Intense Parameter Research Articles

Effects of 2HDM in Electroweak Phase Transition

The entropy production scenarios due to the electroweak phase transition (EWPT) in the framework of the minimal extension of standard model, namely the two Higgs doublet model (2HDM), are revisited. The possibility of first order phase transition is discussed. Intense parameter scanning was done with the help of BSMPT, a C++ package. We perform numerical calculations in order to calculate the entropy production with numerous benchmark points.

External fields controlling the nonlinear optical properties of quantum cascade laser based on staircase-like quantum wells

Abstract In this paper, we present a theoretical investigation of nonlinear optical properties of AlxGa1-x As-GaAs staircase-like quantum wells heterostructure under the effects of electric, magnetic, and intense laser fields. The electronic energy levels and their corresponding wave functions are computed numerically by solving the Schrodinger equation within the effective mass approximation. The obtained results show that the applied external fields have a huge impact on the intersubband transition between the ground and the first excited levels. The optical absorption coefficient and the relative refractive index changes can be blue shifted by increasing the electric field and red shifted by increasing the intense laser field parameter. However, we can obtain either the red or the blue shift by varying the intensity of an applied magnetic field. This interesting property of the applied magnetic field can be used in the design and fabrication of optoelectronic devices based on staircase-like quantum wells and operating in the red and blue domains.

A randomised controlled trial to examine the effects of cinacalcet on bone and cardiovascular parameters in haemodialysis patients with advanced secondary hyperparathyroidism

BackgroundSecondary hyperparathyroidism may lead to increased cardiovascular risk. The use of cinacalcet may improve bone and cardiovascular health with improved parathormone (PTH) and phosphate control.MethodsThis is an open-label prospective randomised controlled trial to compare progression of cardiovascular and chronic kidney disease mineral and bone disorder (CKD-MBD) parameters. Patients were randomised to receive cinacalcet alongside standard therapy or standard therapy alone. Thirty-six haemodialysis patients who had > 90 days on dialysis, iPTH > 300 pg/mL, calcium > 2.1 mmol/L and age 18–75 years were included. Following randomization, all 36 patients underwent an intensive 12-week period of bone disease management aiming for iPTH 150-300 pg/mL. The primary outcome was change in vascular calcification using CT agatston score. Secondary outcomes included pulse wave velocity (PWV), left ventricular mass index (LVMI), carotid intima-media thickness (CIMT), augmentation index (Aix) and bone measurements. The above measurements were obtained at baseline and 12 months.ResultsThere was no evidence of a group difference in the progression of calcification (median change (IQR) cinacalcet: 488 (0 to1539); standard therapy: 563 (50 to 1214)). In a post hoc analysis combining groups there was a mean (SD) phosphate reduction of 0.3 mmol/L (0.7) and median (IQR) iPTH reduction of 380 pg/mL (− 754, 120). Regression of LVMI and CIMT was seen (P = 0.03 and P = 0.001) and was significantly associated with change of phosphate on multi-factorial analyses.ConclusionsWith a policy of intense CKD-MBD parameter control, no significant benefit in bone and cardiovascular markers was seen with the addition of cinacalcet to standard therapy over one year. Tight control of hyperphosphataemia and secondary hyperparathyroidism may lead to a reduction in LVMI and CIMT but this needs further investigation. Although the sample size was small, meticulous trial supervision resulted in very few protocol deviations with therapy.

Effects of intense laser field and position dependent effective mass in Razavy quantum wells and quantum dots

Using the effective mass and parabolic band approximations, we investigated the position-dependent effective mass and non-resonant intense laser field effects on the first and third-order corrections of the absorption and relative changes of the refraction index coefficients for intersubband transition in Razavy-like quantum wells. Calculations have been extended to the spherical Razavy-like quantum dots electronic structure. We have shown that depending on the combinations of the Razavy-like potential parameters, the quantum wells can evolve from parabolic confinement in an isolated quantum well to a configuration of two coupled quantum wells. We have shown that in general the transition energies (dipole matrix elements) between the ground state and the first excited state: i ) are decreasing (increasing) functions of M -parameter, ii ) are increasing (decreasing) functions of A -parameter, iii ) they increase (decrease) when considering the position-dependent effective mass effects, and iv ) are increasing (decreasing) functions of the intense laser field parameter. In the case of the optical absorption and relative changes in the refractive index coefficients, we have shown blueshifts or redshifts by changing the A -, M -, and α 0 -parameters and by considering the effects of the position-dependent effective mass. In spherical quantum dots, we have shown that with an appropriate value of A - and M -parameters the system can evolve from a spherical quantum dot with infinite parabolic potential. • Intense laser field effects in quantum wells and dots. • Position dependent electron effective. • Linear and nonlinear optical absorption and refraction index changes coefficients. • Spatially direct and indirect excitones can be simulated in quantum rings.

