Orbital Convergence Research Articles

Weaker forms of specification for maps on uniform spaces

We introduce and study here some weaker forms of specification property for uniformly continuous surjective self-maps on uniform spaces, namely topological quasi-weak specification property, topological semi-weak specification property and topological periodic quasi-weak specification property. We also introduce and study the notion of topological specification point for uniformly continuous surjective self-maps on uniform spaces. It is proved that for uniformly continuous surjective self-maps on uniform spaces the pointwise topological periodic specification property implies Devaney chaos. Moreover, the relation between pointwise notions of mixing, topological shadowing and topological specification is explored. It is shown that for uniformly continuous self-maps on uniform spaces the existence of two distinct topological specification points implies that the map has positive uniform entropy. Also, the limiting behaviour of a topological specification point under orbital convergence of maps is studied.

Endonasal Endoscopic Anatomy of the Orbito-Cavernous-Pterygopalatine Interface: Multilayer Anatomical Description and Landmarks to Define the Limits of the Compartments

Despite growing interest in the endoscopic endonasal approach (EEA) to the medial orbital apex (OA), a comprehensive description of the multilayer topology lying at the intersection of the regional compartments is missing. An EEA to the OA, pterygopalatine fossa, and cavernous sinus was performed in 20 specimens. A 360° layer-by-layer dissection was performed taking into consideration relevant anatomical aspects of the interface and documented with 3-dimensional technologies. Endoscopic landmarks were analyzed to provide an outline of the compartments and identify critical structures. Additionally, the consistency of a previously described reference called orbital apex convergence prominence was analyzed and a method to identify its position was introduced. The orbital apex convergence prominence was an inconsistent finding (15%). However, a craniometric method introduced in this study proved to be reliable to reach the orbital apex convergence point. Additional structures such as the sphenoethmoidal suture and a 3-suture junction (sphenoethmoidal-palatoethmoidal-palatosphenoidal) helped to identify the posterior limit of the OA and define a keyhole to access the compartments of the interface. We defined the bone limits of the "optic risk zone," an area where the optic nerve is more susceptible to damage. Furthermore, an orbital fusion line (periorbita-dura-periosteum) was identified and divided into 4 segments according to adjacent structures: optic, cavernous, pterygopalatine, and infraorbital. Understanding cranial landmarks and the folds of the layers covering the orbito-cavernous-pterygopalatine interface can facilitate tailoring an EEA to the medial orbital space and avoid unnecessary exposure of sensitive anatomy in the vicinity.

Seeing through the eyes of the sabertooth Thylacosmilus atrox (Metatheria, Sparassodonta)

The evolution of mammalian vision is difficult to study because the actual receptor organs—the eyes—are not preserved in the fossil record. Orbital orientation and size are the traditional proxies for inferring aspects of ocular function, such as stereoscopy. Adaptations for good stereopsis have evolved in living predaceous mammals, and it is reasonable to infer that fossil representatives would follow the same pattern. This applies to the sparassodonts, an extinct group of South American hypercarnivores related to marsupials, with one exception. In the sabertooth Thylacosmilus atrox, the bony orbits were notably divergent, like those of a cow or a horse, and thus radically differing from conditions in any other known mammalian predator. Orbital convergence alone, however, does not determine presence of stereopsis; frontation and verticality of the orbits also play a role. We show that the orbits of Thylacosmilus were frontated and verticalized in a way that favored some degree of stereopsis and compensated for limited convergence in orbital orientation. The forcing function behind these morphological tradeoffs was the extraordinary growth of its rootless canines, which affected skull shape in Thylacosmilus in numerous ways, including relative orbital displacement.

Ambush predation and the origin of euprimates.

