Transcranial Direct Current Stimulation Enhances Muscle Strength of Non-dominant Knee in Healthy Young Males

Transcranial direct current stimulation (tDCS) has been applied in training and competition, but its effects on physical performance remain largely unknown. This study aimed to observe the effect of tDCS on muscular strength and knee activation. Nineteen healthy young men were subjected to 20 min of real stimulation (2 mA) and sham stimulation (0 mA) over the primary motor cortex (M1) bilaterally on different days. The maximal voluntary contraction (MVC) of the knee extensors and flexors, and surface electromyography (sEMG) of the rectus femoris (RF) and biceps femoris (BF) were recorded before, immediately after, and 30 min after stimulation. MVC, rate of force development (RFD), and sEMG activity were analyzed before and after each condition. MVC of the non-dominant leg extensor and flexor was significantly higher immediately after real stimulation and 30 min after stimulation than before, and MVC of the non-dominant leg flexor was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). The RFD of the non-dominant leg extensor and flexor immediately after real stimulation was significantly higher than before stimulation, and the RFD of the non-dominant leg extensor immediately after real stimulation and 30 min after stimulation was significantly higher than that of sham stimulation (P < 0.05). EMG analysis showed the root mean square amplitude and mean power frequency (MPF) of the non-dominant BF and RF were significantly higher immediately after real stimulation and 30 min after stimulation than before stimulation, and the MPF of the non-dominant BF EMG was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). Bilateral tDCS of the M1 can significantly improve the muscle strength and explosive force of the non-dominant knee extensor and flexor, which might result from increased recruitment of motor units. This effect can last until 30 min after stimulation, but there is no significant effect on the dominant knee.

A review of some amplitude-based seismic geometric attributes and their applications

Seismic interpreters frequently use seismic geometric attributes such as coherence, dip, curvature, and aberrancy for defining geological features, including faults, channels, angular unconformities, etc. Some of the commonly used coherence attributes, e. g. cross-correlation or energy ratio similarity are sensitive to only waveform shape changes, whereas the dip, curvature, aberrancy attributes are based on changes in reflector dips. There is another category of seismic attributes, which includes attributes that are sensitive to amplitude values. Root mean square amplitude is one of the better-known amplitude-based attributes, whereas coherent energy, Sobel-filter similarity, normalized amplitude gradients, and amplitude curvature are amongst lesser-known amplitude-based attributes. We compute not-so-common amplitude-based attributes on the Penobscot seismic survey from the Nova Scotia continental shelf consisting of the east coast of Canada, to bring out their interpretative value. We analyze seismic attributes at the level of the top of the Wyandot Formation that exhibits different geological features, including a synthetic transfer zone with two primary faults and several secondary faults, polygonal faults associated with differential compaction, as well as fixtures related to basement related faults. The application of the amplitude-based seismic attributes defines such features accurately. We take these applications forward by describing a situation where some geological features do not display any bending of reflectors, but only exhibit changes in amplitude. One of such examples is the Cretaceous Cree Sand channels, present in the same 3D seismic survey used for the previous applications. We compute amplitude curvature attributes and identify the channels, whereas these channels are not visible on the structural curvature display. In both the applications, we observe that appropriate corendering not-so-common amplitude based seismic attributes leads to convincing displays, that can be of immense aid in seismic interpretation and help define the different subsurface features with more clarity.

Health Indicators to Estimate Health of Magnetic Wheel Encoder

Performance of several vehicle safety features, such as anti-lock brake system (ABS), traction control system (TCS) and electronic stability control (ESC) rely on the quality of wheel speed signal. One potential failure mode for the wheel speed encoders is gradual deposition of foreign paramagnetic debris on the surface of the encoder. This results in reduced strength of the magnetic field, and impacts the quality of the wheel speed signal. Noisy wheel speed signal jeopardizes performance of safety critical features, affecting safety, stability, drivability, and negatively impacts customer’s experience. In this paper, several faulty encoders with various levels of faults have been used in data collection in a test bench. A prognostics methodology is proposed to evaluate the magnetic wheel encoder’s health. This method leverages time domain and frequency domain-based health indicators to monitor the deterioration in wheel encoder. Time domain-based health indicators include VDA (Verband der Automobilindustrie) signals that are generated by advanced wheel speed sensors, and an enveloping filter of the wheel speed signal’s noise. Frequency domain-based health indicator include root mean square amplitude of average order spectrum of wheel speed noise. The performance of individual/combination of these health indicators are compared to assess the separation between healthy encoder and degraded encoders. Results indicate that it is possible to monitor the degradation process due to magnetic debris accumulation, using the proposed method.

