Secret Communication Systems Using Chaotic Wave Equations with Neural Network Boundary Conditions

In a secret communication system using chaotic synchronization, the communication information is embedded in a signal that behaves as chaos and is sent to the receiver to retrieve the information. In a previous study, a chaotic synchronous system was developed by integrating the wave equation with the van der Pol boundary condition, of which the number of the parameters are only three, which is not enough for security. In this study, we replace the nonlinear boundary condition with an artificial neural network, thereby making the transmitted information difficult to leak. The neural network is divided into two parts; the first half is used as the left boundary condition of the wave equation and the second half is used as that on the right boundary, thus replacing the original nonlinear boundary condition. We also show the results for both monochrome and color images and evaluate the security performance. In particular, it is shown that the encrypted images are almost identical regardless of the input images. The learning performance of the neural network is also investigated. The calculated Lyapunov exponent shows that the learned neural network causes some chaotic vibration effect. The information in the original image is completely invisible when viewed through the image obtained after being concealed by the proposed system. Some security tests are also performed. The proposed method is designed in such a way that the transmitted images are encrypted into almost identical images of waves, thereby preventing the retrieval of information from the original image. The numerical results show that the encrypted images are certainly almost identical, which supports the security of the proposed method. Some security tests are also performed. The proposed method is designed in such a way that the transmitted images are encrypted into almost identical images of waves, thereby preventing the retrieval of information from the original image. The numerical results show that the encrypted images are certainly almost identical, which supports the security of the proposed method.     

A directly fused tetrameric porphyrin sheet and its anomalous electronic properties that arise from the planar cyclooctatetraene core

Oxidation of a directly meso-meso linked cyclic porphyrin tetramer 2 gave a porphyrin sheet 3. The symmetric square structure of 3 is indicated by its simple 1H NMR spectrum that exhibits only two signals for the porphyrin beta-protons. The absorption spectrum of 3 displays characteristic Soret-like broad bands and weak Q-bands, and its magnetic circular dichroism (MCD) spectrum exhibits a negative Faraday A term at the 762 nm band as a rare case, indicating the absorption as a transition from a nondegenerate level to a degenerate level. A slightly longer S1-state (1.1 ps) and smaller TPA cross section (2750 GM) than a tetrameric linear porphyrin tape also indicate its unique electronic properties. The porphyrin sheet 3 forms stable 1:2 complexes with guest molecules G1 and G2, whose 1H NMR spectra exhibit remarkable downfield shifts for the guest protons that are located just above the cyclooctatetraene (COT) core of 3, whereas the imidazolyl protons bound to the zinc(II) porphyrin local cores are observed at slightly upfield positions. These results have been qualitatively accounted for in terms of the presence of a strong paratropic ring current around the COT core that propagates through the whole pi-electronic network of 3, hence competing with and cancelling the weak diatropic ring currents of the local zinc(II) porphyrins. This explanation was supported by DFT calculation performed at the GIAO-B3LYP/6-31G level, which indicated large positive NICS values within the COT core and small NICS values within the local zinc(II) porphyrins.     

Bubble population phenomena in sonochemical reactor: II. Estimation of bubble size distribution and its number density by simple coalescence model calculation

A simple bubble population model, with emphasis on the bubble–bubble coalescence, is proposed. In this model, the bubble size distribution is simulated through the iteration of fundamental bubble population process: generation, dissolution, and coalescence. With this simple modelling, the bubble size distribution experimentally observed by the pulsed laser diffraction method and the void rate obtained by the capillary system at 443 kHz were successfully simulated. The experimental results on the bubble population growth by the repetitive pulsed sonication and the effect of pulse width on the bubble population were recreated by the numerical simulation in a semi-quantitative manner. The importance of coalescence of bubbles especially for the effect of addition of surfactant is demonstrated. By decreasing the coalescence frequency by one order of magnitude in the simulation, both the drastic decrease in the total bubble volume as well as the depression of bubble size distribution centring from a few tens of microns in water to a few microns in a dilute surfactant solution can be simultaneously derived.     

Bubble population phenomena in sonochemical reactor: I Estimation of bubble size distribution and its number density with pulsed sonication – Laser diffraction method

To characterize the bubble populations (size and its number distribution) in a sonochemical reactor, a simple but powerful technique based on the Fraunhofer laser diffraction (LD) has been proposed. In this method, the acoustic wave disturbance to the laser probe in the sonochemical reaction field was eliminated by the temporal separation using pulsed sonication (pulsed LD). With this relatively simple strategy, the temporal development of the bubble size distribution could be evaluated by pulsed LD. A number density of bubbles was estimated by using a calibration data obtained with monosized standard particles. In addition, the effect of pulse length and a surfactant on the bubble population phenomena in a multibubble system are discussed.     

