Face Configuration Research Articles

The effective equivalence of geometric irregularity and surface roughness in determining particle single-scattering properties.

This study investigates the effects of geometric irregularity and surface roughness on the single-scattering properties of randomly oriented dielectric particles. Starting from a regular crystal with smooth faces, effects of roughening are compared with effects of perturbing the regular configuration of the smooth faces. Using the same slope distribution for small roughness facets and tilted faces provides a natural way to compare the effects on the single-scattering properties. It is found that the geometric irregularity and surface roughness have similar effects on the single-scattering properties of an ensemble of randomly oriented particles. In other words, particles with irregular geometries and those with surface roughness are optically equivalent if the slope distributions are the same. Furthermore, an ensemble of particles with irregular geometries can be used as an effective approximation for simulation of the scattering properties of roughened particles, and vice versa. This approach also provides new interpretation of the observed, relatively featureless and smooth, scattering phase functions of naturally occurring particles.

Bodies are Represented as Wholes Rather Than Their Sum of Parts in the Occipital-Temporal Cortex

Behavioral studies suggested that bodies are represented as wholes rather than in a part-based manner. However, neural selectivity for body stimuli is found for both whole bodies and body parts. It is therefore undetermined whether the neural representation of bodies is configural or part-based. We used functional MRI to test the role of first-order configuration on body representation in the human occipital-temporal cortex by comparing the response to a whole body versus the sum of its parts. Results show that body-selective areas, whether defined by selectivity to headless bodies or body parts, preferred whole bodies over their sum of parts and successfully decoded body configuration. This configural representation was specific to body stimuli and not found for faces. In contrast, general object areas showed no preference for wholes over parts and decoded the configuration of both bodies and faces. Finally, whereas effects of inversion on configural face representation were specific to face-selective mechanisms, effects of body inversion were not unique to body-selective mechanisms. We conclude that the neural representation of body parts is strengthened by their arrangement into an intact body, thereby demonstrating a central role of first-order configuration in the neural representation of bodies in their category-selective areas.

Design Techniques for the DNA Cubic-Lattice

We use the Watson-Crick properties of DNA and the principles of graph theory to construct origami folding designs for self-assembling cubic lattices. Our objective is a mathematical design strategy that can be expanded systematically to any size cubic lattice. This design consists of threading a scaffolding strand of DNA through the lattice that is secured in place by short staple strands of DNA. We first add augmenting edges to the cubic lattice to enable a single scaffolding strand threading. We then thread the scaffolding strand through the augmented cube in a way that minimizes the number of different vertex configurations in the structure. Key Words: Watson-Crick, DNA Self-Assembly, Origami folding, Cubic Lattice, Scaffolding Strand, Threading, Staple Strands

FMRI decoding reveals impaired face configuration representation in the right fusiform face area of individuals with developmental prosopagnosia

fMRI decoding reveals impaired face configuration representation in the right fusiform face area of individuals with developmental prosopagnosia

Coordinate-space singularities of massless gauge theories

The structure of singularities in perturbative massless gauge theories is investigated in coordinate space. The pinch singularities in coordinate-space integrals occur at configurations of vertices which have a direct interpretation in terms of physical scattering of particles in real space-time in the same way as for the loop momenta in the case of momentum-space singularities. In the analysis of vertex functions in coordinate space, the well-known factorization into hard, soft, and jet functions is found. By power-counting arguments, it is found that coordinate-space integrals of vertex functions have logarithmic divergences at worst.

On the algorithmic complexity of crystals

AbstractThe concept of the algorithmic complexity of crystals is developed for a particular class of minerals and inorganic materials based on orthogonal networks, which are defined as networks derived from the primitive cubic net (pcu) by the removal of some vertices and/or edges. Orthogonal networks are an important class of networks that dominate topologies of inorganic oxysalts, framework silicates and aluminosilicate minerals, zeolites and coordination polymers. The growth of periodic orthogonal networks may be modelled using structural automata, which are finite automata with states corresponding to vertex configurations and transition symbols corresponding to the edges linking the respective vertices. The model proposed describes possible relations between theoretical crystallography and theoretical computer science through the theory of networks and the theory of deterministic finite automata.

