Orientation Selectivity Research Articles

Development and organization of the retinal orientation selectivity map

Orientation or axial selectivity, the property of neurons in the visual system to respond preferentially to certain angles of visual stimuli, plays a pivotal role in our understanding of visual perception and information processing. This computation is performed as early as the retina, and although much work has established the cellular mechanisms of retinal orientation selectivity, how this computation is organized across the retina is unknown. Using a large dataset collected across the mouse retina, we demonstrate functional organization rules of retinal orientation selectivity. First, we identify three major functional classes of retinal cells that are orientation selective and match previous descriptions. Second, we show that one orientation is predominantly represented in the retina and that this predominant orientation changes as a function of retinal location. Third, we demonstrate that neural activity plays little role on the organization of retinal orientation selectivity. Lastly, we use in silico modeling followed by validation experiments to demonstrate that the overrepresented orientation aligns along concentric axes. These results demonstrate that, similar to direction selectivity, orientation selectivity is organized in a functional map as early as the retina.

Insight into Interfacial Heat Transfer of β-Ga2O3/Diamond Heterostructures via the Machine Learning Potential.

β-Ga2O3 is an ultrawide-band gap semiconductor with excellent potential for high-power and ultraviolet optoelectronic device applications. Low thermal conductivity is one of the major obstacles to enable the full performance of β-Ga2O3-based devices. A promising solution for this problem is to integrate β-Ga2O3 with a diamond heat sink. However, the thermal properties of the β-Ga2O3/diamond heterostructures after the interfacial bonding have not been studied extensively, which are influenced by the crystal orientations and interfacial atoms for the β-Ga2O3 and diamond interfaces. In this work, molecular dynamics simulations based on machine learning potential have been adopted to investigate the crystal-orientation-dependent and interfacial-atom-dependent thermal boundary resistance (TBR) of the β-Ga2O3/diamond heterostructure after interfacial bonding. The differences in TBR at different interfaces are explained in detail through the explorations of thermal conductivity value, thermal conductivity spectra, vibration density of states, and interfacial structures. Based on the above explorations, a further understanding of the influence of different crystal orientations and interfacial atoms on the β-Ga2O3/diamond heterostructure was achieved. Finally, insightful optimization strategies have been proposed in the study, which could pave the way for better thermal design and management of β-Ga2O3/diamond heterostructures according to guidance in the selection of the crystal orientations and interfacial atoms of the β-Ga2O3 and diamond interfaces.

Long-term intravital subcellular imaging with confocal scanning light-field microscopy.

Long-term observation of subcellular dynamics in living organisms is limited by background fluorescence originating from tissue scattering or dense labeling. Existing confocal approaches face an inevitable tradeoff among parallelization, resolution and phototoxicity. Here we present confocal scanning light-field microscopy (csLFM), which integrates axially elongated line-confocal illumination with the rolling shutter in scanning light-field microscopy (sLFM). csLFM enables high-fidelity, high-speed, three-dimensional (3D) imaging at near-diffraction-limit resolution with both optical sectioning and low phototoxicity. By simultaneous 3D excitation and detection, the excitation intensity can be reduced below 1 mW mm-2, with 15-fold higher signal-to-background ratio over sLFM. We imaged subcellular dynamics over 25,000 timeframes in optically challenging environments in different species, such as migrasome delivery in mouse spleen, retractosome generation in mouse liver and 3D voltage imaging in Drosophila. Moreover, csLFM facilitates high-fidelity, large-scale neural recording with reduced crosstalk, leading to high orientation selectivity to visual stimuli, similar to two-photon microscopy, which aids understanding of neural coding mechanisms.

Spin injection enhancement in CW VECSEL at room temperature using push-pull optical pumping.

We report the enhancement of spin injection efficiency in an external-cavity VCSEL based on a non-resonant pumping coupled with a polarized optical resonant illumination. This double pumping scheme allows both the injection of spin polarized electrons in the conduction band and the selection of the spin orientation for the electron/hole recombination laser process. Experimentally, a flip of the polarization state of the laser is achieved with an ellipticity of +31° (spin down) and -33° (spin up), so an increase of about 50% of the ellipticity is achieved in comparison to an optical non-resonant pumping alone.

