Error Aberrations Research Articles

Contextualizing individual differences in error monitoring: Links with impulsivity, negative affect, and conscientiousness.

The error-related negativity (ERN) is a neural measure of error processing that has been implicated as a neurobehavioral trait and has transdiagnostic links with psychopathology. Few studies, however, have contextualized this traitlike component with regard to dimensions of personality that, as intermediate constructs, may aid in contextualizing links with psychopathology. Accordingly, the aim of this study was to examine the interrelationships between error monitoring and dimensions of personality within a large adult sample (N = 208). Building on previous research, we found that the ERN relates to a combination of negative affect, impulsivity, and conscientiousness. At low levels of conscientiousness, negative urgency (i.e., impulsivity in the context of negative affect) predicted an increased ERN; at high levels of conscientiousness, the effect of negative urgency was not significant. This relationship was driven specifically by the conscientiousness facets of competence, order, and deliberation. Links between personality measures and error positivity amplitude were weaker and nonsignificant. Post-error slowing was also related to conscientiousness, as well as a different facet of impulsivity: lack of perseverance. These findings suggest that, in the general population, error processing is modulated by the joint combination of negative affect, impulsivity, and conscientiousness (i.e., the profile across traits), perhaps more so than any one dimension alone. This work may inform future research concerning aberrant error processing in clinical populations.

Electrophysiological evidence of a typical cognitive distortion in bipolar disorder

Patients suffering from bipolar disorder often report negative thoughts and a bias towards negative environmental stimuli. Previous studies show that this mood-congruent attentional bias could mediated by dysfunctions in anterior limbic regions. The Error-Related Negativity (ERN), which originates in the anterior cingulate cortex (ACC), has been used to research this negativity bias in depressed patients, and could also help to better understand the underlying mechanisms causing the negativity bias in bipolar patients.In this study we investigated error processing in patients with bipolar disorder. Acute depressive bipolar patients (n = 20) and age-matched healthy controls (n = 20) underwent a modified Eriksen Flanker Task to assess test performance and two error-related event-related potentials (ERPs), i.e., the ERN and Error Positivity (Pe) were measured by EEG. Half of the patients were measured again in a euthymic state.We found similar ERN amplitudes in bipolar patients as compared to healthy controls, but significantly reduced Pe amplitudes. Moreover, acutely depressed bipolar patients displayed an ERN and Pe even if they responded accurately or too slow, which indicates that correct responses are processed in a way similar to wrong responses. This can be interpreted as a psychophysiological correlate of typical cognitive distortions in depression, i.e., an erroneous perception of personal failures. This biased error perception partially remained when patients were in a euthymic state.Together, our data indicate that aberrant error processing of bipolar patients may be regarded a trait marker possibly reflecting a risk factor for depressive relapses in bipolar disorder.

Evaluation of outliers in acquired brain MR images

Pre-processing is an important stage in the analysis of magnetic resonance images (MRI), because the effect of specific image artefacts, such as intensity inhomogeneity, noise and low contrast can adversely affect the quantitative image analysis. The image histogram is a useful tool in the analysis of MR images given that it allows a close relationship with important image features such as contrast and noise. The noise and variable contrast are elements that locally modify the quality of images. The key issue of this study derives from the fact that the spatial histogram can contain outliers indicating corrupted image information through the disorder of the bins. These aberrant errors should be excluded from the studied data sets. Here, the outliers are evaluated by using rigorous methods based on the probability theory and Chauvenet (CC), Grubbs (GC) and Peirce's (PC) criteria. In order to check the quality of the MR images, the Minkowsky (MD), Euclidean (ED) and cosine (CD) distance functions were used. They act as similarity scores between the histogram of the acquired MRI and the processed image. This analysis is necessary because, sometimes, the distance function exceeds the co-domain because of the outliers. In this paper, 32 MRIs are tested and the outliers are removed so that the distance functions generate uncorrupted and real values.

Angular Spectrum Method for the Focused Acoustic Field of a Linear Transducer

Applications involving non-destructive testing or acoustical imaging are more and more sophisticated. In this context, a model based on the angular spectrum approach is tackled in view to calculate the focused impulse field radiated by a linear transducer through a plane fluid-solid interface.It is well known that electronic focusing, based on a cylindrical delay law, like for the classical cases (lenses, curved transducer), leads to an inaccurate focusing in the solid due to geometric aberrations errors affecting refraction. Generally, there is a significant difference between the acoustic focal distance and the geometrical focal due to refraction.In our work, an optimized delay law, based on the Fermat's principle is established, particularly at an oblique incidence where the geometrical considerations, relatively simple in normal incidence, become quickly laborious.Numerical simulations of impulse field are judiciously carried out. Subsequently, the input parameters are optimally selected in order to achieve good computation accuracy and a high focusing.The overall results, involving compression and shear waves, have highlighted the focusing improvement in the solid when compared to the currently available approaches. Indeed, the acoustic focal distance is very close to geometrical focal distance and then, allows better control of the refracted angular beam profile (refraction angle, focusing depth and focal size).

