Gain-Loss Evaluation-Based Generic Selection for Steganalysis Feature

Fewer contribution feature components in the image high-dimensional steganalysis feature are able to increase the spatio-temporal complexity of detecting the stego images, and even reduce the detection accuracy. In order to maintain or even improve the detection accuracy while effectively reducing the dimension of the DCTR steganalysis feature, this paper proposes a new selection approach for DCTR feature. First, the asymmetric distortion factor and information gain ratio of each feature component are improved to measure the difference between the symmetric cover and stego features, which provides the theoretical basis for selecting the feature components that contribute to a great degree to detecting the stego images. Additionally, the feature components are arranged in descending order rely on the two measurement criteria, which provides the basis for deleting the components. Based on the above, removing feature components that are ranked larger differently according to two criteria. Ultimately, the preserved feature components are used as the final selected feature for training and detection. Comparison experiments with existing classical approaches indicate that this approach can effectively reduce the feature dimension while maintaining or even improving the detection accuracy. At the same time, it can reduce the detection spatio-temporal complexity of the stego images.

CaRM: Retrieving exoplanets transmission spectra with high resolution spectroscopy

<div>High resolution spectra is the standard source to derive precise radial velocities. With the development of state-of-art instrumentation, like ESPRESSO, we are able to have higher resolutions and long term stability.</div> <div>During a transit the star light from a observer point of view is filtered in the day-night terminator of the exoplanet. As the light transverses it, diverse chemical species, dust, hazes and clouds let an imprint in the host star light. This allows to detect exoplanet atmospheres using transmission spectroscopy. However, a chromatic approach of the Rossiter-McLaughlin (RM) effect also permits to measure the planet radius wavelength dependence as a composition proxy.</div> <div>The Rossiter-McLaughlin effect is an phenomenon in radial velocities. When a star rotates, there is a velocity distribution created by the half of the surface that is moving towards the observer, presenting a intrinsic blueshift, compensated by the redshifted portion rotating away. A transiting planet produces an asymmetric distortion of the stellar line profiles of an observer giving origin to a RM profile.</div> <div>We present CaRM (Chromatic Rossiter-McLaughlin), a code developed to retrieve the transmission spectrum of an exoplanet using HARPS and ESPRESSO data. It employs a Markov chain Monte Carlo algorithm to fit two distinct RM models, with a linear or quadratic limb-darkening law, to Cross Correlated spectra. The orbital parameters retrieved as result, e.g. spin-orbit misalignment, are of foremost importance when constraining the models of planetary formation and evolution.</div> <div>A chromatic approach to the RM has been used in HD 189733b HARPS transit data, which is reproduced by this code with a good degree of agreement to previous results. We expect now to apply CaRM to ESPRESSO data (ESO-VLT), taking this method to a new level.</div>

Supramolecular chirogenesis in zinc porphyrins: Complexation with enantiopure thiourea derivatives, binding studies and chirality transfer mechanism

Complexation of three (1[Formula: see text],2[Formula: see text]-2-aminocyclohexyl arylthioureas (aryl [Formula: see text] 3,5-bis(trifluoromethyl)phenyl; phenyl; 3,5-dimethylphenyl) as the guests to ZnTPP and ZnOEP hosts has been studied by means of UV-vis, CD spectroscopies and computational simulation. The complexation proceeds via coordination of the primary amino group to the zinc ion of the metalloporphyrin and induces a moderate circular dichroism signal in the Soret band of the porphyrins. The association constants increase with larger electron-withdrawing properties of the porphyrin host and larger electron-donating ability of the guest, indicating predominantly electrostatic (Lewis acid-base) character of the complexation. Computational study of the (1[Formula: see text],2[Formula: see text]-2-aminocyclohexyl-(3,5-bis(trifluoromethyl)phenyl)thiourea and ZnTPP complex revealed slight asymmetric distortion of the porphyrin plane caused by the chiral guest and additional [Formula: see text]–[Formula: see text] interactions between the host and guest molecules. The calculated CD spectrum for the same system reproduces the experimentally observed one.

RESULTS OF POLARIZED LIGHT USE FOR STUDY OF STRESS-STRAIN STATE OF CORNEA IN PATHOLOGY OF EXTRAOCULAR MUSCLES

The parameters of interference patterns observed on the cornea in a polarized light in pathology of extraocular muscles were quantitatively evaluated. A study of the shape of 147 interference patterns observed on the cornea in a polarized light showed that the horizontal deviation of an eye in 56 % of cases was caused by the displacement of the attachment of the upper rectus muscle towards the inner rectus muscle. During illumination of the cornea of a live eye with polarized light, a specific interference pattern in the form of a rhombus formed by rainbow stripes (isochromes) is observed. It is established that such an interference pattern is the result of the influence of extraocular muscles on the cornea. The findings showed that the weakening of the force of one of muscles leads to asymmetric distortion of the shape of the interference rhombus, which is manifested with a reduced length of the corresponding section of the diagonal. On the contrary, as the force of the muscle increases, the corresponding section of the diagonal enhances. The displacement of the attachment site of direct extraocular muscle along the line of action is equivalent to a change in effort on its part, indicated appropriately by the shape of the interference rhombus. As the muscle moves away from the line of action, the angle of the interference rhombus is shifted away from the corresponding meridian. Key words: polarized light, optical anisotropy, cornea, extra−ocular muscles, interference picture.