Characterization and modulation of the unimolecular conformation of integrins with nanopore sensors

Integrins are a large family of heterodimeric mammalian transmembrane receptors that connect extracellular matrix (ECM) and the cytoskeleton. Integrin-mediated adhesion governs the cellular adhesion, mobility, and cell mechanobiology. Investigations on different integrins in cellular and the conformation change regulated by divalent metal ions and oligopeptides have been documented, they mainly adopted the cellular assays or surface manipulation to achieve the information of ensemble integrins with proteins and small molecules. This work presents the nanopore approach for the characterization of unimolecular integrin via resistive pulse sensing. The orientation selection in distinct nanopore in size and pH condition discloses the tiny disparity of the conformation and the local surface charge distribution. The divalent metal ions could efficiently modulate the conformation alteration of integrin, in which Ca2+ and Mn2+ could activate integrin αLβ2 to take larger physical dimension than Mg2+, and Ca2+ is superior to Mn2+ in the activation when integrin αLβ2 is treated in the mixed metal ions. The oligopeptide cRGD (cyclic Arg-Gly-Asp) and its derivatives cRGDfk and cRGDyk show specific binding with integrin αVβ3 and the complex of αVβ3-cRGD exhibits largest geometry upon Ca2+-mediation with characteristic nanopore translocation feature. This work provides a platform for unimolecular integrin sensing and the modulation of the local conformation transition regulated by divalent metal ions and oligopeptides, which will be valuable for the representation of integrin-related cellular behavior and bio-function.

C(sp)-C(sp) Lever-Based Targets of Orientational Chirality: Design and Asymmetric Synthesis.

In this study, the design and asymmetric synthesis of a series of chiral targets of orientational chirality were conducted by taking advantage of N-sulfinylimine-assisted nucleophilic addition and modified Sonogashira catalytic coupling systems. Orientational isomers were controlled completely using alkynyl/alkynyl levers [C(sp)-C(sp) axis] with absolute configuration assignment determined by X-ray structural analysis. The key structural element of the resulting orientational chirality is uniquely characterized by remote through-space blocking. Forty examples of multi-step synthesis were performed, with modest to good yields and excellent orientational selectivity. Several chiral orientational amino targets are attached with scaffolds of natural and medicinal products, showing potential pharmaceutical and medical applications in the future.

Influence of building orientation and thermal mass configuration on the prediction of Natural Ventilation Potential (NVP) of various climates of India.

Natural ventilation potential (NVP) of a climate is a theoretical basis, and it gains importance due to the promising need for building energy conservation while conceding required thermal comfort conditions. A modified NVP analytical model is proposed by considering parameters involved in the earlier models (Yang et al., Build Environ 40:738-746, 2005; Luo et al., Build Environ 42:2289-2298, 2007). The effect of the dynamic thermal behavior of the wall/roof and building orientation on the indoor air temperature has been evaluated. The analytical model is applied to 11 major cities of India that belong to composite, hot-dry, temperate, and warm-humid climates. Five different envelope configurations are analyzed to envisage the NVP of concern climate (ED-I to ED-V). The results show that the effect of dynamic thermal response factors on the NVP is significant, and optimization of thermal response factors in addition to the U-value is mandatory. The impact of wind frequency on the selection of building orientation is substantial since it influences the total heat gained by the building envelope. Moreover, it is perceived that the optimum building orientation is independent of the climate and weather conditions. ED-II and ED-III are energy-efficient envelopes for composite, temperate, warm-humid, and hot-dry climates. The results revealed that the Mumbai climate has the highest NVP of 66% while the building is oriented in an E-W direction, and the lowest is observed for Jodhpur, i.e., 44% of the year when the building is in the NE-SW direction. The model helps the building architectural designers envisage the true NVP and assess the suitability of the building for natural ventilation.

