investigated. In a high beta plasma, the magnetic shift due to the toroidal flow are almost the same for both the isentropic and isothermal cases, and are about 0.04a0 (a0 is the minor radius) for M0=0.2 (the toroidal Alfvѐn Mach number on the magnetic axis). In addition, the X-point is slightly shifted upward by 0.0125 a0. But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M0 is usually less than 0.05 in a real tokamak. The effects of the toroidal flow on the plasma parameters are also investigated. The high toroidal flow shifts the plasma outward due to the centrifugal effect. Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case.

Influence of Temperature and Screw Pressing on the Quality of Cassava Leaf Fractions

In this study, the development of a mild processing method for cassava leaves to remove cyanogenic compounds with minimum nutritional loss is evaluated. Fresh leaves were reduced in size using a mixer at temperatures of 25 (room temperature), 55, 80, and 100 °C for 1 min before screw pressing to separate the juice and press cake fractions. Cyanide content in the fresh leaves was reduced by 60% at 100 °C and by 57% in the juice sample processed at 25 °C. The press cake cyanide content was low (210 ppm) in both the control and the sample that was processed at 55 °C. An increase in the temperature for processing cassava leaves to 100 °C resulted in a loss of 5–13% of the CP and 7–18% of the vitamin C content. The press-cake fraction had high beta-carotene, lutein, and chlorophyll a and b content, and low values were registered for the juice fraction. Processing fresh cassava leaves at 25 and 55 °C resulted in fractions with high beta-carotene and lutein content. The protein quality of press cake was better than that of juice for feed. Short thermal shredding with pressing resulted in minimal loss of nutrients and a significant reduction of cyanide in the leaves.

A Randomized, Double-Blind, Placebo-Controlled Study of the Effects of Two Sequential Doses of NV-5138 SPN-820 on Quantitative Electroencephalography in Healthy Adult Males

NV-5138 (or SPN-820) is a novel small molecule activator of the mechanistic target of rapamycin complex 1 (mTORC1) currently under development for use in treatment- resistant depression. This phase I study evaluated the safety, tolerability, and pharmacodynamics (as measured by quantitative electroencephalography, qEEG) of two sequential oral doses of NV-5138 in healthy adult males. Twenty-five participants were randomly assigned to double-blind treatment with a single dose of placebo or 2400 mg NV-5138 on Day 1, and a second dose of the same treatment on Day 3. The two doses of NV-5138 were safe and well tolerated, with no deaths, serious adverse events, or discontinuations due to adverse events. Spectral band amplitudes, derived frequency measures, and magnitude squared coherences were computed from qEEG recordings during resting state eyes-open and eyes-closed conditions at multiple timepoints. In the NV-5138 group only, significant changes in qEEG measures occurred at 1 hour post-dose on both days (near NV-5138 T max ), including decreases in low-frequency band amplitudes (theta) and increases in high-frequency EEG band amplitudes (high beta and gamma). These effects were mirrored by a decrease in the theta/beta ratio, a measure negatively associated with arousal and cognitive processing capability. Significantly increased high beta and gamma band coherences were also detected at several specific electrode pairs in both eyes-open and eye-closed conditions. NV-5138 actively modulated functional brain parameters consistent with positive effects on mood, cognition, and arousal. These results indicate that qEEG measures may be useful biomarkers of NV-5138 target engagement and related changes in neural activity.

Physiological and Psychological Effects of Visual Stimulation with Green Plant Types

This study was designed to assess the physiological and psychological benefits of visually looking at foliage plants in adults. This study involved 30 adults in their 20s (11 males, 19 females), and using a crossover design, participants looked at four different types of visual stimuli, namely, real plants, artificial plants, a photograph of plants, and no plants for 5 min. Brain waves were measured while viewing each type of plant, and a subjective evaluation of emotions was performed after each visual stimulus. Semantic differential methods (SDM) and Profile of Mood States (POMS) were used for the subjective evaluation. During the real plant visual stimulation, relative theta (RT) power spectrum was increased in the bilateral occipital lobes, while relative high beta (RHB) power spectrum was reduced in the left occipital lobe, indicating a reduction in stress, anxiety, and tension. The subjective survey results revealed that when looking at real plants, the participants exhibited significantly higher “comfort,” “natural,” and “relaxed” scores as well as an increase in positive mood conditions. In conclusion, among the four types of plants, visual stimulation with real plants induces physiological relaxation in adults and has a positive psychological effect.

Causal contributions of neural noise to left frontal networks subtending the modulation of conscious visual perception in the human brain

For several decades, the field of human neurophysiology has focused on the role played by cortical oscillations in enabling brain function underpinning behaviors. In parallel, a less visible but robust body of work on the stochastic resonance phenomenon has also theorized contributions of neural noise - hence more heterogeneous, complex and less predictable activity - in brain coding. The latter notion has received indirect causal support via improvements of visual function during non-regular or random brain stimulation patterns. Nonetheless, direct evidence demonstrating an impact of brain stimulation on direct measures of neural noise is still lacking. Here we evaluated the impact of three non frequency-specific TMS bursts, compared to a control pure high-beta TMS rhythm, delivered to the left FEF during a visual detection task, on the heterogeneity, predictability and complexity of ongoing brain activity recorded with scalp EEG. Our data showed surprisingly that the three non frequency-specific TMS patterns did not prevent a build-up of local high-beta activity. Nonetheless, they increased power across broader or in multiple frequency bands compared to control purely rhythmic high-beta bursts tested along. Importantly, non frequency-specific patterns enhanced signal entropy over multiple time-scales, suggesting higher complexity and an overall induction of higher levels of cortical noise than rhythmic TMS bursts. Our outcomes provide indirect evidence on a potential modulatory role played by sources of stochastic noise on brain oscillations and synchronization. Additionally, they pave the way towards the development of novel neurostimulation approaches to manipulate cortical sources of noise and further investigate their causal role in neural coding.

