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Maintaining the s-polarization state of laser beams is important to achieve high modulation depth in a laser-interference-based super-resolution structured illumination microscope (SR-SIM). However, the imperfect optical components can depolarize the laser beams hence degenerating the modulation depth. Here, we first presented a direct measurement method designed to estimate the modulation depth more precisely by shifting illumination patterns with equal phase steps. This measurement method greatly reduces the dependence of modulation depths on the samples, and then developed a polarization optimization method to achieve high modulation depth at all orientations by actively and quantitatively compensating for the additional phase difference using a combination of waveplate and a liquid crystal variable retarder (LCVR). Experimental results demonstrate that our method can achieve illumination patterns with modulation depth higher than 0.94 at three orientations with only one LCVR voltage, which enables isotropic resolution improvement.

Our goal was to develop and experimentally validate a polarization-interference method for phase scanning of laser speckle fields generated by diffuse layers of birefringent biological tissues. This method isolates and uses new diagnostic parameters related to the “phase waves of local depolarization”. We combined polarization-interference registration with phase scanning of complex amplitude distributions in diffuse laser speckle fields to detect phase waves of local depolarization in birefringent fibrillar networks of biological tissue and measure their modulation depth. This approach led to the discovery of new criteria for differentiating various necrotic changes in diffuse histological samples of myocardial tissue from deceased individuals with “ischemic heart disease (IHD) — acute coronary insufficiency (ACI)”, even in the presence of a high level of depolarized background. To evaluate the degree of necrotic changes in the optical anisotropy of diffuse myocardial layers, a new quantitative parameter — modulation depth of local depolarization wave fluctuations — has been proposed. Using this approach, for the first time, differentiation of diffuse myocardial samples from deceased individuals with IHD and ACI was achieved with a very good 90.45% and outstanding accuracy of 95.2%.

Quantum cryptography was proposed as a counter to the capacity of quantum computers to break classical cryptosystems. A broad subclass of quantum cryptography, called quantum key distribution (QKD), relies on quantum mechanical process for secure distribution of the keys. Quantum channels are inherently noisy, and therefore these protocols will be susceptible to noise as well. In this paper, we study the performance of two QKD protocols — BB84 and E91 under amplitude damping error. We show that while E91 protocol loses its security immediately due to loss of entanglement, the performance of BB84 protocol reduces to random guessing with increasing time. Next, we consider the action of an Eve on the BB84 protocol under amplitude damping noise, who is restricted to guessing the outcome of the protocol only. Under this restriction, we show that Eve can still do better than random guessing when equipped with the characteristics of the noisy channel. Finally, we propose a modification of the BB84 protocol which retains the security of the original protocol, but ensures that Eve cannot get any advantage in guessing the outcome, even with complete channel information.

A two-dimensional modified Luo-Rudy model was created to represent a 40 mm by 40 mm slab of myocardial tissue. An inhomogeneity was introduced to simulate acute myocardial ischemia, with components of hyperkalemia, acidosis and anoxia. Simulations were carried out for various degrees of ischemia, to study both the interaction of the propagation front with the inhomogeneity, and the reconstructed signals. The simulations utilized a modified LR model, with a realistic anisotropy of myocardial tissue. Each cluster (.4 mm ×.4 mm) was given bulk electric properties, R_x and R_y (25Ω and 250Ω, respectively). The slab was stimulated and the 2D depolarization pattern was computed by numerical integration. To study ischemia, a circular inhomogeneity with concentric regions (r_o=12.8 mm{border zone, BZ}, r_i=11.2 mm{extreme zone, EZ}) regions was introduced in the model. From the 2D simulations and the regional action potentials (AP), unipolar and bipolar lead potentials were reconstructed. Time-frequency decomposition was performed on the lead signals by wavelet analysis. Isochrone and (dV/dt)_max maps were obtained to study depolarization. Our results indicate that spatial inhomogeneities yield dramatic spatial dispersion of the wavefront and are the origin of mid-frequency intra-QRS components in cardiac signals. Severe APD shortening and spatial distortion of the isochrone and upstroke maps are also observed.

This study demonstrates the development of the heart depolarization vector locus cardiogram (HPVLC, from limb leads and a modified Einthoven's triangle) as a diagnostic measure of the left ventricular depolarization strength. Our work involves the reconstruction of the "equivalent heart electrical-activity vector (HAV)" for the QRS complex from limb leads voltages of a sample ECG recording, and plotting the progression of the cardiac vector during the QRS complex.

A realistic visualization of the progression of the equivalent-dipole HAV during the QRS complex is possible by staging the HPVLC of the QRS complex from the onset of the QRS till the end of the depolarization stage. This can enable the characterization of the HPVLC by means of an analytical function. By studying the HPVLC for various electro-cardiological disorders, it is possible to determine the ranges of the analytical function's parameters for normal and disordered electro-cardiological states, for diagnostic purpose.

We have seen that the monitored ECG is theoretically derived from HAV components on the sides of the Einthoven triangle. Nevertheless, in cardiac practice, the monitored ECG is employed in diagnosis of heart diseases. From the ECG, we can obtain the heart rate, and therefrom the heart rate variability, which too has diagnostic applications. Many nonlinear methods have been proposed to analyze ECG and HRV for detection of cardiac abnormalities, using linear and nonlinear methods. Herein, we have shown how HRV signal can be analyzed in terms of four recurrence quantification analysis (RQA) features, which are then combined into an Integrated Index to enable better separation of normal and diabetic subjects.

The article presents the results of research the pre-transitional features of the behavior of solid solutions based on lead zirconate-titanate. The presence of a “special” critical temperature $T_d$ on the temperature dependences of the permittivity $𝜀(T)$ and the remanent polarization $P_r(T)$, preceding the temperature of the paraelectric phase transition at the Curie temperature $T_C$, is noted. In the temperature range $T$ < $T_d$, the $P_r(T)$ dependence obeys a power law. In the temperature range $T_d$<$T$<$T_C$, this law is not fulfilled. The results of X-ray experiments make it possible to associate this behavior with reversible disordering at $T$<$T_d$ of an ordered domain structure formed during the polarization of piezoelectric ceramics and with its irreversible disordering in the temperature range $T_d$<$T$<$T_C$. This is due to the appearance of internal mechanical stresses in a polycrystalline ferroelectric due to irreversible depolarization of the samples at temperatures $T_d$<$T$<$T_C$.

As the only high energy polarized proton collider in the world, the Relativistic Heavy Ion Collider (RHIC) has achieved a great success in colliding polarized proton beams up to 255GeV per beam energy with over 50% average store polarizations for spin physics studies. With the help of Siberian snakes as well as outstanding beam control during the acceleration, polarization loss during acceleration up to 100 GeV is negligible. However, about 10% polarization loss was observed between acceleration from 100 GeV to 255 GeV. In addition, a mild polarization deterioration during long store for physics data taking was also observed. In this paper, studies in understanding the store depolarizing mechanism is reported, including the analysis of polarization deterioration data based on the past couple of RHIC polarized proton runs.

The depolarization of dielectrics with polar molecules is considered as diffusion of points over a spherical surface. The normal (Gaussian) diffusion leads to the Debye relaxation, while the subdiffusion regime expressed in terms of fractional differential equation leads to a non-Debye relaxation law of the inverse power type. When the order α becomes 1, the relaxation takes the exponential form, but when α is close to 1 (but is not strictly equal to it) the relaxation follows firstly exponential law and then inverse power law. Because of the property of fractional derivatives, the end part of the process depends on its prehistory. This phenomenon is interpreted as regeneration of memory.