Local feature suppression effect in face and non-face stimuli

There is evidence that the cognitive system processes human faces faster and more precisely than other stimuli. Also, faces summon visual attention in an automatic manner, as evidenced by efficient, 'pop-out' search for face targets amongst homogeneous non-face distractors. Pop-out for faces implies that faces are processed as a basic visual 'feature' by specialized face-tuned detectors, similar to the coding of other features (e.g., color, orientation, motion, etc.). However, it is unclear whether such face detectors encode only the global face configuration or both global and local face features. If the former were correct, the face detectors should be unable to support search for a local face feature, rendering search slower relative to non-face stimuli; that is, there would be local feature suppression (LFS) for faces. If the latter was the case, there should be no difference in the processing of local and, respectively, global face features. In two experiments, participants discerned the presence (vs. absence) of a local target defined as a part of either a normal or a scrambled (schematic or realistic) face or of a non-face (Kanizsa diamond or realistic house) configuration. The results consistently showed a robust LFS effect in both reaction times and error rates for face stimuli, and either no difference or even a local feature enhancement effect for the control stimuli. Taken together, these findings indicate that faces are encoded as a basic visual feature by means of globally tuned face detectors.

Damping evaluation on eco-friendly sandwich panels through reverberation time (RT60) measurements

Problems involving vibrations occur in many fields of engineering. Thus, it is necessary to increase the knowledge of the damping, offered by new structural configurations and materials in order to reduce the vibration levels. The present paper focuses its attention on the measurements of the structural loss factor of different types of sandwich panels made of eco-friendly materials. The interest in natural materials, for structural applications, has considerably increased in the last years thanks to the growing environmental concerns. The influence on the loss factor of face sheet materials, core types and configurations is experimentally evaluated by means of measurements of the reverberation time (RT60). The reported data represent a good initial database for more detailed analyses of these new materials.

The composite effect for inverted faces is reliable at large sample sizes and requires the basic face configuration

The absence of the face composite effect (FCE) for inverted faces is often considered evidence that holistic processing operates only on upright faces. However, such absence might be explained by power issues: Most studies that have failed to find the inverted FCE tested 24 participants or less. Here we find that the inverted FCE exists reliably when we tested at least 60 participants. The inverted FCE was ∼ 18% the size of the upright FCE, and it was unaffected by testing order: It did not matter whether participants did the upright condition first (Experiment 1, n = 64) or the inverted condition first (Experiment 2, n = 68). The effect also remained when upright and inverted trials were mixed (Experiment 3, n = 60). An individual differences analysis found a modest positive correlation between inverted and upright FCE, suggesting partially shared mechanisms. A critical control experiment demonstrates that the inverted FCE cannot be explained by visuospatial attention or other generic accounts because the effect disappeared when the basic face configuration was disrupted (Experiment 4, n = 50). Our study shows that the inverted FCE is a reliable effect that requires an intact face configuration, consistent with the notion that some holistic processing also operates on inverted faces.

Effects of Bearing Configuration on Spindle Dynamic Characteristics

This article investigates the effects of bearing configuration on the spindle dynamic characteristics. First, an analytical model of spindle is proposed and the bearing sets radial stiffness is calculated. Second, the spindle analytical model is developed to perform modal analysis and harmonic response analysis with ANSYS, and then obtain the natural frequency and FRF under different bearing configurations. The result suggests that bearing configuration has little effect on the natural frequency of spindle system and the FRF amplitude corresponding to the 1st natural frequency under back to back configuration or face to face configuration is relatively small. Finally, the proposed model is validated by modal experiment.

An objective signature for visual binding of face parts in the human brain

Whether and how the parts of a visual object are grouped together to form an integrated ("holistic") representation is a central question in cognitive neuroscience. Although the face is considered to be the quintessential example of holistic representation, this issue has been the subject of much debate in face perception research. The implication of holistic processing is that the response to the whole cannot be predicted from the sum of responses to the parts. Here we apply techniques from nonlinear systems analysis to provide an objective measure of the nonlinear integration of parts into a whole, using the left and right halves of a face stimulus as the parts. High-density electroencephalogram (EEG) was recorded in 15 human participants presented with two halves of a face stimulus, flickering at different frequencies (5.88 vs. 7.14 Hz). Besides specific responses at these fundamental frequencies, reflecting part-based responses, we found intermodulation components (e.g., 7.14 - 5.88 = 1.26 Hz) over the right occipito-temporal hemisphere, reflecting nonlinear integration of the face halves. Part-based responses did not depend on the relative alignment of the two face halves, their spatial separation, or whether the face was presented upright or inverted. By contrast, intermodulations were virtually absent when the two halves were spatially misaligned and separated. Inversion of the whole face configuration also reduced specifically the intermodulation components over the right occipito-temporal cortex. These observations indicate that the intermodulation components constitute an objective, configuration-specific signature of an emergent neural representation of the whole face that is distinct from that generated by the parts themselves.