Research on mechanism and application of effect of adjustment errors in aspheric surface stitching interferometry

Due to the existence of imprecise fitting of subapertures’ overlap zone, the accumulation of adjustment errors is significant during the measurement of aspheric surface by stitching interferometry. Theoretical analysis indicates that the effect and the appearance of three-direction adjustment errors accords with that of Seidel aberration, of which the axial error leads defocus, third-order spherical aberration and higher-order errors of wave front distribution. Based on the analysis we have made, a correction model has been established, and the estimated values of adjustment errors have been acquired. By correcting the higher-order aberration in the model, fitting precision of subapertures’ overlap zone can be improved. Experiment for comparison shows that, after fitting, the value of both residual error and uncertainty of measurement become smaller than those values obtained by traditional correction method of three-direction adjustment error, which proves that the stitching precision of proposed method is higher.

Assessment of Using Secondary Concentrators for Nonferrous Material Removal Applications

The paper investigates using a secondary solar concentrator to augment the solar energy density focused by a primary concentrator (a paraboloid dish). The secondary concentrator protects the focal point from cooling by convection from wind, and also would harness all the solar rays reflected by the primary concentrator, resulting in reduced losses due to aberration and other errors in finding the focal point. The intended application is the utilization of solar energy for nonferrous material ablation that could potentially replace or assist industrial lasers

Aberrant error processing in relation to symptom severity in obsessive-compulsive disorder: A multimodal neuroimaging study.

BackgroundObsessive–compulsive disorder (OCD) is characterized by maladaptive repetitive behaviors that persist despite feedback. Using multimodal neuroimaging, we tested the hypothesis that this behavioral rigidity reflects impaired use of behavioral outcomes (here, errors) to adaptively adjust responses. We measured both neural responses to errors and adjustments in the subsequent trial to determine whether abnormalities correlate with symptom severity. Since error processing depends on communication between the anterior and the posterior cingulate cortex, we also examined the integrity of the cingulum bundle with diffusion tensor imaging.MethodsParticipants performed the same antisaccade task during functional MRI and electroencephalography sessions. We measured error-related activation of the anterior cingulate cortex (ACC) and the error-related negativity (ERN). We also examined post-error adjustments, indexed by changes in activation of the default network in trials surrounding errors.ResultsOCD patients showed intact error-related ACC activation and ERN, but abnormal adjustments in the post- vs. pre-error trial. Relative to controls, who responded to errors by deactivating the default network, OCD patients showed increased default network activation including in the rostral ACC (rACC). Greater rACC activation in the post-error trial correlated with more severe compulsions. Patients also showed increased fractional anisotropy (FA) in the white matter underlying rACC.ConclusionsImpaired use of behavioral outcomes to adaptively adjust neural responses may contribute to symptoms in OCD. The rACC locus of abnormal adjustment and relations with symptoms suggests difficulty suppressing emotional responses to aversive, unexpected events (e.g., errors). Increased structural connectivity of this paralimbic default network region may contribute to this impairment.

Fabrication of a Hybrid Aspheric Lens Using Glass and Thermosetting Polymer Molding Technique

This study developed a precise hybrid optical lens (PHOL) that included polymer and glass materials. Although glass offers superior anti-thermal, anti-environmental, anti-scraped corrosion resistance and optical properties than polymer materials, it is difficult to fabricate glass materials. Therefore, it is difficult to obtain a high-accuracy aspheric glass lens. This paper presents the fabrication of a PHOL that combined aspheric polymer and glass bases using a glass-molding technique. The PHOL can be used to reduce aberration errors in optical systems using two materials. The PHOL maintains the advantages of glass materials, and the cost of aspheric polymer is lower than that of the aspheric glass layer. Thermosetting polymer was used as the aspheric part in this study. Compared to UV-curable polymer, thermosetting polymer has higher thermal stability, and the molds are not limited by glass materials, which must be transmissible by UV light. First, a glass sphere lens was used as a base of the PHOL. Subsequently, the ultra-precise diamond turning technique was used to fabricate the mold with an aspheric profile. During the molding process, the thermosetting polymer was formed into an aspheric layer and covered on the glass base. The PHOL of 11.2 mm in diameter was obtained using controlled cooling. Finally, the surface accuracy (PV) of the PHOL was less than 0.5μm, has been successfully fabricated in this study.

