Electrode montage-dependent intracranial variability in electric fields induced by cerebellar transcranial direct current stimulation

Transcranial direct current stimulation (tDCS) is an increasingly popular tool to investigate the involvement of the cerebellum in a variety of brain functions and pathologies. However, heterogeneity and small effect sizes remain a common issue. One potential cause may be interindividual variability of the electric fields induced by tDCS. Here, we compared electric field distributions and directions between two conventionally used electrode montages (i.e., one placing the return electrode over the ipsilateral buccinator muscle and one placing the return electrode [25 and 35 cm2 surface area, respectively] over the contralateral supraorbital area; Experiment 1) and six alternative montages (electrode size: 9 cm2; Experiment 2) targeting the right posterior cerebellar hemisphere at 2 mA. Interindividual and montage differences in the achieved maximum field strength, focality, and direction of current flow were evaluated in 20 head models and the effects of individual differences in scalp–cortex distance were examined. Results showed that while maximum field strength was comparable for all montages, focality was substantially improved for the alternative montages over inferior occipital positions. Our findings suggest that compared to several conventional montages extracerebellar electric fields are significantly reduced by placing smaller electrodes in closer vicinity of the targeted area.

DISSIPATIVE INSTABILITIES AND SUPERRADIATION REGIMES (CLASSIC MODELS)

The generation of an electromagnetic field by oscillators in an open resonator is discussed in a one-dimensional approximation. In this case, the development of the so-called dissipative instability  the dissipative generation regime. Such an instability with the generation of electromagnetic oscillations arises when the decrement of oscillations in an open resonator in the absence of oscillators turns out to be greater than the increment of the resulting instability of the system of oscillators placed in this resonator. It is assumed that the oscillators do not interact with each other, and only the resonator field affects their behavior. If the resonator field is absent or small, the superradiance regime is possible, when the radiation of each oscillator is essential and the field in the system is the sum of all the eigenfields of the oscillators. In the dissipative regime of instability generation, the system of oscillators is synchronized by the induced resonator field. The synchronization of the oscillators in the superradiance mode owes its existence to the integral field of the entire system of oscillators. With a weak nonlinearity of the oscillators, a small initiating external field is required to excite the generation regime. It is noteworthy that the maximum value of the superradiance field is approximately two times less than the maximum field that the same particles could generate if they were at the same point. In all cases, for a given open resonator, the superradiance field turned out to be somewhat larger than the resonator field. Nevertheless, for the same resonator, the increments and attainable field amplitudes in both cases are of the same order of magnitude.

Investigation of Insulation Characteristics of GFRP Crossarm Subjected to Lightning Transient

The advancement of material technology has contributed to the variation of high-performance composites with good electrical insulation and mechanical properties. Their usage in electrical applications has grown since then. In Malaysia, the composite made of Glass Fiber Reinforced Polymer (GFRP) has been adopted for crossarm manufacturing and has successfully served 275 kV lines for a few decades. However, the combination of extreme conditions such as lightning transient and tropical climate can impose threats to the material. These issues have become major topics of discussion among the utilities in the Southeast Asian (SEA) region, and also in previous research. In Malaysia, more than 50% of total interruptions were caused by lightning. Limited studies can be found on the composite crossarm, especially on the square tube GFRP filled crossarm used in Malaysia. Therefore, this paper proposes to study the behavior of the particular GFRP crossarm, by means of its insulation characteristics. Experimental and simulation approaches are used. Throughout the study, the GFRP specimen is known to have an average breakdown strength at 7.2 kV/mm. In addition, the CFO voltages of the crossarm at different lengths are presented, whereby the behavior under dry and wet conditions is comparably discussed. At the same time, the polarity effect on the CFO voltages is highlighted. The maximum E-fields at the immediate moment before breakdown are analyzed by adopting the finite element method (FEM). Non-uniform distribution of E-fields is witnessed at different parts of the crossarm structure. Simultaneously, the maximum field localized on the crossarm immediately before the breakdown is also presented.

Synthesis of holmium orthoferrite nanoparticles by the co-precipitation method at high temperature

Holmium orthoferrite HoFeO3 nanoparticles were synthesized by a simple co-precipitation method via the hydrolysis of Ho (III) and Fe (III) cations in boiling water with 5% aqueous ammonia solution. After annealing the precipitate at 750 and 850 °C for 1 hour, the single-phase HoFeO3 product formed with particle size < 50 nm. The synthesized nanopowders are paramagnetic materials with remanent magnetization Mr < 0.01 emu·g-1, the coercive force Hc = 20÷21 Oe, and magnetization Ms ~ 2.73 emu·g-1 at 300 K in a maximum field of 16,000 Oe.

