Orientation-dependent Features Research Articles

Classification of behaviors of free-ranging cattle using accelerometry signatures collected by virtual fence collars

Precision farming technology, including GPS collars with biologging, has revolutionized remote livestock monitoring in extensive grazing systems. High resolution accelerometry can be used to infer the behavior of an animal. Previous behavioral classification studies using accelerometer data have focused on a few key behaviors and were mostly conducted in controlled situations. Here, we conducted behavioral observations of 38 beef cows (Hereford, Limousine, Charolais, Simmental/NRF/Hereford mix) free-ranging in rugged, forested areas, and fitted with a commercially available virtual fence collar (Nofence) containing a 10Hz tri-axial accelerometer. We used random forest models to calibrate data from the accelerometers on both commonly documented (e.g., feeding, resting, walking) and rarer (e.g., scratching, head butting, self-grooming) behaviors. Our goal was to assess pre-processing decisions including different running mean intervals (smoothing window of 1, 5, or 20 seconds), collar orientation and feature selection (orientation-dependent versus orientation-independent features). We identified the 10 most common behaviors exhibited by the cows. Models based only on orientation-independent features did not perform better than models based on orientation-dependent features, despite variation in how collars were attached (direction and tightness). Using a 20 seconds running mean and orientation-dependent features resulted in the highest model performance (model accuracy: 0.998, precision: 0.991, and recall: 0.989). We also used this model to add 11 rarer behaviors (each< 0.1% of the data; e.g. head butting, throwing head, self-grooming). These rarer behaviors were predicted with less accuracy because they were not observed at all for some individuals, but overall model performance remained high (accuracy, precision, recall >98%). Our study suggests that the accelerometers in the Nofence collars are suitable to identify the most common behaviors of free-ranging cattle. The results of this study could be used in future research for understanding cattle habitat selection in rugged forest ranges, herd dynamics, or responses to stressors such as carnivores, as well as to improve cattle management and welfare.

Polarization-resolved analysis of high-order harmonic generation in monolayer MoS2

We employ a theoretical model based on the density-matrix equation in the velocity gauge to calculate high harmonic generation from monolayer MoS2. This approach incorporates the tight-binding model, enabling the full consideration of both crystal symmetry and multiple band effects. In additional to the usual odd harmonics, even harmonics are also presented in the case of observing two different polarization components, which are parallel and perpendicular to the polarization of linearly driving pulses. We detailedly analyze the crystal orientation dependence for the parallel and perpendicular components of both odd- and even-harmonics. It is found that they exhibits different modulation behavior with rotating the crystal orientation. The simulation results capture all important orientation-dependent features observed in the recent experiment, thus demonstrating that the Berry curvature of MoS2 has been appropriately considered in our proposed model. In order to facilitate analysis of the underlying mechanism, we examine the channel current in terms of the contribution from different density-matrix elements, and identify their role in the orientation modulation of high harmonics. We further use simplified one-dimensional integral model to explain the appearance of perpendicular components of even harmonics. Our analysis shows that the multi-band coupling effect is the origin of the parallel even harmonics, while the broken inversion symmetry of phase difference of momentum matrix elements along two orthogonal directions determines the perpendicular even harmonic generation. Additionally, the relationship between the concept of Berry curvature and our theoretical framework is discussed. These demonstrations show that polarization-resolved high harmonics might provide an all-optical way for imaging material’s Berry curvature.

Pigeons spontaneously form three-dimensional shape categories

We explored the pigeon’s representation of the shape of simple three-dimensional objects (geons) rotated in depth (four views each of four geons). Pigeons assigned to the Categorization group had to respond differentially to images of four different geons—termed arch, barrel, brick, and wedge—based on their 3D shape, regardless of the orientation of the object. Pigeons assigned to the Pseudocategorization group had to respond differentially to the same objects based on groupings that did not correspond to object identity, which required the learning of local orientation-dependent features (e.g., a concave curve on top, or the position of an illumination hotspot). The Categorization group, which could employ object-identity representations, quickly achieved highly accurate responding. The Pseudocategorization group, however, failed to achieve reliable above-chance responding. In addition, the reaction times for the Categorization group were significantly shorter than for the Pseudocategorization group. These results indicate that pigeons show a strong, spontaneous tendency to categorize the shapes of different orientations in depth of the same 3D object as similar, if not equivalent; they do so despite the vast differences in image characteristics caused by the variations in orientations, even when such categorization is contrary to the reinforcement contingencies.

Orientation-dependent deformation mechanisms of bcc niobium nanoparticles

Nanoparticles usually exhibit pronounced anisotropic properties, and a close insight into the atomic-scale deformation mechanisms is of great interest. In present study, atomic simulations are conducted to analyse the compression of bcc nanoparticles, and orientation-dependent features are addressed. It is revealed that surface morphology under indenter predominantly governs the initial elastic response. The loading curve follows the flat punch contact model in [1 1 0] compression, while it obeys the Hertzian contact model in [1 1 1] and [0 0 1] compressions. In plastic deformation regime, full dislocation gliding is dominated in [1 1 0] compression, while deformation twinning is prominent in [1 1 1] compression, and these two mechanisms coexist in [0 0 1] compression. Such deformation mechanisms are distinct from those in bulk crystals under nanoindentation and nanopillars under compression, and the major differences are also illuminated. Our results provide an atomic perspective on the mechanical behaviours of bcc nanoparticles and are helpful for the design of nanoparticle-based components and systems.