Control of electronic and optical properties of a laser dressed double quantum dot molecule by lateral electric field

We study the confined states of a molecule formed by two laterally coupled quantum dots. The static electric field and incident plane wave laser field are considered with different polarization. The respective Shrödinger equation is obtained in the framework of the high-frequency limit of Floquet theory. It is shown that the electric field has a qualitative impact on the spatial symmetry of electronic states. An in-depth study of electric and laser field combined effects show a strong correlation between them. Additionally, we show that the linear, nonlinear and total optical absorption coefficients and relative refractive index of the considered structure can be effectively tuned by changing electric field strength and intense laser field parameter. Our results indicate the possibility of controlling the optical response of double quantum dots molecule for future applications in nanostructure-based quantum information science.

Effective tuning of isotropic and anisotropic properties of quantum dots and rings by external fields

Abstract The combined effects of intense THz laser field, magnetic field and in-plane electric field on electronic states and intraband optical properties of single isotropic quantum dots and rings are investigated using the non-perturbative Floquet theory in the high-frequency limit. Here we show that the change of the electric field direction for fixed values of intense THz laser field parameter can recover the degeneracy of the excited states and the dipole-allowed transition intensities in a quantum dot. Additionally, it is shown that in isotropic quantum rings the intense THz laser and the in-plane electric field create unusual Aharonov-Bohm oscillations. For fixed values of the intense THz laser field parameter, the amplitudes of Aharonov-Bohm oscillations can be effectively tuned by changing the electric field direction. Furthermore, for fixed values of the electric field strength and the laser field parameter the intraband optical properties can be effectively tuned by changing the electric field direction. Therefore, it can be asserted that circular quantum dots or circular rings in the intense THz laser field are equivalent to anisotropic quantum dots or rings respectively, and the electric field direction effectively tunes the single-electron energy spectrum and intraband optical properties of these structures.

Analytical modeling of the CNC machine axis motion in high-speed milling with local smoothing

In high-speed milling (HSM) of free-form surfaces, the tool path is mainly characterized by a set of short discontinuous segments in tangency. These discontinuities bring an intense kinematic parameter fluctuation of the computer numerical control (CNC) machine axes. The smoothing of the programmed tool path and the optimal choice of the manufacturing process parameters ensure a high productivity with the required quality of the machined surfaces. Precise estimation of the machining time allows an accurate evaluation of the machined product cost. Thereby, this is achieved by studying the effect of the tool path smoothing and the CNC controller parameters on the axis kinematics and the following errors. This paper focuses on the geometrical modeling of the local smoothing block adopted by Sinumerik CNC. Further, a kinematic model is proposed to simulate the axis motion in linear interpolation mode with local smoothing. The identification of the interpolator reduction effect on the programmed tolerance leads to the identification of the smoothing model adopted by the CNC unit. Then, the axis kinematic behavior is modeled while taking into account the drive parameter axes defined by the manufacturer of the CNC unit. The experimental results showed a smooth variation of the axis feed rate along the smoothing blocks and a good correlation with the proposed models.

Intense laser field effects on the intersubband optical absorption and refractive index change in the [formula omitted]-doped GaAs quantum wells

In this paper, we have investigated the effects of the non-resonant intense laser field on the electronic and optical properties such as linear, nonlinear and the total optical absorption coefficient and refractive index change for transitions between two lower-lying electronic states in the GaAs-based δ-doped quantum well. Within the effective mass approximation, we calculated the eigenvalues and corresponding eigenfunctions as a function of the intense laser parameter by solving the Schrödinger equation in the laser-dressed confinement potential. The analytical expressions of the linear and third-order non-linear optical absorption coefficients and refractive index changes are obtained by using the compact-density matrix formalism. The obtained results show that the separation between ground and first excited energy levels in the δ-doped quantum well decreases in energy by the increase of the laser field intensity and this effect leads to an optical red-shift in the intersubband transitions. This behavior gives us a new degree of freedom in tunability of different device applications based on the optical transitions.