Design of a Cell Phone Lens-Based Miniature Microscope with Configurable Magnification Ratio

Application of cell-phone-based microscopes has been hindered by limitations such as inferior image quality, fixed magnification and inconvenient operation. In this paper, we propose a reverse cell phone lens-based miniature microscope with a configurable magnification ratio. By switching the objectives of three camera lens and applying the digital zooming function of the cell phone, a cell phone microscope is built with the continuously configurable magnification ratio between 0.8×–11.5×. At the same time, the miniature microscope can capture high-quality microscopic images with a maximum resolution of up to 575 lp/mm and a maximum field of view (FOV) of up to 7213 × 5443 um. Furthermore, by moving the tube lens module of the microscope out of the cell phone body, the built miniature microscope is as compact as a <20 mm side length cube, improving operational experience profoundly. The proposed scheme marks a big step forward in terms of the imaging performance and user operational convenience for cell phone microscopes.

Design and analysis of a hybrid-excited wound field synchronous machine with high reluctance torque utilization

The paper proposes a hybrid-excited wound field synchronous machine (HE-WFSM), which can achieve high reluctance torque utilization. The key of the proposed HE-WFSM is that two permanent magnets (PMs) assist each rotor pole in forming an additional magnetic flux circle. It is opposite to the magnetic flux circle along the q-axis in the WFSM. The reduction of the q-axis flux can help to improve the saliency ratio and reluctance torque. Additionally, the asymmetrical flux linkage achieves a closest current phase angle between the maximum field torque and the maximum reluctance torque. To highlight the advantages of the proposed HE-WRSM, a general WFSM was adopted as the basic machine and analyzed under the same operating conditions. All performances of the basic machine and proposed HE-WFSM were predicted using finite element analysis (FEA) in Jmag-Designer. Finally, it was confirmed that the proposed HE-WRSM can achieve high reluctance torque utilization.

FORMATION OF THE SOWING STRUCTURE AND PRODUCTIVITY OF NORTHERN EKOTYPE SOYBEAN PLANTS AT DIFFERENT SOWING METHODS IN THE CONDITIONS OF THE MIDDLE VOLGA FOREST STEPPE

The studies were carried out in order to study the effect of the row spacing on the formation of the structure and productivity of plants of the early maturing soybean of Milyausha variety. In a field experiment on gray forest soils with a weakly acidic reaction and a humus content of 3.21 ... 3.83%, two sowing methods were compared: continuous sowing with a distance between rows of 15 cm and a series of rows - 30 cm. In the conditions of Kama region of the Republic of Tatarstan in dry years (2016, 2018), the duration of the growing season of the variety did not depend on the sowing methods and was 89 ... 91 days. With a moderate temperature regime and abundant precipitation (2017), with row sowing with a row spacing of 15 cm, it increased up to 105 days, in the variant with a row spacing of 30 cm - up to 109 days. An increase in the duration of the period from sowing to emergence of seedlings with a lack of heat led to a decrease in field germination according to the variants of the experiment to 70.0 ... 72.5%, plant survival - to 57.5 ... 66.0%. The maximum field germination in the experiment (95.0 and 85.0%), safety (98.2 and 94.1%) and plant survival (93.3 and 80.0%) were noted in 2018 with a high sum of air temperatures above 10 ° C and moderate moisture (total precipitation 102 mm) during the growing season. In the variant with a row spacing of 30 cm, the mass of seeds per plant in arid conditions was higher than with continuous sowing, by 2.2 ... 2.7, and in conditions of excessive moisture - by 1.7 times. An increase in the mass of seeds provided an increase in branching, the number of beans and seeds per plant. In terms of productivity and yield per unit area, there were no significant differences between the options for sowing methods. The maximum realization of the potential of productivity (289.1 and 314.7 g / m2) and yield (2.78 and 2.81 t / ha) in the experiment was achieved with the duration of the growing season 105 and 109 days (2017)

Research of water-physical properties of soil with application of hydrogel in the Kurchum district of the Eastern-Kazakhstan region

The purpose of the research is to study the water-physical parameters of the soil, on the basis of which it is possible to analyze the moisture regime and draw conclusions about the applied innovative technologies. The results of the experiments; set according to the developed recommendations by the employees of the Altay Botanical Garden. The article provides data on the water-physical properties of the soil: density, humidity and maximum field moisture capacity. The results of the experiments showed that with the help of the «Akvasorb» hydrogel, it is possible to regulate the water regime of soils and increase the moisture reserves available to plants in conditions of water scarcity. Thus, the addition of the preparation at a rate of 1.5 kg/m3 and 2.0 kg/m3 helps to retain the greatest amount of moisture in the soil from 15 % to 24 % across all horizons. These same norms increase the water reserves in the oil, especially in the spring and improve its density. All this contributes to a better development of plants.