Raman Spectra of Shock Compressed Pentaerythritol Tetranitrate Single Crystals: Anisotropic Response

To gain insight into the anisotropic sensitivity of shocked pentaerythritol tetranitrate (PETN) single crystals, single-pulse Raman spectroscopy was used to examine the response of crystals shocked along the [100] (insensitive) and [110] (sensitive) orientations. High-resolution Raman spectra revealed several orientation-dependent features under shock compression: (i) substantially different stress dependence of the Raman shift for the CH(2) and NO(2) stretching modes for the two orientations, (ii) discontinuity in the stress dependence of the Raman shift for the CH(2) stretching modes above 4 GPa for the [110] orientation, and (iii) large broadening for the CH(2) and NO(2) asymmetric stretching modes for stresses above 4 GPa for the [110] orientation. The present data in combination with previous static pressure results provide support for conformational changes in PETN molecules for shock compression along the [110] (sensitive) orientation. Implications of the present results for the anisotropic sensitivity of shocked PETN are discussed.

Molecular pair potential of chiral amino acid amphiphile in Langmuir monolayers on the basis of an atomistic model

In the present work, the pair potential of enantiomeric N-palmitoyl aspartic acid amphiphile monolayer at the air/water interface is calculated based on an atomistic model. The molecular structure and partial charges are calculated using two semi empirical (PM3, AM1) and one empirical (Gasteiger and Marcili) methods. A distance-dependent dielectric function is used to represent the interfacial dielectric constant at the aqueous subphase. The present study indicates that a pair of molecules have favorable interaction at specific ranges of mutual orientations. Other orientations are favorable but at larger separations. Favorable electrostatic interaction at a specific combination of orientation and short separations of the head groups significantly contribute to the total energy. The curvature of the domain boundary is suggested to be driven by the favorable arrangement which is dependent on the pair potential of molecules. The use of charges obtained by the PM3 and GM do not lead to a significant variation of the orientation-dependent features, while the AM1 predicts higher partial charges and interactions are stronger than the former two methods. However, orientation-dependent features remain the same. The variations in the LJ parameters and charges indicate that the conclusions made are insensitive to the choice of parameters. The mutual favorable interaction predicted by calculation agree with the handedness of curvature of domains.

Fe XANES spectra of iron-rich micas

Fe-rich mica crystals have been studied using microbeam XANES spectroscopy of the Fe K edges in order to evaluate the dependence of XANES features and resultant Fe 3+ /σFe values on the orientation of the crystals with respect to the polarization of the synchrotron beam. Polished, thinned samples were prepared with cleavages perpendicular to the plane of their thin sections, and these sections were then rotated relative to the horizontal plane of the ring and the 10 × 15 μm beam. Results show that both pre-edge and main-edge features in these micas exhibit orientation-dependent changes in both peak intensity and energy. These shifts constitute the majority of the error (∼ ± 10%) in determinations of Fe 3+ /σFe by pre-edge energy, a problem that will be overcome in future work through techniques for quantification of grain orientations. Results show distinctive orientation-dependent features in the main edge region, from which it will soon be possible to deconvolute contributions from multiple scattering interactions to obtain information about the electronic properties of micas. Data also demonstrate the exciting potential of XANES pre-edge spectroscopy for routine, in situ analyses of Fe 3+ /σFe on comparable scales to electron microprobe analyses.

Polarized XANES of Co(III)(NH3)6 molecular crystals

Polarized single crystal x-ray absorption spectra have been measured for Co(NH,) (ClO,),Cl:KCl. These spectra show pronounced orientation dependence fior several features on the high energy side of the Co K absorption edge. The Co in this salt has a tri onally distorted octahedral structure with N-Co-N angles of 89.5O and 90.5 8 , hence first shell scatterers cannot account for the observed orientation dependence. As we show below, the orientation dependent features can be interpreted in terms of a singlescattering EXAFS model involvin hydrogen-bonded to the Co(NH,), & scattering from a perchlorate which is ion. Co(NH,),(ClO.,),Cl:KCl was prepared by the method of Wilson and Solomon [l] and smgle crystals were oriented by standard diffraction methods. In initial experiments, the Co(NH3)03+ molecules were oriented so that both the propagation (k) and polarization (e) vectors were contained in one of the CoN4 planes. The crystal was rotated about e *k and XANES spectra were measured every 15 degrees for a total of thirteen different orientations of e. In a second experiment, the polarization vector was oriented either parallel or perpendicular to the crystallographic 3-fold axis. In order to compare different orientations it was necessary to develop a procedure for the precise, reproducible normalization of experimental XANES spectra. In brief, this method 121 involves subtraction of a low order polynomial from the data followed by multiplication by a scale factor. The polynomial and scale factor are adjusted to maximize the agreement, both below and above the edge, with tabulated x-ray absorption cross section.