Primates of modern aspect (euprimates) are characterized by a suite of characteristics (e.g., convergent orbits, grasping hands and feet, reduced claws, and leaping), but the selective pressures responsible for the evolution of these euprimate characteristics have long remained controversial. Here, we used a molecular phyloecological approach to determine the diet of the common ancestor of living primates (CALP), and the results showed that the CALP had increased carnivory. Given the carnivory of the CALP, along with the general observation that orbital convergence is largely restricted to ambush predators, our study suggests that the euprimate characteristics could have been more specifically adapted for ambush predation. In particular, our behavior experiment further shows that nonclaw climbing can significantly reduce noises, which could benefit the ancestral euprimates’ stalking to ambush their prey in trees. Therefore, our study suggests that the distinctive euprimate characteristics may have evolved as their specialized adaptation for ambush predation in arboreal environments.

Extremely young asteroid pair (458271) 2010 UM26 and 2010 RN221

Aims. The extremely similar heliocentric orbital elements of the main-belt objects (458271) 2010 UM26 and 2010 RN221 make them the tightest known pair and hold the promise that it is very young. We analyzed the conditions of its origin and determined its age. Methods. We conducted dedicated observations of (458271) 2010 UM26 and 2010 RN221 in summer 2022 that resulted in a high-accuracy astrometric set of data. Joining them with the previously available observations, we improved the precision of the orbit determination of both asteroids. We used numerical simulations backward in time to constrain the origin of this new pair by observing orbital convergence in Cartesian space. Results. Using a large number of possible clone variants of (458271) 2010 UM26 and 2010 RN221, we find that they all converge in a narrow time interval around March 2003. They have extremely tight minimum distances (≤1000 km) and minimum relative velocities (≤3 cm s−1). These conditions require that the mutual gravitational attraction of the asteroids constituting the pair is included when its age is determined. Extending our model by this effect even improves the convergence results. We find a probability of more than 55% that the pair formed after 2000. However, quasi-satellite captures mean that the possible age uncertainty of this pair might extend to the 1960s. This is by far the youngest known asteroid pair, however. It is a prime target for future astronomical observations.

Follow Your Nose: Ontogeny of the Olfactory Duct in Primates

Most primates are characterized by orbital convergence, the displacement of the orbits toward the rostral midline. In platyrrhine primates and tarsiers, this convergence is so extreme that orbits meet in the midline at the apical interorbital septum. This produces a spatial separation of the anterior cranial fossa and the nasal cavity. The olfactory bulbs of the brain pass dorsal and then rostral to the orbits to reach the nasal cavity via a bony tube, the olfactory duct. Nerves are expected to constrain growth of musculoskeletal structures. We hypothesized that the network of olfactory nerves effectively tethers the olfactory bulbs to the mucosa of the nasal cavity, and the growth of facial structures in these primates results in rostral displacement of the olfactory bulbs through ontogeny. In addition, growth of the midface may be constrained by this functional relationship.This comparative analysis was based on 3D reconstructions of cranial structures in newborns and adults from representative platyrrhine species (e.g., Aotus nancymaae and Cebuella pygmaea) and tarsiers (Tarsius syrichta). Spatial relationships of the olfactory duct were estimated using endocasts based on conventional microCT scans. In addition, diffusion iodine contrast‐enhanced CT (diceCT) images were used to study Aotus nancymaae at multiple stages of ontogeny. DiceCT allowed us to reconstruct the actual position of olfactory bulbs relative to the olfactory duct and the distribution of olfactory nerves in the nasal cavity. 3DSlicer and Blender software were used to render 3D models. These data confirm our hypothesis that the rostral projection of the olfactory bulbs relative to the frontal lobes of the brain increases through ontogeny. In addition, the paths of olfactory nerves are diverted around the convergent eyes. The ontogenetic relationships occurring in platyrrhine and tarsier olfactory ducts have evolutionary implications for biological variation in the primate skull.

Simultaneous Endoscopic Endonasal Decompression of the Optic Canal, Superior Orbital Fissure, and Proper Orbital Apex for Traumatic Orbital Apex Syndrome: Surgical Anatomy and Technical Note.