A 3D geological model of a structurally complex relationships of sedimentary Facies and Petrophysical Parameters for the late Miocene Mount Messenger Formation in the Kaimiro-Ngatoro field, Taranaki Basin, New Zealand

The present study investigates the reservoir characteristics of the Mount Messenger Formation of Kaimiro-Ngatoro Field which was deposited in deep-water environment. A 3D seismic dataset, core data and well data from the Kaimiro-Ngatoro Field were utilized to identify lithofacies, sedimentary structures, stratigraphic units, depositional environments and to construct 3D geological models. Five different lithologies of sandstone, sandy siltstone, siltstone, claystone and mudstone are identified from core photographs, and also Bouma sequence divisions are also observed. Based on log character Mount Messenger Formation is divided into two stratigraphic units slope fans and basin floor fans; core analysis suggests that basin floor fans show better reservoir qualities compared to slope fan deposits. Seismic interpretation indicates 2 horizons and 11 faults, majority of faults have throw less than 10 m, and most of the faults have high angle dips of 70–80°. The Kaimiro and Ngatoro Fields are separated by a major Inglewood fault. Variance attribute helped to interpret faults, and other seismic attributes such as root-mean-square amplitude, envelope and generalized spectral decomposition also helped to detect hydrocarbons. The lithofacies model was constructed by using sequential simulation indicator algorithm, and the petrophysical models were constructed using sequential Gaussian simulation algorithm. The petrophysical parameters determined from the models comprised of up to ≥ 25% porosity, permeability up to around 600mD, hydrocarbon saturation up to 60%, net to gross varies from 0 to 100%, majority of shale volumes are around 15–20%, the study interval mostly consists of macropores with some megapores and 4 hydraulic flow units. This study best characterizes the deep-water turbidite reservoir in New Zealand.

Neuromuscular Adjustments Following Sprint Training with Ischemic Preconditioning in Endurance Athletes: Preliminary Data

This preliminary study examined the effect of chronic ischemic preconditioning (IPC) on neuromuscular responses to high-intensity exercise. In a parallel-group design, twelve endurance-trained males (VO2max 60.0 ± 9.1 mL·kg−1·min−1) performed a 30-s Wingate test before, during, and after 4 weeks of sprint-interval training. Training consisted of bi-weekly sessions of 4 to 7 supra-maximal all-out 30-s cycling bouts with 4.5 min of recovery, preceded by either IPC (3 × 5-min of compression at 220 mmHg/5-min reperfusion, IPC, n = 6) or placebo compressions (20 mmHg, PLA, n = 6). Mechanical indices and the root mean square and mean power frequency of the electromyographic signal from three lower-limb muscles were continuously measured during the Wingate tests. Data were averaged over six 5-s intervals and analyzed with Cohen’s effect sizes. Changes in peak power output were not different between groups. However, from mid- to post-training, IPC improved power output more than PLA in the 20 to 25-s interval (7.6 ± 10.0%, ES 0.51) and the 25 to 30-s interval (8.8 ± 11.2%, ES 0.58), as well as the fatigue index (10.0 ± 2.3%, ES 0.46). Concomitantly to this performance difference, IPC attenuated the decline in frequency spectrum throughout the Wingate (mean difference: 14.8%, ES range: 0.88–1.80). There was no difference in root mean square amplitude between groups. These preliminary results suggest that using IPC before sprint training may enhance performance during a 30-s Wingate test, and such gains occurred in the last 2 weeks of the intervention. This improvement may be due, in part, to neuromuscular adjustments induced by the chronic use of IPC.

Transcranial Direct Current Stimulation Enhances Muscle Strength of Non-dominant Knee in Healthy Young Males

Background: Transcranial direct current stimulation (tDCS) has been applied in training and competition, but its effects on physical performance remain largely unknown. The present study aimed to observe the effect of tDCS on muscular strength and activation of the knee in healthy subjects. Methods: Nineteen healthy young males were subjected to 20 min real stimulation (2 mA) and sham stimulation (0 mA) on different days. The maximal voluntary contraction (MVC) of knee extensors and flexors and surface electromyography (sEMG) of the rectus femoris (RF) and biceps femoris (BF) were recorded before, immediately after, and 30 min after stimulation. MVC, rate of force development (RFD), and sEMG activity were analyzed before and after each condition. Results: MVC of left leg extensor and flexor was significantly higher immediately after real stimulation and 30 min after stimulation than before, and MVC of left leg flexor was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). The RFD of left leg extensor and flexor immediately after real stimulation was significantly higher than before stimulation, and the RFD of left leg extensor immediately after real stimulation and 30 min after stimulation was significantly higher than that of sham stimulation (P < 0.05). EMG analysis showed the root mean square amplitude(RMS) and mean power frequency (MPF) of left BF and RF were significantly higher immediately after real stimulation and 30 min after stimulation than before stimulation, and the MPF of left BF EMG was significantly higher 30 min after real stimulation than that after sham stimulation (P < 0.05). Conclusions: Bilateral tDCS of the primary motor cortex can significantly improve the muscle strength and explosive force of the non-dominant knee extensor and flexor, which is manifested by the increase of the amount of motor units recruited during exercise. This effect can last until 30 min after stimulation, but there is no significant effect on the dominant knee.