Reply: The Bayesian equation and psychosis

Sir, In a recent study (Chambon et al ., 2011), we investigated the ability of patients with schizophrenia to make accurate predictions about other people’s intentions. This ability has long been shown to be impaired in schizophrenia, and this impairment may be accounted for by an abnormal integration of two different sources of information: the sensory evidence conveyed by movement kinematics, and the observer’s expectations about how likely an intention is. In the task, these two types of information were systematically varied. Our results showed that patients with positive symptoms were prone to over-weight sensory evidence confirming their prior expectations and to disregard evidence that invalidated such priors. We hypothesized that this abnormal interplay of prior expectations and current sensory experiences—that normally guarantee accurate inferences—could result from a disturbance in prediction error signalling, possibly caused by alterations in the dopaminergic circuitry. We speculated that such aberrant prediction error signals might account for the formation, as well as for the update, of delusional beliefs as to how biological agents are most likely to behave. In their comment, Garrett and Singh suggest …

Roughness measurement of metals using a modified binary speckle image and adaptive optics

This paper proposes an integrated roughness measurement system that is based on adaptive optics (AO) and binary analysis of speckle pattern images. The aim of this study was to demonstrate the necessity for AO compensation in regions containing both heat and fluid flow turbulences. A speckle image was obtained by projecting a laser beam onto the specimen surface, and the laser pattern image reflected from the surface was binarized to experimentally correlate the intensity with the surface roughness. In the absence of the AO correction scheme, induced turbulences can severely increase the residual rms error from 0.14 to 1.4 μm. After a real-time closed-loop AO correction, we can reduce the wavefront root mean square (rms) error to 0.12 μm, which not only compensates for the aberration error from induced disturbances but also improves the overall performance of the optical system. In addition, an AO system having different gains was investigated, and a threshold gain value was found to be able to steadily compensate for the wavefront errors in less than 2 s. Measurement results of five steel samples having roughness ranging from 0.2 to 3.125 μm (0.3 λ and 5 λ, where λ is the diode laser wavelength) demonstrate an excellent correlation between the intensity distribution of binary images and average roughness with a correlation coefficient of 0.9982. Furthermore, the proposed AO-assisted system is in good agreement with the stylus method and less than 9.73% error values can be consistently obtained.

Ocular wavefront aberration and refractive error in pre-school children

Hartmann–Shack images taken from an archived collection of SureSight refractive measurements of pre-school children in Oxford County, Ontario, Canada were retrieved and re-analyzed. Higher-order aberrations were calculated over the age range of 3 to 6 years. These higher-order aberrations were compared with respect to magnitudes of ametropia. Subjects were classified as emmetropic (range −0.5 to + 0.5D), low hyperopic (+ 0.5 to +2D) and high hyperopic (+2D or more) based upon the resulting spherical equivalent. Higher-order aberrations were found to increase with higher levels of hyperopia (p < 0.01). The strongest effect was for children showing more than +2.00D of hyperopia. The correlation coefficients were small in all of the higher-order aberrations; however, they were significant (p < 0.01). These analyses indicate a weak association between refractive error and higher-order aberrations in pre-school children.

레이돔 굴절 오차 보상을 위한 적응 파티클 필터 설계

Radome aberration error causes degradation of miss distance as well as stability of high maneuver missile system with RF seeker. A study about radome compensation method is important in this kind of missile system design. Several kinds of methods showed good compensation performance in their paper. Proposed adaptive Particle filter estimates line of sight rate excluding the radome induced error. This paper shows effectiveness of adaptive Particle filter as compensation method of radome aberration error. Robust performance of this filter depends on external aiding measurement, target acceleration. Tuning of system error covariance can make this filter unsensitive against the error of target acceleration information. This paper demonstrates practical usage of adaptive Particle filter for reducing miss distance and increasing stability against disturbance of radome aberration error through performance analysis.