Schiff Base Switch II Precedes the Retinal Thermal Isomerization in the Photocycle of Bacteriorhodopsin

In bacteriorhodopsin, the order of molecular events that control the cytoplasmic or extracellular accessibility of the Schiff bases (SB) are not well understood. We use molecular dynamics simulations to study a process involved in the second accessibility switch of SB that occurs after its reprotonation in the N intermediate of the photocycle. We find that once protonated, the SB C15 = NZ bond switches from a cytoplasmic facing (13-cis, 15-anti) configuration to an extracellular facing (13-cis, 15-syn) configuration on the pico to nanosecond timescale. Significantly, rotation about the retinal’s C13 = C14 double bond is not observed. The dynamics of the isomeric state transitions of the protonated SB are strongly influenced by the surrounding charges and dielectric effects of other buried ions, particularly D96 and D212. Our simulations indicate that the thermal isomerization of retinal from 13-cis back to all-trans likely occurs independently from and after the SB C15 = NZ rotation in the N-to-O transition.

Recognition of Face and Non‐Face Stimuli in Autistic Spectrum Disorder

The ability to remember faces is critical for the development of social competence. From childhood to adulthood, we acquire a high level of expertise in the recognition of facial images, and neural processes become dedicated to sustaining competence. Many people with autism spectrum disorder (ASD) have poor face recognition memory; changes in hairstyle or other non-facial features in an otherwise familiar person affect their recollection skills. The observation implies that they may not use the configuration of the inner face to achieve memory competence, but bolster performance in other ways. We aimed to test this hypothesis by comparing the performance of a group of high-functioning unmedicated adolescents with ASD and a matched control group on a "surprise" face recognition memory task. We compared their memory for unfamiliar faces with their memory for images of houses. To evaluate the role that is played by peripheral cues in assisting recognition memory, we cropped both sets of pictures, retaining only the most salient central features. ASD adolescents had poorer recognition memory for faces than typical controls, but their recognition memory for houses was unimpaired. Cropping images of faces did not disproportionately influence their recall accuracy, relative to controls. House recognition skills (cropped and uncropped) were similar in both groups. In the ASD group only, performance on both sets of task was closely correlated, implying that memory for faces and other complex pictorial stimuli is achieved by domain-general (non-dedicated) cognitive mechanisms. Adolescents with ASD apparently do not use domain-specialized processing of inner facial cues to support face recognition memory.

Early holistic face-like processing of Arcimboldo paintings in the right occipito-temporal cortex: Evidence from the N170 ERP component

The properties of the face-sensitive N170 component of the event-related brain potential (ERP) were explored through an orientation discrimination task using natural faces, objects, and Arcimboldo paintings presented upright or inverted. Because Arcimboldo paintings are composed of non-face objects but have a global face configuration, they provide great control to disentangle high-level face-like or object-like visual processes at the level of the N170, and may help to examine the implication of each hemisphere in the global/holistic processing of face formats. For upright position, N170 amplitudes in the right occipito-temporal region did not differ between natural faces and Arcimboldo paintings but were larger for both of these categories than for objects, supporting the view that as early as the N170 time-window, the right hemisphere is involved in holistic perceptual processing of face-like configurations irrespective of their features. Conversely, in the left hemisphere, N170 amplitudes differed between Arcimboldo portraits and natural faces, suggesting that this hemisphere processes local facial features. For upside-down orientation in both hemispheres, N170 amplitudes did not differ between Arcimboldo paintings and objects, but were reduced for both categories compared to natural faces, indicating that the disruption of holistic processing with inversion leads to an object-like processing of Arcimboldo paintings due to the lack of local facial features. Overall, these results provide evidence that global/holistic perceptual processing of faces and face-like formats involves the right hemisphere as early as the N170 time-window, and that the local processing of face features is rather implemented in the left hemisphere.

Combined effects of inversion and feature removal on N170 responses elicited by faces and car fronts

The face-sensitive N170 is typically enhanced for inverted compared to upright faces. Itier, Alain, Sedore, and McIntosh (2007) recently suggested that this N170 inversion effect is mainly driven by the eye region which becomes salient when the face configuration is disrupted. Here we tested whether similar effects could be observed with non-face objects that are structurally similar to faces in terms of possessing a homogeneous within-class first-order feature configuration. We presented upright and inverted pictures of intact car fronts, car fronts without lights, and isolated lights, in addition to analogous face conditions. Upright cars elicited substantial N170 responses of similar amplitude to those evoked by upright faces. In strong contrast to face conditions however, the car-elicited N170 was mainly driven by the global shape rather than the presence or absence of lights, and was dramatically reduced for isolated lights. Overall, our data confirm a differential influence of the eye region in upright and inverted faces. Results for car fronts do not suggest similar interactive encoding of eye-like features and configuration for non-face objects, even when these objects possess a similar feature configuration as faces.