Development of lightweight and high-strength glass fiber and natural fiber hybrid composites using VARTM technique

This research paper presents the synthesis of Glass Fiber Reinforced Plastic (GFRP) and Natural Fiber Hybrid Composites (NFHC) utilizing Vacuum-Assisted Resin Transfer Molding (VARTM) techniques. Jute and flax fibers were strategically selected for their unique properties and potential synergistic effects when combined with glass fibers. The study systematically evaluates the influence of natural fiber incorporation on the mechanical performance of the composites, focusing on critical factors such as fiber type, orientation, and resin selection. A series of meticulously crafted laminate configurations were employed. These included combinations of glass and jute fibers (GJG, GJGJG), glass and flax fibers (GFG, GFGFG), and a reference laminate composed solely of glass fibers (GGGGG). The mechanical characterization involved rigorous Izod impact testing, hardness assessments, and water absorption tests to provide a detailed understanding of behavior of composite material. The results reveal that the incorporation of jute fibers resulted in a significant enhancement of impact resistance of up to 59 % compared to GFG laminates and hardness. Water absorption varied across the laminates, with GGGGG exhibiting the lowest value of 0.054 %. Scanning Electron Microscopy (SEM) was employed to gain valuable insights into the critical fiber-matrix interaction and microstructure of the composites, further elucidating the observed mechanical properties. These findings pave the way for lightweight, high-strength composites ideal for engineering applications, particularly automotive mono leaf springs. The resulting weight reduction promises significant gains in fuel efficiency and vehicle performance, advancing sustainable materials with exceptional mechanics.

Mapping the roles of scan strategy and build orientation in predicting the crystallographic texture and yield strength of 316L stainless steel produced by laser powder bed fusion

Laser Powder Bed Fusion (L-PBF) has emerged as a leading additive manufacturing (AM) technique for manufacturing complex metal parts, with 316L stainless steel being favored for its exceptional corrosion resistance and mechanical properties. While previous studies have explored the effects of different scan strategies and build orientations on the microstructure and room temperature tensile properties of L-PBF printed 316L stainless steel, there is still a lack of a comprehensive predictive model that accurately captures the combined effects of these process parameters on the final crystallographic texture and tensile properties. This study presents a novel approach that establishes a direct correlation between process parameters, microstructure, and mechanical behavior by modeling the influence of scan strategy rotation angles and build orientations on the crystallographic texture of L-PBF-manufactured 316L stainless steel. To validate the model, a series of samples were fabricated using various scan strategy rotation angles and build orientations, enabling detailed microstructural analysis and mechanical testing. The findings demonstrate a direct relationship between the selected process parameters and the resulting mechanical properties, underscoring the importance of scan strategy and build orientation selection on mechanical response. Furthermore, our calibrated model exhibits high predictive accuracy as validated through a comparison with experimental data.

Sequential selection and calibration of video frames for 3D outdoor scene reconstruction

Abstract3D scene understanding and reconstruction aims to obtain a concise scene representation from images and reconstruct the complete scene, including the scene layout, objects bounding boxes and shapes. Existing holistic scene understanding methods primarily recover scenes from single images, with a focus on indoor scenes. Due to the complexity of real‐world, the information provided by a single image is limited, resulting in issues such as object occlusion and omission. Furthermore, captured data from outdoor scenes exhibits characteristics of sparsity, strong temporal dependencies and a lack of annotations. Consequently, the task of understanding and reconstructing outdoor scenes is highly challenging. The authors propose a sparse multi‐view images‐based 3D scene reconstruction framework (SMSR). It divides the scene reconstruction task into three stages: initial prediction, refinement, and fusion stage. The first two stages extract 3D scene representations from each viewpoint, while the final stage involves selection, calibration and fusion of object positions and orientations across different viewpoints. SMSR effectively address the issue of object omission by utilizing small‐scale sequential scene information. Experimental results on the general outdoor scene dataset UrbanScene3D‐Art Sci and our proprietary dataset Software College Aerial Time‐series Images, demonstrate that SMSR achieves superior performance in the scene understanding and reconstruction.