ObjectivesTraumatic orbital apex syndrome (TOAS) is an uncommon but severe ocular complication of craniomaxillofacial fracture. The optimal surgical strategy for TOAS has not been determined. To investigate the endoscopic anatomy of the orbital apex region, propose a protocol for simultaneous endoscopic endonasal decompression of the optic canal, superior orbital fissure, and proper orbital apex (EEDCFA) for TOAS and report its use in two patients.MethodsAn endoscopic endonasal approach was utilized to dissect the orbital apex region in two silicon-injected adult cadaveric heads. The details of the procedure used for decompression of the orbital apex were determined. The effects of this procedure were determined in two patients with TOAS who underwent simultaneous decompression of the optic canal, superior orbital fissure, and proper orbital apex.ResultsThe orbital apex consisted of three portions, the contents of the optic canal superomedially; the contents of the superior orbital fissure inferolaterally; and the converging portion, or proper orbital apex, anteriorly. From an endoscopic endonasal approach, the optic nerve, superior orbital fissure, and orbital apex convergence prominences were found to form a π-shaped configuration. This π-shaped configuration was indicative of the orbital apex and was an important landmark for decompression of the orbital apex. Endonasal decompression of the orbital apex in the two patients resulted in the satisfactory recovery of extraocular mobility, with no surgical complications.ConclusionsEEDCFA is feasible, effective, and safe for patients with TOAS caused by direct compression of displaced fracture segments. The π-shaped configuration is a valuable landmark for EEDCFA.

A dynamical analysis of the Taurid Complex: evidence for past orbital convergences

ABSTRACT The goal of this work is to determine if the dynamics of individual Taurid Complex (TC) objects are consistent with the formation of the complex via fragmentation of a larger body, or if the current orbital affinities between the TC members result from other dynamical processes. To this end, the orbital similarity through the time of comet 2P/Encke, 51 near-Earth asteroids (NEAs), and 16 Taurid fireballs was explored. Clones of each body were numerically simulated backwards in time, and epochs when significant fractions of the clones of any two bodies approached each other with both a low Minimum Orbit Intersection Distance and small relative velocity were identified. Only 12 pairs of bodies in our sample show such an association in the past 20 000 yr, primarily circa 3200 BCE. These include 2P/Encke and NEAs 2004 TG10, 2005 TF50, 2005 UR, 2015 TX24, and several Southern Taurid fireballs. We find this orbital convergence to be compatible with the fragmentation of a large parent body 5000–6000 yr ago, resulting in the separation of 2P/Encke and several NEAs associated with the TC, as well as some larger meteoroids now recorded in the Taurid stream. However, the influence of purely dynamical processes may offer an alternative explanation for this orbital rapprochement without requiring a common origin between these objects. In order to discriminate between these two hypotheses, future spectral surveys of the TC asteroids are required.

Separation of electron-electron and electron-proton correlation in multicomponent orbital-optimized perturbation theory.

The multicomponent orbital-optimized second-order Møller-Plesset perturbation theory (OOMP2) method is the first multicomponent MP2 method that is able to calculate qualitatively accurate protonic densities, protonic affinities, and geometrical changes due to nuclear quantum effects in multicomponent systems. In this study, two approximations of the multicomponent OOMP2 method are introduced in an effort to demonstrate that, in orbital-optimized multicomponent methods, performing the orbital-optimization process with only electron-proton correlation is sufficient to obtain accurate protonic properties. Additionally, these approximations should reduce the computational expense of the multicomponent OOMP2 method. In the first approximation, the first-order wave function is written as a linear combination of one-electron one-proton excitations rather than as a linear combination of one-electron one-proton and two-electron excitations as in the original multicomponent OOMP2 method. Electron-electron correlation is included perturbatively after the orbital-optimization procedure has converged. In the second approach, the first approximation is further modified to neglect all terms in the orbital-rotation gradients that depend on the two-electron molecular-orbital integrals, which, assuming a fixed-sized protonic basis set, reduces the computational scaling for the orbital-optimization iterations to Ne 3, where Ne is a measure of the electronic system size, compared to the Ne 5 scaling of the original multicomponent OOMP2 method. The second approximation requires one Ne 5 step after orbital convergence to compute the electron-electron correlation energy. The accuracy of the calculated protonic densities, protonic affinities, and optimized geometries of these approximations is similar or improved relative to the original multicomponent OOMP2 method.

