The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
William H. Warren - One of the best experts on this subject based on the ideXlab platform.
-
Rotational error in path integration: encoding and execution errors in Angle reproduction
Experimental Brain Research, 2017Co-Authors: Elizabeth R. Chrastil, William H. WarrenAbstract:Path integration is fundamental to human navigation. When a navigator leaves home on a complex outbound path, they are able to keep track of their approximate position and orientation and return to their starting location on a direct homebound path. However, there are several sources of error during path integration. Previous research has focused almost exclusively on encoding error —the error in registering the outbound path in memory. Here, we also consider execution error— the error in the response, such as turning and walking a homebound trajectory. In two experiments conducted in ambulatory virtual environments, we examined the contribution of execution error to the rotational component of path integration using Angle reproduction tasks. In the reproduction tasks, participants rotated once and then rotated again to face the original direction, either reproducing the initial turn or turning through the Supplementary Angle. One outstanding difficulty in disentangling encoding and execution error during a typical Angle reproduction task is that as the encoding Angle increases, so does the required response Angle. In Experiment 1, we dissociated these two variables by asking participants to report each encoding Angle using two different responses: by turning to walk on a path parallel to the initial facing direction in the same (reproduction) or opposite (Supplementary Angle) direction. In Experiment 2, participants reported the encoding Angle by turning both rightward and leftward onto a path parallel to the initial facing direction, over a larger range of Angles. The results suggest that execution error, not encoding error, is the predominant source of error in angular path integration. These findings also imply that the path integrator uses an intrinsic (action-scaled) rather than an extrinsic (objective) metric.
Lih-jyh Fuh - One of the best experts on this subject based on the ideXlab platform.
-
The Collum Angle of the maxillary central incisors in patients with different types of malocclusion
Journal of Dental Sciences, 2012Co-Authors: Yen-wen Shen, Jui-ting Hsu, Yi-hui Wang, Heng-li Huang, Lih-jyh FuhAbstract:Abstract Background/purpose The Collum Angle (the Supplementary Angle of the crown-root Angle) of the maxillary central incisors is extremely important for patients who are undergoing orthodontic treatment and who are to receive an implant restoration. However, there is no report on the Collum Angle in Taiwanese. Therefore, the purpose of this study was to evaluate the Collum Angle of the maxillary central incisors in Taiwanese patients with different types of malocclusion. Materials and methods This study collected 124 samples of lateral cephalometric radiographs (38 radiographs from male patients and 86 from female patients). The age of sampled patients ranged 8–58 (mean, 19.9) years. Samples were divided into four groups according to the malocclusion type, and the Collum Angle of the maxillary central incisors in each group was measured. A one-way ANOVA and the Scheffe test were used to compare whether or not the Angle differed among the groups. Results The average value of the Collum Angle was 6.1° ± 5.2° for class-I malocclusions, 5.3° ± 4.2° for class-II division-I malocclusions, 10.6° ± 4.4° for class-II division-2 malocclusions, and 5.6° ± 5.1° for class-III malocclusions. A statistical analysis showed that the Collum Angle of the maxillary central incisors for patients with class-II division-2 malocclusions significantly exceeded values in the other three groups. Conclusion Compared to groups with other malocclusion types, the Collum Angle of natural teeth for patients with class-II division-2 malocclusions was the greatest.
Neveen Mohamad Fakhry - One of the best experts on this subject based on the ideXlab platform.
-
Maxillary Central Incisors’ collum Angle in different skeletal vertical malocclusions – A Cephaometric study
Egyptian Dental Journal, 2019Co-Authors: Nahla Gomaa, Shaimaa Elmarhoumy, Neveen Mohamad FakhryAbstract:Introduction: The Collum Angle can be defined as a crown root Supplementary Angle of maxillary central incisors. The aim of the study was to assess the maxillary central incisors’ collum Angle in a sample of Egyptian patients with different vertical malocclusions using cephalometric radiographs. Methods: Ninety lateral cephalometric radiographs were collected and divided into three groups, with equal size, according to lateral cephalograms (SN-GoGn Angle). Group І: consisted of lateral cephalmetric radiographs of 30 who had the strongest predominance of horizontal growth pattern (SN-GoGn ≤28o), Group ІІ: consisted of lateral cephalmetric radiographs of 30 subjects who had the strongest predominance of vertical growth pattern (SN-GoGn ≥35o). Angular and linear parameters on cephalometric radiograph for each subject were measured to identify the facial growth patterns, and Collum Angle was then measured. Results: mean of collum Angle for the maxillary central incisor in horizontal growth pattern sample was 7.8°±2.2° with minimum being 5° and maximum 14°. The mean values for vertical growth pattern was 2.1°±2.1° with minimum 0° and a maximum 6°. Paired samples t-test comparison revealed that there was a high significant increase in maxillary central incisor collum Angle in horizontal growers than in vertical growers, mean difference being 5.7°±1°. Conclusion: Maxillary central incisor collum Angle in horizontal growers is higher than in vertical growers.