Performance of a satellite-to-ground downlink coherent lasercom system with random tracking error of receiver

We analyze the performance of a satellite-to-ground downlink coherent lasercom system taking into account the combined effects of atmospheric wavefront aberration and tracking error of the receiver. We revise the wavefront phase variance in the case where the tracking error of the receiver terminal is present. We consider the example of the BPSK modulation scheme and show that the tracking error of the receiver terminal greatly increases the bit error probability of the coherent system. We show the optimum aperture diameter of the receiver. This study can benefit the satellite-to-ground downlink coherent lasercom system design.

Altered electrocortical brain activity after ACL reconstruction during force control

Afferent proprioceptive information from the knee joint may be altered due to a reconstruction of the anterior cruciate ligament (ACL), which could result in changes of cortical activity. The aim of the study is to look if force sensation and cortical activation measured by EEG are influenced by an ACL-reconstruction when performing a force reproduction task. Nine patients after ACL reconstruction and nine healthy controls were asked to reproduce 50% of their maximal voluntary isometric contraction (MVIC) reproduction. EEG power values related to frequency bands and the error in reproduction were collected while performing the force reproduction. The aberration error demonstrated no significant differences between groups. The cortical activity results in significant higher frontal Theta power during the force reproduction task with the reconstructed limb (F3 and Fz: p < 0.05) of the ACL group compared to the controls. The EEG was able to measure changes in electrocortical activity after ACL-reconstruction in force reproduction, whereas performance data was not affected. The results were discussed in terms of differences in attentional control with involvement of the anterior cingulate cortex related to higher frontal Theta power in the ACL patients.

The Impact of the Boston Ocular Surface Prosthesis on Wavefront Higher-Order Aberrations

To evaluate the effect of the Boston Ocular Surface Prosthesis (Boston Foundation for Sight) on higher-order wavefront aberrations in eyes with keratoconus, eyes that have undergone penetrating keratoplasty, eyes that have undergone refractive surgery, and eyes with ocular surface diseases. Prospective, clinical study. The study evaluated 56 eyes of 39 patients with irregular astigmatism who were treated with the Boston Ocular Surface Prosthesis when conventional treatments failed. Patients were sorted into 4 clinical groups based on the underlying cause of irregular astigmatism, including keratoconus (group 1), post-penetrating keratoplasty (group 2), post-refractive surgery (group 3), and ocular surface diseases (group 4). Another 6 eyes of 5 patients who were treated with rigid gas permeable lenses also were evaluated. Best-corrected visual acuity; topographic refractive indices, including spherical, cylindrical, spherical equivalent values; and higher-order and total wavefront aberration errors were noted at baseline and after fitting the lens. In all groups, higher-order wavefront aberration error was noted to decrease significantly in eyes wearing the Boston Ocular Surface Prosthesis (P<.001, P=.001, P=.002, and P=.001, respectively). By post hoc analysis, significant differences in the level of higher-order aberrations were observed only between groups 1 and 4 (P=.012) and groups 1 and 2 (P=.033). In the overall group, mean correction rate of higher-order aberration error with the Boston Ocular Surface Prosthesis was 72.3%. However, in eyes with rigid gas permeable lenses, 2 eyes demonstrated increased higher-order aberration error, whereas the mean correction rate in other 4 eyes was only 42.5%. With its unique structure, the Boston Ocular Surface Prosthesis was found to be very effective in reducing higher-order wavefront aberrations in patients with irregular astigmatism resulting from a number of corneal and ocular surface conditions who had not responded satisfactorily to conventional methods of optical correction.

Analysis of comprehensive effects of piston error and sub-aperture aberrations on the image quality of sparse-optical-synthetic-aperture system

To improve the image quality of sparse-optical-synthetic-aperture system, the effects of sub-aperture self aberrations and piston errors among different sub-apertures should be considered comprehensively. Based on the pupil of sparse-optical-synthetic-aperture system, the system Strehl Ratio (SR) is deduced using the principle of Fourier optics, which leads to the theoretical result of the systems SR metric with the form of separated sub-aperture aberration and piston error. As for the bi-aperture system, the variances of the system SR metric are calculated and analyzed with different sub-apertures aberrations for conditions of corrected piston error and un-corrected piston error. Therefore, the comprehensive effects of sub-aperture aberrations and the piston errors among different sub-apertures on the system image quality are analyzed theoretically. From these analyses, the physical mechanism for the comprehensive effect of sub-aperture aberration and the piston error on the sparse-optical-synthetic-aperture system image quality is revealed, and it could be seen that the compensation of piston error is meaningful only if the sub-aperture self aberration is corrected to be in a certain limit.