Мэтр качественной теории и теории устойчивости динамических систем (к 100­-летию со дня рождения Александра Андреевича Шестакова)

The article presents the biography of Alexander A. Shestakov — ScD in Physics and Mathematics, Professor, a major scientist who had a wide range of scientific interests. His researches are devoted to the key problems of quality theory of differential equations, stability theory of dynamic systems, and also various applied aspects of these theories to problems of dynamics of transport systems. Professor Shestakov and his students and followers have obtained significant results in various fields of fundamental and applied mathematics, as well as mechanics. The article provides a brief overview of the scientific and pedagogical heritage of the scientist who is an organizer and founder of the famous scientific school on quality theory of dynamic processes and stability theory of differential equation solutions. He and his numerous students obtained fundamental results related to the development of the theory of stability in the sense of A.M. Lyapunov and the theory of stability in the sense of N.E. Zhukovsky, with the development of methods for the analysis of orbital stability, limitation and convergence of solutions of differential equations, with the development of limit equations and method of localization of limit sets, with theoretical and applied problems of stability of mathematical models of dynamics of railway transport. Its manuals, textbooks and monographs are the standard of fundamentality of the issues presented in them and have not lost their relevance to our days.

Anatomical Specializations Related to Foraging in the Visual System of a Nocturnal Insectivorous Bird, the Band-Winged Nightjar (Aves: Caprimulgiformes)

Nocturnal animals that rely on their visual system for foraging, mating, and navigation usually exhibit specific traits associated with living in scotopic conditions. Most nocturnal birds have several visual specializations, such as enlarged eyes and an increased orbital convergence. However, the actual role of binocular vision in nocturnal foraging is still debated. Nightjars (Aves: Caprimulgidae) are predators that actively pursue and capture flying insects in crepuscular and nocturnal environments, mainly using a conspicuous “sit-and-wait” tactic on which pursuit begins with an insect flying over the bird that sits on the ground. In this study, we describe the visual system of the band-winged nightjar (Systellura longirostris), with emphasis on anatomical features previously described as relevant for nocturnal birds. Orbit convergence, determined by 3D scanning of the skull, was 73.28°. The visual field, determined by ophthalmoscopic reflex, exhibits an area of maximum binocular overlap of 42°, and it is dorsally oriented. The eyes showed a nocturnal-like normalized corneal aperture/axial length index. Retinal ganglion cells (RGCs) were relatively scant, and distributed in an unusual oblique-band pattern, with higher concentrations in the ventrotemporal quadrant. Together, these results indicate that the band-winged nightjar exhibits a retinal specialization associated with the binocular area of their dorsal visual field, a relevant area for pursuit triggering and prey attacks. The RGC distribution observed is unusual among birds, but similar to that of some visually dependent insectivorous bats, suggesting that those features might be convergent in relation to feeding strategies.

Compound Angular Lens for Radio Orbital Angular Momentum Coaxial Separation and Convergence

Effective separation of different modes is very important for orbital angular momentum (OAM) multiplexing systems. In this letter, a coaxial separation and convergence scheme for multiple OAM modes is proposed based on a compound angular lens (CAL) module. Whether at the transmitter or the receiver, this CAL module can implement modes division and beams convergence of multiple OAM signals simultaneously along the transmission axis. This scheme does not require the RF links compensation and complex demultiplexing algorithms, which greatly simplifies the structure of the receiver. The experimental results show that the crosstalk between multiple OAM channels can be effectively reduced. This work will have an important implication in the coaxial OAM transmission application such as the fronthaul and the backhaul.

Ontogeny of Orbit Orientation in Primates.

