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Electroretinogram (ERG) studies have demonstrated that the retinal response to temporally modulated fast-ON and fast-OFF sawtooth flicker is asymmetric. The response to spatiotemporal sawtooth stimuli has not yet been investigated. Perceptually, such drifting gratings or diamond plaids shaded in a sawtooth pattern appear brighter when movement produces fast-OFF relative to fast-ON luminance profiles. The neural origins of this illusion remain unclear (although a retinal basis has been suggested). Thus we presented toad eyecups with sequential epochs of sawtooth, sine-wave, and square-wave gratings drifting horizontally across the retina at temporal frequencies of 2.5-20 Hz. All ERGs revealed a sustained direct-current (DC) transtissue potential during drift and a peak at drift offset. The amplitudes of both phenomena increased with temporal frequency. Consistent with the human perceptual experience of sawtooth gratings, the sustained DC potential effect was greater for fast-OFF cf. fast-ON sawtooth. Modeling suggested that the dependence of temporal luminance contrast on stimulus device frame rate contributed to the temporal frequency effects but could not explain the divergence in response amplitudes for the two sawtooth profiles. The difference between fast-ON and fast-OFF sawtooth profiles also remained following pharmacological suppression of postreceptoral activity with tetrodotoxin (TTX), 2-amino-4-phosphonobutric acid (APB), and 2,3 cis-piperidine dicarboxylic acid (PDA). Our results indicate that the DC potential difference originates from asymmetries in the photoreceptoral response to fast-ON and fast-OFF sawtooth profiles, thus pointing to an outer retinal origin for the motion-induced drifting sawtooth brightness illusion. [ABSTRACT FROM AUTHOR]

Transcranial alternating current stimulation (tACS) has until now mostly been administered as an alternating sinusoidal wave. Despite modern tACS stimulators being able to deliver alternating current with any arbitrary shape there has been no systematic exploration into the relative benefits of different waveforms. As tACS is a relatively new technique there is a huge parameter space of unexplored possibilities which may prove superior or complimentary to the traditional sinusoidal waveform. Here, we begin to address this with an investigation into the effects of sawtooth wave tACS on individual alpha power. Evidence from animal models suggests that the gradient and direction of an electric current should be important factors for the subsequent neural firing rate; we compared positive and negative ramp sawtooth waves to test this. An additional advantage of sawtooth waves is that the resulting artifact in the electroencephalogram (EEG) recording is significantly simpler to remove than a sine wave; accordingly we were able to observe alpha oscillations both during and after stimulation. We found that positive ramp sawtooth, but not negative ramp sawtooth, significantly enhanced alpha power during stimulation relative to sham (p < 0.01). In addition we tested for an after-effect of both sawtooth and sinusoidal stimulation on alpha power but in this case did not find any significant effect. This preliminary study paves the way for further investigations into the effect of the gradient and direction of the current in tACS which could significantly improve the usefulness of this technique. [ABSTRACT FROM AUTHOR]

The increased density of the urban population and frequent transportation movement has lead to parking issues in these areas. Many efforts have been made to efficiently utilize the existing parking facilities. Most of these solutions target the large-scale private and public parking facilities; however, the individual parking facilities are not much explored and exploited for reducing the parking issues. In the last few years, the Online-to-Offline (O2O) model has witnessed huge attention from the research community due to its versatile applications in many domains. The main objective of the O2O model is to create service awareness online, allowing potential users to review different offers and then visit local physical places for purchasing. The security of the users' data has always been considered a crucial factor in any public sharing platform. The blockchain model has been regarded as a solid security platform for many public sharing platforms. This work designed a blockchain framework with a novel data verification and role-based Access control method for securing the parking service data. Several experiments are performed using the sawtooth blockchain tool to investigate the performance of the proposed blockchain framework against the baseline approach concerning latency, meantime testing (MTT), throughput, transaction sending rate (TPS), and average response time (ART). The obtained results confirm that the proposed approach is scalable and feasible for smart parking and other IoT-based applications. • To the best of our knowledge, this is our novel contribution to develop an O2O based parking sharing service. • This work designed a blockchain framework with a novel data verification and role-based Access control method for securing the parking service data. • The implementation is done using the Sawtooth blockchain and then performance evaluation using the hyper-ledger caliper tool. • The experimental evaluation confirms that the proposed approach is scalable and is feasible for smart parking and other IoT-based applications. [ABSTRACT FROM AUTHOR]