Elizabeth R. Chrastil - One of the best experts on this subject based on the ideXlab platform.
-
Rotational error in path integration: encoding and execution errors in Angle reproduction
Experimental Brain Research, 2017Co-Authors: Elizabeth R. Chrastil, William H. WarrenAbstract:Path integration is fundamental to human navigation. When a navigator leaves home on a complex outbound path, they are able to keep track of their approximate position and orientation and return to their starting location on a direct homebound path. However, there are several sources of error during path integration. Previous research has focused almost exclusively on encoding error —the error in registering the outbound path in memory. Here, we also consider execution error— the error in the response, such as turning and walking a homebound trajectory. In two experiments conducted in ambulatory virtual environments, we examined the contribution of execution error to the rotational component of path integration using Angle reproduction tasks. In the reproduction tasks, participants rotated once and then rotated again to face the original direction, either reproducing the initial turn or turning through the Supplementary Angle. One outstanding difficulty in disentangling encoding and execution error during a typical Angle reproduction task is that as the encoding Angle increases, so does the required response Angle. In Experiment 1, we dissociated these two variables by asking participants to report each encoding Angle using two different responses: by turning to walk on a path parallel to the initial facing direction in the same (reproduction) or opposite (Supplementary Angle) direction. In Experiment 2, participants reported the encoding Angle by turning both rightward and leftward onto a path parallel to the initial facing direction, over a larger range of Angles. The results suggest that execution error, not encoding error, is the predominant source of error in angular path integration. These findings also imply that the path integrator uses an intrinsic (action-scaled) rather than an extrinsic (objective) metric.
Fernando Santonja-medina - One of the best experts on this subject based on the ideXlab platform.
-
Coronal and axial alignment relationship in Caucasian patients with osteoarthritis of the knee
Scientific Reports, 2021Co-Authors: Vicente J. León-muñoz, Silvio Manca, Mirian López-lópez, Francisco Martínez-martínez, Fernando Santonja-medinaAbstract:Individualized pre-operative assessment of the patterns of the lower extremity anatomy and deformities in patients undergoing total knee arthroplasty seems essential for a successful surgery. In the present study, we investigated the relationship among the coronal alignment and the rotational profile of the lower extremities in the Caucasian population with end-stage knee osteoarthritis. We conducted a prospective study of 385 knees that underwent a pre-operative three-dimensional computed tomography-based model. The lower extremity alignment was determined (mechanical tibiofemoral or hip-knee-ankle Angle, Supplementary Angle of the femoral lateral distal Angle, and proximal medial tibial Angle). For each case, the femoral distal rotation (condylar twist Angle), the femoral proximal version, and the tibial torsion were determined. As the coronal alignment changed from varus to valgus, the femoral external rotation increased (r = 0.217; p
-
Patient-Specific Instrumentation Accuracy Evaluated with 3D Virtual Models
Journal of Clinical Medicine, 2021Co-Authors: Vicente J. León-muñoz, Silvio Manca, Mirian López-lópez, Francisco Martínez-martínez, Andrea Parrinello, Gianluca Galloni, Fernando Santonja-medinaAbstract:There have been remarkable advances in knee replacement surgery over the last few decades. One of the concerns continues to be the accuracy in achieving the desired alignment. Patient-specific instrumentation (PSI) was developed to increase component placement accuracy, but the available evidence is not conclusive. Our study aimed to determine a PSI system’s three-dimensional accuracy on 3D virtual models obtained by post-operative computed tomography. We compared the angular placement values of 35 total knee arthroplasties (TKAs) operated within a year obtained with the planned ones, and we analyzed the possible relationships between alignment and patient-reported outcomes. The mean (SD) discrepancies measured by two experienced engineers to the planned values observed were 1.64° (1.3°) for the hip–knee–ankle Angle, 1.45° (1.06°) for the Supplementary Angle of the femoral lateral distal Angle, 1.44° (0.97°) for the proximal medial tibial Angle, 2.28° (1.78°) for tibial slope, 0.64° (1.09°) for femoral sagittal flexion, and 1.42° (1.06°) for femoral rotation. Neither variables related to post-operative alignment nor the proportion of change between pre-and post-operative alignment influenced the patient-reported outcomes. The evaluated PSI system’s three-dimensional alignment analysis showed a statistically significant difference between the angular values planned and those obtained. However, we did not find a relevant effect size, and this slight discrepancy did not impact the clinical outcome.