Orbit orientation in primates has been linked to adaptive factors related to activity pattern and size-related variation in structural influences on orbit position. Although differences in circumorbital form between anthropoids and strepsirrhines appear to be related to interspecific disparities in levels of orbital convergence and orbital frontation, there is considerable overlap in convergence between suborders. Unfortunately, putative links between convergence and frontation across primates, and consequent arguments about primate and anthropoid origins, are likely to be influenced by allometry, the size range of a respective sample, and adaptive influences on encephalization and activity patterns. Such a multifarious system is less amenable to interspecific treatment across higher-level clades. An ontogenetic perspective is one way to evaluate transformations from one character state to another, especially as they pertain to allometric effects on phenotypic variation. We characterized the ontogeny of orbital convergence and frontation in 13 anthropoid and strepsirrhine species. In each suborder, correlation and regression analyses were used to test hypotheses regarding the allometric bases of variation in orbital orientation. Growth trajectories were analyzed intra- and inter-specifically. Frontation decreased postnatally in all taxa due to the negative scaling of brain vs. skull size. Further, interspecific variation in relative levels of frontation was linked to corresponding ontogenetic transpositions in encephalization that differed within both suborders. In strepsirrhines, postnatal increases in convergence were largely due to the negative allometry of orbit vs. skull size. In contrast, convergence in anthropoids varied little during growth, being unrelated to ontogenetic variation in either relative orbit or interorbit size. Anat Rec, 302:2093-2104, 2019. © 2019 American Association for Anatomy.

Rethinking the Origin of Primates by Reconstructing Their Diel Activity Patterns Using Genetics and Morphology

Phylogenetic inference typically invokes nocturnality as ancestral in primates; however, some recent studies posit that diurnality is. Here, through adaptive evolutionary analyses of phototransduction genes by using a variety of approaches (restricted branch/branch-site models and unrestricted branch-site-based models (BS-REL, BUSTED and RELAX)), our results consistently showed that ancestral primates were subjected to enhanced positive selection for bright-light vision and relatively weak selection for dim-light vision. These results suggest that ancestral primates were mainly diurnal with some crepuscularity and support diurnality as plesiomorphic from Euarchontoglires. Our analyses show relaxed selection on motion detection in ancestral primates, suggesting that ancestral primates decreased their emphasis on mobile prey (e.g., insects). However, within primates, the results show that ancestral Haplorrhini were likely nocturnal, suggesting that evolution of the retinal fovea occurred within ancestral primates rather than within haplorrhines as was previously hypothesized. Our findings offer a reassessment of the visual adaptation of ancestral primates. The evolution of the retinal fovea, trichromatic vision and orbital convergence in ancestral primates may have helped them to efficiently discriminate, target, and obtain edible fruits and/or leaves from a green foliage background instead of relying on mobile insect prey.

Steering Orbital Optimization out of Local Minima and Saddle Points Toward Lower Energy.

The general procedure underlying Hartree-Fock and Kohn-Sham density functional theory calculations consists in optimizing orbitals for a self-consistent solution of the Roothaan-Hall equations in an iterative process. It is often ignored that multiple self-consistent solutions can exist, several of which may correspond to minima of the energy functional. In addition to the difficulty sometimes encountered to converge the calculation to a self-consistent solution, one must ensure that the correct self-consistent solution was found, typically the one with the lowest electronic energy. Convergence to an unwanted solution is in general not trivial to detect and will deliver incorrect energy and molecular properties and accordingly a misleading description of chemical reactivity. Wrong conclusions based on incorrect self-consistent field convergence are particularly cumbersome in automated calculations met in high-throughput virtual screening, structure optimizations, ab initio molecular dynamics, and in real-time explorations of chemical reactivity, where the vast amount of data can hardly be manually inspected. Here, we introduce a fast and automated approach to detect and cure incorrect orbital convergence, which is especially suited for electronic structure calculations on sequences of molecular structures. Our approach consists of a randomized perturbation of the converged electron density (matrix) intended to push orbital convergence to solutions that correspond to another stationary point (of potentially lower electronic energy) in the variational parameter space of an electronic wave function approximation.