In the present paper, an asymptotic approach is used to analyse the main features of weakly nonlinear waves propagating in a compressible, inviscid, nonideal gas in the presence of magnetic field. An evolution equation, which characterizes the wave process in the high frequency domain and points out the possibility of wave breaking at a finite time, is derived. The growth equation governing the behaviour of an acceleration wave is recovered as a special case. Further, we consider a sufficiently weak shock at the outset and study the propagation of the disturbance given in the form of a sawtooth profile. It is observed that the non-idealness of the gas causes an early decay of the sawtooth wave as compared to ideal case however the presence of magnetic field causes to slow down the decay process as compared to non-ideal non-magnetic case. A remarkable difference in wave profiles for planar and cylindrically symmetric flows has been observed. The effect of non-idealness, in the presence of magnetic field, on the formation of shock is more dominant in case of cylindrical symmetry as compared to planar case. [ABSTRACT FROM AUTHOR]

Compared with powder-based process of additive manufacturing, slurry-based process can fabricate the ceramic components with better green density by casting thinner layers to improve the step effect. The main objective of this study is to develop a reliable slurry-layer casting system for building ceramic green parts. A premetered slurry-feeding mechanism was built to steadily supply the slurry and prevented the ripples on the layer from pulsation. Based on the techniques of slot-die coating and tape casting, a novel coater including a coat hanger distribution chamber and a doctor blade was designed and built to observe the distribution of the specified slurry and verify the feasibility of the slurry-layer casting. The experiment results revealed the distribution chamber with a suitable coat hanger angle that can uniformly deliver the slurry to the lips of the coater. The premetered coating method can simplify the process variables involved in the casting process. The slurry feeder exerts a considerable force on the slurry to overcome the influence of the viscosity. Sawtooth effect in the slurry-layer casting was observed and eliminated through the process of slurry preloading. Furthermore, an online coater cleanup device, which possesses the features of simple structure and high efficiency of residual slurry removal, was proposed. For the slurry with different formation used in the additive manufacturing of ceramic products, this study can be a pattern to build a reliable slurry-layer casting system with the principle of simple design, low cost, and easy cleanup. [ABSTRACT FROM AUTHOR]

Purpose: The d-wave is typically elicited after the termination of an increment flash, but a decrement flash provides an alternative, and perhaps more appropriate, stimulus to elicit the d-wave. Here, we investigated the affects of stimulus polarity on the electroretinogram (ERG) response. Methods: ERG responses elicited to increment and decrement flashes of varying intensity and duration from different background levels were measured from human participants to assess the b-wave and d-wave responses as a function of adaptation level and flash polarity. Response amplitudes were measured using standard metrics for waveform analysis. Results: The amplitude of the b-wave is larger than the d-wave regardless of flash polarity when using different background levels which maximized the dynamic range of the two waveforms. However, when response amplitudes are measured from a common background, the d-wave elicited with decrement flash was larger than the b-wave elicited by an increment flash. This trend was evident across a range of background levels. The b-wave and d-wave become separate entities when flash duration reaches approximately 50 ms. Rapid-on and rapid-off sawtooth stimuli were also tested against increment and decrement step stimuli that were matched in mean luminance. These two stimulus types produced different amplitude b-wave and d-wave responses, suggesting asymmetric effects of the two stimulus types on the retinal response. Conclusions: We conclude that the response properties of the b-wave and d-wave are influenced by the duration, polarity and waveform of the stimulus, as well as the background from which the stimuli arise. [ABSTRACT FROM AUTHOR]

Highlights: [•] A X-mode W-band reflectometer is designed and installed on Experimental Advanced Superconducting Tokamak (EAST) for the first time. [•] Both density profile and fluctuations can be measured by the newly developed reflectometer. [•] The core density profile has been measured in high magnetic field condition together with V-band reflectometer. [•] Sawtooth precursor has been measured by fluctuation reflectometer in the low magnetic field condition. [Copyright &y& Elsevier]

Abstract: In accordance with the problems in test for scale factor of resonant micro optical gyro (RMOG) by turntable, a new method based on equivalent input is proposed, and this is by adding sawtooth waveform to the RMOG's phase modulator, the scale factor experimental setup is constructed, the closed-loop transfer functions under turntable input and equivalent input are analyzed, relationship between parameters of the sawtooth waveform and equivalent input is derived, the scale factor and nonlinearity are obtained by the scale factor experimental setup, the scale factor is basically identical to the test result on the turntable, but the nonlinearity also to raise from 0.98% to 0.53%, the results of test demostrate that the method can not only accurately measure the scale factor, but also effectively eliminate the measurement errors due to the vibration and imperfect precision of the turntable. [Copyright &y& Elsevier]