The effect of the intense laser field on the electronic states and optical properties of n-type double δ-doped GaAs quantum wells

In this work, within the effective mass approximation we have performed a theoretical study of electronic states, the intersubband-related optical absorption coefficient and relative refractive index change properties in the GaAs-based double δ-doped quantum well under non-resonant intense laser field. By solving the Schrödinger equation in the laser-dressed confinement potential, we calculated eigenvalues and corresponding eigenfunctions as an intense laser parameter. We concluded that the separation between ground and first excited energy levels in the double δ-doped quantum well increases in energy by the increase of the laser field intensity and this effect leads to an optical blue-shift in intersubband transitions. Therefore a significant tunability of the optical transitions in double δ-doped quantum well can be achieved by modulating the intensity of the intense laser field.

Laser driven intraband optical transitions in two-dimensional quantum dots and quantum rings

The intraband optical absorption have been investigated in the presence of hydrogenic donor impurity in GaAs/GaAlAs quantum dot and quantum ring in the intense laser field. The single electron energy spectrum and wave functions have been found using the effective mass approximation and exact diagonalization technique. Different selection rules are obtained for intraband transitions depending on the direction of incident light polarization. Due to the accidental degeneracy of the laser dressed impurity states the crossings of the curves of the threshold energies and the dipole matrix elements on laser field parameter have been observed. The intraband absorption coefficient is calculated for different locations of hydrogenic donor impurity and different values of intense laser field parameter. The obtained results show that the absorption spectrum can exhibit either a blue- or redshift depending on the impurity location, values of the laser field parameter and direction of incident light polarization. The obtained theoretical results indicate a novel opportunity to tune the performance of new devices, based on the quantum dots and quantum rings and to control their specific properties by means of intense laser and hydrogenic donor impurity.

Donor impurity-related intraband optical absorption in a single quantum ring: Hydrostatic pressure and intense laser field effects

The simultaneous influence of hydrostatic pressure and intense laser field on hydrogenic donor impurity states and intraband optical absorption has been investigated in GaAs/\(\mathrm{Ga}_{1-\tilde{x}}\mathrm{Al}_{\tilde{x}}\)As quantum ring. The one-electron energy spectrum and wave functions have been found using the effective mass approximation and exact diagonalization technique. The intraband absorption coefficient is calculated for different values of the hydrostatic pressure, intense laser field parameter and different locations of hydrogenic donor impurity. The simultaneous influence of hydrostatic pressure and intense laser field shows that while the increment of the first one leads only to the blueshift of the absorption spectrum, the augmentation of the second one makes the redshift. In addition, both blueshift and redshift of the spectrum have been obtained with the changes of impurity location. The obtained theoretical results indicate good controlling means of the optical spectrum of ring-like structures by the combined influence of the considered factors.

Active Vibration Suppression Based on Intelligent Control for a Long-Range Ultra-Precise Positioning System

Vibration is a significant factor that influences the performance of the long-range ultra-precise positioning system. Due to the intense nonlinearity and parameter uncertainties, it is difficult to eliminate the vibration by using a conventional PID controller. In this paper, the intelligent PID controller based on BP neural network with the ability of self-learning and strong robustness is introduced into the positioning system. Simulation and experiment are conducted and the results show that the vibration is effectively suppressed and the positioning accuracy has reached within 5.8nm.

Effects of Noninvasive Transcutaneous Electrical Stimulation via Concentric Ring Electrodes on Pilocarpine‐induced Status Epilepticus in Rats

The aim of this pilot study was to investigate the antiepileptic effects of a novel noninvasive stimulation technique, transcutaneous electrical stimulation (TcES) via scalp concentric ring electrodes, on pilocarpine-induced status epilepticus (SE) in rats. Five minutes after the onset of SE, TcES was administered to the experimental rat via bipolar concentric ring electrode at the CZ location. Symmetrical, biphasic, charge-balanced, constant current, isolated pulses were applied via a custom-made stimulator. TcES parameters ranged from 200-750 Hz, 200 or 300 mus pulse duration, and 50 or 60 mA, applied for 1 min, started with the least intense parameter set and progressively increased. TcES attenuated electrographic seizure activity and halted the progression of behavioral seizures. Interruption of seizure activity outlasted the period of stimulation and appeared to be long-lasting. TcES treatment significantly extended the life and enhanced the survival of rats after SE. Noninvasive TcES, applied 5 min after SE onset via novel concentric ring electrodes on the scalp, reduced, or abolished electrographic and behavioral seizure activity in pilocarpine-induced SE in rats. These findings suggest that TcES may have a role in the treatment of SE.