On Orbital Stabilization for Industrial Manipulators: Case Study in Evaluating Performances of Modified PD+ and Inverse Dynamics Controllers

Orbital stabilization is one of the available alternatives to the classical asymptotic stabilization, known as the reference tracking control, which is typically considered and implemented for controlling motions of industrial robot manipulators. Since asymptotic orbital stability means convergence of solutions of a closed-loop system to an orbit of a reference trajectory, instead of tracking it as a function of time, new feedback designs can potentially improve performance with respect to several key criteria for industrial manipulators such as absolute path accuracy for tool’s motions and robustness to uncertainties in the model. The main outcomes of this paper are a new class of controllers that achieve asymptotic orbital stabilization of motions and a novel analytical method for analysis and redesign of system’s dynamics using an excessive set of easy-to-compute transverse coordinates. The contributions have been validated in a series of experimental studies performed on a standard industrial robot ABB IRB 140 with the IRC5-system extended with an open control interface. The outcomes of the tests show that the proposed redesign allows achieving significantly reduced deviations of the actual trajectories from the desired ones at different ranges of speeds and for several different paths, often outperforming the state-of-the-art commercial implementations. A comprehensive discussion of one of such experiments is given.

Toward Understanding the Mammalian Zygoma: Insights From Comparative Anatomy, Growth and Development, and Morphometric Analysis.

The zygoma, or jugum, is a cranial element that was present in Mesozoic tetrapods, well before the appearance of mammals. Although as an entity the zygoma is a primitive retention among mammals, it has assumed myriad configurations as this group diversified. As the zygoma is located at the intersection of the visual, respiratory, and masticatory apparatuses, it is potentially of great importance in systematic, phylogenetic, and functional studies focused on this region. For example, the facial component of the zygoma and its contribution to a postorbital bar (POB) appear to be relevant to the systematics of a number of mammalian subclades, and the formation of a bony postorbital septum (POS) that separates the orbit from the infratemporal fossa is unique to, and thus potentially phylogenetically significant for uniting anthropoid primates, while the zygoma itself appears to serve to resist tension and bending forces during mastication. In order to better understand the zygoma in the context of its contributions to the circumorbital region, we documented its morphological expression in specimens representing 10 orders of mammals. Since the presence of a POB and of a POS has long been used to justify uniting extant primates and anthropoid primates as respective clades, and because postorbital closure (POC) is morphologically more complex than a POB, we provide detail necessary to address these claims. Our taxically broad overview also allowed us to provide for the first time definitions of configurations that can be applied to future studies. Using a different, but also taxically broad sample of mammals, and of primates in particular, we performed two geometric morphometric analyses that were geared toward testing long-held interpretations of the functional role of the zygoma, especially with regard to mastication and in the context of orbital frontation (to which the zygoma contributes). Further, overall, zygomatic morphology tends not to scale with allometry, sexual dimorphism, or angle of orbital convergence, but it does contribute to unique patterns of intraspecies variation. Anat Rec, 300:76-151, 2017. © 2016 Wiley Periodicals, Inc.