The natural frequencies of the resting human brain: an MEG-based atlas

Brain oscillations are considered to play a pivotal role in neural communication. However, detailed information regarding the typical oscillatory patterns of individual brain regions is surprisingly scarce. In this study we applied a multivariate data-driven approach to create an atlas of the natural frequencies of the resting human brain on a voxel-by-voxel basis. We analysed resting-state magnetoencephalography (MEG) data from 128 healthy adult volunteers obtained from the Open MEG Archive (OMEGA). Spectral power was computed in source space in 500 ms steps for 82 frequency bins logarithmically spaced from 1.7 to 99.5 Hz. We then applied k-means clustering to detect characteristic spectral profiles and to eventually identify the natural frequency of each voxel. Our results revealed a region-specific organisation of intrinsic oscillatory activity, following both a medial-to-lateral and a posterior-to-anterior gradient of increasing frequency. In particular, medial fronto-temporal regions were characterised by slow rhythms (delta/theta). Posterior regions presented natural frequencies in the alpha band, although with differentiated generators in the precuneus and in sensory-specific cortices (i.e., visual and auditory). Somatomotor regions were distinguished by the mu rhythm, while the lateral prefrontal cortex was characterised by oscillations in the high beta range (>20 Hz). Importantly, the brain map of natural frequencies was highly replicable in two independent subsamples of individuals. To the best of our knowledge, this is the most comprehensive atlas of ongoing oscillatory activity performed to date. Furthermore, the identification of natural frequencies is a fundamental step towards a better understanding of the functional architecture of the human brain.

Plasma beta effects on the edge magnetic field structure and divertor heat-loads in Wendelstein 7-X high-performance scenarios

To support the scenario design for the upcoming longpulse high-performance campaign of Wendelstein 7-X, this work presents a study of high-beta full-field 3D equilibria obtained with the HINT code. For three magnetic configurations of different edge-iota, the effects of both overall pressure and pressure profile changes on the magnetic topology are analyzed. Anisotropic diffusion modeling is used to obtain estimates of the conductive heat load distribution both on the divertor and other plasma-facing components in finite-beta magnetic configurations. For the magnetic standard configuration, limitations of the model are outlined by comparing measured and predicted heatloads by performing a linear regression of the main strike-line position against various plasma parameters in both the experimental and the simulated device.

Differential Effects of Pathological Beta Burst Dynamics Between Parkinson’s Disease Phenotypes Across Different Movements

Background: Resting state beta band (13–30 Hz) oscillations represent pathological neural activity in Parkinson’s disease (PD). It is unknown how the peak frequency or dynamics of beta oscillations may change among fine, limb, and axial movements and different disease phenotypes. This will be critical for the development of personalized closed loop deep brain stimulation (DBS) algorithms during different activity states.Methods: Subthalamic (STN) and local field potentials (LFPs) were recorded from a sensing neurostimulator (Activa® PC + S, Medtronic PLC.) in fourteen PD participants (six tremor-dominant and eight akinetic-rigid) off medication/off STN DBS during 30 s of repetitive alternating finger tapping, wrist-flexion extension, stepping in place, and free walking. Beta power peaks and beta burst dynamics were identified by custom algorithms and were compared among movement tasks and between tremor-dominant and akinetic-rigid groups.Results: Beta power peaks were evident during fine, limb, and axial movements in 98% of movement trials; the peak frequencies were similar during each type of movement. Burst power and duration were significantly larger in the high beta band, but not in the low beta band, in the akinetic-rigid group compared to the tremor-dominant group.Conclusion: The conservation of beta peak frequency during different activity states supports the feasibility of patient-specific closed loop DBS algorithms driven by the dynamics of the same beta band during different activities. Akinetic-rigid participants had greater power and longer burst durations in the high beta band than tremor-dominant participants during movement, which may relate to the difference in underlying pathophysiology between phenotypes.

Dopaminergic Modulation of Spectral and Spatial Characteristics of Parkinsonian Subthalamic Nucleus Beta Bursts

In Parkinson’s disease (PD), subthalamic nucleus (STN) beta burst activity is pathologically elevated. These bursts are reduced by dopamine and deep brain stimulation (DBS). Therefore, these bursts have been tested as a trigger for closed-loop DBS. To provide better targeted parameters for closed-loop stimulation, we investigate the spatial distribution of beta bursts within the STN and if they are specific to a beta sub-band. Local field potentials (LFP) were acquired in the STN of 27 PD patients while resting. Based on the orientation of segmented DBS electrodes, the LFPs were classified as anterior, postero-medial, and postero-lateral. Each recording lasted 30 min with (ON) and without (OFF) dopamine. Bursts were detected in three frequency bands: ±3 Hz around the individual beta peak frequency, low beta band (lBB), and high beta band (hBB). Medication reduced the duration and the number of bursts per minute but not the amplitude of the beta bursts. The burst amplitude was spatially modulated, while the burst duration and rate were frequency dependent. Furthermore, the hBB burst duration was positively correlated with the akinetic-rigid UPDRS III subscore. Overall, these findings on differential dopaminergic modulation of beta burst parameters suggest that hBB burst duration is a promising target for closed-loop stimulation and that burst parameters could guide DBS programming.