Asymmetric Distortion Function for JPEG Steganography Using Block Artifact Compensation

This article describes how the existing distortion functions for JPEG steganography allot same cost for ±1 embedding changes. Because of the correlation of natural image, however, changes with different polarities make different influences on image. Therefore, the embedding costs for ±1 embedding changes should not be equivalent. This article proposes a general method to distinguish the embedding costs for different polarities of embedding changes for JPEG images with the help of reference images constructed by block artifact compensation. The original JPEG image is decompressed into spatial domain firstly, and then the block artifact is compensated by smoothing filtering implemented on border pixels of each 8 × 8 block. After that, the compensated image which is more similar to the original uncompressed image is recompressed into DCT domain and adopted as side information to guide the adjusting of the given distortion function. Experiment results show that after the proposed method is employed, the security performance of current popular JPEG steganographic methods is observably increased.

All-atom molecular dynamics of the HBV capsid reveals insights into biological function and cryo-EM resolution limits

The hepatitis B virus capsid represents a promising therapeutic target. Experiments suggest the capsid must be flexible to function; however, capsid structure and dynamics have not been thoroughly characterized in the absence of icosahedral symmetry constraints. Here, all-atom molecular dynamics simulations are leveraged to investigate the capsid without symmetry bias, enabling study of capsid flexibility and its implications for biological function and cryo-EM resolution limits. Simulation results confirm flexibility and reveal a propensity for asymmetric distortion. The capsid’s influence on ionic species suggests a mechanism for modulating the display of cellular signals and implicates the capsid’s triangular pores as the location of signal exposure. A theoretical image reconstruction performed using simulated conformations indicates how capsid flexibility may limit the resolution of cryo-EM. Overall, the present work provides functional insight beyond what is accessible to experimental methods and raises important considerations regarding asymmetry in structural studies of icosahedral virus capsids.

Noise generation by turbulence–propeller interaction in asymmetric flow

This paper is concerned with a particular source of both broadband and tonal aeroengine noise, termed unsteady distortion noise. This noise arises from the interaction between turbulent eddies, which occur naturally in the atmosphere or are shed from the fuselage, and the rotor. This interaction produces broadband noise across a broad frequency spectrum. In cases in which there is strong streamtube contraction, which is especially true for open rotors at low-speed conditions (such as at take-off or for static testing), tonal noise at frequencies equal to multiples of the blade passing frequency are also produced, owing to the enhanced axial coherence caused by eddy stretching. In a previous paper (Majumdar & Peake, J. Fluid Mech., vol. 359, 1998, pp. 181–216), a model for unsteady distortion noise was developed in axisymmetric flow. However, asymmetric situations are also of much interest, and in this paper we consider two cases of asymmetric distortion: firstly that induced by the proximity of a second rotor, and secondly that caused by non-zero inclination to the flight direction, as found at take-off. This requires significant extension of the previous axisymmetric analysis. We find that the introduction of asymmetric flow features can have a significant decibel effect on the radiated sound power. For instance, in low-speed conditions we find that the tonal level is reduced significantly by the proximity of a second rotor, compared to the axisymmetric case, while the effect on the broadband levels is rather modest.

Electron spin resonance of FeVO4

We report on electron spin resonance (ESR) investigations of a FeVO4 single crystal. Temperature and angular dependences of ESR resonance positions were measured and calculated in temperature range of 35–100 K. The spectra show rich angular dependences of the linewidth, the shape and the resonance field. They consist of a single broad line with asymmetric distortion. Due to the low symmetry of the crystal lattice this distortion can be explained by taking into account the influence of non diagonal dynamic susceptibility.

Structural study of nonlinear optical borates K1−xNaxSr4(BO3)3 (x≤0.5)

X-ray powder diffraction was used for the structural study of nonlinear optical borates K1−xNaxSr4(BO3)3 (x≤0.5). Results show that up to 50% K+ can be substituted by Na+ in orthorhombic K1−xNaxSr4(BO3)3. Isolated BO3 triangles in the Na-substituted compound constrict to adjust to a local distribution of alkali-metal atoms, which explains the large range of structural homogeneity. An expansion of the c axis in a unit cell with increasing Na substitution was found probably caused by the tilted BO3 triangles and asymmetric distortion of (K/Na)O8 polyhedra. As the ratio of ionic radii of alkaline-earth and alkali-metal cations decreases and the electronegative difference between alkaline-earth and alkali-metal cations increases, the crystal system of MM′4(BO3)3 borates changes from cubic to orthorhombic and then to monoclinic.