This study presents an investigation on both the processing and morphological aspects of cutting-based metal fibers. A self-designed multi-tooth cutter is used to efficiently make continuous long fibers under a low-speed dry-cutting condition. A finite element method-aided analysis is conducted to elucidate the mechanisms of this method. Based on both simulated and experimental results, it is found that fiber morphology shows different characteristics when different processing parameters are used. Moreover, the fiber structure and appearance also significantly depends on the mechanical properties of raw materials. It is shown that the Cu fiber belongs to flow chip due to highly plastic deformation, while the hardened Cu-Be, Cu-Be-Ni alloy and SUS316L fibers exhibit fractured features. The combined segmented vertical fins and sawtooth structures can be periodically formed on the Cu-Be fibers under an appropriate condition. Besides these findings, the effects of sintering condition on the fiber morphology are also reported in this work. [ABSTRACT FROM AUTHOR]

Sawtooth patterns in the I\--V curves of superlattices result from the bistability induced by the negative differential resistance of the local J-F curve. This behavior has been extensively studied in weakly coupled superlattices from a transport point of view. In this paper, we show that the sawtooth patterns not only affect the dark current but also the noise and responsivity properties of a quantum well infrared photodetector. Their impact on the imaging properties of the detector is also quantified. [ABSTRACT FROM PUBLISHER]

Abstract: The high performance mode (H-mode) is one of the baseline plasma scenarios for the experimental fusion reactor ITER. This scenario features a periodic crash-like reorganization of the plasma pressure and the magnetic flux in the plasma core and plasma periphery. The core instability is often referred to as the sawtooth instability while the instability at the edge of the plasma is referred to as ELM. In this paper we present an algorithm for optimized (low latency, robust and high fidelity) real-time sensing of the crashes. The algorithm is based on time-scale wavelet theory and edge-detection. It is argued that detection of crashes has considerably less delay than the other methods. The realized accuracy of the detection algorithm is well below the uncertainty of the crash period for most crashes. Multiresolution analysis enables distinction between different sizes of sawtooth crashes due to the different sizes of wavelets (scales), resulting in an algorithm, which is robust and accurate. Although strictly speaking, the crash detection method is demonstrated for sawteeth measured with ECE only, it can be applied to any periodic crash, measured with any temporally resolved data. Note that the possibility of differentiating between crash like events of different nature depends on their individual time-scales and used measurement setup. [Copyright &y& Elsevier]

Abstract: Three elderly patients with a clinical diagnosis of posterior crocodile shagreen of the cornea underwent penetrating keratoplasty. Each of the patients had the characteristic symmetrical, polygonal opacities with indistinct edges and intervening clear spaces in the central posterior corneal stroma. Electron microscopic examination of the keratoplasty specimens disclosed the presence of vacuoles throughout the corneal stroma, many of which contained electron-dense material. The vacuoles were observed with increasing density posteriorly and were most concentrated adjacent to the anterior banded portion of Descemet''s membrane. A sawtooth-like configuration of the stromal collagenous lamellae was noted in the posterior cornea in one case. We reviewed the three cases of central corneal clouding reported with histopathological findings as well as the clinical descriptions of this entity. Although a sawtooth-like lamellar configuration of the stromal collagen may be seen by electron microscopy, characteristic vacuoles appear to be the only consistent finding. We believe that posterior crocodile shagreen is most likely a degenerative disorder and that it should be distinguished from central cloudy dystrophy of François by its non-familial pattern of occurrence. [Copyright &y& Elsevier]

Abstract: A soft X-ray (SXR) imaging system composed of three miniature SXR pinhole array camera designed and installed on the joint texas experimental tokamak (J-TEXT) for the study of plasma equilibrium and fluctuation properties during ohmic discharges. The imaging system functions well, giving good resolution and maneuverability. Combined with the use of the biorthogonal decomposition technique, it helps us to analyze the sawtooth crashes and their basic parameters such as reversal surface and modes. Furthermore, the plasma displacement is measured using SXR emission and the results are compared with those from magnetic diagnostic tools. The comparisons verify that the SXR imaging system is a legitimate alternative for non-magnetic plasma offset observation. In addition, it can form the basis of a real-time feedback control system for magnetic-confined plasma. [Copyright &y& Elsevier]

Abstract: Sawtooth oscillations with post-cursor were observed in LHCD plasma on HT-7 tokamak. The mode exists and decays gradually after the crash, which implies that the magnetic reconnection is incomplete and the central safety factor remains below unity after the crash. From results of the singular value decomposition (SVD) and tomographic reconstructions describing the magnetic surface structures in the crash, it was found that the mode survives in the crash. It is shown that, the appearance of the preservation of this mode is inconsistent with the secondary reconnection theory, and we conjecture that the evolving of this mode may be understood with the stochastic field model. [Copyright &y& Elsevier]