Phylogenetic signals in the primate sphenoid bone at birth

The sphenoid is often considered to be the keystone of the skull. Many cranial traits are used to distinguish phylogenetic groups among primates, and the sphenoid is an influential element in these differences. Because of the importance of the sphenoid for the integration of face, vault, and cranial base, we expected that many of these traits would be apparent early in cranial osteogenesis, establishing the framework for future development. We tested three specific hypotheses in neonate specimens of haplorhine and strepsirrhine primates. First, based on greater encephalization of haplorhine adult primates relative to strepsirrhine primates (and despite reports that haplorhines show pronounced brain growth postnatally), we predicted that the cranial base would show greater flexion in haplorhines. Second, based on expanded temporal lobes in haplorhines relative to strepsirrhines, we expected that the alisphenoid would be expanded in haplorhines. Third, based on orbital convergence of haplorhine adult primates, we predicted that the width of the presphenoid would be greater in strepsirrhine neonate primates relative to haplorhines.We evaluated perinatal (late fetal through six days postnatal) specimens of primates representing strepsirrhine and haplorhine taxa. MicroCT imaging data were used to create 3D reconstructions of each cranium. Cranial base angle was estimated by the angle between the sphenoidal and clival planes. The alisphenoid was evaluated qualitatively as the rostral portion of that bone separating orbit and middle cranial fossa. Finally, width of the presphenoid was evaluated as the width between the optic canals, inferior to the orbitosphenoid (lesser wings).Our results indicate that the sphenoid is highly variable in structure among the primate taxa under study. In all cases, the intrasphenoidal synchondrosis between the presphenoid and the basisphenoid remained patent. In many cases, the alisphenoid elements remained separate. We observed notable variation in the presphenoid, including length and width of the lesser wings. Despite the apparent variation, we did not find consistent evidence in support of our expectations based on phylogenetic signal. Cranial base angle did not differ between haplorhines and strepsirrhines, indicating that the influence of encephalization affects the cranial base postnatally. This is consistent with reports of increased brain growth in haplorhines in the postnatal period. We observed an expanded alisphenoid in haplorhines relative to some, but not all, of the strepsirrhines. Notably, the strepsirrhine Otolemur showed alisphenoid expansion rostral to the poles of the temporal lobes. Finally, we found a relatively wide presphenoid in many, but not all, of the strepsirrhines. The lesser wings of the presphenoid accommodated an enlarged olfactory fossa in all strepsirrhines, but the relative width of the presphenoid of Otolemur was within the range observed in haplorhines. Our results indicate that some of the sphenoidal traits that carry a phylogenetic signal in adults are present in many, but not all, neonate primates. These include width of the presphenoid and extent of the alisphenoid. In contrast, the effect of encephalization on cranial base angle occurs postnatally. In addition, it is apparent that factors independent of phylogeny influence the structure of the sphenoid in neonate primates.Support or Funding InformationNSF BCS‐1231717, NSF BCS‐1231350, NSF BCS‐0959438

A Flat-Lensed Spiral Phase Plate Based on Phase-Shifting Surface for Generation of Millimeter-Wave OAM Beam

A multilayer phase-shifting-surface-based flat plate is designed to offer a combination of lens and spiral phase plate (SPP) for orbital angular momentum (OAM) beam generation and convergence at 60 GHz. The proposed design consists of a series of phase-shift unit cells to control the emergent phase and form a flat lens for the purpose of beam focusing. The results of simulation and experiment verify that the OAM beam with small divergence angle can be achieved.

Unique human orbital morphology compared with that of apes.

Humans’ and apes’ convergent (front-facing) orbits allow a large overlap of monocular visual fields but are considered to limit the lateral visual field extent. However, humans can greatly expand their lateral visual fields using eye motion. This study aimed to assess whether the human orbital morphology was unique compared with that of apes in avoiding lateral visual field obstruction. The orbits of 100 human skulls and 120 ape skulls (30 gibbons; 30 orangutans; 30 gorillas; 30 chimpanzees and bonobos) were analyzed. The orbital width/height ratio was calculated. Two orbital angles representing orbital convergence and rearward position of the orbital margin respectively were recorded using a protractor and laser levels. Humans have the largest orbital width/height ratio (1.19; p < 0.001). Humans and gibbons have orbits which are significantly less convergent than those of chimpanzees / bonobos, gorillas and orangutans (p < 0.001). These elements suggest a morphology favoring lateral vision in humans. More specifically, the human orbit has a uniquely rearward temporal orbital margin (107.1°; p < 0.001), suitable for avoiding visual obstruction and promoting lateral visual field expansion through eye motion. Such an orbital morphology may have evolved mainly as an adaptation to open-country habitat and bipedal locomotion.