Perceptual and Acoustic Characteristics of Speech Clarity with and Without a Facemask

Some studies have found that the speech of speakers wearing facemasks has reduced intelligibility. Although it has been found that facemasks attenuated high-frequency energy, no study has examined the effects of masks on spectral characteristics of vowels or voiceless fricative consonants. The present study investigated auditory perceptual rating of speech clarity and acoustic-phonetic measures of vowels and voiceless fricative consonant production in 16 health care workers who produced standardized voice tasks without and with wearing either a standard surgical mask or a KN95 mask. Voice samples were perceptually rated for speech clarity and were acoustically analysed for root-mean-square amplitude (ARMS), spectral moments of two voiceless fricatives /s/ and /ʃ/, and ARMS and amplitude of the first three formants (A1, A2, and A3). Speech produced whilst wearing either a surgical or KN95 mask was significantly less clear than without a mask, with KN95 showing greater impact than surgical masks. In both fricatives, ARMS was lower in the surgical mask and KN95 mask conditions compared to the non-mask condition. None of the amplitude measures of vowels were affected by facemasks. Linear regression models indicated that perception of speech produced by mask users was mainly affected by modification of voiceless fricative consonant characteristics.

Delineation of reservoir channels by different seismic attributes and geobody extractions for robust volumetric estimation, Saffron Field, offshore Nile Delta, Egypt

The Nile Delta Basin is a major gas province. Commercial gas discoveries there have been proven mainly in Pleistocene to Oligocene sediments, and most discoveries are within sandstone reservoirs. Three-dimensional seismic data acquired over the basin have helped greatly in imaging and visualization of stratigraphy and structure, leading to robust understanding of the subsurface. Channel fairways serve as potential reservoir units; hence, mapping channel surfaces and identifying and defining infill lithology is important. Predicting sand distribution and reservoir presence is one of the key tasks as well as one of the key uncertainties in exploration. Integrating state-of-the-art technologies, such as including 3D seismic reflection surveys, seismic attributes, and geobody extractions, can reduce this uncertainty through recognition and accurate mapping of channel features. In this study, seismic attribute analysis, frequency analysis through spectral decomposition (SD), geobodies, and seismic sections have been used to delineate shallow Plio-Pleistocene El Wastani Formation channel fairways within the Saffron Field, offshore Nile Delta, Egypt. This has led to providing more reliable inputs for calculation of volumetrics. Interpretation of the stacked-channels complex through different seismic attributes helped to discriminate between sand-filled and shale-filled channels and in understanding their geometries. Results include more confident delineation of four distinct low-sinuosity channelized features. Petrophysical evaluation conducted on five wells penetrating Saffron reservoirs included electric logs and modular dynamic test data interpretation. The calculated average reservoir properties were used in different volumetric calculation cases. Different approaches were applied to delineate channel geometries that were later used in performing different volumetric cases. These approaches included defining channels from root-mean-square amplitude extractions, SD color-blended frequencies, and geobodies, all calculated from prestack seismic data. The different volumetric cases performed were compared against the latest field volume estimates proven after several years of production in which an area-versus-depth input showed the closest calculated hydrocarbon volumes to the actual proven field volumes.

Electromyographic analysis of transversus abdominis/internal oblique muscles during the execution of pelvic patterns of proprioceptive neuromuscular facilitation

Objective: To evaluate the electromyographic response of the transversus abdominis/internal oblique muscles (TrA/IO) during the execution of the four pelvic patterns of proprioceptive neuromuscular facilitation (PNF). Methods: Cross-sectional study. Were evaluated 21 women aged 18-38 years. The right TrA/IO complex, ipsilateral to the execution of a PNF combination of isotonics technique was monitored by surface electromyography. Three repetitions were performed with two-minute intervals between them in the four PNF pelvic patterns: anterior elevation, posterior depression, anterior depression, and posterior elevation. For the analysis of the electromyographic signal, a period of 500ms adjusted to the central value was extracted and the Root Mean Square amplitude was analyzed. Descriptive statistics and ANOVA test was used with a 95% confidence interval. Results: There was a higher TrA/IO activity in the concentric phase in the anterior elevation pattern (36.2 ± 32.3%) when compared to previous depression (19.5 μV ± 12.9), posterior elevation (16.1 μV ± 8.7), posterior depression 14.6μV ± 5.9). In addition, in the antero-elevation there is greater activation of the TrA/IO muscle complex when compared to the other patterns (p <0.01). Conclusion: The higher EMG response of the TrA/IO found in the anterior elevation pattern reveals its usefulness for clinical use.