Columnar grain morphology and typical α texture transformed from a strong β //VD fiber texture are found in the Ti–6Al–4V alloy fabricated using electron beam rapid manufacturing (EBRM). This study ...mainly focused on the effect of the columnar grain morphology and the lamellar α orientation on the tensile damage behavior of the alloy. Samples in three different orientations were subjected to in-situ tensile tests. Results demonstrated that obvious anisotropic in-situ tensile behavior was presented in the alloy. Based on the columnar grain morphology and the β //VD fiber texture, we analyzed the crystallographic and spatial orientation characteristics of α lamellae in the alloy, discussed the effect of the columnar grain morphology, the crystallographic and spatial orientations of α lamellae on anisotropic in-situ tensile behaviors, and proposed that the crystallographic texture of α phase was a main factor inducing anisotropic tensile properties. In addition, the anisotropic fracture displacement was also associated with the spatial orientation of α laths.
•1, The alloy presented concentrated distribution on both the crystallographic and spatial orientation of α lamellae.•2, In-suit tensile behaviors were sensitive to the loading directions.•3, The anisotropic in-suit tensile behavior was due to the crystallographic and spatial orientation of α laths.
Cryptochromes are flavoproteins related to photolyases that are widespread throughout the plant and animal kingdom. They govern blue light-dependent growth in plants, control circadian rhythms in a ...light-dependent manner in invertebrates, and play a central part in the circadian clock in vertebrates. In addition, cryptochromes might function as receptors that allow animals to sense the Earth’s magnetic field. As cryptochromes are also present in mammals including humans, the possibility of a magnetosensitive protein is exciting. Here we attempt to provide a concise overview of cryptochromes in mammals. We briefly review their canonical role in the circadian rhythm from the molecular level to physiology, behaviour and diseases. We then discuss their disputed light sensitivity and proposed role in the magnetic sense in mammals, providing three mechanistic hypotheses. Specifically, mammalian cryptochromes could form light-induced radical pairs in particular cellular milieus, act as magnetoreceptors in darkness, or as secondary players in a magnetoreception signalling cascade. Future research can test these hypotheses to investigate if the role of mammalian cryptochromes extends beyond the circadian clock.
A robust algorithm based on cross-correlations and lucky imaging reliably allows the correction of spectrally diffused datasets. This step enables the resolution-limited analysis of the emission fine ...structure of semiconductor quantum dots (QDs). Bright and dark excitonic transitions are resolved with optimum signal-to-noise ratio, allowing for a precise determination of the angular direction of linear polarization of the different lines. The angular phases between polarization directions are intrinsically connected to the orientations of emission dipoles. This fact provides a tool for accurate numerical computation of the azimuth ϕ and polar angle θ of the QD with respect to the optical axis. Our in-situ characterization of QD fine structure and orientation represents a precise and non-invasive method without requiring specialized equipment beyond a standard luminescence setup. In this way, important information is provided whenever efficient coupling of a quantum emitter to the electromagnetic field is targeted by various nano- and micro-optic strategies.
Navigation requires coordination of egocentric and allocentric spatial reference frames and may involve vectorial computations relative to landmarks. Creation of a representation of target heading ...relative to landmarks could be accomplished from neurons that encode the conjunction of egocentric landmark bearings with allocentric head direction. Landmark vector representations could then be created by combining these cells with distance encoding cells. Landmark vector cells have been identified in rodent hippocampus. Given remembered vectors at goal locations, it would be possible to use such cells to compute trajectories to hidden goals. To look for the first stage in this process, we assessed parietal cortical neural activity as a function of egocentric cue light location and allocentric head direction in rats running a random sequence to light locations around a circular platform. We identified cells that exhibit the predicted egocentric-by-allocentric conjunctive characteristics and anticipate orienting toward the goal.
There are several models of the use of geometric and feature cues in reorientation (Cheng, Huttenlocher, & Newcombe, ). The adaptive combination approach posits that people integrate cues with ...weights that depend on cue salience and learning, or, when discrepancies are large, they choose between cues based on these variables (Cheng, Shettleworth, Huttenlocher, & Rieser, ; Newcombe & Huttenlocher, ). In a new paradigm designed to evaluate integration and choice, disoriented participants attempted to return to a heading direction, in a trapezoidal enclosure in which feature and geometric cues both unambiguously specified a heading, but later the feature was moved. With discrepancies greater than 90 degrees, participants choose geometry. With smaller discrepancies, integration appeared in three of five situations; otherwise, participants used geometry alone. Variation depended on direction of feature movement and whether the nearest corner was acute or obtuse. The results have implications for contrasting adaptive combination and modularity theory, and for future research, offering a new paradigm for reorientation research, and for testing cue integration more broadly.
This paper considers a mathematical description of the system of orientation and navigation of an underwater vehicle in middle and high latitudes using the Poisson equations. For the proposed ...mathematical description, a graphical application has been developed using the Qt cross-platform library, which allows you to determine the orientation and navigation parameters of an underwater vehicle.
The central complex (CX) in the brain of insects is a highly conserved group of midline‐spanning neuropils consisting of the upper and lower division of the central body, the protocerebral bridge, ...and the paired noduli. These neuropils are the substrate for a number of behaviors, most prominently goal‐oriented locomotion. Honeybees have been a model organism for sky‐compass orientation for more than 70 years, but there is still very limited knowledge about the structure and function of their CX. To advance and facilitate research on this brain area, we created a high‐resolution three‐dimensional atlas of the honeybee's CX and associated neuropils, including the posterior optic tubercles, the bulbs, and the anterior optic tubercles. To this end, we developed a modified version of the iterative shape averaging technique, which allowed us to achieve high volumetric accuracy of the neuropil models. For a finer definition of spatial locations within the central body, we defined layers based on immunostaining against the neuropeptides locustatachykinin, FMRFamide, gastrin/cholecystokinin, and allatostatin and included them into the atlas by elastic registration. Our honeybee CX atlas provides a platform for future neuroanatomical work.
The central complex in the brain of insects is a highly conserved group of midline‐spanning neuropils that houses the internal compass. It is responsible for goal‐directed locomotion and involved in the regulation of sleep‐wake cycles. Honeybees have been a model organism for sky‐compass orientation for more than 70 years, but there is still very limited knowledge about the structure and function of their central complex. We created a high‐resolution three‐dimensional atlas of the honeybee central complex and associated neuropils, which includes layers defined by the distribution of neuropeptidergic immunoreactivity. Our atlas provides a platform for future neuroanatomical work into the central complex of the honeybee.
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