Agreement measurement of ocular wavefront aberrations with three different aberrometers

To assess the repeatability and difference of ocular wavefront aberrations measured with ray-tracing, dynamic skiascopy, and Hartmann-Shack aberrometers. It was an agreement study. Ocular aberrations data obtained by using iTrace (Tracey Technologies), OPD SCAN (Nidek) and WASCA (Zeiss) wavefront aberrometers were analyzed. Eighty six eyes of 45 patients were measured three times. The difference between the measurement and the mean of three consecutive measurements were analyzed to verify the reproducibility. The difference in sphere, cylinder, spherical equivalent (SEQ) and high order aberration (HOA) errors obtained from different aberrometers were evaluated. Repeatability errors of these three wavefront analyzer were found to be low. Comparisons on the same eye showed that there was a significant difference (P < 0.01) in sphere and cylinder between ray-tracing aberrometer and the others in high SEQ group (>or= -6.00 diopter). For HOA, all aberrometers obtained similar results in low SEQ group (< -6.00 diopter). In the high SEQ group, the ray-tracing aberrometer showed statistically higher data in HOA and coma (P < 0.01), and there was no significant difference between the skiascopy and the Hartmann-Shack aberrometer. The iTrace-OPD and iTrace-WASCA HOA difference correlated with spherical equivalent in the high SEQ group (r = -0.418, -0.399, P < 0.01). All devices produced similar results of reproducibility, but showed varying results in the ocular total wavefront reading.

Robust Method for the Automatic Characterization of a Wooden Board's Geometrical State

ABSTRACT This article presents an algorithm for characterizing and detecting geometric faults in a wooden board. It is developed for integration into a quality control system in factories. The industrial environment where this system will be implemented is characterized by high levels of variation stemming from measurement noise and operating conditions. Geometrical defects in a board can often be summarized under four types of deformations: twist, bow, spring, and transversal alignment. A computer vision system with four cameras is developed and used to obtain a 3D representation of the board surface. The surfaces are digitized using “structured light” active vision techniques. The range of images obtained from the computer vision network can be considered as the input of the proposed algorithm. This algorithm consists of the following five steps: (1) transformation of the spatial position and orientation of each camera into a common reference system; (2) data filtering to eliminate aberrant errors originating from splinters or from tears on the board's surface; (3) integration of multiple local surfaces into a 3D global representation of the board; (4) extraction of significant feature points by means of polynomial surfaces obtained from linear regression; and (5) characterization and classification of different geometrical defects using the extracted points. This classification provides the basis for making a final decision with respect to the surface quality of the inspected part. Different types of defects combined with different noise levels were used to validate the algorithm. The results show that high-quality performance and precision can be achieved with this proposed method.

Sensitivity study of two high-throughput resolution metrics for photoresists

The resolution of chemically amplified resists is becoming an increasing concern, especially for lithography in the extreme ultraviolet (EUV) regime. Large-scale screening is currently under way to identify resist platforms that can support the demanding specifications required for EUV lithography. Current screening processes would benefit from the development of metrics that can objectively quantify resist resolution in a high-throughput fashion. Here we examine two high-throughput metrics for resist resolution determination. After summarizing their details and justifying their utility, we characterize the sensitivity of both metrics to known uncertainties in exposure tool aberrations and focus control. For an implementation at EUV wavelengths, we report aberration and focus-limited error bars in extracted resolution of approximately 1.25 nm rms for both metrics, making them attractive candidates for future screening and downselection efforts.

Neural Systems for Error Monitoring

Complex behavior requires a flexible system that maintains task performance in the context of specific goals, evaluating behavioral progress, adjusting behavior as needed, and adapting to changing contingencies. Generically referred to as performance monitoring, a key component concerns the identification and correction of differences between an intended and an executed response (i.e., an error). Brain mapping experiments have now identified the temporal and spatial components of a putative error-processing system in the large-scale networks of the human brain. Most of this work has focused on the medial frontal cortex and an associated electrophysiological component known as the error-related negativity (or error negativity). Although the precise role, or roles, of this region still remain unknown, investigations of error processing have identified a cluster of modules in the medial frontal cortex involved in monitoring/maintaining ongoing behavior and motivating task sets. Other regions include bilateral anterior insula/inferior operculum and lateral prefrontal cortex. Recent work has begun to uncover how individual differences might affect the modules recruited for a task, in addition to the identification of associations between pathological states and aberrant error signals, leading to insights about possible mechanisms of neuropsychiatric illness. NEUROSCIENTIST 13(2):160—172, 2007.