Stimulus encoding by specific inactivation of cortical neurons

Neuronal ensembles are groups of neurons with correlated activity associated with sensory, motor, and behavioral functions. To explore how ensembles encode information, we investigated responses of visual cortical neurons in awake mice using volumetric two-photon calcium imaging during visual stimulation. We identified neuronal ensembles employing an unsupervised model-free algorithm and, besides neurons activated by the visual stimulus (termed “onsemble”), we also find neurons that are specifically inactivated (termed “offsemble”). Offsemble neurons showed faster calcium decay during stimuli, suggesting selective inhibition. In response to visual stimuli, each ensemble (onsemble+offsemble) exhibited small trial-to-trial variability, high orientation selectivity, and superior predictive accuracy for visual stimulus orientation, surpassing the sum of individual neuron activity. Thus, the combined selective activation and inactivation of cortical neurons enhances visual encoding as an emergent and distributed neural code.

Design and Asymmetric Control of Orientational Chirality by Using the Combination of C(sp2)-C(sp) Levers and Achiral N-Protecting Group.

New chiral targets of orientational chirality have been designed and asymmetrically synthesized by taking advantage of N-sulfinyl imine-directed nucleophilic addition/oxidation, Suzuki-Miyaura, and Sonogashira cross-coupling reactions. Orientation of single isomers has been selectively controlled by using aryl/alkynyl levers [C(sp2)-C(sp) axis] and tBuSO2- protecting group on nitrogen as proven by X-ray diffraction analysis. The key structural characteristic of resulting orientational products is shown by remote through-space blocking manner. Seventeen examples of multi-step synthesis were obtained with modest to good chemical yields and complete orientational selectivity.

Visual Corticotectal Neurons in Awake Rabbits: Receptive Fields and Driving Monosynaptic Thalamocortical Inputs.

The superior colliculus receives powerful synaptic inputs from corticotectal neurons in the visual cortex. The function of these corticotectal neurons remains largely unknown due to a limited understanding of their response properties and connectivity. Here, we use antidromic methods to identify corticotectal neurons in awake male and female rabbits, and measure their axonal conduction times, thalamic inputs and receptive field properties. All corticotectal neurons responded to sinusoidal drifting gratings with a nonlinear (nonsinusoidal) increase in mean firing rate but showed pronounced differences in their ON-OFF receptive field structures that we classified into three groups, Cx, S2, and S1. Cx receptive fields had highly overlapping ON and OFF subfields as classical complex cells, S2 had largely separated ON and OFF subfields as classical simple cells, and S1 had a single ON or OFF subfield. Thus, all corticotectal neurons are homogeneous in their nonlinear spatial summation but very heterogeneous in their spatial integration of ON and OFF inputs. The Cx type had the fastest conducting axons, the highest spontaneous activity, and the strongest and fastest visual responses. The S2 type had the highest orientation selectivity, and the S1 type had the slowest conducting axons. Moreover, our cross-correlation analyses found that a subpopulation of corticotectal neurons with very fast conducting axons and high spontaneous firing rates (largely "Cx" type) receives monosynaptic input from retinotopically aligned thalamic neurons. This previously unrecognized fast-conducting thalamic-mediated corticotectal pathway may provide specialized information to superior colliculus and prime recipient neurons for subsequent corticotectal or retinal synaptic input.

Curriculum integration: The case of social sciences and pre-vocational education textbooks

Curriculum materials are integrated horizontally, connecting various curricula by demonstrating concepts, principles, and laws to contribute to a comprehensive understanding and sustainability of the learned material. This approach is valid in the case of the National and Civic Education (NCE) curriculum, which can assist in overcoming the vital issues of vocational orientation in Jordan. This study aimed to explore whether the NCE curriculum contextualizes vocational education concepts facilitating students’ right selection of career paths and orientations. The researchers analyzed three NCE textbooks (8th, 9th, and 10th grades) to determine whether these textbooks included concepts relevant to vocational education and vocational guidance. The results showed that (NCE) textbooks include some valuable concepts; however, there is an absence of key concepts related to vocational education orientation and vocational guidance. The study concluded that NCE textbooks in upper primary education include essential concepts that could be out of interest to the students; however, the textbook can be integrated with more concepts to support students’ knowledge of vocational and technical education.