Practical synthesis of adenosine 3′,5′-cyclic monophosphorodithioate

Adenosine 3′,5′-cyclic monophosphorodithioate (cAMPS₂), which has two exocyclic sulfurs directly attached to phosphorus, was synthesized from adenosine phosphoramidite by intramolecular cyclization employing the phosphotriester method as a key step.     

Spatial frequency channels for stereoscopic depth perception

We investigated spatial frequency tuning of the mechanisms for stereoscopic depth perception, using a masking technique, and compared these tunings with those for luminance pattern detection. Observers discriminated depth direction in random-dot stereograms with various contrasts of a masking pattern, which was dichoptic stimulus of uncorrelated random dots. The strength of masking effect as a function of spatial frequency (i.e., masking function) was measured: masking function approximates the spatial frequency tuning of the mechanism that detects the depth in the test pattern. The masking functions for stereoscopic depth were found to be similar to either of the three of the six spatial frequency channels proposed by Wilson and Gelb (1984) for the detection of luminance patterns.     

Quantum chemical studies on the role of water microsolvation in interactions between group 12 metal species (Hg2+, Cd2+, and Zn2+) and neutral and deprotonated cysteines

Interactions of group 12 metal(II) species (Hg²⁺, Cd²⁺, Zn²⁺, Hg(H₂O) _n ²⁺ , Cd(H₂O) _n ²⁺ , and Zn(H₂O) _n ²⁺ (n?=?1, 2) with neutral (RSH), deprotonated (RS^?), and doubly deprotonated cysteine species (abbreviated as ??H₂cys??, ??Hcys^???, and ??cys^2???, respectively) are examined with the Becke three-parameter Lee?CYang?CParr (B3LYP) hybrid functional after preliminary screening in a conformation analysis with the Parameterized Model number 3 (PM3) semiempirical method. Effects of water on aqueous solution are evaluated by microsolvation and polarized continuum model (PCM) approaches. In the most stable conformations of M(H₂cys)²⁺ and M(Hcys)⁺ complexes (M?=?Hg²⁺, Cd²⁺, and Zn²⁺), the SH group of the cysteine moiety is already deprotonated and undergoes strong binding with the metal ion. Among Hg(H₂cys)²⁺ complexes, cysteine complexes of Hg²⁺ without deprotonation of the SH group and mercury(II) carboxylato-type structures are at least 83 and 117?kJ/mol less stable in energy than the most stable complex (B3LYP/6-311++G(d,p)-SDD+d+f//B3LYP/6-31G(d)-SDD+d). Although Zn²⁺ binds more strongly than Hg²⁺ to a H₂cys molecule at the high-level CCSD(T)/6-311++G(d,p)-SDD+d+f//B3LYP/6-311++G(d,p)-SDD+d+f level, [Hg(H₂O)₂]²⁺ is stronger than [Zn(H₂O)₂]²⁺ because the deformation of [Zn(H₂O)₂]²⁺ required to bind to cys is much more than in [Hg(H₂O)₂]²⁺. Complexes with a deprotonated cysteine, M(Hcys)⁺ and M(cys), prefer a multidentate structure.     

Electron- or hole-transporting nature selected by side-chain-directed π-stacking geometry: liquid crystalline fused metalloporphyrin dimers

Novel liquid crystalline (LC) semiconductors were prepared from the copper complex of a fused porphyrin dimer as the electroactive core by attaching to its periphery dodecyl and semifluoroalkyl side chains site-specifically (P≡P(hetero)) and semifluoroalkyl side chains alone (P≡P(homo)). The former and latter formed rectangular columnar and orthorhombic LC mesophases, respectively, where the stacking geometries of the π-conjugated core are quite different from one another. Although the π-electronic properties of the core units in P≡P(hetero) and P≡P(homo) in solution are substantially identical to one another, transient photocurrent profiles of their LC states under time-of-flight conditions clearly showed that P≡P(hetero) behaves as an n-type semiconductor, whereas P≡P(homo), in contrast, behaves as a p-type semiconductor.     

Edge states of Sr2RuO4 detected by in-plane tunneling spectroscopy

Tunneling spectroscopy has been performed on Sr(2)RuO(4) searching for the edge states peculiar to topological superconductivity. Conductance spectra exhibit broad humps with three types of peak shape: domelike peak, split peak, and two-step peak. By comparing the experiments with predictions for unconventional superconductivity, these varieties are shown to originate from multiband chiral p-wave symmetry with weak anisotropy of pair amplitude. The broad hump in the conductance spectrum is a direct manifestation of the edge state due to chiral p-wave superconductivity.     

Hierarchical conceptual clustering based on quantile method for identifying microscopic details in distributional data

Advances in Data Analysis and Classification - Symbolic data is aggregated from bigger traditional datasets in order to hide entry specific details and to enable analysing large amounts of data,...