A Single Cluster Covering for Dodecagonal Quasiperiodic Ship Tiling

The single cluster covering approach provides a plausible mechanism for the formation and stability of octagonal and decagonal quasiperiodic structures. For dodecagonal quasiperiodic patterns, such a single cluster covering scheme is still unavailable. We demonstrate that ship tiling, one of the dodecagonal quasiperiodic structures, can be completely covered by a single cluster. A deflation procedure is devised by assigning proper orientations to different tiles, and nine types of vertex configurations, if the mirror patterns are considered to be identical, have been identified, which fulfill the closure condition under deflation and all result in a T-cluster centered at the vertex.

Using pulsed and modulated photothermal radiometry to measure the thermal conductivity of thin films

Two techniques of photothermal radiometry (PTR) in front face configuration were used to determine the thermal conductivity of thin nanocrystalline films. The first technique relies on using modulated laser beam as a heating source. The second is based on pulsed laser heating where the pulse can be assimilated to a Dirac function. In the two measurement setups, the infrared radiation emitted from the heated surface of the sample is measured by an infrared detector. The thermal conductivity of CrN thin films prepared with various thicknesses by magnetron sputtering on silicon substrates was investigated by both techniques showing a dependence on the film microstructure. The thermal resistance at the film-substrate interface and intrinsic thermal conductivity of the films were identified by the two techniques and are in a very good agreement. In addition to the interface thermal resistance, the measurements revealed lower thermal conductivity of very thin films that can be attributed to presence of high amount of grain boundaries and other structural defects.

Real and effective thermal equilibrium in artificial square spin ices

We have studied the magnetic microstates arising from single-shot thermalization processes that occur during growth in artificial square spin ices. The populations of different vertex types can be controlled by the system's lattice constant, as well as by the deposition of different material underlayers. The statistics of these populations are well described by a simple model based on the canonical ensemble, which is used to infer an effective temperature for an arrested microstate. The normalized energy level spacings of the different magnetic vertex configurations are found to be very close to those predicted for a point-dipole model: this is shown to be a very good approximation to energy level spacings calculated for finite-sized cuboid magnetic bodies. States prepared with a rotating field (an athermal method commonly used to lower the energy of these systems) cannot be described by this model, showing that such a method does not induce a near-equilibrium state.

Perceiving conspecifics as integrated body-gestalts is an embodied process.

We investigated the effect of posture congruence on social perception. Specifically, we tested the hypothesis that completing "body gestalts," rather than being a purely visual process, is mediated by congruence in the postures of observer and stimulus. We developed novel stimuli showing a face and 2 hands that could be combined in various ways to form "body gestalts" implying different postures. In 3 experiments we found that imitative finger movements were consistently faster when the observer's posture matched the posture implied by the configuration of face and hands shown onscreen, suggesting that participants intuitively used their own body schema to "fill in the gaps" in the stimuli. Besides shaping how humans perceive others' bodies, embodied body-gestalt (eBG) completion may be an essential social and survival mechanism, for example, allowing for quick recovery from deceptive actions. It may also partly explain why humans subconsciously align themselves in everyday interactions: This might facilitate optimal corepresentation at higher, conscious levels.

Holistic Face Processing is Induced by Shape and Texture

There is increasing evidence that shape and texture are integral parts of face identity. However, it is less clear whether face-specific processing mechanisms are triggered by face shape alone, or if texture might play an important role. We address this question by studying mechanisms involved in holistic face processing. Face stimuli were either full-color pictures of real faces (shape and texture) or line drawings of the same faces (shape without texture). In a change detection task subjects judged whether eyes and eyebrows in two otherwise identical, sequentially presented faces were different in size or not. Afterwards, subjects had to identify the just presented face among two distractor faces (forced-choice identification task). The results obtained from the two tasks give rise to the conclusion that face identification and change detection tasks engage different processing strategies, which capture different aspects of holistic processing. Real faces were processed holistically, irrespective of task requirements, whereas line drawings were processed holistically only if face identification was required. On the basis of the data we conclude that face shape is relevant for the initial processing stage and feature binding, whereas face texture seems to be involved in processing of face configuration more specifically. Moreover, results demonstrate considerable flexibility of the face processing systems allowing for goal-directed and task-specific recall of face information.