Grain growth competition and formation of grain boundaries during solidification of hcp alloys

Grain growth competition during directional solidification of a polycrystal with hexagonal (hcp) symmetry (Mg-1wt%Gd alloy) is studied by phase-field modeling, exploring the effect of the temperature gradient G on the resulting grain boundary (GB) orientation selection. Results show that selection mechanisms and scaling laws derived for cubic (fcc, bcc) crystals also apply to hcp materials (within their basal plane), provided a re-estimation of fitting parameters and re-scaling to account for the sixfold symmetry. While grain growth competition remains stochastic with rare events of unexpected elimination or side-branching along the developing GBs, we also confirm an overall transition from a geometrical limit to a favorably oriented grain limit behavior with an increase of thermal gradient within the dendritic regime, and the progressive alignment of dendrites and GBs toward the temperature gradient direction with an increase of G during the dendritic-to-cellular morphological transition. Comparisons with original thin-sample directional solidification experiments show a qualitative agreement with PF results, yet with notable discrepancies, which nonetheless can be explained based on the stochastic variability of selected GB orientations, and the statistically limited experimental sample size. Overall, our results extend the understanding of GB formation and grain growth competition during solidification of hcp materials, and the effect of thermal conditions, nonetheless concluding on the challenges of extending the current studies to three dimensions, and the need for much broader (statistically significant) data sets of GB orientation selected under well-identified solidification conditions.

Root microbiota analysis of Oryza rufipogon and Oryza sativa reveals an orientation selection during the domestication process.

The root-associated microbiota has a close relation to the life activities of plants, and its composition is affected by the rhizospheric environment and plant genotypes. Rice (Oryza sativa) was domesticated from the ancestor species Oryza rufipogon. Many important agricultural traits and adversity resistance of rice have changed during a long time of natural domestication and artificial selection. However, the influence of rice genotypes on root microbiota in important agricultural traits remains to be explained. In this study, we performed 16S rRNA and internal transcribed spacer (ITS) gene amplicon sequencing to generate bacterial and fungal community profiles of O. rufipogon and O. sativa, both of which were planted in a farm in Guangzhou and had reached the reproductive stage. We compared their root microbiota in detail by alpha diversity, beta diversity, different species, core microbiota, and correlation analyses. We found that the relative abundance of bacteria was significantly higher in the cultivated rice than in the common wild rice, while the relative abundance of fungi was the opposite. Significant differences in agricultural traits between O. rufipogon and O. sativa showed a high correlation with core microorganisms in the two Oryza species, which only existed in either or had obviously different abundance in both two species, indicating that rice genotype/phenotype had a strong influence on recruiting specific microorganisms. Our study provides a theoretical basis for the in-depth understanding of rice root microbiota and the improvement of rice breeding from the perspective of the interaction between root microorganisms and plants.IMPORTANCEPlant root microorganisms play a vital role not only in plant growth and development but also in responding the biotic and abiotic stresses. Oryza sativa is domesticated from Oryza rufipogon which has many excellent agricultural traits especially containing resistance to biotic and abiotic stresses. To improve the yield and resistance of cultivated rice, it is particularly important to deeply research on differences between O. sativa and O. rufipogon and find beneficial microorganisms to remodel the root microbiome of O. sativa.

Gradient Transformation of the Double Gyroid to the Double Diamond in Soft Matter.