Electrical stimuli pace, cardiovert, or defibrillate the heart by changing transmembrane potential (ΔVm). Recent simulation studies provide insights Into mechanisms by which stimuli establish ΔVm. This review attempts a nonmathematical description of these mechanisms. We start with the cable model in which the intracellular core conductor is bounded by a highly resistive and capacitive membrane that separates the intracellular and extracellular spaces. Intracellular and extracellular resistances are assumed to vary linearly with position. Although this model predicts anodal extracellular stimuli hyperpolarize adjacent tissue and cathodal extracellular stimuli depolarize that tissue, it fails to reproduce regions of opposite ΔVm distant from the electrodes, We then consider the sawtooth model in which microscopic discontinuities in intracellular resistance represent gap junctions. While model studies with such discontinuities demonstrate large ΔVm at cell ends, experimental validation of such ΔVm remains elusive. Extending the analysis to the two- and three-dimensional syncytium, we also consider the bidomain model in which intracellular, extracellular, and interstitial currents are explicitly characterized. Differences in resistance to these currents gives rise to virtual electrodes, which are experimentally observed regions of large ΔVm that arise distant from the stimulating electrode. Distant ΔVm regions are also evident when macroscopic discontinuities in intracellular resistance are introduced into the bidomain model. Such discontinuities are associated with clefts or scars that give rise to "secondary sources." Albeit the cable model offers remarkable insight the bidomain model and the concept of secondary sources provide a more complete understanding of membrane excitation, especially when combined into a unifying activating function. [ABSTRACT FROM AUTHOR]

The structures of three operating regions in HT-6B Tokamak have been studied by soft X-ray tomographic system with high sensibility and high time-space resolution. One of the requisites for forming sawtooth discharge is the effective heating action in the central region. In the sawtooth region there are five evolutional phases and five types of magnetic surface structures correspondingly; that is, the concentric, the eccentric, the double-core, the “MHD-type” and the “ultra-MHD type” magnetic surface structures. In the MHD oscillation region, there is a stable “MHD-type” magnetic surface structure. It consists of a crescent “hot core” and a circular “cold bubble” and rotates in the diamagnetic direction of electrons. In the resonant region, the resonant helical field improves the heating status and suppresses the MHD disturbances; therefore the single “MHD-type” magnetic surface changes into a sawtooth type one. [ABSTRACT FROM AUTHOR]

TRIUMF's ARIEL pre-buncher is powered by a sawtooth waveform which is the combination of 11.79 MHz, 23.57 MHz and 35.36 MHz harmonics. To upgrade the existing analog and digital hybrid LLRF control system, reduce the hardware cost, and achieve more flexible control of the system, an FPGA based digital daughter board is designed. The generation, control, and regulation of these three harmonics are all incorporated digitally inside a single FPGA. To reduce the number of RF interfaces on the motherboard, the new daughter board is designed to control the amplitude and phase of the sawtooth waveform with one channel ADC and DAC. To lock the output phase of the sawtooth waveform to the reference signal, a digital phase-locked loop is designed to lock all three harmonics to the external reference signal. The related work, including the system design of the LLRF control system and the development of the digital phase-locked loop, are presented in this paper. [ABSTRACT FROM AUTHOR]

• The causal link between the sawtooth-induced heat pulses at the plasma edge and a spontaneous L-H transition is proposed. • The edge turbulence level increases significantly when the sawtooth-induced heat pulse arriving at the plasma edge. • First time to see that the turbulent decorrelation rate increases significantly just before the L-H transition by experiment. • Both turbulent decorrelation rate and nonlinear energy transfer rate play key roles on the turbulence quench. H-modes induced by sawtooth events can be often observed in discharges with marginal auxiliary power injection in EAST. Poloidal flow shear at the very plasma edge, increasing ∼25% up to the threshold value, is observed just before the L-H transition by means of a fast reciprocating probe array in EAST. This suddenly risen poloidal flow shear, caused by the increased turbulent driven Reynolds force, is motived by the heat pulse originally released by a sawtooth crash at the plasma core. Associated with the critical poloidal flow shear, the local turbulent decorrelation rate increases significantly. The increased turbulent decorrelation rate compensated by nonlinear energy transfer rate from the turbulence to the low-frequency shear flows, exceeding the turbulence energy input rate, is sustained for several hundred microseconds till the turbulence quench happening. [ABSTRACT FROM AUTHOR]