Transitions between gyroid and diamond intercatenated double network phases occur in many types of soft matter, but to date, the structural pathway and the crystallographic relationships remain unclear. Slice and view scanning electron microscopy tomography of a diblock copolymer affords monitoring of the evolving shape of the intermaterial dividing surface, allowing structural characterization of both the majority and minority domains. Two trihedral malleable mesoatoms combine to form a single tetrahedral mesoatom in a volume additive manner while preserving network topology, as the types of loops, the number of mesoatoms in a loop, minority domain strut lengths, and directions that connect a given mesoatom to its neighbors evolve across a 150 nm wide transition zone (TZ). The [111]DD direction is coincident with the [110]DG direction so that the (111)DD and (110)DG planes define the boundaries of the TZ. Selection of the particular crystal orientations and direction and width of the transition zone is to minimize the cost of morphing the mesoatoms from one structure to the other, by maximizing like-block continuity and minimizing the variation of the surface curvature and thickness of the domains across the TZ. Such coherent continuity of the independent, intercatenated networks across the transition zone is critical for applications such as graded mechanical trusses where the pair of different networks are joined to provide different mechanical properties for adjacent grains or could serve as a nanoscale anode/cathode allowing super charging and discharging provided the networks are continuous and rigorously separate.

Experimental assessment of blowing effect on vehicle performance and aero-acoustics in small-rotor/wing interaction

The tiltrotor design for urban air mobility (UAM) combines vertical take-off and landing (VTOL) capability with fixed-wing efficiency. However, it confronts challenges posed by downward force due to rotor wake effect. Previous research has employed active flow control, such as blowing air, primarily during forward flight using a single air outlet slot. However, the implications for rotor performance and aero-acoustic characteristics have remained unexplored. The experimental approach in this study involves controlled blowing air with moderate momentum in hover mode, concentrating on rotor performance, download force, noise signature, and the influence of port patterns. It is found that the radial port pattern emerges as pivotal for mitigating downward force and augmenting rotor efficiency. The efficacy of noise reduction hinges on both receiver orientation and port pattern selection. This investigation significantly contributes to understanding the role of blowing effect in optimizing tiltrotor designs, particularly in the context of rotor wake-wing interaction.

Sodium alginate/ diatom -based blotting hydrogel material for Pb(II) removal: Effect of crosslinker optimization on its composition, selectivity, and desorption rate

In this study, we report a novel adsorption material (SAD-IIP), which is used for the directional adsorption of Pb (II), the polymerization time, the amount of crosslinking agent and the crosslinking time were optimized by response surface design, and the effect of the amount of crosslinking agent on the adsorption of lead on SAD-IIP was analyzed. The numerical control of cross-linking agent directly determines the number of effective imprinting sites, which affects the orientation selectivity of target ions and the desorption rate of the adsorbent. The results showed that the best adsorption performance was obtained when the polymerization temperature was 59.14 ° C, the amount of glutaraldehyde was 1.20 ml, and the crosslinking time was 92.55 min. The adsorption amount and imprinting factor were 244.09 mg/G and 9.90, respectively, the self-polymerization and self-crosslinking of the adsorbent in the imprinting process are effectively avoided. The adsorption mechanism of SAD-IIP is ion exchange with Ca2+ and chelation coordination of sulfhydryl, hydroxy, carboxyl with lead ion. After 10 cycles, the removal rate of Pb (II) and desorption rate of SAD-IIP were 92.75% and 70.43%, respectively. These results indicate that the rational control of the introduction conditions of cross-linking agent is of theoretical and practical value for the preparation of new hydrogel imprinting materials for selective adsorption of target ions and efficient recovery of Pb (II).

Retinal origin of orientation but not direction selective maps in the superior colliculus

Neurons in the mouse superior colliculus ("colliculus") are arranged in ordered spatial maps. While orientation-selective (OS) neurons form a concentric map aligned to the center of vision, direction-selective (DS) neurons are arranged in patches with changing preferences across the visual field. It remains unclear whether these maps are a consequence of feedforward input from the retina or local computations in the colliculus. To determine whether these maps originate in the retina, we mapped the local and global distribution of OS and DS retinal ganglion cell axon boutons using invivo two-photon calcium imaging. We found that OS boutons formed patches that matched the distribution of OS neurons within the colliculus. DS boutons displayed fewer regional specializations, better reflecting the organization of DS neurons in the retina. Both eyes convey similar orientation but different DS inputs to the colliculus, as shown in recordings from retinal explants. These data demonstrate that orientation and direction maps within the colliculus are independent, where orientation maps are likely inherited from the retina, but direction maps require additional computations.